Side emitting backlight module

Sidelight backlight module

The present invention relates to an edge-lit backlight module, and more particularly to an edge-lit backlight module using a light-emitting diode as a light source.

The conventional display is a uniform surface light source required for the display panel to be provided by the backlight module. Referring to FIG. 1 , a conventional edge-lit backlight module 100 includes a light guide plate 110 , a turning prism sheet 120 , a diffuser film 130 , and a reflector 140 . A reflector 152 and a plurality of point sources 150, such as light emitting diodes (LEDs). The diffusion sheet 130 and the reverse diaphragm 120 are disposed above the light guide plate 110. The plurality of point light sources 150 are disposed on one side of the light guide plate 110, and the reflection plate 140 is disposed below the light guide plate 110.

Referring to FIG. 2, the upper surface of the light guide plate 110 has a sandblasting microstructure 112, and the lower surface has a V-cut micro-optical structure 114. The light beam emitted from the point source 150 is incident on one end of the light guide plate 110, and is guided to the other end of the light guide plate 110 by the principle of total reflection. The V-cut micro-optical structure 114 on the lower surface of the light guide plate 110 breaks its total reflection phenomenon during the conduction of the light beam, and tends to be emitted from the upper surface of the light guide plate 110. The sandblasting microstructure 112 breaks the total reflection phenomenon of the light beam on the upper surface of the light guide plate 110 and causes the light beam to be scattered, so that the light beam is uniformly emitted from the upper surface of the light guide plate 110.

Since the conventional edge-lit backlight module 100 adopts the point light source 150, the light guide plate 110 needs to provide a sufficiently large light-mixing region R on one side of the point light source 150, so that the light beams emitted from the plurality of point light sources 150 can pass through. Mix light to achieve uniform diffusion. Light spots S1, S2 (hot spots) as shown in Fig. 3A are formed in the light mixing region R.

Referring to FIG. 3A, since the conventional edge-lit backlight module 100 uses the light-emitting diode 150 as a light source, the light-emitting diode 150 is a directional light source having a light field F and other light-emitting diodes. The beams at the edge of the light field F of the polar body intersect to form spots S1, S2 in the light mixing region R. Therefore, the light beam of the light-mixing region R is not uniform, and it is impossible to provide a uniform surface light source for the display panel.

In the prior art, although the density of the blasting microstructures 112 on the upper surface of the light guide plate 110 can be enhanced to reduce the spot phenomenon, increasing the density of the blasting microstructures 112 results in uneven brightness as shown in FIG. 3B. The light-incident side of the light guide plate 110 is brighter (the area where the oblique line is denser), and is darker (the area where the oblique line is thinner) with the beam transmission direction G, and a more pronounced halo H is formed, so that the display panel is not provided uniformly. Surface light source.

The object of the present invention is to provide an edge-lit backlight module that attenuates the phenomenon of light spots and halation.

Other objects and advantages of the present invention will become apparent from the technical features disclosed herein.

An embodiment of the present invention is an edge-lit backlight module including a plurality of light-emitting diodes, a light guide plate, a brightness enhancement film, and a diffusion for achieving one or a portion or all of the above or other purposes. sheet. Each of the light-emitting diodes has a light-emitting surface, and the light-emitting surfaces of the light-emitting diodes are all facing in the same direction. The light guide plate is disposed on one side of the light emitting diode and has a light incident surface, a light exit surface and a bottom surface. The light incident surface of the light guide plate faces the light emitting surface of the light emitting diode. The light emitting surface of the light guide plate is adjacent to one side of the light incident surface. The bottom surface of the light guide plate is opposite to the light exit surface and adjacent to the other side of the light incident surface, and the bottom surface has a plurality of micro-optical structures and a plurality of flat regions. The flat zone intersects the light incident surface at a boundary line. The positions of the flat regions correspond to the light-emitting surfaces of the light-emitting diodes, respectively. The brightness enhancement film is disposed above the light exit surface of the light guide plate. The diffusion sheet is disposed above the brightness enhancement film.

In an embodiment of the invention, the flat region of the bottom surface of the light guide plate has a width and a depth, and the width of the flat region is parallel to the boundary line, and the direction of the depth is perpendicular to the boundary line. In one embodiment, the depth is between 3 microns and 30 microns. The illuminating mask of each of the illuminating diodes has a width, and the direction of the width of the illuminating surface is parallel to the boundary line. In one embodiment, the width of the flat portion of the light guiding plate is the width of the illuminating surface of the corresponding illuminating diode. 1.1 to 3 times.

In an embodiment, the light emitting diode comprises a first light emitting diode and a second light emitting diode. The flat zone includes a first flat zone and a second flat zone. The first light emitting diode corresponds to the position of the first flat region, and the second light emitting diode corresponds to the position of the second flat region. At this time, the depth of the first flat region is smaller than the depth of the second flat region.

In one embodiment, the micro-optical structure of the bottom surface of the light guide plate is a triangular prism or a V-shaped groove, and each of the triangular prisms or the V-shaped groove has a starting point and an extending direction, and the starting point is adjacent to the flat area. The extending direction is perpendicular to the boundary line and parallel to the bottom surface of the light guide plate. The flat zone is defined by the virtual connections and boundaries of the starting point of the triangular prism or V-shaped groove. In one embodiment, the virtual line of the starting point of the triangular prism or V-shaped groove includes a V-shaped line segment.

In one embodiment, the virtual wiring corresponds to the illuminating light field profile of each of the light emitting diodes.

In one embodiment, the shape of each flat zone is selected from the group consisting of a rectangle, a triangle, an arch, and a half arc.

In one embodiment, the triangular prisms or the V-shaped grooves are arranged side by side on the bottom surface to form a structure having a plurality of peaks and a plurality of valleys.

In one embodiment, the triangular prism or the V-shaped groove has one end portion, and the length of the end portion in the extending direction is between 3 micrometers and 30 micrometers, and the height or depth of the end portion is within the length of the end portion. The starting point of the triangular prism or the V-shaped groove is increased in the extending direction to a predetermined height or depth.

In one embodiment, the flat region of the bottom surface is a sandblasted surface. In one embodiment, the light exit surface of the light guide panel is a sandblasted surface.

In the embodiment of the present invention, in the region of the bottom surface of the light guide plate close to the light incident surface, a flat region is provided corresponding to the light emitting surface of the light emitting diode, and the problem of the light spot can be improved without strengthening the density of the sandblasting microstructure on the surface of the light guide plate. And does not increase the halo phenomenon.

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the embodiments of the invention. The directional terms mentioned in the following embodiments, such as up, down, left, right, front or back, etc., are only directions referring to the additional drawings. Therefore, the directional terminology used is for the purpose of illustration and not limitation.

Please refer to FIG. 4 , which is a schematic diagram of an edge-lit backlight module 200 according to an embodiment. The backlight module 200 includes a plurality of LEDs 250 , a light guide 210 , a brightness enhancement film 220 , a diffusion sheet 230 , and a Reflecting plate 240. Each of the light-emitting diodes 250 has a light-emitting surface 252, and the light-emitting surfaces 252 of the light-emitting diodes 250 are all facing in the same direction. The light guide plate 210 is disposed on one side of the light emitting diode 250 and has a light incident surface 212, a light exit surface 214 and a bottom surface 216.

As shown in FIG. 4, the light incident surface 212 of the light guide plate 210 faces the light emitting surface 252 of the light emitting diode 250. The light exit surface 214 of the light guide plate 210 is adjacent to one side of the light incident surface 212. In an embodiment, the light exit surface 214 has a sandblasted surface. In FIG. 4, the backlight module 200 is inverted to facilitate the description of its structural features. The bottom surface 216 is opposite to the light exit surface 214 and adjacent to the other side of the light incident surface 212, and has a plurality of flat regions 219 and a plurality of micro-optical structures 218. The flat zone 219 intersects the light incident surface 212 at a boundary line L. The position of the flat area 219 corresponds to the light emitting surface 252 of the light emitting diode 250 respectively; the brightness enhancing film 220 is disposed above the light emitting surface 214 of the light guide plate 210. The diffusion sheet 230 is disposed above the brightness enhancement film 220.

Referring to FIG. 5, in an embodiment, the micro-optical structure 218 of the bottom surface 216 of the light guide plate 210 may be a prismatic structure, such as a triangular prism 218a. Each of the triangular prisms 218a has a starting point 218b and an extending direction E. The starting point 218b is adjacent to the flat zone 219. The extending direction E is perpendicular to the boundary line L between the flat region 219 and the light incident surface 212, and is parallel to the bottom surface 216 of the light guide plate 210. The flat region 219 is defined by a virtual line C connecting the starting point 218b of the triangular prism 218a and a boundary line L between the flat area 219 and the light incident surface 212, defined by the virtual line C and the boundary line L. The shape of the flat zone 219, such as the flat zone 219 shown in Figure 5, is generally triangular in shape.

In an embodiment, the virtual connection of the starting point of the micro-optical structure comprises a V-shaped line segment or an irregular line segment. In one embodiment, the virtual connection of the starting point of the micro-optical structure substantially corresponds to the illuminating light field profile of each of the light-emitting diodes. In one embodiment, the shape outside each flat zone is selected from the group consisting of a rectangle, a triangle, an arch, and a half arc.

In the embodiment shown in FIG. 5, triangular prisms 218a are juxtaposed on the bottom surface 216, and a plurality of peaks 218c and a plurality of valleys 218d are formed. The flat zone 219 is at the same height as the valley 218d of the micro-optical structure 218.

The flat region 219 has a width W1 and a depth D, and the width W1 is the distance between the right edge of the leftmost micro-optical structure 218 of the flat region 219 and the left edge of the rightmost micro-optical structure 218 of the flat region 219, and the direction is parallel. At the above boundary line L. The depth D is the distance between the boundary line L and the starting point 218b of the bottom surface 216 which is the farthest from the boundary line L, and the direction thereof is perpendicular to the boundary line L. In one embodiment, the depth D is from 3 micrometers (mm) to 30 micrometers.

The light emitting surface 252 of each of the light emitting diodes 250 has a width W2, and the width W2 of the light emitting surface 252 is parallel to the boundary line L. In one embodiment, the width W1 of the flat region 219 of the light guiding plate 210 is two. The light-emitting surface 252 of the polar body 250 has a width W2 of 1.1 to 3 times.

Referring to FIG. 6, the flat region 319 of the light guide plate 310 has a sandblasted surface that is the same height as the valley portion 318d of the micro-optical structure 318, but each of the triangular prisms 318a of the present embodiment has a pyramid-shaped end portion 318E, a triangle. The starting point 318B of the prism 318a is one of the tips of the end 318E. The length L1 of the end portion 318E in the extending direction E is about 3 micrometers to 30 micrometers. In the range of the length L1, the height HI of the end portion 318E is gradually increased from the starting point 318B to the extending direction E to a predetermined height HO. In other words, the height H1 of each of the triangular prisms 318a is no longer changed after the starting point 318B is increased in the extending direction E to a predetermined height HO.

Referring to FIG. 7, in an embodiment, the micro-optical structure 418 is a V-shaped groove 418a. The V-shaped grooves 418a are arranged side by side on the bottom surface 416 of the light guide plate 410 to form a plurality of peak portions 418c and a plurality of valley portions 418d. The flat zone 419 is at the same height as the peak 418c of the micro-optical structure 418. Each V-shaped groove 418a has a starting point 418b and an extending direction E, the starting point 418b is adjacent to the flat zone 419, and the extending direction E is parallel to the bottom surface 416 and perpendicular to the boundary line L. Incidentally, in the present embodiment, the flat portion 419 of the light guide plate 410 is defined in the same manner and shape as the flat portion 219 of the light guide plate 210 of FIG. 5, and the flat portion 419 can form a sandblasted surface via surface treatment. In another embodiment, the flat zone 419 is processed into a smooth surface.

Referring to FIG. 8, in a light guide plate 510 of an embodiment, the micro-optical structure 518 is a V-shaped groove 518a. The flat zone 519 is at the same height as the peak 518d of the micro-optical structure 518, but each V-shaped groove 518a has a pyramid-shaped end 518E, and the starting point 518B of the V-shaped groove 518a is one of the tips of the end 518E. . The length L2 of the end portion 518E in its extending direction E is about 3 micrometers to 30 micrometers. In the length L2, the depth d of the end portion 518E is gradually increased from the starting point 518B to the extending direction E to a predetermined depth d0. In other words, the depth d of each of the V-shaped grooves 518a is not changed from the starting point 518B to the extending direction E to a predetermined depth d0. Incidentally, in the present embodiment, the flat region 519 of the light guide plate 510 is defined in the same manner and shape as the flat region 219 of the light guide plate 210 of FIG. The flat zone 519 has a smooth surface. In another embodiment, the flat zone 519 is processed into a sandblasted surface.

Referring to FIGS. 9A to 9D, a light guide plate 210 having a V-cut structure composed of a plurality of triangular prisms or a plurality of V-shaped grooves on the bottom surface is taken as an example. When the apex angle θ of the V-cut structure is 90 degrees, The light beam 1 incident on the light guide plate 210 includes the following four modes of transmission.

a. As shown in FIG. 9A, the incident beam I with an angle of more than 65° with the vertical axis of the light-emitting surface 214 (shown by a broken line) is twice refracted and once totally reflected by the V-cut structure, and converted to a light exit angle. The outgoing beam O, for example, has an exit angle of 22°.

b. As shown in FIG. 9B, the incident light beam I having an angle between 50° and 65° with the vertical axis of the light-emitting surface 214 (shown by a broken line) is sequentially refracted through the V-cut structure, and the lower reflection sheet 240 is sequentially rotated. The primary reflection and the Vcut structure are once refracted into the light guide plate 210, and then converted into a light exiting beam O having a small light exit angle by a total reflection of the V-cut structure, for example, the light exit angle is 35°.

c. As shown in FIG. 9C, the incident light beam I having an angle between 2° and 40° with the vertical axis of the light-emitting surface 214 (shown by a broken line) is sequentially refracted through the V-cut structure, and the lower reflection sheet 240 is sequentially rotated. After one reflection and Vcut structure is once refracted, it is converted into an outgoing beam O with a slightly smaller exit angle, for example, an exit angle of 5°.

d. As shown in FIG. 9D, the incident light beam I having an angle between 0° and 2° with the vertical axis of the light-emitting surface 214 (shown by a broken line) is twice totally reflected in the light guide plate 210, and then exits The angle is still between 0° and 2°.

Based on the above four modes, the refraction and total reflection of the V-cut structure of the light guide plate 210, together with the reflection of the reflection sheet 240, cause the exit direction of most of the incident light beam I to approach the light exit surface 214 of the light guide plate 210. The vertical direction.

Referring to FIGS. 10A and 10B, the micro-optical structure 418 of FIG. 10A is, for example, a V-shaped groove, and the micro-optical structure 218 of FIG. 10B is, for example, a triangular prism. Comparing FIG. 2 of the prior art, the light guide plate 110 of FIG. 2 is distributed near the point source 150 with a V-cut micro-optical structure 114, that is, a V-cut micro-optical structure 114 is disposed within the light-mixing region R, so the above four The light beam transmission of the mode occurs in the light mixing region R, so that the light beam entering the light guide plate 110 is deflected to an angle suitable for light output before being effectively mixed, and the light guide plate 110 is emitted to form light. point. In FIGS. 10A and 10B, flat regions 219, 419 having smooth surfaces or sandblasting and atomizing surfaces are disposed in the light mixing region R near the light incident surface 212 of the light guide plate 210, so that the light beam entering the light guide plate 210 is in the flat region 219, 419. The inside is transmitted to the farther with total reflection, and sufficient diffusion is obtained during the transfer. After the light mixing effect is achieved, the light beam is transmitted by the micro-optical structures 218, 418 in the manner shown in FIGS. 9A to 9D to change the direction in which the light beam is transmitted, and is emitted from the vertical direction of the light-emitting surface of the light guide plate 210. Thus, since the flat regions 219, 419 can reduce the chance that the light beam emitted from the light-emitting diode 250 will exit the light guide plate 210 before the light is sufficiently mixed, the light spot phenomenon can be attenuated. It is worth mentioning that, in this embodiment, the density of the sandblasting microstructure on the upper surface of the light guide plate 210 is not required to be improved, so that the light spot phenomenon can be improved, so that the halo phenomenon near the light incident surface 212 is not increased.

In another embodiment, the plurality of light-emitting diodes 250 in the backlight module 200 are all in a top view package type or a side view package type, or a part of the front side light-emitting package. The package type, while the other part uses a side-emitting package type. Different types of light-emitting diodes generally have different light field shapes or light-emitting wavelengths. One embodiment of the present invention determines the position, shape and size of the flat regions according to the position of the light-emitting diodes or the shape of the light-emitting diodes, as exemplified below.

Referring to FIGS. 11A and 11B , the LEDs 350 in the backlight modules 300 and 301 are all LEDs of the front-emitting package type or LEDs of approximately circular shape. Since the shape of the light field F1 of this type of light-emitting diode is approximately circular, in order to make the shape of the flat regions 619, 719 of the light guide plates 610, 710 match the shape of the light field F1, in an embodiment, the shape of the flat region 619 is as shown in FIG. 11A. Shown has a curved edge, or a square flat zone 719 as shown in Figure 11B, i.e., the flat zone 719 has a straight edge having a depth D dimension approximately equal to its width Wl dimension. FIG. 11A shows that in one embodiment, the flat regions 619 corresponding to the plurality of LEDs 350 are connected to each other, and the light spot can be reduced.

Referring to FIGS. 11C and 11D, the light-emitting diodes 450 in the backlight modules 400 and 401 are all light-emitting diodes of a side-emitting package type or light-emitting diodes of a substantially elliptical shape. Since the shape of the light field F2 of this type of light-emitting diode is approximately elliptical, in order to make the shape of the flat regions 819, 910 of the light guide plates 810, 910 match the shape of the light field F2, the depth D of the flat regions 819, 919 should be larger than the width W1. In an embodiment, the shape of the flat zone is an acute triangle as shown in Fig. 11C, or a rectangle as shown in Fig. 11D.

Referring to FIG. H1, in the backlight module 500, a front light emitting package type light emitting diode 350 and a side light emitting package type light emitting diode 450 are simultaneously used, and the front light emitting package type light emitting diode 350 corresponds to a first The position of the flat zone, such as flat zone 619, 719, and the side-light-emitting package type of light-emitting diode 450 correspond to the location of an elongated second flat zone, such as flat zone 819, 919. In contrast, the depth D of the first flat zone is smaller than the depth D of the second flat zone.

In an embodiment of the invention, the virtual connection of the starting point of the micro-optical structure (for example, a triangular prism or a V-shaped groove) of the bottom surface of the light guide plate corresponds to the light-emitting light field shape of the light-emitting diode. In an embodiment, the virtual connection includes a V-shaped line segment, an arc or an irregular curve, and the flat area of the bottom surface of the light guide plate is distributed in the light-mixing area near the light-incident surface of the light guide plate, and corresponds to the light-emitting diode respectively. The position of each flat zone is directly in front of the corresponding light-emitting diode. Since the flat region can reduce the chance that the light beam emitted from the light-emitting diode emits the light guide plate before the light is sufficiently mixed, the light spot phenomenon can be weakened. It is worth mentioning that, in this embodiment, the density of the sandblasting microstructure on the upper surface of the light guide plate is not required to be improved, so that the light spot phenomenon can be improved, so that the halo phenomenon near the light incident surface can be reduced.

However, the above is only the embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are still It is within the scope of the patent of the present invention. In addition, any of the objects or advantages or features of the present invention are not required to be achieved by any embodiment or application of the invention. In addition, the abstract sections and headings are only used to assist in the search of patent documents and are not intended to limit the scope of the invention.

<p>100. . . Conventional edge-lit backlight module</p><p>110. . . Light guide</p><p>112. . . Sandblasted microstructure</p><p>114. . . V-cut micro-optical structure</p><p>120. . . Reverse film</p><p>130. . . Diffusion sheet</p><p>140. . . Reflective plate</p><p>150. . . point Light</p><p>152. . . Reflector</p><p>R. . . Mixed light area</p><p>200,300,301,400,401,500. . . Sidelight backlight module</p><p>210,310,410,510,610,710,810,910. . . Light guide</p><p>212. . . Light-incident surface of the light guide plate</p><p>214. . . Light exit surface of the light guide plate</p><p>216,416. . . Bottom of the light guide plate</p><p>218,318,418,518. . . Micro-optical structure</p><p>218a, 318a. . . Triangular prism</p><p>218b, 318B, 418b, 518B. . . Starting point</p><p>218c, 418c, 518d. . . Peak of micro-optical structure</p><p>218d, 318d, 418d. . . Valley of micro-optical structures</p><p>219,319,419,519,619,719,819,919. . . Flat zone</p><p>220. . . Brightening film</p><p>230. . . Diffusion sheet</p><p>240. . . Reflective plate</p><p>250. . . Light-emitting diode</p><p>252. . . Luminous surface of a light-emitting diode</p><p>318E. . . Angled end of a triangular prism</p><p>418a, 518a. . . V-groove</p><p>518E. . . Tapered end of a V-shaped groove</p><p>350. . . Front light emitting package type light emitting diode</p><p>450. . . Side-emitting package type light-emitting diode</p><p>F1. . . Light field of a light-emitting diode of a front light-emitting package type</p><p>F2. . . Light field of a light-emitting diode of a side-emitting package type</p><p>C. . . Virtual connection</p><p>L. . . Junction line</p><p>W1. . . Width of the flat zone</p><p>D. . . The depth of the flat zone</p><p>W2. . . Width of the light emitting surface of the light emitting diode</p><p>L1. . . Length of the end of the triangular prism</p><p>H1. . . Height of the end of the triangular prism</p><p>H0. . . The predetermined height of the triangular prism</p><p>L2. . . Length of the end of the V-shaped groove</p><p>d. . . Depth of the end of the V-shaped groove</p><p>D0. . . The predetermined depth of the end of the V-shaped groove</p>

FIG. 1 is a schematic diagram of a conventional edge-lit backlight module.

2 is a schematic diagram of a beam transfer path of a conventional edge-lit backlight module.

FIG. 3A is a schematic diagram of a light spot phenomenon of a conventional edge-lit backlight module.

FIG. 3B is a schematic diagram of a halo phenomenon of a conventional edge-lit backlight module.

4 is a schematic diagram of an edge-lit backlight module according to an embodiment of the invention.

5 to 8 are schematic views showing the structure of a light guide plate according to an embodiment of the present invention.

9A and 9D are schematic diagrams showing a beam transfer mode of a light guide plate according to an embodiment of the present invention.

10A and 10B are schematic diagrams showing a beam transmission path of an edge-lit backlight module according to an embodiment of the invention.

11A-11E are schematic diagrams showing the position and shape of a flat region of a light guide plate according to an embodiment of the present invention.