| 摘要 |
PURPOSE:To compensate the temperature characteristic of an LED effectively with a simple circuit by coupling an input section of a drive circuit with a pre-stage by using a coupling element having a temperature characteristic opposite to that of a light emitting diode element. CONSTITUTION:A temperature characteristic is provided to a level shift of a voltage level shift circuit by connecting each output of an amplifier 3 and each base of transistors (TRs) 1a, 1b by coupling elements 4a, 4b having an opposite temperature characteristic to that of the LED. That is, in inserting an element whose resistance varies with the temperature, for example, the base potential of the TR has a temperature characteristic, resulting that the current flowing to the TR (LED drive current) varies with the temperature characteristic. Thus, the temperature characteristic of the light emission power of the LED is compensated by having only to select the coupling elements 4a, 4b having a proper temperature characteristic. |
