JP2013069683A - Light guide plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light guide plate capable of improving luminance, a surface light source including the light guide plate, and a transmission type image display apparatus.SOLUTION: The light guide plate 50 includes a platy body 51 and a plurality of lenses 52. The body 51 includes a first face 51a which extends in one direction and in which a plurality of convex line parts 55 are arranged in parallel in a direction almost orthogonally crossing the one direction, a second face 51b on the opposite side of the first face 51a, and incident surfaces 51c, 51d which cross the first and the second faces 51a, 51b and into which light is made incident. Each of the plurality of the lenses 52 is formed on the second face 51b in the body 51, and is convex toward the opposite side to the side of the first face 51a, when viewed from the second face 51b.

Description

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

  2. Description of the Related Art A transmissive image display device such as a liquid crystal display device generally includes a surface light source device that is disposed on the back side of a transmissive image display unit such as a liquid crystal display panel and supplies a backlight to the transmissive image display unit. As such a surface light source device, an edge light type surface light source device is known (see, for example, Patent Document 1).

  The edge light type surface light source device includes a light-transmitting light guide plate and a light source that is disposed on the side of the light guide plate and supplies light to the side surface of the light guide plate. White dots for reflecting light are provided on the back side of the light guide plate. In this configuration, the light output from the light source enters the light guide plate from the side surface of the light guide plate facing the light source, and propagates while totally reflecting in the light guide plate. Since a plurality of white dots are formed on the back side of the light guide plate (see, for example, Patent Document 1), the light reflected by the white dots is emitted from the exit surface on the transmissive image display unit side of the light guide plate.

JP 2005-38768 A

  However, in the light guide plate having white dots, the light incident on the light guide plate is not sufficiently emitted from the emission surface, and the luminance cannot be sufficiently improved.

  Therefore, an object of the present invention is to provide a light guide plate capable of improving luminance, a surface light source device including the light guide plate, and a transmissive image display device.

  The light guide plate according to the present invention extends in one direction and is opposite to the first surface and the first surface on which a plurality of protruding strips arranged in parallel in a direction substantially orthogonal to the one direction are formed. Formed on the second surface of the main body, and a plate-like main body having a second surface on the side and a surface intersecting the first and second surfaces, and an incident surface on which light is incident. And a plurality of lens portions that are convex on the side opposite to the side having the first surface when viewed from the second surface.

  A surface light source device according to the present invention includes the above-described light guide plate and a light source unit that is disposed to face an incident surface of the light guide plate and supplies light to the incident surface.

  The transmission type image display device according to the present invention is arranged to face the light guide plate described above, the incident surface of the light guide plate, a light source unit that supplies light to the incident surface, and a first light guide plate. A transmissive image display unit that is provided on the surface side and is illuminated with light emitted from the light guide plate and displays an image.

  In the light guide plate, the surface light source device, and the transmissive image display device configured as described above, the light incident from the incident surface of the light guide plate propagates while totally reflecting inside the light guide plate. When light propagating in the light guide plate enters the lens unit provided on the second surface, the light is reflected by the lens unit under conditions different from the total reflection conditions. Therefore, the light reflected by the lens unit is emitted from the first surface of the main body unit. Since the convex portion is formed on the first surface, the light emission efficiency is increased. By these actions, the luminance is improved. In the transmissive image display device according to the present invention, since the transmissive image display unit is provided on the light guide plate, the transmissive image display unit is illuminated with light having higher luminance. As a result, it is possible to improve the luminance of the image displayed on the transmissive image display unit.

  In the light guide plate, the surface light source device, and the transmissive image display device according to the present invention, the ridges formed on the first surface can be lenticular lenses or prisms.

  According to the present invention, a light guide plate capable of improving luminance, a surface light source device including the light guide plate, and a transmissive image display device can be provided.

It is a schematic diagram which shows schematic structure of the transmissive image display apparatus to which one Embodiment of the light-guide plate which concerns on this invention is applied. It is a top view at the time of seeing the light-guide plate shown in FIG. 1 from the back side. It is a side view at the time of seeing the light-guide plate shown in FIG. 1 from the light source side. It is drawing for demonstrating the example of the external shape of a protruding item | line part. It is drawing which shows the example of the cross-sectional shape of a protruding item | line part. It is drawing which shows the example of the cross-sectional shape of a protruding item | line part. It is drawing which shows the example of the cross-sectional shape of a protruding item | line part. It is drawing for demonstrating the example of the external shape of a lens part. It is a graph which shows the conditions which prescribe | regulate the external shape of a lens part. It is drawing which shows the external shape of a lens part. It is drawing which shows the result of having calculated by observation the aspect-ratio [ _hIIa / _wIIa ] of the lens part formed by the inkjet method, and the sharpening method _kIIa . It is drawing which shows the range of the aspect-ratio [ _hIIa / _wIIa ] of the lens part formed by the inkjet method, and the sharpening method _kIIa . Shown in FIG. 12 is a table showing the kurtosis how _{k IIa} and aspect ratio _{[h IIa / w} IIa] and de determined lens curvature radius _{r II} of the tip to the width _{w IIa} shape. Shown in FIG. 12 is a table showing the kurtosis how _{k IIa} and aspect ratio _{[h IIa / w} IIa] and de determined lens curvature radius _{r II} of the tip to the width _{w IIa} shape. FIG. 13 is a chart showing a lens bottom angle γ _II determined by the sharpening method k _IIa and the aspect ratio [h _IIa / w _IIa ] shown in FIG. 12; FIG. 13 is a chart showing a lens bottom angle γ _II determined by the sharpening method k _IIa and the aspect ratio [h _IIa / w _IIa ] shown in FIG. 12; It is a graph which shows the conditions which prescribe | regulate the external shape of a lens part. It is a schematic diagram which shows a simulation model. It is drawing which shows the coverage distribution of the micro lens formed in the back side of the light-guide plate used for simulation. It is drawing which shows the coverage distribution of the micro lens formed in the back side of the light-guide plate used for simulation. It is drawing which shows the directional characteristic of the point light source used for simulation. It is a graph which shows the result of simulation. It is drawing which shows the example (embodiment A1) of the other cross-sectional shape of a protruding item | line part. It is drawing which shows the example (embodiment A2) of the other cross-sectional shape of a protruding item | line part. It is drawing which shows the example (embodiment A3) of the other cross-sectional shape of a protruding item | line part. It is drawing which shows the example (embodiment A4) of the other cross-sectional shape of a protruding item | line part. It is drawing which shows the example (embodiment A5) of the other cross-sectional shape of a protruding item | line part. It is drawing which shows the part of other cross-sectional shape of a protruding item | line part. It is a figure which shows the relationship (embodiment A1, A2) of line segment length L and inclination | tilt angle (alpha) in the other cross-sectional shape of a protruding item | line part. It is a figure which shows the relationship (embodiment A3, A4) of line segment length L and inclination | tilt angle (alpha) in the other cross-sectional shape of a protruding item | line part. It is a figure which shows the relationship (embodiment A5) of line segment length L and inclination | tilt angle (alpha) in the other cross-sectional shape of a protruding item | line part. It is a figure which shows the relationship between line segment length L of other cross-sectional shape of a protruding item | line part, and (DELTA) (alpha) / (DELTA) L. It is drawing which shows the example (embodiment B1) of the other cross-sectional shape of a protruding item | line part. It is drawing which shows the example (embodiment B2) of the other cross-sectional shape of a protruding item | line part. It is drawing which shows the example (embodiment B3) of the other cross-sectional shape of a protruding item | line part. It is drawing which shows the example (embodiment B4) of the other cross-sectional shape of a protruding item | line part. It is drawing which shows the example (embodiment B5) of the other cross-sectional shape of a protruding item | line part. It is drawing which shows the part of other cross-sectional shape of a protruding item | line part. It is a figure which shows the relationship (embodiment B1, B2) of line segment length L and inclination | tilt angle (alpha) in the other cross-sectional shape of a protruding item | line part. It is a figure which shows the relationship (embodiment B3, B4) of the line segment length L and inclination | tilt angle (alpha) in the other cross-sectional shape of a protruding item | line part. It is a figure which shows the relationship (embodiment B5) of the line segment length L and inclination | tilt angle (alpha) in the other cross-sectional shape of a protruding item | line part. It is a figure which shows the relationship between line segment length L of other cross-sectional shape of a protruding item | line part, and (DELTA) (alpha) / (DELTA) L.

  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. Further, 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 showing a schematic configuration of a transmissive image display device to which an embodiment of a light guide plate according to the present invention is applied. In FIG. 1, the sectional configuration of the transmissive image display device 10 is shown in an exploded manner. The transmissive image display device 10 can be suitably used as a display device or a television device of a mobile phone or various electronic devices.

  The transmissive image display device 10 includes a transmissive image display unit 20 and a surface light source device 30 that outputs planar light to be supplied to the transmissive image display unit 20. Hereinafter, for convenience of description, as illustrated in FIG. 1, the direction in which the transmissive image display unit 20 is arranged with respect to the surface light source device 30 is referred to as a Z-axis direction or a front direction. Two directions orthogonal to the Z-axis direction are referred to as an X-axis direction and a Y-axis direction. The X-axis direction and the Y-axis direction are orthogonal to each other.

  The transmissive image display unit 20 displays an image by being illuminated with planar light emitted from the surface light source device 30. An example of the transmissive image display unit 20 is a liquid crystal display panel as a polarizing plate bonding body in which linear polarizing plates 22 and 23 are arranged on both surfaces of a liquid crystal cell 21. In this case, the transmissive image display device 10 is a liquid crystal display device (or a liquid crystal television). As the liquid crystal cell 21 and the polarizing plates 22 and 23, those used in a transmissive image display device such as a conventional liquid crystal display device can be used. Examples of the liquid crystal cell 21 are a TFT (Thin Film Transistor) type liquid crystal cell, a STN (Super Twisted Nematic) type liquid crystal cell, and the like.

  The surface light source device 30 is an edge light type backlight unit that supplies a backlight to the transmissive image display unit 20. The surface light source device 30 includes a light guide plate 50 and light source units 60 and 60 arranged to face the side surfaces 50a and 50b of the light guide plate 50 facing each other.

  The light source units 60, 60 have a plurality of point light sources 61 arranged in a line (in FIG. 1, arranged in the Y-axis direction). An example of the point light source 61 is a light emitting diode. The light source unit 60 may include a reflector as a reflection unit that reflects light on the side opposite to the light guide plate 50 in order to make light incident on the light guide plate 50 efficiently. Here, the light source unit 60 including the plurality of point light sources 61 is illustrated, but the light source unit 60 may be a linear light source such as a cold cathode fluorescent lamp (CCFL).

  The surface light source device 30 may include a reflection unit 70 located on the opposite side of the light transmission plate 50 from the transmissive image display unit 20. The reflection unit 70 is for causing the light emitted from the light guide plate 50 to the reflection unit 70 side to enter the light guide plate 50 again. The reflection unit 70 may be a sheet as shown in FIG. Further, the reflection unit 70 may be a bottom surface of the housing of the surface light source device 30 that houses the light guide plate 50 and that is mirror-finished.

  The light guide plate 50 will be described with reference to FIGS. FIG. 2 is a plan view when the light guide plate 50 shown in FIG. 1 is viewed from the back side. FIG. 3 is a left side view when the light guide plate 50 shown in FIG. 1 is viewed from the left side. Examples of the planar view shape of the light guide plate 50 include a substantially rectangular shape and a substantially square shape.

  The light guide plate 50 is opposite to the plate-shaped main body 51 in which the convex strips 55 are formed on the side that becomes the emission surface (first surface) 51a of the main body 51 and the surface on which the convex strips 55 are formed. And a plurality of lens portions 52 formed on the side which becomes the back surface (second surface) 51b of the main body portion 51 on the side. The main body 51 is made of a translucent material (or a transparent material). Examples of the refractive index of the translucent material are 1.46 to 1.62. Examples of the translucent material are a translucent resin material and a translucent glass material. Examples of the translucent resin material include polycarbonate resin (refractive index: 1.59), MS resin (methyl methacrylate-styrene copolymer resin) (refractive index: 1.56-1.59), polystyrene resin (refractive index). Ratio: 1.59), AS resin (acrylonitrile-styrene copolymer resin) (refractive index: 1.56-1.59), acrylic ultraviolet curable resin (refractive index: 1.46-1.58), poly And methyl methacrylate (PMMA) (refractive index: 1.49). As the translucent resin material, PMMA is more preferable from the viewpoint of transparency.

  As shown in FIGS. 1-3, the main-body part 51 cross | intersects the output surface 51a mutually opposed to the transmissive image display part 20, the back surface 51b on the opposite side to the output surface 51a, and the output surface 51a and the back surface 51b. It has two side surfaces 51c, 51d, 51e, 51f. FIG. 1 shows two side surfaces 51c and 51d that face each other in the X-axis direction. The side surface 51 c and the side surface 51 d are also the side surface 50 a and the side surface 50 b facing the light source unit 60. In this case, the side surface 51c and the side surface 51d are incident surfaces on which light from the light source unit 60 is incident. Of the four side surfaces 51c, 51d, 51e, 51f of the main body 51, the remaining two side surfaces 51e, 51f (see FIG. 3) face each other in the Y-axis direction. In FIGS. 1 and 3, as an example of the positional relationship between the side surfaces 51c, 51d, 51e, and 51f and the exit surface 51a and the back surface 51b, the side surfaces 51c, 51d, 51e, and 51f are substantially omitted from the exit surface 51a and the back surface 51b. The state which is orthogonal is shown.

  Next, the ridge part 55 formed in the output surface 51a side of the main-body part 51 is demonstrated. Here, for simplification of description, the description will be made assuming that the sizes of the plurality of ridge portions 55 are the same. The ridge 55 is transparent and emits light from the light guide plate 50 toward the transmissive image display unit 20. Further, the outer shape of the ridge portion 55 is the outer shape of a lenticular lens as shown in FIG.

  The plurality of ridge portions 55 extend along the X-axis direction shown in FIGS. 1 and 3 and are arranged in parallel in the Y-axis direction. The cross-sectional shape orthogonal to the extending direction of the ridges 55 is substantially uniform. As shown in FIGS. 3 and 4, the plurality of ridges 55 can be arranged with a certain distance S between the ridges 55 adjacent in the short side direction (Y-axis direction). A flat portion 55c is formed between the bottom portions 55b, which are the ends of the ridge portions 55 adjacent to each other. The coverage of the plurality of ridges 55 on the emission surface 51 a of the main body 51 can be adjusted by changing the distance S. For example, if the protruding ridges 55 adjacent to each other in the short side direction are arranged without a gap, and the positions of the bottoms 55b that are the ends of the adjacent protruding ridges 55 coincide with each other (the distance S shown in FIG. 4 is 0). The coverage is 100%. The coverage of the plurality of ridges 55 on the emission surface 51a of the main body 51 is usually 50% to 100%.

  Next, various examples of the outer shape of the ridge 55 will be described. Here, for convenience of explanation, the reference plane 51g is defined. That is, the reference surface 51g is a plane parallel to a line connecting the bottom portions 55b described later (shown by a one-dot chain line in FIG. 4) in the cross section of the protruding portion 55 as shown in FIG. It is defined as a plane that forms the bottom surface of 55. In the present embodiment, the back surface 51b (see FIG. 1) and the reference surface 51g of the light guide plate 50 are parallel to each other.

For example, the outer shape of the ridge 55 is a shape defined by a combination of the aspect ratio [h _Ia / w _Ia ], the radius of curvature [r _I / w _Ia ] and the bottom angle γ _{I shown} below. Can do. Hereinafter, the aspect ratio [h _Ia / w _Ia ], the radius of curvature [r _I / w _Ia ] and the bottom angle γ _I will be described with reference to FIG.

(I) Aspect ratio [h _Ia / w _Ia ]
Aspect ratio _[h Ia _{/ w Ia],} in FIG. 4, width _{w Ia (μm)} of the convex portion 55, when the maximum height of the convex portion 55 was set to _{h Ia} ([mu] m), a width _{w Ia Is} the ratio of the maximum height h _Ia to.

(II) Radius of curvature with respect to width [r _I / w _Ia ]
The radius of curvature [r _I / w _Ia ] with respect to the width is the width w when the width of the _ridge 55 is w _Ia (μm) and the radius of curvature of the tip 55a of the ridge 55 is r _I (μm). which is the ratio of the radius of curvature _{r I} for _Ia. The radius of curvature r _I of the distal end portion 55a represents the degree of bending of the distal end portion 55a as the top of the ridge 55. For example, as shown in FIG. 4, the radius of curvature r _I of the tip 55a is a radius of a circle assuming a circle (a circle indicated by a broken line in FIG. 4) in contact with the tip 55a.
(III) Bottom angle γ _I
Bottom angle gamma _I is between the tangent plane P _I and the reference surface 51g of the convex portion 55 at the position of intersection of the contour and the reference plane 51g of the convex portion 55 in a cross section perpendicular to the extending direction It is an angle to make. The bottom of the tip 55a is also the skirt of the ridge 55. Thus, the bottom angle γ _I is also the skirt angle.

FIG. 4 shows a cross-sectional configuration orthogonal to the extending direction of the ridges 55. w _Ia is the width of the ridge 55. In addition, h _Ia is the thickness at the position of the tip end portion 55 a of the ridge 55. Therefore, the aspect ratio [h _Ia / w _Ia ] is the thickness (or height) of the ridge 55 at the position of the tip 55a with respect to the width of the ridge 55, ie, the thickness at the position of the tip. Corresponding to [width] / [width of ridge]. Usually, since the thickness of the protrusion 55 at the position of the tip 55a is the maximum, the thickness of the protrusion 55 at the position of the tip 55a is also the maximum thickness of the protrusion 55. The ratio described in the above (II), the ratio between the width of the curvature radius r _I and the ridges 55, i.e., corresponding to the curvature radius] / [the width of the convex portion.

In addition to the above conditions (I) to (III), the outer shape of the ridge 55 can also be defined as a conic curve represented by the following formula (1). In FIG. 5, the u _I v _I coordinate system is set with the parallel direction (Y-axis direction) orthogonal to the extending direction (X-axis direction) of the ridges 55 shown in FIGS. 1 and 3 as the u _I- axis. Yes. Here, u _I axis corresponds to an axis parallel to (Y-axis) in parallel direction of the plurality of convex portions 55. The v _I axis corresponds to an axis (Z axis) parallel to the thickness direction of the light guide plate 50. In the u _I v _I plane of the u _I v _I coordinate system, the cross-sectional shape of the ridge portion 55 is such that both end portions 55b and 55b are located on the u _I axis and the distal end portion 55a is located on the v _I axis. In this case the ridges 55, the outer shape, such as the angle between the tangent plane P _I and the reference surface 51g is decreased monotonically from the bottom 55b side of the convex portion 55 to the distal end portion 55a side in contact with the convex portion 55 It can be.

In Formula (1), w _Ia is the length of the ridge portion 55 in the u _I axis direction, and h _Ia is the ridge portion 55 when the ridge portion 55 has a shape indicated by v _I (u _I ). Corresponds to the maximum height between the two end portions 55b and 55b. k _Ia is a parameter indicating how the tip 55a of the ridge 55 is sharpened. For example, when the sharpening method k _Ia is 0, the outer shape of the ridge 55 is a parabolic shape, when the sharpening method k _Ia is 1, the outer shape of the ridge 55 is a prism shape, and when the sharpening method k _Ia is −1. The outer shape of the ridge portion 55 is a shape obtained by cutting an ellipse in half.

Furthermore, the outer shape of the ridge portion 55 is defined by a combination of the aspect ratio [h _Ia / w _Ia ] and the sharpening method k _Ia when the contour line of the ridge portion 55 is expressed by a predetermined conical curve. Can do. Examples of these combinations include the following (A) and (B).
(A) h _Ia / w _Ia = 0.390, k _Ia = −0.390
(B) h _Ia / w _Ia = 0.232, k _Ia = 0.021

FIG. 5 shows a cross-sectional shape defined by the combination of (A) (h _Ia / w _Ia = 0.390, k _Ia = −0.390). FIG. 6 shows a cross-sectional shape defined by the combination (B) (h _Ia / w _Ia = 0.232, k _Ia = 0.021). The coverage of the plurality of ridges 55 on the exit surface 51a of the main body 51 can be appropriately set by adjusting the distance S between the ridges 55 adjacent in the short side direction (Y-axis direction). Cross-sectional shape of the convex portion 55 has a symmetrical contour relative to v _I axis. An example of the width w _Ia is not less than 10 μm and not more than 2 mm, preferably not less than 20 μm and not more than 1 mm, more preferably not less than 50 μm and not more than 600 μm.

Moreover, the external shape of the protruding line part 55 can also be prescribed _| regulated by the combination of aspect-ratio [ _hIa / _wIa ] shown to the following (C), and the sharpening method kIa.
(C) h _Ia / w _Ia = 0.500, k _Ia = 1.000
FIG. 7 shows a cross-sectional shape defined by the combination (h _Ia / w _Ia = 0.500, k _Ia = 1.000) of the above (C). Also in this case, the coverage of the plurality of ridges 55 on the emission surface 51a of the main body 51 is appropriately set by adjusting the distance S between the ridges 55 adjacent in the short side direction (Y-axis direction). Can do. Cross-sectional shape of the convex portion 55 has a symmetrical contour relative to v _I axis. An example of the width w _Ia is not less than 10 μm and not more than 2 mm, preferably not less than 20 μm and not more than 1 mm, more preferably not less than 50 μm and not more than 600 μm.

  Next, the lens unit 52 will be described. In order to simplify the description, it is assumed that the plurality of lens portions 52 have the same size. As shown in FIGS. 1 and 2, the plurality of lens portions 52 are formed on the back surface 51 b of the main body portion 51. The lens part 52 is transparent and is for emitting light propagating through the light guide plate 50 from the emission surface 51a side. The outer shape of each lens part 52 is a dome shape.

  As shown in FIG. 2, the plurality of lens parts 52 are arranged in a lattice pattern in the short side direction (Y-axis direction) and the long side direction (X-axis direction) of the main body part 51, and the emission surface of the light guide plate 50. The coverage distribution is optimized so that the emitted light quantity uniformity from 51a is 95%. As an example of satisfying such an emitted light quantity uniformity, the coverage of one lens part 52 with respect to a square lattice at the center part of the back surface 51b can be 78.54%. The lens portions 52 can also be arranged in a staggered lattice shape or a hexagonal close-packed lattice shape. Further, the coverage can be adjusted without molding the lens portion 52 even at a location corresponding to each lattice.

Next, the shape of each lens unit 52 will be described. Figure 8 is a view for explaining an example of the outer shape of the lens unit 52 is a schematic diagram of a sectional configuration of the light guide plate 50 including the center axis line C _II of the lens unit 52. In the lens portion 52, the top portion of the lens portion 52 is referred to as a tip portion 52 a of the lens portion 52, and the skirt portion of the lens portion 52 is referred to as a bottom portion 52 b of the lens portion 52. In the present embodiment, the shape of the lens unit 52 is assumed to be a shape obtained by rotating the cross-sectional shape shown in FIG. 8 around the central axis _CII as a rotation axis. Therefore, the shape of the lens unit 52 becomes symmetrical in any cross-section including the center axis line C _II. Further, the lens unit 52, the angle formed between the tangent plane P _II and rear 51b in contact with the lens unit 52, has an outer shape such that monotonically decreases from the bottom 52b side of the lens portion 52 to the distal end portion 52a side Yes.

Various examples of the outer shape of the lens unit 52 will be described. For example, the outer shape of the lens unit 52 is a shape defined by a combination of the aspect ratio [h _IIa / w _IIa ], the radius of curvature [r _II / w _IIa ], and the bottom angle γ _II shown in the chart of FIG. can do. Hereinafter, the aspect ratio [h _IIa / w _IIa ], the radius of curvature [r _II / w _IIa ], and the bottom angle γ _II will be described with reference to FIG.

(I) Aspect ratio [h _IIa / w _IIa ]
The aspect ratio [h _IIa / w _IIa ] is the maximum with respect to the width w _IIa when the width of the lens portion 52 is w _IIa (μm) and the maximum height of the lens portion 52 is h _IIa (μm) in FIG. It is the ratio of the height h _IIa .

(II) Radius of curvature with respect to width [r _II / w _IIa ]
The radius of curvature [r _II / w _IIa ] with respect to the width refers to the width w _IIa when the width of the lens portion 52 is w _IIa (μm) and the radius of curvature of the tip 52a of the lens portion 52 is r _II (μm). which is the ratio of the radius of curvature _{r II.} The radius of curvature r _II of the tip portion 52a is representative of the curvature of the tip portion 52a of the top portion of the lens portion 52. For example, the radius of curvature r _II of the tip portion 52a, as shown in FIG. 8, the radius of a circle assuming a circle tangent to the tip portion 52a (a circle indicated by a broken line in FIG. 8).
(III) Bottom angle γ _II
The bottom angle γ _II is an angle formed between the tangent plane P _II of the lens unit 52 and the back surface 51b at the intersection of the contour line of the lens unit 52 and the back surface 51b in a cross section passing through the central axis C _II. . The bottom angle γ _II corresponds to a contact angle when the lens unit 52 is regarded as a droplet. Further, the bottom 52b is also a skirt of the lens 52 with respect to the tip 52a. Thus, the bottom angle γ _II is also the skirt angle.

Hereinafter, the conditions of the outer shape satisfied by the lens unit 52 according to the case classification based on the aspect ratio [h _a / w _a ] shown in the chart of FIG. 9 will be specifically exemplified.

(1) When 0.07 ≦ h _IIa / w _IIa <0.09 The outer shape of the lens portion 52 is a shape in which r _II / w _IIa and γ _II (°) satisfy the following conditions.
0.8594 ≦ r _II / w _IIa ≦ 1.7969 and 12.46 ≦ γ _II ≦ 20.69

(2) When 0.09 ≦ h _IIa / w _IIa <0.11 The outer shape of the lens portion 52 is such that r _II / w _IIa and γ _II (°) satisfy the following conditions.
0.5625 ≦ r _II / w _IIa ≦ 1.4375 and 14.48 ≦ γ _II ≦ 25.26

(3) When 0.11 ≦ h _IIa / w _IIa <0.13 The outer shape of the lens portion 52 is such that r _II / w _IIa and γ _II (°) satisfy the following conditions.
0.4688 ≦ r _II / w _IIa ≦ 1.1979 and 17.22 ≦ γ _II ≦ 29.52

(4) When 0.13 ≦ h _IIa / w _IIa <0.15 The outer shape of the lens portion 52 is such that r _II / w _IIa and γ _II (°) satisfy the following conditions.
0.4018 ≦ r _II / w _IIa ≦ 1.4732 and 19.88 ≦ γ _II ≦ 58.14

(5) When 0.15 ≦ h _IIa / w _IIa <0.17 The outer shape of the lens portion 52 is such that r / w _IIa and γ _II (°) satisfy the following conditions.
0.2734 ≦ r _II / w _IIa ≦ 1.2891 and 21.22 ≦ γ _II ≦ 61.44

(6) When 0.17 ≦ h _IIa / w _IIa <0.19 The outer shape of the lens portion 52 is a shape in which r _II / w _IIa and γ _II (°) satisfy the following conditions.
0.2431 ≦ r _II / w _IIa ≦ 1.1458 and 23.59 ≦ γ _II ≦ 64.16

(7) When 0.19 ≦ h _IIa / w _IIa <0.21 The outer shape of the lens portion 52 is such that r _II / w _IIa and γ _II (°) satisfy the following conditions.
0.2188 ≦ r _II / w _IIa ≦ 1.2188 and 25.88 ≦ γ _II ≦ 86.33

(8) When 0.21 ≦ h _IIa / w _IIa <0.23 The outer shape of the lens portion 52 is a shape in which r _II / w _IIa and γ _II (°) satisfy the following conditions.
0.3125 ≦ r _II / w _IIa ≦ 1.1080 and 31.28 ≦ γ _II ≦ 86.68

(9) When 0.23 ≦ h _IIa / w _IIa <0.25 The outer shape of the lens part 52 is a shape in which r _II / w _IIa and γ _II (°) satisfy the following conditions.
0.2865 ≦ r _II / w _IIa ≦ 1.0156 and 33.53 ≦ γ _II ≦ 86.96

(10) When 0.25 ≦ h _IIa / w _IIa <0.27 The outer shape of the lens part 52 is a shape in which r _II / w _IIa and γ _II (°) satisfy the following conditions.
0.4567 ≦ r _II / w _IIa ≦ 0.9375 and 44.76 ≦ γ _II ≦ 87.20

(11) When 0.27 ≦ h _IIa / w _IIa <0.29 The outer shape of the lens portion 52 is such that r _II / w _IIa and γ _II (°) satisfy the following conditions.
0.6920 ≦ r _II / w _IIa ≦ 0.7813 and 68.14 ≦ γ _II ≦ 77.44

(12) When 0.29 ≦ h _IIa / w _IIa <0.31 The outer shape of the lens portion 52 is a shape in which r _II / w _IIa and γ _II (°) satisfy the following conditions.
0.6458 ≦ r _II / w _IIa ≦ 0.7292 and 69.47 ≦ γ _II ≦ 78.25

8, it indicates the configuration of the section including the center axis C _II of the lens unit 52, the width w _IIa is maximum width corresponding lens portion 52. Further, h _IIa is the thickness at the position of the tip end portion 52 a of the lens portion 52. Therefore, the aspect ratio [h _IIa / w _IIa ] is the thickness (or height) of the lens part 52 at the position of the tip part 52a with respect to the maximum width of the lens part 52, that is, the thickness at the position of the tip part. ] / [Maximum lens width]. Normally, the thickness of the lens portion 52 at the position of the tip portion 52a is the maximum, and therefore the thickness of the lens portion 52 at the position of the tip portion 52a is also the maximum thickness of the lens portion 52. The ratio described in the above (II), the ratio of the maximum width of the radius of curvature r _II and the lens unit 52, i.e., corresponding to the curvature radius] / [maximum width of the lens unit.

Further, the outer shape of the lens unit 52 can also be defined in the cross-sectional configuration of the lens unit 52 including the center axis line C _II of the lens unit 52 as shown in FIG. 10, the contour of the lens unit 52 as a conic. Specifically, as shown in FIG. 10, a u _II v _II coordinate system is set, and the cross-sectional shape of the lens portion 52 can be defined by a conic curve v _II (u _II ) represented by the following formula (2). . The v _II axis of the u _II v _II coordinate system corresponds to the central axis C _II of the lens unit 52 in FIG. The u _II axis corresponds to the X-axis direction shown in FIGS.

In Expression (2), k _IIa is a parameter indicating how the conic curve represented by Expression (2) is sharpened, and represents how the tip 52a of the lens part 52 is sharpened. For example, when the sharpening method k _IIa is 0, the outer shape of the lens unit 52 is a parabolic shape, when the sharpening method k _IIa is 1, the outer shape of the lens unit 52 is a prism shape, and when the sharpening method k _IIa is −1, the lens The outer shape of the portion 52 is a shape obtained by cutting an ellipse in half.

Further, the outer shape of the lens unit 52 can be defined by a combination of the aspect ratio [h _IIa / w _IIa ] and the sharpening method k _IIa when the contour line of the lens unit 52 is expressed as a predetermined conical curve. . Examples of these combinations include the following combinations (a) to (c).
(A) h _IIa / w _IIa = 0.220, k _IIa = 0.200
(B) _hIIa / _wIIa = 0.120, _kIIa = 0.400
(C) h _IIa / w _IIa = 0.220, k _IIa = 0.000

An example of the width w _IIa is not less than 5 μm and not more than 1 mm, preferably not less than 10 μm and not more than 500 μm. The lens unit 52 having such a size is a so-called microlens.

  The material of the lens part 52 and the protruding line part 55 can be the same material as the main body part 51. Moreover, the material of the lens part 52 and the protruding item | line part 55 may be different from the material of the main-body part 51, if it is a translucent material.

  The main body 51 of the light guide plate 50 configured as described above may be a single-layer plate-like body made of a single translucent material, or layers made of different translucent materials are laminated. A plate-like body having a multilayer structure may be used. In addition, when the material of the lens part 52 and the protruding item | line part 55 is the same as the main-body part 51, the light-guide plate 50 can be made into the plate-shaped body comprised with the single translucent material.

  Further, when a translucent resin material is used as the translucent material constituting the main body 51, the lens unit 52, and the ridges 55, an ultraviolet absorber, an antistatic agent, an antioxidant, Additives such as processing stabilizers, flame retardants, and lubricants can also be added. These additives can be used alone or in combination of two or more. Note that it is preferable that an ultraviolet absorber is added to the light guide plate 50 because deterioration of the light guide plate 50 due to ultraviolet rays can be prevented when the light output from the light source unit 60 contains a lot of ultraviolet rays.

  Examples of UV absorbers include benzotriazole UV absorbers, benzophenone UV absorbers, cyanoacrylate UV absorbers, malonic ester UV absorbers, oxalic anilide UV absorbers, and triazine UV absorbers. Preferred are benzotriazole ultraviolet absorbers and triazine ultraviolet absorbers.

  The translucent resin material is usually used without adding a light diffusing agent as an additive, but may be added with a light diffusing agent as long as it is a slight amount that does not depart from the spirit of the present invention.

  The light diffusing agent is usually refracted from the light guide plate 50, specifically, the above-described translucent material (or transparent material) mainly constituting the main body 51, the lens 52, and the convex strip 55. Powders having different rates are used, which are dispersed in a light-transmitting material. As such a light diffusing agent, for example, organic particles such as styrene resin particles and methacrylic resin particles, and inorganic particles such as potassium carbonate particles and silica particles are used, and the particle diameter is usually 0.8 μm to 50 μm.

  The light guide plate 50 including the lens portion 52 and the convex strip portion 55 can be manufactured by ink jet printing (ink jet method), photopolymer method, extrusion molding, injection molding, or the like.

  When the light guide plate 50 is manufactured by using ink jet printing (ink jet method) or a photopolymer method, an ultraviolet curable resin can be used as a material for the lens portion 52 and the convex strip portion 55. An acrylic ultraviolet curable resin can be used.

  An example of a manufacturing method of the light guide plate 50 when the material of the lens part 52 is made of an acrylic ultraviolet curable resin and the inkjet method is used will be described. In this case, first, the main body 51 as a plate-like body having the ridges 55 on the emission surface 51a side is formed by extrusion molding or injection molding. Next, an ultraviolet curable resin is dropped (printed) on the surface to be the back surface 51b of the main body 51 formed in this way while operating the ink jet head. Next, the lens unit 52 is formed by irradiating the ultraviolet curable resin with ultraviolet rays and curing the resin.

  When the inkjet method is employed for forming the lens portion 52, an original plate or the like essential for screen printing, which is an example of another printing method, becomes unnecessary. The plurality of lens portions 52 are usually arranged in a predetermined dot pattern so that the luminance of light emitted from the emission surface 51a is increased by appropriately repeating the design process and the trial production process. In the ink jet method having no original plate, the time required for determining the predetermined dot pattern can be shortened. As a result, the light guide plate 50 can be manufactured more efficiently.

Next, the shape of the lens formed when the lens portion 52 is printed by the inkjet method will be described. Here, a lens when formed under the following conditions while changing the number of times of ink dropped to form one lens portion 52 (number of drops) and the liquid repellent treatment applied to the back surface of the main body portion 51. The shape of the part 52 was observed.
Condition 1: Printing with a fixed number of drops on the surface with the liquid repellent coating Condition 2: Printing with the number of drops being changed on the surface with the liquid repellent coating Condition 3: Fluorine plasma treatment is applied Printing on the printed surface while changing the number of drops

The lens portions 52 printed under the above conditions 1 to 3 were observed, and the aspect ratio [h _IIa / w _IIa ] and the sharpening method k _IIa were calculated. The calculation results from this observation are shown in FIGS. FIG. 12 summarizes the calculation results from the observations of FIGS. 11A to 11C in one table. Based on the distribution of the aspect ratio [h _IIa / w _IIa ] and the sharpening method k _IIa shown in FIG. 12, the shape of the lens portion 52 printed by the ink jet method is the aspect ratio shown in the frame shown in FIG. h _IIa / w _IIa ] and the point k k _IIa .

Further, it is possible to obtain the calculation result of the observation, kurtosis how _{k a} and aspect ratio relationship between _{[h IIa / w} IIa] curvature for the lens shape and width defined by the radius _[r II _{/ w IIa],} and the relationship between the bottom angle gamma _II for kurtosis how _{k a} and an aspect ratio _{[h IIa / w} IIa] lens shape and width defined by, respectively 13 and 14, shown in FIGS. 15 and 16. 13 and 15 show a range in which the sharpening method k _IIa is 0.1 or more and 0.9 or less. 14 and 16 show a range in which k _IIa is −0.9 or more and 0 or less. 13 to 16, hatched cells correspond to the lens shape defined by the aspect ratio [h _IIa / w _IIa ] and the sharpening method k _IIa in the frame in FIG.

  Based on FIGS. 12-16, the shape of the lens part 52 which can be printed by the inkjet method can be illustrated. Specifically, the shape of the lens portion 52 exemplified in the above embodiment, that is, the shape defined by any of the combinations in the chart shown in FIG. In other words, since the shape of the lens part 52 defined by any of the combinations in the chart shown in FIG. 9 can be printed by the ink jet method, the lens part 52 is formed on the main body part 51 of the light guide plate 50. In this case, it can be said that the shape can be easily formed.

Further, the outer shape of the lens portion 52 is a shape defined by a combination of the aspect ratio [h _IIa / w _IIa ], the radius of curvature [r _II / w _IIa ] and the bottom angle γ _II shown in the chart of FIG. In this range, when the contour line of the lens unit 52 is a conic curve expressed by the above formula (2), a condition of the parameter k _IIa indicating the _sharpness can be further added. Hereinafter, the conditions of the outer shape that the lens unit 52 satisfies for each aspect ratio [h _IIa / w _IIa ] shown in the chart of FIG. 17 will be specifically exemplified.

(1) When 0.07 ≦ h _IIa / w _IIa <0.09 The outer shape of the lens portion 52 is a shape that satisfies −0.15 ≦ k _IIa ≦ 0.45.
(2) When 0.09 ≦ h _IIa / w _IIa <0.11 The outer shape of the lens portion 52 is a shape satisfying −0.15 ≦ k _IIa ≦ 0.55.
(3) When 0.11 ≦ h _IIa / w _IIa <0.13 The outer shape of the lens portion 52 is a shape that satisfies −0.15 ≦ k _IIa ≦ 0.55.
(4) When 0.13 ≦ h _IIa / w _IIa <0.15 The outer shape of the lens portion 52 is a shape satisfying −0.65 ≦ k _IIa ≦ 0.55.
(5) When 0.15 ≦ h _IIa / w _IIa <0.17 The outer shape of the lens portion 52 is a shape satisfying −0.65 ≦ k _IIa ≦ 0.65.
(6) When 0.17 ≦ h _IIa / w _IIa <0.19 The outer shape of the lens portion 52 is a shape satisfying −0.65 ≦ k _IIa ≦ 0.65.

(7) When 0.19 ≦ h _IIa / w _IIa <0.21 The outer shape of the lens portion 52 is a shape satisfying −0.95 ≦ k _IIa ≦ 0.65.
(8) When 0.21 ≦ h _IIa / w _IIa <0.23 The outer shape of the lens portion 52 is a shape satisfying −0.95 ≦ k _IIa ≦ 0.45.
(9) When 0.23 ≦ h _IIa / w _IIa <0.25 The outer shape of the lens portion 52 is a shape satisfying −0.95 ≦ k _IIa ≦ 0.45.
(10) When 0.25 ≦ h _IIa / w _IIa <0.27 The outer shape of the lens portion 52 is a shape satisfying −0.95 ≦ k _IIa ≦ 0.05.
(11) In the case of 0.27 ≦ h _IIa / w _IIa <0.29 The outer shape of the lens portion 52 is a shape satisfying −0.75 ≦ k _IIa ≦ −0.55.
(12) When 0.29 ≦ h _IIa / w _IIa <0.31 The outer shape of the lens portion 52 is a shape satisfying −0.75 ≦ k _IIa ≦ −0.55.

  Here, the lens shape has been described as the lens portion 52 that can be printed by the ink jet method. However, as described above, the lens portion 52 having the lens shape can be formed by extrusion molding or injection molding other than the ink jet method. It can also be formed. In this case, the shape may be other than the range shown in the charts of FIGS.

  Moreover, the light guide plate 50 in which the lens portion 52 and the convex strip portion 55 are formed can be manufactured by extrusion molding, injection molding, or the like. In this case, the material of the lens portion 52 and the convex strip portion 55 is the same as the material of the main body portion 51. In addition, the light guide plate 50 on which the main body 51, the ridges 55, and the lens portions 52 as the plate-like body having the ridges 55 are formed, for example, cuts out a plate material made of a translucent material (or a transparent material). It can also be produced by a method.

  Next, the operation effect of the light guide plate 50 will be described by taking as an example a case where the light guide plate 50 is applied to the transmissive image display device 10 as a part of the surface light source device 30 as shown in FIG.

  When the point light source 61 included in the light source unit 60 emits light, the light from the point light source 61 enters the light guide plate 50 from the side surface 50 a of the light guide plate 50 facing the point light source 61. The light incident on the light guide plate 50 propagates while being totally reflected in the light guide plate 50. When light propagating in the light guide plate 50 enters the lens unit 52, the light is reflected in the lens unit 52 under conditions other than the total reflection condition. Therefore, the light reflected in the lens part 52 is emitted from the emission surface 51a. Since the protruding surface portion 55 is formed on the emission surface 51a, the light emission efficiency can be increased as compared with a light guide plate in which the protruding surface portion is not formed on the emission surface. The luminance is improved by these actions. In the transmissive image display device 10 of the present embodiment, since the transmissive image display unit 20 is provided on the light guide plate 50, the transmissive image display unit 20 is illuminated with light having higher luminance. As a result, the brightness of the image displayed on the transmissive image display unit 20 can be improved.

  Next, the point that the light emission efficiency of the light guide plate 50 in which the lens portion 52 and the convex strip portion 55 are formed is higher than that of the conventional light guide plate will be described based on the simulation result. However, the present invention is not limited to these simulations.

FIG. 18 is a schematic diagram showing a simulation model. For convenience of explanation, the components corresponding to the components shown in FIG. 1, described are denoted by the M as a light guide plate 50 _M. As shown in FIG. 18, the simulation is performed at a position facing the side surfaces 50 _M a (51 _M c) and 50 _M b (51 _M d) of the light guide plate 50 _M to be evaluated in detail later. In each of the models in which the point light sources 61 _M and 61 _M are arranged and the reflection sheet as the reflection portion 70 _M is arranged below the light guide plate 50 _M , the light emission efficiency E is calculated using the ray tracing method.

The simulation conditions are as follows.
Of - the light guide plate 50 _M constituent material: any body part 51 _M and the lens unit 52 _M has a convex portion 55 _M is PMMA (refractive index: 1.49) plan view shape (plate assumptions, the light guide plate 50 _M of (Shape seen from thickness direction): rectangle / light guide plate 50 _M long side length W1: 540 mm
· Light guide plate 50 _M , short side length W2: 20 mm
-Main body 51 _M thickness t: 3 mm
The distance between the lens portion 52 _M of the light guide plate 50 _M and the tip 52 _M a of the _M and the reflection portion 70 _M : 0.1 mm
Reflector 70 _M : Assuming reflection characteristics equivalent to those of the white reflector taken out from the backlight unit used in “KDL40EX7” manufactured by Sony Corporation. Wavelength of light emitted from the point light source 61 _M : 550 nm Assumption: Distance between point light source 61 _M and light guide plate 50 _M : 0.05 mm
Incidentally, assuming periodic boundary conditions in the body portion 51 side 51 of _{M M} e and side 51 _M f. That was a return to all light in the side surface 51 _M e and 51 _M f is reflected guided plate 50 _M. Thus, by providing periodic boundary conditions in the short-side direction of the light guide plate 50 _M (Y axis direction), the length of the short side direction is the simulation that assumes a substantially infinite light guide plate It will be.

Under such conditions, the light output efficiency by calculating the ratio of the amount E _o of all of the light emitted from the emitting surface 51 M _a relative amount E _i of light incident on the subject to the light guide plate 50 _M rating E (= E _o / E _i ) was obtained.

Next, the subject to the light guide plate 50 _M of the evaluation will be described. The evaluation and the light guide plate 50 made _M, emitting surface 51 M _a side of 12 kinds of the light guide plate 50 in shape and back 51 case 1 to case 12 and M _b side of the shape is a combination shown in Table 1 below _M is assumed.

<Outgoing surface 51 _Ma side>
The light guide plate 50 _M of cases 1 6, the exit surface 51 M _a side, assuming those lenticular lenses 55 _M as convex portions are formed. Specifically, as shown in FIG. 18, it is assumed that a lenticular lens 55 _M which are adjacent to the short side direction are arranged with a predetermined spacing. Here, the width _{w Ia} of the lenticular lens 55 _M 475, the distance S of the lenticular lens 55 _M between 25 [mu] m, the coverage of a plurality of lenticular lenses 55 _M at the exit plane 51 _M a of the main body portion 51 _M 95% did.

The light guide plate 50 _M Case 7 Case 9, the emission surface 51 _M a side, to form a prism 55 _M as ridges. Specifically, the prism 55 _M shown in FIG. 7 in place of the lenticular lens 55 _M in FIG. 18, the prism 55 _M which are adjacent to the short side direction is assumed to be disposed with no gap. Here, setting the width _{w Ia} of the prism 55 _M 500 [mu] m, an interval S of the prism 55 _M between 0 .mu.m, the coverage of a plurality of prisms 55 _M at the exit plane 51 _M a of the main body portion 51 _M to 100%.

When the cross-sectional shapes of the lenticular lens 55 _M and the prism 55 _M are defined as a conic curve represented by the following formula (3), it is assumed that the aspect ratio h _Ia / w _Ia and the sharpening method k _Ia are shown in Table 1, respectively. .

On the other hand, the case 10 case 12 exit face 51 _M a side of the light guide plate 50 _M of the lenticular lens 55 _M or prisms 55 _M is not formed as a convex portion, emitting surface 51 _M a is substantially flat We assumed what is.

<Back 51 _M b side>
The cases 1 to 12 rear 51 _M b side of the light guide plate 50 _M of were arranged microlenses 52 _M as a lens unit at regular intervals. Specifically, setting the square grid in which a plurality of square are arrayed to the back 51 M _b, it was placed one lens portion 52 _M to each square, which is a constituent unit of a square lattice. The micro lens 52 _M as a plurality of lenticular lenses 55 _M are arranged at a coverage rate of 100% on the exit surface 51 M _a side, optimized coverage as the emission light intensity uniformity is more than 95% Arranged in distribution. Figure 19 is an example of a coverage distribution of the micro lenses 52 _M in cases 1 6, the horizontal axis represents the distance (mm) from the center of the light guide plate 50 _M, the vertical axis coverage (%) Is shown. Figure 20 is an example of a coverage distribution of the micro lenses 52 _M in the case 7 to the case 12, the horizontal axis represents the distance (mm) from the center of the light guide plate 50 _M, the vertical axis coverage (%) Is shown. According to FIG 19 and FIG 20, in any case, the coverage of the one microlens 52 _M for a square lattice in the X-axis-direction center portion of the rear 51 _M b has a 74.61%.

When the cross-sectional shape of the micro lens 52 _M is defined as a conic curve represented by the following formula (4), the aspect ratio h _IIa / w _IIa and the sharpening method k _IIa are shown in Table 1, respectively.

It will now be described in detail the point light sources 61 _M. Two point light sources 61 _M and 61 _M are arranged in the short-side direction of the light guide plate 50 _M , the distance L1 from each end is 5 mm, and the distance between the light sources L2 is 10 mm. The point light source 61 _M is a surface light source having a length of 5.5 mm in the horizontal direction (depth direction) and a length of 2 mm in the vertical direction (thickness direction of the light guide plate).

Figure 21 is a view showing an example of the directional characteristics of the point light source 61 _M (light distribution characteristics). The horizontal axis in FIG. 21 indicates the outgoing angle θ (°), and the vertical axis indicates the normalized outgoing light intensity normalized by the maximum outgoing light intensity. In the present embodiment, θ = 0 corresponds to the X-axis direction in FIG. The point light source 61 _M is a so-called Lambertian light source, and a light emitting diode is an example of the point light source 61 _M. The Lambertian type light source has a maximum output light intensity at which the output light intensity is maximum, and the output angle is around 0 ° (front direction), and decreases substantially monotonically as the inclination from the front direction (output angle) increases. It has the feature of going. PD in FIG. 21 indicates the directivity characteristic in the case of theoretical perfect diffusion. In this simulation, a light source capable of obtaining this characteristic is assumed.

For each of the light guide plate 50 _M of cases 1 12 shows the results of the simulation in the table of FIG. 22. In the chart of FIG. 22, the numerical value in the column showing each simulation result indicates the light emission efficiency E (%).

Light output efficiency E of each of the light guide plate 50 _M of the emission surface 51 _M a of the ridge portion side lenticular lens 55 _M or cases 1 9 the prism 55 _M is formed, the emission surface 51 _M a side higher than the light output efficiency E of the lenticular lens 55 _M or prisms 55 each of the light guide plate 50 of _M is not the case 10 to the case 12 _M as ridges could be confirmed. Thus, by forming the convex portion such as the lenticular lens 55 _M or prism 55 _M on the exit surface 51 M _a side, the light output efficiency E is enhanced. That is, the higher the light guide plate 50 _M of output efficiency by using the surface light source device, it was confirmed that it is possible to improve the luminance.

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

In the above embodiment, the plurality of lens portions 52 formed on the back surface 51b have the aspect ratio [h _IIa / w _IIa ], the radius of curvature [r _II / w _IIa ] and the bottom angle γ _{II shown in FIG.} It was explained that the range of the shape defined by the combination can be made. However, at least half of the plurality of lens portions formed on the back surface 51b may be the lens portion 52 described in the above embodiment. In other words, among the plurality of lens portions formed on the back surface 51b, half of the first lens portion as the lens portion 52 and the other half do not satisfy the conditions described in the above embodiment. You may comprise from a lens part. The ratio of the number of first lens portions as the lens portions 52 to the number of the second lens portions may be 6: 4.

Further, as illustrated in FIG. 8, the shape of the lens unit 52 has a shape in which the angle formed between the tangential plane of the lens unit 52 and the back surface 51 b monotonously decreases from the bottom side of the lens unit 52 to the tip side. It is preferable. However, if the lens unit 52 has a shape defined by a combination represented by h _IIa / w _IIa , r _II / w _IIa and γ _II shown in the chart of FIG. It does not have to be monotonously decreasing toward the tip 52a side with respect to the angle formed by the back surface 51b.

  Furthermore, the arrangement position of the light source unit 60 is not limited to two places. For example, the light source part 60 can also be arrange | positioned at one place. In this case, the light source unit 60 is disposed on one of the side surface 51c and the side surface 51d shown in FIG. A reflective tape such as a mirror tape or a white diffusion tape for preventing light leakage may be attached to the other side surface opposite to the one side surface on which light from the light source unit 60 is incident.

  Further, in the above simulation, an example of the point light source 61 having directivity characteristics in the case of theoretical complete diffusion is shown, but the surface light source device 30 and the transmissive image display device 10 of the present embodiment are limited to this. It is not something. For example, as shown in FIG. 21, a curve PD1 that deviates by -0.6% when the emission angle is 30 ° and -11.0% when the emission angle is 60 ° with respect to the directivity characteristic PD indicating complete diffusion. (Shown by a dotted line in FIG. 21) and a curve PD2 (shown by a broken line in FIG. 21) deviating by 6.9% when the emission angle is 30 ° and by 16.4% when the emission angle is 60 °. Any point light source having a Lambertian directivity that satisfies the emission angle of the region and the normalized radiation intensity may be used.

In the above embodiment, as an example of the outer shape of the convex portion 55, (I) Aspect ratio [h _{Ia /} w _Ia], (II) the radius of curvature to the width [r _{I /} w _Ia] and (III) the bottom An example of the outer shape that can be specified by the angle γ _I has been described. In addition to this condition, it has also been explained that the contour line of the ridge 55 can be defined as a conical curve represented by the following formula (5). However, the present invention is not limited to this.

ただし、式（６）において、ｖ_Ｉ０（ｕ_Ｉ）は、

を満たす。式（７）は、上記式（１）と同様、ｗ_Ｉaは凸条部５５のｕ_Ｉ軸方向の長さであり、ｈ_Ｉaは凸条部５５をｖ_Ｉ０（ｕ_Ｉ）で示される形状とした場合における凸条部５５の両端部５５ｂ，５５ｂ間における最大高さに対応する。ｋ_Ｉaは凸条部５５の先端部５５ａのとがり方を示すパラメータである。例えばとがり方ｋ_Ｉａが０のとき、凸条部５５の外形は放物線形状となり、とがり方ｋ_Ｉａが１のとき、凸条部５５の外形はプリズム形状となり、とがり方ｋ_Ｉａが−１のとき、凸条部５５の外形は楕円を半分に切った形状となる。 For example, when the u _I v _I coordinate system is set on the cross section perpendicular to the extending direction of the ridge 55 (the u _I axis direction is set to the X axis direction and the v _I axis direction is set to the Z axis direction), the ridge portion The cross-sectional shape of 55 can also be represented by v _I (u _I ) that satisfies the following formula (6).

However, in equation (6), v _I0 (u _I ) is

Meet. In Formula (7), w _Ia is the length of the ridge portion 55 in the u _I axis direction, and h _Ia is a shape indicated by v _I0 (u _I ) of the ridge portion 55 in the same manner as Equation (1). This corresponds to the maximum height between both end portions 55b and 55b of the ridge 55 in the case of the above. k _Ia is a parameter indicating how the tip 55a of the ridge 55 is sharpened. For example, when the sharpening method k _Ia is 0, the outer shape of the ridge 55 is a parabolic shape, when the sharpening method k _Ia is 1, the outer shape of the ridge 55 is a prism shape, and when the sharpening method k _Ia is −1. The outer shape of the ridge portion 55 is a shape obtained by cutting an ellipse in half.

Moreover, in this invention, you may form so that the external shape of the protruding item | line part 55 provided in an output surface side may turn into the outer shape of the protruding item | line part 155 shown below. That is, in the cross section orthogonal to the extending direction of each of the plurality of ridge portions 155, the length along the contour line from the apex (tip portion) 155a in the cross section of the ridge portion 155 to the point P on the contour line. Is L, the axis passing through both ends of the ridge 155 is the u axis, and the slope (absolute value) of the cross-sectional shape of the ridge 155 at the point P with respect to the u axis is α,
In the range of −0.20 <L <0.20, the following formulas (8) and (9) are satisfied,
0 <α (8)
150 ≦ Δα / ΔL <260 (9)
In the range of −0.65 <L ≦ −0.20 and 0.20 ≦ L <0.65, the following formulas (10) and (11) are satisfied,
0 ≦ α (10)
0 ≦ Δα / ΔL <30 (11)
In the range of -1.00 <L ≦ −0.65 and the range of 0.65 ≦ L <1.00, the shape may satisfy the following formulas (12) and (13).
0 <α (12)
5 ≦ Δα / ΔL <75 (13)

  In the light guide plate in which a plurality of convex strips 155 having a cross-sectional shape where α and Δα / ΔL satisfy the above conditions are formed on the light exit surface, the light incident on the light incident surface of the light guide plate is It is easy to propagate in the extending direction of 155. Therefore, when light propagates through the light guide plate from the light incident position, the spread of the light is suppressed, so that crosstalk can be reduced. Note that L is 0 at the center in the u-axis direction, and increases as it goes from the center to the right (L> 0), and decreases as it goes from the center to the left (L <0).

The outer shape of the ridge 155 preferably satisfies the following formula (14) in the range of −0.20 <L <0.20.
170 ≦ Δα / ΔL <240 (14)

The outer shape of the ridge portion 155 preferably satisfies the following formula (15) in the range of −0.65 <L ≦ −0.20 and 0.20 ≦ L <0.65.
0 ≦ Δα / ΔL <20 (15)

The outer shape of the ridge portion 155 preferably satisfies the following formula (16) in the range of −1.00 <L ≦ −0.65 and the range of 0.65 ≦ L <1.00.
10 ≦ Δα / ΔL <60 (16)

The outer shape of the convex portion 155, the width of the convex portion 155 and _{w a,} when the maximum height of the convex portions 155 was set to _{h a,} the aspect ratio of the convex portion 155 _{(h a} / _w a) is , 0.3 or more and less than 0.5 is preferable.

  Embodiment A1-A5 which is an example of the external shape of such a protruding item | line part 155 is demonstrated using FIGS. 23-27. 23 to 27 are drawings showing examples of cross-sectional shapes orthogonal to the extending direction of the ridges. FIG. 23 shows Embodiment A1, FIG. 24 shows Embodiment A2, FIG. 25 shows Embodiment A3, FIG. 26 shows Embodiment A4, and FIG. 27 shows Embodiment A5. 23 to 27, the uv coordinate system is set with the u-axis as the direction orthogonal to the extending direction of the ridges 155. In this uv coordinate system, the cross-sectional shape of the ridge portion 155 has both end portions 155b and 155b on the u-axis. In the uv coordinate system, the v-axis passes through the center between both ends 155b and 155b on the u-axis. In the form shown in FIGS. 1 and 2, the u-axis direction is the Y-axis direction. The v-axis direction is the Z-axis direction.

  In the uv coordinate system, the cross-sectional shape of the ridge portion 155 satisfies the following equations (17) to (22). However, the position of the ridge 155 in the u-axis direction is w, and the inclination of the cross-sectional shape of the ridge 155 at the position w with respect to the u-axis is α. In the cross section orthogonal to the extending direction of the ridge portion 155, the length along the contour line from the vertex 155a to the point P on the contour line in the cross section of the ridge portion 155 is L. The position of the point P in the u-axis direction is the position w described above, and the inclination α (absolute value) is the inclination at the point P. Δα / ΔL is the ratio of the change amount of α to the change amount of L. The inclination α is the smaller angle (0 ≦ α ≦ 90) among the angles at which the tangent of the cross-sectional shape of the ridge 155 at the position w (point P) and the u axis intersect.

In the u-axis direction, the length from the center O (0, 0) of the ridge 155 to the end 155b is 1. The position of the end portion 155b of the ridge portion 155 is w = -1,1. The position w increases toward the right from the center O (w> 0), and decreases toward the left from the center O (w <0). Further, in the v-axis direction, and a height corresponding to the length of the end portion 155b from the center O of the convex portion 155 as a h _a. Position w is the normalized value width w _a of the convex portion 155 is a value representing a position in a ratio to the width w _a.

The cross-sectional shape of the ridge portion 155 satisfies the following expressions (17) and (18) in the first section A (a range of −0.20 <L <0.20).
0 <α (17)
150 ≦ Δα / ΔL <260 (18)

  In the first section A, the slope α of the cross-sectional shape of the ridge portion 155 increases. In other words, the inclination α increases as the distance from the center O increases.

The cross-sectional shape of the ridge 155 is expressed by the following formulas (19) and (19) in the second section B (the range of −0.65 <L ≦ −0.20 and the range of 0.20 ≦ L <0.65). 20) is satisfied.
0 ≦ α (19)
0 ≦ Δα / ΔL <30 (20)

  In the second section B, the inclination α increases or does not change in the cross-sectional shape of the ridge portion 155. In other words, as the distance from the center O increases, the inclination α increases or is constant.

The cross-sectional shape of the ridge 155 is expressed by the following formulas (21) and (3) in the third section C (the range of −1.00 <L ≦ −0.65 and the range of 0.65 ≦ L <1.00). 22) is satisfied.
0 <α (21)
5 ≦ Δα / ΔL <75 (22)

  In the third section C, the slope α of the cross-sectional shape of the ridge portion 155 increases. In other words, the inclination α increases as the distance from the center O increases.

In the first section A, Δα / ΔL may satisfy the following formula (23).
170 ≦ Δα / ΔL <240 (23)

In the second section B, Δα / ΔL may satisfy the following formula (24).
0 ≦ Δα / ΔL <20 (24)

In the third section C, Δα / ΔL may satisfy the following formula (25).
10 ≦ Δα / ΔL <60 (25)

FIG. 28 is a drawing showing a cross-sectional portion of the ridge portion 155. When two arbitrary points on the outer shape of the ridge 155 are P ₁ and P ₂ , ΔL = L ₂ −L ₁ (where L ₂ > L ₁ ) and Δα = α ₂ −α ₁ (where , Α ₂ ≧ α ₁ ). However, L ₁ is the position of the point P ₁ on the contour line, and α ₁ is the inclination (intersection angle with the u axis) at the point P ₁ . Similarly, L ₂ is the position of the point P ₂ on the contour line, and α ₂ is the inclination (intersection angle with the u axis) at the point P ₂ .

  29 to 31 are diagrams showing the relationship between the position L on the contour line of the cross-sectional shape of the ridge 155 and the inclination angle α. 29 to 31, the horizontal axis indicates the position L, and the vertical axis indicates the inclination angle α [deg]. In the horizontal axis, L = 0 indicates the center on the contour line of the ridge portion 155. The cross-sectional shape of the ridge portion 155 is such that when L = 0, it forms the apex (tip portion 155a) of the ridge portion 155 and the inclination angle α = 0. The position L is indicated by a ratio with the position of the end 155b in the width direction (u-axis direction) of the ridge 155 being L = 1. L = 0.5 indicates an intermediate position between the center O and the end portion 155b. 29 to 31 show the inclination angle α when L is in the range of 0 ≦ L ≦ 1, but the value of the inclination angle α when L is in the range of −1 ≦ L ≦ 0 is 0 ≦ L. It is a folded value with a value of L ≦ 1.

  29A shows the embodiment A1, FIG. 29B shows the embodiment A2, FIG. 30A shows the embodiment A3, FIG. 30B shows the embodiment A4, and FIG. 31 shows the embodiment A5. . As for the cross-sectional shape of the protruding item | line part 155 which concerns on embodiment A1-A5, in the 1st area A, the inclination | tilt angle (alpha) is increasing. That is, as the distance from the center O toward the end 155b (L = 1) is increased, the inclination angle α is increased.

  In the second section B, the cross-sectional shape of the ridge portion 155 according to the embodiment A1 increases or does not change in the second section B. Specifically, the cross-sectional shape of the ridge portion 155 according to Embodiment A1 is constant without changing the inclination angle α in the range of 0.20 ≦ L <0.60. In the cross-sectional shape of the ridge portion 155 according to Embodiment A1, the inclination angle α increases in the range of 0.60 ≦ L <0.65.

  As for the cross-sectional shape of the protruding item | line part 155 which concerns on embodiment A2-A5, in the 2nd area B, inclination-angle (alpha) is increasing. That is, as the distance from the center O toward the end 155b (L = 1) is increased, the inclination angle α is increased.

  As for the cross-sectional shape of the protruding item | line part 155 which concerns on embodiment A1-A5, in the 3rd area C, inclination-angle (alpha) is increasing. That is, as the distance from the center O toward the end 155b (L = 1) is increased, the inclination angle α is increased.

  FIG. 32 is a diagram showing the relationship between the line segment length L of the cross-sectional shape of the ridge 155 and Δα / ΔL. In FIG. 32, the horizontal axis represents the line segment length L, and the vertical axis represents Δα / ΔL. FIG. 32 shows Δα / ΔL when L is in the range of 0 ≦ L ≦ 1, but Δα / ΔL when L is in the range of −1 ≦ L ≦ 0 is 0 ≦ L ≦ 1. It becomes the wrapping value of the value of. The line segment length L here is shown as a ratio when the length along the contour line from the apex (tip portion) 155a to the end portion 155b is “1”.

  In the first section A, Δα / ΔL is 150 or more and less than 260 in the cross-sectional shape of the ridge portion 155 according to Embodiments A1 to A5. Regarding the cross-sectional shape of the ridge portion 155 according to the embodiments A1 to A5, Δα / ΔL is 0 or more and less than 30 in the second section B. In the third section C, Δα / ΔL is 5 or more and less than 75 in the cross-sectional shape of the ridge portion 155 according to Embodiments A1 to A5.

(aspect ratio)
width w _a of the u-axis direction of the convex portion 155 is generally smaller than the distance between the light source 61 adjacent points. Examples of the width w _a are 50 μm to 2000 μm, preferably 100 μm to 1000 μm, and more preferably 200 μm to 800 μm. h _a is both end portions 155b of the convex portion 155, corresponding to the maximum height between 155b. The aspect ratio of the convex portion 155 _(h a / _{w a)} is the ratio of the maximum height _{h a} to the width _{w a} of the convex portion 155. The aspect ratio of the ridge 155 is 0.3 or more and less than 0.5.

  The cross-sectional shape of the plurality of ridges 155 is substantially the same between the ridges 155. However, the cross-sectional shape of each of the plurality of ridge portions 155 may be different as long as the cross-sectional shape satisfies the above formulas (17) to (22).

  The light guide plate having the ridges 155 having the above-described configuration is not limited to a single layer structure, and may have a multilayer structure. In the present embodiment, the thickness of the light guide plate having the ridges 155 is the thickness of the main body. The plate | board thickness of a main-body part is the distance between the top part (tip part) 155a of the protruding item | line part 155, and the back surface in a main-body part, Usually, 0.5 mm-8 mm, Preferably, it is 1 mm-6 mm, More preferably, it is 1.5 mm-4 mm.

Moreover, in this invention, you may form so that the external shape of the protruding item | line part 55 provided in the output surface side may turn into the outer shape of the protruding item | line part 255 shown below. That is, in the cross section orthogonal to the extending direction of each of the plurality of ridge portions 255, the length along the contour line from the apex (tip portion) 255a to the point P on the contour line in the cross section of the ridge portion 255. Is L, the axis passing through both ends of the ridge 255 is the u axis, and the inclination (absolute value) of the cross-sectional shape of the ridge 255 at the point P with respect to the u axis is α,
In the range of −0.20 <L <0.20, the following formulas (26) and (27) are satisfied,
0 <α (26)
60 ≦ Δα / ΔL <140 (27)
In the range of −0.65 <L ≦ −0.20 and 0.20 ≦ L <0.65, the following formulas (28) and (29) are satisfied,
0 ≦ α (28)
0 ≦ Δα / ΔL <30 (29)
In the range of −1.00 <L ≦ −0.65 and the range of 0.65 ≦ L <1.00, it may be formed to have a shape satisfying the following formulas (30) and (31).
0 <α (30)
10 ≦ Δα / ΔL <110 (31)

  In the light guide plate in which a plurality of convex strips 255 having a cross-sectional shape where α and Δα / ΔL satisfy the above conditions are formed on the light output surface, the light incident on the light incident surface of the light guide plate is It is easy to propagate in the extending direction of 255. Therefore, when light propagates through the light guide plate from the light incident position, the spread of the light is suppressed, so that crosstalk can be reduced. Note that L is 0 at the center in the u-axis direction, and increases as it goes from the center to the right (L> 0), and decreases as it goes from the center to the left (L <0).

It is preferable that the outer shape of the ridge portion 255 satisfies the following formula (32) in the range of −0.20 <L <0.20.
80 ≦ Δα / ΔL <120 (32)

It is preferable that the outer shape of the ridge 255 satisfies the following formula (33) in the range of −0.65 <L ≦ −0.20 and 0.20 ≦ L <0.65.
0 ≦ Δα / ΔL <20 (33)

It is preferable that the outer shape of the ridge portion 255 satisfies the following formula (34) in a range of −1.00 <L ≦ −0.65 and a range of 0.65 ≦ L <1.00.
30 ≦ Δα / ΔL <90 (34)

The outer shape of the convex portion 255, the width of the convex portion 255 and _{w a,} when the maximum height of the convex portions 255 was set to _{h a,} the aspect ratio of the convex portion 255 _{(h a} / _w a) is , Preferably 0.15 or more and less than 0.3.

  Embodiment B1-B5 which is an example of the external shape of such a protruding item | line part 255 is demonstrated using FIGS. 33-37. 33 to 37 are drawings showing examples of cross-sectional shapes orthogonal to the extending direction of the ridges. FIG. 33 shows Embodiment B1, FIG. 34 shows Embodiment B2, FIG. 35 shows Embodiment B3, FIG. 36 shows Embodiment B4, and FIG. 37 shows Embodiment B5. 33 to 37, the uv coordinate system is set with the u-axis as the direction orthogonal to the extending direction of the ridges 255. In this uv coordinate system, the cross-sectional shape of the ridge portion 255 has both end portions 255b and 255b on the u-axis. In the uv coordinate system, the v-axis passes through the center between both end portions 255b and 255b on the u-axis. In the form shown in FIGS. 1 and 2, the u-axis direction is the Y-axis direction. The v-axis direction is the Z-axis direction.

  In the uv coordinate system, the cross-sectional shape of the ridge 255 satisfies the following formulas (35) to (40). However, the position of the ridge portion 255 in the u-axis direction is w, and the inclination of the cross-sectional shape of the ridge portion 255 at the position w with respect to the u-axis is α. In the cross section orthogonal to the extending direction of the ridge portion 255, the length along the contour line from the vertex in the cross section of the ridge portion 255 to the point P on the contour line is L. Δα / ΔL is the ratio of the change amount of α to the change amount of L. The inclination α is the smaller angle (0 ≦ α ≦ 90) among the angles at which the tangent of the cross-sectional shape of the ridge portion 255 at the position w (point P) and the u axis intersect.

In the u-axis direction, the length from the center O (0, 0) of the ridge portion 255 to the end portion 255b is set to 1. The position of the end portion 255b of the ridge portion 255 is w = -1,1. The position w increases toward the right from the center O (w> 0), and decreases toward the left from the center O (w <0). Further, in the v-axis direction, and a height corresponding to the length of the end portion 255b from the center O of the convex portion 255 as a h _a. The position w is a value standardized by the width w _a of the ridge portion 255 and is a value expressing the position by _a ratio to the width w _a .

The cross-sectional shape of the ridge portion 255 satisfies the following expressions (35) and (36) in the first section A (a range of −0.20 <L <0.20).
0 <α (35)
60 ≦ Δα / ΔL <140 (36)

  In the first section A, the slope α of the cross-sectional shape of the ridge portion 255 increases. In other words, the inclination α increases as the distance from the center O increases.

The cross-sectional shape of the protruding portion 255 is expressed by the following formulas (37) and (2) in the second section B (the range of −0.65 <L ≦ −0.20 and the range of 0.20 ≦ L <0.65). 38) is satisfied.
0 ≦ α (37)
0 ≦ Δα / ΔL <30 (38)

  In the second section B, the slope α increases or does not change in the cross-sectional shape of the ridge portion 255. In other words, as the distance from the center O increases, the inclination α increases or is constant.

The cross-sectional shape of the ridges 255 is expressed by the following formulas (39) and (3) in the third section C (the range of −1.00 <L ≦ −0.65 and the range of 0.65 ≦ L <1.00). 40) is satisfied.
0 <α (39)
10 ≦ Δα / ΔL <110 (40)

  In the third section C, the slope α increases in the cross-sectional shape of the ridge portion 255. In other words, the inclination α increases as the distance from the center O increases.

In the first section A, Δα / ΔL may satisfy the following formula (41).
80 ≦ Δα / ΔL <120 (41)

In the second section B, Δα / ΔL may satisfy the following formula (42).
0 ≦ Δα / ΔL <20 (42)

In the third section C, Δα / ΔL may satisfy the following formula (43).
30 ≦ Δα / ΔL <90 (43)

FIG. 38 is a drawing showing a cross-sectional portion of the ridge portion 255. When two arbitrary points on the outer shape of the ridge 255 are P ₁ and P ₂ , ΔL = L ₂ −L ₁ (where L ₂ > L ₁ ) and Δα = α ₂ −α ₁ (where , Α ₂ ≧ α ₁ ). However, L ₁ is the position of the point P ₁ on the contour line, and α ₁ is the inclination (intersection angle with the u axis) at the point P ₁ . Similarly, L ₂ is the position of the point P ₂ on the contour line, and α ₂ is the inclination (intersection angle with the u axis) at the point P ₂ .

  39 to 41 are diagrams showing the relationship between the position L on the contour line of the cross-sectional shape of the ridge portion 255 and the inclination angle α. 39 to 41, the horizontal axis indicates the position L, and the vertical axis indicates the inclination angle α [deg]. On the horizontal axis, L = 0 indicates the center of the ridge 255 on the contour line. The cross-sectional shape of the ridge portion 255 is such that, when L = 0, the apex (tip portion 255a) of the ridge portion 255 is formed and the inclination angle α = 0. The position L is indicated by a ratio with the position of the end portion 255b in the width direction (u-axis direction) of the ridge portion 255 being L = 1. L = 0.5 indicates an intermediate position between the center O and the end portion 255b. 39 to 41 show the inclination angle α when L is in the range of 0 ≦ L ≦ 1, the value of the inclination angle α when L is in the range of −1 ≦ L ≦ 0 is 0 ≦ L. It is a folded value with a value of L ≦ 1.

  39A shows the embodiment B1, FIG. 39B shows the embodiment B2, FIG. 40A shows the embodiment B3, FIG. 40B shows the embodiment B4, and FIG. 41 shows the embodiment B5. . In the first section A, the cross-sectional shape of the ridges 255 according to the embodiments B1 to B5 is increased in the inclination angle α. That is, as the distance from the center O toward the end 255b (L = 1) is increased, the inclination angle α is increased.

  In the second section B, the inclination angle α increases or does not change in the cross-sectional shape of the ridge portion 255 according to Embodiment B1. Specifically, the cross-sectional shape of the ridge portion 255 according to Embodiment B1 is constant without changing the inclination angle α in the range of 0.20 ≦ L <0.60. In the cross-sectional shape of the ridge portion 255 according to Embodiment B1, the inclination angle α is increased in the range of 0.60 ≦ L <0.65.

  As for the cross-sectional shape of the protruding item | line part 255 which concerns on embodiment B2-B5, in the 2nd area B, the inclination | tilt angle (alpha) has increased. That is, as the distance from the center O toward the end 255b (L = 1) is increased, the inclination angle α is increased.

  As for the cross-sectional shape of the protruding line part 255 according to the embodiments B1 to B5, the inclination angle α is increased in the third section C. That is, as the distance from the center O toward the end 255b (L = 1) is increased, the inclination angle α is increased.

  FIG. 42 is a diagram illustrating the relationship between the line segment length L of the cross-sectional shape of the ridge 255 and Δα / ΔL. In FIG. 42, the horizontal axis indicates the line segment length L, and the vertical axis indicates Δα / ΔL. FIG. 42 shows Δα / ΔL when L is in the range of 0 ≦ L ≦ 1, but Δα / ΔL when L is in the range of −1 ≦ L ≦ 0 is 0 ≦ L ≦ 1. It becomes the wrapping value of the value of. Here, the line segment length L is shown as a ratio when the length along the contour line from the apex (tip portion) 255a to the end portion 255b is “1”.

  In the first section A, Δα / ΔL is 60 or more and less than 160 in the cross-sectional shape of the ridge portion 255 according to Embodiments B1 to B5. Regarding the cross-sectional shape of the ridges 255 according to Embodiments B1 to B5, Δα / ΔL is 0 or more and less than 30 in the second section B. Regarding the cross-sectional shape of the ridges 255 according to the embodiments B1 to B5, Δα / ΔL is 10 or more and less than 110 in the third section C.

(aspect ratio)
The width w _a of the convex strip 255 in the u-axis direction is usually smaller than the distance between the adjacent point light sources 61. Examples of the width w _a are 50 μm to 2000 μm, preferably 100 μm to 1000 μm, and more preferably 200 μm to 800 μm. h _a is both end portions 255b of the convex portion 255, corresponding to the maximum height between 255b. The aspect ratio of the convex portion 255 _(h a / _{w a)} is the ratio of the maximum height _{h a} to the width _{w a} of the convex portion 255. The aspect ratio of the ridge 255 is 0.15 or more and less than 0.30.

  The cross-sectional shape of the plurality of ridges 255 is substantially the same between the ridges 255. However, the cross-sectional shape of each of the plurality of ridge portions 255 may be different as long as the cross-sectional shape satisfies the above formulas (35) to (40).

  The light guide plate having the ridges 255 having the above-described configuration is not limited to a single layer structure, and may have a multilayer structure. In the present embodiment, the thickness of the light guide plate having the ridges 255 is the thickness of the main body. The plate | board thickness of a main-body part is the distance between the top part (tip part) 255a of the protruding item | line part 255, and the back surface in a main-body part, Usually, 0.5 mm-8 mm, Preferably, it is 1 mm-6 mm, More preferably, it is 1.5 mm-4 mm.

  Moreover, although the said embodiment demonstrated the light-guide plate 50 integrally formed including the protruding item | line part 55, the light-guide plate of this invention is not limited to this. For example, by using a photopolymer method, the ridge 55 which is a portion above the reference surface 51g may be formed on the plate-like main body portion which is a portion below the reference surface 51g shown in FIG. .

  Further, in the transmissive image display device 10 shown in FIG. 1, other optical members may be disposed between the light guide plate 50 and the transmissive image display unit 20 without departing from the spirit of the present invention. it can. Examples of other optical members provided between the light guide plate 50 and the transmissive image display unit 20 include a reflective polarization separation sheet, a light diffusion sheet, a microlens sheet, a lenticular lens sheet, and a prism sheet.

  DESCRIPTION OF SYMBOLS 10 ... Transmission type image display apparatus, 20 ... Transmission type image display part, 21 ... Liquid crystal cell, 22, 23 ... Polarizing plate, 30 ... Surface light source device, 50 ... Light guide plate, 50a, 50b ... Side, 51 ... Main part, 51a: Emission surface (first surface), 51b ... Back surface (second surface), 51c, 51d ... Side surface (incident surface), 52 ... Lens portion, 52a ... Tip portion, 52b ... Bottom portion, 55, 155, 255 ... ridge (lenticular lens), 60 ... light source, 61 ... point light source, 70 ... reflector.

Claims (4)

A first surface extending in one direction and formed with a plurality of protruding strips arranged in parallel in a direction substantially orthogonal to the one direction, and a second surface opposite to the first surface And a plate-like main body portion having a plane intersecting the first and second planes, and an incident plane on which light is incident,
A plurality of lens portions that are formed on the second surface of the main body portion and are convex on the opposite side of the first surface when viewed from the second surface;
A light guide plate comprising: The ridge is a lenticular lens or a prism,
The light guide plate according to claim 1. The light guide plate according to claim 1 or 2,
A light source section that is disposed to face the incident surface of the light guide plate, and that supplies light to the incident surface;
A surface light source device. The light guide plate according to claim 1 or 2,
A light source section that is disposed to face the incident surface of the light guide plate, and that supplies light to the incident surface;
A transmission-type image display unit that is provided on the first surface side of the light guide plate and is illuminated by light emitted from the light guide plate;
A transmissive image display device.

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