Automatic gain controller of image display equipment and control method thereof

Abstract

The present invention relates to an automatic gain controller of image display equipment which automatically regulates the signal intensity of the image display equipment and a control method thereof. The method comprises the following steps: outputting the amplified signal under a certain gain controlling; detecting the intensity of synchronous signal in the output signal; detecting the white level in the outputting signal; detecting the black level in the outputting signal; amplifying or attenuating the outputting gain of the gain controller based on the relationship between the synchronous signal detected by the synchronous level detect part and the reference level and whether the white level or the black level is detected by the white level detect part or the black level detect part. Therefore, for the rapidly changed signal, the picture deterioration is effectively prevented and a stable operation is achieved by utilizing the noise signal even if the brightness level changes or it works under a weak electrical condition.

Description

technical field [0001] The invention relates to an automatic gain control device, in particular to an automatic gain control device of an image display device capable of automatically adjusting the signal strength of the image device and a control method thereof. Background technique [0002] Usually, imaging equipment does not receive radio waves at a constant intensity. Depending on the weather conditions it passes through, the radio wave may increase or decrease, and it is constantly changing. As a result, the brightness and contrast of the picture change due to the difference in the strength of the radio waves. In order to prevent this phenomenon from happening, an automatic gain control (AGC) voltage is applied to the transistors of the high frequency amplifier circuit or the intermediate frequency amplifier circuit. [0003] figure 1 It is a block diagram of an automatic gain control device of an existing imaging device. [0004] Such as figure 1 As shown, the aut...

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Problems solved by technology

[0014] However, if image 3 As shown, when the analog / digital conversion unit 12 outputs an abnormal signal containing noise, the noise is used to activate the white level detection unit 15, and the variable gain is continuously reduced until the white level detection unit 15 is not in operation. section 11 gain, changes the brightness level, darkens the screen

[0015] Therefore, the automatic gain control device of the above-mentioned existing video equipment has the following problems: It does not correspond to the signal change from weak current to strong current on the aforementioned line, and the situation of darkening the screen often occurs

In particular, under the signal condition of a sharply changing signal, the input signal changes rapidly. If the input signal is weak, the white level detection part performs operation due to noise, and the white level detection part is reduced until the white level detection part does not work. output gain, picture dimming

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