Patent ID: 7474603

Claim:
A laser control circuit adapted to modulate a light intensity of a laser beam irradiated for recording multilevel information on an optical information recording medium, wherein an area of the optical information recording medium is divided into approximately uniform cells, and marks that can be formed in a plurality of sizes are recorded on the cells according to the multilevel information being recorded by adjusting a time width of a bias power period and an off power period of the laser beam, said laser control circuit comprising: a unit that inputs a clock signal indicating a cell frequency and the multilevel information corresponding to each cell, and determines a laser beam emission waveform for each cell based on the input clock signal and multilevel information, wherein a period of an n-multiplied frequency (n being an integer) of the clock signal indicating the cell frequency is used as a step in setting the laser beam emission waveform, and wherein the time width of the bias power period is based on an equation: Tb =( a− 1) Tx+Ty, where Tb is the time width of the bias power period, a is a multilevel value, Tx is a unit of time width, and Ty is a time width provided for each level of multilevel information.