Patent ID: 6678230
Filing Date: 2004-01-13
Classification: G11B

Abstract:
A waveform equalizer that equalizes a waveform of a reproduction signal obtained by reproducing marks and non-marks recorded on a recording medium, comprising:a delay element that delays a propagation of the reproduced signal; a plurality of multipliers that multiply predetermined coefficients by the reproduction signal and the delayed signal from the delay element; a coefficient learning circuit that adaptively updates the predetermined coefficients for each of the plurality of multipliers; and an adder that adds outputs from the plurality of multipliers, said coefficient learning circuit comprising: a teaching signal generator that generates a teaching signal that serves as an equalizing target; an error detector that detects an error between an output signal having an impulse response of (a, b, b, a) characteristics and the teaching signal generated by the teaching signal generator; a discriminator that discriminates the marks and the non-marks based on the reproduction signal to output a discriminating signal; a plurality of registers that update and output the predetermined coefficients so that a mean square of the error becomes minimum, said plurality of registers including a first register that holds a first coefficient multiplied by the reproduction signal of the marks and a second register that holds a second coefficient multiplied by the reproduction signal of the non-marks, which is different from the first coefficient; and a register selector that selects one of the first coefficient held in the first register and the second coefficient held in the second registers based on the discriminating signal outputted from the discriminator.