Patent ID: 7719942

Claim:
A power controlling method for controlling a power of an optical disc drive when recording data in an optical disc, the power controlling method comprising: executing a first predetermined procedure to obtain a first predetermined control signal corresponding to a first predetermined power needed by a pick-up head to record the data in the optical disc; receiving data comprising a plurality of first bits with a first voltage level and a plurality of second bits with a second voltage level; enabling a sample/hold circuit of a power control unit upon receiving the first bits with the first voltage level to make the pick-up head and the power control unit form a closed loop; providing the first predetermined control signal to the power control unit to cause it to generate a first control voltage to drive the pick-up head to output a first power; providing a first control signal to drive the pickup head to output a power substantially equivalent to a first test power; providing a second control signal to drive the pickup head to output a power equal to a second test power; establishing a first comparing curve according to the first and second control signals and corresponding the first test power and the second test power, wherein the first comparing curve represents a function relationship between control signals of an digital-to-analog converter and the output powers of the pickup head; calculating a difference between the first power and the first predetermined power utilizing a second comparing curve to calculate a control signal corresponding to an optimum recording power, wherein the first predetermined power is utilized as the optimum recording power to record the optical disc, wherein the second comparing curve is generated by utilizing the difference to shift the first comparing curve; and adjusting a second predetermined power to generate a third predetermined power according to the difference when the optical disc drive executes a second predetermined procedure to obtain a second predetermined control signal corresponding to the second predetermined power needed by the pick-up head to record the data in the optical disc, wherein the second predetermined procedure is configured to utilize the first comparing curve to determine the first predetermined control signal corresponding to the first predetermined power, and determine the second predetermined control signal corresponding to the second predetermined power; wherein a third predetermined control signal corresponds to the third predetermined power, and the difference between the first power and the first predetermined power is substantially equivalent to a difference between the second predetermined power and the third predetermined power.