JPH11339959A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device capable of improving display quality at the time of non-lighting while preventing the visual recognition of the fluorescent color of a color converting layer and of improving a contrast between picture elements at the time of selective lighting. SOLUTION: A transparent electrode 12, an organic EL layer 13, a back surface electrode 14 are formed on the back surface of a first transparent board 11 so as to form a light emitting part. A first black layer 16 is formed on the back surface of a second transparent board 15, and an annular opening part 16A is formed at a part corresponding to the light emitting part, and a color converting layer 17 is arranged on the back surface of a black mask 16B surrounded by the opening part 16A. A second black layer 18 is formed on the back surface of the first black layer 17, and the light emitting part and the color converting layer 17 are arranged opposite to each other through a space 18A formed in the second black layer 18. With this structure, intrusion of the external light into the color converting layer 17 is shielded by the black mask 16B, and the visual recognition of the fluorescent color of the color converting layer is prevented so as to improve the dignity of display at the time of non-lighting, and a contrast between picture elements at the time of selective lighting can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device,
More specifically, electroluminescence (hereinafter referred to as E
L) and a color conversion film.

[0002]

2. Description of the Related Art In recent years, a display device using an organic EL material for a light emitting layer has been receiving attention. As such a display device, for example, as shown in FIG. 11, a color conversion layer made of a phosphor is disposed between a light emitting layer and an observer, and light generated in the light emitting layer is incident on the color conversion layer. There is one that converts the light into light of a different wavelength range and expresses a color different from the light emitted from the light emitting layer. In this conventional display device, as shown in FIG. 1, one surface (the lower surface in the figure) of the first glass substrate 1
A transparent electrode 2, a light emitting layer 3, and a back electrode 4 are sequentially formed,
A black mask layer 6 is formed on the back surface of a second glass substrate 5 disposed on the front surface (upper surface in the drawing) of the first glass substrate 1, and a color conversion layer 7 is disposed and formed in an opening of the black mask layer 6. Have been. The first glass substrate 1 side and the second
The glass substrate 5 side is bonded with an adhesive or the like. The color conversion layer 7 is a phosphor having a fluorescent component on a longer wavelength side with light generated from the light emitting layer 3 as an excitation component. For example, the emission wavelength of the light emitting layer 3 is set in a blue wavelength region. Phosphors having fluorescence characteristics that can be effectively excited in a wavelength region are used.

[0003]

However, in the display device having the above-mentioned conventional structure, since the visible wavelength region is included in the excitation wavelength region of the color conversion layer 7, the color conversion layer 7 emits fluorescent light even by external light. As a result, there is a problem that the fluorescent color and the pattern shape of the color conversion layer 7 are recognized irrespective of non-lighting. In order to avoid this problem, a wavelength selection that efficiently absorbs the light in the blue region, which is the excitation wavelength region, and transmits the fluorescent wavelength region after color conversion is provided at a position between the color conversion layer 7 and the observer. It is conceivable to arrange a layer having a band (for example, a color filter). However, since many phosphors have an excitation wavelength band on the short wavelength side immediately adjacent to the fluorescence wavelength band, the fluorescence contained in the external light is It was difficult to completely block the body's excitation wavelength range. Further, in the conventional display device, since the color conversion layer 7 is provided as a light transmission path, the blue color component, which is the emission color of the light emitting layer 3 that cannot be sufficiently absorbed by the color conversion layer 7, is transmitted. Therefore, there is a problem that the color tone becomes bluish even after the color conversion and the color purity is not sufficient.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a display device which can improve the display quality at the time of non-lighting without visually recognizing the fluorescent color of the color conversion layer and improve the contrast ratio between pixels at the time of selective lighting. And

[0005]

According to the first aspect of the present invention,
In the display device, a color conversion layer is disposed in front of a light emitting portion having a light emitting layer sandwiched between electrodes, and a light shielding layer is disposed in front of the color conversion layer, and is converted by the color conversion layer. A light emission area for emitting light is arranged adjacent to the light shielding layer.

According to the first aspect of the present invention, the light emitted from the light emitting section enters the color conversion layer to excite the color conversion layer, and emits light having different wavelength bands. The light emitted from the color conversion layer is guided so as to be emitted forward from a light emission area adjacent to the light shielding layer. The light shielding layer prevents external light from being incident on the color conversion layer and prevents the color conversion layer from generating fluorescence due to external light.

According to a second aspect of the present invention, in the display device according to the first aspect, the light shielding layer is made of a black material containing a black dye. According to a third aspect of the present invention, in the display device according to the first aspect, the light shielding layer is formed of a light reflecting plate.

According to a fourth aspect of the present invention, in the display device according to any one of the first to third aspects, the light emitting portion is formed on a back side of the first transparent substrate, and the light shielding layer is Second
The color conversion layer is formed on the back surface of the light shielding layer, while being formed on the back surface of the transparent substrate.

According to the fourth aspect of the present invention, the light converted by the color conversion layer has a longer wavelength range than the light emitted from the light emitting portion, and therefore has a higher reflectance on the first transparent substrate surface than the light from the light emitting portion. Therefore, the light emitted from the color conversion layer side can be efficiently reflected and guided to the light emission region.

According to a fifth aspect of the present invention, in the display device according to any one of the first to fourth aspects, a light propagation layer is disposed in front of the light shielding layer. .

According to the fifth aspect of the present invention, the light guided to the periphery of the light shielding layer propagates through the light propagation layer, so that the area of the light emitting pixel region can be substantially increased.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of a display device according to the present invention will be described below based on embodiments shown in the drawings. (Embodiment 1) FIGS. 1 and 2 show Embodiment 1 of a display device according to the present invention. In the first embodiment, the present invention is applied to a display device that performs dot display in which a transparent electrode and a back electrode sandwiching a light emitting layer are formed in an XY matrix.

As shown in FIG. 1, the display device 10 according to the present embodiment has a structure in which the first transparent substrate 11 and the second transparent substrate 15 are bonded to each other. On the first transparent substrate 11 side, a plurality of transparent electrodes 12 made of ITO (indium tin oxide) are formed in a stripe shape on the back surface (lower surface in the figure) of the first transparent substrate 11 made of, for example, glass so as to be parallel to each other. ing. Further, a plurality of organic EL layers 13 as light emitting layers are formed in parallel with each other so as to cross the transparent electrodes 12. A back electrode 14 made of, for example, Mg-In is laminated on the organic EL layer 13 in the same pattern as the organic EL layer 13. Although not shown, the organic EL layer 1
As 3, a structure in which three layers of an organic hole transport layer, an organic light emitting layer, and an organic electron transport layer are sequentially laminated on the surface of the transparent electrode 12 can be adopted. Examples of the organic hole transport layer include N, N'-di (α-naphthyl) -N, N'-diphenyl-
1,1'-biphenyl-4,4'-diamine (referred to as α-NPD)
It becomes. As the organic light emitting layer, 4,4′-bis (2,2′-
Diphenylvinylene) biphenyl (DPVBi)
Is co-evaporated with 96 wt% and 4,4′-bis (2-carbazolevinylene) biphenyl (referred to as BCzVBi) with 4 wt%. Further, as the organic electron transporting layer, tris (8-hydroxyquinoline) aluminum (Alq3
).

On the second transparent substrate 15 side, a thin first black layer 16 containing a black dye or a black pigment is formed on the back surface (the lower surface in the figure) of the second transparent substrate 15 made of, for example, glass. In addition, an annular opening 16A is formed in the first black layer 16 corresponding to the pixel portion (the portion where the transparent electrode 12 and the back electrode 14 intersect) on the first transparent substrate 11 side. A circular black mask 16B is formed so as to be surrounded by the opening 16A. On the back surface of the black mask 16B, a color conversion layer 17 having a smaller diameter than the black mask 16B is formed concentrically. Further, a second black layer 18 having a relatively large thickness is formed on the back surface of the first black layer 16 other than the black mask 16B. That is, the color conversion layer 17 and the black mask 16B are accommodated in the space 18A formed by the second black layer 18. In the present embodiment,
The second black layer 18 is not formed near the periphery of the first black layer 16 facing the opening 16A, and the inner diameter of the space 18A is set to be longer than the outer diameter of the opening 16A.

The display device 10 of the present embodiment is configured by bonding a second black layer 18 formed on the second transparent substrate 15 side to the surface (the upper surface in the figure) of the first transparent substrate 11 with an adhesive. ing. Here, the portion (light emitting portion) where the transparent electrode 12 and the back electrode 14 formed on the first transparent substrate 11 intersect is located at the center of the color conversion layer 17 formed on the second transparent substrate 15 via the space 18A. Is set to face. In the present embodiment, the color conversion layer 17 is set to have a larger area than the light emitting portion, and the black mask 16B is set to have a larger area than the color light emitting layer 17.
For this reason, when viewed from the front side of the second transparent substrate 15, the color conversion layer 17 and the light emitting portion are not visible due to the presence of the black mask 16B as shown in FIG. As described above, in the display device 10 according to the embodiment, the external light is directly incident on the color conversion layer 17 by the black mask 16B.
Has a structure to block.

Next, the operation of the display device 10 of the present embodiment will be described. In the present embodiment, as shown in FIG.
The organic EL layer 13 sandwiched between the transparent electrode 12 and the back electrode 14 at a portion where the transparent electrode 12 and the back electrode 14 intersect generates, for example, blue light when an electric field is applied to both the electrodes. When this light enters the color conversion layer 17, the color conversion layer 17 is excited and emits light in a wavelength band longer than the incident light, for example, light such as green or red. As the color conversion layer 17, a layer that generates light in a green wavelength band or a layer that generates light in a red wavelength band is set and arranged in advance according to the color arrangement of dots. The newly generated converted light is in space 1 as shown in FIG.
The light is reflected by the inner wall surrounding 8A, and is emitted toward the observer from the annular opening 16A formed in the first black layer 16. In addition, even if external light is irradiated from the observer side, since the black mask 16B can prevent the external light from directly radiating to the color conversion layer 17, no fluorescence is generated from the color conversion layer 17 due to the external light. This dot portion is not visually recognized by an observer when the light is not lit. For this reason, the display quality when the display device 10 is not driven is improved, and the contrast ratio between pixels during selective lighting is improved. Further, in the present embodiment, the opening 16A of the first black layer 16 determines the pixel area. However, the area of the light emitting section may be smaller than this pixel area. The width can be reduced, and the degree of freedom in design can be improved. In addition, if the light emitted from the light emitting unit is not emitted from the opening 16A, it is reflected by the black mask 16B and the like and continues to travel in the space 18A. Therefore, the possibility of repeating the light entering the color conversion layer 17 a plurality of times increases. . For example, when blue light is emitted from the light emitting unit, the rate of conversion of the blue light to light in a long wavelength band by repeating incidence and emission to the color conversion layer 17 is increased. Since the wavelength-converted light has a longer wavelength range than the emission wavelength of the organic EL layer 13, it is more likely to be reflected at the interface with the first transparent substrate 11 than the light of the organic EL layer 13. Since light is easily emitted from the opening 16A,
The problem that the light emitted from A to the observer side becomes bluish can be solved.

In the present embodiment, the second black layer 18
However, by forming a material layer having high light reflectivity in place of the second black layer 18, it is possible to increase the efficiency of light emission from the opening 16A.

(Embodiment 2) FIGS. 3 and 4 show Embodiment 2 of the display device according to the present invention. The display device 10 of the present embodiment is configured such that the first transparent substrate 11 side and the second transparent substrate 15 side are bonded to each other, as in the first embodiment. The configuration on the first transparent substrate 11 side is as follows:
This is the same as Embodiment 1 described above.

As shown in FIG. 3, on the back surface (lower surface in the figure) of the second transparent substrate 15, a circular area having a larger area than the light emitting portion is provided at a position corresponding to the light emitting portion on the first transparent substrate 11 side. Are formed. This light propagation layer 19
The peripheral side surface is formed in a tapered shape, and has a trapezoidal cross section as shown in FIG. The light propagation layer 1
9 is a method in which an inorganic material having a high light transmittance and a refractive index higher than that of the second transparent substrate 15 such as ITO or SiO ₂ is formed by chemical etching or a synthetic resin such as an acrylic resin is formed by photolithography. It can be formed using.

On the back surface of the light propagation layer 19, a reflection layer 20A having a diameter slightly shorter than that of the light propagation layer 19 is formed concentrically, and the reflection layer 20A is formed in a region other than the region where the light propagation layer 19 is formed. The layer 20B is formed. A color conversion layer 17 having a smaller diameter than the reflection layer 20A is formed concentrically on the back surface of the reflection layer 20A.

Further, a thick black layer 21 is formed on the back surface of the reflection layer 20B. As a result, the structure is such that the color conversion layer 17, the reflection layer 20A, and the light propagation layer 19 are accommodated in the space 21A surrounded by the black layer 21. In the present embodiment, the black layer 21 is not formed near the periphery of the reflection layer 20B facing the light propagation layer 19, and the inner diameter of the space 21A is set to be longer than the outer diameter of the light propagation layer 19. .

The display device 10 of the present embodiment is configured such that a black layer 21 formed on the second transparent substrate 15 side is adhered to the surface (the upper surface in the figure) of the first transparent substrate 11 with an adhesive. . Here, a portion where the transparent electrode 12 formed on the first transparent substrate 11 and the back electrode 14 intersect (light emitting portion)
Is set to face the center of the color conversion layer 17 formed on the second transparent substrate 15 via the space 21A.
As described above, in the present embodiment, the area of the color conversion layer 17 is set to be larger than that of the light emitting unit, and the area of the reflection layer 20A is set to be larger than that of the color light emitting layer 17. For this reason, when viewed by the observer from the front side of the second transparent substrate 15, the color conversion layer 17 and the light emitting portion are not visible because of the reflection layer 20A as shown in FIG. Thus, in the display device 10 of the present embodiment, the external light is
7 has a structure in which the reflection layer 20A blocks the light from entering directly.

Next, the operation of the display device 10 of the present embodiment will be described. In the present embodiment, the predetermined transparent electrode 12 and the back electrode 14 on the first transparent substrate 11 side are selected, and an electric field is applied between the two electrodes. Generates blue light, for example. When this light enters the color conversion layer 17, the color conversion layer 17
Are excited and emit light in a wavelength band longer than the incident light, for example, light such as green or red. As the color conversion layer 17, a layer that generates light in a green wavelength band or a layer that generates light in a red wavelength band in advance according to the color arrangement of dots is set.
Are located. The newly generated converted light is reflected by the reflection layers 20A and 20B and the inner wall of the space 21A as shown by an arrow in FIG. In the light propagation layer 19, the converted light that has entered has an effect of irregularly reflecting and propagating the converted light in the plane direction, so that the hatched portion shown in FIG. In addition, even if external light is applied to the display device 10 from the observer side, the external light can be prevented from being incident on the color conversion layer 17 by the reflection layer 20A. No dot is generated, and the dot portion is not visually recognized by an observer when it is not lit. Therefore, the first embodiment described above
Similarly to the above, the display quality when the display device 10 is not driven is improved, and the contrast ratio between pixels during selective lighting is improved. Note that other operations in the second embodiment include:
This is the same as Embodiment 1 described above.

Although the second embodiment has been described above, also in the second embodiment, by forming a material layer having high light reflectivity instead of the black layer 21, it is possible to increase the light emission efficiency. . Further, if the light diffusing plate 22 is arranged on the surface of the second transparent substrate 15 according to the second embodiment as in the first modification shown in FIG. 5, the uniformity of the brightness of the pixels can be improved. At the same time, the boundary between the opening of the reflective layer 20B and the light propagation layer 19 can be made less visible from the viewer side, and the display quality can be improved. further,
As in Modification Example 2 shown in FIG. 6, the first transparent substrate 11 has a surface on which a light-reflecting reflective layer 23 made of, for example, aluminum or the like, having an opening 23 </ b> A at a position corresponding to the light-emitting portion is provided. By doing so, it is possible to increase the light reflection efficiency and extract light efficiently. Modification 3 shown in FIG. 7 includes a space 21 </ b> A surrounded by the black layer 21.
For example, a modification 4 shown in FIG. 8 has a configuration in which a high refractive index material such as an acrylic resin is filled.
9 is applied to the surface of the first transparent substrate 11, and the modification 5 shown in FIG. 9 is such that a pressure-sensitive adhesive 25 having a high refractive index is applied to the entire surface of the first transparent substrate 11. Are attached, and any of the modifications can enhance the reflection efficiency of light at the interface with the first transparent substrate 11.
Further, in a sixth modification example shown in FIG. 10, a λ / 4 elliptically polarizing filter 26 is disposed on the surface of the second transparent substrate 15, and a linearly polarizing plate 27 is provided on the elliptically polarizing filter 26. Reflection of external light on the layer 20B can be suppressed. As a result, in the sixth modification, display visibility in a bright place can be improved. Note that the configuration of the elliptically polarizing filter 26 and the linear polarizing plate 27 can change the surface of the linear polarizing plate 27 to a substantially black color when light is not emitted, so that the contrast ratio is significantly improved. It is also possible to arrange a light diffusing plate on the viewer side of the linear polarizing plate 27.

[0025]

As is apparent from the above description, according to the present invention, the fluorescent color of the color conversion layer is not visually recognized.
It is possible to improve the display quality in non-lighting, improve the contrast ratio between pixels in selective lighting, and realize a display device capable of performing display with higher color purity.

[Brief description of the drawings]

FIG. 1 is a sectional view showing Embodiment 1 of a display device according to the present invention.

FIG. 2 is a plan view of the display device according to the first embodiment.

FIG. 3 is a sectional view showing Embodiment 2 of the display device according to the present invention.

FIG. 4 is a plan view of a display device according to a second embodiment.

FIG. 5 is a sectional view showing a first modification of the second embodiment.

FIG. 6 is a sectional view showing a modification 2 of the second embodiment.

FIG. 7 is a sectional view showing a third modification of the second embodiment.

FIG. 8 is a sectional view showing a fourth modification of the second embodiment.

FIG. 9 is a sectional view showing Modification Example 5 of Embodiment 2.

FIG. 10 is a sectional view showing a modification 6 of the second embodiment.

FIG. 11 is a cross-sectional view of a conventional display device.

[Explanation of symbols]

 Reference Signs List 10 display device 11 first transparent substrate 12 transparent electrode 13 organic EL layer 14 back electrode 15 second transparent substrate 16 first black layer 16A opening 16B black mask 17 color conversion layer 18 first black layer 18A space 19 light propagation layer 20A Reflective layer 21 Black layer 22 Diffusion plate 23 Reflective layer 24 Light propagation layer 26 Elliptical filter 27 Linear polarizer

Claims (5)

[Claims] 1. A color conversion layer is disposed in front of a light emitting portion having a light emitting layer sandwiched between electrodes, a light shielding layer is disposed in front of the color conversion layer, and light converted by the color conversion layer is provided. A light emitting area for emitting light is disposed adjacent to the light shielding layer. 2. The display device according to claim 1, wherein the light shielding layer is made of a black material containing a black dye. 3. The display device according to claim 1, wherein the light shielding layer is formed of a light reflecting plate. 4. The light emitting section is formed on the back side of the first transparent substrate, the light shielding layer is formed on the back side of the second transparent substrate, and the color conversion layer is formed on the back side of the light shielding layer. The display device according to claim 1, wherein the display is performed. 5. The display device according to claim 1, wherein a light propagation layer is disposed in front of the light shielding layer.