Optical encoder

Abstract

Abstract PURPOSE:To detect the absolute position of an optical disk at the time of the recovery from a power failure without any angle variation by providing the optical disk with a 1st pit which function as an incremental encoder and plural 2nd pits whose absolute positions are coded radially. CONSTITUTION:The optical disk 3 which is fitted to a rotary body and rotates together with the rotary body is provided with the plural its 7 on a track 6 at equal intervals l1 to equal length l2 and width 1d. Pits 11-14 which differ in length and interval are formed on tracks 15-18 inside the track 6. The diameter d2 of the spot 8 of laser light is smaller than the lengths l1 and l2. When the optical disk stops rotating temporarily owing to a power failure and is restrarted, a tracking servomechanism moves the spot 8 radially. For example, the spot moves in the direction of, for example, a diameter 35, the absolute value is found as '1011'. Consequently, the disk is easily and accurately restarted after the power failure.

Inventors

• 👤 Gensuke Okada
• 👤 岡田　愿介
• 👤 Takao Wada
• 👤 多加夫 和田

Bibliographic Details