JP2022071213A - Diffusion member, laminate, diffusion member set, led backlight, and display device - Google Patents

Abstract

SOLUTION: This disclosure provides a diffusion member which is formed by laminating a transmission grating or a micro-lens array and a dielectric multilayer film, where the dielectric multilayer film has 80% or more and less than 100% regular reflectance of visible light which is incident on a surface on a side of the transmission grating or a micro-lens array of the dielectric multilayer film at 0° incident angle.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2022,JPO&INPIT

Description

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

In recent years, display devices using an LED backlight as a light source, such as a liquid crystal display device, have rapidly become widespread.

Here, the LED backlight is roughly classified into a direct type method and an edge light type method. In small and medium-sized display devices such as mobile terminals such as smartphones, an edge light type LED backlight is usually used, but from the viewpoint of brightness and the like, a direct type LED backlight may be used. It is being considered. On the other hand, in a large display device such as a large-screen liquid crystal television, a direct-type LED backlight is often used.

The direct type LED backlight has a configuration in which a plurality of LED elements are arranged on a substrate. In such a direct-type LED backlight, by independently controlling a plurality of LED elements, so-called local dimming is realized in which the brightness of each area of the LED backlight is adjusted according to the brightness of the displayed image. be able to. This makes it possible to significantly improve the contrast and reduce the power consumption of the display device.

In the direct type LED backlight, a diffuser plate is arranged above the LED element from the viewpoint of suppressing uneven brightness.

Japanese Unexamined Patent Publication No. 2018-67441 JP-A-2017-92021 Japanese Patent No. 5062408 Japanese Unexamined Patent Publication No. 2019-61954

However, in the direct type LED backlight, it is necessary to arrange the LED element and the diffuser separately from each other in order to suppress the uneven brightness. Therefore, it is difficult to make it thinner. In particular, when the number of LED elements is reduced in order to reduce cost and power consumption, uneven brightness is likely to occur because the arrangement interval of the LED elements is widened. In this case, since it is necessary to increase the distance between the LED element and the diffuser plate, it becomes more difficult to reduce the thickness. Therefore, the conventional direct-type LED backlight has a problem that it is difficult to achieve uniform brightness and thinning at the same time.

Further, in order to improve the in-plane uniformity of luminance, it has been proposed to further arrange a transmission reflector between the LED element and the diffuser (see, for example, Patent Document 1). The transmissive reflector has a patterned reflective portion and a transmissive portion. More specifically, the transmissive portion is directly above the LED element, and the transmissive portion gradually increases from directly above the LED element toward the periphery. Has a pattern like. As a result, the light directly above the LED element can be reflected and diffused to the surroundings and emitted from the surrounding transmitting portion, and the in-plane uniformity of the brightness can be improved.

However, even when such a transmissive reflector is used, it is difficult to reduce the thickness because it is necessary to dispose the LED element and the transmissive reflector separately in order to suppress the uneven luminance. Further, since the transmissive reflector has a patterned reflective portion and a transmissive portion and the reflective portion is arranged directly above the LED element, it is necessary to align the LED element and the transmissive reflector.

Further, in order to make the brightness uniform and thin, for example, in Patent Document 2, a half mirror that reflects a part of the incident light and transmits a part of the incident light is arranged between the LED element and the diffusing plate. As a half mirror, it has been proposed to use a half mirror having a lower reflectance than a vertical incident.

Further, in order to make the brightness uniform, for example, in Patent Document 3, the light from the light source is transmitted and diffracted between the LED element and the diffuser, and the transmitted diffracted light larger than 0 emitted to the center of the optical axis is transmitted and diffracted. It has been proposed to arrange a diffractive optical element for a backlight that emits transmitted diffracted light with an annular intensity distribution in which the intensity of transmitted diffracted light emitted to the peripheral portion is stronger than the intensity.

The present disclosure has been made in view of the above circumstances, and is a diffusion member, a laminate, a set of diffusion members, an LED backlight and a display capable of reducing the thickness while improving the in-plane uniformity of brightness. The main purpose is to provide the device.

As a result of diligent studies to solve the above problems, the present inventors have combined a layer having light transmittance and light diffusivity and a layer having an incident angle dependence of reflectance and transmittance as a diffusion member. By using it, it has been found that it is possible to reduce the thickness while improving the in-plane uniformity of brightness, and the present invention has been completed.

That is, one embodiment of the present disclosure is a diffusion member having a first layer and a second layer in this order, and the first layer has light transmittance and light diffusivity, and the second layer. The transmittance of the layer 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 the incident angle of light on the surface of the second layer on the first layer side increases. Provided is a diffusion member in which the transmittance increases as the absolute value of is increased.

Another embodiment of the present disclosure provides a diffusing member having a transmissive diffraction grating or a microlens array and a dielectric multilayer film.

Another embodiment of the present disclosure comprises the above-mentioned diffusion member and a sealing material sheet arranged on the surface side of the first-layer side of the above-mentioned diffusion member and used for sealing the LED element. The encapsulant sheet provides a laminate composed of an encapsulant composition containing a thermoplastic resin.

Other embodiments of the present disclosure include the above-mentioned diffusion member and a sealing material sheet which is arranged on the surface side of the transmission type diffraction grating or the microlens array side of the above-mentioned diffusion member and is used for sealing the LED element. , And the encapsulant sheet provides a laminate composed of an encapsulant composition containing a thermoplastic resin.

Another embodiment of the present disclosure has a first member having a first layer and a sealing material sheet used for sealing an LED element, and a second layer, which is the above-mentioned first member. The surface on the first layer side is provided with a second member that is arranged and used via a gap portion, the first layer has light transmittance and light diffusivity, and the second layer is the second layer. The reflectance increases as the absolute value of the incident angle of light with respect to the surface on the first layer side decreases, and as the absolute value of the incident angle of light with respect to the surface on the first layer side of the second layer increases. The transmittance is increased, and the encapsulant sheet provides a set of diffusing members composed of an encapsulant composition containing a thermoplastic resin.

In another embodiment of the present disclosure, an LED substrate in which a plurality of LED elements are arranged on one surface side of the support substrate and an LED substrate arranged on the surface side of the LED substrate on the LED element side are arranged in order from the LED substrate side. A diffusion member having a first layer and a second layer is provided, the first layer has light transmission and light diffusivity, and the second layer is a surface of the second layer on the first layer side. The reflectance increases as the absolute value of the incident angle of light with respect to the LED decreases, and the transmissivity increases as the absolute value of the incident angle of light with respect to the surface of the second layer on the first layer side increases. Provide lights.

Another embodiment of the present disclosure includes an LED substrate in which a plurality of LED elements are arranged on one surface side of the support substrate, and a diffusion member arranged on the surface side of the LED substrate on the LED element side. The diffusion member provides an LED backlight having a transmission type diffraction grid or a microlens array and a dielectric multilayer film in order from the LED substrate side.

The present disclosure provides a display device comprising a display panel and the above-mentioned LED backlight arranged on the back surface of the display panel.

The present disclosure has an effect that it is possible to provide a diffusion member, an LED backlight, and a display device capable of reducing the thickness while improving the in-plane uniformity of luminance.

It is a schematic sectional drawing illustrating the diffusion member of this disclosure. It is a schematic sectional drawing illustrating the LED backlight of this disclosure. It is a figure explaining the diffusion angle. It is a figure explaining the light diffusivity in this disclosure. It is a figure explaining the light diffusivity in this disclosure. It is a schematic cross-sectional view which illustrates the transmission type diffraction grating in this disclosure. It is a schematic sectional drawing illustrating the diffusion member in this disclosure. It is a schematic plan view and a sectional view illustrating the reflection structure in this disclosure. It is a schematic plan view and a sectional view illustrating the reflection structure in this disclosure. It is a schematic cross-sectional view which illustrates the reflection structure in this disclosure. It is a schematic sectional drawing illustrating the diffusion member of this disclosure. It is a schematic sectional drawing illustrating the laminated body of this disclosure. It is a process drawing which illustrates the manufacturing method of the LED backlight of this disclosure. It is a process drawing which illustrates the manufacturing method of the LED backlight of this disclosure. It is a schematic sectional drawing illustrating the laminated body of this disclosure. It is a schematic sectional drawing illustrating the laminated body of this disclosure. It is a schematic sectional drawing illustrating the laminated body of this disclosure. It is a schematic cross-sectional view illustrating the set of diffusion members in this disclosure. It is a schematic sectional drawing illustrating the LED backlight of this disclosure. It is a schematic sectional drawing illustrating the LED backlight of this disclosure. It is a schematic sectional drawing illustrating the LED backlight of this disclosure. It is a schematic sectional drawing illustrating the LED backlight of this disclosure. It is a schematic diagram which illustrates the display device of this disclosure. It is a schematic diagram which illustrates the display device of this disclosure. It is a graph which shows the incident angle dependence of the reflectance and the transmittance of the 2nd layer of the diffusion member of the test example 1. FIG. It is an optical simulation result of Test Example 1. It is an optical simulation result of Test Example 2. It is a graph which shows the relationship between the position of the through hole of the transmission reflector and the aperture ratio in Test Example 3. It is the result of the optical simulation of Test Example 3. It is the result of the optical simulation of Test Example 4.

Hereinafter, the diffusion member, the LED backlight, and the display device of the present disclosure will be described. However, the present disclosure can be implemented in many different embodiments and is not construed as being limited to the description of the embodiments exemplified below. Further, in order to clarify the explanation, the drawings may schematically represent the width, thickness, shape, etc. of each member as compared with the embodiment, but this is merely an example and the interpretation of the present disclosure. Is not limited to. Further, in the present specification and each figure, the same elements as those described above with respect to the above-mentioned figures may be designated by the same reference numerals, and detailed description thereof may be omitted as appropriate.

In the present specification, when expressing an embodiment in which another member is arranged above or below a certain member, when the term "on the surface side" is simply used, unless otherwise specified, the member is directly above the member so as to be in contact with the certain member. Alternatively, it includes both the case where another member is arranged directly below and the case where another member is arranged above or below one member via another member.

Further, in the present specification, the "LED" means a light emitting diode.
Further, in the present specification, terms such as "sheet", "film", and "board" are not distinguished from each other based only on the difference in designation. For example, "sheet" is used to include a member that is also called a film or a plate.

A. Diffusion member The diffusion member in the present disclosure has two embodiments. Hereinafter, each embodiment will be described.

I. First Embodiment of Diffusing Member The first embodiment of the diffusing member of the present disclosure is a member having a first layer and a second layer in this order, and the first layer is light transmissive and light diffusing. The second layer has a property, and the reflectance of the second layer increases as the absolute value of the incident angle of light with respect to the surface of the second layer on the first layer side decreases, and the first layer of the second layer increases. It is a member whose transmittance increases as the absolute value of the incident angle of light with respect to the side surface increases. When the diffusion member of the present disclosure is used, the surface on the first layer side is used as the incident surface of light.

Hereinafter, the first embodiment of the diffusion 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 diffusion member of the present disclosure. As illustrated in FIG. 1, the diffusion member 1 has a first layer 2 and a second layer 3 in this order. The first layer 2 has light transmission and light diffusivity, and transmits and diffuses light L1 and L2 incident from a surface 2A opposite to the surface of the first layer 2 on the second layer 3 side. Further, in the second layer 3, the reflectance increases as the absolute value of the incident angle of light with respect to the surface 3A on the first layer 2 side of the second layer 3 decreases, and the reflectance of the second layer 3 increases on the first layer 2 side of the second layer 3. The transmittance increases as the absolute value of the incident angle of light with respect to the surface 3A increases. Therefore, in the second layer 3, the light L1 incident on the surface 3A on the first layer 2 side of the second layer 3 at a low incident angle θ ₁ is reflected, and the surface on the first layer 2 side of the second layer 3 is reflected. Light L2 incident on 3A at a high incident angle θ ₂ can be transmitted. The low incident angle means that the absolute value of the incident angle is small, and the high incident angle means that the absolute value of the incident angle is large.

FIG. 2 is a schematic cross-sectional view showing an example of a direct-type LED backlight provided with the diffusion member according to the first embodiment of the present disclosure, and is an example including the diffusion member shown in FIG. As illustrated in FIG. 2, the LED backlight 10 has an LED substrate 11 in which the LED element 13 is arranged on one surface of the support substrate 12 and a diffusion arranged on the surface side of the LED substrate 11 on the LED element 13 side. It has a member 1. The diffusion member 1 is arranged so that the surface 1A on the first layer 2 side faces the LED substrate 11. In FIG. 2, the LED substrate 11 and the diffusion member 1 are arranged apart from each other.

In the present disclosure, as shown in FIG. 1, the light incident from the surface 1A on the first layer 2 side of the diffusion member 1 is diffused by the first layer 2 and the light diffused through the first layer 2. Of these, the light L1 incident on the surface 3A on the first layer 2 side of the second layer 3 at a low incident angle θ ₁ is on the first layer 2 side of the second layer 3, as shown in FIG. It can be reflected by the surface 3A and again incident on the first layer 2 to be diffused. Then, among the light transmitted through the first layer 2 and diffused, the light L2 and L2'that are incident on the surface 3A on the first layer 2 side of the second layer 3 at a high incident angle θ ₂ are the second. The layer 3 can be transmitted and emitted from the surface 1B on the second layer 3 side of the diffusion member 1. Further, by combining the first layer and the second layer, the light incident from the surface on the first layer side of the diffusion member, particularly the light incident from the surface on the first layer side of the diffusion member at a low incident angle, is measured many times. Also, since the first layer can be transmitted and diffused, it can be emitted from the surface of the diffusion member on the second layer side at a high emission angle.
Therefore, when the diffusing member of the present disclosure is used for a direct type LED backlight, the light emitted from the LED element can be diffused over the entire light emitting surface, and the in-plane uniformity of brightness can be improved. can.

Further, in the present disclosure, as described above, by combining the first layer and the second layer, the first layer is repeatedly applied to the light incident from the surface of the diffusion member on the first layer side at a low incident angle. Since the light can be transmitted, the optical path length from the light incident from the surface on the first layer side of the diffusion member to the emission from the surface on the second layer side of the diffusion member can be lengthened. As a result, a part of the light emitted from the surface of the diffusion member on the second layer side after being emitted from the LED element can be emitted from a position away from the LED element in the in-plane direction, not directly above the LED element. become able to.
Therefore, in the direct type LED backlight provided with the diffusing member of the present disclosure, it is possible to suppress the luminance unevenness even when the distance between the LED element and the diffusing member is shortened. Therefore, it is possible to reduce the thickness while improving the in-plane uniformity of the luminance. Further, even when the number of LED elements is reduced, uneven brightness can be suppressed. Therefore, it is possible to simultaneously realize uniform brightness, thinning, cost reduction, and low power consumption.

Further, unlike the conventional transmission / reflection plate, the diffusion member of the present disclosure can eliminate the need for alignment with the LED element. Therefore, the LED backlight can be easily manufactured by using the diffusion member of the present disclosure.

Hereinafter, the first embodiment of the diffusion member of the present disclosure will be described in detail.

1. 1. First Layer The first layer in the present disclosure is a member arranged on one surface side of the second layer described later and having light transmission and light diffusivity.

As the light transmittance of the first layer, for example, the total light transmittance of the first layer is preferably 50% or more, particularly 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 brightness can be increased when the diffusing member of the present disclosure is used for the LED backlight.

The total light transmittance of the first layer can be measured by, for example, a method according to JIS K7361-1: 1997. As the light source, the CIE standard light source D65 can be used.

The light diffusing property of the first layer may be, for example, a light diffusing property that randomly diffuses light, or a light diffusing property that mainly diffuses light in a specific direction. The light diffusivity that diffuses light mainly in a specific direction is a property that deflects light, that is, a property that changes the traveling direction of light. Above all, the light diffusivity of the first layer is preferably the light diffusivity that mainly diffuses light in a specific direction. By deflecting the light in a predetermined direction, that is, by controlling the traveling direction of the light, the light can be shaped into an arbitrary shape or an arbitrary intensity distribution, and the in-plane uniformity of brightness can be further improved. ..

As the light diffusivity of the first layer, when it is a light diffusing property that diffuses light randomly, for example, the diffusion angle of the light incident on the first layer can be 10 ° or more, and at 15 ° or more. It may be present, and it may be 20 ° or more. Further, the diffusion angle of the 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 brightness can be improved when the diffusion member of the present disclosure is used for the LED backlight.

Here, the diffusion angle will be described. FIG. 3 is a graph illustrating the transmitted light intensity distribution and is a diagram for explaining the diffusion angle. In the present specification, light is vertically incident on one surface of the first layer constituting the diffusion member, and is half of the maximum transmitted light intensity I _max of the light emitted from the other surface of the first layer. The full width at half maximum (FWHM), which is the difference between two angles that become 1, is defined as the diffusion angle α.

The diffusion angle can be measured using a variable angle photometer or a variable angle spectrophotometer. For the measurement of the diffusion angle, for example, a variable angle photometer (Goniophotometer) GP-200 manufactured by Murakami Color Technology Research Institute can be used.

Further, the light diffusing property of the first layer is not particularly limited as the shape and intensity distribution of the light transmitted through the first layer when the light diffusing property mainly diffuses light in a specific direction. However, it is appropriately selected according to the light distribution characteristics of the light source, the shape and intensity distribution of the target light, and the like. Examples of the light diffusivity of the first layer include the property of emitting light having a non-Gaussian-like intensity distribution, and specifically, the property of emitting light having an annular intensity distribution and the top. The property of emitting light having a hat-like intensity distribution can be mentioned. 4 (a) and 4 (b) are examples of an annular intensity distribution, and FIG. 5 is an example of a top hat-like intensity distribution.

Above all, the light diffusivity of the first layer is preferably a property of emitting light having an annular intensity distribution. In particular, the light diffusivity of the first layer is a property of emitting light having an annular intensity distribution, and as shown in FIG. 4A, for example, the intensity of transmitted light emitted to the center of the optical axis is approximately the same. It is preferably zero. The light incident from the surface on the first layer side of the diffusing member is spread in a ring shape on the first layer, and the light incident on the surface on the first layer side of the second layer at a low incident angle is the second layer. It can be reflected on the surface on the first layer side of the light, and then incident on the first layer again to spread it in an annular shape. By repeating this, the light incident from the surface of the diffusion member on the first layer side can be spread in the lateral direction.
Therefore, when the diffusing member of the present disclosure is used for a direct type LED backlight, the light emitted from the LED element can be diffused over the entire light emitting surface, and the in-plane uniformity of luminance can be further improved. At the same time, it is possible to eliminate the need for alignment with the LED element.

Here, the intensity distribution can be measured using a variable angle photometer or a variable angle spectrophotometer.

The first layer is not particularly limited as long as it has the above-mentioned light transmission and light diffusivity, and various configurations having the above-mentioned light transmission and light diffusivity can be adopted. Examples of the first layer include a transmission type diffraction grating, a microlens array, a diffusing agent-containing resin film containing a diffusing agent, and a resin. Specifically, when the first layer has a light diffusing 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 diffusing property of randomly diffusing light, a diffusing agent-containing resin film can be mentioned. Among them, a transmission type diffraction grating and a microlens array are preferable from the viewpoint of light diffusivity. The transmission type diffraction grating is also referred to as a transmission type diffraction optical element (DOE; Differential Optical Elements).

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 transmission and light diffusivity.

The transmission type diffraction grating may be, for example, either a phase type diffraction grating or an amplitude type diffraction grating. Further, the phase type diffraction grating may be, for example, either a relief type diffraction grating or a volumetric diffraction grating. Above all, the transmission type diffraction grating is preferably a relief type diffraction grating. Further, when the transmission type diffraction grating is a relief type diffraction grating, it is particularly preferable that the transmission type diffraction grating is a multi-level diffraction grating having a stepped cross-sectional shape of the groove. In general, since the pitch of the diffraction grating is small in the multi-level diffraction grating, the present disclosure that 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, or the like. FIG. 6 is an example of a multi-level diffraction grating 2a having four levels.

Further, as the transmission type diffraction grating, for example, a transmission type diffraction grating that transmits and diffracts light and emits light having a non-Gaussian-like intensity distribution can be mentioned. Examples thereof include a transmission type diffraction grating that 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-like intensity distribution. Among them, the transmission type diffraction grid is a transmission type diffraction grid that transmits and diffracts light and emits light having an annular intensity distribution, that is, transmission diffraction of light transmitted and diffracted and emitted to the center of the optical axis. It is preferable that the transmission diffractive lattice emits the transmitted diffracted light with an annular intensity distribution in which the intensity of the transmitted diffracted light emitted to the peripheral portion is stronger than the intensity. In particular, it is a transmission type diffraction grating that emits transmitted diffracted light with an annular intensity distribution and, for example, as shown in FIG. 4A, the intensity of the transmitted diffracted light emitted to the center of the optical axis is almost zero. preferable. In the case of such a transmission type diffraction grating, when the diffusion member of the present disclosure is used for the LED backlight, the intensity of the light emitted to the center of the optical axis is reduced and the intensity of the light emitted to the peripheral portion is reduced. It can be increased and the in-plane uniformity of brightness can be further improved.

In the case of a transmission type diffraction grating that transmits and diffracts light and emits light having an annular intensity distribution, in the annular intensity distribution, the direction in which the intensity of the transmitted diffraction light is maximum and the normal direction of the transmission type diffraction grating The angle formed by the 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 make the brightness uniform. Further, if the angle is too large, total reflection may occur and it may be difficult to make the brightness uniform. Further, the angle may be, for example, 30 ° or more and 45 ° or less. When the angle is within the above range, the transmission type diffraction grating can be easily manufactured.

Here, the intensity distribution and the angle can be measured using a variable-angle photometer or a variable-angle spectrophotometer. For the measurement of the above angle, for example, a variable angle photometer GP-200 manufactured by Murakami Color Technology Research Institute, a variable angle spectrophotometer GCMS-11, or the like can be used.

The pitch and the like of the transmission type diffraction grating may be adjusted as long as the above-mentioned light transmission and light diffusivity can be obtained. Specifically, when the wavelength output by the LED element is a single color such as red, green, or blue, it is possible to effectively bend the light from the LED element by setting the pitch according to each wavelength. Is.

Specifically, the pitch of the transmission type diffraction grating can be 50 μm or more and 200 μm or less. As described above, since the diffusion member of the present disclosure can eliminate the need for alignment with the LED element, it is particularly effective when the pitch of the transmission type diffraction grating is as small as the above range.

When the transmission type diffraction grating is a relief type diffraction grating, the depth of the groove of the transmission type diffraction grating can be, for example, 1 μm or more and 5 μm or less.

The pitch of the transmission type diffraction grating means, for example, in the case of a multi-level diffraction grating, the distance P between adjacent grooves as shown in FIG. Further, the groove depth of the transmission type diffraction grating means, for example, in the case of a multi-level diffraction grating, the maximum depth d1 of the groove as shown in FIG.

Here, the pitch and groove depth of the transmission type diffraction lattice are the planes of the transmission type diffraction lattice observed by a transmission electron microscope (TEM), a scanning electron microscope (SEM), or a scanning transmission electron microscope (STEM). It can be obtained from an electron micrograph or a cross-sectional micrograph of a transmission electron diffraction lattice in the thickness direction.

The material constituting the transmission type diffraction grating may be any material that can obtain the above-mentioned transmission type diffraction grating having light transmission and light diffusivity, and a material generally used for the transmission type diffraction grating shall be adopted. Can be done. For example, glass such as quartz glass, resin and the like can be mentioned.

Further, the method for forming the transmission type diffraction grating can be the same as the method for forming the general transmission type diffraction grating. When the transmission type diffraction grating is a multi-level diffraction grating, the method for forming the transmission type diffraction grating is, for example, glass such as a quartz substrate by lithography using a direct drawing method of an electron beam or a laser or lithography using a photomask. A method of processing a substrate can be mentioned, and a groove having a stepped shape can be formed on a glass substrate by repeating a lithography step and an etching step. Further, as another method for forming the transmission type diffraction grating, resin shaping by a mold can be mentioned. In this case, for example, a resin layer may be formed on one surface of the base material layer, and the resin layer may be shaped by a mold to form a groove having a stepped shape in the resin layer. A groove having a stepped shape may be formed in the resin layer by forming a resin layer on one surface and shaping the resin layer with a mold. As a method for manufacturing a mold, first, a molding mold is manufactured by a method of processing a glass substrate such as a quartz substrate by lithography using the above-mentioned direct drawing method of an electron beam or a laser or lithography using a photomask, and then the mold is manufactured. In addition, a method of producing an inversion mold using this molding mold can be mentioned, and this inversion mold can be used as a mold. Further, as a method for designing a transmission type diffraction grating, for example, an iterative Fourier transform algorithm (IFTA) can be used.

When the first layer is a microlens array, the microlens array is not particularly limited as long as it has the above-mentioned light transmission and light diffusivity.

Further, as the microlens array, for example, a microlens array that transmits and refracts light and emits light having a non-Gaussian-like intensity distribution can be mentioned. Examples thereof include a microlens array that emits light having an intensity distribution, and a microlens array that transmits and refracts light and emits light having a top hat-like intensity distribution. Among them, the microlens is a microlens array that transmits and refracts light and emits light having an annular intensity distribution, that is, compared with the intensity of transmitted and refracted light that transmits and refracts light and is emitted to the center of the optical axis. Therefore, it is preferable to use a microlens array that emits transmitted refractory light with an annular intensity distribution in which the intensity of transmitted refractory light emitted to the peripheral portion is stronger. In the case of such a microlens array, when the diffusing member of the present disclosure is used for the LED backlight, the intensity of the light emitted to the center of the optical axis is reduced and the intensity of the light emitted to the peripheral portion is increased. It is possible to further improve the in-plane uniformity of brightness.

The shape, pitch, size, etc. of the microlens may be adjusted as appropriate as long as the above-mentioned light transmission and light diffusivity can be obtained.

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, since the diffusion member of the present disclosure can eliminate the need for alignment with the LED element, it is particularly effective when the pitch of the microlens is as small as the above range. Further, the pitch of the microlens can be, for example, 0.001 mm or more.

Here, the pitch of the microlens is the planographic micrograph or microlens array of the microlens array observed by a transmission electron microscope (TEM), a scanning electron microscope (SEM) or a scanning transmission electron microscope (STEM). It can be obtained from a cross-sectional electron micrograph in the thickness direction.

As the material constituting the microlens, any material that can obtain the above-mentioned microlens having light transmission and light diffusivity may be used, and materials generally used for microlenses can be adopted. Further, the method for forming the microlens can be the same as the method for forming the general microlens.

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 diffusivity.

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 a diffusing agent generally used for a diffusing plate used for an LED backlight is used. Can be adopted. 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 is the content of the diffusing agent in the diffusing plate generally used for the LED backlight. The same can be done.

Further, the resin contained in the diffuser-containing resin film is not particularly limited as long as the diffuser can be dispersed, and a resin generally used for a diffuser plate used for an LED backlight should be adopted. Can be done.

The first layer may have a structure capable of exhibiting light diffusivity, for example, the first layer may exhibit light diffusivity in the entire layer, and exhibits light diffusivity in terms of surface. It may be a thing. Examples of the surface that exhibits light diffusivity include a relief type diffraction grating and a microlens array. On the other hand, examples of the layer that exhibits light diffusivity include a volumetric diffraction grating and a diffusing agent-containing resin film.

As 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, and the first layer may be directly arranged on one surface of the second layer via an adhesive layer or an adhesive layer. The first layer may be arranged, or as shown in FIG. 7A, the first layer 2 may be arranged on one surface of the second layer 3 via a gap portion. For example, when the first layer is one that exhibits light diffusivity on a surface, and the first layer has a structure capable of exhibiting light diffusivity on a surface facing the second layer. The first layer and the second layer are preferably arranged via the voids. When the first layer is directly arranged on one surface of the second layer, for example, as shown in FIG. 7B, the first layer 2 having a pattern on one surface of the second layer 3 May be arranged. For example, when the first layer exhibits light diffusivity on a surface, it can exhibit light diffusivity even when the first layer is arranged in a pattern.

When the first layer and the second layer are arranged through the void portion, 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 can be arranged between the first layer and the second layer. Further, the void portion can be an air layer.

As a method of laminating the first layer and the second layer, for example, a method of laminating the first layer and the second layer via an adhesive layer or an adhesive layer, or a method of directly adhering the first layer to one surface of the second layer. The method of forming and the like can be mentioned. Examples of the method for directly forming the first layer on one surface of the second layer include a printing method and resin shaping by a mold. In the case of resin shaping by a printing method or a mold, a patterned first layer can be directly formed on one surface of the second layer.

2. 2. Second layer The second layer in the present disclosure is arranged on one surface side of the first layer, and the reflectance decreases as the absolute value of the incident angle of light with respect to the surface of the second layer on the first layer side decreases. The incident angle of the reflectance increases, and the incident angle of the transmittance increases as the absolute value of the incident angle of the light with respect to the surface of the second layer on the first layer side increases. It is a member having a dependency.

The second layer has an incident angle dependence of the reflectance such that the reflectance increases as the absolute value of the incident angle of light with respect to the surface on the first layer side of the second layer decreases. That is, the reflectance of light incident on the surface on the first layer side of the second layer at a low incident angle is the reflectance of light incident on the surface on the first layer side of the second layer at a high incident angle. Will be larger than. Above all, it is preferable that the reflectance of light incident on the surface of the second layer on the first layer side at a low incident angle is large.

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

Further, the average value of the specular reflectance of visible light incident on the surface of the second layer on the first layer side within an incident angle of ± 60 ° is preferably, for example, 80% or more and 99% or less. It is preferably 90% or more and 97% or less. The average value of the specular reflectance means the average value of the specular reflectance of visible light at each incident angle. When the average value of the specular reflectance is in the above range, the in-plane uniformity of brightness can be improved when the diffusion member of the present disclosure is used for the LED backlight.

Further, the specular reflectance of visible light incident on the surface of the second layer on the first layer side at an incident angle of 0 ° (perpendicularly incident) is preferably, for example, 80% or more and less than 100%. Above all, it is 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 brightness can be improved when the diffusion member of the present disclosure is used for the LED backlight.

The term "visible light" as used herein means light having a wavelength of 380 nm or more and a wavelength of 780 nm or less. Further, the specular reflectance can be measured by using a variable angle photometer or a variable angle spectrophotometer. For the measurement of the normal reflectance, for example, a variable angle photometer GP-200 manufactured by Murakami Color Technology Research Institute, a variable angle spectrophotometer GCMS-11, or the like can be used.

Further, the total light transmittance of light incident on the surface of the second layer on the first layer side within an incident angle of ± 60 ° is preferably, for example, 10% or less, and above all, 5% or less. Is preferable, and particularly preferably 3% or less. It is preferable that the total light transmittance satisfies the above range at all the incident angles within ± 60 °. When the total light transmittance is within the above range, the specular reflectance can be within the predetermined range, and when the diffusion member of the present disclosure is used for the LED backlight, the in-plane uniformity of brightness is improved. Can be made to.

The second layer has an incident angle dependence of the transmittance such that the transmittance increases as the absolute value of the incident angle of light with respect to the surface on the first layer side of the second layer increases. That is, the transmittance of light incident on the surface on the first layer side of the second layer at a high incident angle is the transmittance of light incident on the surface on the first layer side of the second layer at a low incident angle. Will be larger than. Above all, it is preferable that the transmittance of light incident on the surface of the second layer on the first layer side at a high incident angle is large. Specifically, the total light transmittance of 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 preferably 30% or more, and more than 40%. Is preferable, and particularly preferably 50% or more. It is preferable that the total light transmittance satisfies the above range at all incident angles of 70 ° or more and less than 90 °. Further, when the absolute value of the incident angle is 70 ° or more and less than 90 °, it is preferable that the total light transmittance satisfies the above range. When the diffuser member of the present disclosure is used for the LED backlight, the in-plane uniformity of brightness can be improved when the total light transmittance is in the above range.

The total light transmittance of the second layer can be measured by a method according to JIS K7361-1: 1997, for example, using a variable-angle photometer or a variable-angle spectrophotometer. For the measurement of 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, the CIE standard light source D65 can be used.

Further, the specular 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 preferably, for example, 70% or less, particularly 60% or less. It is preferably present, and particularly preferably 50% or less. It is preferable that the specular reflectance of visible light satisfies the above range at all incident angles of 70 ° or more and less than 90 °. Further, when the absolute value of the incident angle is 70 ° or more and less than 90 °, it is preferable that the specular reflectance of visible light satisfies the above range. When the specular reflectance is within the above range, the total light transmittance can be within a predetermined range, and when the diffusing member of the present disclosure is used for an LED backlight, the in-plane uniformity of brightness is improved. Can be made to.

Further, the average value of the specular 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 preferably, for example, 70% or less, and among them, 50. % Or less, and particularly preferably 30% or less. The average value of the specular reflectance means the average value of the specular reflectance of visible light at each incident angle. When the average value of the specular reflectance is within the above range, the total light transmittance can be within a predetermined range, and when the diffusion member of the present disclosure is used for the LED backlight, the brightness is uniform in the plane. It is possible to improve the sex.

The second layer is not particularly limited as long as it has the above-mentioned reflectance and transmittance incident angle dependence, and has various configurations having the above-mentioned reflectance and transmittance incident angle dependence. Can be adopted. The second layer has, for example, a dielectric multilayer film and a patterned first reflective film and a patterned second reflective film in order from the first layer side, and has an opening of the first reflective film and a second layer. Examples thereof include a reflective structure in which the openings of the two reflective films are located so as not to overlap each other in a plan view, and the first reflective film and the second reflective film are arranged apart from each other in the thickness direction, a reflective diffraction grating, and the like.

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

(1) Dielectric multilayer film When the second layer is a dielectric multilayer film, the dielectric multilayer film may be, for example, a multilayer film of an inorganic compound in which inorganic layers having different refractive indexes are alternately laminated, or a multilayer film having a refractive index. Examples thereof include a multilayer film of a resin in which different resin layers are alternately laminated.

(Multilayer film of inorganic compound)
When the dielectric multilayer film is a multilayer film of an inorganic compound in which inorganic layers having different refractive indexes are alternately laminated, the multilayer film of the inorganic compound has the above-mentioned incident angle dependence of the reflectance and the transmittance. If so, it is not particularly limited.

Among the inorganic layers having different refractive indexes, the inorganic compound contained in the high refractive index inorganic layer has, for example, a refractive index of 1.7 or more and 1.7 or more and 2.5 or less. There may be. Examples of such an inorganic compound include titanium oxide, zirconium oxide, tantalum pentoxide, niobium pentoxide, lanthanum oxide, yttrium oxide, zinc oxide, zinc sulfide, and indium oxide as main components, and titanium oxide, tin oxide, and oxidation. Examples thereof include those containing a small amount of cerium and the like.

Further, among the inorganic layers having different refractive indexes, as the inorganic compound contained in the low refractive index inorganic layer having a low refractive index, for example, the refractive index can be 1.6 or less, and 1.2 or more and 1.6. It may be as follows. Examples of such an inorganic compound include silica, alumina, lanthanum fluoride, magnesium fluoride, sodium hexafluoride, and the like.

The number of layers of the high-refractive index inorganic layer and the low-refractive index inorganic layer may be appropriately adjusted as long as the incident angle dependence of the above-mentioned reflectance and transmittance can be obtained. Specifically, the total number of layers of the high-refractive index inorganic layer and the low-refractive index inorganic layer can be four or more. The upper limit of the total number of layers is not particularly limited, but the number of layers increases as the number of layers increases, so that the number of layers may be 24 or less, for example.

The thickness of the multilayer film of the inorganic compound may be 0.5 μm or more and 10 μm or less, as long as the above-mentioned reflectance and transmittance depending on the incident angle can be obtained.

Examples of the method for forming the multilayer film of the inorganic compound include a method of alternately laminating a high refractive index inorganic layer and a low refractive index inorganic layer by a CVD method, a sputtering method, a vacuum vapor deposition method, a wet coating method, or the like. Be done.

(Multilayer film of resin)
When the dielectric multilayer film is a resin multilayer film in which resin layers having different refractive indexes are alternately laminated, the resin multilayer film may have the above-mentioned reflectance and transmittance incident angle dependence. There is no particular limitation.

Examples of the resin constituting the resin layer include a thermoplastic resin and a thermosetting resin. Among them, a thermoplastic resin is preferable because it has good moldability.

Various additives such as antioxidants, antistatic agents, crystal nucleating agents, inorganic particles, organic particles, thickeners, heat stabilizers, lubricants, infrared absorbers, ultraviolet absorbers, and refractive index adjustments are used in the resin layer. A dope agent or the like may be added.

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, polyethylene terephthalates, polybutylene terephthalates and polypropylene terephthalates. , Polybutyl succinate, polyester resin such as polyethylene-2,6-naphthalate, polycarbonate resin, polyarylate resin, polyacetal resin, polyphenylene sulfide resin, tetrafluoroethylene resin, trifluoroethylene resin, trifluoride ethylene resin. 4, Fluorine ethylene-6 fluoride propylene copolymer, fluororesin such as vinylidene fluoride resin, acrylic resin, methacrylic resin, polyacetal resin, polyglycolic acid resin, polylactic acid resin and the like can be used. Above all, polyester is more preferable from the viewpoint of strength, heat resistance and transparency.

In the present specification, the polyester refers to a homopolyester or a copolymerized polyester which is a polycondensate of a dicarboxylic acid component skeleton and a diol component skeleton. Here, examples of the homopolyester include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, poly-1,4-cyclohexanedimethylene terephthalate, and polyethylene diphenyl rate. Among them, polyethylene terephthalate is preferable because it is inexpensive and can be used in a wide variety of applications.

Further, in the present specification, the copolymerized polyester is defined as a polycondensate composed of at least three or more components selected from the following components having a dicarboxylic acid skeleton and a component having a diol skeleton. Examples of the component having a dicarboxylic acid skeleton include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 4,4-diphenyldicarboxylic acid. Examples thereof include acids, 4,4-diphenylsulfonic dicarboxylic acid, adipic acid, sebacic acid, dimer acid, cyclohexanedicarboxylic acid and their ester derivatives. Examples of the component having a glycol skeleton include ethylene glycol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentadiol, diethylene glycol, polyalkylene glycol, and 2,2. -Bis (4-β-hydroxyethoxyphenyl) propane, isosorbate, 1,4-cyclohexanedimethanol, spiroglycol and the like can be mentioned.

Among the resin layers having different refractive indexes, the difference in the in-plane average refractive index between the high refractive index resin layer having a high refractive index and the low refractive index resin layer having a low refractive index is preferably 0.03 or more. It is preferably 0.05 or more, and 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.

Further, 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 in-plane average refractive index and the thickness direction refractive index of the low refractive index resin layer The difference between the two is preferably 0.03 or less. In this case, even if the incident angle is large, the reflectance of the reflected peak is unlikely to decrease.

The preferred combination of the high refractive index resin used for the high refractive index resin layer and the low refractive index resin used for the low refractive index resin layer is firstly the difference in SP value between the high refractive index resin and the low refractive index resin. The absolute value of is preferably 1.0 or less. When the absolute value of the difference between the SP values is in the above range, delamination 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 is a repeating unit constituting the resin. For example, when one of the resins is polyethylene terephthalate, ethylene terephthalate is the basic skeleton. Further, for example, when one of the resins is polyethylene, ethylene is the basic skeleton. When the high-refractive index resin and the low-refractive index resin are resins containing the same basic skeleton, peeling between layers is more likely to occur.

The preferred combination of the high refractive index resin used for the high refractive index resin layer and the low refractive index resin used for the low refractive index resin layer is secondly, the glass transition temperature of the high refractive index resin and the low refractive index resin. The difference is preferably 20 ° C. or lower. If the difference in the glass transition temperature is too large, the thickness uniformity when forming the laminated film of the high refractive index resin layer and the low refractive index resin layer may be poor. In addition, overstretching may occur when the laminated film is formed.

Further, it is preferable that the high refractive index resin is polyethylene terephthalate or polyethylene naphthalate, and the low refractive index resin is polyester containing spiroglycol. Here, the polyester containing spiroglycol means a copolyester in which spiroglycol is copolymerized, a homopolyester, or a polyester in which they are blended. Polyester containing spiroglycol is preferable because the difference in glass transition temperature between polyethylene terephthalate and polyethylene naphthalate is small, so that overstretching does not easily occur during molding and delamination does not easily occur. More preferably, the high refractive index resin is polyethylene terephthalate or polyethylene naphthalate, and the low refractive index resin is polyester containing spiroglycol and cyclohexanedicarboxylic acid. When the low refractive index resin is a polyester containing spiroglycol and cyclohexanedicarboxylic acid, the difference in the in-plane refractive index from polyethylene terephthalate or polyethylene naphthalate becomes large, so that high refractive index can be easily obtained. In addition, since the difference in glass transition temperature between polyethylene terephthalate and polyethylene naphthalate is small and the adhesiveness is excellent, overstretching is unlikely to occur during molding, and delamination is also difficult to occur.

It is also preferable that the high refractive index resin is polyethylene terephthalate or polyethylene naphthalate, and the low refractive index resin is polyester containing cyclohexanedimethanol. Here, the polyester containing cyclohexanedimethanol means a copolyester in which cyclohexanedimethanol is copolymerized, a homopolyester, or a polyester in which they are blended. Polyester containing cyclohexanedimethanol is preferable because the difference in glass transition temperature between polyethylene terephthalate and polyethylene naphthalate is small, so that overstretching is unlikely to occur during molding, and delamination is also difficult to occur. In this case, the low refractive index resin is more preferably an ethylene terephthalate polycondensate having a copolymerization amount of cyclohexanedimethanol of 15 mol% or more and 60 mol% or less. By doing so, while having high reflection performance, the change in optical characteristics due to heating and aging is particularly small, and peeling between layers is less likely to occur. The ethylene terephthalate polycondensate in which the copolymerization amount of cyclohexanedimethanol is within the above range adheres very strongly to polyethylene terephthalate. In addition, the cyclohexanedimethanol group has a cis isomer or a trans isomer as a geometric isomer, and also has a chair type or a boat type as a conformation isomer. In terms of rate, the change in optical characteristics due to thermal history is even less, and blurring during film formation is less likely to occur.

In the multilayer film of the above resin, it is sufficient that there is a portion having a structure in which the high refractive index resin layer and the low refractive index resin layer are alternately laminated in the thickness direction. That is, it is preferable that the order of arrangement of the high-refractive index resin layer and the low-refractive index resin layer in the thickness direction is not random, and the order of arrangement of the resin layers other than the high-refractive index resin layer and the low-refractive index resin layer is Is not particularly limited. When the multilayer film of the above resin has a high refractive index resin layer, a low refractive index resin layer, and another resin layer, the arrangement of these layers is as follows: the high refractive index resin layer is A, and the low refractive index is low. When the resin layer is B and the other resin layer is C, it is more preferable that the layers are laminated in a regular order such as A (BCA) n, A (BCBA) n, and A (BABCBA) n. Here, n is the number of repeating units, and for example, when n = 3 in A (BCA) n, it represents those stacked in the order of ABCABCABCA in the thickness direction.

Further, 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 incident angle dependence of the above-mentioned reflectance and transmittance can be obtained. Specifically, the high-refractive index resin layer and the low-refractive index resin layer can be alternately laminated with 30 or more layers, and 200 or more layers may be laminated with each other. Further, the total number of layers of the high-refractive index resin layer and the low-refractive index resin layer can be, for example, 600 or more. If the number of layers is too small, sufficient reflectance may not be obtained. Further, when the number of layers is in the above range, a desired reflectance can be easily obtained. The upper limit of the total number of laminated layers is not particularly limited, but may be 1500 layers or less in consideration of a decrease in stacking accuracy due to an increase in the size of the apparatus and an excessive number of layers.

Further, 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 thereof, and more preferably has the surface layer on both sides. Further, the thickness of the surface layer is more preferably 5 μm or more. By having the surface layer, the surface of the multilayer film of the resin can be protected.

Examples of the method for producing the above-mentioned resin multilayer film include a coextrusion method and the like. Specifically, the method for producing a laminated film described in JP-A-2008-200861 can be referred to.

Further, as the multilayer film of the above resin, a commercially available laminated film can be used, and specific examples thereof include Picasas (registered trademark) manufactured by Toray Industries, Inc. and ESR manufactured by 3M.

(2) Reflective structure The reflective structure has a patterned first reflective film and a patterned second reflective film in order from the first layer side, and has an opening of the first reflective film and a second reflective film. The openings of the above are located so as not to overlap each other in a plan view, and the first reflective film and the second reflective film are arranged apart from each other in the thickness direction.

The reflective structure has two aspects. The first aspect of the reflective structure is a transparent base material, a patterned first reflective film arranged on one surface of the transparent base material, and a patterned second surface arranged on the other side of the transparent base material. It has a reflective film, the opening of the first reflective film and the opening of the second reflective film are located so as not to overlap in a plan view, and the first reflective film and the second reflective film are arranged apart from each other in the thickness direction. Is what you are doing. Further, in the second aspect of the reflective structure, the transparent base material, the patterned convex portion arranged on one surface of the transparent base material and having light transmittance, and the surface of the convex portion on the transparent base material side are It has a patterned first reflective film arranged on the opposite surface side and a patterned second reflective film arranged in the opening of the convex portion on one surface of the transparent substrate, and has a first reflective film. The opening of the first reflective film and the opening of the second reflective film are located so as not to overlap each other in a plan view, and the first reflective film and the second reflective film are arranged apart from each other in the thickness direction. Hereinafter, each aspect will be described separately.

(First aspect of reflective structure)
The first aspect of the reflective structure in the present disclosure is a transparent substrate, a patterned first reflective film arranged on one surface of the transparent substrate, and a patterned first reflective film arranged on the other surface of the transparent substrate. The first reflective film and the second reflective film are located so that the openings of the first reflective film and the second reflective film do not overlap each other in a plan view, and the first reflective film and the second reflective film are separated from each other in the thickness direction. Is arranged. In the case of the reflective structure of this embodiment, in the diffusion member of the present disclosure, the first layer is arranged on the surface side of the reflective structure on the first reflective film side.

8 (a) and 8 (b) are schematic plan views and cross-sectional views showing an example of the reflective structure of this embodiment, and FIG. 8 (a) is seen from the surface of the reflective structure on the first reflective film side. It is a plan view, and FIG. 8 (b) is a sectional view taken along line AA of FIG. 8 (a). As shown in FIGS. 8A and 8B, the reflective structure 20 includes a transparent substrate 21, a patterned first reflective film 22 arranged on one surface of the transparent substrate 21, and a transparent group. It has a second reflective film 24 arranged on the other surface of the material 21. The opening 23 of the first reflective film 22 and the opening 25 of the second reflective film 24 are located so as not to overlap each other in a plan view. Further, the first reflective film 22 and the second reflective film 24 are arranged on both sides of the transparent base material 21, respectively, and are arranged apart from each other in the thickness direction. In FIG. 8A, the opening of the second reflective film is shown by a broken line. Further, FIG. 8C is a schematic cross-sectional view showing an example of an LED backlight provided with a diffusion member having the reflection structure of this embodiment.

In such a reflective structure, a patterned first reflective film and a second reflective film are laminated so that the openings of the first reflective film and the openings of the second reflective film do not overlap in a plan view. Since it is located, when the diffusion member having the reflective structure of this embodiment is used for the LED backlight, for example, as shown in FIG. 8 (c), the first reflective film 22 and the first reflective film 22 are directly above the LED element 13. At least one of the second reflective films 24 will always be present. Therefore, for example, as shown in FIG. 8B, the surface of the reflective structure 20 on the first reflective film 22 side, that is, the side on which the first layer (not shown) of the reflective structure 20 (second layer) is arranged. The light L11 incident on the surface 3A at a low incident angle can be reflected by the first reflecting film 22 and the second reflecting film 24. Further, since the opening of the first reflective film and the opening of the second reflective film are located so as not to overlap in a plan view, the first reflective film and the second reflective film are arranged apart from each other in the thickness direction. Light incident at a high incident angle on the surface of the reflective structure 20 on the side of the first reflective film 22, that is, the surface 3A on the side of the reflective structure 20 (second layer) on which the first layer (not shown) is arranged. L12 and L13 can be emitted from the opening 23 of the first reflective film 22 and the opening 25 of the second reflective film 24. As a result, a part of the light emitted from the surface of the diffusion member on the second layer side after being emitted from the LED element can be emitted from a position away from the LED element in the in-plane direction, not directly above the LED element. become able to. Therefore, the in-plane uniformity of luminance can be improved.

Hereinafter, the reflective structure of this embodiment will be described.

As the first reflective film and the second reflective film, a general reflective film can be used, and for example, a metal film, a dielectric multilayer film, or the like can be used. As the material of the metal film, a metal material used for a general reflective film can be adopted, and examples thereof include aluminum, gold, silver, and alloys thereof. Further, as the dielectric multilayer film, those used for general reflective films can be adopted, and for example, a multilayer film of an inorganic compound such as a multilayer film in which zirconium oxide and silicon oxide are alternately laminated can be used. Can be mentioned. The materials contained in the first reflective film and the second reflective film may be the same or different from each other.

As the pitch of the openings of the first reflective film and the second reflective film, it is sufficient that the above-mentioned reflectance and transmittance depend on the incident angle, and the LED element in the LED backlight in which the diffusion member of the present disclosure is used is used. It is appropriately set according to the light distribution characteristics, size, pitch and shape, the distance between the LED substrate and the diffuser member, and the like. The pitches of the openings of the first reflective film and the second reflective film may be the same or different from each other.

The pitch of the opening of the first reflective film may be larger than the size of the LED element, for example.
Specifically, the pitch of the opening of the first reflective film can be 0.1 mm or more and 20 mm or less.

Further, the pitch of the opening of the second reflective film is not particularly limited as long as the uneven brightness can be suppressed, but it is particularly preferable that the pitch is equal to or less than the pitch of the opening of the first reflective film. It is preferably smaller than the pitch of the opening of. Specifically, the pitch of the opening of the second reflective film can be 0.1 mm or more and 2 mm or less. By making the pitch of the opening of the second reflective film fine as described above, it is possible to make it difficult to visually recognize the pattern between the portion of the second reflective film and the portion of the opening of the second reflective film. No surface emission is possible.

The pitch of the openings of the first reflective film means, for example, the distance P1 between the centers of the openings 23 of the adjacent first reflective films 22 as shown in FIG. 8A. The pitch of the openings of the second reflective film means, for example, the distance P2 between the centers of the openings 25 of the adjacent second reflective films 24 as shown in FIG. 8A.

As the size of the openings of the first reflective film and the second reflective film, it is sufficient that the incident angle dependence of the above-mentioned reflectance and transmittance can be obtained, and the LED element in the LED backlight in which the diffusion member of the present disclosure is used. It is appropriately set according to the light distribution characteristics, size, pitch and shape of the LED substrate, the distance between the LED substrate and the diffuser member, and the like. The sizes of the openings of the first reflective film and the second reflective film may be the same or different from each other.

Regarding the size of the opening of the first reflective film, specifically, when the shape of the opening of the first reflective film is rectangular, the length of the opening of the first reflective film is 0.1 mm or more. It can be 5 mm or less.

The size of the opening of the second reflective film is not particularly limited as long as the uneven brightness can be suppressed, but the size of the opening of the first reflective film is preferably smaller than the size of the opening of the first reflective film. It is preferably smaller than the size of the opening of the 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, it is possible to make it difficult to visually recognize the pattern between the portion of the second reflective film and the portion of the opening of the second reflective film, resulting in unevenness. Surface emission without light is possible.

The size of the opening of the first reflective film is, for example, when the shape of the opening of the first reflective film is rectangular, the opening 23 of the first reflective film 22 as shown in FIG. 8A. The length x1 of. Further, the size of the opening of the second reflective film means, for example, the length x 2 of the opening 25 of the second reflective film 24 as shown in FIG. 8A.

The shape of the openings of the first reflective film and the second reflective film can be any shape such as a rectangular shape and a circular shape.

The thicknesses of the first reflective film and the second reflective film may be adjusted as appropriate as long as the incident angle dependence of the above-mentioned reflectance and transmittance can be obtained. Specifically, the thickness of the first reflective film and the second reflective film can be 0.05 μm or more and 100 μm or less.

The first reflective film and the second reflective film may be formed on the surface of the transparent base material, or may be a sheet-shaped reflective film. The method for forming the first reflective film and the second reflective film is not particularly limited as long as it can form the reflective film in a pattern on the surface of the transparent substrate, and examples thereof include a sputtering method and a vacuum vapor deposition method. .. When the first reflective film and the second reflective film are sheet-shaped reflective films, examples of the method for forming the openings include a method of forming a plurality of through holes by punching or the like. In this case, as a method for laminating the transparent substrate and the sheet-shaped reflective film, for example, a method of bonding the sheet-shaped reflective film to the transparent substrate via an adhesive layer or an adhesive layer can be used.

The transparent base material in the reflective structure of this embodiment is a member that supports the first reflective film, the second reflective film, and the like, and the first reflective film and the second reflective film are arranged apart from each other in the thickness direction. It is a member for.

The transparent substrate has light transmission. As for the light transmittance of the transparent substrate, the total 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 according to JIS K7361-1: 1997. As the light source, the CIE standard light source D65 can be used.

The material constituting the transparent substrate may be any material having the above-mentioned total light transmittance, and for example, resins such as polyethylene terephthalate, polycarbonate, acrylic, cycloolefin, polyester, polystyrene, and acrylic styrene, quartz glass, and the like. Examples include glass such as Pylex (registered trademark) and synthetic quartz.

As the thickness of the transparent base material, for example, as shown in FIG. 8B, the surface of the reflective structure 20 on the first reflective film 22 side, that is, the first layer (not shown) of the reflective structure 20 (second layer). The light L12 incident on the surface 3A on the side where) is arranged at a high incident angle can be emitted from the opening 23 of the first reflective film 22 and the opening 25 of the second reflective film 24. It is preferably set appropriately according to the pitch and size of the openings of the first reflective film and the second reflective film, the thickness of the first reflective film and the second reflective film, and the like. Specifically, the thickness of the transparent substrate can be 0.05 mm or more and 2 mm or less, and more preferably 0.1 mm or more and 0.5 mm or less.

(Second aspect of reflective structure)
The second aspect of the reflective structure in the present disclosure is a transparent base material, a patterned convex portion arranged on one surface of the transparent base material and having light transmission, and a surface of the convex portion on the transparent base material side. Has a patterned first reflective film arranged on the opposite surface side and a patterned second reflective film arranged in the opening of the convex portion on one surface of the transparent substrate, and has a first reflection. The opening of the film and the opening of the second reflective film are located so as not to overlap each other in a plan view, and the first reflective film and the second reflective film are arranged apart from each other in the thickness direction. In the case of the reflective structure of this embodiment, in the diffusion member of the present disclosure, the first layer is arranged on the surface side of the reflective structure on the first reflective film side.

9 (a) and 9 (b) are schematic plan views and cross-sectional views showing an example of the second aspect of the reflective structure in the present disclosure, and FIG. 9 (a) is the first reflective film side of the reflective structure. It is a plan view seen from the surface, and FIG. 9B is a sectional view taken along line AA of FIG. 9A. As shown in FIGS. 9A and 9B, the reflective structure 20 has a transparent base material 21 and a patterned convex portion 26 arranged on one surface of the transparent base material 21 and having light transmission. , A patterned first reflective film 22 arranged on a surface opposite to the surface of the convex portion 26 on the transparent substrate 21 side, and an opening of the convex portion 26 on one surface of the transparent substrate 21. It has a patterned second reflective film 24. The opening 23 of the first reflective film 22 and the opening 25 of the second reflective film 24 are located so as not to overlap each other in a plan view. Further, the first reflective film 22 and the second reflective film 24 are separated by the convex portion 26, and are arranged apart from each other in the thickness direction.

In such a reflective structure, a patterned first reflective film and a second reflective film are laminated so that the openings of the first reflective film and the openings of the second reflective film do not overlap in a plan view. Since it is located, when the diffusion member having the reflective structure of this embodiment is used for the LED backlight, at least one of the first reflective film and the second reflective film is always present directly above the LED element. It will be. Therefore, similarly to the first aspect, for example, as shown in FIG. 9B, the surface of the reflective structure 20 on the first reflective film 22 side, that is, the first layer of the reflective structure 20 (second layer) ( The light L11 incident on the surface 3A on the side on which (not shown) is arranged at a low incident angle can be reflected by the first reflecting film 22 and the second reflecting film 24. Further, since the opening of the first reflective film and the opening of the second reflective film are located so as not to overlap each other in a plan view, the first reflective film and the second reflective film are arranged apart from each other in the thickness direction. Light incident at a high incident angle on the surface of the reflective structure 20 on the side of the first reflective film 22, that is, the surface 3A on the side of the reflective structure 20 (second layer) on which the first layer (not shown) is arranged. L12 can be emitted from the side surface of the convex portion 26 and the opening 25 of the second reflective film 24. As a result, a part of the light emitted from the surface of the diffusion member on the second layer side after being emitted from the LED element can be emitted from a position away from the LED element in the in-plane direction, not directly above the LED element. become able to. Therefore, the in-plane uniformity of luminance can be improved.

Further, in this embodiment, since the convex portion is provided, the openings of the first reflective film and the second reflective film can be self-aligned, and the manufacturing cost can be reduced.

The material of the first reflective film and the second reflective film, the pitch of the openings of the first reflective film and the second reflective film, the size of the openings of the first reflective film and the second reflective film, the first reflective film and The shape of the opening of the second reflective film, the thickness of the first reflective film and the second reflective film, the method of forming the first reflective film and the second reflective film, and the like can be the same as those in the first aspect. ..

Further, the transparent base material can be the same as that of the first aspect.

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

The convex portion has light transmission. As for the light transmittance of the convex portion, the total 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, for example, a method according to JIS K7361-1: 1997. As the light source, the CIE standard light source D65 can be used.

The material constituting the convex portion may be any material that can form a patterned convex portion and has the above-mentioned total light transmittance, and examples thereof include a thermosetting resin and an electron beam curable resin. ..

As the height of the convex portion, for example, as shown in FIG. 9B, the surface of the reflective structure 20 on the first reflective film 22 side, that is, the first layer (not shown) of the reflective structure 20 (second layer). ) Is arranged at a height such that the light L12 incident on the surface 3A on the side where the) is arranged can be emitted from the side surface of the convex portion 26 and the opening 25 of the second reflective film 24. It is preferable, and it is appropriately set according to the pitch and size of the openings of the first reflective film and the second reflective film, the thickness of the first reflective film and the second reflective film, and the like. Specifically, the height of the convex portion can be 0.05 mm or more and 2 mm or less, and more preferably 0.1 mm or more and 0.5 mm or less.

The pitch, size, and plan-view shape of the convex portion can be the same as the pitch, size, and shape of the opening of the second reflective film.

The surface of the convex portion may be, for example, a smooth surface as shown in FIG. 9 (b) or a rough surface as shown in FIG. 10 (a). When the surface of the convex portion is a rough surface, light diffusivity can be imparted to the convex portion.

Further, the shape of the surface of the convex portion may be, for example, a flat surface as shown in FIG. 9 (b) or a curved surface as shown in FIG. 10 (b). When the surface of the convex portion is a curved surface, light diffusivity can be imparted to the convex portion.

The method for forming the convex portion is not particularly limited as long as it is a method capable of forming the convex portion in the pattern, and examples thereof include a printing method and resin shaping by a mold.

(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 reflectance and transmittance depending on the incident angle.

The pitch and the like of the reflection type diffraction grating may be adjusted as appropriate as long as the incident angle dependence of the reflectance and the transmittance described above can be obtained. Specifically, when the wavelength output by the LED element is a single color such as red, green, or blue, it is possible to effectively reflect the light of the LED element by setting the pitch according to each wavelength. Is.

The material constituting the reflection type diffraction grating may be any material as long as it can obtain the above-mentioned reflection type diffraction grating having the incident angle dependence of the reflectance and the transmittance, and the material generally used for the reflection type diffraction grating is used. Can be adopted. Further, the method for forming the reflection type diffraction grating can be the same as the method for forming the general reflection type diffraction grating.

3. 3. Diffusion member In this embodiment, the thickness of the entire diffusion member can be, for example, 30 μm or more and 200 μm or less.

4. Wavelength conversion member In the diffusion member of the present disclosure, for example, as shown in FIG. 11A, the wavelength conversion member 4 is arranged on the surface side of the second layer 3 opposite to the surface on the first layer 2 side. Also, as shown in FIG. 11B, the wavelength conversion member 4 may be arranged on the surface side of the first layer 2 opposite to the surface on the second layer 3 side. In the LED backlight, a wavelength conversion member may be used for widening the color gamut, etc., and when the diffusion member of the present disclosure is used for the LED backlight, the wavelength conversion member may be combined with the diffusion member. ..

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

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 single wavelength conversion layer or a laminated body having a wavelength conversion layer on one surface side of the transparent substrate. Above all, the wavelength conversion layer alone is preferable from the viewpoint of thinning. More preferably, a sheet-shaped wavelength conversion member is used.

The fluorescent substance can be appropriately selected depending on the color emitted from the LED element, and examples thereof include a blue fluorescent substance, a green fluorescent substance, a red fluorescent substance, and a yellow fluorescent substance. For example, when the LED element is a blue LED element, as the phosphor, a green phosphor and a red phosphor may be used, or a yellow phosphor may be used. Further, for example, when the LED element is an ultraviolet LED element, a red phosphor, a green phosphor, and a blue phosphor can be used as the phosphor.

As the phosphor, a phosphor generally used for a wavelength conversion member of an LED backlight can be adopted. In addition, quantum dots can also be used as a phosphor.

The content of the phosphor in the wavelength conversion member layer is not particularly limited as long as it can generate desired white light when the diffuser member of the present disclosure is used for the LED backlight, and is general. It can be the same as the content of the phosphor in the wavelength conversion member of the LED backlight.

Further, the resin contained in the wavelength conversion member is not particularly limited as long as the phosphor can be dispersed. The resin can be the same as the resin used for the wavelength conversion member of a general LED backlight, and examples thereof include thermosetting resins such as silicone-based resins and epoxy-based resins.

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

As a method of laminating the wavelength conversion member on the first layer or the second layer, for example, a method of laminating the wavelength conversion member to the first layer or the second layer via an adhesive layer or an adhesive layer, or a first layer or a first layer. Examples thereof include a method of directly forming a wavelength conversion member on the surface of two layers. As a method of directly forming the wavelength conversion member on the surface of the first layer or the second layer, for example, a printing method can be mentioned.

5. Optical member In the diffusion member of the present disclosure, for example, as shown in FIG. 11B, even if the optical member 5 is further arranged on the surface side of the second layer 3 opposite to the surface on the first layer 2 side. good. In the LED backlight, an optical member may be used in addition to the diffusion member, and when the diffusion member of the present disclosure is used for the LED backlight, the diffusion member may be combined with the optical member. Examples of the optical member include a prism sheet, a reflective polarizing sheet, and the like.

(1) Prism sheet The prism sheet in the present disclosure has a function of condensing incident light and intensively improving the brightness in the front direction. The prism sheet is, for example, a prism sheet in which a prism pattern containing an acrylic resin or the like is arranged on one surface side of a transparent resin base material.

As the prism sheet, for example, a luminance increasing film BEF series manufactured by 3M can be used.

(2) Reflective Polarizing Sheet The reflective polarizing sheet in the present disclosure transmits only the first linear polarizing component (for example, P-polarized light) and has a second linear polarizing component (for example) orthogonal to the first linear polarizing component. For example, it has a function of reflecting S-polarized light without absorbing it. The second linear polarization component reflected by the reflective polarizing sheet is reflected again, and in a state where the polarization is eliminated (a state in which both the first linear polarization component and the second linear polarization component are included), the second linear polarization component is reflected again. It is incident on the reflective polarizing sheet. Therefore, the reflective polarizing sheet transmits the first linearly polarized light component of the light incident again, and the second linearly polarized light component orthogonal to the first linearly polarized light component is reflected again. Hereinafter, by repeating the same process, about 70% to 80% of the light emitted from the second layer is emitted as light having become the first linearly polarized light component. Therefore, when the LED backlight provided with the diffusion member of the present disclosure is used in the display device, the polarization direction of the first linear polarization component (transmission axis component) of the reflective polarizing sheet and the transmission axis direction of the polarizing plate of the display panel By matching, all 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 in the case where the reflective polarizing sheet is not arranged.

Examples of the reflective polarizing sheet include the DBEF series of luminance increasing films manufactured by 3M. Further, as the reflective polarizing sheet, for example, a high-intensity polarizing sheet WRPS manufactured by Shinwha Intertek, a wire grid polarizing element, or the like can be used.

6. Applications The diffusion member of the present disclosure is suitably used for a direct type LED backlight.

II. Second Embodiment of Diffusing Member The second embodiment of the diffusion member in 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 incident surface of light.

In the second embodiment of the diffusion member in the present disclosure, the same effect as that of the first embodiment of the above-mentioned diffusion member can be obtained by combining the transmission type diffraction grating or the microlens array with the dielectric multilayer film. ..

The transmission type diffraction grating and microlens array in this embodiment can be the same as the transmission type diffraction grating and microlens array used for the first layer in the first embodiment of the above-mentioned diffusion member.

Further, the dielectric multilayer film in this embodiment can be the same as the dielectric multilayer film used for the second layer in the first embodiment of the above-mentioned diffusion member.

The transmission type diffraction grating and the microlens array may have a structure capable of exhibiting light diffusivity, for example, may exhibit light diffusivity in the entire layer, and may exhibit light on the surface. It may be one that exhibits diffusivity.

As the arrangement of the transmission diffractive lattice or the microlens array and the dielectric multilayer film, for example, the transmission diffractive lattice or the microlens array is arranged on one surface of the dielectric multilayer film via an adhesive layer or an adhesive layer. Alternatively, a transmission diffractive lattice or a microlens array may be arranged on one surface of the dielectric multilayer film via a gap, and a transmission diffractive lattice or a microlens may be arranged on one surface of the dielectric multilayer film. The array may be placed directly.

When the transmission type diffraction grating or microlens array and the dielectric multilayer film are arranged through the gap, the transmission type diffraction grating or microlens array and the dielectric multilayer film may or may not be in contact with each other. You may. When the transmission type diffraction grating or microlens array is not in contact with the dielectric multilayer film, for example, a spacer may be arranged between the transmission type diffraction grating or microlens array and the dielectric multilayer film. Further, the void portion can be an air layer.

When the transmission type diffraction grating or the microlens array is directly arranged on one surface of the dielectric multilayer film, for example, one of the dielectric multilayer films may be formed by a printing method or resin shaping by a mold. A transmissive diffraction grating or microlens array can be formed directly on the surface.

The thickness of the entire diffusion member of the present embodiment can be the same as the thickness of the entire diffusion member of the first embodiment described above.

In the diffusion member of the present embodiment, the wavelength conversion member may be arranged on the surface opposite to the surface of the dielectric multilayer film on the transmission type diffraction grating or the microlens array side, and the transmission type diffraction grating or the microlens may be arranged. The wavelength conversion member may be arranged on the surface side opposite to the surface on the dielectric multilayer film side of the array. The wavelength conversion member may be the same as the wavelength conversion member described in the section of the first embodiment of the above-mentioned diffusion member.

In the diffusion member of the present embodiment, the optical member may be arranged on the surface side opposite to the surface on the transmission type diffraction grating or the microlens array side of the dielectric multilayer film. The optical member may be the same as the optical member described in the section of the first embodiment of the above-mentioned diffusion member.

The diffusion member of this embodiment is suitably used for a direct type LED backlight.

B. Laminates The laminates in the present disclosure have two embodiments. Hereinafter, each embodiment will be described.

I. First Embodiment of the Laminated Body The first embodiment of the laminated body of the present disclosure is arranged on a diffusion member having a first layer and a second layer in this order and a surface side of the diffusion member on the first layer side. The first layer has light transmittance and light diffusivity, and the second layer is the first layer of the second layer. The reflectance increases as the absolute value of the incident angle of light with respect to the surface on the first layer side decreases, and the transmittance increases as the absolute value of the incident angle of light with respect to the surface on the first layer side of the second layer increases. The encapsulant sheet becomes larger and is a member composed of an encapsulant composition containing a thermoplastic resin. When the laminate of the present disclosure is used, the surface on the sealing material sheet side is used as the incident surface of the light of the LED element.

FIG. 12 is a schematic cross-sectional view showing an example of the first embodiment of the laminated body of the present disclosure. As illustrated in FIG. 12, the laminated body 40 is arranged on the surface side of the diffusion member 1 having the first layer 2 and the second layer 3 in this order and the diffusion member 1 on the first layer 2 side, and is an LED element. The sealing material sheet 21a used for sealing is provided. The first layer 2 of the diffusing member 1 has light transmission and light diffusivity. The reflectance of the second layer 3 of the diffusion member 1 increases as the absolute value of the incident angle of light with respect to the surface of the second layer 3 on the first layer 2 side decreases, and the reflectance increases on the first layer 2 side of the second layer 3. The transmittance increases as the absolute value of the incident angle of light with respect to the surface increases. The encapsulant sheet 21a is composed of an encapsulant composition containing a thermoplastic resin.

Here, the direct type LED backlight is disadvantageous as compared with the edge light type, particularly in terms of thinning and weight reduction. However, as described above, it is difficult to reduce the thickness of the direct type LED backlight.

By the way, in recent years, research and development on miniaturization and high density of LED elements have been promoted, and LEDs having a small chip size, so-called mini LEDs and micro LEDs, are attracting attention. Then, it is being studied to put into practical use a technique for miniaturizing and increasing the density of LED elements as an LED backlight (see, for example, Patent Document 4).

In the direct type LED backlight, the brightness unevenness depends on the distance between the LED element and the diffuser plate and the distance between the LED elements (hereinafter, may be referred to as pitch). Therefore, it is possible to suppress the uneven brightness by shortening the distance between the LED elements.
That is, by arranging the fine LED elements at a high density, the in-plane uniformity of the brightness can be improved. In this case, it is possible to reduce the thickness.

Here, in the LED backlight, a spacer is arranged to maintain a predetermined distance between the LED element and the diffuser plate. However, the light emitted from the LED element is blocked or reflected by the spacer, which may cause uneven brightness. Further, although it is necessary to provide a large number of spacers, it is difficult to arrange a large number of spacers when the pitch is fine, for example, a mini LED or a micro LED.

Therefore, in the LED backlight, a configuration is also proposed in which a sealing member for sealing the LED element is arranged between the LED element and the diffuser plate (see, for example, Patent Document 4). However, the configuration in which the sealing member is arranged between the LED element and the diffuser plate is heavier than the configuration in which the space between the LED element and the diffuser plate is a space.

In recent years, there has been a demand for thinning and weight reduction of display devices, and further thinning and weight reduction of backlights incorporated in display devices are also required. As described above, the direct type LED backlight is disadvantageous in terms of thinning and weight reduction as compared with the edge light type, and therefore further improvement is required.

According to the present disclosure, by having the above-mentioned diffusion member, it is possible to reduce the thickness while improving the in-plane uniformity of luminance. Further, since the distance between the LED element and the diffusion member can be shortened, the thickness of the encapsulant sheet can be reduced, and the weight can be reduced.

Further, in the present disclosure, the encapsulant sheet is composed of an encapsulant composition containing a thermoplastic resin. Hereinafter, the reason why the thermoplastic resin is preferable will be described.

When the sealing member contains a thermoplastic resin in the LED backlight, a sheet-shaped sealing material composed of a sealing material composition containing the thermoplastic resin (hereinafter, may be referred to as a sealing material sheet). There is.) Can be used. 13 (a) to 13 (b) are process diagrams showing an example of the method for manufacturing an LED backlight in the present disclosure, and are examples in which the laminated body in the present disclosure is used. For example, as shown in FIG. 13A, the LED substrate 11 and the laminate 40 of the diffusion member 1 and the encapsulant sheet 21a are prepared, and the encapsulant is placed on the surface side of the LED substrate 11 on the LED element 13 side. By laminating the sheets 21a and then crimping the sealing material sheet 21a to the LED substrate 11 by using, for example, a vacuum lamination method, the LED element 13 is sealed with the sealing member 21 as shown in FIG. 13B. Can be sealed with. Note that, in FIGS. 13A and 13B, in the LED substrate 11, the surface on which the LED element 13 of the support substrate 12 is arranged, which is a region other than the LED element mounting region on which the LED element 13 is mounted. An example in which the reflective layer 15 is arranged is shown.

On the other hand, in the LED backlight, when the sealing member contains a curable resin such as a thermosetting resin or a photocurable resin, a liquid sealing material is usually used. In this case, for example, as shown in FIG. 14A, a mold 101 is arranged around the LED substrate 11, and a liquid encapsulant containing a curable resin on the surface side of the LED substrate 11 on the LED element 13 side. By applying 21b to form a coating film and then curing the coating film by heat treatment, the LED element 13 can be sealed with the sealing member 21'as shown in FIG. 14 (b).

In the case of a curable resin, since a liquid encapsulant is used, a phenomenon may occur in which the thickness of the end portion becomes thicker or thinner than that of the central portion due to surface tension or the like (FIG. 14 (FIG. 14). a) See).

Further, in the case of a curable resin, volume shrinkage or the like is likely to occur during curing, and as a result, as shown in FIG. 14 (b), the thickness of the central portion and the end portion of the sealing member after curing is non-uniform. May be. Note that FIG. 14B shows an example in which the thickness of the end portion of the sealing member 21'is thicker than the thickness of the central portion, but the thickness distribution is not limited to this, and for example, the thickness of the end portion. May be thinner than the thickness of the central part.

When the thickness is different between the central portion and the end portion of the sealing member, for example, when tiling a plurality of LED backlights to increase the size, the thickness at the boundary of each LED backlight is different. As a result, it is recognized as a seam. Therefore, when the tiling LED backlight is used for the display device, the aesthetic appearance of the display as the display device may be spoiled.

On the other hand, when a sheet-shaped encapsulant is used, the thickness distribution of the coating film due to surface tension and the thickness distribution due to heat shrinkage or light shrinkage, which occur when a liquid encapsulant is used, It is possible to avoid the occurrence of surface irregularities of the sealing member such as generation. Therefore, a sealing member having good flatness can be obtained, and a high-quality display device can be provided. Therefore, according to the present disclosure, it is possible to obtain a sealing member having good flatness by having the above-mentioned sealing material sheet. In particular, it is useful when tiling using an LED substrate having a size called a mini LED or a micro LED.

Hereinafter, the first embodiment of the laminated body of the present disclosure will be described.

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

The arrangement of the diffusion member and the sealing material sheet is appropriately selected according to the type of the first layer of the diffusion member and the like, and for example, as shown in FIG. 12, on one surface of the second layer 3 of the diffusion member 1. The first layer 2 may be arranged directly or via an adhesive layer or an adhesive layer (not shown), and the sealing material sheet 21a may be directly arranged on the surface side of the diffusion member 1 on the first layer 2 side. As shown in a), the first layer 2 is arranged directly on one surface of the second layer 3 of the diffusion member 1 or via an adhesive layer or an adhesive layer (not shown), and is on the side of the first layer 2 of the diffusion member 1. The sealing material sheet 21a may be arranged on the surface side via the low refractive index layer 43, and as shown in FIG. 15B, the diffusion member 1 is directly placed on one surface of the sealing material sheet 21a. The first layer 2 may be arranged, and a gap portion may be arranged between the first layer 2 and the second layer 3 of the diffusion member 1. As shown in FIG. 15 (c), the second layer of the diffusion member 1 may be arranged. The first layer 2 may be directly arranged on one surface of the layer 3, and a gap portion may be arranged between the diffusion member 1 and the sealing material sheet 21a. When the first layer of the diffusing member is, for example, a diffusing agent-containing resin film, any of the above-mentioned arrangements of the diffusing member and the encapsulant sheet may be used.
On the other hand, when the first layer of the diffusion member is, for example, a transmission type diffraction grating or a microlens array, a gap is arranged between the first layer and the second layer of the diffusion member, or the diffusion member It is necessary that a gap portion is arranged between the first layer and the encapsulant sheet, or a low refractive index layer is arranged between the first layer of the diffusion member and the encapsulant sheet.

When the first layer of the diffusion member is directly arranged on one surface of the encapsulant sheet, for example, as shown in FIG. 15B, a pattern is formed on one surface of the encapsulant sheet 21a. The first layer 2 of the above may be arranged. For example, when the first layer exhibits light diffusivity on a surface, it can exhibit light diffusivity even when the first layer is arranged in a pattern.

When the gap portion is arranged between the first layer and the second layer of the diffusion member, the first layer 2 and the second layer 3 may be in contact with each other, for example, as shown in FIG. 15 (b), and are not shown. However, the first layer and the second layer 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 can be arranged between the first layer and the second layer. Further, when the gap portion is arranged between the diffusion member and the encapsulant sheet, for example, the first layer of the diffusion member and the encapsulant sheet may be in contact with each other, and the diffusion is performed as shown in FIG. 15 (c). The first layer of the member and the encapsulant sheet may not be in contact with each other. When the first layer of the diffusion member and the encapsulant sheet are not in contact with each other, for example, a spacer can be arranged between the diffusion member and the encapsulant sheet. Further, the void portion can be an air layer.

When the first layer of the diffusing member is directly arranged on one surface of the encapsulant sheet, for example, by a printing method or resin shaping by a mold, the first layer of the diffusing member is placed on one surface of the encapsulant sheet. One layer can be formed directly.

2. 2. Encapsulant sheet The encapsulant sheet in the present disclosure is a member used for encapsulating an LED element and composed of an encapsulant composition containing a thermoplastic resin.

The encapsulant sheet has light transmission. The "light transmission" and "transparency" in the encapsulant sheet may be transparent to the extent that the visibility of the light from the LED element is not impaired.

(1) Material of Encapsulant Sheet The encapsulant sheet in the present disclosure is composed of an encapsulant composition containing a thermoplastic resin.

As the thermoplastic resin used for the encapsulant sheet in the present disclosure, a resin that does not substantially generate a component (deterioration component) that deteriorates the LED substrate is usually used. Here, the "resin that does not substantially generate a deterioration component" is a resin that does not contain the deterioration component itself or that does not affect the deterioration of the LED substrate even if it is contained, or the manufacture of an LED backlight. It refers to a resin that does not generate deterioration components at the time and during use, or even if it does occur, it does not affect the deterioration of the LED substrate.

Examples of the resin in which such a deteriorated component is generated include ethylene-vinyl acetate copolymer (EVA) that generates an acid component as a deteriorated component.

Further, the thermoplastic resin in the present disclosure has a melt viscosity that can follow the unevenness of the LED element and other members arranged on one surface side of the LED substrate and enter the gap by heating. Those having are preferably used.

Specifically, the melt mass flow rate (MFR) of the thermoplastic resin used is preferably 0.5 g / 10 minutes or more and 40 g / 10 minutes or less, and 2.0 g / 10 minutes or more and 40 g / 10 minutes or less. Is more preferable. When the MFR is within the above range, it is possible to enter the gap of the LED element, exhibit sufficient sealing performance, and further, the sealing member has excellent adhesion to the LED substrate. Because it can be done.

The MFR in the present specification means a value measured by JIS K7210 at 190 ° C. and a load of 2.16 kg. However, the MFR of polypropylene resin refers to the value of MFR at 230 ° C. and a load of 2.16 kg according to JIS K7210.

As for the MFR when the encapsulant sheet is a multi-layer member as described later, the measurement is performed by the above measurement method while all the layers are integrally laminated, and the obtained measured value is used to encapsulate the multilayer. It shall be the MFR value of the member.

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

In the present disclosure, as the thermoplastic resin, for example, an olefin resin, an ionomer resin, a polyvinyl butyral resin, or the like can be used.

Above all, the thermoplastic resin is preferably an olefin resin. This is because the olefin-based resin is particularly unlikely to generate a component that deteriorates the LED substrate and has a low melt viscosity, so that the above-mentioned LED element can be satisfactorily sealed. Further, among the olefin resins, polyethylene resins or polypropylene resins are preferable.

Here, the polyethylene-based resin in the present specification is obtained by polymerizing not only ordinary polyethylene obtained by polymerizing ethylene but also a compound having an ethylenically unsaturated bond such as α-olefin. Included are resins, resins in which a plurality of different compounds having an ethylenically unsaturated bond are copolymerized, modified resins obtained by grafting different chemical species to these resins, and the like.

Among them, a silane copolymer obtained by copolymerizing an α-olefin and an ethylenically unsaturated silane compound as a comonomer (hereinafter, also referred to as “silane copolymer”) can be preferably used. This is because by using such a resin, higher adhesion between the LED substrate and the sealing member can be obtained. As the silane copolymer, those described in JP-A-2018-50027 can be used.

(2) Structure of 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, for example, as shown in FIG. Further, as shown in FIG. 16, the sealing material sheet 21a may be a multilayer member in which a plurality of resin layers (three layers in FIG. 16) are laminated.

In the case of the multi-layer member, the layer located on the side opposite to the diffusion member side in the multi-layer member, that is, the layer located on the LED substrate side, has good adhesion, which is usually expensive, and good molding property of being able to enter into a gap of an LED element or the like. Materials can be used. The multilayer member may have a two-layer structure, but a three-layer structure in which layers having good adhesion are arranged on both sides is preferable.

In the multilayer member, the material constituting the layer located on the side opposite to the diffusion member side, that is, the layer arranged on the LED substrate side is particularly limited as long as it has high adhesion and high molding property. However, in the case of the above-mentioned thermoplastic resin, for example, it is preferable to use the above-mentioned silane copolymer or the like. Further, in the case of the thermoplastic resin, it is also preferable that the material contains the olefin resin and the silane coupling agent.

The thickness of the encapsulant sheet can be appropriately selected depending on the layer structure of the LED substrate and the like, 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. Further, 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 sealing member 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 transmission may be adversely affected.

When the encapsulant sheet is a three-layer multi-layer member, the thickness of the layer located at the center of the three layers may be, for example, 60 μm or more, 100 μm or more, or 250 μm or more. It may be 400 μm or less, or 350 μm or less. Further, in this case, the thickness of each of the three layers located on the outer side may be, for example, 15 μm or more and 200 μm or less.

The "thickness" in the present specification can be measured by using a known measuring method capable of measuring a size on the order of μ, and as an example, observation with an optical microscope or a scanning electron microscope (SEM). It can be measured using an image. The same applies to the measurement of size such as "size".

(3) Others The encapsulant composition used for the encapsulant sheet may contain a thermoplastic resin, and if necessary, a cross-linking agent, a silane coupling agent, an antioxidant, a light stabilizer, etc. , Other additives may be contained. Further, the method for molding the encapsulant sheet can be the same as the method for molding a general resin sheet. An example is, but is not limited to, the T-die method.

(4) Specific Aspects of Encapsulant Sheet As described above, the encapsulant sheet contains a thermoplastic resin, more preferably an olefin resin, and preferably a polyethylene resin. More preferred. In particular, it is preferable that the sealing material sheet uses a polyethylene resin having a density of 0.870 g / cm ³ or more and 0.930 g / cm ³ or less as a base resin. This is because such a sealing material sheet has good adhesion to the LED substrate and has good followability to the members arranged on the LED substrate.

Hereinafter, the details of the suitable encapsulant sheet will be described.

The encapsulant sheet is a resin film using a polyethylene resin of 0.870 g / cm ³ or more and 0.930 g / cm ³ or less as a base resin. That is, the sealing material sheet is a sealing material sheet using the above-mentioned polyethylene resin as a base resin.

The encapsulant sheet is preferably a multilayer film composed of a plurality of layers including a core layer and skin layers arranged on both outermost surfaces. In this case, the core layer preferably uses a polyethylene resin having a density of 0.910 g / cm ³ or more and 0.930 g / cm ³ or less as the base resin, and the skin layer has a density of 0.890 g / cm. It is preferable to use a polyethylene-based resin having a density of ³ or more and 0.910 g / cm ³ or less and lower than the base resin for the core layer as the base resin.

In the case of the multilayer film, the total thickness is preferably, for example, 100 μm or more, more preferably 250 μm or more, and further preferably 300 μm or more. The total thickness is preferably, for example, 600 μm or less, and more preferably 550 μm or less. If the total thickness is too thin, the impact cannot be sufficiently mitigated, but if the total thickness is within the above range, the molding property and the heat resistance can be sufficiently combined at a preferable level. If the total thickness is too thick, the effect of further improving the impact mitigation effect cannot be obtained, the request for thinning cannot be met, and it is uneconomical.

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

The encapsulant sheet is obtained by molding a encapsulant composition, which will be described in detail below, by a conventionally known method into a sheet.

When the encapsulant sheet is formed as a encapsulant member, the encapsulant composition used for manufacturing each layer uses a composition having a different density range for each layer as a base resin.

In this case, as the encapsulant composition, the encapsulant composition for the core layer and the encapsulant composition for the skin layer are used properly for forming each layer. Then, by forming a multilayer film having a three-layer structure in which the skin layers are arranged on both outermost surfaces with a predetermined thickness by using each of the encapsulant compositions for the core layer and the skin layer, for example, FIG. As shown in the above, a sealing material sheet 21a having a three-layer structure of a skin layer 22a, a core layer 23, and a skin layer 22b can be manufactured.

The base resin of the encapsulant composition for the core layer of the encapsulant sheet is a low-density polyethylene-based resin (LDPE), a linear low-density polyethylene-based resin (LLDPE), or a metallocene-based linear low-density polyethylene-based resin. A resin (M-LLDPE) can be preferably used.
Among them, from the viewpoint of long-term reliability, low-density polyethylene-based resin (LDPE) can be particularly preferably used as the composition for the core layer.

The density of the polyethylene-based resin used as the base resin of the encapsulant composition for the core layer is 0.910 g / cm ^{3 or more and 0.930 g / cm 3 or less, and more preferably 0.920 g / cm 3 or less} . Is. 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.

The melting point of the encapsulant composition for the core layer is preferably 90 ° C. or higher and 135 ° C. or lower, and more preferably 100 ° C. or higher and 115 ° C. or lower. By setting the melting point of the core layer to the above melting point range, the heat resistance and molding characteristics of these encapsulant compositions can be maintained within a preferable range. By adding a high melting point resin such as polypropylene to the encapsulant composition for the core layer, the melting point of the encapsulant composition can be raised to about 135 ° C. In this case, 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 component of the core layer.

The polypropylene contained in the core layer is preferably a homopolypropylene (homoPP) resin. Homo PP is a polymer composed of only polypropylene and has high crystallinity, and therefore has higher rigidity than block PP and random PP. By using this as an additive resin to the encapsulant composition for the core layer, the dimensional stability of the encapsulating member can be enhanced. Further, the homo-PP used as an additive resin to the encapsulant composition for the core layer has an MFR of 5 g / 10 minutes or more and 125 g / 10 minutes or less at 230 ° C. and a load of 2.16 kg measured according to JIS K7210. It is preferable to have. If the MFR is too small, the molecular weight becomes large and the rigidity becomes too high, and it becomes difficult to secure the preferable sufficient flexibility of the encapsulant composition. Further, if the MFR is too large, the fluidity during heating is not sufficiently suppressed, and heat resistance and dimensional stability cannot be sufficiently imparted to the encapsulant sheet.

The melt mass flow rate (MFR) of the polyethylene-based resin used as the base resin of the encapsulant composition for the core layer is 2.0 g / 10 minutes or more and 7.5 g / 10 minutes or less at 190 ° C. and a load of 2.16 kg. It is preferably 3.0 g / 10 minutes or more and 6.0 g / 10 minutes or less. By setting the MFR of the base resin of the encapsulant composition for the core layer in the above range, the heat resistance and the molding characteristics of the encapsulating member can be maintained within a preferable range. In addition, it is possible to sufficiently improve the processing aptitude at the time of film formation and contribute to the improvement of the productivity of the sealing member.

The content of the base resin with respect to all the resin components in the encapsulant composition for the core layer is 70% by mass or more and 99% by mass or less, preferably 90% by mass or more and 99% by mass or less. Other resins may be contained as long as the base resin is contained within the above range.

As the base resin of the encapsulant composition for the skin layer of the encapsulant sheet, the low density polyethylene resin (LDPE) and the linear low density polyethylene resin are the same as the encapsulant composition for the core layer. (LLDPE) or metallocene-based linear low-density polyethylene-based resin (M-LLDPE) can be preferably used. Among them, from the viewpoint of molding characteristics, a metallocene-based linear low-density polyethylene-based resin (M-LLDPE) can be particularly preferably used as a sealing material composition for a skin layer.

The density of the polyethylene-based resin used as the base resin of the encapsulant composition for the skin layer is 0.890 g / cm ³ or more and 0.910 g / cm ³ or less, more preferably 0.899 g / cm. It is ³ or less. By setting the density of the base resin of the sealing material composition for the skin layer within the above range, the adhesion of the sealing member can be maintained within a preferable range.

The melting point of the encapsulant composition for the skin layer is preferably 55 ° C. or higher and 100 ° C. or lower, and more preferably 80 ° C. or higher and 95 ° C. or lower. By setting the melting point of the sealing material composition for the skin layer within the above range, the adhesion of the sealing member can be further reliably improved.

The melt mass flow rate (MFR) of the polyethylene resin used as the base resin of the encapsulant composition for the skin layer is 2.0 g / 10 minutes or more and 7.0 g / 10 minutes or less at 190 ° C. and a load of 2.16 kg. It is preferably 2.5 g / 10 minutes or more and 6.0 g / 10 minutes or less. 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 the preferable range. In addition, it is possible to sufficiently improve the processing aptitude at the time of film formation and contribute to the improvement of the productivity of the encapsulant sheet.

The content of the base resin with respect to all the resin components in the encapsulant composition for the skin layer is 60% by mass or more and 99% by mass or less, preferably 90% by mass or more and 99% by mass or less.
Other resins may be contained as long as the base resin is contained within the above range.

In all the encapsulant compositions described above, a silane copolymer obtained by copolymerizing an α-olefin and an ethylenically unsaturated silane compound as a comonomer is added to each encapsulant composition, if necessary. It is more preferable to contain a certain amount. Since such a graft copolymer has a high degree of freedom of silanol groups that contribute to adhesive strength, it is possible to improve the adhesiveness of the encapsulant sheet to other members.

Examples of the silane copolymer include the silane copolymer described in JP-A-2003-46105. By using the above silane copolymer as a component of the encapsulant composition, it is excellent in strength, durability, etc., and also excellent in weather resistance, heat resistance, water resistance, light resistance, and other various properties. It has extremely excellent heat fusion properties without being affected by manufacturing conditions such as heat pressure bonding when arranging the encapsulant sheet, and the encapsulant sheet can be stably obtained at low cost.

As the silane copolymer, any of a random copolymer, an alternating copolymer, a block copolymer, and a graft copolymer can be preferably used, but the silane copolymer may be a graft copolymer. More preferably, a graft copolymer obtained by polymerizing polyethylene for polymerization as a main chain and an ethylenically unsaturated silane compound as a side chain is further preferable. Since such a graft copolymer has a high degree of freedom of silanol groups that contribute to the adhesive force, the adhesiveness of the encapsulant sheet can be improved.

The content of the ethylenically unsaturated silane compound when constituting the copolymer of the α-olefin and the ethylenically unsaturated silane compound is, for example, 0.001% by mass or more 15 with respect to the total polymer mass. It is preferably by mass% or less, preferably 0.01% by mass or more and 5% by mass or less, and particularly preferably 0.05% by mass or more and 2% by mass or less. When the content of the ethylenically unsaturated silane compound constituting the copolymer of the α-olefin and the ethylenically unsaturated silane compound is large, the mechanical strength and heat resistance are excellent, but when the content is excessive, It tends to be inferior in tensile elongation, heat fusion property, and the like.

The content of the silane copolymer encapsulant composition with respect to all resin components is 2% by mass or more and 20% by mass or less in the encapsulant composition for the core layer, and the encapsulant for the skin layer. In the composition, it is preferably 5% by mass or more and 40% by mass or less. 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 above silane copolymer is preferably about 1.0% by mass or more and 3.0% by mass or less. The preferred silane copolymer content range in the encapsulant composition is based on the premise that the silane modification amount is within this range, and may be appropriately fine-tuned according to the fluctuation of the modification amount. desirable.

Adhesion improvers can also be added to all encapsulant compositions as appropriate. By adding the adhesion improver, the adhesion durability with other members can be made higher. 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 can be particularly preferably used.

3. 3. Wavelength conversion member In the laminated body of the present disclosure, for example, as shown in FIG. 17A, the wavelength conversion member 41 may be arranged on the surface side of the diffusion member 1 on the second layer 3 side, and FIG. As shown in b), the wavelength conversion member 41 may be arranged between the diffusion 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. Diffusion member”.

4. Optical member In the laminated body of the present disclosure, for example, as shown in FIG. 17B, the optical member 42 may be arranged on the surface side of the diffusion member 1 on the second layer 3 side. The optical member may be the same as the optical member described in the above section "A. Diffusion member".

5. Other Configurations In the laminated body of the present disclosure, for example, as shown in FIG. 15A, when the low refractive index layer 43 is arranged 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. Since the refractive index of the low refractive index layer is lower than the refractive index of the first layer of the diffusion member, total reflection can be suppressed. Further, in the laminate of the present embodiment, as described above, the surface on the sealing material sheet side is used as the incident surface of the light of the LED element, and the first layer of the diffusion member is, for example, a transmissive diffraction grid or a micro. In the case of a lens array, a low refractive index layer having a refractive index different from that of the first layer is arranged on the incident side of the light of the first layer of the diffusing member, so that the light is diffracted by a transmission diffractive grid. Or the light can be refracted by a microlens array.

The refractive index of the low refractive index layer may be lower than the refractive index of the first layer of the diffusion member, and may be, for example, 1.0 or more and 1.5 or less. Further, the difference in refractive index between the low refractive index layer and the first layer of the diffusion member is preferably large, and may be, for example, 0.3 or more and 1.0 or less. Since the difference in refractive index between the low refractive index layer and the first layer of the diffusing member is large, the refraction angle can be increased when the first layer is, for example, a microlens array or a diffusing agent-containing resin film. When one layer is, for example, a transmission type diffraction grating, the diffraction angle can be increased.

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 the resin and the low refractive index particles, the low refractive index particles may be, for example, either inorganic particles or organic particles. Further, the low refractive index particles may be hollow particles. Further, as the resin, for example, a curable resin can be used.

II. Second Embodiment of the Laminate A second embodiment of the laminate in the present disclosure includes a transmission type diffraction grating or a microlens array, a diffusion member having a dielectric multilayer film, and the transmission type diffraction grating of the above-mentioned diffusion member. Alternatively, the sealing material sheet is provided on the surface side of the microlens array side and is used for sealing the LED element, and the sealing material sheet is a sealing material composition containing a thermoplastic resin. It is a member composed of. When the laminate of the present embodiment is used, the surface on the sealing material sheet side is used as the incident surface of the light of the LED element.

In the second embodiment of the laminated body in the present disclosure, the same effect as the first embodiment of the above-mentioned laminated body can be obtained.

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

As for the arrangement of the diffuser member and the encapsulant sheet, for example, a transmission diffractive lattice or a microlens array is arranged directly on one surface of the dielectric multilayer film of the diffuser member or via an adhesive layer or an adhesive layer, and the diffuser member is arranged. The encapsulant sheet may be arranged via a low refractive index layer on the surface side of the transmissive diffractive grid or the microlens array side of the above, and the transmissive diffractive grid of the diffusing member or the transmissive diffractive grid on one surface of the encapsulant sheet. The microlens array may be directly arranged and a gap may be arranged between the dielectric multilayer film of the diffusing member and the transmission diffractive lattice or the microlens array, and may be arranged on one surface of the dielectric multilayer film of the diffusing member. A transmission diffractive lattice or a microlens array may be directly arranged, and an air gap may be arranged between the diffuser member and the encapsulant sheet.

Regarding the configuration in the case where the gap portion is arranged between the transmissive diffraction grating or the microlens array of the diffusing member and the dielectric multilayer film, the first layer of the diffusing member and the first layer of the diffusing member and the first embodiment of the above-mentioned laminated body are described. It can be the same as the case where the gap portion is arranged between the second layers. Further, regarding the configuration in which the gap portion is arranged between the diffusion member and the encapsulant sheet, the void portion is arranged between the diffusion member and the encapsulant sheet in the first embodiment of the above-mentioned laminated body. It can be the same as the case where.

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

Further, the encapsulant sheet in the present embodiment can be the same as the encapsulant sheet in the first embodiment of the above-mentioned laminated body.

Further, the low refractive index layer in the present embodiment can be the same as the low refractive index layer in the first embodiment of the above-mentioned laminated body.

In the laminated body in the present embodiment, the wavelength conversion member may be arranged on the surface side of the dielectric multilayer film side of the diffusion member, and the wavelength conversion member is arranged between the diffusion member and the sealing material sheet. You may. The wavelength conversion member may be the same as the wavelength conversion member described in the above section “A. Diffusion member”.

Further, in the laminated body in the present embodiment, the optical member may be arranged on the surface side of the diffusion member on the dielectric multilayer film side. The optical member may be the same as the optical member described in the above section "A. Diffusion member".

C. Diffusion member set The diffusion member set in the present disclosure has a first member having a first layer, a sealing material sheet used for sealing an LED element, and a second layer, and has the above-mentioned first layer. A second member is provided on the surface of one member on the side of the first layer via a gap portion, the first layer has light transmittance and light diffusivity, and the second layer has light transmittance and light diffusivity. The reflectance 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 the absolute value of the incident angle of light on the surface of the second layer on the first layer side increases. The transmittance increases as the amount of light increases, and the encapsulant sheet is composed of an encapsulant composition containing a thermoplastic resin.

As shown in FIG. 18, the set 60 of the diffusion member includes a first member 61 having a first layer 2 and a sealing material sheet 21a used for sealing the LED element, and a second layer 3. The second member 62 is provided. The second member 62 is used by being arranged on the surface of the first member 61 on the side of the first layer 2 via a gap portion. The first layer 2 has light transmission and light diffusivity. Further, the second layer 3 has an incident angle dependence of the reflectance and an incident angle dependence of the transmittance.

In the set of diffusion members in the present disclosure, the same effect as that of the above-mentioned laminated body can be obtained.

The first member and the second member are separate members, and can be used as a diffusion member by arranging the first member and the second member through the gap portion.

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

Further, the encapsulant sheet in the present disclosure is the same as the encapsulant sheet described in the above-mentioned "B. Laminated body" section.

In the first member, a wavelength conversion member may be arranged between the first layer and the sealing material sheet. On the other hand, in the second member, the wavelength conversion member may be arranged on one surface of the second layer. Further, in the second member, the optical member may be arranged on one surface of the second layer. The wavelength conversion member and the optical member can be the same as the wavelength conversion member and the optical member described in the above section “A. Diffusion member”.

D. LED Backlight The LED backlight in the present disclosure has two embodiments. Hereinafter, each embodiment will be described.

I. First Embodiment of LED Backlight The first embodiment of the LED backlight of the present disclosure is an LED substrate in which a plurality of LED elements are arranged on one surface side of a support substrate, and an LED substrate side of the LED substrate. It is arranged on the surface side and includes a diffusion member having a first layer and a second layer in order from the LED substrate side. The first layer has light transmission and light diffusivity, and the second layer has light transmission and light diffusivity. As the absolute value of the incident angle of light on the surface of the second layer on the first layer side decreases, the reflectance increases, and the absolute value of the incident angle of light on the surface of the second layer on the first layer side increases. It is a device in which the transmittance increases as the amount of light increases. The LED backlight of the present disclosure is a direct type LED backlight.

FIG. 2 is a schematic cross-sectional view showing an example of the LED backlight of the present disclosure. Since FIG. 2 has been described in the above section “A. Diffusion member”, the description thereof is omitted here.

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 is arranged on the LED substrate 11 in which a plurality of LED elements 13 are arranged on one surface side of the support substrate 12 and on the surface side of the LED substrate 11 on the LED element 13 side. The sealing member 21 that seals the LED element 13 and the sealing member 21 are arranged on the surface opposite to the surface of the sealing member 21 on the LED substrate 11 side, and the first layer 2 and the second layer 2 and the second are arranged in order from the sealing member 21 side. A diffusion member 1 having a layer 3 is provided. The first layer 2 in the diffusion member 1 has light transmission and light diffusivity, and the light L1, L2, L2 incident from the surface 2A opposite to the surface on the second layer 3 side of the first layer 2 'Transparent and diffuse. Further, in the second layer 3 of the diffusion member 1, the reflectance increases as the absolute value of the incident angle of light with respect to the surface 3A on the first layer 2 side of the second layer 3 decreases, and the first layer 3 of the second layer 3 increases. The transmittance increases as the absolute value of the incident angle of light with respect to the surface 3A on the layer 2 side increases. Therefore, in the second layer 3, the light L1 incident on the surface 3A on the first layer 2 side of the second layer 3 at a low incident angle θ ₁ is reflected, and the surface on the first layer 2 side of the second layer 3 is reflected. Light L2, _L2'that is incident at a high incident angle θ ₂ and θ 2'can be transmitted to 3A. In addition, in FIG. 19, in the LED board 11, the reflection layer 15 is arranged in the area other than the LED element mounting area on which the LED element 13 of the support substrate 12 is arranged. Here is an example.

In FIG. 19, the light emitted from the LED element 13 and incident on the surface 1A on the first layer 2 side of the diffusion member 1 is diffused by the first layer 2 and the light diffused through the first layer 2. Of these, the light L1 incident on the surface 3A on the first layer 2 side of the second layer 3 at a low incident angle θ ₁ is reflected by the surface 3A on the first layer 2 side of the second layer 3 and again. It can be incident on the first layer 2 and diffused. Then, among the light transmitted through the first layer 2 and diffused, the light L2 and L2'that are incident on the surface 3A on the first layer 2 side of the second layer 3 at high incident angles θ ₂ and θ _2' . Can be transmitted through the second layer 3 and emitted from the surface 1B on the second layer 3 side of the diffusion member 1.

In the present disclosure, by having the above-mentioned diffusion member, it is possible to reduce the thickness while improving the in-plane uniformity of luminance. It is also possible to reduce cost and power consumption. Further, since the distance between the LED element and the diffusion member can be shortened, the thickness of the sealing member can be reduced, and the weight can be reduced. Further, by using the above-mentioned diffusion member, the LED backlight of the present disclosure can be easily manufactured.

Hereinafter, the first embodiment of the LED backlight of the present disclosure will be described.

1. 1. Diffusion member The diffusion member in the present disclosure is arranged on the surface side of the LED substrate on the LED element side, and has a first layer and a second layer in order from the LED substrate side, and the first layer is light transmissive. In addition, the second layer has light diffusivity, and the reflectance of the second layer increases as the absolute value of the incident angle of light with respect to the surface of the second layer on the first layer side decreases, and the reflectance of the second layer increases. It is a member whose transmittance increases as the absolute value of the incident angle of light with respect to the surface on the first layer side increases.

The diffusion member in the present disclosure is the same as the member described in the above section "A. Diffusion member".
Since each member constituting the diffusion member can be the same as the content described in the above section "A. Diffusion member", the description here is omitted.

The diffusion member is arranged at a predetermined distance from the light emitting surface of the LED element of the LED substrate.
The distance between the diffusion member and the light emitting surface of the LED element of the LED substrate is, for example, preferably 5 mm or less, particularly preferably 2 mm or less, and particularly preferably 1 mm or less. If the distance is within the range, the thickness can be reduced. The lower limit of the distance is not particularly limited.

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

2. 2. LED substrate 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.

Hereinafter, the LED substrate will be described.

(1) LED element In the LED backlight of the present disclosure, the LED element functions as a light source.

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 the LED backlight is used, and examples thereof include an LED element capable of emitting white, blue, ultraviolet rays, infrared rays, or the like.

The LED element can be a chip-shaped LED element. The form of the LED element may be, for example, a light emitting unit (also referred to as an LED chip) itself, or a package LED (also referred to as a chip LED) such as a surface mount type or a chip-on-board type. The package LED can have, for example, a light emitting portion and a protective portion that covers the light emitting portion and contains a resin. Specifically, when the LED element is the light emitting unit itself, for example, a blue LED element, an ultraviolet LED element, or an infrared LED element can be used as the LED element. When the LED element is a package LED, for example, a white LED element can be used as the LED element.

When the LED backlight of the present disclosure irradiates white light by combining an LED element and a wavelength conversion member, the LED element is preferably a blue LED element, an ultraviolet LED element, or an infrared LED element. .. The blue LED element can generate white light, for example, in combination with a yellow fluorophore, or in combination with a red fluorophore and a green fluorophore. Further, the ultraviolet LED element can generate white light by combining with, for example, a red phosphor, a green phosphor and a blue phosphor. Above all, it is preferable that the LED element is a blue LED element. This is because the LED backlight of the present disclosure can irradiate high-luminance white light.

When the LED element is a white LED element, the white LED element is appropriately selected depending on the light emitting method of the white LED element or the like. Examples of the light emitting 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, a yellow phosphor, and an ultraviolet LED. Examples thereof include a combination of a red fluorescent substance, a green fluorescent substance, and a blue fluorescent substance. Therefore, the white LED element may have, for example, a red LED light emitting unit, a green LED light emitting unit, and a blue LED light emitting unit, and a protection unit containing a blue LED light emitting unit, a red phosphor, and a green phosphor. It may have a blue LED light emitting part and a protective part containing a yellow phosphor, and may contain an ultraviolet LED light emitting part and a red phosphor, a green phosphor, and a blue phosphor. It may have a protective unit. Among them, the white LED element has a blue LED light emitting unit and a protective unit containing a red phosphor and a green phosphor, has a blue LED light emitting unit and a protective unit containing a yellow fluorescent substance, or emits an ultraviolet LED. It is preferable to have a portion and a protective portion containing a red fluorescent substance, a green fluorescent substance and a blue fluorescent substance. Among these, the white LED element may have a blue LED light emitting unit and a protective unit containing a red phosphor and a green phosphor, or may have a blue LED light emitting unit and a protective unit containing a yellow phosphor. preferable. This is because the LED backlight of the present disclosure can irradiate high-luminance white light.

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

The LED elements are usually arranged at equal intervals on one surface side of the support substrate. The arrangement of the LED elements is appropriately selected according to the use and size of the LED backlight of the present disclosure, the size of the LED elements, and the like. Further, the arrangement density of the LED element is also appropriately selected according to the use and size of the LED backlight of the present disclosure, the size of the LED element, and the like.

The size (chip size) of the LED element is not particularly limited, and may be a general chip size. Further, the size of the LED element may be a chip size called a mini LED or a micro LED. Above all, when the sealing member is arranged, it is preferable that the chip size is called a mini LED. Specifically, the size of the LED element may be several hundred micrometer square or several tens of micrometer 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 element can be arranged at a 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, uneven brightness can be suppressed. Therefore, it is possible to further reduce the thickness. Further, 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 the weight can be reduced.

(2) Support substrate The support substrate in the present disclosure is a member that supports the above-mentioned LED element or the like.

The support substrate may be transparent or opaque. Further, the support substrate may have flexibility or rigidity. The material of the support substrate may be an organic material, an inorganic material, or a composite material in which both the organic material and the inorganic material are composited.

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. Further, as the support substrate, for example, a metal core substrate can be used. As the support board, a printed circuit board in which a circuit is formed by printing can also be used.

The thickness of the support substrate is not particularly limited, and is appropriately selected depending on the presence or absence of flexibility or rigidity, the use and size of the LED backlight of the present disclosure, and the like.

(3) Others 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 may have a necessary configuration as appropriate. Examples of such a configuration include a wiring portion, a terminal portion, an insulating layer, a reflective layer, a heat radiating member, and the like. Each configuration can be the same as that used for known LED substrates.

The wiring portion is electrically connected to the LED element. The wiring portions are usually arranged in a pattern. Further, the wiring portion can be arranged on the support substrate via the adhesive layer. As the material of the wiring portion, for example, a metal material, a conductive polymer material, or the like can be used.

The wiring portion is electrically connected to the LED element by a joint portion. As the material of the bonding portion, for example, a bonding agent or solder having a conductive material such as a metal or a conductive polymer can be used.

A reflective layer can be arranged in an area other than the LED element mounting area, which is a surface on which the LED element of the support substrate is arranged. The light reflected by the second layer of the diffusion member can be reflected by the reflection layer of the LED substrate and again incident on the first layer of the diffusion member, so that the light utilization efficiency can be improved.

The reflective layer can be the same as the reflective layer generally used for an LED substrate. Specific examples of the reflective layer include a white resin film containing metal particles, inorganic particles or a pigment and a resin, a metal film, a porous film and the like. The thickness of the reflective layer is not particularly limited as long as it can obtain a desired reflectance, and is appropriately set.

The method for forming the LED substrate can be the same as the known forming method.

3. 3. Other Members In the LED backlight of the present disclosure, the space between the LED substrate and the diffusion member may be, for example, as shown in FIG. 2, and the LED element is sealed as shown in FIGS. 19 and 20. The sealing members 21 and 14 to be stopped may be arranged.

When there is a space between the LED substrate and the diffusion member, a spacer can be arranged between the LED substrate and the diffusion member. The spacer can be the same as the spacer used for a general LED backlight.

Further, as described above, when the size of the LED element is small, the LED element can be arranged at a high density, that is, the interval (pitch) between the LED elements can be reduced, so that the distance between the LED substrate and the diffusion member can be reduced. Even if it is shortened, uneven brightness can be suppressed. When the distance between the LED substrate and the diffusion member is short as described above, the sealing member can be arranged between the LED substrate and the diffusion member.

(1) Sealing member The sealing member in the present disclosure is a member arranged on the surface side of the LED substrate on the LED element side and sealing the LED element. The sealing member has light transmission and is arranged on the light emitting surface side of the LED substrate.

The "light transmission" and "transparency" in the sealing member may be transparent to the extent that the visibility of the light from the LED element is not impaired.

The material included in the sealing member in the present disclosure is not particularly limited as long as it can seal the LED element, and is, for example, a thermosetting resin, a photocurable resin, a thermoplastic resin, or the like. Can be mentioned.

Of these, thermoplastic resins are preferable. The reason why the thermoplastic resin is preferable is described in the above section "B. Laminated body", and thus the description thereof is omitted here.
explain.

The thermoplastic resin used for the sealing member in the present disclosure is the same as the thermoplastic resin described in the above-mentioned "B. Laminated body 2. Sealing material sheet".

As the thermosetting resin used for the sealing member in the present disclosure, a thermosetting resin generally used for the sealing member of the LED backlight can be adopted, for example, a silicone-based resin, an epoxy-based resin, or the like. Can be mentioned.

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

The sealing member in the present disclosure may be, for example, a single-layer member in which the sealing member 21 is composed of a single resin layer, as shown in FIG. 19, and as shown in FIG. 21, the sealing member may be a sealing member. 21 may be a multilayer member in which a plurality of resin layers (three layers in FIG. 21) are laminated. For example, as shown in FIG. 21, the sealing member 21 has a three-layer structure consisting of a skin layer 22a, a core layer 23, and a skin layer 22b.

The structure of the sealing member can be the same as the structure of the sealing material sheet in the laminated body.

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

The details of the sealing member can be the same as those described in the above section "B. Laminated body 2. Sealing material sheet".

The thickness of the sealing member is appropriately set according to the distance between the above-mentioned diffusion member and the light emitting surface of the LED element of the LED substrate.

(2) Wavelength conversion member The wavelength conversion member is usually arranged on the light emitting surface side of the LED substrate, and is arranged on the observer side of the LED element. In the LED backlight of the present disclosure, the wavelength conversion member may be arranged on the surface side of the first layer side or the surface side of the second layer side of the diffusion member. When the sealing member is arranged, the wavelength conversion member 41 is arranged on the surface side of the diffusion member 1 on the second layer 3 side, for example, as shown in FIG. 22A. As shown in FIG. 22B, the wavelength conversion member 41 may be arranged between the diffusion 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. Diffusion member”.

(3) Optical member In the LED backlight of the present disclosure, an optical member may be arranged on the surface side of the diffusion member on the second layer side. The optical member may be the same as the optical member described in the above section "A. Diffusion member".

II. Second Embodiment of LED Backlight The second embodiment of the LED backlight of the present disclosure is an LED substrate in which a plurality of LED elements are arranged on one surface side of a support substrate, and an LED substrate side of the LED substrate. The diffuser member includes a diffuser member arranged on the surface side, and the diffuser member is an apparatus having a transmissive diffraction grid or a microlens array and a dielectric multilayer film in order from the LED substrate side. The LED backlight of the present embodiment is a direct type LED backlight.

In the LED backlight of this embodiment, the same effect as that of the first embodiment of the above-mentioned LED backlight can be obtained.

The diffusion member in this embodiment is the same as the member described in the above section "A. Diffusion member II. Second embodiment". Since each member constituting the diffusion member can be the same as the content described in the above section "A. Diffusion member II. Second embodiment", the description thereof is omitted here.

The distance between the diffuser member and the light emitting surface of the LED element of the LED substrate can be the same as that of the first embodiment of the LED backlight described above.

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

The other members in this embodiment can be the same as the other members in the first embodiment of the LED backlight described above.

D. Display device The display device of the present disclosure is a device including a display panel and the above-mentioned LED backlight arranged on the back surface of the above-mentioned display panel.

23 and 24 are schematic views showing an example of the display device of the present disclosure. As illustrated in FIGS. 23 and 24, the display device 30 or 50 comprises a display panel 31 or 51 and an LED backlight 10 located on the back of the display panel 31 or 51.

According to the present disclosure, by having the above-mentioned LED backlight, it is possible to reduce the thickness while improving the in-plane uniformity of brightness. It is also possible to reduce cost and power consumption. Therefore, a high-quality display device can be obtained.

Hereinafter, each configuration in the display device of the present disclosure will be described.

1. 1. LED backlight The LED backlight in the present disclosure is the same as the member described in the above-mentioned "C. LED backlight" section. Since each member constituting the LED backlight can be the same as the content described in the above-mentioned "C. LED backlight" section, the description here is omitted.

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

The present disclosure is not limited to the above embodiment. The above embodiment is an example, and any object having substantially the same structure as the technical idea described in the claims of the present disclosure and having the same effect and effect is the present invention. Included in the technical scope of the disclosure.

Examples are shown below, and the present disclosure will be described in more detail.

An optical simulation was performed to evaluate the in-plane uniformity of brightness. The simulation was a ray tracing simulation by LightTools manufactured by Synopsys.

[Test Example 1]
(conditions)
-Structure: A diffusing member is arranged above the LED substrate.-Diffusing member: A first layer having light transmittance and light diffusivity and a second layer having an incident angle dependence of reflectance and transmittance. Laminated diffusion member / thickness of diffusion member: 0.2 mm
・ Size of diffusion member: 4 mm
-Distance from the surface of the LED board to the diffusion member: 0.5 mm
-Light transmittance of the first layer of the diffusing member: Total light transmittance 98%
-Light diffusivity of the first layer of the diffusing member: Refracts the incident light to 45 °.-Reflectance and transmittance of the second layer of the diffusing member depend on the incident angle: See FIG. 25. The simulation results are shown in FIG. 26.

[Test Example 2]
(conditions)
-Structure: Diffusing plate is arranged above the LED substrate-Diffusing member: Diffusing plate containing particles-Light transmittance and light diffusing property of the diffusing plate: Total light transmittance 95%, haze 85%
・ Thickness of diffusion member: 0.5 mm
・ Size of diffusion member: 4 mm
-Distance from the surface of the LED board to the diffusion member: 0.2 mm
The simulation result is shown in FIG. 27.

[Test Example 3]
(conditions)
-Structure: Transmission reflector and diffuser are arranged in this order above the LED substrate.-Diffuse plate: Diffuse plate containing particles-Light transmittance and light diffusivity of the diffuser: Total light transmittance 95%, Haze 85%
-Transmission reflector: A transmission reflector was manufactured by providing a through hole with a drill in an ultrafine foamed light reflector "MCPET" (0.5 mm thick) manufactured by Furukawa Electric Co., Ltd. The through hole is designed so that the diameter of the through hole located directly above the LED element is 0.25 mm, and the diameter of the through hole increases as the distance from the LED element in the plane direction increases. (See Fig. 28)
-Thickness of transmission reflector: 0.5 mm
・ Thickness of diffuser plate: 2.4 mm
・ Size of diffuser plate and transmission reflector: 24 mm
-Distance from the surface of the LED substrate to the transmissive reflector: 3.1 mm
The simulation results are shown in FIG.

[Test Example 4]
(conditions)
-Structure: An optical member is arranged above the LED substrate-Optical member: An optical member having only a second layer having an incident angle dependence of reflectance and transmittance-Thickness of the optical member (second layer): 0.05mm
-Size of optical member (second layer): 4 mm
-Distance from the surface of the LED board to the optical member: 0.5 mm
Incident angle dependence of reflectance and transmittance of optical member (second layer): See FIG. 25 The simulation results are shown in FIG.

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

Further, in Test Example 3, the in-plane uniformity of the illuminance was excellent, but the distance between the LED substrate and the transmission reflector was longer than that in Test Example 1. From Test Examples 2 and 3, it can be seen that when a conventional diffuser plate or transmission reflector is used, it is necessary to increase the distance between the LED substrate and the diffuser plate or transmission reflector in order to make the brightness uniform. From this result, when the sealing member is arranged between the LED substrate and the diffusion member or the diffusion plate or the transmission reflector, the in-plane uniformity of the luminance is improved by adopting the configuration of the diffusion member in the present disclosure. It was confirmed that it is possible to reduce the thickness and weight.

Further, 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 was improved by adopting the structure of the diffusion member of the present disclosure.

1 ... Diffusion member 2 ... 1st layer 3 ... 2nd layer 10 ... LED backlight 11 ... LED substrate 12 ... Support board 13 ... LED element 14, 21 ... Sealing member 21a ... Encapsulant sheet 15 ... Reflective layer 30, 50 ... Display device 31, 51 ... Display panel 40 ... Laminated body 60 ... Diffusion member set 61 ... First member 62 ... Second member

Claims (1)

A transmission type diffraction grating or microlens array and a dielectric multilayer film are laminated, and the dielectric multilayer film is formed with respect to the surface of the dielectric multilayer film on the transmission type diffraction grating or microlens array side. A diffusion member having a positive reflectance of 80% or more and less than 100% of visible light incident at an incident angle of 0 °.

Images