JPH06205259A - Video camera - Google Patents

Abstract

PURPOSE:To ensure the focus control during zooming within an entire fluctuation range of a variable power rate without deterioration in the picture quality. CONSTITUTION:In the initial state of zooming, a microcomputer 10 executes zoom control by the electronic zooming and moves a focus lens 4 to execute in-focus control to switch a focal state from a non in-focus state before the zooming to the in-focus state and selects a cam locus corresponding to the position of a zoom lens and the focus lens in the in-focus state and reads it from an EEPROM 5, and controls the zoom lens 2 to be moved and to move the focus lens 4 in following to the zoom lens 2 according to the cam locus selected in the in-focus state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera having a function of performing focusing control during zooming.

[0002]

2. Description of the Related Art In recent video cameras, so-called inner focus lenses have been widely used for focus adjustment by controlling movement of a rear lens group in a lens system in order to downsize the device.

In this type of inner focus type lens system, when focusing control is performed during zoom operation by movement control of the zoom lens, generally, a focus lens corresponding to a zoom lens position for each of a plurality of predetermined subject distances. The focus position locus is stored in advance as a so-called cam locus, and the focus lens is controlled to move during the zoom operation so as to follow the cam locus.

Further, in recent years, a video camera has been realized which employs an electronic zoom system in which a magnification is changed by electronic processing and an electronic focus system in which focusing control is performed by electronic processing.

In the electronic zoom system of this type of video camera, for example, an optical image input from an optical lens system is photoelectrically converted by a photoelectric conversion element such as a CCD, and the photoelectrically converted image signal is taken into a memory and stored in the memory. In addition to changing the read range of the image signal, the angle of view (magnification) is changed by interpolating the signal in the vertical and horizontal directions with respect to the read image signal.

On the other hand, in the electronic focus system, for example,
By holding each peak value of the signal indicating the sharpness of the rising edge component and the falling edge component in both the vertical and horizontal directions of the photoelectrically converted image signal, and comparing the both peak values, the focus state is achieved. It is determined whether or not it is in the in-focus state (front focus state or rear focus state). If both peak values are not equal and it is determined that they are out of focus state, both peak values are The movement of the focus lens is controlled so that they are equal to each other and are in focus.

[0007]

However, as described above, when the focus control is performed during zooming using the cam locus, the cam locus to be used is the zoom lens position and the focus lens position before zooming. Since the corresponding cam locus is selected, if the pre-zooming state is out of focus, the cam locus corresponding to the original subject distance will not be selected and the image will be out of focus during zooming. It was

Since such a problem does not occur in the video camera adopting the above electronic zoom system, it is conceivable that the focusing control during zooming is all performed electronically, not optically.

However, there is a problem in performing all electronically. That is, in the electronic zoom system, since the angle of view is changed by the interpolation process as described above, there is a fundamental defect that the image quality is inevitably worse than in the optical zoom system.

Further, since the plurality of cam loci corresponding to the respective object distances converge in the wide direction, particularly when zooming from the wide side to the tele side,
It takes time to select the cam locus to follow,
In the worst case, there is a problem that the cam locus is selected by mistake and the image becomes out of focus.

Particularly in recent zoom lenses for video cameras, the zoom ratio has been increased, and particularly on the telephoto side, the zoom ratio tends to change greatly with a slight movement. Therefore, if the relative positional relationship between the focus lens and the zoom lens for maintaining focus is lost during zooming, the focus degree will be greatly reduced even if it is a small amount. It is expected that it will be in a state.

The second problem is as follows. When the video camera is equipped with the high-magnification zoom lens as described above as a standard feature, it is not uncommon to perform panning on a plurality of subjects at different distances, and perform panning simultaneously with zooming. In this case,
It becomes more difficult to maintain the relative positional relationship between the zoom lens and the focus lens, and when repeatedly panning and zooming between specific subjects, it is time consuming to focus the camera each time. This may result in a blurred image being shot for a long time.

The present invention has been made under such circumstances, and a first object thereof is to make sure that focusing control during zooming can be surely performed in the entire variation range of the magnification change without deteriorating the image quality. Is to

A second object of the present invention is to store a focus and a zoom lens position at a preset object distance and magnification, and instantly move each lens to that position to enable fast control without blurring. To do so.

[0015]

In order to achieve the above-mentioned first object, the video camera according to the first invention is configured so that the focus position of the focus lens corresponding to the plurality of positions of the zoom lens can be adjusted for each of the plurality of subject distances. Storage means for storing the trajectory,
A first drive unit that drives the zoom lens, a second drive unit that drives the focus lens, an electronic zoom unit that performs zoom control based on a captured video signal, and an electronic zoom unit that performs the zoom control at an initial stage of zooming. First control means for performing zoom control by electronic zoom means and at the same time for focusing control by driving the focus lens by the second drive means, and initial stage zooming control by the first control means In performing the zooming control by taking over the above, the selection means for selecting the locus in the storage means corresponding to the positions of the zoom lens and the focus lens at the time when the control by the first control means is finished; The zoom lens is moved by controlling the driving means of the focus lens, and the focus lens is moved in accordance with the locus selected by the selecting means. 'S have a second control means for controlling said second drive means so as to move following to the zoom lens.

In order to achieve the second object, the video camera according to the second invention sets the position of the zoom lens at an arbitrary point during shooting and the focus position of the focus lens corresponding to the position of the zoom lens. Storage means for storing, first driving means for driving the zoom lens, second driving means for driving the focus lens, instruction means for instructing lens movement based on the stored contents of the storage means, and In response to the instruction from the instruction means, the first drive means is controlled so as to move the zoom lens to the position stored in the storage means, and the first drive means is stored in the storage means when the zoom lens is moved. And a control unit that controls the second drive unit so as to move the focus lens to a focus position.

In order to achieve the above second object, in the video camera according to the third invention, in addition to the constituent elements of the second invention, the zoom lens and the focus lens are moved by the control of the control means. A prohibition means is provided to prohibit recording while the program is in progress.

[0018]

In the first aspect of the invention, the first control means causes the electronic zoom means to perform zoom control at the initial stage of zooming, and at the same time, the second drive means drives the focus lens. By performing the focus control, the non-focused state before zooming is changed to the focused state. Next, the selecting means takes over the zooming control at the initial stage by the first control means to perform zooming control, and when the control by the first control means ends, the selecting means controls the zoom lens and the focus lens. A locus in the storage means corresponding to a position is selected.

The second control means is the first control means.
Is controlled to move the zoom lens, and at the same time, the second drive means is controlled so that the focus lens moves following the zoom lens according to the locus selected in the in-focus state.

As described above, according to the first aspect of the invention, since the focus lens moves following the zoom lens in accordance with the locus selected in the in-focus state, the zoom lens is zoomed in the entire variation range of the scaling ratio without degrading the image quality. The focus control inside can be surely performed.

In the second invention, when the instructing means gives an instruction to move the lens based on the contents stored in the storage means, the control means moves the zoom lens to the position stored in the storage means. In addition to controlling the first driving means, the second driving means is controlled so as to move the focus lens to the focus position stored in the storage means.

As described above, according to the second aspect of the invention, both the position of the zoom lens and the in-focus position of the focus lens at an arbitrary point during shooting are stored, and both lenses are stored in the path of the shortest distance. Since it can be moved to the position, it is possible to shift to a previously stored photographing state at high speed.

According to a third aspect of the present invention, in addition to the same effect as the second aspect of the present invention, by the prohibiting means, an image which is blurred while the zoom lens and the focus lens are moving under the control of the control means is displayed. Recording is prohibited.

Therefore, for example, the focus control is performed while zooming while shooting while panning from the direction of a subject having another subject distance to the direction of a subject having a stored subject distance. Blurred images will not be played back, so you do not have to feel uncomfortable.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the first to third inventions will be described with reference to the drawings.

[First Embodiment of the Invention] FIG. 1 is a block diagram showing a schematic structure of a video camera according to an embodiment of the first invention.

The first fixed lens group 1, the zoom lens group 2,
The second fixed lens group 3 and the focus lens group 4 constitute an inner focus type lens system. In this lens system, when the zoom operation is performed by moving the zoom lens group 2, the focus lens group 4 has a so-called competition function that corrects the movement of the focal plane due to the movement of the zoom lens group 2 in addition to the focus adjustment function. Is also configured to fulfill.

FIG. 2 is a diagram showing a cam locus used when the focus lens group 4 performs the competition function. The horizontal axis represents the position of the zoom lens group 2 and the vertical axis represents the position of the focus lens group 4. The cam locus showing the positional relationship between the position of the zoom lens group 2 and the focus lens group 4 is shown for each subject distance.

This cam locus shows the locus of the in-focus position of the focus lens group 4 corresponding to the moving position of the zoom lens group 2, and when the zoom lens group 2 moves, the focus lens follows the cam locus. If the group 4 is controlled so as to follow the movement, the focus adjustment in a form in which the movement of the focal plane due to the movement of the zoom lens group 2 is corrected is realized. In this cam locus, actually, values sampled at predetermined intervals are preset in the EEPROM 5, and values at points other than the sampling points are obtained by interpolation processing.

An optical image incident through this lens system and the iris 6 is photoelectrically converted by the CCD 7, and a predetermined frequency component is removed from the photoelectrically converted video signal by the filter 8 and the signal is supplied to the signal processing circuit 9. Various signal processing is performed.

The micro computer 10 takes in the video signal output from the signal processing circuit 9 into a built-in memory (not shown), changes the read range of the image signal in this memory, and at the same time, with respect to the read image signal. Vertical direction,
Also, the angle of view (magnification) is changed by interpolating the signal in the horizontal direction, that is, electronic zooming is performed.

Further, the micro computer 10 recognizes the positions of the zoom lens group 2 and the focus lens group 4 based on the signals from the zoom encoder 11 and the focus encoder 12, respectively. After the zoom switch is operated, if a predetermined condition described later is satisfied, the zoom motor 14 is controlled to move the zoom lens group 2 in response to the operation of the switch. At this time, the cam locus corresponding to the recognized positions of the zoom lens group 2 and the focus lens group 4 is read from the EEPROM 5, and the focus lens group 4 follows the zoom lens group 2 according to the cam locus so as to move. It also controls the zoom motor 15. In addition, the micro computer 10
Adjusts the opening amount of the iris 6 while confirming the current position of the iris 6 by the signal from the iris encoder 16. As described above, the video camera is configured to perform both the electronic zoom and the optical zoom.

Further, the microcomputer 10 holds each peak value of the signal indicating the sharpness of the rising edge component and the falling edge component in both the vertical and horizontal directions of the video signal output from the signal processing circuit 9, By comparing these two peak values, it is determined whether the focus state or the non-focus state (front focus state or rear focus state) is determined. When it is determined that the focus state is achieved, the focus lens group 4 is moved and controlled so that both peak values are equal and the focus state is achieved.

Next, the focusing control operation during zooming, which is peculiar to the embodiment of the first invention, will be described with reference to the flowchart of FIG.

When the zoom switch 13 is operated, the micro computer 10 first executes the electronic zoom (step S31). Then, focusing control is performed based on the signal indicating the sharpness (step S32),
It is determined whether or not it is currently in focus (step S3).
3) As a result, if it is not in focus, step S32
Then, the focus control is continued.

On the other hand, if it is in focus, the cam locus corresponding to the current position of the zoom lens group 2 and the current position of the focus lens group 4 is selected and read from the EEPROM 5 (step S34). Then, the zoom motor 14 and the focus motor 15 are controlled so that the focus lens group 4 moves following the movement of the zoom lens group 2 according to the read cam locus (step S35), and the process ends.

As described above, in the embodiment of the first invention, the focus lens group 4 has the zoom lens group 2 according to the cam locus selected in the focused state, that is, the cam locus corresponding to the original original subject distance. To follow. Therefore, the image does not become out of focus during zooming. Moreover, since the zoom control is also optically performed, the image quality does not deteriorate. Further, since zoom control is electronically performed in the initial stage of zooming, the cam locus can be quickly selected and high-speed zooming can be performed even when zooming from the wide side to the tele side.

The first aspect of the invention is not limited to the above-described embodiment. For example, the cam locus is not selected after confirming the in-focus state, and the cam locus is obtained at a predetermined time after the start of zooming. May be selected.

[Embodiments of Second and Third Inventions] Next, embodiments of the second and third inventions will be described with reference to the drawings.

FIG. 4 is a block diagram showing a schematic structure of a video camera according to the second and third embodiments of the invention.

The lens barrel 41 includes a zoom lens group 4
2. A focus lens group 43 is provided. The zoom lens group 42 is meshed with a zoom screw 44, and this zoom screw 44 has a zoom motor 45.
By being rotated by, it is guided by the guide bar 46 and moves in the optical axis direction. The position of the zoom lens group 42 is detected by a zoom encoder 47 composed of a potentiometer, and its position signal (analog signal) is converted into a digital signal by an A / D conversion circuit 48 and input to a microcomputer 49. . The zoom motor 45 is drive-controlled by the PZ motor driver 50 under the control of the microcomputer 49.

The focus lens group 43 is supported by a rack 52 meshed with a focus screw 51. When the focus screw 51 is rotated by a focus motor 53, the focus lens group 43 is guided by a guide bar 54 and is guided in the optical axis direction. Move to. The position of the focus lens group 43 is detected as follows. That is, the position of the reset switch SW1 constituted by the photo interrupter is set as the initial position, and when the ON signal of the reset switch SW1 is input to the microcomputer 49 via the interface circuit 55, the microcomputer 49 causes the focus absolute address counter to be detected. FC (not shown) is reset to "0". And A
Every time a pulse signal is output to the F motor driver to rotate the focus motor 53 one step forward, the focus absolute address counter FC is incremented by one. The microcomputer 49 also has a zoom absolute address counter ZC for managing the position of the zoom lens group 42.

The microcomputer 49, in addition to the focus absolute address counter FC and the zoom absolute address counter ZC, the position of the zoom lens group 42 corresponding to the subject distance arbitrarily set by the user (hereinafter referred to as zoom registration position). A registration memory M (not shown) for setting and registering a focus position (hereinafter referred to as a focus registration position) of the focus lens group 43 corresponding to the zoom registration position. These settings are registered by operating the registration switch SW2. When the call switch SW3 is operated, the zoom lens group 42 and the focus lens group 43
Are moved to the zoom registration position and the focus registration position related to registration, respectively.

Next, the focusing control operation during zooming, which is peculiar to the second and third inventions, will be described with reference to the flowchart of FIG.

When the power is turned on, the microcomputer 49 first moves the focus lens group 43 to the initial position where the reset switch SW1 is present, and resets the focus absolute address counter FC to "0" (step S101). . Then, normal focusing (AF) control when the zoom SW1 is not turned on, zoom AF control when the zoom SW1 is turned on, and the like are performed (step S1).
02). At this time, the contents of the focus absolute address counter FC and the zoom absolute address counter ZC are updated each time the focus lens group 43 and the zoom lens group 42 are moved.

Next, it is determined whether or not the registration SW2 is turned on (step S103), and if it is not turned on, the process returns to step S102 to perform AF control and the like. On the other hand, if the registration switch SW2 is turned on, the focus absolute address in the current focus absolute address counter FC and the zoom absolute address in the zoom absolute address counter ZC are registered as the focus registration position and the zoom registration position, respectively, in the registration memory M. Is set and registered (step S104). Therefore, FIG.
As shown in FIG. 5, the photographer A points the video camera toward the subject B having the desired subject distance, and only turns on the registration switch SW2, whereby the zoom lens group 42 corresponding to the subject B having the desired subject distance is displayed. The position (desired magnification) and the in-focus position of the focus lens group 43 corresponding to the subject B having the desired subject distance under the magnification can be automatically registered.

Next, as shown in FIG. 7, "registering" is displayed on the finder to show the registered fact to the photographer (step S105). Then, it is determined again whether or not the registration switch SW2 is turned on in order to determine whether or not the photographer cancels the registered content and requests update registration (step S106). As a result, the registration SW2
Is not turned on, and if update registration is not requested at present, it is determined whether or not the call switch SW3 is turned on (step S107). As a result, if the call switch SW3 is not turned on, the process returns to step S106 to determine whether or not there is an update registration request.

On the other hand, if the call switch SW3 is turned on, it is determined whether or not recording is in progress (step S10).
8) If it is recording, stop recording (step S10)
9). A lens from the current position of the zoom lens group 42 and the current position of the focus lens group 43 (for example, the position corresponding to C in FIG. 7) to the zoom registration position and the focus registration position (for example, the position corresponding to B in FIG. 7). The moving direction is selected (step S110). On the other hand, if recording is not in progress, step S109 is skipped and the process proceeds to step S110 to select the lens moving direction.

Next, the PZ motor drivers 50 and A are moved so that the zoom lens group 42 and the focus lens group 43 are moved to the zoom registration position and the focus registration position, respectively.
The F motor driver 56 is controlled (step S11)
1). In this case, the movement destinations of both the zoom lens group 42 and the focus lens group 43 are known from the beginning, and the focus lens group 43 can be moved to the target position by the shortest path, so that focusing control during zooming is performed at high speed. In other words, it becomes possible to move to a pre-stored shooting state at high speed.

Then, it is judged whether or not the recording is in progress (step S112), and if the recording is in progress, the recording stop is released (step S113) and the process returns to step S106. If the recording is not in progress, immediately step S106 is performed. Return to. If it is determined in step S106 that the registration switch SW2 is turned on, it is considered that update registration has been requested, and the zoom registration position and focus registration position in the registration memory M are erased (step S114). ), And erases "Registering" displayed in the finder (step S11).
5) and returns to step S102.

As described above, when the focus control during zooming is performed, the recording is stopped, so that a blurred image is generated when the angle is changed from the position C to the position B in FIG. 6, for example. Is no longer played, so you don't have to feel uncomfortable. Moreover, since the recording is stopped and there is no fear that the motor sound is recorded, the lens can be moved to the registered position at high speed without worrying about the motor sound.

In this embodiment, the positions of the zoom lens and the focus lens at one time point are registered and stored. However, the positions of the zoom lens and the focus lens at a plurality of time points can also be registered and stored. It is possible. In this case, each time point is set to No. It is advisable to provide a plurality of call switches corresponding to each time point so that a desired shooting state can be designated quickly without designating such as.

[0053]

As described above in detail, in the present invention, since the focus lens moves following the zoom lens in accordance with the locus selected in the in-focus state, it is possible to reduce the zoom ratio without degrading the image quality. Focusing control during zooming can be reliably performed in the variation range. Further, since both the position of the zoom lens and the in-focus position of the focus lens at any time during shooting can be registered (stored), both lenses can be moved to the storage position by the shortest path, It becomes possible to quickly shift to a previously stored photographing state. Also, since recording is prohibited while focusing control is being performed during zooming, for example, while shooting while panning from the direction of a subject with another subject distance to the direction of a subject with a subject distance related to memory. Blurred images that occur when focus control is performed while zooming in are no longer reproduced, so discomfort is not required.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a video camera according to an embodiment of the first invention.

FIG. 2 is a diagram showing a cam locus used for focus control during zooming.

FIG. 3 is a flowchart showing a focusing control operation during zoom, which is peculiar to the embodiment of the first invention.

FIG. 4 is a block diagram showing a schematic configuration of a video camera according to embodiments of the second and third inventions.

FIG. 5 is a flowchart showing a focusing control operation during zoom, which is specific to the embodiments of the second and third inventions.

FIG. 6 is a diagram for explaining an example of registration of a position of a zoom lens corresponding to a predetermined subject distance and a focus position of a focus lens corresponding to the position of the zoom lens.

FIG. 7 is a diagram showing a display example on a finder during registration.

[Explanation of symbols]

 2, 42 ... Zoom lens group 4, 43 ... Focus lens group 5 ... EEPROM 7 ... CCD 9 ... Video signal processing circuit 10, 49 ... Microcomputer 11, 47 ... Zoom encoder 12 ... Focus encoder 13 ... Zoom switch 14, 45 ... Zoom motor 15,53 ... Focus motor SW1 ... Reset switch SW2 ... Registration switch SW3 ... Call switch

Claims (6)

[Claims] 1. A storage unit that stores a locus of a focus position of a focus lens corresponding to a plurality of positions of a zoom lens for each of a plurality of subject distances, a first driving unit that drives the zoom lens, and the focus. Second drive means for driving the lens, electronic zoom means for performing zoom control based on a captured video signal, and zoom control by the electronic zoom means at the initial stage of zooming, and at the same time as the second First, the focus lens is driven by the driving means for controlling focusing.
In performing zooming control by taking over the initial stage zooming control by the control means and the first control means, it corresponds to the positions of the zoom lens and the focus lens at the time when the control by the first control means is completed. Selecting means for selecting a locus in the storage means and moving the zoom lens by controlling the first driving means, and the focus lens follows the zoom lens according to the locus selected by the selecting means. And second control means for controlling the second drive means so as to move. 2. The video camera according to claim 1, wherein the first control unit performs the zoom control and the focus control until a focus state is achieved. 3. The video camera according to claim 1, wherein the first control means performs the zoom control and the focus control until a predetermined time elapses. 4. A storage unit that stores a position of the zoom lens and an in-focus position of a focus lens corresponding to the position of the zoom lens at an arbitrary point during shooting, and a first driving unit that drives the zoom lens. A second driving unit for driving the focus lens; an instruction unit for instructing a lens movement based on the stored contents of the storage unit; and a position stored in the storage unit in response to the instruction of the instruction unit. To move the zoom lens to the first
And driving means for controlling the second driving means so as to move the focus lens to the focus position stored in the storage means when the zoom lens moves. And a video camera. 5. The video camera according to claim 2, wherein
The video camera is provided with a prohibiting unit that prohibits recording while the zoom lens and the focus lens are moving under the control of the control unit. 6. The storage means stores a position of a zoom lens at an arbitrary plurality of time points during shooting and a focus position of a focus lens corresponding to the position of the zoom lens. Or the video camera according to claim 5.