US5064290A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Opto-electronic scale-reading apparatus wherein phase-separated secondary orders of diffraction are generated
Assignee: Renishaw PLC
•
Filing: 1990-04-12
•
Granted: 1991-11-12
•
Expires: 2010-04-12
Abstract
Abstract Apparatus for generating a quadrature signal for the purpose of determining the direction in which the scale is being read. There is provided a primary grating means defining spaced lines and adapted for generating orders of diffraction, secondary grating means defining spaced lines arranged at an angle to those of the primary grating means thereby to separate said orders of diffraction into differing phases, and tertiary grating means movable together with the secondary grating means relative to said primary grating means and adapted for detecting the respective said phases and for generating correspondingly phased light modulations which are detected by respective transducers connected to a quadrature-forming circuit.
Inventors
- 👤 David R. McMurtry
- 👤 William F. N. Stephens
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 17:59
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/26; G01D5/32; G01D5/34; G01D5/36; G01D5/38
Claims Analysis
Total Claims: 57
Claim 1
Independent Claim
188 words
Opto-electronic scale reading apparatus comprising: first grating means defining a scale; a read head, said read head being displaceable relative to the scale, second and third grating means provided on the read head, said first, second and third grating means each having a periodic structure defined by spaced lines; a light source provided on the read head for illuminating one of said first and second grating means, the other of said first and second grating means interacting with light transmitted through said one of said first and second grating means for generating a periodic light pattern in the plane of the third grating means, said periodic light pattern having movement relative to said third grating means in accordance with said displacement thereby generating a corresponding light modulation; and phase-separating means for separating said modulation into a plurality of phases comprising fourth grating means positioned between said third and said one of the first and second grating means for generating a plurality of said periodic light patterns, said periodic light patterns cooperating with said third grating means to generate a plurality of said light modulations having a phase-shifted relationship.
Claim 2
Dependent Claim
188 words
Opto-electronic scale reading apparatus comprising: first grating means defining a scale; a read head, said read head being displaceable relative to the scale, second and third grating means provided on the read head, said first, second and third grating means each having a periodic structure defined by spaced lines; a light source provided on the read head for illuminating one of said first and second grating means, the other of said first and second grating means interacting with light transmitted through said one of said first and second grating means for generating a periodic light pattern in the plane of the third grating means, said periodic light pattern having movement relative to said third grating means in accordance with said displacement thereby generating a corresponding light modulation; and phase-separating means for separating said modulation into a plurality of phases comprising fourth grating means positioned between said third and said one of the first and second grating means for generating a plurality of said periodic light patterns, said periodic light patterns cooperating with said third grating means to generate a plurality of said light modulations having a phase-shifted relationship.
Claim 3
Dependent Claim
40 words
Apparatus according to claim 1 wherein the respective lines of the first, second and third grating means extend in a common direction, and the fourth grating means is defined by lines extending at an angle α to the common direction.
Claim 4
Dependent Claim
19 words
Apparatus according to claim 2 wherein the fourth grating means is situated between the second and third grating means.
Claim 5
Dependent Claim
19 words
Apparatus according to claim 2 wherein the fourth grating means is situated between the first and second grating means.
Claim 6
Dependent Claim
14 words
Apparatus according to claim 2 wherein the fourth grating means comprises a phase grating.
Claim 7
Dependent Claim
48 words
Apparatus according to claim 2 wherein said angle is tan α=ΔG/(G×Δα) wherein α=said angle, G=the distance between the fourth grating means and the one of the first, second and third grating means nearest thereto. Δα=a manufacturing tolerance for the angle α. ΔG=a manufacturing tolerance for the distance G.
Claim 8
Dependent Claim
13 words
Apparatus according to claim 2 wherein said angle is less than 90 degrees.
Claim 9
Dependent Claim
37 words
Apparatus according to claim 1 wherein the respective lines of the first, second and third grating means extend in a common direction, and the fourth grating means is defined by lines extending parallel to the common direction.
Claim 10
Dependent Claim
64 words
Apparatus according to claim 1 wherein said first and second grating means, and said fourth grating means co-operate for generating a set of primary diffraction orders and for generating from each of said primary orders a set of secondary diffraction orders; and the apparatus comprises means for collecting like orders of said sets of secondary orders, and means for detecting said collected like orders.
Claim 11
Dependent Claim
30 words
Apparatus according to claim 1 wherein said grating means are arranged for the light from said source to pass in succession through said second, first, fourth and third grating means.
Claim 12
Dependent Claim
77 words
Apparatus according to claim 10 wherein said second and first grating means co-operate for generating a set of primary diffraction orders and said fourth grating means is positioned for generating from each of said primary orders a set of secondary diffraction orders; and wherein the apparatus further comprises collecting means for collecting those secondary orders of each of the respective sets of secondary orders which have the same direction, and means for detecting respective collected said orders.
Claim 13
Dependent Claim
28 words
Apparatus according to claim 11 wherein said collecting means comprise a decollimating lens means for focusing said secondary orders having the same direction into a respective common focus.
Claim 14
Dependent Claim
14 words
Apparatus according to claim 12 comprising transducer means for detecting the respective said foci.
Claim 15
Dependent Claim
30 words
Apparatus according to claim 1 wherein said grating means are arranged for the light from said source to pass in succession through said first, second, fourth and third grating means.
Claim 16
Dependent Claim
76 words
Apparatus according to claim 14 wherein said first and second grating means co-operate for generating a set of primary diffraction orders, and said fourth grating means is positioned for generating from each of said primary orders a set of secondary diffraction orders; and wherein the apparatus further comprises collecting means for collecting those orders of each of the respective sets of secondary orders which have the same direction, and means for detecting respective collected said orders.
Claim 17
Dependent Claim
28 words
Apparatus according to claim 15 wherein said collecting means comprise a decollimating lens means for focusing said secondary orders having the same direction into a respective common focus.
Claim 18
Dependent Claim
30 words
Apparatus according to claim 1 wherein said grating means are arranged for the light from said source to pass in succession through said first, fourth, second and third grating means.
Claim 19
Dependent Claim
76 words
Apparatus according to claim 17 wherein said first and fourth grating means co-operate for generating a set of primary diffraction orders, and said second grating means is positioned for generating from each of said primary orders a set of second diffraction orders; and wherein the apparatus further comprises collecting means for collecting those orders of each of the respective sets of secondary orders which have the same direction, and means for detecting respective collected said orders.
Claim 20
Dependent Claim
28 words
Apparatus according to claim 18 wherein said collecting means comprise a decollimating lens means for focussing said secondary orders having the same direction into a respective common focus.
Claim 21
Dependent Claim
30 words
Apparatus according to claim 1 wherein said grating means are arranged for the light from said source to pass in succession through said second, fourth, first and third grating means.
Claim 22
Dependent Claim
76 words
Apparatus according to claim 20 wherein said second and fourth grating means co-operate for generating a set of primary diffraction orders, and said first grating means is positioned for generating from each of said primary orders a set of secondary diffraction orders; and wherein the apparatus further comprises collecting means for collecting those orders of each of the respective sets of secondary orders which have the same direction, and means for detecting respective collected said orders.
Claim 23
Dependent Claim
28 words
Apparatus according to claim 21 wherein said collecting means comprise a decollimating lens means for focussing said secondary orders having the same direction into a respective common focus.
Claim 24
Dependent Claim
191 words
Opto-electronic scale-reading apparatus comprising: first grating means defining a scale; a read head, said read head being displaceable relative to the scale; second grating means provided on the read head, said first and second grating means each having a periodic structure defined by spaced lines; a source of coherent light provided on the read head for illuminating one of said first and second grating means for generating interference fringes in the plane of the other one of said first and second grating means, said interference fringes having movement relative to said other one of said first and second grating means in accordance with said displacement thereby to generate a corresponding light modulation and; phase-separating means for separating said modulation into a plurality of phases comprising third grating means positioned between said first and second grating means and lying in a plane parallel to the plane of one of said first and second grating means, the respective lines of said first and second grating means lying in a common direction, and said third grating means being defined by lines lying at an angle to said common direction thereby effecting said phase separation.
Claim 25
Dependent Claim
191 words
Opto-electronic scale-reading apparatus comprising: first grating means defining a scale; a read head, said read head being displaceable relative to the scale; second grating means provided on the read head, said first and second grating means each having a periodic structure defined by spaced lines; a source of coherent light provided on the read head for illuminating one of said first and second grating means for generating interference fringes in the plane of the other one of said first and second grating means, said interference fringes having movement relative to said other one of said first and second grating means in accordance with said displacement thereby to generate a corresponding light modulation and; phase-separating means for separating said modulation into a plurality of phases comprising third grating means positioned between said first and second grating means and lying in a plane parallel to the plane of one of said first and second grating means, the respective lines of said first and second grating means lying in a common direction, and said third grating means being defined by lines lying at an angle to said common direction thereby effecting said phase separation.
Claim 26
Dependent Claim
72 words
Opto-electric scale-reading apparatus according to claim 23 wherein said light source and said one of the first and second grating means co-operate for forming a set of primary diffraction orders, said third grating means generates from each of said primary orders a set of secondary diffraction orders; and the apparatus comprises means for collecting like orders of each of said sets of secondary orders, and means for detecting said collected like orders.
Claim 27
Dependent Claim
30 words
Opto-electronic scale-reading apparatus according to claim 24 wherein said collecting means comprises a decollimating leans means for focussing said secondary orders having the same direction into a respective common focus.
Claim 28
Dependent Claim
16 words
Opto-electronic scale-reading apparatus according to claim 25 comprising transducer means for detecting the respective said foci.
Claim 29
Dependent Claim
84 words
Opto-electronic scale-reading apparatus comprising a scale and a readhead, the readhead having a single analyser grating; illuminating means for illuminating the scale with a beam of light and for generating a periodic light pattern in the plane of said single analyser grating, and a light modulation upon relative movement of the scale and the readhead; and splitting means for generating a plurality of said periodic light patterns thereby providing at said single analyser grating a plurality of said light modulations in a phase-shifted relationship.
Claim 30
Dependent Claim
84 words
Opto-electronic scale-reading apparatus comprising a scale and a readhead, the readhead having a single analyser grating; illuminating means for illuminating the scale with a beam of light and for generating a periodic light pattern in the plane of said single analyser grating, and a light modulation upon relative movement of the scale and the readhead; and splitting means for generating a plurality of said periodic light patterns thereby providing at said single analyser grating a plurality of said light modulations in a phase-shifted relationship.
Claim 31
Dependent Claim
16 words
An apparatus according to claim 27 wherein said splitting means is provided by an auxiliary grating.
Claim 32
Dependent Claim
20 words
An apparatus according to claim 28 wherein the illuminating means comprises a beam of non-coherent light and an index grating.
Claim 33
Dependent Claim
39 words
An apparatus according to claim 28 wherein said illuminating means comprises means for generating a set of primary diffraction orders thereby generating interference fringes in the plane of the analyser grating, and the auxiliary grating generates second diffraction orders.
Claim 34
Dependent Claim
21 words
An apparatus according to claim 30 wherein the illuminating means comprises a beam of coherent light incident directly upon the scale.
Claim 35
Dependent Claim
45 words
An apparatus according to claim 30 wherein the illuminating means comprises a beam of non-coherent light and an index grating, and wherein the index grating is provided in the beam path upbeam of the scale, and the primary diffraction orders are generated by the scale.
Claim 36
Dependent Claim
46 words
An apparatus according to claim 30 wherein the illuminating means comprises a beam of non-coherent light and an index grating, and wherein the index grating is provided in the beam path upbeam of the scale, and the primary diffraction orders are generated by the index grating.
Claim 37
Dependent Claim
44 words
An apparatus according to claim 31 wherein the auxiliary grating is provided in the beam path upbeam of the scale, thereby to illuminate the scale with said secondary orders, the scale generating in respect of each said secondary order a set of primary orders.
Claim 38
Dependent Claim
54 words
An apparatus according to claim 31 wherein the auxiliary grating is provided in the beam path down beam of the scale, thereby to split said primary orders of diffraction formed at said scale into said plurality of sets, and each one of said plurality of sets corresponding to a said secondary order of diffraction.
Claim 39
Dependent Claim
45 words
An apparatus according to claim 32 wherein the auxiliary grating is provided in the beam path between the index grating and the scale, thereby to illuminate the scale with said secondary orders, the scale generating in respect of each said secondary order a primary order.
Claim 40
Dependent Claim
49 words
An apparatus according to claim 32 wherein the auxiliary grating is provided in the beam path downbeam of the scale thereby to split said primary orders of diffraction into said plurality of sets and each one of said plurality of sets corresponding to a said secondary order of diffraction.
Claim 41
Dependent Claim
49 words
An apparatus according to claim 33 wherein the auxiliary grating is provided in the beam path between the scale and the index grating, thereby to illuminate the index grating with said secondary orders, the index grating generating in respect of each said secondary order a set of primary orders.
Claim 42
Dependent Claim
50 words
An apparatus according to claim 33 wherein the auxiliary grating is provided in the beam path downbeam of the index grating thereby to split said primary orders of diffraction into said plurality of sets, and each one of said plurality of sets corresponding to a said secondary order of diffraction.
Claim 43
Dependent Claim
44 words
An apparatus according to claim 32 wherein the index grating, analyser grating and auxiliary grating each have a periodic structure defined by spaced lines, and the index grating and analyser grating are provided adjacent each other on one side of a single glass plate.
Claim 44
Dependent Claim
26 words
An apparatus according to claim 40 wherein the auxiliary grating is provided on another side of the glass plate and in register with the index grating.
Claim 45
Dependent Claim
26 words
An apparatus according to claim 40 wherein the auxiliary grating is provided on another side of the glass plate and in register with the analyser grating.
Claim 46
Dependent Claim
55 words
An apparatus according to claim 42 wherein light is incident upon the scale via an aperture provided on said another side of said plate and in register with the index grating, and is incident upon the analyser via an aperture provided on said another side of said plate and in register with the analyser grating.
Claim 47
Dependent Claim
46 words
An apparatus according to claim 43 wherein the lines of the auxiliary grating extend parallel to the lines of the analyser grating thereby to split said primary orders of diffraction into said plurality of sets, in a direction perpendicular to the lines of the analyser grating.
Claim 48
Dependent Claim
48 words
An apparatus according to claim 42 having a single aperture extending perpendicular to the direction of the lines of the index and analyser gratings and wherein the lines of the auxiliary grating extend at an angle less than 90° to the lines of the index and analyser gratings.
Claim 49
Dependent Claim
27 words
An apparatus according to claim 44 further comprising a transducer for detecting the light modulation corresponding to each one of said plurality of sets of primary orders.
Claim 50
Dependent Claim
27 words
An apparatus according to claim 45 further comprising a transducer for detecting the light modulation corresponding to each one of said plurality of sets of primary orders.
Claim 51
Dependent Claim
171 words
Opto-electronic apparatus for measuring relative displacement of two members moveable relative to each other in a measuring direction, the apparatus comprising: first, second and third grating means each defined by a series of spaced apart parallel lines extending substantially perpendicular to said measuring direction; a light source positioned to sequentially illuminate said first, second and third grating means thereby generating a periodic light pattern in the plane of the third grating means, one of said first, second and third grating means being provided by a scale connected to one of said members, and the others of said first, second, and third grating means being provided in a readhead connected to the other of the members; and splitting means provided upbeam of the third grating means for splitting said periodic light pattern into a plurality of periodic light patterns, each periodic light pattern of said plurality of light patterns being offset from each other periodic light pattern of said plurality in a direction perpendicular to the lines of said third grating means.
Claim 52
Dependent Claim
171 words
Opto-electronic apparatus for measuring relative displacement of two members moveable relative to each other in a measuring direction, the apparatus comprising: first, second and third grating means each defined by a series of spaced apart parallel lines extending substantially perpendicular to said measuring direction; a light source positioned to sequentially illuminate said first, second and third grating means thereby generating a periodic light pattern in the plane of the third grating means, one of said first, second and third grating means being provided by a scale connected to one of said members, and the others of said first, second, and third grating means being provided in a readhead connected to the other of the members; and splitting means provided upbeam of the third grating means for splitting said periodic light pattern into a plurality of periodic light patterns, each periodic light pattern of said plurality of light patterns being offset from each other periodic light pattern of said plurality in a direction perpendicular to the lines of said third grating means.
Claim 53
Dependent Claim
30 words
Apparatus according to claim 48 wherein said splitting means additionally offsets each periodic light pattern of said plurality in a direction parallel to the lines of the third grating means.
Claim 54
Dependent Claim
30 words
Apparatus according to claim 49 wherein said second grating means is provided by said scale, and said splitting means is provided by an auxiliary grating positioned downbeam of said scale.
Claim 55
Dependent Claim
25 words
Apparatus according to claim 50 wherein the lines of the auxiliary grating extend at a non-perpendicular angle to the lines of the third grating means.
Claim 56
Dependent Claim
57 words
Apparatus according to claim 50 wherein said first and third grating means are each provided by a single grating, both said single gratings being provided adjacent each other on one side of a single glass plate, and wherein said auxiliary grating is provided in register with said third grating means on another side of said glass plate.
Claim 57
Dependent Claim
36 words
Apparatus according to claim 52 having an aperture on said another side of said glass plate extending perpendicular to the lines of said third grating means, and wherein said auxiliary grating is provided in said aperture.
References Cited (Backward Citations)
GB1504691A
Cited
US4091281A
Cited
US4222633A
Cited
DE2451994A1
Cited
US4273448A
Cited
US4527056A
Cited
EP0132978A2
Cited
EP0163362A1
Cited
US4776701A
Cited
US4800547A
Cited
WO1989005440A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-11-11 | 1995-05-13 | 1995-11-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-11-11 | 1999-05-13 | 1999-11-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-11-11 | 2003-05-13 | 2003-11-12 | $7700.00 | Window Closed / Lapsed |