Optical disk reproducing device

Abstract

Abstract PURPOSE:To enable high speed access by changing the center frequency of a phase locked loop to generate a reproduced output so as to correspond to a linear velocity, in a state that the rotation speed of an optical disk is controlled to be constant. CONSTITUTION:The revolution of the optical disk 1 is controlled so as to be at a prescribed angular velocity by a spindle control part 2, a phase comparator 3 and a crystal oscillator 4. When a signal from the disk 1 is read by a pickup 5, this signal comes to be the binary signal of a high and a low levels, and is inputted to a Tmax detecting part 8 and the phase locked loop (PLL) consisting of the phase comparator 12, an LPF 13 and a voltage controlled oscillator 11. At that time, the least time width Tmax comes to be the one corresponding to the linear velocity at the time of reproduction. Through the use of such constitution, the center frequency of the PLL varies as following the linear velocity, and is transmitted as a system clock. Thus, seek time can be speeded up, and the high speed access comes possible.

Inventors

• 👤 Hiroshi Ogawa

Bibliographic Details