Optical panels, front light modules and displays

Abstract

The present invention relates to an optical plate, a front light module and a display. The display includes a front light module and a display panel spaced apart from the bottom side of the optical plate. The front light module includes an optical plate and a light-emitting unit for projecting light onto a light-incident surface. The optical plate is defined by a top side and a bottom side relative to each other, and has a light-incident surface located at one end of the optical plate, a light-emitting surface located on the top side of the optical plate and connected to the light-incident surface, a plurality of light-guiding structures provided on the light-emitting surface, and a bevel structure connecting the light-incident surface and the bottom side of the optical plate. The large-angle light projected by the light-emitting unit onto the optical plate is changed in angle by reflection from the bevel structure, and is reflected toward the bottom side of the optical plate at a better angle through the light-guiding structure. The light is then guided by reflection from the display panel and refraction from the light-guiding structure to emit light from the light-emitting surface at a smaller emission angle, thereby improving the utilization rate of the light and the brightness of the display.

Description

[0001] This application claims priority to Chinese patent application No. 202111501461.3 filed on December 9, 2021, entitled “Optical plate, front light module and display,” and all of its contents are incorporated herein by reference. Technical Field

[0002] The invention relates to an optical plate, in particular to an optical plate capable of improving light output brilliance, a front light module using the optical plate, and a display using the front light module. Background Art

[0003] Nowadays, in order to allow users to clearly see the content presented by the e-book reader in a dark or strong light environment, the e-book reader uses a front-lit display. The front-lit display includes a front-light module and a display panel. The front-light module includes an adjacent front-light plate and a light-emitting unit. The front-light plate has a light-emitting surface. The light emitted by the light-emitting unit will be incident on one end of the front-light plate and emitted to the display panel through refraction of the front-light plate. The display panel then emits the light from the light-emitting surface to the user's eyes. The front-lit display forms an image by reflecting light, thereby avoiding the interference of light in a strong light environment on the display image.

[0004] When the light-emitting unit emits light toward the front light panel, if the angle between the incident angle of the light and the optical axis is small, for example, less than 10 degrees, the light can be emitted from the light-emitting surface of the front light panel within a range of plus or minus 15 degrees from the normal viewing angle, allowing the light to smoothly enter the user's eyes. However, when the incident angle of the light is larger, for example, greater than 10 degrees, the light-emitting angle increases, and the light cannot be received by the user's eyes. In other words, the light-emitting angle of the light-emitting surface tends to diverge, so the light cannot be effectively utilized within the range of plus or minus 15 degrees from the normal viewing angle, resulting in lower light brightness of the front-lit display. Therefore, there is still room for improvement in conventional front-lit displays. Summary of the Invention

[0005] The main purpose of the present invention is to provide an optical plate, thereby improving the problem of low light output brightness of current front-lit displays.

[0006] To achieve the aforementioned objectives, the optical plate of the present invention is defined by a top side and a bottom side opposite to each other, and has:

[0007] A light incident surface, which is located at one end of the optical plate; a light emitting surface, which is located on the top side of the optical plate and connected to the light incident surface; a plurality of light-guiding structures, which are arranged on the light emitting surface of the optical plate, each light-guiding structure having a light-facing surface and a light-reflecting surface, the light-reflecting surface being connected to the side of the light-facing surface away from the light incident surface; and a bevel structure, which connects the light incident surface and the bottom side of the optical plate.

[0008] In order to achieve the aforementioned purpose, the present invention further provides a front light module, which includes: the optical plate as described above; and a light-emitting unit, which projects light onto the light incident surface.

[0009] In order to achieve the aforementioned objectives, the present invention further provides a display comprising: the front light module as described above; and a display panel spaced apart from the bottom side of the optical plate.

[0010] By means of the bevel structure of the optical plate of the present invention, large-angle light with an incident angle greater than 10 degrees can be effectively transmitted to the rear. After the large-angle light projected by the light-emitting unit to the optical plate is reflected by the bevel structure, the angle at which it is projected to the light-facing surface will change. As a result, the light-facing surface can reflect the light toward the bottom side of the optical plate at a better angle, and then guide the large-angle light from the light-emitting surface at a smaller angle through the reflection of the display panel and the guidance of the light-guiding structure of the light-emitting surface, thereby effectively improving the utilization rate of light with a larger incident angle, improving the light output brightness of the entire module at the required viewing angle, especially the light output brightness between plus or minus 15 degrees of the positive viewing angle of the light-emitting surface, and improving the light output brightness of the display of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] For a more complete understanding of the embodiments and their advantages, the following description is now made with reference to the accompanying drawings, in which:

[0012] Figure 1 is a partially enlarged plan view of a first preferred embodiment of the optical plate of the present invention;

[0013] Figure 2 is a partially enlarged plan view of a second preferred embodiment of the optical plate of the present invention;

[0014] Figure 3 is a partial plan view of the front light module of the present invention; and

[0015] Figure 4 Schematic diagram of the light path of the display of the present invention. DETAILED DESCRIPTION

[0016] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The accompanying drawings are mainly simplified schematic diagrams that only illustrate the basic structure of the present invention in a schematic manner. Therefore, only components related to the present invention are marked in the accompanying drawings, and the components shown are not drawn in terms of the number, shape, size ratio, etc. during implementation. The specifications and dimensions during actual implementation are actually a selective design, and the component layout may be more complex.

[0017] See also Figure 1 and Figure 2, which are various preferred embodiments of the optical plate 1 of the present invention, are defined with opposite top and bottom sides, and have a light incident surface 10 , a light emitting surface 20 , a plurality of light guide structures 30 and a slope structure 40 .

[0018] like Figure 1 and Figure 2 As shown, the light incident surface 10 is located at one end of the optical plate 1 ; the light emitting surface 20 is located on the top side of the optical plate 1 and connected to the light incident surface 10 , and light can enter the optical plate 1 from the light incident surface 10 and exit from the light emitting surface 20 .

[0019] like Figures 1 to 4 As shown, multiple light-guiding structures 30 are arranged on the light-emitting surface 20 of the optical plate 1, and have a light-facing surface 31 and a reflective light-facing surface 32. The reflective light-facing surface 32 is connected to the side of the light-facing surface 31 away from the light-incident surface 10. When light is projected toward the light-facing surface 31, it will be reflected by the light-facing surface 31 and emitted toward the bottom side of the optical plate 1. When light is emitted from the bottom side of the optical plate 1 toward the reflective light-facing surface 32, it will be refracted, thereby controlling the path of the light emitted from the light-emitting surface 20 of the optical plate 1.

[0020] like Figure 1 and Figure 2 As shown, the inclined surface structure 40 connects the light incident surface 10 and the bottom side of the optical plate 1 . The inclined surface structure 40 is used to control the path of the light incident on the optical plate 1 so that the light can be directed toward the light-facing surface 31 of the light guide structure 30 , thereby improving light utilization.

[0021] Furthermore, if Figure 1 As shown, in the first preferred embodiment of the optical plate 1 of the present invention, the bevel structure 40 includes a first bevel 41, and a first angle θ1 (also called bevel angle) is formed between the first bevel 41 and the bottom side of the optical plate 1. The first angle θ1 is an external angle, and the angle of the first angle θ1 is greater than 0 degree and less than or equal to 8 degrees, that is, 0°<θ1≤8°, wherein when light is projected onto the first bevel 41, it will be reflected.

[0022] A fourth angle θ4 (also known as the light-facing surface angle) is formed between the light-facing surface 31 of the multiple light-guiding structures 30 and the light-emitting surface 20. The fourth angle θ4 is an external angle. The angle of the fourth angle θ4 is greater than 42 degrees and less than or equal to 46 degrees, that is, 42°<θ4≤46°. The angle design of the fourth angle θ4 enables the light-facing surface 31 to receive the light reflected by the first inclined surface 41 and reflect the light toward the bottom side of the optical plate 1. In a preferred embodiment of the present invention, the degree of the fourth angle θ4 is half of the degree of the first angle θ1 plus 42 degrees, that is, θ4=0.5×θ1+42°. By designing that the fourth angle θ4 changes with the first angle θ1 of the first inclined surface 41, the light-facing surface 31 can reflect the light toward the bottom side of the optical plate 1 at a better angle, thereby improving the utilization rate of the light.

[0023] See also Figure 3 , is a preferred embodiment of the front light module of the present invention, which includes an optical plate 1 and a light-emitting unit 50 , and the light-emitting unit 50 projects light onto the light incident surface 10 .

[0024] The light emitting unit 50 has a central optical axis 51, and the central optical axis 51 corresponds to the thickness center from the top side to the bottom side of the optical plate 1. Figure 4 As shown, an incident angle α is formed between the light projected by the light-emitting unit 50 toward the optical plate 1 and the central optical axis 51. Among them, after the light with an incident angle α greater than 10 degrees (i.e., large-angle light) projected from the light-emitting unit 50 toward the optical plate 1 is reflected by the inclined surface structure 40, the angle at which the large-angle light is projected onto the light-facing surface 31 will be changed, so that the light-facing surface 31 can reflect the light toward the bottom side of the optical plate 1 at a better angle, thereby improving the utilization rate of the light. More preferably, by adjusting the first inclined surface 41, large-angle light with an incident angle α between 10 degrees and 35 degrees can be effectively emitted from the light-emitting surface 20 of the optical plate 1 within a range of plus or minus 15 degrees of the positive viewing angle, thereby improving the overall brightness of the light-emitting surface 20. The positive viewing angle is perpendicular to the light-emitting surface 20. The positive viewing angle of this embodiment can be referred to Figure 4 The two-point chain line in .

[0025] Furthermore, if Figure 3 As shown, the optical plate 1 defines a first direction D1 from the top to the bottom, and the front view is parallel to the first direction D1. The inclined structure 40 has a height h in the direction parallel to the first direction D1, and the height h is less than the thickness T from the top to the bottom of the optical plate 1. B Subtract the thickness T of the light emitting unit 50 parallel to the first direction D1 L Half of h<(T B -T L ) / 2, by designing the height h of the inclined surface structure 40, the light emitted by the light-emitting unit 50 is projected onto the light incident surface 10 of the optical plate 1, and will not be emitted prematurely from the position of the inclined surface structure 40, thereby avoiding the problem of uneven light emission caused by the utilization rate of light being affected and the position of the light emitting surface 20 being brighter near the light source.

[0026] In one embodiment, the thickness T of the light emitting unit 50 is L 0.3mm, choose thickness T B For an optical plate 1 with a thickness of 0.5 mm, the height h of the inclined surface structure 40 is less than 0.1 mm. If the first angle θ1 of the inclined surface structure 40 is no greater than 8 degrees, the length of the first inclined surface 41 is no less than 0.7185 mm. Furthermore, when the first angle θ1 is 1 degree, the length of the first inclined surface 41 is 5.80 mm.

[0027] In another embodiment, the thickness T of the light emitting unit 50 is L 0.3mm, choose thickness T BFor an optical plate 1 with a diameter of 0.6 mm, the height h of the inclined surface structure 40 is less than 0.15 mm. If the first angle θ1 of the inclined surface structure 40 is no greater than 8 degrees, the length of the first inclined surface 41 is no less than 1.0778 mm. Furthermore, when the first angle θ1 is 1 degree, the length of the first inclined surface 41 is 8.5948 mm. In other words, the length of the inclined surface structure 40 is on the millimeter scale, unlike the microstructures formed on the bottom surface of conventional optical plates to disrupt total internal reflection, which are on the micrometer or nanometer scale.

[0028] See also Figure 4 , which is a preferred embodiment of the display of the present invention, includes a front light module and a display panel 60, and the display panel 60 is spaced apart from the bottom side of the optical plate 1.

[0029] Therein, an emission angle β is formed between the light emitted from the light emitting surface 20 of the optical plate 1 and the first direction D1 .

[0030] When the light-emitting unit 50 projects light onto the light incident surface 10 of the optical plate 1, if the incident angle α of the light is small, that is, the incident angle α is between 0 degrees and 10 degrees, including the endpoint value, the light will be emitted toward the light-facing surface 31 of the multiple light-guiding structures 30, and be reflected toward the display panel 60 located on the bottom side of the optical plate 1. The display panel 60 reflects the light toward the light-emitting surface 20 of the optical plate 1, so that the light is refracted through the reflective light-facing surface 32 of the multiple light-guiding structures 30, and is emitted from the light-emitting surface 20 at a smaller exit angle β. Preferably, the exit angle β is between 0 degrees and 15 degrees, including the endpoint value.

[0031] When the incident angle α of the light is large, that is, the incident angle α is between 10 degrees and 35 degrees, and the light is deflected toward the bottom side of the optical plate 1, as shown in FIG. Figure 4As shown, taking the first preferred embodiment of the optical plate 1 applied to a display as an example, when the light is projected onto the first inclined surface 41 at an incident angle α, the reflection direction of the light is the incident direction of the light mirrored in the normal direction of the first inclined surface 41, so that the light reflected from the first inclined surface 41 forms a primary incident angle α' with the central optical axis 51. The secondary incident angle α' is the angle of the incident angle α minus twice the first included angle θ1, that is, α'=α-2×θ1. By reducing the angle of the incident angle α of the light to the angle of the secondary incident angle α' degrees, so that the light can be directed to the light-facing surface 31 of the light-guiding structure 30, and then through the angle design of the fourth angle θ4 of the light-facing surface 31 of the light-guiding structure 30, the light is projected onto the display panel 60 and reflected, and finally refracted through the reflective light-facing surface 32 of the light-guiding structure 30, so that it can be effectively utilized and emitted from the light-emitting surface 20 at a better exit angle β, thereby effectively improving the brightness of the display of the present invention and making the exit angle β of the light approach to the positive viewing angle, that is, the viewing angle of the light can converge toward the center, thereby improving the light extraction efficiency at the positive viewing angle.

[0032] Please refer to Table 1 for a comparison of the effects of the bevel structure 40 on the light output energy of the display. Assuming the same microstructure on the light output surface 20, the optical plate 1 with the bevel structure 40 can increase the light output energy of the display by 17% to 69%. This shows that the bevel structure 40 of the optical plate 1 can effectively enhance the brightness of the light output of the display of the present invention.

[0033] Table 1:

[0034]

[0035] Please refer to Table 2, which shows the effect of variations in the first angle θ1 of the first inclined surface 41 of the optical plate 1 and the fourth angle θ4 of the light-facing surface 31 of the plurality of light-guiding structures 30 on the luminance of the light emitted by the display of the present invention. Taking the luminance of a display without an inclined surface structure as a benchmark, and comparing different combinations of the first angle θ1 and the fourth angle θ4, Table 2 shows that, compared to a display with a luminance ratio of 100% when the first angle θ1 is 0 degrees (i.e., no inclined surface structure), or a display with a luminance ratio of 90% when the first angle θ1 is 9 degrees, the display with a luminance ratio of 112% to 116% can be more effectively improved when the first angle θ1 is greater than 0 degrees and less than or equal to 8 degrees.

[0036] Table 2:

[0037] The first angle θ1 The fourth angle θ4 Luminance ratio 0 42 100％ 1 42.5 112％ 3 43.5 116％ 8 46 112％ 9 46.5 90％

[0038] Furthermore, if Figure 2As shown, in a second preferred embodiment of the optical plate 1 of the present invention, the inclined surface structure 40 includes a second inclined surface 42 and a third inclined surface 43 connected to each other. The second inclined surface 42 is connected to the light incident surface 10, and the third inclined surface 43 is connected to the bottom side of the optical plate 1. A second angle θ2 is formed between the second inclined surface 42 and an imaginary plane parallel to the bottom side of the optical plate 1, and a third angle θ3 is formed between the third inclined surface 43 and the bottom side of the optical plate 1. Preferably, the second angle θ2 is greater than 3 degrees and less than or equal to 8 degrees, that is, 3°<θ2≤8°, and the third angle θ3 is greater than 0 degrees and less than or equal to 3 degrees, that is, 0°<θ3≤3°. Since the second inclined surface 42 is closer to the light incident surface 10 than the third inclined surface 43, the second inclined surface 42 is also called the front inclined surface 42, and the third inclined surface 43 is also called the rear inclined surface 43. The second angle θ2 is also called the front inclined surface angle, and the third angle θ3 is also called the rear inclined surface angle.

[0039] Among them, when the incident angle α of the light is between 22 degrees and 35 degrees, the light will be emitted to the second inclined surface 42 of the inclined surface structure 40; and when the incident angle α of the light is between 10 degrees and 22 degrees, the light will be emitted to the third inclined surface 43 of the inclined surface structure 40. By designing the second angle θ2 of the second inclined surface 42 and the third angle θ3 of the third inclined surface 43 to be different in angle, the inclined surface structure 40 can more accurately control the path of the light incident on the optical plate 1, so that light with a larger or smaller incident angle α can be precisely controlled and emitted to the light-facing surface 31 of the light guide structure 30 at a better angle, thereby improving the brightness of the light output.

[0040] Preferably, the ratio of the area of the second inclined surface 42 to the area of the third inclined surface 43 is greater than 0 and less than or equal to 1, that is, 0 A / A B ≤1, in the previous formula, A A is the area of the second inclined surface 42, A B is the area of the third inclined surface 43. Since the area of the second inclined surface 42 is the length L of the second inclined surface 42 A The area of the third inclined surface 43 is equal to the length L of the third inclined surface 43 multiplied by the width of the optical plate 1. B Multiply by the width of the optical plate 1, so that Figure 2 As shown, the length L of the second inclined surface 42 A The length L of the third inclined surface 43 B The ratio of is greater than 0 and less than or equal to 1, that is, 0 <L A / L B ​≤1, when the incident angle α of the light is large, the light will advance a shorter distance in the direction parallel to the central optical axis 51 in the optical plate 1 and will contact the inclined surface structure 40, and will fall into the section of the second inclined surface 42. When the incident angle α of the light is small, the light will advance a longer distance in the direction parallel to the central optical axis 51 in the optical plate 1 and will fall into the section of the third inclined surface 43. Therefore, the area of the second inclined surface 42 closer to the light-emitting unit 50 can be smaller than the area of the third inclined surface 43. Through the area ratio of the second inclined surface 42 to the third inclined surface 43, the inclined surface structure 40 can better cooperate with the light emitted by the light-emitting unit 50, thereby improving the utilization rate of the light. In other words, because light with an incident angle α greater than 22 degrees accounts for a smaller proportion and has a weaker intensity among the total light emitted by the light-emitting unit 50, and is only projected onto the second inclined surface 42 closer to the light-emitting unit 50, the area of the second inclined surface 42 can be smaller than the area of the third inclined surface 43. In other words, the third inclined surface 43 is used to adjust light with an incident angle α between 10 and 22 degrees, primarily to enhance the brightness of the emitted light. In summary, by designing the second angle θ2 greater than the third angle θ3 and the area of the third inclined surface 43 greater than the area of the second inclined surface 42, the inclined surface structure 40 can effectively adjust light with an incident angle α between 10 and 22 degrees using the third inclined surface 43, and effectively adjust light with an incident angle α between 22 and 35 degrees using the second inclined surface 42, thereby facilitating enhanced brightness of the display of the present invention.

[0041] In summary, when the light-emitting unit 50 of the front light module projects light onto the optical plate 1, light with a smaller incident angle α can be reflected through the light-guiding structure 30 of the optical plate 1 to the display panel 60 and then reflected, and is emitted from the light-emitting surface 20 of the optical plate 1 at a smaller exit angle β. When light with a larger incident angle α enters the optical plate 1, the incident angle α of the light can be reduced by reflection from the inclined structure 40, thereby allowing the light to also be emitted at a smaller exit angle β. In other words, the viewing angle of the light can converge toward the center to improve the light-emitting efficiency at the positive viewing angle, thereby effectively improving the utilization rate of the light and improving the light-emitting brightness of the display of the present invention.

[0042] The embodiments disclosed above are merely illustrative of the principles, features, and effectiveness of the present invention and are not intended to limit the scope of the present invention. Any skilled artisan may modify or alter the embodiments described above without departing from the spirit and scope of the present invention. Any equivalent changes or modifications made using the present invention are intended to fall within the scope of the appended claims.

[0043] Reference Signs List

[0044] 1: Optical plate

[0045] 10: Light incident surface

[0046] 20: Light-emitting surface

[0047] 30: Light guide structure

[0048] 31: Sun-facing side

[0049] 32: Reflective surface

[0050] 40: Slope structure

[0051] 41: First slope

[0052] 42: Second inclined surface (front inclined surface)

[0053] 43: Third inclined surface (rear inclined surface)

[0054] 50: Light-emitting unit

[0055] 51: Central optical axis

[0056] 60: Display panel

[0057] D1: First direction

[0058] h: height

[0059] L A : Length of the second inclined surface (front inclined surface)

[0060] L B : Length of the third inclined surface (rear inclined surface)

[0061] T B : Thickness from top to bottom of the optical plate

[0062] T L : The thickness of the light emitting unit parallel to the first direction

[0063] θ1: first angle (inclined angle)

[0064] θ2: Second angle (front bevel angle)

[0065] θ3: The third angle (the angle of the rear bevel)

[0066] θ4: The fourth angle (angle of the light-facing surface)

[0067] α: angle of incidence

[0068] α': secondary incident angle

[0069] β: exit angle.

Claims

1. An optical plate defining opposite top and bottom sides, the optical plate having: a light incident surface located at one end of the optical plate; a light emitting surface, located on the top side of the optical plate and connected to the light incident surface; A plurality of light-guiding structures are provided on the light-emitting surface of the optical plate, each of the light-guiding structures having a light-facing surface and a light-reflecting surface, wherein the light-reflecting surface is connected to a side of the light-facing surface away from the light-incident surface; as well as an inclined surface structure connecting the light incident surface and the bottom side of the optical plate; The inclined surface structure includes a first inclined surface, and an inclined surface angle is formed between the first inclined surface and the bottom side of the optical plate. The inclined surface angle satisfies the following formula: Wherein, θ1 is the angle of the inclined plane, A light-facing surface angle is formed between the light-facing surfaces of the plurality of light-guiding structures and the light-emitting surface, and the angle between the inclined surface and the light-facing surface satisfies the following formula: Wherein, θ4 is the angle of the light-facing surface.

2. The optical plate according to claim 1, wherein The inclined surface structure includes a front inclined surface and a rear inclined surface connected to each other, the front inclined surface is connected to the light incident surface, and the rear inclined surface is connected to the bottom side of the optical plate. A front inclined surface angle is formed between the front inclined surface and an imaginary plane parallel to the bottom side of the optical plate, and a rear inclined surface angle is formed between the rear inclined surface and the bottom side of the optical plate, wherein the front inclined surface angle satisfies the following formula: Wherein, θ2 is the front bevel angle; and The rear bevel angle satisfies the following formula: In the above formula, θ3 is the rear bevel angle.

3. The optical plate according to claim 2, wherein The ratio of the area of the front inclined surface to the area of the rear inclined surface satisfies the following formula: Among them, A A is the area of the front inclined surface, A B is the area of the rear inclined surface.

4. The optical plate according to any one of claims 1 to 3, wherein The angle of the light-facing surface satisfies the following formula: Wherein, θ4 is the angle of the light-facing surface.

5. A front light module comprising: The optical plate according to any one of claims 1 to 4; and A light-emitting unit projects light onto the light incident surface.

6. The front light module according to claim 5, wherein: The light emitting unit has a central optical axis corresponding to a thickness center from a top side to a bottom side of the optical plate.

7. The front light module according to claim 5, wherein: The inclined surface structure has a height in a first direction parallel to the top side to the bottom side of the optical plate, and the height satisfies the following formula: h < (T B - T L ) / 2 Wherein, h is the height, T B is the thickness from the top side to the bottom side of the optical plate, T L is the thickness of the light emitting unit parallel to the first direction.

8. A display comprising: The front light module according to any one of claims 5 to 7; and The display panel is spaced apart from the bottom side of the optical plate.

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