JPS6341473B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color video camera that constitutes a portable video system in combination with a video tape recorder or the like.

Some color video cameras have traditionally been equipped with an auto white balance device to compensate for the white balance of the reproduced image being distorted due to differences in the color temperature of the illumination light source in the scene being photographed. When capturing (recording) images using a color camera, focus the image of a subject such as white paper on the shooting target surface, or cover the lens with a cap made of a milky white light diffusion plate and operate the auto white balance button. The method of doing so was used. According to these conventional methods, it is cumbersome to operate during actual shooting.
It was easy to end up taking pictures without adjusting the white balance accordingly. In addition, in order to save power consumption, the camera is turned off when not in use and turned on only when taking pictures.In such cases, conventional auto white balance circuits The white balance changed every time I turned it off and on, and I had to operate the white balance switch every time.

An object of the present invention is to provide a color video camera that eliminates the drawbacks of the conventional device as described above.
The white balance is automatically adjusted each time you
The configuration is such that recording by a video recording device (VTR) is started after this white balance adjustment is completed. This allows the correct white balance to be re-established for each shooting scene, making it possible to record images with perfect color balance without being aware of changes in color temperature under any environment during recording. be.

The present invention will be explained in detail below with reference to the drawings. FIG. 1 shows an example of an automatic white balance circuit for a conventional color television camera. To briefly explain this operation, the red signal R obtained at the red signal input terminal 1 passes through the gain control amplifier circuit 2, the red process circuit 3, and is sent to the encoder circuit (not shown) and the GR color difference calculation circuit 4. It will be done. The green signal G obtained at the green signal input terminal 5 passes through an amplifier circuit 6 and a green process circuit 7, and is sent to an encoder circuit (not shown), a GR color difference calculation circuit 4, and a GB color difference calculation circuit 11. The blue signal B input to the blue signal input terminal 8 passes through a gain control amplifier circuit 9, a blue process circuit 10,
The signal is distributed and sent to an encoder circuit (not shown) and the G-B color difference calculation circuit 11. The output signal of the GR color difference calculation circuit 4 is amplified by the differential amplifier circuit 12 and converted to DC by the DC conversion circuit 12 ₁ . Also G-B
The output signal of the color difference calculation circuit 11 is sent to the differential amplifier circuit 13.
The signal is amplified by the DC converter circuit ₁₃₁ and converted to DC by the DC conversion circuit 131. Here, when the white balance circuit selector switch S is set to the "manual" side M, the -B voltage is applied to the gate of the field effect transistor (hereinafter referred to as EET) _Q1 .
It is cut off, and current does not flow through relay R ₁ either, so relay contacts R _1A and R _1B are open. Transistor Q ₃ is also cut off, so no current flows through relay R ₂ and relay contacts R _2A and R _2B are closed, so the automatic white balance circuit is grounded. In this state, when you point the TV camera at a white subject and switch switch S to "auto" side A, the voltage on one side of capacitor C ₁ (switch S side) changes from -B to +B, and the gate of FETQ ₁ momentarily changes. +
Biased in the voltage direction, FET Q ₁ conducts for a time determined by the time constant of C ₁ and R ₁ , and at the same time, relay R ₁ operates and contacts R _1A and R _1B close. Transistor Q ₃ also conducts, relay R ₂ operates, and contacts R _2A ,
Since _R2B is open, the automatic white balance circuit forms a loop, and the output signals of the differential amplifier circuits 12 and 13 at that time are the G-R signal memory circuit 14,
The signal is transmitted to the G-B signal memory circuit 15 and stored. The red gain control amplifier circuit 2 is controlled by the GR DC output signal of the GR signal memory circuit 14,
Adjust the red process output signal level to the green process output signal level. The G-B DC output signal from the G-B signal memory circuit 15 similarly controls the blue gain control amplifier circuit 9, and automatically adjusts the white balance by equalizing the levels of the red, green, and blue signals of each process circuit 3, 7, and 10. match the target. Here, FET Q ₁ starts discharging with a time constant of C ₁ and R ₁ , and eventually returns to cut-off and contacts R _1A and R _1B open, but memory circuits 14 and 15
The DC output voltage remains the same, and the TV camera maintains a white balanced state.

However, when the camera power is turned off and then turned on again in this state, switch S is set to the "auto" side, so at the moment when the power is turned on, +B voltage is applied to switch S, and the gate of FET Q ₁ is in the + voltage direction. is charged and conductive, relay K ₁ operates, contacts R _1A and R _1B close, and the automatic white balance circuit is activated. (Meanwhile, relay R ₂ is conductive and contacts R _2A and R _2B remain open.) However, at the moment when the power is turned on, the beam current of the image pickup tube is not flowing through the television camera enough, and the red and blue , the green beam current is uneven, and the red, blue, and green process output levels are also uneven, in a transient state. Since the white balance is maintained in this state, the white balance will collapse completely when the camera returns to a steady state.

As explained above, in the conventional automatic white balance adjustment circuit of a television camera, the white balance is distorted every time the power is turned on, so it was necessary to find a suitably white subject and press the white balance changeover switch S again.

Also, the signal of trigger switch T is inverter _Q4
The signal is input to the VTR start circuit 16 via. Therefore, when trigger switch T is turned on, H
The signal will be input to the VTR start circuit in a known manner.

Although the above explanation was for a three-tube type television camera, in the case of a single-tube type camera, the green signal G is replaced with the brightness signal Y. Therefore, in the conventional example shown in FIG. 11, changing the photographing scene requires a troublesome procedure of switching the white balance changeover switch S to the M side to adjust the white balance, and then starting photographing. In order to solve these drawbacks, the present invention allows the white balance to be adjusted automatically by pressing the first step of the camera's trigger lever, and then automatically adjusts the white balance automatically. The configuration was such that the second stage for shooting was pressed after adjustment was completed. Also, unlike the method of finding a white subject and adjusting the white balance, by providing a milky-white lighting window outside the camera, it is possible to adjust the white balance not only for white subjects but also for any subject. It has a structure. With this configuration of the present invention, there is no need for complicated procedures for each shooting scene as described above in the conventional example, and simple operations such as pushing the trigger lever to the first step and then to the second step can be used. ,
It becomes possible to start shooting with the white balance adjusted. Furthermore, one of the major features of the present invention is that the photographing switch linked to the above-mentioned second stage trigger is prohibited while the white balance is being adjusted. FIG. 2 is a circuit connection diagram showing an embodiment of an auto white balance circuit for a color video camera according to the present invention. In FIG. 2, only the relay drive circuit and trigger circuit that are directly related to the present invention are extracted and illustrated from the system diagram of the conventional white balance circuit shown in FIG. As shown in FIG. 3, which will be described later, the switch _T1 , which is turned on by the first depression in conjunction with the trigger button, is disposed between the power supply +B and the automatic side A of the switch S. Also, the signal of switch R _1C linked to the operation of relay R ₁ is the first
The second stage switch of the trigger mentioned in the figure
The signal from _T2 is input to the AND circuit _Q5 , and its output is output to the VTR start circuit mentioned above.

FIG. 3 is a schematic diagram showing one embodiment of the configuration of a color video camera according to the present invention. In the figure 1
01 is a video camera case, 102 is a lens, 10
3 is a grip, and 104 is an imaging tube.

Next, the operation will be explained with reference to the drawings. Slideable trigger lever 10 biased by spring 106 by pressing trigger button 105
Step 7 first turns on trigger switch _T1 . Due to this switch operation, the blocking wall 1 that was blocking the light from the outside light window 101' provided above the lens
08 is moved from the optical path by a plunger, lever link mechanism, etc., although not shown in detail. Due to this movement, the light from the outside light window 101' is directed to the diffuser plate 109, the condensing lens 110, and the reflecting mirror 111.
The image is guided to the image pickup tube 104 by a half mirror 112, and white balance is taken.

Further, by stroking the trigger button 105, the trigger switch _T2 is turned on, and after confirming that the white balance has been achieved, the magnetic recording/reproducing device (not shown) starts recording.

Camera exterior lighting window 10 of the present invention shown in FIG.
1' is placed above the lens parallel to the optical axis, but this window may also be placed on the top of the camera. In addition, without separately providing such an external lighting window, a structure is adopted in which a milky white plate is inserted and retracted between the lens 110 and the image pickup tube 104 in conjunction with the trigger switch _T1 , and the light passing through the lens 110 is inserted and retracted. After adjusting the white balance using light, quickly remove the milky white plate and then turn the trigger switch.
Recording may be started by T ₂ .

In the configuration shown in Fig. 3, when the first stage trigger switch _T1 for white balance adjustment is turned on, the external changeover switch S has already been switched to the automatic side A, so as explained in the conventional example shown in Fig. 1. ,relay
R ₁ operates for a time determined by the time constant of C ₁ − r ₁ ,
Relay R ₂ operates simultaneously when switch T ₁ is turned on.
This causes the white balance adjustment circuit to operate. At this time, relay switch R _1C linked to relay R ₁ is also turned on for this time, and AND circuit Q ₅
An L level signal is output to. Eventually,
The white balance adjustment circuit operates within the time constant of C ₁ - _{r 1} .
Once the adjustment is complete and relay R ₂ is deactivated again,
Switch _R1C is also turned off, and an H level signal is output to AND circuit _Q5 . Next, when the second stage trigger switch _T2 is turned on, H is input to the second input terminal of AND circuit _Q5 via inverter _Q4 , and H is output as the output of AND circuit _Q5 .
The VTR start circuit 16 is turned on and shooting (recording) is started. Also rapidly trigger button 10
Even if you press 5 and turn on switches T ₁ and T ₂ almost at the same time, the output of AND circuit Q ₅ will not become H while relay R ₁ for white balance adjustment is operating.
The output becomes H only after the white balance adjustment is completely completed. This makes it possible to prevent erroneous operations such as starting shooting even though adjustments have not yet been completed.

FIG. 4 is a main circuit connection diagram showing another embodiment of the present invention, in which the external automatic/manual changeover switch shown by S in FIG. It is constructed using an automatic changeover switch 4 which can be operated manually when the button 105 is not pressed, and automatically when the trigger button of the camera is pressed.

That is, in the embodiment shown in the second figure, automatic white balance adjustment is performed only when the external white balance automatic/manual changeover switch S is set to the automatic side A, and the switch _T1 linked to the first stage of the trigger button is on. However, in the circuit shown in Figure 4, the auto white balance adjustment circuit is activated only by switch T ₄ which is linked to the first stage of the trigger button, and when this switch T ₄ is not activated, the white balance is always adjusted. This configuration allows for manual balance adjustment.

As described in detail in the embodiments above, in the present invention, the white balance can be adjusted by pressing down the trigger button of the camera in the first step.
This allows the camera to start shooting once the white balance adjustment is completed, making it easier to operate the camera, and making it possible to adjust the white balance without fail. It can be made extremely convenient for operation.

[Brief explanation of drawings]

Figure 1 is a circuit connection diagram showing an example of a white balance adjustment circuit in a conventional color video camera.
The figure is a circuit connection diagram showing an embodiment of an automatic white balance adjustment circuit for a color video camera according to the present invention.
FIG. 3 is a schematic diagram showing one embodiment of the configuration of a color video camera according to the present invention, and FIG. 4 is a main circuit connection diagram showing another embodiment of the present invention. 101...Camera body, 102...Photographing lens, 1
03... Grip, 104... Image pickup tube, 105... Trigger button, 106... Spring, 107... Trigger lever, 108... Light shielding wall, 109... Light diffusing plate, 11
0...Condenser lens, 111...Reflection mirror, 112...
Half mirror, 101'...External lighting window, S...Auto/manual switch, T ₁ ...White balance trigger switch, T ₂ ...Photographing (recording) trigger switch.

Claims (1)

[Claims] 1. Forming a detection signal according to the color temperature of the subject,
In a color video camera equipped with a white balance adjustment means for adjusting white balance according to the detection signal, a recording device for recording an output signal of the camera, and a trigger operation member for starting recording by the recording device. interlocking recording switch means; means for automatically fetching the detection signal into the white balance adjusting means prior to operation of the recording switch means; A color video camera, comprising: control means for controlling recording to start after the white balance adjustment is completed.