Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/29—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the position or the direction of light beams, i.e. deflection
  • G02F1/295—Analog deflection from or in an optical waveguide structure]
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
  • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
  • G02B6/0033—Means for improving the coupling-out of light from the light guide
  • G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it
  • G02B6/0038—Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
  • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
  • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
  • G02B6/0015—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it
  • G02B6/0016—Grooves, prisms, gratings, scattering particles or rough surfaces
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
  • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
  • G02B6/0033—Means for improving the coupling-out of light from the light guide
  • G02B6/005—Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
  • G02B6/0053—Prismatic sheet or layer; Brightness enhancement element, sheet or layer

Definitions

• Light guide for surface light source device method of manufacturing the same, and surface light source device
• the present invention relates to an edge light type surface light source device, a light guide used therefor, and a method of manufacturing the same, and more particularly to a surface light source device intended to reduce the visibility of uneven brightness and a light guide used therefor. It is about the body.
• the surface light source device of the present invention is used, for example, as a backlight of a liquid crystal display device used as a monitor of a portable notebook personal computer or a display unit of a liquid crystal television or a video integrated liquid crystal television, or a portable telephone such as a mobile phone.
• Backlight of a relatively small liquid crystal display device used as a display panel of a portable electronic device or an indicator of various devices or a backlight of a liquid crystal display device used as a signboard or signboard at a station or a public facility. It is suitable for a backlight of a liquid crystal display device used as a marking device for a traffic sign or the like on an expressway or a general road.
• Liquid crystal display devices have been widely used as monitors for portable notebook personal computers and the like, or as display units for liquid crystal televisions and video-integrated liquid crystal televisions, and in various other fields.
• a liquid crystal display device basically includes a backlight and a liquid crystal display element.
• an edge light type is widely used from the viewpoint of downsizing the liquid crystal display device.
• an edge-light type backlight at least one end face of a rectangular plate-shaped light guide is used as a light incidence end face, and a linear or rod-shaped light source such as a straight tube fluorescent lamp is arranged along the light incidence end face.
• a primary light source is disposed, light emitted from the primary light source is introduced into the light guide from the light incident end face of the light guide, and a light emitting surface that is one of two main surfaces of the light guide is provided. What emits light from is widely used.
• the surface light source device is also required to be thinner, and in order to meet this demand, it is necessary to make the light guide thinner.
• part of the light incident on the light incident end face of the light guide from the primary light source is incident on the light emitting surface or the back surface at an incident angle equal to or greater than the critical angle for total reflection.
• the light is guided by total internal reflection, another part is incident on the light exit surface at an angle smaller than the critical angle for total reflection, and a part of the light exits from the light exit surface.
• the light guide becomes thinner (for example, about 0.5 mm and 3 mm in thickness), when light emitted from the primary light source exits in the region near the light incident end face of the light exit surface of the light guide, Periodically, a high-luminance part (bright line or bright band) and a low-luminance part (dark line or blue band) appear with respect to the distance from the light incident surface.
• This phenomenon is not particularly problematic in practice when the frame width is large.However, in the case of the above-described surface light source device having a small frame width, uneven brightness due to this effect is particularly evident. Become.
• Patent Document 1 discloses a method in which a light incident end face is parallel to a light emitting face. It is disclosed that the arithmetic average roughness Ra in any direction is 0.05-0.3 / im.
• Patent Document 1 discloses a method in which a light incident end face is parallel to a light emitting face. It is disclosed that the arithmetic average roughness Ra in any direction is 0.05-0.3 / im.
• the arithmetic mean roughness Ra of the light incident end face is set to 0.05-0.3 / m, and the force of the light guide is determined by the roughness of the light guide in the thickness direction. It is disclosed that the degree of roughness in the direction parallel to the light emitting surface is made rougher than the degree. Also, for example, in Japanese Patent Application Laid-Open No. 2002-324424 (Patent Document 3), the maximum height Ry of the light incident end face is 3-5 / m, and the average roughness Ra is 0.3 or more and 0.6 or less. It is disclosed that the light incident end face has, for example, a matte surface. Further, for example, Japanese Patent Application Laid-Open No. 2000-306410 (Patent Document 4) discloses that a prism having an apex angle of 160 to 175 degrees is formed on a light incident end surface along a direction parallel to a light exit surface. Being done.
• Patent Document 1 Japanese Patent Application Laid-Open No. Hei 9-1160035 [Patent No. 3253001]
• Patent Document 2 JP 2001-83512 A
• Patent Document 3 Japanese Patent Application Laid-Open No. 2002-324424
• Patent Document 4 JP 2000-306410 A Disclosure of the invention
• the light emitted from the primary light source functions as a secondary light source at the light guide ridge that forms the boundary between the light incident end face and the light exit face of the light guide.
• Intense light is emitted from the light-emitting surface of the surface light source device in an oblique direction that is inclined to the normal line direction, degrading the quality of the displayed image when used as a backlight for liquid crystal display devices. May be.
• Patent Documents 114 cannot sufficiently suppress such a phenomenon.
• the present invention provides a surface light source device that has a small amount of specific light emission in the oblique direction near the light incident end face where brightness unevenness near the light incident end face of the light guide due to the thinning of the light guide is difficult to see. It is an object of the present invention to provide a light guide for use with the light guide.
• a light guide for a surface light source device which is used to form a surface light source device in combination with a primary light source and guides light emitted from the primary light source
• the light incident end face has an average inclination angle in the thickness direction of the light guide obtained based on the measurement with an ultra-depth shape measurement microscope of 3 ° or more and 12 ° or less, wherein the light guide for a surface light source device is provided.
• Body
• the light incident end face has a component having an inclination angle of 20 ° or more in the frequency distribution of the inclination angle obtained based on the measurement by the ultra-depth shape measuring microscope, and the proportion of the component having an inclination angle of 20 ° or more is 40% or less.
• the light incident end face is a center line average in a thickness direction of the light guide obtained based on measurement by an ultra-depth shape measuring microscope.
• the roughness Ra is not less than 0.2 / 1 111 and not more than 0.4 / im.
• the light incident end face has a ten-point average roughness Rz in the thickness direction of the light guide obtained by measurement with an ultra-depth shape measuring microscope of 0.7 ⁇ or more 2.0. ⁇ or less.
• the light incident end surface includes a rough surface, a plurality of lens arrays extending in parallel to each other in a direction orthogonal to a thickness direction of the light guide, and a cross-sectional shape of the lens array. Or a plurality of lens arrays extending parallel to each other in a direction perpendicular to the thickness direction of the light guide, and roughening at least a part of the lens arrays. This is a lens row forming surface.
• the primary light source is disposed so as to face the light incident end face of the light guide for a surface light source device as described above.
• the above-described surface light source device is provided.
• the surface light source device is arranged on a light exit surface of the light guide, and receives light emitted from the light exit surface of the light guide. And a light deflecting element having a light exit surface on the opposite side.
• the light deflecting element includes a plurality of prism rows extending on a light incident surface along a light incident end face of the light guide and arranged in parallel with each other. Each has a first prism surface on which light from the light exit surface of the light guide enters, and a second prism surface on which the incident light is internally reflected.
• the primary light source is a linear light source or a point light source.
• a method for manufacturing a light guide for a surface light source device as described above, wherein a transparent synthetic resin is molded A surface light source, wherein the light emitting surface, the back surface, and the light incident end surface are formed by transferring the shape of the surface of the mold member by molding using a member, thereby obtaining the light guide for the surface light source device.
• the light incident end face of the light guide for a surface light source device has an average inclination angle of 3 ° or more in the thickness direction of the light guide obtained based on the measurement by the ultra-depth shape measuring microscope.
• the angle By setting the angle to be equal to or less than 12 °, in the surface light source device, uneven brightness in the area near the light incident end face due to the thinning of the light guide becomes difficult to be recognized, and the oblique light near the light incident end face is reduced. Directive specific light emission can be reduced.
• the resonance of the target light emission can be made sufficient.
• FIG. 1 is a schematic perspective view showing one embodiment of the surface light source device according to the present invention
• FIG. 2 is a partial sectional view thereof.
• the surface light source device of the present embodiment has a light guide 3 in which at least one side end surface is a light incident end surface 31 and one surface substantially orthogonal to this is a light exit surface 33.
• a linear primary light source 1 disposed opposite the light incident end face 31 of the light guide 3 and covered with the light source reflector 2; and a light deflecting element 4 disposed on the light exit surface of the light guide 3
• a light reflection element 5 disposed opposite to a back surface 34 of the light guide 3 opposite to the light exit surface 33.
• the light guide 3 is arranged parallel to the XY plane, and has a rectangular plate shape as a whole.
• the light guide 3 has four side end faces, and at least one of the pair of side end faces parallel to the YZ plane is a light incident end face 31.
• the light incident end face 31 is arranged so as to face the primary light source 1, and light emitted from the primary light source 1 enters the light guide 3 from the light incident end face 31.
• the light source may be disposed so as to face another side end face such as the side end face 32 opposite to the light incident end face 31.
• the two main surfaces of the light guide 3 that are substantially perpendicular to the light incident end surface 31 are respectively located substantially parallel to the XY plane, and one of the surfaces (the upper surface in the figure) is the light exit surface 33.
• one of the surfaces is the light exit surface 33.
• a directional light emitting mechanism having a rough surface to at least one of the light emitting surface 33 and the rear surface 34 thereof, light incident from the light incident end surface 31 is guided through the light guide 3.
• light with directivity is emitted from the light exit surface 33 to a plane (XZ plane) orthogonal to the light incident end surface 31 and the light exit surface 33.
• the direction of the peak (peak light) of the luminous intensity distribution in the XZ plane distribution forms an angle with the light exit surface 33.
• the angle is, for example, 10 to 40 degrees, and the full width at half maximum of the luminous intensity distribution of the emitted light is, for example, 10 to 40 degrees.
• the rough surface or the lens array that is formed on the main surface of the light guide 3 and that constitutes the directional light emission mechanism may have an average inclination angle ⁇ a 'in the range of 0.5 to 15 degrees. It is preferable from the viewpoint of improving the uniformity of luminance in the light emitting surface.
• the average inclination angle ⁇ a ' is more preferably in the range of 11 to 12 degrees, and more preferably in the range of 1.511 degrees. The method for measuring the average inclination angle will be described later.
• the other main surface to which the directional light emission mechanism is not provided is used to control the directivity of light emitted from the light guide 3 on a plane (YZ plane) parallel to the primary light source 1.
• a lens array forming surface on which a number of lens arrays extending in a direction (X direction) substantially perpendicular to the light incident end face 31 are arranged.
• a rough surface is formed on the light exit surface 33, and a lens array composed of an array of a number of lens arrays extending substantially perpendicularly (X direction) to the light incident end surface 31 on the rear surface 34.
• a lens array forming surface may be formed on the light emitting surface 33 and the rear surface 34 may be roughened.
• the lens array when a lens array forming surface for controlling the directivity on the YZ plane is formed on the back surface 34 or the light emitting surface 33 of the light guide 3, the lens array is substantially It is preferable to use a prism row having a substantially triangular cross section in a force S, YZ section, such as a prism row extending in the X direction, a lenticular lens row, and a V-shaped groove.
• the apex angle is preferably in the range of 85 to 110 degrees. This is because by setting the apex angle in this range, the light emitted from the light guide 3 can be appropriately collected. This is because the luminance of the surface light source device can be improved, and the range is more preferably 90 to 100 degrees.
• a desired prism array shape is accurately produced, stable optical performance is obtained, and abrasion and deformation of the prism top during assembly work or use as a light source device are prevented.
• a flat portion or a curved surface portion may be formed at the top of the prism row.
• the light incident end face 31 has an average inclination angle ⁇ a in the thickness direction of the light guide 3 of 3 ° or more and 12 ° or less.
• the average inclination angle ⁇ a is less than 3 °, the amount of light emitted from the area near the light guide light incident end face decreases, and the luminance in this area becomes too low.On the other hand, the average inclination angle ⁇ a is 12 °. If it exceeds, the light output in the area near the light guide light incident end face increases and the luminance in this area becomes too high, and the specific light emission in the oblique direction near the light incident end face can be reduced. It becomes hard.
• the average inclination angle ⁇ a of the light incident end face 31 in the thickness direction of the light guide 3 is preferably 5 ° or more and 11 ° or less, more preferably 6 ° or more and 9 ° or less.
• the average tilt angle ⁇ a can be obtained from a tilt angle force measured using an ultra-depth shape measuring microscope (for example, VK-8500 [trade name] manufactured by KEYENCE CORPORATION). That is, the average inclination angle is determined by measuring the center line average roughness Ra and the ten-point average roughness Rz of the surface such as the light incident end face of the light guide 3 using an ultra-deep shape measurement microscope, and Ra and Rz are read, and a cross-sectional curve is extracted from this measurement range under the condition of smoothing 02.
• an ultra-depth shape measuring microscope for example, VK-8500 [trade name] manufactured by KEYENCE CORPORATION
• Each measurement point (the range that can be measured at one time under these measurement conditions is about 110 ⁇ m, so the light guide The absolute value of the inclination angle in the area excluding 50 zm at both ends in the thickness direction of the light guide on the end face is measured at equal intervals), and by averaging these, the force S can be obtained. [0028] Along with the above-described average tilt angle ⁇ a, the frequency distribution of the tilt angle at the measurement point also affects the light emission characteristics of the surface light source device.
• the occurrence of specific light emission in the oblique direction in the vicinity of the light incident end face mainly includes components with a tilt angle of 20 ° or more in the frequency distribution of the tilt angle obtained based on the measurement by the above-mentioned ultra-depth shape measurement microscope.
• the ratio is affected. It is preferable that this abundance ratio be 40% or less in order to reduce the specific light emission in the oblique direction near the light incident end face of the surface light source device.
• the proportion of the component having a tilt angle of 20 ° or more in the frequency distribution of the tilt angle obtained based on the measurement by the ultra-depth shape measuring microscope is more preferably 30% or less, and further preferably 20% or less.
• the light incident end face 31 as described above is made of, for example, a rough surface.
• the method of forming a rough surface include a method of cutting with a rice tool or the like, a method of polishing with a grindstone, sandpaper, puff, or the like, a method of blasting, electric discharge machining, electrolytic polishing, or chemical polishing.
• the blast particles used for blasting include spherical particles such as glass beads and polygonal particles such as alumina beads. The use of polygonal particles is more effective in spreading light. It is preferred because it can form a surface. By adjusting the processing direction of cutting or polishing, an anisotropic rough surface can be formed.
• the processing direction in the Z direction can be adopted to form a zigzag streaky uneven shape, and the adjustment of the spread of light in the XZ plane can be performed.
• the processing direction in the Y direction can be adopted to form a streaky uneven shape in the Y direction.
• a rough surface having no directivity can be formed. This rough surface calorie can be applied directly to the light incident end face of the light guide, but the light incident end face transfer of the mold member in a mold apparatus for molding a light transmitting synthetic resin into the light guide using a mold member.
• a corresponding transfer forming surface may be formed on the surface for forming, and this may be transferred to a light-transmitting synthetic resin at the time of molding.
• the light incident end face 31 is provided with a plurality of lens rows extending parallel to each other in a direction (Y direction) orthogonal to the thickness direction (Z direction) of the light guide. And a lens row forming surface.
• a prism array can be used as the lens array.
• This lens array preferably includes a curve in the XZ cross-sectional shape from the viewpoint of the light diffusion effect.
• Fig. 3 shows a schematic cross-sectional shape of the light incident end face where such a lens array is formed.
• the lens surface 31a is a curved surface that is outwardly convex with a radius of curvature R, and has a maximum distance d with respect to a triangular prism shape having a vertex angle ⁇ and a pitch P.
• a method for forming the lens array forming surface on the light incident end face a method of cutting with a milling tool or the like is preferable.
• the processing of the lens array forming surface can be performed directly on the light incident end face of the light guide, but the light of the mold member is used in a mold apparatus for molding a light-transmitting synthetic resin into the light guide using the mold member.
• a corresponding transfer forming surface may be formed on the surface for transfer formation of the incident end surface, and this may be transferred to a light-transmitting synthetic resin during molding.
• the light incident end face 31 is a lens row forming surface including a plurality of lens rows extending parallel to each other in a direction (Y direction) orthogonal to the thickness direction (Z direction) of the light guide.
• the surface roughening lens row forming surface may be roughened by sanding, puffing, or the like, blasting, electrolytic polishing, chemical polishing, or the like. These roughened surfaces can be applied directly to the light incident end face of the light guide where the lens rows are formed.
• a corresponding transfer forming surface may be formed on the surface of the mold member for light incident end surface transfer forming, and this may be performed by transferring it to a transparent synthetic resin at the time of molding.
• a light guide is formed by transferring the shape of the surface of the mold by molding a light-transmitting synthetic resin using the mold. Obtain a light-guiding material corresponding to. Thereby, the surface of the light guide material corresponding to the light exit surface and the back surface of the light guide is formed to be equal to the light exit surface and the back surface. Next, the light incident end face is formed by cutting the surface of the light guide material corresponding to the light incident end face of the light guide to obtain the light guide for the surface light source device.
• a light-transmitting synthetic resin is molded using a mold member to transfer the shape of the surface of the mold member to a light-emitting surface, a back surface, and a light-emitting surface.
• the light guide for the surface light source device is obtained by forming the incident end face.
• the light incident end face 31 may have a centerline average roughness Ra in the thickness direction of the light guide obtained based on the measurement by the ultra-depth shape measuring microscope of not less than 0.4 and not more than 0.4 ⁇ m.
• the light guide has a ten-point average roughness Rz in the thickness direction of not less than 0. 2. and not more than 2. O xm, which is obtained based on measurement with a super-depth shape measuring microscope.
• Rz ten-point average roughness
• the surface properties of the light incident end face 31 are such that the average inclination angle ⁇ a is 113 degrees in the longitudinal direction, that is, the direction (Y direction) orthogonal to the light guide thickness direction (Z direction), and the center line.
• the average roughness Ra is 0.02 to 0.1 lzm
• the ten-point average roughness Rz is 0.3 to 2 zm.
• the average inclination angle ⁇ a is more preferably 1.3 to 2.7 degrees, and particularly preferably 1.5 to 2.5 degrees.
• the center line average roughness Ra is more preferably in the range of 0.03-0.08 x m, and particularly preferably in the range of 0.05-1.07 z m.
• the ten-point average roughness Rz is more preferably in the range of 0.4 to 1.7 ⁇ m, particularly preferably in the range of 0.5 to 1.5 x m.
• the light guide 3 is not limited to the shape as shown in FIG. 1, but may have various shapes such as a light incident end face having a thicker or wedge shape.
• the light deflection element 4 is arranged on the light exit surface 33 of the light guide 3.
• the two main surfaces 41 and 42 of the light deflecting element 4 are arranged as a whole in parallel with each other, and are respectively positioned as a whole in parallel with the XY plane.
• One of the principal surfaces 41 and 42 (the principal surface located on the light exit surface 33 side of the light guide 3) is a light entrance surface 41, and the other is a light exit surface 42.
• the light exit surface 42 is a flat surface parallel to the light exit surface 33 of the light guide 3.
• the light incident surface 41 is a prism array forming surface on which a number of prism arrays extending in the Y direction are arranged in parallel with each other.
• the prism array forming surface may have a relatively flat bottom flat portion between adjacent prism arrays (for example, a flat portion having a width approximately equal to or smaller than the X dimension of the prism array). From the viewpoint of increasing the utilization efficiency of the prism, it is preferable to arrange the prism rows continuously in the X direction without providing a flat bottom portion.
• FIG. 4 schematically shows how light is deflected by the light deflector 4.
• This figure shows an example of the traveling direction of the peak light (light corresponding to the peak of the emitted light distribution) from the light guide 3 in the XZ plane.
• the peak light emitted obliquely from the light exit surface 33 of the light guide 3 at an angle is incident on the first prism surface of the prism array, is totally internally reflected by the second prism surface, and is substantially reflected by the light exit surface 42. Emit in the direction of the line.
• the brightness in the direction of the normal to the light exit surface 42 can be sufficiently improved in a wide range by the action of the prism array on the light guide back surface 34 as described above.
• FIG. 5 schematically shows light emission from a light guide light emitting surface, particularly a region near the light incident end face, for reference.
• FIG. 6 schematically shows light emission from the light deflecting element light emitting surface of the surface light source device, particularly from a region near the light guide light incident end face, for reference.
• the peak light of the light entering from 31 exits from the light exit surface 33 at an angle, enters the light deflecting element 4 from one prism surface, is internally reflected by the other prism surface, and has a normal light exit surface. Emits in the direction.
• the peak light exits at an angle j3 with respect to the light exit surface 33 and enters the light deflector 4 from one prism surface. Then, according to the angle of / 3, the light is emitted at an angle ⁇ with respect to a light exit surface which receives or does not receive the internal reflection on the other prism surface of the light deflecting element 4.
• the angle ⁇ is affected by the surface properties of the light incident end face 31 of the light guide, and is immediately affected by the average inclination angle ⁇ a in the plane and the distribution of the number of inclination angles.
• the proportion of the component having a tilt angle of 20 ° or more in the frequency distribution of the tilt angle is excessively large, the light incident on the light deflecting element 4 has only the refraction function without being subjected to the internal reflection of the prism surface.
• the component that emits light upon receiving the light becomes too large, and the specific light emission in the oblique direction in the region near the light incident end face becomes conspicuous.
• a range of the average inclination angle ⁇ a that achieves a light emission state equal to or close to the central part in the region near the light incident end face, and further, an inclination angle of 20 ° in the frequency distribution of the inclination angle is defined as the above-mentioned specific range. The degree of uniformity is maintained, and the occurrence of specific light emission in the oblique direction in the region near the light incident end face is suppressed.
• a desired prism shape is precisely manufactured to obtain stable optical performance, and at the same time, abrasion and deformation of the prism top during assembly work or when used as a light source device are prevented.
• a flat top portion or a top curved surface portion may be formed at the top of the prism array.
• the width of the flat top portion or the curved top portion should be 3 zm or less. This is preferable from the viewpoint of reducing the luminance of the power source light source device and suppressing the occurrence of a non-uniform luminance pattern due to the sticking phenomenon. More preferably, the width of the flat top portion or the curved top portion is 2 ⁇ m or less, more preferably 1 ⁇ m or less.
• the primary light source 1 is a linear light source extending in the Y direction.
• a fluorescent lamp or a cold cathode tube can be used.
• the primary light source 1 should not only be installed facing one side end face of the light guide 3, but also installed on the opposite side end face if necessary. You can also.
• a point light source such as a light emitting diode (LED) can be used.
• a light source in which a plurality of point light sources are arranged at appropriate intervals can be used.
• the light source reflector 2 guides the light of the primary light source 1 to the light guide 3 with little loss.
• a plastic film having a metal deposition reflective layer on the surface can be used.
• the light source reflector 2 avoids the light deflecting element 4 and passes from the outer surface of the edge of the light reflecting element 5 through the outer surface of the primary light source 1 to the edge of the light emitting surface of the light guide 3. It is wound.
• the light source reflector 2 can also be wound from the outer surface of the edge of the light reflecting element 5 to the outer surface of the primary light source 1 to the edge of the light emitting surface of the light deflecting element 4.
• Such a reflecting member similar to the light source reflector 2 can be attached to a side end surface of the light guide 3 other than the light incident end surface 31.
• the light reflection element 5 for example, a plastic sheet having a metal vapor deposition reflection layer on the surface can be used.
• a light reflection layer or the like formed on the back surface 34 of the light guide 3 by metal deposition or the like can be used.
• the light guide 3 and the light deflecting element 4 of the present invention are made of a synthetic resin having a high light transmittance.
• a synthetic resin examples include a methacrylic resin, an acrylic resin, a polycarbonate resin, a polyester resin, and a vinyl chloride resin.
• methacrylic resin is optimal because of its high light transmittance, heat resistance, mechanical properties, and moldability.
• a methacrylic resin is a resin containing methyl methacrylate as a main component, and preferably contains 80% by weight or more of methyl methacrylate.
• a transparent synthetic resin plate is formed using a mold member having a desired surface structure. It may be formed by hot pressing, or may be formed simultaneously with molding by screen printing, extrusion molding, injection molding or the like.
• the structure surface can be formed by using a heat or light curable resin.
• the surface of a transparent substrate such as a transparent film or sheet made of a polyester resin, an acrylic resin, a polycarbonate resin, a salt-based butyl resin, a polymethacrylimide resin, or the like is coated with an active energy ray-curable resin.
• a rough surface structure or a lens array arrangement structure may be formed, or such a sheet may be bonded and integrated on a separate transparent substrate by a method such as adhesion or fusion.
• the active energy ray-curable resin polyfunctional (meth) acrylic compounds, butyl compounds, (meth) acrylic esters, aryl compounds, metal salts of (meth) acrylic acid and the like can be used.
• a transmissive liquid crystal display element 8 as shown in FIG. 2 above, a liquid crystal display device using the surface light source device of the present invention as a backlight is constructed. The liquid crystal display device is observed by an observer from above in FIG.
• the light guide described in the embodiment of FIG. 14 and the surface light source device using the same were manufactured.
• One side end face (end face with a thickness of 2.2mm) corresponding to the side (long side) of 290mm in length of this light guide material was cut in a direction parallel to the main surface using a cutting machine. It was worked and roughened. As a result, the light incident end face is formed, and the light exit surface formed by the roughened main surface of the light guide material and the back surface formed by the prism row formed surface of the light guide material (the prism rows are perpendicular to the light incident end face). Extended). The surface roughness of the light incident end face of the obtained light guide was measured in the thickness direction of the light guide.
• an ultra-depth shape measuring microscope (VK-8500 [trade name] manufactured by KEYENCE CORPORATION) was used.
• VK-8500 [trade name] manufactured by KEYENCE CORPORATION
• the center line average roughness and the ten-point average roughness Rz of the light incident end face 31 of the light guide 3 in the light guide thickness direction were measured, and Ra and Rz within the measurement range were read.
• the objective lens used was 100x.
• the cross-sectional shape in the thickness direction of the light guide is extracted under the smoothing condition (simple average ⁇ 2), the absolute value of the tilt angle at each measurement point is obtained, and the average is obtained.
• a primary light source 1 composed of a cold cathode tube is arranged along the longitudinal direction of the light guide 3 so as to face the light incident end face 31 of the light guide 3, and a light source reflector 2 (silver manufactured by Reiko Co., Ltd.) (Reflective film).
• a light diffuse reflection film ( ⁇ 60 [trade name] manufactured by Toray Industries, Inc.) is attached to the other side end surface, and a light reflection / reflection sheet made of a light scattering / reflection sheet faces the back surface 34 of the light guide 3 where the prism array is formed.
• Element 5 was arranged.
• the above configuration was incorporated in a frame.
• This surface light source device The maximum peak of the emitted light luminous intensity distribution (in the XZ plane) was 70 degrees with respect to the normal direction of the light emitting surface, and the full width at half maximum was 22.5 degrees.
• one of the prism surfaces has a convex curved shape with a radius of curvature of 1000 zm, and the other prism surface has a planar shape.
• a prism sheet was formed by forming a prism array in which a large number of ⁇ m prism arrays were connected in parallel on one surface of a polyester film having a thickness of 125 ⁇ m.
• the light deflecting element 4 made of the obtained prism sheet is oriented such that the prism array forming surface faces the light exit surface (mat surface) 33 of the light guide 3, and the ridge of the prism array faces the light incident end surface 31 of the light guide 3. Are parallel to each other, and the flat prism faces of the respective prism rows are placed toward the light incident end face 31 of the light guide 3.
• LCD liquid crystal display element
• Example 1 was the same as Example 1 except that the finishing cutting speed was changed to a slightly lower speed when cutting by a cutting machine for roughening one side end surface corresponding to the long side of the light guide material. In the same manner, a surface light source device was obtained.
• the luminance of the region from the light guide light incident end face 33 to about 30 mm in the X direction was different from that of the other parts.
• no specific light emission in the oblique direction near the light guide light incident end face 33 was observed.
• Example 2 Same as in Example 1, except that the cutting speed for finishing by the cutting machine for roughening one side end surface corresponding to the long side of the light guide material was changed to a slightly higher speed. Thus, a surface light source device was obtained.
• the primary light source 1 was turned on, and the light emitting surface was visually observed.
• the brightness in the region from the light guide light incident end face 33 to about 30 mm in the X direction is almost the same as other parts, and the specific light in the oblique direction near the light guide light incident end face 33 The emission was hardly noticeable.
• Example 2 Same as in Example 1, except that the finishing cutting speed was changed to be very slow when cutting by a cutting machine to roughen one side end surface corresponding to the long side of the light guide material. To obtain a surface light source device.
• the luminance of the area from the light guide light incident end face 33 to about 30 mm in the X direction was the other part. A lower dark band was observed, and the luminance uniformity was low. Also, specific light emission in the oblique direction near the light guide light incident end face 33 was observed.
• Example 1 was the same as Example 1 except that the finishing cutting speed was changed to a very high speed when cutting by a cutting machine for roughening one side end surface corresponding to the long side of the light guide material. In the same manner, a surface light source device was obtained.
• the primary light source 1 When the primary light source 1 was turned on and the light emitting surface was visually observed with respect to the obtained surface light source device, the brightness of the area from the light guide light incident end face 33 to about 30 mm in the X direction was the other part. Higher and brighter bands were observed, and the luminance uniformity was lower.
• the neighborhood is dark
• the neighborhood is bright
• FIG. 1 is a schematic perspective view showing one embodiment of a surface light source device according to the present invention.
• FIG. 2 is a partial cross-sectional view of the surface light source device of FIG. 1.
• FIG. 3 is a partial cross-sectional view of a light guide.
• FIG. 4 is a schematic diagram showing a state of light deflection in a light deflection element.
• FIG. 5 is a schematic view showing a state of light emission with a regional force in the light guide light emitting surface, particularly in the vicinity of the light incident end face.
• FIG. 6 is a schematic view showing light emission from a light exit surface of a light deflecting element, particularly a region near a light guide light incident end face.

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• Physics & Mathematics (AREA)
• Nonlinear Science (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Mathematical Physics (AREA)
• Chemical & Material Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Planar Illumination Modules (AREA)
• Light Guides In General And Applications Therefor (AREA)
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• 2004
  • 2004-01-29 JP JP2004021604A patent/JP4553596B2/ja not_active Expired - Fee Related
• 2005
  • 2005-01-26 WO PCT/JP2005/001002 patent/WO2005073624A1/ja active Application Filing
  • 2005-01-26 KR KR1020067017370A patent/KR20060126797A/ko not_active Application Discontinuation
  • 2005-01-26 CN CN2005800033945A patent/CN1914460B/zh not_active Expired - Fee Related
  • 2005-01-26 KR KR1020087008021A patent/KR100927513B1/ko not_active IP Right Cessation
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