Front light module and electronic reader

Abstract

A front light module includes a point light source, a light guide strip, and a front light panel. The light guide strip includes a light-incident surface, a reflective surface connected to the light-incident surface, a light-emitting surface connected to the light-incident surface and opposite to the reflective surface, and a plurality of first microstructures disposed on the reflective surface, wherein the first microstructures are asymmetrical microstructures. The front light panel has a reference surface facing the light-emitting surface of the light guide strip, and a plurality of second microstructures disposed on the reference surface. The light from the point light source forms a line light source after passing through the light guide strip, and then forms a surface light source after passing through the front light panel. By using the first microstructures of the light guide strip in conjunction with the second microstructures of the front light panel, the light mixing distance can be reduced, the display area can be increased, and the requirement of narrow bezels can be met. The present invention also provides an e-reader including the front light module.

Description

[Technical Field]

[0001] This invention relates to an optical element, and more particularly to a front light module and an e-reader. [Previous Technology]

[0002] Currently, to ensure users can clearly see the content displayed on an e-reader in both dark and bright environments, a front-light display is used in the e-reader. The front-light display includes a front-light module and a display panel. The front-light module includes a front light plate and a light-emitting unit disposed adjacent to each other. The front light plate has a light-emitting surface. Light emitted by the light-emitting unit enters one end of the front light plate and is refracted through the front light plate before being emitted to the display panel. The display panel then projects the light from the light-emitting surface to the user's eyes. The front-light display achieves image formation by reflecting light, thus avoiding interference from light in bright environments.

[0003] With the development of technology, portable electronic products are increasingly demanding narrow bezel designs to increase display area. Furthermore, they must ensure the uniformity of the light-emitting surface while achieving a narrow bezel, avoiding hotspots at the edges of the light-emitting surface. Therefore, improving the internal structure of existing products to increase the display area and provide better light emission uniformity is an important R&D goal for relevant manufacturers. [Summary of the Invention]

[0004] Therefore, the object of the present invention is to provide a front light module that can reduce the light mixing distance to increase the display range and improve the light emission uniformity at the edge.

[0005] A front light module includes a point light source, a light guide strip for receiving light from the point light source, and a front light plate for receiving light emitted from the light guide strip. The light guide strip includes a light-incident surface, a reflective surface connected to the light-incident surface, a light-emitting surface connected to the light-incident surface and opposite to the reflective surface, and a plurality of first microstructures disposed on the reflective surface, each of the first microstructures being an asymmetrical microstructure. The front light plate has a reference surface facing the light-emitting surface of the light guide strip, and a plurality of second microstructures disposed on the reference surface.

[0006] Another technical means of the present invention is that each of the first microstructures of the light guide strip has a light-facing surface for reflecting light, and the angle θ between the light-facing surface and the reflective surface is 3 to 25 degrees, including the endpoint value.

[0007] Another technical means of the present invention is that the first microstructure of the light guide strip is an asymmetrical protrusion, and the distribution density of the first microstructure is more dense along the direction away from the point light source.

[0008] Another technical means of the present invention is that the cross-sectional shape of each of the second microstructures of the front light plate is an isosceles triangle.

[0009] Another technical means of the present invention is that the cross-sectional shape of each of the second microstructures of the front light plate is a non-isosceles triangle, and has a first working surface and a second working surface connected together. The first working surface is further away from the point light source than the second working surface. The first working surface and the reference surface have a first included angle θ1, and the second working surface and the reference surface have a second included angle θ2. The first included angle θ1 is smaller than the second included angle θ2.

[0010] Another technical means of the present invention is that the first included angle θ1 is 50 to 70 degrees and the second included angle θ2 is 70 to 90 degrees, including the endpoint values.

[0011] Another technical means of the present invention is that the light guide strip further includes a plurality of strip-shaped microstructures disposed on the light-emitting surface, the strip-shaped microstructures extending along a first direction.

[0012] Another technical means of the present invention is that the second microstructure extends along a second direction, and the first direction is perpendicular to the second direction.

[0013] Another technical means of the present invention is that each of the strip-shaped microstructures is an arc-shaped surface with a central angle of 70 to 100 degrees, including endpoint values.

[0014] Another technical means of the present invention is that the thickness of the light guide strip gradually decreases along the direction away from the point light source.

[0015] Another technical means of the present invention is that the front light module further includes at least one reflective element covering the light guide strip, the reflective element covering the area outside the light emitting surface of the light guide strip.

[0016] Another technical means of the present invention is that the front light module further includes at least one light-shielding member covering the light guide strip, the light-shielding member covering one end of the light guide strip adjacent to the point light source but not blocking the light-incident surface of the light guide strip.

[0017] Another technical means of the present invention is that the light-shielding member and the reflective member do not overlap.

[0018] Another object of the present invention is to provide an e-reader comprising a front light module as described above, and a display panel disposed on the front light module.

[0019] The advantage of this invention is that the light from the point light source forms a line light source after passing through the light guide strip, and then forms a surface light source after passing through the front light plate. By means of the first microstructure on the reflective surface of the light guide strip, in conjunction with the second microstructure of the front light plate, the light mixing distance at the light-incident edge of the front light plate can be reduced, the display range can be increased, and the requirements of narrow bezel e-readers can be met.

Implementation Method

[0021] The features and technical content of the related patent applications of this invention will be clearly presented in the following detailed description of the preferred embodiments with reference to the accompanying drawings. Before proceeding with the detailed description, it should be noted that similar elements are represented by the same numbers. The directional terms mentioned in the following embodiments, such as up, down, left, right, front, back, bottom, and top, are only for reference to the accompanying drawings. Therefore, the directional terms used are for illustrative purposes and not for limiting the invention.

[0022] Referring to Figures 1 and 2, a first preferred embodiment of the front light module of the present invention is shown, comprising a point light source 2, a light guide strip 3 for receiving light from the point light source 2, and a front light plate 4 for receiving light emitted from the light guide strip 3. As shown in Figure 2, the light guide strip 3 includes a light-incident surface 31, a reflective surface 32 connected to the light-incident surface 31, a light-emitting surface 33 connected to the light-incident surface 31 and opposite to the reflective surface 32, and a plurality of first microstructures 34 disposed on the reflective surface 32. Each of the first microstructures 34 is an asymmetric microstructure. The front light plate 4 has a reference surface 41 facing the light-emitting surface 33 of the light guide strip 3, and a plurality of second microstructures 42 disposed on the reference surface 41. For example, the point light source 2 may be a collection of a plurality of LEDs, correspondingly disposed on the light-incident surface of the light guide strip 3. When high brightness is not required, the point light source 2 can also be a single LED. Preferably, the light-emitting surface of the single LED can cover the light-incident surface 31 of the light guide strip 3. Through the above design, the light from the point light source 2 forms a line light source after passing through the light guide strip 3, and then forms a surface light source after passing through the front light plate 4. By means of the first microstructure 34 on the reflective surface 32 of the light guide strip 3, in conjunction with the second microstructure 42 of the front light plate 4, the light mixing distance at the light-incident edge of the front light plate 4 can be reduced, the display area can be increased, and the requirements of narrow bezel e-readers can be met.

[0023] For example, in this embodiment, a single LED 4 serves as the light source for the front light module, and its edges do not produce a bright spot distribution similar to that of conventional e-readers. In particular, the second microstructure 42 can further disperse the light evenly within the front light panel 4. It should be further noted that the front light panel 4 includes a light-emitting surface 43 connected to the reference surface 41. The light-emitting surface 43 has a plurality of reflective microstructures 44 (shown in FIG. 8), similar to the first microstructure 34 of the light guide strip 3, and the reflective microstructures 44 are arranged in a manner from sparse to dense along the light travel direction (third direction D3) on the light-emitting surface 43. More specifically, after the front light panel 4 receives light from the light guide strip 3, the light traveling in the Y direction (such as the third direction D3) inside the front light panel 4 can be reflected by the reflective microstructures 44 located on the light-emitting surface 43 and turned to the Z direction (second direction D2), encountering the display panel 5 located on the bottom surface as shown in FIG. 8, and being reflected and then emitted from the light-emitting surface 43 of the front light panel 4. For example, the reflective microstructure 44 is a microstructure recessed in the light-emitting surface 43, and its shape can be symmetrical or asymmetrical.

[0024] The front light module also includes at least one reflector 35 covering the light guide strip 3, and at least one light shield 36 covering the light guide strip 3. To facilitate the explanation of the detailed structure and the direction of light travel, a portion of the reflector 35 and the light shield 36 are removed in Figure 2. Figure 3 is a cross-sectional view at section line III-III in Figure 2. As shown in Figure 3, the reflector 35 covers the area of ​​the light guide strip 3 other than the light-emitting surface 33. Referring to Figures 2 and 4, the light shield 36 covers one end of the light guide strip 3 adjacent to the point light source 2 but does not block the light-incident surface 31 of the light guide strip 3. As shown in Figure 2, in this embodiment, the coverage positions of the reflector 35 and the light shield 36 do not overlap. It should be noted that the light-shielding member 36 is designed to prevent the light from the point light source 2 from directly escaping after entering the light guide strip 3, thus preventing light leakage. Therefore, it covers one end of the light guide strip 3 adjacent to the point light source 2 but does not block the light-incident surface 31, ensuring that the light from the point light source 2 can enter through the light-incident surface 31 and continue to travel within the light guide strip 3, while also providing sufficient light mixing distance. Since most of the light within the light guide strip 3 is reflected by the first microstructure 34 and then emanates from the light-emitting surface 33, while a small portion of the light is emitted from the reflective surface 32 of the light guide strip 3, the reflector 35 is used to reflect the light within the light guide strip 3 that is not reflected by the first microstructure 34 back into the light guide strip 3 and then out of the light-emitting surface 33, thereby improving light utilization. Therefore, except for the light-emitting surface 33 and the area covered by the light-shielding member 36, the light guide strip 3 is almost entirely shielded by the reflector 35.

[0025] Referring to Figure 5, which shows the top view of the light guide strip 3 after removing the reflector 35, the first microstructure 34 of the light guide strip 3 is an asymmetrical protrusion, and the distribution density of the first microstructure 34 is denser along the direction away from the point light source 2. That is, the arrangement density of the first microstructure 34 increases with the distance from the point light source 2. By arranging the first microstructure 34 with different densities, the light output can be more uniform. It should be noted that the first microstructure 34 is an integrally formed structure of the light guide strip 3, so there is no physical boundary line between the first microstructure 34 on the light guide strip 3 and the reflective surface 32.

[0026] Referring to Figures 6 and 7, the light guide strip 3 further includes a plurality of strip-shaped microstructures 37 disposed on the light-emitting surface 33, the strip-shaped microstructures 37 extending along a first direction D1. The first direction D1 is parallel to the optical axis of the point light source 2. As shown in Figure 3, each of the strip-shaped microstructures 37 is an arc-shaped surface with a central angle of 70 to 100 degrees, including endpoint values. In this embodiment, the light rays traveling along the X direction inside the light guide strip 3 are reflected by the first microstructure 34 on the reflecting surface 32 to form directional light rays. The strip-shaped microstructures 37 located on the light-emitting surface 33 can then spread the light rays that have been turned to the Y direction along the YZ plane formed by the Y and Z directions, which is beneficial for the second microstructure 42 of the lower front light plate 4 to receive the light. To further explain, the extension directions of the strip-shaped microstructures 37 and the second microstructure 42 are intersecting, which is beneficial for spreading the directional direction along different planes, such as the YZ plane and the XY plane, to increase the breadth of the light path. More specifically, each of the strip-shaped microstructures 37 has an arc-shaped periphery in a cross section in a second direction D2, the shape and length of which correspond to the arc shape and length of a central angle of 70 to 100 degrees, wherein the first direction D1 is perpendicular to the second direction D2.

[0027] Referring to Figure 7, which is an enlarged view of the area A framed in Figure 2, each of the first microstructures 34 of the light guide strip 3 is an asymmetrical microstructure, and each of the first microstructures 34 has a light-facing surface 341 for reflecting light. The angle θ between the light-facing surface 341 and the reflective surface 32 is 3 to 25 degrees, including the endpoint value.

[0028] The second microstructure 42 of the front light plate 4 extends along the second direction D2. Each of the second microstructures 42 of the front light plate 4 has a non-isosceles triangle cross-sectional shape along the first direction D1 and has a connected first functional surface 421 and a second functional surface 422. The first functional surface 421 is further away from the point light source 2 than the second functional surface 422. The first functional surface 421 and the second functional surface 422 of each second microstructure 42 extend along the second direction D2. A first angle θ1 is formed between the first functional surface 421 and the reference surface 41, and a second angle θ2 is formed between the second functional surface 422 and the reference surface 41. The first angle θ1 is smaller than the second angle θ2. The first angle θ1 is between 50 and 70 degrees, and the second angle θ2 is between 70 and 90 degrees, including endpoint values. Thus, by utilizing the asymmetrically arranged second microstructures 42 along the X-direction, light from the light guide strip 3 is received. In particular, these light rays have an angle of approximately 60-75 degrees with the Y-direction. Therefore, each smaller angle, the first angle θ1, can efficiently receive the aforementioned oblique light from the light guide strip 2 and efficiently reflect the light towards the Y-direction. In some embodiments, the cross-sectional shape of each second microstructure 42 can also be an isosceles triangle, which has the advantage of being easy to manufacture. It should be noted that the second microstructure 42 is a microstructure on the reference surface 41 of the front light plate 4 used to refract and reflect light, and the second microstructure 42 is an integrally formed structure on the front light plate 4; there is no physical boundary line between the second microstructure 42 on the front light plate 4 and the reference surface 41.

[0029] Referring to Figures 2 and 7, since the light guide strip 3 is covered by the light shield 36 and the reflector 35, when the light from the point light source 2 enters the light guide strip 3 through the light incident surface 31, it will be reflected within the light guide strip 3 and emitted from the area of ​​the light emitting surface 33 not covered by the light shield 36 and the reflector 35. The reflector 32 of the light guide strip 3 has asymmetrical first microstructures 34 formed on it. Light is reflected by the reflector 32 and the light-facing surface 341 of each of the first microstructures 34 and emitted from the light emitting surface 33. The angle θ between the light-facing surface 341 and the reflector 32 is designed to reflect light towards the light emitting surface 33. It should be noted that the reflector 35 has specular reflection characteristics, ensuring no light leakage and improving light reuse rate. In addition, since the specular reflection of the reflector 35 is a parallel reflection, and the first microstructure 34 on the light guide strip 3 has high light directivity, it is beneficial for the front light plate 4 to receive light at the correct angle.

[0030] Next, the strip-shaped microstructure 37 on the light-emitting surface 33 is an arc-shaped surface with a central angle of 70 to 100 degrees, further concentrating the light emission angle so that the light passing through the light-emitting surface 33 of the light guide strip 3 has an emission angle of 60 to 75 degrees. Utilizing the aforementioned structural design of the light guide strip 3, the light from the point light source 2 can be transformed into a uniform line light source, and the design of the first microstructure 34 ensures that the luminous intensity at each position in the line light source is equal. Furthermore, in this embodiment, the thickness of the light guide strip 3 gradually decreases along the direction away from the point light source 2, and the area of ​​the reflected light surface is smaller than the area of ​​the incident light surface, thus forming a wedge shape for the light guide strip 3. This shape design is intended to improve light utilization. For example, the light emitted by an LED has a specific angular range. To make it easier to understand, let's take the light rays L1, L2, and L3 shown in Figure 2 as an example. The light ray L1, which first encounters the first microstructure 34, will be reflected and redirected earlier than light ray L2, and light ray L2 will be reflected and redirected earlier than light ray L3. In this way, light rays at different angles can be dispersed and reflected along the first direction D1, thus improving the light utilization rate. However, if the size of the point light source 2 is small, the light guide strip 3 can also be a long strip with uniform thickness, not limited to the one disclosed in this embodiment.

[0031] The light from the point light source 2 is converted into a line light source by the light guide strip 3 and then enters the front light plate 4. At this time, the light is refracted by the second working surface 422 of each of the second microstructures 42, and then reflected by the first working surface 421, turning the light in a direction perpendicular to and away from the reference surface 41, so that the front light plate 4 forms a surface light source. Referring to FIG8, a display panel 5 is provided at a distance from the bottom surface of the front light plate 4 relative to the light emitting surface 43, which is a preferred embodiment of the e-reader of the present invention.

[0032] In summary, the front light module of the present invention utilizes the structural design of the light guide strip 3 to allow the light from the point light source 2 to form a line light source after passing through the light guide strip 3, and then form a surface light source after passing through the front light plate 4. Furthermore, by means of the first microstructure 34 on the reflective surface 32 of the light guide strip 3, in conjunction with the second microstructure 42 of the front light plate 4, the light mixing distance at the light incident edge of the front light plate 4 can be reduced, thereby increasing the display range and meeting the requirements of narrow bezel e-readers. This effectively achieves the purpose of the present invention.

[0033] However, the above description is only a preferred embodiment of the present invention and should not be construed as limiting the scope of the present invention. All simple equivalent changes and modifications made in accordance with the scope of the patent application and the description of the invention shall still fall within the scope of the patent of the present invention. [Simplified Explanation of the Diagram]

[0020] Figure 1 is a schematic diagram of a preferred embodiment of the front light module of the present invention; Figure 2 is a schematic diagram showing the partial removal of a light-shielding member and a reflective member that obscure a light guide strip in Figure 1; Figure 3 is a side cross-sectional view, showing the view along section line III-III in Figure 2, illustrating the relative positional relationship between the reflective member and the light guide strip; Figure 4 is a side schematic diagram illustrating the relative positional relationship between the light-shielding member and the light guide strip; Figure 5 is a top schematic diagram illustrating the morphology of the plurality of first microstructures of the light guide strip; Figure 6 is a bottom schematic diagram illustrating the morphology of the plurality of strip-shaped microstructures of the light guide strip; Figure 7 is a schematic diagram illustrating a partial enlargement of the area framed in Figure 2; and Figure 8 is a side schematic diagram of a preferred embodiment of the e-reader of the present invention.

Claims

1. A front light module for providing light to an image area of ​​a display panel, comprising: a point light source; a light guide strip for receiving light from the point light source, the light guide strip including a light-incident surface, a reflective surface connected to the light-incident surface, a light-emitting surface connected to the light-incident surface and opposite to the reflective surface, and a plurality of first microstructures disposed on the reflective surface, each of the first microstructures being an asymmetric microstructure; and a front light plate for receiving light emitted from the light guide strip, the front light plate having a reference surface facing the light-emitting surface of the light guide strip, and a plurality of second microstructures disposed on the reference surface; wherein... The front light panel is a plate-shaped body with a light-emitting surface connected to the reference surface. The reference surface of the front light panel extends along a first direction, the plate-shaped body is along a second direction which is the thickness direction, and the light-emitting surface of the front light panel unfolds into a plane along the first direction and a third direction, wherein the first direction, the second direction, and the third direction are perpendicular to each other. The light-emitting surface of the light guide strip extends along the reference surface, and the light guide strip gradually tapers along the first direction and the third direction and in a direction away from the point light source. The light from the point light source forms a linear light source after passing through the light guide strip, and then forms a surface light source after passing through the front light panel. The image area of ​​the display panel corresponds to the surface light source, and the light guide strip is located outside the image area of ​​the display panel.

2. The front light module as described in claim 1, wherein, Each of the first microstructures of the light guide strip has a light-facing surface for reflecting light, and the angle θ between the light-facing surface and the reflective surface is 3 to 25 degrees, including the endpoint values.

3. The front light module as described in claim 1, wherein, The first microstructure of the light guide strip is an asymmetrical protrusion, and the distribution density of the first microstructure is denser along the direction away from the point light source.

4. The front light module as described in claim 1, wherein, The cross-sectional shape of each of the second microstructures of the front light plate is an isosceles triangle.

5. The front light module as described in claim 1, wherein, Each of the second microstructures of the front light plate has a non-isosceles triangle cross-sectional shape and has a connected first working surface and a second working surface. The first working surface is further away from the point light source than the second working surface. The first working surface and the reference surface have a first included angle θ1, and the second working surface and the reference surface have a second included angle θ2. The first included angle θ1 is smaller than the second included angle θ2.

6. The front light module as described in claim 5, wherein, The first included angle θ1 is between 50 and 70 degrees, and the second included angle θ2 is between 70 and 90 degrees, including the endpoint values.

7. The front light module as described in claim 1, wherein, The light guide strip also includes a plurality of strip-shaped microstructures disposed on the light-emitting surface, the strip-shaped microstructures extending along the first direction.

8. The front light module as described in claim 7, wherein, The second microstructure extends along the second direction.

9. The front light module as described in claim 7, wherein, Each of the strip-shaped microstructures is an arc-shaped surface with a central angle of 70 to 100 degrees, including endpoint values.

10. The front light module as claimed in claim 1 further includes at least one reflector covering the light guide strip, the reflector covering the area outside the light-emitting surface of the light guide strip.

11. The front light module as claimed in claim 10 further includes at least one light-shielding member covering the light guide strip, the light-shielding member covering one end of the light guide strip adjacent to the point light source but not blocking the light-incident surface of the light guide strip.

12. The front light module as described in claim 11, wherein, The light-shielding component and the reflective component do not overlap.

13. An e-reader comprising a front light module as described in any one of claims 1 to 12, and a display panel spaced apart from the front light module.

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