JPH06319070A - Video camera - Google Patents

Abstract

PURPOSE:To automatically set up a video camera to an operation state prevented from generating malfunction at the time of taking a picture in the lighting state of a video light. CONSTITUTION:At the time of taking a picture in the lighting state of the video light, a focus control means (a microcomputer 19) fixes an automatic focusing evaluating range on the center part of a photographing screen based upon the detection result of a video light use detecting means (the microcomputer 19 and a power supply current detecting circuit 26) to set up a center part emphasizing type focusing control. On the other hand, an exposure control means (the microcomputer 19) sets up the luminance detection system of a photographing video signal to a peak detection system based upon the detection result of the video light use detecting means to reduce back flow correction. Then a white balance control means (the microcomputer 19) restricts a white balance adjusting range to the color temperature range of the video right based upon the detection result of the video light use detecting means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera such as a camera-integrated VTR.

[0002]

2. Description of the Related Art Conventionally, a video camera of this type such as a VTR with a built-in camera is designed to CC an optical image of a subject through a photographing lens.
An image pickup device such as a D solid-state image pickup device receives light, and a video signal (photographed video signal) of the image pickup device is processed to form a recording signal or the like.

Further, in order to obtain a good result by so-called normal mode automatic control photographing, an auto focus (hereinafter referred to as AF) function and an automatic exposure (hereinafter referred to as AE)
Function and auto white balance (hereinafter AWB
Called) function. These functions are usually set to cover shooting under outdoor sunlight and general indoor lighting such as a fluorescent lamp and an incandescent furnace, and are realized by using a microcomputer.

Next, referring to FIG. 1 corresponding to one embodiment of the present invention.
A conventional video camera of this type will be described with reference to FIG. FIG. 1 shows the configuration of a camera-integrated VTR, in which image pickup light of a subject is received by a CCD solid-state image pickup device 3 via a taking lens 1 and a diaphragm (iris) 2.

The color video signal (photographed video signal) of the photographic screen of each field of the image pickup device 3 obtained by this light reception is supplied to the signal processing circuit 5 via the AGC circuit 4.

The color separation circuit 6 of the signal processing circuit 5 converts the picked-up image signal into three primary color signals of R, G, B, and these three primary color signals are G, for white balance adjustment.
It is supplied to the matrix circuit 9 through the amplifiers 7 and 8 of B, is reconfigured into a video signal by the circuit 9, and is supplied to the recording circuit unit and the like in the subsequent stage of the signal processing circuit 5.

The luminance signal (Y) of the photographed video signal output from the image pickup device 3 is supplied to a bandpass filter 10 for extracting a high frequency component and a lowpass filter 11 for extracting a low frequency component, and both filters 10, The output signal of 11 is the AF of the analog switch 13 for input selection of the evaluation signal forming unit 12.
It is supplied to the contact 13a and the AE contact 13b.

Further, the RY and BY color difference signals output from the matrix circuit 9 are passed through the low-pass filters 14 and 15 for extracting the low-frequency components to the analog switch 13-2.
It is supplied to the individual AWB contacts 13c and 13d. And
The analog switch 13 has a contact 1 at a field cycle, for example.
The signals of the contacts 13a to 13d are digitized by the A / D converter 16 and then taken into the microcomputer 19 via the screen division circuit 17 and the digital integration circuit 18.

This microcomputer 19 is set to A when the analog switch 13 switches to the contacts 13a and 13b.
The processing of F and AE is executed, the processing of AWB is executed when switching to the contacts 13c and 13d, and the processing of each function is performed in a time division manner. That is, the microcomputer 19 controls the screen division circuit 1 according to the function to be executed and the setting of the photographing mode.
7 is set to set the signal capturing range (evaluation area) of each of the contacts 13a to 13d to the entire photographing screen or a part such as the central portion.

Then, the contacts 13a and 13b in the evaluation area
Is taken into the microcomputer 19 as a signal of the evaluation value of AF and AE, and the signals of the contacts 13c and 13d are taken as a signal of the evaluation value of AWB.
Be taken into.

Based on these signals, the AF function formed by the microcomputer 19 and the motor drive circuit 20,
An AE function formed by the microcomputer 19 and the diaphragm control unit 21, the microcomputer 19 and the amplifier 7,
Each of the AWB functions formed by 8 operates as described below.

AF function The microcomputer 19 detects a high-frequency change in the brightness of the photographed video signal from the AF evaluation value signal based on the signal from the contact 13a to evaluate the current focus state, and based on this evaluation, the focus motor. A focus control signal is output to the drive circuit 20.
Then, the focusing motor drive circuit 2 is driven by this focusing control signal.
0 is driven by a motor to bring the taking lens 1 into a focused state.

At this time, in order to perform an appropriate evaluation according to the shooting condition, the evaluation area is switched to a large range including the peripheral portion and a small range only for a part such as the central portion according to the shooting condition.
The focus control method changes due to the change in the evaluation area.

The AE function microcomputer 19 variably sets the exposure reference value in consideration of automatic or manual backlight compensation in the evaluation of the luminance of the photographed video signal based on the signal of the contact 13b, and sets the voltage signal Vref of this reference value. It is supplied to the aperture control circuit 21.

This control circuit 21 is conventionally constructed as shown in FIG. 3, and the luminance signal (Y) output from the solid-state image pickup device 3 is supplied to the base of an input transistor 22 as an iris luminance signal. An emitter current corresponding to the base input of the transistor 22 flows into the capacitor C1 via the resistor R1 of the detection time constant circuit 23, and the capacitor C1 is charged.

Furthermore, the emitter voltage of the output transistor 24 is changed by the charging voltage corresponding to the detected brightness of the capacitor C1, and the difference between this emitter voltage and the reference voltage signal Vref is the operational amplifier 25 and the resistor R2. The iris control signal is formed by being integrated by the integrator of the capacitor C2, and the diaphragm 2 is controlled by this signal to set the exposure according to the brightness of the subject. Note that R in FIG.
3, R4 are emitter resistances of the transistors 22 and 24, 2
6 is a + 5V power supply terminal.

The luminance detection method for determining the response characteristic is set by the time constant R1 × C1, and this time constant is
Usually, it is set to be relatively large so that the entire screen can be seen on average. Therefore, the luminance detection method is conventionally set to the average detection method.

AWB function The microcomputer 19 determines the color temperature of the object by discriminating the color information of the photographed video signal from the evaluation values of the RY and BY color difference signals based on the signals of the contacts 13c and 13d.
Then, for example, a gain control signal in the PWM signal format is supplied to the amplifiers 7 and 8 so as to adjust the white balance according to the color temperature, and the gains of the amplifiers 7 and 8 are variably set to adjust to a good white balance. .

At this time, in order to make the adjustment range of the white balance as wide as possible, it is usually 2800 to 6400.
A wide color temperature range of about K is set as the adjustment range. The resistors Rx and Ry and the capacitors Cx and Cy in FIG.
These are resistors and capacitors for filters provided on the gain control signal lines of the amplifiers 7 and 8.

[0020]

In the case of the conventional video camera of this kind, when the video light is turned on in the normal mode to take a picture, the AF function and the AE are explained as follows.
There is a problem that the function and the AWB function each malfunction to prevent proper shooting. That is, when shooting with the video light turned on, the subject of interest is usually located only in the center of the screen.

With respect to the AF function, if the evaluation range is large, a focusing error or the like occurs due to the influence of an unnecessary subject around the screen. Next, regarding the AF function, since the aperture control circuit 21 detects the brightness of the subject by the average detection method, for example, the subject in the central portion becomes too bright due to the influence of the dark portion around the screen.

Moreover, if the backlight correction is performed, there is a possibility that the correction of unnecessary brightness may be added to the subject in the central portion by this correction. Next, regarding the AWB function,
Since the adjustable color temperature range is wide, for example, if there is a monochromatic spotlight light source around the screen, the white balance of the subject in the central portion cannot be achieved due to the influence of this light source.

In order to solve the above inconveniences, it is conceivable to manually switch the shooting mode to a special mode when shooting with the video light turned on to change the operation of each function. The specific operation (control) of each function in such a mode has not been invented, and if the shooting mode is manually switched, the operability may deteriorate and an operation error may occur. The present invention automatically sets the AF function, A
The purpose is to set the E function and AWB function to the state where no malfunction occurs.

[0024]

In order to achieve the above object, in the video camera of the present invention, in the case of claim 1, a video light use detecting means for detecting a photographing state in which a video light is turned on, and Focus control means for fixing the focus range of the autofocus to the center part of the shooting screen and setting the focus control of the center part focus system based on the detection result of the detection part when shooting with the video light turned on. .

According to the present invention, the video light use detection means for detecting the photographing state in which the video light is lit, and the photographed video signal when the video light is lit and photographed based on the detection result of this detection means. And an exposure control means for reducing backlight compensation while setting the luminance detection method to the peak detection method.

Further, in the case of claim 3, the video light use detecting means for detecting the photographing state in which the video light is turned on, and the adjustment range when the video light is turned on for photographing are detected based on the detection result of the detecting means. A white balance control means for limiting the color temperature range of the video light.

[0027]

In the case of the video camera of the present invention configured as described above, first, in the configuration of claim 1, when shooting with the video light turned on, the focus is detected based on the detection result of the light use detection means. The control means automatically fixes the evaluation range of the autofocus at the center of the screen where the subject of interest is located, and the center-focused focusing control is performed. Therefore, the subject in the central portion of the screen is accurately focused without being affected by an unnecessary subject in the peripheral portion of the screen.

Further, according to the second aspect of the present invention, when the video light is turned on and the image is taken, the exposure control means automatically detects the brightness of the picked-up video signal based on the detection result of the light use detection means. The peak detection method is set to control the exposure according to the brightness of the subject in the center of the screen illuminated by the video light, and reduce backlight compensation. Therefore, it is possible to perform proper exposure control by eliminating the influence of the brightness of unnecessary portions such as the peripheral portion of the screen and the influence of backlight compensation.

Further, according to the third aspect of the present invention, when the video light is turned on for shooting, the color temperature range in which the white balance can be adjusted is automatically adjusted based on the detection result of the light use detection means. It is limited to the color temperature range and misadjustment due to a light source having a color temperature outside the range is prevented. Therefore, it is possible to properly adjust the white balance of the subject in the central portion of the screen without being affected by the spotlight in the peripheral portion of the screen.

[0030]

EXAMPLE One example will be described with reference to FIGS. First, in this embodiment, one battery (battery) is shared by the power source of the camera-integrated VTR and the power source of the video light to reduce the number of batteries to carry,
In addition, in order to easily detect the lighting of the video light, when the video light is lit for shooting, the video light is attached to the accessory shoe of the VTR and power is supplied to the video light from the power supply circuit of the VTR via the accessory shoe. .

In FIG. 1, the points different from the conventional configuration are the following points (a) to (c). (A) A power supply current detection circuit 26 is provided, and a large current when the video light is lit is detected by this circuit 26 and a lighting detection signal is supplied to the microcomputer 19.

(A) The microcomputer 19 is provided with the following means (i) to (iv). (I) Lighting and photographing detection means that forms a video light use detection means together with the power supply current detection circuit 26. (Ii) Focus based on the detection result of the lit shooting detection means, when the video light is lit and shooting is performed, the evaluation range of autofocus is fixed to the center of the shooting screen and the focus control is set to the center-weighted focusing method. Control means.

(Iii) Exposure control for setting the brightness detection method of the aperture control circuit 21 to the peak detection method and reducing backlight compensation based on the detection result of the lit shooting detection means when shooting with the video light turned on. means. (Iv) White balance control means for limiting the adjustment range to the color temperature range of the video light based on the detection result of the lighting photographing detection means.

(C) Time constant circuit 23 of aperture control circuit 21
In addition, as shown in FIG.
Also, a resistor R5 is provided which is connected in parallel with the resistor R1 when the transistor 27 is turned on to reduce the detection time constant. Note that R6 and R7 in FIG. 2 are the base input resistance and the emitter-base bias resistance of the transistor 27. When shooting in the normal mode without turning on the video light, the same AF, AE, and AWB controls as in the related art are performed.

Next, when shooting with the video light turned on in the normal mode, the power supply current detection circuit 26 supplies the lighting detection signal to the microcomputer 19 based on the lighting of the video light, and the microcomputer based on this supply. The lighting photographing detection means 19 detects that photographing is performed using a video light.

Then, based on this detection, the photographing mode of the microcomputer 19 becomes the video light mode. By changing this mode, the AF function, the AE function and the A function are set.
The operation of each WB function is automatically changed as described below.

AF Function When in the video light mode, the microcomputer 1
The focus control means 9 controls the screen division circuit 17 so as to fix the evaluation area to a small area in the center of the screen, and automatically sets the focus control of the center-focused method. As a result, the influence of an unnecessary subject in the peripheral portion of the screen is eliminated, a focusing error or the like is prevented, and the subject in the central portion of the screen is accurately focused.

Further, in this embodiment, in order to prevent the focusing error more reliably, the focus control means of the microcomputer 19 also changes the threshold value for the restart determination. That is, after focusing, the evaluation value signal is lowered below the threshold value for the judgment of the microcomputer 1.
Reference numeral 9 detects a shift in focus due to movement of the subject and restarts focus control.

In general, the threshold value for the determination is set to a relatively small value in order to improve the focus responsiveness.
When it comes to the video light mode, we focus on the stability of operation,
The threshold value for the determination is changed to a value higher than usual in order to prevent unnecessary focusing control for a “obstruction” or the like in which something crosses in front of the subject of interest.

AE function When the video light mode is entered, the microcomputer 1
The exposure means 9 supplies the diaphragm control circuit 21 with a high-level switching signal SW for switching the detection method.
As a result, the transistor 27 of the aperture control circuit 21 is turned on to decrease the time constant of the detection time constant circuit 23, and the detection of the luminance of the iris luminance signal is switched from the normal average detection method to the peak detection method, and the brightness of the subject is reduced. Is detected by the peak detection method.

As a result, the diaphragm 2 changes in accordance with the change in the brightness of the subject in the center of the screen illuminated by the video light.
The control motor of 1 operates more than before, and the amount of light is sufficiently suppressed to reduce and eliminate the influence of the brightness of the peripheral portion of the screen. Further, in order to reduce the effect of unnecessary backlight correction, the exposure control means corrects the voltage signal Vref of the reference value of the microcomputer 19 while switching the detection method.
The effect of backlight compensation is also prevented.

AWB Function When in the video light mode, the microcomputer 1
The white balance control means 9 limits the variable gain range of the amplifiers 7 and 8, and the adjustable white balance color temperature range is limited to a range of about 2800 to 3200K near the color temperature 2800K of the video light. As a result, erroneous control of white balance due to other spotlights or the like is prevented.

Further, in this embodiment, in order to prevent erroneous control more reliably, the white balance control means changes the threshold value of the white balance evaluation in the microcomputer 19, and once the white balance is obtained, the white balance is easily adjusted. Prevents readjustment. Since each function is automatically changed by the microcomputer 19, the optimum focus control and exposure control suitable for shooting are performed when shooting with the video light turned on without manually switching the shooting mode. And white balance adjustment is performed.

By the way, in the above embodiment, only the diaphragm 2 is controlled by the AE function, but not only the diaphragm 2 but also the signal gain,
You may make it control an electronic shutter etc. It can also be applied to the case where the power source for the video light is prepared separately from the power source for the VTR. In this case, instead of the power source current detection circuit 26, for example, a circuit for detecting the power-on of the video light is provided. Good.

And not only the VTR with a built-in camera,
Of course, it can be applied to various video cameras. In this case, the video camera may have any one or more of the AF function, the AE function, and the AWB function.
When only the F function is provided, the video light use detection means and the focus control means may be added.

[0046]

Since the present invention is configured as described above, it has the following effects. First, in the case of claim 1, when shooting with the video light turned on,
Based on the detection result of the light use detection means, the focus control means automatically fixes the evaluation range of autofocus to the center of the screen where the subject of interest is located, and the focus control of the center-weighted method is performed. Focus on the subject in the center of the screen with high accuracy without being affected by unnecessary subjects, and automatically perform optimal focusing control according to the shooting situation without switching shooting modes. It is possible to prevent deterioration of operability and operation mistakes and perform good shooting.

Next, in the case of claim 2, when the video light is turned on and a picture is taken, the exposure control means automatically detects the brightness of the picked-up video signal based on the detection result of the light use detection means. The peak detection method is set and the exposure is controlled according to the brightness of the subject in the center of the screen where the video light is emitted. In addition, proper exposure control can be performed by eliminating the influence of the brightness of unnecessary portions such as the peripheral portion of the screen and the influence of backlight compensation, and it is possible to prevent deterioration of operability and operation mistakes and perform good shooting.

Further, in the case of claim 3, when the video light is turned on and the image is taken, the adjustable color temperature range is limited to the color temperature range of the video light based on the detection result of the light use detection means. The white balance is adjusted by preventing the adjustment error due to the light source of the color temperature out of the range, and it is possible to automatically perform the white balance adjustment without malfunction without changing the shooting mode. Deterioration and operation mistakes can be prevented and good shooting can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a video camera of the present invention.

FIG. 2 is a detailed connection diagram of a part of FIG.

FIG. 3 is a detailed connection diagram of a part of a conventional device.

[Explanation of symbols]

 1 Photographic lens 2 Aperture 3 CCD solid-state image sensor 12 Evaluation signal forming unit 19 Microcomputer 20 Focusing motor drive circuit 21 Aperture control circuit 26 Power supply current detection circuit

Claims (3)

[Claims] 1. A video light using a video light for detecting a shooting state in which a video light is turned on in a video camera having an autofocus function for controlling focus of a shooting lens according to a brightness change of a shooting video signal in an evaluation range set on a shooting screen. Based on the detection result of the detection means, a focus control for fixing the evaluation range to the center part of the shooting screen and setting the focus control of the center part focus method when shooting with a video light turned on. A video camera having means. 2. A video camera equipped with an automatic exposure function for controlling shooting exposure by detecting the brightness of a subject based on the detection of the brightness of a shooting video signal and backlight compensation, and detects a shooting state in which a video light is turned on. And a video light use detection means for controlling the brightness, and an exposure control means for setting the brightness detection method to the peak detection method and reducing backlight compensation when shooting with the video light turned on based on the detection result of the detection means. Video camera characterized by having. 3. A video light use detecting means for detecting a shooting state in which a video light is turned on in a video camera having an automatic white balance function for adjusting a white balance according to a color temperature of an object based on color information of a shooting video signal. And a white balance control means for limiting the adjustment range when the video light is turned on for shooting to the color temperature range of the video light based on the detection result of the detection means.