TW201102720A - Backlight module - Google Patents

Abstract

A backlight module including a light guide plate and a plurality of luminous elements is provided. The light guide plate has an incident surface and an emitting surface, wherein the emitting surface has a view area. The luminous elements are disposed on the incident surface of the light guide plate, wherein each of the luminous elements has a light emitting surface and an optical axis perpendicular to the light emitting surface. The axes are substantially intersected at a central point of the view area.

Description

201102720 AU0811035 30932twf.doc/n VI. Description of the Invention: [Technology of the Invention] The present invention relates to a backlight module and particularly relates to a backlight module which can improve overall brightness. [Prior Art] In general, a liquid crystal display device generally includes a liquid crystal display panel and a backlight module. The backlight module is mainly used to provide a surface light source required for the liquid crystal display panel to display. 1 is a schematic plan view of a conventional backlight module. For convenience of description, FIG. 1 only shows the relative position of the light-emitting diode and the light guide plate in the backlight module, and does not show the optical film located under the light guide plate. sheet. Please refer to FIG. 1 'The backlight module 100 includes a plurality of light emitting diodes u and a light guide plate 120. The light guide plate 120 has a long side and a short side, and the light emitting diode is usually arranged on the long side or the short side of the light guide plate 12 以 as a light source of the backlight "module 100, wherein FIG. 1 shows the light emitting diode 110 is arranged on the short side of the guide plate 120, in other words, the short side is the ~122 of the light guide plate 12''. The illuminating surface of each of the illuminating diodes 110 has a light emitting surface 112 and an optical axis 114 of 112. In detail, the arrangement pattern 35 of the short sides of the light-emitting diode 110 with the light 1612G is often linearly parallel, that is, the light 2 of each of the light-emitting diodes 11 is flat: As shown in FIG. 1 , the illumination angle of the light-emitting diode 110 is usually about 110 degrees, and the arrangement of the 201102720 AU0811035 30932 twf.doc/n light-emitting diode 110 on the short side of the light guide plate 120 is as shown in FIG. 1 . The number of times of the light provided by the light-emitting diode 11 于 in the light guide plate is reduced, and the light path incident on the light guide plate 12 易于 is also easy to scatter the light guide plate 12 随着 as it approaches the edge of the light guide plate 120 . Further, the light utilization efficiency of the light-emitting body 110 is lowered. As a result, the overall brightness of the backlight module 100 will not be easily improved. SUMMARY OF THE INVENTION In view of the above, the present invention provides a backlight module that can concentrate light incident on a light guide plate and enhance the number of times of light refraction in the light guide plate, and has better overall brightness. The invention provides a backlight module comprising a light guide plate and a plurality of light emitting elements. The light guide plate has a light incident surface and a light exit surface, wherein the light exit mask has a visible area. The light emitting elements are disposed on the light incident surface of the light guide plate, wherein each of the light emitting elements has a light emitting surface and an optical axis perpendicular to the light emitting surface. These optical axes generally intersect at the center point of the viewable area. In an embodiment of the invention, an odd number of light-emitting elements are disposed on the light-incident surface of the light guide plate. In an embodiment of the invention, the viewable area has a width X in the horizontal direction and a length Y in the vertical direction. An angle between the optical axis of each of the light-emitting elements and the vertical direction of the visible region is 0 〇 1 is: I (2n + l) Y f where 'the light-emitting surface of the light guide plate is provided with 2n + 1 light-emitting elements, and η pregnancy 0, m is a positive integer of 〇~n, and _1<σ<1. 201102720 AU0811035 30932twf.doc/n In one embodiment of the invention, the viewable area has a width X in the horizontal direction and a length γ in the vertical direction. The viewable area has a center line in the vertical direction, and a distance dm between each of the light-emitting elements and the center line in the horizontal direction is: ',

2a\ Y / (m + σ)

X 2n + l

Wherein the light-incident surface of the light guide plate is provided with 2η+1 light-emitting elements, n ping 0, m is a positive integer of 0~η, a is the distance from the light-incident surface of the light guide plate to the edge of the visible area, and -0.5 <σ<0.5. In an embodiment of the invention, an even number of light-emitting elements are disposed on the light-incident surface of the light guide plate. In one embodiment of the invention, the viewable area has a width X in the horizontal direction and a length 垂直 in the vertical direction. An angle between the optical axis of each of the light-emitting elements and the vertical direction of the visible area is: Θ tan

{{2m -1) + σ) ΧΥηΫ wherein the light-incident surface of the light guide plate is provided with 2n light-emitting elements, and η #0,m is a positive integer ' of 1 to η and -0.5 < σ < 0.5. In one embodiment of the invention, the viewable area has a width X in the horizontal direction and a length Υ in the vertical direction. The viewable area has a center line in the vertical direction, and a distance between each of the light-emitting elements and the center line in the horizontal direction is: 201102720 AUU8U035 30932twf.d〇c/n + —1) + σ) goes to I, and ' In the US, the light-emitting surface of the light guide plate is provided with 2n light-emitting elements, and 0 'm is a positive integer of 1 to η' a is the distance from the light-incident surface of the light guide plate to the edge of the visible area, and -l<cr<lt;;l. In one embodiment of the invention, the light guide plate has a plurality of grooves on the light incident surface, and a light emitting element is placed in each of the grooves. In an embodiment of the invention, the viewable area has a centerline in the vertical direction, the grooves each having an oblique angle, and the closer to the groove of the center line of the light guide plate, the smaller the inclination angle. In an embodiment of the invention, the backlight module further includes an optical film set and a reflective sheet. The optical film set is disposed above the light exit surface of the light guide plate. The reflective sheet is disposed on a surface of the light guide plate facing the light-emitting side. Based on the above, the backlight module of the present embodiment adopts the above formula to illuminate by making the optical axis of each light-emitting element intersect at the center point of the visible area and matching the number of light-emitting elements (such as an odd number or an even number). The component is disposed on the light incident surface, so that the overall brightness of the light exit surface of the light guide plate can be improved, thereby enabling the backlight module to provide a backlight with better brightness. The above described features and advantages of the present invention will become more apparent from the description of the appended claims. 2A is a top plan view of a backlight module according to an embodiment of the present invention, and FIG. 2B is a cross-sectional view of the backlight module taken along line AA of FIG. 2A. 201102720 AUU8 i 1U35 30932twf.doc/n For convenience of explanation, FIG. 2A only shows the relative positions of the light-emitting elements of the backlight module and the light guide plate, and does not show the diaphragm located under the light guide plate. Referring to FIG. 2A and FIG. 2B, the backlight module 200 of the embodiment includes a light guide plate 210 and a plurality of light emitting elements 220. The light guide plate 210 has a light incident surface 212 and a light exit surface 214, wherein the light exit surface 214 has a visible area 214a. The light-emitting elements 220 are disposed on the light-incident surface 212 of the light guide plate 210. Each of the light-emitting elements 220 has a light-emitting surface 222 and an optical axis 224 ′ perpendicular to the light-emitting surface 222 and the optical axes 224 substantially intersect with the visible area. Center point C1 of 214a. In the present embodiment, the light from the light-emitting element 220 is adapted to be incident from the light-incident surface 212 to the inside of the light guide plate 210, and is repeatedly refracted therein and then emitted from the light-emitting surface 214. In addition, the light-emitting element 220 is, for example, a light-emitting diode, and the type of the light-emitting diode may be side-emitting or top-emitting, depending on the design and needs of the user. Further, the plurality of light rays emitted from the light-emitting element 220 are usually mostly the light-emitting surface 222' of the vertical light-emitting element 22, wherein the light-emitting surface 222 is located at the position where the light intensity is the strongest, and is often referred to as the optical axis. Therefore, the optical axis 224 of the present embodiment can be defined as the central position of the light emitting surface 222. In this embodiment, an odd number of light emitting elements 220 are disposed on the light incident surface 212 of the light guide plate 210, as shown in FIG. 2A. In detail, 2n+1 light-emitting elements 220 are disposed on the light incident surface 212 of the light guide plate 210, and η is an integer greater than zero. Further, the visible area 214a has a width X in the horizontal direction pi and a length γ in the vertical direction P2. In this embodiment, between the optical axis 224 of each of the light-emitting elements 220 and the vertical direction P2 of the visible region 214a, 201102720 AUU511035 30932 twf.doc/n I, has an angle, wherein the angle 0m is defined as: em= tan-1 ( 2η +1) Υ m is an integer of 0 to η, and -1 < σ < In addition, it should be noted that, Θ. Representing the angular position between the optical axis of the light-emitting element 220 located at the middle of the plurality of light-emitting elements 22A and the vertical direction ρ2 of the visible area 214a. In addition, the visible area 214a has a center line u in the vertical direction Ρ2. and has a distance dm between the light-emitting element 22() and the center line u in the horizontal direction P1, where dm is defined as: dm = 1 2a\ Ύ {m + σ) X 2n + \ m is a positive integer of 0~n, _〇.5<σ<〇5, and a is defined as the entrance surface of the light guide plate 21 to the edge of the visible area pool The distance from here to the light surface 212 refers to the plane of the edge of the parallel viewable area 214a. According to the above configuration, if the width X is smaller than the length γ, the light-emitting element 220 is incident on the short side of the light guide plate 210, and the light-emitting element 22 is disposed on the light-incident surface 212 of the light guide plate 210 by the above-described conditions. The number of refractions of the light provided by the light-emitting element 22〇 in the light guide plate 21〇 can be increased. In the case where the width χ is less than the length γ, the arrangement of the light-emitting elements 220_ can increase the number of times of refraction of the light rays continuing inside the light guide plate 210, and at least compared with the configuration using the prior art. Can be increased to 8.1%. In addition, if the width X is greater than the length γ, the thief-table light-emitting element 22 is incident on the long side of the lead-plate 210, and similarly, if the light-emitting element 22 is used in 201102720 AUU611U35 30932 twf.doc/n, the above-mentioned strip is placed on the light guide plate. When the 21G ό illuminating surface 212 is incident on the light-refraction slit of the portion of the light guide plate 2, it can be raised to at least 5〇9% or more compared with the conventional technique. In other words, regardless of whether the light provided by the light-emitting element 220 is incident from the long side or the short side of the 21 ' 'as long as the optical axis of each of the light-emitting elements 22 seems to substantially intersect at the center point C1 of the visible area 214a, and each A illuminating element can be disposed on the light incident surface X2u of the light guide plate 21〇 by the above-mentioned conditions.

The number of refractions of the light inside the light guide plate 21 can be increased, thereby increasing the overall brightness of the light surface 214. In addition, the concept of the arrangement of the optical axis 222 of the light-emitting element 22 is substantially intersected, and the problem of bright and dark bands around the visible area 214a of the light guide plate can be effectively improved, the difference between the bright and dark bands can be reduced, and the light uniformity can be improved. Sex. In the present embodiment, the light incident surface 212 of the light guide plate 210 has a plurality of grooves 216' and a light-emitting element '22' is placed in each of the grooves 216 as shown in the figure. Wherein these grooves 216 have an oblique angle (not shown) and are closer to the center line of the light guide plate 210! The smaller the inclination angle of the groove 216 is. The angle of the inclination angle may be substantially the same as the angle described above. The groove 216 can be used as a light-emitting element 22 to assemble and position. In addition, the backlight module 200 further includes an optical film set 23A and a reflective sheet 240, as shown in FIG. 2B. In this embodiment, the optical film group 230 is disposed above the light-emitting surface 214 of the light guide plate 210, and the reflective film 24 is disposed on the opposite surface of the light-emitting surface 214 of the light guide plate 210. The optical film set 230 can be at least one of a diffusion sheet, a brightness enhancement sheet, a uniform sheet, and a composite optical sheet. In addition, the light guide plate 21 of the present embodiment is described by the example of the wedge-shaped light guide plate 201102720 11〇35 30932tvvf.doc/n, but the present invention is not limited to such a light guide plate. FIG. 3 is a schematic top view of a backlight module according to another embodiment of the present invention. Similarly, for convenience of explanation, FIG. 3 only shows the relative positions of the light-emitting elements of the backlight module and the light guide plate, and does not show the diaphragm located under the light guide plate. Referring to FIG. 2A and FIG. 3 simultaneously, the backlight module 3 of the present embodiment is similar to the backlight module 200, but the difference is that the arrangement of the light-emitting elements 210 of the backlight module 3 is slightly different from that of the backlight module. Group 200, which is described in detail below.

In the backlight module 300, an even number of light-emitting elements 220 are disposed on the light-incident surface 212 of the light guide plate 210, as shown in FIG. In detail, 2n light-emitting elements 220 are disposed on the light incident surface 212 of the light guide plate 210, and η is a positive integer greater than zero. Further, the visible area 214a has a width X in the horizontal direction Ρ1 and a length Y in the vertical direction P2. In this embodiment, the optical axis 224 of each of the light-emitting elements 220 has an angle 0m between the vertical direction P2 of the visible region 214a, wherein the angle 0m of the embodiment is defined as ((2m -1) + σ) Χ, θ tan 丨

2nY and

m is a positive integer of 1 to n, and -0.5 < σ < 0.5 Similarly, the visible region 214a has a center line L1 in the vertical direction Ρ2, and between each of the light-emitting elements 220 and the center line L1 in the horizontal direction pi There is a distance (^, wherein the dm of the embodiment is defined as: and m is a positive integer of 1 to n, and a is the distance from the light incident surface 212 of the light guide plate 210 to the edge of the visible region 214a, where the light is incident. 212 finger 疋 parallel 10 201102720 八 UUSUU35 30932 twf.d 〇 c / n The plane of the edge of the visible area 214a, and _1 < σ < 1. According to the above, 'the number of light-emitting elements 220 of the backlight module 300 is an even number' Therefore, the condition that the light-emitting element 220 is disposed on the light-incident surface 212 is also changed, for example, an angle of 0 m, a distance 屯, etc., and although the angle 6 > m and the distance dm are adjusted according to the number of the light-emitting elements 220, 'As with the above backlight module 2', the optical axis 224 of each of the light-emitting elements 220 is also substantially intersecting at the center point C1 of the visible area 214a, φ as shown in Fig. 3. In other words, the backlight mode of the present embodiment The group 30 〇 and the backlight module 200 are only different in number of the light-emitting elements 220 The parameter conditions (such as the angle and the distance dm) of the light-emitting element 22 disposed on the light-incident surface 212 may be slightly adjusted according to the number of the light-emitting elements 220 by an odd number or an even number, so the backlight mode of the embodiment The group 300 also has the advantages mentioned in the backlight module 200, and will not be described herein. The backlight module of the present invention has at least the following advantages. First, the optical axis of each of the light-emitting elements will be substantially Intersecting at the center point of the visible area, the light provided by the illuminating element is concentrated in the visible area, thereby increasing the overall brightness of the illuminating surface, and the light provided by the illuminating part at the edge of the light guiding plate is also higher. It is not easy to scatter the light guide plate. In addition, for different numbers of light-emitting elements (such as odd or even number), the light-emitting elements are set, and the parameter conditions (such as the angle 0m and the distance dm) on the light-incident surface can also be adjusted and adjusted. In order to improve the refraction frequency of the light incident on the light guide plate, the overall brightness of the backlight module can be further improved. In addition, the brightness of the visible area can be improved due to uneven distribution of the light source. Dark band phenomenon. 11 201102720 AUOSU035 30932 twf.d〇c/n Although the present invention has been disclosed above by way of example, it is not intended to limit the invention, and any one of ordinary skill in the art will not be able to In the spirit and scope, when a little change and refinement can be made, the scope of protection of Benming is subject to the definition of the patent application scope attached. [Simplified illustration] Figure 1 is a conventional backlight module. 2A is a top plan view of a backlight module according to an embodiment of the invention. 2B is a cross-sectional view of the backlight module taken along line AA' of FIG. 2A. FIG. 3 is a schematic top view of a backlight module according to another embodiment of the present invention. [Main component symbol description] 100, 200, 300: backlight module 110: LEDs 120, 210: light guide plates 122, 212: light incident surfaces 112, 222: light emitting surfaces 114, 224: optical axis 214: light output Face 214a: viewable area 216: groove 220: light-emitting element 230: i-slice diaphragm group 201102720 AUU<SII035 30932twf.doc/a 240: reflection sheet C · center point PI: horizontal direction P2 · vertical direction LI: center line X : Width Y : Length dm : Distance 6» m : Angle

Claims (1)

201102720 Λυυ» 1 i 035 30932twf.doc/n VII. Patent application scope: 1. A backlight module comprising: a light guide plate having a light incident surface and a light exit surface, wherein the light exit mask has a visible area; And a plurality of light emitting elements disposed on the light incident surface of the light guide plate, wherein each of the light emitting elements has a light emitting surface and an optical axis ' perpendicular to the light emitting surface, and the optical axes substantially intersect the visible light The center point of the district. 2. The backlight module of claim 1, wherein the light incident surface of the light guide plate is provided with an odd number of light emitting elements. 3. The backlight module of claim 2, wherein the vehicular region has a width — in the horizontal direction and a length in the vertical direction ′ an optical axis of each illuminating member and a vertical direction of the visible region There is a missing angle between 0„1: / 0m = tan' (2ιη + σ)χ)T^iTflyv7 where 'the light guide plate is provided with 2n+l light-emitting elements' and #〇, m is an integer of 0 to η, and is a lion of the (4) lion, wherein the lion can have a straight direction, and the 丄-direction mother-first member has a distance from the center line. The heart is: 201102720 auusu035 30932twf.doc/n 2a Y where 'the light guide plate is provided with a number of elements such as +丨, βΟ ' m is an integer of 0~n, and a is the input surface of the light guide plate The distance to the edge of the viewable area, and _〇.5<σ<〇5. 5. The backlight module of claim 1, wherein the light incident surface of the light plate is provided with an even number of light emitting elements. 6. The backlight module of claim 5, wherein the viewing zone has a width in the horizontal direction and a length in the money direction. The optical axis of each of the J elements is perpendicular to the visible area. The direction of "one angle, poor tan tan?, two Hj · σ) Χ 2ηΥ and 〇m Ο Ο where the light side of the light plate is found with % light-emitting elements, m is a positive integer from 1 to η And a backlight module according to the fifth aspect of the invention, wherein the Χ; Χ and (4) the new direction has a length center, and the second viewing zone has a center line in the vertical direction, and In the horizontal direction, there is a distance dm between the female 兀 与 and the center line: 15 201102720 AUU811035 30932twf.doc/n dm=\ 1 + —^((2m-l) + a)—I , jl dm^ 0, wherein the light-incident surface of the light guide plate is provided with 2n light-emitting elements, and η 4 0 'm is a positive integer of 1 to η' a is the distance from the light-incident surface of the light guide plate to the edge of the visible region The backlight module of claim 1, wherein the light guide plate has a plurality of grooves on the light incident surface, A light-emitting element is disposed in each of the grooves. The backlight module of claim 8, wherein the visible area has a center line in a vertical direction, and the grooves respectively have an inclination angle. The slanting angle of the groove of the center line of the light guide plate is smaller. 10. The backlight module of claim 1, further comprising: an optical film set disposed on the light guide plate Above the light-emitting surface; and a reflective sheet disposed on the surface of the light guide plate facing the light-emitting side.