JP2010122372A - Optical functional member, backlight unit and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide: an optical functional member having improved front brightness and reduced changes in the brightness depending on a viewing angle in a perpendicular direction; a backlight unit; and a display device. <P>SOLUTION: The optical functional member 20 comprises: a light-diffusing layer 40 disposed in an entrance face side and diffusing light from a light source 11; a first lens sheet 50 layered in the exit face side of the light-diffusing layer 40 and comprising a planar light-transmitting substrate 52 and a first lens array 53 composed of a plurality of first lenses 54 extending along the exit face of the first substrate 52 and arranged in parallel to one another; and a second lens sheet 60 layered in the exit face side of the first lens sheet 50 and comprising a planar light-transmitting second substrate and a second lens array composed of a plurality of second lenses extending along the exit face of the second substrate and in a direction orthogonal to the direction of the first lenses and arranged in parallel to one another. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical functional member used for illumination optical path control, a backlight knit using the same, and a display device, and more particularly to an optical functional member used for illumination optical path control in an image display device typified by a flat panel display, The present invention relates to a backlight knit and a display device.

In recent years, display devices using TFT-type liquid crystal panels and STN-type liquid crystal panels have been commercialized mainly in color notebook PCs (personal computers) in the OA field, for example.
Such a display device employs a so-called backlight system in which a light source is arranged on the back side of the liquid crystal panel and the liquid crystal panel is illuminated with light from the light source.
The backlight units used in this type of backlight system can be broadly divided into multiple light sources such as cold cathode fluorescent lamps (CCFL) within a flat light guide plate made of acrylic resin with excellent light transmission. There are a “light guide plate light guide method” (so-called edge light method) and a “direct type method” that does not use a light guide plate.

As a display device on which a light guide plate light guide type backlight unit is mounted, for example, the display device shown in FIG. 9 is generally known.
This display device includes a liquid crystal panel 172 sandwiched between polarizing plates 171 and 173, and a light guide plate 179 made of a transparent base material such as a substantially rectangular plate-like PMMA (polymethyl methacrylate) or acrylic is installed on the back side thereof. A diffusion film (diffusion layer) 178 is provided between the upper surface (light emitting side) of the light guide plate 179 and the polarizing plate 173 on the rear side.

  On the back side of the light guide plate 179, a scattering reflection pattern portion (not shown) for scattering and reflecting the light introduced into the light guide plate 179 so as to be uniform in the direction of the liquid crystal panel 172 is printed. A reflective film (reflective layer) 177 is provided on the further back side of the scattering reflection pattern portion.

  Further, a light source lamp 176 is attached to one side end of the light guide plate 179, and covers the back side of the light source lamp 176 in order to make the light of the light source lamp 176 enter the light guide plate 179 efficiently. A high-reflectance lamp reflector 181 is provided. The scattering reflection pattern portion is formed by printing a mixture of white titanium dioxide (TiO2) powder in a transparent adhesive or the like in a predetermined pattern, for example, a dot pattern, and drying and forming the light guide plate 179. A directivity is imparted to the light incident on the inside of the light, and the light is guided to the exit surface side, thereby increasing the brightness.

  Recently, in order to improve the light utilization efficiency and increase the brightness, as shown in FIG. 10, a prism film (prism layer) having a light collecting function between the diffusion film 178 and the liquid crystal panel 172 is used. 174, 175 have been proposed. The prism films 174 and 175 are for emitting the light emitted from the light exit surface of the light guide plate 179 and diffused by the diffusion film 178 to the effective display area of the liquid crystal panel 172 with high efficiency.

However, since the control of the visual field range in the liquid crystal display device illustrated in FIG. 9 or FIG. 10 is left only to the diffusibility of the diffusion film 178, the control is difficult, and the central part in the diffusion direction goes bright and goes to the peripheral part. The characteristic which becomes so dark is inevitable. As a result, when the liquid crystal screen is viewed from the side, the luminance is greatly reduced, and the light utilization efficiency is reduced.
Furthermore, in the method using the prism films 174 and 175 illustrated in FIG. 10, two prism films 174 and 175 are required, so that not only the amount of light decreases due to absorption of the film but also the number of members increases. This also caused the cost to rise.

  On the other hand, the direct type backlight unit is used in a display device such as a large liquid crystal TV in which it is difficult to use a light guide plate. As an example using this backlight unit, for example, a display as shown in FIG. Devices are generally known.

In this display device, a liquid crystal panel 172 sandwiched between polarizing plates 171 and 173 is provided, and a light source 151 made of a fluorescent tube or the like is provided on the back side thereof. And the light radiate | emitted from the light source 151 is diffused by the diffusion film 178, and is condensed on the effective display area of the liquid crystal panel 172 with high efficiency. In order to efficiently use the light from the light source 151 as illumination light, a reflector 152 is disposed on the back surface of the light source 151.
Further, recently, in this direct type backlight unit, as in the case shown in FIG. 10, in order to increase the light utilization efficiency and increase the luminance, the diffusion film 174 and the polarizing plate 173 of the liquid crystal panel 172 are used. It is proposed to provide a prism film (prism layer) having a light condensing function.

However, even in the liquid crystal display device having the configuration illustrated in FIG. 11, since the control of the visual field range is left only to the diffusibility of the diffusion film 174, the control is difficult, and the central part in the diffusion direction is bright and the peripheral part. The darkening characteristic is inevitable. As a result, when the liquid crystal screen is viewed from the side, the luminance is greatly reduced, and the light utilization efficiency is reduced. Furthermore, in the method using a prism film, since the number of prism films is two, not only the decrease in the amount of light due to the absorption of the film increases, but also the cost increases due to an increase in the number of members. .
In FIG. 11, if the arrangement interval of the light sources 151 is too wide, uneven brightness tends to occur on the screen, the number of light sources cannot be reduced, and this causes an increase in power consumption and cost. .

By the way, in the above liquid crystal display devices, light weight, low power consumption, and high luminance are strongly demanded as market needs, and accordingly, the backlight system mounted on the liquid crystal display device is also light weight, low Power consumption and high brightness are required. In particular, in a color liquid crystal display device that has recently made remarkable progress, the panel transmittance of the liquid crystal panel is significantly lower than that of a monochrome-compatible liquid crystal panel. It has become an indispensable issue for obtaining power consumption.
However, in the conventional configuration as described above, it is difficult to say that the demand for high luminance and low power consumption is sufficiently met today, where the liquid crystal display device is further reduced in thickness. The development of a backlight system capable of realizing a liquid crystal display device with high brightness, high display quality, and low power consumption is awaited.

  In view of the above situation, the present applicant includes a liquid crystal panel and a light source means for irradiating light from the back side of the liquid crystal panel, and a lens layer for guiding the light from the light source to the liquid crystal panel. And a liquid crystal display device in which a light-shielding portion having an opening in the vicinity of the focal plane of the lens layer is provided on the light incident side of the lens layer (see, for example, Patent Document 1).

As shown in FIG. 12, the liquid crystal display device disclosed in Patent Document 1 includes a liquid crystal panel 172 sandwiched between polarizing plates 171 and 173, and is provided on the upper surface. A diffusion film 174 is provided, and a light guide plate 179 made of a substantially rectangular plate-like transparent base material is disposed below the diffusion film 174, and a reflection film (reflection layer) 177 is provided on the lower surface of the light guide plate 179. Is provided. A light source lamp 176 is disposed along the side edge of the light guide plate 179, and further, covers the back side of the light source lamp 176 so that the light from the light source lamp 176 can be efficiently incident on the light guide plate 79. Thus, a lamp reflector 181 having a high reflectivity is provided.
In addition, a lens sheet 82 having a light shielding portion 183 is disposed between the diffusion film 174 and the light guide plate 179.

  The effect obtained by interposing the lens sheet 182 is that the diffusibility of the light emitted from the light guide plate 179 can be modulated (collimated) by the lens action, and can be emitted with the direction aligned on the liquid crystal panel 172 side. It is in the point. Further, by forming the light shielding portion 183 having the opening 183a in the vicinity of the focal plane of the lens layer, it is possible to selectively increase the amount of light incident on the pixels of the liquid crystal panel 72 and improve the use efficiency of the backlight. In addition, it is possible to control the viewing zone of the display light by controlling the shape of the opening 183a.

  In addition, when the lens sheet is used in a direct type backlight unit that does not employ a light guide plate that constitutes an edge light type surface light source, a light diffusion layer (light diffusion layer alone) is provided between the light source and the lens sheet. Or a combination of a light diffusion film) is employed. By interposing the light diffusing layer, the phenomenon that the silhouette (lamp image) of the light source by the cold cathode ray tube (CCFL) or LED is strongly visualized, and a part in the screen called a hot spot or hot bar are locally The phenomenon of appearing bright is eliminated, and the display luminance distribution in the screen can be made uniform.

  When a light diffusing layer is provided on the flat surface of the lens sheet on the side opposite to the lens portion, the flat surface without a step is not clear between the flat lens sheet and the light diffusing layer. When both are substances having a refractive index close to each other, incident light does not enter the unit lens at an intended angle, and it becomes difficult to exhibit optical characteristics as designed by the unit lens. In particular, when adopting a configuration in which the lens sheet and the light diffusion layer are laminated and integrated via an adhesive layer or an adhesive layer, unexpected generation of incident light components (or deterioration of the function due to the light diffusion layer) is caused. It becomes easier to invite and it becomes more difficult to achieve optical characteristics as designed.

In view of the above circumstances, the present applicant has proposed a backlight unit having the configuration shown in FIG. 13 (see Patent Document 2).
In FIG. 13, a display backlight unit 90 includes an optical sheet 100 and a direct light source 110 disposed on the light incident side of the optical sheet 100.
The optical sheet 100 has a light diffusing layer 101 having one surface as an incident surface 101a and a surface opposite to the incident surface 101a as an output surface 101b, and light from the light source 110 incident on the light diffusing layer 101 from the incident surface 101a. And an optical function member 102 that controls at least one of the emission direction, range, color, and luminance distribution of the light when exiting from the exit surface 101b. The optical function member 102 is provided on the exit surface 101b of the light diffusion layer 101. A layered adhesive or pressure-sensitive adhesive 103 is bonded together. A light source 110 is disposed so as to face the incident surface 101 a of the light diffusion layer 101.

The optical functional member 102 includes a light-transmitting base material 1021 made of polyethylene terephthalate (PET) or the like, and a lenticular lens (repetitive array structure of striped semi-cylindrical convex cylindrical lenses) on one surface of the base material 1021. The lens sheet has a lens portion 1022 formed by arranging unit lenses 1022a having a structure such as the above at a constant pitch.
Further, on the surface opposite to the lens portion 1022 of the base material 1021, a striped light transmitting portion that transmits light to the condensing portion of each unit lens 1022a, that is, the opening 1024a and the non-condensing portion of each unit lens 1022a. A reflection layer 1024 in which light reflection portions 1024b for reflecting light are arranged is provided. The light diffusion layer 101 is integrally bonded to the surface of the reflective layer 1024 located opposite to the base material 1021 via an adhesive or pressure-sensitive adhesive 103. The reflective layer 1024 is made of, for example, white ink, a metal foil, or a metal vapor deposition layer, and the opening 1024a is made of, for example, an air layer.

Next, the behavior of light in the backlight unit 90 using the optical sheet 100 shown in FIG. 13 will be described. The light L from the light source 110 is incident from the incident surface 101a11 of the light diffusion layer 101. Here, the light L incident on the light diffusion layer 101 is randomly scattered.
Of the scattered light, only the light γ that has passed through the opening 1024a is guided to the lens sheet 1023. Since each opening 1024a is provided so as to face the apex of each unit lens 1022a provided in the lens sheet 1023, each unit lens 1022a is narrowed by each opening 1024a corresponding thereto. Only light is guided.
That is, since each opening 1024a functions like a slit, only the light γ with a narrowed scattering angle is incident on each unit lens 1022a, so that light incident on the unit lens 1022a from an oblique direction is incident. Therefore, it is possible to eliminate the light that is emitted in the lateral direction without traveling in the visual direction F of the viewer.

On the other hand, the light β that could not pass through the opening 1024a is reflected by the light reflecting portion 1024b and returned to the light diffusion layer 101 side. Then, after being similarly scattered in the light diffusion layer 101, the light γ having a narrowed scattering angle is incident on the unit lens 1022a through the opening 1024a, and the unit lens 1022a falls within a predetermined angle φ. It is emitted after being diffused.
In this way, the light L from the light source 110 is scattered, and only the light γ with a narrowed scattering angle can be incident on the unit lens 1022a, and the light that could not be incident on the unit lens 1022a is emitted wastefully. Therefore, it is possible to emit light while controlling the diffusion range while improving the utilization efficiency of the light from the light source 110.

FIG. 14 is a schematic diagram showing an example in which a liquid crystal display device is configured using the backlight unit 90 having the structure shown in FIG.
The liquid crystal display device shown in FIG. 14 includes a liquid crystal panel 122 having both surfaces sandwiched between polarizing plates 121 and 123. The liquid crystal panel 122 faces the unit lens 1022a of the lens sheet 1023 that constitutes the backlight unit 90. Is provided. Further, the light source 110 includes a plurality of lamps 110 a made up of cold cathode ray tubes and the like arranged at equal intervals along the lower surface of the backlight unit 90 on the light diffusion layer 101 side, and the light from the lamp 110 a And a reflection plate 110 b that reflects the diffusion layer 101.
JP 2000-284268 A International Publication No. WO2006 / 080530 Pamphlet

In recent years, consideration for the global environment has been demanded, and display backlight units are required to save power by effectively using the amount of light emitted from a light source. Specifically, there is a problem of developing a backlight unit that can obtain the same front luminance with a light source that emits less light than in the past.
In general, a backlight unit for a display using a brightness enhancement sheet having a lens or a unidirectional cylindrical or prism condenses light in the vertical direction to the front, and therefore changes in luminance for each viewing angle in the vertical direction. There is a tendency to increase, and the development of a brightness enhancement sheet for reducing this has been an issue.

  The present invention has been made in view of the circumstances as described above, and an optical functional member for a display that can improve the front luminance and can reduce the luminance change for each viewing angle in the vertical direction. It is to provide a backlight unit and a display device using the above.

In order to solve the above problems, the present invention proposes the following means.
That is, the optical functional member according to the present invention is an optical functional member that converts the optical characteristics of light from a light source disposed on the incident surface side and emits the light from the emitting surface, and is disposed on the incident surface side, A light diffusing layer for diffusing light from a light source; a light-transmitting first base material laminated on the light emitting surface side of the light diffusing layer; and a light transmitting first base material on the light emitting surface side of the first base material. A first lens sheet that includes a first lens array that includes a plurality of first lenses that extend along the surface and are arranged in parallel with each other; and is laminated on the emission surface side of the first lens sheet, A plate-like light-transmitting second base material and the second base material extending along the surface on the emission surface side of the second base material and extending in a direction perpendicular to the first lens and arranged in parallel to each other A second lens sheet comprising a second lens array composed of a plurality of second lenses; And wherein the Ranaru.

According to the optical function member having such a feature, for example, when the first lens array is disposed along the horizontal direction and the second lens array is disposed along the vertical direction, the first lens array causes light in the vertical direction. Is condensed and condensed, and light in the horizontal direction is condensed, condensed and emitted by the second lens array.
Thereby, since light can be narrowed down into two directions, the vertical direction and the horizontal direction, the front luminance can be improved. Also, the light in the vertical direction is narrowed by the first lens array of the first lens sheet, but the light in the vertical direction is not narrowed by the second lens array of the second lens sheet, but rather passes through the second lens sheet. By doing so, the light narrowed down in the vertical direction by the first lens sheet is diffused. As a result, light passing through the optical function member can be emitted without being excessively narrowed in the vertical direction.

  An optical functional member according to the present invention is a third lens array in which the second lens sheet is configured of a plurality of third lenses that extend along a direction orthogonal to the second lens and are arranged in parallel to each other. The second lens sheet is laminated on the first lens sheet so that one of the second lens and the third lens is parallel to the first lens. Features.

According to the optical function member having such a feature, the light in the vertical direction sufficiently narrowed in the front direction by the first lens sheet is diffused to some extent without being further narrowed by the third lens array. That is, generally, when diffused light is incident on the lens array, the light is condensed and narrowed in the front direction, but when light that has already been condensed in the front direction is incident, the light is inclined from the front direction. The light is refracted in the direction and a diffusion effect is given.
As a result, the half-value angle in the vertical direction of the light passing through the optical function member can be enlarged.

  In the optical functional member in which the third lens array is formed on the second lens sheet as described above, each of the third lenses extends discretely over the tops of the plurality of second lenses. Alternatively, each of the third lenses may be extended along a surface of the second base material on the emission surface side so that the valleys of the plurality of first lenses are higher than the first lens. A plurality of sub-lenses having a low height are formed.

  On the other hand, in the optical functional member according to the present invention, instead of forming the third lens array on the second lens sheet, each of the second lenses is a surface on the emission surface side of the second base material. And a convex curved surface formed so as to protrude from the top, and a V-shaped groove extending in the extending direction of the second lens may be formed at the top.

According to the optical functional member having such a feature, light is recycled due to total reflection of light in the horizontal direction generated between the side surface of the V-shaped groove and the air layer interface in the second lens of the second lens sheet. The light use efficiency can be improved, and the effect of increasing the brightness can be obtained. In addition, since the surfaces on both sides of the V-shaped groove of the second lens are convex curved surfaces, the side lobe can be minimized, and the function of reducing a sharp luminance drop (cutoff) with respect to the field of view. Fulfill.
Furthermore, by recycling the light in the horizontal direction by total reflection, the amount of light in the vertical direction increases because part of the light shifts to light in the vertical direction. As a result, the light in the vertical direction spreads and becomes vertical. It becomes possible to enlarge the half-value angle of the direction.

  In the optical functional member according to the present invention, the first lens has a convex curved surface shape including a first lens top portion and a pair of first lens inclined surfaces extending from the first lens top portion to the first base material. It is preferable that the distance between the pair of opposed first lens inclined surfaces is formed so as to gradually approach from the first base member toward the top of the first lens.

  In the optical functional member according to the present invention, the light diffusing layer has a plate-like light-transmitting third base material, and a plurality of back lenses arranged on the incident surface side surface of the third base material A back lens sheet comprising a back lens array, a light diffusing and transmitting layer that is laminated on the exit surface side of the back lens sheet and transmits light while diffusing, and the exit surface of the light diffusing and transmitting layer It is characterized by comprising a light diffusing plate which is laminated on the side and has a substantially plate shape and diffuses light.

  In the optical functional member according to the present invention, a plurality of the back lenses extend along the surface on the incident surface side of the third base material and are arranged in parallel to each other, and each of the back lenses has a convex curved surface shape. The back surface lens top portion and a pair of back surface lens inclined surfaces extending from the back surface lens top portion to the third base material, and the distance between the pair of opposing back surface lens inclined surfaces is from the third base material to the third base material. It is formed so that it may approach gradually as it goes to the back lens top.

  In the optical functional member according to the present invention, it is preferable that the back lens is a plurality of triangular prisms extending along the surface on the incident surface side of the third base material and arranged in parallel to each other.

  In the optical functional member according to the present invention, the back lens is a microlens arranged in a matrix on the incident surface side surface of the third substrate, and the back lens array is a microlens array. May be.

  In the optical functional member according to the present invention, it is preferable that the light diffusion plate and the light diffusion / transmission layer are integrally formed by a multilayer extrusion method.

  In the optical functional member according to the present invention, it is preferable that the light diffusing plate and the light diffusing and transmitting layer are stretched in at least one axial direction when they are integrally formed by a multilayer extrusion method.

  In the optical functional member according to the present invention, the light diffusing plate and the light diffusing / transmitting layer may be bonded and integrated by an adhesive or an adhesive.

  In the optical functional member according to the present invention, the back lens is preferably made of a transparent resin having a total light transmittance of 85% or more.

  In the optical functional member according to the present invention, the light diffusing and transmitting layer is preferably a transparent resin having a total light transmittance of 80% or more and a haze value of 95% or less.

  In the optical functional member according to the present invention, it is preferable that the light diffusing and transmitting layer does not contain light diffusing particles.

  In the optical functional member according to the present invention, it is preferable that the light diffusion / transmission layer is made of a thermoplastic resin.

  In the optical functional member according to the present invention, it is preferable that the light diffusing and transmitting layer is stretched in at least one axial direction.

  In the optical functional member according to the present invention, the light diffusion layer may be a light diffusion plate.

  In the optical functional member according to the present invention, it is preferable that the light diffusion plate has a light diffusion region dispersed in a transparent resin, has a total light transmittance of 40% to 80%, and a haze value of 98% or more. .

  In the optical function member according to the present invention, it is preferable that the light diffusion region is a light diffusion particle, and the thickness of the light diffusion layer is 0.1 to 5 mm.

  In the optical functional member according to the present invention, it is preferable that the light diffusing plate is stretched in at least one axial direction.

  In the optical function member according to the present invention, a light shielding layer that blocks light is provided between the light diffusion layer and the first lens sheet, and the light shielding layer penetrates in the thickness direction. A plurality of light transmitting apertures extending in the longitudinal direction of the first lens are formed, and each aperture is arranged at a position overlapping the top of the first lens in the thickness direction.

  The optical functional member according to the present invention may be one in which the first lens sheet and the light diffusing layer are laminated and integrated by bonding with an adhesive or an adhesive.

  The backlight unit according to the present invention includes any one of the above optical function members and a light source disposed on the incident surface side of the optical function member.

  A display device according to the present invention includes the backlight unit and an image display element that performs image display by light irradiation from the backlight unit.

  In the display device according to the present invention, the image display element is a liquid crystal display element.

  According to the optical functional member, the backlight unit, and the display device according to the present invention, the front luminance can be improved by collecting the light in the vertical direction and the horizontal direction, and the passing light is narrowed down in the vertical direction. By emitting without passing, it is possible to reduce the luminance change for each viewing angle in the vertical direction.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, about the optical function member which concerns on embodiment of this invention, it demonstrates with the backlight unit and display apparatus using the same.

As shown in FIG. 1, the display device 100 according to the embodiment is configured by providing a liquid crystal panel (image display unit) 90 on the light emission side of a backlight unit 80 that emits light upward. The liquid crystal display device displays an image from the liquid crystal panel 90 by emitting display light whose display is controlled by an image signal upward.
Hereinafter, based on such an arrangement, the upper direction in FIG. 1 may be simply referred to as the front direction or the viewer side, and the lower direction may be simply referred to as the back side.

The liquid crystal panel 90 is provided on the back side and the viewer side of a liquid crystal cell (display element or panel) 91 that controls the transmission state of light according to an image signal for each of a plurality of pixel regions formed in a rectangular grid, for example. It is configured by laminating polarizing plates 92 and 93 that control the polarization direction of light. The liquid crystal cell 91 includes a pair of glass substrates and a liquid crystal layer sandwiched between them.
The liquid crystal panel 90 is a so-called transmissive display panel, but may be a transflective display panel. Alternatively, instead of the liquid crystal panel 90 including the liquid crystal cell 91, another display panel such as a display panel that displays a still image with a light-transmitting colored pattern may be used.

  The backlight unit 80 is a light emitting device having a light emitting surface having substantially the same area as the display screen of the liquid crystal panel 90, and is configured by laminating the optical functional member 20 on the light emitting direction side of the light source unit 10. Has been. The optical function member 20 is configured by laminating a second lens sheet 60 on an optical sheet 30 provided with a first lens sheet 50 (not shown in FIG. 1).

  The light source unit 10 includes a plurality of cylinder-shaped light sources 11 extending in the depth direction of the paper, arranged at a constant pitch so as to be parallel to each other, and the back side and the side of the linear light source are lamps. A direct type system configured by being surrounded by the house 12 is adopted.

As the light source 11, a cathode tube (CCFL), LED, EL, semiconductor laser, or the like can be used.
In addition, the lamp house 12 has a box shape in which an observer side is opened, and is composed of a light reflecting film such as a white film or a white sheet, or a sheet. Note that. The lamp house 12 may be configured by attaching a film, a sheet, or the like on a support such as a metal plate.

Next, details of the optical function member 20 will be described with reference to FIG.
As described above, the optical functional member 20 is configured by laminating the second lens sheet 60 on the light emitting surface side of the optical sheet 30. In addition, the optical sheet 30 includes a light reflection layer (light-shielding layer) 70 disposed between the light diffusion layer 40 and the first lens sheet 50. The light diffusion layer 40, the light reflection layer 70, and the first light reflection layer 70 are provided. The lens sheet 50 is configured to be fixed in a laminated state.
That is, the optical functional member 20 of the present embodiment is configured by laminating the light diffusion layer 40, the light reflection layer 70, the first lens sheet 50, and the second lens sheet 60 in this order from the back side. . The optical function member 20 may be one in which the light reflection layer 70 is not provided and the first lens sheet 50 is directly laminated on the light diffusion layer 40.

  The light diffusion layer 40 plays a role of diffusing the light emitted from the light source 11 to some extent, and the back lens sheet 41, the light diffusion transmission layer 45, and the light diffusion plate 46 are laminated in this order from the back side. It is configured.

  The rear lens sheet 41 is formed in a plate shape, one surface forming a light incident surface 42a and the other surface forming a light exit surface 42b, and the third base 42 The back surface lens array 43 includes a plurality of back surface lenses 44 arranged on the incident surface 42 a of the material 42.

  The back lens 44 has a cylindrical shape protruding from the incident surface 42a of the third base material 42, and extends in the depth direction of the paper, that is, in the same direction as the extending direction of the light source 11. A plurality of lenses 44 are arranged side by side in a direction orthogonal to the extending direction, thereby forming a back lens array 43.

  The cross-sectional view of the shape of the back lens 44 is, in addition to the cylindrical shape shown in FIG. 2, for example, as shown in FIG. 3 (a), a convex curved back lens top 44a and the back lens top 44a. The distance between the pair of back surface lens inclined surfaces 44b and 44b facing each other is a distance between the third base material 42 and the back surface lens top portion 44a. It may be formed so as to gradually approach as it goes to, and may also have a triangular prism shape as shown in FIG.

  As shown in FIG. 3C, the back lens 44 may be a microlens and arranged in a matrix on the incident surface of the third base material 42. In this case, the back lens array 43 constitutes a microlens array.

  The third base material 42 is made of a light transmissive transparent resin. Examples of the transparent resin include acrylic resin, polystyrene (PS) resin, methacrylstyrene copolymer (MS) resin, and polycarbonate (PC). ) Resin, acrylonitrile styrene copolymer (AS) resin, cycloolefin polymer (COP), etc., copolymers containing these as components, or mixtures of these resins. Note that, regardless of which transparent resin is used, the total light transmittance of the transparent resin is preferably 85% or more.

  The back lens 44 uses a thermoplastic resin well known in the art using PET (polyethylene terephthalate), PC (polycarbonate), PMMA (polymethyl methacrylate), COP (cycloolefin polymer), or the like. Alternatively, it may be integrally formed with the third base material 42 by press molding or extrusion molding, or may be formed by an ultraviolet curing molding method in which an ultraviolet solidifying resin is disposed on the incident surface 42a of the third base material 42. good.

In this embodiment, the light diffusing and transmitting layer 45 is made of a transparent resin material so that the total light transmittance is 80% or more and the haze value is 95% or less. This is because the luminance is reduced when the total light transmittance is less than 80%.
The transparent resin material used for the light diffusing and transmitting layer 45 is preferably a thermoplastic resin. For example, polycarbonate resin, acrylic resin, fluorine acrylic resin, silicone acrylic resin, epoxy acrylate resin, polystyrene resin, cycloolefin polymer, Examples include methylstyrene resin, fluorene resin, PET, and polypropylene. In addition, when the light-diffusion transmission layer 45 consists of a thermoplastic resin, you may be extended | stretched at least by the uniaxial direction.
The light diffusing and transmitting layer 45 may contain light diffusing particles, but more preferably does not contain it.

In the present embodiment, the light diffusing and transmitting layer 45 is laminated and integrated with the back lens sheet 41 via a contact adhesive layer 48 made of an adhesive or an adhesive.
The back lens sheet 41 may be integrated with the light diffusion / transmission layer 45 by extrusion molding, or the back lens array 43 including the back lens 44 may be directly formed on the light diffusion / transmission layer 45 by UV molding or the like. It may be molded.

  The light diffusing plate 46 is made of a transparent resin material containing light diffusing particles (light diffusing regions) so that the total light transmittance is 40% or more and 80% or less and the haze value is 98% or more. . This is because when the total light transmittance is less than 40%, the luminance on the screen is greatly reduced, and when it exceeds 80%, the diffusion performance is insufficient. Also, if the haze value is less than 98%, the diffusion performance is still insufficient.

  As the transparent resin material constituting the light diffusion plate 46, a thermoplastic resin is preferable. For example, polycarbonate resin, acrylic resin, fluorine acrylic resin, silicone acrylic resin, epoxy acrylate resin, polystyrene resin, cycloolefin polymer, methyl Examples thereof include styrene resin, fluorene resin, PET, and polypropylene.

  As the light diffusing particles dispersed in the light diffusing plate 46, transparent particles made of an inorganic oxide or a resin can be used. For example, transparent particles made of an inorganic oxide include particles made of silica, alumina or the like. The transparent particles made of resin include acrylic particles, styrene particles, styrene acrylic particles and cross-linked products thereof; melamine-formalin condensate particles; PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxy resin), FEP (tetra Fluoropolymer particles such as fluoroethylene-hexafluoropropylene copolymer), PVDF (polyfluorovinylidene), and ETFE (ethylene-tetrafluoroethylene copolymer); and silicone resin particles. In addition, when the light diffusing plate 46 consists of a thermoplastic resin, you may be extended | stretched by at least 1 axial direction.

  In addition, when the light diffusing plate 46 contains such light diffusing particles, the thickness of the light diffusing plate 46 is preferably 0.1 to 5 mm. When the thickness of the light diffusion plate 46 is 0.1 to 5 mm, optimum diffusion performance and brightness can be obtained. On the other hand, if the thickness is less than 0.1 mm, the diffusion performance is insufficient, and if it exceeds 5 mm, the amount of resin is large and the luminance is reduced due to absorption.

The light diffusing plate 46 and the light diffusing / transmitting layer 45 as described above may be integrally formed by a multilayer extrusion method. For example, after the light diffusing plate 46 and the light diffusing / transmitting layer 45 are separately manufactured, It may be fixed with an adhesive or a pressure sensitive adhesive. When the light diffusing plate 46 and the light diffusing / transmitting layer 45 are integrally formed by a multilayer extrusion method, it is preferable that the light diffusing plate 46 and the light diffusing / transmitting layer 45 are stretched at least in a uniaxial direction.
Alternatively, the light diffusion plate 46 and the light diffusion / transmission layer 45 may be integrated by bonding with an adhesive or an adhesive.

  The light diffusing plate 46, the light diffusing / transmitting layer 45, and the back lens sheet 41 may be integrally formed by a multilayer extrusion method. In this case, the manufacturing process of the light diffusion layer 40 can be simplified and the manufacturing cost can be reduced.

  The first lens sheet 50 is formed in a plate shape, one surface of which forms a light incident surface 52a and the other surface forms a light output surface 52b, and a first substrate 52 which is light transmissive. The first lens array 53 includes a plurality of first lenses 54 disposed on the incident surface 52 a of the base 52.

  The first lens 54 has a cylindrical shape protruding from the emission surface 52 b of the first base material 52, and extends in the depth direction of the paper surface, that is, in the same direction as the extension direction of the light source 11 and the back lens 44. The first lens array 53 is configured by arranging a plurality of the first lenses 54 in a direction orthogonal to the extending direction.

  In addition to the cylindrical shape as shown in FIG. 2, the shape of the first lens 54 is, as shown in FIG. 2, for example, as shown in FIG. 4, a convex-curved first lens top 54a and the first lens top 54a. The distance between the pair of first lens inclined surfaces 54b and 54b facing each other from the first substrate 52 to the first base material 52 is a first lens inclined surface 54b and 54b. It may be formed so as to gradually approach toward the lens top 54a.

  The first base material 52 is formed of a light transmissive transparent resin. Examples of the transparent resin include an acrylic resin, a polystyrene (PS) resin, a methacryl styrene copolymer (MS) resin, and a polycarbonate (PC). A resin, an acrylonitrile styrene copolymer (AS) resin, a cycloolefin polymer (COP), a copolymer containing these as a component, or a mixture of these resins is used.

  The first lens 54 is made of a thermoplastic resin well known in the art using PET (polyethylene terephthalate), PC (polycarbonate), PMMA (polymethyl methacrylate), COP (cycloolefin polymer), or the like. It may be formed integrally with the first base material 52 by the press molding or extrusion molding used, or formed by an ultraviolet curing molding method in which an ultraviolet solidified resin is disposed on the emission surface 52b of the first base material 52. Also good.

In such a light reflection layer (light-shielding layer) 70 provided between the first lens sheet 50 and the light diffusion layer 40, a plurality of opening holes 71 penetrating in the thickness direction are formed. Each opening hole 71 is arranged at a position overlapping the top of the first lens 54 in the thickness direction, and corresponds to each first lens 54 formed in a long shape in the depth direction of the paper in the longitudinal direction. It is formed in an extending slit shape. That is, the plurality of opening holes 71 are arranged in a direction orthogonal to the extending direction at a constant interval, like the plurality of first lenses 54.
The light reflecting layer 70 is formed of, for example, a white pigment.

  In the present embodiment, the light reflecting layer 70 and the light diffusing layer 40 formed on the incident surface 52a of the first base material 52 of the first lens sheet 50 are made of an adhesive, an adhesive, or the like. 55 are laminated and integrated.

  Next, the second lens sheet 60 will be described. The second lens sheet 60 transmits light emitted from the first lens sheet 50 of the optical sheet 30 to the viewer side. In the display device 100 of the present embodiment, three types described below are used. One of the second lens sheets is employed.

  First, the first type of second lens sheet 60A will be described. As shown in FIG. 5, the second lens sheet 60A is formed in a plate shape and has a light-transmitting second surface in which one surface forms a light incident surface 62Aa and the other surface forms a light exit surface 62Ab. The substrate 62A is composed of a second lens array 63A and a third lens array 65A.

  The second lens array 63A has the one direction so that a plurality of second lenses 64A extending along one direction (the depth direction in FIG. 5) of the emission surface 62Ab of the second base material 62A are parallel to each other. Are arranged in an array along a direction orthogonal to the direction.

The second lens 64A, which is a component of the second lens array 63A, is a trapezoidal prism whose section perpendicular to the extending direction of the second lens 64A has an isosceles trapezoidal shape.
The second lens 64A as such a trapezoidal prism exhibits an effect equivalent to that of the triangular prism because the inclined surface constituting the hypotenuse in the cross section is substantially linear. Therefore, since the light condensing effect on the observer side F is increased, the luminance can be improved.

The third lens array 65A is configured by being arranged in an array along the extending direction of the second lens 64A so that the third lenses 66A are parallel to each other. The third lens 66A is formed on the flat surface 64Aa at the top of the second lens 64A, and more specifically, the flat surfaces 64Aa of the plurality of second lenses 64A along the direction orthogonal to the second lens 64A. It extends in a straight line so as to extend discretely.
That is, a third lens array 65A composed of a third lens 66A orthogonal to the second lens 64A is formed on the second lens array 63A composed of the second lens 64A, whereby the second lens array 63A and The arrangement direction with the third lens array 65A is orthogonal.

  In such a second lens sheet 60A, one of the second lens array 63A and the third lens array 65A is parallel to the first lens array 53 of the first lens sheet 50 in the optical sheet 30. The first lens sheet 50 is laminated. As a result, of the second lens array 63A and the third lens array 65A, the one that is not parallel to the first lens array 53 is orthogonal to the first lens array 53.

  Next, the second type of second lens sheet 60B will be described. As shown in FIG. 6, the second lens sheet 60B is formed in a plate shape and has a light-transmitting second surface in which one surface forms a light incident surface 62Ba and the other surface forms a light output surface 62Bb. The substrate 62B is composed of a second lens array 63B and a third lens array 65B.

The second lens array 63B extends along the X direction (one direction) on the emission surface 62Bb of the second base material 62B, and is parallel to each other with an interval in the Y direction that is orthogonal to the X direction. It is formed by a plurality of second lenses 64B arranged.
In the present embodiment, the second lens 64B is a prism lens having a triangular cross-sectional shape in the width direction.

The third lens array 65B is formed by a plurality of third lenses 66B extending along the Y direction (the other direction) on one surface of the second base material 62B and arranged in parallel with each other at an interval in the X direction. Has been. That is, the extending direction of the second lens 64B and the extending direction of the third lens 66B are formed to be orthogonal to each other.
The third lens 66B has a plurality of sub-lenses 67B arranged along the other direction at the valleys of the plurality of second lenses 64B.
Each of the plurality of sub lenses 67B is a prism lens having a triangular cross-sectional shape in the width direction, and the extending direction thereof is the Y direction. Both ends of the sub lens 67B in the extending direction are in contact with the side surfaces of the two second lenses 64B adjacent in the Y direction.

  In such a second lens sheet 60B, one of the second lens array 63B and the third lens array 65B is parallel to the first lens array 53 of the first lens sheet 50 in the optical sheet 30. The first lens sheet 50 is laminated. Thus, the second lens array 63B and the third lens array 65B that are not parallel to the first lens array 53 are orthogonal to the first lens array 53.

  Next, the third type of second lens sheet 60C will be described. As shown in FIG. 7, the second lens sheet 60C is formed in a plate shape and has a light-transmitting second surface in which one surface forms a light incident surface 62Ca and the other surface forms a light exit surface 62Cb. It is composed of a base material 62C and a second lens array 63C.

The second lens array 63C is formed by a plurality of second lenses 64C that extend along one direction on the emission surface 62Cb of the second base material 62C and are arranged in parallel to a direction orthogonal to the one direction. Yes.
The second lens 64C has an external cylindrical lens shape having a flat surface facing the emission surface 62Cb of the second base material 62C and a convex curved surface 65C formed so as to protrude from the emission surface 62Cb. Furthermore, a V-shaped groove 66C extending in the same direction as the extending direction of the second lens 64C is formed at the top of each second lens 64C.

  The second lens sheet 60 </ b> C is laminated on the first lens sheet 50 so that the second lens array 63 </ b> C is parallel to the first lens array 53 of the first lens sheet 50 in the optical sheet 30.

  The second base materials 62A, 62B, and 62C in the three types of second lens sheets 60A, 60B, and 60C are formed of a light-transmitting transparent resin. Examples of the transparent resin include acrylic resin and polystyrene ( PS) resin, methacryl styrene copolymer (MS) resin, polycarbonate (PC) resin, acrylonitrile styrene copolymer (AS) resin, cycloolefin polymer (COP), etc., copolymers comprising these components, or these A mixture of these resins is used.

  The second lens 64A, 64B, 64C and the third lens 66A, 66B are made of the technology using PET (polyethylene terephthalate), PC (polycarbonate), PMMA (polymethyl methacrylate), COP (cycloolefin polymer), etc. It may be integrally formed with the first base material 52 by press molding or extrusion molding using a thermoplastic resin well known in the field, or the emission surfaces 62Ab, 62Bb of the second base materials 62A, 62B, 62C. , 62Cb may be formed by an ultraviolet curing molding method in which an ultraviolet solidified resin is disposed.

  Next, the operation of the optical function member 20 having the above configuration will be described. The backlight unit 80 and the display device 100 adopting the optical functional member 20 are erected so that the first lens sheet 50 and the second lens sheet 60 face the horizontal direction. Further, at this time, the first lens sheet 50 The extending direction of the first lens array 53 is arranged in a direction parallel to the horizontal plane.

Light emitted from the light source 11 of the light source unit 10 enters the back lens sheet 41, is deflected by the back lens array 43, and is diffused with a certain spread angle. Thereafter, the diffused light is transmitted through the light diffusing / transmitting layer 45 while being given a certain amount of light scattering effect, reaches the light diffusion plate 46, and is further diffused by being given a light scattering effect. Reach 70. At this time, the light incident on the opening hole 71 in the light reflecting layer 70 from the light diffusing plate 46 reaches the incident surface 52a of the first base material 52 in the first lens sheet 50 as it is, but the light not incident on the opening hole 71 is. The reflection is repeated between the light reflecting layer 70 and the light diffusing plate 46 or the lamp house 12.
Then, most of the light transmitted through the first base material 52 of the first lens sheet 50 is directed by the first lens array 53 in a direction orthogonal to or close to the exit surface 52b of the first base material 52. Thereby, since the first lens array 53 extends in parallel with the horizontal direction, light in the vertical direction is mainly focused and condensed.

  Thus, the outgoing light, in which the light in the vertical direction is narrowed down by the first lens sheet 50, enters the second lens sheet 60 and is emitted after its optical characteristics are changed. By passing, it is visually recognized by an observer as an image display. Hereinafter, the operation of each of the three types of second lens sheets 60A, 60B, and 60C described above will be described.

  When the second lens sheets 60A, 60B, and 60C shown in FIGS. 5 to 7 are arranged so that the second lens arrays 63A, 63B, and 63B are orthogonal to the first lens array 53, the second lens array 63A, The extending direction of 63B and 63C is along the vertical direction. In this case, the light focused in the vertical direction by the first lens array 53 is focused in the horizontal direction by the second lens arrays 63A, 63B, and 63C, and is collected and emitted.

  In this way, the first lens array 53 and the second lens arrays 63A, 63B, and 63C can narrow the light in two directions, the vertical direction and the horizontal direction, so that the front luminance can be improved. Further, the light in the vertical direction is narrowed by the first lens array 53 of the first lens sheet 50, but the light in the vertical direction is narrowed in the second lens arrays 63A, 63B, and 63C of the second lens sheets 60A, 60B, and 60C. Rather, the light narrowed down in the vertical direction by the first lens sheet is diffused by passing through the second lens sheets 60A, 60B, and 60C. As a result, light passing through the optical function member can be emitted without being excessively narrowed in the vertical direction.

Further, in the second lens sheets 60A and 60B including the third lens arrays 65A and 65B, the light in the vertical direction sufficiently narrowed in the front direction by the first lens array 53 is transmitted by the third lens arrays 65A and 65B. On the contrary, it is diffused to some extent without being narrowed further. That is, generally, when diffused light is incident on the lens array, the light is condensed and narrowed in the front direction, but when light that has already been condensed in the front direction is incident, the light is inclined from the front direction. The light is refracted in the direction and a diffusion effect is given.
Accordingly, it is possible to enlarge the viewing angle at which the luminance is 50% when the vertical half-value angle of light passing through the second lens sheets 60A and 60B, that is, the luminance in the front direction is 100%.

On the other hand, in the second lens sheet 60C in which the V-shaped groove 66C is formed at the top of the second lens 64C, the horizontal generated between the side surface of the V-shaped groove 66C and the air layer interface in the second lens 64C of the second lens sheet 60C. Since light is recycled by total reflection of light in the direction, it is possible to improve the utilization efficiency of light in the horizontal direction and obtain an effect of increasing luminance. In addition, since the surfaces on both sides of the V-shaped groove 66C of the second lens 64C are convex curved surfaces, side lobes can be minimized and a sudden decrease in brightness (cutoff) with respect to the visual field can be mitigated. Fulfills the function of
Furthermore, by recycling the light in the horizontal direction by total reflection, the amount of light in the vertical direction increases because part of the light shifts to light in the vertical direction. As a result, the light in the vertical direction spreads and becomes vertical. It is possible to enlarge the viewing angle at which the luminance is 50% when the half-value angle of the direction, that is, the luminance in the front direction is 100%.

  Thus, according to the optical functional member 20, the backlight unit 80, and the display device 100 according to the present embodiment, the front luminance can be improved by condensing the light in the vertical direction and the horizontal direction, and By emitting the passing light without being narrowed down too much in the vertical direction, it is possible to reduce the luminance change for each viewing angle in the vertical direction.

  The embodiment of the present invention has been described above, but the present invention is not limited to this, and can be appropriately changed without departing from the technical idea of the present invention. For example, in the optical function member 20, the light reflecting layer 70 is not necessarily provided.

In addition, the light diffusion layer 40 in the optical sheet 30 of the optical function member 20 may have another configuration as long as light can be sufficiently diffused. As an example, the optical function member 21 may be a modified example in which the light diffusion layer 40 employs the optical sheet 31 including only the light diffusion plate 46. A modified display device 101 using the optical function member 21 is shown in FIG. In FIG. 8, the same components as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted.
Even when the optical function member 21 of this modification is used, the light that has passed through the light diffusion layer 40 having a single-layer structure including only the light diffusion plate 46 passes through the first lens sheet 50 and the second lens sheet 60. Thus, the front luminance can be improved and the luminance change for each viewing angle in the vertical direction can be reduced.

  An example of a display device (a display device based on the above-described embodiment and modification) employing the optical functional member of the present invention was produced as Examples 1 to 6, and an evaluation test of the physical properties was performed.

(Optical functional member of Example)
As an optical functional member of an example, an optical functional member corresponding to the above-mentioned embodiment and a modification was produced.
First, an optical sheet A corresponding to FIG. 2, that is, a back lens sheet, a light diffusing / transmitting layer, a light diffusing plate, a reflecting layer and a first lens sheet laminated in this order from the back side was prepared. In addition, an optical sheet B corresponding to FIG. 8, that is, an optical sheet B in which a light diffusion plate, a light reflection layer, and a first lens sheet are laminated in this order from the back side was prepared.
Three types of second lens sheets described in the embodiment were produced. The one corresponding to FIG. 5 is the second lens sheet A, the one corresponding to FIG. 6 is the second lens sheet B, and the one corresponding to FIG. 7 is the first lens sheet C.
Then, a total of six optical functional members were produced by combining these optical sheets A and B and the second lens sheets A, B and C. That is, the first lens sheet A is laminated on the optical sheet A as Example 1, the second lens sheet B is laminated on the optical sheet A as Example 2, the second lens sheet is laminated on the optical sheet A as Example 3. A laminate of C, a laminate of the second lens sheet A on the optical sheet B as Example 4, a laminate of the second lens sheet B on the optical sheet B as Example 5, and an optical sheet B as Example 6. Each laminated second lens sheet C was produced.
In these optical functional members, the first lens array in the optical sheets A and B and the second lens array in the second lens sheets A, B, and C were laminated so as to be orthogonal to each other.

(Optical functional member of comparative example)
As Comparative Example 1, an optical functional member consisting only of the optical sheet A was produced.
Further, as Comparative Example 2, an optical functional member in which a cylindrical lens sheet was laminated on the optical sheet A was produced. The cylindrical lens sheet is a lens sheet in which no V-shaped groove is formed in the second lens sheet shown in FIG. 7, that is, a cylindrical lens extending in one direction is aligned in a direction perpendicular to the extending direction. This indicates a lens sheet in which a cylindrical lens array is formed.
Further, an optical functional member composed only of the optical sheet B was produced as Comparative Example 3, and an optical functional member obtained by laminating the above cylindrical lens sheet on the optical sheet B was produced as Comparative Example 4.
In Comparative Examples 2 and 4, in the optical function member, the first lens array in the optical sheets A and B and the cylindrical lens array in the cylindrical lens sheet were stacked so as to be orthogonal to each other.

(Optical functional members of Examples and Comparative Examples)
Display devices incorporating the optical functional members of Examples 1 to 6 and Comparative Examples 1 to 4 were produced. In these display devices, the first lens array of the first lens sheet in the optical sheets A and B is parallel to the horizontal plane, and the second lens sheets A, B, and C stacked on the optical sheets A and B are provided. The lens array of the cylindrical lens sheet was arranged along the vertical direction.

(Measurement / Evaluation)
And the front luminance and the vertical half-value angle of the display image in the display apparatus which mounts the optical function members of Examples 1 to 6 and Comparative Examples 1 to 4 as described above were measured. The vertical half-value angle is a vertical viewing angle at which the luminance is 50% of the front, and means that the luminance change for each vertical viewing angle becomes smaller as the luminance becomes larger.
Table 1 shows the measurement results of Examples 1 to 3 and Comparative Examples 1 and 2 using the optical sheet A. In Table 1, the front luminance is standardized on the basis of Comparative Example 1, and the vertical half-value angle is expressed as a difference from Comparative Example 1.
Table 2 shows the measurement results of Examples 1 to 3 and Comparative Examples 1 and 2 using the optical sheet B. In Table 2, the front luminance is standardized on the basis of Comparative Example 3, and the vertical half-value angle indicates the difference from Comparative Example 3.

As for Examples 1 to 6 in which the second lens sheets A, B and C are laminated on the optical sheets A and B from Table 1 and Table 2, Comparative Examples 1 and 3 of the optical sheets A and B alone and the optical sheets A and B are used. It was confirmed that the half-value angle in the vertical direction was larger than those in Comparative Examples 2 and 4 in which the cylindrical lens sheets were laminated, that is, the luminance change for each viewing angle in the vertical direction was reduced. This was a particularly remarkable result in Examples 1, 2, 4, and 5 using the second lens sheets A and B.
In Examples 1 to 6, in addition to the above effects, it was confirmed that the front luminance was improved when compared with Comparative Examples 1 and 3. In particular, in Examples 3 and 6, it was confirmed that the front luminance was remarkably improved as compared with Comparative Examples 2 and 4.
From the above, it is possible to improve the vertical half-value angle and front luminance by configuring the display device employing the optical functional members of Examples 1 to 6 using the lens sheets A, B, and C. There was found.

It is a longitudinal cross-sectional view of the display apparatus which concerns on embodiment. It is a longitudinal cross-sectional view of the display apparatus which concerns on embodiment. It is a figure explaining the shape of a back lens. It is a figure explaining the shape of a 1st lens. It is a perspective view of the 2nd lens sheet of the 1st type. It is a perspective view of the 2nd type of 2nd lens sheet. It is a perspective view of the 3rd type of 2nd lens sheet. It is a longitudinal cross-sectional view of the display apparatus of a modification. It is a longitudinal cross-sectional view of the display apparatus in which the light guide plate light guide type backlight unit is mounted. It is a longitudinal cross-sectional view of the display apparatus which provided the prism film between the diffusion film and the liquid crystal panel. It is a longitudinal cross-sectional view of the display apparatus provided with the direct type backlight unit. FIG. 4 is a longitudinal sectional view of a display device that includes a lens layer that guides light from a light source to a liquid crystal panel, and a light-shielding portion that has an opening near the focal plane of the lens layer on the light incident side of the lens layer. It is a longitudinal cross-sectional view of the backlight unit provided with the optical sheet in which the reflection layer was provided in the back side of the optical function member. It is a longitudinal cross-sectional view of the liquid crystal display device provided with the backlight unit shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Light source part 11 Light source 12 Lamp house 20 Optical function member 21 Optical function member 30 Optical sheet 31 Optical sheet 40 Light diffusion layer 41 Back surface lens sheet 42 Third base material 42a Incident surface 42b Output surface 43 Back surface lens array 44 Back surface lens 44a Back surface Lens top portion 44b Back lens inclined surface 45 Light diffusion / transmission layer 46 Light diffusion plate 47 Light reflection layer 48 Contact adhesive layer 50 First lens sheet 52 First base material 53 First lens array 54 First lens 54a First lens top portion 54b First 1 lens inclined surface 55 contact adhesive layer 60 second lens sheet 60A second lens sheet 62A second base material 63A second lens array 64A second lens 65A third lens array 66A third lens 60B second lens sheet 62B second base Material 63B Second lens array 64B Second lens 65B Third lens array 6 B Third lens 67B Sub lens 60C Second lens sheet 62C Second base material 63C Second lens array 64C Second lens 65C Curved surface 66C V-shaped groove 70 Light reflecting layer 71 Aperture hole 80 Backlight unit 90 Liquid crystal panel 100 Display device 101 Display device

Claims (27)

An optical functional member that converts the optical characteristics of light from a light source arranged on the incident surface side and emits the light from the exit surface,
A light diffusion layer disposed on the incident surface side for diffusing light from the light source;
A light-transmitting first base material that is laminated on the light exit surface side of the light diffusion layer and has a plate shape, and extends along the surface of the first base material on the light output surface side and is disposed in parallel with each other A first lens sheet comprising a first lens array composed of a plurality of first lenses,
A light-transmitting second base material that is laminated on the output surface side of the first lens sheet and forms a plate shape, along the surface of the second base material on the output surface side, and the first lens And a second lens sheet that includes a second lens array that includes a plurality of second lenses that extend in a direction orthogonal to each other and are arranged in parallel to each other. The second lens sheet further includes a third lens array including a plurality of third lenses extending along a direction orthogonal to the second lens and arranged in parallel with each other;
The second lens sheet is laminated on the first lens sheet so that one of the second lens and the third lens is parallel to the first lens. Item 4. The optical functional member according to Item 1.   The optical function member according to claim 2, wherein each of the third lenses extends discretely over the tops of the plurality of second lenses.   Each of the third lenses is extended along the surface on the emission surface side of the second base material, and a plurality of lower heights than the first lens are formed in valleys of the plurality of first lenses. The optical functional member according to claim 2, wherein a sub lens is formed.   Each of the second lenses has a convex curved surface formed so as to protrude from the surface on the emission surface side of the second base material, and has a V-shape extending in the extending direction of the second lens at the top. The optical functional member according to claim 1, wherein a groove is formed. The first lens includes a convex-curved first lens top and a pair of first lens inclined surfaces extending from the first lens top to the first base,
The distance between the pair of opposing first lens inclined surfaces is formed so as to gradually approach from the first base toward the top of the first lens. The optical function member as described in any one of Claims. The light diffusion layer is
A rear lens sheet comprising a rear lens array composed of a plate-shaped light-transmitting third base material, and a plurality of rear surface lenses arranged on the incident surface side surface of the third base material;
A light diffusing and transmitting layer that is laminated on the exit surface side of the back lens sheet and transmits light while diffusing;
The optical functional member according to any one of claims 1 to 6, further comprising a light diffusing plate that is laminated on the light exit surface side of the light diffusing and transmitting layer and has a substantially plate shape to diffuse light. . The back lens extends along the surface on the incident surface side of the third substrate and is arranged in parallel with each other, and each of the back lenses has a convex-curved back lens top and the back lens top A pair of back surface lens inclined surfaces extending from the third base material to the third base material,
8. The optical function according to claim 7, wherein a distance between the pair of opposed rear surface lens inclined surfaces is formed so as to gradually approach from the third base material toward the top of the rear surface lens. Element.   The optical functional member according to claim 7, wherein the back lens is a plurality of triangular prisms that extend along the incident surface side surface of the third base material and are arranged in parallel to each other. .   The back lens is a micro lens arranged in a matrix on the incident surface side surface of the third base material, and the back lens array is a micro lens array. Optical functional member.   The optical function member according to claim 7, wherein the light diffusion plate and the light diffusion transmission layer are integrally formed by a multilayer extrusion method.   12. The optical functional member according to claim 11, wherein the light diffusing plate and the light diffusing and transmitting layer are stretched in at least one axial direction when integrally formed by a multilayer extrusion method.   11. The optical function member according to claim 7, wherein the light diffusion plate and the light diffusion / transmission layer are bonded and integrated by an adhesive or an adhesive.   The optical functional member according to any one of claims 7 to 13, wherein the back lens is made of a transparent resin having a total light transmittance of 85% or more.   The optical function member according to any one of claims 7 to 14, wherein the light diffusion transmission layer is a transparent resin having a total light transmittance of 80% or more and a haze value of 95% or less.   The optical function member according to claim 7, wherein the light diffusing and transmitting layer does not contain light diffusing particles.   The optical functional member according to any one of claims 7 to 16, wherein the light diffusing and transmitting layer is made of a thermoplastic resin.   The optical functional member according to claim 7, wherein the light diffusing and transmitting layer is stretched in at least one axial direction.   The optical function member according to claim 1, wherein the light diffusion layer is made of a light diffusion plate.   20. The light diffusion plate according to claim 7, wherein a light diffusion region is dispersed in a transparent resin, and has a total light transmittance of 40% to 80% and a haze value of 98% or more. The optical functional member according to one item.   21. The optical function member according to claim 7, wherein the light diffusion region is a light diffusion particle, and the thickness of the light diffusion layer is 0.1 to 5 mm.   The optical function member according to any one of claims 7 to 21, wherein the light diffusion plate is extended in at least one axial direction. Between the light diffusion layer and the first lens sheet, a light shielding layer that blocks light is provided,
The light-shielding layer is formed with a plurality of light transmission apertures that penetrate in the thickness direction and extend in the longitudinal direction of the first lens.
The optical function member according to any one of claims 1 to 22, wherein each opening hole is arranged at a position overlapping with a top portion of the first lens in the thickness direction.   The optical functional member according to any one of claims 1 to 23, wherein the first lens sheet and the light diffusion layer are laminated and integrated by being bonded together with an adhesive or an adhesive. .   A backlight unit comprising: the optical functional member according to claim 1; and a light source disposed on the incident surface side of the optical functional member. A backlight unit according to claim 25;
A display device comprising: an image display element that displays an image by light irradiation from the backlight unit. 27. The display device according to claim 26, wherein the image display element is a liquid crystal display element.

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