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:
Jun. 04, 2002
Filed:
Dec. 16, 1998
Toshihiro Shigemori, Kanagawa, JP;
Ricoh Company, Ltd., Tokyo, JP;
Abstract
A first current flows through a laser diode, a second current flows through the laser diode in addition to the first current, and a third current flows through the laser diode in addition to the first and second currents. First and second switches allow the second and third currents to be provided to the laser diode and prevent the second and third currents from being provided to the laser diode. First and second pulse generators provide first and second on-off signals each having a pulse-series waveform to the first and second switches in accordance with an information code. A timing unit generates a timing signal for preventing the first and second on-off signals from being provided to the first and second switches. Output of a photo detector is sampled during a period during which the timing signal is generated, and is sampled during a period during which the first on-off signal is in an H level and the second on-off signal is in an L level. The first and second currents are adjusted depending on the thus-sampled outputs of the photo detector. The third current is adjusted so as to have the value obtained as a result of the value of the second current being multiplied by a predetermined coefficient.