JP2003303677A - Self-luminous element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a self-luminous element such as an EL element or a PDP element with a high rate of light emission and improved visibility by diffusing and reflecting light of critical angle or larger against a light-taking-out face in a transparent substrate. <P>SOLUTION: With the self-luminous element provided with at least a luminous layer between electrodes consisting of a pair of positive electrode and negative electrode at least either of which is transparent or translucent with its light- emitting side supported by the transparent substrate, a partition wall for diffusing and reflecting light emitted at a larger angle than the critical angle from the luminous layer toward an interface of the transparent substrate and the outside is fitted inside the transparent substrate. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroluminescence (EL) element or a plasma display (PDP) which has a high light extraction efficiency (light emission rate) and improved visibility.
The present invention relates to a self-luminous element such as an element.

[0002]

2. Description of the Related Art Conventionally, in a self-luminous element such as an EL element or a PDP element, light emitted from its light emitting layer has little directivity and isotropically and uniformly emitted into a transparent substrate supporting it. To be done. Of the emitted light, light having a critical angle or more with respect to the light extraction surface (light output surface) is denoted by reference numeral 11 in FIG.
As shown in FIG. 5, total reflection occurs, and light cannot be extracted from the inside of the transparent substrate 20 to the outside. According to Snell's law of refraction, the critical angle of total reflection when emitted from the refractive index n into the air can be expressed by the following equation. n sin θ _c = 1 (1)

The light extraction efficiency η when the substrate 20 shown in FIG. 6 is made of general glass or transparent resin has a light extraction efficiency η of only about 20%, which is the largest factor limiting the external light emission efficiency (light emission rate). Has become. Japanese Unexamined Patent Publication (Kokai) No. 10-241856 discloses a method in which the surface of a glass substrate is roughened to scatter light emitted from an EL element light-emitting layer to improve the light emission rate. As a result, due to the scattering by the rough surface, a component of the scattered light having a critical angle or more is generated, which causes a loss in the light output rate.

[0004]

SUMMARY OF THE INVENTION The present invention diffuses, within a transparent substrate, light emitted from a light-emitting layer of a self-luminous element such as an EL element or a PDP element and having a critical angle or more with respect to a light extraction surface. An object of the present invention is to provide a self-luminous element such as an EL element or a PDP element that has a high light emission rate and improved visibility by being reflected.

[0005]

The above object can be achieved by the present invention described below. That is, the present invention is a self-luminous element having at least a light emitting layer between an electrode composed of a pair of an anode and a cathode, at least one of which is transparent or semitransparent, the light emitting side of which is a self-luminous element supported by a transparent substrate, wherein the transparent substrate There is provided a self-luminous element, characterized in that a partition for diffusing and reflecting light emitted from the light emitting layer at an angle larger than a critical angle with respect to an interface between the transparent substrate and the outside is provided in the transparent substrate.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the following preferred embodiments. FIG. 1 is a schematic sectional view of an element showing one embodiment of the present invention. As shown in FIG. 1, the self-luminous element of the present invention has at least a light emitting layer 22 between electrodes composed of a transparent anode 21 and an opaque or light reflecting cathode 23, and the light emitting side thereof is supported by a transparent substrate 20. In the self-luminous element, a partition wall 30 for diffusing and reflecting light emitted from the light emitting layer 22 at an angle larger than a critical angle with respect to the interface between the transparent substrate 20 and the outside is provided in the transparent substrate 20. I am trying. In the above, the anode and the cathode may be reversed, the cathode may be transparent, and the anode may be opaque or light reflective.

When the self-luminous element is driven, as shown in FIG. 2, among the light emitted from the transparent anode 21, the light 11 having an angle component equal to or larger than the critical angle is reflected by the partition wall 30 and the transparent substrate 20. Light 12 is emitted from the transparent substrate 20 as light 12 having an angle less than the critical angle at the interface with air. In this way, in order to reflect the light 12 on the partition wall, it is preferable that the partition wall surface has a light scattering property.

The height h of the partition wall 30 is set by the following equation (2), where the pitch of the pixels (partition wall) is d.
The angle conversion can be performed by causing the light 11 having an angle component equal to or more than the critical angle of the emitted light to enter the partition wall. For example, from the equation (2), when the pitch (d) is 76 μm in the transparent substrate 20 having a refractive index of 1.5, the height (h) of the partition wall is preferably 85 μm or more. By increasing h, the directivity of the emitted light in the front direction can be improved. Even if h does not satisfy the formula (2), the effect of improving the light emission rate can be expected. Therefore, even for a self-luminous element having a relatively wide light emitting area for displaying a fixed pattern, characters, etc. The light output rate can be improved by providing the partition wall 30.

The partition wall 30 in the self-luminous element of the present invention.
Is preferably white. From this, a light-shielding film of a color filter for a liquid crystal display is disclosed in Japanese Patent Application Laid-Open No. HEI11
As disclosed in Japanese Patent Publication No. 2771755, when the self-luminous element is used for a white-based background color, the partition wall 3
The 0 color does not deteriorate the visibility of the displayed image. The material of the partition wall 30 is obtained by pressing powder of metal oxide or metal compound such as barium sulfide, magnesium oxide, aluminum oxide, titanium oxide, etc., which is white and has high reflectance, or these powders are dispersed in a resin. It can be used for things.

In the embodiment shown in FIG. 3, the partition wall 30 is used.
Is an example of penetrating the anode 21 and the light emitting layer 22 to reach the cathode 23. In this case, by using the partition wall 30 as an insulator, each pixel partitioned by the partition wall 30 can be provided with a light emitting layer having a different color of light emission to form a dot matrix type display. For that purpose, it is necessary to electrically isolate the electrode 21 between each pixel.
Therefore, the partition 30 needs to be an insulator, and by using such a partition 30, the manufacturing process of a dot matrix type display can be simplified.

FIG. 4 is a view taken along the line AA of FIG. 3, and illustrates that the partition walls 30 are provided in parallel stripes. As described above, the partition walls 30 and the light emitting layers 22 may have a stripe shape in which they are alternately arranged in the surface direction of the transparent substrate 20, or as shown in FIG. 5, the partition walls 30 may have a dot matrix shape. A full-color image can be displayed by forming the partition walls 30 in a dot matrix form and providing light emitting layers such as R, G, and B having different emission colors in each pixel.

As the material of the transparent substrate 20 used for the self-luminous element of the present invention, glass or a transparent resin such as acrylic resin, polycarbonate, polyester, polystyrene or the like can be used. In the case of forming the self-luminous element of the embodiment shown in FIG. 1, when the transparent substrate 20 is glass, the groove serving as a partition can be formed by mechanical cutting, etching by photolithography or the like. When the transparent substrate 20 is a film, sheet, or plate of the transparent resin as described above, a press die having a protrusion having the same shape as the partition 30 is used in addition to the above-described glass plate processing method. The groove to be the partition 30 can be continuously formed. From the viewpoint of ease of processing and productivity, it is preferable to use a transparent resin.

The partition wall 30 can be formed by filling the groove formed as described above with a white pigment having a high reflectance such as barium sulfide, magnesium oxide, aluminum oxide and titanium oxide. These white pigments may be dispersed in a solution containing a resin and filled in a groove with a blade or the like, or a paste in which the white pigment is dispersed in a thermosetting resin, an ultraviolet ray or an electron beam curable resin. It is also possible to fill the groove with a blade or the like and cure the resin to form a partition wall. Furthermore, after the above-mentioned filling, it is also preferable to thinly coat and cure any one of the above-mentioned clear coatings on the surface to improve the surface smoothness.

Next, the anode 21, the light emitting layer 22, the cathode 23 and the supporting substrate 24 are laminated on the lower surface of the transparent substrate 20 in the drawing to obtain the self-luminous element of the present invention having the structure shown in FIG. To be The supporting substrate 2 in this case
No. 4 is not essential, but it is preferable to provide 4 in terms of durability of the device. The thickness of the support substrate 24 is not particularly limited, and the material thereof is a glass plate, a resin film or a sheet. The self-luminous element of the present invention is prepared by laminating the transparent substrate 20 on which the partition walls 30 are formed with an appropriate adhesive on an element substrate obtained by laminating the cathode 23, the light emitting layer 22 and the anode 21 on the supporting substrate 24 in advance. Can also be In the self-luminous element shown in FIG. 2, the light emission rate of the light emitted from the light emitting layer 22 from the transparent substrate 20 is improved as described above.

Further, in the case of the self-luminous element of the present invention of the embodiment shown in FIG. 3, the cathode 23 formed on the support substrate 24.
The partition wall 30 can be formed by applying a paste in which a white pigment as described above is dispersed in a photosensitive resin to form a photosensitive layer, and patterning the photosensitive layer by a photolithography method. The partition wall can also be formed by, for example, a silk screen printing method. The width, height, interval, and other configurations of the partition wall may be the same as those in the embodiment shown in FIG.

After that, a light emitting layer 22 and a transparent electrode 21 are sequentially formed in a region defined by the partition wall 30, and a thermosetting resin, an ultraviolet ray or electron beam curable transparent coating material is applied and cured thereon. As a result, the transparent substrate 20 is formed and the self-luminous element of the present invention is obtained. In FIG. 3, after the partition walls are formed, glass or the transparent resin as described above is similarly filled between the partition walls, and then a glass plate, a resin sheet (film), or the like is laminated on the surface of the partition walls. A light emitting device is obtained. In the self-luminous element shown in FIG. 3, the light emission rate of the light emitted from the light emitting layer 22 from the transparent substrate 20 is improved as described above.

Examples of the self-luminous element of the present invention include EL elements and PDP elements, and EL elements are particularly useful. An example of an EL element will be described below. This will be described with reference to FIG. FIG. 1 is a partially enlarged sectional view of an EL display device as an example of the present invention. Acrylic substrate as the transparent substrate 20 (Sumitex Chemical, Sumipex, refractive index 1.49)
Was used, and a photopolymerizable acrylic monomer was slit-coated on this by a predetermined thickness. In this example, the total thickness of the substrate after curing was 0.5 mm. Next, in order to provide the partition walls 30, a mold which has been subjected to mold release treatment was pressed against the substrate, and a predetermined amount of ultraviolet rays was irradiated from the acrylic substrate side. After the curing was completed, the mold was peeled off to obtain a substrate having stripe-shaped grooves. Here, the dimensions of the substrate were designed and manufactured as follows. Total thickness of substrate = 0.5 mm Groove depth = 0.08 mm Groove width = 0.051 mm Groove pitch = 0.076 mm

Next, white pigment powder (titanium oxide) is enclosed in the groove, and in order to ensure the enclosure, an acrylic monomer is dropped into the groove filled with the white pigment, and a thin film is formed on the entire surface by spin coating. It was formed and subsequently cured by UV light. In addition to this, the thin film layer formation also has an effect of facilitating the EL layer formation process.

Then, on the substrate 20, E
The L layer was formed. The ITO transparent electrode 21 was sputtered.
The light emitting layer is made of a light emitting organic material Alq ₃ [tris (8-hydroxyquinol
ine) aluminium] and hole injection layer TPD [N, N'-diphenyl-N,
N'-bis (3-methyl-phenyl) -1,1-diphenyl-4,4'-diamine]
Were laminated. ITO was used as the transparent anode 21, and Mg-Ag alloy was used as the light-reflective cathode 23. TPD and IT
The stacking order was such that O was in contact.

The ITO 21 was 150 nm thick, and TPD purified by a sublimation purifying apparatus sufficiently preheated under high vacuum was loaded on a tungsten board to form a 50 nm film by a resistance heating method. Then, sublimated and purified Alq ₃ was loaded on the quartz board and a 30 nm film was formed by a resistance heating method. Finally, the thickness of the Mg-Ag alloy (Mg: Ag = 10: 1) is 15
It is vapor-deposited so as to have a thickness of 0 nm, Ag is vapor-deposited thereon as a protective layer so as to have a thickness of 200 nm, and finally, it is sealed with a separately prepared glass plate 24 and a UV-curing sealing material, and the The panel section was obtained. The EL display device of the present invention was completed by connecting a controller and a power supply circuit to this EL display device.

Subsequently, the power supply circuit of this EL display device was operated to light up the display, and a brightness measuring device (Topcon BM-7) was used in order to confirm the improvement in brightness. As a result of the measurement,
It has been confirmed that the light emission rate of EL emission is improved by about 20% as compared with a display device in which an equivalent EL layer pattern is formed on a general substrate having the same refractive index layer. This is because the EL light radiated in the substrate 20 cannot be extracted by being totally reflected from the vertical direction from 41.8 degrees beyond the critical angle in the case of a normal substrate, whereas in the present invention, the partition wall 30 is formed. Therefore, it is considered that the radiated light has a critical angle lying by that amount, and that radiated light is emitted without being totally reflected.

[0022]

According to the present invention as described above, light emitted from a light emitting layer of a self-luminous element such as an EL element or a PDP element and having a critical angle or more with respect to a light extraction surface is transmitted within a transparent substrate. It is possible to provide a self-luminous element such as an EL element or a PDP element having a high light output rate and improved visibility by diffuse reflection.

[Brief description of drawings]

FIG. 1 is a sectional view of a self-luminous element as an example of the present invention.

FIG. 2 is a diagram for explaining the function of the self-luminous element of FIG.

FIG. 3 is a diagram illustrating a function of a self-luminous element of another example of the present invention.

FIG. 4 is a diagram illustrating an example of a partition wall arrangement.

FIG. 5 is a diagram illustrating another example of the partition wall arrangement.

FIG. 6 is a sectional view illustrating a conventional self-luminous element.

[Explanation of symbols]

10: transmitted light 11: Totally reflected light 12: Diffuse reflected light 20: Transparent substrate 21: Anode 22: Light emitting layer 23: cathode 24: Support substrate 30: Partition wall

Claims (4)

[Claims] 1. A self-luminous element having at least a light emitting layer between an electrode composed of a pair of an anode and a cathode, at least one of which is transparent or semi-transparent, the light emitting side of which is supported by a transparent substrate. A self-luminous element, wherein a partition for diffusing and reflecting light emitted from the light emitting layer at an angle larger than a critical angle with respect to an interface with the outside is provided in the transparent substrate. 2. The self-luminous element according to claim 1, wherein the partition wall is white. 3. The self-luminous element according to claim 1, wherein the partition wall is an insulator. 4. The self-luminous element according to claim 1, which is an electroluminescence element.