| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an LED drive circuit in which the load of a power supply is reduced by eliminating simultaneous turn on of multiple LEDs. <P>SOLUTION: Cathode lines X1-X4 are arranged in the direction intersecting anode lines Y1-Y4. Sixteen LEDs are arranged, respectively, for the intersections of the anode lines Y1-Y4 and cathode lines X1-X4. Four PWM circuits are connected, respectively, with the cathode lines X1-X4. Each PWM circuit includes a current source 11-m, a counter 13-m, a comparator 12-m which compares display data Dm with the counter output from the counter 13-m, and N channel MOS transistors T5-T8 which supply the current of the current source 11-m to a corresponding LED according to the output COm from the comparator 12-m. Output phases of the counter 13-m are shifted from each other. <P>COPYRIGHT: (C)2012,JPO&INPIT |
