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:
Mar. 06, 2001
Filed:
Apr. 30, 1999
Tsukasa Kosuda, Matsumoto, JP;
Yutaka Kondo, Matsumoto, JP;
Hajime Kurihara, Shimosuwa-machi, JP;
Norimitsu Baba, Shimosuwa-machi, JP;
Seiko Epson Corporation, Tokyo, JP;
Abstract
When emitted light from LED,is incident on photodiodes,and,with luminance Pa and Pb, currents ia and ib are generated according to luminance Pa and Pb. When outside light is incident through the finger tissues on photodiodes,and,with luminance Pc, current ic is produced. The current i,(=ia+ic) generated by photodiode,and the current i,(=−ib−ic) generated by photodiode,are added at node X, and the current ic corresponding to outside light is thus cancelled. In addition, photodiodes,and,are disposed at different distances from LED,As a result, the current flowing to opamp,is current ia corresponding to luminance Pa because luminance Pb is extremely low. The opamp,then applies a current voltage conversion to generate pulse wave signal Vm.