JPH11211973A - Focusing device and camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize stable focusing regardless of the number of driving times of an optical element for focus detection or a movable part. SOLUTION: This focusing device is provided with the optical element for focus detection SM guiding luminous flux made incident through an image- formation optical system to a focus detection sensor SNS and moving between a focus detection position and a retreat position where it retreats from the focus detection position; and the focusing processing of the image-formation optical system is performed based on the detected result by the focus detection sensor. In such a case, the focusing processing is corrected in accordance with the number of moving times of the optical element SM between the focus detection position and the retreat position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a focus detection device used for a camera or the like.

[0002]

2. Description of the Related Art Most of auto-focusing devices of a single-lens reflex camera are designed to cover one to seven areas in a photographing screen.
By repeatedly performing a cycle of “focus detection (sensor signal input, focus detection calculation)” and “lens drive”, the subject is focused.

In recent years, a large number of focus detection areas are provided in a wide area of a photographing screen so that focus adjustment can be performed together with composition determination, or a photographer selects a focus detection area at a position where a subject is desired to be included in a composition. There has been proposed an apparatus that can perform focus adjustment while pursuing a moving subject while determining the composition.

When a plurality of focus detection areas are provided in this type of focus adjustment apparatus, a plurality of photoelectric conversion element arrays corresponding to the respective areas, that is, so-called sensors, are naturally required. Normally, these sensor rows are formed as the same semiconductor element, but the number of sensor rows also increases according to the number of focus detection areas, and an image formed by the focus detection optical system is projected over a wide range on the focus detection sensor. Need to be done.

Japanese Patent Application Laid-Open No. 5-150155 discloses that in a focus detection device having a large number of focus detection areas over a wide area, a focus detection area sensor having a large number of focus detection points is provided through a focus detection optical system. There has been proposed a process for correcting distortion and insufficient light quantity in a peripheral portion when an image is to be formed.

[0006] The magnification of the image projected onto the focus detection sensor as described above is smaller than the magnification of the conventional sensor. This is because a large area of the image is projected on the sensor, so if the image is not reduced, the sensor becomes large,
This is because the focus adjustment device itself becomes large.

[0007]

However, when the reduction ratio of the image projected on the focus detection sensor is increased, errors in the mechanism of the focus detection optical system are enlarged on the focus detection sensor. The influence of wear caused by an increase in the number of times of driving of the stop mechanism of the quick return mirror and the sub-mirror which cannot be eliminated cannot be ignored.

To reduce these errors, it is conceivable to improve the abrasion resistance of the members constituting the stop mechanism. However, other performances (high-speed drive, weight reduction, etc.) required for the mechanism are reduced. And the cost increases.

[0009]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, a focus detection position for guiding a light beam incident through an imaging optical system to a focus detection sensor and a retreat from the focus detection position. In a focus adjustment device having a focus detection optical element that moves between the retracted position and a focus adjustment process of the imaging optical system based on the detection result of the focus detection sensor, a focus detection position of the focus detection optical element The focus adjustment process is corrected according to the number of movements between the position and the retreat position.

The second invention of the present application has a focus adjusting optical system that switches between a focus adjustable state and a photographable state, and after the focus adjustment processing, sets the focus adjustable optical system to a focus adjustable state prior to photographing. In the camera that switches from the to the shooting enabled state and returns to the focus adjustable state after shooting,
The focus adjustment processing is corrected according to the number of times the focus adjustment optical system switches between the focus adjustable state and the photographable state.

Thus, the movable part of the focus detecting optical element or the focus adjusting optical system abuts on the stop member (collision).
By doing so, it is possible to reduce the influence on the focus adjustment process due to the abrasion between the two when the focus detection position or the focus adjustment optical system is positioned at a position where the focus adjustment can be performed.

In each of the above inventions, the correction data for the focus adjustment processing may be stored in the storage means.

[0013]

(First Embodiment) FIG. 1 shows a focusing optical system of a single-lens reflex camera provided with an automatic focusing device according to a first embodiment of the present invention.

In FIG. 1, reference numeral SM denotes a sub-mirror (optical element for focus detection referred to in the claims), which has an elliptical curved shape because it functions in place of a conventional field lens. DP is an aperture, and an opening is provided at the center. The elliptical sub-mirror SM has a function of forming an image of the light passing through the opening DP near the exit pupil of an objective lens (not shown).

AFL has two pairs of four lenses AFL-1.
a, AFL-1b, AFL-2a, and AFL-2b, which are secondary imaging lenses.
It is arranged behind the stop DP.

SNS has a total of four sensor surfaces SNS-1
a, SNS-1b, SNS-2a, and SNS-2b are area sensors composed of CCDs and the like. The area sensor SNS is arranged so as to receive the image corresponding to each secondary imaging lens AFL.

In the focus adjusting optical system shown in FIG. 1, when the focus of the photographing lens is ahead of the film surface, the subject images formed on each pair of sensor arrays are close to each other, and the focus is backward. In some cases, the subject images are separated from each other. Since the relative positional displacement amount of the subject image has a specific functional relationship with the defocus amount of the photographing lens, if each sensor array pair performs an appropriate calculation on the sensor output, the defocus amount of the photographing lens, A so-called defocus amount can be detected.

By adopting the above-described configuration, even in the vicinity of the center of a range photographed or observed by an objective lens (not shown), even an object whose light amount distribution changes only in one direction, up and down or left and right, is focused. It is possible to detect, and focus can be detected for an object in an opening around the center.

FIG. 2 shows the arrangement of the optical system of a single-lens reflex camera having the focusing optical system of FIG.

In this figure, LNS is a photographing lens unit,
QRM is a quick return mirror, FSCRN is a focusing screen, PP is a pentaprism, EPL is an eyepiece, FP
LN is a film surface, and RM1 and RM2 are reflection mirrors. Further, as described above, SM is a sub-mirror, DP is an aperture, AFL is a secondary imaging lens, and SNS is an area sensor. These components constitute a focus adjusting optical system described in the claims. Further, STP is a restraint member (stop member in the claims) that determines the stop position of the sub mirror SM and the quick return mirror QRM.

When the quick return mirror QRM is positioned by the restraining member STP during focus adjustment, the sub-mirror SM integrally attached to the quick return mirror QRM is also positioned, so that the optical system movable part can be positioned for focus detection. .

The detailed description of the components that satisfy the optical performance, such as the infrared cut filter, the cover glass on the sensor, and the light receiving surface, is omitted here.

FIG. 3 shows an example of a specific configuration of a camera provided with the above-mentioned automatic focusing device.

In FIG. 3, PRS is a camera control circuit, for example, a CPU (Central Processing Unit), ROM, RAM,
It comprises an EEPROM and a one-chip microcomputer having an A / D converter. This control circuit PRS has an R
A series of camera operations such as an automatic exposure control operation, an automatic focus adjustment operation, and a film winding / rewinding operation are controlled in accordance with a camera sequence program stored in the OM. Therefore, the control circuit PRS outputs the communication signals SO,
SI, SCLK, communication selection signals CLCM, CSDR, C
The DDR is used to communicate with peripheral circuits in the camera body and a control device in the lens to control the operation of each circuit and lens.

Note that SO is a data signal output from the control circuit PRS, SI is a data signal input to the control circuit PRS, and SCLK is a synchronous clock of the signals SO and SI. LCM is a lens communication buffer circuit that supplies power to the lens power supply terminal VL when the camera is in operation and that the selection signal CLCM from the control circuit PRS has a high potential level (hereinafter abbreviated as “H”). Sometimes
It becomes a communication buffer between the camera and the lens.

When the control circuit PRS sets the communication selection signal CLCM to "H" and sends out predetermined data as a signal SO in synchronization with the synchronization clock SCLK, the lens communication circuit LC
M is the signal SCL via the camera-lens communication contact
The buffer signals LCK and DCL of K and SO are output to the lens. At the same time, a buffer signal of the signal DLC from the lens is output to SI, and the control circuit PRS outputs SCLK
, Lens data is input from SI.

DDR is a circuit for detecting and displaying the various switches SWS. The signal DDR is selected when the signal CDDR is "H", and is controlled by using the signals SO, SI and SCLK.
Controlled by S. That is, based on data sent from the control circuit PRS, the display of the display circuit DSP of the camera is switched, and the on / off state of various operation members of the camera is notified to the control circuit PRS by communication.

SW1 and SW2 are release buttons R shown in FIG.
This is a switch linked to the LSSW. The switch SW1 is turned on by pressing the release button RLSSW in the first stage, and the switch SW2 is turned on by the second release button RLSSW.
Turns on by pressing down in stages. The control circuit PRS is a switch SW
Turn on 1 to perform photometry and automatic focus adjustment.
Is turned on as a trigger, exposure control and subsequent film winding are performed.

The switch SW2 is connected to an "interrupt input terminal" of a control circuit PRS which is a microcomputer. Therefore, even when the program is executed when the switch SW1 is turned on, an interrupt is generated by turning on the switch SW2, and the control circuit PRS immediately shifts the control to a predetermined interrupt program.

MTR1 is a motor for feeding the film, and MTR2 is a motor for mirror up / down and charging of the shutter spring. Control of forward rotation and reverse rotation is performed by respective drive circuits MDR1 and MDR2. The signal M1 input from the control circuit PRS to each of the drive circuits MDR1 and MDR2
F, M1R, M2F, and M2R are motor control signals. By the operation of the motor MTR2, the quick return mirror QRM and the sub-mirror SM move up to move to the photographing position (a retract position in the claims) or move down to move to the focus detection position.

The mirror phase detection switches MPS1 and MPS2 for detecting the positions of the mirrors QRM and SM are provided.
Is input to the control circuit PRS, and the control circuit PRS
RS drives the mirror based on these signals (ie,
(Operation of the motor MTR2).

MG1 and MG2 are magnets for starting the driving of the first and second curtains of the shutter, respectively.
When G1 and SMG2 are input to the amplification transistors TR1 and TR2, current is supplied and shutter control is performed.

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

This embodiment shows an example of a zoom lens. When a focus adjustment command is sent from a camera, a focus adjustment motor LTMR is sent to the signals LMF and LMF in accordance with the drive amount and direction sent at the same time. Driven by the LMR, the focus is adjusted by moving the optical system in the optical axis direction.

The amount of movement of the optical system is determined by detecting the pattern of a pulse plate that rotates in conjunction with the optical system with a photocoupler and outputting a number of pulses corresponding to the amount of movement.
Monitoring is performed using the CF pulse signal SENCF. Then, a pulse signal SE is generated by a counter in the lens control circuit LPRS.
When the NCF is counted and the predetermined movement is completed, the in-lens control circuit LPRS sets the signals LMF and LMR to low potential levels (hereinafter abbreviated as “L”), and the motor LMTR
Control.

Therefore, once the focus adjustment command is sent from the camera, the control circuit PRS of the camera does not need to be involved in driving the lens at all until the driving of the lens is completed. Further, when a request is received from the camera, the contents of the counter can be transmitted to the camera.

When an aperture control command is sent from the camera, the stepping motor DMTR is driven to drive the aperture according to the number of aperture stages sent at the same time. In addition,
Since the stepping motor DMTR can perform open control, it does not require an encoder for monitoring the operation.

ENCZ is an encoder circuit attached to the zoom optical system, and the in-lens control circuit LPRS receives the signal SENCZ from the encoder circuit ENCZ to detect the zoom position. The lens parameters at each zoom position are stored in the in-lens control circuit LPRS, and when requested by the camera-side control circuit PRS, the parameters corresponding to the current zoom position are sent to the camera.

An exposure control sensor SPC receives light from a subject through a photographing lens.
PC is input to the analog input terminal of the control circuit PRS,
After the A / D conversion, it is used for automatic exposure control according to a predetermined program.

SDR is a focus detection area sensor SNS.
Is selected when the signal CSDR is at “H”, and the control circuit PR is selected by using the signals SO, SI, and SCLK.
Controlled by S.

The control circuit PRS receives image information of a subject image formed on each area sensor pair, and thereafter performs a predetermined focus detection calculation to obtain a defocus amount of the photographing lens. Next, the automatic focusing operation of the camera having the above configuration will be described with reference to the flowcharts of FIGS.

First, FIG. 4 shows a sequence of the entire camera. When power supply to the circuit shown in FIG. 3 is started, the control circuit PRS starts execution from step (000) in FIG.

In step (001), the switch S
The state of W1 is detected, and if it is off, step (002)
Go to to initialize flags and variables that need to be initialized.
Then, it is detected in step (001) that the switch SW1 is turned on again.

If the switch SW1 is turned on in step (001), the process moves to step (003) to start the operation of the camera. In step (003), an "AE control" subroutine such as photometry and state detection and display of various switches is executed. When the “AE control” subroutine ends, the flow shifts to step (004).

In step (004), an "AF control" subroutine is executed. Here, accumulation of sensors, calculation of focus detection, and automatic focus adjustment operation of lens driving are performed.

When the "AF control" subroutine ends,
At step (005), the state of the switch SW2 is detected. If the switch SW2 is off, the process returns to step (001) again, and steps (003), (004), and (005) are repeatedly performed until the switch SW1 is turned off. If the switch SW2 is on, a "release control" subroutine is executed in step (006).

FIG. 11 shows the "release process" subroutine. When this subroutine is called by pressing the switch SW2, the processing is performed from step (510).

In step (511), it is determined from the camera mode and the result of autofocusing and the state of accessories such as strobes whether or not it is a condition that the shutter can be run to execute photographing. If it cannot be executed (NO), the process of step (516) is performed and the process returns. If the execution is possible (YES), step (5)
At 12), a mirror-up process is performed. As a result, the quick return QRM and the sub-mirror SM (or the focusing optical system including them) start displacing from the focus detection position (or the focus adjustable state) to the shooting position (or the shooting enabled state).

When the mirror-up process is completed, the front-curtain / back-curtain running process is performed in step (513), and the shutter is driven.

Subsequently, in step (514), mirror down processing is performed, and the quick return QRM and the sub mirror SM return from the photographing position to the focus detecting position. As a result, since the focus adjusting optical system is driven once, the number of driving operations MNM is increased by one in step (515), and the process returns from the "release processing subroutine" in step (516).

Here, the actual operation of the focus adjusting optical system and the shutter in the release processing control will be described with reference to FIGS.
This will be described with reference to FIGS.

When the control circuit PRS (CPU) determines that the release button RLSSW shown in FIG. 12 is pushed and the switch SW2 is turned on, the control circuit PRS reversely rotates the motor MTR2. As a result, the mirror drive gear 126 and the shutter charge gear 142 rotate, and the movable mirror (quick return QRM and sub mirror SM) 134 is raised as shown in FIG. The control circuit PRS controls the shutter charge lever 14
6 stops the motor MTR2 when the charge release operation is performed.

In this state, the shutter operation is performed, and the motor MTR2 is further rotated in reverse with the completion of the running of the rear group of blades after the shutter. As a result, the mirror driving gear 126
14 and the shutter charge gear 142 rotates,
The movable mirror 134 goes down as shown in FIG. And
The control circuit PRS stops the motor MTR2 when the shutter charge lever 146 performs a charging operation.

With the above operation, it is considered that the mirror drive is performed once, and the control circuit PRS determines in step (51) in FIG.
In step 5), the value of the mirror drive count MNM stored in the EEPROM is increased by one.

After the running of the rear group of shutter blades, the control circuit PRS rotates the motor MTR1 in the reverse direction to perform a film winding operation. When the film rewinding operation is completed, the process enters a standby state for photographing the next frame, and returns to step (001) to continue the processing. Thereafter, the release button RLSSW is pushed (the switch SW2 is turned on). The above operation is repeated each time the shooting is performed.

FIG. 5 shows a flowchart of the "AF control" subroutine executed in step (004). When the "AF control" subroutine is called, AF control is performed from step (011) through step (010). First, the step (01
In 1), a "focus detection" subroutine is executed. Here, accumulation and readout of image signals to each sensor for focus detection operation and focus detection calculation are performed. "Focus detection"
The subroutine will be described later.

In the next step (012), an "area selection" subroutine for selecting which of the plurality of focus detection areas is currently selected and using the defocus amount of that area is selected. Execute. In the present embodiment, the automatic selection mode is normally set in which all the areas are selected. However, the selection area can be specified by pressing the selection area setting switch in the various switches SWS in FIG. . Further, it is also possible to detect the line of sight of the photographer by using a line of sight input device (not shown) and designate a selection area.

In step (013), "lens drive"
Execute a subroutine. Here, step (01)
In the defocus amount detected in 1), step (0)
Lens drive is performed based on the defocus amount of the area selected in 12). The “lens drive” subroutine will be described later.

After the lens driving is completed, the "AF control" subroutine is returned from step (014).

FIG. 6 shows a flowchart of the "focus detection" subroutine executed in step (011). When this subroutine is called, the focus detection operation from step (111) is executed through step (110).

First, in step (111), it is determined whether or not the power is turned on and the first AF control is performed. If it is the first AF control, the process proceeds to step (112) to initialize the selected sensor. Become

Next, in step (113), "start accumulation"
Execute a subroutine. This subroutine is a routine for starting the accumulation operation of the sensor. Specifically, a storage start command is sent to the sensor drive circuit SDR to start the storage operation of the area sensor SNS, and at the same time, a sensor storage end signal / TI from the sensor drive circuit SDR.
The input / output is set so that the control circuit PRS can recognize “storage completion” by the NTE.

When the accumulation end signal becomes "H", the control circuit PRS communicates with the sensor drive circuit SDR to obtain accumulation completion pixel information. By performing the communication of the accumulation completion pixel information, / TINTE becomes “L”. In the area sensor, even if the accumulation is completed for some pixels, there are pixels that are still accumulating, so it is possible to know which pixels have completed accumulation and which pixels are still accumulating from the accumulation completion pixel information, The image signal is read from the pixel whose accumulation has been completed.

Until the reading of all the pixels is completed, “accumulation completion recognition” ← / → “image signal reading” is repeated.

By the above operation, the area sensor SN
The processing is performed until the accumulation of all S is completed and the image signals of all the pixels are read.

After inputting the image signal of the sensor SNS in step (151), the interrupt routine is returned in step (152). The input of the image signal is a serial A / D conversion of an output VIDEO input to an analog input terminal of the control circuit PRS, and an image signal data in a state where an optimal accumulation control is performed by performing an operation described later on the digital data. After that, the data is sequentially stored in a predetermined RAM area.

In step (126) of FIG. 6, it is determined whether or not the focus detection calculation corresponding to all the sensors has been completed. If not, the process proceeds to step (114).
If all the processes have been completed, the process proceeds to step (127).

To summarize the above, step (11)
After starting the accumulation operation in 3), steps (114) to (1) are performed while waiting for the image signal of each sensor to be read.
26) is repeatedly executed, and focus detection calculation is sequentially performed from the sensor from which the image signal is read.

When the focus detection calculations for all the sensors are completed, the "focus detection" subroutine is returned in step (127).

Here, in the step (151) of the "image signal input" subroutine, an image signal conversion operation is executed. The purpose of the image signal conversion performed here is to compare a signal BTIME which is an input for accumulation control (hereinafter referred to as AGCLV).
L) is corrected for the output variation between lines due to the common setting for all areas. The cause of the variation is a variation in the sensitivity of the sensor itself, or a variation when the comparison level AGCLVL is input to the control circuit of each area sensor. In the present embodiment, the comparison level AGC
The LVL is adjusted and set.

Here, as shown in FIG. 8A, it is assumed that an output having a variation is obtained for a uniform luminance surface. The bending of each output is unevenness due to each optical system up to the sensor, and is called so-called shading unevenness. When these corrections are performed, in the correction image signal conversion, a correction coefficient SHn (I) obtained by the following equation is obtained for each pixel of each line, and each output (A / D conversion value) Imn (I ) And SHn (I) result IMn
This is performed by storing (I) in a predetermined location on the RAM.

SHn (I) = {MAX−Imn (I)} / Imn (3) IMn (I) = Imn (I) + Imn (I) × SHn (I) (2) The correction coefficient obtained by the equation (3) is stored in a RAM (storage means in claims) in the control circuit PRS in advance. The correction coefficient also serves as a correction coefficient for uneven output of the focus detection sensor by the optical system of the defocus amount detecting means, as is apparent from the above equation (3).

In this example, the above-mentioned correction of shading unevenness and output unevenness between lines are eliminated at once.
In other words, the two non-uniformities can be corrected at once by setting the correction coefficient obtained by the above equation (3) not to the maximum value MAXn for each line but to the maximum value MAX in all lines. Becomes This situation is shown in FIG.
(A) and (b) show. If the correction of the shading unevenness and the correction of the output unevenness between the lines are not performed, the prediction operation performed thereafter is not accurately processed.

In step (115) of FIG.
It is determined whether or not the NS image signal input processing has already been completed, and if it has been completed, the process proceeds to step (116) to execute a focus detection calculation based on the image signal of the sensor SNS.

After the image signal input processing of the sensor SNS is completed, a correction operation (dark current correction) for the above image signal is performed, and as a calculation for detecting the defocus amount, a displacement on the sensor is calculated using the following equation B. A correlation operation is performed to determine the amount (prediction value). At this time, a correction (hereinafter, referred to as a mirror driving number correction) for the focus adjustment processing described in the claims is performed, and highly accurate focus detection according to the characteristics of the focus adjustment optical system is enabled.

Pr ′ = Pr + μ · MNM · D (x, y) (Equation B) Here, Pr ′ is a prediction value to which the number of times of mirror driving has been corrected. μ is a correction coefficient. Also, M
NM is the number of times the mirror is driven. x and y are coordinates representing a focus detection area for performing focus detection. D (x, y) is a function for deriving a drive count correction value having x and y as parameters. D is a table corresponding to the viewing area coordinates x and y, and has constants in ROM or EEPROM. When this is represented by a function, an equation may be defined and calculated, and used instead of the constant obtained from the table.

The term μ · MNM · D (x, y) is
If other corrections to the prediction value Pr need to be performed first, they cannot be added. Therefore, the correction amount is stored in the correction value storage area TDPR prepared in the RAM as follows: TDPR = μ · MNM · D (x, y) (Equation D) The prediction value Pr ″ is corrected as follows: Pr ′ = Pr ″ + TDPR (Equation E)

The correction prediction value Pr ′ obtained as described above is converted into the defocus amount of the photographing lens using the characteristic parameters K and G of the secondary imaging lens AFL.

Assuming that the correction prediction value is Pr ′, the defocus amount Df is as follows: Df = KPr ′ / (1−KPr ′ / G) (Equation C)

FIG. 10 shows a flowchart of the "lens drive" subroutine. When this subroutine is executed, in step (311), the control circuit PRS communicates with the lens unit LNS to communicate the two data S and PT.
Obtain H.

In step (312), the mirror drive frequency correction process described below is performed. Here, the defocus amount Df to be focused and the data S, PTH determined above are obtained.
The value obtained by converting the amount of movement of the focus adjustment optical system into the number of output pulses of the encoder, that is, the so-called lens drive amount FP,
Will be given by

FP = Df · S / PTH (Equation A) In the next step (314), the lens drive amount FP obtained in step (313) is calculated using the lens unit LNS. To instruct the driving of the focusing optical system.

In the next step (315), communication with the lens unit LNS is performed to detect whether or not the driving of the lens driving amount FP commanded in the step (314) has been completed. Then, the "lens drive" subroutine is returned.

As described above, according to the present embodiment, the sub-mirror SM constituting a part of the focusing optical system is provided for the area sensor SNS corresponding to a wide subject area.
In performing the correction according to the number of driving times, by performing a predetermined calculation according to the number of driving times on the defocus amount obtained from the sensor output, the minute displacement of the optical system mechanism by the mirror driving was adjusted. An equivalent effect can be obtained. That is, it is possible to reduce the influence of the minute displacement of the optical system mechanism, which depends on the number of times of driving the sub-mirror SM, on the focus adjustment.

In the present embodiment, a mirror drive correction process is performed on the prediction value Pr in the focus detection calculation of the sensor. Since the prediction value is obtained for the focus detection line, it is possible to perform correction for each focus detection line in a focus adjustment device having a configuration in which a plurality of focus detection lines are included in the same focus detection area. is there.

(Second Embodiment) FIG. 15 shows a flowchart of the "AF control" subroutine executed in the automatic focusing apparatus according to the second embodiment of the present invention. Note that the schematic configuration of the apparatus, the arrangement in the camera, and the circuit are exactly the same as in the first embodiment. The same applies to the sequence of the entire camera.

When the "AF control" subroutine is called, AF control is performed from step (411) onward through step (410).

First, in step (411), it is determined whether a specific focus detection area is selected in the arbitrary selection mode (whether the all focus detection area is selected in the automatic selection mode).

If not in the optional selection mode, the following steps (412) to (415) are executed in the same manner as in the first embodiment. If it is determined in the above step (411) that the mode is the optional selection mode, the process proceeds to step (416). In the arbitrary selection mode, as described in the first embodiment, the focus detection area is selected by the selection area setting switch in the various switches SWS of FIG. 3 or the selection is performed by the photographer's line of sight.

In step (416), the signal B
The comparison level AGCLVL in TIME is converted to be optimal for the sensor SNS in the specified area. That is,
Normally, assuming automatic selection, the comparison level AGCLVL adjusted and set for the sensor row having the highest output on the uniform luminance surface is converted into a level adapted to an arbitrary selection area.

A specific description will be made with reference to FIG. In this case, since the area (LINE) 3 has the highest output, no conversion is necessary if the area 3 is selected. Assuming that the area of the area 1 is selected, in this case, it is sufficient to accumulate more than the normal control level so that “MAX1 = MAX3”. Therefore, the comparison level AGCLVL may be increased by performing the following conversion on the comparison level AGCLVL.

AGCLVL = AGCLVL × (MAX3 / MAX1) (4) The above equation (4) holds similarly for other areas, that is, areas 2 to 4. In general, the conversion formula for area n can be expressed as follows: AGCLVLn = AGCLVL × (MAX / MAXn) (5) if the maximum value in all areas is MAX. In step (416), MAX / MAXn, which is a conversion coefficient for each line, is fetched from the area stored at the time of adjustment, and the conversion of equation (5) is performed. In a succeeding step (417), a "focus detection 2" subroutine is executed. Here, focus detection calculation is performed from accumulation and readout of image signals of the selected sensor array for the focus detection operation. The “focus detection 2” subroutine will be described later.

In the next step (418), the comparison level is returned to the initial setting in preparation for the next focus detection operation.

When the focus detection calculation for the selected area is completed, the "lens drive" subroutine is executed in step (414) based on the result, similarly to the first embodiment, and the "AF control" subroutine is executed in step (414). 41
Return to step 5).

FIG. 16 shows a flowchart of the "focus detection 2" subroutine executed in step (417). When the "focus detection 2" subroutine is called, the focus detection operation of step (211) and subsequent steps is performed via step (210).

First, in step (211), it is determined whether or not the power is turned on and the first AF control is performed. If so, the selection sensor is initialized in step (212). .

Next, in step (213), "start accumulation"
Execute a subroutine. However, here, "Start accumulation"
The subroutine sets the sensor accumulation end signal from the sensor drive circuit SDR to a signal / TINTE, and this signal / TIN
This is a subroutine for setting so that the control circuit PRS can recognize “storage completion” only by TE.

When the accumulation operation of the selected sensor is started in step (213), the flow proceeds to step (214). In this step (214), it is determined whether or not the accumulation of the sensor SNS has been completed. If the accumulation has not been completed, the process remains in step (214). One area includes one or more sensor lines. Step (214)
If the accumulation of the sensor array SNS has been completed at step (2), the process proceeds to step (215) to input the image signal of the sensor array SNS. Here, the conversion of the image signal is correct only by the conversion for correcting the shading unevenness in each line as in the related art.

Subsequently, at step (216), the sensor S
The focus detection calculation based on the NS image signal is executed. In the focus detection calculation here, similarly to the first embodiment, the value of the corrected prediction value Pr ′ may be obtained by performing correction of Expression B, but in the present embodiment, no correction is made here.

FIG. 17 shows a flowchart of the "lens drive" subroutine. When this subroutine is executed, in step (611), the lens unit LN
It communicates with S to obtain two data S and PTH.

Next, in step (612), based on the prediction value Pr obtained by the above-described focus detection calculation, the lens is driven by using the following equation C ′ to obtain a defocus value Df to be adjusted in focus. In the present embodiment, the process of correcting the number of times of mirror driving is performed here. Df = KPr / (1−KPr / G) (Equation C ′) Then, the number of mirror driving times is corrected for the defocus amount Df by the following equation F.

Df ′ = Df + ν · MNM · d (x, y) (Equation F) Df ′ is the defocus amount to which the number of mirror driving times has been corrected. ν is a correction coefficient. MNM is the number of times the mirror is driven. x and y are coordinates representative of a visual field region where focus detection is performed. d (x, y) is a function for deriving a drive count correction value having x and y as parameters. d is a table corresponding to the coordinates x and y of the visual field area, and the constant is stored in ROM or EEPROM.
I have it in the OM. When this is represented by a function, it is sufficient to define and calculate an equation and use it instead of a constant obtained from the table.

In step (613), the value obtained by converting the amount of movement of the focusing optical system into the number of output pulses of the encoder using the defocus amount Df 'to be adjusted after the correction and the data S and PTH obtained as described above. The lens driving amount FP is calculated using the following equation A ′.

FP = Df ′ · S / PTH (Equation A ′) In the next step (614), the lens drive amount FP obtained in step (613) is calculated by using the lens. A command is sent to the unit LNS to drive the focusing optical system.

In the next step (615), it communicates with the lens unit LNS to detect whether or not the driving of the lens driving amount FP commanded in the step (614) has been completed. When the driving has been completed, the flow proceeds to step (616). Then, the process returns to the "lens drive" subroutine.

As described above, it is possible to reduce the influence of the minute displacement of the optical system mechanism, which depends on the number of times of driving the sub-mirror SM, on the focus adjustment.

When the focus detection calculation for the selected focus detection area is completed, the subroutine "focus detection 2" is returned in step (217) of FIG.

In the present embodiment, when an arbitrary area is selected from a plurality of focus detection areas by the photographer's intention, it is possible to optimally control the correction of the focus adjustment processing in the selected area. Becomes Also, since the prediction value is stored without correction,
When performing focus adjustment, the prediction value is given as raw information that does not correct the displacement of the mirror SM. For this reason, the corrected defocus value can be reflected in the content of the focus adjustment operation as information resulting from the effect of the correction processing.

With the configuration as in the first and second embodiments described above, the number of mirror driving times is corrected for each area even for a plurality of area rows that do not always have the same characteristics. be able to. Therefore,
The mass of the mechanism constituting the focus adjustment optical system can be reduced, and a focus adjustment device having advantages of high-speed operation, light weight, and continuous accuracy can be realized.

(Third Embodiment) In the first and second embodiments, the correction formula and the related threshold value / coefficient have been specifically described. However, these portions are stored in a nonvolatile rewritable storage medium. It may be possible to flexibly change the configuration by storing it.

For example, by storing the correction formula in the EEPROM, it is possible to change the correction formula, correction value, and threshold value after confirming the actual effect of the correction after a certain number of mirror driving times. Become.

[0112]

As described above, according to the present invention,
When the movable part of the focus detection optical element or the focus adjustment optical system is positioned at a focus detection position or a position where the focus adjustment optical system is in a focus adjustable state by abutting (colliding) with a stop member. In addition, it is possible to reduce the influence of the contact abrasion of the two on the focus adjustment processing. Therefore, stable focus adjustment can be performed irrespective of the number of times the focus detecting optical element or the movable section is driven.

[Brief description of the drawings]

FIG. 1 is a perspective view of a focus adjustment optical system of an autofocus camera including an autofocus device according to a first embodiment of the present invention.

FIG. 2 is a layout diagram of a focus adjusting optical system of the camera.

FIG. 3 is a block diagram of an electronic control system of the camera.

FIG. 4 is a sequence flowchart of the entire camera.

FIG. 5 is a flowchart of an AF control subroutine of the camera.

FIG. 6 is a flowchart of a focus detection subroutine of the camera.

FIG. 7 is a flowchart of an accumulation completion process of the camera.

FIG. 8 is a graph showing an effect of shading correction in the camera.

FIG. 9 is a graph showing an effect of shading correction in the camera.

FIG. 10 is a flowchart of a lens driving subroutine in the camera.

FIG. 11 is a flowchart of a release processing subroutine in the camera.

FIG. 12 is a plan view of the camera.

FIG. 13 is a side view of a mirror driving mechanism (capturable state) of the camera.

FIG. 14 is a side view of a mirror driving mechanism (a focus adjustable state) of the camera.

FIG. 15 is a flowchart of an AF control subroutine of the autofocus camera according to the second embodiment of the present invention.

FIG. 16 is a flowchart of a focus detection subroutine in the camera of the second embodiment.

FIG. 17 is a flowchart of a lens driving subroutine in the camera of the second embodiment.

[Explanation of symbols]

 SM Submirror DP Aperture AFL Secondary imaging lens SNS Area sensor LNS Photographing lens unit QRM Quick return mirror FSCRN Focusing plate PP Penta prism EPL Eyepiece FPLN Film surface RM1, RM2 Reflection mirror STP Restraint member PRS Control circuit MTR1, MTR2 Motor RLSW switch

Claims (8)

[Claims] A focus detection optical element that moves between a focus detection position that guides a light beam incident through an imaging optical system to a focus detection sensor and a retract position that retracts from the focus detection position; A focus adjustment device that performs a focus adjustment process of the imaging optical system based on a detection result of a sensor, wherein a focus adjustment process is performed according to the number of times the focus detection optical element moves between the focus detection position and the retreat position. A focus adjustment device for performing correction on the image. 2. The focus adjustment device according to claim 1, wherein the focus detection optical element is positioned at the focus detection position by moving from the retreat position and abutting against a stop member. 3. The focus adjustment apparatus according to claim 1, further comprising a storage unit configured to store correction data of a focus adjustment process according to the number of movements. 4. A camera comprising the focus adjusting device according to claim 1. 5. A focus adjusting optical system which switches between a focus adjustable state and a photographable state.
A camera that switches the focus adjusting optical system from the focus adjustable state to the photographable state prior to photographing, and returns to the focus adjustable state after photographing, the focus adjustable state of the focus adjusting optical system and the photographable state. A camera that performs correction for focus adjustment processing in accordance with the number of times of switching between states. 6. The camera according to claim 5, wherein the focus adjustment optical system is switched between the focus adjustable state and the photographable state by moving a movable portion. 7. The movable part is positioned at a position where the focus adjustment optical system is brought into the focus-adjustable state by moving the focus adjustment optical system from the position where the photographable state is brought into contact with a stop member. The focus adjustment device according to claim 6, wherein the focus adjustment is performed. 8. The camera according to claim 5, further comprising storage means for storing correction data for the focus adjustment processing.