| 摘要 |
PURPOSE:To improve the reliability by controlling turning-on/off of the current of a light emitting diode with one display dot as the unit and collectively detecting the current of a common power line. CONSTITUTION:The collector of a transistor TR Tr1 which controls turning-on/off of the current is directly connected to the cathode of a light emitting diode D1 in a control circuit B, and the output of a storage circuit M where display data is stored is connected to a terminal O'. Final data of display data which controls turning-on/off of the current of each display dot is stored in a storage circuit MEM2 where monitor data is stored, and a match comparing circuit C compares data in both storage circuits MEM1 and MEM2 with each other to detect whether display data is correctly transmitted or not with one display as the unit. Thus, the reliability is improved.
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