JPS6486794A - Image memory controller - Google Patents

Abstract

PURPOSE:To shift the phase of a burst signal by 180 deg. between fields at the time of reproducing a still picture with a simple constitution by switching the initial value of a horizontal counting means so as to shift the phase of a chrominance subcarrier read out from an image memory at every frame. CONSTITUTION:In case of reproducing the still picture, a readout pulse RE is generated after writing data of one field on the image memory 24, and the data of one field is read out repeatedly. In such a case, a frame discrimination circuit 30 to keep the continuity of the burst signal is provided, and a frame discrimination pulse LD which repeats an 'H' level and an 'L' level at a frame cycle is inputted to a horizontal counter 25. Since the output data HADRS of the horizontal counter 25 designates a readout address in a horizontal direction, the data can be read out by a clock CK from a timing signal generation circuit 23 earlier by two clocks in an odd frame compared with an even frame. Here, since the frequency of the CK is provided with the frequency of four times that of the chrominance subcarrier, the phase of the burst signal read out at the odd frame is inverted by 180 deg..