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:
Nov. 20, 2007
Filed:
Nov. 28, 2002
Katsuichi Ohsawa, Osaka, JP;
Toyoyuki Shimazaki, Osaka, JP;
Tetsuo Chato, Katano, JP;
Yuzo Shimizu, Mishima-gun, JP;
Kenji Imaizumi, Takatsuki, JP;
Katsuichi Ohsawa, Osaka, JP;
Toyoyuki Shimazaki, Osaka, JP;
Tetsuo Chato, Katano, JP;
Yuzo Shimizu, Mishima-gun, JP;
Kenji Imaizumi, Takatsuki, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
The present invention is intended to prevent a light-emitting diode from emitting light continuously in the case when the level at an input terminal is fixed high because of software or the like and to avoid various problems, such as battery exhaustion and breakdown of the light-emitting diode, in PDAs, cellular phones, etc. For these purposes, a high-pass filterfor passing the high-frequency components of an optical transmission input signal having a pulse waveform and a binary circuitfor binarizing the output signal of the high-pass filterso as to be returned to a pulse waveform are provided in the preceding stage of a light-emitting device driving circuitfor driving a light-emitting diodefor optical transmission.