US3739218A

US3739218A - Display panel having metal cell sheet

Info

Publication number: US3739218A
Application number: US00089549A
Authority: US
Inventors: T Maloney
Original assignee: Burroughs Corp
Current assignee: Unisys Corp
Priority date: 1970-11-16
Filing date: 1970-11-16
Publication date: 1973-06-12
Anticipated expiration: 1990-06-12

Abstract

A display device including a plurality of communicating gasfilled display cells arrayed in a panel structure. A first layer includes a first plate having grooves in it, with first electrodes seated in the grooves, and second electrodes supported across them. A second layer includes a metal plate or sheet electrode having apertures in it and being insulated from the second electrodes and from third electrodes which are disposed above it. The first and second electrodes cross beneath the apertures and the third electrodes lie above the apertures, which serve as the display cells of the device.

Description

waited States Patent 1 1 1 1 3,739,218

Maloney 1 June 12, 1973 DISPLAY PANEL HAVING METAL CELL 2,858,480 10/1958 Shadowitz 315/169 Tv SHEET FOREIGN PATENTS OR APPLICATIONS 1751 lnvenwrl Tlwmas Mamney Bernardsville, 1,198,568 7/1970 Great Britain 313/1095 [73] Assignee: Burroughs Corporation, Detroit, Primary Examiner Palmer C. Demeo Mich. Att0rneyl(enncth L. Miller, Robert A. Green, George [22] Filed Nov 16 1970 L. Kensinger and Charles S. Hall [21] Appl. No.: 89,549 [57] ABSTRACT A display device including a plurality of communicat- [52] g} 32 45 215 4; 1, ing gas-filled display cells arrayed in a panel structure. [51 I t Cl HOT 61/04 A first layer includes a first plate having grooves in it, g i 220 with first electrodes seated in the grooves, and second electrodes supported across them. A second layer includes a metal plate or sheet electrode having apertures in it and being insulated from the second electrodes [56] References Cited and from third electrodes which are disposed above it.

UNITED STATES PATENTS The first and second electrodes cross beneath the aper- 3,612,938 10/1971 De Boer et a1. 313/1095 tures and the third electrodes lie above the apertures, 3,096,516 7/1963 Pendelton et al. 315/169 TV which erve as [he cells of the device 2,925,530 2/1960 Engelbart 3l5/84.6

2,848,638 8/1958 Smith 313/1095 13 Claims, 5 Drawing Figures Patented June 12, 1973 3,739,218

2 Sheets-Sheet 2 INVENTOR. THOMAS C MALONEY ATTORNEY DISPLAY PANEL HAVING METAL CELL SHEET BACKGROUND OF THE INVENTION Display panels comprising a plurality of gas-filled cells which can be ionized selectively to display a message are known in the art. A display panel has been developed recently which has two layers of communicating cells, a first layer being used as a scanning or addressing layer for sequentially addressing the display cells, one by one or column by column, and a second layer into which information is inserted to be displayed, and perhaps stored, as the first level is scanned. These multi-layer devices have been constructed of several layers of glass or other insulating material with groups of thin wires or strip electrodes suitably positioned between them, in alignment with a matrix of closely spaced apertures in a glass or ceramic center sheet which serve as the gas cells.

The apertured center sheet defines the display cells and spaces the display control electrodes from the cathodes, a group of electrodes common to both the scanning cells and the display cells and usually separating the two groups of cells. The center sheet usually must be relatively thick in order to provide an adequate potential threshhold for ionization or breakdown and suitable glow in the display cells. The center sheet also must be thick enough for fabrication and assembly when the cells are spaced close to each other. The center sheet usually comprises glass or ceramic formed or drilled to provide the necessary apertures, which is expensive.

The apertures in the center sheet are usually of small diameter and the sheet is generally opaque or is coated with opaque material so that light will be visible only at the activated display cells. This restricts or limits the viewing angle in such devices because the edges of the small apertures in the center sheet increasingly obscure the glow in the display cells as the viewing angle is increased.

It has not been possible to reduce the thickness of the glass or ceramic center sheets enough to improve adequately the viewing angle of the display. With given operating potentials applied to the electrodes of the device, the center sheet has had to be of corresponding thickness in order to provide the desired operational characteristics. Also, the diameter of the holes in the center sheet could not be enlarged too greatly in devices having closely spaced display cells.

These problems are compounded in multiple register display panels such as those described in B. Caras Pat. application Ser. No. 21,125, filed Mar. 19, 1970, now US. Pat. No. 3,654,508. The subject invention is also applicable to improving the angle of view of the display devices disclosed in Ogle et al Patent application Ser. No. 850,984 and in J. A. Ogle application Ser. No. 855,448, both tiled Aug. 18, 1969.

SUMMARY OF THE INVENTION Accordingly, it is an object of this invention to provide a display panel of thin construction and of increased viewing angle.

Another object of the invention is to reduce the cost of apertured center sheets for multi-layer display devices and to increase the effective threshhold potential for ionization of the cells.

A further object of the subject invention is to provide a multi-layer cellular display panel in which the apertures forming the cells can be shaped for better viewability and spaced closer together.

Briefly, a gas-filled display panel embodying the subject invention includes a plurality of insulating plates and electrode arrays interleaved to provide rows and columns of display cells and electrodes for operating them. The top and base plate of the panel structure is of glass or ceramic, as desired, and a center sheet separating the layers of cells is formed of metal or other conductive material insulated from the electrodes on either side of it.

In operation of the display device, the conductive center sheet usually assumes a potential intermediate the operating potentials applied to the display cell electrodes. According to a feature of the invention, terminal leads may be provided from the center sheet for applying a potential thereto or for monitoring the potential on it, if desired.

Other objects, advantages and features of the invention will become clear from the following description of the preferred embodiments, wherein:

FIG. 1 is a perspective view of an information display device suitable for practicing the invention;

FIG. 2 is an exploded view illustrating the internal construction of an exemplary display panel incorporating the invention;

FIG. 3 is a sectional view showing an elevation of the display device of FIG. 1 taken at 3-3;

FIG. 4 is a sectional view showing an elevation of the display device of FIG. 1 taken at 44; and

FIG. 5 is an enlarged sectional view of a display position showing another embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 to 4, a display panel 10 embodying the invention includes a first insulating plate 20 of glass, ceramic, or the like having a plurality of parallel slots, grooves or channels 30 formed therein and extending from the top surface 40 toward the bottom surface 50 thereof. For purposes of illustrating and describing the invention, the panel is oriented so that the slots extend horizontally. Relatively few slots have been shown, to simplify the drawing, but it should be understood that, in most applications, plate 20 would be considerably wider and would have many more slots in it. The slots may have any suitable cross-section.

First electrodes 60 are seated at the bases of the slots and, since the slots are parallel, so are the electrodes. Electrodes 60 may be wires or strips of any suitable shape, secured by a cement such as a glass frit or the like at the ends of slots 30 or at any other suitable location. These electrodes may alternatively be plated or evaporated or otherwise formed in the slots.

The panel also includes second electrodes seated on the top surface 40 of first plate 20. The second electrodes 70 are also parallel to each other, and they are oriented generally perpendicular to the first electrodes 60, although they can be skewed. The electrodes 70 may also be flat strips or wires or the like, and they may be seated in slots (not shown) formed in the top surface 40 of plate 20, if desired. The region at which each second electrode 70 crosses a first electrode 60 defines a gas cell 90. Each electrode 70 has an aperture at this region if it is a flat strip, or it is'suitably shaped or offset, so that communication can take place from electrode 60 through or around electrode 70 to other elemerits disposed above electrodes 70 (to be described).

A second insulating plate 100 having a plurality of apertures or cells 120 arrayed in rows and columns is seated on the top surface of the electrodes '70 with each aperture or cell aligned with an aperture 75 and with a cell 9% defined by a crossing of a second electrode 70 and a first electrode 60. Each aperture 120 .thus comprises a cell which is vertically aligned with a cell 90 formed by the first and second electrodes and the portions of the slot 30 between them.

The insulating plate W is composed of a metal sheet lllltl having an insulating layer 105 on its bottom side and an insulating layer 1 115 on its top surface. The holes or apertures 120 for the display cells extend through the three layers of plate M0 in registration with apertures 75 in second electrodes 70. These apertures 120 are cylindrical in shape and expose metal sheet 110 to the display cells in one preferred embodiment, as shown in FIGS. 3 and 4. Metal center sheet IN) is provided with terminals or leads i112 and 114, either or both of which may be used for applying a bias potential in the region of the display cells or for electrically monitoring the operation of the cells. The metal center sheet thus serves as an auxiliary electrode of the device in establishing contact with the electric fields and electric discharges in the cells. Such a bias potential can raise or lower the ionization potential threshhold depending upon its polarity.

Insulating plate 100 is less brittle than all glass or all ceramic center plates due to the support of metal center sheet 110. It may, therefore, be made thinner than corresponding glass or ceramic plates having the same number of apertures of the same diameter and still having adequate structural strength. In practice, insulating

layers

105 and 115 are considerably thinner than metal center sheet 110 and serve as insulating coatings on the surfaces of the metal sheet. Furthermore, the use of a thinner center plate 100 may be allowed for electrically, by the application of a suitable bias potential to metal center sheet electrode 110. The application of such a bias potential to center

sheet electrode terminal

112 or 114, or both, can raise the effective ionization potential threshhold in the display cells. This permits a thin center plate 100 to insulate and isolate the display cells from the scan control electrodes as effectively as a thicker glass or ceramic center plate.

The holes or apertures in insulating center plate 200 may alternatively be conical in shape and may expose the metal center sheet, or may leave it insulated, as shown in FIG. 5. Metal center sheet 210 has apertures 220 in the shape of truncated conical holes formed in it and the edges of the apertures, together with the top and bottom surfaces, are coated with an insulating layer 225. Conical holes may be produced in the center sheet by controlled chemical etching of the sheet, for example, and insulating layer 225 may be applied to it after the holes are formed.

Insulation layers 105 and 115 are preferably insulating coatings applied to center sheet 110 after apertures 12b have been formed in it, although insulating sheets having appropriately positioned apertures in them may also be employed. Insulating coatings H05 and 1115 may be of ceramic or glass, such as fosterite, applied by spraying. Any other suitable glass, ceramic or the like may be applied to the surfaces of the metal center sheet as insulating

layers

105 and 115 or 225. The insulating coating may be applied by dipping center sheet MO or be applied to the surfaces of metal center sheets or 210.

In each case, the insulating coating is applied to the metal center sheet after the apertures in it have been formed, although this is not necessary since the holes could be formed by drilling or punching through the three layers of the plate. Transfer coatings of glass or like material may be applied to a metal sheet in which the apertures have been already formed. The assembly then is baked in an oven at a temperature sufficient to cause the surface tension of the heated transfer layer to open up apertures in the transfer coating layers over the apertures in the metal sheet.

The groupings of cells 90 in lower plate 20 along the slots 30 are referred to herein as rows of cells or apertures, and those in line with electrodes 70 as columns.

Third electrodes 130 are seated on the upper insulating layer of the apertured plate 100. The electrodes 130 are oriented parallel to and aligned with the first electrodes 60, and each is aligned with a row of apertures in insulating plate 100. The electrodes 13 may also be flat strips or wires or the like, and they are either apertured or otherwise suitably shaped, so that a viewer looking through top plate 150 will see the glow discharges which occur in cells 120.

In panel 10, the

electrodes

60, 70 and may be secured in place by means of a suitable cement such as a glass frit (not shown). In the completed device,

plates

20, 100, and are sealed together at their edges by means of a glass frit or the like 25 shown in FIGS. 3 and 4. For convenience in making this seal, top plate 150 and bottom plate 20 are usually made somewhat larger than center plate 100, also as shown in FIGS. 3 and 4.

Panel 10 also includes an ionizable gas such as argon, neon, or the like, and preferably a Penning mixture of such gases, including a small quantity of mercury, all at a pressure suitable for the desired discharge. The gas may be introduced by means of a tubulation (not shown) suitably secured to the panel, or it may be introduced in any other suitable manner.

The operation of multi-cell display panels such as panel 10, in which slots 30 operate as gas communication paths between adjacent cells, is described in detail in a co-pending application of Ogle and Holz, Ser. No. 850,984, filed Aug. 18, 1969, and reference is made to that application for a complete discussion of the operation. Briefly, in the operation of the device,

electrodes

60 and 130 preferably serve as anodes and electrodes 70 as cathodes. Also, successive cathodes 70 are electrically connected together so as to form three or more alternating

electrode sets

70a, 70b, and 700, and each of the electrode sets is connected to a driving source (not shown). The lower cells 90 are scanned columnby-column by sequential energization of the alternating cathode sets 70, and glow is produced in each column of cells 90 in turn. This sequential energization is repeated until the entire panel 10 has been scanned, and then continued so that the panel is scanned repetitively.

Since plate 20 is slotted, gas communication is provided between the adjacent columns of cells. As a consequence, when one column is glowing, it serves to prime the two adjacent columns. It is the presence of this selective priming which permits the cells in plate 20 to be scanned column-by-column using only three or more driving sources, as desired.

Simultaneously with the scanning, and synchronously with the scanning rate, information signals are applied to the anode electrodes 130. Where ON signals are present on selected anodes, glow is transferred upwardly into cells 120, at an intensity determined by the level of the ON signals, to display a visible message. As each column of cells is scanned in turn, and information signals are applied, a stationary but changeable display is distributed to the columns of display cells 120 and is visible through the top plate. The glow present in the lower cells 90, however, is not visible through the top plate, so that the internal scanning operation in the panel does not interfere with the display.

Although the preferred embodiments of the invention have been described in detail, it should be understood that the present disclosure has been by way of example only. Many modifications and variations of the invention are possible in light of the above teachings. It is, therefore, to be understood that the invention may be practiced otherwise than as specifically disclosed.

What is claimed is:

l. A display panel comprising a first insulating plate having top and bottom surfaces,

a plurality a first elongated electrodes disposed parallel to each other along the top surface thereof,

a plurality of second electrodes spaced from the first electrodes and oriented at an angle to said first electrodes and crossing a plurality of them,

a flat conductive member spaced from the second electrodes and having a plurality of apertures arrayed in a matrix, each aperture being aligned with a crossing of a second electrode and a first electrode and defining a gas cell, i

a plurality of third electrodes spaced from the conductive member and from the second electrodes in alignment with a group of said apertures and the portions of the first and second electrodes which cross beneath them,

a second insulating plate situated parallel to the first plate, one of which being light transmissive, with the electrodes and the conductive member positioned between them, and

a gaseous atmosphere sealed in the region between the insulating plates and including an ionizable gas at a pressure capable of sustaining cathode glow discharge.

2. The display panel of claim 1 wherein the first insulating plate has a plurality of parallel grooves therein extending down from the top surface and each of the first electrodes is disposed in one of said grooves.

3. The display panel of claim 1 wherein the second electrodes comprise a plurality of flat conductors which substantially cover the associated apertures in said flat conductive member except for a small opening or an aperture in them at each gas cell to allow for priming of the cells.

4. The display panel of claim 1 wherein the flat conductive member carries an insulating layer which spaces it from the second and third electrodes.

5. The display panel of claim 1 wherein the third electrodes are elongated and are oriented in the same direction as the first electrodes, the second electrodes being elongated and crossing at least some of them.

6. The display panel defined in claim 5 wherein the first and third electrodes comprise conductive wires and the second electrodes comprise elongated flat strips having apertures at the regions where the second electrodes cross the first electrodes to allow for priming of the cells.

7. The display panel of claim 1 wherein the flat conductive member comprises an apertured metal sheet electrode carrying an insulating layer on its top and bottom surfaces and having an electrode terminal adapted for connection to biasing or monitoring apparatus.

8. A display device having a plurality of gas-filled display cells adapted to be energized singly or in groups to display a character or message comprising:

insulated housing means containing a gaseous atmosphere at a pressure capable of sustaining cathode glow discharge and having a light-transmitting window,

a conductive member situated in said housing and having a plurality of apertures spaced apart in at least one surface thereof for defining individual display cells,

first and second electrode means associated with each of the cells for recurrently ionizing the gas adjacent them, and

third electrode means associated with the display cells for selectively ionizing the gas in the cells and causing glow discharge in them.

9. The display device of claim 8 wherein the first and second electrodes comprise elongated conductors which cross each other at an angle adjacent the apertures in said conductive member.

10. The display device of claim 8 wherein the conductive member comprises a flat sheet having apertures through it, the first and second electrode means comprising a set of anodes spaced from one side of the sheet and the third electrode means being situated adjacent the other side of the sheet.

11. The display device of claim 8 wherein the conductive member comprises a flat metal sheet having apertures through it with larger openings adjacent the third electrode means than the openings adjacent the first and second electrode means.

12. The display device of claim 8 wherein the conductive member comprises a flat conductive layer carrying an insulating layer which spaces it from the electrode means.

13. The display device of claim 8 wherein the conductive member comprises an apertured metal sheet bearing an insulating coating on both sides, the first and second electrode means crossing each other at the cells adjacent one side of the sheet and the third electrode means being situated adjacent the other side of the sheet.

* l i I I

Claims

1. A display panel comprising a first insulating plate having top and bottom surfaces, a plurality a first elongated electrodes disposed parallel to each other along the top surface thereof, a plurality of second electrodes spaced from the first electrodes and oriented at an angle to said first electrodes and crossing a plurality of them, a flat conductive member spaced from the second electrodes and having a plurality of apertures arrayed in a matrix, each aperture being aligned with a crossing of a second electrode and a first electrode and defining a gas cell, a plurality of third electrodes spaced from the conductive member and from the second electrodes in alignment with a group of said apertures and the portions of the first and second electrodes which cross beneath them, a second insulating plate situated parallel to the first plate, one of which being light transmissive, with the electrodes and the conductive member positioned between them, and a gaseous atmosphere sealed in the region between the insulating plates and including an ionizable gas at a pressure capable of sustaining cathode glow discharge.

8. A display device having a plurality of gas-filled display cells adapted to be energized singly or in groups to display a character or message comprising: insulated housing means containing a gaseous atmosphere at a pressure capable of sustaining cathode glow discharge and having a light-transmitting window, a conductive member situated in said housing and having a plurality of apertures spaced apart in at least one surface thereof for defining individual display cells, first and second electrode means associated with each of the cells for recurrently ionizing the gas adjacent them, and third electrode means associated with the display cells for selectively ionizing the gas in the cells and causing glow discharge in them.