JPS63226684A - Electric field light emitting display panel - 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 an electroluminescent display panel (hereinafter abbreviated as EL panel), and in particular, the present invention relates to an electroluminescent display panel (hereinafter abbreviated as EL panel), and in particular, by preventing dielectric breakdown and brightness deterioration of a fluorescent layer. This relates to an EL panel that has a longer lifespan.

[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, and causing them to collide with the light-emitting center to excite and emit light.

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. 10 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 of this substrate 101 (
The top surface in the figure) is coated with a Sn02 thin film or an ITO
A translucent electrode 102 such as a (Indium-Tin-Oxide) thin film is formed. And this electrode 10
2, a first dielectric layer 103 made of Y203 etc.
A light-emitting layer containing a phosphor such as , ZnS:Mn! 04 and 2nd
The dielectric layer 105 is formed by a vacuum evaporation method, a sputtering method,
Alternatively, they are sequentially deposited in layers by means such as electron beam evaporation. Note that EL panels having a structure in which a dielectric layer is provided only on one side of a light emitting layer are also known. Further, on the second dielectric layer 105, a back electrode 8i10 such as an A1 film is provided.
6 is formed. If a dot matrix display is to be performed using an EL panel, the electrode 102 and the back electrode 106 may be formed in the form of stripes, and their arrangement directions may be orthogonal to each other. The back electrode 106 and the electrode 102 are connected to a drive circuit section 107 and the like, and are configured to be supplied with a display signal.

In general, EL panels with the above-mentioned configuration have many defects such as pinholes and cracks 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. is very weak. That is, in a multilayer structure as shown in FIG. 10, if there are pinholes or the like in the thin film, moisture may penetrate through the pinholes and cause delamination. Then, as the operating time passes, the peeled area expands and is observed as a non-light-emitting point in the light-emitting pixel. Furthermore, penetration of moisture may cause dielectric breakdown.

To solve these problems, a cover glass is glued onto the substrate on which the EL element is formed.
Attempts have been made to improve the reliability of EL panels by covering the EL elements and sealing silicone oil in the cover glass to shield the EL elements from moisture and the like. However, this method cannot completely block out moisture due to the presence of moisture in the silicone oil and the use of epoxy resin to bond the substrate and cover glass, so it is not reliable enough. It's hard to say.

Therefore, as a measure to prevent deterioration of EL elements due to moisture, etc., the applicant of the present application has proposed an EL panel having a structure as shown in FIG. 11.

In this EL panel, a rear container part 202 is sealed around a substrate 201 using low melting point solder glass to form an envelope, and an electroluminescent element 203 (hereinafter abbreviated as EL element 203) is placed inside the envelope. ).

The inside of the envelope is vacuumed or a dry inert gas or the like is introduced.

In this case, since it is necessary to supply a driving signal to the EL element 203 from the outside, the external terminal passes through the sealed portion between the substrate 201 and the rear container portion 202.

Now, FIG. 12 shows a schematic enlarged view of the lead-out portion of the external terminal of this EL panel. Figure 12 shows
This is an EL panel that uses an X-Y matrix electrode type to display graphics, etc., and an electrode 204 in the X direction and an electrode 205 in the Y direction are arranged to intersect with each other with an EL element 203 in between. When observing the display from the substrate 201 side, the electrode 204 is formed as a transparent electrode using a material such as SnO2 or ITO. Electrode 205 is typically an AIL deposited film.

These electrodes 204 and 205 are extended as they are to the periphery of the substrate to serve as external terminals. Then, low melting point solder glass 206 is applied onto the external terminals as shown by diagonal lines in the figure, and the rear container portion 202 is sealed.

[Problems to be Solved by the Invention] However, in the EL panel configured as described above, the low melting point solder glass 206 that seals the rear container portion 202 to the substrate 201 is not connected to the electrode 2 made of A1, ITO, etc.
There was an interlayer point that corroded the 04, 205 and deteriorated its electrical characteristics. The reason for this is that PbO in the low melting point solder glass 206 has an oxidizing effect, and the components in the glass that become liquid during sealing oxidize, for example, the A 1 Ti electrode, converting A2 into A It 20 z
This is thought to be due to the fact that it diffuses into the glass in the form of Possible countermeasures include increasing the thickness of the AIL electrode and using a low melting point solder glass other than PbO. However, in the method of increasing the thickness of the A1 electrode, as is clear from FIG.
, 205 are formed all at once, so if the external terminal portion is made thicker, the electrode portion will also become unnecessarily thicker.

Also, the thickness of A1 needs to be 11000n or more,
If the AIt is made thick in this manner, when dielectric breakdown occurs in the element, there is a greater risk that the melted AIt will come into contact with the base electrode and develop into a catastrophic dielectric breakdown. EL element 2
It is possible to leave the electrode portion of 03 as is and make only the external terminal portion thicker, but this would complicate the process and is not preferable. On the other hand, Z
Although there are nO-based materials, there are currently no usable materials in terms of melting point or reliability.

In addition, AIL using glass with low PbO.

Another possible method is to form a so-called cross layer on the ITO electrodes to reduce the degree of corrosion of these electrodes. but,
Since this method requires heat treatment at a relatively high temperature and the glass contains a considerable amount of PbO, it is not considered to be a fundamental solution to the corrosion.

[Purpose of the invention] The purpose of the invention is to provide an electroluminescent display panel that has a long life and is highly reliable due to its excellent moisture-proofing effect, and in particular, the purpose of the invention is to The object of the present invention is to realize an electroluminescent display panel whose electrical characteristics are not adversely affected by the low melting point solder glass used for sealing.

[Means for Solving the Problems] In the electroluminescent display panel of the present invention, a container portion is hermetically sealed around the periphery of a substrate on which an electroluminescent element is formed, and a signal is transmitted to the electroluminescent element via an external terminal. An electroluminescent display panel that obtains a display by applying a It is characterized by a structure in which it comes into contact with the ends of each electrode.

[Example] Embodiments of the present invention will be described with reference to FIGS. 1 to 9.

As shown in FIG. 1, on the transparent glass substrate 3,
Electroluminescent display panel! (Hereinafter referred to as EL panel 1.)
An electroluminescent element 2 (hereinafter referred to as EL element 2), which serves as a light emitting portion, is formed. First, a plurality of (two are shown in the figure) transparent electrodes 4 made of rTOlli are adhered to the upper surface of the substrate 3, and the transparent electrodes 4 are strip-shaped and spaced apart at predetermined intervals. are parallel to each other. A light emitting section 5 is formed on the transparent electrode 4. Although details are not shown, this light emitting section 5 is
a first dielectric layer made of, for example, Y 20 ), deposited on the transparent electrode 4; a light emitting layer made of, for example, ZnS:Mn phosphor, deposited on the dielectric layer; and a second dielectric layer made of, for example, Y2O3, deposited on the light emitting layer. And the light emitting part 5
On top of the second dielectric layer of aluminum? A back electrode 6 made of an i1m layer is deposited. The back electrodes 6 are band-shaped electrodes arranged parallel to each other at predetermined intervals, and are arranged in a direction perpendicular to the transparent electrode 4. -A Y matrix type electrode group is configured. The back electrode 6 is continuously formed on the side of the light emitting section 5 and the surface of the substrate 3, but does not extend to the edge of the substrate 3. That is, a space is left on the surface of the substrate 3 between the edge of the back electrode 6 and the edge of the substrate 3, and as will be described later, the container part 7 is placed on the substrate 3 so as not to touch the back electrode 6. It can be sealed and fixed. Although not shown, the transparent electrode 4 is also similar to the back electrode 6, and a container portion 7 is sealed and fixed on the substrate surface between the end of the transparent electrode 4 and the edge of the substrate 3. There is space left for.

Next, on the side of the substrate 3 where the EL element 2 is formed,
The container part 7 is sealed and fixed with a low melting point solder glass 8, and the inside thereof is maintained in a high vacuum state. In this embodiment, as described later, the external terminal 9 also serves as a spacer between the substrate 3 and the container part 7, so the container part 7
A flat glass plate is used for this purpose. The material of the container portion 7 is preferably the same as that of the substrate 3 in terms of thermal expansion coefficient. Furthermore, the low melting point solder glass 8, which is a sealing material, is made of a material whose melting point is lower than that of the substrate 3 and the container portion 7, and whose thermal II tensile coefficient is approximately equal to stiffness.

Next, a metal external terminal 9 is hermetically passed through and fixed to the sealed portion of the low melting point solder glass 8. The external terminal 9 is a long and thin metal plate, and the inside of the container 10 is
It is bent into a letter shape and has elasticity. Since the free end 10a of the inner end portion 10 of the container is pressed against the container portion 7, the corner of the bent portion 10b exerts a predetermined elastic force on the end portion of the back electrode 6 and is stabilized. It is in contact with and conducts to. That is, this external terminal 9 contacts both the back electrode 6 of the substrate 3 and the container portion 7, and also serves as a spacer for providing a gap of a predetermined size between the substrate 3 and the container portion 7, both of which are flat. . The material of the external terminal 9 may be, for example, a 42Ni-6Cr-Fe alloy having a coefficient of thermal expansion substantially equal to that of the glass when the substrate 3 is made of glass. In addition, the material of the substrate 3 etc. is aluminosilicate glass, etc.
When using glass with relatively low expansion, for example, 42N
1-Fe, 29N i-17Co-Fe alloy, etc. can be used. Furthermore, the external terminal 9 has an oxide layer formed on its surface by hydrogen treatment, and is coated with low melting point solder glass 8.
It is becoming easier to get used to.

In addition, the thickness of the external terminal 9 should be 0.002 layers or more for corrosion caused by the low melting point solder glass 8, but from the viewpoint of ease of post-processing (soldering, etc., press molding, etc.), It is appropriate to set it at 0.05 to 1 stirrup.

Next, another embodiment of the present invention will be described, focusing on the parts that differ from the first embodiment. Components similar to those in the first embodiment are given the same reference numerals as in FIG. 1, and description thereof will be omitted.

First, a second embodiment of the present invention will be described. As shown in FIG. 2, in the EL panel 1a of this embodiment, the shapes of the external terminals 12 and the container portion 11 are different from those of the first embodiment. The container portion 11 of this embodiment has a box shape with an open bottom side, and is sealed and fixed to the edge portion of the substrate 3 with a low melting point solder glass 8. Furthermore, the external terminal 12 that passes through the low melting point solder glass 8 in an airtight manner brings the tip 13a of the hook-shaped container inner end 13 into contact with the end of the back electrode 6. The inner end portion 13 of the container is not press-worked into a springy shape as in the previous embodiment, but the external terminal 12 sandwiched between the container portion 11 and the substrate 3 is connected to the inner end portion 13 of the container. Since it is fixed in a pressed state by 11, it is in a state of stable contact and conduction with the back electrode 6.

Next, a third embodiment of the present invention will be described. As shown in FIG. 3, the EL panel of this example! The container portion 7a of FIG. b has the same flat plate shape as in the first embodiment, and an elongated thin plate-like external terminal 14 hermetically passes through the sealed portion between the container portion 7a and the substrate 3a and is connected to the rear surface inside the container portion 7a. "iHM6 is in contact with and conductive to the end of the container. The inner end of the container pHt s of the external terminal!4 is press-molded into a dogleg shape to provide spring properties, and the corner 15b of the bent portion is connected to the container part 7a. Since it is in a state where it is in contact with the inner surface and pressed, the end portion 15a of the inner end portion 15 of the container is securely in contact with the end portion of the back electrode 6.

Next, EL panel 1 explained above. The manufacturing process of la and lb will be explained by taking the EL panel 1a of the second embodiment as an example.

First, a plurality of transparent electrodes 4 made of ITO film are placed on a substrate 3.
is deposited and formed. Then, a thin film of Y2O3 is deposited on the transparent electrode 4 by a technique such as electron beam evaporation to form a first dielectric layer. And on top of this, ZnS
:Mn phosphor is deposited by high frequency sputter deposition method to form a light emitting layer. In forming the light emitting layer, the substrate 3 was heated to 200°C in an Ar gas atmosphere, and the high frequency output was set to 150W. After forming the light-emitting layer, the substrate 3 is heat-treated at about 500° C. for 1 hour in vacuum or in a neutral gas atmosphere in order to activate the light-emitting layer. (This operation is called annealing.) Then, place Y20 on the light emitting part.
:1 thin film is deposited to form a second dielectric layer. Then, 81 is further vacuum-deposited on the second dielectric layer to form a back electrode 6.

Next, as shown in FIG. 4, in order to improve the adhesion between the board 3 and the external terminals 12, a low melting point solder is applied in advance to a part of the external terminals 12 that will be adhesively fixed to the sealed part of the board 3 and the container part 11. Glass 8 is applied and pre-fired. Further, as shown in FIG. 6, a low melting point solder glass 8 is also applied in advance to the open end surface of the container portion 11 to be bonded to the substrate 3, and pre-firing is performed. Note that even when manufacturing the EL panel 1 having the structure as in the first embodiment, as shown in FIGS. Coat and pre-fire.

Next, as shown in FIG. 8, the substrate 3 on which the EL element 2 is formed and the container part 11 whose open end surface is coated with low melting point solder glass 8 are placed in a vacuum chamber 16. A vacuum evacuation system 19 consisting of a rotary pump 17 and a differential pump 18 is connected to the vacuum chamber 16 . Further, an inlet pipe 20 for introducing gas into the vacuum chamber 16 is connected and communicated with the inlet pipe 20 outside the vacuum chamber 16, and a dehumidifying material 21 and a valve 22 are connected to the inlet pipe 20 outside the vacuum chamber 16.
is provided. Further, inside the vacuum chamber 16, there are provided a fixed table 24 having a heater 23, a movable table 25 which is vertically movable above the fixed table 24, and a halogen lamp 26 for heating.

Now, the substrate 3 is installed in the recess 24a of the fixing base 24 so that the EL element 2 faces upward. Then, each external terminal 12 is attached to the fixed bin 24b on the upper surface of the fixed base 24, and each tip 13a of the container inner end 13 is brought into contact with the end of the plurality of transparent electrodes or back electrodes on the substrate 3, and each external terminal The low melting point solder glass 8 applied to the terminal 12 in advance is placed at the position where the substrate 3 and the container part 11 are sealed. Then, the container part 11 is attached to the movable base 25 so that the open end coated with the low melting point solder glass 8 faces downward. Then, the vacuum evacuation system 19 is driven to bring the inside of the vacuum chamber 16 into a high vacuum state, and the substrate 3 and the container part 11 are heated using the heater 23 and the halogen lamp 26 to a temperature just before the low melting point solder glass 8 becomes soft. and preach gas. Generally, the gas occluded in glass is 90
% or more is water, and it is said that the largest amount of gas is generated at a temperature of 200°C for lined glass and around 300°C for non-alkali glass (silicate glass, etc.).

That is, it is desirable that the degassing temperature is 300° C. or higher.

Further, in this degassing treatment, if the temperature of only the substrate 3 is raised to about 500° C., annealing 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, using the heater 23 and the halogen lamp 26, the temperature of the container portion 11, the substrate 3, and the external terminals 12 is raised to a temperature equal to or higher than the softening point of the low melting point solder glass 8. And the movable table 25
is moved downward, and the container portion 11 is pressed against the substrate 3 to seal them together. Thereafter, the temperature is lowered to solidify the low melting point solder glass 8.

Further, when the airtight container is enlarged, gas at a predetermined pressure may be introduced into the EL panel la in order to provide pressure resistance. In this case, the pulp 22 is opened before sealing, and the pulp 22 is passed through the vacuum chamber 16 through the introduction pipe 20.
Inert gas such as argon or nitrogen, carbon dioxide gas, oxygen, etc. are introduced into the chamber. At this time, the gas to be introduced is one that has been vaporized from liquefied gas and has extremely low moisture, one that has been compressed to high pressure to remove moisture, or one that has been dehumidified by passing through a moisture absorbing material 21 such as molecular sieve or activated alumina. do. The pressure of the introduced gas may be about 1.0 to 3 atm. After that, by performing a sealing process, the EL panel la
The internal pressure can be maintained at approximately 0.4 to 1.6 atmospheres, resulting in a panel with excellent pressure resistance. In this case, after sealing, until the temperature at which the low melting point solder glass 8 hardens is reached, the temperature difference between the inside and outside of the container section 11 should be avoided.
It is necessary to appropriately adjust the pressure inside the vacuum chamber 16 to 1Ji2i.

In each embodiment and an example of the manufacturing process described above, a large number of external terminals 9, 12, 14 are formed as independent components,
Assembling each piece is a time-consuming task. Therefore, as shown in FIG. 9, if each external terminal 27 is integrally formed by pressing or the like so that it is connected to a common frame 28, each external terminal 27 can be connected to the end of each electrode on the board 30. The positioning work of the terminal 27 becomes extremely easy. After sealing the container portion 29 and the substrate 30 and fixing the positions of the external terminals 27, the connecting portions between the external terminals 27 and the frame 28 are cut at the positions indicated by the dashed-dotted lines in FIG.
If removed, each external terminal 27 can be made electrically independent.

[Effects of the Invention] The EL panel of the present invention has a structure in which the external terminal hermetically penetrates the sealed portion between the substrate and the container, and contacts and conducts with the electrode end of the EL element inside the container. There is. Therefore, according to the present invention, there are the following effects.

(1) Al1. Since the electrodes of the EL elements made of ITO or the like do not corrode and have excellent moisture-proofing effects, a highly reliable EL panel with a long life can be realized.

(2) The electrode of the EL element made of a thin film such as Al tTo is not directly drawn out of the container, but the external terminal that contacts the electrode is drawn out of the container to apply a signal to the EL element. This makes it easier to connect to external circuits than in the past, and the mechanical strength of the connection area is also increased, improving reliability.

(3) Since an external terminal can be used as a spacer between the substrate and the container, the shape of the container may be a simple flat plate.

[Brief explanation of the drawing]

1 to 3 are cross-sectional views showing the EL panels of the first to third embodiments of the present invention, respectively, and FIG. 4 is the EL panel of the first embodiment of the present invention.
FIG. 5 is an enlarged view of the external terminals of the L panel before assembly, FIG. 5 is an enlarged view of the external terminals of the EL panel of the second embodiment before assembly, and FIG. 6 is an enlarged view of the EL panel of the first embodiment before assembly. FIG. 7 is a cross-sectional view of the container section before assembly in the EL panel of the second embodiment, FIG. 8 is a schematic diagram showing the manufacturing process of the embodiment, and FIG. 1θ is a typical EL panel. FIG. 11 is a schematic cross-sectional view showing the structure of the panel, FIG. 11 is a cross-sectional view showing a conventional EL panel, and FIG. 12 is a schematic enlarged perspective view showing the portion of the external terminal in FIG. 11 extending out of the container. It is. 1, la, lb-electroluminescent display panel (EL panel),
2.-Electroluminescent device (EL device), 3.3a, 30-substrate, 4-transparent electrode that is the electrode of the electroluminescent device, 6-back electrode that is the electrode of the electroluminescent device, 8-low melting point solder glass, 7.7a. 11.29-container part, 9,12,14.27-external terminal, 10,13.15-container inner end. Patent applicant Norimitsu Nishimura, agent/patent attorney for Futaba Corporation. A No. 101' and Figure 11 Procedures Amendment (Method) Showa 6'! ,,4Pj19E

Claims (3)

[Claims] (1) In an electroluminescent display panel that obtains a display by airtightly sealing a container part around the periphery of a substrate on which an electroluminescent element is formed and applying a signal to the electroluminescent element via an external terminal, the external An electroluminescent display panel, wherein a terminal hermetically passes through a sealed portion between the substrate and the container, and an inner end of the terminal contacts an end of each electrode of the electroluminescent element. (2) The electroluminescent display panel according to claim 1, wherein the substrate and the container portion are sealed with low melting point solder glass. (3) The electroluminescent display panel according to claim 1 or 2, wherein the external terminal is formed from an alloy material containing Ni-Fe as a main component.