JPH0479480A - Automatic picture quality adjusting circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic video quality adjustment circuit that corrects variations in image quality between channels due to band characteristics of a tuner of a color television receiver.

[Prior Art] Fig. 2 is a video block diagram of a conventional color television receiver.
) is an intermediate frequency amplification circuit, (3) is a video detection circuit, (4)
(5) shows an image quality adjustment circuit, and (5) shows a video amplification circuit.

Next, the operation of the above configuration will be explained based on FIG. 2.

First, use the tuner (1) to select and amplify the desired radio waves from the TV radio waves, and also use the tuner (1) to select and amplify the desired radio waves from the TV radio waves.
5 MHz). Intermediate frequency amplifier circuit (2)
The receiver is responsible for most of the characteristics such as gain, bandwidth, and selectivity required for the receiver. A color television signal is extracted from the intermediate frequency signal detected and amplified by the video detection circuit (3). Subsequently, the image quality adjustment circuit (4) corrects the video signal. Finally, the video amplifier circuit (5) generates a signal to be applied to the picture tube.

[Problem to be solved by the invention]

However, the conventional image quality adjustment circuit described above requires manual adjustment, so when using inexpensive tuners with large variations in band characteristics, adjustment is required for each individual tuner, and There was a problem in that delicate image quality adjustments had to be made between channels as well.

This invention was made to solve the above-mentioned problems, and it is possible to deal with variations in band characteristics when using an inexpensive tuner, and also to automatically adjust the video quality so that there is no need to adjust the image quality when switching channels. The purpose is to provide circuits.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a conventional video processing circuit including a synchronization signal detection circuit for extracting a synchronization signal from a video signal and a circuit for calculating the noise amount of the synchronization signal. A noise component calculation circuit and a burst signal detection/calculation circuit that extracts a burst signal from a video signal and calculates its amplitude are added, and the image quality state of the detection output point is fed back to the image quality adjustment circuit. The aim is to equalize the image quality.

[Operation] According to the present invention, between the video detection circuit and the image quality adjustment circuit, there are provided a synchronization signal detection circuit for extracting a synchronization signal from a video signal, and a noise component calculation circuit for calculating the noise amount of the synchronization signal. A burst signal detection/calculation circuit that extracts the burst signal from the video signal and calculates its amplitude is added, and the image quality state at the detection output point is fed to the image quality adjustment circuit, so the image quality can be made uniform. In addition, there is no need for adjustment when switching channels, and variations in the band characteristics of the tuner can be suppressed, so that inexpensive products can be used, and as a result, manufacturing costs can be reduced.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a video signal line of a television receiver including an automatic video quality adjustment circuit according to an embodiment of the present invention. In the figure, (1) selects and amplifies a desired radio wave from the TV radio waves. , intermediate frequency (58,75MHz)
(2) is an intermediate frequency amplification circuit that amplifies the intermediate frequency from the tuner; (3) is a video detection circuit that demodulates the intermediate frequency signal and converts it into a video signal; (4)
is an image quality adjustment circuit that adjusts image quality (video signal); (5)
amplifies the video signal for application to the picture tube.

In the existing circuit configured as described above, the present invention exemplified in this embodiment particularly includes a synchronization signal detection circuit (6) that extracts a synchronization signal from a video signal, and a noise component that calculates the amount of noise in the synchronization signal. The unique feature is that it includes a calculation circuit (7) and a burst signal detection/calculation circuit (8) that extracts a burst signal from a video signal and calculates its amplitude.

Next, the operation of the above configuration will be explained.

First, a tuner (1) selects and amplifies a desired radio wave from the television radio waves, and converts it into an intermediate frequency signal (58.75 MHz). Next, the intermediate frequency amplification circuit (2) optimizes and amplifies the band of the signal obtained from the chiquena (1).

A video detection circuit (3) demodulates the intermediate frequency signal and outputs a video signal. This video signal is subjected to image quality correction such as overshoot and preshoot in an image quality adjustment circuit (4), and amplified to a signal level to be applied to the picture tube in a video amplification circuit (5). At this time, the burst portion of the video signal obtained by the video detection circuit (3) is detected and calculated by the burst signal detection/calculation circuit (8) to detect subtle variations in image quality between channels due to variations in the tuner band. ,
By feeding this value back to the image quality adjustment circuit, it is possible to automatically maintain a constant image quality.

However, since the burst amplitude ζ image quality is achieved in a range where the electric field is strong to some extent, there is no effect when the electric field is weak. Therefore, in order to know the state of the electric field, a synchronous signal detection circuit (6),
A noise component calculation circuit (7) is installed to detect the amount of noise in the synchronization signal part, wire it with the value obtained by the burst signal detection/calculation circuit, and feed it back to the image quality circuit, making it possible to cope with weak electric fields. I'm trying to make it possible.

Further, in the above embodiment, a color television receiver has been described, but a VTR or other receiver may be used, and the same effects as in the above embodiment can be obtained.

(Effects of the Invention) As described above, according to the present invention, the image quality state of the detection output point is fed back to the image quality adjustment circuit, so even if an inexpensive tuner is used, the image quality between channels can be improved. This has the effect of automatically equalizing the amount of water and simplifying the adjustment.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a video signal line of a television receiver including an image quality adjustment circuit according to an embodiment of the present invention, and FIG. 2 is a video block diagram of a conventional color television receiver. (])...Tuner, (2)...Intermediate frequency amplification circuit, (3)...Video detection circuit, (4)...Picture quality adjustment circuit, (5)...Video amplification circuit, ( 6)...Synchronization signal detection circuit, (7)...Noise component calculation circuit, (8)...
...Burst signal detection/calculation circuit. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A tuner, an intermediate frequency amplification circuit that amplifies the intermediate frequency from the tuner, a video detection circuit that demodulates the intermediate frequency signal and converts it into a video signal, an image quality adjustment circuit that adjusts the video signal, and an image receiving circuit. In a video processing circuit equipped with a video amplification circuit for amplifying the signal level applied to a video signal, a synchronization signal detection circuit extracts a synchronization signal from a video signal, and a noise component calculation circuit for calculating the amount of noise in the synchronization signal. and a burst signal detection/calculation circuit that extracts a burst signal from a video signal and calculates its amplitude, and is configured to feed back the image quality state of the detection output point to the image quality adjustment circuit. Image quality adjustment circuit.