JPH1140349A - El panel light emission and el light emitting display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To give a brightness contrast easily between a pattern and a background, or pattern components by layering a plurality of light emitting parts which is independent of each other on a common back surface electrode, and applying voltage between the respective light emitting parts. SOLUTION: Negligence of the effect of the impedance of a wiring and a capacitor would bring about a state where two capacitors whose electrode-to- electrode spacing is even are connected in series, therefore, the total value of voltages V1 , V2 for generating the electric fields E1 , E2 of the respective capacitors meet applied voltage V. The areas of regions 4a, 4b are taken as S1 , S2 , and average dielectric constants between the regions 4a, 4b and back surface electrodes 1 are taken as ε1 , ε2 respectively, a ratio of E1 to E2 follows E1 :E2 =ε2 S2 :ε1 S1 . Therefore, if the dielectric constants ε1 , ε2 are even to each other, the electric field is inversely proportional to the areas S1 , S2 of the regions 4a, 4b, by which brightness contrast which meets the inverse number of an area ratio is generated, so that the portion of a small area emits brighter light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting method for an EL panel and an EL light emitting display device using the method, and more particularly to a light emitting method and a display device for an EL panel provided with a luminance contrast.

[0002]

2. Description of the Related Art Electroluminescence (EL)
An inescence light-emitting panel is a thin light-emitting element in which an insulating layer, a light-emitting layer, a transparent electrode layer, and a protective layer provided as necessary are sequentially laminated on a back electrode. By applying a high-frequency voltage between the back electrode and the transparent electrode layer, the light emitting layer is excited to emit light. This EL light-emitting panel has been used for a backlight of a liquid crystal display or the like because of its easy weight reduction, low power consumption, and uniform surface light emission. Attention has been paid to the fact that they are small and excellent in stability, and attempts have been made to provide a pattern display function and use it for sign boards such as traffic signs.

For example, a mask (light-shielding sheet) is provided on the front of the panel to display a predetermined pattern (Japanese Patent Application Laid-Open No. 7-152334), or the entire display panel or its light emitting layer is formed into a predetermined pattern. Forming device (JP-A-6-20256
No. 7, JP-A-6-231885, etc.) are known. However, in such an apparatus, only the entire pattern is displayed uniformly and brightly, and it is difficult to display various patterns with one apparatus. Further, it is impossible to obtain a display panel in which a sign pattern having different brightness appears on a single panel in appearance.

An apparatus has been proposed in which electrode elements of an EL panel are formed in a predetermined pattern so that each element (characters, figures, etc.) of the pattern can be individually controlled (Japanese Patent Laid-Open No. 6-13180). Since both the pattern component and the background emit light at the same luminance, it is not possible to distinguish and recognize a set of patterns, and there is a problem in visibility such that the pattern is buried in the background. A method has also been proposed in which a transparent electrode or a back electrode of an EL panel is etched or coated to partially change the distance between the electrodes, thereby forming a difference in electric field strength to impart a luminance contrast (Japanese Patent Application Laid-Open No. Hei 6-1994). No. 203956). However, in this method, since the brightness continuously changes at the edge of the etched portion or the coated portion, it is difficult to display a clear pattern. Further, there is a limit to the adjustment of the electric field intensity by etching or coating, and the process is complicated.

[0005]

SUMMARY OF THE INVENTION The present invention provides a highly visible EL light-emitting display device that can easily impart luminance contrast between a pattern and a background or between pattern components in a single EL panel. The purpose is to:

[0006]

That is, the present invention relates to a light emitting method for an EL panel having the following configuration. (1) In a light emitting method of an EL panel, in which a light emitting portion composed of a laminate of an insulating layer, a light emitting layer, and a transparent electrode is stacked on a back electrode, and a light emitting layer facing the transparent electrode to which a voltage is applied emits light, A light-emitting method comprising: laminating independent light-emitting portions on a common back electrode; and applying a voltage between the light-emitting portions to form a luminance contrast between the light-emitting portions.

Further, the present invention provides an EL having the following structure.
The present invention relates to a light emitting device. (2) E in which a light emitting portion composed of a laminate of an insulator layer, a light emitting layer, a transparent electrode layer and a transparent resin layer is laminated on a back electrode.
In an EL light-emitting display device having an L light-emitting panel and a control circuit for applying a voltage to the light-emitting portion, a plurality of mutually independent light-emitting portions are formed by dividing a transparent electrode of the light-emitting portion by a minute gap. An EL light-emitting display device, wherein each light-emitting portion is stacked on a common back electrode, and by applying a voltage between the light-emitting portions, a luminance contrast corresponding to the area ratio is formed.

The EL device of the present invention includes the following aspects. (3) The EL light-emitting display device according to (2), wherein the light-emitting layer is obtained by dispersing a phosphor in an organic resin. (4) The light-emitting layer contains a phosphor or activator of a different luminescent color or further contains a fluorescent pigment of a different luminescent color according to the division pattern of each section, and displays a color-coded pattern. The EL light-emitting display device according to 2) or 3).

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a light emitting method of the present invention and an EL light emitting display device using the same will be described in detail with reference to the drawings. (I) Light Emitting Method FIG. 1 schematically shows an EL panel, and FIGS. 2 and 3 show a light emitting method according to the prior art and a method according to the present invention in comparison. The EL panel schematically shown in FIG. 1 is a thin light emitting element in which an insulator layer 2, a light emitting layer 3, and a transparent electrode layer 4 are sequentially laminated on a back electrode 1, and the insulator panel 2, the light emitting layer 3, and the A light emitting portion is formed by the laminate of the transparent electrode layers 4. The light emitting portion is divided into a plurality of independent light emitting portions by the transparent electrode 4 being partitioned by minute voids,
These light emitting portions are stacked on a common back electrode 1.
In the illustrated configuration example, the transparent electrode layer 4 is
It is divided into the above (two in the figure) areas 4a and 4b. Although the areas 4a and 4b are rectangular areas arranged in parallel in FIG. 1 for simplicity, characters and figures and a background are generally formed. Current collecting zones 7a and 7 are provided on the transparent electrode layers 4a and 4b.
b, a current collecting band 7c is provided on the back electrode 1, and terminals 8a to 8c are connected to the current collecting band 7c, respectively.

In a conventional transparent electrode split type EL panel,
As shown in FIG. 2, an AC voltage is applied between 8a and / or 8b and 8c. When a voltage is applied between 8a and 8c, only the portion of the light emitting layer 3 facing the region 4a emits light. If a voltage is applied between 8b and 8c, only the portion of the light emitting layer 3 facing 4b emits light. When a voltage is applied between 8a and 8b and 8c, each of the portions emits light. However, as is apparent from FIG. 2, since an equal voltage is applied to these portions, light is emitted with the same luminance.

On the other hand, in the light emitting method of the present invention, as shown in FIG. 3A, an AC voltage is applied between the terminals 8a and 8b.
That is, an AC voltage is applied between the divided regions of the transparent electrode. As a result, the back electrodes 1 to which no voltage is applied are set in the middle, and the regions 4a and 4b
AC electric fields E ₁ and E ₂ are respectively formed between the substrate and the back electrode 1 (FIG. 3B), and the light emitting layer 3 facing each region emits light.

If the effects of the impedances of the wiring and the capacitors are ignored, two capacitors having the same electrode spacing are connected in series, so that the voltage V for generating the electric fields E ₁ and E ₂ of each capacitor is obtained. ₁ ,
The total value of V ₂ matches the applied voltage V. In addition, the area 4a
Is S ₁ , the average dielectric constant between the region 4 a and the back electrode 1 is ε ₁ , the area of the region 4 b is S ₂ , and the average dielectric constant between the region 4 b and the back electrode 1 is ε ₂ Then, the ratio of E ₁ and E ₂ follows E ₁ : E ₂ = ε ₂ S ₂ : ε ₁ S ₁ . Therefore, when the dielectric constants ε ₁ and ε ₂ are equal, the electric field is equal to the area S of the regions 4a and 4b.
₁ , which is inversely proportional to S ₂ , and since the intensity of the electric field and the volatility are roughly in a proportional relationship, a brightness contrast corresponding to the area ratio, that is, according to the reciprocal of the area ratio is formed, and The part will emit light more brightly. S
_1: is not the ratio of S ₂ is particularly limited, the amount of energization because they are governed by part of the small area, S _1: luminous efficiency to be too small or too large a ratio of S ₂ is decreased. Usually 1: 2 to 1: 1
About 0 is preferable.

Although the transparent electrode is divided into two regions in the illustrated example, it may be divided into three or more regions. The division of the transparent electrode may be performed by providing a gap without interposing an insulator. In order to obtain a luminance contrast, the dielectric constants ε ₁ and ε ₂ may be changed by adjusting the materials of the light emitting layer and the insulating layer.

(II) EL Light Emitting Display Device FIG. 4 shows an example of the EL light emitting display device of the present invention. As shown in the figure, the EL light-emitting display device of the present invention has an EL panel 10
And a control circuit C for causing the panel to emit light in accordance with the above-described light emitting method, and a lead wire connecting these. The EL panel 10 is formed by laminating a light emitting portion composed of a laminate of an insulator layer, a light emitting layer, a transparent electrode layer, and a transparent resin layer on a back electrode, and the transparent electrode of the light emitting portion has a minute gap. , A plurality of mutually independent light-emitting portions are defined. Specifically, as shown in FIG. 5, a transparent electrode layer 14 is laminated on a transparent resin layer 16, and the transparent electrode layer 14 is divided into a predetermined pattern by minute voids 15, and current is collected in each region. Bands 17a to 17f and terminals 18a to 18f are provided, and a transparent electrode layer 14 is laminated on a laminate composed of the back electrode 11-the insulator layer 12-the light emitting layer 13 so as to face the light emitting layer 13. I have.

As shown in FIG. 5 and FIG. 8 which is a partially enlarged sectional view of FIG.
In the case where characters / codes are present in the (ground), the parts where each surface area comes into contact with the terminal drawn out from the other surface area are provided with an insulating material such as an insulating tape between them. Insulate. For example, in FIG. 5, the terminals 18a to 18a to 1
8e, rectangular transparent insulators 36a to 36e
Is provided. As shown in FIG. 8, normally, the transparent insulating tape 3 extends from the edge of the transparent electrode layer 14 to the current collecting zone 17a in the inner region (in FIG. 5, an arrow-shaped region).
6a is provided. Next, the terminal 18a is bonded to the current collector 17a and the insulating tape 36a, and then the light emitting layer 13 is laminated. The same applies to the terminals 18b to 18e. Thereby, the terminals 18a to 18e can be electrically connected only to the internal divided regions. Note that the transparent insulating tape 36a and the like may be attached to one side (the transparent electrode layer side) of the terminal 19, but in order to ensure insulation, the transparent insulating tape 36a may be slightly larger than the terminal 18a or the like on the transparent electrode layer. It is preferable that an insulating tape is attached widely.

The method of dividing the transparent electrode layer is not particularly limited as long as it can be divided by a minute gap. For example, the transparent electrode layer may be formed by cutting with a cutter blade or a tip of a needle. The cut may be formed by pressing the formed blade.

The material of the transparent resin layer 16 is not particularly limited as long as it is an organic polymer material which is transparent in a visible light region and has high insulating properties. For example, a polyester resin such as PET (polyethylene terephthalate) or PEN (polyethylene naphthalate), a plastic film, or a transparent glass having reduced flexibility can be used. The thickness of the transparent resin layer is not particularly limited, but usually may be about 2.5 to 150 μm. EL
The panel is preferably covered entirely with a moisture barrier film. Examples of the moisture-proof film include ethylene trifluoride chloride resin and its copolymer, fluorinated ethylene copolymer, vinylidene chloride resin and its copolymer, and the like.

In the example shown in FIG. 5, an insulating layer, a light emitting layer and a transparent electrode layer are sequentially laminated one by one on a back electrode.
Although the L panel is shown, some of these layers may be removed, the order may be changed, or a plurality of layers may be used, or other layers may be stacked as long as the light emission principle of the EL panel is adapted. For example, a moisture absorbing film is further laminated on the back electrode and the transparent resin layer. Nylon resin, PVA (polyvinyl alcohol), acrylamide resin or the like can be used as the moisture absorbing film.

The control circuit C is for applying a voltage between the sections of the transparent electrode layer 14 which are defined, and is connected to terminals drawn from the respective areas. In the example of FIG. 4, the transparent electrode layer 14 is divided into arrow-shaped regions 14 a to 14 e and a background region 14 f, but a pattern controlled between them, for example, an AC voltage is applied in the order shown in Table 1. I do. In Table 1, the + sign regions are coupled to each other, and a voltage is applied between the + sign regions. 0 indicates that no voltage is applied.

[0020]

[Table 1]

In Table 1, in the state I, an arrow area 14a
To 14e are combined as a whole, and a voltage is applied to the background region 14f. The luminance ratio is obtained by defining the area of each region as Sa,
Assuming that Sb, Sc, Sd, Se and Sf, approximately Sf:
(Sa + Sb + Sc + Sd + Se). Therefore, FIG.
As shown in the figure, the arrow appears to emerge even brighter on the bright surface as a whole. In state II, arrow regions 14a to 14a
Although 14e emits light, the brightness ratio between the area 14e and the other arrow area is approximately (Sa + Sb + Sc + Sd) because the 14e connected in series with the area 14a to 14d connected in parallel has an opposite charge. ): Se. That is, the area 14e appears to be brightly shining at almost four times the luminance of the other areas. In the state III to VI, the arrow region brighter than the others sequentially transitions from 14d to 14a. As a whole, in the row of arrows, one arrow that shines with brightness contrast with the other arrows appears to move in the moving direction while changing places, and sign display with extremely high visibility is realized. Such a control circuit can be constituted by conventional means, for example, a combination of an appropriate logic circuit and a timer circuit. It is also possible to draw a terminal from the back electrode and display in combination with a conventional light emitting method.

[0022]

Embodiment 1 FIG. 7 shows an example of a light emitting display device according to the present invention. On a back electrode 21 (20 cm × 100 cm) made of Al foil, barium titanate powder and a high dielectric binder (cyanoethyl furran) were mixed with DMF.
An ink dissolved in (N, N-dimethylformamide) was printed by a blade method and dried to form an insulator layer 22. On the insulator layer 22, an ink in which a high insulator binder and a ZnS phosphor (doped with Cu and Cl) were dissolved in an organic solvent was printed by a blade method, and dried to form a light emitting layer 23. On the other hand, a rectangular cut 25 was made with a stainless steel cutter from the ITO transparent electrode side into a commercially available PET film 26 on which an ITO film 24 (thickness: about 0.1 μm) was formed by sputtering.
a (arrow), 24b (character E), 24c (character X), 24d
(Character I), 24e (character T) and background area 24f were formed. Each of the regions 24a to 24f has a part close to the edge of the film, but Ag paste is screen-printed in the close part to form the current collecting bands 27a to 27f, and the terminals 28a to 28f made of copper foil are formed. In order to insulate 28f from the ITO electrode on the back surface, this portion was insulated with a transparent insulating tape (not shown) and then adhered to each current collector band. Further, a terminal 28g was bonded to the back electrode. The laminated body composed of the back electrode, the insulator layer, and the light emitting layer formed as described above is laminated with a laminator such that the transparent electrode layer 24 and the light emitting layer 23 face each other, and a nylon material is formed on the rear electrode and the transparent electrode layer. The transparent moisture-absorbing film was covered, and the whole laminate was sealed with a transparent moisture-proof film, ethylene trifluoride chloride resin, using a laminator to produce a light-emitting panel. The manufactured panel is a single panel in which the separation line by the cut 25 cannot be visually identified.

(A) According to a conventional light emitting method, when an AC voltage of 100 V and 400 Hz is applied between the terminal 28g of the back electrode of the light emitting panel and the terminals 28a to 28e of the character / symbol display area, the character / symbol is obtained. Only emitted light at about 60 cd / m ² . When the background area terminal 28f was further connected to the character / symbol terminal side and the AC voltage was applied between 28a-28f and 28g, the entire EL panel emitted light, and neither characters nor symbols could be recognized at all. (B) On the other hand, when an AC voltage of 100 V and 400 Hz was applied between the terminals 28a to 28e of the character / symbol display area of the light emitting panel and the background area terminal 28f according to the light emitting method of the present invention, the background was 10 cd / in m ² characters and symbols is 33cd /
It emits light at m ² , enabling full-screen display with brightness contrast. When an AC voltage of 100 V and 400 Hz was applied between the symbol display area terminal 28a and the character display area terminals 28b to 28e, the arrow symbol was 39 cd / m ² and the character string “EXIT” was 15 cd / m ^2. , And a display with a brightness contrast became possible. The background area did not emit light. (C) When a control circuit that sequentially transitions the connection state every few seconds is used, although it is apparently a single panel,
From a state where the symbols and the like are not visible at all, a pattern in which the characters / symbols and the background are distinguished by the brightness contrast is displayed, and then a sign display with high recognizability in which the arrow symbols have high brightness and are emphasized is obtained.

Example 2 An EL light-emitting panel was manufactured by using rhodamine 6G type (yellow type) and rhodamine B type (red type) as fluorescent pigments and separately applying the sign / character portion and the background phosphor layer. This panel was able to identify the display even when the power was not supplied, and showed a highly visible display having a difference in color tone in addition to contrast when a voltage was applied.

[0025]

According to the light-emitting method of the present invention, light-emission with luminance contrast can be easily generated, so that information visibility on a signboard or the like can be improved. In addition, since a luminance contrast is generated by a combination of regions to which a voltage is applied, a special process is not required for manufacturing an EL panel, and there is a high degree of freedom in combining regions having a luminance ratio and a contrast using a conventional EL panel. Display becomes possible. As a result, various display patterns in which the emphasized portion is changed as necessary can be realized. Further, a light-emitting display device in which a transparent electrode is divided by cutting can be used as a sheet in which a sign cannot be identified at all without applying a voltage, and therefore, besides information display use, for example, luminance contrast, gradation, etc. It can also be used as a wall material or the like to which decorative properties are added.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing the structure of an EL light-emitting panel.

FIG. 2 is a schematic cross-sectional view showing a connection state of a conventional EL panel light emitting method.

3A is a schematic cross-sectional view showing a connection state of an EL panel light emitting method according to the present invention, and FIG.

FIG. 4 is a conceptual diagram showing the entire configuration of an EL light emitting display device according to the present invention.

FIG. 5 is an assembly view showing a laminated structure of the EL panel of FIG. 4;

FIG. 6 is an explanatory diagram showing a situation when the EL panel of FIG. 4 is used.

FIG. 7 is an assembly view showing another EL light emitting display device according to the present invention.

8 is a partial cross-sectional view showing the vicinity of a terminal 18a in FIG.

[Explanation of symbols]

1-back electrode, 2-insulator layer, 3-light-emitting layer, 4-transparent electrode layer, 4a, 4b area on transparent electrode, 5-insulator, 7
a-7c-collecting band, 8a-8c-terminal, 10-EL panel, 11-back electrode, 12-insulator layer, 13-light emitting layer,
14-transparent electrode layer, 14a-14f-area on transparent electrode, 15-cut, 16-transparent resin layer, 17a-17
f-collecting band, 18a-18f-terminal, 21-back electrode,
22-insulator layer, 23-light-emitting layer, 24-transparent electrode layer, 2
4a-24f-area on transparent electrode, 25-cut, 2
6-PET film, 27a-27f-collecting band, 28a
-28g-terminal, 36a-36e: transparent insulating tape

Claims (4)

[Claims] 1. A light-emitting method for an EL panel, comprising: a light-emitting portion comprising a laminate of an insulating layer, a light-emitting layer, and a transparent electrode, stacked on a back electrode, and causing the light-emitting layer facing the transparent electrode to which a voltage is applied to emit light. A light-emitting method comprising: laminating the independent light-emitting portions on a common back electrode; and applying a voltage between the light-emitting portions to form a luminance contrast between the light-emitting portions. 2. An EL light-emitting panel in which a light-emitting portion composed of a laminate of an insulator layer, a light-emitting layer, a transparent electrode layer, and a transparent resin layer is laminated on a back electrode, and a control circuit for applying a voltage to the light-emitting portion. In the EL light-emitting display device, the transparent electrode of the light-emitting portion is partitioned by minute voids to form a plurality of independent light-emitting portions, and each of the light-emitting portions is stacked on a common back electrode. An EL light-emitting display device, wherein a luminance contrast corresponding to an area ratio is formed by applying a voltage between light-emitting portions. 3. The EL light emitting display according to claim 2, wherein the light emitting layer is formed by dispersing a phosphor in an organic resin. 4. The light-emitting layer contains phosphors or activators of different emission colors according to the division pattern of each section,
The EL light-emitting display device according to claim 2, wherein a color-coded pattern further comprising fluorescent pigments of different emission colors is displayed.