OPTICAL ENCODER

WIPO Patent Application WO/2012/114595

A1

This optical encoder is provided with: an optical scale, which has optical patterns at regular intervals, and which can be relatively angularly displaced; a floodlight unit for projecting light toward the optical scale; a light receiving unit for receiving light from the optical scale; and a calculating unit for calculating an absolute rotation angle (θ) of the optical scale on the basis of signals transmitted from the light receiving unit. The optical patterns include a plurality of light blocking sections and a plurality of light transmitting sections, which are alternately disposed, and when the pitch of an nth light blocking section in the predetermined circumferential direction is represented by (Pn), and the width of the nth light blocking section is represented by (Wn), a transmissivity (T(θn)) that corresponds to an angle (θn) of the nth light blocking section, and the pitch (Pn) of the light blocking section satisfy a predetermined formula, and the width (Wn) of the light blocking section of the optical pattern changes with function of the pitch (Pn) of the light blocking section. The pitch (Pn) and the width (Wn) of the nth light blocking unit (6a) are preferably in inverse proportional relationship. The optical encoder having higher accuracy and higher resolution compared with the conventional optical encoders is achieved with such configuration.

NOGUCHI TAKUYA (JP)
NAKAJIMA HAJIME (JP)
MUSHA TAKESHI (JP)
TATEI YOSHINAO (JP)
HIRAI TAKASHI (JP)

PCT/JP2011/077630

August 30, 2012

November 30, 2011

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MITSUBISHI ELECTRIC CORP (JP)
NOGUCHI TAKUYA (JP)
NAKAJIMA HAJIME (JP)
MUSHA TAKESHI (JP)
TATEI YOSHINAO (JP)
HIRAI TAKASHI (JP)

G01D5/347

JPH09250933A	1997-09-22
JPH0861990A	1996-03-08

TANAKA, Mitsuo et al. (JP)
Mitsuo Tanaka (JP)

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