JP4410840B2 - Optical adjusting member, and illumination device and liquid crystal display device including the same - Google Patents

Description

  The present invention relates to an optical adjustment member that controls the traveling direction of incident light, and an illumination device and a liquid crystal display device including the same.

  Conventionally, various illumination devices such as a backlight unit such as a liquid crystal display have a mechanism for adjusting the spread and brightness of light rays from a light source. In many illuminating devices, an optical adjusting member such as a sheet for controlling the directivity of light is installed in the light path or the exit of the light source housing. This optical adjusting member has light transmittance and has a function of aligning incident light in a predetermined direction or a function of diffusing incident light.

  A typical example of an optical adjustment member having a function of aligning incident light in a predetermined direction, that is, a function of controlling light directivity, includes a prism sheet (see, for example, Patent Document 1). The prism sheet has an optical structure (hereinafter, also referred to as a prism-like structure) having a triangular cross section extending in a predetermined direction and perpendicular to the extending direction, or a semicircular (semi-elliptical) cross section. A structure in which a plurality of optical structures (hereinafter also referred to as lens-like structures) are continuously arranged on a sheet-like base material is generally used. And the advancing direction of a light beam is controlled by the prism effect or lens effect by these optical structures formed on the base material.

  Also, in a backlight unit for a liquid crystal display device, conventionally, for example, two prism sheets each having a plurality of the prism-like structures described above are provided on a substrate, and the extending directions of the prism-like structures of each prism sheet are mutually connected. It arrange | positions so that it may orthogonally cross (for example, refer patent document 1). A general configuration of such a backlight unit for a liquid crystal display device is shown in FIG. The general structure of the prism sheet is shown in FIG. As shown in FIG. 5, a backlight unit 501 for a liquid crystal display device mainly includes a light source 503, a light guide plate 504 that converts light 510 emitted from the light source 503 into a surface light source, and a lower portion of the light guide plate 504 (liquid crystal The reflection sheet 505 is disposed on the side opposite to the display panel 502, and a large number of functional optical sheet groups 506 to 508 are disposed on the light guide plate 504 (on the liquid crystal display panel 502 side). The functional optical sheet group mainly includes a lower diffusion sheet 506, a prism sheet group 507, an upper diffusion sheet 508, and the like.

  The backlight unit as shown in FIG. 5 is a so-called edge light (side light) type illumination device in which a light source 503 is arranged on the side of a light guide plate 504, and light 510 emitted from the light source 503 is emitted from the light guide plate. The incident light enters the side portion 504 and exits from the surface 504 a of the light guide plate 504. At this time, the directivity of the emitted light 511 from the light guide plate 504 is uniform to some extent, and the direction is inclined at a predetermined angle with respect to the normal direction of the output surface 504a of the light guide plate 504. And the brightness | luminance of the emitted light 511 becomes the maximum in this inclination direction. Hereinafter, in this specification, a light ray component that travels in a direction in which the luminance of the light ray becomes maximum is referred to as a “luminance peak light ray”. In FIG. 5, the optical members are illustrated apart from each other for easy understanding of the configuration of the liquid crystal display device 500, but actually, the optical members are stacked in contact with each other.

  The prism sheet group 507 includes two prism sheets 507a and 507b, and each prism sheet extends in a predetermined direction on the sheet-like base material 507c and extends in the extending direction as shown in FIG. It has a structure in which a plurality of prismatic structures 507d whose cross sections perpendicular to each other are triangular are arranged in parallel. In the backlight unit 501, the prismatic structures 507d of the prism sheets 507a and 507b are arranged so that the extending directions thereof are orthogonal to each other.

  Patent Document 2 discloses an antiglare sheet having a transparent base sheet and a plurality of triangular prisms arranged on one side thereof. Here, the triangular prisms are arranged so that the extending directions of the ridge lines are parallel to each other. The cross-sectional shape of each triangular prism in the plane orthogonal to the extending direction of the ridgeline is an asymmetric triangle. In addition, a plurality of projections and depressions (wires) parallel to the ridge line are formed on the slope of each triangular prism that has a larger angle with the base material sheet. In this way, by providing a plurality of filaments on one inclined surface of the triangular prism, in the irradiation light from the back surface (base sheet side), light that becomes a multiple image or external light due to internal reflection of the prism Light that becomes glare by reflected light of incident light is diffused out of the field of view, and a part of the diffused and transmitted light is reused as back irradiation light. Thereby, compared with the conventional anti-glare sheet, a bright and high-contrast anti-glare sheet is realized.

Japanese National Patent Publication No. 10-506500 JP-A-8-54503

  As described above, in the conventional backlight unit (backlight unit) for the liquid crystal display device, the light emitted from the light guide plate is collected and effectively irradiated to the liquid crystal display plate as shown in FIG. A prism sheet (optical adjustment member) having a plurality of prism-shaped (triangular prism-shaped) optical structures has been used. Although this conventional prism sheet has excellent light collecting performance, there is a problem that the color of light emitted from the prism sheet is separated by one prism sheet. As a result, when the object is illuminated with the illumination device using the prism sheet, the shadow edge of the object is colored and blurred, or when the prism sheet is used in a backlight unit of a liquid crystal display device, There was a problem that the colors looked different when viewed from a certain angle and when viewed from the front.

  The above-described problem of color separation will be described more specifically with reference to FIG. FIG. 8 is an enlarged cross-sectional view of the prism-like structure 507d of the prism sheet 507a shown in FIG. 6, and the light by the prism-like structure 507d when the light 512 is incident on the prism sheet 507a at a predetermined incident angle. It is the figure which showed the mode of refraction. In FIG. 8, in order to make the above-described color separation problem easier to understand, when a conventional prism sheet is directly arranged on the light exit surface of the light guide plate, that is, an edge light type having a configuration as shown in FIG. The state of light refraction in the backlight unit is shown. A light ray 512 in FIG. 8 indicates a light ray component that travels in a direction in which the luminance of the light ray reaches the maximum, that is, a luminance peak light ray, among the light rays incident on the prism sheet 507a.

  As shown in FIG. 8, the luminance peak light beam 512 incident on the prismatic structure 507d is refracted by the light traveling direction surface 507e of the prismatic structure 507d and is emitted in the thickness direction of the prism sheet 507a. . At this time, since the refractive index of the forming material of the prismatic structure 507d (prism sheet 507a) varies depending on the wavelength of light, the amount of refraction at the surface 507e of the prismatic structure 507d according to the wavelength component included in the luminance peak light beam 512. Is different. As a result, as shown in FIG. 8, the refraction direction of the refracted light on the surface 507e of the prismatic structure 507d changes according to the wavelength, and color separation occurs in a predetermined pattern in the emitted light 513 from the prism sheet 507a. In FIG. 8, only two wavelength components are separated in order to simplify the description.

  In addition to the above-described problem of color separation, there is a problem that luminance is insufficient when only one prism sheet is used. In a backlight unit used in a conventional liquid crystal display device or the like, particularly an edge light type backlight unit, a prism sheet is usually used as shown in FIG. Two sheets are used in layers.

  However, as described above, in the illumination device and the liquid crystal display device configured as shown in FIG. 5, in order to solve the above problems, a large number of optical sheet groups (in the example of FIG. 5, two prism sheets, a diffusion sheet). 2), and there was a limit to reducing the thickness and cost of the lighting device and the liquid crystal display device.

  The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to solve the above-described problems of color separation and insufficient luminance with a single optical adjusting member, and to provide an illumination device and a liquid crystal display device. It is an object to provide an optical adjustment member that can be made thinner and lower in cost.

According to the first aspect of the present invention, there is provided an optical adjustment member in which light is incident from a predetermined direction,
A base material having a light incident surface on which the light is incident and having light transmittance;
A plurality of linear bodies having light transmissivity provided on a surface of the substrate opposite to the light incident surface;
The cross section perpendicular to the extending direction of the linear body has a triangular first cross section defined by the first to third sides, an area smaller than the first cross section, and the fourth to sixth sides. A substantially triangular second cross section defined, wherein the first side of the first cross section is in contact with the surface opposite to the light incident surface of the substrate, and the second cross section Is provided on the second side of the first cross section, and the fourth side of the second cross section is in contact with the second side of the first cross section,
The angle formed by the first side and the second side of the first cross section is smaller than the angle formed by the first side and the third side,
A color separation pattern of the light refracted on the surface of the linear body including the second side of the second cross section, and a color separation pattern of the light refracted on the surface of the linear body including the sixth side of the second cross section. However, an optical adjustment member is provided, which has a reverse pattern with respect to the traveling direction of the light and cancels color separation from each other.

  When the present inventors have made extensive studies on the optical adjustment member that controls the traveling direction of the incident light, the use of the optical adjustment member having the above-described structure can suppress the color separation of the emitted light from the optical adjustment member. I understood. This includes the color separation pattern of the light refracted on the surface of the linear body including the fifth side of the second cross-sectional portion and the sixth side of the second cross-sectional portion by making the optical adjustment member the structure described above. The color separation pattern of the light refracted on the surface of the linear body is opposite to the traveling direction of the light incident on the optical adjustment member, and the surface of the linear body including the fifth side of the second cross section This is to cancel the color separation between the light refracted in step 1 and the light refracted on the surface of the linear body including the sixth side of the second cross section (the principle of suppressing color separation will be described in detail later). .

  Furthermore, in the optical adjustment member of the present invention, by using the above-described structure, it is possible to directly change the traveling direction of the light beam emitted from the light guide plate with a certain degree of directivity to the thickness direction of the optical adjustment member. Thus, unlike the prior art, it is not necessary to provide a lower diffusion sheet between the prism sheet group and the light guide plate. That is, in the optical adjustment member of the present invention, unlike the conventional case, it is not necessary to once convert light having a certain degree of directivity emitted from the light guide plate using the lower diffusion sheet into broad light. Therefore, the utilization efficiency of the light emitted from the light guide plate can be improved and the luminance characteristics can be improved. That is, in the optical adjustment member of the present invention, the above-described problems of color separation of emitted light and insufficient luminance can be solved with one optical adjustment member.

  In particular, when the optical adjustment member of the present invention is applied to an edge light type illumination device or the like, color separation of the emitted light can be suppressed by one optical adjustment member. There is no need to use two prism sheets to suppress color separation. Further, as described above, when the optical adjustment member of the present invention is used, it is not necessary to provide a lower diffusion sheet between the prism sheet group and the light guide plate as in the conventional case. Therefore, when the optical adjustment member of the present invention is applied to an edge light type illumination device or the like, the number of optical members can be reduced, and the device can be reduced in thickness and cost.

  In the optical adjustment member related to the present invention, it is preferable that a plurality of second cross-sectional portions are provided on the second side of the first cross-sectional portion.

  In the optical adjustment member related to the present invention, it is preferable that all of the plurality of second cross-sectional portions have the same shape and size. In the optical adjustment member of the present invention, it is preferable that the shapes of the plurality of second cross-sectional portions are similar to each other. Moreover, in the optical adjustment member of this invention, it is preferable that the vertex angle which opposes the 4th side of a said some 2nd cross-section part is the same angle mutually.

  In the optical adjustment member related to the present invention, of the fifth and sixth sides of the second cross section, the side closer to the apex angle facing the first side of the first cross section is shorter than the other side. Is preferred. With such a configuration, for example, as shown in FIGS. 1 and 2, two apexes (for example, the corner 12 e in FIG. 1) that face the fourth side 12 b of the second cross-sectional portion 12 a are defined. Among the surfaces, a condensing surface 12f of the linear body 13 that refracts the luminance peak light ray 52 in the thickness direction of the optical adjustment member 1 (a surface including the side 12c far from the apex angle 11e of the first cross-sectional portion 11a). Can be wider. Therefore, in this case, since the light incident on the condensing surface of the linear body is increased (because the light rays to be collected are increased), the utilization efficiency of the incident light is further improved, and the luminance characteristics are further improved. Can do.

  In the optical adjustment member related to the present invention, when the luminance peak light beam traveling in the direction in which the luminance is maximized in the luminance characteristic of the light beam incident on the optical adjustment member is refracted by the optical adjustment member, the second cross-sectional portion The direction of travel of the luminance peak light beam after being refracted on the surface of the linear body including the fifth side and the luminance peak light beam after being refracted on the surface of the linear body including the sixth side of the second cross section. The fifth side and the sixth side of the second cross-sectional portion are inclined with respect to the fourth side so that the traveling direction is opposite to the traveling direction of the luminance peak light beam before refraction. preferable.

  In the optical adjustment member related to the present invention, the inclination direction of the third side of the first cross section with respect to the first side is substantially parallel to the direction in which the luminance is maximum in the luminance characteristic of the light beam incident on the optical adjustment member. Preferably there is. More preferably, the angle between the third side and the first side of the first cross section (for example, β1 in FIG. 2) is a luminance peak ray (for example, the ray in FIG. 2) incident on the optical adjustment member. 52) is preferably equal to or larger than an angle of the substrate surface (for example, 90 degrees -θ in FIG. 2). With such a configuration, the reflection and refraction of incident light on the surface of the linear body including the third side of the first cross section (for example, the surface 13c in FIG. 1) becomes very small. Efficiency is further improved.

  In the optical adjustment member related to the present invention, it is preferable that the plurality of linear bodies are periodically arranged in a direction orthogonal to the extending direction.

According to the second aspect of the present invention, there is provided an optical adjustment member in which light is incident from a predetermined direction,
A base material having a light incident surface on which the light is incident and having light transmittance;
A plurality of linear bodies, provided on a surface of the substrate opposite to the light incident surface, having light transmittance, and each having a condensing surface and a correction surface A linear body,
The cross section perpendicular to the extending direction of the linear body is substantially triangular, and one of the three sides defining the cross section is parallel to the surface opposite to the light incident surface of the substrate. One of the other two sides is stepped, and the stepped side is a line of intersection of the cross section, the light collection surface and the correction surface, and the cross section The angle formed between the side parallel to the base material and the stepped side is smaller than the angle formed between the side parallel to the base material and the remaining side,
The light color separation pattern refracted on the light collecting surface of the linear body and the light color separation pattern refracted on the correction surface of the linear body are opposite to each other in the light traveling direction. An optical adjustment member is provided which is a pattern and cancels color separation from each other. In this application, the term “light condensing surface” is a light emitting surface of a linear body, and refracts light incident from the side of the base material in the thickness direction of the optical adjustment member (thickness direction of the base material). The term “correction surface” refers to a light emitting surface of a linear body that refracts light incident from the substrate side in the surface direction of the optical adjustment member (surface direction of the substrate). Say.

  According to a third aspect of the present invention, there is provided a lighting device, the light source, the optical adjustment member according to the first or second aspect of the present invention, and the light emitted from the light source is guided to the optical adjustment member. An illuminating device including a light guide plate is provided.

  According to a fourth aspect of the present invention, there is provided a liquid crystal display device comprising a light source, an optical adjustment member according to the first or second aspect of the present invention, and light emitted from the light source as the optical adjustment member. There is provided a liquid crystal display device comprising a light guide plate for guiding and a liquid crystal display element arranged on the side of the optical adjustment member opposite to the light guide plate side.

  Since the illumination device and the liquid crystal display device according to the present invention include the optical adjustment member according to the present invention, as described above, the number of optical members to be configured can be reduced, and the device can be reduced in thickness and cost. be able to. Furthermore, since the illumination device and the liquid crystal display device of the present invention include the optical adjustment member of the present invention, color separation can be suppressed and use efficiency of light emitted from the light guide plate is improved. Luminance characteristics can also be improved.

  In the illumination device and the liquid crystal display device of the present invention, it is preferable that the optical adjustment member is disposed in contact with the light guide plate.

  The liquid crystal display device may further include a reflecting member disposed on the opposite side of the light guide plate from the optical adjustment member side.

  In the optical adjustment member of the present invention, a single optical adjustment member is provided by providing a plurality of linear bodies on the substrate whose cross section orthogonal to the extending direction is substantially triangular and one side of the cross section is stepped. Thus, color separation of emitted light can be suppressed. Further, in the optical adjustment member of the present invention, the traveling direction of the light having a certain degree of directivity emitted from the light guide plate can be directly changed to the thickness direction of the optical adjustment member, so that the light emitted from the light guide plate It is also possible to improve the use efficiency and the luminance characteristics. That is, according to the optical adjustment member of the present invention, color separation of emitted light can be suppressed and luminance characteristics can be improved by one optical adjustment member.

  According to the illumination device and the liquid crystal display device of the present invention, since the optical adjustment member of the present invention is provided, the illumination device and the liquid crystal display device can be made thinner and lower while solving the problems of light color separation and insufficient luminance. Cost can be reduced.

1 is a schematic configuration diagram of an optical adjustment sheet of Example 1. FIG. FIG. 2 is an enlarged cross-sectional view of the linear optical structure according to the first embodiment. FIG. 3 is a schematic configuration diagram of the liquid crystal display device according to the first embodiment. FIG. 4 is an enlarged cross-sectional view of the linear optical structure according to the second embodiment. FIG. 5 is a schematic configuration diagram of the liquid crystal display device of Comparative Example 1. FIG. 6 is a schematic configuration diagram of a prism sheet of Comparative Example 1. FIG. 7 is a schematic configuration diagram of a liquid crystal display device of Comparative Example 2. FIG. 8 is a diagram showing a state of color separation of emitted light.

  Hereinafter, examples of the optical adjustment member, the illumination device, and the liquid crystal display device of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

[Configuration of optical adjustment sheet]
The schematic block diagram of the optical adjustment sheet (optical adjustment member) of Example 1 is shown in FIG. As shown in FIG. 1, the optical adjustment sheet 1 of this example includes a sheet-like light transmissive (transparent) base material 10 and a plurality of linear optical structures 13 (linear bodies) formed on the base material 10. ).

  In this example, a polyethylene terephthalate (PET) sheet having a thickness of 50 μm was used as the substrate 10. In addition, the thickness of the base material 10 is preferably in the range of 10 to 500 μm in consideration of ease of processing of the optical adjustment sheet, handling properties, and the like. Further, as a material for forming the base material 10, any light transmissive material such as an inorganic transparent substance such as polyethylene naphthalate, polystyrene, polycarbonate (PC), polyolefin, polypropylene, cellulose acetate, glass, or the like is used other than PET. Can do. The shape of the base material 10 is typically a sheet shape as in this example, but a thicker plate shape or an arbitrary shape base material may be used. Furthermore, the surface of the base material 10 is not limited to a flat surface and may be a three-dimensional surface.

  As shown in FIG. 1, the linear optical structure 13 has a substantially triangular cross section orthogonal to the extending direction, and one surface 13a (hereinafter also referred to as a bottom surface) along the extending direction is a base material. 10 in parallel with the surface. That is, the linear optical structure 13 is provided on the base material 10 so that the bottom surface 13 a faces the surface of the base material 10.

  Further, in this example, as shown in FIG. 1, the plurality of linear optical structures 13 are all the same in shape and size, and the plurality of linear optical structures 13 are periodically arranged in a direction orthogonal to the extending direction. And the bottom corners of the adjacent linear optical structures 13 are in contact with each other. In addition, it is preferable that the arrangement | positioning space | interval (pitch) of the some linear optical structure 13 is about 7-100 micrometers. When the arrangement interval of the plurality of linear optical structures 13 is smaller than 7 μm, high-precision mold processing is required for the mold used to form the linear optical structures 13, and the cost increases. Moreover, when the arrangement | positioning space | interval of the some linear optical structure 13 becomes larger than 100 micrometers, especially when a sheet-like base material is used, the following problems will arise. When the arrangement interval of the plurality of linear optical structures 13 is larger than 100 μm, the size of the linear optical structures 13 is also relatively increased, and the volume of the resin forming the linear optical structures 13 is increased. As a result, the amount of cure shrinkage of the resin when the linear optical structure 13 is formed by curing the resin also increases. In this case, the so-called “biting” of the resin with respect to the mold becomes strong, and the resin becomes difficult to peel from the mold. In particular, when the linear optical structure 13 is formed on a sheet-like substrate using a roll-shaped mold, the linear optical structure 13 is destroyed at the time of peeling, or the linear optical structure 13 is The problem of remaining on the mold surface arises. Moreover, when the arrangement | positioning space | interval of the some linear optical structure 13 becomes larger than 100 micrometers, since the height of the linear optical structure 13 will also become high, it will become a thick optical adjustment member.

  In this example, the linear optical structure 13 is formed of an aromatic acrylate ultraviolet curable resin (refractive index of 1.60). In addition, as a forming material of the linear optical structure 13, an arbitrary resin material having a refractive index of 1.3 to 1.9 can be used. Further, as in this example, when the linear optical structure 13 is formed of a material different from the forming material of the base material 10, the forming material includes an acrylic resin, a urethane resin, a styrene resin, an epoxy resin, a silicone-based material. A transparent plastic resin such as a resin may be used. The linear optical structure 13 may be formed of the same material as the base material 10.

  Further, as shown in FIG. 1, the linear optical structure 13 includes a first linear prism portion 11 formed on the base material 10 and extending in the same direction as the extending direction of the linear optical structure 13. A plurality of second linear prism portions 12 formed on one surface defining the apex angle of the first linear prism portion 11 and extending in the same direction as the extending direction of the linear optical structure 13; Consists of In this example, as will be described later, the first linear prism portion 11 and the second linear prism portion 12 are integrally formed. That is, in this example, the surface 13b of the linear optical structure 13 on which the plurality of second linear prism portions 12 are formed has a step shape (hereinafter also referred to as a step surface). In this example, as shown in FIG. 1, three second linear prism portions 12 are formed on one surface that defines the apex angle of the first linear prism portion 11, but the present invention is not limited to this. It is not limited to. The number and shape of the second linear prism portions 12 can be changed as appropriate according to the application, required optical characteristics, and the like. Further, the second linear prism portion 12 may be provided on both of the two surfaces that define the apex angle of the first linear prism portion 11 depending on the application, required optical characteristics, and the like.

  An enlarged sectional view of the linear optical structure 13 is shown in FIG. Note that the incident light beam 52 shown in FIG. 2 travels in the direction in which the luminance is maximized in the luminance characteristics of the light beam incident on the optical adjustment sheet 1 (traveling through the optical adjustment sheet 1), that is, the luminance. Peak light is shown. As shown in FIG. 2, the cross section perpendicular to the extending direction of the linear optical structure 13 includes a first cross section 11 a of the first linear prism section 11 and a second cross section of the second linear prism section 12. Part 12a.

  As shown in FIG. 2, the first cross-sectional portion 11a has a base 11b (first side) that is in contact with the surface of the substrate 10 and predetermined angles from both ends of the base 11b (α1 and β1 in FIG. 2). Are defined by two inclined sides 11c (second side) and 11d (third side) extending in the above. In this example, as shown in FIG. 2, of the two inclined sides 11c and 11d that define the apex angle 11e facing the base 11b of the first cross section 11a, the inclined side 11c (in contact with the second cross section 12a) The length of the second side) is longer than the other inclined side 11d (third side). Therefore, the angle α1 between the base 11b and the inclined side 11c of the first cross section 11a (first base angle) is the angle between the base 11b and the inclined side 11d (second base angle). It becomes smaller than β1. That is, in this example, the shape of the first cross section 11a is an asymmetric triangle (not an isosceles triangle).

  In this example, as shown in FIG. 2, the inclination angle of the inclined side 11 d of the first cross-sectional portion 11 a with respect to the normal direction of the surface of the base material 10 is expressed by the luminance peak light ray 52 with respect to the normal direction of the surface of the base material 10. It was made to be substantially the same as the inclination angle (θ in FIG. 2) in the traveling direction. That is, the inclination direction of the surface of the linear optical structure 13 including (corresponding to) the inclined side 11d in FIG. 2 (the surface 13c in FIG. 1; hereinafter, this surface is also referred to as a flat surface) is the luminance peak ray 52. It was made to be substantially parallel to the traveling direction. In this example, as will be described later, the inclination angle (β1 in FIG. 2) of the flat surface 13c of the linear optical structure 13 with respect to the substrate surface is determined based on the luminance peak ray 52 in the linear optical structure 13. It was made to be slightly larger than the inclination angle (90 ° −θ) with respect to the material surface.

  The specific dimensions of the first cross section 11a in this example are such that the length of the base 11b of the first cross section 11a is 35 μm, the angle α1 of the first base angle of the first cross section 11a is 39.14 degrees, The angle β1 of the second base angle was 57.71 degrees.

  As shown in FIG. 2, the second cross-sectional portion 12a has a base 12b (fourth side) in contact with the inclined side 11c (second side) of the first cross-sectional portion 11a and a predetermined angle from both ends of the base 12b. It is defined by two inclined sides 12c and 12d extending at (α2 and β2 in FIG. 2). In this example, as shown in FIG. 2, of the two inclined sides 12c and 12d of the second cross section 12a, the inclined side 12d located on the side close to the apex angle 11e facing the base 11b of the first cross section 11a. Was made shorter than the other inclined side 12c. Therefore, the angle α2 between the base 12b and the inclined side 12c of the second cross section 12a (first base angle) is the angle between the base 12b and the inclined side 12d (second base angle). It becomes smaller than β2. That is, in this example, the shape of the second cross section 12a is an asymmetric triangle (not an isosceles triangle).

  The surface 12f of the second linear prism portion 12 including the inclined side 12c (fifth side or sixth side) of the second cross-sectional portion 12a mainly optically adjusts the traveling direction of the incident light, as will be described later. It is a surface that is refracted in the thickness direction of the sheet 1, that is, a surface that has a function of collecting incident light. Therefore, hereinafter, the surface 12f including the inclined side 12c of the second cross-sectional portion 12a is referred to as a condensing surface. On the other hand, the surface 12r of the second linear prism portion 12 including the other inclined side 12d (fifth side or sixth side) of the second cross section 12a is mainly formed from the optical adjustment sheet 1 as described later. In the following, it will be referred to as a correction surface.

  Like the optical adjustment sheet 1 of this example, the length of the inclined side 12c of the second cross-sectional portion 12a located on the side far from the apex angle 11e of the first cross-sectional portion 11a is made longer than the other inclined side 12d. Thereby, the condensing surface 12f of the 2nd linear prism part 12 (linear optical structure 13) can be made wider, and the utilization efficiency of incident light can be improved.

  In this example, as shown in FIG. 2, the refraction direction of the light beam 53 when the luminance peak light beam 52 incident on the optical adjustment sheet 1 is refracted by the light collecting surface 12 f of the second linear prism portion 12, and The refraction direction of the light ray 54 when refracted by the correction surface 12r of the second linear prism part 12 is opposite to the traveling direction of the luminance peak light ray 52 before refraction. The angles α2 and β2 of the first and second base angles were set. In this example, the refraction direction of the predetermined wavelength component of the light beam 53 (for example, the wavelength A component 53A in FIG. 2) when refracted by the condensing surface 12f of the second linear prism portion 12 and the luminance before refraction. A predetermined wavelength component (for example, in FIG. 2) of the light beam 54 when the angle (angle γ in FIG. 2) with the traveling direction of the peak light beam 52 is refracted by the correction surface 12r of the second linear prism portion 12. The angle α2 of the first and second base angles of the second cross section 12a so that the angle between the refraction direction of the wavelength A component 54A) and the traveling direction of the luminance peak ray 52 before refraction is substantially the same. And β2. With such a configuration, the color separation of the emitted light from the optical adjustment sheet 1 can be further suppressed.

  If the color separation of the emitted light from the optical adjustment sheet 1 is within a range that can be sufficiently suppressed, the predetermined wavelength component of the light beam 53 refracted by the light condensing surface 12f of the second linear prism portion 12 will be described. The angle between the refraction direction and the traveling direction of the luminance peak light ray 52 before refraction, the refraction direction of the predetermined wavelength component of the light ray 54 when refracted by the correction surface 12r of the second linear prism portion 12, and The angle between the luminance peak light beam 52 and the traveling direction may be different.

  The specific dimensions of the second cross section 12a in this example are such that the length of the base 12b of the second cross section 12a is about 10.44 μm, and the angle α2 of the first base angle of the second cross section 12a is 30 degrees. The angle β2 of the second base angle of the second cross section 12a was set to 70 degrees.

  In this example, the shapes and dimensions of the three second linear prism portions 12 are all the same, and the three second linear prism portions 12 are periodically arranged in a direction perpendicular to the extending direction, and adjacent to each other. The bottom corners of the matching second linear prism portions 12 are arranged so as to contact each other. That is, in this example, the condensing surfaces 12f and the correction surfaces 12r of the plurality of second linear prism portions 12 constituting the staircase surface 13b of the linear optical structure 13 are arranged in parallel with each other at equal intervals. The structure was as follows.

[Method for producing optical adjustment sheet]
The manufacturing method of the optical adjustment sheet 1 of this example is as follows. A roll-shaped mold is prepared in which an uneven pattern corresponding to the shape of an optical structure composed of a plurality of linear optical structures 13 as shown in FIG. 1 is formed on the surface by cutting. Next, an ultraviolet curable resin was filled between the prepared substrate 10 and the mold surface, and the filled ultraviolet curable resin was cured by irradiation with ultraviolet rays having a wavelength of 340 to 420 nm. Next, the substrate 10 was peeled from the mold. In this example, an optical adjustment sheet 1 in which a plurality of linear optical structures 13 made of an ultraviolet curable resin was formed on the substrate 10 in this way was obtained.

  In addition, the manufacturing method of the optical adjustment sheet | seat of this invention is not limited to the said method, A well-known arbitrary method can be used. For example, a base material is made of a thermoplastic resin, and a mold having an uneven pattern corresponding to the shape of an optical structure composed of a plurality of linear optical structures is formed on the surface by heating and pressing the base material. The optical structure may be directly formed on the base body by a thermal transfer method for transferring the concave / convex pattern of the mold. Further, an optical structure composed of a plurality of linear optical structures may be formed on the substrate by a known extrusion molding method, press molding method, or injection molding method in which a molten resin is injected into a mold. In this case, the base material and the linear optical structure are formed of the same material.

[Liquid crystal display device and lighting device]
A schematic configuration of a liquid crystal display device using the optical adjustment sheet 1 of this example is shown in FIG. In FIG. 3, the optical members are illustrated apart from each other for easy understanding of the configuration of the liquid crystal display device. However, in the actual device, the optical members are stacked in contact with each other. As shown in FIG. 3, the liquid crystal display device 100 of this example includes a liquid crystal display panel 7 (liquid crystal display element) and a backlight unit 6 (illumination device).

  As the liquid crystal display panel 7, a liquid crystal display panel used in a conventional liquid crystal display device was used. Specifically, although not shown here, the structure of the liquid crystal display panel 7 includes a polarizing plate, a glass substrate, a transparent conductive film forming a pixel electrode, an alignment film, a liquid crystal layer, an alignment film, and a transparent conductive film forming a counter electrode. A film, a color filter, a glass substrate, and a polarizing plate were laminated in this order.

  As shown in FIG. 3, the backlight unit 6 mainly includes a light source (LED: light emitting diode) 2, a light guide plate 3 that emits light 50 incident on a side portion thereof from an upper surface 3 a (an emission surface), and a light guide plate 3. The reflective sheet 4 (reflective member) disposed at the lower part of the light plate 3 (on the side opposite to the liquid crystal display panel 7), and the optical adjustment sheet 1 of this example disposed at the upper part of the light guide plate 3 (on the liquid crystal display panel 7 side). And a diffusion sheet 5 disposed on the optical adjustment sheet 1. In this example, as shown in FIG. 3, the optical adjustment sheet 1 of this example is mounted on the liquid crystal display device so that the stepped surface 13b of the linear optical structure 13 is the main light receiving surface for incident light. . The backlight unit 6 in this example is an edge light type illumination device, and the light source 2 is provided on the side of the light guide plate 3.

  The optical members other than the optical adjustment sheet 1 were the same as the optical members of the conventional backlight unit. Specifically, the light guide plate 3 was formed of polycarbonate. In this example, the angle between the direction in which the luminance of the light 51 emitted from the emission surface 3a of the light guide plate 3 is maximized (the direction of the luminance peak light beam) and the direction relative to the normal direction of the emission surface 3a is The light guide plate 3 having an emission characteristic of 70 degrees was used. Therefore, when the outgoing light 51 from the light guide plate 3 is incident on the optical adjustment sheet 1, the light 51 is refracted on the lower surface of the base 10 of the optical adjustment sheet 1, and the base of the light 51 in the traveling direction of the luminance peak ray. The inclination angle θ with respect to the normal direction of the surface of the material 10 (the thickness direction of the optical adjustment sheet 1) is about 36 degrees. That is, the inclination angle θ in the traveling direction of the luminance peak light beam 52 incident on the optical adjustment sheet 1 is the inclination direction of the flat surface 13 c of the linear optical structure 13 of the optical adjustment sheet 1 and the normal direction of the surface of the substrate 10. It was adjusted to be slightly larger than the angle between (90 degrees-α1 = 32.29 degrees).

  As the reflection sheet 4, a sheet in which silver was deposited on the surface of a PET film was used. The diffusion sheet 5 used was a PET film bead-coated with a thickness of 70 μm and a haze of 30%.

[Suppression principle of color separation]
Next, in the optical adjustment sheet 1 of this example, the principle that color separation of light emitted from the optical adjustment sheet 1 is suppressed will be described with reference to FIGS.

  When the outgoing light 51 from the light guide plate 3 is incident on the optical adjustment sheet 1 of this example, the incident light is mainly the staircase surface 13b of the linear optical structure 13, that is, the second linear prism portion 12. Refracted at. In addition, since the inclination direction of the flat surface 13c of the linear optical structure 13 is substantially parallel to the traveling direction of the luminance peak light ray 52 of the light ray incident on the optical adjustment sheet 1 as described above, the flat surface 13c. The influence of refraction of incident light at is relatively small.

  The luminance peak light ray 52 incident on the staircase surface 13b of the linear optical structure 13 has two surfaces defining each convex surface (each step surface) of the staircase surface 13b, that is, the second linear prism portion 12. The light is refracted by the condensing surface 12f and the correction surface 12r. At this time, as shown in FIG. 2, the luminance peak light beam 52 is refracted in the thickness direction of the optical adjustment sheet 1 (the normal direction of the surface of the substrate 10) on the light condensing surface 12f of the second linear prism portion 12. (Light ray 53 in FIG. 2), the correction surface 12r is refracted in the in-plane direction of the optical adjustment sheet 1 (in-plane direction of the substrate 10) (light ray 54 in FIG. 2). That is, the traveling direction of the light beam 53 refracted by the condensing surface 12f of the second linear prism portion 12 and the traveling direction of the light beam 54 refracted by the correction surface 12r are relative to the traveling direction of the luminance peak light beam 52 before refraction. Are opposite to each other.

  Further, when the luminance peak light beam 52 is incident on the stepped surface 13b of the linear optical structure 13 and is refracted, the refractive index of the material forming the linear optical structure 13 varies depending on the wavelength of the incident light beam. The refraction angle differs depending on each wavelength component included in the peak light ray 52, and color separation of the refracted lights 53 and 54 occurs as shown in FIG. In FIG. 2, separation of two wavelength components (wavelengths A and B, wavelength A> wavelength B) is shown to simplify the description. The light rays 53A and 54A in FIG. 2 indicate the refracted light of the wavelength A component, the light rays 53B and 54B indicate the refracted light of the wavelength B component, and the refraction of the wavelength B component in FIG. In this case, the refraction is larger than the refraction (the refraction angle is large).

  When the luminance peak light beam 52 is refracted by the condensing surface 12f of the second linear prism portion 12, the wavelength B component 53B of the refracted light 53 is refracted more than the wavelength A component 53A as shown in FIG. Therefore, the traveling (refractive) direction of the wavelength B component 53B is further in the direction of the arrow A1 in FIG. 2 than the wavelength A component 53A. On the other hand, when the luminance peak ray 52 is refracted by the correction surface 12r of the second linear prism portion 12, the wavelength B component 54B of the refracted light 54 is refracted to be larger than the wavelength A component 54A, and therefore the wavelength B component 54B. In the direction of arrow A2 in FIG. 2 further from the wavelength A component 54A. That is, the separation pattern of the color (wavelength) of the light beam 53 refracted by the condensing surface 12f of the second linear prism portion 12, and the color (wavelength) of the light beam 54 refracted by the correction surface 12r of the second linear prism portion 12. As shown in FIG. 2, the separation pattern is a pattern opposite to the traveling direction of the luminance peak light beam 52. Therefore, the color separation of the light beam 53 refracted by the condensing surface 12f of the second linear prism portion 12 is canceled by the color separation of the light beam 54 refracted by the correction surface 12r of the second linear prism portion 12, and optical adjustment is performed. Color separation of light emitted from the sheet 1 and collected on the liquid crystal display surface is suppressed.

  As described above, in the optical adjustment sheet 1 of this example, since the color separation of the emitted light can be suppressed by one optical sheet as described above, the color separation of the emitted light is suppressed as in the conventional case. This eliminates the need to use two prism sheets. In addition, as described above, the optical adjustment sheet 1 of this example directly changes the traveling direction of the emitted light (tilted light) from the light guide plate having a certain degree of directivity to the thickness direction of the optical adjustment sheet 1. Therefore, it is not necessary to provide a lower diffusion sheet between the prism sheet group and the light guide plate as in the prior art. Therefore, there is no need to convert light with a certain degree of directivity emitted from the light guide plate using the lower diffusion sheet into broad light as in the prior art, so the efficiency of using the light emitted from the light guide plate is eliminated. And the luminance characteristics can be improved.

  Further, in the edge light type liquid crystal display device 100 and the backlight unit 6 provided with the optical adjustment sheet 1 of this example, as shown in FIG. 3, two prism sheets are used to suppress the color separation of the emitted light. There is no need to use, and there is no need to use a lower diffusion sheet. Therefore, in the edge light type liquid crystal display device 100 and the backlight unit 6 of this example, the number of optical members can be reduced as compared with the conventional case, and the thickness and cost of the device can be reduced.

[Optical characteristics evaluation]
The optical characteristics of the liquid crystal display device 100 and the backlight unit 6 of this example shown in FIG. 3 were evaluated. Specifically, front luminance was measured using a luminance meter. Moreover, the sensory evaluation of color was performed visually. Specifically, the color of the emitted light from the backlight unit was visually observed mainly from the front direction to examine the color uniformity of the emitted light.

  Here, for the sake of comparison, the above-described evaluation was also performed for the conventional liquid crystal display device 500 (Comparative Example 1) shown in FIG. In the liquid crystal display device 500 of Comparative Example 1 shown in FIG. 5, the cross-sectional shape perpendicular to the extending direction of the prismatic structures formed on the prism sheets 507a and 507b has a base width of 30 μm and a height of 15 μm. An isosceles triangle with an apex angle of 90 degrees. The base material 507c of each prism sheet 507a was formed of a PET film, and the prismatic structure 507d was formed of an ultraviolet curable acrylic resin. The lower diffusion sheet 506 was a PET film bead-coated, the thickness was 70 μm, and the haze was 85%. The constituent optical members other than the prism sheet group 507 and the lower diffusion sheet 506 were the same as those used in the liquid crystal display device 100 of Example 1.

  Furthermore, for the purpose of comparison, the above evaluation was also performed on the liquid crystal display device 600 (Comparative Example 2) configured as shown in FIG. 7 is replaced with the conventional prism sheet 507a shown in FIG. 6 in place of the optical adjustment sheet 1 in the liquid crystal display device 100 of Example 1 shown in FIG. Is a device using a single sheet. The configuration was the same as that of the liquid crystal display device 100 of Example 1 except that the conventional prism sheet 507a was used as the optical adjustment member.

The evaluation results are shown in Table 1 below. Table 1 also shows the number of optical sheets disposed between the light guide plate and the liquid crystal panel. The front luminance is based on the front luminance of Comparative Example 1 (100%). In addition, the evaluations of color uniformity ◎ and x in Table 1 are as follows. In Table 1 below, evaluation results of Example 2 described later are also shown.
A: The color of the emitted light 55 from the backlight unit 6 is the same white color as the emitted light 50 from the light source, and the difference between the two cannot be visually determined.
X: Level at which it can be visually confirmed that the emitted light 55 from the backlight unit 6 is colored red, yellow or the like.

  As apparent from Table 1, the liquid crystal display device of Example 1 can improve the front luminance and reduce the number of optical sheets as compared with the liquid crystal display device of Comparative Example 1 (FIG. 5). I understood. That is, it has been found that the liquid crystal display device of Example 1 can improve the optical characteristics while reducing the thickness and cost of the device. Further, as is clear from Table 1, the liquid crystal display device of Example 1 was found to be able to improve both the front luminance and the color uniformity as compared with the liquid crystal display device of Comparative Example 2 (FIG. 7).

  In the optical adjustment sheet of Example 1 described above, the case where the shapes and dimensions of the plurality of second prism structures constituting the linear optical structure are all the same has been described, but the present invention is not limited to this. The shapes of the plurality of second prism structures may be similar to each other. Also in this case, since the condensing surfaces and the correction surfaces of the plurality of second prism structures are parallel to each other, the same effect as in the first embodiment can be obtained.

  In the optical adjustment sheet of Example 1 above, in order to further improve the unevenness of the luminance of the light emitted from the optical adjustment sheet and further improve the display quality, a diffusion sheet is further disposed on the optical adjustment sheet. However, the present invention is not limited to this. For example, the present invention is applied to a case where the quality of light emitted from the optical adjustment sheet is sufficiently good (when luminance unevenness is suppressed as much as possible), or a use that does not require high-quality display performance. In some cases, a diffusion sheet may not be used.

  In the liquid crystal display device and the illuminating device used in Example 1, the example in which the reflection sheet is disposed on the side opposite to the optical adjustment sheet side of the light guide plate has been described, but the present invention is not limited to this. For example, when the surface opposite to the optical adjustment sheet side of the light guide plate has a structure (such as a concavo-convex structure) that can obtain a sufficient reflection action, the reflection sheet may not be used.

  In the optical adjustment sheet of the present invention, the number of second linear prism portions constituting the step surface of the linear optical structure, the position and area ratio of the condensing surface and the correction surface on the step surface, or collection as necessary. By adjusting the inclination angle of the light surface and the correction surface, it is possible to adjust the balance of the optical characteristics such as the luminance and chromatic dispersion of the light emitted from the optical adjustment sheet. In the optical adjustment sheet of Example 2, the number, shape, and dimensions of the second linear prism portions were changed from those of Example 1 so that the amount of light incident on the light collection surface was relatively large with respect to the correction surface. . Other than that, it was set as the structure and formation material similar to Example 1. FIG.

  An enlarged cross-sectional view of the linear optical structure of the optical adjustment sheet of Example 2 is shown in FIG. As shown in FIG. 4, the linear optical structure 24 of this example has a substantially triangular cross section orthogonal to the extending direction, and one surface (a surface including the bottom side 21 b) along the extending direction. (Hereinafter also referred to as the bottom surface) is in contact with the surface of the substrate 20 in parallel. That is, the linear optical structure 24 is provided on the base material 20 so that the bottom surface thereof faces the surface of the base material 20. The incident light beam 52 shown in FIG. 4 indicates a light beam that travels in the direction in which the luminance is maximized in the luminance characteristics of the light beam incident on the optical adjustment sheet of this example, that is, a luminance peak light beam.

  As shown in FIG. 4, the cross section orthogonal to the extending direction of the linear optical structure 24 includes a first cross section 21a and two second different shapes provided on one side of the first cross section 21a. It is comprised from the cross-sectional parts 22a and 23a. That is, in this example, two second linear prism portions having different shapes on one surface of the first linear prism portion (linear structure corresponding to the first cross-sectional portion 21a) of the linear optical structure 24. (Linear structures corresponding to the second cross-sectional portions 22a and 23a) were provided. As shown in FIG. 4, the two second cross-sectional portions 22 a and 23 a are provided so that the bottom corner portions thereof are in contact with each other.

  As shown in FIG. 4, the first cross section 21a has a base 21b (first side) in contact with the surface of the substrate 20 and predetermined angles (α1 and β1 in FIG. 4) from both ends of the base 21b. Are defined by two inclined sides 21c (second side) and 21d (third side) extending in the above. In the optical adjustment sheet of this example, the shape of the first cross-sectional portion 21a (the shape of the first linear prism portion) was the same as that of Example 1. That is, the angles α1 and β1 of the first and second base angles of the first cross section 21a are 39.14 degrees and 57.71 degrees, respectively, and the length of the base 21b of the first cross section 21a is 35 μm. .

  In this example, as shown in FIG. 4, the inclination angle of the inclined side 21d of the first cross section 21a with respect to the normal direction of the surface of the substrate 20, and the traveling direction of the luminance peak light ray 52 incident on the optical adjustment sheet The inclination angle (θ in FIG. 4) was also the same as in Example 1. That is, the inclination direction of the surface (flat surface) of the linear optical structure 24 including the inclined side 21d in FIG. 4 is made substantially parallel to the traveling direction of the luminance peak light beam 52. More specifically, the angle of inclination (β1 in FIG. 4) of the flat surface of the linear optical structure 24 with respect to the surface of the base material 20 is set to a luminance peak ray in the linear optical structure 24 as in the first embodiment. 52 was slightly larger than the inclination angle (90 degrees -θ) with respect to the surface of the substrate 20.

  As shown in FIG. 4, the second cross section 22a located on the first base angle side (α1 side in FIG. 4) of the first cross section 21a is an inclined side 21c (second side) of the first cross section 21a. And a base 22b (fourth side) in contact with the base 22b and two inclined sides 22c and 22d extending from the both ends of the base 22b at predetermined angles (α2 and β2 in FIG. 4), respectively. In this example, the shape of the second cross section 22a is similar to that of the second cross section 12a of the first embodiment, and the first base angle α2 and the second base angle β2 of the second cross section 22a are set as follows. They were 30 degrees and 70 degrees, respectively. In the optical adjustment sheet of this example, the base 22b of the second cross section 22a was about 14.92 μm, which was longer than the base 12b (about 10.44 μm) of the second cross section 12a of Example 1. That is, in the optical adjustment sheet of this example, the area of the second cross-sectional portion 22a located on the first base angle side (α1 side in FIG. 4) of the first cross-sectional portion 21a is the same as that of the second cross-sectional portion 12a of Example 1. It was larger than the area.

  Note that the surface of the linear optical structure 24 (second linear prism portion) including the inclined side 22c (fifth side or sixth side) of the second cross-sectional portion 22a mainly optically transmits the traveling direction of incident light. It is a surface that is refracted in the thickness direction of the adjustment sheet, that is, a surface that has a function of condensing incident light (condensing surface). On the other hand, the surface of the linear optical structure 24 including the other inclined side 22d (fifth side or sixth side) of the second cross section 22a mainly suppresses color separation of the emitted light from the optical adjustment sheet. It is a surface (correction surface) that gives the function to perform. That is, in this example, the area of the condensing surface of the second linear prism portion located on the most base angle side (α1 side in FIG. 4) of the first linear prism portion is made larger than that of the first embodiment. .

  Thus, the utilization efficiency of incident light is improved by making the condensing surface of the 2nd linear prism part located in the most base angle side (alpha 1 side in FIG. 4) of the 1st linear prism part wider. Brightness can be increased. The reason is as follows. A light beam that passes through a surface of the first linear prism portion on which the second linear prism portion is formed (a surface including the second side 21c in FIG. 4; hereinafter also referred to as a second linear prism portion forming surface); That is, the light ray incident on the staircase surface of the optical adjustment sheet contains light ray components other than the luminance peak light ray 52, and the intensity (illuminance) of the light ray passing through the second linear prism portion forming surface of the first linear prism portion. ) Differs depending on the passing position of the second linear prism portion forming surface. Specifically, the intensity of the light beam passing through the second linear prism portion forming surface of the first linear prism portion is the base angle side of the first linear prism portion (the first base angle α1 side in FIG. 4). The closer it is, the bigger it becomes. That is, the intensity of the light incident on the second linear prism portion located on the base angle side of the first linear prism portion is higher (the illuminance is higher). Therefore, as in this example, by condensing the condensing surface of the second linear prism portion located closest to the base angle side of the first linear prism portion, it is possible to condense a light beam having a higher intensity. Therefore, the use efficiency of incident light can be improved and the luminance of outgoing light can be increased.

  On the other hand, as shown in FIG. 4, the second cross section 23a located on the apex angle 21e side of the first cross section 21a has a substantially triangular shape, and the inclined side 21c (second side) of the first cross section 21a. Are defined by a base 23b (fourth side) that is in parallel with each other and two inclined sides 23c and 23d that extend from both ends of the base 23b at predetermined angles (α2 and β3 in FIG. 4), respectively. Further, in this example, as shown in FIG. 4, the inclined side 23d (fifth side or sixth side) located on the apex angle 21e side of the first cross-sectional portion 21a is composed of two sides 23f and 23g, and the inclined side The side 23d was shaped to be bent convexly toward the outside of the second cross section 23a.

  Of the two sides 23f and 23g constituting the inclined side 23d, the side 23f located on the inclined side 21d side of the first cross-sectional portion 21a is, as shown in FIG. 4, from the apex angle 21e of the first cross-sectional portion 21a. It extends in parallel with the inclined side 21d of one cross section 21a. Therefore, the angle β3 of the angle (second base angle) between the base 23b and the inclined side 23d of the second cross-sectional portion 23a is α1 + β1. The other side 23g constituting the inclined side 23d is configured to be parallel to the inclined side 22d of the second cross-sectional portion 22a located on the first base angle side of the first cross-sectional portion 21a. That is, in this example, the inclined side 23c and the sides 23f and 23g that define the second cross-sectional portion 23a are the inclined side 22c of the second cross-sectional portion 22a and the inclined side 21d and the second cross-section of the first cross-sectional portion 21a, respectively. It is parallel to the inclined side 22d of the portion 22a. The angle α2 of the first base angle of the second cross section 23a was 30 degrees, and the angle β3 of the second base angle of the second cross section 23a was 96.85 degrees.

  In the second cross section 23a located on the apex angle 21e side of the first cross section 21a, the linear optical structure 24 (second linear prism) including the inclined side 23c (fifth side or sixth side). The surface of (part) is mainly a surface that refracts the traveling direction of incident light in the thickness direction of the optical adjustment sheet, that is, a surface having a function of condensing incident light (condensing surface). On the other hand, of the sides 23f and 23g that define the other inclined side 23d of the second cross section 23a, the side 23f located on the inclined side 21d side of the first cross section 21a is the inclined side of the first cross section 21a. Since it is parallel to 21d, the inclination direction of the surface of the linear optical structure 24 including the side 23f is substantially parallel to the luminance peak light ray 52. Therefore, the influence of refraction and reflection of incident light is small on the surface of the linear optical structure 24 including the side 23f. The surface of the linear optical structure 24 including the other side 23g that defines the inclined side 23d is mainly a surface (correction surface) that acts to suppress color separation of emitted light from the optical adjustment sheet. Become. Therefore, in this example, the shape of the second cross-sectional portion 23a increases the area of the condensing surface of the second linear prism portion corresponding to the second cross-sectional portion 23a as much as possible and makes the correction surface as small as possible. It has a shape like that.

  The optical properties of this example of the optical adjustment sheet having the above structure were evaluated in the same manner as in Example 1. Specifically, the optical adjustment sheet of this example is attached to the liquid crystal display device 100 and the backlight unit 6 shown in FIG. 3 (the optical adjustment of this example instead of the optical adjustment sheet 1 of Example 1 in FIG. 3). The front luminance was measured using a luminance meter. Moreover, the sensory evaluation of color was performed visually. The results are shown in Table 1 above.

  As can be seen from Table 1, when the optical adjustment sheet of this example was used, the front luminance was 112%, and it was found that the front luminance could be further increased than in the case of Example 1 (107%). . This is mainly because, in the optical adjustment sheet of this example, as described above, among the plurality of second linear prism parts constituting the linear optical structure, the most close to the base angle side of the first linear prism part. This is considered to be because the condensing surface of the second linear prism portion (linear structure corresponding to the second cross-sectional portion 22a) is wider than that of the first embodiment. In the optical adjustment sheet of this example, as described above, the correction surface of the second linear prism portion corresponding to the second cross-sectional portion 23a located on the apex angle 21e side of the first linear prism portion is smaller. However, as shown in Table 1, no significant difference was found between Examples 1 and 2 in terms of color uniformity. That is, it was confirmed that sufficient optical performance was obtained even when the optical adjustment sheet having the structure as in this example was used in various illumination devices including a liquid crystal backlight.

  In the optical adjustment member of the present invention, the color separation of the emitted light can be suppressed and the utilization efficiency of the incident light can be improved with one optical adjustment member. Therefore, the optical adjustment member of the present invention is particularly suitable as an optical member having a function of controlling the light directivity of an edge light type illumination device and a liquid crystal display device.

  In addition, since the liquid crystal display device and the illumination device of the present invention include the optical adjustment member of the present invention, the optical characteristics can be improved while reducing the thickness and cost of the device. Therefore, the liquid crystal display device and illumination device of the present invention are suitable for liquid crystal display devices and illumination devices for all uses.

DESCRIPTION OF SYMBOLS 1 Optical adjustment sheet 2 Light source 3 Light guide plate 4 Reflective sheet 5 Diffusion sheet 6 Illumination device 7 Liquid crystal display panel 10 Base material 11 1st linear prism part 11a 1st cross-section part 12 2nd linear prism part 12a 2nd cross-section part 12f Condensing surface 12r Correction surface 13 Linear optical structure 13b Step surface 13c Flat surface 52 Luminance peak rays 53 and 54 Refracted light 100 Liquid crystal display device

Claims (7)

An optical adjustment member to which light is incident from a predetermined direction,
A base material having a light incident surface on which the light is incident and having light transmittance;
A plurality of linear bodies having light transmissivity provided on a surface of the substrate opposite to the light incident surface;
The cross section perpendicular to the extending direction of the linear body has a triangular first cross section defined by the first to third sides, an area smaller than the first cross section, and the fourth to sixth sides. A substantially triangular second cross section defined, wherein the first side of the first cross section is in contact with the surface opposite to the light incident surface of the substrate, and the second cross section Is provided on the second side of the first cross section, and the fourth side of the second cross section is in contact with the second side of the first cross section,
The angle formed by the first side and the second side of the first cross section is smaller than the angle formed by the first side and the third side,
A color separation pattern of the light refracted on the surface of the linear body including the second side of the second cross section, and a color separation pattern of the light refracted on the surface of the linear body including the sixth side of the second cross section. However, the optical adjustment member has a reverse pattern with respect to the traveling direction of the light and cancels color separation from each other. An optical adjustment member to which light is incident from a predetermined direction,
A base material having a light incident surface on which the light is incident and having light transmittance;
A plurality of linear bodies, provided on a surface of the substrate opposite to the light incident surface, having light transmittance, and each having a condensing surface and a correction surface A linear body,
The cross section perpendicular to the extending direction of the linear body is substantially triangular, and one of the three sides defining the cross section is parallel to the surface opposite to the light incident surface of the substrate. One of the other two sides is stepped, and the stepped side is a line of intersection between the cross section, the light collection surface, and the correction surface, and the cross section The angle formed between the side parallel to the base material and the stepped side is smaller than the angle formed between the side parallel to the base material and the remaining side,
The light color separation pattern refracted on the light collecting surface of the linear body and the light color separation pattern refracted on the correction surface of the linear body are opposite to each other in the light traveling direction. An optical adjusting member characterized by forming a pattern and canceling color separation from each other. A lighting device,
A light source;
The optical adjustment member according to claim 1 or 2,
And a light guide plate for guiding the light emitted from the light source to the optical adjustment member.   The lighting device according to claim 3, wherein the optical adjustment member is disposed in contact with the light guide plate.   Furthermore, the illuminating device of Claim 3 or 4 provided with the reflection member arrange | positioned on the opposite side to the said optical adjustment member side of the said light-guide plate. A liquid crystal display device,
A light source;
The optical adjustment member according to claim 1 or 2,
A light guide plate for guiding the light emitted from the light source to the optical adjustment member;
A liquid crystal display device comprising: a liquid crystal display element disposed on a side opposite to the light guide plate side of the optical adjustment member.   The liquid crystal display device according to claim 6, wherein the optical adjustment member is disposed in contact with the light guide plate.

Images