| 摘要 |
<p>PURPOSE:To make output terminal voltages of photodetecting elements constant regardless of variance in characteristics among light emitting elements and the light receiving elements by providing a storage circuit where adjusting signals for adjusting a variable impedance circuit are stored previously by the couples of light emitting elements and light receiving elements. CONSTITUTION:The variable impedance circuit Q3 is connected to the light emitting elements L1-Ln in series and the storage circuit 9 is provided which is stored previously with the adjusting signals for adjusting the variable impedance circuit Q3 by the couples of the light emitting elements L1-Ln and light receiving elements PT1-PTn, thereby adjusting the variable impedance Q3 with an adjusting signal read out of the storage circuit 9. Therefore, even if the light emitting elements L1-Ln and light receiving elements PT1-PTn have variance in characteristics, the light emitting elements can be driven so that the output terminal voltages of the light receiving elements are constant.</p> |
