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:
Jan. 03, 2006
Filed:
May. 22, 2003
Tsukasa Hoshi, Sendai, JP;
Hiroshi Sakamoto, Tokyo, JP;
Tsukasa Hoshi, Sendai, JP;
Hiroshi Sakamoto, Tokyo, JP;
Freescale Semiconductor, INC, Austin, TX (US);
Abstract
A light-emitting element drive apparatus for achieving light-emission control of a light-emitting element with high speed and high accuracy includes a monitoring photodiodethat receives light emitted from a laser diodeto generate a current, Im, that corresponds to the optical output thereof. The current Im is converted to a monitor voltage Vm by a current-to-voltage conversion circuit, and its waveform is smoothed by a first low-pass filterto produce a monitoring average value Vav that has a ripple component. A pre-modulated optical power setup voltage Vps generated by a variable direct-current voltage sourceis modulated by a pulse modulation circuitbased on a data signal delayed by a predetermined time, and smoothed via a second low-pass filterand a third low-pass filter. Then, an optical power setup voltage Vref that has a nearly similar amplitude and ripple component is generated in synchronization with the average value Vav.