The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 03, 2009
Filed:
Sep. 09, 2004
Makoto Nihei, Hitachinaka, JP;
Toshimitsu Kaku, Sagamihara, JP;
Akihiro Asada, Chigasaki, JP;
Takashi Hoshino, Yokohama, JP;
Makoto Nihei, Hitachinaka, JP;
Toshimitsu Kaku, Sagamihara, JP;
Akihiro Asada, Chigasaki, JP;
Takashi Hoshino, Yokohama, JP;
Hitachi, Ltd., Tokyo, JP;
Hitachi-LG Data Storage, Inc., Tokyo, JP;
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.