[go: up one dir, main page]

US20100057392A1 - Indexed optical encoder, method for indexing an optical encoder, and method for dynamically adjusting gain and offset in an optical encoder - Google Patents

Indexed optical encoder, method for indexing an optical encoder, and method for dynamically adjusting gain and offset in an optical encoder Download PDF

Info

Publication number
US20100057392A1
US20100057392A1 US12/549,731 US54973109A US2010057392A1 US 20100057392 A1 US20100057392 A1 US 20100057392A1 US 54973109 A US54973109 A US 54973109A US 2010057392 A1 US2010057392 A1 US 2010057392A1
Authority
US
United States
Prior art keywords
index
track
offset
reflective
encoder disk
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US12/549,731
Other languages
English (en)
Inventor
Frederick York
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Faro Technologies Inc
Original Assignee
Faro Technologies Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Faro Technologies Inc filed Critical Faro Technologies Inc
Priority to US12/549,731 priority Critical patent/US20100057392A1/en
Assigned to FARO TECHNOLOGIES, INC. reassignment FARO TECHNOLOGIES, INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: YORK, FREDERICK
Publication of US20100057392A1 publication Critical patent/US20100057392A1/en
Priority to US13/656,078 priority patent/US8513589B2/en
Priority to US13/656,110 priority patent/US8476579B2/en
Priority to US13/948,961 priority patent/US20130306850A1/en
Abandoned legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • 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
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/347—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells using displacement encoding scales
    • G01D5/34707—Scales; Discs, e.g. fixation, fabrication, compensation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • 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
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • 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
    • G01D18/00—Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • 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
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/244—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing characteristics of pulses or pulse trains; generating pulses or pulse trains
    • G01D5/24471—Error correction
    • G01D5/24476—Signal processing
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • 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
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/244—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing characteristics of pulses or pulse trains; generating pulses or pulse trains
    • G01D5/245—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing characteristics of pulses or pulse trains; generating pulses or pulse trains using a variable number of pulses in a train
    • G01D5/2454—Encoders incorporating incremental and absolute signals
    • G01D5/2455—Encoders incorporating incremental and absolute signals with incremental and absolute tracks on the same encoder
    • G01D5/2457—Incremental encoders having reference marks
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • 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
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • 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
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/347—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells using displacement encoding scales
    • G01D5/3473—Circular or rotary encoders
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • 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
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/36—Forming the light into pulses
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • 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
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/36—Forming the light into pulses
    • G01D5/38—Forming the light into pulses by diffraction gratings
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
    • G06F17/10—Complex mathematical operations
    • G06F17/18—Complex mathematical operations for evaluating statistical data, e.g. average values, frequency distributions, probability functions, regression analysis

Definitions

  • U.S. Pat. No. 5,355,220 to Kobayashi et al. discloses a light from a source radiated onto a diffraction grating to generate diffracted lights of different orders of diffraction permitting detection of light and dark stripes. Movement is measured by direct detection of movement of the stripes.
  • U.S. Pat. No. 5,486,923 to Mitchell et al. discloses a grating which concentrates light having a pre-selected wavelength into + and ⁇ first orders while minimizing the zero order.
  • the diffracted orders of light illuminate a polyphase detector plate.
  • U.S. Pat. No. 5,559,600 to Mitchell et al. discloses a grating concentrating a pre-selected wavelength into positive and negative first orders.
  • a polyphase periodic detector has its sensing plane spaced from the scale at a location where each detector element responds to the positive and negative first orders without requiring redirection of the diffracted light.
  • U.S. Pat. No. 5,909,283 to Eselun uses a point source of light directing a beam at an angle onto a movable scale. Diffraction beams are generated which are intersected by an optical component such as a Ronchi grating so as to form Moire fringe bands. An array of sets of photodetectors are positioned to intercept the bands of the Moire pattern and emit signals that are electronically processed to indicate displacement of the scale.
  • U.S. Pat. No. 7,002,137 to Thorburn discloses an optical encoder including a scale, the scale including an optical grating and an optical element; a sensor head, the sensor head including a light source and a detector array both of which are disposed on a substrate, the scale being disposed opposite the sensor head and being disposed for movement relative to the sensor head.
  • a distance between the scale and a Talbot imaging plane closest to the scale being equal to d.
  • the sensor head being disposed within a region bounded by a first plane and a second plane, the first plane being separated from the scale by a distance substantially equal to n times d plus d times x, the second plane being separated from the scale by a distance substantially equal to n times d minus d times x, n being an integer and x being less than or equal to one half.
  • the light source emits a diverging beam of light, the diverging beam of light being directed towards the scale, light from the diverging beam of light being diffracted by the grating towards the detector array.
  • a mask is disposed between the scale and the sensor head, the mask defining an aperture, the mask remaining substantially fixed relative to the sensor head, the aperture being sized and positioned to substantially prevent fifth order beams diffracted from the grating from reaching the detector array.
  • An embodiment of an optical encoder may include an encoder disk, an illumination system structured to direct light to the encoder disk, and a detector structured to detect light diffracted from the encoder disk.
  • the encoder disk may include a signal track comprising a diffraction grating formed as a ring on the encoder disk and an index track comprising a reflective index mark, wherein a width of the index mark is larger than a pitch of the diffraction grating.
  • An embodiment of an encoder disk for use in an optical encoder may include a signal track comprising a diffraction grating formed as a ring on the encoder disk, and an index track comprising a reflective index mark, wherein a width of the index mark is larger than a pitch of the diffraction grating.
  • An embodiment of an indexing method for use with an optical encoder may include providing an encoder disk, providing an illumination system structured to direct light to the encoder disk, providing a detector structured to detect light diffracted from the encoder disk, calculating an estimated state count k est of quadrature states from a rising edge of the index pulse to a middle of the index interval, calculating Q kest , wherein Q kest is the quadrature state at k est and corresponds to the quadrature state at an approximate center of the index pulse, and determining an offset correction.
  • the encoder disk may include a signal track comprising a diffraction grating formed as a ring on the encoder disk, and an index track formed as a ring on the encoder disk, the index track comprising an index mark provided at an index angular coordinate.
  • the detector may include two offset detectors structured to detect light diffracted from the signal track and output a quadrature signal, and an index detector structured to detect light reflected from the index track and output an index pulse.
  • An embodiment of a method of dynamically adjusting gain and offset in an optical encoder may include providing an encoder disk comprising a diffraction grating, illuminating the encoder disk with light, providing a detector structured to detect light diffracted from the diffraction grating and output a first fine count channel, calculating a first target gain and first target offset for the first fine count channel, and applying a correction to data sampled from the first fine count channel based on the first target gain and first target offset.
  • FIG. 1 is a diagram of an embodiment of an encoder disk.
  • FIG. 2 is a diagram showing relative position of the dual quadrature signals and index signal according to at least an embodiment.
  • FIG. 3 is a diagram showing relative position of the dual quadrature signals and index signal according to at least an embodiment.
  • FIG. 4 is a diagram showing relative position of the dual quadrature signals and gated and ungated index signals according to at least an embodiment.
  • FIG. 5A is a diagram of an encoder disk according to at least an embodiment.
  • FIG. 5B is a magnified view of a portion of an encoder disk according to at least an embodiment.
  • FIG. 6 is a diagram of an encoder disk according to at least an embodiment.
  • FIG. 7 is a diagram of a portion of an encoder disk and various detectors according to at least an embodiment.
  • FIG. 8A is a diagram showing the relative position of index tracks and detector according to at least an embodiment.
  • FIG. 8B is a graph showing signals generated by the index tracks according to at least an embodiment.
  • FIG. 9 is a graph showing various signals according to at least an embodiment.
  • FIG. 10 is a diagram of a comparator according to at least an embodiment.
  • FIG. 11 is a diagram showing the different quadrature states according to at least an embodiment.
  • FIG. 12A is a diagram to explain the indexing algorithm according to at least an embodiment.
  • FIG. 12B is a diagram to explain the indexing algorithm according to at least an embodiment.
  • FIG. 13A is a diagram to explain the indexing algorithm according to at least an embodiment.
  • FIG. 13B is a diagram to explain the indexing algorithm according to at least an embodiment.
  • FIG. 13C is a diagram to explain the indexing algorithm according to at least an embodiment.
  • FIG. 14 is a diagram to explain the indexing algorithm according to at least an embodiment.
  • FIG. 15 is a diagram to show light reflection off the encoder disk according to at least an embodiment.
  • FIG. 16 is a chart showing the effect of light reflection on the index signals according to at least an embodiment.
  • FIG. 17 is a photograph of the front of an encoder disk with one side painted black according to at least an embodiment.
  • FIG. 18 is a photograph of the front of an encoder disk with one side painted black according to at least an embodiment.
  • FIG. 19 is a photograph of the back of an encoder disk with one side painted black according to at least an embodiment.
  • FIG. 20 is a graph showing various beam profiles of a multi-mode VCSEL according to at least an embodiment.
  • FIG. 21 is a graph showing the relationship between current and beam profile in a multi-mode VCSEL.
  • FIG. 22 is a diagram showing a diffraction patter for an encoder according to at least an embodiment.
  • FIG. 23 is a three-dimensional graph showing a Gaussian beam profile.
  • FIG. 24 is a display showing a Gaussian beam profile.
  • FIG. 25 is a graph showing a beam profile of a multi-mode VCSEL according to at least an embodiment.
  • FIG. 26 is a graph showing a beam profile of a multi-mode VCSEL according to at least an embodiment.
  • FIG. 27 is a graph showing a beam profile of a multi-mode VCSEL according to at least an embodiment.
  • FIG. 28 is a graph showing a beam profile of a multi-mode VCSEL according to at least an embodiment.
  • FIG. 29 is a diagram showing various beam profiles of a multi-mode VCSEL according to at least an embodiment.
  • FIG. 30 is a graph showing various beam profiles of a multi-mode VCSEL according to at least an embodiment.
  • FIG. 31 is a graph showing various beam profiles of a multi-mode VCSEL according to at least an embodiment.
  • FIG. 32 is a display showing a beam profile of a multi-mode VCSEL according to at least an embodiment.
  • FIG. 33 is a graph showing the relationship between current and beam profile for a multi-mode VCSEL according to at least an embodiment.
  • FIG. 34 is a graph showing a Gaussian beam profile.
  • FIG. 35 is a graph showing a Gaussian beam profile.
  • FIG. 36 is a graph showing a non-Gaussian beam profile of a multi-mode VCSEL according to at least an embodiment.
  • FIG. 37 is a graph showing a non-Gaussian beam profile of a multi-mode VCSEL according to at least an embodiment.
  • FIG. 38 is a diagram of a VCSEL power control circuit according to at least an embodiment.
  • FIG. 39 is a diagram of a VCSEL power control circuit according to at least an embodiment.
  • FIG. 40 is a diagram of a VCSEL.
  • FIGS. 41-42 are views of a two chrome layer encoder disk.
  • FIG. 43 is a Lissajous pattern of outputs of quadrature channels before gain modification.
  • FIG. 44 are graphs showing data regarding read head calibration.
  • FIG. 45 is a Lissajous pattern of outputs of quadrature channels after gain modification.
  • FIG. 46 are graphs showing data regarding read head calibration.
  • FIGS. 47-49 are graphs showing outputs from a two chrome layer encoder disk.
  • FIGS. 50-55 are various views of two chrome layer encoder disks.
  • FIG. 56 is a schematic showing a dynamic parameter adjustment method.
  • FIG. 57 is a flowchart showing a pre-filtering method.
  • FIG. 58 is a diagram showing various windows for a moving average filter.
  • FIG. 59 is a diagram showing the error in a quadrature state for a positive DC offset.
  • FIG. 60 is a diagram showing the error in a quadrature state for a negative DC offset.
  • an encoder disk 10 can be formed by placing a track of lines, such as signal track 12 , along the outer part of a circular piece of glass. When illuminated, the lines of the signal track 12 create an alternating light/dark pattern.
  • the disk count refers to the number of light/dark pairs per disk revolution.
  • Pitch refers to the distance between each mark or line of signal track 12 .
  • first quadrature signal (CH A) 20 and second quadrature signal (CH B) 22 are commonly referred to as first quadrature signal (CH A) 20 and second quadrature signal (CH B) 22 .
  • CH A first quadrature signal
  • CH B second quadrature signal
  • combined pair of signal 20 and signal 22 is commonly referred to as a quadrature signal, with it being understood that a quadrature signal includes a pair of phase-shifted signals.
  • a second mark is typically added to conventional encoder disk 12 to identify a specific (absolute) location on the disk.
  • Index mark 14 is an example of such a mark.
  • FIG. 3 shows an index signal 24 compared to first quadrature signal 20 and second quadrature signal 22 .
  • Quadrature encoders can come in two forms, gated or ungated.
  • FIG. 4 shows examples of different index signals based on different types of gating.
  • gated index signal 26 is gated with the product of the first quadrature signal 20 and the second quadrature signal 22 .
  • Another example is gated index signal 27 , which is gated with only the first quadrature signal.
  • a third possible example is ungated index signal 28 .
  • An index pulse There are two methods for generating an index pulse.
  • a comparator follows the conditioned detector signal and toggles when light intensity is above some threshold.
  • a second method uses diffraction.
  • the index mark is made of a series of fine lines of varying pitch.
  • Two or more photo detectors are placed at different locations dependant on diffraction order. The signals are added (or subtracted) and applied to a comparator. When signal levels are above some threshold an index pulse is generated. Both methods require critical alignment due to the small reflective or diffractive area.
  • FIGS. 5A , 5 B, and 6 show an embodiment of an encoder disk.
  • encoder disk 30 may include a signal track 32 that is a diffraction grating formed as a ring on encoder disk 30 .
  • the signal track may be formed by alternating reflective and non-reflective portions.
  • the non-reflective portions of the signal track may be formed by blackened or darkened glass, such as by painting with a flat black paint or other suitable method.
  • the term non-reflective does not necessarily require a surface to have 0% reflectivity.
  • a non-reflective surface can have a low reflectivity, such as a reflectivity of 5% or another suitable value.
  • FIGS. 41 and 42 illustrate an embodiment of an encoder disk 400 using two layers of chrome.
  • FIG. 41 shows an encoder disk 400 having a substrate 402 , a low reflective chrome layer 404 , and a high reflective chrome layer 406 .
  • High reflective chrome layer 406 is deposited on low reflective chrome layer 404 .
  • High reflective chrome layer 406 may be formed in a pattern such that a portion of a portion of low reflective 404 remains visible after high reflective chrome layer 406 is applied.
  • high reflective chrome layer 406 may be formed in a pattern to form a signal track and index tracks on the encoder disk.
  • the low reflective chrome layer 404 may be made of chrome oxide or another suitable material for example, and may have a reflectivity of 5% on the air side in at least one embodiment. Additionally, in at least one embodiment, the high reflective chrome layer may have a reflectivity of 65% on the air side and 59% on the glass side. The performance of encoders having two chrome layers will be discussed further herein.
  • Encoder disk 30 may also include an outer index track 34 that is positioned outside signal track 34 in a radial direction, i.e., towards the outer edge of encoder disk 30 .
  • outer index track 34 is non-reflective except for a reflective outer index mark 35 positioned at an index angular coordinate of the encoder disk.
  • the index angular coordinate can be an arbitrary “zero” reference point in the circumferential direction.
  • Encoder disk 30 can also include an inner index track 36 formed as a ring on encoder disk 30 .
  • Inner index track can be formed inside the signal track in a radial direction, i.e., closer to the center of encoder disk 30 .
  • inner index track is reflective except for a non-reflective inner index mark 37 positioned at the same index angular coordinate as reflective outer index mark 35 .
  • a width of the index mark is larger than the pitch of the diffraction grating.
  • FIGS. 5B and 6 show a non-reflective outer index track 34 with a reflective outer index mark 35 and a reflective inner index track 36 with a non-reflective inner index mark 37 , it will be understood that the reflective and non-reflective portions can be exchanged and still achieve the exact same results.
  • non-reflective portions of the index tracks can be implemented in a variety of ways.
  • non-reflective portions of the index track can be formed by darkening the glass of the encoder disk.
  • FIGS. 50-55 illustrate specific possible embodiments of encoder disks 400 , 500 having two chrome layers.
  • encoder disks 400 , 500 are structured similarly to the encoder disk described above, and may include an outer index track 434 , 534 ; an outer index mark 435 , 535 ; inner index track 436 , 536 ; and inner index mark 437 , 537 .
  • the reflective and non-reflective portions of encoder disks 400 , 500 can be exchanged and are not limited to one specific arrangement. Additionally, it will be understood that the dimensions indicated in the specific drawings refer to the specific embodiments shown, and do not limit the scope of the invention in any way.
  • Photodetectors can be used to monitor each index track and the signal track. As seen in FIG. 7 , detectors 40 , 41 can be used to detect the outer and inner index tracks, and signal track detector 42 can be used to detect the light diffracted from the signal track. Since the index patterns are the opposite of each other (i.e., one index track is reflective at index angular coordinate and the other index track is non-reflective at the index angular coordinate), then the index outputs from detectors 40 , 41 will be inverted about a common offset level.
  • FIG. 8A shows a view focused on the region of the index angular coordinate.
  • the dark region i.e., 34 , 37
  • the light region i.e., 35 , 36
  • Detectors 40 , 41 are shown superimposed over the index tracks.
  • FIG. 8A uses the same configuration of reflective and non-reflective portions as seen in FIGS. 5B and 6 .
  • FIG. 8B shows the output of the inner index signal 46 and the outer index signal 48 as a function of time.
  • the left of the graph represents a period in time when the index angular coordinate is far from the detectors 40 , 41 .
  • the inner index track is reflective at detector 41 , and thus inner index signal 46 is high to the left of the graph in FIG. 8B .
  • the outer index track is non-reflective at detector 40 , and thus outer index signal 48 is low to the left of the graph in FIG. 8B .
  • FIG. 8A As time progresses and the encoder disk rotates in FIG. 8A , the region seen by detector 40 transitions from non-reflective to reflective, and the region seen by detector 41 transitions from reflective to non-reflective. This transition is reflected in FIG. 8B by the inner index signal 46 going from high to low, and the outer index signal 47 going from low to high. An intersection of inner index signal 46 and outer index signal 47 can indicate the “start” or “end” of the index mark on the encoder disk.
  • FIG. 9 indicates one example of a display showing index pulse and signal track traces.
  • index pulse 80 of FIG. 9 represents the index mark.
  • FIG. 9 further shows that the rise and fall of index pulse 80 corresponds to intersections 44 of inner index signal 46 and outer index signal 48 .
  • FIG. 10 shows one example of a comparator for converting an inner index signal and an outer index signal into a logical index signal.
  • the logical index signal will transition high or low based on the intersections of the inner index signal and outer index signal.
  • a diffraction grating signal track can produce dual quadrature signals such as CH A 20 and CH B 22 . These signals can be created by using a detector 42 that includes offset detectors, for example. The magnitude and direction of rotation can be determined by analyzing the dual quadrature signals, for example through an up/down counter. Once indexed, an absolute position can also be determined from the up/down counter.
  • the quadrature states represent a Gray Code sequence. Entry into a different quadrature state from a previous (different) state will either increment or decrement the position counter based on direction.
  • index marks on the index tracks can be large enough such that progressing through the index track progresses through several quadrature states.
  • the optimum target index state is the quadrature state closest to the center of the index pulse 72 or index interval.
  • the optimum target state is K/2 (for even K) or (K+1)/2 (for odd K).
  • the “optimum” state is identical for CW and CCW rotations when K is odd and different by one quadrature state when K is even (see FIG. 12B , for example). This situation is discussed in more detail below.
  • the index interval 72 can either shift asymmetrically (i.e., in one direction) or symmetrically (i.e., expansion or contraction about the index center point). By superposition one can have a combination of the two, but errors can be accounted for by examining the asymmetrical and symmetrical characteristics individually. Further, application of hysteresis to the trailing edge of the index pulse 72 will reduce the ambiguity to one quadrature state.
  • the first is due to a shift in read head position, and the second source is due to the ambiguity (caused by noise and delay) which provides a simultaneous change of quadrature state and an index pulse transition.
  • a moving read head makes a precision encoder unrealizable. This must be eliminated by design.
  • the second asymmetrical error source has two components. If a single edge occurs, a 1 ⁇ 2 count error (1 ⁇ 2 quadrature state) is realized. The second component, which results in a worst case condition, exists if a transition ambiguity occurs at both ends and in the same direction (Different direction would constitute a symmetrical shift). However, when considering travel in both CCW and CW directions this may translate to a two count (or quadrature state) difference between both estimates. This is undesirable as there is an ambiguity of which state is correct. Hysteresis provides a solution to this source of error.
  • the reference point Given a target state (Q target ), the reference point can be established from four variables. The way in which these variables are used to adjust the reference point is referred to as the Index Algorithm.
  • the Index Algorithm must be run in both directions. The outputs from each pass are evaluated and a Q target selected. This is described later.
  • Q target is established by running the Indexer Algorithm in both directions.
  • the algorithm calculates k target (number of states from index start to target state (Q target )). Note that Q target is the best state (closest to the center of the index interval).
  • P _Count new P _Count current ⁇ [P _Count ⁇ index +( k target ⁇ 1)]. EQ 1.
  • P _Count new P _Count current ⁇ [P _Count ⁇ index ⁇ ( k target ⁇ 1)]. EQ 2.
  • k est K/ 2 (for K even) or ( K+ 1)/2 (for K odd). EQ 3.
  • the Q's are assigned by direction and the second element (See Clarification Note) is addressed by the Index rising edge.
  • the table generated is named the Offset Table. Moving down the Table is positive (increasing counts), up is negative. This is independent of the direction of rotation.
  • Q1 LH Table 1 (Example Offset Table)
  • Q 3 HL [nearest HL to Q 0 ]
  • Q 0 LL
  • Q 2 HH
  • the structure and methods described above have a number of significant advantages. For example, optical alignment becomes very simple. No precision gratings on the encoder scale or placement of the read head is required. Additionally, the gap width (i.e., width of the index mark) is large compared to conventional devices. Therefore, tolerance in gap position can be larger than in conventional encoders. Thus, overall, the structure and methods described above can result in an encoder that is cheaper and simpler to manufacture and implement compared to conventional encoders.
  • the index pulse contains 5 or more quadrature states it is possible to pick a redundant state. This has to be tested for and corrected (usually by hardware, e.g. by cable swap). The structure and technique described above is by design unaffected with this kind of redundant states.
  • multi-mode i.e., non-Gaussian
  • single mode i.e., Gaussian
  • the apparatus is insensitive to beam profiles.
  • An LED can also be used as a possible light source in place of the VCSEL. This flexibility in light sources helps to minimize cost.
  • Multi-mode VCSELS and LEDs can be less expensive and more reliable than single mode diodes, as are simple grating patterns.
  • unwanted reflections from the encoder disk can be reduced by applying an optical black (i.e., light absorbent compound) to the rear surface of the encoder scale.
  • the optical black compound can also be applied to the front of the encoder scale in an alternative embodiment.
  • the low reflective and high reflective layers described above can also reduce unwanted reflections.
  • the method and structure described above uses two complementary (i.e., Boolean interpretation) reflective tracks that are on opposite sides of the quadrature signal grating. Since the index method relies on two reflective paths on each side of the laser beam they must be in line with their respective photo-detectors ( 2 ) and each receive sufficient energy for signal crossover.
  • the Mark channel signal 48 i.e., the signal caused by the reflective outer index mark
  • the Mark signal 48 did not match the Space signal's 46 (i.e., non-reflective inner index mark) lowest level. Because a dip 110 in this DC offset just before the reflection 112 was detected (See FIGS. 15 and 16 ), it was suspected that a reflection from the back surface of the encoder scale was the culprit. Dip 110 is due to a reflection from the back of the encoder scale which is reduced as the Mark reflector comes into view.
  • An optical absorption material applied to the back (or front, outside the grating or Index reflectors), or low reflective and high reflective layers, can improve read head performance. For example, signal to noise ratio for the index signal can be improved, and better quadrature signals can be obtained because of reduced specular reflections.
  • absorptive coating or low reflective and high reflective layers can be optimized for the particular wavelength of light being emitted by the illumination system.
  • FIGS. 17-19 shows a clear region in the center of the encoder disk 30 . This clear region allows UV adhesive to be applied to mount the encoder of this embodiment in a cartridge.
  • FIGS. 43-46 also illustrate calibration data for read heads.
  • FIGS. 43-44 show data before gain modification
  • FIGS. 45-46 show data after gain modification.
  • FIG. 43 shows Lissajous curves 900 , 902 based read head signals.
  • lines 904 , 906 illustrate errors in the read head positions (offset for clarity).
  • Upper line 908 is a plot of the average position of two read heads in the clockwise direction.
  • Lower line 910 is a plot of the average position of the two read heads in a counterclockwise direction.
  • Center line 912 is an average position of the read heads from both directions.
  • FIG. 45 shows Lissajous curves 920 , 922 based on read head signals. In FIG.
  • lines 924 , 926 illustrate errors in the read head positions (offset for clarity).
  • Upper line 928 is a plot of the average position of two read heads in the clockwise direction.
  • Lower line 930 is a plot of the average position of the two read heads in a counterclockwise direction.
  • Center line 932 is an average position of the read heads from both directions.
  • FIGS. 47-49 illustrate outputs from a two chrome layer encoder used in performance testing.
  • line 600 represents a ring with a reflective index mark
  • line 602 represents a ring with a non-reflective index mark
  • line 604 represents a quadrature signal.
  • FIGS. 47-49 show that the dark levels from a non-reflective ring with reflective mark and a reflective ring with a non-reflective mark were below 0.35 VDC, and were matched to within 0.16 VDC of each other. On average, the dark level voltage for the non-reflective ring with reflective mark was measured to be 0.16 VDC and the dark level voltage for the reflective ring with non-reflective mark was measured to be 0.26 VDC.
  • the read head transfer function is attenuated by a factor of 0.8.
  • a gain adjustment can be made to the cartridge boards if necessary.
  • input attenuator resistor values can be changed from 20 k to 13 k.
  • Instrumentation Amplifier Gain can be changed from 2.42 to 3.0 by changing gain resistors from 34.8 k to 24.9 k.
  • the two chrome layer structure on the encoder glass improves the cartridge system in two ways.
  • the device described above can control a multi-mode laser profile via an optical power monitoring scheme.
  • Multi-mode lasers exhibit Gaussian beam profile at low drive current and change into an Laguerre-Gaussian ⁇ 1,0 ⁇ profile (3-D appearance is similar to that of a volcano—with a reduction in optical power toward the center—the “crater”) at higher VCSEL currents (see FIG. 20 , which shows various profiles 300 , 302 , 304 , 306 , 308 of a multi-mode VCSEL). Notice that the beam width increases with VCSEL current when in multi-mode, as seen in FIG. 21 . For example, in FIG. 21 , beam profile 310 is the beam profile at 4 mA current, and beam profile 312 is the beam profile at 6 mA current.
  • the quadrature signals described above are relatively distortion free in either Gaussian or non-Gaussian modes due to the wide spatial collection of energy due to diffraction.
  • VCSELs which are mostly Gaussian (wide beams with a waist of 20 degrees or more the circle quality remains good but the quadrature signals vary linearly and monotonically with VCSEL current.
  • the VCSEL current is adjusted so that narrow beam VCSELs are well into the non-Gaussian region. This avoids a non-monotonic mode which would make the laser power control optical power loop unstable.
  • One method of controlling a laser diode or LED (emitting element) is via a constant current source. This technique minimizes the sensitivity to the forward diode drop due to temperature. In some cases temperature sensing is used to adjust the current and compensate the optical output drift due to temperature.
  • a second method uses optical feedback to compensate.
  • the optical power is measured by a separate photo detector, either within the same package or a separate photo sensor.
  • the present encoder preferably uses the second method but with an additional purpose. Power adjustment of a multimode VCSEL can lead to pronounced changes in beam width and shape. This characteristic is used to optimize the signal to noise ratio due to spatial distortion.
  • Optical encoders use precision rulings on linear or rotary glass scales. These rulings provide a position reference that can be used to measure relative motion between an optical read head and the scale. Often, two quadrature sinusoidal signals are output. Measuring electronics count zero crossings and may also interpolate between zero crossings
  • the present encoder is based on the non-direct imaging technique called Talbot imaging.
  • This type of encoder relies on interference between grating diffraction orders.
  • interference between overlapping diffraction orders produces a pseudo-image that resembles the scale rulings.
  • FIG. 22 depicts the diffraction pattern of the present encoder.
  • the desired information comes from the +1 diffraction band 320 and ⁇ 1 diffraction band 322 .
  • a mask is not used to perform a spatial filtering as in the U.S. Pat No. 7,002,137 to Thorburn. Instead, all of the diffraction orders are passed to the sensor head and then an algorithm filters them electronically.
  • Laser Diodes Single-Mode and Multi-Mode Laser Diodes.
  • FIGS. 25-28 show three-dimensional views of various possible beam profiles 340 , 342 , 344 , and 346 of multi-mode lasers.
  • FIG. 29 shows cross sections 350 - 357 of various possible beam profiles.
  • Multi-mode VCSELs normally generate patterns based on Laguerre-Gaussian (LG) profiles. At low power they provide a Gaussian profile, at higher power levels LG [1,0] are common as seen in FIGS. 30-32 .
  • FIG. 32 shows various views of a beam profile 360 of a multi-mode laser.
  • the present encoder preferably uses an LG [1,0] VCSEL which has a general profile/current transfer function (when in multi-mode) as shown in FIG. 33 .
  • Actual test data can be seen in FIGS. 34-37 .
  • FIGS. 34 and 35 show a beam profile 380 at 2.75 mA.
  • the two lines in FIG. 34 correspond to the profile in the x and y directions.
  • FIGS. 36 and 37 show a beam profile at 4.75 mA.
  • FIG. 38 shows one possible embodiment of VCSEL optical power control circuit 400 . Note that in the embodiment shown in FIG. 38 , resistor R 14 is programmable (i.e., set point control).
  • An encoder can be rotated at a certain frequency (by motor) and a DFT (Discreet Fourier Transform) performed.
  • DFT Discreet Fourier Transform
  • the power control described above helps to compensate for quadrature and index signal drift due to temperature and VCSEL ageing.
  • the VCSEL profile control described above has a number of advantages over conventional profile controls.
  • DSP digital signal processing
  • multi-mode (i.e., non-Gaussian) laser diodes are more reliable than single-mode laser diodes. Construction is more robust as power handling is higher for multi-mode VCSELs. In contrast, single-mode channels are narrow in order to reduce resonances, and they tend to be very sensitive to voltage stress and electrostatic discharge. Also, cost can be minimized by using multi-mode VCSELs, because finer techniques must be employed to produce the pure Gaussian beam profile of a single-mode.
  • FIG. 39 illustrates another possible embodiment of the VCSEL control.
  • VCSEL component D 10 may comprise a metal package, a window (for dust protection), the VCSEL 300 and a photo-detector 302 .
  • a small portion of the laser light is reflected back from the window and excites the photo-detector 302 . Therefore, the amount of optical energy transmitted can be obtained by monitoring the internal photo-detector's current.
  • FIG. 40 shows at least one possible embodiment of a VCSEL 300 .
  • the invention is not limited to this particular VCSEL however, and any other appropriate VCSEL, LED, or other appropriate light source can be used.
  • FIG. 40 also shows a window 301 as part of the VCSEL.
  • the feedback current from the photo-detector 302 is converted into a voltage (V MON ) via resistor R 7 or resistor R 7 in parallel with resistor R 8 .
  • the parallel combination is used when the dynamic range of control is to be increased. Note that resistor RI 7 is normally not mounted, when a zero ohm resistor is mounted in this position the parallel combination can be formed.
  • Op-amp U 1 and transistor Q 1 form a voltage to current converter.
  • V Bias is the set point voltage.
  • Op-amp U 1 amplifies the error between V MON and V Bias .
  • Capacitor C 4 sets the bandwidth.
  • the output voltage (Vout ⁇ U 1 pin 1 ) from op-amp U 1 is applied through resistor R 9 to the base of transistor Q 1 .
  • the emitter current of transistor Q 1 is approximately [Vout ⁇ Vbe]/R 13 , where Vbe is the base emitter voltage of the transistor Q 1 ( ⁇ 0.7 Volts) and R 13 is the resistance of resistor R 13 Note resistor R 9 's effect is negligible due to the fact that the base current is much less than the emitter or collector current by a factor of Beta ( ⁇ 180).
  • Transistor Q 1 's collector current is equal to the VCSEL current and is approximately equal to the emitter current given by the above emitter current equation.
  • V Bias is determined by the reference diode (2.5 V) and the voltage divider formed by resistor R 14 and resistor R 12 .
  • V Bias is normally selected to provide a nominal optical power or VCSEL current.
  • the optical power will remain constant over temperature and component variation (e.g. ageing).
  • multi-mode VCSELs can have an unpredictable beam shape over variations in temperature. This may lead to non-linear amplitude and offset drifts for the quadrature signal used to interpolate position.
  • conventional devices would have significant difficulty in implementing a VCSEL, and it is necessary to implement dynamic adjustment of gain and offset in order for VCSELs to be practical for encoders.
  • FIG. 56 is a schematic to show at least one embodiment of dynamic adjustment of gain and offset.
  • raw data is acquired by a read head at 1000 .
  • this raw data can be parsed into coarse count 1010 , first fine count 1012 , and second fine count 1014 . It will be understood that fine counts 1012 , 1014 represent the two channels of the fine count.
  • the dynamic adjustment has three different process steps: data qualification pre-filtering 1020 , max/min moving average filtering 1030 , and value correction 1040 , 1050 .
  • data qualification pre-filtering 1020 After the data is parsed at 1002 , the fine count is pre-filtered at 1020 .
  • Pre-filtering is used to acquire the three largest and three smallest samples in the data set.
  • threshold levels for the max and min data are used. For example, as 50% threshold or other suitable value can be used.
  • FIG. 57 shows at least one embodiment of a method for acquiring the three largest and three smallest samples in the data set.
  • MaxValue(0), MaxValue(1), MaxValue(2) are the maximum values, with MaxValue(0) being the highest.
  • MinValue(0), MinValue(1), MinValue(2) are the minimum values, with MinValue(0) being the lowest.
  • step 1302 the fine count is compared to MaxValue(0). If fine count is greater than MaxValue(0), then the fine count becomes the new MaxValue(0) and the other members are the array are reordered (see step 1304 ). Otherwise, the fine count is compared to MaxValue(1) at step 1306 . If the fine count is greater than MaxValue(1), then the fine count becomes the new MaxValue(1) and MaxValue(2) is adjusted accordingly (see step 1308 ). Otherwise the fine count is compared to MaxValue(2) at step 1310 . If the fine count is greater than MaxValue(2), then the fine value becomes the new MaxValue(2) (see step 1312 ). If the fine count is less than teach value of the MaxValue array, than the fine count is discarded (see step 1313 ).
  • screening methods can be performed on the data. If the data passes the screening checks, then the highest (maximum) value and the lowest (minimum) value are accepted to use in further calculations. It will be understood that a maximum and minimum value will be found for each fine count 1012 , 1014 . For example, if the screening is satisfied, pre-filtering 1020 will return a first fine count maximum max A , a first fine count minimum, min A , a second fine count maximum max B , a second fine count minimum, min B .
  • the first screening method is to determine whether each of the three highest values are within a predetermined range of their median, and whether each of the three lowest values are within a predetermined range of their median.
  • the predetermined amount may be 1%. Therefore, for the three highest values, the lowest of the three should be greater than or equal to 0.99*the median value, and the highest of the three should be less than or equal to 0.99*the median value. Similarly, for the three lowest values, the highest value should be less than or equal to 0.99*the median value, and the lowest value should be greater than or equal to 1.01*the median value (it will be noted that the three lowest values should be negative).
  • a second screening is performed.
  • the second screening evaluates whether the maximum value and the minimum value are within 10% of the corresponding moving average filter 1030 .
  • This screening assumes that the moving average filter 1030 is completely filled first. For example, in at least one embodiment, the moving average filter 1030 includes five samples. The moving average filter 1030 will be discussed in more detail below. If the maximum and minimum values satisfy the screening, then the maximum and values are incorporated into the corresponding moving average filters and the oldest values are discarded from the tap register.
  • a data capture period is approximately 4 msec (250 Hz rate), and is the local sample rate.
  • the moving average filter 1030 is updated with the newly found minimum and maximum values. It will be understood that there will be a moving average filter for the minimum and maximum values of first fine count 1012 and second fine count 1014 , shown in FIG. 56 as ave_max A , ave_min A , ave_max B , and ave_min B .
  • the moving average filter 1030 is discussed below.
  • x _ k x _ k - 1 + 1 n ⁇ [ x k - x k - n ]
  • a moving average This is known as a moving average because the average at each k'th instant is based on the most recent set of n values.
  • a moving window of n values is used to calculate the average of the data sequence.
  • FIG. 58 there are three windows 1100 , 1102 , and 1103 shown, each consisting of n values.
  • the value of X k is taken as the filtered value of X k .
  • the expression is a recursive one, because the value of X k is calculated using its previous value, X k-1 , as reference.
  • the target values and correction factors can be calculated at 1040 , and then the data values can be corrected at 1050 .
  • the first fine count 1012 values can be corrected in value correction 1050 according to the equation:
  • FC A is the fine count 1012 and CFC A is the corrected fine count for fine count 1012 .
  • first fine count 1012 refers to first fine count 1012 , but it will be readily understand that the same calculations can be performed for second fine count 1014 . Additionally, it will be understand that the same calculations can be formed for first and second fine counts on a plurality of read heads.
  • FIGS. 59-60 illustrate signals 1200 , 1202 that make up a quadrature signal.
  • FIG. 59 shows that if there is a positive DC offset, then high pulses will be erroneously widened, and low pulses will be erroneously shortened. In other words, if a measurement returns a value that is in regions 1204 , it will incorrectly register has a high count instead of a low count. Accordingly, the coarse count of the read head will show the incorrect state.
  • FIG. 60 shows the opposite, i.e., if there is a negative DC offset, high pulses are erroneously narrowed, and low pulses are erroneously widened.
  • a measurement returns a value that is in regions 1206 , it will incorrectly register as a low count instead of a high count. Accordingly, the coarse count of the read head will show the incorrect state.
  • compensated fine counts CFC A calculated above should be symmetrical about ⁇ OFF A
  • compensated fine counts CFC B should be symmetrical about ⁇ OFF B .
  • a corrected state pair ⁇ A′, B′ ⁇ (i.e., a Gray Code value) can be calculated from the corrected fine counts as follows:
  • the corrected state pair can be compared to the uncompensated state pair ⁇ A, B ⁇ indicated by the coarse count, and referencing state—(1, 1) (logically (H,H)).
  • the coarse count can be adjusted by—1, 0, 1 according to the results of this comparison.
  • the corrected coarse and fine counts can be re-assembled and passed to an angle computation module.
  • the gain and offset can be dynamically adjusted, allowing the use of multi-mode VSCEL lasers and simpler grating patterns. Additionally, with this structure and dynamic adjustment method, it is not necessary to spatially filter to eliminate higher order diffraction orders (beyond ⁇ 1), which is required in conventional devices. Instead, the dynamically adjusted parameters account for DC offsets over temperature variations. This is a significant benefit over conventional devices because it results in simpler manufacturing and reduced manufacturing costs.
  • an encoder scale with a diffraction grating can be used, and complementary index tracks (i.e., one with a reflective index mark and one with a non-reflective index mark) can be provided on the encoder scale, being provided either on one side of the diffraction grating, or on either side of the diffraction grating to sandwich the diffraction grating.
  • the index marks can be positioned at a linear index coordinate as opposed to an angular index coordinate.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Data Mining & Analysis (AREA)
  • Signal Processing (AREA)
  • Mathematical Optimization (AREA)
  • Theoretical Computer Science (AREA)
  • Mathematical Physics (AREA)
  • Computational Mathematics (AREA)
  • Pure & Applied Mathematics (AREA)
  • Mathematical Analysis (AREA)
  • Bioinformatics & Cheminformatics (AREA)
  • Operations Research (AREA)
  • Probability & Statistics with Applications (AREA)
  • Evolutionary Biology (AREA)
  • Algebra (AREA)
  • Bioinformatics & Computational Biology (AREA)
  • Databases & Information Systems (AREA)
  • Software Systems (AREA)
  • General Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Optical Transform (AREA)
US12/549,731 2008-08-28 2009-08-28 Indexed optical encoder, method for indexing an optical encoder, and method for dynamically adjusting gain and offset in an optical encoder Abandoned US20100057392A1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US12/549,731 US20100057392A1 (en) 2008-08-28 2009-08-28 Indexed optical encoder, method for indexing an optical encoder, and method for dynamically adjusting gain and offset in an optical encoder
US13/656,078 US8513589B2 (en) 2008-08-28 2012-10-19 Indexed optical encoder, method for indexing an optical encoder, and method for dynamically adjusting gain and offset in an optical encoder
US13/656,110 US8476579B2 (en) 2008-08-28 2012-10-19 Indexed optical encoder, method for indexing an optical encoder, and method for dynamically adjusting gain and offset in an optical encoder
US13/948,961 US20130306850A1 (en) 2008-08-28 2013-07-23 Indexed optical encoder, method for indexing an optical encoder, and method for dynamically adjusting gain and offset in an optical encoder

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US9247808P 2008-08-28 2008-08-28
US22465709P 2009-07-10 2009-07-10
US12/549,731 US20100057392A1 (en) 2008-08-28 2009-08-28 Indexed optical encoder, method for indexing an optical encoder, and method for dynamically adjusting gain and offset in an optical encoder

Related Child Applications (2)

Application Number Title Priority Date Filing Date
US13/656,078 Division US8513589B2 (en) 2008-08-28 2012-10-19 Indexed optical encoder, method for indexing an optical encoder, and method for dynamically adjusting gain and offset in an optical encoder
US13/656,110 Division US8476579B2 (en) 2008-08-28 2012-10-19 Indexed optical encoder, method for indexing an optical encoder, and method for dynamically adjusting gain and offset in an optical encoder

Publications (1)

Publication Number Publication Date
US20100057392A1 true US20100057392A1 (en) 2010-03-04

Family

ID=41571869

Family Applications (4)

Application Number Title Priority Date Filing Date
US12/549,731 Abandoned US20100057392A1 (en) 2008-08-28 2009-08-28 Indexed optical encoder, method for indexing an optical encoder, and method for dynamically adjusting gain and offset in an optical encoder
US13/656,078 Expired - Fee Related US8513589B2 (en) 2008-08-28 2012-10-19 Indexed optical encoder, method for indexing an optical encoder, and method for dynamically adjusting gain and offset in an optical encoder
US13/656,110 Expired - Fee Related US8476579B2 (en) 2008-08-28 2012-10-19 Indexed optical encoder, method for indexing an optical encoder, and method for dynamically adjusting gain and offset in an optical encoder
US13/948,961 Abandoned US20130306850A1 (en) 2008-08-28 2013-07-23 Indexed optical encoder, method for indexing an optical encoder, and method for dynamically adjusting gain and offset in an optical encoder

Family Applications After (3)

Application Number Title Priority Date Filing Date
US13/656,078 Expired - Fee Related US8513589B2 (en) 2008-08-28 2012-10-19 Indexed optical encoder, method for indexing an optical encoder, and method for dynamically adjusting gain and offset in an optical encoder
US13/656,110 Expired - Fee Related US8476579B2 (en) 2008-08-28 2012-10-19 Indexed optical encoder, method for indexing an optical encoder, and method for dynamically adjusting gain and offset in an optical encoder
US13/948,961 Abandoned US20130306850A1 (en) 2008-08-28 2013-07-23 Indexed optical encoder, method for indexing an optical encoder, and method for dynamically adjusting gain and offset in an optical encoder

Country Status (6)

Country Link
US (4) US20100057392A1 (fr)
JP (2) JP5318212B2 (fr)
CN (1) CN102007378B (fr)
DE (1) DE112009002101T5 (fr)
GB (3) GB2496230B (fr)
WO (1) WO2010025365A2 (fr)

Cited By (42)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011085075A2 (fr) 2010-01-07 2011-07-14 Gen9, Inc. Assemblage de polynucléotides haute fidélité
US20110173825A1 (en) * 2010-01-20 2011-07-21 Faro Technologies, Inc. Counter balance for coordinate measurement device
US20110229151A1 (en) * 2010-03-18 2011-09-22 Mitutoyo Corporation Photoelectric encoder
US8284407B2 (en) 2010-01-20 2012-10-09 Faro Technologies, Inc. Coordinate measuring machine having an illuminated probe end and method of operation
US20130105675A1 (en) * 2011-10-28 2013-05-02 Mitutoyo Corporation Displacement detecting device, displacement detecting method, and computer-readable medium
US8476579B2 (en) 2008-08-28 2013-07-02 Faro Technologies, Inc. Indexed optical encoder, method for indexing an optical encoder, and method for dynamically adjusting gain and offset in an optical encoder
US8533967B2 (en) 2010-01-20 2013-09-17 Faro Technologies, Inc. Coordinate measurement machines with removable accessories
US8615893B2 (en) 2010-01-20 2013-12-31 Faro Technologies, Inc. Portable articulated arm coordinate measuring machine having integrated software controls
US8630314B2 (en) 2010-01-11 2014-01-14 Faro Technologies, Inc. Method and apparatus for synchronizing measurements taken by multiple metrology devices
US8638446B2 (en) 2010-01-20 2014-01-28 Faro Technologies, Inc. Laser scanner or laser tracker having a projector
US8677643B2 (en) 2010-01-20 2014-03-25 Faro Technologies, Inc. Coordinate measurement machines with removable accessories
US8832954B2 (en) 2010-01-20 2014-09-16 Faro Technologies, Inc. Coordinate measurement machines with removable accessories
US8875409B2 (en) 2010-01-20 2014-11-04 Faro Technologies, Inc. Coordinate measurement machines with removable accessories
US8898919B2 (en) 2010-01-20 2014-12-02 Faro Technologies, Inc. Coordinate measurement machine with distance meter used to establish frame of reference
US8997362B2 (en) 2012-07-17 2015-04-07 Faro Technologies, Inc. Portable articulated arm coordinate measuring machine with optical communications bus
US9074883B2 (en) 2009-03-25 2015-07-07 Faro Technologies, Inc. Device for optically scanning and measuring an environment
US9113023B2 (en) 2009-11-20 2015-08-18 Faro Technologies, Inc. Three-dimensional scanner with spectroscopic energy detector
US20150292919A1 (en) * 2014-04-14 2015-10-15 Canon Kabushiki Kaisha Absolute encoder, processing method, program, driving apparatus, and industrial machine
US9163922B2 (en) 2010-01-20 2015-10-20 Faro Technologies, Inc. Coordinate measurement machine with distance meter and camera to determine dimensions within camera images
US9168654B2 (en) 2010-11-16 2015-10-27 Faro Technologies, Inc. Coordinate measuring machines with dual layer arm
US9210288B2 (en) 2009-11-20 2015-12-08 Faro Technologies, Inc. Three-dimensional scanner with dichroic beam splitters to capture a variety of signals
US9329271B2 (en) 2010-05-10 2016-05-03 Faro Technologies, Inc. Method for optically scanning and measuring an environment
US9372265B2 (en) 2012-10-05 2016-06-21 Faro Technologies, Inc. Intermediate two-dimensional scanning with a three-dimensional scanner to speed registration
US9417316B2 (en) 2009-11-20 2016-08-16 Faro Technologies, Inc. Device for optically scanning and measuring an environment
US9417056B2 (en) 2012-01-25 2016-08-16 Faro Technologies, Inc. Device for optically scanning and measuring an environment
US20160321810A1 (en) * 2015-04-28 2016-11-03 Pixart Imaging (Penang) Sdn. Bhd. Optical navigation sensor, electronic device with optical navigation function and operation method thereof
US9513107B2 (en) 2012-10-05 2016-12-06 Faro Technologies, Inc. Registration calculation between three-dimensional (3D) scans based on two-dimensional (2D) scan data from a 3D scanner
US9529083B2 (en) 2009-11-20 2016-12-27 Faro Technologies, Inc. Three-dimensional scanner with enhanced spectroscopic energy detector
US9551575B2 (en) 2009-03-25 2017-01-24 Faro Technologies, Inc. Laser scanner having a multi-color light source and real-time color receiver
US9607239B2 (en) 2010-01-20 2017-03-28 Faro Technologies, Inc. Articulated arm coordinate measurement machine having a 2D camera and method of obtaining 3D representations
US9628775B2 (en) 2010-01-20 2017-04-18 Faro Technologies, Inc. Articulated arm coordinate measurement machine having a 2D camera and method of obtaining 3D representations
US20170254670A1 (en) * 2016-03-04 2017-09-07 National Tsing Hua University Absolute position detecting device and method
US10067231B2 (en) 2012-10-05 2018-09-04 Faro Technologies, Inc. Registration calculation of three-dimensional scanner data performed between scans based on measurements by two-dimensional scanner
US10175037B2 (en) 2015-12-27 2019-01-08 Faro Technologies, Inc. 3-D measuring device with battery pack
US10215595B2 (en) 2015-04-22 2019-02-26 Faro Technologies, Inc. Indexed optical encoder
US10281259B2 (en) 2010-01-20 2019-05-07 Faro Technologies, Inc. Articulated arm coordinate measurement machine that uses a 2D camera to determine 3D coordinates of smoothly continuous edge features
US20190271961A1 (en) * 2018-03-01 2019-09-05 Semiconductor Components Industries, Llc Methods and apparatus for an encoder
US11054435B2 (en) 2015-02-24 2021-07-06 Continental Automotiive France Method and device for processing a signal produced by a sensor for detecting the rotation of a rotating target
US20220163353A1 (en) * 2020-11-25 2022-05-26 Pixart Imaging Inc. Anti-pollution optical encoder and signal processing circuit thereof
CN115248054A (zh) * 2021-04-26 2022-10-28 原相科技股份有限公司 可调节索引输出增益的光学式编码器
CN116625281A (zh) * 2022-12-06 2023-08-22 山东林诺威神工控技术有限公司 编码器的偏心位置计算矫正方法
US20250231050A1 (en) * 2024-01-11 2025-07-17 Pixart Imaging Inc. Code wheel and encoding system

Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6069653B2 (ja) * 2011-01-27 2017-02-01 株式会社ミツトヨ 光電式エンコーダ及びそのアライメント調整方法
DE102011075709A1 (de) * 2011-05-12 2012-11-15 Schaeffler Technologies AG & Co. KG Tretlagereinheit für ein Fahrrad
CN104655161B (zh) 2013-11-21 2017-05-10 科沃斯机器人股份有限公司 测距装置及其寻找测距起始点的方法
US10389281B2 (en) * 2016-10-20 2019-08-20 Texas Instruments Incorporated Correcting offset and gain drift related angle errors with motor position detectors
TWI651938B (zh) * 2017-03-06 2019-02-21 曾吉旺 光學掃描式雙層導光編碼器
CN107449460A (zh) * 2017-07-07 2017-12-08 银弗（北京）科技有限公司 一种旋转编码器的补偿方法和补偿系统
US10914612B2 (en) 2018-01-29 2021-02-09 Faro Technologies, Inc. Indexed optical encoder
JP2019158848A (ja) * 2018-03-16 2019-09-19 富士電機株式会社 絶対位置情報検出装置、及び、絶対位置情報検出装置の制御方法
CN109375038B (zh) * 2018-11-30 2020-09-11 江苏永钢集团有限公司 一种光电传感器快速校线装置及校线方法
US10963724B2 (en) 2019-04-01 2021-03-30 Novanta Corporation Absolute position encoder using a focused laser beam to detect position code words
EP3783318B1 (fr) 2019-08-19 2024-02-07 Goodrich Corporation Détermination de position de soupapes
EP4130683A4 (fr) * 2020-03-31 2023-08-23 Dai Nippon Printing Co., Ltd. Microscope à échelle réfléchissant pour codeur et codeur optique réfléchissant
CN112556739B (zh) * 2020-11-11 2022-05-20 深圳市海浦蒙特科技有限公司 旋转编码器的绝对位置参考点校准方法及装置
US11828629B2 (en) * 2021-05-28 2023-11-28 Pixart Imaging (Penang) Sdn. Bhd. Multi-track optical encoder
CN119826875B (zh) * 2024-12-23 2025-11-25 传周半导体科技(上海)有限公司 光电编码器窜扰信号实时减除系统

Citations (33)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3187187A (en) * 1962-01-24 1965-06-01 Wayne George Corp Photoelectric shaft angle encoder
US3307039A (en) * 1963-03-04 1967-02-28 Siemens Ag Albis Gap pattern for chopper of radiation search system
US4078173A (en) * 1976-06-24 1978-03-07 Pertec Computer Corporation Light amplitude control system for position and motion transducers
US4162399A (en) * 1977-09-16 1979-07-24 Bei Electronics, Inc. Optical encoder with fiber optics
US4410798A (en) * 1981-06-10 1983-10-18 Itek Corporation Incremental optical encoder system with addressable index
US4524347A (en) * 1980-05-15 1985-06-18 Ferranti Limited Position encoder
US4602155A (en) * 1983-07-25 1986-07-22 Bei Electronics, Inc. Zero reference generating method and apparatus for optical encoders
US4678908A (en) * 1983-07-25 1987-07-07 Bei Electronics, Inc. Zero reference generating method and apparatus for optical encoders
US4712000A (en) * 1983-10-21 1987-12-08 Canon Kabushiki Kaisha Rotary encoder with source-adjacent light sampling and control
US4794251A (en) * 1986-11-19 1988-12-27 Kern & Company Ltd. Apparatus for measuring lengths or angles
US4920259A (en) * 1988-09-30 1990-04-24 Hewlett-Packard Company Apparatus for producing a phase insensitive index pulse for motion encoders
US4945231A (en) * 1988-06-02 1990-07-31 Toyota Jidosha Kabushiki Kaisha Compound rotary encoder for detecting the rotation angle and the number of rotations of a rotor shaft
US4967071A (en) * 1989-03-10 1990-10-30 Kavlico Corporation Fiber optic position sensor
US5003170A (en) * 1987-05-13 1991-03-26 Matsushita Electric Industrial Co., Ltd. Reference signal generation apparatus for position detector with Fraunhofer diffraction
US5053618A (en) * 1990-03-30 1991-10-01 Bei Electronics, Inc. Index track support structure
US5355220A (en) * 1989-11-13 1994-10-11 Ricoh Company, Ltd. Optical movement measuring method and apparatus using interference fringes generated by overlapping spots of diffracted lights of different orders of diffraction from a line source
US5486923A (en) * 1992-05-05 1996-01-23 Microe Apparatus for detecting relative movement wherein a detecting means is positioned in the region of natural interference
US5559600A (en) * 1992-05-05 1996-09-24 Microe, Inc. Apparatus for detecting relative movement
US5880882A (en) * 1993-02-11 1999-03-09 Dr. Johannes Heidenhain Gmbh Scale and method for making a scale
US5909283A (en) * 1997-10-07 1999-06-01 Eselun; Steven Albert Linear encoder using diverging light beam diffraction
US20020000514A1 (en) * 1998-09-21 2002-01-03 Osram Opto Semiconductors Gmbh & Co. Ohg Method for a quantitative detection of a linear and rotary movement
US20030155489A1 (en) * 2001-12-28 2003-08-21 Fuji Xerox Co., Ltd. Optical encoder and scale for encoder
US6977368B2 (en) * 2000-10-31 2005-12-20 Dr. Johannes Heidenhain Gmbh Method for measuring position and position measuring device for carrying out said method
US7002137B2 (en) * 2001-08-30 2006-02-21 Gsi Lumonics Corporation Reference point talbot encoder
US7012677B2 (en) * 2002-06-28 2006-03-14 Stegman Gmbh & Co. Kg Optoelectronic angle measuring instrument and method for its production
US20060126474A1 (en) * 2004-12-11 2006-06-15 Hanks Darwin M Method and apparatus for acquiring an index mark
US20060186360A1 (en) * 2001-11-02 2006-08-24 Gsi Group Corporation Optical encoder with burst generator for generating burst output signals
US7141780B2 (en) * 2001-02-14 2006-11-28 Renishaw Plc Position determination system for determining the position of one relatively moveable part relative to another relatively movable part
US20070018084A1 (en) * 2003-02-12 2007-01-25 Mitutoyo Corporation Optical configuration for imaging-type optical encoders
US7368705B2 (en) * 2003-11-17 2008-05-06 Gsi Group Corporation Absolute encoder employing linked sub-encoders and beat track
US20080156973A1 (en) * 2006-12-29 2008-07-03 Weng Fei Wong Photosensor array for optical encoder
US8068040B2 (en) * 2005-02-25 2011-11-29 Avago Technologies Ecbu Ip (Singapore) Pte. Ltd. Optical encoder with integrated monitor
US8109906B2 (en) * 2005-03-17 2012-02-07 Smisson-Cartledge Biomedical Llc Control of a pump device

Family Cites Families (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4355279A (en) * 1980-12-29 1982-10-19 Hewlett-Packard Company Means and method for velocity decoding
US5038243A (en) * 1989-07-19 1991-08-06 Hewlett-Packard Company Local initialization for incremental encoder
US5981941A (en) * 1996-05-20 1999-11-09 Matsushita Electric Industrial Co., Ltd. Optical encorder for detection having a moving reference point
JP2003083823A (ja) * 2001-09-14 2003-03-19 Koyo Seiko Co Ltd 回転角検出装置、トルク検出装置及び舵取装置
JP2002228488A (ja) * 2001-02-06 2002-08-14 Canon Inc エンコーダ出力信号の自動調整装置および自動調整方法
JP2005003559A (ja) * 2003-06-12 2005-01-06 Canon Inc 位置検出装置、光学装置および位置検出方法
JP4265929B2 (ja) * 2003-05-20 2009-05-20 株式会社ミツトヨ 変位測定装置
JP2005106613A (ja) * 2003-09-30 2005-04-21 Koyo Seiko Co Ltd 回転角度検出装置及びトルク検出装置
US7066591B2 (en) * 2004-02-14 2006-06-27 Hewlett-Packard Development Company, L.P. Analog encoder
JP4877573B2 (ja) * 2005-10-28 2012-02-15 株式会社ニコン エンコーダディスクおよびエンコーダ
JP5125320B2 (ja) * 2007-08-28 2013-01-23 パナソニック株式会社 エンコーダの補正値制御方法
JP5240198B2 (ja) * 2007-09-05 2013-07-17 株式会社ニコン 光学式エンコーダ用反射板およびその製造方法、ならびに光学式エンコーダ
DE112009002101T5 (de) 2008-08-28 2012-01-12 Faro Technologies, Inc. Mit einem Index versehender optischer Encoder, Verfahren zum Indexieren eines optischen Encoders und Verfahren zum dynamischen Einstellen von Verstärkung und Offset in einem optischen Encoder
JP5115419B2 (ja) * 2008-09-18 2013-01-09 パナソニック株式会社 光学式エンコーダ

Patent Citations (33)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3187187A (en) * 1962-01-24 1965-06-01 Wayne George Corp Photoelectric shaft angle encoder
US3307039A (en) * 1963-03-04 1967-02-28 Siemens Ag Albis Gap pattern for chopper of radiation search system
US4078173A (en) * 1976-06-24 1978-03-07 Pertec Computer Corporation Light amplitude control system for position and motion transducers
US4162399A (en) * 1977-09-16 1979-07-24 Bei Electronics, Inc. Optical encoder with fiber optics
US4524347A (en) * 1980-05-15 1985-06-18 Ferranti Limited Position encoder
US4410798A (en) * 1981-06-10 1983-10-18 Itek Corporation Incremental optical encoder system with addressable index
US4602155A (en) * 1983-07-25 1986-07-22 Bei Electronics, Inc. Zero reference generating method and apparatus for optical encoders
US4678908A (en) * 1983-07-25 1987-07-07 Bei Electronics, Inc. Zero reference generating method and apparatus for optical encoders
US4712000A (en) * 1983-10-21 1987-12-08 Canon Kabushiki Kaisha Rotary encoder with source-adjacent light sampling and control
US4794251A (en) * 1986-11-19 1988-12-27 Kern & Company Ltd. Apparatus for measuring lengths or angles
US5003170A (en) * 1987-05-13 1991-03-26 Matsushita Electric Industrial Co., Ltd. Reference signal generation apparatus for position detector with Fraunhofer diffraction
US4945231A (en) * 1988-06-02 1990-07-31 Toyota Jidosha Kabushiki Kaisha Compound rotary encoder for detecting the rotation angle and the number of rotations of a rotor shaft
US4920259A (en) * 1988-09-30 1990-04-24 Hewlett-Packard Company Apparatus for producing a phase insensitive index pulse for motion encoders
US4967071A (en) * 1989-03-10 1990-10-30 Kavlico Corporation Fiber optic position sensor
US5355220A (en) * 1989-11-13 1994-10-11 Ricoh Company, Ltd. Optical movement measuring method and apparatus using interference fringes generated by overlapping spots of diffracted lights of different orders of diffraction from a line source
US5053618A (en) * 1990-03-30 1991-10-01 Bei Electronics, Inc. Index track support structure
US5486923A (en) * 1992-05-05 1996-01-23 Microe Apparatus for detecting relative movement wherein a detecting means is positioned in the region of natural interference
US5559600A (en) * 1992-05-05 1996-09-24 Microe, Inc. Apparatus for detecting relative movement
US5880882A (en) * 1993-02-11 1999-03-09 Dr. Johannes Heidenhain Gmbh Scale and method for making a scale
US5909283A (en) * 1997-10-07 1999-06-01 Eselun; Steven Albert Linear encoder using diverging light beam diffraction
US20020000514A1 (en) * 1998-09-21 2002-01-03 Osram Opto Semiconductors Gmbh & Co. Ohg Method for a quantitative detection of a linear and rotary movement
US6977368B2 (en) * 2000-10-31 2005-12-20 Dr. Johannes Heidenhain Gmbh Method for measuring position and position measuring device for carrying out said method
US7141780B2 (en) * 2001-02-14 2006-11-28 Renishaw Plc Position determination system for determining the position of one relatively moveable part relative to another relatively movable part
US7002137B2 (en) * 2001-08-30 2006-02-21 Gsi Lumonics Corporation Reference point talbot encoder
US20060186360A1 (en) * 2001-11-02 2006-08-24 Gsi Group Corporation Optical encoder with burst generator for generating burst output signals
US20030155489A1 (en) * 2001-12-28 2003-08-21 Fuji Xerox Co., Ltd. Optical encoder and scale for encoder
US7012677B2 (en) * 2002-06-28 2006-03-14 Stegman Gmbh & Co. Kg Optoelectronic angle measuring instrument and method for its production
US20070018084A1 (en) * 2003-02-12 2007-01-25 Mitutoyo Corporation Optical configuration for imaging-type optical encoders
US7368705B2 (en) * 2003-11-17 2008-05-06 Gsi Group Corporation Absolute encoder employing linked sub-encoders and beat track
US20060126474A1 (en) * 2004-12-11 2006-06-15 Hanks Darwin M Method and apparatus for acquiring an index mark
US8068040B2 (en) * 2005-02-25 2011-11-29 Avago Technologies Ecbu Ip (Singapore) Pte. Ltd. Optical encoder with integrated monitor
US8109906B2 (en) * 2005-03-17 2012-02-07 Smisson-Cartledge Biomedical Llc Control of a pump device
US20080156973A1 (en) * 2006-12-29 2008-07-03 Weng Fei Wong Photosensor array for optical encoder

Cited By (71)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8476579B2 (en) 2008-08-28 2013-07-02 Faro Technologies, Inc. Indexed optical encoder, method for indexing an optical encoder, and method for dynamically adjusting gain and offset in an optical encoder
US8513589B2 (en) 2008-08-28 2013-08-20 Faro Technologies, Inc. Indexed optical encoder, method for indexing an optical encoder, and method for dynamically adjusting gain and offset in an optical encoder
US9551575B2 (en) 2009-03-25 2017-01-24 Faro Technologies, Inc. Laser scanner having a multi-color light source and real-time color receiver
US9074883B2 (en) 2009-03-25 2015-07-07 Faro Technologies, Inc. Device for optically scanning and measuring an environment
US9529083B2 (en) 2009-11-20 2016-12-27 Faro Technologies, Inc. Three-dimensional scanner with enhanced spectroscopic energy detector
US9210288B2 (en) 2009-11-20 2015-12-08 Faro Technologies, Inc. Three-dimensional scanner with dichroic beam splitters to capture a variety of signals
US9113023B2 (en) 2009-11-20 2015-08-18 Faro Technologies, Inc. Three-dimensional scanner with spectroscopic energy detector
US9417316B2 (en) 2009-11-20 2016-08-16 Faro Technologies, Inc. Device for optically scanning and measuring an environment
WO2011085075A2 (fr) 2010-01-07 2011-07-14 Gen9, Inc. Assemblage de polynucléotides haute fidélité
US8630314B2 (en) 2010-01-11 2014-01-14 Faro Technologies, Inc. Method and apparatus for synchronizing measurements taken by multiple metrology devices
US9628775B2 (en) 2010-01-20 2017-04-18 Faro Technologies, Inc. Articulated arm coordinate measurement machine having a 2D camera and method of obtaining 3D representations
US8875409B2 (en) 2010-01-20 2014-11-04 Faro Technologies, Inc. Coordinate measurement machines with removable accessories
US8533967B2 (en) 2010-01-20 2013-09-17 Faro Technologies, Inc. Coordinate measurement machines with removable accessories
US8537374B2 (en) 2010-01-20 2013-09-17 Faro Technologies, Inc. Coordinate measuring machine having an illuminated probe end and method of operation
US8601702B2 (en) 2010-01-20 2013-12-10 Faro Technologies, Inc. Display for coordinate measuring machine
US8615893B2 (en) 2010-01-20 2013-12-31 Faro Technologies, Inc. Portable articulated arm coordinate measuring machine having integrated software controls
US8284407B2 (en) 2010-01-20 2012-10-09 Faro Technologies, Inc. Coordinate measuring machine having an illuminated probe end and method of operation
US8638446B2 (en) 2010-01-20 2014-01-28 Faro Technologies, Inc. Laser scanner or laser tracker having a projector
US20110173825A1 (en) * 2010-01-20 2011-07-21 Faro Technologies, Inc. Counter balance for coordinate measurement device
US8677643B2 (en) 2010-01-20 2014-03-25 Faro Technologies, Inc. Coordinate measurement machines with removable accessories
US8683709B2 (en) 2010-01-20 2014-04-01 Faro Technologies, Inc. Portable articulated arm coordinate measuring machine with multi-bus arm technology
US8763266B2 (en) 2010-01-20 2014-07-01 Faro Technologies, Inc. Coordinate measurement device
US8832954B2 (en) 2010-01-20 2014-09-16 Faro Technologies, Inc. Coordinate measurement machines with removable accessories
US10281259B2 (en) 2010-01-20 2019-05-07 Faro Technologies, Inc. Articulated arm coordinate measurement machine that uses a 2D camera to determine 3D coordinates of smoothly continuous edge features
US8898919B2 (en) 2010-01-20 2014-12-02 Faro Technologies, Inc. Coordinate measurement machine with distance meter used to establish frame of reference
US8942940B2 (en) 2010-01-20 2015-01-27 Faro Technologies, Inc. Portable articulated arm coordinate measuring machine and integrated electronic data processing system
US10060722B2 (en) 2010-01-20 2018-08-28 Faro Technologies, Inc. Articulated arm coordinate measurement machine having a 2D camera and method of obtaining 3D representations
US8276286B2 (en) 2010-01-20 2012-10-02 Faro Technologies, Inc. Display for coordinate measuring machine
US9009000B2 (en) 2010-01-20 2015-04-14 Faro Technologies, Inc. Method for evaluating mounting stability of articulated arm coordinate measurement machine using inclinometers
US8171650B2 (en) 2010-01-20 2012-05-08 Faro Technologies, Inc. Intelligent repeatable arm mounting system
US8028432B2 (en) 2010-01-20 2011-10-04 Faro Technologies, Inc. Mounting device for a coordinate measuring machine
US9607239B2 (en) 2010-01-20 2017-03-28 Faro Technologies, Inc. Articulated arm coordinate measurement machine having a 2D camera and method of obtaining 3D representations
US9163922B2 (en) 2010-01-20 2015-10-20 Faro Technologies, Inc. Coordinate measurement machine with distance meter and camera to determine dimensions within camera images
US20110178762A1 (en) * 2010-01-20 2011-07-21 Faro Technologies, Inc. Portable Articulated Arm Coordinate Measuring Machine with Multiple Communication Channels
US8001697B2 (en) 2010-01-20 2011-08-23 Faro Technologies, Inc. Counter balance for coordinate measurement device
US20110229151A1 (en) * 2010-03-18 2011-09-22 Mitutoyo Corporation Photoelectric encoder
US8666261B2 (en) * 2010-03-18 2014-03-04 Mitutoyo Corporation Photoelectric encoder
US9329271B2 (en) 2010-05-10 2016-05-03 Faro Technologies, Inc. Method for optically scanning and measuring an environment
US9684078B2 (en) 2010-05-10 2017-06-20 Faro Technologies, Inc. Method for optically scanning and measuring an environment
US9168654B2 (en) 2010-11-16 2015-10-27 Faro Technologies, Inc. Coordinate measuring machines with dual layer arm
US20130105675A1 (en) * 2011-10-28 2013-05-02 Mitutoyo Corporation Displacement detecting device, displacement detecting method, and computer-readable medium
US8981282B2 (en) * 2011-10-28 2015-03-17 Mitutoyo Corporation Displacement detecting device, displacement detecting method, and computer-readable medium
US9417056B2 (en) 2012-01-25 2016-08-16 Faro Technologies, Inc. Device for optically scanning and measuring an environment
US8997362B2 (en) 2012-07-17 2015-04-07 Faro Technologies, Inc. Portable articulated arm coordinate measuring machine with optical communications bus
US10203413B2 (en) 2012-10-05 2019-02-12 Faro Technologies, Inc. Using a two-dimensional scanner to speed registration of three-dimensional scan data
US11112501B2 (en) 2012-10-05 2021-09-07 Faro Technologies, Inc. Using a two-dimensional scanner to speed registration of three-dimensional scan data
US11815600B2 (en) 2012-10-05 2023-11-14 Faro Technologies, Inc. Using a two-dimensional scanner to speed registration of three-dimensional scan data
US9739886B2 (en) 2012-10-05 2017-08-22 Faro Technologies, Inc. Using a two-dimensional scanner to speed registration of three-dimensional scan data
US9746559B2 (en) 2012-10-05 2017-08-29 Faro Technologies, Inc. Using two-dimensional camera images to speed registration of three-dimensional scans
US9618620B2 (en) 2012-10-05 2017-04-11 Faro Technologies, Inc. Using depth-camera images to speed registration of three-dimensional scans
US9372265B2 (en) 2012-10-05 2016-06-21 Faro Technologies, Inc. Intermediate two-dimensional scanning with a three-dimensional scanner to speed registration
US10067231B2 (en) 2012-10-05 2018-09-04 Faro Technologies, Inc. Registration calculation of three-dimensional scanner data performed between scans based on measurements by two-dimensional scanner
US11035955B2 (en) 2012-10-05 2021-06-15 Faro Technologies, Inc. Registration calculation of three-dimensional scanner data performed between scans based on measurements by two-dimensional scanner
US10739458B2 (en) 2012-10-05 2020-08-11 Faro Technologies, Inc. Using two-dimensional camera images to speed registration of three-dimensional scans
US9513107B2 (en) 2012-10-05 2016-12-06 Faro Technologies, Inc. Registration calculation between three-dimensional (3D) scans based on two-dimensional (2D) scan data from a 3D scanner
US20150292919A1 (en) * 2014-04-14 2015-10-15 Canon Kabushiki Kaisha Absolute encoder, processing method, program, driving apparatus, and industrial machine
US10209104B2 (en) * 2014-04-14 2019-02-19 Canon Kabushiki Kaisha Absolute encoder, processing method, program, driving apparatus, and industrial machine
US11054435B2 (en) 2015-02-24 2021-07-06 Continental Automotiive France Method and device for processing a signal produced by a sensor for detecting the rotation of a rotating target
US10215595B2 (en) 2015-04-22 2019-02-26 Faro Technologies, Inc. Indexed optical encoder
US20160321810A1 (en) * 2015-04-28 2016-11-03 Pixart Imaging (Penang) Sdn. Bhd. Optical navigation sensor, electronic device with optical navigation function and operation method thereof
US10175037B2 (en) 2015-12-27 2019-01-08 Faro Technologies, Inc. 3-D measuring device with battery pack
US20170254670A1 (en) * 2016-03-04 2017-09-07 National Tsing Hua University Absolute position detecting device and method
US10145709B2 (en) * 2016-03-04 2018-12-04 National Tsing Hua University Absolute position detecting device and method
US10642243B2 (en) * 2018-03-01 2020-05-05 Semiconductor Components Industries, Llc Methods and apparatus for an encoder
US11397418B2 (en) 2018-03-01 2022-07-26 Semiconductor Components Industries, Llc Methods and apparatus for an encoder
US20190271961A1 (en) * 2018-03-01 2019-09-05 Semiconductor Components Industries, Llc Methods and apparatus for an encoder
US20220163353A1 (en) * 2020-11-25 2022-05-26 Pixart Imaging Inc. Anti-pollution optical encoder and signal processing circuit thereof
US11740108B2 (en) * 2020-11-25 2023-08-29 Pixart Imaging Inc. Anti-pollution optical encoder
CN115248054A (zh) * 2021-04-26 2022-10-28 原相科技股份有限公司 可调节索引输出增益的光学式编码器
CN116625281A (zh) * 2022-12-06 2023-08-22 山东林诺威神工控技术有限公司 编码器的偏心位置计算矫正方法
US20250231050A1 (en) * 2024-01-11 2025-07-17 Pixart Imaging Inc. Code wheel and encoding system

Also Published As

Publication number Publication date
GB201011528D0 (en) 2010-08-25
GB2496236B (en) 2013-07-17
CN102007378B (zh) 2013-10-16
CN102007378A (zh) 2011-04-06
GB2468263A (en) 2010-09-01
JP5318212B2 (ja) 2013-10-16
JP5237498B2 (ja) 2013-07-17
GB2468263B (en) 2013-04-03
US8513589B2 (en) 2013-08-20
JP2012501453A (ja) 2012-01-19
GB2496230A (en) 2013-05-08
GB201212858D0 (en) 2012-09-05
DE112009002101T5 (de) 2012-01-12
GB2496236A (en) 2013-05-08
US8476579B2 (en) 2013-07-02
WO2010025365A2 (fr) 2010-03-04
JP2013054040A (ja) 2013-03-21
GB201209634D0 (en) 2012-07-11
WO2010025365A3 (fr) 2010-07-29
US20130306850A1 (en) 2013-11-21
US20130112861A1 (en) 2013-05-09
GB2496230B (en) 2013-07-17
US20130116959A1 (en) 2013-05-09

Similar Documents

Publication Publication Date Title
US8513589B2 (en) Indexed optical encoder, method for indexing an optical encoder, and method for dynamically adjusting gain and offset in an optical encoder
KR100738495B1 (ko) 광학식 엔코더
KR101910672B1 (ko) 위치 검출 장치용 포토 센서, 이를 이용한 위치 검출 장치 및 위치 검출 방법
KR101449357B1 (ko) 광학식 인코더
US9464924B2 (en) Scale, displacement detection apparatus, lens apparatus, image pickup system, and assembling apparatus
JP6400036B2 (ja) 位置検出装置、工作装置、および、露光装置
US9116163B2 (en) Displacement measuring apparatus
US20060180748A1 (en) Position measuring instrument
US6914235B2 (en) Position measuring system and method for operating a position measuring system
JP4703059B2 (ja) 光電式エンコーダ
JPH08178700A (ja) インクリメンタルエンコーダ
US4883955A (en) Optical encoder with converging means
CN118089801A (zh) 一种狭缝部、光电编码器、伺服电机和伺服系统
CN113686364A (zh) 可校正元件相对位置的光学编码器及其位置校正方法
JP3639377B2 (ja) 光学式変位センサ
JP2001343256A (ja) 光学式エンコーダ
JPH0861990A (ja) エンコーダ
JP3808192B2 (ja) 移動量測定装置、及び移動量測定方法
JPH0587590A (ja) エンコーダ
JP2008116229A (ja) インクリメンタル型ロータリエンコーダ
JP3049302B2 (ja) 光学式変位検出器
JPH0587591A (ja) エンコーダ
JP2006284277A (ja) エンコーダ

Legal Events

Date Code Title Description
AS Assignment

Owner name: FARO TECHNOLOGIES, INC.,FLORIDA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:YORK, FREDERICK;REEL/FRAME:023521/0740

Effective date: 20090902

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION