KR100413837B1 - The method of pattern making of light guide panel - Google Patents

Abstract

Disclosed are a surface light source device and a method of manufacturing the same. The present invention provides a light guide plate having a plurality of light guide pattern portions having a line width of at least 400 micrometers or more on a lower surface thereof so as to be diffused and scattered with uniform illuminance in each region by processing with a laser beam, and at least one provided on the side of the light guide plate. The above light emitting means and a reflecting plate provided below the light guide plate are included.

Description

Pattern forming method of light guide plate {The method of pattern making of light guide panel}

The present invention relates to a surface light source device, and more particularly to a surface light source device with an improved light guide plate and a manufacturing method thereof.

In general, a surface light source device used in a light receiving type flat panel display such as a liquid crystal display device or an illumination signboard is disclosed in Japanese Patent Application Laid-Open No. 60-216435, Korean Patent Application Nos. 93-11174, 94-26117, 94-33115, 94-26116.

In the surface light source device disclosed in the above-mentioned patents, partition walls are alternately installed inside a container having a closed space to form a meandering discharge space, and electrodes are provided at both ends of the discharge space, respectively. These discharges have a structure in which the phosphor layer formed in the discharge space is excited to emit light, or at least one lamp is provided on a side surface of the light guide plate to guide and diffuse light.

Figure 1 shows an example of a device using a light guide plate of the surface light source device.

As shown in the drawing, the surface light source device 10 includes a light guide plate 11, a reflecting plate 12 fixed to a lower surface of the light guide plate 11, and a diffusion plate 13 formed on an upper surface of the light guide plate 11. And light emitting means 14 fixed to at least one side of the light guide plate 11. As the light emitting means 14, a cold cathode tube or an LED lamp is used.

The light guide plate 11 includes a bead-shaped titanium oxide (TiO ₂ ) having a function of scattering and diffusing light incident on one surface of a transparent acrylic resin, and an ink including glass or acrylic, and a predetermined pattern. A plurality of reflective films 15 printed thereon are formed.

In the conventional surface light source device configured as described above, the light irradiated from the light emitting means 14 is irradiated to the light guide plate 11, and the light irradiated to the light guide plate 11 is formed by the reflecting plate 13 and the reflecting film 15. It has a relatively uniform illuminance at the site and is reflected toward the diffusion plate 13 side, and this light is diffused to the front surface through the diffusion plate 13.

However, when the reflective film 15 is formed on the light guide plate 11 by such a printing method, there are the following problems.

The manufacturing and printing process of the ink for forming the reflective film 15 is complicated, and there are many defective rates such as the printed reflective film 15 is dropped or smeared, so that the yield according to the formation of the film 15 is 70 to 80. It becomes low at% and cannot improve productivity. In addition, the light guide plate 11, which is not properly printed, cannot be reused after removing the reflective film 15, which is a factor of increasing manufacturing cost.

In order to solve the above problems, as shown in FIG. 2, in order to diffuse the light emitted from the light emitting means 24 provided on the side of the light guide plate 21 to each part of the light guide plate 21. A scratcher 22 has been formed on the bottom surface using a scraper. The cross-sectional shape of the scratch 22 is usually V-shaped.

However, the processing method of forming the scratch 22 on the lower surface of the light guide plate 21 as described above is made by a mechanical processing method, so that it is difficult to form a fine pattern, and uniform light diffusion and scattering are not achieved.

That is, since the narrow and deep scratches 22 are not easily formed on the lower surface of the light guide plate 21, fine patterns cannot be formed. When the thickness of the light guide plate 21 becomes thin, the depth and scatter of the scratches 22 are reduced. Depending on the degree, it is difficult to narrow the gap, so that a pattern may be seen. In addition, since the plurality of scratches 22 must be formed in sequence, the larger the light guide plate 21 is, the longer the unit processing time becomes and thus the productivity cannot be improved. Meanwhile, the line width of the processed scratch 22 is approximately 150 to 200 micrometers. When the line width is increased, deformation of the light guide plate 21 occurs due to frictional heat due to an increase in the friction area during processing.

The present invention is to solve the problems described above, it is possible to improve the productivity by forming a light guide pattern portion for scattering and diffusing the light on the lower surface of the light guide plate, it is possible to guide the light with a uniform brightness in front of the light guide plate. It is an object of the present invention to provide a surface light source device and a method of manufacturing the same.

1 is an exploded perspective view of a conventional surface light source device,

2 is a cross-sectional view showing a light guide plate of a conventional surface light source device;

3 is an exploded perspective view of the surface light source device according to the present invention;

4 is a cross-sectional view of a surface light source device according to the present invention;

5 to 14 is a perspective view showing a light guide pattern portion according to the present invention,

15 is a graph showing the light guiding efficiency for the line width according to the present invention.

<Brief description of symbols for the main parts of the drawings>

10,30 ... plane light source device 11,21,31 ... light guide plate

12,22 ... reflection plate 13 ... diffusion plate

14, 24, 34 ... Light-emitting means 15 ... Reflective film

31 ... scratch 50 ... light guide pattern

60 ... light diffusion unit

In order to achieve the above object, the surface light source device of the present invention,

A light guide plate formed on a lower surface of a plurality of light guide patterns having a line width of at least 400 micrometers by processing with a laser beam to diffuse and scatter light with uniform illuminance in each region;

At least one light emitting means provided on a side of the light guide plate; And

And a reflective plate installed under the light guide plate.

In addition, the shape of the light guide pattern portion is a dot consisting of grooves of a predetermined depth, a closed curve consisting of a groove of a circular or lattice, or a straight line consisting of continuous or intermittent grooves of a predetermined depth.

In addition, the light guide pattern portion is characterized in that the size is gradually increased by increasing the light diffusion and scattering rate as the distance from the light emitting means.

Furthermore, an upper surface of the light guide plate may further include a light diffusion part configured to diffuse light reflected from the light guide pattern part.

Method for manufacturing a surface light source device according to another aspect of the present invention,

A first step of forming a plurality of light guide patterns having a line width of at least 400 micrometers on a lower surface of the light guide plate, the grooves having a predetermined pattern formed by processing with a laser beam, so as to scatter and diffuse light guided from the side surface;

Attaching light emitting means to a side of the light guide plate; And

And a third step of installing a reflector for reflecting light guided from the light emitting means under the light guide plate.

In the first step,

When the laser beam is irradiated, the laser beam is scanned to prevent the light guide plate from being locally heated by the laser beam.

In addition, the first step is characterized by further comprising the step of forming the light diffusion portion by the scratch formed by the laser beam on the upper surface of the light guide plate.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

An embodiment of a surface light source device according to the present invention is shown in FIG. 3.

As shown in the drawing, the surface light source device 30 includes a light guide plate 31 having a plurality of light guide pattern portions 50 formed on a lower surface thereof in a predetermined pattern by a laser beam, and a bottom surface of the light guide plate 31. At least one reflector plate 32 and at least one side surface of the light guide plate 31 are provided to include light emitting means 34. The reflector 32 serves to reflect the light guided from the light emitting means 34 through the light guide plate 31 to the front side.

5 to 14 illustrate light guide patterns 50 formed by grooves processed by using a laser beam on a lower surface of the light guide plate 41.

Here, the same reference numerals as in the above-described drawings indicate the same members having the same function.

As shown in FIG. 5, the light guide pattern portion 50 is formed in the shape of a dot 51 processed using a laser beam, or a groove processed by the laser beam is circular as shown in FIGS. 6 and 7. It is formed by the independent closed curve which forms the 61 or the square 71, etc.

Another embodiment of the light guide pattern portion 50 is a groove on the grating 81 formed entirely on the bottom surface of the light guide plate 31 as shown in FIG. 8, and a circular shape provided inside the grating 81. 9 to 12, the light guide pattern portion 50 includes a plurality of circles 91 having grooves processed by a laser beam having the same center and having different diameters. ), Or a plurality of straight grooves are formed in a pattern of a circle 101 or a square 111 and a pattern on a unit grid 121.

In addition, as illustrated in FIG. 13 or 14, the light guide pattern part 50 may be formed as a groove forming an intermittent square 131 having a constant pitch in the vertical axis direction with respect to the incident direction of light incident on the light guide plate 31. Alternatively, grooves forming one continuous square 141 along one side of the light guide plate 41 may be formed in a pattern spaced apart from each other by a predetermined interval.

The light guide pattern unit 50 is not limited to the above-described embodiment and may be any structure that can reflect, diffuse, and scatter the light irradiated from the lamp to the front side. In the above-described embodiment, the light guide pattern portion 50 formed of a closed curve formed by dots and grooves, or an intermittent or continuous straight groove is gradually larger in size as it moves away from the light emitting means 34. It is preferable that the amount is gradually increased to prevent a decrease in luminance caused by moving away from the light emitting means 34. In addition, if the length or width of the dot or groove is changed, the scattering characteristics of the light guide amount can be adjusted to obtain uniform luminance.

In addition, as shown in FIG. 4, the light diffusing part 60 is formed on the upper surface of the light guide plate 31 on which the light guide pattern part 50 is formed. The minute scratches constituting the light diffusing portion 60 may be formed differently depending on the site so that the uniform density of light may be diffused on the entire surface of the light guide plate 31.

In addition, the light diffusion part may not be formed on the upper surface of the light guide plate 31, and a separate diffusion plate may be installed, and a diffusion plate may be further installed on the upper surface of the light guide plate 31 on which the light diffusion part 60 is formed. to be.

The line width of the light guide pattern portion 50 formed on the lower surface of the light guide plate 31 as described above is determined by the following experimental values.

The light guide plate used in a small size, for example, a flat panel display device of 15 inches or less, has a thickness of about 3 millimeters or less, and minimizes variations in thickness due to shrinkage characteristics of the material by injection molding so as to have a predetermined thermal stress.

On the other hand, a light guide plate used in a large-sized flat panel display device, such as a 15 inch or more device, has a thickness of at least 4 millimeters or more, and at least one lamp having at least one light emitting means is installed on both sides of the light guide plate to provide light to the light guide plate. It is a structure to investigate. Such a light guide plate is not injection molded, but is formed by forming a disc by casting or extrusion method of filling a sol-like resin between a plurality of closed glass plates and then cooling it, and then cutting the plate to a desired size.

Such an enlarged flat panel display device has an effective screen area of about 200 x 300 millimeters or more. In this case, the light guide plate corresponds to the size thereof, so that the area is divided into a plurality of mosaics and processed in a mosaic manner. As a result, productivity is reduced and physical properties such as dark areas or curved lines are generated at each boundary, thereby deteriorating the appearance characteristics. Therefore, it is necessary to form the light guide pattern portion 50 by the minimum processing, for example, two or less laser processing.

Although the position of the galvanometer is fixed with respect to the laser oscillation part during laser processing, the magnification increases geometrically when the focal length increases, so the processing area of the light guide plate is proportional to the focal length, and the beam hardness of the laser increases as the focal length increases. Will increase. Therefore, in order to increase the processing area, the focal length must be long, and at the same time, since the beam diameter of the laser is increased, the output of the laser must be increased in proportion to obtain the same laser density.

FIG. 15 is a graph illustrating light guiding efficiency according to line width change of the light guiding pattern unit 50 for each output of each laser device.

The X axis shows the line width of the light guide pattern portion 50, and the Y axis shows the light guide efficiency. Here, the light guiding efficiency is divided into nine equal parts of a light guide plate applied to a 15-inch flat panel display device having a thickness of 4 millimeters, the luminance of nine center points of each divided surface is measured, and then the luminance uniformity satisfies 70% or more. The relative luminance I is shown as the relative luminance I with the average luminance of as the reference I ₀ and the highest luminance according to the line width change of the pattern for each laser output.

Referring to the graph, in the case of a laser device having a power of 10 W (curve A), the light guiding efficiency of the light guiding pattern part 50 shows a good light guiding efficiency of nearly 1.0 while the line width is 90 to 300 micrometers, When it becomes 300 micrometers or more, it turns out that the characteristic which scatters light on a pattern starts to fall, and light guide efficiency falls rapidly.

This is because the energy density decreases as the laser beam diameter increases as the focal length increases with respect to the light guide plate 31, thereby increasing only the line width while decreasing the depth of the unevenness causing light scattering on the light guide plate 31. to be. Therefore, in the case of a laser device having an output of 10 W, it is possible to form the light guide pattern portion 50 with a line width of up to 300 micrometers, and the area to be processed will be approximately 100 x 100 millimeters. On the other hand, in the case of having a line width of about 90 micrometers, the size of 60 × 60 mm becomes the maximum processing area, and thus the size of the light guide plate 31 to which the laser device having the output of 10 W is applied is 100 × 100 mm or less. .

Next, in the case of a laser device having an output of 20 W (B curve), the light guide efficiency of the light guide pattern portion 50 was nearly 1 in the range of approximately 400 to 600 micrometers. When the line width of the light guide pattern portion 50 is 400 micrometers, the processable area is 200 × 200 millimeters, which makes it possible to apply to an enlarged flat panel display device.

In the case of a laser device having a power of 30 W (C curve), the light guiding efficiency of the light guide pattern portion 50 was within the range of 600 to 1000 micrometers. It seems to decrease slowly.

As a result, the light guide efficiency according to the line width of the light guide pattern portion 50 of the light guide plate 31 is measured for each output of the laser device, and thus the light guide pattern portion 50 for application to an enlarged flat panel display device having a thickness of 4 mm or more. ) Should have a line width of 400 micrometers or more, and the laser device output should be approximately 20 W or more.

The line width of the light guide pattern portion 50 should be larger than 400 micrometers because the data processing speed of the control device for controlling the laser oscillation and galvanometer when the light guide pattern portion 50 is formed by laser is constant. This is because the processing time is shortened as the data capacity of the light guide pattern portion 50 is smaller.

Accordingly, as the line width of the light guide pattern portion 50 increases, the pitch of the pattern portion 50 for obtaining uniform luminance increases, and the number of the pattern portion 50 per unit area or the data of the pattern portion 50 per unit area is increased. The larger the line width, the shorter the machining time.

The manufacturing method of the surface light source device 30 configured as described above is as follows.

A first step of forming a plurality of light guide patterns 50 formed of grooves of a predetermined pattern formed by using a predetermined laser beam on a lower surface and scattering and diffusing light guided to the side; and a side surface of the light guide plate 31 A second step of attaching a light emitting means 34, such as a cold cathode ray tube or an LED, to the light emitting plate 34, and a reflecting plate 32 for reflecting light guided from the light emitting means 34 to the bottom surface of the light guide plate 41. Includes three steps.

The first step of forming the light guide pattern portion 50 using a laser beam on one surface of the light guide plate 41 is driven according to the coordinate value of the pattern and the predetermined light guide pattern portion formation region and frequency through the control unit of the laser generation system. The laser beam outputted from the laser driver by the pulse signal synchronized with the optical driver including the galvanometer is scanned by the light guide plate 31.

At this time, since it recognizes the starting point and the end point of the light guide pattern portion 50 with respect to the origin coordinates and the position coordinate values for the shape therebetween, the linear processing time is shorter than that of the curve. Since the formation of the light guide pattern portion 50 consisting of a continuous straight line rather than a straight line is advantageous in terms of production efficiency, the shape of the light guide pattern portion 50 may be said to be preferably a continuous straight groove.

On the other hand, the laser beam is an infrared laser beam having a wavelength of 1 micrometer, preferably 10.6 micrometers or more in the infrared region capable of absorbing heat of the transparent acrylic resin. In the formation of the light guide pattern portion 50 by the laser beam, it is preferable to scan the laser beam in order to prevent the light guide plate 31 from being locally heated.

If the scanning speed is increased to reduce the local heating of the light guide plate 31 by the laser beam, the local heating temperature is lowered and the output of the laser beam should be increased to compensate for this.

As described above, since the shape of the light guide pattern portion 50 by scanning the laser beam has been described in the structure of the light guide plate 31, the description thereof will not be repeated.

On the other hand, the first step further comprises the step of forming a light diffusion unit 60 to diffuse the light by forming a scratch on the upper surface of the light guide plate 31 by a laser beam. The light diffusing portion 60 forming step is performed by forming a very fine scratch on the beam diameter of the laser beam.

The method of manufacturing the surface light source device may further include a fourth step of installing a separate diffuser plate on an upper surface of the light guide plate 31.

Referring to the surface light source device configured as described above and the operational effects of the manufacturing method thereof are as follows.

In the surface light source device 30 configured as described above, as the light emitting means 34 emits light, the light irradiated toward the light guide plate 31 guides the light guide plate 31 made of acrylic. The light irradiated to the lower surface of the light guide plate 31 among the non-parallel light is scattered and diffused by the reflecting plate 32 and the light guide pattern portion 50 and irradiated to the front surface of the light guide plate 31.

As described above, the scattering and diffusion of light by the light guide pattern portion 50 is reflected to the front surface by a boundary surface of a groove formed of a lattice shape, a closed curve, or the like, or a boundary surface of a groove formed of an intermittent or continuous straight line. Since the groove is processed using a laser beam, its interface is smooth near the mirror surface. Therefore, the reflection efficiency of light can be improved.

As described above, the light reflected and diffused to the upper surface side of the light guide plate 31 by the reflecting plate 32 and the light guide pattern portion 50 is scattered by the scratches forming the light diffuser 60 formed on the upper surface of the light guide plate 31. And diffused and irradiated.

As described above, the surface light source device and its manufacturing method according to the present invention can significantly reduce the defects caused by the formation of the pattern using the ink on the lower surface of the light guide plate as in the prior art can improve the productivity, the light guide pattern The width of the groove forming the portion can be arbitrarily adjusted, thereby reducing light loss due to scattering and diffusion of light.

Although the present invention has been described with reference to the embodiments illustrated in the drawings, this is merely exemplary and may be modified by those skilled in the art within the technical scope of the present invention.

In addition, the invention can be used as a surface light source used in a light receiving type image display apparatus such as a liquid crystal display element by using the above discharge.

Claims (10)

delete delete delete delete delete delete delete In the pattern formation method of the light guide plate of the surface light source device used as a back light source, Infrared laser driver by a pulse signal synchronized to the optical drive unit including a galvanometer driven according to the coordinate value of the pattern and the pattern formation region and frequency through the control unit of the infrared laser generation system on the lower surface of the light guide plate formed of transparent acrylic resin Scanning an infrared laser beam output from the bottom surface of the light guide plate; And forming the plurality of light guide patterns on the bottom surface of the light guide plate by the infrared laser beam to prevent the heating of the light guide plate locally by scanning the infrared laser beam. delete In the pattern formation method of the light guide plate of the surface light source device used as a back light source, Infrared laser driver by a pulse signal synchronized to the optical drive unit including a galvanometer driven according to the coordinate value of the pattern and the pattern formation region and frequency through the control unit of the infrared laser generation system on the lower surface of the light guide plate formed of transparent acrylic resin Scanning an infrared laser beam output from the bottom surface of the light guide plate; When the plurality of light guide patterns are formed on the bottom surface of the light guide plate using the infrared laser beam, scanning the infrared laser beam to prevent the light guide plate from being locally heated; Forming a light diffusion part on an upper surface of the light guide plate to diffuse light from a pattern formed on a lower surface of the light guide plate by an infrared laser; Pattern forming method of the light guide plate of the surface light source device consisting of.