JP2756333B2 - Automatic focusing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to automatic focus detection in which a subject in a plurality of areas is captured within a depth based on the amount of defocus at different positions detected in a plurality of different screen areas. The present invention relates to a camera having a device.

[Prior Art] The present applicant has proposed a camera equipped with an automatic focus detection device of the above type as Japanese Patent Application No. 1-76964.

With the automatic focus detection device according to this proposal, an object located in a plurality of different areas can be brought into the depth at a time with respect to each area / object captured on the screen at a time. It is possible to provide a focus detection device.

[Problems to be solved by the invention]

However, in a camera equipped with an automatic focus detection device of the above type, an intermediate value of the difference between the defocus amounts in each region is obtained, and the lens is driven by this intermediate defocus amount,
In addition, since the aperture is adjusted to an aperture value corresponding to the difference in the defocus amount, when the difference in the defocus amount in each region becomes large, the aperture must be set to a small aperture on the narrowing side. For this reason, for example, when it is desired to obtain an appropriate exposure by the program AE, it is necessary to set the shutter time to a long time, which may result in a camera shake photograph.

In addition, since a plurality of regions are both set within the depth as described above, it is difficult for the photographer to know which region has entered the depth.

[Means for solving the problem]

The present invention has been made in view of the above, and independently detects a focus state of an object in a plurality of different areas on a screen, and outputs a signal of a value corresponding to the focus state in each area for each area. A detecting unit to be formed, an area in which a signal of a first value representing a predetermined focus state among signals formed by the detecting unit is formed, and a predetermined range with respect to the first value by the detecting unit. And a region in which a signal indicating the value of is formed, and a position where the object in the selected region is brought into focus together based on a difference between signals from the detection means in the selected region. Focusing means for driving a lens to perform focusing; and providing a signal formed by the detecting means, when there are a plurality of regions indicating values within a predetermined range with respect to the first value. By the matching means, a signal having a larger difference from the first value among the plurality of areas is an object in the area formed by the detecting means and the signal of the first value are detected by the detecting means. By driving the lens to a position where both the object and the object in the area formed by the in-focus state are in focus, it is possible to prevent the inconvenience that the difference in the defocus amount becomes large, When the defocus amount of the range is indicated, it is possible to focus on multiple objects with the maximum defocus amount in the range together, and auto focus to keep as many subjects in focus as possible An adjustment device is provided.

〔Example〕

FIG. 3 is a diagram showing a schematic configuration of a focus detection device employed in the camera according to the present invention.

In the figure, MSK is a field mask, which has a cross-shaped opening MSK-1 at the center and vertically long openings MSK-2 and MSK3 at the peripheral portions on both sides. FLDL is a field lens, corresponding to the three openings MSK-1, MSK-2, and MSK-3 of the field mask,
It consists of three parts FLDL-1, FLDL-2 and FLDL-3.
DP is a stop, and four apertures DP-1a, DP-1b, DP-4a, and DP-4b are provided at the center, one pair at the top, bottom, left, and right. -2a, DP-2b and DP-3a, DP-3b are provided respectively. Each area FLDL-1, FLDL-2, FLDL-3 of the field lens FLDL has these aperture pairs DP-1, DP-4, DP-2, DP-3 near the exit pupil of an objective lens (not shown). It has the function of forming an image. AFL is 4 to 8
AFL-1a, AFL-1b, AFL-4a, AFL-4b, AFL-2a, AFL
-2b, a secondary imaging lens composed of AFL-3a and AFL-3b, which are arranged behind the apertures DP corresponding to the apertures.
SNS is a sensor composed of four pairs of sensor arrays SNS-R, SNS-C, SNS-L, SNS-CH, and is arranged to receive the image corresponding to each secondary imaging lens AFL. .

In the focus detection system shown in FIG. 3, when the focal point of the photographing lens is ahead of the film surface, the subject images formed on each pair of sensor arrays are close to each other, and when the focal point is behind. Means that the subject images are separated from each other. Since the relative positional displacement amount of the subject image has a specific functional relationship with the defocus amount of the photographing lens, if each sensor array pair performs an appropriate calculation on the sensor output, the defocus amount of the photographing lens, A so-called defocus amount can be detected.

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

FIG. 4 shows an arrangement in which the focus detection device having the focus detection system of FIG. 3 is housed in a camera.

In the figure, LNS is a zoom 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 submirror, and MSK.
Is a field mask, ICF is an infrared cut filter, FEDL is a field lens, RM1 and RM2 are first and second reflection mirrors, 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 emission surface AFP-2,
SNS is a sensor having a cover glass SNSCG and a light receiving surface SNSPLN. The prism member AFP has a reflection surface AFP-1 on which a metal reflection film such as aluminum is deposited, and has a function of reflecting a light beam from the secondary imaging lens AFL and deflecting the light to the emission surface AFP-2. I have. SPI is a light emitting diode, LNSA is a gradient index lens array, and LNSB is a light projecting lens.

The light flux of the light emitting diode SPI is reflected on the quick return mirror QRM via the lens array LNSA and the light projecting lens LNSB, and then illuminates the display unit on the reticle FSCRN.

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

In FIG. 2, PRS is a camera control device, which is, for example, a one-chip microcomputer having a CPU (central processing unit), ROM, RAM, and A / D conversion function therein. The microcomputer PRS performs a series of camera operations such as an automatic exposure control function, an automatic focus adjustment function, and film rewinding and rewinding according to the camera sequence program stored in the ROM. For that purpose, microcomputer
PRS is communication signal SO, SI, SCLK, communication selection signal CLCM, CSDR, CD
The DR is used to communicate with a peripheral circuit in the camera body and a control device in the lens to control the operation of each circuit and lens.

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

LCM is a lens communication buffer circuit that supplies power to the lens power supply terminal VL when the camera is operating, and that the selection signal CLCM from the microcomputer PRS has a high potential level (hereinafter referred to as “H” and a low potential level). Is described as "L"), it is a communication buffer between the camera and the lens.

When the microcomputer PRS sets the selection signal CLCM to “H” and sends out predetermined data as a signal SO in synchronization with SCLK, the buffer circuit LCM transmits SCLK, SCLK via the camera-lens communication contact.
Each buffer signal LCK and DCL of SO is output to the lens.
At the same time, a buffer signal of the signal DLC from the lens LNS is output as a signal SI, and the microcomputer PRS inputs the signal SI as lens data in synchronization with SCLK.

DDR is a switch detection and display circuit. It is selected when the signal CDDR is “H” and the microcomputer uses the signals SO, SI, and SCLK.
Controlled by PRS.

When there is a change in the state of the switch group SWS, the DDR sets the IRQ to "L" to notify that the microcomputer PRS switch state has changed. The microcomputer PRS detects a change state of the switch by communicating a switch change state transmission command with the signals SO, SI, and SCLK. When the DDR receives the switch change state transmission command, the DDR outputs the switch change state to the microcomputer PRS and returns the IRQ to “H”.

When the microcomputer PRS receives the display data by communicating the display command and the display data to the DDR using the signals SO, SI, and SCLK, the microcomputer PRS responds to the command to the external display member DSP or the display driving transistor TR-L in the finder. , TR-C, TR-R
Turn ON / OFF.

SW1 and SW2 are switches that are linked to a release button (not shown). SW1 is turned on by pressing the release button in the first stage, and SW2 is subsequently turned on by pressing in the second stage. Microcomputer prs
When SW1 is turned on, photometry and automatic focus adjustment are performed, and when SW2 is turned on, exposure control and subsequent film winding are performed.

The switch SW2 is connected to the "interrupt input terminal" of the PRS, which is a microcomputer. Even when the program is executed when the switch SW1 is turned on, an interrupt is generated by turning on the switch SW2.

MTR1 is a motor for feeding the film, and MTR2 is a motor for the mirror up / down and the shutter spring change. The forward and reverse rotations are controlled by respective drive circuits MDR1 and MDR2.
Signals M1F and M1 input from microcomputer PRS to MDR1 and MDR2
R, M2F, and M2R are motor control signals.

MG1 and MG2 are magnets for starting the leading and trailing shutters of the shutter, respectively, and are energized by signals SMG1 and SMG2 and amplification transistors TR1 and TR2, and the microcomputer PRS controls the shutter.

LPRS is an in-lens control circuit. A signal DCL input to the circuit LPRS in synchronization with LCK is command data from the camera to the photographing lens LNS, and the operation of the lens in response to the command is predetermined. The control circuit LPRS analyzes the command according to a predetermined procedure, and performs the operation of focus adjustment and aperture control, the operation status of each part of the lens (driving status of the focusing optical system, the driving status of the aperture, etc.) and various parameters from the output DLC. (The open F number, the focal length, the amount of defocus, the coefficient of the moving amount of the focusing optical system, etc.) are output.

The LMTR is a motor for moving the focusing optical system in the direction of the optical axis, and this motor is driven under the control of the circuit LPRS.

Therefore, once the focus adjustment command is sent from the camera, the microcomputer PRS, which is the control device of the camera, does not need to be involved in driving the lens at all until the driving of the lens is completed.

When an aperture control command is sent from the camera, a known stepping motor DMTR for driving the aperture is driven in accordance with the number of aperture stages sent simultaneously.

SPC is an exposure control photometric sensor that receives light from the subject through the shooting lens.The output SSPC is input to the analog input terminal of the microcomputer PRS, and after A / D conversion, automatic exposure control is performed according to a predetermined program. Used for

SDR is a drive circuit of the focus detection line sensor device SNS, and is selected when the signal CSDR is "H" and is controlled by the microcomputer PRS using SO, SI, and SCLK.

Signals SEL0 and SEL given from the drive circuit SDR to the sensor device SNS
1 is the signal φSEL0, φSEL1 from the microcomputer PRS itself,
Sensor line pair SNS-R when φSEL0 = “L”, φSEL1 = “L”
When SELSEL0 = “H” and SELSEL1 = “L”, the sensor array pair SNS−
When C is φSEL0 = “L” and φSEL1 = “H”, SNS
-L is set to S when SSEL0 = "H" and SSEL1 = "H".
These signals are used to select NS-CH.

After the accumulation is completed, SEL0 and SEL1 are set appropriately, and then read clock RCK is sent.
The image signals of the sensor column pair selected by (φSEL0, φSEL1) are serially output sequentially from the output VOUT.

The output VIDEO of the sensor drive circuit SDR is an image signal obtained by calculating the difference between the image signal VOUT from the sensor device SNS and the dark current output, and then amplifying the gain with a gain determined by the luminance of the subject. The dark current output is an output value of a light-shielded pixel in the sensor array, and the SDR holds the output in a capacitor according to a signal from the microcomputer PRS, and performs a differential amplification between the output and the image signal. The output VIDEO is input to an analog input terminal of the microcomputer PRS. The microcomputer PRS converts the signal into a digital signal, and sequentially stores the digital value in a predetermined address on the RAM.

The signals / TINTE1, / TINTE2, / TINTE3, and / TINTE4 are signals that are appropriate with the charges accumulated in the sensor array pairs SNS-R, SNS-C, SNS-L, and SNS-CH, respectively, and indicate that the accumulation has been completed. The microcomputer PRS receives this and executes reading of the image signal.

The operation of the sensor drive circuit SDR and the sensor device SNS is disclosed in Japanese Patent Application Laid-Open No. 63-216905 or the like as a focus detection device having two pairs of sensor rows by the present applicant. Detailed description is omitted.

As described above, the microcomputer PRS receives the image information of the subject image formed on each sensor array pair, performs a predetermined focus detection calculation thereafter, and can know the defocus amount of the photographing lens.

FIG. 5 is a block diagram showing the details of the reticle FSCRN shown in FIG. 4. The Fresnel lens FSCRN-
f is provided, and the light diffusing surface FSCRN−
g is formed. Also, three display areas AF on the light exit surface
The display units AFMK-R, AFMK-C, and AFMK-L provided with a display unit composed of MK-R, AFMK-C, and AFMK-L are each provided with a distance measuring range within the photographing screen as shown in FIG. Is displayed, and is composed of a large number of prism assemblies.
At this time, the display units AFMK-R, AFMK-C, and AFMK-L have the ridge lines of the prisms constituting the display units, the Fresnel lens FSCRN-
It is arranged so as to be substantially perpendicular to the ridgeline direction of f.

As a method of illuminating the display units AFMK-R, AFMK-C, and AFMK-L, light beams from the light emitting diodes SPIL, SPIC, and SPIL shown in FIG. 2 are quickly transmitted through the lens array LNSA and the light projecting lens LNB shown in FIG. After the light is guided on the return mirror QRM and reflected by the quick return mirror QRM, a predetermined display unit selected from the display units AFMK-R, AFMK-C, and AFMK-L of the reticle FSCRN is illuminated. ing. Then, the display unit is observed through a finder system together with an object image formed on the focusing screen FSCRN.

FIG. 7 is a flowchart showing the entire sequence of the camera of the present invention. Before giving a detailed description of the present invention, the entire description will be made.

When power is supplied to the camera shown in FIG. 2, the program starts, all RAMs in the microcomputer PRS are cleared, each input / output port is initialized, and the program is controlled from START.

Step 71 SW1 (switch for photometry and automatic focus detection) is O
It is checked whether N has been performed and if ON, the flow branches to step 77; if OFF, the flow branches to step 72.

Step 72 Initialize the parameters of photometry and automatic focus detection.

Step 73 Determine whether the mode switch is ON and switch
Is ON, go to step 74, otherwise go to step 75
Branch to This mode switching switch is a predetermined switch in the switch group SWS in FIG.

Step 74 Mode switching is performed. During mode switching, the mode switching flag is set to ON. The mode state specified by the switching mode switch is set in the RAM in the microcomputer PRS. Also, reset and start the timer. The mode switching flag is released when SW1 is turned on or when the timer is turned off (time-up).

The modes set in this mode setting include AE modes such as TV priority, AV priority manual, depth mode, program mode, one-shot servo AF, and predictive servo AF.
Various state settings such as AF mode, ISO, and AF point switching are set by predetermined switches in a switch group SWS which is turned on / off by manual operation.

Step 75 Determine whether the timer is ON (whether or not the timer is operating). While the timer is running, return to START and set the timer to O
If FF is performed, the process branches to step 76.

Step 76 Erase the display of the camera and set the camera microcomputer to the software standby state. In this software standby state, not only the microcomputer itself but also the clock and other built-in peripheral modules stop functioning, greatly reducing current consumption.However, as long as the specified voltage is applied, registers in the microcomputer PRS and internal RAM Is retained.

To release the software standby state, use switch SW1.
Changes and the mode changeover switch is operated, and when the software standby state is released, the program returns to ST.
Resume control from ART.

Step 77 If the SW1 is ON, the process branches here. In this step, an AF (auto focus) subroutine is executed. This subroutine will be described later.

Step 78 Perform photometry and calculate the exposure control value.

Step 79 As a result of the execution of the AF subroutine in step 77, if it is determined that the object is in focus, the JF flag is set to "H", so branching is performed with the JF flag. If JF = "H" (focus), branch to step 80. If JF = "L" (out of focus), return to START and repeat the loop.

Step 80 If the camera is in focus, it indicates that the camera is in focus (focus indication). Since a distance measurement enable flag, which will be described later, is set to "H" for a distance measurement point within the depth, a superimposed display corresponding to the distance measurement point is performed.

In particular, the superimposed display stores the previous in-focus state, performs only the first in-focus display, and does not perform the second and subsequent displays to reduce the power consumption of the superimposed display.

Step 81 It is determined whether or not SW2 (exposure start switch) is ON. If SW2 is OFF, return to START and repeat the loop. S
If W2 is ON, the process branches to a release sequence (not shown), performs aperture control and shutter control in accordance with the control value determined in step 78, and subsequently performs film feed control, and returns to START.

Next, the AF subroutine will be described with reference to FIG.

Step 88 The AF mode set in step 74 of FIG. 7 is checked, and the routine branches to each routine according to the mode setting.

Step 89 Execute the NOMAL DEPTH subroutine. In this routine, the number of focus points is limited to one, the camera is shaken with respect to the object, the distance is measured, the amount of defocus of each object is determined, and the aperture value is set to an aperture value to bring each object into focus. The focus detection and the lens control of the mode in which is operated are performed.

Step 90 Execute the AUTO DEPTH subroutine. In this routine, the defocus amounts of a plurality of subject areas (ranging points) are obtained, and if there is a subject at each ranging point, the camera is not shaken and the depth of field is calculated at that position to focus on the plurality of subjects. (Note that this mode is called auto depth.) Step 91 The normal AF subroutine is executed. In this routine, the focus is adjusted to a predetermined ranging point or a ranging point selected by the camera.

Step 92 Return to the main routine.

Next, the operation of the auto depth will be described with reference to FIG.

Step 1 It is measured whether or not the execution of the auto depth processing is the first time. If it is the first time, the process proceeds to Step 2; otherwise, the process proceeds to Step 3.

Step 2 Initialize the auto depth parameters and the like.

Step 3 It is checked whether or not the lens is being driven. If the lens is being driven, this step is held. If the lens is not driven, the process proceeds to step 4. Checking whether the lens is being driven is performed by communicating with the lens and checking the state of the lens. The state of the lens is determined by detecting a driving flag LNS-MOVE (a flag set during driving) in the circuit LPRS through the communication.

Step 4 It is determined whether or not the ONE POINT flag has been set. If the ONE POINT flag has been set, the process proceeds to step 23, and if the ONE POINT flag has been reset, the process proceeds to step 5. The ONE PIONT flag is reset in step 2 when auto-depth is possible or when auto-depth processing is performed for the first time as described later, and the process proceeds to step 5 in the first auto-depth processing.

Step 5 Check whether the auto depth processing is completed or not.
Performs by detecting the DEP END flag. If the auto depth is completed, the process proceeds to step 22 and returns. If the auto depth is not completed, the process proceeds to step 6.

Step 6 If the LD-MOVE flag is detected and set, the process proceeds to Step 8; otherwise, the process proceeds to Step 7. As will be described later, this flag LD-MOVE is set when the lens driving distance is long in the previous lens driving. Since the lens is not driven in the first auto-depth processing, the lens is in a reset state and the process proceeds to step 7.

Step 7 DEP whether the lens was moved last time
Judge by MOV flag. When moving the lens (DEP
(MOV = "H") The process branches to step 18, and if not moving, the process branches to (DEP MOV = "L") step 8.

Step 8 Clear the LD-MOVE and DEP-MOV flags and initialize the current distance measurement.

Step 9 The accumulation subroutine for each sensor is called to accumulate each sensor. First, parameters for accumulating sensors are initialized, and accumulation start communication is performed on the sensors to start accumulation of the sensors. When the accumulation of each sensor is completed, the readout clock is output to the sensor and each image signal accumulated by each sensor is output to A /
Read into the microcomputer PRS while performing D conversion. At the same time as reading each image signal, each image signal is corrected, converted into data suitable for distance measurement calculation, and stored in RAM as image data.

Step 10 The image data obtained for each sensor is correlated to obtain a defocus amount, and stored in a predetermined RAM.

Step 11 Call the ATDEP JUDGE subroutine.

FIGS. 1B and 1C show the flow of the ATDEP JUDGE subroutine. When this subroutine is called, step 30 is executed.

Step 30 It is determined whether or not the amount of defocus determined for each sensor is appropriate.

In the present embodiment, a sensor that uses the left side of the screen as a distance measurement area
A state in which focus detection such as low contrast cannot be detected based on image data of each sensor in three areas, SNS-L, a sensor SNS-R having a distance measurement area on the right side, and a sensor SNS-C having a distance measurement area at the center. Is determined for each sensor. As a result, the OK (L) flag is set to “H” when the focus can be detected by the sensor SNS-L, and OK when the focus cannot be detected.
(L) Set the flag to "L". At the same time sensor SNS
The OK (R) flag is set to "H" or "L" for the sensor SNS-C in accordance with the above determination result. Also, clear the ONE POINT flag.

Step 31 Check whether the focus detection is impossible at all the distance measuring points by the above-mentioned flags OK (R), OK (C), and OK (L). When all the focus detection is impossible, proceed to step 47. Otherwise, go to step 32.

Step 32 The flag OK (R), OK (C), or OK (L) is used to determine whether all focus points can be detected. If so, proceed to the label ALL POINT OK. Otherwise, proceed to step ALL. Proceed to 33.

Step 33 The flag is used to determine whether or not only two focus detection points are available. When only two points out of the three distance measurement areas can be detected (when only one point cannot be measured), the process branches to step 34, and when the number of detectable distance measurement points is less than two points, that is, only one point is detected. When the focus can be detected, the flow branches to step 44.

Step 34 The defocus amount at the focus detection point determined to be focus detectable is compared, and the defocus amount indicating the defocus amount to be focused on an object far from the camera is stored in the memory defF. And the symbols (L, C, R) representing the sensor indicating the amount of defocus stored in the defF are input to the memory No-F. The defocus amount indicating the defocus amount to be focused on a subject close to the camera is input to the memory defN,
The symbols (L, C, R) representing the sensor are stored in memory NO-N.
To enter.

Step 35 The absolute value of the difference between the defocus amounts input to the memories defF and defN is obtained. | defF-defN | Step 36 When the above | defF-defN | is larger than the predetermined value, proceed to Step 43, and when | defF-defN | is smaller, the label MID-POINT CALC
Proceed to step 37.

Step 37 The midpoint SL-Def of the defocus amount stored in the memories defF and defN is obtained.

Find the lens drive amount corresponding to SL-Def.

Step 38 The lens driving amount is compared with a predetermined amount. If the lens driving amount is equal to or more than the predetermined amount, the process proceeds to step 40, and if the lens driving amount is less than the predetermined amount, the process proceeds to step 39.

Step 39 Clear the LD-MOVE flag.

Step 40 Set the LD-MOVE flag.

Step 41 The aperture value is calculated. This calculation is performed by dividing the difference defF-defN of the defocus amount by the minimum circle of confusion (35 μm), and the apex value of this value is set as the aperture value AV.

Step 42 Set POS-ATDEP.

If two focus detection points can detect the focus at steps 30, 31, 33, and 34 to 42, the two defocus amounts defN and de
When the intermediate defocus amount SL-Def (the defocus amount indicating the intermediate position of the subject at the two distance measuring points) with fF is obtained, and the lens is driven by the intermediate defocus amount, the two points are put within the depth. The aperture value for At this time,
When the lens driving amount corresponding to the intermediate defocus amount, that is, the driving amount from the current lens position to the intermediate position is large, the flag LD-MOVE is set, and the flag POS indicates that the depth calculation process can be executed. -Instruct in the setting of ATDEP.

In step 38, the magnitude of the lens driving amount is determined. However, instead of the lens driving amount, the magnitude of the intermediate defocus amount SL-Def obtained in step 37 is determined.
9 and 40 branches may be performed.

If the difference of the defocus amount between the two points is larger than the predetermined amount in the processing in step 36, the process proceeds to step 43, where the sensor symbol of the distant ranging point input to the memory No. Clears the OK (R, C, L) flag and treats the sensor at this far distance measuring point as unable to detect focus.

When the difference in the defocus amount between the two points is larger than a predetermined amount, a distant ranging point is treated as incapable of focus detection,
The reason why the depth processing is not performed is that when the difference in the amount of defocus is large, the aperture must be set to a small aperture on the aperture side in order to put both points within the depth. In order to obtain an appropriate exposure, it is necessary to set the shutter time at a low speed, which may result in a camera shake photograph. Therefore, in such a situation, the depth processing is disabled, and the focus adjustment is performed only for the subject on the near side as described later.

Next, the operation when the focus detection is possible for all the distance measuring points in step 32 will be described. In this case, the process proceeds to the label ALL-POINT OK as described above, and the processing after step 51 in FIG. 1C is performed.

Step 51 The order relation of all the distance measuring points is checked.

In the same manner as in step 34, the defocus amount of the distance measuring point farthest from the camera is entered in def-F, and the symbol representing the distance measuring point is entered in No-F. The defocus amount of the closest ranging point from the camera is set to def-N, and the symbol of that ranging point is set to No-
Put in N. The symbol of the ranging point at which the defocus amount at an intermediate distance among the three ranging points is detected is entered into No-M, and the defocus amount is entered into def-M.

Step 52 The difference between the defocus amount of the farthest ranging point and the defocus amount of the closest ranging point is calculated. | defF-def
N | step 53 It is determined whether or not the difference | defF-defN | of this defocus amount is larger than a threshold value. If the threshold value is smaller than the threshold value, auto depth can be performed between the farthest point and the closest point. Therefore, the process proceeds to step 37 to perform the auto depth control during that time, and the above-described processing is executed.

On the other hand, if the difference between the defocus amounts is larger than the threshold value, the flow branches to step 54.

Step 54 The absolute value of the difference between the defocus amount at the intermediate point and the defocus amount at the near point is calculated in order to determine whether auto-depth is possible at a point near the intermediate point. | defM−d
efN | step 55 It is determined whether or not | defM-defN | is within the threshold value, and if it is within the threshold value, the flow branches to step 56. If it is larger than the threshold value, the flow branches to step 57.

Step 56 Since auto-depth is possible at a point close to the intermediate point, the OK (R, C, L) flag of the ranging point indicating the farthest point specified in the memory No. The amount of defocus is replaced with the amount of defocus at a distant place. | defF ← defM | Then, the process proceeds to step 37 to perform the above-described depth processing, execute the auto-depth between the intermediate point and the closest point, and set the object between the intermediate point and the closest point within the depth. Processing is performed.

When | defM−defN | is larger than the predetermined value in step 55, that is, when it is inappropriate to put both the intermediate point and the closest point within the depth, the process proceeds to step 57 as described above.

Step 57 It is determined whether or not the closest distance measuring point is the center distance measuring point based on the content of No-N. That is, if No-N is C, it is the center ranging point, so the process proceeds to step 61. Otherwise, go to step 58.

Step 58 It is determined whether or not auto-deletion can be performed at a point far from the intermediate point. For this determination, the difference | defF−defM | between the defocus amount at the intermediate point and the defocus amount at the far point is calculated.

Step 59 It is determined whether or not the difference between the intermediate point and the far point is within a threshold value. Step if within threshold
Branch to 60, otherwise branch to step 61.

Step 603 The distance measurement was possible at three points, but the auto depth is available when the distance between the intermediate distance measurement point and the farthest distance measurement point is divided. Since the closest ranging point is not used for auto depth, the OK (R, C, L) flag for the sensor specified in memory No.-N is cleared, and the defocus amount of the intermediate ranging point is the closest ranging point. And the processing after step 37 is performed. Therefore, in this case, depth processing is performed to bring the subject between the intermediate point and the far point into the depth.

Step 61 When the auto-depth cannot be performed because the difference between the defocus amounts of the respective distance measuring points is too large, the process branches here.

In this step, OK (R, C, and C) corresponding to the distance measuring sensors at the intermediate point and the far point designated by the memories No. M and No.
L) Clear the flag.

If three points can be measured by the processing of the above steps 51 to 61, if the difference between the amount of defocus for the farthest point and the closest point of the subject is within a predetermined amount, the depth between the far point and the near point is determined. The processing for putting it inside is performed. At this time, if the difference in the amount of defocus is equal to or more than a predetermined amount and the depth processing is determined to be inappropriate, the depth processing is performed on the objects at the intermediate point and the closest point within the depth. If the difference between the defocus amount between the intermediate point and the near point is equal to or greater than a predetermined value,
Except for the case where the near point defocus amount is a defocus from a sensor that measures distance in the central area, depth processing is performed on the objects at the intermediate point and the far point to be within the depth. At this time, when the near point defocus amount is based on the output of the sensor in the central area, focusing is performed based on only the near point defocus amount, as described later. When the near focus defocus amount is based on the output of the sensor in the central area, the reason for prohibiting the depth processing for the far and middle subjects is that the focus is on the subject located at the center of the screen. This is to prevent a so-called centerless photograph that does not fit. Also, when the amount of defocus between the intermediate point and the far point is large, that is, when it is inappropriate to perform the depth processing at any distance measurement point, the focus adjustment is similarly performed for the near-point subject. It will be.

Next, a case where focus detection (distance measurement) is possible for only one point will be described.

 In this case, the process proceeds to step 44 after step 33.

Step 44 Set the defocus amount at the focus detection point at which focus detection was possible to defN.

Step 46 Set the ONE POINT flag.

Step 47 Set the POS-ATDEP flag.

If only one point can be detected, ONE POINT
The flag is set and the POS-ATDEP is cleared, indicating that depth processing was not possible.

Note that, even when the distance measuring points can measure two or three points as described above, the steps 46 and 47 are similarly performed when the auto-depth processing is inappropriate as described above.

Next, returning to FIG. 1A, the operation after the end of the ATDEP JUDGE subroutine will be continued. When the subroutine is completed, the process proceeds to step 12.

Step 12 Even after the execution of the above subroutine, the set OK (R, C, L) flag is detected.

This OK (R, C, L) flag is set when the depth processing for the farthest point and near point is possible, as described above.
When the OK (R), OK (C), and OK (L) flags are all set and the depth processing for the closest point and the intermediate point is possible, the sensor of the ranging area representing the near point and the intermediate point is indicated. Two flags are set, and when depth processing is performed on the intermediate point and the far point, two flags indicating the sensors in the distance measurement area representing the intermediate point and the far point are set, and focusing is performed when the depth processing is not performed. A flag indicating a sensor in one area is set. Therefore, the set flag is detected, and thereafter, in the display operation at the time of focusing executed in step 80 of FIG. 7, the light emitting diodes SPIL, SPIC, and SPIR corresponding to the area indicated by the set flag are turned on, and the Is superimposed on the area.

Step 13 If the ONE POINT flag is “H”, Step 16
If it is "L", the flow branches to step 14.

Step 14 Detect the POS-ATDEP flag and branch with that flag.

If auto-depth is possible, that is, if POS-ATDEP = "H", the flow branches to step 15. If auto-depth is not possible, that is, if POS-ATDEP = "L", the flow branches to step 17.

Step 15 The depth lens drive control is performed. First, the current position of the lens is obtained, and the lens drive amount calculated by the ATDEP-JUDGE subroutine is added thereto, to calculate the target drive position of the lens, and stored in the RAM. After that, it communicates with the lens, tells the lens the target drive position, and the circuit LPRS in the lens
To drive the lens toward the target position. Also DE
Set the P MOV flag.

As described above, in the first AOTO DEP processing, steps 3 to 12 are performed. If it is determined that the depth processing can be performed in the ATDEP JUDGE subroutine in step 12, steps 13, 14, and 15 are executed, and the lens is moved to the target position as described above. The transition is started toward. When the lens drive is started in this way, the AF subroutine returns, and step 7 in FIG.
The AF subroutine is executed again via 8, 79 and 71.
When this AF subroutine (AUTO DEP subroutine) is performed again, the process proceeds to steps 1 and 3, where it is determined whether the lens has moved to the target position. When the lens moves to the target position, the flag LNS-MOVE is cleared and transmitted to the camera. When the lens moves to the target position, the process proceeds to step 4 and proceeds to step 6 via step 5. In step 6, the LD MOVE flag is determined. This flag is set when the lens drive amount is large in the depth processing. When the lens drive amount is large, the processing after step 8 is executed again.

Therefore, as described above, the depth process based on the amount of defocus at each ranging point is performed again, and the lens is driven toward the new target lens position obtained by the process again.

Thereafter, the above operation is repeatedly performed until the lens drive amount in the depth processing becomes equal to or less than a predetermined value.

As described above, when the lens drive amount obtained in the depth processing is large, the reason why the focus is repeatedly detected and the depth processing is executed is that in such a situation, the amount of defocus for at least one of the subjects is large, and the focus detection error is large. Since there is a possibility that an appropriate depth process cannot be executed when the depth is large, the depth process is performed in order to improve the accuracy of the depth process.

On the other hand, as described later, when the lens driving amount obtained by the depth processing is small, the defocus amounts for both objects are substantially equal, and if the depth processing by refocus detection is further repeated, the lens may not stop forever. It is.

If the lens drive amount obtained by the depth processing becomes less than or equal to the predetermined value while the depth processing is being performed in this manner, the flag LD MOVE is cleared, and the process proceeds to steps 7 and 18 after step 6.

In step 18, the difference between the current lens position and the target lens position is obtained. If the two coincide in step 19, the process proceeds to step 20. If not, the process proceeds to step 21.

In step 21, the remaining lens drive amount obtained in step 18 is transmitted to the lens, and the lens is driven by the remaining amount.

In step 20, a flag DEP END and a JF flag indicating that the auto-depth lens driving process has been completed are set.

After executing step 20 in this way, the AOTO DEP subroutine is returned. When steps 78 and 79 in FIG. 7 are executed, the process proceeds to step 80 since the JF flag is set.

In this step 80, it was detected in step 12 described above.
Light emitting diode SPIL, represented by the OK (R, C, L) flag
The SPIC and SPIR are turned on to indicate which area is within the depth in the viewfinder.

Next, the case where the ONE POINT flag is set in the ATDEP JUDGE subroutine will be described.

In this case, step 16 is executed after step 13 in FIG. In step 16, the lens is driven based on the amount of defocus detected in the near point ranging area. After that, when the AUTO DEP subroutine is executed again, steps 23, 24 are executed through steps 1, 3, and 4.

Step 23 Set AVo (open aperture value) as the control aperture value. As the aperture value, an aperture value other than AVo, for example, an aperture value obtained in the AE subroutine based on the photometric output may be used.

Step 24 Normal auto focus processing is performed.
In this normal auto focus processing, focusing is performed based on the amount of defocus in a region of one of the three distance measurement points where focus detection is possible (a region indicating a nearby defocus amount is given priority).

Next, a case where it is determined that focus detection is not possible in all regions will be described.

In this case, since it is detected in step 14 that POS-ATDEP has been reset, step 17 is executed and the NG flag and the DEP-END flag are set.

Therefore, when the AUTO DEP subroutine processing is performed again, the subroutine is returned via step 5, so that
It is held without being driven by a lens.

When the switch SW2 is turned on while each operation is being executed as described above, the operation shifts to a release operation, and an image is taken. In the aperture control at this time, when the auto depth processing is executed, the aperture is controlled to the aperture value obtained in step 41. On the other hand, when the auto depth processing is not performed, for example, the aperture control is performed with the aperture value corresponding to the photometry value obtained in the AE subroutine.

〔effect〕

As described above, according to the present invention, of the defocus amounts in a plurality of regions, a region in which the difference between the defocus amounts in each region falls within a predetermined value is selected, and the region within the depth of the subject in this selected region is selected. And when there are a plurality of such regions, a region having the largest difference in the defocus amount with respect to, for example, the closest subject is selected from among the plurality of regions. Without affecting many subjects, it is possible to make a state in which both subjects are in focus.

[Brief description of the drawings]

1 (a), 1 (b) and 1 (c) are explanatory views showing a flowchart for explaining the operation of the automatic focusing device according to the present invention, and FIG. 2 is a diagram showing the automatic focusing device according to the present invention. FIG. 3 is a circuit diagram showing an embodiment of a camera provided with the camera, FIG. 3 is a configuration diagram showing an example of a focus detection optical system in the automatic focus adjustment device of the present invention, and FIG. 4 is provided with an automatic focus adjustment device according to the present invention. FIG. 5 and FIG. 6 are configuration diagrams showing the optical system of the camera, FIG. 5 and FIG. 6 are configuration diagrams showing the configuration of the display unit on the reticle according to the present invention, and FIG. 7 is the overall operation of the automatic focusing apparatus according to the present invention. FIG. 8 is an explanatory view showing a flow chart for describing
It is explanatory drawing which shows the subroutine in a flowchart. SNS …… Sensor device PRS …… Microcomputer LNS …… Lens device

Claims (2)

(57) [Claims] A detecting means for independently detecting a focus state of an object in a plurality of different areas on a screen and forming a signal of a value corresponding to the focus state in each area for each area; An area in which a signal of a first value indicating a predetermined focus state is formed in the signal formed by the detecting means, and a signal indicating a value within a predetermined range with respect to the first value is formed by the detecting means. The selected area is selected and the lens is driven to a position where the object in the selected area is in focus together based on the signal difference from the detection means in the selected area. And a focusing unit that performs a focusing operation when there are a plurality of regions indicating values within a predetermined range with respect to the first value as signals formed by the detecting unit. In the region, a signal having a larger difference with respect to the first value is an object in a region where the signal of the first value is formed by the detection unit and a signal in a region where the signal of the first value is formed by the detection unit. An automatic focusing device, wherein the lens is driven to a position where both the object and the object are in focus. 2. The automatic focusing apparatus according to claim 1, wherein the signal of the first value is a signal indicating a focus state in which the object is located at a close distance.