Browse Prior Art Database

Item Sensing in a Bar-Code Scanner Without Item-Sensing Rails

IP.com Disclosure Number: IPCOM000036265D
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Broockman, EC: AUTHOR [+3]

Abstract

This article describes a bar-code scanner design concept that allows the scanner to sense the presence of an item approaching the read zone of the scanner without requiring the item-sensing rails that are normally used for this purpose. The scanner can then turn on the scanning beam to read the bar code on the item and turn off the scanning beam after the code has been read. The concept combines the advantages of the use of item sensing (lower laser product classification, longer laser life, less customer annoyance) with the advantages of the rail- free, flatbed design (smooth scan surface, fewer parts, lower maintenance).

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Item Sensing in a Bar-Code Scanner Without Item-Sensing Rails

This article describes a bar-code scanner design concept that allows the scanner to sense the presence of an item approaching the read zone of the scanner without requiring the item-sensing rails that are normally used for this purpose. The scanner can then turn on the scanning beam to read the bar code on the item and turn off the scanning beam after the code has been read. The concept combines the advantages of the use of item sensing (lower laser product classification, longer laser life, less customer annoyance) with the advantages of the rail- free, flatbed design (smooth scan surface, fewer parts, lower maintenance).

The concept is based on the scanner operating in two modes - a search mode and a scan mode. In the search mode, the laser is turned on at low power for only a fraction of a revolution of the deflection device (rotating mirror or rotating holographic disk). During this mode, the scanner is "looking" for an item. Once an item is detected, the scanner switches into the scan mode. In this mode the laser is on all of the time at full power. This on-time is added into a timer/ accumulator circuit, which also monitors total clock time.

The timer/accumulator circuit allows the duty cycle of the laser beam (on-time divided by clock time) to be monitored. One can then limit the duty cycle so that the average laser power exiting the scanner (averaged over 1000 seconds) does not exceed the Class...