TWI729839B - Light guide plate, backlight module and display device - Google Patents

Abstract

A light guide plate includes a light-emitting surface. The light-emitting surface includes a convex lens, a plurality of first microstructures and a plurality of second microstructures. The convex lens is located at a center of the light-emitting surface. The first microstructure is an annular structure. The plurality of the first microstructures are concentric and disposed around the convex lens. The second microstructure is an arc structure and is disposed around the plurality of the first microstructures. Each of the first microstructure and the second microstructure has a refractive surface for refracting a light ray passing therethrough. A plurality of elongated protrusion structures are at least disposed on the refractive surface of the second microstructure located at the outermost of the light-emitting surface.

Description

Light guide plate, backlight module and display device

The present invention relates to a light guide plate, a backlight module and a display device, and more particularly to a light guide plate with good optical taste, and a backlight module and a display device using the light guide plate.

Light Emitting Diode (LED) has become the mainstream of the backlight source of liquid crystal displays (LCD) due to its small size, environmental protection, and long life. Since the LED has the luminous characteristics of a point light source, there is a problem of uneven luminous intensity.

Please refer to FIG. 1, which is a schematic diagram of the appearance of the light guide plate 10 of the conventional LCD. The light guide plate 10 includes a light emitting surface 11, which can be divided into an active area (AA) 11a and a mixing area 11b according to functional characteristics. The frame 13 includes a lower frame 13a, and LEDs (not shown) are arranged On one side of the light guide plate 10, the light emitted by the LED enters the light mixing area 11b of the light guide plate 10, and after the light is homogenized, the light is emitted from the effective area 11a. The effective area 11a corresponds to the visible range of the conventional LCD. In order to make the effective area 11a meet the requirements of uniform brightness, it is usually necessary to configure a sufficient light mixing distance C1. The longer the light mixing distance C1, the lower the ratio of the effective area 11a on the light exit surface 11, which is the LCD screen ratio. The lower. Generally, the sum of the mixing distance C1 and the length C2 of the lower border 13a is called the Bo (Border) value (ie Bo=C1+C2, defined as the distance from the side wall to the visible range), and the Bo value can be used as the screen ratio Indicator, the lower the Bo value, the The higher the screen ratio.

In order to meet the current market demand, how to develop an LCD with a high screen-to-body ratio and uniform light output is the goal of the relevant industry.

The purpose of the present invention is to provide a light guide plate, a backlight module and a display device to solve the above-mentioned problems.

According to one embodiment of the present invention, a light guide plate is provided, which includes a light-emitting surface. The light-emitting surface includes a convex lens, a plurality of first microstructures and a plurality of second microstructures. The convex lens is located at the center of the light-emitting surface. The first microstructure is a ring structure, and a plurality of first microstructures are concentric with each other and surround the periphery of the convex lens. The second microstructure is an arc-shaped structure and surrounds the periphery of the plurality of first microstructures. Both the first microstructure and the second microstructure have a refractive surface for deflecting and permeating a light, and at least a plurality of strip-shaped protrusion structures are provided on the refractive surface of the second microstructure located at the outermost side.

According to another embodiment of the present invention, a backlight module is provided, which includes the aforementioned light guide plate.

According to another embodiment of the present invention, a display device is provided, which includes the aforementioned backlight module and a display panel, and the display panel is disposed above the backlight module.

Compared with the prior art, the light guide plate of the present invention is provided with a convex lens, a plurality of first microstructures and a plurality of second microstructures on the light-emitting surface, which can increase the directivity and uniformity of the emitted light. The shaped protrusion structure is beneficial to prevent dark corners from appearing in the peripheral area, and can improve the uniformity of light output, and complete a backlight module or display device with a small light mixing area and a high screen ratio.

10,100: light guide plate

20: Backlight module

30: display device

11: Light emitting surface

11a: effective area

11b: mixing zone

13: Border

13a: bottom border

110: Glossy Surface

111: Central District

112: Peripheral area

121: Convex lens

122, 122a, 122b, 122c: the first microstructure

123: The second microstructure

124: Striped protrusion structure

130: Glossy surface

140: Structure Department

141: The first light incident microstructure

142, 142a, 142b, 142c: second light incident microstructure

143: Outside

144: Inside

150: Bottom

200: light source module

210: light source

300: display panel

A, B: Part

Bo: the sum of the mixing distance and the length of the lower frame

C1: mixing distance

C2: length

D1: first side length

D2: second side length

D3: The third side length

E: arc edge

E1, E2: extension direction

L: light

P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13: points

S, S1, S2, S3: refractive surface

T, T1, T2, T3: refractive surface

Figure 1 is a schematic diagram of the appearance of a light guide plate of a conventional liquid crystal display.

Fig. 2 is a top view of a light guide plate according to an embodiment of the present invention.

Figure 3 is a partial enlarged view of part A in Figure 2.

Figure 4 is a perspective schematic view of part A in Figure 2.

Fig. 5 is a cross-sectional view of part B in Fig. 2 along the cutting plane line 4-4.

Fig. 6 is a schematic cross-sectional view of the structure in Fig. 4;

FIG. 7 is a three-dimensional schematic diagram of a backlight module according to another embodiment of the present invention.

FIG. 8 is a three-dimensional schematic diagram of a display device according to still another embodiment of the present invention.

Fig. 9 is a simulated light field distribution diagram of the conventional backlight module of the comparative embodiment.

FIG. 10 is a simulated light field distribution diagram of a backlight module according to another embodiment of the present invention.

The foregoing and other technical content, features and effects of the present invention will be clearly presented in the following detailed description of the preferred embodiment with reference to the drawings. The directional terms mentioned in the following embodiments, for example: up, down, left, right, front, back, bottom, top, etc., are only directions for referring to the attached drawings. Therefore, the directional terms used are for illustration, not for limiting the present invention. In addition, in the following embodiments, the same or similar elements will use the same or similar reference numerals.

In the present invention, the light guide plate can be used for the backlight module, and the backlight module can be used to provide a liquid crystal display (Liquid Crystal Display, LCD) panel light source, each element in the backlight module includes a bottom surface and a top surface. The definition of the bottom surface and the top surface is based on the LCD panel, and the side far away from the LCD panel is the bottom surface. , With the side facing the LCD panel as the top surface. In the present invention, the center refers to the relative center as viewed from the integral part, and does not refer to the absolute position.

Please refer to FIGS. 2 and 5. FIG. 2 is a top view of the light guide plate 100 according to an embodiment of the present invention, FIG. 5 is a cross-sectional view of part B in FIG. 2 along the secant line 4-4, and FIG. In the figure, in order to avoid interference between the hatching and the light L, the hatching is omitted. The light guide plate 100 includes a light emitting surface 110. The light-emitting surface 110 includes a convex lens 121, a plurality of first microstructures 122 and a plurality of second microstructures 123. The convex lens 121 is located at the center of the light-emitting surface 110. For example, it may be located at the center relative to the active area (AA) and the visual area (VA) of the display device applied. The first microstructure 122 is a ring structure, and a plurality of first microstructures 122 are concentric with each other and surround the periphery of the convex lens 121. The second microstructure 123 is an arc-shaped structure that also surrounds the convex lens 121 and/or the periphery of the first microstructure 122. On the light-emitting surface 110 of the light guide plate 100 of this embodiment, convex lenses 121, The first microstructure 122 surrounding the convex lens 121 and the second microstructure 123 surrounding the plurality of first microstructures 122 form a concentric microstructure pattern. Each of the first microstructures 122 and each of the second microstructures 123 has a refractive surface S for deflecting and transmitting a light L (see FIG. 5). Please refer to Figures 3 and 4 at the same time. Figure 3 is a partial enlarged view of part A in Figure 2, and Figure 4 is a perspective view of part A in Figure 2, as shown in Figures 3 and 4. A plurality of strip-shaped protrusion structures 124 are provided at least on the refractive surface S of the second microstructure 123 located at the outermost side. In addition, for the sake of brevity, the strip-shaped protrusion structure 124 is omitted in FIG. 2 and only shown in FIG. 3 and FIG. 4.

Please refer to FIG. 5, which depicts the convex lens 121 and the three first microstructures 122 adjacent to the convex lens 121. The first microstructures 122a, 122b, and 122c are formed from the inside to the outside, and the first microstructures 122a, 122b, The refraction surface S of 122c is sequentially refraction surfaces S1, S2, S3. The inclination degrees of the plurality of refraction surfaces S1, S2, and S3 are different from each other, and the inclination degree of the plurality of refraction surfaces S1, S2, and S3 is determined by the inclination of the light exit surface 110. The inner part gradually increases toward the outer part of the light-emitting surface 110. Fig. 5 takes part B of the light guide plate 100 as an example. As for the light guide plate 100 as a whole, in the first microstructure 122 and the second microstructure 123 of the light emitting surface 110, one of the plurality of refraction surfaces S The degree of inclination may be different from the degree of inclination of the other of the plurality of refraction surfaces S. Preferably, the degree of inclination of the plurality of refraction surfaces S gradually changes from the inside of the light-emitting surface 110 to the outside of the light-emitting surface 110, and the plurality of refraction surfaces S The degree of inclination of the surface S can gradually increase from the inside of the light-emitting surface 110 to the outside of the light-emitting surface 110. In this embodiment, the refraction surface S (S1, S2, S3) is a plane, however, the present invention is not limited to this. In other embodiments, the refraction surface S (S1, S2, S3) may also be a curved surface For example, it may be similar to the convex lens 121, which is a convex curved surface.

More specifically, the convex lens 121, the plurality of first microstructures 122, and the plurality of second microstructures 123 cooperate with each other to have the characteristics of a convex lens, that is, the convex lens 121, the plurality of first microstructures 122, and the plurality of second microstructures 123 The three can be regarded as a convex lens, which will be referred to as an integral convex lens below to separate it from the convex lens 121. According to the spectroscopist's formula, as shown in formula (I):

In formula (I), f is the focal length of the lens, n is the refractive index of the lens material, n _m is the refractive index of the material surrounding the lens, R ₁ is the radius of curvature of the side surface of the lens close to the light source, and R ₂ is the lens The radius of curvature of the surface away from the light source. Applying formula (I) to the integral convex lens, the curvature radius of the integral convex lens facing the bottom surface 150 of the light guide plate 100 (see Figure 4) is R ₁ , and the curvature radius of the integral convex lens facing outward is R ₂ , which can be By adjusting the values of R ₁ and R ₂ , the light L transmitted from the light emitting surface 110 is parallel light. For example, when R ₁ = R ₂ ≒ 0.3mm, f is infinite, and the overall convex lens is a parallel light The lens thereby facilitates the directivity and uniformity of the emitted light.

In detail, as shown in FIGS. 2 to 4, each of the first microstructures 122 and each of the second microstructures 123 has an arc edge E, each of the strip-shaped protrusion structures 124 is arc-shaped, and each of the strip-shaped protrusion structures An extension direction E2 of the 124 is substantially the same as an extension direction E1 of the arc edge E.

As shown in FIGS. 2 to 4, the light-emitting surface 110 may have a central area 111 and a peripheral area 112 located at the periphery of the central area 111, and the refractive surface S of the second microstructure 123 of the peripheral area 112 is provided with a strip-shaped protrusion structure 124; For example, the peripheral area 112 may be adjacent to the side of the light guide plate 100 where no light source is provided. In this embodiment, the central area 111 covers a wider area, and the peripheral area 112 only includes the second microstructure 123. However, the present invention is not limited to this. In other embodiments, the central area 111 may cover a wide range. Reduced so that the peripheral region 112 includes the first microstructure 122 and the second microstructure 123 at the same time. At this time, the refractive surface S of the first microstructure 122 and the second microstructure 123 of the peripheral region 112 is provided with a strip-shaped protrusion structure 124 . In addition, when a part of the same first microstructure 122 or the same second microstructure 123 falls on the central area 111 and the rest falls on the peripheral area 112, it can only fall on the refraction surface S of the remaining part of the peripheral area 112. A protruding structure 124 is provided, as shown in FIG. 3. The strip-shaped protrusion structure 124 can diverge the light L. By disposing the strip-shaped protrusion structure 124 in the peripheral area 112, it is beneficial to prevent dark corners from appearing in the peripheral area 112, and can further improve the light output uniformity of the light guide plate 100.

Please refer to Figure 2, the peripheral area 112 has a first side length D1 and a second side length D2, the central area 111 has a third side length D3, in terms of the side length of one side of the light guide plate 100, the side of the side The length is the sum of the aforementioned first side length D1, the second side length D2, and the third side length D3, where the sum of the first side length D1 and the second side length D2 accounts for the side length (D1+D2+D3) The ratio can be greater than 0% and less than or equal to 10%, so that, on the one hand, it can prevent vignetting in the peripheral area 112, and on the other hand, it can maintain the light L transmitted from the light-emitting surface 110. Collimation improves the frontal brightness.

As shown in FIG. 4, the light guide plate 100 may further include a light incident surface 130, and the light incident surface 130 is connected to the light output surface 110. The light incident surface 130 includes a plurality of structural parts 140, and each structural part 140 is formed with a plurality of light incident microstructures, namely, a first light incident microstructure 141 and a second light incident microstructure 142, and the first light incident microstructure 141, the second light incident microstructure 142 The two light-incident microstructures 142 are used to diverge the light entering the light-incident surface 130. Please also refer to FIG. 6, which is a schematic cross-sectional view of the structural part 140 in FIG. 4. For the sake of brevity, the hatching is omitted. In detail, the structure portion 140 includes a first light incident microstructure 141 at the center and a plurality of second light incident microstructures 142 surrounding the first light incident microstructure 141. The first light incident microstructure 141 may be one With a concave lens, the second light-incident microstructure 142 may be a ring structure or an arc-shaped structure. Here, the arc-shaped structure is taken as an example, and a plurality of second light-incident microstructures 142 are concentric with each other.

Each second light-incident microstructure 142 includes a refractive surface T. For clarity of description, the three second light-incident microstructures 142 next to the first light-incident microstructure 141 in Figure 6 are separately labeled, from the inside to the outside. The second light-incident microstructures 142a, 142b, 142c, and the refractive surfaces T of the second light-incident microstructures 142a, 142b, 142c are sequentially refraction surfaces T1, T2, T3, and the degree of inclination of the plurality of refraction surfaces T1, T2, and T3 They are different from each other, and the inclination of the plurality of refractive surfaces T1, T2, T3 gradually increases from the inside to the outside. As for the structure part 140 as a whole, in the plurality of second light incident microstructures 142, the inclination degree of one of the plurality of refractive surfaces T may be different from the inclination degree of the other of the plurality of refractive surfaces T, preferably , The degree of inclination of the plurality of refraction surfaces T gradually changes from the inside to the outside, and the degree of inclination of the plurality of refraction surfaces T can gradually increase from the inside to the outside. In this embodiment, the refraction surface T (T1, T2, T3) is a curved surface, and similar to the first light-incident microstructure 141, is an inwardly concave curved surface. However, the present invention is not limited to this. In other embodiments, the refractive surface T (T1, T2, T3) may also be a plane.

More specifically, the first light incident microstructure 141 and the plurality of second light incident microstructures 142 can be matched with each other to have the characteristics of a concave lens, that is, the first light incident microstructure 141 and the plurality of second light incident microstructures 142 are combined The formed structure part 140 can be regarded as a concave lens as a whole. The 140, the radius of curvature of the outer structure 140 portion 143 in the above formula (I) is applied to the structural unit R _1, the radius of curvature of the inner structure 140 portion 144 is R _2, may be formulated by the value of R ₁ and R _2, Let the light entering the structural part 140 from the outer side 143 and passing through the inner side 144 be divergent light, for example, when R ₁ =infinity, R ₂ =0.5 mm , f is a negative value, and the structural part 140 is a divergent light lens Therefore, it is advantageous for the light to enter the corners of the light guide plate 100 to increase the energy distribution area, so as to further improve the uniformity of the light.

Please refer to FIG. 7, which is a three-dimensional schematic diagram of a backlight module 20 according to another embodiment of the present invention, and only a part of it is shown here. The backlight module 20 includes a light guide plate 100 and a light source module 200. The light source module 200 includes a plurality of light sources 210. A structural part 140 corresponds to a light source 210. The light source module 200 may be an LED light bar, and the light source 210 may be an LED. The light of each light source 210 can correspond to one of the structural parts 140 on the light incident surface 130 after entering the light guide plate 100, and then passes through the light guide plate 100 through the light exit surface 110. The backlight module 20 can optionally be added with other optical films, such as reflective films, diffuser films, condensing films, etc., to improve optical properties. By the backlight module 20 including the aforementioned light guide plate 100, a backlight module 20 with a shorter light mixing area and a higher screen ratio can be provided. Please refer to the above for the details of the light guide plate 100, which will not be repeated here.

Please refer to FIG. 8, which is a three-dimensional schematic diagram of a display device 30 according to another embodiment of the present invention, and only a part of it is shown here. The display device 30 includes a backlight module 20 and a display panel 300, and the display panel 300 is disposed above the backlight module 20. The backlight module 20 is used to provide light for the display panel 300, and the display panel 300 may be an LCD panel. For details of the backlight module 20, please refer to the above, and will not be repeated here.

Please refer to Figure 9, which is a simulated light field distribution diagram of a conventional backlight module. Conventional backlight module The light guide plate is not provided with structural parts on the light incident surface, and the light exit surface is not provided with convex lenses, first microstructures, and second microstructures. The light guide plate is divided into 11 rows and 11 columns, that is, the light guide plate is divided into 121 areas, Measure the brightness of each area (the luminous flux emitted in each area) as shown in Table 1, and set the simulation condition Bo value (the distance from the side wall to the visible range) as 8.0mm. Among them, take Table 1 corresponding to the brightness of the area where the 5 points P1~P5 and 13 points P1~P13 are marked in the 9th figure, and calculate the uniformity of the 5 points P1~P5 and 13 points P1~P13 ( Uniformity) and Luminance Uniformity, as shown in formulas (II) and (III), where the minimum brightness (Lmin) is the minimum brightness in the taken area, and the maximum brightness (Lmax) is the brightness in the taken area For the largest one, the average brightness is the average brightness of the selected area: uniformity=(minimum brightness/maximum brightness)×100% (II); average brightness=average brightness (III).

Please refer to FIG. 10, which is a simulated light field distribution diagram of the backlight module 20 according to the present invention. Similarly, the light guide plate 100 is divided into 121 areas, the brightness of each area is measured as shown in Table 2, and the simulation condition Bo value is set to 3.5mm, and the average of 5 points such as P1~P5 and 13 points such as P1~P13 is calculated. The homogeneity and uniform brightness, the results of optical simulation analysis are shown in Table 2.

It can be seen from Table 1 and Table 2 that in order to obtain the simulation results, the Bo value must be set in advance to obtain the optical As for the simulation value, the Bo value of the conventional backlight module is set to a common width of 8.0mm, and the Bo value of the backlight module 20 of the present invention is set to 3.5mm; however, the number of divisions of the light guide plate is also 121 premises Next, the 5-point uniformity of the backlight module 20 of the present invention can be increased by about 8.14%, and the 13-point uniformity can be increased by about 15.49%. In addition, the 5-point average brightness or the 13-point average brightness can also be increased by about 16% and 20, respectively. %, it shows that the energy distribution area of the light-emitting surface 110 of the backlight module 20 of the present invention is larger and more uniform, and the Bo value hypothesis of the backlight module 20 of the present invention is correct and effective. The backlight module of the present invention The screen-to-body ratio of 20 is indeed higher than that of the conventional backlight module.

Compared with the prior art, the light guide plate of the present invention is provided with a convex lens, a plurality of first microstructures, and a plurality of second microstructures on the light emitting surface, which can increase the directivity and uniformity of the emitted light, and the stripe protrusion structure is advantageous It can prevent dark corners from appearing in the peripheral area, and can improve the uniformity of the light, and then can reduce the light mixing area, which is beneficial to increase the screen ratio. Preferably, the light guide plate of the present invention is provided with a structural part on the light incident surface, and the light from the light source is deflected and diverged by the structural part, which is conducive to the light entering the corners of the light guide plate and can increase the energy distribution area to further improve the light uniformity .

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made in accordance with the scope of the patent application of the present invention should fall within the scope of the present invention.

100: light guide plate

110: Glossy Surface

111: Central District

112: Peripheral area

121: Convex lens

122: The first microstructure

123: The second microstructure

130: Glossy surface

A: Part

B: Part

D1: first side length

D2: second side length

D3: The third side length

S: refracting surface

Claims (14)

A light guide plate, comprising: a light-emitting surface, comprising: a convex lens located at the center of the light-emitting surface; a plurality of first microstructures, the first microstructures being a ring structure, and the plurality of first microstructures are concentric with each other , And surround the periphery of the convex lens; and a plurality of second microstructures, the second microstructure is an arc-shaped structure, and surrounds the periphery of the plurality of first microstructures; wherein, the first microstructure Both the second microstructure and the second microstructure have a refraction surface for deflecting and transmitting a light, and at least the refraction surface of the second microstructure located at the outermost side is provided with a plurality of strip-shaped protrusion structures; and a light incident surface , Connected to the light-incident surface, the light-incident surface includes a plurality of structural parts formed with a plurality of light-incident microstructures, and the light-incident microstructures are used to diverge a light entering the light-incident surface. The light guide plate according to claim 1, wherein the degree of inclination of one of the plurality of refractive surfaces is different from the degree of inclination of the other of the plurality of refractive surfaces. The light guide plate according to claim 2, wherein the degree of inclination of the plurality of refractive surfaces gradually increases from the inside of the light emitting surface to the outside of the light emitting surface. The light guide plate according to claim 1, wherein the first microstructure and the second microstructure both have an arc edge, the strip-shaped protrusion structure is arc-shaped, and an extension of the strip-shaped protrusion structure The direction is substantially the same as an extension direction of the arc side. The light guide plate according to claim 1, wherein the light emitting mask has a central area and a peripheral area located at the periphery of the central area, and the refractive surface of the first microstructure and the second microstructure located in the peripheral area are provided There is the strip-shaped protrusion structure. The light guide plate according to claim 1, wherein the light-incident microstructure includes a refractive surface, and in the structure portion, one of the plurality of refractive surfaces has an inclination degree different from that of the plurality of refractive surfaces The degree of inclination of the other. The light guide plate according to claim 1, wherein the light incident microstructure includes a refractive surface, and in the structure portion, the inclination of the plurality of refractive surfaces gradually increases from the inside to the outside. The light guide plate according to claim 1, wherein the light incident microstructure is a ring structure or an arc structure, and the plurality of light incident microstructures are concentric with each other. The light guide plate according to claim 1, wherein the center of the plurality of light incident microstructures is a concave lens. The light guide plate according to claim 1, wherein the light incident surface corresponds to a light source module, the light source module includes a plurality of light sources, and one structure part corresponds to one light source. A backlight module includes the light guide plate according to any one of claims 1 to 10. A display device including: The backlight module according to claim 11; and a display panel arranged above the backlight module. A backlight module includes a light guide plate, the light guide plate includes: a light exit surface, including: a convex lens located at the center of the light exit surface; a plurality of first microstructures, the first microstructures being a ring structure, The plurality of first microstructures are concentric with each other and surround the periphery of the convex lens; and a plurality of second microstructures, the second microstructure is an arc-shaped structure, and surrounds the periphery of the plurality of first microstructures ; Wherein, the first microstructure and the second microstructure both have a refractive surface for deflecting a light, and at least the refractive surface of the second microstructure located on the outermost side is provided with a plurality of strips Shaped protrusion structure. A display device includes: a backlight module as described in claim 13; and a display panel arranged above the backlight module.

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