| 摘要 |
PROBLEM TO BE SOLVED: To realize a light emitting device drive circuit and a light emitting apparatus equipped therewith, wherein the light emitting apparatus is capable of stably emitting light independently of a variation in a power supply voltage and a change in ambient temperature. SOLUTION: A compensation circuit 20 is provided. The compensation circuit 20 is composed of a power supply voltage variation detecting circuit 21, a reference voltage source 22, and a current control circuit 23. The output of the current control circuit 23 is used for controlling a current fed from a constant current source 15 to make a bias current 1b applied to a light emitting device 11 constant. When a power supply voltage VCC varies, a first bias current Ibt varies, and a second bias current Ibc is controlled by the current control circuit 23, so as to cancel a change in the first bias current Ibt and to make the bias current Ib applied to the light emitting device 11 constant. When an ambient temperature changes, the constant current source 15 or the reference voltage source 22 is made to have temperature characteristics, whereby a bias current is changed corresponding to a temperature change, and a light emitting device can be kept constant in output. |
