Optical disk apparatus
An optical disk apparatus includes a digital signal processor, a photo-detector circuit, and a sample-and-hold circuit. By using a sampling-timing signal generated by the sampling-timing signal based on a sampling-timing signal transmitted from the digital signal processor to the photo-detector circuit through a flexible cable, the sample-and-hold circuit can be operated. Based on a sampling-timing signal dedicated for a side spot, the sample-and-hold circuit can be operated.
1. An optical disk apparatus for obtaining a plurality of servo signals by separating a laser beam into at least two beams, converging said at least two beams on a first spot and at least one second spot on a recording medium, and photoelectrically converting reflected beams from the first spot and said at least one second spot at the time of recording data on the recording medium, the optical disk apparatus comprising:
first converting means for converting the reflected beam from the first spot into an electrical signal;
first sample-and-hold means for sampling and holding the electrical signal obtained by the first converting means;
second converting means for converting the reflected beam from said at least one second spot into an electrical signal;
second sample-and-hold means for sampling and holding the electrical signal obtained by the second converting means;
signal generating means for generating, based on a given first sampling-timing signal for determining sampling timing for the first sample-and-hold means, a second sampling-timing signal for determining sampling timing for the second sample-and-hold means; and
transmitting means for transmitting, to signal processing circuits at a subsequent stage, sampled-and-held signals obtained by the first and second sample-and-hold means.
2. The optical disk apparatus according to claim 1 , wherein, based on the generated second sampling-timing signal, the second sample-and-hold means samples and holds the electrical signal obtained by the second converting means in a period in which the laser beam is emitted at a bias power level.
3. The optical disk apparatus according to claim 1 , wherein, the signal generating means generates the second sampling-timing signal based on the first sampling-timing signal and a delayed signal obtained by delaying the first sampling-timing signal.
4. The optical disk apparatus according to claim 3 , wherein, before the first sampling-timing signal falls, the signal generating means generates the second sampling-timing signal only when the delayed signal rises.
5. The optical disk apparatus according to claim 1 , wherein the first and second converting means, the first and second sample-and-hold means, and the signal generating means are integrated into a single chip circuit.
6. The optical disk apparatus according to claim 1 , wherein, when the first spot is a main spot and the second spots are side spots, each of the side spots is radially disposed on the recording medium in a form shifted with respect to the main spot by half of a track pitch.