Patent ID: 8174938
Filing Date: 2012-05-08
Classification: G11B

Abstract:
1. An optical disc device comprising: a spindle motor configured to rotate an optical disc comprising a variable area including reflectance or transmittance cyclically varying; an optical pickup configured to irradiate laser light onto the optical disc, and to receive reflected light from the optical disc, and to move in the radial direction of the optical disc by a lens actuator; a feed motor configured to move the optical pickup in the radial direction; an encoder board provided along the movement direction of the pickup and including transmittance or reflectance cyclically varying; a pickup position sensor comprising a first emission section configured to move following the movement of the optical pickup and to concurrently irradiate light onto the encoder board, and a first light receiver configured to receive reflected light or transmitted light of light irradiated onto the encoder board; a pickup position detection section configured to detect a position of the optical pickup in accordance with an output signal from the first light receiver of the pickup position sensor; a rotation encoder comprising a second light emission section configured to irradiate light onto the variable area of the optical disc, and a second light receiver configured to receive a reflected light or a transmitted light of the light irradiated onto the variable area; a 1/m rotation detector configured to count the signal outputted from the rotation encoder, and to output 1/m rotation information indicating 1/m rotation of the optical disc each time a predetermined number of the signals counted wherein m is an integer greater than or equal to 2; a control section configured to vary an objective position of the pickup in units of the 1/m track each time the 1/m rotation information is outputted from the 1/m rotation detector for forming dot marks on the label surface of the optical disc in spiral, and to control the movement of the pickup by driving the feed motor and/or the lens actuator according to position error information in correspondence to the objective position and the position of the pickup detected by the pickup position detection section, and a rotation control section configured to control the rotation of the optical disc in accordance with the signal outputted from the second light receiver of the rotation encoder so that a linear velocity of the optical disc is made constant.