JP5685129B2 - Method for manufacturing light guide plate - Google Patents

Description

  The present invention relates to a method of manufacturing a light guide plate, and more particularly to a method of manufacturing a light guide plate that emits light incident from a part of its end face as uniform scattered light from one surface thereof.

  In surface light emitters used in liquid crystal display devices, lighting fixtures, sign displays, etc., so-called edges that emit light incident from the end face of the light guide plate as uniform scattered light from one side of the light guide plate are realized in order to achieve a reduction in thickness. Various types of light systems have been proposed.

  18 is a schematic rear view of a surface light emitter using a conventional light guide plate, and FIG. 19 is a cross-sectional view taken along the line XIX-XIX shown in FIG.

  With reference to these drawings, the surface light emitter 70 is disposed on the entire surface of a transparent rectangular light guide plate 71 made of acrylic resin and one end face of the light guide plate 71 in the short direction (vertical direction in FIG. 18). A light source 11 composed of a light emitting diode (LED), a reflection tape 12 adhered to the entire surface of the light guide plate 71 excluding one end surface, and a diffusion sheet installed on the entire surface of the front surface of the light guide plate 71. 13 and the reflection sheet 14 installed on the entire other surface on the back side of the light guide plate 71. In addition, on the back surface of the light guide plate 71, a plurality of line grooves 72 for scattered light having a V-shaped cross section and linearly extending to both ends in the short direction are formed in parallel at various intervals.

  Then, as indicated by the broken-line arrows in FIG. 19, the light that enters the light guide plate 71 from the light source 11 directly or leaks to the end face side and the back face side is reflected on the reflective tape 12 and the reflective sheet 14. The light is reflected and one surface on the front side emits light through the diffusion sheet 13. Further, the line grooves 72 are set such that the width, the number, and the interval thereof are set so that one surface of the light guide plate 71 emits high illuminance and uniform scattered light. Specifically, the degree of light scattering in the area where the light from the light source 11 is difficult to reach is increased by reducing the distance between the line grooves 72 as the distance from the light source 11 increases. Therefore, along with the light diffusion effect by the diffusion sheet 13, one surface of the light guide plate 71 emits light uniformly.

In addition, as a method of forming such a linear groove 72 in the light guide plate 71, a method of forming with a blade, a so-called linear V-groove method of irradiating a laser (for example, Patent Document 1), or molding manufactured with a mold. There is a method. Further, each of the line grooves 72 is formed in parallel, but there is also a structure in which each of the line grooves 72 is formed in a lattice shape by intersecting each other. The production of the light guide plate by the linear V-groove method described above is a method suitable for a small lot original design or the like. Also, the production of the light guide plate by a molding method is most used as a liquid crystal display application, and is a production method suitable for mass production.
Furthermore, another method for manufacturing the light guide plate is so-called silk printing in which special fluorescent ink is applied to the back surface of the light guide plate in a specific pattern and the scattered light is adjusted to uniformly emit light on one side of the light guide plate. There is a method. The manufacture of a light guide plate by a silk printing method is most used for large display applications, and is a manufacturing method suitable for mass production in the same manner as a molding method.

Japanese Patent No. 2927392

  In the conventional light guide plate manufacturing method as described above, the design of the line groove pattern (line width, spacing, etc.) and the application pattern of the special fluorescent ink to make the light emission from the front surface uniform is suitable for the scattered light. It was necessary to repeat complex calculations and experiments for amplification. For this reason, a high level of expertise is required, and it takes time and effort.

  Further, in the case of the linear V-groove method, if the light guide plate has low smoothness, the depth and line width of the formed line groove may change, and there is a possibility that the light does not emit uniformly as designed. Furthermore, when the pattern of the line grooves of the light guide plate is formed in, for example, a lattice shape, it looks like a grid, so that it is essential to install a diffusion sheet. Therefore, the usage has been limited.

  Further, in the case of the molding method, it is necessary to create a mold, so that a small lot is expensive.

  Further, in the case of the silk printing method, the quality of the light guide plate is likely to become unstable due to the surrounding environment (temperature, humidity, etc.) when printing the special fluorescent ink on the light guide plate. Further, since it is necessary to prepare a plate for use in printing, the cost is high.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a manufacturing method for easily manufacturing a light guide plate that emits light with uniform brightness on one side.

  In order to achieve the above object, according to the first aspect of the present invention, the interior of the substrate is made of at least a transparent substrate, and light incident from a part of its end surface is converted into uniform scattered light from a predetermined area on one surface of the substrate. A method of manufacturing a light guide plate that emits light, and assumes a planar area corresponding to the size of a predetermined area of the substrate, the edge portion on the side corresponding to the end face in the planar area is a bright portion with high brightness, and the plane from the bright portion The step of obtaining the image data in which the gradation is gradually changed in the portion between these, and the image data is divided into a plurality of image areas, and the portion separated by the maximum distance in the area is divided into a plurality of image areas. Using the process of calculating the average image density and the laser beam whose output is controlled to be large or small according to the magnitude of the density, the output corresponding to each of the average image density and the image area on the other side of the substrate. In which the position corresponding to each of the center and a step of forming a dot groove.

  If comprised in this way, the output of a laser beam is controlled by the density of the image data corresponding to the predetermined area of a board | substrate.

  According to a second aspect of the present invention, in the configuration of the first aspect of the present invention, the substrate has a rectangular shape in plan view in which the entire one surface is a predetermined area, and part of the end surface is one of the short sides of the substrate. The entire end surface, which corresponds to the dark portion in the image data, is the entire other end surface in the lateral direction of the substrate.

  If comprised in this way, only the light will enter from the one end surface of a board | substrate, and the whole surface of the one surface will light-emit uniformly.

  According to a third aspect of the present invention, in the configuration of the second aspect of the present invention, the image area is obtained by dividing the image data into a grid pattern based on a predetermined resolution.

  If comprised in this way, the number of the dot grooves arrange | positioned uniformly by the resolution will change.

  According to a fourth aspect of the present invention, in the configuration of the first aspect of the present invention, the output of the laser beam is controlled at a plurality of stepped output levels, and for each of the output levels. The image density within a predetermined range corresponds.

  If comprised in this way, control of a laser beam will become easy.

  According to a fifth aspect of the present invention, in the configuration of the first aspect of the present invention, the dot groove has a rotationally symmetric shape similar to a spherical crown shape or a truncated cone shape.

  If comprised in this way, the light which injected into the dot groove | channel from the inside of a board | substrate will reflect efficiently.

  The invention according to claim 6 is a method of manufacturing a light guide plate, wherein the inside is made of at least a transparent substrate, and light incident from a part of its end face is emitted as uniform scattered light from a predetermined area on one side of the substrate. Assuming a plane area corresponding to the size of the predetermined area of the board, the edge part on the side corresponding to the end face in the plane area is a dark part with low brightness, and the part farthest from the dark part in the plane area is brightness A step of acquiring image data in which the gradation changes gradually in a portion between these, a step of dividing the image data into a plurality of image areas, and calculating an average image density of each image area, Using laser light whose output is controlled to be small or large depending on the density, the output corresponding to each of the average image density, the position corresponding to the center of each image area on the other side of the substrate It is obtained and forming a dot groove.

  If comprised in this way, the output of a laser beam is controlled by the density of the image data corresponding to the predetermined area of a board | substrate.

  As described above, according to the first aspect of the present invention, since the output of the laser light is controlled by the density of the image data corresponding to the predetermined area of the substrate, the manufacture of the light guide plate in which the predetermined area emits light with uniform brightness. Becomes easy.

  In addition to the effect of the invention described in claim 1, the invention described in claim 2 is efficient in that it emits light uniformly because the entire surface of one surface emits light evenly when light is incident from one end surface of the substrate. The light guide plate can be easily manufactured.

  According to the third aspect of the invention, in addition to the effect of the second aspect of the invention, since the number of dot grooves arranged uniformly varies depending on the resolution, more efficient and uniform light emission is possible.

  In addition to the effects of the invention according to any one of claims 1 to 3, the invention according to claim 4 can easily control the laser beam, so that the processing of the laser beam becomes faster and the productivity is improved. To do.

  In addition to the effect of the invention according to any one of claims 1 to 4, the invention described in claim 5 efficiently reflects light incident on the dot groove from the inside of the substrate, and therefore the light guide plate having high luminous efficiency. It becomes.

  According to the sixth aspect of the present invention, since the output of the laser light is controlled by the density of the image data corresponding to the predetermined area of the substrate, it becomes easy to manufacture a light guide plate that emits light with a uniform brightness in the predetermined area.

It is a schematic rear view of the surface light emitter using the light guide plate according to the first embodiment of the present invention. It is sectional drawing of the II-II line shown in FIG. FIG. 3 is an enlarged view of a portion X shown in FIG. 2. It is sectional drawing of the IV-IV line shown in FIG. It is a figure which shows the image data used for manufacture of the light-guide plate shown in FIG. It is a schematic diagram which shows the head part vicinity of the carbon dioxide laser processing machine used for manufacture of the light-guide plate shown in FIG. It is the schematic diagram which showed the manufacturing method of the light-guide plate shown in FIG. It is a figure which shows the image data for manufacturing the light-guide plate by other embodiment of this invention. It is a figure which shows the image data for manufacturing the light-guide plate by further another embodiment of this invention. It is a schematic front view which shows the light-guide plate of Example D1, Comprising: The measurement area of illuminance is shown with a dashed-two dotted line. It is a graph which shows the average illumination intensity of the measurement area group for every distance Y from the light source of Examples D1-D3. (1) is a graph which shows the average average illumination intensity of Examples D1-D3, (2) shows an average light guide rate. It is a graph which shows the average illumination intensity of the measurement area group for every distance Y from the light source of Example D1, D4, D5. (1) is a graph showing the overall average illuminance of Examples D1, D4, and D5, and (2) shows the average light guide rate. It is a graph which shows the average illumination intensity of the measurement area group for every distance Y from the light source of Example D1, D6, D7. (1) shows the average illuminance of Examples D1, D6 and D7 as a whole, and (2) shows the average light guide rate. (1) shows the overall average illuminance of Examples D8 to D17, and (2) shows the average light guide rate. It is a schematic rear view of the surface light-emitting body using the conventional light-guide plate. It is sectional drawing of the XIX-XIX line shown in FIG.

  1 is a schematic rear view of a surface light emitter using a light guide plate according to a first embodiment of the present invention, FIG. 2 is a sectional view taken along line II-II shown in FIG. 1, and FIG. FIG. 4 is an enlarged view of a portion X indicated by 2 and FIG. 4 is a cross-sectional view taken along line IV-IV shown in FIG.

Referring to these drawings, the surface light emitter 1 has the same configuration as the surface light emitter shown in FIG. 18 of the conventional example except for the shape of the scattered light dot groove 21 formed on the light guide plate 10. It is. That is, a rectangular substrate made of transparent acrylic resin is used for the light guide plate 10, and a plurality of dot grooves 21 are formed in a lattice pattern at equal intervals on the back surface. That is, the vertical and horizontal distances Q ₁ and Q ₂ between the dot grooves 21 shown in FIG. 4 are the same.

  Further, the dot groove 21 is formed in a rotationally symmetric shape similar to the truncated cone shape, and the depth D is formed so as to increase as the distance from the light source 11 increases. Therefore, as the distance from the light source 11 increases, the surface area of the dot groove 21 in the light guide plate 10 increases, and the degree of light scattering increases. For this reason, the illuminance due to the light incident from the light source 11 decreases as it travels through the light guide plate 10, but a large amount of scattered light in an area where the illuminance is relatively small due to the dot groove 21 corresponding to the depth D increasing. To emit. Therefore, by balancing the illuminance and the scattered light as described later, the scattered light is uniformly emitted from the entire front surface, which is a predetermined area that emits the scattered light in the light guide plate 10.

  Furthermore, since the dot groove 21 is formed in a rotationally symmetric shape similar to the truncated cone shape as described above, the light incident on the light guide plate 10 is efficiently reflected. Therefore, the light guide plate 10 with high luminous efficiency is obtained. Further, unlike the line groove of the conventional light guide plate, the dot groove 21 is inconspicuous because it is difficult to be seen.

  Next, image data and a carbon dioxide laser processing machine used when manufacturing the light guide plate 10 will be described.

  FIG. 5 is a diagram showing image data used for manufacturing the light guide plate shown in FIG.

  Referring to the figure, a plane area 26 corresponding to the size of a predetermined area (the entire front surface) of the light guide plate shown in FIG. And in this plane area 26, the edge part of the side corresponding to the one end surface of the light-guide plate in which the light source 11 is located is set to the white bright part 27 with high brightness, and in the plane area 26 from the bright part 27 A portion that is a maximum distance away is set as a black dark portion 28 with low brightness. A so-called gradation process is performed between the bright portion 27 and the dark portion 28 so that the density gradually changes.

  Such image data 25 can be easily created by general graphic software such as CORE RAW (CORE RAW is a registered trademark).

  FIG. 6 is a schematic view showing the vicinity of the head portion of a carbon dioxide laser processing machine used for manufacturing the light guide plate shown in FIG.

  Referring to the drawing, a carbon dioxide laser processing machine 30 guides laser light 31 generated from a laser oscillation device (not shown) with a plurality of mirrors (not shown), and condenses the laser light 31 with an optical lens 32. Then, the focused laser beam 31 is irradiated onto the light guide plate 10 at one point, thereby forming the non-mirror surface dot grooves 21. In the carbon dioxide laser processing machine 30, a head portion 37 including a plurality of mirrors and optical lenses 32 moves on the light guide plate 10 under the control of the X axis and the Y axis, and irradiates the laser beam 31 vertically. A so-called XY plotter type is used. The XY plotter type carbon dioxide laser processing machine 30 is suitable for cutting a thick material, engraving, and processing for a wide area. Further, as indicated by the arrows in the figure, the size of the diameter R of the dot groove 21 can be adjusted by moving the optical lens 32 up and down in the Z-axis direction.

  In addition, the output of the laser beam 31 of the carbon dioxide laser processing machine 30 used in this embodiment can be set to 16 steps. The size of the output is controlled by the above-described 16 levels according to the density of each of the image areas described later.

  Next, the manufacturing method of the light-guide plate 10 using such a carbon dioxide laser processing machine 30 and the image data mentioned above is demonstrated.

  FIG. 7 is a schematic view showing a manufacturing method of the light guide plate shown in FIG.

  First, referring to (1), the image data 25 shown in FIG. 5 is divided into a grid pattern based on a predetermined resolution (for example, 17 dpi) to create a plurality of image areas 35. Then, the average image density of each image area 35 is calculated.

  Next, referring to (2), the head portion 37 of the carbon dioxide laser processing machine is moved to the position corresponding to the center of each of the image areas 35 on the other surface (back surface) of the substrate 17 made of transparent acrylic resin. As shown by, the X-axis or Y-axis direction is controlled and moved.

  Next, referring to (3), as described above, the output of the laser beam 31 is controlled to 16 levels according to the density of the image area 35 in the carbon dioxide laser beam machine. A dot groove 21 is formed by irradiating one point of laser light 31 at a position corresponding to each center with an output corresponding to each of the average densities. At this time, the vertical position of the head portion 37 (the vertical position of the optical lens) is always kept constant. As a result, the dot groove 21 having a large depth is formed in the image area 35 having a large average density.

  Next, referring to (4), when the dot grooves 21 are formed in all the image areas 35 on the other surface of the substrate 17, the manufacture of the light guide plate 10 shown in FIG. 1 is completed.

  As described above, in forming the dot grooves 21, the output of the laser light 31 of the carbon dioxide laser processing machine is controlled by the density of the image data 25, so that the light guide plate 10 that emits light with uniform brightness in a predetermined area can be easily provided. Can be manufactured.

  As shown in FIG. 1, since the light source 11 is disposed on the entire surface of one end surface of the light guide plate 10, the portion corresponding to the bright portion 27 of the image data 25 shown in FIG. It becomes the whole surface. Further, a portion corresponding to the dark portion 28 is the entire other end surface of the substrate 17. Therefore, a predetermined area of the light guide plate 10 emits light uniformly only by entering light from one end face of the light guide plate 10. Therefore, it becomes easy to manufacture the light guide plate 10 that emits light uniformly and efficiently.

  Further, since the image area 35 of the image data 25 is formed, for example, in a grid pattern based on a resolution of 17 dpi, the number of uniformly arranged dot grooves 21 changes by variously changing the resolution. . Therefore, the light guide plate 10 capable of more efficient and uniform light emission can be manufactured. That is, since the light guide plate 10 of various types in a small lot can be performed at a low cost in a short time based only on the grayscale image data, it is an effective manufacturing method in the research and development field of the light guide plate.

  Further, the laser beam 31 is controlled at 16 output levels, and each of the average densities of the image area corresponds to each of the output levels. Therefore, control of the laser beam 31 is facilitated. Therefore, the processing of the laser beam 31 is accelerated, and the productivity of the light guide plate 10 is improved.

  FIG. 8 is a diagram showing image data for manufacturing a light guide plate according to another embodiment of the present invention. (1) shows a second embodiment, and (2) shows a third embodiment. This embodiment is shown.

  In the second and third embodiments, except for the shapes of the light guide plate and the light source, the configuration is the same as that of the light guide plate and the light source according to the first embodiment, and the manufacturing method is also the same. .

  First, referring to (1), in this embodiment, the same light sources 42a and 42b are arranged so that light is incident from both ends of a rectangular light guide plate (not shown). Yes. In the image data 41, rectangular planar areas 43a and 43b in the same range divided by two-dot chain lines corresponding to the predetermined areas of the light sources 42a and 42b are set.

  In the planar area 43a corresponding to the predetermined area of the light source 42a, the edge part on the light source 42a side is a bright part, and the part away from the bright part (the part where the two-dot chain line is located) is the dark part. It has become. Then, the shade changes gradually from the bright part to the dark part. On the other hand, the shading of the plane area 43b corresponding to the predetermined area of the light source 42b is set in the same manner as the plane area 43a with reference to the light source 42b.

  When the light guide plate is manufactured as described above using such image data 41, a dot groove having a greater depth is formed in a predetermined area of each of the light sources 42a and 42b as the distance from the light sources 42a and 42b increases. . Therefore, each of the predetermined areas emits scattered light uniformly, resulting in a wide light guide plate.

  Next, referring to (2), in this embodiment, the same light sources 46a to 46d are arranged so that light enters each of all end faces to a square light guide plate (not shown). ing. In the image data 45, triangular plane areas 47a to 47d of the same range divided by a two-dot chain line corresponding to each predetermined area of the light sources 46a to 46d are set.

  In the planar area 47a corresponding to the predetermined area of the light source 46a, the edge part on the light source 46a side is a bright part, and the part (the apex part of the planar area 47a) farthest from the bright part is the dark part. It has become. Then, the shade changes gradually from the bright part to the dark part. On the other hand, the shades of the planar areas 47b to 47d corresponding to the predetermined areas of the light sources 46b to 46d are set in the same manner as the planar area 47a with reference to the light sources 46b to 46d.

  When the light guide plate is manufactured as described above using such image data 45, a dot groove having a greater depth is formed as the distance from each of the light sources 46a to 46d increases in a predetermined area of each of the light sources 46a to 46d. . Therefore, each predetermined area emits scattered light uniformly.

  FIG. 9 is a view showing image data for manufacturing a light guide plate according to still another embodiment of the present invention. (1) shows the fourth embodiment, and (2) shows the first embodiment. 5 shows an embodiment of the present invention.

  In the fourth embodiment, except for the shapes of the light guide plate and the light source, the configuration is the same as that of the light guide plate and the light source according to the first embodiment, and the manufacturing method is also the same.

  First, referring to (1), in this embodiment, an annular light source 52 is arranged so that light is incident on the circular light guide plate (not shown) from the entire end face. In such a case, the image data 51 includes a fan-shaped planar area of the same range divided by the two-dot chain line, corresponding to each predetermined area of the portions 53a to 53d of the light source 52 divided into four equal parts by the two-dot chain line. 54a to 54d are set.

  In the planar area 54a corresponding to the predetermined area of the portion 53a of the light source 52, the arc-shaped edge portion on the side of the portion 53a is a bright portion, and the portion away from the bright portion (the apex of the planar area 54a). Part) is a dark part. Then, the shade changes gradually from the bright part to the dark part. On the other hand, the shades of the planar areas 54b to 54d corresponding to the predetermined areas of the portions 53b to 53d of the light source 52 are set in the same manner as the planar area 54a on the basis of each of the portions 53b to 53d.

  When the light guide plate is manufactured using the image data 51 as described above, the depth of the dot grooves increases as the distance from the portions 53a to 53d increases in each predetermined area of the portions 53a to 53d of the light source 52. It is formed. Therefore, each predetermined area emits scattered light uniformly.

  In this embodiment, a predetermined area is set by dividing the light source 52 into four equal parts, but the predetermined area (image data) is further subdivided, for example, by setting the predetermined area by dividing into six equal parts or eight equal parts. (Planar area) may be set.

  Next, referring to (2), in the fifth embodiment, the light source 56 is arranged such that light enters the entire surface of one end surface in the longitudinal direction with respect to a rectangular light guide plate made of a transparent acrylic resin (not shown). Is arranged. A plurality of areas are set by dividing the light guide plate into a plurality in the lateral direction. In the image data 55, a plurality of planes corresponding to each of the predetermined areas set for every other of the areas are set. Areas 57a and 57b are set. Further, in the adjacent areas 58a and 58b adjacent to these, the positions of the bright portions and the dark portions are set to be reversed with respect to the planar areas 57a and 57b.

  When the light guide plate is manufactured by the carbon dioxide laser processing machine using the image data 55 as in the first embodiment, the edge portions on the light source 56 side of the planar areas 57a and 57b are bright portions. The part (predetermined area) corresponding to each emits light uniformly similarly to the other embodiments described above. On the other hand, in the portion corresponding to each of the adjacent areas 58a and 58b where the edge portion on the light source 56 side is a dark portion, the upper portion is bright and the lower portion is dark. The light guide plate having such a striped light emission characteristic is used as an advertisement display, for example.

  In each of the above embodiments, a substrate made of a transparent acrylic resin is used for the light guide plate. However, a transparent resin such as polycarbonate may be used, and incident light is efficiently transmitted inside. Therefore, a substrate made of another material may be used as long as the inside is transparent.

  In each of the above embodiments, the light guide plate is formed in various shapes, but in addition to these, the light guide plate may be formed in other shapes such as an elliptical shape, a rhombus shape, or a curved diagram shape. It is sufficient to create image data.

  Furthermore, in each of the above embodiments, the bright portion of the image data is set to white and the dark portion is set to black. However, the difference is such that the density can be gradually changed in the portion between the bright portion and the dark portion. If there is, for example, the bright portion or the dark portion may be set to a predetermined gray level. Or you may set not only the combination of white and black but to change a density using other colors, such as red, for example.

  Further, in each of the above embodiments, the image area is set by dividing the image area into a grid based on a predetermined resolution (17 dpi). The image area may be set by dividing the image data into a plurality of shapes other than the above.

  Furthermore, in each of the above embodiments, an XY plotter type carbon dioxide laser processing machine is used. However, a so-called galvano scan type in which laser light is guided and processed by adjusting the irradiation angle of each mirror. You may use the carbon dioxide laser processing machine. In the case of the galvano scan type, dot grooves can be formed faster than in the XY plotter type. Alternatively, another type of laser processing machine may be used as long as it can form a dot groove by irradiating the light guide plate at a single point with an output corresponding to the average image density.

  Further, in each of the above-described embodiments, the laser beam is controlled at 16 levels of output level. However, as long as the image density in a predetermined range corresponds to each of the output levels, other plural numbers are used. It may be controlled at a stepwise output level. Alternatively, as long as the output is controlled to be large or small according to the magnitude of the density, for example, the output may be controlled to increase in proportion to the density.

  Furthermore, in each of the above-described embodiments, the dot grooves are formed in a rotationally symmetric shape similar to a truncated cone shape, but may be formed in a rotationally symmetric shape similar to a spherical crown shape. Alternatively, as long as it is a so-called dot shape (dot shape), it may be formed in another shape.

  Further, in the above first to fourth embodiments, the bright portion of the image data is set to the edge on the side corresponding to the end surface on the light source side, but the image data is reversed between the bright portion and the dark portion. It may be a gradation. In that case, it is necessary to control the output of the carbon dioxide laser processing machine to be small or large corresponding to the concentration.

  Furthermore, in the first embodiment, the entire front surface of the light guide plate is set as the predetermined area, but only a part of the front surface including only the central portion of the light guide plate is set as the predetermined area. Also good. In this case, for example, various light emission patterns can be set such that only a part of the predetermined area emits light uniformly and a part of the periphery is darkened, thereby expanding the usage of the light guide plate.

  Furthermore, in the first embodiment, light is incident from the entire surface of one end surface of the light guide plate. However, light is incident only from a part of the one end surface of the light guide plate corresponding to a predetermined area. It may be configured to.

  Next, experiments were performed to prove various effects of the dot grooves formed on the light guide plate according to the first embodiment. First, the reference Example D1 and the experimental method will be described.

  FIG. 10 is a schematic front view showing the light guide plate of Example D1, and shows an illuminance measurement area by a two-dot chain line.

  Referring to the drawing, a substrate made of a transparent acrylic resin (manufactured by Kanase, cast plate) having a width B of 300 mm, a height of H240 mm, and a thickness of 5 mm was used for the light guide plate 10 of Example D1. The image density GK in the image data was uniformly 100% black, the image resolution K was 17 dpi, the laser output P in the carbon dioxide laser processing machine was uniformly 60 w, and the height of the optical lens was +6 mm. That is, a dot groove was formed at a resolution of 17 dpi with a laser output P of 60 w on the entire light emitting surface of the light guide plate 10. When the height of the optical lens is +6 mm, the diameter of the formed dot groove is 0.7 mm.

  In addition, in order to verify the original performance of the light guide plate 10, no diffusion sheet is provided on the light emitting surface of the light guide plate 10 in all the following examples. Further, in order to verify the straightness of light from the light source 11 based on the light guide rate X described later, no reflective tape is attached to the end faces of the light guide plates 10 in all the following examples except Example D18.

  As an experimental method, the light-emitting surface of the light guide plate 10 was divided into measurement areas 1 to 15 each having a width of 60 mm and a height of 80 mm, the illuminance L was measured, and the light guide rate X was calculated. The light guide rate X is the average illuminance of each measurement area group having the same distance Y from the light source 11 and the average illuminance of each measurement area group adjacent to the light source 11 in the direction of the distance Y. It is the value divided. Accordingly, as the light guide rate X is higher, light reaches the adjacent measurement area group far from the light source 11 with less loss. That is, the straightness of light is high.

  Other equipment and equipment used in this experiment are carbon dioxide laser processing machine (made by SEI, Mercury 603 1520 400w), light source (LED device, made by Redscraft, LCP-NSRW-30 / 5), reflection sheet (Manufactured by Nitto Denko), illuminance measuring device (manufactured by Esco), and image data creation software (manufactured by Corel, CORELDRAW X3). In other examples described later, the same equipment and equipment as in Example D1 are used.

  The experimental results of Example D1 performed as described above are shown in the following table.

上記の表を参照して、実施例Ｄ１の全体の平均照度Ｌは４０２９ＬＵＸであり、全体の
平均導光率Ｘは７１．８％であった。又、光源からの距離Ｙ毎の測定エリア群の平均照度
は、６０ｍｍ地点で６８６９ＬＵＸ、１２０ｍｍ地点で５２６４ＬＵＸ、１８０ｍｍ地点で３６２７ＬＵＸ、２４０ｍｍ地点で２５４０ＬＵＸ、３００ｍｍ地点で１８２３ＬＵＸであった。この実施例Ｄ１の実験結果を基準として、ドット溝の条件を変更した他の実施例の実験結果を比較する。
１．ドット溝の深度と照度及び導光率との関係
実施例Ｄ２は、実施例Ｄ１におけるレーザー出力Ｐのみを一律に４０ｗに変更したものである。そして、実施例Ｄ３は実施例Ｄ１におけるレーザー出力Ｐのみを一律に８０ｗに変更したものである。従って、実施例Ｄ２のドット溝は実施例Ｄ１のドット溝より深度が小さくなり、実施例Ｄ３のドット溝は実施例Ｄ１のドット溝より深度が大きくなる。

With reference to said table | surface, the whole average illumination intensity L of Example D1 was 4029LUX, and the whole average light guide rate X was 71.8%. The average illuminance of the measurement area group for each distance Y from the light source was 6869 LUX at the 60 mm point, 5264 LUX at the 120 mm point, 3627 LUX at the 180 mm point, 2540 LUX at the 240 mm point, and 1823 LUX at the 300 mm point. Based on the experimental results of this Example D1, the experimental results of other examples in which the conditions of the dot grooves are changed are compared.
1. Relationship between Dot Groove Depth, Illuminance, and Light Guide Rate In Example D2, only the laser output P in Example D1 is uniformly changed to 40w. In Example D3, only the laser output P in Example D1 is uniformly changed to 80 w. Therefore, the dot groove of Example D2 has a smaller depth than the dot groove of Example D1, and the dot groove of Example D3 has a greater depth than the dot groove of Example D1.

  The illuminance and light guide rate of Examples D2 and D3 and Example D1 will be compared.

  FIG. 11 is a graph showing the average illuminance of the measurement area group for each distance Y from the light source of Examples D1 to D3, and FIG. 12 is a graph showing the overall average value of the experimental results of Examples D1 to D3. , (1) indicates the average illuminance, and (2) indicates the average light guide rate.

  First, referring to FIG. 11, when the distance Y is 60 mm to 180 mm, the illuminance L increases in the order of D3, D1, and D2, but when the distance Y exceeds 180 mm, the order is reversed. Yes. Then, referring to (1) of FIG. 12, the overall average illuminance has the highest value in Example D3 and the lowest value in Example D2. Therefore, it can be said that the higher the output of the laser beam, that is, the greater the depth of the dot groove, the higher the intensity of scattered light emitted. Referring to (2) of FIG. 12, the example D2 has the highest value in the overall average light guide rate. This is probably because less light is scattered by the dot grooves than in Examples D1 and D3.

Conclusion: Increasing the laser light output P (increasing the depth of the dot grooves) increases the average illuminance of the light guide plate. Further, when the output P of the laser light is increased, the light guide rate of the light guide plate is lowered.
2. Relationship between the number (interval) of dot grooves, illuminance, and light guide rate In Example D4, only the image resolution K in Example D1 is changed to 10 dpi. In Example D5, only the image resolution K in Example D1 is changed to 25 dpi. Therefore, the number of dot grooves in Example D4 is smaller than the number of dot grooves in Example D1, and the distance between each is increased. On the other hand, the number of dot grooves in Example D5 is larger than the number of dot grooves in Example D1, and the distance between each is smaller.

  The illuminance and light guide rate of Examples D4 and D5 and Example D1 will be compared.

  FIG. 13 is a graph showing the average illuminance of the measurement area group for each distance Y from the light sources of Examples D1, D4, and D5, and FIG. 14 shows the overall average value of the experimental results of Examples D1, D4, and D5. It is a graph, (1) shows an average illumination intensity, (2) shows an average light guide rate.

  First, referring to FIG. 13, when the distance Y is in the vicinity of 60 mm to 180 mm, the illuminance L increases in the order of D5, D1, and D4, but the order is finally reversed. Further, referring to (1) of FIG. 13, the overall average illuminance has the highest value in Example D5 and the lowest value in Example D4. Accordingly, it can be said that the smaller the interval between the dot grooves, that is, the greater the number of dot grooves, the higher the intensity of scattered light emitted. Referring to (2) of FIG. 13, D4 has the highest value in the overall average light guide rate. This is probably because less light is scattered by the dot grooves than in Examples D1 and D5.

Conclusion: Increasing the number of dot grooves (increasing image resolution K) increases the average illuminance of the light guide plate. Further, when the number of dot grooves is increased, the light guide rate of the light guide plate is lowered.
3. Relationship Between Dot Groove Diameter, Illuminance, and Light Guide Rate In Example D6, only the height of the optical lens in Example D1 is changed to a position of ± 0 mm. In Example D7, only the height of the optical lens in Example D1 is changed to the position of +12 mm. That is, with respect to the position of the optical lens of Example D1, Example D6 is changed to a position 6 mm lower and Example D7 is changed to a position 6 mm higher. Therefore, the dot groove diameter of Example D6 is smaller than the dot groove diameter (0.7 mm) of Example D1, and the dot groove diameter of Example D7 is larger than the dot groove diameter of Example D1. Specifically, the dot groove diameter of Example D6 is 0.3 mm, and the dot groove diameter of Example D7 is 1.0 mm.

  In Examples D1, D6, and D7, since the same laser output P is set, the depth of each dot groove is different. That is, since the laser output P has the same size, the depth of the dot groove having a large diameter is smaller than the depth of the dot groove having a small diameter.

  The illuminance and light guide rate of Examples D6 and D7 and Example D1 will be compared.

  FIG. 15 is a graph showing the average illuminance of the measurement area group for each distance Y from the light source of Examples D1, D6, and D7, and FIG. 16 shows the overall average value of the experimental results of Examples D1, D6, and D7. It is a graph, (1) shows an average illumination intensity, (2) shows an average light guide rate.

  First, referring to FIG. 15, the average illuminance L of the measurement area group for each distance Y increases in the order of D7, D1, and D6 at all points. Further, referring to (1) of FIG. 16, the overall average illuminance has the highest value in Example D7 and the lowest value in Example D6. Therefore, in consideration of the experimental results regarding the depth of the dot grooves described above, it can be said that the difference in average illuminance between Example D6 and Example D7 is further increased when converted to the same depth. Therefore, it can be said that the larger the dot groove diameter, the higher the intensity of scattered light emitted. Referring to (2) of FIG. 16, the example D7 has the highest value in the overall average light guide rate.

Conclusion: When the laser light output is the same, increasing the dot groove diameter increases both the average illuminance and the average light guide rate of the light guide plate. Therefore, if the position of the optical lens is adjusted so that the diameter of the dot groove is as large as possible, a light guide plate with high illuminance and high light guide rate can be obtained.
4). Relationship between laser output corresponding to each of various image shades, illuminance, and light guide rate In Examples D8 to D17, the image shade GK of Example D1 is changed, and the laser output P is changed correspondingly. doing. The image shading GK and laser output P of each of Examples D8 to D17 are shown in the following table.

更に、実施例Ｄ８〜Ｄ１７においては、実施例Ｄ１の光学レンズの高さを＋１０ｍｍの位置に変更している。具体的には、実施例Ｄ８〜Ｄ１７のドット溝の径は０．９ｍｍである。

Further, in Examples D8 to D17, the height of the optical lens of Example D1 is changed to a position of +10 mm. Specifically, the diameter of the dot grooves in Examples D8 to D17 is 0.9 mm.

  The overall average illuminance and average light guide rate of Examples D8 to D17 are compared.

  FIG. 17 is a graph showing the overall average value of the experimental results of Examples D8 to D17, in which (1) shows the average illuminance and (2) shows the average light guide rate.

  First, referring to (1), the average illuminance of each of the examples increases from the case where the image density GK is 10% (Example D8) as the value of the image density GK increases. It is the maximum when the density GK is 100% (Example D17). In other words, it can be said that the larger the laser output P, the higher the overall average illuminance is proved with the comparison of Examples D1 to D3. Next, referring to (2), as the value of the image density GK is smaller, that is, the laser output P is smaller, the overall average light guide ratio is larger. The relationship between the average light guide rates is also the same as the experimental results of Examples D1 to D3.

Conclusion: The average illuminance of the light guide plate increases as the image density GK of the image data increases (the laser output P increases). Moreover, the average light guide rate of the light guide plate decreases as the image density GK of the image data increases.
5. The uniformity of the scattered light emitted from the light emitting surface of the light guide plate The uniformity is a value obtained by dividing the minimum illuminance in all measurement areas by the maximum illuminance, and the uniformity of the scattered light can be confirmed.

  In Example D18, dot grooves were formed in the light guide plate using the image data shown in FIG. 5 under the conditions of the image density GK used in Examples D8 to D17 and the corresponding laser output P. About other conditions, although it is the same as Example D8-D17, in this Example, reflective tape (made by Nitto Denko) was stuck to all the end surfaces except the end surface by the side of the light source of a light-guide plate.

  The results of experiments performed using such Example D18 are shown in the following table.

上記の表を参照して、実施例Ｄ１８の均斉度は８７．９％であり、全体の平均照度Ｌは４３０５ＬＵＸである。

Referring to the table above, the degree of uniformity in Example D18 is 87.9%, and the overall average illuminance L is 4305 LUX.

  Here, in order to confirm the effectiveness of the uniformity and average illuminance in Example D18, a comparison with a conventional light guide plate was performed.

  The conventional light guide plate used in the comparative example uses a commercially available one having a silk print on the back surface, and the material, size, etc. are the same as in Example D18. Further, the other equipment and devices are the same as those in Example D18.

  Results of experiments conducted using such comparative examples are shown in the following table.

上記の表を参照して、比較例の均斉度は７５．１％であり、全体の平均照度Ｌは３９９５ＬＵＸである。従って、表３で示した実施例Ｄ１８の実験結果と比較すると、実施例Ｄ１８の均斉度８７．９％は十分に高い値であると言える。更には、実施例Ｄ１８の全体の平均照度は従来例の平均照度より高く、高品質な導光板であると言える。

Referring to the above table, the uniformity of the comparative example is 75.1%, and the overall average illuminance L is 3995LUX. Therefore, when compared with the experimental result of Example D18 shown in Table 3, it can be said that the uniformity 87.9% of Example D18 is a sufficiently high value. Furthermore, the average average illuminance of Example D18 is higher than the average illuminance of the conventional example, which can be said to be a high-quality light guide plate.

DESCRIPTION OF SYMBOLS 10 ... Light guide plate 17 ... Board | substrate 21 ... Dot groove 25, 41, 45, 51, 55 ... Image data 26, 43, 47, 54, 57 ... Planar area 27 ... Bright part 28 ... Dark part 31 ... Laser beam 35 ... Image Area The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (6)

A method of manufacturing a light guide plate, wherein the inside is made of at least a transparent substrate and emits light incident from a part of its end face as a uniform scattered light from a predetermined area on one side of the substrate,
Assuming a planar area corresponding to the size of the predetermined area of the substrate, the edge portion on the side corresponding to the end surface in the planar area is a bright portion with high brightness, and the maximum distance in the planar area from the bright portion The step of obtaining the image data in which the lightness is gradually changed in a portion between these as a dark portion having a low brightness as a remote portion,
Dividing the image data into a plurality of image areas and calculating an average image density of each image area;
A position corresponding to the center of each of the image areas on the other side of the substrate, with the output corresponding to each of the average image densities, using a laser beam whose output is controlled to be large or small according to the magnitude of the density. And a step of forming a dot groove on the light guide plate. The substrate has a rectangular shape in plan view in which the entire surface of the one surface is the predetermined area;
2. The part of the end surface is the entire surface of one end surface in the lateral direction of the substrate, and the portion corresponding to the dark portion in the image data is the entire surface of the other end surface in the lateral direction of the substrate. The manufacturing method of the light-guide plate of description.   The light guide plate manufacturing method according to claim 2, wherein the image area is obtained by dividing the image data into a lattice shape based on a predetermined resolution.   The light guide plate according to any one of claims 1 to 3, wherein the output of the laser light is controlled at a plurality of stepped output levels, and a predetermined range of image density corresponds to each of the output levels. Manufacturing method.   The said dot groove | channel is a manufacturing method of the light-guide plate in any one of Claims 1-4 which has a rotationally symmetric shape similar to a spherical crown shape or a truncated cone shape. A method of manufacturing a light guide plate, wherein the inside is made of at least a transparent substrate and emits light incident from a part of its end face as a uniform scattered light from a predetermined area on one side of the substrate,
Assuming a plane area corresponding to the size of the predetermined area of the substrate, the edge portion on the side corresponding to the end face in the plane area is a dark portion with low brightness, and the maximum distance in the plane area from the dark portion The step of making the distant portion a bright portion with high brightness, and acquiring image data in which the gradation gradually changes in the portion between these,
Dividing the image data into a plurality of image areas and calculating an average image density of each image area;
Using laser light whose output is controlled to be small or large according to the density, the output corresponding to each of the average image density and corresponding to the center of each of the image areas on the other surface of the substrate. And a step of forming a dot groove at a position.

Images