JPH0479192A - Construction for protecting electro-luminescence display panel - Google Patents

Abstract

PURPOSE:To maintain a small size and light weight and promote economical performance by providing a back face insulating film which covers, from the back face side the range of an EL display panel including the whole of an EL luminescent layer except for the end part for external connection of a transference electrode film and a back face electrode film, and a protective film made of metal which covers almost the whole of the back face insulating film from the back face side. CONSTITUTION:A protective construction is installed by being provided with a back face insulating film 20, which covers, from the back side the range of an EL display panel including the whole surface of an EL luminescent layer 5 except for the end part 2a for external connection of a transference electrode film 2 and a back face electrode film 6, and a protective film 30 made of metal, which covers almost the whole face insulating film 20 from the back side. In this case, the combination of the back face insulating film 20 and the protective film 30 made of metal can protect the EL luminescent layer 5 from the invasion of external air such as moisture or the like and from the contamination by a metal atom. Thus, an EL display panel can be satisfactorily economical and suitable to mass production without deteriorating such a small-sized and light-weight characteristic as the EL display panel has.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to electroluminescence (hereinafter referred to as EL).
The present invention relates to a protective structure for preventing outside air from entering a display panel.

[Conventional technology]

As is well known, EL display panels can be formed into a flat shape similar to liquid crystal display panels, and unlike them, they have the advantage of being luminescent.Recently, however, their display brightness has been further improved, and they have become suitable for displaying variable images. It is attracting attention as a display device such as ELL, which is smaller and lighter than a CRT device and has self-luminous properties.

In recent matrix-type EL display panels in which a large number of pixels are arranged in rows and columns to be suitable for such uses, the EL
The light emitting layer is constructed by laminating a light emitting film made of ZnS etc. and an insulating film, but in order to obtain high display brightness with as low a display voltage as possible, the thickness of the insulating film in this laminated structure must be reduced to 9 g.
The average value must be 0.54 or less. For this reason, if even a small amount of outside air, especially moisture, enters the display during use, the performance of the insulating film deteriorates and the display performance is likely to deteriorate, so it is necessary to provide sufficient protection against this. Hereinafter, an outline of an EL display panel and a conventional example of its protective structure will be explained with reference to FIGS. 3 and 4.

FIG. 3 is a perspective view of the main parts of the EL display panel 10. A transparent material such as glass is used as the insulating substrate 1, and a large number of transparent electrode films 2 made of, for example, ITO (indium tin oxide) are formed on the surface thereof in a striped pattern. The EL light emitting layer 5 laminated thereon is made up of, for example, a light emitting film 4 sandwiched between a pair of insulating films 3 as shown in the figure, where the insulating film 3 is a film of silicon nitride or the like, and the light emitting layer 5 is made of a material such as silicon nitride. 4 is Zn containing a small amount of transition metals such as Mn and rare earths such as Tb.
1119 of S et al. On this EL light emitting layer 5, a large number of back electrode films 6 made of aluminum or the like are arranged in a striped pattern in a direction perpendicular to the transparent electrode film 2. In addition,
One of the two insulating films 3 in the EL light emitting layer 5, particularly the insulating film 3 on the transparent electrode 12 side, may be omitted as appropriate.

In the EL display panel 10 with such a matrix structure, the EL light emitting layer 5 in the range corresponding to each intersection of the transparent electrode 1112 and the back electrode film 6 constitutes each pixel on the display, and the EL light emitted from each pixel is transmitted through a transparent insulator. It is taken out from the substrate 1 side toward the bottom of the figure.

In the example of the protective structure shown in FIG. 4, a sealing case 40 is attached to the back side of the EL display panel IO as described above.
(see publication). The case body 41 is a frame-shaped body, which is covered with a glass lid 42, the periphery of which is sealed with an adhesive 43, and bonded to the insulating substrate 1.
Apply a sealant 44 such as silicone oil to the case 40 from 2a.
After the sealing liquid 44 in the sealing case 40 is sealed, the sealing hole 42a is closed with a glass closing plate 45 and an adhesive 46.
Seal off. Note that the transparent electrode 1 to which the connection line 50 should be connected
For example, the twelve external connection ends 2a are led out to the outside of the sealing case 40 alternately on the left and right sides as shown in the figure, and the external connection ends of the back electrode film 6 are similarly led out in the front-rear direction in the figure.

[Invention tries to solve it! If) With the conventional protection structure described above, it is possible to almost completely block the intrusion of outside air, and by using a sealing liquid with high dielectric strength, it is also possible to improve the insulation properties of the insulating film of the back electrode film example. However, on the other hand, there are the following problems.

(1) Since the sealing case is attached, the thickness of the EL display panel becomes 2 to 3 times the original thickness, which reduces its characteristics as a flat panel, and the weight also increases by more than twice, reducing its characteristics as a lightweight panel. Ru.

(2) Since a considerable portion of the area of the display panel is consumed by the installation of the sealing case, the utilization efficiency of the panel area, expressed as the ratio of the effective display area to the total area of the panel, decreases.

(3) Since the lid needs to be made of alkali-free glass, the cost of materials for the sealed case is high.

(4) Before filling the sealing liquid, pretreatment such as heating and evacuation is required to remove moisture and gas within the sealing case, which requires considerable effort and cost. Furthermore, the work of adhering the main body of the sealing case to the display panel is quite cumbersome and time-consuming, and defects are likely to occur during mass production.

It is an object of the present invention to solve these conventional problems and provide a protective structure that is economical and suitable for mass production without diminishing the small size and light weight of the EL display panel.

[Means for Solving the Problem] According to the present invention, this object is to provide a transparent electrode film, an EL light emitting layer including a light emitting film and an insulating film, and a back electrode film on a transparent insulating substrate as described above. A back insulating film that covers the entire surface of the EL light-emitting layer from the back side of the EL display panel, excluding the external connection end portions of the transparent electrode film and the back electrode film, for an EL display panel formed by sequentially laminating the layers; This is achieved by providing a protective structure including a metal protective film that covers almost the entire surface of the back insulating film from the back side.

Note that the back insulating film in the above structure is silicon oxide,
Inorganic and organic insulating materials such as phosphorus silicate glass, silicon nitride, alumina, and talum oxide can also be used as appropriate, and metals for the protective film include single metals such as aluminum, chromium, tantalum, molybdenum, and titanium. These alloy materials can be used as appropriate, or this can be made into a metal film with a multilayer structure. moreover,
It is advantageous to cover this protective film with a resin material to protect it from damage, corrosion, etc.

(Function) The present invention has succeeded in solving the above-mentioned problems by paying attention to the airtightness of a metal thin film against outside air, especially moisture, and utilizing this in the protective film mentioned in the above-mentioned configuration.

As is well known, insulating films, especially silicon nitride films, are mainly used to block the intrusion of outside air in semiconductor devices, but according to the results of various experiments conducted by the inventor of the present invention, nitride films are used as far as EL display panels are concerned. Insulating films such as silicon films are unsuitable, that is, their barrier properties against outside air are insufficient, and this is probably because semiconductor technology protects semiconductor layers and gold 11:W! This is thought to be due to the fact that, in contrast, in an EL display panel, the insulating film and the like in the EL light emitting layer are protected.

According to the experimental results, metal films such as aluminum films have a very high effect of preventing outside air from entering into the insulating film in the EL light-emitting layer and the light-emitting film, which is insulating in terms of physical properties, even when the thickness is about 1. There are almost no microscopic racks or pinholes that are normally observed in insulating films such as membranes.

Like the second metal preservation IIW! is suitable for preventing outside air from entering the EL emitting layer, but since it is conductive, it must be insulated from the back electrode layer.
In addition to insulating the EL film from the back electrode film, it also serves to inactivate the surface of the EL light-emitting layer and prevent migration of metal atoms of the fIM to the EL light-emitting layer.

By combining this back insulating film and metal protective film,
Although the EL light emitting layer can be protected from intrusion of outside air such as moisture and contamination by metal atoms, in the present invention, these layers are further protected against intrusion of outside air from the external connection ends of the transparent electrode film and back electrode film. Excluding the external connection end of the electrode membrane,
A back insulating film is provided to cover the entire range of the EL display bubble including the entire surface of the EL light emitting layer from the back side, and then a protective film is provided to cover almost the entire surface.

With this structure of the present invention, deterioration of the light emitting characteristics due to invasion of outside air or contamination by metal atoms into the EL light emitting layer, including the lead-out portion of the external connection end of the electrode film, is almost completely prevented.

[Example] Hereinafter, an example of a protective structure for an EL display panel of the present invention will be described with reference to the drawings. FIGS. 1 and 2 are enlarged sectional views of essential parts of first and second embodiments of the present invention, respectively.

In FIG. 1, several hundred transparent electrode films 2 made of ITO or the like and having a thickness of about 0.2 m are arranged in a striped pattern as shown in FIG. 3 on a flat, transparent insulating substrate 1 made of glass or the like. In this embodiment as well, the external connection end portions 2a are alternately formed at both left and right ends of the insulating substrate l in the figure.

Although the EL light emitting layer 5 in this embodiment is also composed of a pair of insulating films 3 and a light emitting film 4 sandwiched between them, the insulating film 3 of the two examples of transparent electrode films can be omitted as appropriate. For example, silicon nitride is used for the insulating film 3, and the film is formed to a thickness of about 0.4 mm by sputtering or the like.
For example, the light emitting film 4 may contain 0.5 to 0.6 wt% Mn.
ZnS containing Zn is used, and the film is formed to a thickness of about 0.5 mm by the usual electron beam evaporation method.

After patterning the insulating layer 113 and the light emitting layer #4 by photoetching to form the EL light emitting layer 5 as shown in the figure, for example, aluminum is deposited on the entire surface to a thickness of about 0.5 mm by sputtering, and this is photo-etched. By etching, hundreds of back electrode films 6 are formed into a striped pattern arranged in a direction perpendicular to the transparent electrode 1l12, and this makes the E
The incorporation of the display portion into the L display panel 10 is completed. Note that the external connection end of this back electrode film 6 is transparent electrode #2.
As in the case of FIG.

In this example, alumina was deposited in a thickness of 0.5 t1 by sputtering or the like for the back insulating film 20 constituting the protective structure of the present invention.
After coating the entire surface to a film thickness of 0.5 to 1 mm thick, and then depositing aluminum for protection*30 on the entire surface by sputtering or the like to a thickness of 0.5 to 1 mm, first apply the desired aluminum for the protective film 30. Alumina for the back insulating film 20 is formed in the same pattern as the R1 film 30 in this example by chemical etching into a pattern, and then dry etching using this as a mask.

At this time, the back insulating film 20 and the protective film 30 expose only the peripheral part of the insulating substrate 1 where the external connection end 2a of the transparent electrode WA2 and the external connection end (not shown) of the back electrode film 6 are located, as shown in the figure. A pattern is formed to cover the entire remaining area including the entire surface of the EL light emitting layer 5 of the EL display panel 10 from the back surface side. It is best to completely seal the periphery of the pattern with the back insulation wI20 and the protection 11130 with a sealing film 35 coated with a thin layer of silicone resin and cured as shown in the figure. desirable.

With the above steps, the incorporation of the protective structure into the EL display panel IO is completed, and thereafter the external connection end portions 2a of the picture electrode films 2 and 6 can be connected to an external display drive circuit by means of the connection line 50 or the like.

It should be noted that it is advantageous to have a two-layer structure for the shield 11130 in this embodiment, which is a combination of aluminum and, for example, chromium, in order to reduce the probability of pinholes occurring in the metal thin film and to enhance the sealing effect against the outside air.

In this case, even with a film thickness of 0.5a or less, the rI retention film 30 can have a very high sealing effect.

However, if the film thickness of the protection 1I 130 is too thin, the sealing will easily break due to external damage, so it is better to protect the protection 130 and the back of the EL display panel 10 with a resin film before or after connecting the connection line 50. is also useful in preventing corrosion and rusting of the metal of the protective film 30.

In the second embodiment of the invention shown in FIG. 2, the protective structure is provided in two layers. The process is the same as the previous embodiment until the display part is incorporated on the insulating substrate 1, but a back insulating film 21 is formed on it.
Next, silicon oxide was deposited to a thickness of about 0.34 mm as a metal for the protective film 31, and tantalum was deposited to a thickness of about 0.2 mm as a metal for the protective film 31 by sputtering. is formed in the same pattern as in the previous example to form the first layer of protective structure.

Furthermore, in this embodiment, the back insulation 1l has the same configuration as described above.
A second protective structure made of N22 and a protective film 32 is formed in a slightly smaller pattern than the first layer as shown in the figure. In addition,
In this embodiment as well, it is desirable to provide a resin sealing film 35 so as to commonly cover the peripheries of the patterns of these two layers of protective structures.

In this second embodiment, the *a of both the back insulators 11121 and 22 and the protective films 31 and 32 is approximately half that of the first embodiment, so the total thickness of the two-layer protective structure is the same as that of the previous embodiment. Although it is said to be about the same level as the EL light emitting layer 5, although the double protection structure requires twice as much manufacturing time.
The effect of blocking outside air can be further enhanced. It is recognized that the tantalum used for the protectors 11231 and 32 of this second embodiment has a high effect of blocking outside air, especially moisture, even in the above-mentioned thin film.

The present invention is not limited to the embodiments described above, and the present invention can be implemented in various embodiments. For example, in addition to the above-mentioned alumina and silicon oxide, the back insulating film is made of inorganic materials such as silicon nitride, phosphosilicate glass, and tantalum oxide, and organic polymeric materials such as epoxy resin and phenol resin that can be patterned by photo process. available for use. Furthermore, it is possible to further improve the barrier performance against outside air by forming the back surface insulating film into a composite film such as a combination of silicon oxide and silicon nitride.

In addition to the above-mentioned aluminum and tantalum, metals for the protective film include single materials such as chromium, molybdenum, and titanium, as well as Al-5t, Al-5t-J+Mo-3i+Cr-
An alloy material such as 5i may be used, or if necessary, a composite membrane such as the above-mentioned combination of aluminum and chrome may be used to further enhance the barrier effect against outside air. It goes without saying that the methods for forming these metal films and patterning the protective film are not limited to those described in the examples, but should be adopted in a method most suitable for each material.

〔Effect of the invention〕

As described above, in the present invention, for an EL display panel in which a transparent electrode film, an EL light emitting layer including a light emitting film and an insulating film, and a back electrode film are sequentially laminated on an insulating substrate, the transparent electrode film and the back A back insulating film that covers an area of the EL display panel including the entire EL light emitting layer except for the external connection ends of the electrode film from the back side, and a protective film made of metal that covers almost the entire surface of this back insulating film from the back side. By providing a protective structure with
You can get the following effects.

(a) Focusing on the excellent airtightness of the metal thin film against outside air, especially moisture, this is maintained! By using I, EL
It is possible to almost completely prevent outside air from entering the light emitting layer. In addition, the back insulating film inactivates the surface of the EL light emitting layer and prevents the migration of metal atoms.
Decrease in luminance of light emission during the period of use of the display panel can be minimized.

(b) Since both the back insulating film and the protective film are one-order thin films, the thickness of the EL display panel is hardly increased due to the protective structure, and the features as a flat panel can be utilized as is. Furthermore, since there is almost no increase in weight, an extremely lightweight EL display panel can be provided.

(C) Since a sealing case like the conventional structure does not require space for its installation, the area utilization efficiency of the insulating substrate is improved, and it is possible to provide an EL display panel that is smaller than the conventional one.

(d) Since the cost of materials for the protective structure is significantly reduced compared to conventional sealed cases, the economic efficiency of the EL display panel can be improved.

(e) Since there is no need for labor to attach the sealing case and fill in the sealing liquid as in the past, the mass productivity of the EL display panel is improved.

The present invention having such features is expected to contribute to further popularization of EL display panels by improving their performance and economic efficiency.

[Brief explanation of the drawing]

1 to 3 relate to the present invention; FIG. 1 is an enlarged cross-sectional view of essential parts showing a first embodiment of the ML structure of an EL display panel according to the present invention, and FIG. 2 is a second embodiment thereof. FIG. 3 is a perspective view of the main part of the EL display panel. FIG. 4 is an enlarged sectional view of a main part of a protection structure for an EL display panel according to the prior art. In the figure, 1: insulating substrate, 2: transparent electrode film, 2a: external connection end of transparent electrode film, 3: insulating film of EL light emitting layer, light emitting film of IEL light emitting layer, 5: EL light emitting layer, 6° Back electrode film, 10:E
L display panel, 20-22: Back insulating film, 30-32:
It is an iJ-preserving film.

Claims (1)

[Claims] A protective structure for preventing outside air from entering an electroluminescent display panel, which is formed by sequentially laminating a transparent electrode film, an electroluminescent light emitting layer including a light emitting film and an insulating film, and a back electrode film on a transparent insulating substrate. ,
A back insulating film that covers the entire surface of the electroluminescent light emitting layer, excluding the external connection end of the transparent electrode film and the back electrode film, from the back side of the electroluminescent display panel, and a back insulating film that covers almost the entire surface of the back insulating film from the back side. A protective structure for an electroluminescent display panel comprising a protective film made of a covering metal.