JP2006168260A - Manufacturing method of mold for molding light guide plate, mold for molding light guide plate, and light guide plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold for molding light guide plates which produces a large amount of high performance light guide plates inexpensively, stably and in a short time, and to provide its manufacturing method. <P>SOLUTION: A work piece 2, which is the mold for molding light guide plates, is processed by using a laser beam 60 controlled by a galvanoscanner and a long focal f-Θ lens 40 into such a shape as to form a light guide plate high in light scattering effect. The processed pattern is, for example, a ring formed by pulse marks, one wherein the inside of a ring is hatched, a recessed groove or the like. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light guide plate molding die.

The light guide plate is a member that guides light to a non-self-luminous body typified by a liquid crystal display.
As an example of a conventional light guide plate, a light guide plate 900 is shown in FIG. On the surface of the light guide plate 900, a pattern 900a for guiding light to the liquid crystal cell by reflection or scattering is formed.
As one method of forming such a light guide plate, there is a method of creating a patterned mold and transferring the pattern onto the surface of the light guide plate. As a conventional method for manufacturing a light guide plate molding die, processing of a reflection / diffusion surface by machining, processing by a lithography process, and the like are common.

  However, these processing methods require several tens of hours to several days. This also makes it very expensive. The pattern arrangement of the light guide plate, that is, the optical design has not been completely established yet, and trial and error is the current situation, so in the lighting device field where development speed is required recently, shortening the production time is a major issue. Yes.

In order to solve such a problem, the following methods have been adopted as a method of forming the light guide plate.
Patent documents 1 and 2 are approaches by laser processing, and disclose a method in which a resin is directly laser processed to create a light guide plate.
Patent Documents 3 to 5 disclose a method in which an ultrashort pulse laser is used for a plastic resin, fine processing is performed, and a mold is formed by an electroforming technique using this as a prototype.
Patent Document 6 discloses a method of processing a molding die by sandblasting.
Patent Documents 7 and 8 disclose a method of processing a molding die using a laser as one of processing tools.

JP 2002-103379 A JP 2000-66029 A JP 2003-334817 A JP 2004-117434 A JP 2004-117433 A JP 2001-328070 A JP 11-339527 A JP-A-8-327807

However, the above-described method cannot stably mass-produce a high-performance light guide plate at a low cost and in a short time.
Although the methods of Patent Documents 1 and 2 are effective for producing a prototype model, they are not mass-productive and have low optical characteristics as compared with a molded product using a mold. Further, since this processing is generally performed with a CO2 laser, it is unsuitable for processing into a metal mold material, fine processing cannot be expected, and a high-performance light guide plate cannot be manufactured.
Since the methods of Patent Documents 3 to 5 use a short pulse laser that uses a multiphoton absorption reaction, the processing time is longer than when a laser that uses thermal processing is used. Moreover, the short pulse laser is a developing technology and its structure is complicated, so the apparatus is expensive and the industrial property is poor. It cannot be differentiated from conventional lithography.
The method of Patent Document 6 has poor reproducibility, and at present, mass production quality cannot be maintained in multi-piece molding.
In the methods of Patent Documents 7 and 8, there is a processing on a molding die, but a laser is only described as one of processing tools, and details of the processing method are not described. For this reason, it is unclear what the details of laser processing that produce advantageous effects in terms of performance improvement and the like are.

  The present invention has been made to solve the above-described problems, and provides a method for manufacturing a light guide plate molding die for mass-producing a high performance light guide plate in a short time at a low cost. The purpose is to do.

  In order to solve the above-described problems, a method for manufacturing a light guide plate molding die according to the present invention is a method for manufacturing a light guide plate molding die that is transferred to a resin and molds a light guide plate. The energy beam is converged and processed on at least one surface to form dots having a predetermined shape.

The dots may be characterized by comprising an outer periphery and a plurality of parallel straight lines formed inside the outer periphery.
The dots may be characterized by comprising an outer periphery and a free curve formed inside the outer periphery.
The dots may be arranged in any shape of a parabola, a sine wave, a straight line, and a free curve.
The dots may be any one of a plurality of concentric circles, ellipses, and polygons.
The dots may be formed by repeatedly irradiating energy rays at the same position of the mold.
The order in which the dots are formed may be an order in which adjacent dots are successively formed.

  The light guide plate molding die manufacturing method according to the present invention is a light guide plate molding die manufacturing method in which a light guide plate is molded by being transferred to a resin, and energy is applied to at least one surface of the mold. The wire is converged and heated to form a concave groove.

The concave groove may be any one of a parabola, a sine wave, a straight line, and a free curve.
The focal point of the energy beam may be displaced in the depth direction of the mold, and the bottom of the concave groove may have a free curve shape in a cross section along the bottom of the concave groove of the mold.
The energy beam is an energy beam generated by pulse oscillation, and the dot or concave groove is constituted by a plurality of pulse marks, and the byte size of the plurality of pulse marks may be 10 μm or less.
The energy beam is an energy beam generated by pulse oscillation, and the depth of the dot or the concave groove may be 1 μm to 30 μm.
Around the dot or the concave groove, a raised portion may be formed on the surface of the mold that is higher than the portion not subjected to the energy beam processing.
The dot or the concave groove may include a spark portion.
The vicinity of the position where the energy rays converge may be cooled with gas or liquid.
The vicinity of the position where the energy rays converge may be in a shield gas atmosphere.
The vicinity of the position where the energy rays converge may be in the assist gas atmosphere.
Before forming the dot or concave groove, a texture pattern may be provided on the surface of the mold.
The energy beam may be a laser.
The energy beam may be any one of a heat generation region wavelength laser, a non-thermal processing region wavelength laser, an ultrashort pulse laser, an X-ray, and an electron beam.
Different light guide plate forming molds may be obtained by performing electroforming on the manufactured light guide plate forming molds and inverting the concavities and convexities.

The light guide plate forming mold according to the present invention is manufactured using any one of the above-described light guide plate forming mold manufacturing methods.
The light guide plate according to the present invention is manufactured using the above light guide plate forming mold.

  The light guide plate molding die according to the present invention utilizes the precision and fine processability of laser, and the diffused reflection part is formed by irradiating the laser on both sides or one side of the light guide plate molding die and processing. Is done. A high-intensity light guide plate is manufactured by accurately and faithfully transferring the light diffusion portion of the processed mold to a plastic resin.

  According to this invention, the light guide plate molding die is processed by focusing the laser on the surface of the die to form dots having a predetermined shape. Mass production in a short time.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1 FIG.
The first embodiment utilizes a processing phenomenon at the time of thermal processing with a pulsed laser. In the first embodiment, a laser marker is used. The laser marker uses a so-called galvano scanner optical system that scans a beam with two mirrors.
FIG. 1 shows a mold manufacturing apparatus 200 and a work 2 that is a mold according to Embodiment 1 of the present invention. The mold manufacturing apparatus 200 includes a laser transmitter 10, an expander 70 that expands the beam diameter of the laser, an X-axis mirror 21 and a Y-axis mirror 22 that control a processing position by changing a reflection angle of the beam, and a beam. It has a bender mirror 30 that is incident on the condensing lens, and a condensing lens 40 that is a long focal f-Θ lens that converges the incident beam to a target processing position.

The laser transmitter 10 transmits a laser beam 60 for shaping the surface of the workpiece 2. The laser transmitter 10 includes a shutter (not shown), and can turn on / off the laser beam 60 appropriately.
The laser beam 60 is generated by a pulse laser, for example, a YAG laser having a wavelength in the near infrared region. The expander 70 widens the beam diameter of the laser beam 60.

The X-axis mirror 21 and the Y-axis mirror 22 are large enough to receive the laser beam 60 with the expanded beam diameter, and reflect the laser beam 60 at a controlled angle, respectively. Make it incident. In addition, in order to perform high-precision operation while holding the relatively large X-axis mirror 21 and Y-axis mirror 22 in this way, the mechanical rigidity of the entire mold manufacturing apparatus is configured to be high.
In general, high-speed operation of a large mirror is difficult, but the processing speed in the first embodiment is in the range of several mm / s to several hundred mm / s, which is a relatively low speed range. It is.

  The bender mirror 30 further reflects the laser beam 60 so as to enter the condenser lens 40. At this time, the laser beam 60a or the laser beam 60b is incident on the condenser lens 40 at different angles depending on the angles of the X-axis mirror 21 and the Y-axis mirror 22 described above.

  The condensing lens 40 cancels out the difference in incident angles generated in the laser beams 60a and 60b, and always makes the laser beams 60a and 60b incident on the surface of the workpiece 2 at substantially the same angle. The condensing lens 40 converges the laser beams 60a and 60b at an arbitrary fixed depth near the surface of the workpiece 2, that is, a distance from the surface. Since the condensing lens 40 is a long focal f-Θ lens, a wide working area is secured.

As described above, the mold manufacturing apparatus 200 and the workpiece 2 can converge the laser beam 60 at one point on the surface of the workpiece 2 or on a plane that is a certain distance from the surface. The position of the point where the laser beam converges changes according to the angles of the X-axis mirror 21 and the Y-axis mirror 22.
The workpiece 2 is held by a jig or the like. The surface of the work 2 has a mirror surface with a roughness of Ra = 0.25 μm. This mirror surface is heated by the laser beam 60 converged to one point, and forms a rough portion 2a or 2b peculiar to thermal processing. In the same manner, a pattern 2x composed of a large number of rough portions is formed. In this way, the surface of the workpiece 2 is processed and molded.

As shown in FIG. 2A, each rough portion is a dot 101 which is a pulse mark ring in which a plurality of pulse marks 101a partially overlapping each other are arranged in an annular shape. Each pulse mark 101a is formed by one pulse irradiation, and the focal point of the laser forming this pulse mark 101a is set at a constant scanning speed in the circumferential direction of a circle having a specific diameter, for example, in the direction of arrow c. By moving it, the dot 101 is formed. At this time, the scanning speed multiplied by the pulse period, that is, the distance that the laser focus moves between two successive pulse oscillations is called the byte size. By controlling the bite size to be 10 μm or less, it is possible to form a processing mark having excellent optical characteristics.
In this example, the pulse period is relatively long and each pulse mark 101a is large, and the stripe pattern of the pulse mark 101a is clearly expressed.
The dot 101 uses a thermal processing phenomenon peculiar to a pulse laser, intentionally expresses a pulse mark on the dot itself, is processed as having a certain processing depth, and obtains a light diffusion effect associated therewith.

FIG. 2B is a cross-sectional view of the dot 101 in FIG. Due to the thermal processing phenomenon peculiar to the pulse laser, the periphery of the pulse mark 101a swells with heat and remains as a burr 101c. The burr 101c is raised from the surface of the workpiece 2 that is not processed. The pulse marks 101a and burrs 101c form dots 101.
The depth of the pulse mark 101a is, for example, 1 μm to 30 μm.
By using the burr 101c as it is, a convex portion corresponding to the pulse mark 101a and a groove corresponding to the burr 101c around it are formed on the light guide plate formed using the workpiece 2 as a mold. Thus, a light diffusion effect can be obtained.
As described above, in the method for manufacturing a light guide plate molding die according to the present invention, a portion that rises more than a portion that is not laser-processed on the surface of the die is formed around the dot or the concave groove. Increase the light diffusion effect.

FIG. 3 shows an example of the formed pattern 2x and its formation order.
The processing by the laser beam 60 on the surface of the workpiece 2 generally proceeds along the first direction, that is, the direction of the arrow a, and finely along the second direction, that is, the directions of the arrows b1 and b2 orthogonal to the first direction. And proceed.
First, the dot 101 of FIG. 2A is formed in the lower right portion of the work 2 in FIG. This is the dot 2c in FIG. From there, the same dot row is formed in the direction of the arrow b1 from the dot 2d. Next, a dot 2e is formed, and a dot row is formed in the direction of arrow b2 from there to dot 2g. Further, a dot 2g is formed, and thereafter the dot formation continues in the same manner, and finally a pattern 2x is formed.
Thus, the uniformity of the shape of the spark portion can be improved by sequentially performing laser irradiation on adjacent dots, that is, by successively forming adjacent dots. The spark part is a minute convex rough surface (not shown) on the mold surface that is present around the processed part, and when this is transferred to the resin, it has a fine concave shape.
Processing pattern data, for example, information such as the pattern origin position is created and stored using, for example, CAD.
Thus, in the method for manufacturing a light guide plate molding die according to the present invention, the order in which dots are formed is the order in which dots adjacent to each other are successively formed. The degree of uniformity can be increased.

After the molding of the surface of the workpiece 2 is completed in this way, the workpiece 2 on which the pattern 2x is formed is transferred to a resin (not shown), thereby molding the light guide plate. At this time, in the light guide plate, the portion where the rough portion included in the pattern 2x of the workpiece 2 is transferred is a portion having a large light diffusion effect because it is a transfer of the rough portion peculiar to thermal processing.
As described above, in the method for manufacturing a light guide plate molding die according to the present invention, the laser is converged and processed on at least one surface of the die to form dots having a predetermined shape. A mold for a large light guide plate is manufactured.

  As described above, according to the first embodiment of the present invention, the light guide plate is formed by transferring the mold, so that the same pattern can be stably and rapidly produced.

Compared with a conventional method, that is, a manufacturing method using machining or lithography, the molding die production time is greatly reduced, and the molding trial cycle is quick. Specifically, since pattern processing is completed in several minutes to several tens of minutes, optical evaluation can be performed several times a day. Thus, the speed of light guide plate evaluation speed in the cut-and-try method is unparalleled.
In the current situation where it is difficult to obtain a light guide plate with desired optical characteristics in a single trial, the light guide plate mold manufacturing method using laser processing allows optical adjustments such as trial and error and fine adjustment in a short time. Superiority is high.

In addition, the efficiency of fine adjustment is improved and high quality can be realized. Moreover, short delivery time and low cost can be realized, and the cost can be reduced.
Since a YAG laser suitable for processing a metal material is used for processing, fine processing is possible and a high-performance light guide plate can be formed. In addition, since a pulse laser is used, the processing time is shortened and the laser transmitter is configured at a low cost.
Further, since the pattern 2x is transferred by the workpiece 2, the reproducibility is high and the quality can be maintained in mass production.
In addition, since the laser processing pattern 2x is specifically provided, the above effects can be clearly obtained.

In the first embodiment described above, the following modifications can be made.
In the first embodiment, the surface processing of the workpiece 2 is performed only on one side, but this may be performed on both surfaces of the workpiece 2.

The state of the dot 101 can be controlled by changing the irradiation state of the laser beam 60.
Since the byte size, that is, the interval between the pulse marks 101a is controlled as a product of the scan speed and the pulse period, the optimum pulse mark generation condition can be obtained from the relationship between the pulse period and the scan speed. Therefore, it is possible to easily form a processing trace shape having excellent optical characteristics. In FIG. 2A, the stripe pattern of the pulse mark 101a is clearly expressed, but this stripe pattern can be adjusted by the byte size. For example, the pulse period is shortened to form the dots 102 shown in FIG. May be. In the dot 102 of FIG. 4A, since the byte size is small, there is no clear pulse mark, and the surface of the irradiation mark 102a is smooth. In addition, a burn due to thermal influence, that is, a spark portion 102b is formed around the irradiation mark 102a. This spark portion 102b is a minute convex rough surface, and when it is transferred to the resin, it becomes a fine concave shape, so that the diffusion area increases and has a role of correcting the dot diffusion effect.

FIG. 4B is a cross-sectional view of the dot 102 in FIG. Similar to the dot 101 in FIG. 2B, the periphery of the irradiation mark 102a rises with heat and remains as a burr 102c due to the thermal processing phenomenon peculiar to the pulse laser. The burr 102c is raised from the surface of the workpiece 2 that is not processed. The irradiation marks 102a and burrs 102c form dots 102.
By using the burr 102c as it is, a convex portion corresponding to the irradiation mark 102a and a groove corresponding to the burr 102c around the light guide plate formed using the workpiece 2 as a mold are formed. Thus, a light diffusion effect can be obtained.
The spark portion described above is formed by increasing the output of the laser beam 60 in addition to reducing the bite size.
As described above, in the method for manufacturing a light guide plate molding die according to the present invention, the dot or the concave groove includes the spark portion, so that the light diffusion effect of the light guide plate is increased.

The shape of the dot is not a simple circular ring like the dot 101 in FIG. 2A or the dot 102 in FIG. 4A, but the center of the laser focus moves along the pattern 103 shown in FIG. 5, for example. It may be formed by. The pattern 103 includes an outer periphery 103 a that is the same ring as that forming the dots 101, and equidistant parallel lines 103 b that hatch the inside. The outer periphery 103a does not have to be a ring as long as it surrounds a part of the surface of the workpiece 2.
The direction of the parallel line 103b may be a direction parallel to or perpendicular to a light beam from a light source handled by the light guide plate formed by the workpiece 2. In order to increase the optical characteristics as the light guide plate, a pattern perpendicular to the light source is particularly effective. The hatching interval is adjusted when creating machining pattern data by CAD depending on the width of the beam diameter.
Note that a pattern formed by a free curve may be used instead of the equidistant parallel lines 103b.

6 to 8 show the shapes of dots 104, 105, and 106, which are examples of dots formed by moving the laser focus along the outer periphery and the parallel lines inside the same as the locus 103 in FIG. Each is shown.
In FIG. 6A, the dot 104 includes an annular groove 104a and a parallel linear groove 104b. FIG. 6B is a cross-sectional view of the dot 104 of FIG. 6A taken along the line B-B. Like the dot 101 of FIG. 2B, an annular groove 104a and a parallel linear groove are shown. 104b, and a burr 104c formed by raising the periphery of each groove by heat.
The interval between the linear grooves 104b is relatively small, and a plane which is the unprocessed surface of the workpiece 2 does not remain between the adjacent linear grooves 104b.

In FIG. 7A, the dot 105 includes an annular groove 105a and a parallel linear groove 105b. FIG. 7B is a cross-sectional view of the dot 105 in FIG. 7A taken along the line C-C. Like the dot 101 in FIG. 2B, an annular groove 105a and parallel linear grooves are shown. 105b, and a burr 105c formed around each groove by heat.
The interval between the straight grooves 105b is larger than that of the dots 104 in FIG. 6, and there is a portion between the adjacent linear grooves 105b where a flat surface, which is the unprocessed surface of the workpiece 2, remains.

In FIG. 8A, the dot 106 includes an annular groove 106a and a parallel linear groove 106b. FIG. 8B is a cross-sectional view taken along the line DD of the dot 106 in FIG. 8A. Like the dot 101 in FIG. 2B, an annular groove 106a and a parallel linear groove are shown. 106b, and a burr 106c formed around each groove by heat.
The interval between the linear grooves 106b is larger than that of the dots 105 in FIG. 7, and there is a portion where a plane which is the surface of the workpiece 2 that is not processed remains between the adjacent linear grooves 106b.
By hatching the inside of the dots in this way, it is possible to form a pattern that increases the diffusion surface and realizes improvement in luminance.
Thus, in the method for manufacturing a light guide plate molding die according to the present invention, the dots are composed of the outer periphery and a plurality of parallel straight lines formed inside the outer periphery. improves.

The dot shape may be not only a circle but also a plurality of concentric circles, ellipses, quadrilaterals, triangles, and other polygons.
9A to 9D, some of the patterns having these shapes are partially shown. (A)-(d) shows the annular | circular shaped dot by Embodiment 1, a concentric dot, an elliptical dot, and a rhombus dot, respectively.
As described above, in the method for manufacturing a light guide plate molding die according to the present invention, since the dots have any one of a plurality of concentric circles, ellipses, and polygons, the light diffusion effect of the light guide plate is increased. .

Alternatively, the laser shutter is turned on and off at the same position, and this is repeated to repeatedly irradiate the same position of the work 2 with the laser, so that the spot size, that is, the size of the laser focus on the surface of the work 2 is about the same size. The light diffusing dots having a circular shape or a rough laser beam shape may be arranged. Note that the laser beam shape varies depending on the type of laser, and a single-mode laser is almost a perfect circle, but a multi-mode laser is distorted.
Thus, in the method for manufacturing a light guide plate molding die according to the present invention, the dots are formed by repeatedly irradiating the laser at the same position of the die, thereby increasing the light diffusion effect of the light guide plate.

The surface of the workpiece 2 may be preliminarily provided with a texture pattern by blasting to form a frosted glass, and then the dot pattern may be formed by laser processing as described above. Thereby, since the whole surface of the workpiece 2 is covered with the embossed pattern or the dots, the luminance uniformity is improved.
As described above, in the method for manufacturing a light guide plate molding die according to the present invention, since the embossed pattern is attached to the surface of the die before forming the dots or the concave grooves, the luminance uniformity of the light guide plate is increased. .

  The wavelength of the laser beam 60 may be in the infrared region or near infrared to ultraviolet region, and may be changed according to the absorption characteristics of the material of the workpiece 2 and the required processing accuracy. In particular, by using a wavelength close to ultraviolet light, processing including the element of quasi-light ablation becomes possible, and high-precision and fine processing is realized.

  Irradiation conditions such as the processing speed, output, and pulse period of the laser beam 60 may be changed as appropriate, thereby controlling the depth, shape, and line width of the laser-processed dots, that is, the light diffusion portion. . The light guide plate molding die is preferably processed to have a depth of 1 μm to 30 μm, particularly several μm to several tens of μm, from the required optical characteristics and moldability.

  After the light guide plate is injection-molded using the work 2 and the light guide plate is subjected to optical evaluation such as luminance distribution, optical fine adjustment may be performed based on the evaluation. That is, the brightness distribution is finely adjusted by performing additional machining with a laser while holding the workpiece 2 with a jig or the like and fixing the machining origin position. In this fine adjustment, the processing data is processed on the CAD data.

The processing pattern may be a pattern composed of dots or lines formed continuously instead of a pattern composed of dots spaced apart from each other as described above. FIGS. 10A to 10C show examples of patterns composed of lines. (A) is a linear pattern, (b) is a sinusoidal pattern, and (d) is a parabolic pattern. Further, the present invention is not limited to these pattern examples, and for example, a pattern based on a free curve may be used. Each line is a trajectory in which the center of the focal point of the laser moves, and irregular reflection grooves are formed by laser processing along the trajectory. This irregular reflection groove is a concave groove. By processing the mold surface in a linear manner in this way, the luminance is improved as compared with a pattern composed of spaced dots. The pattern composed of these dots or lines and the concave groove are formed by pulse marks of a pulse laser.
Thus, in the method for manufacturing a light guide plate molding die that is transferred to a resin and forms a light guide plate according to the present invention, a concave groove is formed by focusing a laser on at least one surface of the die. Therefore, the brightness of the light guide plate is improved.
Moreover, since the concave groove has any one of a parabola, a sine wave, a straight line, and a free curve, the luminance of the light guide plate is improved.
Further, since the laser is a pulse laser, and the dot or the concave groove is constituted by a pulse mark, the light diffusion effect of the light guide plate is increased.

  The depth of the concave groove is constant in the range of 1 μm to 30 μm, but this may not be constant, and a part or all of it may be outside the range of 1 μm to 30 μm. The depth of the groove may be controlled by displacing the focal point of the laser beam in the depth direction of the workpiece 2. For example, in the cross section of the workpiece 2 along the bottom of the groove, the bottom of the groove may have a free curve shape. By adopting such a shape, an ideal pattern can be processed by simulation, which is impossible with other processing methods.

The concave grooves may be continuous fine dots that are separated from each other and are formed by using a pulsed laser.
Thus, in the method for manufacturing a light guide plate molding die according to the present invention, since the dots are arranged in any one of a parabola, a sine wave, a straight line, and a free curve, the light diffusion effect of the light guide plate Increase

FIGS. 11 to 13 show the shapes of patterns 301, 302, and 303, which are examples of patterns formed by moving the laser focus along parallel lines, similarly to the locus shown in FIG. Show.
In FIG. 11A, the pattern 301 includes a plurality of parallel linear grooves 301a. FIG. 11B is a cross-sectional view taken along the line II of the pattern 301 in FIG. 11A, and parallel straight grooves 301a and burrs 301b formed around each groove by heat. Have
The interval between the linear grooves 301a is relatively small, and a plane which is the unprocessed surface of the workpiece 2 does not remain between the adjacent linear grooves 301a.

In FIG. 12A, the pattern 302 includes a plurality of parallel linear grooves 302a. 12B is a cross-sectional view taken along the line JJ of the pattern 302 in FIG. 12A, and includes parallel straight grooves 302a and burrs 302b formed around each groove by heat. Have
The interval between the linear grooves 302a is larger than that of the pattern 301 in FIG. 11, and there is a portion where a plane which is an unprocessed surface of the workpiece 2 remains between the adjacent linear grooves 302a.

In FIG. 13A, the pattern 303 includes a plurality of parallel linear grooves 303a. FIG. 13B is a cross-sectional view taken along the line KK of the pattern 303 in FIG. 13A, and parallel straight grooves 303a and burrs 303b formed around the grooves by heat. Have
The interval between the linear grooves 303a is larger than that of the pattern 302 in FIG. 12, and there is a portion where a plane which is a non-processed surface of the workpiece 2 remains between the adjacent linear grooves 303a.

  The light beam used for processing is not limited to a laser having a wavelength in the heat generation region, and may be a laser having a wavelength in the non-thermal processing region, or may be an ultrashort pulse laser. In addition, the light beam used for processing may be other than a laser as long as it is an energy beam, or may be an energy beam such as an X-ray or an electron beam. By using various energy rays, it is possible to select the optimum energy rays for the material to be processed and the processing shape.

  The workpiece 2 may be processed directly on a resin such as PMMA (polymethyl methacrylate) or PC (polycarbonate) instead of a molding die. In this case, it is necessary to select a wavelength having a large absorption characteristic with respect to the resin. Among lasers having a wavelength of 400 nm or less, a laser having a wavelength in the ultraviolet region that can reduce the beam size is particularly effective for fine processing. However, there is no particular limitation as long as it is a laser light source having a wavelength in which the transparent material has absorption characteristics.

  After finishing the work 2, the concave and convex portions may be inverted by a method such as electroforming to form a new light guide plate molding die. In this case, the surface of the obtained new mold has a convex pattern, and the light guide plate formed by this mold expresses a concave pattern. By doing so, the brightness of the light guide plate can be increased.

Embodiment 2. FIG.
In the second embodiment, the method of moving the laser focus on the workpiece in the first embodiment is not the method of moving the focus by the galvano scanner, but the method of moving the workpiece by the XY table.
FIG. 14 shows a mold manufacturing apparatus 201 according to the second embodiment and a work 2 that is a mold. The workpiece 2 is the same as that of the first embodiment.
The laser beam 60 expanded in diameter by the expander 70 is reflected by the bender mirror 30 and enters the condenser lens 41. The condensing lens 41 converges the laser beam 60 at one point on the surface of the workpiece 2 or on a plane at a certain distance from the surface. Unlike the first embodiment, the position of this focal point is fixed with respect to the condenser lens 41.

  The work 2 is fixed to the support surface of the movable table 80. The movable table 80 can be translated in three dimensions in the vertical and horizontal directions, and moves with the workpiece 2 to move the workpiece 2 relative to the laser focus. In this way, the laser focal point is relatively moved on the workpiece 2, and the same processing as in the first embodiment is performed.

In the second embodiment, the same modifications as those in the first embodiment can be applied, but the following modifications are also possible.
In order to suppress the transfer of heat to the non-processed mirror surface, that is, the surface of the workpiece 2 that is not laser processed, the processing site, that is, the vicinity of the focal point of the laser beam 60 may be cooled while being cooled with gas or liquid. FIG. 15 shows a usage state of the cooling device 91 that cools the processing site. Cooling gas or liquid is sprayed in the direction from the injection port 92 of the cooling device 91 toward the focal point of the laser beam 60, that is, in the direction of the arrow d, to cool the processing site.
Thus, in the method for manufacturing a light guide plate molding die according to the present invention, the vicinity of the position where the laser converges is cooled with gas or liquid, so that the processing accuracy of the light guide plate is improved.

In order to control the thermal effect of the laser, argon, nitrogen, helium gas, or the like may be used as a shielding gas, and processing may be performed in those atmospheres. FIG. 16 shows the state of use of the shield cover 94 that forms a shield gas atmosphere at the processing site. The shield cover 94 is a light collecting unit except for the gas inlet 94a and the gas outlet 94b formed around the processing site. The focal side of the lens 41 is almost covered.
The shield gas that flows in from the gas inlet 94a in the direction of the arrow e makes the vicinity of the outlet 94b, that is, the vicinity of the processing portion, in the shielding gas atmosphere, so that the processing portion is protected from oxygen in the air and oxidation is prevented.
Thus, in the manufacturing method of the light guide plate molding die according to the present invention, the vicinity of the position where the laser converges is in the shield gas atmosphere, so that the processing accuracy of the light guide plate is improved.

Further, oxygen gas or the like may be used as an assist gas instead of the shield gas. Since the vicinity of the processing site is in the assist gas atmosphere by the assist gas, thermal processing at the processing site is assisted and promoted.
Thus, in the manufacturing method of the light guide plate molding die according to the present invention, the vicinity of the position where the laser converges is in the assist gas atmosphere, so that the processing accuracy of the light guide plate is improved.

FIG. 17 is a diagram for explaining the action of the shielding gas and the assist gas described above.
(A1) is the shape of the processing mark 307 formed when processing is performed in a state where neither shield gas nor assist gas is used, and (b1) is a cross-sectional view taken along the line PP in (a1). In (a1) and (b1), the processing mark 307 has a groove 307a, a burr 307b formed by the surroundings being swelled by heat, and a spark portion 307c due to thermal influence.

(A2) is the shape of the processing mark 308 formed when processing using assist gas, (b2) is the QQ sectional view taken on the line (a2). In (a2) and (b2), the processing mark 308 includes a groove 308a, a burr 308b formed around the groove 308a by heat, and a spark portion 308c caused by heat.
Compared to the processing mark 307 when the assist gas is not used, the processing mark 308 when the assist gas is used promotes thermal processing, the burr 308b is larger, the groove 308a is deeper, and the spark portion 308c is wider. .

(A3) is a shape of a processing mark 309 formed when processing is performed using a shielding gas, and (b3) is a cross-sectional view taken along line RR of (a3). In (a3) and (b3), the processing mark 309 includes a groove 309a, a burr 309b formed around the groove 309a by heat, and a spark portion 309c due to thermal influence.
Compared with the processing mark 309 when the shield gas is not used, the processing mark 309 when the shield gas is used suppresses thermal processing, the burr 309b is smaller, the groove 309a is shallower, and the spark portion 309c is narrower. .

  In the first embodiment and the second embodiment described above, the movable parts may be combined. In other words, the X-axis mirror 21 and the Y-axis mirror 22, a condensing lens 40 that is a long focal f-Θ lens, and a movable table 80 are provided, and both the focal point of the laser beam 60 and the workpiece 2 can move. Such a configuration may be adopted.

  In the second embodiment, in addition to the effects obtained in the first embodiment, the movable range of the relative movement of the laser focus with respect to the workpiece 2 is not limited by the condensing lens. Can handle size.

It is a figure which shows the structure of the metal mold manufacturing apparatus 200 which concerns on Embodiment 1 of this invention. It is a figure which shows the shape of the dot 101 which concerns on Embodiment 1 of this invention. It is a figure which shows the pattern 2x of the dot which concerns on Embodiment 1 of this invention. It is a figure which shows the shape of the dot 102 which concerns on the modification of Embodiment 1 of this invention. It is a figure which shows the shape of the pattern 103 which concerns on the modification of Embodiment 1 of this invention. It is a figure which shows the shape of the dot 104 which concerns on the modification of Embodiment 1 of this invention. It is a figure which shows the shape of the dot 105 which concerns on the modification of Embodiment 1 of this invention. It is a figure which shows the shape of the dot 106 which concerns on the modification of Embodiment 1 of this invention. It is a figure which shows the shape of the dot which concerns on the modification of Embodiment 1 of this invention. It is a figure which shows the pattern which concerns on the modification of Embodiment 1 of this invention. It is a figure which shows the shape of the pattern 301 which concerns on the modification of Embodiment 1 of this invention. It is a figure which shows the shape of the pattern 302 which concerns on the modification of Embodiment 1 of this invention. It is a figure which shows the shape of the pattern 303 which concerns on the modification of Embodiment 1 of this invention. It is a figure which shows the structure of the metal mold manufacturing apparatus 201 which concerns on Embodiment 2 of this invention. It is a figure which shows the use condition of the cooling device 91 which concerns on the modification of Embodiment 2 of this invention. It is a figure which shows the use condition of the cover 94 which concerns on the modification of Embodiment 2 of this invention. It is a figure which shows the effect | action of shield gas and assist gas in the modification of Embodiment 2 of this invention. It is a figure which shows the shape of the conventional light-guide plate 900. FIG.

Explanation of symbols

2 Workpiece (light guide plate mold),
60, 60a, 60b Laser beam (energy beam),
2c-2g, 101, 102, 104, 105, 106 dots,
101a pulse marks,
102b, 307c, 308c, 309c spark part,
103a outer periphery, 103b parallel lines (parallel straight lines),
104a, 104b, 105a, 105b, 106a, 106b, 301a, 302a, 303a, 307a, 308a, 309a groove (concave groove),
101c, 102c, 104c, 105c, 106c, 301b, 302b, 303b, 307b, 308b, 309b Burrs (parts raised more than parts not subjected to energy beam processing).

Claims (23)

A method of manufacturing a light guide plate molding die that is transferred to a resin and forms a light guide plate,
A method for producing a light guide plate molding die, wherein energy dots are converged and processed to form dots having a predetermined shape on at least one surface of the die. The method for manufacturing a light guide plate molding die according to claim 1, wherein the dots include an outer periphery and a plurality of parallel straight lines formed inside the outer periphery. The method for manufacturing a light guide plate molding die according to claim 1, wherein the dots include an outer periphery and a free curve formed inside the outer periphery. The method for manufacturing a light guide plate molding die according to claim 1, wherein the dots are arranged in any shape of a parabola, a sine wave, a straight line, and a free curve. The method for manufacturing a light guide plate molding die according to claim 1, wherein the dots have any one of a plurality of concentric circles, ellipses, and polygons. The method of manufacturing a light guide plate molding die according to claim 1, wherein the dots are formed by repeatedly irradiating the energy beam at the same position of the die. The method for manufacturing a light guide plate molding die according to claim 1, wherein the dots are formed in an order in which adjacent dots are successively formed. A method of manufacturing a light guide plate molding die that is transferred to a resin and forms a light guide plate,
A method of manufacturing a light guide plate molding die, comprising: converging energy rays and heating to at least one surface of the die to form a concave groove. 9. The method of manufacturing a light guide plate molding die according to claim 8, wherein the concave groove has any one of a parabola, a sine wave, a straight line, and a free curve. The focus of the energy beam is displaced in the depth direction of the mold, and the bottom of the concave groove has a free curved shape in a cross section along the bottom of the concave groove of the mold. The manufacturing method of the metal mold | die for light-guide plate shaping | molding of Claim 8. The energy ray is an energy ray by pulse oscillation,
The dot or the concave groove is constituted by a plurality of pulse marks,
The method for manufacturing a light guide plate molding die according to claim 1 or 8, wherein the plurality of pulse marks have a byte size of 10 µm or less. The energy ray is an energy ray by pulse oscillation,
The method of manufacturing a light guide plate molding die according to claim 1 or 8, wherein a depth of the dot or the concave groove is 1 to 30 µm. 9. The light guide plate molding die according to claim 1, wherein a raised portion is formed around the dot or the concave groove with respect to the portion of the die that is not processed with the energy beam. Manufacturing method. The method of manufacturing a light guide plate molding die according to claim 1, wherein the dot or the concave groove includes a spark portion. The method for manufacturing a light guide plate molding die according to claim 1 or 8, wherein the vicinity of the position where the energy rays converge is cooled with a gas or a liquid. The method for manufacturing a light guide plate molding die according to claim 1 or 8, wherein the vicinity of the position where the energy rays converge is in a shielding gas atmosphere. The method for manufacturing a light guide plate molding die according to claim 1 or 8, wherein the vicinity of the position where the energy rays converge is in an assist gas atmosphere. 9. The method for manufacturing a light guide plate molding die according to claim 1 or 8, wherein a texture pattern is provided on a surface of the die before forming the dots or the concave grooves. 9. The method of manufacturing a light guide plate molding die according to claim 1 or 8, wherein the energy beam is a laser. 9. The light guide plate molding according to claim 1, wherein the energy beam is any one of a heat generation region wavelength laser, a non-thermal processing region wavelength laser, an ultrashort pulse laser, an X-ray, and an electron beam. Mold manufacturing method. 21. A light guide plate, wherein different light guide plate forming molds are obtained by performing electroforming on the light guide plate forming mold according to any one of claims 1 to 20 and inverting the unevenness. A method for manufacturing a molding die.   A light guide plate forming mold manufactured using the method for manufacturing a light guide plate forming mold according to any one of claims 1 to 21.   A light guide plate produced using the light guide plate molding die according to claim 22.

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