JPH056401U - Light guide device - Google Patents

Abstract

(57) [Summary] [Purpose] An ultra-thin (2 mm or less) light guide 1 which is flexible and does not reduce the brightness value on the surface of the light guide 1. An object is to provide an optical device. [Structure] Diffuse to the prism surface 4 side of an ultra-thin light guide body 1 composed of a single member with the front surface being a prism surface 4 with a large number of ridges 3 arranged in a corrugated shape and the back surface being a smooth surface Film 8
The reflective film 6 is provided on the smooth surface 5 side, and the light from the light source 2 is made incident on the light guide 1 from at least one end face of the light guide 1, and the light is reflected by the reflective film 6. The prism surface 4 side is made to emit light, and the shape of the cross section of the ridge portion 3 of the prism surface 4 has an apex angle θ of 75 ° to 90 °.
Is an isosceles triangle.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

  The present invention is a backlight used for displays such as LCD TVs and personal computers. , Notebook type, book type, laptop type, palm type The present invention relates to a light guide device used as a liquid crystal display panel of a portable personal computer of a pull type or the like.

[0002]

[Prior art]

  The conventional light guide device includes a light guide plate 21 made of acrylic resin or the like as shown in FIG. The light guide plate 21 has a reflecting surface 25 for reflecting and blocking the light incident from the edge portion. And a light emitting surface 24 for emitting the light, and a poly A light-shielding sheet 26 in which the inner surface of an ethylene film is vapor-deposited with silver is adhered, and the light guide plate 21 The back side of the product has 27 treatments such as scratches and screen printing to make the light uniform. On the other hand, a diffusion film 28 for diffusing light is attached to the light emitting surface 24 side, The surface of this diffusion film 28 is embossed (textured) 30 etc. There was

[0003]

[Problems to be solved by the device]

  The light guide plate 21 of the light guide device is made of a plate resin made of acrylic resin or the like. Therefore, the total thickness is at least about 2 mm, and it is not flexible and easily cracks. In addition, the diffusion film 28 and the embossing 30 spread the light in each direction. The lighter the light guide plate 21 becomes, the less light comes out to the front. And the brightness value was considerably reduced. Moreover, recently, a portable personal computer, that is, no With the widespread use of computers such as laptop and book computers, thin and lightweight light guide devices are required. Has been.

[0004]   Therefore, the present invention uses an ultra-thin (2 mm or less) light guide, which is flexible and Provided is a light guide device in which the brightness value on the surface of the light guide is not reduced. The purpose is to

[0005]

[Means for Solving the Problems]

  The present invention takes the following technical means in order to achieve the above object.

[0006]   That is, the front surface was a prism surface with a large number of ridges arranged in a wave pattern, and the back surface was a smooth surface. A diffusion film is smoothed on the prism side of the ultra-thin light guide composed of a single member. At least one side end surface of the light guide while providing a reflection film on each surface side. The light from the light source enters into the light guide, and the light is reflected by the reflective film to form a prism. The surface side is made to emit light, and the cross-sectional shape of the ridge portion of the prism surface has an apex angle θ. Is an isosceles triangle of 75 ° to 90 °.

[0007]

[Action]

  In the light guide device according to the present invention, the light incident from at least one end face of the light guide 1 is Are reflected by the prism surface 4 and condensed by the prism surface 4, and as shown by the arrow in FIG. Light is emitted from the part 3 in a unidirectional and constant angle within the inclination angle of the prism surface 4. Therefore, even if the light guide body 1 is made ultra-thin and the weight is reduced, the brightness does not decrease. Also, since the whole is thin like a film, it is freely deformable and hard to break, Flexible light guide that can be stored, is suitable for all purposes and is easy to use It became a device.

[0008]

【Example】

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

[0009]   The light guide device according to the present invention, as shown in FIGS. Single part made of transparent film with good light transmittance such as Bonate, AS, PET A light guide 1 formed of a material, and a light source 2 arranged on both sides thereof or on one end face thereof with a space therebetween. Is equipped with.

[0010]   The surface of the light guide 1 is a prism surface 4 in which a large number of ridges 3 are arranged in a corrugated form, and Is a smooth surface 5, and the smooth surface 5 diffuses light and diffuses it uniformly. Scratch-like processing 7 such as scratches and screen printing has been applied. Also this smooth surface On the 5 side, to prevent light leakage, for example, a silver vapor deposition film is formed on the inner surface of a polyethylene film. The reflection film 6 formed by attaching the rum is attached. On the other hand, the prism surface 4 side Is semi-transparent with high transmittance so that the state of processing 7 such as screen printing is not reflected in Diffusion film 8 which is a single or multiple polymerized polycarbonate film It is provided.

[0011]   On the other hand, as the light source 2, a high brightness one such as a hot cathode discharge tube has been used conventionally. However, as mentioned above, the light source 2 is also a small cold cathode discharge that corresponds to the thinner and lighter light guide. Pipes are often used, for example, those with a diameter of 3 mm to 6 mm are used. .

[0012]   Also, covering the outer periphery of the light guide 1 to the light source 2 is, for example, a vinyl chloride film or the like. Is provided with a light-shielding cover 9 made of silver or gold colored foil on its inner surface. , Aluminum foil, aluminum coated silver paper, aluminum coated film, etc. Affixed to prevent light from the light source 2 from leaking.

[0013]   The shape of the cross section of the ridge portion 3 which constitutes the prism surface 4 is such that the apex angle θ is 75 ° to 90 °. Densely cut isosceles triangles are preferred, as the precision increases It is possible to prevent la. Also, this angle θ depends on the material forming the light guide 1. Since the refractive index is different, it is selected accordingly.

[0014]   If the apex angle θ is smaller than 75 °, the interval between the ridges 3 becomes too narrow and the light does not enter. This is not preferable because the irradiation range becomes narrower and the light amount decreases, and the angle θ is large. If the brightness is higher when the threshold is higher than 90 °, the efficiency of focusing light forward becomes extremely high. It is not preferable because it decreases.

[0015]   The light guide 1 has a total thickness a of 0.5 to 2. The height b of the ridge 3 is about 0.2 mm and the width c is about 0.4 mm. Is preferred. In addition, whether the smooth surface 5 is obtained by subtracting the height b of the protrusion 3 from the total thickness a. If the height a-b is 0.3 mm or less, the light input from the light source 2 will be poor. Absent. In addition, in order to improve the light diffusion and condensing effect as in the above, the height of the protrusion 3 should be It is preferable that b is 1/3 to 1/2 of the width c of the protrusion 3.

[0016]   If it goes out of each of the above ranges, the incident light cannot be emitted from the prism surface 4. The light is reflected again in the light guide 1 and the luminous efficiency is reduced, so that high brightness cannot be obtained. .

[0017]   In addition, as shown in FIG. 1, the protrusion 3 is arranged in the direction in which the light source 2 is arranged. It is preferable to install it in a direction orthogonal to it, because the viewing angle becomes wide.

[0018]   The light guide 1 composed of a single member according to the present invention is a prism under the above conditions. Since it constitutes the surface 4, the light diffused by the reflection film 6 is reflected by this The light is condensed on the prism surface 4 and emitted in one direction and at a constant angle.

[0019]   Next, the brightness of the concrete example of the present invention shown in FIGS. 1 and 2 and the conventional example shown in FIG. The measurement results will be described.

[0020]   In addition, the light guide device in the concrete example of the present invention and the conventional example is made of the material of the light guide 1. Of the same size, light source type, number, strength, etc. The light guide device used is as described below.

[0021]   <Specific examples>     Light guide thickness a: 1.5 mm     Overall size: 200 mm x 140 mm     Type and number of light sources: Short-side light input, 1 cold cathode discharge tube (φ4.8 mm)     Vertical angle of ridge θ: 90 °     Height of ridge b: 0.2 mm     Width of ridge c: 0.4 mm

[0022]   <Comparative example>     Light guide plate thickness d: 2.5 mm     Overall size: 200 mm x 140 mm     Type and number of light sources: Short-side light input, 1 cold cathode discharge tube (φ4.8 mm)

As described above, using two different kinds of light guide devices, the brightness comparison measurement is performed by using the vertical axes I, II and III and the horizontal axes X, Y and Z on the effective light emitting surface shown in FIG. The following table shows the average brightness as an index. The unit of numerical values in the table is cd / m ² .

[0024]

[Table 1]

As a result of the comparative measurement in the above table, the overall average brightness in the example is 326 cd / m ² , the overall average brightness in the conventional example is 321 cd / m ² , and the overall thickness a of the present invention is considerably thin. It can be seen that even if the light guide device is used, the prism surface 4 does not lower the luminance.

[0026]   In the above luminance measurement, as shown in FIG. 1, only one side end of the light guide 1 is set as the incident surface 11. However, the other side end is a short side single lamp type that does not have the light source 2 as the light shielding surface 12 that shields light. Although it was done with the same thing, the same applies to the case of the two-lamp type in which the light source 2 is provided opposite to both ends. It was the result.

[0027]

[Effect of device]

  In the light guide device according to the present invention, a large number of ridges 3 are arranged on the surface of the prism surface in a corrugated form. 4 and the prism of the ultra-thin light guide 1 composed of a single member with the back surface being a smooth surface 5. The diffusion film 8 is provided on the side of the smooth surface 4 and the reflection film 6 is provided on the side of the smooth surface 5, The cross-sectional shape of the ridge 3 on the prism surface 4 is an isosceles triangle with an apex angle θ of 75 ° to 90 °. Therefore, the light from the light sources 2 arranged on both sides of the light guide 1 or one end face is The light enters the light guide 1, is reflected, etc., and is condensed by the prism surface 4. The light is emitted in one direction and at a constant angle within the tilt angle of the prism surface 4.

[0028]   Therefore, even though the light guide 1 is ultra-thin (2 mm or less) and lightweight as described above, Since there is no decrease in brightness and the entire film is thin, Flexible, free to transform, hard to break, can be stored anywhere and easy to use, It became flexible.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of the same portion.

FIG. 3 is a front view showing measurement points of the same brightness.

FIG. 4 is a partially enlarged cross-sectional view showing a conventional example.

[Explanation of symbols]

1 Light guide 2 light sources 3 ridges 4 prism surface 6 reflective film 8 diffusion film θ Vertical angle of ridge a Thickness of light guide b Height of ridge c Width of ridge

Claims (2)

[Scope of utility model registration request] 1. An ultra-thin light guide body composed of a single member whose front surface is a prism surface (4) in which a large number of ridges (3) are arranged in a corrugated shape and whose rear surface is a smooth surface (5). The diffusion film (8) on the prism surface (4) side of 1) and the reflection film (6) on the smooth surface (5) side.
And the light from the light source (2) enters the light guide (1) from at least one end face of the light guide (1), and the light is reflected by the reflection film (6) to form a prism surface. (4) A light guide device, characterized in that the side is made to emit light. 2. The cross-sectional shape of the ridge (3) of the prism surface (4) is an isosceles triangle having an apex angle (θ) of 75 ° to 90 °. Light guide device.