# US 11,079,223 B2 · Absolute rotary encoder and apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,079,223 B2 - Document ID: US11079223B2 - Status: Granted - Kind: B2 - Application number: 16/695,002 - Filed: 2019-11-25 - Published: 2020-06-04 - Granted: 2021-08-03 - Earliest claimed: 2018-12-03 - Assignees: Canon Precision Inc. - Applicants: Canon Precision Inc. - Inventors: Kousuke Kudo; Ryo Sasaki - Web page: https://patentgrep.com/patent/US11079223B2 ## CPC - G01D 5/34792: {with only digital scales or both digital and incremental scales} - G01B 21/045: {Correction of measurements (G01B9/02055 takes precedence)} - G01B 21/20: for measuring contours or curvatures, e.g. determining profile - G01D 5/2053: {by a movable non-ferromagnetic conductive element} - G01D 5/2086: {by movement of two or more coils with respect to two or more other coils} - G01D 5/24471: {Error correction} - G01D 5/24476: {Signal processing (G01D5/2448 - G01D5/24495 take precedence)} - G01D 5/2452: {incorporating two or more tracks having an (n, n+1, ...) relationship} - G01D 5/36: Forming the light into pulses - G06F 17/17: Function evaluation by approximation methods, e.g. inter- or extrapolation, smoothing, least mean square method ({G06F17/18 takes precedence } ; interpolation for numerical control G05B19/18) - G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract An encoder comprises first and second sensors which reads first and second tracks, the first and second sensors being arranged in a radial direction to face each other, and a processor which generates a first position signal based on first and second periodic signals based on a signal obtained by reading the first and second tracks by the first sensor, and generates a second position signal based on third and fourth periodic signals based on a signal obtained by reading the first and second tracks by the second sensor, wherein the processor generates an absolute position signal indicating an absolute position of at least one of the scale, the first sensor, or the second sensor based on the first and second position signals and the first and third periodic signals. ## Claims ### Claim 1 An absolute rotary encoder comprising: a scale on which a first track and a second track are provided with different diameters from each other; a first sensor configured to move relative to the scale and read the first track and the second track; a second sensor arranged so as to face the first sensor in a radial direction of the scale and configured to move relative to the scale and read the first track and the second track; and a processor configured to generate a first position signal by taking a difference between a first periodic signal based on a signal obtained by reading the first track by the first sensor and a second periodic signal based on a signal obtained by reading the second track by the first sensor, and generates a second position signal by taking a difference between a third periodic signal based on a signal obtained by reading the first track by the second sensor and a fourth periodic signal based on a signal obtained by reading the second track by the second sensor, wherein the processor averages the first position signal and the second position signal to generate a third position signal, combines the third position signal and the first periodic signal to generate a fourth position signal, combines the third position signal and the third periodic signal to generate a fifth position signal, and averages the fourth position signal and the fifth position signal to generate an absolute position signal indicating an absolute position of at least one of the scale, the first sensor, or the second sensor. ### Claim 2 (depends on 1) The absolute rotary encoder according to claim 1, wherein the processor includes a first processor configured to generate the first position signal and the absolute position signal and a second processor configured to generate the second position signal. ### Claim 3 (depends on 1) The absolute rotary encoder according to claim 1, wherein the processor includes a first processor configured to generate the first position signal, a second processor configured to generate the second position signal, and a third processor configured to generate the absolute position signal. ### Claim 4 (depends on 1) The absolute rotary encoder according to claim 1, wherein the processor generates the first position signal by taking a difference between the first periodic signal multiplied by an integer and the second periodic signal multiplied by an integer, and generates the second position signal by taking a difference between the third periodic signal multiplied by an integer and the fourth periodic signal multiplied by an integer. ### Claim 5 (depends on 1) The absolute rotary encoder according to claim 1, wherein the first track includes a first periodic pattern and a second periodic pattern which have different periods from each other, the second track includes a third periodic pattern having a period different from those of the first and second periodic patterns and a fourth periodic pattern having a period different from those of the first to third periodic patterns, and the processor generates the first periodic signal by processing a signal corresponding to each of the first and second periodic patterns and the second periodic signal by processing a signal corresponding to each of the third and fourth periodic patterns. ### Claim 6 (depends on 1) The absolute rotary encoder according to claim 1, wherein each of the first sensor and the second sensor includes detectors having different detection cycles. ### Claim 7 (depends on 1) The absolute rotary encoder according to claim 1, wherein each of the first sensor and the second sensor includes detectors which are capable of switching a detection cycle. ### Claim 8 (depends on 1) The absolute rotary encoder according to claim 1, wherein an opposing arrangement angle between the first sensor and the second sensor is set within a range in which a rounding error indicating a reliability of the absolute position does not exceed a threshold. ### Claim 9 (depends on 8) The absolute rotary encoder according to claim 8, wherein the threshold is 0.4. ### Claim 10 An apparatus comprising: a movable member configured to rotate; and an absolute rotary encoder configured to detect a rotation position of the movable member, wherein the absolute rotary encoder comprising: a scale on which a first track and a second track are provided with different diameters from each other; a first sensor configured to move relative to the scale and read the first track and the second track; a second sensor arranged so as to face the first sensor in a radial direction of the scale and configured to move relative to the scale and read the first track and the second track; and a processor configured to generate a first position signal by taking a difference between a first periodic signal based on a signal obtained by reading the first track by the first sensor and a second periodic signal based on a signal obtained by reading the second track by the first sensor, and generates a second position signal by taking a difference between a third periodic signal based on a signal obtained by reading the first track by the second sensor and a fourth periodic signal based on a signal obtained by reading the second track by the second sensor, wherein the processor averages the first position signal and the second position signal to generate a third position signal, combines the third position signal and the first periodic signal to generate a fourth position signal, combines the third position signal and the third periodic signal to generate a fifth position signal, and averages the fourth position signal and the fifth position signal to generate an absolute position signal indicating an absolute position of at least one of the scale, the first sensor, or the second sensor.