CA1060938A

CA1060938A - Gas panel spacer technology

Info

Publication number: CA1060938A
Application number: CA269,175A
Authority: CA
Inventors: Neil M. Poley; Marvin B. Skolnik
Original assignee: International Business Machines Corp
Current assignee: International Business Machines Corp
Priority date: 1976-01-08
Filing date: 1977-01-05
Publication date: 1979-08-21
Also published as: DE2655498A1; FR2337913B1; US4091305A; IT1070035B; JPS52100972A; DE2655498C2; JPS566622B2; FR2337913A1; GB1509487A

Abstract

ABSTRACT
IMPROVED GAS PANEL SPACER TECHNOLOGY
A gaseous discharge display and/or memory device comprises a pair of sealed glass plates having metallic conductor arrays formed thereon and insulated from contact with the gas by a dielectric layer. The crossover points of the conductors, which define the locations of the individual cells which cells are controlled by selective application of write, sustain, and erase signals. To permit uniform operation of individual cells, the plates must be maintained precisely spaced over their entire display surface. To effect this requirement in a large size panel, metallic spacers are secured to the upper surface of the conductors of the metallic conductor arrays prior to the forma-tion of the dielectric layer, the size and number of these spacers being determined by the geometry and resolution of the gaseous discharge display device.

Description

16 Cross Reference to Related Applications 17 ~.S. Application Serial No. 886,100 (IBM Docket Ki968018) ~ 18 "Gas Cell Type Memory Panel with Grid Network for E1ectrostatic 19 Isolation" filed by Frank M. Lay, December 18, 1969, now U.S.
Patent 3,666,981.
21 U.S. Application Serial No. 405,205 (IBM Docket Ki971015X) 22 "Gas Panel Fabrication" filed by Peter H. Haberland et al 23 October 10, 1973, now U.S. Patent 3,837,724.
~;~ 24 U.S. Application Serial No. 214,298 (IBM Docket Ki971004) "Sealing Technique for Gas Panel" filed by Perry R. Langston, Jr.
,. 26 et al, December 30, 1971, now U.S. Patent 3,778,127.
; 27 Background of the Invention . 28 This invention relates to gaseous discharge display and/or .: 29 memory devices and more partlcularly to large size high resolution devices of this type embodying a method of spacing Ki974023 ., ;i ,_ _. ... . _.. __ .; .

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1 the plates with spacer elements that do not inhibit flow of gas

2 particles within tlle panel, which are substantially invisible

3 and which can be interspersed across the display surface at pre-

4 determined or random intervals in accordance with the size of .

5 the panel and the specific geometric design of the conductor ~i 6 arrays.
;~ 7 Various methods have been employed in the prior art for 8 maintaining a uniform space or gap between opposing walls of a g gas discharge device, primarily involving the use of glass spacers generally in rod form, and various methods of gas panel 11 assembly using such spacers have been proposed. In one arrange-12 ment, disclosed in U.S. Patent 3,808,497 to Greeson, Jr. et al 13 hard glass spacer rods and soft glass sealing rods are spaced 14 about the periphery of a panel during the sealing cycle whereby the space between the plate is controlled by the peripheral 16 glass spacer rods when the glass sealant reflows. In other 17 arrangements for utilizing glass rods in a gas panel fabrication, 18 grooves can be cut in the panel subassembly by scoring the 19 dielectric after reflow to position and retain the glass spacer h 20 rods in position during the fabrication of the panel. However, 21 it is essential that the rods maintain their position during 22 assembly with utmost precision so as to avoid intrusion into 'A'.. 23 the operative portions of the display area. This presents a 24 difficult problem in fabrication since the rods are of such ,; 25 dimensions as to make handling extremely difficult and further 26 tend to move readily even from their grooved position during 27 the fabrication process so that additional care must be A 28 exercised in the fabrication to prevent lateral movement of the 29 rods.
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While this method has been employed successfully albeit Ki974023 .:"~, : .
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1 with the problems enumerated above, the method of framing the ,','!, 2 display area with rod glass spacers is limited to panels where ':.~t' 3 the plates are relatively small. As the display area and hence 4 the plate size are increased, spacer means must be introduced at intermediate locations within the chamber to maintain the

6 critical precise spacing between the plates. In methods

7 employed for medial spacing in the prior art, glass spacer rods

8 are positioned between adjacent rows or columns of cells rather

9 than obstruct the display area, thus tending to limit the resolution of the panel. Additionally, glass spacer elements 11 having medial locations in the panel tend to be visible and are 12 considered undesirable from an aesthetic standpoint. Finally, ~X 13 the problem of positioning and maintaining the spacer rods in ; 14 position at the medial location within the panel during fabrication remains. The length of the sealing rods must be limited since ~ ; 16 they may tend to impede the flow of gas particles and metastables .i,, 17 between adjacent areas separatea by such spacer rods. Thus there 18 is need for a spacer technology which will provide uniform spacing 19 between glass plates particularly in gaseous discharge devices ,.~ 20 having large display areas of high resolution. It would also be ~ 21 desirable to minimize the size of the spacer elements and at the .... . .
22 same time provide greater latitude in their location for aes-~-~ 23 thetic reasons so so they will not be visible and mar the display 24 area.
, 25 Summary of the Invention 26 Toward this end and according to the present invention, ~ 27 applicants have found that these objectives can be achieved by s 28 an improved gaseous discharge display and/or memory device and 29 method which insofar as known has never heretofore been proposed.
In this device and according to applicants' improved spacing Ki974023 o -3-:,-. . -;,~

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10~(193~3 1 method, the plates are held precisely spaced at preselected, 2 constant distances by metallic spacer elements which are 3 attached directly to the metallic conductors prior to the re-flow of dielectric over the conductor arrays. In one embodiment using only drive lines, the spacers could be positioned at ' 6 locations not required for display such as the area between adjacent conductors in the vertical direction or the area be-8 tween rows of conductors in the horizontal direction. In another , g embodiment of the inven~ion utilizing drive lines interspersed 10 by shield lines as taught in the aforenoted Lay patent 3,666,981, r 11 the spacers may be attached directly to the shield lines and 12 will not affect the display. The size of the spacer elements 13 is controlled so as not to impede the flow of charge particles 14 within the panel, and the number and location of the spacer 15 elements may be selected or varied in accordance with the 16 geometry of the panel. Various metals may be used for the spacer 17 elements and conventional techniques are known in the art for 18 attaching the metallic spacer elements to the conductors.
19 Accordingly, a primary object of the present invention is to 20 provide an improved means and method for maintaining a pre-21 determined uniform distance between the plates of a gas panel 22 assembly.
23 Another object of the present invention is to provide an 24 improved spacer technology for a gaseous discharge display ' 25 and/or memory device.
26 Another object of the present invention is to provide an 27 improved spacer technology using metallic spacers attached to s 28 conductor arrays which can accommodate panels of varying size ~- 29 and geometry and which are normally not possible on the display.
30 The foregoing and other objects, features and advantages Ki974023 !

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1 of the pxesent invention will be apparent from the following 2 more particular descrip-tion of preferr~ embodiments of the 3 invention as illustrated in the accompanying drawings.
4 Brief Description of the Drawing :. _ Fig. 1 is an enlarged plan view of a portion of a gaseous 6 discharge display device illustrating one embodiment of the 7 present invention.
8 Fig. 2 illustrates a sectional view of the device shown in g Fig. 1 taken along the lines to 2-2 of Fiy. 1 Des_r ption of a Preferred Embodiment

11 Referring now to the drawings and more particularly to

12 Fig. 1 thereof, there is illustrated a schematic plan view of

13 a portion of a gas panel display. The gas panel assembly of

14 the instant invention corresponds generally to that shown and described in the referenced Haberland et al patent 3,837,724, 16 and the fabrication details are similar except as they relate 17 to details of the instant invention pointed out below. The 18 illustrated section comprises a matrix of horizontal and vertical 19 lines including horizontal lines 13-20 and vertical lines 23-31 respectively. The conductor arrays for such devices, typically 21 utilize the same space between conductors as the conductor 22 width, and a representative width is 4 mils. The horizontal 23 lines 13-20 comprise the upper conductor array and are mounted ., .
24 on substrate or plate 3, while the vertical lines 23-31 comprise the lower conductor array mounted on substrate 5 (~ig. 2). In 26 a gas panel fabrication, conductor arrays are formed of the 27 respective glass plates or substrates, and in one preferred `
28 embodiment (Haberland et al 3,837,724) comprise chrome-copper-29 chrome conductors in which the intermediate coppex layer functions as a conductor, the layer adjacent to the glass plate Ki974023 , , ,...

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1 provides adhesion to the plate and the other chrome layer 2 protects the copper from attack by the active glass components 3 during the fabrication process. Alternatively, conductors of 4 gold, aluminum, nickel or various alloys could be suitably 5 employed.
6 In the illustrated embodiment of the invention, metallic 7 spacers such as spacers 33, 35, and 37 are formed on associated 8 vertical conductors 23, 25, and 30 respectively. The metallic 9 spacers, which might comprise nickel for example, may be 10 attached directly to the associated conductors by any of 11 various conventional processes for metal-to-metal bonding such 12 as thermo-compression bonding, ultrasonic compression bonding, s 13 stitch bonding, etc. In terms of actual size, the conductors ; 14 in a typical gas panel configuration might be 4 mils wide with

15 a 4 mil gap between lines. Accordingly, the spacers in the ;~ 16 illustrated embodiment are slightly less side than their ~ 17 associated conductors for ease of placement, and could be in .~ .
18 ribbon wire form. It should be emphasized that the drawings 19 of the instant application are not to scale but are merely a 20 schematic representation of the conductor arrays of a gas 21 panel and are not intended to portray specific parameters re-22 lating to conductor size, resolution or other structural 23 details of a gas panel assembly which are well known in the 24 art. Preferably extra lines such as vertical lines between 25 characters or horizontal lines between character rows are used :-26 for placement of the spacers. Depending on panel construction, 27 additional lines could be incorporated in the conductor array 28 configurations for this purpose. While the spacers are shown 29 mounted on the vertical drive lines in the illustrated embodi-30 ment, the spacers could alternatively be mounted on the Ki974023 ,:, .
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1 horizontal drive lines or on both sets of lines. Likewise, 2 while the preferred embodiment is shown with individual spacers ~" 3 mounted on a single substrate, the invention could comprise ' 4 metallic spacers of half the gap as spacers 33 mounted on S corresponding positions on opposite sides of the panel whereby 6 the sum of the two spacers is equal to that of the desired gap 7 between panel walls. Further, the specific design of the 8 spacer is not material, and spacers could be formed in a disk , ~ 9 or square configuration. In either embodiment the disk diameter ~ .
or side of the square would be slightly less than the conductor 11 width.

12 With respect to the size of the conductors relative to 13 that of the spacers, a relative but not precise variation is 14 shown in Fig. 2. Conductor thickness such as described by Haberland et al 3,837,724 might be typically 20-25 Microns or

16 approximately 1 mil, while the height of the spacer is typically

17 4 mils to provide a 4 mil gap. As shown more clearly in Fig. 2, .... .

18 when spacers 33, 35 and 37 are fastened to conductors 23, 25 and

19 30 respectively, a layer of dielectric 31 is applied by spraying or some suitable technique and reflowed such that the dielectric 21 layer across the top of the spacer corresponds substantially to 22 the thickness of the dielectric layer over the conductor array.

23 The sectional view in Fig. 2 illustrates that dielectric layer . .
24 41, formed over the vertical conductor array, is also formed over spacers 33, 35 and 37 such that a uniform gap between the 26 two dielectric layers 41 and 43 is provided. By using malleable 27 wire for the spacer elements rather than glass rods, cracking 28 or crazing which occurs with glass spacer rods together with the 29 associated resulting impurities within the viewing area caused by these particles is eliminated.

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1 As previously noted, techniques for bonding metallic 2 spacers to conductors are well developed, and placement of the 3 spacers on the conductor arrays could be controlled by a modified 4 X-Y table with a wire bonding head to place the spacers at the 5 desired locations under digital programming control, the same `' 6 technique employed in artwork. The only requirement relative to 7 positioning other than that defined above is that the spacers 8 must not be long enough or so closely positioned that they inter-r, 9 fere with the normal flow of charge particles and metastables 10 which is essential to gas panel operation. This represents the 11 only limitation on number and placement of spacers.
.;i 12 Description of Alternate Embodiment , .
13 In addition to the preferred embodiment illustrated and : 14 described above, another arrangement for providing a high reso-.
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15 lution panel would utilize a panel of the type disclosed in the 16 referenced Lay patent 3,666,981. In this embodiment, shield f 17 lines are positioned between the normal conductor lines in an 18 alternate configuration on one or both conductor arrays, and 19 the shield lines are connected to a source of common potential.
.... .
~i 20 Using this configuration, the spacers are positioned on the 21 normal shield lines which-are not involved in the discharge 22 but positioned adjacent thereto, are invisible to an observer 23 and do not interfere in any manner with the normal flow of 24 metas~ables and charge particles within the panel.
It is to be understood that the conductor configuration 26 and composition, the specific method of fabrication and the ;~ 27 apparatus by which the chamber 23 is evacuated and then 28 charged with illuminable gas are known in the art and disclosed ~-, 29 for example the above referenced Langston et al patent 3,778,127 30 and Haberland et al 3,837,724. Accordingly such details have Ki974023 ~, ':., v~

`~ 106093~3 i been omitted in the instant application since they are not.

2 considered necessary for an understanding of the present 3 invention.
4 While 'che invention has been shown and described with reference to preferred embodiments thereof, it will be under-6 stood that various substitutions and changes in form and detail 7 may be made by those skilled in the art without departing from 8 the spirit and scope of the invention. Accordingly, the gas 9 discharge display and/or memory device herein disclosed and the method of making same are to be considered as merely illustrative 11 and the scope of the invention is to be limited only as specified 12 ln the claims.

13 What is claimed is:

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A gaseous discharge display device comprising in combi-nation, a pair of glass plates, said glass plates including a substrate with a plurality of parallel conductors fGrmed thereon and overlaid with a dielectric coating, means for sealing said plates in superimposed spaced parallel relation with said dielectric surfaces adjacent to provide a sealed chamber containing an illuminable gas, the conductors on one of said plates being substantially orthogonal to the other and, spacer means for maintaining said dielectric surfaces precisely spaced at a preselected constant distance, said spacer means comprising a plurality of metallic spacer elements positioned on predetermined conductors at non-display locations within said chamber, the height of said spacer elements corresponding to said preselected constant distances, the geometric configuration of said spacer elements being adapted to fit on said conductor but not restrict the flow of gas partieles within said sealed chamber.

2. A device of the type claimed in Claim 1 wherein said spacer elements are attached to said predetermined conductors and also overlaid with said dielectric coating.

3. A device of the type claimed in Claim 1 wherein said metallic spaeer elements are located on non-display portions of said panel.

4. A device of the characters claimed in Claim 3 wherein said metallic spacer elements are comprised of malleable wire.

5. A device of the type claimed in Claim 3 wherein said non-display locations correspond to non-display lines in said plurality of conductors.

6. A device of the type claimed in Claim 5 wherein said geometric configuration of said metallic spacer elements is rectangular.

7. A device of the type claimed in Claim 5 wherein said geometric configuration of metallic spacer elements is disk shaped.

8. A method of fabricating a glass discharge device comprising the steps of, providing two substantially transparent members each with conductor arrays thereon, attaching a plurality of metallic spacer elements to selected conductors in at least one of said arrays whereby said spacers are disposed at predetermined positions on said member to maintain a uniform discharge gap between said trans-parent members, applying a coating of dielectric material over said conductor arrays including said spacing members, disposing heat fusible sealing material over the dielectric material on the border regions of one of said transparent members, positioning said second transparent member on said first transparent member whereby said conductor arrays on said transparent members are substantially orthogonal, and heating the assemblage of said transparent members above the softening point of said heat fusible sealing material to create an impermeable chamber for confining a predetermined volume of gas whereby the height of said spacer elements controls said discharge gap between said members.

9. A method of the character claimed in Claim 8 wherein said spacer elements are attached to non-display areas of said conductors.

10. A method of the type claimed in Claim 7 wherein said metallic spacer elements are attached to both conductor arrays at orthogonal intersections thereof.