EP0100243A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Position sensor
Assignee: Adrian March Research Ltd
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Filing: 1983-07-28
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Granted: —
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Expires: 2003-07-28
Abstract
Abstract A position sensor has a scale consisting of tracks of indicia (26, 28, 30, 32, 38, 40) in the form of bar patterns acting on a detector (24) having a two-dimensional array of sensitive elements. One track (38) has indicia with a pitch slightly greater than the pitch of the sensitive elements and another track (40) has indicia with a pitch slightly less than the pitch of the sensitive elements. The other tracks (26, 28, 30, 32) provide a coarse determination of the position of the scale relative to the detector (24) whilst the first two tracks (38, 40) provide resolution of the position to less than the pitch of the sensitive elements. There is sufficient redundant information to enable accurate position detection even if there are optical or electrical perturbations in the detection of individual indicia.
Inventors
- 👤 Adrian Anthony Cecil March
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 16:29
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/26; G01D5/32; G01D5/34; G01D5/36; G01D5/38; H; H03; H03M; H03M1/00; H03M1/06; H03M1/0617; H03M1/0675; H03M1/12; H03M1/22; H03M1/24; H03M1/26
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
169 words
A position sensor comprising a detector (2) having a plurality of sensitive elements (6) . adjacent sensitive elements (6) having a predetermined pitch therebetween; at least one scale having at least one track (26,28,30,32,38,40) of indicia, the or each scale being movable relative to the detector (2), adjacent indicia in at least part of the at least one track (38,40) having a pitch less than twice but not equal to the pitch of the sensitive elements (6) and acting on the sensitive elements (6) of at least part of the detector (2), each sensitive element (6) being adapted to detect the overlap of that sensitive element (6) and a corresponding one of the indicia and generate an output in dependence upon that overlap; and means for processing the outputs of the sensitive elements (6) to determine the relative positions of the detector (2) and the scale; characterized in that: the plurality of sensitive elements (6) is arranged in an array (4,24) of sensitive elements (6) extending in two dimensions.
Claim 2
Dependent Claim
169 words
A position sensor comprising a detector (2) having a plurality of sensitive elements (6) . adjacent sensitive elements (6) having a predetermined pitch therebetween; at least one scale having at least one track (26,28,30,32,38,40) of indicia, the or each scale being movable relative to the detector (2), adjacent indicia in at least part of the at least one track (38,40) having a pitch less than twice but not equal to the pitch of the sensitive elements (6) and acting on the sensitive elements (6) of at least part of the detector (2), each sensitive element (6) being adapted to detect the overlap of that sensitive element (6) and a corresponding one of the indicia and generate an output in dependence upon that overlap; and means for processing the outputs of the sensitive elements (6) to determine the relative positions of the detector (2) and the scale; characterized in that: the plurality of sensitive elements (6) is arranged in an array (4,24) of sensitive elements (6) extending in two dimensions.
Claim 3
Dependent Claim
130 words
A position sensor according to claim 1 having at least two tracks (26,28,30,32,38,40) of indicia, the indicia in at least part of a first track (38) having a pitch less than twice but greater than the pitch of the sensitive elements (6), and the indicia in a second track (40) having a pitch less than the pitch of the sensitive elements (6), the sensitive elements (6) detecting the overlap of indicia of the first track (38) generating outputs forming a first signal envelope and the sensitive elements (6) detecting the overlap of the indicia of the second track (40) generating outputs forming a second signal envelope, the processing means determining the relative position of the detector and the scale from the phase difference between the first and second signal envelopes.
Claim 4
Dependent Claim
55 words
A position sensor according to claim 2, wherein the pitch of the indicia in the first track (38) is times the pitch of the sensitive elements (6), and the pitch of the indicia in the second track (40) is times the pitch of the sensitive elements (6), where n is an integer greater than 2.
Claim 5
Dependent Claim
85 words
A position sensor according to claim 2 or claim 3 wherein the processing means is adapted to compare the first signal envelope with a third signal envelope determined by interpolation between the outputs of the sensitive elements (6) generating signals forming the second signal envelope shifted in phase to the nearest sensitive element (6) either side of the first signal envelope, thereby to determine the phase difference between the first and second signal envelopes to a fractional part of the pitch of the sensitive elements.
Claim 6
Dependent Claim
35 words
A position sensor according to any one of the preceding claims having a further track of indicia (26,28,30,32) with the pitch of those indicia being random multiples of the pitch of the sensitive elements (6).
Claim 7
Dependent Claim
58 words
A position sensor according to any one of the preceding claims wherein the scale is an optical image of a pattern of markings on a first body, and the detector is fixed relative to a second body, thereby to determine the relative positions of the first and second bodies from the relative positions of the scale and detector.
Claim 8
Dependent Claim
15 words
A position sensor according to claim 6, wherein the optical image is a transmissive image.
Claim 9
Dependent Claim
15 words
A position sensor according to claim 6, wherein the optical image is a reflective image.
Claim 10
Dependent Claim
30 words
A position sensor according to any one of the preceding claims wherein the or each track is a circle of indicia, and the detector has concentric rings of sensing elements.
Claim 11
Dependent Claim
41 words
A position sensor according to any one of the preceding claims, having at least two scales, each scale being independently movable relative to the detector, thereby to determine the relative positions of the scales independent of the position of the detector.
References Cited (Backward Citations)
No citation records indexed.
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