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Electronic Readout Tunnel Diode Memory

IP.com Disclosure Number: IPCOM000094893D
Original Publication Date: 1965-Jun-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Lynch, RJ: AUTHOR [+2]

Abstract

By an extension of the principles of operation of the Scanistor (see this number, page 196), and the use of the bistable nature of the tunnel diode, a memory can be created as shown. The memory offers the capability of detecting and storing a pattern of light and dark areas such as that generated by interposing a punched card between a light source and the memory array.

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Electronic Readout Tunnel Diode Memory

By an extension of the principles of operation of the Scanistor (see this number, page 196), and the use of the bistable nature of the tunnel diode, a memory can be created as shown. The memory offers the capability of detecting and storing a pattern of light and dark areas such as that generated by interposing a punched card between a light source and the memory array.

Initially with all tunnel diodes reset to the 0 state, shown by 0 on the V-I diagram, light incident on any one or more of the photodiodes causes the corresponding tunnel diode to switch. Such is to that point on the V-I curve in which the conduction is at the high level A. When the light is extinguished, the switched tunnel diodes remain switched but conduct with the normal bias current shown at B. To read out the state of the memory array, a positive-going ramp voltage is applied to the terminal 10. Each previously switched tunnel diode switches back to the 0 state in succession. Such action is accompanied by a corresponding succession of output pulses at 11 as each tunnel diode undergoes the transition from point X to point Y on the curve.

To reset the memory without readout, the bias voltage is reduced to zero. The successive interrogation of the state of each of the tunnel diodes occurs as the ramp voltage applied to terminal 10 reduces the current flow through the serially connected diodes. This causes each tunnel diode to undergo the transition from X...