Automatic beam limiter circuit
First Claim
1. An automatic beam limiter circuit for controlling a brightness/contrast of a video signal input to a cathode-ray tube (CRT) comprising:
- a conversion circuit for converting an analog signal to a digital signal, wherein the analog signal is generated from the video signal;
a horizontal average circuit for calculating a horizontal average of at least a portion of the digital signal;
a vertical average circuit for calculating a vertical average of the horizontal average;
a comparison circuit for comparing a first calculation value calculated between a reference value and the vertical average with a second calculation value calculated between the reference value and the horizontal average, and outputting a first comparison signal and a second comparison signal based on the comparison results; and
a gain control circuit for producing a gain control signal in response to the first comparison and second comparison signals for adjusting the brightness/contrast of the video signal input to the CRT.
1 Assignment
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Accused Products
Abstract
An automatic beam limiter circuit (ABL circuit) calculating an average of a video signal at least a portion of the video signal is provided. After a converter circuit converts an analog signal, which is generated from the video signal, to a digital signal, a horizontal and a vertical average circuits calculate a horizontal and vertical averages of the digital signal at least a portion of the digital signal. The portion of the digital signal is a scanned line of the digital signal on a CRT. A comparison circuit compares a first calculation value calculated between a reference value and the vertical average with a second calculation value calculated between the reference value and the horizontal average, and outputs a first comparison signal and a second comparison signal based on the comparison results. A gain control circuit produces a gain control signal for adjusting the brightness/contrast in response to the first comparison and second comparison signals. Advantageously, the automatic beam limiter circuit is capable of efficiently preventing a frame delay in controlling the brightness/contrast of the video signal and the rapid increase of beam current when a black field is rapidly changed into a white field.
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Citations
10 Claims
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1. An automatic beam limiter circuit for controlling a brightness/contrast of a video signal input to a cathode-ray tube (CRT) comprising:
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a conversion circuit for converting an analog signal to a digital signal, wherein the analog signal is generated from the video signal;
a horizontal average circuit for calculating a horizontal average of at least a portion of the digital signal;
a vertical average circuit for calculating a vertical average of the horizontal average;
a comparison circuit for comparing a first calculation value calculated between a reference value and the vertical average with a second calculation value calculated between the reference value and the horizontal average, and outputting a first comparison signal and a second comparison signal based on the comparison results; and
a gain control circuit for producing a gain control signal in response to the first comparison and second comparison signals for adjusting the brightness/contrast of the video signal input to the CRT. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A television receiver including an automatic beam limiter circuit for controlling a brightness/contrast of a video signal input to a cathode ray tube (CRT), wherein the automatic beam limiter circuit comprising:
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a conversion circuit for converting an analog signal to a digital signal, wherein the analog signal is generated from the video signal;
an average calculator for calculating a horizontal average and a vertical average of the digital signal at least a portion of the digital signal;
a comparison circuit for comparing a first calculation value calculated between a reference value and the vertical average with a second calculation value calculated between the reference value and the horizontal average, and outputting a first comparison signal and a second comparison signal, wherein the first comparison signal is the first calculated value, and the second comparison signal is zero (0) or the second calculated value according to the comparison results; and
a gain control circuit for producing a gain control signal in response to the first comparison and second comparison signals for adjusting the brightness/contrast of the video signal input to the CRT. - View Dependent Claims (8, 9, 10)
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Specification