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:
Aug. 06, 2013
Filed:
Apr. 27, 2011
Jun Matsui, Kawasaki, JP;
Jun Matsui, Kawasaki, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
A device includes: a providing unit that provides a driving electric current to a semiconductor laser, the electric current being superimposed a first alternating current signal having a first frequency at a low side of an operational range of the semiconductor laser and a second alternating current signal having a second frequency at a high side of the operational range; a first filter that extracts a first component corresponding to the first frequency from a voltage to be applied to the semiconductor laser; a second filter that extracts a second component corresponding to the second frequency from the voltage to be applied to the semiconductor laser; and a judge circuit that judges a state of the semiconductor laser based on a first differential resistance obtained from the result of the extracting by the first filter and a second differential resistance obtained from the result of the extracting by the second filter.