Apparatus and method for controlling optical disc write power
AssigneeNEC Corporation
InventorHiroyuki Hishiyama
Life of this patent
Estimating the term…
Abstract
A simply structured apparatus according to the present invention corrects an overdrive power level. A main controller allows an overdrive power generator to set an overdrive power current to zero, allows a base power controller to control a base power current with the target value of a base power monitor level set to a desired overdrive power level. When the base power monitor level has reached the target value, the main controller allows said overdrive power generator to increase the overdrive power current until a base power control signal monitored by a base power control signal monitor reaches a value corresponding to a desired base power level.
Claims14
An apparatus for controlling power to be supplied to a laser diode for writing on an optical disc, wherein one pulse of the power is composed of an overdrive power level and a base power level that follows the overdrive power level, the overdrive power level being higher in level and narrower in width than the base power level, the base power level corresponding to a base power current, the overdrive power level corresponding to a sum of the base power current and an overdrive power current, said apparatus comprising:
- a base power control signal monitor that monitors the base power control signal;
- an LD (Laser Diode) output level monitor that monitors a power level output by said laser diode;
- a base power controller that controls the base power current so that a power level monitored by said LD output level monitor matches a preset target value;
- an overdrive power generator that generates the overdrive power current;
- and
- a main controller that, at a correction time of the power level, allows said overdrive power generator to set the overdrive power current to zero, that allows said base power controller to increase the base power current with a target value of the base power level set to the overdrive power level that is desired, and that, when the base power level has reached the target value, allows said overdrive power generator to increase the overdrive power current until the base power control signal monitored by said base power control signal monitor reaches a value corresponding to a desired base power level.
A method for controlling power to be supplied to a laser diode for writing on an optical disc, wherein one pulse of the power to be supplied to said laser diode is composed of an overdrive power level and a base power level that follows the overdrive power level, the overdrive power level being higher in level and narrower in width than the base power level, the base power level corresponding to a base power current, the overdrive power level corresponding to a sum of the base power current and an overdrive power current, said method comprising the steps of:
- providing a base power control signal monitor that monitors the base power control signal;
- an LD output level monitor that monitors a power level output by said laser diode;
- a base power controller that controls the base power current so that a power level monitored by said LD output level monitor matches a preset target value;
- and an overdrive power generator that generates the overdrive power current;
- and
- at a correction time of the power level,
- setting, by said overdrive power generator, the overdrive power current to zero;
- increasing, by said base power controller, the base power current with a target value of the base power level set to the overdrive power level that is desired;
- and
- when the base power level has reached the target value, increasing, by said overdrive power generator, the overdrive power current until the base power control signal monitored by said base power control signal monitor reaches a value corresponding to a desired base power level.
Dependencies are inferred from the claim text.