EP0125068A2
Expired / Lapsed
EP
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Optical position determining apparatus
Assignee: WELLS-GARDNER ELECTRONICS CORP
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Filing: 1984-04-25
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Granted: —
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Expires: 2004-04-25
Abstract
Abstract An optical position indicating apparatus comprising a light source 30, detector means 28 for detecting the presence of light and producing an electrical output in response to it, reflecting means 16 for reflecting light fromthe light source 30 across a target zone 14, and retroreflecting means 18, 20, 24 for reflecting light incident upon their back along a path substantially coincident with its path of incidence. The retroreflecting means comprise a plurality of retroreflective assemblies 18, 20, 24 disposed around the target zone and limiting means 49 limitthe detector means 28to a finite viewing range so that rotation of the detector means 28 scans the target zone 14. The detector means 28 is capable of measuring angular displacement from a reference position so that the presence of an opaque object within the target zone registers upon the detector means as a plurality of shadows thereby resulting in the absence of an electrical output from the detector means for each of the plurality of shadows. The location of the opaque object 59 in two dimensions within the target zone 14 is then determined from the angular displacements of the plurality of shadows, for example by geometric calculation.
Inventors
- 👤 James L. Griffin
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 23:59
CPC Classifications
G; G06; G06F; G06F3/00; G06F3/01; G06F3/03; G06F3/041; G06F3/042; G06F3/0421; G06F3/0423
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
183 words
An optical position indicating apparatus comprising a light source (30), detector means (28) for detecting the presence of light and producing an electrical output in response to it and reflecting means (16) for reflecting light from the light source (30) across a target zone (14) the detector means (28) being rotatable to effect scanning of the target zone (14), characterised in that the apparatus also includes retroreflecting means for reflecting light incident upon it along a path substantially coincident with its path of incidence, the retroreflecting means comprising a plurality of retroreflective assemblies (18, 20, 22, 24), the reflecting means (16) and the plurality of retroreflective assemblies (18, 20, 22, 24) being substantially disposed about the target zone, and limiting means (49) for limiting the detector means to a finite viewing range, the presence of an opaque object within the target zone (14) registering upon the detector means (28) as a plurality of shadows, and the detector means (28) scanning the target zone (14) to enable the location of the opaque object in two dimensions within the target zone (14) to be determined.
Claim 2
Dependent Claim
183 words
An optical position indicating apparatus comprising a light source (30), detector means (28) for detecting the presence of light and producing an electrical output in response to it and reflecting means (16) for reflecting light from the light source (30) across a target zone (14) the detector means (28) being rotatable to effect scanning of the target zone (14), characterised in that the apparatus also includes retroreflecting means for reflecting light incident upon it along a path substantially coincident with its path of incidence, the retroreflecting means comprising a plurality of retroreflective assemblies (18, 20, 22, 24), the reflecting means (16) and the plurality of retroreflective assemblies (18, 20, 22, 24) being substantially disposed about the target zone, and limiting means (49) for limiting the detector means to a finite viewing range, the presence of an opaque object within the target zone (14) registering upon the detector means (28) as a plurality of shadows, and the detector means (28) scanning the target zone (14) to enable the location of the opaque object in two dimensions within the target zone (14) to be determined.
Claim 3
Dependent Claim
48 words
An optical position indicating apparatus according to claim 1, which also includes light directing means (26) for initially directing light from the light source (30) across the target zone (14) and for directing return light received after passage across the target zone (14) to the detector means (28).
Claim 4
Dependent Claim
20 words
An optical position indicating apparatus according to claim 2, in which the light directing means is a beam splitter (26).
Claim 5
Dependent Claim
58 words
An optical position indicating apparatus according to any one of the preceding claims, in which the plurality of retroreflective assemblies comprises a first assembly comprising a first strip (18) of retroreflective material, a second assembly comprising a second strip (22) of retroreflective material, and a third assembly comprising a plurality of strips (24) of retroreflective material in echelon.
Claim 6
Dependent Claim
121 words
An optical position indicating apparatus according to claim 4, in which the target zone (14) is substantailly rectangular, the light source (30) and the detector means (28) being positioned in a first corner of the target zone (14), the reflecting means (16) defining a first side of the target zone terminating at a second corner of the target zone (14), the second corner being diagonally opposite the first corner, the first retroreflective assembly (18) defining a second side of the target zone (14) opposite to the first side, and the second retroreflective assembly (20) defining a third side of the target zone (14) extending between the first and sr-cond sides and remote from the source (30) and detector ( ) .
Claim 7
Dependent Claim
154 words
An optical position indicating apparatus according to claim 5, in which the second (20) and the third (24) retroreflecting means extending side-by-side along the third side of the target zone (14) and in which the reflecting means (16) the first retroreflective assembly (18) and the second retroreflective assembly (22) each has a first edge and a second edge and the third retroreflective assembly (24) has a plurality of first edges and a plurality of second edges; the first edges of the reflecting means (16), the first retroreflecting assembly (18) and the second retroreflective assembly (22) all being substantially coplanar in a target plane; the second edges of the reflecting means (16), the first retroreflective assembly (18) and the third retroreflective assembly (24) all being substantially coplanar in a target plane; and the second edges of the second retroreflective assembly (22) and the first edges of the third retroreflective assembly (24) being adjacent one another.
Claim 8
Dependent Claim
34 words
An optical position indicating apparatus according to any one of claims 4 to 6, in which the first retroreflective assembly (18) is curved to receive light reflected from the reflecting means (16) substantially normally.
Claim 9
Dependent Claim
33 words
An optical position indicating apparatus according to any one of claims 4 to 7, in which the second retroreflective assembly (22) is curved to receive light from the light source (30) substantially normally.
Claim 10
Dependent Claim
43 words
An optical position indicating apparatus according to any one of claims 4 to 8, in which the third retroreflective assembly (24) is positioned to present a plurality of retroreflecting surfaces each of which receives light reflected from the reflecting means (16) substantially normally.
Claim 11
Dependent Claim
94 words
An optical position indicating apparatus according to any one of the preceding claims, in which the detector means (28) includes means for measuring its angular displacement from a reference position, so that where an opaque object located within the target zone (14) produces a plurality of shadows as the detector means (28) scans the target zone (14), the resulting absence of an electrical output for each of the plurality of shadows at particular angular displacements of the detector means (28) enables the position of the object in the target zone (14) to be determined.
References Cited (Backward Citations)
No citation records indexed.
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