JPS63172234A - Auto-focusing device - Google Patents

Abstract

PURPOSE:To improve the operability of the titled device in a continuous photographing state by restricting a lens driving time for the focusing operation of each photographing when a camera is in the continuous photographing state. CONSTITUTION:If a defocused value of an object is increased when the succeeding photographing operation is inhibited until lens driving based upon a focused state is completely ended during the focusing operation in the continuous photographing state, the photographing of the succeeding frame is delayed by the expanded time of lens driving. Thereby, a microcomputer PRS restricts the lens driving time in the focusing operation (input of object image, processing of a focus detecting signal and lens driving) of each photographing in the continuous photographing state of the camera. Consequently, the focusing operation improving the operability in the continuous photographing state 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.

Furthermore, the original usage of the camera is in what is called "continuous shooting," where the external motor drive or built-in winder is used to wind the film and take pictures continuously. A method is used in which the above-mentioned focus adjustment operation is performed every time the film is wound.

However, if the focus adjustment operation in the above-mentioned continuous shooting state is such that the next shooting operation is not performed until the lens drive based on the focus state is completely completed, the amount of defocus of the subject becomes large (as a result, the lens The drive time is long (as a result, there is a delay in taking the next frame, which is extremely inconvenient considering that continuous shooting is often used to track a moving subject). Met.

[Purpose of the invention]

The present invention aims to solve the above-mentioned problems, and its gist is that when the camera is in the above-mentioned quick shooting state, the lens is driven during the focus adjustment operation (subject image input, focus detection signal processing, lens drive) for each shooting. By limiting the time, it is possible to perform focus adjustment that improves operability during quick shooting.

〔Example〕

First, the principle of focus detection in the present invention will be explained using FIG. Photographing lens L N whose focus should be detected
A field lens FLD is arranged on the same optical axis as S. Behind it, two secondary continuous image lenses FCLA and FCLB are arranged symmetrically 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 image lenses FCLA and FCLB.
An IB will be provided. The field lens FLD connects the exit pupil of the photographic lens LNS with two secondary continuous image lenses FCLA and F.
The image is almost formed on the pupil plane of CLB. As a result, the ray bundles incident on the secondary imaging lenses FCLA and FCLB are placed on the exit pupil plane of the photographing lens LNS at each secondary imaging lens F.
They are emitted from areas of equal area that do not overlap with each other and correspond to CLA and FCLB. Aerial images formed in the vicinity of the field lens FLD form secondary imaging lenses FCLA, FCLB1. :, more sensor arrays SAA, S
When the image is re-formed on the surface of AB, the two images on the sensor arrays SAA and SAB will change their positions 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 L
The focal state of the NS 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),
The output of SAB is B(1), and in this example, the number of pixels of the sensor is 40 (i = O, . . . , 39).

A signal processing method for detecting the image shift amount PR from image signals A (i) and B (i) is disclosed in Japanese Patent Application Laid-Open No. 58-142306.
No. 1, JP-A-59-107313, JP-A-Sho 60
-101513 Publication or Japanese Patent Application No. 1608-1983
No. 24, etc. have been disclosed by the present applicant.

By adjusting the focus of the photographic lens based on the image deviation obtained using the method started 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, the control device of the PRS camera includes, for example, a CPU (central processing unit), ROM, and RAM.

EEPROM (Electrically Erasable Programmable RO)
M), A one-chip microcomputer with A/D conversion function, which controls the camera's automatic exposure control function, automatic focus detection function, film winding/rewinding, etc. according to the camera's sequence program stored in the ROM. is performing the following actions. EEPROM is a type of nonvolatile memory, and various adjustment data are written in the process.

PH1 communicates with peripheral circuits and lenses using communication signals So, SI, and 5CLK, and controls the operation of each circuit and lens.

SO is the data signal output from PH1, SI is PH1
The data signal input to SCLK is the signal so,
This is the sr synchronization signal.

LCM is a lens communication buffer circuit, which applies lens power VL to the lens when the camera is in operation, and serves as a buffer for communication between the camera and the lens when the signal CLCM from PH1 is at a high potential level.

PH1; 6 (CLCM is set to H'+: 5CLKI: When predetermined data is sent from So in synchronization, LCM transmits buffer signals LCK, - of 5CLK and So through the camera-lens interface. Output DCL to the lens.

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', and
, Sl, is controlled from PH1 using 5CLK.

The signal CK is a clock for generating CCD driving clocks φl and φ2, and the 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
5 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 a sensor power for AGC control within the SNS, and is input to the SDR, and a series of operations of the SDR used for storage control of the SNS 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 signal CDDR is L' and SO.

Controlled from PH1 using Sl, 5CT-K. That is, based on the data sent from PF3, the display of the camera's display member DSP is 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 etc. PH
Contact 1.

MDRI and MDR2 are drive circuits for the film feeding and shutter spring winding motors MTRI and MTR2, and the signals MIF, MIR, M2F, and M2R control the normal rotation and rotation of the motors.
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. Amplifying transistors TRI and TR2 are energized, and shutter control is performed by PF3.

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

A signal DCL input to the intra-lens control circuit LPR3 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.

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, which is simultaneously sent (according to the drive amount and direction). .

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.
It is monitored by pulse signal 5ENC of C and counted by a counter in LPR3, and when a predetermined movement is completed, signals LMF and LMR are set to L' to brake 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. still,
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 PF3 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), the control flag set in the RAM in PR8 is cleared. The above steps (002), (003), and (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, when SWI is turned on, the lens is The drive will be stopped. When the SWI is turned on, the process moves to step (005). Step (005) is “
It means the subroutine of AE sub-control. This rAE
The "Control" subroutine performs a series of camera operation controls such as photometric calculation processing, exposure control, shutter charging after exposure, and film winding.

Note that the "rAE 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 AE sub-control subroutine is executed, and the photometry and exposure control calculation 9 display is performed each time.When the switch SW2 is turned on by the second stroke of the release button (not shown), the microcomputer DR8
The release operation is started by the interrupt processing function of the camera, and the aperture or shutter speed is controlled based on the exposure amount determined by the above exposure control calculation, and after the exposure is completed, shutter charging 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 AF modes, so-called "one shot" and "servo". 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 camera 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 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. Servo selection is made by a mode selection switch (not shown).

As mentioned earlier, the release operation is performed by turning on switch SW2, but if SW2 is left on even after one frame of film has been shot, the AE sub-control will be returned as having been terminated. do.

Therefore, to explain the operation with SW2 turned on,
In the case of a one-shot, the release cannot be released until focus is achieved. Once the focus is achieved, the release is possible and one frame is taken. After that, the focus is not adjusted as it is a one-shot, and the next frame is taken with the same lens position. Photographing is performed, and photographing continues as long as the switch SW2 is on.

In the case of a servo, it is possible to release the release at any time, 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 photography is performed, and as long as SW2 is on, "Release operation", "AF sub control", "Release operation J
``AF sub-control will be repeated alternately. We will call this situation rAF continuous shooting.''
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.

Now, as mentioned above, in step (005) r
When the “AE control” subroutine ends, step (00
6) "AF sub-control subroutine is executed.

FIG. 4(b) shows a flowchart of the "rAF control" subroutine. First, in step (102), the AF mote 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, the process moves to step (103) and the state of the flag JF is detected. As will be described later, JF is a flag that is set in the "judgment" subroutine in step (130) and represents the focus state. Checking flag JF in step (103) means checking the previous focus state. means. Here, if the flag is JF Rikitsu, it means that it was in focus last time, so the process moves to step (104) and returns to the ``rAF control'' subroutine. That is, in one-shot mode, once the focus is focused, the switch s
No new AF sub-control will be performed until flag 1 is turned off and all flags are cleared in step (004). During the first rAF control after turning on the switch SWI, the flag JF 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. In step (105), the flag RL
If S is set to 1, it is recognized that it is immediately after release in servo mode, that is, rAF continuous shooting, and the process moves to step (106).

rAF continuous shooting", first clear all flags in step (106), 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 interrupt processing to transition to the release operation routine at any step in the program. Step (1)
06), all flags are cleared. F.A.F.
is a flag that recognizes "rapid shooting AFJ" in the "rAF control" subroutine.

In step (105), the flag RL_S. If so, proceed to step (108).

In step (108), 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 after the switch SWI is turned on, the flag PRMV is 0, and the process moves to step (112).

In step (112), the state of the flag SRMV is detected, but SRMV is also a flag related to lens control, and since SRMV=0, 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 focus is in focus or the focus cannot be detected based on the result of the "focus detection" subroutine, and if lens drive is not necessary, the lens drive prohibition flag LMVDI is set to 1.
Set to .

Next, in 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, if lens drive is not required, LMVDI is set to 1, so step (13
If LMVDI=1 in 2), step (133)
Then, the subroutine ``rAF control'' is returned.

If the flag LMVDI is O, the process moves to step (134) and 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. If LCFLG is 0 in step (134,), it means that the contrast is sufficient for focus detection, and in step (135,)
After performing "lens drive", the lens drive flag PRMV is set to 1 in step (136), and step (13
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 Stella (138), the count value FO 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.
Input NT from the in-lens control device L P RS. This counter is reset to O when the lens power supply VL starts supplying power, and the feeding direction is determined to be up count 1-1 and the feeding direction is determined to be down counting.

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
This count value represents the relative position of the lens when the search operation is started, and as will be described later, the contrast is changed by the search operation. This is used to return the lens to this search starting lens position when a sufficient number of objects cannot be detected.

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 if the focusing lens is at its mechanical limit at the closest end (if
PRS detects this and the lens itself stops driving. Note that the mechanical limit position is detected using encoder pulse 5.
It is recognized by the time interval of ENC. Step (14,
1) Set variable 5RCNT and flag SRMV to 1.

5RCNT is a variable that represents the state of the search operation; 0 when the search operation is not being performed, 1 when the lens is being driven in the close direction, 2 when the lens is being driven in the infinite direction, and 2 when the lens is being driven toward the search start lens position. It is set to 3 when it is running. Now, after driving the lens in the close-up direction, the variable 5RCNT is set to l. Further, SRMV is a flag indicating that the search operation has performed lens driving.

In steps (138) to (14], ), initial control of the sensor operation is performed, and in step (14, 2), the "rAF control" subroutine is returned.

In FIG. 4(a), when the AF sub-control subroutine in step (006) is completed, the state of the switch SWI is determined again in step (002).
If it 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 1AF control subroutine, lens drive is stopped when the switch SWI is turned off. Then, in the next step (004), all flags are cleared.

If the switch SWl remains on in step (002), execution of the ``AF sub-control subroutine'' in step (005) and then rAF control again in step (006) is started.

The flow of the "1AF control while switch SWI is on" subroutine will be explained below in different cases.

First, a case will be described in which the contrast is not low (the flag LCFLG is O) and the lens is driven (the flag PRMV is 1) in the "past rAF control" subroutine.

"When the AF sub-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 drive state is input from the lens control circuit LPR8 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
Returns the AF sub-control subroutine. That is, a new focus adjustment operation will not be performed until the lens has been driven by the amount instructed in the previous AF sub-control step (135).

Next, a case will be described in which a search operation was performed (flag SRMV months) with low contrast (flag LCFLG is 1) in the previous l'-AF sub-control subroutine.

When the "JAF 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 it is being driven, the process moves to step (]]4). 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 the focusing lens reaches its mechanical limit on the infinity side without finding a contrasting subject while driving ■■, 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 defocus amount and contrast of the subject. Next, in step (115), the state of the low contrast flag L CF L G is determined, and the L CF L
If G is 1 and the contrast is low, in step (117)
Returns the AF sub-control subroutine. That is, when focus detection is performed in a search operation, nothing is done if the contrast is low. Here flag L D F
When it is determined that LG is O and the contrast is not low, the process moves to step (116), and a "drive stop command" is sent to the lens. Next, after clearing the flag SRMV in step (11B), new focus adjustment control is performed in step (129). That is, if focus detection during the search operation is not low contrast, that is, if enough contrast is detected for focus detection, the lens is stopped and the search operation is ended (SRMV is set to 0).
Then, new focus adjustment is performed.

If the contrast cannot be detected by the above-mentioned operation (■), the ``rAF control'' subroutine is returned in step (117) every time the AF sub-control subroutine is executed until the focusing lens reaches its mechanical limit on the close side. I will do it.

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 (I ]
, 9) to step (123), and then to step (124). In case (2), the process moves to step (118) and the search operation ends, but 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 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 (1, 22) rA
The "F control" subroutine is returned. The control when contrast cannot be obtained even during the operation of ① is the same as in the case of ③ described above (, rAF control'' every time the subroutine is executed, it returns at 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 step (119). Since the search operation is now ■, 5RCNT is 2, and the process moves from step (123) to step (124).

In step (+24), 1 is added to the variable 5RCNT, and from this point on, the search operation (2) is performed.

In step (125), the above-mentioned distance ring counter value FC is
Input NT and set LPO to variable FP at step (+26)
Store the value of I-FCNT. The variable LPOS 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 this, represents the distance ring counter value from the current lens position to the search start position. There is. 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 (] 1.3), and step () is started.
119), (123), step (118)
After clearing the flag SRMV and ending the search operation, a new focus adjustment operation is started from step (129) onwards.

Next, we will describe the operation of AF continuous shooting in which the AF mode is the search mode and the switch SW2 is kept on.

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

In the l'-AF sub-control subroutine, step (10
In step 5), the state of the flag RLS is detected, and the process moves to step (106). In step (106), all flags are cleared and all states related to "past rAF control" are initialized, and in the next step (107), AF continuous shooting fluff FAF is set to 1, and then the process moves to step (129). to perform the focus adjustment operation.

During AF continuous shooting, the status of flags PRMV and SRMV related to lens drive and search operations is not determined. Explain in detail.

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 input" 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 1DEF 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. 160824/1983 by the present applicant, so detailed explanation will be omitted.

In step (204), three flags JFFLG.

Cleared CH3FLG and LCFLG. In step (205), the contrast fiZD and the predetermined amount L
Compare CLVL, and if ZD<LCLVL, step (
206) and sets the flag LCFLG to 1. That is, if the contrast iZD is smaller than the predetermined amount LCLVL, the low contrast flag LCFLG is set to 1. Then, in step (208), the "focus detection" subroutine is returned.

If ZD≧LCLVL in step (205), the process moves to step (207), where the absolute value of defocus amount DEF and the predetermined amount CH5FLD are compared, and IDEFl>CH
If it is 3FLD, the process moves to step (208) and returns to the "focus detection" subroutine.

In step (207) l DEF 1≦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 CH3FLD, the near-focus flag CH8FLG is set to 1.

Next, in step (210), IDEFl and a predetermined amount of JFFLD are compared, and l DEFl > JFFLD.
If so, proceed to step (211) and return to the "focus detection" subroutine, and if lDEF l≦JFFLD, set the flag JFFLG to 1 in step ('212), and then proceed to step (213) to return to the "focus detection" subroutine. ”Return subroutine. That is, the amount of defocus is J
If it is within the focus range represented by FFLD, a focus range flag JFFLG is set to 1.

As described above, in the "focus detection" subroutine, the defocus amount and contrast of the photographic lens are detected, and the low contrast is set to 1, and if the contrast is sufficient, it is cleared to O. Furthermore, if the defocus amount is near the focus, flag C
H S F L G, if in focus area, flag JFFL
Set G to 1 and return.

FIG. 4(d) shows a flowchart 1 of the "image signal input" subroutine. When the "image signal input" subroutine is executed, in step (302), the AF continuous shooting
Determine the AF status, and if FAF is 1, step (3
04), the predetermined value MXTTF is stored in the variable MAXINT, and if it is 0, the predetermined value MXTTF is stored in the variable MAXINT in step (303).
is stored in MAXINTR. MAXINT is a variable that defines the maximum accumulation time of the sensor in units of 1 millisecond, and has the relationship MXITN>MXITF. Therefore, during AF quick shooting, the maximum accumulation time is set short.

Next, in step (305), the sensor device SNS is caused to start accumulating optical images. Specifically, microcomputer PR
S sends an "accumulation start command" to the sensor drive circuit SDR, and SDR sets the clear signal C L R 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 PRS.

In step (308), the state of the input INTEND terminal of the PRS is detected and it is determined whether or not accumulation has been completed. The sensor drive circuit SDR outputs the signal INTEND at the same time as the start of accumulation.
is set to L', the AGC signal SAGC from SNS is monitored, and when SAGC reaches a predetermined level, the signal INTE is set to L'.
ND is set to H'', and at the same time the charge transfer signal SH is set for a predetermined period of time.
It has a structure in which the charge in the photoelectric conversion element section is transferred to the CCD section when set to H'.

If the INTEND terminal is H° in step (308),
Since the accumulation has finished, the process moves to step (313), and if the result is L'', it means that the accumulation has not finished yet, and the process moves to step (309).If it has not finished,
In step (309), it is checked whether the 1 millisecond timer reset earlier has counted 1 millisecond. If 1 millisecond has not elapsed, the process moves to step (308) and waits for the accumulation to end or for 1 millisecond to elapse.

If 1 millisecond elapses before the accumulation ends, the process moves to step (310). In step (310), the accumulation time counter IN
Count up TCNT by 1, step (311)
Proceed to. In step (311), the counter INTCNT
As mentioned above, MAXINT is the longest accumulation time expressed in units of 1 millisecond, and if INTCNT is less than MAXINT, the process returns to step (307) and waits for the accumulation to end again. IN
When TCNT matches MAXINT, step (312
) and force the accumulation to end. Forced accumulation is terminated by the sensor drive circuit SDR from the microcomputer PRS.
This is executed by sending an "accumulation end command" to.

When the SDR receives the "accumulation end command" from the PRS, it sets the charge transfer signal SH to "H" for a predetermined period of time and transfers the charge in the photoelectric conversion section to the CCD section.The flow up to step (312) completes the accumulation in the sensor. It will end.

In step (313), the image signal OS of the sensor device SNS is
A/D of signal AOS 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 the PRS and provides them to the control circuit SSCNT inside the SNS. The charges within are outputted in time series from the output OS as an image signal. After this signal is amplified by the amplifier inside the SDR,
It is input to the analog input terminal of PRS as the OS. P
RS outputs A/A in synchronization with the clock CK that it outputs.
D conversion is performed, and the digital image signals after A/D conversion are sequentially stored at predetermined addresses in the RAM.

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

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

In step (402), three flags JF, AFNG
.

Clear LMVDI. As will be described later, JF is a flag that does not indicate the in-focus state, AFNG is a flag that indicates that focus detection is impossible, and LMVDI is a flag that prohibits lens driving.

In step (403), the state of the focus area flag JFFLG set in the "focus detection" subroutine is determined, and if ], it is determined that the focus is in focus, and the process moves to step (404), where the focus state is controlled. . In step (404), both the focus flag JF and the lens drive inhibition flag LMVDI are set to 1. Next, in step (405), the constant 5RCNT is set to 3. As mentioned above, 5RCN
T is a variable representing the state of search operation, and 5PCNT
=3 means that the search operation has been completed. That is, once the object is in focus, it will be the same as when the search operation ends. Subsequently, in step (406), the flag TMACT
Set 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 restarted, and in step (408), the "judgment" subroutine is returned. Lens drive regulation timer is microcomputer PR
The timer uses the internal timer described in No. 3, and starts counting from the moment the risk is exceeded, and its contents can be read at will.

In step (403), the focus area flag JFF
If LG is 0, the process moves to step (4, 09), and the state of the low contrast flag L CF L G set in the "focus detection" subroutine is determined. Step (4
, 09), if the flag LCFLGfJ<1, it is assumed that the focus detection result is low contrast, and the process moves to step (4, IO).

In step (410), the search operation state variable 5RCNT
The state of is detected, and if it is not 0, the process moves to step (41, 1). The fact that the variable 5PCNT is not 0 means 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 focus detection impossible flag AFNG is set to 1 in step (411) so as not to perform the search operation again, and the lens drive prohibition flag LMVDI is set to 1 in the next step (412). If the flag is L M V D I months, step (1) of the "AF control" subroutine in FIG.
32) to move to step (133) and return to the ``rAF control'' subroutine. Step (13
8) Subsequent search operations will not be performed.

If the variable 5PCNT is 0 in step (4, I O), the process moves to step (414) and the continuous shooting AF flag F
Detects AF status.

In step (4], 4.), flag FAF is 1, that is,
If it is quick shooting AF, the process moves to step (412), and the flag L
Set MVDI to 1 to disable search operations.

When the flag FAF is 0, the process moves to step (415), in which case a search operation is performed in the "rAF control" subroutine.

In step (409), the low contrast flag LCFLG is set.
If is 01, that is, the contrast is sufficient, step (415)
Move to.

In step (41, 5), the in-focus vicinity flag CH3F
If LG is 1, the process moves to step (4) 6) and returns to the "judgment" subroutine. If the flag CHSFLG is 0 in step (4) 5), it is determined that the defocus amount is not near the in-focus area, and the process moves to step (417).

In step (417), the state of the lens drive regulation timer operation flag TMACT is determined, and if it is 0 and is 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 (422) and the subsequent lens drive regulation timer is controlled.

TMLNG is a constant that defines the operating time of the lens drive regulation timer. If the lens drive regulation timer that starts timing upon focusing is less than the above TMLNG,
Lens driving is prohibited, and when TMLNG is exceeded, lens driving is permitted.

In step (422), the value of the lens drive regulation timer being measured is compared with a predetermined constant 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) and returns to the "judgment" subroutine. If the latter is larger in step (422), the process moves to step (423), sets the lens drive prohibition flag to 1, and returns to the "judgment" subroutine in step (425).

To summarize the flow of the "judgment" subroutine explained above, if the focus detection result is in the in-focus area, the focus flag J is
Set F to 1, and lens drive prohibition flag T.
Set M V D I to 1. And Suizuji S
While the WI is on, a search operation is not performed even if the contrast becomes low, and at the same time a lens drive regulation timer is operated. 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, the search operation is not performed in the case of continuous shooting AF.

Even if the contrast is sufficient, if the focus is not focused,
39 If the focus amount is within the in-focus range, 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 a search is performed with low contrast, and the lens drive regulation timer is inactive, the lens is driven as is. If the lens drive regulation timer is operating, the specified time (
(defined as constant TMLNG), lens driving including search is not performed.

FIG. 4(f) shows a flowchart of the "lens drive" subroutine.

When this subroutine is executed, step (502)
communicates with the lens at , and sends two data rsJrPT
Enter HJ. "S" is the [defocus amount vs. focus adjustment lens (coefficient of protrusion amount)] specific to the photographic lens. For example, in the case of a fully extended single lens, the entire photographic lens is a focus adjustment lens, so S= 1, and in the case of a zoom lens, S changes depending on each zoom position.

"PTH" is the amount of protrusion of the focusing lens per output l pulse of the encoder ENC linked to the movement of the focusing lens LNS in the optical axis direction.

Therefore, the defocus of the current photographic lens is 1DEF.

A value obtained by converting the amount of protrusion of the focusing lens into the number of output pulses of the encoder, the so-called lens drive amount FP, is given by the following equation using S and PTH in Section 2.

F P = D E F x S / P T H step (503) executes the above equation as is.

In step (504), F obtained in step (503)
P is sent 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).

Next, in step (505), the continuous shooting AF flag FAF
Detect the state of. If the flag FAF is O, it is assumed that the focus adjustment is normal and the process moves to step (506) to return to the "lens drive" subroutine.

In step (505), FAF is 1, that is, continuous shooting AF.
If so, lens control specific to continuous shooting AF in steps (507) and (508) is performed.

In step (507), the process waits for a predetermined time, and this time LM corresponds to the drive time of the lens drive commanded in step (505). After instructing the lens to prohibit driving in step (508), the lens drive subroutine is returned in step (509). In the quick-shooting AF, as mentioned above, the rAE control and AF sub-control are performed alternately, and at this time the rAE control subroutine controls a series of release operations (film exposure 9 winding) using switch SW2.
It is executed by interrupt processing. Therefore, since the release operation is performed immediately after the rAF control subroutine ends, there is no time to drive the lens. Therefore, during AF continuous shooting, time for lens driving is created in the rAF control subroutine.

Furthermore, there is no search operation during continuous shooting,
Furthermore, since lens driving is completed within the ``rAF control'' subroutine, there is no need to determine the states of the flags PRMV and SRMU related to lens driving in the aforementioned main routine.

In the embodiment of the present invention, one microcomputer is used to perform the photographing operation and the focus adjustment operation; however, even if two microcomputers are used to perform the focusing operation independently, the present invention will still be effective. The effect is obvious.

In the embodiment, the lens drive time is simply waited for in step (507) in the "lens drive" subroutine, but another method is to detect the drive state of the lens and wait for a predetermined time. When the lens stops earlier than the specified time, it is more effective to return to the "rAF control" subroutine at that point.

Further, the quick shooting state may be recognized by actually detecting the switch SW2 instead of using the flag RLS.

[Explanation of effects]

As explained above, according to the present invention, when the camera is in continuous shooting mode, by limiting the lens driving time in the focus adjustment operation (subject image input, focus detection signal processing, lens driving) for each shooting, This makes it possible to adjust the focus with improved operability during quick shooting.

[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・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・Focal adjustment lens L
PR3・・・・・・・・・・・・・・・・・・・・・
・・・・・・Lens control circuit SNS・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
・・・Sensor device SDR・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・Sensor drive circuit patent applicant Canon Co., Ltd. 411Z (J)

Claims (1)

[Claims] The light flux from the subject that has passed through the photographic lens is received by a plurality of photoelectric conversion element arrays, the focal state of the photographic lens is detected using the output of the photoelectric conversion element array, and the above-mentioned What is claimed is: 1. A focus adjustment device for a camera that drives a photographic lens, characterized in that when the camera is in a continuous shooting state, a time required for driving the lens is limited.