JP2006108033A - Tandem type surface light source device - Google Patents

Tandem type surface light source device Download PDF

Info

Publication number
JP2006108033A
JP2006108033A JP2004296351A JP2004296351A JP2006108033A JP 2006108033 A JP2006108033 A JP 2006108033A JP 2004296351 A JP2004296351 A JP 2004296351A JP 2004296351 A JP2004296351 A JP 2004296351A JP 2006108033 A JP2006108033 A JP 2006108033A
Authority
JP
Japan
Prior art keywords
light
surface
refractive index
light source
prism
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP2004296351A
Other languages
Japanese (ja)
Inventor
Tomoyoshi Yamashita
友義 山下
Original Assignee
Mitsubishi Rayon Co Ltd
三菱レイヨン株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mitsubishi Rayon Co Ltd, 三菱レイヨン株式会社 filed Critical Mitsubishi Rayon Co Ltd
Priority to JP2004296351A priority Critical patent/JP2006108033A/en
Publication of JP2006108033A publication Critical patent/JP2006108033A/en
Application status is Pending legal-status Critical

Links

Images

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tandem type surface light source device having high luminance in a required range in the normal line direction of an entire light emission surface and its vicinity in the luminance distribution of a light emitting surface, and capable of enhancing the quality of a display image by a display device when using it as a backlight for the display device. <P>SOLUTION: A plurality of surface light emitting units are arranged in parallel with one another. Each surface light emitting unit U2 has a plate-like light guide body 3 having a refractive index ng. A light leakage modulator 8 on the rear side 34 of the light guide body is formed with a composite layer 80 having first and second refraction index regions 81, 82 with refraction indexes n1, n2 (ng>n1, n2>n1), and a third refraction index layer 83 with a refraction index n3 (n3>n1). In each of a plurality of prism columns 9 formed on the surface of the light leakage modulator 8, the inclination of a prism face 91 on the side closer to a primary light source 1 is 80-105° with respect to the light emission surface 33 of the light guide body, and the inclination of a prism face 92 on the side further away from the primary light source 1 is 35-55° with respect to the light emission surface 33 of the light guide body. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an edge light type surface light source device, and in particular, a surface with high brightness even in a large area by arranging a plurality of edge light type surface light emitting units having a primary light source and a light guide. The present invention relates to a surface light source device called a tandem type capable of emitting light.

  The tandem surface light source device of the present invention is suitable for a backlight of a large liquid crystal display device, for example.

  In recent years, liquid crystal display devices have been widely used as monitors for portable notebook computers or the like, as display units for liquid crystal televisions and video-integrated liquid crystal televisions, and in various other fields. The liquid crystal display device basically includes a backlight unit and a liquid crystal display element unit. Since the liquid crystal display device is required to be thin and compact, an edge light type that can be thin is often used as the backlight unit in order to satisfy this demand. Conventionally, as an edge light type backlight, at least one end face of a rectangular plate-shaped light guide is used as a light incident end face, and a linear or rod-like shape such as a straight tube fluorescent lamp is provided along the light incident end face. A primary light source is disposed, light emitted from the primary light source is incident on the light incident end face of the light guide and introduced into the light guide, and is one of the two main surfaces of the light guide. What is emitted from the light exit surface is widely used.

In recent years, there has been a demand for an increase in the size and brightness of a display screen of a liquid crystal display device, and a surface light source device called a tandem type has been proposed to meet this requirement. The tandem surface light source device is described in, for example, Japanese Patent Application Laid-Open No. 11-288611 (Patent Document 1). As described in Patent Document 1, the tandem surface light source device guides light emitted from the primary light source, the primary light source, and the light incident end face on which the light emitted from the primary light source enters and the light. A plurality of light guide blocks having a plate-like light guide body having a light exit surface from which light is emitted. This light guide block is closely arranged in parallel so that the light incident end faces of the light guide are in the same direction and a substantially continuous overall light exit surface is formed by the light exit surfaces of the light guide. Has been. In addition, a prism sheet is disposed on an arrangement of a plurality of light guide blocks (that is, on the entire emission surface). The prism sheet is provided with a plurality of prism rows extending substantially in parallel with the light incident end face of the light guide on the inner side (that is, the side facing the entire emission surface), and thereby the direction of light emitted from the entire emission surface. Is corrected in the normal direction of the entire exit surface within a cross section orthogonal to both the light incident end face and the light exit surface of the light guide. The prism sheet further includes a plurality of prism rows extending substantially perpendicular to the light incident end face of the light guide on the outer side thereof, whereby the direction of light emitted from the entire exit face is defined as the light guide light incident end face. Correction is made in the normal direction of the entire exit surface within the parallel cross section.
JP-A-11-288611

  By the way, in the tandem type surface light source device, the dimension in the direction along the light emitting surface of the light guide and substantially perpendicular to the light incident end surface (that is, the light incident on the light incident end surface is guided through the light guide. The direction dimension (width of each light guide block) tends to be reduced to, for example, 100 mm or less in order to improve luminance. In such a tandem surface light source device having a light guide block with a relatively short light guide direction length (that is, light guide length), light incident on the light guide is repeated by the light exit surface and the back surface on the opposite side. It is required to emit from the light exit surface with a small number of internal reflections.

  For this reason, the angle distribution of the light emitted from the light exit surface is such that the direction of the peak forms a larger angle with respect to the light guide light exit surface than that of the light guide having a long length. A part of the light incident on one prism surface of the prism row formed on the inner side of the prism sheet even if the direction of the emitted light from the entire exit surface is corrected in the normal direction of the entire exit surface by the prism sheet Is reflected from the inner surface by the other prism surface, but the other part is emitted from the prism sheet without receiving the inner surface reflection by the other prism surface. For this reason, in the luminance distribution of the light emitted from the outer surface of the prism sheet constituting the light emitting surface, side lobes are generated in a direction significantly inclined with respect to the normal direction, and light emission concentrated in the normal direction of the entire emission surface Therefore, it is difficult to improve the luminance in the required normal direction and the vicinity thereof.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a display having a high luminance in a required direction range in the luminance distribution of the light emitting surface, particularly in the normal direction of the entire emission surface and in the required range in the vicinity thereof, when used as a backlight of a display device. An object of the present invention is to provide a tandem type surface light source device capable of improving the quality of a display image by the device.

According to the present invention, as a solution to the above technical problem,
Refractive index having a primary light source and a light incident end surface for guiding the light emitted from the primary light source and receiving the light emitted from the primary light source, a light emitting surface for emitting the guided light, and a back surface on the opposite side a plurality of surface light emitting units having ng plate-shaped light guides, the light incident end faces are in the same direction, and a substantially continuous whole light emitting surface is formed by the light emitting surfaces of the plurality of surface light emitting units. Tandem surface light source devices arranged in parallel with each other,
A light leakage modulator is disposed on the back surface of the light guide, and the light leakage modulator includes a plurality of first refractive index region portions having a refractive index n1 (here, ng> n1) and a refractive index n2 (here, n2). > N1) a plurality of second refractive index region portions, and a third refractive index layer positioned on the composite layer and having a refractive index n3 (where n3> n1).
A plurality of prism rows extending in a direction parallel to both the light incident end surface and the light emitting surface of the light guide and arranged in parallel to each other are formed on the surface of the light leakage modulator or adjacent to the light leakage modulator. Has been
Each of the prism rows includes two prism surfaces, and the inclination of the prism surface of the prism surface closer to the primary light source is 80 to 105 ° with respect to the light exit surface, and A tandem surface light source device, wherein the inclination of the prism surface far from the primary light source is 35 to 55 ° with respect to the light exit surface;
Is provided.

  In one aspect of the present invention, the plurality of prism rows are formed on the surface of the third refractive index layer of the light leakage modulator. In one aspect of the present invention, a fourth refractive index layer having a refractive index n4 (here, ng> n4> n1) is interposed between the light guide and the light leakage modulator. In one aspect of the present invention, each of the plurality of first refractive index region portions is a gap. In one aspect of the present invention, each of the plurality of prism rows has a flat portion at a tip portion between the two prism surfaces. In one aspect of the present invention, a light reflecting element is disposed adjacent to the plurality of prism rows. In one aspect of the present invention, a polarization separation element is disposed on the light exit surface of the light guide. In one aspect of the present invention, a light diffusing element or a condensing element is disposed on the light exit surface of the light guide. In one aspect of the present invention, a plurality of prism rows extending along a direction substantially orthogonal to the light incident end surface of the light guide and arranged in parallel to each other are formed on the light exit surface of the light guide. Has been.

  According to the tandem surface light source device of the present invention as described above, the light leakage modulator and the plurality of prism rows are arranged in this order on the back surface of the light guide, and the primary of the two prism surfaces of the plurality of prism rows. The inclination of the prism surface close to the light source is 80 to 105 ° with respect to the light guide light exit surface, and the inclination of the prism surface far from the primary light source is 35 to 55 ° with respect to the light guide light exit surface. As a result, the luminance distribution on the light emitting surface has a high luminance in a required direction, particularly in the normal direction of the entire exit surface, and when used as a backlight of the display device, the display image quality of the display device can be improved. it can.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic view showing one embodiment of a tandem surface light source device according to the present invention, in which (A) shows a plan view thereof and (B) shows a sectional view thereof. FIG. 2 is a partially enlarged sectional view of the present embodiment.

  As shown in FIG. 1, the tandem surface light source device according to the present embodiment includes a plurality of surface light emitting units U1, U2, U3, U4.

  As shown in FIG. 2, the surface light emitting unit U <b> 2 includes a light guide 3, a light leakage modulator 8, and a primary light source 1. In the light guide 3, one side end surface is a light incident end surface 31, one surface substantially orthogonal thereto is a light emitting surface 33, and the surface opposite to the light emitting surface is a back surface 34. A linear primary light source 1 covered with the light source reflector 2 is disposed facing the light incident end face 31 of the light guide 3. The light guide 3 has a rectangular plate shape as a whole, and two main surfaces substantially orthogonal to the light incident end surface 31 are respectively a light emitting surface 33 and a back surface 34 substantially parallel to the XY plane. The light guide 3 has four side end faces, and one of the pair of side end faces parallel to the YZ plane is a light incident end face 31. The light incident end face 31 faces the primary light source 1 extending in the Y direction, and light emitted from the primary light source 1 enters the light incident end face 31 and is introduced into the light guide 3. The refractive index of the light guide 3 is ng.

  The light leakage modulator 8 is disposed on the back surface 34 of the light guide 3. The light leakage modulator 8 includes a plurality of first refractive index region portions 81 having a refractive index n1 (here, ng> n1) and a plurality of second refractive index region portions 82 having a refractive index n2 (here, n2> n1). And a third refractive index layer 83 positioned on the composite layer and having a refractive index n3 (here, n3> n1). A plurality of prism rows 9 arranged in parallel with each other are formed on the light leakage modulator 8. In the present embodiment, the prism row 9 is formed on the surface of the light leakage modulator 8, that is, the surface of the third refractive index layer 83, and is parallel to both the light incident end surface 31 and the light emitting surface 33 of the light guide. Extends in the direction. Each prism array 9 includes two prism surfaces 91 and 92. In the present invention, the third refractive index layer 83 is made of a layer having a flat surface, and a plurality of prism rows 9 are formed on the surface of the translucent member disposed on the surface of the third refractive index layer 83. May be. In this case, the plurality of prism rows 9 are formed adjacent to the light leakage modulator. The operation of the light leakage modulator 8 and the prism array 9 will be described later.

  The light reflecting element 5 is disposed adjacent to the plurality of prism rows 9, that is, the light reflecting element 5 is disposed to face the third refractive index layer 83 in which the prism rows 9 are formed. The light reflecting element 5 may be continuous with the light source reflector 2 and integrally formed therewith.

  As shown in FIG. 2, the light guide 3 has a wedge shape in which the light incident end face side is thick and the opposite side is thin. Further, a notch step portion 35 having a predetermined width and a predetermined depth is formed on the light emitting surface 33 side of the light guide 3 and on the light incident end surface 31 side. This notch step portion 35 has a function of receiving and holding the front end portion E of the adjacent surface light emitting unit U1 on the opposite side to the light incident end surface of the light guide and the light leakage modulator and prism array attached thereto. Have The light reflecting element 5 extends to the side end surface of the distal end portion of the light guide to which a light leakage modulator or the like is attached, and the light source reflector 2 extends to the bottom surface of the notch step portion 35 of the light guide. .

  The other surface light emitting units U1, U3, U4 are also equivalent to the surface light emitting unit U2, except that the light guide 3 of the surface light emitting unit U1 is not formed with a notch step. The surface light emitting units adjacent to each other are coupled by placing the tip end portion E of the other light guide in the notch step portion 35 of the light guide of one surface light emitting unit as described above. Thus, the entire surface emitting units U1 to U4 form the entire light exit surface 330 in which the light incident end surfaces 31 are in the same direction (leftward in FIG. 2) and substantially continuous in the X direction by the light exit surfaces 33. Has been. The entire emission surface 330 is on a plane substantially parallel to the XY plane.

  FIG. 3 is a schematic diagram showing the shape of the light guide 3. The dimension L1 in the X direction corresponding to the width of the light guide 3 is, for example, 10 mm to 100 mm, preferably 10 mm to 50 mm, and more preferably 10 mm to 30 mm. Moreover, the dimension L2 of the X direction corresponding to the width | variety of the notch step part 35 of the light guide 3 is 2 mm-15 mm, for example, Preferably it is 3 mm-10 mm, More preferably, it is 4 mm-8 mm. By making the dimension L1 100 mm or less, the light emitting area of the surface light emitting unit can be reduced, and the light emitted from the primary light source 1 and introduced into the light guide can be emitted from the light emitting surface with high luminous intensity, thus The brightness of the entire emission surface 330 can be sufficiently increased. On the other hand, by setting the dimension L1 to 10 mm or more, the light emitting area of the surface light emitting unit is prevented from becoming excessively small, and the light emitted from the primary light source 1 and introduced into the light guide is favorably emitted from the light emitting surface. Can do.

  The dimension T1 in the Z direction corresponding to the maximum thickness of the light guide 3 is, for example, 1 mm to 6 mm, preferably 2 mm to 4 mm, and more preferably 2.2 mm to 3.5 mm. The dimension T2 in the Z direction corresponding to the minimum thickness of the light guide is, for example, 0.4 mm to 1.5 mm, preferably 0.5 mm to 1.2 mm, and more preferably 0.7 mm to 1.0 mm. The dimension T3 in the Z direction corresponding to the height of the notch step 35 of the light guide 3 is, for example, 0.4 mm to 1.5 mm, preferably 0.5 mm to 1.2 mm, and more preferably 0.7 mm to 1.mm. 0 mm. By making the dimension T1 6 mm or less and the dimension T2 1.5 mm or less, the surface emitting unit can be thinned. On the other hand, by setting the dimension T1 to 1 mm or more and the dimension T2 to 0.4 mm or more, the light guide can be maintained at a required mechanical strength.

  In addition, although the dimension of the Y direction of the light guide 3 is not shown in figure, it can set suitably according to the length of the primary light source 1, for example, is 200 mm-400 mm. The wedge angle φ of the wedge-shaped light guide 3 is, for example, 2 ° to 10 °, preferably 3 ° to 6 °, and more preferably 3.5 ° to 5 °. By setting the wedge angle φ within the range of 2 ° to 10 °, light can be efficiently emitted from the light exit surface even if the light guide length is relatively short.

  As shown in FIG. 2, the light leakage modulator 8 includes a low refractive index region portion (first refractive index region portion) 81 having a refractive index n1 and a high refractive index having a refractive index n2 (where n2> n1). The composite layer 80 includes a refractive index region portion (second refractive index region portion) 82 and a light emission control functional layer (third refractive index layer) 83 having a refractive index n3 (here, n3> n1). The light emission control function layer 83 is in close contact with the composite layer 80, and the prism row 9 is formed on the surface opposite to the contact surface to the composite layer 80 (that is, the lower surface in FIG. 2). ing. As illustrated, in the composite layer 80, the low refractive index region portions 81 and the high refractive index region portions 82 are alternately arranged in the X direction orthogonal to the light incident end surface 31 of the light guide 3, Each of the low refractive index region 81 and the high refractive index region 82 extends uniformly in the Y direction parallel to the primary light source 1. That is, each of the low refractive index region portion 81 and the high refractive index region portion 82 has a strip shape extending in a direction parallel to the primary light source 1.

  The low refractive index region portion 81 and the high refractive index region portion 82 are not limited to those having a substantially rectangular cross section as shown in FIG. 2, that is, not limited to a rectangular parallelepiped alternate arrangement structure. For example, as shown in FIG. 7, the height H1 (or H2) of the low refractive index region 81 (or high refractive index region 82) is the same as that of the high refractive index region 82 (or low refractive index region 81). A structure having a structure larger than the height H2 (or H1), a structure having a substantially semicircular cross section, or a structure in which the cross-sectional shape of the high refractive index region portion 82 has an arc curve in part or in whole (arc curved surface) Or the like having a structure with) is applicable.

  FIG. 4 shows a schematic plan view of the positional relationship between the composite layer 80 and the primary light source 1. As the distance from the primary light source 1 increases, the width of the low refractive index region 81 (the dimension in the X direction orthogonal to the primary light source 1) gradually decreases, and the width of the high refractive index region 82 gradually increases.

  5 and 6 are schematic plan views showing modified examples of the composite layer 80. In these figures, the primary light source 1 is also shown. In the example of FIG. 5, the low refractive index region portions 81 and the high refractive index region portions 82 are alternately arranged with respect to both the X direction orthogonal to the primary light source 1 and the parallel Y direction. It has a lattice shape. As the distance from the primary light source 1 increases, the width of the low refractive index region 81 in the direction parallel to the primary light source 1 (dimension in the X direction perpendicular to the primary light source 1) gradually decreases. The width of the high refractive index region 82 is gradually increased. Further, the width of the low refractive index region 81 in the direction orthogonal to the primary light source 1 (the dimension in the Y direction parallel to the primary light source 1) is gradually increased from the center to both sides in the direction parallel to the primary light source 1. The width of the high refractive index region 82 in the direction perpendicular to the primary light source 1 is gradually increased. In the example of FIG. 6, the low refractive index region portion 81 and the high refractive index region portion 82 have a sea island structure in which the low refractive index region portion 81 forms an island portion and the high refractive index region portion 82 forms a sea portion. There is no. The size of the low refractive index region 81 gradually becomes smaller as the distance from the primary light source 1 increases. That is, as the distance from the primary light source 1 increases, the area ratio occupied by the low refractive index region 81 decreases.

  As the arrangement pattern of the low refractive index region portion 81 and the high refractive index region portion 82 in the composite layer 80, various forms such as a combination of the above patterns can be used.

  Next, the function of the light leakage modulator 8 in the surface light source device as described above, in particular, the emitted light luminance distribution control function will be described.

  The light emission control functional layer 83 has a function of supplying most of the light incident on the light leakage modulator 8 from the light guide 3 to the prism array 9. The maximum waveguide mode of light that is incident from the light incident end surface 31 of the light guide 3 and propagates inside the light guide is mainly defined by the refractive index difference between the low refractive index region 81 and the light guide 3. When the light beam travels from the light guide 3 to the low-refractive index region 81, the propagation mode light satisfying the total anti-reaction condition according to Snell's law, that is, the incident angle greater than the total reflection critical angle Θ1 determined by the relationship between ng and n1. All the light it has becomes a total reflection mode and can propagate inside the light guide. When the total reflection mode light encounters the high refractive index region 82 in the propagation process in the light guide, a new total reflection critical angle defined by the relationship between n2 and ng is satisfied when ng> n2> n1. Propagation mode light having an incident angle smaller than Θ2 (the relation Θ2> Θ1 is established) and larger than Θ1 leaks to the light emission control function layer 83 through the high refractive index region portion 82. Accordingly, by appropriately changing the occupation density of the high refractive index region portion 82 in the composite layer 80 (the area occupied by the high refractive index region portion 82 per unit area of the composite layer 80) in the plane of the composite layer 80 depending on the location, The amount of light that can reach the light emission control functional layer 83 can be controlled to a desired value. As means for changing the occupation density of the high refractive index region portion 82, a pattern as shown in FIG. 4 to FIG. 6 is used together, a method using other complicated pattern changes, a pattern shape similar to A method such as a method of changing the area of the high refractive index region 82 locally or a method of changing the arrangement pitch (P) using exactly the same pattern shape can be used.

  Next, Θ2 can be set to a desired value by appropriately selecting the relative refractive index difference between the refractive index ng of the light guide 3 and the refractive index n2 of the high refractive index region portion 82. Therefore, it is also possible to control the outgoing light distribution using this. For example, when the difference between ng and n2 is set to be smaller and the value of Θ2 is designed to be larger, the ratio of the light beam totally reflected at the interface between the high refractive index region portion 82 and the light guide 3 is reduced, and light leakage is caused. The efficiency is increased, and more light can be emitted from the light guide 3 to the high refractive index region 82 at a relatively close distance from the primary light source 1. Therefore, the distribution of the emitted light can be controlled also by locally changing the difference between ng and n2 in the light leakage modulator 8.

  As described above, according to the surface emitting unit including the light leakage modulator according to the present invention, the amount of light reaching the light emission control functional layer 83 can be freely adjusted by the above-mentioned several means. Even when the size and shape of the light guide 3 and the form of the primary light source 1 and the light emission efficiency in the light emission control function layer 83 change, the emission light distribution is basically controlled independently of these, It is easy to obtain a surface light source with excellent uniformity and good reproducibility. Such a feature is suitable for improving the luminance uniformity in the surface light emitting unit of the tandem surface light source device having a relatively short light guide length.

  The case of ng> n2 has been described above. Generally, the light controllability can be described by dividing (classifying) the following three cases according to the magnitude relationship of the refractive indexes n2, n3, and ng. In the surface light source device of the present invention, the relationships of n1 <ng, n1 <n2, and n1 <n3 are always established.

1) When n2 ≧ n3 ≧ ng or n3 ≧ n2 ≧ ng:
When this relationship is established, the propagation mode light inside the light guide having an incident angle larger than the critical angle Θ1 defined by the relationship between n1 and ng is all transmitted through the high refractive index region portion 82. The process proceeds to the emission control function layer 83. On the other hand, with respect to the light once incident on the light emission control function layer 83 and partially returning to the light guide 3, a higher order having an incident angle smaller than the critical angle Θ3 defined by the relationship between n3 and ng. Limited to mode light. Therefore, the probability that light is localized in the light emission control function layer 83 is the highest and tends to be strongly influenced by the light function control.

2) When n2 ≧ ng ≧ n3 or ng ≧ n2 ≧ n3:
When this relationship is established, only a part of the high-order propagation mode light having an incident angle larger than the critical angle Θ1 and smaller than the critical angle Θ3 passes to the light emission control function layer 83 via the high refractive index region portion 82. Transition. Since the other low-order mode light always satisfies the total reflection condition, the probability that more light propagates far from the primary light source 1 is higher than in the case of 1). On the other hand, with respect to the light once incident on the light emission control functional layer 83 and returning to the light guide 3, the mode is not restricted at all and all the mode light returns to the light guide 3. Can do. Therefore, the probability that light is localized in the light emission control function layer 83 is small, and an effect of suppressing the influence of the light function control appears slightly.

3) When n3 ≧ ng ≧ n2 or ng ≧ n3 ≧ n2:
When this relationship is established, only high-order propagation mode light having a total reflection angle larger than the total reflection critical angle Θ1 and smaller than the critical angle Θ2 defined by the relationship between n2 and ng is high refractive index region portion. It is possible to move to the light emission control functional layer 83 via 82. Since the other low-order propagation mode light always satisfies the total reflection condition, the probability that more light propagates far from the primary light source 1 is higher than in the case of 1). On the other hand, the light once incident on the light emission control function layer 83 partially returns to the light guide 3 is subjected to mode regulation by the critical angle Θ23 defined by the relationship between n3 and n2. Therefore, the probability that the light is localized in the light emission control function layer 83 is higher than the above 2), and tends to be slightly affected by the light function control.

  As described above, these different characteristics based on the magnitude relationship of the refractive index are preferably used according to the type and characteristics of the light control function of the light emission control function layer 83. In some cases, the above-described several refractive index magnitude relationships can be used together in the same surface light source device, and these relationships can be used locally in the plane of the light leakage modulator 8. In addition, as described in the above classification, the influence on the emitted light luminance distribution characteristic and the function expression effect varies depending on the relationship between the refractive indexes n2, n3, and ng. By changing the relationship between the refractive indexes, the emission light luminance distribution characteristic and the function manifestation effect can be controlled.

  FIG. 7 shows the relationship between the average thickness H1 of the low refractive index region portion 81 of the light leakage modulator 8 and the average width W2 of the high refractive index region portion 82. As shown in FIG. 7 is drawn in a state where the vertical direction is reversed from that in FIG. If the size of H1 and / or H2 is too large, unnecessary reflected light 27 is generated at the interface between the low refractive index region portion 81 and the high refractive index region portion 82, scattering or the like increases, and further the material The cost may increase, and H1 and H2 are suitably 200 microns or less, preferably 100 microns or less. However, when the surface light source device has a large area, these sizes are set larger than 200 microns as the screen size in the arrangement direction of the low refractive index region portion 81 and the high refractive index region portion 82 increases. The need to do so also arises.

  When the value of W2 / H1 is large, the incident light beam has a low probability of colliding with the side surface 25 of the low refractive index region 81, thereby suppressing unnecessary irregular reflection or transmitted light 27, thereby preventing the light leakage modulator. The leakage control of the propagation light from the light guide 3 to the light emission control function layer 83, which is the main purpose of the function, is achieved faithfully without any obstacles. This does not depend on the presence or absence of the additional layer 11 described later.

  Further, light having a smaller angle (low-order mode light) formed by incident light to the high refractive index region portion 82 with respect to the arrangement direction of the low refractive index region portion 81 and the high refractive index region portion 82 of the light leakage modulator 8 is emitted. When it is necessary to actively leak light to the control function layer 83, the value of W2 / H1 needs to be set larger. Therefore, as described above, the relationship between the refractive indexes of n2 and ng that restricts the mode of light passing through the high refractive index region portion 82 is also greatly related to the design of the value of W2 / H1. For example, when the value of n2 / ng is smaller than 1, the light leakage mode (26) of the low-order mode light to the high refractive index region portion 82 is greatly limited, so the value of W2 / H1 is a relatively small value, It may be about 1 to 2. However, if it is necessary to design n2 / ng to be 1 or a value larger than 1, if the light leakage to the light emission control function layer 83 of the low-order mode light is more necessary, the incident angle is considerably large. Since it is necessary to leak light up to low-order mode light and pass through the high refractive index region 82, the value of W2 / H1 must be set to 2 or more. For the purpose of suppressing the ratio of the irregular reflected light 27 as much as possible and performing the light leakage control faithfully, the value of W2 / H1 needs to be 3 or more, preferably 5 or more, more preferably 8 or more. is there. When it is necessary to actively leak propagation mode light having an incident angle close to 90 degrees, it is preferable to use a mode conversion function from a low-order mode to a high-order mode (for example, using a wedge-shaped light guide). . However, if W2 / H1 is larger than necessary, there is a relationship with the emission area of the light guide 3, the size of H1, and the necessary resolution as a surface light source, but the pattern size of the light leakage part is larger than the resolution of the human eye. Therefore, it is not preferable because it may be visually recognized as a bright spot as a defect. W2 / H1 is preferably limited to 30 or less, and more preferably in the range of 10 or less.

  In general, the low-refractive index region 81 and the high-refractive index region 82 may have a substantially rectangular cross-sectional shape (it is not necessary to have a special cross-sectional shape), and W2 / H1 is preferably large. This is because, as described above, unnecessary irregular reflection hardly occurs at the interface 25 between the low refractive index region portion 81 and the high refractive index region portion 82, and the light leakage modulator 8 is made of a photocurable resin. This is because there are several manufacturing advantages such as easy mold fabrication when the mold is transferred and molded, and improved mold release from the mold during molding.

  However, the substantially rectangular cross-sectional shape described here means that the low-refractive index region portion 81 and the high-refractive index region portion 82 and the high-refractive index region portion 82 are not necessarily rectangular in shape, for example, the low-refractive index region portion 81 and the high-refractive index region. The side part surface which mutually contact | connects the area | region part 82 also includes what forms some taper shape. These are rather preferable as means for improving the releasability when removing the molded product from the mold (drawing taper) when the light leakage modulator 8 is manufactured by mold transfer.

  Next, the function of the plurality of prism rows 9 in the surface light source device as described above, particularly the directional light reflection control function will be described.

  The main functions of the plurality of prism rows 9 are as described above. The light introduced from the light guide 3 into the light leakage modulator 8 and incident on the light emission control function layer 83 is totally reflected to guide the light in a desired direction. This is directed to the normal direction (Z direction) of the light emitting surface 33 of the body 3 and the vicinity thereof. For this reason, the inclination of the prism surface 91 on the side close to the primary light source 1 of the two prism surfaces of the prism row 9 is set to 80 to 105 ° with respect to the light emitting surface 33, and is on the side far from the primary light source 1. The inclination of the prism surface 92 is set to 35 to 55 ° with respect to the light emitting surface 33.

  The light incident on the light emission control function layer 83 travels to the surface of the light emission control function layer 83 where the plurality of prism rows 9 are formed. These prism rows 9 extend in parallel to each other and in the Y direction that is substantially perpendicular to the X direction, which is the main propagation direction of light in the light guide within the XY plane. This is because light rises most efficiently in the normal direction of the light guide light exit surface when the ridge line of the prism array 9 is always orthogonal to the main propagation direction in the XY plane of incident light. In the present embodiment, the prism row 9 extends in the Y direction substantially parallel to the light incident end face 31 of the light guide 3.

  By appropriately designing the prism surfaces 91 and 92 of the prism array 9, the peak emission angle can be set freely. One side of the prism array 9 [surface far from the primary light source 1] (second prism surface) 92 is inclined at an angle of 35 ° to 55 ° with respect to the light emitting surface 33 of the light guide 3. By setting the other side surface [surface near the primary light source 1] (first prism surface) 91 to an inclination angle of 80 to 105 degrees with respect to the light emitting surface 33 of the light guide 3. The light reflected from the inner surface of the prism array 9 re-enters the light guide 3 and directs the peak light of the emitted light when exiting from the light emitting surface 33 in the direction of the normal line of the light emitting surface 33, and The angular distribution can be narrowed (for example, full width at half maximum of 15 to 25 degrees). In order to increase the directivity in the normal direction of the light exit surface, the inclination angle of the second prism surface 92 is preferably in the range of 35 to 50 degrees, particularly preferably in the range of 40 to 45 degrees, and that of the first prism surface 91 is preferably Is in the range of 80 to 100 degrees, particularly preferably 85 to 95 degrees.

  The pitch of the prism rows 9 to be formed can be selected as appropriate within a processable range, but is preferably in the range of 10 to 500 μm, and more preferably in the range of 30 to 300 μm. For the purpose of preventing moire, the pitch of the prism row 9 may be changed partially or continuously. When the surface light source device becomes larger or the ratio of the length to the thickness of the light guide 3 becomes larger and the uniformity on the light exit surface tends to be lowered, the pitch of the prism rows 9 is changed partially or continuously. Therefore, the effect of improving the uniformity can be enhanced. Further, the prism surface may be a flat surface or a curved surface with a predetermined curvature, and when it is a curved surface, the angular distribution of the emitted light can be made somewhat smaller or larger.

  The function of the second prism surface 92 of the prism array 9 is to totally reflect the light and direct it in the normal direction of the light exit surface 33 of the light guide 3.

  In the prism row 9 as described above, the light utilization efficiency of the prism-shaped tip is low. Therefore, even if the tip of the prism row 9 is flattened or processed into any shape such as a polygonal cross-section or a curved cross-section, the optical performance is not significantly affected. As shown in FIG. 8, it is preferable to flatten the tip end portion of the prism row 9 to form the flat portion 93 because damage to the prism surface due to friction is reduced.

  FIG. 9 is a schematic partial cross-sectional view showing a surface light emitting unit of still another embodiment of the tandem surface light source device according to the present invention. In this figure, members similar to those in FIGS. 1 to 8 are denoted by the same reference numerals. In the present embodiment, an additional layer (fourth refractive index layer) 11 having a refractive index n4 (here, n4> n1) is interposed between the light leakage modulator composite layer 80 and the light guide 3. The additional layer 11 performs a function similar to that of the high refractive index region portion 82. Even when n2 = n3, the additional layer 11 can play a similar role in place of the high refractive index region portion 82.

  As described above, the feature of the present embodiment is that the additional layer 11 is formed on the back surface 34 of the light guide 3 by uniform coating, and the like, and this additional layer 11 is similar to the high refractive index region portion 82 of the composite layer 80. In addition, n2 = n3, that is, the same material can be used for the high refractive index region portion 82 and the light emission control function layer 83 inside the light leakage modulator. This is advantageous for cost reduction in industrial production.

  As a means for obtaining incident light to the light leakage modulator 8 with better directivity, the refractive index n2 (or n4) of the high refractive index region 82 (or the additional layer 11) and the light guide refractive index ng are set to n2 <ng (Or n4 <ng) is set. As a result, the light beam incident on the high refractive index region 82 can be limited to a light beam in a propagation mode within a predetermined limited range as described above.

  However, in the parallel plate type waveguide, since the low-order mode light is accumulated in the light guide 3 as the distance from the primary light source 1 is increased, the low-order mode light is always converted into a high-order mode. Is preferably provided. As this means, as shown in FIG. 9, the thickness of the light guide 3 is gradually reduced as the distance from the primary light source 1, that is, a wedge shape, and / or mixing of a light diffusing material, It is conceivable to provide a rough surface form, a microprism, a lattice shape, a notch or the like to the light emitting surface of the light guide 3. In particular, the introduction of the wedge shape is an effective means capable of controlling the mode conversion continuously and easily with respect to the distance from the primary light source 1.

  Further, in the present invention, the light is emitted from the light guide 3 and is narrowed by the light leakage modulator 8 and the prism array 9 to be brightened and introduced into the light guide 3. In order to appropriately control the field of view according to the purpose without causing a decrease in luminance as much as possible, the light emitted from the light 33 is placed on the light guide light emitting surface 33 as shown in FIG. The light diffusing elements 6 can be arranged adjacent to each other. In addition, by arranging the light diffusing element 6 in this way, it is possible to suppress glare, brightness spots, and the like that cause deterioration in quality and to improve quality. The light diffusing element 6 has an incident surface 61 on which light from the light guide light exit surface is incident and an exit surface 62 on the opposite side.

  The light diffusing element 6 may be formed integrally with the light guide 3, or the light diffusing element 6 may be individually placed on the light guide light emitting surface 33. It is preferable to arrange the light diffusing elements 6 individually. When the light diffusing element 6 is individually mounted, the surface of the light diffusing element 6 adjacent to the light guide light emitting surface 33 is prevented from sticking with the light guide light emitting surface 33. It is preferable to provide an uneven structure. Similarly, it is necessary to consider sticking between the light diffusing element 6 and the liquid crystal display element disposed thereon, and an uneven structure is also provided on the light diffusing element 6. Is preferred. In the case of providing this concavo-convex structure only for the purpose of preventing sticking, it is preferable that the average inclination angle θa is 0.7 ° or more, more preferably 1 ° or more, and more preferably It is 1.5 degrees or more.

Here, the average inclination angle θaθa is measured in accordance with ISO 4287 / 1-1984 using a stylus type surface roughness meter, and the obtained inclination function f (x) is obtained with x in the measurement direction. To the following equations (1) and (2)
ΔaΔa = (1 / L) ∫ 0 L | (d / dx) f (x) | dx (1)
θaθa = tan −1 (ΔaΔa) (2)
Can be obtained using Here, L is the measurement length, and ΔaΔa is a tangent of the average inclination angle θaθa.

In the present invention, it is preferable to use the light diffusing element 6 having a light diffusing characteristic for appropriately diffusing light emitted from the light guide 3 in consideration of a balance of luminance characteristics, visibility, and quality. That is, when the light diffusibility of the light diffusing element 6 is low, it is difficult to sufficiently widen the viewing angle and the visibility is lowered, and the effect of improving the quality tends to be insufficient. If it is too high, the effect of narrowing the field of view by the light leakage modulator 8 and the prism array 9 is impaired, and the total light transmittance is also lowered and the brightness tends to be lowered. Therefore, in the light diffusing element 6 of the present invention, an element having a full width at half maximum of 1 to 13 degrees in the emitted light luminous intensity distribution (in the XZ plane) when parallel light is incident is used. The full width at half maximum of the light diffusing element 6 is preferably in the range of 3 to 11 degrees, more preferably in the range of 4 to 8.5 degrees. In the present invention, the full width at half maximum of the emitted light intensity distribution (in the XZ plane) of the light diffusing element 6 is, as shown in FIG. 11, how much the parallel rays incident on the light diffusing element 6 are diffused and spread when emitted. This means the full width angle (Δθ H ) of the divergence angle at half the peak value in the luminous intensity distribution (in the XZ plane) of the light transmitted through and diffused through the light diffusing element 6 (in the XZ plane).

  Such light diffusion characteristics can be imparted by mixing a light diffusing agent in the light diffusing element 6 or imparting a concavo-convex structure to at least one surface of the light diffusing element 6. The degree of the concavo-convex structure formed on the surface differs depending on whether it is formed on one surface of the light diffusing element 6 or on both surfaces. In the case of forming a concavo-convex structure on one surface of the light diffusing element 6, the average inclination angle is preferably in the range of 0.8 to 12 degrees, more preferably 3.5 to 7 degrees, and more Preferably it is 4 to 6.5 degrees. When the concavo-convex structure is formed on both surfaces of the light diffusing element 6, the average inclination angle of the concavo-convex structure formed on one surface is preferably in the range of 0.8 to 6 degrees, more preferably 2 to 2. It is 4 degrees, more preferably 2.5 to 4 degrees. In this case, in order to suppress a decrease in the total light transmittance of the light diffusing element 6, it is preferable to make the average inclination angle on the incident surface side of the light diffusing element 6 larger than the average inclination angle on the exit surface side. Further, the haze value of the light diffusing element 6 is preferably in the range of 8 to 82% from the viewpoint of improving luminance characteristics and improving visibility, more preferably in the range of 30 to 70%, more preferably 40. It is in the range of ~ 65%.

  The surface light source device of the present invention is suitable for a display device having a relatively large size such as a monitor of a desktop personal computer or a liquid crystal television. When used in such a display device, a relatively wide viewing angle is required and high luminance is required. Therefore, as the light diffusing element 6, it is necessary to have a light diffusibility to obtain a wide viewing angle, and it is preferable to use a light emitting element having a full width at half maximum of 6 to 13 degrees in the emitted light luminous intensity distribution (in the XZ plane), More preferably, it is 6.5 to 11 degrees, and more preferably 7 to 9 degrees. Moreover, as a haze value, it is preferable that it is the range of 50 to 82%, More preferably, it is 60 to 75%, More preferably, it is the range of 65 to 70%. Furthermore, when forming an uneven | corrugated structure in the surface of the light-diffusion element 6, it is preferable that the average inclination | tilt angle is the range of 4.5-12 degree | times, More preferably, it is 5.5-8.5 degree | times, More Preferably it is the range of 6-7 degrees.

  In the surface light source device of the present invention, when the light diffusing element 6 as described above is used, the light condensing property that the full width at half maximum of the emitted light luminance distribution (in the XZ plane) from the light guide 3 is about 19 to 26 degrees. Since the use of the relatively weak light guide 3, the light leakage modulator 8, and the prism array 9 and the use of the light diffusing element 6 having relatively weak light diffusibility can suppress a decrease in luminance due to diffusion on the YZ plane, It may be preferable from the viewpoint of improving luminance. In this case, the light diffusing element 6 needs to have a light diffusibility to obtain a wide viewing angle, and it is preferable to use a light diffuser having a full width at half maximum of 1 to 8 degrees in the emitted light luminous intensity distribution (in the XZ plane). More preferably, it is in the range of 2 to 8 degrees, more preferably 3 to 7 degrees. The haze value is preferably in the range of 8 to 70%, more preferably 30 to 65%, and still more preferably 40 to 60%. Furthermore, when forming an uneven | corrugated structure in one surface of the light-diffusion element 6, it is preferable that the average inclination | tilt angle is the range of 0.8-7 degree, More preferably, it is 3-6.5 degree, and more Preferably it is the range of 3.5-6 degrees. When the uneven structure is formed on both sides, the average inclination angle of one surface thereof is preferably in the range of 0.8 to 4 degrees, more preferably 1 to 4 degrees, more preferably 2 to 4 degrees. It is a range.

  In the present invention, using the light diffusing element 6 having anisotropy in light diffusibility (an anisotropic light diffusing element such as an anisotropic light diffusing sheet) increases the total light transmittance of the light diffusing element 6, The light emitted from the deflecting element 4 can be efficiently diffused and the luminance can be improved, which is preferable. For example, in a light source device including a surface light emitting unit in which a linear cold cathode tube is arranged as a primary light source 1 on one end face of a light guide 3, a narrow field of view is narrowed mainly in the XZ plane by a light leakage modulator 8 and a prism array 9. As shown in the figure, the light narrowed in the XZ plane can be further diffused by the light diffusing element 6 to widen the viewing angle. However, when an isotropic diffusive element is used as the light diffusing element 6, light is equally diffused even in the YZ plane that is not narrowed by the light deflecting element, resulting in a decrease in luminance. It will be. Therefore, as shown in FIG. 12, by using the light diffusing element 6 having anisotropic diffusivity that has higher light diffusibility in the XZ plane than in the YZ plane, the light leakage modulator 8 and the prism array 9 are used. This makes it possible to increase the diffusion of light in the XZ plane with a narrower field of view and weaken the diffusion of light in the YZ plane that has not been narrowed in the field of view. It is possible to diffuse efficiently, and the reduction in luminance can be minimized.

  Regarding the anisotropic diffusivity of such a light diffusing element 6, what kind of anisotropy the light diffusing element 6 is used depends on the anisotropy only in the XZ plane and the YZ plane as described above. However, it can be appropriately selected according to the shape of the light leakage modulator 8, the shape and arrangement of the prism array 9, the use of the surface light source device, and the like. That is, as shown in FIG. 13, an arbitrary surface (including the exit surface normal of the light diffusing element 6 and an arbitrary direction within the exit surface (Pn direction (n = 1, 2,...)) ( Assuming a ZP-n plane (n = 1, 2,...)), Anisotropy is imparted by differentiating the full width at half maximum of the emitted light intensity distribution (in the XZ plane) on these arbitrary planes. Can do. The largest full width at half maximum of the ZP-n plane is the maximum full width at half maximum, and the smallest full width at half maximum is the minimum full width at half maximum. Similarly, with respect to the average inclination angle of the concavo-convex structure imparting anisotropic diffusibility to the light diffusing element 6, the average inclination angle in any Pn direction where the ZP-n plane and the light diffusing element 6 (XY plane) intersect It is possible to impart anisotropy of the average inclination angle by making the difference. At this time, the largest average inclination angle in the P-n direction is the maximum average inclination angle, and the smallest is the minimum average inclination angle.

  For example, when a linear cold-cathode tube is disposed so as to face the side end face parallel to the YZ plane of the light guide 3, and the primary light source 1 is used, the light leakage modulator 8 and the prism array 9 are mainly narrowed in the XZ plane. Therefore, the light diffusing element 6 having an anisotropic diffusivity that effectively diffuses the light emitted from the light guide light emitting surface 33 in the XZ plane and does not diffuse in the YZ plane is provided. It is best to use. Therefore, the light diffusing element 6 preferably has an anisotropic diffusibility that exhibits the maximum full width at half maximum on the XZ plane and the full width at half maximum on the YZ plane. Similarly, the concavo-convex structure formed in the light diffusing element 6 is preferably configured or arranged so as to have a maximum average inclination angle in the Y direction and a minimum average inclination angle in the X direction.

  The light diffusing element 6 having such anisotropic diffusibility also has a light diffusing characteristic for appropriately diffusing the light emitted from the light guide light emitting surface 33 in consideration of the balance of luminance characteristics, visibility, quality, and the like. It is necessary to use the light diffusing element 6 having. That is, when the light diffusibility of the light diffusing element 6 is low, it is difficult to sufficiently widen the viewing angle and the visibility is lowered, and the effect of improving the quality tends to be insufficient. If it is too high, the effect of narrowing the field of view by the light leakage modulator 8 and the prism array 9 is impaired, and the total light transmittance is also lowered and the brightness tends to be lowered. Therefore, a light having a maximum full width at half maximum of the emitted light luminous intensity distribution (in the XZ plane) in the range of 1 to 13 degrees is used, preferably in the range of 3 to 11 degrees, and more preferably in the range of 4 to 9 degrees. The ratio of the maximum full width at half maximum to the full width at half maximum (maximum full width at half maximum / full width at half maximum) is preferably in the range of 1.1 to 20, more preferably in the range of 2 to 15, more preferably 4 to 10. It is a range. This is because when the maximum full width at half maximum / minimum full width at half maximum is 1.1 or more, the light use efficiency can be improved and the luminance can be increased, and when it is 20 or less, the luminance is reduced due to strong light diffusibility. This is because it can be suppressed.

  In the case of forming a concavo-convex structure on one surface of the light diffusing element 6, the maximum average inclination angle is preferably in the range of 0.8 to 15 degrees, more preferably 3.5 to 11 degrees, More preferably, it is 4 to 9 degrees. Further, from the same viewpoint as the maximum full width at half maximum / minimum full width at half maximum, the ratio of the maximum average inclination angle to the minimum average inclination angle (maximum average inclination angle / minimum average inclination angle) is in the range of 1.1 to 20. More preferably, it is the range of 2-15, More preferably, it is the range of 4-10. The uneven structure may be formed on both surfaces of the light diffusing element 6. In this case, in order to suppress a decrease in the total light transmittance of the light diffusing element 6, the average of the incident surface side of the light diffusing element 6 It is preferable to make the inclination angle larger than the average inclination angle on the exit surface side. Further, the haze value of the light diffusing element 6 is preferably in the range of 8 to 82% from the viewpoint of improving luminance characteristics and improving visibility, more preferably in the range of 30 to 70%, more preferably 40. It is in the range of ~ 65%.

  Examples of the diffusibility imparting structure of the light diffusing element 6 having such anisotropic diffusibility include concavo-convex structures as shown in FIGS. 14 to 16. The concavo-convex structure shown in FIG. 14 is an array structure in which a large number of lens rows 6a such as lenticular lens rows extending long on one axis are arranged substantially in parallel. As such an arrangement pitch of the lens rows, a pitch that hardly causes moire is selected with respect to the pitch of the liquid crystal display elements used as the display elements and the arrangement pitch of the lens rows such as the prism rows of the light deflection element 4, or randomly. It is preferable to use a uniform arrangement pitch. Usually, the arrangement pitch of the lens rows is preferably in the range of 1 to 70 μm, more preferably 5 to 40 μm, and more preferably in the range of 10 to 30 μm from the viewpoint of ease of manufacture and prevention of moire. The average inclination angle in the direction orthogonal to the longitudinal direction of the lens array is preferably in the range of 0.8 to 15 degrees from the viewpoint of improving luminance and improving visibility, and more preferably 3.5 to 11 degrees. Preferably it is the range of 4-9 degree | times.

  The concavo-convex structure shown in FIG. 15 is a structure in which a large number of cylindrical lens-shaped bodies 6b are discretely arranged. The arrangement interval of the cylindrical lens-shaped bodies may be a regular pitch or a random arrangement pitch. In general, the arrangement pitch of the cylindrical lens-shaped bodies is preferably in the range of 1 to 70 μm, more preferably 5 to 40 μm, more preferably in the range of 10 to 30 μm from the viewpoint of ease of manufacture and prevention of moire. is there. The average inclination angle in the direction orthogonal to the longitudinal direction of the cylindrical lens-shaped body is preferably 0.8 to 15 degrees from the viewpoint of improving luminance and improving visibility, and more preferably 3.5 to 11 degrees. Preferably it is the range of 4-9 degree | times. Such a discrete array structure has a line intersecting the surface where the light diffusing element 6 is required to exhibit the full width at half maximum and the exit surface of the light diffusing element 6 and the longitudinal direction of the cylindrical lens-shaped body. It is preferable to arrange so as to increase the probability of being substantially orthogonal. In addition, there is a high probability that a line intersecting the surface where the light diffusing element 6 is required to exhibit the minimum full width at half maximum and the exit surface of the light diffusing element 6 is substantially parallel to the longitudinal direction of the cylindrical lens-shaped body. It is preferable to arrange them as follows.

  The uneven structure shown in FIG. 16 is a hairline structure. The average inclination angle in the direction orthogonal to the direction in which the hairline 6c extends is preferably 0.8 to 15 degrees from the viewpoint of improving luminance and improving visibility, more preferably 3.5 to 11 degrees, and more preferably 4 to 5 degrees. The range is 9 degrees. The direction in which the hairline extends is preferably a direction substantially orthogonal to a line intersecting the surface where the light diffusing element 6 is required to exhibit the full width at half maximum and the exit surface of the light diffusing element 6.

  By imparting a mat structure to at least one of the surface on which the uneven structure imparting such anisotropic diffusibility and the back surface thereof are provided, glare, brightness spots, etc. can be suppressed and the quality can be improved. it can. However, if the light diffusibility of the mat structure is increased, the anisotropic diffusibility may be impaired and the luminance may be lowered. Therefore, it is preferable to provide a mat structure having a relatively weak light diffusibility. Such a mat structure preferably has an average inclination angle in the range of 0.5 to 5 degrees, more preferably 0.8 to 4 degrees, and more preferably 1 to 3.5 degrees. The average inclination angle of the mat structure when the mat structure is provided on the surface of the anisotropy imparting concavo-convex structure refers to the average inclination angle of the mat structure itself excluding the average inclination angle caused by the concavo-convex structure. Such an average inclination angle can be measured in a portion having no concavo-convex structure or in a direction parallel to the longitudinal direction of the concavo-convex structure, measured by a stylus roughness meter, and image analysis of the cross-sectional shape of the light diffusing element 6. It can be measured using a method, an atomic force microscope or the like.

  In the present invention, the light emitted from the light guide light emitting surface 33 is emitted in a specific direction such as the normal direction using the light leakage modulator 8 and the prism array 9, and the emitted light is light having anisotropic diffusibility. The light can be emitted in a desired direction using the diffusing element 6. In this case, the light diffusing element 6 can be provided with both the functions of anisotropic diffusion and light deflection angle. For example, in the case where a lenticular lens array or a cylindrical lens shaped body is used as the concavo-convex structure, both functions of anisotropic diffusion and light deflection can be provided by making the cross-sectional shape asymmetric.

  Moreover, in this invention, the light-diffusion element 6 can also be made to contain the light-diffusion material in order to adjust the viewing angle as a surface light source device and to improve a quality. As such a light diffusing material, transparent fine particles having a refractive index different from that of the material constituting the light diffusing element 6 can be used, and examples thereof include silicone beads, polystyrene, polymethyl methacrylate, fluorinated methacrylate. And those consisting of a homopolymer such as a polymer or a copolymer. As the light diffusing material, it is necessary to appropriately select the content, particle size, refractive index and the like so as not to impair the appropriate diffusion effect by the light diffusing element 6. For example, the refractive index of the light diffusing material is such that if the difference in refractive index from the material constituting the light diffusing element 6 is too small, the diffusion effect is small. It is preferable to set it as the range of 01-0.1, More preferably, it is 0.03-0.08, More preferably, it is the range of 0.03-0.05. In addition, if the particle size of the diffusing material is too large, the scattering is strong and causes glare and brightness reduction, and if it is too small, coloring occurs. Therefore, the average particle size is preferably in the range of 0.5 to 20 μm. More preferably, it is 2-15 micrometers, More preferably, it is the range of 2-10 micrometers.

  In the present invention, a light condensing element such as a light condensing film can be used instead of the light diffusing element 6 as described above. In contrast to the light diffusing element 6, this condensing element has a function of narrowing (that is, condensing) the angular distribution of light emitted from the light guide light emitting surface 33. Examples of the condensing element include those having a concavo-convex surface structure having a relatively large tilt angle component for increasing the condensing efficiency. As this condensing element, an element having anisotropy in condensing property can be used as in the case of the light diffusing element 6. Hereinafter, the embodiment is shown.

  FIG. 17 is a schematic plan view of the condensing element 18, and FIGS. 18 and 19 are partial cross-sectional views thereof. The condensing element 18 has a large number of minute convex portions 18b formed on one surface of a light-transmitting sheet-like substrate 18a.

  As shown in FIG. 17, the shape (planar shape) seen in the Z direction of the minute projections 18b, that is, the projection shape on the surface of the sheet-like substrate 18a is an ellipse. That is, the minute protrusion 18b has shape anisotropy in the XY plane, and its X-direction dimension x is, for example, 20 to 100 μm, and its Y-direction dimension y is, for example, 15 to 50 μm. Moreover, the Z direction dimension z of the micro convex part 18b shown by FIG. 19 is 8-25 micrometers, for example. In the present embodiment, the center of the planar shape of the minute convex portion 18b corresponds to the top portion O of the minute convex portion 18b, and among the plurality of cross sections including the normal line NL of the sheet-like substrate 18a passing through the top portion O. The shape of the minute convex portion 8b in one XZ cross section (FIG. 18) is substantially semi-elliptical. Further, the shape of the minute protrusion 18b in the YZ cross section (FIG. 19), which is another one of the plurality of cross sections including the normal line NL of the sheet-like substrate 18a passing through the top O, is substantially semicircular.

  Therefore, the maximum value and the minimum value of the average inclination angles respectively appearing in a plurality of cross sections that pass through the center of the planar shape of the minute protrusion 18b and include the normal direction of the sheet-like base material 18a are respectively in the YZ cross section and XZ Appears in the cross section. The maximum value and / or the minimum value of these average inclination angles are, for example, 25 to 55 degrees, preferably 30 to 50 degrees, and more preferably 35 to 45 degrees. The difference between the maximum value and the minimum value of the average inclination angle is appropriately set depending on the required degree of light collecting anisotropy. For example, it is 5 degrees or more, preferably 10 degrees or more, and more preferably 15 degrees or more. The

  The average inclination angle θa of the surface of the minute projection 18b can be obtained as described above.

  In addition, an inclination angle formed by a straight line passing through the top portion O and the skirt portion of the minute convex portion 18b with the surface of the sheet-like base material 18a is φx in the XZ section (the skirt portion is Sx: see FIG. 18), and the YZ section. Is φy (the bottom is Sy: see FIG. 19). In this embodiment, φx is the minimum value of the tilt angle, and φy is the maximum value of the tilt angle. The maximum value φx and / or the minimum value φy is, for example, in the range of 35 to 60 degrees, and preferably in the range of 40 to 50 degrees. As described above, by setting the maximum value φx and / or the minimum value φy of the inclination angle within the range of 35 to 60 degrees, a better light condensing action can be obtained in which the traveling direction of light approaches the normal direction. The difference between the maximum value and the minimum value of the tilt angle is appropriately set depending on the required degree of condensing anisotropy. For example, it is 5 degrees or more, preferably 10 degrees or more, more preferably 15 degrees or more. .

  A large number of minute convex portions 18b have a short direction (a direction corresponding to a cross section in which the maximum average inclination angle appears) and a long direction (a direction corresponding to a cross section in which the minimum average inclination angle appears) in the planar shape, respectively. They are arranged discretely on one surface of the sheet-like substrate 18a so as to be parallel to each other. The condensing element 18 is arranged so that the cross section where the minimum value of the average inclination angle appears is substantially orthogonal to the extending direction of the linear primary light source 1.

The ratio of the area occupied by the minute projections 18b on the surface of the sheet-like base material 18a is appropriately set according to the required degree of light condensing, but is, for example, 40 to 80%, preferably 50 to 70%. is there. The number density of the minute projections 18b on the surface of the base material sheet 18, for example 100 to 3000 pieces / mm 2, preferably 300 to 2,000 pieces / mm 2, more preferably is 500 to 1000 / mm 2 . Furthermore, the projection area on the surface of the sheet-like base material 18a (surface orthogonal to the direction of the normal line NL) is, for example, 200 to 4000 μm 2 .

It is preferable that the shape of the surface of the minute convex portion 18 b has a specific relationship with the angular distribution of the incident light to the light condensing element 18. That is, the angle distribution when the diffused outgoing light from the light guide 3 enters the condensing element 18 in at least one of the cross section in which the minimum value of the average inclination angle of the minute convex portion 18b appears and the cross section in which the maximum value appears. The traveling direction of the light component having a half-value half-width angle equal to or less than the half-value half-width angle is subjected to a condensing action so as to approach the direction of the normal NL (Z direction). FIG. 20 is a schematic diagram for explaining such a light collecting action. Here, a state in which light incident at a half-value half-width angle θ h1 in the angular distribution of light incident on the lower surface (incident surface) of the sheet-like substrate 18a of the light condensing element 18 is refracted and emitted from the surface of the minute convex portion 18b. Has been. The angle θ 3 formed by the refracted output light with respect to the Z direction is smaller than the angle θ 2 formed by the light within the condensing element 18 with respect to the Z direction, where α is the inclination angle of the surface of the minute convex portion 18b at the refractive output position. This is a condition for efficient light collection. This condition is α> sin −1 [sin (θ h1 ) / n], where n is the refractive index of the light collecting element 18. By making the ratio of the region satisfying such a condition 20% or more of the whole on the surface of the minute convex portion 18b, a good condensing effect can be obtained.

  As described above, the light diffusing element 6 having the light diffusing anisotropy or the light condensing element 18 having the light collecting anisotropy is used in combination with the light leakage modulator 8 and the prism array 9 in an appropriate arrangement. The light distribution controlled by the light leakage modulator 8 and the prism array 9 can be selectively modified appropriately within a required cross section so that a desired viewing angle characteristic can be finally obtained.

  In the present invention, instead of using the condensing element 18 having the above-described condensing anisotropy, a light incident end face is formed on the light exit surface 33 of the light guide 3 in order to exhibit the same anisotropic condensing function. A plurality of prism rows may be formed that extend along a direction substantially orthogonal to the line 31 and are arranged in parallel to each other. As this prism row, for example, those having apex angles of about 100 degrees arranged with a pitch of 10 to 100 μm are exemplified.

  The primary light source 1 is a linear light source extending in the Y direction. As the primary light source 1, for example, a fluorescent lamp or a cold cathode tube can be used. In the present invention, the primary light source 1 is not limited to a linear light source, and a point light source such as an LED light source, a halogen lamp, or a metahalo lamp may be used, or a plurality of these point light sources may be used. What was arrange | positioned with the appropriate space | interval can also be used. The light source reflector 2 guides the light from the primary light source 1 to the light guide 3 with little loss. As the material, for example, a plastic film having a metal-deposited reflective layer on the surface can be used.

  A reflection member similar to the light source reflector 2 can be attached to the side end face other than the light incident end face 31 of the light guide 3. As the light reflecting element 5, for example, a plastic sheet having a metal vapor deposition reflecting layer on the surface can be used. In the present invention, the light reflecting element 5 may be a light reflecting layer or the like formed by metal vapor deposition or the like on the back surface 34 or the like of the light guide 3 instead of the reflecting sheet. In the case where the internal reflection by the second prism surface 92 of the light emitted from the primary light source 1 and guided by the light guide 32 and reaching the prism row 9 via the light leakage modulator 8 is total reflection, the light reflecting element 5 may be omitted. However, even in this case, the light that enters the light guide light exit surface 33 from the outside, passes through the light leakage modulator 8, and exits from the second prism surface 92 is reflected by the light reflecting element 5 to be reflected in the prism array 9. In addition, it is preferable that the light is incident again on the light leakage modulator 8 and used for light emission from the viewpoint of improving the light utilization efficiency.

  The light guide 3, the light diffusing element 6 and the light condensing element 18 of the present invention can be made of a synthetic resin having a high light transmittance. Examples of such synthetic resins include methacrylic resins, acrylic resins, polycarbonate resins, polyester resins, and vinyl chloride resins. In particular, methacrylic resins are optimal because of their high light transmittance, heat resistance, mechanical properties, and molding processability. Such a methacrylic resin is a resin mainly composed of methyl methacrylate, and preferably has a methyl methacrylate content of 80% by weight or more. When forming the surface structure such as the rough surface of the light guide 3, the light diffusing element 6 and the light condensing element 18, the hairline, the prism array, the lenticular lens array or the minute convex part, the transparent synthetic resin plate is formed with the desired surface structure. It may be formed by hot pressing using a mold member, or may be formed simultaneously with molding by screen printing, extrusion molding, injection molding or the like. The structural surface can also be formed using heat or a photocurable resin. Furthermore, on the surface of a transparent base material such as a polyester film, an acrylic resin, a polycarbonate resin, a vinyl chloride resin, a polymethacrylimide resin or the like, a rough substrate made of an active energy ray curable resin is used. A surface structure or a lens array arrangement structure may be formed on the surface, or such a sheet may be bonded and integrated on a separate transparent substrate by a method such as adhesion or fusion. As the active energy ray-curable resin, polyfunctional (meth) acrylic compounds, vinyl compounds, (meth) acrylic acid esters, allyl compounds, (meth) acrylic acid metal salts, and the like can be used.

  The light guide 3 is also included, and the low refractive index region 81, the high refractive index region 82, the light emission control functional layer 83, and the additional layer 11 need to be adjusted relative to each other as described above. There is. In particular, the additional layer 11 needs to use a material having a refractive index lower than that of the light guide in order to adjust the propagation mode inside the light guide. In general, most of the materials constituting the layer having a relatively low refractive index have a glass transition temperature (Tg) of room temperature or lower, and considering heat resistance and refractive index control, a copolymer having a relatively large Tg should be employed. Is preferred.

  Useful relatively low refractive index materials include methyl methacrylate, fluorinated alkyl (meth) acrylate, fluorinated alkyl-α-fluoroacrylate, α-fluoroacrylate, pentafluorophenylmethyl methacrylate, pentafluorophenyl-α-fluoro. It is preferably constituted by a homopolymer selected from a monomer group of acrylate and pentafluorophenyl methacrylate and / or a highly transparent copolymer capable of adjusting the refractive index selected from the monomer group. In addition, in the low refractive index layer (additional layer) interposed between the light guide and the light leakage modulator, there is a method in which magnesium fluoride which is an inorganic material having a low refractive index is vapor deposited. On the other hand, examples of the material having a relatively high refractive index compared to the material having the relatively low refractive index include polycarbonate resin, polyester resin, acrylic resin, polyolefin resin, and the like. By selecting a material having a higher refractive index as the light guide, the range of material selection for the low refractive index material layer can be expanded.

  As a constituent material of the high refractive index region portion 82, the light emission control function layer 83, and the additional layer 11 related to the light leakage modulator, an ultraviolet curable resin composition can be used. Examples of the ultraviolet curable resin composition include an ultraviolet curable composition mainly composed of a polymerizable compound having an acryloyl group or a methacryloyl group in the molecule, an ultraviolet sensitive radical polymerization initiator and / or an ultraviolet absorber.

  Examples of the polymerizable compound having a (meth) acryloyl group in the molecule include photopolymerizable oligomers, polyfunctional (meth) acrylates, and monofunctional (meth) acrylates.

  As the photopolymerizable oligomer, a urethane poly (meth) acrylate oligomer obtained by reacting a polyisocyanate having two or more isocyanate groups in the molecule with a compound having a hydroxyl group and a (meth) acryloyl group in the molecule, And an epoxy poly (meth) acrylate oligomer obtained by reacting an epoxy compound having two or more epoxy groups with a compound having a carboxyl group and a (meth) acryloyl group in the molecule.

  Specifically, diisocyanate compounds such as isophorone diisocyanate, tetramethylxylylene diisocyanate, xylylene diisocyanate, tolylene diisocyanate, and hydroxyethyl (meth) acrylate, hydroxypropyl (meth) aclute, tetramethylol methane tri (meth) acrylate, glycerin Urethane poly (meth) acrylate oligomer, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, tetrabromo obtained by reacting with a hydroxyl group-containing (meth) acrylate compound such as di (meth) acrylate Epoxy poly (meth) acrylate obtained by reaction of epoxy compounds such as bisphenol A diglycidyl ether and (meth) acrylic acid Mention may be made of the door oligomers or the like as a representative.

  Polyfunctional (meth) acrylate compounds include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, and tripropylene glycol di (meth). Acrylate, polypropylene glycol di (meth) aclute, polybutylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) Acrylate, 2,2-bis [4- (meth) acryloyloxyphenyl] -propane, 2,2-bis [4- (meth) acryloyloxyethoxyphenyl] -propane, 2,2-bis [4- (meth) ) Acryloyloxydiethoxyphenyl] -propane, 2,2-bis [4- (meth) acryloyloxypentaethoxyphenyl] -propane, 2,2-bis [4- (meth) acryloyloxyethoxy-3-phenylphenyl] -Propane, bis [4- (meth) acryloylthiophenyl] sulfide, bis [4- (meth) acryloyloxyphenyl] -sulfone, bis [4- (meth) acryloyloxyethoxyphenyl] -sulfone, bis [4- ( (Meth) acryloyloxydiethoxyphenyl] -sulfone, bis [4- (meth) acryloyloxypentaethoxyphenyl] -sulfone, bis [4- (meth) acryloyloxyethoxy-3-phenylphenyl] -sulfone, bis [4 -(Meth) acryloyloxy Toxi-3,5-dimethylphenyl] -sulfone, bis [4- (meth) acryloyloxyphenyl] -sulfide, bis [4- (meth) acryloyloxyethoxyphenyl] -sulfide, bis [4- (meth) acryloyloxy Pentaethoxyphenyl] -sulfide, bis [4- (meth) acryloyloxyethoxy-3-phenylphenyl] -sulfide, bis [4- (meth) acryloyloxyethoxy-3,5-dimethylphenyl] -sulfide, 2,2 -Bis [4- (meth) acryloyloxyethoxy-3,5-dibromophenylpropane], trimethylolpropane tri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, dipentaeri A sitolol hexa (meth) acrylate etc. can be mentioned.

  Monofunctional (meth) acrylate compounds include phenyl (meth) acrylate, benzyl (meth) acrylate, phenylethyl (meth) acrylate, phenoxyethyl (meth) acrylate, paracumylphenol ethylene oxide modified (meth) acrylate, isobornyl ( (Meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) ) Acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylhexyl ( ) Acrylate, n-hexyl (meth) acrylate, 2-humanoxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, Examples thereof include tetrahydrofurfuryl (meth) acrylate and phosphoethyl (meth) acrylate.

  In the present invention, the above compounds may be used alone or in combination of two or more.

  A plurality of surface emitting units including the primary light source 1, the light source reflector 2, the light guide 3, the light leakage modulator 8, the prism array 9, and the light reflecting element 5, and the light diffusing element 6 or the light collecting element 18. A liquid crystal display device using the tandem surface light source device of the present invention as a backlight is configured by disposing a liquid crystal display element on the light emitting surface of the tandem type surface light source device (emission surface 62 of the light diffusing element 6). Is done. The liquid crystal display device is observed by an observer through a liquid crystal display element.

  By the way, in a typical liquid crystal display element, only a specific polarization component is used, and for this reason, a polarizing plate is disposed on the side where illumination light from the backlight is incident. That is, of the light incident on the liquid crystal display element from the surface light source device, only a specific polarization component that passes through the polarizing plate is effectively used for display. The polarization component in the direction orthogonal to the specific polarization component is absorbed by the polarizing plate and is not effectively used for display. Thus, from the viewpoint of improving the light use efficiency as the liquid crystal display device, it is preferable to emit only the polarization component that transmits the polarizing plate of the liquid crystal display element from the surface light source device.

  Therefore, in the present invention, as shown in FIG. 21, the polarization separation element 12 is arranged on the light diffusion element 6 (or the polarization separation element 12 is arranged under the light diffusion element 6), and those The polarization component in the same direction as the transmission polarization direction of the incident-side polarizing plate of the liquid crystal display element LC disposed above is transmitted, and the polarization component in the direction orthogonal thereto is reflected and led to the light guide 3 again. Is preferred. According to this, the polarization component reflected by the polarization separation element 12 is transmitted through the light diffusing element 6, the light guide 3, the light leakage modulator 8, the prism array 9, and the reflection element 5, or at the boundary between them. Alternatively, the polarization direction is changed during reflection, and thus when the light is directed again from the light guide light exit surface 33 to the polarization separation element 12, a part of the light is converted into a polarization component that is transmitted through the polarization separation element 12. ing. By repeating such an action, the required amount of polarized component light traveling from the polarization separation element 12 to the liquid crystal surface element LC is increased as compared with the case where no polarization separation element is disposed. Thus, the brightness of the liquid crystal display device is improved and the image display performance is improved.

  The polarization separation element 12 transmits one (transmission polarization plane) polarization component of the light from the light guide 3 and emits the light upward in FIG. 21, while the other (reflection polarization plane) polarization component is the light diffusion element 6. The transmission polarization plane and the transmission direction of the incident side polarizing plate of the liquid crystal display element LC are set so as to coincide with each other.

  As such a polarization separation element 12, a plurality of sheets having birefringence and sheets not so are alternately laminated with a predetermined thickness, and the directionality of each sheet at the time of the lamination is set to an adjacent sheet. It is preferable to use a material in which the difference in refractive index between the light beams is small in the transmission polarization plane and large in the reflection polarization plane. Further, the polarization separating element 12 is preferably a combination of a film in which a cholesteric liquid crystal layer is laminated and a quarter wavelength plate. In this case, the circularly polarized light in a certain direction is transmitted and the circularly polarized light in the reverse direction is reflected by the cholesteric liquid crystal layer. At this time, linearly polarized light can be extracted by arranging a quarter-wave plate on the cholesteric liquid crystal layer. The direction of the linearly polarized light is set as a transmission polarization plane, and the direction is set so as to coincide with the transmission direction of the incident side polarizing plate of the liquid crystal display element LC.

  In order to improve the polarization separation ability of the polarization separation element 12, it is necessary to concentrate the luminance distribution of the light incident on the polarization separation element 12 in the normal direction. It is preferable that the direction of incident light is 25 ° or less with respect to the normal direction of the polarization separation element 12 because the transmittance of the polarization separation element 12 with respect to the transmission polarization plane and the reflectance with respect to the reflection polarization plane are increased. The direction of the incident light with respect to the normal direction of the polarization beam splitter 12 is more preferably 20 ° or less, and further preferably 15 ° or less.

  For this reason, the full width at half maximum in the luminance distribution of the light incident on the polarization separation element 12 includes the XZ plane (light guide body) including the direction perpendicular to the light incident end face 31 of the light guide body 3 and the normal direction of the light emitting surface 33. It is necessary that the angle be 50 ° or less in a direction parallel to the main direction in which light travels, preferably 45 ° or less, and more preferably 40 ° or less. On the other hand, if the full width at half maximum is made too small, the viewing angle as a liquid crystal display device becomes too narrow. Therefore, the full width at half maximum on the XZ plane in the luminance distribution of light incident on the polarization separation element 12 is preferably 20 ° or more. , More preferably 25 ° or more, particularly preferably 30 ° or more. In the present invention, in order to make the full width at half maximum in the luminance distribution of the light incident on the polarization separation element 12 as described above, the full width at half maximum of the luminance distribution in the XZ plane of the light emitted from the light diffusing element 6 is What should I do. In the present invention, the full width at half maximum of the luminance distribution means an angle of the full width of the spread angle at the half value with respect to the peak value in the luminance distribution.

  In general, as shown in FIG. 2, in a surface light source device using a large number of prism rows 9 extending in the Y direction substantially parallel to the light guide light incident end face 31, the light emitted from the light guide light exit surface 33. The luminance distribution varies depending on the direction. Normally, the luminance distribution of the light emitted from the light guide 3 is narrow on the XZ plane, but the YZ surface (light guide) including the direction parallel to the prism row 9 and the normal direction of the light output surface 33 is used. 3 in a plane parallel to the light incident end face 31, that is, a direction perpendicular to the X direction which is the main direction in the XY plane in which light travels in the light guide 3). Distribution is wide. For this reason, the full width at half maximum of the luminance distribution of the incident light on the polarization separation element 12 in the YZ plane is preferably 80 ° or less, more preferably 70 ° or less, and particularly preferably 60 ° or less. On the other hand, if the full width at half maximum is too small, the viewing angle as a liquid crystal display device becomes too narrow. Therefore, the full width at half maximum is preferably 40 ° or more, more preferably 45 ° or more, and particularly preferably 50 ° or more. It is. In the present invention, in order to make the full width at half maximum in the luminance distribution of the light incident on the polarization separating element 12 as described above, the full width at half maximum of the luminance distribution in the YZ plane of the light emitted from the light diffusing element 6 is What should I do.

  When this polarization separation element 12 is used, in particular, as shown in FIG. 8, a flat portion 93 is formed at the tip between the two prism surfaces 91 and 92 so as to be reflected by the polarization separation element 12. It is preferable that part of the light guided into the light guide 3 is emitted from the flat portion 93, reflected by the light reflecting element 5, and efficiently re-entered into the light leakage modulator 8 and the light guide 3. . Thereby, the utilization efficiency of the light emitted from the primary light source 1 is further enhanced.

  In the present invention, the polarization separating element 12 may be disposed between the plurality of surface emitting units U1 to U4 and the light diffusing element 6. In this case, it becomes easier to concentrate the luminance distribution of the light incident on the polarization beam splitter 12 in the normal direction.

  FIG. 22 is a schematic partial sectional view showing another embodiment of the tandem surface light source device according to the present invention. In this figure, the same reference numerals are given to the same parts as in FIGS.

  In the present embodiment, all of the surface light emitting units U1, U2, U3, etc. are those in which notch step portions are not formed in the light guide 3 like the surface light emitting unit U1 of the above embodiment. The surface light emitting units adjacent to each other are coupled by placing the tip portion E of the other light guide on the end near the light incident end surface 31 of the light guide 3 of the one surface light emitting unit as described above. Has been. Also in this embodiment, the light incident end faces 31 are in the same direction (leftward in FIG. 2) in the entire surface emitting units. However, in the present embodiment, the light emitting surfaces 33 of the respective surface light emitting units are arranged in parallel with each other but slightly differently. In the present invention, the overall light exit surface 330 formed by the whole of the light exit surfaces 33 arranged in a different shape that is not exactly on the same plane is also a substantially continuous overall exit surface in the X direction. And In the present embodiment, the distribution of light emitted from the entire emission surface 330, particularly the direction of the distribution peak, is slightly different from that of the above-described embodiment due to the above-described uneven form. This light distribution, particularly the direction of the distribution peak, can be set to a desired direction by appropriately setting the shape of the prism row formed on the surface of the light leakage modulator 8 or adjacent to the light leakage modulator.

  This embodiment has the same function as the above embodiment. Furthermore, according to this embodiment, since the shape of all the surface light-emitting units is the same, it is possible to reduce the types of components constituting the surface light source device.

  Hereinafter, the present invention will be described by way of examples.

[Example 1]
The surface light source device (the number of surface emitting units is 4) described with reference to FIG. As the light guide 3 constituting each surface emitting unit, a refractive index ng of 1.49 and the following dimensions shown in FIG. 3 were used:
T1 = 3.5mm
T2 = 0.7mm
L1 = 30mm
In addition, the Y direction dimension which is not illustrated was 350 mm.

  As the light leakage modulator 8, the refractive index n1 of the low refractive index region (air) 81 is 1.0, the refractive index n2 of the high refractive index region 82 is 1.50, and the refractive index n3 of the light emission control functional layer 83. Used was 1.50. The pitch of the prism rows 9 formed on the surface of the light emission control functional layer 83 is 50 μm, the inclination of the prism surface 91 on the side close to the primary light source 1 is 85 ° with respect to the light emission surface 33, and the side far from the primary light source 1 The prism surface 92 having an inclination of 45 ° with respect to the light emitting surface 33 was used.

  The primary light source 1 of each surface light emitting unit was turned on, and the luminous intensity distribution on the entire emission surface 330 was measured. The measurement results are shown in FIG. According to this, the angle of the distribution peak is about −5 degrees (the sign is a negative inclination toward the primary light source side with respect to the light emitting surface normal), the full width at half maximum is 19 degrees, and directivity is improved. It can be seen that excellent and very high normal luminance can be obtained.

[Example 2]
The inclination of the prism surface 91 near the primary light source 1 of the prism array 9 formed on the surface of the light emission control function layer 83 of the light leakage modulator 8 is set to 90 ° with respect to the light output surface 33, and the tip of the prism array 9 A surface light source device was manufactured in the same manner as in Example 1 except that the portion was cut out and flattened as shown in FIG. 8 and the height of the prism row was 20 μm.

  The primary light source 1 of each surface light emitting unit was turned on, and the luminous intensity distribution on the entire emission surface 330 was measured. The measurement results are shown in FIG. According to this, the angle of the distribution peak is about −5 degrees (the sign is a negative inclination toward the primary light source with respect to the light emitting surface normal), the full width at half maximum is 20 degrees, and directivity is improved. It can be seen that excellent and very high normal luminance can be obtained.

[Comparative example]
The inclination of the prism surface 91 near the primary light source 1 of the prism row 9 formed on the surface of the light emission control function layer 83 of the light leakage modulator 8 is set to 65 ° with respect to the light emission surface 33, and is located on the side far from the primary light source 1. A surface light source device was manufactured in the same manner as in Example 1 except that the prism surface 92 having an inclination of 34 ° with respect to the light emitting surface 33 was used.

  The primary light source 1 of each surface light emitting unit was turned on, and the luminous intensity distribution on the entire emission surface 330 was measured. The measurement results are shown in FIG. According to this, the angle of the distribution peak is about 15 degrees (the sign is a negative inclination toward the primary light source side with respect to the light emitting surface normal), the full width at half maximum is 32 degrees, and the distribution is widely directed. It can be seen that only a lower normal luminance is obtained because of its low nature.

It is a schematic diagram which shows embodiment of the tandem type surface light source device by this invention. It is a partial expanded sectional view of the embodiment of FIG. It is a schematic diagram which shows the shape of a light guide. It is a typical top view which shows the positional relationship of the low refractive index area | region part and high refractive index area | region part of a composite layer, and a primary light source. It is a typical top view which shows the positional relationship of the low refractive index area | region part and high refractive index area | region part of a composite layer, and a primary light source. It is a typical top view which shows the positional relationship of the low refractive index area | region part and high refractive index area | region part of a composite layer, and a primary light source. It is a figure which shows the average thickness of the low refractive index area | region part of a light leakage modulator, and the average width of a high refractive index area | region part. It is a typical fragmentary sectional view which shows the modification of a light emission control functional layer and a prism row. It is a typical fragmentary sectional view which shows the surface emitting unit of embodiment of the tandem type | mold surface light source device by this invention. It is a schematic diagram which shows embodiment of the tandem type surface light source device by this invention. It is explanatory drawing of the half value full width of an emitted light luminous intensity distribution (XZ plane). It is a figure which shows the emitted light luminous intensity distribution (XZ plane and YZ plane) of an anisotropic light diffusing element. It is explanatory drawing of the anisotropic diffusivity of a light-diffusion element. It is a schematic diagram which shows the uneven structure of an anisotropic light-diffusion element. It is a schematic diagram which shows the uneven structure of an anisotropic light-diffusion element. It is a schematic diagram which shows the uneven structure of an anisotropic light-diffusion element. It is a schematic plan view of a condensing element. It is a fragmentary sectional view of the condensing element of FIG. It is a fragmentary sectional view of the condensing element of FIG. It is a schematic diagram for demonstrating the condensing effect | action of a condensing element. It is a schematic diagram which shows embodiment of the tandem type surface light source device by this invention. It is a schematic diagram which shows embodiment of the tandem type surface light source device by this invention. It is a figure which shows the emitted light luminous intensity distribution (XZ plane) of a tandem type surface light source device. It is a figure which shows the emitted light luminous intensity distribution (XZ plane) of a tandem type surface light source device. It is a figure which shows the emitted light luminous intensity distribution (XZ plane) of a tandem type surface light source device.

Explanation of symbols

U1, U2, U3, U4 Surface light emitting unit 1 Primary light source 2 Light source reflector 3 Light guide 31 Light incident end surface 33 Light exit surface 330 Overall exit surface 34 Back surface 35 Notch step portion E Light guide end portion 5 Light reflecting element 6 Light Diffusing element 61 Entrance surface 62 Exit surface 6a Lens array 6b Cylindrical lens shaped body 6c Hairline 8 Light leakage modulator 80 Composite layer 81 Low refractive index region (first refractive index region)
82 High refractive index region (second refractive index region)
83 Light emission control functional layer (third refractive index layer)
DESCRIPTION OF SYMBOLS 9 Prism row | line | column 91 1st prism surface 92 2nd prism surface 93 Flat part 11 Additional layer (4th refractive index layer)
DESCRIPTION OF SYMBOLS 12 Polarization separation element LC Liquid crystal display element 18 Condensing element 18a Sheet-like base material 18b Minute convex part O Top part NL Normal of sheet-like base material Sx, Sy Bottom

Claims (9)

  1. Refractive index having a primary light source and a light incident end surface for guiding the light emitted from the primary light source and receiving the light emitted from the primary light source, a light emitting surface for emitting the guided light, and a back surface on the opposite side a plurality of surface light emitting units having ng plate-shaped light guides, the light incident end faces are in the same direction, and a substantially continuous whole light emitting surface is formed by the light emitting surfaces of the plurality of surface light emitting units. Tandem surface light source devices arranged in parallel with each other,
    A light leakage modulator is disposed on the back surface of the light guide, and the light leakage modulator includes a plurality of first refractive index region portions having a refractive index n1 (here, ng> n1) and a refractive index n2 (here, n2). > N1) a plurality of second refractive index region portions, and a third refractive index layer positioned on the composite layer and having a refractive index n3 (where n3> n1).
    A plurality of prism rows extending in a direction parallel to both the light incident end surface and the light emitting surface of the light guide and arranged in parallel to each other are formed on the surface of the light leakage modulator or adjacent to the light leakage modulator. Has been
    Each of the prism rows includes two prism surfaces, and the inclination of the prism surface of the prism surface closer to the primary light source is 80 to 105 ° with respect to the light exit surface, and A tandem type surface light source device, wherein the inclination of the prism surface far from the primary light source is 35 to 55 ° with respect to the light exit surface.
  2. 2. The tandem surface light source device according to claim 1, wherein the plurality of prism rows are formed on a surface of a third refractive index layer of the light leakage modulator.
  3. The fourth refractive index layer having a refractive index n4 (here, ng> n4> n1) is interposed between the light guide and the light leakage modulator. The tandem type surface light source device described in 1.
  4. 4. The tandem surface light source device according to claim 1, wherein each of the plurality of first refractive index region portions includes a gap.
  5. 5. The tandem surface light source device according to claim 1, wherein each of the plurality of prism rows has a flat portion at a tip portion between the two prism surfaces.
  6. The tandem surface light source device according to claim 1, wherein a light reflecting element is disposed adjacent to the plurality of prism rows.
  7. The tandem surface light source device according to claim 1, wherein a polarization separation element is disposed on a light exit surface of the light guide.
  8. The tandem surface light source device according to claim 1, wherein a light diffusing element or a condensing element is disposed on a light emitting surface of the light guide.
  9. The light exit surface of the light guide is formed with a plurality of prism rows extending in a direction substantially perpendicular to the light incident end surface of the light guide and arranged in parallel to each other. The tandem surface light source device according to claim 1.
JP2004296351A 2004-10-08 2004-10-08 Tandem type surface light source device Pending JP2006108033A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2004296351A JP2006108033A (en) 2004-10-08 2004-10-08 Tandem type surface light source device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2004296351A JP2006108033A (en) 2004-10-08 2004-10-08 Tandem type surface light source device

Publications (1)

Publication Number Publication Date
JP2006108033A true JP2006108033A (en) 2006-04-20

Family

ID=36377478

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2004296351A Pending JP2006108033A (en) 2004-10-08 2004-10-08 Tandem type surface light source device

Country Status (1)

Country Link
JP (1) JP2006108033A (en)

Cited By (30)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009016965A1 (en) * 2007-07-27 2009-02-05 Sharp Kabushiki Kaisha Illuminating device, and liquid crystal display device
JP2009277553A (en) * 2008-05-15 2009-11-26 Hitachi Maxell Ltd Backlight, optical member, lenticular lens sheet, and liquid crystal display device
WO2009147877A1 (en) * 2008-06-04 2009-12-10 シャープ株式会社 Light guiding body, illuminating device and liquid crystal display device
JP2010010053A (en) * 2008-06-30 2010-01-14 Fuji Xerox Co Ltd Light guide, beam radiating device, static eliminator, image formation structure object, image forming device, and method of manufacturing light guide
WO2010004798A1 (en) * 2008-07-08 2010-01-14 シャープ株式会社 Lighting device and liquid crystal display device
JPWO2008038754A1 (en) * 2006-09-29 2010-01-28 東レ株式会社 Surface light source and liquid crystal display device using the same
WO2010016315A1 (en) * 2008-08-07 2010-02-11 シャープ株式会社 Illuminating device and liquid crystal display device
WO2009145548A3 (en) * 2008-05-27 2010-03-04 Lg Electronics Inc. Led back-light unit and liquid crystal display device using the same
WO2010038516A1 (en) 2008-09-30 2010-04-08 シャープ株式会社 Illuminating device, planar light source device and liquid crystal display device
WO2010038520A1 (en) * 2008-09-30 2010-04-08 シャープ株式会社 Illuminating device, display device and television receiver
WO2010041499A1 (en) * 2008-10-09 2010-04-15 シャープ株式会社 Illuminating device, display device and television receiver
WO2010050274A1 (en) * 2008-10-27 2010-05-06 シャープ株式会社 Illuminating apparatus, display apparatus and television receiver
JP2010192433A (en) * 2009-01-22 2010-09-02 Hitachi Consumer Electronics Co Ltd Backlight unit, and liquid crystal display using same backlight unit
WO2010098173A1 (en) * 2009-02-25 2010-09-02 シャープ株式会社 Lighting device
WO2010109731A1 (en) * 2009-03-25 2010-09-30 シャープ株式会社 Illumination device, display device, and television receiving device
KR20110067534A (en) * 2009-12-14 2011-06-22 엘지전자 주식회사 Optical assembly, backlight unit having the same, and display apparatus thereof
JP2011142085A (en) * 2010-01-07 2011-07-21 Lg Innotek Co Ltd Optical assembly and display device
JP2011151005A (en) * 2010-01-20 2011-08-04 Samsung Electronics Co Ltd Backlight assembly with multiple light guide plates
CN102165247A (en) * 2008-09-30 2011-08-24 夏普株式会社 Illuminating device, display device and television receiver
CN102177393A (en) * 2008-10-31 2011-09-07 夏普株式会社 Illuminating device, display device and television receiver
EP2284594A3 (en) * 2009-08-13 2011-10-26 Edward Pakhchyan Display including waveguide, micro-prisms and micro-mechanical light modulators
CN102227587A (en) * 2008-11-27 2011-10-26 国立大学法人东北大学 Planar light source device
JP2011530718A (en) * 2008-08-08 2011-12-22 スリーエム イノベイティブ プロパティズ カンパニー Light guide with viscoelastic layer for managing light
US8220981B2 (en) 2008-05-27 2012-07-17 Lg Electronics Inc. Liquid crystal display having a plurality of modules
US8243231B2 (en) 2009-08-27 2012-08-14 Lg Electronics Inc. Backlight unit and display apparatus including the same
US8317387B2 (en) 2009-06-15 2012-11-27 Lg Electronics Inc. Light emitting diode package, and backlight unit and display device using the same
JP5157903B2 (en) * 2006-06-20 2013-03-06 日本電気株式会社 Lighting device, lighting method, and display device
US8674929B2 (en) 2009-12-14 2014-03-18 Lg Electronics Inc. Optical assembly, backlight unit including the same, and display apparatus including the backlight unit
US8872992B2 (en) 2009-06-23 2014-10-28 Lg Innotek Co., Ltd. Optical assembly, backlight unit including the same, and display apparatus including the backlight unit
EP2372418B1 (en) * 2010-03-30 2019-06-26 LG Innotek Co., Ltd. Backlight unit and display apparatus

Cited By (43)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5157903B2 (en) * 2006-06-20 2013-03-06 日本電気株式会社 Lighting device, lighting method, and display device
JPWO2008038754A1 (en) * 2006-09-29 2010-01-28 東レ株式会社 Surface light source and liquid crystal display device using the same
US8339539B2 (en) 2007-07-27 2012-12-25 Sharp Kabushiki Kaisha Illumination device and liquid crystal display device
WO2009016965A1 (en) * 2007-07-27 2009-02-05 Sharp Kabushiki Kaisha Illuminating device, and liquid crystal display device
CN102588887A (en) * 2007-07-27 2012-07-18 夏普株式会社 Illumination device and liquid crystal display device
JP2009277553A (en) * 2008-05-15 2009-11-26 Hitachi Maxell Ltd Backlight, optical member, lenticular lens sheet, and liquid crystal display device
US8220981B2 (en) 2008-05-27 2012-07-17 Lg Electronics Inc. Liquid crystal display having a plurality of modules
WO2009145548A3 (en) * 2008-05-27 2010-03-04 Lg Electronics Inc. Led back-light unit and liquid crystal display device using the same
CN102047174A (en) * 2008-05-27 2011-05-04 Lg电子株式会社 LED back-light unit and liquid crystal display device using the same
US8189135B2 (en) 2008-05-27 2012-05-29 Lg Electronics Inc. LED back-light unit and liquid crystal display device using the same
CN102047174B (en) * 2008-05-27 2016-01-27 Lg电子株式会社 LED backlight unit and use the liquid crystal indicator of this LED backlight unit
US8113704B2 (en) 2008-05-27 2012-02-14 Lg Electronics Inc. Backlight unit having light guide plates
CN102016399B (en) 2008-06-04 2012-11-07 夏普株式会社 Light guiding body, illuminating device and liquid crystal display device
US8684588B2 (en) 2008-06-04 2014-04-01 Sharp Kabushiki Kaisha Light guide elements for display device
WO2009147877A1 (en) * 2008-06-04 2009-12-10 シャープ株式会社 Light guiding body, illuminating device and liquid crystal display device
JP2010010053A (en) * 2008-06-30 2010-01-14 Fuji Xerox Co Ltd Light guide, beam radiating device, static eliminator, image formation structure object, image forming device, and method of manufacturing light guide
WO2010004798A1 (en) * 2008-07-08 2010-01-14 シャープ株式会社 Lighting device and liquid crystal display device
WO2010016315A1 (en) * 2008-08-07 2010-02-11 シャープ株式会社 Illuminating device and liquid crystal display device
US9285531B2 (en) 2008-08-08 2016-03-15 3M Innovative Properties Company Lightguide having a viscoelastic layer for managing light
JP2011530718A (en) * 2008-08-08 2011-12-22 スリーエム イノベイティブ プロパティズ カンパニー Light guide with viscoelastic layer for managing light
CN102165247A (en) * 2008-09-30 2011-08-24 夏普株式会社 Illuminating device, display device and television receiver
WO2010038520A1 (en) * 2008-09-30 2010-04-08 シャープ株式会社 Illuminating device, display device and television receiver
WO2010038516A1 (en) 2008-09-30 2010-04-08 シャープ株式会社 Illuminating device, planar light source device and liquid crystal display device
RU2484365C2 (en) * 2008-09-30 2013-06-10 Шарп Кабусики Кайся Illumination device, surface light source and led display
JP5198570B2 (en) * 2008-09-30 2013-05-15 シャープ株式会社 Lighting device, surface light source device, and liquid crystal display device
WO2010041499A1 (en) * 2008-10-09 2010-04-15 シャープ株式会社 Illuminating device, display device and television receiver
WO2010050274A1 (en) * 2008-10-27 2010-05-06 シャープ株式会社 Illuminating apparatus, display apparatus and television receiver
CN102177393A (en) * 2008-10-31 2011-09-07 夏普株式会社 Illuminating device, display device and television receiver
CN102227587A (en) * 2008-11-27 2011-10-26 国立大学法人东北大学 Planar light source device
JP2010192433A (en) * 2009-01-22 2010-09-02 Hitachi Consumer Electronics Co Ltd Backlight unit, and liquid crystal display using same backlight unit
WO2010098173A1 (en) * 2009-02-25 2010-09-02 シャープ株式会社 Lighting device
WO2010109731A1 (en) * 2009-03-25 2010-09-30 シャープ株式会社 Illumination device, display device, and television receiving device
US8317387B2 (en) 2009-06-15 2012-11-27 Lg Electronics Inc. Light emitting diode package, and backlight unit and display device using the same
US9262971B2 (en) 2009-06-23 2016-02-16 Lg Innotek Co., Ltd. Optical assembly, backlight unit including the same, and display apparatus including the backlight unit
US8872992B2 (en) 2009-06-23 2014-10-28 Lg Innotek Co., Ltd. Optical assembly, backlight unit including the same, and display apparatus including the backlight unit
EP2284594A3 (en) * 2009-08-13 2011-10-26 Edward Pakhchyan Display including waveguide, micro-prisms and micro-mechanical light modulators
US8243231B2 (en) 2009-08-27 2012-08-14 Lg Electronics Inc. Backlight unit and display apparatus including the same
US8674929B2 (en) 2009-12-14 2014-03-18 Lg Electronics Inc. Optical assembly, backlight unit including the same, and display apparatus including the backlight unit
KR20110067534A (en) * 2009-12-14 2011-06-22 엘지전자 주식회사 Optical assembly, backlight unit having the same, and display apparatus thereof
KR101676872B1 (en) * 2009-12-14 2016-11-16 엘지전자 주식회사 optical assembly, backlight unit having the same, and display apparatus thereof
JP2011142085A (en) * 2010-01-07 2011-07-21 Lg Innotek Co Ltd Optical assembly and display device
JP2011151005A (en) * 2010-01-20 2011-08-04 Samsung Electronics Co Ltd Backlight assembly with multiple light guide plates
EP2372418B1 (en) * 2010-03-30 2019-06-26 LG Innotek Co., Ltd. Backlight unit and display apparatus

Similar Documents

Publication Publication Date Title
US7153017B2 (en) Light deflection element and light source apparatus using the same
US7780330B2 (en) Elongated illuminators configuration for LCD displays
TWI364600B (en) An illumination device an image display device using the illumination device and a light diffusing board used by the devices
KR100867066B1 (en) Surface light source device
KR101110867B1 (en) Brightness enhancement film with light concentrators
JP3985850B2 (en) Optical sheet and backlight unit and display using the same
US7489373B2 (en) Prism sheet and liquid crystal display having the same
US20020163790A1 (en) Planar light source system and light deflecting device therefor
US20060103777A1 (en) Optical film having a structured surface with rectangular based prisms
JP2009539146A (en) Flexible optical waveguide
KR100951723B1 (en) Optical sheet for back light unit
KR101396001B1 (en) Backlight suitable for display devices
DE60036733T2 (en) Surface lighting device
JP2008527408A (en) Optical film having structured surface with staggered prismatic structure
US20170212295A1 (en) Waveguide illumination system
JP5812566B2 (en) Light capture structure for light emitting applications
US20040246697A1 (en) Area light source and lightguide used therefor
TWI428646B (en) Light guide plate and light emitting apparatus
JP4454020B2 (en) Light source device and light deflection element
US8882323B2 (en) Lightguide
JP2008527632A (en) Optical film having structured surface with concave pyramid-like structure
TWI226495B (en) Light source device
JP2005221619A (en) Optical sheet, back-light, and liquid crystal display device
JPWO2004015330A1 (en) Surface light source device
KR101385796B1 (en) Light-guiding plate, light-guiding plate manufacturing method, surface light-source device, and liquid crystal display device