Light guide element and backlight module

Abstract

This invention provides a light guide element comprising a main body and an optical microstructure recessed into the bottom surface of the main body. The optical microstructure includes a light-facing surface and a backlight surface, respectively facing and away from the light-incident surface of the main body. The light-facing surface has a first section line on a first pseudo-plane perpendicular to the light-incident surface and parallel to the bottom surface, and a second section line on a second pseudo-plane parallel to the light-incident surface and perpendicular to the bottom surface. The first pseudo-arc line passes through a first vertex near the light-incident surface and multiple first endpoints away from the light-incident surface in the first section line. The second pseudo-arc line passes through a second vertex near the light-outcident surface and multiple second endpoints away from the light-outcident surface in the second section line. The radius of curvature R of the second pseudo-arc line is... xz The radius of curvature R greater than that of the first pseudo-arc xy The width W of the optical microstructure in the first direction parallel to the incident surface and the bottom surface. x The width W is greater than the width in the second direction, which is perpendicular to the incident light surface and the first direction and parallel to the bottom surface. y The light guide element and the backlight module having the light guide element of the present invention can improve the uniformity of light output.

Description

Technical Field

[0001] This invention relates to an optical element and an optical module, and more particularly to a light guide element and a backlight module. Background Technology

[0002] The backlight module includes a light source, a light guide element, a reflector, and an optical film assembly. Light emitted from the light source enters through the light-incident surface of the light guide element and is transmitted within it. Through a special design on the surface of the light guide element, the light can be directed outside the element. After passing through the prism sheets and diffusers of the optical film, the light directed outside the light guide element is converged and appropriately mixed to form a surface light source.

[0003] With the widespread adoption of backlight modules, improving their performance is an inevitable trend. There are many common ways to enhance the brightness of a module, such as using high-gain optical films or increasing the number of light-emitting elements. However, using high-gain optical films or increasing the number of light-emitting elements usually comes at the cost of increased price. Due to cost constraints, using high-gain optical films or increasing the number of light-emitting elements is less acceptable to the market. Therefore, a highly directional optical microstructure is used in the light guide element to improve the light emission efficiency of the backlight module. However, due to the characteristics of the highly directional optical microstructure, the light transmitted to the light-emitting surface of the light guide element has high directionality. If the astigmatism effect of the highly directional optical microstructure is poor, and the spacing between multiple light-emitting elements is large, uneven brightness can easily occur on the side of the light-emitting surface closer to the light-incident surface.

[0004] The "Background Art" paragraph is only used to help understand the content of this invention. Therefore, the content disclosed in the "Background Art" paragraph may include some prior art that is not known to those skilled in the art. The content disclosed in the "Background Art" paragraph does not mean that the content or the problem to be solved by one or more embodiments of this invention was known or recognized by those skilled in the art before this application was filed. Summary of the Invention

[0005] This invention provides a light guide element that can improve the uniformity of light output.

[0006] This invention provides a backlight module with excellent light emission uniformity.

[0007] Other objects and advantages of the present invention can be further understood from the technical features disclosed herein.

[0008] To achieve one or more of the above-mentioned objectives or other objectives, a light guide element according to an embodiment of the present invention includes a main body and an optical microstructure. The main body includes a bottom surface, opposing light-emitting surfaces disposed on the bottom surface, and a light-incident surface connecting the light-emitting surface and the bottom surface. The optical microstructure is recessed into the bottom surface of the main body. The optical microstructure includes a light-facing surface facing the light-incident surface and a backlight surface facing away from the light-incident surface. The light-facing surface is located between the backlight surface and the light-incident surface. A first pseudo-plane is perpendicular to the light-incident surface and parallel to the bottom surface. The light-facing surface has a first cross-section on the first pseudo-plane. The first cross-section has a first vertex near the light-incident surface and a plurality of first endpoints away from the light-incident surface and located on either side of the first vertex. A first pseudo-arc passes through the first vertex and the plurality of first endpoints. The first pseudo-arc has a radius of curvature R. xy and 15μm <R xy <60μm. The second pseudo-plane is parallel to the incident plane and perpendicular to the bottom plane. The facing plane has a second section on the second pseudo-plane. The second section has a second vertex near the emitting plane and multiple second endpoints on either side of the second vertex, away from the emitting plane. The second pseudo-arc passes through the second vertex and the multiple second endpoints. The second pseudo-arc has a radius of curvature R. xz And 30μm <R xz <120μm. The radius of curvature R of the second pseudo-arc. xz The radius of curvature R greater than that of the first pseudo-arc xy The optical microstructure has a first width W in a first direction parallel to the incident surface and the bottom surface. x The optical microstructure has a second width W in a second direction that is perpendicular to the incident light surface and the first direction, and parallel to the bottom surface. y First width W x Greater than the second width W y .

[0009] To achieve one or more of the above objectives or other objectives, a backlight module according to an embodiment of the present invention includes the above-mentioned light guide element and light source, wherein the light source is disposed next to the light incident surface of the main body of the above-mentioned light guide element.

[0010] Based on the above, since the light-facing surface of the optical microstructure of the light guide element is curved on a pseudo-plane perpendicular to the incident light surface, the light-facing surface of the optical microstructure can guide incident light at small angles to the exit light surface, as well as incident light at large angles. Therefore, when the spacing between the multiple light-emitting elements of the light source is large, the optical microstructure can not only improve the overall brightness of the backlight module, but also prevent the appearance of alternating bright and dark areas and / or oblique spraying on the side of the light-emitting surface closest to the light source, thereby improving the light emission uniformity and efficiency of the backlight module.

[0011] To make the above features and advantages of the present invention more apparent and understandable, specific embodiments are described below in conjunction with the accompanying drawings. Attached Figure Description

[0012] Figure 1 This is a cross-sectional schematic diagram of a backlight module according to an embodiment of the present invention.

[0013] Figure 2 This is a three-dimensional schematic diagram of an optical microstructure according to an embodiment of the present invention.

[0014] Figure 3 This is a top view schematic diagram of an optical microstructure according to an embodiment of the present invention.

[0015] Figure 4 This is a side view schematic diagram of an optical microstructure according to an embodiment of the present invention.

[0016] Figure 5 This is a front view schematic diagram of an optical microstructure according to an embodiment of the present invention.

[0017] Figure 6 This is a top view schematic diagram of an optical microstructure according to an embodiment of the present invention.

[0018] Figure 7 This is a top view schematic diagram of an optical microstructure according to an embodiment of the present invention.

[0019] Figure 8 This is a three-dimensional schematic diagram of the optical microstructure for comparison.

[0020] Figure 9 Show Figure 8 Comparative examples and Figure 2 The embodiment shows the luminance distribution on the side of the light-emitting surface closest to the light-receiving surface.

[0021] Figure 10 This is a three-dimensional schematic diagram of an optical microstructure according to another embodiment of the present invention.

[0022] Figure 11 This is a top view schematic diagram of an optical microstructure according to an embodiment of the present invention.

[0023] Figure 12 This is a side view schematic diagram of an optical microstructure according to an embodiment of the present invention.

[0024] Figure 13 This is a front view schematic diagram of an optical microstructure according to an embodiment of the present invention.

[0025] Figure 14 This is a top view schematic diagram of an optical microstructure according to another embodiment of the present invention.

[0026] Figure 15 This is a side view schematic diagram of an optical microstructure according to another embodiment of the present invention.

[0027] Figure 16 This is a front view schematic diagram of an optical microstructure according to another embodiment of the present invention.

[0028] Figure 17 This is a three-dimensional schematic diagram of an optical microstructure according to an embodiment of the present invention.

[0029] Figure 18 This is a three-dimensional schematic diagram of an optical microstructure according to another embodiment of the present invention.

[0030] Figure 19 This is a three-dimensional schematic diagram of an optical microstructure according to another embodiment of the present invention.

[0031] List of reference numerals

[0032] 10: Backlight Module

[0033] 100, 100': Light guide element

[0034] 110: Main Body

[0035] 112: Bottom surface

[0036] 114: Light-emitting surface

[0037] 116: Light-receiving surface

[0038] 120, 120', 120A, 120B, 120C, 120D, 120E: Optical microstructures

[0039] 122, 122', 122A, 122B, 122C, 122D, 122E: Sunlit side

[0040] 122a: Subplane

[0041] 122b, 122c: Side sub-arc surface

[0042] 122d, 122e: First sub-face

[0043] 122f, 122g: Second subface

[0044] 122h, 122i: Connecting subfaces

[0045] 124: Backlit side

[0046] 200: Light source

[0047] 210: Light-emitting element

[0048] 300: Reflective sheet

[0049] 400: Optical film assembly

[0050] 410: Lower diffusion sheet

[0051] 420: First Prism Slide

[0052] 430: Second Prism Slide

[0053] 440: Upper diffusion sheet

[0054] a, b, c, d: Semi-axis length

[0055] C1: First pseudo-arc

[0056] C2: Second pseudo-arc

[0057] D, S: Distance

[0058] E1: First quasi-elliptic curve

[0059] E2: Second quasi-elliptic curve

[0060] e1: First endpoint

[0061] e2: Second endpoint

[0062] H: Maximum depth

[0063] I1: First boundary

[0064] I2: Second boundary

[0065] K1: First segment

[0066] K2: Second segment

[0067] L1, L3: Edges

[0068] o1: Intersection

[0069] Q: Plane to be extended

[0070] R xy R xz radius of curvature

[0071] v1: First vertex

[0072] v2: Second vertex

[0073] W x First width

[0074] W y Second width

[0075] Xa: First major axis

[0076] Xb: First minor axis

[0077] Xc: Second axis

[0078] Xd: First axis

[0079] x: First direction

[0080] y: Second direction

[0081] z: Third-party direction

[0082] θ: Angle of attack. Detailed Implementation

[0083] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of a preferred embodiment with reference to the accompanying drawings. The directional terms mentioned in the following embodiments, such as up, down, left, right, front, or back, are merely for reference to the directions in the accompanying drawings. Therefore, the directional terms used are for illustrative purposes and not for limiting the present invention.

[0084] Reference will now be made in detail to exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same element references are used in the drawings and description to denote the same or similar parts.

[0085] For clarity, the figures in this specification depict a first perpendicular direction x, a second perpendicular direction y, and a third perpendicular direction z.

[0086] Figure 1 This is a cross-sectional schematic diagram of a backlight module according to an embodiment of the present invention. Please refer to... Figure 1 The backlight module 10 includes a light guide element 100 and a light source 200. The light guide element 100 includes a main body 110. The main body 110 includes a bottom surface 112, a light emitting surface 114 disposed opposite to the bottom surface 112, and a light incident surface 116 connecting the light emitting surface 114 and the bottom surface 112. The light source 200 is disposed beside the light incident surface 116 of the main body 110 of the light guide element 100. For example, in this embodiment, the light source 200 may selectively include a plurality of light-emitting diode elements 210 arranged and spaced apart from each other in a first direction x, but the present invention is not limited thereto.

[0087] In this embodiment, the backlight module 10 may further include a reflective sheet 300 disposed below the bottom surface 112 of the main body 110 of the light guide element 100. The backlight module 10 may further include an optical film assembly 400 disposed on the light-emitting surface 114 of the main body 110 of the light guide element 100. For example, in this embodiment, the optical film assembly 400 may include a lower diffuser 410, a first prism sheet 420, a second prism sheet 430, and an upper diffuser 440 sequentially stacked on the light-emitting surface 114, wherein the prism extension direction of the first prism sheet 420 and the prism extension direction of the second prism sheet 430 are staggered. However, the present invention is not limited thereto, and in other embodiments, the optical film assembly 400 may also include other types / numbers of optical films.

[0088] Figure 2 This is a three-dimensional schematic diagram of an optical microstructure according to an embodiment of the present invention. Figure 3 This is a top view schematic diagram of an optical microstructure according to an embodiment of the present invention. Figure 4 Side view schematic diagram of an optical microstructure according to an embodiment of the present invention. Figure 5 Front view schematic diagram of an optical microstructure according to an embodiment of the present invention.

[0089] It should be noted that for clear illustration and expression, Figures 2 to 5 the optical microstructure 120 is drawn to be complementary to Figure 1 the optical microstructure 120 of

[0090] Please refer to Figure 1 and Figure 2 . The light guide element 100 further includes an optical microstructure 120 that is recessed in the bottom surface 112 of the main body 110. The optical microstructure 120 includes a light-facing surface 122 and a light-backing surface 124. The light-facing surface 122 of the optical microstructure 120 faces the light-incident surface 116 of the main body 110. The light-backing surface 124 of the optical microstructure 120 faces away from the light-incident surface 116 of the main body 110. The light-facing surface 122 of the optical microstructure 120 is located between the light-backing surface 124 of the optical microstructure 120 and the light-incident surface 116 of the main body 110.

[0091] Please refer to Figure 4 . In this embodiment, the light-facing surface 122 of the optical microstructure 120 and the virtual extension plane Q of the bottom surface 112 of the main body 110 form a light-facing angle θ, and 2° < θ < 35°, but the present invention is not limited thereto. Please refer to Figure 1 and Figure 4 . In this embodiment, the optical microstructure 120 has a maximum depth H recessed in the bottom surface 112, and 2μm < H < 30μm, but the present invention is not limited thereto.

[0092] Please refer to Figure 1 and Figure 3 . The first virtual plane (for example: the xy plane where the first direction x and the second direction y are located) is perpendicular to the light-incident surface 116 of the main body 110 and parallel to the bottom surface 112 of the main body 110. The light-facing surface 122 of the optical microstructure 120 has a first intercept line K1 on the first virtual plane (for example: the xy plane). The first intercept line K1 has a first vertex v1 close to the light-incident surface 116 and multiple first end points e1 that are far from the light-incident surface 116 and are located on both sides of the first vertex v1 respectively. The first virtual arc C1 passes through the first vertex v1 and the multiple first end points e1. The first virtual arc C1 has a radius of curvature R xy . 15μm < R xy < 60μm.

[0093] Please refer to Figure 1 and Figure 5The second pseudo-plane (e.g., the xz plane containing the first direction x and the third direction z) is parallel to the incident surface 116 and perpendicular to the bottom surface 112. The facing surface 122 has a second section K2 on the second pseudo-plane (e.g., the xz plane). The second section K2 has a second vertex v2 near the emitting surface 114 and multiple second endpoints e2 located on either side of the second vertex v2 away from the emitting surface 114. The second pseudo-arc C2 passes through the second vertex v2 and the multiple second endpoints e2. The second pseudo-arc C2 has a radius of curvature R. xz 30μm <R xz <120μm.

[0094] Please refer to Figure 2 , Figure 3 and Figure 5 The radius of curvature R of the second pseudo-arc C2 xz The radius of curvature R is greater than that of the first pseudo-arc C1 xy Please refer to Figure 1 and Figure 2 In other words, the curvature of the light-facing surface 122 of the optical microstructure 120 on the pseudo-plane (e.g., the xy plane) perpendicular to the incident surface 116 is greater than the curvature on the pseudo-plane (e.g., the xz plane) parallel to the incident surface 116.

[0095] Please refer to Figure 1 , Figure 2 , Figure 4 and Figure 5 The optical microstructure 120 has a first width W in a first direction x parallel to the incident light surface 116 and the bottom surface 112. x The optical microstructure 120 has a second width W in a second direction y that is perpendicular to the light-incident surface 116 and the first direction x and parallel to the bottom surface 112. y And the first width W x Greater than the second width W y Please refer to Figure 2 and Figure 5 For example, in this embodiment, 10μm <W x <100μm, 10μm <W y <100μm, but the present invention is not limited thereto.

[0096] Please refer to Figure 1 and Figure 2It is worth mentioning that, because the light-facing surface 122 of the optical microstructure 120 is curved on a pseudo-plane (e.g., the xy plane) perpendicular to the incident light surface 116, the light-facing surface 122 of the optical microstructure 120 can guide incident light at small angles to the exit light surface 114, and also guide incident light at large angles to the exit light surface 114. Therefore, when the spacing between the multiple light-emitting elements 210 of the light source 200 is large, the optical microstructure 120 can not only improve the overall brightness of the backlight module 10, but also prevent the phenomenon of alternating bright and dark areas and / or oblique spraying on the side of the exit light surface 114 near the light source 200, thereby improving the light emission uniformity of the backlight module 10. Please refer to... Figure 1 , Figure 2 , Figure 3 and Figure 5 In particular, when Rxz>Rxy and Wx>Wy, the optical microstructure 120 improves the light emission uniformity and efficiency of the backlight module 10 on the side closer to the light incident surface 116.

[0097] Figure 6 This is a top view schematic diagram of an optical microstructure according to an embodiment of the present invention. Please refer to... Figure 1 and Figure 6 , Figure 6 The first boundary I1 between the light-facing surface 122 of the optical microstructure 120 and the bottom surface 112 of the main body 110 is marked. The first boundary I1 is a part of the first pseudo-elliptic curve E1. The first pseudo-elliptic curve E1 has a first major axis Xa in the second direction y. The first pseudo-elliptic curve E1 has a first minor axis Xb in the first direction x. The semi-axis length of the first major axis Xa is a, and the semi-axis length of the first minor axis Xb is b, and a is not equal to b.

[0098] Figure 7 This is a top view schematic diagram of an optical microstructure according to an embodiment of the present invention. Please refer to... Figure 1 and Figure 7 , Figure 7 The second boundary I2 between the backlight surface 124 of the optical microstructure 120 and the bottom surface 112 of the main body 110 is marked. The second boundary I2 is a part of the second pseudo-elliptic curve E2. The second pseudo-elliptic curve E2 has a first axis Xd and a second axis Xc in the first direction x and the second direction y, respectively. The semi-axis length of the first axis Xd of the second pseudo-elliptic curve E2 is d, and the semi-axis length of the second axis Xc of the second pseudo-elliptic curve E2 is c, and c is not equal to d.

[0099] Please refer to Figure 6 and Figure 7 In this embodiment, a > 1.5b and a > c. Therefore, on the side closer to the light-incident surface 116, the optical microstructure 120 can further improve the light emission uniformity and efficiency of the backlight module 10.

[0100] Please refer to Figure 1 and Figure 2 In this embodiment, the light-facing surface 122 of the optical microstructure 120 may include a sub-plane 122a and a plurality of side sub-arc surfaces 122b and 122c. The sub-plane 122a is inclined relative to the light-incident surface 116 and the bottom surface 112. The plurality of side sub-arc surfaces 122b and 122c are respectively connected to both sides of the sub-plane 122a, and each side sub-arc surface 122b and 122c is curved in the first direction x and the second direction y. However, the present invention is not limited thereto. In other embodiments, the light-facing surface 122 of the optical microstructure 120 may also have other forms, which will be illustrated in the following paragraphs.

[0101] Please refer to Figure 2 , Figure 3 and Figure 5 In this embodiment, the sub-plane 122a of the light-facing surface 122 intersects with multiple side sub-arc surfaces 122b and 122c at two edges L1, and the two edges L1 intersect with the backlight surface 124 at multiple intersection points o1. The multiple intersection points o1 have a distance S in the first direction x, and S < 2W. x / 3. That is to say, in this embodiment, the area ratio of the side sub-arc surfaces 122b and 122c to the entire light-facing surface 122 exceeds a certain size. As a result, on the side closer to the light-receiving surface 116, the optical microstructure 120 further enhances the light emission uniformity and visual quality of the backlight module 10.

[0102] Figure 8 This is a three-dimensional schematic diagram of the optical microstructure for comparison. Figure 8 Comparative example of optical microstructure 120' and Figure 2 The optical microstructure 120 in the embodiment is similar, except that: Figure 8 The optical microstructure 120' of the comparative example does not include the light-facing surface 122'. Figure 2 Multiple side sub-arc surfaces 122b, 122c of the embodiment.

[0103] Please refer to Figure 9 , Figure 9 Show Figure 8 Comparative examples and Figure 2 The embodiment exhibits a luminance distribution on the side of the light-emitting surface 114 closest to the light-incident surface 116. Compared to the comparative example, the light guide element 100 of this embodiment shows a more uniform luminance distribution on the side of the light-emitting surface 114 closest to the light-incident surface 116. Figure 9 The data demonstrates that the optical microstructure 120 of the embodiment can indeed improve the light emission uniformity and visual quality of the backlight module 10 on the side near the light-incident surface 116. Furthermore, when the brightness uniformity of the entire screen area is comparable, the light guide element 100 of this embodiment can provide an average luminance that is 5% higher than that of the comparative example within the screen area.

[0104] It must be noted that the following embodiments use the component reference numerals and some content from the foregoing embodiments, with the same reference numerals used to represent the same or similar components, and descriptions of the same technical content omitted. For explanations of the omitted parts, please refer to the foregoing embodiments; these will not be repeated in the following embodiments.

[0105] Figure 10 This is a three-dimensional schematic diagram of an optical microstructure according to another embodiment of the present invention. Figure 11 This is a top view schematic diagram of an optical microstructure according to an embodiment of the present invention. Figure 12 This is a side view schematic diagram of an optical microstructure according to an embodiment of the present invention. Figure 13 This is a front view schematic diagram of an optical microstructure according to an embodiment of the present invention.

[0106] Please refer to Figures 10 to 13 The optical microstructure 120A of this embodiment is similar to the aforementioned optical microstructure 120, except that the light-facing surface 122A of the optical microstructure 120A in this embodiment differs from the light-facing surface 122 of the aforementioned optical microstructure 120. Specifically, in this embodiment, the light-facing surface 122A is a continuous arc surface and does not have sub-planes. The optical microstructure 120A of this embodiment has similar effects to the aforementioned optical microstructure 120.

[0107] Figure 14 This is a top view schematic diagram of an optical microstructure according to another embodiment of the present invention. Figure 15 This is a side view schematic diagram of an optical microstructure according to another embodiment of the present invention. Figure 16 This is a front view schematic diagram of an optical microstructure according to another embodiment of the present invention.

[0108] Please refer to Figures 14 to 16 The optical microstructure 120B of this embodiment is similar to the optical microstructure 120 described above. The difference between the two is that the light-facing surface 122B of the optical microstructure 120B of this embodiment is different from the light-facing surface 122 of the optical microstructure 120 described above.

[0109] Specifically, in this embodiment, the light-facing surface 122B includes a plurality of first sub-surfaces 122d and 122e and a plurality of second sub-surfaces 122f and 122g, wherein the plurality of first sub-surfaces 122d and 122e are inclined relative to the light-incident surface 116 and the bottom surface 112 (see reference). Figure 1The plurality of first sub-surfaces 122d and 122e are connected to each other. The third pseudo-plane (e.g., the yz plane containing the second direction y and the third direction z) is perpendicular to the incident surface 116 and the bottom surface 112, and the plurality of first sub-surfaces 122d and 122e are tilted in opposite directions relative to the third pseudo-plane (e.g., the yz plane). The plurality of second sub-surfaces 122f and 122g are located on both sides of the plurality of first sub-surfaces 122d and 122e, respectively. The plurality of first sub-surfaces 122d and 122e intersect at the edge line L3, which is located on the third pseudo-plane (e.g., the yz plane). The plurality of second sub-surfaces 122f and 122g are tilted relative to the bottom surface 112, the incident surface 116 and the third pseudo-plane (e.g., the yz plane), and the plurality of second sub-surfaces 122f and 122g are tilted in opposite directions relative to the third pseudo-plane (e.g., the yz plane). In this embodiment, the multiple first sub-surfaces 122d and 122e are approximately planar, and the multiple second sub-surfaces 122f and 122g can be planar. Although the light-facing surface 122B in this embodiment includes multiple first sub-surfaces 122d and 122e and multiple second sub-surfaces 122f and 122g, it still conforms to the aforementioned characteristic that the first pseudo-arc passes through the vertex of the light-facing surface on the first pseudo-plane (xy plane) near the incident surface and multiple endpoints far from the incident surface and located on both sides of the vertex, and the first pseudo-arc has a radius of curvature R. xy and 15μm <R xy <60μm; it also conforms to the aforementioned characteristics of the second pseudo-arc line passing through the vertex near the incident surface and multiple endpoints far from the incident surface on the second pseudo-plane (xz plane) located on both sides of the vertex, and the second pseudo-arc line has a radius of curvature R. xz And 30μm <R xz <120μm. The optical microstructure 120B of this embodiment has similar effects to the aforementioned optical microstructure 120.

[0110] Figure 17 This is a three-dimensional schematic diagram of an optical microstructure according to an embodiment of the present invention. Please refer to... Figure 17The optical microstructure 120C of this embodiment is similar to the aforementioned optical microstructure 120B, except that the light-facing surface 122C of the optical microstructure 120C is different from that of the aforementioned optical microstructure 120B. Specifically, in this embodiment, the light-facing surface 122C further includes multiple connecting sub-surfaces 122h and 122i, which are connected between the first sub-surfaces 122d and 122e and the second sub-surfaces 122f and 122g, and are respectively located on both sides of a third pseudo-plane (e.g., the yz plane). In this embodiment, the multiple first sub-surfaces 122d and 122e, the multiple second sub-surfaces 122f and 122g, and the multiple connecting sub-surfaces 122h and 122i are multiple curved surfaces. The light-facing surface 122C of this embodiment also conforms to the aforementioned characteristics and curvature radius limitations of the first pseudo-arc and the second pseudo-arc, which respectively pass through the vertex of the light-facing surface on the first pseudo-plane (xy plane) and the second pseudo-plane (xz plane) near the light-incident surface and the multiple endpoints located on both sides of the vertex away from the light-incident surface. These will not be elaborated upon here. The optical microstructure 120C of this embodiment has similar effects to the aforementioned optical microstructure 120.

[0111] Figure 18 This is a three-dimensional schematic diagram of an optical microstructure according to another embodiment of the present invention. Please refer to... Figure 18 The optical microstructure 120D of this embodiment is similar to the aforementioned optical microstructure 120C, except that the light-facing surface 122D of the optical microstructure 120D in this embodiment is different from the light-facing surface 122C of the aforementioned optical microstructure 120C. Specifically, in this embodiment, the plurality of first sub-surfaces 122d and 122e are each a plurality of planes, the plurality of second sub-surfaces 122f and 122g are each a plurality of planes, and the plurality of connecting sub-surfaces 122h and 122i are each a plurality of curved surfaces. The light-facing surface 122D of this embodiment also conforms to the aforementioned characteristics and curvature radius limitation range of the first pseudo-arc and the second pseudo-arc, which respectively pass through the vertex of the light-facing surface on the first pseudo-plane (xy plane) and the second pseudo-plane (xz plane) near the light-incident surface and the plurality of endpoints located on both sides of the vertex, respectively. These will not be elaborated further here. The optical microstructure 120D of this embodiment has similar effects to the aforementioned optical microstructure 120.

[0112] Figure 19 This is a three-dimensional schematic diagram of an optical microstructure according to another embodiment of the present invention. Please refer to... Figure 19The optical microstructure 120E of this embodiment is similar to the aforementioned optical microstructure 120C, except that the light-facing surface 122E of the optical microstructure 120E is different from the light-facing surface 122C of the aforementioned optical microstructure 120C. Specifically, in this embodiment, multiple first sub-surfaces 122d and 122e are multiple planes, multiple second sub-surfaces 122f and 122g are multiple planes, and multiple connecting sub-surfaces 122h and 122i are multiple planes, and the inclination directions of the multiple connecting sub-surfaces 122h and 122i relative to the third pseudo-plane (e.g., the yz plane) are opposite. The light-facing surface 122E of this embodiment also conforms to the aforementioned characteristics and curvature radius limitation range of the first pseudo-arc and the second pseudo-arc, which respectively pass through the vertex of the light-receiving surface on the first pseudo-plane (xy plane) and the second pseudo-plane (xz plane) near the light-receiving surface and away from the light-receiving surface and located on both sides of the vertex, which will not be repeated here. The optical microstructure 120E of this embodiment has similar effects to the aforementioned optical microstructure 120.

[0113] In summary, a backlight module according to an embodiment of the present invention includes a light guide element and an optical microstructure. The optical microstructure is recessed into the bottom surface of the main body of the light guide element. The light-facing surface of the optical microstructure is curved on a pseudo-plane perpendicular to the light-incident surface. Therefore, the light-facing surface of the optical microstructure can guide incident light at small angles to the light-exit surface, and also guide incident light at large angles to the light-exit surface. Thus, when the spacing between the multiple light-emitting elements of the light source is large, the optical microstructure can not only improve the overall brightness of the backlight module, but also prevent the light-exit surface from exhibiting alternating bright and dark areas and / or oblique spraying patterns on the side closest to the light source, thereby improving the light emission uniformity and efficiency of the backlight module.

[0114] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. Any simple equivalent changes and modifications made in accordance with the claims and specification of the present invention are still within the scope of this patent. Furthermore, no embodiment or claim of the present invention needs to achieve all the objectives, advantages, or features disclosed in the present invention. In addition, the abstract and title of the invention are only used to assist in patent document retrieval and are not intended to limit the scope of the invention. Furthermore, the terms "first," "second," etc., mentioned in this specification or claims are only used to name elements or distinguish different embodiments or scopes, and are not used to limit the upper or lower limit of the number of elements.

Claims

1. A light guide element, characterized in that, The light guide element includes a main body and an optical microstructure, wherein The main body includes a bottom surface, a light-emitting surface, and a light-incident surface, wherein... The light-emitting surface is disposed opposite to the bottom surface; and The light-incident surface is connected between the light-outceasing surface and the bottom surface; and The optical microstructure is recessed into the bottom surface of the main body, wherein the optical microstructure includes a light-facing surface and a light-reflecting surface, wherein The light-facing surface faces the light-incident surface; as well as The backlight surface faces away from the light-incident surface, wherein the light-facing surface is located between the backlight surface and the light-incident surface; The first pseudo-plane is perpendicular to the incident surface and parallel to the bottom surface. The light-facing surface has a first section on the first pseudo-plane. The first section has a first vertex near the incident surface and multiple first endpoints located on either side of the first vertex away from the incident surface. A first pseudo-arc passes through the first vertex and the multiple first endpoints, and the first pseudo-arc has a radius of curvature R. xy And 15μm < R xy <60μm; The second pseudo-plane is parallel to the incident light surface and perpendicular to the bottom surface. The light-facing surface has a second section on the second pseudo-plane. The second section has a second vertex near the light-emitting surface and multiple second endpoints located on either side of the second vertex, away from the light-emitting surface. A second pseudo-arc passes through the second vertex and the multiple second endpoints, and the second pseudo-arc has a radius of curvature R. xz And 30μm < R xz <120μm; The radius of curvature R of the second pseudo-arc xz The radius of curvature R greater than that of the first pseudo-arc is xy ; The optical microstructure has a first width W in a first direction parallel to the light incident surface and the bottom surface. x The optical microstructure has a second width W in a second direction perpendicular to the light-incident surface and the first direction and parallel to the bottom surface. y And the first width W x Greater than the second width W y .

2. The light guide element according to claim 1, characterized in that, The light-facing surface and the bottom surface have a first boundary, which is part of a first pseudo-elliptic curve. The first pseudo-elliptic curve has a first major axis in the second direction and a first minor axis in the first direction.

3. The light guide element according to claim 2, characterized in that, The semi-axis length of the first major axis of the first pseudo-elliptic curve is a, the semi-axis length of the first minor axis of the first pseudo-elliptic curve is b, and a > 1.5b.

4. The light guide element according to claim 2, characterized in that, The backlight surface and the bottom surface have a second boundary, and the second boundary is part of a second pseudo-elliptic curve.

5. The light guide element according to claim 4, characterized in that, The first major axis of the first pseudo-elliptic curve has a semi-axis length of a, and the second pseudo-elliptic curve has a first axis and a second axis in the first direction and the second direction, respectively. The semi-axis length of the second axis of the second pseudo-elliptic curve is c, and a > c.

6. The light guide element according to claim 1, characterized in that, The light-facing surface includes a sub-plane and multiple side sub-arc surfaces, wherein The subplane is inclined relative to the incident light surface and the bottom surface; and The plurality of side sub-arc surfaces are respectively connected to both sides of the sub-plane, wherein each of the plurality of side sub-arc surfaces is curved in the first direction and the second direction.

7. The light guide element according to claim 6, characterized in that, The sub-plane and the plurality of side sub-arc surfaces intersect at two edges, and the plurality of edges intersect the backlight surface at multiple intersection points. The plurality of intersection points have a distance S in the first direction, and S < 2W. x / 3.

8. The light guide element according to claim 1, characterized in that, The sun-facing surface is a continuous arc surface.

9. The light guide element according to claim 1, characterized in that, The light-facing surface includes multiple first sub-surfaces and multiple second sub-surfaces, wherein The plurality of first sub-surfaces are inclined relative to the incident light surface and the bottom surface, wherein the plurality of first sub-surfaces are connected to each other, the third pseudo-plane is perpendicular to the incident light surface and the bottom surface, and the inclination directions of the plurality of first sub-surfaces relative to the third pseudo-plane are opposite; and The plurality of second sub-faces are located on both sides of the plurality of first sub-faces, wherein the plurality of first sub-faces intersect at an edge line located on the third pseudo-plane, and the plurality of second sub-faces are inclined relative to the bottom surface, the light-incident surface and the third pseudo-plane, and the inclination directions of the plurality of second sub-faces relative to the third pseudo-plane are opposite.

10. The light guide element according to claim 9, characterized in that, The light-facing surface also includes multiple connecting sub-surfaces. The plurality of connecting sub-faces are connected between the plurality of first sub-faces and the plurality of second sub-faces, and are respectively located on both sides of the third pseudo-plane.

11. The light guide element according to claim 10, characterized in that, The plurality of first sub-surfaces, the plurality of second sub-surfaces, and the plurality of connecting sub-surfaces are each a plurality of curved surfaces.

12. The light guide element according to claim 10, characterized in that, The plurality of first sub-surfaces are each a plane, the plurality of second sub-surfaces are each a plane, and the plurality of connecting sub-surfaces are each a curved surface.

13. The light guide element according to claim 10, characterized in that, The plurality of first sub-surfaces are each a plurality of planes, the plurality of second sub-surfaces are each a plurality of planes, the plurality of connecting sub-surfaces are each a plurality of planes, and the plurality of connecting sub-surfaces have opposite inclination directions relative to the third pseudo-plane.

14. The light guide element according to claim 1, characterized in that, The light-facing surface of the optical microstructure and the pseudo-extended plane of the bottom surface of the main body are interposed at a light-facing angle θ, where 2° < θ < 35°.

15. The light guide element according to claim 1, characterized in that, The optical microstructure has a maximum depth H recessed into the bottom surface, and 2μm < H < 30μm.

16. The light guide element according to claim 1, characterized in that, 10μm<W y <100μm.

17. A backlight module, characterized in that, The backlight module includes a light guide element and a light source, wherein The light guide element includes a main body and an optical microstructure, wherein The main body includes a bottom surface, a light-emitting surface, and a light-incident surface, wherein... The light-emitting surface is disposed opposite to the bottom surface; and The light-incident surface is connected between the light-outceasing surface and the bottom surface; and The optical microstructure is recessed into the bottom surface of the main body, wherein the optical microstructure includes a light-facing surface and a light-reflecting surface, wherein The light-facing surface faces the light-incident surface; as well as The backlight surface faces away from the light-incident surface, wherein the light-facing surface is located between the backlight surface and the light-incident surface; The first pseudo-plane is perpendicular to the incident surface and parallel to the bottom surface. The light-facing surface has a first section on the first pseudo-plane. The first section has a first vertex near the incident surface and multiple first endpoints located on either side of the first vertex away from the incident surface. A first pseudo-arc passes through the first vertex and the multiple first endpoints, and the first pseudo-arc has a radius of curvature R. xy And 15μm < R xy <60μm; The second pseudo-plane is parallel to the incident light surface and perpendicular to the bottom surface. The light-facing surface has a second section on the second pseudo-plane. The second section has a second vertex near the light-emitting surface and multiple second endpoints located on either side of the second vertex, away from the light-emitting surface. A second pseudo-arc passes through the second vertex and the multiple second endpoints, and the second pseudo-arc has a radius of curvature R. xz And 30μm < R xz <120μm; The radius of curvature R of the second pseudo-arc xz The radius of curvature R greater than that of the first pseudo-arc is xy ; The optical microstructure has a first width W in a first direction parallel to the light incident surface and the bottom surface. x The optical microstructure has a second width W in a second direction perpendicular to the light-incident surface and parallel to the bottom surface. y And the first width W x Greater than the second width W y ;as well as The light source is positioned next to the light-incident surface.

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