Diffusion member, laminate, diffusion member set, LED backlight and display device

Abstract

SOLUTION: There is provided a lamination member which has an LED baseboard having a support baseboard and LED element arranged at one face side of the support baseboard, a sealing material sheet arranged between the LED baseboard of an LED backlight having a diffusion member and the diffusion member, and used for sealing the LED element, and a first layer arranged at one face side of the sealing material sheet, and having light permeability and light diffusibility, and in which the first layer is arranged in a pattern shape at one face side of the sealing material sheet, and the sealing material sheet is constituted of a sealing material composition containing an olefin resin.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a set of a diffusing member, a laminate, and a diffusing member used in, for example, a direct-type LED backlight, and to an LED backlight and a display device using the same. [Background technology]

[0002] 2. Description of the Related Art In recent years, display devices using LED backlights as light sources, such as liquid crystal display devices, have rapidly become widespread.

[0003] Here, LED backlights are broadly divided into direct-light type and edge-light type. In small and medium-sized display devices such as mobile terminals such as smartphones, edge-light type LED backlights are usually used, but from the standpoint of brightness, the use of direct-light type LED backlights is being considered. On the other hand, in large display devices such as large-screen LCD TVs, direct-light type LED backlights are often used.

[0004] Direct-type LED backlights have a structure in which multiple LED elements are arranged on a substrate. In such direct-type LED backlights, by independently controlling multiple LED elements, it is possible to achieve so-called local dimming, which adjusts the brightness of each area of ​​the LED backlight according to the brightness and darkness of the displayed image. This makes it possible to significantly improve the contrast of the display device and reduce power consumption.

[0005] In direct-type LED backlights, a diffusion plate is placed above the LED elements to prevent uneven brightness. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2018-67441 A [Patent Document 2] JP 2017-92021 A [Patent Document 3] Patent No. 5062408 [Patent Document 4] JP 2019-61954 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, in a direct-type LED backlight, the LED elements and the diffusion plate must be spaced apart to suppress uneven brightness. This makes it difficult to make the backlight thin. In particular, when the number of LED elements is reduced to reduce costs and power consumption, the spacing between the LED elements increases, making uneven brightness more likely to occur. In this case, the distance between the LED elements and the diffusion plate must be increased, making it more difficult to make the backlight thin. Therefore, in a conventional direct-type LED backlight, there is a problem in that it is difficult to simultaneously achieve uniform brightness and a thin backlight.

[0008] Also, in order to improve the in-plane uniformity of brightness, it has been proposed to further place a transmissive reflector between the LED element and the diffusion plate (see, for example, Patent Document 1). The transmissive reflector has a pattern of reflective and transmissive parts, and more specifically, has a pattern in which the reflective part is directly above the LED element, and the transmissive part gradually becomes larger from directly above the LED element toward the periphery. This allows the light directly above the LED element to be reflected and diffused to the periphery, and emitted from the transmissive part around it, improving the in-plane uniformity of brightness.

[0009] However, even when such a transflector is used, it is difficult to make the device thinner because it is necessary to place the LED element and the transflector apart in order to suppress uneven brightness. In addition, the transflector has a patterned reflective portion and a transmissive portion, and since the reflective portion is placed directly above the LED element, it is necessary to align the LED element with the transflector.

[0010] Furthermore, in order to achieve uniform brightness and a thinner design, for example, Patent Document 2 proposes placing a half mirror between the LED element and the diffusion plate, which reflects part of the incident light and transmits part of it, and using a half mirror whose reflectance is lower for oblique incidence than for perpendicular incidence.

[0011] Furthermore, in order to make the brightness uniform, for example, Patent Document 3 proposes placing a diffractive optical element for a backlight between the LED element and the diffuser plate. The diffractive optical element transmits and diffracts light from the light source, and emits transmitted diffracted light with a ring-shaped intensity distribution in which the intensity of the transmitted diffracted light emitted to the periphery is stronger than the intensity of the transmitted diffracted light emitted toward the center of the optical axis, the intensity being greater than 0.

[0012] The present disclosure has been made in consideration of the above-mentioned situation, and has as its main object to provide a diffusion member, a laminate, a diffusion member set, an LED backlight, and a display device that are capable of achieving a thin structure while improving the in-plane uniformity of brightness. [Means for solving the problem]

[0013] As a result of intensive research to solve the above problems, the inventors discovered that by using, as a diffusion member, a layer having optical transparency and optical diffusion properties in combination with a layer having incident angle-dependent reflectance and transmittance, it is possible to improve the in-plane uniformity of brightness while achieving a thinner display, and thus completed the present invention.

[0014] That is, one embodiment of the present disclosure provides a diffusing member having a first layer and a second layer in this order, wherein the first layer has light transparency and light diffusivity, and the second layer has a reflectance that increases as the absolute value of the incident angle of light with respect to the surface of the second layer facing the first layer decreases, and a transmittance that increases as the absolute value of the incident angle of light with respect to the surface of the second layer facing the first layer increases.

[0015] Another embodiment of the present disclosure provides a diffusing member having a transmission type diffraction grating or a microlens array and a dielectric multilayer film.

[0016] Another embodiment of the present disclosure provides a laminate comprising the above-mentioned diffusion member and an encapsulant sheet disposed on the first layer side of the diffusion member and used to encapsulate an LED element, the encapsulant sheet being made of an encapsulant composition containing a thermoplastic resin.

[0017] Another embodiment of the present disclosure provides a laminate comprising the above-mentioned diffusing member and an encapsulant sheet disposed on a side of the diffusing member facing a transmission diffraction grating or a microlens array and used to encapsulate an LED element, the encapsulant sheet being composed of an encapsulant composition containing a thermoplastic resin.

[0018] Another embodiment of the present disclosure provides a set of diffusion members comprising: a first member having a first layer and a sealant sheet used to seal an LED element; and a second member having a second layer and arranged on a surface of the first member facing the first layer with a gap therebetween, wherein the first layer has light transparency and light diffusion properties, the second layer has a reflectance that increases as the absolute value of the incident angle of light with respect to the surface of the second layer facing the first layer decreases and a transmittance that increases as the absolute value of the incident angle of light with respect to the surface of the second layer facing the first layer increases, and the sealant sheet is composed of a sealant composition containing a thermoplastic resin.

[0019] Another embodiment of the present disclosure provides an LED backlight comprising: an LED substrate having a plurality of LED elements arranged on one side of a support substrate; and a diffusing member arranged on the LED substrate side facing the LED elements, the diffusing member having a first layer and a second layer in that order from the LED substrate side, the first layer being optically transparent and optically diffusive, the second layer having an increasing reflectance as the absolute value of the angle of incidence of light with respect to the surface of the second layer facing the first layer becomes smaller, and an increasing transmittance as the absolute value of the angle of incidence of light with respect to the surface of the second layer facing the first layer becomes larger.

[0020] Another embodiment of the present disclosure provides an LED backlight comprising an LED substrate having a plurality of LED elements arranged on one side of a support substrate, and a diffusing member arranged on the side of the LED substrate facing the LED elements, the diffusing member having, in order from the LED substrate side, a transmissive diffraction grating or a microlens array, and a dielectric multilayer film.

[0021] The present disclosure provides a display device including a display panel and the above-mentioned LED backlight disposed on a rear surface of the display panel. Effect of the Invention

[0022] The present disclosure has an effect of providing a diffusion member, an LED backlight, and a display device that can be made thinner while improving the in-plane uniformity of luminance. [Brief description of the drawings]

[0023] [Figure 1] 1 is a schematic cross-sectional view illustrating a diffusion member of the present disclosure. [Diagram 2] 1 is a schematic cross-sectional view illustrating an LED backlight of the present disclosure. [Diagram 3] FIG. 1 is a diagram illustrating a diffusion angle. [Figure 4] FIG. 2 is a diagram illustrating light diffusivity in the present disclosure. [Diagram 5] FIG. 2 is a diagram illustrating light diffusivity in the present disclosure. [Figure 6] 1 is a schematic cross-sectional view illustrating a transmission type diffraction grating according to the present disclosure. [Figure 7] 1 is a schematic cross-sectional view illustrating a diffusion member according to the present disclosure. [Figure 8] 1A and 1B are schematic plan and cross-sectional views illustrating a reflecting structure in the present disclosure. [Figure 9] 1A and 1B are schematic plan and cross-sectional views illustrating a reflecting structure in the present disclosure. [Figure 10] 1 is a schematic cross-sectional view illustrating a reflecting structure according to the present disclosure. [Figure 11]1 is a schematic cross-sectional view illustrating a diffusion member of the present disclosure. [Figure 12] 1 is a schematic cross-sectional view illustrating a laminate according to the present disclosure. [Figure 13] 1A to 1C are process diagrams illustrating a manufacturing method for an LED backlight according to the present disclosure. [Figure 14] 1A to 1C are process diagrams illustrating a manufacturing method for an LED backlight according to the present disclosure. [Figure 15] 1 is a schematic cross-sectional view illustrating a laminate according to the present disclosure. [Figure 16] 1 is a schematic cross-sectional view illustrating a laminate according to the present disclosure. [Figure 17] 1 is a schematic cross-sectional view illustrating a laminate according to the present disclosure. [Figure 18] 1 is a schematic cross-sectional view illustrating a set of diffusion members in the present disclosure. [Figure 19] 1 is a schematic cross-sectional view illustrating an LED backlight of the present disclosure. [Figure 20] 1 is a schematic cross-sectional view illustrating an LED backlight of the present disclosure. [Figure 21] 1 is a schematic cross-sectional view illustrating an LED backlight of the present disclosure. [Figure 22] 1 is a schematic cross-sectional view illustrating an LED backlight of the present disclosure. [Diagram 23] 1 is a schematic diagram illustrating a display device according to the present disclosure. [Figure 24] 1 is a schematic diagram illustrating a display device according to the present disclosure. [Diagram 25] 13 is a graph showing the incidence angle dependence of the reflectance and transmittance of the second layer of the diffusing member of Test Example 1. [Figure 26] 1 shows optical simulation results of Test Example 1. [Figure 27] 13 shows optical simulation results of Test Example 2. [Figure 28] 13 is a graph showing the relationship between the position of a through hole in a transmission reflector and the aperture ratio in Test Example 3. [Figure 29] 13 shows the results of an optical simulation of Test Example 3. [Diagram 30]13 shows the results of an optical simulation of Test Example 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The diffusion member, LED backlight, and display device of the present disclosure will be described below. However, the present disclosure can be implemented in many different embodiments, and is not to be interpreted as being limited to the description of the embodiments exemplified below. In addition, in order to make the explanation clearer, the drawings may be schematic in terms of the width, thickness, shape, etc. of each member compared to the embodiments, but these are merely examples and do not limit the interpretation of the present disclosure. In addition, in this specification and each figure, elements similar to those described above with respect to the previously mentioned figures may be given the same reference numerals, and detailed explanations may be omitted as appropriate.

[0025] In this specification, when expressing an aspect in which another component is disposed above or below a certain component, the term "on the face side" is used, unless otherwise specified, to include both a case in which another component is disposed directly above or below a certain component so as to be in contact with the certain component, and a case in which another component is disposed above or below a certain component with another component in between.

[0026] In addition, in this specification, "LED" means light-emitting diode. In addition, in this specification, the terms "sheet," "film," "plate," and the like are not distinguished from one another solely on the basis of differences in name. For example, the term "sheet" is used to include members also known as films and plates.

[0027] A. Diffusion material The diffusion member in the present disclosure has two embodiments, each of which will be described below.

[0028] I. First embodiment of the diffusion member A first embodiment of the diffusing member of the present disclosure is a member having a first layer and a second layer in this order, the first layer having light transmittance and light diffusibility, the second layer having a reflectance that increases as the absolute value of the incident angle of light to the surface of the second layer on the first layer side decreases, and a transmittance that increases as the absolute value of the incident angle of light to the surface of the second layer on the first layer side increases. When using the diffusing member of the present disclosure, the surface on the first layer side is used as the light incident surface.

[0029] Hereinafter, a first embodiment of the diffusing member of the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an example of the first embodiment of the diffusing member of the present disclosure. As illustrated in FIG. 1, the diffusing member 1 has a first layer 2 and a second layer 3 in this order. The first layer 2 has light transmissivity and light diffusivity, and transmits and diffuses light L1 and L2 incident from a surface 2A of the first layer 2 opposite to the surface of the first layer 3. In addition, the reflectance of the second layer 3 increases as the absolute value of the incident angle of light to the surface 3A of the second layer 3 on the first layer 2 side decreases, and the transmittance increases as the absolute value of the incident angle of light to the surface 3A of the second layer 3 on the first layer 2 side increases. Therefore, the second layer 3 can reflect light L1 incident at a low incident angle θ1 to the surface 3A of the second layer 3 on the first layer 2 side, and transmit light L2 incident at a high incident angle θ2 to the surface 3A of the second layer 3 on the first layer 2 side. The low incidence angle refers to an incidence angle whose absolute value is small, and the high incidence angle refers to an incidence angle whose absolute value is large.

[0030] Fig. 2 is a schematic cross-sectional view showing an example of a direct-illumination type LED backlight including a diffusing member according to the first embodiment of the present disclosure, and is an example including the diffusing member shown in Fig. 1. As illustrated in Fig. 2, the LED backlight 10 has an LED substrate 11 having LED elements 13 arranged on one surface of a support substrate 12, and a diffusing member 1 arranged on the surface of the LED substrate 11 facing the LED elements 13. The diffusing member 1 is arranged such that a surface 1A on the first layer 2 side faces the LED substrate 11. In Fig. 2, the LED substrate 11 and the diffusing member 1 are arranged apart from each other.

[0031] In the present disclosure, as shown in FIG. 1, light incident from the surface 1A of the diffusing member 1 on the first layer 2 side is diffused by the first layer 2, and light L1 incident at a low incident angle θ1 on the surface 3A of the second layer 3 on the first layer 2 side of the light that has been diffused through the first layer 2 can be reflected by the surface 3A of the second layer 3 on the first layer 2 side and can be diffused by being incident again on the first layer 2, as shown in FIG. 2. Among the light that has been diffused through the first layer 2, light L2, L2' incident at a high incident angle θ2 on the surface 3A of the second layer 3 on the first layer 2 side of the light can be transmitted through the second layer 3 and emitted from the surface 1B of the diffusing member 1 on the second layer 3 side. In addition, by combining the first layer and the second layer, light incident from the surface of the first layer side of the diffusing member, particularly light incident at a low incident angle from the surface of the first layer side of the diffusing member, can be diffused by being transmitted through the first layer many times, and can be emitted from the surface of the second layer side of the diffusing member at a high emission angle. Therefore, when the diffusion member of the present disclosure is used in a direct-type LED backlight, the light emitted from the LED element can be diffused over the entire light-emitting surface, improving the in-plane uniformity of brightness.

[0032] In addition, in the present disclosure, as described above, by combining the first layer and the second layer, light incident at a low angle from the first layer surface of the diffusing member can be transmitted through the first layer many times, so that the optical path length from when the light enters the first layer surface of the diffusing member until when it exits from the second layer surface of the diffusing member can be lengthened. This allows a portion of the light emitted from the LED element and then exiting from the second layer surface of the diffusing member to be exited from a position away from the LED element in the in-plane direction, rather than directly above the LED element. Therefore, in the direct type LED backlight having the diffusion member of the present disclosure, even if the distance between the LED element and the diffusion member is shortened, the brightness unevenness can be suppressed. Therefore, it is possible to achieve a thin structure while improving the in-plane brightness uniformity. In addition, even if the number of LED elements is reduced, the brightness unevenness can be suppressed. Therefore, it is possible to simultaneously achieve uniform brightness, a thin structure, low costs, and low power consumption.

[0033] Furthermore, unlike conventional transflective plates, the diffusing member of the present disclosure does not require alignment with the LED elements, and therefore LED backlights can be easily manufactured using the diffusing member of the present disclosure.

[0034] A first embodiment of the diffusion member of the present disclosure will be described in detail below.

[0035] 1.First layer The first layer in the present disclosure is disposed on one surface side of a second layer described below, and is a member having optical transparency and optical diffusion properties.

[0036] The light transmittance of the first layer is, for example, preferably a total light transmittance of 50% or more, more preferably 70% or more, and particularly preferably 90% or more. When the total light transmittance of the first layer is in the above range, the luminance can be increased when the diffusing member of the present disclosure is used in an LED backlight.

[0037] The total light transmittance of the first layer can be measured, for example, by a method in accordance with JIS K7361-1: 1997. As the light source, CIE standard illuminant D65 can be used.

[0038] The light diffusion of the first layer may be, for example, a light diffusion that randomly diffuses light, or a light diffusion that mainly diffuses light in a specific direction. The light diffusion that mainly diffuses light in a specific direction is a property that deflects light, that is, a property that changes the traveling direction of light. Among them, the light diffusion of the first layer is preferably a light diffusion that mainly diffuses light in a specific direction. By deflecting light in a predetermined direction, that is, by controlling the traveling direction of light, it is possible to shape light into any shape or any intensity distribution, and the in-plane uniformity of brightness can be further improved.

[0039] When the light diffusion property of the first layer is a light diffusion property that randomly diffuses light, for example, the diffusion angle of light incident on the first layer can be 10° or more, 15° or more, or 20° or more. The diffusion angle of light incident on the first layer can be, for example, 85° or less, 60° or less, or 50° or less. When the diffusion angle is within the above range, the in-plane uniformity of luminance can be improved when the diffusion member of the present disclosure is used in an LED backlight.

[0040] Here, the diffusion angle will be described. Fig. 3 is a graph illustrating a transmitted light intensity distribution, and is a diagram illustrating the diffusion angle. In this specification, the maximum transmitted light intensity I of light emitted from the other surface of the first layer when light is perpendicularly incident on one surface of the first layer constituting the diffusion member is defined as max The difference between the two angles, which is half the full width at half maximum (FWHM), is defined as the diffusion angle α.

[0041] The diffusion angle can be measured using a goniophotometer or a goniospectrophotometer. For example, a goniophotometer (GP-200) manufactured by Murakami Color Research Laboratory can be used to measure the diffusion angle.

[0042] In addition, when the light diffusion property of the first layer is a light diffusion property that mainly diffuses light in a specific direction, the shape and intensity distribution of the light transmitted through the first layer are not particularly limited, and are appropriately selected according to the light distribution characteristics of the light source and the shape and intensity distribution of the target light. For example, the light diffusion property of the first layer can be a property of emitting light having a non-Gaussian intensity distribution, and specifically, a property of emitting light having an annular intensity distribution or a property of emitting light having a top-hat intensity distribution. Figures 4(a) and (b) are examples of an annular intensity distribution, and Figure 5 is an example of a top-hat intensity distribution.

[0043] Among them, the light diffusion property of the first layer is preferably a property of emitting light having an annular intensity distribution. In particular, the light diffusion property of the first layer is preferably a property of emitting light having an annular intensity distribution, and the intensity of the transmitted light emitted at the center of the optical axis is preferably almost zero, for example, as shown in FIG. 4(a). The light incident from the surface on the first layer side of the diffusing member is spread in an annular shape by the first layer, and the light incident at a low angle of incidence on the surface on the first layer side of the second layer is reflected by the surface on the first layer side of the second layer and then re-enters the first layer to be spread in an annular shape. By repeating this, the light incident from the surface on the first layer side of the diffusing member can be spread in the lateral direction. Therefore, when the diffusion member of the present disclosure is used in a direct-type LED backlight, the light emitted from the LED element can be diffused over the entire light-emitting surface, thereby further improving the in-plane uniformity of brightness and eliminating the need for alignment with the LED element.

[0044] Here, the intensity distribution can be measured using a goniophotometer or a goniospectrocolorimeter.

[0045] The first layer is not particularly limited as long as it has the above-mentioned light transmission and light diffusion properties, and various configurations having the above-mentioned light transmission and light diffusion properties can be adopted. Examples of the first layer include a transmission type diffraction grating, a microlens array, and a diffusion agent-containing resin film containing a diffusion agent and a resin. Specifically, when the first layer has a light diffusion property that mainly diffuses light in a specific direction, a transmission type diffraction grating and a microlens array can be mentioned. On the other hand, when the first layer has a light diffusion property that randomly diffuses light, a diffusion agent-containing resin film can be mentioned. Among them, from the viewpoint of light diffusion, a transmission type diffraction grating and a microlens array are preferable. Note that a transmission type diffraction grating is also called a transmission type diffractive optical element (DOE; Diffractive Optical Elements).

[0046] When the first layer is a transmission type diffraction grating, the transmission type diffraction grating is not particularly limited as long as it has the above-mentioned light transmitting and light diffusing properties.

[0047] The transmission type diffraction grating may be, for example, either a phase type diffraction grating or an amplitude type diffraction grating. The phase type diffraction grating may be, for example, either a relief type diffraction grating or a volume type diffraction grating. Among them, the transmission type diffraction grating is preferably a relief type diffraction grating. Furthermore, when the transmission type diffraction grating is a relief type diffraction grating, it is preferably a multi-level diffraction grating in which the cross-sectional shape of the groove has a step shape. In general, since the pitch of the diffraction grating of a multi-level diffraction grating is small, the present disclosure, which can eliminate the need for alignment between the diffusion member and the LED element, is particularly effective. In the multi-level diffraction grating, the number of levels can be, for example, 2 steps, 4 steps, 8 steps, 16 steps, etc. FIG. 6 is an example of a multi-level diffraction grating 2a with 4 levels.

[0048] In addition, examples of the transmission type diffraction grating include a transmission type diffraction grating that transmits and diffracts light and emits light having a non-Gaussian intensity distribution, and specifically, a transmission type diffraction grating that transmits and diffracts light and emits light having an annular intensity distribution, and a transmission type diffraction grating that transmits and diffracts light and emits light having a top-hat intensity distribution. Among them, the transmission type diffraction grating is preferably a transmission type diffraction grating that transmits and diffracts light and emits light having an annular intensity distribution, that is, a transmission type diffraction grating that transmits and diffracts light and emits transmission diffracted light with an annular intensity distribution in which the intensity of the transmission diffracted light emitted to the periphery is stronger than the intensity of the transmission diffracted light emitted to the center of the optical axis. In particular, it is preferably a transmission type diffraction grating that emits transmission diffracted light with an annular intensity distribution, and the intensity of the transmission diffracted light emitted to the center of the optical axis is almost zero, as shown in FIG. 4(a), for example. In the case of such a transmissive diffraction grating, when the diffusion member of the present disclosure is used in an LED backlight, the intensity of the light emitted toward the center of the optical axis can be reduced while the intensity of the light emitted toward the periphery can be increased, thereby further improving the in-plane uniformity of brightness.

[0049] In the case of a transmission type diffraction grating that transmits and diffracts light and emits light having an annular intensity distribution, the angle between the direction in which the intensity of the transmitted diffracted light is maximum in the annular intensity distribution and the normal direction of the transmission type diffraction grating can be, for example, 30° or more and 75° or less. If the angle is too small, the effect of spreading the light in the lateral direction cannot be sufficiently obtained, and it may be difficult to uniform the brightness. If the angle is too large, total reflection may occur, and it may be difficult to uniform the brightness. The angle may be, for example, 30° or more and 45° or less. If the angle is within the above range, it is easy to manufacture the transmission type diffraction grating.

[0050] Here, the intensity distribution and the angle can be measured using a goniophotometer or a goniospectrophotometer. For example, a goniophotometer GP-200 or a goniospectrophotometer GCMS-11 manufactured by Murakami Color Research Laboratory Co., Ltd. can be used to measure the angle.

[0051] The pitch of the transmission type diffraction grating is adjusted as appropriate so long as the above-mentioned light transmittance and light diffusion properties are obtained. Specifically, when the wavelength of the LED element is a single color such as red, green, or blue, the light from the LED element can be effectively bent by setting the pitch according to each wavelength.

[0052] Specifically, the pitch of the transmission diffraction grating can be 50 μm or more and 200 μm or less. As described above, the diffusing member of the present disclosure can eliminate the need for alignment with the LED element, and is therefore particularly effective when the pitch of the transmission diffraction grating is small as in the above range.

[0053] Furthermore, when the transmission grating is a relief type diffraction grating, the groove depth of the transmission grating can be, for example, not less than 1 μm and not more than 5 μm.

[0054] The pitch of a transmission grating, for example in the case of a multi-level diffraction grating, refers to the distance P between adjacent grooves as shown in Fig. 6. The groove depth of a transmission grating, for example in the case of a multi-level diffraction grating, refers to the maximum groove depth d1 as shown in Fig. 6.

[0055] Here, the pitch and groove depth of the transmission diffraction grating can be determined from a plan view micrograph or a cross-sectional micrograph in the thickness direction of the transmission diffraction grating observed with a transmission electron microscope (TEM), a scanning electron microscope (SEM) or a scanning transmission electron microscope (STEM).

[0056] The material constituting the transmission type diffraction grating may be any material that can provide a transmission type diffraction grating having the above-mentioned light transmittance and light diffusion properties, and may be any material that is generally used for transmission type diffraction gratings, such as glass such as quartz glass, resin, etc.

[0057] In addition, the method of forming the transmission type diffraction grating can be the same as the method of forming a general transmission type diffraction grating. When the transmission type diffraction grating is a multi-level diffraction grating, the method of forming the transmission type diffraction grating can be, for example, a method of processing a glass substrate such as a quartz substrate by lithography using a direct drawing method of an electron beam or a laser or lithography using a photomask, and a groove having a step shape can be formed in the glass substrate by repeatedly performing a lithography process and an etching process. In addition, another method of forming the transmission type diffraction grating can be resin shaping using a mold. In this case, for example, a resin layer can be formed on one side of the base layer, and the resin layer can be shaped by a mold to form a groove having a step shape in the resin layer, and a resin layer can be formed on one side of the second layer, and the resin layer can be shaped by a mold to form a groove having a step shape in the resin layer. As a method for manufacturing a mold, a molding die is first produced by processing a glass substrate such as a quartz substrate by the above-mentioned electron beam or laser direct drawing lithography or photomask lithography, and then an inverted die is produced using the molding die, and the inverted die can be used as the mold. As a method for designing a transmission type diffraction grating, for example, an iterative Fourier transform algorithm (IFTA) can be used.

[0058] When the first layer is a microlens array, the microlens array is not particularly limited as long as it has the above-mentioned light transmittance and light diffusibility.

[0059] In addition, examples of the microlens array include a microlens array that transmits and refracts light and emits light having a non-Gaussian intensity distribution, and specifically, a microlens array that transmits and refracts light and emits light having an annular intensity distribution, and a microlens array that transmits and refracts light and emits light having a top-hat intensity distribution. Among them, the microlens is preferably a microlens array that transmits and refracts light and emits light having an annular intensity distribution, that is, a microlens array that transmits and refracts light and emits transmitted and refracted light with an annular intensity distribution in which the intensity of the transmitted and refracted light emitted to the peripheral part is stronger than the intensity of the transmitted and refracted light emitted to the optical axis center. In the case of such a microlens array, when the diffusion member of the present disclosure is used in an LED backlight, the intensity of the light emitted to the optical axis center can be reduced and the intensity of the light emitted to the peripheral part can be increased, and the in-plane uniformity of the brightness can be further improved.

[0060] The shape, pitch, size, etc. of the microlenses may be appropriately adjusted so long as the above-mentioned light transmittance and light diffusion properties are obtained.

[0061] Specifically, the pitch of the microlenses of the microlens array can be 1 mm or less, and may be 0.6 mm or less. As described above, the diffusing member of the present disclosure does not require alignment with the LED elements, and is therefore particularly effective when the pitch of the microlenses is small as in the above range. The pitch of the microlenses can be, for example, 0.001 mm or more.

[0062] Here, the pitch of the microlenses can be determined from a planar micrograph or a cross-sectional micrograph in the thickness direction of the microlens array observed with a transmission electron microscope (TEM), a scanning electron microscope (SEM) or a scanning transmission electron microscope (STEM).

[0063] The material constituting the microlens may be any material that can provide a microlens having the above-mentioned light transmittance and light diffusion properties, and may be any material generally used for microlenses. The method for forming the microlens may be the same as the method for forming a general microlens.

[0064] When the first layer is a diffusing agent-containing resin film, the diffusing agent-containing resin film is not particularly limited as long as it has the above-mentioned light transmittance and light diffusibility.

[0065] The diffusing agent contained in the diffusing agent-containing resin film is not particularly limited as long as it can diffuse the light from the LED element, and can be a diffusing agent generally used in a diffusing plate used in an LED backlight. The content of the diffusing agent in the diffusing agent-containing resin film is not particularly limited as long as it can diffuse the light from the LED element, and can be the same as the content of the diffusing agent in a diffusing plate generally used in an LED backlight.

[0066] Furthermore, the resin contained in the diffusing agent-containing resin film is not particularly limited as long as it is capable of dispersing the diffusing agent, and resins generally used in diffusing plates for LED backlights can be used.

[0067] The first layer may have a structure capable of exhibiting light diffusion properties, and may exhibit light diffusion properties throughout the entire layer, or may exhibit light diffusion properties on a surface. Examples of the first layer that exhibit light diffusion properties on a surface include a relief type diffraction grating and a microlens array. On the other hand, examples of the first layer that exhibit light diffusion properties throughout the entire layer include a volume type diffraction grating and a resin film containing a diffusing agent.

[0068] As for the arrangement of the first layer and the second layer, for example, the first layer may be directly arranged on one surface of the second layer, the first layer may be arranged on one surface of the second layer via an adhesive layer or a pressure-sensitive adhesive layer, or the first layer 2 may be arranged on one surface of the second layer 3 via a gap as shown in FIG. 7(a). For example, when the first layer exhibits light diffusibility on a surface and has a structure capable of exhibiting light diffusibility on a surface facing the second layer, it is preferable that the first layer and the second layer are arranged via a gap. In addition, when the first layer is directly arranged on one surface of the second layer, the first layer 2 may be arranged in a pattern on one surface of the second layer 3, as shown in FIG. 7(b). For example, when the first layer exhibits light diffusibility on a surface, even when the first layer is arranged in a pattern, it is possible to exhibit light diffusibility.

[0069] When the first layer and the second layer are arranged with a gap therebetween, the first layer and the second layer may or may not be in contact with each other. When the first layer and the second layer are not in contact with each other, for example, a spacer may be arranged between the first layer and the second layer. The gap may be an air layer.

[0070] Examples of the method for laminating the first layer and the second layer include a method for bonding the first layer and the second layer via an adhesive layer or a pressure-sensitive adhesive layer, and a method for directly forming the first layer on one side of the second layer. Examples of the method for directly forming the first layer on one side of the second layer include a printing method, resin shaping using a mold, etc. In the case of the printing method or resin shaping using a mold, a patterned first layer can be directly formed on one side of the second layer.

[0071] 2.Second layer The second layer in the present disclosure is a member that is disposed on one side of the first layer, and has an incidence angle dependency of reflectance such that the reflectance increases as the absolute value of the incidence angle of light with respect to the surface of the second layer facing the first layer decreases, and an incidence angle dependency of transmittance such that the transmittance increases as the absolute value of the incidence angle of light with respect to the surface of the second layer facing the first layer increases.

[0072] The second layer has an incidence angle dependency of reflectance such that the reflectance increases as the absolute value of the incidence angle of light on the surface of the second layer on the first layer side decreases. That is, the reflectance of light incident at a low incidence angle on the surface of the second layer on the first layer side is greater than the reflectance of light incident at a high incidence angle on the surface of the second layer on the first layer side. In particular, it is preferable that the reflectance of light incident at a low incidence angle on the surface of the second layer on the first layer side is large.

[0073] Specifically, the specular reflectance of visible light incident on the surface of the second layer on the first layer side at an incident angle of ±60° or less is preferably 50% or more and less than 100%, more preferably 80% or more and less than 100%, and particularly preferably 90% or more and less than 100%. It is preferable that the specular reflectance of visible light satisfies the above range at all incident angles within the incident angle of ±60°. When the specular reflectance is within the above range, the in-plane uniformity of brightness can be improved when the diffusing member of the present disclosure is used in an LED backlight.

[0074] Moreover, the average regular reflectance of visible light incident on the surface of the second layer on the first layer side at an incident angle within ±60° is, for example, preferably 80% to 99%, more preferably 90% to 97%. The average regular reflectance refers to the average regular reflectance of visible light at each incident angle. When the average regular reflectance is within the above range, the in-plane uniformity of brightness can be improved when the diffusing member of the present disclosure is used in an LED backlight.

[0075] Furthermore, the specular reflectance of visible light incident at an incident angle of 0° (perpendicularly incident) on the surface of the second layer on the first layer side is, for example, preferably 80% or more and less than 100%, more preferably 90% or more and less than 100%, and particularly preferably 95% or more and less than 100%. When the specular reflectance is in the above range, the in-plane uniformity of luminance can be improved when the diffusing member of the present disclosure is used in an LED backlight.

[0076] In this specification, "visible light" refers to light having a wavelength of 380 nm or more and 780 nm or less. The regular reflectance can be measured using a goniophotometer or a goniospectrophotometer. For example, a goniophotometer GP-200 or a goniospectrophotometer GCMS-11 manufactured by Murakami Color Research Laboratory can be used to measure the regular reflectance.

[0077] In addition, the total light transmittance of light incident on the surface of the second layer on the first layer side at an incident angle of ±60° is, for example, preferably 10% or less, more preferably 5% or less, and particularly preferably 3% or less. It is preferable that the total light transmittance satisfies the above range at all incident angles within the incident angle of ±60°. If the total light transmittance is within the above range, the regular reflectance can be kept within a predetermined range, and when the diffusion member of the present disclosure is used in an LED backlight, the in-plane uniformity of brightness can be improved.

[0078] The second layer has an incidence angle dependency of transmittance such that the transmittance increases as the absolute value of the incidence angle of light on the surface of the second layer on the first layer side increases. That is, the transmittance of light incident on the surface of the second layer on the first layer side at a high incidence angle is greater than the transmittance of light incident on the surface of the second layer on the first layer side at a low incidence angle. In particular, the transmittance of light incident on the surface of the second layer on the first layer side at a high incidence angle is preferably large. Specifically, the total light transmittance of light incident on the surface of the second layer on the first layer side at an incidence angle of 70° or more and less than 90° is preferably 30% or more, more preferably 40% or more, and particularly preferably 50% or more. It is preferable that the total light transmittance satisfies the above range at all incidence angles of 70° or more and less than 90°. In addition, it is preferable that the total light transmittance satisfies the above range when the absolute value of the incidence angle is 70° or more and less than 90°. When the total light transmittance is in the above range, the in-plane uniformity of luminance can be improved when the diffusing member of the present disclosure is used in an LED backlight.

[0079] The total light transmittance of the second layer can be measured, for example, by a goniophotometer or a goniospectrophotometer according to a method conforming to JIS K7361-1:1997. For measuring the total light transmittance, for example, an ultraviolet-visible-near infrared spectrophotometer V-7200 manufactured by JASCO Corporation can be used. As the light source, CIE standard illuminant D65 can be used.

[0080] In addition, the regular reflectance of visible light incident on the surface of the second layer on the first layer side at an incident angle of 70° or more and less than 90° is, for example, preferably 70% or less, more preferably 60% or less, and particularly preferably 50% or less. It is preferable that the regular reflectance of visible light satisfies the above range at all incident angles of 70° or more and less than 90°. It is also preferable that the regular reflectance of visible light satisfies the above range when the absolute value of the incident angle is 70° or more and less than 90°. If the regular reflectance is within the above range, the total light transmittance can be set within a predetermined range, and when the diffusing member of the present disclosure is used in an LED backlight, the in-plane uniformity of luminance can be improved.

[0081] In addition, the average regular reflectance of visible light incident on the surface of the second layer on the first layer side at an incident angle of 70° or more and less than 90° is, for example, preferably 70% or less, more preferably 50% or less, and particularly preferably 30% or less. The average regular reflectance refers to the average regular reflectance of visible light at each incident angle. If the average regular reflectance is within the above range, the total light transmittance can be set within a predetermined range, and when the diffusing member of the present disclosure is used in an LED backlight, the in-plane uniformity of luminance can be improved.

[0082] The second layer is not particularly limited as long as it has the above-mentioned reflectance and transmittance dependence on the incident angle, and various configurations having the above-mentioned reflectance and transmittance dependence on the incident angle can be adopted. Examples of the second layer include a dielectric multilayer film, a reflection structure having a patterned first reflection film and a patterned second reflection film in order from the first layer side, the openings of the first reflection film and the openings of the second reflection film being positioned so as not to overlap in a plan view, and the first reflection film and the second reflection film being spaced apart in the thickness direction, and a reflection type diffraction grating.

[0083] Hereinafter, the case where the second layer is a dielectric multilayer film, a reflective structure, or a reflective diffraction grating will be described.

[0084] (1) Dielectric multilayer film When the second layer is a dielectric multilayer film, examples of the dielectric multilayer film include a multilayer film of an inorganic compound in which inorganic layers having different refractive indices are alternately laminated, and a multilayer film of a resin in which resin layers having different refractive indices are alternately laminated.

[0085] (Multilayer film of inorganic compounds) When the dielectric multilayer film is a multilayer film of an inorganic compound in which inorganic layers having different refractive indices are alternately laminated, the multilayer film of the inorganic compound is not particularly limited as long as it has the above-mentioned incidence angle dependence of reflectance and transmittance.

[0086] Among the inorganic layers having different refractive indices, the inorganic compound contained in the high refractive index inorganic layer having a high refractive index may have a refractive index of, for example, 1.7 or more, and may be 1.7 or more and 2.5 or less. Examples of such inorganic compounds include those containing titanium oxide, zirconium oxide, tantalum pentoxide, niobium pentoxide, lanthanum oxide, yttrium oxide, zinc oxide, zinc sulfide, or indium oxide as the main component, with small amounts of titanium oxide, tin oxide, cerium oxide, or the like.

[0087] Among the inorganic layers having different refractive indices, the inorganic compound contained in the low refractive index inorganic layer may have a refractive index of, for example, 1.6 or less, and may be 1.2 or more and 1.6 or less. Examples of such inorganic compounds include silica, alumina, lanthanum fluoride, magnesium fluoride, and sodium aluminum hexafluoride.

[0088] The number of stacked high refractive index inorganic layers and low refractive index inorganic layers is adjusted appropriately as long as the above-mentioned reflectance and transmittance are dependent on the incidence angle. Specifically, the total number of stacked high refractive index inorganic layers and low refractive index inorganic layers can be 4 or more. In addition, the upper limit of the total number of stacked layers is not particularly limited, but since the number of stacked layers increases, the number of steps increases, for example, it can be 24 or less.

[0089] The thickness of the inorganic compound multilayer film may be set to a value sufficient to obtain the above-mentioned incidence angle dependence of reflectance and transmittance, and may be set to, for example, 0.5 μm or more and 10 μm or less.

[0090] Examples of methods for forming a multilayer film of an inorganic compound include a method in which high refractive index inorganic layers and low refractive index inorganic layers are alternately laminated by a CVD method, a sputtering method, a vacuum deposition method, a wet coating method, or the like.

[0091] (multi-layer resin film) When the dielectric multilayer film is a resin multilayer film in which resin layers having different refractive indices are alternately laminated, the resin multilayer film is not particularly limited as long as it has the above-mentioned incidence angle dependence of reflectance and transmittance.

[0092] Examples of the resin constituting the resin layer include thermoplastic resins and thermosetting resins. Among them, thermoplastic resins are preferred because of their good moldability.

[0093] The resin layer may contain various additives, such as antioxidants, antistatic agents, crystal nucleating agents, inorganic particles, organic particles, viscosity reducers, heat stabilizers, lubricants, infrared absorbers, ultraviolet absorbers, and doping agents for adjusting the refractive index.

[0094] Examples of the thermoplastic resin include polyolefin resins such as polyethylene, polypropylene, polystyrene, and polymethylpentene, alicyclic polyolefin resins, polyamide resins such as nylon 6 and nylon 66, aramid resins, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, polybutyl succinate, and polyethylene-2,6-naphthalate, polycarbonate resins, polyarylate resins, polyacetal resins, polyphenylene sulfide resins, tetrafluoroethylene resins, trifluoroethylene resins, trifluorochloroethylene resins, tetrafluoroethylene-hexafluoropropylene copolymers, and fluororesins such as vinylidene fluoride resins, acrylic resins, methacrylic resins, polyacetal resins, polyglycolic acid resins, and polylactic acid resins. Among these, polyester is more preferable from the viewpoints of strength, heat resistance, and transparency.

[0095] In this specification, polyester refers to homopolyesters or copolymer polyesters that are polycondensates of dicarboxylic acid component skeletons and diol component skeletons. Examples of homopolyesters include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, poly-1,4-cyclohexanedimethylene terephthalate, and polyethylene diphenyl ester. Among them, polyethylene terephthalate is preferred because it is inexpensive and can be used in a wide variety of applications.

[0096] In this specification, the copolymer polyester is defined as a polycondensate consisting of at least three or more components selected from the following components having a dicarboxylic acid skeleton and components having a diol skeleton. Examples of the components having a dicarboxylic acid skeleton include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4-diphenyldicarboxylic acid, 4,4-diphenylsulfonedicarboxylic acid, adipic acid, sebacic acid, dimer acid, cyclohexanedicarboxylic acid, and ester derivatives thereof. Examples of the components having a glycol skeleton include ethylene glycol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, diethylene glycol, polyalkylene glycol, 2,2-bis(4-β-hydroxyethoxyphenyl)propane, isosorbate, 1,4-cyclohexanedimethanol, and spiroglycol.

[0097] Of the resin layers having different refractive indices, the difference in the in-plane average refractive index between the high refractive index resin layer and the low refractive index resin layer is preferably 0.03 or more, more preferably 0.05 or more, and even more preferably 0.1 or more. If the difference in the in-plane average refractive index is too small, sufficient reflectance may not be obtained.

[0098] In addition, the difference between the in-plane average refractive index and the thickness direction refractive index of the high refractive index resin layer is preferably 0.03 or more, and the difference between the in-plane average refractive index and the thickness direction refractive index of the low refractive index resin layer is preferably 0.03 or less. In this case, even if the incident angle increases, the reflectance of the reflection peak is unlikely to decrease.

[0099] As a preferred combination of the high refractive index resin used in the high refractive index resin layer and the low refractive index resin used in the low refractive index resin layer, firstly, the absolute value of the difference in SP value between the high refractive index resin and the low refractive index resin is preferably 1.0 or less. When the absolute value of the difference in SP value is within the above range, interlayer peeling is less likely to occur. In this case, it is more preferable that the high refractive index resin and the low refractive index resin contain the same basic skeleton. Here, the basic skeleton refers to the repeating unit constituting the resin. For example, when one resin is polyethylene terephthalate, the basic skeleton is ethylene terephthalate. Also, for example, when one resin is polyethylene, the basic skeleton is ethylene. When the high refractive index resin and the low refractive index resin are resins containing the same basic skeleton, peeling between layers is more unlikely to occur.

[0100] Secondly, as a preferred combination of the high refractive index resin used in the high refractive index resin layer and the low refractive index resin used in the low refractive index resin layer, the difference in glass transition temperature between the high refractive index resin and the low refractive index resin is preferably 20° C. or less. If the difference in glass transition temperature is too large, the thickness uniformity may be poor when forming a laminated film of the high refractive index resin layer and the low refractive index resin layer. In addition, overstretching may occur when forming the laminated film.

[0101] In addition, it is preferable that the high refractive index resin is polyethylene terephthalate or polyethylene naphthalate, and the low refractive index resin is a polyester containing spiro glycol. Here, the polyester containing spiro glycol refers to a copolyester copolymerized with spiro glycol, a homopolyester, or a polyester blended with them. Since the difference in glass transition temperature between spiro glycol and polyethylene terephthalate and polyethylene naphthalate is small, the polyester containing spiro glycol is less likely to be overstretched during molding and is less likely to delaminate, which is preferable. More preferably, the high refractive index resin is polyethylene terephthalate or polyethylene naphthalate, and the low refractive index resin is preferably a polyester containing spiro glycol and cyclohexane dicarboxylic acid. When the low refractive index resin is a polyester containing spiro glycol and cyclohexane dicarboxylic acid, the difference in in-plane refractive index between polyethylene terephthalate and polyethylene naphthalate is large, so that a high reflectance is easily obtained. In addition, since the difference in glass transition temperature between polyethylene terephthalate and polyethylene naphthalate is small and the adhesiveness is excellent, the polyester is less likely to be overstretched during molding and is less likely to delaminate.

[0102] It is also preferred that the high refractive index resin is polyethylene terephthalate or polyethylene naphthalate, and the low refractive index resin is a polyester containing cyclohexane dimethanol. Here, the polyester containing cyclohexane dimethanol refers to a copolyester copolymerized with cyclohexane dimethanol, a homopolyester, or a polyester blended with them. Polyester containing cyclohexane dimethanol is preferred because it is less likely to be overstretched during molding and less likely to peel off between layers due to its small difference in glass transition temperature from polyethylene terephthalate and polyethylene naphthalate. In this case, it is more preferred that the low refractive index resin is an ethylene terephthalate polycondensate in which the copolymerization amount of cyclohexane dimethanol is 15 mol% or more and 60 mol% or less. By doing so, while having high reflectivity, the change in optical properties due to heating or aging is particularly small, and peeling between layers is also less likely to occur. An ethylene terephthalate polycondensate in which the copolymerization amount of cyclohexane dimethanol is within the above range adheres very strongly to polyethylene terephthalate. In addition, the cyclohexanedimethanol group exists as geometric isomers (cis or trans) and as conformational isomers (chair or boat). Therefore, even when co-stretched with polyethylene terephthalate, it is less likely to undergo orientation crystallization, has high reflectance, shows even less change in optical properties due to thermal history, and is less likely to tear during film formation.

[0103] In the above-mentioned resin multilayer film, there may be a portion having a structure in which high-refractive index resin layers and low-refractive index resin layers are alternately laminated in the thickness direction. That is, it is preferable that the arrangement order of the high-refractive index resin layers and low-refractive index resin layers in the thickness direction is not random, and the arrangement order of the resin layers other than the high-refractive index resin layers and low-refractive index resin layers is not particularly limited. In addition, when the above-mentioned resin multilayer film has a high-refractive index resin layer, a low-refractive index resin layer, and other resin layers, it is more preferable that the layers are laminated in a regular order such as A(BCA)n, A(BCBA)n, A(BABCBA)n, etc., where A is the high-refractive index resin layer, B is the low-refractive index resin layer, and C is the other resin layer. Here, n is the number of repeating units, and for example, when n=3 in A(BCA)n, it represents that the layers are laminated in the order of ABCABCABCA in the thickness direction.

[0104] The number of layers of the high refractive index resin layer and the low refractive index resin layer may be appropriately adjusted as long as the above-mentioned dependence of the reflectance and the transmittance on the incident angle is obtained. Specifically, the high refractive index resin layer and the low refractive index resin layer may be alternately laminated in 30 layers or more, and may be laminated in 200 layers or more. The total number of layers of the high refractive index resin layer and the low refractive index resin layer may be, for example, 600 layers or more. If the number of layers is too small, sufficient reflectance may not be obtained. In addition, the desired reflectance can be easily obtained by the number of layers being within the above range. In addition, the upper limit of the total number of layers is not particularly limited, but considering the increase in size of the device and the decrease in lamination accuracy due to the number of layers becoming too large, it can be, for example, 1500 layers or less.

[0105] Furthermore, the multilayer film of the resin preferably has a surface layer containing polyethylene terephthalate or polyethylene naphthalate having a thickness of 3 μm or more on at least one side, and more preferably has the above surface layer on both sides. The thickness of the surface layer is more preferably 5 μm or more. By having the above surface layer, the surface of the multilayer film of the resin can be protected.

[0106] Examples of methods for producing the above-mentioned resin multilayer film include a co-extrusion method, etc. Specifically, reference can be made to the method for producing a laminated film described in JP-A-2008-200861.

[0107] As the multilayer film of the above resin, a commercially available laminate film can be used, and specific examples thereof include PICASUS (registered trademark) manufactured by Toray Industries, Inc. and ESR manufactured by 3M.

[0108] (2) Reflective structure The reflective structure has, in order from the first layer side, a patterned first reflective film and a patterned second reflective film, the openings of the first reflective film and the openings of the second reflective film are positioned so that they do not overlap in a planar view, and the first reflective film and the second reflective film are arranged apart in the thickness direction.

[0109] The reflection structure has two aspects. The first aspect of the reflection structure has a transparent substrate, a patterned first reflection film arranged on one surface of the transparent substrate, and a patterned second reflection film arranged on the other surface of the transparent substrate, the openings of the first reflection film and the openings of the second reflection film are positioned so as not to overlap in a plan view, and the first reflection film and the second reflection film are arranged apart in the thickness direction. The second aspect of the reflection structure has a transparent substrate, a patterned convex portion arranged on one surface of the transparent substrate and having light transmission, a patterned first reflection film arranged on the surface opposite to the transparent substrate side of the convex portion, and a patterned second reflection film arranged on the openings of the convex portion on one surface of the transparent substrate, the openings of the first reflection film and the openings of the second reflection film are positioned so as not to overlap in a plan view, and the first reflection film and the second reflection film are arranged apart in the thickness direction. Each aspect will be described below.

[0110] (First embodiment of the reflective structure) A first aspect of the reflective structure in the present disclosure has a transparent substrate, a patterned first reflective film arranged on one surface of the transparent substrate, and a patterned second reflective film arranged on the other surface of the transparent substrate, the openings of the first reflective film and the openings of the second reflective film being positioned so as not to overlap in a plan view, and the first reflective film and the second reflective film being spaced apart in the thickness direction. In the case of the reflective structure of this aspect, a first layer is arranged on the surface side of the reflective structure facing the first reflective film in the diffusing member of the present disclosure.

[0111] 8(a) and (b) are schematic plan views and cross-sectional views showing an example of the reflective structure of this embodiment, in which FIG. 8(a) is a plan view of the reflective structure seen from the surface on the first reflective film side, and FIG. 8(b) is a cross-sectional view of line AA in FIG. 8(a). As shown in FIG. 8(a) and (b), the reflective structure 20 has a transparent substrate 21, a patterned first reflective film 22 arranged on one surface of the transparent substrate 21, and a second reflective film 24 arranged on the other surface of the transparent substrate 21. The openings 23 of the first reflective film 22 and the openings 25 of the second reflective film 24 are positioned so as not to overlap in a plan view. In addition, the first reflective film 22 and the second reflective film 24 are respectively arranged on both sides of the transparent substrate 21, and are arranged apart in the thickness direction. In FIG. 8(a), the openings of the second reflective film are indicated by dashed lines. In addition, FIG. 8(c) is a schematic cross-sectional view showing an example of an LED backlight including a diffusing member having the reflective structure of this embodiment.

[0112] In such a reflective structure, the patterned first and second reflective films are laminated, and the openings of the first and second reflective films are positioned so as not to overlap in a plan view, so that when a diffusing member having the reflective structure of this embodiment is used in an LED backlight, at least one of the first reflective film 22 and the second reflective film 24 is always present directly above the LED element 13, as shown in Fig. 8(c), for example. Therefore, as shown in Fig. 8(b), for example, light L11 incident at a low incident angle on the surface of the reflective structure 20 on the first reflective film 22 side, i.e., the surface 3A on the side where the first layer (not shown) of the reflective structure 20 (second layer) is disposed, can be reflected by the first reflective film 22 and the second reflective film 24. In addition, since the openings of the first reflecting film and the openings of the second reflecting film are positioned so as not to overlap in a plan view, and the first reflecting film and the second reflecting film are arranged apart in the thickness direction, the light L12 and L13 incident at a high incident angle on the surface of the reflecting structure 20 on the first reflecting film 22 side, i.e., the surface 3A on the side on which the first layer (not shown) of the reflecting structure 20 (second layer) is arranged, can be emitted from the opening 23 of the first reflecting film 22 and the opening 25 of the second reflecting film 24. This makes it possible to emit a part of the light emitted from the LED element and then emitted from the surface on the second layer side of the diffusing member from a position away from the LED element in the in-plane direction, rather than directly above the LED element. This makes it possible to improve the in-plane uniformity of the luminance.

[0113] The reflecting structure of this embodiment will be described below.

[0114] The first and second reflective films may be general reflective films, such as metal films, dielectric multilayer films, etc. The metal film may be made of a metal material used in general reflective films, such as aluminum, gold, silver, and alloys thereof. The dielectric multilayer film may be made of a material used in general reflective films, such as inorganic compound multilayer films in which zirconium oxide and silicon oxide are alternately laminated. The materials contained in the first and second reflective films may be the same or different from each other.

[0115] The pitch of the openings of the first and second reflective films may be set appropriately depending on the light distribution characteristics, size, pitch, and shape of the LED elements in the LED backlight in which the diffusing member of the present disclosure is used, the distance between the LED substrate and the diffusing member, etc. The pitch of the openings of the first and second reflective films may be the same or different from each other.

[0116] The pitch of the openings in the first reflective film may be larger than the size of the LED elements, for example. Specifically, the pitch of the openings in the first reflective film may be set to be 0.1 mm or more and 20 mm or less.

[0117] In addition, the pitch of the openings of the second reflective film is not particularly limited as long as it can suppress brightness unevenness, but it is preferably equal to or smaller than the pitch of the openings of the first reflective film, and is preferably smaller than the pitch of the openings of the first reflective film. Specifically, the pitch of the openings of the second reflective film can be 0.1 mm or more and 2 mm or less. By making the pitch of the openings of the second reflective film fine as described above, the pattern of the second reflective film and the openings of the second reflective film can be made difficult to see, and surface emission without unevenness can be achieved.

[0118] The pitch of the openings in the first reflective film refers to the distance P1 between the centers of the openings 23 in the adjacent first reflective film 22, as shown in Fig. 8(a), for example. The pitch of the openings in the second reflective film refers to the distance P2 between the centers of the openings 25 in the adjacent second reflective film 24, as shown in Fig. 8(a), for example.

[0119] The size of the openings of the first and second reflective films may be set appropriately depending on the light distribution characteristics, size, pitch, and shape of the LED elements in the LED backlight in which the diffusing member of the present disclosure is used, the distance between the LED substrate and the diffusing member, etc. The size of the openings of the first and second reflective films may be the same or different from each other as long as the above-mentioned dependence of reflectance and transmittance on the incident angle is obtained.

[0120] Specifically, when the opening of the first reflective film has a rectangular shape, the size of the opening can be set to a length of 0.1 mm or more and 5 mm or less.

[0121] The size of the opening of the second reflective film is not particularly limited as long as it can suppress the unevenness of the brightness, but it is preferably equal to or smaller than the size of the opening of the first reflective film, and is preferably smaller than the size of the opening of the first reflective film. Specifically, when the shape of the opening of the second reflective film is rectangular, the length of the opening of the second reflective film can be 0.05 mm or more and 2 mm or less. By making the size of the opening of the second reflective film fine as described above, the pattern of the part of the second reflective film and the part of the opening of the second reflective film can be made difficult to see, and uneven surface emission can be achieved.

[0122] The size of the opening of the first reflective film refers to the length x1 of the opening 23 of the first reflective film 22 when the opening of the first reflective film has a rectangular shape, as shown in Fig. 8(a). The size of the opening of the second reflective film refers to the length x2 of the opening 25 of the second reflective film 24, as shown in Fig. 8(a).

[0123] The shape of the openings in the first reflective film and the second reflective film can be any shape, for example, rectangular, circular, or the like.

[0124] The thickness of the first and second reflective films may be adjusted appropriately so long as the above-mentioned dependence of reflectance and transmittance on the incident angle is obtained. Specifically, the thickness of the first and second reflective films may be set to 0.05 μm or more and 100 μm or less.

[0125] The first and second reflective films may be formed on the surface of a transparent substrate, or may be sheet-shaped reflective films. The method of forming the first and second reflective films is not particularly limited as long as it can form a patterned reflective film on the surface of the transparent substrate, and examples of the method include sputtering and vacuum deposition. In addition, when the first and second reflective films are sheet-shaped reflective films, examples of the method of forming the openings include a method of forming a plurality of through holes by punching or the like. In this case, examples of the method of laminating the transparent substrate and the sheet-shaped reflective film include a method of laminating the sheet-shaped reflective film to the transparent substrate via an adhesive layer or a pressure-sensitive adhesive layer.

[0126] The transparent substrate in the reflective structure of this embodiment is a member that supports the above-mentioned first reflective film and second reflective film, and is also a member for arranging the first reflective film and the second reflective film at a distance from each other in the thickness direction.

[0127] The transparent substrate has light transmittance. The light transmittance of the transparent substrate is preferably, for example, 80% or more, and more preferably 90% or more. The total light transmittance of the transparent substrate can be measured, for example, by a method conforming to JIS K7361-1:1997. The CIE standard illuminant D65 can be used as the light source.

[0128] The material constituting the transparent substrate may be any material having the total light transmittance described above, and examples of such materials include resins such as polyethylene terephthalate, polycarbonate, acrylic, cycloolefin, polyester, polystyrene, and acrylic styrene, and glasses such as quartz glass, Pyrex (registered trademark), and synthetic quartz.

[0129] 8(b), the thickness of the transparent base material is preferably such that light L12 incident at a high incident angle on the surface of the reflection structure 20 on the first reflection film 22 side, i.e., the surface 3A on the side where the first layer (not shown) of the reflection structure 20 (second layer) is arranged, can be emitted from the opening 23 of the first reflection film 22 and the opening 25 of the second reflection film 24, and is appropriately set according to the pitch and size of the openings of the first reflection film and the second reflection film, the thickness of the first reflection film and the second reflection film, etc. Specifically, the thickness of the transparent base material can be 0.05 mm or more and 2 mm or less, and preferably 0.1 mm or more and 0.5 mm or less.

[0130] (Second embodiment of the reflective structure) A second embodiment of the reflective structure of the present disclosure has a transparent substrate, a patterned convex portion having light transparency and disposed on one surface of the transparent substrate, a patterned first reflective film disposed on the surface opposite to the transparent substrate side of the convex portion, and a patterned second reflective film disposed at the opening of the convex portion on one surface of the transparent substrate, the opening of the first reflective film and the opening of the second reflective film being positioned so as not to overlap in a plan view, and the first reflective film and the second reflective film being disposed apart in the thickness direction. In the case of the reflective structure of this embodiment, in the diffusing member of the present disclosure, a first layer is disposed on the surface side of the reflective structure facing the first reflective film.

[0131] 9(a) and (b) are schematic plan views and cross-sectional views showing an example of a second embodiment of the reflective structure of the present disclosure, in which FIG. 9(a) is a plan view of the reflective structure seen from the surface on the first reflective film side, and FIG. 9(b) is a cross-sectional view of line AA in FIG. 9(a). As shown in FIG. 9(a) and (b), the reflective structure 20 has a transparent substrate 21, a patterned convex portion 26 having light transmission arranged on one surface of the transparent substrate 21, a patterned first reflective film 22 arranged on the surface opposite to the transparent substrate 21 side surface of the convex portion 26, and a patterned second reflective film 24 arranged at the opening of the convex portion 26 on one surface of the transparent substrate 21. The opening 23 of the first reflective film 22 and the opening 25 of the second reflective film 24 are positioned so as not to overlap in a plan view. In addition, the first reflective film 22 and the second reflective film 24 are separated by the convex portion 26 and arranged apart in the thickness direction.

[0132] In such a reflective structure, the patterned first and second reflective films are laminated, and the openings of the first and second reflective films are positioned so as not to overlap in a plan view, so that when a diffusing member having the reflective structure of this embodiment is used in an LED backlight, at least one of the first and second reflective films is always present directly above the LED element. Therefore, as in the first embodiment, for example, as shown in Fig. 9(b), light L11 incident at a low incident angle on the surface of the reflective structure 20 on the first reflective film 22 side, i.e., the surface 3A on the side where the first layer (not shown) of the reflective structure 20 (second layer) is arranged, can be reflected by the first reflective film 22 and the second reflective film 24. In addition, since the openings of the first reflecting film and the openings of the second reflecting film are positioned so as not to overlap in a plan view, and the first reflecting film and the second reflecting film are arranged apart in the thickness direction, the light L12 incident at a high incident angle on the surface of the reflecting structure 20 on the first reflecting film 22 side, i.e., the surface 3A on the side on which the first layer (not shown) of the reflecting structure 20 (second layer) is arranged, can be emitted from the side surface of the convex portion 26 and the opening 25 of the second reflecting film 24. As a result, a part of the light emitted from the LED element and then emitted from the surface on the second layer side of the diffusing member can be emitted from a position away from the LED element in the in-plane direction, rather than directly above the LED element. Therefore, the in-plane uniformity of the brightness can be improved.

[0133] Furthermore, in this embodiment, since the convex portion is provided, self-alignment of the openings in the first reflective film and the second reflective film is possible, and the manufacturing cost can be reduced.

[0134] The material of the first reflective film and the second reflective film, the pitch of the openings in the first reflective film and the second reflective film, the size of the openings in the first reflective film and the second reflective film, the shape of the openings in the first reflective film and the second reflective film, the thickness of the first reflective film and the second reflective film, and the method of forming the first reflective film and the second reflective film may be the same as in the first embodiment.

[0135] Moreover, the transparent substrate may be the same as that of the first embodiment.

[0136] The convex portion in the reflective structure of this embodiment is a member for arranging the first reflective film and the second reflective film at a distance from each other in the thickness direction.

[0137] The convex portion has light transmittance. The light transmittance of the convex portion is preferably, for example, 80% or more, and more preferably 90% or more. The total light transmittance of the convex portion can be measured by a method conforming to JIS K7361-1:1997, for example. The CIE standard illuminant D65 can be used as the light source.

[0138] The material for forming the convex portions may be any material that can form patterned convex portions and has the above-mentioned total light transmittance, and examples of such materials include thermosetting resins and electron beam curable resins.

[0139] 9(b), for example, the height of the convex portion is preferably such that light L12 incident at a high incident angle on the surface of the reflecting structure 20 on the first reflecting film 22 side, i.e., the surface 3A on the side where the first layer (not shown) of the reflecting structure 20 (second layer) is arranged, can be emitted from the side surface of the convex portion 26 and the opening 25 of the second reflecting film 24, and is appropriately set according to the pitch and size of the openings of the first reflecting film and the second reflecting film, the thickness of the first reflecting film and the second reflecting film, etc. Specifically, the height of the convex portion can be 0.05 mm or more and 2 mm or less, and preferably 0.1 mm or more and 0.5 mm or less.

[0140] The pitch, size and planar shape of the convex portions may be the same as the pitch, size and shape of the openings of the second reflective film.

[0141] The surface of the convex portion may be a smooth surface as shown in Fig. 9(b), or may be a rough surface as shown in Fig. 10(a). When the surface of the convex portion is a rough surface, the convex portion can be provided with light diffusing properties.

[0142] The shape of the surface of the convex portion may be flat as shown in Fig. 9(b) or curved as shown in Fig. 10(b). When the surface of the convex portion is curved, the convex portion can be provided with light diffusing properties.

[0143] The method for forming the convex portions is not particularly limited as long as it is a method capable of forming patterned convex portions, and examples thereof include a printing method and resin shaping using a mold.

[0144] (3) Reflective diffraction grating When the second layer is a reflective diffraction grating, the reflective diffraction grating is not particularly limited as long as it has the above-mentioned incidence angle dependence of reflectance and transmittance.

[0145] The pitch of the reflective diffraction grating is adjusted as appropriate so long as the above-mentioned reflectance and transmittance are dependent on the incident angle. Specifically, when the wavelength of the LED element is a single color such as red, green, or blue, the light of the LED element can be effectively reflected by setting the pitch according to each wavelength.

[0146] The material constituting the reflective diffraction grating may be any material that can provide a reflective diffraction grating having the above-mentioned incidence angle dependency of reflectance and transmittance, and may be any material that is generally used for reflective diffraction gratings. The method for forming the reflective diffraction grating may be the same as the method for forming a general reflective diffraction grating.

[0147] 3. Diffusion material In this embodiment, the overall thickness of the diffusing member can be, for example, not less than 30 μm and not more than 200 μm.

[0148] 4. Wavelength conversion materials In the diffusing member of the present disclosure, for example, as shown in Fig. 11(a), the wavelength conversion member 4 may be disposed on the surface of the second layer 3 opposite to the surface facing the first layer 2, or as shown in Fig. 11(b), the wavelength conversion member 4 may be disposed on the surface of the first layer 2 opposite to the surface facing the second layer 3. In LED backlights, wavelength conversion members are sometimes used to achieve a wider color gamut, and when the diffusing member of the present disclosure is used in an LED backlight, the wavelength conversion member may be combined with the diffusing member.

[0149] The wavelength conversion member is a member that contains a phosphor that absorbs the light emitted from the LED element and emits excitation light. The wavelength conversion member has the function of generating white light when combined with the LED substrate.

[0150] The wavelength conversion member usually has at least a wavelength conversion layer containing a phosphor and a resin. The wavelength conversion member may be, for example, a wavelength conversion layer alone, or a laminate having a wavelength conversion layer on one side of a transparent substrate. Among them, a wavelength conversion layer alone is preferred from the viewpoint of thinning. More preferably, a sheet-shaped wavelength conversion member is used.

[0151] The phosphor can be appropriately selected according to the color of light emitted from the LED element, and examples thereof include blue phosphor, green phosphor, red phosphor, yellow phosphor, etc. For example, when the LED element is a blue LED element, the phosphor may be a green phosphor and a red phosphor, or a yellow phosphor. Also, when the LED element is an ultraviolet LED element, the phosphor may be a red phosphor, a green phosphor, and a blue phosphor.

[0152] The phosphor can be any phosphor commonly used in wavelength conversion materials for LED backlights, or quantum dots can be used as the phosphor.

[0153] The content of the phosphor in the wavelength conversion material layer is not particularly limited as long as it is sufficient to generate the desired white light when the diffusion material of the present disclosure is used in an LED backlight, and can be similar to the content of the phosphor in the wavelength conversion material of a typical LED backlight.

[0154] The resin contained in the wavelength conversion member is not particularly limited as long as it can disperse the phosphor. The resin may be the same as the resin used in the wavelength conversion member of a general LED backlight, and examples of the resin include thermosetting resins such as silicone resins and epoxy resins.

[0155] The thickness of the wavelength conversion member is not particularly limited as long as it is a thickness that can generate the desired white light when the diffusion member of the present disclosure is used in an LED backlight, and can be, for example, 10 μm or more and 1000 μm or less.

[0156] Examples of the method for laminating the wavelength conversion member on the first layer or the second layer include a method for bonding the wavelength conversion member to the first layer or the second layer via an adhesive layer or a pressure-sensitive adhesive layer, a method for directly forming the wavelength conversion member on the surface of the first layer or the second layer, etc. Examples of the method for directly forming the wavelength conversion member on the surface of the first layer or the second layer include a printing method.

[0157] 5.Optical Components In the diffusing member of the present disclosure, for example, as shown in Fig. 11(b), an optical member 5 may be further disposed on the surface of the second layer 3 opposite to the surface on the first layer 2 side. In an LED backlight, an optical member may be used in addition to the diffusing member, and when the diffusing member of the present disclosure is used in an LED backlight, the diffusing member may be combined with an optical member. Examples of optical members include a prism sheet and a reflective polarizing sheet.

[0158] (1) Prism sheet The prism sheet in the present disclosure has a function of concentrating incident light and improving the luminance in a concentrated front direction. The prism sheet is, for example, a transparent resin substrate having a prism pattern including an acrylic resin or the like disposed on one side thereof.

[0159] As the prism sheet, for example, a brightness enhancing film BEF series manufactured by 3M can be used.

[0160] (2) Reflective polarizing sheet The reflective polarizing sheet in the present disclosure has a function of transmitting only a first linearly polarized component (e.g., P-polarized light) and reflecting a second linearly polarized component (e.g., S-polarized light) orthogonal to the first linearly polarized component without absorbing it. The second linearly polarized component reflected by the reflective polarizing sheet is reflected again and enters the reflective polarizing sheet again in a depolarized state (a state including both the first linearly polarized component and the second linearly polarized component). Thus, the reflective polarizing sheet transmits the first linearly polarized component of the re-entering light, and reflects again the second linearly polarized component orthogonal to the first linearly polarized component. By repeating the above process, about 70% to 80% of the light emitted from the second layer is output as the first linearly polarized component. Therefore, when an LED backlight equipped with the diffusing member of the present disclosure is used in a display device, by aligning the polarization direction of the first linearly polarized component (transmission axis component) of the reflective polarizing sheet with the transmission axis direction of the polarizing plate of the display panel, all of the light emitted from the LED backlight can be used for image formation on the display panel. Therefore, even if the light energy input from the LED element is the same, it is possible to form an image with higher brightness than when the reflective polarizing sheet is not provided.

[0161] Examples of the reflective polarizing sheet include the DBEF series brightness enhancement film manufactured by 3M Co., Ltd. In addition, examples of the reflective polarizing sheet that can be used include the WRPS high brightness polarizing sheet manufactured by Shinwha Intertek Co., Ltd., wire grid polarizer, and the like.

[0162] 6.Applications The diffusion member of the present disclosure is suitable for use in a direct type LED backlight.

[0163] II. Second embodiment of the diffusion member A second embodiment of the diffusion member of the present disclosure is a member having a transmission type diffraction grating or a microlens array and a dielectric multilayer film. When the diffusion member of the second embodiment of the present disclosure is used, the surface on the transmission type diffraction grating or the microlens array side is used as the light incidence surface.

[0164] In the second embodiment of the diffusing member of the present disclosure, by combining a transmission type diffraction grating or a microlens array with a dielectric multilayer film, it is possible to achieve the same effects as those of the first embodiment of the diffusing member described above.

[0165] The transmission type diffraction grating and the microlens array in this embodiment may be similar to the transmission type diffraction grating and the microlens array used in the first layer in the first embodiment of the diffusing member described above.

[0166] The dielectric multilayer film in this embodiment may be the same as the dielectric multilayer film used for the second layer in the first embodiment of the diffusing member described above.

[0167] The transmission type diffraction grating and the microlens array may have a structure capable of exhibiting light diffusion properties, for example, they may exhibit light diffusion properties throughout the entire layer, or may exhibit light diffusion properties over a surface.

[0168] The arrangement of the transmission grating or microlens array and the dielectric multilayer film may be, for example, such that the transmission grating or microlens array is arranged on one surface of the dielectric multilayer film via an adhesive layer or a pressure-sensitive adhesive layer, the transmission grating or microlens array may be arranged on one surface of the dielectric multilayer film via a gap, or the transmission grating or microlens array may be arranged directly on one surface of the dielectric multilayer film.

[0169] When the transmission grating or the microlens array and the dielectric multilayer film are arranged with a gap therebetween, the transmission grating or the microlens array and the dielectric multilayer film may or may not be in contact with each other. When the transmission grating or the microlens array and the dielectric multilayer film are not in contact with each other, for example, a spacer may be arranged between the transmission grating or the microlens array and the dielectric multilayer film. The gap may be an air layer.

[0170] Furthermore, in the case where a transmission type diffraction grating or a microlens array is directly disposed on one surface of the dielectric multilayer film, the transmission type diffraction grating or the microlens array can be directly formed on one surface of the dielectric multilayer film, for example, by a printing method or resin shaping using a mold.

[0171] The overall thickness of the diffusing member in this embodiment can be the same as the overall thickness of the diffusing member in the above-mentioned first embodiment.

[0172] In the diffusing member of this embodiment, a wavelength conversion member may be disposed on the surface of the dielectric multilayer film opposite to the surface of the transmission grating or the microlens array, or a wavelength conversion member may be disposed on the surface of the transmission grating or the microlens array opposite to the surface of the dielectric multilayer film. Note that the wavelength conversion member may be the same as the wavelength conversion member described in the first embodiment of the diffusing member described above.

[0173] In the diffusing member of this embodiment, an optical member may be disposed on the surface of the dielectric multilayer film opposite to the transmission type diffraction grating or the microlens array side. The optical member may be the same as the optical member described in the first embodiment of the diffusing member described above.

[0174] The diffusion member of this embodiment is suitable for use in a direct type LED backlight.

[0175] B. Laminate The laminate in the present disclosure has two embodiments, each of which will be described below.

[0176] I. First embodiment of the laminate A first embodiment of the laminate of the present disclosure includes a diffusing member having a first layer and a second layer in this order, and an encapsulant sheet disposed on the first layer side of the diffusing member and used to encapsulate an LED element, the first layer having light transmittance and light diffusing properties, the second layer having a reflectance that increases as the absolute value of the incident angle of light to the first layer side surface of the second layer decreases, and a transmittance that increases as the absolute value of the incident angle of light to the first layer side surface of the second layer increases, and the encapsulant sheet is a member made of an encapsulant composition containing a thermoplastic resin. When using the laminate of the present disclosure, the surface on the encapsulant sheet side is used as the light incident surface of the LED element.

[0177] FIG. 12 is a schematic cross-sectional view showing an example of the first embodiment of the laminate of the present disclosure. As illustrated in FIG. 12, the laminate 40 includes a diffusing member 1 having a first layer 2 and a second layer 3 in this order, and an encapsulant sheet 21a disposed on the surface of the diffusing member 1 facing the first layer 2 and used to encapsulate an LED element. The first layer 2 of the diffusing member 1 has light transmissivity and light diffusivity. The second layer 3 of the diffusing member 1 has a reflectance that increases as the absolute value of the incident angle of light to the surface of the second layer 3 facing the first layer 2 decreases, and a transmittance that increases as the absolute value of the incident angle of light to the surface of the second layer 3 facing the first layer 2 increases. The encapsulant sheet 21a is composed of an encapsulant composition containing a thermoplastic resin.

[0178] Here, the direct type LED backlight is at a disadvantage compared to the edge light type, particularly in terms of thinness and weight reduction, but as mentioned above, it is difficult to make the direct type LED backlight thin.

[0179] In recent years, research and development into miniaturization and high density of LED elements has been progressing, and LEDs with small chip size, so-called mini LEDs and micro LEDs, are attracting attention. Furthermore, it is being considered to put the technology of miniaturization and high density of LED elements into practical use as LED backlights (see, for example, Patent Document 4).

[0180] In direct-type LED backlights, brightness unevenness depends on the distance between the LED elements and the diffusion plate, as well as the distance between the LED elements (hereinafter sometimes referred to as the pitch). Therefore, brightness unevenness can also be suppressed by shortening the distance between the LED elements. In other words, by arranging fine LED elements at high density, the in-plane brightness uniformity can be improved. In this case, it becomes possible to achieve a thinner design.

[0181] Here, in LED backlights, spacers are placed to maintain a predetermined distance between the LED elements and the diffusion plate. However, the light emitted from the LED elements may be blocked or reflected by the spacers, resulting in uneven brightness. In addition, a large number of spacers must be provided, but when the pitch is fine, such as in mini LEDs or micro LEDs, it is difficult to place a large number of spacers.

[0182] Therefore, in LED backlights, a configuration has been proposed in which a sealing member that seals the LED elements is disposed between the LED elements and the diffusion plate (see, for example, Patent Document 4). However, a configuration in which a sealing member is disposed between the LED elements and the diffusion plate increases the weight compared to a configuration in which there is a space between the LED elements and the diffusion plate.

[0183] In recent years, there has been a demand for thinner and lighter display devices, and further thinner and lighter backlights are also required for those devices. As mentioned above, direct-type LED backlights are at a disadvantage in terms of thinner and lighter weight compared to edge-light-type backlights, and further improvements are required.

[0184] According to the present disclosure, by using the above-mentioned diffusing member, it is possible to improve the in-plane uniformity of brightness while reducing the thickness. In addition, since the distance between the LED element and the diffusing member can be shortened, the thickness of the encapsulant sheet can be reduced, and the weight can be reduced.

[0185] In the present disclosure, the encapsulant sheet is composed of an encapsulant composition containing a thermoplastic resin. The reason why a thermoplastic resin is preferred will be described below.

[0186] In the case where the sealing member in the LED backlight contains a thermoplastic resin, a sheet-like sealing material (hereinafter, sometimes referred to as a sealing material sheet) composed of a sealing material composition containing a thermoplastic resin can be used. Fig. 13(a)-(b) are process diagrams showing an example of a manufacturing method of an LED backlight in the present disclosure, which is an example using a laminate in the present disclosure. For example, as shown in Fig. 13(a), an LED substrate 11 and a laminate 40 of a diffusion member 1 and a sealing material sheet 21a are prepared, and the sealing material sheet 21a is laminated on the surface side of the LED substrate 11 on the LED element 13 side, and then, for example, by using a vacuum lamination method, the sealing material sheet 21a is pressed against the LED substrate 11, so that the LED element 13 can be sealed with the sealing member 21 as shown in Fig. 13(b). Note that Figs. 13(a) and (b) show an example in which a reflective layer 15 is arranged on the surface of the LED substrate 11 on which the LED element 13 of the support substrate 12 is arranged, except for the LED element mounting area where the LED element 13 is mounted.

[0187] On the other hand, in the case of an LED backlight, when the sealing member contains a curable resin such as a thermosetting resin or a photocurable resin, a liquid sealing member is usually used. In this case, for example, as shown in Fig. 14(a), a mold 101 is arranged around the LED substrate 11, and a liquid sealing member 21b containing a curable resin is applied to the surface of the LED substrate 11 facing the LED elements 13 to form a coating film, and then the coating film is cured by heat treatment, so that the LED elements 13 can be sealed with a sealing member 21' as shown in Fig. 14(b).

[0188] In the case of curable resin, a liquid sealing material is used, so due to surface tension and other factors, a phenomenon may occur in which the thickness of the edge portion is thicker or thinner than that of the center portion (see Figure 14(a)).

[0189] Furthermore, in the case of a curable resin, shrinkage of the volume is likely to occur during curing, and as a result, the thickness of the cured sealing member may become uneven between the center and the ends, as shown in Fig. 14(b). Note that Fig. 14(b) shows an example in which the thickness of the ends of the sealing member 21' is thicker than the thickness of the center, but the thickness distribution is not limited to this, and for example, the thickness of the ends may be thinner than the thickness of the center.

[0190] When the thickness of the sealing member differs between the center and the ends in this way, for example when multiple LED backlights are tiled to make them larger, the thickness at the boundaries between the individual LED backlights will differ, resulting in a noticeable seam. Therefore, when tiled LED backlights are used in a display device, the aesthetic appearance of the display may be impaired.

[0191] In contrast, when a sheet-like encapsulant is used, it is possible to avoid the occurrence of surface irregularities of the encapsulant, such as the occurrence of thickness distribution of the coating film due to surface tension and the occurrence of thickness distribution due to thermal or optical shrinkage, which occurs when a liquid encapsulant is used. Therefore, a encapsulant with good flatness can be obtained, and a high-quality display device can be provided. Therefore, according to the present disclosure, by having the above-mentioned encapsulant sheet, it is possible to obtain a encapsulant with good flatness. In particular, it is useful when tiling using an LED substrate of a size called a mini LED or micro LED.

[0192] A first embodiment of the laminate of the present disclosure will be described below.

[0193] 1. Diffusion material The diffusion member in the present disclosure is the same as that described in the above section "A. Diffusion member I. First embodiment."

[0194] The arrangement of the diffusing member and the sealant sheet is appropriately selected depending on the type of the first layer of the diffusing member, etc. For example, as shown in FIG. 12, the first layer 2 may be arranged directly or via an adhesive layer or pressure-sensitive adhesive layer (not shown) on one side of the second layer 3 of the diffusing member 1, and the sealant sheet 21a may be arranged directly on the side of the first layer 2 of the diffusing member 1; as shown in FIG. 15(a), the first layer 2 may be arranged directly or via an adhesive layer or pressure-sensitive adhesive layer (not shown) on one side of the second layer 3 of the diffusing member 1, and the sealant sheet 21a may be arranged via a low refractive index layer 43 on the side of the first layer 2 of the diffusing member 1; as shown in FIG. 15(b), the first layer 2 of the diffusing member 1 may be arranged directly on one side of the sealant sheet 21a, and a gap may be arranged between the first layer 2 and the second layer 3 of the diffusing member 1; or as shown in FIG. 15(c), the first layer 2 may be arranged directly on one side of the second layer 3 of the diffusing member 1, and a gap may be arranged between the diffusing member 1 and the sealant sheet 21a. When the first layer of the diffusing member is, for example, a diffusing agent-containing resin film, the diffusing member and the sealing material sheet may be arranged in any of the arrangements described above. On the other hand, when the first layer of the diffusing member is, for example, a transmission type diffraction grating or a microlens array, it is necessary that a gap be disposed between the first layer and the second layer of the diffusing member, or that a gap be disposed between the first layer of the diffusing member and the sealing material sheet, or that a low refractive index layer be disposed between the first layer of the diffusing member and the sealing material sheet.

[0195] In addition, when the first layer of the diffusion member is directly disposed on one surface of the encapsulant sheet, for example, as shown in Fig. 15(b), a patterned first layer 2 may be disposed on one surface of the encapsulant sheet 21a. For example, when the first layer exhibits light diffusibility on a surface, the light diffusibility can be exhibited even when the first layer is disposed in a pattern.

[0196] When a gap is disposed between the first layer and the second layer of the diffusing member, the first layer 2 and the second layer 3 may be in contact with each other as shown in FIG. 15(b), or the first layer and the second layer may not be in contact with each other, although not shown. When the first layer and the second layer are not in contact with each other, for example, a spacer may be disposed between the first layer and the second layer. When a gap is disposed between the diffusing member and the sealing material sheet, for example, the first layer of the diffusing member and the sealing material sheet may be in contact with each other, or the first layer of the diffusing member and the sealing material sheet may not be in contact with each other, as shown in FIG. 15(c). When the first layer of the diffusing member and the sealing material sheet are not in contact with each other, for example, a spacer may be disposed between the diffusing member and the sealing material sheet. The gap may be an air layer.

[0197] When the first layer of the diffusion material is placed directly on one side of the sealing material sheet, the first layer of the diffusion material can be formed directly on one side of the sealing material sheet, for example, by a printing method or resin shaping using a mold.

[0198] 2. Encapsulating sheet The encapsulant sheet in the present disclosure is a member used for encapsulating LED elements and made of an encapsulant composition containing a thermoplastic resin.

[0199] The encapsulant sheet has optical transparency. Note that the term "optical transparency" and "transparency" in the encapsulant sheet refers to transparency to the extent that it does not impede visibility of light from the LED elements.

[0200] (1) Materials for the encapsulant sheet The encapsulant sheet in the present disclosure is composed of an encapsulant composition containing a thermoplastic resin.

[0201] The thermoplastic resin used in the encapsulant sheet of the present disclosure is usually a resin that does not substantially generate components that deteriorate the LED substrate (deterioration components). Here, "resin that does not substantially generate deteriorating components" refers to a resin that does not contain deteriorating components itself, or that contains deteriorating components to an extent that does not affect the deterioration of the LED substrate, or a resin that does not generate deteriorating components during the manufacture and use of the LED backlight, or that generates deteriorating components to an extent that does not affect the deterioration of the LED substrate, even if they do.

[0202] An example of a resin that generates such degradation components is ethylene-vinyl acetate copolymer (EVA), which generates acid components as degradation components.

[0203] In addition, the thermoplastic resin used in the present disclosure is preferably one that has a melt viscosity that, when heated, enables it to conform to the unevenness of the LED elements and other components arranged on one side of the LED substrate and to penetrate into gaps.

[0204] Specifically, the melt mass flow rate (MFR) of the thermoplastic resin used is preferably 0.5 g / 10 min to 40 g / 10 min, more preferably 2.0 g / 10 min to 40 g / 10 min. By having the MFR in the above range, it becomes possible for the resin to penetrate into the gaps between the LED elements, to exhibit sufficient sealing performance, and to provide a sealing member with excellent adhesion to the LED substrate.

[0205] In this specification, MFR refers to the value measured at 190°C under a load of 2.16 kg according to JIS K7210. However, for polypropylene resin, MFR refers to the MFR value measured at 230°C under a load of 2.16 kg according to JIS K7210.

[0206] When the encapsulant sheet is a multilayer member as described below, the MFR is measured by the above-mentioned measurement method while all layers are in a multilayer state in which they are laminated together, and the measured value obtained is regarded as the MFR value of the multilayer encapsulant.

[0207] The melting point of the thermoplastic resin used in the present disclosure is not particularly limited as long as it can encapsulate the LED element in a temperature range that does not deteriorate the LED substrate, but is preferably, for example, 55° C. or higher and 135° C. or lower. The melting point of the thermoplastic resin can be measured, for example, by differential scanning calorimetry (DSC) in accordance with the method for measuring the transition temperature of plastics (JISK7121).

[0208] In the present disclosure, examples of the thermoplastic resin that can be used include olefin-based resins, ionomer-based resins, and polyvinyl butyral-based resins.

[0209] Among them, the thermoplastic resin is preferably an olefin resin. This is because the olefin resin is particularly unlikely to produce components that deteriorate the LED substrate and has a low melt viscosity, so that the LED element can be well sealed. Among the olefin resins, a polyethylene resin or a polypropylene resin is preferable.

[0210] Here, the polyethylene resin in this specification includes not only ordinary polyethylene obtained by polymerizing ethylene, but also resins obtained by polymerizing a compound having an ethylenically unsaturated bond such as an α-olefin, resins obtained by copolymerizing a plurality of different compounds having an ethylenically unsaturated bond, and modified resins obtained by grafting another chemical species onto these resins.

[0211] Among them, a silane copolymer (hereinafter also referred to as "silane copolymer") obtained by copolymerizing an α-olefin and an ethylenically unsaturated silane compound as a comonomer can be preferably used. This is because the use of such a resin can provide higher adhesion between the LED substrate and the sealing member. The silane copolymer can be one described in JP 2018-50027 A.

[0212] (2) Structure of the encapsulant sheet The encapsulant sheet in the present disclosure may be a single-layer member in which the encapsulant sheet 21a is composed of a single resin layer, as shown in FIG. 12, or may be a multilayer member in which the encapsulant sheet 21a is composed of multiple resin layers (three layers in FIG. 16) stacked together, as shown in FIG. 16.

[0213] In the case of the multilayer member, it is possible to use a material that is usually expensive but has good adhesion and molding properties that allow it to enter gaps between LED elements, etc., for the layer located on the opposite side of the diffusion member in the multilayer member, i.e., the layer located on the LED substrate side. The multilayer member may have a two-layer structure, but is preferably a three-layer structure in which layers with good adhesion are arranged on both sides.

[0214] In the above multilayer member, the material constituting the layer located on the opposite side to the diffusion member side, i.e., the layer located on the LED substrate side, is not particularly limited as long as it has high adhesion and molding properties, but in the case of the above thermoplastic resin, it is preferable to use, for example, the above-mentioned silane copolymer, etc. In addition, in the case of the above thermoplastic resin, it is also preferable that the above material contains the above olefin resin and a silane coupling agent.

[0215] The thickness of the encapsulant sheet can be appropriately selected according to the layer structure of the LED substrate, and is not particularly limited. The thickness of the encapsulant sheet may be, for example, 100 μm or more, 250 μm or more, or 300 μm or more. The thickness of the encapsulant sheet may be, for example, 600 μm or less, or 550 μm or less. If the thickness is too thin, the function as a encapsulant may not be fully exhibited, or uneven brightness may occur. On the other hand, if the thickness is too thick, it may be difficult to reduce the thickness and weight, or the light transmittance may be adversely affected.

[0216] Furthermore, when the encapsulant sheet is a three-layered member, the thickness of the central layer of the three layers may be, for example, 60 μm or more, 100 μm or more, 250 μm or more, or 400 μm or less, or 350 μm or less. In this case, the thickness of each of the outer layers of the three layers may be, for example, 15 μm or more and 200 μm or less.

[0217] In this specification, the "thickness" can be measured using a known measurement method capable of measuring sizes on the order of μ, and as an example, it can be measured using images observed with an optical microscope or a scanning electron microscope (SEM). The same applies to measurements of sizes such as "size".

[0218] (3)Other The encapsulant composition used in the encapsulant sheet may contain a thermoplastic resin, and may contain other additives such as a crosslinking agent, a silane coupling agent, an antioxidant, a light stabilizer, etc. as necessary. The molding method of the encapsulant sheet may be the same as the molding method of a general resin sheet. An example of the molding method may be a T-die method, but is not limited thereto.

[0219] (4) Specific embodiment of the encapsulant sheet As described above, the encapsulant sheet contains a thermoplastic resin, more preferably contains an olefin-based resin, and further preferably contains a polyethylene-based resin. 3 More than 0.930g / cm 3 It is preferable to use the following polyethylene resin as the base resin, because such an encapsulant sheet has good adhesion to the LED substrate and good conformability to members arranged on the LED substrate.

[0220] A suitable encapsulant sheet will now be described in detail.

[0221] The sealing material sheet has a density of 0.870 g / cm 3More than 0.930g / cm 3 The resin film has the following polyethylene resin as a base resin: That is, the above-mentioned encapsulant sheet is an encapsulant sheet having the above-mentioned polyethylene resin as a base resin.

[0222] The sealing material sheet is preferably a multilayer film composed of a plurality of layers including a core layer and skin layers disposed on both outermost surfaces. In this case, the core layer has a density of 0.910 g / cm 3 More than 0.930g / cm 3 The following polyethylene resin is preferably used as the base resin, and the skin layer has a density of 0.890 g / cm 3 More than 0.910g / cm 3 It is preferable to use a polyethylene-based resin having a density of 0.1 to 100 nm or less and a lower density than the base resin for the core layer as the base resin.

[0223] In the case of the multilayer film, the total thickness is, for example, preferably 100 μm or more, more preferably 250 μm or more, and even more preferably 300 μm or more. The total thickness is, for example, preferably 600 μm or less, and more preferably 550 μm or less. If the total thickness is too thin, it is not possible to sufficiently cushion the impact, but if the total thickness is within the above range, it is possible to achieve both molding properties and heat resistance at a sufficiently preferable level. If the total thickness is too thick, it is difficult to obtain any further improvement in the impact cushioning effect, it is not possible to meet the demand for a thinner film, and it is uneconomical.

[0224] The thickness of the core layer in the multilayer film is, for example, preferably 60 μm or more, more preferably 100 μm or more, and even more preferably 250 μm or more. The thickness of the core layer is, for example, preferably 400 μm or less, more preferably 350 μm or less. In this case, the thickness of each layer of the skin layer can be, for example, 15 μm or more, may be 30 μm or more, and can be 200 μm or less. By setting the thickness of each layer within such a range, the heat resistance and molding properties of the encapsulant sheet can be maintained within a good range.

[0225] The encapsulant sheet is prepared by molding an encapsulant composition, which will be described in detail below, into a sheet shape by a conventionally known method.

[0226] When the above-mentioned encapsulant sheet is formed into an encapsulating member, the encapsulant composition used in the production of each layer has a composition having a different density range or the like as a base resin for each layer.

[0227] In this case, the encapsulant composition for the core layer and the encapsulant composition for the skin layer are used for forming each layer. Then, by forming a multilayer film having a predetermined thickness and a three-layer structure in which skin layers are arranged on both outermost surfaces using each of the encapsulant compositions for the core layer and the skin layer, it is possible to produce an encapsulant sheet 21a having a three-layer structure of a skin layer 22a, a core layer 23, and a skin layer 22b, as shown in Fig. 16, for example.

[0228] As the base resin of the encapsulant composition for the core layer of the encapsulant sheet, a low-density polyethylene resin (LDPE), a linear low-density polyethylene resin (LLDPE), or a metallocene linear low-density polyethylene resin (M-LLDPE) can be preferably used. Among these, from the viewpoint of long-term reliability, low-density polyethylene resin (LDPE) can be particularly preferably used as the composition for the core layer.

[0229] The density of the polyethylene resin used as the base resin of the encapsulant composition for the core layer is 0.910 g / cm 3 More than 0.930g / cm 3 More preferably, it is 0.920 g / cm 3 By setting the density of the base resin of the encapsulant composition for the core layer in the above range, the encapsulant sheet can be provided with necessary and sufficient heat resistance without undergoing a crosslinking treatment.

[0230] The melting point of the encapsulant composition for the core layer is preferably 90°C or more and 135°C or less, and more preferably 100°C or more and 115°C or less. By setting the melting point of the core layer within the above melting point range, the heat resistance and molding properties of these encapsulant compositions can be maintained within a preferred range. It is possible to increase the melting point of the encapsulant composition to about 135°C by adding a high melting point resin such as polypropylene to the encapsulant composition for the core layer. In this case, the polypropylene is preferably contained in an amount of 5% by mass or more and 40% by mass or less with respect to the total resin components of the core layer.

[0231] The polypropylene contained in the core layer is preferably a homopolypropylene (homoPP) resin. HomoPP is a polymer consisting of only polypropylene alone and has high crystallinity, so it has higher rigidity than block PP or random PP. By using it as an additive resin to the encapsulant composition for the core layer, the dimensional stability of the encapsulating member can be improved. In addition, the homoPP used as an additive resin to the encapsulant composition for the core layer preferably has an MFR of 5 g / 10 min or more and 125 g / 10 min or less at 230 ° C. and a load of 2.16 kg measured in accordance with JIS K7210. If the MFR is too small, the molecular weight becomes large and the rigidity becomes too high, making it difficult to ensure the desired sufficient flexibility of the encapsulant composition. In addition, if the MFR is too large, the fluidity during heating is not sufficiently suppressed, and the encapsulant sheet cannot be provided with sufficient heat resistance and dimensional stability.

[0232] The melt mass flow rate (MFR) of the polyethylene resin used as the base resin of the encapsulant composition for the core layer is preferably 2.0 g / 10 min or more and 7.5 g / 10 min or less, more preferably 3.0 g / 10 min or more and 6.0 g / 10 min or less, at 190° C. and a load of 2.16 kg. By setting the MFR of the base resin of the encapsulant composition for the core layer within the above range, the heat resistance and molding properties of the encapsulating member can be maintained within a preferred range. In addition, the processability during film formation can be sufficiently improved, which contributes to improving the productivity of the encapsulating member.

[0233] The content of the base resin in the encapsulant composition for the core layer relative to the total resin components is 70% by mass or more and 99% by mass or less, and preferably 90% by mass or more and 99% by mass or less. As long as the base resin is contained within the above range, other resins may be contained.

[0234] As the base resin of the encapsulant composition for the skin layer of the encapsulant sheet, a low-density polyethylene resin (LDPE), a linear low-density polyethylene resin (LLDPE), or a metallocene linear low-density polyethylene resin (M-LLDPE) can be preferably used, as in the encapsulant composition for the core layer. Among them, from the viewpoint of molding properties, a metallocene linear low-density polyethylene resin (M-LLDPE) can be particularly preferably used as the encapsulant composition for the skin layer.

[0235] The density of the polyethylene resin used as the base resin of the encapsulant composition for the skin layer is 0.890 g / cm 3 More than 0.910g / cm 3 More preferably, 0.899 g / cm 3 By setting the density of the base resin of the encapsulant composition for the skin layer within the above range, the adhesion of the encapsulating member can be maintained within a preferred range.

[0236] The melting point of the encapsulant composition for the skin layer is preferably from 55° C. to 100° C., and more preferably from 80° C. to 95° C. By setting the melting point of the encapsulant composition for the skin layer within the above range, the adhesion of the encapsulating member can be further reliably improved.

[0237] The melt mass flow rate (MFR) of the polyethylene resin used as the base resin of the encapsulant composition for the skin layer is preferably 2.0 g / 10 min or more and 7.0 g / 10 min or less, more preferably 2.5 g / 10 min or more and 6.0 g / 10 min or less, at 190° C. and a load of 2.16 kg. By setting the MFR of the base resin of the encapsulant composition for the skin layer within the above range, the adhesion of the encapsulant sheet can be more reliably maintained within a preferred range. In addition, the processability during film formation can be sufficiently improved, contributing to improving the productivity of the encapsulant sheet.

[0238] The content of the base resin relative to the total resin components in the encapsulant composition for the skin layer is from 60% by mass to 99% by mass, and preferably from 90% by mass to 99% by mass. As long as the base resin is contained within the above range, other resins may be contained.

[0239] It is more preferable that all the above-described encapsulant compositions contain a certain amount of a silane copolymer obtained by copolymerizing an α-olefin and an ethylenically unsaturated silane compound as a comonomer, if necessary. Such a graft copolymer increases the degree of freedom of the silanol group that contributes to the adhesive force, and therefore can improve the adhesiveness of the encapsulant sheet to other members.

[0240] The silane copolymer can be, for example, the silane copolymer described in JP-A-2003-46105. By using the silane copolymer as a component of the encapsulant composition, it is possible to obtain an encapsulant sheet that is excellent in strength, durability, and other properties, and is also excellent in weather resistance, heat resistance, water resistance, light resistance, and other properties, and further has extremely excellent heat fusion properties without being affected by production conditions such as heat and pressure bonding when arranging the encapsulant sheet, and can be obtained stably and at low cost.

[0241] As the silane copolymer, any of random copolymer, alternating copolymer, block copolymer and graft copolymer can be preferably used, but graft copolymer is more preferable, and graft copolymer having polyethylene for polymerization as main chain and ethylenically unsaturated silane compound as side chain is further preferable. Such graft copolymer has high degree of freedom of silanol group that contributes to adhesive force, and can improve adhesiveness of sealing material sheet.

[0242] The content of the ethylenically unsaturated silane compound when forming the copolymer of α-olefin and ethylenically unsaturated silane compound is, for example, 0.001% by mass to 15% by mass, preferably 0.01% by mass to 5% by mass, particularly preferably 0.05% by mass to 2% by mass. When the content of the ethylenically unsaturated silane compound constituting the copolymer of α-olefin and ethylenically unsaturated silane compound is high, the mechanical strength and heat resistance are excellent, but when the content is excessive, the tensile elongation and heat fusion adhesion tend to be poor.

[0243] The content of the silane copolymer in the total resin components of the encapsulant composition is preferably 2% by mass or more and 20% by mass or less in the encapsulant composition for the core layer, and 5% by mass or more and 40% by mass or less in the encapsulant composition for the skin layer. In particular, it is more preferable that the encapsulant composition for the skin layer contains 10% by mass or more of the silane copolymer. The amount of silane modification in the silane copolymer is preferably about 1.0% by mass or more and 3.0% by mass or less. The preferred content range of the silane copolymer in the encapsulant composition is based on the premise that the amount of silane modification is within this range, and it is desirable to finely adjust it appropriately according to the variation of the amount of modification.

[0244] All the sealing material compositions may also be appropriately added with an adhesion improver. The addition of the adhesion improver can improve the adhesion durability with other members. As the adhesion improver, a known silane coupling agent can be used, but a silane coupling agent having an epoxy group or a silane coupling agent having a mercapto group is particularly preferably used.

[0245] 3. Wavelength conversion materials In the laminate of the present disclosure, for example, as shown in Fig. 17(a), a wavelength conversion member 41 may be disposed on the surface side of the second layer 3 of the diffusing member 1, or as shown in Fig. 17(b), a wavelength conversion member 41 may be disposed between the diffusing member 1 and the sealing material sheet 21a. The wavelength conversion member may be the same as the wavelength conversion member described in the above section "A. Diffusing member".

[0246] 4.Optical components In the laminate of the present disclosure, for example, as shown in Fig. 17(b), an optical member 42 may be disposed on the surface of the diffusing member 1 facing the second layer 3. The optical member may be the same as the optical member described in the above section "A. Diffusing member".

[0247] 5. Other configurations In the laminate of the present disclosure, for example, as shown in FIG. 15(a), when a low refractive index layer 43 is disposed between the first layer 2 of the diffusion member 1 and the sealing material sheet 21a, the low refractive index layer is a layer having a refractive index lower than that of the first layer of the diffusion member. The refractive index of the low refractive index layer is lower than that of the first layer of the diffusion member, so that total reflection can be suppressed. In addition, as described above, the laminate of this embodiment uses the surface on the sealing material sheet side as the light incidence surface of the LED element, and when the first layer of the diffusion member is, for example, a transmission type diffraction grating or a microlens array, a low refractive index layer having a refractive index different from that of the first layer is disposed on the light incidence side of the first layer of the diffusion member, so that the light can be diffracted by the transmission type diffraction grating or refracted by the microlens array.

[0248] The refractive index of the low refractive index layer may be lower than that of the first layer of the diffusing member, and may be, for example, 1.0 to 1.5. The refractive index difference between the low refractive index layer and the first layer of the diffusing member is preferably large, and may be, for example, 0.3 to 1.0. The large refractive index difference between the low refractive index layer and the first layer of the diffusing member can increase the refraction angle when the first layer is, for example, a microlens array or a diffusing agent-containing resin film, and can increase the diffraction angle when the first layer is, for example, a transmission diffraction grating.

[0249] The low refractive index layer may contain, for example, a resin and low refractive index particles, or may contain a fluorine-containing resin. When the low refractive index layer contains a resin and low refractive index particles, the low refractive index particles may be, for example, inorganic particles or organic particles. The low refractive index particles may be hollow particles. The resin may be, for example, a curable resin.

[0250] II. Second embodiment of the laminate A second embodiment of the laminate in the present disclosure is a member including a transmission type diffraction grating or a microlens array, a diffusion member having a dielectric multilayer film, and an encapsulant sheet arranged on the surface of the diffusion member facing the transmission type diffraction grating or the microlens array and used to encapsulate an LED element, the encapsulant sheet being made of an encapsulant composition containing a thermoplastic resin. When the laminate of this embodiment is used, the surface facing the encapsulant sheet is used as the light incidence surface of the LED element.

[0251] The second embodiment of the laminate in the present disclosure can achieve the same effects as the first embodiment of the laminate described above.

[0252] The diffusion member in this embodiment is the same as that described in the above section "A. Diffusion member II. Second embodiment."

[0253] The arrangement of the diffusing member and the sealing material sheet may be such that, for example, a transmission type diffraction grating or a microlens array is arranged directly or via an adhesive layer or a pressure-sensitive adhesive layer on one side of the dielectric multilayer film of the diffusing member, and a sealing material sheet is arranged via a low refractive index layer on the side of the diffusing member facing the transmission type diffraction grating or microlens array; the transmission type diffraction grating or microlens array of the diffusing member may be arranged directly on one side of the sealing material sheet, and a gap may be arranged between the dielectric multilayer film of the diffusing member and the transmission type diffraction grating or microlens array; or the transmission type diffraction grating or microlens array may be arranged directly on one side of the dielectric multilayer film of the diffusing member, and a gap may be arranged between the diffusing member and the sealing material sheet.

[0254] The configuration in the case where a gap is arranged between the transmission type diffraction grating or microlens array of the diffusing member and the dielectric multilayer film can be the same as the case where a gap is arranged between the first layer and the second layer of the diffusing member in the first embodiment of the laminate described above. Also, the configuration in the case where a gap is arranged between the diffusing member and the sealing material sheet can be the same as the case where a gap is arranged between the diffusing member and the sealing material sheet in the first embodiment of the laminate described above.

[0255] When a transmission type diffraction grating or a microlens array of a diffusion member is directly disposed on one surface of the encapsulant sheet, the transmission type diffraction grating or the microlens array of the diffusion member can be directly formed on one surface of the encapsulant sheet, for example, by a printing method or resin shaping using a mold.

[0256] The encapsulant sheet in this embodiment can be the same as the encapsulant sheet in the first embodiment of the laminate described above.

[0257] The low refractive index layer in this embodiment can be the same as the low refractive index layer in the first embodiment of the laminate described above.

[0258] In the laminate in this embodiment, a wavelength conversion member may be disposed on the surface of the diffusing member facing the dielectric multilayer film, or the wavelength conversion member may be disposed between the diffusing member and the sealing material sheet. The wavelength conversion member may be the same as the wavelength conversion member described in the above section "A. Diffusing member".

[0259] In the laminate of this embodiment, an optical member may be disposed on the surface of the diffusing member facing the dielectric multilayer film. The optical member may be the same as the optical member described in the above section "A. Diffusing member."

[0260] C. Installing the diffusion material The set of diffusion members in the present disclosure comprises a first member having a first layer and a sealing material sheet used for sealing an LED element, and a second member having a second layer and arranged on the surface of the first member facing the first layer with a gap therebetween, wherein the first layer has light transparency and light diffusivity, the second layer has a reflectance that increases as the absolute value of the incident angle of light with respect to the surface of the second layer facing the first layer decreases and a transmittance that increases as the absolute value of the incident angle of light with respect to the surface of the second layer facing the first layer increases, and the sealing material sheet is composed of a sealing material composition containing a thermoplastic resin.

[0261] As shown in Fig. 18, a set 60 of diffusion members includes a first member 61 having a first layer 2 and an encapsulant sheet 21a used to encapsulate an LED element, and a second member 62 having a second layer 3. The second member 62 is used by being disposed on the surface of the first member 61 on the first layer 2 side with a gap therebetween. The first layer 2 has optical transparency and optical diffusion properties. In addition, the second layer 3 has incident angle dependency of reflectance and incident angle dependency of transmittance.

[0262] The set of diffusion members according to the present disclosure can achieve the same effects as the laminate described above.

[0263] The first member and the second member are separate members, and by arranging the first member and the second member with a gap therebetween, the first member and the second member can be used as a diffusion member.

[0264] The first layer and the second layer in the present disclosure are the same as the first layer and the second layer described above in the section "A. Diffusion member."

[0265] The encapsulant sheet in the present disclosure is the same as the encapsulant sheet described in the above section "B. Laminate."

[0266] In the first member, a wavelength conversion member may be disposed between the first layer and the encapsulant sheet. Meanwhile, in the second member, a wavelength conversion member may be disposed on one surface of the second layer. Also, in the second member, an optical member may be disposed on one surface of the second layer. The wavelength conversion member and the optical member may be the same as the wavelength conversion member and the optical member described in the above section "A. Diffusion member".

[0267] D. LED backlight The LED backlight of the present disclosure has two embodiments, each of which will be described below.

[0268] I. First embodiment of LED backlight The first embodiment of the LED backlight of the present disclosure is a device comprising: an LED substrate on one side of a support substrate on which a plurality of LED elements are arranged; and a diffusion member arranged on the LED substrate on the side of the LED elements, the diffusion member having a first layer and a second layer in this order from the LED substrate side, the first layer having optical transparency and optical diffusion properties, the second layer having a reflectance that increases as the absolute value of the incident angle of light on the surface of the second layer on the first layer side decreases, and a transmittance that increases as the absolute value of the incident angle of light on the surface of the second layer on the first layer side increases. The LED backlight of the present disclosure is a direct type LED backlight.

[0269] Fig. 2 is a schematic cross-sectional view showing an example of an LED backlight of the present disclosure. Note that Fig. 2 has been described above in the section "A. Diffusion member," so description thereof will be omitted here.

[0270] FIG. 19 is a schematic cross-sectional view showing another example of the LED backlight of the present disclosure. As illustrated in FIG. 19, the LED backlight 10 includes an LED substrate 11 having a plurality of LED elements 13 arranged on one side of a support substrate 12, a sealing member 21 arranged on the LED substrate 11's surface side on the LED substrate 11 side to seal the LED elements 13, and a diffusing member 1 arranged on the opposite surface side of the sealing member 21 to the LED substrate 11 side, having a first layer 2 and a second layer 3 in this order from the sealing member 21 side. The first layer 2 in the diffusing member 1 has optical transparency and optical diffusion properties, and transmits and diffuses light L1, L2, and L2' incident from the surface 2A opposite to the surface on the second layer 3 side of the first layer 2. The reflectance of the second layer 3 in the diffusing member 1 increases as the absolute value of the incident angle of light to the surface 3A on the first layer 2 side of the second layer 3 decreases, and the transmittance increases as the absolute value of the incident angle of light to the surface 3A on the first layer 2 side of the second layer 3 increases. Therefore, in the second layer 3, the light L1 incident at a low incident angle θ1 on the surface 3A of the second layer 3 on the first layer 2 side is reflected, and the light L1 incident at high incident angles θ2 and θ 2’ 19 shows an example in which the reflective layer 15 is disposed on the surface of the LED substrate 11 on which the LED elements 13 of the support substrate 12 are disposed, except for the LED element mounting area on which the LED elements 13 are mounted.

[0271] 19, light emitted from LED element 13 and incident on surface 1A of diffusion member 1 on the first layer 2 side is diffused by first layer 2, and light L1 that is incident on surface 3A of second layer 3 on the first layer 2 side at a low incident angle θ1 from light that has been diffused through first layer 2 is reflected by surface 3A of second layer 3 on the first layer 2 side and is then allowed to again enter first layer 2 and be diffused. Then, light L1 that is incident on surface 3A of second layer 3 on the first layer 2 side at a high incident angle θ2, θ 2’ The light L2 and L2' incident at this position can be transmitted through the second layer 3 and emitted from the surface 1B of the diffusing member 1 on the second layer 3 side.

[0272] In the present disclosure, by having the above-mentioned diffusing member, it is possible to improve the in-plane uniformity of luminance and to reduce the thickness. In addition, it is also possible to reduce costs and power consumption. In addition, since the distance between the LED element and the diffusing member can be shortened, the thickness of the sealing member can be reduced, and weight can be reduced. In addition, by using the above-mentioned diffusing member, the LED backlight of the present disclosure can be easily manufactured.

[0273] A first embodiment of the LED backlight of the present disclosure will now be described.

[0274] 1. Diffusion material The diffusion member in the present disclosure is a member that is disposed on the surface of the LED substrate facing the LED elements, and has, in order from the LED substrate side, a first layer and a second layer, the first layer having optical transparency and optical diffusion properties, and the second layer having an increased reflectance as the absolute value of the incident angle of light with respect to the surface of the second layer facing the first layer becomes smaller, and an increased transmittance as the absolute value of the incident angle of light with respect to the surface of the second layer facing the first layer becomes larger.

[0275] The diffusion member in this disclosure is the same as the member described in the above section "A. Diffusion member." Each member constituting the diffusion member can be the same as the content described in the above section "A. Diffusion member," so the description here is omitted.

[0276] The diffusion member is disposed at a predetermined distance from the light emitting surface of the LED element of the LED board. The distance between the diffusion member and the light emitting surface of the LED element of the LED board is preferably 5 mm or less, more preferably 2 mm or less, and particularly preferably 1 mm or less. If the distance is within the above range, the device can be made thin. The lower limit of the distance is not particularly limited.

[0277] Here, the distance between the diffusing member and the light-emitting surface of the LED element on the LED substrate is, for example, the distance d between the surface 1A on the first layer 2 side of the diffusing member 1 and the light-emitting surface of the LED element 13 on the LED substrate 11 as shown in FIG. 2.

[0278] 2. LED board The LED substrate in the present disclosure is a member in which a plurality of LED elements are arranged on one surface side of a support substrate.

[0279] The LED substrate will be described below.

[0280] (1) LED element In the LED backlight of the present disclosure, the LED elements function as a light source.

[0281] The LED backlight of the present disclosure can be a white LED. The LED element is not particularly limited as long as it can irradiate white light when used as an LED backlight, and can be, for example, an LED element that can emit white light, blue light, ultraviolet light, infrared light, or the like.

[0282] The LED element can be a chip-shaped LED element. The form of the LED element can be, for example, a light-emitting part (also called an LED chip) itself, or a packaged LED (also called a chip LED) such as a surface-mount type or a chip-on-board type. The packaged LED can have, for example, a light-emitting part and a protective part that covers the light-emitting part and contains a resin. Specifically, when the LED element is the light-emitting part itself, the LED element can be, for example, a blue LED element, an ultraviolet LED element, or an infrared LED element. When the LED element is a packaged LED, the LED element can be, for example, a white LED element.

[0283] When the LED backlight of the present disclosure is a combination of an LED element and a wavelength conversion member to irradiate white light, the LED element is preferably a blue LED element, an ultraviolet LED element, or an infrared LED element. The blue LED element can be combined with, for example, a yellow phosphor, or a red phosphor and a green phosphor to generate white light. The ultraviolet LED element can be combined with, for example, a red phosphor, a green phosphor, and a blue phosphor to generate white light. Among them, it is preferable that the LED element is a blue LED element. This is because the LED backlight of the present disclosure can irradiate white light with high brightness.

[0284] In addition, when the LED element is a white LED element, the white LED element is appropriately selected according to the light emission method of the white LED element. Examples of the light emission method of the white LED element include a combination of a red LED, a green LED, and a blue LED, a combination of a blue LED, a red phosphor, and a green phosphor, a combination of a blue LED and a yellow phosphor, and a combination of an ultraviolet LED, a red phosphor, a green phosphor, and a blue phosphor. Therefore, the white LED element may have, for example, a red LED light emitting part, a green LED light emitting part, and a blue LED light emitting part, a blue LED light emitting part and a protective part containing a red phosphor and a green phosphor, a blue LED light emitting part and a protective part containing a yellow phosphor, or an ultraviolet LED light emitting part and a protective part containing a red phosphor, a green phosphor, and a blue phosphor. Among them, it is preferable that the white LED element has a blue LED light emitting part and a protective part containing a red phosphor and a green phosphor, a blue LED light emitting part and a protective part containing a yellow phosphor, or an ultraviolet LED light emitting part and a protective part containing a red phosphor, a green phosphor, and a blue phosphor. Among these, it is preferable that the white LED element has a blue LED light emitting part and a protective part containing red and green phosphors, or has a blue LED light emitting part and a protective part containing yellow phosphors, because the LED backlight of the present disclosure can irradiate white light with high brightness.

[0285] The structure of the LED element can be the same as that of a general LED element.

[0286] The LED elements are usually arranged at equal intervals on one side of the support substrate. The arrangement of the LED elements is appropriately selected depending on the application and size of the LED backlight of the present disclosure, the size of the LED elements, etc. The arrangement density of the LED elements is also appropriately selected depending on the application and size of the LED backlight of the present disclosure, the size of the LED elements, etc.

[0287] The size (chip size) of the LED element is not particularly limited, and can be a general chip size. The size of the LED element may be a chip size called a mini LED or a micro LED. In particular, when a sealing member is arranged, the chip size called a mini LED is preferable. Specifically, the size of the LED element may be several hundred micrometers square, or several tens of micrometers square. More specifically, the size of the LED element can be 100 μm square or more and 300 μm square or less. When the size of the LED element is small, the LED elements can be arranged at high density, that is, the interval (pitch) between the LED elements can be reduced. Therefore, even if the distance between the LED substrate and the diffusion member is shortened, the brightness unevenness can be suppressed. Therefore, further thinning is possible. In addition, the distance between the LED substrate and the diffusion member can be shortened, that is, the thickness of the sealing member can be reduced, and weight can be reduced.

[0288] (2) Support substrate The supporting substrate in the present disclosure is a member that supports the above-mentioned LED elements and the like.

[0289] The supporting substrate may be transparent or opaque. The supporting substrate may be flexible or rigid. The material of the supporting substrate may be an organic material, an inorganic material, or a composite material in which both an organic material and an inorganic material are combined.

[0290] When the material of the support substrate is an organic material, a resin substrate can be used as the support substrate. On the other hand, when the material of the support substrate is an inorganic material, a ceramic substrate or a glass substrate can be used as the support substrate. When the material of the support substrate is a composite material, a glass epoxy substrate can be used as the support substrate. In addition, for example, a metal core substrate can be used as the support substrate. A printed circuit board on which a circuit is formed by printing can also be used as the support substrate.

[0291] The thickness of the supporting substrate is not particularly limited, and is appropriately selected depending on the presence or absence of flexibility or rigidity, and the application and size of the LED backlight of the present disclosure.

[0292] (3)Other The LED substrate in the present disclosure is not particularly limited as long as it has the above-mentioned support substrate and LED element, and can have a necessary configuration as appropriate. Such configurations can include, for example, a wiring portion, a terminal portion, an insulating layer, a reflective layer, a heat dissipation member, etc. Each configuration can be the same as that used in a known LED substrate.

[0293] The wiring portion is electrically connected to the LED element. The wiring portion is usually arranged in a pattern. The wiring portion can be arranged on a support substrate via an adhesive layer. For example, a metal material or a conductive polymer material can be used as the material of the wiring portion.

[0294] The wiring portion is electrically connected to the LED element by a joint portion, which may be made of a material such as a solder or adhesive containing a conductive material such as a metal or a conductive polymer.

[0295] A reflective layer can be disposed on the surface of the support substrate on which the LED elements are disposed, in an area other than the LED element mounting area. The light reflected by the second layer of the diffusing member can be reflected by the reflective layer of the LED substrate and can be made to enter the first layer of the diffusing member again, thereby improving the light utilization efficiency.

[0296] The reflective layer can be the same as the reflective layer generally used in the LED substrate. Specifically, the reflective layer can be a white resin film containing metal particles, inorganic particles or pigment and resin, a metal film, a porous film, etc. The thickness of the reflective layer is not particularly limited as long as it can obtain a desired reflectance, and can be appropriately set.

[0297] The LED substrate can be formed by a known method.

[0298] 3. Other materials In the LED backlight of the present disclosure, the space between the LED substrate and the diffusing member may be a space as shown in FIG. 2, or sealing members 21 and 14 that seal the LED elements may be disposed as shown in FIGS. 19 and 20.

[0299] When there is a space between the LED substrate and the diffusing member, a spacer can be disposed between the LED substrate and the diffusing member. The spacer can be the same as the spacer used in a general LED backlight.

[0300] In addition, as described above, when the size of the LED elements is small, the LED elements can be arranged at high density, i.e., the interval (pitch) between the LED elements can be made small, so that uneven brightness can be suppressed even if the distance between the LED substrate and the diffusion member is short. In this way, when the distance between the LED substrate and the diffusion member is short, a sealing member can be arranged between the LED substrate and the diffusion member.

[0301] (1) Sealing member The sealing member in the present disclosure is a member that is disposed on the LED element side of the LED substrate and seals the LED elements. The sealing member has optical transparency and is disposed on the light-emitting surface side of the LED substrate.

[0302] The term "light transmissive" and "transparent" in the sealing member refers to a material that is transparent to the extent that it does not impede visibility of light from the LED element.

[0303] The material contained in the sealing member in the present disclosure is not particularly limited as long as it is a material that can seal the LED element, and examples thereof include thermosetting resins, photocurable resins, thermoplastic resins, and the like.

[0304] Among these, thermoplastic resins are preferred. The reason why thermoplastic resins are preferred is described above in the section "B. Laminate", so a detailed description thereof will be omitted here. explain.

[0305] The thermoplastic resin used in the sealing member in the present disclosure is the same as the thermoplastic resin described in the above section "B. Laminate 2. Sealing material sheet."

[0306] As the thermosetting resin used in the sealing member in the present disclosure, any thermosetting resin generally used in sealing members for LED backlights can be used, such as silicone-based resins and epoxy-based resins.

[0307] As the photocurable resin used in the sealing member in the present disclosure, a photocurable resin generally used in the sealing member of an LED backlight can be adopted.

[0308] The sealing member in the present disclosure may be a single-layer member in which sealing member 21 is composed of a single resin layer, as shown in Fig. 19, or may be a multi-layer member in which sealing member 21 is laminated with a plurality of resin layers (three layers in Fig. 21) as shown in Fig. 21. For example, as shown in Fig. 21, sealing member 21 may have a three-layer structure of skin layer 22a, core layer 23, and skin layer 22b.

[0309] The structure of the sealing member may be the same as that of the sealing material sheet in the laminate.

[0310] In the present disclosure, the sealing member is preferably a member formed using a sealing material sheet composed of a sealing material composition containing a thermoplastic resin. The sealing material composition may be the same as the sealing material composition used in the sealing material sheet in the laminate.

[0311] Details of the sealing member can be the same as those described in the above section "B. Laminate 2. Sealing material sheet."

[0312] The thickness of the sealing member is appropriately set depending on the distance between the above-mentioned diffusion member and the light emitting surface of the LED element of the LED substrate.

[0313] (2) Wavelength conversion material The wavelength conversion member is usually disposed on the light emitting surface side of the LED substrate, and is disposed closer to the viewer than the LED elements. In the LED backlight of the present disclosure, the wavelength conversion member may be disposed on the first layer side or the second layer side of the diffusing member. In addition, when a sealing member is disposed, the wavelength conversion member may be disposed, for example, as shown in FIG. 22(a), such that the wavelength conversion member 41 is disposed on the second layer 3 side of the diffusing member 1, or as shown in FIG. 22(b), such that the wavelength conversion member 41 is disposed between the diffusing member 1 and the sealing member 21. The wavelength conversion member may be the same as the wavelength conversion member described in the above section "A. Diffusing member".

[0314] (3) Optical components In the LED backlight of the present disclosure, an optical member may be disposed on the second layer side of the diffusing member. The optical member may be the same as the optical member described in the above section "A. Diffusing member."

[0315] II. Second embodiment of LED backlight The second embodiment of the LED backlight of the present disclosure is a device including an LED substrate on one side of a support substrate on which a plurality of LED elements are arranged, and a diffusing member arranged on the LED substrate on the side of the LED elements, the diffusing member having, in order from the LED substrate side, a transmission type diffraction grating or a microlens array and a dielectric multilayer film. The LED backlight of this embodiment is a direct type LED backlight.

[0316] The LED backlight of this embodiment can achieve the same effects as the LED backlight of the first embodiment described above.

[0317] The diffusion member in this embodiment is the same as the member described in the above section "A. Diffusion member II. Second embodiment." Each member constituting the diffusion member can be the same as the content described in the above section "A. Diffusion member II. Second embodiment," so the description here is omitted.

[0318] The distance between the diffusion member and the light emitting surface of the LED elements of the LED substrate can be the same as in the first embodiment of the LED backlight described above.

[0319] The LED substrate in this embodiment can be the same as the LED substrate in the first embodiment of the LED backlight described above.

[0320] Other members in this embodiment can be similar to the other members in the above-mentioned first embodiment of the LED backlight.

[0321] D.Display device The display device of the present disclosure is a device including a display panel and the above-mentioned LED backlight disposed on the rear surface of the display panel.

[0322] 23 and 24 are schematic diagrams showing an example of a display device of the present disclosure. As shown in Fig. 23 and 24, a display device 30 or 50 includes a display panel 31 or 51 and an LED backlight 10 disposed on the back surface of the display panel 31 or 51.

[0323] According to the present disclosure, by using the above-mentioned LED backlight, it is possible to improve the in-plane uniformity of luminance while achieving a thinner display. It is also possible to reduce costs and power consumption. Therefore, a high-quality display device can be obtained.

[0324] Hereinafter, each component of the display device of the present disclosure will be described.

[0325] 1. LED backlight The LED backlight in this disclosure is the same as the components described in the above section "C. LED backlight." The components constituting the LED backlight can be the same as those described in the above section "C. LED backlight," so the description here is omitted.

[0326] 2. Display panel The display panel in the present disclosure is not particularly limited, and examples thereof include a liquid crystal panel.

[0327] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present disclosure and exhibits similar effects is included in the technical scope of the present disclosure. EXAMPLES

[0328] The present disclosure will be described in more detail below with reference to examples.

[0329] An optical simulation was performed to evaluate the in-plane uniformity of luminance. The simulation was performed by ray tracing using LightTools made by Synopsys.

[0330] [Test Example 1] (conditions) Configuration: A diffusion material is placed above the LED board. Diffusion material: A diffusion material in which a first layer having optical transparency and optical diffusion properties and a second layer having incident angle dependence of reflectance and transmittance are laminated. Thickness of diffusion material: 0.2mm Diffusion element size: 4mm Distance from the surface of the LED board to the diffusion material: 0.5mm Light transmittance of the first layer of the diffusion material: Total light transmittance 98% -Light diffusion properties of the first layer of the diffusion material: refracts incident light at 45° Dependence of reflectance and transmittance of the second layer of the diffusing material on the angle of incidence: see Figure 25 The simulation results are shown in FIG.

[0331] [Test Example 2] (conditions) Configuration: A diffusion plate is placed above the LED board. Diffusion material: Diffusion plate containing particles Light transmittance and light diffusion of the diffuser: Total light transmittance 95%, Haze 85% Thickness of diffusion material: 0.5mm Diffusion element size: 4mm Distance from the surface of the LED board to the diffusion material: 0.2mm The simulation results are shown in FIG.

[0332] [Test Example 3] (conditions) Configuration: A transparent reflector and a diffusing member are arranged in this order above the LED board. Diffuser: A diffuser containing particles Light transmittance and light diffusion of the diffuser: Total light transmittance 95%, Haze 85% ·Transmissive reflector: A through hole was drilled into Furukawa Electric's ultra-fine foam light reflector "MCPET" (0.5mm thick) to create a transmissive reflector. The through hole was designed so that the diameter of the through hole located directly above the LED element was 0.25mm, and the diameter of the through hole increased the further away from the LED element in the surface direction (see Figure 28). Thickness of the reflector: 0.5mm Diffuser thickness: 2.4mm Size of diffuser and reflector: 24mm Distance from the surface of the LED board to the transmissive reflector: 3.1mm The simulation results are shown in FIG.

[0333] [Test Example 4] (conditions) Configuration: Optical components are placed above the LED board Optical component: an optical component having only a second layer having a reflectance and a transmittance that depend on an incident angle Optical material (second layer) thickness: 0.05mm - Size of optical component (second layer): 4mm Distance from the surface of the LED board to the optical components: 0.5mm Dependence of reflectance and transmittance of the optical component (second layer) on the angle of incidence: See Figure 25 The simulation results are shown in FIG.

[0334] [evaluation] As a result of the above simulation, the in-plane uniformity of illuminance was improved in Test Example 1. On the other hand, in Test Example 2, the illuminance was non-uniform, even though the distance between the LED substrate and the diffusing member was shorter than in Test Example 1. From this result, it was confirmed that by using the configuration of the diffusing member of the present disclosure, it is possible to improve the in-plane uniformity of luminance while reducing the thickness.

[0335] Moreover, in Test Example 3, the in-plane uniformity of illuminance was excellent, but the distance between the LED substrate and the transflector was longer than in Test Example 1. Test Examples 2 and 3 show that when a conventional diffusion plate or transflector is used, the distance between the LED substrate and the diffusion plate or transflector must be increased in order to achieve uniform brightness. From these results, it was confirmed that when a sealing member is disposed between the LED substrate and the diffusion member or diffusion plate or transflector, the diffusion member configuration of the present disclosure can improve the in-plane uniformity of brightness while making the device thinner and lighter.

[0336] Moreover, in Test Example 1, the diameter of the white portion in the illuminance distribution was larger than that in Test Example 4. From this result, it was confirmed that the in-plane uniformity of luminance is improved by using the configuration of the diffusing member of the present disclosure. [Explanation of symbols]

[0337] 1 … Diffusion material 2 … 1st layer 3…Second layer 10 … LED backlight 11 ... LED board 12 ... Support substrate 13 ... LED element 14, 21... Sealing member 21a ... Encapsulating material sheet 15 … reflective layer 30, 50 … Display device 31, 51 … Display panel 40 ... Laminate 60 ... Diffusion element installation 61 … First member 62 … Second member

Claims

1. an LED backlight including an LED board having a support board and an LED element disposed on one surface side of the support board, and a diffusing member; and a sealing material sheet disposed between the LED board and the diffusing member and used to seal the LED element; a first layer disposed on one surface side of the encapsulant sheet and having light transmitting and light diffusing properties; the first layer is disposed in a pattern on one surface of the sealing material sheet, the encapsulant sheet is made of an encapsulant composition containing an olefin-based resin, a second layer is disposed on a surface of the first layer opposite to the sealing material sheet; The second layer is a layer in which the reflectance increases as the absolute value of the incident angle of light with respect to the surface of the second layer facing the first layer decreases, and the transmittance increases as the absolute value of the incident angle of light with respect to the surface of the second layer facing the first layer increases.

2. The laminated member according to claim 1 , wherein the first layer is a diffusing agent-containing resin film having a resin and a diffusing agent contained in the resin.

3. The laminated member of claim 2 , wherein the light is red light.

4. The laminated member of claim 2 , wherein the light is green light.

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