Front light module and reflective display screen

Abstract

The front light module comprises a light guide plate, lattice points and a light source, the light guide plate comprises a first surface, a second surface and a third surface facing the light source, the first surface and the second surface are oppositely arranged, the second surface is a light emitting surface, the lattice points are arranged on the first surface, and an ink layer is arranged on the light incident side of the light guide plate. According to the front light module, a large amount of light is emitted from the light-emitting face in the collimation direction by designing the lattice point morphology, meanwhile, the proportion of the light emitted from the lattice points is reduced by printing ink on the light-in side, and therefore the reflective display screen carrying the front light module has the characteristics of high brightness and high contrast ratio. The invention further discloses a reflective display screen.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical elements. Specifically, the present invention relates to a front light module and a reflective display screen. Background Art

[0002] Reflective display technology mainly realizes display by reflecting ambient light, enabling users to have a viewing experience similar to traditional paper. As a new type of green and healthy display technology, reflective display has been increasingly applied. However, reflective display technology is extremely dependent on external light sources. When in an environment with weak external light sources, a front light module is required to provide supplementary light sources.

[0003] The front light module mainly includes a light source and a light guide plate, and the light guide dots on the light guide plate play an important role in breaking total internal reflection of light and changing the propagation direction to make it exit from the light exit surface. The morphology of the light guide dots determines the light exit direction of the light. When most of the light exits in a collimated direction, the brightness of the reflective display device will be greatly improved. In addition, since the light guide plate is arranged in front of the display panel, some light will directly exit from the dots without being reflected by the display panel, affecting the contrast of the reflective display device.

[0004] For example, the patent document with the publication number CN115933253A discloses a front light module, which includes: a light guide plate having an incident light surface, a first surface, and a second surface, the first surface and the second surface connecting the incident light surface and being opposite to each other; a light source disposed adjacent to the incident light surface; a plurality of first microstructures disposed at intervals and configured on the first surface; a light-transmitting cover plate; and a dielectric layer formed between the light guide plate and the light-transmitting cover plate and covering the surface of the first microstructures. The technical solution disclosed in this patent document also cannot solve the above-mentioned technical problems. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. For this purpose, the present invention provides a front light module, aiming to improve the display effect of a reflective display screen equipped with this front light module.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a front light module, including a light guide plate, dots, and a light source. The light guide plate includes a first surface, a second surface, and a third surface facing the light source. The first surface and the second surface are relatively arranged, the second surface is the light exit surface, the dots are arranged on the first surface, and an ink layer is arranged on the light incident side of the light guide plate.

[0007] The dots are concave dots or convex dots.

[0008] The shape of the dots is a pyramid, a frustum of a pyramid, a cone, or a frustum of a cone.

[0009] The ink layer is disposed on the first surface and the second surface.

[0010] The ink layer is a black ink, and the transmittance of the ink layer is less than 5%.

[0011] The thickness of the ink layer is 3 - 20 um.

[0012] The width D of the ink layer needs to satisfy where T is the thickness of the light guide plate, and β is the total reflection angle of the light guide plate.

[0013] The light guide plate is made of plastic or glass.

[0014] The refractive index of the light guide plate is 1.4 - 2.0.

[0015] The present invention also provides a reflective display screen, including the front light module described above.

[0016] In the front light module of the present invention, by designing the dot morphology, a large amount of light exits from the light exit surface in a collimated direction, and at the same time, ink is printed on the light incident side to reduce the proportion of light exiting from the dots, so that the reflective display screen equipped with this front light module has the characteristics of high brightness and high contrast. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] This specification includes the following drawings, and the shown contents are respectively:

[0018] Figure 1 is a schematic structural diagram of the front light module of the present invention;

[0019] Figure 2 is Schematic diagram of light source emitting light ;

[0020] Figure 3 is a top view of the front light module of the present invention;

[0021] Figure 4 is a schematic diagram of parameter definition;

[0022] Figure 5 is a schematic diagram of different incident angles;

[0023] In the figure, the marks are:

[0024] 10. Light guide plate; 101. First surface; 102. Second surface; 103. Third surface; 11. Dots; 12. Light source; 13. Ink layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The following will, with reference to the accompanying drawings, further elaborate on the specific implementation manners of the present invention through the description of embodiments, aiming to help those skilled in the art have a more complete, accurate, and in-depth understanding of the concept and technical solutions of the present invention and facilitate its implementation.

[0026] It should be noted that in the following embodiments, the so-called "first", "second", and "third" do not represent an absolute distinction relationship in terms of structure and / or function, nor do they represent the execution order, but are only for the convenience of description.

[0027] As Figure 1 shown, the present invention provides a front light module, including a light guide plate 10, light dots 11, and a light source 12. The light guide plate 10 includes a first surface 101, a second surface 102, and a third surface 103 facing the light source 12. The first surface 101 and the second surface 102 are located on opposite sides of the light guide plate 10. The second surface 102 is the light-emitting surface, and the third surface 103 is the light-incident surface. The first surface 101 is the top surface of the light guide plate 10, and the second surface 102 is the bottom surface of the light guide plate 10, that is, the second surface 102 and the first surface 101 are respectively located on the upper and lower sides of the light guide plate 10. There are two third surfaces 103. The first surface 101 and the second surface 102 are located between the two third surfaces 103, and the third surfaces 103 are located on the left and right sides of the light guide plate 10. An ink layer 13 is provided on the light-incident side of the light guide plate 10. The ink layer 13 is used to filter out the light whose incident angle α into the light guide plate satisfies the set condition, and the set condition is 90° - β < α < 2β, where β is the total reflection angle of the light guide plate.

[0028] As Figure 1 shown, the light source 12 is arranged outside the third surface 103 of the light guide plate 10. There is a certain distance between the light source 12 and the third surface 103. The closer the light source 12 is to the third surface 103, the higher the light incident efficiency.

[0029] Preferably, the light guide plate 10 can be made of, including but not limited to, plastic or glass, and the refractive index of the light guide plate 10 is 1.4 - 2.0. The function of the light guide plate 10 is to regulate the light incident from the point light sources 12 on both sides and change the propagation direction so that it exits from the second surface 102.

[0030] The light source 12 is a light-emitting diode (LED). The LED light source is a Lambert source. The light guide plate can be single-sided light-incident or double-sided light-incident, that is, whether to set the light source 12 on the two side surfaces of the light guide plate can be determined according to actual needs, and the number of the light sources 12 can be set by itself and can be arranged at equal intervals.

[0031] Preferably, the ink layer is a black ink, the transmittance of the ink layer is less than 5%, and the thickness of the ink layer is 3-20 um. When the light guide plate uses double-sided light input, ink layers are printed on both sides of the first surface 101 and the second surface 102, as Figure 3 shown. When the light guide plate uses single-sided light input, ink layers are printed on the light input sides of the first surface 101 and the second surface 102.

[0032] As Figure 1 shown, the dot 11 can be a convex dot or a concave dot, and the dot 11 is surrounded by a top surface, a bottom surface and a side surface according to its shape. The angle between the top surface and the side surface (or the angle between the bottom surface and the side surface) of the dot 11 is the light incident angle θ, and the light incident angle of the dot satisfies β < θ < 45°, where β is the total reflection angle. The shape of the dot 11 includes but is not limited to a pyramid, a prism, a cone, a frustum of a cone, etc. The arrangement density of the dots 11 gradually increases as the distance between the dots 11 and the light source 12 increases.

[0033] The angle between the top surface and the side surface (or the angle between the bottom surface and the side surface) of the dot is the light incident angle θ, and the size of the light incident angle θ will affect the propagation direction of the light. As Figure 4 shown, assuming the refractive index of air is n 1 , and the refractive index of the light guide plate is n 2 , according to Snell's law. When α 1 = 90°, the total reflection angle β at this time can be calculated as β = arcsinn 1 / n 2 , since the light incident angle α 1 of the light source satisfies 0° < α 1 < 90°, it can be obtained that 0° < α 2 < β, then the incident angles α of all the light rays after the light rays of the light source enter the light guide plate satisfy 90° - β < α < 90°. When a light ray with an incident angle of α is reflected by a dot with a light incident angle of θ, the incident angle will become α - 2θ. If α - 2θ = 0°, that is, the reflected light ray is just collimated, at this time, the light rays with an incident angle less than α and the light rays with an incident angle greater than α will deviate from the collimated direction after being reflected by the dot, as Figure 5 shown in the following three cases.

[0034] In order to ensure that the light rays are reflected by the dots and then exit from the lower surface without total internal reflection occurring again, it is necessary to satisfy -β < α - 2θ < β. According to 90° - β < α < 90°, it can be obtained that 45° - β / 2 < θ < 45°. At this time, all the light rays can exit from the lower surface after being reflected by the dots once, so as to make full use of the light energy. In addition, when the light rays hit the dots, if the incident angle α - θ is less than the total reflection angle β, most of the light rays will refract out of the dots, resulting in a decrease in the contrast of the light guide plate. Therefore, the incident angle α - θ needs to be greater than β, that is, α > θ + β.

[0035] In order to make the light beam exit from the second surface downward in a collimated direction without allowing the light to exit from the dot, the following conditions must be met:

[0036]

[0037] When the incident light angle is β < θ < 45°, some light rays with the incident angle 2β < α < 90° will exit from the second surface in an approximately collimated direction, while a large amount of light rays with the incident angle 90° - β < α < 2β will exit from the dot.

[0038] In order to avoid a large amount of light rays exiting from the dot, black ink is printed on the light incident side of the light guide plate. As Figure 4 shown, all the incident angles α of the light rays entering the light guide plate from the light source can be represented by where T is the thickness of the light guide plate and d is the horizontal distance between the position where the light ray reaches the first surface and the light source. According to this formula, when the incident angle of the light ray is 90° - β < α < 2β, then In the present invention, the ink layer filters out the light rays with the incident angle 90° - β < α < 2β entering the light guide plate. Therefore, the width D of the ink layer needs to satisfy When the light rays with the incident angle 90° - β < α < 2β contact the ink layer, they will be absorbed or scattered by the ink layer, while some light rays with the incident angle 2β < α < 90° will exit from the second surface in an approximately collimated direction, achieving high brightness and high contrast at the same time. Of course, the width of the ink can be adjusted according to actual requirements in the present invention.

[0039] For the front light module with the above structure, by designing the incident light angle of the dot on the light guide plate, the light rays can exit from the light exit surface in a collimated direction to the greatest extent. At the same time, printing ink on the light incident side of the light guide plate reduces the proportion of light rays exiting from the dot, so that the reflective display device equipped with this front light module has the characteristics of high brightness and high contrast, effectively improving the display effect and increasing the product competitiveness.

[0040] Embodiment 1

[0041] In this embodiment, the light source is arranged on one side of the light guide plate. The light source faces the third surface 103 of the light guide plate. An ink layer 13 is provided at one end of the first surface 101 and the second surface 102. This end of the first surface 101 and the second surface 102 is the end close to the third surface 103. The dots on the first surface 101 are located between the ink layer 13 and the other end of the first surface 101.

[0042] Embodiment 2

[0043] In this embodiment, the light sources are arranged on both sides of the light guide plate, the light guide plate is located between the two light sources, and the two light sources respectively face two third surfaces 103 at both ends of the light guide plate. Ink layers 13 are provided at both ends of the first surface 101 and the second surface 102. The ink layers 13 provided at both ends of the first surface 101 and the second surface 102 are respectively close to the two light sources, and the dot patterns on the first surface 101 are located between the two ink layers 13 provided on the first surface 101.

[0044] The present invention also provides a reflective display screen, which includes the front light module with the above structure. For the specific structure of this front light module, reference can be made to Figure 1 , which will not be elaborated here. Since the reflective display screen of the present invention includes the front light module in the above embodiment, it has all the advantages of the above front light module.

[0045] The present invention has been described exemplarily in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited by the above methods. As long as various non-substantive improvements are made by adopting the method concept and technical solution of the present invention; or without improvement, the above concept and technical solution of the present invention are directly applied to other occasions, they are all within the protection scope of the present invention.

Claims

1. Front light module, comprising a light guide plate, light dots and a light source. The light guide plate includes a first surface, a second surface and a third surface facing the light source. The first surface and the second surface are oppositely arranged, and the second surface is the light-emitting surface. The light dots are arranged on the first surface, Characterized in that: An ink layer is provided on the light-incident side of the light guide plate.

2. The front light module according to claim 1, Characterized in that: The light dots are concave dots or convex dots.

3. The front light module according to claim 1, Characterized in that: The shape of the light dots is a pyramid, a frustum of a pyramid, a cone or a frustum of a cone.

4. The front light module according to any one of claims 1 to 3, Characterized in that: The ink layer is provided on the first surface and the second surface.

5. The front light module according to any one of claims 1 to 3, Characterized in that: The ink layer is black ink, and the transmittance of the ink layer is less than 5%.

6. The front light module according to any one of claims 1 to 3, Characterized in that: The thickness of the ink layer is 3 to 20 um.

7. The front light module according to any one of claims 1 to 3, Characterized in that: The width D of the ink layer needs to satisfy where T is the thickness of the light guide plate and β is the total reflection angle of the light guide plate.

8. The front light module according to any one of claims 1 to 3, Characterized in that: The light guide plate is made of plastic or glass.

9. The front light module according to any one of claims 1 to 8, Characterized in that: The refractive index of the light guide plate is 1.4 to 2.

0.

10. Reflective display screen, Characterized in that: Comprising the front light module according to any one of claims 1 to 9.

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