JP2006297945A - Optical panel die - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance productivity by reducing step numbers for die perfection and to achieve a sufficient flux distribution profile in a nearly perpendicular plane (grooved wall) of a molded optical panel. <P>SOLUTION: Following steps are performed in shaping, a diffusing surface forming die section 13 to form a diffusing surface 3 and a mirror surface forming die section 12 to form a mirror surface 2, in a die 11 for an optical panel. First, an outline figure of the diffusing surface forming die 13 to be shaped is made, on a first surface 13a for shaping the diffusing surface forming die section 13; and an outline figure of the mirror face forming die 12 to be shaped is made, on a second surface 12a for shaping the mirror surface forming die section 12. Thereafter the diffusing surface forming die section 13 is shaped by blast treating the first surface 13a, and then the mirror surface forming die section 12 is shaped by mirror finishing the second surface 12a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mold for an optical panel, and more particularly to a mold for an optical panel for molding an optical panel whose light direction can be controlled by a prism shape having a diffusing surface and a mirror surface.

  2. Description of the Related Art Conventionally, as an optical panel used for an overhead projector (hereinafter referred to as OHP), a prism array surface (a plurality of prism shapes) is provided on at least one surface, and at least one constituting a prism in one prism shape. A Fresnel lens having a function of controlling the light direction by making at least one surface a diffusing surface and at least one of the remaining surfaces as a mirror surface is known (see, for example, Patent Document 1). ).

  In this OHP 32, as shown in FIG. 39, the light from the light source 34 is condensed by a large-diameter Fresnel lens 30, and after passing through the transparent document 33, the condensed light path becomes an imaging lens 35, a reflection mirror. The condensing Fresnel lens 30 is substantially the same as one mirror surface 2 substantially inclined with respect to the panel surface 9 as shown in FIG. One vertical groove wall 31 forms one prism shape W, and a plurality of prism shapes W gather to form the prism array surface 4. By the way, as one drawback of the Fresnel lens 30 of the OHP 32, unnecessary light reflected or refracted from the groove wall 31 of the lens (light ray D in the direction D not facing the imaging lens 35) is very dazzling for the user of the OHP 32. It is to feel. Therefore, conventionally, the above-described drawbacks are solved by roughening the groove wall 31 shown in FIG.

  As a method of manufacturing a mold for molding the Fresnel lens 30, for example, in Japanese Patent Publication No. 61-16605, as shown in FIG. 41, a substantially vertical surface 13a to be finally left as a diffusion surface forming mold portion is provided. After the prism array-shaped surface 14 having the substantially inclined surface 12a to be finally left as the mirror surface forming mold portion is cut into a rough shape, the photoresist 40 is uniformly applied to the entire surface of the prism array-shaped surface 14. Then, the resist 40 is exposed and developed using the photomask 70 so that the resist 40 remains only on the substantially inclined surface 12a facing the lens center (FIG. 41B), and then the surface is centered on the lens center. The exposed substantially vertical surface 13a is roughened by etching to form the diffusion surface forming mold part 13, and then the remaining resist 40 is removed to provide the mirror surface forming mold part 1. Form, and in the press molding of the thermoplastic resin by the thus obtained mold 11 (FIG. 41 (d)), so that the production of the Fresnel lens 30 shown in FIG. 40.

However, in the conventional manufacturing method of the mold 11, after cutting into a schematic shape, in order to make the substantially vertical surface of the mold 11 a diffusion shape, a resist coating process, an exposure / development process, an etching process, Each resist removal step is necessary, and there are problems that the number of steps is large until the mold 11 is completed and the productivity is poor. In addition, since etching is applied to the rough surface processing, there is a problem that it is difficult to ensure the surface roughness for obtaining sufficient light distribution characteristics in the groove wall 31 of the optical panel 1 to be manufactured.
Japanese Examined Patent Publication No. 61-16605

  The present invention was invented in view of the above-described conventional problems, and it is an object of the present invention to provide a mold for an optical panel that can achieve a longer tool life and a longer tool life. To do.

  In order to solve the above-mentioned problems, in the invention according to claim 1, a diffusion surface forming mold part 13 for forming the diffusion surface 3 and a mirror surface forming mold part for forming the mirror surface 2. 12 is a mold for an optical panel for molding an optical panel whose light direction can be controlled by a prism shape having a prism shape, and a diffusion surface forming mold part 13 and a mirror surface forming mold part 12 by cutting. The material of the surface to be cut of the mold part block 10 in which is formed is made of copper plating.

  Such a configuration is preferable. In this case, it is possible to obtain a long-life mold 11 capable of extending the life of the cutting tool 6 and withstanding the molding life.

  In the invention described in claim 2, in claim 1, the surface roughness of the diffusion surface forming mold 13 is preferably Ra 0.66 or more and 1.5 or less. In this case, the optical panel A required value (for example, 60.2%) or more can be ensured as a light distribution ratio of 1.

  In addition, in order to prevent wear due to molding of the roughened diffusion surface forming mold part 13 and extend the life of the mold 11, the diffusion surface forming metal mold is provided in the invention of claim 3. It is preferable that the average aspect ratio of the surface shape of the mold part 13 is set to 0.61 or more so that a necessary light distribution ratio of the optical panel can be obtained.

  In the invention according to claim 4, in the rough surface shape of the diffusion surface forming mold part 13, an arbitrary upper limit value X and a lower limit with respect to the surface roughness center of the diffusion surface forming mold part 13. A value Y is set, and the range between them is set as a reference value range Z. Among the number of points in the surface roughness data profile, the number of points that fall within the reference value range Z and points that exceed the reference value range Z The ratio of the number of points exceeding the reference value range Z is preferably 8% or more.

  In the invention described in claim 5, it is preferable that the surface or surface layer of the diffusion surface forming mold part 13 is made of a material having wear resistance.

  In the invention described in claim 6, it is preferable to cover the surface of the diffusion surface forming mold part 13 with a protective coating having a thickness of 0.1 μm or more and 0.5 μm or less. The surface roughness of the diffusion surface forming mold part 13 can be ensured without filling the rough surface shape of the forming mold part 13 with a protective coating.

  In the invention described in claim 7, the protective coating is preferably Ni plating. In this case, the protective coating can be formed easily and uniformly.

  As described above, the mold for an optical panel according to the present invention is made of the material of the surface of the surface to be cut of the mold part block in which the diffusion surface forming mold part and the mirror surface forming mold part are formed by cutting. Since it is made of copper plating, it is possible to extend the life of the cutting tool and to obtain a long-life mold that can withstand the molding life.

  Hereinafter, the present invention will be described based on embodiments shown in the accompanying drawings.

  FIG. 1 shows an example of an optical panel mold 11 according to the present invention, and FIG. 2 shows an example of an optical panel 1 molded using the optical panel mold 11. It has a function of controlling the direction of light used in a panel for lighting equipment, etc., and has a prism array surface 4 composed of a plurality of prism shapes on at least one surface, and each prism shape has a prism At least one or more surfaces constituting the diffusing surface 3 are configured as a diffusing surface 3, and at least one of the remaining surfaces is configured as a mirror surface 2. Here, the pitch P of each prism shape is constituted by a minute prism array surface 4 having a thickness of about 0.05 mm to 5 mm, for example.

  FIG. 3 is an enlarged view of a part of the prism array-shaped surface 14 in FIG. 2, but one prism shape is composed of a plurality of surfaces and is substantially perpendicular to the panel surface 9. The surface to be a groove wall is a diffusing surface 3 (surface roughness Ra = 1.0 to 5.0, preferably Ra = 1.0 to 3.0). This surface is a mirror surface 2 (surface roughness Ra = 0.1 or less, preferably Ra = 0.05 or less). Thus, by defining the surface roughness state according to the surface direction of the prism, a preferable light direction control characteristic can be obtained.

  Here, as a reference example, as shown in FIG. 4, in the case where all the surfaces that are substantially vertical and substantially inclined with respect to the panel surface 9 are mirror surfaces 2, the optical panel 1. The light beam A incident from the prism array surface 4 side is refracted once on the substantially inclined surface of the prism, refracted when it exits after passing through the panel, and can direct the light in the target direction. The light beam B that has entered the position close to the substantially vertical plane is refracted once by the substantially inclined surface of the prism, then reflected by the substantially vertical plane, and emits light in the direction D opposite to the target direction. The optical panel 1 for controlling the light direction is inappropriate.

  As another reference example, as shown in FIG. 5, when all the surfaces of the surface that is substantially perpendicular to the panel surface 9 and the surface that is substantially inclined are the diffusing surface 3, the optical panel 1. The light beam incident from the side of the prism array surface 4 is diffused over the entire surface of the prism array surface 4, and the light direction cannot be controlled, and this also serves as the optical panel 1 for controlling the light direction in one direction. Is inappropriate.

  As yet another reference example, as shown in FIG. 8, when the prism shape is entirely composed only of a substantially inclined surface with respect to the panel surface 9, in order to obtain the function of controlling the light direction, the panel surface 9 The slope with a positive slope relative to the mirror surface 2 and the slope with a negative slope as the diffusing surface 3, or vice versa (the slope with a negative slope relative to the panel surface 9 is the mirror surface. It is necessary to unify the inclination direction of the surface and the surface state (whether it is the diffusion surface 3 or the mirror surface 2).

  On the other hand, in the optical panel 1 having the surface configuration shown in FIG. 3 of the present invention, as shown in FIG. 6, the light ray A incident from the prism array surface 4 side of the optical panel 1 is substantially inclined surface of the prism. It is refracted once at (mirror surface 2) and after passing through the panel, it is also refracted when it exits, and it is possible to direct light in the target direction, and a position close to a substantially vertical surface (diffusion surface 3) Since the light ray B incident on the prism is once refracted by the substantially inclined surface (mirror surface 2) of the prism and then diffused by the substantially vertical surface (diffusion surface 3), the light is strongly emitted in the direction opposite to the target direction. However, as shown in FIG. 7, the entire panel is excellent in the effect of controlling the light direction in one direction.

  FIG. 9 shows the results of the light direction control characteristics for the models shown in FIGS. 6 indicates that there are many light beams emitted in the direction in which the curve swells (strong light distribution direction) e, and the model of FIG. 6 shown in FIG. It is understood that the diffusion surface 3, particularly the diffusion surface 3 surface roughness: Ra = 1.5 level) is excellent in the light direction control characteristics. FIG. 9B similarly shows the model of FIG. 6 (diffusion surface 3 surface roughness: Ra = 0.5 level). 9C is the model shown in FIG. 4 (the prism shape is the entire mirror surface 2), and FIG. 9D is the model shown in FIG. 5 (the prism shape is the entire surface diffusing surface 3 (diffusing surface 3 surface roughness: Ra = 1.5). Level).

  Incidentally, as shown in FIG. 10B, when the substantially inclined mirror surface 2 of the prism array surface 4 is formed in a straight line, a part A1 of the light beam A refracted by the mirror surface 2 is diffused substantially vertically. It hits surface 3 and is diffused. For this reason, the light rays diffused on the diffusion surface 3 increase, and it becomes difficult to control light distribution of more light rays in one direction. Therefore, in this example, as shown in FIG. 10A, a refracted slope 50 is formed at the tip portion of the substantially inclined mirror surface 2 on the side close to the diffusion surface 3, and the refracted slope 50 with respect to the panel surface 9 is formed. By making the inclination smaller than the slope part other than the refractive slope 50, the angle of refraction at the refractive slope 50 with a small slope changes, and as a result, the amount of the light ray A1 diffused on the diffusion surface 3 decreases, and more Can be distributed in one direction. Further, the refractive slope 50 of the mirror surface 2 may be finely divided into, for example, three or more surfaces. In this case, the amount of light that can be controlled in one direction can be further increased.

  FIGS. 11-16 has shown an example of the manufacturing process of the metal plate 11 for optical panels for shape | molding the optical panel 1 of the said structure. In the mold part block 10 in which the prism array-shaped surface 14 in the optical panel mold 11 is formed, the diffusion surface forming mold part 13 for forming the diffusion surface 3 and the mirror surface 2 are formed. The mirror surface forming mold part 12 is provided. Here, one diffusion surface forming mold portion 13 corresponds to one diffusion surface 3 (FIG. 6) of the optical panel 1, and one mirror surface forming mold portion 12 corresponds to one mirror surface 2 ( 6), the mold block 10 has a prism array-shaped surface 14 in which a plurality of diffusion surface forming mold portions 13 and mirror surface forming mold portions 12 are continuously arranged. ing. Examples of the material of the mold block 10 include copper, brass, nickel, aluminum, zinc alloy, or a steel material such as S55C plated with copper or nickel to a thickness of about 0.5 to 10 mm. .

  Next, in forming the prism array shaped surface 14 on the mold part block 10 (work), first, as shown in FIG. 11, the first surface 13a for forming the diffusion surface forming mold part 13 is formed. On the second surface 12a (substantially inclined surface) for forming the mirror surface forming mold part 12 by forming the general shape of the diffusion surface forming mold part 13 to be formed on the (substantially vertical surface), The general shape of the mirror surface forming mold part 12 to be formed is formed. As an example of forming such a schematic shape of the prism array shaped surface 14, the reciprocating cutting tool 6 shown in FIG. 12 or the rotary cutting tool 6 ′ shown in FIG. 13 is used. Each of these cutting tools 6 and 6 ′ has a substantially triangular cross section obtained by inverting the cross sectional shape of the prism array shaped surface 14.

  Here, examples of the cutting tool 6 used in the reciprocating cutting method of FIG. 12 include a carbide tool, a single crystal diamond tool, a sintered diamond tool, and the like. The cutting feed rate is preferably about 6 to 7 m / min, and the cutting amount in one cutting is preferably about 30 to 50 μm. On the other hand, examples of the cutting tool 6 ′ used in the rotary cutting method of FIG. 13 include a rotary grindstone. The rotational speed at the time of cutting is preferably about 2000 to 2500 rpm in the case of a rotating grindstone of about φ200, the cutting feed speed is about 15 to 25 m / min, and the cutting amount in one cutting is preferably about 30 to 50 μm.

  Then, the reciprocating cutting tool 6 is reciprocated in the direction indicated by the arrow E in FIG. 12B, or the rotary cutting cutting tool 6 ′ is indicated by the arrow in FIG. 13B. By rotating in the direction, the first surface 13a and the second surface 12a having a schematic shape as shown in FIG. 11 can be formed by cutting.

  Thereafter, blasting is performed on the prism array-shaped surface 14 having the above-described general shape. There are examples of blast particles such as sand and beads, but as the shape of the particles, sand blast having many protrusions is used, and a blast count having a particle diameter of about 500 to 2000 is desirable. Further, as shown in FIG. 14, it is desirable to perform blasting from an oblique direction so that the blast particles only hit the first surface 13a that finally requires the diffusion surface 3. That is, the blast particles mainly collide with the first surface 13a by spraying the blast particles over the entire surface of the roughly shaped prism array-shaped surface 14 from a direction substantially parallel to the second surface 12a. A diffusion surface forming mold portion 13 having a diffusion shape is formed on the surface 13a.

  After that, only the second surface 12a (substantially inclined surface that finally becomes the mirror surface forming mold part 12) of the prism array-shaped surface 14 of the mold part block 10 is used as a mirror surface. An example of this method is shown in FIGS.

  In FIG. 15, single crystal diamond is used as the cutting tool 6. The cross-sectional shape of the blade 7 is a distance S (about 10 to 10) from a substantially vertical surface (surface that finally becomes the diffusion surface forming mold portion 13) in the cross-sectional shape of the final prism array-shaped surface 14 of the mold 11. The shape is offset by 20 μm). Further, the cutting tool 6 made of single crystal diamond is obtained so that a bent surface 51 corresponding to the refracted refractive slope 50 of the optical panel 1 shown in FIG. 10A is obtained on the second surface 12a of the prism array shaped surface 14. A slope 52 is formed on the surface. As a cutting method using this cutting tool 6, a diffusion surface forming mold that finally requires the diffusion surface 3 among the prism array-shaped surfaces 14 of the mold block 10 whose entire surface has a diffusion surface shape. The cutting tool 6 is positioned at a position offset by 10 to 20 μm so as not to contact the portion 13 (substantially vertical surface) so that only the second surface 12a can be cut. The cutting feed rate is preferably about 6 to 7 m / min, and the cutting amount in one cutting is preferably about 5 to 10 μm. At this time, as shown in FIG. 16, the cross-sectional shape of the blade 7 may be a shape having a gradient θ of about 5 ° to 10 ° from the substantially vertical surface of the optical panel mold 11.

  As described above, the mirror surface forming mold portion 12 is formed by finishing the second surface 12a to the mirror surface 2 using the cutting tool 6 made of single crystal diamond, and the target diffusion surface forming mold portion 13 and the mirror surface are formed. An optical panel mold 11 having a prism array shaped surface 14 in which a plurality of forming mold sections 12 are alternately and continuously formed can be manufactured.

  As another method for mirror-finishing the second surface 12a (substantially inclined surface), for example, as shown in FIG. 1, a formed diamond tool 60 formed into a conical shape is formed in advance. It is possible to finish the second surface 12a to the mirror surface 2 by performing a burnishing process that presses against the second surface 12a of the prism array-shaped surface 14 of the mold 11. At this time, if the generatrix of the shaped diamond tool 60 is a curve, it is possible to process the shape in which the substantially inclined surface is a curved surface.

  Thus, after the prism array shaped surface 14 is cut into a rough shape, only the diffusion surface forming mold part 13 forming process by blasting and the mirror forming mold part 12 forming process by mirror finishing are performed. Therefore, compared to the conventional resist coating process, exposure / development process, etching process, and resist removal process, the number of processes until the mold 11 is completed is reduced in the present invention, and the productivity is greatly increased. Will be improved. In addition, since the rough surface is formed by blasting, it is possible to easily process the diffused surface shape as compared with conventional etching, which is extremely advantageous in terms of shape reproducibility and the diffusion surface. There is also an advantage that the accuracy of the shape becomes extremely high, and therefore it is easy to ensure surface roughness for obtaining sufficient light distribution characteristics on the diffusing surface 3 of the molded optical panel 1.

  Here, in the present invention, in the cutting step, the material of the surface to be cut of the mold block 10 is copper plated. For example, it is desirable to perform pure copper plating on a base material such as SUS304 or 420. The plating thickness is, for example, about 100 to 3000 μm. However, considering the time required for plating, the plating thickness is preferably about 100 to 400 μm. Further, by setting the hardness to about Hv 200 to 220, it becomes possible to withstand a molding life of 20000 to 100,000 shots. This embodiment corresponds to claim 1. Thus, by cutting the copper plating with a thickness less than the total thickness to form a prism shape, the life of the cutting tool 6 can be extended and the life of the mold 11 can be extended, and in particular, pure copper plating. Thus, there is no need to worry about quality defects due to variations in the components contained.

  FIGS. 17-19 has shown the other example of the manufacturing method of the metal mold | die 11 for optical panels. In this method, the rough shape processing of the prism array shaped surface 14 is first performed by cutting, and at the same time, the entire surface of the substantially shaped prism array shaped surface 14 is mirror-finished. As a rough shape processing method of the prism array shaped surface 14, it is performed by cutting with a cemented carbide tool, a single crystal diamond tool or the like similar to FIGS. Further, as a method of performing mirror finishing on the entire prism array shaped surface 14, a single crystal diamond tool or a molded diamond tool as shown in FIG. 14 or 15 is used.

  Thereafter, only the second surface 12a to be finally left as the mirror surface forming mold part 12 is coated with the high hardness coating 5. An example of a method for applying the high hardness coating 5 is shown in FIG. The coating type includes TiN, TiAlN, Cr, etc., and the surface hardness is Hv 2500 to 3000. Examples of the coating method include sputtering, ion plating, and vapor deposition. Since these methods are difficult to apply coating to the lizard part of the shape, the coating as shown in FIG. 17 is applied only to the substantially inclined surface (the mirror-finished surface to be the mirror surface forming mold part 12). In addition, the substantially vertical surface (first surface 13a) is not coated or has an angstrom level thickness. In FIG. 17, arrows L indicate the coating direction, 20 indicates a coating evaporation source, and 21 indicates a workpiece mounting table.

  Then, as shown in FIG. 18, after coating the high-hardness coating 5 only on the substantially inclined surface (the mirror-finished surface serving as the mirror-forming mold part 12), the entire surface of the prism array-shaped surface 14 is blasted. Apply. At this time, as shown by an arrow G in FIG. 18, by performing blasting from an angle so that the blast particles collide only with the first surface 13 a that finally becomes the diffusion surface forming mold portion 13, high hardness is achieved. The surface of the coating 5 remains in a mirror shape, so that finally, as shown in FIG. 19, the diffusion surface forming mold part 13 is formed only on the first surface 13a not coated with the high-hardness coating 5. In addition, the surface of the high-hardness coating 5 becomes the mirror surface forming mold part 12.

  FIG. 20 shows an example in which the cutting surfaces 6a on both sides of the cutting tool 6 have a diffusing surface shape as still another example of the method for manufacturing the optical panel mold 11. FIG. As shown in FIG. 20, after the prism array-shaped surface 14 of the mold 11 is cut into a rough shape with a cutting tool 6 configured in advance with a diffusing surface shape, only the substantially inclined second surface 12a is mirror-finished. Thus, the prism shape of the target mold part block 10 can be obtained. Here, when the cutting tool 6 is a cemented carbide tool, the cutting feed rate can be about 6 to 7 m / min, and the cutting amount in one cutting can be about 50 to 100 μm. Processing is possible. On the other hand, when the cutting tool 6 is a sintered diamond tool, the cutting feed rate can be about 6 to 7 m / min, and the cutting amount in one cutting can be about 30 to 50 μm. Although the processing time is long, the accuracy of the shape of the diffusion surface is high, which is advantageous in terms of shape reproducibility. The second surface 12a can be mirror-finished using a single crystal diamond tool or a molded diamond tool as shown in FIG. 15 or FIG.

  FIG. 21 shows a modification of FIG. Here, a sintered diamond cutting tool is used as the cutting tool 6, and one of the cutting surfaces 6 b is a smooth surface and the other cutting surface 6 c is a diffusing surface. The diffusion surface forming mold part 13 and the mirror surface forming mold part 12 can be simultaneously formed on the mold part block 10, thereby further reducing the number of manufacturing steps. Become.

  FIG. 22 shows still another example of the manufacturing method of the optical panel mold 11. Here, the prism array-shaped surface 14 is processed into a schematic shape, and at the same time, the entire surface of the prism array-shaped surface 14 is mirror-finished, and then the first surface 13 a is processed into a diffusing surface shape using the cutting tool 6. As the mirror finishing method, a single crystal diamond tool or a molded diamond tool as shown in FIG. 15 or 16 can be used. Here, when the first surface 13a is processed into a diffusing surface shape by using the cutting tool 6, the sectional shape of the diffusing surface shape in which the tip of the cutting tool 6 is formed on the substantially vertical first surface 13a. Is used, and the cutting tool 6 is fed by a minute pitch (preferably the feed pitch is preferably about 1 to 5 μm), whereby the first surface 13a is cut into a diffusing surface shape to form a diffusing surface forming gold. The mold part 13 can be formed. The cutting tool 6 is preferably a single crystal diamond tool or a sintered diamond tool. At this time, by making the lower surface of the cutting edge 7a of the cutting tool 7 of the cutting tool 6 coincide with the substantially inclined surface shape of the prism array-shaped surface 14, the rough shape processing of the prism array-shaped surface 14 and the mirroring of the substantially inclined surface shape, In addition, it is possible to process the diffused surface shape of a substantially vertical surface at the same time, thereby further reducing the number of manufacturing steps. Further, there is an advantage that the accuracy of the diffusing surface shape becomes extremely high by feeding and moving the cutting diamond bit by fine pitch.

  FIG. 23 shows still another example of the manufacturing method of the optical panel mold 11. In this example, using the discharge electrode 90 having a cross-sectional shape obtained by inverting the cross-sectional shape of the prism array-shaped surface 14, the prism array-shaped surface 14 is processed and formed into a schematic shape, and at the same time, the first surface 13a and the second surface 13 The surface 12a is processed into a diffusing surface shape, and thereafter, only the second surface 12a is mirror-finished. Here, as a material of the discharge electrode 90 used for processing into the substantially shaped prism array shaped surface 14, for example, carbon or copper is desirable. Then, by using the current value to be passed through the discharge electrode 90 and the current on / off interval as parameters, the prism array shape as shown in FIG. It is possible to form a diffused surface shape on the entire surface 14. Finally, the second surface 12a can be mirror-finished by using a single crystal diamond tool or a molded diamond tool as shown in FIG. 15 or FIG.

  As a modification of FIG. 23, as shown in FIG. 24, it is also possible to form a diffusing surface shape for the entire shape simultaneously with the processing of the rough shape of the prism array shaped surface 14 by electric discharge machining with the discharge wire 23. It is. According to this method, a curved surface shape or the like can be processed, and there is an advantage that the degree of freedom of the prism array shape is increased.

  25 and 26 show still another example of the manufacturing method of the optical panel mold 11. In this example, after the roughly shaped prism array shaped surface 14 is formed by the vibration cutting method, the first surface 13a is processed into a diffusing surface shape to form the diffusing surface forming mold part 13, and then the first The second surface 12a is mirror-finished to form the mirror surface forming mold part 12. Here, an ultrasonic vibrator 26 or a piezo element or the like is installed in the clamp portion 25 of the cutting tool 6 used for vibration cutting, and cutting is performed while applying minute vibrations during cutting. Then, after processing the prism array shaped surface 14 into a schematic shape, the first surface 13a of the prism array shaped surface 14 is cut into a diffusing surface shape. At this time, by performing cutting while repeating minute vibrations in the left-right direction indicated by the arrow E in FIG. 25, a desired diffusion surface shape can be obtained on the first surface 13a. Here, as vibration conditions, for example, those having an amplitude of about 5 to 20 μm and a frequency of about 15 to 25 kHz are desirable. Further, according to this method, as shown in FIG. 26, it is possible to form a diffusing surface shape having a concavo-convex shape in a direction perpendicular to the cutting direction E. At this time, the tip of the cutting tool 6 shown in FIG. By using together with a method of moving each by a minute pitch, the two-dimensional diffusion surface forming mold part 13 can be easily formed. In FIG. 26, G indicates a substantially vertical surface before processing, and H indicates a substantially vertical surface after processing.

  FIG. 27 shows still another example of the manufacturing method of the optical panel mold 11, and the second surface 12 a (roughly inclined surface that finally becomes the mirror surface forming mold section 12) once roughened is shown. When mirror-finishing with the cutting tool 6, the blade 7 of the cutting tool 6 is spaced from the diffusion surface forming mold part 13 which has been roughened in advance within a range of 10 μm to 30 μm (hereinafter referred to as offset amount M). ) Is opened and cutting is performed. As the cutting tool 6, for example, a blade 7 made of single crystal diamond is used. The cross-sectional shape of the blade 7 is substantially V so that only the second surface 12a can be cut by opening the predetermined offset amount M so as not to contact the diffusion surface forming mold portion 13 of the prism array-shaped surface 14. It has a letter shape.

  Accordingly, the workpiece (mold block 10) having the entire prism array-shaped surface 14 in advance having a diffusing surface shape does not finally come into contact with the diffusing surface forming mold portion 13 that requires a diffusing surface. Thus, the cutting tool 6 is positioned so that the cutting tool 6 is offset from the diffusion surface forming mold part 13 within a range of 10 μm or more and 30 μm or less, and the cutting feed rate is set to about 6 to 7 m / min. Then, only the second surface 12a is cut. Here, if the offset amount M is less than 10 μm, the diffusion surface forming mold portion 13 that has been roughened in advance by the cutting chips generated during the cutting of the second surface 12a is rubbed, and therefore the surface roughness is reduced. Accordingly, the optical panel 1 molded with the mold 11 cannot obtain sufficient optical characteristics. On the contrary, as shown in FIG. 28B, when the offset amount M ′ is larger than 30 μm, in the optical panel 1 molded with this mold 11, the area of the mirror surface 2 is reduced by the offset amount M. Therefore, the ratio of light distribution on one side is reduced, and sufficient optical characteristics cannot be obtained.

  According to this method, the offset amount M of the cutting tool 6 with respect to the diffusion surface forming mold part 13 is set in a range of 10 μm or more and 30 μm or less, preferably in a range of 20 μm or more and 25 μm or less. The surface roughness of the diffusion surface forming mold part 13 can be secured, and the optical panel 1 obtained with the mold 11 has an increased ratio of light distribution to one side as shown in FIG. More desirable optical characteristics can be obtained.

  In the example of FIG. 27, the case where the cutting tool 6 is offset along the diffusion surface forming mold portion 13 has been described. However, for example, as shown in FIG. You may make it offset by giving the gradient (theta) of about 5-10 degrees. Even in this case, more desirable optical characteristics of the optical panel 1 can be obtained by setting the offset amount M of the cutting tool 6 with respect to the diffusion surface forming mold portion 13 in the range of 10 μm to 30 μm and cutting. Can do.

  FIG. 30 shows still another example of the manufacturing method of the optical panel mold 11, and the second surface 12 a (roughly inclined surface that finally becomes the mirror surface forming mold part 12) once roughened is shown. When mirror cutting is performed with the cutting tool 6, the cutting tool 6 is cut so that a single cutting amount N by the blade 7 is 5 μm or less. This is because when the cutting depth N is greater than 5 μm, the amount of cutting chips generated increases, and the diffusion surface forming mold portion 13 that has been roughened in advance is rubbed. As the cutting tool 6, for example, a blade 7 made of single crystal diamond is used. Accordingly, when cutting the second surface 12a, the offset amount M of the cutting tool 6 with respect to the diffusion surface forming mold portion 13 is set in the range of 10 μm or more and 30 μm or less, as in the embodiment of FIG. In addition, the cutting depth N is set to 5 μm or less, preferably 1 μm or more and 2.5 μm or less, and the cutting feed rate is set to about 6 to 7 m / min, and only the second surface 12a is cut. To do. According to this method, since the amount of cutting swarf generated in one cutting is very small, the diffusing surface forming mold part 13 previously roughened by cutting swarf during cutting is rubbed. Can be prevented. Accordingly, the surface roughness of the diffusing surface forming mold part 13 can be secured, and the accuracy of the mirror surface shape can be improved by setting the cutting depth N at one time when the mirror surface forming mold part 12 is cut to 5 μm or less. This is advantageous in terms of shape reproducibility, and the optical panel 1 obtained with such a mold 11 can obtain more desirable optical characteristics.

  FIG. 31 shows still another example of the method of manufacturing the optical panel mold 11, and the second surface 12 a (roughly inclined surface that finally becomes the mirror surface forming mold part 12) once roughened is shown. When cutting with the cutting tool 6, it cuts so that the sum total of the final cutting amount L may become the range of 10 micrometers or more and 30 micrometers or less. If it is smaller than 10 μm, the unevenness once roughened remains without being completely removed, and if it is larger than 30 μm, in the optical panel 1 molded with this mold 11, it is shown in FIG. 32 (b). As described above, since the proportion of light reflected in the direction opposite to the direction in which light distribution is desired increases, sufficient light distribution characteristics cannot be obtained. As the cutting tool 6, for example, a blade 7 made of single crystal diamond is used. Accordingly, when cutting the second surface 12a, the offset amount M of the cutting tool 6 with respect to the diffusion surface forming mold portion 13 is set in the range of 10 μm or more and 30 μm or less, as in the embodiment of FIG. Then, only the second surface 12a is cut so that the cutting feed rate is about 6 to 7 m / min, and the total of the final cutting amounts L is in the range of 10 μm to 30 μm. According to this method, the unevenness formed on the second surface 12a once roughened can be completely scraped off. In particular, the smoothness of the mirror surface forming mold part 12 can be secured by cutting the final cutting amount L in the range of 10 μm or more and 30 μm or less, preferably 20 μm or more and 25 μm or less. As shown in FIG. 32 (a), the optical panel 1 obtained with the simple mold 11 can ensure the surface roughness of the diffusing surface 3, and at the same time, reflects light in the direction opposite to the direction in which light is desired to be distributed. As a result of the decrease, sufficient light distribution characteristics can be obtained.

  Further, in each of the embodiments, the surface roughness of the final mold prism-shaped roughened diffusion surface forming mold part 13 (substantially vertical surface) is Ra 0.66 or more and 1.5 or less. Is desirable. This embodiment corresponds to claim 2. FIG. 33 shows the relationship between the surface roughness Ra and the light distribution ratio (%) of the optical panel 1. Here, by setting the surface roughness Ra of the diffusion surface forming mold part 13 to 0.66 or more and 1.50 or less (preferably 0.66 or more and 1.40 or less), the light distribution of the optical panel 1 is achieved. The required 60.2% can be ensured as a proportion, and sufficient optical characteristics of the optical panel 1 can be ensured. In order to obtain more effective light distribution characteristics, it is desirable that the surface roughness Ra is in the range of 0.88 to 1.19. The light distribution ratio (%) is a “one-side light beam (light beam covering region / total light beam)” when the 0 ° direction is used as a boundary in the light distribution map (see FIG. 9).

  Further, the average aspect ratio of the surface shape of the final mold prism-shaped roughened diffusion surface forming mold portion 13 (substantially vertical surface) can be obtained to obtain the necessary light distribution ratio of the optical panel 1. It is desirable to set it above a predetermined value. This embodiment corresponds to claim 3. FIG. 34 shows the relationship between the average aspect ratio of the surface shape of the diffused surface forming mold portion 13 roughened and the light distribution ratio of the optical panel 1 molded with this mold 11. The surface shape referred to here is the irregularities shown in the surface roughness data profile of FIG. 35 measured by a surface roughness measuring machine, and a partially enlarged view thereof is shown in FIG. The average aspect ratio (= 1 / n × (b1 / a1 + b2 / a2 + b3 / a3 +... + Bn / an) can be calculated from Fig. 36. By setting the average aspect ratio to 0.61 or more, FIG. As shown, the required light distribution ratio of 60.2% can be secured for the optical panel 1. To obtain more effective light distribution characteristics, the average aspect ratio is 0.73 or more. Is desirable.

  FIG. 37 shows a surface roughness data profile in the final diffused-diffusion-surface-forming mold part 13 having a prism prism shape. This embodiment corresponds to claim 4. Here, an arbitrary upper limit value X and a lower limit value Y shown in FIG. 37 are set with respect to the center of the surface roughness of the diffusion surface forming mold part 13 (substantially vertical surface), and the range between them is set as a reference value range. The number of points in the surface roughness data profile is classified into the number of points that fall within the reference value range Z and the number of points that exceed the reference value range Z, and the number of points in the reference value range Z. The surface roughness is evaluated by the ratio of the number of points exceeding this. FIG. 38 shows the relationship between the ratio of the number of points exceeding the reference value range Z and the light distribution ratio when the upper limit value X and the lower limit value Y are each set to a width of 1.5 μm with respect to the surface roughness center. Is shown. Here, by setting the ratio of the number of points exceeding the reference value range Z to 8% or more, the necessary light distribution ratio of the optical panel 1 of 60.2% can be secured. In order to obtain more effective light distribution characteristics, the ratio of the number of points exceeding the reference value range Z is preferably 19% or more.

  Further, in each of the above embodiments, it is desirable that the surface or surface layer of the diffusion surface forming mold portion 13 having the roughened mold 11 is made of a material having wear resistance. This embodiment corresponds to claim 5. As a method of imparting abrasion resistance to the surface or surface layer of the diffusion surface forming mold part 13, coating such as TiN, TiAlN, Cr, etc. by sputtering, ion plating, vapor deposition, etc., Cr plating, or Ni plating And the like. Further, the surface hardness is Hv 1000 to 3000, and it is possible to protect the roughened diffusion surface forming mold portion 13 (substantially vertical surface) and to prevent wear due to molding. Moreover, the lifetime of the blade 7 can be ensured and the optical characteristics of the optical panel 1 can be ensured. Furthermore, it is possible to extend the life of the mold 11 to 5 to 20 times as compared with the case where no wear resistant coating is applied.

  Further, it is desirable to coat the surface of the diffusion surface forming mold part 13 having a roughened surface with a protective coating having a thickness of 0.1 μm or more and 0.5 μm or less. This embodiment corresponds to claim 6. That is, since the surface roughness of the diffusion surface forming mold portion 13 (substantially vertical surface) is Ra 0.66 to 1.41, by making the thickness of the protective coating 0.1 μm or more and 0.5 μm or less, The rough surface shape of the diffusion surface forming mold part 13 is not filled with the protective coating, and the surface roughness can be ensured. Further, in order to provide wear resistance to the diffusion surface forming mold part 13 and to secure the light distribution characteristics of the optical panel 1, the thickness of the protective coating is set to 0.2 μm or more and 0.3 μm or less. It is particularly desirable to do so.

  Further, the protective coating is preferably Ni plating. This embodiment corresponds to claim 7. This Ni plating can be performed easily, and a uniform thin film coating is possible, thereby simplifying the coating process.

It is a perspective view of the metal mold | die for optical panels of an example of embodiment of this invention. It is sectional drawing of the optical panel shape | molded with the metal mold | die same as the above. It is an expanded sectional view of the a part of FIG. It is explanatory drawing of light control in case a prism array surface same as the above is a full-surface mirror surface. It is explanatory drawing of light control in case a prism array surface same as the above is a whole surface diffusion surface. FIG. 4 is an enlarged cross-sectional view of part b of FIG. 3, and is an explanatory diagram of light beam control when a substantially vertical surface of the prism array surface is a diffusion surface and a substantially inclined surface is a mirror surface. It is explanatory drawing of the light beam control of FIG. It is sectional drawing of the optical panel of other embodiment. It is a figure explaining the relationship between a prism surface state same as the above, and light distribution. (A) is explanatory drawing of the reflective state of the light ray in the b section of FIG. 3, (b) is explanatory drawing of the reflective state of the light ray when not providing a refractive slope. It is a perspective view of the state which processed the prism array shape surface same as the above into a rough shape. (A) is the figure which looked at the case where the schematic shape of a prism array shape surface same as the above is formed with a reciprocating cutting tool from the c direction of FIG. 11, (b) is the figure seen from the d direction of FIG. (A) is the figure which looked at the case where the schematic shape of a prism array shape surface same as the above is formed with a rotary cutting tool from the c direction of FIG. 11, (b) is the figure seen from the d direction of FIG. It is explanatory drawing in the case of blasting to the 1st surface of the prism array shape surface of a metal mold | die part block same as the above. It is explanatory drawing of an example in the case of performing a mirror surface process on the 2nd surface of the prism array shape surface of a metal mold | die part block same as the above. It is explanatory drawing of the other example in the case of performing a mirror surface process on the 2nd surface of the prism array shape surface of a metal mold | die part block same as the above. It is sectional drawing of other embodiment. It is explanatory drawing of the collision direction of the particle | grains in blast processing same as the above. It is explanatory drawing of the diffusion surface shape after blasting same as the above. It is sectional drawing of other embodiment. It is sectional drawing of other embodiment. It is sectional drawing of other embodiment. It is sectional drawing of other embodiment. It is sectional drawing of other embodiment. It is sectional drawing of other embodiment. It is the figure seen from the arrow F direction of FIG. It is sectional drawing of other embodiment. (A) (b) is a schematic side view explaining the relationship between the offset amount of a cutter same as the above, and the light distribution efficiency of an optical panel. It is sectional drawing of other embodiment. It is sectional drawing of other embodiment. It is sectional drawing of other embodiment. (A) (b) is a schematic side view explaining the relationship between the offset amount of a cutter same as the above, and the light distribution efficiency of an optical panel. It is a graph which shows the relationship between the light distribution ratio and surface roughness in other embodiment. It is a graph which shows the relationship between the light distribution ratio and average aspect-ratio in other embodiment. It is a graph which shows the relationship between the scanning distance and surface height in other embodiment. It is explanatory drawing of an average aspect ratio same as the above. It is a graph which shows the data of the surface roughness in other embodiment. It is a graph which shows the relationship between the light distribution ratio in other embodiment, and the point ratio exceeding a reference value range. It is a schematic block diagram of the conventional OHP. It is sectional drawing of the conventional Fresnel lens. (A)-(d) is a manufacturing-process figure of the metal mold | die for shape | molding the conventional Fresnel lens.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical panel 2 Mirror surface 3 Diffusion surface 4 Prism array surface 5 High-hardness coating 6 Cutting tool 7 Cutting tool 7a Cutting surface 9 Panel surface 10 Mold part block 11 Optical panel die 12 Mirror surface forming die part 12a 2nd Surface 13 Diffusion surface forming mold portion 13a First surface 14 Prism array shaped surface L Final cut amount M Interval (offset amount)
N Cutting depth per cut X Upper limit value Y Lower limit value Z Reference value range

Claims (7)

  It consists of a diffusion surface forming mold part for forming a diffusion surface and a mirror surface forming mold part for forming a mirror surface, and the light direction can be controlled by a prism shape having the diffusion surface and the mirror surface. An optical panel mold for molding an optical panel, the surface of a surface to be cut of a mold part block in which a diffusion surface forming mold part and a mirror surface forming mold part are formed by cutting. An optical panel mold characterized in that the material is made of copper plating.   2. The optical panel mold according to claim 1, wherein the surface roughness of the diffusion surface forming mold part is Ra 0.66 or more and 1.5 or less.   3. An optical panel mold according to claim 2, wherein the average aspect ratio of the surface shape of the mold part for forming the diffusion surface is set to 0.61 or more capable of obtaining a necessary light distribution ratio of the optical panel. Type.   An arbitrary upper limit and lower limit are set for the surface roughness center of the diffusion surface forming mold part, and the range between them is set as a reference value range, among the number of points in the surface roughness data profile, 3. The optical system according to claim 2, wherein the number of points falling within the reference value range and the number of points exceeding the reference value range are classified, and the ratio of the number of points exceeding the reference value range is 8% or more. Panel mold.   5. The optical panel mold according to claim 1, wherein a surface or a surface layer of the diffusion surface forming mold section is made of a material having wear resistance. 6.   6. The optical panel mold according to claim 5, wherein the surface of the diffusion surface forming mold part is coated with a protective coating having a thickness of 0.1 μm or more and 0.5 μm or less.   The optical panel mold according to claim 6, wherein the protective coating is Ni plating.

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