CN100445837C - Surface light-emitting device and its light guide plate - Google Patents

Abstract

The present invention discloses an area light emitting device and a light guiding board thereof. The area light emitting device comprises at least one point light source and the light guiding board, wherein the light guiding board comprises at least one light incident surface, a bottom surface which is crossed with the light incident surface and a light emergent surface which is opposite to the bottom surface; the light incident surface is provided with a plurality of cutting grooves, and the widths or the depths of the cutting grooves are in a gradient type change; the point light source is arranged to be just opposite to the groove with the maximum width or the maximum depth.

Description

Surface light-emitting device and its light guide plate

【Technical field】

The invention relates to a surface emitting device and a light guide plate thereof, in particular to a surface emitting device used in a liquid crystal display and a light guide plate thereof.

【Background technique】

Since the liquid crystal in the liquid crystal display panel itself does not have light-emitting characteristics, in order to achieve the display effect, it is necessary to provide a surface light-emitting device for the liquid crystal display panel. Its function is to supply a surface light source with sufficient brightness and uniform distribution to the liquid crystal display panel.

A surface light-emitting device in the prior art is shown in FIG. 1 and FIG. 2 , which is disclosed in Chinese Patent Application No. 01112454 published on November 21, 2001. The surface light-emitting device includes a light source 100 and a light guide plate 101 .

The light source 100 has two light emitting parts 102 , and the light emitting diodes 21 are arranged in the light emitting parts 102 . One end surface (not shown) of the light guide plate 101 is opposite to the light source 100, and the area facing the light emitting part 102 is provided with a plurality of triangular pyramid-shaped cut grooves 111a, and the plurality of cut grooves 111a are divided into two groups to form two The light diffusing part 111 .

The light emitted from the light emitting diode 21 enters the light guide plate 101 through the light receiving area 126a opposite to the light emitting portion 102, and is incident at a certain angle because the triangular pyramid-shaped cut groove 111a has two inclined surfaces relative to the end face of the light guide plate. The light emitted by the light diffusing portion 111 will be diffused and then enter the light guide plate 101 , so as to improve the uniformity of the light emitting brightness on the light emitting surface (not shown) of the light guide plate 101 .

However, since the light emitting diode 21 is a point light source, the light emitted by it has a certain divergence angle, and the incident angles of the light incident on different slots 111a are also different, so the slots 111a of the surface light emitting device are constant Obviously, the different diffusion effects on light rays at different incident angles have not been fully considered. Therefore, although the surface light-emitting device can achieve a certain degree of uniformity of light output brightness through the cut groove 111a, the effect is still unsatisfactory.

【Content of invention】

In order to overcome the problem of insufficient uniformity of the emitted light brightness of the surface light-emitting device in the prior art, the present invention provides a surface light-emitting device with higher uniformity of the emitted light brightness.

The invention also provides a light guide plate which can cooperate with a point light source and make the brightness uniformity of the emitted light higher.

The technical solution adopted by the present invention to solve the technical problem is to provide a surface light-emitting device, which includes at least one point light source and a light guide plate, and the light guide plate includes at least one light incident surface, a bottom surface intersecting the light incident surface, and a The light exit surface opposite to the bottom surface, wherein the at least one light incident surface has a plurality of cut grooves, the at least one point light source is arranged directly opposite to the cut groove with the largest width, and the width of the cut groove is greater than that of the light facing the point light source. The incidence surface gradually decreases toward both sides, and the depth of the groove is constant.

The technical solution adopted by the present invention to solve another technical problem is to provide a light guide plate, which includes at least one light incident surface, a bottom surface intersecting the light incident surface, and a light exit surface opposite to the bottom surface, wherein, The at least one light incident surface has a plurality of slits, the point light source is arranged directly opposite to the slit with the largest width, the width of the slit gradually decreases from the light incident surface facing the point light source to both sides, the The depth of the groove is constant.

Compared with the prior art, because the plurality of slits in the present invention change in a gradient manner, their width gradually decreases from the light incident surface facing the point light source to both sides, so that the slits farther away from the point light source A greater ability to diffuse light is obtained, so that the end corner area of the light guide plate receives more light and improves the overall uniformity of the light output brightness of the light exit surface.

【Description of drawings】

Fig. 1 is a plan view of a prior art surface emitting device.

FIG. 2 is a perspective view of a light guide plate of the surface emitting device shown in FIG. 1 .

Fig. 3 is a perspective view of the first embodiment of the surface light-emitting device of the present invention.

Fig. 4 is a plan view of a light guide plate and a point light source of the first embodiment of the surface light-emitting device of the present invention.

Fig. 5 is a schematic diagram of a partial light path of a light guide plate and a point light source in the first embodiment of the surface light-emitting device of the present invention.

Fig. 6 is a perspective view of the second embodiment of the surface light-emitting device of the present invention.

Fig. 7 is a plan view of a light guide plate and a point light source of a second embodiment of the surface light-emitting device of the present invention.

【Detailed ways】

Please refer to FIG. 3 and FIG. 4 , which are the first embodiment of the surface light-emitting device of the present invention. The surface light-emitting device 30 includes a light guide plate 31 , two point light sources 33 and a reflector 35 . The light guide plate 31 is a wedge-shaped light guide plate, which includes a light incident surface 313 , a bottom surface 315 intersecting the light incident surface 313 , and a light exit surface 311 opposite to the bottom surface 315 . The two point light sources 33 are arranged relative to the light incident surface 313 and may be light emitting diodes or small light bulbs. The bottom surface 315 of the light guide plate 31 is provided with a plurality of regularly distributed dots 37 , and the light emitting surface 311 is provided with a plurality of V-shaped grooves 3111 . The reflective plate 35 is attached to the bottom surface 315 of the light guide plate 31 , and the reflective plate 35 can also be replaced by a reflective film coated on the bottom surface 315 and the dots 37 .

A plurality of V-shaped cut grooves 3131 opposite to the point light source 33 are arranged on the light incident surface 313. The depth D of the plurality of cut grooves 3131 is constant, and the width W is from the light incident surface 313 facing the point light source 33 to both sides. side gradually decreases. The slot 3131 is perpendicular to the light emitting surface 311 and passes through the light emitting surface 311 and the bottom surface 315 .

As shown in FIG. 5 , it is a principle diagram of the diffusion of light emitted by the light emitting diodes 33 by the plurality of slots 3131 , and the details are as follows. When the light guide plate 31 does not have the slot 3131, the light 331 will be incident on the virtual plane 3133 (the plane shown by the dotted line), and enter the light guide plate 31 with the light 3311 after refraction; when the light guide plate 31 has the slot 3131 of the present invention When the light 331 is incident on the inclined surface 3131a inclined relative to the light incident surface 313, it will be refracted as a light 3313 and enter the light guide plate 31. Comparing the travel paths of the light 3311 and the light 3313, it can be seen that the diffusion angle of the light 3313 is relatively large. Moreover, when the light 332 is incident on the virtual plane 3131c parallel to the inclined surface 3131a, it will enter the light guide plate 31 as light 3321 after being refracted; For the light 3323 to enter the light guide plate 31, comparing the traveling paths of the light 3321 and the light 3323, it can be seen that the diffusion angle of the light 3323 is relatively large, that is to say: because the width W of the cut groove 3131 of the present invention is from the light directly facing the point light source 33 The incident surface 313 gradually decreases toward both sides, and the light divergence characteristic of the light emitting diode 33 cooperates with the change of the slopes 3131a and 3131b of the slot 3131, so that the slot 3131 farther away from the point light source 33 obtains a better response to the light 332. The large diffusion ability further enables the area of the end corner 31a of the light guide plate 31 to receive more light and improves the overall uniformity of the light output brightness of the light exit surface 311 .

Part of the light entering the light guide plate 31 after diffusing from the plurality of slots 3131 exits directly through the light exit surface 311 , and the other part of light exits from the light exit surface 311 after being scattered by the dots 37 on the bottom surface 315 . The reflector 35 can reflect the light leaked from the bottom surface 315 back to the light exit surface 311 to be emitted, thereby improving the brightness of the emitted light. The plurality of V-shaped cut grooves 3111 provided on the light emitting surface 311 also converge the light to further improve the brightness of the emitted light.

Please refer to FIG. 6 and FIG. 7 again, which are the second embodiment of the surface light-emitting device of the present invention. The surface light emitting device 50 also includes a light guide plate 51, two pairs of point light sources 53 and a reflector 55. The difference between it and the surface light emitting device 30 shown in FIG. 3 is that the light guide plate 51 is a flat light guide plate, and the light guide plate 51 includes two opposite light incident surfaces 513, and the two pairs of point light sources 53 are respectively disposed opposite to the two light incident surfaces 513.

The farther the grid dots 57 on the bottom surface 515 of the light guide plate 51 are from the point light source 53, the larger the size of the grid dots 57 is to fully scatter the light away from the point light source 53 and improve the overall uniformity of the light output surface 511.

Both of the two light incident surfaces 513 are provided with a plurality of slots 5131, and because the light received by the slots 5131 away from the point light source 53 is obliquely incident, when the depth D of the slots 5131 is deep, the bottom of the slots 5131 is difficult to receive light Therefore, the depth D of the cut groove 5131 is designed to gradually decrease from the light incident surface 513 facing the point light source 53 to both sides. The width W of the slot 5131 also gradually decreases from the light incident surface 513 facing the point light source 53 to both sides, so as to improve the overall uniformity of the light output brightness of the light exit surface 511 .

Claims (7)

1. A surface light-emitting device comprising at least one point light source and a light guide plate, the light guide plate comprising at least one light incident surface, a bottom surface intersecting the light incident surface and a light exit surface opposite to the bottom surface, the at least A light incident surface has a plurality of slits, the at least one point light source is arranged facing the slit with the largest width, and the width of the slit gradually decreases from the light incident surface facing the point light source to both sides, and the feature is that , the depth of the groove is constant. 2. The surface emitting device according to claim 1, wherein the cut groove is a V-shaped groove. 3. The surface emitting device according to claim 1, wherein the point light source is a light emitting diode or a small light bulb. 4. The surface emitting device according to claim 1, further comprising a reflective plate, the reflective plate is located on the bottom side of the light guide plate. 5. The surface emitting device according to claim 1, wherein the light emitting surface of the light guide plate has a plurality of V-shaped grooves. 6 . The surface emitting device according to claim 1 , wherein a plurality of scattering dots are arranged on the bottom surface of the light guide plate. 6 . 7. A light guide plate for a point light source, comprising at least one light incident surface, a bottom surface intersecting the light incident surface, and a light exit surface opposite to the bottom surface, the at least one light incident surface has a plurality of cut grooves , the point light source is arranged facing the slot with the maximum width, the width of the slot gradually decreases from the light incident surface facing the point light source to both sides, and the feature is that the depth of the slot is constant.

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