Browse Prior Art Database

Holographic Disk Design for Reduced Bar Code Scanner Height

IP.com Disclosure Number: IPCOM000037831D
Original Publication Date: 1989-Jul-01
Included in the Prior Art Database: 2005-Jan-30
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Fortenberry, RS: AUTHOR

Abstract

The disclosed holographic disk design allows for reduction in the height of a bar code scanner optical cavity without a reduction in function.

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Holographic Disk Design for Reduced Bar Code Scanner Height

The disclosed holographic disk design allows for reduction in the height of a bar code scanner optical cavity without a reduction in function.

Supermarket bar code scanners require omni-directional "Bar-X" scan patterns so that bar codes passing over the scanner window in random orientations can be read. The omni-directional pattern is created when individual holographic facets direct the scanning beam into a post-disk mirror array. Several sets of mirrors exist in the array, with each set creating scan lines that exit the scanner window with a different orientation.

The volume required for the mirror array limits efforts to reduce the volume of the overall scanner package. To avoid mechanical interferences between sets of mirrors, a certain volume directly above the disk must be kept free of mirrors.

With existing holographic disks, the light collection area of each holographic facet is distributed in an annular sector that extends from the inner radius to the outer radius of the disk. The disclosed holographic disk designs use inner and outer collection zones, with some facets collecting from the outer zone and other facets collecting from the inner zone.

The figure shows an existing holographic disk and the disclosed holographic disk. With the light collection function distributed into inner and outer zones, post-disk mirrors can be placed closer to the disk without creating interferences between mirr...