US 11,808,612 B2
Optical rotary encoder, servo motor, and actuator
Shintaro Ueno, Azumino (JP); Yoshinori Shibahara, Azumino (JP); and Sadaharu Kanamori, Azumino (JP)
Assigned to Harmonic Drive Systems Inc., Tokyo (JP)
Appl. No. 17/298,974
Filed by HARMONIC DRIVE SYSTEMS INC., Tokyo (JP)
PCT Filed Mar. 15, 2019, PCT No. PCT/JP2019/011012
§ 371(c)(1), (2) Date Jun. 2, 2021,
PCT Pub. No. WO2020/188668, PCT Pub. Date Sep. 24, 2020.
Prior Publication US 2022/0065667 A1, Mar. 3, 2022
Int. Cl. G01B 11/26 (2006.01); G01D 5/347 (2006.01); H02K 1/22 (2006.01)
CPC G01D 5/3473 (2013.01) [H02K 1/22 (2013.01)] 6 Claims
OG exemplary drawing
 
1. An optical rotary encoder comprising:
a rotating disc provided with a plurality of detection tracks that are formed concentrically;
a light-emitting element that irradiates the detection tracks with detection light;
a fixed slit plate provided with a slit pattern that allows passage of optical signals obtained from regions irradiated with the detection light in each of the detection tracks; and
a light-receiving element that receives each of the optical signals that have passed through the slit pattern,
wherein each of the detection tracks is configured from a slit or a reflective zone arranged at regular angular intervals;
the slit pattern in the fixed slit plate is configured from slit rows, the number of slit rows corresponding to the number of detection tracks;
the slit rows includes a plurality of first slit rows and a plurality of second slit rows, the first and second slit rows being lined up in the radial direction of the rotating disc;
the first slit rows have a slit-arrangement-direction length that is shorter than that of the second slit rows; and
the slit pattern is formed so that each of the first slit rows is positioned on both radial-direction sides, the radial direction being a direction in which the slit rows are lined up, and the slit pattern being positioned within an effective irradiation region of the detection light in the fixed slit plate.