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Encoding and Detecting Arrangement

IP.com Disclosure Number: IPCOM000092020D
Original Publication Date: 1968-Aug-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Chang, DC: AUTHOR

Abstract

In an optically accessed memory of the holographic type, the reconstructed image from a block of memory is detected by an array of photodetectors. Detection of the stored information is accomplished in readout by encoding each information bit in two half-cells of the memory arrangement. In the memory, light and dark spots represent the bits of information. One half-cell is always light, the other dark. The information bits are defined as a 1 bit when the light is in one half-cell and as a 0 bit when the light is in the other half-cell.

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Encoding and Detecting Arrangement

In an optically accessed memory of the holographic type, the reconstructed image from a block of memory is detected by an array of photodetectors. Detection of the stored information is accomplished in readout by encoding each information bit in two half-cells of the memory arrangement. In the memory, light and dark spots represent the bits of information. One half-cell is always light, the other dark. The information bits are defined as a 1 bit when the light is in one half-cell and as a 0 bit when the light is in the other half-cell.

In the detection system, each bit detector also includes two half-cell 1 and 2. Corresponding half-cells in the matrix arrangement are connected to sense line cells 3, 4 and 3a, 4a which are connected in turn to differential amplifiers 5 and 5a. Word lines 6 and 6a for the matrix are connected to both half-cells of a bit detector.

A gating cell includes light diodes 7 and 8 positioned to accept light projected from a corresponding bit position of the memory. Diodes 9 and 10 are blocking elements. Gate terminal 11 of the cell is connected to a word line and is normally biased slightly positive. Diodes 7 and 9 are connected serially and in parallel with the serial arrangement of diodes 8 and 10. Diodes 7 and 8 are connected to the sense line pair.

During readout, a small negative pulse is applied at gate 11, forward biasing diodes 9 and 10 to unblock any photogenerated current in diodes 7 and 9. If...