Control circuit for controlling light source in optical disc device
Driving apparatus for semiconductor laser
Apparatus for controlling the write beam in an optical data recording system
Automatic power control for modulated LED photoelectric devices Patent #: 4598198
ApplicationNo. 06/758807 filed on 07/25/1985
US Classes:250/205, Controlling light source intensity250/214C, Compensation369/116Light intensity adjustment or maintenance
ExaminersPrimary: Nelms, David C.
Attorney, Agent or Firm
International ClassesH01S 5/0683 (20060101)
G11B 7/125 (20060101)
H01S 5/00 (20060101)
Foreign Application Priority Data1984-07-27 JP
AbstractA semiconductor laser drive circuit functioning as a light source of an optical recording/reproducing apparatus using an optical disk. In the recording mode, the input light of a semiconductor laser is modulated by a recording signal, the output light of the semiconductor laser is detected as a monitor signal by a photo sensitive device, the peak value of this monitor signal is held by a peak-hold circuit, a differential compensation control signal is obtained from the output of the peak-hold circuit and is fed back, and a photo control system to control the output light to a constant level is constituted, thereby controlling in such a way that the output light of the semiconductor laser becomes a certain constant modulation amplitude. Even upon recording, the output light can be stably controlled within a wide temperature range even if the characteristic of the semiconductor laser changes with the elapse of time. Also, this drive circuit can be realized by a simple arrangement.