WO2005124282A2 - Scale reading apparatus - Google Patents

Scale reading apparatus Download PDF

Info

Publication number
WO2005124282A2
WO2005124282A2 PCT/GB2005/002421 GB2005002421W WO2005124282A2 WO 2005124282 A2 WO2005124282 A2 WO 2005124282A2 GB 2005002421 W GB2005002421 W GB 2005002421W WO 2005124282 A2 WO2005124282 A2 WO 2005124282A2
Authority
WO
WIPO (PCT)
Prior art keywords
scale
reference mark
detecting
incremental
readhead
Prior art date
Application number
PCT/GB2005/002421
Other languages
French (fr)
Other versions
WO2005124282A3 (en
Inventor
David Roberts Mcmurtry
James Reynolds Henshaw
Original Assignee
Renishaw Plc
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
Family has litigation
First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=32750195&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=WO2005124282(A2) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by Renishaw Plc filed Critical Renishaw Plc
Priority to JP2007517439A priority Critical patent/JP4932706B2/en
Priority to EP05758458.3A priority patent/EP1766334B2/en
Priority to US11/629,853 priority patent/US7659992B2/en
Publication of WO2005124282A2 publication Critical patent/WO2005124282A2/en
Publication of WO2005124282A3 publication Critical patent/WO2005124282A3/en

Links

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
    • G01D5/36—Forming the light into pulses
    • G01D5/366—Particular pulse shapes
    • 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

Definitions

  • the present invention relates to optical scale reading apparatus comprising a scale and a readhead movable relative to the scale.
  • the invention relates to an incremental scale having embedded reference marks, and a readhead for that scale.
  • a known form of scale reading apparatus for measuring relative displacement of two members comprises a scale on one of the members having scale marks defining a pattern and a readhead provided on the other member.
  • An incremental scale has scale marks defining a periodic pattern which generates a periodic signal at the readhead when relative movement between the scale and the readhead takes place. These periodic signals produce an up/down count which enables displacement between the scale and the readhead to be determined.
  • Measurement scales may have reference marks which when detected by the readhead enable the exact position of the readhead to be determined. Reference marks may for example enable the accuracy of the incremental count to be verified.
  • Reference marks are typically provided on a scale track parallel to the incremental track. This has the disadvantage that it increases the width of the scale. Furthermore, it has the disadvantage that yawing of the readhead can cause errors in the position of the reference mark relative to the incremental scale as detected by the readhead.
  • thermal longitudinal expansion of the readhead can also cause errors in the relative positions of the reference mark and incremental scale as detected by the readhead.
  • the present invention provides apparatus for measuring displacement between two members, comprising: a scale on one of the members having periodic scale markings forming an incremental pattern and at least one reference mark embedded in the incremental pattern; a read head provided on the other member; periodic diffraction means provided in the readhead for interacting with a light pattern modulated by the incremental pattern on the scale to produce interference fringes having movement relative to said readhead responsive to said displacement; first detecting means for detecting said movement of said interference fringes; imaging means provided in the readhead for imaging the reference mark; second detecting means for detecting said image of the reference mark; wherein the imaging means is located between the scale and the second detecting means.
  • the periodic diffraction means and the imaging means may be provided on a single unit.
  • the imaging means may comprise a lens, for example a cylindrical lens.
  • the imaging means may comprise a Fresnel zone plate.
  • the imaging means may be at least partially incorporated within the periodic diffraction means.
  • a masking region may be provided between the imaging means and the periodic diffraction means.
  • the first and second detecting means may be provided at a single detecting unit.
  • the second detecting means may be at least partly incorporated within the first detecting means.
  • a single light source may be used for the incremental pattern and the reference mark.
  • the imaging means, periodic diffraction means, first and second detecting means and light source may be disposed in a single plane.
  • the plane may be perpendicular to the direction of the scale.
  • Fig 1 is a perspective view of the scale reading apparatus
  • Fig 2 is a graph representing the output signals from the split detector of Fig 1
  • Fig 3 is a graph representing the difference between the output signals of Fig 2
  • Fig 4 illustrates a plan view of the optical element of a second embodiment of the invention
  • Fig 5 illustrates a plan view of the detector of a second embodiment of the invention
  • Fig 6 illustrates a plan view of the optical element of a third embodiment of the invention
  • Fig 7 illustrates a plan view of a detector according to a third embodiment of the invention
  • Fig 8 illustrates a plan view of an optical element in which a Fresnel zone plate is incorporated within the index grating
  • Fig 9 is a perspective view of the scale reading apparatus of Fig 1, having the detector of Fig 5 and optical element of Fig 8.
  • FIG 1 illustrates a first embodiment of the present invention.
  • a scale 10 has periodic markings 12 made up of alternate reflective and non-reflective lines which form the incremental scale.
  • a reference mark 14 is embedded in the scale by the removal or addition of lines, thus forming a reflective mark.
  • a readhead (not shown) is movable relative to the scale and contains optics which comprise a light source 16, an optical element 18 and a detector unit 20.
  • the light source 16 is directed towards the scale to illuminate the scale and produce a periodic light pattern from the incremental scale.
  • the optical element 18 has an index grating 22 which interacts with the periodic light pattern to form interference fringes at the detector unit 20.
  • the detector unit 20 has a photodetector array 24 which detects these interference fringes to produce a periodic signal. Movement of the readhead relative to the scale causes movement of the interference fringes relative to this detector portion 24 thus producing an up/down count which enables a measurement of displacement.
  • a scale and readhead of this type are described in our earlier European Patent No. 207121.
  • the index grating 22 is positioned between the scale 10 and detector 22.
  • the scale 10 acts as an object which is imaged by the index grating 22.
  • This arrangement allows the reference mark to be embedded in the incremental scale without significant loss of signal.
  • this arrangement allows the imaging optics 18 to be located between the scale 10 and detector without significant loss of signal.
  • the index grating acts as the object and is imaged by the scale. In this case, placement of a reference mark in the scale or placing imaging optics between the scale and detector has a more significant effect on the signal to noise ratio.
  • the reference mark may be formed by the removal of lines or the addition of lines. Alternatively it may comprise any pattern which can be differentiated from the incremental scale.
  • the reference mark may comprise an autocorrelator in which the reference mark forms a pattern interlaced with the incremental scale and a matching mask is provided in the readhead, for example as described in International Patent Application O02/065061.
  • a change in the intensity of light reflected by the scale 10 is imaged by a lens 26 in the optical element 18 onto the detector 20.
  • the detector 20 has a split detector 28 onto which light from the reference mark 14 is imaged.
  • Fig 2 illustrates the outputs from the two halves of the split detector 28 as the readhead moves along the scale. Signals SI and S2 from the two halves of the split detector are subtracted to form signal S3 shown in Fig 3.
  • the position of the reference mark is typically where the falling edge of signal S3 crosses a known threshold in the reading direction shown.
  • split detector is used to detect the reference mark
  • other types of detector may be used, for example the outputs from three detector elements could be combined.
  • a multi-role detector element may be used to detect both the incremental and reference mark signals.
  • the lens 26 illustrated in Fig 1 is a cylindrical lens mounted on a plate 30.
  • other types of lens having the same optical function may be used, for example a spherical lens, a linear microlens array or a Fresnel zone plate.
  • the lens may be mounted on the plate 30 by any suitable fashion, e.g. gluing or moulding.
  • the lens 26 does not need to be integral with the optical element 18 which holds the index grating 22.
  • Fig 1 still works when a focal centre of the lens is not level with the index grating.
  • optical element and detector Various different arrangements of the optical element and detector are possible, for example the positions of the incremental related portions and the reference mark related portions of the optical element and/or detector may be interchanged.
  • Figs 4 and 5 illustrate the optical element and detector respectively in which the incremental and reference mark optics are combined together.
  • the lens 26 is placed within the index grating 22 and in Fig 5 the split detector 28 is located within the incremental detecting elements 24.
  • Figs 6 and 7 illustrate a further embodiment of the optical element and a detector respectively.
  • Fig 6 illustrates an optical element 18 in which the lens 26 extends partially into the index grating portion 22.
  • Fig 7 illustrates the associated detector with its reference mark detector 28 extending partially into the incremental detector portion 24.
  • the optical element may combine the incremental and reference mark optics, for example in a diffractive optical element (DOE), multi-level optics or a 3-dimensional optical component, such as a volume holograph etc.
  • DOE diffractive optical element
  • the lens may comprise many lens segments, for example a Fresnel lens.
  • Fig 8 illustrates an optical element, in which a Fresnel zone plate 29 is incorporated within the index grating 21.
  • a mask region 31 may be provided on either side of the Fresnel zone plate to improve the system response. This masks stray light from the incremental scale from being detected by the reference mark detector.
  • the mask region may be formed by chrome on glass or any other suitable means. Such a mask may be used with imaging means other than a Fresnel zone plate .
  • the imaging lens and diffraction grating may be located separately. They are not required to be in the same plane.
  • This region 31 could be left blank, allowing light to be transmitted without directing it to the reference mark detector.
  • Fig 9 illustrates an embodiment similar to that shown in Fig 1 but having an optical element as illustrated in Fig 8 (i.e. having Fresnel zone plate 29 incorporated within the index grating 21) and a detector as illustrated in Fig 5 (i.e. in which the split detector 28 is located within the incremental detecting elements 24) .
  • the incremental and reference mark optics are combined.
  • Unwanted light may fall on the detectors, such as background unmodulated light and cross contamination of modulated light from the incremental/reference mark systems.
  • Baffles can be used in the readhead to reduce this unwanted light.
  • cross contamination may be reduced by using different light sources of different wavelengths for the incremental and reference mark systems. Filters may be provided so that the reference mark portions and incremental portions of the detector only detect light of the specific wavelength used in that system.
  • a single light source has the advantage that the incremental and reference mark signals share the same age, temperature coefficient etc.
  • the phase of the incremental and reference mark signals are kept steady, reducing electronics and current consumption.
  • This arrangement of scale and readhead has the advantage that the footprint on the scale of the incremental and reference marks is at a similar location on the scale and the light source, optical element and detector are in the same plane 32 (shown in Fig 1) for both the incremental and reference mark systems.
  • This arrangement has the benefit that there is reduced parallax and reduced sensitivity to yaw.
  • the reference mark detector and incremental detector are on a single detector unit and the lens and index grating are on a single optical element, problems due to longitudinal expansion of the readhead are eliminated.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optical Transform (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

Apparatus for measuring displacement between two members. A scale is provided on one member and has an incremental pattern with at least one reference mark embedded in it. A read head is provided on the other member and comprises a periodic diffraction means for interacting with a light pattern modulated by the incremental pattern on the scale to produce interference fringes having movement relative to said readhead responsive to said displacement, first detecting means for detecting the movement of the interference fringes, imaging means for imaging the reference mark and second detecting means for detecting the image of the reference mark.

Description

SCALE READING APPARATUS
The present invention relates to optical scale reading apparatus comprising a scale and a readhead movable relative to the scale. In particular the invention relates to an incremental scale having embedded reference marks, and a readhead for that scale.
A known form of scale reading apparatus for measuring relative displacement of two members comprises a scale on one of the members having scale marks defining a pattern and a readhead provided on the other member. An incremental scale has scale marks defining a periodic pattern which generates a periodic signal at the readhead when relative movement between the scale and the readhead takes place. These periodic signals produce an up/down count which enables displacement between the scale and the readhead to be determined.
Our earlier European Patent No. 207121 describes an incremental scale reading system which has a filtering effect so that the signal produced at the photodetector array is largely immune to parts of the scale being obscured for example by contamination.
Measurement scales may have reference marks which when detected by the readhead enable the exact position of the readhead to be determined. Reference marks may for example enable the accuracy of the incremental count to be verified.
Reference marks are typically provided on a scale track parallel to the incremental track. This has the disadvantage that it increases the width of the scale. Furthermore, it has the disadvantage that yawing of the readhead can cause errors in the position of the reference mark relative to the incremental scale as detected by the readhead.
As separate optics are used for detecting the light pattern produced from the incremental scale and the reference mark, thermal longitudinal expansion of the readhead can also cause errors in the relative positions of the reference mark and incremental scale as detected by the readhead.
The present invention provides apparatus for measuring displacement between two members, comprising: a scale on one of the members having periodic scale markings forming an incremental pattern and at least one reference mark embedded in the incremental pattern; a read head provided on the other member; periodic diffraction means provided in the readhead for interacting with a light pattern modulated by the incremental pattern on the scale to produce interference fringes having movement relative to said readhead responsive to said displacement; first detecting means for detecting said movement of said interference fringes; imaging means provided in the readhead for imaging the reference mark; second detecting means for detecting said image of the reference mark; wherein the imaging means is located between the scale and the second detecting means.
The periodic diffraction means and the imaging means may be provided on a single unit.
The imaging means may comprise a lens, for example a cylindrical lens. The imaging means may comprise a Fresnel zone plate. The imaging means may be at least partially incorporated within the periodic diffraction means. A masking region may be provided between the imaging means and the periodic diffraction means.
The first and second detecting means may be provided at a single detecting unit. The second detecting means may be at least partly incorporated within the first detecting means.
A single light source may be used for the incremental pattern and the reference mark.
The imaging means, periodic diffraction means, first and second detecting means and light source may be disposed in a single plane. The plane may be perpendicular to the direction of the scale.
The invention will now be described with reference to the accompanying drawings in which: Fig 1 is a perspective view of the scale reading apparatus; Fig 2 is a graph representing the output signals from the split detector of Fig 1; Fig 3 is a graph representing the difference between the output signals of Fig 2; Fig 4 illustrates a plan view of the optical element of a second embodiment of the invention; Fig 5 illustrates a plan view of the detector of a second embodiment of the invention; Fig 6 illustrates a plan view of the optical element of a third embodiment of the invention; Fig 7 illustrates a plan view of a detector according to a third embodiment of the invention; Fig 8 illustrates a plan view of an optical element in which a Fresnel zone plate is incorporated within the index grating; and Fig 9 is a perspective view of the scale reading apparatus of Fig 1, having the detector of Fig 5 and optical element of Fig 8.
Fig 1 illustrates a first embodiment of the present invention. A scale 10 has periodic markings 12 made up of alternate reflective and non-reflective lines which form the incremental scale. A reference mark 14 is embedded in the scale by the removal or addition of lines, thus forming a reflective mark.
A readhead (not shown) is movable relative to the scale and contains optics which comprise a light source 16, an optical element 18 and a detector unit 20. The light source 16 is directed towards the scale to illuminate the scale and produce a periodic light pattern from the incremental scale. The optical element 18 has an index grating 22 which interacts with the periodic light pattern to form interference fringes at the detector unit 20. The detector unit 20 has a photodetector array 24 which detects these interference fringes to produce a periodic signal. Movement of the readhead relative to the scale causes movement of the interference fringes relative to this detector portion 24 thus producing an up/down count which enables a measurement of displacement. A scale and readhead of this type are described in our earlier European Patent No. 207121. This arrangement has the advantage that due to a filtering effect of the optics, it is largely immune to the addition or removal of bits of the scale at the reference mark. Thus the readhead can pass over the reference mark with just a slight reduction in the signal to noise ratio. In this type of arrangement, the index grating 22 is positioned between the scale 10 and detector 22. In this arrangement the scale 10 acts as an object which is imaged by the index grating 22. This arrangement allows the reference mark to be embedded in the incremental scale without significant loss of signal. In addition, this arrangement allows the imaging optics 18 to be located between the scale 10 and detector without significant loss of signal. In known alternative arrangements in which the index grating is positioned between the light source and scale, the index grating acts as the object and is imaged by the scale. In this case, placement of a reference mark in the scale or placing imaging optics between the scale and detector has a more significant effect on the signal to noise ratio.
The reference mark may be formed by the removal of lines or the addition of lines. Alternatively it may comprise any pattern which can be differentiated from the incremental scale. For example, the reference mark may comprise an autocorrelator in which the reference mark forms a pattern interlaced with the incremental scale and a matching mask is provided in the readhead, for example as described in International Patent Application O02/065061. When the readhead passes over the reference mark 14 a change in the intensity of light reflected by the scale 10 is imaged by a lens 26 in the optical element 18 onto the detector 20. The detector 20 has a split detector 28 onto which light from the reference mark 14 is imaged. Fig 2 illustrates the outputs from the two halves of the split detector 28 as the readhead moves along the scale. Signals SI and S2 from the two halves of the split detector are subtracted to form signal S3 shown in Fig 3. The position of the reference mark is typically where the falling edge of signal S3 crosses a known threshold in the reading direction shown.
Although in this embodiment a split detector is used to detect the reference mark, other types of detector may be used, for example the outputs from three detector elements could be combined. A multi-role detector element may be used to detect both the incremental and reference mark signals.
The lens 26 illustrated in Fig 1 is a cylindrical lens mounted on a plate 30. However other types of lens having the same optical function may be used, for example a spherical lens, a linear microlens array or a Fresnel zone plate. The lens may be mounted on the plate 30 by any suitable fashion, e.g. gluing or moulding. The lens 26 does not need to be integral with the optical element 18 which holds the index grating 22.
The arrangement shown in Fig 1 still works when a focal centre of the lens is not level with the index grating.
Various different arrangements of the optical element and detector are possible, for example the positions of the incremental related portions and the reference mark related portions of the optical element and/or detector may be interchanged.
Figs 4 and 5 illustrate the optical element and detector respectively in which the incremental and reference mark optics are combined together. In Fig 4 the lens 26 is placed within the index grating 22 and in Fig 5 the split detector 28 is located within the incremental detecting elements 24.
Various degrees of intermingle of the reference mark with the incremental scale and their associated optics and detectors are possible. Figs 6 and 7 illustrate a further embodiment of the optical element and a detector respectively. Fig 6 illustrates an optical element 18 in which the lens 26 extends partially into the index grating portion 22. Fig 7 illustrates the associated detector with its reference mark detector 28 extending partially into the incremental detector portion 24.
The optical element may combine the incremental and reference mark optics, for example in a diffractive optical element (DOE), multi-level optics or a 3-dimensional optical component, such as a volume holograph etc. The lens may comprise many lens segments, for example a Fresnel lens.
Fig 8 illustrates an optical element, in which a Fresnel zone plate 29 is incorporated within the index grating 21. A mask region 31 may be provided on either side of the Fresnel zone plate to improve the system response. This masks stray light from the incremental scale from being detected by the reference mark detector. The mask region may be formed by chrome on glass or any other suitable means. Such a mask may be used with imaging means other than a Fresnel zone plate .
Alternatively, the imaging lens and diffraction grating may be located separately. They are not required to be in the same plane.
This region 31 could be left blank, allowing light to be transmitted without directing it to the reference mark detector.
Fig 9 illustrates an embodiment similar to that shown in Fig 1 but having an optical element as illustrated in Fig 8 (i.e. having Fresnel zone plate 29 incorporated within the index grating 21) and a detector as illustrated in Fig 5 (i.e. in which the split detector 28 is located within the incremental detecting elements 24) . In both the optical element and detector, the incremental and reference mark optics are combined.
Unwanted light may fall on the detectors, such as background unmodulated light and cross contamination of modulated light from the incremental/reference mark systems. Baffles can be used in the readhead to reduce this unwanted light. Furthermore cross contamination may be reduced by using different light sources of different wavelengths for the incremental and reference mark systems. Filters may be provided so that the reference mark portions and incremental portions of the detector only detect light of the specific wavelength used in that system.
However, a single light source has the advantage that the incremental and reference mark signals share the same age, temperature coefficient etc. Thus the phase of the incremental and reference mark signals are kept steady, reducing electronics and current consumption.
Furthermore, use of the same light source allows the signals from both systems to be compensated simultaneously using feedback from just one system.
This arrangement of scale and readhead has the advantage that the footprint on the scale of the incremental and reference marks is at a similar location on the scale and the light source, optical element and detector are in the same plane 32 (shown in Fig 1) for both the incremental and reference mark systems. This arrangement has the benefit that there is reduced parallax and reduced sensitivity to yaw.
If the reference mark detector and incremental detector are on a single detector unit and the lens and index grating are on a single optical element, problems due to longitudinal expansion of the readhead are eliminated.
Although the described embodiment is a linear scale reading system, this invention is also suitable for a rotary system or a two-dimensional system.

Claims

1. Apparatus for measuring displacement between two members, comprising: a scale on one of the members having periodic scale markings forming an incremental pattern and at least one reference mark embedded in the incremental pattern; a read head provided on the other member; periodic diffraction means provided in the readhead for interacting with a light pattern modulated by the incremental pattern on the scale to produce interference fringes having movement relative to said readhead responsive to said displacement; first detecting means for detecting said movement of said interference fringes; imaging means provided in the readhead for imaging the reference mark; second detecting means for detecting said image of the reference mark; wherein the imaging means is located between the scale and the second detecting means.
2. Apparatus according to claim 1 wherein the periodic diffraction means and the imaging means are provided on a single unit.
3. Apparatus according to any preceding claim wherein the imaging means comprises a lens. . Apparatus according to claim 3 wherein the lens comprises a cylindrical lens.
5. Apparatus according to any of claims 1-2 wherein the imaging means comprises a Fresnel zone plate.
6. Apparatus according to any of claims 2-5 wherein the imaging means is at least partially incorporated within the periodic diffraction means.
7. Apparatus according to any of claims 2-6 wherein a masking region is provided between the imaging means and the periodic diffraction means.
8. Apparatus according to any preceding claim wherein the first and second detecting means are provided on a single detecting unit.
9. Apparatus according to claim 8 wherein the second detecting means is at least partly incorporated within the first detecting means.
10. Apparatus according to any preceding claim wherein a single light source is used for the incremental pattern and the reference mark.
11. Apparatus according to any preceding claim wherein the imaging means, periodic diffraction means, first and second detecting means and a light source are disposed in a single plane.
12. Apparatus according to claim 11 wherein the plane is perpendicular to the direction of the scale.
PCT/GB2005/002421 2004-06-21 2005-06-21 Scale reading apparatus WO2005124282A2 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
JP2007517439A JP4932706B2 (en) 2004-06-21 2005-06-21 Scale reader
EP05758458.3A EP1766334B2 (en) 2004-06-21 2005-06-21 Scale reading apparatus
US11/629,853 US7659992B2 (en) 2004-06-21 2005-06-21 Scale reading apparatus

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB0413710.5A GB0413710D0 (en) 2004-06-21 2004-06-21 Scale reading apparatus
GB0413710.5 2004-06-21

Publications (2)

Publication Number Publication Date
WO2005124282A2 true WO2005124282A2 (en) 2005-12-29
WO2005124282A3 WO2005124282A3 (en) 2006-03-23

Family

ID=32750195

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2005/002421 WO2005124282A2 (en) 2004-06-21 2005-06-21 Scale reading apparatus

Country Status (6)

Country Link
US (1) US7659992B2 (en)
EP (1) EP1766334B2 (en)
JP (1) JP4932706B2 (en)
CN (1) CN100543424C (en)
GB (1) GB0413710D0 (en)
WO (1) WO2005124282A2 (en)

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008083029A (en) * 2006-08-29 2008-04-10 Sharp Corp Optical encoder and electronic device using it
WO2008084246A1 (en) 2007-01-11 2008-07-17 Renishaw Plc A sample positioning apparatus
WO2010116145A2 (en) * 2009-04-08 2010-10-14 Renishaw Plc Position encoder apparatus
US8141265B2 (en) 2008-06-17 2012-03-27 Renishaw Plc Scale track
US8173951B2 (en) 2008-09-19 2012-05-08 Mitutoyo Corporation Optical encoder comprising a main and reference light receiving portions with a three-phase signal generation for detecting displacement and direction of displacement of an incremental grating track
WO2015049172A1 (en) 2013-10-01 2015-04-09 Renishaw Plc Position measurement encoder
WO2015049175A1 (en) 2013-10-01 2015-04-09 Renishaw Plc Method of manufacturing an electronic component
WO2015049173A1 (en) 2013-10-01 2015-04-09 Renishaw Plc Reference mark detector arrangement
US9057630B2 (en) 2008-04-21 2015-06-16 Renishaw Plc Metrological scale
US9201313B2 (en) 2011-11-09 2015-12-01 Zygo Corporation Compact encoder head for interferometric encoder system
US9746348B2 (en) 2011-11-09 2017-08-29 Zygo Corporation Double pass interferometric encoder system
US9952068B2 (en) 2012-12-20 2018-04-24 Renishaw Plc Optical element
US10132657B2 (en) 2009-04-08 2018-11-20 Renishaw Plc Position encoder apparatus
EP3623769A1 (en) 2018-09-12 2020-03-18 Renishaw PLC Measurement device
EP3663723A1 (en) 2018-12-04 2020-06-10 Renishaw PLC Encoder apparatus
US10823587B2 (en) 2013-10-01 2020-11-03 Renishaw Plc Measurement encoder
DE102015016780B4 (en) * 2015-01-21 2021-05-12 Mitutoyo Corporation Encoder
WO2021094456A1 (en) 2019-11-15 2021-05-20 Renishaw Plc Position measurement device
WO2021094457A1 (en) 2019-11-15 2021-05-20 Renishaw Plc Encoder apparatus
EP4390328A1 (en) 2022-12-21 2024-06-26 Renishaw plc Encoder apparatus
EP4390329A1 (en) 2022-12-20 2024-06-26 Renishaw PLC Encoder apparatus
EP4390325A1 (en) 2022-12-20 2024-06-26 Renishaw PLC Encoder apparatus
US12072216B2 (en) 2019-11-15 2024-08-27 Renishaw Plc Encoder apparatus and readhead

Families Citing this family (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101061371A (en) * 2004-11-22 2007-10-24 皇家飞利浦电子股份有限公司 Optical system for detecting motion of a body
JP2011059055A (en) * 2009-09-14 2011-03-24 Mitsutoyo Corp Photoelectric encoder
JP5391115B2 (en) * 2010-03-18 2014-01-15 株式会社ミツトヨ Photoelectric encoder
KR20140039245A (en) 2011-07-06 2014-04-01 레니쇼우 피엘씨 Method of manufacture and apparatus therefor
JP6818550B2 (en) 2013-11-05 2021-01-20 レニショウ パブリック リミテッド カンパニーＲｅｎｉｓｈａｗ Ｐｕｂｌｉｃ Ｌｉｍｉｔｅｄ Ｃｏｍｐａｎｙ Position measurement encoder calibration
WO2015078860A1 (en) 2013-11-26 2015-06-04 Renishaw Plc Metrological scale
JP6694722B2 (en) * 2016-02-12 2020-05-20 株式会社東京精密 Optical encoder and its origin determination method
DE102020134604B4 (en) 2020-12-22 2022-07-14 Smaract Gmbh Device and method for position determination
US20240085220A1 (en) 2021-02-09 2024-03-14 Renishaw Plc Disc scale member offset determination
EP4134633A1 (en) 2021-08-12 2023-02-15 Renishaw PLC Position encoder apparatus
EP4384778A1 (en) 2021-08-12 2024-06-19 Renishaw PLC Position encoder apparatus
EP4390326A1 (en) 2022-12-20 2024-06-26 Renishaw PLC Encoder apparatus
EP4390327A1 (en) 2022-12-20 2024-06-26 Renishaw PLC Encoder apparatus
EP4414664A1 (en) 2023-02-09 2024-08-14 Renishaw PLC Rotary encoder apparatus

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6198534B1 (en) 1997-08-07 2001-03-06 Johannes Heidenhain Gmbh Scanning unit for an optical position measuring system

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8432574D0 (en) * 1984-12-22 1985-02-06 Renishaw Plc Opto-electronic scale-reading apparatus
JPH0389113A (en) * 1989-08-31 1991-04-15 Copal Co Ltd Optical displacement detecting apparatus
JP3089055B2 (en) * 1991-08-14 2000-09-18 日本電産コパル株式会社 Optical displacement detector
US5390022A (en) * 1992-04-07 1995-02-14 Canon Kabushiki Kaisha Displacement information detection apparatus for receiving a divergent light beam
JP3005131B2 (en) * 1992-12-28 2000-01-31 キヤノン株式会社 Displacement detector
GB9926574D0 (en) 1999-11-11 2000-01-12 Renishaw Plc Absolute position measurement
GB0103582D0 (en) 2001-02-14 2001-03-28 Renishaw Plc Position determination system
GB0109057D0 (en) 2001-04-11 2001-05-30 Renishaw Plc Absolute postition measurement
US7002137B2 (en) 2001-08-30 2006-02-21 Gsi Lumonics Corporation Reference point talbot encoder

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6198534B1 (en) 1997-08-07 2001-03-06 Johannes Heidenhain Gmbh Scanning unit for an optical position measuring system

Cited By (36)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008083029A (en) * 2006-08-29 2008-04-10 Sharp Corp Optical encoder and electronic device using it
WO2008084246A1 (en) 2007-01-11 2008-07-17 Renishaw Plc A sample positioning apparatus
US8254022B2 (en) 2007-01-11 2012-08-28 Renishaw Plc Sample positioning stage and method of operation
US9057630B2 (en) 2008-04-21 2015-06-16 Renishaw Plc Metrological scale
US9764350B2 (en) 2008-04-21 2017-09-19 Renishaw Plc Metrological scale
US8141265B2 (en) 2008-06-17 2012-03-27 Renishaw Plc Scale track
US8173951B2 (en) 2008-09-19 2012-05-08 Mitutoyo Corporation Optical encoder comprising a main and reference light receiving portions with a three-phase signal generation for detecting displacement and direction of displacement of an incremental grating track
WO2010116145A2 (en) * 2009-04-08 2010-10-14 Renishaw Plc Position encoder apparatus
WO2010116145A3 (en) * 2009-04-08 2010-12-16 Renishaw Plc Position encoder apparatus
US8742956B2 (en) 2009-04-08 2014-06-03 Renishaw Plc Position encoder apparatus
US10132657B2 (en) 2009-04-08 2018-11-20 Renishaw Plc Position encoder apparatus
US9201313B2 (en) 2011-11-09 2015-12-01 Zygo Corporation Compact encoder head for interferometric encoder system
US9746348B2 (en) 2011-11-09 2017-08-29 Zygo Corporation Double pass interferometric encoder system
EP3564628A1 (en) 2012-12-20 2019-11-06 Renishaw PLC Optical element
US10768026B2 (en) 2012-12-20 2020-09-08 Renishaw Plc Optical element
US9952068B2 (en) 2012-12-20 2018-04-24 Renishaw Plc Optical element
WO2015049175A1 (en) 2013-10-01 2015-04-09 Renishaw Plc Method of manufacturing an electronic component
US10823587B2 (en) 2013-10-01 2020-11-03 Renishaw Plc Measurement encoder
WO2015049173A1 (en) 2013-10-01 2015-04-09 Renishaw Plc Reference mark detector arrangement
US10281301B2 (en) 2013-10-01 2019-05-07 Renishaw Plc Reference mark detector arrangement
WO2015049172A1 (en) 2013-10-01 2015-04-09 Renishaw Plc Position measurement encoder
DE102015016780B4 (en) * 2015-01-21 2021-05-12 Mitutoyo Corporation Encoder
EP3623769A1 (en) 2018-09-12 2020-03-18 Renishaw PLC Measurement device
WO2020053566A1 (en) 2018-09-12 2020-03-19 Renishaw Plc Measurement device
EP3663723A1 (en) 2018-12-04 2020-06-10 Renishaw PLC Encoder apparatus
WO2020115464A1 (en) 2018-12-04 2020-06-11 Renishaw Plc Encoder apparatus
WO2021094456A1 (en) 2019-11-15 2021-05-20 Renishaw Plc Position measurement device
WO2021094457A1 (en) 2019-11-15 2021-05-20 Renishaw Plc Encoder apparatus
US12038310B2 (en) 2019-11-15 2024-07-16 Renishaw Plc Encoder apparatus with readhead having circuit board and a folded sheet-metal structure to support a light emitting element
US12072216B2 (en) 2019-11-15 2024-08-27 Renishaw Plc Encoder apparatus and readhead
EP4390329A1 (en) 2022-12-20 2024-06-26 Renishaw PLC Encoder apparatus
EP4390325A1 (en) 2022-12-20 2024-06-26 Renishaw PLC Encoder apparatus
WO2024134152A1 (en) 2022-12-20 2024-06-27 Renishaw Plc Encoder apparatus
WO2024134155A1 (en) 2022-12-20 2024-06-27 Renishaw Plc Encoder apparatus
WO2024134156A1 (en) 2022-12-20 2024-06-27 Renishaw Plc Encoder apparatus
EP4390328A1 (en) 2022-12-21 2024-06-26 Renishaw plc Encoder apparatus

Also Published As

Publication number Publication date
EP1766334B1 (en) 2014-07-02
CN100543424C (en) 2009-09-23
EP1766334B2 (en) 2021-10-06
JP2008503745A (en) 2008-02-07
GB0413710D0 (en) 2004-07-21
EP1766334A2 (en) 2007-03-28
JP4932706B2 (en) 2012-05-16
US20080013105A1 (en) 2008-01-17
CN1973185A (en) 2007-05-30
WO2005124282A3 (en) 2006-03-23
US7659992B2 (en) 2010-02-09

Similar Documents

Publication Publication Date Title
US7659992B2 (en) Scale reading apparatus
US7825368B2 (en) Absolute position length-measurement type encoder
EP2535686B1 (en) Optical encoder including displacement sensing normal to the encoder scale grating surface
EP0770850B1 (en) Displacement information detection apparatus
US7061624B2 (en) Grating interference type optical encoder
US7141780B2 (en) Position determination system for determining the position of one relatively moveable part relative to another relatively movable part
US5448358A (en) Optical apparatus and displacement-information measuring apparatus using the same
US20160231143A1 (en) Position measurement encoder
US9933284B2 (en) Multi-track absolute encoder
JP4337415B2 (en) Encoder
US5038491A (en) Scale for use for measurement of the displacement of an object to be examined, and displacement measuring apparatus
US5497226A (en) Quadrature diffractive encoder
CN108931190B (en) Displacement detection device
JP2670457B2 (en) Zero position detector
KR102027163B1 (en) Measuring device and method for triangulation measurement
SU932220A1 (en) Device for registering object displacement
WO2008074998A1 (en) Phase constrast encoding
JPH03115809A (en) Encoder
JP3013467B2 (en) Laser interference encoder
CA2298512A1 (en) High resolution incremental optical encoder

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A2

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BW BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE EG ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KM KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NA NG NI NO NZ OM PG PH PL PT RO RU SC SD SE SG SK SL SM SY TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A2

Designated state(s): BW GH GM KE LS MW MZ NA SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LT LU MC NL PL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
WWE Wipo information: entry into national phase

Ref document number: 11629853

Country of ref document: US

WWE Wipo information: entry into national phase

Ref document number: 200580020409.9

Country of ref document: CN

WWE Wipo information: entry into national phase

Ref document number: 2007517439

Country of ref document: JP

NENP Non-entry into the national phase

Ref country code: DE

WWW Wipo information: withdrawn in national office

Ref document number: DE

WWE Wipo information: entry into national phase

Ref document number: 340/DELNP/2007

Country of ref document: IN

WWE Wipo information: entry into national phase

Ref document number: 2005758458

Country of ref document: EP

WWP Wipo information: published in national office

Ref document number: 2005758458

Country of ref document: EP

WWP Wipo information: published in national office

Ref document number: 11629853

Country of ref document: US