| 摘要 |
PURPOSE:To facilitate stable constant light emission without being influenced by the fluctuatoni of temperature by connecting an optical semiconductor device to a light emitting diode in parallel. CONSTITUTION:A basic circuit of a light emitting circuit 10 is composed of a resistance 11 and a light emitting diode 12 which are connected in series and grounded. A parallel circuit 14, branched from the resistance 11, is composed of a phototransistor 13, which is an optical semiconductor devide. The light emitted from the light emitting diode 12 enters the phototransistor 13. Therefore, if temperature changes, the resistance 11 is also changed. When the resistance 11 becomes large, the current applied to the diode 12 is reduced so that the luminance entering the phototransistor 13 is also reduced and the collector potential of the transistor 13 is elevated. Therefore, the current applied to the light emitting diode 12 is increased and hence and luminance is increased accordingly and when the luminance of the original condition is recovered, the circuit is balanced and the light emission becomes stable. On the other hand, if the resistance 11 becomes small, the balanced condition can be obtained by the process opposite to the process as described above. |
