JP4032956B2 - Self-luminous element, display panel, display device, and self-luminous element manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a self-luminous element such as organic electroluminescence (organic EL), and a display panel.
[0002]
[Prior art]
In recent years, as a self-luminous flat panel display (FPD), a display panel using an organic EL element and a display panel using a plasma display panel (PDP) have been actively developed. These display panels have a configuration in which a light emitting layer is disposed between an anode layer and a cathode layer. In a display panel, a self-luminous element is caused to emit light by applying a voltage between electrodes, and characters and images are recognized by viewing the light emitting surface through a transparent medium or a transparent panel having a refractive index greater than 1. Can do.
[0003]
However, since the light emitted from the light emitting surface of the self-luminous element is emitted, that is, emitted at almost all angles, the incident angle is greater than the critical angle with respect to the interface between the transparent medium and the outside (or air). There arises a problem that light is totally reflected at the interface and confined in the display panel. For example, in an organic EL element which is one of self-luminous elements, it is said that only about 20% to 30% of light can be taken out of the display panel.
[0004]
In order to solve such problems related to light utilization efficiency or light extraction efficiency, a slope structure is created inside the panel so that light having a radiation angle greater than the critical angle is converted to less than the critical angle. It is disclosed that the light extraction efficiency is increased by generating reflection and refraction on the slope of the light. In particular, in Japanese Patent Laid-Open No. 10-189251, in a top emission type display panel in which light is emitted from a transparent panel side covering a light emitting layer formed on a base substrate, a wedge-shaped reflecting member is provided around the light emitting layer. An arrangement is disclosed in which a reflective structure is built in. Japanese Laid-Open Patent Publication No. 2001-332388 discloses a configuration in which slopes are formed on an anode and a cathode sandwiching a light emitting layer in a bottom emission type display panel in which light is emitted from the base substrate side on which the light emitting layer is formed. Has been.
[0005]
[Patent Document 1]
JP-A-10-189251
[Patent Document 2]
JP 2001-332388 A
[0006]
[Problems to be solved by the invention]
However, the configuration that prevents the total reflection at the interface by changing the angle of the light emitted from the light-emitting layer on the inclined surface tends to be thick, which may be a limitation when realizing a very thin flat panel display. There is. In order to increase the light extraction efficiency from the display panel, it is necessary to change the angle of light incident on the interface between the transparent panel and the outside world at an angle greater than the critical angle, so that such light must be Alternatively, it is necessary to design such that most of the light is incident on the slope. That is, in order to reduce the light incident at the critical angle from the light emitting layer to the interface of the transparent panel, it is necessary to form a high slope, and as a result, the transparent panel becomes thick. For this reason, to increase the light extraction efficiency, a thick transparent panel must be employed, and the entire display panel cannot be thinned. On the other hand, if the transparent panel is made thin, the entire display panel can be made thin, but light incident on the interface at a critical angle or more increases, so that the light extraction efficiency decreases.
[0007]
In view of the above, an object of the present invention is to provide a self-luminous element, a display panel, and a method for manufacturing the self-luminous element that can simultaneously achieve the conflicting demands of thinning the display panel and improving the light extraction efficiency. It is said. It is another object of the present invention to provide a display device that can display a very thin and bright image by using the display panel of the present invention.
[0008]
[Means for Solving the Problems]
For this reason, in the present invention, the light emitted from the light emitting layer at a critical angle or more with respect to the interface is not prevented from being totally reflected at the interface, but is used for the reflection layer on the opposite side. Is formed and multiple reflections are performed, so that the light totally reflected at the interface is led to an angle conversion unit provided around the light emitting layer, where the angle is converted. That is, the self-luminous element of the present invention is a protective layer that is disposed between electrodes and that emits light by a voltage applied between the electrodes, covers the emission side of the light emitting layer, and forms an interface with the outside. A protective layer having a thickness such that light emitted from the light emitting layer is totally reflected at an interface within the area of the light emitting layer at least once; a reflective layer covering the opposite side of the protective layer with respect to the light emitting layer; There is an angle conversion unit that changes the direction of light emitted from the light emitting layer and propagates through the protective layer to make it less than the critical angle with respect to the interface.
[0009]
In the self-luminous element of the present invention, a thin protective layer is employed so that the light emitted from the light emitting layer is totally reflected at least once. Therefore, it is possible to make the whole self-luminous element thin. The same applies to a display panel provided with a plurality of light emitting layers. By positively utilizing total reflection at the interface, the light extraction efficiency can be improved and the display panel can be thinly packed. On the other hand, light emitted above the critical angle with respect to the interface of the protective layer reaches the angle conversion part arranged around the light emitting layer by multiple reflection between the interface and the reflective layer located on the opposite side of the interface. The angle is converted and output to the outside world. And since the protective layer may be thin, it can be made thinner than the slope structure which forms an angle conversion part, for example, the bank and protrusion which are described below. With such a configuration, light propagated around the light emitting layer due to multiple reflection is always extracted after the angle is converted by the angle conversion unit, so that the light extraction efficiency is also improved. In addition, a high slope serving as an angle conversion portion is not necessary, and a bright display panel can be provided at low cost by eliminating the trouble of forming the slope structure.
[0010]
Therefore, it is possible to provide a self-luminous element and a display panel that can satisfy the two contradictory requirements of making the self-luminous element or display panel thin and improving the light extraction efficiency. In particular, in a self-luminous element or display panel using an organic electroluminescence light emitting layer, the light extraction efficiency is at most about 20 to 30%, so the present invention is very effective. Therefore, a display device having the display panel of the present invention and a driving device that drives the light emitting layer of the display panel to display an image can be provided in a very thin size and can display a bright image.
[0011]
One of the angle conversion units that change the angle of light propagating through the protective layer to make it less than the critical angle with respect to the interface is a reflecting surface that is inclined so that the exit side becomes wider. Further, the angle conversion unit may be a refracting surface that is inclined so that the exit side becomes narrow. In any case, a slope structure is required.
[0012]
If the slope surrounding the light emitting layer is high, if the slope is constant, the distance between the adjacent light emitting layers becomes longer when the slope is higher, and the size of the display panel that outputs an image with high resolution becomes larger. Therefore, a display device that employs the display panel also becomes large. On the other hand, when the slope is low (angle conversion unit), the distance between adjacent light emitting layers is shortened, and the display panel and the display device for displaying an image with high resolution can be made compact.
[0013]
In addition, in a display panel in which a planar area including a light emitting layer and a slope corresponds to one pixel, a slope (angle conversion unit) is an area occupied by the pixel with respect to a light emitting area per pixel (light emitting surface of the light emitting layer). Is also included. Therefore, the area of the angle conversion unit can be reduced according to the present invention, so that the area of the pixel can be reduced, and light having the same light emission amount can be emitted from the pixel having a small area. Therefore, the brightness of the display panel is also improved. Therefore, according to the present invention, there is an advantage that the luminance can be increased by reducing the pixels, and a very bright image or character can be displayed.
[0014]
In the self-luminous element and the display panel, one of the electrodes arranged so as to sandwich the light emitting layer, that is, the electrode opposite to the emission side can be used as the reflective layer. This eliminates the need for a dedicated reflective layer and can provide a thinner self-luminous element and display panel.
[0015]
In the self-luminous element and the display panel of the present invention, it is desirable to form a bank protruding to the emission side in order to separate the light emitting layer from other light emitting layers, and to use the inner surface of the bank as an angle conversion section. The self-light-emitting element and the display panel of the present invention may have a configuration in which a sheet-like or panel-like member in which an angle conversion portion is formed is attached as a protective layer, but there is a gap between the light-emitting layer and the protective layer. Is likely to occur and leakage light (crosstalk) is likely to occur. Further, when the protective layer is pasted, bubbles and the like are likely to enter at the stage of pasting, and light may be scattered by the bubbles, which may hinder the use efficiency. Furthermore, it is considered difficult to manufacture so as not to generate crosstalk or enter bubbles.
[0016]
On the other hand, when the inner surface of the bank formed around the light emitting layer is used as an angle conversion portion, when the protective layer is formed in a region surrounded by the bank, the protective layer is almost adhered to the light emitting layer, or the protection The distance between the layer and the light emitting layer can be minimized, and the occurrence of crosstalk can be suppressed. In addition, since a protective layer may be formed in a region surrounded by the bank, it can be formed by a method such as applying the protective layer to the region, and bubbles may enter at the stage of forming the protective layer. Can also be prevented. Furthermore, with this structure, the thickness of the protective layer is absorbed by the thickness of the bank, that is, the thickness of the protective layer does not affect the thickness of the element and the display panel, so that a thinner self-luminous element and display panel can be provided. .
[0017]
Therefore, a light emitting layer that is disposed between the electrodes and emits light by a voltage applied between the electrodes, and a protective layer that covers the emission side of the light emitting layer and forms an interface with the outside, where light emitted from the light emitting layer The light emitting layer is emitted from the light emitting layer around the light emitting layer, the protective layer having a thickness that allows total reflection at least once at the interface within the area of the light emitting layer, the reflective layer covering the opposite side of the light emitting layer to the protective layer A self-luminous element having an angle conversion unit that changes the direction of light propagating in the protective layer to make it less than a critical angle with respect to the interface, In order to separate from the layer, the method has a bank protruding to the exit side, the inner surface of the bank is used as an angle conversion unit, and a method of forming a protective layer in a region surrounded by the bank, A self-luminous element having a high light utilization efficiency can be manufactured.
[0018]
It is also possible to form a protrusion made of an insulating material protruding from the bank to the emission side, and to use the inner surface of this protrusion as an angle conversion portion. Then, a protective layer is formed in a region surrounded by the protrusions. However, compared to a configuration in which the inner surface of the bank is an angle conversion unit, crosstalk may occur in the bank portion, and therefore, a configuration in which the inner surface of the bank is an angle conversion unit is most preferable. On the other hand, in the configuration in which the inner surface of the bank is used as the angle conversion unit, when the film such as aluminum is formed on the inner surface of the bank to form the angle conversion unit, the electrode disposed so as to sandwich the light emitting layer is There is a possibility of being short-circuited. Therefore, since it is necessary to form an insulating film or the like, considering the ease of manufacturing the display panel, a configuration in which protrusions are formed on the bank and the inner surface thereof is an angle conversion portion is considered suitable. It is done.
[0019]
A self-luminous element that uses an insulating protrusion formed on the bank as an angle conversion part insulates the protrusion protruding to the emission side from the bank protruding to the emission side in order to separate the light emitting layer from other light emitting layers. It can be manufactured by a method that includes a step of forming a material and forming the inner surface of the protrusion as an angle conversion portion and a step of forming a protective layer in a region surrounded by the protrusion.
[0020]
The present invention can be applied to any self-luminous light emitting element, that is, a self-luminous element or a display panel. Therefore, the present invention can be applied to a display body or a display panel using PDP, light emitting diode, inorganic EL, organic EL, field emission, or the like. In particular, a display body (or a self-luminous element) using an organic EL element whose light emitting layer is an organic electroluminescent light emitting layer, or a display panel has very low light extraction efficiency, and thus the present invention is very useful.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 shows a mobile phone as a display device on which a display panel according to the present invention is mounted. In the cellular phone 1 of this example, a display panel using an organic EL element which is a self-luminous element is employed as a display panel 10a on which data is displayed, and light is emitted from the organic EL element by a driving device 9 composed of a microcomputer or the like. The user 90 observes data such as characters and images by emitting L.
[0022]
FIG. 2 is an enlarged plan view showing a part of the display panel, and FIG. 3 is a sectional view taken along line III-III in FIG. The display panel 10a of the present example has a large number of pixels arranged in a matrix form from an organic electroluminescence element, and can be driven by an active matrix method or a passive matrix method. In the display panel 10a, a single light emitting layer 14 and a display body or a self light emitting element 19 having a reflective surface 13a provided around the light emitting layer 14 constitute one pixel, and a plurality of display bodies 19 are formed. They are arranged in an array or matrix in the two-dimensional direction. Therefore, a two-dimensional image can be displayed by driving each display body 19. The individual display bodies 19 are arranged between the electrodes, and the light emitting layer 14 that spontaneously emits light by applying a voltage between the electrodes, covers the emission side of the light emitting layer 14, and forms an interface 18a with the outside. The direction of the light L2 propagating through the inside of the protective layer 18 is less than the critical angle of the interface 18a of the protective layer by the reflecting surface 13a that is an angle conversion portion provided around the light emitting layer 14. In this way, the light utilization efficiency or the light extraction efficiency is enhanced.
[0023]
The display panel 10a includes a substrate 11 serving as a support for a panel such as a glass substrate, and a cathode made of a metal layer such as aluminum or a dielectric multilayer film on the upper surface or the surface 11a together with a signal line or a driving element. A layer 12 (also referred to as an electrode layer 12 or a reflective layer 12) is stacked. Therefore, in the display panel 10a of this example, the cathode layer 12 is reflective, and part of the light emitted from the light emitting layer 14 is reflected toward the protective layer 18 or the light totally reflected at the interface 18a is reflected. It has a function of reflecting to the protective layer 18 side. Further, on the upper surface 11 a of the substrate 11, a bank 13 made of polyimide and having a predetermined height is laminated in a predetermined pattern, and a region 21 surrounded on all sides by the bank 13 is formed. This area | region 21 is an area | region where the organic electroluminescent light emitting layer 14 is formed into a film, and becomes a light emission area | region. In this example, a 60 μm × 190 μm rectangular light emitting region 21 is formed. A region 22 including the light emitting region 21 and one inclined side surface (slope) of the bank 13 corresponds to one pixel in the display panel 10a, and is, for example, a pixel region of 80 μm × 240 μm.
[0024]
The light emitting layer 14 is formed in the region 21 using an ink jet technique. The bank 13 is a layer that can be used for alignment when forming the light emitting layer 14, and is a layer for separating the light emitting layer 14. The light emitting layer 14 may be a single layer made of organic EL, or a layer to which a hole transport layer or an electron transport layer is added in order to improve the light emission efficiency. A transparent electrode (anode layer) 15 made of ITO is formed on the light emitting layer 14. By applying a voltage to the cathode layer 12 and the anode layer 15, the light emitting layer 14 disposed between these electrodes is formed. Lights spontaneously. A protective layer 18 is laminated on the anode layer 15 (on the emission side), the emission side of the light emitting layer 14 is covered with the protective layer 18, and an interface 18 a with the outside world is formed by the protective layer 18. Here, the electrode layer 12 is a cathode and the electrode layer 15 is an anode. However, the electrode layer 12 is limited to the above combination as long as the electrode layer 12 is a reflective electrode and the electrode layer 15 is a light-transmissive electrode. It is not a thing.
[0025]
The protective layer 18 is a thin transparent layer, and light emitted obliquely from the light emitting layer 14 at an angle larger than the critical angle with respect to the interface 18 a is totally reflected at the interface 18 a within the area of the light emitting layer 14. It is thick enough. In other words, the conventional display panel that converts the angle on the slope uses a thick protective layer that prevents the light emitted at the angle of total reflection from the light emitting layer from reaching the interface between the protective layer and the outside world. On the other hand, in the display panel 10a of this example, on the contrary, a thin protective layer 18 is formed so that light emitted at an angle equal to or greater than the critical angle reaches the interface 18a and is reflected. For this reason, of the light L emitted from the light emitting layer 14, the light L1 less than the critical angle of the interface 18a is output from the interface 18a to the outside, and the light L2 greater than the critical angle of the interface 18a is totally reflected by the interface 18a. Then, the light returns to the light emitting layer 14 side and is reflected again by the electrode layer 12. By repeating this, the light L2 having a critical angle or more propagates inside the protective layer 18. For example, in the case of the protective layer 18 having a refractive index of 1.5, the light L2 incident on the interface 18a at an angle of about 42 degrees or more is totally reflected at the interface 18a and propagates through the protective layer 18.
[0026]
The light L2 propagating through the protective layer 18 reaches the slope of the bank 13 around the light emitting region 21, where the angle changes and becomes less than the critical angle, and is output to the outside through the interface 18a. That is, the side surface 13a of the bank 13 is inclined so as to become wider toward the emission side, and a reflective film 24 such as aluminum is formed on the side surface 13a. For this reason, the direction (angle) of the light L2 that has been repeatedly reflected between the interface 18a and the reflective layer 12 is changed by the reflective surface 13a. Accordingly, the light L2 reflected by the reflecting surface 13a is incident on the interface 18a at a angle less than the critical angle and is output to the outside. For this reason, in the display panel 10a of this example, since the thin protective layer 18 is used, there is light L2 that is totally reflected at the interface 18a. However, the light L2 reaches the reflecting surface 13a by multiple reflection, and there. Since the direction is changed and the light is output to the outside world, almost no light is confined by total reflection. Therefore, it is possible to provide a display panel having a high light utilization efficiency or extraction efficiency similar to or higher than that of a conventional display panel having a thick protective layer and a high reflection surface.
[0027]
In the case of a conventional display panel, a protective layer is formed so that light emitted from the light emitting layer toward the interface with the outside world is not totally reflected at the interface, so it is necessary to increase the thickness of the protective layer. The thickness varies depending on the area of the light emitting region or the pixel region, but is equal to or larger than the size of the pixel. For example, when the light emitting region or the pixel region is about 50 μm × 50 μm, the protective layer 18 having a thickness of about 70 μm is required. On the other hand, in the display panel 10a of the present example, since it is premised on total reflection at the interface 18a between the protective layer 18 and the outside world, the protective layer 18 can be thinned to the limit that performs the protective function. . Therefore, for example, it is possible to manufacture a display panel using a very thin protective layer 18 of several μm for a light emitting region or pixel region of 50 μm × 50 μm. Therefore, the thickness of the protective layer can be reduced to about 1/10, and a very thin display panel can be realized.
[0028]
Furthermore, the reflecting surface 13a provided around the light emitting layer 14 is for changing the direction of light that is multiply reflected between the protective layer 18 and the reflecting layer 12, and from the light emitting layer 14 by one reflection. The direction of the light is not changed so that the emitted light is not totally reflected at the interface 18a. Therefore, unlike a conventional display panel, it is not necessary to have a height at which light emitted from the light emitting layer 14 can be incident at an angle that causes total reflection. For this reason, the effect that the area per pixel can be made small is also acquired. FIG. 4 shows the relationship between the light emitting region 21 in the pixel region 22 and the region occupied by the reflecting surface 13a. If the angle of the reflective surface of the display panel 10a is equal to the angle of the reflective surface of the conventional display panel, the height can be lowered, and therefore the region 25 necessary for forming the reflective surface 13a can be narrowed. Therefore, the light emitting region 21 having the same light amount as that of the conventional case can be formed in the small pixel region 22, and the luminance per pixel is increased. Furthermore, since the light that has propagated through the protective layer 18 is output from the periphery of the pixel, the display body 19 has the same or a large amount of ambient light with respect to the center, and a high-contrast display with a solid outline is possible.
[0029]
In other words, in the conventional method, since the pitch between pixels is limited to some extent, the height of the reflection surface is limited, and the amount of light that is angle-converted by the reflection surface and output from the interface is also large. It is limited. On the other hand, in the present invention, the protective layer 18 can be made thin, and the height of the reflecting surface (slope) 24 can be lowered. Therefore, it is possible to make a slope that is the same as or higher than the protective layer 18. is there. Therefore, the light propagating through the protective layer 18 can be output from the interface 18a by changing its angle without missing the light. Therefore, in this respect, it is possible to provide the display panel 10a which is thin and has high light extraction efficiency. However, if the protective layer 18 is thinned, the number of multiple reflections increases. The reflection at the interface 18a is total reflection, and there is no loss, but there is absorption on the metal surface such as aluminum of the electrode 12, and there is also absorption while propagating through the protective layer 18 and the like. Therefore, by making the protective layer thin, loss due to absorption occurs, which may affect the light extraction efficiency.
[0030]
In any case, in the display panel 10a of this example, the protective layer 18 can be made thin without decreasing the light extraction efficiency or increasing the light extraction efficiency. Therefore, with this structure, the conflicting demands of improving the light extraction efficiency and reducing the thickness of the display panel can be achieved simultaneously, and a bright and thin display panel can be manufactured or provided. In addition, a low reflective surface can be adopted, and not only the light extraction efficiency is improved, but also a synergistic advantage that the luminance per pixel is easily improved, so a display panel capable of displaying a very bright image is provided. it can. Further, the display panel 10a is an optimum configuration for manufacturing a thin display panel because the electrode 12 disposed on the reflection output side of the light emitting layer 14 is also used as a reflection layer. In addition, since it is not necessary to spend more energy than necessary to increase the luminance, the power consumption of the display device 1 can be reduced, and the reliability of the organic EL can be improved.
[0031]
FIG. 5 shows a method for manufacturing the display panel 10a. A substrate 11 such as a glass substrate is prepared as shown in FIG. 5A, and an electrode layer (cathode layer) 12 made of aluminum is laminated on the surface 11a of the substrate 11 as shown in FIG. Then, a bank 13 made of polyimide is formed on the electrode layer 12, and an aluminum film or a dielectric multilayer film to be a reflective film 24 is formed on the side surface (slope) 13 a of the bank 13. When forming a conductive reflective film such as aluminum, it is necessary to form an insulating film so that the electrodes 12 and 15 do not short-circuit.
[0032]
Next, as shown in FIG. 5C, an ink droplet made of an organic EL material is dropped or landed on the region surrounded by the bank 13 by an ink jet method to form a light emitting layer 14. Then, an electrode layer (anode layer) 15 is laminated on the light emitting layer 14. Next, as shown in FIG. 5D, a thin protective layer 18 is laminated on the emission side of the substrate 11 on which the electrode layer 12, the bank 13, the light emitting layer 14, and the electrode layer 15 are formed. Thereby, the display panel 10a is manufactured.
[0033]
FIG. 6 is a sectional view showing a different display panel 10b. In the display panel 10 a, the reflective surface 13 a is formed on the bank 13 surrounding the light emitting layer 14, and the reflective surface 13 a is disposed on the side of the light emitting layer 14. That is, there is no gap between the reflecting surface 13a and the light emitting layer 14 in the vertical direction or the emission direction. For this reason, leakage (crosstalk) of light emitted from the light emitting layer 14 is prevented, and the light utilization efficiency is maximized. Further, although the protective layer 18 is slightly laminated on the bank 13, the protective layer 18 may be provided on the anode layer 15, and the thickness is the same as the bank 13, or The anode layer 15 can be covered with the protective layer 18 having a thickness lower than that of the bank 13. For this reason, the thickness of the display panel can be made very thin. However, in this display panel 10a, in order to prevent a short circuit between the electrodes, it is necessary to form an insulating layer when forming the reflective surface 13a, and there is a possibility that the manufacture of the display panel becomes slightly complicated.
[0034]
On the other hand, the display panel 10b shown in FIG. 6 does not form the reflective film 24 on the slope 13a of the bank 13, but forms the anode layer 15 on the bank 13 and the light emitting layer 14, and further the anode layer 15 A protrusion 25 made of an insulating material is formed at a position overlapping the bank 13 on the top. A reflective film 24 is formed on the slope 25 a of the protrusion 25, and a region surrounded by the protrusion 25 is covered with the protective layer 18. In the display panel 10b, there is no fear that the electrodes are short-circuited by the reflective film 24, and it is not necessary to form an insulating film for preventing a short-circuit between the electrodes. For this reason, the display panel 10b can be manufactured easily. However, since a gap is generated in the emission direction between the light emitting layer 14 and the reflecting surface 25a, light leakage may occur in the bank 13 portion. The height of the projection 25 in the display panel 10b can be various heights such as the same level as that of the bank 13, but it is desirable to make the projection 25 low in order to make the display panel thin. On the other hand, when a certain amount of thickness is required to exhibit a sufficient function as the protective layer 18, there is an advantage that the thickness of the protective layer 18 can be freely controlled by adjusting the height of the protrusion 25.
[0035]
The display panel 10b can be manufactured as follows. First, as in the display panel 10a, as shown in FIG. 7B, the electrode layer 12, the bank 13 and the light emitting layer 14 are formed on the surface 11a of the substrate 11 shown in FIG. 7A. Then, as shown in FIG. 7C, the electrode layer 15 is formed on the light emitting layer 14 and the bank 13, and the protrusion 25 made of an insulating material is formed on the bank 13, that is, on the bank 13. Then, the reflective film 24 is formed on the slope 25 a of the protrusion 25. Next, as shown in FIG. 7D, a material for forming a protective layer is injected into a region surrounded by the protrusions 25 to form the protective layer 18. Thereby, the display panel 10b is manufactured.
[0036]
FIG. 8 shows a further different display panel 10c in a sectional view. In this display panel 10c, a transparent layer 30 having a refractive index different from that of the protective layer 18 is formed on the bank 13, and a refracting surface 31 is formed as an angle conversion portion so that the emission direction becomes narrow. Thus, the angle conversion unit can be realized by a refracting surface in addition to the reflecting surface.
[0037]
FIG. 9 shows a further different display panel 10d in a sectional view. In this display panel 10 d, a concave portion 28 is formed in the protective sheet 18, a reflective film 24 is formed on the wall surface 28 a of the concave portion 28, and the substrate 11 on which the bank 13 and the like are formed with the protective sheet 18 interposed through the adhesive layer 26. It is the structure joined to the injection | emission side. In the case of this configuration, if the distance between the apex of the mirror 24 and the interface 18a of the protective sheet 18 is long, light leakage occurs between them. For this reason, it is desirable to prevent light leakage by shortening these distances as much as possible.
[0038]
In any of the above examples, the reflecting surface is inclined so as to expand toward the exit side, but may be inclined so as to narrow toward the exit side. However, if the reflecting surface is widened toward the exit side, the number of multiple reflections between the interface 18a and the reflecting layer 12 can be reduced, so that the absorption loss in the reflecting layer 12 and the transmittance of the light emitting layer 14 and the like can be reduced. Considering this, it is desirable that the reflecting surface is widened toward the exit side from the viewpoint of suppressing a decrease in light intensity due to multiple reflection.
[0039]
Further, the display panel of the present invention has been described by way of example of a display panel mounted on a mobile phone, but the present invention can also be applied to a small display panel mounted on a PDA, a car navigation system, etc. The present invention can also be applied to a large-sized display panel such as a 30-inch display, a PC display, a TV, and the like, which have been actively developed in recent years. Moreover, although the light emitting layer using an organic EL element was demonstrated, the display using the light emitting layer which light-emits spontaneously by applying a voltage between electrodes, such as PDP, a light emitting diode, inorganic EL, organic EL, and field emission. The present invention can be applied to any panel.
[0040]
【The invention's effect】
As described above, in the present invention, the total reflection at the interface is positively utilized and the angle of the totally reflected light is converted by an angle conversion unit such as a reflection surface provided around the light emitting layer. Yes. As a result, a thin protective layer is employed to improve the light extraction efficiency in the same manner as a display panel having a conventional reflective slope, so that a bright and very thin self-luminous element and display panel can be manufactured. Further, according to the present invention, it is possible to change the light propagation angle on a low reflecting surface, and not only the light extraction efficiency can be improved, but also the luminance per pixel can be improved by reducing one pixel. . Accordingly, the self-luminous element and the display panel are capable of displaying images or characters that are much brighter than conventional ones although they are thin.
[Brief description of the drawings]
FIG. 1 is a diagram showing a display device (mobile phone) equipped with a display panel according to the present invention.
FIG. 2 is a plan view schematically showing a display panel according to the present invention.
3 is a cross-sectional view schematically showing the display panel shown in FIG.
4 is a diagram for explaining a relationship between a light emitting region and a pixel region of the display panel shown in FIG.
5 is a diagram showing a method of manufacturing the display panel shown in FIG. 2. FIG.
FIG. 6 is a cross-sectional view schematically showing different display panels.
7 is a diagram showing a method of manufacturing the display panel shown in FIG. 6. FIG.
FIG. 8 is a diagram schematically showing another display panel.
FIG. 9 is a diagram schematically showing another display panel.
[Explanation of symbols]
1 Mobile phone
10a, 10b, 10c, 10d Display panel
11 Base substrate
12 electrodes (reflective layer)
13 banks
14 Light emitting layer
14a Reflective surface
18 Protective layer
18a interface
24 Reflective film
25 Protrusions

Claims (8)

A light emitting layer disposed between the electrodes and emitting light by a voltage applied between the electrodes;
A protective layer that covers the emission side of the light emitting layer and forms an interface with the outside world, such that light emitted from the light emitting layer is totally reflected at least once at the interface within the area of the light emitting layer. A protective layer of thickness;
A reflective layer covering the opposite side of the protective layer with respect to the light emitting layer;
Around the light emitting layer, an angle conversion unit that changes the direction of the light emitted from the light emitting layer and propagates in the protective layer to be less than the critical angle with respect to the interface;
A bank protruding to the emission side to separate the light emitting layer from other light emitting layers;
A protrusion made of an insulating material protruding from the bank to the emission side;
A self-luminous element in which an inner surface of the projection serves as the angle conversion portion, and the protective layer is formed in a region surrounded by the projection.   The self-luminous element according to claim 1, wherein the reflective layer is one of the electrodes.   The self-luminous element according to claim 1, wherein the angle conversion unit is a reflecting surface that is inclined so that the emission side is widened.   The self-luminous element according to claim 1, wherein the angle conversion unit is a refracting surface that is inclined so that the emission side becomes narrow.   The self-luminous element according to claim 1, wherein the light-emitting layer is an organic electroluminescence light-emitting layer. A plurality of light emitting layers disposed between the electrodes and emitting light by a voltage applied between the electrodes;
A protective layer that covers the emission side of these light emitting layers and forms an interface with the outside world, and the light emitted from the plurality of light emitting layers is at least once at the interface within the area of the corresponding light emitting layer. A protective layer with a reflective thickness;
A reflective layer covering the opposite side of the protective layer with respect to the light emitting layer;
Around the light emitting layer, an angle conversion unit that changes the direction of the light emitted from the light emitting layer and propagates in the protective layer to be less than the critical angle with respect to the interface;
A bank protruding to the emission side to separate the plurality of light emitting layers;
Having a protrusion from an insulating material protruding from the bank to the injection side,
A display panel in which an inner surface of the protrusion serves as the angle conversion portion, and the protective layer is formed in a region surrounded by the protrusion.   A display device comprising: the display panel according to claim 6; and a driving device that drives the light emitting layer of the display panel to display an image. A light-emitting layer disposed between the electrodes and emitting light by a voltage applied between the electrodes; and a protective layer that covers an emission side of the light-emitting layer and forms an interface with the outside world, the light emitted from the light-emitting layer A protective layer having a thickness enough to totally reflect at least once at the interface within the area of the light emitting layer, a reflective layer covering the opposite side of the protective layer with respect to the light emitting layer, and around the light emitting layer The light emitting device has a self-luminous element manufacturing method comprising: an angle conversion unit that changes the direction of light emitted from the light emitting layer and propagates in the protective layer so as to be less than a critical angle with respect to the interface. And
Forming a protrusion protruding from the bank protruding to the emission side with an insulating material to separate the light emitting layer from the other light emitting layer, and forming the inner surface of the protrusion as the angle conversion portion;
And a step of forming the protective layer in a region surrounded by the protrusion.

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