JPH04125512A - Lens controller - Google Patents

Abstract

PURPOSE:To greatly improve the responsiveness of an AF operation at the end of wide-angle macrophotography AF by properly controlling a focusing lens at the time of the initialization of the wide-angle macrophotography AF or the postprocessing of the wide-angle macrophotography AF. CONSTITUTION:When a focusing state is entered at the start of the wide-angle macrophotography AF, a focus motor 10 is stopped to stop a front focusing lens 1A. When the focusing state is not obtained at the start of the wide-angle macrophotography AF operation, the focusing lens 1A is driven in its current moving direction for a specific time or by a specific distance and then the focusing lens 1A is stopped. When it is judged that the front lens focusing lens is in a telephoto macrophotography area, the front lens focusing lens is driven to the nearest end of a normal area in the infinite-distance direction at the highest speed. Thus, the focus motor is properly controlled according to the focusing state at the start of the wide-angle macrophotography AF operation to eliminate noises and save the electric power, thereby improving the initial responsiveness of the normal AF operation after the wide-angle macrophotography AF operation.

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 have been developed to improve their functions and operability! Cameras have come to be equipped with a number of functions as standard, such as automatic white balance adjustment (AE), automatic white balance adjustment, zoom function, and macro photography.

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 carrier, etc., and control the focusing lens position so that the sharpness is maximized. A method in which focus is adjusted by using a lens 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 by the blur width (width of the edge part of the subject image) of the video signal extracted by a differentiation circuit, etc. ) using 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 and the width of the blur becomes blurry and wide (the width of the blur becomes blurry and wide), and as the subject becomes in focus, the level of high-frequency components becomes thicker (the blur becomes wider). The width becomes smaller and takes the maximum and minimum values respectively when the focus is completely in focus.Therefore, when the focusing lens is controlled, if the sharpness is low, it is driven as fast as possible in the direction of increasing the sharpness. As the sharpness increases, the speed decreases and the control stops 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, operability has been improved by adopting AF, and more
In order to expand the shooting range and functions by making it possible to deal with the shooting conditions of In this case, focus adjustment is performed by operating the zoom lens, and since the focus control method is different from that in the normal range, focus adjustment in the wide macro range is usually done manually. This was a cause of impeding improvements in operability.

(Problem to be Solved by the Invention) However, in order to automate focus adjustment in the wide macro area, it is conceivable to perform mountain climbing AF sub-control of the zoom lens based on focus detection information in the wide macro area. Since the focus adjustment control system is different between the macro area and the normal area, there is a problem that the responsiveness of the AF operation deteriorates when returning to the normal AF operation after completing the wide macro photography area in the wide macro area.

Further, the motor for driving the focusing lens operates during the wide macro AF operation, which causes serious problems such as increases in drive noise, power consumption, and other drive noises, even though they are not related to focus adjustment.

(Means for Solving the Problems) The present invention has been made to solve the above-mentioned problems, and is characterized by: a first focusing means that performs focusing operations in mutually different areas; a second focus adjustment means; a switching means for switching between the first focus adjustment means and the second focus adjustment means according to the area to be focused; When switching to the second focus adjustment means, the stop position of the first focus adjustment means is controlled based on the focusing state of the first focus adjustment means before switching, and the second focus adjustment means is controlled. and control means for setting the stop position to an initial operating position of the first focus adjustment means when processing is transferred from the first focus adjustment means to the first focus adjustment means.

Further, other features of the present invention include a focus adjusting means capable of performing a focusing operation in a first region and a second region that are different from each other; and an operating area switching means for switching the operating area of the focus adjusting means from the first area to the second area by the operating area switching means, the first area immediately before switching of the focus adjusting means. a self-memory means for storing the operating state in the region; and when switching to the first region after performing a focusing operation in the second region, the focal point is stored based on information stored in the storage means. and control means for controlling the adjustment means.

(Function) This improves the responsiveness of the focusing operation when switching the focusing operation between the wide macro area and the normal area in cameras that can focus in the normal area and wide macro area, especially in the wide macro area. In addition to improving responsiveness when shifting AF operation from to normal range,
Driving noise, power consumption, and driving noise during AF operation within a wide macro area can be reduced.

(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, reference numeral 1 indicates a reflective lens system, which includes a focusing lens group I with a front lens for adjusting the focus.
A, a zoom lens 111B that performs focus adjustment in a wide macro area along with zoom operation, and a correction system lens group 1c (hereinafter referred to as a force single lens, a zoom lens, and a correction lens, respectively).

In addition, the focusing lens IA has a so-called telemacro area (0.6 m to 1.2 m) that extends its driving range to the close side.
), and is configured so that AF operation 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. 3 is an image sensor, such as a CCD, which photoelectrically converts the subject image formed on the imaging surface by the focusing lens 1 into a captured image, and 4 is an image sensor that converts the damaged image signal output from the image sensor 3 to a predetermined level. A preamplifier that amplifies the
5 is a process in which the video signal output from the preamplifier 4 is subjected to predetermined processing such as gamma correction, blanking processing, and addition of a synchronization signal, converted into a standardized standard television signal, and outputted from the video output terminal. It is a circuit. The television signal output from the process circuit 5 is supplied to a video recorder (not shown), an electronic viewfinder, or the like.

Further, numeral 6 inputs the video signal output from the preamplifier 4, and controls the ig meter 8 via the iris drive circuit 7 in order to control the opening 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 the same (a band pass filter (BPF) that extracts high frequency components necessary for focus detection from the video signal output from the preamplifier 4, and 14 is a band pass filter (BPF) that extracts the high frequency component necessary for focus detection from the video signal output from the video signal. The width of the edge portion) is used to detect focus by utilizing the property that the blur width of the subject becomes smaller as it approaches the in-focus state (the width of the edge portion).Focus detection method using this blur width detection circuit Since the device itself is publicly known, for example, from Japanese Patent Laid-Open No. 103616/1983, a detailed explanation thereof will be omitted.

Reference numeral 15 denotes a gate circuit that applies a gate to the outputs 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 through, and a gate pulse supplied by a logic control circuit 21, which will 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.
The peak value and its peak position coordinates within one field period of the high frequency component based on the output of 3, the blur width information based on the output of the blur width detection circuit 14, and the detection information from each encoder are taken in and processed into a predetermined algorithm. Therefore, 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 the convergence point.

That is, based on the output of the band-pass filter 13 (based on the peak value within one field period of the high frequency component and its peak position coordinates, the movement of the subject is detected for each field, and the changed peak position, i.e. In order to set a focus detection area at a position centered on the subject position, a gate pulse is supplied to the gate circuit 15 to control opening and closing of the gate circuit 15, and only a portion of the video signal corresponding to the focus detection area of the video signal is passed through. let

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 fed together from the band pass 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 a 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 for the rotation direction, rotation speed, rotation/stop, etc. of the focus motor 10 are supplied to the focus drive circuit 9. , to control this. In the wide macro AF mode in the wide macro area, the focus adjustment operation is similarly 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.

In the present invention, the blur width signal output from the blur width detection circuit 14 and the high 1'! output from the bandpass filter 13 are used for focus detection in the present invention. The reason for using the peak value of one wave component is as follows.

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 an output according to the degree of focus even if they are far out of focus, but they are greatly affected by contrast, and blur width information Focusing accuracy cannot be obtained.

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

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, a lens operation input is performed to determine whether the AF mode for wide macro area photography (hereinafter referred to as wide macro photography mode) is set. The section 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 output in step S1 and shooting in the normal area is being performed, the process moves to step S2 and AF in the normal area is performed by driving the front focusing lens. The operation (hereinafter referred to as normal AF mode) is loud.

The operation itself to switch to wide macro shooting mode is to automatically move the zoom lens to the wide macro area by operating an operation unit (not shown), and then set the wide macro AF mode to the wide macro shooting mode.
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. This initial setting is a main part of the present invention, and details will be described later.

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

Then, in step S5, the lens operation input section 17 determines whether or not to continue the wide macro AF operation by detecting whether or not an operation command to cancel the wide macro operation has been output. When a signal to interrupt the operation is detected, step S6
Shifts to the wide macro area AF post-processing routine,
Otherwise, the process moves to the wide macro AF control routine in step S4 and continues the wide macro AF operation.

In the wide macro AF post-processing routine in step S6,
The zoom lens is forced to escape from the wide macro area to the normal area, and the control returns to the wide macro AF start signal detection routine in step S1 to prepare for the next wide macro AF operation.

Next, in the flowchart in FIG. 2 mentioned above,
The cross section operation of the wide macro AF initial setting routine, which is the gist of the present invention, will be explained in detail using the flowchart shown in FIG.

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, and if it is determined that it is located in the so-called telemacro focusing area of 0.6 m to 1.2 m, the process advances to the front lens focusing lens movement routine of step S36. If it is determined that the lens is not within the telemacro region of 0.6 mA-1.2 m but within the normal range of 1.2 m to infinity, the process moves to the focus detection routine of step S32.

In step S31, the front lens focusing lens is within the telemacro area (if the process proceeds to step S32, at the start of the wide macro AF operation, it is detected whether or not it is in focus in the normal AF operation, and If it is in focus, 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, if the focus state is not in the normal AF operation at the time when the wide macro AF operation is started, the process proceeds to step S33 and the focusing lens is moved in the direction in which it is currently moving 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 S36, 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 of 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,
As mentioned above, the reason for the different processing 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 situation in which when the front lens focusing lens is in the telemacro area, a distant object will not be in focus at all when performing a focus adjustment operation in the wide macro area.

In other words, in an AF system in which AF in the so-called telemacro area and wide macro AF coexist, where the subject distance that can be focused with the front lens focusing lens is from 0.6 m to infinity (3), due to optical limitations,
(2) Depending on the conditions at the time of shadowing, 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 aware of the position of the front focusing lens, even when using wide macro AF.
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.

In addition, during wide macro AF operation, the position of the front focusing lens is unrelated to focus adjustment, so by stopping the front focusing lens, noise and power consumption due to short AF driving during wide macro shooting 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 above-described embodiment, at the start of wide macro AF, depending on the in-focus state, the focusing lens may be stopped or
Alternatively, it is moved by a predetermined amount in a predetermined direction and then stopped, but it is not limited to such a sequence.
This control may be performed during wide macro AF operation.

Further, in the above embodiment, if it is determined that the focus 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. However, the invention is not limited to this. At the start of AF, if focusing is in progress, the driving direction of the focus motor is memorized,
After the wide macro AF is completed, the focusing motor may be restarted in the stored direction at a predetermined speed.

When such a sequence is used, when it is determined that the subject is in focus, after the wide macro photographing operation is completed, the focusing motor is not driven and normal focusing is performed without driving the focusing motor.

FIG. 4 is a flowchart showing a switching control process between normal area AF operation and wide macro AF operation in this embodiment.

Specifically, the processing of the wide macro AF initial setting routine shown in step S3 and the wide macro post-processing routine shown in step S4 in the flowchart of FIG. 2 are changed, and are the same as the flowcharts of FIGS. 2 and 3. The same reference numerals will be used for the steps that perform the processing, and the description thereof will be omitted.

In the flowchart of the same figure, if the start of wide macro AF operation is declared in step S1 and an operation to start wide macro AF operation has been performed, the process advances to step S3° and wide macro AF initial settings are performed. It is done.

When entering the wide macro AP initial setting routine, first, in step S31, the area where the front focusing lens is located is determined, and then in step S32, the focusing state immediately before entering the wide macro AF operation is determined.

Here, when starting wide macro AP, the front focusing lens is in the tele macro area (and the prenatal focusing state is determined to enter wide macro AF operation in step S32,
If it is in focus, the focusing lens is stopped at the same position in step S34, and if it is not in focus, the process proceeds to step S38, where the focusing direction, that is, the direction in which the focusing lens is being driven, is memorized. The focusing lens is stopped in step S34.

Thereafter, wide macro AF operation is performed in step S4,
When the end of the wide macro AF operation is detected in step S5, the process moves to a wide macro AF post-processing routine in step S6°.

In the wide macro AF post-processing routine, step S61
It is determined whether or not it was in focus when wide macro AF was started, and if it was in focus when wide macro AF was started and the focusing lens driving direction was not stored in step S38, the focusing lens was not moved. , in focus at the start of wide macro AP (if the focusing lens drive direction is stored in step S38, the process advances to step S62, and step S
When the focusing lens is moved a predetermined amount in the direction stored in step 38, it stops and is set as the initial position for the next AF operation.

After this, the process returns to step S1 and the wide macro A
If the P operation command has not been issued, the process proceeds to step S2, where the normal AF operation is started with the position set in step S61 or step S62 set as the initial position of the focusing lens.

Note that the driving amount of the focusing lens in step S62 described above may be determined by predicting a position that is considered to be close to the focal point from the focusing lens movement speed immediately before starting wide macro AF, or may be determined based on the normal shooting frequency. The focusing lens may be driven and stopped at a position with a high probability of being in focus, taking into consideration the subject condition with a high degree of focus.

In this way, the same effects as those of the first embodiment described above can be obtained.

(Effects of the Invention) As described above, according to the lens control device of the present invention, by appropriately controlling the focusing lens during wide macro AF initial setting or during wide macro AF post-processing, wide macro AF A at the end
The substantial effects are significant, such as being able to significantly improve the responsiveness of F operation, and reducing noise and power consumption due to unnecessary driving of the focusing lens during wide macro AF operation.

[BRIEF DESCRIPTION OF THE 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, and Fig. 2 is a flowchart for explaining the control operation by the lens control device according to the present invention. , FIG. 3 is a flowchart for explaining the initial setting operation at the start of wide macro AF in the flowchart of FIG. 2, and FIG. 4 is a flowchart showing another embodiment of the control operation of the lens control device in the present invention. be. Figure 2

Claims (5)

[Claims] (1) A first lens that performs focusing operations in mutually different areas.
a focus adjustment means and a second focus adjustment means; a switching means for switching between the first focus adjustment means and the second focus adjustment means according to the area to be focused; When switching from the first focus adjustment means to the second focus adjustment means, the first focus adjustment means before the switching
The stop position of the first focus adjustment means is controlled based on the in-focus state of the focus adjustment means, and the stop position is controlled when the process is transferred from the second focus adjustment means to the first focus adjustment means. A lens control device comprising: control means for setting a position to an initial operating position of the first focus adjustment means. (2) In claim (1), the first focus adjustment means is configured to perform focus adjustment in a normal region, and the second focus adjustment means is configured to perform focus adjustment in a wide macro region. A lens control device characterized by: (3) In claim (1), when the control means switches from the first focus adjustment means to the second focus adjustment means, the first focus adjustment means is in an in-focus state. If the focus adjustment means is in focus, the first focus adjustment means is stopped at that position, and when the focus adjustment means is not in focus, the first focus adjustment means is controlled so as to be stopped at a position where the first focus adjustment means has been driven by a predetermined amount in the driving direction. A lens control device comprising: (4) A focus adjusting means capable of performing a focusing operation in a first region and a second region that are different from each other, and an operating region switching device that switches the operating region of the focusing means between the first region and the second region. and an operation in the first area immediately before switching of the focus adjustment means when the operation area of the focus adjustment means is switched from the first area to the second area by the operation area switching means. storage means for storing a state; and control for controlling the focus adjustment means based on information stored in the storage means when switching to the first region after performing a focusing operation in the second region; A lens control device comprising: means. (5) In claim (4), the storage means stores the movement direction of the focus adjustment means immediately before the switching operation, and the control means performs a focusing operation within the second region. When the operating region of the focus adjustment means is switched to the first region after performing the above, the focus adjustment means moves a position driven by a predetermined amount in the direction stored in the storage means within the first region. A lens control device configured to be set at an initial operating position.