JP2012252264A - Optical film and surface light source device - Google Patents

Abstract

An optical film capable of preventing partial adhesion without reducing luminance and preventing coloration due to spectroscopy.
A translucent base film having first and second main surfaces facing each other, and a deflection having a plurality of deflecting elements disposed on the first main surface and extending in one direction adjacent to each other. An element layer 2 and a protrusion layer 4 disposed on the second main surface and having a plurality of protrusions 5 and a plurality of optical elements 15 are provided. Each of the plurality of optical elements 15 has a height in the range of 0.01 μm to 2 μm, and the distance between adjacent optical elements is in the range of 3 μm to 100 μm, and each of the plurality of protrusions 5 has a height of 3 to 3 μm. In the range of 30 μm, the width at the half height position is in the range of 1 to 60 μm, and the distance between adjacent protrusions is in the range of 50 to 3000 μm.
[Selection] Figure 1

Description

  The present invention relates to an optical film for deflecting incident light and a surface light source device.

  In recent years, color liquid crystal display devices have been widely used in various fields such as mobile phones, portable notebook computers, portable liquid crystal televisions, and video integrated liquid crystal televisions. This liquid crystal display device basically includes a surface light source device and a liquid crystal display device. As the surface light source device, a direct method or an edge light method is used. In the direct type, a light source is provided directly under the liquid crystal display device. In the edge light system, a light source is disposed on a side surface portion of a light-transmitting flat light guide plate, and light is emitted from the entire surface of the light guide plate. 2. Description of the Related Art Edge light type surface light source devices are widely used because of the compactness of liquid crystal display devices.

  In the currently used surface light source device, the light emitted from the light source enters from the light incident surface on the side surface of the light guide plate and is guided into the light guide plate. The light deflected and reflected by the reflection groove provided on the reflection surface of the light guide plate is emitted from the emission surface of the light guide plate. A part of the light is emitted from the reflecting surface side, but is reflected by the reflector disposed so as to face the reflecting surface and is incident on the light guide plate again. The light emitted from the exit surface of the light guide plate is deflected by the optical film and is emitted almost vertically from the optical film. Furthermore, the light emitted from the optical film is diffused by the diffusion film and becomes a surface light source having the required viewing angle characteristics.

  When both the exit surface of the optical film and the entrance surface of the diffusion film are smooth, display defects called “wet out” and “Newton ring” are likely to occur due to partial adhesion between the smooth surfaces. “Wet out” means that when two films are in partial surface contact, a close contact area (area without an air layer) is visually recognized as a part different from a surrounding non-contact area (area with an air layer). It is a display defect. This is because the non-adherent region is affected by reflection and refraction at the film / air interface due to the presence of the air layer, whereas the adhering region is not affected by the air layer and the light transmission characteristics are different from the non-adherent region. Because.

  On the other hand, “Newton ring” is a display defect in which coloring and bright and dark stripes are visually recognized when the gap between two films is several μm or less. This is due to the slight difference in the gap between the two films (the thickness of the air layer), and due to light interference, the gap becomes brighter (stronger) at an even multiple of 1/4 wavelength of the light, and at an odd multiple. Because it becomes dark (weak). As a result, a light and dark difference depending on the wavelength of light appears, so that colored and light and dark stripes are visually recognized. The Newton ring is noticeably generated in the case of white light when the gap is 1.5 μm or less.

  In order to solve such a problem of deterioration in display quality, a technique has been proposed in which beads are dispersed in a resin used for an optical film, and protrusions are formed on the surface of the optical film facing the diffusion film (Patent Document 1). And 2). However, it is difficult to uniformly disperse the beads in the resin and to accurately control the height of the protrusions. In addition, the optical film and the resin of the beads have different compositions, and the optical film may be warped. Furthermore, since the beads dispersed in the resin become a light diffuser, there is a problem that the luminance is lowered.

  In addition, a technique has been proposed in which protrusions are formed on the back surface of an optical film in which deflecting elements of isosceles triangular prisms having a substantially right angle are arranged on the surface at intervals of about 50 μm so as not to generate Newton rings ( (See Patent Document 3). In Patent Document 3, a base film part, a deflecting element part, and a protruding part are integrally formed. Generally, when a prism part and a protrusion part are integrally formed on a base film, the shape is transferred to the base film by thermal transfer. However, thermal transfer to a base film using a high-strength resin has poor shape transferability. For this reason, the deflection element formed by thermal transfer deviates from the design shape.

  In particular, by setting the interval between the deflection elements to 10 μm or less, the angular distribution of the emitted light can be narrowed using the diffraction phenomenon. As a result, the front luminance of the surface light source device can be improved. When forming a deflection element having a spacing and height of about 5 μm to 10 μm on a high-strength base film by thermal transfer, the tip of the deflection element is rounded, and a deflection element lower by about 0.3 μm to 1 μm than the design value is formed. End up. On the other hand, if a resin with good shape transferability is used, deviation from the design shape can be reduced to 0.2 μm or less. However, generally, a resin having good shape transferability is not suitable as a base film for an optical film because it has no strength. Thus, conventionally, it has been difficult to realize a high-luminance surface light source device that can prevent wet-out and Newton's ring due to partial adhesion between two films.

  Furthermore, when an optical film using diffraction / interference phenomenon based on wave optics is used, there is a problem that light emitted from the optical film appears to be colored in a rainbow color by spectroscopy (see Patent Document 4). This defect is a peculiar defect that does not appear in the prism sheet using the conventional refraction / total reflection phenomenon based on geometric optics.

JP 2007-249220 A Japanese Patent No. 003968155 JP 09-021907 A Japanese Patent No. 004265602

  The present invention provides an optical film and a surface light source device capable of preventing wet-out and Newton's ring due to partial adhesion between two films without reducing luminance and preventing coloration due to spectroscopy. It is the purpose.

  To achieve the above object, according to a first aspect of the present invention, there is provided a translucent base film having first and second main surfaces facing each other and a first main surface disposed adjacent to each other in one direction. Each of the plurality of optical elements has a height of 0.01 μm to 2 μm. The distance between adjacent optical elements is in the range of 3 μm to 100 μm, and each of the plurality of protrusions has a height in the range of 3 to 30 μm and a width at a half position of the height of 1 to 60 μm. The gist is that the distance between adjacent protrusions is in the range of 50 to 3000 μm.

  According to a second aspect of the present invention, a light source and an end surface facing the light source are an incident surface, and each of a pair of main surfaces orthogonal to the incident surface is a reflective surface and an output surface. A light guide plate having a reflective element that reflects the light incident thereon through the light exit surface, the optical film according to the first aspect of the present invention disposed to face the light exit surface, and the light exit surface across the optical film, The gist of the present invention is a surface light source device that includes an opposing diffusion film and a reflector that is disposed to face the reflecting surface and allows light emitted from the reflecting surface to enter the light guide plate.

  According to the present invention, there are provided an optical film and a surface light source device capable of preventing wet-out and Newton's ring due to partial adhesion between two films without reducing luminance and preventing coloration due to spectroscopy. be able to.

It is a section schematic diagram showing an example of a surface light source device concerning an embodiment of the invention. It is a top view which shows an example of the light-guide plate used for the surface light source device which concerns on embodiment of this invention. It is a figure which shows the AA cross section of the light-guide plate shown in FIG. It is a figure which shows an example of the entrance plane of the light-guide plate used for the surface light source device which concerns on embodiment of this invention. It is a figure which shows the other example of the entrance plane of the light-guide plate used for the surface light source device which concerns on embodiment of this invention. It is a figure which shows the other example of the entrance plane of the light-guide plate used for the surface light source device which concerns on embodiment of this invention. It is a figure which shows the other example of the entrance plane of the light-guide plate used for the surface light source device which concerns on embodiment of this invention. It is a figure which shows an example of the reflective element of the light-guide plate used for the surface light source device which concerns on embodiment of this invention. It is a figure which shows the other example of the reflective element of the light-guide plate used for the surface light source device which concerns on embodiment of this invention. It is a figure which shows an example of the propagation of the light in the light-guide plate used for the surface light source device which concerns on embodiment of this invention. It is a figure which shows the other example of the light-guide plate used for the surface light source device which concerns on embodiment of this invention. It is a figure which shows the optical film used for a surface light source device. It is a figure which shows the BB cross section of the optical film shown in FIG. It is a figure which shows the surface light source device using the optical film shown in FIG. It is a figure which shows an example of arrangement | positioning of an optical film and a light-guide plate. It is a figure which shows the other example of arrangement | positioning of an optical film and a light-guide plate. It is a figure which shows an example of propagation of the light in a light-guide plate and an optical film. It is a figure which shows an example of the optical film which concerns on embodiment of this invention. It is a figure which shows CC cross section of the optical film shown in FIG. It is a figure which shows an example of the optical element of the optical film which concerns on embodiment of this invention. It is a figure which shows the other example of the optical element of the optical film which concerns on embodiment of this invention. It is a figure which shows the other example of the optical element of the optical film which concerns on embodiment of this invention. It is a figure which shows DD cross section of the optical film shown in FIG. It is a figure which shows the other example of the optical element of the optical film which concerns on embodiment of this invention. It is a figure which shows the EE cross section of the optical film shown in FIG. It is a figure which shows the other example of the optical element of the optical film which concerns on embodiment of this invention. It is a figure which shows the other example of the optical element of the optical film which concerns on embodiment of this invention. It is a figure which shows the FF cross section of the optical film shown in FIG. It is a figure which shows an example of the protrusion of the optical film which concerns on embodiment of this invention. It is a figure which shows the other example of the protrusion of the optical film which concerns on embodiment of this invention. It is a figure which shows an example of the relationship between the emission angle of the surface light source device which concerns on embodiment of this invention, and a brightness | luminance. It is a table | surface which shows an example of the evaluation result of the partial adhesion | attachment and coloring of the surface light source device which concerns on embodiment of this invention. It is a figure (the 1) which shows an example of the manufacturing method of the optical film which concerns on embodiment of this invention. It is a figure (the 2) which shows an example of the manufacturing method of the optical film which concerns on embodiment of this invention. It is sectional drawing which shows an example of the deflection | deviation element of the optical film which concerns on embodiment of this invention.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  Further, the following embodiments exemplify apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention is the material, shape, structure, The layout is not specified as follows. The technical idea of the present invention can be variously modified within the scope of the claims.

  As shown in FIG. 1, the surface light source device according to the embodiment of the present invention includes a light source 10, a light guide plate 7, an optical film 6, a diffusion film 8, and a reflector 9. The light source 10 is disposed to face the incident surface of the light guide plate 7. The light guide plate 7 has a reflective surface on which a plurality of reflective elements 14 are arranged. The reflection element 14 reflects the light incident from the light source 10 so as to go toward the emission surface 12.

  The optical film 6 has translucency and includes a base film 1, a deflection element layer 2, and a protruding layer 4. The base film 1 has a first main surface and a second main surface that face each other. The deflection element layer 2 is disposed on the first main surface of the base film 1 so as to face the emission surface 12 of the light guide plate 7. The protruding layer 4 is disposed on the second main surface of the base film 1.

  The deflection element layer 2 includes a plurality of deflection elements 3 extending in one direction adjacent to each other. The deflecting element 3 polarizes light incident on the optical film 6 from the emission surface 12 of the light guide plate 7 and emits the light almost vertically from the second main surface of the optical film 6.

  The protruding layer 4 includes a plurality of protrusions 5 and a plurality of optical elements 15. The protrusion 5 prevents partial adhesion with the diffusion film 8. The optical element 15 diffuses light emitted from the optical film 6.

  The diffusion film 8 faces the emission surface 12 of the light guide plate 7 with the optical film 6 interposed therebetween. The diffusion film 8 diffuses the light incident from the optical film 6 so as to have a desired viewing angle characteristic. The reflector 9 is disposed facing the reflection surface 13 of the light guide plate 7. The reflector 9 reflects light emitted from the reflection surface of the light guide plate 7 toward the light guide plate 7.

  More specifically, as shown in FIGS. 2 and 3, the light guide plate 7 has a substantially plate shape having a pair of substantially rectangular main surfaces. An end surface of the light guide plate 7 facing the light source 10 is defined as an incident surface 11. A pair of main surfaces of the light guide plate 7 orthogonal to the incident surface 11 are defined as a reflective surface 13 and an output surface 12, respectively. The plurality of reflecting elements 14 arranged on the reflecting surface 13 reflects the light incident from the light source 10 through the incident surface 11 so as to go toward the emitting surface 12.

  As the light source 10, a plurality of light emitting diodes are used. In FIG. 2, four light emitting diodes are used, but the number of light emitting diodes is not limited. In addition, although a fluorescent tube such as a cold cathode tube can be used as the light source 10, a light emitting diode having a short light emitting surface is desirable for thinning the surface light source device.

  As the material of the light guide plate 7, transparent materials such as polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), polyolefin (PO), polycarbonate (PC), and acrylic can be used. Also, other materials than the above can be used as long as they are transparent materials having a constant refractive index as described above.

  Light emitted from a plurality of light sources 10 arranged linearly at substantially equal intervals so as to face the incident surface 11 of the light guide plate 7 enters the light guide plate 7 from the incident surface 11. By forming a deflecting element extending in the thickness direction of the light guide plate 7 as a light control unit on the incident surface 11, it is possible to diffuse light near the incident surface 11 or to control the traveling direction of the light. In particular, it is possible to improve the display quality due to the difference in brightness near the entrance surface 11. As shown in FIGS. 4 to 7, the light control unit of the incident surface 11 has a substantially triangular (FIG. 4), a substantially trapezoidal (FIG. 5), a substantially semi-elliptical shape (FIG. 6), or a smooth wave shape. A deflecting element having a shape (FIG. 7) is used. 4 to 7 having a fine uneven shape formed on the surface of the deflecting element is relatively easy to manufacture and easily obtains the effect of light control.

  A groove-like reflecting element 14 that is a light control unit for changing the traveling direction of light is formed on the reflecting surface 13. The reflective element 14 has a substantially triangular cross section, and its ridgeline extends in a direction substantially parallel to the incident surface 11. The ridge line of the reflective element 14 is linear. A plurality of reflecting elements 14 are continuously formed from the incident surface 11 to the surface facing the incident surface 11. The reflective element 14 may be formed on the emission surface 12. In this case, the reflecting surface 13 is a flat surface. Moreover, the ridgeline of the reflective element 14 may be curved.

  The interval between the adjacent reflective elements 14 may be constant, or may be changed depending on the distance from the incident surface 11. When the interval between the adjacent reflecting elements 14 is constant, the amount of light emitted from the vicinity of the surface facing the incident surface 11 is less than the amount of light emitted from the vicinity of the incident surface 11 out of the light emitted from the emission surface 12. There is a risk of becoming. In this case, the amount of light emitted from the vicinity of the surface facing the incident surface 11 can be increased by increasing the distance between the reflecting elements 14 as the distance from the incident surface 11 increases. By adjusting the interval between the adjacent reflective elements 14, the position distribution of the intensity of light emitted from the light guide plate 7 can be adjusted, and a surface light source device having uniform emission characteristics within the surface can be realized.

  As shown in FIG. 8, the reflective element 14 is arranged at a period p on the reflective surface 13 of the light guide plate 7 having a thickness a. The reflective element 14 includes a first inclined surface 14 a on the incident surface 11 side and a second inclined surface 14 b on the surface side facing the incident surface 11 of the light guide plate 7. With respect to the emission surface 12, the first inclined surface 14a has an inclination angle α1, and the second inclined surface 14b has an inclination angle α2. The inclination angles α1 and α2 may be constant for all the reflection elements 14 or may be different for some or all of the reflection elements 14.

  The period p of the reflective element 14 is, for example, in the range of 1 μm to 1000 μm, preferably 5 μm to 500 μm, more preferably 10 μm to 200 μm, still more preferably 20 μm to 150 μm, and still more preferably 67 μm to 81 μm. The inclination angle α1 is, for example, 0.01 ° to 5 °, preferably 0.05 ° to 2 °, more preferably 0.1 ° to 0.8 °, still more preferably 0.15 ° to 0.65 °, Even more preferably, it is in the range of 0.25 ° to 0.55 °. The inclination angle α2 is, for example, 70 ° to 90 °, preferably 75 ° to 85 °, more preferably 78 ° to 83 °, still more preferably 79.35 ° to 79.85 °, and still more preferably 79.45 °. It is in the range of ˜79.75 °. The thickness a of the light guide plate 7 is, for example, 0.04 mm to 5 mm, preferably 0.05 mm to 3 mm, more preferably 0.1 mm to 1 mm, still more preferably 0.15 mm to 0.6 mm, and still more preferably 0. It is in the range of 2 mm to 0.4 mm.

  Further, as shown in FIG. 9, a flat portion may be provided between adjacent reflecting elements 14. The groove-shaped reflective elements 14 having a width pa are arranged with a period pb. By providing the flat portion, the position distribution of the intensity of the light emitted from the light guide plate 7 can be adjusted, and a surface light source device having uniform emission characteristics within the surface can be realized. A flat portion may be provided on the bottom surface of the groove of the reflective element 14.

  As shown in FIG. 10, the first inclined surface 14 a transmits light incident on the exit surface 12 where the reflecting element 14 is not formed from the entrance surface 11 at an angle ψ1 with the normal of the exit surface 12. Reflected so as to have an angle ψ2 with respect to the normal. That is, the light traveling at an angle with respect to the normal of the exit surface 12 is reflected by the first inclined surface 14a, thereby reducing the angle formed with the normal of the exit surface 12. By repeating the reflection on the first inclined surface 14 a, light whose angle formed with the normal line of the emission surface 12 at the position X of the emission surface 12 is smaller than the critical angle is emitted from the emission surface 12. Thus, as shown in FIG. 10, the light incident on the incident surface 11 of the light guide plate 7 from the light source 10 until the angle formed with the normal line of the output surface 12 reaches a critical angle, the output surface 12 and the reflective surface 13. Then, the light guide plate 7 is advanced while repeating total reflection.

  In the light guide plate 7 in which the groove-shaped reflection element 14 is formed on the reflection surface 13 as described above, the inclination angle α1 of the first inclined surface 14a is smaller than the inclination angle α2 of the second inclined surface 14b. Accordingly, since most of the reflective element 14 is used for light reflection, the efficiency of reflecting the light incident on the light guide plate 7 toward the exit surface 12 is high, and the light utilization efficiency is high.

  As shown in FIG. 11, a plurality of anisotropic diffusions having a substantially triangular cross section and a ridge line extending parallel to each other from the incident surface 11 toward the surface facing the incident surface 11 are formed on the light emitting surface 12 of the light guide plate 7. The pattern 30 may be formed. The interval between adjacent anisotropic diffusion patterns 30 is in the range of 1 μm to 1000 μm, preferably 5 μm to 300 μm, more preferably 10 μm to 200 μm, still more preferably 15 μm to 100 μm, and even more preferably 20 μm to 81 μm. Further, a hologram pattern may be used as the anisotropic diffusion pattern 30. Note that when the reflective element 14 is formed on the emission surface 12, the anisotropic diffusion pattern 30 is formed on the reflective surface 13.

  The anisotropic diffusion pattern 30 is effective in obtaining uniform emission characteristics within the emission surface 12 of the light guide plate 7. In particular, in the vicinity of the incident surface 11 of the light guide plate 7, there is an effect of reducing the difference in the light emission intensity in the vicinity of the light source 10 and between the adjacent light sources 10, and it has uniform emission characteristics within the surface. A surface light source device with high display quality can be realized.

  As shown in FIGS. 12 and 13, the optical film 6 a includes a base film 1 and a deflection element layer 2. The deflecting element layer 2 includes a base layer having a thickness h2 and a plurality of prism-shaped deflecting elements 3 formed on the base layer. The deflection elements 3 extend in one direction adjacent to each other. The deflection element 3 is arranged with a height h1 and a period d1. The cross-sectional shape of the deflection element 3 is a triangle, and the ridge line is a straight line. In a cross section cut in a direction perpendicular to the extending direction of the deflecting element 3, an angle formed between the normal from the apex and the first inclined surface 3a on the incident surface 11 side of the deflecting element 3 and the second inclined surface 3b on the opposite side. Are β1 and β2, respectively. The deflection element 3 may have a substantially elliptical shape or a substantially trapezoidal cross section, and the ridgeline may be curved. Adjacent deflection elements 3 may be separated from each other. However, if the deflecting elements 3 are arranged in contact with each other, light can be deflected better, and the luminance of the surface light source device becomes higher.

  As the base film 1, a single transparent material such as polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), polyolefin (PO), polycarbonate (PC), acrylic, etc., or a combination of two or more types can be used. As the deflection element layer 2, a light-transmitting photocurable resin such as urethane acrylate resin, oligoester acrylate resin, epoxy acrylate resin, silicon acrylate resin, acrylic acrylate resin, or polyester acrylate resin is used.

  The optical film 6a is required to have emission characteristics such as a narrow angle distribution of the emitted light, emission of the emitted light almost vertically with a narrow angle distribution, and an increase in luminance of the emitted light. In order to realize such an emission characteristic, the thickness h2 of the base layer of the deflection element layer 2, the height h1 of the deflection element 3, the period d1, in consideration of the workability of the mold used for molding the optical film 6a, The angles β1, β2, etc. of the first and second inclined surfaces are determined.

  For example, if the thickness h2 of the base layer of the deflecting element layer 2 is set to approximately 0 μm, the material used for the deflecting element layer 2 can be reduced, and thus the manufacturing cost can be suppressed. In addition, the total thickness of the surface light source device can be reduced. On the other hand, if the thickness h2 is greater than 0 μm, it is possible to suppress deformation due to contamination of foreign matter when forming the deflection element 3, and it is possible to prevent deterioration in display quality of the surface light source device. Therefore, it is desirable that the thickness h2 be practically set to a minimum thickness that can suppress deformation of the deflection element 3 due to contamination of foreign matter. In addition, when there is a variation in thickness during manufacturing, it is desirable to increase the thickness h2 in consideration of the variation.

  The thickness h2 of the base layer of the deflection element layer 2 is, for example, in the range of 2 μm to 20 μm, preferably 2.5 μm to 16 μm, more preferably 3 μm to 14 μm, still more preferably 4 μm to 12 μm, and even more preferably 5 μm to 10 μm. is there.

  The height h1 of the deflecting element 3 is, for example, 3 μm to 100 μm, preferably 3.5 μm to 50 μm, more preferably 4 μm to 20 μm, still more preferably 5 μm to 10 μm, and even more preferably 5.4 μm to 6.4 μm. It is a range. The period d1 is, for example, in the range of 3 μm to 50 μm, preferably 3.5 μm to 30 μm, more preferably 4.5 μm to 15 μm, still more preferably 4.9 μm to 10.1 μm, and even more preferably 4.9 μm to 5.1 μm. It is.

  The angle β1 of the first inclined surface 3a of the deflection element 3 is, for example, 0 ° to 30 °, preferably 4 ° to 20 °, more preferably 6 ° to 16 °, still more preferably 8 ° to 12 °, and still more preferably. Is in the range of 9.8 ° to 10.8 °. The angle β2 of the second inclined surface 3b is, for example, 10 ° to 60 °, preferably 20 ° to 50 °, more preferably 30 ° to 40 °, still more preferably 34 ° to 38 °, and still more preferably 35.5. It is in the range of ° to 36.5 °.

  Further, as the deflecting element 3, for example, a deflecting element having a sawtooth cross section, a length of two sides sandwiching the tip of each tooth being different by 10% or more, and a depression angle of 60 ° or less may be used. When the refractive index of the optical material of the deflection element is n, the deflection element has an average depth h of h = α × d / (n−1) (provided that 0.4 ≦ α ≦ 1.0, It is desirable that d is an average period of the deflecting element. 0.46 μm ≦ λ1 ≦ 0.50 μm, 0.53 μm ≦ λ2 ≦ 0.57 μm, 0.60 μm ≦ λ3 ≦ 0.64 μm, and light of three wavelengths λ1, λ2, λ3 is 15 degrees ≦ γ1 ≦ 70 degrees When it is designed so that the diffraction angle that maximizes the diffraction efficiency of each wavelength is included in the range of -5 degrees to +5 degrees when incident at an angle γ1 within the range of A device can be obtained.

  Further, as the deflecting element 3, for example, a deflecting element having a shape made of a groove or a mountain having an average period of 200 μm or less constituting a hologram may be used. The hologram bends white light with an incident angle of 30 ° ± 15 ° in a direction perpendicular to the surface of the optical film where no deflection element is formed. When the refractive index of the optical material of the deflection element is n, the deflection element has an average period of 5.0 ± 1.0 μm and an average depth of (3.7 ± 1.0) / (n−1) μm. It is desirable to have a certain sawtooth shape or a shape in which a sawtooth-shaped groove is filled by less than 50% of the depth. When the deflection element is designed so that the average period d of the deflecting element and the position deviation u of the sawtooth crest are in the range of u / d ≦ 0.2, a high-luminance surface light source device can be obtained.

  As shown in FIG. 14, in the surface light source device, the optical film 6 a is installed so that the deflection element layer 2 faces the emission surface 12 of the light guide plate 7. As shown in FIG. 15, the optical film 6 a is installed such that the ridge line of the deflection element 3 is substantially parallel to the ridge line of the reflection element 14 formed on the light guide plate 7. Alternatively, as illustrated in FIG. 16, the ridge line of the deflecting element 3 may be tilted at a predetermined angle with respect to the ridge line of the reflective element 14. In this case, the deflecting element 3 is installed so that the first inclined surface 3a faces the incident surface 11 side. By tilting the ridge line of the deflecting element 3 with respect to the ridge line of the reflecting element 14 at a predetermined angle, a liquid crystal display is disposed between the light guide plate 7 and the optical film 6a or on the emission side of the optical film 6a and the surface light source device. Moire interference fringes are less likely to occur with the apparatus.

  As shown in FIG. 17, most of the light emitted from the emission surface 12 of the light guide plate 7 has a small angle with the emission surface 12. Lights L1 and L2 emitted at angles γ1 and γ2 formed with the emission surface 12 enter the optical film 6a from the first inclined surface 3a of the deflection element 3. The incident lights L1 and L2 are reflected by the second inclined surface 3b and deflected at an angle close to perpendicular to the upper surface of the optical film 6a. Therefore, the light Lo1 and Lo2 deflected at angles γo1 and γo2 that are nearly perpendicular to the upper surface of the optical film 6a are emitted from the optical film 6a. As a result, the optical film 6a improves the front intensity of the light emitted from the surface light source device.

  It should be noted that the following precautions are required for light deflection by the optical film 6a. When the distance between the adjacent deflection elements 3 of the optical film 6a is sufficiently large, the shape and distance of the deflection element 3 may be designed based on the light refraction / total reflection phenomenon. On the other hand, when the distance between adjacent deflecting elements 3 of the optical film 6a is about 10 μm or less, it is necessary to design the shape and distance of the deflecting element 3 in consideration of the light diffraction / interference phenomenon. (For example, refer to JP 2006-58844 A).

  For example, in the optical film 6a, in consideration of the light diffraction phenomenon, the period d1 of the deflecting element 3 shown in FIG. 17 is in the range of 4.9 μm to 5.1 μm, and the angle β1 is 9.8 ° to 10.8 °. And the angle β2 is in the range of 35.5 ° to 36.5 °. By using the optical film 6a designed in this way, the front luminance of the surface light source device can be improved.

  The optical film 6a and the diffusion film 8 are actually arranged close to each other. When both the upper surface of the optical film 6a and the incident surface of the diffusion film 8 are smooth, the optical film 6a and the diffusion film 8 are partially adhered. For this reason, display defects such as wet out and Newton rings occur, and the display quality deteriorates. In addition, light is diffracted by the deflecting element 3, and the problem of coloring in rainbow is likely to occur.

  As shown in FIGS. 18 and 19, the optical film 6 according to the embodiment is provided with a protruding layer 4 on the opposite surface of the base film 1 on which the deflection element layer 2 is formed. The protrusion layer 4 includes a plurality of protrusions 5 having a height Hr1, a half-value width Dr, and a plurality of optical elements 15 having a height Hr2 formed on the base layer having a thickness Hr0. The protrusions 5 are arranged at a distance Pr1 between adjacent protrusions 5. The optical elements 15 are arranged at a distance Pr2 between the adjacent optical elements 15. The “half-value width” is the maximum diameter at the cut when the protrusion 5 is cut at a position half the height Hr1 of the protrusion 5.

  As the protrusion layer 4, a light-transmitting photocurable resin such as urethane acrylate resin, oligoester acrylate resin, epoxy acrylate resin, silicon acrylate resin, acrylic acrylate resin, polyester acrylate resin, or the like is used.

  For example, if the thickness Hr0 of the base layer of the projecting layer 4 is reduced to about 0.1 μm, the material used for the projecting layer 4 can be reduced, so that the manufacturing cost can be suppressed. In addition, the total thickness of the surface light source device can be reduced. On the other hand, if the thickness Hr0 is made thicker than about 0.1 μm, it is possible to suppress deformation due to contamination of foreign matters when forming the projection layer 4, and thus it is possible to prevent the display quality of the surface light source device from deteriorating. Therefore, it is desirable that the thickness Hr0 be practically set to a minimum thickness that can suppress deformation due to contamination of foreign matters when the protruding layer 4 is formed. If there is a variation in thickness during production, it is desirable to increase the thickness Hr0 in consideration of the variation. The thickness Hr0 is, for example, in the range of 2 μm to 20 μm, preferably 2.5 μm to 16 μm, more preferably 3 μm to 14 μm, still more preferably 4 μm to 12 μm, and even more preferably 5 μm to 10 μm.

  The optical element 15 prevents iridescent coloring by diffusing light emitted from the optical film 6. The haze value of the optical film 6 having the optical element 15 is, for example, in the range of 10 to 80, preferably in the range of 15 to 70, and more preferably in the range of 20 to 60. When the haze value is less than 10%, it becomes difficult to eliminate the rainbow color. When the haze value exceeds 80, the directivity and peak luminance of light emitted from the optical film 6 are reduced. In addition, a haze value represents the cloudiness of a film, is calculated | required from the ratio (%) with respect to the total light transmitted light of diffuse transmitted light, and is measured with a haze meter.

  The height Hr2 of the optical element 15 is, for example, in the range of 0.01 μm to 2 μm, preferably 0.02 μm to 1.5 μm. When the height Hr2 is smaller than 0.01 μm, the diffusion of light by the optical element 15 becomes small, and the haze value becomes smaller than 10. When the height Hr2 exceeds 2 μm, the diffusion of light by the optical element 15 becomes large, and the haze value becomes larger than 80.

  The distance Pr2 between the adjacent optical elements 15 is, for example, in the range of 3 μm to 100 μm, preferably 5 μm to 50 μm. When the distance Pr2 of the optical element 15 is larger than 100 μm, the diffusion of light by the optical element 15 becomes small, and the haze value becomes smaller than 10. When the distance Pr2 is smaller than 3 μm, light diffraction by the optical element 15 becomes strong, and iridescent coloring is likely to occur.

  As the optical element 15, for example, a lens, a cone, a pyramid, or the like is used. Alternatively, fine irregularities formed in a satin shape on the surface of the protruding layer 4 may be used as the optical element 15. In particular, when a lens is used as the optical element 15, it is possible to suppress the deterioration of light emission characteristics such as directivity and luminance, and to improve the diffusion performance of emitted light. Further, by using a lens as the optical element 15, optical design or mold processing is facilitated. Furthermore, when the optical elements 15 are regularly arranged and used, optical design or mold processing becomes easier.

  When a lens is used as the optical element 15, a lens having a radius of curvature of, for example, a range of 0.1 mm to 0.3 mm, preferably a range of 0.15 mm to 0.25 mm is used. When the curvature radius of the lens is smaller than 0.1 mm, the haze value is smaller than 10. If the radius of curvature of the lens is greater than 0.3 mm, the haze value will be greater than 80.

  For example, as shown in FIG. 20, when a plurality of lenses as the optical element 15 are arranged on the surface of the protruding layer 4 at regular intervals in a lattice shape, optical design and mold processing are facilitated. In the arrangement shown in FIG. 20, there are flat portions between the optical elements 15, and the diffusion performance of the emitted light may be insufficient. In such a case, as shown in FIG. 21, a plurality of lenses as the optical element 15 may be spread on the surface of the projection layer 4 excluding the portion where the projections 5 are arranged without any gaps.

  Further, as shown in FIGS. 22 and 23, optical elements 15 including two types of lenses 150 and 152 having different radii of curvature may be arranged at regular intervals in a lattice shape. For example, the lens 150 has a radius of curvature of 0.1 mm to 0.3 mm and a diameter of 3 μm to 100 μm. The lens 152 has a radius of curvature in the range of 10 μm to 200 μm and a diameter in the range of 1 μm to 50 μm. By using the lenses 150 and 152 having different radii of curvature, desired haze values and light emission characteristics can be obtained. The lenses having different curvature radii are not limited to two types, and may be three or more types.

  Since the plurality of optical elements shown in FIGS. 20 to 22 are arranged in a straight line, there may be a difference in brightness between the lens position and the inter-lens position, for example. Therefore, there is a risk that the striped pattern is visually observed or moire occurs between the liquid crystal panel and the like. In such a case, as shown in FIG. 24, a plurality of optical elements 15 having a hexagonal planar shape may be spread on the surface of the protruding layer 4 without any gaps. As shown in FIGS. 24 and 25, each optical element 15 includes a hexagonal lens 154 and a pentagonal lens 156 in contact with each side of the lens 154. Since the boundary between the optical elements 15 is not linear, it is possible to prevent striped patterns and moire. The shape of the lens included in the optical element 15 is not limited and may be an arbitrary polygon. The optical element 15 may include a plurality of types of polygonal lenses.

  The diffraction of light by the deflection element 3 shown in FIGS. 18 and 19 occurs in a direction orthogonal to the extending direction of the deflection element 3. Iridescent coloring also occurs in a direction orthogonal to the extending direction of the deflecting element 3. Therefore, the light may be strongly diffused by the optical element 15 in the direction orthogonal to the extending direction of the deflecting element 3. For example, as shown in FIG. 26, a lens having a length that is larger in the direction orthogonal to the extending direction of the deflecting element 3 than the extending direction of the deflecting element 3 may be used. As shown in FIGS. 27 and 28, a semi-cylindrical lens that extends in a direction orthogonal to the extending direction of the deflection element 3 may be used as the optical element 15.

  The protrusion 5 can prevent partial adhesion between the optical film 6 and the diffusion film 8. The protrusion 5 has a cylindrical shape, a conical shape, a triangular prism shape, a triangular pyramid shape, a quadrangular prism shape, a quadrangular pyramid shape, or a hemispherical shape. In order to prevent partial adhesion between the optical film 6 and the diffusion film 8, it is desirable that the contact area of the protrusions 5 be small. For example, the area of the tip portion can be reduced in a shape having a sharp tip as shown in FIG. 30 rather than a shape having a gentle tip as shown in FIG. Therefore, the projection 5 is more effective in a hemispherical shape or a cone shape than a columnar shape. A plurality of projections and depressions formed in a minute area may be used as the protrusion 5.

  The height Hr1 of the protrusion 5 is, for example, in the range of 3 μm to 30 μm, preferably 4 μm to 20 μm, more preferably 5 μm to 16 μm, still more preferably 7 μm to 13 μm, and even more preferably 9 μm to 12 μm. The protrusion 5 is intended to create a gap between the optical film 6 and the diffusion film 8. However, since it is desired to make the surface light source device thin, it is not preferable that the height Hr1 of the protrusion 5 be higher than 30 μm. On the other hand, if the height Hr1 of the protrusions 5 is less than 3 μm, the gap becomes narrow, and the optical film 6 and the diffusion film 8 are partially brought into close contact just by lightly pressing the surface light source device from the surface.

  The half width Dr of the protrusion 5 is, for example, in the range of 1 μm to 60 μm, preferably 4 μm to 40 μm, more preferably 5 μm to 30 μm, still more preferably 6 μm to 20 μm, and still more preferably 10 μm to 17 μm. In the protrusion 5 having a wide half-value width Dr, the contact area between the optical film 6 and the diffusion film 8 tends to be wide, and partial adhesion tends to occur. On the other hand, it is difficult to form the protrusion 5 with the half width Dr narrowed without changing the height Hr1, and the strength of the protrusion 5 is weakened and easily broken.

  The distance Pr1 between the adjacent protrusions 5 is, for example, in the range of 50 μm to 3000 μm, preferably 75 μm to 1000 μm, more preferably 100 μm to 500 μm, still more preferably 240 μm to 350 μm, and even more preferably 285 μm to 295 μm. If the distance Pr1 of the protrusions 5 is too larger than 3000 μm, the optical film 6 or the diffusion film 8 will bend and come into contact with each other, making it easy to partially adhere. If the distance Pr1 is less than 50 μm, the amount of light scattered by the protrusions 5 cannot be ignored, the optical film 6 becomes clouded, the emitted light from the optical film 6 becomes dark, or the emission angle distribution of the emitted light changes. End up.

  In addition, optical films that increase brightness have been proposed (see, for example, Japanese Patent No. 4265602 and Japanese Patent No. 4240037). In the proposed optical film, a transmission diffraction grating and a hologram optical element are formed. Forming a plurality of protrusions on the surface opposite to the surface on which the transmissive diffraction grating and the hologram optical element are formed is very effective for realizing a high-luminance surface light source device with good appearance.

  However, in the example of the liquid crystal display device described in Japanese Patent No. 4240037, two optical films are used. On the other hand, in the surface light source device according to the embodiment, high luminance can be realized without using only one optical film 6. Thus, the embodiment can contribute to the reduction of the number of members and the reduction in the thickness of the surface light source device.

  As shown in FIG. 1, the optical film 6 is installed in such a direction that the deflection element layer 2 on which the deflection element 3 is formed faces the emission surface 12 of the light guide plate 7. As shown in FIG. 15 or FIG. 16, the ridge line of the deflection element 3 is substantially parallel to the ridge line of the reflection element 14 formed on the light guide plate 7 or inclined at a predetermined angle. Further, the deflecting element 3 is installed so that the first inclined surface 3a side (see FIG. 19) faces the incident surface 11 side. By tilting the ridge line of the deflecting element 3 with respect to the reflecting element 14 by a predetermined angle, moire interference fringes are less likely to occur between the light guide plate 7 and the optical film 6 or between the optical film 6 and the liquid crystal display device. In some cases.

  In the surface light source device according to the embodiment, the protrusion 5 and the optical element 15 are formed on the upper surface of the optical film 6. Therefore, even if the incident surface of the diffusion film 8 is smooth, the optical film 6 and the diffusion film 8 do not partially adhere to each other. Further, the emitted light is diffused by the optical element, and the diffraction by the deflecting element 3 can be weakened. As a result, the display quality of the surface light source device can be kept good.

  The protrusions 5 are regularly and periodically arranged. In particular, the lattice-like arrangement is easy to design. When the protrusions 5 are arranged in a lattice shape, the unit lattice may be a square, a rectangle, a parallelogram, or the like. Further, if the direction in which the protrusions 5 are arranged is arranged in parallel to the ridge line of the deflection element 3 of the optical film 6, the design is relatively easy. When the projection 5 and the deflection element 3 or the projection 5 and the liquid crystal display device interfere with each other to generate an interference fringe, the direction in which the projection 5 is arranged is inclined by a predetermined angle with respect to the ridge line of the deflection element 3 of the optical film 6. Can eliminate the interference.

  FIG. 31 shows the result of measuring the light emission angle distribution by removing the diffusion film 8 in the surface light source device shown in FIG. As a comparison, the light emission angle distribution of the surface light source device using the optical film 6a that does not form the protruding layer shown in FIG. 14 is also shown. In the deflecting element 3, both the optical films 6 and 6a have an angle β2 = 36 ° of the second inclined surface 3b, an angle β1 = 10.3 ° of the first inclined surface 3a, and a period d1 = 5 μm. In the optical film 6 on which the protrusion layer 4 is formed, the protrusion 5 has a half width Dr = 13 μm, a distance Pr1 = 290 μm, and a height Hr1 = 10 μm. Further, the optical elements 15 are lenses having a distance Pr2 of about 44 μm between adjacent optical elements 15 and a radius of curvature of about 0.2 mm, and are regularly arranged so as not to have a flat portion. The haze values of the optical films 6 and 6a are about 20.2 and about 1.9, respectively.

  As shown in FIG. 31, it can be seen that the angular distribution of the emitted light from the surface light source device hardly changes depending on the presence or absence of the protrusion 5 and the optical element 15. In the optical film 6 having the optical element 15, since the emitted light is diffused, the peak luminance is reduced by about 5%.

  Next, partial adhesion and iridescent coloring are evaluated by the surface light source device shown in FIG. The rainbow color coloring by the optical film 6 is evaluated by visual observation with the light source 10 turned on in the configuration shown in FIG. The partial adhesion between the optical film 6 and the diffusion film 8 is evaluated by rubbing while pressing the diffusion film 8 from above with a cotton swab in a state where the light source 10 is not lit and in a state where the light source 10 is lit. When the optical film 6 and the diffusing film 8 are in close contact with each other at the rubbed portion, the portion is visually darkened or colored, and luminance unevenness with the unrubbed portion can be confirmed.

  In FIG. 32, the result of having evaluated the partial adhesion of the optical film 6 and the diffusion film 8, and iridescent coloring is shown. The results using the optical film 6a are also shown in FIG. In the table of FIG. 32, ◯ indicates that partial adhesion or iridescent coloring is eliminated, and x indicates that partial adhesion or iridescent coloring is not eliminated. As shown in FIG. 32, it can be seen that the partial adhesion is particularly eliminated when the height of the protrusion 5 is in the range of 9.3 μm to 10.2 μm. Further, the rainbow color cannot be eliminated with the optical film 6a having no optical element 15 and having the optical film 6a having the haze value of about 1.9 and the optical element 15 having the haze value of about 9.4. In the optical film 6 having the optical element 15 and having a haze value of about 20.2, iridescent coloring is eliminated.

  Next, the manufacturing method of the optical film 6 used for the surface light source device which concerns on embodiment is demonstrated using FIG.33 and FIG.34. The protrusion 5, the optical element 15, and the deflection element 3 are transferred by a transfer process using transfer molds 60a and 60b. In the mold 60a, depressions corresponding to the protrusions 5 and the optical elements 15 are formed on the surface of a cylindrical metal subjected to copper plating or the like by etching or the like. In the case of copper plating, in order to prevent rusting, a surface protective layer is formed by chromium plating or the like after forming a recess. The mold 60b forms a groove corresponding to the shape of the deflection element 3 by cutting with a cutting tool on a cylindrical metal surface subjected to nickel plating or the like. Alternatively, a groove corresponding to the shape of the deflecting element 3 may be formed by etching or the like. Further, the ridge line direction of the groove formed in the mold 60b may be a circumferential direction or a longitudinal direction of the mold 60b, or may be a direction inclined by a predetermined angle from these directions.

  The base film 1 may be a PET film, for example, Toyobo Co., Ltd., trade name Cosmo Shine, product number A4300, and thickness 50 μm. In addition, a transparent film, particularly a film that transmits UV rays well, can be used.

  As shown in FIG. 33, a roller 61a is installed in the film supply unit of the optical film forming apparatus, a mold 60a is installed in the transfer unit, and a roller 61b is installed in the film winding unit. A photocurable resin 63 is dropped from the dispenser 62 onto the surface of the base film 1 supplied from the roller 61a. While the projection 5 and the optical element 15 are formed on the photocurable resin 63 on the base film 1 by the mold 60a, the photocurable resin 63 is cured by irradiating the photoirradiating device 64 with ultraviolet rays or the like. The protrusion layer 4 is pressure-bonded together. The base film 1 released from the mold 60a is wound around the roller 61b.

  As shown in FIG. 34, a roller 61b is installed in the film supply unit of the optical film forming apparatus, a mold 60b is installed in the transfer unit, and a roller 61c is installed in the film winding unit. The photocurable resin 63 is dropped from the dispenser 62 onto the surface of the base film 1 supplied from the roller 61b where the protruding layer 4 is not pressure-bonded. While the deflecting element 3 is formed on the photocurable resin 63 on the base film 1 by the mold 60 b, the photocurable resin 63 is cured by irradiating the photocurable resin 63 by irradiating ultraviolet rays or the like with the light irradiation device 64. Layer 2 is crimped together. The base film 1 released from the mold 60b is wound around the roller 61c. In this way, the optical film 6 is manufactured.

  In the optical film 6 according to the embodiment, the deflecting element layer 2 and the protruding layer 4 are formed using a photocurable resin 63 having good shape transferability. Therefore, as shown in FIG. 35, the transferred deflection element 3 can be formed with a sharp tip. For example, the height of the deflecting element 3 can be shifted by 0.2 μm or less of the design value. Moreover, since the PET film with high strength is used for the base film 1, the strength of the optical film 6 can be ensured.

  In the above description, the deflection element layer 2 is molded after the projection layer 4 is molded, but the molding order is not limited. The protrusion layer 4 may be formed after the deflection element layer 2 is formed first.

  Further, in the transfer process of transferring the protrusion 5 and the optical element 15 or the deflecting element 3 to the photocurable resin 63, the photocurable resin 63 may be difficult to release from the mold 60a or the mold 60b. When the photocurable resin 63 is not released from the mold 60a or the mold 60b, a defect is generated in the optical film 6, resulting in a defective product. In order to prevent this problem, when a mold release process is performed on the mold 60a and the mold 60b using a mold release agent (for example, manufactured by Daikin Chemicals Sales Co., Ltd., product name Durasurf, product number HD-2101Z). Good. The mold release treatment can improve the mold releasability of the photocurable resin 63 from the mold 60a and the mold 60b, and prevents the photocurable resin 63 from remaining on the mold 60a and the mold 60b. Can do. As a result, defects in the optical film 6 are less likely to occur.

  Next, a method for producing the photocurable resin 63 will be described. As the photocurable resin 63, a urethane acrylate type photocurable resin will be described as an example.

  A stirrer, thermometer, cooling pipe and air gas introduction pipe are attached to a 2 L three-necked flask. After introducing air gas into the three-necked flask, polytetramethylene glycol (Hodogaya Chemical Co., Ltd., trade name: PTG850SN) 520.80 g, diethylene glycol 1.06 g, unsaturated fatty acid hydroxyalkylene ester modified ε-caprolactone (Daicel Chemical Industries) 275.20 g manufactured by Co., Ltd., trade name: FA2D), 0.5 g of p-methoxyquinone as a polymerization inhibitor, and 0.3 g of dibutylthitin dilaurate (trade name: L101, manufactured by Tokyo Fine Chemical Co., Ltd.) as a catalyst, 70 ° C. The temperature rises to After the temperature rise, while stirring at 70 ° C. to 75 ° C., 222 g of isophorone diisocyanate (manufactured by Sumika Bayer Urethane Co., Ltd., trade name: Desmodur I) is uniformly dropped over 2 hours to carry out the reaction. After completion of the dropwise addition, the reaction is carried out for about 5 hours to perform IR measurement. As a result of IR measurement, it is confirmed that the isocyanate has disappeared, and the reaction is terminated, and a urethane oligomer having a weight average molecular weight of 7,000 is obtained.

  The urethane oligomer and 1,9-nonanediol diacrylate (manufactured by Kyoeisha Chemical Co., Ltd.) are mixed at a ratio of 3: 7 to 5: 5 to prepare the photocurable resin 63. In addition to the above components, 1 part by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by Ciba Specialty Chemicals, trade name: Irgacure 184) is included as a photoinitiator.

(Other embodiments)
As mentioned above, although this invention was described by embodiment of this invention, it should not be understood that the statement and drawing which make a part of this indication limit this invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art. Accordingly, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

  The optical film and the surface light source device of the present invention can be used as a backlight in liquid crystal display devices such as mobile phones, game machines, electronic notebooks, car navigation systems, notebook PCs, and TVs.

DESCRIPTION OF SYMBOLS 1 ... Base film 2 ... Deflection element layer 3 ... Deflection element 3a ... 1st inclined surface 3b ... 2nd inclined surface 4 ... Projection layer 5 ... Projection 6 ... Optical film 7 ... Light guide plate 8 ... Diffusion film 9 ... Reflector 10 ... Light source DESCRIPTION OF SYMBOLS 11 ... Incident surface 12 ... Outgoing surface 13 ... Reflecting surface 14 ... Reflecting element 15 ... Optical element

Claims (19)

A translucent base film having first and second main surfaces facing each other;
A deflecting element layer having a plurality of deflecting elements disposed in the first main surface and extending in one direction adjacent to each other;
A protrusion layer disposed on the second main surface and having a plurality of protrusions and a plurality of optical elements;
Each of the plurality of optical elements has a height in the range of 0.01 μm to 2 μm and a distance between adjacent optical elements in the range of 3 μm to 100 μm,
Each of the plurality of protrusions has a height in the range of 3 to 30 μm, a width at a half position of the height in a range of 1 to 60 μm, and a distance between adjacent protrusions in a range of 50 to 3000 μm. An optical film characterized by the above.   The optical film according to claim 1, wherein the protrusion layer has a haze value of 10 to 80.   3. The optical film according to claim 1, wherein each of the plurality of optical elements is a lens having a curvature radius in a range of 0.1 mm to 0.3 mm.   4. The optical film according to claim 1, wherein each of the plurality of optical elements includes a plurality of lenses having different curvature radii.   5. The optical device according to claim 1, wherein the plurality of optical elements are spread on the surface of the projection layer excluding a portion where the plurality of projections are arranged without gaps. the film.   The optical film according to claim 1, wherein the plurality of optical elements are arranged at equal intervals.   3. The lens according to claim 1, wherein each of the plurality of optical elements is a lens having a length in a direction orthogonal to the stretching direction compared to a length of the plurality of deflecting elements in a stretching direction. Optical film.   The optical film according to claim 1, wherein the plurality of optical elements are arranged in a lattice pattern.   The optical film according to claim 1, wherein each of the plurality of optical elements has a hexagonal planar shape. The plurality of deflection elements are arranged at regular intervals with a period of 3.5 to 30 μm,
Each of the plurality of deflection elements is a triangle having a first and second inclined surfaces in a cross section cut in a direction orthogonal to the extending direction of the plurality of deflection elements, and the first and second inclined surfaces are the first The optical film according to any one of claims 1 to 9, wherein the angle formed with the normal line of the main surface is in the range of 6 to 16 ° and in the range of 30 to 40 °, respectively. The plurality of deflection elements are arranged at equal intervals in a cycle of 4.9 to 10.1 μm,
The angles formed by the first and second inclined surfaces and the normal line of the first main surface are in the range of 8-12 ° and in the range of 34-38 °, respectively.
Each of the plurality of protrusions has a height in a range of 7 to 13 μm, a width in a half position of the height in a range of 6 to 20 μm, and a distance between adjacent protrusions in a range of 250 to 350 μm. The optical film according to any one of claims 1 to 9, wherein: The plurality of deflection elements are arranged at equal intervals in a cycle of 4.9 to 5.1 μm,
The angles formed by the first and second inclined surfaces and the normal line of the first main surface are in the range of 9.8 to 10.8 ° and in the range of 35.5 to 36.5 °, respectively.
Each of the plurality of protrusions has a height in the range of 9 to 12 μm, a width in the half position of the height in the range of 10 to 17 μm, and a distance between adjacent protrusions in the range of 285 to 295 μm. The optical film according to any one of claims 1 to 9, wherein: Each of the plurality of deflection elements has a sawtooth shape in which the lengths of two sides sandwiching the tip of the tooth are different by 10% or more and the depression angle is 60 ° or less, and the refractive index of the plurality of deflection elements is n, average When the period is d, the average depth h of the sawtooth grooves is h = α × d / (n−1) (where 0.4 ≦ α ≦ 1.0), and 0.46 μm ≦ λ1 ≦ 0.50 μm, 0.53 μm ≦ λ2 ≦ 0.57 μm, 0.60 μm ≦ λ3 ≦ 0.64 μm, and light of three wavelengths λ1, λ2, and λ3 within an angle range of 15 degrees ≦ γ1 ≦ 70 degrees The diffraction angle that maximizes the diffraction efficiency of each wavelength λ1, λ2, and λ3 is included in the range of −5 degrees to +5 degrees when
Each of the plurality of protrusions has a height in the range of 9 to 12 μm, a width in the half position of the height in the range of 10 to 17 μm, and a distance between adjacent protrusions in the range of 285 to 295 μm. The optical film according to any one of claims 1 to 9, wherein: Each of the plurality of deflecting elements is composed of grooves or peaks having an average period of 200 μm or less constituting a hologram, and the hologram bends white light having an incident angle of 30 ° ± 15 ° in a direction perpendicular to the projection layer, A sawtooth shape in which the refractive index of the optical material is n, the average period is 5.0 ± 1.0 μm, and the average depth is (3.7 ± 1.0) / (n−1) μm, or The groove is filled with less than 50% of the depth, and the average period d and the positional deviation u of the sawtooth crest are in the range of u / d ≦ 0.2,
Each of the plurality of protrusions has a height in the range of 9 to 12 μm, a width in the half position of the height in the range of 10 to 17 μm, and a distance between adjacent protrusions in the range of 285 to 295 μm. The optical film according to any one of claims 1 to 9, wherein:   The optical film according to claim 1, wherein the plurality of protrusions are regularly arranged.   The optical film according to claim 15, wherein the protrusions are arranged in a unit lattice having a square unit cell.   The optical film according to claim 15 or 16, wherein the direction of the arrangement of the protrusions is parallel to the extending direction of the plurality of deflection elements.   The optical film according to claim 1, wherein the deflection element layer and the protruding layer are a photocurable resin. A light source;
An end surface facing the light source is an incident surface, and each of a pair of main surfaces orthogonal to the incident surface is a reflective surface and an output surface. The light incident on the light source through the incident surface is disposed on the reflective surface. A light guide plate having a reflective element that reflects toward the surface;
The optical film according to any one of claims 1 to 18, which is disposed so as to face the emission surface,
A diffusion film facing the emission surface across the optical film;
A surface light source device, comprising: a reflector disposed opposite to the reflection surface and configured to make light emitted from the reflection surface enter the light guide plate.