JPS6310687A - Display phospholuminescent substance of electroluminescence having lowering inclination to continuous molding - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION BACKGROUND OF THE INVENTION The present invention relates to electroluminescent displays.
The present invention relates to a phosphorescent material for use in o-luminescent displays. In particular, zinc sulfide powder phosphor material is used in matrix display panels such as working panels or segmented display panels in direct current mode.
) relates to an improvement in the phosphorescent layer of an electroluminescent display panel; it also relates to something that can be applied to a working display panel in an alternating current mode.

Electroluminescence is the emission of light from a crystalline phosphorescent material by the application of an electric field. A commonly used phosphorescent material is zinc sulfide which has been activated by incorporating up to 1 mole percent of various elements, such as manganese, into its lattice structure. When such materials are subjected to an electric field of sufficient magnitude, they emit a color that is characteristic of the composition of the phosphorescent material. Zinc sulfide activated with manganese (hereinafter referred to as zinc sulfide:manganese or ZnS:Mn phosphor)
is centered at a wavelength of 585 nanometers (nm).
tered) Produces a pleasant yellowish-orange color.

ZnS:Mn phosphor has high lumi
nance), luminous efficiency (luminous effc)
ency) and discrimination ratio (discrimination)
ratio) and long service life. Luminance is the brightness or luminous intensity when activated by an electric field, and is usually measured in lamberts, or candelas per square centimeter (pi).
andelas) or foot lambert (foot-1
Luminous efficiency, measured in candelas per square foot, is the light produced, typically compared to the power consumed by the device, measured in lumens per watt (1u+sen per watt). The discrimination ratio is the open voltage amount (“off” voltage)
Closed voltage for brightness corresponding to! (“on” volta
ge).

A wide range of colors can be produced by replacing or supplementing manganese with other substances such as copper or alkaline earth metal activators or by replacing or supplementing zinc sulfide with other similar phosphors such as zinc selenide. can do.

Phosphorescent materials come in a wide variety of electroluminescent forms (electro-IIIin) to serve multiple functions.
the initial configuration). In many electroluminescent devices,
Electroluminescent displays consist of individually activated pixels (picture elements).
The panel is divided into a matrix of re ele++ent)).

The two big 7 minutes of the electroluminescent device are AC
This is a work method for commercial and DC use. In the DC configuration, electrons from the external circuit pass through pixels in the panel; in the AC configuration, the pixels are capacitively connected to the external circuit (
couple
be done.

Electroluminescent devices are also made using powder or thin film phosphor forms. The powdered phosphor is prepared by precipitating crystals of the powdered phosphor of the appropriate particle size, suspending the powder in a lacquer uniform vehicle, and then applying the suspension by spraying, screening or doctor blade coating techniques. Formed by coating. Thin film phosphors are grown from evaporative condensation from vacuum deposition, sputtering or chemical vapor deposition.

Two configurations for which the present invention has a high degree of adaptability are direct current CDC
) is a working powder phosphorescent material electroluminescent matrix and split display panel. Matrix display panels are used in a variety of applications and have found utility as a replacement for cathode ray tubes (CRTs) in most locations where CRTs are used. For example, matrix display panels may be used in applications such as oscilloscopes, television monitors, and convenience store monitors.

A particularly advantageous application for matrix display panels is as a monitor for microcomputers or personal computers. By avoiding the requirement for a CRT, electroluminescent matrix display panels make personal computers more compact and thus more easily transportable.

The segmented display panel can be used to display alpha numbers (alp) in devices such as digital watches; pocket calculators; and petrol pump indicators for price, delivery capacity and delivery quantity prices.
It has been found useful for hanumeric display.

The use of electroluminescent matrix display panels as personal convenience monitors and for various other applications is known.

However, electroluminescent display panels are subject to various types of degradation over time, and sooner or later the panel must be replaced.

U.S. patent application Ser. Disclosed. However, even the substance of the invention “
``further forming'', i.e. further forming in which the progression of the forming process desired to produce luminescence results in a decrease in the capacitance of the phosphor element made of the phosphor. Additive reduction in the trend toward "continuous molding" has been found to be desirable.

It was.

It is therefore an object of the present invention to provide an electroluminescent material for use in electroluminescent display panels with an increased service life, in particular a decreasing tendency to "continuous molding".

SUMMARY OF THE INVENTION A prior art phosphor for use in electroluminescent display panels, such as electroluminescent matrix display panels, (a) contains about 0.1-1.0% by weight manganese; About 0.1~ consisting of zinc sulfide
phosphor particles having a particle size of 2.5 microns; (b) a coating of copper sulfide on the phosphor particles; and (c) a dielectric binder.

The present invention provides an improvement in such phosphors by dehydrating the phosphor to less than 6 micrograms of water per gram of total phosphor and binder. Preferably, the amount of water is reduced to less than 3 micrograms per gram of total phosphor and binder, or even to 2 micrograms.

A preferred method of reducing the amount of moisture to the desired level is freeze drying. Another method, which may be preferred in some cases, is to remove water by simultaneous application of heat and partial vacuum. However, freeze drying is useful in that moisture is removed without heating. Heating can degrade the phosphorescent element, for example by causing undesirable chemical reactions. It has been discovered that freeze drying allows the removal of moisture that cannot be removed by heating alone without deterioration of the phosphorescent element.

It has been discovered that dehydration to the indicated level yields a phosphor that has undergone some "continuation shaping".

Prior art electroluminescent display panels include (1) a transparent, flat, non-conductive substrate; (12) at least one anode applied to one side of the transparent, non-conductive substrate; (3) electrically connected to the anode. A phosphor layer of about 15 to 40 microns thick consisting of at least one phosphor element applied to one side of a transparent, non-conductive substrate in contact, each phosphor element having a thickness of (a) about 0.0 microns; 1-1.0%, preferably 0.4% (weight i
t) consisting of zinc sulfide containing manganese from about 0.1 to
2.5 micron particle size phosphor particles; ('O) a coating of copper sulfide on the phosphor particles; and (c) a dielectric binder; and (4) each comprising a phosphor element. It consists of at least one conductive cathode in electrical contact.

In the case of an electroluminescent matrix display panel, the device comprises (1) a transparent, flat, non-conductive substrate; (2) a number of mutually parallel transparent substrates applied to at least one side of the transparent, non-conductive substrate; a conductive anode; (3) consisting of a number of mutually parallel phosphor elements applied to one side of a transparent, non-conductive substrate in a diagonal direction with a transparent, conductive anode;
In a 5-40 micron thick phosphor layer, each phosphor element contains (a) about 0.1-1.0%, preferably 0.4% (
of zinc sulfide containing manganese (by weight) approximately 0.1
phosphor particles having a particle size of ~2.5 microns; (c) a coating of copper sulfide on the phosphor particles; and (c) a dielectric binder; and (4) each applied to the phosphor element. It consists of a large number of mutually parallel conductive cathodes.

The present invention provides an improvement in such an electroluminescent display panel or an electroluminescent matrix display panel, in which the water content in the phosphor material used in the panel is reduced in grams (grams) of the total phosphor material and binder. 6 micrograms (preferably 3 or even 2) per
The above provides for removal (preferably freeze drying).

Electroluminescent matrix display panels according to the prior art can be manufactured by a method comprising the following steps: (1) applying a number of mutually parallel transparent conductive anodes to one side of a transparent non-conducting substrate; (210, producing a homogeneous powder of zinc sulfide crystals containing about 0.1 to 1.0% by weight of manganese so as to produce crystal grains with a particle size of 1 to 2.5 microns: (3) crystals; immersing the particles in an aqueous salt solution containing a salt selected from the group consisting of copper chloride and copper nitrate to perform surface substitution of zinc with copper to produce zinc:manganese sulfide particles coated with copper sulfide; (4) ) Zinc sulfide coated with dielectric binder, diluent and copper sulfide: sufficient dilution to provide the dielectric binder with a viscosity that allows the mixture of manganese particles to be applied to a transparent, non-conductive substrate. (5) mixing a mixture of dielectric binder and diluent with zinc sulfide:manganese particles coated with copper sulfide; (6) dielectric binder, diluent and sulfide; A mixture of copper-coated zinc sulfide:manganese particles is deposited onto a transparent, non-conductive substrate over parallel transparent conductive anodes, parallel to each other, but at an oblique angle to the parallel transparent conductive anodes. stripe
(7) Zinc sulfide coated with dielectric binder and copper sulfide: Zinc sulfide coated with dielectric binder, diluent and copper sulfide to leave a series of streaks with manganese: evaporating the diluent from the mixture of manganese particles; (8) applying a two-lambda bottle, one cathode over the strip of manganese particles: zinc sulfide coated with a dielectric binder and copper sulfide; and 9) Zinc sulfide coated with a dielectric binder and copper sulfide: the cathode is coated with a dielectric binder and copper sulfide to provide a matrix of electroluminescence pixels with stripes of manganese particles. Zinc sulfide can be produced by a process consisting of passing a sufficient forming current through manganese particles and an anode.

The present invention provides an improvement in such methods by carrying out the final directing step (passing the forming current through the cathode, the zinc:manganese sulfide particles and the anode to form pixels) in a dry box in a dry air atmosphere. then placing the panel in a chamber to which a GO vacuum is applied and an inert gas introduced into it; (11) reducing the temperature of the panel in the chamber to below -10°C, preferably below -30°C; freezing the water in the panel to ice; sublimating the ice in the panel by applying a partial vacuum to the chamber through a vacuum conduit with a shutoff valve and reducing the pressure to an absolute pressure of mercury of less than 25 microns, preferably less than 12 microns; Remove the sublimated ice from the chamber, thereby removing water from the panel; maintain partial vacuum until no more moisture is removed from the panel, typically about 20-60 minutes;
α Close the shutoff valve in the vacuum conduit; α9 Introduce an inert gas, preferably dry helium or argon, into the chamber; αe Backcap the substrate over the anode, phosphor element and cathode, anode with inert gas. , the phosphor element and the cathode are permanently encapsulated using a low permeability cement; aη the seal between the backcap and the substrate is tested for leaks; and αa the pixel response (pixel response)
through the cathode; pixel and anode to produce phosphorescence under normal working conditions until the (generation of phosphorescence in response to the passage of current in the various pixels) is sufficiently uniform, typically 1 to 2 hours. The panel is aged (aglng) by passing an electric current through it.

The dielectric binder can be organic, such as nitrocellulose; or inorganic, such as tin sulfide or ceramic materials.

DETAILED DESCRIPTION The display panel of the electroluminescent matrix shown in FIG. 1 is in a position opposite to that seen by an actual observer. A portion of the panel is shown in FIG. 2 in a vertical position relative to that seen by an actual observer.

Panel 10 consists of a substrate 11 having attached to one side various elements described below. These elements form phosphorescence at the interface between them and the substrate 11. The electroluminescent matrix display panel is intended to be viewed by an observer 12 through the substrate 11 along a line of sight 13 .

The general structure and operation of electroluminescent matrix display panels are known in the prior art; for example, Blect
roluminescent Displays,
(E.L. Tannas.

Ed, Flat-Panel Displays
and CRTs (1984), Chapter 8)
;Vecht, U, S, P, 3,731.
353; Kirton etc., U, S, P,
3,869,646; and Vechtetc, U.
See S.P. 4,140.937.

Although there is additional discussion in U.S.P. Application No. 752.317, filed July 3, 1985 by David Glaser, it is believed that the following discussion may be understood without reference to the prior art.

Substrate 11 is transparent, flat, and non-conductive; preferred materials for substrate 11 are glasses such as soda lime glass and borosilicate glass.

A number of mutually parallel transparent conductive anodes 14 are applied to one side of the transparent non-conductive substrate 11, the anodes 14 being tin oxide or indium-tin oxide.

A phosphorescent layer about 15 to 40 microns thick, preferably about 25 microns thick, consisting of a plurality of mutually parallel phosphor elements 15 is provided on one side of the transparent non-conductive substrate 11. , is applied over the transparent conductive anode 14. The direction of application of the mutually parallel phosphor elements 15 is oblique to the transparent, conductive anode 14, preferably perpendicular.

The phosphor element 15 consists of phosphor particles 16 (Figure 2) with a particle size of about 0.1 to 2.5 microns; and a dielectric binder, the phosphor element 16 having a particle size of about 0.1 to 1.5 microns. 0% manganese, preferably about 0.4% (by weight); zinc sulfide, preferably also about 0.05% copper; and a coating of copper sulfide on the phosphor particles. The dielectric binder is, according to one option, an organic material such as nitrocellulose. Inorganic materials such as tin sulfide or ceramic materials may also be used as mentioned above.

A number of mutually parallel conductive cathodes 17, preferably aluminum, are applied, each cathode 17 being applied to the phosphor element 16, so that the phosphorescent material 16 is applied to all the phosphor elements 16. Element 16 is applied in stripes and cathode 1
7 is applied over the phosphor element 16, the ultimate shape provided to the phosphor element 16, and not the order in which the device is constructed.
The purpose is to specify the position of the cathode 1τ. The phosphor particles and the binder are used as a sheet, and the cathode 17
It is convenient to apply the aluminum as another sheet and then scribe both at the same time to form the phosphor element 16 and the cathode 17. Other methods of simultaneously forming the respective phosphor elements and electrodes are also available and can be used, as is known in the art.

As part of applying the binder, phosphor, and cathode, the steps performed include applying the applied binder, phosphor, and cathode to an area larger than the area that will remain in the final panel. If so, cut the ears (trima+ing)
); and bridging between the cathodes and the ends to which they are connected.

A current is then passed between the cathode 17 and the anode 14, first passing the strips of zinc sulfide:manganese particles coated with an organic dielectric binder and copper sulfide into a matrix of electroluminescent pixels 18. and then cause those pixels 18 to emit light. The current flows through the straightest path between cathode 17 and anode 14, i.e. the orthogonal path of phosphor element 15 within a square bounded at one end by the width of anode 14 and at the other end by the width of cathode 17. Columnar part<square
column part). Each orthogonal columnar portion of such phosphor element 15 is a pixel 1.
It is 8. Each pixel 18 has a time division composite basis for each combination of cathode 17 and anode 14.
They can be independently illuminated by electrical circuits known in the art to sequentially apply the nanomultiplexing basis.

Anode 14 and cathode 17 are each preferably located about 0.25 fl on center apart, yielding a density of about 16 pixels per n square, or 1600 pixels per square value.

Electroluminescent matrix display panel 10
can be manufactured by the following process:! (1) Applying a number of mutually parallel transparent conductive anodes 14, preferably tin oxide or indium-tin oxide, to one side of a transparent non-conducting substrate 10, preferably sodalime or borosilicate glass; (2) 0.1-2.5 micron homogeneous powder of zinc sulfide crystals also containing about 0.1-1.0%, preferably about 0.4% by weight manganese and about 0.05% copper; (3) The crystal grains are immersed in an aqueous salt solution containing a salt selected from the group consisting of copper chloride and copper nitrate, whereby surface substitution of zinc is performed with copper, and copper sulfide is prepared. zinc sulfide coated with: producing manganese particles; (4) zinc sulfide coated with a dielectric binder, diluent and copper sulfide; a viscosity that allows the mixture of manganese particles to be applied to a transparent non-conductive substrate; mixing the dielectric binder with a dielectric binder in an amount sufficient to provide a dielectric binder having; (6) a mixture of zinc sulfide:manganese crystals coated with a dielectric binder, diluent and copper sulfide over a parallel transparent conductive anode 14 on a transparent non-conductive substrate 11; (7) Sulfide coated with dielectric binder, diluent and copper sulfide. A diluent is applied from the mixture of zinc:manganese particles to leave a series of zinc sulfide:manganese filaments 15 coated with a dielectric binder, diluent and copper sulfide: (8) Dielectric bonding Zinc sulfide coated with agent and copper sulfide:
A cathode 1 covering each striation of manganese particles is one cathode.
7; (9) In a dry air/snow environment in a dry box, the cathode 1
7. Electroluminescent strips of zinc sulfide:manganese particles coated with a dielectric binder and copper sulfide through the anode 14 and the zinc sulfide:manganese particles coated with a dielectric binder and copper sulfide. Applying a forming current sufficient to impart to the matrix of sense pixels 18; 1@ housing the panel 10 in a chamber (not shown) to which a vacuum can be applied and to which an inert gas can be introduced; (2) applying a partial vacuum to the chamber through a vacuum conduit (not shown) equipped with a shutoff valve; to reduce the pressure to an absolute pressure of mercury below 25 microns, preferably below 12 microns mercury to sublimate the ice in the panel and remove the sublimated ice from the chamber;
thereby removing water from the panel; 01 holding the partial vacuum until no more moisture is removed from the panel, typically for about 20-60 minutes; closing the shutoff valve in the QO vacuum conduit; Q51 an inert gas, preferably introduce dry helium or argon into the chamber; place a back cap 20 on the substrate 11 over the anode 14, phosphor element 15 and cathode 17 (see Figure 3);
permanently encasing the anode 14, phosphor element 15, and cathode 17 in an inert gas; testing the seal between the backcap 20 and the substrate 11 for leakage; and 118 ) Cathode 17 to emit phosphorescence under normal working conditions until the pixel response (the production of phosphorescence in response to the passage of current through the various pixels) is sufficiently uniform, typically for 1 to 2 hours. , pixel 18 and anode 1
The panel IO is manufactured by a process of aging by passing an electric current through 4.

Additional details regarding the generation of display panels can be found in Davi
No. 752.317, filed July 3, 1985 by D. Glaser.

Application of backcaps and testing for leakage are known techniques per se.

Bank cap 20 is preferably made of aluminum to avoid electrical contact between cathode 17 and anode 14. The back cap 20 is also made of glass. The back cap 20 is sealed over the anode 14, phosphor element 15 and cathode 17 to the substrate 11 using a low permeability cement, such as a low gas generating epoxy resin, i.e. a resin that does not generate large amounts of gas during its curing. Ru. A suitable cement is manufactured by Bacon Industries Inc.
f Watertown.

Mass, and Irvine, Califor
Unfilled Gyro grade adhesive (U
filled gyro-gradeadhes 1
ve) Bacon FA-1 engineered poxy resin adhesive.

Testing for large leaks can be done, for example, by submerging the panel with the included back cap in warm water and observing for air bubbles, while small leaks can be tested by placing the sealed panel in a vacuum chamber with a partial vacuum in the room. The presence of the inert gas contained therein and used to permanently encapsulate the anode 14, phosphorescent rostrum element X5 and cathode 17 can be detected by inspecting the chamber.

[Brief explanation of the drawing]

1 is a schematic perspective view of the electroluminescent matrix display panel according to the invention before application of the back cap; FIG. 2 is a detailed construction of the electroluminescent matrix display panel of FIG. 1; FIG. 3 is a view similar to FIG. 1 showing the application of a back cap. FIG.2

Claims (1)

[Claims] 1. In a phosphor for electroluminescent display, (a) phosphor particles with a particle size of 0.1 to 2.5 microns consisting of zinc sulfide containing 0.1 to 1.0% by weight of manganese; (b) (c) a dielectric binder; and (d) a phosphor comprising not more than 6 micrograms of water per gram (g) of total phosphor and binder. 2. A phosphor according to claim 1 having less than 3 micrograms of moisture per gram of total phosphor and binder. 3. A phosphor according to claim 1 having less than 2 micrograms of moisture per gram of total phosphor and binder. 4. The phosphorescent material according to any one of claims 1 to 3, wherein the phosphorescent material is dehydrated by freeze-drying. 5. Any one of claims 1 to 3, wherein the phosphorescent substance is dehydrated by simultaneously applying heat and a partial vacuum.
Phosphorescent substances listed in section. 6. (1) A transparent, flat, non-conductive substrate; (2) A number of mutually parallel transparent conductive anodes applied to one side of the transparent, non-conductive substrate; (3) A transparent, flat non-conductive substrate; on one side, overlying the transparent conductive anode, with a 15-40 micron thick phosphor layer consisting of a number of mutually parallel phosphor elements applied in an oblique direction to the transparent conductive anode; Each phosphor element consists of (a) 0.1-2.5 micron particle size phosphor particles consisting of zinc sulfide containing 0.1-1.0% manganese; (b) phosphor particles on the phosphor element; (c) a dielectric binder; and (d) no more than 6 micrograms of moisture per gram of total phosphor and binder; and (4) each applied to the phosphor element. An electroluminescent matrix display panel consisting of a large number of mutually parallel conductive cathodes. 7. Claim 6: Each phosphor element contains no more than 3 micrograms per gram of total phosphor and binder.
Display panel as described in section. 8. Claim 6: Each phosphor element contains no more than 2 micrograms per gram of total phosphor and binder.
Display panel as described in section. 9. 9. The display panel according to claim 6, wherein the phosphorescent material is dehydrated by freeze-drying. 10. 9. A display panel according to any one of claims 6 to 8, wherein the phosphor material is dehydrated by simultaneous application of heat and partial vacuum. 11. Claims further comprising a back cap sealed to the substrate over the anode, phosphor element and cathode with a low permeability cement to permanently enclose the anode, phosphor element and cathode in an inert gas. The display panel according to any one of items 6 to 8. 12. 12. The display panel of claim 11, wherein the cement is a low gas generating epoxy resin. 13. 12. The display panel according to claim 11, wherein the inert gas is dry helium. 14. 12. The display panel according to claim 11, wherein the inert gas is dry argon. 15. 12. A display panel according to claim 11, wherein the back cap is made of aluminum and is adapted to prevent electrical contact between the cathode and the anode. 16. 12. The display panel according to claim 11, wherein the back cap is made of glass. 17. (1) Applying a number of parallel transparent conductive anodes on one side of a transparent non-conductive substrate; (2) Homogeneous powder of zinc sulfide crystals containing 0.1-1.0% by weight of manganese; prepared to produce crystal grains with a particle size of 0.1 to 2.5 microns; (3) coating with copper sulfide by immersing the crystal grains in an aqueous solution of copper nitrate, thereby effecting surface displacement of zinc with copper; (4) producing a mixture of zinc sulfide:manganese particles coated with a dielectric binder, diluent and copper sulfide to a viscosity that allows the mixture to be applied to a transparent, non-conductive substrate; (5) mixing the dielectric binder with a dielectric binder in an amount sufficient to provide a dielectric binder having; (5) the mixture of dielectric binder and diluent with zinc sulfide coated with copper sulfide; manganese particles; (6) a mixture of zinc sulfide:manganese particles coated with a dielectric binder, a diluent and copper sulfide on a transparent non-conductive substrate, covering parallel transparent conductive anodes; (7) evaporating the diluent from a zinc sulfide:manganese sulfide mixture coated with a dielectric binder, diluent and copper sulfide; (8) Zinc sulfide coated with dielectric binder and copper sulfide: leaving a series of streaks with manganese particles;
Applying one cathode, the cathode, on each striation of manganese particles; (9) In a dry box, in a dry air atmosphere, the manganese particles and the anode: zinc sulfide coated with the cathode, dielectric binder and copper sulfide; (10) applying a sufficient forming current through the electroluminescent pixel matrix to provide a matrix of electroluminescent pixels with strips of zinc sulfide:manganese particles coated with an organic dielectric binder and copper sulfide; (11) Lower the temperature of the panel in the chamber to -10°C or lower to freeze the moisture in the panel into ice; (12) Install a shutoff valve in the chamber. Applying a partial vacuum through a vacuum conduit provided to reduce the pressure to less than 25 microns of mercury absolute to sublimate the ice in the panel and remove the sublimated ice from the chamber, thereby removing moisture from the panel. (13) maintain a partial vacuum until no more moisture is removed from the panel; (14) close the shutoff valve in the vacuum conduit; (15)
Introducing an inert gas into the chamber; (16) sealing the back cap over the anode, phosphor element, and cathode to the substrate with low permeability cement to permanently seal the anode, phosphor element, and cathode in the inert gas; (17) Test the seal between the backcap and the substrate for leakage; then (18) allow phosphorescence to occur under normal working conditions until the pixel response is sufficiently uniform. A method of manufacturing an electroluminescent matrix display panel comprising aging the panel by passing an electric current through the cathode, pixels and anode. 18. 18. The manufacturing method according to claim 17, wherein the temperature of the panel in the chamber is lowered to -30°C or lower. 19. 18. The method of claim 17, wherein the pressure is reduced to less than 12 microns of mercury. 20. 18. The manufacturing method according to claim 17, wherein the partial vacuum is maintained for approximately 20 to 60 minutes. 21. 18. The manufacturing method according to claim 17, wherein the inert gas is dry helium. 22. 18. The manufacturing method according to claim 17, wherein the inert gas is dry argon.