JPH03211516A - 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] [Industrial Application Field] The present invention relates to an automatic focus adjustment device that adjusts the focus of a photographic lens by detecting the amount of defocus of a plurality of subject areas within the screen of a photographic lens. It is.

[Prior Art] Conventionally, a focus detection device for a camera focuses light beams from a subject that have passed through different exit pupil areas of a photographic lens on a pair of line sensors, and photoelectrically converts the subject image. A well-known method is to detect the amount of defocus of a subject by determining the amount of relative positional displacement of a pair of image signals.

In the above method, only one set of focus detection system (optical system, sensor) is required, so it can only detect the defocus amount of one subject area on the screen. However, by preparing multiple sets of detection systems, it is possible to detect Many methods for detecting the amount of defocus have also been proposed.

In the latter method, since there are a plurality of subject areas, there are also a plurality of detected defocus amounts. However, the number of subject areas that you want to focus on with the camera is ultimately one, or at most two areas (in this case, for example, focus on an intermediate value between the two), so you have to follow some procedure to select the subject area. Then, the photographic lens is focused with the amount of defocus corresponding to the selected area.

A common selection method is to select a subject area that is determined to be closest to the camera.

[Problem that the invention is trying to solve]

However, the above selection method may cause the following inconvenience.

In other words, a focus detection operation is performed at a certain shooting lens position, one area is selected from among multiple subject areas, the shooting lens is driven with the amount of defocus for that area, and the focus detection operation is performed again at the distance ring position where lens driving is completed. When performing a focus detection operation, depending on the subject situation, the previously selected area may become undetectable, and another area from among the subject areas for which focus can be detected may be reselected, and the lens may be adjusted again using the amount of defocus in that area. A case may occur in which driving is performed. Then, after lens driving is completed again, the area selected first for focus detection becomes focus detectable, and instead, the area selected last time becomes undetectable, and lens driving is performed again. This is repeated a considerable number of times, and the driving of the photographic lens becomes, so to speak, in an oscillating state.

[Means to solve the problem]

SUMMARY OF THE INVENTION An object of the present invention is to provide an automatic focusing device that solves the above-mentioned problems and suppresses defective lens drive operations.

In order to achieve the above object, the present invention stores past focus detection enablement/disability for each of a plurality of subject areas, and - if a star becomes detectable and then becomes undetectable,
Thereafter, while the release button is turned on, even if detection becomes possible again, the automatic focus adjustment device is treated as undetectable, and the above-mentioned malfunction of the lens is suppressed. It is something.

〔Example〕

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

FIG. 1 is a flowchart showing an outline of an embodiment of the present invention, and the operation will be explained using this flowchart.

In step (001), focus detection is performed on a plurality of subject areas on the screen, and the amount of defocus for each area is detected.

The next step (002) represents a loop process in which processing is performed for each of the four subject areas of this embodiment, and the process is performed while changing the argument i representing the area from 1 to 4.

First, set the argument i to 1 and proceed to step (003).

In step (003), it is determined whether focus detection is possible for area i, that is, object area 1, and if it is not possible, the process moves to step (004).

In step (004), it is determined whether or not focus detection was once possible for area l in the past, and if not, the lube process of step (002) for object area 1 is terminated.

In step (004), if the area 1 has been once focus detectable in the past, the process moves to step (005), where it is stored that the area 1 has become incapable of being detected after once being possible, and the loop processing is ended.

If the focus of the subject area l is detectable in step (003), the process moves to step (006).

In step (006), it is determined whether or not area 1 was once focus detectable in the past but has become impossible. If so, the process moves to step (007), The loop processing is terminated by treating l as being unable to detect the focus.

When the loop processing for object region 1 is completed, the argument i representing the region is set to 2, and the loop processing from step (003) onwards is performed.

When the loop processing for area 2 is completed, processing is subsequently performed for area 3.4, and when the loop processing for all subject areas is completed, step (002) is ended.

By processing in this way, even if the sensor in the area that was once unable to detect focus becomes able to detect focus, it will be treated as disabled, so the oscillation operation caused by the sensor in the same area repeatedly being able to detect focus and not being able to detect focus will be prevented. It is intended to prevent

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

In the figure, MSK is a field mask, with a cross-shaped opening MSK-1 in the center and vertical openings MSK-1 at the periphery on both sides.
2, has MSK3. FLDL is a field lens, and the three openings MSK1, MSK of the field mask
-2, corresponding to MSK-3, three parts FLDL-1
, FLDL-2, and FLDL-3. DP is an aperture, and in the center there are a total of four openings DP-1a, DP-1b, DP-1c, and D.
P-1d, and a pair of two openings D in the left and right peripheral areas.
P-2a, DP-2b and DP-3a, DP-3b are provided, respectively. The field lens FLDL
Each area FLDL-1, FLDL-2°FLDI, -3
are these aperture pairs DP-1, DP2, and DP-3, respectively.
It has the function of forming an image near the exit pupil of an objective lens (not shown). AFL has 4 pairs of lenses in total, AFL-1a,
AFL-1b, AFL-4a, AFL4b, AFL-
This is a secondary imaging lens consisting of XAFL-3a and AFL3b, and is arranged behind each aperture of the aperture DP. SNS has 4 pairs of 8 sensor rows 5NS-1a and 5NS-1b.

SNS 4a, SNS 4b, SNS 2a, 5
NS-2b.

The sensor is composed of 5NS-3a and 5NS-3b, and is arranged so as to correspond to each secondary imaging lens AFL and receive its image.

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 out-of-focus of the photographing lens, so if appropriate calculations are performed on the sensor output of each pair of sensor rows, the amount of defocus of the photographing lens can be calculated. , so-called defocus amount can be detected.

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. 2 is a circuit diagram showing an example of a specific configuration of a camera equipped with a focus detection device as shown in FIG. 3. 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 PRS 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 PR3 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 PR3, and 5CLK is a synchronization clock for signals So and Sl.

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 PR3 is set to a high potential level (hereinafter referred to as "H", low potential level). (denoted as "L"), it becomes a communication buffer between the camera and the lens.

The microcomputer PR5 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 outputted as the signal SI, and the microcomputer PR5 inputs the signal Sl as lens data in synchronization with 5CLK.

DDR is a switch detection and display circuit, and the signal CD
Selected when DR is "H", So, Sl.

Controlled by microcomputer PR5 using 5CLK. In other words, the display of the camera's display member DSP can be switched based on data sent from the microcomputer PR3, and the on/off status of various operating members of the camera can be controlled by the microcomputer P by communication.
Notify R5.

The automatic focus adjustment (AF) mode of the camera is set by the microcomputer PR3 recognizing the state of the switch group SWS via the switch detection circuit DDR. That is,
When a specific switch in the SWS is ON, 0NE
SHOT mode (locks focus once focused), O
When using FF, it is possible to set the 5ERVO mode (focus adjustment is performed regardless of whether the lens is in focus or out of focus).

SWI and SW2 are switches that are linked to a release button (not shown), and when the release button is pressed in the first step, SW is activated.
I is turned on, and then SW2 is turned on at the second stage of depression. The microcomputer PR3 performs SWI on/off light control and automatic focus adjustment, and the SW2 on/off control performs exposure control and subsequent film winding.

Note that the switch SW2 is connected to the "interrupt input terminal" of the microcomputer PR5, and even if a program is being executed when SW1 is on, an interrupt is generated by turning SW2 on and off, 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 spring charging, and forward and reverse rotation is controlled by respective drive circuits MDRI and MDR2. Microcomputer PR5 to MDRI, MDR2
Signals MIF and MIR input to the.

M 2 F and M 2 R are signals for motor control.

MG1 and MG2 are magnets for starting the movement of the front and rear shutter curtains, respectively, and the signals SMGI, 5MG2.
The amplification transistors TRI and TR2 are energized, and the microcomputer PRS performs shutter control.

Note that the switch detection and display circuit DDR, motor drive circuits MDR1 and MDR2, and shutter control are not directly related to the present invention, so detailed explanations thereof will be omitted.

LPR5 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 LPR5 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.

This embodiment shows an example of a zoom lens, and when a focus adjustment command is sent from a camera, the focus adjustment motor LTMR is activated according to the driving amount and direction sent at the same time.
is driven by signals LMF and LMR to move the focusing optical system in the optical axis direction to perform focus adjustment. The amount of movement of the optical system is determined by a pulse signal 5EN of an encoder circuit ENCF that detects the pattern of a pulse plate that rotates in conjunction with the optical system using a photocoupler and outputs a number of pulses according to the amount of movement.
Monitored by CF, counted by counter in circuit LPR3,
When the count value matches the movement amount sent to the circuit LPR3, PR3 itself sets the signals LMF and LMR to "L".
to control motor LMTR.

Therefore, once the focus adjustment command is sent from the camera, the microcomputer PR5, which is the camera control device, does not need to be involved in lens driving at all until the lens driving is completed. Furthermore, the configuration is such that it is possible to send the contents of the counter to the camera if there is a request from the camera.

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

ENCZ is an encoder circuit attached to the zoom optical system, and circuit LPR8 inputs signal 5ENCZ from encoder circuit ENCZ to detect the zoom position. Lens parameters at each zoom position are stored in the control circuit LPR5, and upon a request from the camera-side microcomputer PR8, parameters corresponding to the current zoom position are sent to the camera.

The 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 the microcomputer PR3, and is used for automatic exposure control according to a predetermined A/D conversion program. used.

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 PR3 using o, Sl, and 5CLK.

Signal φ5 given from drive circuit SDR to sensor device SNS
ELO, φ5ELI is the signal 5EL from the microcomputer PR5
O,5ELI itself, φ5ELO="L", φ5
When ELL-“L”, sensor row pair 5NS-1 (SNS-
1a, 5NS-1b), φ5ELO-″H”, φS
When EL, 1=“L”, sensor row pair 5NS-4 (SNS
-4a.

5NS-4b), φ5ELO="L", φS E L
1-When “H”, sensor row pair 5NS-2 (SNS-2
a, 5NS2b), φ5ELO="H", φ5ELI
= “H”, sensor row pair 5NS-3 (SNS-3a
, 5NS-3b).

After the accumulation is completed, set 5ELO and 5ELI appropriately,
By sending the clock φSH1φHR3, 5ELO
, 5ELI (φ5ELO, 5ELL) are sequentially and serially outputted from the output VOUT.

VPI, VF6. VF3. VF6 has each sensor row pair 5NS-1 (SNS-1a, 5NS-1b), 5N
S-2 (SNS-2a, 5NS-2b), 5NS-3
(SNS-3a.

5NS-3b), 5NS-4 (SNS-4a, 5NS-
4b) is placed near the subject brightness monitor sensor (
(not shown) whose voltage increases as the accumulation starts, and the accumulation control of each sensor row is performed by 9.

Shinji φRES, φVR3 are sensor reset clocks, φHR8, φSH are image signal readout clocks,
φTl, φT2. φT3. φT4 is a clock for ending the accumulation of each pair of sensors JIJ.

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 dark current output is the output value of the light-shielded pixels in the sensor array, and SvR is the microcomputer PR5.
The output is held in a capacitor by the signal DSH from the image signal, and differential amplification is performed between this and the image signal. Output VIDEO
is input to the analog input terminal of the microcomputer PR5, and the microcomputer PR5 sequentially stores the digital value of the signal from the A/D conversion station into a predetermined address on the RAM.

Signals /TINTEI, /TINTE2. /TINTE3
゜/TINTE4 is the sensor row pair 5M5-1 (
SNS-1a, 5NS-1b), 5M5-2 (SMS
-2a, 5NS2b), 5NS-3 (SNS-3a,
5NS-3b), 5NS4 (SNS-4a,
The microcomputer PR5 receives this signal and executes reading of the image signal.

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

CKI, CR2 are the above clocks φRES, φVR3
To generate ゜φ)(RS, φSH, the microcomputer P
This is a reference clock given from R5 to the sensor drive circuit SDR.

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

Thereby, photoelectric conversion of the subject image formed on each sensor is performed by the four sensor row pairs, and charges are accumulated in the photoelectric conversion element portion of the sensor. At the same time, the signals VPI to VP4 of the brightness monitoring sensor of each sensor rise, and when this voltage reaches a predetermined level, the sensor drive circuit SDR sets the signals /TINTEI to /TINTE4 to "L" independently.

The microcomputer PR8 receives this and outputs a predetermined waveform to the clock CK2. The sensor drive circuit SDR generates clocks φSH and φHR8 based on CR2 and drives the sensor device S.
NS, the sensor device SNS outputs an image signal based on the clock, and the microcomputer PR3 uses its internal A/D conversion function to convert the output VIDEO input to the analog input terminal in synchronization with the CR2 output by itself. After A/D conversion,
The signals are sequentially stored as digital signals at predetermined addresses in the RAM.

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 rows, so they will not be described here. Detailed 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.

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

FIG. 4(a) is a very rough flowchart of the entire sequence of the camera.

When power supply starts to the circuit shown in Fig. 2, the microcomputer P
R3 starts execution from step (101) in FIG. 4(a). In step (102), the state of the switch SWI, which is turned on by pressing the release button in the first step, is detected, and if it is off, the process moves to step (103), where fluctuations and flag types are initialized. If the switch SWI is on, the process moves to step (104) and the camera starts operating.

In step (104,), a ``rAE control'' subroutine for photometry, detection of various switch states, display, etc. is executed.

Since the AE control is not directly related to the present invention, detailed explanation will be omitted. When the "subroutine rAE control" is completed, the process then moves to step (105).

In step (105), the "rAF control" subroutine is executed. Here, sensor accumulation, focus detection calculations, and automatic focus adjustment operations using lens drive are performed. When the "subroutine rAF control" is completed, the process returns to step (102) and steps (104) and (105) are repeatedly executed until the power is turned off.

Note that the flowchart of this embodiment does not describe the release operation, but since the release operation is not directly related to the present invention, it is intentionally omitted.

FIG. 4(b) is a flowchart of the "subroutine rAF control" executed in step (105).

When "subroutine rAF control" is called, AF control from step (202) onwards is executed through step (201).

In step (202), AF mode is ON
Determine whether it is OT mode or 5ERVO mode, 0N
In the case of ESHOT, the process moves to step (203).

In step (203), it is determined whether or not the previous focus detection result was in focus, and if it was in focus, no new focus adjustment operation is performed (in step (204), subroutine rAF control) is performed. to return.

If focus is not determined in step (203),
If the AF mode is the 5ERVO mode in step (202), the process moves to step (205) to perform a new focus adjustment operation.

In step (205), a subroutine "focus detection" is executed to detect the focus of a plurality of subject areas and detect the defocus amount of each area. This specific method is described in detail in Japanese Patent Application No. 1-291130, which was previously proposed by the present applicant, and therefore will not be described in the present invention.

The defocus amount is detected for each of the four subject areas in the embodiment of the present invention, and the defocus amount DE is detected for each area.
FI, DEF2. DEF3. It is assumed that DEF4 is obtained. It is also assumed that for each area, it is determined whether focus detection is possible or not based on the contrast of the image signal or the like using a known method.

In the next step (206), a subroutine "judgment l" is executed. "Judgment l" is the focus detection system (optical system and sensor)
This is a subroutine to eliminate false detection results caused by dirt present in the sensor.

A flowchart of "determination 1" is shown in FIG. 4(c).

When the “judgment l” subroutine is called,
), the process proceeds to step (302).

Step (302) represents a loop process in which processing is performed for each of the four subject areas of this embodiment, and the process is performed while changing the argument i representing the area from 1 to 4.

First, set argument 1 to 1 and proceed to step (303).

In step (303), the sensor 5NS-i, that is, SN
! It is determined whether focus detection of the first subject area handled by ll+-1 was possible, and if possible, step (
304). If it is not possible, end the loop when i is 1, set 2 to ] and step again (
303) onwards.

If focus detection is possible and the process moves to step (304), DEFi, that is, defocus 1D of the first subject area.
It is determined whether EF1 is within a predetermined defocus range DEFA to DEFB. Said DEFA.

DEFB is a value determined by the configuration of the focus detection system (optical system, sensor), and if dust adheres to the focus detection optical system and the sensor detects the image of the dust, it will be detected as a roughly constant amount of defocus. The principle is that Therefore, the detection defocusing method is I) E F A
-D E F When it is between 8, it means that there is a possibility that the defocus amount is a false defocus amount due to dust.

Here, the flags used in the processing loop (302) will be explained.

PH51i flag: Detects defocus amount within the DEFA-DEFB range once in subject area i.

PH52i flag: Defocus amount within the DEFA to DEFB range was detected twice in the subject area l. It is assumed that the amount of false defocus is due to dust, and the area i is treated as undetectable.

PH33i flag The defocus amount within the range of DEFA to DEFB was detected twice in the subject area i, and the first time was treated as undetectable, but after that, the amount of defocus outside the DEFA-DEFB range was detected, so from now on, the amount of defocus within the range of DEFA to DEFB was detected Even if a defocus amount within the DEFB range is detected, it is not treated as undetectable.

Now, if the detected defocus amount DEFI of the subject area 1 is within the DEFA-DEFB range in step (304), the process proceeds to step (309).

Step (309) Te is 7-7g PH51i, i.e. P
The H8II flag is determined, and if it is already set, the process moves to step (313).

In step (313), since defocus within the DEFA-DEFB range was detected twice, the PH8IN flag is cleared, the PH321 flag is set, and in the next step (314), the sensor 5M5-i, that is, the object area 1
The loop processing for area l is ended by treating the area as undetectable.

If the PHS l 1 flag is raised in step (309), the process moves to step (310) and the flag PH
52i is determined.

At step (310), the flag PH32i, that is, PH5
If the 21 flag is set, step (314)
The subject area 1 is treated as being unable to detect focus.

If the P H521 flag is clear, step (31
The process moves to 1) and the flag PH53i is determined.

In step (311), the flag PH53i, that is, P
If the H531 flag is set, the process branches to terminate the loop process of step (302) for object area 1, since it is not treated as undetectable as described above.

If the PH531 flag is cleared in step (311), it is assumed that the detected defocus amount of area 1 is within the DEFA-DEFB range for the first time, and the process moves to step (312), where the PH5II flag is set. End loop processing.

Now, returning to step (304), if the detected defocus of the subject area l is not within the range DEFA-DEFB, the process moves to step (305).

In step (305), the flag PH31i, that is, PH3
If the II flag is determined and set, step (
At step 308), the PH8II flag is cleared and the loop processing of area 1 is ended.

If the PH3II flag is cleared in step (305), then in step (306) the flag PH82i is cleared.
.

That is, the PH321 flag is determined, and if it is clear, the loop processing of area 1 is ended. If it is not clear, as mentioned above, the detected defocus amount in area 1 will be DE
In order not to make detection impossible even if it falls within the range of FA-DEFB, the process moves to step (307), where the PH521 flag is cleared and the PH531 flag is set, and then the loop processing for area l is ended.

After the loop processing of area 1 is completed, step (3) is performed again.
Return to the beginning of 02), set the argument i to 2, and set the object area 2.
A similar loop process is executed for.

After the processing for area 2 is completed, similar processing is performed for area 3.4.

When all the loop processing for the subject areas 1 to 4 is completed, the process moves to step (315) and returns to the subroutine "determination 1".

To summarize the operation of the above "Judgment l" subroutine, for each subject area, it is judged whether the detected defocus amount is within a predetermined defocus range, and if it is within a predetermined defocus range, if it is detected twice, there is dust in the focus detection system. This area is recognized as a false defocus, and focus detection is disabled in that area, and if the detected defocus falls outside the predetermined defocus range after entering the area twice, it cannot be detected even if the detected defocus falls within the range. It is not to be treated as such.

Returning to FIG. 4(b), the explanation of the flowchart will be continued.

When the execution of the "Judgment 1" subroutine is completed in step (206), the subroutine "1 Judgment 2" is executed in the next step (207).

The "Judgment 2" subroutine is used in an automatic focus adjustment device that adjusts the focus of a photographic lens based on the focus detection results of multiple subject areas. This is a subroutine to prevent the lens drive from falling into an oscillation state.

The flowchart of the “Judgment 2” subroutine is shown in Figure 4 (d
) Shown in (e).

When the "Judgment 2" subroutine is called, Fig. 4(d)
After step (401), the process from step (402) onwards is executed.

In step (402), subroutine rJDGSJ is executed.

The subroutine "JDGS" is a subroutine that, when a certain subject area once becomes detectable and then becomes undetectable, is treated as undetectable unless the release button is released even if the area becomes detectable again.

"When the JDGsJ subroutine is called,
The loop process of step (502) is executed through step (501) of e).

Step (502), similar to step (302) described above, represents a loop process in which processing is performed for each of the four subject areas of this embodiment, and the process is performed while changing the argument i representing the area from 1 to 4. I'm going to go.

First, the argument i is set to 1 and step (503) is executed.

In step (503), sensor SNS-i.

That is, it is determined whether or not focus detection is possible for the subject area in charge of 5NE-1, and if possible, the process moves to step (506).

Here, the flags used in the loop processing of step (502) will be explained.

ENOi: The focus of the subject area i is now detectable.

DISi The subject area i was once able to detect its focus, but then became undetectable. Thereafter, even if focus becomes detectable again, it is treated as undetectable.

In other words, - if a focus point that was previously detectable becomes undetectable, it is treated as impossible even if focus becomes detectable again, and the selection area is switched when the photographing lens is driven, and the lens This prevents the drive from going into an oscillating state.

Now, in step (506), the flag DIS has already been set.
i, here i is set to l, so if the DIS 1 flag is set, the process moves to step (508), and as described above, object area 1 handled by 5M5-1 is treated as undetectable. , the loop processing for area l ends.

If the DISI flag is clear in step (506), the process moves to step (507), where the ENOI flag is set, assuming that the subject area l has become focus detectable. Then, the loop processing for area l ends.

If it is not possible to detect the focus of the subject area 1 handled by the sensor 5NS-1 in step (503), step (504) is performed.
Move to.

If the flag ENOi, that is, the ENOl flag is set in step (504), the process moves to step (505), in which the Dis 1 flag is set, assuming that object area 1 has become undetectable after being detectable as described above. The loop processing for object area 1 ends.

If the ENOI flag is still clear in step (504), the loop processing of area 1 is ended without executing anything.

When the loop processing for the subject area l is completed, the argument i representing the area is set to 2. 3. 4, the loop processing is executed in the same way.

When the loop processing is completed for all subject areas, the process moves to step (509) and the subroutine rJDGsJ
to return.

When the subroutine rJDGsJ ends, the process shown in FIG. 4(d)
The process returns to the next step (403).

In step (403), it is determined whether or not all sensors (regions) are unable to detect focus based on the execution result of the subroutine rJDGsJ executed in the previous step (402), and if all sensors are unable to detect focus, step After moving to (404) and clearing all flags ENOi and DISi,
At step (405), subroutine ru:+cs
”. This is possible if all areas become undetectable due to the execution of the subroutine rJDGsJ executed in step (402), if all areas are truly undetectable by the current focus detection operation, and if all areas are truly undetectable by the current focus detection operation. This is because even if there is a possible area, it may be treated as unfocusable due to the action of the flag DISi. In the first place, the purpose of subroutine l'-JDGSJ is to suppress unnecessary oscillation of the photographing lens caused by switching the selected subject area depending on whether focus detection is possible or not.
Even though there is a focus detectable subject area, making all areas undetectable is an operation that is different from the original purpose.Therefore, in step (404), a flag is set to make the subroutine rJDGSJ function. After clearing all once, rJDG again in step (405)
This causes sJ to be executed.

In step (403), if all subject areas are not focus detectable, or after subroutine rJDGsJ in step (405) is executed, the process moves to step (406) and returns to subroutine "Determination 2".

Subroutine [When the execution of judgment 2J is finished, the process shown in Fig. 4 (
The process moves to step (208) in the flowchart of b).

The explanation will be continued based on the flowchart of FIG. 4(b) again.

In step (208), it is determined whether or not all sensors, that is, all subject areas, are unable to detect focus. If all sensors are unable to detect focus, the process moves to step (214), and the subroutine "search lens drive" is performed. 1. This is a control that executes the focus detection operation while driving the photographing lens when the contrast of the subject is low and the focus cannot be detected. Since the present invention has already been disclosed, a detailed description of the present invention will be omitted.

If it is determined in step (208) that the focus cannot be detected in all subject areas, the process moves to step (209) and a subroutine "sensor selection" is executed.

The subroutine "sensor selection" is a subroutine for selecting a subject area for final focus adjustment from among a plurality of subject areas (sensors) whose focus can be detected, and the flowchart is shown in FIG. 4(f). It shows.

When the subroutine "sensor selection" is called, the process goes through step (601) in FIG. 4(f) and then goes to step (602).
) The following processing is executed.

First, in step (602), -30 (mm) is stored as an initial value in the variable DEF representing the final defocus amount. In the embodiment of the present invention, a positive defocus amount means rear focus, and a negative defocus amount means front focus. Therefore, the initial value -30 (mm) represents a very large front focus defocus amount. ing.

In the next step (603), the automatic focus adjustment (A
F) Determine the mode, if the mode is 5ERVO, go to step (607); if the mode is 0NESHOT, go to step (60)
Move on to 4). It is assumed that the AF mode has been set in advance according to the state of the operating members of the camera in the "subroutine rAE control" of step (104) in FIG. 4(a).

The case where the AF mode is 0NESHOT mode will be explained.

Step (604) represents a loop process in which processing is performed for each of the four subject areas (sensors) of this embodiment, and the process is performed while changing the argument 1 representing the area (sensor) from 1 to 4.

First, 1 is set in \I], and the process proceeds to step (605).

In step (605), a subroutine [defocus update-] is executed.

The subroutine "defocus update" updates the defocus amount of the focus detectable area and the final defocus it D
This is a subroutine for comparing E F and setting the larger defocus amount as the final defocus amount.

FIG. 4(g) shows a flowchart of the subroutine [Defocus Update-1].

When the subroutine "Defocus Update" is called,
After step (701) in FIG. 4(g), step (
702) The subsequent processes are executed.

In step (702), 5NS-i, that is, the argument l
Since l is set in , it is determined whether or not focus detection is possible for object area 1, which is 5NS-1, and if it is not possible, nothing is executed and the process moves to step 1). , perform one turn of the subroutine "defocus update".

[IT p, If yes, move to step (703) and compare the defocus amount DEF1 of area 1 with the final defocus amount DEF, and if DEF is larger, do nothing and skip step At (705), the subroutine is returned. If DEFI is larger, step (70
Move on to 4).

In step (704), the defocus amount DEF of area 1 is
I is stored in the final defocus amount DEF, and in the next step (705), the subroutine "defocus update" is returned.

When the subroutine ``defocus update J'' returns,
Returning to FIG. 4(f), in the loop process of step (604), the argument i representing the subject area is changed to 2, and the subroutine "defocus update" of step (605) is similarly executed. Similar processing is performed with the argument i set to 34.

When the loop processing of step (604) is completed for all subject areas, the process moves to step (606) and returns to the subroutine "sensor selection".

In the 0NESHOT mode, in step (604), the largest defocus amount among the focus detectable subject areas is set as the final defocus amount. As mentioned above, in this embodiment, when the defocus amount is a positive value, it represents the rear bin, so the final defocus amount is the defocus amount of the rearmost bin.

The rearmost bin means that the subject area that shows the amount of defocus is located closest to the camera, and in the end, in ON E S HOT mode, the focus is on the closest subject. Adjustments will be made.

7. Chip (603) fate AF mode is 5ER
Step (607) if set to VO mode
Move to.

In step (607), 5NS-1 or 5NS4
That is, as explained in FIG. 3, it is determined whether focus detection is possible for either object area 1 or 4 located at the center of the screen, and if possible, the process proceeds to step (613); if not, the process proceeds to step (613). The process moves to step (608).

If either the subject area l or 4 located at the center of the screen can be focused, the argument i representing the area is set to 1 in step (613), and the subroutine ``defocus update'' is executed in the next step (614). Execute. Next, in step (615), the argument i is set to 4, and in the next step (616), the subroutine "defocus update" is executed.
Execute. Then, in step (617), the subroutine "sensor selection" is returned.

By executing steps (613) to (616), the defocus amount of the larger one of the subject areas 1 and 4 will be stored as the final defocus amount DEF. Of course, if either one of them is unable to detect focus, it is clear that the possible defocus amount is stored.

If it is determined in step (607) that the focus cannot be detected in both subject areas 1 and 4, steps (608) and subsequent steps are executed.

In step (608), the argument i representing the subject area is set to 2.
is set, and the subroutine "defocus update" is executed in the next step (609).

Next, in step (610), the argument i is set to 3, and in the next step (611), the subroutine "defocus update" is executed again. Then, in step (612), the subroutine "sensor selection" is returned.

Areas 2 and 3 set in step (608) or (610) represent the subject area around the screen, as shown in FIG.

As described above, in the case of the 5ERVO mode, if the subject area located at the center of the screen can be focus-detected, the defocus amount of that area is set as the final defocus 1. In the case of this embodiment, there are two subject areas, areas 1 and 4, in the center of the screen, so if focus detection is possible in both areas, the closest area is selected.

When the subroutine "sensor selection" is returned, the process returns to FIG. 4(b) and proceeds to step (210).

In step (210), it is determined whether the photographic lens is in focus based on the finally obtained defocus amount. If it is in focus, the process moves to step (213), executes the subroutine "in-focus display", displays the focus in the viewfinder, and in the next step (215) returns the subroutine [AF control go]. .

If it is determined in step (210) that the lens is not in focus, the process proceeds to step (211) to drive the lens, and then in step (215) the subroutine rAF control is returned. The lens drive is disclosed in Japanese Patent Application No. Sho 61-160824 filed by the present applicant and the like, so a detailed explanation will be omitted.

In the embodiment described above, the target operation is performed by remembering whether or not focus detection is possible only once, but in order to obtain stable operation, each or either one of them is set to multiple times. It is clear that the objective operation of the present invention can be achieved even if it is determined based on time or time.

Another method for obtaining stable operation is to ensure that the final defocus amount is within a predetermined value and that the
It may also be possible to start a storage operation that is disabled.

〔Effect of the invention〕

In the present invention, past enablement/disability of focus detection is stored for each of a plurality of subject areas, and - after star detection becomes possible,
When that area becomes undetectable, it is forcibly treated as undetectable even if the area becomes focus detectable again, so malfunctions in the drive of the photographing lens caused by repeating focus detectable and undetectable. It becomes possible to suppress the

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a flow chart for explaining the main operations of the present invention, FIG. 3 is a configuration diagram showing the detailed configuration of the focus detection system in the camera shown in FIG. be. SNS...Sensor PH1...Microcomputer CNS...Lens 130/)

Claims (3)

[Claims] (1) Defocus amount detection means for repeatedly detecting the amount of defocus of a plurality of subject areas within the screen of the photographic lens, and whether or not it is possible to detect the amount of defocus of the plurality of subject areas based on the results of the detection means. a determination means for determining whether or not the object is in focus for each region; and a determination means for determining, for each region, based on the result of the determination means, it is stored for each region that it was possible to detect the amount of defocus in the plurality of subject regions at least once in the past. a memory means to
An automatic focus adjustment device comprising means for selecting at least one region from among the plurality of subject regions based on the results of the defocus amount detection means, determination means, and storage means. (2) The automatic focus adjustment device according to claim 1, wherein the selection means changes the area to be selected as a candidate based on the results of the determination means and storage means. (3) a defocus amount detection means for repeatedly detecting the defocus amount of a plurality of subject areas within the screen of the photographic lens; and a determination means for determining whether or not the defocus amount detected by the detection means is appropriate for each area; Disabled area holding means for holding an area in which the amount of defocus once detected by the determining means is determined to be inappropriate as an disabled area regardless of a subsequent determination result of the determining means; It is characterized by having a selection means for selecting a predetermined region from the amount of defocus in other regions other than the region, and a lens driving means for driving the lens based on the amount of defocus in the region selected by the selection means. Automatic focus adjustment device.