| 摘要 |
PURPOSE:To keep the steady-state operation of an automatic luminous energy control circuit for a laser beam by subtracting an averaging subtraction current generated based on a write signal during the write operation of an optical recorder from a detected current. CONSTITUTION:An automatic luminous energy circuit 3 is connected to a photodiode 2 to supply a steady-state driving current iLR to a laser diode 1. The steady-state driving current iLR is set by a 1st reference voltage VREF1. A current summation circuit 4 is connected to the laser diode 1 and a modulation driving current DELTAiLW subjected to pulse modulation by a write signal RS is summed to the steady-state driving current iLR and the result is supplied to the laser diode 1. Moreover, the level of a modulation driving current is set by a 2nd reference voltage VREF2. A subtraction current averaging circuit 5 is connected to the photodiode 2 and acts like eliminating a fluctuation detection current component in average due to the modulation driving current DELTAiLW included in a detection current IP at write. Thus, the steady-state operation of the automatic luminous energy control circuit is maintained even at write. |
