JP2006059543A - El device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an EL device capable of efficiently emitting light generated in a light emitting layer of an EL element, and capable of effectively utilizing light emitted from the EL element, and the EL device to deflect the light emitted from the EL element into a prescribed direction. <P>SOLUTION: The EL device is provided with a plate shaped first electrode 4, a plate shaped transparent second electrode 6 installed at one face of a transparent substrate 12, plate shaped light emitting parts 8, 10 arranged between the first and second electrodes, and a light deflecting element 16 which is installed at the other face 12a of the transparent substrate, and in which the light emitted from the light emitting parts is deflected toward the normal direction of the other face. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an EL device, and more particularly to an EL device that can efficiently emit light generated by an EL element.

  An EL element using EL (Electro Luminescence) is known as one of displays for displaying images and the like. This EL element has a sandwich structure in which a thin film-like light emitting layer is sandwiched between two plate-like electrodes, a voltage is applied to the electrode to cause the light emitting layer to emit light, and light is transmitted through one electrode formed of a transparent material. Is a structure that leads to the outside. It is classified into organic EL and inorganic EL depending on the kind of the substance containing the light emitting layer.

  An example of the basic structure of the organic EL element will be described with reference to FIG. As shown in FIG. 6, the organic EL element 50 includes a plate-like metal cathode 52 made of MgAg alloy or the like and a plate-like transparent anode 54 made of indium / tin oxide or the like. The transparent anode 54 is provided on one surface 56 a of the glass substrate 56. Further, a hole transport layer 58 made of a diamine compound or the like and a light emitting layer 60 containing a light emitter such as a quinolinol aluminum complex are laminated between the metal cathode 52 and the transparent anode 54.

In the organic EL element having such a configuration, when a DC voltage is applied to the metal cathode 52 and the transparent anode 54 by the DC power source 62, holes injected from the transparent anode 54 into the hole transport layer 58 enter the light emitting layer 60. Then, electrons injected from the metal cathode 52 diffuse and move in the light emitting layer 60. As a result, holes and electrons are recombined and electrically neutralized in the light emitting layer 60, and the molecules of the light emitter of the light emitting layer 60 are changed from the ground state to the excited state. The light emitting layer 60 emits light by the energy released when the molecules of the phosphor in the excited state return to the ground state. And the light which permeate | transmitted the transparent electrode 54 and was radiate | emitted from the other surface 56b (light emission surface) of the glass substrate 56 is utilized for an image display.
The present invention has been developed based on such publicly known technology.

  In the EL element having the above-described configuration, image display or the like is performed using light generated in the light emitting layer 60 and emitted from the other surface (emission surface) 56 b of the glass substrate 56. However, most of the light that enters the glass substrate 56 and reaches the emission surface 56b is totally reflected at the boundary surface between the emission surface 56b and the outer air layer, and is emitted from the end surfaces 56c and 56d of the glass substrate 56. There is a problem that the light generated in the light emitting layer cannot be effectively extracted from the emission surface.

  Further, the light emitted from the emission surface 56b also has a problem that the front luminance of the EL element is low because the component emitted in the direction orthogonal to the emission surface 56b is low, and the emitted light cannot be effectively used.

  The present invention has been made to solve the above-described problems of the prior art, and can efficiently emit the light generated in the light emitting layer of the EL element, and the light emitted from the EL element is effective. An object of the present invention is to provide an EL device that can be used for the above.

  According to the present invention, the plate-like first electrode, the plate-like transparent second electrode provided on one surface of the transparent substrate, and the first and second electrodes are disposed. An EL element comprising a plate-like light emitting part; and an optical deflecting element provided on the other surface of the transparent substrate for deflecting light emitted from the light emitting part in the normal direction of the other surface; There is provided an EL device characterized by comprising:

In the present invention configured as described above, since the light deflection element is provided on the other surface serving as the emission surface of the transparent substrate, total reflection on the other surface is less likely to occur, and more light is emitted. The light exits from the other surface.
Further, since the light emitted from the other surface of the transparent substrate is deflected toward the normal direction of the other surface by the light deflection element, the emitted light is effectively used and the front luminance of the device is improved. Furthermore, since light can be extracted efficiently, the driving power is reduced and the life of the EL device can be extended.

According to another preferred aspect of the present invention, at least one surface of the end surface of the transparent substrate is covered with a reflective material.
According to such a configuration, light emitted from the end face of the transparent substrate is reduced, so that light from the EL element can be efficiently extracted.

According to another preferred aspect of the present invention, the light deflection element includes a plurality of prisms.
According to another preferred aspect of the present invention, the prism is disposed so as to taper toward the other surface of the transparent substrate, and totally reflects the light from the light emitting unit to thereby provide the other surface of the transparent substrate. The surface is deflected toward the normal direction.
According to another preferred aspect of the present invention, the prism is disposed so as to expand toward the other surface of the transparent substrate, and refracts light from the light emitting portion to cause the other surface of the transparent substrate to be refracted. The surface is deflected toward the normal direction.

According to another preferred aspect of the present invention, the prism is a trapezoidal prism.
According to another preferred aspect of the present invention, the prism is a triangular prism.

According to another preferred aspect of the present invention, the light deflection element includes a plurality of cylindrical lenses.
According to another preferred aspect of the present invention, the cylindrical lens is disposed so as to be convex toward the other surface of the transparent substrate, and totally reflects the light from the light emitting portion to A surface that deflects toward the normal direction of the other surface is provided.

  According to another preferred aspect of the present invention, the cylindrical lens is disposed so as to be convex in the direction opposite to the other surface of the transparent substrate, and refracts light from the light emitting portion to thereby transmit the transparent lens. A surface that deflects toward the normal direction of the other surface of the substrate is provided.

According to another preferred aspect of the present invention, the light deflection element includes a large number of dots or recesses formed of a curved surface.
According to another preferred aspect of the present invention, the curved surface has an inclination angle of 30 degrees or more with respect to the other surface of the transparent substrate.

According to another preferred aspect of the present invention, the optical deflection element has optical anisotropy.
According to another preferred aspect of the present invention, the pitch of the plurality of prisms is 15 μm or less.
According to another preferred aspect of the present invention, the light deflection element is made of a UV curable resin.

  According to the present invention, there is provided an EL device capable of efficiently emitting light generated in the light emitting layer of the EL element and effectively using the light emitted from the EL element.

Hereinafter, an EL device according to an embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view schematically showing the structure of the EL device 1 according to the first embodiment of the present invention. As shown in FIG. 1, the EL device 1 is a rectangular plate-shaped organic EL device including an organic EL element 2. The organic EL element 2 includes a plate-like metal cathode 4 made of a metal such as MgAg alloy, a plate-like transparent anode 6 made of a transparent material such as indium / tin oxide, and the metal cathode 4 and the transparent anode 6. And a light-emitting layer 10 including a quinolinol aluminum complex and the like, and a hole transport layer 8 including a diamine compound and the like laminated therebetween.

  The transparent anode 6 is disposed so as to be optically in close contact with one surface 12 a of the glass transparent substrate 12 constituting the organic EL element 2. Here, “optically close” refers to a state where objects having optical transparency are in close contact with each other without forming an air layer therebetween.

  Each end face 2 c, 2 d of the organic EL element 2 is covered with a metal reflection film 14. Therefore, in the EL device 1 of the present embodiment, the light that is generated in the light emitting layer 10 and is incident on the transparent substrate 12 from the one surface 12a of the transparent substrate 12 is not emitted from the end surface of the transparent substrate 12, but the other side of the transparent substrate 12 The light exits only from the surface (exiting surface) 12b.

  A plurality of prisms 16 constituting an optical deflection element that deflects light emitted from the emission surface 12b toward the normal direction of the emission surface 12b are disposed on the emission surface 12b of the transparent substrate 12. In the present embodiment, as shown in FIG. 1, the prism 16 is a columnar prism having an isosceles trapezoidal cross section, and is arranged in parallel so that the upper base (short side) 16a is optically in close contact with the emission surface 12b. Has been. The prism 16 is formed of a transparent resin (for example, a UV curable resin) having a refractive index close to that of the transparent substrate 12.

  The prism 16 totally reflects light incident on the transparent substrate 12 from the exit surface 12b and reaching the slopes 16c and 16d from the exit surface 12b, and deflects in the normal direction of the exit surface 12b of the transparent substrate 12 to exit the exit surface. 16b is made to emit. Therefore, the light deflection element constituted by the prism 16 has optical anisotropy.

  Further, the pitch P between the adjacent prisms 12 is preferably set to 15 μm or less, and more preferably set to 10 μm or less.

  Furthermore, a DC power source 18 is connected to the organic EL element 2 so that a DC voltage can be applied to the metal cathode 4 and the transparent anode 6.

  When a DC voltage is applied to the metal cathode 4 and the transparent anode 6 by the DC power source 18, the light emitting layer 10 emits light. The light generated in the light emitting layer 10 passes through the transparent anode 6 and enters the transparent substrate 12 from the upper surface 12 a of the transparent substrate 12. As described above, in the present embodiment, since the back surface of the organic EL element 2 is covered with the metal cathode 4 and the end surface is covered with the metal reflection film 14, the light emitted from the light emitting layer 10 is emitted from the transparent substrate 12. Only 12b can be emitted.

  Since the prism 16 having a trapezoidal cross section, which is an optical deflection element, is disposed in optical contact with the exit surface 12b, the critical angle of the exit surface 12b is large. As a result, in the EL device 1, light that is about to be emitted from the transparent substrate 12 through the emission surface 12b is less likely to cause total reflection at the emission surface 12b, and light generated by the organic EL element 2 is efficiently extracted from the emission surface 12b. It is.

Furthermore, since the prism 16 which is an optical deflection element deflects the emitted light toward the normal direction of the emission surface 12b, the front luminance of the EL device 1 is improved. As a result, it can be used as a highly efficient image display device (display) or a light source.
Furthermore, since the EL device 1 can efficiently extract light and increase the front luminance, the driving power can be reduced and the product life is extended.

  Next, an EL device according to a second embodiment of the invention will be described. FIG. 2 is a schematic sectional view similar to FIG. 1, showing an EL device 20 according to the second embodiment of the present invention. As shown in FIG. 2, the EL device 20 of the second embodiment basically has the same configuration as the EL device 1 of the first embodiment. Therefore, in FIG. 2, the same parts as those in FIG.

  As shown in FIG. 2, in the EL device 20 according to the second embodiment of the present invention, instead of the prism 16 of the EL device 1 of the first embodiment, a plurality of cylindrically shaped (flat spherical) cylindrical lenses. 22 is arranged in parallel on the emission surface 12b. The cylindrical lens 22 is formed of a transparent resin (for example, a UV curable resin) having a refractive index close to that of the transparent substrate 12.

  The cylindrical lens 22 is arranged in a convex shape toward the emission surface 12b so that the top portion is in optical contact with the emission surface 12b. Each cylindrical lens 22 has a curved side surface that totally reflects the light incident from the exit surface 12b by the curved surface 22a, deflects the light in the normal direction of the exit surface 12b, and emits the light from the exit surface 22b. It is configured. Therefore, the optical deflection element constituted by the cylindrical lens 22 has optical anisotropy.

  According to the EL device 20 according to the second embodiment of the present invention, since the cylindrical lens 22 is provided in optical close contact with the emission surface 12b of the transparent substrate 12, the critical angle of the emission surface 12b increases. As a result, in the EL device 20, light that is about to be emitted from the transparent substrate 12 through the emission surface 12b is less likely to cause total reflection at the emission surface 12b, and light generated by the organic EL element 2 is efficiently extracted from the emission surface 12b. It is.

Furthermore, since the cylindrical lens 22 which is an optical deflection element deflects the emitted light toward the normal direction of the emission surface 12b, the front luminance of the EL device 20 is improved. As a result, it can be used for a highly efficient image display device (display) or a light source.
Furthermore, since the EL device 20 can efficiently extract light and increase the front luminance, the driving power can be reduced and the product life is extended.

  Next, an EL device according to a third embodiment of the invention will be described. FIG. 3 is a schematic sectional view similar to FIG. 1, showing an EL device 24 according to a third embodiment of the present invention. As shown in FIG. 3, the EL device 24 according to the third embodiment has basically the same configuration as the EL device 1 according to the first embodiment. Therefore, in FIG. 2, the same parts as those in FIG.

  As shown in FIG. 3, in the EL device 24 according to the third embodiment of the present invention, the light deflection that deflects the light emitted from the emission surface 12 b toward the normal direction of the emission surface on the emission surface 12 b of the transparent substrate 12. A plurality of prisms 26 constituting the element are arranged. The prism 26 is a columnar prism having an isosceles trapezoidal cross section similar to that of the prism of the first embodiment. As shown in FIG. 3, in this embodiment, the prism 26 is a lower base of each prism 26. The (long side) 26a is arranged in parallel so as to be optically in close contact with the emission surface 12b. The pitch P of the adjacent prisms 26 is preferably set to 15 μm or less, and more preferably set to 10 μm or less. Also in this embodiment, the prism 26 is formed of a transparent resin (for example, a UV curable resin) having a refractive index close to that of the transparent substrate 12.

  The prism 26 refracts light that has entered the prism 26 from the exit surface 12b of the transparent substrate 12 and reached the inclined surfaces 26c and 26d, and deflects the light in the normal direction of the exit surface 12b of the transparent substrate 12, thereby exiting the exit surface 26b. And is configured to emit light. Therefore, the light deflection element constituted by the prism 26 has optical anisotropy.

  According to the EL device 24 according to the third embodiment of the present invention, since the prism 26 is attached in optical close contact with the emission surface 12b of the transparent substrate 12, the critical angle of the emission surface 12b is increased. As a result, in the EL device 20, light that is about to be emitted from the transparent substrate 12 through the emission surface 12b is less likely to cause total reflection at the emission surface 12b, and light generated by the organic EL element 2 is efficiently extracted from the emission surface 12b. It is.

Furthermore, since the prism 26 which is an optical deflection element deflects the emitted light toward the normal direction of the emission surface 12b, the front luminance of the EL device 24 is improved. As a result, it can be used for a highly efficient image display device (display) or a light source.
Furthermore, since the EL device 24 can efficiently extract light and increase the front luminance, the driving power can be reduced and the product life can be extended.

  Next, an EL device according to a fourth embodiment of the invention will be described. FIG. 4 is a schematic sectional view similar to FIG. 1, showing an EL device 28 according to a fourth embodiment of the present invention. As shown in FIG. 4, the EL device 28 of the fourth embodiment has basically the same configuration as the EL device 1 of the first embodiment. Therefore, in FIG. 4, the same parts as those in FIG.

  As shown in FIG. 4, columnar prisms 30 having a triangular cross section are arranged in parallel on the emission surface 12 b of the transparent substrate 12 of the EL device 28 instead of the prism 26 having a trapezoidal cross section in the third embodiment. Has been placed. The prism 30 is also formed of a transparent resin (for example, a UV curable resin) having a refractive index close to that of the transparent substrate 12.

  Similar to the trapezoidal prism 26, the triangular prism 30 also constitutes an optical deflection element that deflects the light emitted from the emission surface 12b in the normal direction of the emission surface. In the present embodiment, the prisms 30 are arranged in parallel so that the base 30a is in optical contact with the emission surface 12b. The prism 30 is configured to refract the light that has entered the prism 30 and reached the inclined surfaces 30 b and 30 c and deflects the light toward the normal direction of the emission surface 12 b of the transparent substrate 12. Therefore, the light deflection element constituted by the prism 30 has optical anisotropy.

  The pitch P between adjacent prisms 30 is preferably set to 15 μm or less, and more preferably set to 10 μm or less.

  Also in the EL device 28 having such a configuration, the same effects as the EL devices of the first to third embodiments can be obtained.

  Next, an EL device according to a fifth embodiment of the invention will be described. FIG. 5 is a schematic sectional view similar to FIG. 1, showing an EL device 32 according to a fifth embodiment of the present invention. As shown in FIG. 5, the EL device 32 of the fifth embodiment has basically the same configuration as the EL device 1 of the first embodiment. Therefore, in FIG. 5, the same parts as those in FIG.

  As shown in FIG. 5, in the EL device 32 according to the fifth embodiment of the present invention, instead of the prism 16 of the EL device 1 of the first embodiment, a plurality of cylindrically shaped (flat spherical) cylindrical lenses. 34 is arranged in parallel on the emission surface 12b. The cylindrical lens 34 is also formed of a transparent resin (for example, a UV curable resin) having a refractive index close to that of the transparent substrate 12.

  The cylindrical lens 34 is disposed such that the bottom surface 34a is in optical contact with the emission surface 12b and is convex in the opposite direction to the emission surface 12b. Each cylindrical lens 34 is configured such that its curved side surface is incident on the exit surface 12b, refracts the light exiting from this side surface, and is deflected toward the normal direction of the exit surface 12b. Therefore, the light deflection element constituted by the cylindrical lens 34 has optical anisotropy.

  The convex side surface of the cylindrical lens 34 is preferably set so that the angle formed with the emission surface 12b of the transparent substrate 12 is 30 ° or more, more preferably 40 ° or more, and most preferably 50 ° or more. It is good to be.

  Also in the EL device 32 having such a configuration, the same operational effects as those of the EL devices of the first to third embodiments can be obtained.

  Further, instead of the prism and the cylindrical lens of the above embodiment, a substantially hemispherical shape, or a substantially semi-elliptical spherical shape having a large number of dots or a plurality of concave portions formed continuously or discretely, or directly A transparent sheet having such dots and recesses formed on the surface is optically adhered to the exit surface, and the total reflection on the exit surface is suppressed by the dots and recesses, and the light emitted from the exit surface is emitted from the transparent substrate. It may be configured to deflect in the normal direction. At this time, it is preferable that the inclination angle of the curved surface constituting the dot or the recess has an inclination angle of 30 ° or more with respect to the emission surface of the transparent substrate. Such dots and recesses can be formed by die transfer by etching treatment such as hydrofluoric acid treatment or solvent treatment, hot pressing, injection molding, extrusion molding or the like.

  The present invention is not limited to the above-described embodiment, and various changes and modifications can be made within the scope of the technical idea described in the claims.

  In the above-described embodiment, the prism has a columnar shape such as a triangular prism or a trapezoidal column. However, a large number of triangular pyramids, square pyramids, and truncated trapezoidal prisms are randomly or regularly arranged on the exit surface of the transparent substrate. Alternatively, the configuration may be a light deflection element.

  In the above embodiment, all of the four end surfaces of the transparent substrate are covered with the metal reflection film. However, if at least one of the end surfaces is covered with the reflection film, emission from the end surface is suppressed, Since light emission efficiency is improved, a configuration in which at least one sheet is covered may be used.

  In the above embodiment, the prism or the cylindrical lens is arranged directly on the exit surface. However, a sheet having a shape corresponding to the prism or the cylindrical lens formed on the surface is used as a light deflection element of the transparent substrate. The structure arrange | positioned on an output surface may be sufficient.

  Furthermore, the present invention provides an EL element other than the EL element having the structure as in the above embodiment, for example, a structure in which a light emitting layer and an electron transport layer are laminated, a hole transport layer, a light emitting layer, and an electron transport layer. The present invention can also be applied to an EL device using an EL element having a configuration in which layers are stacked.

  In the EL device of the above embodiment, the configuration in which the transparent anode 6 is disposed so as to be optically in close contact with the one surface 12a of the transparent substrate 12 is described. A plate-like cathode made of a body may be used, and this may be arranged so as to be optically in close contact with one surface 12a of the transparent substrate 12.

  Furthermore, although all the EL devices of the above-described embodiments use an organic EL element as a light emission source, the present invention may use an inorganic EL element instead of the organic EL element.

It is sectional drawing which shows typically the structure of the EL device of 1st Embodiment of this invention. It is sectional drawing which shows typically the structure of the EL device of 2nd Embodiment of this invention. It is sectional drawing which shows typically the structure of the EL device of 3rd Embodiment of this invention. It is sectional drawing which shows typically the structure of the EL device of 4th Embodiment of this invention. It is sectional drawing which shows typically the structure of the EL device of 5th Embodiment of this invention. It is the schematic which shows the structure of the conventional organic EL element typically.

Explanation of symbols

1: EL device 2: Organic EL element 4: Metal cathode 6: Transparent anode 8: Hole transport layer 10: Light emitting layer 12: Transparent substrate 12b: Outgoing surface 16: Prism

Claims (15)

A plate-like first electrode; a plate-like transparent second electrode provided on one surface of the transparent substrate; and a plate-like light emitting part disposed between the first and second electrodes. An EL device comprising:
An optical deflection element that is provided on the other surface of the transparent substrate and deflects the light emitted from the light emitting portion in the normal direction of the other surface;
An EL device characterized by that. At least one of the end faces of the transparent substrate is covered with a reflective material;
The EL device according to claim 1. The light deflection element comprises a plurality of prisms;
The EL device according to claim 1 or 2. The prism is disposed so as to taper toward the other surface of the transparent substrate, and has a surface that totally reflects light from the light emitting unit and deflects the light toward the normal direction of the other surface of the transparent substrate. Have
The EL device according to claim 3. The prism is disposed so as to expand toward the other surface of the transparent substrate, and has a surface that refracts light from the light emitting unit and deflects the light toward the normal direction of the other surface of the transparent substrate. Have
The EL device according to claim 3. The prism is a trapezoidal prism;
The EL device according to claim 4 or 5. The prism is a triangular prism;
The EL device according to claim 5. The light deflection element includes a plurality of cylindrical lenses.
The EL device according to claim 1 or 2. The cylindrical lens is disposed so as to be convex toward the other surface of the transparent substrate, and totally reflects light from the light emitting portion and deflects toward the normal direction of the other surface of the transparent substrate. Has a surface to
The EL device according to claim 8. The cylindrical lens is disposed so as to be convex in a direction opposite to the other surface of the transparent substrate, and refracts light from the light-emitting portion toward the normal direction of the other surface of the transparent substrate. Have a surface to deflect
The EL device according to claim 8. The light deflection element includes a large number of dots or recesses formed of a curved surface,
The EL device according to claim 1 or 2. The curved surface has an inclination angle of 30 degrees or more with respect to the other surface of the transparent substrate;
The EL device according to claim 11. The optical deflection element has optical anisotropy,
The EL device according to any one of claims 1 to 12. The pitch of the plurality of prisms is 15 μm or less;
The EL device according to claim 3. The light deflection element is formed of a UV curable resin.
The EL device according to claim 1.

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