US 3619698 A
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Description (OCR text may contain errors)
United States Patent Inventor Bernard Caras Princeton, NJ. Appl. No. 8,773 Filed Feb. 5, 1970 Patented Nov. 9, 1971 Assignee Burroughs Corporation Detroit, Mich. Continuation-impart of application Ser. No. 850,841, Aug. 18, 1969, now abandoned.
DISPLAY PANEL 9 Claims, 13 Drawing Figs.
U.S. C1 313/210, 313/114, 313/220, 313/169 R 1nt. Cl 1-101j 61/30 Field of Search 313/109,
109.5,110, 113, 210, 217, 220; 315/169 R, 169 TV  References Cited UNITED STATES PATENTS 2,555,749 6/1951 Krefft 313/109 2,216,220 10/1940 Baker 313/220 X Primary Examiner-Raymond F. Hossfeld Attorneys-Kenneth L. Miller and Robert A. Green ABSTRACT: A display panel includes a plurality of gas-filled cells which comprise apertures in an insulating plate, and each cell has a cathode at its lower end and an anode at its upper end, from which light exits to a viewer. The walls of the cells are made of light-reflecting material so that nonaxial light rays generated at each cathode reflect back and forth upwardly along the cell walls and exit at different angles. With light rays thus exiting at a wide range of angles, an effective wide viewing angle is presented to a viewer. The surface of the apertured plate which faces the viewer is also light-absorbent to minimize light reflection therefrom toward the viewer.
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DISPLAY PANEL This application is a continuation-in-part of application Ser. No. 850,841, filed Aug. 18, 1969, now abandoned.
BACKGROUND OF THE INVENTION Display panels comprising a plurality of gas-filled cells which can be turned on selectively to display a message are well known in the an. In a recent development, a display panel has been constructed having an array of gas-filled cells which have glow cathodes at their lower ends and anode electrodes at the upper ends facing a viewer. These devices have been built and operated successfully, and they have a satisfactory viewing angle; however, the present invention provides still greater viewing angle and optical efficiency.
SUMMARY OF THE INVENTION Briefly, according to the invention, a display panel includes a plurality of light-generating cells whose walls efficiently utilize light generated at the cathodes regardless of the angle at which it is generated, and the panel has an effective wide viewing angle. In addition, the panel is constructed to have improved contrast ratio and optical efficiency.
DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a display panel embodying the invention;
FIG. 2 is an exploded view of the panel of FIG. 1;
FIG. 3 is a sectional view along the lines 33 in FIG. 1;
FIG. 4 is a sectional view along the lines 4-4 in FIG. 1;
FIGS. 5 to 9 show different modification of a portion of the panel of the invention;
FIG. 10 is a sectional view of a modification of a portion of the invention;
FIG. 11 is a sectional view of another modification of a portion of the invention;
FIG. 12 is a sectional view of another modification tion of the invention; and
FIG. 13 is a sectional view of a single display cell which illustrates the effectiveness of the invention in providing a wide viewing angle.
of a por- DESCRIPTION OF THE PREFERRED EMBODIMENTS A display panel 10 embodying the invention includes a first insulating plate of glass, ceramic, or the like having a plurality of parallel slots or channels formed therein and extending from the top surface 40 to close to the bottom surface 50 thereof. For purposes of illustrating and describing the invention, the panel is oriented so that the slots extend horizontally. The slots may have any suitable cross section. A V- shaped cross section is shown in FIGS. 2 to 4; however, any other suitable cross section may be employed. For example, a rectangular or square cross section is shown in FIG. 5, and, in FIGS. 6 and 7, the slot has a narrow upper portion and an enlarged lower portion. In FIG. 8, a slot has a wide upper portion and a narrower lower portion, and in FIG. 9, a slot has a generally inverted V shape.
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, flat strips, or they may have any suitable shape, depending on the shape of the slot. These electrodes might also be plated or evaporated or otherwise formed in the slots. The electrodes 60 might also be secured by a cement such as a glass frit or the like at the ends of slots 30 or at any other suitable location.
The panel also includes second electrodes 70 seated on the top surface 40 of the first plate 20. The second electrodes 70 are also parallel to each other, and they are oriented perpendicular to the first electrodes 60. The electrodes 70 are preferably flat strips, and they may also be seated in slots 80 formed in the top surface 40 of the plate 20, as illustrated in FIG. 2, or in slots in the second insulating plate ll0 which is disposed above them. The region at which each second electrode 70 crosses a first electrode 60 defines a gas cell 90, and each electrode 70 has an aperture at this region if it is a flat strip, or it is suitably shaped or offset, or the like to provide a small communication opening from electrode 60 through electrode 70 to other elements disposed above the electrodes 70 (to be described).
The second insulating plate 110, having a plurality of apertures or cells 120 arrayed in rows and columns, is seated on the top surface of plate 20, with each aperture or cell aligned with a cell 90 which is 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 plate may be of any suitable dielectric material such as glass, ceramic, or the like, and the holes or cells may be cylindrical, or they may have any other suitable shape.
In a preferred construction, the apertures of plate 110 have light-reflecting walls. This permits nonaxially directed light generated at a cathode electrode 70 in cells I20 to reflect back and forth and exit at different angles such that the overall viewing angle of the panel is improved. In addition, the top surface of plate 110 is rendered light-absorbent by being darkened or blackened or the like to prevent or minimize ambient light reflections. A black glaze or black frit or the like which will not interfere with panel operation can be used for this purpose. For this preferred construction, the plate 110 may be made of many light-reflecting insulating materials such as alumina, fosterite, steatite, white glass, boron nitride, beryllium oxide, mullite, or Opal glass, all of which provide the desired light-reflectivity in the cells 120.
In other embodiments of the invention, the top surface of plate 110 may be covered with a light-absorbent sheet 190 (FIG. 10) of, for example, black mica, black glass or the like, rather than a light-absorbent coating. Plate 110 might also be made of a metal sheet 194 coated with a film 196 of insulating material such as porcelain, glass, or the like (FIG. 11) suitably colored to be light-absorbent. Also, in plate 110, the walls of cells 120 could be coated with a light-reflecting material 200 such as chromium or the like, as illustrated in FIG. 12.
Referring now to other features of panel I0, third electrodes are seated on the upper surface of the apertured plate 110, and they are preferably embedded either in slots in plate 110 or in a transparent cover plate or viewing plate I50 which is seated on plate 110. The electrodes 130 are oriented parallel to the first electrodes 60, and each is aligned with a row of apertures 120 in the plate 110. The electrodes 130 may also be flat strips or wires or the like, and they are either apertured, or they are otherwise suitably shaped so that a viewer looking through top plate can look into the cells 120.
In panel 10, the electrodes 60, 70, and 130 may be secured in place by means of a suitable cement such as a glass frit (not shown). They might also be held in place by a mechanical tight fit in slots or grooves in the plates which they lie between. In addition, in the completed device, the plates 20, 110, and 130 are sealed together at their edges by means of a mass of glass frit or the like 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 110, as shown in FIGS. 2 and 3. This arrangement is not required, however.
Panel 10 also includes an ionizable gas such as argon, neon, or the like, or mixtures of gases and a small quantity of mercury, all at a suitable pressure for the intended purpose. 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 advantage of the invention with respect to improving viewing angle is illustrated schematically in FIG. 13, which shows a typical cell in which cell glow appears at the cathode at the base of the cell. Assuming that there is little or no light reflection from the walls of the cell, the light rays A, which