Optical encoding system compensating assembly tolerance
AssigneePixart Imaging Inc.
InventorsKuan-Choong Shim, Meng-Yee Lim, Priscilla Tze-Wei Goh, 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 photodiode array includes a detection photodiode group and a calibration photodiode group. If there is a position deviation between the photodiode array and the code disk, whether to utilize detection signals of the calibration photodiode group is determined according to phase shifts between detection signals outputted by the detection photodiode group so as to eliminate the phase shifts.
Claims20
An optical encoding system, comprising:
- a code disk, arranged with equally-spaced multiple code slits along a tangential direction;
- a photodiode array, comprising multiple groups of detection photodiodes and two groups of calibration photodiodes respectively at two sides of the multiple groups of detection photodiodes in the tangential direction, wherein the multiple groups of detection photodiodes are respectively configured to receive modulated light from the multiple code slits to generate a detection signal as absolute position signals;
- and
- multiple switching devices, configured to switch the multiple groups of detection photodiodes to output multiple detection signals in a first detection, and to switch the two groups of calibration photodiodes to output other detection signals according to phase shifts between the multiple detection signals in the first detection.
An optical encoding system, comprising:
- a first photodiode array, having a first width in a first direction, and configured to generate multiple detection signals as absolute position signals;
- a second photodiode array, having a second width in the first direction, and arranged at a first side of the first photodiode array in a second direction perpendicular to the first direction, wherein the second width is smaller than the first width;
- and
- a third photodiode array, having a third width in the first direction, and arranged at a second side of the first photodiode array in the second direction, wherein the third width is larger than the first width,
- wherein in a first detection the first photodiode array is configured to output the multiple detection signals, and in a second detection the second photodiode array or the third photodiode array is configured to output other detection signals according to phase shifts between the multiple detection signals in the first detection.
An optical encoding system, comprising:
- a code disk, arranged with equally-spaced multiple code slits along a tangential direction;
- multiple detection photodiodes, configured to respectively receive modulated light from the multiple code slits to generate a detection signal as absolute position signals;
- multiple calibration photodiodes;
- and
- multiple switching devices, configured to switch the multiple calibration photodiodes to output other detection signals according to phase shifts between multiple detection signals generated by the multiple detection photodiodes.
Dependencies are inferred from the claim text.