Browse Prior Art Database

Multi-Focal Plane Scanner With Dynamic Pattern Selection

IP.com Disclosure Number: IPCOM000046268D
Original Publication Date: 1983-Jun-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Broockman, EC: AUTHOR

Abstract

This article describes a supermarket scanner having two, alternately- energized lasers and a rotating disc with two annular sets of holographic optical elements (HOEs). Each set of HOEs generates a scan pattern consisting of a mixture of near and far focussed scan lines. The selection of the active laser is a function of a label candidate recognition process.

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Multi-Focal Plane Scanner With Dynamic Pattern Selection

This article describes a supermarket scanner having two, alternately- energized lasers and a rotating disc with two annular sets of holographic optical elements (HOEs). Each set of HOEs generates a scan pattern consisting of a mixture of near and far focussed scan lines. The selection of the active laser is a function of a label candidate recognition process.

Referring to the drawing, the scanner includes a rotating disc 10 with radially- spaced, annular tracks 12 and 14. Each of the tracks 12 and 14 consists of a series of holographic optical elements identified as 12A, 12B, ... and 14A, 14B,....
The output beam from a first laser 16 impinges on the facets of track 14, while the output beam from a second laser 18 impinges on the facets of track 12. As each individual facet moves through the impinging laser beam, the beam is deflected along a given scan line and is focussed at a given distance from the disc. Any given facet may have a focal length near the disc 10 or farther away from the disc 10. A "near" scan line is represented by arcuate arrow 20. A similar, "far" scan line is represented by arcuate arrow 22. The focal length of each scan line determines the region in which that scan line will most effectively "read" a UPC-type label on a grocery item 24.

Retroreflected light is focussed on a photodetector 26, the output of which is an electrical signal supplied to a candidate select and decode processor 28. The proc...