Backlight module having light guide microstructure with sparse and dense distribution characteristics, and display

Abstract

A backlight module having a light guide microstructure with sparse and dense distribution characteristics. The backlight module comprises a light source and a light guide plate. The light guide plate is used for being coupled with the light source. The light guide plate comprises a light incident surface, a light exit surface and a bottom surface that are adjacent to the light incident surface, and a plurality of strip-shaped microstructures and a plurality of light guide microstructures arranged on the bottom surface. Light emitted by the light source enters the light guide plate from the light incident surface, and two opposite sides of the light incident surface are respectively aligned with two opposite sides of the light source. The bottom surface is provided with two peripheral blocks arranged in a first direction, and a central block located between the peripheral blocks. Each strip-shaped microstructure extends in a second direction intersecting the first direction. Each light guide microstructure is located between any adjacent two strip-shaped microstructures, and the light guide microstructure extends in the first direction. The unit area proportion of the light guide microstructure in the central block is greater than the unit area proportion of the light guide microstructure in the peripheral blocks.

Description

Backlight module and display with light-guiding microstructure having sparse and dense distribution characteristics Technical Field

[0001] The present invention relates to a light emitting module, in particular to a backlight module and a display using the backlight module. Background Art

[0002] The light guide plate has a light incident surface, a light emitting surface, a reflective surface and two side edges, wherein the light incident surface, the light emitting surface and the reflective surface are all located between the two side edges. The light provided by the light source enters the light guide plate from the light incident surface of the light guide plate and is emitted from the light emitting surface of the light guide plate. In order to allow the light passing through the interior of the light guide plate to be mixed more evenly, microstructures such as dot-shaped or strip-shaped are provided on the light emitting surface or reflective surface of the light guide plate. Generally speaking, after light enters the light guide plate from the light incident surface, it travels in a direction away from the light incident surface, and the light will attenuate in the process of traveling. When the attenuation degree of the areas adjacent to the two side edges of the light guide plate is greater than the attenuation degree of the central area of ​​the light guide plate, it will cause the light guide plate to have a dark shadow in the light emitting corner away from the light incident surface.

[0003] Summary of the Invention

[0004] Therefore, the present invention provides a backlight module having a light guide microstructure with a sparse and dense distribution characteristic. This backlight module can improve the shadow problem in the light emitting corners of the light guide plate, thereby meeting the demand for improving light emitting uniformity.

[0005] The present invention also provides a display using a backlight module having a sparse-dense distribution characteristic of the light-guiding microstructure.

[0006] At least one embodiment of the present invention provides a backlight module with a light-guiding microstructure having a sparse-dense distribution characteristic, comprising a light source and a light guide plate, the light guide plate being used to couple with the light source and comprising a light incident surface, a light exit surface adjacent to the light incident surface, and a bottom surface. The light source is adjacent to the light incident surface, and the light emitted by the light source enters the light guide plate from the light incident surface, and the two opposite sides of the light incident surface are respectively aligned with the two opposite sides of the light source. The bottom surface is arranged opposite to the light exit surface, and the light incident surface is connected between the light exit surface and the bottom surface. The bottom surface has a central block and two peripheral blocks, and the central block is located between the two peripheral blocks, and the central block and the peripheral blocks are arranged along a first direction. The light guide plate further comprises a plurality of strip microstructures and light-guiding microstructures arranged on the bottom surface, the strip microstructures are distributed in the central block and the peripheral blocks, and each strip microstructure extends along a second direction, and the first direction intersects with the second direction. At least one light-guiding microstructure is located between any two adjacent strip-shaped microstructures, and each light-guiding microstructure extends along the first direction. The unit area ratio of the light-guiding microstructures in the central block is greater than the unit area ratio of the light-guiding microstructures in the peripheral blocks.

[0007] In one embodiment of the present invention, there is a distance between two adjacent strip-shaped microstructures, and each distance in the central block is greater than any distance in the peripheral blocks.

[0008] In one embodiment of the present invention, each of the strip-shaped microstructures has a width, and the widths of the strip-shaped microstructures are the same.

[0009] In one embodiment of the present invention, the spacing decreases gradually from the central block toward the peripheral blocks.

[0010] In one embodiment of the present invention, the unit area ratio of the light-guiding microstructures in the first direction conforms to a normal distribution.

[0011] In one embodiment of the present invention, the light incident surface is perpendicular to the second direction, and the second direction is perpendicular to the first direction.

[0012] In one embodiment of the present invention, each of the strip-shaped microstructures and the light-guiding microstructures has a surface, and the surface protrudes from the bottom surface of the light guide plate.

[0013] In one embodiment of the present invention, each of the strip-shaped microstructures and the light-guiding microstructures has a surface, and the surface is recessed into the bottom surface of the light guide plate.

[0014] In one embodiment of the present invention, each of the strip-shaped microstructures has a curvature radius, and the curvature radius of the strip-shaped microstructures located in the central block is smaller than the curvature radius of the strip-shaped microstructures located in the peripheral block.

[0015] In one embodiment of the present invention, each of the strip-shaped microstructures has a width, and the width of the strip-shaped microstructures located in the central block is smaller than the width of the strip-shaped microstructures located in the peripheral block.

[0016] In one embodiment of the present invention, each of the light-guiding microstructures includes at least two asymmetric reflective planes.

[0017] In one embodiment of the present invention, there is a distance between two adjacent light-guiding microstructures, and the distance decreases along a direction away from the light incident surface.

[0018] In one embodiment of the present invention, the distribution of the dot microstructures along the second direction is from dense to sparse.

[0019] In one embodiment of the present invention, the light guide plate further includes a plurality of lattice microstructures, which are disposed on the bottom surface and distributed in the front third of the area from the light incident surface.

[0020] At least one embodiment of the present invention provides a display comprising a backlight module having the aforementioned light-guiding microstructure with sparse-dense distribution characteristics and a display panel, wherein the display panel is disposed relative to the backlight module.

[0021] Based on the above, the present invention achieves control over the light output of the light guide plate by intersecting strip microstructures and light-guiding microstructures on the bottom surface of the light guide plate. By varying the configuration and shape of the strip microstructures and light-guiding microstructures, the unit area ratio of the light guide microstructures can be adjusted, thereby increasing or decreasing the unit area ratio of the light guide microstructures according to the required light output. This can improve the corner shadow problem of the light guide plate (backlight module) and meet the requirements for light output uniformity. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The following detailed description and accompanying drawings will provide an understanding of the present invention. It should be noted that various features are not drawn to scale as is standard in industry practice. In fact, the dimensions of various features may be arbitrarily increased or decreased for clarity of discussion.

[0023] FIG. 1 is a perspective view of a backlight module according to an embodiment of the present invention.

[0024] FIG. 2A is a diagram illustrating the luminous intensity distribution of the light emitting surface of the light guide plate of a control group backlight module.

[0025] FIG. 2B is a diagram illustrating a luminous intensity distribution diagram of a light emitting surface of a light guide plate of a backlight module according to an embodiment of the present invention.

[0026] FIG. 2C is a diagram illustrating a luminous intensity distribution diagram of a light emitting surface of a light guide plate of a backlight module according to another embodiment of the present invention.

[0027] FIG. 2D is a diagram illustrating a luminous intensity distribution diagram of a light emitting surface of a light guide plate of a backlight module according to another embodiment of the present invention.

[0028] FIG. 3A is a top view of the bottom surface of the light guide plate of the control group in FIG. 2A omitting the light guide microstructure.

[0029] FIG. 3B is a top view of the bottom surface of the light guide plate in FIG. 2C according to the embodiment of the present invention.

[0030] FIG. 4 is a perspective view of a backlight module according to another embodiment of the present invention.

[0031] FIG. 5 is a three-dimensional view of a backlight module according to another embodiment of the present invention.

[0032] FIG. 6 is a partial cross-sectional view of the backlight module of FIG. 5 along line segment AA.

[0033] FIG. 7 is a schematic diagram of a display according to an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In the following text, in order to clearly present the technical features of this case, the dimensions (e.g., length, width, thickness, and depth) of the elements (e.g., layers, films, substrates, and regions) in the drawings will be enlarged in a non-proportional manner, and the number of some elements will be reduced. Therefore, the description and explanation of the embodiments below are not limited to the number of elements in the drawings and the dimensions and shapes presented by the elements, but should cover the dimensions, shapes, and deviations from the two caused by actual processes and / or tolerances. Therefore, the elements presented in the drawings of this case are mainly for illustration and are not intended to accurately depict the actual shapes of the elements, nor are they intended to limit the scope of the patent application of this case.

[0035] Secondly, the words "about," "approximately," or "substantially" that appear in the present case not only cover the numerical values ​​and numerical ranges that are clearly stated, but also cover the permissible deviation range that can be understood by a person of ordinary skill in the technical field to which the invention belongs, wherein this deviation range can be determined by the error generated during measurement, and this error is, for example, caused by limitations of the measurement system or process conditions. In addition, "about" can mean within one or more standard deviations of the above-mentioned numerical value, such as ±5%, ±3%, or ±1%. The words "about," "approximately," or "substantially" that appear in this text can select an acceptable deviation range or standard deviation based on the optical properties, etching properties, mechanical properties, or other properties, and do not apply a single standard deviation to all properties such as the above-mentioned optical properties, etching properties, mechanical properties, and other properties.

[0036] Please refer to Figure 1. The backlight module 100 of at least one embodiment of the present disclosure includes a light source 120 and a light guide plate 140, and the light guide plate 140 is used to couple with the light source 120. The light guide plate 140 can be a light-transmitting plate or other equivalent light-transmitting components, and includes a light incident surface 140i, a light emitting surface 140e, a bottom surface 142, a plurality of strip-shaped microstructures 144, and a plurality of light-guiding microstructures 146. In Figure 1, the light guide plate 140 is presented upside down, so that the bottom surface 142 faces upward and the light emitting surface 140e faces downward. The light source 120 is adjacent to the light incident surface 140i, and the light L1 emitted by the light source 120 enters the light guide plate 140 from the light incident surface 140i.

[0037] The light-emitting surface 140e is adjacent to the light-incident surface 140i, while the bottom surface 142 is disposed opposite the light-emitting surface 140e. The light-incident surface 140i is connected between the light-emitting surface 140e and the bottom surface 142. In other words, the opposing sides S41 and S43 of the light-incident surface 140i are respectively connected to one side of the light-emitting surface 140e and one side of the bottom surface 142. Notably, the opposing sides S42 and S44 of the light-incident surface 140i are aligned with the opposing sides S22 and S24 of the light source 120, respectively.

[0038] For example, the light source 120 can be a light emitting diode (LED) light bar, an electroluminescence (EL) element, or a cold cathode fluorescent lamp (CCFL). In an embodiment where the light source 120 is an LED light bar, a plurality of LED elements are arranged in a row along the extension direction of the light incident surface 140i (i.e., direction D1). Preferably, the light source 120 can correspond to two opposite sides S42 and S44 of the light incident surface 140i, and the LED elements in this row of LEDs are arranged at equal distances. Each LED element of the LED light bar forms a point light source, and these point light sources are arranged in a uniformly distributed manner to form a line light source, wherein the outermost LED elements are roughly aligned with the two opposite sides S42 and S44 of the light incident surface 140i, respectively, but the outermost LED elements are not limited to being absolutely aligned with the two opposite sides S42 and S44 of the light incident surface 140i.

[0039] The bottom surface 142 has a central block 142c and two peripheral blocks 142r. The central block 142c is located between the two peripheral blocks 142r, and the central block 142c and the peripheral blocks 142r are arranged along direction D1. A plurality of strip-shaped microstructures 144 are disposed on the bottom surface 142 and distributed within the central block 142c and the peripheral blocks 142r of the bottom surface 142. Each strip-shaped microstructure 144 extends along direction D2, and direction D1 intersects direction D2, that is, directions D1 and D2 are not parallel. In some embodiments of the present invention, the light incident surface 140i can be perpendicular to direction D2, and direction D2 can be perpendicular to direction D1. In other words, the strip-shaped microstructures 144 can run perpendicular to the light incident surface 140i, but the present invention is not limited to this.

[0040] On the other hand, a plurality of light-guiding microstructures 146 are disposed on the bottom surface 142, with at least one light-guiding microstructure 146 located between any two adjacent stripe-shaped microstructures 144. Each light-guiding microstructure 146 extends along direction D1. Furthermore, the plurality of light-guiding microstructures 146 can be arranged in a row along a reference line (not shown). This reference line extends along direction D1, with the stripe-shaped microstructures 144 on the bottom surface 142 intersecting the reference line. In other words, the light-guiding microstructures 146 are tangential to the perimeter of the stripe-shaped microstructures 144.

[0041] After the light L1 enters the light guide plate 140 from the light incident surface 140i, the direction of travel of the light L1 can be changed by the light guide microstructure 146 located on the bottom surface 142, and the light L1 can be made to leave the light guide plate 140 from the light exit surface 140e. Accordingly, the present invention adjusts the unit area ratio of the light guide microstructure 146 to a larger extent, so that more light is emitted from the light exit surface 140e. In addition, compared with the prior art design without the light guide microstructure 146, for example, when applied to an optical film, the lack of the light guide microstructure 146 means that there is a flat area between the strip microstructures 144. When the light passes through each flat area, it will produce an effect of diffusing the light and emit it toward both sides, thereby widening the viewing angle. Therefore, this prior art design cannot adjust the amount of light emitted from the front and back of the light exit surface 140e.

[0042] The unit area ratio of the light-guiding microstructure 146 in the central block 142c is greater than the unit area ratio of the light-guiding microstructure 146 in the peripheral block 142r. It is worth noting that the unit area ratio of the light-guiding microstructure 146 as described herein refers to the ratio of the area of ​​the light-guiding microstructure 146 perpendicularly projected onto the light-emitting surface 140e along the normal to the light-emitting surface 140e, within a unit area of ​​the bottom surface 142. Specifically, in this embodiment, the bottom surface 142 can be divided into a plurality of unit areas 142u, and the ratio between the perpendicular projected area of ​​the light-guiding microstructure 146 located on each unit area 142u and the unit area 142u is the unit area ratio of the light-guiding microstructure 146.

[0043] For example, the light guide plate 140 in FIG1 has a central baseline (e.g., section line AA). The area enclosed along direction D2 between the two strip-shaped microstructures 144 closest to the central baseline on the bottom surface 142 of the light guide plate 140 is defined as a unit area 142u. The light guide microstructures 146 within this unit area 142u have a first projected area (not labeled). On the other hand, another similar unit area is enclosed on one side of the bottom surface 142 of the light guide plate 140, further away from the central baseline (i.e., the left side in FIG1 ). The light guide microstructures 146 within this left unit area 142u have a second projected area (not labeled). The first projected area of ​​the light guide microstructures 146 within the central area 142c is greater than the second projected area of ​​the light guide microstructures 146 within the peripheral area 142r.

[0044] Generally speaking, the point light sources of the LEDs light strips in the edge-entry backlight module are arranged in a uniformly distributed manner on the side of the light guide plate. Compared with the peripheral block 142r of the light guide plate, the central block 142c of the light guide plate can receive more light emitted by the point light sources. In detail, the central block 142c can not only receive the light emitted from the point light source in the center of the light incident surface, but also receive the light emitted from the point light sources on both sides of the light incident surface. However, the peripheral block 142r of the light guide plate can only receive the light emitted from the point light source on one side of the light incident surface and a part of the light emitted from the point light source in the center of the light incident surface, so that the amount of light incident on the peripheral block 142r is less than the amount of light incident on the central block 142c, thereby generating a corner dark band problem in the area away from the light source on the light exit surface of the light guide plate.

[0045] Therefore, the present invention improves the light output rate of the front and rear sections of the peripheral blocks on both sides of the light guide plate by adjusting the unit area ratio of the light guide microstructures in each area of ​​the bottom surface of the light guide plate. Please refer to Figure 2A to depict the luminous intensity distribution of the light output surface of the light guide plate of the control group backlight module, wherein the bottom boundary in Figure 2A represents the light incident surface of the light guide plate. The difference between the control group backlight module of Figure 2A and the above-mentioned backlight module 100 is that: in the control group backlight module of Figure 2A, the unit area ratio of the light guide microstructures in each area of ​​the bottom surface of the light guide plate is the same. For example, the shape (including width and height, etc.) of each light guide microstructure is the same, and the spacing between them is also the same.

[0046] As can be seen from FIG2A , the light emitting situation of the light emitting surface of the light guide plate (of the backlight module) is as follows: after the light L1 emitted by the light source enters the light guide plate, most of the light has been emitted from the light emitting surface of the light guide plate in the first two-thirds from the light incident surface (i.e., areas R1 and R2). As it moves further away from the light incident surface, the luminance of the area R3 in the last one-third of the light incident surface has obviously decreased, and is more concentrated in the central block of the light emitting surface of the light guide plate (where the darker the grayscale, the stronger the light, and the lighter the grayscale, the weaker the light). The light emitting efficiency of the two corners in the upper left and upper right corners of FIG2A (indicated by the arrow P1) is low, so that the light attenuation degree of the areas on both sides of the light guide plate is greater than the light attenuation degree of the central area of ​​the light guide plate, resulting in insufficient luminance in the two corners. In particular, in the area R3 in the last one-third of the light incident surface, the problem of dark shadows in the corners of the light emitting surface occurs.

[0047] As mentioned above, the light-guiding microstructure 146 of the present invention is the main structure for guiding the light in the light guide plate 140 to the light-emitting surface 140e for light emission. On this basis, in order to improve the dark angle problem of the light-emitting surface of the aforementioned light guide plate in the rear third area R3, the backlight module 100 of at least one embodiment of the present invention provides different designs of light-guiding microstructures 146 and strip microstructures 144 to adjust the unit area ratio of the light-guiding microstructures 146 in each area on the light guide plate 140, thereby enabling the light guide plate 140 to achieve the light emission condition of the light-emitting surface as shown in Figure 2B.

[0048] Referring to FIG. 2B , in at least one embodiment of the backlight module 100 of the present invention, the unit area ratio of the light-guiding microstructures 146 located in the peripheral block 142 r is smaller than the unit area ratio of the light-guiding microstructures 146 located in the central block 142 c. Because the smaller the unit area ratio of the light-guiding microstructures 146, the less light is emitted from the light-emitting surface. Therefore, less light is emitted from the light-emitting surface 140 e located in the peripheral block 142 r. Therefore, the amount of light L1 emitted from the light-emitting surface 140e near the light-entering surface 140i can be reduced, allowing more light L1 to be transmitted along the direction D2 to the area away from the light-entering surface 140i, that is, the amount of light L1 emitted from the light-emitting surface 140e away from the light-entering surface 140i is increased, so that most of the light L1 can be retained on the light-emitting surface 140e at the rear two-thirds of the distance from the light-entering surface 140i (i.e., areas R2 and R3) to emit light, thereby ensuring that the brightness of the central area of ​​the main display screen is sufficient and ensuring that the light on both sides of the light-emitting surface 140e of the light guide plate 140 can reach the corners on both sides away from the light-entering surface 140i. Therefore, compared with the control group of Figure 2A, the luminance of the backlight module 100 of the present invention at the corner of the rear one-third area R3 away from the light-entering surface 140i is improved. In addition, the light output luminance can be improved by approximately 6.4% compared with the control group of Figure 2A.

[0049] In other words, the light L1 enters the light guide plate 140 (not shown in FIG. 2B ) from the bottom of FIG. 2B and travels along the direction D2 to emit light. As the distance from the light incident surface (i.e., the distance from the bottom boundary of FIG. 2B ) increases, the emitted light is significantly enhanced. It is particularly noteworthy that the white area located inside the dark area (i.e., the upper middle right area within the dark area) is the area with the highest brightness. As can be seen from the comparison results of FIG. 2A and FIG. 2B , in at least one embodiment of the present invention, the problem of excessive light emission in the front one-third area R1 on the light-emitting surface 140e of the light guide plate 140 (from the light-entering surface 140i) and dark corners in the back one-third area R3 can be solved by making the unit area ratio of the light-guiding microstructure 146 in the central block 142c greater than the unit area ratio of the light-guiding microstructure 146 in the peripheral block 142r, and the overall brightness of the light can be improved. Furthermore, by aligning the opposing sides S42 and S44 of the light incident surface 140i with the opposing sides S22 and S24 of the light source 120, this configuration addresses the issue of excessive light emanating from the front third region R1 between the two sides S42 and S44, thereby reducing the amount of light emitted from the light emitting surface 140e between the two sides S42 and S44 adjacent to the light incident surface 140i. Prior art designs utilize locally distributed dimming structures near the light incident surface to disperse the light path. However, compared to at least one embodiment of the present invention, these prior art designs cannot achieve the aforementioned effect of reducing the amount of light emitted between the two sides S42 and S44 of the light incident surface 140i.

[0050] It is worth noting that, because the stripe-shaped microstructures 144 and the light-guiding microstructures 146 are arranged in a cross-sectional configuration, the unit area ratio of the light-guiding microstructures 146 is affected by the three-dimensional shape (including the radius of curvature, width, or height) of the stripe-shaped microstructures 144 or the spacing between two adjacent stripe-shaped microstructures 144. Specifically, in the embodiment of FIG1 , each stripe-shaped microstructure 144 has a surface 144s, and each light-guiding microstructure 146 has a surface 146s, wherein these surfaces 144s and 146s protrude from the bottom surface 142 of the light guide plate 140. The surface 144s of the stripe-shaped microstructure 144 is a cylindrical curved surface, while the surface 146s of the light-guiding microstructure 146 is two adjacent lateral faces of a triangular prism.

[0051] In this embodiment, each stripe-shaped microstructure 144 has a width w1. When the curvature radius and height of each stripe-shaped microstructure 144 are the same, the width w1 of each stripe-shaped microstructure 144 is the same. Furthermore, a spacing g1 is defined between adjacent stripe-shaped microstructures 144 (this spacing g1 is the distance between the edges of two adjacent stripe-shaped microstructures 144). Furthermore, the spacing g1 within each central region 142c is greater than the spacing g1 within each peripheral region 142r. Consequently, the light-guiding microstructure 146 within the central region 142c accounts for a greater percentage per unit area than the light-guiding microstructure 146 within the peripheral region 142r.

[0052] However, the width of each strip microstructure and the spacing between two adjacent strip microstructures in the present invention are not limited thereto. In another embodiment, the widths of at least two strip microstructures may also be different. For example, referring to FIG4 , the spacing g4 between two adjacent strip microstructures 444 (this spacing g4 is the distance between the center lines of the two adjacent strip microstructures 444) is the same. Each strip microstructure 444 of the backlight module 400 has a width w4, and when the height h4 of each strip microstructure 444 is the same, the width w4 of the strip microstructure 444 can be changed by changing the curvature radius of the strip microstructure 444.

[0053] Specifically, each stripe-shaped microstructure 444 has a cylindrical surface (not labeled), and therefore each stripe-shaped microstructure 444 also has a radius of curvature (i.e., the radius of curvature of the cylindrical surface described above). The radius of curvature of the stripe-shaped microstructure 444 located in the central block 442c is smaller than the radius of curvature of the stripe-shaped microstructure 444 located in the peripheral block 442r. Therefore, the width w4 of the stripe-shaped microstructure 444 located in the central block 442c is smaller than the width w4 of the stripe-shaped microstructure 444 located in the peripheral block 442r. In this way, the unit area ratio of the light-guiding microstructure 446 in the central block 442c is greater than the unit area ratio of the light-guiding microstructure 446 in the peripheral block 442r.

[0054] However, the height of each stripe microstructure in the present invention is not limited to the above, and the height of each stripe microstructure may also be different. For example, although not shown in the figure, in some embodiments of the present invention, when the width w4 of the stripe microstructures 444 is equal, the height h4 of the stripe microstructures 444 can be changed by changing the curvature radius of the stripe microstructures 444.

[0055] Referring back to FIG. 1 , in at least one embodiment of the present invention, the spacing g1 may decrease along the center section 142c toward the peripheral sections 142r. Specifically, the spacing g1 is greatest at the centerline closest to the center section 142c and gradually decreases as the distance from the center section 142c increases, ultimately reaching the smallest spacing g1 at the centerline farthest from the center section 142c.

[0056] Of particular note, as shown in FIG2B , by adjusting the unit area ratio of the light-guiding microstructures 146 in the central block 142c and the peripheral block 142r, the vignetting problem in the rear third region R3 from the light-entering surface 140i can be improved. However, since much light is delayed until the light-emitting surface 140e is located at the rear two-thirds of the distance from the light-entering surface 140i, the light output from the corners of the front third region R1 (indicated by arrow P2) is relatively low, and the light uniformity is approximately 77%.

[0057] In another embodiment, to ensure uniform light distribution across the entire light-emitting surface, the bottom surface 142 of the light guide plate 140 further includes a dot microstructure 305, as shown in FIG3B . For example, the dot microstructure 305 can be disposed on the stripe microstructure 144, the light-guiding microstructure 146, or the unstructured area of ​​the bottom surface 142 . The dot microstructure 305 can be in the form of convex dots or concave holes, and the dot microstructure 305 is distributed from dense to sparse along a direction away from the light-incident surface 140 i (i.e., along direction D2 ). Referring also to FIG2C , in a specific embodiment, to further adjust the situation where light is excessively concentrated at two-thirds of the distance between the light-emitting surface 140 e and the light-incident surface 140 i and to improve light uniformity, the dot microstructure 305 in this embodiment is generally distributed within the first third region R1 of the distance from the light-incident surface 140 i . This serves to fine-tune the light output within the first third region R1 of the light guide plate 140 .

[0058] Please refer to Figure 3A (i.e., the top view of the bottom surface of the light guide plate of the control group in Figure 2A omitting the light guide microstructure). Compared to this embodiment, the bottom surface 342 of the light guide plate 340 of the control group backlight module is provided with a dot microstructure 305'. The distribution of the dot microstructure 305' is sparse to dense along the direction D2 away from the point light source. The purpose is to increase the amount of light output as the position moves away from the light source. This is not only opposite to the distribution trend of the dot microstructure 305 in this embodiment, but the distribution range also covers the entire bottom surface 342.

[0059] The dot microstructure 305 disrupts total internal reflection in a small portion of the light guide plate 140, allowing some light to be emitted earlier in the region R1 of the light-emitting surface 140e, the first third of the distance from the light-entering surface 140i. This balances the problem of light being concentrated in the region R3 of the last two-thirds of the distance from the light-entering surface 140e. Referring to FIG2C , after adding the dot microstructure 305 and adjusting the light output locally, the light output from the light-emitting surface 140e of the light guide plate 140 is more uniform, achieving a light uniformity of approximately 85%, while improving the luminance by approximately 7.5% compared to the control group in FIG2A .

[0060] In addition to the aforementioned arrangement of the dot microstructure 305, light concentration can also be adjusted (i.e., light output is less likely to be overly concentrated at a point two-thirds of the way from the light-emitting surface 140e to the light-entering surface 140i) and the uniformity of light output can be improved. Referring to another embodiment of FIG5 and the luminous intensity distribution of the light-emitting surface of this embodiment in FIG2D , in this embodiment, a spacing g5 is provided between adjacent light-guiding microstructures 546 of the backlight module 500, and this spacing g5 decreases as it moves away from the light-entering surface 540i (i.e., along direction D2). In this way, when the light L1 enters the light guide plate 540 and moves along the direction D2, the light guide microstructures 546 that the light L1 contacts increase from few to many, and the amount of light output gradually increases. This changes the light output efficiency of the light L1 along the direction D2 after entering the light guide plate 540, so as to distribute the brightness of the overall light output surface 540e, thereby increasing the brightness by 8.9% compared to the control group in Figure 2A, and the light output uniformity can reach approximately 85%.

[0061] In some embodiments of the present invention, the unit area ratio of the light-guiding microstructure 146 can conform to a normal distribution in the direction D1. In other words, the unit area ratio of the light-guiding microstructure 146 presents a normal distribution along the direction from left to right in Figure 1. In order to cope with the lower light energy in the peripheral block 142r, this embodiment needs to reduce the light output in the front third of the peripheral block 142r from the light incident surface 140i, while retaining enough energy to release the remaining light in the rear third of the light incident surface 140i. Therefore, the unit area ratio of the light-guiding microstructure 146 in this embodiment is determined according to the light energy distribution in a predetermined direction (such as direction D1), and the light output can be fine-tuned to achieve the effect of overall uniform light output. In addition, in this embodiment, the aforementioned dot microstructure is distributed in a sparse to dense trend from the center to the edge. In this way, the light output uniformity of the light guide plate 140 can be made more in line with the requirements.

[0062] The above-mentioned embodiments of the present invention can be applied to light guide plates with a thickness ranging from 0.4 mm to 2.4 mm. Although the surface of each strip-shaped microstructure and light guide microstructure in the above-mentioned embodiments is protruding from the bottom surface of the light guide plate, it is not only easier to form and manufacture, but also the protruding structure can be used to reduce problems such as poor light quality caused by film adsorption (for example, dark lines), so it is preferably applied to light guide plates with a thinner thickness, such as light guide plates with a thickness ranging from 0.4 mm to 0.6 mm. However, the present invention is not limited to this. In various other embodiments, the surface of each strip-shaped microstructure and light guide microstructure can also be recessed in the bottom surface of the light guide plate. The light guide plate in which the surface of this light guide microstructure is recessed in the bottom surface of the light guide plate not only has the advantage of being easy to form, but is also suitable for light guide plates with a larger thickness range (for example, 1.8 mm to 2.4 mm or more) for application in vehicle-mounted displays.

[0063] 5 and 6 , in some embodiments, each light-guiding microstructure 546 includes at least two asymmetrical reflective planes 540 a and 540 b (i.e., each triangular prism-shaped light-guiding microstructure 546 has a surface formed by two side surfaces of different areas). These two reflective planes 540 a and 540 b form angles α and β with the bottom surface 542 , respectively. The angles α and β can be designed based on the angle of light entering the light guide plate 540 .

[0064] It should be noted that the light reflected by reflective planes 540a and 540b exhibits directionality based on the principle of incident angle and reflection angle, thus improving the overall brightness of the light guide plate. In one embodiment, angle α is closer to light incident surface 540i than angle β, and angle α is greater than angle β. That is, when light enters from the left in Figure 5 and encounters reflective plane 540b with a smaller angle, it is reflected and emitted toward light output surface 540e.

[0065] The shape of each light-guiding microstructure 146 also changes with the angles α and β, and the vertical height between the top and bottom surface 142 of each light-guiding microstructure 146 also changes. It is worth noting that in various embodiments of the present invention, the cross-sectional profiles of the stripe microstructures 144 and the light-guiding microstructures 146 can be profiles formed by, for example, an R-knife, a V-knife, a flat knife, or a polycrystalline knife.

[0066] Referring to FIG. 7 , a display 70 includes a backlight module 700 and a display panel 710. The display panel 710 is disposed relative to the backlight module 700 and is located above the light-emitting surface of the backlight module 700, so that the backlight module 700 can emit light toward the display panel 710. The backlight module 700 can be the backlight module 100, 300, or 400 described in the aforementioned embodiments, and the display panel 710 can be a transmissive display panel, such as a liquid crystal display panel. The light guide plate of the backlight module 700 can promote uniform emission of light L1, thereby improving the uniformity of the display panel 710.

[0067] In summary, the present invention utilizes strip microstructures and light-guiding microstructures cross-arranged on the bottom surface of the light guide plate to achieve control of the light output of the light guide plate near or far from the light source. In detail, the unit area ratio of the light guide microstructure is adjusted by changing the configuration and shape of the strip microstructure and the light guide microstructure, so that the unit area ratio of the light guide microstructure can be increased or decreased as the amount of light output is required. For example, the unit area ratio of the light guide microstructure located in the central area of ​​the bottom surface is greater than the unit area ratio of the light guide microstructure located in the peripheral area of ​​the bottom surface. In this way, the corner shadow problem of the light guide plate (backlight module) can be improved, thereby meeting the demand for light output uniformity.

[0068] Although the present invention has been disclosed above with reference to the embodiments, they are not intended to limit the present invention. Those skilled in the art may make modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

[0069]

Explanation of symbols

[0070] 100, 400, 500, 700: Backlight module

[0071] 120: Light source

[0072] 140: Light guide plate

[0073] 140a, 140b: Reflection planes

[0074] 140e: light-emitting surface

[0075] 140i, 540i: light incident side

[0076] 140s, 144s, 146s, 546s: Surface

[0077] 142: Bottom

[0078] 142c, 442c, 542c: Central blocks

[0079] 142r, 442r, 542r: surrounding blocks

[0080] 142u: unit area

[0081] 144, 444, 544: Stripe microstructure

[0082] 146, 446, 546: Light-guiding microstructures

[0083] 540a, 540b: Reflection planes

[0084] 305: Dot microstructure

[0085] 70: Display

[0086] 710: Display panel

[0087] AA: Line segment

[0088] D1, D2: direction

[0089] g1, g4, g5: spacing

[0090] h4: height

[0091] L1: Light

[0092] P1, P2: Arrow

[0093] R1, R2, R3: Area

[0094] S22, S24, S41, S42, S43, S44: Edge

[0095] w1, w4: width

[0096] α, β: angle.

Claims

1. A backlight module having a light-guiding microstructure with a sparse-dense distribution characteristic, comprising: light source; and A light guide plate is used to couple with the light source, and the light guide plate includes a light incident surface, wherein the light source is adjacent to the light incident surface, and light emitted by the light source enters the light guide plate from the light incident surface, wherein two opposite sides of the light incident surface are respectively aligned with two opposite sides of the light source; a light emitting surface, adjacent to the light incident surface; a bottom surface disposed opposite to the light emitting surface, wherein the light incident surface is connected between the light emitting surface and the bottom surface, and the bottom surface has a central block and two peripheral blocks, wherein the central block is located between a plurality of peripheral blocks, and the central block and the plurality of peripheral blocks are arranged along a first direction; a plurality of strip-shaped microstructures disposed on the bottom surface and distributed in the central block and the plurality of peripheral blocks, wherein each of the plurality of strip-shaped microstructures extends along a second direction, and the first direction intersects the second direction; as well as a plurality of light-guiding microstructures disposed on the bottom surface, wherein at least one of the plurality of light-guiding microstructures is located between any two adjacent ones of the plurality of strip-shaped microstructures, wherein each of the plurality of light-guiding microstructures extends along the first direction; The unit area ratio of the plurality of light-guiding microstructures in the central block is greater than the unit area ratio of the plurality of light-guiding microstructures in the plurality of peripheral blocks.

2. The backlight module having a sparse-dense distribution characteristic of light-guiding microstructures as claimed in claim 1 , wherein a spacing exists between two adjacent strip-shaped microstructures, and each of the spacings in the central block is larger than any of the spacings in the peripheral blocks. 3 . The backlight module having a sparse-dense distribution characteristic of light-guiding microstructures as claimed in claim 2 , wherein each of the plurality of strip-shaped microstructures has a width, and the widths of the plurality of strip-shaped microstructures are the same. 4 . The backlight module having a light-guiding microstructure with a sparse-dense distribution characteristic as claimed in claim 2 , wherein the plurality of intervals decrease gradually from the central block toward the plurality of peripheral blocks. 5 . The backlight module having a sparse-dense distribution characteristic of light-guiding microstructures according to claim 4 , wherein the unit area proportions of the plurality of light-guiding microstructures in the first direction conform to a normal distribution. 6 . The backlight module with light-guiding microstructures having a sparse-dense distribution characteristic as claimed in claim 1 , wherein the light incident surface is perpendicular to the second direction, and the second direction is perpendicular to the first direction. 7 . The backlight module with light guide microstructures having a sparse-dense distribution characteristic as claimed in claim 1 , wherein each of the plurality of strip-shaped microstructures and the plurality of light guide microstructures has a surface protruding from the bottom surface of the light guide plate. 8 . The backlight module having a sparse-dense distribution characteristic of light guide microstructures as claimed in claim 1 , wherein each of the plurality of strip-shaped microstructures and the plurality of light guide microstructures has a surface, and the surface is recessed in the bottom surface of the light guide plate.

9. The backlight module having a sparse-dense distribution characteristic of the light-guiding microstructure as described in claim 1, wherein each of the plurality of strip microstructures has a curvature radius, and the plurality of curvature radii of the plurality of strip microstructures located in the central block are smaller than the plurality of curvature radii of the plurality of strip microstructures located in the plurality of peripheral blocks.

10. The backlight module having a sparse-dense distribution characteristic of light-guiding microstructures as claimed in claim 1, wherein each of the plurality of strip microstructures has a width, and the widths of the plurality of strip microstructures located in the central block are smaller than the widths of the plurality of strip microstructures located in the plurality of peripheral blocks. 11 . The backlight module having light-guiding microstructures with sparse and dense distribution characteristics as claimed in claim 1 , wherein each of the plurality of light-guiding microstructures comprises at least two mutually asymmetric reflective planes. 12 . The backlight module with light-guiding microstructures having a sparse-dense distribution characteristic as claimed in claim 1 , wherein a spacing exists between two adjacent light-guiding microstructures, and the spacings decrease in a direction away from the light incident surface.

13. The backlight module having a light guide microstructure with a sparse-dense distribution characteristic as claimed in claim 1, wherein the light guide plate further comprises: A plurality of dot microstructures are disposed on the bottom surface, and the distribution of the plurality of dot microstructures along the second direction is dense to sparse. 14 . The backlight module having a light-guiding microstructure with a sparse-dense distribution characteristic as claimed in claim 13 , wherein the plurality of lattice dot microstructures are distributed in a front third area from the light incident surface.

15. A display comprising: A backlight module having a light-guiding microstructure with a sparse-dense distribution characteristic according to any one of claims 1 to 14; and The display panel is arranged relative to the backlight module having a sparse-dense distribution characteristic of the light-guiding microstructure.

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