Browse Prior Art Database

Linear Scan Bar Code Reader System

IP.com Disclosure Number: IPCOM000099912D
Original Publication Date: 1990-Feb-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 4 page(s) / 123K

Publishing Venue

IBM

Related People

Chu, KL: AUTHOR [+4]

Abstract

A system to read the bar code on a product is described. This system provides a constant velocity linear motion to scan the bar code, an analog front end to process the bar code signals, and a microprocessor to interpret the product identification (ID) from the bar code signals.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Linear Scan Bar Code Reader System

       A system to read the bar code on a product is described.
This system provides a constant velocity linear motion to scan the
bar code, an analog front end to process the bar code signals, and a
microprocessor to interpret the product identification (ID) from the
bar code signals.

      Fig. 1 illustrates an exemplary bar code system designed to
read the bar code inscribed on silicon wafers. Shown in Fig. 1 are:
wafer 1, which is the product containing the bar code; linear scan
subassembly 2; and control unit subassembly 3.

      Linear scan subassembly 2 consists of bar code sensor 4, power
decouplers 5, threshold potentiometer 6, preamplifier 7, threshold
generator 8, pulse shaper 9, left and right sensors 10, power
decouplers 11, motor 12, linear scan unit 13 and analog front end
circuit card 14.

      The bar code sensor 4 is packaged on analog front end card 14
and rides on a slide located within linear scan unit 13 driven back
and forth between right and left position sensors 10 by means of
motor 12.

      Control unit subassembly 3 consists of microprocessor 15, RS232
communications interface 16, RS232 cable 17, power terminals 18,
power decouplers 19, scan control logic 20, motor driver 21, motor
power supply 22, dip switches 23, clock circuity 24, analog front end
power supply 25, linear scan cable 26 and right and left sensor
control cables 27.

      Microprocessor 15 is designed to communicate with a host
computer through RS232 interface 16 and cable 17 and contains a 2K
internal program storage in the form of an EPROM which can be erased
and reprogrammed if any changes are required in the bar code
interpreting algorithm.  The code in the EPROM is used to interpret
product ID characters from the bar code signals due to the code
structure.

      In actual operation, product wafer 1, is orientated so that the
bar code is aligned over bar code sensor 4.  The host computer
solicits product ID information after orientation is completed
through RS232 interface 16 and cable 17.  When microprocessor 15
receives the command to read ID, it generates the necessary scan
motion, interprets the code, checks for validity and then sends the
ID to the host computer.

      The optical sensing of the bar code is performed through analog
front end circui...