JP5771991B2 - EL element and illumination device, display device, and liquid crystal display device including the same - Google Patents

Description

  The present invention relates to an EL element (electroluminescence element), a lighting device including the EL element, a display device, and a liquid crystal display device.

  In general, an organic EL element is configured by providing a light emitting structure in which a light emitting layer containing a fluorescent organic compound is sandwiched between an anode and a cathode on one surface of a translucent substrate. This organic EL element generates excitons by applying a DC voltage between the anode and the cathode, injecting electrons and holes into the light emitting layer and recombining them, and the excitons are deactivated. It emits light using the emission of light.

  In such an EL element, when light emitted from the light emitting layer is emitted from the translucent substrate to the outside, a part of the light is totally reflected on the surface of the translucent substrate and is emitted to the outside. There was a problem that a loss of light amount occurred. The light extraction efficiency at this time is generally said to be about 20%. For this reason, as the high luminance is required, more input power is required, and the load on the EL element is increased to reduce the reliability of the element itself.

On the other hand, in order to improve the external extraction efficiency of light in the EL element, a fine unevenness is formed on the translucent substrate, and a part of the lost light beam is extracted to the outside by total reflection. Devices have been proposed. For example, Patent Document 1 proposes forming a microlens array formed by planarly arranging a plurality of microlens elements on one surface of a translucent substrate.
Alternatively, as described in Patent Document 2, a method of improving the light extraction efficiency by adjusting the light distribution from the light emitting layer in the EL element has been studied.

JP 2002-260845 A JP 2004-296423 A

However, the above-described conventional technology is not sufficient for improving the light extraction efficiency of the EL element.
This invention is made | formed in view of such a situation, It aims at providing the EL element which can improve light extraction efficiency, the illuminating device using this EL element, a display apparatus, and a liquid crystal display device. To do.

但し、θ１：第１光再分配面、第２光再分配面の傾斜角度、
θｉｎ１：発光層から射出された光の射出角度、
ｎ：光再分配シートの屈折率。 In order to achieve the above object, the present invention provides the following means.
An EL device according to the present invention is an EL device including a light-transmitting substrate and a light-emitting layer provided on one surface of the light-transmitting substrate and sandwiched between an anode and a cathode. A light redistribution sheet that is provided on the other surface facing one surface and emits incident light, and a light reflection layer that is provided on the opposite side of the light redistribution sheet with respect to the light emitting layer, The light redistribution sheet has a light redistribution structure, and the light redistribution structure extends in the first direction and has an apex angle formed by intersecting with each other within a range of 86 degrees to 94 degrees. A pair of first light redistribution surfaces formed so as to be inclined and extend in a second direction that intersects the first direction at an angle of 80 degrees or more and within 90 degrees and intersects each other. A pair of second light redistribution surfaces formed so as to be inclined so that the angle of the top portion is not less than 86 degrees and not more than 94 degrees. And the light emitting layer has a ratio of the amount of the first emitted light having an emission angle θin1 satisfying the following expression (1) and the total amount of light emitted from the light emitting layer: (2) It is larger than Formula.

Where θ1: the inclination angle of the first light redistribution surface and the second light redistribution surface,
θin1: an emission angle of light emitted from the light emitting layer,
n: Refractive index of the light redistribution sheet.

According to the EL device of the present invention, the light redistribution structure portion is formed in a pair of first lights formed so as to be inclined so that apex angles extending in the first direction and intersecting each other are 86 degrees to 94 degrees. A first light redistribution member having a redistribution surface and a second direction that intersects the first direction at an angle of 80 degrees to 90 degrees and an apex angle that intersects each other is 86 degrees to 94 degrees And a second light redistribution member having a pair of second light redistribution surfaces formed so as to be inclined so that the light emitted from the light emitting layer has a predetermined light distribution. The first light redistribution surface and the second light redistribution surface that intersect each other in the range of 80 degrees to 90 degrees of the light redistribution structure portion of the light redistribution sheet can be transmitted. The light with directivity can be increased by refracting the light, and the light redistribution structure A part of the light reflected by the first and second light redistribution surfaces is reflected by the light reflection layer via the light emitting layer and is directed again to the light redistribution sheet, so that a part of the light is further reflected by the light. Light can be redistributed via the redistribution structure portion to be taken out with directivity, and external light extraction efficiency can be improved.
The light reflecting layer may be used also as the cathode or may be provided separately from the cathode.

但し、θｉｎ２：発光層から射出された光の射出角度。 An EL element according to the present invention is an EL element including a light-transmitting substrate and a light-emitting layer provided on one surface of the light-transmitting substrate and sandwiched between an anode and a cathode. A light redistribution sheet that is provided on the other surface opposite to one surface of the substrate and emits incident light; and a light reflection layer that is provided on the opposite side of the light redistribution sheet with the light emitting layer interposed therebetween. The light redistribution sheet has a light redistribution structure, and the light redistribution structure extends in a first direction along the other surface of the translucent substrate and is formed to intersect with each other. In a second direction that intersects with the pair of first light redistribution surfaces formed at an angle of 86 to 94 degrees and an angle of 80 to 90 degrees with respect to the first direction. A pair of second portions that are formed so as to be inclined so that an angle of a top portion that extends and intersects each other is 86 degrees to 94 degrees. The light emitting layer is formed with a redistribution surface, and the light emitting layer has a light quantity of second emitted light having an emission angle θin2 satisfying the following expression (3) equal to or greater than 42.5% of the total light quantity emitted from the light emitting layer. It is characterized by that.

Where θin2 is an emission angle of light emitted from the light emitting layer.

  According to the EL device of the present invention, the amount of the second emitted light having the emission angle θin2 satisfying the expression (3) is 42.5% or more of the total amount of light emitted from the light emitting layer, and thus the light emission from the light emitting layer. The directivity of the light can be improved because the light to be transmitted has a predetermined light distribution, and the first light redistribution intersecting each other in the range of 80 to 90 degrees of the light redistribution structure portion of the light redistribution sheet The light having directivity can be increased by transmitting and refracting each of the surface and the second light redistribution surface, and in addition, the first and second light redistribution surfaces of the light redistribution structure portion A part of the reflected light is reflected by the light reflection layer via the light emitting layer and is directed again to the light redistribution sheet, so that a part of the light further passes through the light redistribution structure. It can be redistributed and taken out to the outside with directivity, improving external light extraction efficiency It is allowed to be able to increase the light utilization efficiency than Lambert distribution.

The pair of first light redistribution surfaces is a first light redistribution member having a prism shape having a substantially triangular cross section, and the pair of second light redistribution surfaces is a second light redistribution having a prism shape having a substantially triangular cross section. It may be a member.
The light redistribution structure part formed by arranging the first light redistribution member and the second light redistribution member intersecting in the range of 80 degrees to 90 degrees, the emitted light having a predetermined light distribution from the light emitting layer, or By transmitting the reflected light recycled by the light reflecting layer, directivity can be given in a predetermined direction.

Further, the light redistribution sheet or the bonding layer of the light redistribution sheet preferably has a light diffusion function.
In this case, even if the emission angle θin2 from the light emitting layer exceeds 50 ° or is less than 25 °, the light diffusion function allows the light to be regenerated at an incident angle within the range of the above equation (3). Since it can adjust so that it can inject into a distribution sheet, the light utilization efficiency can be improved also from this point.
In this case, you may have a light-diffusion function by mixing a light-diffusion agent with the light redistribution structure.
Or you may make it have a light-diffusion function by mixing a light-diffusion agent with the joining layer which joins a light redistribution sheet | seat to a translucent board | substrate.

In addition, the lighting device according to the present invention includes any one of the above-described EL elements as light emitting means.
ADVANTAGE OF THE INVENTION According to this invention, the external light extraction efficiency of the light light-emitted from the light emitting layer of EL element by an illuminating device can be improved, and the illumination efficiency of an illuminating device can be improved.

A display device according to the present invention includes any one of the above-described EL elements, and is configured such that the EL elements are pixel-driven.
Also according to the present invention, it is possible to improve the external light extraction efficiency of light emitted from the light emitting layer of the EL element by the lighting device, and the lighting efficiency of the lighting device can be improved.

A liquid crystal display device according to the present invention is a liquid crystal display device including an image display element, and is configured by disposing any of the above-described EL elements or the above-described illumination device on the back surface of the image display element. It is characterized by being.
Thereby, the illumination efficiency of the liquid crystal display device can be improved by the light transmitted from the EL element being transmitted through the image display element or the light emitted from the illumination device incorporating the EL element.

  According to the EL device of the present invention, the light redistribution structure portion is formed to be inclined so that the apex angle formed by extending in the first direction and intersecting each other is 86 degrees or more and 94 degrees or less. A pair of first light redistribution surfaces extend in a second direction that intersects the first direction at an angle of 80 degrees or more and 90 degrees or less, and an apex angle formed by intersecting each other is 86 degrees or more and 94. And a pair of second light redistribution surfaces formed so as to be within a certain degree, so that the light emitted from the light emitting layer has a predetermined light distribution, so that the reflected light can be repeatedly regenerated. The light can be emitted to the distribution structure and redistributed by the first and second light redistribution surfaces to improve the light directivity, and the external light extraction efficiency of the light redistribution sheet can be improved. .

  In addition, the illumination device, the display device, and the liquid crystal display device according to the present invention can improve the light utilization efficiency by including the above-described EL element.

It is principal part sectional drawing which shows the path | route of the EL element which concerns on one Embodiment of this invention, and an emitted light. It is principal part sectional drawing which shows the conventional EL element which is not provided with the light redistribution structure layer. 1A and 1B show a light redistribution sheet of an EL element in an embodiment, in which FIG. 3A is a perspective view, FIG. 3B is a side view seen from the Y-axis direction, and FIG. 3C is a side view seen from the X-axis direction. . In the EL element in the embodiment, it is a diagram showing a simulation result of a light distribution characteristic showing a change in relative light quantity with respect to an emission angle according to the number of cycles of reflected light for the emitted light by repetition from the light redistribution sheet. As for the second light redistribution member, (a) is a diagram when the apex angle is set to 96 °, and (b) is a diagram when the apex angle is set to 94 °. FIG. 5 is a diagram showing a simulation result of a light distribution characteristic showing a change in relative light quantity with respect to light emitted from the light redistribution sheet, as in FIG. 4, and (a) shows the first and second light redistribution members. When the angle is set to 86 °, (b) is a diagram illustrating a simulation result of the light distribution characteristics when the apex angle is set to 84 °. It is a figure which shows the light distribution of the relative integrated light quantity with respect to the emission angle of the light inject | emitted from a light emitting layer. It is a figure which shows the simulation result of the light utilization efficiency of the emitted light with respect to the incident angle to a light redistribution sheet. It is a figure which shows the 1st modification of a light redistribution sheet | seat, (a) is a principal part perspective view, (b) is the side view seen in the Y-axis direction, (c) is the side view seen in the X-axis direction. is there. It is a figure which shows the 2nd modification of a light redistribution sheet | seat, (a) is a fragmentary perspective view, (b) is the side view seen in the Y-axis direction, (c) is the side view seen in the X-axis direction. . It is a figure which shows the 3rd modification of a light redistribution sheet | seat, (a) is a fragmentary perspective view, (b) is the side view seen in the Y-axis direction, (c) is the side view seen in the X-axis direction. . It is a figure regarding another modification of a light redistribution sheet, (a), (b), (c) is a figure showing various bottom shape of a light redistribution member of a light distribution structure layer of a light redistribution sheet. . It is a figure which shows another modification of a light redistribution sheet, and is a figure which shows the bottom face shape of the light redistribution member of a light redistribution sheet.

Hereinafter, an EL element according to an embodiment of the present invention, and an illumination device, a display device, and a liquid crystal display device including the EL device according to an embodiment of the present invention will be described with reference to FIGS.
First, the EL element according to the present embodiment is provided, for example, in a lighting device as a light emitting means, or in a display device so that the EL element is driven by a pixel, or disposed on the back surface of an image display element. Used in the apparatus. Further, in the liquid crystal display device, an illuminating device including the EL element according to the present embodiment as a light emitting means may be arranged on the back surface of the image display element.

As shown in FIG. 1, the EL element 1 according to the present embodiment includes a light emitting layer 4 having an anode 5 and a cathode 6 between a first substrate 2 and a second substrate 3 made of a translucent substrate. They are arranged in a stacked state sandwiched between them. The light emitting layer 4 is sandwiched between the anode 5 and the cathode 6 to form a light emitting structure 8, the anode 5 is disposed on the light emitting side from the light emitting layer 4, and the cathode 6 is disposed on the back side of the light emitting layer 4. Has been. Further, a light redistribution sheet 7 for emitting light emitted from the light emitting layer 4 to the outside is provided on the surface of the first substrate 2 opposite to the light emitting structure 8.
The light emitting structure 8 is formed by sandwiching between the first substrate 2 and the second substrate 3 and integrally stacking them. Further, the light redistribution sheet 7 is integrally laminated on the upper surface side of the first substrate 2 via the bonding layer 10.

  For the first substrate 2 and the second substrate 3, various glass materials can be used as materials, plastic materials such as PMMA, polycarbonate, polystyrene, or metal materials such as aluminum can be used. . Furthermore, although various other materials can be used, a particularly preferable material is a cycloolefin-based polymer, and this polymer has all of material properties such as processability and heat resistance, water resistance, and optical translucency. It is excellent. In addition, the first substrate 2 is formed using a material (for example, glass) capable of making the total light transmittance 50% or more so that the light emitted from the light emitting structure 8 can be transmitted as much as possible. It is preferable to do.

  Here, the light emitting structure 8 is one in which the light emitting layer 4 emits light by applying a voltage between the anode 5 and the cathode 6, and various conventionally known configurations can be employed. When the light-emitting layer 4 is a white light-emitting layer, the structure composed of the anode 5 / light-emitting layer 4 / cathode 6 is, for example, ITO / CuPc (copper phthalocyanine) / α-NPD doped with rubrene 1% / dinactylanthracene perylene. 1% dope / Alq3 / lithium fluoride / cathode 6 is made of Al.

  Moreover, it is also possible to employ | adopt the arbitrary structures using the appropriate material which can make the wavelength of the light ray inject | emitted from the light emitting layer 4 into R (red), G (green), and B (blue). That is, the light emitting layer 4 of blue, red, yellow, green, etc. can be formed. For this reason, when the EL element 1 is used for a full-color display application, the three types of light-emitting materials corresponding to R, G, and B are separately applied, or a color filter is superimposed on white light to display a full color. do it.

Furthermore, in the present embodiment, the cathode 6 is formed of a material having a light reflection function and has a function as a light reflection layer. In this specification, the cathode 6 may be referred to as a light reflecting layer 9. In the present embodiment, since the cathode 6 has the function of the light reflection layer 9, the light reflection layer 9 is provided on the side opposite to the light redistribution sheet 7 with the light emitting layer 4 in between. The light reflection layer 9 that is the cathode 6 preferably has a light reflectance of 50% or more and 100% or less.
In the EL element 1 shown in FIG. 1, the cathode 6 is made of a material having light reflectivity and also serves as the light reflection layer 9, but the anode 5 also serves as the light reflection layer instead. Alternatively, a light reflecting layer 9 may be separately provided below the cathode 6, that is, on the side opposite to the light emitting layer 4. Further, in order to transmit light to the anode 5 and the cathode 6, the anode 5 and the cathode 6 may be transparent electrodes.

Examples of the pressure-sensitive adhesive and adhesive constituting the bonding layer 10 for bonding the light redistribution sheet 7 and the first substrate 2 include various pressure-sensitive adhesives and adhesives such as acrylic, urethane, rubber, and silicone. Can be mentioned. In any case, since it is used adjacent to the light emitting structure 8 that is at a high temperature, it is desirable that the storage elastic modulus G ′ is about 1.0E + 04 (Pa) or more at 100 ° C. If the storage elastic modulus is lower than this, a positional deviation may occur between the light redistribution sheet 7 and the first substrate 2 during use. If a large misalignment occurs between the light redistribution sheet 7 and the first substrate 2, light from the light emitting structure 8 cannot efficiently enter the light redistribution sheet 7, resulting in a disadvantage that the light use efficiency is reduced. .
In order to stably secure a gap between the light emitting layer 4 and the light redistribution sheet 7, transparent fine particles such as beads may be mixed in the bonding layer 10. Further, the pressure-sensitive adhesive or adhesive constituting the bonding layer 10 may be a double-sided tape or a single layer.

  The light redistribution sheet 7 provided on the first substrate 2 via the bonding layer 10 includes a base material 11 and unevenness formed on the base material 11 to form the light emitting side surface of the EL element 1. And an optical redistribution structure layer (uneven portion) 12. Here, the light redistribution sheet 7 may be formed by forming the light redistribution structure layer 12 separately from the base material 11, or the light redistribution structure layer 12 and the base material 11 may be integrally formed.

In the EL element 1, the light B 0 emitted from the light emitting layer 4 by applying a voltage between the anode 5 and the cathode 6 passes through the first substrate 2 and enters the light redistribution sheet 7. In the light redistribution sheet 7, a part of the light B0 is transmitted to the outside as the light B2, and the rest is reflected to the inside as the light B1. The reflected light B1 becomes light B3 directed to the light reflecting layer 9 (cathode 6), is reflected by the light reflecting layer 9, and becomes light B4 directed again toward the light redistribution sheet 7.
The light B4 passes through the first substrate 2 and enters the light redistribution sheet 7. However, depending on the incident angle to the light redistribution sheet 7, the light B4 becomes transmitted light B2 or light B1 that is reflected again. Then, the cycle of the light B1, the light B3, and the light B4 is repeated until the reflected light B1 finally becomes the transmitted light B2. Thereby, the traveling direction (irradiation direction F) of the light B2 that has passed through the light redistribution sheet 7 can be aligned, and the directivity of the EL element 1 can be enhanced.

  On the other hand, as shown in FIG. 2, when the light redistribution sheet 7 does not have the light redistribution structure layer 12 and the surface is the flat surface 12A, most of the light B1 is not transmitted but reflected by the flat surface 12A. Then, the light B12 is incident on the light emitting layer 4 again. However, since the light B12 is not deflected in the irradiation direction F, a loss occurs. In addition, the light B2 emitted from the EL element 1 becomes light depending on the light distribution from the light emitting layer 4, and cannot be directional light. That is, in order to improve the light directivity and the external extraction efficiency of the EL element 1, it is important to appropriately set (optimize) the surface shape of the light redistribution sheet 7A.

Next, the light redistribution structure layer 12 of the light redistribution sheet 7 that improves the light directivity and the external extraction efficiency of the EL element 1 in this embodiment will be described with reference to FIG.
As shown in FIGS. 3 and 1, for example, the light redistribution structure layer 12 laminated on one surface facing the light irradiation direction F side of the sheet-like translucent base material 11 (light reflection layer), Within the light emitting side surface of the light redistribution sheet 7, for example, a plurality of first light redistribution members 14 and second light redistribution members 15 each having a substantially triangular cross section are arranged in a direction crossing each other (see FIG. 3 (a)).
The first light redistribution member 14 includes a pair of first light redistribution surfaces 16 inclined at an inclination angle θ1 with respect to the base material 11 (the upper surface thereof) in a first direction (for example, the X direction) that is an arbitrary direction. 16 is formed to extend in a substantially isosceles triangular cross section. The second light redistribution member 15 is a pair of second light redistribution members that are inclined at an inclination angle θ2 with respect to the base material 11 (the upper surface thereof) in a second direction Y that intersects the first direction X at an angle φ. The distribution surfaces 17 and 17 are formed so as to extend in a substantially isosceles triangular cross section.
A plurality of these first light redistribution members 14 and second light redistribution members 15 are arranged substantially in parallel.

The pair of first light redistribution surfaces 16, 16 constituting the first light redistribution member 14 extend along the first direction X, respectively, and the apex angle of the apex portion 14 a formed so as to intersect with each other is θ3. (See FIG. 3C). A pair of second light redistribution surfaces 17, 17 constituting the second light redistribution member 15 is a second direction that intersects the first direction X at an angle φ within the same plane as the first light redistribution member 14. The apex angle of the apex portions 15a extending along Y and intersecting with each other is set to θ4 (see FIG. 3B).
In the present embodiment, the intersection angle φ between the first direction X and the second direction Y is set to be in the range of 80 degrees or more and 90 degrees or less. Further, the apex angle θ3 of the apex portion 14a at which the pair of first light redistribution surfaces 16 intersect and the apex angle θ4 of the apex portion 17a at which the pair of second light redistribution surfaces 17 intersect each range from 86 degrees to 94 degrees. Is set to

More specifically, as shown in FIG. 3, the light redistribution structure layer 12 has, for example, a top portion 14 a continuously extending in the first direction X on the upper surface of the sheet-like translucent substrate 11. The first light redistribution member 14 is formed by providing a plurality of band-shaped prisms (or lenses) having a substantially triangular cross section without gaps, and further fitted into a recess formed on the first light redistribution member 14. As described above, the top portion 15a is provided with a plurality of strip-like prisms (or lenses) having a substantially triangular cross section extending continuously or intermittently in a second direction Y that forms an angle φ with the first direction X. A light redistribution member 15 is formed.
For example, the height of the plurality of second light redistribution members 15 has a configuration that randomly varies with respect to the first light redistribution member 14 in the example illustrated in FIG. 3.

If the apex angle θ3 of the first light redistribution member 14 and the apex angle θ4 of the second light redistribution member 15 are in the range of 86 degrees to 94 degrees, each of the pair of first light redistribution surfaces 16 is provided. Each of the pair of second light redistribution surfaces 17 need not have the same size and the same shape.
However, in order to enhance the directivity of the emitted light B2 by enhancing the light redistribution effect in the light redistribution structure layer 12, the tops of the plurality of first light redistribution surfaces 16 and second light redistribution surfaces 17 are increased. The angle θ3 and the apex angle θ4 are preferably set to the same value.
In addition, by controlling the uneven shape of the first light redistribution member 14 and the second light redistribution member 15, the light distribution of the light emitted in the irradiation direction F can be adjusted in a two-dimensional direction. For this reason, for example, by making the shape of the second light redistribution surface 17 of the second light redistribution member 15 arbitrary, the light emitted from the second light redistribution surface 17 can be symmetric or asymmetric. It is also possible to make a light distribution distribution.

  Here, the crossing angle φ between the first direction X of the first light redistribution member 14 and the second direction Y of the second light redistribution member 15 is set to 80 degrees or more and 90 degrees or less. This is because the design is such that the loss of light having a wide light distribution emitted from the light source is suppressed, more light is deflected in the irradiation direction F, and the directivity is increased. For example, in the case where only the first light redistribution surface 16 extends in the first direction X when the angle φ formed by the first direction X and the second direction Y is 0 degree, the first direction X Unevenness is not formed by the second light redistribution member 15 in the parallel direction, which is equivalent to the case where the exit surface of the light redistribution sheet 7 as shown in FIG. 2 is a flat surface 12A.

  For this reason, in FIG. 2, most of the light B1 transmitted through the first substrate 2 is reflected by the flat surface 12A without passing through the light redistribution sheet 7A, and becomes light B12 again toward the light emitting layer 4. . Since the light B12 is reflected by the flat surface 12A and is not deflected in the irradiation direction F, a lot of the light B12 is lost. Further, the light B2 transmitted through the light redistribution sheet 7A is also light derived from the light distribution from the light emitting layer 4, and does not become light having directivity deflected in the irradiation direction F. Therefore, if the second direction Y with respect to the first direction X is less than 80 degrees, the loss of light that is not extracted to the outside as in the light B12 shown in FIG. 2 increases and the light extraction efficiency decreases. End up. Also, the emitted light B2 has a drawback that the directivity in the irradiation direction F is not sufficient.

Next, the results of confirming by simulation the effects of the shape of the light redistribution structure layer 12 of the light redistribution sheet 7 and the orientation distribution characteristics from the light emitting layer 4 on the light emission characteristics of the EL element 1 are shown in FIGS. Show.
As shown in FIG. 1, the light redistribution sheet 7 in the present embodiment reflects light B1, light B3, and light reflection layer on the light redistribution sheet 7 until the light B0 from the light emitting layer 4 becomes the transmitted light B2. By repeating the cycle of the re-reflected light B4 at 9 (cathode 6), the light can be redistributed to align the traveling direction (irradiation direction F).
The light distribution characteristic of the light from the light emitting layer 4 is also redistributed and changed by repeating the above cycle. 4 to 5, the change in the light distribution characteristics of the light emitted from the light redistribution sheet 7 by changing the apex angle θ3 and the angle θ4 of the first and second light redistribution members 14 and 15. The simulation result is shown.

  4A, apex angles θ3 and θ4 = 96 degrees, in FIG. 4B apex angles θ3 and θ4 = 94 degrees, in FIG. 5A, apex angles θ3 and θ4 = 86 degrees, and in FIG. The light is redistributed by the light redistribution structure layer 12 of the light redistribution sheet 7 by repeating the cycle with θ3 and θ4 = 84 degrees. Therefore, the light quantity at a specific emission angle is relatively increased by repeating light recycling for the light distribution characteristic of the light emitted from the light redistribution sheet 7 with respect to the light distribution characteristic of the light emitted from the light emitting layer 4. It shows that

In addition, FIGS. 4 and 5 show that the value of the emission angle at which the amount of emitted light increases differs depending on the values of the apex angles θ3 and θ4 of the light redistribution sheet 7.
In FIG. 4A, when the apex angles θ3 and θ4 of the light redistribution structure layer 12 of the light redistribution sheet 7 are 96 degrees, the light distribution characteristics of the light are redistributed by repeating the cycle. This shows that the amount of light at an emission angle of 25 degrees is relatively increased by repeated reflection.
In FIG. 4B, when the apex angles θ3 and θ4 are 94 degrees, the light is redistributed by the light redistribution structure layer 12 by repeating the cycle, and the amount of light emitted at an emission angle of 20 degrees is relatively increased. It shows that it will go.
In FIG. 5A, when the apex angles θ3 and θ4 are 86 degrees, the light is redistributed by the light redistribution structure by repeating the cycle, and the amount of light emitted at an emission angle of 15 degrees is relatively increased. Is shown.
In FIG. 5B, when the apex angles θ3 and θ4 are 84 degrees, the light is redistributed by the light redistribution structure by repeating the cycle, and the light quantity at the emission angle of 10 degrees is relatively increased. Show.

The above-mentioned light redistribution occurs due to light reflection due to a difference in refractive index between the light redistribution structure layer 12 of the light redistribution sheet 7 and the atmosphere. Therefore, the value of the emission angle at which the amount of light relatively increases due to the light redistribution does not depend on the refractive index of the light redistribution structure layer 12, and the shape of the light redistribution structure layer 12, particularly the first and second light redistributions. It can be recognized that the distribution members 14 and 15 depend on the inclination angles θ1 and θ2.
On the other hand, taking out the light from the light emitting layer 4 in the front direction and emitting it depends not only on the shape of the light redistribution structure layer 12 but also on the refractive index of the light redistribution structure layer 12.
The reason for depending on the refractive index is that, when light is emitted from the light redistribution structure layer 12 to the outside of the EL element 1, light is not reflected but light is refracted and emitted to the outside. This is because the angle at which light is deflected differs depending on the refractive index difference between the layer 12 and the atmosphere.

但し、θ１：第１光再分配面１６、第２光再分配面１７の傾斜角度、
θｉｎ１：発光層４から射出された光の射出角度、
ｎ：光再分配シート７の屈折率。
この場合、傾斜角θ１＝θ２であり、異なる場合には、射出光が第１光再分配面１６と第２光再分配面１７のいずれかを透過するかによって（１）式で角度θ１またはθ２を用いる。 Here, the angle of light incident on the light redistribution structure layer 12 necessary for emitting light in the front direction of the EL element 1, that is, the light emission angle θin1 from the light emitting layer 4 can be expressed by the following equation. I can do it.

Where θ1: the inclination angle of the first light redistribution surface 16 and the second light redistribution surface 17;
θin1: an emission angle of light emitted from the light emitting layer 4,
n: Refractive index of the light redistribution sheet 7
In this case, the inclination angle θ1 = θ2, and if different, the angle θ1 or the angle θ1 in the equation (1) depends on whether the emitted light is transmitted through the first light redistribution surface 16 or the second light redistribution surface 17. θ2 is used.

The refractive index n of the light redistribution structure layer 12 is preferably 1.46 to 1.60. If the refractive index n is less than 1.46, a sufficient difference in refractive index from the atmosphere cannot be obtained, and the directivity of light decreases, which is not preferable. If the refractive index n exceeds 1.60, the difference in refractive index from the atmosphere becomes excessive, and light is reflected at the interface between the light redistribution structure layer 12 and the atmosphere and cannot be extracted from the EL element 1, which is not preferable.
When the apex angle θ3 of the first light redistribution member 14 is 86 degrees to 94 degrees, the inclination angle θ1 is 47 degrees to 43 degrees. When the refractive index n is 1.46 and the tilt angle θ1 is 47 ° to 43 °, the first emission angle θin1 of light from the light emitting layer 4 is 15.2 ° to 16.9 °. When the refractive index n is 1.60 and the tilt angle θ1 is 47 ° to 43 °, the first emission angle θin1 is 17.8 ° to 19.8 °.

  That is, when the apex angle θ3 is 86 degrees to 94 degrees, light is redistributed by the light redistribution structure layer 12 by repeating the cycle, and the light distribution characteristic of the light from the light emitting layer 4 is the emission angle θin1 = 15 degrees The amount of light of 20 degrees is relatively increased, and the light emitted from the EL element 1 in the front direction can be increased.

Further, as a method of increasing the brightness in the front direction, it is possible to further increase the brightness in the front direction by increasing the amount of light that satisfies the emission angle θin1 of the formula (1) in the light distribution from the light emitting layer 4. .
In this case, the effect is further increased when the ratio of the light amount at the emission angle θin1 and the total light amount from the light emitting layer 4 is larger than the following equation (2).

The light distribution of the light emitting layer 4 is generally a perfect diffusion light distribution based on Lambert-Beer's Law (hereinafter referred to as a Lambert distribution).
FIG. 6 shows the relative integrated light amount for each emission angle θin1 from the light emitting layer 4 in the Lambert distribution.
The integrated light quantity at the emission angle θin1 is expressed by equation (3).

When the expression (4) is integrated in the range of the emission angle θin1 from 0 degrees to 90 degrees, 180 degrees is obtained. By dividing the expression (4) by 180 degrees, the light quantity at the emission angle θin1 and the total light quantity from the light emitting layer 4 are obtained. Can be calculated.
Here, the ratio of the light amount at the emission angle θin1 and the total light amount from the light emitting layer 4 is larger than the expression (2), so that the light emitted in the front direction of the EL element 1 can be increased from the Lambert distribution. It becomes.
Preferably, it becomes larger than the following formula (5), which makes it possible to increase the brightness of the EL element 1 in the front direction. In the formula (5), the front luminance improvement effect of the light redistribution sheet 7 is further increased by setting the coefficient to 1.2.

Regarding the light distribution from the light emitting layer 4, the ratio of the light quantity at the emission angle θin1 satisfying the expression (1) to the light quantity at the emission angle θin1 and the total light quantity from the light emitting layer 4 is larger than the expression (2). The amount of light emitted in the front direction of the EL element 1 increases. Further, light is redistributed by repeating the cycle by the light redistribution structure layer 12 having apex angles θ3 and θ4 = 86 degrees to 94 degrees, and the light redistribution sheet 7 is obtained with respect to the light distribution characteristics of the light from the light emitting layer 4. Accordingly, the amount of light emitted from the EL element 1 is relatively increased, and the light emitted from the EL element 1 in the front direction can be further increased.
On the other hand, as shown in FIGS. 4 and 5, only by the light distribution characteristic due to the light emitted from the first light redistribution sheet 7, an increase in the light amount at an emission angle of 15 degrees to 20 degrees cannot be obtained. The EL element 1 cannot increase the emitted light in the front direction.
In addition, when the apex angles θ3 and θ4 deviate from 86 degrees to 94 degrees, there is a problem that the emission light in the front direction is reduced.

FIG. 7 shows the light utilization efficiency of the light redistribution structure layer 12 having apex angles θ3 and θ4 = 86 degrees to 94 degrees for each emission angle θin1 from the light emitting layer 4, that is, for each incident angle to the light redistribution structure layer 12. Show.
The light use efficiency here refers to the ratio of light emitted to the outside of the EL element 1 by repeating the cycle of being incident on and reflected by the light redistribution structure layer 12, and the light reflectance in the EL element 1 is 80%. As a simulation. In this case, the direction of the light emitted to the outside is not relevant.
For example, about 85% of the light emitted from the light emitting layer 4 at the emission angle θin1 = 35 degrees can be emitted to the outside.

In the simulation result shown in FIG. 7, the light utilization efficiency exceeds 80% in the range of the emission angle θin1 = 25 degrees to 50 degrees, where the ratio of the light emitted from the light emitting layer 4 is emitted to the outside as the light utilization efficiency. High light utilization efficiency.
Therefore, with respect to the light distribution characteristics of the light emitted from the light emitting layer 4, the light utilization efficiency of the light redistribution structure layer 12 is further increased by increasing the light quantity in the range of the emission angle θin1 = 25 degrees to 50 degrees. Is possible.

  Further, in the relative integrated light amount for each emission angle θin1 of the light emitted from the light emitting layer 4 in the Lambert distribution shown in FIG. 6, the ratio of the relative integrated light amount in the region 200 where the emission angle θin1 = 25 degrees to 50 degrees is It is 42.5% with respect to the total light quantity in the Lambert distribution. For this reason, the light distribution efficiency of the light emitted from the light emitting layer 4 can be made larger than the Lambert distribution by making the ratio of the light quantity in the range of the emission angle 25 degrees to 50 degrees 42.5% or more. It becomes possible.

Further, as a method for increasing the light utilization efficiency, it is preferable to add a light diffusion function to the light redistribution sheet 7 or the bonding layer 10.
By adding the light diffusion function, the light distribution from the light emitting layer 4 can be changed. In particular, light having a high angle of emission angle θin1 from the light emitting layer 4 exceeding 50 degrees can be shifted to 50 degrees or less by the light diffusion function provided in the optical path.
As shown in FIG. 7, the light utilization efficiency of the light redistribution structure layer 12 tends to decrease for light having an incident angle, that is, light having an emission angle θin1 from the light emitting layer 4 exceeding 50 degrees. Therefore, by adding a light diffusion function using light obtained by shifting the emission angle θin1 from the light emitting layer 4 to within 50 degrees, the emission angle θin1 has an emission angle equivalent to that of high-angle light exceeding 50 degrees. Light can be obtained and light utilization efficiency can be improved.

Such a light diffusion function is preferably provided in the light redistribution structure layer 12.
That is, the light redistribution structure layer 12 has low light use efficiency of light at a specific angle. For example, as shown in FIG. 7, a region where the incident angle, that is, the emission angle θin1 from the light emitting layer 4 is 0 degrees to 10 degrees, and 70 degrees to 85 degrees is a region with low light utilization efficiency. Therefore, it is preferable to provide a light diffusing function in the light redistribution structure layer 12 because the light utilization efficiency in the region where the light utilization efficiency is small can be further increased.

  Here, as the material of the light redistribution sheet 7, various materials having light transmittance with respect to the wavelength of the light B0 emitted from the light emitting layer 4 can be used, for example, a plastic material for an optical member, etc. Can be used. Examples of such plastic materials include polyester resins, acrylic resins, polycarbonate resins, polystyrene resins, MS (acrylic and styrene copolymer) resins, polymethylpentene resins, thermoplastic resins such as cycloolefin polymers, and polyesters. Transparent resins such as radiation curable resins made of oligomers such as acrylates, urethane acrylates, epoxy acrylates, or acrylates are used.

In addition, the light redistribution sheet 7 may have fine particles dispersed in these resins as a diffusing agent according to desired optical characteristics.
As the fine particles, particles made of an inorganic oxide, transparent particles made of a resin, or the like can be used. For example, examples of the inorganic oxide include silica, alumina, and titanium oxide. In addition, as resins, acrylic, styrene, styrene acrylic and its cross-linked product, melamine-formalin condensate, PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxy resin), FEP (tetrafluoroethylene-hexafluoropropylene copolymer) , Fluorine-containing polymers such as PVDF (polyfluorovinylidene) and ETFE (ethylene-tetrafluoroethylene copolymer), and silicone resins.
These fine particles may be used as a mixture of two or more kinds.

The light redistribution sheet 7 can be molded, for example, by pouring and solidifying the above-mentioned material into a preformed mold. The mold uses diamond tools having various lens shapes, and the first light redistribution surface 16 and the second light redistribution member 15 of the first light redistribution member 14 are formed on a copper plated mold. It can be manufactured by cutting a portion corresponding to the shape of the second light redistribution surface 17.
The light redistribution sheet 7 can be molded by extrusion molding, injection molding, UV molding, or the like using a thermoplastic resin or an ultraviolet curable resin, in addition to a method of molding by casting solidification. At this time, the light redistribution sheet 7 may be integrally molded, for example, divided into the first light redistribution member 14, the second light redistribution member 15, and the base material 11, and then molded. You may make it assemble to. In any case, a diffusing agent such as a filler that exhibits a light diffusing function can be dispersed therein and molded.
Further, in the light redistribution sheet 7, ultrafine particles such as antimony-containing tin oxide (ATO) or tin-containing indium oxide (ITO), which are conductive fine particles, may be dispersed as an antistatic agent. By dispersing the antistatic agent, the antifouling property of the light redistribution sheet 7 can be improved.

In the light redistribution sheet 7, when the light redistribution structure layer 12 and the base material 11 are separately molded by UV molding or the like, cellulose triacetate, polyester, polyamide, polyimide, polypropylene, polymethylpentene, A stretched or unstretched transparent film made of a thermoplastic resin such as polyvinyl chloride, polyvinyl acetal, polymethyl methacrylate, polycarbonate, or polyurethane can also be used.
The thickness of the substrate 11 is preferably 50 to 300 μm from the viewpoint of workability and handling, although it depends on characteristics such as rigidity of the material used.

For the assembly of the light redistribution structure layer 12 and the base material 11, the same adhesive, adhesive, double-sided tape and the like as those of the bonding layer 10 described above can be used. In order to firmly bond the light redistribution structure layer 12 and the base material 11, a primer layer having high adhesion to both materials is provided between the light redistribution structure layer 12 and the base material 11, or light redistribution is performed. A function of a primer layer may be added to the structural layer 12, or an easy adhesion process such as a corona discharge process may be performed.
Moreover, in the illumination device, the display device, and the liquid crystal display device according to the present embodiment, the use efficiency of light can be improved by providing the EL element 1 according to the present embodiment described above.

  As described above, according to the EL element 1 according to the present embodiment, a voltage is applied between the anode 5 and the cathode 6 of the light emitting structure 8 to emit light BO from the light emitting layer 4. The light B0 emitted from the light emitting layer 4 passes through the first substrate 2 and enters the light redistribution sheet 7. In the light redistribution sheet 7, a part of the light B 0 from the light emitting layer 4 is transmitted to the outside as transmitted light B 2, and the remaining light B 1 is reflected into the EL element 1. The reflected light B <b> 1 becomes light B <b> 3 directed toward the light reflecting layer 9 (cathode 6), is incident on the light reflecting layer 9, reflected, and becomes light B <b> 4 again directed toward the light redistribution sheet 7.

The reflected light B4 is again transmitted through the first substrate 2 and is incident on the light redistribution sheet 7. However, a part of the reflected light B4 becomes transmitted light B2 depending on the incident angle to the light redistribution sheet 7. The light is emitted to the outside of the distribution sheet 7 and the remaining light is reflected into the EL element 1 again as reflected light B1.
Then, the reflected light path of the light B1, the light B3, and the light B4 is repeated a plurality of times until the light B1 reflected again becomes the transmitted light B2 that passes through the light redistribution sheet 7. This makes it possible to align the traveling direction of the light B2 that has passed through the light redistribution sheet 7 in the irradiation direction F, thereby enhancing the directivity of the EL element 1 and improving the light utilization efficiency. .

As described above, according to the EL element 1 according to the present embodiment, the light redistribution sheet 7 has the light redistribution structure layer 12 provided on the light emitting side in the first direction along the surface of the first substrate 2. A first redistribution member 14 having a pair of first light redistribution surfaces 16 extending in X and having an apex angle θ3 formed in the range of 86 to 94 degrees, and 80 degrees to the first direction X It has a pair of second light redistribution surfaces 17 extending in the second direction Y intersecting at an angle φ of 90 degrees and having an apex angle θ4 formed so as to intersect each other in the range of 86 degrees to 94 degrees. Since the second redistribution member 15 is arranged and provided, the light emitted from the light emitting layer 4 has a predetermined light distribution, so that the directivity of the light can be improved. The efficiency of extracting external light from the light redistribution sheet 7 can be improved by providing .
Moreover, the illumination device, the display device, and the liquid crystal display device according to the present embodiment can improve the light use efficiency by including the EL element 1 described above.

As described above, the EL element 1 according to the embodiment of the present invention and the lighting device, the display device, and the liquid crystal display device including the EL element 1 have been described. However, the present invention is not limited to the above-described embodiment, and departs from the spirit thereof. It is possible to change appropriately within the range not to be.
For example, this embodiment is a typical example of the light redistribution sheet 7, and materials, structures, processes, and the like other than those used in this embodiment are used unless the characteristics of the EL element 1 of this embodiment are impaired. It is possible to configure the light redistribution sheet 7 by adopting it.
For example, the light redistribution structure layer 20 according to the modification is formed at a predetermined pitch as shown in FIG. 8 instead of the arrangement structure of the first light redistribution member 14 and the second light redistribution member 15. The convex first prism 21 and the convex second prism 22 formed in a direction substantially orthogonal to the first prism 21 may be combined and arranged.

The prism sheet in which the prisms are arranged in one direction can control the polarization of the light distribution of the incident light B1 in the direction in which the prisms are arranged by the slope of the prism. Therefore, when the prisms arranged in one direction are used, the light distribution can be adjusted one-dimensionally. However, when the EL element 1 is used for illumination, it is necessary to adjust the light distribution distribution at least two-dimensionally. That is, for example, when there is no need to irradiate a specific direction depending on the installation location of the lighting device, a luminance enhancement characteristic in the front direction is required instead of a wide light distribution characteristic.
Alternatively, when the light B1 incident on the prism sheet has an asymmetric light distribution, the light distribution of the light B2 emitted from the illumination device to the outside is required to be a symmetric light distribution. In this case, it is difficult to polarize the light distribution of the light B2 emitted from the illumination device into a symmetrical light distribution by one-dimensional adjustment, and two-dimensional adjustment is required.

In such a case, as shown in FIG. 8, the light redistribution structure layer 20 of the light redistribution sheet 19 is formed in the form of a cross prism in which prisms 21 and 22 are arranged substantially orthogonally, thereby allowing light to be two-dimensionally distributed. Adjustment is possible. Therefore, it is possible to adjust to an appropriate light distribution without adding a new lens sheet. And the illuminating device using the EL element 1 provided with such a light redistribution structure layer 20 can achieve weight reduction, thickness reduction, and cost reduction.
Further, in order to deflect the light B1 incident on the light redistribution structure layer 20 in substantially the same direction and collect the light in an arbitrary direction, the first prism 20 and the second prism The slope of 21 is preferably a flat surface.
The shapes of the first prism 21 and the second prism 22 may be the same, may be similar shapes with different sizes, or may be different.

Furthermore, as illustrated in FIGS. 9 and 10, the light redistribution structure layer 24 of the light redistribution sheet 7 has a polygonal pyramidal convex lens 25 or a polygonal pyramidal concave lens 26 having a polygonal base, for example, a quadrangle, at its apex. You may employ | adopt the form arrange | positioned without gap so that the certain top parts 25a and 26a may be arranged in the 1st direction X and the 2nd direction Y.
The polygonal pyramid convex lens 25 or the polygonal pyramidal concave lens 26 can be arranged with a gap interposed therebetween, but the light redistribution structure can be arranged by eliminating the gap between the polygonal pyramidal convex lens 25 and the polygonal pyramidal concave lens 26. Since the flat portions that do not contribute to the deflection of the incident light B1 on each inclined surface (the first light redistribution surface 27 and the second light redistribution surface 28) in the layer 24 can be eliminated, the light extraction efficiency is higher. The EL element 1 can be realized. In addition, by arranging the lenses 26 and 27 without any gaps, a fine structure due to the flat portion is not formed, so that it is possible to prevent color unevenness due to light diffraction.

In order to arrange the polygonal pyramidal convex lens 25 or the polygonal pyramidal concave lens 26 without a gap, for example, as shown in FIGS. 11 (a), (b), and (c), the bottom surfaces 27, 28, and 29 of the lens are formed as regular hexagons, squares, It is preferable that they have arbitrary substantially identical shapes such as equilateral triangles and are regularly arranged. Making the shapes of the bottom surfaces 27, 28, and 29 substantially the same makes the size and shape of the light redistribution structure layer 24 substantially the same, thereby realizing the EL element 1 in which no in-plane brightness unevenness occurs. It becomes possible.
For example, in the case where the bottom surface 27 is a regular hexagon in FIG. 11A, the adjacent portion between the bottom surfaces 27 is not a straight line but a more complicated zigzag line, and thus when the EL element 1 is provided with a pixel pattern. It is more preferable because it is possible to prevent moiré caused by interference between the shape of the connecting portion between the bottom surfaces 27 and the pixel pattern of the EL element 1.

Further, the light redistribution structure layer 24 may be configured by arranging a plurality of polygonal pyramidal convex lenses or polygonal pyramidal concave lenses having different shapes. In this case, the bottom surfaces 27, 28, and 29 of different lenses may have the same shape or different shapes. Even when the shapes of the bottom surfaces 27, 28, and 29 are different, it is preferable that the bottom surfaces are arranged without gaps, for example, as shown in FIG. 12 by combining the regular octagon 30 and the square 31.
FIG. 9 shows a configuration in which the light redistribution structure layer 24 of the light redistribution sheet 7 is arranged without a gap so that the bottom surface 28 becomes a quadrangular pyramidal convex lens 25.

  When it is required to make the light distribution of the light B2 emitted from the EL element 1 symmetrical, a regular quadrangular pyramid in which the bottom surface 28 is formed in a substantially square shape and the inclination angles of the four inclined surfaces are substantially the same. It is preferable that the polygonal pyramid convex lens 25 has a shape.

  When it is required to make the light distribution of the light B2 emitted from the EL element 1 asymmetric, the bottom surface 28 has a long side (for example, the first direction X) and a short side (for example, the second direction Y). You may form in the rectangular pyramid convex lens 25 made into the rectangle. By making the bottom surface 28 rectangular, the inclination angle of the two inclined surfaces facing each other on the short side is different from the inclination angle of the two inclined surfaces facing each other on the long side, so that the light B2 emitted from the EL element 1 Can be made asymmetric in the first direction X and the second direction Y.

FIG. 10 shows a configuration in which the light redistribution structure layer 24 of the light redistribution sheet 7 is arranged without gaps as a quadrangular pyramidal concave lens 26 having a bottom surface 28 forming a square shape. The light redistribution structure layer 24 by the quadrangular pyramid concave lens 26 is formed to take out the light B1 incident on the light redistribution structure layer 24 so as to be emitted in the irradiation direction F that is vertically upward of the light redistribution sheet 7. ing.
Note that when the light redistribution structure layer 24 is arranged by the quadrangular pyramidal concave lenses 26, the top portion of the light redistribution structure layer 24 which is the highest position is not a point but a quadrangular ridgeline, so that the abrasion resistance is improved. This is preferable.

Further, when there is a demand to form a symmetrical distribution of the light B2 emitted from the EL element 1, the bottom surface 28 is formed in a substantially square shape, and the inclination angles of the four inclined surfaces of the quadrangular pyramidal concave lens 26 are substantially the same. It is preferable that
Further, when there is a demand to form an asymmetric distribution of the light B2 emitted from the EL element 1, the bottom surface 28 may be formed as a rectangular pyramid concave lens 26 having a long side and a short side. . By making the bottom surface 28 rectangular, the inclination angle of the inclined surface in the short side direction of the quadrangular pyramidal concave lens 26 is different from the inclination angle of the inclined surface in the long side direction, so that the light distribution of the light B2 emitted from the EL element 1 is distributed. Can be formed asymmetrically between the long side direction and the short side direction.
For the same reason, when the light redistribution structure layer 24 is configured by arranging prism lenses or quadrangular pyramid lens shapes, the top of the tip is cut to be substantially flat to have a quadrangular pyramid shape or rounded shape. May be formed into a convex curved surface.

Furthermore, when the light redistribution structure layer 24 is constituted by the prism lenses 21 and 22 as shown in FIG. 8 or the quadrangular pyramid convex lens 25 as shown in FIG. 9, two inclined surfaces forming a prism shape or a quadrangular pyramid shape. It is also possible to curve the four inclined surfaces forming a convex curved surface or a concave curved surface. When each inclined surface in the light redistribution structure layer 24 is curved into a convex curved surface shape or a concave curved surface shape, the first and second lights of the light redistribution structure layer 24 are compared with the case where each inclined surface is linear. The light B1 incident on the redistribution surfaces 16, 17, 27, and 28 can be deflected over a wide range of angles.
In addition, when the light B1 incident on the light redistribution structure layer 24 is changed in the angle with respect to the viewing direction, if a problem of color misregistration that changes in color occurs, the inclined surface of the light redistribution structure layer 24 is changed. By deflecting the light B0 from the light emitting layer 4 at a wide range of angles by curving into a convex or concave shape, the color of the light B0 of the light emitting layer 4 can be made uniform without depending on the angle with respect to the viewing direction. .

  The width of the single concave portion or convex portion formed on the light redistribution structure layer 24 on the surface of the base material 11 is within a range of 20 μm to 200 μm so that diffracted light hardly occurs and is difficult to be visually recognized from the irradiation direction F. It is desirable to set. In the case of a prism lens, this width is the width of the bottom of a triangular section, and in the case of a quadrangular pyramid, the width of one side of the bottom surface 28.

Next, examples of the present invention will be described.
Example 1
A PET film (thickness: 188 μm) was used as the substrate 11, and a light redistribution sheet 19 shown in FIG. 8 was prepared by a UV molding method using a UV curable resin having a refractive index of 1.52. In the light redistribution sheet 19, the apex angles θ3 and θ4 are 94 degrees.
In this case, the emission angle θin1 is 16.3 degrees from the equation (1).
The light redistribution sheet 19 was disposed in the EL element 1 instead of the light redistribution sheet 7, and the front luminance of the EL element 1 was measured with a luminance meter (manufactured by TOPCOM: SR-3A).
Note that the ratio between the light amount of the first emitted light having the emission angle θin1 of the EL element 1 and the total light amount emitted from the light emitting layer 4 was 0.020. (The value of the formula (2) was 0.017.)

(Comparative Example 1)
A PET film (thickness: 188 μm) was used as the substrate 11, and a light redistribution sheet 19 shown in FIG. 8 was prepared by a UV molding method using a UV curable resin having a refractive index of 1.52. In the light redistribution sheet 19, the apex angles θ3 and θ4 were each 96 degrees.
In this case, the injection angle θin1 is 15.9 degrees from the equation (1).
The light redistribution sheet 19 was placed on the EL element 1, and the front luminance of the EL element 1 was measured with a luminance meter (manufactured by TOPCOM: SR-3A).
Note that the ratio between the light amount of the first emitted light having the emission angle θin1 of the EL element 1 and the total light amount emitted from the light emitting layer 4 was 0.020. (The value of the formula (2) was 0.017.)

(Example 2)
A PET film (thickness: 188 μm) was used as the substrate 11, and a light redistribution sheet 19 shown in FIG. 8 was prepared by a UV molding method using a UV curable resin having a refractive index of 1.52. In the light redistribution sheet 19, the apex angles θ3 and θ4 were each 86 degrees.
In this case, the injection angle θin1 is 18.2 degrees from the equation (1).
The light redistribution sheet 19 was placed on the EL element 1, and the front luminance of the EL element 1 was measured with a luminance meter (manufactured by TOPCOM: SR-3A).
Note that the ratio between the light amount of the first emitted light having the emission angle θin1 of the EL element 1 and the total light amount emitted from the light emitting layer 4 was 0.020. (The value of the formula (2) was 0.017.)

(Comparative Example 2)
A PET film (thickness: 188 μm) was used as the substrate 11, and a light redistribution sheet 19 shown in FIG. 8 was prepared by a UV molding method using a UV curable resin having a refractive index of 1.52. In the light redistribution sheet 19, the apex angles θ3 and θ4 are 84 degrees.
In this case, the injection angle θin1 is 18.7 degrees from the equation (1).
The light redistribution sheet 19 was disposed on the EL element 1, and the front luminance of the EL element 1 was measured with a luminance meter (manufactured by TOPCOM: SR-3A).
Note that the ratio between the light amount of the first emitted light having the emission angle θin1 of the EL element 1 and the total light amount emitted from the light emitting layer 4 was 0.020. (The value of the formula (2) was 0.017.)

(Comparative Example 3)
A PET film (thickness: 188 μm) was used as the substrate 11, and a light redistribution sheet 19 shown in FIG. 8 was prepared by a UV molding method using a UV curable resin having a refractive index of 1.52. In the light redistribution sheet 19, the apex angles θ3 and θ4 are 94 degrees.
In this case, the emission angle θin1 is 16.3 degrees from the equation (1).
The light redistribution sheet 19 was disposed on the EL element 1, and the front luminance of the EL element 1 was measured with a luminance meter (manufactured by TOPCOM: SR-3A).
The ratio of the amount of first emitted light having the emission angle θin1 of the EL element 1 to the total amount of light emitted from the light emitting layer 4 was 0.015. This value departs from the present invention in that it does not exceed 0.017, which is the value of equation (2).

(Comparative Example 4)
A PET film (thickness: 188 μm) was used as the substrate 11, and a light redistribution sheet 19 shown in FIG. 8 was prepared by a UV molding method using a UV curable resin having a refractive index of 1.52. In the light redistribution sheet 19, the apex angles θ3 and θ4 were each 86 degrees.
In this case, the injection angle θin1 is 18.2 degrees from the equation (1).
The light redistribution sheet 19 was placed on the EL element 1, and the front luminance of the EL element 1 was measured with a luminance meter (manufactured by TOPCOM: SR-3A).
The ratio of the amount of first emitted light having the emission angle θin1 of the EL element 1 to the total amount of light emitted from the light emitting layer 4 was 0.015. This value departs from the present invention in that it does not exceed 0.017, which is the value of equation (2).

(Example 3)
A PET film (thickness: 188 μm) was used as the substrate 11, and a light redistribution sheet 19 shown in FIG. 8 was prepared by a UV molding method using a UV curable resin having a refractive index of 1.52. In the light redistribution sheet 19, the apex angles θ3 and θ4 are 94 degrees.
In this case, the emission angle θin1 is 16.3 degrees from the equation (1).
The light redistribution sheet 19 was placed on the EL element 1, and the front luminance of the EL element 1 was measured with a luminance meter (manufactured by TOPCOM: SR-3A).
Note that the ratio between the light amount of the first emitted light having the emission angle θin1 of the EL element 1 and the total light amount emitted from the light emitting layer 4 was 0.021. (The value of the formula (2) was 0.017.)

Table 1 shows the measurement results of the front luminance of Examples 1 to 3 and Comparative Examples 1 to 4 described above. In addition, each front brightness | luminance of these Examples and a comparative example is a relative value when the front brightness | luminance of the EL element 1 in the state which does not provide the light redistribution sheet 19 is set to 1.
The reflectivity of each EL element 1 is 50%.

From the results shown in Table 1, when Examples 1 to 3 and Comparative Examples 1 to 4 are compared, the apex angles θ3 and θ4 in the shape of the light redistribution sheet 19 according to each example are set to 86 to 94 degrees. Further, it was confirmed that the front luminance increase effect was further improved as compared with Comparative Examples 1 to 4.
Moreover, when Examples 1-2 and Comparative Examples 3-4 are compared, the light quantity of the 1st emission light which has the emission angle (theta) in1 which satisfy | fills (1) Formula, and it injects from the light emitting layer 4 with the shape of a present Example. It was confirmed that the effect of increasing the front luminance was improved by increasing the ratio with respect to the total light quantity to be larger than the expression (2).

  When Examples 1 and 2 were compared with Example 3, it was confirmed that, by substituting into the formula (5), the front brightness was improved to 1.5, and the effect was further increased.

1 EL element 2 First substrate (translucent substrate)
3 Second substrate 4 Light emitting layer 5 Anode 6 Cathode (light reflection layer)
7 Light Redistribution Sheet 8 Light-Emitting Structure 9 Light Reflective Layer 10 Bonding Layer 11 Base Material 12, 20 Light Redistribution Structure Layer (Roughness)
14 First light redistribution member 15 Second light redistribution member 16 First light redistribution surface 17 Second light redistribution surface 21 First prism 22 Second prism

Claims (8)

An EL device comprising a translucent substrate, and a light emitting layer provided on one surface of the translucent substrate and sandwiched between an anode and a cathode,
A light redistribution sheet that is provided on the other surface facing the one surface of the translucent substrate and emits incident light;
A light reflecting layer provided on the opposite side of the light redistribution sheet with respect to the light emitting layer,
The light redistribution sheet has a light redistribution structure;
The light redistribution structure extends in a first direction along the translucent substrate and is formed to be inclined so that the angle of the top formed by intersecting each other is 86 degrees or more and 94 degrees or less. A first light redistribution surface of
The top portion extending in the second direction intersecting with the first direction at an angle of 80 degrees or more and 90 degrees or less and tilted so that the top angle formed by intersecting each other is 86 degrees or more and 94 degrees or less. And a pair of second light redistribution surfaces formed
The EL, wherein the light emitting layer has a ratio of the amount of the first emitted light having an emission angle θin1 satisfying the following formula (1) and the total amount of light emitted from the light emitting layer larger than the following formula (2): element.

Where θ1: the inclination angle of the first light redistribution surface and the second light redistribution surface,
θin: emission angle of light emitted from the light emitting layer,
n: Refractive index of the light redistribution sheet. An EL device comprising a translucent substrate, and a light emitting layer provided on one surface of the translucent substrate and sandwiched between an anode and a cathode,
A light redistribution sheet that is provided on the other surface facing the one surface of the translucent substrate and emits incident light;
A light reflecting layer provided on the opposite side of the light redistribution sheet with the light emitting layer in between,
The light redistribution sheet has a light redistribution structure,
The light redistribution structure extends in a first direction along the translucent substrate and is formed to be inclined so that an angle of a top portion formed by intersecting each other is 86 degrees or more and 94 degrees or less. A first light redistribution surface of
The top portion extending in the second direction intersecting with the first direction at an angle of 80 degrees or more and 90 degrees or less and tilted so that the top angle formed by intersecting each other is 86 degrees or more and 94 degrees or less. And a pair of second light redistribution surfaces formed
The light emitting layer is characterized in that the amount of second emitted light having an emission angle θin2 in a range satisfying the following expression (3) is 42.5% or more of the total amount of light emitted from the light emitting layer. EL element.

Where θin2 is an emission angle of light emitted from the light emitting layer.   The pair of first light redistribution surfaces serves as a first light redistribution member having a prism shape with a substantially triangular cross section, and the pair of second light redistribution surfaces has a prism shape with a substantially triangular cross section. The EL element according to claim 1, wherein the EL element is a member.   The EL device according to claim 1, wherein the light redistribution sheet or a bonding layer of the light redistribution sheet has a light diffusion function.   The EL device according to claim 4, wherein the light redistribution structure portion of the light redistribution sheet has a light diffusion function.   An illumination device comprising the EL element according to claim 1 as a light emitting unit.   A display apparatus comprising the EL element according to claim 1, wherein the EL element is configured to be pixel-driven. A liquid crystal display device comprising an image display element,
A liquid crystal comprising the EL element according to any one of claims 1 to 5 or the illumination device according to claim 6 provided on a back surface of the image display element. Display device.

Images