Patent ID: 7218582
Filing Date: 2007-05-15
Classification: G11B

Abstract:
1. An optical disc drive for reading and/or writing data from/on an optical disc having a data storage layer, the optical disc drive comprising: a light source for emitting light; a lens for converging the light; a photodetector for detecting the light reflected from the optical disc to output a read signal; at least one blocker for selectively outputting one of the read signal and a predetermined reference signal; a servo signal generator for generating a servo signal in response to the output signal of the blocker; an offset detector for detecting a first type of offsets that have been produced due to one of electric circuits of the servo signal generator, the offset detector detects output values of the servo signal generator as values of the first type of the offsets while the reference signal is output; a memory for storing the first type of offsets detected; a calculator for outputting one of the first type of actual offset and a second type of offset, as a correction value, the calculator deriving the second type of offset based on a variation rate of the first type of offsets stored; and a corrector for correcting the servo signal in accordance with the correction value.