KR101779930B1 - Light guide plate and Planar light source device the same - Google Patents

Abstract

The present invention relates to a light guide plate capable of implementing a narrow bezel and a slim structure, and a surface light source device. The surface light source according to the present invention includes: a cover bottom in which a receiving space is formed; the light guide plate which includes a planar light guide body which includes a light emission surface on the upper side thereof to emit light which is totally reflected inside and a reflection surface on the lateral side thereof to block the light leaked to the outside and at least one or more incident protrusions which are formed to protrude to the lower side of the light guide body with a reverse cone shape and include incident surfaces to which the light of a light source is incident on the lower ends thereof, and is configured to radially transmit the incident light through the incident surface to the inside of the light guide body through the incident protrusion; at least one or more light sources which are arranged on the lower side of the incident protrusion of the light guide plate and input the light to the inside of the light guide body through the incident surface of the light guide plate; and an optical sheet which is arranged on the upper side of the light guide plate.

Description

[0001] The present invention relates to a light guide plate and a planar light source device having the same,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar light source device, and more particularly, to a planar light source device having a narrow bezel structure and a slim structure, and a planar light source device having the same.

Unlike other display devices, a liquid crystal display device (hereinafter, referred to as 'LCD'), which is a flat display device, can not emit light by itself, and therefore an external light source is necessarily required to realize a high- . Therefore, the LCD further includes a planar light source device as a backlighting light source in addition to the liquid crystal panel, so that the planar light source device uniformly supplies a high-luminance light source to the liquid crystal panel to realize an image.

The surface light source device is an illumination device for realizing an image of a display device such as an LCD and is classified into a direct lighting type or an edge lighting type surface light source device depending on the position where the light source is disposed . In addition, as a light source of the surface light source device, a light emitting diode (hereinafter referred to as 'LED') having advantages such as small size, low power consumption and high reliability is mainly used.

FIG. 1 is a plan view showing a main configuration of a side surface type light source device, FIG. 2 is a side view showing a main configuration of a direct type surface light source device, and FIG. 3 is a cross- Fig.

As shown in FIG. 1, the side surface type light source device is configured such that a light source module 12 is disposed on the side of the light guide plate 11 to provide light into the light guide plate. Here, the light guide plate 11 has a plate-like shape having a predetermined thickness, one side where the light source module is disposed forms a light incidence surface 11a on which light is incident, and the upper surface forms a light output surface 11b on which light is emitted do. The light source module 12 is composed of an LED array in which a plurality of LEDs 12a are mounted on the substrate 12b at regular intervals.

In the side surface type light source device having the above-described structure, the light of a plurality of point light sources emitted from the LED 12a is incident into the light guide plate 11 through the light incidence surface 11a, passes through the light guide plate, And is emitted to the light-outgoing surface 11b on the upper surface. Although the side surface type light source device has the advantage that the light source is disposed on the side of the light guide plate, the side surface type light source device disadvantageously dissipates heat from the light source module and increases the width of the bezel to cover the luminance deviation of the light source module and the light-

2, the direct-type surface light source device is configured such that a light source module 22 is disposed under the diffusion plate 21 to provide light to the diffusion plate 21 on the upper side. The light source module 22 includes a plurality of LEDs 22a arranged in the horizontal and vertical directions to form a plurality of point light sources 22a, Of light. The light of the plurality of point light sources emitted from the light source module 22 is diffused while passing through the diffusion plate 21 to provide light of the surface light source. At this time, a sufficient interval should be ensured between the light source module 22 and the diffusion plate 21 so that the light of the point light source by the light source module 22 is not visible.

Therefore, the direct-type surface light source device has advantages in that the light source is disposed under the diffusion plate and can reduce the width of the bezel and is advantageous for heat dissipation, but has a disadvantage that it is disadvantageous in slimming since a sufficient space must be secured between the light source and the diffusion plate.

In order to compensate for the drawbacks of the direct-type surface light source device, a direct-type surface light source device in which a diffusion lens is further provided on the LED is proposed in Korean Patent No. 10-1398186 (prior art document). 3, a diffusion lens 23 is mounted on the LED 22a, and light emitted from the LED 22a passes through the diffusion lens 23, And then passes through the diffusion plate 21. Therefore, in the surface light source device, since the light of the point light source of the LED 22a is primarily diffused by the diffusing lens 23, the distance between the light source and the diffusing plate can be reduced.

As described above, the surface light source device having the diffusing lens has an advantageous effect of reducing the width of the bezel while reducing the width of the bezel. However, since a separate diffusing lens must be mounted on the upper side of the LED, a long time is required for the assembling process, There is a problem that manufacturing costs are increased due to use of parts. In addition, since the surface light source device of the prior art document includes a diffusion lens interposed between the light source and the diffusion plate, the surface light source device still shows a limit to the slimness of the surface light source device.

Korean Registered Patent No. 10-1398186 (Registered, Lens for Side-Emitting Type Light Emitting Diode, Backlight Unit and Display Apparatus Including the Same)

SUMMARY OF THE INVENTION It is an object of the present invention to provide a light guide plate having a structure capable of reducing the width of a bezel and a surface light source device having the same.

It is another object of the present invention to provide a light guide plate having a structure in which light of a point light source is not visually recognized without additional parts, thereby realizing slimming and a surface light source device having the same.

According to an aspect of the present invention, there is provided a light guiding plate comprising: a plate light-guiding body having a light-exiting surface on which light totally reflected from the light exits, and a reflective surface on a side surface, And at least one light-projecting protrusions protruding in an inverted conical shape below the light-guiding body, the lower end of the light-guiding body having a light incidence surface on which light from the light source is incident, And is radially transmitted to the inside of the light guide body.

Here, the light-guiding body has a light-emitting surface at a position corresponding to the light-incident projection, and a concave groove is formed in a shape corresponding to the light-incident projection.

The reflecting surface of the light guiding body may have a reflecting surface facing the center of the light guiding body toward the lateral center of the light guiding body, , And a lower inclined surface.

According to another aspect of the present invention, there is provided a surface light source device including: a cover bottom having a storage space therein; A light guide body having a plate-like light reflection main body having a light emitting surface on a top surface through which light is totally reflected and a light reflecting surface on a side surface for shielding light leaking to the outside, and a light guide body protruding in an inverted conical shape below the light guiding body, A light guide plate configured to include at least one light incident projection having a light entrance surface through which light is incident, and light incident through the light entrance surface is radially transmitted to the inside of the light guide body through the light projection; At least one light source disposed below the light incident projection of the light guide plate and allowing light to enter the light guide body through the light incident surface of the light guide plate; And an optical sheet disposed on the light guide plate.

In the surface light source device of the present invention, the cover bottom may include at least one groove portion in which the light-projecting projection of the light guide plate is received, and the light source is disposed below the light-incident projection in the groove portion.

As described above, the LED light source is disposed below the light guide plate, thereby reducing the width of the bezel of the surface light source device.

In addition, since the light of the LED light source is diffused through the light incident projection of the lower portion of the light guide plate and is incident into the light guide plate, the interval between the light source and the light guide plate can be reduced, thereby realizing the slimness of the surface light source device.

1 is a plan view showing a main configuration of a side surface type surface light source device,
2 is a side view showing a main configuration of a direct-type surface light source device,
3 is a side view showing a main configuration of a direct-type surface light source device having a diffusion lens according to a conventional technique,
4 is a cross-sectional view of a planar light source device according to an embodiment of the present invention,
5 is a perspective view illustrating a light guide plate according to an embodiment of the present invention,
FIG. 6 is a cross-sectional view showing the light incidence characteristic of the incident light projection, which is the main part of FIG. 5,
FIG. 7 is a sectional view for explaining the shape characteristics of the incident light projection, which is the main part of FIG. 5,
Fig. 8 is a cross-sectional view showing various examples of light incidence surfaces for the light incidence protrusions, which are the main part of Fig. 5, and Fig.
Fig. 9 is a cross-sectional view showing a reflective surface of the light guiding body, which is the main part of Fig. 5;

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 is a cross-sectional view illustrating a planar light source device according to an embodiment of the present invention.

4, the surface light source device of the present invention includes a light guide plate 100, a light source module 200 disposed below the light guide plate to provide light into the light guide plate, a reflective sheet 300 An optical sheet 400 laminated on the upper side of the light guide plate, and a cover bottom 500 on which a storage space is formed. Here, the light guide plate 100, the light source 200, the reflective sheet 300, and the optical sheet 400 are mounted on the cover bottom 500 and are fixed to the cover bottom at the upper side of the cover bottom 500, (600).

Specifically, the light guide plate 100 is a light switching device that converts the light of at least one point light source incident from the light source module 200 into a surface light source through total internal reflection. The light guide plate 100 is made of a transparent acrylic resin having a predetermined refractive index. For example, a resin such as polymethylmethacrylate (PMMA), poly styrene (PS), meta styrene (MS), or polycarbonate have.

The light guide plate 100 according to the present invention receives light from a lower light source. The light guide plate 100 for this purpose includes a light guide body 110 having a rectangular plate shape for converting light into a surface light source, And an incident light projection 120 protruding downward from the light guide body 110. A detailed description of the light guide plate having the above-described structure will be given later.

The light source module 200 may be a light source disposed under the light guide plate 100 and providing light to the inside of the light guide plate and may be an LED module in which the LEDs 220 are mounted on the substrate 210. In particular, the light source module 200 is disposed under the light guide plate 100 such that the LEDs 220 are positioned below the light incident protrusions 120.

The reflective sheet 300 may be formed of a sheet or a film having excellent light reflectance, which is configured to improve the brightness by causing light leaked downward from the light guide plate 100 to enter the light guide plate. The optical sheet 400 is a light control sheet that is stacked on the light guide plate 100 and controls the optical characteristics of light emitted from the light guide plate 100. The light guide plate 400 focuses the light emitted from the light guide plate 100, A prism sheet for controlling light, and a diffusion sheet for improving light uniformity.

The cover bottom 500 has a structure in which each component is accommodated therein and is protected by the cover bottom 500. The bottom edge of the square bottom is divided into side walls which are bent upward, and a storage space is formed therein by the side walls. The reflective sheet 300, the light source module 200, and the light guide plate 100 are sequentially seated in the storage space.

In particular, the cover bottom 500 of the present invention includes a light source groove 520 having a concave shape for preventing the light source module 200 from interfering with the light incident projection 120 of the light guide plate 100, . The bottom surface of the cover bottom 500 has a concavo-convex structure due to the concave light source grooves relative to the protruding surface for supporting the light guide plate 100. The bottom surface of the concavo-convex structure increases resistance to flexural deformation, It is possible to more reliably protect the respective parts with respect to each other.

The guide panel 600 has a structure for fixing the light guide plate 100, the light source module 200, the reflection sheet 300 and the optical sheet 400 to be housed in the cover bottom 500. The guide panel 600 has a square flange ≪ / RTI > The guide panel 600 is fastened along the edge of the cover bottom 500 to protect various components from external impact while pressing and fixing them.

FIG. 5 is a perspective view of a light guide plate according to an embodiment of the present invention, FIG. 6 is a cross-sectional view taken along a direction II in FIG. 5 showing light incidence characteristics of an incident light projection, FIG. 8 is a cross-sectional view showing various examples of the light incidence surface with respect to the light incident projection, which is the main part of FIG. 5. FIG.

5, a light guide plate 100 according to an embodiment of the present invention includes a light guide body 110 on a plate and at least one light incident projection 120 protruding downward from the light guide body.

Specifically, the light guide body 110 has a rectangular plate shape having a predetermined thickness and area for emitting light, which is incident through the light incident projection 120, into a surface light source and emitting the light. The light guiding body 110 includes a light emitting surface 110b on the upper surface through which light is emitted and a reflective surface 110c on the side surface for blocking light leaking to the outside.

The light incident protrusion 120 is formed by incidence of light emitted from the light source module 200 and guiding the light to the light guiding body 110. The predetermined position of the light guiding body 110 is recessed downward. Accordingly, the light guiding body 110 also forms a conical groove 111 in which the light emitting surface 110b on the upper side of the light incident projection 120 is recessed like a sink hole. At least one of the light-projecting protrusions 120 is arranged in the zigzag direction in the lateral and longitudinal directions with respect to the light guide body 110. The distance between the light incident projections 120 arranged in the zigzag direction is kept constant so that the light is uniformly distributed in the light guide plate 100 to prevent the unbalance of light.

The light incident projection 120 has an inverted conical shape having a circular cross section and becoming narrower toward the lower side, and a lower end surface forms a light incident surface 120a through which the light from the light source module 200 is incident. Therefore, the upper and lower surfaces of the light incident projection 120 form curved total reflection surfaces 120 'and 120 ", and the light incident from the light incidence surface 120a of the lower end surface, And is guided into the light guide body 110 while repeating total reflection along the slopes 120 ', 120 ". The surface of the conical groove 111 on the upper surface of the light incident projection 120 and the surface of the light incident surface 120a on the lower surface of the light incident projection 120 are concentric circles.

(1/n)의 값보다 커야 하고, 입광 돌기(120) 내부로 입사되는 빛의 지향각(90˚-α/2)보다 입광 돌기(120)의 끝점각(90˚-θ₂)이 커야 하며, 이러한 조건에서 입광면(121)으로 입사되는 광의 손실이 최소가 된다(여기서, α는 LED의 지향각이고, θ₂는 입광 돌기 하면의 끝점각이다).At this time, the light incident projection 120 can control the total reflectance of light incident from the light incidence surface 120a according to the length (i.e., the length and thickness of the light incident projection) of the total reflection surfaces 120 'and 120 " 7, the value of the total reflection critical angle? Of the light incident from the light source module 200 as a condition for total reflection in the light incident projection 120 is expressed by sin?

(90 占 -? 2) of the incident light projection 120 is larger than the incident angle (90 占 -? / 2) of the light incident into the incident light projection 120 , The loss of light incident on the light incidence surface 121 is minimized under this condition (where? Is the directivity angle of the LED and? 2 is the end incidence angle of the light incident surface).

In addition, the length and thickness of the light incident projection 120 can be formed on the basis of the values calculated from the equations (1) to (5).

The value of the diameter d 1 of the light incident projection 120 is arbitrarily determined and the refractive index n of the light guide plate 100 in accordance with the change in the value of the incident angle y of the light source 200 The value of the end tilt θ 1 of the surface of the conical groove 111 (that is, the top surface of the incident light projection) is represented by a table and the value of the radius r 1 of the incident light projection on the surface of the conical groove 111 .

For example, if d 1 is 20 mm, r 1 is calculated as 13.9 mm.

Then, the refractive index n of the light guide plate 100, the directivity angle of the light source, the diameter d 2 of the light incidence surface, the thickness t of the light guide plate, and the end stitch angle θ 2 of the light- The value of the radius r of the incident light projection 120 is calculated by using the equation 3 and the value of the radius r 2 of the incident light projection calculated in the equation 3 and the equation 4, The value of the outermost distance h 1 is calculated and the shortest distance h 2 from the light incidence surface to the light exit surface using the value of the outermost distance h 1 of the light guide plate calculated in [Equation 4] and [Equation 5] ).

For example, when t = 2mm, n = 1.49 (refractive index of PMMA), α = 100 and d₂ = 5mm, r₂ = 11.7mm is calculated and h₁ = 4.7mm and h₂ = 0.5mm are calculated.

8, the light incident surface 120a formed on the lower end surface of the light incident projection 120 may have a planar shape as shown in (a), a concave conical shape as shown in (b) The concave cone shape can be obtained. The planar light incidence surface 120a is uniformly incident on the light incidence surface 120a and uniformly incident on the light incidence surface 120a of the light source module 200. The light incidence surface 120a having a concave conical shape or a conical shape, It is possible to prevent a hot spot phenomenon in which light is concentrated in the vertical direction by raising the refractive index of light by an inclined surface or a curved surface with respect to the light emitted from the module 200. In addition, the concave cone-shaped light incidence surface has rounded corners, which can prevent the light incidence caused by the vertexes.

Fig. 9 is a cross-sectional view showing a reflective surface of the light guiding body, which is the main part of Fig. 5;

As shown in the figure, the reflective surface 110c constitutes a side surface portion of the light guiding body 110, and prevents the light totally reflected in the light guiding body from leaking to the side surface. The reflective surface 110c may be an inclined surface and the inclined surfaces may be upper and lower inclined surfaces symmetrical with respect to the transverse center C of the light guide body 110. [ In addition, the inclined surface may be formed to have an inclination angle of about 30 to 60 degrees, and may be formed to have an inclination angle of about 45 degrees.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.

100: light guide plate
110: light guiding body 111: conical groove
110b: Outgoing light surface 110c:
120: incident light projection 120a:
120 ': Top surface total slope 120'':
200: light source module 300: reflective sheet
400: optical sheet 500: cover bottom
600: Guide panel

Claims (6)

A light guiding body on a plate having a light emitting surface on an upper surface through which light totally reflected from the light exits and a light reflecting surface on a side for blocking light leaking to the outside; And
At least one light incident projection protruding downward from the light guiding body in an inverted conical shape and having a light incident surface through which the light of the light source is incident,
The light output surface at a position corresponding to the light-incoming projection forms a concave groove in a shape corresponding to the light-incoming projection,
And the light incident through the light incidence surface is radially transmitted through the light incident projection to the inside of the light guiding body. delete The light-emitting device according to claim 1,
A concave cone shape, or a concave cone shape. The light-emitting device according to claim 1,
Wherein the light guide plate has upper and lower inclined surfaces for reflecting light toward the transverse center of the light guide body. A cover bottom in which a storage space is formed;
A light guide body having a plate-like light reflection main body having a light emitting surface on a top surface through which light is totally reflected and a light reflecting surface on a side surface for shielding light leaking to the outside, and a light guide body protruding in an inverted conical shape below the light guiding body, Wherein the light emitting surface is formed with at least one light incident projection having a light incident surface on which light is incident, the light emitting surface at a position corresponding to the light projection has a concave groove corresponding to the light incident projection, A light guide plate configured to transmit light radially through the light incident projection into the light guide body;
At least one light source disposed below the light incident projection of the light guide plate and allowing light to enter the light guide body through the light incident surface of the light guide plate; And
And an optical sheet disposed on the light guide plate. 6. The method of claim 5,
Wherein the cover bottom has at least one groove portion in which the light incident projection of the light guide plate is received,
Wherein the light source is disposed below the light incident projection in the groove portion.

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