Browse Prior Art Database

Optical Reader Device

IP.com Disclosure Number: IPCOM000094009D
Original Publication Date: 1966-Apr-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Prot, J: AUTHOR [+2]

Abstract

The circuitry provides for gain control in an optical reader for punched tape. Paper tape is highly transparent. In its use, spurious movement is not encountered. MYLAR* tape has better opacity, but spurious movement is encountered. This device uses the MYLAR opacity to compensate for spurious movement. *Trademark of E. I. du Pont de Nemours and Co.

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Optical Reader Device

The circuitry provides for gain control in an optical reader for punched tape. Paper tape is highly transparent. In its use, spurious movement is not encountered. MYLAR* tape has better opacity, but spurious movement is encountered. This device uses the MYLAR opacity to compensate for spurious movement. *Trademark of E. I. du Pont de Nemours and Co.

A threshold reader is used. Its input stage load lines are changed as soon as punched hole start is sensed. The retriggering threshold is reached only after there occurs an appreciable light variation substantially more than that variation necessary at the system's initial state. Drawing 1 shows the circuit diagram and drawing 2 the input stage static characteristics.

The device includes phototransistor Pt, amplifier 1, and Schmidtt trigger St, transistors 2 and 3, whose state is transferred via transistor 4. The load line switch in portion Gc comprises transistors 5 and 6, line 7, and command line MYLAR Mode. When Gc is placed in an operative state, via excitation of MYLAR Mode, a punched hole reading first goes through an opaque area, then through a light area and finally back to an opaque area.

Light intensity first increases from a low value up to L. Voltage at points V and X decreases. The operating point follows load line D1 in drawing 2 down to value V1. Here the voltage at X is low enough to cut off transistor 2 and transistor 3 conducts. The voltage at M is such that transistor 5 conduct...