WO1996005466A1

WO1996005466A1 - Planar light source using light diffusing sheet

Info

Publication number: WO1996005466A1
Application number: PCT/JP1995/001608
Authority: WO
Inventors: Michiko Takeuchi; Toshikazu Nishio; Taiji Ishii
Original assignee: Dai Nippon Printing Co., Ltd.
Priority date: 1994-08-12
Filing date: 1995-08-11
Publication date: 1996-02-22

Abstract

A planar light source used as a back light source has a light guide plate (1), a light source member (3), a light diffusing sheet (8), a lens sheet (4) and a transmitting display element (6). The light diffusing sheet (8) comprises a transparent base material not containing particles of a light diffusing agent, the surface of the sheet (8) having fine random recesses and projections (41), this finely recessed and projected surface having a roughness of not less than the wavelength of the light from the light source and not more than 100 νm. The light diffusing sheet is made so that, when a cumulative frequency distribution curve of the height of these fine recesses and projections (41) is drawn by taking a percentage of the cumulative frequency distribution of the height of the fine recesses and projections (41) on a vertical axis and the height of the fine recesses and projections on the horizontal axis, the mentioned curve has a projecting portion curved toward a lower portion of the coordinates with an average value of the heights of the fine recesses and projections larger than a median value thereof. If a surface light source is made in this manner, light of a uniform and high brightness is emitted in a desired angular range alone, and surface emission with no unevenness of brightness in different parts of the plane is obtained.

Description

Akira 钿面 Surface light source using light diffusion sheet

The present invention relates to a surface light source useful for a backlight of a transmissive display device such as a liquid crystal display, a lighting advertisement, a $$ sign, and more particularly to a surface light source using a light diffusion sheet.

Background art

Conventionally, the following are known as surface light sources for backlights used in liquid crystal display devices (LCD) and the like.

As the first method, there is known an edge light system using a flat plate as a light guide: ^; In such a surface light source used for ^ ¾, light is λ! Ί from one or both sides of a transparent light guide composed of a flat plate, and ^: light is guided by total internal reflection inside The light propagates uniformly throughout the light plate, and ~~ of the propagated light is converted to light less than the critical angle by the light scattering plate of the light guide ¾®, and the tfc¾ is emitted from the light guide plate surface ( Japan's National Opening of Japan 55-1 6 2 201).

As the surface light source of the second ^], a lens sheet having ^ on one surface and a smooth surface on the other surface is placed on the surface of the light guide plate of the surface light source of ^; With the separated surface facing up, the expanded tfc¾light is uniformly and isotropically diffused within a desired angle range by using the light focusing action of the lens. No. 201).

Furthermore, said Renzushi - bets, when dispersing the light diffusing agent particles such as T io ₂ used in combination with adefovir extinguishing transparent diffuser extinguishing transparent sheet) formed by the transparent resin, a single, vanishing Ade Using only a transparent diffuser laminated on the light guide (US Patent No.

No. 4,727,067, Japanese Patent Application Laid-Open No. 61-55,684). It is also known that the energy is distributed more heavily within the desired limited angle range, and that the expansion f fe with high uniform isotropy can be obtained within that angle range.

However, among the above-mentioned conventional techniques, in the case where only the light scattering plate is provided on the light guide よう, as in the first method, the emitted light is emitted with respect to the normal direction of the light guide surface. A relatively sharp distribution peaks at an angle of 60 degrees, the brightness increases in the ¾g | direction (front direction), which is considered to be the brightest, and the light energy in the lateral direction has no ίέ ^ at all. , 'The phenomenon of reading was seen.

In the conventional technique such as the second method, when a lenticular lens in which a large number of triangular prism type unit lens portions are arranged on a light emitting surface of a light guide as a lens sheet is used as a ridge layer, The ratio of the light energy emitted within an angle of 30 ° to 60 ° centered on the ^ direction of the output surface is a force that actually becomes smaller, in fact, a part of 2 to 4 cmgg from the end of the light guide plate side Until JLS, even though the brightness was high, the brightness gradually decreased, and the end opposite to the light source was noticeably darker.

In addition, there was a P «¾ ^ that when the fascinating transparent expansion I ^ was used, the light expansion t ^ j particles in the diffusion plate absorbed the light and generated light energy.

Furthermore, it is said that the light adhesion between the lens sheet and the surface of the light guide plate generates an equal thickness interference fringe such as a Newton ring. There was also ¾ ^.

To make these points,

1. As described in Japanese Unexamined Patent Application Publication No. Hei 11-24520 and Japanese Utility Model Application Laid-open No. 6-15008, the light diffusing layer of the light guide ¾® Attempts to correct and equalize the luminance distribution in the light guide by increasing and decreasing the ¾t of the pattern closer to the light source and increasing the distance away from the light source;

2. Attempt to correct and uniform the brightness distribution in the light guide by disposing light sources at two or more locations on the side end of the light guide plate as described in Japanese Patent Application Laid-Open No. 3-93036. , 3. A linear prism array (a prism-type lenticular lens) that partially reflects and partially transmits light on the front or back surface of a light guide plate, as described in Japanese Patent Application Laid-Open No. Sho 62-32226. The angle of the prism surface and the thickness of the light guide plate were changed depending on the location, and an attempt was made to obtain output light having substantially uniform brightness and direction from the entire surface of the light guide plate. In any case, it is difficult to make the brightness uniform completely.For example, the device of the first type has a drawback that the halftone dots of the light-diffusing layer can be seen through when viewed from the light-emitting surface side. In the case of myself 2, there was also a drawback that the space and erasure of the entire optical office were doubled to J¾ ±.

In the case of the above three, the power of the light guide plate becomes complicated, the design and manufacture become extremely difficult, and the dots of the light-spreading layer are completely removed! It is hard to visualize ^

An object of the present invention is to solve the above-mentioned problems ^ s and ^^, and to increase uniformity and high brightness only within a desired angle range without increasing the power, power, and the size of the ^ tm. And ^: to provide a surface light source with no variation in luminance depending on the location in the plane.

Disclosure of the invention

According to the present invention, the object is to provide a transparent base material containing no light particles, having random fine irregularities on the surface, wherein the minute irregularities have a wavelength of light source light of £ Lh or less than Ι Ο μππι. The surface roughness is plotted by plotting the percentage of the cumulative frequency distribution of the height of the minute irregularities on the vertical axis and the height of the minute irregularities on the horizontal axis to form a cumulative ¾ ^^ cloth curve of the height of the minute irregularities. At this time, the segregation number distribution curve becomes a convex curve toward the lower side of the coordinates, and the average value of the height of the small irregularities is attained by a surface light source using a light sheet having a value larger than the intermediate value. Is done.

Top ^: The diffusion sheet is located on at least one side of the side end surface, and is located on the light exit surface of an optical flat plate light guide or a light guide having a cavity, which has an emissive layer on S®. ¾S can be provided.

In addition, the upper sheet has a light source housed therein, a rear wall of the light source, a projection wall for covering an image, and a front window of the lamp house having a window opened in front of the light source. It can also be provided to cover.

When the light guide is formed of a flat plate, the surface of the light guide may be a flat surface having a surface roughness equal to or less than the wavelength of the light from the light source.

On the above-mentioned sheet, a convex or concave single-row sheet or a novel row sheet can be formed. Further, another similar diffusion sheet can be formed on the ¾m sheet.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view showing an example of a type display device using the edge light type surface light source of the present invention.

FIG. 2 is a perspective view showing an example of a transparent device using the direct-type surface light source of the present invention.

FIG. 3 is an explanatory cross-sectional view of an example of the edge light type surface light source of the present invention, showing a case where a group is formed on B of the light diffusion sheet.

FIG. 4 is a perspective view showing an example of a lens sheet used in the present invention.

FIG. 5 is a perspective view showing another example of the lens sheet used in the present invention.

FIG. 6 is a perspective view showing still another example of the lens sheet used in the present invention. FIG. 7 is a perspective view showing another example of the lens sheet used in the present invention.

FIG. 8 is a perspective view showing "^" in the case where the lens sheet used in the present invention is doubled.

Fig. 9 is a cross-sectional view showing that light travels from inside the light guide plate to the outside.

Figure 10 shows that ^ that oozes out of the light guide plate due to the tunnel effect reappears in the lens sheet. It is sectional drawing which shows becoming a traveling wave.

FIG. 11 is a cross-sectional view showing that when the optical rat sheet of the present invention is used, the light traveling from the light guide plate to the outside is partially partially reflected and partially reflected. FIG. 12 is a diagram showing an example of the method for producing an ultraviolet-ray sheet of the present invention.

FIG. 13 is a perspective view showing an example of the light diffusion sheet of the present invention produced by the manufacturing method shown in FIG.

FIG. 14 is a cross-sectional view of a conventional edge light type surface light source without a lens sheet.

FIG. 15 is a perspective view of a conventional edge light type surface light source, showing a case where a lens sheet of a power plane is formed.

FIG. 16 is a cross-sectional view of FIG.

FIG. 17 shows the surface roughness of the longitudinal bow, that is, the depth R of the ^! Valley, taken as the percentage of the cumulative distribution, and the abscissa plots the ^ in the ^ to increase the ^ of the optical sheet according to the present invention. FIG. 7 is a diagram showing a cumulative frequency distribution curve f (R) when the surface roughness, that is, the depth R of the ^ Si valley is taken.

FIG. 18 is a cross-sectional view of a molding die having the characteristics of the cumulative S ^ cloth curve f A (R) of FIG.

FIG. 19 is a cross-sectional view of ^ !! ^ !! having the characteristic of the contributory number distribution curve f B (R) of FIG.

FIG. 20 is a cross-sectional view schematically showing an undercut ^ K formed by aggregates of micro-clustered (spherical) particles of chromium metal when a chrome mat is applied to the roll for use.

FIG. 21 shows the relationship between the height of the light sheet according to the present invention, that is, the light M: the surface roughness of the sheet, and the distribution thereof, with the vertical axis representing the surface roughness, ie, the cumulative height R of the peak. ^ The percentage of the cloth is taken, and the horizontal axis is the surface roughness, that is, the peak height R. FIG. 10 is a diagram showing a case where the cumulative distribution curve ί (R) is convex downward from the cumulative distribution curve, and also satisfies the relationship of average value ≧ intermediate value.

FIG. 22 is a partially enlarged measurement diagram of the optical sheet having the cumulative characteristics of FIG.

FIG. 23 shows the height of the optical sheet according to the present invention, that is, the surface roughness of the optical sheet and the distribution thereof, and the vertical axis represents the surface roughness, that is, the cumulative distribution of the peak height R. In the cumulative frequency distribution curve ί (R) with the percentage taken and the surface roughness on the horizontal axis, that is, the peak height R, the cumulative frequency distribution curve 凸 (R) is convex to the cumulative frequency distribution curve 吓. It is a figure showing the case where it is satisfied.

FIG. 24 is a partially enlarged measurement diagram obtained by stereoscopically viewing ¾g of the light sheet having the cumulative number distribution characteristic of FIG.

FIG. 25 shows the height of the light m sheet according to the present invention, that is, the surface roughness of the light diffusion sheet, and the distribution thereof, and the vertical axis shows the surface roughness, that is, the cumulative sum of the peak height R. The cumulative percentage of the cloth, with the horizontal axis representing the surface roughness, that is, the peak height R, is 2 ^ In the cloth curve f (R), the average value of R StSlfc ^ Cloth curve or "T is a diagram showing the case where it consists of a convex part and a convex part on the upper side.

FIG. 26 is a partially enlarged view 61 of the light sheet having the cumulative ^^ cloth characteristic of FIG.

FIG. 27 shows the ^^ height of the optical sheet according to the present invention, that is, the surface roughness of the optical sheet, and the distribution thereof, and the vertical axis represents the surface roughness, ie, the cumulative distribution of the peak height R. Is a graph showing the case where the cumulative distribution curve f (R) is obtained by taking the percentage of the surface roughness, that is, the peak height R, as the horizontal axis, and the cumulative distribution curve is Ei ^. .

Fig. 28 shows the ridges of a right-angled isosceles triangular section having the cumulative frequency distribution characteristics of Fig. 27. FIG. 7 is a partial enlarged view of 光 g of a light ¾t¾ sheet made in FIG.

FIG. 29 shows the height of the projections of the light diffusion sheet according to the present invention, that is, the surface roughness of the light diffusion sheet, and the distribution t state thereof. ^ In the cumulative ¾ ^ ¾ distribution curve を (R), taking the percentage of the cloth and taking the surface roughness on the horizontal axis, that is, the height R of the peak, the cumulative distribution curve is convex upward to ^^ and It is a figure which shows a case where it is convex and an average value <an intermediate value.

3 0 is a stereoscopic phased partial enlarged measuring ¾ ^ figure of the light diffusing sheet ^ with cumulative ¾¾ number distribution characteristic of FIG. 2 9 ₀

FIG. 31 shows the height of the projections of the light diffusion sheet according to the present invention, that is, the surface roughness of the light diffusion sheet, and the distribution thereof, and the vertical axis represents the surface roughness, ie, the cumulative height R of the peak. In the cumulative distribution curve f (R), where the percentage of the cloth is taken and the horizontal axis is the surface roughness, that is, the height R of the peak, the cumulative distribution curve force << a convex curve downward over the entire area It is a figure showing a case.

FIG. 32 is a partially enlarged measurement diagram in which 3 g of the light diffusion sheet having the cumulative number distribution characteristic of FIG.

FIG. 33 is an angular distribution diagram of emission light luminance of the surface light source of the present invention (（Example 9, mi).

FIG. 34 is an angular distribution diagram of emission light luminance of the surface light source example 8) of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a surface light source according to the present invention and a display device using the same will be described with reference to FIGS.

FIG. 1 shows an edge light type surface light source according to the present invention. In FIG. 1, reference numeral 1 denotes a light guide plate, and the light guide plate 1 is a solid transient flat plate. A light source, for example, a linear light source 3 is provided along a side end surface of the light guide plate 1. Behind the light source 3, a reflector 5 is provided. The light emitted from the light source 3 is either directly or The light enters the light guide plate 1 and is internally reflected, for example, as shown in FIG. 3, or is emitted directly from the light guide plate 1 to the outside. A light emitting layer 2 is provided on the back of the light guide plate 1. The surface of the light guide plate 1 on the side opposite to the ¾¾ * layer 2 is formed as an outgoing surface.

The light sheet 8 is provided in contact with the light exit surface, and the light emitted through the light exit surface travels three times on the light sheet 8. The light that has been applied to the light sheet 8 passes through the oversized display device 6 that has the lens sheet 4 attached. A gap 9 is formed between the light diffusion sheet 8 and the light guide plate 1 and between the light SSI! Sheet 8 and the lens sheet 4. The surface of the sheet 8 facing these gaps 9 is formed with a ^ 41 force, which will be described later. The light guide plate 1 can be hollow instead of being solid. In this case, the surface of the solid light guide plate 1 in contact with the matrix 2 and the output surface are each l-shaped, and the space between them is a rectangular parallelepiped cavity.

In the straight T-plane light source shown in FIG. 2, the light source 3 is a line or a light source and is housed in a lamp house 5. The lamp nose 5 covers the back and sides of the light source 3 and functions as a reflecting surface that reflects light from the light source 3 toward the light sheet 8.

1 and 2, 100 indicates the entire surface light source, and 200 indicates the entire display device.

According to the present invention, 1 is obtained by forming microscopic irregularities (for example, sand texture, satin pattern, etc.) on the entire surface of the light diffusion sheet 8 at random, and the minute irregularities Wavelength Co., Ltd., having a surface roughness of 100 μm or less. When a cumulative curve of the height of the minute irregularities is plotted by plotting the percentage of the height of the minute irregularities on the vertical axis and the height of the minute irregularities on the horizontal axis, the cumulative The ^ number distribution curve is a curve including a convex portion toward the lower side of the coordinates, and the average value of the height of the minute irregularities is larger than the intermediate value.

The light diffusion sheet 8 used in the present invention is formed from a body material. Here, as the ttS material, poly (meth) acrylic acid methyl (here, (meth) acrylic acid Means Acrylic IK means methacrylic acid. The same applies to the following. ), Homo- or copolymers of (meth) acrylates such as poly (meth) acrylate, thermoplastics such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polystyrene, polymethylpentene, etc. Fats and the like are used such as transparent ultraviolet ray or electrocurable resin cross-linked and cured by ultraviolet ray or electricity, transparent glass, transparent ceramics and the like.

Examples of the ultraviolet-curable or electro-curable resin include pre-polymers, oligomers, and z or z or または having a heavy ft unsaturated bond such as a (meth) acryloyl group, a (meth) acryloyloxy group, or an epoxy group therein. * ^ Products obtained by appropriately mixing monomers can be used. Throughout the present specification, (meth) acryloyl is used in the meaning of acryloyl or methacryloyl.

Examples of these prepolymers and oligomers include acrylates such as urethane (meth) acrylate, polyester (meth) acrylate, and epoxy (meth) acrylate, and unsaturated polyesters.

Examples of the monomer include dipentaerythritol pentyl (meth) acrylate, trimethylolpropanetri (meth) acrylate, and the like.

It is important that these materials do not contain any optical ffitfciJ particles, unlike ordinary optical fcS (US Pat. No. 4,729,067).

In the case of the light diffusion sheet 8 for an edge light type surface light source, the above 3 ^ ¾§ material usually has a thickness of 5 to 200 // m¾g.

Further, when used for a direct-type surface light source, the light diffusion sheet 8 itself supports its own weight and external force.

Further, the light emitting sheet 8 may have a single-layer configuration as shown in FIG. 1, a two-layer configuration as shown in FIG. 13, or a multilayer configuration having three layers and Lh. The height of the surface of the above light sheet 8 is less than the wavelength of the light source light J¾ ±, 100 // m 41 formed by small irregularities can be directly formed on the surface of ^ fettS material by embossing by hot pressing, sand blasting, etc., or can be manufactured by It is also possible to form a material layer having a projection 41 on the surface. Specifically, Japanese Patent

No. 169005, U.S. Pat.No. 4,576,850 and the like, and a roll film disclosed in U.S. Pat. Use the method of ^^ Ι for ^ 41 on the surface of.

The light 41 formed on the light diffusion sheet 8 not only diffuses the light conversion isotropically, but also between the light diffusion sheet 8 and the smooth flat surface 10 of the light guide plate 1 as shown in FIG. The object is to form at least a gap 9 (dimension ΔΧ) of the wavelength of the light source light between the flat smooth surface 7 of the lens sheet 4 and the sheet 8. If the gap is full of light from the light source, the total reflection power of the light guide plate 1 on the flat surface 10 will not be sufficient, and the height of the unevenness due to ¾ £ 4 1 will exceed 100 m. In this case, the uneven shape of the projection 41 becomes conspicuous, which is inconvenient.

As long as the above-mentioned target power is achieved, ¾g41 can be any unevenness, but it is most important in terms of obtaining a uniform brightness angle ft ^ within the desired diffusion angle and a uniform brightness distribution within the light 21®. In a preferred embodiment, the surface of the light emitting sheet 8 is provided with random fine irregularities (for example, sand texture, satin pattern, etc.) on the entire surface, and the minute irregularities are generated at a wavelength of 100 m of the light source light. The surface roughness is as follows. Typically, as shown in Fig. 31, the vertical distribution is the percentage of the height of the fine irregularities and the horizontal axis is the cumulative distribution curve of the height of the fine irregularities. , The cumulative number distribution curve force becomes a curve including a downwardly convex portion of the coordinates, and the average value of the heights of the minute irregularities becomes larger than the intermediate value. It was formed as follows.

In this way, as shown in FIG. 3, the light L 1, L 2 S, etc., which is λ! Ί out of the light diffusion sheet 8, also act as the To spread, The incident light has a uniform angular distribution, and a high quality and high brightness surface light source can be obtained without any noticeable halftone dot pattern.

Further, the shape of the group 41 may be such that the concave portion becomes narrower toward the bottom of the valley as shown in FIGS. 22 and 24, or as shown in FIG. 18 and FIG. preferable. For example, the cross section of the Wei group 41 is a sinusoidal curve, a cycloid curve, etc., in which the periodic amplitude is randomly changed in each cycle, or a cross-sectional curve with a random and narrow valley by sandblasting, mill engraving, or the like. Then, minute irregularities are formed so that the depth and the distance between adjacent convex portions are equal to or more than the wavelength of the light source light and equal to or less than 100 m, and satisfy the above-mentioned cumulative frequency distribution condition. Such a shape is represented by ^ F from the point of uniformity of the angular distribution of transmitted light, high transmittance, and the point of total reflection at the interface between the light guide plate surface and the light sheet. is there.

Further, such an occupation is indispensable when the SSii method is employed in which the hardening is performed and the hardening is performed, as in the method disclosed in Japanese Patent Laid-Open No. 5-169015. In other words, if the concave part is wide, the power becomes ^^ from ^ !!, or it becomes * ϋ.

As a method for forming the light ¾f [sheet 8, for example, method, heat press method

(Japanese Patent Application Laid-Open No. 56-1577310 discloses a method of embossing a UV-curable thermoplastic resin film with a roll embossing plate, and then irradiating UV rays to cure the film ( Japanese Patent Application Laid-Open No. 61-15663 / 73 discloses that a roller or a roller engraved with a lens shape is coated with an ultraviolet or electro-curable resin, filled into a concave portion, and then passed through the resin. The roll ^: is coated with a transparent substrate film and irradiated with ultraviolet light from the back of the film, or the resin is cured by irradiating ultraviolet rays etc. after transferring 1® to the transparent substrate film, and the cured resin and A method in which the substrate film to which it is adhered is rolled from the roll ^ !! and the lens dish of the roll ^! Is formed into a cured resin layer (Japanese Patent Application Laid-Open No. 5-169015, US Patent No. 4 5 7 6 8 5 0) etc. Can be.

The lens sheet 4 used in the present invention is, for example, as shown in FIG. 4, in which unit lenses 42 of a prism body are arranged with the direction thereof being ^, || (Lenticular lens) or a hemispherical surface as shown in Fig. 5

A two-lens array sheet, a so-called bank eye lens, is used.

Here, the cross-sectional shape of the unit lens 42 may be a continuous, smooth curve such as a circle, an ellipse, a cardioid, an egg shape of Rankin, a cycloid, or an involute curve, or a polygon such as a triangle, a square, or a hexagon. Part or all of the square is used.

These unit lenses may be convex lenses as shown in FIG. 6 or concave lenses as shown in FIG. Of these, preferred are ease of design, manufacture, low light characteristics (half-value angle, luminance peak generated in the sidelobe light direction), isotropic half-angle luminance, ί¾ϋ direction. From the viewpoint of the brightness). In particular, an elliptic cylinder having the long axis in the normal direction of the surface light source is preferable because of its high luminance.

These lens sheets can be used in an lti composition, but in order to control the light diffusion angle in two directions (± down, left and right) using a columnar lens, two lenses as shown in Fig. 8 are used. The sheet may be ¾S so that the, is S¾. In this case, the orientation of the lens is the same as shown in Fig. 8 and the two lenses are oriented in the same direction. '^! Transient or K is the best, but ^ υϋ The lenses of each lens sheet face each other ( The lens may be sandwiched between two lens sheets.

The lens sheet 4 is formed from a ¾¾S material. Here, as the ^: ¾S material, the same material as the light diffusion sheet 8 described above can be used. Normally, a thermoplastic resin such as acrylic or polycarbonate, or a UV- or electrocurable (meth) acrylate acrylate is used.

The above ^: ½¾ material is usually 20 ~ 1 OO

And

^: The higher the property required for the base material, the better, the most desirable is the opacity. However, when used as a lens sheet, depending on the application, it may be feS bright, bran translucent, or gloss translucent. .

Here, the extinguishing transparency refers to a property that makes light substantially uniform in all directions within a semi-solid angle, and is used as a synonym for light isotropic diffusion. In other words, the extinction transparency means the transmission when the f beam is changed from ί® to λ! Ί (Λ ί angle i = O ^e ), when the angle between the transparent ½s surface and the ^ direction is ø. The angular distribution of light ¾ ^ I ^G .Θ) is represented by the following c 0 s distribution,

1 ° (= de _m- cos-90. ≤0≤9 Ο ^β

(Where 0 is the angle between '^ 、 and I ⁰ _mp is the direction ¾ @ light)

Or, a distribution that is similar to that.

As the light guide plate or light guide used in the present invention, either a flat plate made of a transparent material or a flat plate made of a transparent material having a body cavity can be used. In order to make the light source light evenly distributed throughout the light guide using the total internal reflection inside the light guide, and to support the light diffusion sheet 8 It is preferred to use a plate of material.

For the above reasons, the present invention uses the light guide plate 1 (FIG. 1) made of a flat plate made of a transparent material. The opposite surface 10 of the light guide plate 1 opposite to the light scattering reflector is a flat surface and has a surface roughness less than the wavelength of the light source light. The surface roughness referred to in this specification is not the average value of the Wei group (unevenness) but is evaluated by the average value of the difference between the peak and the valley bottom of the 5¾g group. For example, JI SB-0601 or It is measured by the ten-point average roughness Rz of ISO standard. Usually, the light from the light source is acceptable and its wavelength is 0.4 to 0.8; um, so the surface roughness should be 0.4 um or less. Also, the distance between the convex portions is evaluated by an average value such as the average interval Sm of irregularities of the IS0 standard. As a method to increase or decrease the roughness of the surface, a method of ^, for example, heat pressing on the master plate, injection using a mirror-like shape, (casting) swelling, lens precision, etc. Use polishing, etc., ₀

The material of the light guide plate 1 is selected from the same δ¾ materials as those of the above-mentioned lens sheet. Usually, an acrylic resin having a thickness of 1 to 1 OmmSS is used such as a polycarbonate resin plate.

As the light source 3 used in the present invention, a linear light source such as a fluorescent lamp is preferable from the viewpoint of obtaining uniform luminance over the entire surface. However, a light source such as an incandescent lamp can also be used. The light source 3 is provided separately from the side end of the light guide plate 1 as shown in FIG. 1, and a through hole is provided at the side end of the light guide plate 1 or a part of the side end is provided. It is also possible to provide a notch so that part or all of the light source can be inserted into the light guide plate.

Another light source 3 ′ (not shown) can be provided at the other side end of the light guide plate 1 in order to improve the luminance and improve the distribution of the luminance in the plane. The number of these light sources may be one as shown in FIG. 1 or two or more as shown in FIG. Of course, the edge light type surface light source as shown in Fig. 1 may be used to place the light source on the side edge of 2m2U:

As the reflecting mirror 5, a known member, for example, a member such as a parabolic column, a hyperbolic column, an elliptic column, or the like, or a metal thin film provided on a recessed inner surface of a plate or the like by vapor deposition or plating is used.

On the smooth plane 10 of the light guide plate 1, the above-mentioned light sheet 8 is laminated, and on the light sheet 8, the lens sheet 4 is coated. At that time, as shown in FIG. 3, the lens of the lens sheet 4 faces outward (opposite the plane 10), and the smooth surface 7 of the lens sheet 4 faces the ^ group 41 of the optical sheet 8. By mounting, the wavelength of the light source light; the gap 9 of I between the smooth surface 7 of the lens sheet 4 and the light sheet 8 and / or the smooth surface 10 of the light guide plate 1 and the weir group 41 of the light diffusion sheet 8 Is at least part of Allow for minutes.

The area ratio K of the void portion 9, that is,

Κ = (wavelength; Ih, the entire surface of the light guide plate with a gap at h, XI 00% depends on the uniformity of the required in-plane distribution of brightness H 輝度, the light energy use efficiency, and the light guide plate dimension i ^ The determined force, typically the ratio K will be 80% KUi, more preferably 90% Ri: force.

The reason for this is that, as a result of the experiment, as shown in Fig. 16, when both the surface roughness force and the smooth light guide plate surface 10 At the distance y from the side end, most of the input light from the line light source 3 is emitted to the other side end without reflection at all, and the luminance decreases sharply at the part y. Because it turned out to be dark.

Then, as a result of actual measurement, J »> with respect to the length y of the above-mentioned ^: part and the total length Y of the light guide plate 1 in the light propagation direction (FIG. 15), that is, (y / Y) X 100 (%) is 10 to 20 %.

Therefore, in order to distribute the amount of light energy incident on the light guide plate plane 10 from the light source 3 evenly over the entire length Y, it is inevitable that 10 to 20% of the Λί light to the plane 10 will be ^ The remaining 90-80% had to be totally reflected.

Generally,

(Total reflection ¾≤ΖTotal Λί X100%

= (Area of the part with the gap of the wavelength Ζthe entire surface of the light guide plate ®) X I 00 (%) = Κ

Therefore, Κ must be 80-90% i :, and ^ in the previous section was derived.

The light reflection layer 2 used in the present invention is a layer having a performance of causing light to be emitted by ffcS, and can be configured as follows. ① Light guide ¾ On one side of the surface, a pigment with high concealment and high whiteness, such as titanium dioxide or aluminum, is dispersed to form a white powder by painting.

(2) Sandblasting (¾) The uneven surface of the light guide plate on which the unevenness has been formed by embossing is embossed, etc., and then is subjected to evaporation or plating to form a metal thin film of aluminum, chromium, silver, etc. 餍.

(3) Form a metal thin film layer by evaporation or the like on white fe®, which has low concealment properties, formed on the matte surface with the same method.

減衰 Attenuation of 点 B from the light source 3 may be corrected by forming a halftone dot-shaped white layer and decreasing the white portion as the distance from the light source increases.

Although the description has been made mainly on the case of the edge light type surface light source, the combination of the light sheet and the lens sheet according to the present invention can be used for the direct type surface light source as shown in FIG. Further, two optical sheets 8 according to the present invention can be used by laminating J¾ ±. Further, if the required light Δtfcft (half-value angle or the like) may be wide enough, the surface light source may be constituted by only one light diffusion sheet 8 of the present invention or a multilayered light diffusion sheet 8. .

As shown in Fig. 14, the working mechanism of the edge light type surface light source is that the light source 3 enters the light guide plate 1 by λ! Since the incident L 1 has a small Λ ί angle (the angle between the normal to the surface 10) and the critical angle, it is emitted as light LIT, which is a fraction of the power of the incident fi. As a result, emitted light near the light 2¾S is formed. On the other hand, L2 that directly λ! Ί relatively far from the light source 3 has a large λ! Ί angle and a critical angle J¾ ±, so it is not emitted to the outside and becomes totally reflected light L2R. The light is sent to a distant place and is reflected by the male (disturbed) reflected light L

Become 2 S and proceed in all directions. Some of these are λ! へ to the surface 10 below the critical angle, and some of them are emitted light. According to such a principle, the emitted light is formed at a portion away from the light source 3. Here, FIG. 16 shows a state in which the smooth surface 7 of the lens sheet 4, which is a non-lens smooth surface, is laminated on the smooth surface 10 of the light guide plate 1 in a direction in contact with the surface 10. It is shown. Usually, the refractive index of the active materials is about 1.5, and the difference between them is not large. Therefore, although there is a difference of ¾Jg, the lens sheet 4 and the light guide plate 1 are almost optically as shown in FIG. Then, since the surface of the unit lens 4 2 of the lens sheet 4 has a surface with respect to the smooth plane 10, most of ^ S incident on the light guide plate near the light 2¾5, for example, L 1, L 2, L 3 is Since the light is incident at less than the critical angle, some of the light is emitted as it is, and most of the reflected light is returned to the direction of the light source and does not propagate far. Of course, the light that directly enters the lens at a distance from the light source and emits light from there is, for example, a force that also contains L 4 in FIG.

Therefore, as described above, most of the light emitted from the surface light source is concentrated near the light source side, that is, at a position of 10 to 20% of the entire light guide plate.

On the other hand, according to the present invention, as shown in FIG. 1, wei groups 41 are formed on the surface of the light diffusing sheet 8, whereby the light guide plate 1 has at least a partial area between the smooth plane 10 and the lens sheet 4. Then, a void 9 is formed.

Since the gap 9 is usually adjacent to the light guide plate 1 having a refractive index of 1.5 ¾, the air layer (or true) having a refractive index of 1.0 and the surface 10 as an interface, FIG. Total reflection of light occurs as in the case of. Therefore, as shown in FIG. 3, in the region near the light source 3, the emitted light is illuminated by the light beam LIT that is λ! After being totally reflected at the interface of the cavity 9, the emitted light is obtained by L 2 T of less than the critical angle in the irradiating with the expanded icR in the light-spreading IfcS emitting layer 2.

Of course, among L 2 T, some of the light that has been applied to the ¾g group 41 and the plane 10 with the force and the '! is there. Void As described above, when the transmittance ratio K is 80 to 90, the luminance distribution becomes substantially uniform over the entire surface.

Moreover, in the present invention, the height of the surface 41 (that is, the gap 9) is set to the wavelength of the light source light;

The reason is that, as shown in FIG. 9, when ^ SL 1 incident on the smooth plane 10 of the light guide plate 1 from the inside of the light guide plate 1 becomes all reflected light L 1 R, strictly speaking, the light The electromagnetic field does not exist at all in the void 9 (or in the vacuum), but rather exists in the form of “^ the electromagnetic field LIV force transmitted through the interface 10 due to the tunnel effect. However, this electromagnetic field 1 V attenuates exponentially, the amplitude becomes 0 on the order of the wavelength of light, and returns to the light guide plate 1 side.

Therefore, if the gap 9 is far enough apart from the wavelength of light, ^ HLl does not enter the lens sheet 4 from the gap 9 at all.

By the way, as shown in FIG. 10, when the lens sheet 4 having substantially the same refractive index as the light guide plate 1 is applied to the surface 10 of the light guide plate by a beam X≥i5 smaller than the wavelength of light, (Δ Χ However, the above-mentioned electromagnetic field LIV enters the lens sheet 4 without being completely reduced, and becomes a traveling wave again and is subjected to ¾1 light L 1 T force.

In the present invention, since ¾S41 force is formed on the surface of the light sheet 8, between the light guide plate 1 and the light diffusion sheet 8, as shown in FIG. Between the lens sheet 4 and the lens sheet 4, there is formed a region having a gap 9 and a region where there is no gap 9 and the two are optically integrated (or the gap is filled with light even if it is a guest). Of these, the total reflection power of the incident light occurs in a part of the cavity 9, and λ! Ί light is ¾1 in the part of the cavity 9. As described above, the ratio of ^ !: which is totally reflected by the surface 10 is determined by the ratio of the area of the certain portion of the void 9 to the total area of the light guide 扳 1. Thus, according to the present invention, light energy can be used efficiently, and a uniform and high-luminance surface light source can be obtained. Next, with regard to the optical sheet 8 of the present invention, the characteristics of various kinds of ^ 41 obtained by changing the conditions of the roll ^ will be described in Examples 1 to 6 of H. Production examples, surface light sources using them, examples of display devices using the surface light sources, and examples of it will be described with reference to FIG.

(Process of light sheet 8)

Although it has already been described that the light diffusion sheet 8 having 5¾S41 must be peeled off from the roll, it is necessary to peel off the cured resin layer from the mold in order to remove the mold M from the mold M. The shape can be expanded or undercut as shown in Figs. 18 and 19.

It is necessary to make the recess without (overhang), and the shape with the under force 50 as shown in Fig. 20 is ¾tST.

In the production of the light diffusion sheet 8, the conditions for satisfying both the light δ || characteristic and the suitability of the light OT ^ 8 are as follows: in addition to the above-mentioned ^ concavity, there is no middle spread or undercut. The distribution of the number of jobs on the surface roughness is also important. That is, with a surface roughness measuring device such as an electro-needle type or a light ^; The reverse relationship is obtained) The statistics of the depth of the valley (concave) of the surface (the height of the peak of the 山 g portion of the S! Resin) are taken, and the surface roughness is plotted on the vertical axis as shown in Fig. 17, ^ Valley depth R Cumulative ^^ Take the percentage of cloth, the horizontal axis is roughness, ie ^! When the cumulative function f (R) curve represented by the following equation (1) is drawn by taking the depth R of the valley of! If the rising force is gradual and convex downward as in the curve f B (R) of Fig. 7, the ¾i property of ^ is good, and such a curve is obtained in the present invention. It was designed as follows.

Guang R

f (R) = P (x) d x (1)

X = 0 (Where P (x) is the probability density function of surface roughness R)

The cross section of the mold in the case of a function that forms a downwardly convex curve with a gentle rising slope like the curve f B (R) in Fig. 17 is schematically exaggerated. For example, the shape as shown in FIG. 19 is obtained, and the shape of the mold 41 having such characteristics is similar to that of the fB (R) mold with the cumulative distribution curve of the height. O

On the other hand, if the rising force is steep and the curve is convex upward as shown by the curve f A (R) in Fig. 17, the characteristics of ^ と are poor.

A mold having characteristics represented by a function such as a curve f A (R) has, for example, a shape as shown in FIG.

As shown in Figure 20, ^! As described above, it is not suitable for the purpose of the present invention because the undercut shape, in which the concave portion is cut downward toward the bottom, is not suitable for the purpose of the present invention because the protrusion 41 or TffiSi is not formed.

It was found that if the mat mat surface composed of aggregates of micro-dense (spherical) particles of a metal such as chromium was provided in the concave ¾5®, the cross-section as shown in Fig. 20 would result in poor ¾Ι properties.

As already mentioned, the distribution curve of the number of employees with a height of Wei 41 is the curve f が in Figure 17

As shown in (R), when the cumulative ¾ is convex downward in the entire range from 0% to 100%, good properties are given. However, even if a part of the cumulative distribution curve has an upward convex part, the point where the cumulative ¾¾¾ ^ cloth of the cumulative curve becomes 50% (that is, the point corresponding to the average value) is in the middle of the height. When passing on the right side of the value, that is,

Mean ^ median

Then, when turning the cured resin layer from the concave part, it was confirmed by experiments that a sufficiently good wakefulness could be obtained.

In addition, the height of ¾g41, that is, the measurement and data of the surface roughness of the light diffusion sheet 8 The analysis was performed using a surf coder SE-30K manufactured by Kosaka Laboratories Co., Ltd. as a measuring instrument, with a feed rate of 0.2 imnZ s and a measurement length of l mm.

(HM example 1)

The light diffusing sheet 8 shown in FIG. 13 was crimped by the following steps using the apparatus shown in FIG.

(1) A take-up roll 11 of a 50-m thick femless biaxially stretched polyethylene terephthalate base film was prepared.

(2) A roll mold in which a concave portion 15 is engraved randomly by sandblasting of # 80 so that the ten-point average roughness Rz of JIS-B-0601 is 38 / zm on the surface of a metal cylinder. The UV curable resin 16 was supplied to the US® from the T-die nozzle 21 while rotating it, and the surface concave portion of the silicon layer 14 was filled and coated.

③ Next, the above-mentioned material film 12 is unwound from the take-up roll 11 at a speed synchronized with the rotation of the roll ^ l 4, and the base film is rolled on the roll ^! With the fat interposed between the layers, the mercury lamp 23,

Ultraviolet rays were irradiated from the back side of the base film 12 using 23, and the resin was cross-linked and cured in the concave portion of the surface of the roll 14 and simultaneously adhered to the base film 12.

Next, the base film 12 running using the peeling roll 18 was peeled off together with the hardened resin in the form of Group 41 adhered to the base film 12 to obtain a light sheet 8. The light diffusion sheet 8 was wound up as it was, and then cut to a desired size according to and used.

The ultraviolet-curable resin used in this step is obtained by adding a polyfunctional polyester acrylate oligomer to ^ and adding a reaction initiator.

The obtained value of ΔS41 is as follows.

Key cloth thickness = 40 j m

Surface roughness R z = 38.4 m (JIS-B—06 1 average of 10 points) Haze = 88.8 (JI SK-7105)

Table ®¾ / Measurement translation = 1.230832

Surface light = 11.3 (JIS-Z-8741)

In addition, as shown in FIG. 21, even if the distribution curve has a distribution curve in which “^” is upwardly convex, in this case, the relationship of “average value ^ median of unevenness height is satisfied. The dish of 皿 g41 thus obtained was as shown in Fig. 22. The properties of the cured resin footwear from the ^ !! recess were very good, and the light diffusivity was also ^ ?. Under the same conditions, change only the creation condition of roll ^ si and change the light

I got eight.

I The roll in Example 2 was made by sandblasting the surface with # 200 spherical sand, and the ^ 3S41 value obtained is as follows.

Total decoration thickness = 40 m

Surface roughness Rz = 5.62 m (10 point average roughness of JIS-B-0601) Haze = 78.1 (JIS-K-7105)

Table ^ 1 / Measurement = 1. 019303

Surface light = 11.2 (JIS-Z-8741)

Also, as shown in FIG. 23, the cumulative ¾ ^^ cloth curve, as in Example 1, has a partially upwardly convex distribution curve, and satisfies the relationship of “average value ≥ middle ^ J” of the uneven height. The shape of 41 obtained was as shown in FIG. 24, and the resilience from the concave portion of the cured resin layer was almost good, and the light property was also good.

Example 3)

Under the same conditions as in Example 1, roll ^! The optical sheet 8 was manufactured by changing only the preparation conditions of (1).

The surface of the roll ^ in Example 3 was lightly corroded with a salt solution, After that, sand blasting was performed with sand of # 200 and gloss chrome plating was applied to the surface. The characteristic values of the obtained ¾g 41 are as follows.

Total coating thickness = 40 / zm

Surface roughness Rz = l 6.1 X £ m (10 point average roughness of JIS-B-0601) Haze = 89.5 (JIS-K-7105)

Translation / Measurement = 1.104595

Surface light = 12.5 (JIS-Z-8741)

As shown in FIG. 25, the cumulative frequency distribution curve has an average value of 52% of the maximum value, and the cumulative frequency distribution curve includes a downwardly convex portion and an upwardly convex portion. In this case, there was a little resistance, though sometimes. Therefore, it is determined that the above-mentioned number is a critical condition of about 3 degrees.

The measured value of 5 g 41 was as shown in FIG. 26, and as indicated by the characteristic values, the optical characteristics were good.

Example 4)

Under the same conditions as in Example 1, only the work of the roll ^ was changed to produce a light emitting device 8.

The mouth used at m 4 is a cylindrical surface cut into a ridge with a right-angled isosceles triangular cross-section, and the obtained ^ 41 is a Sil-like cumulative frequency distribution curve as shown in Fig. 27. showed that. This is also a force that corresponds to the critical condition between the curve f A (R) and the curve f B (R) in FIG. 17, the shape of ¾g 41 is as shown in FIG. 28, and the ira property was a child .

(Comparative Example 1)

H. Under the same conditions as in Example 1, only the conditions for forming the roll ^ Si were changed, and the optical fiber sheet 8 was manufactured.

The α-le used in Comparative Example 1 was made of chromium mat (Κ Fushi) This was created by applying a plating layer, and the characteristic values of ^ 41 obtained are as follows.

Total coating thickness = 40 m

Surface roughness Rz = 3.72 m (10 point average roughness of JIS-B-0601) Haze = 82.6 (JIS-K-7105)

Table accessories Z measurement ® «t = l. 012296

Surface light = 15.0 (JIS-Z-8741)

In addition, as shown in FIG. 29, the cumulative 数 S number distribution curve is convex up to ¾ | 5, convex at 13TF, and has an average value and an intermediate value. The cross section was as shown in FIG. 30, and the flexibility was poor.

(H½Example 5)

Optical rat sheet 8 was produced under the same conditions as in Example 1 except that only the preparation conditions were changed.

^ Used in Example 5 was prepared by molding from a polyethylene terephthalate film into which calcium carbonate having a particle size of 1 to 10 m was kneaded, and was prepared by an electrodeposition method. It is as follows.

Key cloth thickness-40

Surface roughness Rz = 2.16 m (10 point average roughness of JIS-B-0601) Haze = 32.5 (JIS-K-7105)

Table ®¾ / Measurement = 1.012211

Surface light 2RS = 55.3 (J I S-Z-8741)

In addition, the cumulative fc ^ distribution curve became a downwardly convex curve over the entire area as shown in FIG. 31, and the cross section of the matrix 41 was as shown in FIG. The optical properties (from the mold) were good.

Table 1 below shows the properties of the light diffusion sheet 8 obtained in Examples 1 to 5 of H½. Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1

Haze value (%)

JIS-K-7105 88.8 78.1 89, 5 32.5 82.6

Gross value (%)

JIS-Z-8741 11.3 11.2 12.5 55.3 15.0

Surface area/

1.230832 1.019303 1.104595 1.012211

/ Measurement area 1.012296

t Surface roughness μ m μτη β m β m μ m U1

IS-B-0601 38.4 5.62 16.1 2.66 3.72

On the back of the light guide plate 殆ど Almost Χ ~ Χ X X X X X X X X

Dot concealability Not visible Visible Visible Visible Visible Visible

Total light transmittance

(%) 84.5 90.5 87.4 87.3 90.6

Projection 4 1 When molding ◎ 〇 △ Slightly heavy 〇〇 X

Mold releasability Very good Good Good Releasable Good Good Good Good No releasability

Example 6)

(Lens sheet 4 fi ^ e

Same as in the case of the optical sheet 8 (the Lorenole for β¾ is different). Using the apparatus shown in FIG.

(1) A take-up roll 11 of a base film made of 100 m-thick and femless biaxially stretched polyethylene terephthalate was prepared.

(2) Prepare a roll ^ l4 engraved with an elliptic cylindrical lenticular lens (same shape and reverse irregularities) 15 on the surface of a metal cylinder, and rotate it around the central axis while curing it with ultraviolet light from the T-die nozzle 21 The conductive resin 16 was supplied to the surface, and the uneven surface of the lens was filled and covered.

③ Next, 前 The material film 12 is unwound from the take-up roll 11 at a speed synchronized with the rotation of the roll 14, and the light is used. Lenticular lens sheet 4 was obtained. The lens sheet 4 was wound up as it was, and then cut into desired dimensions according to ^ before use.

By the way:

Lens;

Unit lens Elliptical cylinder (Long axis is oriented in the direction of the lens sheet.) Long axis length 2b = 230 m

Short axis length 2 a = l 28 # m

Major axis:. 1 / ^/ short axis length = 21) / 23 = 1 80

Repetition cycle per lens p = l 1

Off ^ (length along the major axis of the elliptical cylinder unit lens) D = 50 m Example 7)

Using the light sheet 8 produced in Example 1 and the lens sheet 4 produced in Example 6, an edge light type surface light source having a configuration as shown in FIG. 1 was produced. However, as shown in FIG. 8, the two lens sheets 4 were overlapped so that ^ was perpendicular to each other, and both lenses faced in the exit direction.

The light guide plate 1 and the light source 3 used had the following characteristics.

Light guide plate;

Material; polymethyl methacrylate polymerized fat

Shape; flat it ^ body. Thickness 4 lord

Surface: Finished to a smoothness of center line average roughness of less than Rz = 0.1 m over the entire surface.

On the back side of the light guide plate, print the opaque transparent ink in a circular halftone dot

For δ, a specular reflective film in which aluminum was vacuum-deposited on a polyethylene terephthalate film was placed.

Halftone dots were formed by silk-screen printing using a siri-powered street end dispersed in an acryl-based paste binder.

The dots were arranged vertically and horizontally at a repetition period of 5 mm. The diameter of the halftone dot was 0.2 mm near the light source, increased in proportion to the distance from the light source, and 2.0 mm at the end opposite to the light source.

Light source

As a linear light source, cold-cathode tube-type white fluorescent lamps (power consumption: 4 W, tube diameter: 3 mni) were placed at both ends of the light guide plate. On the opposite side of the light guide plate was placed a metallic anti! ^.

The performance of the surface light source according to the RJL configuration was as follows.

• The angular distribution of luminance is as shown in Figure 33.

• Half angle (0 h) = 72 degrees

• Normal direction brightness (center of light guide plate) = 20 25 c dXm ²

• Distribution of luminance in the weaving direction within the light emission surface; within 5% of soil. Almost uniform visually. (H¾Example 8)

In Example 7, lens sheet 4 was not used, and only optical sheet 8 created in Example 1 was used.

Others were the same as in Example 7 of H.

The performance of the surface light source having the configuration was as follows.

• Fig. 34 shows the angular distribution of luminance.

• Half angle (0h) = 74 degrees (However, even outside the half value angle, there is no sudden attenuation and a certain amount of emitted light is distributed.)

• Luminance in the fiber direction (center of light guide plate) = 1497 cd / m ²

• Distribution of the luminance in the normal direction within the light emission surface; It is almost even visually. • No side lobes.

Medical Example 2)

In Hite Example 7, an ultraviolet-curable acrylate resin paint with a biaxially stretched polyethylene terephthalate film having a thickness of 100; 10 m ^ of the sheet was ffi. The average surface roughness Rz was 3. Oium.

'The angular distribution of luminance is a curve similar to that of FIG. However,

• Half angle (0h) = 76 degrees

• ¾H direction brightness = 1114 cd / m '

• Distribution of luminance in the normal direction within the light emission plane = within ± 5%

Medical case 3)

In Example 7, a surface light source without using the light sheet 8 was created. Incidentally, the ten-point average roughness Rz of the lens sheet Sffi was Rz≤0.1 fim.

The surface light source of £ Lt configuration has a high brightness in the weaving direction on the output surface near the end on the light source side, but the brightness decreases rapidly with the distance from the light source, and the light source near the light fi In the area where (the total length of the rejected Z light guide plate) = 0.2, the brightness was already reduced to such a degree that it was already dark visually.

In the surface light source of the present invention and the display device using the same, the following effects can be obtained.

Since Sheet 8 is formed from a transparent material that does not contain any light diffusing agent particles, it was possible to improve the light source energy utilization rate and achieve high brightness without any light absorption loss due to light diffusion itself.

(^ In the case of the edge light type surface light source of claim 2 of the present invention, since the surface of the light sheet 8 is formed with a ^ group force of the height of the wavelength of the light source light, the edge light type surface light source is guided. When placed on the smooth flat surface of the light plate 1, a gap having the wavelength of the light source light can be reliably formed between the lens sheet 4 and the light sheet 8 and / or between the light sheet 8 and the light guide plate 1. Was.

Therefore, even if the lens sheet 4 is placed, even distribution of the light source light to the entire inside of the light guide plate 1 due to the total reflection of the light on the surface of the light guide plate 1 is not hindered. High brightness can be achieved.

Due to the light spreading effect of the light sheet 8, the halftone dots of the light spreading tfcS layer of the light guide plate 1 became inconspicuous, and it was possible to obtain a high-quality surface light source.

In addition, since the edge light type surface light source of the present invention uses the light sheet 8 and the lens sheet 4, the emitted light can be uniformly distributed within a desired angle gffl, and the emitted light can be distributed. However, it was possible to obtain a uniform luminance distribution over the entire surface without concentrating only near the light source.

Further, when the optical fim sheet 8 of the present invention is placed between the lens sheet 4 and the light guide plate 1 of the edge light type surface light source, the optical contact between the lens sheet 4 and the light guide plate 1 does not occur, and the Newton ring It was possible to prevent the occurrence of interference fringes having the same thickness.

® Optical sheet 8 with random irregularities on the surface and / or In production, the ロール I from the roll 11 was good, and high-quality products could be produced efficiently.

Claims

The scope of the claims

1. A light guide having a surface serving as an exit surface, and a line light provided on at least one side end surface of the light guide is a ^: source, and a light reflection of the light guide ί * ¾® A surface light source consisting of a light sheet placed on the emission surface

The above-mentioned ¾fe diffusion sheet is made of a transparent base material containing no light 光 H ^ particles and has random fine irregularities on the surface, and the minute irregularities have a wavelength of the light source light and a surface roughness of 100 m or less. When the vertical axis represents the percentage of the cumulative frequency distribution of the height of the minute irregularities, and the horizontal axis represents the height of the minute irregularities, a cumulative distribution curve of the height of the minute irregularities is drawn. The surface of the cumulative distribution curve is characterized by a curve that includes a portion that protrudes downward from the coordinate, and that the average value of the heights of the minute irregularities is larger than the median value. light

2. The surface light according to claim 1, wherein the light guide is made of a transparent plate, and the front surface of the light guide is a smooth flat surface having a surface roughness equal to or less than that of the light source light.

3. A lens array sheet or a lens array s array sheet in which unit lenses are arranged in a primary direction or a two-dimensional direction on a plane is laminated on the optical sheet. e surface light

4. The surface light according to claim 1, wherein another light beam having the same physical property value as the above e¾¾¾ sheet is laminated on the light diffusion sheet.

5. One iiLh light source, a lamp house that covers the back of the light source, has a window in front of the light source, and has a light source side internal surface ^ fe ^ A surface light source comprising a light δ £ ¾ sheet,

The diffusion sheet is made of a transparent base material that does not contain light particles, has random fine irregularities on the surface, and the fine irregularities have a surface roughness of 100 μm or less, the wavelength ah of the light source light. And the vertical axis indicates the cumulative percentage of the height of the fine irregularities, When the cumulative distribution of heights of the minute irregularities is drawn using the height as the horizontal axis, the cumulative distribution curve becomes a curve including a downwardly convex portion of the coordinates, and ¾¾¾ A surface light whose special feature is that the average height of the small irregularities is greater than the median value.

6. A lens consisting of unit lenses arranged in a plane on the ± l¾fe 1 sheet in the 1 or 2ΰ) 向 ^ direction.

Claim 6 §S «g surface light o

7. The surface light according to claim 5, wherein another light diffusion sheet having the same physical property values as the light sheet is provided on the sheet.

8. It is made of a transparent base material that does not contain light-expanding particles, and its surface has random fine irregularities whose surface roughness is 100 μππ or less above the wavelength of the light source light. When the distribution curve of the height of the fine irregularities is drawn by plotting the percentage of the S number distribution on the vertical axis and the height of the small irregularities on the horizontal axis, the cumulative curve force An optical sheet characterized by a curve that is concave in a convex portion toward the surface, and wherein the average value of the height of the minute unevenness is larger than an intermediate value thereof.

9. Light 5 ^ ^ It is made of a transparent base material that does not contain particles, the surface has surface roughness force, and the light source has random fine irregularities not less than the wavelength of light and 100 zm or less. When the cumulative curve of height 纖 S 纖 ^ is plotted on the vertical axis, and the height of the minute irregularities is plotted on the horizontal axis, the distribution curve of the height of the small irregularities is plotted. A light diffusion sheet characterized by a curve including a downwardly convex portion, and wherein the average value of the heights of the minute unevenness is larger than an intermediate value thereof;

And the lens sheet

A light diffusion sheet laminate comprising:

Ten.

10. The light diffusion sheet ¾S (* o