TWI898641B - Backlight module and display device - Google Patents

Abstract

A backlight module including a light source and a light guide plate used for coupling the light source is provided. The light guide plate includes a light incident surface, a light exiting surface adjacent to the light incident surface, a bottom surface, a plurality of string microstructures and a plurality of light guide microstructures. A light ray emitted from the light source enters the light guide plate from the light incident surface, and two opposite sides of the light incident surface are aligned to two opposite sides of the light source. The bottom surface has two surrounding regions and a center region located between the surrounding regions, while these three regions are aligned along a first direction. Each of the string microstructures extends along a second direction which is intercrossed with the first direction. The light guide microstructures are located between any two adjacent string microstructures, and each of the light guide microstructures extends along the first direction. The unit area ratio of the light guide microstructures within the center region is larger than the unit area ratios of the light guide microstructures within the surrounding regions.

Description

Backlight unit and display

The present invention relates to a light emitting module, and in particular to a backlight module and a display using the backlight module.

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 and is emitted from the light emitting surface of the light guide plate. In order to allow the light rays 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 as it travels. When the attenuation of the areas near the two sides of the light guide plate is greater than the attenuation of the central area of the light guide plate, it will cause a dark shadow in the light emitting corner of the light guide plate away from the light incident surface.

Therefore, the present invention provides a backlight module that can improve the shadow problem in the light-emitting corners of the light guide plate, thereby meeting the demand for improving light-emitting uniformity.

The present invention also provides a display using the backlight module.

At least one embodiment of the present invention provides a backlight module comprising a light source and a light guide plate, the light guide plate being coupled to the light source and comprising a light incident surface, a light emitting surface adjacent to the light incident surface, and a bottom surface. 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, with opposite sides of the light incident surface aligned with opposite sides of the light source. The bottom surface is disposed opposite the light emitting surface, with the light incident surface connected between the light emitting surface and the bottom surface. The bottom surface has a central block and two peripheral blocks, with the central block being located between the two peripheral blocks, and the central block and the peripheral blocks being arranged along a first direction. The light guide plate further includes a plurality of stripe-shaped microstructures and light-guiding microstructures disposed on the bottom surface. The stripe-shaped microstructures are distributed within the central region and the peripheral region, and each stripe-shaped microstructure extends along a second direction, with the first direction intersecting the second direction. At least one light-guiding microstructure is located between any two adjacent stripe-shaped microstructures, and each light-guiding microstructure extends along the first direction. The light-guiding microstructures in the central region have a greater unit area ratio than those in the peripheral region.

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

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.

In one embodiment of the present invention, the spacing decreases from the central block toward the peripheral block.

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.

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.

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-guiding plate.

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-guiding plate.

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 microstructure located in the central area is smaller than the curvature radius of the strip-shaped microstructure located in the peripheral area.

In one embodiment of the present invention, each stripe-shaped microstructure has a width, and the width of the stripe-shaped microstructure located in the central area is smaller than the width of the stripe-shaped microstructure located in the peripheral area.

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

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-entering surface.

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

In one embodiment of the present invention, the light guide plate further includes a plurality of dot microstructures, which are arranged on the bottom surface and distributed within the front third of the area away from the light incident surface.

At least one embodiment of the present invention provides a display comprising the aforementioned backlight module and a display panel. The display panel is disposed opposite to the backlight module.

Based on the above, the present invention achieves control over the light output of the light guide plate by employing a cross-patterned strip microstructure and light-guiding microstructure on the bottom surface of the light guide plate. By varying the configuration and shape of the strip microstructure and light-guiding microstructure, the unit area ratio of the light-guiding microstructure can be adjusted, thereby increasing or decreasing the unit area ratio based on the required light output. This improves the corner shadowing problem of the light guide plate (of the backlight module) and meets the requirement for light output uniformity.

In the following text, to clearly present the technical features of this application, the dimensions (e.g., length, width, thickness, and depth) of the components (e.g., layers, films, substrates, and regions) in the drawings will be exaggerated in varying proportions, and the number of some components will be reduced. Therefore, the description and interpretation of the embodiments below are not limited to the number of components in the drawings or the dimensions and shapes presented by the components, but should include dimensions, shapes, and deviations therefrom caused by actual manufacturing processes and/or tolerances. Therefore, the components presented in the drawings of this application are primarily for illustration purposes and are not intended to accurately depict the actual shapes of the components, nor are they intended to limit the scope of the patent application of this application.

Second, the terms "approximately," "approximately," or "substantially" used in this case encompass not only the numerical values and numerical ranges explicitly stated, but also the permissible deviations understood by one of ordinary skill in the art to which the invention pertains. This deviation may be determined by measurement errors, such as those arising from limitations of the measurement system or process conditions. Furthermore, "approximately" may mean within one or more standard deviations of the numerical value, such as ±5%, ±3%, or ±1%. When used in this document, terms such as "approximately," "approximately," or "substantially" may be used to define acceptable deviations or standard deviations depending on the optical, etching, mechanical, or other properties. A single standard deviation is not intended to apply to all optical, etching, mechanical, or other properties.

Referring to FIG. 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 member, 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 FIG. 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 ray L1 emitted by the light source 120 enters the light guide plate 140 from the light incident surface 140i.

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 connected to one side of the light-emitting surface 140e and one side of the bottom surface 142, respectively. 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.

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 embodiments where the light source 120 is an LED light bar, multiple LED elements are arranged in a row along the direction of extension of the light incident surface 140i (i.e., direction D1). Preferably, the light source 120 corresponds to opposite sides S42 and S44 of the light incident surface 140i, with the LED elements in this row of LEDs arranged at equal distances from each other. Each LED element in the LED light strip forms a point light source, and these point light sources are evenly distributed to form a line light source. The outermost LED elements are roughly aligned with opposite sides S42 and S44 of the light incident surface 140i, but this is not limited to the outermost LED elements being absolutely aligned with opposite sides S42 and S44 of the light incident surface 140i.

The bottom surface 142 has a central region 142c and two peripheral regions 142r. The central region 142c is located between the two peripheral regions 142r, and the central region 142c and the peripheral regions 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 region 142c and the peripheral regions 142r of the bottom surface 142. Each strip-shaped microstructure 144 extends along direction D2, which intersects direction D1, meaning that 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 may be oriented perpendicular to the light incident surface 140 i , but the present invention is not limited thereto.

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 may 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.

After light L1 enters the light guide plate 140 from the light incident surface 140i, the light guiding microstructure 146 located on the bottom surface 142 can change the direction of light L1 and cause light L1 to leave the light guide plate 140 from the light exit surface 140e. Accordingly, the present invention increases the unit area ratio of the light guiding microstructure 146 by adjusting the light exit surface 140e to emit more light. In addition, compared to the previous technical design without the light guiding microstructure 146, for example, when applied to an optical film, the lack of the light guiding microstructure 146 means that there is a flat area between the strip microstructures 144. When 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 rear of the light emitting surface 140e.

The unit area ratio of the light-guiding microstructure 146 in the central region 142c is greater than the unit area ratio of the light-guiding microstructure 146 in the peripheral region 142r. It is worth noting that the unit area ratio of the light-guiding microstructure 146 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 to 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 vertical projection 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.

For example, the light guide plate 140 in FIG1 has a central reference line (e.g., section line segment A-A). The area enclosed along direction D2 between the two strip-shaped microstructures 144 closest to the central reference line on the bottom surface 142 of the light guide plate 140 is defined as a unit area 142u. The light-guiding microstructure 146 on this unit area 142u has a first projected area (not labeled). On the other hand, another identical unit area is circled on one side of the bottom surface 142 of the light guide plate 140, away from the central reference line (i.e., the left side in FIG1 ). It can be found that the light-guiding microstructure 146 on this left-side unit area 142u has a second projected area (not labeled), wherein the first projected area of the light-guiding microstructure 146 located in the central block 142c is larger than the second projected area of the light-guiding microstructure 146 located in the peripheral block 142r.

Generally speaking, the point light sources of LED strips in edge-lit backlight modules are evenly distributed along the sides of the light guide plate. Compared to the peripheral area 142r of the light guide plate, the central area 142c of the light guide plate receives more light from these point light sources. Specifically, the central area 142c receives light not only from the point light sources in the center of the light incident surface, but also from point light sources on both sides of the light incident surface. However, the peripheral block 142r of the light guide plate can only receive light emitted from a point light source on one side of the light incident surface and a portion of the light emitted from a point light source in the center of the light incident surface. As a result, the amount of light incident on the peripheral block 142r is less than the amount of light incident on the central block 142c, thereby causing a corner dark band problem in the area far from the light source on the light output surface of the light guide plate.

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 for a diagram of 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 in Figure 2A and the above-mentioned backlight module 100 is that: in the control group backlight module in 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 distance between them is also the same.

As shown in Figure 2A, the light output from the light guide plate (of the backlight module) is as follows: upon entering the light guide plate, light L1 emitted by the light source is mostly emitted from the first two-thirds of the light exit surface (i.e., regions R1 and R2) of the light exit surface. As light travels further away from the light entrance surface, the brightness of region R3, the last third of the light exit surface, decreases significantly, becoming more concentrated in the central area of the light exit surface (where darker grayscale indicates stronger light, and lighter grayscale indicates weaker light). The light extraction efficiency at the upper left and upper right corners of Figure 2A (indicated by arrows P1) is low, resulting in greater light attenuation on the sides of the light guide plate than in the center, resulting in insufficient brightness in these corners. In particular, dark shadows appear in the corners of the light-emitting surface, in the area R3, the last third of the light-emitting surface from the light-entering surface.

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 corner problem of the light-emitting surface of the 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.

Referring to FIG. 2B , in the backlight module 100 of at least one embodiment of the present invention, the light-guiding microstructures 146 located in the peripheral region 142r have a smaller unit area ratio than the light-guiding microstructures 146 located in the central region 142c. Because the smaller the unit area ratio of the light-guiding microstructures 146, the less light is emitted from the light-emitting surface. Consequently, less light is emitted from the light-emitting surface 140e located in the peripheral region 142r. 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 rays L1 to be transmitted along the direction D2 to the area far away from the light-entering surface 140i. That is, the amount of light L1 emitted from the light-emitting surface 140e far away from the light-entering surface 140i is increased, so that most of the light rays 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). This ensures sufficient brightness in the central area of the main display screen and ensures 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 far away from the light-entering surface 140i. Therefore, compared with the control group in FIG2A , the brightness of the corner of the rear third region R3 of the backlight module 100 of the present invention from the light incident surface 140i is improved. In addition, the light output brightness is improved by about 6.4% compared with the control group in FIG2A .

In other words, light ray L1 enters the light guide plate 140 (not shown in FIG2B ) from the bottom in FIG2B and travels out in direction D2 . The intensity of the outgoing light increases significantly as it moves away from the light entry surface (i.e., farther from the bottom edge of FIG2B ). Of particular note, the white area within the dark area (i.e., the upper center to the right of the dark area) is the brightest. As can be seen from the comparison results of Figures 2A and 2B, in at least one embodiment of the present invention, the problem of excessive light output from the front one-third area R1 of the light-emitting surface 140e of the light guide plate 140 (from the light-incident surface 140i) and dark corners in the rear one-third area R3 can be solved by having the unit area ratio of the light-guiding microstructures 146 in the central block 142c be greater than the unit area ratio of the light-guiding microstructures 146 in the peripheral block 142r, thereby helping to improve the overall light output brightness. 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 allows this embodiment to address the issue of excessive light output between the two sides S42 and S44 of the front third region R1, thereby reducing the amount of light emitted between the two sides S42 and S44 of the light emitting surface 140e 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 technical effect of reducing the amount of light emitted between the two sides S42 and S44 of the light incident surface 140i.

It is worth noting that, because the stripe 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 radius of curvature, width, or height) of the stripe microstructures 144 or the distance between two adjacent stripe microstructures 144. Specifically, in the embodiment of FIG1 , each stripe 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 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.

In this embodiment, each stripe-shaped microstructure 144 has a width w1. When the radius of curvature and height of each stripe-shaped microstructure 144 are identical, the width w1 of each stripe-shaped microstructure 144 is the same. Furthermore, a distance g1 is defined between two adjacent stripe-shaped microstructures 144 (this distance g1 is the distance between the edges of the two adjacent stripe-shaped microstructures 144). Furthermore, the distance g1 within each central region 142 c is greater than the distance g1 within each peripheral region 142 r. This ensures that the light-guiding microstructure 146 has a greater unit area ratio within the central region 142 c than within the peripheral region 142 r.

However, the width of each strip microstructure and the spacing between adjacent strip microstructures in the present invention are not limited thereto. In another embodiment, the widths of at least two strip microstructures may be different. For example, referring to FIG. 4 , the spacing g4 between two adjacent strip microstructures 444 (this spacing g4 is the distance between the centerlines of the two adjacent strip microstructures 444) is the same. Each strip microstructure 444 in the backlight module 400 has a width w4. While the height h4 of each strip microstructure 444 is the same, the width w4 of the strip microstructure 444 can be varied by changing the radius of curvature of the strip microstructure 444.

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 region 442c is smaller than the radius of curvature of the stripe-shaped microstructure 444 located in the peripheral region 442r. Therefore, the width w4 of the stripe-shaped microstructure 444 located in the central region 442c is smaller than the width w4 of the stripe-shaped microstructure 444 located in the peripheral region 442r. In this way, the unit area ratio of the light-guiding microstructure 446 in the central block 442c can be greater than the unit area ratio of the light-guiding microstructure 446 in the peripheral block 442r.

However, the height of each stripe microstructure in the present invention is not limited to the above; the height of each stripe microstructure may also vary. For example, although not shown in the figures, in some embodiments of the present invention, when the width w4 of each stripe microstructure 444 is equal, the height h4 of each stripe microstructure 444 can be varied by changing the radius of curvature of each stripe microstructure 444.

Referring back to FIG. 1 , in at least one embodiment of the present invention, the spacing g1 may decrease from the central block 142c toward the peripheral block 142r. Specifically, the spacing g1 is greatest at the centerline of the central block 142c and gradually decreases as the spacing distance from the centerline of the central block 142c increases, reaching its smallest position at the location farthest from the centerline of the central block 142c.

Of particular note, as shown in Figure 2B , by adjusting the unit area ratio of the light-guiding microstructures 146 in the central region 142c and the peripheral region 142r, the vignetting problem in the rear third of the light-entering surface 140i, R3, can be improved. However, since much of the light is delayed until the light-emitting surface 140e, located two-thirds of the distance from the light-entering surface 140i, the light output from the corners on both sides of the front third of the light-entering surface 140i, R1 (indicated by arrow P2), is less, and the light uniformity is approximately 77%.

In some other embodiments, to ensure even 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 microstructures 144, the light-guiding microstructures 146, or the unstructured area of the bottom surface 142. The dot microstructure 305 can be in the form of protrusions or recesses, and the distribution of the dot microstructure 305 is from dense to sparse along a direction away from the light-incoming surface 140i (i.e., along direction D2). Please refer to Figure 2C. In a specific embodiment, in order to further adjust the situation where the light output is excessively concentrated at two-thirds of the distance between the light output surface 140e and the light input surface 140i, and to improve the uniformity of the light output, the dot microstructure 305 in this embodiment is roughly distributed within the front one-third area R1 of the light input surface 140i. The purpose is to fine-tune the amount of light output within the front one-third area R1 of the light guide plate 140.

Please refer to Figure 3A (i.e., a 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 the present embodiment, the bottom surface 342 of the light guide plate 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 is farther away from the light source. Not only is the distribution trend of the dot microstructure 305 opposite to that of the present embodiment, but the distribution range also covers the entire bottom surface 342.

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 from the light-emitting surface 140e of the light guide plate 140, in the first third of the region R1 relative to the light-entering surface 140i. This balances the problem of light being concentrated in the last two-thirds of the region R3 of the light-emitting surface 140e. Referring to Figure 2C , 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 brightness by approximately 7.5% compared to the control group in Figure 2A .

In addition to the aforementioned arrangement of the dot microstructures 305, light concentration can also be adjusted (i.e., reducing the excessive concentration of light on the light-emitting surface 140e at a point two-thirds of the way from the light-entering surface 140i) and improving light uniformity. Referring to another embodiment in FIG5 and the light intensity distribution of the light-emitting surface of this embodiment in FIG2D , in this embodiment, a distance g5 is provided between two adjacent light-guiding microstructures 546 of the backlight module 500, and this distance g5 decreases in a direction away from the light-entering surface 540i (i.e., along direction D2). In this way, when light L1 enters the light guide plate 540 and advances along the direction D2, the number of light-guiding microstructures 546 that light L1 contacts increases from a small number to a large number, and the amount of light output gradually increases. This changes the light output efficiency of light L1 along the direction D2 after entering the light guide plate 540, thereby distributing the brightness of the entire light-emitting surface 540e, increasing the brightness by 8.9% compared to the control group in Figure 2A, and achieving a light output uniformity of approximately 85%.

In some embodiments of the present invention, the unit area ratio of the light-guiding microstructure 146 can conform to a normal distribution in direction D1. In other words, the unit area ratio of the light-guiding microstructure 146 exhibits a normal distribution along the direction from left to right in Figure 1. In order to address the lower light energy in the peripheral block 142r, this embodiment needs to reduce the light output in the peripheral block 142r in the first third of the distance from the light incident surface 140i, while retaining sufficient energy to release the remaining light in the last third of the distance from 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 (e.g., direction D1), and the light output can be fine-tuned to achieve an overall uniform light output effect. Furthermore, in this embodiment, the aforementioned dot microstructures are distributed in a sparse to dense trend from the center toward the edge. This allows the light output uniformity of the light guide plate 140 to better meet requirements.

The above-mentioned embodiments of the present invention can be applied to light guide plates with a thickness ranging from 0.4mm to 2.4mm. Although the surface of each strip-shaped microstructure and light-guiding microstructure in the above-mentioned embodiments protrudes from the bottom surface of the light guide plate, not only is the formation and manufacturing process easier, but the protruding structure can also be used to reduce problems such as poor light quality caused by film adsorption (for example, dark lines), and therefore it is preferably applied to thinner light guide plates, such as light guide plates with a thickness ranging from 0.4mm to 0.6mm. However, the present invention is not limited to this. In various other embodiments, the surface of each strip-shaped microstructure and light-guiding microstructure can also be recessed into the bottom surface of the light guide plate. The light guide plate with the surface of this light-guiding microstructure recessed from 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 wider thickness range (e.g., 1.8mm to 2.4mm or above), so as to be applied to automotive displays.

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

It's important to note that the light reflected by reflective planes 540a and 540b exhibits directivity based on the principles of incident and reflection angles, 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. This means that light entering from the left in Figure 5 is reflected by reflective plane 540b, which has a smaller angle, and exits toward light output surface 540e.

The shape of each light-guiding microstructure 146 also changes as the angles α and β change, 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 formed by, for example, an R-knife, a V-knife, a flat knife, or a polycrystalline knife.

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, 400, or 500 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.

In summary, the present invention utilizes strip microstructures and light-guiding microstructures cross-arranged on the bottom surface of a light guide plate to control the amount of light emitted by the light guide plate near or far from the light source. Specifically, by changing the configuration and shape of the strip microstructures and the light-guiding microstructures, the unit area ratio of the light-guiding microstructures can be adjusted, thereby increasing or decreasing the unit area ratio of the light-guiding microstructures according to the required light output. For example, the unit area ratio of the light-guiding microstructures located in the central area of the bottom surface can be greater than the unit area ratio of the light-guiding microstructures located in the peripheral area of the bottom surface. In this way, the corner shadow problem of the light guide plate (of the backlight module) can be improved, thereby meeting the requirement for light output uniformity.

Although the present invention has been disclosed above by way of 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 scope of the attached patent application.

100, 400, 500, 700: Backlight module 120: Light source 140, 540: Light guide plate 140e, 540e: Light exit surface 140i, 540i: Light incident surface 140s, 144s, 146s, 546s: Surface 142, 342, 542: Bottom surface 142c, 442c, 542c: Central area 142r, 442r, 542r: Peripheral area 142u: Unit area 144, 444, 544: Stripe microstructures 146, 446, 546: Light guide microstructures 540a, 540b: Reflective surface 305, 305': Dot microstructure 70: Display 710: Display panel A-A: Line segment D1, D2: Direction g1, g4, g5: Spacing h4: Height L1: Light ray P1, P2: Arrows R1, R2, R3: Area S22, S24, S41, S42, S43, S44: Sides w1, w4: Width α, β: Angle

The following detailed description, accompanied by accompanying drawings, will provide an understanding of the present invention. It should be noted that many features are not drawn to scale according to industry practice. In fact, the dimensions of various features may be arbitrarily increased or decreased for clarity of discussion. Figure 1 illustrates a perspective view of a backlight module according to one embodiment of the present invention. Figure 2A illustrates a luminous intensity distribution diagram of the light-emitting surface of a light guide plate (LGP) in a control set of backlight modules. Figure 2B illustrates a luminous intensity distribution diagram of the light-emitting surface of a LGP in a backlight module according to one embodiment of the present invention. Figure 2C illustrates a luminous intensity distribution diagram of the light-emitting surface of a LGP in a backlight module according to another embodiment of the present invention. Figure 2D illustrates a luminous intensity distribution diagram of the light-emitting surface of a LGP in a backlight module according to another embodiment of the present invention. Figure 3A shows a top view of the bottom surface of the light guide plate of the control group in Figure 2A, omitting the light-guiding microstructure. Figure 3B shows a top view of the bottom surface of the light guide plate of the embodiment of the present invention in Figure 2C. Figure 4 shows a perspective view of a backlight module according to another embodiment of the present invention. Figure 5 shows a perspective view of a backlight module according to another embodiment of the present invention. Figure 6 shows a partial cross-sectional view of the backlight module along line A-A of Figure 5. Figure 7 shows a schematic diagram of a display according to one embodiment of the present invention.

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100: Backlight module 120: Light source 140: Light guide plate 140e: Light exit surface 140i: Light incident surface 140s, 144s, 146s: Surface 142: Bottom surface 142c: Central region 142r: Peripheral region 142u: Unit area 144: Stripe microstructure 146: Light-guiding microstructure A-A: Line segment D1, D2: Direction g1: Pitch L1: Light line S22, S24, S41, S42, S43, S44: Sides w1: Width

Claims (14)

A backlight module comprises: a light source; and a light guide plate for coupling with the light source, wherein the light guide plate comprises: 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 exit surface, adjacent to the light incident surface; a bottom surface, opposite to the light exit surface, wherein the light incident surface is connected between the light exit surface and the bottom surface, and the bottom surface has a central block and two peripheral blocks, wherein the central block is located between the peripheral blocks, and the central block and the peripheral blocks are arranged along a first direction; a plurality of strip-shaped microstructures, which are arranged on the bottom surface and distributed in the central block. The invention relates to a substrate comprising: a central block and peripheral blocks, wherein each of the strip microstructures extends along a second direction, and the first direction intersects the second direction; and a plurality of light-guiding microstructures are disposed on the bottom surface, and at least one of the light-guiding microstructures is located between any two adjacent strip microstructures, wherein each of the light-guiding microstructures extends along the first direction; wherein 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; wherein each of the strip microstructures has a width, and the widths of the strip microstructures located in the central block are smaller than the widths of the strip microstructures located in the peripheral blocks. The backlight module as described in claim 1, wherein there is a distance between two adjacent strip-shaped microstructures, and each of the distances located in the central block is greater than any of the distances located in the peripheral blocks. The backlight module as described in claim 2, wherein each of the strip-shaped microstructures has a width, and the widths of the strip-shaped microstructures are the same. The backlight module as described in claim 2, wherein the intervals decrease along the direction from the central block toward the peripheral blocks. The backlight module as described in claim 4, wherein the unit area ratio of the light-guiding microstructures conforms to a normal distribution in the first direction. The backlight module as described in claim 1, wherein the light incident surface is perpendicular to the second direction, and the second direction is perpendicular to the first direction. The backlight module as described in claim 1, wherein 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-guiding plate. The backlight module as described in claim 1, wherein each of the strip-shaped microstructures and the light-guiding microstructures has a surface, and the surface is recessed in the bottom surface of the light-guiding plate. The backlight module as described in claim 1, wherein each of the light-guiding microstructures includes at least two mutually asymmetric reflective planes. In the backlight module of claim 1, there is a distance between two adjacent light-guiding microstructures, and the distances decrease in a direction away from the light incident surface. A backlight module comprises: a light source; and a light guide plate for coupling with the light source, wherein the light guide plate comprises: 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 exit surface, adjacent to the light incident surface; a bottom surface, opposite to the light exit surface, wherein the light incident surface is connected between the light exit surface and the bottom surface, and the bottom surface has a central block and two peripheral blocks, wherein the central block is located between the peripheral blocks, and the central block and the peripheral blocks are arranged along a first direction; a plurality of strip-shaped microstructures, which are arranged on the bottom surface , and are distributed in the central block and the peripheral blocks, wherein each of the strip microstructures extends along a second direction, and the first direction intersects the second direction; a plurality of light-guiding microstructures are disposed on the bottom surface, and at least one of the light-guiding microstructures is located between any two adjacent strip microstructures, wherein each of the light-guiding microstructures extends along the first direction; and a plurality of dot microstructures are disposed on the bottom surface, and the distribution of the dot microstructures is dense to sparse along the second direction; wherein 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. The backlight module as described in claim 11, wherein the dot microstructures are distributed within the front third area away from the light incident surface. A backlight module comprises: a light source; and a light guide plate for coupling with the light source, wherein the light guide plate comprises: 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 exit surface, adjacent to the light incident surface; a bottom surface, oppositely arranged to the light exit surface, wherein the light incident surface is connected between the light exit surface and the bottom surface, and the bottom surface has a central block and two peripheral blocks, wherein the central block is located between the peripheral blocks, and the central block and the peripheral blocks are arranged along a first direction; a plurality of strip-shaped microstructures, which are arranged on the bottom surface and distributed in the central block and adjacent to the bottom surface. The invention relates to a method for manufacturing a light-guiding microstructure comprising: providing a plurality of light-guiding microstructures disposed on the bottom surface, wherein each of the strip microstructures extends along a second direction and the first direction intersects the second direction; and providing a plurality of light-guiding microstructures disposed on the bottom surface, and at least one of the light-guiding microstructures is located between any two adjacent strip microstructures, wherein each of the light-guiding microstructures extends along the first direction; wherein 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; wherein each of the strip microstructures has a curvature radius, and the curvature radii of the strip microstructures located in the central block are smaller than the curvature radii of the strip microstructures located in the peripheral blocks. A display comprises: a backlight module as described in any one of claims 1 to 13; and a display panel arranged relative to the backlight module.