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US 9,354,089 B2Granted
Encoder
AssigneeCanon Kabushiki Kaisha
InventorChihiro Nagura
Life of this patent
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Abstract
An encoder includes a scale, a detector array that includes a plurality of detectors, and a signal processor configured to process and convert into positional information, an output signal from the detector array. The signal processor includes a first phase acquirer configured to acquire a first phase of a first modulation period from an output signal of the detector array. The encoder further includes a weighting unit configured to weight an output signal from each of a plurality of detectors using a weight in accordance with a position of the detector array. The weight is set so that in a predetermined range that contains a spatial frequency corresponding to the second modulation period in a spatial frequency response of the first phase acquirer, a value weighted by the weighting unit is equal to or smaller than a non-weighted value.
Claims13
An encoder comprising:
- a scale that includes a pattern row that has a plurality of patterns configured to spatially modulate an energy distribution;
- a detector array that includes plural detectors that are configured to detect the energy distribution from the pattern row and arranged in a moving direction, the detector array being configured to move relatively to the scale;
- and
- a signal processor configured to process and convert into positional information, an output signal from the detector array,
- wherein the pattern row has a first modulation period and a second modulation period different from the first modulation period in the moving direction, and
- wherein the signal processor includes a first phase acquirer configured to acquire a first phase of the first modulation period based on the output signal of the detector array,
- wherein the encoder further comprises a weighting unit configured to weight an output signal from each of the plural detectors using, for each of the plural detectors, a respective weight that is determined in accordance with a position of the each of the plural detectors, and
- wherein, for each of the plural detectors, the respective weight is set so that, in a predetermined range that contains a spatial frequency corresponding to the second modulation period, a value of a spatial frequency response of the first phase acquirer when the output signal from each of the plural detectors is weighted by the weighting unit is smaller than that when the output signal from each of the plural detectors is not weighted by the weighting unit.
5 more elements
A position detecting apparatus comprising:
- a movable unit;
- and
- an encoder configured to detect a position of the movable unit,
- wherein the encoder includes:
- a scale that includes a pattern row that has a plurality of patterns configured to spatially modulate an energy distribution;
- a detector array that includes plural detectors that are configured to detect the energy distribution from the pattern row and arranged in a moving direction, the detector array being configured to move relatively to the scale;
- and
- a signal processor configured to process and convert into positional information, an output signal from the detector array,
- wherein the pattern row has a first modulation period and a second modulation period different from the first modulation period in the moving direction, and
- wherein the signal processor includes a first phase acquirer configured to acquire a first phase of the first modulation period based on the output signal of the detector array,
- wherein the encoder further comprises a weighting unit configured to weight an output signal from each of the plural detectors using, for each of the plural detectors, a respective weight in accordance with a position of the each of the plural detectors, and
- wherein, for each of the plural detectors, the respective weight is set so that, in a predetermined range that contains a spatial frequency corresponding to the second modulation period, a value of a spatial frequency response of the first phase acquirer when the output signal from each of the plural detectors is weighted by the weighting unit is smaller than that when the output signal from each of the plural detectors is not weighted by the weighting unit.
9 more elements
An encoder comprising:
- a scale that includes a pattern row that has a plurality of patterns configured to spatially modulate an energy distribution;
- a detector array that includes plural detectors that are configured to detect the energy distribution from the pattern row and arranged in a moving direction, the detector array being configured to move relatively to the scale, the detector array including a center portion and end portions, the center portion including a plurality of groups of detectors, each group of detectors being for a single phase, each group of detectors including a first number of detectors disposed consecutively, the end portions each including a second number of detectors for each phase, the second number being greater than or equal to one, and less than the first number;
- a signal processor configured to process and convert into positional information, the output signal from the detector array,
- wherein the pattern row has a first modulation period and a second modulation period different from the first modulation period in the moving direction, and
- wherein the signal processor includes a first phase acquirer configured to acquire a first phase of the first modulation period based on a sum of signals from the first number of detectors and a sum of signals from the second number of detectors.
2 more elements
A position detecting apparatus comprising:
- a movable unit;
- and
- an encoder configured to detect a position of the movable unit,
- wherein the encoder includes:
- a scale that includes a pattern row that has a plurality of patterns configured to spatially modulate an energy distribution;
- a detector array that includes plural detectors that are configured to detect the energy distribution from the pattern row and arranged in a moving direction, the detector array being configured to move relatively to the scale, the detector array including a center portion and end portions, the center portion including a plurality of groups of detectors, each group of detectors being for a single phase, each group of detectors including a first number of detectors disposed consecutively, the end portions each including a second number of detectors for each phase, the second number being greater than or equal to one, and less than the first number;
- a signal processor configured to process and convert into positional information, the output signal from the detector array,
- wherein the pattern row has a first modulation period and a second modulation period different from the first modulation period in the moving direction, and
- wherein the signal processor includes a first phase acquirer configured to acquire a first phase of the first modulation period based on a sum of signals from the first number of detectors and a sum of signals from the second number of detectors.
6 more elements
Dependencies are inferred from the claim text.