KR20090058900A - Surface light source apparatus - Google Patents

Abstract

A surface light source device is provided to uniformize distribution of quantity of light applied to a light guide plate by forming a light reflection structure in a wavy shape or cross shape and reduce production cost. A surface light source device comprises a light guide plate, a light source section, and a light reflection structure(113). The light source section is arranged in one side of the light guide plate. The light reflection structure is formed in a rear side of the light guide plate. The light reflection structure is formed with a mirror surface without concavo-convex so as for reflected light to have predetermined orientation.

Description

Surface light source apparatus

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface light source device, and more particularly, to a surface light source device used as a light guide plate backlight which is a rear light source in an image display device such as a liquid crystal display device and an emergency exit induction device.

Recently, due to the rapid development of technology in the semiconductor industry, display products with smaller size, lighter weight, and improved performance are being produced. Cathode ray tubes (CRTs), which are widely used in information display devices, have many advantages in terms of performance and price, but have disadvantages in terms of miniaturization or portability.

On the other hand, liquid crystal displays have been attracting attention as an alternative means of overcoming the shortcomings of CRT due to their advantages such as miniaturization, light weight, and low power consumption. It is the situation that is attached.

Unlike the CRT, the liquid crystal display is a non-light emitting device, and therefore, an external debt is required to display an image on the liquid crystal display panel. The light guide plate backlight is a surface light source device that supplies light from the rear side of the liquid crystal display panel, and consumes 70% or more of the driving power used in the liquid crystal display device due to the characteristics of the dimmer device. Therefore, the size and light efficiency of the liquid crystal display are changed by the light guide plate backlight structure, thereby affecting the mechanical and optical characteristics of the liquid crystal display.

The light guide plate backlight used in the liquid crystal display device is classified into a direct method and an edge method according to the position of the light source for supplying the light. In this case, the edge method is adopted, and in the case where the luminance is more important than the thickness, the direct method is generally adopted.

The edge light guide plate backlight includes a light source unit for generating light and a light guide unit for converting light generated from the light source of the light source unit into a uniform surface light source. The light guide portion includes a light guide plate for inducing light, and the light guide plate is a component that uniformly emits light generated from the light source to all regions of the liquid crystal display panel. In addition, the light source is generally provided with a CCFL (Cold Cathode Fluorescent Lamp, CCFL) backlight.

However, in the edge light guide plate backlight, since a light source of the CCFL backlight is located at one end or both ends of the light guide plate, a luminance difference occurs at a portion far from the light source portion, so that light incident to the light guide plate is scattered and diffused. The light reflecting structure which emits light toward the liquid crystal display panel direction is formed.

FIG. 1 is a front view illustrating a light guide plate on which a linear light reflection structure used in a conventional edge type light guide plate backlight is formed.

As illustrated in FIG. 1, the linear light reflection structure 33 may not easily emit light flowing into the light guide plate 30 to the surface of the light guide plate 30. The reason for this is that when the CCFL backlight uses the amount of light flowing toward the incident part of the light guide plate 30, the amount of light on the electrode side is smaller than the amount of light emitted from the central side of the CCFL backlight. In the process of propagation also in the interior of 30, the light reflecting structure of the linear light reflection structure in each region because it is reflected back from the cut portion of the edge of the light guide plate 30 does not form a uniform light distribution even in the light guide plate 30 ( 33) It has been installed by adjusting the gap.

However, even if the distance between the light reflection structure 33 is installed as described above, the four edges (A, B, C, D) and the edge center portion (E, F) of the light guide plate 30 is more luminance. There is a problem of being lowered.

FIG. 2 is a front view showing a conventional light guide plate and a processing tip for forming a light reflection structure on the light guide plate, and FIG. 3 is a front view showing a light emission path by a light reflection structure formed on the steel plate by a conventional processing tip. .

As shown in FIG. 2 or 3, the incident light 21 emitted from the light source 20 provided on one side of the light guide plate 30 is reflected by the light reflection structure 33. Here, the conventional light reflecting structure 33 forms a V-shaped groove in a V-cutting method on the light guide plate 30 without preheating using a processing tip. The light reflection structure 33 was provided.

However, according to the conventional method, the depth of the groove formed in the light guide plate 30 cannot be deeply formed, and the incident light 21 reflected by the light reflection structure 33 is formed by the rough surface of the groove. There has been a problem that the scattered light 31 is scattered to the surface of the light guide plate 30 without having a constant direction after being reflected.

Thus, in order to solve the problem of the scattered light 31, the prism film 40 is provided at a predetermined distance from the upper side of the light guide plate 30. The prism film 40 plays a role in which the scattered light 31 collects light in a direction perpendicular to the surface of the light guide plate 30. However, since the prism film 40 is an expensive material, there has been a problem in that the manufacturing cost of the surface light source device 10 is greatly increased.

Figure 4 is a side cross-sectional view showing a surface light source device equipped with an LED as a conventional light source.

CCFL backlight, which is used as a conventional LGP backlight, has mercury and has a problem of environmental pollution. In order to solve this problem, an LED backlight using an LED (luminescent diode, hereinafter referred to as LED) has been replaced, and since the LED corresponds to a point light source, when used as a light source 20 of the surface light source device 10, As shown in FIG. 5, there has been a problem that the arm part 35 is generated.

Accordingly, the present invention has been made to solve the problems of the prior art as described above, and the first object of the present invention is to provide a constant directionality of light reflected by the light reflection structure formed on the rear surface of the light guide plate by using a heated heating processing tip. It is to provide a surface light source device to have.

In addition, a second object of the present invention is to provide a surface light source device in which the light reflection structure provided on the rear surface of the light guide plate is provided in the form of a broken line or cross shape so that the distribution of the amount of light flowing into the light guide plate is uniform.

In addition, a third object of the present invention is to provide a surface light source device for linearizing a light emitting diode (LED) as a light source, including a lens unit provided with a lens.

Therefore, the surface light source device according to an embodiment of the present invention for achieving the above object, the surface light source device, a light guide plate; A light source unit disposed on one side of the light guide plate; And a light reflection structure formed on a rear surface of the light guide plate, wherein the light reflection structure is formed in a mirror surface without irregularities so that the reflected light has a constant direction.

In addition, the light reflection structure is formed on the light guide plate 110 in the form of a broken line, it is preferable that the arrangement of the broken line is alternately arranged.

In addition, the light reflection structure is preferably formed in the cross-shaped surface on the light guide plate (110).

On the other hand, the light source unit 120 includes a light emitting diode (LED) as a light source; And a lens unit provided in front of the light emitting diode (LED).

In addition, the lens unit 140 includes a lens 141 formed thereon; It is preferable that the light guide portion 143 formed on the bottom.

In addition, it is preferable that the width d and the height a of the lens portion satisfy 2d> a> d.

In addition, the height of the lens unit 140 is preferably 7 ~ 8mm.

In addition, the lens 141 is preferably formed of a hemispherical convex portion.

In addition, the light guide plate 110 is preferably made of a PMMA.

In addition, the angle of the groove formed in the light reflection structure is preferably formed to 53 ° ~ 60 °.

As described above, the surface light source device of the present invention is expensive to make the light reflected by the light reflecting structure formed on the rear surface of the light guide plate to have a constant direction by using a heat processing tip heated to a high temperature, thereby having a directivity. There is no need for a film, thereby reducing the production cost.

In addition, the light reflection structure provided on the rear surface of the light guide plate is provided in the form of a dashed line or cross, so that the luminance is uniform since the distribution of the amount of light flowing into the light guide plate is uniform.

In addition, there is an effect of preventing the generation of the dark area by including the lens portion provided with the lens to the line light source LED light source.

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

FIG. 5 is a front view illustrating a light guide plate having a light reflection structure having a broken line shape in a surface light source device according to a preferred embodiment of the present invention, and FIG. 6 is an enlarged front view of region G in FIG. 5.

FIG. 7 is a detailed view illustrating a light guide plate having a light reflection structure having surfaces arranged alternately in a dashed line in a surface light source device according to an exemplary embodiment of the present invention, and FIG. 8 is another preferred embodiment of the present invention. In the surface light source device according to the embodiment is a detailed view showing a light guide plate having a cross-shaped light reflection structure.

As shown in the drawing, the surface light source device 100 of the present invention includes a light guide plate 110, a light source unit 120, and light reflecting structures 111, 113, 115, and 117.

The light guide plate 110 is a material that transmits light well, for example, a transparent plastic material is used, and preferably a transparent acrylic resin (PAMA, Polymethyl metharcrylate, excellent PMMA) excellent in mechanical strength and excellent transmittance to visible light Is called). At this time, the thickness of the light guide plate 110 used is preferably used to the thickness of 4.5 ~ 5.5mm.

The light reflection structure 111 has a lateral surface in the form of a V-shape ('V') on the back surface of the light guide plate 110, and is formed in the form of a dot (dot) on the light guide plate 110, the light reflection It is preferable that the structure 111 is formed on the light guide plate 110 in the form of a broken line. At this time, it is preferable that the arm part 112 is not formed in the vicinity of the light reflection structure 113 by alternately providing the arrangement of the broken lines.

On the other hand, in another preferred embodiment, the shape of the light reflection structure 115 formed on the rear surface of the light guide plate 110 is provided in a cross shape. In this case, when the shape of the light reflection structure 115 is provided in a cross shape, the light guide plate 110 having the linear light reflection structure 111 may be more effectively prevented from generating the dark portion 112 where shadow lines are generated. It improves light reflection efficiency.

The light source unit 120 is disposed on one side of the light guide plate 110 and emits light generated by the light source of the light source unit 120 to the light guide plate 110. In this case, incident light incident from the light source unit 120 to the light guide plate 110 is vertically emitted to the surface of the light guide plate 110 by the light reflection structure. Here, the light source unit 120 includes a lens unit 140 and a light source.

9 is a cross-sectional view illustrating a light emission path in a light guide plate on which a light reflection structure processed by a heating working tip according to a preferred embodiment of the present invention is formed.

As shown in FIG. 9, the light reflection structure 117 formed of a high temperature heat processing tip (not shown) is processed into a mirror surface having a smooth surface without irregularities, so that diffuse reflection does not occur and specular reflection occurs. Lose.

In addition, when the light reflecting structure 117 is formed using the heating processing tip, the depth of the light reflecting structure 117 can be deeply formed, and thus the light reflecting surface is increased, thereby increasing the light reflecting luminance.

Here, one side of the heating working tip is provided with a preheating unit (not shown) for transferring heat to the heating working tip.

Meanwhile, an intaglio having a V-shape is formed on the light reflecting structure 117 by the heating processing tip in a V-cutting manner, and the reflection groove angle of the indented groove formed is 53 to 60 °. It is preferable to be. Here, the light is not emitted in a direction perpendicular to the light guide plate when it is outside the angle range (53 to 60 °) of the reflective groove.

10 is a state diagram showing the use of the lens unit of the surface light source device according to a preferred embodiment of the present invention, Figure 11 is a perspective view showing the lens portion of the surface light source device according to a preferred embodiment of the present invention.

As shown in FIG. 10 or 11, the lens unit 140 includes a lens 141 at an upper portion thereof, and a light guide unit 143 at the lower portion thereof. In addition, the lens 141 preferably has a curvature, and in this case, the lens is preferably formed of a hemispherical convex portion.

On the other hand, it is preferable that the width d, the length b, and the height a of the lens portion satisfy 2d> a> d. Here, in a preferred embodiment, the height a of the lens unit 140 is 7 to 8 mm.

The LED 130, which is a light source of the light source unit 120, is provided behind the lens unit 140 to emit light to the light guide plate 110 through the lens unit 140. In this case, the LED 130 corresponds to a point light source, and the line light source is made through the lens unit 140.

Hereinafter, the experimental results of the structure and characteristics of the surface light source device according to the present invention.

FIG. 12 is a graph comparing luminance characteristics of a light guide plate having a dashed light reflection structure and a light guide plate having a cross shape in a surface light source device according to a preferred embodiment of the present invention.

Referring to FIG. 12, the light guide plate 110 in which the light reflection structure 115 is formed in a cross shape exhibits higher luminance characteristics than the light guide plate in which the light reflection structure 113 is formed in a broken line shape.

Fig. 13 is a graph showing luminance characteristics when the lens unit of the present invention is applied and not applied.

Referring to FIG. 13, when the lens unit 140 is not provided in front of the LED 130, which is the light source of the light source unit 120, the luminance characteristics are not uniform, and in front of the LED 130 as the light source. When the lens unit 140 is provided, even luminance characteristics are shown.

Fig. 15 is a front view showing the optical characteristics shown on the screen when the height (a) of the lens portion of the light source portion of the surface light source device> the width (d) of the lens portion, and Fig. 16 is the width of the lens portion of the lens portion of the light source portion of the surface light source device ( d) * 2> height (a)> front view showing the optical characteristics shown on the screen when the width (d) of the lens portion, Figure 17 is the width (d) * 2 <height of the lens portion of the light source portion of the surface light source device (a) The front view which showed the optical characteristic shown on the screen at the time.

Referring to FIGS. 15 to 17, FIGS. 15 to 17 illustrate the light emission characteristics of the surface light source device according to the height of the lens with a width d of the lens unit 6 mm and a radius of curvature c of the lens 3 mm. This is a photograph of an experiment.

As shown in FIG. 15, when the height a of the lens unit is 4 mm, the light shape emitted from the LED, which is a light source, and reflected on the screen is divided into two parts. Therefore, the implementation of the point light source as the line light source has not been realized.

As shown in FIG. 17, when the height (a) of the lens unit was set to 15 mm, the light shape emitted through the LED and reflected on the screen was divided into a plurality of linear shapes. Accordingly, it can be seen that the light focusing effect of the light is reduced and the light utilization efficiency of the LED which is the light source is lowered.

As shown in FIG. 16, when the height a of the lens unit 140 was 7.5 mm, the light shape reflected on the screen 150 appeared in a linear shape. Accordingly, it can be seen that the conditions for linearizing the point light source are well satisfied. Therefore, when the width d, the length b, and the height a of the lens unit 140, which is a preferred embodiment of the present invention, satisfy 2d> a> d, the light of the LED 130 which is a point light source It can be seen that the most suitable conditions for the pre-light source.

14 is a graph comparing the luminance characteristics of the light reflection structure processed by the heating processing tip of the present invention with the lens unit and the luminance characteristics of the conventional surface light source device.

Referring to FIG. 14, the light reflection structure 117 is formed in a smooth surface without irregularities by the heating processing tip, and the lens unit 140 is provided in front of the LED 130 as a light source. The light source device 100 has a high luminance and uniform luminance characteristics as compared with the conventional surface light source device.

The above description is merely illustrative of the technical spirit of the present patent, and those skilled in the art to which the present patent belongs may have various modifications and variations without departing from the essential characteristics of the present patent.

In addition, the embodiments disclosed in the present patent are not intended to limit the technical spirit of the present patent but to describe the present invention, and the scope of the technical spirit of the present patent is not limited by these embodiments.

Therefore, the protection scope of the present patent should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present patent.

1 is a front view illustrating a light guide plate having a conventional linear light reflection structure used in a conventional edge-type light guide plate backlight.

2 is a front view showing a conventional light guide plate and a processing tip for forming a light reflection structure on the light guide plate.

3 is a front view showing a light emission path by the light reflection structure formed on the steel plate by a conventional working tip.

Figure 4 is a side cross-sectional view showing a surface light source device equipped with an LED as a conventional light source.

FIG. 5 is a front view illustrating a light guide plate having a light reflection structure having a broken line shape in a surface light source device according to a preferred embodiment of the present invention.

FIG. 6 is an enlarged front view of region G in FIG. 5.

FIG. 7 is a detailed view illustrating a light guide plate having a light reflection structure in which surfaces are alternately arranged in a dashed line in a surface light source device according to an exemplary embodiment of the present invention.

FIG. 8 is a detailed view illustrating a light guide plate having a light reflection structure having a cross shape in a surface light source device according to another exemplary embodiment of the present invention.

9 is a cross-sectional view illustrating a light emission path in a light guide plate on which a light reflection structure processed by a heating working tip according to a preferred embodiment of the present invention is formed.

10 is a state diagram showing the use of the lens portion of the surface light source device according to the preferred embodiment of the present invention.

11 is a perspective view illustrating a lens unit of a surface light source device according to a preferred embodiment of the present invention.

FIG. 12 is a graph comparing luminance characteristics of a light guide plate having a dashed light reflection structure and a light guide plate having a cross shape in a surface light source device according to a preferred embodiment of the present invention.

Fig. 13 is a graph showing luminance characteristics when the lens unit of the present invention is applied and not applied.

14 is a graph comparing the luminance characteristics of the light reflection structure processed by the heating processing tip of the present invention with the lens unit and the luminance characteristics of the conventional surface light source device.

Fig. 15 is a front view showing the optical characteristics shown on the screen when the height (a) of the lens portion> the width (d) of the lens portion of the light source portion of the surface light source device.

Fig. 16 is a front view showing the optical characteristics shown on the screen when the width d * 2> the height a> the width d of the lens portion of the lens portion of the light source portion of the surface light source device.

Fig. 17 is a front view showing the optical characteristics shown on the screen when the width d * 2 <height a of the lens portion of the lens portion of the light source portion of the surface light source device.

<Description of Symbols for Main Parts of Drawings>

10: surface light source device 20: light source

21: incident light 30: light guide plate

31: scattered light 33: light reflection structure

35: dark 40: prism film

50: processing tip 60: light emitting diode (LED)

100: surface light source device 110: light guide plate

111: light reflection structure 112: dark

113: light reflection structure 115: light reflection structure

117: light reflection structure 120: light source

130: LED (light emitting diode) 140: lens unit

141: lens 143: light guide portion

150: screen

Claims (10)

In the surface light source device, A light guide plate 110; A light source unit 120 disposed on one side of the light guide plate 110; And It includes; a light reflection structure formed on the back of the light guide plate 110, The light reflecting structure is a surface light source device, characterized in that formed in a mirror-free surface so that the reflected light has a certain direction. The method of claim 1, wherein the light reflecting structure, Surface is formed on the light guide plate 110 in the form of a broken line, the surface light source device, characterized in that the arrangement of the broken line is arranged alternately. The method of claim 1, wherein the light reflecting structure, Surface light source device, characterized in that the surface is formed in the cross-shaped light guide plate (110). The method according to any one of claims 1 to 3, The light source unit 120 includes a light emitting diode (LED) as a light source; And a lens unit provided in front of the light emitting diode (LED). The method according to claim 4, The lens unit 140, A lens 141 formed at an upper portion thereof; Surface light source device comprising a; light guide portion (143) formed in the lower portion. The method according to claim 4 or 5, The width (d) and height (a) of the lens portion, And a surface light source device satisfying 2d> a> d. According to claim 6, The height of the lens unit 140 is a surface light source device, characterized in that 7 ~ 8mm. According to claim 5, The lens 141 is a surface light source device, characterized in that formed by a hemispherical convex portion. The method according to any one of claims 1 to 3, The light guide plate 110 is a material of the surface light source, characterized in that the PMMA (PMMA). The method according to any one of claims 1 to 3, The angle of the groove formed in the light reflection structure is a surface light source device, characterized in that formed in 53 ° ~ 60 °.

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