Light guide plate, backlight module and display device

Abstract

The present invention relates to a light guide plate, a backlight module and a display device. The light guide plate comprises a light emitting surface, and the light emitting surface comprises 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 an annular structure, the plurality of first microstructures are concentric with each other and surround the periphery of the convex lens, and 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 the transmitted light, and at least a plurality of strip-shaped protrusion structures are provided on the refractive surface of the outermost second microstructure.

Description

Technical Field

[0001] The invention relates to a light guide plate, a backlight module and a display device, and in particular to a light guide plate with good optical quality, and a backlight module and a display device using the light guide plate. Background Art

[0002] Light Emitting Diode (LED) has become the mainstream backlight source of Liquid Crystal Display (LCD) due to its advantages such as small size, environmental protection and long life. Since LED has the luminous characteristics of a point light source, it has the problem of uneven luminous intensity.

[0003] Please refer to Figure 1 , which is a schematic diagram of the appearance of a light guide plate 10 of a conventional LCD. The light guide plate 10 includes a light emitting surface 11, and the light emitting surface 11 can be divided into an active area (AA) 11a and a mixing area (Mixing area) 11b according to functional characteristics. The frame 13 includes a lower frame 13a. The LED (not shown) is arranged on one side of the light guide plate 10. The light emitted by the LED enters the mixing area 11b of the light guide plate 10 so that the light is homogenized and then emitted from the active area 11a. The active area 11a corresponds to the visible range of the conventional LCD. In order to make the active area 11a meet the requirement of uniform brightness, it is usually necessary to configure a sufficient mixing distance C1. The longer the mixing distance C1, the lower the ratio of the active area 11a to the light emitting surface 11, that is, the lower the screen ratio of the LCD. Generally, the sum of the mixed light distance C1 and the length C2 of the lower frame 13a is called the Bo (Border) value (i.e., Bo=C1+C2, defined as the distance from the side wall to the visible range), and the Bo value is used as an indicator of the screen ratio. The lower the Bo value, the higher the screen ratio of the LCD.

[0004] In order to meet the current market demand, how to develop LCDs with high screen-to-body ratio and uniform light output has become the goal of relevant industry players. Summary of the invention

[0005] The object of the present invention is to provide a light guide plate, a backlight module and a display device to solve the above problems.

[0006] According to one embodiment of the present invention, a light guide plate is provided, comprising a light emitting surface. The light emitting surface comprises 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 an annular structure, and the 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 the transmitted light, and at least a plurality of strip-shaped protrusion structures are provided on the refractive surface of the outermost second microstructure.

[0007] According to another embodiment of the present invention, a backlight module is provided, comprising the aforementioned light guide plate.

[0008] According to another embodiment of the present invention, a display device is provided, comprising the aforementioned backlight module and a display panel, wherein the display panel is disposed above the backlight module.

[0009] 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 directionality and uniformity of the emitted light. Combined with the strip-shaped protrusion structure, it can help prevent the occurrence of dark corners in the peripheral area, thereby improving the uniformity of the light emission and obtaining a backlight module or display device with a small mixed light area and a high screen ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 The figure is a schematic diagram of the appearance of a light guide plate of a conventional liquid crystal display.

[0011] Figure 2 is a top view of a light guide plate according to an embodiment of the present invention.

[0012] Figure 3 yes Figure 2 A partial enlarged view of part A in FIG.

[0013] Figure 4 yes Figure 2 Schematic diagram of part A in FIG.

[0014] Figure 5 yes Figure 2 A cross-sectional view of portion B along section line 4-4.

[0015] Figure 6 yes Figure 4 A schematic cross-sectional view of the structural part in FIG.

[0016] Figure 7 It is a three-dimensional schematic diagram of a backlight module according to another embodiment of the present invention.

[0017] Figure 8 is a schematic three-dimensional diagram of a display device according to yet another embodiment of the present invention.

[0018] Fig. 9 It is a light field simulation distribution diagram of a conventional backlight module in a comparative implementation manner.

[0019] Fig.10 It is a light field simulation distribution diagram of a backlight module according to another embodiment of the present invention. DETAILED DESCRIPTION

[0020] The above and other technical contents, features and effects of the present invention will be clearly presented in the detailed description of the preferred embodiments with reference to the accompanying drawings. The directional terms mentioned in the following embodiments, such as up, down, left, right, front, back, bottom, top, etc., are only the directions with reference to the accompanying drawings. Therefore, the directional terms used herein are only used to illustrate and not to limit the present invention. In addition, in the following embodiments, the same or similar elements will be marked with the same or similar reference numerals.

[0021] In the present invention, the light guide plate can be used in a backlight module, and the backlight module can be used to provide a light source for a liquid crystal display (LCD) panel. Each component in the backlight module includes a bottom surface and a top surface, and the bottom surface and the top surface are defined with the LCD panel as a reference. The side of each component away from the LCD panel is the bottom surface, and the side facing the LCD panel is the top surface. The center referred to in the present invention refers to the relative center based on the overall component, not the absolute position.

[0022] Please refer to Figure 2 and Figure 5 , Figure 2 is a top view of a light guide plate 100 according to an embodiment of the present invention, Figure 5 yes Figure 2 The cross-sectional view of section B along section line 4-4 is shown in Figure 5In order to avoid the interference between the section line and the light L, the section line 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 can also be located at the center relative to the active area (AA) and the visual area (VA) of the display device used. The first microstructure 122 is an annular structure, and the 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, and surrounds the periphery of the convex lens 121 and / or the first microstructure 122. On the light emitting surface 110 of the light guide plate 100 of this embodiment, a convex lens 121, a first microstructure 122 surrounding the periphery of the convex lens 121, and a second microstructure 123 surrounding the periphery of the plurality of first microstructures 122 are sequentially arranged from the center to the periphery, and these structures form a concentric microstructure pattern. Each first microstructure 122 and each second microstructure 123 has a refractive surface S for deflecting the transmitted light L (see Figure 5 ). Please also refer to Figure 3 and Figure 4 , Figure 3 yes Figure 2 A partial enlarged view of part A in Figure 4 yes Figure 2 A three-dimensional schematic diagram of part A in FIG. Figure 3 and Figure 4 As shown, at least a plurality of strip-shaped protrusion structures 124 are provided on the refractive surface S of the outermost second microstructure 123. In addition, for the sake of simplicity, Figure 2 The strip protrusion structure 124 is omitted in the figure, and the strip protrusion structure 124 is only shown in FIG. Figure 3 and Figure 4 middle.

[0023] Please refer to Figure 5 , which shows a convex lens 121 and three first microstructures 122 adjacent to the convex lens 121, which are first microstructures 122a, 122b, and 122c from the inside to the outside, and the refractive surfaces S of the three first microstructures 122a, 122b, and 122c are refractive surfaces S1, S2, and S3 in sequence. The inclinations of the multiple refractive surfaces S1, S2, and S3 are different from each other, and the inclinations of the multiple refractive surfaces S1, S2, and S3 gradually increase from the inside of the light-emitting surface 110 to the outside of the light-emitting surface 110. Figure 5The description is made by taking the portion B of the light guide plate 100 as an example, but 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, the inclination degree of one of the multiple refractive surfaces S may be different from the inclination degree of another of the multiple refractive surfaces S. Preferably, the inclination degrees of the multiple refractive surfaces S gradually change from the inside of the light emitting surface 110 to the outside of the light emitting surface 110. For example, the inclination degrees of the multiple refractive surfaces S may gradually increase from the inside of the light emitting surface 110 to the outside of the light emitting surface 110. In the present embodiment, the refractive surfaces S (S1, S2, S3) are planes, however, the present invention is not limited thereto, and in other embodiments, the refractive surfaces S (S1, S2, S3) may also be curved surfaces, for example, similar to the convex lens 121, being curved surfaces convex outward.

[0024] 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 as a whole can be regarded as a convex lens, which is hereinafter referred to as an integral convex lens to distinguish it from the convex lens 121. According to the mirror making formula, as shown in formula (I):

[0025]

[0026] In formula (I), f is the focal length of the lens, n is the refractive index of the lens material, and n m is the refractive index of the material surrounding the lens, R1 is the curvature radius of the side surface of the lens close to the light source, and R2 is the curvature radius of the side surface of the lens away from the light source. Formula (I) is applied to the integral convex lens, and the integral convex lens faces the bottom surface 150 of the light guide plate 100 (see Figure 4 ) is R1, and the curvature radius of the side of the integral convex lens facing outward is R2. By adjusting the values ​​of R1 and R2, the light L emitted from the light emitting surface 110 can be parallel light. For example, when R1=R2≒0.3mm and f is infinite, the integral convex lens is a parallel light lens, which is beneficial to the directionality and uniformity of the emitted light.

[0027] In detail, Figures 2 to 4 As shown, 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 the extending direction E2 of each of the strip-shaped protrusion structures 124 is substantially the same as the extending direction E1 of the arc edge E.

[0028] like Figures 2 to 4As shown, the light emitting surface 110 may have a central area 111 and a peripheral area 112 located outside the central area 111, and the refractive surface S of the second microstructure 123 in the peripheral area 112 is provided with a strip-shaped protrusion structure 124. For example, the peripheral area 112 may be a side adjacent to the light guide plate 100 where no light source is provided. In the present embodiment, the range covered by the central area 111 is relatively wide, and the peripheral area 112 only includes the second microstructure 123. However, the present invention is not limited thereto. In other embodiments, the range covered by the central area 111 may be narrowed, and the peripheral area 112 may include both the first microstructure 122 and the second microstructure 123. In this case, the refractive surfaces S of the first microstructure 122 and the second microstructure 123 in the peripheral area 112 are provided with a strip-shaped protrusion structure 124. In addition, when a portion of the same first microstructure 122 or the same second microstructure 123 falls on the central area 111 and the remaining portion falls on the peripheral area 112, a protrusion structure 124 may be provided on the refractive surface S of the remaining portion that only falls on the peripheral area 112, such as Figure 3 The strip-shaped protrusion structure 124 can diverge the light L, so by providing the strip-shaped protrusion structure 124 in the peripheral area 112 , it is helpful to prevent dark corners from appearing in the peripheral area 112 , and further improve the light uniformity of the light guide plate 100 .

[0029] Please refer to Figure 2 , the peripheral area 112 has a first side length D1 and a second side length D2, and the central area 111 has a third side length D3. As for the side length of one side of the light guide plate 100, the side length of the side is the sum of the first side length D1, the second side length D2 and the third side length D3, wherein the sum of the first side length D1 and the second side length D2 accounts for a ratio greater than 0% and less than or equal to 10% of the side length (D1+D2+D3). Thus, on the one hand, dark corners can be prevented from appearing in the peripheral area 112, and on the other hand, the collimation of the light L emitted from the light emitting surface 110 can be maintained, thereby improving the front brightness.

[0030] like Figure 4 As shown, the light guide plate 100 may further include a light incident surface 130, and the light incident surface 130 is connected to the light emitting surface 110. The light incident surface 130 includes a plurality of structural parts 140. 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, for dispersing the light entering the light incident surface 130. Please also refer to Figure 6 , which is Figure 4Schematic cross-sectional view of the structural portion 140 in FIG. For the sake of simplicity, the section lines are omitted. In detail, the structural portion 140 includes a first light incident microstructure 141 located in 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 a concave lens, and the second light incident microstructure 142 may be a ring structure or an arc structure. Here, the arc structure is taken as an example, and the plurality of second light incident microstructures 142 are concentric with each other.

[0031] Each second light incident microstructure 142 includes a refractive surface T. For the sake of clarity, Figure 6 The three second light-incident microstructures 142 adjacent to the first light-incident microstructure 141 are marked separately, and are second light-incident microstructures 142a, 142b, and 142c from the inside to the outside. The refractive surfaces T of the second light-incident microstructures 142a, 142b, and 142c are refractive surfaces T1, T2, and T3 in sequence. The inclinations of the multiple refractive surfaces T1, T2, and T3 are different from each other, and the inclinations of the multiple refractive surfaces T1, T2, and T3 gradually increase from the inside of the structure portion 140 to the outside of the structure portion 140. As for the structure portion 140 as a whole, in the multiple second light-incident microstructures 142, the inclination of one of the multiple refractive surfaces T may be different from the inclination of another of the multiple refractive surfaces T. Preferably, the inclinations of the multiple refractive surfaces T gradually change from the inside of the structure portion 140 to the outside of the structure portion 140, for example, the inclinations of the multiple refractive surfaces T may gradually increase from the inside of the structure portion 140 to the outside of the structure portion 140. In this embodiment, the refractive surface T (T1, T2, T3) is a curved surface, and is similar to the first light incident microstructure 141, a curved surface concave inwardly. However, the present invention is not limited thereto, and in other embodiments, the refractive surface T (T1, T2, T3) may also be a plane.

[0032] 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 structure portion 140 formed by the combination of the first light-incident microstructure 141 and the plurality of second light-incident microstructures 142 can be regarded as a concave lens as a whole. Applying the above formula (I) to the structure portion 140, the radius of curvature of the outer side 143 of the structure portion 140 is R1, and the radius of curvature of the inner side 144 of the structure portion 140 is R2. By adjusting the values ​​of R1 and R2, the light entering the structure portion 140 from the outer side 143 and passing through the inner side 144 can be made to be divergent light. For example, when R1 = infinity, R2 = 0.5 mm, and f is a negative value, the structure portion 140 is a divergent light lens, which can facilitate the light to enter each corner inside the light guide plate 100 and increase the energy distribution area, thereby further improving the uniformity of light output.

[0033] Please refer to Figure 7, which is a three-dimensional schematic diagram of a backlight module 20 according to another embodiment of the present invention, only a part of which 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, and the structural part 140 is arranged corresponding to the light source 210, wherein the light source module 200 can be an LED light bar, and the light source 210 can be an LED. After the light of each light source 210 enters the light guide plate 100 corresponding to one of the structural parts 140 on the light incident surface 130, it passes through the light guide plate 100 from the light exiting surface 110. The backlight module 20 can selectively be provided with other optical films, such as a reflective film, a diffuser, a prism film (condenser film), etc., to enhance the optical properties. By making the backlight module 20 include the aforementioned light guide plate 100, the backlight module 20 can have a shorter light mixing area and a higher screen ratio. Please refer to the above for details about the light guide plate 100, which will not be repeated here.

[0034] Please refer to Figure 8 , which is a three-dimensional schematic diagram of a display device 30 according to another embodiment of the present invention, only a part of which is shown here. The display device 30 includes a backlight module 20 and a display panel 300, and the display panel 300 is arranged above the backlight module 20. The backlight module 20 is used to provide light to the display panel 300, and the display panel 300 can be an LCD panel. For details about the backlight module 20, please refer to the above, which will not be repeated here.

[0035] Please refer to Fig. 9 , which is a light field simulation distribution diagram of a conventional backlight module. The light incident surface of the light guide plate of the conventional backlight module is not provided with a structural part, and the light exit surface is not provided with a convex lens, a first microstructure and a second microstructure. The light guide plate is divided into 11 rows and 11 columns, that is, the light guide plate is divided into 121 areas. The measured brightness of each area (the luminous flux emitted in each area) is shown in Table 1, wherein the simulation condition Bo value (the distance from the side wall to the visible range) is set to 8.0 mm. Among them, the corresponding value in Table 1 is taken Fig. 9 The brightness of the area where the 5 points P1 to P5 and the 13 points P1 to P13 are located is calculated, and the uniformity (Uniformity) and luminance (Luminance Uniformity) of the 5 points P1 to P5 and the 13 points P1 to P13 are calculated, as shown in formulas (II) and (III), where the minimum brightness (Lmin) is the minimum brightness in the area, the maximum brightness (Lmax) is the maximum brightness in the area, and the average brightness is the average brightness of the area:

[0036] Uniformity = (minimum brightness / maximum brightness) × 100% (II);

[0037] Average luminance = average brightness value (III).

[0038] Please refer to Fig.10 , which is a light field simulation distribution diagram of the backlight module 20 according to the present invention. Similarly, the light guide plate 100 is divided into 121 areas, and the brightness of each area is measured as shown in Table 2, where the simulation condition Bo value is set to 3.5mm. The uniformity and average brightness of 5 points such as P1 to P5 and 13 points such as P1 to P13 are calculated, and the optical simulation analysis results are shown in Table 2.

[0039]

[0040]

[0041]

[0042] It can be seen from Table 1 and Table 2 that in order to obtain the simulation results, the Bo value needs to be set in advance to obtain the optical simulation value, so the Bo value of the conventional backlight module is set to the common width of 8.0 mm, and the Bo value of the backlight module 20 of the present invention is set to 3.5 mm. However, under the premise that the number of area divisions of the light guide plate is also 121, the 5-point uniformity of the backlight module 20 of the present invention can be improved by about 8.14%, and the 13-point uniformity can be improved by about 15.49%. In addition, the 5-point average brightness or the 13-point average brightness is also improved by about 16% and 20%, respectively, which proves that the energy distribution area of ​​the light-emitting surface 110 of the backlight module 20 according to the present invention is larger and more uniform, thereby confirming that the assumption of the Bo value of the backlight module 20 of the present invention is correct and effective. Therefore, the screen ratio of the backlight module 20 of the present invention is indeed improved compared with the conventional backlight module.

[0043] 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 directionality and uniformity of the emitted light, and combined with the strip-shaped protrusion structure, it can help prevent the occurrence of dark corners in the peripheral area, thereby improving the uniformity of the light emission, and further reducing the mixed light area, which is beneficial to improve 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 of the light source is deflected and diverged by the structural part, which can help the light enter every corner inside the light guide plate, thereby increasing the energy distribution area to further improve the uniformity of the light emission.

[0044] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

[0045] [List of Reference Numerals]

[0046] 10, 100 Light guide plate

[0047] 20 Backlight module

[0048] 30 Display device

[0049] 11 light emitting surface

[0050] 11a Validity Zone

[0051] 11b Mixed light area

[0052] 13. Border

[0053] 13a Bottom border

[0054] 110 Light emitting surface

[0055] 111 Central District

[0056] 112 Surrounding Area

[0057] 121 Convex lens

[0058] 122, 122a, 122b, 122c first microstructure

[0059] 123 Second Microstructure

[0060] 124 Strip-like protrusion structure

[0061] 130 Light incident surface

[0062] 140 Structure

[0063] 141 First Light Entrance Microstructure

[0064] 142, 142a, 142b, 142c second light incident microstructure

[0065] 143 Outside

[0066] 144 Inside

[0067] 150 Bottom

[0068] 200 Light source module

[0069] 210 Light Source

[0070] 300 Display Panel

[0071] Part A, B

[0072] Bo is the sum of the mixed light distance and the length of the lower frame

[0073] C1 Mixed Light Distance

[0074] C2 Length

[0075] D1 First side length

[0076] D2 Second side length

[0077] D3 Length of the third side

[0078] E Arc Edge

[0079] E1, E2 extension direction

[0080] L Ray

[0081] P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13 points

[0082] S, S1, S2, S3 refractive surface

[0083] T, T1, T2, T3 refractive surfaces.

Claims

1. A light guide plate, characterized in that: Include: The light emitting surface includes: A convex lens located at the center of the light emitting surface; A plurality of first microstructures, each of which is a ring-shaped structure, and the plurality of first microstructures are concentric with each other and surround the periphery of the convex lens; as well as A plurality of second microstructures, wherein the second microstructures are arc-shaped structures and surround the peripheries of the plurality of first microstructures; Wherein, both the first microstructure and the second microstructure have a refractive surface for deflecting the transmitted light, and at least the refractive surface of the second microstructure located at the outermost side is provided with a plurality of strip-shaped protrusion structures, The light emitting surface has a central area and a peripheral area located outside the central area, and the strip-shaped protrusion structure is provided on the refractive surfaces of the first microstructure and the second microstructure located in the peripheral area, and Wherein, both the first microstructure and the second microstructure have arc edges, the strip-shaped protrusion structure is arc-shaped, and the extension direction of the strip-shaped protrusion structure is the same as the extension direction of the arc edge.

2. The light guide plate according to claim 1, characterized in that: The inclination degree of one of the plurality of refractive surfaces is different from the inclination degree of another of the plurality of refractive surfaces.

3. The light guide plate according to claim 2, characterized in that: The inclination degrees of the multiple refractive surfaces gradually increase from the inside of the light emitting surface to the outside of the light emitting surface.

4. The light guide plate according to claim 1, characterized in that: Also includes: The light incident surface is connected to the light emitting surface, and the light incident surface includes a plurality of structural parts, and the structural parts are formed with a plurality of light incident microstructures, and the light incident microstructures are used to diffuse the light entering the light incident surface.

5. The light guide plate according to claim 4, characterized in that: The light incident microstructure includes a refractive surface. In the structural portion, the inclination degree of one of the refractive surfaces is different from the inclination degree of another of the refractive surfaces.

6. The light guide plate according to claim 4, characterized in that: The light incident microstructure includes a refractive surface. In the structure portion, the inclination degrees of the multiple refractive surfaces gradually increase from the inside of the structure portion to the outside of the structure portion.

7. The light guide plate according to claim 4, characterized in that: The light incident microstructure is a ring-shaped structure or an arc-shaped structure, and a plurality of the light incident microstructures are concentric with each other.

8. The light guide plate according to claim 4, characterized in that: The light incident microstructure located at the center of the structure portion among the plurality of light incident microstructures is a concave lens.

9. The light guide plate according to claim 4, characterized in that: The light incident surface is arranged corresponding to a light source module, the light source module includes a plurality of light sources, and the structural part is arranged corresponding to the light source.

10. A backlight module, characterized in that: The invention comprises the light guide plate according to any one of claims 1 to 9.

11. A display device, characterized in that: Include: The backlight module according to claim 10; and The display panel is arranged above the backlight module.

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