JPH03225306A - Automatic focusing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is an automatic focusing system that captures images by keeping objects in multiple areas within the depth of field based on defocus amounts at different positions detected in multiple different screen areas. This invention relates to a detection device.

[Conventional technology]

The present applicant has proposed a camera equipped with the above type of automatic focus detection device in Japanese Patent Application No. 1-76964.

The automatic focus detection device according to this proposal can bring subjects located in multiple different areas into the depth of field at once for each area/subject captured on the screen at once, and has an extremely easy-to-use automatic focus detection device. A focus detection device can be provided.

[Problem that the invention is trying to solve]

However, in the above-mentioned type of automatic focus detection device, the focus detection for each of a plurality of distance measuring points is performed at once, so the lens is driven while repeating the focus detection operation.
If objects in multiple areas are brought into focus, the focus detection results for each area will be different for each focus detection operation, and there is a risk that it will be difficult to identify the focus.

On the other hand, it is also possible to perform the focus detection operation in each area only once and then move the lens to a focused position for subjects in multiple areas based on the results. Since focus detection is performed on the subject, even if one of the subjects moves, the lens position determined based on the previous focus detection result and the subject in each area will both be in focus. There is a possibility that the originally intended focus adjustment cannot be carried out because the focus position is different from the intended focus position.

[Means to solve the problem]

The present invention has been made in view of the above-mentioned matters, and is intended to bring objects in each area into a state that is determined based on the amount of defocus in each area detected by focus detection results in multiple areas. When the defocus amount (lens drive amount) of If this is the case, perform the focusing operation while repeating the focus detection operation described above, while adjusting the defocus amount (lens drive amount) described above.
To provide a device that determines that the defocus amount of each subject is almost the same when is less than a predetermined value, and performs focusing according to the -degree focus detection operation result, assuming that there is no large focus detection error. It is something.

〔Example〕

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

In the figure, MSK is a field mask, with a cross-shaped opening MSK-1 in the center and vertical openings MSK-2 at the periphery on both sides.
, MSK3. FLDL is a field lens, and the three apertures MSK-1, MSK of the field mask
-2, corresponding to MSK-3, three parts FLDL-1
, FLDL-2, and FLDL-3. DP is a diaphragm, and there are a total of four openings DP-1a and DP-1b in the center, one pair each on the top, bottom, left and right.

DP-4a, DP-4b, and 1 in the left and right peripheral areas.
Pair of two apertures DP-2a, DP-2b and DP-3a
.

DP-3b is provided respectively. Each region FLDL-1, FLDL-2°FLDL-3 of the field lens FLDL has a pair of apertures DP-1°DP.
-4, DP-2, and DP-3 in the vicinity of the exit pupil of an objective lens (not shown). AFL: 4 vs. 8 total
Two lenses AFL-1a and AFL-1b.

AFL-4a, AFL-4b, AFL-2a, AFL-
2b.

This is a secondary imaging lens consisting of AFL-3a and AFL-3b, and is arranged behind each aperture of the aperture DP, corresponding to each aperture. SNS has 4 pairs of sensor rows 5NS-R.

The sensor is composed of 5NS-C, 5NS-L, and 5NS-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 in front of the film plane, the subject images formed on each pair of sensor rows are close to each other, and when the focal point is behind the film plane, the subject images are close to each other. In this case, the subject images are separated from each other. This amount of relative positional displacement of the subject image has a specific functional relationship with the amount of defocus of the photographing lens, so if appropriate calculations are performed on the sensor outputs of each pair of sensor rows, the amount of defocus of the photographing lens, It is possible to detect the so-called defocus amount.

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

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

In the figure, LNS is a zoom shooting lens, QRM is a quick return mirror, FSCRN is a focus plate, PP is a pentaprism, EPL is an eyepiece, FPLN is a film surface, and S
M is a submirror, MSK is a field mask, ICF is an infrared cut filter, FEDL is a field lens, RMI,
RM2 is the first. A second reflection mirror, SHMSK is a light-shielding mask, DP is an aperture, AFL is a secondary imaging lens, AFP is a prism member having a reflection surface AFP-1 and an exit surface AFP-2, and SNS is a cover glass 5NSCG and a light-receiving surface 5N.
This is a sensor with SPLN. The prism member AFP has a reflective surface AFP-1 on which a metal reflective film such as aluminum is vapor-deposited, and has the function of reflecting the light beam from the secondary imaging lens AFL and deflecting it to the exit surface AFP2. SPI is a light emitting diode, LNSA is a gradient index lens array, and LNSB is a light projection lens.

The luminous flux of the light emitting diode SPI is transmitted through the lens array LNSA.
After being reflected on the quick return mirror QRM via the projection lens LNSB, the light illuminates the display section on the focus plate FSCRN.

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

In FIG. 2, PH1 is a camera control device, which includes, for example, a CPU (central processing unit), ROM, and RAM.

It is a one-chip microcomputer (hereinafter referred to as microcomputer) that has an A/D conversion function. Microcomputer PR3 is R
A series of camera operations such as automatic exposure control function, automatic focus adjustment function, film winding and rewinding, etc. are performed according to the camera sequence program stored in the OM. For this purpose, the microcomputer PR8 uses communication signals So, SI,
5CLK, communication selection signal CLCM, C3DR, CDD
R is used to communicate with peripheral circuits within the camera body and the control device within the lens, and to control the operation of each circuit and lens.

SO is the data signal output from the microcomputer PR5, SI
is a data signal input to the microcomputer PR8, and 5CLK is a synchronization clock for signals So and SI.

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

The microcomputer PR3 sets the selection signal CLCM to “H” and
When predetermined data is sent as a signal SO in synchronization with CLK, the buffer circuit LCM transmits each buffer signal LCK of 5CLK and So through the camera-lens communication contact.
, DCL is output to the lens. At the same time, lens LN
The buffer signal of the signal DLC from S is output as the signal Sl, and the microcomputer PR3 inputs the signal SI as lens data in synchronization with 5CLK.

DDR is a switch detection and display circuit and the signal CDD
When R is "H", signals So and SI are selected.

Controlled by microcomputer PR5 using 5CLK.

The DDR outputs an IR when there is a change in the state of the switch group SWS.
Q is set to "L" to notify that there has been a change in the state of the microcomputer PRS switch. The microcomputer PR5 has a signal So,
A switch change state transmission command is communicated using SI and 5CLK to detect a switch change state. When the DDR receives the switch change state transmission command, it outputs the switch change state to the microcomputer PR3 and returns the IRQ to "H".

When the microcomputer PR3 receives the display data by communicating the display command and display data to the DDR using the signals So, SI, and 5CLK, the microcomputer PR3 activates the external display member DSP and the display drive transistor TR in the viewfinder according to the command.
-L, TR-C, and TR-R are set to 0N10FF.

SWI and SW2 are switches linked to a release button (not shown), and when the release button is pressed in the first step, SWI is turned on, and when the release button is pressed in the second step, SW2 is turned on. The microcomputer PR5 performs photometry and automatic focus adjustment when SW1 is turned on, and performs exposure control and subsequent film winding when SW2 is turned on.

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

MTRI is for film feeding, MTR2 is for mirror up/
This is a motor for down and shutter charging, and forward and reverse rotation is controlled by respective drive circuits MDR1 and MDR2. Microcomputer PR3 to MDRI, MDR2
Signals MIF and MIR input to the.

M2F and M2R are signals for motor control.

MCI and MG2 are magnets for starting shutter front curtain and rear curtain travel, respectively, and signals SMGI and 5MG2. The amplification transistors TRI and TR2 are energized, and the microcomputer PR8 performs shutter control.

LPR8 is an in-lens control circuit, and LC is connected to this circuit LPR5.
The signal DCL input in synchronization with K is data of a command from the camera to the photographing lens LNS, and the operation of the lens in response to the command is determined in advance.

The control circuit LPR3 analyzes the command according to a predetermined procedure, and outputs the operation of focus adjustment and aperture control, the operation status of each part of the lens (driving status of the focusing optical system, driving status of the diaphragm, etc.) and various parameters from the output DLC. (Open F number, focal length, coefficient of defocus amount vs. movement amount of the focusing optical system, etc.) are output.

LMTR is a motor that moves the focusing optical system in the optical axis direction, and this motor is driven under the control of the circuit LPR3.

Therefore, once the focus adjustment command is sent from the camera, the microcomputer PR5, which is the camera control device, controls all lens driving (
No need to get involved.

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

SPC is a photometric sensor for exposure control that receives light from the subject through the photographic lens, and its output 5SPC is input to the analog input terminal of microcomputer PR5, and after A/D conversion, automatic exposure control is performed according to a predetermined program. used for.

SDR is a drive circuit for the focus detection line sensor device SNS, and is selected when the signal C3DR is “H”.
Controlled by microcomputer PR5 using o, SI, and 5CLK.

Signal 5E given from drive circuit SDR to sensor device SNS
LO, 5ELI is the signal φ5ELO from the microcomputer PR8
, φ5ELI itself, φ5ELO="L"φ5EL
When 1="L", sensor row pair 5NS-R is set to φ5ELO
When = “H” and φ5EL1 = “L”, sensor row pair 5NS
-C, φ5ELO=“L”, sensor row pair 5NS-L when φ5EL1=“H”, φ5ELO=“H”, φ5E
This is a signal that selects the sensor row pair 5NS-CH when Ll="H".

After the accumulation is completed, set 5ELO and 5ELI appropriately,
Then by sending the read clock RCK, 5
The image signals of the pair of sensor rows selected by ELO, 5ELI (φ5ELO, φSEL 1 ) are serially output from the output VOUT.

The output VIDEO of the sensor drive circuit SDR is an image signal obtained by taking the difference between the image signal VOUT from the sensor device SNS and the dark current output, and then amplifying the difference with a gain determined by the brightness of the subject. The above-mentioned dark current output is the output value of the light-shielded pixels in the sensor array, and SDR is the output value of the light-shielded pixels in the sensor array.
The output is held in a capacitor by the signal from the image signal, and differential amplification is performed between this and the image signal. The output VIDEO is input to the analog input terminal of the microcomputer PR3, and the microcomputer PR5 converts the signal from analog to digital and sequentially stores the digital values at predetermined addresses on the RAM.

Signals /TINTEI, /TINTE2. /TINTE3
゜/TINTE4 is sensor row pair 5NS-R, 5 respectively
This is a signal indicating that the charges accumulated in NS-C, 5NS-L, and 5NS-CH are appropriate and the accumulation has been completed. Upon receiving this signal, the microcomputer PR3 executes reading of the image signal.

The operations of the sensor drive circuit SDR and the sensor device SNS have been previously disclosed by the present applicant in Japanese Patent Application Laid-Open No. 63-216905 as a focus detection device having two pairs of sensor arrays, so details will be described here. Further explanation will be omitted.

As described above, the microcomputer PR3 receives the image information of the subject image formed on each pair of sensor rows, and then performs a predetermined focus detection calculation, thereby being able to determine the amount of defocus of the photographing lens.

FIG. 5 is a detailed configuration diagram of the focus plate FSCRN shown in FIG. g is formed.

There are also three display sections AFMK-RXAFMK on the light exit surface.
The display units AFMK-R, AFMK-C, and AFMK-L, which are provided with display bodies consisting of -C and AFMK-L, each display an area indicating the ranging range within the shooting screen, as shown in Figure 6. It is composed of a large number of prism aggregates. At this time, the display parts AFMK-R, AFMK-C, AF
MK-L is arranged so that the ridgeline of the prism constituting the display section is substantially perpendicular to the ridgeline direction of the Fresnel lens FSCRN-f.

The lighting method for the display section AFMK-RSAFMK-CSAFMK-L is the light emitting diode 5PIL shown in the second figure.

The light flux from 5PICSSPIL is guided onto the quick return mirror QRM via the lens array LNSA and the light projection lens LNB shown in Fig. 4, and the light flux from the quick return mirror Q
After reflecting with RM, display part AFM of focus plate FSCRN
A predetermined display section selected from among K-R, AFMK-C, and AFMK-L is illuminated. The display unit is then observed through a finder system together with the object image formed on the focusing plate FSCRN.

FIG. 7 is a flowchart showing the entire sequence of the camera of the present invention, and the entire sequence will be explained before giving a detailed explanation of the present invention.

When the power is turned on to the camera shown in the second figure, the program starts, all RAM in the microcomputer PR3 is cleared, each input/output board is initialized, and the program is 5TAR.
Controlled from T.

Step 71SW1 (photometering, automatic focus detection switch)
is ONL, and if it is ON, the process branches to step 77; if it is OFF, the process branches to step 72.

Step 72 Initialize parameters for photometry and automatic focus detection.

Step 73 It is determined whether the mode switching SW is ON. If the switching SW is ON, the process proceeds to Step 74; otherwise, the process branches to Step 75. This mode changeover switch is a predetermined switch in the switch group SWS shown in FIG.

Step 74 Perform mode switching. During mode switching, the mode switching flag is set to ON. The mode state specified by the changeover mode switch is set in the RAM in the microcomputer PR8. Reset and start the timer again. The mode switching flag is cleared when the SWI is turned on or when the timer turns 0FF (times up).

The modes set in this mode setting include AE modes such as TV priority, AV priority manual, depth mode, program mode, AF modes such as one-shot servo AF, predictive servo AF, various types such as 15O1 AF point switching, etc. The state is set using a predetermined switch in the switch group SWS that is manually turned on and off.

Step 75: Determine whether the timer is ON (operating or not). While the timer is running, it returns to 5TART,
If the timer is OFF, the process branches to step 76.

Step 76: Turn off the camera display, etc., and put the camera microcomputer into software standby mode. In this software standby state, current consumption is significantly reduced because not only the functions of the microcomputer itself (including the clock and built-in peripheral modules) are stopped, but as long as the specified voltage is applied, the registers in the microcomputer PR3 and the built-in RA
The data of M is retained.

To cancel the software standby state, use the switch SWI
The program resumes control from 5TART when the software standby state is released.

Step 77 If SWI is turned on, the process branches to this point. In this step, an AF (autofocus) subroutine is executed. This subroutine will be described later.

Step 78: Perform photometry and calculate exposure control value.

Step 79 As a result of the AF subroutine execution in step 77, if it is determined that the focus is in focus, the JF flag is set to "H", so branching is performed using the JF flag.JF="H"
” (in focus), branch to step 80.

If JF-“L” (out of focus), return to 5TART and repeat Lube.

Step 80 If the camera is in focus, display that it is in focus (focus display). Since the ranging point that is within the depth has a ranging enable flag (described later) set to "H", a superimposed display corresponding to that ranging point is performed.

In particular, the power consumption of superimposed display is reduced by memorizing the previous focusing state, performing it only the first time, and not displaying it from the second time onwards.

Step 81 It is determined whether SW2 (exposure start switch) is ON. If SW2 is OFF, return to 5TART and repeat the loop. If SW2 is ON, the program branches to a release sequence (not shown), performs aperture control and shutter control in accordance with the control values determined in step 78, then performs film feeding control, etc., and returns to 5TART.

Next, the AF subroutine will be explained using FIG. 8.

Step 88 A set in step 74 of FIG.
Checks the F mode and branches to each routine according to the mode setting.

Step 89 Execute the NOMAL DEPTH subroutine. In this routine, the distance measurement point is limited to one, the camera is swung toward the subject, the distance is measured, the amount of defocus for each subject is determined, and the aperture value is set to bring each subject into focus. Performs focus detection and lens control for camera operating modes.

Step 90 Execute the AUTODEPTH subroutine. This routine uses multiple subject areas (focus points).
If there is a subject at each distance measurement point, the depth of field is calculated at that position without shaking the camera, and multiple subjects are focused.

(This mode is called auto depth) Step 91
A normal AF subroutine is executed.

In this routine, the camera focuses on one distance-measuring point specified in advance or a distance-measuring point selected on the camera side.

Step 92: Return to the main routine.

Next, the operation of auto-depth will be explained according to FIG. 1(a).

Step 1 Determine whether or not the auto-depth processing is being executed for the first time. If it is the first time, proceed to step 2; if not, proceed to step 3.

Step 2 Initialize auto depth parameters, etc.

Step 3 Check whether the lens is being driven or not. If it is being driven, this step is held; if it is not being driven, proceed to Step 4. Checking whether the lens is being driven or not is performed by communicating with the lens and checking the state of the lens. The state of this lens is determined by detecting the driving flag LMS-MOVE (a flag set during driving) in the circuit LPR3 through the above communication.

Step 4 Determine whether the ONE POINT flag is set, and if it is set, step 23
If it has been reset, proceed to step 5.

As will be described later, the ONE PIONT flag is reset in step 2 above when auto-depth is possible or when auto-depth processing is executed for the first time, and the process proceeds to step 5 in the first auto-depth processing.

Step 5: Detect whether the auto-depth processing has ended or not by detecting the DEP END flag. If the auto-depth has been completed, the process proceeds to step 22 and returns; if the auto-depth has not been completed, the process proceeds to step 6.

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

Step 7 DEP to see if the lens was moved last time
Determine using the MOV flag. If the lens is moving (OEP MOV="H"), the process branches to step 18; if the lens is not moving, the process branches to step 8 (DEP MOV="L").

Step 8 LD-MOVE, DEP-MOV7 Clear the lag and initialize the current distance measurement.

Step 9: Call the storage subroutine for each sensor to perform storage for each sensor. First, parameters for accumulating the sensor are initialized, and an accumulation start communication is sent to the sensor to start accumulating the sensor. When the accumulation of each sensor is completed, a readout clock is output to the sensor and each image signal accumulated by each sensor is output to the A/
Load it into the microcomputer PR3 while converting it to D. At the same time as reading each image signal, each image signal is corrected and converted into data suitable for distance measurement calculation, and stored in the RAM as image data.

Step IO A correlation calculation is performed on the image data obtained for each sensor to obtain respective defocus amounts, and these are stored in a predetermined RAM.

Step 11 Call the ATDEP JUDGE subroutine.

Figure 1 (b) and (C) are ATDEP JUDGE
It shows the flow of a subroutine. When this subroutine is called, step 30 is executed.

Step 30: It is determined whether the defocus amount obtained for each sensor is appropriate.

In this embodiment, the sensor 5 uses the left side of the screen as the ranging area.
NS-L, sensor 5NS-R with distance measurement area on the right side
, based on the image data of each sensor in three areas of the sensor 5NS-C whose distance measurement area is the central part, it is determined for each sensor whether there is a state in which focus cannot be detected due to low contrast or the like. As a result, when the sensor 5NS-L can detect the focus, the OK (L) flag is set to "H", and when the focus cannot be detected, the OK (L) flag is set to "L". Similarly, the OK (R) flag for sensor 5NSR and the OK (C) flag for sensor 5NS-C are set to "H" or "L" according to the above determination results. Also, clear the 0NEPOINT flag.

Step 31 Check whether focus cannot be detected at all of the distance measuring points using the flags OK (R), OK (C), and OK (L). If focus cannot be detected at all of the points, step 47
Otherwise, proceed to step 32.

Step 32 Flag OK (R), OK (C),
At 0K (L), determine whether all focus points can be detected, and if possible, label ALL POINT.
Proceed to OK; otherwise, proceed to step 33.

Step 33: It is determined from the above flag whether or not there are only two focus detection points. If only two points out of the three distance measurement areas can be detected (when only one cannot be measured), the process branches to step 34, and if the number of detectable distance measurement points is less than two, that is, only one point is detected. When focus can be detected, step 44
Branch to.

Step 34 Compare the defocus amounts at the distance measuring points determined to be able to detect the focus, and defocus the one whose defocus amount indicates the defocus amount for focusing on a subject that is far away from the camera. The symbol (L) represents a sensor that stores the defocus amount in the memory defF and indicates the defocus amount stored in this defF.

C, R) into memory No-F. Enter the defocus amount that indicates the defocus amount for focusing on a subject close to the camera into the memory defN, and set the symbol (L, C, R) representing that sensor to the memory No.
Enter -N.

Step 35 Find the absolute value of the difference between the defocus amounts input into the memories defF and defN.

defF-defN Step 36 When the above 1defF-defN l is larger than a predetermined value, the process proceeds to step 43, and when it is small, the process proceeds to step 37 of the label MID-POINT CALC.

Step 37 Find the midpoint 5L-Def of the defocus amounts stored in the memories defF and defN.

The lens driving amount corresponding to 5L-Def is determined.

Step 38 The lens drive amount is compared with a predetermined amount, and if the lens drive amount is greater than or equal to the predetermined amount, the process proceeds to step 40, and if it 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 Calculate the aperture value. This calculation calculates the above defocus amount difference defF-defN to the circle of least confusion (3
5 μm), and the apex value of this value is taken as the aperture value AV.

Step 42 Set PO3-ATDEP.

In steps 30.31.33.34 to 42 above, when the two distance measuring points can detect focus, the intermediate defocus amount 5LDef between the defocus amount defN and defF of the two points
(defocus amount representing the intermediate position of the object between the two distance measurement points) is determined, and when the lens is driven by the intermediate defocus amount, the aperture value for bringing the two points within the depth of field is determined. At this time, when the lens drive amount corresponding to the intermediate defocus amount, that is, the drive amount from the current lens position to the above intermediate position was large, the flag LD-MOVE was set, and depth calculation processing could be executed. This is indicated by setting the flag POS-ATDEP.

Incidentally, in step 38, the magnitude of the lens driving amount is determined, but instead of the lens driving amount, the intermediate defocus amount 5L-Def obtained in step 37 is determined, and the branching of step 39.40 is made. You may do so.

If the difference in defocus amount between the two points is larger than the predetermined amount in the process of step 36 above, the process proceeds to step 43, and the sensor of the distant distance measurement point input into the memory No-F in step 34 above Symbol OK (R, C.

L) Clear the flag and treat the sensor at this distant distance measuring point as unable to detect focus.

When the difference in defocus amount between the two points is larger than a predetermined amount, the reason why the distant focus point is treated as undetectable and the depth processing is not executed is because of the difference in defocus amount described above. In order to bring both points within the depth of field when is large, the aperture must be set to a small aperture on the narrowing side.
For example, in order to obtain proper exposure during exposure control, it is necessary to set the shutter speed to a low speed, which may result in a shaky photograph. Therefore, under such a situation, depth processing is disabled and focus adjustment is performed only for the closest subject (as will be described later).

Next, the operation when focus detection is possible at all distance measuring points in step 32 will be explained. In this case, proceed to the label ALL-POINT OK as described above and see Figure 1 (c).
The processing from step 51 onwards is performed.

Step 51 Check the order relationship of all distance measurement points.

Similarly to step 34 described above, the defocus amount of the distance measurement point farthest from the camera is entered into def-F, and the symbol representing that distance measurement point is entered into No-F. Enter the defocus amount of the distance measurement point closest to the camera into def -N, and the symbol of that distance measurement point into No-N. The symbol of the distance measuring point where the defocus amount at the middle distance among the three distance measuring points was detected is entered into No-M, and the defocus amount is entered into def-M.

Step 52: Calculate the difference between the defocus amount of the farthest distance measuring point and the defocus amount of the closest distance measuring point. defF
-defN Step 53 This difference in defocus amount is 1defF-
Determine whether defN1 is greater than a threshold.

If it is smaller than the threshold, auto-depth is possible between the farthest point and the nearest point, so the process proceeds to step 37 to perform auto-depth control between the farthest point and the nearest point, and the above-mentioned process is executed.

On the other hand, if the difference in defocus amount is greater than the threshold value, the process branches to step 54.

Step 54: In order to determine whether auto-depth is possible at a point close to the intermediate point, the absolute value of the difference between the defocus amount at the intermediate point and the defocus amount at the near point is calculated. ld
efM-defN Step 55 l defM-defN It is determined whether l is within a threshold value. If it is within the threshold value, the process branches to step 56, and if it is larger than the threshold value, the process branches to step 57.

Step 56 Since auto-depth is possible at a point close to the intermediate point, clear the OK (R, C, L) flag of the distance measuring point that represents the farthest point specified in memory No. Replaces the defocus amount with the distance defocus amount. 1defF←def M After that, the process moves to step 37, where the depth processing described above is performed, the auto depth between the intermediate point and the closest point is executed, and the process is performed to bring the subject between the intermediate point and the closest point into the depth of field. will be done.

If l defM-defN l is larger than the predetermined value in step 55, that is, if it is inappropriate to enter the deep change direction between the intermediate point and the closest point, the process proceeds to step 57 as described above.

Step 57: Determine whether or not the closest distance measuring point is the central distance measuring point based on the content of No-N. Namely, N.

If N is C, it is the central distance measurement point, and the process proceeds to step 61. Otherwise, the process proceeds to step 58.

Step 58 Determine whether auto-depth can be performed at the intermediate point and the far point. For this determination, the difference between the defocus amount at the intermediate point and the defocus amount at the far point I defF-de
Calculate fM l.

Step 59: Determine whether the defocus difference between the intermediate point and the far point is within a threshold value. If it is within the threshold value, the process branches to step 60; otherwise, the process branches to step 61.

Although distance measurement was possible at step 603, auto-depth is possible between the distance measurement point at the intermediate distance and the distance measurement point at the farthest distance.

The closest AF point is not used for auto depth, so OK is applied to the sensor specified by memory No.
The (R, C, L) flag is cleared, the defocus amount of the intermediate distance measuring point is substituted for the defocus amount of the closest distance measuring point, and the processing from step 37 onwards is performed.

Therefore, in this case, depth processing is performed to bring the subject between the intermediate point and the far point within the depth of field.

Step 61 If the difference in defocus amount between each distance measurement point is too large to enable automatic depth, branch here (
Ru.

In this step, OK is selected corresponding to the intermediate point and far point distance measurement sensor specified by memory No.MS No.F.
Clear the (R, C, L) flag.

If 3-point distance measurement is possible through the processing in steps 51 to 61 above, if the difference in defocus amount for the object at the farthest point and the closest point is within a predetermined amount, the distance between the far point and the near point is Processing is performed to keep it within the depth. At this time, if the difference in the defocus amount is greater than or equal to a predetermined amount and it is determined that depth processing is inappropriate, depth processing is performed on the subject at the intermediate point and the closest point to bring it within the depth of field. If the difference between the defocus amount between the intermediate point and the near point is more than a predetermined value, the difference between the intermediate point and the near point will be different from the intermediate point, unless the defocus amount at the near point is the defocus from the sensor measuring the distance in the central area. Depth processing is performed on the subject at the far point to keep it within the depth of field. At this time, if the defocus amount at the near point is based on the output of the sensor in the central region,
Focusing is performed based only on the amount of defocus at this near point. The reason why depth processing is prohibited for objects at the far point and intermediate point when the defocus amount at the near point is based on the output of the sensor in the central area is that This is to prevent so-called blank photos where the images do not match. Also, when the amount of defocus between the intermediate point and the far point is large, that is, when it is inappropriate to perform depth processing no matter which focusing point is taken, focus adjustment is also performed on the subject at the near point. It will be done.

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

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

Step 44: Set the defocus amount at the distance measurement point where focus detection was possible to defN.

Step 46 Set the ONE POINT flag.

Step 47 Set the PO3-ATDEP flag.

If only one point can be detected in focus like this, 0NEPOI
The NT flag is set and POS-ATDEP is cleared to indicate that depth processing is not possible.

Incidentally, even when two or three distance measurement points are possible as described above, if the auto depth processing is inappropriate as described above, the processing of steps 46 and 47 is performed in the same manner.

Next, return to Figure 1(a) and select ATDEP JUDGE.
We will continue to explain the operation after the subroutine ends. Upon completion of this subroutine, the process proceeds to step 12.

Step 12 Detects the OK (R, C, L) flag that is set even after the execution of the above subroutine.

As mentioned above, the OK (R, C, L) flags that are set are all set when depth processing is possible for the farthest point and the closest point. When depth processing is possible for the closest point and intermediate point, two flags indicating the sensors in the ranging area representing the near point and intermediate point are set, and depth processing is performed for the intermediate point and far point. Sometimes, two flags are set indicating the sensors in the ranging area representing the intermediate point and the far point, and when depth processing is not performed, a flag indicating the sensor in one area for focusing is set. Therefore, this set flag is detected, and then the seventh
In the display operation at the time of focusing executed at step 80 in the figure,
The light emitting diodes 5PIL, 5PIC, and 5PIR corresponding to the area indicated by this set flag are lit, and the area is superimposed in the viewfinder.

Step 13 ONE POINT flag is “H”
If so, branch to step 16; if “L”, step 1
Branch to 4.

Step 14 Detect the PO5-ATDEP flag,
Branch on that flag.

If auto-depth is possible, that is, PO8-ATDEP="
If auto-depth is not possible, that is, if PO3-ATDEP="L", the process branches to step 17.

Step 15: Perform depth lens drive control.

First, find the current position of the lens, and then use ATDEP-JU.
Add the lens drive amount calculated by the DGE subroutine,
The target drive position of the lens is calculated and stored in RAM. Thereafter, communication with the lens is performed, the target driving position is transmitted to the lens, and the lens is driven toward the target position using a circuit LPR3 inside the lens. Also, set the DEP MOV flag.

As mentioned above, in the first AOTODEP process, step 3~
ATDEP JUD at step 12
If it is determined in the GE subroutine that depth processing is possible, steps 13, 14, and 15 are executed, and the lens begins to move toward the target position as described above.

When lens driving is started in this way, the AF subroutine is returned and the AF subroutine is executed again via steps 7B and 79.71 in FIG. When this AF subroutine (AUTODEP subroutine) is executed 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-MOV is activated.
Since E is cleared and transmitted to the camera, when the lens moves to the target position, the process proceeds to step 4, and then proceeds to step 6 via step 5. In step 6, the LDMOVE flag is determined. This flag is set when the lens driving amount is large during depth processing, and when the lens driving amount is large, the processing from step 8 onwards is executed again.

Therefore, as described above, the depth processing is performed again based on the defocus amount at each distance measurement point, and the lens is driven toward the new target lens position determined by this processing again.

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

In this way, when the lens drive amount determined by depth processing is large,
The reason for repeating focus detection and executing depth processing is that in such a situation, the amount of defocus for at least one subject is large, and there is a risk that appropriate depth processing may not be executed when the focus detection error is large. This is done to improve the accuracy of depth processing.

On the other hand, as described later, if the lens drive amount determined by depth processing is small, the amount of defocus for both wave objects is almost equal, and if depth processing by refocusing detection is repeated any further, the lens will not stop forever. This is because there is a risk.

While the depth processing is being performed in this manner, if the lens drive amount determined by the depth processing becomes less than or equal to a predetermined value, the flag LD MOVE is cleared, so the process proceeds to step 7.18 following step 6.

In step 18, the difference between the current lens position and the target lens position is determined, and in step 19, if they match, the process proceeds to step 20, and if they do not, the process proceeds to step 21.

In step 21, the remaining lens drive amount determined 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 AOTODEP subroutine is returned, and when steps 78 and 79 in FIG. 7 are executed, the JF flag is set, so the process proceeds to step 80.

In step 80, the light emitting diodes 5PIL, 5PIC, and 5PIR indicated by the OK (R, C, L) flags detected in step 12 are turned on to display which area is within the depth in the finder. .

Then, it is set to 0N in the ATDEP JUDGE subroutine.
The case where the EPOINT flag is set will be explained.

In this case, step 16 is executed after step 13 in FIG. 1(a). In step 16, the lens is driven based on the amount of defocus detected in the distance measurement area at the near point. Then, when the AUTODEP subroutine is executed again, step 23.2 is executed via step 1.3.4.
4 is executed.

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

Step 24 Normal autofocus processing is performed. In this normal autofocus processing, focusing is performed based on the amount of defocus in the area of one point among the three distance measurement points where focus can be detected.

Next, a case where it is determined that focus detection is not possible in the entire area will be explained.

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 DEP-END flag are set.

Therefore, when processing the AUTODEP subroutine again, the subroutine is returned through step 5, so that the lens is held without being driven.

When the switch SW2 is turned on while each operation is being executed as described above, the camera shifts to the release operation and takes a picture. In this case, the aperture is controlled to the aperture value determined in step 41 when the auto-depth processing is executed. On the other hand, when auto-depth processing is not performed, aperture control is performed using an aperture value that corresponds to the photometric value obtained, for example, in the AE subroutine.

〔effect〕

As described above, in the present invention, when the amount of lens drive based on the depth calculation result is large, focus adjustment for depth processing is performed instead of repeating the focus detection operation, and when the amount of lens drive on the - side is small, the focus is detected at that time. Since the focus was adjusted based on the results, it is possible to adjust the focus with high precision and at high speed.

[Brief explanation of drawings]

FIGS. 1(a), (b), and (c) are explanatory diagrams showing flowcharts for explaining the operation of the automatic focus adjustment device according to the present invention, and FIG. FIG. 3 is a configuration diagram showing an example of a focus detection optical system in an automatic focus adjustment device of the present invention, and FIG. 4 is a circuit diagram showing an example of a camera equipped with an automatic focus adjustment device of the present invention. FIGS. 5 and 6 are block diagrams showing the structure of the display section on the focus plate in the present invention, and FIG. 7 shows the overall operation of the automatic focusing device according to the present invention. Explanatory diagram showing a flowchart for explaining, No. 8
This figure is an explanatory diagram showing a subroutine in the flowchart of FIG. 7. SNS...Sensor device PH1...Microcomputer LNS...Lens device Diagram 1

Claims (1)

[Claims] (1) A defocus amount detection circuit that independently detects the defocus amount in different subject areas, and at least one for bringing the subject in at least two areas within the depth of field based on each defocus amount detected by the defocus amount detection circuit. an arithmetic circuit that calculates an intermediate defocus amount of the defocus amounts in the two regions; a lens drive circuit that drives the intermediate defocus amount lens calculated by the arithmetic circuit; and a defocus amount detection circuit when the intermediate defocus amount is equal to or greater than a predetermined value. The system repeatedly detects the amount of defocus and performs arithmetic processing using the arithmetic circuit.
On the other hand, an automatic focus adjustment device comprising a control circuit that prohibits the intermediate defocus amount and the repetition of the calculation process by the calculation circuit when the intermediate defocus amount is less than a predetermined value.