JP2003282263A - Reflector for display panel, display panel, electronic equipment - Google Patents

Abstract

(57) [Problem] To provide a reflector for a display panel, a display panel, and an electronic device capable of obtaining a bright image by increasing light use efficiency. A light emitting element forming a pixel of a display device is provided.
0 and at least the light emitting region 101 of the light emitting element 110
And a plurality of reflectors 120 for reflecting light from the light emitting element 110 to the observation side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique suitable for a display panel reflector, a display panel, an electronic device, and particularly a display panel using a self-luminous display element.

[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.

FIG. 13A is a diagram showing a schematic structure of a conventional display panel 1 having a reflecting surface. Organic EL element 2
A reflective surface 3 is formed on the outer periphery of the. Organic EL element 2
The light L1 emitted from is reflected directly by the reflection surface 3 and emitted from the cover glass surface 4.

[0008]

However, as shown in FIG.
As shown in (b), of the light emitted from the organic EL element 2, the light that is totally reflected by the cover glass surface 4 and then enters the reflecting surface 3 cannot be emitted from the cover glass surface 4. In this way, the region 5 in which there is light that cannot be emitted is indicated by hatching. Therefore, even when the reflective surface 3 is formed on the outer periphery of the organic EL element, the light utilization efficiency is not sufficient, which is a problem.

In order to reduce the area of the region 5 where the light that cannot be emitted from the cover glass surface 4 exists, the reflecting surface 3
It is sufficient to increase the height h. However, it is difficult to manufacture the reflecting surface 3 having a large height h. Therefore, it is difficult and problematic to improve the light utilization efficiency in the conventional configuration.

The present invention has been made to solve the above-mentioned problems, and a reflector for a display panel, a display panel, which can obtain a bright image by increasing the utilization efficiency of light.
The purpose is to provide an electronic device.

[0011]

In order to solve the above problems and achieve the object, the present invention provides a light emitting element forming a pixel of a display device, and a light emitting element provided in at least a light emitting region of the light emitting element. And a plurality of reflecting portions for reflecting the light from the light emitting element to the observing side. As a result, it is possible to obtain a bright image by increasing the light utilization efficiency by the small reflecting portion.

Further, according to a preferred aspect of the present invention, the reflecting portion is configured to allow an incident light from the light emitting element to enter an interface of a transparent medium through which light of the light emitting element transmits, at an angle exceeding a critical angle for causing total reflection. It is desirable to have an inclination angle so that light is reflected by the reflection portion and the reflected light is incident on the interface at a angle less than the critical angle. Thereby, the light emitted from the light emitting element at any angle can be extracted on the observation side.

According to a preferred aspect of the present invention, the first substrate having a plurality of the light emitting elements provided on the surface thereof, and the first substrate
A transparent second substrate disposed so as to overlap the substrate, and a transparent medium layer provided between the first substrate and the second substrate, wherein the reflecting portion is the light emitting region of the light emitting element. Up,
Alternatively, it is preferably formed on the surface of the second substrate facing the light emitting element. Thereby, the light emitting element can be sealed between the substrates. Therefore, an organic EL element or the like which requires airtightness can be used as the light emitting element.

Further, according to a preferred aspect of the present invention, the transparent medium layer is preferably an adhesive layer. Thereby, higher airtightness can be obtained. In addition, according to a preferred aspect of the present invention, it is desirable that a partition wall portion provided between the light emitting element and the reflection portion is further included. Accordingly, the light emitting element can be selectively formed in a region other than the region where the reflection portion is provided. Therefore, the light utilization efficiency can be improved because the light is not shielded by the reflection portion in the area where the reflection portion is formed.

Further, according to a preferable aspect of the present invention, it is desirable that a plurality of the light emitting elements are provided. Thereby, the light from the light emitting element can be guided to the observation side more effectively.

Further, according to a preferable aspect of the present invention, it is desirable that the reflecting surface of the reflecting portion is formed into a substantially flat surface. Further, according to a preferred aspect of the present invention, it is desirable that the reflecting surface of the reflecting section is a concave mirror having a convex surface facing the first substrate side. As a result, it is possible to improve the reflection efficiency of the reflecting section.

Further, according to a preferred aspect of the present invention, it is preferable that the reflecting portion has a pyramidal shape having a bottom surface on the first substrate side. Further, according to a preferable aspect of the present invention, it is desirable that the reflection section has a conical shape having a bottom surface on the first substrate side. As a result, the light utilization efficiency can be improved regardless of the direction within one cell.

Further, according to a preferable aspect of the present invention, it is desirable that a plurality of the reflection portions are provided on the light emitting region of the light emitting element. Thereby, the light utilization efficiency can be further improved.

Further, according to a preferable aspect of the present invention, it is desirable that only one reflection portion is provided on the light emitting region of the light emitting element. Thereby, the reflecting portion can be easily manufactured.

The present invention also provides an electronic device including the display panel described above. This makes it possible to provide an electronic device that can obtain a bright image and can observe the image well.

Further, according to the present invention, the transmissive substrate for transmitting light from the light emitting element forming the pixel of the display device and the surface of the transmissive substrate corresponding to the light emitting region of the light emitting element are provided, and the light emitting element is provided. A plurality of reflecting portions for reflecting the light from the element to the observation side, the reflecting portion, with respect to the interface of the transparent substrate through which the light from the light emitting element is transmitted, a critical angle that causes total reflection. It is possible to provide a display panel reflection plate having an inclination angle such that light from the light emitting element that is incident beyond is reflected by the reflection portion and the reflected light is incident on the interface at a critical angle or less. . This allows
By applying it to the existing substrate on which the light emitting element is formed, the light utilization efficiency can be easily improved.

[0022]

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. As shown in FIG. 1, an organic EL element display 100 includes an organic EL element 1 that forms pixels of a display device.
10 and a plurality of reflecting portions 120 that are provided in the light emitting region 101 of the organic EL element 110 and that reflect the light from the organic EL element 110 to the observation side.

Further, in FIG. 1, the structure of the other cells is the same, and therefore, the structure of the organic EL element 110 shows only one cell among a plurality of pixels. Further, a second substrate 140 made of transparent glass is provided so as to overlap the first substrate 130. A transparent adhesive layer 150 is provided between the first substrate 130 and the second substrate 140.

The reflection part 120 is formed on the light emitting region 101 of the organic EL element 110. FIG. 2 is a diagram showing a partial configuration of the cross section of the present embodiment. The reflection part 120 reflects light from the organic EL element 110, which is incident on the glass surface 140a through which the light from the light emitting region 101 is transmitted, at an angle exceeding a critical angle causing total reflection, and reflects the reflected light. It has a reflection plate angle θ such that it enters the glass surface 140a at less than the critical angle.

Next, the reflection plate angle θ of this reflection surface 120a.
The optimum value of will be described. As shown in FIG. 2, the width of the light emitting region 101 is a, the width of the reflection part 120 (half of the total width) is b, and the height of the reflection part 120 is h. Figure 3
It is a figure which shows the result of having optimized the light emission area | region width a: reflective part width b: reflective part height h. Note that here, a = 1,
b and h are shown by the ratio.

The following (1) and (2) are obtained based on the result of FIG. (1) Total area (a + 2 × b) necessary to obtain brightness equivalent to that of an organic EL element without the reflective surface 120a
The ratio of ² to the light emitting region area of the organic EL element having no reflective surface 120a (hereinafter referred to as "required occupied area"), (2) Brightness equivalent to that of an organic EL element having no reflective surface 120a The ratio of the total area a ² required to obtain the desired height to the area of the light emitting region of the organic EL element having no reflective surface 120a (hereinafter referred to as “light emitting area ratio”).

FIG. 4 is a diagram showing the required occupying area and the light emitting area ratio using the reflector angle θ as a parameter. FIG. 5 shows a result of optimizing the reflector plate angle θ based on the results of FIGS. 3 and 4. As optimization conditions, it is desirable that the total light emitting area is small and the required occupied area is small.

Power consumption can be reduced by reducing the total light emitting area ratio. Further, by reducing the required occupying area, it is possible to increase the number of light emitting portions and improve the brightness. Further, the same occupancy area as the conventional one or less can be obtained with the same brightness as the conventional one. Moreover, it requires few design changes.

From FIG. 5, when the reflection plate angle θ = 75 °, the light emitting region width a: the reflection portion width b: the reflection portion height h = 1:
It becomes 0.43: 1.60. At this time, the required occupied area is 1.25 times, and the light emitting area ratio is 36%. For example, consider a case where the size of one cell of the organic EL element having no reflective surface 120a is 140 μm × 50 μm as shown in FIG. In this case, for the organic EL element having the reflection surface 120a, as shown in FIG. 6B, a small organic EL element 110 may be arranged in parallel within a range of 56 μm × 157 μm.

(Second Embodiment) FIG. 7 is a view showing the arrangement of an organic EL element display 200 including an organic EL element reflection plate 210 according to the second embodiment. This is different from the first embodiment in that the organic EL element reflection plate 210 is provided on the second substrate 140 side of the glass. Since other configurations are the same as those in the first embodiment, the same portions are denoted by the same reference numerals, and duplicated description will be omitted.

The organic EL element reflection plate 210 has a V-shaped groove. The organic EL element reflection plate 210 having such a shape can be easily formed on the second substrate 140 side of glass. In addition, the organic EL element display 200 can be easily manufactured by simply adhering it to the existing first substrate 130 on which the organic EL element is formed.

(Third Embodiment) FIG. 8 is a diagram showing the structure of an organic EL element display 300 according to the third embodiment. Different from the first embodiment, the partition wall portion 31 is provided in a portion of the light emitting region 101 which is shielded below the reflection portion 120.
0 is formed. Since other configurations are the same as those in the first embodiment, the same reference numerals are given to the same portions,
A duplicate description will be omitted.

The partition 310 is made of SiO ₂ or the like.
The partition part 310 and the reflection part 120 can be formed at the same time. Alternatively, the reflective part 120 may be formed separately after the partition part 310 is formed. With such a configuration, the organic EL element 110 does not have to be formed in a region that is shielded by the reflection section 120. As a result, power saving can be achieved.

(Fourth Embodiment) FIG. 9 is a diagram showing the structure of an organic EL element display 400 according to the fourth embodiment. Unlike the above-described third embodiment, the reflecting surface 410a of the reflecting section 410 is configured by a concave mirror having a convex surface facing the first substrate 130 side. Since other configurations are the same as those in the first embodiment, the same portions are denoted by the same reference numerals, and duplicated description will be omitted. Thereby, the light from the organic EL element 110 can be more efficiently reflected to the glass second substrate 140 side.

(Fifth Embodiment) FIG. 10 is a view showing the arrangement of an organic EL element display 500 according to the fifth embodiment. Unlike each of the above-described embodiments, the reflection part 510 has a pyramid shape having a bottom surface on the first substrate 130 side. In addition,
In FIG. 10, a plurality of pyramidal reflecting portions 510 are provided on the organic EL element 110 which is one cell, but the present invention is not limited to this, and a single large reflecting portion 510 is provided in one cell. It may be provided.

(Sixth Embodiment) FIG. 11 is a view showing the arrangement of an organic EL element display 600 according to the sixth embodiment. Unlike the fifth embodiment, the reflection unit 610 is
The conical shape has a bottom surface on the first substrate 130 side. Note that in FIG. 11, the organic EL element 110, which is one cell,
Although a plurality of conical reflecting portions 610 are provided above, the present invention is not limited to this, and a single large reflecting portion 610 may be provided in one cell.

Further, in each of the above embodiments, the configuration relating to one cell is shown, but the present invention is not limited to this, and a plurality of cells having the configurations described in each of the above embodiments may be arranged in parallel. Furthermore, although the organic EL element has been described, it is needless to say that it is suitable for other display elements, particularly a self-luminous element and a liquid crystal display element.

(Seventh Embodiment) FIGS. 12 (a), 12 (b),
Each of (c) is an example of an electronic device including the display panel according to the present invention. FIG. 12A is a perspective view showing an example of a mobile phone. Reference numeral 1000 denotes a mobile phone main body, of which 1001 is a liquid crystal display device using the display panel of the present invention. FIG. 12B is a perspective view showing an example of a wristwatch type electronic device. Reference numeral 1100 denotes a watch body, and 1001 is a liquid crystal display device using the display panel of the present invention. FIG. 12C is a perspective view showing an example of a portable information processing device such as a word processor and a personal computer. In the figure, reference numeral 1200 denotes an information processing apparatus, and 1202 an input unit such as a keyboard, 1204.
Is an information processing device main body, and 1206 is a liquid crystal display device using the display panel of the present invention.

[0039]

As described above, according to the present invention,
It is possible to obtain a reflector for a display panel, a display panel, and an electronic device that can increase the light utilization efficiency and obtain a bright image.

[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 diagram showing a cross-sectional configuration of the organic EL element display according to the first embodiment.

FIG. 3 is a diagram showing a result obtained by optimizing a light emitting region width a: a reflection portion width b: a reflection portion height h.

FIG. 4 is a diagram showing a required occupying area and a light emitting area ratio using a reflector angle θ as a parameter.

FIG. 5 is a diagram showing a result of optimizing a reflector angle θ.

FIG. 6 is a diagram showing a comparison of cell sizes.

FIG. 7 is a perspective view showing a schematic configuration of an organic EL element display according to a second embodiment of the present invention.

FIG. 8 is a perspective view showing a schematic configuration of an organic EL element display according to a third embodiment of the present invention.

FIG. 9 is a perspective view showing a schematic configuration of an organic EL element display according to a fourth embodiment of the present invention.

FIG. 10 is a perspective view showing a schematic configuration of an organic EL element display according to a fifth embodiment of the present invention.

FIG. 11 is a perspective view showing a schematic configuration of an organic EL element display according to a sixth embodiment of the present invention.

12A, 12B, and 12C are external views showing examples of electronic devices using the display panel of the present invention.

13A and 13B are diagrams showing a configuration of a conventional organic EL element display.

[Explanation of symbols]

100, 200, 300, 400, 500, 600
Organic EL element display 110 Organic EL element 101 Light emitting area section 120, 210, 410, 510, 610 Reflecting section 120a, 410a Reflecting surface 130 First substrate 140 Second substrate 140a Glass surface 150 Adhesive layer 310 Partition wall 1000 Cell phone main body 1100 Clock body 1200 Information processing device

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Claims (14)

[Claims] 1. A light emitting element forming a pixel of a display device, and a plurality of reflecting portions provided in at least a light emitting region of the light emitting element for reflecting light from the light emitting element to an observation side. A display panel having: 2. The reflecting section reflects, at the reflecting section, light from the light emitting element which is incident on an interface of a transparent medium through which light of the light emitting element is transmitted and which exceeds a critical angle causing total reflection, The display panel according to claim 1, wherein the display panel has an inclination angle such that the reflected light is incident on the interface at a critical angle or less. 3. A first device having a plurality of light emitting elements provided on a surface thereof.
A transparent substrate, a transparent second substrate overlaid on the first substrate, and a transparent medium layer provided between the first substrate and the second substrate; The display panel according to claim 2, wherein the display panel is formed on the light emitting region of the light emitting element or on a surface of the second substrate facing the light emitting element. 4. The display panel according to claim 3, wherein the transparent medium layer is an adhesive layer. 5. The display panel according to claim 3, further comprising a partition wall portion provided between the light emitting element and the reflection portion. 6. The display panel according to claim 3, wherein a plurality of the light emitting elements are provided. 7. The display panel according to claim 2, wherein the reflecting surface of the reflecting portion is formed of a substantially flat surface. 8. The display panel according to claim 2, wherein the reflecting surface of the reflecting portion is a concave mirror having a convex surface facing the first substrate side. 9. The display panel according to claim 2, wherein the reflection part has a pyramid shape having a bottom surface on the first substrate side. 10. The display panel according to claim 2, wherein the reflection portion has a conical shape having a bottom surface on the first substrate side. 11. The display panel according to claim 9, wherein a plurality of the reflection parts are provided on the light emitting area of the light emitting element. 12. The display panel according to claim 9, wherein only one of the reflecting portion is provided on the light emitting area of the light emitting element. 13. An electronic device comprising the display panel according to claim 1. Description: 14. A transparent substrate that transmits light from a light emitting element forming a pixel of a display device, and a surface of the transparent substrate corresponding to a light emitting region of the light emitting element, the light from the light emitting element being observed. A plurality of reflecting portions for reflecting the light toward the side, wherein the reflecting portions are incident on the interface of the transparent substrate through which the light from the light emitting element is transmitted, the incident light exceeding a critical angle causing total reflection. A reflection plate for a display panel, which has an inclination angle such that light from an element is reflected by the reflection portion and the reflected light is incident on the interface at a angle less than a critical angle.