JPH03235586A - Processing unit for image sensor - Google Patents

Abstract

PURPOSE:To always obtain an accurate image signal by applying correction to an image sensor output while taking ambient temperature and storage time as parameters. CONSTITUTION:A temperature area is divided into four cases; below 20 deg.C, 20 deg.C-30 deg.C, 30 deg.C-40 deg.C, and 40 deg.C or over, referred to as A-D, and a coefficient of the normal temperature area B is set to 1. When a coefficient of the area A is obtained, the ratio of a picture element output of the center temperature of 0 deg.C of the area A to the picture element output of room temperature of 25 deg.C is calculated and the ratio is used for the coefficient of the area A. Coefficients of the areas C, D are obtained similarly. The coefficient is multiplied with a dark correction data to calculate a picture element output suitable for each temperature area and the calculated picture element output is used as a dark correction data and the value is subtracted later from the image signal. Thus, even when the picture element output when no light strikes on the sensor is fluctuated by temperature, the case is coped with.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image signal processing device stored in an image sensor.

[Prior art]

Conventionally, in image sensors such as CCDs that accumulate incident light and output image signals, there are manufacturing errors in the sensor solid state, and even if the same light enters each pixel of the sensor, the output of each pixel will not match. Things were happening that shouldn't happen.

Therefore, the output of each pixel when the sensor is not irradiated with light or the output of each pixel when uniform light is irradiated is determined in advance, and these data are used as parameters to determine the output of each pixel of the sensor. A method is being taken to correct this.

[Problem that the invention is trying to solve]

However, in addition to the above-mentioned pixel output errors, image sensors also have temperature-related errors and errors that occur due to accumulation time. If they were different, accurate output could not be obtained.

[Means to solve the problem]

The present invention has been made in view of the above-mentioned matters, and is an image sensor that detects the actual accumulation time in the image sensor and corrects the output of the image sensor using the accumulation time as a factor, thereby eliminating the above-mentioned disadvantages. -Provides processing equipment.

A further object of the present invention is to provide an image sensor processing device that eliminates the above-mentioned disadvantages by detecting the temperature of the image sensor when it is in use and correcting the output of the image sensor using the temperature as a factor.

〔Example〕

FIG. 3 is a diagram showing a schematic configuration of a focus detection device for realizing the above embodiment.

In the figure, MSK is a field mask, with a cross-shaped opening MSK-1 in the center and vertical openings MSK-2 at the periphery on both sides.
, MSK-3.

FLDL is a field lens, which has three parts FLDL-1, FLDL-2, FLDL corresponding to the three openings MSK-1, MSK-2°MSK-3 of the field mask.
-3. DP is a diaphragm, and there are a total of four openings DP-1a and DP-1b in the center, one pair each on the top, bottom, left and right.
.

DP-4a, DP-4b, and a pair of two openings DP-2a, DP-2b and DP-3a in the left and right peripheral parts,
DP-3b is provided respectively. Each area FLDL-1, FLDL-2 of the field lens FLDL,
FLDL-3 has these aperture pairs DP-1 and DP, respectively.
It has the function of forming an image of -2°DP-3 near the exit pupil of an objective lens (not shown). AFL has 4 pairs of lenses in total AFL-1a, AFL-1b, AFL-4a, AFL-
4b, AFL-2a, AFL2b, AFL-3a, AF
This is a secondary imaging lens consisting of L-3b, and is arranged behind each aperture of the aperture DP, corresponding to each aperture. SNS has 4 pairs of 8 sensor rows 5NS-1a and 5NS-1b.

5NS-4a, 5NS-4b, 5NS-2aS
The sensor is composed of NS-2b, 5NS-3a, and 5NS-3b, and is arranged so as to correspond to each secondary imaging lens AFL and receive its image. Multiple pairs of sensors detect the focus state of each different area. Note that each area is referred to as a distance measurement point.

In the focus detection system shown in Fig. 3, when the focal point of the photographing lens is in front of the film plane, the subject images formed on each pair of sensor rows are close to each other, and when the focal point is behind the film plane, the subject images are close to each other. In this case, the subject images are separated from each other. This amount of relative positional displacement of the subject image has a specific functional relationship with the amount of defocus of the photographing lens, so if appropriate calculations are performed on the sensor outputs of each pair of sensor rows, the amount of defocus of the photographing lens, It is possible to detect the so-called defocus amount.

By adopting the configuration described above, it is possible to measure even objects whose light intensity distribution changes only in one direction, vertically or horizontally, near the center of the range photographed or observed by an objective lens (not shown). It becomes possible to distance the opening MSK-2, MSK on the week side of the field mask other than the center.
It is also possible to measure the distance to an object located at a position corresponding to -3.

FIG. 4 shows the arrangement when the focus detection device having the focus detection system shown in FIG. 3 is housed in a camera.

In the figure, LMS is a zoom shooting lens, QRM is a quick return mirror, FSCRN is a focus plate, PP is a pentalism, EPL is an eyepiece, FPLN is a film surface, and SM
is the submirror MSK is the field mask, ICF is the infrared cut filter, FEDL is the field lens, RMI, RM
2 is the first. A second reflection mirror, SHMSK is a light-shielding mask, DP is an aperture, AFL is a secondary imaging lens, AFP is a prism member having a reflection surface AFP-1 and an exit surface AFP-2, and SNS is a cover glass 5NSCG and a light-receiving surface 5NSP.
This is a sensor with LN. Prism members A, F
P is a reverse slope AFP- which has a metal reflective film such as aluminum deposited on it.
1, and has the function of reflecting the light beam from the secondary imaging lens AFL and deflecting it to the exit surface AFP-2.

FIG. 2 is a circuit diagram showing an example of a specific configuration of a camera equipped with a focus detection device as shown in FIGS. 3 and 4. First, the configuration of each part will be explained.

In FIG. 2, PH3 is a camera control device, for example, a CPU (central processing unit) inside.

It is a one-chip microcomputer (hereinafter referred to as microcomputer) having ROM RA, M, and A/D conversion functions. The microcomputer PR8 performs a series of camera operations such as an automatic exposure control function, an automatic focus adjustment function, and film winding and rewinding according to a camera sequence program stored in the ROM. For this purpose, the microcomputer PRS uses communication signals 5o-3I, 5CLK, and communication selection signal CLCM.

The C3DR and CDDR are used to communicate with peripheral circuits within the camera body and a control device within the lens to control the operation of each circuit and lens.

SO is the data signal output from microcomputer PR3, SI
is a data signal input to the microcomputer PR3, and 5CLK is a synchronization clock for the signals So and Sl.

LCM is a 1nons communication buffer circuit, and when the camera is in operation, it supplies power to the lens power supply terminal VL, and the selection signal CLCM from the microcomputer PR8 is at a high potential level (hereinafter referred to as "H", low potential The level is “L”
”), it becomes a communication buffer between the camera and lens.

The microcomputer PR3 sets the selection signal CLCM to “H” and
When predetermined data is sent out as a signal SO in synchronization with CLK, the buffer circuit LCM transmits each buffer signal LCK, 5CLKSO via the camera-lens communication contact.
Output DCL to the lens. At the same time, the lens LNS
The buffer signal of the signal DLC from the microcomputer PR8 is outputted as the signal Sl, and the microcomputer PR8 inputs the signal Sl as lens data in synchronization with 5CLK.

DDR is a switch detection and display circuit, and the signal CD
Selected when DR is H″, SO.

Controlled by microcomputer PR3 using SI 5CLK. That is, the display on the camera's display member DSP is switched based on the data sent from the microcomputer PR8,
The on/off states of various operating members of the camera are notified to the microcomputer PR3 by communication.

SWI and SW2 are switches that are linked to a release button (not shown), and when the release button is pressed in the first step, SW is activated.
I is turned on, and then SW2 is turned on at the second stage of depression. The microcomputer PR8 performs photometry and automatic focus adjustment when SW1 is turned on, and uses SW2 as a trigger to control exposure and subsequently advance the film.

Note that the switch SW2 is connected to the "interrupt input terminal" of the microcomputer PH1, and even if a program is being executed when SW1 is on, an interrupt is generated by turning on SW2, and control can be immediately transferred to a predetermined interrupt program.

MTRI is for film feeding, MTR2 is for mirror up/
This is a motor for down and shutter charging, and forward and reverse rotation is controlled by respective drive circuits MDRI and MDR2. Microcomputer PR8 to MDRI, MDR2
Signals input to MIF, MIR, M2F, M2R
is a signal for motor control.

MCI and MG2 are magnets for starting the movement of the front and rear shutter curtains, respectively, and are energized by the signal SMGI and the 5MG2° amplification transistors TRI and TR2, and the shutter control is performed by the microcomputer PR3.

In addition, switch detection and display circuit DDR.

Motor drive circuit MDRI, MDR2, shutter control are as follows:
Since this is not directly related to the present invention, detailed explanation will be omitted.

LPR8 is an in-lens control circuit, and the circuit LPR81:
Signal D CL +' input in synchronization with L CK! ,
This is data of a command from the camera to the photographic lens LNS, and the operation of the lens in response to the command is determined in advance.

The control circuit LPR8 analyzes the command according to a predetermined procedure, and determines the operation of focus adjustment and aperture control, and the operation status of each part of the lens (driving status of the focusing optical system, driving status of the diaphragm, etc.) and various parameters from the output DLC. (Open F number, focal length, coefficient of defocus amount vs. movement amount of the focusing optical system, etc.) are output.

This embodiment shows an example of a zoom lens, and when a focus adjustment command is sent from a camera, the focus adjustment motor LTMR is activated according to the driving amount and direction sent at the same time.
is driven by the signal LMF LMR to move the point adjustment optical system in the optical axis direction to perform focus adjustment. The amount of movement of the optical system is determined by a pulse signal 5E of an encoder circuit ENCF that detects the pattern of a pulse plate that rotates in conjunction with the optical system using a photocoupler and outputs a number of pulses according to the amount of movement.
It is monitored by the NCF and counted by the counter in the circuit LPR8, and when the counter value matches the movement amount sent to the circuit LPRS, the LPR3 itself sets the signals LMF and LMR to "L".
to control motor LMTR.

Therefore, once the focus adjustment command is sent from the camera, the microcomputer PR3, which is the camera control device, does not need to be involved in lens driving at all until the lens driving is completed. Furthermore, the configuration is such that it is possible to send the contents of the counter to the camera if there is a request from the camera.

When an aperture control command is sent from the camera, a stepping motor DMTR, which is known for driving an aperture, is driven in accordance with the number of aperture stages sent at the same time. Note that since the stepping motor can be controlled in an open manner, it does not require an encoder to monitor its operation.

ENCZ is an encoder circuit attached to the zoom optical system, and circuit LPR8 inputs signal 5ENCZ from encoder circuit ENCZ to detect the zoom position. Lens parameters at each zoom position are stored in the control circuit LPR3, and when a request is received from the camera-side microcomputer PR3, parameters corresponding to the current zoom position are sent to the camera.

TEMP is a temperature detection circuit that detects the temperature of the camera, and its output STMP is input to the analog input terminal of the microcomputer PRS, and after A/D conversion, is used to control temperature correction according to a predetermined program.

The SPC receives light from a subject via a photographic lens. It is a photometric sensor for exposure control, and its output is 5SPC.
is input to the analog input terminal of microcomputer PR8, and A/
After D conversion, it is used for automatic exposure control according to a predetermined program.

SDR is a drive circuit for the focus detection line sensor device SNS, and is selected when the signal C3DR is “H”.
It is controlled by microcomputer PR3 using So, SI, and 5CLK.

Signal φ given from drive circuit SDR to sensor device SNS
5ELO, φ5ELI are signals 5E from microcomputer PR3
LO, 5ELL itself is φ5ELO = “L”, φ5
When ELL-“L”, sensor row pair 5NS-1 (SNS
-1a, 5NS-1b), φ5ELO=“H”, φ5
When EL1="L", sensor row pair 5M5-4 (SN
S4a, 5NS-4b), φ5ELO-“L” φ5E
When L1="H", sensor row pair 5NS2 (SNS-
2a, 5NS-2b), φ5ELO="H", φ5E
When L1="H", sensor row pair S N S -3 (S
These are signals for selecting NS-3a and SNS-31), respectively.

After the accumulation is completed, set 5ELO and 5ELI appropriately,
Then, by sending clocks φSH and φHR3,
The image signals of the pair of sensor rows selected by 5ELO, 5ELL (φ5ELO9φSEL 1) are serially output from the output VOUT.

VPI, VF6. VF6. VP411 each sensor row pair 5NS-1 (SNS-1a, 5NS-1b),
5NS-2 (SNS-2a, 5NS2b), 5
NS-3 (SNS-3a, SNS-3b), 5
The monitor signal from the subject brightness monitor sensor placed near the NS-4 (SNS-4a, 5NS4b).
The voltage increases with the start of accumulation, thereby controlling the accumulation of each sensor array.

Signals φRES and φVR8 are sensor reset clocks, φHR8 and φSH are image signal readout clocks, φTl, φT2. φT3. φT4 is a clock for ending the accumulation of each pair of sensor columns.

The output VIDEO of the sensor drive circuit SDR is an image signal obtained by taking the difference between the image signal VOUT from the sensor device SNS and the dark current output, and then amplifying the difference with a gain determined by the brightness of the subject. The above-mentioned dark current output is the output value of the light-shielded pixels in the sensor array, and the SDR holds the output in a capacitor using the signal DSH from the microcomputer PRS, and performs differential amplification between this and the image signal. conduct. The output V I DEO is input to the analog input terminal of the microcomputer PR8, and the microcomputer PR8 inputs the same signal to A, /
After D conversion, the digital values are sequentially stored in predetermined addresses on the RAM.

Signal/TINTE1. /TINTE2. /TINTE3
．． /TINTE4 is the sensor row pair 5NS-1 (
SNS-1a, 5NS-1b).

5NS-2 (SNS-2a, 5NS-2b).

5NS-3 (SNS-3a, 5NS-3b).

This is a signal indicating that the charge accumulated in the 5NS-4 (SMS-4a, 5NS-4b) is appropriate and the accumulation has been completed. Upon receiving this signal, the microcomputer PR5 executes reading of the image signal.

The signal BTIME is a signal that gives the timing for determining the readout gain of the image signal amplification amplifier in the sensor drive circuit SDR, and the above circuit SDR normally responds from the voltage of the monitor signals VPO to VP3 at the time this signal becomes "H". Determine the readout gain of the pair of sensor columns.

CKI and CK2 are the above clock φRES.

This is a reference clock given from the microcomputer PR3 to the sensor drive circuit SDR in order to generate φVR8, φHR3, and φSH.

The microcomputer PR3 sets the communication selection signal C3DR to "H" and sends a predetermined "accumulation start command" to the sensor drive circuit SDR.
The storage operation of the sensor device W S N S is started by sending the signal to the sensor device W S N S .

As a result, photoelectric conversion of the subject image formed on each sensor is performed by the four sensor row pairs, and charges are accumulated in the photoelectric conversion element portion of the sensor.

At the same time, sensor signal VPI for brightness monitoring of each sensor
~VP4 increases and when this voltage reaches a predetermined level, the sensor drive circuit SDR outputs the signal /TINTE.
I~/TINTE4 each becomes "L" independently.

In response to this, the microcomputer PR3 outputs a predetermined waveform to the clock CK2. The sensor drive circuit SDR uses a clock φSH based on CK2.

φHR8 is generated and given to the sensor device SNS, and the sensor device SNS outputs image No. 1 according to the clock, and the microcomputer PRS uses its internal A/D conversion function to convert the signal to the analog input terminal in synchronization with the CK2 that it outputs. After A/D converting the output V I DEO input to the , it is sequentially stored in a predetermined address of RAM as a digital signal.

Note that the operations of the sensor drive circuit SDR and the sensor device SNS are disclosed in Japanese Patent Application Laid-Open No. 63-216905 as a focus detection device having two pairs of sensor arrays, so a detailed explanation will be omitted here. .

As described above, the microcomputer PR8 receives the image information of the subject image formed on each pair of sensor rows, and then performs a predetermined focus detection device to determine the amount of defocus of the photographic lens.

Next, the automatic focus adjustment device for a camera having the above configuration will be explained according to the flowchart below.

FIG. 5(a) is a very rough flowchart of the entire sequence of the camera.

When power supply starts to the circuit shown in Fig. 2, the microcomputer P
The RS starts execution from step (000) in FIG. 5(a). In step (001), the state of the switch SWI, which is turned on by pressing the release button in the first stage, is detected, and if it is off, the process moves to step (002), where all flags and variables are initialized. If the switch SWI is on, the process moves to step (OO3) and the camera starts operating.

In step (OO3), a ``rAE control'' subroutine for photometry, state detection of various switches, display, etc. is executed. A
Since the E control is not directly related to the present invention, a detailed explanation will be omitted. When the "subroutine rAE control" is completed, the process then moves to step (OO4).

In step (004), the rAF control subroutine is executed. Here, sensor storage, focus detection calculations, and lens drive automatic focus adjustment operations are performed.

When the "subroutine rAF control" is completed, Stella 7'
Return to (001) and step (00
3) and (004) are repeatedly executed.

Although the flowchart of this embodiment does not describe the release operation, it is purposely omitted because the release operation is not directly related to the present invention.

FIG. 5(b) is a flowchart of the "subroutine rAF control" executed in step (OO4).

When the subroutine rAF control J is called, the AF sub-control from step (011) is executed after step (010).

First, in step (011), a subroutine "accumulation" is executed. This subroutine performs sensor storage, image signal readout, calculations, etc.

A detailed explanation will be given later.

Next, in step (012), the subroutine “
Detect focus state. This subroutine calculates the defocus amount of the photographing lens from the focus state calculated in step (011).

Next, in step (013), a subroutine "focus determination" is executed. This subroutine determines whether or not the object is in focus based on the amount of defocus of the photographing lens calculated in step (012).

In the next step (014), if the focus state of the first lens is in focus, the process moves to step 016 and the lens is not driven. If it is not in focus, move to step (015),
Execute the subroutine "lens drive". This subroutine drives the lens to the in-focus position based on the amount of defocus of the photographic lens.

Next, the process moves to step (016), and the subroutine “A
Execution of "FIIJ control" ends.

The above is a rough outline of the AF sub-control. Hereinafter, the subroutine "accumulation" executed in step (011) related to the present invention will be explained in detail.

FIG. 5(C) is a flowchart of the subroutine "accumulation". When the subroutine "accumulation" is executed, the process goes to step (020), and the accumulation control from step (021) onwards is executed (.

First, in step (021), flags and memory necessary for distance measurement calculation are initialized.

Next, in step (022), pixel output data (hereinafter referred to as data correction data) in a state where each image sensor is not exposed to light during the maximum accumulation time is obtained.

) is stored at the address where the image signal of each sensor is to be stored. This data correction data is adjustment data required when the camera is assembled in the process, and this data is prepared for each image sensor for the number of pixels of each sensor.

Next, in step (023), the temperature detection circuit TEM
Input the current temperature T of the camera detected at P.

Next, in step (024), an appropriate coefficient is detected from the current temperature. Specifically, the temperature is below 20℃, from 20℃ to 30℃, from 30℃ to 40℃, and above 40℃.
It is divided into ROM or RA for each range.
Coefficients are prepared in advance in a memory such as M. An appropriate coefficient is read from the memory depending on which of the four areas the current temperature falls into.

In the next step (025), operations such as starting an interrupt timer for checking completion of accumulation and initializing a counter for measuring accumulation time are performed.

In the next step (026), an accumulation operation is started by sending an "accumulation start command" to the drive circuit SDR. Next, in step (027), it is determined whether calculations have been completed for all of the selected distance measurement points, and if calculations have been completed for all of the selected distance measurement points, step (032) is performed.
After the process moves to step (033) and performs processing to end the accumulation, such as interrupt prohibition processing, the execution of the subroutine ``accumulation'' ends. It is assumed that the distance measurement point is selected arbitrarily.

If it is determined in step (027) that the calculation has not been completed for all the selected distance measuring points, step (027)
Move on to 8). In this step, it is determined whether image signal input has been completed for the distance measuring points for which accumulation has been completed, and if there are any points for which accumulation has been completed but image signal input has not been completed, the process proceeds to step (030). Then, the subroutine "Image signal input J" is executed, and the process returns to step (027). A detailed explanation of the subroutine "Image signal input" will be given later.

In step (028), if all image signals have been input for the ones that have been stored, step (029) is performed.
Move to. In step (029), it is determined whether or not calculations have been completed for all distance measuring points for which image signals have been input, and if there are any that have not yet been calculated,
The process moves to step (031) and the subroutine "calculation" is executed. After execution of step (031), step (027)
) Return to

If all calculations have been completed in step (029), the process directly returns to step (027).

The above operations are constantly repeated during accumulation, and arithmetic processing is executed for each distance measurement point. Note that whether or not the accumulation has been completed is checked by interrupts that occur once every certain period of time (500 .mu.s) in the loop from steps (027) to (031). The interrupt process ``accumulation completion'' check for checking the completion of accumulation will now be explained.

FIG. 5(g) is a flowchart of the interrupt process ``accumulation completion check'' that occurs at regular intervals.

When an interrupt occurs, the process goes through step (040), and the accumulation completion check control from step (041) onward is executed.

First, in step (041), the timer for generating the next interrupt is updated. An interrupt will occur again 500 μs after this point.

In the next step (042), the accumulation time is measured.

The accumulation time is measured by counting the number of interruptions (the number of 500 μs).

Next, in step (043), it is determined whether the current accumulation time is the maximum accumulation time or not. If it is the maximum accumulation time, the process moves to step 048, and processing for forced accumulation termination is performed. Actually T I NTE 1゜TINTE2. TIN
TE3. , TINTE4 are all set to "L".

Thereafter, in step (049), the accumulation time of the distance measurement point for which the forced accumulation has been completed is stored.

In step (050), storage termination processing such as disabling the interrupt timer is performed. Thereafter, the process moves to step (051).

In step (043), if the accumulation time has not reached the maximum accumulation time, proceed to step (044),
It is determined whether or not there is a distance measurement point for which accumulation has just been completed, and if there is no distance measurement point for which accumulation has now been completed, the process moves to step (051).

If there is a station that has been accumulated, step (04)
In step 5), the accumulation time for that distance measurement point is stored.

In the next step (046), it is determined whether or not accumulation has been completed for all of the selected ranging points, and if not, the process moves to step (051). If all have been accumulated, step (04)
The process moves to step 7), where storage termination processing such as disabling the interrupt timer is performed, and the process moves to step 051, where the interrupt processing ends.

The above process is repeated once every 500 μS, and the completion of accumulation for each distance measurement point is detected and the accumulation time at that time is stored.

Returning to FIG. 5(C), the explanation will be continued.

The subroutine "image signal input" executed in step (030) will be explained.

FIG. 5(d) is a flow chart of the subroutine "Image signal input". When the subroutine "input image signal" is called, the process goes through step (060) and then step (0
61) Execute the input of subsequent image signals.

First, in step (061), parameters necessary for the image signal correction calculation described later, such as pixels in a state where no light hits the sensor at the shortest accumulation time for the sensor at the distance measurement point where the image signal input processing is performed. Store the output data (hereinafter referred to as short dark correction value) in memory. This short dark correction value is adjustment data when the camera is assembled in the process, and the minimum value of the pixel output of each of the A image and B image is adopted. Image A is the image accumulated on one of the pair of sensors, and image B
The image is the image stored on the other sensor.

In the next step (062), a "read command" is sent to the drive circuit SDR in order to input an image signal.

In the next step (063), operations such as setting the memory address for storing image signal data and setting the number of pixels are performed.

In the next step (064), the image signal of the A image is input.

FIGS. 5(e) and 5(f) are flowcharts of the subroutine "input of A image signal" executed in step 064.

Subroutine ``When the big basket of A image signals is called, it goes through step (070) and then the A image signal from step (071) onwards.
Controls image signal input.

First, in step (071), a predetermined pulse is output to the clock CK2, and the image output of the sensor is serially sent from the sensor drive circuit SDR to the analog input terminal of the A/D converter built in the microcomputer PR3 for each pixel. to input.

In the next step (072), the dark correction data DK(i) of the pixel that is about to be input in the sensor of the distance measurement point where the subroutine processing is being performed is loaded into the register.

In the next step (073), dark correction data DK (
Multiply i) by the temperature coefficient determined from the temperature detected before the start of accumulation.

Now, how to determine the actual temperature coefficient will be explained.

FIG. 1 is an example showing how the pixel output in a state where the sensor is not exposed to light changes with respect to temperature when this embodiment is incorporated into a camera. As you can see from this figure, when the temperature is below 20 degrees Celsius, no particularly large changes are observed, but when it exceeds around 20 degrees Celsius, the pixel output suddenly increases as the temperature changes. Recognize.

Dark correction data for setting the dark correction of a sensor with such temperature characteristics in step (072) (This data is adjusted during the process, so it is a value at room temperature, that is, around 25°C.) If you try to apply correction at low temperatures, the pixel output at low temperatures is smaller than the pixel output at room temperature, so there is a tendency for too much correction. Since it is larger than the output, the correction tends to be insufficient.

In order to solve this kind of problem, we first set the temperature area to 2.
Below 0℃, from 20℃ to 30℃, from 30℃ to 40℃
Divide into 4 parts A, B, and 40°C or higher.
Let them be C and D. The temperature area at room temperature is B.

Next, give a coefficient to each area. The way to find the coefficient is
First, the coefficient of temperature area B at room temperature is set to 1.

Next, to find the coefficient of A, calculate the ratio of the pixel output at the center temperature of area A of 0° C. to the pixel output at room temperature of 25° C., and use this value as the coefficient of area A.

The coefficients for areas C and D are calculated in the same way; the ratio between the pixel output at the center temperature of each area and the pixel output at room temperature 25° C. is calculated, and this value is used as the coefficient for each area. These coefficients are actually measured and input into the memory in advance at a factory or the like, and are read out from the memory in accordance with the detected temperature. By multiplying this read coefficient by the dark correction data set in step (072), a pixel output suitable for each temperature area is calculated.

By using the pixel output calculated here as dark correction data and later subtracting this value from the image signal, it is possible to cancel the pixel output when the sensor is not exposed to light. This makes it possible to handle changes in pixel output due to temperature when the sensor is not exposed to light.

In the next step (074), correction data of pixel output at the shortest accumulation time (short dark correction data DK) is required to calculate the correction amount according to the accumulation time.
5HORT) into the register. DKSHORT
may be a value common to one sensor, or may be a value for each pixel determined for each pixel, as described above.

In the next step (075), the difference between the pixel output when the sensor is not exposed to light during the maximum accumulation time and the pixel output when the sensor is not exposed to light during the shortest accumulation time is calculated, and this is calculated using DARK( i).

DARK (i) = DK (i) - DK 5HORT
In the next step (076), it is calculated how much value should be added or subtracted from the pixel output when the sensor is not exposed to light at the maximum accumulation time in order to obtain a correction value at an arbitrary accumulation time.

Assuming that the value to be added or subtracted is ADJ (i), it is calculated using the following formula.

ADJ(i) = Shortest accumulation time means that the interrupt timer for accumulation completion check is 500μs, so the shortest accumulation time is also 500μs.
apply.

In the next step (077), the correction amount DARK(i) at an arbitrary accumulation time is calculated.

DARK (i) = DK (i) + ADJ (i) By applying these corrections, even if the pixel output level when the sensor is not exposed to light fluctuates due to temperature or accumulation time, This makes it possible to prevent a decrease in distance measurement accuracy and low brightness limit.

In the next step (078), the image output of the sensor is
Convert and import. Let this value be Image (i).

In the next step (079), the image output of the sensor is A/
The previously calculated correction value is subtracted from the D-converted raw value to cancel the component of the pixel output when the sensor is not exposed to light.

Image (i) = Image (i) - DARK
(i) In the next step (080), if the above calculation result is positive, the process moves to step 082, and if it is a negative number, the above calculation result is set to O.

Image (i)=0 In the next step (082), a certain coefficient α is applied in order to correct optical light falloff, etc.

This certain coefficient α is adjustment data when the camera is assembled in the process, and is adjusted so that when uniform brightness is incident from the photographing lens, the image output of the sensor will also be at a - A certain coefficient is assigned to each pixel so as to match the maximum value of the output.

In step (083), the data obtained in the above (082) is input into the memory, and in step (084), it is detected whether or not the set pixel needle processing has been performed, and if it has been completed, the process returns. , if not completed, step (0
Returning to step 71), the above processing is executed for the next input pixel output.

The above operations are executed for each pixel of the A image sensor,
A temperature compensated A image signal is obtained. After completing the processing for image A in this way, step (065) in FIG. 5(d)
Steps (065) (06) where subsequent steps are executed
6) Processing, Step (063) The same processing as that for the A image described in (064) is performed on the B image, so the explanation thereof will be omitted.

As described above, temperature compensation is performed on the image signal of each sensor in the image signal input subroutine shown in FIG. The adjustment operation is performed accurately and a proper focus adjustment operation is always performed.

〔effect〕

As described above, in the present invention, since the image sensor output is corrected using the ambient temperature and accumulation time as parameters, it is possible to prevent the sensor output from changing depending on the temperature or accumulation time, and to always obtain an accurate image signal. This is something that can be obtained.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the temperature characteristics of an image sensor, Fig. 2 is a circuit diagram showing an embodiment of a camera having a processing device according to the present invention, and Fig. 3 is a focus detection diagram used in the camera in Fig. 2. FIG. 4 is a configuration diagram showing how the optical system shown in FIG. 3 is installed in the camera; FIG. FIG. PRS...Computer SNS...Sensor device TEMP...Temperature detection circuit 20 0 40 jiC) □Wenjun

Claims (2)

[Claims] (1) Correct the output of each pixel in the light accumulation type sensor when the accumulation operation is performed for a predetermined accumulation time in a non-light emitting state using the actual accumulation time when the above sensor is accumulated in a light emitting state. and adjusting means for adjusting each pixel output of the sensor obtained during the actual accumulation time using the correction value to obtain the corrected each pixel output. image sensor processing device. (2) It has a correction means that detects temperature and outputs a correction value according to the detected temperature, and an adjustment means that adjusts the output of each pixel in the photoaccumulation sensor using the correction value from the correction means. An image sensor processing device featuring: