JPH0377640B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to the emission color of a thin film EL device, and in particular to multicolor EL emission by improving the structure of the light emitting layer.

<Prior art> AC-driven high-brightness light-emitting EL devices, in which both sides of a light-emitting layer doped with an active substance are coated with dielectric layers, have been put into practical use as thin-film EL devices used in light-emitting display parts of display devices, surface light sources, etc. ing. This thin-film EL element can emit high-intensity light by applying an alternating current electric field of several KHz, and has a long lifespan.

The emitted light color of a thin film EL device is determined by the type of active material doped to form a luminescent center in the emissive layer. For example, when the luminescent base material is ZnS and Mn is used as the active material doped into it, yellow-orange with _TbF3 , green with Mn
When TbF ₃ is doped to form a Mn-F composite center, the color is red; when TmF ₃ is used, the color is blue;
When PrF ₃ is used, white luminescent colors can be obtained. There are the following methods for obtaining multicolor EL emission from such a thin film EL element.

(1) A thin-film EL device is constructed by laminating light-emitting layers doped with different active substances, and each light-emitting layer emits EL light individually to obtain multicolor light emission.

(2) Obtain multicolor light emission by stacking thin film EL elements that exhibit different EL emission colors.

However, in the method (1) above, the light-emitting layer is driven by applying a current that has a DC component, so B-V
Lack of stability of properties. In addition, in method (3),
Although it is possible to drive multicolor light emission relatively stably, the thin film structure becomes a very multilayered structure, which causes manufacturing problems. In other words, in order to make a thin film multi-layered, it is necessary to obtain excellent adhesion between each layer and to alleviate the stress caused by the difference in thermal expansion between each layer, and these conditions can be met if the number of laminated layers increases. It becomes difficult.

<Object of the Invention> In view of the above-mentioned problems, the present invention provides a thin film EL that can easily obtain multicolor light emission by making full use of technical means for both the electrode structure and the structure of the light emitting layer.
The purpose is to provide an element.

<Example> FIG. 1 is a block diagram of a thin film EL element showing one example of the invention.

A transparent electrode 2 made of In ₂ O ₃ , SnO _{2 ,} etc. is placed on a glass substrate 1 , and Y ₂ O ₃ , Ta ₂ O ₅ , etc. are layered thereon.
A first dielectric layer 3 made of TiO ₂ , Al ₂ O ₃ , Si ₃ N, SiO ₂ or the like is formed in an overlapping manner by sputtering or electron beam evaporation. First dielectric layer 3
Three types of light-emitting regions 4a, 4b, and 4c are formed in sequence in parallel on the top, which are obtained by electron beam evaporation of sintered pellets made of ZnS with various active substances added thereto. At this time, the sintered pellets that serve as the targets for vapor deposition are pellets in which three types of active substances (Mn + TbF ₃ ), TbF ₃ , and TmF ₃ are doped into the ZnS base material at concentrations depending on the purpose. .
The light emitting regions 4a, 4b, 4c have a single layer structure, on which a second dielectric layer 5 made of the same material as the first dielectric layer 3 is laminated, and further on top of that, a second dielectric layer 5 made of the same material as the first dielectric layer 3 is laminated.
A back electrode 6 made of Al or the like is formed by vapor deposition.
The transparent electrode 2 and the back electrode 6 are connected to an AC power source,
The thin film EL element is driven. 3 types of light emitting areas 4
a, 4b, and 4c are determined by the EL emission colors corresponding to the three primary colors of light, and contain Mn and Mn as active substances.
The light emitting region 4a doped with TbF ₃ emits red, the light emitting region 4b doped with TbF ₃ green, and the light emitting region 4c doped with TmF ₃ emits blue light. These light emitting regions 4a, 4b, 4c are regularly arranged in a matrix on the first dielectric layer 3 by introducing electron beam evaporation technology, well-known etching technology, photolithography mask evaporation method, etc. A three-layer structure in which light emitting regions 4a, 4b, and 4c are sandwiched between dielectric layers 3 and 5 is fabricated. The transparent electrode 2 and the back electrode 6 each consist of a group of line electrodes formed into a band shape, and are arranged in directions orthogonal to each other. The transparent electrode 2 and the back electrode 6 constitute a matrix electrode structure, and the points at which they intersect become picture elements during display. The light emitting region 4a,
Each of 4b and 4c is arranged corresponding to each picture element, and one picture element corresponds to one light emitting area.
EL emission can be obtained. Therefore, by selecting each line electrode of the transparent electrode 2 and the back electrode 6 and applying a voltage, red, green, and blue EL light is selectively emitted for each picture element, thereby changing the color of the matrix. A display pattern is obtained. In addition, by controlling the applied voltage, the brightness of each EL emission color can be easily modulated, making it possible to perform a full-color display in which the three primary colors of EL emission with halftones are mixed and controlled.

Note that due to the characteristics of the light-emitting regions 4a, 4b, 4c, if there is a large difference in intensity in the luminance of the EL light emitting color at each pixel point, each light-emitting region 4a, 4b, 4c
Color display is performed after adjusting the brightness by adjusting the area of the pixel or by interposing a color filter layer in each picture element as necessary. In order to display full color, it is necessary to finely set the pixel arrangement pitch according to the resolution of the human eye, but the pixel arrangement pitch is determined by the size of the display screen and the corresponding display screen and normal human observation. Determined by the distance between locations.

In the above embodiment, the electrode structure may be a simple matrix structure or a multiple matrix structure with two or more layers.

<Effects of the Invention> As explained in detail above, the present invention provides a color light emitting display in response to selective voltage application to the electrodes by arranging a plurality of light emitting regions with different light emitting colors in parallel corresponding to the electrode structure. be able to. Furthermore, since the electrode structure is simple and the number of layers of thin films is small, it is suitable for mass production, and reliability as an element is ensured, making it possible to widely apply it to display devices.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a thin film EL device showing one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Glass substrate, 2... Transparent electrode, 3... First dielectric layer, 4a, 4b, 4c... Light emitting region,
5... Second dielectric layer, 6... Back electrode.

Claims (1)

[Scope of Claims] 1. A matrix electrode consisting of a transparent electrode 2 and a back electrode 6; a pair of dielectric layers 3 and 5 interposed between the transparent electrode 2 and the back electrode 6; a three-layer structure consisting of a light-emitting layer sandwiched between body layers 3 and 5, and the light-emitting layer includes a different light-emitting center at each intersection of the matrix electrodes and exhibits a different EL light emission color. A thin film EL device characterized by a single layer structure in which a plurality of light emitting regions 4a, 4b, 4c are arranged in regular alignment.