JPS63172229A - Auto-focusing device - Google Patents

Abstract

PURPOSE:To improve the operability of the titled device especially at the time of mounting a telephoto lens by driving a lens immediately when a defocused value after the detection of a focus is < a prescribed value, and when the defocused value is >= the prescribed value, inhibiting the lens driving. CONSTITUTION:When a focus detecting result based upon a sensor device SNS reaches a focus or close to the focus, a microcomputer PRS immediately drives the lens LNS when the defocused value is within the prescribed value, and if the value exceeds the prescribed value, inhibits the lens driving for the 1st prescribed time from the focusing point or a point of time close to the focusing point. When an object is searched at a low contrast, the searching operation is inhibited during the 2nd prescribed time longer than the 1st prescribed time. Consequently, focusing improved at its operability especially at the time of mounting the telephoto lens can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a focus adjustment device for a camera or the like.

[Conventional technology]

Conventionally, as one type of camera focus adjustment device, the exit pupil of the photographic lens is divided into two by a focus detection optical system, and the two subject images formed by the light flux passing through each pupil area are converted into photoelectric converters. Receives light with an element array (for example, a CCD sensor array), detects the focal state of the photographing lens from its output,
A method is known in which a photographic lens is driven based on the detection result.

In the focus detection operation described above, if the contrast of the subject image is sufficient, highly accurate focus detection is possible, but if the contrast is low, focus detection becomes impossible. A so-called "search operation" is often performed in which the photographic lens is driven independently in the hope that the contrast of the subject will increase.

This is because the contrast may be low because the contrast of the subject is essentially low, or because the amount of defocus of the photographic lens is large, resulting in low contrast.

However, the above search operation normally involves driving the photographing lens one round trip from the closest end to the infinity end on the distance ring.
When a telephoto lens is attached, and the subject moves away from the so-called distance measurement frame in the viewfinder due to camera shake, etc., the contrast becomes low and a search operation is performed immediately, making it difficult to refocus on the subject after a round trip. The inconvenience was that it took a long time to do so.

〔the purpose〕

The present invention aims to solve the above-mentioned problems, and its gist is that when the focus detection result becomes in focus or near focus, if the subsequent defocus amount is within a predetermined amount, the lens is immediately driven and In the above cases, lens driving is prohibited within a first predetermined time period from the time when the subject is in focus or near focus, and when the subject performs a search operation with low contrast, the lens drive is prohibited for a period longer than the first predetermined time period. By prohibiting the search operation during the second predetermined time period, it is possible to perform focus adjustment with improved operability, especially when a telephoto lens is attached.

〔Example〕

First, the principle of focus detection in the present invention will be explained using FIG. A field lens FLD is placed along the same optical axis as the photographing lens LNS whose focus is to be detected. Behind it, two secondary imaging lenses FCLA and FCLB are arranged at symmetrical positions with respect to the optical axis. Furthermore, sensor arrays SAA and SAB are arranged behind it. Apertures DIA and DT are located near the secondary imaging lenses FCLA and FCLB.
B is provided. The field lens FLD forms two secondary images of the exit pupil of the photographic lens LNS, FCLA and FC.
The image is almost formed on the pupil plane of LB. As a result, the ray bundles incident on the secondary imaging lenses FCLA and FCLB are arranged on the exit pupil plane of the photographic lens LNS with equal areas that do not overlap with each other and correspond to the secondary imaging lenses FCLA and FCLB. It will be ejected from the area. The aerial image formed near the field lens FLD is sent to sensor arrays SAA and SAB by secondary imaging lenses FCLA and FCLB.
When the image is re-formed on the plane of the image, the positions of the two images on the sensor arrays SAA and SAB are considered based on the displacement of the aerial image position in the optical axis direction. Therefore, if the amount of displacement (shift) in the relative positions of the two images on the sensor array is detected, the photographing lens LNS
The focal state of the object can be known.

FIG. 2 shows an example of photoelectric conversion outputs of two images formed on the sensor arrays SAA and SAB. The output of SAA is A (i),
Let the output of SAB be B (i). In this example, the number of pixels of the sensor is 40 (i=o, . . . , 39).

A signal processing method for detecting image shift iPR from image signals A (i) and B (i) is disclosed in Japanese Patent Application Laid-Open No. 58-14230.
6, JP-A-59-107313, JP-A-6
Publication No. 0-101513 or patent application No. 1983-160
No. 824 is disclosed by the applicant.

By adjusting the focus of the photographic lens based on the amount of image shift obtained by the methods disclosed in these publications, it is possible to bring the photographic lens into focus.

FIG. 3 is a circuit diagram showing an embodiment of a camera equipped with an automatic focusing device according to the present invention.

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

EEFROM (Electrically Erasable Programmable RO)
M) is an l-chip microcomputer with an A/D conversion function, which performs camera functions such as automatic exposure control function, automatic focus detection function, and film winding/rewinding according to the camera sequence program stored in ROM. is performing an action. EEPROM is a type of non-volatile memory.
Various adjustment data are written in the process.

PH1 is communication signal SO, Sr, SCL
K is used to communicate with peripheral circuits and lenses, and to control the operation of each circuit and lens.

SO is the data signal output from PH1, sr is PH1
The data signal input to SCLK is the signal So,
This is the synchronization signal of Sl.

LCM is a lens communication buffer circuit, and when the camera is in operation, it supplies the lens power supply VL to the lens, and the PH1
When the signal CL from CM is at a high potential level, it serves as a buffer for communication between the camera and the lens.

When PH1 sets CLCM to Ize and sends predetermined data from SO in synchronization with SCLK, LCM sends buffered signals LCK and DCL of 5CLK and So to the lens through the camera-lens interface. Output.

At the same time, a buffer signal of the signal DLC from the lens is output to SI, and PH1 inputs lens data from SI in synchronization with 5CLK.

SDR is a drive circuit for the line sensor device SNS for focus detection, and is selected when the signal C3DR is H'.
Controlled from PH1 using O, S I and S CL K.

The signal CK is the CCD driving clock φ1. A clock is provided for generating φ2, and a signal INTEND is a signal that notifies PH1 that the accumulation operation has ended.

The output signal O8 of the SNS is the clock φ1. It is a time-series image signal synchronized with φ2, and after being amplified by an amplifier circuit in the SDR, it is output to PH1 as AO3. PH1 is AO
3 is input from the analog input terminal, and in synchronization with CK, the data is A/D converted by the internal A/D conversion function and sequentially stored at a predetermined address in the RAM.

AGC, which is the output signal of the SNS, is the output of the AGC control sensor in the SNS, and is input to the SDR and used for storage control of the SNS.A series of operations of the SDR will be described in detail later.

SPC is a photometric sensor for exposure control that receives light through the photographic lens, and its output 5spc is input to the analog input terminal of PH1, and after A/D conversion, it is used for automatic exposure control (
AE).

DDR is a switch sense and display circuit, which is selected when the signal CDDR is H', and the SO.

Controlled from PH1 using Sl and 5CLK. That is,
Based on the data sent from PH1, the display of the camera's display member DSP can be switched, and the on/off state of various operation members such as the release button (not shown) (linked to switches SWI and SW2) and mode setting buttons can be controlled by PH1. Contact.

MDRI and MDR2 are drive circuits for film feeding and shutter spring winding motors MTRI and MTR2, and signals MIF, MIR, M2F, and M2R are used to control the normal rotation and
Perform a reversal.

MCI and MG2 are magnets for starting the movement of the shutter front curtain and rear curtain, respectively, and the signals SMGI, 5MG2. The amplification transistors TRI and TR2 are energized, and the shutter control is performed by PH1.

In addition, switch sense and display circuit DDR.

Since the motor drive circuits MDRI, MDR2, and shack control are not directly related to the present invention, detailed explanations thereof will be omitted.

A signal DCL input to the intra-lens control circuit LPR8 in synchronization with LCK is data of a command from the camera to the lens FLNS, and the operation of the lens in response to the command is determined in advance.

L P RS analyzes the command according to a predetermined procedure, and performs focus adjustment and aperture control operations, as well as various lens parameters from the output DLC (open F number, focal length, defocus amount vs. extension amount coefficient, etc.) Outputs.

In the embodiment, an example of a single lens that is fully extended is shown, and when a focus adjustment command is sent from the camera, the focus adjustment motor L M T R is activated according to the drive amount and direction sent at the same time. Signal LMF.

Driven by LMR, the optical system is moved in the optical axis direction to adjust focus. The amount of movement of the optical system is determined by the encoder circuit EN.
Monitor with C pulse signal 5ENC, L P RS
When the specified movement is completed, the signals LMF and LMR are set to L' and the motor LMT is
Brake R to S.

When an aperture control command is sent from the camera, a stepping motor DMTR, which is known for driving an aperture, is driven according to the number of aperture stages sent at the same time.
Stepping motors can be controlled open, so
Does not require an encoder to monitor operation.

The operation of the camera with the above configuration will be explained according to the flow shown in FIG. 4.

When a power switch (not shown) is operated, power supply to the microcomputer PR3 is started, and PR8 starts executing the sequence program stored in the ROM.

FIG. 4(a) is a flow chart showing the overall flow of the above program. When execution of the program is started by the above operation, the state of the switch SWI, which is turned on at the first stroke of the release button, is detected in step (002), and when the switch SWI is off, in step (003), A drive stop instruction is issued by sending a "drive stop command" to the lens. In the next step (004), all control flags set in the RAM in PR8 are cleared. Above steps (002), (003), (004) switch S
This process is repeated until WI is turned on or the power switch is turned off. Therefore, even if the lens is being driven, when SWI is turned off, the lens will stop driving. By turning on SWI, step (0
05). Step (005) is rAE control.”
This means a subroutine. In this "rAE control" subroutine, a series of camera operation controls such as photometric calculation processing, exposure control, post-exposure shutter charge, and film winding are performed.

Note that the [AE control] subroutine is not directly related to the present invention, so a detailed explanation will be omitted, but an outline of the function of this subroutine is as follows.

While the SWI is on, this "l'-AE control" subroutine is executed, and each time the photometry and exposure control calculation 1 display is performed. When the switch SW2 is turned on by the second stroke of the release button (not shown), the microcomputer P
The release operation is started by the interrupt processing function of R3, and the aperture or shutter speed is controlled based on the exposure 1 determined by the exposure control calculation described above, and after the exposure is completed, the shutter charge and film feeding operations are performed. This completes the shooting of one frame of film.

Note that the camera according to the embodiment of the present invention has two modes as the AP mote: so-called "one-shot" and "servo" modes. When the AF mode is one shot,
Once the camera is in focus, the focus adjustment operation will not be performed again until the switch SW is turned off, and the shutter cannot be released until the camera is in focus.

In the servo mode, focus adjustment continues even after focusing, and release is possible at any time regardless of the focus detection result. Therefore, the above-mentioned interrupt processing is permitted when focus is achieved in the case of one-shot, and is permitted in the case of servo, but it is once prohibited after the release operation, and the next step (006) is the rAF control subroutine. Allowed again after execution. Selection of one-shot servo is made by a mode selection switch (not shown).

As mentioned earlier, the release operation is performed by turning on the switch SW2, but even if SW2 is left on even after one frame of film has been shot, the rAE control returns as having been terminated. .

Therefore, to explain the operation with SW2 turned on,
In the case of a one-shot, the release will not be released until the focus is achieved, and once the focus is achieved, the release will be enabled and one frame will be taken. After that, since it is a one-shot, no focus adjustment will be performed, and the next frame will be taken while the lens remains in the same position. Photographing is performed, and photographing continues as long as the switch SW2 is on.

In the case of a servo, the release is possible, so SW2
Shooting begins immediately when is turned on. Then, after one parfocal adjustment is performed in the "rAF control" routine, the release is enabled again and shooting is performed, and in the end, while SW2 is on, "Release operation JrAF control" and "Release operation" are performed.
"AF control" will be repeated alternately. This situation is called ``AF continuous shooting,'' and in order to recognize this situation in the ``rAF control'' routine, which will be described later, a flag called RLS is set to 1 after the release operation in the ``rAE control'' subroutine. Te(.

Now, as mentioned above, when the "AE control" subroutine ends in step (005), step (005)
06) rAF control subroutine is executed.

FIG. 4(b) shows a flowchart of the "AF control" subroutine. First, in step (102), the AF mode state is detected. This is switch sense circuit D
This is done by knowing the state of an AF mode setting switch (not shown) by communicating with the DR.

If the AF mode is one shot, step (], 03
) to detect the state of flag JF. As will be described later, JF is a flag indicating the focus state that is set in the "judgment" subroutine of step (130), and checking flag JF in step (103) means checking the previous focus state. means. Here flag J
If F is 1, it was in focus last time, so step (104)
Then, the rAF control subroutine is returned. That is, in the one-shot I mode, once the focus is achieved, the switch SWI is turned off and new AF control is not performed until all flags are cleared in step (OO4). During the first rAF control after turning on the switch SWI, the flag JP is naturally cleared, so the process moves to step (108).

If it is the servo mode in step (102), the process moves to step (105).

In step (105), the state of the flag RLS is detected. RLS is set in the "rAE Control" subroutine as described above. This flag is set to 1 after the release operation. If the flag RLS is set in step (105), it is recognized that it is immediately after release in servo mode, that is, rAF continuous shooting, and the process moves to step (106).

If it is "JAF quick copy", all flags are first cleared in step (106), then flag FAF is set to 1 in step (107), and then the process moves to step (129). Since release is possible even in servo mode, it is possible that interrupt processing will transition to the release operation routine at any step in the program, and in that case, the process that was being executed immediately before branching to the release interrupt Step (1) to avoid being affected
06), all flags are cleared. FAF
is a flag for recognizing "quick shooting AFJ" in the "AF control" subroutine.

If the flag RLS is O in step (105), the process moves to step (108).

In step (1,08), the state of the flag PRMV is determined. As will be described later, PRMV is a flag related to lens control, and is set to 1 when the lens is driven in the previous rAF control. Since we are talking about the first flow from turning on the switch SWI, the flag PRMV is O, and step (112)
to move to.

In step (112), the state of flag SRMV is detected, but SRMV is also a flag related to lens control, and since SRMV=O now, the process moves to step (129).

In step (129), a "focus detection" subroutine is executed. A flowchart of this subroutine is shown in FIG. 4(C), and within this subroutine, the focal state of the photographing lens is detected.

In the next step (130), a "judgment" subroutine is executed. The flowchart of this subroutine is shown in Figure 4 (
Shown in e). The "judgment" subroutine determines whether the lens is in focus or cannot detect the focus based on the result of the "focus detection" subroutine, and further sets the lens drive prohibition flag LMVDI to 1 if lens drive is not necessary.

In the next step (131), a "display" subroutine is executed to display in-focus or inability to detect focus. This involves communicating predetermined data to the display circuit DDR and displaying it on the display device DSP, but since this operation is not directly related to the present invention, further explanation will be omitted.

In step (132), the state of the flag LMVDI is detected. As mentioned earlier, when lens driving is not required, LMVDI is set to 1, so if LMVDI=1 in step (132), step (
133) and return to the ``rAF control'' subroutine. If the flag LMVDI is O, step (13
4), the state of the flag LCFLG is detected.

L CF L G is a low contrast flag that is set in the "one focus detection" subroutine of step (129), and is set to 1 when the contrast of the image signal is lower than a predetermined value. In step (134) LCFL
If G is 0, it means that the contrast is sufficient for focus detection, and after performing "lens drive" (described later) in step (135), the lens drive flag PRMV is set to 1 in step (136). , step (
137) and return to the ``rAF control'' subroutine.

If LCFLG is 1 in step (134), it is assumed that the contrast is low, and the process moves to step (138).

The steps after step (138) are the first control flow of a so-called "search operation."

Now, in Stella (138), the count value FC of the "distance ring counter" that communicates with the lens and counts the amount of movement of the focusing lens by the output pulse of the encoder linked to it.
NT is input from the intra-lens control device LPR3. This counter is reset to O when the power supply VL for the lens starts to be supplied, and is determined such that the extending direction is an up-count and the retracting direction is a down-count.

Therefore, the relative position of the focusing lens in the lens with respect to the optical axis direction can be known from the value FCNT of the distance ring counter.

In the next step (139), the count value FCNT
is stored in the conversion area LPO3 on the RAM inside the microcomputer PR3. This count value represents the relative position of the lens when starting the search operation,
As will be described later, this is used to return the lens to the search starting lens position when the search operation fails to detect a subject with sufficient contrast.

Subsequently, in step (140), a "close direction drive command" is sent to the lens, thereby starting a search operation. In response to this command, the lens drives the focusing lens toward close range. This command simply instructs the driving direction without specifying the driving amount, and when the focusing lens reaches its mechanical limit at the close end, the in-lens control circuit LP
R3 detects this and the lens itself stops driving. Note that the mechanical limit position is detected using encoder pulse 5EN.
It can be recognized by the time interval C. Step (141) Te sets variables 5RCNT and '7 lag SRMV to 1. 5RCNT is a variable that represents the state of the search operation, and is 0 when the search operation is not being performed, 11 when the lens is being driven in the close-up direction, and 2 when the lens is being driven in the infinity direction, which means that the lens is being driven toward the search start lens position. It is set to 3 when it is running. Since the lens is now driven in the close-up direction, the variable 5RCNT is set to 1. Further, SRMV is a flag indicating that the search operation has performed lens driving.

The first control of the search operation is performed in steps (138) to (141), and the "rAF control" subroutine is returned in steps (1, 4-2).

When the "rAF control" subroutine in step (006) in FIG. 4(a) is completed, the state of the switch SW1 is again determined in step (002). Here, SWI
If it is turned off, a drive stop command is sent to the lens in step (003). In other words, the previous rAF control”
Even if some kind of lens drive command is issued in the subroutine, the lens drive is stopped when the switch SWI is turned off. Then, in the next step (004), all flags are cleared.

If the switch SWI remains on in step (002), the "AF control" subroutine in step (005) is executed, and then the execution of the "rAF control" subroutine is started again in step (006).

The flow of the "AF control" subroutine while the switch SWI is on will be explained below, depending on the case.

First, a case will be described in which, in the "past rAF control" subroutine, lens driving was performed (flag PRMV is 1) with low contrast ((flag LCFLG is O).

When the "rAF control" subroutine is executed, step (
At step 108), the state of the flag PRMV is determined, and the process moves to step (109). In step (109), information on the lens driving state is inputted from the intra-lens control circuit LPR3 by communicating with the lens. If the predetermined drive has been completed and the lens has already stopped, the process moves to step (110) and after clearing the flag PRMV, step (129
) starts a new focus adjustment operation. If the lens has not stopped yet, proceed to step (111) and select "A".
The "F control" subroutine is returned. In other words, the past “
A new focus adjustment operation will not be performed until the lens has been driven by the amount instructed in step (135) of ``AF control''.

Next, a case will be described in which a search operation is performed (flag SRMV months) in the "previous rAF control" subroutine with low contrast (flag LCFLG is 1).

When the "AF control" subroutine is executed, step (
At step 112), the state of the flag SRMV is detected, and the process moves to step (113).

In step (113), information on the lens driving state is input from the lens, and if the lens has already stopped, step (113)
The process moves to step 19), and if driving is in progress, the process moves to step (114-). As mentioned above, the search operation is as follows: ■ Drive the lens in the closest direction (variable 5RCNT = 1
).

If the focusing lens reaches its mechanical limit on the close-up side without finding a contrasting object during driving in ■■, the lens will be driven in the infinity direction from now on (variable 5RCNT = 2
) If a contrasting object is not found during the drive of ■■ and the focusing lens reaches its mechanical limit on the infinity side, the lens will be driven to the search start lens position from now on (variable 5).
RCNT=3).

If the lens is being driven, in step (114) "
Execute the "Focus Detection" subroutine. This subroutine detects the amount of defocus and contrast of the subject. Next, in step (115), the state of the low contrast flag LCFLG is determined, and if LCFLG is 1 and the contrast is low, in step (117), the AF control subroutine is returned. That is, when focus detection is performed in the search operation, If the contrast is low, nothing will be done.If the flag LCFLG is 0 and it is determined that the contrast is not low, step (116)
, and sends a "drive stop command" to the lens. Next, after clearing the flag SRMV in step (118), new focus adjustment control is performed in step (129). That is, if the contrast is not low during focus detection during the search operation, that is, if the contrast is sufficient for focus detection, the lens is stopped, the search operation is ended (SRMV is set to O), and a new focus is detected. It makes adjustments.

If the contrast cannot be detected by the above-mentioned operation (2), return to the rAF control subroutine in step (117) every time the rAF control subroutine is executed until the focusing lens reaches its mechanical limit on the near side. become.

When the lens reaches the close end, it is detected in step (113) that the lens has stopped, and the process moves to step (119). Since we are now talking about the case of ■ above, step (120
). In addition, in the case of ■, step (119
) to step (123), where step (
124). In the case of ■, step here (1
18) and ends the search operation,
The case of ■■ will be described later.

Now, in step (120), 1 is added to the variable 5RCNT. This is because the lens has reached the close end and is then driven in the infinite direction.In the next step (121), an "infinite direction drive command" is sent to the lens, and the above search operation (2) is started. And in step (122) rAF
Returns the "control" subroutine. The control when contrast cannot be obtained during the operation of (①) is the same as in the case of (③) mentioned above.Every time the "AF control" subroutine is executed, the process returns to step (117) and the contrast is detected. The case is also the same as ■.

When the focusing lens of the lens reaches its mechanical limit on the infinity side, a stop of the lens is detected in step (113), and the process moves to step (123) via steps (1, 19).

Now the search operation is ■, so 5RCNT is 2,
The process moves from step (1, 23) to step (124). In step (124), 1 is added to the variable 5RCNT, thereby performing the search operation (2).

In step (125), the above-mentioned distance ring counter value FC is
Input NT, and in step (126) set LP0 to variable FP.
1-Stores the value of FCNT. The variable T-POS stores the value of the distance ring counter when the search operation is performed, and FP, which is obtained by subtracting the current counter value from the blur, is the distance ring counter value from the current lens position to the search start position. It represents. This FP is sent to the lens in step (127), and a command is given to drive the lens by an amount equal to FP based on the distance ring counter value.

That is, the lens is driven to the search start position.

Then, in step (128), the "rAF control" subroutine is returned. The control during the search operation (2) is the same as in the case of (2) described above.

When the focusing lens reaches the search start position, lens stop is detected in step (1, 13), and step (1,
19) and (123), clear the flag SRMV in step (118), and complete the search operation.
A new focus adjustment operation is started from step (129) onwards.

Next, the operation "rAF continuous shooting" in which the AF mode continues to turn on the switch SW2 in the servo mode will be described.

In this case, as described above, the release flag RLS is set to 1 in the "AF control" subroutine.

In the "rAF control" subroutine, step (105)
The state of the flag RLS is detected at step (
106). In step (106), all flags are cleared and all the states related to the past l'-AF control are initialized, and in the next step (1,07), the AF continuous shooting flutter FAF is set to 1, and then step The process moves to (129) and a focus adjustment operation is executed.

During AF quick shooting, the state of flags PRMV and SRMV related to lens drive and search operations is not determined.The reason for this and the lens drive specific to AF quick shooting are detailed in the "Lens Drive" subroutine. Describe.

To summarize the flow of the rAF control subroutine described above, when the rAF control subroutine is executed from the camera's main routine, focus detection is performed, and if the result is not low contrast, the lens is driven based on the defocus amount. A new focus adjustment operation is not performed until the lens has been driven by a predetermined amount. In the case of low contrast, the search operation is started, the lens is first driven in the closest direction, focus detection is performed while the lens is being driven, and if a contrasting object is detected, the lens drive is stopped and the lens is moved in the stopped state. Perform the focus adjustment operation again. When the lens reaches the close end without being able to detect contrast, it is driven in the infinity direction, and when it reaches the infinity end, it is driven to the search start position. If contrast is detected during this time, the lens is stopped and a new focus adjustment operation is performed, and when the lens reaches the search start position without contrast being detected, the search operation is ended there.

FIG. 4(C) shows a flowchart of the "focus detection" subroutine.

In step (202), an "image signal manual" subroutine is executed, and the image signal from the sensor device SNS is stored in a predetermined area within the microcomputer. A flowchart of the "image signal input" subroutine is shown in FIG. 4(d), which will be described later.

Next, in step (203), the defocus amount DEF and contrast ZD of the photographing lens are calculated from the already stored image signals. The specific method is disclosed in the patent application filed in 1983 by the present applicant. -160824 etc., so
Detailed explanation will be omitted.

In step (204), three flags JFFLG, CH
3FLG.

Cleared LCFLG. In step (205), contrast amount ZD and predetermined 1tLCLVL are compared, and if ZD < L CL V L, step (2
06) and sets the flag L CF L G to 1. That is, the contrast amount ZD is the predetermined amount r−cr
-v r-, low contrast flag L
Set CFLG to 1. and step (20
Step 8) returns the "focus detection" subroutine.

If ZD≧LCLVL in step (205), proceed to step (207) and defocus y D F
Compare the F absolute value and the predetermined amount CHS FLD, and
If EF1〉CHS FLD, step (208)
to return to the "focus detection" subroutine.

In step (207) l DEF l≦CH3F
If it is LD, flag CH3 is set in step (209).
Set FLG to 1. That is, if the contrast is sufficient and the defocus amount is within the near-focus range represented by CHS FLD, the near-focus flag CHS FLD is set.
Set LG to 1.

Next, in step (210), IDEFl is compared with the predetermined amount JFFLD, and l DEF l > JFFLD
If so, proceed to step (211) and return to the "focus detection" subroutine, and if IDEFI≦JFSFLD, set the flag JFFLG to 1 in step (212), and then execute the "focus detection" subroutine in step (213). Return. That is, the amount of defocus is J F
If it is within the focus range represented by FLD, a focus range flag JFFLG is set to 1.

As described above, in the "focus detection" subroutine, the defocus amount and contrast of the photographing lens are detected, and the low contrast flag LCFLG is cleared to 1 if the contrast is low, and to O if the contrast is sufficient. Furthermore, if the defocus amount is close to the in-focus amount, the flag CI(S
If FLG is in the in-focus area, the flag JFFLG is set to 1 and the process returns.

FIG. 4(d) shows a flowchart of the "image signal input" subroutine.

When the "image signal input" subroutine is executed, the state of the AF continuous shooting flutter FAF is determined in step (302), and if FA'F is 1, the predetermined position MXITF is stored in the variable MAXtNT in step (304). do. M.A.
XINT is a variable that defines the maximum accumulation time of the sensor in units of 1 millisecond, and has the relationship MXITN > MXITF. Therefore, the maximum accumulation time is set short for the AF continuous shooting time.

In the next step (305), the sensor device SNS is caused to start accumulating optical images. Specifically, microcomputer PR
3 sends an "accumulation start command" to the sensor drive circuit SDR, and SDR sets the clear signal CLR of the photoelectric conversion element section of the sensor device SNS to L° to start accumulating charges.

In step (306), an accumulation time counter INTCNT set on the RAM is initialized to zero.

In step (307), the 1 millisecond clock timer is reset. Note that this 1 millisecond clock timer utilizes the timer function of the microcomputer PR3.

In step (308), the state of the input INTEND terminal of PR3 is detected to check whether or not accumulation has ended. The sensor drive circuit SDR outputs the signal INTEND at the same time as the start of accumulation.
is set to L°, monitors the AGC signal 5AGC from SNS, and when 5AGC reaches a predetermined level, the signal INTE
It has a structure in which the charge in the photoelectric conversion element section is transferred to the CCD section by setting ND to 'H' and simultaneously setting the charge transfer signal SH to 'H' for a predetermined period of time.

If the INTEND terminal is "H" in step (308), it means that the accumulation has finished, and the process moves to step (313); if it is L°, it means that the accumulation has not finished yet, and the process moves to step (309). If not, check whether the 1 millisecond timer reset earlier has counted 1 millisecond in step (309).If 1 millisecond has not elapsed, proceed to step (308), and check whether the accumulation has finished or not. Wait for 1 millisecond to elapse, and if 1 millisecond elapses before the accumulation ends, proceed to step (310).Step (3)
10), the accumulation time counter INTCNT is counted up by one, and the process proceeds to step (311).
In step 1), the counter INTCNT and the variable MAXINT are compared. MAXINT is the maximum accumulation time expressed in units of 1 millisecond as described above, and if INTCNT is less than M A X I'NT, step (307
) and waits for the accumulation to finish again. INTCNT is M
If it matches AXINT, move to step (312),
Force storage to end. The forced storage termination is executed by sending an "accumulation termination command" from the microcomputer PR3 to the sensor drive circuit SDR. SDR is PH
When the "accumulation end command" is sent from 1, the charge transfer signal SH is set for a predetermined time ゛I]' to transfer the charge in the photoelectric conversion unit to C.
Transfer it to the CD section. The sensor accumulation ends in the flow up to step (312).

Step (31, 3) is the image signal of the sensor device SNS○
A/ of signal AO3 obtained by amplifying S with sensor drive circuit SDR
Performs D conversion and stores the digital signal in RAM.

To explain in more detail, the SDR generates the COD driving clocks φJ and φ2 in synchronization with the clock CK from PH1 and supplies them to the control circuit 5SCNT inside the SNS.
The CCD section is driven by φl and φ2, and the charges in the CCD are outputted in time series from the output O8 as an image signal. After this signal is amplified by an amplifier inside the SDR, it is input as AO3 to the analog input terminal of PH1. The PH1 performs A/D conversion in synchronization with the clock CK that it outputs, and sequentially stores the digital image signals after A/D conversion at predetermined addresses in the RAM.

After inputting the image signal in this way, step (3)
At step 14), the "image signal manual power" subroutine is returned.

FIG. 4(e) shows a flowchart of the "judgment" subroutine.

At step (4,02), three flags JF, AFNG
.

Clear LMVDI. As will be described later, JF is a flag representing the in-focus state, AF and NG are flags representing that focus detection is impossible, and LMVD1 is a flag for prohibiting lens driving.

In step (4, 03), the state of the focus area flag JFFLG that is set in the "focus detection" subroutine is determined, and if it is , it is determined that the focus is in focus, and step (4, 03) is performed.
04,) to control the focusing state. Step (
404) Then, both the focus flag JF and the lens drive inhibition flag LMVDI are set to 1. Next step (40
In 5), the constant 5RCNT is cleared. As mentioned above, 5RCNT is a variable that represents the state of the search operation;
RCNT-0 means a state where no search operation is being performed. That is, when the object is in focus, the result is the same as when no search operation is performed, and when the contrast becomes low, the search operation is performed again. Subsequently, in step (406), the flag TMACT is set to 1.

TMACT will be described later. This flag indicates that the lens drive regulation timer is in operation. Step (407)
The timer is restarted at step (408), and the "judgment" subroutine is returned.

The lens drive regulation timer is a timer that uses the internal timer of the microcomputer PR8, and starts counting from the time it is restarted, and its contents can be read at will.

If the focus area flag JFFLG is O in step (403), the process moves to step (409), and the low contrast flag L C set in the "focus detection" subroutine is
Determine the state of FLG. If the flag L CF L G is 1 in step (409), it is assumed that the focus detection result is low contrast, and step (410)
Move to.

In step (410), the search operation state variable 5RCNT
The state is detected, and if it is not 0, the process moves to step (411). The fact that the variable 5RCNT is not 0 means that
This indicates that a search operation has been performed since the switch SW] was turned on, or that it has been forcibly set as such by focusing as described above. In this case, the step (411) sets the focus detection failure flag AFNG to ), and then moves to the next step (
412), the lens drive prohibition flag LMVDI is set to 1. If the flag LMVDI is 1, in step (132) of the rAF control subroutine in FIG. It will not be done.

If the variable 5RCNT is 0 in step (4, 10), the process moves to step (414) and the continuous shooting AF flag FA
Detects the state of F.

In step (41, 4,), if the flag FAF is 1, that is, continuous shooting AF, the process moves to step (4, 12), and the flag LM
Set VDI to 1 to disable search operation.

When the flag FAF is O, the process moves to step (415), in which case a search operation is performed in the "AF control" subroutine.

Low contrast I-CF L G in step (409)
is 0, that is, the contrast is sufficient, step (415)
Move to.

In step (415), the in-focus vicinity flag CI-I
If SFLG is 1, the process moves to step (416) and returns to the "determination" subroutine. Step (41
If the flag CHS F L G is 0 in step 5), it is determined that the defocus amount is not near the in-focus area, and step (42
Move on to 6).

In step (426), the continuous shooting AF flag FAF is determined. Here, if the flag FAF is l and the continuous shooting AF state is established, the process moves to step (412), otherwise the process moves to step (417). That is, if the focus state is not near the in-focus state and it is a quick shooting AF state, step (412
), lens driving based on the amount of defocus at this time is prohibited.

In step (417), the state of the lens drive regulation control timer operation flag TMACT is determined, and if it is 0 and inactive, the process moves to steps (4, 18) and returns to the "determination" subroutine. If TMACT is 1 and is in operation, the process moves to step (4, 19) and the subsequent lens drive regulation timer is controlled. In step (419), the state of the low contrast flux LCFLG is determined, and if it is l, the process moves to step (4, 12), and the predetermined constant WT is set to variable TMLNG.
Store TMLC. If the flag LCFLG is O, the process moves to step (420), and a predetermined constant WTTM is stored in the variable TMLNG. TMLNG is a variable that specifies the operation time of the lens drive regulation timer, and WTTM is a constant.
<There is a relationship with WTTMLC.

If the lens drive regulation timer that starts counting when the lens is in focus is less than the above TMLNG, lens drive based on the defocus amount is prohibited, and if TMLNG is exceeded, lens drive is permitted, so the focus detection result When the contrast is low, the time from focusing to performing the search operation is longer than when the contrast is low.

In step (422), the value of the lens drive regulation timer being counted is compared with the variable TMLNG, and if the former is larger, the process moves to step (424), the lens drive regulation timer operation flag TMACT is cleared, and step (424)
) returns the "judgment" subroutine. Step (
4. If the latter is larger in step (4.22), the process moves to step (4.23), sets the lens drive prohibition flag to 1, and makes a "determination" in step (425).
Return subroutine.

To summarize the flow of the "judgment" subroutine explained above, if the focus detection result is in the in-focus area, the focus flag JF
is set to 1, and the lens drive prohibition flag LMVDI is set to 1.
Set to 1. Then, while the switch SWI is on, the search operation is performed again when the contrast becomes low.
At the same time, the lens drive regulation timer is activated. If the focus detection result is low contrast, a search operation is performed, but if a search operation has been performed since the switch SWI was turned on, the search operation is not performed again, and the focus detection failure flag AFNG is set. Set the lens drive prohibition flag LMVDI to 1. However, even in low contrast, no search operation is performed in the case of quick-shooting AF.

When the lens cannot be focused even if the contrast is sufficient, and the defocus amount is within the range near the focus, the lens is driven regardless of the operation of the lens drive regulation timer.

If the defocus amount is larger than the in-focus range or when searching with low contrast, if the lens drive regulation timer does not operate in a state other than the quick-shooting AF state, the lens will continue to drive. If the lens drive regulation timer, which does not drive the lens regardless of the operating state, is in operation, two times that differ depending on the contrast are compared with the timer value at which time measurement is started if the time is in-focus.

In other words, if a defocus amount larger than the range near focus is detected, the lens will not be driven for a predetermined time (defined by the constant WTTM) from the time of focus, and even if a search operation is performed with low contrast, the lens will not be driven for a predetermined time from the time of focus (defined by the constant WTTM). (Constant WT longer than WTTM
TMLC) will not be searched.

FIG. 4(f) shows a flowchart of the "Luns Drive" subroutine.

When this subroutine is executed, step (502)
communicates with the lens at , and sends two data rsJrPT
Input I(J. "S" is the "coefficient of defocus amount vs. focus adjustment lens extension amount" specific to the photographing lens,
For example, in the case of an entirely projecting single lens, the entire photographic lens is a focusing lens, so S=], and in the case of a zoom lens, S changes depending on each zoom position. rPTHJ is the output of the encoder ENC which is linked to the movement of the focusing lens LNS in the optical axis direction] and is the amount of protrusion of the focusing lens per pulse.

Therefore, the current defocus amount DEF of the photographic lens.

A value obtained by converting the amount of protrusion of the focusing lens into the number of output pulses of the encoder using the above S and PTH, so-called lens drive fiFP, is given by the following equation.

FP=DEFXS/PTH Step (503) executes the above equation as is.

In step (504), F obtained in step (503)
Sends P to the lens to command the driving of the focusing lens (the entire focusing lens (in the case of an extended single lens, the entire photographing lens),
In the next step (505), the "lens drive" subroutine is returned.

〔Effect of the invention〕

As described above, according to the present invention, when the focus detection result is in focus or near focus, the lens is driven immediately if the subsequent defocus amount is within a predetermined amount,
When the amount exceeds a predetermined amount, lens driving is prohibited within a first predetermined time from the time when the focus is in focus or near focus;
When the subject performs a search operation with low contrast, the search operation is prohibited during a second predetermined time period that is longer than the first predetermined time period, which improves operability especially when a telephoto lens is attached. Focus adjustment becomes possible.

[Brief explanation of the drawing]

Fig. 1 is a diagram of the optical principle of the focus adjustment device of the present invention, Fig. 2 is a waveform diagram showing the output states of the sensors SAA and SAB in Fig. 1, and Fig. 3 is an example of a camera using the present invention. FIGS. 4(a) to 4(f) are explanatory diagrams showing a program for explaining the operation of a camera using the present invention. PH1・・・・・・・・・・・・・・・・・・・・・
・・・・・・Microcomputer LCM・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
Lens communication buffer circuit FLNS...
・・・・・・・・・・・・・・・・Lens LNS...
・・・・・・・・・・・・・・・・・・・・・・・・
・Focus adjustment lens LPR3・・・・・・・・・・・・・
・・・・・・・・・・・・Lens control circuit SNS・
・・・・・・・・・・・・・・・・・・・・・・・・
...Sensor device SDR...
・・・・・・・・・・・・・・・Sensor drive circuit patent applicant Canon Co., Ltd. Yama” ↓” Eyo i Procedural amendment (voluntary) January 14, 1988 2 Name of invention automatically Relationship between focus adjustment device 3 and the case of the person making the correction Patent applicant address 3-30-2 Shimomaruko, Ota-ku, Tokyo Name (100
) Canon Co., Ltd. Representative Ryuzo Kaku
Section 4 Agent Address: Canon Co., Ltd., 3-30-2 Shimomaruko, Ota-ku, Tokyo 146 (telephone: 758-2111) 5. Statement of the subject of amendment 6. The full text of the statement of contents of the amendment shall be amended as attached. Description 1, Title of the invention Automatic focus adjustment device 2, Claims (]) The light flux from the subject that has passed through the photographic lens is received by a plurality of photoelectric conversion element arrays, and the output of the photoelectric conversion element array is detecting the defocus amount of the photographing lens and determining the reliability of the detected defocus amount, and if the reliability is high, driving the photographing lens based on the detected defocus amount. In a camera focus adjustment device, which performs a second lens drive that drives the photographic lens regardless of the detected defocus amount when the reliability described in 1. is low, (If the detected defocus amount is smaller than the predetermined amount, immediately perform the first lens drive,
1. When the reliability is high and the detected defocus amount is larger than the predetermined amount, the focus adjustment device
1. The first lens drive is prohibited within a first predetermined time period from the time when it is detected that the focus state of the photographing lens is in focus or near focus, and when the reliability is low, the second lens drive is prohibited from the above point in time. A focus adjustment device for a camera, characterized in that driving of the second lens is prohibited during a predetermined period of time. (2) The camera focus adjustment device according to claim (1), wherein the first predetermined time is shorter than the second predetermined time. 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a focus adjustment device for a camera or the like. [Prior Art] Conventionally, as one type of camera focus adjustment device, the exit pupil of a photographic lens is divided into two by an optical system for focus detection, and two objects are formed by the light flux that passes through each pupil area. The image is received by a photoelectric conversion element array (for example, a CCD sensor array), and the focal state of the photographing lens is detected from the output thereof.
A method is known in which a photographic lens is driven based on the detection result. In the focus detection operation described above, if the contrast of the subject image is sufficient, highly accurate focus detection is possible, but contrast focus detection becomes impossible, so as a countermeasure,
A so-called "search operation" is often performed in which the photographing lens is driven regardless of the detection result in the hope that the contrast of the subject will increase. This is because the contrast may be low because the contrast of the subject is essentially low, or because the amount of defocus of the photographic lens is large, resulting in low contrast. However, the above search operation normally drives the photographing lens one round trip from the closest end to the infinity end of the distance ring, so if a telephoto lens is attached, the subject may be moved within the viewfinder due to camera shake, etc. However, when the camera deviates from the so-called distance measurement frame, the contrast is low and it takes a long time to refocus on the subject after reciprocating. [Purpose] The present invention aims to solve the above-mentioned problems, and its gist is that when the focus detection result is in focus or near focus, the lens is driven immediately if the subsequent defocus amount is within a predetermined amount. , when the amount exceeds the predetermined amount, lens driving is prohibited within a first predetermined time period from the point of focus or near focus, and when the subject performs a search operation with low contrast, the lens drive is prohibited for the first predetermined time period. By prohibiting the search operation during the second predetermined time period, which is longer than the second predetermined time period, it is possible to perform focus adjustment with improved operability, especially when a telephoto lens is attached. [Example] First, the principle of focus detection in the present invention will be explained with reference to FIG. A field lens FLD is disposed on the same optical axis as the photographing lens LNS to be focus-detected. Two secondary follow-up lenses FCLA and FCLB are disposed behind it at symmetrical positions with respect to the optical axis. Furthermore, sensor arrays SAA and SAB are arranged behind it.Apertures DIA and D are located near the secondary continuous image lenses FCLA and FCLB.
An IB will be provided. The field lens FLD forms two secondary images on the exit pupil of the photographing lens LNS.
, is almost imaged on the pupil plane of FCLB. As a result, the light beams incident on the secondary imaging lenses FCLA and FCLB are emitted from regions of equal area that do not overlap with each other and correspond to the respective secondary imaging lenses FCLA and FCLB on the exit pupil plane of the photographing lens LNS. It becomes what is given. The aerial image formed near the field lens FLD is transmitted to the sensor array SAA,
When the image is re-formed on the surface of SAB, the positions of the two images on the sensor arrays SAA and SAB are considered based on the displacement of the aerial image position in the optical axis direction. Therefore, by detecting the amount of displacement (shift) in the relative positions of the two images on the sensor array, it is possible to know the focal state of the photographic lens L N S. FIG. 2 shows an example of photoelectric conversion outputs of two images formed on the sensor arrays SAA and SAB. The output of SAA is A (i),
Let the output of SAB be B (i). In this example, the number of pixels of the sensor is 40 pixels (i = O,..., 39
). A signal processing method for detecting the amount of image shift PR from image signals A (i) and B (i) is disclosed in Japanese Patent Application Laid-Open No. 58-142.
No. 306, JP-A-59-10'7313, JP-A-60-101513, or Japanese Patent Application No. 1983-
No. 160824 and the like are disclosed by the present applicant. By adjusting the focus of the photographic lens based on the amount of image shift obtained by the methods disclosed in these publications, it is possible to bring the photographic lens into focus. FIG. 3 is a circuit diagram showing an embodiment of a camera equipped with an automatic focusing device according to the present invention. In the figure, PRS is a camera control device that includes, for example, a CPU (central processing unit), ROM, and RAM. EEPROM (Electrically Erasable Programmable RO
M) is a one-chip microcomputer with A/D conversion function, which performs camera functions such as automatic exposure control function, automatic focus detection function, and film winding/rewinding according to the camera sequence program stored in ROM. is performing an action. EEFROM is a type of non-volatile memory.
Various adjustment data are written in the process. Computer PR3 has communication signals so, sr, 5CLK
is used to communicate with peripheral circuits and lenses, and to control the operation of each circuit and lens. So is a data signal output from computer PR5,
SI is a data signal manually input to the computer PRS, 5
CLK is a synchronization signal for signals So and SI. The LCM has a lens communication buffer circuit, and when the camera is in operation, the lens power supply VL is applied to the lens, and the signal CLCM from the computer PR3 is at a high potential level ('H').
), it becomes a buffer for communication between the camera and lens. Computer PR3 sets CLCM to °H' and 5C
When predetermined data is sent from So in synchronization with LK, the buffer circuit LCM transmits 5
Buffer signals LCK and DCL of CLK and So are output to the lens. At the same time, the signal DLC from the lens
outputs the buffered signal as SI and sends it to the computer PR.
3 inputs lens data such as the SI flaw signal in synchronization with 5CLK. SDR is a drive circuit for the line sensor device SNS for focus detection, and is selected when the signal C5DR is °H°,
Controlled from PR3 using o, SI, 5CLK. The signal CK is the CCD driving clock φ1. The signal INTEND is a clock for generating φ2, and the signal INTEND is a signal that notifies the computer PR3 that the storage operation has ended. The output signal O3 of the device SNS is clock φ1. A time-series image signal synchronized with φ2 (the sensor array SA of the sensor device)
The accumulated image signal at each pixel of the image light received at each pixel of A and SAB) is amplified by the amplifier circuit in the SDR,
It is output to the computer PRS as an AO3 signal. Computer PR3 manually inputs the AO3 signal from the analog input terminal, synchronizes with CK, and converts it to A/D using the internal A/D conversion function.
After D conversion, the data is sequentially stored at a predetermined address in the RAM. Same < AGC, which is the output signal of the SNS device, is the output signal of the device S
This is the output of the AGC control sensor in the NS, and the drive circuit S
Each sensor SAA, SA of the device SNS is input to DR.
It is used to control the accumulation of image signals in B. A series of operations of the circuit SDR will be falsified later. spc is a photometric sensor for exposure control that receives light through the photographic lens, and its output 5spc is sent to computer P.
The signal is input to the analog input terminal of R3, and after A/D conversion is used for automatic exposure control (AE). DDR is a switch sense and display circuit, which is selected when signal CDDR is H' (7), so. Controlled by computer PR5 using Sr, 5CLK. That is, based on the data sent from the computer PR3, the display on the display member DSP of the camera is switched, and the release button (not shown) (switch SW1.SW
The computer PR3 is informed of the on/off states of the switch group SWS that is linked to various operating members such as the mode setting button (linked to the switch 2) and the mode setting button. MDRI9MDR2 is a drive circuit for film feeding and shutter charge motors MTRI and MTR2, and the signal MT
Execute forward/reverse rotation of the motor with F, MIR, M2F, and M2R. MGI and MG2 are magnets for starting the movement of the front and rear curtains of the shutter, respectively, and the amplification transistors TR1 and TR2 are energized by the signals 5MG1 and 5MG2, and the shutter control is performed by the computer PR3. The switch sense and display circuit DDR, motor drive circuit MDRI, MDR2, and shutter control are as follows:
Since this is not directly related to the present invention, detailed explanation will be omitted. A signal DCL input manually to the lens drive circuit LPRS in synchronization with the LCK signal is data of a command from the camera to the lens FLNS, and the operation of the lens in response to the command is determined in advance. LPR3 analyzes the instruction according to a predetermined procedure,
It performs focus adjustment and aperture control operations, and outputs various lens parameters (open F number, focal length, defocus amount vs. extension amount coefficient, etc.) from the output DLC. In the embodiment, an example of a single lens that is fully extended is shown, and when a focus adjustment command is sent from the camera, the focus adjustment motor LMTR is activated by the signal LMF, according to the driving amount and direction sent at the same time. Driven by LMR,
Focus adjustment is performed by moving the optical system in the optical axis direction. The driving amount of the optical system is monitored by the pulse signal 5ENC from the encoder circuit ENC, which is composed of a pulse plate, etc., which rotates in conjunction with the optical system and outputs several pulses according to the driving amount, and outputs several pulses according to the driving amount. When a predetermined movement is completed, the signals LMF and LMR are set to 'L' to brake the motor LMTR. 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. The operation of the camera with the above configuration will be explained according to the flow shown in FIG. 4. When a power switch (not shown) is operated, power supply to the microcomputer PRS is started, and PRS stores ROMkm.
Start execution of the stored sequence program. FIG. 4(a) is a flow chart showing the overall flow of the above program. When execution of the program is started by the above operation, the state of the switch SWI, which is turned on at the first stroke of the release button, is detected in step (002), and if the switch SW1 is off, in step (003), Computer PR5 to CL
An instruction to stop driving is given by setting CM to H' and sending a "drive stop command" to the lens as an SO signal via circuit LCM. Next step (004
), all control flags and variables set in the RAM in the PRS are cleared. The above step (002
), (003), (004) are executed repeatedly until the switch SWI is turned on or the power switch is turned off. Therefore, even if the lens is being driven, the SW
When I is turned off, the lens will stop driving. Note that the state of the switch SWI is detected by changing the signal CDDR to °H.
'' is specified in the circuit DDR, and the detection command of the switch SW1 is sent as an SO signal to the circuit DDR, and the detection command of the switch SW1 is transmitted to the circuit DDR.
This is executed by detecting the state signal of switch S'W1 at R and transmitting it to the computer PRS as an Sl signal. When the SWI is turned on, the process moves to step (005). Step (005) means the "rAE control" subroutine. In this "rAE control" subroutine, a series of camera operation controls such as photometric calculation processing, exposure control, shutter charging after exposure, and film winding are performed. Note that the rAE control j subroutine is not directly related to the present invention, so a detailed explanation will be omitted, but an outline of the function of this subroutine is as follows. While SWl is on, this "rAE control" subroutine is executed, and photometry and exposure control calculations and display are performed each time. When the switch SW2 is turned on by the second stroke of the release button (not shown), the microcomputer PR3
The release operation is started by the interrupt processing function of
The aperture or shutter speed is controlled based on the exposure amount determined by the exposure control calculation, and after the exposure is completed, shutter charging and film feeding operations are performed to complete one darkest image of one film frame. Note that the camera according to the embodiment of the present invention has two AF modes, so-called "one-shot" and "servo" modes. When the AF mode is one-shot, once the camera is in focus, the focus adjustment operation will not be performed again until the switch SWI is turned off, and the shutter cannot be released until the camera is in focus. In the case of servo mode, focus adjustment is continued even after focusing, and release is possible at any time regardless of the focus detection result. Therefore, the above-mentioned interrupt processing is permitted when focus is achieved in the case of one-shot, and is permitted at any time in the case of servo, but it is temporarily prohibited after the release operation, and after execution of the "rAF control" subroutine in the next step (006). allowed again. Selection of one-shot servo is made by a mode selection switch (not shown). As mentioned earlier, the release operation is performed by turning on switch SW2, but even if SW2 is left on even after one frame of film has been shot, the rAE control returns as having been terminated. . Therefore, SW
To explain the operation with 2 turned on, in the case of one shot, you cannot release the camera until it comes into focus. Once it comes into focus, you can only release the camera and take a single frame. After that, since it is a one shot, you can adjust the focus. Instead, the next frame is photographed with the same lens position, and photographing continues as long as the switch SW2 is on. Even in the case of servo, it is possible to release the camera, so when SW2 is turned on, photography is immediately performed. Then, after one parfocal adjustment is performed in the ``rAF control'' routine, the release is enabled again and shooting is performed, and in the end, while SW2 is on, ``release operation'' and ``AFIJ control'' are alternately performed. It will be repeated. This situation is called rAF continuous shooting J, and in order to recognize this situation in the rAF control routine described later, a flag called RLS is set to 1 after the release operation in the rAE control j subroutine. I'll keep it. Now, as mentioned above, in step (005) r
When the “AE control” subroutine ends, step (00
6) rAF control subroutine is executed. FIG. 4(b) shows a flowchart of the "rAF control" subroutine. First, in step (102), the AF mode state is detected. This is switch sense circuit D
This is done by knowing the state of the AF mode setting switch (not shown) by communicating with the DRT in the same manner as the detection of the switch SWI. If the AF mode is one-shot, the process moves to step (103) and the state of the flag JF is detected. As will be described later, JF is a flag indicating the focus state that is set in the "judgment" subroutine of step (130).
Checking the flag JF in step 103) means checking the previous focus state. Here flag JF is 1
If so, since the previous focus was achieved, the process moves to step (104) and returns to the ``rAF control subroutine''. That is,
In one-shot mode, once the focus is focused, switch SWI
No new AF control will be performed until the flag is turned off and all flags are cleared in step (004). "The first rAF control after turning on the switch SWI" is of course flag J.
Since F has been cleared, the process goes to step (108) for eight lines. If it is the servo mode in step (102), the process moves to step (105). In step (105), the state of the flag RLS is detected. RLS is a flag that is set in the "rAE control" subroutine as described above, and is set after the release operation. If the flag RLS is set to 1 in step (105), it is recognized that it is immediately after release in servo mode, that is, rAF continuous shooting, and step (105) is performed.
106). rAF continuous shooting", first clear all flags in step (10B), then set flag FAF to 1 in step (107), and then proceed to step (129). Since release is possible at any time in servo mode, it is possible for the program to process an interrupt and transition to the release operation routine at any step in the program. Step (1)
06), all flags are cleared. FAF
is a flag that recognizes continuous shooting AFj in the rAF control subroutine. If the flag RLS is O in step (105), the process moves to step (108). In step (10B), the state of the flag PRMV is determined. As will be described later, PRMV is a flag related to lens control, and is set to 1 when the lens is driven in the previous rAF control. Since we are currently talking about the first flow from switch SWI, the flag PRMV is 0, and the process moves to step (112). In step (112), the state of flag SRMV is detected, but SRMV is also a flag related to lens control, and since SRMV=O now, the process moves to step (129). In step (129), a "focus detection" subroutine is executed. A flowchart of this subroutine is shown in FIG. 4(c), and within this subroutine, the focal state of the photographing lens is detected. In the next step (130), a "judgment" subroutine is executed. The flowchart of this subroutine is shown in Figure 4 (
Shown in e). The "judgment" subroutine determines whether the lens is in focus or cannot detect the focus based on the result of the "focus detection" subroutine, and further sets the lens drive prohibition flag LMVDI to 1 if lens drive is not necessary. In the next step (131), a "display" subroutine is executed to display in-focus or inability to detect focus. This is similar to the communication of the switch SW1 mentioned above.
Predetermined data is communicated to R and displayed on the display device DSP, but since this operation is not directly related to the present invention, further explanation will be omitted. In step (132), the state of the flag LMVDI is detected. As mentioned earlier, if there is no need to drive the lens, LKVDI is set to 1, so step (
132), if LMVDI=1, step (13
The process moves to step 3), and the rAF control routine turns. If the flag LMVDI is O, step (134
), the state of the flag LCFLG is detected. LCFLG is a low contrast flag set in the "focus detection" subroutine of step (129), and is set to 1 when the contrast of the image signal is lower than a predetermined value. In step (134), LCFLG is set to O.
If so, it means that the contrast is sufficient for focus detection, and after performing "lens drive" which will be described later in step (135), lens drive flags PR and MV are set to 1 in step (13B). Step (13
In step 7), return to the "rAF control" subroutine. If LCFLG is 1 in step (134), it is assumed that the contrast is low, and the process moves to step (138). The steps after step (138) are the first control flow of a so-called "search operation." Now, in step (138), the count value FCNT of the "distance*ii counter" that communicates with the lens and counts the above-mentioned output pulses from the encoder ENC linked to the movement amount of the focusing lens is input to the in-lens control device LPR3. From human power. This counter is reset to O when the lens power supply VL starts supplying power, and when the lens is moving in the extending direction, the above pulse is counted up, and when it is moving in the retracting direction, it is counted down, and so on. ing. Therefore, the relative position of the focusing lens in the lens with respect to the optical axis direction can be known from the count value FCNT of the distance ring counter. In the next step (139), the count value FCNT
is stored in the conversion area LPO3 on the RAM inside the microcomputer PR3. This count value represents the relative position of the lens when starting the search operation,
As will be described later, this is used to return the lens to the search starting lens position when the search operation fails to detect a subject with sufficient contrast. Subsequently, in step (140), a close direction drive command j is sent to the lens and transmitted to the circuit LPR3 via the circuit LCM as described above, thereby starting the 201 operation. In response to this command, the focusing lens is driven toward the close-up direction.In addition, when the driving command is issued toward the close-up direction, the circuit LPR5 moves the LMF to °H°.
It is assumed that the motor LMTR is rotated in the normal direction to drive the lens in the near direction, and in response to a drive command in the infinity direction, the LMR is set to °H' and the motor is rotated in the reverse direction to drive the lens in the infinity direction. This command simply instructs the driving direction without specifying the driving amount. When the focusing lens reaches its mechanical limit at the close end, the lens control circuit LPR3 detects this and the lens itself stops driving. Note that the mechanical limit position is detected by encoder pulse 5E even though a lens drive command has been issued.
When NC does not occur for a predetermined period of time or more, it is recognized that the lens has moved to the limit position, and lens driving is stopped. Step (14
In 1), the variable 5RCNT and the flag SRMV are set to 1. 5RCNT is a variable that represents the state of search operation,
It is set to 0 when a search operation is not being performed, 1 when the lens is being driven in the close-up direction, 2 when the lens is being driven in the infinite direction, and 3 when the lens is being driven toward the surge start lens position. Now, after driving the lens in the close-up direction, the variable 5RCNT is set to 1. Further, SRMV is a flag indicating that the search operation has performed lens driving. Steps (138) to (14)
Initial control of the search operation is performed in step 1), and step (
142) and return to the ``rAF control'' subroutine. As described above, in the first AF control subroutine after switch SW1 is turned on, the lens is driven at the time of focusing according to the focus state determined in steps (129) and (130), regardless of the one-shot mode or servo mode. The AF control is immediately returned without changing the focus, and when the defocus amount is detected due to out of focus, step (135) is executed.
), the lens is driven in the focusing direction according to the defocus, and then the AF sub-control is returned.Also, when a low contrast judgment is made, the lens is driven to the closest direction, a search operation is performed, and then the AF control is returned. . When the above-mentioned "AF control" subroutine of step (006) in FIG. 4(a) is completed, step (002)
The state of the switch SWI is determined in the step SWI. Here, S
If Wl is turned off, a drive stop command is sent to the lens in step (003). That is, even if some lens drive command was issued in the previous rAF control j subroutine, lens drive is stopped when the switch SW1 is turned off. Then, in the next step (004), all flags are cleared. If the switch SW1 remains on in step (002), after executing the "rAF control" subroutine in step (005), the "AF control" subroutine is started again in step (006). The flow of the ``rAF control after the second time while the switch SWI is on'' subroutine will be explained below, depending on the case. First, in the "past rAF control" subroutine, if the contrast was not low (flag LCFLG was O) and the lens was driven (flag PRMV was 1), that is, the lens was driven in the focusing direction when out of focus. Let's talk about the case. When the "rAF control" subroutine is executed, step (
A mode determination is made in step 102). The out-of-focus judgment was made last time, the flag JF is O, and the switch S is still on.
Since W2 is not on and no release operation is being performed, the step moves to (108) regardless of whether the mode is one-shot mode or servo mode. In step (108), the state of the flag PRMV is determined, and the process moves to step (109). In step (109), the computer PR3 sets CLCM to °H'', and the circuit L
It is transmitted to the circuit LPR5 via CM, communicates with the lens,
Information on the lens drive state is input from the intra-lens control circuit LPR3. That is, the control circuit uses a counter to count the pulses from the encoder ENC, and when the count value matches the number of pulses corresponding to the defocus amount obtained in the focus detection subroutine, the signal LM is output.
F, LMR is set to L' to stop the motor LMTR and stop the lens drive, and when the control of the lens drive amount according to the defocus amount is completed, a lens stop signal is formed internally, and the step ( 109) In the above communication, this lens stop signal is sent to computer PR3.
is input, and it is determined whether the lens has finished driving by the amount of defocus. If the predetermined drive has been completed and the lens has already stopped, the process moves to step (110) and after clearing the flag PRMV, step (12
9) Start a new focus adjustment operation. If the lens has not stopped yet, proceed to step (111).
AF control" subroutine is returned. In other words, a new focus adjustment operation will not be performed until the lens has been driven by the amount instructed in step (135) of "Past rAF Control", and step (129) will not be performed until the lens drive is completed. ) and subsequent new focus adjustment operations are performed. In addition, in steps (129) and (130) of the new focus adjustment operation after step (129), when it is determined that the lens has moved to the in-focus position in the previous lens drive and is in the in-focus state, the flag JF is set. Set LMVDI to 1 and AF
The control subroutine is returned and the lens is maintained in the focused position. Also, after this AF control subroutine returns, the process moves to step (006) again, and when the AF control subroutine is executed, step (006) is executed in the one-shot mode.
Since 1 of flag JF is detected at step 103), from now on A
Even if the F control subroutine is repeated, no focus detection/judgment operation is performed, and the lens continues to be held at the once focused position. In addition, in the servo mode, the above steps (105), (108), and (112) are performed every time AF control is executed.
), (129) and subsequent steps are repeated, so the lens moves to the in-focus position by following the movement of the subject in the above-described operation. As described above, the switch SWI is kept on, steps (005) and (006) are repeated, and in the process of repeating the AF control subroutine, the low contrast judgment is made in the focus detection/judgment subroutine of each AF control subroutine. “Lens drive based on defocus amount when out of focus is detected” unless otherwise specified.
"Defocus amount detection and focus detection after lens driving, focus state detection judgment such as low contrast detection" is repeated, and in one-shot mode, after focus judgment is made by repeating the above ■■ operation, after the above ■■ The repeated operation is stopped, and the lens is held at the position where focus has been determined once. In addition, in the servo motor, the above operation ■■ continues to be repeated, and once the focus is determined, the subject moves and the out-of-focus determination is made, the lens performs the operation ■ and the focus is determined by the determination ■■. After that, this operation is repeated until the lens is moved to the in-focus position, following the subject. Next, a case will be described in which a search operation is performed (flag SRMV is 1) at low contrast (flag LCFLG is 1) in the "previous rAF control" subroutine. When the ``rAF control again'' subroutine is executed after the above search operation is performed, the state of the flag SRMV is detected in step (112), and the process moves to step (113). In step (113), information on the lens driving state is input from the lens, and if the lens has already stopped, step (113)
The process moves to step (19), and if driving is in progress, the process moves to step (114). As described in step (109) above, the control circuit LPR3 generates a lens stop signal when the lens is driven by the defocus amount, but when the lens is driven in the close-up direction or infinity direction due to the search operation, the control circuit LPR3 generates a lens stop signal when the lens is driven by the defocus amount. Focus amount information is not given. On the other hand, as mentioned above, if the lens hits the close position or the infinite end, the pulse from the encoder ENC will no longer be generated even though a lens drive command has been issued, and even if this condition occurs, the control circuit will A lens stop signal is formed in LPR5. Therefore, in step (113), this lens stop signal is detected in the same manner as in step (109) above, and steps (119) and (114) are branched. As mentioned above, the search operation is as follows: ■ Drive the lens in the closest direction (variable 5RCNT = 1
) ■ If a contrasting subject cannot be found during driving and the focusing lens reaches its mechanical limit on the close-up side,
This time, drive the lens towards infinity (variable 5RCNT=
2) If the focusing lens reaches its mechanical limit on the infinity side without finding a contrasting object during the drive of ■ ■,
This time, control is performed to drive the lens to the search start lens position (variable 5RCNT=3). If the lens is being driven, in step (114) "
Execute the "Focus Detection" subroutine. In this subroutine, the defocus amount and contrast of the subject are detected. Next, in step (115), the state of the low contrast flag LCFLG is determined, and if LCFLG is 1 and the contrast is low, the rAF control subroutine is returned in step (117). That is, in the search operation, focus detection is performed while the lens is being driven, and if the contrast is low in that state, nothing is done and the lens continues to be driven. Also, the flag LCFLG is set here during focus detection while driving the lens.
When it is determined that the contrast is not low because 0, the process moves to step (116), and a "drive stop command" is sent to the lens, LMR and LMF are set to °L°, and the drive of the lens is stopped. Next, in step (11B), the flag S
After clearing the RMV, new focus adjustment control is performed in step (129). That is, if the contrast is not low during focus detection during the search operation, that is, if the contrast is sufficient for focus detection, the lens is stopped and the search operation is ended (SRMV is set to O).
A new focus adjustment after the step (129) described above is performed, and the lens is moved to the in-focus position by the above-described operation. When the contrast cannot be detected while the lens is being driven toward the close-up direction in the operation (2) described above, the rA
Step (11) is executed every time the "F control subroutine" is executed.
7) Then, the rAF control J subroutine is returned. In the above operation, the lens continues to be driven in the close-up direction without sufficient contrast being detected, and when the lens reaches the close-up end, the lens stop is detected in step (113) and the process moves to step (119). . Since we are now talking about the case (2) above, the process moves to step (120). In addition, in the case of ■, the process moves from step (119) to step (123), and here step (124)
Move to. In case (2), the process moves to step (11B) to end the search operation.The case (2) will be described later. Now, in step (120), 1 is added to the variable 5RCNT. This is because the lens has reached the closest end, so the lens is driven in the infinite direction.
In the next step (121), an "infinite direction drive command" is sent to the lens, and in the same manner as the close-up drive, the drive command is transmitted to the lens and the lens is driven in the infinite direction, and the above search operation (2) is started. and rAF control in step (122).
Return subroutine. During operation (2), steps (113) and (115) are repeated until the lens reaches the infinite end, and if contrast cannot be obtained, control is performed using the "rAF control" subroutine as in the case (2) described above. Each time it is executed, the process returns to step (117), and if contrast is detected during driving to the infinite end, steps (116) and (118) are repeated as in ■.From that point on, the process described above is performed. In the operations after step (129), the lens moves to the in-focus position. Also, when the low contrast state is maintained through the operation of ■ and the focusing lens reaches its mechanical limit on the infinity side,
In step (113), the lens stop is detected and in step (1
The process proceeds to step (123) via step (19). Now, since the search operation is ■, S_RCNT is 2, and the process moves from step (123) to step (124). In step (124), 1 is added to the variable 5RCNT to create 5RC.
NT=3, which results in search operation (2). In step (125), the above-mentioned distance ring counter value FC is
Manually run NT and add LPO to variable FP in step (126)
3 = Store the value of FCNT. The variable LPos stores the value of the distance ring counter that represents the lens position when performing the search operation in steps (138) and (139).
In addition, FCNT in step (125) is the current counter value that represents the lens position at the time when the operation in ■ is completed, and FP, which is obtained by subtracting the current counter value from LP01, is the value from the current lens position to the search start position. It represents the distance ring counter value. In step (127), this FP is sent to the lens control drive circuit LPOS in the same way as in the above-mentioned communication, and a command is given to drive the lens by an amount equal to FP based on the distance ring counter value. Based on the FP, the circuit LPOS detects the amount of movement of the lens using a pulse from the encoder ENC in the same way as normal lens drive control based on the amount of defocus, and drives the lens by the above FP to drive the lens to the search start position. do. Then, in step (128), the "rAF control" subroutine is returned. Control during lens drive based on FP in search operation ■ is the same as in case ■■ described above, and if sufficient contrast is detected while approaching the search start position, the lens is stopped at that point. , thereafter, normal focus adjustment operation is started in steps after step (129). If it is not determined that the contrast is sufficient during the operation (2) and the focusing lens reaches the search start position, the lens stop is detected in step (113), and after steps (119) and (123), After clearing the flag SRMV and ending the search operation in step (118), a new focus adjustment operation is started in step (129) and thereafter. Next, the AF continuous shooting operation in which the switch SW2 is kept turned on when the AF mode is the servo mode will be described. In this case, as described above, the release flag RLS is set to 1 in the "rAF control" subroutine. Therefore, in the "rAF control" subroutine that is performed after exposure is performed in the release operation, step (105)
The state of the flag RLS is detected at step (
106). In step (106), all flags are cleared and all past states related to "AF control" are initialized, and in the next step (107), AF continuous shooting
After setting AF to 1, the process moves to step (129) and a focus adjustment operation is performed. During AF quick shooting, flags PRMV and SRM related to lens drive and search operation are
The reason for the force that does not determine the state of V, and A
Regarding lens drive specific to F speed shooting, see "Lens drive"
Details will be explained in the subroutine. To summarize the flow of the rAF control subroutine described above, when the rAF control subroutine is executed from the camera's main routine, focus detection is performed, and if the result is not low contrast, the lens is driven based on the defocus amount. A new focus adjustment operation is not performed until the lens has been driven by a predetermined amount. In the case of low contrast, the search operation is started, the lens is first driven in the closest direction, focus detection is performed while the lens is being driven, and if a contrasting object is detected, the lens drive is stopped and the lens is moved in the stopped state. Perform the focus adjustment operation again. When the lens reaches the close end without being able to detect contrast, it is driven in the infinity direction, and when it reaches the infinity end, it is driven to the search start position. If contrast is detected during this time, the lens is stopped and a new focus adjustment operation is performed, and when the lens reaches the search position without contrast being detected, the search operation is ended there. FIG. 4(C) shows a flowchart of the "focus detection" subroutine. In step (202), the "great human power signal" subroutine is executed, and the image signal from the sensor device SNS is stored in a predetermined area within the microcomputer. A flowchart of the "image signal manual input" subroutine is shown in FIG. 4(d), which will be described later. Next, in step (203), the defocus amount DEF and contrast ZD of the photographing lens are calculated from the already stored image signals. The specific method is disclosed in Japanese Patent Application No. 61-160824 by the present applicant, so detailed explanation will be omitted. In step (204), three flags JFFLG, CH
Cleared 3FLG and LCFLG. Step (2
05), the contrast amount ZD and the predetermined amount LCLV
Compare L, and if ZD<LCLVL, step (206
) and sets the flag LCFLG to 1. That is, if the contrast amount ZD is smaller than the predetermined amount LCLVL, the low contrast flag LCFLG is set to 1. Then, in step (208), the focus detection J subroutine is returned. In step (205), Z
If D≧LCLVL, move to step (207),
Compare the absolute value of the defocus amount DEF and the predetermined amount CH3FLD, and if l DEF l>CHSFLD, step (
208) to return to the "focus detection" subroutine. In step (207) l DEF l≦CH3F
If it is LD, flag CH3 is set in step (209).
Set FLG to 1. That is, if the contrast is sufficient and the defocus amount is within the near-focus range expressed by C1 (SFLD), the near-focus flag CHSFLG is set to 1.
Set to . Next, in step (210) l DEF l and a predetermined amount JFFLD (JFFLD<CHSFLD) are compared, and if IDEF l>JFSFLD, step (2
11) and returns to the “focus detection” subroutine, and if l DEF l≦JFSFLD, step (2
After setting the flag JFFLG to 1 at step 12), the "focus detection" subroutine is returned at step (213). That is, if the defocus amount is within the focus range represented by JFFLD, the focus range flag JFFLG is set to 1. As mentioned above, in the focus detection j subroutine, the defocus amount and contrast of the photographic lens are detected, and if the contrast is low, the low contrast flag LCFLG is set to 1, and if the contrast is sufficient, it is cleared to 0. If the amount is near the focus, flag CH3FLG
If it is in the in-focus area, flag JFFLG is set to 1 and the process returns. FIG. 4(d) shows a flowchart of the ``Image Signal Manual j'' subroutine. When the ``Image Signal Human Power'' subroutine is executed, the state of the AF continuous shooting flutter FAF is determined in step (302). For example, in step (304), the predetermined value MXrTF is stored in the variable MAXINT, and if it is 0, the predetermined value MXITN is stored in the variable MAXINT in step (303).
k: Store. MAX I NT is a variable that specifies the maximum accumulation time of the sensor in units of 1 millimeter, and MXITN
>MXITF+7). Therefore, the maximum accumulation time is set short for the AF continuous shooting time. In the next step (305), the sensor device SNS is caused to start accumulating optical images. At the moment, the microcomputer PR3 sends an "accumulation start command" to the sensor drive circuit SDR, and the SDR sets the clear signal CLR of the photoelectric conversion element section of the sensor device SNS to °L' to start accumulating electricity. . In step (306), an accumulation time counter INTCNT set on the RAM is initialized to zero. In step (307), the 1 millisecond clock timer is reset and the clock operation is started from the reset state. Note that this 1 millisecond clock timer utilizes the timer function of the microcomputer PR3. In step (308), the state of the manual input terminal of PR3 is detected, and it is determined whether or not storage has been completed. The sensor drive circuit SDR outputs a signal INTEN at the same time as the start of accumulation.
Set D to °L°, monitor the AGC signal from SNS, and when 5AGC reaches a predetermined level, signal INTEND
is set to °H°, and at the same time the charge transfer signal SH is set to °H for a predetermined time.
INTEND at step (30B), which has a structure that transfers the charge of the photoelectric conversion element section to the CCD section.
If the terminal is "°H", it means that the accumulation has been completed and the process moves to step (313); if it is "Lo", it means that the accumulation has not finished yet and the process moves to step (309). If it has not been completed, it is first checked in step (309) whether the reset 1 millisecond timer has counted 1 millisecond. If 1 millisecond has not elapsed, the iJ step (3
08) and waits for the completion of accumulation or the elapse of 1 millisecond. If 1 millisecond elapses before the completion of accumulation, the process moves to step (310).
). At step (31°), the accumulation time counter INTCNT is counted up by one, and at step (31°), the accumulation time counter INTCNT is counted up by one.
Proceed to step 11), step (311) is the counter I N
TCNT and the variable MAX rNT are compared, but MA
As mentioned above, XINT is the longest accumulation time expressed in units of 1 millisecond, and if TNTCNT is less than MAXI N7, the process returns to step (307) and waits for the accumulation to end again. When MAX I NT matches MAX I NT, the process moves to step (312) and the accumulation is forcibly terminated. The forced storage termination is executed by sending an "accumulation termination command" from the microcomputer PR3 to the sensor drive circuit SDR. When the "accumulation end command" is sent from PR3, the SDR sets the charge transfer signal SH to 'H' for a predetermined period of time to transfer the charges in the photoelectric conversion section to the CCD section. The sensor accumulation ends in the flow up to step (312). That is, the above steps (305) to (311
), if the accumulation is completed within the maximum time MAX I NT from the start of accumulation, at that point step (313
), and if the accumulation does not end within the above time,
When this time has elapsed, the storage operation is forced to end and the process moves to step (313). In step (313), the image signal O3 of the sensor device SNS is
A/D of signal AO3 amplified by sensor drive circuit SDR
Performs conversion and stores the digital signal in RAM. To explain in more detail, the SDR generates the CCD driving clocks φ1 and φ2 in synchronization with the clock CK from PR3 and supplies them to the control circuit 5SCNT inside the SNS, and the SNS generates the CCD driving clocks φ1 and φ2. The charge in the CCD is output as an image signal in time series from the output O3. After this signal is amplified by an amplifier inside the SDR, it is input as an AOS to the analog input terminal of the PRS. The PRS performs A/D conversion in synchronization with the clock CK that it outputs, and sequentially stores the digital image signal after A/D conversion in a predetermined address of the RAM. Step (314)
Return to the "image signal human power" subroutine. FIG. 4(e) shows a flowchart of the "judgment" subroutine. In step (402), three flags JF, AFNG,
Clear LMVDI. JF is a flag indicating the in-focus state, AFNG is a flag indicating that focus detection is impossible, and LMVDI is a flag prohibiting lens driving. In step (403), the state of the focus area flag JFFLG that is set in the "focus detection" subroutine is determined, and if it is 1, it is determined that the focus is in focus, and the process moves to step (404) to control the focus state. In step (404), both the focus flag JF and the lens drive inhibition flag LMVI:l are set to 1. Next, in step (405), the constant 5RCNT is cleared. As mentioned above, 5RCNT=
0 means that no search operation is being performed. That is, when the object is in focus, the result is the same as when no search operation is performed, and when the contrast becomes low, the search operation is performed again. Subsequently, in step (406), the flag T
Set MACT to 1. TMACT will be described later. This flag indicates that the lens drive regulation timer is in operation. In step (407), the timer is started, and in step (408), the "judgment" subroutine is returned. The lens drive regulation timer is a timer that utilizes the internal timer of the microcomputer PR3, and starts counting from the time it is restarted, and its contents can be read at will. If the focus area flag JFFLG is O in step (403), the process moves to step (409), and the low contrast flag LCF set in the "focus detection" subroutine is
The status of LG is determined. If the flag LCFLG is 1 in step (409), it is assumed that the focus detection result is low contrast, and the process goes to step (410) for nine lines. In step (410), the search operation state variable 5RCNT
The state is detected, and if it is not 0, the process moves to step (411). The fact that variable 5RCNT is not O means that
This indicates that a search operation has been performed since the switch SWI was turned on, and in this case, the focus detection failure flag AFN is set in step (411) to prevent the search operation from being performed again
G is set to 1, and the lens drive prohibition flag LMVDI is set to 1 in the next step (412). flag LM
If VDI is 1, step (133) is executed in step (132) of the "rAF control" subroutine in FIG.
) and return to rAF control, the search operation after step (138) is not performed. If the variable 5RCNT is O in step (410), the process moves to step (414), and the continuous shooting AF flag FAF
Detects the state of To step (414), flag FAF is 1, that is, quick shooting AF
If so, proceed to step (412) and set the flag LMVDI.
is set to 1 to disable the search operation. When the slug FAF is O, the process moves to step (415), and in this case, the operation is performed in the "rAF control" subroutine. That is, the above search operation is executed when it is determined that the contrast is low in the "focus detection" subroutine at step (129) in the AF control subroutine and the flag LCFLG is set to 1, but the search operation is executed when the flag LCFLG is set to 1 in the "focus detection" subroutine at step (129) in the AF control subroutine. ), when the flag LMVDI is detected as 1, the process does not proceed to the search operation after step (13B);
Even if it is determined in step (129) that the contrast is low, no search operation is performed. In addition, even if it is determined that the contrast is low in the "focus detection" subroutine of step (129) in the determination subroutine, if it is determined that 5RCNT≠0 in step (410), and even if 5RCNT=O, step (412) is executed. When it is determined that it is AF quick shooting, the flag LMVDI is set to 1 in step (412), and under such a situation, no search operation is performed even if low contrast is determined in step (129). Furthermore, if a search operation has been performed previously, 5RCNT≠0, so even if a search operation has been performed previously and the subsequent execution of the rAF control subroutine determines that the contrast is low, the step Regarding (132), move to (133) and return to the AF open control subroutine. Therefore, the above search operation will be performed only once. Also, as described above, the focus judgment is made in the judgment subroutine. and 5RCNT=O. Therefore, if it is determined that the contrast is low in step (129) during the execution of the subsequent "rAF control" subroutine, a search operation is executed even if a search operation has been performed previously. Also, during AF rapid shooting, the search operation will not be performed even if low contrast is determined in step (129), preventing the search operation from being performed during AF continuous shooting and missing a photo opportunity. are doing. Therefore, the search operation is performed when the contrast is determined to be low when AF is not a quick shot, and even if the contrast is determined to be low again in the subsequent AF control subroutine, the search operation is performed once and then the focus is determined once. If not, it will not be executed and will be permitted subject to focus determination. Further, if the low contrast flag LCFLG is 0 in step (409) of the determination subroutine, that is, the contrast is sufficient, the process moves to step (415). In step (426), the continuous shooting AF flag FAF is determined. Here, if the flag FAF is 1 and it is a continuous shooting AF state, the process moves to step (412); otherwise, the process moves to step (417). That is, if the focus state is not near the in-focus state and it is a quick shooting AF state, step (412
), lens driving based on the amount of defocus at this time is prohibited. That is, in quick-shooting AF, driving of the Gobo lens is prohibited under low contrast, and even if there is sufficient contrast, lens driving is prohibited when defocus is large, and a small defocus judgment is made.
The lens is driven only when the lens drive time (until focusing) is short. Therefore, the release interval in quick shooting is shortened, providing a state suitable for continuous shooting mode. In step (417), the state of the lens drive parent control timer operation flag TMACT is determined, and if it is 0 and inactive, the process moves to step (418) and returns to the "determination" subroutine. If TMACT is 1 and is in operation, the process moves to step (419) and the subsequent lens drive regulation timer is controlled. In step (419), the state of the low contrast flag LCFLG is determined, and if it is 1, step (419) is performed.
12) and set the predetermined constant WTTMLC to the variable TMLNG.
Store. If the flag LCFLG is O, the process moves to step (420), and a predetermined constant WTTM is stored in the variable TMLNG. TMLNG is a variable that defines the operating time of the lens drive regulation timer, and the constants have a relationship of WTTM<WTTMLC. If the lens drive regulation timer that starts counting when the lens is in focus is less than the above TMLNG, lens drive based on the defocus amount is prohibited, and if TMLNG is exceeded, lens drive is permitted, so the focus detection result When the contrast is low, the time from focusing to performing the search operation is longer than the time from starting lens drive when the contrast is not low. In step (422), the value of the lens drive regulation timer being measured is compared with the variable TMLNG, and if the former is larger, the process moves to step (424), the lens drive regulation timer operation flag TMACT is cleared, and step (424)
Returns the "judgment" subroutine. Step (4
22), if the latter is larger, step (423
) and set the lens drive prohibition flag to 1.
In step (425), the "judgment" subroutine is returned. In the above steps (415) to (426), when a small defocus is detected during AF quick shooting as described above, the lens is immediately driven, and at other times, Gobo lens drive is prohibited. In addition, in the case of AF quick shooting, the lens is driven immediately when a small defocus amount is detected, and when a small defocus amount is detected, if focus has never been detected before, or after focus is detected, the WT
The lens is driven immediately when the TM time has elapsed, and even if a large defocus is detected, the WTTM is activated after the focus is detected.
Lens driving is prohibited during this time, and if large defocus is detected even after this time has elapsed, the lens is driven for the first time. In addition, in the search operation described above, if focus has not been detected before, lens drive is performed immediately, and in a search operation after focus detection has been performed previously, after focus, the lens is driven Lens driving is prohibited until the long WTTMLC time has elapsed. Therefore, even if the lens is removed from the subject due to camera shake etc. after focus detection and the contrast becomes low, if the lens is returned to the subject within the above time after focus, the search operation will not be performed. It is possible to prevent disadvantages such as missing a shirt turn due to unnecessary search operations. Also, the reason for prohibiting lens drive within the timer time after focusing even when detecting a large defocus amount is the same as above, and in this case, the timer time is shorter than the search operation because the search operation This is because when executed, the lens is driven for a longer time than when detecting a large defocus, so the travel conditions for the search are made more severe. The reason why the lens is immediately driven at the time of large and small defocus is that there is usually a slight change, and a small amount of defocus is detected during normal focusing. Therefore, in the servo mode, it is necessary to follow this change. Further, the post-focus defocus amount may be detected when the lens is removed from the subject due to camera shake or the like as described above. Therefore, as mentioned above, lens driving is prohibited during the timer period. Similarly, search operation is prohibited during snapshot AF, so
In this case, LMVDI is also set to 1. Therefore, when the search operation is not a quick-shot AF, and a low contrast determination is made without previously determining focus in the process of repeating the AF control subroutine,
・After the one-turn-ch operation is performed, a focus determination is made thereafter, and this is then executed when a low contrast determination is made. In addition, in the above-described repeated focus detection judgment operation and lens drive, if the detected defocus amount is less than a predetermined value, the lens is immediately driven, but if the detected defocus amount is greater than a predetermined value, the lens is previously focused and the lens drive is regulated. When the timer is in operation, that is, when a certain period of time has not elapsed since focusing, the lens is driven after waiting for this period of time to elapse. Further, in the case of lens driving during a search operation, the lens is driven only after a certain period of time, which is longer than the certain period of time after focusing, has elapsed. The "judgment" subroutine and overall flow described above can be summarized as follows. When the switch SWI is turned on and the AE control subroutine and AF control subroutine are repeated, if the focus detection result indicates that the defocus amount is below the in-focus range, the lens is driven based on the defocus amount, and the lens is driven based on the defocus amount. After the lens driving based on the focus amount is completed, the focus detection/determination operation is performed again. If focus is not determined in this state, lens drive and focus detection/determination based on the detected defocus amount are performed again until focus is determined, and when focus is determined, the focus flag JF is set to 1. and set the lens drive prohibition flag LMVDI to 1. At the same time, the lens drive regulation timer is activated. If the one-shot mode is set in this state, focus detection/judgment and lens driving will not be performed in the subsequent AF control subroutine, and the lens will be held in the state once it is in focus. In addition, in servo mode, the focus detection/judgment and lens drive operations described above are executed every time the AF control subroutine is performed even after focusing, and the lens always follows the movement of the subject.
Move to focus state. When the AF control subroutine determines that the contrast is low, the search operation described above is executed. LMVD to prevent search operation even if
Set I to 1. Further, as for the image signal accumulation time in the focus detection operation, the maximum accumulation time is set short in the case of quick-shooting AF in accordance with normal AF, the AF operation time is made as short as possible, and the shutter release operation interval is shortened. Further, in the case of AF quick photography, lens driving is permitted only when contrast is sufficient and a small amount of defocus is detected. FIG. 4(f) shows a flowchart of the "lens drive" subroutine. When this subroutine is executed, step (502)
communicates with the lens at
Input TI (J. "S" is the coefficient j of the amount of defocus versus the amount of extension of the focusing lens, which is unique to the taking lens. For example, in the case of a single lens that extends entirely, the entire taking lens is used for focus adjustment. Since it is a lens, S = 1, and in the case of a zoom lens, S changes depending on each zoom position. rPTHJ is the focus adjustment per output pulse of the encoder ENC linked to the drive of the focus adjustment lens LNS in the optical axis direction. This is the amount of lens extension.These data are stored in the memory in circuit LPR3, and are input to the computer through communication between the computer and circuit LPRS.Therefore, the current amount of defocus of the photographic lens The value obtained by converting the amount of extension of the focusing lens into the number of output pulses of the encoder using DEF, S, and PTH described above, the so-called lens drive amount FP, is given by the following formula: FP=DEFXS/PTH Step (503) is shown above. The formula is executed as is. In step (504), F obtained in step (503) is
Sends P to the lens to command the driving of the focusing lens (or the entire photographic lens in the case of a fully extending single lens),
In the next step (505), the "lens drive" subroutine is returned. [Effects of the Invention] As explained above, according to the present invention, when the focus detection result is in focus or near focus, the lens is immediately driven if the subsequent defocus amount is within a predetermined amount, and In some cases, lens driving is prohibited within a first predetermined time period from the time when the subject is in focus or near focus; The search operation is prohibited during the predetermined period of time, which enables focus adjustment with improved operability, especially when a telephoto lens is attached. 4. Brief explanation of the drawings Fig. 1 is a diagram of the optical principle of the focus detection device of the present invention, Fig. 2 is a waveform diagram showing the output state of the sensors SAA and SAB of Fig. 1, and Fig. 3 is a diagram showing the output state of the sensors SAA and SAB of the present invention. A circuit configuration diagram showing one embodiment of the camera used, and FIGS. 4(a) to 4(f) are explanatory diagrams showing a program for explaining the operation of the camera using the present invention.

Claims (2)

[Claims] (1) The light flux from the subject that has passed through the photographic lens is received by a plurality of photoelectric conversion element arrays, and the output of the photoelectric conversion element array is used to detect the defocus amount of the photographic lens and the detected defocus amount. If the reliability is high, a first lens drive is performed to drive the photographing lens based on the detected defocus amount, and if the reliability is low, the detected defocus amount is determined. performing a second lens drive that drives the photographing lens regardless of the
In a camera focus adjustment device, when the reliability is high and the detected defocus amount is smaller than the predetermined amount, the first lens is driven immediately; If the reliability is large, driving of the first lens is prohibited within a first predetermined time period from the time when the focus adjustment device detects that the focus state of the photographing lens is in focus or near focus, and the reliability is improved. A focus adjustment device for a camera, characterized in that when the temperature is low, driving of the second lens is prohibited within a second predetermined time period from the time point. (2) The camera focus adjustment device according to claim (1), wherein the first predetermined time is shorter than the second predetermined time.