Laser driver, optical disk apparatus using the same, and laser control method
AssigneesHitachi, Ltd., Hitachi-LG Data Storage, Inc.
InventorsMakoto Nihei, Toshimitsu Kaku, Akihiro Asada, Takashi Hoshino
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Abstract
An optical disk apparatus uses a laser driver which can measure the frequency of the high-frequency superimposed current of the semiconductor laser simply and accurately. The apparatus includes a semiconductor laser which emits a laser beam onto the optical disk, a laser driver which drives the semiconductor laser with a current, with the high-frequency current being superimposed thereon, and measures the frequency of the high-frequency current, and a main controller which controls the frequency of the high-frequency current produced by the laser driver by using the frequency measured by the laser driver.
Claims14
An optical disk apparatus comprising:
- a semiconductor laser which emits a laser beam onto an optical disk;
- a semiconductor laser driver which drives said semiconductor laser with a current, with a high-frequency current being superimposed thereon, and measures the frequency of the high-frequency current;
- and a main controller which controls the frequency of the high-frequency current produced by said semiconductor laser driver by using the frequency measured by said semiconductor laser driver.
An optical disk apparatus for reproducing data recorded on an optical disk, said apparatus having a semiconductor laser which emits a laser beam onto said optical disk, an optical head on which said semiconductor laser is fitted, a laser driver which controls the output of said semiconductor laser, and a main controller which controls said optical head and said laser driver,
- wherein said laser driver includes a semiconductor laser drive circuit which feeds a d.c. current to said semiconductor laser, a high frequency superimposing oscillator which produces a high-frequency current to be superimposed on the output current of said semiconductor laser drive circuit, and a frequency measuring circuit which measures the frequency of the high-frequency current produced by said high frequency superimposing oscillator and indicates the measured frequency to said main controller.
A laser driver which controls a semiconductor laser which emits a laser beam onto an optical disk, said laser driver including a semiconductor laser drive circuit which feeds a d.c. current to said semiconductor laser;
- a high frequency superimposing oscillator which superimposes a high-frequency current on the output current of said semiconductor laser drive circuit;
- and a frequency measuring circuit which measures the frequency of the high-frequency current produced by said high frequency superimposing oscillator and outputs the measured frequency to the outside.
A laser control method for an optical disk apparatus which drives a semiconductor laser with a high-frequency current to emit a laser beam onto an optical disk and reproduces data recorded on said optical disk, said method comprising the steps of:
- measuring the frequency of the high-frequency current;
- and controlling the frequency of the high-frequency current by using the measured frequency.
An optical disk apparatus for reproducing data recorded on an optical disk by driving a semiconductor laser with a high-frequency current to emit a laser beam onto said optical disk, said apparatus comprising:
- means of measuring the frequency of the high-frequency current;
- and means of controlling the frequency of the high-frequency current by using the measured frequency.
Dependencies are inferred from the claim text.