KR19980069863A - Light guide, manufacturing method of light guide, and surface light source - Google Patents

Abstract

A planar light source for a backlight in which the number of uses of the lenticular lens sheet is reduced or made even more unnecessary, and a manufacturing cost of the light guide is reduced.

The light guiding body 1 is provided with a transmissive lens unit 2 composed of a plurality of lenticular unit lenses molded with the same resin as the light guiding body 1. [ The lenticular unit lens of the transmission lens unit 2 is a triangular prism of a concave or convex shape, and these ridgeline directions are arranged approximately parallel to each other. Further, the vertex angle of the prism of the triangular prism is formed at 125 to 165 degrees. And a light opaque treatment is performed so that light is not transmitted through the surface opposed to the transmissive lens portion 2.

Description

Light guide, manufacturing method of light guide, and surface light source

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light guide, a method of manufacturing the light guide, and a planar light source, and more particularly to a planar light source used for a backlight for a liquid crystal display or the like, And a method of manufacturing the light guide.

As a planar light source for backlight of a liquid crystal display (LCD), an edge light type is known which uses a translucent flat plate as a light guide. As such a surface light source, light is made incident from both sides or one side of a side surface of a light guide made of a transparent parallel plate, and light is widely propagated throughout the light guide by utilizing total internal reflection inside the light transmitting plate, Scattered reflection light of less than the critical angle in the light scattering reflector on the back surface of the light guide, and diffused light is emitted from the surface of the light guide (Acts 55-162201).

A lens sheet having a projection of a triangular prismatic lenticular lens on one side and a smooth surface on the other side is superimposed on the surface of the light guide of the above surface light source with the projection surface facing upward, It is also known that the diffused radiation can be uniformly diffused in an isotropic manner within a desired angle range (see Japanese Unexamined Patent Publication No. 4-107201).

When this lens sheet is used in combination with a chlorine transparent diffuser plate (chlorine transparent sheet), the light energy of the light source is focused mainly within a desired limited angular range, rather than using only a chlorine transparent diffuser plate (US Patent No. 4729067) And diffused light having high uniform isotropy can be obtained within the angular range.

In recent years, as a countermeasure for high brightness of a backlight used in a liquid crystal display device, there is a tendency to employ a configuration in which two lenticular lens sheets are superimposed at right angles as shown in Fig. 1 (Monthly Display, May 1995, pp. 35 to P39 ).

However, the backlight of the conventional liquid crystal display device has a problem that the visual characteristics are comparatively narrow. In addition, since two lenticular lens sheets are used, the cost of parts is increased accordingly, and two lenticular lens sheets There is a problem in that a lot of manufacturing costs are incurred and the backlight itself becomes very expensive.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a planar light source for a backlight which reduces component cost and manufacturing cost by making the number of lenticular lens sheets used one sheet or more unnecessary, And a method of manufacturing the light guide.

In order to achieve the above object, the light guide of the present invention according to claim 1 of the present invention is a light guide which emits light emitted from a light source provided adjacent to at least one side end face from a light emission surface, And a plurality of concave or convex lenticular unit lenses molded from the same resin as the light guide, wherein the plurality of lenticular unit lenses of the first lens unit have a triangular prism The prism portion is characterized in that these ridge directions are arranged substantially parallel to each other.

According to a second aspect of the present invention, in the light guide according to the first aspect, the angle of the apex of the plurality of lenticular unit lenses of the first lens unit is 135 ° to 165 °.

In the light guide according to the third aspect of the present invention, in the light guide according to the first or second aspect, the angle of the apex of the plurality of lenticular unit lenses of the first lens unit is about 150 degrees .

The light guide according to claim 4 of the present invention is the light guide according to any one of claims 1 to 3, wherein a plurality of light-reflecting surfaces opposite to the light- And a plurality of lenticular unit lenses of the second lens unit are prism portions of a triangular prism having an apex angle of 125 to 165 degrees, And are arranged substantially parallel to each other.

According to a fifth aspect of the present invention, in the light guide according to the fourth aspect, the angles of the plurality of lenticular unit lens apices of the second lens unit are 135 ° to 165 °.

In the light guide according to the sixth aspect of the present invention, in the light guide according to the fourth or fifth aspect, the angle of the apexes of the plurality of lenticular unit lenses of the second lens unit is about 150 degrees.

The light guide according to claim 7 of the present invention is the light guide according to any one of claims 4 to 6, wherein a ridge line direction of a plurality of lenticular unit lenses of the first lens unit, a plurality of Of the lenticular unit lenses are arranged so that the ridgeline directions of the lenticular unit lenses of the second lens unit are substantially straight.

The planar light source of the present invention according to claim 8 is characterized by comprising a light guide according to any one of claims 1 to 7 and a light source provided adjacent to at least one side end face of the light guide.

The method for manufacturing a light guide of the present invention according to claim 9 is characterized in that the method for manufacturing a light guide according to any one of claims 1 to 7 includes the step of molding the light guide to a metal mold do.

1 is a schematic view showing a conventional liquid crystal display device.

2 is a perspective view showing a light guide according to the present invention.

3 is a graph showing luminance distribution characteristics.

4 is a graph showing viewing angle characteristics.

5 is a perspective view showing a light guide according to the present invention.

6 is a schematic view showing a liquid crystal display device having a planar light source according to the present invention.

7 is a perspective view showing a light guide.

8 is a schematic view showing a cross-sectional shape of a prism portion of a triangular column.

9 is a graph showing a change in the luminance distribution characteristic with respect to the prism pitch.

DESCRIPTION OF THE REFERENCE NUMERALS

1:

1a: side cross section

1b: Lenticular lens unit

2:

3:

4: Light source

5: Surface light source

6: liquid crystal panel

BRIEF DESCRIPTION OF THE DRAWINGS Fig.

7A and 7B are perspective views showing the light guide, and the following terms are defined using this drawing.

The lenticular unit lens means a prism of a triangular prism having a triangle formed by a vertex ABC in a bottom plane in Fig. 7A, and a prism in a pentagonal prism having a pentagon formed in a vertex ABDEC in Fig. 7B as a bottom plane. However, the lenticular unit lens 1b exemplified here is merely an example, and is not limited thereto. Although the lenticular unit lens in this drawing shows only the convex shape, it may be concave although not shown.

The prism portion of the triangular prism of the lenticular unit lens is a prism of a triangular prism having a triangle formed by a vertex ABC as a bottom surface in both Figs. 7A and 7B.

The top of the prism portion of the triangular pillar, Figs. 7A and 7B both refer to apex A.

The angle of the apex of the prism portion of the triangular pillar refers to the angle formed by the point BAC in both Figs. 7A and 7B.

8A, 8B and 8C are schematic views showing the cross-sectional shape of a prism portion of a triangular column.

The prism portion of the triangular prism is preferably an isosceles triangular shape as shown in Fig. 8A. However, for example, as shown in Fig. 8B, the top portion A is slightly lacking to form a pentagon, Even if a curved shape is formed, the prisms of these shapes are all included in the prism portion of the triangular prism of the present invention since they have little effect on the performance of the light guide.

2 is a perspective view showing a light guide according to the present invention.

The light guiding body 1 is formed with a transmissive lens unit 2 composed of a plurality of lenticular unit lenses molded with the same resin as the light guide 1. In addition, a light reflection treatment (for example, an acid point scattering process such as fine irregularity and screen printing) for uniformly diffusing light by diffusing light is performed on the opposite surface of the transmission lens unit 2, In order to prevent light leakage, a reflection plate is provided in a subsequent process (not shown).

The lenticular unit lens of the transmission lens unit 2 is a prism of a triangular prism. The ridgeline directions thereof are arranged substantially parallel to each other. Particularly, the apex angle of the prism of the triangular prism is set to be 125 to 165 degrees Lt; / RTI > In addition, if the vertex angle of the prism of the triangular prism is in the range of 125 to 165 degrees, vibrations or fluctuations of the prism size, pitch, height, and apex angle of the triangular prism do not affect the performance of the light guide. In particular, as shown in Fig. 9, it can be seen that even if the pitch of the prism is changed in the range of 10 mu m to 1000 mu m, the luminance distribution characteristic does not largely change.

As the material of the light guide 1, a light-transmitting material is selected. Typically, resins of acrylic or polycarbonate are used. The thickness of the light guide is usually about 1 to 10 mm.

Examples of other light-transmissive materials include acrylic acid esters such as methyl methacrylate and methyl polyacrylate, methacrylic acid esters alone or copolymers, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polycarbonates, polystyrene , Polymethylpentine, or transparent ceramics such as a transparent resin such as an acrylate or an unsaturated polyester such as polyester acrylate and a polyfunctional urethane acrylate crosslinked with ultraviolet rays or electron rays, or a transparent glass.

Next, the operation of the light guide according to the present invention will be described with reference to FIG.

The light emitted from a light source (not shown) provided adjacent to the side end face 1a of the light guide body 1 enters the inside of the light guide body 1 from the side end face 1a, The light reflected by the opposite face of the lens portion 2 and the side end face other than the side face 1a and directed in the direction of the transmission lens portion 2 has the function of focusing the light, The light is emitted from the transmission lens unit 2 which diffuses uniformly in an isotropic manner into the light guide plate 2 (upward in Fig. 2).

3 is a graph showing luminance distribution characteristics.

The horizontal axis indicates the length of the light guide, the position of the light guide from the lamp is expressed as a percentage, the position of the value 0 is the position of the end face of the light guide closest to the lamp, It is the position of the end face of the light guide which is farthest from the lamp.

The vertical axis does not denote a unit, but a larger value as the luminance means bright.

3 is an analysis of the luminance distribution characteristic of the light guide body using CODEV, which is an optical design evaluation software developed by ORA Corporation of the United States. The wavelength of the light irradiated from the lamp is 600 nm, Refractive indices of a typical PMMA of 1.49 are used as the material of the light guide, and the prism angles of the triangular prisms are 90 °, 120 °, 125 °, 150 °, 165 ° and flat (ie, And shows the simulation result of the luminance distribution characteristic in the case of changing the luminance distribution characteristic.

As evident from the figure, the luminance distribution characteristic of 90 deg. To 120 deg., Which is the apex angle of the lens sheet used with the conventional light guide, is not only inferior to that of flat, but also from 125 deg. To 165 deg. Is remarkably improved as compared with the conventional luminance distribution characteristics from 90 DEG to 120 DEG. Further, the characteristic improvement from 135 DEG to 165 DEG is remarkable, and it can be easily understood that a peak effect appears in the luminance distribution characteristic in the vicinity of 150 DEG.

However, even if the wavelength of the light or the refractive index of the light guide material is slightly changed, there is no great influence on the brightness distribution characteristics found here. In addition, the applicant of the present application has deviated from the stereotypes of 90 ° to 120 °, which is the range of the apex angle of the conventional lens sheet, and independently performed the basic optical design simulation of the light guide. As a result, And a completely new light guide plate is proposed based on the result.

4 is a graph showing viewing angle characteristics.

A horizontal axis indicates a viewing angle with respect to the light guide, and a value 0 (not shown) means a direction perpendicular to the light guide, and a value -90 means a horizontal direction with respect to the light guide.

Although the unit of the vertical axis is not shown, the larger the value is, the brighter the brightness.

The graph of FIG. 4 is obtained by analyzing the viewing angle characteristics of the light guide by using CODEV as described above. As the evaluation parameter, the wavelength of the light emitted from the lamp is 600 nm, the refractive index of a typical PMMA Simulation of luminance distribution characteristics when prismatic angles of triangular prisms are changed to 90 °, 120 °, 125 °, 135 °, 150 °, 165 ° and flat (ie without triangular prism prism) using 1.49 Fig.

As can be clearly seen from the figure, when comparing the viewing angle characteristics of 90 ° and the viewing angle of 120 °, which are apex angles of the lens sheet used together with the conventional light guide, the result is much worse than 120 ° On the other hand, the viewing angle characteristics from 125 DEG to 165 DEG are much improved as compared with the conventional viewing angle characteristics of 90 DEG, and it is easy to understand that the peak effect is exhibited.

5 is a perspective view showing a light guide according to the present invention.

The light guiding body 1 is provided with a transmissive lens portion 2 and a reflective lens portion 3 which are formed of a plurality of lenticular unit lenses molded with the same resin as the light guide 1.

Each of the lenticular lens units of the transmission lens unit 2 and the reflection lens unit 3 is a prism of a triangular prism, the ridgeline directions thereof are arranged substantially parallel to each other, and the plurality of lenticular unit lenses of the transmission lens unit 2 The ridgeline direction and the ridgeline direction of the plurality of lenticular unit lenses of the reflective lens unit 3 are arranged to be substantially straight.

A reflection surface treatment by aluminum deposition or the like is performed on the lower surface of the reflection lens unit 3 (not shown) so that light is not transmitted.

Next, the operation of the light guide according to the present invention will be described with reference to Fig.

The light emitted from a light source (not shown) provided adjacent to the side end face 1a of the light guide body 1 (the right lateral direction in Fig. 5) enters the inside of the light guide body 1 from the side end face 1a, And is reflected on the lower surface of the reflecting lens portion 3 or the side end surface other than the side surface 1a. At this time, the reflective lens unit 3 has the function of making the light guided to the transmissive lens unit 2 in the light guide 1 uniform, and guides the diffused light toward the transmissive lens unit 2 .

The light guided by the reflective lens unit 3 in the direction of the transmissive lens unit 2 has a function of focusing the light and transmits the diffused radiation in a uniformly isotropic manner within a desired angle range. 2 (upper direction in Fig. 5).

6 is a schematic view showing a liquid crystal display device having a surface light source according to the present invention.

The liquid crystal display device is constituted by a liquid crystal panel 6 and a planar light source 5 and the planar light source 5 is constituted by a light guide 1 according to the present invention and a light source 4 such as a fluorescent tube and various control circuits ) And the like.

The light emitted from the light source 4 enters the inside of the light guide 1 from the side end face and is reflected by the side end face other than the bottom face or the side end face of the reflecting lens portion 3, And is uniformly isotropically diffused into the angle range and guided to the liquid crystal panel 6.

Further, in the method of manufacturing a light guide according to the present invention, by using a mold obtained by processing a fine pattern of the transmission lens section 2 or a mold obtained by processing a fine pattern of the transmission lens section 2 and the reflection lens section 3 , And a step of molding the above light guide, and a plurality of lenticular unit lenses molded with the same resin as the light guide is formed and formed at the same time.

The applicant of the present application filed a method for manufacturing a light guide for a surface light source or a method for manufacturing a light guide according to Japanese Patent Application No. 7-286046, Japanese Patent Application Laid-Open No. 7-286047, and Japanese Patent Application No. Hei 7-304484 as means for reducing the manufacturing cost of the light guide.

Japanese Patent Application No. 7-286046 and Japanese Patent Application No. 7-286047 disclose that one surface of a flat plate is made to be a light emitting surface and a fine pattern causing a lens action only on this surface is formed and only a mold portion subjected to a fine pattern can be replaced .

In Japanese Unexamined Patent Publication No. 7-304484, in order to perform a light-impermeable treatment on the lower surface of the reflective lens portion 3, a thermal transfer foil is inserted into a mold portion forming a fine pattern of the reflective lens portion 3, The laminated photopaque material thin film is transferred simultaneously with molding by the heat of fusion and the molding pressure of the resin.

Therefore, by applying the present invention to the above-described invention, it becomes possible to make the two lens film sheets, which are heretofore required, unnecessary, and to perform the light-impermeable treatment on the lower surface of the reflective lens portion 3 simultaneously with molding, It is possible to expect a new effect to be connected to a large reduction in the number of users.

As described above, according to the method for manufacturing a light guide and a light guide according to the present invention, since the lenticular lens is formed at the same time as the formation of the lenticular lens, the number of uses of the lenticular lens sheet that is conventionally required is reduced or made unnecessary, The cost can be greatly reduced.

Further, according to the planar light source of the present invention, since the light guide is used, the cost of parts of the planar light source is greatly reduced.

Claims (9)

A light guide body for emitting light emitted from a light source provided adjacent to at least one side end face from a light emission surface, And a first lens unit formed of a plurality of concave or convex lenticular unit lenses molded with the same resin as the light guide member on the light emitting surface, Wherein the plurality of lenticular unit lenses of the first lens unit are prism portions of a triangular prism having an apex angle of 125 to 165 degrees and arranged such that their ridge directions are substantially parallel to each other . The light guide according to claim 1, wherein the angle of the top of the plurality of lenticular lens units of the first lens unit is 135 to 165 degrees. The light guide according to claim 1 or 2, wherein the angle of the apex of the plurality of lenticular unit lenses of the first lens unit is about 150 degrees. 4. The method according to any one of claims 1 to 3, And a second lens portion made of a plurality of concave or convex lenticular unit lenses molded with the same resin as the light guide body on a light reflection surface opposite to the light emission surface, Wherein the plurality of lenticular unit lenses of the second lens unit are prism portions of a triangular prism having an apex angle of 125 to 165 degrees and their ridgeline directions are arranged substantially parallel to each other . 5. The light guide according to claim 4, wherein the angle of the top of the plurality of lenticular lens units of the second lens unit is 135 to 165 degrees. The light guide according to claim 4 or 5, wherein the angle of the top of the plurality of lenticular lens units of the second lens unit is about 150 degrees. The liquid crystal display device according to any one of claims 4 to 6, characterized in that the ridgeline direction of the plurality of lenticular unit lenses of the first lens unit and the ridgeline direction of the plurality of lenticular unit lenses of the second lens unit are arranged to be substantially straight . A light-emitting device according to any one of claims 1 to 7, A light source provided adjacent to at least one side end face of the light guide body And a surface light source. The method of manufacturing a light guide according to any one of claims 1 to 7, And molding the light guide member into a metal mold.