JPH04257194A - Color temperature adjusting circuit of display device - Google Patents

Abstract

PURPOSE:To automatically adjust the color temperature of a display by controlling a level varying circuit which varies the levels of respective color signals of red, blue, and green independently of one another according to the output of optical sensors. CONSTITUTION:The outputs of the two optical sensors S1 and S2 are inputted to a control circuit 8, which decides the color temperature of circumferential light. Then the circuit 8 outputs a control signal corresponding to the color temperature to phase shifting circuits 6 and 7 and level varying circuits 9 and 13. The circuits 9 and 13 can vary the levels of the respective color signals of red, blue, and green independently of one another and the Y signal from a Y signal processing circuit 2 is inputted to regenerating circuits 10, 11, and 12 for the color signals. The respective color signals are generated with color difference signals and Y signal and outputted through the amplifiers 13a, 13b, and 13c of the circuits 10, 11, and 12. Those amplifiers 13a-13c form a circuit 13, which has its gain ratio adjusted independently according to the outputs of the optical sensors S1 and S2 which detect the light temperature of the circumferential light. The levels of the signals are adjusted and the signals arm displayed with the best color temperature for the color temperature of the circumferential light.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color temperature adjustment circuit for a display device that adjusts the color temperature of a display.

0002

2. Description of the Related Art The color reproducibility of a display device varies depending on the temperature of the ambient light of the viewer. White, which forms the basis of color reproducibility, appears undesirable white when the color temperature is lower than the ambient light.
On the other hand, if it is too high, the color will appear bluish. 3 for incandescent light
Approximately 500°K, 65 under white fluorescent light or daytime sunlight
00°K, and about 9000°K for daylight color fluorescent lamps, and color reproducibility is considerably affected by ambient light. Therefore, conventionally, a display device is provided with a color temperature changeover switch, and a desired color temperature is obtained by operating this switch in accordance with the ambient light situation.

0003

However, the conventional configuration has the drawback that the viewer must operate the color temperature changeover switch depending on the ambient light, which is cumbersome to operate. Furthermore, not all viewers are aware of the existence of the color temperature changeover switch and the purpose of its operation.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a color temperature adjustment circuit for a display device that automatically adjusts the color temperature of the display according to the color temperature of ambient light.

[0005]

[Means for Solving the Problems] A color temperature adjustment circuit for a display device according to the present invention for achieving the above problems includes:
an optical sensor that detects the light temperature around the viewer; a level variable circuit that can independently vary the level of each color signal of red, blue, and green; and a level variable circuit that controls the level variable circuit based on the output of the optical sensor. It is equipped with a control circuit.

[0006]

[Operation] The light sensor detects the color temperature of the ambient light, and the control circuit controls the level variable circuit based on the detection output of this light sensor to individually change the level ratio of each color signal, automatically changing the color of the display. The temperature is regulated.

[0007]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a partial circuit block diagram of a display device to which the present invention is applied. In FIG. 1, a video signal led from an input terminal t is input to a bandpass filter 1 and a Y signal processing circuit 2, respectively. The bandpass filter 1 passes only the band of the color difference signal, and the output of this bandpass filter 1 is sent to the R-Y demodulator 3, B-Y
The signals are respectively led to a demodulator 4 and a color synchronization detection circuit 5.

A color synchronization detection circuit 5 detects a color burst signal, which is led to two phase shift circuits 6 and 7, respectively. Each phase shift circuit 6, 7 is R
A demodulation axis command signal, an amplitude command signal, etc. are output to the -Y demodulator 3 and the BY demodulator 4 based on the control signal of the control circuit 8, respectively.

The R-Y demodulator 3 and the B-Y demodulator 4 convert the R-Y signal and the B-
Demodulate the Y signal. The output of the R-Y demodulator 3 is the amplifier 9a.
via the R signal reproducing circuit 10 and directly to the G signal reproducing circuit 11. The output of the BY demodulator 4 is led to a G signal reproducing circuit 11 and a B signal reproducing circuit 12 via respective amplifiers 9b and 9c. This 3
A first level variable circuit 9 is composed of three amplifiers 9a, 9b, and 9c, and this first level variable circuit 9 is connected to a control circuit 8.
Each amplifier 9a, 9b, 9c
The gain ratios of are adjusted independently.

R signal, G signal and B signal reproducing circuit 10,
The Y signal from the Y signal processing circuit 2 is input to 11 and 12, respectively, and the R signal, G signal and B signal reproducing circuit 10,
11 and 12 create each color signal from the color difference signal and the Y signal. R signal, G signal and B signal regeneration circuits 10, 11, 12
The red, green and blue signals of the amplifiers 13a, 13b,
13c. These three amplifiers 13a,
13b and 13c constitute a second level variable circuit 13, and similarly to the first level variable circuit 9, this second level variable circuit 13 controls each amplifier 13a, 13b based on the gain control signal of the control circuit 8. , 13c are independently adjusted.

[0011] Two optical sensors S1 and S2 are attached, for example, to the front surface of the display, and one is configured to detect blue light and the other is configured to detect red light. The outputs of the two optical sensors S1 and S2 are led to a control circuit 8. The control circuit 8 compares the output levels of the two optical sensors S1 and S2 with their respective reference levels, thereby adjusting the color temperature of the viewer's ambient light to approximately 3500°K (incandescent lamp).
, approximately 6500°K (white fluorescent lamp), or approximately 9300°K (daylight fluorescent lamp). Then, a control signal is outputted as described above in accordance with the determination result of these three stages. Since viewers tend to prefer a white temperature that is about 3000°K higher than the ambient light, it is preferable to output a control signal taking this into account.

In the above configuration, two optical sensors S1,
The output of S2 is input to the control circuit 8, and the control circuit 8 determines the color temperature of the ambient light of the viewer. The control circuit 8 outputs a control signal corresponding to the determined color temperature to the phase shift circuits 6 and 7, the first variable level circuit 9, and the second variable level circuit 13.

The R-Y demodulator 3 and the B-Y demodulator 4 demodulate the color difference signals based on the demodulation axis, vibration, etc. based on command signals from the phase shift circuits 6 and 7, respectively. Therefore, even if the color temperature on the transmitting side and the color temperature on the receiving side are different, proper color reproduction can be achieved.

Further, each amplifier 9a, 9b, 9c, 13 of the first level variable circuit 9 and the second level variable circuit 13
The gains of a, 13b, and 13c are controlled based on the control signal, and the level of each color signal is adjusted to display the display at the optimal color temperature relative to the color temperature of the ambient light.

In this embodiment, the two optical sensors S1 and S2 are used to determine the color temperature of the ambient light in three stages, but the color temperature may also be determined in two stages. Color reproducibility can be further improved by using an optical sensor that outputs a proportional output to enable even more detailed discrimination, and by controlling accordingly.

Furthermore, in this embodiment, the level variable circuit is composed of two, the first level variable circuit 9 and the second level variable circuit 13, but either one may be used.

[0017]

As described above, according to the present invention, there is provided a light sensor that detects the color temperature of ambient light, a level variable circuit that independently varies the level of each color signal, and a light sensor that detects the color temperature of ambient light. Since the level variable circuit is controlled, it is possible to automatically achieve optimal color reproducibility for the color temperature of ambient light.

[Brief explanation of the drawing]

FIG. 1 is a partial circuit block diagram (embodiment) of a display device.

[Explanation of symbols]

S1, S2...light sensor 8...Control circuit 9...First level variable circuit 13...Second level variable circuit

Claims (1)

[Claims] 1. A light sensor that detects the light temperature around a viewer; a level variable circuit that can independently vary the level of each color signal of red, blue, and green; A color temperature adjustment circuit for a display device, comprising: a control circuit for controlling a variable circuit.