Browse Prior Art Database

Bistable Phosphor Plasma Display Device

IP.com Disclosure Number: IPCOM000075065D
Original Publication Date: 1971-Jul-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 3 page(s) / 36K

Publishing Venue

IBM

Related People

Kazan, B: AUTHOR

Abstract

This device enables the retaining of a luminescent pattern on a phosphor screen, utilizing secondary emission to produce bistable storage action. It is an improvement over known like devices in that, instead of requiring a flood gun and large evacuated envelope, it makes use of a gas plasma as a broad area source of electrons to thereby enable the obtaining of image storage in a flat structure.

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Bistable Phosphor Plasma Display Device

This device enables the retaining of a luminescent pattern on a phosphor screen, utilizing secondary emission to produce bistable storage action. It is an improvement over known like devices in that, instead of requiring a flood gun and large evacuated envelope, it makes use of a gas plasma as a broad area source of electrons to thereby enable the obtaining of image storage in a flat structure.

In the device shown, a discharge is maintained in a low-pressure gas such as 1 Torr of He within the envelope 2 by employing a voltage source 4 which is applied across the extended electrodes 6 and 8. Different from known plasma devices, a low-voltage mesh 10 is provided which is maintained at a voltage of about 5 volts by source 12. Mesh 10 is positioned close to but spaced from a phosphor screen 14 which is maintained at a relatively high voltage by a voltage source 16, source 16 suitably being about 100 volts. Because of the close spacing such as less than 1 mm between mesh 10 and phosphor screen 14, a discharge therebetween is prevented. By utilizing the secondary emission processes occurring at the phosphor surface, there can be employed an insulating phosphor of a type used in conventional cathode-ray tubes such as Zn SiO(2)(Willemite).

In accordance with prior practices, if phosphor layer 14 is porous, it remains stable either at a potential close to zero or at the potential of the transparent backing electrodes 18. Thus, if it is assumed that, initially, the surfaces of all of the phosphor elements are at zero potential, they remain at this potential by the impinging of the low-voltage electrons thereon, and no light is emitted therefrom. However, if a particular phosphor element is momentarily made more positive by applying a 20 volt pulse to terminal b, for example, this causes the secondar...