JP2000066029A - Production of light transmission plate and production of metal mold utilizing the light transmission plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to easily, inexpensively and rapidly form a trial plate for prior evaluation and check by processing light-scattering patterns consisting of many recessed parts on the surface of a resin plate directly irradiated with a laser beam. SOLUTION: A laser beam 5 is emitted in compliance with control conditions by a command from a personal computer 2 and is condensed to the front surface of the resin plate 8 by a condenser lens 4 via a scan mirror 6 in such a manner that the condensed spot thereof is minimized. The resin plate 8 is installed on an X-Y precision moving table 7 and moves in compliance with the output from the personal computer 2. The laser beam 5 instantaneously vaporizes the resin of the front surface 8a of the resin plate 8 and forms the recessed parts by the scanning with the scan mirror 6 and the on-off of a laser beam irradiation device 3. The shapes in the plane direction of these recessed parts are free and the depth thereof is free by the intensity and time of the irradiation with the laser beam. These light scattering patterns (the number, arrangement, etc., of the recesses) and their shapes, depths and sizes are freely set by inputting of data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a synthetic resin light guide plate which is used as a surface illumination device and has a large number of recesses, on which a pattern for scattering light incident from a light source is formed. The present invention relates to a method for manufacturing a light guide plate mold using a light plate.

[0002]

2. Description of the Related Art Conventionally, as one method of producing a synthetic resin light guide plate, there is a method of using a mold for manufacturing a light guide plate.
In this method, a concave / convex pattern is previously formed on a mold by machining, chemical etching, electric discharge machining, or the like, and then injection molding is performed using the mold to form a light guide plate having a concave / convex surface. I was

[0003] In a light guide plate, various optical performances such as luminance and uniformity of a light exit surface are lifelines, and they are delicately changed depending on the size and shape of the light guide plate and other various conditions. Therefore, when the specifications required for the light guide plate are changed, it is necessary to reassemble the concavo-convex pattern each time and perform a preliminary evaluation to confirm the performance. Therefore, a prototype light guide plate formed by injection molding or the like using a prototype die is subjected to a performance test each time to test whether it satisfies the specified performance.

The biggest problem in the manufacture of the light guide plate utilizing such a mold is that a light guide plate having the performance required at one time is very rarely obtained. , Often end up with the final product. During this time, expensive molds must be re-manufactured many times, which inevitably causes a cost increase. In addition, in the case of small-lot production of many kinds, this method has a problem that the ratio of the preliminary confirmation test is relatively high, so that the cost becomes more expensive and it is difficult to cope.

[0005] This point is the same even when a white printed dot pattern is formed on the reflecting surface of the resin plate to form a light guide plate. Using this prototype printing screen, dot printing was performed on a resin plate to produce a large number of prototype light guide plates, which were carefully checked before starting mass production. Therefore, regardless of the method of manufacturing the light guide plate, mass production of the light guide plate requires a lot of man-hours and money and a long development time in such a prototype stage. Reduction was an urgent issue.

[0006]

SUMMARY OF THE INVENTION A first object of the present invention is to solve the above-mentioned conventional problems and to produce a prototype light guide plate for pre-evaluation confirmation in a simple, inexpensive and short time. If you can confirm, you can start mass production immediately,
At the same time, there is a development of a method for manufacturing a light guide plate that can quickly respond to high-mix low-volume production. The second problem is to make it possible to easily manufacture a light guide plate mold using the light guide plate. It is in.

[0007]

A light guide plate (A) according to claim 1
The manufacturing method of “is to irradiate the laser beam (5) directly to the resin plate (8) to process a light scattering pattern comprising a large number of recesses (9) on at least one surface (8a) of the resin plate (8). "
It is characterized by things.

Claims 2 and 3 relate to the shape of the light-scattering pattern, which is characterized in that the light-scattering pattern is composed of many dots or many concave stripes.

Instead of performing white dot printing on a resin plate by a conventional silk screen printing method, or using a mold having irregularities on the surface to form a light guide plate having irregular dots on the surface, extrusion molding is used. The surface of a resin plate (8) produced by casting polymerization or injection molding is directly irradiated with a laser beam to form a large number of dot-shaped or concave-shaped concave portions (9) to form a light scattering pattern. Light plate (A).

The dot-shaped or concave-shaped concave portion (9) can be formed into a free shape by a method of irradiating a laser beam (5). Generally, the shape of the bottom portion is spherical or concave. The depth depends on the irradiation conditions.

A light source (10) is arranged at the edge of the light guide plate (A) formed as described above, and the incident light from this light source (10) is converted into a dot-shaped or concave-shaped concave portion in the light guide plate (A). The light is diffused by (9) and emitted from the light emitting surface. Since the light diffusion pattern composed of the concave portion (9) is directly engraved on the resin plate (8) by the laser beam (5), the concave portion (9) is controlled only by controlling the output of the laser beam (5) or the pattern. The light diffusion pattern consisting of can be freely and finely changed, and in the case of trial production, of course, once the trial production is completed, it is possible to shift to laser processing under that condition, and it can be adapted to some mass production . Of course, even in the case of high-mix low-volume production, prototypes can be made easily and inexpensively, so that it is possible to respond quickly.

A fourth aspect of the present invention relates to a method for manufacturing a light guide plate molding die (15), wherein the light guide plate (A) according to any one of the first to third aspects is used as a matrix, and the light scattering pattern forming surface is plated. After the formation of the plating layer (13), the plating layer (13) is removed from the light guide plate (A) to form a precision inversion mold (15). "

According to this, the mold (15) can be made directly by using the prototype light guide plate (A) which has been confirmed to satisfy the specification conditions. Production of light plate molds becomes possible, and the cost of producing light guide plates can be greatly reduced.

[0014]

FIG. 1 is a schematic view showing the steps of the processing method of the present invention. (1) is the CRT, (2) is the main body of the personal computer, which stores the CAD software for figure creation, and the necessary conditions such as the light scattering pattern and the shape and depth of the recess (9) necessary for the light guide plate creation Is created and stored.

[0015] (3) is a laser beam irradiation device, which is connected to the personal computer (2). The laser beam (5) is emitted according to the control condition by a command from the personal computer (2), and the scan mirror (6). In general, the light is condensed by the condensing lens (4) on the surface of the resin plate (8) such that the condensed spot is minimized. This resin plate (8) is set on the XY precision moving table (7) and connected to the personal computer (2) in the same manner as the laser beam irradiation device (3). Move exactly to.

The above-mentioned laser beam (5) is scanned by the scan mirror (6) and the laser beam irradiation device (3) is turned on and off, whereby the resin on the surface (8a) of the resin plate (8) evaporates instantaneously. A recess (9) is formed. The shape of the concave portion (9) in the plane direction is free, and the depth thereof is free depending on the laser beam irradiation intensity and time. These light scattering patterns (the number and arrangement of the depressions) and their shapes, depths and sizes can be freely set by inputting data.

The laser beam (5) is moved by the scan mirror (6) and the XY precision moving table (7) and intermittently illuminated by turning on and off the laser beam (5). The dot pattern as input is processed in the whole of (8a). If the moving speed of the XY precision moving table (7) is constant and the on / off interval of the laser beam (5) is short (long), the dot interval is narrowed (expanded), and vice versa. Furthermore, if the ON / OFF interval of the laser beam (5) is constant and the moving speed of the XY precision moving table (7) becomes faster (slower), the dot interval becomes narrower (expands). When the XY precision moving table (7) is moved while the laser beam (5) is emitted, free grooves can be carved, starting with concave streaks.

FIG. 2A is a schematic view of the dot processing on the resin plate (8) by the laser beam (5) as viewed from the front direction.
FIG. 2 (b) is an enlarged cross section of the processed dot-shaped concave portion (9). The condensing point on the surface (8a) of the resin plate (8) is instantaneously evaporated by the condensed laser beam (5) as described above, and a hemispherical concave portion (9) is formed. Of course, if the irradiation time is lengthened, a concave portion (9) will be formed in which the opening does not expand so much but the depth increases with the irradiation time. By moving the laser beam (5) back and forth and left and right, concave portions (9) of various shapes are formed in accordance with the movement pattern.

FIG. 3 shows an example of a dot pattern drawn on the surface (8a) of the light guide plate (A). Light from the light source (10) disposed on the end face of the light guide plate (A) is The light is repeatedly emitted from the surface by the concave portion (9) formed on the front surface or the rear surface or both surfaces of (A), but the depth and the projected area are increased as the distance from the light source (10) increases. The concave portion (9) is designed so that the scattering ratio of the diffused light in the light guide plate (A) increases, and the light output from the surface becomes uniform.

In the case of FIG. 3, the dot-shaped concave portions (9) having the same diameter increase in number and density as the distance from the light source (10) increases, so that the projected area increases.
Of course, the present invention is not limited to this, and it may be formed such that its diameter increases as the distance from the light source (10) increases and its projection area increases, or the depth of the concave portion (9) gradually increases and the degree of scattering increases. The light guide plate (A) is designed so that the brightness and the uniformity over the entire light exit surface of the light guide plate (A) are substantially uniform. Further, the concave portion (9) is not limited to a dot shape, and may be a linear shape or any other shape.

This light scattering pattern is shown in the front of the resin plate (8).
It is processed on at least one of the back surfaces. When processing is performed on one surface, generally, the processed surface is a reflection surface, and the non-processed surface is a light output surface (of course, the processed surface may be a light output surface). Then, the surface brightness is improved by arranging such that the depth of the uneven pattern increases and the projection area in the direction perpendicular to the light source incidence direction increases as the distance from the light source (10) arranged at least on one end surface increases. Uniformity can be achieved.

In this manner, the light guide plate (A) for the trial operation is manufactured, and is subjected to a performance test to determine whether or not the light guide plate is acceptable. That is, as described above, the light source (1) is formed on the incident end face of the light guide plate (A) formed by directly forming the concave portion (9) with the laser beam (5).
0) is placed, and when this is lit, the placed light source (1
The light from 0) is reflected on the concave (9)
Are scattered by the dot pattern.

Among the light incident on the light guide plate (A), the light transmitted through the back surface is a light reflecting member (12) stretched along the back surface.
The light is re-entered into the light guide plate (A), and is uniformly diffused throughout the light guide plate (A) by the dents (dot patterns). The light is emitted over the entire surface. If the emitted light has substantially uniform brightness over the entire surface of the light emission surface and the uniformity thereof is substantially constant, the light passes.

If the test passes, the process shifts to a mass production process using laser light, and the resin plate (8) is laser-processed under the same conditions. Alternatively, it is used as a matrix of a light guide plate forming die (15) using inverted precision plating as described below. Conversely, if the test is failed, operate the personal computer (2) to change the output conditions, change the light diffusion pattern, engrave the resin plate (8) with laser light, and use the next prototype light guide plate. Create (A).

According to the method of manufacturing a light guide plate (A) by directly engraving a laser beam as in the present invention, it is possible to easily change the trial production conditions simply by inputting the conditions to the personal computer (2). In addition, it is extremely easy to produce a prototype under the changed conditions because the concave portion (9) is directly formed on the resin plate (8). Equipment costs such as mold production, injection molding and casting polymerization) are not required, and development costs and mass production lead time can be drastically reduced, and data of development patterns can be directly input to mass production equipment for use. Mass production launch is fast,
High reproducibility of development performance.

FIG. 4 is a structural view of an embodiment of the surface light emitting device incorporating the light guide plate (A) formed as described above. Light introduced into the light guide plate (A) from one end of the light guide plate (A) from the light source (10) is repeatedly diffused in the light guide plate (A), and a part of the light is disposed along the reflection surface which is the back surface. (12)
Then, the light is again incident on the light guide plate (A), and finally all light is emitted from the light exit surface of the light guide plate (A).

FIG. 5 shows an example of the light diffusion. The incident light from the end surface (8b) of the light guide plate (A) collides with the concave portion (9) formed on the reflection surface side of the light guide plate (A), and a part thereof is reflected, and the remaining portion enters the concave portion (9). It is transmitted and diffused in all directions. The light traveling in the light guide plate (A) is
Each time it collides with the concave portion (9), transmission and reflection in the light guide plate (A) are repeated, and finally the light is guided upward as described above.
Light is emitted from the light emitting surface, which is the surface of the light guide plate (A).

In the above case, light scattering and light emission by the dot-shaped concave portions (9) have been described. However, the same applies when the light diffusion pattern is a concave stripe. The concave stripes may be parallel lines or cross lines crossing each other. In any case, as described above, as the distance from the light source (10) increases, the projection density increases, the degree of scattering increases, and the optical conditions such as the luminance and uniformity of the light exit surface of the light guide plate (A) become substantially uniform. Designed to.

FIG. 6 shows a procedure for manufacturing a plating layer mounting type (14) for a light guide plate using the prototype light guide plate (A) formed by the method of the present invention. The light guide plate (A), which has been subjected to the dot pattern processing by laser light irradiation and has passed the performance test, is used as a master, and the surface (8a) is subjected to electroless plating or silver vapor deposition to obtain the surface (8a). Is made conductive, and then a thick plating of Ni, Cr, etc. is performed, and the plating layer (13) is reverse-adhered to the surface (14a) of the plating layer mounting die (14) to form a light guide plate molding die ( Make 15). When resin molding is performed using the light guide plate molding die (15), a dot pattern approved product can be mass-produced as it is.

(Embodiment) Using the laser irradiation apparatus shown in FIG. 1, a dot pattern was input and a dot-shaped concave portion was formed on the back surface of a 6-inch light guide resin plate (3 × 9 × 12 mm PMMA resin). The recess had a diameter of about 0.3 mm, a depth of about 0.03 mm, and a pitch of about 1 mm. When the brightness of the white dot pattern printed product formed under the same conditions was compared, the white dot printed product was 2200 cd / m2, whereas the laser beam processed product was 2400 cd / m2. . Therefore, in the product according to the method of the present invention, luminance equal to or higher than that of white dot printing was obtained.

Next, a comparison with the dot pattern forming method using laser light according to the present invention according to the present invention will be described below. Process name Printing method In-mold transfer processing Laser processing method of the present invention 1 Pattern study Pattern study Pattern study 2 Film creation Film creation Laser trial fabrication 3 Screen fabrication Mold fabrication Measurement / evaluation 4 Ink arrangement Mold etching 5 Prototype printing Cell cast prototype (Molding) 6 Measurement / Evaluation Measurement / Evaluation 7 Mold inserter 8 Injection trial production 9 Measurement / Evaluation Comparing the development process by processing method Method)> White dot printing method> In-mold transfer method using a mold.

The lower the development cost, the better the cost is. Laser (method of the present invention)> white dot printing method> in-mold transfer using a mold, and the method of the present invention is applicable to any method. It turns out to be an advantage.

Next, a comparison of the mass production start-up process of the light guide plate will be described below. Type White dot printing processing (comparative example) Laser processing (method of the present invention) 1 Development screen set Development pattern / data input 2 Jig set Jig set 3 Ink preparation Mass production 4 Test printing 5 Measurement / evaluation 6 Mass production White dot printing processing In the case, the first lot is 3
It is necessary to adjust about once, but in the case of the laser processing method of the present invention, since the development data is used as it is as mass production data, the reproducibility is high, and it is possible to directly enter the mass production process,
Very simple.

Next, an example of the production capacity of the laser processing method will be described below. When 0.3mm diameter dots are processed at 1mm pitch (100 pieces / cm2), the production capacity of light guide plate by size is 5 inches, 35,000 pieces per month, 8000 pieces for 12 inches, and 4100 pieces for 17 inches. Yes, a light guide plate of about 5 inches can be produced on a regular basis, producing about 35,000 sheets per month, which is equivalent to current white dot printing.

A light guide plate of about 10 inches can be produced at 10,000 per month.
The number of sheets is not suitable for mass production models, but the running cost is very low, so production with a plurality of facilities is possible, and mass production is possible depending on the facilities. In addition, the method of the present invention is advantageous for the production of very small lots because the setup change time is short. In addition, the processing method of the present invention can cope with any size of the light guide plate with the same equipment, and has an advantage of high production flexibility.

[0036]

According to the light guide plate processing method of the present invention, the light scattering pattern of dots or concave stripes is directly engraved on the light guide plate by the laser beam irradiation device, so that indirect development equipment and materials are unnecessary and development costs are reduced. The time required for mass production can be greatly reduced. Also, using the light guide plate molded by this method as a matrix,
If molding dies are manufactured using plating technology, mass-produced dies can be easily made, and this is very effective in terms of mold production.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a schematic embodiment of a laser irradiation apparatus that performs a method of the present invention.

2A is a schematic front view of dot processing on the light guide plate by the processing method of FIG. 1, and FIG. 2B is an enlarged cross-sectional view of a processed portion.

FIG. 3 is a back view of the light guide plate showing an example of a dot pattern formed by the method of the present invention.

FIG. 4 is a side view showing a configuration example of a surface light emitting device incorporating the light guide plate of the present invention.

FIG. 5 is a partially enlarged sectional view showing a part of light diffusion in the light guide plate of the present invention.

FIGS. 6 (a) to 6 (c) are procedures for producing a light guide plate forming die with a concave dot pattern on the surface by precision plating inversion using the light guide plate formed by the method of the present invention as a matrix. Showing process chart

[Explanation of symbols]

 (1) CRT (2) Personal computer (3) Laser irradiation device (4) Condensing lens (5) Laser light (6) Scan mirror (7) XY precision moving table (8) Resin Plate (8a) ... Light guide surface (8b) ... Light guide plate end surface (9) ... Depressed portion (10) ... Light source (11) ... Diffusion plate (12) ... Reflection plate (13) ... Plating layer (14) ... For light guide plate Plated layer mounting type (15): Mold for forming light guide plate

Claims (4)

[Claims] 1. A method for manufacturing a light guide plate, comprising: irradiating a laser beam directly onto a resin plate to form a light scattering pattern comprising a large number of recesses on at least one surface of the resin plate. 2. The method for manufacturing a light guide plate according to claim 1, wherein the recess is a dot. 3. The method for manufacturing a light guide plate according to claim 1, wherein the concave portion is a concave stripe. 4. A light guide plate according to claim 1, wherein the light guide plate according to claim 1 is used as a matrix, a surface on which the concave portion is formed is plated, and after the plating layer is formed, the plating layer is removed from the light guide plate to form a precision inversion mold. A method for manufacturing a light guide plate mold.