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US 12,411,005 B2Granted
Optical encoding system with reduced total harmonic distortion
AssigneePixart Imaging Inc.
InventorsMeng-Yee Lim, Priscilla Tze-Wei Goh, Kuan-Choong Shim, Gim-Eng Chew
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Abstract
There is provided an optical encoding system including a photodiode array and a code disk opposite to each other. The code disk is arranged with multiple code slits at a ring area corresponding to the photodiode array. A length direction of each photodiode of the photodiode array has at least one deviation angle with respect to a length direction of the multiple code slits to reduce the total harmonic distortion in photocurrents.
Claims19
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.
3 more elements
An optical encoding system, comprising:
- a code disk, arranged with equally-spaced multiple code slits along a tangential direction, and the multiple code slits having a first length direction and a second length direction, wherein the first length direction has a first slant angle with respect to a radial direction of the code disk, and the second length direction has a second slant angle with respect to the 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.
3 more elements
An optical encoding system, comprising:
- a photodiode array, comprising multiple sets of photodiodes each set having a first photodiode, a second photodiode, a third photodiode and a fourth photodiode arranged along a first direction,
- wherein a first part and a second part of the first photodiode, the second photodiode, the third photodiode and the fourth photodiode are slanted toward the first direction, and
- the first part and the second part are directly jointed at a connection point which forms an inflection point of the first photodiode, the second photodiode, the third photodiode and the fourth photodiode.
Dependencies are inferred from the claim text.