Patent GB-1351870-A (GB)
Title: Gas discharge panels and visual data conversion and storage systems
IPC: G09G3/28
Filed: 1971-04-19
Abstract: 1351870 Gas discharge display panels OWENS-ILLINOIS Inc 19 April 1971 [5 Feb 1970] 21067/71 Heading H1D A gas discharge panel comprises a sealed gas chamber 44, a pair of conductor arrays 26 or 28 arranged one on each of the opposite sides of the gas chamber, each array comprising a plurality of conductors and the conductor arrays being transversely orientated to each other so as to provide a plurality of cross-points between the conductors in the opposite arrays, dielectric means 32, 34 arranged between the conductor arrays and the gas chamber and providing surfaces defining at least a portion of the gas chamber, and photoemissive means 36, 38 arranged relative to the cross-points so as to be operative in response to illumination of a selected cross-point to facilitate a discharge within the gas chamber at the selected cross-point. The panel 10 comprises plates 22 and 24 of electrically inert material, e.g. soda lime glass carrying the conductor arrays 26 and 28 in the form of wires or filaments or coatings formed by photoetching, vacuum deposition, or stencil screening. Suitable electrode materials are Cu, Au, Ag, Al and tin oxide. The dielectric members 32 and 34 may be of lead-dioxide, silicon dioxide, boron oxide and/or strontium oxide type glass, which is screened on the plates 22 and 24 in the form of a frit and then cured. The photo-emissive coatings 36 and 38 may be a metal, e.g. Cs, Ba, Rb, or Na; a combination of metals, e.g. Cs and Sb, Rb and Sb, Cs and Au, or Cs and Bi; a combination of metals and a semiconductor, e.g. caesiated gallium arsenide, caesiated gallium phosphide, or caesiated silicon; a semi-conductor alone, e.g. caesium oxide, gallium phosphide, silicon, or a compound of gallium, arsenic and phosphorus; or a combination of semiconductors, e.g. caesium oxide and compounds of Ga, In and As. The photoemissive material may be provided on only one of the dielectric members 32 and 34. Alternatively, photoemissive material, e.g. Cs 2 O, may be included in the material of one or both of the members 32 and 34, or those members may be rendered photoemissive by irradiation. The plaste assemblies are separated by spacers 40 to provide the required gap size, e.g. 4 to 9 mils. and are sealed together by devitrified glass 42 to form an enclosure which is filled with Ne plus a small amount of A, Kr or Xe to provide a Penning mixture, or with 90% Ne + 10% N. The conductor arrays 26 and 28 are connected to a power source 46. The panel may be included in a visual data conversion and storage system (Fig. 1, not shown) comprising an image projector and a read-out device such as a camera or an array of light detectors such as photodiodes or photoconductors controlling a printer or some kind of memory. Alternatively a read-out circuit 54 may be connected to the conductor arrays 26 and 28. In an alternative form of panel (Fig. 3, not shown) the photoemissive elements 36 and 38 are non-continuous and may be variously shaped and disposed (Figs. 4 to 6, not shown). A further alternative form of panel (Fig. 8, not shown) includes an apertured light absorber to prevent illumination at one cross-point from affecting adjacent cross-points.