JPS59144292A - Color video camera - Google Patents

Abstract

PURPOSE:To facilitate color temperature correction and to simplify circuit constitution by controlling a color temperature conversion according to color temperature information so that the filter is put on and off an optical path automatically. CONSTITUTION:When the color temperature conversion filter 24 is off the photographic optical path, a filter detecting circuit 25 detects that to switch the control voltages VR and VB of a white balance adjusting circuit 20 to the voltage which varys as shown by characteristics P, and sets the detected temperature of a color temperature detecting circuit 21 to specific temperature. Therefore, when the color temperature of object light rises above the specific temperature, the detecting circuit 21 generates an output, and when an L-level vertical blanking signal is generated, a timing setting circuit 22 sends an output to a filter control circuit 23 to put the color temperature conversion filter on the optical path. When the filter 24 is put on the optical path, the control voltages VR and VB are switched to the voltage which varys as shown by a characteristic curve Q, switching the detected temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color video camera, and more particularly, to a color video camera having automatic white balance control means for automatically performing color temperature correction.

As shown in FIG. 1, the basic configuration of a conventional Cassie video camera is to form an image of a subject transmitted through an optical lens 1 on an image sensor 2, and to convert a signal photoelectrically by the image sensor 2. The R, G, B signal processing circuit 3 separates the signal into three primary color signals of R (red), G (G), and B (blue) to obtain an NTSC video signal. By the way, when photographing under a light source with a high color temperature, the dynamic range of the image sensor 2 will be exceeded and good color balance will be lost. In order to lower the color temperature, a color temperature conversion filter 4 called a so-called A type filter is inserted between the optical lens 1 and the image sensor 2 from ζ to the beak. However, when inserting this color temperature conversion filter 4 into the photographing optical path, conventional color video cameras only have a switching display such as indoor ← outdoor or lamp shaft @, and the user has to select the There is an inconvenience in that the above switching has to be performed by determining whether the color temperature of the light source is high or low.

In view of the above points, an object of the present invention is to automatically perform color temperature correction using an auto-white I (color temperature information is obtained from a lance control means, and a color temperature conversion filter is automatically moved forward and backward into the photographing optical path. The main advantage is to provide controllable video cameras.

Hereinafter, the present invention will be explained with reference to illustrated embodiments.

FIG. 2 is a block diagram of a color video camera showing one embodiment of the present invention. The object light image transmitted through the photographing optical lens 11 of the color video camera 2 is focused on the image sensor 12, and from the image sensor 12, RlG, B 3Jfj, color photoelectric conversion signals f'iR signal amplifier 13, G signal amplifier 1
4. The B signal amplifier 15 separates and amplifies the signals. Among these amplifiers 16 to 15, the gains of the R signal amplifier 16 and the B signal amplifier 15 are different from those of the auto white balance control circuit 1.
It is controlled by a white balance adjustment circuit 20 of No. 6. The auto white balance control circuit 16 is
An R-B detector 18 consisting of a light-receiving element having a color filter equal to the original characteristic of the image sensor 120 is provided with a force tK that is large enough to receive light from a subject of a video camera, In front of the detector 18 is a milky white diffuser plate 1.
7 has been plated. This milky-white diffuser plate 17 diffuses the reflected light from the subject, adds color, and integrates the light, based on the idea that adding color to the various colored lights of everyday scenes will bring the light as close to white as possible. The output R and B signals converted into photocurrents from the R-B detector 18 are led to an arithmetic circuit 19, where they are logarithmically converted and differentially amplified. The output of the white balance adjustment circuit 2o changes only by the change in color temperature of the light source (subject light), regardless of the scene incident on the R-B detector 18, so the white balance adjustment circuit 2o adjusts the white balance to an appropriate white balance. For adjustment, R signal amplifier 13 and B signal amplifier 15
, a control voltage VB for controlling the gain, respectively.
Send VB.

Further, among the control voltages VR and VB output from the white balance adjustment circuit 2o, one control voltage vR is led to the color temperature detection circuit 21. This control voltage vR changes according to the change in the white balance adjustment temperature, as shown in the characteristic kP or Q shown in FIG.
detects a predetermined color temperature when the control voltage VR changes. That is, the color temperature detection circuit 21 has two comparators, and when the control voltage vR increases, it performs the detection operation at a color temperature of 6000 K, and when the control voltage VR decreases, it performs the detection operation at a color temperature of 6000 K. The detection operation is performed at a color temperature of 5000°. The output of the color temperature detection circuit 21 is guided to a timing setting circuit 22. Further, as shown in FIGS. 4(A) and 4(B), the timing setting circuit 22 is adapted to receive a vertical blanking signal which is generated in synchronization with the vertical blanking period of the NTSC video signal. When an output from the color temperature detection circuit 21 is generated, the timing setting circuit 22i1 is synchronized with the vertical blanking signal and sends a signal to the filter control circuit 26. The filter control circuit 23 inserts a color temperature conversion filter 24, which is a so-called A type filter, for converting the color temperature to a lower value, between the optical lens 11 and the S image element 12, that is, into the photographing optical path, or This is for moving the color temperature conversion filter 24 out of the photographing optical path from the photographing optical path, and controls the forward and backward movement of the color temperature conversion filter 24 by the output signal of the timing setting circuit 22. A filter detection circuit 25 detects whether the color temperature conversion filter 24 is present in the photographing optical path or removed from the photographing optical path, and the detection output of the filter detection circuit 25 is used for white balance adjustment. It is designed to be guided to a circuit 20 and a color temperature detection circuit 21. That is, the filter detection circuit 25
sends information on whether or not the color temperature conversion filter 24 is present in the photographing optical path to the white balance adjustment circuit 20;
The characteristics of the control voltages VR and VB are switched depending on whether the color temperature conversion filter 24 is in the photographing optical path or outside the photographing optical path, so that an appropriate white balance can always be obtained. As shown in the sixth graph, when looking at the control voltage V'R, when the color temperature conversion filter 24 is not present in the photographing optical path, the characteristic is 1%lP for good color temperature.
The change shown in is made, and the filter 24 is in the photographing optical path,
If it exists, the control characteristic is switched by the output of the filter detection circuit 25 so as to change as shown by the characteristic line Q. The control voltage VB is basically equivalent to the inverted version of the control voltage VR, and has a characteristic opposite to that shown in FIG. In addition, the filter detection circuit 25
When the detection output of is led to the color temperature detection circuit 21, if the filter 24 is not present in the photographing optical path, the detected color temperature in the color temperature detection circuit 21 becomes 6000',
When the filter 24 is present in the photographing optical path, the detected color temperature is 5000°. The reason why the detected color temperatures are made to differ by five degrees is to determine the control operation of the color temperature conversion filter 24.

In the color video camera configured as above,
Now, assuming that the color temperature conversion filter 24 has moved out of the photographing optical path, the filter detection circuit 25 detects this and adjusts the control voltages VR and VB of the white bar adjustment circuit 200 to the characteristic edge shown in FIG. In addition to switching to a voltage that changes like P, the detected temperature of the color temperature detection circuit 21 is set to 6000.
It is set to °K. Therefore, in this state, if the color temperature of the subject light rises and exceeds 6000°K, the color temperature detection circuit 21 will output an output, and a vertical blanking signal at the ``L'' level will be generated. At this point, the timing setting circuit 22 sends an output to the filter control circuit 23, so that the filter control circuit 26 performs a control operation to move the color temperature conversion filter 24 into the photographing optical path, as shown in FIG. 4(C). Let's do it. Since the entry operation of the color temperature conversion filter 24 is completed while the vertical blanking signal is being issued, the movement of the filter 24 does not affect the image and does not cause color unevenness. When the color temperature conversion filter 24 enters the photographing optical path, the filter detection circuit 25 detects this and switches the control voltages VR and VB of the white balance adjustment circuit 200 to voltages that change as shown in the characteristic line Q shown in FIG. At the same time, the detected temperature of the color temperature detection circuit 21 is switched to 5000K. Therefore, when the color temperature of the subject light becomes higher than 6000°, the characteristic line QK becomes clearer and the control voltage VR
changes, but after the control voltage VR shifts to the voltage of the characteristic line Q, if the color temperature of the subject light becomes lower,
The color temperature detection circuit 21 performs a detection operation at a color temperature of 5000°, and the detection circuit 21 outputs an output.
At this time, in the same way as when inserting the filter 24, '
The filter control circuit 23 is activated by the output from the timing setting circuit 22 which is generated in synchronization with the L'' level vertical blanking signal, and performs a control operation to move the color temperature conversion filter 24 out of the photographing optical path. ,
As shown in FIG. 4(C), the withdrawal operation of the filter 24 is performed from the start to the end within the time period during which the vertical blanking signal is being issued. When the color temperature conversion filter 24 moves out of the photographing optical path, the filter detection circuit 2
5, the white balance vIA adjustment circuit 2o is detected again.
The control voltages VR and vn are changed to voltages that vary as shown in FIG.

In this way, a predetermined color temperature is detected from the output of the auto white balance control circuit 16 and the color temperature conversion filter 2 is applied.
4. Control force 1 for advancing and retreating toward the photographing optical path is performed automatically.

In the above embodiment, the filter detection circuit 25 detects whether or not the color temperature conversion filter 24 is present in the photographing optical path. The voltage is switched and controlled depending on the presence or absence of the filter 24.The filter detection circuit 25 can also be omitted as in the embodiment shown in FIG.

FIG. 5 is a block diagram of a color video camera showing another embodiment of the present invention, in which the filter detection circuit 25 in the embodiment of FIG. 2 is not provided, but an auto white/clearance control circuit is provided. 16 diffuser plate 17 and R-B
A color temperature conversion filter 26 can also be inserted between the detector 18, that is, in the detection optical path. This color temperature conversion filter 26 is controlled by a filter control circuit 26, and the color temperature conversion filter 24
When the light moves forward and backward through the photographing optical path, it also moves forward and backward through the detection optical path.

That is, in the color video camera shown in FIG. 5, when the color temperature conversion filter 24 is present in the photographing optical path as shown in the figure, the color temperature conversion filter 24 is also present in the detection optical path. Therefore, at this time, the control voltages VR and VB of the white balance adjustment circuit 20 become the voltages shown by the characteristic line Q in FIG. The gain of the B signal amplifier 15 is controlled. Then, while the color temperature conversion filters 24 and 26 are still used, when the color temperature becomes low and decreases by 5000°, this is detected by the color temperature detection circuit 21, and the timing is synchronized with the vertical blanking signal. Since the setting circuit 22 operates the filter control circuit 23, the color temperature conversion filter 24 is moved out of the photographing optical path and the color temperature conversion filter 26 is moved out of the detection optical path by the filter control circuit 23. Color temperature conversion filter 24.2
6 moves out of each optical path, the control voltages 'VR, VB of the white balance adjustment circuit 20 become the voltages of the characteristic line P shown in FIG. When the color temperature exceeds 6000°, it is detected by the color temperature detection circuit 21, and the filter control circuit 26 operates in the same manner as described above to cause the color temperature conversion filter 24 to enter the photographing optical path. The color temperature conversion filter 26 is introduced into the detection optical path.

As described above, according to the present invention, the color temperature conversion filter is controlled to move in and out of the photographing optical path from a force outside the photographing optical path into the optical path, or vice versa, based on the color temperature information obtained from the auto white balance control means. Therefore, color temperature correction including control of the color temperature conversion filter can be further automatically performed with a simple circuit configuration, and an easy-to-use color video camera can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a basic block diagram showing an example of a conventional color video camera. FIG. 2 is a block diagram of a color video camera showing one embodiment of the present invention. FIG. 6 is a basic block diagram showing an example of a conventional color video camera. Figure 4 CA) to (C) are time charts for explaining the control movement of the color temperature conversion filter, and Figure 5 is a characteristic diagram of the control voltage VR from the white/ FIG. 3 is a block diagram of a color video camera showing another embodiment of the invention. 16... Auto white balance control circuit (auto white balance control means) 21... Color temperature detection circuit (color temperature detection means) 22.
...Timing setting circuit (timing setting means) 26
...Filter control circuit (filter control means) 2
4...Color temperature conversion filter 25...Filter detection circuit (filter detection means) %2 Figure 16 Procedure amendment (voluntary) 1. Indication of the case: Patent Application No. 19079, filed in 1982, 2, Title of the invention: Color video camera 3, Relationship with the case by the person making the amendment: Address of the patent applicant: 2-43-2 Hatagaya, Shibuya-ku, Tokyo Name (037) Olympus Optical Industry Co., Ltd. 4, Address: 5-52-14-5 Matsubara, Setagaya-ku, Tokyo.
Column 6, Detailed Description of the Invention, Contents of Amendment (1) of the specification to be amended
The "detected color temperature" written in B-iRJ and the "detected color temperature" written in line 11 of the same page are respectively set as "setting values".
Changed to (3) "Filter 24" written in the fourth line of page 12 is corrected to "filter 26."

Claims (4)

[Claims] (1) Auto white balance control means that automatically performs color temperature correction; Color temperature detection means that detects the color temperature from this auto white balance control means; A color video camera comprising: filter control means for advancing and retracting a color temperature conversion filter; (2) A patent characterized in that the filter control means has timing setting means for controlling the forward and backward movement of the color temperature conversion filter from the start to the end within the vertical blanking period. Force 2-video camera according to claim 1. (3) Whether or not there is an auto white balance control means that automatically performs color temperature correction, a color temperature detection means that detects color temperature from this auto white balance control means, and a color temperature conversion filter in the photographing optical path. A color video camera comprising: a filter detecting means for detecting a color temperature converting filter; and a filter controlling means for moving a color temperature conversion filter forward or backward in a photographing optical path by operating according to the output of the filter detecting means and the output of the color temperature detecting means. (4) A patent claim characterized in that the filter control means has a timing setting means for controlling the forward and backward movement of the color temperature conversion filter from the start to the end within a vertical blanking period. A color video camera according to item 3 of the scope.