Browse Prior Art Database

Anti Crosstalk Code Reader

IP.com Disclosure Number: IPCOM000087552D
Original Publication Date: 1977-Feb-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Stanley, RC: AUTHOR

Abstract

This is an anti-crosstalk code reader for reading a serial number or other data on a photolithographic mask or any other item located inside a sealed container. The code consists of an arrangement of opaque and lank spaces on the item to be read and the reader consists of opposing arrays of light sources and photosensors that are physically placed in the same pattern as all possible bit locations on the item to be read.

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Anti Crosstalk Code Reader

This is an anti-crosstalk code reader for reading a serial number or other data on a photolithographic mask or any other item located inside a sealed container. The code consists of an arrangement of opaque and lank spaces on the item to be read and the reader consists of opposing arrays of light sources and photosensors that are physically placed in the same pattern as all possible bit locations on the item to be read.

Problems can arise when the item and container are large and the sensors must be placed at a distance from the light source and/or when the code marks are small and close together. The distance problem is eliminated in the present device by using high-power directional light emitting diodes (LEDs) as the light source and sensitive highly directional photosensors that are spectrally matched to the light source, (i.e., infrared).

The close proximity of code bits can create a problem of cross-talk (a sensor that is reading an opaque code mark being erroneously illuminate by light leaking or crossing over from adjacent clear code bits). This problem is minimized by pulsing the light emitters one at a time in sequence, and at the same time enabling the opposing light sensors one at a time in the same sequence. Consequently, the only requirements are being able to see through a clear bit space and not being able to see around an opaque bit space with only one light source on and one sensor enabled.

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