Horizontal Synchronizing Signal Generator
Original Publication Date: 1987-Sep-01
Included in the Prior Art Database: 2005-Feb-01
A horizontal synchronizing (H-SYNC) signal generator comprises means for maintaining stability of the H-SYNC signal when a number of columns to be displayed is changed. As shown in Fig. 1, a display station includes a flip-flop 7 for producing a H-SYNC signal. The flip-fop 7 is adapted to be set by an output of a comparator 5 and reset by an output of an another comparator 6. Each comparator receives an output of a column counter 8 on one of its two input terminals. Assuming that the display is operable in either 80- or 132-column mode, the column counter 8 is caused to count from "0" to "99" repeatedly in response to a clock signal of first frequency in the 80-column mode. In the 132-column mode, the column counter 8 is caused to count from "0" to "164" repeatedly in response to a clock signal of second frequency.