JPS572166A - Distortion correcting circuit of pickup tube or the like - Google Patents

Abstract

PURPOSE:To reduce the leakage of a digital noize and thus ensure an effective correction of distortion over an entire region of a screen, by producing an interpolation coefficient between the key points through a multiplication-type D/A converter and then calculating the degree of each distortion correction through the said converter from the degree of distortion correction of the key point read out of a storage circuit. CONSTITUTION:Both horizontal and vertical driving signals HD and VD are supplied to a memory address -k signal generating circuit 2, and both horizontal and vertical address signals are applied to a storage circuit 3 from the circuit 2. The degree of key point is stored previously in the circuit 3, and the degree a1 of a key point and degree b1 of the other key point are supplied to D/A converters 4 and 5 respectively by the address signals corresponding to the synchronous signals. In the mean time, the n signal is supplied simultaneously to a D/A converter 6 from the circuit 2, and the analog output of degree K supplied from the converter 6 is applied to a reverse amplifier 7 and the converter 5. In addition, 1-k given from the amplifier 7 is applied to the converter 5. Then the degrees a1 and b1 are multiplied by k and k-1 through the converters 4 and 5. Thus a correction of distortion is carried out over an entire region of a screen.