JPH05344382A - Luminance correcting circuit for television receiver - Google Patents

Abstract

PURPOSE:To accurately correct the uneven luminance of the entire screen by easily adjusting the amplitude of a luminance signal at an arbitrary point on the screen of a cathode ray tube to the optimum value. CONSTITUTION:An input luminance signal Y and a full-white signal Saw from a full- white signal generation circuit 1 are selected by a changeover switch 12. An addition circuit 2 adds a correction waveform signal Scw from an arbitrary waveform generation circuit 4 to the output signal of the changeover switch 12 and supplies it to a signal amplifier circuit 3. At the time of adjustment, the changeover switch 12 selects the full-white signal Saw to display the full-white image on the screen of the cathode ray tube. In this state, the amplitude of the correction waveform signal Scw is adjusted while successively directing the adjustment point so as to make the luminance of the entire screen coincide with the luminance of the center of the screen. At the time of receiving images, the input luminance signal Y is selected by the changeover switch 12 and the image by the luminance signal Y is displayed on the screen of the cathode ray tube. In this case, as the correction waveform signal Scw which is formed at the time of adjustment is added to the luminance signal Y, the uneven luminance of the entire screen can be accurately corrected, providing the picture without uneven brightness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brightness correction circuit for a television receiver.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing a configuration of a brightness correction circuit of a conventional television receiver. In the figure, the input luminance signal Y is supplied to the adder circuit 2. Also,
The square wave signal Ssq having the horizontal and vertical periods is supplied to the integrating circuit 10, and the parabolic wave signal Spr output from the integrating circuit 10 is supplied to the adding circuit 2.

In the adder circuit 2, the parabolic wave signal Spr is added to the luminance signal Y. The output signal Sad of the adding circuit 2 is supplied to the signal amplifying circuit 3 and converted into three primary color signals of red, green and blue, and these three primary color signals are supplied to the cathode of the electron gun 7 of the cathode ray tube (CRT).

In the example of FIG. 2, the output signal Sad of the adder circuit 2 is a signal in which the amplitude of the luminance signal Y corresponding to the periphery of the screen of the cathode ray tube is raised. Therefore, the brightness around the screen of the cathode ray tube is increased.

[0005]

Since the brightness correction circuit of the conventional television receiver is constructed as described above, there are the following problems. That is, since the parabolic wave signal Spr is formed by integrating the square wave signal Ssq and the parabolic wave signal Spr is added to the input brightness signal Y, the brightness around the screen is increased.
In order to obtain the optimum correction waveform, the constant of the integrating circuit must be set to the optimum value, and it was very difficult to set this constant. Further, since the correction waveform is limited to the parabolic wave, there is a problem that an appropriate correction waveform for adjusting the brightness at an arbitrary point on the screen cannot be obtained.

The present invention has been made to solve the above problems, and the amplitude of the luminance signal at any point on the screen of the cathode ray tube can be easily adjusted to an optimum value to obtain the luminance of the entire screen. It is an object of the present invention to provide a luminance correction circuit for a television receiver that can accurately correct unevenness.

[0007]

A brightness correction circuit for a television receiver according to the present invention includes an all-white signal generation circuit for generating an all-white signal, an arbitrary waveform generation circuit for generating a corrected waveform signal, and an all-white signal generation circuit. A changeover switch for selecting either the all-white signal output from the signal generation circuit or the input luminance signal, and an addition circuit for adding the correction waveform signal output from the arbitrary waveform generation circuit to the output signal of this changeover switch. It is a thing. Then, at the time of adjustment, the all-white signal is selected by the changeover switch to adjust the amplitude of the correction waveform signal output from the arbitrary waveform generating circuit, and at the time of image reception, the input luminance signal is selected by the changeover switch.

[0008]

In the present invention, since the image by the all-white signal output from the all-white signal generating circuit is displayed on the screen of the cathode ray tube during the adjustment, the arbitrary waveform generating circuit is used to keep the brightness of the entire screen constant. The amplitude of the output correction waveform signal can be easily adjusted. Then, at the time of image reception, by adding the correction waveform signal output from the arbitrary waveform generation circuit to the input luminance signal, it is possible to accurately correct the luminance unevenness of the entire screen of the cathode ray tube.

[0009]

EXAMPLES Example 1. FIG. 1 is a block diagram showing an embodiment of a brightness correction circuit according to the present invention. In FIG.
The parts corresponding to those in FIG. 2 are designated by the same reference numerals, and detailed description thereof will be omitted. In the figure, the input luminance signal Y is supplied to the fixed terminal on the a side of the changeover switch 12. An all-white signal Saw is supplied from the all-white signal generating circuit 1 to the fixed terminal on the b side of the changeover switch 12. The changeover switch 12 is connected to the b side during adjustment and is connected to the a side during image reception.

The output signal of the changeover switch 12 is added to the adder circuit 2
Supply to. The correction waveform signal Scw is supplied from the arbitrary waveform generating circuit 4 to the adding circuit 2. The adder circuit 2 adds the correction waveform signal Scw to the output signal of the changeover switch 12.
Then, the output signal Sad of the adding circuit 2 is supplied to the signal amplifying circuit 3 to be converted into the three primary color signals of red, green and blue.
The primary color signal is supplied to the cathode of the electron gun 7 of the cathode ray tube (CRT).

Although not shown, the arbitrary waveform generating circuit 4 is provided with an adjustment point designating means and a correction waveform adjusting means, and at the time of adjustment, the correction waveform is adjusted using these means. At the time of adjustment, the adjustment point display signal Sid is output at a timing corresponding to the adjustment point position on the screen instructed by the adjustment point instruction means from the arbitrary waveform generation circuit 4, and the adjustment point display signal Sid is amplified. Supply to the circuit 3. This adjustment point display signal Sid displays an arrow or the like indicating the position of the adjustment point on the screen.

Next, the operation will be described. When adjusting
Since the changeover switch 12 is connected to the b side and the all-white signal Saw output from the all-white signal generation circuit 1 is supplied to the signal amplification circuit 3 via the addition circuit 2, the all-white signal Saw is displayed on the screen of the cathode ray tube. The image is displayed. In this state, the brightness of the entire screen is adjusted to match the brightness at the center of the screen.
That is, the adjustment point instructing means of the arbitrary waveform generation circuit 4 sequentially indicates the points (adjustment points) on the screen where the brightness should be adjusted (at this time, the arbitrary waveform generation circuit 4 sends the adjustment point display signal Sid to the signal amplification circuit 3). Is supplied, the adjustment point position is displayed on the screen), and each time the correction waveform adjusting means adjusts the amplitude of the portion of the correction waveform signal Scw corresponding to the adjustment point to adjust the brightness of the adjustment point position to the center of the screen. Try to match the brightness. Thereby, the correction waveform signal Scw can be formed.

At the time of image reception, the changeover switch 12 is connected to the side a and the input luminance signal Y is supplied to the signal amplifying circuit 3 via the adding circuit 2. Therefore, an image based on the luminance signal Y is displayed on the screen of the cathode ray tube. It will be displayed. In this case, in the adding circuit 2, since the correction waveform signal Scw formed by the arbitrary waveform generating circuit 4 is added to the luminance signal Y at the time of adjustment as described above, the luminance unevenness of the entire screen of the cathode ray tube is accurately corrected. , An image without uneven brightness is displayed.

[0014]

As described above, according to the present invention, the all-white signal generating circuit for generating the all-white signal, the arbitrary waveform generating circuit for generating the correction waveform signal, and the all-white signal generating circuit are output. Equipped with a selector switch that selects either the all-white signal or the input luminance signal, and an adder circuit that adds the correction waveform signal output from the arbitrary waveform generation circuit to the output signal of this selector switch. The white signal is selected to adjust the amplitude of the correction waveform signal output from the arbitrary waveform generating circuit, and the input luminance signal is selected by the changeover switch when an image is received. Therefore, during adjustment, the image of the all-white signal output from the all-white signal generation circuit is displayed on the screen of the cathode ray tube, and the amplitude of the correction waveform signal output from the arbitrary waveform generation circuit is adjusted so that the brightness of the entire screen becomes constant. The correction waveform signal output from the arbitrary waveform generation circuit is added to the input luminance signal at the time of image reception, so that the luminance unevenness of the entire screen of the cathode ray tube can be accurately corrected, and the luminance unevenness on the screen of the cathode ray tube can be accurately adjusted. There is an effect that an image can be displayed without any.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a brightness correction circuit of a television receiver according to the present invention.

FIG. 2 is a block diagram showing a configuration of a brightness correction circuit of a conventional television receiver.

[Explanation of symbols]

 1 All-white signal generation circuit 2 Addition circuit 3 Signal amplification circuit 4 Arbitrary waveform generation circuit 7 Electron gun of cathode ray tube 12 Changeover switch

Claims (1)

[Claims] 1. An all-white signal generation circuit for generating an all-white signal, an arbitrary waveform generation circuit for generating a correction waveform signal, and an all-white signal output from the all-white signal generation circuit or an input luminance signal. And an adder circuit for adding the correction waveform signal output from the arbitrary waveform generating circuit to the output signal of the changeover switch. During adjustment, the all-white signal is selected by the changeover switch to select A brightness correction circuit for a television receiver, characterized in that the amplitude of a correction waveform signal output from an arbitrary waveform generation circuit is adjusted, and at the time of image reception, the input brightness signal is selected by the changeover switch.