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Light Coupled Threshold Logic

IP.com Disclosure Number: IPCOM000096710D
Original Publication Date: 1963-Sep-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Dumke, WP: AUTHOR

Abstract

The fabrication and characteristics of a light sensitive bistable element, such as a diode with light output, make possible threshold logic. Such is based on the critical intensity of light necessary to switch the element into its high current state. When such a device is biased close to its voltage maximum as in the curve, a given amount of light intensity can switch it into its high current state 12. The bias and light signal intensity are so adjusted that a certain minimum number of simultaneous sources of light are necessary to trigger the diode into its high current state in which it will have considerable light output itself.

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Light Coupled Threshold Logic

The fabrication and characteristics of a light sensitive bistable element, such as a diode with light output, make possible threshold logic. Such is based on the critical intensity of light necessary to switch the element into its high current state. When such a device is biased close to its voltage maximum as in the curve, a given amount of light intensity can switch it into its high current state 12. The bias and light signal intensity are so adjusted that a certain minimum number of simultaneous sources of light are necessary to trigger the diode into its high current state in which it will have considerable light output itself.

An example of such circuitry is a binary to octal converter, shown above. The bias is set so that only the diode which receives three simultaneous light pulses is triggered into its high current light emitting state. Variations are also possible. For example, the output can be electrical.

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