JPH06331885A - Automatic focus detecting device - Google Patents

Abstract

(57) [Abstract] [Purpose] Optimum focus detection by eliminating the dispersion of the output of each focus detection sensor in the case of having multiple focus detection sensors and sharing the accumulation control signal for controlling them. It is possible to do. A storage control signal input means PRS for inputting a storage control signal shared by a plurality of focus detection sensors SNS, and a storage means RAM storing a correction coefficient for each pixel of each focus detection sensor. , A calculation for performing a calculation with the correction coefficient stored in the storage means for each pixel on the outputs of the plurality of focus detection sensors to uniformize the outputs of all the focus detection sensors for the uniform and uniform luminance surface. By providing the means PRS and performing a calculation with a predetermined correction coefficient for each sensor pixel for each focus detection sensor even if the number of inputs of the storage control signal is smaller than the number of focus detection sensors. , All the outputs of the focus detection sensors for the uniform brightness surface are made uniform.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a plurality of focus detecting sensors corresponding to a plurality of subject areas in a photographing screen, and a defocus amount of each area based on signals from the plurality of focus detecting sensors. The present invention relates to an improvement of an automatic focus detection device including a defocus amount detection unit that repeatedly detects.

[0002]

2. Description of the Related Art Conventionally, most of the automatic focus adjustment systems for single-lens reflex cameras have a "focus detection (sensor signal input, focus detection calculation), lens drive" for one area such as the center of the photographing screen. It was intended to focus on the subject by repeating the cycle.

In recent years, a plurality of focus detection areas have been provided in the photographing screen, and the detection areas can be automatically selected according to various subjects and situations, or the photographer can select an arbitrary area within the plurality of areas. By doing so, many devices have been proposed that are capable of adjusting the focus on areas other than the conventional central portion of the screen.

When a device of this type is provided with a plurality of focus detection areas, a plurality of photoelectric conversion element arrays, so-called sensor arrays corresponding to the respective areas are naturally required. Usually, these sensor rows are formed as the same semiconductor element, but they are not always provided with the same characteristics, and a remarkable example in this case is uneven sensitivity.

[0005]

It is most desirable to independently input the storage control signal to each sensor for the sensitivity unevenness of a plurality of sensor arrays, but the circuit scale becomes large.
It greatly affects yield and cost. In addition, the number of input terminals as a semiconductor element increases, which is a disadvantageous factor in terms of mounting area.

Therefore, in many cases, since the storage control signal is commonly used, it is the current situation that only one sensor array outputs the optimally controlled signal.

(Object of the Invention) An object of the present invention is to have a plurality of focus detection sensors and share an accumulation control signal for controlling the same, thereby eliminating variations in the outputs of the focus detection sensors. An object of the present invention is to provide an automatic focus detection device capable of performing optimum focus detection.

[0008]

According to the present invention, there is provided storage control signal input means for inputting a storage control signal shared by a plurality of focus detection sensors, and each of the focus detection sensors for each pixel. With respect to the outputs of the storage unit that stores the correction coefficient and the plurality of focus detection sensors, the correction coefficient stored in the storage unit is calculated for each pixel, and all the focus detections for the uniform and uniform luminance surface are performed. And a calculation means for equalizing the sensor output, and even if the number of inputs of the storage control signal is smaller than the number of focus detection sensors, a predetermined correction coefficient is provided for each sensor pixel for each focus detection sensor. By performing the calculation with, all the focus detection sensor outputs for the uniform and uniform luminance surface are made uniform.

Further, according to the present invention, a storage control signal output means for outputting a storage control signal commonly to a plurality of focus detection sensors, and the storage operation when an arbitrary region is selected by the selection means. The storage control signal from the control signal output means is provided with a conversion means for converting the signal into an optimum signal for the focus detection sensor corresponding to the selected area, and when an arbitrary area is selected by the selection means, The accumulation control signal from the accumulation control signal output means is converted into a signal that is optimum for the focus detection sensor corresponding to the selected area.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the illustrated embodiments.

FIG. 1 is a diagram showing a perspective view of a focus adjusting optical system of a single-lens reflex camera equipped with an automatic focus adjusting device according to a first embodiment of the present invention.

In FIG. 1, MSK is a visual field mask, which has a cross-shaped opening MSK-1 in the center and vertically long openings MSK-2 and MSK-3 in the peripheral portions on both sides. F
LDL is a field lens and corresponds to the three openings MSK-1, MSK-2, MSK-3 of the visual field mask, and three parts FLDL-1, FLDL-2, FLDL.
-3. DP is a diaphragm, and there are a total of four openings DP-1a and DP-1 in the center, one pair vertically and horizontally.
b, DP-4c, DP-4d, and a pair of openings DP-2a, DP-2b and DP-3 on the left and right peripheral portions.
a and DP-3b are provided respectively. Regions FLDL-1, FLDL- of the field lens FLDL
2, FLDL-3 are these aperture pairs DP-1,
It has a function of forming an image of DP-2 and DP-3 in the vicinity of the exit pupil of an objective lens (not shown). AFL consists of 4 pairs of 8 lenses AFL-1a, AFL-1b, AFL-4a, AF
L-4b, AFL-2a, AFL-2b, AFL-3
It is a secondary imaging lens composed of a and AFL-3b, and is arranged behind the aperture DP corresponding to each aperture.
The SNS has four pairs of sensor lines SNS-1a and SNS- in total.
1b, SNS-4a, SNS-4b, SNS-2a, S
The line sensor is composed of NS-2b, SNS-3a, and SNS-3b, and is arranged so as to receive the image corresponding to each secondary imaging lens AFL.

In the focus adjusting optical system shown in FIG. 1, when the focus of the taking lens is in front of the film surface, the subject images formed on each pair of sensor rows are close to each other, and the focus is in the rear. In some cases, the subject images will be separated from each other. Since the relative position displacement amount of the subject image has a specific functional relationship with the defocus amount of the photographing lens, if an appropriate calculation is performed for each sensor output in each sensor row pair, the defocus amount of the photographing lens, A so-called defocus amount can be detected.

By adopting the configuration described above, for an object in which the light amount distribution changes only in one direction, up and down or left and right, in the vicinity of the center of the range photographed or observed by the objective lens (not shown). It is also possible to measure the distance, and the opening MSK- around the field mask other than the center
2. Distance can be measured even for an object located at a position corresponding to MSK-3.

FIG. 2 is an optical system layout diagram of a single-lens reflex camera having the focus adjusting optical system shown in FIG.

In the figure, LNS is a zoom photographing lens, QRM
Is a quick return mirror, FSCRN is a focusing screen, PP is a pentaprism, EPL is an eyepiece, FPLN is a film surface, SM is a sub-mirror, MSK is a field mask, and IC.
F is an infrared cut filter, FLDL is a field lens, RM1 and RM2 are first and second reflection mirrors, and SHMS.
K is a light-shielding mask, DP is a diaphragm, AFL is a secondary imaging lens, AFP is a prism member having a reflecting surface AFP-1 and an exit surface AFP-2, and SNS is the above-mentioned line having a cover glass SNSCG and a light receiving surface SNSPLN. It is a sensor.

The prism member AFP has a reflection surface AFP-1 on which a metal reflection film such as aluminum is vapor-deposited, reflects the light flux from the secondary imaging lens AFL, and exits the surface AFP-2.
It has the effect of polarization.

FIG. 3 is a block diagram showing an example of a concrete structure of a camera provided with the automatic focus adjusting device as shown in FIGS.

In FIG. 3, PRS is a control circuit of the camera, for example, a CPU (central processing unit), ROM, R
It is a one-chip microcomputer having AM and A / D conversion functions. The control circuit PRS performs a series of camera operations such as an automatic exposure control function, an automatic focus adjustment function, and film winding / rewinding in accordance with the camera sequence program stored in the ROM. Therefore, the control circuit PRS is provided with communication signals SO, SI, SCL.
K and the communication selection signals CLCM, CSSDR, and CDRD are used to communicate with the peripheral circuits in the camera body and the control device in the lens to control the operation of each circuit and the lens.

SO is a data signal output from the control circuit PRS, SI is a data signal input to the control circuit PRS, and SCLK is a synchronous clock of the signals SO and SI.

LCM is a lens communication buffer circuit,
When the camera is operating, power is supplied to the lens power supply terminal VL, and the selection signal C from the control circuit PRS is supplied.
When the LCM is at a high potential level (hereinafter abbreviated as "H" and a low potential level is abbreviated as "L"), it serves as a communication buffer between the camera and the lens.

When the control circuit PRS sets the communication selection signal CLCM to "H" and sends out predetermined data as the signal SO in synchronization with the synchronization clock SCLK, the lens communication circuit LC
M is SCLK, S via the camera / lens communication contact
The respective buffer signals LCK and DCL of O are output to the lens. At the same time, the buffer signal of the signal DLC from the lens is output to SI, and the control circuit PRS inputs the lens data from SI in synchronization with SCLK.

DDR is a circuit for detecting and displaying various switches SWS, is selected when the signal CDRD is "H", and is controlled by the control circuit PRS using SO, SI and SCLK. That is, the display of the display circuit DSP2 of the camera is switched based on the data sent from the control circuit PRS, and the on / off state of various operation members of the camera is notified to the control circuit PRS by communication.

SW1 and SW2 are switches interlocked with a release button (not shown). The switch SW1 is turned on when the release button is pressed in the first step, and the switch SW2 is turned on when the release button is pressed in the second step. The control circuit PRS performs photometry and automatic focus adjustment when the switch SW1 is turned on, and exposure control and subsequent film winding are triggered by turning on the switch SW2.

The switch SW2 is connected to the "interruption input terminal" of the control circuit PRS, which is a microcomputer, so that even if the program is executed when the switch SW1 is on, an interrupt is generated by turning on the switch SW2.
The configuration is such that control can be immediately transferred to a predetermined interrupt program.

MTR1 is a film feeding motor, MTR2 is a motor for mirror up / down and shutter spring charging, and forward / reverse control is performed by respective drive circuits MDR1 and MDR2. The signal M1 input from the control circuit PRS to the drive circuits MDR1 and MDR2
F, M1R, M2F and M2R are signals for motor control.

MG1 and MG2 are shutter front curtain and rear curtain running start magnets, which are energized by signals SMG1 and SMN2 and amplification transistors TR1 and TR2, respectively, and control circuit P.
Shutter control is performed by RS.

The motor drive circuits MDR1 and MDR2
Since the control of 1 and the shutter control are not directly related to the present invention, detailed description thereof will be omitted.

The signal DCL input to the in-lens control circuit LPRS in synchronism with LCK is command data from the camera to the lens unit LNS2, and the operation of the lens in response to the command is predetermined. The in-lens control circuit LPRS2 analyzes the command according to a predetermined procedure,
Focus adjustment and aperture control operations, operation status of each part of the lens from output DLC (focus adjustment optical system drive status, diaphragm drive status, etc.) and various parameters (open F number, focal length, defocus amount vs. focus adjustment) The coefficient of the movement amount of the optical system, etc.) is output.

This embodiment shows an example of a zoom lens. When a focus adjustment command is sent from the camera, the focus adjustment motor LTMR is driven by the signal LMF according to the driving amount and direction sent at the same time. Driven by the LMR, the optical system is moved in the optical axis direction to perform focus adjustment. The amount of movement of the optical system is detected by the photocoupler by detecting the pattern of the pulse plate that rotates in conjunction with the optical system, and is monitored by the pulse signal SENCF of the encoder circuit ENCF that outputs a number of pulses according to the amount of movement, The coefficient is calculated by the counter in the internal control circuit LPRS, and when the predetermined movement is completed, the internal lens control circuit LPRS itself sets the signals LMF and LMR to "L" to control the motor LMTR.

Therefore, once the focus adjustment command is sent from the camera, the control circuit PRS of the camera does not have to be involved in the lens driving at all until the lens driving is completed. Also, the contents of the counter can be sent to the camera when requested by the camera.

When an aperture control command is sent from the camera, a stepping motor DMTR known for aperture drive is driven in accordance with the number of aperture steps sent at the same time. Since the stepping motor DMTR can be open-controlled, it does not need an encoder for monitoring the operation.

ENCZ is an encoder circuit attached to the zoom optical system, and the in-lens control circuit LPRS inputs the signal SENCZ from the encoder circuit ENCZ to detect the zoom position. Lens parameters at each zoom position are stored in the in-lens control circuit LPRS, and when there is a request from the control circuit PRS on the camera side, the parameter corresponding to the current zoom position is sent to the camera.

SPC is an exposure control sensor for receiving light from a subject through the taking lens, and its output SS
PC is input to the analog input terminal of the control circuit PRS,
It is used for automatic exposure control according to a predetermined program after A / D conversion.

SDR is a sensor drive circuit of a line sensor SNS for focus detection which is composed of a CCD or the like, and is selected when the signal CSDR is "H", SO, SI, SC.
It is controlled from the control circuit PRS using LK.

From the sensor drive circuit SDR to the line sensor S
Signals .phi.SEL0 and .phi.SEL1 given to NS are control circuit P.
With signals SEL0 and SEL1 from RS, φSE
Sensor array SN when L0 = “L” and φSEL1 = “L”
S-1 (SNS-1a, SNS-1b) to φSEL0
= “H” φSEL1 = “L”, sensor array SNS-4
(SNS-4a, SNS-4b), φSEL0 =
When "L" and φSEL1 = "H", the sensor array SNS-2
(SNS-2a, SNS-2b), φSEL0 =
When “H” and φSEL1 = “H”, the sensor array SNS-3
This is a signal for selecting each of (SNS-3a, SNS-3b).

After the accumulation is completed, the signals SLE0 and SEL1 are appropriately set, and then the clocks φSH and φHRS are sent, whereby the signals SEL0 and SEL1 (φSEL
0, φSEL1) output the image signal of the sensor array selected
It is output serially from VOUT.

VP1, VP2, VP3 and VP4 are sensor arrays SNS-1 (SNS-1a, SNS-1), respectively.
b), SNS-2 (SNS-2a, SNS-2b), S
NS-3 (SNS-3a, SNS-3b), SNS-4
A monitor signal from a subject brightness monitor sensor arranged in the vicinity of (SNS-4a, SNS-4b) causes the voltage to increase with the start of accumulation, whereby the accumulation control of each sensor array is performed.

Signals φRES and φVRS are sensor reset clocks, φHRS and φSH are image signal read clocks, and φT1, φT2, φT3, and φT4 are clocks for ending the accumulation of each sensor column pair.

The output VIDEO of the sensor drive circuit SDR is an image signal amplified by a gain determined by the brightness of the subject after taking the difference between the image signal VOUT from the line sensor SNS and the dark current output. The dark current output is an output value of a light-shielded pixel in the sensor array, and the sensor drive circuit S
The DR holds its output in a capacitor by the signal DSH from the control circuit PRS, and differentially amplifies the output with this. The output VIDEO is input to the analog input terminal of the control circuit PRS, and the control circuit PRS, after A / D converting the signal, sequentially stores the digital value at a predetermined address on the RAM.

Signals / TINTE 1, / TINTE 2, / TINTE
3 and / TINTE 4 are sensor arrays SNS-1 (SN
S-1a, SNS-1b), SNS-2 (SNS-2)
a, SNS-2b), SNS-3 (SNS-3a, SN
S-3b), SNS-4 (SNS-4a, SNS-4)
The control circuit PRS receives the signal indicating that the electric charge accumulated in b) is proper and the accumulation is completed, and executes the reading of the image signal.

The signal BTIME is a signal that gives a timing for determining the read gain of the image signal amplification amplifier in the sensor drive circuit SDR. Normally, the sensor drive circuit SDR normally outputs the monitor signals VP1 to VP1 at the time when this signal becomes "H". The read gain of the corresponding sensor array is determined from the voltage of VP4.
Specifically, based on the vertical relation between the comparison level generated based on the gain determination data sent in advance from the control circuit PRS using SCLK and SO, and the levels of the monitor signals VP1 to VP4 at the timing of the signal BTIME. It is determined. In this embodiment, this comparison level is common to the monitor signals VP1 to VP4.

CK1 and CK2 are the above clock φRES,
It is a reference clock given from the control circuit PRS to the sensor drive circuit SDR in order to generate φVRS, φHRS, and φSH.

The control circuit PRS sets the communication selection signal CSDR to "H" and sends a predetermined "accumulation start command" to the sensor drive circuit SDR, whereby the line sensor SN
The accumulation operation of S is started.

As a result, the subject image formed on each sensor is photoelectrically converted by the four sensor row pairs, and electric charges are accumulated in the photoelectric conversion element portion of the line sensor SNS. At the same time, the signals VP1 to VP of the brightness monitor sensor of each sensor
4 rises, and when this voltage reaches a predetermined level,
The sensor drive circuit SDR uses the signals / TINTE1 to / TINTE
4 becomes "L" independently.

In response to this, the control circuit PRS receives the clock C
A predetermined waveform is output to K2. The sensor drive circuit SDR uses clocks φSH and φHR based on the reference clock CK2.
S is generated and given to the line sensor SNS, the line sensor SNS outputs an image signal according to the clock, and the control circuit PRS synchronizes with CK2 output by itself and has an analog input terminal with an internal A / D conversion function. Output VIDEO input to is converted from analog to digital, and then converted to digital signal in RAM
Sequentially store the data in a predetermined address.

The operation of the sensor drive circuit SDR and the line sensor SNS is disclosed in Japanese Patent Application Laid-Open No. 63-216905 as a focus detection device having two pairs of sensor lines. Therefore, detailed description will be given here. Omit it.

As described above, the control circuit PRS can receive the image information of the subject image formed on each sensor array pair and then perform a predetermined focus detection calculation to know the defocus amount of the taking lens. I can.

Next, the operation of the camera having the above-described structure during automatic focus adjustment will be described with reference to the following flow chart.

FIG. 4 is a flowchart of the sequence of the entire camera, which is very rough.

When power supply to the circuit shown in FIG. 3 is started,
The control circuit PRS starts execution from step (000) in FIG. In step (001), the state of the switch SW1 that is turned on by pressing the release button in the first step is detected. If it is off, the process proceeds to step (002) to initialize all flags and variables. Then, it is detected in step (001) that the switch SW1 is turned on again.

On the other hand, in step (001) the switch SW
If 1 is ON, the process proceeds to step (003) to start the camera operation.

In step (003), an "AE control" subroutine for photometry, state detection of various switches and display is executed. When the sub-routine "AE control" is completed, the process proceeds to step (004).

In step (004), the "AF control" subroutine is executed. Here, sensor accumulation, focus detection calculation, and lens-driven automatic focus adjustment operation are performed. When the sub-routine "AF control" is completed, the process returns to step (001) again, and step (00
3) and (004) are repeatedly executed.

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

FIG. 5 is a flow chart of the "AF control" subroutine executed in the step (004).

When the "AF control" subroutine is called, the AF control from step (011) is executed through step (010).

First, in step (011), the "focus detection" subroutine is executed. Here, focus detection calculation is performed from the accumulation and reading of the image signal to each sensor for focus detection operation (details will be described later with reference to FIGS. 6 and 7).

In the next step (012), an "area selection" subroutine for selecting which area from the currently selected areas and using the defocus amount is executed.
In this embodiment, the selection area is normally the entire area, that is, automatic selection. The selection area can be specified by pressing the selection area setting switch in the various switches SWS of FIG.

At step (013), a "lens drive" subroutine is executed. Here, step (011)
In the defocus amount detected at step (01
The lens is driven based on the defocus amount of the area selected in 2) (details will be described later with reference to FIG. 10).

After the lens driving is completed, the "AF control" subroutine is returned from step (014).

6 and 7 are flowcharts of the subroutine "focus detection" executed in step (011).

When this subroutine is called, the focus detection operation from step (111) is executed through step (110).

First, in step (111), it is determined whether or not the power is turned on and the AF control is the first time. If it is the first time, the process proceeds to step (112) to initialize the selection sensor. Turn into.

Then, in step (113), the subroutine "accumulation start" is executed. This subroutine is a routine for starting the accumulation operation of the sensor. Specifically, the accumulation start command is sent to the sensor drive circuit SDR to start the accumulation operation of the line sensor SNS, and at the same time, the sensor drive circuit SDR outputs the accumulation operation. Sensor accumulation end signal / TINT
This is a subroutine that enables the interrupt function so that the control circuit PRS can execute the "accumulation completion interrupt" by E1 to / TINTE4. This allows four sensor arrays SNS
When the storage of -1 to SNS-4 is completed, each storage completion interrupt is executed.

Completion of accumulation of each sensor is signal / TINTE 1 //
It can be detected by the fall of TINTE 4, and these signals are connected to the “input terminal with interrupt function” of the control circuit PRS. In the diagram of FIG. 6, the interrupt control is indicated by the broken line, and the signals / TINTE 1 to
When an interrupt is generated by / TINTE 4, the control shifts to each interrupt routine shown in FIG. Therefore, for example, if the charge accumulation in the sensor array SNS-1 becomes appropriate and the signal / TINTE 1 from the sensor drive circuit SDR falls, in response to this, the process proceeds to the interrupt routine of step (150) and subsequent steps in FIG. 7. You can do it.

The interrupt routine after step (150) in FIG. 7 is a routine for inputting the image signal of the sensor array SNS-1.

In step (151), the sensor array SNS-
After inputting the image signal of 1, the interrupt routine is returned in step (152). The image signal is input to the control circuit P
Output VIDEO input to the analog input terminal of RS is serial A / D converted, and the digital data is converted into image signal data in a state in which optimum storage control is performed by performing the calculation described later, and then a predetermined RAM area It is achieved by sequentially storing in.

Sensor array SNS-2, SNS-3, SNS
When the accumulation of -4 is completed, the same interrupt control is performed.
Steps (153), (156) and (1
59), and the image signal of each sensor is input.

A specific method of the subroutine "accumulation start" and image signal input is disclosed in Japanese Patent Laid-Open No. 216905/1988, so a detailed description thereof will be omitted.

Returning to FIG. 6, the description will be continued.

Since the image signal input processing of each sensor is interrupt controlled, steps (114) to (126) in the figure are performed.
During the execution of the focus detection calculation, etc., the processing is preferentially processed whenever the accumulation is completed.

Now, when the accumulation operation of the sensor is started in step (113), the process proceeds to step (114).

In step (114), the sensor array SNS-
It is determined whether the focus detection calculation 1 has been completed, and if not completed, the process proceeds to step (115).

In step (115), the sensor array SNS
-1 determines whether the interrupt processing of the image signal input is already completed, and if completed, moves to step (116) to execute the focus detection calculation based on the image signal of the sensor array SNS-1. . Since a specific calculation method for detecting the defocus amount is disclosed in Japanese Patent Laid-Open No. 61-160824, detailed description thereof will be omitted.

In step (114), the sensor array SNS-1
If the focus detection calculation of the sensor array SNS-1 is not completed, or if the input of the image signal of the sensor array SNS-1 is not completed in step (115), or if the focus of the sensor array SNS-1 is selected in step (116). After the detection calculation is completed, step (1
Go to 17).

Steps (117), (118), (11)
In 9), the above-described processing is performed on the sensor array SNS-2.

Further steps (120), (121),
In (122), the sensor array SNS-3 is used, whereas in steps (123), (124) and (125), the sensor array SNS-3 is used.
The above-described processing is performed on each S-4.

In step (126), it is judged whether or not the focus detection calculation corresponding to all the sensors is completed,
If not completed, the process proceeds to step (114), and if all completed, the process proceeds to step (127).

To summarize the above, step (11
After the accumulation operation is started in 3), steps (114) to (126) are repeatedly executed while waiting for the image signals of the respective sensors to be read by interrupt processing, and the image signals are sequentially read from the read sensor. This means that focus detection calculation is being performed.

When the focus detection calculation of all the sensors is completed, the "focus detection" subroutine is returned in step (127).

Here, the above-mentioned image signal input subroutine [steps (151), (154), (157), (1)
58)] will be described.

The purpose of the image signal conversion performed here is to compare the signal BTIME, which is the input for accumulation control, with the comparison level (hereinafter, AGCLVL
It is to correct the output variation between the lines due to the common setting of all lines. The cause of the variation is the sensitivity difference of the sensor itself or the comparison level AGCL.
These include variations in inputting VL to the control circuit of each line (sensor array).

In this embodiment, the comparison level AGCLVL is adjusted with respect to the sensor row having the highest output for the uniform luminance surface.
Shall be set.

Here, it is assumed that an output having variations as shown in FIG. 8A is obtained for the uniform luminance plane. 8 and 9, the sensor array SNS-
1 to SNS-4 are shown by lines (LINE) 1 to 4.

The bending of each output is unevenness due to each optical system up to the sensor array, which is so-called shading unevenness. Conventionally, in the case of performing these corrections, FIG.
As shown in (b), the main purpose is to make each line uniform,
Here, the maximum value in each line (MAXn, n = 1 to 4)
It shows the case of matching. In the image signal conversion for this correction, a correction coefficient SHn (I) as shown in the following equation is obtained for each pixel on each line, and the read outputs (A / D conversion values) Imn (I) and SHn ( I) calculation result IMn
This is performed by storing (I) in a predetermined place on the RAM.

SHn (I) = {MAXn−Imn (I)} / Imn (1) IMn (I) = Imn (I) + Imn (I) × SHn (I) (2) However, FIG. As can be seen from (b), the variation between MAXn, which is the output difference between the lines, still remains.

In this embodiment, attention is paid to this fact, and the correction of the shading unevenness and the output unevenness between the lines are attempted to be eliminated all at once.

That is, the correction coefficient obtained in the above equation (1) is set not for the maximum value MAXn of each line but for the maximum value MAX of all lines, so that the above two irregularities are once corrected. Can be corrected to.

This state is shown in FIGS. 9 (a) and 9 (b). Further, the equations for the above equations (1) and (2) are the following equations (3) and (2).

SHn (I) = {MAX-Imn (I)} / Imn (3) IMn (I) = Imn (I) + Imn (I) × SHn (I) (2) The correction coefficient obtained by the equation (3) is stored in advance in the RAM which is a storage means in the control circuit PRS. Further, as is clear from the above equation (3), this correction coefficient also serves as a correction coefficient for uneven output of the focus detection sensor by the optical system of the defocus amount detection means.

FIG. 10 shows a flowchart of the "lens drive" subroutine.

When this subroutine is executed, in step (311), the lens unit LNS is communicated with and two data "S" and "PTH" are input.

Here, the defocus amount D for focus adjustment
A value obtained by converting the amount of movement of the focus adjustment optical system into the number of output pulses of the encoder by EF, S and PTH, so-called lens drive amount FP, is given by the following equation.

FP = DEF.S / PTH The step (312) executes the above equation as it is.

At the next step (313), the lens drive amount FP obtained at the step (312) is sent to the lens unit LNS2 to instruct the drive of the focus adjusting optical system.

At the next step (314), it is communicated with the lens to detect whether or not the driving of the lens driving amount FP instructed at step (313) is completed, and when the driving is completed, the process proceeds to step (315). Then, the "lens drive" subroutine is returned.

According to the first embodiment described above, even when the number of storage control signals input is smaller than the number of sensors for a plurality of sensor rows corresponding to a plurality of subject areas,
By performing a calculation with a predetermined coefficient for each sensor pixel for each sensor output, it is possible to realize a state equivalent to optimally controlling all sensor outputs.

The calculation here is a calculation for making the sensor outputs of all the focus detection areas uniform with respect to the uniform brightness surface. Further, the fact that the coefficient also serves as a correction coefficient for the output unevenness of the focus detection sensor by the optical system of the defocus amount detecting means is effective in reducing the storage area of the coefficient and the calculation time.

(Second Embodiment) FIG. 11 is a schematic diagram of an automatic focus detection device executed in the second embodiment of the present invention.
It is a flowchart of a "F control" subroutine. In addition,
The schematic structure of the apparatus, the layout in the camera, and the circuit diagram are exactly the same as in the first embodiment. Also, since the general sequence of the entire camera is the same, it is omitted here.

When the "AF control" subroutine is called, the AF control of step (411) and thereafter is executed through step (410).

First, in step (411), it is determined whether the focus detection area selection is the entire area, that is, automatic selection, or arbitrary, that is, a designated area. If not optional, perform steps (412) to (415) below for the first
The same procedure as in the embodiment of

If it is determined in step (411) that the selection is optional, the process proceeds to step (416). As described in the first embodiment, the selection area setting switch in the various switches SWS in FIG. 3 can be used to specify the selection area for the optional selection.

In step (416), the above-mentioned signal BTIM
Sensor SN in the area specified with comparison level AGCLVL at E
It is converted to be optimal for S-n. That is, the comparison level AGCLVL that is adjusted and set for the sensor array having the highest output on the uniform luminance surface is converted into a level that matches the specified area, assuming normal automatic selection.

A detailed description will be given with reference to FIG.

In this case, since line 3 shows the highest output, if the area of line 3 is designated,
No conversion needed. If the area of line 1 is specified, in this case, it is sufficient to accumulate more than the normal control level so that “MAX1 = MAX3”. Therefore, the comparison level AGCLVL may be raised by performing the following conversion on the comparison level AGCLVL.

AGCLVL = AGCLVL × (MAX3 / MAX1) (4) The above equation (4) is applied to another sensor array, that is, lines 2 to 4.
The same applies to. Generally, the conversion formula for the line n can be expressed as AGCLVLn = AGCLVL × (MAX / MAXn) (5) if the maximum value in all lines is MAX. In step (416), the conversion coefficient MAX / MAXn for each line is fetched from the area stored at the time of adjustment, and the conversion of equation (5) is performed.

In the following step (417), the "focus detection 2" subroutine is executed. Here, the focus detection calculation is performed from the accumulation and readout of the image signal of the designated sensor array for the focus detection operation (details will be described later with reference to FIG. 12).

At the next step (418), the comparison level is returned to the initial setting in preparation for the next focus detection operation.

When the focus detection calculation for the specified area is completed, the "lens drive" sub routine is executed in step (414) based on the result, as in the first embodiment, and this "AF control" subroutine is executed. The step (41
Return at 5).

FIG. 12 is a flowchart of the "focus detection 2" subroutine executed in the step (417).

When this "focus detection 2" subroutine is called, it goes through step (210) and then step (21
1) The subsequent focus detection operations are executed.

First, in step (211), it is determined whether or not the power is turned on and the first AF control is performed. If it is the first AF control, the selection sensor is initialized in step (212). .

Then, in step (213), "accumulation start"
Execute a subroutine. However, the sensor accumulation end signal from the sensor drive circuit SDR here is only the signal / TINTEn of the sensor row n for the designated and selected area, and the control circuit PRS executes the "accumulation completion interrupt" only by this signal / TINTEn. This is a subroutine that enables the interrupt function as described above.

Now, when the accumulation operation of the designated selection sensor is started in step (213), the process proceeds to step (214).

In this step (214), the sensor array SN
It is determined whether or not the S-n accumulation is completed, and if it is not completed, the process remains in step (214). If the accumulation of the sensor array SNS-n is completed in step (214), the process proceeds to step (215) to input the image signal of the sensor array SNS-n. Incidentally, the conversion of the image signal here is correct only by the conversion for correcting the shading unevenness in each line as in the conventional case.

Then, in step (216), the sensor S
When the focus detection calculation based on the image signal of NS-n is executed and the focus detection calculation of the designated selection area is completed, step (21
The "focus detection 2" subroutine is returned in 7).

In the second embodiment, when an arbitrary area is selected from a plurality of focus detection areas according to the intention of the photographer, the sensor corresponding to the area for which the sensor accumulation control signal is selected is selected. By converting the signal into the optimum signal, it becomes possible to optimally control the sensor output in the selected area.

By adopting the configurations of the above-described second and second embodiments, the storage control signal is independently provided for each sensor even for a plurality of sensor rows that do not necessarily have the same characteristics. It is possible to realize a focus detection device which is advantageous in terms of mounting area because the circuit scale can be made small without inputting to the device and the yield and cost as well as the number of input terminals can be reduced.

(Modification) In the first and second embodiments described above, the determination of the comparison level AGCLVL has been described so as to match the maximum output value of the uniform brightness plane, but this is the minimum output value. Matching is also effective. In this case, the conversion is performed in the direction of compressing the image signal, and the stability in terms of S / N and mass production is high.

[0121]

As described above, according to the present invention,
Storage control signal input means for inputting a storage control signal shared by a plurality of focus detection sensors, storage means for storing a correction coefficient for each pixel of each focus detection sensor, and a plurality of focus detections For the output of the sensor for each pixel, the calculation with the correction coefficient stored in the storage means,
Even if the number of inputs of the storage control signal is smaller than the number of focus detection sensors, the calculation means for equalizing all the focus detection sensor outputs with respect to the uniform and uniform luminance surface is provided. By performing calculation with a predetermined correction coefficient for each sensor pixel, all focus detection sensor outputs for the uniform and uniform luminance surface are made uniform.

Further, storage control signal output means for outputting a storage control signal commonly to a plurality of focus detection sensors,
When an arbitrary area is selected by the selection means, a conversion means for converting the accumulation control signal from the accumulation control signal output means into a signal optimum for the focus detection sensor corresponding to the selected area. When an arbitrary area is selected by the selection means, the accumulation control signal from the accumulation control signal output means is converted into a signal that is optimum for the focus detection sensor corresponding to the selected area. I have to.

Therefore, by having a plurality of focus detection sensors,
In the case of sharing the accumulation control signal for controlling this, it is possible to eliminate variations in the outputs of the focus detection sensors and perform optimum focus detection.

[Brief description of drawings]

FIG. 1 is a perspective view of a focus adjusting optical system of a single-lens reflex camera equipped with an automatic focus detection device according to a first embodiment of the present invention.

FIG. 2 is an optical system layout diagram of the single-lens reflex camera in FIG.

3 is a block diagram of a main part of the single-lens reflex camera of FIG. 1.

FIG. 4 is a flow chart showing a general operation of the single-lens reflex camera of FIG.

5 is a flowchart showing an operation of an "AF control" subroutine of FIG.

FIG. 6 is a flowchart showing a part of the operation of the “focus detection” subroutine of FIG.

FIG. 7 is a flowchart showing a continuation of the operation of FIG.

FIG. 8 is a diagram for explaining a conventional image signal conversion calculation.

FIG. 9 is a diagram for explaining an image signal conversion calculation in the first embodiment of the present invention.

10 is a flowchart showing an operation of a "lens drive" subroutine of FIG.

FIG. 11 “AF control” in the second embodiment of the present invention.
It is a flowchart which shows operation | movement of a subroutine.

12 is a flowchart showing an operation of a "focus detection 2" subroutine of FIG.

[Explanation of symbols]

 PRS control circuit SDR sensor drive circuit LPRS in-lens control circuit SNS line sensor SDR sensor drive circuit

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location 9119-2K G03B 3/00 A

Claims (6)

[Claims] 1. A plurality of focus detection sensors corresponding to a plurality of subject areas in a shooting screen, and a defocus amount for repeatedly detecting a defocus amount of each area based on signals from the plurality of focus detection sensors. In an automatic focus detection device including a detection unit and a lens drive unit that drives a focus adjustment optical system of a photographic lens based on the defocus amount from the defocus amount detection unit, an automatic focus detection device for the plurality of focus detection sensors Storage control signal input means for inputting a storage control signal commonly used by the plurality of focus detection sensors, storage means for storing a correction coefficient for each pixel of each focus detection sensor, and outputs of the plurality of focus detection sensors. , For each pixel, performing arithmetic operation with the correction coefficient stored in the storage means, and providing arithmetic means for equalizing all focus detection sensor outputs with respect to the uniform brightness surface. Characteristic automatic focus detection device. 2. The correction coefficient stored in the storage means also serves as a correction coefficient for correcting variations in the output of the focus detection sensor by the optical system of the defocus amount detection means. Automatic focus detection device. 3. The uniformization of all the focus detection sensor outputs with respect to the uniform and uniform luminance surface using the correction coefficient stored in the storage means is made to match the maximum output value in all the focus detection sensors. The automatic focus detection device according to claim 1. 4. The uniformization of all focus detection sensor outputs for a uniform and uniform luminance surface using the correction coefficient stored in the storage means is made to match the minimum output value in all focus detection sensors. The automatic focus detection device according to claim 1. 5. A plurality of focus detection sensors corresponding to a plurality of subject areas in a shooting screen, and a defocus amount for repeatedly detecting a defocus amount of each area based on signals from the plurality of focus detection sensors. Detecting means, selecting means for selecting at least one area of the plurality of subject areas, and focus adjustment of the photographing lens based on the defocus amount obtained by the focus detection sensor corresponding to the selected subject area. In an automatic focus detection device provided with a lens drive means for driving an optical system, a storage control signal input means for inputting a storage control signal shared by the plurality of focus detection sensors, and the selection means. When an arbitrary area is selected, the accumulation control signal from the accumulation control signal input means is sent to the optimum signal for the focus detection sensor corresponding to the selected area. An automatic focus detection device comprising conversion means for converting into a number. 6. The conversion means stores the correction coefficient for each pixel of a predetermined focus detection sensor and the output of the focus detection sensor corresponding to the selected area for each pixel. The automatic focus detection device according to claim 5, further comprising: a calculation unit that performs a calculation with the correction coefficient stored in the storage unit.