WO2007125987A1

WO2007125987A1 - Surface-area light source device using light mixing means

Info

Publication number: WO2007125987A1
Application number: PCT/JP2007/059045
Authority: WO
Inventors: Tomoyoshi Yamashita; Yoshiyuki Okamoto; Haruko Ootsuki; Masae Ono
Original assignee: Mitsubishi Rayon Co., Ltd.
Priority date: 2006-04-28
Filing date: 2007-04-26
Publication date: 2007-11-08
Also published as: TW200741311A; JP2007299572A

Abstract

A surface-area light source device having a light guide body (3) having a light entry end surface (31) and a light exit surface (33), a primary light source (1) placed adjacent to the light entry end surface (31), and light mixing means for light emitted from the primary light source (1) and entering into the light entry end surface (31). The light mixing means includes a light control element (2) placed along the light entry end surface (31). The light control element (2) has a first main surface facing the light entry end surface (31) and also has a second main surface on the opposite side of the first main surface. When only the light that is out of light fluxes from the primary light source (1) and advances in the direction less than or equal to 20 degrees relative to the direction normal to the second main surface is made to enter in the second main surface, the light control element (2) causes the amount of light emitted in the direction less than or equal to 20 degrees relative to the direction normal to the first main surface is 50% or less of the light amount when the entire light fluxes from the primary light source (1) is caused to enter in the second main surface.

Description

Specification

Surface light source device using light mixing means

Technical field

The present invention relates to a surface light source device that introduces light emitted from a primary light source into an optical member such as a light guide via a light mixing unit and emits the light from a light emitting surface of the optical member. The surface light source device of the present invention can be used as a backlight of a liquid crystal display device, for example.

Background art

[0002] In recent years, backlights (surface light source devices) for color liquid crystal display devices have been demanded that can provide liquid crystal display images with clearer and better color reproducibility. In the conventional edge light type backlight, a white light emitting light source such as a white light emitting cold cathode tube is used as a primary light source. A light guide having a light incident end surface on which light from the primary light source is incident and a light emitting surface located along a plane crossing the light incident end surface is used. It has been found that a liquid crystal display device using such a conventional edge light type backlight has a problem in the color reproducibility of the liquid crystal display for a color image signal. In particular, the reproducibility of the display color for the R (red) signal is insufficient.

On the other hand, it has become common to use a light-emitting diode (LED) with low power consumption and long life as a primary light source of a backlight of a liquid crystal display device. The LED is a point-like light source, and has been used as a primary light source for a backlight with a small area. In recent years, from the viewpoint of improving the color reproducibility of the above-mentioned color liquid crystal display, it has been proposed to use a combination of three types of LEDs that emit three primary colors of RGB. In this, RGB three primary color light emitting LEDs are arranged in an appropriate order and manner, and the three primary color lights emitted from these LEDs are introduced into the light guide and mixed to obtain white light.

[0004] By the way, in a liquid crystal display device, a backlight having an effective light emitting area as large as possible with the smallest possible outer dimensions is required, and the liquid crystal display screen is arranged so as to approach the effective light emitting area of the knock light. It is required to be as large as possible. However, the above-mentioned RGB three-primary-color LED is used as an edge-light type backlight using a primary light source. When trying to expand the effective light emitting area as close as possible to the outer periphery of the light guide (that is, trying to reduce the width of the so-called frame located outside the effective light emitting area), the following Problems arise. In other words, in the effective light emitting area near the RGB three primary color light emitting LEDs, an emission pattern of unmixed primary color light corresponding to the R GB three primary color light emitting LEDs can be observed. The occurrence of such an unmixed primary color light emission pattern causes a significant decrease in color reproducibility in the peripheral region of the color liquid crystal display screen. Similarly, in the case of a monochrome liquid crystal display that uses only a single color LED as the primary light source, the light emission pattern corresponding to the LED is observed in the effective light emission region near the single color LED. Become. The occurrence of such a light emission pattern causes a partial decrease in luminance, that is, a decrease in luminance uniformity in the peripheral area of the monochrome liquid crystal display screen.

[0005] Japanese Unexamined Patent Application Publication No. 2004-158336 (Patent Document 1) discloses a surface light source in which light of a plurality of colors emitted from a plurality of point light sources is mixed by a color mixing means and introduced into a light guide. An apparatus is disclosed. By such color mixing means, that is, light mixing means, light from a plurality of point primary light sources respectively emitting light of a plurality of different colors, for example, light of three primary colors of R (red), G (green), and B (blue) are mixed. Thus, a desired mixed color such as white light can be obtained.

[0006] In addition, in Utility Model Registration No. 3114195 (Patent Document 2), a light adjustment structure is installed between the light source and the end of the light guide plate, and a plurality of light incident surfaces and light exit surfaces of the light adjustment structure are provided. There is disclosed a backlight module in which a plurality of diffusers are installed and the diffusers are configured by a polygonal pyramidal projecting structure.

[0007] An optical member that has light diffusibility or light convergence that can be obtained only by an edge light type surface light source device and that emits light incident on the light incident surface from a light emitting surface opposite to the light incident surface is used. Even in a direct-type surface light source device in which a primary light source is arranged opposite to the light incident surface of the optical member, the use of a plurality of point-like primary light sources as the primary light source, for example, three types of light emitting each of the three primary colors of RGB LED combinations are being used. Therefore, the light mixing means is useful even in a direct-type surface light source device that uses only an edge light type surface light source device.

Patent Document 1: Japanese Patent Application Laid-Open No. 2004-158336

Patent Document 2: Utility Model Registration No. 3114195 Disclosure of the invention

Problems to be solved by the invention

[0008] However, the color mixing means described in Patent Document 1 is a simple transparent plate-like body, and lights of different colors coming from each point-like primary light source are mixed during light guide inside the plate-like body. It is something to do. For this reason, a long distance is required for good light mixing, and the size of the color mixing means cannot be reduced, and the size of the surface light source device tends to be large.

[0009] Further, Patent Document 2 does not describe the specific content of the polygonal pyramid-shaped protruding structure of the light adjustment structure.

[0010] An object of the present invention is to solve the above technical problems, and in particular, color reproduction using a light mixing means that can mix light emitted from a primary light source power well in a small size region. It is an object of the present invention to provide a surface light source device that enables a display image with good performance or brightness uniformity.

Means for solving the problem

[0011] According to the present invention, as a solution to the above technical problem,

A light guide having a light incident end surface and a light exit surface, a primary light source disposed adjacent to the light incident end surface of the light guide, and a light emitted from the primary light source and incident on the light incident end surface of the light guide. A surface light source device having a light mixing means having a mixing action on light, wherein the light mixing means includes a light control element arranged along the light incident end face.

The light control element has a first main surface facing the light incident end surface and a second main surface opposite to the first main surface.

The light control element causes only light traveling in a direction of an angle of 20 degrees or less to the normal direction of the second main surface of the light flux from the primary light source to be incident on the second main surface. The amount of light emitted from the first main surface in a direction with an angle of 20 degrees or less with respect to the normal direction is 50% or less when all of the light flux from the primary light source is incident on the second main surface. A surface light source device, characterized in that

Is provided.

[0012] In one aspect of the present invention, the light control element causes only light traveling in a direction of an angle of 20 degrees or less with respect to the normal direction to the second main surface among the light flux from the primary light source. When incident, the amount of light emitted from the first main surface in an angle of 20 degrees or less with respect to the normal direction is 40% or less of the amount of light incident on the second main surface.

In one aspect of the present invention, the light control element has only the light traveling from the primary light source traveling in a direction with an angle of 20 degrees or less with respect to the normal direction as the second main surface. The amount of light emitted from the first main surface in the direction of an angle of 20 degrees or more and 80 degrees or less with respect to the normal direction is emitted from the first main surface in the direction of an angle of 20 degrees or less with respect to the normal direction. It will be more than 1 time.

[0014] In one aspect of the present invention, the light control element causes only light that travels in a direction of an angle of 20 degrees or less with respect to the normal direction to the second main surface of the light flux from the primary light source. When incident, the amount of light emitted from the first main surface in a direction with an angle of 20 degrees or more and 80 degrees or less with respect to the normal direction in a certain plane including the normal direction is the normal direction. In contrast, the amount of light emitted in a direction with an angle of 20 degrees or less is 1 or more times.

[0015] In one aspect of the present invention, the light control element causes only light that travels in a direction with an angle of 20 degrees or less with respect to the normal direction to the second main surface of the light flux from the primary light source. When incident, the peak in the luminous intensity distribution with respect to the outgoing angle of the outgoing light from the first main surface is an angle of 10 degrees or more with respect to the normal direction.

[0016] In one aspect of the present invention, the light control element causes only light that travels in a direction with an angle of 20 degrees or less with respect to the normal direction to the second main surface of the light flux from the primary light source. The amount of light emitted from the first main surface when incident is 40% or less of the amount of light incident on the second main surface.

[0017] In one aspect of the present invention, the distance between the light guide and the primary light source is 2 to 15 mm. .

In one aspect of the present invention, a light incident surface that is disposed on a light output surface of the light guide and receives light emitted from the light output surface of the light guide and a light output surface on the opposite side. The light deflection element comprises a plurality of prism rows that extend along the light incident end surface of the light guide and are arranged in parallel to each other on the light incident surface, Each prism row has a first prism surface on which light coming from the light exit surface of the light guide is incident and a second prism surface on which the incident light is internally reflected. [0019] According to the present invention, an optical member having a light incident surface and a light emitting surface opposite to the light incident surface and having a light diffusing property or a light focusing property, A surface provided with a primary light source disposed adjacent to a light incident surface of the optical member, and a light mixing means having a mixing action on light emitted from the primary light source and incident on the light incident surface of the optical member. A light source device,

The light mixing means includes a light control element disposed along the light incident surface, and the light control element includes a first main surface facing the light incident surface and a second main surface opposite to the first main surface. And

Is provided.

[0020] In one aspect of the present invention, the light control element causes only light that travels in a direction of an angle of 20 degrees or less with respect to the normal direction to the second main surface of the light flux from the primary light source. When incident, the amount of light emitted from the first main surface in an angle of 20 degrees or less with respect to the normal direction is 40% or less of the amount of light incident on the second main surface.

[0021] In one aspect of the present invention, the light control element causes only light that travels in a direction of an angle of 20 degrees or less with respect to the normal direction to the second main surface among the light flux from the primary light source. The amount of light emitted from the first main surface in the direction of an angle of 20 degrees or more and 80 degrees or less with respect to the normal direction is emitted from the first main surface in the direction of an angle of 20 degrees or less with respect to the normal direction. It will be more than 1 time.

[0022] In one aspect of the present invention, the light control element causes only light that travels in a direction of an angle of 20 degrees or less with respect to the normal direction to the second main surface of the light flux from the primary light source. When incident, the amount of light emitted from the first main surface in a direction with an angle of 20 degrees or more and 80 degrees or less with respect to the normal direction in a certain plane including the normal direction is the normal direction. In contrast, the amount of light emitted in a direction with an angle of 20 degrees or less is 1 or more times. [0023] In one aspect of the present invention, the light control element causes only light that travels in a direction with an angle of 20 degrees or less with respect to the normal direction to the second main surface of the light flux from the primary light source. When incident, the peak in the luminous intensity distribution with respect to the outgoing angle of the outgoing light from the first main surface is an angle of 10 degrees or more with respect to the normal direction.

In one aspect of the present invention, the light control element has only the light traveling from the primary light source traveling in a direction with an angle of 20 degrees or less with respect to the normal direction as the second main surface. The amount of light emitted from the first main surface when incident is 40% or less of the amount of light incident on the second main surface.

In one embodiment of the present invention, a distance between the optical member and the primary light source is 5 to 6 Omm.

In one aspect of the present invention, a light incident surface that is disposed on a light output surface of the optical member and receives light emitted from the light output surface of the optical member and a light output surface on the opposite side are provided. The light deflection element includes a plurality of prism rows arranged in parallel to each other on the light incident surface or the light exit surface.

Furthermore, in one aspect of the present invention as described above, the light mixing means includes a reflective surface that reflects the return light emitted from the second main surface. In one aspect of the present invention, the light mixing means includes a light diffusing element arranged substantially parallel to the light control element.

[0028] In one aspect of the present invention, at least one of the first main surface and the second main surface includes a fine uneven surface in which a large number of convex cells are arranged, and the convex cells are It consists of a substantially pyramidal surface or a substantially conical surface. In one embodiment of the present invention, the convex cell has an average diameter at the bottom of 10 xm to 4 cm. In one embodiment of the present invention, the convex cell has a height of 3 zm to 3 cm. In one aspect of the present invention, the convex cell includes a substantially triangular pyramid surface having a regular triangular bottom shape, a substantially hexagonal pyramid surface having a regular hexagonal bottom shape, or a substantially quadrangular pyramid having a square bottom shape. It consists of a surface and is arranged so that the bottom part is closely packed. In one aspect of the present invention, the convex cell comprises a substantially triangular pyramidal surface having a side vertex angle of 40 to 110 °. In one embodiment of the present invention, the convex cell comprises a substantially quadrangular pyramid surface having a side surface apex angle of 30 to 80 °. In one embodiment of the present invention, the convex cell Nore consists of a substantially hexagonal pyramid surface with a side apex angle of 30 to 50 °. In one aspect of the present invention, the convex cell has a flat region at the top, and the flat region has an area ratio of 10% or less with respect to the bottom. In one aspect of the present invention, both the first main surface and the second main surface are made of the fine uneven surface. In one aspect of the present invention, the light control element includes a light diffusing agent in the convex cell.

In one embodiment of the present invention, the light control element includes a light diffusing agent.

In one aspect of the present invention, the light mixing means includes a plurality of the light control elements. In one aspect of the present invention, the primary light source is a substantially Lambertian light source having a maximum luminous intensity in the normal direction. In one embodiment of the present invention, the primary light source has a half-width of light intensity distribution of 40 degrees or more and 80 degrees or less. In one aspect of the present invention, the primary light source includes a point light source, and the surface light source device includes a plurality of the point primary light sources. In one aspect of the present invention, the plurality of point-like primary light sources are composed of a plurality of types having different emission colors.

The invention's effect

[0030] According to the surface light source device of the present invention as described above, the light mixing means including the specific light control element is arranged so that the light emitted from the primary light source can be satisfactorily obtained in a small size region. They can be mixed, and display such as a liquid crystal display with good color reproducibility or luminance uniformity is possible.

Brief Description of Drawings

FIG. 1 is a schematic partial sectional view showing an edge light type surface light source device which is one embodiment of a light source device according to the present invention.

2 is a schematic partial plan view of the surface light source device of the embodiment of FIG.

FIG. 3 is a schematic diagram showing an array of point-like primary light sources.

FIG. 4 is a schematic partial perspective view of a light control element.

FIG. 5 is an enlarged view of a second main surface of the light control element.

FIG. 6 is a schematic partial cross-sectional view of a light control element.

FIG. 7 is a schematic diagram of a convex cell of a light control element.

FIG. 8 is a schematic diagram of a convex cell of a light control element. FIG. 9 is a schematic diagram of a convex cell of a light control element.

FIG. 10 is a schematic diagram showing a first light intensity distribution measuring method related to the light control element.

FIG. 11 is a schematic diagram showing a second light intensity distribution measuring method related to the light control element.

FIG. 12 is a schematic diagram for explaining optical characteristics of the light control element.

FIG. 13 is a schematic diagram for explaining optical characteristics of the light control element.

FIG. 14 is a schematic diagram for explaining optical characteristics of the light control element.

FIG. 15 is a schematic diagram for explaining optical characteristics of the light control element.

FIG. 16 is a schematic diagram for explaining a light amount calculation method.

FIG. 17 is a schematic diagram for explaining optical characteristics of the light control element.

FIG. 18 is a schematic diagram for explaining optical characteristics of the light control element.

FIG. 19 is a schematic cross-sectional view of a light guide.

FIG. 20 is a diagram showing a state of light deflection by the light deflection element.

FIG. 21 is a schematic partially cutaway exploded perspective view showing a direct type surface light source device which is one embodiment of a light source device according to the present invention.

22 is a schematic partial exploded cross-sectional view of the surface light source device of the embodiment of FIG.

Explanation of symbols

1 Point primary light source group

1A sealing resin

1R, 1G, IB Point primary light source

2 Light control element

21 First main surface

22 Second main surface

220 Convex cell

221 Bottom

222 Flat top area

2X Light diffusing element

3 Light guide

31 Light incident end face 33 Light exit surface

34 Back side

34a Lens array (prism array)

4 Light deflection element

41 Incident surface

41a prism row

42 Light emitting surface

5, 5 'Light reflecting element

10 Support substrate

11 Radiation fin

6 Plate optical member

61 Light incident surface

62 Light exit surface

7 cases

BEST MODE FOR CARRYING OUT THE INVENTION

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

FIG. 1 is a schematic partial sectional view showing an edge light type surface light source device which is one embodiment of a light source device according to the present invention, and FIG. 2 is a schematic partial plan view of the surface light source device of this embodiment. FIG. As shown in these drawings, in the surface light source device of the present embodiment, one side end surface is a light incident end surface 31, and one main surface substantially orthogonal thereto is a light emitting surface 33. Body 3, the light control element 2 disposed adjacent to the light incident end face 31 of the light guide body 3, and the dot-like structure disposed adjacent to the light control element 2 on the opposite side of the light guide body 3. Primary light source group 1 composed of primary light sources 1R, 1G, and 1B, light deflecting element 4 arranged on the most area of light emitting surface 33 of light guide 3, and light of light guide 3 The light reflecting element 5 disposed opposite to the back surface 34 opposite to the light exit surface 33, and the light reflection disposed on the light exit surface 33 of the light guide 3 on the region near the light incident end surface 31. It is configured to include the element 5 ′.

[0035] The point primary light source 1R is a red light emitting diode (R—LED), the point primary light source 1G is a green light emitting diode (G—LED), and the point primary light source 1B is a blue light emitting diode (B— LED) power. The point primary light sources 1R, 1G, and IB emit divergent light, and are approximately Lambertian light sources that have the maximum luminous intensity in the direction of the normal to the light emitting surface. The half-width at half maximum of the luminous intensity distribution is 40. More than 80 degrees and less than 80 degrees. The dimensions of these point primary light sources in the YZ plane are, for example, 0.3 mm square. These point-like primary light sources are arranged in two rows on the support substrate 10 at appropriate intervals in the Y direction to constitute the point-like primary light source group 1. That is, as shown in Fig. 3, R_LED (1R) and B_LED (1B) are arranged in a line in the Y direction at pitch P1 so that they alternate, and these R-LED and B- G_LED (1G) is placed near the L ED with a distance P2 in the Z direction. That is, G-L ED (1G) is arranged in a line in the Y direction at a pitch PI. In other words, a pair of R-LED (1 R) and G- LED (1G) and a pair of B- LED (1B) and G- LED (1G) are arranged in a line in the Y direction at pitch P1. It is in an arranged form. The arrangement pitch of the point-like primary light sources 1R, 1G, and IB takes into account the target color reproducibility and the degree of luminance uniformity, the frame width described later, and the performance of the light mixing means using the light control element 2. And it can set suitably. The arrangement pitch P1 is 2.8 mm, for example, and the distance P2 is 2 mm, for example. This arrangement compensates for the disadvantage of the G-LED (1G) having lower luminous intensity than the R-LED and B-LED by increasing the density of the G-LED (1G). In addition, color reproducibility in color display such as color liquid crystal display can be improved.

The point-like primary light sources 1R, 1G, 1B are sealed with a sealing resin 1A. The sealing resin 1A has translucency and may contain a light diffusing agent. The width of the sealing resin 1A, that is, the dimension in the Z direction, is substantially the same as the dimension in the Z direction of the light incident end face 31 of the light guide, and is, for example, 5 mm. The surface of the support substrate 10 on which the point-like primary light sources 1R, 1G, and 1B are attached functions as a reflecting surface. The support substrate 10 is provided with heat radiating fins 11 for radiating heat generated when the point-like primary light sources 1R, 1G, and IB are turned on.

FIG. 4 is a schematic partial perspective view of the light control element 2. The light control element 2 has a first main surface 21 facing the light incident end surface 31 of the light guide and a second main surface 22 on the opposite side. The first main surface 21 is a flat surface parallel to the YZ surface. On the other hand, as shown in the enlarged view of FIG. 5, the second main surface 22 is formed of a fine uneven surface in which a large number of convex cells 220 are arranged. The convex cell 220 is formed from a substantially triangular pyramidal surface whose bottom shape parallel to the YZ plane is a triangle such as an equilateral triangle. Thus, a large number of convex cells 220 are arranged so that the bottoms of the respective convex cells 220 are closely packed.

FIG. 6 shows a schematic partial cross-sectional view of the light control element 2. The convex cell 220 has a height (that is, a distance in the X direction from the bottom 221 parallel to the YZ plane) to H, and the average diameter of the bottom 221 is L. Here, the bottom average diameter L is the average value of the maximum diameter and the minimum diameter in a plane parallel to the bottom 221. That is, as shown in FIG. 7, the average value of the diameter Lmax in the direction along one side of the bottom 221 and the diameter Lmin in the direction perpendicular thereto can be used as the bottom average diameter L. Further, as shown in FIG. 7, the side surface apex angle of the convex cell 220 (the apex angle of the triangular shape of the side surface in one side surface) is Φ.

[0039] The bottom average diameter L is preferably 10 to 200 µm. The bottom average diameter L is more preferably 20 to: 100 × m, and particularly preferably 30 to 70 μπι. If the bottom average diameter L is smaller than 10 zm, the production of the convex cell 220 tends to be difficult, and if the bottom average diameter L is larger than 200 βm, the light mixing effect by the convex cell 220 tends to be reduced. . Further, the side apex angle Φ is preferably 40 to 110 °, more preferably 60 to 110 °, and even more preferably 70 to 100 °. If the average apex angle Θ force is outside the range of 0 to 1 10 °, the effect of light mixing by the convex cell 220 tends to decrease. Further, the height H of the convex cell 220 is preferably 3 to 200 / im, more preferably 6 to 100 μm, and particularly preferably 15 to 70 μm.

[0040] As shown in FIG. 8, the convex cell 220 may have a flat region (or curved region) 222 at the top. As a result, the top is damaged. However, in order to reduce the decrease in the effect of light mixing by the convex cell 220, it is preferable that the area ratio of the flat region (or curved region) 222 with respect to the bottom portion 221 is 10% or less.

[0041] The shape of the convex cell 220 does not have to be a substantially triangular pyramid surface as described above. In other words, in the present invention, the shape of the convex cell 220 may be a substantially hexagonal pyramid surface whose bottom is a hexagon such as a regular hexagon as shown in the schematic diagram of FIG. Alternatively, although not shown, the bottom portion may be formed of a substantially quadrangular pyramid surface having a square shape such as a square. Also in these cases, a large number of convex cells 220 can be arranged so that the bottoms of the respective convex cells 220 are closely packed, and the light mixing effect by the convex cells 220 is high. However, When the shape of the convex cell 220 is substantially a quadrangular pyramid surface, the side apex angle φ is preferably 30 to 80 °, more preferably 50 to 80 °, and more preferably 60 to 70 °. More preferably. Further, when the shape of the convex cell 220 is a substantially hexagonal pyramid surface, it is preferably 30 to 40 °, more preferably 30 to 50 °, with respect to the side apex angle φ. . In the present invention, the shape of the convex cell 220 may be another substantially pyramidal surface or substantially conical surface.

[0042] Examples of the material of the light control element 2 include synthetic resin such as glass or acrylic resin. For example, the light control element 2 having a refractive index of about 1.4 to about 1.18 can be used. The thickness of the base of the light control element 2 excluding the height of the convex cell 220 (the dimension in the X direction between the bottom 221 of the convex cell 220 and the first main surface 21) can obtain the required strength. From the viewpoint of reducing the size of the apparatus, for example, a force S within a range of 10 to 500 μm is preferable, a range of 30 to 300 mm 111 is preferable, and a range of 50 to 200 μπι is preferable. More preferably, it is within the range.

As shown in FIG. 1, the light reflecting elements 5 and 5 ′ cover the light control element 2 and the point-like primary light sources 1R, 1G and 1B and the sealing resin 1A from below and above. It extends like so. Accordingly, the light reflecting elements 5 and 5 ′ and the primary light source support substrate 10 cooperate with the light incident end face 31 of the light guide as enclosing members that surround the point-like primary light sources 1R, 1G, IB and the light control element 2. Function. However, the light reflecting elements positioned above and below the point-like primary light sources 1R, 1G, IB and the sealing resin 1A are referred to as the light reflecting elements 5, 5 ′ positioned on the light emitting surface and the back surface of the light guide. It may be formed separately.

[0044] As the light reflecting elements 5, 5 ', for example, a plastic sheet having a metal-deposited reflective layer on the surface can be used, but the light emission luminance of the surface light source device in the vicinity of the light guide light incident end surface 31 is used. In order to further increase the degree of uniformity, a light diffusing and reflecting sheet made by dispersing and mixing light diffusing fine particles such as titanium oxide in a plastic sheet made of polyethylene terephthalate (PET) or the like is used as the light reflecting element 5 or 5 '. It is preferable.

[0045] As described above, the surface (inner surface) of the surrounding member including the light reflecting elements 5, 5 'and the support substrate 10 of the point-like primary light source functions as a reflecting surface. The light mixing means is configured to include the reflecting surface and the light control element 2. Note that, as indicated by phantom lines in FIG. 2, the light mixing means can also be configured including the light diffusing elements 2X arranged substantially in parallel with the light control elements 2. The light diffusing property of the light diffusing element 2X is such that a light diffusing agent, for example, a homopolymer or copolymer such as silicone beads, polystyrene, polymethylol methacrylate, fluorinated metatalylate or the like is mixed in the light diffusing element 2X. The force S can be applied by providing an uneven structure on at least one surface of the light diffusing element 2X. By arranging the light diffusing element 2X, the effect of light mixing can be further enhanced.

[0047] As shown in FIG. 2, the distance between the point-like primary light sources 1R, 1G, 1B and the light incident end face 31 of the light guide is D1, and the light control element 2 and the light guide The distance from the light incident end face 31 is D2. The distance D1 is, for example, 2 to 15 mm, preferably 3 to: 10 mm, more preferably 4 to 6 mm, and the distance D2 is, for example, 0.5 to: 14.5 mm, preferably:! To 10 mm, more preferably 2 to 6mm. By setting the distances D1 and D2 within such a range, it is easy to achieve the effect of the present invention that mixing is favorably performed in a small size region.

[0048] The light control element 2 has the following optical characteristics.

That is, first, as shown in FIG. 10, the light control element 2 and the primary light source (for example, 1B) are arranged so as to have the same positional relationship as in the above embodiment, and the primary light source 1B is turned on. Let At that time, the luminous intensity distribution (first luminous intensity distribution) of the light emitted from the first main surface 21 of the light control element 2 is measured. This luminous intensity distribution is a distribution with respect to the angle Θ with respect to the normal NL of the second main surface 22 of the light control element 2 and passing through the center of the primary light source 1B. Specifically, a photodiode PD as a light receiving element is arranged with respect to the light control element 2 at a distance sufficiently larger than the distance between the light control element 2 and the primary light source 1B. The diode PD is moved so that the angle Θ with respect to the normal NL changes by 90 ° as well as 90 ° as shown. As a result, the first luminous intensity distribution corresponding to the angle Θ in the plane (measurement plane) including the normal NL is obtained.

[0050] Since the distribution may vary depending on how the measurement surface is taken, at least two measurement surfaces (the first measurement surface and the second measurement surface) having different directions with respect to the convex senor 220 are measured. ). Considering the symmetry of the convex cell 220, if the convex cell 220 has a substantially triangular pyramid surface, it is equivalent every time it is rotated 60 ° around the normal NL. Since the measurement surface is obtained, for example, the first measurement surface is the XY plane (see Fig. 4), and the surface is obtained by rotating it by 30 ° or 90 ° around the normal NL in the X direction (for example, the XZ surface) (See Fig. 4) is preferably the second measurement surface. Thus, the first measurement surface is along one side of the bottom of the convex cell 220, and the second measurement surface is orthogonal to the one side of the bottom of the convex cell 220. When the convex cell 220 has a substantially quadrangular pyramid surface, an equivalent measurement surface can be obtained each time it is rotated 90 ° around the normal line NL, so that, for example, the first measurement surface is placed at the bottom of the convex cell. It is preferable that the second measurement surface is a surface along one side and a surface obtained by rotating it 45 ° around the normal NL (a surface that forms 45 ° with one side of the bottom of the convex cell). Les,. In addition, when the convex cell 220 is formed of a substantially hexagonal pyramid surface, an equivalent measurement surface can be obtained each time it is rotated by 60 ° about the normal line NL. Therefore, for example, the first measurement surface is formed of the convex cell. A surface along one side of the bottom and a surface obtained by rotating it by 30 ° or 90 ° about the normal NL (a surface perpendicular to one side of the bottom of the convex cell) is the second measurement surface. Is preferred.

[0051] An average distribution of a plurality of first luminous intensity distributions related to a plurality of measurement surfaces obtained as described above is taken. At that time, the distribution of the region with positive angle Θ and the distribution of region with negative angle Θ are regarded as different distributions with respect to the absolute value of 0 ° to 90 ° of angle Θ, and averaging is performed, and the absolute value of angle Θ Obtain the average distribution (first average distribution) from 0 ° to 90 °.

Next, as shown in FIG. 11, a slit S having a circular opening centered on the normal NL is disposed between the light control element 2 and the primary light source 1B, so that the light from the primary light source 1B Only light (hereinafter referred to as IR) traveling in a direction with an angle of 20 degrees or less with respect to the normal NL of the luminous flux is transmitted to the light control element 2.

20

Incident on the second main surface 22. The luminous intensity distribution at that time (second luminous intensity distribution) is measured in the same manner as the measurement of the first luminous intensity distribution. In the same manner as the measurement of the first luminous intensity distribution, the luminous intensity distributions are measured for a plurality of measurement surfaces, averaged, and the average distribution for the absolute values of the angles Θ of 0 ° to 90 ° (second Average distribution).

[0053] FIG. 12 shows the first luminous intensity distribution P1 and the second luminous intensity distribution on the first measurement surface obtained as described above when the convex cell 220 has a substantially triangular pyramid surface having a side apex angle of 90 °. FIG. 6 is a diagram showing an example of a first luminous intensity distribution P2 on the measurement surface, a second luminous intensity distribution Q1 on the first measurement surface, and a second luminous intensity distribution Q2 on the second measurement surface. This includes the second light intensity distribution measurement on the first measurement surface. The light intensity distribution (incident light intensity distribution on the light control element 2: third light intensity distribution) R corresponding to the angle Θ measured in the same manner with the light control element 2 removed is also shown. The third light intensity distribution measured in the same manner with the light control element 2 removed in the second light intensity distribution measurement on the second measurement surface is the same as the third light intensity distribution R.

[0054] FIG. 13 shows a light intensity distribution corresponding to the angle Θ measured in the same manner in a state where the light control element 2 is removed in the first light intensity distribution measurement on the first measurement surface (to the light control element 2). (Incident light intensity distribution: fourth light intensity distribution) FIG. The fourth luminous intensity distribution measured in the same manner with the light control element 2 removed in the first luminous intensity distribution measurement on the second measurement surface is the same as the fourth luminous intensity distribution S. The luminous intensity value scale in FIG. 13 is the same as that in FIG. This incident luminous intensity distribution S corresponds to the luminous intensity distribution of the point-like primary light source 1B. The primary light source 1B is a substantially Lambertian light source with the maximum luminous intensity in the direction of the normal NL, and the half-value half width of the luminous intensity distribution is not less than 40 degrees and not more than 80 degrees.

FIG. 14 shows the first average distribution Pa with respect to the absolute value 0 ° to 90 ° of the angle Θ obtained by averaging the first luminous intensity distributions P1 and P2, and the second luminous intensity. It is a figure which shows 2nd average distribution Qa regarding absolute value 0 degree-90 degrees of angle (theta) obtained by averaging distribution Q1 and Q2. Here, the third average distribution Ra with respect to the absolute value 0 ° to 90 ° of the angle Θ obtained by averaging the third light intensity distribution R is also shown.

FIG. 15 is a diagram showing a fourth average distribution Sa with respect to absolute values 0 ° to 90 ° of the angle Θ obtained by averaging the fourth light intensity distribution S.

In the present embodiment, only the light traveling from the primary light source 1B that travels in a direction of an angle of 20 degrees or less with respect to the direction of the normal line NL of the second main surface 22 of the light control element 2 is transmitted to the second light source 2B. The amount of light LQm emitted from the first main surface 21 of the light control element 2 in the direction of the normal NL with an angle Θ of 20 degrees or less when incident on the main surface 22 is the luminous flux from the primary light source 1B. Is incident on the second main surface 22 from the first main surface 21 of the light control element 2 with respect to the direction of the normal NL. In the following, it is preferably 30% or less, more preferably 15% or less.

Here, the light amounts LPm and LQm emitted from the first main surface 21 of the light control element 2 in the direction of the angle Θ force ¾0 degrees or less with respect to the direction of the normal NL are the first average distribution described above. Pa and second average Based on the distribution Qa, it can be obtained as follows. That is, here, the average distribution Pa, Q a is set as the luminous intensity distribution f (Θ), and the normal line is perpendicular to the normal line NL and within the first main surface 21 of the light control element 2 as shown in FIG. A polar coordinate system (r, ω) with the position where NL passes as the origin is taken. At that time, the area of the small region Κ between the coordinates (θ, ω) and coordinates (Θ + Δ Θ, ω + Δω) on the spherical surface of the unit radius is Δ Θ · (sin θ) (Δ ω) It becomes. Therefore, the amount of light in this minute region is proportional to f (Θ) · ΔΘ · (sin θ) (Δω). Therefore, the amount of light emitted to a solid angle region with an angle Θ force of ¾0 degrees or less with respect to the direction of the normal NL is the minute region light amount f (θ) · Δ Θ · (sine) (Δ ω). Integrating in the range of 360 degrees and for angle Θ integrated in the range of angle 0-20 degrees, ie

ί ³⁶⁰ ί ² ° ϊ (θ) (8ϊηθ) άθ άω

0 0

= 360 ^2O f (0) (sin0) d0

0

It becomes.

Therefore, the ratio of the light quantity LQm to the light quantity LPm is

[J ^2O Qa (0) (sin0) d0]

0

/ V ² ° Pa (0) (sin0) d0]

0

It becomes.

[0060] When only IR is incident on the second main surface 22, the first main surface 21 of the light control element 2 is used.

20

The amount of light LQm emitted in the direction with an angle Θ of 20 degrees or less with respect to the direction of the normal NL is preferably 40% or less of the amount of light LR incident on the second main surface 22 and more preferably 25% or less. 15

% Or less is more preferable.

Here, the amount of light LR can be obtained based on the third average distribution Ra in the same manner as the case of the amount of light LQm (however, the integration range is the entire region from 0 degrees to 90 degrees).

[0062] Further, when only IR is incident on the second main surface 22, the first main surface 21 of the light control element 2 is used.

20

LQ n is emitted in the direction of angle Θ of 20 degrees or more and 80 degrees or less with respect to the direction of normal NL from 1 to the amount of light LQm emitted in the direction of angle Θ of 20 degrees or less with respect to the direction of normal NL The above is preferred 5 times or more is more preferred 10 times or more is more preferred.

[0063] Here, the light quantity LQn can be obtained based on the second average distribution Qa in the same manner as in the case of the light quantity LQm (however, the integration range is an area of 20 degrees to 80 degrees). [0064] Further, when only IR is incident on the second main surface 22, the emission light from the first main surface 21 is reduced.

20

The peak angle in the luminous intensity distribution (second average distribution Qa) with respect to the emission angle is preferably 10 degrees or more, more preferably 25 degrees or more, and further preferably 40 degrees or more with respect to the direction of the normal NL.

[0065] Further, the light emitted from the first main surface 21 when only IR is incident on the second main surface 22

20

The amount LQs is more preferably 35% or less, more preferably 30% or less, more preferably 40% or less of the amount of light LR incident on the second main surface 22.

[0066] Here, the light quantity LQs can be obtained based on the second average distribution Qa in the same manner as in the case of the light quantity LQm (however, the integration range is the entire region of 0 ° to 90 °).

[0067] The above optical characteristics are defined on the basis of the three-dimensional angular region distribution of the light amount, but the light amount distribution on any one of the measurement surfaces (for example, the first measurement surface or the second measurement surface). It is further preferable that similar optical characteristics can be obtained even when defined based on.

[0068] For example, in the present embodiment, when only IR is incident on the second main surface 22, the method

20

In a certain plane including the direction of the line NL, for example, in the first measurement plane (that is, with respect to the second luminous intensity distribution Q1), the angle Θ is from the first main surface 21 of the light control element 2 to the direction of the normal NL. Amount of light emitted in the direction of 20 degrees or more and 80 degrees or less (the angle Θ of the second luminous intensity distribution Q1 shown in Fig. 12 is proportional to the integral value in the region of 20 degrees to 80 degrees and 20 degrees to 80 degrees) Is the amount of light emitted in the direction where the angle Θ is 20 degrees or less with respect to the direction of the normal NL (the integrated value for the region where the angle Θ of the second luminous intensity distribution Q1 shown in Fig. 12 is -20 degrees to 20 degrees 1) or more, preferably 2 times or more, more preferably 6 times or more.

[0069] By using the light control element 2 having the optical characteristics as described above, it is easy to achieve the effect of the present invention that the light is mixed well in a small size region.

[0070] The above-described examples of the first luminous intensity distributions PI and P2 and the second luminous intensity distributions Ql and Q2 indicate that the second main surface 22 of the light control element 2 is moved from the fine irregular surface of the multiple array of convex cells 220. This is the case. In the present invention, the first main surface 21 of the light control element 2 may be formed of a fine concavo-convex surface of a multi-array of convex cells. FIGS. 17 and 18 show views corresponding to FIGS. 12 and 14 when the same light control element 2 is used in the reverse direction.

[0071] FIG. 17 shows the first luminous intensity distribution P1 'on the first measurement surface and the first luminous intensity distribution on the second measurement surface. An example of the cloth P2 ′, the second light intensity distribution Q1 ′ on the first measurement surface, and the second light intensity distribution Q2 ′ on the second measurement surface is shown. Here, the luminous intensity distribution R is also shown. FIG. 18 shows the first average distribution Pa ′ with respect to the absolute value 0 ° to 90 ° of the angle Θ obtained by averaging the first light intensity distributions P1 ′ and P2 ′, and the second light intensity distribution P1 ′ and P2 ′. The second average distribution Qa 'is shown for the absolute values of 0 ° to 90 ° of the angle Θ obtained by averaging the luminous intensity distributions Q1' and Q2 '. Here, the third average distribution Ra is also shown.

In the present embodiment, only the light traveling from the primary light source 1B that travels in a direction of an angle of 20 degrees or less with respect to the direction of the normal NL of the second main surface 22 of the light control element 2 is transmitted to the second light source 1B. The amount of light LQm 'emitted from the first main surface 21 of the light control element 2 in the direction of the normal NL to the direction of the normal NL when the light enters the main surface 22 is less than 20 degrees is calculated from the primary light source 1B. When all the light beams are incident on the second main surface 22, the amount of light LPm ′ emitted from the first main surface 21 of the light control element 2 in the direction where the angle Θ is 20 degrees or less with respect to the direction of the normal NL 50% or less.

Here, the light amounts LPm ′ and LQm ′ can be obtained in the same manner as the light amounts LPm and LQm based on the first average distribution Pa ′ and the second average distribution Qa ′.

[0074] Further, preferably, when only IR is incident on the second main surface 22, the first of the light control element 2

20

The amount of light LQ m ′ emitted from the principal surface 21 in a direction with an angle Θ force of ¾0 degrees or less with respect to the direction of the normal line NL is 40% or less of the light amount LR incident on the second principal surface 22.

[0075] Preferably, when only IR is incident on the second main surface 22, the first of the light control element 2 is

20

LQn 'is emitted in the direction of angle Θ of 20 degrees or less with respect to the normal NL direction. Light intensity L

It is more than 1 times Qm '.

Here, the light quantity LQn ′ can be obtained based on the second average distribution Qa in the same manner as in the case of the light quantity LQm ′ (however, the integration range is an area of 20 degrees or more and 80 degrees or less).

[0077] In addition, preferably, when only IR is incident on the second main surface 22, the first main surface 21

20

The peak in the luminous intensity distribution (second average distribution Qa ') with respect to the outgoing angle of the outgoing light is at an angle of 10 degrees or more with respect to the direction of the normal NL.

[0078] Preferably, when the IR is incident on the second main surface 22, the light is emitted from the first main surface 21.

20

The amount of light LQs ′ to be emitted is 40% or less of the amount of light LR incident on the second main surface 22. [0079] Here, the light quantity LQs' is obtained on the basis of the second average distribution Qa 'in the same manner as in the case of the light quantity LQm' (however, the integration range is the entire region of 0 degrees or more and 90 degrees or less). it can.

[0080] Preferably, in the present embodiment, when IR is incident on the second main surface 22,

20

In a certain plane including the direction of the normal NL, for example, in the first measurement plane (that is, with respect to the second luminous intensity distribution Q1 ′), from the first main surface 21 of the light control element 2 to the direction of the normal NL The amount of light emitted in the direction where the angle Θ is 20 degrees or more and 80 degrees or less (the angle Θ of the second luminous intensity distribution Q1 'shown in Fig. 17 is about 20 to 80 degrees and -20 to 80 degrees. The amount of light emitted in the direction where the angle Θ is 20 degrees or less with respect to the direction of the normal line NL (the angle Θ of the second light intensity distribution Q1 'shown in Fig. 17 is -20 degrees to 20 degrees) It is more than 1 time (proportional to the integral value for the degree region).

[0081] By using the light control element 2 having the optical characteristics as described above, it is easy to achieve the effect of the present invention that the light is mixed well in a small size region.

In the above description, the B-LED (1B) is used as the primary light source for measuring the luminous intensity distribution for defining the optical characteristics of the light control element 2. However, the present invention is not limited thereto, and R-LED (1R) or G-LED (1G) is used as a primary light source for measuring the light intensity distribution for defining the optical characteristics of the light control element 2. Can be used. It is most preferable that the optical characteristics as described above can be obtained with respect to all types of primary light sources. However, in the present invention, if the optical characteristics as described above are obtained with respect to at least one type of primary light sources, small dimensions are required. It is easy to achieve the effect of the present invention that the light is mixed well in the region.

The light guide 3 is arranged in parallel with the XY plane and has a rectangular plate shape as a whole. The light guide 3 has four side end faces, and one side end face parallel to the YZ plane is used as the light incident end face 31.

[0084] The two main surfaces that are substantially orthogonal to the light incident end surface 31 of the light guide 3 are respectively positioned substantially parallel to the XY plane, and one of the surfaces (the upper surface in the figure) is the light emitting surface 33. Has been. Note that the thickness of the light guide 3 is largest at the end on the light incident end face 31 side, and then gradually decreases with increasing distance from the X direction. That is, the back surface 34 of the light guide is formed with an inclination, and the light guide has a wedge shape in the X direction. This wedge shaped wedge The angle can be, for example, 0.2-3 degrees.

The thickness of the light guide 3 is a force that is appropriately set according to the size of the light emitting surface 33, for example, about 2 to 8 mm in the vicinity of the light incident end surface 31. However, the light guide 3 is not limited to the wedge shape as described above, but may have a uniform overall thickness.

[0086] At least one of the light output surface 33 and the back surface 34 of the light guide 3 has a rough directional light output mechanism, a prism array, a lenticular lens array, a V-shaped groove, and the like. By providing a directional light emitting mechanism, etc., consisting of a lens surface in which the lens array is formed in parallel with the light incident end face 31, the light incident from the light incident end face 31 is guided through the light guide 3. Light having directivity is emitted from the light emitting surface 33 in a plane (XZ plane) orthogonal to both the light incident end surface 31 and the light emitting surface 33. The peak direction (peak light) of the outgoing light intensity distribution in this XZ in-plane distribution is the angle formed by the light outgoing surface 33. The angle a is, for example, 10 to 40 degrees, and the full width at half maximum of the emitted light luminous intensity distribution is, for example, 10 to 40 degrees.

[0087] The rough surface and the lens array formed on the surface of the light guide 3 should have an average inclination angle Θ a in the range of 0.5 to 15 degrees according to IS04287 / 1-1984. It is preferable from the viewpoint of improving the uniformity of the luminance in the interior. The average inclination angle Θa is more preferably in the range of 1 to 12 degrees, and more preferably in the range of 1.5 to 11 degrees.

[0088] The average inclination angle Θ a of the rough surface formed on the light guide 3 is measured according to IS04287 / 1-1984 using a stylus type surface roughness meter, and the coordinates in the measurement direction are determined. The following equation (1) and equation (2) from the obtained gradient function f (X) as X

Aa = (l / L) ί ^L

o I (d / dx) f (x) I dx (1)

Θ a = tan ^_1 (Aa). (2)

Can be obtained using Here, L is the measurement length, and Δa is a tangent of the average inclination angle Θa.

[0089] Further, the light guide 3 preferably has a light emission rate in the range of 0.5 to 5%, more preferably in the range of 1 to 3%. This is because when the light emission rate is smaller than 0.5%, the amount of light emitted from the light guide 3 tends to be small and sufficient luminance cannot be obtained. When the ratio is greater than 5%, a large amount of light is emitted in the vicinity of the primary light source 1, and the attenuation of the emitted light in the X direction within the light emitting surface 33 becomes significant, and the luminance uniformity at the light emitting surface 33 is increased. This is because it tends to decrease. In this way, by setting the light output rate of the light guide 3 to 0.5-5%, the angle of the peak light in the light intensity distribution (in the XZ plane) of the light emitted from the light output surface is the light output. The full width at half maximum of the emitted light intensity distribution (in the XZ plane) in the XZ plane that is in the range of 50 to 80 degrees with respect to the normal of the surface and is perpendicular to both the light incident end face and the light emitting face is 10 to 40 degrees. A light source with a high directivity can emit light with a high directivity from the light guide 3 and its light emitting direction can be efficiently deflected by the light deflecting element 4. Can be provided.

In the present invention, the light emission rate from the light guide 3 is defined as follows. The light intensity (I) of the emitted light at the light incident end surface 31 side edge of the light emitting surface 33 and the light incident end surface 31 side edge

0

The relationship with the emitted light intensity (I) at the distance L is given by the following equation (3), where t is the thickness of the light guide 3 (dimension in the Z direction).

1 = 1/100) [l— / 100)]] ^{L / t} … (3)

0

Satisfying such a relationship. Here, the constant α is the light output rate, and the light guide 3 per unit length (the length corresponding to the light guide thickness t) in the X direction perpendicular to the light incident end surface 31 on the light output surface 33 It is a ratio (percentage:%) at which light is emitted from the light source. This light emission rate _α is obtained from the gradient by plotting the relationship between the logarithm of the light intensity of the light emitted from the light exit surface 23 on the vertical axis and (L / t) on the horizontal axis. be able to.

[0091] In addition, the directivity in the plane parallel to the light incident end face 31 (YZ plane) of the light emitted from the light guide 3 is controlled on the other main surface not provided with the directional light emission mechanism. Therefore, it is preferable to form a lens surface in which a large number of lens rows extending in a direction substantially perpendicular to the light incident end surface 31 (X direction) are arranged. In the present embodiment, a rough surface is formed on the light emitting surface 33, and as shown in FIG. 19, a large number of lenses extending on the back surface 34 in a direction substantially perpendicular to the light incident end surface 31 (X direction). A lens surface is formed by arranging the rows 34a in parallel with each other. In the present invention, contrary to the embodiment shown in FIG. 19, a lens surface may be formed on the light emitting surface 33 and the back surface 34 may be a rough surface.

As shown in FIG. 19, a lens array is formed on the back surface 34 or the light emitting surface 33 of the light guide 3. In this case, the lens array may be a prism array 1J extending substantially in the X direction, a lenticular lens array, a V-shaped groove, or the like, but the YZ cross-sectional shape is preferably a substantially triangular prism array.

[0093] In the present invention, when a prism row is formed as the lens row 34a on the back surface 34 of the light guide 3, the apex angle is preferably in the range of 85 to 110 degrees. This is because by setting the apex angle within this range, the light emitted from the light guide 3 can be collected appropriately, and the luminance as a surface light source device can be improved. Preferably 90-: 100 degree range.

[0094] In the light guide of the present invention, a desired prism array shape is accurately manufactured to obtain stable optical performance, and wear and deformation of the prism top during assembly work and use as a light source device are prevented. For the purpose of suppression, a flat part or a curved part may be formed at the top of the prism row.

In the present invention, light diffusing fine particles are mixed and dispersed in the light guide instead of or in combination with the light emitting surface 33 or the back surface 34 as described above. By doing so, a directional light emitting mechanism may be provided.

The light deflection element 4 is disposed on the light exit surface 33 of the light guide 3. The two main surfaces 41 and 42 of the light deflection element 4 are arranged in parallel with each other as a whole, and are respectively located in parallel with the XY plane. One of the main surfaces 41 and 42 (the main surface located on the light emitting surface 33 side of the light guide 3) is a light incident surface 41, and the other is a light emitting surface. The light exit surface 42 is a flat surface parallel to the light exit surface 33 of the light guide 3. The light incident surface 41 is a prism row forming surface in which a large number of prisms lj41a extending in the Y direction are arranged in parallel to each other. On the prism array forming surface, a flat portion having a relatively narrow width (for example, a flat portion having a width equal to or smaller than the dimension in the X direction of the prism array) may be provided between the prism arrays in contact with P. From the viewpoint of improving the utilization efficiency, it is preferable to arrange the prism rows continuously in the X direction without providing a flat portion. The prism array forming surface may be provided on the light exit surface 42 instead of the light entrance surface 41. Further, the opposite surface of the prism array forming surface may be a diffusing surface provided with minute protrusions instead of a flat surface.

FIG. 20 shows the state of light deflection by the light deflection element 4. This figure shows the light guide in the XZ plane 3 shows the traveling direction of peak light from 3 (light corresponding to the peak of the outgoing light distribution). The peak light obliquely emitted from the light output surface 33 of the light guide 3 at an angle α is incident on the first surface of the prism array 41a, is totally reflected by the second surface, and is substantially in the direction of the normal of the light output surface 42. Exit. Further, in the YZ plane, the luminance in the normal direction of the light exit surface 42 can be sufficiently improved in a wide area by the action of the prism row 34a on the back surface 34 of the light guide as described above.

[0098] The shape of the prism surface of each prism row 41a of the light deflection element 4 is not limited to a single plane, and may be, for example, a convex polygonal shape or a convex curved surface shape. Visualization can be achieved.

[0099] In the light deflection element of the present invention, a desired prism shape is accurately manufactured to obtain stable optical performance, and wear and deformation of the prism top during assembly work and use as a light source device are suppressed. For this purpose, a flat portion or a curved surface portion may be formed at the top of the prism row. In this case, the width of the flat portion or curved surface portion formed on the top of the prism row should be 3 _β m or less to suppress the occurrence of uneven brightness patterns due to the sticking phenomenon if the brightness of the light source device is reduced. From the viewpoint, it is more preferably 2 / m or less, and further preferably 1 μm or less.

[0100] The light guide 3 and the light deflection element 4 can be formed using a synthetic resin having a high light transmittance. Examples of such synthetic resins include methacrylic resins, acrylic resins, polycarbonate resins, polyester resins, and chlorinated resin. In particular, methacrylic resin is optimal because of its high light transmittance, heat resistance, mechanical properties, and molding processability. Such a methacrylic resin is a resin containing methyl methacrylate as a main component, and a methyl methacrylate having a content of 80% by weight or more is preferable. When forming the surface structure such as the rough surface or hairline of the light guide 3, the light deflecting element 4 and the light diffusing element 6 or the surface structure such as the prism array or the lenticular lens array, 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 photo-curable resin. Furthermore, active energy is applied to the surface of a transparent substrate such as a polyester film, an acrylic resin, a polycarbonate resin, a salt bulb resin, a polymethacrylimide resin, or the like. A rough surface structure or a lens array arrangement structure made of a one-line curable resin may be formed, or such a sheet may be bonded and integrated on a separate transparent substrate by a method such as adhesion or fusion. Good. Active energy ray curable resins include polyfunctional (meth) acrylic compounds, vinyl compounds, (meth) acrylic acid esters, aryl compounds, metal salts of (meth) acrylic acid, etc.

[0101] The light emitting surface of the surface light source device including the primary light source 1, the light control element 2, the light guide 3, the light deflection element 4, and the light reflection elements 5, 5 'as described above (light deflection element) By disposing a liquid crystal display element (not shown) on the light exit surface 42), a liquid crystal display device using the surface light source device of the present invention as a backlight is configured. The liquid crystal display device is observed by an observer through the liquid crystal display element from above. The display area of the liquid crystal display device is determined by the display area of the liquid crystal display element or the opening area of the frame that holds the liquid crystal display element.

[0102] In the present embodiment, each of the plurality of point-like primary light sources 1R, 1G, IB is emitted from each of the reflecting surfaces (light reflecting elements 5, 5 'and the point-like primary light source support substrate 10). The light that is reflected by the surface of the surrounding member including the light enters the second main surface 22 of the light control element 2. A part of the light is reflected by the surface of the large number of convex cells 220 constituting the second main surface 22, and the other part is reflected by or not refracted by the surface of the large number of convex cells 220. The light is introduced into the control element 2 and is emitted from the first main surface 21 with or without receiving the refraction action by the first main surface 21. The reflected light reflected by the surface of the convex cell 220 is incident on the second main surface 22 again after being reflected by the reflecting surface. Since the direction of this re-incident light is generally different from the direction of incidence at the time of initial incidence, the light is repeatedly reflected by the second main surface 22 and re-incident on the second main surface 22. Is introduced into the light control element 2. Based on the shape of the convex cell 220, the distribution of the angle of the light emitted from the first principal surface 21 with respect to the normal direction NL is broad for the light from each point-like primary light source 1R, 1G, IB. It becomes. Accordingly, the light of each color emitted from the first main surface 21 is efficiently mixed at a short distance in the X direction, and is sufficiently mixed into white light. In addition, the uniformity of the light distribution depending on the position is improved. Such light mixing is not necessarily limited to what should be done before the light reaches the light guide 3, and after light is introduced into the light guide 3 from the light incident end face 31, Distance (Re, shorter than the width of the picture frame, distance ). For example, in FIG. 1, in the region in the XY plane where the light reflecting element 5 ′ extending in the X direction so as to cover the vicinity of the light incident end surface 31 on the light emitting surface 33 of the light guide is present. It is sufficient that the light mixing is performed. The distance W extending in the X direction on the light guide light exit surface 33 of the light reflecting element 5 ′ is equal to or smaller than the frame width, and the light control element 2 and the light guide light incident end surface 31 are the same. The force that can be set as appropriate according to the distance D2 between and the like, for example, 0.2 to 5 mm.

It should be noted that a part of the light introduced into the light guide 3 may be emitted from the light incident end face 31 and arrive at the light control element 2, but such light is emitted from the light control element 2. Or reflected through the light control element 2 without being refracted or reflected by the reflecting surface in the same manner as described above and used for light mixing in the same manner as described above.

[0104] According to the edge light type surface light source device of the present embodiment as described above, the light mixing means has the second main surface 22 composed of fine concavo-convex surfaces in which a large number of specific-shaped convex cells 220 are arranged. And a reflection surface that reflects the return light from the light control element. Accordingly, among the light emitted from each of the plurality of point-like primary light sources 1R, 1G, and 1B, the component that travels in an oblique direction with respect to the normal direction of the light control element 2 is convex on the second main surface. The main cell can be transmitted. The component incident in the normal direction of the light control element or a direction close thereto is mainly reflected by the convex cell 220 on the second main surface and returned to the direction oblique to the normal direction. be able to. Then, the return light obtained thereby is reflected by the reflecting surface, so that it travels in a different path from the light first emitted from the point-like primary light source, and enters the second main surface 22 of the light control element. It is possible to make S. In addition, even if the size of the light mixing means is small, good light mixing is possible, the distance between the primary light source and the light incident end face of the light guide can be shortened, and even a small frame size is effective. The reduction in color reproducibility and brightness uniformity at the periphery of the light-emitting area can be reduced, and the device can be downsized.

FIG. 21 is a schematic partially cutaway exploded perspective view showing a direct type surface light source device that is one embodiment of the light source device according to the present invention, and FIG. 22 is a schematic view of the surface light source device of the present embodiment. It is a partial exploded sectional view. In these drawings, members having the same functions as in FIGS. 1 to 20 are given the same reference numerals. In this embodiment, as shown in FIGS. 21 and 22, the support substrate 10 that supports the point-like primary light sources 1R, 1G, 1B in a two-dimensional manner is the bottom surface of the box-shaped case 7. Arranged above. The inner surface of the support substrate 10 is preferably a reflecting surface having a high light reflectance. The arrangement of the point-like primary light sources 1R, 1G, and IB can be a plurality of arrangements as described with reference to FIG. 3, and these can be arranged in parallel to each other. Above the point-like primary light sources 1R, 1G, IB, a light control element 2 attached to the support substrate 10 is arranged so as to cover the point-like primary light sources 1R, 1G, 1B.

In the present embodiment, it is particularly preferable that a set of point-like primary light sources 1R, 1G, and IB is arranged corresponding to each convex cell 220. In the present embodiment, the bottom average diameter L of the convex cell 220 is preferably 5 mm to 4 cm. The bottom average diameter L is more preferably 1 to 3 cm, and particularly preferably 1.5 to 2 cm. If the bottom average diameter L is smaller than 5 mm, it tends to be difficult to arrange the point-like primary light sources 1R, 1G, and IB so as to correspond to the convex cells 220. The bottom average diameter L is larger than 4 cm. Then, the effect of light mixing by the convex cell 220 tends to decrease. Further, the side apex angle φ is preferably 40 to 110 °, more preferably 60 to 110 °, and even more preferably 70 to 100 °. When the average apex angle Θ is out of the range of 40 to 110 °, the effect of light mixing by the convex cell 220 tends to decrease. The height H of the convex cell 220 is preferably 4 mm to 3 cm, more preferably 7 mm to 2 cm, and particularly preferably:! To 1.5 cm. The light control element 2 has optical characteristics similar to those of the embodiments of FIGS.

A plate-like optical member 6 attached to the case 7 is arranged above the light control element 2 so as to cover the light control element 2.

The optical member 6 has a light incident surface 61 facing the light control element 2 and a light exit surface 62 on the opposite side, and has light diffusibility or light convergence. Examples of such an optical member 6 include a light diffusing element or a condensing element in which at least one surface is a lens forming surface formed by forming a large number of fine light focusing lens patterns.

[0110] In the present embodiment, similar to the embodiments of Figs. 1 to 20 described above, the light is emitted from each of the plurality of point-like primary light sources 1R, 1G, and IB, and a part thereof is a reflecting surface (the inner surface of the case and the point). Of the surrounding light source including the support substrate 10 of the primary light source. The scattered light is incident on the second main surface 22 of the light control element 2. As in the above embodiments:! To 20, the light of each color emitted from the first main surface 21 is efficiently mixed at a short distance, and is sufficiently mixed into white light. In addition, the uniformity of the light distribution depending on the position is improved.

[0111] In the present embodiment, it is preferable that the light mixing is performed before the light reaches the optical member 6. Therefore, the distance D2 'between the light control element 2 and the optical member 6 is, for example, It is 5 to 50 mm, preferably 10 to 40 mm, and more preferably 15 to 30 mm. Further, the distance D1 ′ between the point-like primary light sources 1R, 1G, 1B and the optical member 6 is, for example, 5 to 60 mm. By making the distances D1 ′ and D2 ′ within such a range, it is easy to achieve the effect of the present invention when mixing is performed well in a small size region.

[0112] In the description of the above-described embodiment, the force in which the second main surface 22 of the light control element 2 is mainly composed of a plurality of fine uneven surfaces of the convex cells 220. In the present invention, the light control element If the optical element 2 has the optical characteristics as described above, the first main surface 21 of the light control element 2 may be composed of a fine concavo-convex surface of a large array of convex cells, or the light control element. Both the first main surface 21 and the second main surface 22 of the second may be formed of a fine uneven surface force of a multi-array of convex cells. In the present invention, the light control element 2 having the optical characteristics as described above may be additionally used, and the plurality of light control elements 2 may be arranged in parallel.

Furthermore, in the present invention, as the light control element 2, an element containing a light diffusing agent inside, particularly in a convex cell can be used. As a result, a better light mixing effect can be obtained.

Example

[0114] Hereinafter, the present invention will be described by way of examples.

[0115] [Example 1]

As described below, eight edge light type surface light source devices [device No. 1-1 to device No. 1-8] belonging to the embodiment described with reference to FIG. 1 and others were manufactured.

[0116] By injection molding using acrylic resin (Ataripet TF8 [trade name] manufactured by Mitsubishi Rayon Co., Ltd.), the light exit surface has a matte surface with an average inclination angle of 3.5 degrees, and the back surface has a prism apex angle. It consists of a number of X-direction prism rows that are 100 degrees, a radius of curvature of the top tip of 15 μm, and a pitch of 50 μm. The X-direction dimensions are 235 mm and the Y-direction dimensions are parallel to each other. Eight wedge-shaped rectangular light guides having a thickness of 5.6 mm at the end on the light incident end face side and l mm at the end on the other side were prepared. A light reflecting film was affixed to an end face other than the light incident end face of each light guide, and a light diffusing and reflecting film was disposed so as to face the back face.

[0117] Eight light control elements were produced by forming an acrylic resin layer with a fine uneven surface on one side of a polyethylene terephthalate (PET) sheet. The fine concavo-convex surface (second main surface) of these light control elements is a close-packed filling of convex cells consisting of a substantially triangular pyramidal surface whose bottom is a regular triangle with a side length of 35 xm. It was. Convex senores on the substantially triangular pyramid surface of each light control element The J-plane apex angle φI was 40 °, 50 °, 60 °, 70 °, 80 °, 90 °, 100 ° and 110 °. Each light control element obtained by force was placed so that the first main surface thereof was opposed to the light incident end surface of the light guide.

[0118] R-LED, G-LED, and B-LED, which are substantially Lambertian light sources as primary light sources, were arranged so as to face the second main surface of each light control element. Here, as shown in FIG. 2, the primary light source was disposed on an aluminum support substrate with a pitch P1 of 2.8 mm and a distance P2 of 2 mm, and covered with a sealing resin. In addition, the light-diffusion reflection film extended from the light-projection surface and back surface of the light guide was arrange | positioned at the upper and lower sides of the primary light source, respectively. The distance D1 shown in Fig. 2 is 5mm, the distance D2 shown in Fig. 2 is 4mm, and the distance W shown in Fig. 1 is lmm.

[0119] Each of the above eight configurations was incorporated into a frame. In these configurations, the maximum peak of the luminous intensity distribution (in the XZ plane) from the light guide was 70 ° with respect to the normal direction of the light emitting surface, and the full width at half maximum was 22.5 °.

[0120] For each light control element, the first light intensity distributions PI and P2 and the second light intensity distributions Ql and Q2 were measured as described with reference to FIGS. Further, the third luminous intensity distribution R and the fourth luminous intensity distribution S were measured. Based on these measurement results, the first to fourth average distributions Pa, Qa, Ra, Sa were obtained. Further, based on these, the light amounts LPm, LQm, LQn, LQs, LR are calculated as described in FIG. 16 and others, and based on these, the following Dl, D2, D3, D4 are calculated. , D5 and D6, the values shown in Table 1 below were obtained.

[0121] D1: Ratio of light quantity LQm to light quantity LPm;

D2: Ratio of light quantity LQm to light quantity LR;

D3: Ratio of light quantity LQn to light quantity LQm;

D4: Peak angle in the second average distribution Qa;

D5: Ratio of light quantity LQs to light quantity LR;

D6: Based on the second luminous intensity distribution Q 1 Θ force against the emitted light quantity in the region of -20 ° to 20 ° based on the second light intensity distribution Q 1 of the emitted light amount in the region of ¾0 ° to 80 ° and 120 ° to 80 ° Ratio [however, the second luminous intensity distribution Q 1 relates to the measurement surface where the maximum emitted light quantity ratio can be obtained].

[0122] On the other hand, a prism array formed by forming a large number of prism arrays with an apex angle of 68 degrees in parallel with a pitch of 50 μm using an acrylic ultraviolet curable resin with a refractive index of 1.5064 has a thickness of 125. Eight prism sheets formed on one surface of a μm polyester film were prepared.

[0123] The obtained prism sheets are arranged such that the prism row forming surface faces the light exit surface (mat surface) of each light guide and the ridge line of the prism row is parallel to the light incident end surface of the light guide. Placed on

[0124] For the surface light source devices No. 1-1 to No. 1-8 manufactured as described above, turn on the R-LED, G-LED and B-LED as the primary light source. When the light emitting surface was visually observed, the emission pattern of each color light corresponding to each light emitting diode in the vicinity of the light guide light incident end surface was not visually recognized, and the entire light emitting surface was white and uniform in brightness. Suddenly.

[0125] [Comparative Example 1]

A surface light source device [device No. 1_9] was produced in the same manner as in Example 1 except that a light-transmitting sheet having smooth surfaces was used in place of the light control element. With respect to the translucent sheet, Dl, D2, D3, D4, D5, and D6 were obtained in the same manner as the light control element of Example 1, and the values shown in Table 1 below were obtained.

[0126] Furthermore, the surface light source device [Device No. 1-10] was used in the same manner as in Example 1 except that the light control element was not used (the air layer was used instead of the light control element). Manufactured. The air layer sheet used in place of the light control element is the same as the light control element of Example 1. In the same manner, Dl, D2, D3, D4, D5, and D6 were obtained, and the values shown in Table 1 below were obtained.

[0127] For the surface light source devices No. 1-9 to No. 1-10 manufactured as described above, the R-LED, G-LED and B-LED as the primary light source are turned on. As a result of visual observation of the light emitting surface, in device No. 1-9, the emission pattern of each color light corresponding to each light emitting diode was visually recognized in the vicinity of the light guide light incident end surface, and in device No. 1_10, Light guide The emission pattern of each color light corresponding to each light emitting diode was clearly seen near the light incident end face.

[0128] [Table 1]

[Example 2]

The fine uneven surface (second main surface) of the light control element is a close-packed filling of convex cells consisting of a substantially quadrangular pyramid with a square shape with a bottom of 30 μm on one side. A surface light source device in the same manner as in Example 1 except that the side apex angle φ force of the convex cell is ¾0 °, 40 °, 50 °, 60 °, 70 ° and 80 °. [Device No. 2-1 to Device No. 2-6] were manufactured.

[0130] For each light control element, D1, D2, D3, D4, D5, and D6 were obtained in the same manner as in Example 1. The values shown in Table 2 below were obtained.

[0131] For the surface light source devices of device No. 2_1 to device No. 2_6 manufactured as described above, the R_LED, G-LED and B-LED as the primary light source are turned on and the light-emitting surface is visually observed. As a result of observation, the emission pattern of each color light corresponding to each light emitting diode in the vicinity of the light guide light incident end face is not visually recognized, and the entire light emitting surface is white and uniform in brightness. [0132] [Table 2]

[0133] [Example 3]

The fine concavo-convex surface (second main surface) of the light control element is a close-packed filling of convex cells consisting of approximately hexagonal pyramid surfaces that are regular hexagons with a bottom shape of 35 μm on one side. The surface light source device [Device No. 3_1 to Device No. 3] was used in the same manner as in Example 1 except that the convex cell had a side apex angle Φ of 30 °, 40 °, and 50 °. 3_3] was manufactured.

For each light control element, Dl, D2, D3, D4, D5, and D6 were obtained in the same manner as in Example 1. The values shown in Table 3 below were obtained.

[0135] With respect to the surface light source devices manufactured as described above from device No. 3—1 to device No. 3—3, the R-LED, G-LED and B-LED as the primary light source were turned on. When the light emitting surface was visually observed, the emission pattern of each color light corresponding to each light emitting diode in the vicinity of the light guide light incident end surface was not visually recognized, and the entire light emitting surface was white and uniform in brightness. Suddenly.

[0136] [Table 3] Device No. 3-1 3-2 3-3

Φ (°) 30 40 50

Dl (%) 1.1 21.2 45.1

D2 {) 0.82 9.40

D3 111.5 9.2 1.4

D4 (°) 31 25 15

D5 (%) 92.7 96.0 95.6

D6 43.4 3.4 0.5

[Example 4]

Except that the light control element is arranged so that the fine uneven surface thereof faces the light guide light incident end surface (that is, the fine uneven surface becomes the first main surface), it is the same as in Example 1. Surface light source devices [Device No. 4_1 to Device No. 4_8] were manufactured.

For each light control element, Dl, D2, D3, D4, D5, and D6 were obtained in the same manner as in Example 1. The values shown in Table 4 below were obtained.

[0139] For the surface light source devices of device No. 4_1 to device No. 4_8 manufactured as described above, the R_LED, G-LED, and B-LED as the primary light source are turned on and the light emitting surface is visually observed. As a result, the emission pattern of each color light corresponding to each light emitting diode was not visually recognized, and the entire light emitting surface was white and uniform in brightness.

[0140] [Table 4] Equipment No. 4-1 4-2 4-3 4-4 4-5 4-6 4-7 4-8

(.) 40 50 60 70 80 90 100 110

Dl (¾) 10.1 0.3 0.5 2.6 1.5 2.4 9.2 36.1

D2 (¾) 7.01 0, 27 0.46 2.39 1.37 2.31 8.55

D3 11.2 325.0 151.9 15.4 26.9 10.0 5.6 1.3

D4 (°) 37 57 69 29 61 61 15 1

D5 (%) 91.5 90.6 77.5 48.6 38.0 25.4 58.9 77.9

D6 3.7 129.2 73.9 5.5 9.1 3.1 1.9 0, 6 [0141] [Example 5]

The fine uneven surface (second main surface) of the light control element is a close-packed filling of convex cells consisting of a substantially quadrangular pyramid with a square shape with a bottom of 30 μm on one side. A surface light source device in the same manner as in Example 4 except that the convex vertex has a side apex angle Φ force of ¾0 °, 40 °, 50 °, 60 °, 70 ° and 80 °. [Device No. 5_1 to Device No. 5-6] were manufactured.

[0142] For each light control element, Dl, D2, D3, D4, D5, and D6 were obtained in the same manner as in Example 1. The values shown in Table 5 below were obtained.

[0143] For the surface light source devices of device No. 5_1 to device No. 5_6 manufactured as described above, the R_LED, G-LED and B-LED as the primary light source are turned on and the light emitting surface is visually observed. As a result, the emission pattern of each color light corresponding to each light emitting diode was not visually recognized, and the entire light emitting surface was white and uniform in brightness.

[0144] [Table 5]

[Example 6]

The fine concavo-convex surface (second main surface) of the light control element is a close-packed filling of convex cells consisting of approximately hexagonal pyramid surfaces that are regular hexagons with a bottom shape of 35 μm on one side. The surface light source device [Device No. 6_1 to Device No. 6] was used in the same manner as in Example 4 except that the convex cell had a side apex angle Φ force of ¾0 °, 40 ° and 50 °. 6_3] was manufactured. For each light control element, Dl, D2, D3, D4, D5, and D6 were obtained in the same manner as in Example 1. The values shown in Table 6 below were obtained.

[0147] For the surface light source devices of devices No. 6-1 to No. 6-3 manufactured as described above, the R_LED, G-LED, and B-LED as the primary light sources are turned on to emit light. As a result, the emission pattern of each color light corresponding to each light emitting diode was not visually recognized, and the entire light emitting surface was white and uniform in brightness.

[0148] [Table 6]

[Example 7]

The direct type surface light source device belonging to the embodiment described with reference to FIG. 21 and others was manufactured as follows.

[0150] By cutting an acrylic resin plate (Mitsubishi Rayon Co., Ltd. Atarilite [trade name]), the bottom shape is a square with a side length of 2 cm, and the side apex angle is φ70 ° and high. A number of translucent square pyramids with a length of lcm were produced. This quadrangular pyramid is spread and bonded to the adhesive surface of a PET sheet that has a vertical dimension of 235 mm, a horizontal dimension of 370 mm, a thickness of 125 zm, and an adhesive on one side so that it is closely packed. Thus, two light control elements were produced. These two light control elements were both placed horizontally with their smooth surfaces facing down. This arrangement Then, one element and the other element were overlapped so as to be shifted from each other by 1 cm vertically and horizontally along the bottom side of the quadrangular pyramid (that is, when viewed in the normal direction of the PET sheet of the light control element, The top of the quadrangular pyramid of one element overlaps the center of gravity of the bottom of the quadrangular pyramid of the other element).

[0151] Below the lower light control element, there are four LED light sources (one R-LED) corresponding to the apex of the quadrangular pyramid of the light control element as a primary light source. And one B-LED and two G-LEDs). Further, a light diffusing plate as a light diffusing optical member was disposed above the upper light control element. The distance D2 'between the lower light control element and the optical member was 57 mm, and the β separation D1' between the primary light sources 1R, 1G, IB and the optical member was 60 mm.

[0152] For the surface light source device manufactured as described above, the R_LED, G one LED, and B- LED as the primary light source were turned on and the light emitting surface (light emitting surface of the light diffusing plate) was visually observed. The emission pattern of each color light corresponding to each light emitting diode was not visually recognized, and the entire light emitting surface was white and uniform brightness.

[Example 8]

As a quadrangular pyramid, the shape of the bottom is a square with a side length of 2 cm, and the side apex angle φ force (Example 8-1), 50 ° (Example 8-2), 60 ° (Example 8-3) A surface light source device was manufactured in the same manner as in Example 7 except that the one at 80 ° (Example 8-4) was used.

[0154] For the surface light source device manufactured as described above, R-LED, G as the primary light source

LED and B— When the LED is turned on and the light emitting surface (light emitting surface of the light diffusing plate) is visually observed, the emission pattern of each color light corresponding to each light emitting diode is not visually recognized, and the entire light emitting surface is white. It was like this.

[0155] [Example 9]

Instead of a quadrangular pyramid, the shape of the bottom is an equilateral triangle with a side length of 3 cm, and the side apex angle φ is 60 ° (Example 9-11), 70 ° (Example 91-2), 80 ° Example 9 1 3), 90 ° (Example 9 1 4) 100 ° (Example 9 _ 5) using a triangular pyramid, two light control elements were fabricated, and the two light control elements Place one element so that it is displaced 1.5cm laterally along one side of the bottom of the triangular pyramid and 8.7mm vertically perpendicular to it. A surface light source device was manufactured in the same manner as Example 7 except that the other element was overlapped.

[0156] Regarding the surface light source device manufactured as described above, R-LED, G as the primary light source

[0157] [Example 10]

In Example 1, one light control element having the same shape was produced for the side apex angle φ of the convex cell having a substantially triangular pyramid surface of 90 °.

[0158] These two light control elements were arranged between the primary light source and the light guide light incident end face so that the smooth surfaces face each other (that is, used in the apparatus No. 1-6 there) A surface light source device was manufactured in the same manner as in Example 1 except that elements similar to the light control elements that were used were additionally arranged so that the smooth surfaces face each other.

[0159] For the surface light source device manufactured as described above, R-LED, G as the primary light source

When the LED and B-LEDs were turned on and the light emitting surface was visually observed, the emission pattern of each color light corresponding to each light emitting diode was not visually recognized, and the entire light emitting surface was white and more uniform in brightness. .

Claims

The scope of the claims

[1] A light guide having a light incident end surface and a light exit surface, a primary light source disposed adjacent to the light incident end surface of the light guide, and light incident on the light guide emitted from the primary light source A surface light source device including a light mixing unit having a mixing effect on light incident on the end surface, the light mixing unit including a light control element disposed along the light incident end surface.

[2] The light control element causes the first light source to emit only light that travels in a direction with an angle of 20 degrees or less with respect to the normal direction out of the light flux from the primary light source. The main surface force of the light source is characterized in that the amount of light emitted in an angle of 20 degrees or less with respect to the normal direction is 40% or less of the amount of light incident on the second main surface. The surface light source device described in 1.

[3] The light control element causes the first light source when only light traveling in a direction of an angle of 20 degrees or less with respect to the normal direction is incident on the second main surface among the light flux from the primary light source. The amount of light emitted in the direction of an angle of 20 degrees or more and 80 degrees or less with respect to the normal direction is greater than or equal to one time the amount of light emitted in a direction of an angle of 20 degrees or less with respect to the normal direction. The surface light source device according to claim 1, wherein:

[4] The light control element causes the normal line when only light that travels in a direction of an angle of 20 degrees or less with respect to the normal direction of the light flux from the primary light source is incident on the second main surface. In a certain plane including the direction, the amount of light emitted from the first main surface in a direction with an angle of 20 degrees to 80 degrees with respect to the normal direction is a direction with an angle of 20 degrees or less with respect to the normal direction 2. The surface light source device according to claim 1, wherein the surface light source device is one or more times the amount of light emitted to the light source.

[5] The light control element causes the first light source when only light traveling in a direction of an angle of 20 degrees or less with respect to the normal direction is incident on the second main surface among the light flux from the primary light source. 2. The surface light source device according to claim 1, wherein a peak in a luminous intensity distribution with respect to an outgoing angle of outgoing light of the principal surface force is an angle of 10 degrees or more with respect to the normal direction.

[6] The light control element causes the first light source to emit only light that travels in a direction of an angle of 20 degrees or less with respect to the normal direction out of the light flux from the primary light source. 2. The surface light source device according to claim 1, wherein the amount of light emitted from the main surface is 40% or less of the amount of light incident on the second main surface.

7. The surface light source device according to claim 1, wherein a distance between the light guide and the primary light source is 2 to 15 mm.

[8] An optical deflection element that is disposed on the light exit surface of the light guide and has a light entrance surface on which light emitted from the light exit surface of the light guide enters and a light exit surface on the opposite side. The light deflection element includes a plurality of prism rows that extend along the light incident end surface of the light guide and are arranged in parallel to each other on the light incident surface. 2. The surface light source device according to claim 1, comprising a first prism surface on which light coming from a light exit surface of the body is incident and a second prism surface on which incident light is reflected on the inner surface.

[9] An optical member having a light incident surface and a light emitting surface opposite to the light incident surface, and having a light diffusing property or a light focusing property; a primary light source disposed adjacent to the light incident surface of the optical member; A surface light source device comprising a light mixing means having a mixing action on light emitted from a primary light source and incident on a light incident surface of the optical member,

The light control element causes only light traveling in a direction of an angle of 20 degrees or less to the normal direction of the second main surface of the light flux from the primary light source to be incident on the second main surface. The amount of light emitted from the first main surface in a direction with an angle of 20 degrees or less with respect to the normal direction, A surface light source device characterized in that it is 50% or less of the total luminous flux from the primary light source when it is incident on the second main surface.

[10] The light control element causes the first light source to emit only light that travels in a direction with an angle of 20 degrees or less with respect to the normal direction out of the light flux from the primary light source. The main surface force of the light source is characterized in that the amount of light emitted in an angle of 20 degrees or less with respect to the normal direction is 40% or less of the amount of light incident on the second main surface. The surface light source device described in 1.

[11] The light control element causes the first light source to emit only light that travels in a direction with an angle of 20 degrees or less with respect to the normal direction out of the light flux from the primary light source. The amount of light emitted in the direction of an angle of 20 degrees or more and 80 degrees or less with respect to the normal direction is greater than or equal to one time the amount of light emitted in a direction of an angle of 20 degrees or less with respect to the normal direction. The surface light source device according to claim 9, wherein:

[12] The light control element causes the normal line when only light traveling in a direction of an angle of 20 degrees or less with respect to the normal direction of the light flux from the primary light source is incident on the second main surface. In a plane including the direction, the amount of light emitted from the first main surface in a direction with an angle of 20 degrees or more and 80 degrees or less with respect to the normal direction is a direction with an angle of 20 degrees or less with respect to the normal direction 10. The surface light source device according to claim 9, wherein the surface light source device is one or more times the amount of light emitted to the light source.

[13] The light control element causes the first light source to emit only light that travels in a direction of an angle of 20 degrees or less with respect to the normal direction out of the light flux from the primary light source. 10. The surface light source device according to claim 9, wherein the peak in the luminous intensity distribution with respect to the outgoing angle of the outgoing light of the principal surface force is an angle of 10 degrees or more with respect to the normal direction.

[14] The light control element causes the first light source to emit only light that travels in a direction with an angle of 20 degrees or less with respect to the normal direction out of the light flux from the primary light source. The surface light source device according to claim 9, wherein the amount of light emitted from the main surface is 40% or less of the amount of light incident on the second main surface.

[15] The distance between the optical member and the primary light source is 5 to 60 mm. The surface light source device according to claim 9.

[16] An optical deflecting element that is disposed on the light emitting surface of the optical member and has a light incident surface on which light emitted from the light emitting surface of the optical member enters and a light emitting surface opposite to the light incident surface. 10. The surface light source device according to claim 9, wherein the light deflection element includes a plurality of prism arrays arranged in parallel to each other on the light incident surface or the light exit surface.

17. The surface light source device according to claim 1, wherein the light mixing unit includes a reflection surface that reflects return light emitted from the second main surface.

18. The surface light source device according to claim 1 or 9, wherein the light mixing means includes a light diffusing element arranged substantially in parallel with the light control element.

[19] At least one of the first main surface and the second main surface is made of a fine uneven surface in which a large number of convex cells are arranged, and the convex cell is made of a substantially pyramidal surface or a substantially conical surface. The surface light source device according to claim 1 or 9, characterized in that.

20. The surface light source device according to claim 19, wherein the convex cell has an average diameter at the bottom of 10 μm to 4 cm.

21. The surface light source device according to claim 19, wherein the convex cell has a height of 3 / im to 3 cm.

[22] The convex cell consists of a substantially triangular pyramidal surface whose bottom shape is a regular triangle, a substantially hexagonal pyramidal surface whose bottom shape is a regular hexagon, or a substantially quadrangular pyramid surface whose bottom shape is a square. 20. The surface light source device according to claim 19, wherein the bottom portions are arranged so as to be closely packed.

23. The surface light source device according to claim 19, wherein the convex cell comprises a substantially triangular pyramid surface having a side apex angle of 40 to 110 degrees.

[24] The surface light source device according to claim 19, wherein the convex cell comprises a substantially quadrangular pyramid surface having a side apex angle of 30 to 80 °.

[25] The surface light source device according to claim 19, wherein the convex cell is formed of a substantially hexagonal pyramid surface having a side apex angle of 30 to 50 °.

26. The surface light source device according to claim 19, wherein the convex cell has a flat area at the top, and the flat area has an area ratio of 10% or less with respect to the bottom.

27. The surface light source device according to claim 19, wherein both the first main surface and the second main surface are made of the fine uneven surface.

28. The surface light source device according to claim 19, wherein the light control element includes a light diffusing agent in the convex cell.

29. The surface light source device according to claim 1, wherein the light control element includes a light diffusing agent therein.

30. The surface light source device according to claim 1, wherein the light mixing means includes a plurality of the light control elements.

31. The surface light source device according to claim 1, wherein the primary light source is a substantially Lambertian light source having a maximum luminous intensity in the normal direction.

[32] The primary light source is characterized in that the half width at half maximum of the luminous intensity distribution is not less than 40 degrees and not more than 80 degrees

30. A surface light source device according to claim 29.

[33] The surface light source device according to claim 1 or 9, wherein the primary light source is a point light source, and the surface light source device includes a plurality of the point primary light sources.

34. The surface light source device according to claim 33, wherein the plurality of point-like primary light sources are made of a plurality of types having different emission colors.