Feedback control apparatus in an optical recording and reproducing device

Abstract

Abstract A feedback control apparatus in an optical recording and reproducing device for recording, reproducing and/or erasing data from an optical recording medium projects a light beam emitted from an optical head onto the optical recording medium. The apparatus includes an actuator for controlling the illuminating conditions of the light beam projected onto the optical recording medium, a detection unit for detecting the illuminating conditions of the light beam projected onto the optical recording medium, and a control amplifier for driving the actuator in accordance with a detection signal outputted from the detection unit, thereby controlling the illuminating conditions of the light beam projected onto the recording medium. The apparatus further includes a switching device for selectively switching from a detection signal from the detection unit to a reference signal, or vice versa, and for inputting into the control amplifier, the reference signal having the same signal level as that of a detection signal which is expected to be outputted from the detection unit when the illuminating conditions of the light beam projected onto the recording medium are appropriate. An offset compensation device outputs an offset compensation signal to the control amplifier. The offset compensation signal is set such that a control signal generated in the control amplifier has a predetermined signal level when the reference signal is inputted into the control amplifier. The apparatus prevents a DC offset from being included in the control signal from the control amplifier and reduces the procedures required for adjustment during the manufacturing process without employing expensive parts and devices and the like, thereby lowering the production costs.

Inventors

• 👤 Toshihisa Deguchi
• 👤 Tomiyuki Numata
• 👤 Masaru Nomura
• 👤 Kunio Kojima

Bibliographic Details