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US 11,237,024 B2Granted
Optical encoder with covered photo diode
AssigneePixart Imaging Inc.
InventorsKuan-Choong Shim, Gim-Eng Chew
Life of this patent
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Abstract
There is provided an optical encoder including a photodiode array and a code disk opposite to each other. The photodiode array includes at least three sets of position photodiodes and two index photodiodes arranged transversally. The two index photodiodes are adjacently arranged at the same side of the at least three sets of position photodiodes. A first set of position photodiodes and a last set of position photodiodes of the at least three sets of position photodiodes are partially covered to alleviate the total harmonic distortion. The rest position photodiodes of the at least three sets of position photodiodes other than the first and last sets of position photodiodes are not covered.
Claims17
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 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;
- and
- an opaque layer covering upon the first set of position photodiodes and the last set of position photodiodes, wherein
- a coverage of the first photodiode, the second photodiode, the third photodiode and the fourth photodiode of the first set of position photodiodes by the opaque layer is sequentially decreased, and
- a coverage of the first photodiode, the second photodiode, the third photodiode and the fourth photodiode of the last set of position photodiodes by the opaque layer is sequentially increased, 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.
6 more elements
An optical encoder, comprising:
- a photodiode array, comprising at least three sets of position photodiodes arranged adjacently to one another along a first direction, and 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;
- a first index photodiode adjacently arranged at one of two ends of the at least three sets of position photodiodes along the first direction;
- a second index photodiode arranged adjacent to the first index photodiode in the first direction;
- and
- an opaque layer partially covering upon the second index photodiode and extending from one of two edges in the first direction to a center thereof, wherein
- the first photodiode, the second photodiode, the third photodiode and the fourth photodiode of the at least three sets of position photodiodes have a first width along the first direction, and have a same height along a second direction perpendicular to the first direction;
- and
- a second width of each of the first and second index photodiodes along the first direction is larger than or equal to 4 times of the first width.
5 more elements
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 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;
- a first index photodiode adjacently arranged at one of the two ends of the at least three sets of position photodiodes along the first direction;
- a second index photodiode arranged adjacent to the first index photodiode in the first direction;
- and
- an opaque layer covering upon the first set of position photodiodes and the last set of position photodiodes, and partially covering upon the second index photodiode and extending from one of two edges in the first direction to a center thereof, wherein
- a coverage of the first photodiode, the second photodiode, the third photodiode and the fourth photodiode of the first set of position photodiodes by the opaque layer is sequentially decreased, and
- a coverage of the first photodiode, the second photodiode, the third photodiode and the fourth photodiode of the last set of position photodiodes by the opaque layer is sequentially increased, 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.
8 more elements
An optical encoder, comprising:
- a photodiode array, comprising a first set of photodiodes, a second set of photodiodes and a third set of photodiodes arranged adjacently to one another along a first direction, each set of photodiodes having a first photodiode, a second photodiode, a third photodiode and a fourth photodiode arranged along the first direction;
- and
- an opaque layer covering upon the first set of photodiodes and the third set of photodiodes, wherein
- a coverage of the first set of photodiodes by the opaque layer is sequentially decreased along the first direction, and
- a coverage of the third set of photodiodes by the opaque layer is sequentially increased along the first 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.
6 more elements
Dependencies are inferred from the claim text.