JP2014112487A - Light guide plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light guide plate with flexibility, a surface light source device and a transmissive image display device comprising the light guide plate, and a method of manufacturing the light guide plate.SOLUTION: According to one embodiment, a light guide plate 10 outputs light, as planar light, from a light output surface 11b intersecting a light input surface 11a, the light having been input from the light input surface 11a. The light guide plate 10 is provided with a light guide plate base material section 11, which has the light input surface 11a and the light output surface 11b, and which is formed of a transparent and flexible material.

Description

  The present invention relates to a light guide plate, a surface light source device, a transmissive image display device, and a method of manufacturing a light guide plate.

  A transmissive image display unit such as a liquid crystal panel does not emit light itself, but is illuminated by a separately provided surface light source device to display an image. An example of the surface light source device is, for example, a sidelight type surface light source device including a light guide plate and a light source unit disposed on the side of the light guide plate. A transmissive image display device including the transmissive image display unit and the surface light source device is widely known.

  In recent years, a flexible display device applied to electronic paper or the like has been demanded. For example, a self-luminous display device using organic EL is known (see Patent Document 1).

JP 2004-11879 A

  A flexible device is known as a self-luminous display device using organic EL. Recently, a flexible non-luminous display device employing a transmissive image display unit such as a liquid crystal panel is required. . In order to make a non-light emitting display device flexible, the light guide plate also needs to be flexible.

  Accordingly, an object of the present invention is to provide a flexible light guide plate, a surface light source device including the light guide plate, a transmissive image display device, and a method for manufacturing the light guide plate.

  A light guide plate according to one aspect of the present invention is a light guide plate that emits light incident from an incident surface as planar light from an output surface that intersects the incident surface. The light guide plate has an entrance surface and an exit surface, and includes a light guide plate base material portion made of a transparent and flexible material.

  Since the light guide plate base material portion is made of a transparent and flexible material, the light guide plate can have flexibility.

  In one embodiment, in the light guide plate base material portion, a plurality of light scattering portions that are provided on the back surface located on the opposite side of the light exit surface and scatter at least part of the light incident from the light entrance surface to the light exit surface side May be further provided.

In one embodiment, the material of the light guide plate base material portion may be a material in which the total light transmittance of the measurement base material portion made of the material is 80% or more. In this case, the base material part for measurement is a rectangular parallelepiped whose length in the longitudinal direction is 250 mm in the plan view shape. Further, the amount of light incident from the first side surface orthogonal to the longitudinal direction and emitted from the second side surface opposite to the first side surface is defined as Q _out, and the amount of light incident on the first side surface Is Q _in , the total light transmittance is defined as Q _out / Q _in .

  In one embodiment, when wound in a roll shape, the innermost radius may be flexible so as to be 2.5 cm or less.

  In one embodiment, the thickness of the light guide plate base material portion may be 0.7 mm or less.

  In one embodiment, in the light guide plate base material portion, a plurality of light scattering portions that are provided on the back surface located on the opposite side of the light exit surface and scatter at least part of the light incident from the light entrance surface to the light exit surface side Further, the light scattering portion may be a light scattering dot having a substantially circular shape in plan view. In this case, F / D may be 0.33 or less, where D is the thickness of the light guide plate base material portion and F is the diameter of the light scattering portion.

  Another aspect of the present invention relates to a surface light source device including the light guide plate according to the present invention and a light source that supplies light to an incident surface of the light guide plate.

  Still another aspect of the present invention provides a light guide plate according to the present invention, a light source that supplies light to an incident surface of the light guide plate, and a transmissive image display that displays an image by receiving planar light from the light guide plate. A transmission-type image display device.

  Yet another aspect of the present invention relates to a method of manufacturing a light guide plate that is transparent and flexible and emits as planar light from an exit surface that intersects the entrance surface. The method of manufacturing the light guide plate includes a step of manufacturing a resin sheet by continuously extruding a transparent and flexible thermoplastic resin in a molten state, a step of winding and transporting the resin sheet in a roll shape, and a resin sheet. A step of printing a plurality of light scattering portions for scattering at least a part of the light incident from the incident surface on the exit surface side, and a resin sheet on which the plurality of light scattering portions are printed And obtaining a light guide plate by cutting into a size.

  Since the resin sheet is formed by continuously extruding a molten thermoplastic resin, it is long in the extrusion direction. Since the long resin sheet is rolled and conveyed, for example, when the resin sheet is conveyed in the manufacturing process, the conveying operation is easy.

  ADVANTAGE OF THE INVENTION According to this invention, a flexible light-guide plate, the surface light source device provided with the light-guide plate, a transmissive | pervious image display apparatus, and the manufacturing method of the light-guide plate can be provided.

It is a schematic diagram of the light-guide plate which concerns on one Embodiment. It is drawing for demonstrating a total light transmittance. It is a schematic diagram of the state which wound the light-guide plate shown in FIG. 1 on the roll. It is drawing which shows schematic structure of an example of the apparatus which manufactures the light-guide plate shown in FIG. It is a flowchart of the manufacturing method of a light-guide plate. It is a schematic diagram which shows schematic structure of the transmissive image display apparatus to which a light-guide plate is applied. It is drawing which shows the modification of the manufacturing method of a light-guide plate. It is drawing which shows the modification of how to wind up a light-guide plate. It is the schematic diagram of the state wound around the roll of the modification of the light-guide plate shown in FIG. It is drawing which shows the further modification of how to wind up a light-guide plate.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. The dimensional ratios in the drawings do not necessarily match those described. In the description, words indicating directions such as “up” and “down” are convenient words based on the state shown in the drawings.

  FIG. 1 is a schematic diagram of a light guide plate according to an embodiment. The light guide plate 10 includes a light guide plate base material portion 11 having a plate shape. The light guide plate base 11 has an incident surface 11a on which light is incident, an output surface 11b that emits light, and a back surface 11c that is located on the opposite side of the output surface 11b. The entrance surface 11a is a side surface that intersects with the exit surface 11b and the back surface 11c (in FIG. 1, it is orthogonal to the exit surface 11b and the back surface 11c). The incident surface 11 a functions as the incident surface of the light guide plate 10. The exit surface 11 b functions as the exit surface of the light guide plate 10. The example of the planar view shape (shape seen from the thickness direction) of the light-guide plate base-material part 11 contains a rectangle and a square. The light guide plate base 11 guides the light incident from the incident surface 11a toward the side surface opposite to the incident surface 11a. Hereinafter, the direction from the incident surface 11a toward the side surface 11d is also referred to as a light guide direction.

  A plurality of light scattering portions 12 are provided on the back surface 11c. The light scattering unit 12 scatters light incident from the incident surface 11a. Thereby, at least a part of the light incident from the incident surface 11a and scattered by the light scattering portion 12 is propagated toward the exit surface 11b side. That is, at least a part of the light incident from the incident surface 11 a is reflected by the light scattering portion 12 toward the emission surface 11 b. The arrangement state of the plurality of light scattering portions 12 and the shape of each light scattering portion 12 may be set so that the light emitted from the emission surface 11b has desired characteristics. For example, the arrangement state of the plurality of light scattering portions 12 and the shape of each light scattering portion 12 may be set so that light with uniform luminance is emitted from the emission surface 11b. An example of the light scattering portion 12 is a light scattering dot having a lens shape, a quadrangular pyramid shape, or a plate shape. The light scattering portion 12 may be convex or concave. The light scattering portion 12 may be a convex portion or a concave portion extending in the direction orthogonal to the light guide direction on the back surface 11c. In this case, the plurality of light scattering portions 12 are arranged in parallel in the light guide direction. The light scattering portion 12 may contain diffusing particles.

  The light scattering portion 12 can be formed by, for example, a printing method. Examples of the printing method for forming the light scattering portion 12 may include silk printing, ink jet printing, and screen printing. Further, as shown in FIG. 9, the light scattering portion 12 may be formed in a concave shape by a method of irradiating laser light, and is formed in a concave shape or a convex shape by pressing a stamper on which fine unevenness is formed. May be.

  In a method using ink jet printing, a smaller light scattering portion 12 can be formed. When the light scattering portion 12 is small, it is difficult to see the light scattering portion 12 from the emission surface 11b side even if the light guide plate 10 is thin. Before the inkjet printing, a liquid repellent treatment may be performed on the back surface 11c of the light guide plate base material portion 11 as a pretreatment. Examples of the material of the light scattering portion 12 include white ink and ultraviolet curable resin.

  Examples of the liquid repellent treatment include treatment using a surface modifier as a liquid repellent treatment, treatment with various energy rays, treatment by chemical adsorption, treatment by graft polymerization on the material surface, and the like.

  The treatment using the surface modifier is a treatment for forming a liquid repellent layer to which a small amount of the surface modifier is added on the back surface 11c. Examples of the surface modifier as the liquid repellent treatment agent are vinyl polymers having a perfluoroalkyl group (Rf group) in the side chain, Rf group-containing silicone, and the like. The liquid repellent layer can be formed by a method in which a surface modifier is soaked into a paper waste and applied to the back surface 11c, or the surface modifier is sprayed on the back surface 11c by spraying or ink jet printing.

  The treatment with various energy rays is a treatment for imparting liquid repellency to the back surface 11c with the energy rays. Examples of energy rays include plasma, electron beams, ion beams, and the like. Examples of liquid repellent treatment using plasma treatment include forming a liquid repellent monomolecular film on the roughened surface after roughening the back surface 11c by plasma etching, fluorine-based gas plasma, and the like. This includes fluorination of the back surface 11c, forming a film composed of a liquid repellent compound on the back surface 11c by plasma CVD, forming a liquid repellent thin film on the back surface 11c by plasma polymerization, and the like.

  Examples of the treatment by surface roughening are the provision of uneven shapes on the back surface 11c by hot pressing, the etching by chemicals, the blast treatment and the like.

  In the treatment by chemical adsorption, it is preferable to modify the end of the adsorbed molecule with fluorine. In particular, the CF3 group is preferred as the terminal substituent from the viewpoint of liquid repellency.

  Of the examples of such treatment, fluorination of the back surface 11c with fluorine-based gas plasma is preferable because it is simple and uniform.

  Before the inkjet printing, a hydrophilic treatment may be performed on the back surface 11c of the light guide plate base material portion 11 as a pretreatment. Examples of the hydrophilization treatment include ultraviolet irradiation, contact with alcohol, and plasma treatment. Ultraviolet irradiation can be performed using a low-pressure mercury lamp, a metal halide lamp, or the like. Ultraviolet irradiation may be performed in an air atmosphere or an ozone atmosphere. The contact between the surface of the acrylic resin plate and the alcohol can be performed by, for example, a method of wiping the surface of the acrylic resin plate using a fiber base material such as a waste impregnated with alcohol. For example, isopropyl alcohol (IPA) is used as the alcohol. Plasma treatment includes corona treatment.

  Hereinafter, the configuration of the light guide plate 10 will be described in detail. The light guide plate 10 is a flexible light guide plate 10. Specifically, the light guide plate base 11 is transparent and has flexibility. The light guide plate base 11 is made of a transparent and flexible material. More specifically, the light guide plate base member 11 may be made of a so-called elastomer. Examples of the material of the light guide plate base 11 include acrylic resin, styrene resin, polymethyl methacrylate (PMMA) resin, polystyrene (PS) resin, MS (methyl methacrylate-styrene copolymer) resin, polycarbonate resin. AS (acrylonitrile-styrene copolymer) resin, cycloolefin resin, polyethylene resin, polypropylene resin, and polyethylene terephthalate resin. Preferably, the material of the light guide plate base material portion 11 may be a block copolymer of methyl methacrylate and butyl acrylate. In one embodiment, the light guide plate base part 11 may be a sheet-like molded product in which a polycarbonate resin layer is laminated on one surface or both surfaces of an acrylic resin layer. The light guide plate substrate 11 may contain additives such as a light diffusing agent, an ultraviolet absorber, an antistatic agent, an antioxidant, a processing stabilizer, a flame retardant, and a lubricant without departing from the spirit of the present invention. good.

  The light guide plate 10 may be transparent as long as light can be guided to such an extent that the light guide plate 10 can be used. In one embodiment, a predetermined sample (measuring base material portion) 20 is made of the same material (base material) as the light guide plate base material portion 11 and the total light transmittance Tt of the sample 20 is 80%. That is enough, and it is preferably 85% or more.

A method for measuring the total light transmittance Tt will be described with reference to FIG. FIG. 2 is an explanatory diagram for explaining the total light transmittance. First, a sample 20 having a length of 250 mm, a width of 40 mm, and a thickness of 2 mm was prepared using the same material as the light guide plate base material portion 11. With respect to these samples 20, light from the light source unit 30 is incident on one side surface (first side surface) 20a, and light emitted from the other side surface (second side surface) 20b opposite to the side surface 20a is emitted. Measurement is performed by the detection unit 31. The detection unit 31 is, for example, a long optical path measuring device (U-4100) manufactured by Hitachi High-Technologies Corporation. The total light transmittance Tt is expressed by the following equation (2), where Q _{in is} the amount of light entering the side surface 20a serving as the incident surface and Q _out is the amount of light output from the side surface 20b.
Tt = Q _out / Q _in (2)

  In the light guide plate 10, as shown in FIG. 1, when the thickness of the light guide plate base material portion 11 is D, in one embodiment, D is preferably 0.7 mm or less, more preferably 0. 4 mm or less.

  In one embodiment, when the light guide plate 10 is rolled into a roll shape, the innermost radius is preferably 2.5 cm or less, more preferably 1.5 cm or less. Have This will be specifically described with reference to FIGS. 3 and 9 schematically show a cross-sectional configuration when the light guide plate is wound around a roll and cut along a cross section perpendicular to the center line of the roll. In the case where the light guide plate 10 is wound around the roll 50 having a radius R, preferably, the light guide plate 10 can be wound in close contact with the roll 50 having R of 2.5 cm or less, more preferably R of 1.5 cm or less. The light guide plate 10 has the flexibility described above. The above flexibility of the light guide plate 10 can be realized if the light guide plate base material portion 11 has the same flexibility.

  When the light scattering portion 12 is a lens-shaped or dome-shaped light scattering dot as shown in FIG. 1, the planar view shape of the light scattering dot (the shape seen from the thickness direction of the light guide plate base material portion 11) is It is substantially circular. Thus, when the diameter of the light scattering portion 12 having a substantially circular planar shape is F, in one embodiment, F / D is preferably 0.33 or less, and more preferably 0.13. It is as follows.

  The light guide plate 10 having the above-described configuration can be manufactured using a manufacturing apparatus shown in FIG. FIG. 4 is a drawing showing a schematic configuration of an example of an apparatus for manufacturing the light guide plate shown in FIG. The light guide plate 10 is manufactured by extrusion using the manufacturing apparatus 40 shown in FIG.

  The manufacturing apparatus 40 forms an elongated resin sheet S by continuously extruding the raw material resin from the extruder 41 in a sheet state, and an extruder 41 that extrudes the raw material resin of the light guide plate base material portion 11 that is in a heated and melted state. And a first pressing roll 43A, a second pressing roll 43B, and a third pressing roll 43C that are sequentially spaced from each other on the downstream side of the die 42. An example of the die 42 is a T die.

  FIG. 5 is a flowchart of the method for manufacturing the light guide plate. As shown in FIG. 5, the method for manufacturing the light guide plate 10 includes a resin sheet manufacturing step S10, a transporting step S11, a printing step S12, and a cutting step S13. Each step will be described.

(Resin sheet manufacturing process S10)
The resin sheet S is manufactured using the manufacturing apparatus 40. Specifically, the raw material resin is charged into the resin charging port 41 a of the extruder 41. The extruder 41 melts and kneads the charged raw material resin. Thereafter, the extruder 41 supplies the melted and mixed raw material resin to the die 42 and continuously extrudes it from the die 42 into a sheet shape to form the resin sheet S.

  The resin sheet S discharged from the die 42 passes between the first pressing roll 43A and the second pressing roll 43B. At this time, the resin sheet S is sandwiched between the first pressing roll 43A and the second pressing roll 43B in the thickness direction and pressed by them. The resin sheet S that has passed between the first pressing roll 43A and the second pressing roll 43B is then pressed between the second pressing roll 43B and the third pressing roll 43C.

  The resin sheet S that has passed through the third pressing roll 43C has flexibility. Therefore, as shown in FIG. 4, the resin sheet S that has passed through the third pressing roll 43C is wound into a roll.

(Conveying step S11)
After winding a certain length of the resin sheet S into a roll, the resin sheet S is cut. The cutting of the resin sheet S can be performed using a cutting machine 44 disposed on the downstream side of the third pressing roll 43C. Then, the roll-shaped resin sheet S is conveyed to the place which performs a printing process. The resin sheet S wound in a roll shape is referred to as a resin sheet roll.

(Printing step S12)
A plurality of light scattering portions 12 are printed on the main surface of the resin sheet S while pulling out the resin sheet S from the resin sheet roll. An example of the printing method is the above-described method (for example, ink jet printing).

(Cutting step S13)
The light guide plate 10 is obtained by cutting the resin sheet S on which the main surface is printed into a predetermined size. The cutting of the resin sheet S can be performed using a cutting machine similar to the cutting machine 44.

  In the light guide plate 10 having the above-described configuration, light incident from the incident surface 11 a of the light guide plate base material portion 11 propagates in the light guide plate 10, specifically, in the light guide plate base material portion 11 while being totally reflected. In the propagation process, when light is scattered by the light scattering portion 12, the light scattered by the light scattering portion 12 and propagating to the emission surface 11b side is emitted from the emission surface 11b. While light incident from the incident surface 11a propagates through the light guide plate 10, a part of the light is emitted from the emission surface 11b, so that planar light is emitted from the emission surface 11b.

  Since the light guide plate 10 has flexibility, the light guide plate 10 can be wound around the roll 50 as schematically shown in FIGS. 3 and 9. As a result, for example, even the light guide plate 10 used in a large transmissive image display device such as a liquid crystal display device of 32 inches or more can be easily transported. In particular, when the light guide plate 10 has the flexibility as illustrated, the state of being wound into a roll is likely to be more compact and easy to carry. Moreover, in the illustrated manufacturing method, the light guide plate base material portion 11 can be wound into a roll shape and transported to a subsequent process, so that it is easy to transport the light guide plate.

  As shown in FIG. 1, when a plurality of light scattering portions 12 are formed on the back surface 11c of the light guide plate base material portion 11 by a printing method or the like, the back surface 11c itself is used for scattering such as an uneven shape. Less stress concentration at the position of the light scattering portion 12 when the light guide plate 10 is curved than when the processing is performed or when the light scattering portion is embedded in the light guide plate base material portion 11 it can. As a result, the durability of the light guide plate 10 can be improved.

  Furthermore, since the light guide plate 10 has flexibility, the transmissive image display device including the light guide plate 10 can also be a flexible transmissive image display device.

  FIG. 6 is a schematic diagram illustrating a schematic configuration of a transmissive image display device to which the light guide plate 10 is applied. In FIG. 6, the cross-sectional configuration of the transmissive image display device 1 is shown in an exploded manner. The transmissive image display device 1 can be suitably used as a display device for a mobile phone or various electronic devices or a television device.

  The transmissive image display device 1 includes a light guide plate 10, a light source unit 2 disposed on the side of the light guide plate 10, and a transmissive image display unit disposed on the front side of the light guide plate 10 (upper side in FIG. 1). 3. At least one optical film can be disposed between the light guide plate 10 and the transmissive image display unit 3. Examples of the optical film are a diffusion film, a prism film, a brightness enhancement film, and the like. The optical film has flexibility.

  The light source unit 2 includes a plurality of point light sources 2A arranged in a line. An example of the point light source 2A is a light emitting diode. The light source unit 2 is not limited to a point light source, and may be a linear light source such as a fluorescent lamp (cold cathode ray lamp). The light source unit 2 may include a reflector that reflects light on the side opposite to the light guide plate 10 in order to efficiently make light incident on the light guide plate 10 side.

  The light guide plate 10 and the light source unit 2 illustrated in FIG. 6 constitute a surface light source device 4 that supplies planar light to the transmissive image display unit 3. When an optical film is provided between the transmissive image display unit 3 and the light guide plate 10, the optical film may be regarded as a component of the surface light source device 4.

  The transmissive image display unit 3 is illuminated with the planar light emitted from the light guide plate 10 and displays an image. An example of the transmissive image display unit 3 is a liquid crystal display panel as a polarizing plate bonding body in which linear polarizing plates are arranged on both surfaces of a liquid crystal cell. The transmissive image display unit 3 has flexibility. The transmissive image display unit 3 having flexibility can be realized by using a soft plastic instead of a glass substrate used in a conventional liquid crystal display panel or the like.

  In the transmissive image display device 1 having the above-described configuration, the transmissive image display device 1 can be bent by providing flexibility to a housing that holds the transmissive image display unit 3, the light guide plate 10, the light source unit 2, and the like. A flexible housing can be realized by using a resin having flexibility. Usually, the housing that holds the transmissive image display unit 3, the light guide plate 10, the light source unit 2, and the like includes a front frame that holds the transmissive image display unit 3, and a rear side that holds the light guide plate 10 and the light source unit 2. Frame. The front side frame is fixed to the back side frame.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention.

  For example, you may implement printing process S12 before conveyance process S11. In this case, as shown in FIG. 7, the light scattering unit 12 is printed on the main surface of the resin sheet S by the printing unit 45 before the continuous resin sheet that has passed through the third pressing roll 43 </ b> C is wound into a roll shape. . In FIG. 7, the display of the light scattering unit 12 is omitted. The printing unit 45 is a device that performs the above-described printing method. For example, in the case of inkjet printing, the printing unit 45 includes an inkjet head.

  Alternatively, the flexible light guide plate 10 can be manufactured if a material having flexibility is used as the material of the light guide plate 10 without providing the transport step S11 for transporting the resin sheet S in a roll shape. In this case, for example, after performing the printing process on the resin sheet S that has passed through the third pressing roll 43C, a cutting step S13 that cuts the resin sheet S may be performed. Or after performing cutting process S13 with respect to the resin sheet S and obtaining the light-guide plate base material part 11, you may implement printing process S12 to the light-guide plate base material part 11. FIG.

  3 and 9, an example of how to wind the light guide plate 10 in a roll shape is shown, but the way of winding the light guide plate 10 is not limited to the form shown in FIGS. 3 and 9. For example, as shown in FIGS. 8 and 10, the light guide plate 10 may be wound so that the light scattering portion 12 is positioned inside. That is, when the light guide plate 10 is wound in a roll shape, either the emission surface 11b or the back surface 11c of the light guide plate base material portion 11 may face inward. The same applies to the case of winding up the resin sheet S on which the light scattering portion 12 is printed, as shown in FIG.

  3, 8, 9, and 10, in order to clearly show the configuration of the light guide plate 10, the light guide plate base material portion 11 and the light scattering portion 12, particularly the light scattering portion 12, are illustrated with a large size. Yes. However, for example, the thickness of the light scattering portion 12 is usually 100 μm or less and often 50 μm or less. That is, when the flexibility of the light guide plate 10 is defined by the innermost radius when the light guide plate 10 is wound in a roll shape, the thickness of the light scattering portion 12 is small enough to be ignored. Therefore, even if the light guide plate 10 is wound around the roll 50 as the core so that the light scattering portion 12 is inside, the radius of the roll 50 is wound into a roll shape as in the case of FIGS. It may be regarded as the innermost radius of the light guide plate 10. Alternatively, when the light guide plate 10 is wound in a roll shape so that the light scattering portion 12 is on the inside, the radius may be determined based on the back surface 11c of the light guide plate base material portion 11. 3, 8, 9, and 10, the light guide plate 10 is wound around a roll 50 as a core. However, the light guide plate 10 is wound so that the light scattering portion 12 is on the inner side. The same applies to the case where the roll 50 as the core is not used.

  A plurality of convex portions may be formed on the emission surface 11b. Each convex portion extends in the light guide direction of the light incident from the incident surface 11a, that is, the direction from the incident surface 11a toward the side surface 11d. Examples of the shape of the cross section of the convex portion orthogonal to the extending direction of the convex portion include a lens shape such as a lenticular lens and a prism shape. The plurality of convex portions are arranged in parallel in a direction orthogonal to the light guide direction. Such a convex part forms the transfer type | mold for forming a some convex part in any of the 1st press roll 43A, the 2nd press roll 43B, and the 3rd press roll 43C, for example, Can be formed. By providing a plurality of convex portions on the emission surface 11b, the straightness of light incident on the light guide plate 10 is improved. As a result, local dimming control can be performed when the light guide plate 10 is used in the transmissive image display device 1.

  Furthermore, although one side surface is illustrated as the incident surface 11a of the light guide plate base material portion 11, light may be incident on the light guide plate base material portion 11 from a side surface other than the illustrated incident surface 11a. For example, the side surface 11d can also function as an incident surface. Furthermore, either one or both of the other two side surfaces that intersect (for example, orthogonal to) the incident surfaces 11a and 11d in the light guide plate base material portion 11 may function as the incident surface.

DESCRIPTION OF SYMBOLS 1 ... Transmission type image display apparatus, 2 ... Light source part, 3 ... Transmission type image display part, 4 ... Surface light source device, 10 ... Light guide plate, 11 ... Light guide plate base material part, 11a ... Incident surface, 11b ... Output surface, 11c ... back surface, 12 ... light scattering portion, 20 ... sample (measuring base material portion), 20a ... incidence surface, 20b ... side surface.

Claims (9)

A light guide plate that emits light incident from an incident surface as planar light from an exit surface that intersects the incident surface,
A light guide plate base material portion made of a transparent and flexible material has the entrance surface and the exit surface,
Light guide plate. In the light guide plate base material portion, a plurality of light scattering portions that are provided on the back surface located on the opposite side of the light exit surface and scatter at least part of the light incident from the light entrance surface to the light exit surface side. In addition,
The light guide plate according to claim 1. The material of the light guide plate base material portion is a material in which the total light transmittance of the measurement base material portion made of the material is 80% or more,
The measurement base material part is a rectangular parallelepiped having a longitudinal length of 250 mm in a plan view shape,
The amount of light incident from the first side surface orthogonal to the longitudinal direction and emitted from the second side surface opposite to the first side surface is defined as _Qout, and the amount of light incident on the first side surface is When the quantity is Q _in ,
The total light transmittance is defined by Q _out / Q _in .
The light guide plate according to claim 1 or 2.   The light guide plate according to any one of claims 1 to 3, wherein the light guide plate has flexibility such that an innermost radius becomes 2.5 cm or less when wound in a roll shape. The light guide plate base material has a thickness of 0.7 mm or less.
The light guide plate according to claim 1. In the light guide plate base material portion, a plurality of light scattering portions that are provided on the back surface located on the opposite side of the light exit surface and scatter at least a part of the light incident from the light entrance surface to the light exit surface side. In addition,
The light scattering portion is a light scattering dot having a substantially circular shape in plan view,
When the thickness of the light guide plate substrate portion is D and the diameter of the light scattering portion is F, F / D is 0.33 or less.
The light guide plate according to claim 1. The light guide plate according to any one of claims 1 to 6,
A light source for supplying light to the incident surface of the light guide plate;
A surface light source device comprising: The light guide plate according to any one of claims 1 to 6,
A light source for supplying light to the incident surface of the light guide plate;
A transmissive image display unit that receives planar light from the light guide plate and displays an image;
A transmissive image display device. A method for producing a light guide plate that is transparent and flexible and emits as planar light from an exit surface that intersects an entrance surface,
A process of producing a resin sheet by continuously extruding a transparent and flexible thermoplastic resin in a molten state;
A step of winding and transporting the resin sheet in a roll shape;
Printing a plurality of light scattering portions on the main surface of the resin sheet for scattering at least part of the light incident from the incident surface to the exit surface;
A step of obtaining a light guide plate by cutting the resin sheet printed with the plurality of light scattering portions into a predetermined size;
Comprising
Manufacturing method of light guide plate.

Images