Patent ID: 6580580
Filing Date: 2003-06-17
Classification: G11B

Abstract:
A magnetic memory drive, which comprises:a light source which emits a light beam; a diffraction grating which receives the beam emitted by the light source to generate three beams of 0th-order and Â±1st-order light beams; a condensing system which converges the beams generated from the diffraction grating into a minute spot on a magnetic recording medium on which periodic physical variations are formed for providing variations in reflectivity; a photodetector which receives the beams reflected and diffracted from the magnetic recording medium and again passing through the condensing system and outputs signals corresponding to quantities of the received beams; a signal processor which processes the signals outputted from the photodetector to output a tracking error; a driver which receives the tracking error signal outputted from the signal processor and positions the beams on a desired track; and a magnetic head which records information on the magnetic recording medium or reproduces or erases information on the magnetic recording medium; wherein the photodetector comprises a plurality of light-receiving sections, and when crosstalk from a light-receiving section for the 0th-order beam to light-receiving sections for the Â±1st-order beams is &egr; and crosstalk from the light-receiving sections for the Â±1st-order beam to the light-receiving section for the 0th-order is &egr;â€² in the light-receiving sections of the photodetector, quantity of light Q0 of the 0th-order light beam and quantity of light QÂ±1 of the Â±1st-order light beams has a relationship represented by a following equation: Q0&it;:&it;Q&PlusMinus;1=2Ã—&varepsilon;â€²&varepsilon;&it;:&it;1.