EP0042946A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Holographic scanner for generating scan patterns and its application to the sensing of bar code labels
Assignee: International Business Machines Corp
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Filing: 1981-05-12
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Granted: —
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Expires: 2001-05-12
Abstract
Abstract The holographic scanner includes a rotating glass disk (20) having an annular track of sectorial holographic diffraction gratings or holofacets (22) for deflecting an impinging laser (24) beam along arcuate scan lines. The beam which sweeps along these scan lines is redirected by beam folding mirrors (30), to create specific scan patterns focused in predetermined regions (36,38) adjacent a scanner window (32). Similar or dissimilar scan patterns can be generated depending upon the characteristics of the holofacets (22) and the placement of the beam folding mirrors (30). The scan patterns can be focused at different distances from the scanner window (32) to increase the size of the "gate" through which a label must pass in order to be successfully scanned. The returning light is focused by a lens (40) onto a photodetector (42) which generates an electrical signal proportional to the reflected radiation amplitude.
Inventors
- 👤 Leroy David Dickson
- 👤 Norman Joseph Woodland
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 10:31
CPC Classifications
G; G06; G06K; G06K7/00; G06K7/10; G06K7/10544; G06K7/10821; G06K7/10861; G06K7/10871; G02; G02B; G02B26/00; G02B26/08; G02B26/10; G02B26/106; G06K2207/00; G06K2207/1013
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
155 words
Holographic scanner for generating scan patterns characterized in that it comprises : a circular member having beam-deflecting holograms arranged in segments of a multi-segment annular track, said holograms being divided into a plurality of sets with each hologram in each set being capable of focussing an incident collimated beam of radiation at a predetermined distance from the hologram; means for directing a collimated beam of radiation along a predetermined path intersecting with the annular track; means for rotating said circular member about a fixed axis to move each hologram segment through the path of the collimated beam, the relative movement between each hologram segment and the beam causing the beam to be deflected along a predetermined scan line as a function of the segment characteristics; and an optical system for redirecting the deflected beam to form a number of scan patterns equal to the number of sets of holograms, said scan patterns being spatially displaced.
Claim 2
Dependent Claim
155 words
Holographic scanner for generating scan patterns characterized in that it comprises : a circular member having beam-deflecting holograms arranged in segments of a multi-segment annular track, said holograms being divided into a plurality of sets with each hologram in each set being capable of focussing an incident collimated beam of radiation at a predetermined distance from the hologram; means for directing a collimated beam of radiation along a predetermined path intersecting with the annular track; means for rotating said circular member about a fixed axis to move each hologram segment through the path of the collimated beam, the relative movement between each hologram segment and the beam causing the beam to be deflected along a predetermined scan line as a function of the segment characteristics; and an optical system for redirecting the deflected beam to form a number of scan patterns equal to the number of sets of holograms, said scan patterns being spatially displaced.
Claim 3
Dependent Claim
33 words
Holographic scanner as defined in claim 1 wherein the holograms are divided into two sets to generate two scan patterns in different regions relative to the plane of rotation of said circular member.
Claim 4
Dependent Claim
32 words
Holographic scanner as defined in claim 2 wherein the holograms are divided into two sets to generate two similar scan patterns having corresponding lines focused at different distances from said circular member.
Claim 5
Dependent Claim
17 words
Holographic scanner as defined in claim 2 wherein dissimilar scan patterns are generated in the two regions.
Claim 6
Dependent Claim
28 words
Holographic scanner as defined in any one of claims 2, 3 or 4 wherein said first and second sets of holograms occupy adjacent sectors on said circular member.
Claim 7
Dependent Claim
42 words
Holographic scanner as defined in claim 5 wherein the holograms in said first set occupy a first sector of approximately 180° on the surface of said circular member while the holograms in said second set occupy a second sector of approximately 180°.
Claim 8
Dependent Claim
38 words
Holographic scanner as defined in any one of the preceding claims wherein said circular member is a transparent disk having said multi-segment annular track of holograms located at a predetermined radial distance from the center of the disk.
Claim 9
Dependent Claim
19 words
Holographic scanner as defined in claim 7 wherein the holograms are sandwiched between two bonded disks of transparent material.
Claim 10
Dependent Claim
111 words
Holographic scanner as defined in claim 7 or claim 8 wherein said optical system is composed of : a first set of mirrors, the longitudinal axes of which extend along planes parallel to the plane of the transparent disk, said first set of mirrors being adapted to redirect a deflected beam along paths extending approximately parallel to the plane of the transparent disk; and a second set of mirrors, the longitudinal axes of which extend along planes intersecting with the plane of the transparent disk, said second set of mirrors being adapted to redirect a deflected beam along paths approximately parallel to a normal from the surface of the transparent disk.
Claim 11
Dependent Claim
84 words
Label sensing system for reading bar code labels affixed to items being moved past a transparent window comprising : a holographic scanner as defined in any one of claims 1 to 9 in which said optical system redirects the deflected beam to form scan patterns extending over the area of said window; sensing means for detecting scattered radiation returned through the window after reflection from passing items, said sensing means being adapted to generate electrical signals proportional to the amplitude of the reflected radiation.
References Cited (Backward Citations)
No citation records indexed.
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