JP2001110219A - Planar light source and liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display capable of giving bright planar emission without increasing demand and heating value. SOLUTION: A liquid crystal display comprises a light source 43, a light conductor 42 having the light source arranged on at least one side end face for emitting a beam having peaks right-and-left symmetrical with the normal direction of an emission plane, and a lenticular lens 10 arranged on the emission plane of the light conductor for making the peaks of the beam from the light conductor in the normal direction and the peaks of the beam into a single.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a surface light source using a triangular prism type lenticular lens and a liquid crystal display device using the surface light source as a backlight.

[0002]

2. Related Background Art As a liquid crystal display device, a device using a direct-type or edge-light type diffusion surface light source is known (Japanese Patent Application Laid-Open No. 2-284102, Japanese Patent Application Laid-Open No. 63-318003).
No. JP-A-3-92601). In such a surface light source, a lenticular lens in which a large number of triangular prism type unit lens units are arranged in parallel in order to uniformly and isotropically diffuse emitted light within a desired angle range is used. The conventional lenticular lens has an apex angle α = 60 of the unit lens portion.
° and 90 ° were used. When this lenticular lens is used in combination with a matte transparent diffuser (matte transparent sheet), the light energy of the light source can be simply adjusted to a desired limited angle as compared with that using the matte transparent diffuser. It was possible to obtain a diffuse light having high uniformity and isotropic distribution within the angle range and distributed within the angle range.

[0003]

However, in the above-mentioned prior art, a phenomenon in which a part of light deviates from the above-mentioned angle range (the occurrence of side lobes in the angle distribution of transmitted light intensity).
Was inevitable. Since such a loss of light is not used in a liquid crystal display, a liquid crystal display element, in particular, in the case of a color system, has a drawback of realizing a clear screen while taking advantage of the liquid crystal display with low power consumption. Become. If the output of the light source is increased to solve this problem, the temperature rises due to heat, which is not preferable for the liquid crystal. Further, the light leaking in the side direction is not preferable for a third party as noise (stray light).

An object of the present invention is to solve the above-mentioned problems and to provide a surface light source and a liquid crystal display device capable of obtaining bright surface light emission without increasing power consumption and heat generation in a liquid crystal display. is there.

[0005]

According to a first aspect of the present invention, there is provided a light source, wherein the light source is disposed on at least one side end face, and is symmetrical with respect to a normal direction of a light emitting surface. A light guide that emits a light beam having a peak in a certain direction, and is disposed on the emission surface of the light guide, and makes the peak of the light beam from the light guide a normal direction, and reduces the peak of the light beam. And a lenticular lens to be one.

According to a second aspect of the present invention, there is provided the surface light source according to the first aspect, wherein the lenticular lens has a prism-shaped unit lens portion having a triangular prism on one surface so that the major axes thereof are parallel to each other. The surface light source is characterized in that a large number of the light sources are formed and the other surface is formed so as to have light isotropic diffusion. According to a third aspect of the present invention, in the surface light source according to the first aspect, the lenticular lens has a large number of prism-shaped unit lens portions each having a triangular prism formed on one surface such that major axis directions thereof are parallel to each other. A surface light source characterized in that a light isotropic diffusion layer is formed on the other surface. According to a fourth aspect of the present invention, in the surface light source according to any one of the first to third aspects, an apex angle of the unit lens portion is 95 degrees or more and 110 degrees or less. This is a surface light source. The invention according to claim 5 is the surface light source according to any one of claims 1 to 4, wherein
The pitch of the unit lens portion is 10 to 500 μm,
This is a surface light source characterized in that:

[0007] The invention of claim 6 is the invention of claims 2 to 5
The surface light source according to any one of the above, wherein the prism shape of the unit lens portion is an isosceles triangle in cross section,
This is a surface light source characterized in that: According to a seventh aspect of the present invention, there is provided the surface light source according to any one of the second to fifth aspects, wherein a prism shape of the unit lens portion is a trapezoidal triangle. It is a surface light source. An eighth aspect of the present invention is the surface light source according to the first aspect, further comprising a light reflecting layer formed on a back surface of the light guide.

[0008] The invention of claim 9 is the invention of claims 1 to 8.
The lenticular lens according to any one of the above, wherein the lenticular lens has a prism-shaped unit lens formed of a triangular prism on one surface, and the unit lens is a light emitting surface of the light guide. It is a surface light source characterized by being provided toward the side. According to a tenth aspect of the present invention, there is provided the surface light source according to any one of the first to eighth aspects,
The lenticular lens has a prism-shaped unit lens formed of a triangular prism on one surface, and the unit lens is provided toward a side opposite to a light emitting surface side of the light guide, Surface light source.

An eleventh aspect of the present invention is a liquid crystal display device including a liquid crystal display element and the surface light source according to any one of the first to tenth aspects.

In the lenticular lens of the present invention, by setting the apex angle of the unit lens portion to 95 to 110 °,
The angular distribution of the intensity of the diffused light emitted from the diffused light emission surface is substantially uniform and isotropic only within a desired angle range, and no side lobes are generated, which is suitable for an edge light type surface light source or the like. Can be used.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings and the like with reference to the drawings. (Embodiment of Integrated Lenticular Lens) FIG.
1 is a perspective view illustrating a first embodiment of a lenticular lens according to the present invention. In the lenticular lens 10 according to the first embodiment, a large number of prism-shaped unit lens portions 12 each having a triangular prism are formed on one surface of a light-transmitting substrate 11 so that long axes (ridges) are parallel to each other. The other surface of the optical substrate 11 is a flat surface 13. The unit lens portion 12 has a vertical angle of 95 ° when the apex angle of the main cut surface is α.
≦ α ≦ 110 °.

The translucent substrate 11 is made of a homo- or copolymer of acrylate or methacrylate such as polymethyl methacrylate or polymethyl acrylate, polyester such as polyethylene terephthalate or polybutylene terephthalate, polycarbonate, It is a sheet-shaped or plate-shaped member made of a transparent material such as a transparent resin such as polystyrene, a transparent glass, or a transparent ceramic such as a transparent ceramic. This translucent substrate 11
Has a thickness of 20 to 1 when used for a back light source.
It is preferable to use one having a planar shape of about 000 μm. The pitch of the unit lens portion 12 is preferably approximately 10 to 500 μm, though it depends on the application. As a method of forming the prism shape, for example, a known hot pressing method (described in JP-A-56-157310), an ultraviolet curable thermoplastic resin film is embossed with a roll embossing plate, and then irradiated with ultraviolet rays. And a method of curing the film (described in JP-A-61-156273).

The translucency required for the translucent substrate 11 must be selected so as to transmit diffused light at a minimum so as not to hinder the use of each application. It may be colored transparent or matte transparent. Here, the term “matte transparency” refers to the property of transmitting transmitted light almost uniformly and isotropically in all directions within a semi-solid angle, and is used synonymously with light isotropic diffusion. That is, matte transparency means that the transparent substrate 11
The angle distribution I ⁰ (θ) of the transmitted light intensity when a parallel light beam is incident from the back surface (incident angle i = 0) is represented by cos distribution [I ⁰ (θ) =
I ⁰ _mp cos θ, −90 ° ≦ θ ≦ 90 °, θ indicates an angle formed with the normal line N, and I ⁰ _mp indicates transmitted light intensity in the normal direction) or a distribution similar thereto. The definition of I ⁱ (θ) will be described later.

FIG. 2 shows a second embodiment of a lenticular lens according to the present invention.
It is a perspective view which shows embodiment. The lenticular lens 10 according to the first embodiment is formed as a single body of the light-transmitting base material 11, whereas the lenticular lens 10 ′ according to the second embodiment is formed on a flat light-transmitting substrate 14. This is a structure in which a lens layer 15 made of a light-transmitting material and having a prism-shaped unit lens portion 12 made of a triangular prism is laminated. Also in this embodiment, the unit lens section 12 is set so that 95 ° ≦ α ≦ 110 °, where α is the apex angle.

(Measurement of Transmission) The present inventors performed various measurements of transmission on the lenticular lens 10, and the results are shown in FIGS. Here, the measurement conditions are shown and will be cited in the following discussion. Transmission measurement: FIG. 11 Lenticular lens with apex angle α = 90 ° (the lens portion is on the light source side) Incident angle i = 0 ° Transmission measurement: FIG. 12 Matte transparent sheet (light isotropic diffusion layer) Incident angle i = 0 ° Transmission measurement: FIG. 13 Lenticular lens with apex angle α = 90 ° + matte transparent sheet, incident angle i = 0 ° Transmission measurement: FIG. 14 Lenticular lens with apex angle α = 100 ° + matte transparent sheet, incident angle i = 0 ° Transmission measurement: FIG. 15 Lenticular lens with apex angle α = 110 ° + matte transparent sheet Incident angle i = 0 ° Transmission measurement: FIG. 16 Layer structure of claim 1 and apex angle α = 90 ° (isosceles triangle) 3. A lenticular lens having a prism period of 100 μm + a matte transparent sheet (solid line), and a lenticular lens having a layer configuration of claim 2 and an apex angle α = 90 ° (an isosceles triangle) and a prism period of 50 μm + a matte transparent sheet ( (Dashed line) Lenticular lens of α = 100 ° + matte transparent sheet (dotted line) Matte transparent sheet (dotted line) Incident angle i = 63 ° Transmission measurement: FIG. 17 Layer configuration of claim 1 and apex angle α = 3. A lenticular lens with 90 ° (isosceles triangle) and a prism period = 100 μm + a matte transparent sheet (solid line). A lenticular lens having the layer structure of claim 2 and an apex angle α = 90 ° (isosceles triangle) and a prism period = 50 μm. Lens + matte transparent sheet (dashed line) Lenticular lens with apex angle α = 100 ° + matte transparent sheet (dashed line) matte transparent sheet (dotted line) Incident angle i = 30 °

(Explanation of apex angle α) The unit lens portion 12 of the triangular prism type has a shape to obtain a transmitted light intensity I (θ) symmetrical with respect to the normal line N of the bottom surface or the base material surface. Is
Either an isosceles triangle (symmetrical with respect to the normal N) (see FIG. 3) or a transmitted light distribution I (θ) on either side
When many are biased, a scalene triangle is formed (see FIG. 4). However, the apex angle α is 95 ° ≦ α in any case.
≦ 110 °, and particularly preferably around α = 100 °.

The reason why the lower limit of the apex angle α is 95 ° is as follows. If α ≧ 95 °, transmission of a laminate of a triangular prism type lenticular lens and a matte transparent translucent substrate (or one in which the lenticular lens itself is a matte transparent substrate) Light intensity I
^This is because the distribution of ⁱ (θ) has negligible influence due to side lobes (side lobes) generated in the peripheral portion away from the main direction. Specifically, if the side lobe to main lobe ratio of the light intensity is R, it has been found that R ≦ 15% (FIGS. 13 to 17). That is, in the case of observing a character image or the like using a liquid crystal display device or the like, one of the optical characteristics required for the back light source is 30 to 100 ° left and right around the normal direction (particularly, 30 to 100 °).
It is necessary to secure bright and uniform isotropic diffused light only within the angle range of 60 °). This is because television screens, clocks, lighting advertisements, various monitors, and the like are usually observed exclusively within the above-mentioned angle range, and it is usually impossible to observe outside this angle range. .
However, within this angle range, the screen must be visible from any angle with the same illuminance and sharpness. This can be easily understood by assuming that the screen is observed in a state where a plurality of persons are arranged side by side in front of the television screen. Light traveling out of this angle range results in light loss and gives unwanted noise light in unrelated directions and should be suppressed rather. For this purpose, the distribution of the transmitted light intensity I ⁱ (θ) is 30 ° to the left and right including the normal direction.
It is necessary to include most of the transmitted light amount within 100 °.

To evaluate this, the following two parameters are effective. Diffusion angle The diffusion angle is, for example, as shown in FIG. 5, the transmitted light intensity I ⁱ (θ) is the peak direction of the main lobe (the direction in which the transmitted light intensity of the main lobe is the strongest, not necessarily the normal direction). However, the evaluation is preferably performed at an angle θ _{10 %} within a range having an intensity of 10% or more of the transmitted light intensity _Imp of the transmitted light. Side rope to main lobe ratio Diffusion angle θ _10% is optimal range (30 ° ≦ θ _10% ≦ 100 °)
However, if the light intensity due to the side lobes is large, the above-described loss of light and leakage of noise light to a third party cannot be prevented. The side lobe to main lobe ratio R evaluates the influence of the side lobe, and is given by the following equation. R = (I _sp / I _mp ) × 100 [%] (1) where I _sp : peak direction intensity of side lobe I _mp : peak direction intensity of main lobe From the viewpoint of preventing the influence of optical noise on (the side direction of the liquid crystal display element), R ≦ 20.
It has been found that these effects of side lobes are virtually negligible at%.

In addition, according to the results of experiments conducted by the present inventors,
The value of R is the apex angle α of the unit lens unit 12 of the triangular prism type.
It was found that in the range of α <95 °, R was in the range of 20%, and suddenly decreased around α = 95 °. For example, as shown in FIG. 7A, a triangular prism type lenticular lens 10 laminated with a light isotropic diffusion layer (matte transparent sheet) 20 is vertically incident from the back surface (incident angle i = 0). 13), when the light ray is incident at R = 26% (> 20%) when the apex angle α of the unit lens portion 12 is 90 °, as shown in FIG. In addition, it can be seen that when α = 100 °, R is drastically reduced to 13%. Further, as shown in FIG.
At 110 °, R = 6%.

The reason why the upper limit of the apex angle α is 110 degrees is as follows. If α> 110 °, then the diffusion angle θ
_{Since 10%} deviates from the angle range, α ≦ 11
Must be 0 °. For example, when α = 90 °, θ _10% = 82 ° (see FIG. 13), when α = 100 °, θ _10% = 90 ° (see FIG. 14), and gradually increases.
When α = 110 °, θ _10% = 98 ° (see FIG. 15), and it can be seen that the required upper limit of the diffusion angle is reached. Further, when α = 180 ° as a limit where α is increased, that is, considering a perfect plane, when the matte transparent sheet 20 is a single body, there is no other choice but in that case, as shown in FIG. It can be seen that the angle θ _10% reaches 140 °.

(Definition of transmitted light intensity I ⁱ (θ)) The angle dependence of the intensity of light transmitted through a light-diffusing and transmissive substance depends on the direction of a transmitted light beam and the direction of an incident light beam. What shows a value for evaluating the angle dependence of the transmitted light intensity is I
ⁱ (θ). That is, as shown in FIG. 6, the transmitted light intensity I ⁱ (θ) is, among the light that diffuses and transmits in various directions and emits light when a light ray with an incident angle i is incident, It is defined as the light intensity traveling in the direction of angle θ with respect to the normal direction of the emission surface.

(Light Isotropic Diffusive Layer) Light Isotropic Diffusive Layer 20
As the light-transmissive material, an inorganic fine particle such as calcium carbonate, silica, alumina, barium carbonate or the like, or a resin bead particle such as an acrylic resin dispersed as a light diffusing agent (matting agent) is used, The diameter of the particles is approximately 1 to 20
Those having a size of about μm are used. As the light isotropically diffusing layer 20, a single layer formed by extruding or calendering a resin material obtained by kneading the light diffusing agent into the translucent material can be used. Further, the light-transmitting material is coated on a sheet (or plate) of the light-transmitting material with a binder.
Alternatively, a two-layer structure may be used in which a coating material in which the light diffusing agent is dispersed is applied and formed. Further, the surface of the sheet (or plate) of the translucent material is subjected to sand blasting, embossing and shaping, or the like to have a center line average roughness of 1 to 20 μm.
m may be formed with fine irregularities (grain and the like).

FIGS. 7 to 10 are diagrams showing the layer structure of the lenticular lens and the light isotropic diffusion layer. When the lenticular lens 10 and the light isotropically diffusing layer 20 are stacked and used, the lenticular lens 10 is on the observation side and the light isotropically diffusing layer 20 is on the light source side (FIGS. 7 and 9). There is a case on the opposite side (FIGS. 8 and 10). At this time, the unit lens unit 12 of the lenticular lens 10 may be on the observation side [FIGS. 7A to 10A], or the unit lens unit 12 may be on the light source side. 7 (B) to FIG. 10 (B)]. The light isotropically diffusing layer 20 may be a sheet (or a plate) (FIGS. 7 and 8) or may be directly applied to the lenticular lens 10 like the light isotropically diffusing layer 20 ′. It may be in the form of a film (FIGS. 9 and 10).

(Embodiment of Direct Type Surface Light Source) FIG.
FIG. 19 is a sectional view showing a first embodiment (direct type) of a surface light source according to the present invention, and FIG. 19 is a diagram illustrating transmitted light intensity in the embodiment of FIG. The direct-type surface light source 30 is the case 3
1, a linear light source 32 such as a fluorescent lamp is provided, and a lenticular lens 10 and an isotropic light diffusing layer 20 are provided on the opening side of a case 31. Light isotropic diffusion layer 2
The transmitted light intensity I ₁ ⁱ (θ) of 0 is a cos distribution,
The result is as shown in FIG. On the other hand, the lenticular lens 10 functions to refract light incident from the linear light source 32 and split the light into two directions, and the transmitted light intensity I ₂ ⁱ thereof.
(Θ) is as shown in FIG. Accordingly, the transmitted light intensity I ₃ ⁱ (θ) of the surface light source 30 is obtained by superposing the two, and I ₃ ⁱ (θ) = I ₁ ⁱ (θ) × I ₃
ⁱ (θ), which is a shape as shown in FIG.

(Embodiment of Edge Light Type Surface Light Source) FIG. 20 is a sectional view showing a second embodiment (edge light type) of a surface light source according to the present invention, and FIG. 21 illustrates characteristics of a light guide plate. FIG. 22 is a diagram for explaining the transmitted light intensity of the embodiment of FIG. Edge light type surface light source 4
In No. 0, the reflection layer 42 is formed on the lower surface of the light guide plate 41, and the lenticular lens 10 and the light isotropic diffusion layer 20 are disposed on the upper surface of the light guide plate 41. The light source 43 and the reflection film 4 are provided on both sides of the side end surface of the light guide plate 41, respectively.
4, an illumination cover 45 is provided.

When the incident angle i of the light guide plate 41 is larger than the critical angle ic, as shown in FIG.
Only propagates while totally reflecting inside the light guide plate 41,
There is no transmitted light from the emission surface 41a. On the other hand, when the incident angle i is smaller than the critical angle ic, as shown in FIG. 21B, a part of the light rays And the rest is transmitted and emitted. In the actual light guide plate 41, FIG.
As shown in FIG. 1 (C), by placing a light source 43 'on the other end face or providing a light reflecting layer 42', a light beam propagates in the light guide plate 41 in both directions or a standing wave. As shown in FIG. 21 (D), from the emission surface 41a, ± θ symmetrical with respect to the normal
Light is emitted in the direction. This angle is θ = 60 ° and θ
= It is known to have a sharp peak in the direction of -60 °. Therefore, in order to deflect the light in the vicinity of the normal direction where the observer is present, the light beam is refracted by using the lenticular lens 10 and, as shown in FIG. Θ = 30 °, −30 °). Therefore, in the case of either the direct-type or the edge-light type surface light source, light emitted from the emission surface has an angular distribution having peaks in two directions symmetric with respect to the normal to the emission surface (FIG. 11). ). However, this still cannot be said to be a uniform surface light source, and the normal direction where the observer is present becomes dark. Therefore, by further combining the light isotropic diffusion layer (matte transparent layer) 20, It has a gentle peak in the normal direction and usually
It is possible to obtain a surface light source that emits diffused light only within a range of 30 to 100 ° required for the observer.

The surface light source 40 is different from the direct surface light source 30 in that the light transmitted from the light guide plate 41 is not in the normal direction but in two directions symmetric with respect to the normal, for example, ± 63. °
For both the light isotropic diffusion layer 20 and the lenticular lens 10, the transmitted light intensity I ⁱ (θ) is such that the axis of symmetry is rotated by ± 63 ° in the normal direction with respect to the transmitted light in these two directions. [FIG. 22 (A), (B)], which are further combined (product of I ⁱ (θ)) to obtain the surface light source 4
The transmitted light intensity I ⁱ (θ) is 0 [FIG.
(B)]. FIGS. 16 and 17 show that θ = + 6
Only the transmitted light intensity I ⁱ (θ) in the directions of 3 ° and −30 ° is illustrated. At this time, peaks A and B in FIG. 22B cause side lobes A ′ and B ′. By setting the vertex angle α of the unit lens unit 12 to α ≧ 95 °,
The side lobes A 'and B' can be significantly attenuated.

(Embodiment of Light Reflecting Layer) FIG. 23 is a view showing an embodiment of a light reflecting layer used for an edge light type surface light source. The light reflection layer 42 is a layer having a performance of diffusing and reflecting light, and can be configured as follows. As shown in FIG. 23A, a white layer 42A in which a pigment having high concealment and high whiteness, for example, a powder of titanium dioxide, aluminum or the like is dispersed is formed on one surface of the light guide plate 41 by painting or the like. As shown in FIG. 23B, matte fine irregularities 41a are formed on one surface of the light guide plate 41 by sand brightening, embossing, or the like, and a metal such as aluminum, chromium, silver, or the like is plated or vapor-deposited. The metal thin film layer 42
Form B. As shown in FIG. 23C, a metal thin film layer 42B is formed on a white layer 42A ′ similar to FIG. 22A (however, the concealing property may be low). As shown in FIGS. 23 (D1) and (D2), they are formed on a halftone dot-shaped white layer 42A ", and the area ratio is increased as the distance from the light source 43 increases, so that the attenuation of the light amount of the light source 43 is corrected. Is also good.

The surface light sources 30, 40 shown in FIGS.
Can be used as a liquid crystal display device by disposing it on the back of a known transmission type liquid crystal display element.

[0030]

As described above in detail, according to the present invention, the intensity of the side lobe causing light loss and stray light (optical noise) can be greatly attenuated, and a limited angle can be obtained. Within the range (30 ° left and right around the normal direction)
(100 °). Therefore, when used as a surface light source, bright surface light emission can be obtained without increasing power consumption or heat generation. At this time, the light diffusion angle and the uniform isotropy of the light intensity within the diffusion angle can be maintained at substantially the same level as in the related art.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of a lenticular lens according to the present invention.

FIG. 2 is a perspective view showing a second embodiment of the lenticular lens according to the present invention.

FIG. 3 is a diagram for explaining a vertex angle of a unit lens unit of the lenticular lens according to the present embodiment.

FIG. 4 is a diagram for explaining a vertex angle of a unit lens unit of the lenticular lens according to the present embodiment.

FIG. 5 is a diagram for explaining a diffusion angle.

FIG. 6 is a diagram for explaining transmitted light intensity I ⁱ (θ).

FIG. 7 is a diagram showing a combination of a lenticular lens and a light isotropic diffusion layer.

FIG. 8 is a diagram showing a combination of a lenticular lens and a light isotropic diffusion layer.

FIG. 9 is a diagram showing a combination of a lenticular lens and a light isotropic diffusion layer.

FIG. 10 is a diagram showing a combination of a lenticular lens and a light isotropic diffusion layer.

FIG. 11 is a diagram showing a result of a transmission measurement (a lenticular lens having a vertex angle of 90 degrees).

FIG. 12 is a diagram showing the results of transmission measurement (light isotropic diffusion layer).

FIG. 13 is a diagram showing a result of transmission measurement (a combination of a lenticular lens having a vertex angle of 90 degrees and a light isotropic diffusion layer).

FIG. 14 is a diagram showing transmission measurement results (combination of a lenticular lens having a vertex angle of 100 degrees and a light isotropic diffusion layer).

FIG. 15 is a diagram showing the results of transmission measurement (combination of a lenticular lens having a vertex angle of 110 degrees and a light isotropic diffusion layer).

FIG. 16 is a diagram showing the result of transmission measurement (incident angle of 63 degrees).

FIG. 17 is a diagram showing the result of transmission measurement (incident angle of 30 degrees).

FIG. 18 is a sectional view showing a first embodiment (direct type) of a surface light source according to the present invention.

FIG. 19 is a diagram illustrating transmitted light intensity in the embodiment of FIG. 18;

FIG. 20 shows a second embodiment of the surface light source (edge light type).
It is sectional drawing which showed.

FIG. 21 is a diagram illustrating characteristics of a light guide plate.

FIG. 22 is a diagram illustrating transmitted light intensity in the embodiment of FIG. 20;

FIG. 23 is a diagram showing an embodiment of a light reflection layer used for an edge light type surface light source.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Lenticular lens 11 Translucent base material 12 Unit lens part 20 Light isotropic diffusion layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) G02F 1/13357 G09F 9/00 336E G09F 9/00 336 F21Y 103: 00 // F21Y 103: 00 G02F 1 / 1335 530 (72) Inventor Hiroyuki Amemiya 1-1-1, Ichigaya-Kagacho, Shinjuku-ku, Tokyo Inside Dai Nippon Printing Co., Ltd. (72) Inventor Nobumasa 1-1-1, Ichigaga-cho, Ichigaya-cho, Shinjuku-ku, Tokyo Dainippon Printing Co., Ltd.

Claims (11)

[Claims] 1. A light source, a light guide, wherein the light source is disposed on at least one side end surface, and a light guide that emits a light beam having a peak in a direction symmetrical with respect to a normal direction of an emission surface. A lenticular lens disposed on an emission surface of a body, wherein a lenticular lens that normalizes the peak of the light beam from the light guide and reduces the peak of the light beam to one. 2. The surface light source according to claim 1, wherein the lenticular lens is formed with a large number of prism-shaped unit lens portions each having a triangular prism on one surface so that major axis directions thereof are parallel to each other. A surface light source characterized in that the other surface is formed to have light isotropic diffusion. 3. The surface light source according to claim 1, wherein the lenticular lens is formed by forming a large number of prism-shaped unit lens portions each having a triangular prism on one surface so that major axis directions thereof are parallel to each other. A surface light source characterized in that a light isotropic diffusion layer is formed on the other surface. 4. One of claims 1 to 3
3. The surface light source according to claim 1, wherein a vertex angle of the unit lens portion is 95 degrees or more and 110 degrees or less. 5. The method according to claim 1, wherein:
The surface light source according to claim 1, wherein a pitch of the unit lens unit is 10 to 500 μm. 6. Any one of claims 2 to 5
3. The surface light source according to claim 1, wherein the prism shape of the unit lens portion is an isosceles triangle in cross section. 7. One of claims 2 to 5
3. The surface light source according to claim 1, wherein the prism shape of the unit lens unit is a trapezoidal triangle. 8. The surface light source according to claim 1, further comprising a light reflection layer formed on a back surface of the light guide. 9. Any one of claims 1 to 8
The lenticular lens according to claim 1, wherein the lenticular lens has a prism-shaped unit lens formed of a triangular prism on one surface, and the unit lens is provided toward a light emitting surface side of the light guide. A surface light source characterized in that: 10. The surface light source according to claim 1, wherein the lenticular lens has a prism-shaped unit lens having a triangular prism on one surface, The surface light source, characterized in that the unit lens is provided facing a side opposite to a light emitting surface side of the light guide. 11. A liquid crystal display device comprising: a liquid crystal display element; and the surface light source according to any one of claims 1 to 10.