KR20030032575A - Light guide plate for plane light source and manufacturing method thereof0 - Google Patents

Abstract

PURPOSE: A light guide plate for a surface light apparatus and a manufacturing method thereof are provided to improve the quality by projecting diffused light on the front of the light guide plate properly with uniform brightness, and to cut down manufacturing cost with simple structure. CONSTITUTION: A surface light apparatus is composed of a light guide plate(1) transmitting incident rays from the side to the inside; a light source installed at the side of the light guide plate; a diffusion member installed in the front of the light guide plate; and a reflector installed in the light guide plate. Plural diffused reflection parts(2) are formed at the side of a transparent substrate of the light guide plate, and the diffusion pattern surface is formed by forming uneven dots from overlapped or separated fine lines in the diffused reflection part with using a laser beam in forming the light guide plate. Irregular brightness of the surface light apparatus is prevented with forming the diffusion pattern on the diffused reflection part.

Description

Light guide plate for surface light source device and its manufacturing method {LIGHT GUIDE PLATE FOR PLANE LIGHT SOURCE AND MANUFACTURING METHOD THEREOF0}

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 transmissive liquid crystal display device or an illumination plane display device, and a manufacturing method thereof.

Background Art [0002] Conventionally, as a surface light source device used as a surface light source such as a backlight of a transmissive liquid crystal display device or an illumination display device, as shown in FIG. 5, the front surface of the end face 11a of the light transmitting plate 11 having high transparency is shown. The linear light source 12 is disposed, and the diffusion sheet 13 is disposed on the surface side of the light guide plate 11, which is the exit surface, and the reflection sheet 14 is disposed on the rear surface, and more preferably thin. Background Art A surface light source device 10 is known in which lens sheets 15 and 16 having semicircular cross-sections arranged in parallel are superimposed so that the lens strings are arranged to cross in the X and Y directions.

According to this apparatus, the light from the light source 12 enters the light guide plate 11 from the end face 11a, and propagates from the incident end face side toward the reflection side end face while being sequentially reflected from the top and bottom faces. A part of the light propagating through the light guide plate 11 is emitted from the surface of the light guide plate 11 to pass through the diffuser plate 13 to become diffused light to form a uniform luminance plane, and also the lens sheets 15 and 16 It passes through and is condensed in the front direction to become a high brightness surface light source.

However, the above-described luminance plane of the surface light source is bright near the incident end face of the light guide plate 11 and has a drawback that the luminance decreases and becomes dark as it moves away from the incident end face.

In order to solve this drawback, Japanese Patent Application Laid-Open No. 2-157791 discloses, as shown in FIG. 6, it is sparse in the vicinity of the incidence end surface 11a of the light guide plate 11 on the rear surface of the light guide plate 11, and the incidence end surface 11a. It is known to eliminate the diffusion pattern 17 whose area becomes denser as it moves away from the surface of the light guide plate 11 by printing with milky white ink.

It is known that the ink in the printing method is a mixture of fine particles such as medium glass beads containing titanium oxide. However, when such ink is directly printed on the back surface of the light guide plate 11 by silk screen printing, The diffusion pattern, which is formed coarse from the incidence end surface side and gradually densely changes in area, is difficult to form each dot of the annular pattern, for example, in the small area, particularly, and may become a blurry deformation shape.

Moreover, it is difficult to make the size of a dot itself 200 micrometers (phi) or less.

In such a case, there is a problem that the diffusion state of the light propagated by it is not as designed, and as a result, luminance unevenness occurs in the luminance plane 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 the diffusion pattern formed on the bottom of the light guide plate is accurately formed in the molding die of the light guide plate 11, At the same time, a method of transferring and transferring the diffusion pattern accurately as designed is proposed.

In this case, the shaping | molding die of the light guide plate 11 by the shaping | molding system makes it possible to form each dot shape part of the said diffusion pattern by photo etching.

However, in the formation of the diffusion pattern by photoetching, even if the shape of each dot is accurately formed, it is difficult to form the light diffusion surface on the minute uneven surface. In this case, the light diffusion degree is lowered, resulting in a sufficient luminance surface. There is a problem that it is difficult to form.

The present invention provides a light guide plate for use in a surface light source device, such as a backlight of a transmissive liquid crystal or an illumination display device, in forming a diffusion pattern for properly diffusing and radiating light transmitted inside the light guide plate toward the front surface of the surface light source device. An object of the present invention is to solve the above problems.

SUMMARY OF THE INVENTION An object of the present invention is to ensure that the diffused light is properly emitted to the front side of the light guide plate of the surface light source device as designed, and that the entire luminance plane is uniform, and the surface light source device can be manufactured very simply and at low cost. It is to provide a light guide plate for a surface light source device and a manufacturing method thereof.

Another object of the present invention is to provide a light guide plate for a surface light source device and a method of manufacturing the same, which can use a conventionally used dot pattern for printing without luminance unevenness that requires excessive design cost without any effect being reduced. will be.

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

Fig. 2 is a partial cross-sectional explanatory view of a state of manufacturing a light guide plate in the embodiment;

3 is an explanatory diagram of a dot-shaped processed surface for forming a diffuse reflection part in one embodiment of the present invention;

4 is an explanatory diagram of another embodiment of a dot-shaped working surface;

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

6 is a schematic explanatory diagram showing a diffusion pattern state of a diffuse reflection portion provided in the conventional light guide plate;

(Explanation of the sign)

1: light guide plate 1a:

2: diffuse reflection part 3: mold

4: diffuse reflection part forming surface 5, 6: very fine uneven surface of circular dot shape

In order to achieve the above object, the present invention provides a light guide plate for internally propagating light incident from the side, a light source formed on the side of the light guide plate, a diffusion member provided on the front surface of the light guide plate, and installed on the rear surface of the light guide plate In the surface light source device consisting of a reflective member,

The light guide plate is a light guide plate for a surface light source device, characterized in that a plurality of dot-shaped diffuse reflection portions are formed on at least one side of the light-transmissive substrate, and the reflecting portions are diffused surfaces formed by overlapping or separated fine lines from each other.

The present invention further provides a surface light source device comprising a light source on the side, a diffusion member on the front side, and a reflection member on the back side of the light guide plate made of a light-transmissive substrate, wherein the surface of the light guide plate is extremely small. By sending the laser beam of the spot diameter very finely, the diffuse pattern surface in which the dot-shaped diffuse reflection part made of the fine unevenness | corrugation is aggregated is formed, and the said light guide plate at the same time at least one side at the time of the shaping | molding process by the said metal mold | die is the said diffusion pattern It is a manufacturing method of the light-guide plate for surface light source devices characterized by transferring a surface and shape | molding.

Since the diffuse reflection portion of the present invention can form an extremely minute laser spot successively in the longitudinal and transverse directions and form a single dot shape as a result, the processed surface is very fine in each dot itself thus formed. It is formed as an uneven surface. Therefore, light incident on the working surface of the dot is diffusely reflected in all directions uniformly.

If the dot as the diffuse reflection portion is formed on the rear surface side of the light guide plate with the dot shape and the arrangement state of the dot properly, and becomes the diffusion pattern surface, the light incident from the incidence end surface of the light guide plate is propagated to the inside and part of the diffuse reflection portion is Diffuse reflection can be uniformly and suitably satisfactorily, and can be emitted in the front direction to form a predetermined luminance surface.

As a result, the light guide plate of the present invention forms a dot shape in which the diffuse reflection portion is transferred and formed in an appropriate state at the same time when the light guide plate is formed, and has a diffusion pattern in which the dots are collectively arranged, so that the performance of each product is not irregular. It is possible to obtain a light guide plate for a surface light source device having high quality and low mass productivity.

In the manufacture of the light guide plate as described above, a dot shape having a very fine concavo-convex surface is made by sending a laser beam having a very small spot diameter vertically and horizontally to the molding surface of the molding die of the light guide plate in a continuous manner. A diffusion pattern surface having an integrated array of diffusion patterns, wherein the light guide plate has a plurality of dot-shaped diffuse reflection portions composed of extremely fine concavo-convex surfaces on at least the back surface opposite to the exit surface at the same time during molding processing by the mold; Transfer the face to form.

According to this, the dot-shaped diffuse reflection part which consists of the very fine concavo-convex surface of the light-emitting plate surface can be formed easily, uniformly, and appropriately, and the light-guide plate does not produce irregularities in the performance of each product. It can be made into high quality and excellent in low cost mass productivity.

In addition, each dot shape consisting of an extremely fine concave-convex surface of the diffuse reflection portion is formed as a circular, elliptical, square, polygonal, etc. having a minimum width of 50 μm to a maximum width of 1000 μm by hole processing of the molding surface of the molding die with a laser beam. It is desirable to form a diffusion pattern surface in which such dots are collected and transferred to be transferred. As a result, the arrangement design of the diffusion pattern can be easily and appropriately performed, and a light guide plate for a surface light source having a uniform luminance surface can be easily obtained.

In addition, each dot shape consisting of an extremely fine concave-convex surface of the diffuse reflection portion has a molding surface of a molding die with a laser beam having a diameter of 50 to 1000 µm, a cutting depth of 2 to 15 µm, a line pitch of 1 to 20 µm, It is preferable that the diffusion pattern surface formed by forming the horizontally continuous hole processing and collecting such dots is transferred to be molded.

Thereby, the light diffusion of each dot is performed suitably, the function as a diffuse pattern surface of a light guide plate can fully be exhibited suitably, and the light guide plate for surface light source devices which has a uniform brightness surface without luminance nonuniformity is obtained easily. Can be.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described based on drawing.

1 is a partial cross-sectional view for explaining a light guide plate according to an embodiment of the present invention, and FIG. 2 is a partial cross-sectional view for schematically illustrating a state in which the light guide plate is manufactured. FIG. Similar to the light guide plate 11 of FIG. 5, a large number of dot-shaped diffuse reflection portions 2 are formed on the entire surface of the back surface 1a on the opposite side to the emission surface of the predetermined diffusion pattern 17 shown in FIG. 6.

As shown in FIG. 2, the diffuse reflection part 2 of the present invention has a plurality of diffuse reflection part forming surfaces formed in a dot shape made of extremely fine concavo-convex on the surface of the light guide plate of the metal mold 3 forming the light guide plate 1. (4) is simultaneously transferred to form the light guide plate 1 during molding.

The transfer molding surface 4 of the mold 3 which transfers the diffuse reflection part 2 has a spot diameter of 30 to 100 탆, preferably 35 to 60 탆, and a cutting depth of 2 by a laser beam by a laser beam processing machine. It is processed into -15 micrometers, Preferably it is 4-8 micrometers, Line pitch 1-20 micrometers, Preferably it is 1-6 micrometers, and it processes into a very fine uneven surface.

Fig. 3 shows a machining surface for explanation in the case where one dot shape is circularly processed by the laser beam. In this case, the laser beam is moved only in the horizontal direction on the drawing, and as a result, a very fine concavo-convex surface 5 having a circular dot shape having a diameter of 50 to 100 탆 is formed. Fig. 4 similarly shows a machining surface for explanation in the case where the laser beam is moved in the longitudinal and transverse directions on the drawing and processed into the extremely fine concavo-convex surface 6 of a circular dot shape.

The processing surfaces 4 of the diffuse reflection portion 2 of the molding die 3 thus processed are each formed in a precise dot shape by a laser beam, so that a diffusion pattern surface as designed is appropriately formed. The molded light guide plate 1 has a good diffusion surface as designed.

Therefore, the surface light source device using the light guide plate of this invention can be made into the surface light source device of the uniform brightness surface which has the brightness performance equivalent to or more than at least the printing type light guide plate, without generating a luminance nonuniformity.

In the case of the printing light guide plate, in contrast to the difficulty of printing the dot of 0.2 mmφ or less, the laser processing of the present invention makes it possible to easily process 0.05 mmφ, thereby eliminating the dot and field phenomenon.

Moreover, the process by the laser beam of embodiment mentioned above can also be performed by discharge machining.

In addition, the dot shape as the diffuse reflection part of the light guide plate in the above-mentioned embodiment is not limited to a circular shape, It may be shapes other than ellipse, square, polygon, etc., The dot arrangement form of a diffusion pattern can be changed arbitrarily. In addition, the cross-sectional shape of the light guide plate is not limited to the above-mentioned embodiment, and may be rectangular shape, and the formation surface of a diffusion pattern may be provided in the emission surface side or both sides, without being limited to the back surface side of the light guide plate.

(Example)

Hereinafter, a light guide plate for a surface light source device and a manufacturing method thereof according to the present invention will be described, and a comparison with the case where a light guide plate using a printing method is used when the light guide plate for a surface light source device according to the embodiment of the present invention is used. In the example, it is assured that the uniform luminance characteristic of the entire light guide plate exit surface is excellent.

In the embodiment of the present invention, a cross section of acrylic is formed using a wedge-shaped rectangular plate, and a diffuse pattern is formed by processing a laser beam on the rear surface (surface opposite to the exit surface) so that the minute irregularities become a dot shape. In this case, the linear light source is provided opposite to the thick side of the plate thickness to form a surface light source device.

Table 1 shows a part of data specifying the processing conditions when forming a dot shape made of extremely fine unevenness by irradiating a laser beam to the molding die transfer surface of the light guide plate according to the present invention. In this case, data of five samples are shown.

The "output" in this table is the selected display value "line pitch" among the outputs 1 to 127 of the used laser processing apparatus.

"Spot diameter" is the irradiation diameter of the laser beam, "dot shape" is the shape of the dot formed on the irradiation surface by the laser beam scanning, and "processing depth" is the shallowest part of the processing depth of the irradiation surface by the laser beam Indicates the deep part.

"Decision" is a result of the determination of the state of the luminance non-uniformity of the luminance surface when the surface light source device is manufactured using the light guide plate molded by the molding die processed under the above processing conditions.

No. Output (1-127) Line pitch (㎛) Spot diameter (㎛φ) Dot shape Machining Depth / ㎛ Judgment luminance unevenness Shallow profound One 4 3 35 Round 4.0 8.0 ○ 2 10 5 35 Round 6.0 9.0 ○ 3 25 10 70 Round 8.3 10.5 × 4 40 35 70 Round 5.0 10.0 × 5 40 35 70 Round 10.0 22.0 ×

In the molding die 3 of the light guide plate 1 of the present invention, when irradiating and processing a dot-shaped transfer surface made of extremely fine unevenness with a laser beam, the luminance irregularity as the surface light source device is made to be equal to or less than a specified value. As a result of various experiments for selecting the processing conditions, as shown in Table 1, the output of the laser beam processing apparatus 4 to 10, line pitch (feed width) 1 to 12 µm, spot diameter 35 µm φ, beam processing It was found that it is appropriate to carry out at a depth of 4.0 to 9.0 mu m.

If processing is performed under other conditions, for example, the edges of the dot shape are disturbed, the unevenness, that is, the roughness of the surface is not an appropriate value, and the state of the processing surface is not in an appropriate state, and as the surface light source device, The luminance nonuniformity became large and it turned out that it becomes a state beyond specification.

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

In Table 2, the print ink (A), the print ink (B), and the print ink (C) are the luminance values (nit) of the luminance plane of the surface light source device when the printing method light guide plate of the same diffusion pattern using different inks is used. Max, Min, and Typ are the maximum, minimum, and average values of the nine-point measurement data of the luminance plane of each surface light source device, and the uniformity is the ratio (%) of the minimum brightness value to the maximum brightness value. The same applies to the present invention.

Print Ink (A) Print Ink (B) Print Ink (C) Invention Typ 2679 2626 2666 2732 Max 2926 2800 2946 2919 Min 2538 2453 2498 2608 Leveling system 86.7 87.6 84.7 89.3

According to the present invention, since the shaping surfaces of the dot-shaped diffuse reflection portions are precisely formed by the laser beam in the molding die of the light guide plate itself, the diffuse reflection portions are simultaneously formed integrally at the time of forming the light guide plate. The surface light source device using such a light guide plate is properly formed and formed on the light guide plate, and the surface light source device using the light guide plate can be a surface light source device having a uniform luminance surface having at least the same or higher brightness performance than the printing light guide plate without generating luminance unevenness. .

According to the present invention, there is also provided a light guide plate for a surface light source device and a method of manufacturing the same, which can use the printing uniformly conventional dot pattern designed by requiring excessive design cost without any effect reduction.

According to the present invention, in the case of the printing type light guide plate, the printing of the dot of 0.05 mmφ can be easily performed in the laser processing of the present invention, whereas the printing of dot size of 0.2 mmφ or less is difficult. Since the phenomenon of can also be eliminated completely, the surface light source device of the uniform brightness surface excellent also in this point can be made.

Claims (6)

In a surface light source device comprising a light guide plate for propagating light incident from the side surface, a light source provided on the side of the light guide plate, a diffusion member provided on the front surface of the light guide plate, and a reflecting member provided on the rear surface of the light guide plate. , The light guide plate is a light guide plate for a surface light source device, characterized in that a plurality of dot-shaped diffuse reflection portion formed on one side or both sides of the light-transmissive substrate, the reflecting portion is formed of fine lines that overlap or separate from each other. The light guide plate for a surface light source device according to claim 1, wherein the diffuse reflection part has a depth of 1 µm to 15 µm, which is a difference in height. The light guide plate according to claim 1 or 2, wherein the diffuse reflection part has a diameter of 50 µm to 1000 µm and a line pitch of 1 µm to 20 µm. In the manufacturing method of the light guide plate for surface light source devices formed by providing a light source on the side surface, a diffusion member on the front surface, and a reflecting member on the back surface with respect to the light guide plate which consists of a light transmissive substrate, By sending a very small spot diameter laser beam to the molding surface of the molding die of the light guide plate to form a diffusion pattern surface in which the dot-shaped diffuse reflection portion made of very fine unevenness is aggregated, and the light guide plate is formed on the mold. A method of manufacturing a light guide plate for a surface light source device, wherein the diffusion pattern surface is transferred to one or both surfaces at the same time during molding. 5. The dot of claim 4, wherein each dot made of extremely fine irregularities of the diffuse reflection portion is formed by forming a molding surface of a molding die into a dot shape having a minimum width of 50 mu m to a maximum width of 1000 mu m by line processing by a laser beam. A method of manufacturing a light guide plate for a surface light source device, characterized in that the integrated diffusion pattern surface is formed by transfer molding. 6. A dot according to claim 4 or 5, wherein each dot composed of extremely fine irregularities of the diffuse reflection portion is formed by forming a molding surface of a molding die with a laser beam having a diameter of 50 µm to 1000 µm and a line pitch of 1 µm to 20 µm. And a diffusion pattern surface on which these dots are aggregated to be transferred and molded.