Browse Prior Art Database

Waveform Analyzing Test Process

IP.com Disclosure Number: IPCOM000087417D
Original Publication Date: 1977-Jan-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 3 page(s) / 42K

Publishing Venue

IBM

Related People

Miner, LE: AUTHOR [+2]

Abstract

An optical reading device for reading bar code labels, such as those used with the universal product code (UPC), may be tested using recordings mounted in static positions with respect to the device read window. The static positions are selected to simulate all stress conditions and utilize the positions of maximum stress.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 3

Waveform Analyzing Test Process

An optical reading device for reading bar code labels, such as those used with the universal product code (UPC), may be tested using recordings mounted in static positions with respect to the device read window. The static positions are selected to simulate all stress conditions and utilize the positions of maximum stress.

The figure illustrates a read window 4, and the closed curved line 5 shows the Lissajous pattern path scanned by the laser beam. The rectangles 6 are the static test positions at which the bar code labels are positioned to simulate conditions of maximum stress. As the laser beam is passed over a label the reflected light is sensed by a photomultiplier tube (PMT). The black and white bars on the label will be reproduced as an analog signal from the PMT. The analog signal is converted to digital information which is sent to be decoded in the controller.

The wavefonm test method uses the static bar code positions relative to the read window and counts the number of recordings. These recordings are analyzed by measurement of the pulse widths. By software, ratios are derived from the widths in much the same manner as the recognition logic. Through a comparison of these ratios to an upper and lower limit, the individual recording can be determined to be in or out of the specifications. The specific test of the UPC generates eleven ratios for each recording and each ratio must be in the specifications for the recording to be in the specifications. The number of recordings in the specifications compared with the total number of recordings determines the consistency of the scanner and the consistency typifies the scanner performan...