JPH02168593A - Large screen multicolor 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 [Field of Industrial Application] The present invention relates to a large screen multicolor display device and a multicolor thin film EL element constituting the same.

[Prior Art] Thin film EL devices utilize the light emission phenomenon that occurs when a strong electric field is applied to a phosphor, and are being applied as large-screen flat panel displays with excellent visibility.

A typical structure of a thin film EL cable is, for example, as shown in FIG. It is something.

As shown in Figure 4, a conventional stacked multicolor thin film EL device has a structure in which multiple light emitting layers with different emission wavelength characteristics, an insulating layer and an electrode sandwiching the layers are stacked, and the light emitted from each light emitting layer is are mixed three-dimensionally to emit multicolor light.

The material for the transparent electrode is ITO (Indium Oxide), which is a mixture of tin oxide and indium oxide.
de) is commonly used. However, ITO has poor heat resistance, and when an alkaline earth chalcogenide is used as a light emitting layer, it is necessary to heat the substrate to a high temperature, which may result in increased resistance or decomposition of ITO. For this reason, attempts have been made to use zinc oxide, which is said to have better heat resistance than ITO, but nothing with excellent long-term reliability has been obtained. The problem of high resistance of transparent electrodes becomes more pronounced as the electrodes become longer, and becomes a particularly serious problem in large-screen displays.

Laminated multicolor thin film EL requires multiple layers of transparent electrodes, and the thermal history increases each time a light-emitting layer and an insulating layer are laminated, so the transparent electrodes are required to have high thermal stability. Ru.

Conventionally, light-emitting diodes (L
ED) as pixels have been put into practical use.

However, display devices using LEDs as pixels have the disadvantage that manufacturing costs are high because the elements are relatively expensive and positioning of the elements is difficult. Furthermore, since blue light emission has not been put to practical use, it is difficult to achieve full color. In addition, there is also a problem in terms of cost when constructing a large-screen multicolor display device using a plasma display, a liquid crystal display element, or the like as a pixel. On the other hand, it is possible to use thin-film electroluminescent elements (hereinafter abbreviated as thin-film EL elements) as pixels in large-screen multicolor display devices, but an element with a structure suitable for such a purpose had not been considered in the past. .

[Problems to be Solved by the Invention] The present invention solves the above-mentioned problems in a large-screen multicolor display device and a multicolor thin film EL string constituting it, and provides a large-screen multicolor display device capable of high-definition, full-color display. It is an object of the present invention to provide a display device and a highly reliable multicolor thin film EL element that can easily and accurately constitute a large screen multicolor display device at low cost.

[Means for Solving the Problems] The structure of the present invention to achieve the above object is as follows: (1) A large pixel characterized in that a pixel is formed by a light scattering material provided in an edge emitting part of a thin film electroluminescent element. Screen multicolor display device.

(2) A long thin film obtained by scribing a thin film electroluminescent device in which a metal electrode, an insulating layer, and a light-emitting layer are sequentially laminated on a glass substrate into a long length, providing a light scattering material on the end face, and further providing the above-mentioned light scattering material. A large-screen multicolor display device characterized by a combination of multiple electroluminescent elements.

(3) Layering multiple light-emitting layers with different emission wavelength characteristics, providing an insulating layer and a metal electrode between each light-emitting layer, and adding a light scattering material to the light-emitting layer to mix light from each light-emitting layer by scattering. Claim (1) characterized in that it is provided on the end face.
) or a multicolor thin film electroluminescent element for a large screen multicolor display device according to claim (2).

An example of the structure of the thin film EL element of the present invention will be explained with reference to the drawings. In Figure 1, 1 is a glass substrate, 2.6 and 1
0 is a metal electrode, 3, 5, 7, and 9 are insulating layers, and 4 and 8 are light emitting layers. Reference numeral 11 denotes a scattering material made of a substance that scatters light, and is provided in a portion after parts of the light emitting layers 4 and 8, the insulating layers 5, 7 and 9, and the metal electrodes 6 and 10 are removed by etching. . When a high voltage is applied between metal electrodes 2-6 and 610, electroluminescence light emission occurs due to a strong electric field within the light emitting layer. The light is reflected by the metal electrode and is emitted only from the end surfaces of the light emitting layers 4 and 8 as shown by the arrows without leaking upward or downward. Scatter material 11
The light emitted to the surface is diffusely reflected, but since the light directed downward is reflected by the metal electrode 2 on the lower surface, the light is emitted only to the scattering material -1- surface. That is, the light generated in the light emitting layers 4 and 8 can be mixed by the scattering material 11 and extracted in four directions perpendicularly upward to the substrate.

In the above configuration, in order to extract light above the substrate,
The substrate does not necessarily have to be transparent, and a transparent substrate such as a ceramic substrate can be used instead of a glass substrate.

As the metal electrodes 2.6 and 10, aluminum, silver, etc. can be used. In addition, the materials for the insulating layers 3.5.7 and 9 include S io2, Ta205, Y203
oxides such as, nitrides such as BN, AIN, Si3N4, etc., gold films thereof, fluorides such as CaF2, MgF2, or perovskite type ferroelectric materials such as 5rTi03 and PbTi0a can be used. As a light emitting layer,
ZnS to which Mn or Tb is added or a chalcogenide of an alkaline earth element to which a rare earth element such as Ce or Eu is added is used. Thin film E laminated using the above materials
In order to form the scattering material 11 for light extraction in the L element, a part of the element is removed by photolithography. Next, a light scattering material such as epoxy resin is formed to complete the display device.

Next, a large-screen multicolor display device of the present invention constructed from thin film EL elements having a structure different from that described above will be explained with reference to the drawings.

FIG. 5 shows how a large number of multicolor thin film EL elements constituting pixels of a large screen multicolor display device are formed on a glass substrate. 51 is a glass substrate, 52 is a stacked multicolor thin film EL device in which a metal electrode, an insulating layer, and a light emitting layer having different emission wavelength characteristics are sequentially stacked, and 53, 54, and 55 are metal electrodes.

Next, move the glass substrate on which the multicolored thin film EL cords are formed to the arrow A
and the dotted line portions indicated by B to obtain a long edge-emitting multicolor thin film EL device. FIG. 6 shows a thin film EL cord obtained by scribing, viewed from above. In order to provide an extraction electrode, the metal electrode is patterned as shown in the figure.

Figure 7 shows the thin film EL cords obtained by scribing with arrow A.
2 is a cross-sectional view of the element viewed from the end face direction shown in FIG. 56, 58, 59 and 61 are insulating layers, 57 is a first light emitting layer, and 60 is a second light emitting layer. In this thin film EL element, when a voltage is applied between the metal electrodes 53 and 54 or between the metal electrodes 54 and 55, strong light is emitted from the end face of the light emitting layer 57 or 60. The luminance of light emitted from the end face is approximately 100 times higher than that of surface light emission. The light is emitted from a narrow region with a width of about 1 μm, and the intensity is very strong, so it is not suitable for application as a pixel in a display device as it is. That is, in order to construct an element having an appropriate size and brightness as a pixel of a large screen display device, it is necessary to disperse light to some extent. FIG. 8 shows how a light scattering material 76 is formed on the end face portion of the element as a pixel for this purpose. 1st and 2nd
Light having different emission wavelength characteristics emitted from the end faces of the light-emitting layer is mixed within the light scattering material, and the mixed light is emitted from the surface of the light scattering material. The light scattering material not only makes the brightness within the pixel uniform, but also has the effect of protecting the thin film EL string.

A large screen multicolor display device is completed by combining a large number of arrayed edge-emitting layer thin film EL elements produced as described above. Positioning of the elements during assembly is relatively easy and accurate since many pixels are already lined up in a straight line.

In the above configuration, since light is extracted from the end face of the element, the substrate does not necessarily have to be transparent, and an opaque substrate such as a ceramic substrate can be used instead of a glass substrate. . As a metal electrode,
Use AI. As the insulating layer, SiO2, Ta205,
Oxides such as Y2O3, BN.

AIN S 5i3NiO, PbTi0
A perovskite-type ferroelectric material such as Ko can be used. The light-emitting layer is made of Zn doped with Mn or Tb.
A chalcogenide of an alkaline earth element to which S s or a rare earth element such as Ce or Eu is added is used. The multicolored thin film EL cord laminated using the above-mentioned materials is scribed with a diamond scriber or the like, and a light scattering material made of epoxy resin or the like is formed on the end face of the light emitting layer by molding.

[Example] The present invention will be explained in more detail with reference to Examples below.

Example 1 In the device having the configuration shown in FIG. 1, aluminium-non-licade glass was used as the glass substrate 1.

Metal electrodes 2.6 and 10 are aluminum, insulating layers 3 and 7 are AIN, insulating layers 5 and 9 are AIN and 5i02
, the light-emitting layer 4 is CaS doped with Eu, and the light-emitting layer 8 is
were formed from Ce-doped SrS. Araldite (main material: XN1233-4A1 hardening material: XN
1233-4B, made by Ciba Geigy Japan) with light scattering material (
A dispersion of XN 1234 (manufactured by the same company) was used.

In order to reflect the light by the metal electrode 2 of the light extraction part,
Furthermore, since it is necessary to separate the light-emitting layer for each element to prevent light from leaking to adjacent elements, a lift-off method was used in the lithography process. In this way, a circular opening having a diameter of about 111ffl was provided as a light extraction section, and a white epoxy resin was further formed as a scattering material in this circular opening. At this time, the epoxy resin also serves as a protective material for the element. According to the device of this example, the light emitted from the end face of each light emitting layer was scattered by the epoxy resin scattering material, and mixed light appeared on the upper surface of the substrate. Further, in this example, no increase in the resistance of the electrode after the device was formed, which was observed in devices using transparent electrodes, was observed. Note that this embodiment does not have a configuration in which light is emitted through the glass substrate, so it is clear that an opaque ceramic substrate may be used instead of the transparent glass substrate.

Embodiment 2 FIG. 2 shows another embodiment of the present invention, which is similar to the above embodiment and 11.
At 7″Q, aluminum metal electrodes 13.17.21 and 25, AIN insulation layer 14.18 are placed on the glass substrate 12.
and 22, insulating layers 16 made of a laminated film of AIN and SiO2, 20 and 24, a light emitting layer 14 made of CaS doped with Eu, a light emitting layer 19 made of ZnS doped with Tb, and a light emitting layer 19 made of SrS doped with Ce. A light emitting layer 23 was formed. The light-emitting layer was separated for each element to prevent light from leaking to adjacent elements. The diameter of the light extraction part is approximately 1.
A circular opening of m was provided, and the scattering material 26 was formed using the same white epoxy resin as that used in Example 1.

Example 3 In the device formed as shown in FIG. 7, aluminosilicate glass was used as the glass substrate 51. Metal electrode 53.54
and 55 is aluminum, and insulating layers 56 and 59 are A
The IN and insulating layers 58 and 61 were formed of laminated films of AIN and 5i02, the light emitting layer 57 was formed of Eu-doped CaSs, and the light-emitting layer 60 was formed of Ce-doped SrS.

The same epoxy resin used in Example 1 was used. In addition, to prevent crosstalk between pixels,
The thin film EL cell was separated into pixels using a photolithography process.

In this example, the thin film EL element is formed only on one side of the glass substrate, but it is also possible to form the thin film EL element on the back side of the substrate in exactly the same way as on the front side, thereby doubling the luminance of the pixel. It is possible to do so.

Embodiment 4 FIG. 9 shows another embodiment of the present invention. Similar to the above embodiment, aluminum metal electrodes 84, 88, 92, 93 and 97 and an AIN insulating layer 8 are provided on the front and back sides of a glass substrate 83.
5.89 and 94, insulating layers made of laminated films of AIN and 5iOz87.91 and 96, CaS doped with Eu
A light emitting layer 86 made of the above-mentioned material, a light emitting layer 90 made of ZnS doped with Tb, and a light emitting layer 95 made of SrS doped with Ce were formed.

The device was separated into individual pixels to prevent crosstalk. Next, scribing was performed in the same manner as in Example 3 to form an epoxy resin as a scattering material on the end face of the light emitting layer.

[Effects of the Invention] As described above, according to the present invention, since a transparent electrode is not used, a multicolor thin film EL cord having excellent long-term reliability without increasing the resistance of the electrode can be obtained.

Further, by using the EL hydrogen elements, it is possible to easily provide a large-screen multicolor display device capable of high-definition, full-color display at low cost.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a sectional view of another embodiment of the present invention, and FIG. 3 is a conventional thin film EL cord.
The figure shows a cross-sectional view of a conventional multicolored thin film EL cord. FIG. 5 is a perspective view of a multicolor thin film EL device formed on a glass substrate, FIG. 6 is a top view of the multicolor thin film EL device,
FIG. 7 is a cross-sectional view of a multicolor thin film EL device, and FIG. 8 is a diagram showing a part of the multicolor thin film EL device when a light scattering layer is formed on the end face and assembled as a large screen multicolor display device. FIG. 9 is a diagram showing a cross-sectional view of the multicolor thin film EL element used in Example 2. 1.12,27,33,51,71.83...Glass substrate, 52...Laminated multicolor thin film EL element, 2, mouth, to, 13,17,21,25,32.42,
53.54゜55.73,74,75,84,88,9
2,93.97...Metal electrode, 3.5,7,9,14
．． 1G, 18, 20, 22, 24, 29°31.35,
37, 39.41, 56, 58, 59, 81, 85゜1
17.119,9L94.98...Insulating layer, 4.8,
15, 19, 23, 30.3B, 40.57.60.8
G. 90.95...Light emitting layer, 11.26.76...Light scattering material, 28.34.38...Transparent electrode. Figure 1 Figure 3 Figure 2'4 Figure 2

Claims (3)

[Claims] (1) A large-screen multicolor display device characterized in that pixels are formed from a light scattering material provided in the edge-emitting portion of a thin-film electroluminescent element. (2) A long thin film obtained by scribing a thin film electroluminescent element in which a metal electrode, an insulating layer, and a light-emitting layer are sequentially laminated on a glass substrate into a long length, providing a light scattering material on the end face, and further providing the above-mentioned light scattering material. A large-screen multicolor display device characterized by a combination of multiple electroluminescent elements. (3) Layering multiple light-emitting layers with different emission wavelength characteristics, providing an insulating layer and metal electrodes between each light-emitting layer, and adding a light-scattering material to the light-emitting layer to mix light from each light-emitting layer by scattering. A claim characterized in that it is provided on an end face (
1) or a multicolor thin film electroluminescent element for a large screen multicolor display device according to claim 1).