Digital Camera Patent Abstract
A digital camera for use in a communication device in which the
image sensor is formed on a substrate and is mounted on a micro-electromechanical
system for movement relative to the camera lens to provide an autofocus
capability. In addition the lens may be mounted on a micro-electromechanical
system for movement relative to the image sensor to provide both
an autofocus and a zoom capability. Digital Camera Patent Claims
I claim:
1. A digital camera system comprising: a lens assembly mounted
for receiving an image and projecting said image on an image plane;
a micro-electromechanical (MEMS) system support mechanism for providing
at least two positions of movement to a supported element, said
MEMS support mechanism being fabricated integrally with said supported
element; and a semi-conductor image sensor mounted at said image
plane for movement on said MEMS system support mechanism and being
operatively associated with said lens assembly to generate a digital
image.
2. A digital camera system, according to claim 1, wherein said
MEMS system support mechanism is an electrostatic resonator.
3. A digital camera system, according to claim 1, wherein the image
sensor is fabricated on a silicon chip in which is imbedded control
circuitry and said MEMS system support mechanism is integrally fabricated
therewith.
4. A digital camera system, according to claim 1, wherein said
movement of said image sensor provides an auto focus function.
5. A digital camera system, according to claim 1, wherein said
lens assembly is mounted for movement on said MEMS system support
mechanism for movement relative to said image sensor and said image
sensor is fixed, said movement adapted to provide a zoom function.
6. A digital camera system, according to claim 1, further comprising:
a substrate for supporting said digital camera system; a first MEMS
fabricated on said substrate and connected to said lens assembly
for providing movement of said lens assembly between at least two
positions; a second MEMS fabricated on said substrate and connected
to said image sensor for providing movement of said image sensor
between at least two positions; and wherein said movement of said
lens system and said image sensor is relative to each other to provide
both an autofocus and zoom function.
7. A mobile communication device including a system to transmit
data over a communication network comprising: a housing containing
said system to transmit data; a lens assembly mounted within said
housing for receiving an image and projecting said image on an image
plane; a micro-electromechanical (MEMS) system support mechanism
for providing at least two positions of movement to a supported
element, said MEMS system support mechanism being fabricated integrally
with said supported element; said MEMS system support mechanism
mounted within said housing; and a semi-conductor image sensor mounted
at said image plane for movement on said MEMS system support mechanism
and being operatively associated with said lens assembly to generate
a digital image.
8. A mobile communication device including a system to transmit
data over a communication network, according to claim 7, wherein
said MEMS system support mechanism is an electrostatic resonator.
9. A mobile communication device including a system to transmit
data over a communication network, according to claim 7, wherein
the image sensor is fabricated on a silicon chip in which is imbedded
control circuitry and said MEMS system support mechanism is integrally
fabricated therewith.
10. A mobile communication device including a system to transmit
data over a communication network, according to claim 7, wherein
said movement of said image sensor provides an auto focus function.
11. A mobile communication device including a system to transmit
data over a communication network, according to claim 7, wherein
said lens assembly is mounted for movement on said MEMS system support
mechanism for movement relative to said image sensor and said image
sensor is fixed, said movement adapted to provide a zoom function.
12. A mobile communication device including a system to transmit
data over a communication network, according to claim 7, further
comprising: a substrate for supporting said digital camera system;
a first MEMS fabricated on said substrate and connected to said
lens system for providing movement of said lens system between at
least two positions; a second MEMS fabricated on said substrate
and connected to said image sensor for providing movement of said
image sensor between at least two positions; and
wherein said movement of said lens assembly and said image sensor
is relative to each other to provide both an autofocus and zoom
function.
Digital Camera Patent Description
BACKGROUND OF THE INVENTION
Mobile communications devices are becoming more compact while their
functions and features are ever expanding. As a next step in this
process of expanding applications, a digital camera may be installed.
This requires a new cycle of development with respect to the digital
camera in order to package the necessary functions within the compact
profile of the mobile communications device. In order to miniaturize
the camera for such use, the zoom feature is often eliminated or
substantially reduced in functionality. This is because the apparatus
needed to move the lens in a traditional zoom mechanism is cumbersome.
The development is facilitated by the introduction of digital, semi-conductor,
imaging sensors, such as CCD and C-MOS sensor arrays.
In addition a new class of micro-miniature components have become
available that provide the functionality of both electrical and
mechanical components. These components are fabricated in a process
similar to the manufacture of integrated circuit chips, namely the
surface treatment of silicon wafers. These mechanisms can provide
the function of sensors (resonators), actuators, transducers, motors,
and gears to high tolerances. By micro-machining silicon wafers
layered on a substrate, the components, of the so called micro-electromechanical
system (MEMS), are constructed on a thin substrate. A description
of MEMS components is contained in Philosophical Transactions of
the Royal Society: Physical Sciences and Engineering, Series A,
Issue No. 1703, Dec. 15, 1995, pp. 355-366, which is incorporated
herein by reference.
It is a purpose of this invention to provide an autofocus and zoom
system for a compact electronic device. A further purpose of this
invention is to provide these functions by using a sensor array,
such as a C-MOS sensor array, and a lens actuation mechanism suitable
for fabrication on a silicon wafer. It is a further purpose of this
invention to utilize the advantages of micro-electromechanical system
(MEMS) manufacturing techniques to obtain these goals.
SUMMARY OF THE INVENTION
A miniaturized digital camera is constructed for use with a mobile
communication device or other compact appliance. The optical system
of the camera consists of a small lens system having the traditional
components of a primary lens, a variator lens, and a compensator
lens. The lens system transmits the image received from an external
source to a sensor array. The sensor array is constructed on a substrate
using silicon wafer fabrication techniques and is positioned to
receive the image from the lens system. The array is operatively
associated with a micro-electro mechanical component for movement
between at least two positions by actuation of the MEMS component.
Both the array and the MEMS component are constructed on the same
substrate utilizing similar techniques to create an extremely small
fully functional imaging system for use with the lens system. Actuation
of the MEMS component, will move the sensor array relative to the
lens system. Such actuation of the MEMS component, can be accomplished
in response to, for example, the sensed distance of the lens system
from the subject of the image. In this manner an autofocus function
can be accomplished. The movement of the sensor is combined with
a coordinated movement of the variator and/or compensator lenses
to provide a zoom function. To facilitate this coordinated movement
one or both of these lens can be mounted for movement on the MEMS
component in operative association with the sensor array. Since
the position of the sensor array can be varied the movement of the
lens-system/lenses could in some cases be reduced. With a suitable
lens design and by moving the sensor array itself, it could e.g.
be possible to reduce or completely omit the movement of one of
the lenses, e.g. the compensator. In this manner a variety of configurations
can be accomplished to provide the zoom and autofocus functions
in a miniaturized version of the traditional system.
DESCRIPTION OF THE DRAWING
The subject invention is described in more detail below with reference
to the drawing in which:
FIG. 1a is a schematic illustration of a traditional lens system
with a fixed sensor array;
FIG. 1b is a schematic illustration of a lens system in which the
sensor array is mounted for movement;
FIG. 2 is a schematic illustration of the sensor array of this
invention fabricated with the MEMS component for multiple positions;
FIG. 3 is a schematic illustration of the sensor array and lens
system fabricated and mounted for coordinated movement on the MEMS
component; and
FIGS. 4a, 4b, 4c and 4d are schematic illustrations of a traditional
lens system, showing the various relative positions of the lenses.
DETAILED DESCRIPTION OF THE INVENTION
A typical optical lens system 1 for a camera having autofocus and
zoom capability is depicted schematically in FIGS. 4a-4d. It generally
will consists of a primary lens 2, a variator lens 3, and a compensator
lens 4 which are operatively associated to project a focused image
on image plane 5. As shown, the lens has three "principal"
positions, i.e., wide angle, middle and telephoto. The zoom function,
as shown in FIG. 4d, can be a smooth movement between the two end
positions (wide and tele), as indicated by arrow 30, and do not
necessary have to be a stepwise action with only three options.
These variations in function are provided by moving the variator
and compensator lens, 3 and 4 respectively, as shown. Lens system
1 is used in a digital camera 6, as shown in FIG. 1, in which the
lens system 1 is secured within a housing (not shown) to project
an image on an image sensor 7 positioned at the image plane 5 of
the camera 6. The assembly of lens are adjusted, as shown in FIGS.
4a-4d to obtain autofocus and zoom functions.
In accordance with this invention, the mechanical movement of the
lens system 1 is constructed through the use of advanced micro-machining
techniques. Through such techniques, a semi-conductor image sensor
can be combined with a lens system in a unique manner to obtain
substantially the same functions as described above. The resulting
image generating system can be exceedingly small and therefore can
be conveniently packaged within the confines of a mobile communications
device, such as a cellular telephone. As shown in FIG. 1b, a semi-conductor
image sensor 9 is supported for movement by a micro-machined actuator
assembly 10 in operative association with lens system 8 and positioned
within the housing 11 of a digital camera or mobile communication
device.
The actuating assembly 10 of the digital camera is shown in more
detail in FIG. 2. In the actuating assembly 10, an image sensor
13 is constructed with its associated electronics on a semi-conductor
chip 14. Terminal 15 provides the sensor 13 with appropriate electrical
contact to power the sensor 13. A micro-electrical mechanical system
(MEMS) 16 is formed on substrate 17 to support the sensor 13. MEMS
16 may take many different forms depending on the function of the
camera and the fabricating technique used. For the purpose of illustration,
a series of electrostatic resonators 18 are schematically shown.
Electrostatic resonator 18 is an example of a linear actuator which
can be used as a precise positioner, among other things. Actuator
18 consists of a pair of bases 19 which are fixed to the substrate
17 and moveable supports 20. Supports 20 are connected to bases
19 by means of electrostatic fingers 21. Sensor chip 13 is connected
to movable supports 20 by a further pair of electrostatic fingers
22. The moveable supports 20 and the sensor chip 13 can be moved
by applying a voltage between the moveable structure and its immediately
adjacent supporting structure. For this purpose contacts 23 are
provided on moveable support 20 and contacts 24 are provided on
bases 19. The actuating assembly 10, as shown in FIG. 2, provides
a two position motion utilizing the movement of moveable supports
20 on their associated bases 19 and the movement of the sensor 13
on supports 20. Further information with respect to MEMS is available
from several sources, in particular, the MEMS and Nanotechnology
Exchange, 1895 Preston White Drive, Suite 100, Reston, Va., 20191
and the University of Wisconsin Engineering Department.
Since, as shown in FIG. 2, the sensor 13 is shown mounted on the
substrate 17, this particular embodiment could be adapted to provide
autofocus, if used within a conventional lens system. If however
the sensor 13 was mounted on the substrate 17 (see phantom lines
12) and replaced by a lens mounted on the illustrated support assembly,
a zoom mechanism could be provided.
In the alternate embodiment shown in FIG. 3, a MEMS support assembly
is shown which may be adapted to provide both autofocus and zoom
functions. In this embodiment, a lens 24 is mounted on a three position
(or smoothly variable) MEMS support assembly 25 to the substrate
26 through base element 27. An image sensor 28 is also mounted for
independent motion on a two position MEMS support 29. This system
may be adapted to provide both an autofocus and a zoom capability.
The image sensor used herein is a semiconductor C-MOS sensor array
constructed using standard silicon processing techniques which are
compatible with the MEMS fabrication process. In addition appropriate
electronic or manual systems would be connected to initiate operation
of the functions provided. Ideally the sensor array is constructed
on a chip with imbedded control circuitry including sensors, memory,
and other functions.
The MEMS technique used may be surface micro-machining. This method
is an additive fabrication technique which involves the building
of the device on top of the supporting substrate. The substrate
would be constructed with the necessary imbedded control circuitry,
for example as an application specific semi-conductor integrated
circuit. In this way the digital image sensor and the micro-electromechanical
zoom are manufactured on the same chip using silicon based microelectronics
for the sensor and micromachining technology for the micro-electromechanical
support.
In this manner a micro-miniature digital camera having a variety
of basic functions can be fabricated in a cost effective manner
for use with a mobile communication device.
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