JP2006018187A - Organic el display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL display device which has high contrast, makes good image display possible and has a long product lifetime. <P>SOLUTION: The organic EL display device 1 is equipped with an organic EL element 10 having a light reflection electrode 12 and a light emitting layer 13 prepared on the light reflection electrode 12, and emitting the direct light of the emitted light of the light emitting layer 13 and the light reflected on the light reflection electrode 12 to an observer side, a circularly polarizing plate 30 obstructing the emission of the external light made incident from the observer side and reflected at the light reflection electrode 12 and the exit of the reflected light again to the observer side, and a bezel 20 which holds the circularly polarizing plate 30 apart from the organic EL element 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an organic EL display device.

  In recent years, with the diversification of information processing equipment, there has been an increasing demand for flat display devices that consume less power than conventional cathode ray tubes (CRTs) and can be reduced in thickness. Examples of such a flat display device include a liquid crystal display device and an EL (electroluminescence) display device. Among them, the organic EL display device has features such as low voltage driving, all solid-state type, high-speed response, and self-luminous property.

  FIG. 6 is a schematic cross-sectional view of a conventional organic EL display device 200.

  The organic EL display device 200 includes a substrate 210, a light emitting layer 230 provided on the substrate 210, and a first electrode 220 and a second electrode 240 provided so as to sandwich the light emitting layer 230.

  In the organic EL display device 200, the second electrode 240 is configured to be light-reflective and the first electrode 220 is configured to be light-transmissive, so that light from the light emitting layer 230 is emitted from the first electrode 220 side. It is configured.

  In the organic EL display device 200, the first electrode 220 and the light emitting layer 230 are configured to be very thin. Therefore, the external light incident from the observer side via the substrate 210 reaches the second electrode 240 and is reflected again to the observer side by the second electrode 240 configured to be light reflective. Accordingly, there is a problem that an external scenery is reflected on the organic EL display device 200 together with the display image, and the contrast and color purity of the organic EL display device 200 are lowered.

  In view of such a problem, an organic EL display device in which a circularly polarizing plate is provided on the first electrode side configured to be light transmissive has been proposed (for example, “Patent Document 1” or the like).

  FIG. 5 is a schematic cross-sectional view of the organic EL display device 100 described in Patent Document 1.

  The organic EL display device 100 includes a circularly polarizing plate including a linearly polarizing plate 110 and a retardation plate 120, a transparent substrate 130, an anode 140, a hole injecting and transporting layer 150, an organic light emitting layer 160, and an electron injecting and transporting. The layer 170 and the cathode 180 are laminated in this order.

In Patent Document 1, right-handed and left-handed circularly polarized light can be obtained by tilting the angle formed by the polarization axis of the linearly polarizing plate 110 and the optical axis of the phase difference plate 120 to ± 45 °. The characteristic of circularly polarized light is that the direction of circularly polarized light is changed by reflection. That is, right-handed circularly polarized light becomes left-handed circularly polarized light, and left-handed circularly polarized light becomes right-handed circularly polarized light when reflected. Light incident from the outside and transmitted through the circularly polarizing plate becomes right or left circularly polarized light, is reflected by the cathode 180 on the back surface, and travels toward the outside of the organic EL display device 100. However, since it is circularly polarized light in the direction opposite to the incident light, the circularly polarizing plate does not transmit the reflected light, and it is described that the external scenery due to reflection cannot be seen.
Japanese Patent Laid-Open No. 8-322138

  Since the organic EL display device 100 is a self-luminous display device and a current-driven light-emitting device, the light-emitting layer 160 generates heat particularly when image display is performed continuously. Further, the heat-resistant temperature of the linearly polarizing plate 110 and the retardation plate 120 is generally as low as about 90 ° C. even if it is high at 70 ° C. Therefore, in the organic EL display device 100 in which the linear polarizing plate 110 and the retardation plate 120 are bonded to the light emitting layer 160 that generates heat, the heat generation of the light emitting layer 160 is easily conducted to the linear polarizing plate 110 and the retardation plate 120. Thermal degradation of the linear polarizing plate 110 and the retardation plate 120 is severe. Therefore, the organic EL display device 100 has a problem that its product life is short.

  The present invention has been made in view of the above points, and an object thereof is to provide an organic EL display device having a high contrast, capable of displaying a good image and having a long product life. There is to do.

The organic EL display device according to the present invention has a light reflecting layer and a light emitting layer provided on the light reflecting layer, and observes direct light emitted from the light emitting layer and light reflected by the light reflecting layer. An organic EL element that emits light to a person,
A light reflection preventing plate that is provided on the viewer side of the organic EL element and prevents the reflected light of the external light incident from the viewer side from being emitted to the viewer side again;
Holding means for holding the light reflection preventing plate away from the organic EL element;
It is equipped with.

  Since the organic EL display device according to the present invention includes the light reflection preventing plate, the reflected light from the light reflection layer of the external light incident from the observer side is prevented from being emitted again to the observer side. . Therefore, it is possible to realize an organic EL display device having high contrast and capable of displaying a good image.

  In the organic EL display device according to the present invention, the light reflection preventing plate is disposed apart from the organic EL element. Therefore, the heat generated by the organic EL element is not directly conducted to the light reflection preventing plate. Therefore, it is possible to effectively suppress deterioration due to heat generation of the organic EL element of the light reflection preventing plate, and to realize an organic EL display device having a long product life.

Further, in the organic EL display device according to the present invention, the organic EL element has a transparent substrate provided closer to the observer side than the light emitting layer,
The holding means may be constituted by a bezel to which the transparent substrate is fixed.

  In the organic EL display device according to the present invention, the bezel may have a higher thermal conductivity than the transparent substrate.

  According to this configuration, the organic EL element is bonded and fixed to the bezel having a thermal conductivity larger than that of the transparent substrate. Therefore, the heat generated by the organic EL element is effectively radiated to the outside of the organic EL display device via the bezel having high thermal conductivity. Therefore, it can suppress more effectively that the heat_generation | fever of an organic EL element is conducted to a light reflection preventing board.

  Furthermore, according to this configuration, the heat generated in the organic EL element is effectively radiated to the outside via the bezel, so that the heat storage in the organic EL element can be effectively suppressed.

  Therefore, according to this configuration, the thermal degradation of the organic EL element and the light reflection preventing plate can be more effectively suppressed, and an organic EL display device having a longer product life can be realized.

  In the organic EL display device according to the present invention, the light reflection preventing plate may be positioned 0.1 mm or more away from the organic EL element.

  According to this configuration, conduction of heat generated from the organic EL element to the light reflection preventing plate can be more effectively suppressed. Therefore, an organic EL display device having a longer product life can be realized.

  In the organic EL display device according to the present invention, the bezel may be formed of metal.

  By forming the bezel from metal, a bezel having high thermal conductivity can be realized. Therefore, the heat generated by the organic EL element is effectively radiated to the outside through the bezel having high thermal conductivity. Therefore, heat conduction from the organic EL element to the light reflection preventing plate can be more effectively suppressed. Moreover, it can suppress more effectively storing an organic EL element.

  Therefore, according to this configuration, the thermal degradation of the organic EL element and the light reflection preventing plate can be further effectively suppressed, and an organic EL display device having a longer product life can be realized.

  In the organic EL display device according to the present invention, the bezel may have an annular contact surface with the organic EL element.

  According to this configuration, the bezel is bonded and fixed so as to cover the entire peripheral portion located outside the display area of the organic EL display element. Therefore, the heat generated by the organic EL display element is more effectively conducted to the bezel and radiated. Therefore, according to this structure, the thermal deterioration of the organic EL element and the light reflection preventing plate can be further effectively suppressed, and an organic EL display device having a longer product life can be realized.

  In the organic EL display device according to the present invention, the bezel may be provided with a vent hole that allows the space between the organic EL element and the light reflection preventing plate to communicate with the outside air. Absent.

  According to this configuration, the air layer formed between the organic EL element and the light reflection preventing plate communicates with the outside air. Therefore, the heat generated by the organic EL element stored in the air layer is effectively released outside the organic EL display device. Therefore, according to this configuration, it is possible to effectively suppress the thermal deterioration of the organic EL element and the light reflection preventing plate, and it is possible to realize an organic EL display device having a longer product life.

  In the organic EL display device according to the present invention, the light reflection preventing plate is composed of a polarizing plate provided on the observer side and a retardation plate provided on the organic EL element side. It does not matter.

  According to this configuration, it is possible to prevent the external light that is incident from the viewer side and reflected again to the viewer side by the light reflection layer from being emitted from the organic EL display device. That is, light incident from the observer side is converted into circularly polarized light by a circularly polarizing plate composed of a polarizing plate and a retardation plate. Then, the converted circularly polarized light is reflected by the light reflecting layer, thereby changing to circularly polarized light that is reverse to the incident light. Thus, the circularly polarized light that has been reflected by the light reflecting layer and converted into a reverse winding with respect to the incident light cannot pass through the circularly polarizing plate, and therefore does not exit to the viewer side again.

  Therefore, according to this configuration, an organic EL display device having high contrast and capable of displaying a good image can be realized.

  In the organic EL display device according to the present invention, the light reflection preventing plate may have an anti-reflection coating layer and / or an anti-glare coating layer on the observer side surface.

  According to this structure, the light reflection which generate | occur | produces on the surface of a light reflection prevention board can be suppressed effectively. Therefore, an organic EL display device with high visibility of the display image can be realized.

  Further, in the organic EL display device according to the present invention, the light reflection preventing plate has an anti-reflection coating layer and / or an anti-glare coating layer on the observer side surface, and a polarizing plate provided on the observer side, You may be comprised by the phase difference plate provided in the organic EL element side.

  According to this configuration, the external light incident from the observer side and reflected by the light reflecting layer is emitted again to the observer side, and the light reflection generated on the surface of the antireflection plate is effectively suppressed. can do. Therefore, according to this configuration, it is possible to realize an organic EL display device having high visibility, high contrast, and capable of displaying a good image.

  As described above, according to the present invention, the light reflection preventing plate having a function of preventing light incident from the observer side and reflected by the light reflecting layer from being emitted again to the observer side, Further, since the light reflection preventing plate is provided apart from the organic EL element, it is possible to suppress deterioration in display image quality such as a decrease in contrast due to incident light from the observer side, and also due to heat generation of the organic EL element. Deterioration of the light reflection preventing plate and the organic EL element can be suppressed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view of an organic EL display device 1 according to an embodiment of the present invention.

  2 is a schematic cross-sectional view of a portion indicated by II-II in FIG.

  The organic EL display device 1 includes an organic EL element 10, a bezel 20 bonded and fixed to the outer edge portion of the organic EL element 10, a transparent substrate 40 bonded to the organic EL element 10 by the bezel 20, and a bezel 20. And the circularly polarizing plate 30 formed.

  The organic EL element 10 includes a first substrate 11, a light reflecting electrode 12 provided on the first substrate 11, a light emitting layer 13 provided on the light reflecting electrode 12, and a light emitting layer 13. The transparent electrode 14 and the second substrate 15 provided on the transparent electrode 14 are configured so that light from the light emitting layer 13 is emitted from the transparent electrode 14 side. In the organic EL element 10, only the light emitting layer 13 is provided between the light reflecting electrode 12 and the transparent electrode 14, but the present invention is not limited to this configuration. That is, of course, a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, or the like may be further provided between the light reflecting electrode 12 and the transparent electrode 14.

  Moreover, in the organic EL element 10, although the light reflection electrode 12 was provided on the 1st board | substrate 11, this invention is not limited to this at all. That is, it goes without saying that a light reflecting layer is provided on the first substrate 11 and a transparent electrode is provided thereon.

The first substrate 11 and the second substrate 15 are not limited as long as the mechanical strength of the organic EL element 10 can be secured. The first substrate 11 and the second substrate 15 are, for example, substrates made of an inorganic material such as glass or quartz, a plastic such as polyethylene terephthalate, and an insulating material such as ceramics such as alumina, or a metal such as aluminum or iron. The substrate can be constituted by a substrate coated with an insulating material such as SiO ₂ or an organic insulating material, or a substrate obtained by subjecting the surface of a metal substrate such as aluminum or iron to insulation treatment by a method such as anodization. .

  In addition, since the 2nd board | substrate 15 has a function which permeate | transmits the light from the light emitting layer 13, it is preferable to comprise in the light transmittance. That is, the second substrate 15 is more preferably composed of, for example, an inorganic material such as glass or quartz, or a plastic such as polyethylene terephthalate.

  The light reflecting electrode 12 has a function of reflecting light emitted from the light emitting layer 13 toward the light reflecting electrode 12 to the viewer side and a function of injecting holes into the light emitting layer 13. Therefore, the light reflecting electrode 12 is preferably made of a material having a high light reflectivity and a large work function.

  Examples of the material having a high light reflectance include aluminum (Al) and platinum (Pt). Examples of the material having a large work function include indium tin oxide (ITO), indium zinc oxide (IZO), gold (Au), platinum (Pt), and nickel (Ni).

  Of course, the light reflection electrode 12 may have a laminated structure of a metal layer having a light reflection function and a hole injection layer having high hole injection efficiency. According to this configuration, it is possible to realize the organic EL element 10 having high light extraction efficiency from the light emitting layer 13, high current efficiency, and high luminance.

  The transparent electrode 14 has a function of transmitting light from the light emitting layer 13 to the viewer side and a function of injecting electrons into the light emitting layer 13. Therefore, the transparent electrode 14 is more preferably made of a material having a high electric conductivity, a high light transmittance, and a small work function. Examples of the material having high electrical conductivity and high light transmittance include transparent conductive oxides such as indium tin oxide (ITO) and indium zinc oxide (IZO). Examples of the material having a small work function include calcium (Ca) and barium (Ba).

  Of course, the transparent electrode 14 may have a laminated structure of an electron injection layer made of a material having a small work function and a transparent electrode layer having high light transmittance and high electrical conductivity. According to this configuration, the organic EL element 10 having high electron injection efficiency into the light emitting layer 13 and high light extraction efficiency from the light emitting layer 13 can be realized.

  In the organic EL element 10, the light reflecting electrode 12 has a hole injection function and the transparent electrode 14 has an electron injection function. However, the present invention is not limited to this structure. . That is, the light reflecting electrode 12 may have an electron injection function, and the transparent electrode 14 may have a hole injection function.

The light emitting layer 13 recombines holes injected from the light reflecting electrode 12 and electrons injected from the transparent electrode 14 to generate excitons (exons), and the light generated when the excitons are deactivated. It is formed of an organic light emitting material that emits light by utilizing emission. Examples of such organic light-emitting materials include aromatic compounds such as 4,4′-bis (2,2′-diphenylvinyl) -biphenyl (DPVBi), oxadiazole compounds, and 3- (4-biphenylyl). Triazol derivatives such as -4-phenyl-5-t-butylphenyl-1,2,4-triazole (TAZ), styrylbenzene compounds such as 1,4-bis (2-methylstyryl) benzene, thiopyrazinedi Fluorescent organic materials such as oxide derivatives, benzoquinone derivatives, naphthoquinone derivatives, anthraquinone derivatives, diphenoquinone derivatives, fluorenone derivatives, azomethine zinc complexes, fluorescent organometallic compounds such as (8-hydroxyquinolinato) aluminum complexes (Alq ₃ ), etc. A low molecular weight light emitting material, for example, poly (2-decyloxy-1,4 Phenylene) (DO-PPP), poly [2,5-bis- [2- (N, N, N-triethylammonium) ethoxy] -1,4-phenyl-alt-1,4-phenyllene] dibromide ( PPP-NEt ³⁺ ), poly [2- (2′-ethylhexyloxy) -5-methoxy-1,4-phenylenevinylene] (MEH-PPV), poly [5-methoxy- (2-propanoxysulfonide) ) -1,4-phenylene vinylene] (MPS-PPV), poly [2,5-bis- (hexyloxy) -1,4-phenylene- (1-cyanovinylene)] (CN-PPV), poly (9, Examples thereof include polymer light emitting materials such as 9-dioctylfluorene (PDAF) and polyspiro (PS).

  The circularly polarizing plate 30 has a function of preventing light incident from the viewer side and reflected by the light reflecting electrode 12 from being emitted to the viewer side. Therefore, the organic EL display device 1 which can display a good image with high contrast and color purity without causing an external scenery to appear on the organic EL display device 1 together with the display image can be realized. .

  In addition, a circularly-polarizing plate can be comprised by the linear polarizing plate provided in the observer side, and the (lambda) / 4 phase difference plate provided in the organic EL element side.

  Further, in the organic EL display device 1, the circularly polarizing plate 30 is a light reflection preventing plate having a function of preventing external light incident from the observer side and reflected by the light reflecting electrode 12 from being emitted again to the observer side. However, the light reflection preventing plate is not limited to this in the present invention.

  That is, the light reflection preventing plate is, for example, an elliptically polarizing plate, an anti-glare coat (anti-glare coat; hereinafter may be abbreviated as “AG coat”) layer and / or an anti-reflection coating (non-reflective coat; Hereinafter, it may be abbreviated as “AR coating.”) Of course, a transparent substrate having a layer or the like may be used. Further, the light reflection preventing plate may be constituted by a linear polarizing plate having an AG coat layer and / or an AR coat layer formed on the surface, and a λ / 4 retardation plate.

  By using an antireflection plate having an AG coat layer and / or an AR coat layer, light reflection by the observer side surface of the antireflection plate can be suppressed, and an organic EL display device 1 with high visibility is realized. can do.

  The protective substrate 40 protects the organic EL element 10 and the circularly polarizing plate 30 from external impacts, and improves the physical durability of the organic EL display device 1. The protective substrate 40 is not limited as long as it has a high light transmission property, but can be made of, for example, a plastic such as glass or acrylic.

  The bezel 20 has a function of bonding the organic EL element 10 to the circularly polarizing plate 30 and the protective substrate 40. The circularly polarizing plate 30 is disposed so as to be separated from the organic EL element 10 by the bezel 20. Therefore, the heat generated by the organic EL element 10 is not directly conducted to the circularly polarizing plate 30, and thermal deterioration of the circularly polarizing plate 30 can be effectively suppressed. In addition, the layer thickness of the bezel 20 is preferably 0.1 or more, and more preferably 0.3 mm or more. According to this configuration, the distance between the circularly polarizing plate 30 and the organic EL element 10 can be increased, and the circularly polarizing plate 30 can be more effectively protected from the heat generation of the organic EL element 10.

  The bezel 20 is made of a metal having high thermal conductivity such as aluminum (Al), iron (Fe), stainless steel, or the like. Therefore, the heat generated by the organic EL element 10 can be effectively released outside the organic EL display device 1. Therefore, thermal deterioration of the circularly polarizing plate 30 and the organic EL element 10 can be more effectively suppressed.

  In addition, as shown in FIG. 2, the bezel 20 is formed with a vent 21 for communicating an air layer formed between the circularly polarizing plate 30 and the transparent substrate 40 to the outside air. Therefore, the heat generated by the organic EL element 10 stored in the air layer is effectively released from the organic EL display device 1. Therefore, according to this configuration, the thermal deterioration of the circularly polarizing plate 30 can be effectively suppressed, and the organic EL display device 1 having a longer product life can be realized.

  FIG. 3 is a plan view showing variations in the shape of the bezel 20.

  FIG. 4 is a schematic cross-sectional view of the organic EL display device 1 when the bezel 20 has the shape shown in FIG.

  As shown in FIG. 3A, the bezel 20 may be provided such that the bonding portion 20 a is annular on the entire peripheral portion of the organic EL element 10. According to this configuration, since the bezel 20 having high thermal conductivity is bonded and fixed to the organic EL display element 10 in a wider area, the heat generated by the organic EL display element 10 is effectively conducted to the bezel 20, Heat is dissipated. Therefore, the organic EL display device 1 having a high heat dissipation effect by the bezel 20 can be realized.

  Further, as shown in FIGS. 4B to 4D, the bezel 20 may have an adhesive portion 20 a provided on a part of the outer edge portion of the organic EL element 10. According to this configuration, as shown in FIG. 4, the portion that is not bonded to the bezel 20 becomes the vent hole 20 b that communicates the space between the organic EL element 10 and the circularly polarizing plate 30 to the outside air. Therefore, the heat generated by the organic EL element 10 stored in this space is more effectively released to the outside of the organic EL display device 1 by convection of air. Therefore, according to this configuration, the thermal deterioration of the organic EL element 10 and the circularly polarizing plate 30 can be further effectively suppressed, and the organic EL display device 1 having a longer product life can be realized.

  In the present invention, the organic EL element 10 is not limited in any way, and may be an active matrix element having a switching element such as a TFT on the substrate 11, or a passive matrix element, It may be a segment type element.

1 is a schematic cross-sectional view of an organic EL display device 1 according to the present invention. It is a schematic sectional drawing of the part shown by II-II in FIG. FIG. 6 is a plan view showing variations in the shape of the bezel 20. It is a schematic sectional drawing of the organic electroluminescence display 1 in case the bezel 20 has the shape shown in FIG.3 (b). 1 is a schematic cross-sectional view of an organic EL display device 100 described in Patent Document 1. FIG. It is a schematic sectional drawing of the conventional organic electroluminescent display apparatus 200. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,100,200 Organic EL display apparatus 10 Organic EL element 11 1st board | substrate 12 Light reflection layer 13,170,230 Light emitting layer 14 Transparent electrode 15 2nd board | substrate 20 Bezel 20a Adhesive part 21, 20b Vent hole 30 Circularly polarizing plate 40 Protective substrate 110 Linear polarizing plate 120 Phase difference plate 130 Glass substrate 140 Anode 150 Hole transport layer 160 Light emitting layer 180 Cathode 210 Substrate 220 First electrode 240 Second electrode

Claims (10)

An organic EL element having a light reflecting layer and a light emitting layer provided on the light reflecting layer, and emitting direct light emitted from the light emitting layer and light reflected by the light reflecting layer to an observer; ,
A light reflection preventing plate that is provided on the viewer side of the organic EL element and prevents the reflected light of the external light incident from the viewer side from being emitted to the viewer side again;
Holding means for holding the light reflection preventing plate away from the organic EL element;
An organic EL display device. The organic EL display device according to claim 1,
The organic EL element has a transparent substrate provided closer to the viewer than the light emitting layer,
The holding means is an organic EL display device including a bezel to which the transparent substrate is fixed. The organic EL display device according to claim 2,
The bezel is an organic EL display device having higher thermal conductivity than the transparent substrate. The organic EL display device according to claim 1,
The organic EL display device, wherein the light reflection preventing plate is positioned at least 0.1 mm away from the organic EL element. The organic EL display device according to claim 2,
An organic EL display device in which the bezel is made of metal. The organic EL display device according to claim 2,
The bezel is an organic EL display device in which a contact surface with the organic EL element is formed in an annular shape. The organic EL display device according to claim 2,
An organic EL display device in which a vent hole is formed in the bezel so that a space between the organic EL element and the light reflection preventing plate communicates with outside air. The organic EL display device according to claim 1,
The said light reflection prevention board is an organic electroluminescence display comprised by the polarizing plate provided in the observer side, and the phase difference plate provided in the organic EL element side. The organic EL display device according to claim 1,
The light reflection preventing plate is an organic EL display device having an anti-reflection coating layer and / or an anti-glare coating layer on the observer side surface. The organic EL display device according to claim 8,
The light reflection preventing plate is an organic EL display device having an anti-reflection coating layer and / or an anti-glare coating layer on the observer side surface.

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