Browse Prior Art Database

Velocity Calibrating Scanner

IP.com Disclosure Number: IPCOM000078094D
Original Publication Date: 1972-Nov-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 58K

Publishing Venue

IBM

Related People

Davis, JB: AUTHOR [+3]

Abstract

A system is described which provides a signal proportional to the velocity variations of a hand-held scanner, as it is passed over the black and white indicia of a bar code. The system is also compatible with the Delta C type decoding which minimizes threshold difficulty. Delta C decoding relates to time measurements of threshold crossings in the same sense (black, white to black, white, etc.) as opposed to Delta B type decoding, which is based on time measurements between adjacent threshold crossings (black, white to white, black to black, white, etc.)

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Velocity Calibrating Scanner

A system is described which provides a signal proportional to the velocity variations of a hand-held scanner, as it is passed over the black and white indicia of a bar code. The system is also compatible with the Delta C type decoding which minimizes threshold difficulty. Delta C decoding relates to time measurements of threshold crossings in the same sense (black, white to black, white, etc.) as opposed to Delta B type decoding, which is based on time measurements between adjacent threshold crossings (black, white to white, black to black, white, etc.)

The system includes the scanner and the recognition electronics. The scanner, as shown in Fig. 1, consists of a support block containing light sources 2 and 3 to illuminate the record and a single trapezoidal aperture to receive light reflected from the record. Two photosensors 4 and 5 are located above the aperture on top of the block. The two photosensors are separated by a fixed distance, such that as the scanner moves over the record the sensors will produce similar signals slightly displaced in time, and the sensing of an arbitrarily assigned threshold level will also be displaced in time. Assigning the passing of the threshold toward black as a logical "1" and the passing toward white as a logical "0", an exclusive OR 6, as shown in Fig. 2, between the sensors will produce a signal proportional in width to the velocity of the scanning head.

The output from the exclusive OR is com...