JP6136096B2 - LIGHTING DEVICE, LIQUID CRYSTAL DISPLAY DEVICE, DISPLAY DEVICE, AND LIGHTING DEVICE MANUFACTURING METHOD - Google Patents

Description

  The present invention includes an EL device (electroluminescence device) used for a flat panel display, a backlight for liquid crystal, a light source for illumination, an electric decoration, a light source for signage, and the like, and an illumination device and a liquid crystal display using a light extraction member The present invention relates to a device and a display device.

  In general, an organic EL element has a structure in which a light emitting layer containing a fluorescent organic compound is sandwiched between an anode and a cathode on a translucent substrate. Then, a DC voltage is applied to the anode and the cathode, electrons and holes are injected into the light emitting layer and recombined to generate excitons, and light emission when the excitons are deactivated is used. It leads to light emission.

  Conventionally, in these EL elements, when the light emitted from the light emitting layer is emitted from the translucent substrate, a part of the light is totally reflected on the translucent substrate and is lost. . The light extraction efficiency at this time is generally said to be about 20%. For this reason, there is a problem that the higher the luminance is, the more input power is required. In this case, the load on the EL element is increased and the reliability of the element itself is lowered.

  In order to improve the external extraction efficiency of light, a method has been proposed in which fine irregularities are formed on an element substrate and a light beam lost due to total reflection is extracted to the outside. For example, it has been proposed to form a microlens array in which a plurality of microlens elements are arranged in a plane on one surface of a translucent substrate (see Patent Document 1).

JP 2002-260845 A

  However, in the conventional EL element described in Patent Document 1, even if fine microlenses are arranged in close contact with each other, a flat surface gap is generated between the microlenses that are in contact with each other. The light emitted from is reflected. For this reason, the above-described EL element is not sufficient for improving the light extraction efficiency and suppressing the chromaticity change due to the emission angle of the emitted light.

  The present invention has been made in view of such circumstances, and is intended to improve the light extraction efficiency by optimizing the light extraction efficiency and to improve the change in chromaticity coordinates due to the emission angle of the emitted light. It is an object of the present invention to provide an illumination device, a liquid crystal display device, and a display device having advantageous EL elements.

In order to solve the above-described problems, the present invention proposes the following means.
That is, the illumination device according to the present invention includes a light emitting member and a light extraction member including a light deflection element that guides and emits the light emitted from the light emitting unit.
The light deflection element is formed by arranging a large number of fine convex portions without any gaps on the light exit surface,
The convex curved portion is formed as a convex curved surface in a longitudinal sectional view, the displacement in the width direction of a large number of the convex curved surfaces is x, and the height shape of the convex curved surface is f (x),
F (x) is represented by an irregular function,
In the function f (x) of the height shape of the convex curved surface in the longitudinal sectional view of the light deflection element,
When the maximum value is f (x) _max and the minimum value is f (x) _min ,
Δf (x) = f (x) _max −f (x) _min
The Δf (x) satisfies the following formula (1),
When g (x) is a function obtained by extracting an inflection point in the function f (x) of the height shape of the convex curved surface,
In the function g (x), the absolute value | dg (x) / dx | _Ave of the average gradient of the gradient between two adjacent inflection points satisfies the following equation (2):
When the average gradient | dg (x) / dx | _Ave is changed, the maximum change in the chromaticity coordinates u ′ and v ′ in the range of 0 to 80 degrees in the measurement visual field when the light extraction member is not used The amount ΔEu′v ′ = √ {(umax−umin) ² + (vmax−vmin) ² } is set to 1.00, and the reduction rate with respect to the maximum value of the relative color difference is 50% or more.
0.001 mm ≦ Δf (x) ≦ 0.300 mm (1)
2 ≦ | dg (x) / dx | _Ave ≦ 8 (2)
A manufacturing method of a lighting device according to the present invention is a manufacturing method of a lighting device described in any of the above,
The light extraction member can be molded by solidifying the material with a mold.
In the manufacturing method of the lighting device according to the present invention, the mold may be formed by randomly arranging convex curved portions using cutting, laser processing, or sand plasting.
An illuminating device according to the present invention includes a light emitting member and a light extraction member including a light deflecting element that guides and emits light emitted from the light emitting unit. The convex curved portions are formed so as to be arranged without gaps, and the convex curved portions are formed as convex curved surfaces in a longitudinal sectional view, where x is the displacement in the width direction of the convex curved surface, and f ( and x), f (x) is Ru can Rukoto is represented by irregular functions.
According to the illumination device of the present invention, the displacement in the width direction of a large number of fine convex curved surfaces forming the light deflection element is x, and the height shape of the convex curved surface at the displacement x is expressed by an irregular function f (x). As a result, the exit surface of the light deflection element can be formed by a convex curved surface having an irregular height, and the external extraction efficiency of light emitted from the light emitting means and the change in chromaticity coordinates due to the exit angle are improved. This makes it possible to obtain a lighting device with high light utilization efficiency.

  Further, by configuring a liquid crystal display device or a display device including the illumination device according to the present invention, in addition to obtaining the above-described light characteristics, a liquid crystal display device and a display device having high light utilization efficiency and design properties Can be provided.

In the illumination device according to the present invention, the maximum value is f (x) _max and the minimum value is f (x) _{min in} the function f (x) of the height of the convex curved surface in the longitudinal sectional view of the light deflection element. When
Δf (x) = f (x) _max −f (x) _min
Δf (x) preferably satisfies the following expression (1).
0.001 mm ≦ Δf (x) ≦ 0.300 mm (1)
In the illuminating device according to the present invention, the difference Δf (x) between the maximum value and the minimum value of the heights of the many convex curved surfaces of the light deflection element is set within the range of the above formula (1), so that the light deflection action by the light deflection element. Therefore, there is an advantage that a suitable injection characteristic can be exhibited without generating wavelength dependency, and the uneven shape of the convex curved surface is not visually confirmed.
On the other hand, if the value of Δf (x) is smaller than 0.001 mm, the wavelength region is in the visible light region, which is not preferable because the light deflection action by the light extraction member has wavelength dependency. Further, if the value of Δf (x) is larger than 0.300 mm, the uneven shape of the convex curved surface of the light deflection element by the light extraction member is easily visually recognized, which is not preferable.

Further, the illumination device according to the present invention has two adjacent points in the function g (x), where g (x) is a function obtained by extracting the inflection point in the function f (x) of the cross-sectional height shape of the light deflection element. the absolute value of the average slope ratio of slope between _{| dg (x) / dx |} Ave preferably satisfies the following formula (2).
1 ≦ | dg (x) / dx | _Ave ≦ 8 (2)
If the absolute value | dg (x) / dx | _Ave of the average gradient is within the range of the above equation (2), the relative color difference gradually decreases and improves as the absolute value increases. On the other hand, if the absolute value of the average gradient | dg (x) / dx | _Ave is less than 1, the relative color difference is large, and if it is greater than 8, the improvement effect of the color difference does not proceed any more and is almost constant, and the convex curve Part molding becomes difficult.

Since the reduction rate of the relative color difference is preferably large, it is preferably in the range of 2 ≦ | dg (x) / dx | _Ave ≦ 8 where the reduction rate with respect to the maximum value of the relative color difference is 50% or more. Is desirable. Further, considering that the moldability becomes difficult when the average gradient | dg (x) / dx | _Ave increases, the effect of improving the color difference hardly changes 2 ≦ | dg (x) / dx | _Ave ≦ More preferably, it is within the range of 4.

Moreover, it is preferable that the light deflection element is formed by arranging a large number of convex curved portions at random.
The light deflection element formed on the light extraction member is expressed by an irregular function f (x) by using a die forming machined by a random number program, a laser machining by a random number program, a sand plast process or the like. In addition, a large number of convex curved portions can be randomly arranged.
Moreover, it is preferable that the light emission means of the illuminating device by this invention is an EL element.

A liquid crystal display device according to the present invention includes any one of the illumination devices described above and a liquid crystal image display element disposed on the light emission surface side of the illumination device.
According to the present invention, by making the light emitted from the light emitting means incident on the light extraction member, it is possible to improve the extraction efficiency to the outside and improve the change in chromaticity coordinates due to the emission angle. The use efficiency of the liquid crystal display is high.

A display device according to the present invention includes any one of the illumination devices described above and an image display element disposed on the light emission surface side of the illumination device.
According to the present invention, by making the light emitted from the light emitting means incident on the light extraction member, it is possible to improve the extraction efficiency to the outside and improve the change in chromaticity coordinates due to the emission angle. , Increase the light intensity of the display and reduce the color difference, and high usage efficiency

According to the illuminating device of the present invention, the displacement in the width direction of a large number of convex portions forming the light deflection element is x, and the height shape of the convex curved surface in the longitudinal section of the convex portion at the displacement x is f (x ), The height-shaped function f (x) is represented by an irregular function, so that the exit surface of the light deflection element is formed by the irregular-shaped function f (x) of the convex curved surface. Therefore, it is possible to improve the change in chromaticity coordinates due to the external light extraction efficiency and the emission angle, and to obtain an illumination device with high light utilization efficiency.
Further, by configuring a liquid crystal display device or a display device including the illumination device according to the present invention, in addition to obtaining the above-described light characteristics, a liquid crystal display device and a display device having high light utilization efficiency and design properties Can be obtained.

It is a schematic longitudinal cross-sectional view of the illuminating device which laminated | stacked the light extraction sheet | seat on the EL element by embodiment of this invention. It is a schematic longitudinal cross-sectional view of the EL element which does not use a light extraction sheet. It is explanatory drawing which shows the cross-sectional height shape of the convex curve by the longitudinal cross-sectional view of the light deflection | deviation element of the light extraction sheet | seat by embodiment of this invention. The characteristic of the light extraction sheet | seat in the illuminating device by embodiment is shown, Comprising: (a) is the value of the average inclination | tilt | dg (x) / dx | _Ave of the cross-sectional height shape of the convex curved surface of a light deflection | deviation element. FIG. 6B is a graph showing the change in relative color difference when the average gradient | dg (x) / dx | _Ave is changed. FIG.

Hereinafter, an illumination device according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows an illuminating device 10 according to an embodiment of the present invention, which is an EL element 101 (electroluminescence element) as a light emitting means and a light extraction member that is laminated on the light emitting surface side. The light extraction sheet 7 is schematically configured.
In FIG. 1, an EL element 101 is composed of a first substrate 1A, a second substrate 1B, and a light emitting structure 100 sandwiched between the first and second substrates 1A and 1B. . The light emitting structure 100 includes a light emitting layer 2, an anode 3 bonded to the first substrate 1A side of the light emitting layer 2, and a cathode 4 bonded to the second substrate 1B side of the light emitting layer 2. Has been.

In the light emitting structure 100, the light emitting layer 2 emits light by applying a voltage to the anode 3 and the cathode 4. The light emitting structure 100 includes the light emitting layer 2, the anode 3, and the cathode 4, and various conventionally known structures can be adopted as the light emitting structure 100 in addition to the above structure.
The light extraction sheet 7 includes a sheet-like base material 8, an adhesive layer 6 for bonding the base material 8 to the first substrate 1 </ b> A of the EL element 101, and the EL element 101 with respect to the base material 8. The light deflection element 5 is formed by laminating a plurality of light emitting convex curved portions 5a that are joined to the opposite surface and have a convex curved surface in longitudinal section. In FIG. 1, the light emitted from the EL element 101 is deflected through the light deflection element 5 of the light extraction sheet 7 and emitted in the F direction.

Next, each component of the illuminating device 10 by this embodiment is demonstrated.
The light emitting layer 2 of the light emitting structure 100 in the EL element 101 may be a white light emitting layer, for example, or may be a light emitting layer of blue, red, yellow, green, or the like. In the case of forming a white light emitting layer, the structure of the light emitting layer 2 is, for example, ITO / CuPc (copper phthalocyanine) / α-NPD doped with rubrene 1% / dinactylanthracene doped with perylene 1% / Alq3 / lithium fluoride / What is necessary is just to set it as Al as a cathode.

  However, the light emitting layer 2 is not limited to the above-described configuration, and an appropriate material that can set the wavelength of light emitted from the light emitting layer 2 to R (red), G (green), and B (blue) is used. It is possible to adopt any configuration. In addition, when used in a full color display application, full color display is possible by separately applying three types of light emitting materials corresponding to R, G, and B, or by overlaying a color filter on white light.

Moreover, as a material of the first substrate 1A and the second substrate 1B sandwiching the light emitting structure 100, for example, various glass materials can be used. In addition, a plastic material such as PMMA, polycarbonate, polystyrene, or a metal material such as aluminum can be used, and various other materials can be used. A particularly preferred material for the first substrate 1A and the second substrate 1B is a cycloolefin-based polymer, which has processability and material properties such as heat resistance, water resistance, and optical translucency. Everything is excellent.
Further, the first substrate 1A is a highly translucent material capable of making the total light transmittance 50% or more so that light emitted from the light emitting structure 100 (light emitting layer 2) can be transmitted as much as possible. It is preferable to form by.

  The light extraction sheet 7 is installed on the bonding surface with the first substrate 1 </ b> A via the adhesive layer 6. Examples of the adhesive / adhesive constituting the adhesive layer 6 include acrylic, urethane, rubber, and silicone adhesives. In any case, since it is used adjacent to the light emitting structure 100 of the light source that becomes high temperature, it is desirable that the storage elastic modulus G ′ is 1.0E + 04 (Pa) or more at 100 ° C. If the value is lower than this, there is a possibility that the light extraction sheet 7 and the first substrate 1A are displaced during use. If the light extraction sheet 7 and the first substrate 1 </ b> A are greatly deviated, light from the light emitting layer 2 is not efficiently incident on the light extraction sheet 7, so that the light use efficiency decreases.

  In order to stably secure a gap between the light emitting layer 2 and the light extraction sheet 7, transparent fine particles such as beads may be mixed in the contact / adhesive layer constituting the adhesive layer 6. As a result, the thickness of the adhesive layer 6 can be made uniform without adversely affecting the optical characteristics. The adhesive may be a double-sided tape or a single layer.

  The light extraction sheet 7 has a function of deflecting light from the light emitting layer 2 and emitting it in the irradiation direction F to improve the external extraction efficiency of light. The light extraction sheet 7 has a light deflection element 5 in which a large number of fine curved portions 5a having a convex curved surface in section are arranged without gaps on the light emission surface facing the base 8 opposite to the first substrate 1A. Is forming.

  In the illumination device 10 according to the present embodiment, the light B0 emitted from the light emitting layer 2 passes through the first substrate 1A as the light B1 and enters the light deflection element 5 of the light extraction sheet 7. As shown in FIG. 1, the light B1 incident on the light deflection element 5 is bent toward the irradiation direction F by a plurality of convex curved portions 5a arranged in the light deflection element 5, and the light B1 B2 is ejected from the exit surface to the outside.

Here, suppose that the light extraction sheet 7 including the light deflection element 5 is not provided in the illumination device 10 ′ as shown in FIG. 2, and the flat surface 1a of the first substrate 1A is the light emission surface. Most of the light B1 becomes light B12 that is reflected by the flat surface 1a and incident on the light emitting layer 2 again. Since the light B12 is not deflected in the irradiation direction F, it becomes lost light. For this reason, in order to improve the light extraction efficiency of the EL element 101, it is important to reduce the reflected light B12 and increase the light B2.
Further, the light B0 emitted from the light emitting layer 2 in the EL element 101 changes in chromaticity depending on the emission angle. In the illuminating device 10 shown in FIG. 1, by providing the light deflecting element 5 on the light emitting surface side of the EL element 101, the light B0 emitted from the light emitting layer 2 is deflected by the light deflecting element 5 and irradiated as the emitted light B2. Injected in direction F. At this time, it is possible to change the emission direction of the emitted light B2 by forming the convex portions 5a of the light deflection element 5 in different shapes according to the emission positions of the light B2 emitted from the light emitting layer 2. This makes it possible to suppress changes in chromaticity due to the emission angle.

By the way, as a conventional method for improving the external light extraction efficiency and the color difference of the EL element 101, a method of arranging a structure such as a prism sheet on the exit surface, or applying a filler on a transparent substrate to form an uneven surface. There are a method of installing the formed diffusion film, a method of arranging substantially hemispherical microlenses, and the like.
(A) However, the method of installing a structure part such as a prism sheet has the following problems.
Since the prism in the prism sheet or the like has a structure in which the planar shape occupies most, the inclination angle is constant due to the planar shape of the prism, and thus light at a specific angle can be efficiently extracted to the outside.
However, the light outside the above-mentioned specific angle has a low external extraction efficiency, and overall, there is a problem that the external extraction efficiency is low. In addition, the change in chromaticity coordinates depending on the emission angle of the EL element 101 has a constant inclination angle in the case of a prism shape, so that incident light at a specific angle is deflected to emission light at a specific angle. There is a drawback that the improvement effect based on the change due to the angle is low.

(B) The method of installing a diffusion film in which an uneven surface is formed by applying a filler to a transparent substrate 8 has the following problems.
When a rough surface is formed by applying a filler to the base material 8, the shape of the rough surface is determined by the degree of protrusion of the filler, so that a highly accurate uneven surface cannot be formed. Therefore, there arises a problem that it is not possible to form an accurate shape for controlling light on the uneven surface. For example, when an approximately hemispherical convex portion is formed by raising the filler, the filler is not sufficiently raised and only a part of the substantially hemispherical shape is formed. That is, when the ratio between the height and the width of the substantially hemispherical shape is the aspect ratio (height / width), the aspect ratio becomes small, resulting in a problem that the external extraction efficiency of light becomes small.

(C) The method of forming a microlens has the following problems.
The microlens can be molded with higher accuracy than the above-described diffusion filler, and can be formed into a substantially hemispherical shape with an increased aspect ratio. However, since the light from the light emitting layer 2 of the EL element 101 is isotropic, a substantially hemispherical shape is preferable for controlling the light emission direction, but when a substantially hemispherical microlens is arranged. In other words, the entire surface cannot be filled without a gap, and a flat surface gap is generated between the microlenses. When the gap between the flat surfaces is generated, the reflected light B12 is generated on the flat surface 1a shown in FIG. 2, and the reflected light B12 is not emitted in the irradiation direction F, so that the light use efficiency is lowered.

Further, it is possible to fill the entire flat surface 1a of the first substrate 1A with a close-packed structure sheet such as a hexagonal arrangement. However, when creating such a shape, a higher-precision molding process is required. Problems such as lens overlap are likely to occur. In addition, if the microlenses are array-molded with a small gap, a slight gap gap between the microlenses appears as macro unevenness, which is not preferable.
Therefore, even in this case, the substantial occupation area ratio is around 76%. As a result, a flat surface remains about 24%, which causes a problem that the efficiency of external extraction of light becomes insufficient.

Therefore, in the illuminating device 10 according to the present embodiment, in order to improve the light extraction efficiency of the EL element 101 and the change in chromaticity depending on the emission angle, the cross-sectional shape of the convex curved portion 5a is an irregular function shown in FIG. A light extraction sheet 7 provided on the exit surface with the light deflection element 5 in which a large number of convex curved surfaces represented by f (x) are arranged is provided on the surface of the EL element 101.
The light extraction sheet | seat 7 by this embodiment is demonstrated in detail using FIG.1 and FIG.3. The light deflecting element 5 is formed by arranging a large number of convex portions 5a without gaps on one surface of the light-transmitting substrate 8, that is, the surface 8a that is the surface in the irradiation direction F. Yes. The cross-sectional shape of a large number of convex curved portions 5a in the light deflection element 5 is formed as a concavo-convex structure composed of a large number of convex curved surfaces represented by an irregular function f (x) as shown in FIG.

In FIG. 3, in the light deflection element 5, the displacement along the light exit surface of the substrate 8 is represented by x, and the cross-sectional height shape of a large number of convex curved portions 5a is represented as an irregular function f (x). It is a graph which shows the cross-sectional shape of the optical deflection | deviation element 5, when the function which extracted the inflection points g1, g2, g3, ... in (x) is made into g (x).
Here, the function g (x) indicates an inflection point of the function f (x). That is, the second derivative f ″ (x) = 0 on the convex curve in the function f (x), and the sign of the second derivative f ″ (x) changes before and after the inflection point. Therefore, in FIG. 3, in order to show the change of the light quantity and the color difference when the average gradient ratio | dg (x) / dx | _Ave of the absolute value of the gradient between two adjacent points of the function f (x) is changed. A function g (x) is represented by connecting inflection points g1, g2, g3,.

Here, in the function f (x) of the cross-sectional height shape by a large number of convex portions 5a, the maximum value is f (x) max, the minimum value is f (x) min, and the difference Δf between the maximum value and the minimum value. It is assumed that (x) = f (x) max−f (x) min satisfies the following expression (1).
0.001 mm ≦ Δf (x) ≦ 0.300 mm (1)
That is, the difference Δf (x) between the maximum value and the minimum value is preferably 0.001 mm or more and 0.300 mm or less.
If the value of Δf (x) is less than 0.001 mm, the emitted light has a wavelength in the visible light region, which is not preferable because the light deflection action by the light extraction sheet 7 is dependent on the wavelength. Further, if the value of Δf (x) is larger than 0.300 mm, the surface irregularity shape of the light deflection element 5 is easily visually recognized, which is not preferable.
Further, even within the range of the above formula (1), if the value of Δf (x) is too small, the uneven surface of the light extraction sheet 7 is likely to be damaged, and the value of Δf (x) is not preferable. If it is too large, it will be difficult to produce a mold and formability of the light extraction sheet 7, and it is desirable that the range is preferably 0.010 mm ≦ Δf (x) ≦ 0.100 mm.

In addition, regarding the illumination device 10 according to the present embodiment, in the function g (x) obtained by extracting the inflection point in the function f (x), the average inclination rate of the absolute value of the inclination between two adjacent points is | dg (x) / as _Ave, average ramp rate _{| | dx dg (x) /} dx | figure relative light amount and the relative color differences when changing the value of _Ave 4 (a), shown in (b). The average inclination rate | dg (x) / dx | _Ave has a characteristic that the value becomes larger when the slope of the convex section of the section is steeper with respect to the displacement x, and the optical characteristics of the light quantity and the color difference are improved.
In FIG. 4 (a), the horizontal axis represents the average gradient | dg (x) / dx | _Ave , and the vertical axis represents the relative value when the average gradient | dg (x) / dx | _Ave is changed. The amount of light. Here, the relative light amount is a value when the integrated light amount of light when the light extraction sheet 7 is not used for the EL element 101 is 1.00.

In FIG. 4B, the horizontal axis represents the average gradient | dg (x) / dx | _Ave , and the vertical axis represents the relative color difference when the average gradient | dg (x) / dx | _Ave is changed. The relative color difference means that the maximum change ΔEu′v ′ of the chromaticity coordinates u ′ and v ′ in the range of 0 to 80 degrees in the measurement visual field when the light extraction sheet 7 is not used for the EL element 101 is 1.00. Is the relative color difference.
Here, chromaticity coordinates u ′ and v ′ are CIE (International Commission on Illumination) 1976U. C. S is a numerical value indicating a color defined by S, and ΔEu′v ′ calculated using chromaticity coordinates u ′ and v ′ is the maximum value and the minimum value of u ′ in the range of 0 to 80 degrees in the measurement visual field. It is a numerical value obtained by taking the square root of the sum of the squares of the difference (u′max−u′min) and the difference between the maximum value and the minimum value of v ′ (v′max−v′min). In addition,
ΔEu′v ′ = √ {(umax−umin) ² + (vmax−vmin) ² }
That is, it is the maximum amount of change in chromaticity u ′, v ′ within the range of 0 to 80 degrees of the measurement visual field.

In FIG. 4A, the relative light amount increases as the average gradient | dg (x) / dx | _Ave increases.
This is because, among the light emitted from the EL element 101, the larger the emission angle, the greater the amount of light that is totally reflected at the exit surface interface (surface 1a) and returned to the inside of the EL element 101. The light extraction efficiency decreases. On the other hand, by providing the light extraction sheet 7 provided with the light deflection element 5 on the light emission surface of the EL element 101, the emission light having a large emission angle that has been totally reflected at the emission surface interface (emitted from the EL element 101). This is because the external extraction efficiency of light is improved because the light is deflected and emitted toward the observation surface side (injection direction F).

In FIG. 4B, as the average gradient | dg (x) / dx | _Ave increases, the effect of deflecting and diffusing the emitted light emitted from the EL element 101 in the front direction is increased. Therefore, the relative color difference is improved. When the average gradient | dg (x) / dx | _Ave is greater than 1, the relative color difference is improved by 10% or more, and when it is further increased, the relative color difference is gradually improved. When the average gradient | dg (x) / dx | _Ave is 8 or more, the effect of improving the color difference becomes substantially constant and the relative color difference converges to a constant value.
For the above reasons, the value of the average gradient | dg (x) / dx | _Ave is preferably in the range of 1 ≦ | dg (x) / dx | _Ave ≦ 8. Since the reduction rate of the relative color difference is preferably larger, more preferably, the reduction rate is 50% or more with respect to the maximum value (about 1.4) of the relative color difference. 2 ≦ | dg (x) / dx | _Ave ≦ It is desirable to be within the range of 8. More preferably, since the moldability becomes difficult when the average gradient | dg (x) / dx | _Ave increases, the effect of improving the color difference hardly changes. 2 ≦ | dg (x) / dx | _Ave ≦ It is preferable to be within the range of 4.

Here, as a material for molding the light extraction sheet 7, a material having light transmittance with respect to the wavelength of light emitted from the light emitting layer 2 is used, for example, a plastic material usable for an optical member is used. be able to.
Examples of this plastic material include polyester resin, acrylic resin, polycarbonate resin, polystyrene resin, MS (acrylic and styrene copolymer) resin, polymethylpentene resin, thermoplastic resin such as cycloolefin polymer, or polyester acrylate. And transparent resins such as radiation curable resins composed of oligomers such as urethane acrylate and epoxy acrylate, or acrylates.

The light extraction sheet 7 may be used with fine particles dispersed in a transparent resin depending on the application. By dispersing the fine particles in the transparent resin, when the light incident on the light extraction sheet 7 is emitted in the irradiation direction F, the diffusivity is further increased, so that it is possible to improve the change of the chromaticity depending on the viewing angle. In addition, when used as the illumination device 10, there is an advantage that defects are hardly observed.
As the fine particles, particles made of an inorganic oxide or particles made of a resin can be used. For example, transparent particles made of an inorganic oxide include particles made of silica, alumina, titanium oxide, or the like. The transparent particles made of resin include acrylic particles, styrene particles, styrene acrylic particles and cross-linked products thereof, melamine-formalin condensate particles, PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxy resin), FEP (tetrafluoroethylene). Examples thereof include fluorine-containing polymer particles such as fluoroethylene monohexafluoropropylene copolymer), PVDF (polyfluorovinylidene), and ETFE (ethylene monotetrafluoroethylene copolymer), and silicone resin particles. These fine particles may be used as a mixture of two or more.

And the light extraction sheet | seat 7 is manufactured by the method of shape | molding by apply | coating the material mentioned above on a base material, or by shape | molding by pouring into a metal mold | die and solidifying.
There is the following method as a method for producing a mold of the light deflection element 5 having an uneven shape in which convex curved portions 5a corresponding to the function f (x) of the cross-sectional height shape are arranged. That is, a cutting tool having various lens shapes is used for a mold for forming the light deflecting element 5, and the cutting amount of the cutting tool is determined for each convex curved portion 5a using a random number program. A method of cutting to a depth, a method of forming a concavo-convex shape of the convex portion 5a by etching the mold surface, a method of processing the mold surface into a concavo-convex shape with a random number program by a laser, alumina, etc. For example, a method of changing the particle diameter or discharge pressure of the fine particles into a concavo-convex shape by sandblasting can be used.

By such a processing method, it is possible to form the light deflection element 5 having a large number of randomly curved portions 5a that are represented by an irregular function f (x). In addition, the shape of the convex curved surface which is a longitudinal section of the convex curved surface 5a in the light deflection element 5 may be a bent shape consisting of a polygonal line as shown in FIGS. 1 and 3, or may be a curved surface shape, including any shape. Shall be.
In addition to the method of producing the light extraction sheet 7 in which the light deflection element 5 is formed using such a mold, a mold formed with a thermoplastic resin or an ultraviolet curable resin and the above shape is used. It can be molded by extrusion molding, injection molding, UV molding, or the like. At that time, a diffusing agent such as a filler can be dispersed inside and molded.

  Moreover, when manufacturing the light extraction sheet | seat 7, you may disperse | distribute ultrafine particles, such as an antimony containing tin oxide (henceforth ATO) and tin containing indium oxide (ITO) of electroconductive fine particles, as an antistatic agent. By dispersing the antistatic agent, the antifouling property of the light extraction sheet 7 can be improved.

  In the manufacturing method of the light extraction sheet 7, when the light deflection element 5 and the substrate 8 are molded separately as in the UV molding method, the sheet-like substrate 8 is a transparent film, for example, cellulose triacetate, A stretched or unstretched film of a thermoplastic resin such as polyester, polyamide, polyimide, polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, methyl polymethacrylate, polycarbonate, or polyurethane can be used. Although the thickness of the base material 8 depends on the rigidity of the base material 8, a thickness of 50 to 300 μm is preferable from the viewpoint of handling such as workability.

When the adhesive force between the light deflecting element 5 and the substrate 8 is not strong, or when the adhesive force decreases due to external influences such as cold, moisture absorption and desorption, the light deflecting element 5 and the substrate 8 Between them, a primer layer having high adhesion to both materials may be provided, or the action of the primer layer may be added to the light deflection element 5. Alternatively, an easy adhesion process such as a corona discharge process may be performed.
In the above description, a typical example of the light extraction sheet 7 has been described. However, if the illumination device 10 according to the present embodiment can achieve the optical characteristics by the light extraction sheet 7, materials other than the above are used. It is also possible to manufacture using a structure, a process, or the like.

  As described above, according to the illuminating device 10 including the light extraction sheet 7 and the EL element 101 according to the present embodiment, the light extraction in which the light deflection element 5 in which a large number of fine convex portions 5a are arranged without gaps is formed. By providing the sheet 7, assuming that the displacement in the width direction of the light deflection element 5 is x and the height shape of the convex curved portion 5 a at the displacement x is indicated by a function f (x), the height shape function f (x ) Is expressed by an irregular function, the exit surface of the light deflecting element 5 can be formed by the irregularly curved convex portion 5a, and the external extraction efficiency of light and the chromaticity depending on the exit angle. The change in the coordinates can be improved, and the lighting device 10 with high light use efficiency can be obtained.

Moreover, according to the illumination device 10 of the present embodiment, Δf (x) = f (x) _max −f (x) _min is satisfied, and the light deflection action by the light deflection element 5 is achieved by satisfying the above expression (1). There is an advantage that wavelength dependency does not occur and a suitable injection characteristic can be exhibited, and the uneven shapes of a large number of convex portions 5a are not visually confirmed.
In addition, in g (x), a function obtained by extracting the inflection point in the function f (x), the absolute value | dg (x) / dx | _Ave of the average gradient of the gradient between two adjacent points is expressed by the above equation (2). Therefore, as the absolute value | dg (x) / dx | _Ave increases, the relative light quantity increases and the relative color difference gradually decreases as compared with the case where the light extraction sheet 7 is not laminated on the EL element 101. And have the advantage of improving.

  Furthermore, by using the illumination device 10 according to the present embodiment as a light source, a liquid crystal display device including a liquid crystal image display element and a display device including an image display element can be configured to obtain the above-described optical characteristics. In addition, a liquid crystal display device or a display device having high light utilization efficiency and design properties can be obtained.

It should be noted that the present invention is not limited to the above-described embodiment, and appropriate changes and substitutions can be made without departing from the gist of the present invention.
In the above-described embodiment, a typical example of the light extraction sheet 7 has been described. However, if the optical characteristics of the present embodiment can be achieved, the light extraction is performed using materials, structures, processes, and the like other than those described above. It is also possible to produce the sheet 7.

Hereinafter, the illuminating device 10 by the Example of this invention is demonstrated in detail below. In addition, this invention is not limited only to these Examples.
(Comparative example)
As illustrated in FIG. 2, the illumination device 10 ′ according to the comparative example 1 has a configuration in which the light extraction sheet 7 is not provided on the light emission side surface of the EL element 101 according to the above-described embodiment.

(Example)
As an example of the present invention, an illuminating device 10 in which the light extraction sheet 7 was bonded to the flat surface 1a that is the emission surface of the first substrate 1A in the EL element 101 described above was used.
A method for producing the light extraction sheet 7 is as follows. First, a transparent PET film having a thickness of 188 μm was used as the substrate 8, and an ultraviolet curable acrylic resin having a refractive index of 1.50 was applied thereon. Then, this ultraviolet curable acrylic resin is press-molded by a cylinder mold patterned in the shape of the light deflection element 5 in which a large number of convex portions 5a defined by an irregular function f (x) are arranged, While transporting the transparent PET film coated with the curable acrylic resin, UV light was irradiated from the transparent PET film side for exposure.
As a result, the ultraviolet curable acrylic resin was cured into a shape in which a large number of convex curved portions 5a defined by an irregular function f (x) were arranged without gaps, and the light deflection element 5 was molded on the substrate 8. . After curing the acrylic resin, the light extraction sheet 7 was prepared by peeling the cylinder mold from the transparent PET film.
The base material 8 of the obtained light extraction sheet 7 was bonded to the EL element 101 described above via the adhesive layer 6 made of an adhesive, thereby obtaining a sample of the lighting device 10 according to the test example.

The illuminating device 10 according to the test example has an absolute value of an inclination between two adjacent points in a function g (x) obtained by extracting an inflection point in the function f (x) with respect to a large number of the curved portions 5a of the light deflection element 5. As shown in Table 1 below, the average gradient | dg (x) / dx | _Ave is set to 0.5, 1.0, 2.0, and 8.0, respectively. 2, Test Example 3 and Test Example 4.
About the illuminating device 10 by the comparative example 1 and each test example 1-4, the predetermined voltage was applied to the light emission structure 100, and the integrated light quantity and chromaticity were measured. The results are shown in Table 1. Here, the relative light quantity and the relative color difference are values when the integrated light quantity and chromaticity values in Comparative Example 1 are set to 1.00.

From Table 1, when the average gradient | dg (x) / dx | _Ave is 0.5, the relative light amount is higher than that of Comparative Example 1, but the relative color difference is increased and deteriorated, which is not preferable. On the other hand, when the average gradient | dg (x) / dx | _Ave is set to a large value of 1.0 or more, the relative light amount increases and the relative color difference is reduced and converged compared to the first comparative example. It is clear that it has improved. Test examples 2, 3, and 4 correspond to examples.
Although it is possible to obtain good optical characteristics even when the value of | dg (x) / dx | _Ave is 8 or more, since the shape of the convex curve portion 5a becomes steeper, it can be manufactured by molding. It becomes difficult. For this reason, the upper limit is set to 8 here. Therefore, it has been confirmed that the above (2) is preferably satisfied.

DESCRIPTION OF SYMBOLS 1A, 1B Substrate 2 Light emitting layer 3 Anode 4 Cathode 5a Convex part 5 Light deflection element 6 Adhesive layer 7 Light extraction sheet 8 Base material 100 ... Light emitting structure 101 ... EL elements B0, B1, B2, B12 Light

Claims (7)

A light extraction member including a light emitting unit and a light deflection element that guides and emits the light emitted from the light emitting unit;
The light deflection element is formed by arranging a large number of fine convex portions without any gaps on the light exit surface,
The convex curved portion is formed as a convex curved surface in a longitudinal sectional view, the displacement in the width direction of a large number of the convex curved surfaces is x, and the height shape of the convex curved surface is f (x),
F (x) is represented by an irregular function,
In the function f (x) of the height shape of the convex curved surface in the longitudinal sectional view of the light deflection element,
When the maximum value is f (x) _max and the minimum value is f (x) _min ,
Δf (x) = f (x) _max −f (x) _min
The Δf (x) satisfies the following formula (1),
When g (x) is a function obtained by extracting an inflection point in the function f (x) of the height shape of the convex curved surface,
In the function g (x), the absolute value | dg (x) / dx | _Ave of the average gradient of the gradient between two adjacent inflection points satisfies the following equation (2):
When the average gradient | dg (x) / dx | _Ave is changed, the maximum change in the chromaticity coordinates u ′ and v ′ in the range of 0 to 80 degrees in the measurement visual field when the light extraction member is not used Illumination characterized in that the reduction rate with respect to the maximum value of the relative color difference when the amount ΔEu′v ′ = √ {(umax−umin) ² + (vmax−vmin) ² } is 1.00 is 50% or more. apparatus.
0.001 mm ≦ Δf (x) ≦ 0.300 mm (1)
2 ≦ | dg (x) / dx | _Ave ≦ 8 (2)   The lighting device according to claim 1, wherein the light deflection element is formed by arranging a large number of convex curved portions at random.   The lighting device according to claim 1, wherein the light emitting means is an EL element. It is a manufacturing method of the illuminating device according to any one of claims 1 to 3,
The method of manufacturing a lighting device, wherein the light extraction member is molded by solidifying a material with a mold.   5. The method of manufacturing an illuminating device according to claim 4, wherein the mold is formed by randomly arranging convex curved portions using cutting, laser processing, or sand plasting. A lighting device according to any one of claims 1 to 3;
A liquid crystal display device comprising: a liquid crystal image display element disposed on a light emission surface side of the illumination device. A lighting device according to any one of claims 1 to 3;
Display apparatus comprising the an image display element disposed on the exit surface side of the light of the lighting device.

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