KR101240780B1 - LED face lighting device - Google Patents

Abstract

The present invention relates to an LED surface lighting apparatus using a light guide plate on which a plurality of patterns are formed. The LED surface lighting apparatus according to the present invention includes a light guide plate having a plurality of LED light sources and a plurality of patterns arranged in a lattice structure. The shapes of the plurality of patterns may be square pyramids, square pyramids, spherical shapes, and are formed intaglio on the light guide plate.
According to the present invention, the pattern is formed on the light guide plate so that the light from the LED light source is uniformly diffused, so that the efficiency of the LED surface lighting device is good and the pattern is formed using a mold, so that the production of the light guide plate is easy.

Description

LED lighting device {LED face lighting device}

The present invention relates to an LED surface lighting apparatus using a light guide plate having a pattern. More specifically, a plurality of LED light sources and a plurality of patterns having one of square pyramids, square pyramids, and spherical shapes on the incident surface are arranged in a lattice structure. By including the engraved light guide plate, the light incident from the LED light source is uniformly distributed, so that there is no hot spot and the illumination is uniform.

LED is widely used for home and indoor lighting. Lighting using LEDs has less energy consumption than existing fluorescent lamps, which saves electricity costs and is environmentally friendly. In addition, LED-based lighting has a long life, which can reduce maintenance costs. For this reason, research, development and commercialization are underway as a lighting device that replaces existing fluorescent and incandescent lighting.

LED lighting is mainly used as a bulb type, but a plurality of such LEDs are used to enlarge the surface lighting. In order to use an LED light source for surface lighting, a light guide panel (LGP) for dispersing light is used. Conventional LED surface lighting has been developed in an edge manner in which a light source is arranged at the edge of the light guide plate to diffuse light by the diffuser plate and the light guide plate. However, due to the edge characteristics, there is a technical limitation to use it as a direct lighting device due to low illuminance and light efficiency of the light source.

In order to solve this problem, a direct lighting method in which an LED light source is arranged in a lattice structure on a PCB board and diffuses light by directly passing through a light guide plate has appeared, but an LED surface lighting apparatus using a conventional light guide plate has a plurality of LED lights. This uniform dispersion does not occur, resulting in hot spots and uneven illumination. As shown in FIG. 1, a conventional LED surface lighting apparatus using a light guide plate has a dark portion (D) where light does not pass when the LED light passes through the light guide plate, and a smaller distance from the LED light source to eliminate the dark portion (D). Should be placed. As a result, manufacturing cost increases and there is a problem in that the LED light source cannot be efficiently used.

Therefore, it is necessary to develop a surface light using an LED light source that evenly distributes the light of the LED light source and does not generate hot spots or dark areas, and has uniform illumination and stable brightness.

It is an object of the present invention to provide an LED surface lighting apparatus with uniform illuminance without hot spots or dark areas.

In addition, it is to provide an LED surface lighting device that can be formed at a low cost and simple pattern of the light guide plate.

In order to achieve the above object, the LED surface lighting apparatus according to the embodiment of the present invention includes a light guide plate having a plurality of LED light source, the incident surface and the exit surface. The plurality of LED light sources are arranged in a lattice structure. Light is incident from the plurality of LED light sources through the incident surface of the light guide plate. A plurality of patterns are formed in a lattice structure on the incident surface to diffuse the incident light to make the illumination of the irradiation surface uniform. An exit surface of the light guide plate emits incident light.

In the LED surface lighting apparatus according to the embodiment of the present invention, a plurality of patterns are formed in an intaglio, and are formed in one of a square pyramid, a square pyramid, and a spherical shape.

LED surface lighting apparatus according to an embodiment of the present invention adjusts the uniformity of the illuminance of the irradiation surface by adjusting the interval of the plurality of patterns.

In the LED surface lighting apparatus according to the embodiment of the present invention, the smaller the interval between the plurality of patterns, the higher the uniformity of illuminance of the irradiation surface.

In the LED surface lighting apparatus according to the embodiment of the present invention, the plurality of LED light sources and the light guide plate may be separated by at least 30 mm.

LED surface lighting apparatus according to an embodiment of the present invention may further include a housing for receiving the LED light source and the light guide plate.

The LED surface lighting apparatus of the present invention can form a pattern on the light guide plate by a simple method.

In the LED surface lighting apparatus of the present invention, a pattern is formed on the light guide plate so that the light of the LED light source is uniformly diffused so that the illuminance is uniform.

LED surface lighting apparatus of the present invention can save energy by using the LED light source and is easy to maintain and repair.

1 is a view showing a conventional direct system surface lighting.
2A and 2B are diagrams showing the refraction of light according to the convex lens and the concave lens.
3A to 3D are diagrams illustrating a light guide plate having a square pyramid-shaped pattern and a square pyramid-shaped pattern according to an embodiment of the present invention.
4 is a view showing the diffusion of light when the LED light passes through the light guide plate formed with a square pyramid pattern according to an embodiment of the present invention.
5A to 5D are diagrams illustrating a light guide plate on which a square pyramid-shaped pattern and a square pyramid-shaped pattern according to an embodiment of the present invention are formed.
FIG. 6 is a view illustrating the diffusion of light when LED light passes through a light guide plate having a square pyramid-shaped pattern according to another embodiment of the present invention.
7A to 7D are diagrams illustrating a light guide plate on which a spherical pattern and a spherical pattern according to another embodiment of the present invention are formed.
FIG. 8 is a diagram illustrating the diffusion of light when LED light passes through a light guide plate having a spherical pattern according to another exemplary embodiment of the present invention.
9A to 9D are diagrams illustrating illuminance distributions of a conventional light guide plate and a lighting device using the light guide plate according to the embodiment of the present invention.
10 (a) and 10 (b) are diagrams showing the uniformity of roughness according to the spacing of patterns.
It is a figure which shows the correlation between the spacing of a pattern, and the uniformity of roughness.
12 is a view showing a surface lighting apparatus according to an embodiment of the present invention.
13A to 13D are diagrams illustrating a hot spot generation degree according to a distance between a plurality of LED light sources and a light guide plate.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that, in the drawings, the same components are denoted by the same reference symbols as possible. Further, the detailed description of known functions and configurations that may obscure the gist of the present invention will be omitted. For the same reason, some of the components in the drawings are exaggerated, omitted, or schematically illustrated.

2A and 2B are diagrams showing the refraction of light according to the convex lens and the concave lens.

LEDs have a higher straightness and less light diffusion than incandescent and fluorescent lamps. Therefore, the LED lighting device appears dark when it is out of the center of the LED light source, and the illuminance on the irradiation surface is not constant. In order to solve this problem, the present invention uses the property that the light is refracted differently according to the shape of the incident surface.

As shown in FIG. 2A, when the light passes through the convex lens, the light is concentrated toward the center of the lens because the light is refracted toward the thick side, that is, the narrow area is illuminated. On the other hand, as shown in FIG. 2B, when the light passes through the concave lens, the lens is refracted toward the thick side and light is diffused. Therefore, the light shines in a large area.

Therefore, in order to diffuse the light, a concave pattern must be formed in the light guide plate, and the degree of light diffusion varies depending on the shape of the pattern. In the present invention, the pattern of square pyramid, square pyramid and spherical shape is derived in consideration of the uniformity of illuminance in which the light guide plate uniformly diffuses light, the design and processability of the light guide plate.

(A) to (d) is a view showing a light guide plate formed with a square pyramid-shaped pattern and a square pyramid-shaped pattern according to an embodiment of the present invention, Figure 4 is a square pyramid shape according to the embodiment of the present invention the LED light It is a figure which shows the spread of the light at the time of passing through the light guide plate in which the pattern of the is formed.

As shown in FIGS. 3A to 3C, a square pyramidal pattern is engraved on the light guide plate. Square pyramid is 1mm long and 0.5mm high. When the height of the pattern is increased, the pattern processing of the light guide plate is not easy. Therefore, in the present embodiment, the height of the pattern is set to 0.5 mm in consideration of workability. A plurality of square pyramidal patterns are formed in a lattice structure at 0.25 mm intervals. 3 (d) shows a plurality of square pyramid-shaped patterns arranged in a lattice structure on the light guide plate. In order to improve the understanding of the drawings, the patterns and the spacing of the patterns are exaggerated than actual.

As shown in FIG. 4, the light emitted from the LED light source is incident on the incident surface 210. The light incident through the pattern is refracted by the pattern, passes through the light guide plate 200, and the light emitted through the exit surface 220 of the light guide plate 200 is uniformly diffused without formation of a dark portion.

Specifically, look at assuming that the light emitted from the LED light source is 60 °. Equation (1) represents Snell's law that determines the path of light.

nsin θ = n'sin θ '... ... ... Formula (1)

Light emitted from the LED light source is incident through the inclined surface of the square pyramid-shaped pattern of the light guide plate 200. When the inclination angle of the inclined surface of the pattern is 45 degrees, the incident angle θ of light incident on the inclined surface becomes about 15 degrees based on a normal perpendicular to the inclined surface. Refractive angle θ 'generated upon incidence into the light guide plate with respect to the incident angle θ (= 15 °) is about 10 °. When the light exits through the exit surface 220 of the light guide plate 200, the incident angle θ ″ in which light is incident on the exit surface 220 may be about 35 °. In this case, when the light exits the exit surface 220. When the angle of refraction is calculated, the angle of refraction θ '"is about 60 degrees. This value is compared with the angle of refraction by the light guide plate in which the pattern shown in FIG. 1 is not formed.

As shown in FIG. 1, light emitted from the LED light source is incident through the incident surface 110 of the light guide plate 100. At this time, when the incidence angle θ is 30 °, the refraction angle θ 'generated upon incidence into the light guide plate 100 is about 19 °. When the light exits through the exit surface 120 of the light guide plate 100, the incident angle θ " at which light enters the exit surface 120 becomes about 19 °, and at this time, the refraction angle when the light exits the exit surface 120 When the refraction angle θ '"is about 30 degrees, the refraction angle is smaller than when passing through the light guide plate on which the pattern is formed. That is, when the light is diffused through the light guide plate having the square pyramid-shaped pattern according to the present invention, the angle of refraction, that is, the emission angle of the light becomes large, and no dark portion is generated. As a result, the light is diffused more uniformly.

5 (a) to (d) is a view showing a light guide plate formed with a square pyramid-shaped pattern and a square pyramid-shaped pattern according to an embodiment of the present invention, Figure 6 is a LED light according to an embodiment of the present invention It is a figure which shows the spread of the light when passing through the light guide plate in which the square pyramid-shaped pattern was formed.

As shown in FIGS. 5A to 5C, a square pyramid-shaped pattern is engraved on the light guide plate. The square pyramid has 1mm side length and 0.4mm length side. The height between the top and bottom is 0.3mm. The plurality of square pyramid-shaped patterns are formed in a lattice structure at 0.25 mm intervals. FIG. 5 (d) shows that a square pyramid-shaped pattern is arranged in a lattice structure on the light guide plate.

As shown in FIG. 6, the light emitted from the LED light source is refracted and diffused at a larger angle by the pattern of the light guide plate 200, and the LED surface lighting apparatus has uniform illumination without forming dark parts. The calculation of the specific radiation angle is omitted because it is similar to the description in FIG. 4 described above.

7A to 7D are diagrams illustrating a light guide plate on which a spherical pattern and a spherical pattern are formed according to an embodiment of the present invention, and FIG. 8 is a spherical shape according to an embodiment of the present invention. It is a figure which shows the spread of the light at the time of passing through the light guide plate in which the pattern of the is formed.

As shown in FIGS. 7A to 7C, spherical patterns are engraved on the light guide plate. The sphere is part of a sphere with a radius of 0.05 mm and is formed with a height of 0.017 mm. Each sphere is formed in a lattice structure such that the spacing of the centers of the spheres is 0.125. FIG. 7D illustrates that the spherical pattern is arranged on the light guide plate 200.

As shown in FIG. 8, the light emitted from the LED light source is refracted and diffused at a larger angle by the pattern of the light guide plate 200, and the LED surface lighting apparatus has uniform illumination without forming dark parts. The calculation of the specific radiation angle is omitted because it is similar to the description in FIG. 4 described above.

Next, a method of forming a pattern on the light guide plate 200 will be described. As the material of the light guide plate 200, PMMA (polymethylmethacrylate), which is a transparent acrylic resin, is mainly used. PMMA has high mechanical strength and is not easily broken or deformed, and is light and chemically resistant. In addition, it is transparent and has a high visible light transmittance, which is preferable as a material of the light guide plate 200. The refractive index of PMMA is usually 1.49 ~ 1.62, and the light transmittance is 88 ~ 93. In this embodiment, the thickness of the light guide plate is 5 to 7 mm, preferably 6 mm.

The pattern of the light guide plate 200 may be formed through a mold. The light guide plate in which the pattern is formed by a mold is called a printless LGP. The printless light guide plate is manufactured using a metal mold or a metal mold on which a pattern is processed. The metal plate used at this time is called a stamper. The metal plate with a pattern can be attached to the metal mold | die of a light guide plate, and can be used. In addition, a pattern may be formed on one surface of the mold through chemical etching, or may be processed by laser to form a pattern. By forming the pattern of the light guide plate into a mold, the pattern can be formed more simply and inexpensively, thereby making the surface lighting device simple and inexpensive.

9A to 9D are diagrams illustrating illuminance distributions of a conventional light guide plate and a lighting device using the light guide plate according to the embodiment of the present invention.

As shown in (a) of FIG. 9, when the illuminance of the lighting apparatus using the light guide plate having no pattern is measured, it can be seen that a hot spot occurs in the portion where the LED light source is disposed and the illuminance distribution is uneven. In addition, it can be seen that the light is not diffused widely and the area where light shines is also narrow. On the other hand, as shown in (b) to (d) of Figure 9, when measuring the illuminance of the lighting device using the light guide plate having a pattern, the light is diffused does not produce a hot spot, because the radiation angle is large in a large area Uniform illuminance distribution In particular, it can be seen that the light guide plate using the spherical pattern is most uniformly distributed with high illuminance.

On the other hand, in the LED surface lighting apparatus according to the present invention, the uniformity of illuminance varies according to the interval of the pattern formed on the light guide plate.

10A and 10B are diagrams showing uniformity of illuminance according to the spacing of patterns, and FIG. 11 is a diagram showing a correlation between the spacing of patterns and uniformity of illuminance.

Uniformity of illuminance indicates the degree of uniformity of illuminance distribution on the irradiated surface. When the highest illuminance on the irradiated surface is L _max and the lowest illuminance is L _min , the uniformity of illuminance is expressed as in Equation (2).

……… 식(2)

... ... ... Equation (2)

As shown in FIG. 10, it can be seen that as the spacing of the patterns becomes smaller, the radiation angle becomes wider, so that the light is diffused more and the illuminance becomes uniform.

11 shows the correlation between the spacing of the patterns and the uniformity of the roughness. The smaller the pattern spacing, the higher the uniformity of illuminance. As the spacing of the patterns becomes narrower, the radiation angle of the light incident on the light guide plate becomes larger and the uniformity of illuminance becomes high, thereby making the illuminance of the LED surface illumination device uniform. However, as the spacing of the patterns becomes narrower, the pattern formation becomes more difficult, and the unit cost of the light guide plate is increased. In this case, the distance between the centers of the spheres was 0.125 mm.

Since the LED surface lighting apparatus according to the present invention diffuses light at a wide radiation angle, it is possible to widen the interval of the LED light source, thereby reducing the number of LED light sources required to manufacture LED surface lighting apparatus at a lower cost. Can be.

The following table shows the roughness measurement results. The surface lighting device used a length and width of 0.6m × 0.6m, and measured nine points of the square section of 6m × 6m below the lighting device. The distance from the illuminating device to the measurement surface was 1 m and 2 m 10 m.

Table 1 shows the results when the distance from the illuminating device to the measurement surface is 1 m. The illuminance at the center is 1200 lux and the minimum illuminance is 2.24 lux. Average roughness is 83.5 lux.

[Table 1]

Table 2 shows the results when the distance from the illumination device to the measurement surface is 2 m. The central illuminance is 300 lux and the minimum illuminance is 8.64 lux. Average roughness is 69.6 lux.

[Table 2]

Table 3 shows the results when the distance from the illumination device to the measurement surface is 10 m. The central illuminance is 12 lux and the minimum illuminance is 8.53 lux. Average roughness is 10.6 lux.

[Table 3]

12 is a view showing a surface lighting apparatus according to an embodiment of the present invention, Figure 13 (a) to (d) is a view showing the degree of hot spots according to the separation distance between the plurality of LED light source and the light guide plate.

As shown in FIG. 12, the LED surface lighting apparatus according to the present invention may further include a housing accommodating a plurality of LED light sources and a light guide plate. The housing arranges the plurality of LED light sources in a lattice structure, and positions the light guide plate at a distance spaced apart from the plurality of LED light sources. The distance between the LED light source and the light guide plate is adjusted by adjusting the light guide plate fixing position in the housing. If the distance between the LED light source and the light guide plate is too close, the hot spot phenomenon becomes severe, and therefore, the distance between the LED light source and the light guide plate should be spaced at a predetermined interval.

As shown in FIG. 13, when the distance between the LED light source and the light guide plate is 5 mm, the hot spot is most severe, and as the distance between the LED light source and the light guide plate increases, the hot spot phenomenon is alleviated. That is, even when the LED light is diffused through the pattern formed in the light guide plate, it can be seen that the diffusion effect of the pattern is not good when the distance between the LED light source and the light guide plate is close. In the LED surface lighting apparatus according to the present invention, the degree of hot spot occurrence of the surface lighting apparatus was confirmed by varying the separation distance between the LED light source and the light guide plate, and when the distance between the LED light source and the light guide plate is at least 30 mm or more, the hot spot by the pattern is separated. A relaxed uniform roughness could be obtained.

The LED light source is energy efficient and is expected to be enormously marketable as a light source that can replace incandescent lamps and fluorescent lamps. It is reported that if 13% of all lamps are replaced by LED light sources, 7% of crude oil consumption will be reduced, and the annual energy saving effect will be great through the development of LED lighting devices.

It should be noted that the embodiments of the present invention disclosed in the present specification and drawings are only illustrative of the present invention in order to facilitate description of the present invention and to facilitate understanding of the present invention and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

100: conventional light guide plate 200: patterned light guide plate
110, 210: entrance plane 120, 220: exit plane

Claims (6)

A plurality of LED light sources arranged in a lattice structure;
Light incident from the plurality of LED light sources is diffused and the incident light is diffused to uniform the illuminance of the irradiated surface, and a plurality of patterns formed in a square pyramid are engraved in a lattice structure, and an exit surface for emitting light The light guide plate having a; And
And arranging the plurality of LED light sources in a lattice structure and placing the light guide plate at a distance of at least 30 mm from the plurality of LED light sources.
The plurality of patterns formed on the incident surface is formed by a metal mold, LED surface lighting device. delete The method of claim 1,
LED surface illumination apparatus characterized by adjusting the uniformity of the illuminance of the irradiation surface by adjusting the interval of the plurality of patterns. The method of claim 3,
LED surface illumination device characterized in that the uniformity of the illuminance of the irradiation surface increases as the interval between the plurality of patterns is reduced. delete delete

Images