JPH04243393A - Video control circuit for video display equipment - Google Patents

Abstract

PURPOSE:To adjust a color temperature of a screen to a most suitable temperature even when the state of a surrounding light of a video display device is changed. CONSTITUTION:A semiconductor color sensor 12 detecting a color temperature of an external light is provided to a video display equipment displaying a video image in color onto a display device 7 while controlling a color temperature on the screen, for example, a video control circuit of a color television receiver and a color temperature displayed onto the screen of the display device 7 is changed over and controlled in response to the result of color detection of the color sensor 12. For example, a level of each of R, G, B color signals is switched by a microcomputer or the like and a video image with an optimum color temperature in matching with the color temperature of surrounding light is displayed on the screen of the display device 7. Furthermore, the relation between the color temperature of the external light and the color temperature on the screen of the display device 7 to be set is changed optionally by an external operation means 15.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video control circuit for video display equipment, and more particularly to a control circuit used in color television receivers and the like to display optimal color video.

0002

2. Description of the Related Art FIG. 3 shows a conventional video control circuit for a color television receiver. In the figure, a tuner (1) is equipped with an intermediate frequency amplification circuit (2) and a video amplification circuit (3). A matrix circuit (4) for synthesizing a luminance (Y) signal and a color difference signal is connected through the matrix circuit (4), and a color signal reproducing circuit (4) for forming a color difference signal from the output of the intermediate frequency amplifier circuit (2) is connected to the matrix circuit (4). 5) is connected. The matrix circuit (4) also includes resistors R1,
A video output circuit (6) is connected via R2 and R3, and a display device (7) made of a CRT cathode ray tube or the like is connected to this video output circuit (6). A control section (8) that controls the entire device including channel selection and color temperature control is provided, and the resistors R1, R2, Resistors R4 to R9 and transistors Q1, Q2, Q3 which perform a color temperature switching operation together with R3 are connected, and a color temperature changeover switch (9) is connected to the control section (8).

Next, the operation of the circuit shown in FIG. 3 will be explained. First, the RF signal received from the tuner (1) is converted into a baseband signal through the intermediate frequency amplification circuit (2). Of this baseband signal, the Y signal is sent to the video amplification circuit (3), and the color signal is sent to the video amplification circuit (3). Color signal regeneration circuit (5)
supplied to The Y signal processed by the video amplification circuit (3) and the color difference signal processed by the color signal reproducing circuit (5) are then transferred to the R(
These primary color signals are supplied to the display (7) via the video output circuit (6) through the resistors R1, R2, and R3. be done. Therefore, the display device (7) displays the video in color based on the RGB signals.

[0004] Here, the user presses the color temperature changeover switch (
By toggling 9), the color temperature of the screen display of the display device (7) can be set to any level of high, medium, or low. That is, Table 2 below shows transistors Q1, Q2, Q3 at each level of color temperature.
When setting the color temperature to "high" with the color temperature changeover switch (9), the controller (8) sends H (Hi) to the transistors Q1 and Q2.
) signal is supplied to the transistor Q3, while the L signal is supplied to the transistor Q3.
w) providing a signal;

Then, when the transistors Q1 and Q2 supplied with the H signal become conductive, and the transistor Q1 becomes conductive, the R signal is applied to the resistors R1, R4,
When transistor Q2 is conductive, the G signal is divided by resistor R2 and R8, R9. Therefore, the ratio of the B signal among the R, G, and B signals increases relatively, and the color temperature of the screen display becomes more bluish.

[0006]

[Table 1]

Similarly, when setting the color temperature to "medium" using the color temperature changeover switch (9), the output from the control section (8) controls the ratio of each R, G, and B signal to be constant. The color temperature of the screen display is set to the standard state. Furthermore, the color temperature can be changed using the color temperature changeover switch (9).
When setting it to "low", an H signal is supplied from the control section (8) to transistors Q2 and Q3, while transistor Q1
Since the L signal is supplied to the
As a result, the color temperature of the screen display becomes more reddish.

[0008]

[Problems to be Solved by the Invention] Since the conventional device is configured as described above, adjustment and setting of color temperature requires external operation, and the surrounding light conditions change during viewing. However, there was a problem in that the color temperature of the screen could not be set to the optimal state without the above-mentioned external operation. Also,
As mentioned above, the color temperature setting is limited to several levels, such as "high, medium, and low," and there is also the problem that it is difficult to make fine adjustments.

The present invention has been made to solve the above problems, and its purpose is to automatically adjust the color temperature of the screen to an optimal value even when the ambient light conditions change. The purpose of the present invention is to provide a video control circuit for a video display device that can perform the following functions.

0010

[Means for Solving the Problems] In order to achieve the above object, the invention according to the first claim provides a video display device that performs control for displaying video in color on a display while switching the color temperature on the screen. In the video control circuit, a color temperature detection means for detecting the color temperature of external light is provided, and the color temperature displayed on the screen of the display device is switched and controlled according to the color detection result of the color temperature detection means. It is characterized by

In the above case, the relationship between the color temperature of the external light and the color temperature on the screen of the display device set thereby can be arbitrarily varied by an external operating means.

Preferably, the video display device is a color television receiver, and the color temperature control based on the output of the color temperature detection means is performed by a microcomputer.

[0013]

[Operation] According to the above configuration, when the color temperature of external light around the video display device is detected by the color temperature detection means, the control circuit consisting of, for example, a microcomputer establishes a certain relationship with the detected color temperature. Control is performed to set the color temperature on a certain screen, and a control signal is sent to a circuit that switches the color temperature. Then, the color temperature switching circuit changes the level of each color signal, for example, R, G, and B, and an image with the optimal color temperature that matches the color temperature of the surrounding light is displayed on the display screen. It turns out. Further, according to the second aspect of the invention, the predetermined relationship between the color temperature set on the screen of the display device and the color temperature of external light detected by the color temperature detection means can be changed, and the user You can make your own settings.

[0014]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings. FIG. 1 shows the configuration of a video control circuit of a color television receiver according to an embodiment. In the figure, the tuner (1) is equipped with an intermediate frequency amplification circuit (
2) and the matrix circuit (4) via the video circuit (3)
A color signal reproduction circuit (5) that outputs a color difference signal is connected to this matrix circuit (4), and a display device is connected to the rear stage of the matrix circuit (4) via a video output circuit (6). (7) is connected. Also, as a color temperature switching circuit, resistors R1 to R9 and a transistor Q1
~Q3 are provided between the matrix circuit (4) and the video output circuit (6).

A microcomputer (10) is provided to control the entire device including channel selection and color temperature control, and a color controller for detecting the color temperature of external light around the video display device. A semiconductor color sensor (12) is provided as temperature detection means. This semiconductor color sensor (12) is arranged near the display device (7) at a position where it can satisfactorily detect changes in external light. A/D converter (1
3) is connected to the microcomputer (10). On the other hand, a D/A converter (14) that converts digital control data from the microcomputer (10) into analog control data is connected to the microcomputer (10), and this D/A converter (
Analog control data outputted from 14) is outputted to the base terminals of the transistors Q1 to Q3.

Furthermore, a microcomputer (1
0) is connected to an operating means (15) for externally setting and adjusting the relationship between the color temperature detection data from the A/D converter (13) and the data to the D/A converter (14). As the means (15), a normal volume or a semiconductor sensor such as a phototransistor, or a semiconductor position detection sensor such as a PSD is used, and thereby the color temperature on the screen set according to the color temperature of external light can be changed. .

Next, the operation of color temperature control will be explained. First, color temperature data of external light detected by a semiconductor color sensor (12) is converted from an analog value to a digital value by an A/D converter (13), and then input to a microcomputer (10). In this microcomputer (10), a color temperature value on the screen corresponding to previously detected color temperature data is set by an operating means (15).

[0018]

[Table 2]

Table 2 shows the operating states of transistors Q1 to Q3 for changing the color temperature on the screen, and the data obtained by the A/D converter (13), that is, the color temperature of external light, is shown in Table 2. When the voltage changes from high to medium to low, the microcomputer (10) changes the base voltage of the transistor Q1 to H through the D/A converter (14).
(Hi) state is continuously converted to L (Low) state. In this way, when the base potential of the transistor Q1 decreases, the current flowing through the resistors R7 and R4 also gradually decreases, and the R signal component supplied to the video output circuit (6) through the resistor R1 increases. Therefore, the color temperature of the screen displayed on the display device (7) gradually becomes redder. Similarly, when the base potential of the transistor Q3 increases, the current flowing through the resistors R9 and R6 gradually increases, and the B signal component supplied to the video output circuit (6) through the resistor R3 decreases. Therefore, the color temperature displayed on the screen of the display device (7) gradually loses its bluish tinge.

Furthermore, the base potential of the transistor Q2 is once continuously converted from the H state to the L state, and then continuously changes from the L state to the H state again. In other words, the resistances R8 and R5 decrease once and then increase again, so that
G supplied to the video output circuit (2) through resistor R2
The signal component changes from increasing to decreasing, and the color temperature displayed on the display (7) once increases in greenness and then loses its greenness again. In this way, the semiconductor color sensor (1
When the color temperature detected in step 2) changes, the color temperature on the screen changes accordingly, making it possible to display colors on the screen that correspond to changes in external light.

FIG. 2 shows the relationship between the color temperature of outside light and the color temperature of the screen displayed on the display (7) in the embodiment. In FIG. 150 of
Assuming that the temperature is 0°K, the microcomputer (10) into which data from the A/D converter (13) has been input is connected to the operating means (15).
), the color temperature of the screen displayed on the display (7) of the D/A converter (14) is as shown in Figure (b). , 4500° at point p', which is 3000°K higher than the color temperature of outside light.
Output data so that it can be set to K.

[0022] Also, the external light is at 3500° at point q in figure (a).
If the microcomputer (10) inputs the detection data from the A/D converter (13), the color temperature of the screen displayed on the display (7) of the D/A converter (14) is As shown at point q' in (b), data is output so that the color temperature can be set to 6500°K, which is 3000°K higher than the color temperature of external light.

In this way, in the embodiment, the color temperature on the screen is controlled to be 3000°K higher than the color temperature of outside light, and even if the outside light changes, the color temperature on the screen is automatically adjusted. will be adjusted accordingly.

Note that the above-mentioned color temperature of outside light and display (7)
The predetermined relationship with the color temperature of the screen displayed in ) can be changed by an external operating means (15), allowing a user to make settings with a high degree of freedom according to his or her own preferences.

In the above embodiment, the semiconductor color sensor (1
2) and the color temperature switching circuit that controls the color signal level, an A/D converter (13), a microcomputer (10), and a D
Although the /A converter (14) is provided to perform digital processing, it is also possible to continuously control the color temperature by analog processing without using these circuits.

[0026]

As explained above, according to the inventions of the first and third claims, the color temperature of external light is detected and the color temperature of the screen is automatically controlled based on this detected value. With this new configuration, even if the external light around the video display device changes, it is possible to always display the optimal color on the screen that matches the external light, without having to perform external settings like in the past. It becomes possible.

Further, according to the second aspect of the invention, since the width of the above-mentioned automatic color temperature adjustment can be controlled by external operation, the degree of freedom in automatic color temperature adjustment can be increased. , it is possible to realize color expression that matches the user's senses.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing the configuration of a video control circuit of a video display device according to an embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the color temperature of external light [Figure (a)] and the color temperature of the screen to be adjusted [Figure (b)] in the example.

FIG. 3 is a block circuit diagram showing the configuration of a video display circuit of a conventional video display device.

[Explanation of symbols]

(3) Video amplification circuit (4) Matrix circuit (5) Color signal regeneration circuit (7) Display unit (10) Microcomputer (12) Semiconductor color sensor (13) A/D converter (14) D/A converter (15) Operation means

Claims (3)

[Claims] 1. In a video control circuit of a video display device that performs control to display a video in color on a display while switching the color temperature on the screen, a color temperature detection means for detecting the color temperature of external light is provided, A video control circuit for a video display device, characterized in that the color temperature displayed on the screen of the display device is switched and controlled according to the color detection result of the color temperature detection means. 2. The video image according to claim 1, wherein the relationship between the color temperature of the external light and the color temperature on the screen of the display device set thereby is arbitrarily varied by an external operating means. Video control circuit for display equipment. 3. The video display device according to claim 1, wherein the video display device is a color television receiver, and a microcomputer performs color temperature control based on the output of the color temperature detection means. Video control circuit.