JPH0351080B2 - - Google Patents

Description

[Detailed Description of the Invention] A. Field of Industrial Application The present invention provides EL (Electro
This invention relates to a structure for sealing the injection hole of a fluid for protecting thin-film EL elements, which is an effective technique for EL display panels using thin-film EL elements that emit light (luminescence).

B. Prior Art Conventionally, for AC-operated thin-film EL devices, a high electric field (about 10 ⁶ V/cm) was regularly applied to the light-emitting layer to improve dielectric strength, luminous efficiency, operational stability, etc. ~2.0Wt% Mn (or Cn,
A three-layer structure ZnS:Mn (or ZnSe:Mn) in which a semiconductor light-emitting layer such as ZnS, ZnSe, etc. doped with Al, Br _, etc. is sandwiched with a dielectric thin film such as Y ₂ O ₃ , TiO 2, etc.
EL devices have been developed, and improvements in various light-emitting characteristics have been confirmed. This thin film EL element emits high-intensity light when an alternating current electric field of several KHz is applied, and has a long lifespan.

As an example of a thin film EL device, the basic structure of a ZnS:Mn thin film EL device is shown in FIG.

The structure of the thin film EL element will be explained in detail based on FIG. 1. 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 , etc.
A first dielectric layer 3 made of TiO ₂ , Al ₂ O ₃ , Si ₃ N ₄ , SiO ₂ or the like is formed in an overlapping manner by sputtering or electron beam evaporation. A ZnS light emitting layer 4 is formed on the first dielectric layer 3 by electron beam evaporation of ZnS:Mn sintered pellets. At this time, the ZnS:Mn sintered pellets used for deposition are pellets in which the concentration of Mn, which is an active substance, is set to suit the purpose. A second dielectric layer 5 made of the same material as the first dielectric layer 3 is laminated on the ZnS light emitting layer 4, and a back electrode 6 made of A1 or the like is further deposited thereon. As shown in FIG. 2, the transparent electrode 2 and the back electrode 6 are formed into a strip shape, and a matrix electrode structure is adopted in which a plurality of electrodes are arranged perpendicularly to each other.
The position where and the back electrode 6 intersect in plan view corresponds to one pixel of the panel. The transparent electrode 2 and the back electrode 6 are connected to an AC power source 7, and the thin film EL element is driven.

When an AC voltage is applied between the electrodes 2 and 6, the above AC voltage is induced between the dielectric layers 3 and 5 on both sides of the ZnS luminescent layer 4, and therefore the electric field generated within the ZnS luminescent layer 4 Therefore, electrons that are excited and accelerated by the conductor and have obtained sufficient energy can directly
The Mn luminescent center is excited, and when the excited Mn luminescent center returns to the ground state, it emits yellow light. In other words, electrons accelerated by a high electric field reach the ZnS light emitting layer 4.
When the electron of the Mn atom that enters the Zn site, which is the luminescent center of the inside, is excited and falls to the ground state, approximately
It emits strong light in a wide wavelength range with a peak of 5850 Å.

The thin film EL element having the structure described above can be used as a flat thin display device that takes advantage of the space factor to display characters, symbols, still images, moving images, etc. It can be used as a means of displaying images, etc., and is very effective.

However, the dielectric layer of a thin-film EL element contains many pinholes and microcracks generated during the manufacturing process, and moisture, etc. enters the ZnS light-emitting layer 4 through these defects, causing heat generation due to EL emission loss and interlayer This may lead to peeling, deterioration of device characteristics, etc.

In order to solve the above problem, as shown in Figure 3, we have investigated the expansion of the microscopic thermal damage area that occurs due to the breakdown caused by imperfections peculiar to thin film EL elements, such as pinholes, during energization. A thin-film EL panel 8 is known that prevents and fixes moisture in an atmospheric environment, has a heat dissipation effect, and is also effective against vibration and deflection.

This thin film EL panel 8 will be explained based on FIG. 3. Reference numeral 1 is the glass substrate shown in FIG. Element 9 is configured. A dish-shaped rear glass plate 10 is superimposed on the glass substrate 1 so as to house the thin film EL element 9, and the thin film EL element 9 is built into the internal gap thereof.
The joint between the glass substrate 1 and the rear glass plate 10 is sealed with an adhesive such as photocurable resin (Photobond). That is, the glass substrate 1 and the back glass plate 10
constitutes an envelope 11 for the thin film EL element 9.
A thin film EL element 9 is housed in the envelope 11, and an insulating protective fluid 12 for protecting the thin film EL element 9, such as silicone oil or vacuum grease, is filled and sealed. The requirements for the insulating protective fluid 12 include permeability into pinholes, high dielectric strength, excellent heat resistance and moisture resistance, and thin film EL.
It is desirable that it is a fluid substance that does not react with the element constituent films and has a low vapor pressure and coefficient of thermal expansion, but in particular it must be able to penetrate pinholes, have a somewhat high dielectric strength voltage, and not react with the thin film EL element constituent films. It takes.

Further, one end of the lead terminal portions of the transparent electrode 2 and the back electrode 6 of the thin film EL element 9 is extended onto the glass substrate 1 outside the envelope 11 via the joint between the glass substrate 1 and the back glass plate 10. , and are electrically connected to a drive control circuit (not shown).

In the thin film EL panel 8 having the above structure, the insulating protective fluid 12 is injected and sealed through the injection hole 13 provided in the rear glass plate 10, and the process procedure is shown below. (Tokuko Showa 57
-47559, JP-A-57-191991) First, as shown in Fig. 4, soda glass with a thickness of 3 mm is used as the back glass plate 10, and the housing part of the EL element structure is sand etched to a depth of about 1 mm. Concave molded. An injection hole 13 for fluid injection is formed at one corner of the concave molding area, and a hollow injection pipe 14 is inserted and fixed therein. The injection pipe 14 is made of metal and is fixed to the injection hole 13 with adhesive.

Fluid injection and sealing are performed via the operations shown in Figures 5a, b and 6a, b, c.

An envelope 11 composed of a glass substrate 1 and a rear glass plate 10 and a fluid storage tank 15 are placed in a vacuum chamber 16 as shown in FIG. 5a. At this time, the tip of the injection pipe 14 of the envelope 11 is separated from the injection fluid in the fluid storage tank 15. In this state, the pressure inside the vacuum chamber 16 is reduced, and the injected fluid and the gas from the thin film EL element 9 are vented. Next, the fluid storage tank 15 is raised while maintaining the vacuum, and the injection pipe 14 is moved up as shown in FIG. 5b.
Insert the tip into the injection fluid. After this, the vacuum chamber 16 is returned to atmospheric pressure, thereby causing the envelope 1
The injection fluid in the fluid storage tank 15 flows into the injection pipe 1 through the injection pipe 14.

At this time, the temperature inside the vacuum chamber 16 is raised as necessary,
It is also possible to increase the fluidity of the injection fluid.

When the injection operation of the injection fluid is completed, in the state shown in FIG. 5b, the portion of the injection pipe 14 near the junction of the envelope 11 is crimped as shown in FIG. 6a to perform temporary sealing. After that, the injection pipe 14 of the temporary sealing part is cut as shown in FIG. 6b, and the cut part is filled with epoxy resin 1.
7 to strengthen the seal as shown in FIG. 6c.

Next, a glass cap 18 having a concave portion in which a sealing portion of the injection pipe 14 can be placed is attached to the injection pipe 1.
4 is covered with adhesive on the rear glass plate 10 of the sealing portion, forming a double sealing structure against the injection fluid as shown in FIG. As the adhesive for bonding the glass cap 18 to the rear glass plate 10, a photocurable adhesive (Photobond) or the like is used. With the above steps, the enclosing operation process is completed.

However, according to the conventional injection sealing structure for the insulating protective fluid 12 in the thin film EL panel 8,
Since the fluid injection pipe 14 is adhesively fixed to the injection hole 13, it is necessary to adhesively fix a new injection pipe 14 each time the above-mentioned sealing operation process is repeated, which makes the process complicated.

Further, since the protective fluid 12 sealed in the envelope 11 is in a sealed state, when the panel temperature rises during a thermal cycle test or during operation, the protective fluid 12 thermally expands and the injection pipe 14 is The protective fluid 12 may leak from the temporary seal. This leakage protection fluid is stored in the recessed part of the glass cap 18, but leakage of the protection fluid 12 from the temporary sealing part of the injection pipe 14 is not desirable in terms of moisture resistance.
Conversely, when the thermally expanded protective fluid 12 contracts, the leaked protective fluid 12 is difficult to return to its original state, and the glass cap 1
There is also the disadvantage of inhaling gas within 8.

C. Object of the Invention The object of the present invention is to provide an injection method used for sealing a protective fluid in a thin-film EL panel in which a thin-film EL element and its insulating protective fluid are housed in an envelope consisting of a translucent front substrate and a back plate. This makes it possible to use the pipe repeatedly, and by elastically displacing the sealing part of the injection hole, it absorbs the volume increase pressure caused by thermal expansion of the protective fluid and prevents leakage of the protective fluid from the sealing part. That's true.

D. Structure of the Invention The present invention provides a thin-film EL panel in which a thin-film EL element and an insulating protective fluid for the thin-film EL element are housed in an envelope consisting of a translucent front substrate and a back plate. A packing material having a hole smaller in diameter than the injection hole is concentrically arranged and adhesively fixed to the provided injection hole for the protective fluid, and after the protective fluid is injected, the hole in the packing material is sealed with a deformable thin plate. and the thin plate is covered and sealed with a cap with a recess.

E. Examples Examples of the thin film EL panel according to the present invention will be described in accordance with the manufacturing process order of its protective fluid injection sealing structure. First, as the rear glass plate 10 of the thin-film EL panel, a soda glass plate of a predetermined thickness is heated and pressure molded as shown in FIG. be done. An injection hole 13 for fluid injection is formed at one corner of the concave molding area.

Next, as shown in FIG. 9, a packing material 19 having a hole is arranged concentrically with the injection hole 13 and fixed by adhesive. The hole diameter of the packing material 19 is formed to be smaller than the injection hole 13. In addition, the first packing material 19 is
It may be formed into a shape that covers the inner circumferential surface of the injection hole 13 as shown in FIG.

Then, as shown in FIG. 11, an external injection pipe 20 for fluid injection is inserted into the hole of the packing material 19.
The external injection pipe 20 is not adhesively fixed to the injection hole 13,
When the fluid injection is completed, the fluid is extracted from the injection hole 13. Therefore, the external injection pipe 20 can be used repeatedly, and at the same time, the packing material 19 prevents the injection of fluid.
Also, fluid leakage when the external injection pipe 20 is removed is prevented.

Rear glass plate 10 with external injection tube 20 inserted
If the envelope 11 for housing the thin film EL element 9 is configured by the glass substrate 1, then as in the conventional case, FIG. 12a,
As shown in b, an insulating protective fluid 1 is placed inside the envelope 11.
2 is injected. That is, first, the envelope 11 and the fluid storage tank 21 are placed in a vacuum tank 22 as shown in FIG. 12a. At this time, the external injection pipe 20 of the envelope 11
The tip is separated from the injection fluid in the fluid storage tank 21. In this state, the pressure inside the vacuum chamber 22 is reduced, and the injected fluid and the gas from the thin film EL element 9 are vented. Next, the fluid storage tank 21 is raised while maintaining the vacuum, and the first
The tip of the external injection tube 20 is inserted into the injection fluid as shown in Figure 2b. After this, N ₂ is added to the vacuum chamber 22.
Gas is introduced to normal pressure, thereby causing the envelope 11 to
The injected fluid in the fluid storage tank 21 is transferred to the external injection pipe 2.
Injected via 0.

When the injection operation of the injection fluid is completed, the envelope injection tube 20 is removed from the envelope 11. At this time, after the external injection tube 20 is removed and fluid is replenished so that no gas remains in the envelope 11 after sealing the packing material 19, the fluid surface is level with the surface of the packing material 19 as shown in FIG. Avoid further decline. This step is preferably carried out in a _N2 gas atmosphere.

Then, as shown in FIG.
Seal it inside 1. The thin plate 23 must be stretchable so that it can deform according to the expansion and contraction of the protective fluid 12, and its shape can be a thin flat plate made of rubber as shown in Figures 15a and 15b, or a thin flat plate made of rubber as shown in Figure 16a. ,b
As shown in the figure, it is a flat metal plate with pleats. That is, since the thin plate 23 is expandable and contractible, the fluid sealing portion is prevented from being damaged during thermal expansion of the fluid, and at the same time, fluid leakage is also prevented.

Furthermore, as shown in FIG. 17, a cap 24 having a concave portion is placed on the rear glass plate 10 of the sealing portion of the injection hole 13 via an adhesive to form a double sealing structure against the injection fluid. As shown in FIG. 18, the cap 24 has a two-stage recessed portion, and a first sealing surface 24a and a second sealing surface 24b are formed. That is, cap 2
4, the first sealing surface 24a presses and seals the thin plate 23 and the packing material 19, and the second sealing surface 24b
is adhered to the rear glass plate 10 for sealing. Here, if a protrusion 24c is provided on the first sealing surface 24a as shown in FIG. 19, the pressure contact between the thin plate 23 becomes stronger and the sealing becomes more reliable. Also, the height of the first sealing surface 24a from the top of the rear glass plate 10 is determined by the height of the thin plate 23.
It is also possible to strengthen the pressure contact of the thin plate 23 by making the thickness smaller than that of the packing material 19. Therefore, the height of the first sealing surface 24a can be allowed within a predetermined range. and second sealing surface 24b
A photocurable resin or the like is used for adhesion.

A thin film EL panel is created through the above-mentioned encapsulation process.

Incidentally, the cap 24 is not limited to a cap having a two-stage recess as shown in the drawing, but may be a simple plate-shaped cap.

F. Effects of the Invention According to the present invention, fluid injection is used for fluid filling operation in a thin film EL panel in which a thin film EL element and its insulating protective fluid are housed in an envelope consisting of a translucent front substrate and a back plate. Since only one injection tube can be used repeatedly, the manufacturing process can be simplified. In addition, since a stretchable thin plate is used to seal the fluid injection hole, and the thin plate is covered with a cap with a recess for sealing, damage to the injection hole sealing part due to thermal expansion of the fluid is prevented, and the sealing This ensures that the moisture resistance of the panel improves. Furthermore, since a packing material having a hole with a smaller diameter than the injection hole is adhesively fixed to the injection hole, fluid leakage is prevented when fluid is injected or when the injection tube is removed.Moreover, the thickness of the packing material allows a cap with a concave portion to cover the thin plate. This is advantageous in allowing for dimensional tolerances in cap height.

[Brief explanation of drawings]

Figure 1 is a schematic side sectional view of a thin film EL element, Figure 2 is a schematic plan view of its transparent electrode and back electrode, Figure 3 is a schematic side sectional view of a conventional thin film EL panel, and Figure 4 is its fluid injection. A side sectional view of the rear glass plate during the operation process, FIGS. 5a and 5b are explanatory diagrams of the fluid injection operation, FIGS. 6a, b, and c are explanatory diagrams of the fluid injection tube sealing operation, and FIG. 7 8 is a side sectional view of the sealed portion double-sealed with a cap with a concave portion, FIG. 8 is a rear glass plate used in the thin film EL panel according to the present invention, and FIGS. 9 and 10 are Fig. 11 is a partial side sectional view of the back glass plate when the packing material is adhesively fixed to the back glass plate, and Fig. 11 is a partial side sectional view of the back glass plate when the external injection tube is inserted into the back glass plate. Figures a and b are explanatory diagrams of the fluid injection operation of the thin film EL panel according to the present invention, Figure 13 is a partial schematic side sectional view of the thin film EL panel after the injection operation is completed, and Figure 14 is an illustration of the injection hole with a thin plate. Partial schematic side sectional view of a sealed thin film EL panel according to the present invention, No. 15
Figure a is a side view of an example of the thin plate, Figure 15b is a plan view thereof, Figure 16a is a sectional view of a thin plate of other shapes, Figure 16b is a plan view thereof, and Figure 17 is its plan view. A partial schematic side cross-sectional view of a thin film EL panel according to the present invention in which a thin plate is double-sealed with a cap with a recess, FIG. 18 is a cross-sectional view of an example of the cap with a recess, and FIG. 19 is a recess having another shape. FIG. 3 is a sectional view of the attached cap. 1... Translucent front substrate, 9... Thin film EL element,
DESCRIPTION OF SYMBOLS 10... Rear plate, 11... Envelope, 12... Insulating protective fluid, 13... Injection hole, 19... Packing material, 23... Thin plate, 24... Cap with recess.

Claims (1)

[Claims] 1. In a thin film EL panel in which a thin film EL element and an insulating protective fluid for the thin film EL element are housed in an envelope consisting of a translucent front substrate and a back plate, the protective fluid provided in the envelope is A packing material having a hole smaller in diameter than the injection hole is concentrically arranged and adhered to the injection hole, the hole in the packing material is sealed with a deformable thin plate, and the thin plate is sealed with a cap with a recess. A thin film EL panel characterized by: