JPS58131881A - Color temperature compensating system for color camera - Google Patents

Abstract

PURPOSE:To designate a sure preset value with a simple constitution, by using a digital switch operated from the side of a camera main body, and controlling a preset value of a counter. CONSTITUTION:When an ''H'' signal is applied to a preset control terminal PS of a preset counter 19, the preset mode is obtained. The counter 19 fetches and holds the output of digital switches 21a-21d provided at a preset value generating section 21 as each bit signal at input terminals S1-S4. Thus, the amplification factor is changed in response to the set output of each bit with the switches 21a-21d, and the system is suitable of preset of color temperature compensation at the standard mode.

Description

[Detailed Description of the Invention] The present invention relates to a color temperature correction circuit for a color camera, and in particular, by digitally presetting the color temperature in the standard mode, variable settings can be made in bit units. It is something.

A commonly used color camera is configured, for example, as shown in Fig. 1, in which light from a subject is focused through a lens system 1 onto a photoelectric conversion surface 2 of an image pickup tube or image pickup plate, and is converted into an electrical signal. is converted to The electrical signals extracted at the photoelectric conversion surface 2 in this way are converted into first to third color lights such as green (G), red ()0, and blue (Bl) in the color separation section 3. The edge is separated into three color signals corresponding to A Y signal as a luminance signal is generated by combining in circuit 1, and a color difference signal B- is generated by combining the Y signal and other two color signals B and R in combining circuit 8. The color difference signals B-Y and PL-Y thus generated are
is modulated by the color carrier signal supplied from the drive signal generation circuit 10 in the process circuit 9 and is supplied to the mixing amplifier 11 as a carrier color signal. The mixing amplifier 11 inputs a luminance signal and a carrier color signal, and
By inputting the synchronization signal, color noise signal, and other various pulse signals supplied from the drive signal generation circuit 10 and performing a mixing process, the NT is output from the output terminal 12.
It generates color television signals based on the $80 standard.

Here, the color camera is provided with a color temperature correction function in case the color temperature of the subject changes.

When correcting this color temperature, there are two methods: one is to use a filter to correct the color temperature of the incident light, and the other is to electrically control the color signals. A configuration is generally used in which the amplification degree of amplifiers 4 to 6 that independently amplify each of the signals is varied. When correcting this color temperature, the amplification degree of the amplifier 4 in charge of the reference color signal (generally green) is fixed, and the amplification degree of the amplifiers 5 and 6 in charge of the other two colors is varied. A method is being taken to do so.

Fig. 2 shows the side surface of a commonly used color camera on which the color temperature adjustment mechanism is installed.A filter is installed on the front side of the color camera body 13 depending on where it is used, whether it is inside the room or outside. The configuration includes a switching knob 14 and serums 15 and 16 that control the amplification degree of the amplifiers 5 and 6.

However, since the color temperature correction with the above configuration is analog controlled, it is difficult to preset the standard state with high precision, and if this is attempted, it would be extremely expensive.

Therefore, an object of the present invention is to provide a color temperature correction method for a color camera that allows easy presetting of color temperature in standard mode.

In order to achieve such an object, the present invention provides a digital switch 3 that allows the amplification degree of each amplifier to be controlled by the output of an up/down counter, and allows the preset value of this up/down counter to be operated from outside the camera body. − is specified in bit units. Hereinafter, a color temperature correction method for a color camera according to the present invention will be described in detail with reference to the drawings.

FIG. 3 is a circuit diagram showing an embodiment of the color temperature correction method for a color camera according to the present invention, and the same parts as in FIG. 1 are indicated using the same symbols.

In the figure, reference numeral 17 compares the amplified first fish signal G and the amplified second electric signal R in the automatic mode, and determines the deviation of the second electric signal R with respect to the first fish signal G. a comparator circuit that generates an up-down control signal A corresponding to the direction and a gate control signal B that controls the gate circuit 18 to close until the first and second electric signals G and R match;
9 is an up-down control signal which sequentially counts the clock pulses OP supplied through the gate circuit 18 when the up-down mode is switched by the user, and a %H' signal is supplied to the preset control terminal PS through the switch 20. Then, a preset counter 21 presets the signals supplied to the input terminals 81 to S4, and 21 is a preset 4-value generating section, which is constituted by four digital switches 21a to 21d provided for each bit. 228 to 22d are resistors connected in series between the input and output of the amplifier 5 for amplifying the color signal, and each of the resistors 228 to 22d
d are R, 2R, and 4R, respectively.

It has a resistance value of 8R and constitutes a feedback circuit.

23 is an analog switch circuit, each resistor 22a~
22d, and are closed by signals output from respective bit output terminals Q1 to Q4 of the preset counter 19.
It has d. In addition, 24 is the input terminal of the fish signal unit, 25
is an input resistance, and 26 is an output terminal.

In the circuit configured as described above, when the level of the second electric signal R supplied to the comparator circuit 17 becomes higher than the level of the first fish signal G in the automatic mode, the comparator circuit 17 outputs the up control signal A. is generated to set the preset counter 19 to the up mode, and a gate control signal B is generated to close the gate circuit 18. As a result, since the clock pulse OP is supplied as a clock signal to the preset counter 19 via the gate circuit 18, the preset counter 19 sequentially counts the clock pulse CP and the count output increases. When the count output increases, the upper portions of the analog switches 23a to 23d provided in the analog switch section 23 are turned on, and accordingly, the negative feedback resistance value decreases and the amplification degree is lowered. When the degree of amplification is lowered, the level of the second electric signal R input to the comparator circuit 17 is sequentially lowered, and when the first and second color signals G and R match, the up control signal is Then, the gate control signal B is cut off and the preset counter 19 is fixed. Also,
When the level of the second electric signal R is smaller than the level of the first electric signal G, the comparator circuit 17 generates a down control signal A, and the preset counter 19 is set to the down mode, and the gate control signal B is generated and the gate circuit 18 is closed. As a result, the preset counter 19 is counted down every time the clock pulse OP is supplied, and its output is sequentially decreased.
~23d is closed. Therefore, since the negative feedback resistance value is gradually decreased, the amplification degree is increased and the level of the second color multiplier R is increased. When the levels of the first and second color signals G and R match, the down control signal A and the gate control signal B are cut off, the count value of the preset counter 19 is fixed, and the color temperature remains in a dull state. do.

Next, when the switch 20 is closed, the preset counter 1
The %H' signal is supplied to the preset control terminal PS of No. 9 to enter the preset mode. In this way, when the preset mode is entered, the preset counter 19 is activated by the digital switches 21a to 21 provided in the preset value generating section 21.
The output of d is taken in and held as each bit signal at input terminals 5i-s4. Therefore, in this preset mode, the amplification degree changes in accordance with the set output of each bit from the digital switches 21a to 21d, and accordingly, the color temperature correction in the standard mode changes. This makes it suitable as a preset. In this case, the negative feedback resistors 22a to 22d, which are short-circuited by the analog switches 23a to 23d controlled by the 4-bit output, have values of 1.2 and 4.
．． Since each is set to 8 times, the overall
The amplification level can be changed to six different types, which is considered to be sufficient for color correction for color cameras.

FIG. 4 shows an example of a color temperature adjustment panel provided on the side of a color camera to which the circuit shown in FIG. Sets can be switched. When the knob 22 is moved to the set position, the auto-white circuit is activated, and when the knob is released, the automatic position is restored. Therefore, the set position is 8- where the auto white circuit is activated. Next, when the knob 22 is set to the standard position, the switch 20 shown in FIG. 3 is closed and the preset counter 19 enters the preset mode. Therefore, in this state, the color temperature is corrected in accordance with the preset value set by the preset value generating section 21. Note that 23 is a preset value generating section for the third electric signal B. In such a configuration, by moving each knob 24, 25 of the preset value generating section 21, 23 according to the marker 26 when in the standard mode 1, the factory default mode is set, and the knob 24
．． By moving 25, you can set a preset value that suits you.

In the above embodiment, a slide type digital switch was used to specify the preset value, but a rotary code switch may also be used. In this case, the color temperature adjustment panel part is as shown in Figure 5. become.

As explained above, the color temperature correction method for a color camera according to the present invention is applicable to a color camera having a color temperature correction circuit that digitally controls the amplification degree of an amplifier that amplifies each color signal using the output of an up/down counter. By controlling the preset value of the counter using a digital switch operated from the side of the main body,
This is used to set a preset value for color temperature correction in standard mode. Therefore, although it has a simple configuration, it is possible to specify preset values reliably, and it has various excellent effects such as being able to incorporate external design by digitalization, which has become mainstream in recent years.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing an example of a conventional color camera.
2 is a side view of the color camera shown in FIG. 1, FIG. 3 is a circuit diagram showing an embodiment of the color camera according to the present invention, and FIGS. 4 and 5 are diagrams of the color temperature adjustment panel. It is a front view showing an example. 5...Amplifier, 17...Comparison circuit, 1
8...Gate circuit, 19...Preset counter, 20...Switch, 21...
...Preset value generation section, 23...Analog switch circuit. Agent Patent attorney Akira Suzuki U.S. - Engraving of drawings (no change in content) Procedural amendment (method) % formula % 1. Indication of case 1982 patent Compilation No. 18548 2. Title of invention Color Camera color temperature correction method 3,
Relationship with the case of the person making the amendment Patent applicant Address Name: Nippon Electric Co., Ltd. 4, Agent 8, Contents of the amendment Application form and engraving of Figure 2.4.5 (no change in content).

Claims (1)

[Claims] (1) Compare the signal levels of the first color light and the 20th color light, and the 10th color light and the third color light, and compare the signal levels of the 1st color light and the 20th color light and the 2nd color light or In a color camera that digitally controls the amplification degree of an amplifier that amplifies a third color light signal, a preset value of the amplification degree for the amplifier is varied in pit units by a digital switch operated from the outer periphery of the camera body. A color temperature correction method for color cameras featuring: