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. 18, 2002
Filed:
Nov. 23, 1999
Takahiro Sakaguchi, Kokubunji, JP;
Teac Corporation, Tokyo, JP;
Abstract
An encoder device has a main scale with a plurality of slit-like openings at regular intervals, light-emitting means for emitting and directing light toward the main scale, light-receiving means including four light receiving members for receiving light emitted from the light-emitting means via the slit-like openings in the main scale, and means for obtaining information concerning displacement of the main scale by using output signals output from the light-receiving means. The first and the second light-receiving members are disposed with respect to the slit-like openings of the main scale so as to have substantially the same phase, and the third and the fourth light-receiving members are disposed with respect to the slit-like openings of the main scale so that a first differential output signal, obtained by differentially amplifying an output signal output from the first light-receiving member and an output signal output from the third light-receiving member, and a second differential output signal, obtained by differentially amplifying an output signal output from the second light-receiving member and an output signal output from the fourth light-receiving member, have the same period and a predetermined phase difference. The first and second light-receiving members can be spaced further apart and the effects of light leaked when a given opening is between the first and second light-receiving members can be eliminated, making it possible to bring the light-emitting member and the light-receiving members closer together and thus make the encoder device slimmer.