Optical recording and reproducing device

Abstract

Abstract PURPOSE:To obtain an invariably constant servo loop gain regardless of the mode of the device, i.e. recording, reproduction, or erasure by varying the gains of respective amplifiers in a focus and a tracking servo circuit automatically according to variation in the quantity of reflected light of the optical recording and reproducing device. CONSTITUTION:The focus servo circuit and tracking servo circuit constitute a focus servo loop and a tracking servo loop respectively. The focus servo circuit inputs outputs of two divided photodetecting elements 15 and 16 to a differential amplifier 24 as a sum signal and the signal is further inputted to a polygonal approximating circuit 26 through a differential amplifier. This sum signal voltage is converted into a desired voltage and characteristics and the gains of gain control circuits 27 and 33 are controlled with the output voltage of the polygonal approximating circuit 26 to make the servo loop gains invariably constant.

Inventors

• 👤 Yoshio Miura
• 👤 三浦　芳夫
• 👤 Motoyuki Suzuki
• 👤 基之 鈴木

Bibliographic Details