Backlight module having optical film on which multiple tapered structures are designed, and display device
Patent Information
- Application Number
- KR1020267030327
- Authority / Receiving Office
- KR · KR
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-04-01
- Filing Date
- 2022-05-31
- Publication Date
- 2026-09-21
Smart Images
Figure P1020267030327_ABST
Abstract
Description
Technology Field
[0001] The present invention relates to a backlight module and a display device having a plurality of conical structures designed on an optical film, and in particular to a side-light incident type backlight module and a display device including said side-light incident type backlight module. Background Technology
[0002] Conventional backlight modules generally include a diffusion sheet to homogenize light rays. Typically, currently used diffusion sheets contain multiple scattering particles, which can homogenize light rays by scattering and dispersing them. However, the aforementioned diffusion sheets containing scattering particles are used for defect concealment and have low optical directivity, which destroys the high directivity of the light guide plate. To improve directivity, the haze of the diffusion sheet must be reduced, but this compromises the defect concealment capability. In the case of brightness enhancement sheets, they help improve brightness; however, the haze of the upper and lower diffusion sheets used in backlight modules affects brightness and optical aesthetics, making it difficult to further improve the luminance of existing backlight modules. Therefore, the key to backlight module design is how to improve light concentration at the light emission viewing angle and brightness at the frontal viewing angle while maintaining defect concealment capabilities. means of solving the problem
[0003] One embodiment of the present invention provides a backlight module comprising an optical film capable of improving light concentration at the light emission viewing angle and brightness at the front viewing angle.
[0004] Another embodiment of the present invention provides a display device including the backlight module.
[0005] A backlight module provided by one embodiment of the present invention comprises a light guide plate, a light source, and an optical film. The light guide plate has an incoming surface and an outgoing surface, and the outgoing surface has a normal. The light source is installed adjacent to the incoming surface. The optical film is installed facing the outgoing surface and includes a plurality of parallel prisms and a plurality of microstructures. The extension direction of each prism is perpendicular to the normal, and each prism faces the outgoing surface of the light guide plate. Each microstructure is located on a surface of the optical film away from the light guide plate, and each microstructure is a conical structure having a plurality of facets. These prisms are located between these microstructures and the outgoing surface.
[0006] In one embodiment of the present invention, the backlight module further includes a plurality of prism sheets, and these optical films are positioned between these prism sheets and the light-emitting surface.
[0007] In one embodiment of the present invention, each prism sheet comprises a plurality of parallel prism strips, and the extension direction of these prism strips of one prism sheet is perpendicular to the extension direction of these prism strips of another prism sheet.
[0008] In one embodiment of the present invention, the light-emitting surface is connected to one side of the light-receiving surface. The light source comprises a plurality of light-emitting diodes arranged along a straight line, wherein the extension direction of the prism strips of one of the prism sheets is parallel to the straight line, and the extension direction of the prism strips of another prism sheet is perpendicular to the straight line.
[0009] In one embodiment of the present invention, the extension direction of these prisms is perpendicular to the straight line.
[0010] In one embodiment of the present invention, the light-emitting surface is connected to one side of the light-receiving surface, and the light source comprises a plurality of light-emitting diodes arranged along a straight line, and the extension direction of these prism strips of each prism sheet is neither parallel nor perpendicular to the straight line.
[0011] In one embodiment of the present invention, the extension direction of these prisms is parallel to the straight line.
[0012] In one embodiment of the present invention, these microstructures are a plurality of pyramid-shaped concave holes adjacent to each other.
[0013] In one embodiment of the present invention, these microstructures are a plurality of pyramid-shaped protrusions adjacent to each other.
[0014] In one embodiment of the present invention, these microstructures are arranged in an array obliquely with respect to the length of one side of the optical film.
[0015] In one embodiment of the present invention, the light guide plate has a bottom surface facing the light-emitting surface and a plurality of light guide structures formed on the bottom surface, and each light guide structure has a light-facing surface and a light-facing surface connected to each other. The light-facing surface faces the direction of light propagation of the light source, a first angle is formed between the light-facing surface and the bottom surface, and a second angle is formed between the light-facing surface and the bottom surface. Both the first angle and the second angle are acute angles, and the first angle is smaller than the second angle.
[0016] A display device provided by another embodiment of the present invention includes the backlight module and the display panel, wherein the display panel is installed opposite the backlight module. Effects of the invention
[0017] Based on the above, these prisms and these microstructures are used so that light rays emitted by a light source first pass through these prisms of the optical film to produce a directivity enhancement effect, and then pass through these microstructures of the optical film to maintain defect concealment ability. In this way, the optical film promotes the concentrated emission of light rays while maintaining defect concealment ability, thereby improving light concentration at the light emission viewing angle of the backlight module and brightness at the front viewing angle. Brief explanation of the drawing
[0018] To more fully understand the embodiments and their advantages, they are described as follows with reference to the drawings. FIG. 1a is a schematic plan view of a backlight module according to one embodiment of the present invention. Figure 1b is a schematic cross-sectional view drawn along the cross-sectional plane along line 1B-1B of Figure 1a. Figure 1c is a partial planar schematic of the optical film of Figure 1b. FIG. 1d is a partial planar schematic diagram of an optical film according to another embodiment of the present invention. FIG. 2a is a schematic plan view of a backlight module according to another embodiment of the present invention. Figure 2b is a schematic cross-sectional view drawn along the cross-sectional plane along the line 2B-2B of Figure 2a. FIG. 2c is a perspective schematic of the backlight module of FIG. 2b. Figures 2d and 2e are planar schematic diagrams of a portion of the prism sheet of Figure 2b. FIGS. 3a and FIGS. 3b are schematic plan views of a plurality of prism sheets according to another embodiment of the present invention. FIGS. 4a and FIGS. 4b are spatial luminance distribution diagrams of a backlight module according to a comparative example and a backlight module shown in FIG. 1b, respectively. Figure 5a is a spatial luminance distribution of a backlight module according to a comparative example. FIGS. 5b to 5e are spatial luminance distribution diagrams of a backlight module according to various embodiments of the present invention. FIG. 6 is a schematic cross-sectional view of a backlight module according to another embodiment of the present invention. FIG. 7 is a side schematic diagram of a display device according to one embodiment of the present invention. Specific details for implementing the invention
[0019] In the following description, to clearly present the technical features of the present invention, the dimensions (e.g., length, width, thickness, and depth) of the components (e.g., layers, films, substrates, regions, etc.) in the drawings have been enlarged by various proportions, and the number of some components has been reduced. Accordingly, the description and interpretation of the following embodiments are not limited to the number, size, and shape of the components shown in the drawings, but must encompass all variations in size, shape, and both resulting from actual manufacturing processes and / or tolerances. For example, flat surfaces depicted in the drawings may have rough and / or non-linear features, and corners depicted in the drawings may be rounded. Therefore, the components depicted in the drawings of the present invention are primarily for illustrative purposes and are not intended to accurately depict the actual shapes of the components, nor are they intended to limit the scope of protection of the claims of the present invention.
[0020] Furthermore, terms such as “approximately,” “roughly,” or “substantially” appearing in the content of the present invention include not only explicitly stated numerical values and numerical ranges, but also acceptable deviation ranges that are understandable to those skilled in the art, which may be determined by errors occurring during measurement, such errors may arise, for example, due to limitations of the measurement system or process conditions. Additionally, “approximately” may indicate within one or more standard deviations of the above numerical values, such as within ±30%, ±20%, ±10%, or ±5%. Terms such as “approximately,” “roughly,” or “substantially” appearing in the present invention may select an acceptable deviation range or standard deviation according to optical properties, etching properties, mechanical properties, or other properties, but a single standard deviation does not apply to all properties, such as optical properties, etching properties, mechanical properties, or other properties.
[0021] FIG. 1a is a schematic plan view of a backlight module according to an embodiment of the present invention, and FIG. 1b is a schematic cross-sectional view drawn along the cross-sectional plane along line 1B-1B of FIG. 1a. Referring to FIG. 1a and FIG. 1b, the backlight module (100) includes an optical film (110), a light guide plate (130), and a light source (190). The light guide plate (130) has an incoming light surface (131) and an outgoing light surface (132), and the outgoing light surface (132) has a normal (N1) and can be connected to one side of the incoming light surface (131). The light source (190) is installed adjacent to the incoming light surface (131) and can emit a light ray (L1) toward the incoming light surface (131). The optical film (110) is installed facing the light-emitting surface (132) and includes a plurality of parallel prisms (111) and a plurality of microstructures (112).
[0022] The extension direction (E1) of each prism (111) is perpendicular to the normal (N1), and each prism (111) faces the light-emitting surface (132) of the light guide plate (130). Each microstructure (112) is located on a surface of the optical film (110) that is away from the light guide plate (130), and each microstructure (112) is a conical structure having a plurality of facets (112s), and these prisms (111) are located between these microstructures (112) and the light-emitting surface (132). Additionally, in FIG. 1a, the microstructures (112) are omitted to clearly show the direction of the prisms (111), and in FIG. 1a, thick dotted lines represent the wave curve between two adjacent prisms (111), and thin dotted lines represent the wave peaks of each prism (111).
[0023] The light guide plate (130) may further be provided with a bottom surface (133), and the light-emitting surface (132) and the bottom surface (133) may be opposite to each other, and the bottom surface (133) and the light-emitting surface (132) may be opposite sides of the light guide plate (130), as shown in FIG. 1B. When a light source (190) emits a light ray (L1) toward the light-receiving surface (131), the light ray (L1) enters the light guide plate (130) from the light-receiving surface (131), and a portion of the light ray (L1) may be incident from the light-receiving surface (131) to the bottom surface (133). The bottom surface (133) may reflect a portion of the light ray (L1). For example, the bottom surface (133) can continuously reflect light rays within the light guide plate (130) through Total Internal Reflection (TIR) to transmit the light rays to the rear of the light guide plate (130). Another portion of the light rays (L1) has its reflection angle changed by the total internal reflection being destroyed by a microstructure placed on the bottom surface (133), and exits the light guide plate (130) from the light-emitting surface (132) and is incident on the prism (111) of the optical film (110). By using such a prism (111), the directivity can be improved by promoting the concentrated emission of the light rays (L1).
[0024] Subsequently, the light ray (L1) enters the optical film (110) from the prism (111) and exits the optical film (110) from the microstructure (112) to maintain defect concealment. The defect concealment effect is mainly achieved because the microstructure (112) is provided with a plurality of facets (112s). By deflecting the light ray (L1) through the plurality of facets (112s) and guiding it in multiple light-emitting directions, the defect concealment effect can be achieved by preventing the light energy from being excessively concentrated directly above the microstructure (112). Conventional grid point microstructures or diffuse particles scatter light rays in uncertain directions, so the defect concealment direction cannot be effectively controlled.
[0025] When a light ray (L1) passes sequentially through a light guide plate (130) and an optical film (110) and exits the backlight module (100), the prism (111) and the microstructure (112) refract the light ray (L1) so that the exit angle of the light ray (L1) from the optical film (110) is not the same as the exit angle of the light ray (L1) from the light guide plate (130), and the optical film (110) can also promote the light ray (L1) to be deflected and exited in the direction of the normal (N1), thereby improving the light concentration at the light exit viewing angle of the backlight module and the brightness at the front viewing angle.
[0026] In the case of a backlight module of the prior art, for example, a structure of two diffusion sheets and two prism sheets is used, so the light emission viewing angle is tilted about 60 degrees with respect to the vertical direction of the light emission surface (132) of the light guide plate (130) and lacks directivity, so the total light emission energy is not limited to a specific angle, and thus the anti-peeping effect is reduced. When the diffusion sheets of the prior art are replaced with an optical film (110), directivity can be improved and the total light emission energy is further concentrated so that the light rays are more deflected in the vertical direction of the light emission surface (132) of the light guide plate (130), and the light emission viewing angle is about 40 to 50 degrees.
[0027] That is, this optical film (110) has high directivity and defect concealment retention characteristics, and the brightness at the frontal viewing angle is further improved, saving energy and increasing the range of flight, and can meet future trends in brightness improvement.
[0028] Additionally, the light source (190) comprises a plurality of light-emitting diodes (191) arranged along a straight line (SL1). Specifically, these light-emitting diodes (191) can be mounted on a strip-shaped circuit board to arrange them in a straight line, that is, along the straight line (SL1), and the light-emitting diodes (191) and the circuit board can be integrated into a single light bar, and the circuit board can be a Printed Circuit Board (PCB) or a Flexible Printed Circuit (FPC). Additionally, the extension direction (E1) of these prisms (111) of the optical film (110) can be parallel to the straight line (SL1), as shown in FIG. 1a.
[0029] FIG. 1c is a partial planar schematic of the optical film of FIG. 1b, and the optical film (110) shown in FIG. 1b can be drawn according to the cross-sectional plane along the cross-sectional line (CR1) of FIG. 1c. Referring to FIG. 1b and FIG. 1c, these microstructures (112) may be a plurality of adjacent pyramidal concave holes, and facets (112s) may be sidewalls of the pyramidal concave holes. For example, since each microstructure (112) may be a pyramidal concave hole, each microstructure (112) may have four facets (112s) (i.e., sidewalls), and the angle between two opposing facets (112s) may be about 90 degrees. Accordingly, these microstructures (112) may be regular pyramids symmetrical along both the X-axis and Y-axis directions, or asymmetric pyramids symmetrical along one of the X-axis and Y-axis directions and asymmetrical along the other, so that different degrees of light deflection occur in different directions, thereby effectively controlling the defect concealment effect in different directions. In addition, in another embodiment, these microstructures (112) may be a plurality of adjacent pyramid-shaped protrusions, and their shape may be pyramid-shaped, and the facets (112s) may be sides of the pyramid-shaped protrusions. Accordingly, the microstructures (112) may be protrusions or concave holes, and FIGS. 1b and FIGS. 1c are for illustrative purposes only and are not intended to limit the invention. In FIG. 1b and FIG. 1c, these microstructures (112) are arranged in a matrix along the length direction of one side of the optical film (110), and in another embodiment shown in FIG. 1d, these microstructures (112) of the optical film (110') of FIG. 1d may be arranged in an array obliquely with respect to the length of one side of the optical film (110).
[0030] FIG. 2a is a schematic plan view of a backlight module according to another embodiment of the present invention, and FIG. 2b is a schematic cross-sectional view drawn along the cross-sectional plane along line 2B-2B of FIG. 2a. Referring to FIG. 2a and FIG. 2b, the backlight module (200) according to the present embodiment is similar to the backlight module (100) according to the previously described embodiment. For example, the backlight module (200) also includes an optical film (110), a light guide plate (130), and a light source (190). The following description will focus on the differences between the backlight module (100) and the backlight module (200). The similarities between the backlight module (200) and the backlight module (100) will not be explained repeatedly.
[0031] In this embodiment, these light-emitting diodes (191) within the light source (190) are also arranged along a straight line (SL1). However, unlike the backlight module (200) of the above-described embodiment, these prisms (111) of the optical film (110) are extended along an extension direction (E2), and the extension direction (E2) is perpendicular to the straight line (SL1), as shown in FIG. 2a. Since the extension direction (E1) can be parallel to the straight line (SL1), the extension direction (E1) can be perpendicular to the extension direction (E2).
[0032] FIG. 2c is a perspective schematic diagram of the backlight module of FIG. 2b. Referring to FIG. 2b and FIG. 2c, the backlight module (200) further includes a plurality of prism sheets (221) and a diffusion sheet (222), and an optical film (110) is positioned between these prism sheets (221), the diffusion sheet (222), and the light-emitting surface (132). These prism sheets (221) may include a plurality of prism sheets. In the embodiment illustrated in FIG. 2b, the prism sheets (221) are prism sheets, and these prism sheets (221) are positioned between the diffusion sheet (222) and the optical film (110). Additionally, in FIG. 2a, the prism sheets (221), the diffusion sheet (222), and the microstructure (112) are omitted to clearly show the extension direction (E2) of these prisms (111) of the optical film (110).
[0033] FIGS. 2D and FIGS. 2E are planar schematic diagrams of the prism sheets (i.e., prism sheets (221)) of FIG. 2B, the prism sheet (221) shown in FIG. 2D is the prism sheet (221) located on the lower side in FIG. 2B, and the prism sheet (221) shown in FIG. 2E is the prism sheet (221) located on the upper side in FIG. 2B. Referring to FIGS. 2B through 2E, each prism sheet (221) (i.e., prism sheet) comprises a plurality of parallel prism strips (221s). In FIGS. 2D and 2E, thick lines indicate the trough between two adjacent prism strips (221s), and thin lines indicate the crest of each prism strip (221s).
[0034] In order for these prism sheets (221) to induce most of the light rays (L1) to be emitted in a direction parallel to the normal (N1), the extension direction of these prism strips (221s) of one of the prism sheets (221) is perpendicular to the extension direction of these prism strips (221s) of another prism sheet (221). In the embodiment illustrated in FIG. 2d and FIG. 2e, the prism strip (221s) of the upper prism sheet (221) extends along the extension direction (E2) (as illustrated in FIG. 2d), and the prism strip (221s) of the lower prism sheet (221) extends along the extension direction (E1) (as illustrated in FIG. 2e), so the extension direction (E2) of the prism strip (221s) of the upper prism sheet (221) is perpendicular to the extension direction (E1) of the prism strip (221s) of the lower prism sheet (221).
[0035] Since the extension direction (E1) is parallel to the straight line (SL1) and the extension direction (E2) is perpendicular to the straight line (SL1), the extension direction (E1) of the prism strip (221s) of the lower prism sheet (221) is parallel to the straight line (SL1), and the extension direction (E2) of the prism strip (221s) of the upper prism sheet (221) is perpendicular to the straight line (SL1). Accordingly, in this embodiment, the extension direction (E1) of these prism strips (221s) of one of the prism sheets (e.g., the lower prism sheet (221)) is parallel to the straight line (SL1), and the extension direction (E2) of these prism strips (221s) of the other prism sheet (e.g., the upper prism sheet (221)) is perpendicular to the straight line (SL1).
[0036] In the embodiment illustrated in FIG. 2d and FIG. 2e, particular attention should be paid to the fact that the extension directions (E1 and E2) of the prism strips (221s) of the two prism sheets (221) are parallel and perpendicular to the straight line (SL1), respectively. However, in other embodiments, the extension directions of each of these prism strips (221s) of these prism sheets (221) may not be parallel or perpendicular to the straight line (SL1).
[0037] Referring to FIGS. 3a and 3b, the prism sheets (321a and 321b) shown in FIGS. 3a and 3b are identical to the prism sheet (221) and both include a plurality of parallel prism strips (221s). The only difference from the prism sheet (221) is that the extension direction of the prism strips (221s) of the prism sheets (321a and 321b) is different from that of the prism sheet (221).
[0038] Specifically, the prism sheets (321a and 321b) illustrated in FIG. 3a and FIG. 3b can be applied to the backlight module (200) of FIG. 2b. For example, the prism sheet (321a) illustrated in FIG. 3a can replace the upper prism sheet (221) in FIG. 2b, and the prism sheet (321b) illustrated in FIG. 3b can replace the lower prism sheet (221) in FIG. 2b.
[0039] The above structure can be designed so that the extension direction of these prism strips of each prism sheet is neither parallel nor perpendicular to the arrangement direction of the light-emitting diodes (191) of the light source (190) by combining the effect of high directivity and defect concealment retention characteristics that occur when using the optical film (110) with the fact that the arrangement direction of the light-emitting diodes (191) of the light source (190) is parallel to the extension direction of these prism strips (221s) of each of these prism sheets (221) shown in FIG. 3a and 3b. For example, the prism sheet (221) shown in FIG. 3a extends along the extension direction (E31), and the prism sheet (221) shown in FIG. 3b extends along the extension direction (E32), and the extension directions (E31 and E32) are neither parallel nor perpendicular to the extension direction (E1), and the extension directions (E31) and (E32) are perpendicular to each other.
[0040] For example, the angle (A31) between the extension direction (E31) and the extension direction (E1) in FIG. 3a may be approximately 45 degrees, and the angle (A31) between the extension direction (E32) and the extension direction (E1) in FIG. 3b may be approximately 135 degrees. Thus, the extension directions (E31 and E32) are neither parallel nor perpendicular to the extension direction (E1), and the angle between the extension direction (E31) and the extension direction (E32) may be approximately 90 degrees, that is, the extension direction (E31) and the extension direction (E32) are perpendicular to each other. Accordingly, the direction of the light emission viewing angle can be adjusted to a vertical direction of the light emission surface (132) of the light guide plate (130), the light emission viewing angle is about 0 degrees, the brightness can be further improved, and the full width at half maximum (FWHM) of the light emission energy can be further concentrated, which helps to improve the anti-peeping effect.
[0041] It should be noted that the prism sheets (221) and diffusion sheets (222) illustrated in FIG. 2b can all be applied to the backlight module (100) of the aforementioned embodiment. Specifically, the backlight module (100) of FIG. 1b may further include the prism sheets (221) and diffusion sheets (222) of FIG. 2b. That is, the optical film (110) of FIG. 2b may be replaced with the optical film (110) of FIG. 1b. Thus, both the backlight module (100) and the backlight module (200) may include the prism sheets (221) and diffusion sheets (222).
[0042] FIGS. 4a and 4b are spatial luminance distributions of a backlight module according to a comparative example and a backlight module illustrated in FIG. 1b, respectively. The spatial luminance distributions (i.e., FIGS. 4a, 4b, and FIGS. 5a through 5e) are originally color drawings. In the present invention, the spatial luminance distribution is illustrated as a grayscale drawing, wherein the grayscale from bright to dark represents a trend of luminance change from low to high. That is, in the spatial luminance distribution of the present invention, the brighter the grayscale, the higher the luminance. Conversely, the darker the grayscale, the lower the luminance. Furthermore, the spatial luminance distributions illustrated in FIGS. 4a, 4b, and FIGS. 5a through 5e are all computer simulation drawings.
[0043] Referring to FIGS. 4a and 4b, FIG. 4a shows a backlight module according to a comparative example, which includes a light source, a light guide plate, and a diffusion sheet containing conventional scattering particles, but does not include any prism sheet. FIG. 4b shows a backlight module (100) illustrated in FIG. 1b, and the backlight module (100) illustrated in FIG. 4b does not include a prism sheet (221). Additionally, the light source and the light guide plate included in the backlight module according to the comparative example may be identical to the light source (190) and the light guide plate (130), respectively, as illustrated in FIG. 1b.
[0044] In FIGS. 4a and 4b, FIGS. 4a and 4b simulate observing the luminance distribution while looking down at the backlight module and the backlight module (100) according to the comparative example, and in FIGS. 4a and 4b, the vertical axis and the horizontal axis represent angles, and the center where the vertical axis and the horizontal axis intersect may represent the center axis of the light-emitting surface of the light guide plate (e.g., the light-emitting surface (132) of the light guide plate (130)).
[0045] Referring to FIGS. 1a, 1b, and 4b, taking the backlight module (100) as an example, the center where the vertical axis and the horizontal axis intersect in FIG. 4b is the same as the center axis (OB1) of the light-emitting surface (132) in FIG. 1a. The vertical axis angle in FIG. 4b is the same as the observation angle (SA1) shown in FIG. 1b. The observation angle (SA1) is the narrow angle between the center axis (OB1) and the observation direction (OD1), and the absolute value of the observation angle (SA1) is between 0 and 90 degrees. When the vertical axis angle in FIG. 4b is 0, it indicates that the narrow angle between the observation direction (OD1) and the center axis (OB1) is 0; that is, the vertical axis angle being 0 indicates the brightness of the backlight module (100) observed from the center axis (OB1) side.
[0046] When the vertical axis angle in FIG. 4b is a negative value, the observation direction (OD1) is oriented toward the light-input surface (131) of the light guide plate (130); that is, a negative vertical axis angle indicates the brightness of the backlight module (100) observed from one side of the light-output surface (132) adjacent to the light-input surface (131). Conversely, when the vertical axis angle in FIG. 4b is a positive value, the observation direction (OD1) deviates from the light-input surface (131) of the light guide plate (130); that is, a positive vertical axis angle indicates the brightness of the backlight module (100) observed from one side of the light-output surface (132) away from the light-input surface (131), which is the same as the observation angle (SA1) shown in FIG. 1b. Likewise, the change in brightness along the horizontal axis in FIG. 4b represents the brightness distribution between the left and right sides of the backlight module (100) in FIG. 1a.
[0047] The viewing angle of the backlight module according to the comparative example shown in FIG. 4a is approximately 61 degrees, and the viewing angle of the backlight module (100) shown in FIG. 4b is approximately 40 degrees, and the viewing angle refers to the angle of the light peak. In FIG. 4a, most of the area has a significantly bright grayscale, whereas in FIG. 4b, most of the area has a significantly dark grayscale, and only a specific small area has a relatively bright grayscale and its internal color produces the darkest grayscale. From this, it can be seen that using the optical film (110) results in a higher light directionality of the backlight module (100) than that of the backlight module according to the comparative example.
[0048] In addition, the Full Width at Half Maximum (FWHM) on the vertical axis of the backlight module according to the comparative example of FIG. 4a is approximately 69 degrees, and the Full Width at Half Maximum on the horizontal axis is approximately 40 degrees. The Full Width at Half Maximum on the vertical axis of the backlight module (100) of FIG. 4b is approximately 40 degrees, and the Full Width at Half Maximum on the horizontal axis is approximately 10 degrees. Therefore, since the Full Width at Half Maximum of the backlight module (100) of FIG. 4b is smaller than the Full Width at Half Maximum of the backlight module according to the comparative example of FIG. 4a, the light directivity of the backlight module (100) of FIG. 4b is higher than that of the backlight module according to the comparative example of FIG. 4a, that is, the backlight module (100) illustrated in FIG. 4b can concentrate light emission more.
[0049] FIG. 5a is a spatial luminance distribution of a backlight module according to a comparative example, and FIG. 5b to 5e are spatial luminance distributions of a backlight module according to various embodiments of the present invention. Since the definitions of the vertical axis and the horizontal axis in FIG. 5a to 5e are all the same as the definitions of the vertical axis and the horizontal axis in FIG. 4a and FIG. 4b, they are not explained repeatedly here.
[0050] Referring to FIGS. 5a and 5b, the backlight module according to the comparative example shown in FIG. 5a includes a light guide plate and a diffusion sheet, as well as two prism sheets, but does not include an optical film (110). FIG. 5b shows a backlight module (100) with an optical film (110), two prism sheets (i.e., prism sheets (221)) and a diffusion sheet (222) installed, and the installation of the two prism sheets is as shown in FIG. 2b, FIG. 2d, and FIG. 2e, respectively, that is, the extension direction of the prism strip of one of the prism sheets is parallel to the extension direction of the prism (111) of the optical film (110) (both extension directions (E1)), and the extension direction of the prism strip of the other prism sheet is perpendicular to the extension direction of the prism (111) (each extension direction (E1 and E2)).
[0051] These prism sheets (e.g., prism sheet (221)) can guide light rays so that most of the light rays of the backlight module can be emitted along the normal (e.g., the normal (N1) in FIG. 1b). Accordingly, the viewing angle of the backlight modules of FIG. 5a and FIG. 5b is approximately 0 degrees. In addition, the luminance half-width along the vertical and horizontal axes of the backlight module according to the comparative example of FIG. 5a is 45 degrees. The luminance half-width along the vertical axis of the backlight module of FIG. 5b is approximately 38 degrees, and the luminance half-width along the horizontal axis is approximately 31 degrees. From this, it can be seen that the backlight module of FIG. 5b can concentrate the emission of light rays more, has higher light directivity than the backlight module according to the comparative example of FIG. 5a, and can improve the luminance by approximately 15%. In this structure, by combining the arrangement of the microstructure (112) shown in FIG. 1d obliquely along the length of one side of the optical film (110) with the extension direction (E2) of the prisms (111) of the optical film (110) in FIG. 2a, the energy of the FWHM can be further concentrated and the brightness further improved compared to the embodiment in which the extension direction (E1) of the optical film (110) in FIG. 1a extends along the extension direction (E1).
[0052] FIG. 5c is a spatial luminance distribution diagram of a backlight module according to another embodiment of the present invention shown in FIG. 3a and FIG. 3b. Referring to FIG. 5c, FIG. 5c also shows a backlight module (100) in which an optical film (110), two prism sheets (i.e., prism sheets (221)) and a diffusion sheet (222) are installed. However, unlike FIG. 5b, in the backlight module shown in FIG. 5c, the installation of the two prism sheets is as shown in FIG. 3a and FIG. 3b, respectively, that is, the extension direction of the prism strips of the two prism sheets is neither parallel nor perpendicular to the extension direction (E1) of the prism (111) of the optical film (110), and as shown in FIG. 3a and FIG. 3b, the direction of the prism strip of one of the prism sheets is 45 degrees, and the direction of the prism strip of the other prism sheet is 135 degrees.
[0053] In the embodiment illustrated in FIG. 5c, these prism sheets (e.g., prism sheet (221)) can induce light rays to be emitted along the normal (e.g., normal (N1) in FIG. 1b), so the viewing angle of the backlight module in FIG. 5c is about 0 degrees. Additionally, the luminance half-width along the vertical axis of the backlight module in FIG. 5c is about 34 degrees, and the luminance half-width along the horizontal axis is about 30 degrees. Therefore, compared to the backlight module according to the comparative example in FIG. 5a, the backlight module in FIG. 5c can concentrate light rays more, resulting in excellent light directivity and an improvement in luminance of about 20%.
[0054] FIGS. 5d and FIGS. 5e are spatial luminance distribution diagrams of a backlight module according to another embodiment of the present invention, FIGS. 5d and FIGS. 5e both represent the backlight module (200) shown in FIGS. 2a and FIGS. 2b, that is, the prisms (111) of the optical film (110) are extended along the extension direction (E2). However, the backlight module (200) shown in FIG. 5d has an optical film (110) installed but does not include a prism sheet (221) and a diffusion sheet (222), FIG. 5e represents a complete backlight module (200), wherein the orientation of the prism strip of one prism sheet is 0 degrees and the orientation of the prism strip of the other prism sheet is 90 degrees, as shown in FIG. 2a. The viewing angle of the backlight module (200) in FIG. 5d is approximately 52 degrees, the luminance half-width along the vertical axis is approximately 24 degrees, and the luminance half-width along the horizontal axis is approximately 20 degrees. Therefore, compared to the backlight module according to the comparative example in FIG. 4a, the backlight module (200) shown in FIG. 5d has excellent light directivity because it does not have a prism sheet (i.e., a prism sheet (221)) and a diffusion sheet (222), and generates a spectral effect so that the viewing angles on the left and right (bright color areas on both sides, dark areas within the bright color areas, and white areas) can all have sufficient luminance.
[0055] In FIG. 5e, by guiding light rays through these prism sheets (221) (i.e., prism sheets), the viewing angle of the backlight module (200) (including the prism sheets (221) and the diffusion sheet (222)) is about 0 degrees. Additionally, the luminance half-width along the vertical axis of the backlight module (200) shown in FIG. 5e is about 34 degrees, and the luminance half-width along the horizontal axis is about 27 degrees. Compared to the comparative example of FIG. 5a, the backlight module (200) of FIG. 5e has excellent light directivity, and can concentrate the spectral effect of FIG. 5d on the front viewing angle (the bright area in the center, the dark area within the bright area, and the white area) and improve the luminance by about 20%.
[0056] FIG. 6 is a schematic cross-sectional view of a backlight module according to another embodiment of the present invention. Referring to FIG. 6, the backlight module (600) according to this embodiment is similar to the backlight module (100) according to the previously described embodiment, and the difference between the backlight module (600) and the backlight module (100) is that the light guide plate (630) included in the backlight module (600) is different from the light guide plate (130) of the previously described embodiment. Below, the differences between the backlight module (600) and the backlight module (100) will be explained in detail, and identical features between the two will not be explained repeatedly.
[0057] Specifically, the light guide plate (630) has a bottom surface (633) and a plurality of light guide structures (639) formed on the bottom surface (633), and each light guide structure (639) has a large light surface (639a) and a small light surface (639b) connected to each other, and the large light surface (639a) faces the direction of travel of the light ray (L1) of the light source (190). A first angle (A61) is formed between the large light surface (639a) and the bottom surface (633), and a second angle (A62) is formed between the small light surface (639b) and the bottom surface (633), and both the first angle (A61) and the second angle (A62) are acute angles, and the first angle (A61) is smaller than the second angle (A62), as shown in FIG. 6.
[0058] When a light source (190) emits a light ray (L1) toward the light receiving surface (631) of a light guide plate (630), the light ray (L1) enters the light guide plate (630) from the light receiving surface (631), and a portion of the light ray (L1) may be incident on the light guide structure (639), for example, on the light-reducing surface (639a). To facilitate the light ray (L1) being emitted from the light-reducing surface (632) of the light guide plate (630), the light ray (L1) may be reflected by the light guide structure (639) (for example, the light-reducing surface (639a)). Through this design, the area of the large light surface (639a) is expanded and the area of the non-large light surface (639b) is reduced in order to further increase the probability that the large light surface (639a) reflects light rays, thereby supplying light rays from the light-emitting surface (632) of the light guide plate (630) for use by the optical film (110), which helps to improve the directional effect.
[0059] The backlight module (600) may further include a reflective sheet (680), the reflective sheet (680) is positioned below the light guide plate (630) and faces the bottom surface (633), and the light guide plate (630) is positioned between the reflective sheet (680) and the optical film (110). When a light ray (L1) is incident on the light guide structure (639), the light guide structure (639) can not only reflect the light ray (L1) but also refract the light ray (L1), as shown in FIG. 6. When the light guide structure (639) refracts the light ray (L1), the light ray (L1) can be incident on the reflective sheet (680). The reflective sheet (680) can reflect the light ray (L1) so that the light ray (L1) can be re-entered into the light guide plate (630), thereby allowing more light rays (L1) to be emitted from the light-emitting surface (632). This helps improve the brightness of the backlight module (600).
[0060] It should be noted that the backlight module (600) of FIG. 6 may further include a plurality of prism sheets (221) and a diffusion sheet (222) (as shown in FIG. 2b) or a plurality of prism sheets (321a and 321b) (as shown in FIG. 3a and FIG. 3b). That is, in the backlight module (200) shown in FIG. 2b, the light guide plate (130) may be replaced with the light guide plate (630) shown in FIG. 6. Also, the optical film (110) of FIG. 6 may also be replaced with the optical film (110) of FIG. 2b. That is, in FIG. 6, these prisms (111) of the optical film (110) may be extended along the extension direction (E1) or the extension direction (E2).
[0061] FIG. 7 is a side schematic diagram of a display device according to an embodiment of the present invention. Referring to FIG. 7, the display device (700) includes a backlight module (710) and a display panel (720), and the display panel (720) is installed opposite the backlight module (710) and positioned above the light-emitting surface of the backlight module (710) so that the backlight module (710) can emit light rays toward the display panel (720).
[0062] The backlight module (710) may be a backlight module (100, 200, or 600) according to the above-described embodiment, or any combination of these backlight modules (100, 200, and 600), for example, a backlight module (100) including a plurality of prism sheets (221) and diffusion sheets (222). Accordingly, the backlight module (710) includes an optical film (110). The display panel (720) may be a transmissive display panel such as a liquid crystal display panel. Since the optical film (110) can improve the light directionality of the backlight module (710) by promoting the concentrated emission of light rays (L1) while maintaining the ability to conceal defects, the backlight module (710) can uniformly emit high-brightness light rays to improve light concentration at the light emission viewing angle and brightness at the front viewing angle, and at the same time, it also possesses a defect concealment effect to improve the brightness and uniformity of the display panel (720).
[0063] Although embodiments of the present invention have been described above, this is not intended to limit the invention. Since those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, the scope of protection of the present invention should be based on the scope of protection defined by the appended claims. Explanation of the symbols
[0064] 100, 200, 600, 710: Backlight module 110, 110': Optical film 111: Prism 112: Microstructure 112s: Facet 130, 630: Light guide plate 131, 631: Ipgwang-myeon 132, 632: Ejection surface 133, 633: Bottom surface 190: Light source 191: Light Emitting Diode 221, 321a, 321b: Prism sheets 221s: Prism Strip 222: Diffusion Sheet 639: Light guide structure 639a: Daegwang-myeon 639b: Non-large surface 680: Reflective sheet 700: Display device 720: Display panel A31: Bectus A61: 1st angle A62: Second angle CR1: Section line E1, E2, E31, E32: Extension direction L1: Ray N1: Normal OB1: Central axis OD1: Direction of observation SA1: Observation angle SL1: Straight line.
Claims
Claim 1 An optical film, wherein a light ray from a light source is incident on one surface of the optical film and emitted from the other surface, the optical film comprises a plurality of parallel prisms and a plurality of microstructures, wherein the plurality of prisms are installed on one surface of the optical film and the microstructures are located on the other surface of the optical film, and each of the microstructures is a conical structure having a plurality of facets and is arranged in an array. Claim 2 An optical film according to claim 1, wherein the light source comprises a plurality of light-emitting diodes installed along the arrangement direction, and the extension direction of the prism of the optical film is oriented along the arrangement direction of the plurality of light-emitting diodes. Claim 3 An optical film according to claim 1 or 2, wherein a plurality of the microstructures are arranged obliquely with respect to the length of any one side of the optical film. Claim 4 A backlight module comprising: a light guide plate having a light input surface and a light output surface corresponding to the light input surface, wherein a light source is installed adjacent to the light input surface; an optical film according to any one of claims 1 to 3; and a plurality of prisms, wherein each of the prisms faces the light output surface of the light guide plate, and the optical film is positioned between the prism and the light output surface of the light guide plate. Claim 5 A display device comprising: a backlight module according to claim 4; and a display panel installed opposite to the backlight module.