Digital Camera Patent Abstract
A camera controller incorporates a microcontroller for carrying
out all controller functions. The microcontroller is operably coupled
to a reprogrammable memory in which operating commands for the specific
camera being used are stored. Thus the microcontroller can be configured
to work with a great number of different cameras and command sets,
based upon the specific camera being used. A memory that can be
used for this purpose is an electrically erasable read only memory
that, by using a programmable logic array and random access memory,
can be reprogrammed in-place. The microcontroller is operably connected
to a camera's "on/off", zoom and focus functions so that
these may be controlled via the controller. Also controlled by the
invention is the automatic iris feature of a digital camera. Digital Camera Patent Claims
What is claimed is:
1. A control apparatus for a camera having an automatic iris control
and motor-driven zoom and focus lens functions, wherein said lens
functions respond to a particular program command-set, comprising:
a reprogrammable memory in which said particular program command-set
of said camera is loaded, wherein said reprogrammable memory is
reprogrammable in-circuit and includes an erasable programmable
read-only-memory (EPROM), a random access memory (RAM) and a programmable
logic array (PAL); a microcontroller operably coupled to said memory;
said microcontroller accessing operating code in said EPROM during
a non-reprogramming mode of said EPROM and wherein said PAL shifts
said operating code and said microcontroller access to said RAM
from said EPROM during a reprogramming mode of said EPROM; a zoom
actuation switch operably coupled to said microcontroller and said
motor-driven zoom function of said camera; a focus actuation switch
operably coupled to said microcontroller and said motor-driven focus
function of said camera; a multiplying digital-to-analog converter
operably coupled to said microcontroller and to an analog-formatted
automatic iris control of said camera, said multiplying digital-to-analog
converter providing an analog control input signal to said analog-formatted
automatic iris control based upon to a user-specified command so
that said automatic iris control of said camera may be set at a
user-specified light income level; and a user-command input operably
coupled to said microcontroller wherein said user-command input
corresponds to said particular program command-set of said camera
so that said motor-driven zoom and focus functions of said camera
and said automatic iris control of said camera is controllable by
said user.
Digital Camera Patent Description
BACKGROUND OF THE INVENTION
Technological advances have made it so that many American families
and individuals can afford a digital movie camera. These cameras
are being used more and more to capture images and then transfer
these images via the Internet. Another use of the cameras is for
surveillance purposes.
Digital cameras, with motor actuated zoom and focus capabilities,
are rapidly becoming the camera of choice for a wide variety of
surveillance applications. Many of these cameras come equipped with
an automatic iris feature. The automatic iris function allows a
selected amount of light to reach the image capturing element of
the camera in a wide variety of light conditions. With this feature,
image resolution is largely preserved though ambient light conditions
may go from bright to dim and vice-versa.
Certain controllers are available for remotely operated video cameras.
These controllers are invariably specific to the make and model
of the camera and usually offer little capability to adapt to other
camera designs. Regarding automatic iris functions, the controllers
permit a remote operator to choose to activate or deactivate the
function.
With technology ever-improving in the digital camera field, it
becomes prudent and at times necessary to replace cameras being
used for their more modern successors. In such cases, the remote
controllers used with the cameras often will need to be changed
and invariably those suited for the new cameras are unique to the
camera purchased. The cost of supplying a new controller with each
change could rapidly become prohibitive.
It is therefor desirable to have a digital camera controller that
is adaptable to a wide-variety of digital cameras, foregoing the
need to replace the controller with the acquisition of every new
camera. Another desirable feature of such a controller is to provide
a remote automatic iris control that is not limited solely to actuating
or de-actuating the feature, but that allows a remote viewer to
set the automatic iris feature to remain functional at a user-specified
light level.
This latter feature will allow a user to accommodate scenes in
which a bright object appears in a dark background, or a dark object
appears in a bright background. Previous automatic iris functions
did not readily accommodate these extremes. In surveillance applications,
such tuning of the automatic iris can be crucial, as it can be envisioned
that it headlights, flares or other focused light may temporarily
blind the view of a remote observer who cannot adjust the iris.
There is thus a need for a digital camera controller that may be
used with a wide variety of cameras and that permits the automatic
iris function of those cameras to be fine tuned by a user of the
camera controller.
SUMMARY OF THE INVENTION
The invention provides a camera controller incorporating a microcontroller
for carrying out all controller functions. The microcontroller is
operably coupled to a reprogrammable memory in which operating commands
for the specific camera being used are stored. Thus the controller
of the invention can be configured to work with a great number of
different cameras and command sets, based upon the specific camera
to be controlled. An example memory that can be used for this purpose
is an electrically erasable read only memory that, by using a programmable
logic array and random access memory, can be reprogrammed in-place.
The microcontroller is operably connected to a camera's "on/off",
zoom and focus functions so that these may be controlled via the
controller. Also controlled by the invention is the automatic iris
feature of a digital camera. An exemplary embodiment of the invention
uses a multiplying digital-to-analog converter to control analog-formatted
iris control devices. The controller is also designed to be used
with cameras that utilize digital-formatted iris control devices.
In either case, the controller of the invention permits its user
to set the automatic iris to a user-specified light income level.
The automatic iris will then strive to maintain the same degree
of light exposure to its image collector according to this user-set
adjustment. Additionally, the user may elect to activate or deactivate
the iris control.
OBJECTS OF THE INVENTION
It is an object of this invention to improve remote camera control
capability.
Another object of this invention is to provide a remote camera
controller that can be used with a wide variety of cameras.
Yet another object of this invention is to provide a remote camera
controller that controls motor-driven zoom and focus functions of
the camera.
A further object of this invention is to provide a remote camera
controller that permits control and tuning of an automatic iris
feature of a camera so that the iris feature can be actuated or
de-actuated and can also be set to remain functional to provide
a user specified light income level to the image sensor of the camera.
Still a further object of this invention is to provide all of the
above objects to digital cameras.
Other objects, advantages and new features of the invention will
become apparent from the following detailed description of the invention
when considered in conjunction with the accompanied drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 illustrates an exemplary camera controller according to
a representative embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 shows a representative embodiment of the invention. Referring
to this figure, camera controller 10 includes a microcontroller
12, a multiplying digital-to-analog converter (MDAC) 14, seven solid-state
relays 16-28, flash memory 30, random-access memory (RAM) 32, a
programmable logic array (PAL) 34, and power and other standard
devices for microcontroller operation and interface, not shown.
In this example, microcontroller 12 has two serial interfaces and
an integral analog-to-digital converter.
Commercial products that may be used for these components are,
for example, a microcontroller available through Siemens as part
number SAF-C517-LM, which is similar to the popular 8051 type of
microcontroller. Multiplying analog-to-digital converter 14 is available
through Analog Devices as part number AD8320. Relays 16-28 are solid
state, available from International Rectifier as part number PVN012.
Electrically erasable read only memory (EPROM) 30 is a flash memory
available as AMD part number 29F010.
Random access memory 32 may, for example, be a Hitachi memory bearing
part number HM62256BLPI-8. Programmable logic array 34, for example,
is available through Vantis as part number PALCE16V8.
A camera that may be utilized with the invention is a Cohu Model
3522 color video camera with engineering revision ER4565HN. The
camera uses the Cohu Model 3522-1000 DSP interline transfer CCD
color camera with a 1/2 inch sensor, NTSC compatibility, and a 12-volt
DC power supply. A suitable lens is a Cohu 160 millimeter, with
motor-driven zoom and focus. Built-in potentiometers provide zoom
and focus position feedback. A similar camera is the Cohu series
1300 camera identified as the Model 1310.
Though the above cameras are described by way of example, the invention
is designed to be used with a great variety of makes and models
of cameras.
Referring once again to the figure, a utilized camera will be connected
to the invention via a number of operating lines. Line 36 is a serial
port digital interface for connecting to a camera having a digitally
formatted, such as pulse-width modulated, iris control function.
In cases in which iris control functions are of analog format, line
38 provides an analog format output from the camera, for example,
in the form of an amplitude-modulated video signal. Line 40 is an
analog control line for sending user-specified analog commands to
the analog format iris control of a camera fitted with these features.
Line 42 provides lens potentiometer feedback of the zoom and focal
length camera settings to microcontroller 12. Line 44 provides an
interface between the MDAC 14 and microcontroller 12. Line 46 is
a serial interface port into microcontroller 12 through which user-specified
commands are entered into the microcontroller.
Used in conjunction with microcontroller 12 are relays 16-28 and
appropriately coupled control lines (collectively identified as
48) from microcontroller 12 to the relays to provide a "lens
common", zoom control, focus control and an "on-off"
power capability to the camera. The EPROM 30, RAM 32 and PAL 34
are operably coupled to microcontroller 12 to provide the microcontroller
with the command programming set for the camera that is used. As
will be further discussed, PAL 34 is operably coupled to EPROM 30
and RAM 32 to permit "in-circuit" reprogramming of the
EPROM.
Operation of the camera/controller 10 interface is performed by
microcontroller 12 running firmware located in flash memory 30,
or RAM 32 when under reprogramming conditions as will be explained.
The microcontroller accepts operator commands via serial port 46
and issues camera commands via control lines 48 and serial port
36 in cameras that use digitally formatted control functions or
via control lines 48 and control line 40 in cameras using analog
formatted iris control functions.
Analog adjustment of a camera's automatic iris function is achieved
by the insertion of MDAC 14 into the feedback loop between the camera
and lens of an analog controlled camera iris function. Applying
digital commands to MDAC 14 to vary the gain of the amplifying or
attenuating stage of the iris feature has the effect of modulating
the feedback signal strength. Increasing the gain will cause the
iris to close, darkening the image, while decreasing the gain will
cause the iris to open, making the image lighter. The automatic
iris function will then continue to operate according to the user-set
light adjustment.
In a camera having a digitally controlled iris feature, the camera's
automatic iris is adjusted directly via digital commands sent from
microcontroller 12 over control line 36. As with the analog adjusted
iris, the user-specified commands are entered by way of control
line 46, where these commands are converted by microcontroller 12
according to the camera's command set loaded into the memory 50
of controller 10.
The lens drive-motors are controlled by six relays, 16-26, which
can apply positive or negative voltage to either the zoom or focus
motor and to the lens common. Power to the camera can be switched
on or off by microcontroller command through relay 28.
The microcontroller's operating program is stored as firmware in
non-volatile flash electrically erasable programmable read only
memory and can be modified remotely. This is accomplished by use
of logic which switches the microcontroller to run out of volatile
random access memory (RAM) during reprogramming. The microcontroller
can reprogram flash memory 30 by copying its operating system to
RAM 32, using PAL 34 to switch program and data memory access signals,
and by then issuing erase and program commands to the flash memory.
This microcontroller uses a memory structure know to those skilled
in the art as the "Harvard Architecture" wherein program
and data memory share the same address. For added protection during
programming, only the higher part of the flash chip is reprogrammed.
The lower part is reserved for the basic reprogramming software.
In case of error during reprogramming, the software is still able
to run out of lower memory to accept instructions to reprogram the
higher memory. An alternative in-system flash reprogramming is described
in the Siemens Semiconductor application note, AP0821 "C5XX/80C5XX"
In-System FLASH Programming". This approach can be found on
the CDROM entitled "8-bit and 16-bit Microcontrollers CD-ROM
Edition 2.0", Siemens Semiconductors, November 1997.
The advantage of allowing the Flash ROM to be reprogrammed by the
microcontroller via remote control is that a camera's firmware can
be easily modified without disassembly of the invention's hardware.
In summary, this invention provides wide flexibility as a remote
camera controller. It uses a microcontroller with two serial interfaces
to communicate simultaneously with a user and a camera. This allows
translation of commands from one camera command set to another,
so the invention can be made compatible with any digital camera
with a serial interface and any user command set.
An alternative to the described example of the invention includes
implementing the function of the MDAC using discrete components.
Similarly, the analog-to-digital conversion function of the microcontroller
may be performed by components external to the microcontroller.
Multiple power supplies can be used to reduce the number of relays,
and any type of electronic or mechanical switch can be used to perform
the relay switching function.
Depending on the microcontroller interface employed, a wide variety
of serial interfaces could meet RS232, RS422, or RS485 standards.
Obviously, many modifications and variations of the invention are
possible in light of the above teachings. It is therefore to be
understood that within the scope of the appended claims the invention
may be practiced otherwise than as has been specifically described.
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