JP2010118240A - Optical member, backlight unit, and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical member, a backlight unit and a display device, capable of effectively removing luminance deviation owing to a light source. <P>SOLUTION: In the optical member 20 emitting light from a plurality of linear light sources 11 arranged opposed along one sheet face 21a of a sheet-shaped base material 21 transmitting light in a front face direction F from the other sheet face 21b by converting its optical property, diffusion-reflecting bodies 22 transmitting a part of the light emitted from the linear light sources 11 in the front face direction F and diffusion-reflecting the other light are arranged each at a position opposed to the linear light sources 11 in the one sheet face 21a, and optical deflection elements 23 for converging the light emitted from the linear light source 11 slanting from the front face direction into the front face direction are arranged in entire regions between the diffusion-reflecting bodies 22 in the one sheet face 21a. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical member used for illumination light path control in a direct-type backlight unit for a display mainly using a liquid crystal display element, a backlight unit using the optical member, and a display device.

  In recent years, liquid crystal display devices (LCD) using liquid crystal panels have been used in image display means for notebook personal computers and personal computer displays in the OA field, information terminal equipment, etc., information display means for information appliances such as large-screen TVs, and more Has been used in various fields as an image display means of a mobile phone or a personal digital assistant (PDA).

In a display typified by a liquid crystal display device (LCD), a type having a built-in light source necessary for recognizing information to be provided has been widespread.
Such a liquid crystal display device is a transmissive type, and a light source is provided on the back side of the liquid crystal panel, and a surface light source device that irradiates the liquid crystal panel by converting light from the light source into surface light emission, a so-called backlight is provided. It has been adopted.

  The backlight system is roughly divided by attaching a light source such as a cold cathode fluorescent tube (CCFT) along the side edge of a flat light guide plate made of acrylic resin or the like having excellent light transmittance. There are a light guide plate light guide method (edge light method) that multi-reflects light from the light guide plate and a direct type method in which a light source is arranged on the back surface of the liquid crystal panel without using the light guide plate.

Recently, for small liquid crystal display devices with a screen size of 20 inches or less used for notebook personal computers and portable information terminals, the adoption of an edge light system that can achieve low power consumption and is easy to thin, has become mainstream. In medium to large liquid crystal display devices having a screen size of 20 inches or more, the direct type is the mainstream.
In a battery-powered device such as a laptop computer, the power consumed by the light source occupies a substantial portion of the power consumed by the entire battery-powered device. Thus, reducing the total power required to provide a given brightness increases battery life, which is particularly desirable for battery powered devices.

  Further, a liquid crystal display device of 20 inches or more is required to be thinner, have a low viewing angle dependency, have high luminance, and have low power consumption. Is also required to deal with its realization.

  In a direct type backlight in which a plurality of cold cathode fluorescent lamps are arranged in parallel, a cold cathode fluorescent lamp (CCFT) or an LED (Light Emitting Diode) as a light source passes through a diffusion plate that diffuses emitted light, and the emitted light source Since the shape is easily visually recognized, a resin plate having a very strong light scattering property is used as the diffusion plate. This diffuser plate usually needs a thickness of about 1 mm to 3 mm in order to give strong diffusibility, and because of the thickness, there is not a little light absorption, the light quantity from the light source is reduced, and the liquid crystal display is displayed. There is a problem of darkening.

  There has also been proposed a method for improving the diffusion performance of a diffusion plate by forming a convex lens such as a lenticular lens on the diffusion plate (Patent Documents 1 to 3). In the case of an ordinary flat plate-shaped diffusion plate, the light intensity incident on the gap portion of the light source is lower than the light intensity incident directly above the light source, so that light source unevenness is visually recognized. When using a diffuser plate with a convex lens on the light incident surface side, the light incident directly above the light source is diffused by the lens, and the light incident on the gap portion of the light source rises in the front direction by total internal reflection of the lens. Therefore, it is possible to alleviate the light source unevenness that has conventionally occurred.

However, when the distance between the light source and the diffusion plate is narrow or when the distance between the light sources is large, the difference between the light intensity incident directly above the light source and the light intensity incident on the gap between the light sources becomes very large. It is difficult to completely eliminate the unevenness of the light source using only the lens formed on the diffusion plate.
JP 2007-103321 A JP 2007-12517 A JP 2006-195276 A

  However, in the above prior art, when the distance between the light source and the diffusion plate is narrow, or when the distance between the light sources is separated, the light intensity of the light incident directly above the light source and the light light incident on the gap between the light sources. Since the difference in intensity becomes very large, it is difficult to completely remove the luminance unevenness caused by the light source using only the lens molded on the diffusion plate.

  This invention is made in view of such a subject, and it aims at providing the optical member, backlight unit, and display apparatus which can remove the brightness nonuniformity by a light source more effectively.

In order to solve the above problems, the present invention proposes the following means.
That is, the optical member according to the present invention converts light from a plurality of light sources arranged opposite to each other along one sheet surface of a sheet-like substrate that transmits light, and converts the optical characteristics thereof to the other sheet surface. Is an optical member that emits in the front direction from the light source at a position facing the plurality of light sources on the one sheet surface, and is projected in the front direction from the light source. Diffuse reflectors that transmit part of the light and diffusely reflect other light are respectively disposed, and a plurality of convex unit lenses are arranged on the entire surface of the one sheet surface between the diffuse reflectors. And a light deflecting element that collects light emitted from the light source with an inclination from the front direction in the front direction.

When a plurality of light sources are arranged, generally, a spot with a high light intensity appears in the front direction when viewed from the light source, that is, a position facing the light source, and a position inclined from the front direction when viewed from the light source, That is, a spot with low light intensity appears at a corresponding position between adjacent light sources.
Here, in the optical member according to the present invention, a diffuse reflector is provided at a position facing the light source, that is, a position in the front direction as viewed from the light source, and the diffuse reflector reflects the light from the light source in the front direction. Only part of the light to be transmitted is transmitted. In addition, a light deflecting element composed of a plurality of unit lenses is laid between the diffuse reflectors, whereby light incident on the light deflecting element at an angle is condensed in the front direction.
Therefore, a spot having a high light intensity is extinguished by the diffuse reflector, and the brightness between the light source and the light source can be increased by the light deflecting element. Can be obtained.

  Furthermore, in the optical member according to the present invention, the diffuse reflector protrudes toward the light source from the unit lens and has a flat top, and a diffuser plate having a flat plate shape includes the base material and It is provided in parallel and in contact with each of the flat surfaces.

When the top part of the unit lens constituting the light deflection element is in contact with the diffusion plate, the contact surface between the light deflection element and the diffusion plate is visually recognized as bright bright lines and bright spots. This is because the top surface of the unit lens in contact with the diffuser plate is crushed so that a contact surface is formed between the two, and the light incident perpendicularly to the contact surface, that is, the light incident on the top portion of the unit lens is not refracted. While proceeding to the front direction as it is, the light intensity in the front direction is increased, while the light incident on the slope of the unit lens is refracted to change the traveling direction to an oblique direction, and the light intensity in the direction inclined from the front direction is increased. Based on being weakened. That is, when the difference in light intensity between the front direction and the tilt direction increases, a bright and dark pattern appears and the bright lines and bright spots are visually recognized.
In this respect, in the optical member according to the present invention, since the diffuser plate is in contact with the top of the diffuse reflector that protrudes from the unit lens, the diffuser plate and the unit lens are not in contact with each other. A gap can be formed. As a result, no contact surface is formed between the diffuser plate and the top of the unit lens, so that light incident on the top of the unit lens is appropriately refracted and dispersed, and is visually recognized as bright lines and bright spots. This can be prevented.

  In the optical member according to the present invention, a height difference ΔH from the one sheet surface of the diffuse reflector and the unit lens is set in a range of 10 nm to 150 nm.

When ΔH is less than 10 nm, the height of the two is too small, and thus the reflective layer adheres to the unit lens when the diffusive reflector is molded, so that the characteristics of the unit lens are deteriorated. On the other hand, when ΔH exceeds 150 nm, the light entering the side surface of the diffuse reflector is inclined and increases. Therefore, when viewed from the direction inclined from the front direction of the optical member, the light is reflected at the position of the diffuse reflector. This is not preferable because a linear spot with high intensity is visually recognized.
In consideration of this point, in the optical member according to the present invention, ΔH is set in the range of 10 nm to 150 nm, and thus the above-described disadvantage does not occur.

  In the optical member according to the present invention, the diffuse reflectors extend in a one-dimensional direction on the one sheet surface so that the diffuse reflectors are parallel to each other, and the unit lens is parallel to the diffuse reflector. It extends in a one-dimensional direction. In this optical member, the unit lens is preferably either a prism or a lenticular lens.

Further, in the optical member according to the present invention, the diffuse reflectors extend in a one-dimensional direction on the one sheet surface so that the diffuse reflectors are parallel to each other, and the unit lens is on the one sheet surface. A plurality may be arranged in a two-dimensional direction.
Further, in the optical member according to the present invention, the diffuse reflectors are arranged in a two-dimensional direction at intervals on the one sheet surface, and the unit lenses are two-dimensionally arranged on the one sheet surface. A plurality may be arranged in the direction.
In these optical members, the unit lens is preferably a microlens, a triangular pyramid lens, or a quadrangular pyramid lens.

  The optical member according to the present invention is characterized in that light scattering particles are dispersed and mixed in the base material. As a result, the light that has passed through the diffuse reflector and the light deflection element can be diffused, so that display characteristics with higher luminance uniformity can be obtained.

  Further, in the optical member according to the present invention, the diffuse reflector is configured by providing a light reflecting layer on a surface of a light-transmitting base formed in a convex shape from the one sheet surface toward the light source. It is characterized by being. Thereby, it is possible to easily obtain the characteristics of the diffuse reflector such that only a part of the light emitted from the light source is transmitted and the other light is reflected.

  The backlight unit according to the present invention includes any one of the optical members described above and a light source unit in which the light sources are respectively arranged at positions facing the diffuse reflector.

  According to the backlight unit having such a feature, the use of the optical member eliminates a spot having a high light intensity by the diffuse reflector, and the brightness between the light sources by the light deflection element. Therefore, it is possible to emit light with high luminance uniformity without light source unevenness as a whole.

  Further, the backlight unit according to the present invention emits light on the other sheet surface side of the optical member by controlling at least one of an emission direction, an emission range, and a luminance distribution of light emitted from the other sheet surface. It is preferable that an optical sheet is provided.

  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.

  Since the display device having such a feature includes the backlight unit, it is possible to realize excellent display quality without uneven brightness.

  According to the optical member, the backlight unit, and the display device of the present invention, the spot having a strong light intensity is extinguished by the diffuse reflector, and the brightness between the light source and the light source is increased by the light deflection element. The luminance unevenness due to can be more effectively removed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, about the optical 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 first 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. In this liquid crystal display device, an image is displayed by emitting display light whose display is controlled by an image signal from the liquid crystal panel 90 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.
In the present embodiment, 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. The light source unit 10, the optical member 20, and the two layers of optical sheets 50 are laminated in this order. It consists of

  In the present embodiment, the light source unit 10 includes a plurality of linear light sources 11 having a cylindrical shape extending in the depth direction of the paper, arranged at a constant pitch so as to be parallel to each other. A direct type system is adopted in which the back side and the side are surrounded by the lamp house 12.

As the linear 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.

The light emitted from the light source unit 10 for such a backlight is immediately adjacent to the linear light source 11, that is, a portion in the front direction as viewed from the linear light source 11 becomes bright and a spot having a high light intensity appears, but is adjacent to the light source unit 10. The linear light source 11 is darkened. For this reason, a problem arises in that the shape (lamp image) of each linear light source 11 is visually recognized by an observer in the front direction and light source unevenness occurs.
However, since the backlight unit 80 in the present embodiment includes the optical member 20 as will be described later, when the direct type is used as the backlight unit 80, the problem of visibility due to the light source unevenness as described above is caused. Can be suppressed.

  The optical member 20 includes a diffuse reflector 22 and one of the two sheet surfaces 21a and 21b of the base material 21 formed in a sheet shape as shown in FIGS. An optical deflection element 23 is provided, and a diffusion plate 27 is laminated on the back side of the diffuse reflection and optical deflection element 23.

  The base material 21 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, a polycarbonate (PC) resin, and acrylonitrile. A styrene copolymer (AS) resin, a cycloolefin polymer (COP), a copolymer containing these as a component, or a mixture of these resins is used.

  The diffusive reflector 22 extends in the depth direction of the drawing sheet of FIG. 1 so as to be parallel to the linear light sources 11 at positions facing the linear light sources 11 on the sheet surface 21a of the base material 21. Thus, it is provided so as to form a convex shape that protrudes from the sheet surface 21 a toward the linear light source 11. Thereby, as shown in FIG. 3, the plurality of diffuse reflectors 22 are arranged parallel to each other at a constant interval, as in the linear light source 11, and as shown in FIG. Are arranged in the front direction F of each linear light source 11 so as to have a one-to-one relationship with respect to each other.

As shown in FIG. 2, the diffuse reflector 22 includes a bottom surface 22a in contact with the sheet surface 21a, a flat surface 22b parallel to the bottom surface 22a, and a pair of inclined surfaces 22c connecting the bottom surface 22a and the flat surface 22b. , 22c, that is, the diffuse reflectors 22 in the cross-sectional side view are arranged such that the bottom surface 22a is the bottom bottom, the flat surface 22b is the top bottom, and the inclined surfaces 22c and 22c are from the bottom surface 22a toward the flat surface 22b. It has an isosceles trapezoidal shape with an approaching hypotenuse.
The plurality of diffuse reflectors 22 all have the same shape, and the flat surfaces 22 b of the respective diffuse reflectors 22 are all arranged on the same plane parallel to the base material 21.

  The diffuse reflector 22 is formed by providing a light reflecting layer on the surface of a base portion having a convex structure with a flat top. This base portion is provided by a method of integrally molding with the base material 21 by press molding or extrusion molding using a thermoplastic resin, or a method of separately molding by an ultraviolet curing molding method using an ultraviolet curable resin. The light reflecting layer is provided on the surface of the base by printing or transferring ink mixed with a white pigment such as titanium dioxide, barium sulfate, or magnesium oxide on the top of the base.

  The light deflection element 23 is provided over the entire surface of the sheet surface 21a so as to fill the region between the diffuse reflectors 22. More specifically, the light deflection element 23 is configured by arranging a plurality of convex unit lenses 24 protruding from the sheet surface 21a. In the present embodiment, the diffuse reflector 22 is used as the unit lens 24. As in FIG. 1, a prism 25 extending in the depth direction of FIG. 1 is employed. As a result, as shown in FIG. 3, the plurality of diffuse reflectors 22 and prisms 25 are arranged in stripes.

As shown in FIG. 2, the prism 25 includes a bottom surface 25a in contact with the sheet surface 21a and a pair of inclined surfaces 25b, 25b. That is, the prism 25 has a bottom surface 25a as a base in a side sectional view. It forms an isosceles triangle with the slopes 25b and 25b as hypotenuses.
The plurality of prisms 25 all have the same shape, and the apex portions 25c corresponding to the vertices of the isosceles triangle in a side sectional view are all arranged on the same plane parallel to the base material 21.

  The light deflection element 23 uses a thermoplastic resin well known in the art using PET (polyethylene terephthalate), PC (polycarbonate), PMMA (polymethyl methacrylate), COP (cycloolefin polymer), or the like. The substrate 21 may be integrally formed with the substrate 21 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 sheet surface 21a of the substrate 21.

  Further, in the present embodiment, the diffuse reflector 22 protrudes to the back side with respect to the unit lens 24 (prism 25) constituting the light deflection element 23. That is, in the side sectional view in FIG. 2, the height of the diffuse reflector 22 that is the distance between the bottom surface 22a and the flat surface 22b in the diffuse reflector 22 is H1, and the prism that is the distance between the bottom surface 25a and the top portion 25c in the prism 25. When the height of 25 is H2, the relationship of H1> H2 is established. Further, in the present embodiment, the height difference ΔH between the diffuse reflector 22 and the unit lens 24 from the one sheet surface 21a is set in the range of 10 nm to 150 nm.

  Then, on the further back side of the diffuse reflector 22 and the light deflection element 23 arranged on the back side of the base material 21 in this way, a flat plate-shaped diffusion plate 27 is laminated so as to become the base material 21. Has been. By laminating in this way, the light exit surface 27b opposite to the light incident surface 27a facing the back side of the diffuser plate 27 protrudes to the back side of the unit lens 24 and the flat surface 22b of the diffuse reflector 22 is projected. Abut each of the. In addition, an air layer 28 is formed as a gap between the incident surface 27 a and the prism 25.

  The diffusion plate 27 is configured by dispersing light scattering particles in a transparent resin. As this transparent resin, the same transparent resin and transparent resin as the base material 21 are used.

  Further, as the light scattering particles dispersed and mixed in the transparent resin, particles made of inorganic fine particles or organic fine particles are used. Examples include acrylic particles, styrene particles, styrene acrylic particles and cross-linked products thereof, melamine-formalin condensate particles, polyurethane particles, polyether particles, polyamide particles, polyester particles, silicone particles, fluorine. Particles, copolymers of these, clay compound particles such as smectite, kaolinite, talc, inorganic oxide particles such as silica, titanium dioxide, alumina, silica alumina, zirconia, zinc oxide, barium oxide, strontium oxide, calcium carbonate , Barium carbonate, barium chloride, barium sulfate, barium nitrate, barium hydroxide, aluminum hydroxide, strontium carbonate, strontium chloride, strontium sulfate, strontium nitrate, strontium hydroxide, glass particles, etc. .

  The diffusion plate 27 made of such a material can be manufactured by forming it into a plate shape by an extrusion method. The extrusion method is a method in which a thermoplastic resin is heated and melted with an extruder, extruded from a T-die, and formed into a plate shape or a sheet shape.

Two optical sheets 50 are laminated so as to face the sheet surface 21b of the base member 21 in the optical member 20, and at least the light emission direction, the emission range, and the luminance distribution emitted from the sheet surface 21b. One is controlled and ejected. As the optical sheet 50, for example, a sheet including a light-transmitting film formed in a film shape and having a light transmission property, and a lens array integrally provided on an emission surface of the light-transmitting film is used. .
In the present embodiment, the two optical sheets 50 are stacked, but the present invention is not limited to this, and may be one or three or more. When desired optical characteristics can be obtained by the optical sheet 50, the backlight unit 80 and the display device 100 may be configured without providing the optical sheet 50.

  Next, operations of the optical sheet 50, the backlight unit 80, and the display device 100 including the diffusion plate 27 will be described.

The light emitted from each linear light source 11 of the light source unit 10 toward the optical sheet 50 is incident on the incident surface 27a of the diffusion plate 27 disposed on the backmost side of the optical member 20, and the inside of the diffusion plate 27 After being given a certain scattering effect at, the light is emitted from the exit surface 27b.
FIG. 4 is a diagram for explaining the optical path of light incident on the diffusion plate 27. I1 is a light intensity distribution at a position facing each linear light source 11 on the incident surface 27a of the diffusing plate 27 (a position in the front direction F when viewed from the linear light source 11), and J2 is adjacent to the incident surface 27a of the diffusing plate 27. 2 is a light intensity distribution at a position (a position where the light emitted from the linear light source 11 is inclined with respect to the front direction F) opposed to an intermediate position between the two linear light sources 11 and 11.

  When comparing the light intensity on the incident surface 27a side of the diffuser plate 27, the light intensity irradiated to the position facing the linear light source 11 is strong as shown in FIG. 4, and the linear light source 11 and the linear light source 11 Since the light intensity irradiated during the period becomes weak, I1 becomes a spot having a high light intensity and J2 becomes a spot having a low light intensity. Further, although the light incident on the diffusion plate 27 is diffused to some extent in the diffusion plate 27, it is emitted from the emission surface 27b of the diffusion plate 27 with the same light intensity distribution as that of the incident surface 27a.

  Here, when it is assumed that the optical member 20 of the present embodiment is composed only of the diffusion plate 27, the light emitted from each linear light source 11 has a certain scattering effect by passing through the diffusion plate 27. Although given, as described above, I1 becomes a spot having a high light intensity and J1 becomes a spot having a low light intensity, so that it is visually recognized as light source unevenness when viewed from the observer side. This is particularly noticeable when the distance D1 between the diffusing plate 27 and the linear light source 11 is reduced, or when the distance D2 between the linear light source 11 and the linear light source 11 is increased, and the light source unevenness is strongly recognized. End up.

  In this regard, in the optical member 20 of the present embodiment, since the diffuse reflector 22 and the light deflection element 23 are provided on the exit surface 27b side of the diffuser plate 27, the above light source unevenness can be removed. it can.

That is, as shown in FIG. 5, the light L1 emitted from the spot I1 having a high light intensity on the incident surface 27a of the diffusion plate 27 and traveling in the front direction F is incident on the semi-transmissive diffuse reflector 22 and diffused. It is dispersed into the reflected light L1a and the transmitted light L1b whose intensity has been reduced. The diffusely reflected light L1a is reflected and reused by the lamp house 12 covering the periphery of the linear light source 11.
On the other hand, the light L2 that travels with an inclination from the front direction F from the spot I1 having a high light intensity is emitted from the diffusion plate 27 and then enters the unit lens 24 (prism 25) of the light deflection element 23. It is raised in the front direction F by total internal reflection at the slope 25b.

  In this way, only a part of the light emitted from the linear light source 11 in the front direction F by the diffuse reflector 22 provided at the position facing the linear light source 11, that is, at the position in the front direction F when viewed from the light source. Is transmitted and the spot having a high light intensity is extinguished, and the light incident on the unit lens 24 of the light deflecting element 23 in an inclined manner is condensed in the front direction so that the linear light source 11 and the linear light source 11 are linear. By increasing the brightness with respect to the light source 11, it is possible to emit light having high luminance uniformity without light source unevenness from the sheet surface 21 b as a whole.

  Here, for example, as shown in FIG. 6, when the top portion 25 c of the unit lens 24 (prism 25) constituting the light deflection element 23 and the exit surface 27 b of the diffusion plate 27 are in contact, these unit lenses 24 ( The contact surface between the prism 25) and the diffusion plate 27 is visually recognized as a bright bright line or bright spot. This is because the light incident perpendicularly to the contact surface, that is, the light incident on the top 25c of the unit lens 24 (prism 25) is not refracted and proceeds in the front direction F as it is, and the light intensity in the front direction F This is based on the fact that the light incident on the inclined surface 25b of the unit lens 24 (prism 25) is refracted to change the traveling direction to an oblique direction, and the light intensity in the direction inclined from the front direction F is weakened. That is, when the difference in light intensity between the front direction F and the tilt direction increases, a bright and dark pattern appears and the bright lines and bright spots are visually recognized.

  In this respect, in the optical member 20 of the present embodiment, the diffuser plate 27 is in contact with the flat surface 22b of the diffuse reflector 22 protruding from the unit lens 24 (prism 25). The lens 24 (prism 25) is not in contact with each other, and an air layer 28 is formed by a gap between them. As a result, no contact surface is formed between the diffuser plate 26 and the top of the unit lens 24 (prism 25), so that the light incident on the top of the unit lens 24 is appropriately refracted and dispersed, resulting in a bright line. , It can be prevented from being visually recognized as a bright spot.

Further, when the height difference ΔH from one sheet surface 21a of the diffuse reflector 22 and the unit lens 24 (prism 25) is less than 10 nm, the height of the two is too small, and thus the diffuse reflector 22 is molded. In this case, since the reflection layer adheres to the unit lens 24 (prism 25), the characteristics of the unit lens 24 (prism 25) are deteriorated. On the other hand, when ΔH exceeds 150 nm, light entering the inclined surface 22c that is the side surface of the diffuse reflector 22 is increased, so that when viewed from a direction inclined from the front direction F, the diffuse reflector 22 is seen. Since a linear spot with a strong light intensity is visually recognized at the position of.
In the optical member 20 of the present embodiment, in consideration of this point, ΔH is set in a range of 10 nm to 150 nm, and thus the above-described disadvantage does not occur.

  And the light with high luminance uniformity (symbol K shown in FIG. 1) emitted from the other sheet surface 21b of the base member 21 in the optical member 20 passes through the optical sheets 50 and 50, so that the emission direction thereof, At least one of the emission range and the luminance distribution is controlled so as to be optimal according to the usage, and is emitted to the liquid crystal panel 90. Thereafter, the light is appropriately polarized by passing through the polarizing plate 92, and then light is transmitted as display light from the predetermined pixel region via the liquid crystal cell 91 and the polarizing plate 93, and an image having a certain viewing angle is displayed. Is done.

  Thus, according to the backlight unit 80 of the present embodiment, the use of the optical member 20 causes the diffuse reflector 22 to extinguish a spot having a high light intensity, and causes the light deflecting element 23 to make a line. Since the brightness between the linear light source 11 and the linear light source 11 can be increased, it is possible to emit light with high luminance uniformity without light source unevenness as a whole.

  In addition, according to the display device 100 of the present embodiment, by providing the backlight unit 80, it is possible to realize excellent display quality without luminance unevenness.

Furthermore, since the light source unevenness can be removed by the optical member 20, the distance D1 between the diffusion plate 27 and the linear light source 11 in FIG. 4 can be reduced, and the distance between the linear light source 11 and the linear light source 11 can be reduced. D2 can be increased. Therefore, it is possible to provide the backlight unit 80 and the display device 100 that can be thinned and can save power by reducing the number of the linear light sources 11.

In the present embodiment, a prism 25 extending in a one-dimensional direction is adopted as the unit lens 24 constituting the light deflection element 23 in the same manner as the diffuse reflector 22, but the present invention is not limited to this. As shown in FIG. 7, a cylindrical lens 26 extending in a one-dimensional direction similarly to the diffuse reflector 22 may be used.
Further, the unit lenses 24 may be microlenses 29 arranged in a two-dimensional direction on one sheet surface 21a of the base member 21, as shown in FIG. Further, instead of the micro lens 29, for example, a plurality of triangular pyramid lenses or quadrangular pyramid lenses may be arranged in a two-dimensional direction.
Also in this case, the light deflection element 23 capable of increasing the brightness between the linear light source 11 and the linear light source 11 can be configured as in the case where the prism 25 is employed as the unit lens 24. it can.

Next, a display device 200 according to a second embodiment of the present invention will be described. FIG. 9 is a schematic cross-sectional view showing a schematic configuration of a display device 200 according to the second embodiment. The display device 200 of the second embodiment is different from the display device 100 of the first embodiment in the configuration of the light source unit 10 and the optical member 20.
9, the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the light source unit 10 according to the present embodiment, the point light sources 13 that can emit light radially are arranged in a two-dimensional matrix in a matrix shape, and the back side and the side surface side of the thus arranged point light sources 13 are the lamp house 12. A direct type system configured by being surrounded by a circle is adopted.

As the point light source 13, it is preferable to employ a light emitting diode (LED). When forming this light emitting diode, for example, a method of emitting white light by combining light emitting elements emitting light of a single color is generally used. In mobile devices such as mobile phones, there is a white LED that emits pseudo white light by mounting a yellow phosphor on a light emitting element that emits blue light. In addition, the point light source 13 is not limited to the above-described one, and may be one in which at least one other phosphor is mounted on one single-color light-emitting element, for example, as provided in a mobile device. . Furthermore, the point light source 13 may be a normal fluorescent lamp, a halogen lamp, a semiconductor laser, or the like. Furthermore, the point light source is not limited to the above-described one, and it may be a single monochromatic LED element covered with at least one kind of phosphor.

  The diffuse reflector 32 in the optical member 20 in the present embodiment is a convex shape that protrudes from the sheet surface 21 a toward the linear light source 11 at each of the positions facing the plurality of point light sources 13 on the sheet surface 21 a of the substrate 21. It is provided to make. Thereby, as shown in FIG. 10, the diffuse reflector 32 is arranged in a two-dimensional matrix in the same manner as the point light source 13, and each point has a one-to-one relationship with the point light source 13. It is located immediately above the light source 13.

Such a diffuse reflector 32 includes a bottom surface 32a that is in contact with the sheet surface 21a and has a rectangular shape, a flat surface 32b that is also rectangular and is disposed in parallel with the bottom surface 32a, and the bottom surface 32a and the flat surface 32b. In other words, the diffuse reflector 32 has a quadrangular frustum shape with the flat surface 32b as the upper bottom surface.
The plurality of diffuse reflectors 32 all have the same shape, and the flat surfaces 32 b of the respective diffuse reflectors 32 are all arranged on the same plane parallel to the base material 21.

  The light deflection element 33 is provided over the entire surface of the sheet surface 21a so as to fill the region between the diffuse reflectors 32. More specifically, the light deflection element 33 is configured by arranging a plurality of convex unit lenses 34 protruding from the sheet surface 21a. In the present embodiment, the micro lens 35 is employed as the unit lens 34. Has been. Thereby, as shown in FIG. 10, a plurality of diffuse reflectors 32 and microlenses 35 are arranged in a matrix. Note that the unit lens 34 that can be arranged in a matrix like the microlens 35 may employ a triangular pyramid lens or a quadrangular pyramid lens, for example.

Also in the second embodiment, similarly to the first embodiment, the diffuse reflector 32 protrudes to the back side from the unit lens 34 (microlens 35) constituting the light deflection element 33, and one of these sheets The height difference ΔH from the surface 21a is set in the range of 10 nm to 150 nm.
The optical member 20 is configured by laminating the diffusing plate 27 so that the emission surface 27b is in contact with each of the flat surfaces 32b of the diffusing reflector 32.

  In the optical member 20 of the second embodiment, as in the first embodiment, one of the light emitted from the linear light source 11 in the front direction F by the diffuse reflector 32 provided at a position facing the point light source 13. A spot having a high light intensity is extinguished through only a portion, and light incident on the unit lens 34 (microlens 35) of the light deflection element 33 at an angle is condensed in the front direction. By increasing the brightness between the light source 13 and the point light source 13, it is possible to emit light with high luminance uniformity without light source unevenness as a whole from the sheet surface 21b.

As described above, the optical member 20, the backlight unit 80, and the display devices 100 and 200 according to the embodiment of the present invention have been described. However, the present invention is not limited thereto, and may be appropriately selected without departing from the technical idea of the present invention. It can be changed.
For example, in the optical member 20, when the luminance can be sufficiently uniformed only by the diffuse reflectors 22 and 32 and the light deflecting elements 23 and 33, or the light scattering particles are mixed into the base material 21 and the light scattering effect is given to the light passing therethrough. If it can be applied, the diffuser plate 27 may not be provided.

  A backlight unit and a display device employing the optical member described in the embodiment were manufactured, and an evaluation test of physical properties thereof was performed.

<Details of backlight device>
Size: 26 inches, light source: CCFL lamp, lamp interval: 16 mm, number of lamps: 16, lamp diameter 2.5 mm, distance between lamp and diffusion plate: 10 mm.

  The optical member was formed by integrally forming the light deflection element and the base of the diffuse reflector by extruding PC resin. For the diffuse reflector, a white transfer sheet containing titanium oxide (reflectance: 70%) was pressed immediately after extrusion molding, and the white reflection layer was transferred to the base using heat during molding. The light deflection element has a lenticular lens shape with a pitch of 150 μm and a height of 90 μm. The diffuse reflector was trapezoidal with a bottom width of 3.5 mm and a top width of 2.8 mm. Table 1 shows the results of evaluating the visibility of luminance unevenness and the transferability of the white reflective layer when the height difference (ΔH) between the light deflection element and the diffuse reflector is changed in the range of 5 μm to 200 μm. It represents.

ΔH of the optical member was in the range of 10 μm to 150 μm, and good results were obtained in both luminance unevenness and transferability of the reflective layer. When ΔH is smaller than 10 μm, when the reflective layer is transferred, ink adheres to the top of the light deflection element, and on the contrary, the visibility is deteriorated. When ΔH is larger than 150 μm, the oblique light entering from the side surface of the diffuse reflector increases, and when viewed from the diagonal, a bright spot is generated linearly at the position of the diffuse reflector, which is not suitable.
Therefore, it has been found that the above inconvenience can be solved by setting ΔH in the range of 10 μm to 150 μm.

It is typical sectional drawing which shows schematic structure of the display apparatus by 1st Embodiment. It is the elements on larger scale of an optical member. It is the figure which looked at the diffuse reflector of the optical member and the light deflection element from the back side. It is a figure explaining the optical path of the light which injects into a diffuser plate. It is a figure explaining the optical path of the light which injects into an optical member. It is a figure explaining the optical path of light in case a light deflection element is contacting the diffuser plate. (A) is the sectional side view of the base material of the optical member of a modification, a diffused reflector, and an optical deflection element, (b) is the figure which looked at the diffused reflector and the optical deflection element from the back side. (A) is the sectional side view of the base material of the optical member of a modification, a diffused reflector, and an optical deflection element, (b) is the figure which looked at the diffused reflector and the optical deflection element from the back side. It is typical sectional drawing which shows schematic structure of the display apparatus by 2nd Embodiment. It is the figure which looked at the diffuse reflector of the optical member and the light deflection element from the back side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Light source part 11 Linear light source 12 Lamp house 13 Point light source 20 Optical member 21 Base material 21a Sheet surface 21b Sheet surface 22 Diffuse reflector 22a Bottom surface 22b Flat surface 22c Slope 23 Light deflection element 24 Unit lens 25 Prism 25a Bottom surface 25b Slope 25c Top 26 Cylindrical lens 27 Diffusion plate 27a Incident surface 27b Emission surface 28 Air layer 29 Micro lens 32 Diffuse reflector 32a Bottom surface 32b Flat surface 32c Slope 33 Light deflection element 34 Unit lens 35 Micro lens 50 Optical sheet 80 Backlight unit 90 Liquid crystal panel 100 Display device 200 Display device

Claims (13)

An optical member that converts light from a plurality of light sources arranged opposite to each other along one sheet surface of a sheet-like base material that transmits light and emits the light from the other sheet surface in the front direction. And
A convex shape protruding toward the light source is formed at a position facing the plurality of light sources on the one sheet surface, and part of light emitted from the light source in the front direction is transmitted and other light is transmitted. Diffuse reflectors that diffusely reflect are arranged,
A plurality of convex unit lenses are juxtaposed over the entire area between the diffuse reflectors on the one sheet surface, and light emitted from the light source with an inclination from the front direction is emitted in the front direction. An optical member provided with a light deflecting element for condensing light. The diffuse reflector protrudes more toward the light source than the unit lens, and its top is a flat surface.
The optical member according to claim 1, wherein a diffusion plate having a flat plate shape is provided in parallel with the base material and in contact with each of the flat surfaces.   The optical member according to claim 1 or 2, wherein a difference ΔH in height from the one sheet surface of the diffuse reflector and the unit lens is set in a range of 10 nm to 150 nm. The diffuse reflectors extend in a one-dimensional direction on the one sheet surface so as to be parallel to each other,
4. The optical member according to claim 1, wherein the unit lens extends in a one-dimensional direction in parallel with the diffuse reflector. 5.   The optical member according to claim 4, wherein the unit lens is either a prism or a lenticular lens. The diffuse reflectors extend in a one-dimensional direction on the one sheet surface so as to be parallel to each other,
4. The optical member according to claim 1, wherein a plurality of the unit lenses are arranged in a two-dimensional direction on the one sheet surface. 5. The diffuse reflectors are arranged in a two-dimensional direction at intervals from each other on the one sheet surface,
4. The optical member according to claim 1, wherein a plurality of the unit lenses are arranged in a two-dimensional direction on the one sheet surface. 5.   8. The optical member according to claim 6, wherein the unit lens is any one of a micro lens, a triangular pyramid lens, and a quadrangular pyramid lens.   The optical member according to claim 1, wherein light scattering particles are dispersed and mixed in the base material.   The diffuse reflector is configured by providing a light reflecting layer on a surface of a light-transmitting base formed in a convex shape from the one sheet surface toward the light source. The optical member according to any one of 1 to 9. The optical member according to any one of claims 1 to 10,
A backlight unit comprising: a light source unit in which the light sources are respectively disposed at positions facing the diffuse reflector.   An optical sheet that controls and emits at least one of an emission direction, an emission range, and a luminance distribution of light emitted from the other sheet surface is provided on the other sheet surface side of the optical member. The backlight unit according to claim 11. A backlight unit according to claim 12;
A display device comprising: an image display element that displays an image by light irradiation from the backlight unit.

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