Browse Prior Art Database

Photosensitive Facsimile Device

IP.com Disclosure Number: IPCOM000087682D
Original Publication Date: 1977-Mar-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 24K

Publishing Venue

IBM

Related People

DePalma, C: AUTHOR [+4]

Abstract

Top electrode 1 is transparent and electrically conductive. Dielectric 2 is transparent. Photoconductor 4 has no free carriers at room temperature in darkness. Bottom electrode 5 is conductive.

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Photosensitive Facsimile Device

Top electrode 1 is transparent and electrically conductive. Dielectric 2 is transparent. Photoconductor 4 has no free carriers at room temperature in darkness. Bottom electrode 5 is conductive.

To store optical data, e.g., an image, voltage source 8 is connected to electrodes 1 and 5. Light 7, shining onto surface 6, frees carriers in photoconductor 4. The capacitor with dielectric 2 is charged and remains charged upon removal of light 7 and voltage source 8.

Then, electrodes 1 and 5 are connected by short circuit 9. This charges the capacitor with photoconductor 4. The holes at the interface 3 are trapped by surface states or by hole traps that were placed during the manufacture of the device.

Now, an image is focused onto surface 6. In light receiving areas, carriers will be generated in photoconductor 4 and move with the field, thus partly cancelling the charge on electrodes 1 and 5, and interface 3.

Readout is done by scanning a light beam across surface 6 and connecting amplifier 10 to electrodes 1 and 5. Scanning the light beam frees the carrier in photoconductor 4. In areas that have been exposed during imaging, freed carriers will recombine and no current is sensed by amplifier 10. When the light beam scans unexposed areas containing trapped charges, the freed carriers will move with the field present and a current is sensed by amplifier 10.

In a second method, the voltage source 8 is connected to electrodes 1 and 5, and su...