| 摘要 |
PURPOSE:To protect a laser diode(LD) against deterioration or breakage by a method wherein the temperature of the LD is detected, and an LD drive signal is transmitted only when an element temperature stays within a range of an operating temperature. CONSTITUTION:An LD 3 transmits an optical signal 05 basing on a signal 01 of a drive circuit 1. A thermosensor 5 supplies the temperature of the LD 3 to both a protective circuit 6 and a drive circuit 7. The drive circuit 7 sends a drive current 02 basing on the information 03 to a Pertier element 4 formed in an integral structure with the LD 3 through a low thermal resistor to control the temperature of the LD 3. The protective circuit 6 judged whether the temperature of the LD 3 stays within the range of an operating temperature or not basing on the temperature information 03 and transmits a protection signal 04. A drive circuit 1 transmits a drive signal 01 only when the signal 04 indicates that the temperature of the LD 3 stays within the range of an operating temperature. Therefore, an LD is prevented from emitting light when its temperature is out of the range of an operating temperature, so that the LD is protected against breakage and deterioration. |
