Browse Prior Art Database

Wire In Cable Identification Device using Liquid Crystals

IP.com Disclosure Number: IPCOM000079981D
Original Publication Date: 1973-Oct-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 23K

Publishing Venue

IBM

Related People

Abbatecola, R: AUTHOR [+3]

Abstract

Wire identification instruments are now widely used to reduce time in construction of multiconductor cables with connectors. Normally, such instruments allow arbitrary selection of a wire by a worker with his fingertips and automatic identification of the wire by a display. Such instruments require the worker to wear a high-impedance wristband to complete a circuit.

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Wire In Cable Identification Device using Liquid Crystals

Wire identification instruments are now widely used to reduce time in construction of multiconductor cables with connectors. Normally, such instruments allow arbitrary selection of a wire by a worker with his fingertips and automatic identification of the wire by a display. Such instruments require the worker to wear a high-impedance wristband to complete a circuit.

A low-cost instrument is suggested which eliminates need for the high- impedance wristband. More specifically, the use of a high-impedance liquid display device is suggested to provide both the cable sensing and display function, in combination with a low-voltage excitation signal and the use of the worker's body capacitance-to-ground to complete the circuit.

An equivalent circuit of such a test system is illustrated wherein: C1 is the capacitance of a selected cell of a liquid crystal display device; C2 is the cell capacitance of an insulated cell; C3 is the body-to-ground capacitance of the worker; C4 is the capacitance between a selected wire and a jth wire; and V is the AC input from the secondary voltage of a transformer.

For very long, parallel, tightly wrapped cables, a wire-to-wire capacitance might be so large that most of the voltage appearing across a selected cell might also appear across an unselected cell. This consideration would then indicate the desirability of utilizing a liquid crystal system which has a sharp voltage thresho...