Recording body of high density information

Abstract

Abstract PURPOSE:To use both the recessed and projected parts of a recording body as information tracks by forming the recessed and projected parts of which height difference is larger than the focal depth of a condenser lens alternately in the radius direction of a substrate. CONSTITUTION:The recessed parts 32 and the projected parts 34 are alternately formed on the substrate 30 so as to be arrange with approximately eual intervals in the radius direction of the substrate 30. The height difference (d) of the recessed parts 32 and the projected parts 34 is determined so as to be larger than the focal depth of the condenser lens. Information recording parts 36 are formed on the surfaces of the recessed and projected parts 32, 34 respectively and both the recessed and projected parts 32, 34 are used as the information tracks 12. In auto-tracking servo, tracking is executed by detecting the difference of photodetecting quantity between A+D and B+C by a photodetector. The signals of A+D and B+C are amplified by amplifiers 60, 62 respectively and the difference of these signals is found out by a differential amplifier 64 to drive an actuator 24 through a phase correcting circuit 66 and a driver amplifier 68 and execute auto-tracking.

Inventors

• 👤 Kiyonobu Endo
• 👤 遠藤　清伸
• 👤 Hideki Hosoya
• 👤 細谷　英樹
• 👤 Hiroyasu Nose
• 👤 博康 能瀬
• 👤 Yasuo Nakamura
• 👤 保夫 中村

Bibliographic Details