JP2003005018A - Focus detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stop driving a focusing lens through focus detection processing for a specific time after optical zooming operation ends. SOLUTION: A zoom lens 2 varies the field angle of a lens unit 1. The focusing lens 3 adjusts a focusing position. A zoom lens 4 drives the zoom lens 2 to move forward and backward along the optical axis. A zoom motor driver 5 outputs a driving signal to the zoom motor 4. A focusing motor 6 drives the focusing lens 3 to move forward and backward along the optical axis. A focusing motor driver 7 outputs a driving signal to the focusing motor 6. An image pickup element 10 picks up a subject image and outputs an image pickup signal. A focus evaluated value computing element 9 computes a focus evaluated value from the image pickup signal used for focus detection. A focusing control part 8 outputs a focusing lens driving command so that the focus evaluated value is maximized. The focusing control circuit 8 inhibits the focusing motor 6 from being driven until a counted value counted after the completion of zoom operation exceeds a threshold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus detecting device for a camera having an optical zoom function.

[0002]

2. Description of the Related Art There is known a focus detecting device for picking up an image of a subject using an image pickup device such as a CCD and detecting an adjustment state of a focus position by a photographing lens based on an image pickup signal output from the image pickup device. Among them, the focus detection method called the hill climbing method is the data of the high frequency component of the frequency of the image pickup signal while moving the photographing lens back and forth with respect to the focus position, that is, the focus position is set so as to maximize the focus evaluation value. To detect. According to this method, the driving of the photographic lens is not stopped in the defocused state, so that the followability with respect to changes in the captured image is improved.

[0003]

However, the hill-climbing focus detection device cannot refer to the focus evaluation value before the change when a large change occurs in the captured image. For this reason, even if the taking lens is in focus, the taking lens moves greatly from the in-focus position when a large change occurs in the taken image. In particular, during the zoom operation, the image pickup signal continues to change due to the change in the angle of view of the captured image, so that it becomes difficult to detect the focus adjustment state until the zoom operation is completed.

It is an object of the present invention to provide a focus detection device which stops driving of a photographing lens for focus detection during a zoom operation.

[0005]

FIG. 1 showing an embodiment.
The present invention will be described in association with. (1) The focus detection device according to the invention described in claim 1 is an evaluation in which a focus evaluation value is calculated using an image pickup device 10 that picks up a subject image through the photographing zoom lens 1 and an image pickup signal output from the image pickup device 10. A value calculation circuit 9, drive signal output circuits 8 and 7 for outputting a drive signal for driving the photographing zoom lens 1 so as to maximize the focus evaluation value calculated by the evaluation value calculation circuit 9, and the photographing zoom lens 1 Operation signal detection circuit 8 for detecting a zoom operation signal for changing the angle of view of the drive signal, and a drive signal output circuit for prohibiting the output of the drive signal for a predetermined time when the operation signal detection circuit 8 detects the operation signal. The above-mentioned object is achieved by including the control circuit 8 for controlling the control units 8 and 7. (2) The invention according to claim 2 is the focus detection apparatus according to claim 1, wherein the control circuit 8 includes an operation signal detection circuit 8
It is characterized in that the time during which the output of the drive signal is prohibited is changed in accordance with the time during which the operation signal is continuously detected. (3) The invention according to claim 3 is the focus detection device according to claim 2, wherein the control circuit 8 includes an operation signal detection circuit 8
When the operation signal is detected again immediately after the operation signal is no longer detected by, the time for inhibiting the output of the drive signal is changed.

In the section of means for solving the above-mentioned problems, the present invention is limited to the embodiments although it is associated with the drawings of the embodiments in order to explain the present invention in an easy-to-understand manner. is not.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First Embodiment FIG. 1 is a block diagram showing the outline of a focus detection device for an autofocus camera according to the first embodiment of the present invention. 1, the autofocus camera includes a lens unit 1, a zoom motor 4, a zoom motor driver 5, a focus motor 6, a focus motor driver 7, a focus control circuit 8, and a focus evaluation value calculator 9. ,
The imaging device 10, the release switch 11, the zoom operation switch 12, and the timer circuit 13 are included.

The lens unit 1 includes a zoom lens 2 and a focus lens 3. The zoom lens 2 is a lens that changes the focal length of the lens unit 1 to change the angle of view and changes the magnification of the subject image. Focus lens 3
Is an image sensor 1 that captures a subject image that has passed through the lens unit 1.
It is a lens that adjusts the focal position so that an image is formed on the image plane of 0. The zoom motor 4 drives the zoom lens 2 forward and backward in the optical axis direction. The zoom motor driver 5 generates and outputs a drive signal for the zoom motor 4. The focus motor 6 drives the focus lens 3 forward and backward in the optical axis direction. The focus motor driver 7 generates and outputs a drive signal for the focus motor 6.

The image pickup device 10 picks up a subject image that has passed through the lens unit 1 and outputs an image pickup signal corresponding to each pixel. The image pickup signal output corresponding to each pixel of the image pickup device 10 has a different signal level according to the intensity of light incident on each pixel. The focus evaluation value calculator 9 is the image sensor 1
Of the image pickup signals output from 0, a high frequency component is extracted from the image pickup signal used for focus detection to calculate a focus evaluation value. Specifically, a focus evaluation value is obtained by extracting a desired frequency component from the image pickup signal by passing the image pickup signal through a bandpass filter and integrating the absolute value of the extracted signal.
FIG. 2 is a diagram showing an example of the relationship between the position of the focus lens 3 and the focus evaluation value. In FIG. 2, the horizontal axis represents the position of the focus lens 3, and the vertical axis represents the focus evaluation value.
The position P that maximizes the focus evaluation value is the focus lens 3
Is the in-focus position.

The focus control circuit 8 maximizes the focus evaluation value calculated by the focus evaluation value calculator 9, that is, eliminates the blurring of the edge of the subject image picked up by the image pickup device 10 to increase the contrast. To maximize
A focus lens drive command is output to the focus motor driver 7. The focus control circuit 8 drives the focus lens 3 in the infinity direction in FIG. 2 to drive the focus lens 3 in the ∞ direction when the focus evaluation value decreases. Also,
The focus control circuit 8 drives the focus lens 3 in the infinity direction when the focus evaluation value decreases by driving the focus lens 3 in the ∞ direction. That is, the focus lens 3 is alternately driven in the close-up direction and the ∞ direction with the position (focus position) at which the focus evaluation value is maximized sandwiched.

The focus control circuit 8 receives a zoom operation signal from the zoom operation switch 12, a release operation signal from the release switch 11, and a count signal from the timer circuit 13. The focus control circuit 8 further outputs a zoom lens drive command to the zoom motor driver 5 in response to a zoom operation signal from the zoom operation switch 12. The zoom operation here is an operation for optically changing the zoom magnification.

The focus detection processing by the focus detection device of the autofocus camera described above is called a hill climbing method. In the hill-climbing focus detection process, the focus lens 3 is always driven when the autofocus camera is set to the continuous autofocus (AFC) mode in which the focus detection process is always performed. The present invention is to stop the driving of the focus lens 3 which is always performed by the focus detection processing when the optical zoom operation is performed for a predetermined time.

The autofocus camera according to the first embodiment is provided with a continuous autofocus mode and a single autofocus (AFS) mode. Single autofocus mode,
This is an operation mode in which focus detection is performed only once when the release switch is pressed halfway. The autofocus camera according to the present embodiment is characterized by the operation when it is set in the continuous autofocus mode, and therefore the continuous autofocus mode will be mainly described.

FIG. 3 is a flow chart showing the flow of focus detection processing performed by the focus control circuit 8 of the autofocus camera described above. The program according to the process of FIG. 3 is repeatedly executed by being activated by a command from a main CPU (not shown) of the camera. In step S1, the focus control circuit 8 determines whether or not the camera is set to the continuous autofocus mode based on information from a main CPU (not shown). Focus control circuit 8
Is an affirmative decision in step S1 when the continuous autofocus mode is set, step S
If the single autofocus mode is set, the process proceeds to step S10, and a negative determination is made in step S1 and the process proceeds to step S2.

In step S2, the focus control circuit 8
Sets the count flag to 0 and proceeds to step S3. On the other hand, in step S10, the focus control circuit 8 sets the count flag to 1 and proceeds to step S3. The count flag is a counter flag (not shown) in the focus control circuit 8 that counts a time period during which an AF operation process (focus detection process) described later is prohibited. When the count flag = 1, the counter counts, and when the count flag = 0, the counter does not count. Therefore, if the single autofocus mode is set, step S2
The count flag is set to 0 by
The F operation process (focus detection process) is not prohibited.

In step S3, the focus control circuit 8
Determines whether a zoom operation signal is input from the zoom operation switch 12. If the zoom operation signal is input, it is considered that the zoom is on, and an affirmative decision is made in step S3, and the operation proceeds to step S11. If the zoom operation signal has not been input, a negative decision is made in step S3 and the operation proceeds to step S4.

In step S4, the focus control circuit 8
Determines whether the zoom flag is 0. The zoom flag is a flag that is set to 1 when a zoom operation is performed and is set to 0 when a predetermined time elapses after the zoom operation is not performed. The focus control circuit 8 makes an affirmative decision in step S4 if the zoom flag = 0 to proceed to step S5. In this case, it is considered that a predetermined time or more has elapsed since the previous zoom operation with the zoom operation switch 12 not being operated. In step S5, the focus control circuit 8
Performs the hill-climbing focus detection process described above, outputs a focus lens drive command to the focus motor driver 7, and ends the process shown in FIG.

On the other hand, the focus control circuit 8 uses the zoom flag =
In the case of 1, a negative decision is made in step S4 and the operation proceeds to step S6. In this case, it is considered that the zoom operation switch 12 is not operated and before a predetermined time has elapsed from the previous zoom operation, that is, immediately after the zoom operation is completed. In step S6, the focus control circuit 8 determines whether the count flag is 1. The focus control circuit 8 makes an affirmative decision in step S6 if the counter flag = 1 to proceed to step S7, and in the case of counter flag = 0 the step S6.
Is negatively determined, and the processing in FIG. 3 ends.

In step S7, the focus control circuit 8
Determines whether the count value of the counter (not shown) exceeds the threshold value. The count value is obtained by counting the count signal from the timer circuit 13 input to the focus control circuit 8. The focus control circuit 8 makes an affirmative decision in step S7 if the counter> threshold is true to proceed to step S9, whereas it makes a negative decision in step S7 if the counter> threshold is not true to proceed to step S8.

In step S8, the focus control circuit 8 causes the counter to increment by 1 and ends the processing shown in FIG. In S9, the focus control circuit 8 resets the counter to 0, sets the zoom flag to 0, and ends the processing in FIG.

In step S11 to which the affirmative determination is made in step S3, the focus control circuit 8
The zoom flag is set to 1, the counter is reset to 0, and the process proceeds to step S12. In step S12, the focus control circuit 8 outputs a zoom lens drive command to the zoom motor driver 5 in response to an operation signal from the zoom operation switch 12 to perform zoom control processing. After the zoom control, the process shown in FIG. 3 ends.

The time from when the zoom operation switch 12 is not operated (negative determination in step S3) to when the count value exceeds the threshold value (affirmative determination in step S7) corresponds to the time during which the hill-climbing focus detection processing is prohibited. To do. During this time, the change of the angle of view of the captured image by the zoom operation is completed,
It is determined according to the time required until the change of the image pickup signal from the image pickup device 10 accompanying the change of the angle of view settles down. Note that this time can be changed by changing the threshold value.
In the camera according to the first embodiment, the threshold value is determined so that the time for which the focus detection process is prohibited is several hundred milliseconds.
The determined threshold value is stored in a memory (not shown) in the focus control circuit 8.

In the above description, the focus control circuit 8 prohibits all the hill-climbing focus detection processing until the count value exceeds the threshold value. In this case, all processes for focus detection such as calculation of the focus evaluation value including driving of the focus lens 3 by the focus motor 6 are stopped. Instead of this, the focus motor driver 7
It is also possible to prohibit only the output of the focus lens drive command for. Here, prohibiting the output of the focus lens drive command is stopping the focus motor 6.

According to the first embodiment described above,
The following effects can be obtained. (1) When the autofocus camera is set to the continuous autofocus mode, zoom operation is performed (step S3 is positive), zoom control processing is performed (step S12), and zoom operation is stopped (step S3). When the determination is negative), the drive of the focus motor 6 is prohibited from the end of the operation until the count value exceeds the threshold (affirmative determination in step S7). As a result, when the zoom operation is performed, the drive of the focus lens 3 is stopped, the change of the angle of view of the captured image by the zoom operation is completed, and the drive of the focus lens 3 is resumed after the change of the image pickup signal accompanying the change of the angle of view is stabilized To be done. As a result, the focus lens 3 is not driven in a state where the focus evaluation value is changed and focus detection is difficult, so that power consumption can be suppressed as compared with the case where the focus lens 3 is driven. Further, when displaying an image based on the image pickup signal on an electronic viewfinder or the like, the focus lens 3 is not driven in a state in which focus detection is difficult, so that it is possible to prevent an image in a defocused state from being displayed. (2) Since the drive of the focus motor 6 is not prohibited when the autofocus camera is set to the single autofocus mode, the focus detection processing can be performed at the timing of the half-press operation of the release switch 11. .

In the above description, the focus motor 6 is driven from the input of the zoom operation signal until the count value that starts counting after the input of the zoom operation signal exceeds the threshold value (affirmative determination in step S7). Banned. Alternatively, the drive of the focus motor 6 may be prohibited after the input of the zoom operation signal is completed and before the count value that starts counting at this point exceeds the threshold value.

Second Embodiment In the second embodiment, the time during which the hill-climbing focus detection processing is prohibited is changed according to the time during which the zoom operation switch 12 is operated. The inhibition time is changed by changing the threshold value of the counter. FIG. 4 is a flowchart showing the flow of focus detection processing performed by the focus control circuit 8 of the autofocus camera according to the second embodiment of the present invention.
The program by the processing of FIG. 4 is started by a command from a main CPU (not shown) of the camera and is repeatedly executed, as in the first embodiment. In FIG. 4, step S
The respective processes of 1, step S2, and step S10 are
Since the processing is the same as that described with reference to FIG. 3, description thereof will be omitted.

In step S21, the focus control circuit 8
Determines whether a zoom operation signal is input from the zoom operation switch 12. If the zoom operation signal is input, it is considered that the zoom is on, and an affirmative decision is made in step S21, and the operation proceeds to step S22. When the zoom operation signal is not input, the negative determination is made in step S21 and the process proceeds to step S100.

In step S22, the focus control circuit 8
Sets the zoom flag to 1, resets the AF stop counter to 0, sets the zoom counter to +1 and proceeds to step S23. Here, the AF stop counter is
This is a counter (not shown) in the focus control circuit 8 that counts the time during which the operation processing (focus detection processing) is prohibited. The zoom counter is a counter (not shown) in the focus control circuit 8 that measures the time during which the zoom operation switch 12 is operated. Both AF stop counter and zoom counter
Counting is performed when the count flag = 1, and is not counted when the count flag = 0.

In step S23, the focus control circuit 8
Outputs a zoom lens drive command to the zoom motor driver 5 in response to an operation signal from the zoom operation switch 12 to perform zoom control processing. After the zoom control, the process shown in FIG. 4 ends.

FIG. 5 is a flow chart for explaining the processing flow of the AF delay section in step S100. Figure 5
In step S101, the focus control circuit 8 determines whether the count value of the zoom counter exceeds the zoom counter threshold value. The count value is obtained by counting the count signal from the timer circuit 13 input to the focus control circuit 8. The focus control circuit 8 has a zoom counter>
If the threshold for the zoom counter is satisfied, step S10
If 1 is affirmatively determined, the process proceeds to step S103. If zoom counter> zoom counter threshold is not satisfied, then step S101 is negatively determined and the process proceeds to step S102. An affirmative decision in step S101 is made when the zoom operation time is longer than the predetermined time, and a negative decision in step S101 is made when the zoom operation time is shorter than the predetermined time.

In step S102, the focusing control circuit 8 sets the AF stop counter threshold value to the first threshold value, and then proceeds to step S104. In step S103,
The focus control circuit 8 sets the AF stop counter threshold to a second threshold smaller than the first threshold, and proceeds to step S104.

In step S104, the focus control circuit 8 determines whether or not the zoom flag is 0. The focus control circuit 8 makes an affirmative decision in step S104 if the zoom flag = 0 to proceed to step S105. In this case,
It is assumed that the zoom operation switch 12 is not operated and that the zoom operation has not been completed. In step S105, the focus control circuit 8 performs the above-described hill-climbing type focus detection processing, and outputs a focus lens drive command to the focus motor driver 7. Then, the processing according to FIG. 5 and the processing according to FIG. 4 are terminated. .

On the other hand, the focus control circuit 8 sets the zoom flag =
In the case of 1, a negative decision is made in step S104 and step S
Proceed to 106. In this case, the zoom operation switch 12
Immediately after the end of zoom operation when is not operated. In step S106, the focus control circuit 8 determines whether the count flag is 1. The focus control circuit 8
When the counter flag = 1, an affirmative decision is made in step S106 and the operation proceeds to step S107, and when the counter flag = 0, a negative decision is made in step S106 and the processing in FIG. 5 and the processing in FIG. 4 are ended.

In step S107, the focusing control circuit 8 determines whether or not the count value of the AF stop counter (not shown) exceeds the AF stop counter threshold value. The count value is obtained by counting the count signal from the timer circuit 13 input to the focus control circuit 8. The focus control circuit 8 makes an affirmative decision in step S107 if AF stop counter> AF stop counter threshold value holds to proceed to step S109, and proceeds to step S107 if AF stop counter> AF stop counter threshold value does not hold. A negative decision is made and the operation proceeds to step S108.

In step S108, the focus control circuit 8 sets A
The F stop counter is incremented by 1, and the process shown in FIG. 5 and the process shown in FIG. 4 are terminated. In step S109, the focusing control circuit 8 resets the AF stop counter to 0, resets the zoom flag to 0, and the zoom counter to 0, and then ends the processing in FIG. 3 and the processing in FIG.

According to the second embodiment described above,
In addition to the same operational effects as the above-described first embodiment, the following operational effects are obtained. That is, the operation time of the zoom operation switch 12 is counted by the zoom counter,
When the zoom operation time exceeds the predetermined time corresponding to the threshold value for the zoom counter, the threshold value for the AF stop counter is set to the first value so that the time for prohibiting the drive of the focus motor 6 is shortened.
The second threshold is smaller than the threshold of. On the other hand, if the zoom operation time is less than the predetermined time corresponding to the threshold for the zoom counter, the AF stop counter threshold is set to a first value larger than the second threshold so that the time for prohibiting the drive of the focus motor 6 is lengthened. Use a threshold. When the zoom operation time is short, such as when the zoom operation is performed intermittently, there is a high possibility that the zoom operation will be performed again. Therefore, if the time for stopping the focus motor 6 is lengthened, the stop of the focus motor 6 is continued until the zoom operation is performed again, and as a result, the operability of the camera is improved.

-Third Embodiment-In the third embodiment, the time during which the hill-climbing focus detection processing is prohibited is changed according to the time during which the zoom operation switch 12 is operated, and immediately after the zoom operation is completed. When the zoom operation is performed again, the drive of the focus motor 6 is prohibited after the zoom operation is completed. FIG. 6 is a flowchart illustrating the flow of processing of the AF delay unit in step S100 according to the third embodiment of the present invention, which is performed instead of the processing in FIG.

In step S201 of FIG. 6, the focus control circuit 8 determines whether or not a zoom operation signal is input from the zoom operation switch 12. If the zoom operation signal is input, it is considered that the zoom is on, and an affirmative decision is made in step S201, and the operation proceeds to step S202. If no zoom operation signal has been input, step S20.
A negative determination of 1 is made and the process proceeds to step S204.

In step S202, the focus control circuit 8 sets the AF stop flag to 1 and proceeds to step S203. The AF stop flag is a flag that prohibits AF operation processing (focus detection processing). When the AF stop flag = 1, the focus detection process is prohibited, and when the AF stop flag = 0, the focus detection process is not prohibited. In step S203, the focus control circuit 8 outputs a zoom lens drive command to the zoom motor driver 5 in accordance with the operation signal from the zoom operation switch 12 to perform zoom control processing. Figure 6 after zoom control
And the process of FIG. 4 are terminated.

On the other hand, in step S204, the focus control circuit 8 resets the AF stop counter to 0 and proceeds to step S300. FIG. 7 is a flowchart illustrating the flow of the delay addition process of step S300.
In step S301 of FIG. 7, the focus control circuit 8
It is determined whether the AF stop flag is 1 or not. Focus control circuit 8
When the AF stop flag = 1, an affirmative decision is made in step S301, the operation proceeds to step S302, and the AF stop flag =
If it is 0, a negative decision is made in step S301 and step S301
Proceed to 305.

In step S302, the focus control circuit 8 determines whether or not the count value of the AF stop counter (not shown) exceeds the AF stop counter threshold value. The count value is obtained by counting the count signal from the timer circuit 13 input to the focus control circuit 8. The focus control circuit 8 makes an affirmative decision in step S302 if AF stop counter> AF stop counter threshold is satisfied to proceed to step S304. A negative decision is made and the operation proceeds to step S303.

In S303, the focus control circuit 8 sets A
The F stop counter is incremented by 1, and the processing according to FIG. 7, the processing according to FIG. 6, and the processing according to FIG. 4 are terminated. S304
In, the focus control circuit 8 sets the AF stop flag to 0, resets the AF stop counter to 0, and proceeds to step S305. In step S305, the focus control circuit 8 performs the above-described hill-climbing focus detection processing, and outputs a focus lens drive command to the focus motor driver 7. Then, the processing according to FIG. 7 and the processing according to FIG. Ends the process.

According to the third embodiment described above,
In addition to the same effects as the second embodiment described above, the following effects can be obtained. That is, when the zoom operation is performed again immediately after the zoom operation is finished (negative determination in step S21) (the positive determination in step S201), the drive of the focus motor 6 is prohibited after the zoom operation is finished (negative determination in step S201). can do. When the zoom operation is continuously performed at short intervals, such as when performing a delicate zoom operation intermittently, it is highly likely that the zoom operation is performed again. Therefore, if the time for stopping the focus motor 6 is lengthened, the stop of the focus motor 6 is continued until the zoom operation is performed again, so that the operability of the camera is improved.

The correspondence between each constituent element in the claims and each constituent element in the embodiment of the invention will be described. The lens unit 1 is a photographing zoom lens, and the focus evaluation value calculator 9 is an evaluation value calculation circuit. , Focusing control circuit 8
The focus motor driver 7 corresponds to the drive signal output circuit, and the focus control circuit 8 corresponds to the operation signal detection circuit and the control circuit.

[0045]

As described in detail above, the present invention has the following effects. (1) In the focus detection device according to the invention described in claims 1 to 3, when the zoom operation signal for changing the angle of view of the photographing zoom lens is detected, the driving of the lens for focus detection is stopped. As a result, the focus evaluation value changes according to the change in the angle of view, and the lens is not driven in a state where it is difficult to detect the focus adjustment state, so that unnecessary lens drive can be prevented. (2) In the invention described in claim 2, the time for stopping the lens drive is changed according to the time during which the zoom operation signal is continuously detected. For example, when the zoom operation is intermittently performed, such as when the zoom operation time is short, the drive stop time can be lengthened and the lens drive can be stopped until the next zoom operation, improving the operability of the camera. To do. (3) In the invention according to claim 3, in addition to (2) above,
When the operation signal is detected again immediately after the zoom operation signal is no longer detected, the time for stopping the lens drive is changed. For example, when the zoom operation is continuously performed at short intervals, such as when performing a delicate zoom operation intermittently, the drive stop time can be changed and the lens drive can be continuously stopped until the next zoom operation.

[Brief description of drawings]

FIG. 1 is a block diagram showing an outline of a focus detection device for an autofocus camera according to a first embodiment.

FIG. 2 is a diagram showing an example of a relationship between a position of a focus lens and a focus evaluation value.

FIG. 3 is a flowchart showing a flow of focus detection processing performed by a focus control circuit of the autofocus camera.

FIG. 4 is a flowchart showing a flow of focus detection processing performed by a focus control circuit of the autofocus camera according to the second embodiment.

FIG. 5 is a flowchart illustrating a processing flow of an AF delay unit.

FIG. 6 is a flowchart illustrating a processing flow of an AF delay unit according to a third embodiment.

FIG. 7 is a flowchart illustrating a flow of delay addition processing.

[Explanation of symbols]

1 ... Lens unit, 2 ... Zoom lens, 3 ... Focus lens, 4 ... Zoom motor, 5 ... Zoom motor driver, 6 ... Focus motor, 7 ... Focus motor driver,
8 ... Focus control circuit, 9 ... Focus evaluation value calculator,
10 ... Image sensor, 11 ... Release switch,
12 ... Zoom operation switch, 13 ... Timer circuit

Claims (3)

[Claims] 1. An image pickup device for picking up a subject image through a photographing zoom lens, an evaluation value calculation circuit for calculating a focus evaluation value using an image pickup signal output from the image pickup device, and an operation for the evaluation value calculation circuit. Drive signal output circuit for outputting a drive signal for driving the photographing zoom lens so as to maximize the focus evaluation value, and operation signal detection for detecting a zoom operation signal for changing the angle of view of the photographing zoom lens A circuit and an operation signal is detected by the operation signal detection circuit,
A focus detection device, comprising: a control circuit that controls the drive signal output circuit so as to prohibit the output of the drive signal for a predetermined time. 2. The focus detection device according to claim 1, wherein the control circuit sets a time period during which the output of the drive signal is prohibited in accordance with a time period during which the operation signal detection circuit continuously detects the operation signal. A focus detection device characterized by changing. 3. The focus detection device according to claim 2, wherein the control circuit outputs the drive signal when the operation signal is detected again immediately after the operation signal is no longer detected by the operation signal detection circuit. A focus detection device characterized by changing the time for prohibiting.