| 摘要 |
PURPOSE:To obtain an light emitting source ON/OFF circuit capable of operating in a high-speed by outputting a pulse current and a bias current corresponding to the data inputted via a logical multiply means and the control voltage. CONSTITUTION:When the active status of shutdown signal is set to 0 and the inactive status thereof 1, respectively, '1' of the shutdown signal SD is supplied to one input terminal of a logical multiply means 20 and the data D of '1' is supplied to the other input terminal thereafter. Then, the data D is sent to an APC circuit 8 via a drive circuit 1, the first filter 4 and an adder 7, and the circuit 8 outputs a control voltage VC and the circuit 1 outputs bias current IB and pulse current IP to an light emitting source module 2 to turn on and start emission. Thus, an optical signal OS is converted into an electric signal during the output of the optical signal OS and is feedbacked. Therefore the timing of the module 2 ON/OFF becomes dependent on the response time of the means 20 and the circuit 1, resulting in high-speed ON/OFF operation for the light emitting source. |
