Method for optical code pattern enhancement and generation
First Claim
1. A method of making a position sensor, the sensor including a movable encoder having a track extending along a dimension of the encoder, the track having an optical property that varies with position along said dimension, the sensor further including means for directing an optical input beam onto the track at a selected position along said dimension such that the encoder responds to the input beam by producing a modulated beam having an intensity that is a function of the optical property at the selected position, whereby the intensity of the modulated beam encodes the position of the encoder along said dimension, the method comprising:
- (a) determining the intensity of the modulated beam with the encoder at the selected position, and producing a corresponding measurement signal;
(b) comparing said measurement signal to a predetermined target value for the selected position;
(c) if the difference between the measurement signal and the target value exceeds a predetermined tolerance, modifying the optical property at said position; and
(d) repeating steps (a)-(c) until said difference is within said tolerance.
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Accused Products
Abstract
A technique for trimming or making a position sensor that includes a movable encoder having a track extending along a dimension of the encoder, the track having an optical property that varies with position. The sensor also includes a light source for directing an optical input beam onto the track, such that the encoder responds by producing a modulated beam having an intensity that is a function of the optical property. The intensity of the modulated beam thereby encodes the position of the encoder. The technique of the invention comprises the steps of determining the intensity of the modulated beam with the encoder at a selected position, producing a corresponding measurement signal, and comparing the measurement signal to a predetermined target value. If the difference between the measurement signal and the target value exceeds a tolerance, the optical property at the position is modified, for example using a laser beam to ablate a portion of the track. The determining, comparing, and modifying steps are repeated one or more times for each of a plurality of positions, until all differences are within tolerance. The laser beam may be directed onto the track through an access port from a position external to the encoder, such that the encoder can be trimmed after it is fully assembled.
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Citations
22 Claims
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1. A method of making a position sensor, the sensor including a movable encoder having a track extending along a dimension of the encoder, the track having an optical property that varies with position along said dimension, the sensor further including means for directing an optical input beam onto the track at a selected position along said dimension such that the encoder responds to the input beam by producing a modulated beam having an intensity that is a function of the optical property at the selected position, whereby the intensity of the modulated beam encodes the position of the encoder along said dimension, the method comprising:
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(a) determining the intensity of the modulated beam with the encoder at the selected position, and producing a corresponding measurement signal; (b) comparing said measurement signal to a predetermined target value for the selected position; (c) if the difference between the measurement signal and the target value exceeds a predetermined tolerance, modifying the optical property at said position; and (d) repeating steps (a)-(c) until said difference is within said tolerance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An apparatus for trimming a sensor, the sensor including a movable encoder having a track extending along a dimension of the encoder, the track having an optical property that varies with position along said dimension, the sensor further comprising means for directing an optical input beam onto the track at a selected position along said dimension such that the encoder responds to the input beam by producing a modulated beam having an intensity that is a function of the optical property at the selected position, whereby the intensity of the modulated beam encodes the position of the encoder along said dimension, the encoder further comprising an acces port through which a light beam may be directed onto the track from a position external to the encoder, and a detection system for determining the intensity of the modulated beam with the encoder at the selected position and producing a corresponding measurement signal, the apparatus comprising:
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(a) means for measuring the encoder position along said dimension and producing a corresponding position signal; (b) error detection means connected to receive the position signal and the measurement signal, and including means for producing an error signal corresponding to the difference between the measurement signal and a target value for the selected position; and (c) a laser system including means for producing a laser beam and for directing the laser beam through the access port onto the track when the selected position is adjacent to the access port, such that the laser beam modifies the optical property at said position. - View Dependent Claims (18, 19, 20, 21)
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22. A sensor, comprising:
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a frame; an encoder movably mounted within the frame, the encoder having a track extending along a dimension of the encoder, the track having an optical property that varies with position along said dimension; means for directing an optical input beam onto the track at a selected position along said dimension, such that the encoded responds to the input beam by producing a modulated beam having an intensity that is a function of the optical property at the selected position, whereby the intensity of the modulated beam encodes the position of the encoder along said dimension; a detection system for determining the intensity of the modulated beam and producing a corresponding measurement signal; and an access port through which a light beam may be directed onto the track from a position external to the frame, whereby the optical property at the selected position can be modified by directing a laser beam through the access port onto the track.
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Specification