Digital Camera Patent

Arrangement of usage indicator in a recyclable, digital camera

Digital Camera Patent Abstract

A recyclable, one-time use print on demand, digital camera comprises an image sensor device for sensing an image. A processor processes the image sensed by the image sensor device. The camera includes a supply of print media on to which an image processed by the processor is printed. A printhead is provided for printing said sensed image on the print media. An indicator for indicating usage of the camera is arranged within a housing of the camera. A separating device separates a part of the print media on to which an image has been printed from a remainder of the supply of print media. The separating device acts on the indicator for changing the indication of usage as part of the operation of separating the part of the print media from the remainder of the supply of the print media.

Digital Camera Patent Claims

I claim:

1. A recyclable, print on demand, digital camera comprising:

an image sensor device for sensing an image;

a processing means for processing an image sensed by the image sensor device;

a supply of print media on to which an image processed by the processing means is printed;

a printhead for printing said sensed image on the print media;

an indicating means for indicating an image count; and

a separating means for separating a part of the print media on to which an image has been printed from a remainder of the supply of print media, the separating means acting on the indicating means for changing said image count as part of the operation of separating each said part from the remainder of the supply of print media.

2. The camera of claim 1 in which the printhead is a pagewidth printhead which has a length corresponding to one of a length and width of an image to be printed.

3. The camera of claim 2 in which the supply of print media moves past the printhead in a direction substantially normal to a longitudinal axis of the printhead, the separating means being displaceable in a direction parallel to said longitudinal axis for separating said part of the supply of print media from the remainder of the supply of print media.

4. The camera of claim 3 in which the separating means includes an engaging formation which engages a complementary formation of the indicating means to change the indication of usage displayed by the indicating means as the separating means moves along its path of travel, the engaging formation and the complementary formation being such that the separating means causes a change in the indication of usage in one direction of traversal of said path of travel of the separating means but does not cause a change in said indication of usage in an opposite direction of traversal of said path of travel.

5. The camera of claim 4 in which the separating means causes a change in the indication of usage as the separating means returns to its rest position after completion of a separating operation.

6. The camera of claim 1 in which the supply of print media is replenishable, the supply of print media being arranged on a chassis with a removable print media path defining means displaceably arranged relative to the chassis.

7. The camera of claim 6 in which the indicating means is arranged on the chassis and the separating means is carried on the print media path defining means.

8. A recyclable, print on demand, digital camera comprising:

an image sensor device for sensing an image;

a processing means for processing an image sensed by the image sensor device;

a supply of print media on to which an image processed by the processing means is printed;

a printhead for printing said sensed image on the print media;

an indicating means for indicating an image count;

a separating means for separating a part of the print media on to which an image has been printed from a remainder of the supply of print media, the separating means acting on the indicating means for changing said image count as part of the operation of separating each said part from the remainder of the supply of print media;

the printhead being a pagewidth printhead which has a length corresponding to one of a length and width of an image to be printed;

the supply of print media moves past the printhead in a direction substantially normal to a longitudinal axis of the printhead, the separating means being displaceable in a direction parallel to said longitudinal axis for separating said part of the supply of print media from the remainder of the supply of print media; and

the separating means includes an engaging formation which engages a complementary formation of the indicating means to change the indication of usage displayed by the indicating means as the separating means moves along its path of travel, the engaging formation and the complementary formation being such that the separating means causes a change in the indication of usage in one direction of traversal of said path of travel of the separating means but does not cause a change in said indication of usage in an opposite direction of traversal of said path of travel.

Digital Camera Patent Description

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

FIELD OF THE INVENTION

This invention relates to a recyclable digital camera. More particularly, the invention relates to a recyclable, one-time use, print on demand, digital camera. More specifically, the invention relates to an arrangement for indicating use of such a camera.

BACKGROUND OF THE INVENTION

Recently, the concept of a "single use" disposable camera has become an increasingly popular consumer item. Disposable camera systems presently on the market normally includes an internal film roll and a simplified gearing mechanism for traversing the film roll across an imaging system including a shutter and lensing system. The user, after utilising a single film roll returns the camera system to a film development center for processing. The film roll is taken out of the camera system and processed and the prints returned to the user. The camera system is then able to be re-manufactured through the insertion of a new film roll into the camera system, the replacement of any worn or wearable parts and the re-packaging of the camera system in accordance with requirements. In this way, the concept of a single use "disposable" camera is provided to the consumer.

Recently, a camera system has been proposed by the present applicant which provides for a handheld camera device having an internal printhead, image sensor and processing means such that images sensed by the image sensing means, are processed by the processing means and adapted to be instantly printed out by the printing means on demand. The proposed camera system further discloses a system of internal "print rolls" carrying print media such as film on to which images are to be printed in addition to ink to supply to the printing means for the printing process. The print roll is further disclosed to be detachable and replaceable within the camera system.

Unfortunately, such a system is likely to only be constructed at a substantial cost and it would be desirable to provide for a more inexpensive form of instant camera system which maintains a substantial number of the quality aspects of the aforementioned arrangement.

In particular, in any "disposable camera" it would be desirable to provide for a simple and rapid form of replenishment of the consumable portions in any disposable camera so that the disposable camera can be readily and rapidly serviced by replenishment and returned to the market place.

It would be further desirable to provide for a simplified form of automated picture counting in a disposable camera system.

SUMMARY OF THE INVENTION

According to the invention, there is provided a recyclable, one-time use, print on demand, digital camera comprising

an image sensor device for sensing an image;

a processing means for processing an image sensed by the image sensor device;

a supply of print media on to which an image processed by the processing means is printed;

a print head for printing said sensed image on the print media;

an indicating means for indicating usage of the camera; and

a separating means for separating a part of the print media on to which an image has been printed from a remainder of the supply of print media, the separating means acting on the indicating means for changing said indication of usage as part of the operation of separating said part from the remainder of the supply of the print media.

The print head may be a pagewidth print head which has a length corresponding to one of a length and width of an image to be printed. Generally, the print head will have a length corresponding to the width of an image to be printed.

The supply of print media may move past the print head in a direction substantially normal to a longitudinal axis of the print head, the separating means being displaceable in a direction parallel to said longitudinal axis for separating said part of the supply of print media from the remainder of the supply of print media.

The separating means may be in the form of a cutting element which bears against a bearing surface defined by a chassis of the camera to effect separation of said part from the remainder of the supply of print head.

Further, the indicating means may be in the form of a wheel rotatably arranged on the chassis. The wheel may have numbers arranged thereon which are visible through a window in a housing of the camera. The separating means may then act on the wheel either to decrement or increment the visible number to show the number of images remaining or the number of images printed, as the case may be.

The separating means may thus include an engaging formation which engages a complementary formation of the indicating means to change the indication of usage displayed by the indicating means as the separating means moves along its path of travel, the engaging formation and the complementary formation being such that the separating means causes a change in the indication of usage in one direction of traversal of the path of travel of the separating means but does not cause a change in said indication of usage in an opposite direction of traversal of the path of travel.

More particularly, the cutting wheel constituting the separating means may be arranged on a carrier. The carrier may have a pawl projecting therefrom, the pawl being the engaging formation. The wheel of the indicating means may have ratchet teeth arranged about its circumference to be engaged by the pawl as the separating means traverses its path of travel.

Preferably, the separating means causes a change in the indication of usage as the separating means returns to its rest position after completion of a separating operation.

The supply of print media may be replenishable, the supply of print media being arranged on the chassis with a removable print media path defining means, in the form of a platten, displaceably arranged relative to the chassis. The indicating means may be arranged on the chassis, as described above, with the separating means being carried on the print media path defining means.

BRIEF DESCRIPTION OF THE DRAWINGS

Notwithstanding any other forms which may fall within the scope of the present invention, preferred forms of the invention will now be described, by way of example only, with reference the accompanying drawings in which:

FIG. 1 illustrates a side front perspective view of the assembled camera of the preferred embodiment;

FIG. 2 illustrates a back side perspective view, partly exploded, of the preferred embodiment;

FIG. 3 is a side perspective view of the chassis of the preferred embodiment;

FIG. 4 is a side perspective view of the chassis illustrating the insertion of the electric motors;

FIG. 5 is an exploded perspective of the ink supply mechanism of the preferred embodiment;

FIG. 6 is a side perspective of the assembled form of the ink supply mechanism of the preferred embodiment;

FIG. 7 is a front perspective view of the assembled form of the ink supply mechanism of the preferred embodiment;

FIG. 8 is an exploded perspective of the platen unit of the preferred embodiment;

FIG. 9 is a side perspective view of the assembled form of the platen unit;

FIG. 10 is also a side perspective view of the assembled form of the platen unit;

FIG. 11 is an exploded perspective unit of a printhead recapping mechanism of the preferred embodiment;

FIG. 12 is a close up exploded perspective of the recapping mechanism of the preferred embodiment;

FIG. 13 is an exploded perspective of the ink supply cartridge of the preferred embodiment;

FIG. 14 is a close up perspective, partly in section, of the internal portions of the ink supply cartridge in an assembled form;

FIG. 15 is a schematic block diagram of one form of chip layer of the image capture and processing chip of the preferred embodiment;

FIG. 16 is an exploded perspective illustrating the assembly process of the preferred embodiment;

FIG. 17 illustrates a front exploded perspective view of the assembly process of the preferred embodiment

FIG. 18 illustrates a side perspective view of the assembly process of the preferred embodiment;

FIG. 19 illustrates a side perspective view of the assembly process of the preferred embodiment;

FIG. 20 is a perspective view illustrating the insertion of the platen unit in the preferred embodiment;

FIG. 21 illustrates the interconnection of the electrical components of the preferred embodiment;

FIG. 22 illustrates the process of assembling the preferred embodiment; and

FIG. 23 is a perspective view further illustrating the assembly process of the preferred embodiment.

DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS

Turning initially simultaneously to FIG. 1, and FIG. 2 there is illustrated perspective views of an assembled camera constructed in accordance with the preferred embodiment with FIG. 1 showing a front side perspective view and FIG. 2 showing a back side perspective view. The camera I includes a paper or plastic film jacket 2 which can include simplified instructions 3 for the operation of the camera system 1. The camera system 1 includes a first "take" button 4 which is depressed to capture an image. The captured image is output via output slot 6. A further copy of the image can be obtained through depressing a second "printer copy" button 7 whilst an LED light 5 is illuminated. The camera system also provides the usual view finder 8 in addition to a CCD image capture/lensing system 9.

The camera system 1 provides for a standard number of output prints after which the camera system 1 ceases to function. A prints left indicator slot 10 is provided to indicate the number of remaining prints. A refund scheme at the point of purchase is assumed to be operational for the return of used camera systems for recycling.

Turning now to FIG. 3, the assembly of the camera system is based around an internal chassis 12 which can be a plastic injection molded part. A pair of paper pinch rollers 28, 29 utilized for decurling are snap fitted into corresponding frame holes eg. 26, 27.

As shown in FIG. 4, the chassis 12 includes a series of mutually opposed prongs eg. 13, 14 into which is snapped fitted a series of electric motors 16, 17. The electric motors 16, 17 can be entirely standard with the motor 16 being of a stepper motor type and include a cogged end portion 19, 20 for driving a series of gear wheels. A first set of gear wheels is provided for controlling a paper cutter mechanism and a second set is provided for controlling print roll movement.

Turning next to FIGS. 5 to 7, there is illustrated an ink supply mechanism 40 utilized in the camera system. FIG. 5 illustrates a back exploded perspective view, FIG. 6 illustrates a back assembled view and FIG. 7 illustrates a front assembled view. The ink supply mechanism 40 is based around an ink supply cartridge 42 which contains printer ink and a printhead mechanism for printing out pictures on demand. The ink supply cartridge 42 includes a side aluminum strip 43 which is provided as a shear strip to assist in cutting images from a paper roll.

A dial mechanism 44 is provided for indicating the number of "prints left". The dial mechanism 44 is snap fitted through a corresponding mating portion 46 so as to be freely rotatable.

As shown in FIG. 6, the printhead includes a flexible PCB strip 47 which interconnects with the printhead and provides for control of the printhead. The interconnection between the flexible PCB strip and an image sensor and printhead chip can be via Tape Automated Bonding (TAB) Strips 51, 58. A molded aspherical lens and aperture shim 50 (FIG. 5) is also provided for imaging an image onto the surface of the image sensor chip normally located within cavity 53 and a light box module or hood 52 is provided for snap fitting over the cavity 53 so as to provide for proper light control. A series of decoupling capacitors e.g. 34 can also be provided. Further, a plug 121 (FIG. 7) is provided for re-plugging ink holes after refilling. A series of guide prongs e.g. 55-57 are further provided for guiding the flexible PCB strip 47.

The ink supply mechanism 40 interacts with a platen unit 60 which guides print media under a printhead located in the ink supply mechanism. FIG. 8 shows an exploded view of the platen unit 60, while FIGS. 9 and 10 show assembled views of the platen unit 60. The platen unit 60 includes a first pinch roller 61 which is snap fitted to one side of a platen base 62. Attached to a second side of the platen base 62 is a cutting mechanism 63 which traverses the platen by means of a rod 64 having a screwed thread which is rotated by means of cogged wheel 65 which is also fitted to the platen 62. The screwed thread engages a block 67 which includes a cutting wheel 68 fastened via a fastener 69. Also mounted to the block 67 is a counter actuator which includes a prong 71. The prong 71 acts to rotate the dial mechanism 44 of FIG. 6 upon the return traversal of the cutting wheel. As shown previously in FIG. 6, the dial mechanism 44 includes a cogged surface which interacts with pawl lever 73, thereby maintaining a count of the number of photographs taken on the surface of dial mechanism 44. The cutting mechanism 63 is inserted into the platen base 62 by means of a snap fit via receptacle 74.

The platen 62 includes an internal re-capping mechanism 80 for re-capping the printhead when not in use. The re-capping mechanism 80 includes a sponge portion 81 and is operated via a solenoid coil so as to provide for recapping of the printhead. In the preferred embodiment, there is provided an inexpensive form of printhead re-capping mechanism provided for incorporation into a handheld camera system so as to provide for printhead re-capping of an inkjet printhead.

FIG. 11 illustrates an exploded view of the recapping mechanism 80 whilst FIG. 12 illustrates a close up of the end portion thereof. The re-capping mechanism 80 is structured around a solenoid including a 16 turn coil 75 which can comprise insulated wire. The coil 75 is turned around a first stationary solenoid arm 76 which is mounted on a bottom surface of the platen 62 (FIG. 8) and includes a post portion 77 to magnify effectiveness of operation. The arm 76 can comprise a ferrous material.

A second moveable arm 78 of the solenoid actuator is also provided, the arm 78 is moveable and is also made of ferrous material. Mounted on the arm is a sponge portion surrounded by an elastomer strip 79. The elastomer strip 79 is of a generally arcuate cross-section and acts as a leaf spring against the surface of the printhead ink supply cartridge 42 (FIG. 5) so as to provide for a seal against the surface of the printhead ink supply cartridge 42. In the quiescent position elastomer spring units 87, 88 act to resiliently deform the elastomer seal 79 against the surface of the ink supply unit 42.

When it is desired to operate the printhead unit, upon the insertion of paper, the solenoid coil 75 is activated so as to cause the arm 78 to move down to be adjacent to the end plate 76. The arm 78 is held against end plate 76 while the printhead is printing by means of a small "keeper current" in coil 75. Simulation results indicate that the keeper current can be significantly less than the actuation current. Subsequently, after photo printing, the paper is guillotined by the cutting mechanism 63 of FIG. 8 acting against Aluminum Strip 43 of FIG. 5, and rewound so as to clear the area of the re-capping mechanism 80. Subsequently, the current is turned off and springs 87, 88 return the arm 78 so that the elastomer seal is again resting against the printhead ink supply cartridge.

It can be seen that the preferred embodiment provides for a simple and inexpensive means of re-capping a printhead through the utilization of a solenoid type device having a long rectangular form. Further, the preferred embodiment utilizes minimal power in that currents are only required whilst the device is operational and additionally, only a low keeper current is required whilst the printhead is printing.

Turning next to FIGS. 13 and 14, FIG. 13 illustrates an exploded perspective of the ink supply cartridge 42 whilst FIG. 14 illustrates a close up sectional view of a bottom of the ink supply cartridge 42 with the printhead unit in place. The ink supply cartridge 42 is based around a pagewidth printhead 102 which comprises a long slither of silicon having a series of holes etched on the back surface for the supply of ink to a front surface of the silicon wafer for subsequent ejection via a micro electro mechanical system. The form of ejection can be many different forms such as those set out in the tables below.

Of course, many other inkjet technologies, as referred to the attached tables below, can also be utilized when constructing a printhead unit 102. The fundamental requirement of the ink supply cartridge 42 being the supply of ink to a series of color channels etched through the back surface of the printhead 102. In the description of the preferred embodiment, it is assumed that a three color printing process is to be utilized so as to provide full color picture output. Hence, the ink supply unit 42 includes three ink supply reservoirs being a cyan reservoir 104, a magenta reservoir 105 and a yellow reservoir 106. Each of these reservoirs is configured to store ink and includes a corresponding sponge type material 107-109 which assists in stabilizing ink within the corresponding ink channel and therefore preventing the ink from sloshing back and forth when the printhead is utilized in a handheld camera system. The reservoirs 104, 105, 106 are formed through the mating of first exterior plastic piece 110 mating with a second base piece) 111.

A first end of the base piece 111 includes a series of air inlets 113-115. The air inlets lead to a corresponding winding channel which is hydrophobically treated so as to act as an ink repellent and therefore repel any ink that may flow along the air inlet channel. The air inlet channel further takes a convoluted path further assisting in resisting any ink flow out of the chambers 104-106. An adhesive tape portion 117 is provided for sealing the channels within end portion 118.

At the top end, there is included a series of refill holes for refilling corresponding ink supply chambers 104, 105, 106. A plug 121 is provided for sealing the refill holes.

Turning now to FIG. 14, there is illustrated a close up perspective view, partly in section, through the ink supply cartridge 42 of FIG. 13 when formed as a unit. The ink supply cartridge includes the three color ink reservoirs 104, 105, 106 which supply ink to different portions of the back surface of printhead 102 which includes a series of apertures 128 defined therein for carriage of the ink to the front surface.

The ink supply unit includes two guide walls 124, 125 which separate the various ink chambers and are tapered into an end portion abutting the surface of the printhead 102. The guide walls are further mechanically supported at regular spaces by block portions 126 which are placed at regular intervals along the length of the printhead supply unit. The block portions 126 leave space at portions close to the back of printhead 102 for the flow of ink around the back surface thereof.

The printhead supply unit is preferably formed from a multi-part plastic injection mold and the mold pieces e.g. 110, 111 (FIG. 13) snap together around the sponge pieces 107, 108, 109. Subsequently, a syringe type device can be inserted in the ink refill holes and the ink reservoirs filled with ink with the air flowing out of the air outlets 113-115. Subsequently, the adhesive tape portion 117 and plug 121 are attached and the printhead tested for operation capabilities. Subsequently, the ink supply cartridge 42 can be readily removed for refilling by means of removing the ink supply cartridge, performing a washing cycle, and then utilizing the holes for the insertion of a refill syringe filled with ink for refilling the ink chamber before returning the ink supply cartridge 42 to a camera.

Turning now to FIG. 15, there is shown an example layout of the Image Capture and Processing Chip (ICP) 48.

The Image Capture and Processing Chip 48 provides most of the electronic functionality of the camera with the exception of the printhead chip. The chip 48 is a highly integrated system. It combines CMOS image sensing, analog to digital conversion, digital image processing, DRAM storage, ROM, and miscellaneous control functions in a single chip.

The chip is estimated to be around 32 mm.sup.2 using a leading edge 0.18 micron CMOS/DRAM/APS process. The chip size and cost can scale somewhat with Moore's law, but is dominated by a CMOS active pixel sensor array 201, so scaling is limited as the sensor pixels approach the diffraction limit.

The ICP 48 includes CMOS logic, a CMOS image sensor, DRAM, and analog circuitry. A very small amount of flash memory or other non-volatile memory is also preferably included for protection against reverse engineering.

Alternatively, the ICP can readily be divided into two chips: one for the CMOS imaging array, and the other for the remaining circuitry. The cost of this two chip solution should not be significantly different than the single chip ICP, as the extra cost of packaging and bond-pad area is somewhat cancelled by the reduced total wafer area requiring the color filter fabrication steps.

The ICP preferably contains the following functions:

Function 1.5 megapixel image sensor Analog Signal Processors Image sensor column decoders Image sensor row decoders Analogue to Digital Conversion (ADC) Column ADC's Auto exposure 12 Mbits of DRAM DRAM Address Generator Color interpolator Convolver Color ALU Halftone matrix ROM Digital halftoning Printhead interface 8 bit CPU core Program ROM Flash memory Scratchpad SRAM Parallel interface (8 bit) Motor drive transistors (5) Clock PLL JTAG test interface Test circuits Busses Bond pads

The CPU, DRAM, Image sensor, ROM, Flash memory, Parallel interface, JTAG interface and ADC can be vendor supplied cores. The ICP is intended to run on 1.5 V to minimize power consumption and allow convenient operation from two AA type battery cells.

FIG. 15 illustrates a layout of the ICP 48. The ICP 48 is dominated by the imaging array 201, which consumes around 80% of the chip area. The imaging array is a CMOS 4 transistor active pixel design with a resolution of 1,500.times.1,000. The array can be divided into the conventional configuration, with two green pixels, one red pixel, and one blue pixel in each pixel group. There are 750.times.500 pixel groups in the imaging array.

The latest advances in the field of image sensing and CMOS image sensing in particular can be found in the October, 1997 issue of IEEE Transactions on Electron Devices and, in particular, pages 1689 to 1968. Further, a specific implementation similar to that disclosed in the present application is disclosed in Wong et. al, "CMOS Active Pixel Image Sensors Fabricated Using a 1.8 V, 0.25 .mu.m CMOS Technology", IEDM 1996, page 915.

The imaging array uses a 4 transistor active pixel design of a standard configuration. To minimize chip area and therefore cost, the image sensor pixels should be as small as feasible with the technology available. With a four transistor cell, the typical pixel size scales as 20 times the lithographic feature size. This allows a minimum pixel area of around 3.6 .mu.m.times.3.6 .mu.m. However, the photosite must be substantially above the diffraction limit of the lens. It is also advantageous to have a square photosite, to maximize the margin over the diffraction limit in both horizontal and vertical directions. In this case, the photosite can be specified as 2.5 .mu.m.mu.2.5 .mu.m. The photosite can be a photogate, pinned photodiode, charge modulation device, or other sensor.

The four transistors are packed as an `L` shape, rather than a rectangular region, to allow both the pixel and the photosite to be square. This reduces the transistor packing density slightly, increasing pixel size. However, the advantage in avoiding the diffraction limit is greater than the small decrease in packing density.

The transistors also have a gate length which is longer than the minimum for the process technology. These have been increased from a drawn length of 0.18 micron to a drawn length of 0.36 micron. This is to improve the transistor matching by making the variations in gate length represent a smaller proportion of the total gate length.

The extra gate length, and the `L` shaped packing, mean that the transistors use more area than the minimum for the technology. Normally, around 8 .mu.m.sup.2 would be required for rectangular packing. Preferably, 9.75 .mu.m.sup.2 has been allowed for the transistors.

The total area for each pixel is 16 .mu.m.sup.2, resulting from a pixel size of 4 .mu.m.times.4 .mu.m. With a resolution of 1,500.times.1,000, the area of the imaging array 101 is 6,000 .mu.m.times.4,000 .mu.m, or 24 mm.sup.2.

The presence of a color image sensor on the chip affects the process required in two major ways:

The CMOS fabrication process should be optimized to minimize dark current.

Color filters are required. These can be fabricated using dyed photosensitive polyimides, resulting in an added process complexity of three spin coatings, three photolithographic steps, three development steps, and three hardbakes.

There are 15,000 analog signal processors (ASPs) 205, one for each of the columns of the sensor. The ASPs amplify the signal, provide a dark current reference, sample and hold the signal, and suppress the fixed pattern noise (FPN).

There are 375 analog to digital converters 206, one for each four columns of the sensor array. These may be delta-sigma or successive approximation type ADC's. A row of low column ADC's are used to reduce the conversion speed required, and the amount of analog signal degradation incurred before the signal is converted to digital. This also eliminates the hot spot (affecting local dark current) and the substrate coupled noise that would occur if a single high speed ADC was used. Each ADC also has two four bit DAC's which trim the offset and scale of the ADC to further reduce FPN variations between columns. These DAC's are controlled by data stored in flash memory during chip testing.

The column select logic 204 is a 1:1500 decoder which enables the appropriate digital output of the ADCs onto the output bus. As each ADC is shared by four columns, the least significant two bits of the row select control 4 input analog multiplexors.

A row decoder 207 is a 1:1000 decoder which enables the appropriate row of the active pixel sensor array. This selects which of the 1000 rows of the imaging array is connected to analog signal processors. As the rows are always accessed in sequence, the row select logic can be implemented as a shift register.

An auto exposure system 208 adjusts the reference voltage of the ADC 205 in response to the maximum intensity sensed during the previous frame period. Data from the green pixels is passed through a digital peak detector. The peak value of the image frame period before capture (the reference frame) is provided to a digital to analogue converter(DAC), which generates the global reference voltage for the column ADCs. The peak detector is reset at the beginning of the reference frame. The minimum and maximum values of the three RGB color components are also collected for color correction.

The second largest section of the chip is consumed by a DRAM 210 used to hold the image. To store the 1,500.times.1,000 image from the sensor without compression, 1.5 Mbytes of DRAM 210 are required. This equals 12 Mbits, or slightly less than 5% of a 256 Mbit DRAM. The DRAM technology assumed is of the 256 Mbit generation implemented using 0.18 .mu.m CMOS.

Using a standard 8F cell, the area taken by the memory array is 3.11 mm.sup.2. When row decoders, column sensors, redundancy, and other factors are taken into account, the DRAM requires around 4 mm.sup.2.

This DRAM 210 can be mostly eliminated if analog storage of the image signal can be accurately maintained in the CMOS imaging array for the two seconds required to print the photo. However, digital storage of the image is preferable as it is maintained without degradation, is insensitive to noise, and allows copies of the photo to be printed considerably later.

A DRAM address generator 211 provides the write and read addresses to the DRAM 210. Under normal operation, the write address is determined by the order of the data read from the CMOS image sensor 201. This will typically be a simple raster format. However, the data can be read from the sensor 201 in any order, if matching write addresses to the DRAM are generated. The read order from the DRAM 210 will normally simply match the requirements of a color interpolator and the printhead. As the cyan, magenta, and yellow rows of the printhead are necessarily offset by a few pixels to allow space for nozzle actuators, the colors are not read from the DRAM simultaneously. However, there is plenty of time to read all of the data from the DRAM many times during the printing process. This capability is used to eliminate the need for FIFOs in the printhead interface, thereby saving chip area. All three RGB image components can be read from the DRAM each time color data is required. This allows a color space converter to provide a more sophisticated conversion than a simple linear RGB to CMY conversion.

Also, to allow two dimensional filtering of the image data without requiring line buffers, data is re-read from the DRAM array.

The address generator may also implement image effects in certain models of camera. For example, passport photos are generated by a manipulation of the read addresses to the DRAM. Also, image framing effects (where the central image is reduced), image warps, and kaleidoscopic effects can all be generated by manipulating the read addresses of the DRAM.

While the address generator 211 may be implemented with substantial complexity if effects are built into the standard chip, the chip area required for the address generator is small, as it consists only of address counters and a moderate amount of random logic.

A color interpolator 214 converts the interleaved pattern of red, 2.times.green, and blue pixels into RGB pixels. It consists of three 8 bit adders and associated registers. The divisions are by either 2 (for green) or 4 (for red and blue) so they can be implemented as fixed shifts in the output connections of the adders.

A convolver 215 is provided as a sharpening filter which applies a small convolution kernel (5.times.5) to the red, green, and blue planes of the image. The convolution kernel for the green plane is different from that of the red and blue planes, as green has twice as many samples. The sharpening filter has five functions:

To improve the color interpolation from the linear interpolation provided by the color interpolator, to a close approximation of a sinc interpolation.

To compensate for the image `softening` which occurs during digitization.

To adjust the image sharpness to match average consumer preferences, which are typically for the image to be slightly sharper than reality. As the single use camera is intended as a consumer product, and not a professional photographic products, the processing can match the most popular settings, rather than the most accurate.

To suppress the sharpening of high frequency (individual pixel) noise. The function is similar to the `unsharp mask` process.

To antialias Image Warping.

These functions are all combined into a single convolution matrix. As the pixel rate is low (less than 1 Mpixel per second) the total number of multiplies required for the three color channels is 56 million multiplies per second. This can be provided by a single multiplier. Fifty bytes of coefficient ROM are also required.

A color ALU 113 combines the functions of color compensation and color space conversion into the one matrix multiplication, which is applied to every pixel of the frame. As with sharpening, the color correction should match the most popular settings, rather than the most accurate.

A color compensation circuit of the color ALU provides compensation for the lighting of the photo. The vast majority of photographs are substantially improved by a simple color compensation, which independently normalizes the contrast and brightness of the three color components.

A color look-up table (CLUT) 212 is provided for each color component. These are three separate 256.times.8 SRAMs, requiring a total of 6,144 bits. The CLUTs are used as part of the color correction process. They are also used for color special effects, such as stochastically selected "wild color" effects.

A color space conversion system of the color ALU converts from the RGB color space of the image sensor to the CMY color space of the printer. The simplest conversion is a 1's complement of the RGB data. However, this simple conversion assumes perfect linearity of both color spaces, and perfect dye spectra for both the color filters of the image sensor, and the ink dyes. At the other extreme is a tri-linear interpolation of a sampled three dimensional arbitrary transform table. This can effectively match any non-linearity or differences in either color space. Such a system is usually necessary to obtain good color space conversion when the print engine work on the color electrophotographic principle.

However, since the non-linearity of a halftoned ink jet output is very small, a simpler system can be used. A simple matrix multiplier can provide excellent results. This requires nine multiplications and six additions per contone pixel. However, since the contone pixel rate is low (less than 1 Mpixel/sec) these operations can share a single multiplier and adder. The multiplier and adder are used in a color ALU which is shared with the color compensation function.

Digital halftoning can be performed as a dispersed dot ordered dither using a stochastic optimized dither cell. A halftone matrix ROM 116 is provided for storing dither cell coefficients. A dither cell size of 32.times.32 is adequate to ensure that the cell repeat cycle is not visible. The three colors--cyan, magenta, and yellow--are all dithered using the same cell, to ensure maximum co-positioning of the ink dots. This minimizes `muddying` of the mid-tones which results from bleed of dyes from one dot to adjacent dots while still wet. The total ROM size required is 1 KByte, as the one ROM is shared by the halftoning units for each of the three colors.

The digital halftoning used is dispersed dot ordered dither with stochastic optimized dither matrix. While dithering does not produce an image quite as `sharp` as error diffusion, it does produce a more accurate image with fewer artifacts. The image sharpening produced by error diffusion is artificial, and less controllable and accurate than `unsharp mask` filtering performed in the contone domain. The high print resolution (1,600 dpi.times.1,600 dpi) results in excellent quality when using a well formed stochastic dither matrix.

Digital halftoning is performed by a digital halftoning unit 217 using a simple comparison between the contone information from the DRAM 210 and the contents of the dither matrix 216. During the halftone process, the resolution of the image is changed from the 250 dpi of the captured contone image to the 1,600 dpi of the printed image. Each contone pixel is converted to an average of 40.96 halftone dots.

The ICP incorporates a 16 bit microcontroller CPU core 219 to run the miscellaneous camera functions, such as reading the buttons, controlling the motor and solenoids, setting up the hardware, and authenticating the refill station. The processing power required by the CPU is very modest, and a wide variety of processor cores can be used. As the entire CPU program is run from a small ROM 220. Program compatibility between camera versions is not important, as no external programs are run. A 2 Mbit (256 Kbyte) program and data ROM 220 is included on chip. Most of this ROM space is allocated to data for outline graphics and fonts for specialty cameras. The program requirements are minor. The single most complex task is the encrypted authentication of the refill station. The ROM requires a single transistor per bit.

A Flash memory 221 may be used to store a 128 bit authentication code. This provides higher security than storage of the authentication code in ROM, as reverse engineering can be made essentially impossible. The Flash memory is completely covered by third level metal, making the data impossible to extract using scanning probe microscopes or electron beams. The authentication code is stored in the chip when manufactured. At least two other Flash bits are required for the authentication process: a bit which locks out reprogramming of the authentication code, and a bit which indicates that the camera has been refilled by an authenticated refill station. The flash memory can also be used to store FPN correction data for the imaging array. Additionally, a phase locked loop resealing parameter is provided for scaling the clocking cycle to an appropriate correct time. The clock frequency does not require crystal accuracy since no date functions are provided. To eliminate the cost of a crystal, an on chip oscillator with a phase locked loop 224 is used. As the frequency of an on-chip oscillator is highly variable from chip to chip, the frequency ratio of the oscillator to the PLL is digitally trimmed during initial testing. The value is stored in Flash memory 221. This allows the clock PLL to control the ink-jet heater pulse width with sufficient accuracy.

A scratchpad SRAM is a small static RAM 222 with a 6T cell. The scratchpad provided temporary memory for the 16 bit CPU. 1024 bytes is adequate.

A printhead interface 223 formats the data correctly for the printhead. The printhead interface also provides all of the timing signals required by the printhead. These timing signals may vary depending upon temperature, the number of dots printed simultaneously, the print medium in the print roll, and the dye density of the ink in the print roll.

The following is a table of external connections to the printhead interface:

Connection Function Pins DataBits[0-7] Independent serial data to the eight segments of the printhead 8 BitClock Main data clock for the printhead 1 ColorEnable[0-2] Independent enable signals for the CMY actuators, allowing different 3 pulse times for each color. BankEnable[0-1] Allows either simultaneous or interleaved actuation of two banks of 2 nozzles. This allows two different print speed/power consumption tradeoffs NozzleSelect[0-4] Selects one of 32 banks of nozzles for simultaneous actuation 5 ParallelXferClock Loads the parallel transfer register with the data from the shift registers 1 Total 20

The printhead utilized is composed of eight identical segments, each 1.25 cm long. There is no connection between the segments on the printhead chip. Any connections required are made in the external TAB bonding film, which is double sided. The division into eight identical segments is to simplify lithography using wafer steppers. The segment width of 1.25 cm fits easily into a stepper field. As the printhead chip is long and narrow (10 cm.times.0.3 mm), the stepper field contains a single segment of 32 printhead chips. The stepper field is therefore 1.25 cm.times.1.6 cm. An average of four complete printheads are patterned in each wafer step.

A single BitClock output line connects to all 8 segments on the printhead. The 8 DataBits lines lead one to each segment, and are clocked in to the 8 segments on the printhead simultaneously (on a BitClock pulse). For example, dot 0 is transferred to segment.sub.0, dot 750 is transferred to segment.sub.1, dot 1500 to segment.sub.2 etc simultaneously.

The ParallelXferClock is connected to each of the 8 segments on the printhead, so that on a single pulse, all segments transfer their bits at the same time.

The NozzleSelect, BankEnable and ColorEnable lines are connected to each of the 8 segments, allowing the printhead interface to independently control the duration of the cyan, magenta, and yellow nozzle energizing pulses. Registers in the Print Head Interface allow the accurate specification of the pulse duration between 0 and 6 ms, with a typical duration of 2 ms to 3 ms.

A parallel interface 125 connects the ICP to individual static electrical signals. The CPU is able to control each of these connections as memory mapped I/O via a low speed bus.

The following is a table of connections to the parallel interface:

Connection Direction Pins Paper transport stepper motor Output 4 Capping solenoid Output 1 Copy LED Output 1 Photo button Input 1 Copy button Input 1 Total 8

A serial interface is also included to allow authentication of the refill station. This is included to ensure that the cameras are only refilled with paper and ink at authorized refill stations, thus preventing inferior quality refill industry from occurring. The camera must authenticate the refill station, rather than the other way around. The secure protocol is communicated to the refill station via a serial data connection. Contact can be made to four gold plated spots on the ICP/printhead TAB by the refill station as the new ink is injected into the printhead.

Seven high current drive transistors e.g. 227 are required. Four are for the four phases of the main stepper motor two are for the guillotine motor, and the remaining transistor is to drive the capping solenoid. These transistors are allocated 20,000 square microns (600,000 F) each. As the transistors are driving highly inductive loads, they must either be turned off slowly, or be provided with a high level of back EMF protection. If adequate back EMF protection cannot be provided using the chip process chosen, then external discrete transistors should be used. The transistors are never driven at the same time as the image sensor is used. This is to avoid voltage fluctuations and hot spots affecting the image quality. Further, the transistors are located as far away from the sensor as possible.

A standard JTAG (Joint Test Action Group) interface 228 is included in the ICP for testing purposes and for interrogation by the refill station. Due to the complexity of the chip, a variety of testing techniques are required, including BIST (Built In Self Test) and functional block isolation. An overhead of 10% in chip area is assumed for chip testing circuitry for the random logic portions. The overhead for the large arrays (the image sensor and the DRAM) is smaller.

The JTAG interface is also used for authentication of the refill station. This is included to ensure that the cameras are only refilled with quality paper and ink at a properly constructed refill station, thus preventing inferior quality refills from occurring. The camera must authenticate the refill station, rather than vice versa. The secure protocol is communicated to the refill station during the automated test procedure. Contact is made to four gold plated spots on the ICP/printhead TAB by the refill station as the new ink is injected into the printhead.

FIG. 16 illustrates rear view of the next step in the construction process whilst FIG. 17 illustrates a front camera view.

Turning now to FIG. 16, the assembly of the camera system proceeds via first assembling the ink supply mechanism 40. The flex PCB is interconnected with batteries only one of which is shown at 84, which are inserted in the middle portion of a print roll 85 which is wrapped around a plastic former 86. An end cap 89 is provided at the other end of the print roll 85 so as to fasten the print roll and batteries firmly to the ink supply mechanism.

The solenoid coil is interconnected (not shown) to interconnects 97, 98 (FIG. 8) which include leaf spring ends for interconnection with electrical contacts on the Flex PCB so as to provide for electrical control of the solenoid.

Turning now to FIGS. 17-19 the next step in the construction process is the insertion of the relevant gear chains into the side of the camera chassis. FIG. 17 illustrates a front camera view, FIG. 18 illustrates a back side view and FIG. 19 also illustrates a back side view. The first gear chain comprising gear wheels 22, 23 are utilized for driving the guillotine blade with the gear wheel 23 engaging the gear wheel 65 of FIG. 8. The second gear chain comprising gear wheels 24, 25 and 26 engage one end of the print roller 61 of FIG. 8. As best indicated in FIG. 18, the gear wheels mate with corresponding buttons on the surface of the chassis with the gear wheel 26 being snap fitted into corresponding mating hole 27.

Next, as illustrated in FIG. 20, the assembled platen unit is then inserted between the print roll 85 and aluminum cutting blade 43.

Turning now to FIG. 21, by way of illumination, there is illustrated the electrically interactive components of the camera system. As noted previously, the components are based around a Flex PCB board and include a TAB film 58 which interconnects the printhead 102 with the image sensor and processing chip 51. Power is supplied by two AA type batteries 83, 84 and a paper drive stepper motor 16 is provided in addition to a rotary guillotine motor 17.

An optical element 31 is provided for snapping into a top portion of the chassis 12. The optical element 31 includes portions defining an optical view finder 32, 33 which are slotted into mating portions 35, 36 in view finder channel 37. Also provided in the optical element 31 is a lensing system 38 for magnification of the prints left number in addition to an optical pipe element 39 for piping light from the LED 5 for external display.

Turning next to FIG. 22, the assembled unit 90 is then inserted into a front outer case 91 which includes button 4 for activation of printouts.

Turning now to FIG. 23, next, the unit 92 is provided with a snap-on back cover 93 which includes a slot 6 and copy print button 7. A wrapper label containing instructions and advertising (not shown) is then wrapped around the outer surface of the camera system and pinch clamped to the cover by means of clamp strip 96 which can comprise a flexible plastic or rubber strip.

Subsequently, the preferred embodiment is ready for use as a one time use camera system that provides for instant output images on demand.

It will be evident that the preferred embodiment further provides for a refillable camera system. A used camera can be collected and its outer plastic cases removed and recycled. A new paper roll and batteries can be added and the ink cartridge refilled. A series of automatic test routines can then be carried out to ensure that the printer is properly operational. Further, in order to ensure only authorised refills are conducted so as to enhance quality, routines in the on-chip program ROM can be executed such that the camera authenticates the refilling station using a secure protocol. Upon authentication, the camera can reset an internal paper count and an external case can be fitted on the camera system with a new outer label. Subsequent packing and shipping can then take place.

It will be further readily evident to those skilled in the art that the program ROM can be modified so as to allow for a variety of digital processing routines. In addition to the digitally enhanced photographs optimized for mainstream consumer preferences, various other models can readily be provided through mere re-programming of the program ROM. For example, a sepia classic old fashion style output can be provided through a remapping of the color mapping function. A further alternative is to provide for black and white outputs again through a suitable color remapping algorithm. Minimumless color can also be provided to add a touch of color to black and white prints to produce the effect that was traditionally used to colorize black and white photos. Further, passport photo output can be provided through suitable address remappings within the address generators. Further, edge filters can be utilized as is known in the field of image processing to produce sketched art styles. Further, classic wedding borders and designs can be placed around an output image in addition to the provision of relevant clip arts. For example, a wedding style camera might be provided. Further, a panoramic mode can be provided so as to output the well known panoramic format of images. Further, a postcard style output can be provided through the printing of postcards including postage on the back of a print roll surface. Further, clip arts can be provided for special events such as Halloween, Christmas etc. Further, kaleidoscopic effects can be provided through address remappings and wild color effects can be provided through remapping of the color lookup table. Many other forms of special event cameras can be provided for example, cameras dedicated to the Olympics, movie tie-ins, advertising and other special events.

The operational mode of the camera can be programmed so that upon the depressing of the take photo a first image is sampled by the sensor array to determine irrelevant parameters. Next a second image is again captured which is utilised for the output. The captured image is then manipulated in accordance with any special requirements before being initially output on the paper roll. The LED light is then activated for a predetermined time during which the DRAM is refreshed so as to retain the image. If the print copy button is depressed during this predetermined time interval, a further copy of the photo is output. After the predetermined time interval where no use of the camera has occurred, the onboard CPU shuts down all power to the camera system until such time as the take button is again activated. In this way, substantial power savings can be realized.

Ink Jet Technologies

The embodiments of the invention use an ink jet printer type device. Of course many different devices could be used. However presently popular ink jet printing technologies are unlikely to be suitable.

The most significant problem with thermal ink jet is power consumption. This is approximately 100 times that required for high speed, and stems from the energy-inefficient means of drop ejection. This involves the rapid boiling of water to produce a vapor bubble which expels the ink. Water has a very high heat capacity, and must be superheated in thermal ink jet applications. This leads to an efficiency of around 0.02%, from electricity input to drop momentum (and increased surface area) out.

The most significant problem with piezoelectric ink jet is size and cost. Piezoelectric crystals have a very small deflection at reasonable drive voltages, and therefore require a large area for each nozzle. Also, each piezoelectric actuator must be connected to its drive circuit on a separate substrate. This is not a significant problem at the current limit of around 300 nozzles per print head, but is a major impediment to the fabrication of pagewidth print heads with 19,200 nozzles.

Ideally, the ink jet technologies used meet the stringent requirements of in-camera digital color printing and other high quality, high speed, low cost printing applications. To meet the requirements of digital photography, new ink jet technologies have been created. The target features include:

low power (less than 10 Watts)

high resolution capability (1,600 dpi or more)

photographic quality output

low manufacturing cost

small size (pagewidth times minimum cross section)

high speed (<2 seconds per page).

All of these features can be met or exceeded by the ink jet systems described below with differing levels of difficulty. Forty-five different ink jet technologies have been developed by the Assignee to give a wide range of choices for high volume manufacture. These technologies form part of separate applications assigned to the present Assignee as set out in the list under the heading Cross References to Related Applications.

The ink jet designs shown here are suitable for a wide range of digital printing systems, from battery powered one-time use digital cameras, through to desktop and network printers, and through to commercial printing systems

For ease of manufacture using standard process equipment, the print head is designed to be a monolithic 0.5 micron CMOS chip with MEMS post processing. For color photographic applications, the print head is 100 mm long, with a width which depends upon the ink jet type. The smallest print head designed is covered in U.S. patent application Ser. No. 09/112,764, which is 0.35 mm wide, giving a chip area of 35 square mm. The print heads each contain 19,200 nozzles plus data and control circuitry.

Ink is supplied to the back of the print head by injection molded plastic ink channels. The molding requires 50 micron features, which can be created using a lithographically micromachined insert in a standard injection molding tool. Ink flows through holes etched through the wafer to the nozzle chambers fabricated on the front surface of the wafer. The print head is connected to the camera circuitry by tape automated bonding.

Tables of Drop-on-Demand Ink Jets

The present invention is useful in the field of digital printing, in particular, ink jet printing. A number of patent applications in this field were filed simultaneously and incorporated by cross reference.

Eleven important characteristics of the fundamental operation of individual ink jet nozzles have been identified. These characteristics are largely orthogonal, and so can be elucidated as an eleven dimensional matrix. Most of the eleven axes of this matrix include entries developed by the present assignee.

The following tables form the axes of an eleven dimensional table of ink jet types.

Actuator mechanism (18 types)

Basic operation mode (7 types)

Auxiliary mechanism (8 types)

Actuator amplification or modification method (17 types)

Actuator motion (19 types)

Nozzle refill method (4 types)

Method of restricting back-flow through inlet (10 types)

Nozzle clearing method (9 types)

Nozzle plate construction (9 types)

Drop ejection direction (5 types)

Ink type (7 types)

The complete eleven dimensional table represented by these axes contains 36.9 billion possible configurations of ink jet nozzle. While not all of the possible combinations result in a viable ink jet technology, many million configurations are viable. It is clearly impractical to elucidate all of the possible configurations. Instead, certain ink jet types have been investigated in detail. Forty-five such inkjet types were filed simultaneously to the present application.

Other ink jet configurations can readily be derived from these forty-five examples by substituting alternative configurations along one or more of the 11 axes. Most of the forty-five examples can be made into ink jet print heads with characteristics superior to any currently available ink jet technology.

Where there are prior art examples known to the inventor, one or more of these examples are listed in the examples column of the tables below. The simultaneously filed patent applications by the present applicant are listed by USSN numbers. In some cases, a print technology may be listed more than once in a table, where it shares characteristics with more than one entry.

Suitable applications for the ink jet technologies include: Home printers, Office network printers, Short run digital printers, Commercial print systems, Fabric printers, Pocket printers, Internet WWW printers, Video printers, Medical imaging, Wide format printers, Notebook PC printers, Fax machines, Industrial printing systems, Photocopiers, Photographic minilabs etc.

The information associated with the aforementioned 11 dimensional matrix are set out in the following tables.

ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS) Description Advantages Disadvantages Examples Thermal An electrothermal Large force High power Canon Bubblejet 1979 bubble heater heats the ink generated Ink carrier limited Endo et al GB patent to above boiling Simple to water 2,007,162 point, transferring construction Low efficiency Xerox heater-in-pit significant heat to No moving High temperatures 1990 Hawkins et al the aqueous ink. A parts required U.S. Pat. No. 4,899,181 bubble nucleates Fast operation High mechanical Hewlett-Packard TIJ and quickly forms, Small chip area stress 1982 Vaught et al expelling the ink. required for Unusual materials U.S. Pat. No. 4,490,728 The efficiency of the actuator required process is low, with Large drive typically less than transistors 0.05% of the Cavitation causes electrical energy actuator failure being transformed Kogation reduces into kinetic energy bubble formation of the drop. Large print heads are difficult to fabricate Piezo- A piezoelectric Low power Very large area Kyser et al U.S. electric crystal such as lead consumption required for Pat. No. 3,946,398 lanthanum zirconate Many ink types actuator Zoltan U.S. Pat. No. (PZT) is electrically can be used Difficult to 3,683,212 activated, and either Fast operation integrate with 1973 Stemme U.S. expands, shears, or High efficiency electronics Pat. No. 3,747,120 bends to apply High voltage drive Epson Stylus pressure to the ink, transistors Tektronix ejecting drops. required U.S. Ser. No. 09/112,803 Full pagewidth print heads impractical due to actuator size Requires electrical poling in high field strengths during manufacture

ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS) Description Advantages Disadvantages Examples Electro- An electric field is Low power Low maximum Seiko Epson, Usui et all strictive used to activate consumption strain (approx. JP 253401/96 electrostriction in Many ink types 0.01%) U.S. Ser. No. 09/112,803 relaxor materials can be used Large area such as lead Low thermal required for lanthanum zirconate expansion actuator due to titanate (PLZT) or Electric field low strain lead magnesium strength Response speed is niobate (PMN). required marginal (.about.10 .mu.s) (approx. 3.5 High voltage drive V/.mu.m) can be transistors generated required without Full pagewidth difficultly print heads Does not impractical due to require actuator size electrical poling Ferro- An electric field is Low power Difficult to U.S. Ser. No. 09/112,803 electric used to induce a consumption integrate with phase transition Many ink types electronics between the can be used Unusual materials antiferroelectric Fast operation such as PLZSnT (AFE) and (<1 .mu.s) are required ferroelectric (FE) Relatively high Actuators require phase. Perovskite longitudinal a large area materials such as tin strain modified lead High efficiency lanthanum zirconate Electric field titanate (PLZSnT) strength of exhibit large strains around 3 V/.mu.m of up to 1% can be readily associated with the provided AFE to FE phase transition.

ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS) Description Advantages Disadvantages Examples Electro- Conductive plates Low power Difficult to U.S. Ser. No. 09/112,787; static are separated by a consumption operate 09/112,803 plates compressible or Many ink types electrostatic fluid dielectric can be used devices in an (usually air). Upon Fast operation aqueous application of a environment voltage, the plates The electrostatic attract each other actuator will and displace ink, normally need to causing drop be separated from ejection. The the ink conductive plates Very large area may be in a comb or required to honeycomb achieve high structure, or stacked forces to increase the High voltage drive surface area and transistors may be therefore the force. required Full pagewidth print heads are not competitive due to actuator size Electro- A strong electric Low current High voltage 1989 Saito et al, static pull field is applied to consumption required U.S. Pat. No. 4,799,068 on ink the ink, whereupon Low May be damaged 1989 Miura et al, electrostatic temperature by sparks due to U.S. Pat. No. 4,810,954 attraction air breakdown Tone-jet accelerates the ink Required field towards the print strength increases medium. as the drop size decreases High voltage drive transistors required Electrostatic field attracts dust

ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS) Description Advantages Disadvantages Examples Permanent An electromagnet Low power Complex U.S. Ser. No. 09/113,084; magnet directly attracts a consumption fabrication 09/112,779 electro- permanent magnet, Many ink types Permanent magnetic displacing ink and can be used magnetic material causing drop Fast operation such as ejection. Rare earth High efficiency Neodymium Iron magnets with a field Easy extension Boron (NdFeB) strength around 1 from single required. Tesla can be used. nozzles to High local Examples are: pagewidth print currents required Samarium Cobalt heads Copper (SaCo) and metalization magnetic materials should be used for in the neodymium long iron boron family electromigration (NdFeB, lifetime and low NdDyFeBNb, resistivity NdDyFeB, etc) Pigmented inks are usually infeasible Operating temperature limited to the Curie temperature (around 540 K.) Soft A solenoid induced Low power Complex U.S. Ser. No. 09/112,751; magnetic a magnetic field in a consumption fabrication 09/113,097; 09/113,066; core soft magnetic core Many ink types Materials not 09/112,779; 09/113,061; electro- or yoke fabricated can be used usually present in 09/112,816; 09/112,772; magnetic from a ferrous Fast operation a CMOS fab such 09/112,815 material such as High efficiency as NiFe, CoNiFe, electroplated iron Easy extension or CoFe are alloys such as from single required CoNiFe [1], CoFe, nozzles to High local or NiFe alloys. pagewidth print currents required Typically, the soft heads Copper magnetic material is metalization in two parts, which should be used for are normally held long apart by a spring. electromigration When the solenoid lifetime and low is actuated, the two resistivity parts attract, Electroplating is displacing the ink. required High saturation flux density is required (2.0-2.1 T is achievable with CoNiFe [1])

ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS) Description Advantages Disadvantages Examples Lorenz The Lorenz force Low power Force acts as a U.S. Ser. No. 09/113,099; force acting on a current consumption twisting motion 09/113,077; 09/112,818; carrying wire in a Many ink types Typically, only a 09/112,819 magnetic field is can be used quarter of the utilized. Fast operation solenoid length This allows the High efficiency provides force in a magnetic field to be Easy extension useful direction supplied externally from single High local to the print head, nozzles to currents required for example pagewidth print Copper with rare earth heads metalization permanent magnets. should be used for Only the current long carrying wire need electromigration be fabricated on the lifetime and low print-head, resistivity simplifying Pigmented inks materials are usually requirements. infeasible Magneto- The actuator uses Many ink types Force acts as a Fischenbeck, U.S. striction the giant can be used twisting motion Pat. No. 4,032,929 magnetostrictive Fast operation Unusual materials U.S. Ser. No. 09/113,121 effect of materials Easy extension such as Terfenol- such as Terfenol-D from single D are required (an alloy of terbium, nozzles to High local dysprosium and iron pagewidth print currents required developed at the heads Copper Naval Ordnance High force is metalization Laboratory, hence available should be used for Ter-Fe-NOL). For long best efficiency, the electromigration actuator should be lifetime and low pre-stressed to resistivity approx. 8 MPa. Pre-stressing may be required Surface Ink under positive Low power Requires Silverbrook, EP 0771 tension pressure is held in a consumption supplementary 658 A2 and related reduction nozzle by surface Simple force to effect patent applications tension. The surface construction drop separation tension of the ink is No unusual Requires special reduced below the materials ink surfactants bubble threshold, required in Speed may be causing the ink to fabrication limited by egress from the High efficiency surfactant nozzle. Easy extension properties from single nozzles to pagewidth print heads

ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS) Description Advantages Disadvantages Examples Viscosity The ink viscosity is Simple Requires Silverbrook, EP 0771 reduction locally reduced to construction supplementary 658 A2 and related select which drops No unusual force to effect patent applications are to be ejected. A materials drop separation viscosity reduction required in Requires special can be achieved fabrication ink viscosity electrothermally Easy extension properties with most inks, but from single High speed is special inks can be nozzles to difficult to achieve engineered for a pagewidth print Requires 100:1 viscosity heads oscillating ink reduction. pressure A high temperature difference (typically 80 degrees) is required Acoustic An acoustic wave is Can operate Complex drive 1993 Hadimioglu et al, generated and without a nozzle circuitry EUP 550,192 focussed upon the plate Complex 1993 Elrod et al, EUP drop ejection region. fabrication 572,220 Low efficiency Poor control of drop position Poor control of drop volume Thermo- An actuator which Low power Efficient aqueous U.S. Ser. No. 09/112,802; elastic relies upon consumption operation requires 09/112,778; 09/112,815; bend differential thermal Many ink types a thermal insulator 09/113,096; 09/113,068; actuator expansion upon can be used on the hot side 09/113,095; 09/112,808; Joule heating is Simple planar Corrosion 09/112,809; 09/112,780; used. fabrication prevention can be 09/113,083; 09/112,793; Small chip area difficult 09/112,794; 09/113,128; required for Pigmented inks 09/113,127; 09/112,756; each actuator may be infeasible, 09/112,755; 09/112,754; Fast operation as pigment 09/112,811; 09/112,812; High efficiency particles may jam 09/112,813; 09/112,814; CMOS the bend actuator 09/112,764; 09/112,765; compatible 09/112,767; 09/112,768 voltages and currents Standard MEMS processes can be used Easy extension from single nozzles to pagewidth print heads

ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS) Description Advantages Disadvantages Examples High CTE A material with a High force can Requires special U.S. Ser. No. 09/112,778; thermo- very high coefficient be generated material (e.g. 09/112,815; 09/113,096; elastic of thermal Three methods PTFE) 09/113,095; 09/112,808; actuator expansion (CTE) of PTFE Requires a PTFE 09/112,809; 09/112,780; such as deposition are deposition 09/113,083; 09/112,793; polytetrafluoroethylene under process, which is 09/112,794; 09/113,128; (PTFE) is used. development: not yet standard in 09/113,127; 09/112,756; As high CTE chemical vapor ULSI fabs 09/112,807; 09/112,806; materials are usually deposition PTFE deposition 09/112,820 non-conductive, a (CVD), spin cannot be heater fabricated coating, and followed with from a conductive evaporation high temperature material is PTFE is a (above 350.degree. C.) incorporated. A 50 candidate for processing .mu.m long PTFE bend low dielectric Pigmented inks actuator with constant may be infeasible, polysilicon heater insulation in as pigment and 15 mW power ULSI particles may jam Input can provide Very low power the bend actuator 180 .mu.N force and 10 consumption .mu.m deflection. Many ink types Actuator motions can be used include: Simple planar Bend fabrication Push Small chip area Buckle required for Rotate each actuator Fast operation high efficiency CMOS compatible voltages and currents Easy extension from single nozzles to pagewidth print heads

ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS) Description Advantages Disadvantages Examples Conduct- A polymer with a High force can Requires special U.S. Ser. No. 09/113,083 ive high coefficient of be generated materials polymer thermal expansion Very low power development thermo- (such as PTFE) is consumption (High CTE elastic doped with Many ink types conductive actuator conducting can be used polymer) substances to Simple planar Requires a PTFE increase its fabrication deposition conductivity to Small chip area process, which is about 3 orders of required for not yet standard magnitude below each actuator in ULSI fabs that of copper. The Fast operation PTFE deposition conducting polymer High efficiency cannot be expands when CMOS followed with resistively heated. compatible high temperature Examples of voltages and (above 350.degree. C.) conducting dopants currents processing include: Easy extension Evaporation and Carbon nanotubes from single CVD deposition Metal fibers nozzles to techniques cannot Conductive pagewidth print be used polymers such as heads Pigmented inks doped may be infeasible, polythiophene as pigment Carbon granules particles may jam the bend actuator Shape A shape memory High force is Fatigue limits U.S. Ser. No. 09/113,122 memory alloy such as TiNi available maximum number alloy (also known as (stresses of of cycles Nitinol - Nickel hundreds of Low strain (1%) is Titanium alloy MPa) required to extend developed at the Large strain is fatigue resistance Naval Ordnance available (more Cycle rate limited Laboratory) is than 3%) by heat removal thermally switched High corrosion Requires unusual between its weak resistance materials (TiNi) martensitic state and Simple The latent heat of its high stiffness construction transformation austenic state. The Easy extension must be provided shape of the actuator from single High current in its martensitic nozzles to operation state is deformed pagewidth print Requires pre- relative to the heads stressing to distort austenic shape. The Low voltage the martensitic shape change causes operation state ejection of a drop.

ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS) Description Advantages Disadvantages Examples Linear Linear magnetic Linear Magnetic Requires unusual U.S. Ser. No. 09/113,061 Magnetic actuators include the actuators can be semiconductor Actuator Linear Induction constructed with materials such as Actuator (LIA), high thrust, long soft magnetic Linear Permanent travel, and high alloys (e.g. Magnet efficiency using CoNiFe) Synchronous planar Some varieties Actuator (LPMSA), semiconductor also require Linear Reluctance fabrication permanent Synchronous techniques magnetic Actuator (LRSA), Long actuator materials such as Linear Switched travel is Neodymium iron Reluctance Actuator available boron (NdFeB) (LSRA), and the Medium force is Requires complex Linear Stepper available multi-phase drive Actuator (LSA). Low voltage circuitry operation High current operation

ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS) Description Advantages Disadvantages Examples Linear Linear magnetic Linear Magnetic Requires unusual U.S. Ser. No. 09/113,061 Magnetic actuators include the actuators can be semiconductor Actuator Linear Induction constructed with materials such as Actuator (LIA), high thrust, long soft magnetic Linear Permanent travel, and high alloys (e.g. Magnet efficiency using CoNiFe) Synchronous planar Some varieties Actuator (LPMSA), semiconductor also require Linear Reluctance fabrication permanent Synchronous techniques magnetic Actuator (LRSA), Long actuator materials such as Linear Switched travel is Neodymium iron Reluctance Actuator available boron (NdFeB) (LSRA), and the Medium force is Requires complex Linear Stepper available multi-phase drive Actuator (LSA). Low voltage circuitry operation High current operation

BASIC OPERATION MODE Description Advantages Disadvantages Examples Proximity The drops to be Very simple Requires close Silverbrook, EP 0771 printed are selected print head proximity 658 A2 and related by some manner fabrication can between the print patent applications (e.g. thermally be used head and the induced surface The drop print media or tension reduction of selection means transfer roller pressurized ink). does not need to May require two Selected drops are provide the print heads separated from the energy required printing alternate ink in the nozzle by to separate the rows of the contact with the drop from the image print medium or a nozzle Monolithic color transfer roller. print heads are difficult Electro- The drops to be Very simple Requires very Silverbrook, EP 0771 static pull printed are selected print head high electrostatic 658 A2 and related on ink by some manner fabrication can field patent applications (e.g. thermally be used Electrostatic field Tone-Jet induced surface The drop for small nozzle tension reduction of selection means sizes is above air pressurized ink). does not need to breakdown Selected drops are provide the Electrostatic field separated from the energy required may attract dust ink in the nozzle by to separate the a strong electric drop from the field. nozzle Magnetic The drops to be Very simple Requires Silverbrook, EP 0771 pull on ink printed are selected print head magnetic ink 658 A2 and related by some manner fabrication can Ink colors other patent applications (e.g. thermally be used than black are induced surface The drop difficult tension reduction of selection means Requires very pressurized ink). does not need to high magnetic Selected drops are provide the fields separated from the energy required ink in the nozzle by to separate the a strong magnetic drop from the field acting on the nozzle magnetic ink. Shutter The actuator moves High speed Moving parts are U.S. Ser. No. 09/112,818; a shutter to block (>50 kHz) required 09/112,815; 09/112,808 ink flow to the operation can be Requires ink nozzle. The ink achieved due to pressure pressure is pulsed at reduced refill modulator a multiple of the time Friction and wear drop ejection Drop timing can must be frequency. be very accurate considered The actuator Stiction is energy can be possible very low

BASIC OPERATION MODE Description Advantages Disadvantages Examples Shuttered The actuator moves Actuators with Moving parts are U.S. Ser. No. 09/113,066; grill a shutter to block small travel can required 09/112,772; 09/113,096; ink flow through a be used Requires ink 09/113,068 grill to the nozzle. Actuators with pressure The shutter small force can modulator movement need be used Friction and wear only be equal to the High speed must be width of the grill (>50 kHz) considered holes. operation can be Stiction is achieved possible Pulsed A pulsed magnetic Extremely low Requires an U.S. Ser. No. 09/112,779 magnetic field attracts an `ink energy external pulsed pull on ink pusher` at the drop operation is magnetic field pusher ejection frequency. possible Requires special An actuator controls No heat materials for both a catch, which dissipation the actuator and prevents the ink problems the ink pusher pusher from moving Complex when a drop is not construction to be ejected.

AUXILIARY MECHANISM (APPLIED TO ALL NOZZLES) Description Advantages Disadvantages Examples None The actuator directly Simplicity of Drop ejection Most ink jets, including fires the ink drop, construction energy must be piezoelectric and thermal and there is no Simplicity of supplied by bubble. external field or operation individual nozzle U.S. Ser. No. 09/112,751; other mechanism Small physical actuator 09/112,787; 09/112,802; required. size 09/112,803; 09/113,097; 09/113,084; 09/113,078; 09/113,077; 09/113,061; 09/112,816; 09/113,095; 09/112,809; 09/112,780; 09/113,083; 09/113,121; 09/113,122; 09/112,793; 09/112,794; 09/113,128; 09/113,127; 09/112,756; 09/112,755; 09/112,754; 09/112,811; 09/112,812; 09/112,813; 09/112,814; 09/112,764; 09/112,765; 09/112,767; 09/112,768; 09/112,807; 09/112,806; 09/112,820 Oscillating The ink pressure Oscillating ink Requires external Silverbrook, EP 0771 ink oscillates, providing pressure can ink pressure 658 A2 and related pressure much of the drop provide a refill oscillator patent applications (including ejection energy. The pulse, allowing Ink pressure U.S. Ser. No. 09/113,066; acoustic actuator selects higher operating phase and 09/112,818; 09/112,772; stimulation) which drops are to speed amplitude must 09/112,815; 09/113,096; be fired by The actuators be carefully 09/113,068; 09/112,808; selectively blocking may operate controlled or enabling nozzles. with much Acoustic The ink pressure lower energy reflections in the oscillation may be Acoustic lenses ink chamber achieved by can be used to must be designed vibrating the print focus the sound for head, or preferably on the nozzles by an actuator in the ink supply. Media The print head is Low power Precision Silverbrook, EP 0771 proximity placed in close High accuracy assembly 658 A2 and related proximity to the Simple print required patent applications print medium. head Paper fibers may Selected drops construction cause problems protrude from the Cannot print on print head further rough substrates than unselected drops, and contact the print medium. The drop soaks into the medium fast enough to cause drop separation.

AUXILIARY MECHANISM (APPLIED TO ALL NOZZLES) Description Advantages Disadvantages Examples Transfer Drops are printed to High accuracy Bulky Silverbrook, EP 0771 roller a transfer roller Wide range of Expensive 658 A2 and related instead of straight to print substrates Complex patent applications the print medium. A can be used construction Tektronix hot melt transfer roller can Ink can be dried piezoelectric ink jet also be used for on the transfer Any of U.S. Ser. No. proximity drop roller 09/112,751; 09/112,787; separation. 09/112,802; 09/112,803; 09/113,097; 09/113,099; 09/113,084; 09/113,066; 09/112,778; 09/112,779; 09/113,077; 09/113,061; 09/112,818; 09/112,816; 09/112,772; 09/112,819; 09/112,815; 09/113,096; 09/113,068; 09/113,095; 09/112,808; 09/112,809; 09/112,780; 09/113,083; 09/113,121; 09/113,122; 09/112,793; 09/112,794; 09/113,128; 09/113,127; 09/112,756; 09/112,755; 09/112,754; 09/112,811; 09/112,812; 09/112,813; 09/112,814; 09/112,764; 09/112,765; 09/112,767; 09/112,768; 09/112,807; 09/112,806; 09/112,820; 09/112,821 Electro- An electric field is Low power Field strength Silverbrook, EP 0771 static used to accelerate Simple print required for 658 A2 and related selected drops head separation of patent applications towards the print construction small drops is Tone-Jet medium. near or above air breakdown Direct A magnetic field is Low power Requires Silverbrook, EP 0771 magnetic used to accelerate Simple print magnetic ink 658 A2 and related field selected drops of head Requires strong patent applications magnetic ink construction magnetic field towards the print medium. Cross The print head is Does not Requires external U.S. Ser. No. 09/113,099; magnetic placed in a constant require magnet 09/112,819 field magnetic field. The magnetic Current densities Lorenz force in a materials to be may be high, current carrying integrated in the resulting in wire is used to move print head electromigration the actuator. manufacturing problems process

AUXILIARY MECHANISM (APPLIED TO ALL NOZZLES) Description Advantages Disadvantages Examples Pulsed A pulsed magnetic Very low power Complex print U.S. Ser. No. 09/112,779 magnetic field is used to operation is head construction field cyclically attract a possible Magnetic paddle, which Small print head materials pushes on the ink. A size required in print small actuator head moves a catch, which selectively prevents the paddle from moving.

AUXILIARY MECHANISM (APPLIED TO ALL NOZZLES) Description Advantages Disadvantages Examples Pulsed A pulsed magnetic Very low power Complex print U.S. Ser. No. 09/112,779 magnetic field is used to operation is head construction field cyclically attract a possible Magnetic paddle, which Small print head materials pushes on the ink. A size required in print small actuator head moves a catch, which selectively prevents the paddle from moving.

ACTUATOR AMPLIFICATION OR MODIFICATION METHOD Description Advantages Disadvantages Examples Reverse The actuator loads a Better coupling Fabrication U.S. Ser. No. 09/113,097; spring spring. When the to the ink complexity 09/113,077 actuator is turned High stress in off, the spring the spring releases. This can reverse the force/distance curve of the actuator to make it compatible with the force/time requirements of the drop ejection. Actuator A series of thin Increased travel Increased Some piezoelectric ink stack actuators are Reduced drive fabrication jets stacked. This can be voltage complexity U.S. Ser. No. 09/112,803 appropriate where Increased actuators require possibility of high electric field short circuits strength, such as due to pinholes electrostatic and piezoelectric actuators. Multiple Multiple smaller Increases the Actuator forces U.S. Ser. No. 09/113,061; actuators actuators are used force available may not add 09/112,818; 09/113,096; simultaneously to from an actuator linearly, 09/113,095; 09/112,809; move the ink. Each Multiple reducing 09/112,794; 09/112,807; actuator need actuators can be efficiency 09/112,806 provide only a positioned to portion of the force control ink flow required. accurately Linear A linear spring is Matches low Requires print U.S. Ser. No. 09/112,772 Spring used to transform a travel actuator head area for motion with small with higher the spring travel and high force travel into a longer travel, requirements lower force motion. Non-contact method of motion transformation Coiled A bend actuator is Increases travel Generally U.S. Ser. No. 09/112,815; actuator coiled to provide Reduces chip restricted to 09/112,808; 09/112,811; greater travel in a area planar 09/112,812 reduced chip area. Planar implementations implementations due to extreme are relatively fabrication easy to difficulty in fabricate. other orientations.

ACTUATOR AMPLIFICATION OR MODIFICATION METHOD Description Advantages Disadvantages Examples Flexure A bend actuator has Simple means Care must be U.S. Ser. No. 09/112,779; bend a small region near of increasing taken not to 09/113,068; 09/112,754 actuator the fixture point, travel of a bend exceed the which flexes much actuator elastic limit in more readily than the flexure area the remainder of the Stress actuator. The distribution is actuator flexing is very uneven effectively Difficult to converted from an accurately even coiling to an model with angular bend, finite element resulting in greater analysis travel of the actuator tip. Catch The actuator Very low Complex U.S. Ser. No. 09/112,779 controls a small actuator energy construction catch. The catch Very small Requires either enables or actuator size external force disables movement Unsuitable for of an ink pusher that pigmented inks is controlled in a bulk manner. Gears Gears can be used to Low force, low Moving parts U.S. Ser. No. 09/112,818 increase travel at the travel actuators are required expense of duration. can be used Several actuator Circular gears, rack Can be cycles are and pinion, ratchets, fabricated using required and other gearing standard surface More complex methods can be MEMS drive electronics used. processes Complex construction Friction, friction, and wear are possible Buckle A buckle plate can Very fast Must stay S. Hirata et al, "An Ink-jet plate be used to change a movement within elastic Head Using Diaphragm slow actuator into a achievable limits of the Microactuator", Proc. fast motion. It can materials for IBEE MEMS, Feb. 1996, also convert a high long device life pp 418-423. force, low travel High stresses U.S. Ser. No. 09/113,096; actuator into a high involved 09/112,793 travel, medium Generally high force motion. power requirement Tapered A tapered magnetic Linearizes the Complex U.S. Ser. No. 091/112,816 magnetic pole can increase magnetic construction pole travel at the expense force/distance of force. curve