| 摘要 |
PROBLEM TO BE SOLVED: To obtain a control method in which various kinds of compact disks can be driven so as to be compatible by a method wherein the reflectance with reference to a laser beam of every compact disk is reflected. SOLUTION: A laser diode LD emits light by a driving current I from a laser-diode drive part 201, the light is detected by a photodiode PD, and a feedback current If is made to flow to a level control part 204. On the other hand, an RF-signal level detector 202 detects an RF signal at a compact disk drive, a high-frequency component in a detection current Ir is removed by a low-pass filter 203, and a current Ir' is output to the level control part 204. The level control part 204 controls the feedback current If on the basis of the current Ir', and it outputs a current If' so as to be supplied to the laser-diode drive part 201. Then, the laser-diode drive part 201 outputs the driving current I which is in inverse parallel to the input feedback current If', and the reflectance of a compact disk is reflected. |
