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:
Oct. 09, 2001
Filed:
Feb. 23, 1999
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
A first embodiment of an illumination source including red LEDs, green LEDs, and blue LEDs provides illumination for a scanner. The LEDs are arranged in an array to generate spectrally and spatially substantially uniform illumination on the surface of an object, such as printed media, which is to be scanned. The arrangement of LEDs includes a plurality of groups of three LEDs. Each group of LEDs includes a red LED, a green LED, and a blue LED. The LEDs of like colors are connected in series. Power is supplied to the three groups of series connected LEDs by three current sources. The three current sources are each configured to supply a constant current to one of the groups of series connected LEDs. Each current source supplies a magnitude of current so that the resulting light provides substantially uniform illumination on the printed media. A second embodiment of the illumination source includes LEDs that can each generate light having a substantially uniform energy spectrum over the range of visible light frequencies. A third embodiment of the illumination source includes a plurality of groups of four LEDs. Each of the groups of LEDs includes a red LED, a green LED, a blue LED, and a yellow LED.