JPS62295090A - Field light emitting display panel and manufacture thereof - 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 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an electroluminescent display panel (hereinafter abbreviated as an EL panel), and in particular, to prevent dielectric breakdown and phosphor layer formation. The present invention relates to an EL panel that has a longer lifespan by preventing brightness deterioration, and a method for manufacturing the same.

[Prior Art] Generally, an EL panel is manufactured by applying a strong electric field (10'V/cm or more) to a light-emitting layer consisting of a dielectric layer containing a phosphor, thereby causing a conductive part on the surface of the phosphor to interact with the dielectric layer. Display is performed by moving electrons generated at the interface with the light-emitting layer and electrons existing in the light-emitting layer, causing them to collide with the light-emitting center and causing them to emit light with excitation.

Currently, various types of EL panels have been proposed, but thin-film AC-driven EL panels are considered promising in terms of lifespan and luminance, and some have even been put into practical use. .

FIG. 6 is a schematic cross-sectional view showing the structure of a typical EL panel. Here, 101 is a substrate made of a transparent material such as glass, and one surface (upper surface in the figure) of this substrate 101 is coated with an S no 2 thin film or ITO (ITO).
nd i un -T i n -Ox i d e)
A translucent electrode 102 such as i''jnQ is formed.A first dielectric layer 103 made of Y203 or the like is formed on this electrode 102.A light emitting layer containing a phosphor such as ZnS:Mn is formed on this electrode 102. 104 and a second dielectric layer 105 are sequentially laminated and encapsulated by means such as vacuum evaporation, sputtering, or electron beam evaporation.

Note that an EL panel having a structure in which a :J5 electric layer is provided only on one side of a light emitting layer is also known. Furthermore, the second dielectric layer 1
A back electrode 106 such as an A2 film is formed on the 05. If a dot matrix display is to be performed using an EL panel, the electrode 102 and the back electrode 106 are as follows.
The back electrode 106 and the electrode 102 are connected to a drive circuit section 107, etc., and a display signal is applied to the back electrode 106 and the electrode 102. It is configured so that

In general, EL panels with the above-mentioned configuration have many defects such as pinholes and cranks in the thin film due to minute dust that is difficult to completely eliminate during the manufacturing process, and therefore are difficult to resist moisture. In other words, in a multi-layered structure like the one shown in Figure 6, if there are pinholes in the thin film, water will penetrate through the holes and cause damage to the living room 2II.
# may occur. Then, as the operating time passes, 211 M'i ja expands and is observed as a non-light-emitting point in one light-emitting pixel. Furthermore, the penetration of moisture may cause dielectric breakdown.

As a solution to these problems, an EL panel with a moisture-proof structure as shown in FIG. 7 has been proposed. Tooru IJ
On the I substrate 108, a transparent electrode 109, a first dielectric layer 110, a light emitting layer 111 . Then, second dielectric layers 112 are sequentially laminated. Furthermore, the transparent electrode 1
Back electrodes 113 arranged parallel to each other in a direction perpendicular to 09 are provided on the second XAtTt body layer 112, and a thin film type electroluminescent device (hereinafter abbreviated as a thin film EL device) is constructed. has been done. In order to fix this thin film EL element 11, a back plate 115 is placed opposite to the transparent substrate 108 with a spacer 114 in between. The thin film EL element is fixedly sealed and sealed to form an outer envelope for housing the t'M film EL element.Silicon oil 117 is sealed in the envelope to protect the thin film EL element. ing.

[Problems to be Solved by the Invention] In the EL panel shown in FIG. 7, moisture is also present in the silicone oil 117, and the resin adhesive 116 that cannot completely block out moisture is used in the backing. Face plate 115・
Since the spacer 114 and the transparent substrate 108 are of the same nature, the moisture-proofing effect is not sufficient and the reliability cannot be said to be high.

Moisture-proofing treatments for thin-film EL elements include the above-mentioned method, applying an organic film to the back electrode 113 for sealing, and applying an insulating thin film such as A-203 to the back electrode 113. Although other methods have been considered, none of these methods have been established to the point where they can be effective.

[Objective of the Invention] An object of the invention is to provide an electroluminescent display panel that has a long life and high reliability due to its excellent moisture-proofing effect, and a method for manufacturing the same.

[Structure of the Invention] The electroluminescent display panel of the present invention is an electroluminescent display panel in which an electroluminescent element is formed in an airtight container constituted by a front plate made of a translucent material and a rear container part,
It is characterized by a structure in which a front plate made of a translucent material such as glass and a back container part made of a material 1 which does not allow moisture to pass through, such as glass, are hermetically sealed with low melting point solder glass. Further, the method for manufacturing an electroluminescent display panel of the present invention includes a step of laminating an electroluminescent element on one surface of a front plate, and a peripheral portion of the front plate or a rear container portion forming an airtight container together with the front plate. a step of forming a low-melting point solder glass layer on at least one of the opposing peripheral edges of the holder, and a step of heat-treating and degassing the front plate and the rear container by placing them in a vacuum atmosphere or a gas atmosphere containing almost no moisture. Then, a predetermined amount of gas is introduced into the space of the front plate and the rear container part, or a high vacuum condition is applied! The method is characterized in that it includes a step of exhausting the glass, heating the solder glass to a temperature at which the low melting point solder glass melts, and airtightly sealing the front plate and the rear container part. Another method of manufacturing an electroluminescent display panel of the present invention includes the steps of laminating an electroluminescent element on one surface of a front plate, and the periphery of the front plate or the rear side forming an airtight container together with the front plate. a step of forming a low-melting-point turquoise layer on at least one of the peripheral edges of the container portion facing the front plate; and a step of overlapping the front plate and the rear container portion and placing them in a vacuum or gas atmosphere for heat treatment and desorption. With the process of performing gas.

Introducing a predetermined amount of gas into the space in which the front plate and the rear container are arranged, heating and raising the temperature to a temperature at which the low melting point solder glass melts, and airtightly sealing the front plate and the rear container. and an evacuation step of evacuating the inside of the airtight container to a high vacuum state through an evacuation hole previously formed in the rear container portion, and then closing the evacuation hole.

[Function] First, an electroluminescent element is laminated on one side of a front plate made of glass or the like.Next, the periphery of the side on which the electroluminescent element is formed or the back side made of glass 7 or the like is laminated. A low melting point solder glass layer is formed on at least one side of the opposing periphery of the container part. Next, the front plate and the rear container portion are placed in a vacuum atmosphere or a gas atmosphere, and heated to an appropriate temperature to release the gas in the glass to perform degassing.

In one manufacturing method, a predetermined amount of gas containing almost no moisture is introduced into the space in which the front plate and the rear container are arranged, or the gas is evacuated to a high vacuum state, and then the low melting point solder glass is formed. The front plate and the rear container portion are hermetically sealed by heating to a temperature at which they melt. In the other manufacturing method, following the degassing described above, a predetermined amount of gas is introduced into the space in which the front plate and the rear container are arranged and heated to a temperature at which the low melting point solder glass melts. warm it up,
The front plate and the rear container portion are tightly sealed. And vr
The inside of the airtight container is evacuated to a high vacuum state through the airless hole, and the exhaust hole is closed.

In the electroluminescent display panel manufactured as described above, the front plate and the rear container are completely hermetically sealed with low melting point solder glass that completely blocks moisture, and the EL element is placed in the internal space. stored, and the corresponding EL
The device is protected by a high vacuum atmosphere or by a dehydrated gas. Therefore, this electroluminescent display panel has a long life and high reliability because the moisture-proofing effect of the EL element is poor.

[Example] FIGS. 1 to 5 show an EL which is an example of the present invention.
The manufacturing process of the panel will be explained.

To explain the manufacturing process of the EL element 2 which becomes the light emitting part of the EL panel 1, first, as shown in FIG. Let it form. This transparent electrode 4 is strip-shaped,
They are provided parallel to each other at predetermined intervals. Then, the transparent electrode 4 is
A thin film of Y2O3 is deposited thereon to form the first dielectric layer 5. Then, in the formation of the light-emitting layer 6, a ZnS:Mn phosphor is deposited thereon by high-frequency Svanta deposition method to form the light-emitting layer 6.

Heating the glass substrate 3 to 200°C in an Ar gas atmosphere,
After forming 6 light emitting layers 6 with high frequency output of 150W,
In order to activate the light-emitting layer 6, the glass substrate 3 is heat-treated at about 500° C. for 1 hour in a vacuum or a neutral gas atmosphere. (This operation is referred to as 7-neel.) Then, a thin film of Y203 is deposited on the light emitting layer 6 to form the second dielectric layer 7. And further, the second vLJ''
M. A pattern A is vacuum-deposited on the body layer 7 to form the back electrode 8. The back electrodes 8 are strip-shaped and are formed parallel to each other at predetermined intervals. The longitudinal direction of each back electrode 8 is perpendicular to the longitudinal direction of the transparent electrode 4, so that a dot matrix display can be performed. and,
on the upper surface of the back electrode 8.

An insulating film 9 made of A pattern 203 or the like is deposited.

Make sure that the back electrode 8.8 does not short-circuit.

Next, a description will be given of the rear container portion lO that covers the EL element 2 manufactured as described above. As shown in Figure 2,
The rear container part 10 is a dish-shaped container with one side open.
The size must be large enough to cover the ELi element 2. The illustrated embodiment has an integral structure with a U-shaped cross section, but it is constructed by bonding or assembling a plurality of glass materials with low melting point solder glass. Also, the rear container part l
The material of O is glass 0426 alloy (42Njφ6Cr・
The low melting point sulter glass 11, which is preferably made of metal ceramics such as Fe), which has a melting point lower than the strain point of this glass material and has an almost equal expansion coefficient, is placed in the rear container part 1.
This low melting point solder crow 11 is attached in advance to the end surface 10a of the opening periphery of the glass substrate 3, or to a position on the glass substrate 3 where the end surface 10a of the rear container section 10 comes into contact.

Next, the glass substrate 3 on which the EL element 2 is formed and the rear container part 10 are placed in a vacuum chamber 12. A vacuum evacuation system 15 consisting of a rotary pump 13 and a differential pump 14 is connected to the vacuum chamber A-12. Further, an introduction pipe 16 for introducing gas into the vacuum chamber 12 is connected and communicated with the vacuum chamber 12, and the introduction pipe 16 outside the vacuum chamber 12 is provided with a dehumidifying material 16a and a valve 16b. Further, inside the vacuum chamber 12, a fixed table 17 having a heater 17a and a movable table 18 having a heater 18a which is vertically movable above the fixed table 17 are provided.

Now, the glass substrate 3 is attached to the movable base 18 with the EL element 2 facing downward, and the rear container portion 10 is installed at a predetermined position on the fixed base 17 so that the end surface 10a faces upward. and,
The vacuum exhaust system 15 is driven to bring the inside of the vacuum chamber 12 into a high vacuum state, and the glass substrate 3 and the back container part 10 are heated using the heaters 17a and 18a to a temperature just before the low melting point solder glass 11 is softened. The gas that is degassed, which is generally stored in glass, is more than 90% water, and the maximum temperature is 200'C for lined glass and 300'C for non-alkali glass (silicate glass, etc.). It is said that many gases are generated, namely:
The degassing temperature is preferably 300'C or higher. Also,
In this degassing treatment, by raising the temperature of only the glass substrate 3 to about 500° C., annealing, which is necessary for manufacturing the EL element, can be performed at the same time in this step, and the number of steps can be reduced.

Thereafter, the rear container portion 10 is heated using the heater 17a to raise the temperature to a temperature equal to or higher than the softening point of the low melting point solder glass 11. The temperature of the glass substrate 3 is adjusted using the heater 18a so that the temperature is approximately the same as that of the rear container portion 10. Then, the movable table 18 is moved downward, and the glass substrate 3 is pressed against the rear container part 10 to seal them together. Thereafter, the temperature is lowered to solidify the low melting point solder glass 11.

In addition, when the airtight container becomes large in size, gas at a predetermined pressure may be introduced into the EL panel 1 in order to provide pressure resistance.
b is opened, and inert gas such as argon or nitrogen, carbon dioxide gas, oxygen, etc. are introduced into the vacuum chamber 12 through the introduction pipe 16.

At this time, the gas introduced is a gas with extremely low moisture obtained by vaporizing liquefied gas, a gas compressed under high pressure to remove moisture, or a moisture-absorbing material such as molecular sieve or activated alumina.
6a to dehumidify it. The pressure of the introduced gas only needs to be about 1.0 to 3 atm.The sealing process is then carried out to reduce the EI inside the panel 1 to 0.4 to 3 atm.
The pressure can be maintained at approximately 1.6 atmospheres, resulting in a panel with excellent positive properties.

Further, an exhaust hole is provided in advance in the rear container section, and the glass substrate serving as the front plate and the rear container section are placed in a sealed tube device similar to the vacuum chamber 12 with the glass substrate as the front plate and the rear container section aligned and aligned. After the substrate and the rear container part are sealed at their peripheral edges, the exhaust hole may be hermetically sealed with a lid member placed separately. It may be formed with a spacer, and the EL element part is usually very thin (1 to 10 g,
m), it can also be formed using only plate glass and low melting point solder glass.

FIGS. 4(a) to 4(d) show EL panels la, lb, and lc produced by the various methods described above.

The schematic configuration of 1d is shown.

In FIG. 4(a), an exhaust hole 19a is formed in advance in the dish-shaped rear container part 19, an exhaust pipe 20 is provided here, and after the substrate 21 and the rear container part 19 are sealed, the inside is opened. This is an example in which the exhaust pipe 20 is sealed under high vacuum or a predetermined gas pressure. In the EL panel shown in Figure 4 (α), a getter such as a Ba getter is provided in an airtight container. By providing this getter, it is possible to absorb gas such as H2O released from the EL element itself, the inner wall of the container, etc. during operation of the EL panel, and the moisture-proofing effect can be further enhanced.

Further, in FIG. 4(a), a getter (G) is provided to adsorb moisture released from the inner wall of the container or from the EL element itself during operation of the EL element.

FIG. 4(b) shows an example in which the exhaust pipe is replaced with an exhaust lid 22, and FIG. 4C shows an example in which the rear container portion 23 is constructed of a flat plate member 24 and a spacer 25 or low melting point solder glass. , FIG. 4(d) shows an example in which the rear container portion 26 is made of a fully bendable member such as 426 alloy. In FIG. 4, for convenience of explanation, E L ;i child 2a is shown by an imaginary line.

In the EL panel 1 of this embodiment, the glass back container portion 10 and the glass substrate 3 are heated and degassed before assembly. These are hermetically fixed with a low melting point solder glass 11 that does not allow any moisture to pass through, thereby forming an airtight container in which the EL element 2 is housed.

Further, the inside of the airtight container is filled with a high vacuum state or with gas from which moisture has been removed to protect the EL element 2. Unfortunately, moisture does not enter the hermetically sealed container during use, and the EL and II elements 2 are always maintained completely free of moisture. Therefore, this EL panel 1 is particularly excellent in moisture proofing of the EL elements 2, so it has a long life and is highly reliable.In addition, each EL panel la, lb,
As with the EL panel 1, high reliability can be expected for the IC and ld.

By the way, one of the major reasons why a conventional EL element has a double insulation structure in which a light emitting layer 104 is sandwiched between dielectric layers 103 and 105 as shown in FIG. 6 is for moisture proofing. However, this dielectric layer 103,1
05 is one of the reasons why the drive voltage must be increased.

On the other hand, in each EL panel according to the present invention described above, the EL panel is housed in a container completely hermetically sealed with low melting point solder glass.
This is a structure in which the element is encapsulated.

Therefore, in the EL panel of the present invention, since moisture is completely prevented from entering the EL element, the moisture-proof structure of the element itself becomes less important.

That is, as in the EL panel 1e shown in FIG. 5, a laminated structure of the transparent electrode 4, the light emitting layer 6, the dielectric layer 7, and the back electrode 8 can provide sufficient life characteristics.

In the structure shown in FIG. 5, since there is even less truncation and isolation, it is effective in lowering the driving voltage.

Although the EL panels in each of the embodiments described above are AC thin film EL panels, the present invention can be applied to various types of EL panels, and the structure of the EL element is not limited to the illustrated example. No. 6 For example, the present invention is a monodispersion type E
It can also be applied as a moisture-proof structure of an L panel or a manufacturing method thereof.

Further, the material of the rear container part is not limited to glass, but as described above, a material having a coefficient of thermal expansion close to that of the glass substrate 3 and the low melting point solder glass 11, such as a 42-6 alloy known as a sealed tube alloy. You may also use

[Effect of the invention] Moisture that is harmful to the EL element can be completely removed;
It is possible to completely prevent dielectric breakdown and reduction in brightness of EL elements caused by moisture, and improve the reliability of the EL panel.

In the process of degassing the back container part and the front plate, by increasing the temperature only for the front plate, annealing, which is necessary for manufacturing the EL element, can be performed at the same time, so the number of steps can be reduced.

Furthermore, the structure of the EL element can be simplified and the driving voltage can be reduced.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an EL element in an embodiment of the present invention,
FIG. 2 is a diagram showing the assembly process of the rear container part in the same embodiment, FIG. 3 is a schematic diagram showing the manufacturing process of the same embodiment, and FIG.
FIG. 5 is a cross-sectional view of an EL panel showing another embodiment of the present invention, and FIG. 5 is a cross-sectional view of an EL panel having a simplified EL element structure. Figure 6 is a schematic cross section showing the structure of a typical EL panel;
The figure is a sectional view of a conventional EL panel. 1, la, lb, lc, lcl, 1e-EL panel (
(electroluminescent display panel), 2.2a... EL element (electroluminescent element), 3... glass substrate as front plate, lO
...Back container part, 11...Low melting point solder glass,
19... Back container part, 21... Substrate as a front plate, 23.26... Back container part.

Claims (7)

[Claims] (1) In an electroluminescent display panel in which an electroluminescent element is formed in an airtight container constituted by a front plate and a rear container made of a translucent material, the front plate and the rear container are made of low melting point solder glass. An electroluminescent display panel characterized in that it has a hermetically sealed structure. (2) The electroluminescent display panel according to claim 1, wherein electroluminescent elements are directly laminated on the inner surface of the front plate. (3) The electroluminescent display panel according to claim 1 or 2, wherein the airtight container is evacuated to a high vacuum state. (4) The electroluminescent display panel according to claim 1 or 2, which has a structure in which gas is sealed in the airtight container. (5) The pressure of the gas in the airtight container is between 0.4 atm and 1.0 atm.
The electroluminescent display panel according to claim 4, which has a pressure of 6 atmospheres. (6) a step of laminating an electroluminescent element on one surface of the front plate; and a step of laminating an electroluminescent element on one side of the front plate; a step of forming a low melting point solder glass layer on one side of the two; a step of overlapping the front plate and the rear container portion and placing them in a vacuum or gas atmosphere to perform heat treatment and degassing; The space in which the solder glass is placed is evacuated to a high vacuum state, or a predetermined amount of gas is introduced, and the temperature is raised to a temperature at which the low melting point solder glass melts, thereby airtightly sealing the front plate and the rear container part. A method for manufacturing an electroluminescent display panel, comprising the steps of: (7) a step of laminating an electroluminescent element on one surface of the front plate; and a step of forming an electroluminescent element on one side of the front plate; a step of forming a low melting point solder glass layer on one side; a step of overlapping the front plate and the rear container portion and placing them in a vacuum or gas atmosphere to perform heat treatment and degassing; A step in which a predetermined amount of gas is introduced into the space in which the low melting point solder glass is arranged is heated to a temperature at which the low melting point solder glass melts, and the front plate and the rear container portion are hermetically sealed. After evacuating the inside of the airtight container to a high vacuum state through the exhaust hole formed in the
A method for manufacturing an electroluminescent display panel, comprising the step of: closing the exhaust hole.