JP2001325821A - Photoconductive plate for surface light source device, and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoconductive plate for a surface light source device and its production for permitting proper emission of scattered lights which are designed to the front face of a photoconductive plate in the surface light source device, achieving a uniform and brightness without uneveness over the whole bright surface and allowing an extremely simple and efficient low-cost manufacturing of the surface light source device. SOLUTION: The surface light source device comprises the photoconductive plate for internally propagating a light injected from its side face, the light source provided on the side face of the photoconductive plate, a diffusion member provided on the front face of the photoconductive plate, and a reflecting member provided on the rear face of the photoconductive plate. The photoconductive plate has a diffusing patterned face formed by forming a plurality of uneven, dotted irregular reflection portions on at least the single face of a light transmissive substrate from fine lines overlapped or separated with each other by molding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light guide plate for a surface light source device used for a surface light source such as a backlight of a transmission type liquid crystal display device and an illuminated flat display device, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as a surface light source device used as a surface light source such as a backlight of a transmission type liquid crystal display device or an illumination display device, as shown in FIG. A linear light source 12 is disposed in front of an end face 11a of the light guide plate 11, a diffusion sheet 13 is provided on a front side of the light guide plate 11 which is an emission surface, and a reflection sheet 14 is provided on a back side. And more preferably, a lens sheet 15, 1 in which lenses having a fine cross section having a semi-cylindrical shape are arranged in parallel.
There is known a surface light source device 10 in which lenses 6 are arranged so as to overlap with each other so that their lens strips cross in the X and Y directions. According to this device, the light from the light source 12 is transmitted to the end face 11a.
From the incident end face side while being sequentially reflected on the upper and lower surfaces, and propagates from the incident end face side to the opposite end face direction. A part of the light propagating in the light guide plate 11 is emitted from the surface of the light guide plate 11, passes through the diffusion plate 13 and becomes diffused light to form a uniform brightness surface, and furthermore, a lens sheet. 1
The light passes through 5 and 16 and is condensed in the front direction to become a high-luminance surface light source.

Meanwhile, the luminance surface of the above-mentioned surface light source has a disadvantage that the luminance decreases near the incident end face of the light guide plate 11 and the luminance decreases and becomes darker as the distance from the incident end face increases. In order to solve such a defect, Japanese Patent Laid-Open Publication No.
In the publication No. 1, as shown in FIG. 6, the light guide plate 11 is sparse on the rear surface near the incident end face 11 a of the light guide plate 11,
It is known that the diffusion pattern 17 whose area becomes denser as it gets farther from the incident end face 11a can be eliminated by printing the back surface of the light guide plate 11 with milky white ink.

[0004] Ink for such a printing method includes:
A mixture of fine particles such as glass beads in a medium containing titanium oxide is used. When such an ink is directly printed on the back surface of the light guide plate 11 by silk screen printing or the like, the ink is scattered from the light incident end face side. The diffusion pattern formed so that the area changes gradually and densely, for example, individual round dots forming the pattern are difficult to be accurately formed, particularly in a small area portion, and may have a deformed deformed shape. Also, the dot size itself is 200 μm.
It is difficult to make it less than φ. In such a case, there is a problem that the diffused state of the transmitted light is not as designed, and as a result, luminance unevenness occurs on the luminance surface as the surface light source device.

On the other hand, in order to solve the problem of the printing method, Japanese Patent Application Laid-Open No. Hei 9-138310 discloses that each dot-shaped portion of a diffusion pattern formed on the back surface of a light guide plate is previously formed in a molding die of the light guide plate 11. A method has been proposed in which the diffusion pattern is accurately formed and transferred at the same time as the design, when the light guide plate is formed.

In this case, the molding die of the light guide plate 11 by the molding method is such that the individual dot-shaped portions of the diffusion pattern are formed by photoetching. However, in the formation of a diffusion pattern by photoetching, it is difficult to form a light diffusion surface on a fine uneven surface even if the shape of each dot is accurately formed, in which case the degree of light diffusion is reduced. As a result, there is a problem that it is difficult to form a sufficient luminance surface.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a light guide plate used for a surface light source device such as a backlight of a transmissive liquid crystal or an illumination display device. An object of the present invention is to solve the above-described problems of the related art when forming a diffusion pattern for appropriately diffusing and emitting light.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to ensure that diffused light is properly emitted to the front side of a light guide plate of a surface light source device as designed, and that the entire luminance surface has uniform and uniform luminance. In addition, an object of the present invention is to provide a light guide plate for a surface light source device and a method for manufacturing the same, which can efficiently and efficiently manufacture the surface light source device at a low cost. Another object of the present invention is to provide a surface light source device capable of using a conventionally used dot pattern for printing without luminance unevenness designed at an enormous design cost without any reduction in effect. It is an object of the present invention to provide a light guide plate for use and a method for manufacturing the same.

[0009]

In order to achieve the above object, the present invention provides a light guide plate for internally propagating light incident from a side surface, a light source provided on a side surface of the light guide plate, and a front surface of the light guide plate. In a surface light source device comprising a diffusing member provided on the light guide plate and a reflecting member provided on the back surface of the light guide plate, the light guide plate is formed on at least one surface of the light-transmitting substrate from fine lines which are mutually overlapped or separated by molding. A light guide plate for a surface light source device, wherein a plurality of irregularly-reflected portions in the form of dots are formed to form a diffusion pattern surface. The present invention is also directed to a surface light source device comprising a light guide plate made of a light-transmitting substrate, a light source on a side surface, a diffusion member on a front surface, and a reflection member on a back surface. On the surface, a laser beam having an extremely small spot diameter is extremely finely fed to form a diffusion pattern surface in which irregularly-reflected portions in the form of dots formed of ultrafine irregularities are formed and formed, and the light guide plate is formed by the mold. A method for manufacturing a light guide plate for a surface light source device, wherein the diffusion pattern surface is transferred onto at least one surface at the same time as the molding process.

[0010] The irregular reflection portion of the present invention can be formed as a minute single dot shape while shifting the extremely minute laser spot successively and minutely in the vertical and horizontal directions. In each formed dot itself,
The processed surface is formed as a very fine uneven surface. Therefore, the light incident on the processed surface of the dot is diffusely reflected in all directions without unevenness. If a dot as such a diffuse reflection portion is formed on the back surface of the light guide plate with the dot shape and the arrangement thereof being appropriate and a diffusion pattern surface is formed, the light incident from the incident end face of the light guide plate is internal. The light propagates, and a part of the light is diffused and reflected appropriately and uniformly by the irregular reflection portion, and the light is emitted toward the front surface to form a predetermined luminance surface.

As a result, the light guide plate of the present invention has a diffused pattern in which the irregular reflection portions are transferred and formed in an appropriate state at the same time when the light guide plate is formed, and have a diffusion pattern in which these dots are arranged and arranged. It is possible to provide a light guide plate for a surface light source device which is excellent in mass productivity with high quality and low cost without variation in performance for each.

In manufacturing the light guide plate as described above, a laser beam having an extremely small spot diameter is continuously and finely fed vertically and horizontally to a molding surface of a molding die of the light guide plate. By forming a diffusion pattern surface arranged in an array of dots having an ultra-fine uneven surface, the light guide plate, at the same time at the time of molding by the mold, at least a very fine surface on the back surface opposite to the emission surface. A diffusion pattern surface having a large number of irregularly-reflected portions in the form of dots having irregularities is transferred and molded.

[0013] According to this, it is possible to easily and appropriately form the dot-shaped irregularly-reflected portion formed of the extremely fine uneven surface of the diffusion putter surface of the light guide plate without processing unevenness. There is no variation in the performance of each product, and high quality, low cost and excellent mass productivity can be achieved.

Each of the irregularly-reflected portions, each of which is formed of an extremely fine uneven surface, is formed into a circle, an ellipse having a minimum width of 50 μm to a maximum width of 1000 μm by drilling a molding surface of a molding die with a laser beam. It is preferable to form the shape as a rectangle, a polygon, or the like, and to transfer-mold a diffusion pattern surface on which the dots are arranged. by this,
The arrangement of the diffusion pattern can be easily and appropriately designed, and a light guide plate for a surface light source having a uniform luminance surface without luminance unevenness can be easily obtained.

Further, each dot shape composed of an extremely fine uneven surface of the irregular reflection portion may be formed by a laser beam on a molding surface of a molding die having a diameter of 50 to 1000 μm, a cutting depth of 2 to 15 μm, and a line pitch of 1 to 20 μm. It is preferable to form holes by continuous hole processing in the vertical and horizontal directions so that the diffusion pattern surface on which the dots are arranged and arranged is transferred and formed. As a result, the light diffusion of each dot can be performed properly, and the function as the diffusion pattern surface of the light guide plate can be sufficiently exhibited, and the light guide for a surface light source device having a uniform luminance surface without luminance unevenness. A light plate can be easily obtained.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a partial cross-sectional view illustrating a light guide plate according to an embodiment of the present invention, and FIG. 2 is a partial cross-sectional view schematically illustrating a state in which the light guide plate is manufactured. However, like the light guide plate 11 of FIG. 5 described in the conventional example, the light guide plate 1 has a dot shape with a predetermined diffusion pattern 17 as shown in FIG. A large number of irregular reflection portions 2 are formed.

As shown in FIG. 2, the irregular reflection portion 2 of the present invention is formed on the molding surface of the back surface of the light guide plate of the mold 3 for molding the light guide plate 1 by forming a large number of dots formed of very fine irregularities. Are transferred and formed at the same time when the light guide plate 1 is formed.

The transfer molding surface 4 of the mold 3 for transferring the irregular reflection portion 2 is spotted with a laser beam from a laser beam machine at a spot diameter of 80 to 100 μm, preferably 35 to 60 μm, and a cutting depth of 2 to 15 μm, preferably Processing is performed at 4 to 8 μm, at a line pitch of 1 to 20 μm, and preferably at 1 to 6 μm, to process into an extremely fine uneven surface.

FIG. 3 shows a processing surface for explanation when one dot shape is processed into a circle by the laser beam. In this case, the laser beam is moved and fed only in the horizontal direction in the figure, and as a result, the diameter is 50 to 1000 μm.
An extremely fine uneven surface 5 having a circular dot shape of φ is formed. FIG. 4 shows a processing surface for explanation in the case where the laser beam is similarly moved vertically and horizontally in the drawing to be processed into a very fine uneven surface 6 having a circular dot shape.

The processed surface 4 of the irregular reflection portion 2 of the molding die 3 thus formed is formed in a precise dot shape by the laser beam, so that the diffusion pattern surface as designed is properly formed. Light guide plate 1 formed
Has a good diffusion surface as designed.

Therefore, the surface light source device using the light guide plate of the present invention is a surface light source device having a uniform luminance surface having at least the same or higher luminance performance as the light guide plate of the printing system without causing luminance unevenness. Can be. Also, in the case of a printing type light guide plate, it is difficult to print a dot shape having a size of 0.2 mmφ or less, while the laser processing of the present invention can easily perform 0.05 mmφ processing, thereby making it possible to view dots. Can be completely eliminated.

The processing by the laser beam in the above embodiment can be performed by electric discharge machining. In addition, the dot shape as the irregular reflection portion of the light guide plate in the above-described embodiment is not limited to a circle, but may be an elliptical shape, a rectangular shape, a polygonal shape, or another shape, and the arrangement of the dots in the diffusion pattern can be arbitrarily changed. Further, the cross-sectional shape of the light guide plate is not limited to the above-described embodiment, and may be a rectangular shape, and the surface on which the diffusion pattern is formed may be provided not only on the back surface side of the light guide plate but also on the emission surface side or both.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of a light guide plate for a surface light source device according to the present invention and a method for manufacturing the same will be described, and when the light guide plate for a surface light source device according to the embodiment of the present invention is used, printing will be described. In a comparative example in which a light guide plate of a system is used, it is clarified that uniform luminance characteristics are excellent on the entire light exit surface of the light guide plate.

In the embodiment of the present invention, an acrylic wedge-shaped rectangular plate is used, and its back surface (the surface opposite to the emission surface) is used.
A laser beam is applied to the surface of the substrate to form a diffusion pattern by forming ultra-fine irregularities into a dot shape, and a linear light source is provided on the thicker side of the diffusion pattern to form a surface light source device.

Table 1 shows a part of data for specifying processing conditions for forming a dot shape having extremely fine irregularities by irradiating a laser beam to a molding die transfer surface on the back surface of the light guide plate according to the present invention. It is shown. In this case, data of five samples is shown.

In the table, "output" is a selected scale value of the output 1 to 127 scales of the laser processing apparatus used, and "line pitch" is a selected scale value of the beam feed width.
"Spot diameter" is the irradiation diameter of the laser beam, "Dot shape" is the shape of the dot formed on the irradiation surface by laser beam scanning, and "Working depth" is the shallowest and most processing depth of the irradiation surface by the laser beam. Indicates a deep part.
“Judgment” is the result of judging the state of luminance unevenness on the luminance surface when a surface light source device is manufactured using a light guide plate molded with a molding die processed under the above processing conditions.

Table 1

When the molding die 3 of the light guide plate 1 of the present invention is irradiated with a laser beam on a dot-shaped transfer surface having extremely fine irregularities, the luminance unevenness of the surface light source device becomes equal to or less than a specified value. As a result of performing various experiments for selecting the processing conditions, as shown in Table 1, the outputs 4 to 1 of the laser beam processing apparatus were obtained.
0, a line pitch (feed width) of 1 to 12 μm, a spot diameter of 35 μmφ, and a beam processing depth of 4.0 to 9.0 μm proved to be appropriate.

If the processing is performed under other conditions, for example, the periphery of the dot shape is distorted, or the unevenness state, that is, the surface roughness does not become an appropriate value. , The uneven brightness of the surface light source device increases,
It turned out to be out of standard.

As a result of molding the light guide plate 1 of the present invention using the molding die 3 having the diffusion pattern transfer surface processed by the laser beam processing as described above, the dot shape of the diffusion pattern is appropriately formed as designed. When compared with a surface light source device using a light guide plate having a diffusion pattern formed by a conventional printing method, as shown in Table 2, the uniformity of luminance of the surface light source device using the light guide plate 1 of the present invention is as shown in Table 2. Is clearly higher than the surface light source device of the conventional printing method.

In Table 2, the printing ink A, the printing ink B, and the printing ink C represent the brightness value (nit) of the brightness surface of the surface light source device when a printing type light guide plate of the same diffusion pattern using different inks is used. Show, Max, Min,
Type is the maximum value, the minimum value, and the average value of the nine-point measurement data on the luminance surface of each of the surface light source devices.
It is a ratio (%) of the minimum brightness value to the maximum brightness value. The same applies to the product of the present invention.

Table 2

[0034]

According to the present invention, the forming surface of the dot-shaped irregular reflection portion is accurately formed by the laser beam on the molding die of the light guide plate itself, and the irregular reflection portion is integrally formed at the same time when the light guide plate is molded. Therefore, each diffuse reflection portion is formed on the light guide plate by appropriately configuring the diffusion pattern surface as designed, and the surface light source device using such a light guide plate does not cause uneven brightness, at least. A surface light source device having a uniform luminance surface having luminance performance equal to or higher than that of the printing type light guide plate can be obtained. According to the present invention, a surface light source device which can use a conventionally used dot pattern for printing without luminance unevenness designed at an enormous design cost as it is and without any reduction in effect is used. It is an object of the present invention to provide a light guide plate for use and a method for manufacturing the same. Further, according to the present invention, in the case of a printing type light guide plate, it is difficult to print a dot shape having a size of 0.2 mmφ or less, but with the laser processing of the present invention, it is possible to easily process the same 0.05 mmφ. Since the dot appearance phenomenon can be completely eliminated by this, a surface light source device having an excellent uniform luminance surface can be obtained also in this regard.

[Brief description of the drawings]

FIG. 1 is an explanatory partial cross-sectional view of a light guide plate according to an embodiment of the present invention.

FIG. 2 is an explanatory partial cross-sectional view of a state in which the light guide plate according to the embodiment is manufactured.

FIG. 3 is an explanatory diagram of a dot-shaped processed surface forming an irregular reflection portion according to an embodiment of the present invention.

FIG. 4 is an explanatory view of another embodiment having a different dot-shaped processing surface.

FIG. 5 is an exploded schematic view of a conventional surface light source device using a light guide plate.

FIG. 6 is a schematic explanatory view showing a state of a diffusion pattern of a diffuse reflection portion provided on the conventional light guide plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light-guide plate 1a Back surface 2 Diffuse reflection part 3 Die 4 Diffuse reflection part forming surface 5 Ultrafine irregular surface of circular dot shape 6 Ultrafine irregular surface of circular dot shape

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[Procedure amendment]

[Submission date] October 24, 2000 (2000.10.
24)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction contents]

[0009]

In order to achieve the above object, the present invention provides a light guide plate for internally propagating light incident from a side surface, a light source provided on a side surface of the light guide plate, and a front surface of the light guide plate. In a surface light source device comprising a diffusing member provided on a light guide plate and a reflecting member provided on the back surface of the light guide plate, the light guide plate forms a plurality of dot-shaped irregular reflection portions on at least one surface of the light-transmitting substrate. A light guide plate for a surface light source device, wherein the reflection portion is a diffusion surface formed of fine lines overlapping or separated from each other. The present invention is also directed to a surface light source device comprising a light guide plate made of a light-transmitting substrate, a light source on a side surface, a diffusion member on a front surface, and a reflection member on a back surface. On the surface, a laser beam having an extremely small spot diameter is extremely finely fed to form a diffusion pattern surface in which irregularly-reflected portions in the form of dots formed of extremely fine irregularities are formed and formed, and the light guide plate is formed by the mold. A method for manufacturing a light guide plate for a surface light source device, wherein the diffusion pattern surface is transferred onto at least one surface at the same time as the molding process.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction contents]

The transfer molding surface 4 of the mold 3 for transferring the irregular reflection portion 2 is spotted with a laser beam from a laser beam machine at a spot diameter of 30 to 100 μm, preferably 35 to 60 μm, and a cutting depth of 2 to 15 μm, preferably Processing is performed at 4 to 8 μm, at a line pitch of 1 to 20 μm, and preferably at 1 to 6 μm, to process into an extremely fine uneven surface.

Claims (6)

[Claims] 1. A light guide plate for internally propagating light incident from a side surface, a light source provided on a side surface of the light guide plate, a diffusion member provided on a front surface of the light guide plate, and a reflection member provided on a back surface of the light guide plate. In the surface light source device comprising a member, the light guide plate is formed on at least one surface of the light-transmitting substrate by forming a plurality of irregularly-reflected irregularities in the form of irregularities from fine lines which are mutually overlapped or separated by molding, and a diffusion pattern surface. A light guide plate for a surface light source device, comprising: 2. The irregular reflection section has a depth of 1 μm to 15 μm.
2. The light guide plate for a surface light source device according to claim 1, wherein: 3. The irregular reflection part has a diameter of 50 μm to 100 μm.
3. The light guide plate for a surface light source device according to claim 1, wherein the light guide plate has a thickness of 0 μm and a line pitch of 1 μm to 20 μm. 4. A method of manufacturing a light guide plate for a surface light source device, comprising: a light source on a side surface, a diffusion member on a front surface, and a reflection member on a back surface of a light guide plate made of a translucent substrate. On a molding surface of a molding die, a laser beam having an extremely small spot diameter is extremely finely fed to form a diffusion pattern surface in which dot-shaped irregular reflection portions composed of ultrafine irregularities are formed and formed, and the light guide plate is formed. A light guide plate for a surface light source device, wherein the diffusion pattern surface is transferred onto at least one surface at the same time as molding by the mold. 5. Each of the dots composed of extremely fine irregularities of the irregular reflection portion is formed in a dot shape having a minimum width of 50 μm to a maximum width of 1000 μm by line processing using a laser beam on a molding surface of a molding die. 5. The method for manufacturing a light guide plate for a surface light source device according to claim 4, wherein the formed diffusion pattern surface is formed by transfer molding. 6. Each dot composed of extremely fine irregularities of said irregular reflection portion has a diameter of 50 μm to 1000 μm and a line pitch of 1 μm to 2 μm on a molding surface of a molding die by a laser beam.
6. The method of manufacturing a light guide plate for a surface light source device according to claim 4, wherein dots are formed by 0 [mu] m, and a diffusion pattern surface formed by integrating the dots is transferred and molded.