US 12,411,005 B2
Optical encoding system with reduced total harmonic distortion
Meng-Yee Lim, Penang (MY); Priscilla Tze-Wei Goh, Penang (MY); Kuan-Choong Shim, Penang (MY); and Gim-Eng Chew, Penang (MY)
Assigned to PIXART IMAGING INC., Hsin-Chu County (TW)
Filed by PIXART IMAGING INC., Hsin-Chu County (TW)
Filed on Oct. 21, 2022, as Appl. No. 17/970,566.
Prior Publication US 2024/0133680 A1, Apr. 25, 2024
Prior Publication US 2024/0230321 A9, Jul. 11, 2024
Int. Cl. G01B 11/26 (2006.01); G01D 5/26 (2006.01)
CPC G01B 11/26 (2013.01) [G01D 5/264 (2013.01)] 19 Claims
OG exemplary drawing
 
1. An optical encoding system, comprising:
a code disk, arranged with equally-spaced multiple code slits along a tangential direction, and a length direction of the multiple code slits having a slant angle with respect to a radial direction of the code disk; and
a photodiode array opposite to the multiple code slits, the photodiode array comprising multiple sets of photodiodes each set having a first photodiode, a second photodiode, a third photodiode and a fourth photodiode sequentially arranged along the tangential direction, wherein
output currents of the first photodiode and the second photodiode are phase quadrature,
output currents of the first photodiode and the third photodiode are out of phase, and
output currents of the second photodiode and the fourth photodiode are out of phase.