JP2003282262A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device capable of providing a highluminance distribution over a wide visual field angle. <P>SOLUTION: This display device comprises: organic EL elements 110R, 110G and 110B for respective colors each having an oblong shape having a first side 130a and a second side 120a shorter than the first side 130a; reflecting surfaces 130b and 120b in the peripheries of the EL elements 110R, 110G and 110B for reflecting the light from the EL elements 110R, 110G and 110B to the viewing side; and an oblong panel part 140 for arranging the EL elements 110R, 110G and 110B. Each side 130a is nearly parallel to a side HL nearly horizontal to a viewer of the panel 140. <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 a display device, and more particularly to a display device suitable for a display for portable equipment or a display for stationary electronic equipment.

[0002]

2. Description of the Related Art An electroluminescence device (hereinafter referred to as "EL device") has a wide viewing angle because the EL material itself emits light, and has a high impact resistance because it is a completely solid-state device. At present, an inorganic EL element using an inorganic compound as a light emitting material and various organic EL elements using an organic compound as a light emitting material have been proposed. In particular, the latter organic EL element can emit light with high brightness at a low driving voltage, and thus, a display device using the organic EL element as a pixel has been recently developed. In such a display device, a plurality of organic EL elements are arranged and formed in a matrix, and these elements are independently driven to perform display.

Generally, an organic EL device has a transparent substrate,
It has a structure in which a transparent electrode, an organic light emitting layer, and a metal electrode are sequentially laminated. By applying a voltage to the transparent electrode and the metal electrode, holes and electrons are injected into the organic light emitting layer. The energy generated when these recombine excites the fluorescent substance. Light is emitted by utilizing the fact that the excited fluorescent substance causes a light emission phenomenon when returning to the ground state.

For the transparent electrode, a transparent conductor such as indium tin oxide (ITO) is used. In order to facilitate electron injection and increase luminous efficiency, the metal electrode should be
A substance having a small work function such as -Ag or Al-Li is used. The transparent electrode serves as the anode and the metal electrode serves as the cathode, but the reverse is also true. The organic light emitting layer has a thickness of about several tens of nm and is optically transparent.

Further, a hole transport layer is provided between the transparent electrode and the organic light emitting layer, an electron injection layer is provided between the metal electrode and the organic light emitting layer, or between the metal electrode and the organic light emitting layer or An adhesive layer may be provided between the electron injection layer and the organic light emitting layer. The organic light emitting layer is composed of one or more kinds of organic light emitting materials, but may be composed of a mixture of an organic light emitting material and a hole transporting material or an electron injecting material.

By the way, since the organic EL element is a self-luminous element, light is emitted in all directions including not only the front surface but also the periphery of the side surface. In addition, between the organic EL elements arranged in a matrix, the wiring for driving is formed in a grid shape, and there is a portion that looks black when viewed from the front. Therefore, the light emitting area ratio of the organic EL panel is about 60% due to the existence of the lattice portion, and the brightness is reduced accordingly.
Further, reflection occurs at the interface between the incident surface of a transparent medium such as a transparent electrode and the air, the amount of emitted light is reduced, and the light utilization efficiency is deteriorated. For example, in the case of an organic EL element, only about 1/4 of the total emitted light amount can be effectively used due to the influence of total reflection on the cover glass surface. Therefore, it is known to form a reflective surface on the outer periphery of a self-luminous element such as an EL element forming a pixel of a display device, which reflects the light of the self-luminous element to the observation side.

[0007]

However, although the light utilization efficiency is improved by the reflecting surface, it becomes difficult to obtain a wide viewing angle. Conventionally, it is simply EL due to the reflective surface
Since attention was paid only to guiding light from the element to the observation side, no consideration was given to the relationship between the inclination angle of the reflecting surface and the luminance distribution characteristic of light on the observation side. As a result, the field of view that can be observed with high brightness is limited, which may be very difficult to observe, which is a problem.

For example, in a portable device such as a mobile phone, an observer often views the screen by changing the angle of the mobile phone in the vertical (vertical) direction. In stationary electronic devices such as televisions and personal computers, an observer often changes the angle in the horizontal direction and views the screen.

As described above, the direction in which a wide viewing angle is required differs depending on the device in which the EL element is used. Then, as described above, in a mobile phone using the conventional EL element, for example, when the observer moves the face up and down to change the viewing angle, when the angle exceeds a certain angle range, the brightness is extremely lowered and the brightness becomes extremely high. Since it is difficult to observe, the above-mentioned problem becomes remarkable. on the other hand,
For example, in a television, when an observer moves his / her face left and right to change the viewing angle, beyond a certain range, the brightness is extremely lowered and the same problem occurs.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a display device which can obtain a high luminance distribution in a wide viewing angle.

[0011]

In order to solve the above-mentioned problems and to achieve the object, the present invention provides a rectangular shape having a first side and a second side shorter than the first side. A self-luminous element, a reflective surface provided on the outer periphery of the self-luminous element for reflecting light from the self-luminous element to an observation side, and a rectangular panel section for arranging the self-luminous elements, The display device is characterized in that the first side is substantially parallel or perpendicular to a side of the panel unit that is substantially horizontal to the observer. Thereby, a high brightness distribution can be obtained in a wide viewing angle.

According to a preferred aspect of the present invention, the first side is provided substantially parallel to the side of the panel section which is substantially horizontal to the observer, and the panel section is a stationary type. It is desirable to be incorporated in a display for electronic devices. As a result, the observer can obtain a high luminance distribution in a wide viewing angle in the horizontal direction.

Further, according to a preferred aspect of the present invention, the first side is provided substantially perpendicular to the side of the panel section which is substantially horizontal to an observer, and the panel section is a portable device. It is desirable to be incorporated into a display for automobiles. As a result, the observer can obtain a high luminance distribution in a wide viewing angle in the vertical direction.

Further, according to a preferred aspect of the present invention, it is preferable that the self-luminous element is composed of a red-light self-luminous element, a green-light self-luminous element, and a blue-light self-luminous element. Thereby, a full-color image can be displayed.

Further, according to a preferred aspect of the present invention, it is preferable that the reflecting surface is provided only in a direction along the first side. This makes it possible to obtain high-intensity light over a wide range at least in the range where the viewer changes the viewing angle. Further, since it is sufficient to form the groove only in the uniaxial direction, the production is easy.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. (First Embodiment) FIG. 1 is a perspective view showing a schematic configuration of an organic EL element display 100 according to a first embodiment of the present invention. FIG. 2 is a front view of this embodiment. The organic EL element display 100 according to this embodiment is used by being incorporated in a display for stationary electronic devices.
The organic EL element display 100 has a first side 130a.
And a second side 120a shorter than the first side 130a
And a red organic EL element 110R having a rectangular shape. In addition, a reflection surface 1 for reflecting the light from the organic EL element 110R on the outer periphery of the red organic EL element 110R to the observation side.
20b and 130b are provided.

Further, as shown in FIG. 2, red organic E
The L elements 110R are arranged in the rectangular panel section 140. Here, the first side 130a is the panel portion 1
It is provided so as to be parallel to a side HL that is substantially horizontal to 40 observers.

For example, the length of the first side 130a is about 14
The length of the second side 120a is 0 μm and is about 50 μm.
Then, an organic EL for green color having the same size and reflecting surface
The element 110G and the blue organic EL element 110B are arranged in three columns in the y direction. One pixel is composed of these three columns. Reflective surfaces 120b and 130b are formed around the organic EL elements 110R, 110G, and 110B.

FIG. 3 is a block diagram showing an organic EL panel according to this embodiment. This organic EL panel 100 includes organic EL elements 110R and 1R which are pixels on the first transparent substrate 1.
10G and 110B are formed in a matrix, and the second transparent substrate 3 is arranged on the organic light emitting film of the organic EL elements 110R, 110G, and 110B, and these are fixed by a transparent adhesive (adhesive layer 4). is there. V-grooves 5 are formed in a lattice pattern on the surface of the second transparent substrate 3 facing the first transparent substrate 1, except for the pixel portion, and a reflective film 6 is formed on the slopes of the V-grooves 5. ing. Thus, R, G, and B pixels (110R,
110G and 110B) are formed. The reflection film 6 of the V groove 5 can be observed from the front side. Then, the V-shaped groove 5 on which the reflective film 6 is formed forms the reflective surface 130b.

As a material for the first transparent substrate 1 and the second transparent substrate 3, a glass plate or a polymer plate can be used.
As the glass, quartz glass, soda lime glass, borate glass, phosphate glass, phosphosilicate glass, silicate glass or the like can be used. Further, as the polymer plate, polycarbonate, polyethylene terephthalate, polyether sulfone, polyacrylate, polymethacrylate or the like can be used.

The V groove 5 of the second transparent substrate 3 is formed by a removal process such as machining. In addition to removing the surface of the second transparent substrate 3 to form the V groove 5, a trapezoidal portion 7 (represented by a dotted line in the drawing) formed between the grooves may be formed by ink jetting or die transfer. good. The reflective film 6 formed in the V groove 5 can be formed by using the same material as the mirror-finished metal electrode used for the cathode.

The reflective film 6 is formed in a matrix by coating one surface of the second transparent substrate 3 with a predetermined material by a vapor deposition method or the like, and then removing the portions to be pixels (corresponding to 110R, 110G, 110B) by etching. The reflection film 6 covers the inner surface of the V groove 5.

Next, the materials of the constituent elements of the organic EL panel 100 will be shown (hereinafter, the same materials are used in principle for the same members). Organic EL elements 110R, 110G, 11
OB has a structure in which a transparent electrode, an organic light emitting layer, and a metal electrode are sequentially laminated. The lamination method includes a resistance heating vacuum deposition method, an electron beam heating vacuum deposition method, a sputtering method, an ion plating method, a casting method, A spin coating method or the like can be used as appropriate. First, after forming an ITO film as a transparent electrode (anode) by a sputtering method, this substrate is ultrasonically cleaned and purified water is cleaned. The substrate after cleaning was fixed to a holder of a commercially available vacuum vapor deposition apparatus, and TPD (N, N'-diphenyl-
N, N'-bis- (3-methylphenyl)-[1,1 '
-Biphenyl] -4,4'-diamine) is deposited on the ITO film to form a hole transport layer.

Subsequently, the organic light emitting layer is formed on the hole transport layer while the substrate on which the hole transport layer is formed is kept in the vacuum chamber. The organic light emitting layer is formed by depositing Alq on the hole transport layer at a predetermined vapor deposition rate. Next, magnesium and indium are put into a heating board and heated to evaporate at a predetermined deposition rate to form a metal electrode (cathode) made of a mixed metal of magnesium and indium on the organic light emitting layer.

As the material of the transparent electrode, a metal, an alloy, an electrically conductive compound or a mixture thereof which has a large work function and can obtain a desired transparent electrode (transparent conductive film) can be used. Is a metal such as Au, ITO,
A dielectric transparent material such as SnO ₂ or ZnO can be used as appropriate. As a material of the metal electrode, a metal having a low work function, an alloy, an electrically conductive compound, or a mixture thereof can be used, and specifically, sodium,
Examples thereof include magnesium, lithium, alloys or mixed metals of magnesium and silver, indium, rare earth metals and the like.

Examples of materials for the organic light-emitting layer include benzothiazole-based, benzimidazole-based, and benzoxazole-based fluorescent whitening agents, metal chelated oxinoid compounds, styrylbenzene-based compounds, distyrylpyrazine derivatives, and aromatic dimethylidene. A compound or the like can be used.

The organic light emitting layer may be made of only the organic light emitting material, or may be made of a mixture of the organic light emitting material, the hole transporting material and the electron injecting material. In this case, as the material of the organic light emitting layer, a molecular dispersion polymer system in which a small amount of an organic light emitting material such as coumarin is dispersed in a polymer such as bisphenol A, polycarbonate (PC), polymethylmethacrylate, or distyrylbenzene in a polycarbonate skeleton. Polyphenylene vinyl containing derivative (PPV)
Derivatives, polymers, polyalkylfluorenes (PA
F) derivative-based, polyalkylthiophene (PAT) -derivative, polyarylene (PA) -derivative, polyphenylene (PP) -derivative-based conjugated polymers, or electron-injecting oxadiene in hole-transporting polyvinylcarbazole. A system in which an azole derivative is dispersed can be appropriately used.

Materials for the hole transport layer include triazole derivatives, amino-substituted chalcone derivatives, polyarylalkane derivatives, pyrazoline derivatives, phenylenediamine derivatives, aniline-based copolymers, oxadiazole derivatives,
Imidazole derivatives, arylamine derivatives, polysilane compounds, pyrazolone derivatives, oxazole derivatives,
Specific conductive polymer oligomers such as styrylanthracene derivatives, fluorenone derivatives, silazane derivatives, and thiophene oligomers can be used.

In addition, the organic EL elements 110R and 110
An electron injection layer may be provided in G and 110B, and the material of the electron injection layer is a diphenylquinone derivative,
Heterocyclic tetracarboxylic acid anhydrides such as nitro-substituted fluorenone derivatives, thiopyran dioxide derivatives, anthraquinodimethane derivatives, naphthaleneperylene, carbodiimides, oxadiazole derivatives, anthrone derivatives, fluorenylidenemethane derivatives, anthraquinodimethane derivatives , 8-quinolinol derivatives, other specific electron transfer compounds, and the like can be used.

As a material for the adhesive layer 4, a metal complex of 8-quinolinol or a derivative thereof, for example, tris (8-quinolinol) aluminum, bis (2-methyl-8-quinolinato) aluminum oxide, bis (2-methyl-8) is used.
-Quinolinol) beryllium, bis (8-quinolinol) magnesium, bis (benzo-8-quinolinol)
Zinc, tris (8-quinolinol) indium, tris (5-methyl-8-quinolinol) aluminum, bis (5-chloro-8-quinolinol) calcium, tris (5,7-dichloro-8-quinolinol) aluminum, tris ( 5,7-Dibromo-8-hydroxyquinolinol) aluminum, 8-quinolinol lithium, tris (5-chloro-8-quinolinol) gallium, bis (2-methyl-8-quinolinol) zinc, tris (7-
Propyl-8-quinolinol) aluminum, bis (8
-Quinolinol) tin or the like can be used.

Next, the relationship between the viewing angle and the luminance distribution of the organic EL element display 100 according to this embodiment will be described. FIG. 4 is a diagram showing a luminance distribution when the organic EL element does not have a reflecting surface. The solid line xx shows the luminance distribution in the x direction, and the broken line yy shows the luminance distribution in the y direction. Further, FIG. 5 is a diagram showing a luminance distribution when the organic EL element has a reflection surface.

As is apparent from comparison between FIGS. 4 and 5, the use of the reflection surface improves the light utilization efficiency by about 3 times in the front. Also, the brightness can be maintained in all directions. The viewing angle at which the brightness is about half is ± 60 ° with respect to the front. In this way, a bright and wide viewing angle can be obtained in the x direction (horizontal direction).

As the stationary electronic equipment, for example, 13.
A device such as a laptop computer or desktop computer equipped with a display up to about 3 inches class, or 14
Examples include TVs with inches or more.

(Second Embodiment) FIG. 6 is a view showing the schematic arrangement of an organic EL element display 200 according to the second embodiment of the present invention. In the present embodiment, the first side 130a of each color organic EL element 110R, 110G, 110B.
However, it is different from the first embodiment in that it is provided so as to be vertical to a side HL that is substantially horizontal to the observer of the panel 140. The other parts similar to those of the above-described first embodiment are designated by the same reference numerals, and overlapping description will be omitted.

In this embodiment, a bright and wide viewing angle can be obtained in the y direction (vertical direction). Therefore, it is suitable for a display for, for example, a mobile phone, a wrist watch, and a portable personal information terminal (PDA).

In each of the above embodiments, the first side 13
The reflecting surface 130b may be provided only in the direction along 0a. Thereby, even if the other reflection surface 120b is not provided,
It is possible to obtain high-intensity light over a wide range within a range where the observer changes the viewing angle. Further, since it is sufficient to form the groove only in the uniaxial direction, the production is easy. The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

[0037]

As described above, according to the present invention,
It is possible to provide a display device that can obtain a high luminance distribution in a wide viewing angle.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of an organic EL element display according to a first embodiment of the present invention.

FIG. 2 is a front view showing a schematic configuration of an organic EL element display self-luminous display according to the first embodiment.

FIG. 3 is a diagram showing a cross-sectional structure of the organic EL element display according to the first embodiment.

FIG. 4 is a diagram showing a luminance distribution when there is no reflective surface.

FIG. 5 is a diagram showing a luminance distribution when there is a reflecting surface.

FIG. 6 is a front view showing a schematic configuration of an organic EL element display according to a second embodiment of the present invention.

[Explanation of symbols]

1 First transparent substrate 3 Second transparent substrate 4 Adhesive layer 5 V groove 6 Reflective film 7 trapezoidal part 100 Organic EL element display 110R, 110G, 110B Organic EL element for each color 120a second side 130a First side 120b, 130b Reflective surface 140 panel section Horizontal side of HL panel

Claims (5)

[Claims] 1. A self-luminous element having a rectangular shape having a first side and a second side shorter than the first side, and light from the self-luminous element provided on the outer periphery of the self-luminous element. Has a reflection surface for reflecting to the observation side, and a rectangular panel portion in which the self-luminous elements are arranged, and the first side is with respect to a side substantially horizontal to the observer of the panel portion. A display device characterized by being substantially parallel or vertical. 2. The first side is provided substantially parallel to the side that is substantially horizontal to an observer of the panel section, and the panel section is incorporated in a display for a stationary electronic device. The display device according to claim 1, wherein the display device is a display device. 3. The first side is provided substantially perpendicular to the side of the panel section that is substantially horizontal to an observer, and the panel section is incorporated in a display for a mobile device. The display device according to claim 1. 4. The self-luminous element comprises a red light self-luminous element, a green light self-luminous element, and a blue light self-luminous element. Display device. 5. The display device according to claim 4, wherein the reflective surface is provided only in a direction along the first side.