JPH04125511A - lens control device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a lens control device suitable for use in video equipment such as video cameras and electronic still cameras.

(Prior Art) In recent years, the development of video equipment such as video cameras and electronic cameras has been remarkable, and in particular, automatic focus adjustment devices (AF) and automatic aperture control devices (AE) have been developed to improve their functions and operability. , automatic white balance adjustment, zoom function, etc.
Many functions such as macro photography have come to be standard equipment.

By the way, automatic focusing devices detect the sharpness of the screen from the video signal obtained by photoelectrically converting the subject image using an image sensor, etc., and control the focusing lens position so that the sharpness is maximized. A method that allows focus adjustment is becoming mainstream.

The sharpness is generally evaluated by the intensity of high frequency components of the video signal extracted by a band pass filter (BPF), or the blur width (width of the edge part of the subject image) of the video signal extracted by a differentiation circuit, etc. Use detection strength, etc.

This means that when shooting a normal subject image, when the subject is out of focus, the level of high-frequency components is small (the width of the blur becomes blurred and wide), and as the subject becomes in focus, the level of high-frequency components becomes thicker ( The width of the bokeh is small (and reaches its maximum and minimum values, respectively, when it is completely in focus. Therefore, when controlling the focusing lens, if the sharpness is low, it is as high as possible in the direction of It is driven at high speed, decelerates as the sharpness becomes high, and is controlled to stop at the top of the peak of high precision (sharpness).This method is generally called the mountain climbing autofocus method (mountain climbing AF).
It is called.

With the adoption of such an automatic focus adjustment device,
Conventionally, the operability of video cameras and the like, especially those used to shoot moving images, has improved dramatically and has become an essential requirement in recent years.

In addition to improving operation and performance through the adoption of AF, the so-called telemacro AF function expands the focusing range to the close-up area in order to accommodate more shooting conditions and expand the shooting range and functions. A system with the following has been proposed. This extends the operating range of the conventional front focusing lens to the near side, making it possible to focus on closer objects.

A wide macro focus function has also been proposed that controls a zoom lens in the wide macro range, where focusing has traditionally been done manually.

This means that in wide macro shooting areas, focus is adjusted by operating the zoom lens.
Since the focus control method and control in the normal area are different, focus adjustment in the wide macro area is normally performed manually, which has been a cause of impeding improvements in operability.

In addition, so-called power wide macro focusing has been proposed in which wide macro focusing is performed by driving the zoom lens through a switch input operation in cases where the zoom lens cannot be directly operated manually.

(Problems to be solved by the invention) However, from the viewpoint of operability, the telemacro AF
There is an extremely strong demand for automating various operations in systems that have a mix of functions and wide macro photography areas, and it is difficult to perform automatic focusing in the normal area and manual focusing in the macro area, which reduces operability. Therefore, there was a problem in that the characteristics of the AF function in the normal range could not be utilized.

Therefore, in order to automate focus adjustment in the wide macro area, it is conceivable to perform mountain climbing A and F control of the zoom lens based on focus pressure detection information in the wide macro area. Since the adjustment control system is different, the wide macro AF operation in the wide macro area is finished and the A in the normal area is resumed.
There is a problem in that the AF operation tends to become unstable when the F operation is started.

This is because the number of subject positions at the start of Wide Macro AF and the number of subject positions at the end of Wide Macro AF are not necessarily m, and when starting operation area A and F after Wide Macro AF operation, the subject may be lost and the subject may be out of focus. This is because it may take a long time to reach the state.

(Means for Solving the Problems) The present invention has been made to solve the above-mentioned problems, and is characterized by a first method that performs a focus adjustment operation by moving a first area. a lens control means; a second lens control means that performs a magnification change operation in a second region and performs focus adjustment in a third region formed by extending the second region; and the first lens control means switching means for switching between a focus adjustment operation by the second lens control means and a focus adjustment operation by the second lens control means; and a control means for moving the second focus adjustment means to a predetermined position within the second region when the lens control means is switched to a focus adjustment operation in the first region. It is in.

Another feature of the present invention is that the first lens control means performs a focusing operation by moving a first region, and the first lens control means performs a zooming operation in a second region and extends the second region. a second lens control means for performing focus adjustment in a third region, a switching means for switching between a focus adjustment operation by the first lens control means and a focus adjustment operation by the second lens control means; When the switching means switches from the focus adjustment operation in the third region by the second lens control means to the focus adjustment operation in the ml region by the first lens control means, the second focal point The lens control device includes control means for moving the adjusting means to a predetermined position within the second region and operating the first lens control means at a predetermined speed.

(Function) As a result, when transitioning to AF operation in the normal area after AF operation in the wide macro area, the so-called zoom lens that performs wide macro AF is positioned at the wide end with the deepest depth of field, It is possible to control to a state where focusing is easy, and the initial stability of the AF operation in the normal region can be improved.

(Embodiment) Hereinafter, an embodiment of the automatic focusing device according to the present invention will be described in detail with reference to the respective figures.

FIG. 1 is a block diagram showing a case where the lens control device of the present invention is implemented in a video camera.

In the figure, l indicates a photographic lens system, which includes a focusing lens group I with a front lens for focus adjustment.
A. Zoom lens group IB, which performs focus adjustment in the wide macro area along with zoom operation, and correction system lens group 1.
(hereinafter referred to as a focusing lens, a zoom lens, and a correction lens, respectively).

In addition, the focusing lens IA has a so-called telemacro region (0.6 m to 1.2
m), and is configured so that A and F operations can be performed in this telemacro area as well as in the normal area.

Further, the focusing lens IA is driven and controlled via a focus motor drive circuit 9 and a focus motor 1°. Also, the zoom lens IB has a zoom motor drive circuit 1.
1 and a zoom motor 12. Reference numeral 2 denotes an aperture (iris) that controls the amount of incident light, and its drive is controlled via an iris drive circuit 7 and an ig meter 8 for driving the aperture. Reference numeral 3 denotes an image sensor, such as a CCD, which photoelectrically converts the subject image formed on the imaging surface by the focusing lens 1 into an image signal, and 4 amplifies the image signal output from the image sensor 3 to a predetermined level. preamp,
5 is a process circuit that performs predetermined processing such as gamma correction, blanking processing, and addition of a synchronization signal to the video signal output from the preamplifier 4, converts it into a standardized standard television signal, and outputs the signal from the video output terminal. It is. The television signal output from the process circuit 5 is supplied to a video recorder (not shown), an electronic viewfinder, or the like.

Further, 6 inputs the video signal output from the preamplifier 4, and controls the aperture amount of the diaphragm 2 so that the level of the video signal is constant at a predetermined level. This is an iris control circuit that automatically controls.

13 is a band pass filter (BPF) that extracts high frequency components necessary for focus detection from the video signal output from the preamplifier 4; The focus detection circuit uses the property that the blur width of the subject decreases as it approaches the in-focus state. The focus detection method itself using this blur width detection circuit is well known, for example, from Japanese Patent Application Laid-Open No. 103616/1983, so a detailed explanation thereof will be omitted.

Reference numeral 15 denotes a gate circuit that applies a gate to the pressure of the band pass filter 13 and the blur width detection circuit 14 and allows only signals corresponding to a designated area on the imaging screen to pass, and a gate pulse supplied by a logic control circuit 21 to be described later. Accordingly, only the signal corresponding to a specified area in the video signal for one field is passed through, thereby extracting a high frequency component at an arbitrary position within the imaging screen. You can set the area. Reference numeral 16 denotes a peak position detection circuit that detects the position in the horizontal and vertical directions within the imaging screen where the peak value of the higher frequency component in the video signal corresponding to the focus detection area extracted by the gate circuit 15 is obtained. This peak position detection circuit is
It is detected in which block the focus detection area is divided into a predetermined number of blocks in the horizontal and vertical directions, and the peak position detected in one field period is located in the horizontal and vertical directions.
It outputs the vertical coordinate.

Further, 17 is a lens operation input unit that reads various control operations regarding the lens, such as zoom operation, AF mode switching, wide macro AP ON/OFF, and high-speed shutter setting.

Further, 18 is a focus encoder that detects the moving position of the focusing lens IA, 19 is a zoom encoder that detects focal length information varied by the zoom lens IB, and 20 is an iris encoder that detects the aperture amount of the diaphragm 2. This detection information is supplied to the logic control circuit 21.

Reference numeral 21 denotes a logic control circuit that centrally controls the entire system, and is configured by a microcomputer, for example, and includes an input/output port (not shown), an A/D converter, a read-only memory (ROM), and a random access memory (RAM). ). This logic control circuit operates on the bandpass filter 1 outputted from the peak position detection circuit 16.
Based on the output of the blur width detection circuit 14, the peak value and its peak position coordinates within one field period of the high frequency component based on the output of No. Calculations are performed according to an algorithm, and based on these time-series changes, the position, size, movement direction, and movement response speed of the focus detection area on the imaging screen are set, that is, the subject is tracked.
It calculates the moving direction and moving speed of the focusing lens to obtain a focused point.

That is, based on the peak value within one field period of the high frequency component based on the output of the bandpass filter 13 and its peak position coordinates, the movement of the subject is detected for each field, and the changed peak position, that is, the subject The focus detection area should be set around the position (
A gate pulse is supplied to the gate circuit 15 to control opening and closing, and only a portion of the video signal corresponding to the focus detection area of the video signal is allowed to pass through.

Furthermore, the logic control circuit 21 performs focus detection on the subject and performs focus adjustment based on the video signal corresponding to the focus detection area set as described above. That is, the blur width information supplied from the blur width detection circuit 14 and the peak value information of the high frequency component supplied from the bandpass filter 13 are taken in, and based on these time-series changes, the minimum blur width value in one field period is determined. In order to drive the front focusing lens IA to the position where the peak value of the high frequency component is the minimum and the peak value of the high frequency component is the maximum, control signals such as the rotation direction, rotation speed, and rotation/stop of the focusing motor 10 are sent to the focus drive circuit 9. supply and control this. In addition, in wide macro AF mode in the wide macro area,
Similarly, the focus adjustment operation is performed by driving the zoom lens IB based on the blur width corresponding to the degree of focus and the peak value information of the high frequency component.

At this time, the logic control circuit 21 adjusts the size of the focus detection area according to the degree of focus and the depth of field calculated from the aperture value and focal length detected by the aperture encoder 20 and zoom encoder 19. control the speed, movement range, and movement response speed.

In this way, it is possible to keep the camera in focus while tracking a moving subject image.

The reason why the blur width signal output from the blur width detection circuit 14 and the peak value of the high frequency component output from the band pass filter 13 are used for focus detection in the present invention is based on the following rationale.

In other words, the bokeh width becomes smaller as it approaches the in-focus point, and reaches its minimum value at the in-focus point, and is less affected by the contrast of the subject, making it possible to obtain high focus detection accuracy. However, on the other hand, the dynamic range is narrow ( If the focal point is set too wide (out of focus, sufficient detection accuracy cannot be obtained).

On the other hand, high-frequency components have a wide dynamic range and can obtain output according to the degree of focus even if they are far out of focus. cannot obtain any focusing accuracy.

Therefore, by combining these, it is possible to realize a focus detection method with a wide dynamic range and high detection accuracy near the in-focus point.

Next, automatic focusing operation in a wide macro area, which is the gist of the lens control device of the present invention, will be explained step by step with reference to the flowchart shown in FIG.

In FIG. 2, when the lens control operation by the logic control circuit 21 is started, in step S1, it is first determined whether the AF mode for wide macro area manipulation (hereinafter referred to as wide macro shooting mode) is set or not. The operation input unit 17 detects the presence or absence of the wide macro AF start signal. Step s1 is a routine for detecting a wide macro AF start signal among various lens operation inputs. If the wide macro AF start signal is not focused in step s1 and photography is being performed in the normal area, the process moves to step S2, where shooting is performed in the normal area by driving the front focusing lens. A, F operation (hereinafter referred to as *AF mode).

The operation to set the wide macro photography mode itself is to automatically move the zoom lens to the wide macro area by operating an unspecified operation section, and to set the wide macro photography mode.

In step S1, if the wide macro AF mode is set and the wide macro AF start signal is output, the process advances to step s3 to shift to the wide macro AF mode, and focus control is performed by operating the zoom lens. mode, and initial settings in the wide macro AF operation mode are performed. Details of this initial setting will be described later.

After completing the initial settings in step S3, the process proceeds to step S4, where a wide macro AF control operation is performed, and actual focusing operation becomes possible by driving the zoom lens without using the focusing lens.

Then, in step S5, the lens operation reading circuit 17 determines whether or not to continue the wide macro start signal by detecting whether or not an operation command to cancel the wide macro operation has been output.
When a signal that interrupts the operation is detected, step S
In other cases, the process moves to the wide macro area AF post-processing routine in step S4, and the wide macro AF operation continues.

In the wide macro area AF post-processing routine of step S6, the zoom lens is forcibly removed from the wide macro area to the normal area, and the control returns to the wide macro area AF start signal detection routine of step S1. This is to prepare for the occurrence of wide macro AF operation. This wide macro post-processing routine constitutes the main part of the present invention, and will be described in detail later.

Next, the control operation of the wide macro area AF initial setting routine in the flowchart shown in FIG. 2 described above will be explained in detail using the flowchart shown in FIG. 3.

In step S1 in FIG. 2, it is detected that the wide macro AF mode has been set by the wide macro start signal, and when the wide macro AF initial setting routine processing in step S3 is started, immediately step S31 in FIG.
The position of the front lens focusing lens is detected by the focus encoder 18 at
If it is determined that the lens is located in the telemacro area (hereinafter referred to as the telemacro area), proceed to the front lens focusing lens movement routine in step S36, and proceed to the front lens focusing lens movement routine in step S36. If it is determined that the focus is within the regression region, the process moves to the focus detection routine of step S32.

If the front lens focusing lens is not within the telemacro area in step S31 and the process proceeds to step S32, when wide macro AF operation is started, it is detected whether or not it is in focus in normal AF operation, and the focus is If it is, the process advances to step S34, where the focus motor is stopped and the front lens focusing lens IA is stopped.

Further, in step S32, when the wide macro AF operation is started and the focus is not in the normal AF operation, the process proceeds to step s33 and the focusing lens is moved in the current direction for a predetermined time or a predetermined distance. After driving, the focusing lens is stopped in step S34.

On the other hand, if it is determined in step S31 that the front focusing lens is within the telemacro area,
Proceeding to step 336, the front focusing lens is driven toward infinity at the highest speed until it reaches a position 1.2 m from the closest end of the normal range. Then, in step S37, the position of the focusing lens is detected, and if it is detected that the 1.2 m focusing position has been reached, the process proceeds to step S34, where the focusing motor is stopped and the focusing lens is stopped.

After the focusing lens stops in step S34 and the initial setting operation of the focusing lens associated with the start of the wide macro AF operation described above is completed, step S35
Then, the zoom lens is set to the initial position within the wide macro area, the wide macro AF initial setting operation is completed, and control is returned to step s4 in the flowchart of FIG.

Here, when starting wide macro AF operation, depending on whether or not the front focusing lens is in the telemacro area,
The reason why the processing is different as described above will be explained.

First, when starting wide macro AF, if the front focusing lens is in the telemacro area, the subject itself is not in focus in the wide normal area, so it will be driven at maximum speed to a position 1.2 m from the closest end of the normal area. . This is to prevent a distant subject from being out of focus when the front lens focusing lens is in the telemacro range and a focus adjustment operation is performed in the wide macro range.

In other words, in an AF system that mixes AF in the so-called tele-macro area, where the subject distance that can be focused with the front lens focusing lens is from 0.6 m to infinity, and wide macro AF, due to optical limitations, the shooting Depending on the conditions at the time, even if the image is supposed to be in focus, it may not be in focus at all. For this reason, when performing wide macro AF, for example, if the front focusing lens is in the telemacro area, a phenomenon occurs in which a distant object is not brought into focus at all.

Therefore, in the present invention, before starting wide macro AF, the front focusing lens is controlled to be forcibly retracted to the normal area. As a result, the photographer does not have to be conscious of the position of the front focusing lens (even when shooting in a wide macro area,
This means that even when photographing a distant subject, it is possible to obtain an image that does not look unsightly.

On the other hand, if the front focusing lens is not in the telemacro area at the start of wide macro AF, control differs depending on the AF state. In other words, if the subject is in focus, there is a high possibility that the subject will be in the vicinity even when wide macro AF ends. If this is not the case, there is a high possibility that the subject is in the direction in which the front focusing lens is being driven at the time of starting wide macro AF.

Therefore, in step S32, the state of the subject is determined by detecting the in-focus state, and if it is in the in-focus state, the focus motor is stopped on the spot, and if not,
In other words, if the focus is in the middle of a focusing operation, the focus motor is stopped by driving the focus motor by a predetermined amount in the direction in which it is currently moving.
When starting normal AF operation after wide macro AF ends, the probability of losing sight of the subject is reduced and initial responsiveness is improved.

Also, during wide macro AF operation, the position of the front focusing lens has no relation to focus adjustment, so by stopping the front focusing lens, noise and power consumption caused by AF driving during wide macro photography can be reduced.
Driving noise etc. can be reduced.

As described above, according to the present invention, by appropriately controlling the focus motor according to the focusing state at the start of wide macro shooting operation, noise and power consumption caused by driving the focusing lens during wide macro AF operation can be reduced. etc., and improve the initial responsiveness of the normal AF operation after the wide macro AF operation is completed.

According to the present invention, when wide macro AF is started, depending on the in-focus state, the focusing lens is stopped or moved by a predetermined amount in a predetermined direction and then stopped, but the sequence is limited to such a sequence. Instead, this control may be performed during wide macro AF operation.

Furthermore, in this embodiment, if it is determined that the camera is not in focus at the start of wide macro AF, the camera is moved by a predetermined amount in a predetermined direction and then stopped. Sometimes, if a focusing operation is in progress, the driving direction of the focusing motor may be stored, and after wide macro AF is completed, the focusing motor may be restarted at a predetermined speed in the previously stored direction.

When such a sequence is used, when it is determined that focus is achieved, normal focusing control is performed in that state without driving the focusing motor after the wide macro AF operation is completed.

Next, the wide macro post-processing routine which forms the main part of the present invention will be explained.

In the flowchart of FIG. 2, when a wide macro AF end signal is detected that declares the end of the wide macro AF operation in step S5, the wide macro AF operation is started in step S6.
The process moves to a post-processing routine, and an operation is performed to move the zoom lens from the wide macro area to the area where normal magnification is changed.

FIG. 4 is a flowchart showing the processing in the wide macro post-processing routine.

When the wide macro post-processing routine is started, in step S61, the zoom lens is driven at the highest speed in the direction of exiting from the wide macro area to the normal area where the zooming operation is performed.

Then, in step S62, it is determined whether the zoom lens has reached the wide end of the normal range by analyzing the signal obtained from the zoom encoder 19, and if it is detected that the zoom lens has reached the wide end, the process proceeds to step S63. Then, the zoom lens drive motor 12 is stopped.

Then, after stopping the zoom lens at the wide end, step S
The process proceeds to step 64, where the focusing lens is again operated to perform a focusing operation within its normal range, and the process returns to step S1 in FIG. 2, whereupon the aforementioned control operation is repeated in response to a new operation.

Now, the reason why the zoom lens is stopped at the wide end in the normal range in which the zooming operation is performed when the wide macro AF operation is finished will be explained.

Generally, the subject position at the start of wide macro AF does not necessarily match the position at the end.

Therefore, as described above, if the focusing lens position is stopped on the spot at the start of wide macro AF, when normal AF is performed again after completion, the focusing lens position will not be appropriate and there is a high probability that the subject will be lost.

As a result, the initial stability of the AF operation after switching deteriorates, causing problems such as a long time being required to obtain a focused state.

Therefore, by stopping the zoom lens at the wide end of the normal range for zooming after wide macro AF is completed, the depth of field is deepened, making it easier to focus on the subject, and reducing the possibility of losing sight of the subject. ing.

As described above, according to the present invention, wide macro AF
During post-processing, by setting the stop position of the zoom lens to a position that provides the deepest depth of field under the shooting conditions, the initial stability of normal AF after wide macro AF is completed can be significantly improved. can be done.

According to the above embodiment, the zoom lens is stopped at the wide end of the normal range when wide macro AF ends, but
For example, as shown in the flowchart of FIG. 5, the zoom lens is moved at high speed to the normal area in step S61, and after entering the normal area is detected in step S62, In step S65, it may be stopped at a position where the movement has been continued for a predetermined period of time. Note that in the flowchart of FIG. 5, step S65
The rest is the same as the flowchart in FIG. 4, and the explanation will be omitted.

Further, according to the above embodiment, the zoom lens is only controlled when the wide macro AF operation ends, but the method is not limited to this method, and the front lens focusing lens is moved in a predetermined direction toward infinity. At initial speed, restart
It is also possible to start the normal AF operation quickly and smoothly.

That is, as shown in the flowchart of FIG. 6, after the wide macro AF operation is finished and the zoom lens is stopped at the wide end in the normal zoom range, the focusing lens is moved toward infinity at a predetermined initial speed in step S66. Then, in step S64, normal area AF is restarted. This allows a quick and smooth transition from wide macro AF operation to normal area AF operation.

Note that in this embodiment, steps other than step S66 are the same as the flowchart shown in FIG. 4, and detailed explanation will be omitted.

(Effects of the Invention) As described above, according to the lens control device of the present invention, by setting the zoom lens to the optimum position at the end of the wide macro AF operation, an initial state in which it is easy to focus within the normal range can be achieved. After wide macro AP is completed, initial stability can be greatly improved when control is transferred to normal area AF operation, and smooth and quick processing can be performed.
Responsiveness in switching operations is improved, and an AF system with good operability can be realized.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration when the lens control device according to the present invention is applied to a video camera, FIG. 2 is a flowchart for explaining the control operation by the lens control device according to the present invention, and FIG. 4 is a flowchart for explaining the initial setting operation at the start of wide macro AF; FIG. 4 is a flowchart for explaining the post-processing operation at the end of wide macro AF in the flowchart of FIG. 2; FIG. 6 is a flowchart showing another embodiment of the control operation of the lens control device according to the present invention, and FIG. 6 is a flowchart showing another embodiment of the control operation of the lens control device according to the present invention.

Claims (4)

[Claims] (1) A first area that moves the first area to perform a focus adjustment operation.
a second lens control means that performs a magnification change operation in a second region and performs focus adjustment in a third region formed by extending the second region, and the first lens control means. switching means for switching between a focus adjustment operation by the second lens control means and a focus adjustment operation by the second lens control means; control means for moving the second focus adjustment means to a predetermined position within the second region when the first lens control means is switched to a focus adjustment operation in the first region; A lens control device characterized by: (2) The lens control device according to claim (1), wherein the predetermined position is an end of the second area that is closer to the third area. (3) In claim (1), the lens control device is characterized in that the predetermined position is a position moved for a predetermined time to a side opposite to the third area within the second area. . (4) The first area that moves the first area and performs the focus adjustment operation.
a second lens control means that performs a magnification change operation in a second region and performs focus adjustment in a third region formed by extending the second region, and the first lens control means. switching means for switching between a focus adjustment operation by the second lens control means and a focus adjustment operation by the second lens control means; When the first lens control means is switched to focus adjustment operation in the first region, the second focus adjustment means is moved to a predetermined position within the second region, and the first lens control means is moved to a predetermined position within the second region. A lens control device comprising: control means for operating the lens control means at a predetermined speed.