JP2000316173A - White balance adjusting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a white balance which can be made uniform from low luminance to high luminance without fluctuation by controlling a blue and a green gamma correcting circuits through a bus line from a white balance adjuster and automatically preparing a necessary correction curve. SOLUTION: A television receiver equipped with a gamma correcting circuit 2, a gamma starting point DAC 3, a gamma ending point DAC 4, and a gain controller DAC 5 is connected through a bus line with a white balance adjuster 8 in this white balance adjusting device. In this case, a white balance which is uniform from low luminance to high luminance can be realized by absorbing the dispersion in a CRT or the dispersion of a white balance in the case the gamma correcting circuit is fixed. Moreover, the white balance adjuster is connected through the bus line with the television receiver main body, and gamma correction data are automatically prepared so that an adjusting time can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit and an adjuster for controlling a green, blue and red video output from a white balance adjuster in a television receiver and automatically adjusting the white balance. .

[0002]

2. Description of the Related Art Conventionally, green and blue phosphor gamma corrections for television receivers are either fixed or one-point or two-point correction, and are fixed at a value aimed at the center of variation between sets.

[0003]

However, in general, a uniform white balance cannot be obtained with the above circuit configuration. In particular, it is difficult to realize a uniform white balance from low luminance to high luminance with only two-point correction due to the gamma characteristics of blue and green in a projection type television. It takes time to design to match the luminance characteristics. Further, the gamma correction is fixed, and the variation cannot be absorbed.

[0004] Accordingly, the present invention provides a CRT having any characteristics.
In order to be able to cope with the problem, an arbitrary number of gamma correction circuits are provided, and further, the gamma circuit is controlled by the white balance adjuster and the necessary gamma correction circuit is automatically created.

[0005]

Means for Solving the Problems In order to achieve the above object, a means of the present invention is to provide a gamma correction circuit 2 having an arbitrary number of breakpoints and gains from a white balance adjuster 8 side. A means for controlling the correction DAC 3 through the bus line and automatically controlling the gamma correction circuit is provided.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1 of the present invention uses a white balance adjuster calibrated to a preset white balance value from green, blue, and red drive-brightness characteristics, In a television receiver for controlling a drive ratio of green, blue, and red to a target white balance value, an arbitrary white balance adjuster is provided in the television receiver to adjust the target white balance value with the white balance adjuster. A blue gamma correction circuit capable of controlling a break point and an arbitrary gain is provided, and the white balance adjuster automatically calculates a necessary correction value from a measurement result of green and blue, and the white gamma correction circuit sets the white gamma correction circuit to the white balance. The adjuster automatically controls the target white balance automatically.

According to a second aspect of the present invention, in the gamma correction circuit of the first aspect, gamma correction is applied to green instead of blue gamma.

Hereinafter, a white balance adjusting device according to an embodiment of the present invention will be described with reference to FIG.

(Embodiment 1) FIG. 1 is a block diagram of a white balance adjusting apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a clamp circuit, 2 denotes a gamma correction circuit, 3 denotes a DAC for a gamma start point, 4 denotes a DAC for a gamma end point, 5 denotes a DAC for a gain control, and 6 denotes a DAC for a gain control.
Denotes a video output amplifier, 7 denotes a detector for white balance adjustment, and 8 denotes a white balance adjuster body. The portion (green gamma circuit) enclosed by the broken line is not included in the first embodiment.
Next, the operation of the above configuration circuit will be described.

First, the gamma correction circuit 2 is turned off, and no correction is performed on the input signal. In this state, a white signal is input, and the ratio of blue to green is read by the white balance adjuster. If the white balance is equal to the target value, the ratio is 100%. If there is a deviation, the ratio between green and blue changes according to the deviation amount.

If this deviation is read by a white balance adjuster for every luminance from low luminance to high luminance, a blue correction curve for green is calculated. This data is transferred to the gamma start point DAC of 3 and the gamma end point D of 4 through the bus line.
The data is transferred to the AC, 5 gain control DAC, and the necessary gamma correction curve is automatically created and automatically repeated until the target white balance value is reached.

(Embodiment 2) FIG. 1 is a diagram in which a broken line portion (green gamma correction circuit) is added to show another white balance adjusting device according to an embodiment of the present invention. The circuit configuration shown in FIG. 1 is obtained by adding a green gamma correction circuit to the first embodiment, and can simplify complicated blue gamma correction.

[0013]

As is apparent from the above description, the white balance adjusting apparatus of the present invention absorbs the variation of the CRT and the variation of the white balance when the gamma correction circuit is fixed, and achieves uniform brightness from low luminance to high luminance. White balance can be achieved. In addition, by connecting the white balance adjuster and the television receiver body via a bus line and automatically generating gamma correction data, the adjustment time can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a white balance adjustment device of the present invention.

FIG. 2 is a characteristic diagram according to an embodiment of the white balance adjustment device of the present invention.

[Explanation of symbols]

 Reference Signs List 1 clamp circuit 2 gamma correction circuit 3 gamma start point DAC 4 gamma end point DAC 5 gamma gain control DAC 6 video output amplifier 7 white balance detector 8 white balance adjuster 9 green gamma correction DAC

Claims (2)

[Claims] 1. Using a white balance adjuster calibrated from a drive characteristic of green, blue, and red to a white balance value set in advance to control a drive ratio of green, blue, and red to a target value. In a television receiver that adjusts to a white balance value, a blue gamma correction circuit that can control an arbitrary break point and an arbitrary gain in the television receiver in order to adjust to a target white balance value with the white balance adjuster. The white balance adjuster automatically calculates a necessary correction value from the measurement results of green and blue, the white balance adjuster automatically controls the blue gamma correction circuit, and adjusts a target white balance. A white balance adjustment device characterized by automatic adjustment. 2. A green gamma correction circuit capable of controlling an arbitrary break point and an arbitrary gain is provided, and a white balance adjuster automatically calculates a necessary correction value from green and red measurement results.
2. The white balance adjusting device according to claim 1, wherein the white balance adjuster automatically controls the green gamma correction circuit to automatically adjust a target white balance.