JP5772897B2 - Focus adjustment device and photographing device - Google Patents

Description

The present invention relates to a focus adjustment device (automatic focusing device) mounted on a photographing device such as a camera and a photographing device including the same.

A digital camera that forms an optical image of a subject on a solid-state image sensor such as a CCD or CMOS via an imaging lens, and records an image signal output by photoelectric conversion by the image sensor on a recording medium or the like Has been put to practical use. In such a digital camera, there is no parallax, it is possible to focus accurately (focus on) even when the subject depth is shallow or far away, and there is no need to provide a dedicated sensor. Since there is an advantage, a contrast type autofocus (AF) apparatus is used.

In the contrast method, a focus adjustment lens (focus lens) is moved step by step at a predetermined interval (pitch), and a focus evaluation value (for example, integration of high-frequency components of an image signal obtained from a solid-state image sensor) is based on each photographed image. Value) and relative evaluation of these focus evaluation values, and the lens position at which the focus evaluation value is maximized is set as the focus position (focus position) (for example, Patent Document 1 below) reference).

By the way, the step movement and the calculation of the focus evaluation value are repeatedly performed to detect an appropriate focus position, and an autofocus operation (hereinafter referred to as AF) that moves the focus adjustment lens to the focus position. When an operation that affects the focus evaluation value, for example, a zoom operation (an operation to change the shooting magnification) is performed during the operation), it is useless to continue the AF operation during the operation. Since the AF operation also involves lens driving, it is not preferable from the viewpoint of power saving. For this reason, Patent Document 2 below discloses a technique in which, when a zoom operation is performed during an AF operation, the AF operation is interrupted for a certain period of time.

However, in this technique, when the AF operation is restarted after a certain time has elapsed, the zoom operation is performed between the focus evaluation value obtained before the stop and the focus evaluation value obtained after the restart. For this reason, the focus position is obtained using the focus evaluation value obtained before the stop even though the continuity is often impaired (relative evaluation criteria are changed). For this reason, it may become impossible to detect the in-focus position, or problems such as determining a position different from the proper in-focus position as the in-focus position (false in-focus) may occur.

The problem of false focusing will be described with reference to FIG. In FIG. 9, the horizontal axis represents the position of the focus adjustment lens, and the vertical axis represents the focus evaluation value. Starting from the start position a, a → b → c → d
If the step evaluation is performed in the order of e → f → g → h and the focus evaluation value is calculated at each position (a to h), the focus evaluation value is maximized at the position g. It is required as an appropriate in-focus position. However, for example, if the zoom operation is performed at the position d, the focus evaluation value thereafter is affected by this operation, and if the course of d → e ′ → f ′ is followed, the focus evaluation value is maximum. The position d to be obtained is obtained as the in-focus position, and false in-focus occurs.

As a countermeasure against such a problem of false focusing, for example, as disclosed in Patent Document 3 below, when a teleconversion lens (telecon) is attached during AF operation, A
The F operation is restarted, or the AF operation is restarted when the hue of the image changes during the AF operation or when an aperture change operation is performed as disclosed in Patent Document 4 below. What is made is known.

However, operations that affect the focus evaluation value, such as a zoom operation or an aperture change operation, may be frequently performed, and whenever the AF operation is restarted every time such an operation is performed, Rebooting is frequently performed, which causes a problem that the operation feeling may be impaired.

Therefore, an object of the present invention is to enable detection of an appropriate in-focus position without impairing the operational feeling even when an operation that affects the focus evaluation value is performed.
Japanese Patent Laid-Open No. 10-142488 Japanese Patent Laid-Open No. 2003-5018 JP-A-8-51563 JP-A-6-86141

According to the present invention comprises an operation unit for operating the execution or stop of the automatic focusing operation, and a control unit which performs seek control to acquire an evaluation value by driving the focusing lens, wherein the control unit, the operating unit Even if the operation of executing the autofocus operation by is continued, if the photographing magnification change operation is performed during the search control for driving the focus adjustment lens in the first direction , The search control is stopped until there is an execution operation after the autofocus operation stop operation by the operation unit, and after the search control is stopped, the photographing magnification change operation is ended and the autofocus by the operation unit is completed. when the operation of the run after the operation of the stop of the operation, after driving the focusing lens to a predetermined position, the Review by driving the focusing lens in the first direction A focus adjustment device is provided in which a value is obtained and the predetermined position is a position away from the position of the focus adjustment lens when the search control is stopped to the side opposite to the first direction. Is done.

In the present invention, the predetermined interrupt includes manual focus adjustment operation, change operation from auto focus mode to manual focus mode, change of photographing magnification, change of aperture, change operation of focus detection area, focus lock operation , A focus preset operation, and an elapse of a predetermined stop time or more can be exemplified.

In the present invention, the stop of the autofocus operation is instructed by the operating means during the execution of the autofocus operation, and a predetermined interrupt occurs during the stop of the autofocus operation. When the execution of the autofocus operation is instructed, the autofocus operation is restarted. Therefore, the autofocus operation is stopped when the operation related to the interrupt is performed, and the execution of the autofocus operation is performed. Until the instruction is issued, the autofocus stop is maintained. Therefore, unlike the prior art, for example, every time a magnification change operation (zoom operation) is performed, the autofocus operation is not restarted, so that an appropriate in-focus position can be obtained without impairing the operational feeling. Can be detected.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a cross-sectional view schematically showing a schematic configuration of an electronic camera including an autofocus device according to a first embodiment of the present invention. This electronic camera is a digital single-lens reflex digital camera, and also has a video shooting function and a display function.

In FIG. 1, the camera CM includes a camera body CB and a photographic lens CL that is replaceably attached to the camera body CB. A finder portion FD is integrally fixed to the upper portion of the camera body CB. However, the photographing lens CL may be integrally fixed to the camera body CB.

An imaging element 20 such as a CCD or CMOS is attached inside the camera body CB. The image sensor 20 converts an image of a subject formed on the imaging surface into an image signal and outputs the image signal. Although not shown, a known mechanical shutter is also provided on the front surface of the image sensor 20.

The viewfinder unit FD is an optical viewfinder for observing an optical image of a subject formed through the photographing lens CL, a quick return mirror 70 described later, and the like. The focusing screen 25, the pentaprism 30, the photometric element 40, A lens 50, an eyepiece 60, and the like are provided.

Note that an image display monitor (not shown) including a liquid crystal panel capable of displaying a through image based on the output signal of the image sensor 20 is provided on the back surface of the camera body CB. Here, the through image is an image captured at a predetermined sampling interval by the image sensor 20 (this sampling interval is an interval that is continuously visible to the human eye) and is displayed on the image display monitor. It is an image used for.

In the camera body CB, the quick return mirror 7 is provided on the front side of the image sensor 20.
0 is pivotally supported. Back side of the main mirror of the quick return mirror 70 (
A sub mirror 80 is integrally attached to the image sensor 20 side.

Part of the light transmitted through the half mirror portion of the main mirror is reflected by the sub mirror 80. The light reflected by the sub-mirror 80 is further reflected by the mirror 90 and enters the AF detection element 100 using a known phase difference detection method.

Although not shown in the figure, an operation unit such as various switches, push buttons, dials, cross keys and the like for manual input of mode settings and other instruction contents is arranged on the upper or rear surface of the camera body CB. ing.

Among the operation units, as the main switches related to the AF operation, a phase difference AF switch 92, a contrast AF switch 94, a focus preset switch 96, an AF lock switch 98, and the like are provided. While the phase difference AF switch 92 is being pressed, the phase difference AF is executed based on the detection value of the phase difference detection AF detection element 100 while the quick return mirror 70 is in the mirror down state.

When the contrast AF switch 94 is pressed, the quick return mirror 70 is switched to the mirror-up state, and while the contrast AF switch 94 is pressed, the contrast AF is executed based on the image signal detected by the image sensor 20. Is done. The phase difference AF switch 92 and the contrast AF switch 94 are switches that are kept on when the photographer continues to be pressed and turned off when the press is released.

When the focus preset switch 96 is pressed, the focus adjustment lens 210c is positioned and driven to a predetermined position (preset position). The preset position is a position arbitrarily set by the photographer. For example, when the photographer focuses on a specific subject, the focus adjustment lens 210c is positioned at a desired position, and a memory switch (not shown) or the like is set at that time. By turning on, the position of the focus adjustment lens 210c at that time is stored in the memory as a preset position. When the AF lock switch 98 is turned on, the operation of the focus adjustment lens 210c is stopped, and the focus adjustment lens 210c remains stationary regardless of the output of any signal from the phase difference AF or contrast AF while it is on.

The photographing lens CL is a photographing optical system for forming an image of a subject on the light receiving surface of the image sensor 20. The photographing lens CL includes a fixed lens 210a, a focal length adjustment lens (zoom lens) 210b, a focus adjustment lens (focus lens) 210c, and a lens barrel 200.
And a fixed lens 210d. The focal length adjustment lens 210b and the focus adjustment lens 210c are each attached so as to be movable in the direction along the optical axis AX of the photographing lens CL.

In general, the focal length adjusting lens 210b changes the position in the direction of the optical axis AX when the photographer manually rotates a zoom ring (not shown) or the like, and changes the focal length of the photographing lens CL accordingly. It can be done. The position of the focal length adjustment lens 210b is detected (monitored) by the zoom encoder 220. The detection value of the zoom encoder 220 is supplied to the focal length change detection unit 340.

In the AF mode in which the focus adjustment lens 210c performs phase difference AF or contrast AF,
Based on the lens drive signal from the lens drive unit 370, the position in the direction along the optical axis AX is changed by the focus adjustment lens drive motor (actuator) 240, and the change in the position is detected (monitored) by the focus adjustment lens position encoder 230. ). Also,
The focus adjustment lens 210c can change the position in the optical axis AX direction by an operator manually turning a focus ring (not shown), and the change in the lens position in this case is also the focus adjustment lens position encoder. 230 (detection).
The detection value by the focus adjustment lens position encoder 230 is supplied to the MF interrupt detection unit 350.

The diaphragm 250 is a variable aperture diaphragm for adjusting the amount of light incident on the image sensor 20, and the diaphragm setting may be performed automatically by the camera or manually by the photographer. The aperture value is determined based on the output of the photometric element 40 in the program mode or the shutter speed priority mode. In the aperture priority mode or the manual mode, it is manually set by the photographer. The operation of the diaphragm 250 is controlled by an unillustrated diaphragm control motor or the like based on the diaphragm value set automatically or manually.

The AF control unit 360 includes a defocus amount calculation unit 310 and a contrast AF area setting unit 3.
20, focus evaluation value calculation unit 330, focal length change detection unit 340, MF interrupt detection unit 350
The processing device constitutes a control system in cooperation with the lens driving unit 370 and the like, and executes a main part of control processing for AF operation described later.

The defocus amount calculation unit 310 calculates a shift amount (defocus amount) between the focal plane and the image pickup surface of the image pickup device 20 from the output of the phase difference AF detection element 100 and supplies it to the AF control unit 360.

In the contrast AF area setting unit 320, the position and size of the contrast detection area, which is a partial area in the imaging area, used for calculating the focus evaluation value in contrast AF,
It is set based on a photographer's operation. The setting contents of the contrast AF area setting unit 320 are supplied to the focus evaluation value calculation unit 330 and the AF control unit 360.

The focus evaluation value calculation unit 330 calculates the focus evaluation value of the portion corresponding to the contrast detection area in the image signal output from the image sensor 20 and supplies the calculation result to the AF control unit 360. As a method of calculating the focus evaluation value in the focus evaluation value calculation unit 330, a method of performing high-frequency component enhancement filter processing on an image and integrating the results can be used. However,
Of course, other methods may be used as the method for calculating the focus evaluation value. The focal length change detection unit 340
When the output from the zoom encoder 220 is changed, that is, when the focal length is changed, information indicating the fact is supplied to the AF control unit 360.

An MF (manual / focus) interrupt detection unit 350 detects the presence or absence of an MF interrupt, that is, whether or not a manual focus adjustment operation has been performed from the outputs of the focus adjustment lens position encoder 230 and the lens driving unit 370. . For example, when the lens driving signal is not output from the lens driving unit 370 to the focus driving motor 240 but the output of the focus adjustment lens position encoder 230 is changed, or when the lens driving signal and the encoder are changed. When there is a difference of a predetermined amount or more in the movement amount based on the output from 230, it is determined that an MF interrupt has occurred, and information indicating that is supplied to the AF control unit 360.

The lens driving unit 370 sets a lens driving amount based on a control signal from the AF control unit 360 and sends a driving signal to the focus adjustment driving motor 240 to move the focus adjustment lens 210c to the optical axis A.
Move in the direction along X.

The AF control unit 360 executes an AF operation related to the phase difference AF and contrast AF according to a predetermined algorithm defined in the control program. The AF control unit 360 uses the phase difference A
When F is executed, the focus adjustment lens driving motor 240 is driven via the lens drive unit 370 based on the output (defocus amount) from the defocus calculation unit 310 to focus the focus adjustment lens 210c. Move to position.

The AF control unit 360 also performs the lens driving unit 370 when performing contrast AF.
The focus adjustment lens drive motor 240 is driven via the lens, the focus adjustment lens 210c is moved to a predetermined start position according to the algorithm, and the focus adjustment lens 210c is moved stepwise from the start position. The focus evaluation value calculated by the focus evaluation value calculation unit 330 based on the image signal from the image sensor 20 is accumulated and held. Then, the position where the focus evaluation value is maximized is calculated using a predetermined mathematical interpolation formula or the like, and this is used as the focus position, and the focus adjustment lens 2
10c is moved to the in-focus position.

(Contrast AF operation)
Next, the contrast AF operation executed by the AF control unit 360 will be described. FIG. 2 is a diagram for explaining a normal operation of contrast AF. As shown in the figure, the contrast AF is composed of three stages of initial drive, search drive, and focus drive. In the figure, the vertical axis indicates the position of the focus adjustment lens 210c, and the horizontal axis indicates time. Further, in the figure, each arrow indicates the movement of the focus adjustment lens 210c, and the tip portion of the arrow is a position where an image signal for obtaining a focus evaluation value is read out. In the following description, when simply referred to as an AF operation, it is assumed that the AF operation is based on contrast AF.

This AF operation is started when the photographer turns on the contrast AF switch 94. When the contrast AF switch 94 is turned on, initial driving is first performed.
This initial drive is a stage in which the focus adjustment lens 210c is positioned and moved to a step movement start position described later. This start position is a position determined in accordance with an algorithm of contrast AF operation, and there are cases where the position is different every time the AF operation is started and cases where the position is always the same.

In this embodiment, a position that satisfies a predetermined condition of “a position that is a predetermined amount away from the current position” of the focus adjustment lens 210c is set as a start position. Accordingly, the start position in this case changes depending on the current position of the focus adjustment lens 210c at the start of the AF operation. On the other hand, when the start position is always the same position (fixed position) regardless of the current position of the focus adjustment lens 210c at the start of the AF operation, the start position is within the movable range (stroke) of the focus adjustment lens 210c. For example, it can be set at the end (stroke end) on the infinity side or the end (stroke end) on the close side of the photographing lens CL.

In the search drive performed after the initial drive, the focus adjustment lens 210c is moved stepwise from the start position by a predetermined drive amount (step width), and the focus is based on the image signal from the image sensor 20 at that position. In this step, the evaluation value is calculated, and the step movement and the focus evaluation value are sequentially repeated in the same manner, and the focus position is calculated and determined based on these focus evaluation values. This operation is performed until the in-focus position is determined or it is determined that the in-focus position cannot be detected.

The focus drive performed after the search drive is a stage where the focus adjustment lens 210c is positioned and moved to the focus position when the focus position is determined in the search drive. Thereby, one AF operation is completed.

Next, regarding the operation when the contrast AF switch 94 is turned off by the photographer and the contrast AF switch 94 is subsequently turned on during the execution of the AF operation described above, the AF operation is stopped by turning off the contrast AF switch 94. A description will be given separately for a case where a predetermined interruption occurs and a case where no interruption occurs.

Here, the predetermined interruption occurs when an operation or the like affecting the focus evaluation value is performed by the photographer during the AF operation, and in this embodiment, the interruption occurs in the following cases. It shall be.

(1) Manual focus adjustment operation (2) Operation change from auto focus mode to manual focus mode (3) Shooting magnification change operation (4) Aperture change operation (5) Focus detection area change operation (6) Focus Lock operation (7) Focus preset operation (8) Elapse of a predetermined time or more of the stop time Here, (1) manual focus adjustment operation means that the photographer manually turns the focus ring to change the position of the focus adjustment lens 210c. An operation to change and adjust. Since the focus adjustment lens 210c is moved, the operation is highly likely to affect the focus evaluation value. Whether or not this operation has been performed is detected by the MF interrupt detection unit 350 as described above, and AF
The control unit 360 is notified.

(2) The change operation from the auto focus mode (AF mode) to the manual focus mode (MF mode) means that the operator performs a predetermined mode selection operation for changing from the AF mode to the MF mode. That is, an operation for instructing the release of the AF mode. Note that the series of AF operations described here are performed only when the AF mode is set, and are not performed in the MF mode.

(3) The photographing magnification changing operation is an operation in which the photographer manually turns the zoom ring to change and adjust the position of the focal length adjustment lens 210b. Operations that may affect the focus evaluation value because the size of the subject in the focus detection area, which is a part of the shooting area used to calculate the focus evaluation value, changes due to the change in the shooting magnification. It is. Whether or not this operation has been performed is detected by the focal length change detection unit 340 as described above, and the AF control unit 36.
0 is notified.

(4) The aperture changing operation is a predetermined operation performed by the photographer to change the aperture value.
The aperture diameter of the diaphragm 250 of the photographic lens CL is adjusted so that the diaphragm value set by this operation is obtained. Since the brightness of the image of the subject is changed by changing the aperture, the focus evaluation value is highly likely to change greatly. In the case of a camera of a type in which the aperture diameter of the diaphragm 250 can be changed manually, this means manual operation of the diaphragm.

(5) The operation for changing the focus detection area is an operation for changing the size and / or position of the focus detection area, which is a partial area used for calculating the focus evaluation value in the imaging area. Further, the operation is to change the contents set in the contrast AF area setting unit 320. Since the relative relationship of the focus detection area with respect to the subject image is changed, this operation is highly likely to affect the focus evaluation value.

(6) The focus lock operation is an operation for fixing the focus adjustment lens 210c at the current position, and is an operation for turning on the AF lock switch 98 described above. If this operation is performed, there is a high possibility that an operation for changing the composition will be performed, and the image in the focus detection area will be different, so this operation is highly likely to affect the focus evaluation value. . When the focus lock operation is performed and the difference between the focus evaluation values calculated before and after the focus lock operation is small, it is assumed that the composition has not been changed, and an interrupt may not be generated. .

(7) The focus preset operation is an operation for moving the focus adjustment lens 210c to a predetermined preset position, and is an operation for turning on the focus preset switch 96 described above. Since the position of the focus adjustment lens 210c is changed to the preset position, the operation is highly likely to affect the focus evaluation value.

(8) The elapse of a predetermined time or more of the stop time means that it is detected that a predetermined time or more has elapsed since the contrast AF switch 94 was turned off.
This is determined by the elapsed time measured using a clock (not shown) provided in the F control unit 360. This predetermined time is preferably set to such a short time that no or almost no other interrupt operation can be performed, and can be set to about 1 second, for example.

(AF operation when no interrupt occurs)
FIG. 3 is a time chart for explaining the operation when the contrast AF switch 94 is turned off during the execution of the AF operation and no interruption that affects the focus evaluation value occurs during the OFF operation. FIG. 8 is a diagram for explaining the operation of the focus adjustment lens 210c in this case.

In FIG. 3, first, when the quick return mirror 70 is switched from the mirror-down state to the mirror-up state at the time t1, the output of the through image from the image sensor 20 (
Through image output) starts. Next, at time t2, the contrast AF switch 9
When 4 is turned on, execution of the AF operation is started at the same time. Next, when the contrast AF switch 94 is turned off at time t3, the AF operation is interrupted (stopped).

At this time, the AF operation performed until immediately before the interruption is saved. Specifically, the current position (position at the time of interruption) of the focus adjustment lens 210c, the focus evaluation value that has been calculated so far, and the like are stored and held in a memory (not shown) provided in the AF control unit 360. In addition,
The AF operation is not immediately interrupted when the contrast AF switch 94 at time t3 is turned off, but as described later, until a good break (for example, until the step movement at the time of occurrence of the interrupt is completed). The AF operation may be interrupted after the operation is continued.

Next, when the contrast AF switch 94 is turned on again at time t4, the AF operation is executed again, but the contrast AF switch 94 is being turned off (
In the figure, since no interruption has occurred during the period from time t3 to time t4), the AF operation is continued from the position at which the focus adjustment lens 210c is interrupted (hereinafter sometimes referred to as the interruption position). . That is, the AF operation performed during the period from time t2 to time t3 and the AF operation performed after time t4 are continuous processes. Therefore, in this case, the focus position is determined using the focus evaluation value already calculated before the interruption and the focus evaluation value calculated after the restart.

The movement of the focus adjustment lens 210c in this case is shown in FIG. In the figure, the vertical axis indicates the position of the focus adjustment lens 210c, and the horizontal axis indicates time. Further, in the figure, each arrow indicates the movement of the focus adjustment lens 210c, and the tip portion of the arrow is a position where an image signal for obtaining a focus evaluation value is read out. However, this figure shows the time t3 when the contrast AF switch 94 is turned off in order to smooth the flow when the AF operation is interrupted and resumed.
In this case, the AF operation is not interrupted immediately, but pre-interruption processing is performed in which the AF operation is continued until a time point t3 ′ with a good break, and the AF operation is interrupted when the pre-interruption processing is completed.

When the contrast AF switch 94 is turned on at time t2, initial driving is performed.
Next, search driving is performed. During the search drive, the contrast AF switch 94 is turned off at time t3, and at that time t3, the focus adjustment lens 210c is stepping (driving the focus adjustment lens 210c to obtain the next focus evaluation value). In this case, the AF operation is interrupted at time t3 ′ when the step movement is completed. Due to this interruption, the focusing lens 2
The movement of 10c is stopped at that time, and the state is maintained during the off state. Here, the focus evaluation value at the position after the step movement is calculated when the focus adjustment lens 210c is stopped. However, the calculation may not be performed.

Thereafter, when the contrast AF switch 94 is turned on again at time t4, the search drive is resumed from the same position as that at the time of the interruption. Step movement and calculation of the focus evaluation value are repeated until the in-focus position is detected. If the in-focus position is detected at time t5, in-focus driving is performed, and the focus adjustment lens 210c is moved to the in-focus position. Is moved to position.

As described above, when the contrast AF switch 94 is turned off during the execution of the AF operation, and no interruption that affects the focus evaluation value occurs during the turning-off, the time t3 (or t3 ′) is interrupted. Since the position of the focusing lens 210c does not change between the time point t4 and the time point t4 when the time t4 is resumed, the remaining operation that should have been executed without the interruption from the time point t3 (or t3 ′) when the AF operation is interrupted. There is no problem even if the operation is continuously executed from the restart time point t4, so that the AF operation can be completed quickly and the operability can be improved.

By the way, the contrast AF switch 94 is kept on by being pressed down, and is turned off when the press is released. Therefore, even if the photographer does not intend to stop the AF operation, the contrast AF switch 94 is kept in a short time. It is possible to make a so-called inadvertent mistake that cancels the pressing. In such a case, when the AF operation is resumed, it is preferable to continue the AF operation from the state at the time of interruption from the viewpoint of quick completion of the AF operation and operability.

In this embodiment, as described above, as one of the causes of the interruption, an elapse of a predetermined time or more of the stop time is set. This is performed after the contrast AF switch 94 is turned off during the AF operation. If the contrast AF switch 94 is turned on within a time (for example, within 1 second), it means that an interrupt related to the elapse of the predetermined time of the stop time does not occur, and an interrupt related to other operations occurs. If not, the AF operation is performed when the above-described interruption has not occurred. Even if such an accident is made, the AF operation can be quickly performed without impairing the operability. Can be completed.

(AF operation when an interrupt occurs)
FIG. 5 is a time chart for explaining the operation when the contrast AF switch 94 is turned off during the execution of the AF operation, and an interrupt that affects the focus evaluation value occurs during the OFF operation. It is a figure for demonstrating operation | movement of the focus adjustment lens 210c.

In FIG. 5, first, when the quick return mirror 70 is switched from the mirror-down state to the mirror-up state at time t1, output of a through image from the image sensor 20 is started. Next, when the contrast AF switch 94 is turned on at time t2,
At the same time, execution of the AF operation is started. Next, at time t3, contrast A
When the F switch 94 is turned off, the AF operation is interrupted (stopped). Up to this point, the process is the same as in FIG.

Next, when the contrast AF switch 94 is turned on again at time t4, the AF operation is executed again, but the contrast AF switch 94 is being turned off (
Since an interrupt has occurred during the period from time t3 to time t4), in this case, the AF operation is restarted from the beginning. In this case, “redo” means that the focus adjustment lens 210c is moved to a start position satisfying a predetermined condition (here, a position satisfying a predetermined condition of “a position away from the current position by a predetermined amount” of the focus adjustment lens 210c). This means that an AF operation is newly started from that position regardless of the AF operation before the interruption. Therefore, in this case, the focus evaluation value already calculated before the interruption is discarded, and the focus position is determined using only the focus evaluation value calculated after the restart.

The movement of the focus adjustment lens 210c in this case is shown in FIG. In the figure, the vertical axis indicates the position of the focus adjustment lens 210c, and the horizontal axis indicates time. Further, in the figure, each arrow indicates the movement of the focus adjustment lens 210c, and the tip portion of the arrow is a position where an image signal for obtaining a focus evaluation value is read out. However, this figure shows the time t3 when the contrast AF switch 94 is turned off in order to smooth the flow when the AF operation is interrupted and resumed.
In this case, the AF operation is not interrupted immediately, but the pre-interruption processing is performed in which the AF operation is continued until a good break, and the AF operation is interrupted at time t3 ′ when the pre-interruption processing is completed.

First, when the contrast AF switch 94 is turned on at time t2, initial driving is performed, and the focus adjustment lens 210c is positioned at a position P2 away from the current position P1 by a predetermined amount (a position away from the current position P1 by a predetermined amount). Are moved to a position P2) that satisfies the predetermined condition. Next, search driving is performed. During the search drive in which the step movement and the calculation of the focus evaluation value are repeated, the contrast AF switch 94 is turned off at time t3, and at that time t3, the focus adjustment lens 210c is stepping (obtaining the next focus evaluation value). Therefore, when the focus adjustment lens 210c is being driven), the AF operation is interrupted at time t3 ′ when the movement to the position P3 of the step movement destination is completed.

Due to this interruption, the movement of the focus adjustment lens 210c is stopped at the time t3 ′, and the state is maintained during the OFF state. Here, at the time t when the focusing lens 210c is stopped.
3 ′, the focus evaluation value at the position P3 after the step movement is calculated.
The calculation may not be performed. Thereafter, when the contrast AF switch 94 is turned on again at time t4, the AF operation is restarted. In this case, initial driving is performed again.

In the initial driving in the AF operation after the resumption, the starting position of the focus adjustment lens 210c is the current position of the focus adjustment lens 210c at the time t4, that is, the position P4 that is a predetermined amount away from the position P3 (from the current position P3). This position is a position P4) that satisfies a predetermined condition of a position that is separated by a fixed amount. Accordingly, the start position P4 after the AF operation is resumed is the start value P2 before the interruption.
Is usually different. However, the start position after the restart may be made to coincide with the start position P2 before the interruption. On the other hand, as in this embodiment, the position at which the focus adjustment lens 210c satisfies the predetermined condition of “a position away from the current position by a predetermined amount” is not set as the start position, but the stroke end at the infinity side or the close side. Is set as the start position (fixed start position / predetermined start position), the start position before the AF operation is interrupted and after the restart is always the same. Next, until the in-focus position is detected, search driving is performed in which the step movement and the calculation of the focus evaluation value are repeated. If the in-focus position is detected during this time, the in-focus driving is performed.

As described above, when the contrast AF switch 94 is turned off during the execution of the AF operation and an interrupt that affects the focus evaluation value occurs during the OFF operation, a new one is made regardless of the AF operation before the interruption. Since the AF operation is performed again, the focus evaluation value obtained before the interruption is also used even though the focus evaluation value obtained before the interruption and the focus evaluation value obtained after the restart are not related. Thus, it is possible to prevent false focusing without calculating the focus position.

By the way, the contrast AF switch 94 is kept on by being pressed down, and is turned off when the press is released. Therefore, even if the photographer does not intend to stop the AF operation, the contrast AF switch 94 is kept in a short time. The so-called inadvertent mistake that releases the press can occur as described in the operation when there is no interrupt. However, on the other hand, if the stop time is not short, it can be estimated that the AF operation has been stopped with the intention of changing the subject and shooting conditions, and there is a high probability that an operation that affects the focus evaluation value will be performed. Here, as one of the causes of the interruption, the elapse of a predetermined time or more of the stop time is set. This is after the contrast AF switch 94 is turned off during the AF operation and after a predetermined time elapses (for example, 1 second). This means that an interrupt occurs after the elapse of time), and when the predetermined time has elapsed, the AF operation when the above-described interrupt occurs is performed. Therefore, even in such a case, it is possible to effectively prevent false focusing.

[Second Embodiment]
The processing in the first embodiment described above is performed when the AF operation is restarted depending on whether or not an interrupt that affects the focus evaluation value occurs while the contrast AF switch 94 is off, that is, when the AF operation is stopped (interrupted). The process of whether to continue from the point of interruption or to start over from the beginning is switched. In contrast, the processing in the second embodiment is as follows.
Processing of whether to continue from the point of interruption or to start over from the beginning when the AF operation is restarted depending on whether an interrupt that affects the focus evaluation value occurs while the contrast AF switch 94 is on, that is, during the AF operation Is switched.

Since the configuration of the camera and the cause of interruption in the second embodiment are the same as those in the first embodiment described above, description thereof will be omitted. In addition, the operation in the case where no interrupt occurs in the second embodiment is the same as the operation described with reference to FIGS. 3 and 4 in the first embodiment described above, except that the time of occurrence of the interrupt is different. Therefore, the description is also omitted.

(AF operation when the AF switch is turned off during interruption)
FIG. 7 shows an interrupt that affects the focus evaluation value during execution of the AF operation, that is, while the contrast AF switch 94 is on, and the contrast AF switch 9 during the interruption.
6 is a time chart for explaining an operation when 4 is turned off.

In FIG. 7, first, when the quick return mirror 70 is switched from the mirror-down state to the mirror-up state at the time t1, the output of the through image from the image sensor 20 (
Through image output) starts. Next, at time t2, the contrast AF switch 9
When 4 is turned on, execution of the AF operation is started at the same time.

Next, if an interrupt occurs at the time t2 ′ during execution of this AF operation, the AF operation is interrupted (stopped) regardless of whether the contrast AF switch 94 is on.
Is done. At this time, the AF operation performed until immediately before the interruption is saved. Specifically, the current position (position at the time of interruption) of the focus adjustment lens 210c, the focus evaluation value that has been calculated so far, and the like are stored in a memory (storage unit) (not shown) provided in the AF control unit 360. Is done. In this case as well, as in the first embodiment described above, the AF operation is not stopped immediately when an interrupt at time t2 ′ occurs, but until a break (for example, when the interrupt occurs) The AF operation may be interrupted after the operation is continued (until the step movement according to the above is completed).

Next, the contrast AF switch 94 is turned off at the time t3, but the interruption is continuing, and the interruption ends at the time t3 ". After that, at the time t4,
When the contrast AF switch 94 is turned on again, the AF operation is executed again. However, an interrupt is generated while the contrast AF switch 94 is on (period t2 to time t3). Restarts the AF operation from the beginning. In this case, “redo” means that the focus adjustment lens 210c is a start position that satisfies the predetermined condition as described above (here,
This means that the focus adjustment lens 210c is moved to a position separated from the current position by a predetermined amount), and the AF operation is started again from that position regardless of the AF operation before the interruption. Accordingly, the focus evaluation value already calculated before the interruption is discarded, and the focus position is determined using only the focus evaluation value calculated after the restart.

As described above, while the AF operation is being performed, that is, while the contrast AF switch 94 is on,
When an interrupt that affects the focus evaluation value occurs, the AF operation is newly executed regardless of the AF operation before the interruption. Therefore, the focus evaluation value obtained before the interruption and the value obtained after the restart are obtained. The focus position is not calculated using the focus evaluation value obtained before the interruption even though the focus evaluation value obtained is not related, and an appropriate focus position can be obtained. Is possible.

Further, since the contrast AF switch 94 is turned off at the time t3 ″ when the interruption ends, the AF operation is not resumed at this time t3 ″, and the time t4 when the contrast AF switch 94 is turned on. Thus, the AF operation is started again from the beginning. Therefore, even when an interruption operation (for example, a zoom operation) is frequently performed, the AF operation is not frequently restarted, and the operational feeling can be improved.

(AF operation when AF switch is turned off after completion of interrupt)
FIG. 8 shows an interrupt that affects the focus evaluation value during execution of the AF operation, that is, while the contrast AF switch 94 is on. After the interruption, the contrast AF switch 9
6 is a time chart for explaining an operation when 4 is turned off.

In FIG. 8, first, when the quick return mirror 70 is switched from the mirror-down state to the mirror-up state at the time t1, the output of the through image from the image sensor 20 (
Through image output) starts. Next, at time t2, the contrast AF switch 9
When 4 is turned on, execution of the AF operation is started at the same time.

Next, if an interrupt occurs at the time t2 ′ during execution of this AF operation, the AF operation is interrupted (stopped) regardless of whether the contrast AF switch 94 is on.
Is done. At this time, the AF operation performed until immediately before the interruption is saved. Specifically, the current position (position at the time of interruption) of the focus adjustment lens 210c, the focus evaluation value that has been calculated so far, and the like are stored in a memory (storage unit) (not shown) provided in the AF control unit 360. Is done. In this case as well, as in the first embodiment described above, the AF operation is not stopped immediately when an interrupt at time t2 ′ occurs, but until a break (for example, when the interrupt occurs) The AF operation may be interrupted after the operation is continued (until the step movement according to the above is completed).

Next, the interrupt is terminated at the time t3 ″, but at the time t3 ″, the contrast AF switch 94 is kept on, and at the time t3 after the time t3 ″ when the interrupt operation is terminated. Then, the contrast AF switch 94 is turned off, and then the contrast AF switch 94 is turned on again at time t4, so that the AF operation is performed again. (period of t3)
Since an interrupt has occurred, in this case, the AF operation is restarted from the beginning. “Redo” in this case means that the focus adjustment lens 210c is moved to a start position satisfying a predetermined condition (here, a position away from the current position of the focus adjustment lens 210c by a predetermined amount), and the AF before the interruption is performed from that position. This means that a new AF operation is started regardless of the operation. Therefore, in this case, the focus evaluation value already calculated before the interruption is discarded, and the focus position is determined using only the focus evaluation value calculated after the restart.

As described above, while the AF operation is being performed, that is, while the contrast AF switch 94 is on,
When an interrupt that affects the focus evaluation value occurs, the AF operation is newly executed regardless of the AF operation before the interruption. Therefore, the focus evaluation value obtained before the interruption and the value obtained after the restart are obtained. Although the focus evaluation value obtained is not related, the focus position is not calculated using the focus evaluation value obtained before the interruption, and false focus can be prevented. .

Further, the contrast AF switch 94 remains on at the time point t3 "when the interruption ends, but the AF operation is not resumed at this time point t3", and until the contrast AF switch 94 is turned on after being turned off. AF operation is not resumed. Accordingly, the AF operation is restarted each time the zoom operation is performed even when the operation related to the occurrence of the interruption (for example, the zoom operation) is frequently performed while the contrast AF switch 94 is kept on. The troublesomeness is eliminated and the operational feeling can be improved.

In each of the above-described embodiments, the “starting position that satisfies the predetermined condition” is described as indicating a position that is a predetermined amount away from the current position. However, the fixed position described above (for example, a predetermined position such as a slot talk end) is described. The AF process may be performed with the position) as a start position that satisfies a predetermined condition.

The embodiment described above is described in order to facilitate understanding of the present invention, and
It is not described to limit the invention. Therefore, each element disclosed in the above embodiment includes all design changes and equivalents belonging to the technical scope of the present invention.

It is a figure which shows schematic structure of the camera of 1st Embodiment of this invention. It is a figure for demonstrating normal AF operation | movement of 1st Embodiment of this invention. 6 is a time chart for explaining the operation when the AF switch is turned off during the execution of the AF operation of the first embodiment of the present invention and no interruption that affects the focus evaluation value occurs during the off operation. . It is a figure for demonstrating operation | movement of the focus adjustment lens in the case of FIG. 7 is a time chart for explaining an operation when an AF switch is turned off during execution of an AF operation of the first embodiment of the present invention and an interrupt that affects the focus evaluation value occurs during the off operation. It is a figure for demonstrating operation | movement of the focus adjustment lens in the case of FIG. FIG. 6 is a time chart for explaining the operation when an interrupt that affects the focus evaluation value occurs during the execution of the AF operation of the second embodiment of the present invention and the AF switch is turned off while the interrupt continues. is there. 10 is a time chart for explaining an operation when an interrupt that affects the focus evaluation value occurs during the execution of the AF operation of the second embodiment of the present invention, and the AF switch is turned off after the end of the interrupt. . It is a figure for demonstrating the problem of false focusing.

CM ... Camera, CB ... Camera body, CL ... Shooting lens, FD ... Finder section, 20 ...
Image sensor 70 ... Quick return mirror 94 ... Contrast AF switch 96 ... Focus preset switch 98 ... AF lock switch 210b ... Focal length adjustment lens 210c ... Focus adjustment lens 220 ... Zoom encoder 230 ... Focus adjustment lens Position encoder, 240 ... focus adjustment lens drive motor, 250 ... stop, 320 ... contrast AF area setting unit, 330 ... focus evaluation value calculation unit, 340 ... focal length change detection unit, 350
... MF interrupt detection unit, 360 ... AF control unit, 370 ... Lens drive unit.

Claims (5)

An operation unit for operating or stopping the autofocus operation;
And a control unit which performs seek control to acquire an evaluation value by driving the focusing lens,
The control unit changes the photographing magnification when performing the search control for driving the focus adjustment lens in the first direction even if the operation of the autofocus operation by the operation unit is continued. When the operation is performed, the search control is stopped until an execution operation is performed after the operation of stopping the autofocus operation by the operation unit, and the operation for changing the photographing magnification is finished after the search control is stopped. When the operation unit performs an operation after stopping the autofocus operation, the focus adjustment lens is driven to a predetermined position, and then the focus adjustment lens is driven in the first direction. To obtain the evaluation value,
The focus adjustment device, wherein the predetermined position is a position away from the position of the focus adjustment lens when the search control is stopped to the side opposite to the first direction. The focus adjustment device according to claim 1, comprising:
The predetermined position is a position between a start position of the search control before the photographing magnification changing operation is performed and a position of the focus adjustment lens when the search control is stopped. Focusing device. The focus adjusting apparatus according to claim 1 or 2,
The focus adjustment apparatus, wherein the control unit performs the search control and a focus drive control for driving the focus adjustment lens to a focus position determined based on the evaluation value. The focus adjustment device according to any one of claims 1 to 3 ,
When the search control before the photographing magnification change operation and the search control after the photographing magnification change operation are performed, the control unit performs the photographing magnification change operation. And determining the in-focus position without using the evaluation value obtained by the search control before the photographing magnification changing operation is performed using the evaluation value obtained by the search control after Focus adjustment device characterized by. An imaging apparatus comprising the focus adjustment apparatus according to any one of claims 1 to 4 .

Images