KR100253635B1 - Light guiding body, method of manufacturing thereof, and plane-light source - Google Patents

Abstract

Disclosed is a surface light source for a backlight which reduces the number of use of the lenticular lens sheet or further eliminates the component cost and manufacturing cost, a light guide provided with the surface light source, and a method of manufacturing the light guide.

The light guide 1 is formed with a transmission lens portion 2 made of a plurality of lenticular unit lenses molded of the same resin as the light guide 1. The lenticular unit lens of the transmission lens part 2 is a prism of a concave or convex triangular pillar, and these ridge directions are arranged substantially parallel to each other. Further, the vertex angle of the prism of the triangular pillar is formed from 125 degrees to 165 degrees. The light-opaque treatment is performed on the surface opposite to the transmission lens part 2 so that light does not transmit.

Description

LIGHT GUIDING BODY, METHOD OF MANUFACTURING THEREOF, AND PLANE-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 surface light source. More specifically, the present invention relates to a surface light source used for a backlight such as a liquid crystal display device, an illumination advertisement, a traffic sign, and the like; And a method for producing the light guide.

As a surface light source for backlight of a liquid crystal display device (LCD), the thing of the edge light system which uses a translucent flat plate as a light guide is known. As such a surface light source, light is incident on 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 using total reflection inside the light transmissive plate, and a part of the propagated light is transferred. The light scattering reflector on the back surface of the light guide is made of diffused reflected light below the critical angle to emit diffused light from the surface of the light guide (actual locations 55-162201).

In addition, a lens sheet having a projection of a triangular prism type lenticular lens on one surface and a smooth surface on the other surface is superimposed on the surface of the light guide of the surface light source described above, and the light focusing action of the lens is used. It is also known that the diffused radiated light can be uniformly diffused in a desired angle within the desired angle range (Platform 4-107201).

When the lens sheet is used in combination with a chlorine transparent diffuser plate (chlorine transparent sheet), rather than simply using a chlorine transparent diffuser plate (US Pat. No. 4,472,067), the lens sheet focuses on the light energy of the light source within a desired limited angle range. In addition, within the angular range, it is possible to obtain diffused light having high uniform isotropy.

Moreover, in recent years, as a countermeasure for the high brightness of the backlight used for a liquid crystal display device, as shown in FIG. 1, it has a tendency to adopt the structure which overlapped two lenticular lens sheets at right angles (Monthly display, May 1996 issue P35-P39). .

However, the backlight of the conventional liquid crystal display device not only has a problem that the visual characteristics are relatively narrow, but also uses two lenticular lens sheets, so that component cost is incurred, and two lenticular lens sheets are used. Since it is necessary to mount the mounting at right angles, there is a lot of manufacturing costs, there is a problem that the backlight itself becomes very expensive.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the surface light source for backlight and the surface light source which reduce the component cost and manufacturing cost by making the number of use of the lenticular lens sheet into one sheet or furthermore unnecessary are provided. An object of the present invention is to provide a light guide and a manufacturing method of the light guide.

The light guide of the present invention according to claim 1 is a light guide that emits light emitted from a light source disposed adjacent to at least one side cross section from a light emitting surface in order to achieve the above object. A first lens unit comprising a plurality of concave or convex lenticular unit lenses molded of the same resin as the light guide, wherein the plurality of lenticular unit lenses of the first lens unit have a triangular angle of 125 degrees to 165 degrees at the top As the prism portion of the pillar, their ridge directions are arranged substantially parallel to each other.

The light guide of the present invention according to claim 2 is characterized in that, in the light guide according to claim 1, angles of the tops of the plurality of lenticular unit lenses of the first lens portion are 135 degrees to 165 degrees.

The light guide according to claim 3, wherein the light guide according to claim 1 has an angle of about 150 degrees at the top of the plurality of wrench circular unit lenses of the first lens section.

The light guide of the present invention according to claim 4 is a light guide that emits light emitted from a light source disposed adjacent to at least one side cross section from a light emitting surface, the light emitting surface being made of the same resin as the light guide. A plurality of lenticular unit lenses formed of a plurality of concave or convex shaped lenticular unit lenses are formed, wherein the plurality of lenticular unit lenses of the first lens unit are triangular prism portions having a top angle of 125 to 165, and their ridge direction is A second lens portion formed of a plurality of concave or convex lenticular unit lenses formed of the same resin as the light guide member on a light reflection surface disposed substantially parallel to each other and opposite to the light emitting surface; The plurality of lenticular unit lenses are triangular prism portions having an angle of 125 to 165 degrees at the top, and their ridge directions are arranged substantially parallel to each other. That is characterized.

The light guide of the present invention according to claim 5 is the light guide according to claim 4, wherein the angles of the top portions of the plurality of lenticular unit lenses of the first lens portion are 135 degrees to 165 degrees.

The light guide according to claim 6 is the light guide according to claim 4, wherein the light guide according to claim 4 includes a ridge line direction of a plurality of lenticular unit lenses of the first lens unit and a ridge line of a plurality of lenticular unit lenses of the second lens unit. It is characterized in that the directions are arranged to be substantially parallel to each other.

The light guide of the present invention according to claim 7 is characterized in that, in the light guide according to claim 4, angles of the tops of the plurality of lenticular unit lenses of the second lens portion are 135 degrees to 165 degrees.

The light guide of the present invention according to claim 8, wherein the top of the plurality of lenticular unit lenses of the first lens portion is 150 degrees around the light guide according to claim 4.

The light guide of the present invention according to claim 9, wherein the top of the plurality of lenticular unit lenses of the second lens portion is 150 degrees around the light guide according to claim 4.

The surface light source of the present invention according to claim 10 comprises the light guide according to any one of claims 1 to 9, and a light source provided adjacent to at least one side cross-section of the light guide. do.

The method of manufacturing a light guide according to claim 11, wherein the method of manufacturing a light guide according to any one of claims 1 to 9 includes a step of molding the light guide into a mold. It is done.

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 of a light guide according to the present invention;

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

7 (a) and 7 (b) are perspective views showing the light guide member.

8 (a), 8 (b), and 8 (c) are schematic diagrams showing the cross-sectional shape of the prism portion of the triangular pillar.

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

<Description of the code | symbol about the principal part of drawing>

1: light guide

1a: side cross section

1b: Lenticular unit lens

2: transmission lens

3: reflective lens unit

4: light source

5: surface light source

6: liquid crystal panel

Embodiment of this invention is described in detail with drawing.

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

The lenticular unit lens refers to a prism of a triangular pillar whose base is a triangle formed by the vertex ABC in FIG. 7A, and a prism of a pentagonal pillar whose base is a pentagon formed by the vertex ABDEC in FIG. 7B. However, the lenticular unit lens 1b illustrated here is merely an example, and is not limited thereto. Also, in this figure, the lenticular unit lens shows only a convex shape. However, although not shown, a concave shape may be used.

The prism portion of the triangular pillar of the lenticular unit lens refers to a prism of a triangular pillar having a triangle formed of vertex ABC as a bottom face in both FIGS.

The top of the prism portion of the triangular pillar refers to the vertex A in Figs. 7A and 7B.

The angle of the top part of the prism part of a triangular column means the angle which the point BAC makes in FIG. 7A and FIG. 7B.

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

The prism portion of the triangular pillar is preferably an isosceles triangle shape as shown in Fig. 8A, but for example, the top portion A is slightly shorted as shown in Fig. 8B to form a quadrangle shape, or the top portion A is smooth as shown in Fig. 8C. Since the curved shape has little effect on the performance of the light guide, these prisms of all shapes are included in the prism portion of the triangular pillar of the present invention.

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

The light guide 1 is formed with a transmission lens portion 2 composed of a plurality of lenticular unit lenses molded of the same resin as the light guide 1. On the opposite surface of the transmissive lens portion 2, light reflection treatment (for example, fine unevenness or screen printing, such as fine irregularities or screen printing) is performed to diffuse light diffusely and uniformly, or to provide light In order to prevent leakage, a reflector is installed in a subsequent process (not shown).

The lenticular unit lens of the transmission lens part 2 is a prism of a triangular column, and the direction of these ridges are arranged substantially parallel to each other, and in particular, the vertex angle of the prism of the triangular column is from 125 ° to 165 ° based on the calculation result described later. It is manufactured to become a range. Further, if the vertex angle of the prism of the triangular prism is in the range of 125 ° to 165 °, even if the size, pitch, height and vibration or fluctuations of the prism of the triangular prism are caused, the performance of the light guide is not affected. In particular, as shown in Fig. 9, it can be seen that the luminance distribution characteristic does not change significantly even when the pitch of the prism is changed in the range of 10 µm to 1000 µm.

The material of the light guide 1 is selected from light transmitting materials. Usually, acrylic or polycarbonate resin is used. As for the thickness of a light guide, the thing of about 1-10 mm is used normally.

In addition, other light-transmissive materials include polyesters such as polyethylene esters such as methyl polyacrylate and methyl polyacrylate, or copolymers of methacrylic esters, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polycarbonates and polystyrene. Thermoplastic resins such as polymethylpentine, polyfunctional urethane acrylates crosslinked with ultraviolet rays or electron beams, acrylates such as polyester acrylates, transparent resins such as unsaturated polyesters, transparent glass, transparent ceramics, and the like.

Next, the operation of the light guide according to the present invention will be described with reference to FIG. 2.

Light emitted from a light source (not shown) provided adjacent to the side end face 1a of the light guide 1 (horizontal right side in FIG. 2) enters the inside of the light guide 1 from the side end face 1a and is transmitted. Reflected from the opposite surface of the lens portion 2 or the side surface other than the side cross-section 1a, the light guided in the direction of the transmissive lens portion 2 has a function of focusing the light and spreads the diffused emission light within a desired angle range. It exits from the transmission lens part 2 which spreads uniformly in an isotropic form (up direction of FIG. 2).

3 is a graph showing luminance distribution characteristics.

The horizontal axis represents the position of the light guide from the lamp in percent, with the length of the light guide being 100 percent, where the value 0 is the position of the end face of the light guide closest to the lamp, while the value 100 is the lamp. Is the end face position of the light guide furthest from.

Although the vertical axis does not represent a unit, the larger the value, the brighter.

3 is a graph illustrating luminance distribution characteristics of the light guide body using CODEV, an optical design evaluation software developed by ORA, USA. The evaluation parameters include 600 nm, As the material of the light guide, the refractive index of the representative PMMA is 1.49, and the vertices of the triangular prism are 90 °, 120 °, 125 °, 150 °, 165 °, and flat (i.e., no prism of the triangular column). The simulation result of the luminance distribution characteristic in the case of change to) is shown.

As apparent from this figure, the luminance distribution characteristic of the vertex angle of 90 ° to 120 ° of the lens sheet used with the conventional light guide is not only inferior to flat but also 125 ° to 165 °. The luminance distribution characteristic of is significantly improved compared with the conventional luminance distribution characteristic from 90 degrees to 120 degrees. In addition, the characteristic improvement from 135 ° to 165 ° is remarkable, and it can be easily understood that the peak effect is exhibited in the luminance distribution characteristic especially in the vicinity of 150 °.

However, even if the wavelength of light and the refractive index of a light guide material are changed somewhat, there is no big influence on the luminance distribution characteristic revealed here. In addition, the applicant of the present application deviated from the stereotype of 90 ° to 120 °, which is the vertex angle of the conventional lens sheet, and independently performed basic optical design simulation of the light guide, and as a result, the luminance distribution characteristic was changed from 125 ° to 165 °. We found a significant improvement in the range, and based on the results, we proposed a completely new light guide plate.

4 is a graph showing viewing angle characteristics.

The horizontal axis represents the 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 vertical axis does not show the unit, the larger the value as luminance, the brighter.

The graph showing the viewing angle characteristic of FIG. 4 is an analysis of the viewing angle characteristic of the light guide using CODEV as described above. As an evaluation parameter, the wavelength of the light irradiated from the lamp is 600 nm and the PMMA representative of the light guide is used. Luminance distribution when the vertex angle of the prism of the triangular prism is changed to 90 °, 120 °, 125 °, 135 °, 150 °, 165 °, and flat (i.e. without the prism of the triangular prism) using a refractive index of 1.49. The simulation result of the characteristic is shown.

As is apparent from this figure, when the viewing angle characteristic of the vertex angle of 90 degrees and the viewing angle characteristic of 120 degrees of the lens sheet used with the conventional light guide body are compared, 120 degrees are far worse than 90 degrees. On the other hand, the viewing angle characteristic from 125 degrees to 165 degrees is much improved compared with the conventional viewing angle characteristic of 90 degrees, and it can easily understand that a peak effect is shown.

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

The light guide 1 is formed with a transmissive lens portion 2 and a reflective lens portion 3 made of a plurality of lenticular unit lenses molded from the same resin as the light guide 1.

The lenticular unit lenses of each of the transmissive lens unit 2 and the reflective lens unit 3 are prisms of a triangular prism, and their ridge directions are arranged substantially parallel to each other, and the ridge lines of the plurality of lenticular unit lenses of the transmissive lens unit 2 are arranged. Direction and the ridge line direction of the plurality of lenticular unit lenses of the reflective lens unit 3 are arranged to be substantially parallel to each other.

In addition, the reflecting surface treatment by aluminum vapor deposition etc. is performed in the lower surface of the reflective lens part 3 so that light may not permeate | transmit (not shown).

Next, the operation of the light guide according to the present invention will be described with reference to FIG. 5.

Light emitted from a light source (not shown) provided adjacent to the side end face 1a of the light guide 1 (horizontal right direction in FIG. 5) enters the inside of the light guide 1 from the side end face 1a, It reflects from the lower surface of the reflective lens part 3 or the side surface other than the side surface 1a. At this time, the reflective lens portion 3 serves to equalize the light guided by the transmission lens portion 2 in the light guide 1 and guides the diffused light in the direction of the transmission lens portion 2.

The light guided by the reflective lens unit 3 in the direction of the transmission lens unit 2 has a function of focusing the light, and transmits the diffuse lens unit uniformly isotropically in the desired angle range within the desired angle range ( It exits from 2) (the upward direction of 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 composed of a liquid crystal panel 6 and a surface light source 5, the surface light source 5 is a light guide 1 according to the present invention, a light source 4 such as a fluorescent tube, and various control circuits ( Not shown).

The light emitted from the light source 4 enters from the side end surface of the light guide 1 and is reflected at the side end surface other than the bottom surface or the side end surface of the reflective lens unit 3, and the focus is repeated, and the diffuse radiation is desired. It is uniformly diffused in the angular range and guided to the liquid crystal panel 6.

Moreover, in the manufacturing method of the light guide body which concerns on this invention, the metal mold | die which processed the micropattern of the transmission lens part 2, and the metal mold | die which processed the micropattern of the transmission lens part 2 and the reflective lens part 3 is processed. And forming a plurality of lenticular unit lenses formed of the same resin as the light guide, by forming the aforementioned light guide.

In addition, the present applicant has applied for a method for manufacturing a light guide for a surface light source or a light guide according to Japanese Patent Application No. 7-286046, Japanese Patent Application No. 7-286047, and Japanese Patent Application No. 7-304484 as one means of reducing the manufacturing cost of the light guide. Was done.

In Japanese Patent Application No. 7-286046 and Japanese Patent Application No. 7-286047, one side of the flat plate is used as the light emitting surface, and only the mold part having the fine pattern can be replaced while forming a fine pattern that causes the lens action only on this surface. have.

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

Therefore, by applying the present invention to the above invention, it becomes possible to eliminate two lens film sheets required in the prior art, and to perform light impermeability treatment on the lower surface of the reflective lens portion 3 simultaneously with molding. New effects can be expected, leading to a significant reduction in manufacturing costs.

As described above, according to the light guide according to the present invention and the method of manufacturing the light guide, since the lenticular lens is formed at the same time as the molding, the number of use of the lenticular lens sheet required in the prior art can be reduced or further eliminated. As a result, the manufacturing cost can be greatly reduced.

Moreover, according to the surface light source which concerns on this invention, since the said light guide body is used, the component cost of surface light source is drastically reduced.

Claims (11)

A light guide for emitting light emitted from a light source disposed adjacent to at least one side cross section from a light emitting surface, A first lens unit comprising a plurality of concave or convex lenticular unit lenses molded on the light emitting surface of the same resin as the light guide; Provided with The plurality of lenticular unit lenses of the first lens portion is a prism portion of a triangular prism having an angle of 125 degrees to 165 degrees at the top thereof, and the direction of their ridges is arranged substantially parallel to each other. The method of claim 1, The light guide of claim 1, wherein the angles of the top portions of the plurality of lenticular unit lenses are 135 degrees to 165 degrees. The method of claim 1, The light guide of claim 1, wherein an angle of the tops of the plurality of wrench circular unit lenses of the first lens unit is about 150 degrees. A light guide for emitting light emitted from a light source disposed adjacent to at least one side cross section from a light emitting surface, A first lens unit comprising a plurality of concave or convex lenticular unit lenses molded on the light emitting surface of the same resin as the light guide; Provided with The plurality of lenticular unit lenses of the first lens unit are triangular prism portions having an angle of 125 to 165 at the top thereof, and their ridge directions are substantially parallel to each other. A second lens portion comprising a plurality of concave or convex lenticular unit lenses molded of the same resin as the light guide member on a light reflection surface opposite the light emitting surface; The plurality of lenticular unit lenses of the second lens portion are triangular prism portions having an angle of 125 to 165 degrees at the top thereof, wherein the ridge lines thereof are arranged substantially parallel to each other. The method of claim 4, wherein The angle of the top portion of the plurality of lenticular unit lenses of the first lens unit is a light guide, characterized in that 135 degrees to 165 degrees. The method of claim 4, wherein And the ridge lines of the plurality of lenticular unit lenses of the first lens unit and the ridge lines of the plurality of lenticular unit lenses of the second lens unit are arranged to be substantially perpendicular to each other. The method of claim 4, wherein The angle of the top portion of the plurality of lenticular unit lenses of the second lens unit is a light guide, characterized in that 135 degrees to 165 degrees. The method of claim 4, wherein The angle of the top of the plurality of lenticular unit lenses of the first lens unit is around 150 degrees. The method of claim 4, wherein The light guide of claim 2, wherein an angle of the tops of the plurality of lenticular unit lenses of the second lens unit is about 150 degrees. The light guide according to any one of claims 1 to 9, A light source disposed adjacent to at least one side surface of the light guide; Surface light source comprising a. In the manufacturing method of the light guide of any one of Claims 1-9, Molding the light guide into a mold Method for producing a light guide, characterized in that it comprises a.

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