US 11,709,077 B2
Optical encoder with covered photo diode
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 Dec. 8, 2021, as Appl. No. 17/545,116.
Application 17/545,116 is a continuation of application No. 16/583,972, filed on Sep. 26, 2019, granted, now 11,237,024.
Claims priority of provisional application 62/742,498, filed on Oct. 8, 2018.
Prior Publication US 2022/0099464 A1, Mar. 31, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. G01D 5/347 (2006.01)
CPC G01D 5/3473 (2013.01) [G01D 5/34707 (2013.01)] 13 Claims
OG exemplary drawing
 
1. An optical encoder, comprising:
a photodiode array, comprising at least three sets of position photodiodes arranged adjacently to one another along a first direction, each set of position photodiodes having a first photodiode, a second photodiode, a third photodiode and a fourth photodiode arranged sequentially along the first direction and each of the first, second, third and fourth photodiodes having a first width along the first direction, and the at least three sets of position photodiodes comprising a first set of position photodiodes and a last set of position photodiodes respectively at two ends of the at least three sets of position photodiodes, wherein the photodiode array further comprises two index photodiodes arranged adjacent to the first set of position photodiodes or the last set of position photodiodes, and each of the two index photodiodes has a second width, larger than the first width, along the first direction, wherein
the first photodiode, the second photodiode, the third photodiode and the fourth photodiode of the first set of position photodiodes are blocked from receiving light with sequentially decreased area in the first direction, and
the first photodiode, the second photodiode, the third photodiode and the fourth photodiode of the last set of position photodiodes are blocked from receiving light with sequentially increased area in the first direction.