JPH08228305A - Automatic focusing adjustment method of video tape recorder with camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize the change of a focus evaluation value to realize stable focusing by calculating a focus evaluation value calculation area corresponding to a zoom magnification to be set and automatically adjusting the focus based on the focus evaluation value obtained by adding a high frequency signal to it. SOLUTION: When a zoom magnification of a lens 10 is set, a CPU 70 takes a signal as the input to send a signal S of a focus evaluation value calculation area A to a lens control data processing part 60. The processing part 60 takes the signal S, horizontal and vertical synchronizing signals, and a clock signal as the input to calculate the area corresponding to the zoom magnification and adds the high frequency signal to the area A to output the focus evaluation value. Based on this focus evaluation value, the CPU 70 outputs automatic exposure and zoom magnification control signals to automatically control a stop driving part 80 and focus and zoom motor driving parts 90 and 100. Thus, the change of the focus evaluation value is minimized, and stable focusing is automatically executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for automatically adjusting the focus of a video tape recorder with a camera, and more specifically, in a device for automatically adjusting a focus of a video tape recorder with a camera having a zoom function, a change in the position of a subject. The present invention relates to a method for automatically adjusting the focus of a video tape recorder with a camera that minimizes a change in focus evaluation value and can perform stable focusing operation when only the zoom magnification changes.

[0002]

2. Description of the Related Art Generally, in a video tape recorder with a camera, there are two modes: a case where the angle of view of the focus evaluation value calculation area is fixed and a case where the angle of view of the focus evaluation value calculation area is not fixed. If the angle of view of the focus evaluation value calculation area is not fixed, the difference between the change stages is set to be large even if the focus evaluation value area changes, so the focus evaluation value is calculated according to the zoom magnification of the zoom lens. The contents of the screen were changing within the area. In addition, when the angle of view of the focus evaluation value calculation area is fixed, the focus motor is driven to search for the regular focus position where the focus evaluation position is the highest point, as shown in FIG. At this time, as shown in FIG. 6, when the position of the zoom lens moves when the focus motor is driven to a point that coincides with the normal focus position of the lens, the position of the zoom lens changes and the position of the screen within the focus evaluation value calculation area changes. The contents have changed, and the focus evaluation value of the normal focus becomes a different focus evaluation value, so that the focus motor is repeatedly driven.

[0003]

However, in the conventional automatic focus adjusting method for a video tape recorder with a camera, the contents of the screen change and the focus evaluation value changes during the process of automatically adjusting the focus. Therefore, there is an inconvenience that the automatic focus adjustment operation cannot be stably performed. In addition, there is a disadvantage that the focus evaluation value changes and the focus motor is driven unnecessarily in order to match the focus evaluation value with the positive focus evaluation value.

An object of the present invention is to increase or decrease the size of the focus evaluation value calculation area in proportion to the position of the zoom lens so that the focus evaluation can be performed even when only the zoom magnification changes without changing the position of the subject. An object of the present invention is to provide an automatic focusing method for a video tape recorder with a camera, which can perform stable focusing without changing the value.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to provide a video tape recorder with a camera having a zoom function for automatically adjusting the focus by utilizing the video signal within the angle of view of the focus evaluation value calculation area. First, check the zoom magnification set in the process of automatically adjusting the focus.
A step, a second step of determining a focus evaluation value calculation area corresponding to the set zoom magnification, and a first step of automatically adjusting the focus based on the focus evaluation value calculated in the determined focus evaluation value calculation area. It is achieved by providing an automatic focusing method for a video tape recorder with a camera, which is configured to perform three steps.

Tele / Wide (Tele / Wid) of the user
e) When the zoom magnification which is the position of the zoom lens is set by the switch operation, the focus evaluation value corresponding to the magnification of the zoom lens even if only the magnification of the zoom lens changes without changing the position of the subject. The calculation area is calculated, the high frequency signal is added to the calculated focus evaluation value calculation area,
A focus evaluation calculated value is calculated.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In the block applied to the automatic focus adjustment method for a video tape recorder with a camera according to the present invention, as shown in FIG. 1, a lens 10 for photographing a subject is used.
A fixed image sensor 20 that converts the amount of light incident from the lens 10 into an electrical signal; a color element signal detector 30 that classifies the signal output from the fixed image sensor 20 into color element signals; and a color element signal detector 30. An A / D conversion unit 40 for converting the analog color element signal output from the digital color element signal,
A video signal processing unit 50 that separates the digital color element signal output from the A / D conversion unit 40 into a luminance signal Y and a color signal C and outputs the signals as signals for displaying on a screen, and an external synchronization signal generator ( Applied from the lens control data processing unit 60 and the lens control data processing unit 60, which calculates the focus evaluation value from the output video signal of the A / D conversion unit by the synchronizing signal (Hsync, Usync, CLK) applied from (not shown). A central processing unit 70 that outputs a control signal for performing automatic focus adjustment based on an output focus evaluation value, a light amount input from the lens 10, and a zoom lens position adjustment signal input from an external tele / wide switch (not shown). A diaphragm drive unit 80 for adjusting the amount of light incident on a diaphragm (not shown) under the control of the central processing unit 70; and a focus control under the control of the central processing unit 70. A focus motor driver 90 for controlling the driving of the motor (not shown), and a zoom motor driver 100 for controlling the driving of the zoom motor (not shown), the the control of the central processing unit 70.

In the lens control data processing unit 60, a luminance signal generation unit 61 for separating the luminance signal Y from the applied digital color element signal and a high frequency transmitter 62 for outputting a high frequency signal from the separated luminance separation signal. And a synchronization signal (Hsync.
Vsync. CLK) and output from the central processing unit 70,
An addition area signal generator 63 that outputs an addition area signal according to an area signal SEC applied via an interface 66 described later, and an output signal of a high frequency transmitter 62 that is switched by the addition area signal of the addition area signal generator 63 are transmitted. Switch 64, a full adder 65 that adds the output signal of the high-frequency transmitter 62 to the focus evaluation value calculation area to calculate the focus evaluation value, and an addition area signal SEC applied from the central processing unit 70. Interface 66 for outputting the focus evaluation value output from the addition area signal generator 63 to the central processing unit 70.

The automatic focus adjustment method according to the present invention applied to the video tape recorder with a camera constructed as above will be described below. First, the light amount of the subject incident from the lens 10 is adjusted by a diaphragm (not shown), converted into an electrical signal by the solid-state image sensor 20, and then applied to the color element signal detection unit 30 to be converted into an analog signal. Color element signals are detected, applied to the A / D converter 40 to be converted into digital color element signals, and applied to the video signal processing section 50 and the lens control data processing section 60, respectively. Next, the digital color element signal is converted from the video signal processing unit 50 into the luminance signal Y and the color signal C and output as a screen display signal, and from the lens control data processing unit 60, the luminance signal converted high frequency signal. And the focus evaluation value calculation area signal output from the central processing unit 70, the focus evaluation value is calculated.

That is, in the first step, when the user operates the tele / wide switch to set the position (zoom magnification) of the zoom lens, the central processing unit 70 causes the zoom lens position output from the tele / wide switch. The focus evaluation value calculation area signal SEC is output by the adjustment signal, and the focus evaluation value calculation area signal SEC is applied to the addition area signal generator 63 through the interface 66 of the lens control data processing unit 60.

Then, in the second step, the addition area signal generator 63 applies the focus evaluation value calculation area signal SEC and the horizontal synchronization signal Hsy applied from the external synchronization signal generator.
nc, vertical sync signal Vsync, and clock signal CLK
After the addition region signal is output by and, the switch 64 is turned on, and the high frequency signal output from the high frequency transmitter 62 is applied to the full adder 65. Then, the full adder 65
As shown in FIG. 3, the user operates the tele / wide switch to move the zoom lens to the B area in the tele state or the A area in the wide state, or the normal photographing area C between the A area and the B area. If you set the zoom lens position,
A focus evaluation value calculation area corresponding to the areas A, B, and C is calculated, and the high-frequency transmitter 62 is added to the calculated focus evaluation value calculation area.
The focus evaluation value is calculated by adding the output high frequency signals from the. In this case, the focus evaluation value calculation area differs depending on the zoom lens position adjustment signal applied through the tele / wide switch, and the size of the focus evaluation value calculation area is as shown in FIG. It is increased in proportion to the magnification of a certain zoom lens.

Next, as a third stage, the full adder 65
Outputs the calculated focus evaluation value to the central processing unit 70 through the interface 66, and the central processing unit 70 performs automatic focus adjustment based on the applied focus evaluation value and the light amount input from the lens 60. A control signal for the exposure and the zoom lens magnification is output to drive the diaphragm drive unit 80, the focus motor drive unit 90, and the zoom motor drive unit 100, respectively, to automatically adjust the focus.

[0013]

As described above, in the automatic focus adjusting method for the video tape recorder with a camera according to the present invention, the size of the focus evaluation value calculation area is proportionally increased or decreased according to the position change of the zoom lens, and the object is calculated. Even if only the zoom magnification changes without changing the position of, the contents of the screen in the focus evaluation value calculation area do not change, so changes in the focus evaluation value are minimized and stable. There is an effect that focusing can be performed to prevent unnecessary driving of the focusing Shingo motor.

[Brief description of drawings]

FIG. 1 is a block diagram to which an automatic focusing method for a video tape recorder with a camera according to the present invention is applied.

FIG. 2 is a block diagram of a lens control data processing unit applied to the automatic focus adjustment method according to the present invention.

FIG. 3 is a view showing a setting state of a focus evaluation value calculation area according to the present invention.

FIG. 4 is a graph showing the size of a focus evaluation value calculation area with respect to the position of the zoom lens according to the present invention.

FIG. 5 is a graph showing a position of regular focus with respect to a position of a conventional zoom lens.

FIG. 6 is a graph showing a change in focus evaluation value with respect to the position of a conventional zoom lens.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Lens 20 ... Solid-state image sensor 30 ... Color element signal detection part 40 ... A / D conversion part 50 ... Video signal processing part 60 ... Lens control data processing part 61 ... Luminance signal generator 62 ... High-frequency transmitter 63 ... Addition area Signal generator 64 ... Switch 65 ... Full adder 66 ... Interface 70 ... Central processing unit 80 ... Aperture drive unit 90 ... Focus motor drive unit 100 ... Zoom motor drive unit

Claims (2)

[Claims] 1. An automatic focus adjustment method for a video tape recorder with a camera, which has a zoom function for automatically adjusting the focus by using a video signal within the angle of view of a focus evaluation value calculation area, wherein: A first step of checking the zoom magnification set in the process of adjusting the focus; a second step of determining a focus evaluation value calculation area corresponding to the set zoom magnification; and the determined focus evaluation value. An automatic focus adjustment method for a video tape recorder with a camera, which sequentially performs a third step of automatically adjusting the focus based on the focus evaluation value calculated in the calculation area. 2. The automatic focus adjustment method for a video tape recorder with a camera according to claim 1, wherein the focus evaluation value calculation area is increased or decreased in proportion to a zoom magnification.