US 11,994,416 B2
Signal processing circuit of anti-pollution optical encoder
Kuan-Choong Shim, Penang (MY); Gim-Eng Chew, Penang (MY); Priscilla Tze-Wei Goh, Penang (MY); and Meng-Yee Lim, Penang (MY)
Assigned to PIXART IMAGING INC., Hsin-Chu County (TW)
Filed by PixArt Imaging Inc., Hsin-Chu County (TW)
Filed on Jul. 10, 2023, as Appl. No. 18/219,729.
Application 18/219,729 is a division of application No. 17/104,822, filed on Nov. 25, 2020, granted, now 11,740,108.
Prior Publication US 2023/0349732 A1, Nov. 2, 2023
Int. Cl. G01D 5/34 (2006.01); G01D 5/347 (2006.01)
CPC G01D 5/3473 (2013.01) 10 Claims
OG exemplary drawing
 
1. A signal processing circuit of an optical encoder, the optical encoder comprising a first index photodiode, a second index photodiode and a reference index photodiode, the signal processing circuit comprising:
a trans-impedance amplifier (TIA), electrically coupled to the first index photodiode, the second index photodiode and the reference index photodiode, and configured to convert a first photocurrent generated by the first index photodiode, a second photocurrent generated by the second index photodiode and a reference photocurrent generated by the reference index photodiode respectively to a first voltage, a second voltage and a reference voltage;
a first comparator, configured to compare the first voltage and the reference voltage to output a first comparison voltage;
a second comparator, configured to compare the second voltage and the reference voltage to output a second comparison voltage; and
an AND gate, configured to receive the first comparison voltage and the second comparison voltage to accordingly generate an index output.