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Optically Controlled Latch Circuit

IP.com Disclosure Number: IPCOM000098348D
Original Publication Date: 1960-Aug-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Akmenkalns, IG: AUTHOR [+2]

Abstract

The circuitry is used to control an Esaki diode, transistor latch circuit. To transfer the latch between the two stable states, current has to be alternately added and subtracted from the transistor base node. This control current has to be provided for a short time, long enough only to transfer the circuit to its other stable state, after which the control current can be removed.

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Optically Controlled Latch Circuit

The circuitry is used to control an Esaki diode, transistor latch circuit. To transfer the latch between the two stable states, current has to be alternately added and subtracted from the transistor base node. This control current has to be provided for a short time, long enough only to transfer the circuit to its other stable state, after which the control current can be removed.

The light sensitive devices PC 1 and PC 2, when in the dark state, present a high resistance to the circuits consisting of resistors RG 1 and RG 2, voltage supplies -V2 and +V3 and the latch circuit. As light of sufficient intensity is applied to PC 1 and PC 2 the resistance of the respective circuit is reduced with a resulting change in the current provided by the control circuit to the latch. If light is applied to PC 1, current flows from the reference terminal towards voltage supply -V2 and the Esaki diode D 1 is switched to the highest voltage state. If light is applied next to PC 2, current flows from voltage supply+ V3 towards the reference terminal and the Esaki diode switches to its low voltage state. In this manner the latch circuit is transferred between the two stable operating points. Resistor RS provides the necessary bias current for bistable operation.

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