Method Of Spacing The Plates Of A Gaseous Discharge Device

Abstract

A pair of glass plates of a gaseous discharge display or memory device are held precisely spaced by two sets of identically sized overlapping spacer rods. The rods crisscross orthogonally within a sealed gas-containing chamber to create gaps through which the gas can flow without significant restriction between areas of the chamber separated by said rods. Sealing rods of glass having a softening temperature lower than that of the spacer rods are disposed like a border around the spacer rods and are of significantly greater diameter or height than the combined height of the two superposed sets of spacer rods. Initially the upper plate is supported solely by sealing rods; but upon heating of the assemblage, the sealing rod glass reflows, and the upper plate settles until it contacts the upper set of spacer rods; whereupon the assembly is cooled and the sealing rods fuse with the plates to create an impermeable chamber between the now precisely spaced plates.

Parent Case Text

This application is a division of application Ser. No. 251,483 now U.S. Pat. No. 3,808,497 filed May 8, 1972 entitled, Gaseous Discharge Device and Method of Spacing The Plates Thereof, assigned to the assignee of the present invention.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

U.S. Pat. application of R. Langston et al., Ser. No. 214,298, filed Dec. 30, 1971, now U.S. Pat. No. 3,778,127, entitled "Sealing Technique for Gas Panel," assigned to the assignee of the present invention.

BACKGROUND OF THE INVENTION

This invention relates to gas discharge display and/or memory devices, and more particularly to improved devices of this type embodying a method of spacing the plates with spacer elements that do not inhibit flow of gas particles between areas separated by such spacer elements.

In the above-referenced copending application of R. Langston et al., there is disclosed a gaseous discharge display device in which the superposed glass plates are accurately spaced apart using a combination of low-softening-point sealing rods and high-softening-point spacer rods. The large diameter sealing rods are orthogonally arranged in a window frame-like border around the significantly smaller diameter orthogonally arranged single layer of spacer rods. When the plates and rods are heated, the glass of the sealing rods reflows, causing the upper glass plate to settle gradually into contact with the high-softening-point spacer rods for accurately spacing the upper plate relative to the lower plate. When the assembly is cooled, the sealing rods fuse to the plates, creating a chamber of precise constant height into which an illuminable gas is later introduced and sealed.

This device and method are very satisfactory where the area of the plates is relatively small and the spacer rods need only frame the display area. However, as the plate area and hence the display area are increased, spacer rods must be introduced at other intermediate locations within the chamber to maintain the critical precise spacing between the plates. In such case, the spacer rods can extend only a short distance in either direction because wherever they are present (except at the edges of the display area) they present a barrier. This barrier impedes the flow of gas particles, metastable ions, photons, etc., between adjacent areas separated by the spacer rods; and it can also inhibit conditioning of cells, especially those immediately adjacent the spacer rods.

There is a need for a spacing arrangement that will provide accurate spacing of glass plates in gaseous discharge devices having large display areas requiring spacers at various places within the display area as well as around the periphery thereof. It would also be desirable to minimize the size of the spacer elements for aesthetic reasons so they will not be visible and mar the display area, and at the same time provide greater latitude in their location.

SUMMARY OF THE INVENTION

Toward this end, and according to the invention, applicants have found that these objectives can be achieved by an improved gaseous discharge display and/or memory device and method which, insofar as is known, have never heretofore been proposed. In this device and according to applicants' improved spacing method, the plates are held precisely spaced at a preselected constant distance by two sets of identically sized crisscrossing spacer rods disposed orthogonally with respect to each other in overlapping lattice-like contact within the sealed gas-containing chamber. The spacer rods of one set contact the dielectric coating over the parallel conductors on one of the plates; and the spacer rods of the other set contact the dielectric coating over the orthogonally arranged parallel conductors on the other plate. Since these spacer rods have diameters equal to only one-half of said preselectd constant distance, flow of gas particles between areas separated by the spacer rods is not significantly impeded. The spacer rods associated with the conductors on each plate are disposed between, and extend parallel to, the conductors on that particular plate. The diameters of the spacer rods preferably vary between approximately 0.002 inch and 0.0037 inch, according to which of the embodiments, hereinafter described, is employed.

Other objects and advantages will become apparent from the following more detailed description of the invention and from the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view, partly broken away, of a gaseous discharge display device embodying the invention;

FIG. 2 is a fragmentary sectional view, to substantially enlarged scale, taken along the line 2-2 of FIG. 1, showing a preferred embodiment of the invention;

FIG. 3 is a sectional view, to somewhat exaggerated scale, showing the assemblage before a heat fusion step that results in the configuration shown in FIG. 2; and

FIG. 4 is a fragmentary sectional view, similar to FIG. 2, but showing an alternate embodiment of the invention.

DESCRIPTION OF PREFERRED EMBODIMENT

The gaseous discharge display and/or memory device constructed according to this embodiment and illustrated in FIGS. 1-3 comprises, briefly, an upper glass plate 10 and a lower glass plate 11, each including substrates 12,13, respectively, on the facing surfaces of which are formed passivated metalized conductor arrays 14,15, respectively. As illustrated, the arrays 14,15 each comprise respective pluralities of parallel conductors, the conductors of array 14 being disposed orthogonally relative to those of array 15. The ends of the array on each plate extend beyond the edges of the other plate to facilitate connection to alternate conductors of the array, in conventional manner. As best shown in FIGS. 2,3, the conductors of each array 14,15 are overlaid with respective transparent dielectric coatings 16,17, preferably of glass, which provide flat surfaces 18,19, respectively.

The plates 10,11 are fused into an integrated structure in the following manner. Unfused, heat-fusible sealing material, preferably in the form of rods 20 of low-softening-point glass, are placed in a window-frame border-like pattern on surface 19 of lower plate 11. These rods 20 are of an identical diameter that is significantly greater than the precise preselected distance at which these plates are ultimately to be joined. According to the invention, two sets of identically sized upper and lower spacer rods 21,22 are then placed in overlaying relation in a two-stratum crisscross pattern within the border. The lower rods 22 extend parallel to, and are equidistantly spaced between, adjacent pairs of conductors in array 15 and rest on flat surface 19; whereas upper rods 21 overlay and rest on lower rods 22 in a predetermined lateral spacing hereinafter to be described. As will be noted from FIG. 3, the combined height of the overlapped rods 21,22 is substantially less than the diameter of the sealing rods 20.

The upper plate 10 is now positioned over the lower plate 11 with upper plate surface 18 contacting sealing rods 20 and transversely positioned such that the upper spacer rods 21 extend parallel to, and equidistant from, but substantially below, pairs of adjacent conductors of array 14 (as a result of the aforesaid predetermined spacing of rods 21 on rods 22). Rods 21,22, which are preferably formed of glass, have a significantly higher softening point than that of the sealing rods. Hence, when the unfused assemblage of discrete parts is thereafter heated in a vacuum oven to a temperature sufficient to cause melting and reflow of the sealing material of rods 20, upper plate 10 will gradually settle from the position shown in FIG. 3 until surface 18 contacts upper spacer rods 21, as shown in FIG. 2.

The assemblage is now permitted to cool, causing the now reflowed sealing material, designated 20' in FIG. 2, to fuse to the surfaces 18,19 of the respective dielectric layers 16,17 and thereby fuse plates 11 into an integrated structure having an impermeable chamber 23 sealed about its periphery by the material 20'. In accordance with conventional practice, this chamber 23 is now evacuated via an exhaust tube 24 (FIG. 1), then charged with an illuminable gas at appropriate pressure; whereupon the tube is sealed to permanently entrap the gas within the chamber.

It will thus be seen that according to a feature of the invention, the plates will be maintained at a precise preselected distance by the crisscross pattern of overlapping spacer rods 21,22. Because these spacer rods have a diameter which is equal to only one-half of the total constant space between the surfaces 18,19, the gas particles, metastable ions, protons, etc., may flow without significant restriction between the various areas into which the chamber 23 is separated by the lattice arrangement of spacer rods.

In the preferred embodiment illustrated in FIG. 2, the sealing rods 20 preferably have a diameter of about 0.040 inch, and the spacer rods 21,22 preferably have a diameter of approximately 0.002 inch; and dielectric coatings 16,17 have a softening temperature which is above the temperature to which the assemblage is subjected during the above-described fusing operation so that the rods 21,22 will contact, but not penetrate, the dielectric surfaces 18,19. With this arrangement, the small size of the spacer rods renders them substantially indistinguishable from the glass plates and hence is aesthetically desirable. Also, blocking of the display area at the crossover points of the respective rods 21,22 is minimized by spacing these rods between conductors so as not to blank out any appreciable illumination upon firing of cells comprised of conductors adjacent to these rods.

DESCRIPTION OF ALTERNATE EMBODIMENT

The device and sealing method employed according to this embodiment (see FIG. 4) are identical with those already described in connection with the embodiment of FIGS. 1-3, except in the following respects: According to the instant embodiment, the upper and lower spacing rods 21',22' , respectively, are of somewhat larger diameter, such as 0.0037 inch; and the coatings 16',17' are of a dielectric having a softening temperature which is below the temperature to which the assemblage is heated during the fusing process. As a result, the spacer rods 21',22' will penetrate the dielectric coatings until they contact the surfaces of the respective substrates 12,13. Thus the constant spacing between the plates will be defined by respective contacts of the spacer rods 21',22' with the substrates rather than with the dielectric coatings; however, the actual constant height of the chamber 23 will still be that corresponding to the precisely fixed spacing between the flat portions of surfaces 18',19' .

It is to be understood that the conductor configuration and composition, the specific oven structure and temperatures used for the fusing operation, and the apparatus by which the chamber 23 is evacuated and then charged with illuminable gas may be as taught in the prior art, such as the above-referenced Langston et al. application; and hence they have not been described here in any more detail than is necessary for an understanding of the present invention.

While the invention has been shown and described with reference to preferred embodiments thereof, it will be understood that various substitutions and changes in form and detail may be made by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, the gas discharge display and/or memory device herein disclosed and the method of making same are to be considered merely as illustrative, and the scope of the invention is to be limited only as specified in the claims.

Claims

What is claimed is:

1. A method of sealing flat surfaces of two members in overlying relation at a precise preselected distance to create an impermeable chamber of constant height divided into areas by spacer elements that do not significantly impede flow of gas between such areas in the chamber, comprising the steps of

providing two substantially transparent flat members, each said member having parallel conductors overcoated with a thin layer of dielectric material,

placing on one of the members a border of unfused heat-fusible material having a height significantly greater than said constant height,

placing spacer elements of substantially identical thickness in a two-stratum crisscross pattern within said border to a combined height significantly less than the minimum height of said material,

placing the other member with its flat surface supported on said heat-fusible material, and

heating such assemblage to a temperature above the softening point of said sealing material but below the softening point of the spacer elements to effect fusion of said material and members to create said chamber as, and in consequence of, said other member settling during such heating and fusing until it is supported at said constant height by said crisscrossed arrangement of spacer elements.

2. A method of making a gaseous discharge display device, comprising the steps of

providing two substantially transparent flat members, each with conductor arrays overcoated with a dielectric material,

placing unfused heat-fusible sealing material over the dielectric material on one of the members as a frame-like border enclosing the major portion of its conductor array, said border having a height substantially greater than the final constant spacing desired between said members,

disposing two sets of spacer elements of identical height between the members to create an assemblage in which the elements orthogonally overlap in a lattice-like relation within the bordered area, elements of one set resting on said one member and supporting overlying elements of the other set, the combined thickness of both sets of elements being substantially less than the height of said border so that said other member is initially supported by the sealing material, and

heating the assemblage to a temperature above the softening point of said sealing material but below the softening point of the spacer elements to effect fusion of said sealing material and members to create an impermeable chamber for confining a predetermined volume of gas, said other member settling during such heating and fusing until it is supported at said final constant spacing by said lattice arrangement of overlapping elements to permit the gas to flow without significant restriction to substantially all areas of said sealed member separated by said spacer elements.

3. The method according to claim 2, wherein

the conductors of each member are disposed orthogonally to the conductors of the other member, and

spacer elements of said one set are disposed equidistant between, and extend parallel to, pairs of adjacent conductors on the said one member, and

spacer elements of said other set are disposed equidistant between, and extend parallel to, pairs of adjacent conductors on said other member.

4. A method of making a gaseous discharge display device, comprising the steps of

providing two transparent flat members, each with conductor arrays formed on a substrate and overcoated with a layer of a dielectric material,

placing unfused heat-fusible sealing material over the dielectric material on one of the members as a frame-like border enclosing the major portion of its conductor array, said border having a height substantially greater than the final constant spacing desired between said members,

disposing two sets of spacer elements of identical height between the members to create an assemblage in which the elements orthogonally overlap in a lattice-like relation within the bordered area, elements of one set resting on the layer of said one member and supporting overlying elements of the other set, the combined thickness of both sets of elements being substantially less than the height of said border so that said other member is initially supported by the sealing material, and

heating the assemblage to a temperature above the softening point of said sealing material and dielectric material but below the softening point of the spacer elements to effect fusion of said sealing material and members to create an impermeable chamber for confining a predetermined volume of gas, said other member and both spacer elements settling during such heating and fusing until said other member is supported at said final constant spacing by said lattice arrangement of overlapping spacer elements to permit the gas to flow without significant restriction to substantially all areas of said sealed members separated by said spacer elements, said spacer elements penetrating said layers of dielectric material substantially into contact with the substrates.