JPS5858583A - Improved thin layer electroluminescent display device - 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 A typical thin film electroluminescent display consists of a substrate glass, a transparent conductor, a phosphor layer sandwiched between two insulating layers, and a phosphor layer sandwiched between two insulating layers. 4 has a multilayer structure consisting of a single opaque rear conductor made of aluminum.

When a KAC voltage is applied to these two conductors, light is generated in the phosphor, and the active ions are excited by electrons, resulting in one light emission.

For example, as used in aircraft instrument panels, etc.
A major issue with any type of display is how well the display is readable in extremely bright environments such as direct sunlight. Under these circumstances, the opaque back conductor with its high metallic reflectivity reflects more light than the electroluminescent elements emit, making the display difficult to read.

Many attempts have been made to provide fluorescent display devices that can be operated with high contrast ratios even in very bright environments without sacrificing the brightness of the emitted light.

One way to solve this problem is to incorporate a dark material into the glass layer or a dark dye into the dielectric layer with a fraction of the phosphor. A disadvantage of these methods is that the intensity of the emitted light is reduced as well as the reflected light.

It has been proposed and proposed to overlay an opaque porous layer on the viewer-facing surface of the substrate glass of this device, but this method is undesirable because it limits the viewing angle.

A proposal was made in US Pat. No. 5,560,784 to provide a light absorbing layer on the viewer side surface of the back conductor. Since the refractive index of this light-absorbing material is substantially the same as that of the phosphor layer, continuous movement occurs at the interface between the phosphor layer and the light-absorbing layer. , to minimize reflections on this interface. This light-absorbing layer is substantially transparent at the interface, but has a progressively increasing concentration of light-absorbing material toward the back layer.

The disadvantages of this method include the need for elaborate materials and complex controls, as well as the need for complex equipment for dispensing the light-absorbing material in decreasing concentrations into the thin film.

It has now been found that this problem of reflection, which occurs when a display is observed under extremely bright conditions, can be eliminated by using a material that has both an interference effect and an ability to absorb passing light as the black layer.

Figure 2 shows a substrate glass 1, a transparent conductor 2, and a transparent insulator 3.
, a phosphor layer 4, an insulating layer 5, and an aluminum conductor 6
This shows a normal display body consisting of.

This aluminum layer has a high metallic reflectivity, so it emits more light than an electroluminescent element when used in very bright environments, such as in direct sunlight. The efficiency of this display is hampered by the reflection towards the observer.

FIG. 3 shows a preferred embodiment of the invention.

1 layer 12 of a good drug deposited directly on the substrate glass 11
is a transparent and conductive film. This first layer is generally of a composition consisting of tin plating and indium oxide. A substrate glass having this coating is commercially available, for example, as Neaatron glass (trade name).

! The second layer 13 and the fourth layer 14 are insulating layers for preventing discharge breakdown. Materials such as yttrium oxide (Y2(Js)), aluminum oxide (AJL20.), r:IL methanalium 'f'Jlz05> or others are suitable for these layers.

The third layer 15 is a phosphor that serves as a light source.

Zn8:Mn (O-L/7-di), Ca8:Co
(green), 8r8: Co (blue), Zn
Preferred materials include, but are not limited to, 8: T+, Mn (vydo), and others.

The fifth layer 16 is a black layer and is a layer that improves contrast. This is a rigid film made of semiconducting, highly dispersive material. Since it has a favorable optical dispersion ability, favorable forced absorption occurs between the dielectric layer 14 and the back metal electrode layer 17- of this thin film electroluminescent display.

Lanthanum hexaboride (LaB6), oxidized OA (
Examples of preferred materials include, but are not limited to, Cr205), titanium oxide (TiO), vanadium oxide (20s), and boron carbide (BO2); these materials are fire-resistant ceramics due to their properties. She has a true female determination towards shorts and punks.

The final layer 17 is a back conductor, usually made of aluminum.

As shown in FIG.
The incoming light is reflected between the two interfaces formed by the black layer and is partially absorbed for every light that passes through the black layer, in other words, the black layer traps the incoming light. In addition, this material has an effective antireflection effect, so that significantly less light is reflected from this black layer.

The black layer 16 according to the present invention is formed on the back electrode 1 as shown in FIG.
It is preferable to provide it on the front surface of 7. However, in other positions, such as in place of the insulating layer 140 (FIG. 4),
It is also within the scope of the invention to provide a position K between the insulating layer 13 and the phosphor 15 (FIG. 5) or a position K as an alternative to the back electrode 17 (FIG. 6).

The thickness of each layer is not critical, but generally the skin df2#i on the glass layer is about 20OA to t000A4,
Preferably about 500A; phosphor layer 15 about 1.0OO
A to 10. up to C100A, preferably about 4.000
person; insulating layers 13 and 14 are each about 50 OA to 5 OA;
．． 000 At, preferably each about 2,0 OOA
The thickness of the aluminum electrode 17 ranges from about 200 to 1,000, preferably about 1,000, depending on the material selected.

Or about 250 people: Generally about 40 people for Ti0 layer
From OA 1. O[up to lOA, preferably about 500A;
■In the case of 2υ1 layer, it is generally about 300A to 1.00A.
0A', preferably about 3s OA; Cr2Os
For layers - about 300 people; for 804 layers - typically about 5OA to 500 people, preferably about 100 people. The small amount of residual reflected light appears green, magenta or gold, depending on the optical thickness of this black layer or the position of the T-wave peak in the visible spectrum. Therefore, it is possible to change the hue by changing the thickness of the black layer.

Experiments were conducted to illustrate the effectiveness of each layer material used as a black layer in an electroluminescent (EL) display device. When aluminum electrodes were used, this material was deposited between the electrodes and the insulating layer 14. This display body was tested using a Sylvania 8G-77 Sun Gun IfC and the results are shown in the following table: As is clear from the results in the above table, T i 04p La
When the electrical resistivity is extremely low as in the case of Bg,
This material can be used directly as a back electrode.

In either case, this black layer improves the contrast so that the gun can be placed 6 inches (15 mm) in front of the display (for daylight simulation) without obliterating the brightness of the display. (therefore 9 times brighter)
Good to be able to put it on.

By using this optical interference black layer, the reflectance from the interface between the black layer and the adjacent layer on the observer side as well as the interface between the black layer and the back metal conductor can be minimized (approximately 1%).
). In addition, the brightness of the emitted light is not sacrificed, with a brightness of 1,000 ft-L compared to about 100 ft-L for ordinary CRTK televisions (TVs).
-L or higher brightness is 1. Moreover, it had a lifespan of over 40,000 hours. - The product according to the present invention can be manufactured by any known or publicly available method. however.

Such thin-layer electroluminescent display devices are preferably manufactured by vacuum deposition, such as electron beam evaporation, whereby high resolution
n) can be manufactured.

The entire structure is typically sealed to prevent contamination from the outside world.

The display device according to the invention is suitable for example for numerical displays or vertical scale displays for aircraft instrument panels, computer terminals, word glossers and others.

Circular dial display, luminous crosshair,! It is suitable for use in electroluminescent panels such as trix displays and other types of information display boards.

[Brief explanation of the drawing]

FIG. 1 is a route diagram showing the state in which input light passes between an insulating layer and a back conductor in an electroluminescent display device. FIG. 2 is an enlarged sectional view showing a conventional electroluminescent display device. Figure wX3 is an enlarged sectional view showing a preferred embodiment of the present invention. FIG. 4 is an enlarged sectional view showing another embodiment of the invention. FIG. 5 is an enlarged sectional view showing another embodiment of the invention. FIG. 6 is an enlarged sectional view showing another embodiment of the invention.

Claims (1)

[Claims] (1) Glass observation surface, transparent conductor, two insulating layers K
・-In a thin-layer electroluminescent display device x consisting of a sandwiched phosphor layer and an opaque back conductor, an improvement is made by inserting a material that interferes with the input light to minimize the reflection on the llN#J surface. Kai-Arashi has been designed to give you nine contrasts. Q) Claim 1, characterized in that the optical interference layer is a hard film made of a highly dispersive semiconducting material.
Devices listed in section. 3. Device according to claim 1, characterized in that the optical interference material is selected from the group consisting of lanthanum hexafluoride, chromium oxide, titanium oxide, panadicum oxide and boron carbide. (4) The device according to claim 1, wherein the optical interference layer is provided between the back conductor and the insulating layer. 5. Device according to claim 1, characterized in that the optical interference layer is provided between the phosphor layer and the insulating layer adjacent to the transparent conductor. 2. Device according to claim 1, characterized in that this optical interference layer is provided between the phosphor layer and the opaque conductor instead of an insulating layer. (7) A device according to claim 1, characterized in that this optical interference layer is used in place of an opaque back conductor.