TW202411703A - Multilayer light guide film, manufacturing method thereof and display device - Google Patents

Abstract

The present invention discloses a multilayer light guide film, a manufacturing method thereof and a display device. The multilayer light guide film includes a first light guide layer and a second light guide layer. A surface of the first light guide layer has a plurality of first microstructures, and the second light guide layer is disposed on the surface of the first light guide layer and directly contacts the surface of the first light guide layer, in which a surface of the second light guide layer has a plurality of second microstructures.

Description

Multi-layer light-guiding film, manufacturing method thereof and display device

The present invention relates to a multi-layer light-guiding film, a manufacturing method thereof and a display device.

As display devices are becoming thinner and lighter, light guide plates have been gradually replaced by light guide films. In order to achieve the expected optical effect, microstructures are formed on the light guide films. However, in the known method of forming a light guide film with a microstructure, a mold insert must first be formed through a lithography process and an electroplating process, wherein the mold insert has a pattern structure that complements the microstructure, and then the mold insert is imprinted on the light guide material to form a light guide film. Therefore, the above steps must be repeated to produce a multi-layer light guide film, resulting in complicated process steps and increased production costs. Furthermore, it is not easy to align the microstructures of different light-guiding films during the process of laminating the light-guiding films, and the adhesive layer used to affix the light-guiding films easily flows into the microstructures, thereby affecting the optical effect of the microstructures. In view of this, improving the above problems to reduce costs and improve the quality of multi-layer light-guiding films is indeed a topic that technical personnel in this field are committed to.

To at least partially solve the above-mentioned known problems, the present invention provides a multi-layer light-guiding film, a manufacturing method thereof and a display device to simplify the manufacturing process steps of the multi-layer light-guiding film and/or improve the quality of the multi-layer light-guiding film.

A technical solution adopted to solve the technical problem of the present invention is: providing a multi-layer light guide film, which includes a first light guide layer and a second light guide layer. The surface of the first light guide layer has a plurality of first microstructures, and the second light guide layer is arranged on the surface of the first light guide layer and directly contacts the surface of the first light guide layer, wherein the surface of the second light guide layer has a plurality of second microstructures.

Another technical solution adopted to solve the technical problem of the present invention is to provide a display device, which includes a display panel and a light source module arranged on one side of the display panel. The light source module includes the above-mentioned multi-layer light guide film.

Another technical solution adopted to solve the technical problem of the present invention is to provide a method for manufacturing a multi-layer light-guiding film. The manufacturing method includes providing a first light-guiding material layer, performing a first patterning process on the surface of the first light-guiding material layer to form a first light-guiding layer, directly arranging a second light-guiding material layer on the surface of the first light-guiding layer, and performing a second patterning process on the surface of the second light-guiding material layer to form a second light-guiding layer. The surface of the first light-guiding layer has a plurality of first microstructures, and the surface of the second light-guiding layer has a plurality of second microstructures.

In the present invention, since the second light-guiding layer can be directly formed on the first light-guiding layer, no additional adhesive layer is required between different light-guiding layers, thereby preventing the optical effect of the first microstructure from being affected by the adhesive layer, thereby improving the quality of the multi-layer light-guiding film. In addition, since the light-guiding layer can be directly formed through a patterning process, the process of manufacturing a multi-layer light-guiding film does not require the cumbersome step of making a mold, thereby significantly simplifying the process steps to reduce the manufacturing cost. Furthermore, since the positions of the microstructures of different light-guiding layers can be positioned through a patterning process, it can help to improve the alignment accuracy between the microstructures of different light-guiding layers, thereby improving the light-guiding efficiency.

In order to enable the technical personnel in this field to further understand the present invention, the following is a list of embodiments of the present invention, and the components and intended effects of the present invention are described in detail with the help of drawings. It should be noted that the drawings are simplified schematic diagrams, and therefore, only the components and combination relationships related to the present invention are shown to provide a clearer description of the basic structure or implementation method of the present invention, while the actual components and layout may be more complicated. In addition, for the convenience of explanation, the components shown in the various drawings of the present invention are not drawn in proportion to the number, shape, and size of the actual implementation, and the detailed proportions can be adjusted according to the design requirements.

Please refer to Figures 1 to 7, Figure 1 is a flow chart of the method for manufacturing a multi-layer light-guiding film of an embodiment of the present invention, Figures 2 to 7 are schematic diagrams of the structure of an embodiment of the present invention in different steps of manufacturing a multi-layer light-guiding film, and Figure 7 is a schematic cross-sectional diagram of a multi-layer light-guiding film of an embodiment of the present invention. As shown in Figure 1, the method for manufacturing a multi-layer light-guiding film provided in this embodiment includes steps S12 to S18. Steps S12 to S18 can be performed in sequence, for example. The manufacturing method of the present invention is not limited to steps S12 to S18, and other steps can also be performed before, after or between any of the steps shown. Steps S12 to S18 of Figure 1 will be further described in detail below in conjunction with Figures 2 to 7.

As shown in FIG. 1 and FIG. 2, in step S12, a first light-conducting material layer 12a may be provided first. The first light-conducting material layer 12a may be formed, for example, on a carrier (not shown). In the present embodiment, the first light-conducting material layer 12a may include a photoresist material, but is not limited thereto. For example, the photoresist material may, for example, include a photosensitive plastic material (for example, but not limited to a photosensitive resin material), but the present invention does not limit the composition of the photoresist material of the first light-conducting material layer 12a. The formation method of the first light-conducting material layer 12a may, for example, be determined according to the type of the photoresist material. For example, when the material of the first light-conducting material layer 12a includes a liquid photoresist material, the first light-conducting material layer 12a may be formed on the carrier, for example, by coating. Alternatively, when the material of the first light conductive material layer 12a includes a dry film photoresist material, the first light conductive material layer 12a can be formed on the carrier by, for example, laminating, but is not limited thereto.

As shown in FIG. 1 , FIG. 3 and FIG. 4 , after providing the first light guiding material layer 12a, step S14 may be performed to perform a first patterning process on the surface 12S of the first light guiding material layer 12a to form the first light guiding layer 12, wherein the surface 12S of the first light guiding layer 12 may have a plurality of first microstructures 12T. Since the first light guiding material layer 12a includes a photoresist material, the first patterning process may include, for example, an exposure process and a development process.

Specifically, as shown in FIG3 , the exposure process may include, for example, irradiating the first light-guiding material layer 12a with light L1, so that the irradiated portion can produce a chemical reaction. In some embodiments, the exposure process may include a grayscale imaging exposure process, such as a laser direct writing exposure machine or a grayscale mask, but the grayscale imaging exposure process is not limited thereto.

As shown in FIG4 , after the exposure process, a developing process may be performed to remove the portion of the first light guiding material layer 12a irradiated by the light ray L1, thereby forming a first light guiding layer 12 having a first microstructure 12T. The developing process may, for example, include using a developer to dissolve the portion of the first light guiding material layer 12a irradiated by the light ray L1, thereby achieving the purpose of removal, but is not limited thereto. It should be noted that in the embodiments of FIGS. 3 and 4 , the first light guiding material layer 12a includes a positive photoresist material as an example, but is not limited thereto. In other embodiments, the first light guiding material layer 12a may include a negative photoresist material, and the exposure process and the developing process thereof will not be described in detail herein. In some embodiments, after the developing process, the first light guiding layer 12 may, for example, be further subjected to a baking process, but is not limited thereto.

It should be noted that the exposure depth of the first light-guiding material layer 12a of the present embodiment may be, for example, related to the intensity of the light L1, so that the surface 12S of the first light-guiding material layer 12a may form a first microstructure 12T having an optical effect through an exposure process and a development process. In the embodiment of FIG. 4 , at least one first microstructure 12T may, for example, include a hole, wherein the hole may not penetrate the first light-guiding layer 12, but is not limited thereto. For example, the hole may have a side wall S1 and a side wall S2, and the side wall S1 and the side wall S2 may, for example, be connected at the bottom of the hole, so that the cross-sectional shape of the first microstructure 12T is V-shaped to achieve the desired optical effect. The side wall S1 may be neither perpendicular nor parallel to the surface 12S of the first light guide layer 12, that is, the side wall S1 and the normal direction ND perpendicular to the surface 12S have an angle greater than 0 degrees and less than 90 degrees, so that the depth of the side wall S1 in the normal direction ND perpendicular to the surface 12S can show continuous changes with different positions in the horizontal direction HD (such as the depth of the side wall S1 in the normal direction ND perpendicular to the surface 12S in FIG. 4 can decrease along the horizontal direction HD). In FIG. 4, the cross-sectional shape of the side wall S1 in the horizontal direction HD can, for example, include oblique lines (such as the oblique lines extending from the lower left to the upper right in FIG. 4), so that the first microstructure 12T can present the desired optical effect, that is, the first microstructure 12T can be used to adjust the direction of the light in the first light guide layer 12, but is not limited to this. The horizontal direction HD may be, for example, parallel to the surface 12S. In the present embodiment, the cross-sectional shape of the sidewall S1 in the horizontal direction HD may include, for example, a straight line, but is not limited thereto. In some embodiments, the cross-sectional shape of the sidewall S1 in the horizontal direction HD may include, for example, a curve or other suitable shapes. In the present embodiment, the sidewall S2 may be perpendicular to the surface 12S of the first light guide layer 12, so that the sidewall S1 and the sidewall S2 may form a V-shaped structure (i.e., the cross-sectional shape of the first microstructure 12T is V-shaped), but is not limited thereto. In some embodiments, the sidewall S2 may be neither perpendicular nor parallel to the surface 12S of the first light guide layer 12, that is, the sidewall S2 and the normal direction ND perpendicular to the surface 12S have an angle greater than 0 degrees and less than 90 degrees, so that the depth of the sidewall S2 in the normal direction ND perpendicular to the surface 12S can present a continuous change with different positions in the horizontal direction HD (e.g., the depth of the sidewall S2 in the normal direction ND perpendicular to the surface 12S can increase along the horizontal direction HD to form an oblique line extending from the upper left to the lower right), so that the sidewall S1 and the sidewall S2 can form a V-shaped structure. However, the cross-sectional shape of the first microstructure 12T of the present invention is not limited to the V-shape. In some embodiments, the cross-sectional shape of the first microstructure 12T may be a polygon with more than two sidewalls, a curved shape or other suitable shapes, but is not limited thereto. As shown in FIG3 and FIG4, in order to form the first microstructure 12T with a V-shaped structure in FIG4, the present invention may use a grayscale imaging exposure process as shown in FIG3, and in the area of the first light-guiding material layer 12a where the first microstructure 12T is predetermined to be formed, the irradiation amount of the light L1 varies in the horizontal direction HD (as in FIG3, in the area where at least a portion of a first microstructure 12T is predetermined to be formed, the irradiation amount of the light L1 decreases along the horizontal direction HD to form the first microstructure 12T whose depth in the normal direction ND perpendicular to the surface 12S may decrease along the horizontal direction HD as shown in FIG4). In some embodiments, the top view pattern of the hole in the normal direction ND can be designed according to actual needs, for example, it can include a rectangle, a circle, a strip or other suitable shapes. The top view pattern and the cross-sectional shape of the first microstructure 12T of the present invention can be adjusted according to actual needs, and the present invention does not limit the top view pattern and the cross-sectional shape of the first microstructure 12T. In some embodiments, when the hole is formed by an exposure process and a development process, the maximum aperture AP of the hole in the horizontal direction HD can be, for example, less than or equal to 5 microns, but the maximum aperture AP of the hole in the horizontal direction HD of the present invention is not limited thereto.

It is worth mentioning that, since the first light guide layer 12 of the present embodiment can be directly formed through an exposure process and a development process, there is no need to perform a complicated mold making step, thereby simplifying the process steps for making the first light guide layer 12 to reduce the time and cost of making the first light guide layer 12.

As shown in FIG. 1 and FIG. 5 , after forming the first light guide layer 12, step S16 may be performed to directly set the second light guide material layer 14a on the surface 12S of the first light guide layer 12. The second light guide material layer 14a may, for example, include a photoresist material. In the present embodiment, the photoresist material of the second light guide material layer 14a may include a dry film photoresist material. For example, the second light guide material layer 14a may be set on the first light guide layer 12 by lamination, but the method of setting the second light guide material layer 14a on the first light guide layer 12 of the present invention is not limited thereto. It should be noted that, since the second light conducting material layer 14a uses a dry film photoresist material, it is possible to prevent the second light conducting material layer 14a from flowing into the first microstructure 12T when the second light conducting material layer 14a is disposed on the surface 12S of the first light conducting layer 12, thereby improving the optical quality of the first microstructure 12T. In some embodiments, the second light conducting material layer 14a and the first light conducting material layer 12a may include the same or different photoresist materials. For example, the second light conducting material layer 14a may include a photosensitive plastic material (such as but not limited to a photosensitive resin material), but the present invention does not limit the composition of the photoresist material of the second light conducting material layer 14a.

As shown in FIG. 1 , FIG. 6 and FIG. 7 , step S18 may then be performed to perform a second patterning process on the surface 14S of the second light guiding material layer 14a to form the second light guiding layer 14, wherein the surface 14S of the second light guiding layer 14 may have a plurality of second microstructures 14T. Since the second light guiding material layer 14a includes a photoresist material, the second patterning process may include, for example, an exposure process and a development process, which may be the same as or similar to the first patterning process, but is not limited thereto.

Specifically, as shown in FIG6 , the exposure process of the second patterning process may, for example, include irradiating the second light-guiding material layer 14a with light L2 so that the irradiated portion can produce a chemical reaction. The exposure process may, for example, be the same as or similar to the exposure process of the first patterning process described above, and therefore will not be described in detail herein. For example, the exposure process of the second patterning process may include a grayscale imaging exposure process, but is not limited thereto.

As shown in FIG7 , after the exposure process, a development process may be performed to remove the portion of the second light-guiding material 14a irradiated by the light L2, thereby forming a second light-guiding layer 14 having a second microstructure 14T. In this way, the multi-layer light-guiding film 1 of the present embodiment may be formed. The development process of the second patterning process may be, for example, the same or similar to the development process of the first patterning process described above, and therefore will not be described in detail here. It should be noted that in the embodiments of FIGS. 6 and 7 , the second light-guiding material layer 14a includes a positive photoresist material as an example, but is not limited to this. In other embodiments, the second light-guiding material layer 14a may include a negative photoresist material, and its exposure process and development process will not be described in detail here. In some embodiments, after the development process, the second light-guiding layer 14 may be further subjected to a baking process, for example, but is not limited to this.

It should be noted that the exposure depth of the second light-conducting material layer 14a may also be related to the intensity of the light L2, so that the surface 14S of the second light-conducting material layer 14a may form a second microstructure 14T with an optical effect through an exposure process and a development process. In the embodiment of FIG. 7 , the second microstructure 14T may be, for example, the same as or similar to the first microstructure 12T described above, and may, for example, include a hole. For example, the hole of the second microstructure 14T may have a side wall S3 and a side wall S4, and the side wall S3 and the side wall S4 may, for example, be connected at the bottom of the hole, so that the cross-sectional shape of the second microstructure 14T is V-shaped. The side wall S3 may be neither perpendicular nor parallel to the surface 14S of the second light guide layer 14, that is, the side wall S3 and the normal direction ND of the surface 14S have an angle greater than 0 degrees and less than 90 degrees, so that the depth of the side wall S3 in the normal direction ND perpendicular to the surface 14S can show continuous changes with different positions in the horizontal direction HD (such as the depth of the side wall S3 in the normal direction ND perpendicular to the surface 14S in FIG. 7 can decrease along the horizontal direction HD). In FIG. 7, the cross-sectional shape of the side wall S3 in the horizontal direction HD can, for example, include an oblique line (such as the oblique line extending from the lower left to the upper right in FIG. 7), so that the second microstructure 14T can present the desired optical effect, that is, the second microstructure 14T can be used to adjust the direction of the light in the second light guide layer 14, but is not limited thereto. The horizontal direction HD can, for example, be parallel to the surface 14S. In this embodiment, the cross-sectional shape of the sidewall S3 in the horizontal direction HD may include, for example, a straight line, but is not limited thereto. In some embodiments, the cross-sectional shape of the sidewall S3 in the horizontal direction HD may include, for example, a curve or other suitable shapes. In this embodiment, the sidewall S4 may be perpendicular to the surface 14S of the second light guide layer 14, so that the sidewall S3 and the sidewall S4 may form a V-shaped structure, but is not limited thereto. In some embodiments, the sidewall S4 may be neither perpendicular nor parallel to the surface 14S of the second light guide layer 14, that is, the sidewall S4 and the normal direction ND perpendicular to the surface 14S have an angle greater than 0 degrees and less than 90 degrees, so that the depth of the sidewall S4 in the normal direction ND perpendicular to the surface 14S can present a continuous change with different positions in the horizontal direction HD (e.g., the depth of the sidewall S4 in the normal direction ND perpendicular to the surface 14S can increase along the horizontal direction HD to form an oblique line extending from the upper left to the lower right), so that the sidewall S3 and the sidewall S4 can form a V-shaped structure. However, the cross-sectional shape of the second microstructure 14T of the present invention is not limited to the V-shape. In some embodiments, the cross-sectional shape of the second microstructure 14T may be a polygon with more than two sidewalls, a curved shape, or other suitable shapes, but not limited thereto. In the present invention, the top view pattern and cross-sectional shape of the hole of the second microstructure 14T may be, for example, the same or similar to the top view pattern and cross-sectional shape of the hole of the first microstructure 12T, and does not penetrate the second light guide layer 14, but not limited thereto. The present invention does not limit the top view pattern and cross-sectional shape of the second microstructure 14T. As shown in FIG. 6 and FIG. 7 , in order to form the second microstructure 14T having a V-shaped structure in FIG. 7 , the present invention may use a grayscale imaging exposure process as shown in FIG. 6 , and in the area of the second light-guiding material layer 14a where the second microstructure 14T is to be formed, the irradiation amount of the light L2 varies in the horizontal direction HD (as shown in FIG. 6 , in the area where at least a portion of a second microstructure 14T is to be formed, the irradiation amount of the light L2 decreases along the horizontal direction HD to form the second microstructure 14T whose depth in the normal direction ND perpendicular to the surface 14S may decrease along the horizontal direction HD as shown in FIG. 7 ). In some embodiments, the top view pattern and cross-sectional shape of the second microstructure 14T may also be adjusted as required, and may be different from the top view pattern and cross-sectional shape of the first microstructure 12T, but is not limited thereto. In FIG. 7 , the second microstructure 14T may not overlap the first microstructure 12T in the normal direction ND. For example, when viewed from a top view (i.e., the normal direction ND), one of the second microstructures 14T may be located between two adjacent first microstructures 12T, but the present invention is not limited thereto. In some embodiments, at least a portion of the plurality of second microstructures 14T of the second light guide layer 14 may overlap at least a portion of the plurality of first microstructures 12T of the first light guide layer 12 in the normal direction ND. The present invention does not limit the relative arrangement positions of the plurality of first microstructures 12T of the first light guide layer 12 and the plurality of second microstructures 14T of the second light guide layer 14.

It should be noted that, since the second light guide layer 14 can be directly formed on the first light guide layer 12, an additional adhesive layer is not required between the second light guide layer 14 and the first light guide layer 12, thereby preventing the optical effect of the multi-layer light guide film 1 from being affected by the adhesive layer, thereby improving the quality of the multi-layer light guide film 1. In addition, the process steps for manufacturing the multi-layer light guide film 1 can be reduced, and/or the thickness of the multi-layer light guide film 1 in the normal direction ND can be reduced. In this embodiment, the second light guide layer 14 can have adhesiveness so that the second light guide layer 14 can be fixed on the first light guide layer 12, but it is not limited thereto. For example, the photoresist material of the second light guide material layer 14a may further include an adhesion promoter to enhance the adhesion between the second light guide layer 14 and the first light guide layer 12, but the invention is not limited thereto. In addition, since the first microstructure 12T and the second microstructure 14T can be formed through an exposure process and a development process, when performing the exposure process for manufacturing the second microstructure 14T, the exposure machine may first perform an alignment step on the pattern of the first light guide layer 12 and then perform exposure on the second light guide material layer 14a, which helps to improve the alignment accuracy between the first microstructure 12T and the second microstructure 14T, thereby improving the light guide efficiency. For example, when performing an exposure process for manufacturing the second microstructure 14T, the exposure machine may first perform an alignment step on at least one first microstructure 12T of the first light guiding layer 12 and then expose the second light guiding material layer 14a; or when performing a first patterning process on the surface 12S of the first light guiding material layer 12a in step S14, in addition to forming a plurality of first microstructures 12T on the surface 12S of the first light guiding layer 12, at least one alignment mark is also formed on the surface 12S of the first light guiding layer 12. When performing an exposure process for manufacturing the second microstructure 14T, the exposure machine may first perform an alignment step on the alignment mark of the first light guiding layer 12 and then expose the second light guiding material layer 14a. Furthermore, in the present embodiment, since the first light-guiding layer 12 and the second light-guiding layer 14 can be directly formed through an exposure process and a development process, in the process of manufacturing the multi-layer light-guiding film 1, there is no need to repeatedly manufacture multiple molds and perform multiple embossing processes, thereby simplifying the process steps of manufacturing the multi-layer light-guiding film 1 to reduce the manufacturing time and cost.

As shown in FIG7 , the multi-layer light guide film 1 provided in this embodiment may include a first light guide layer 12 and a second light guide layer 14. The surface 12S of the first light guide layer 12 may have a plurality of first microstructures 12T, and the second light guide layer 14 is disposed on the surface 12S of the first light guide layer 12 and directly contacts the surface 12S of the first light guide layer 12, wherein the surface 14S of the second light guide layer 14 may have a plurality of second microstructures 14T. For example, the surface 14S of the second light guide layer 14 opposite to the first light guide layer 12 may have the second microstructure 14T, but is not limited thereto. Specifically, the first microstructure 12T is disposed on the surface 12S of the first light guiding layer 12 facing the second light guiding layer 14, and the second microstructure 14T is disposed on the surface 14S of the second light guiding layer 14 facing away from the first light guiding layer 12. The refractive index of the medium in the first microstructure 12T may be different from the refractive index of the first light guiding layer 12, and the refractive index of the medium in the second microstructure 14T may be different from the refractive index of the second light guiding layer 14, so that the first microstructure 12T can adjust the angle of the light in the first light guiding layer 12, and the second microstructure 14T can adjust the angle of the light in the second light guiding layer 14. For example, the medium in the first microstructure 12T and/or the medium in the second microstructure 14T may be air, but is not limited thereto. In the present embodiment, the first light guide layer 12 and the second light guide layer 14 may include, for example, a photoresist material, and the photoresist material of the second light guide layer 14 may include, for example, a dry film photoresist material. In some embodiments, the first light guide layer 12 and the second light guide layer 14 may include the same or different photoresist materials. It should be noted that, through the above material selection, the first microstructure 12T and the second microstructure 14T can be directly formed by a patterning process, and can also have an optical effect of reflecting or refracting light.

The number of light-guiding layers of the multi-layer light-guiding film of the present invention is not limited to that shown in FIG. 7 above. For example, the multi-layer light-guiding film provided in the present embodiment may include at least three light-guiding layers. Please refer to FIG. 8, which is a cross-sectional schematic diagram of a multi-layer light-guiding film of another embodiment of the present invention. As shown in FIG. 8, the multi-layer light-guiding film 2 provided in the present embodiment may include three light-guiding layers. In other words, compared to the multi-layer light-guiding film 1 shown in FIG. 7, the multi-layer light-guiding film 2 of FIG. 8 may further include a third light-guiding layer 16, and the third light-guiding layer 16 may be directly disposed on the surface 14S of the second light-guiding layer 14. The surface 16S of the third light-guiding layer 16 opposite to the second light-guiding layer 14 may have a plurality of third microstructures 16T. In the embodiment of FIG. 8 , the material and formation method of the third light guide layer 16 and the top view pattern and cross-sectional shape of the third microstructure 16T may refer to the material and formation method of the second light guide layer 14 and the top view pattern and cross-sectional shape of the second microstructure 14T described above, but are not limited thereto. In the present embodiment, the third microstructure 16T may be, for example, the same as or similar to the first microstructure 12T and the second microstructure 14T described above, and may, for example, include a hole. The third microstructure 16T may have a side wall S5 and a side wall S6, and the side wall S5 and the side wall S6 may, for example, be connected at the bottom of the hole, so that the cross-sectional shape of the third microstructure 16T is V-shaped. In order to form the third microstructure 16T having a V-shaped structure in FIG. 8 , the present invention may use the grayscale imaging exposure process described above. In addition, in order to prevent the third light guiding material layer from filling into the second microstructure 14T when the material layer for forming the third light guiding layer 16 (or referred to as the third light guiding material layer) is disposed on the surface 14S of the second light guiding layer 14, the photoresist material of the third light guiding material layer of the present invention may include a dry film photoresist material. In some embodiments, the top view pattern and cross-sectional shape of the third microstructure 16T may also be adjusted as required and may be different from the first microstructure 12T and/or the second microstructure 14T, but is not limited thereto. The present invention does not limit the top view pattern and cross-sectional shape of the third microstructure 16T. As shown in FIG. 8 , the third microstructure 16T may not overlap the first microstructure 12T and the second microstructure 14T in the normal direction ND, but is not limited thereto. For example, from a top view direction (i.e., normal direction ND), one of the third microstructures 16T may be located between an adjacent first microstructure 12T and a second microstructure 14T. In some embodiments, at least a portion of the plurality of third microstructures 16T of the third light guide layer 16 may overlap at least a portion of the plurality of first microstructures 12T of the first light guide layer 12 and/or at least a portion of the plurality of second microstructures 14T of the second light guide layer 14 in the normal direction ND. The present invention does not limit the relative arrangement positions of the plurality of first microstructures 12T of the first light guide layer 12, the plurality of second microstructures 14T of the second light guide layer 14, and the plurality of third microstructures 16T of the third light guide layer 16.

As shown in Fig. 8, the first microstructure 12T is disposed on the surface 12S of the first light guiding layer 12 facing the second light guiding layer 14, the second microstructure 14T is disposed on the surface 14S of the second light guiding layer 14 facing the third light guiding layer 16, and the third microstructure 16T is disposed on the surface 16S of the third light guiding layer 16 facing away from the second light guiding layer 14. The refractive index of the medium in the third microstructure 16T may be different from the refractive index of the third light guiding layer 16, so that the third microstructure 16T can adjust the angle of the light in the third light guiding layer 16. For example, the medium in the third microstructure 16T may be air, but is not limited thereto.

Since the third light guide layer 16 can be directly formed on the second light guide layer 14, no additional adhesive layer is required between the third light guide layer 16 and the second light guide layer 14. In this embodiment, the third light guide layer 16 may have adhesiveness so that the third light guide layer 16 can be fixed on the second light guide layer 14, but the present invention is not limited thereto. For example, the photoresist material used to form the third light guide layer 16 may further include an adhesiveness promoter to enhance the adhesion between the third light guide layer 16 and the second light guide layer 14, but the present invention is not limited thereto. In addition, when performing the exposure process for manufacturing the third microstructure 16T, the exposure machine can first perform an alignment step on the pattern of the second light guiding layer 14 and then expose the photoresist material used to form the third light guiding layer 16, which helps to improve the alignment accuracy between the third microstructure 16T and the second microstructure 14T, thereby improving the light guiding efficiency. For example, when performing an exposure process for manufacturing the third microstructure 16T, the exposure machine may first perform an alignment step on at least one second microstructure 14T of the second light guiding layer 14 and then expose the photoresist material used to form the third light guiding layer 16; or when performing a second patterning process on the surface 14S of the second light guiding material layer 14a in step S18, in addition to forming a plurality of second microstructures 14T on the surface 14S of the second light guiding material layer 14a, at least one alignment mark is also formed on the surface 14S of the second light guiding material layer 14a. When performing an exposure process for manufacturing the third microstructure 16T, the exposure machine may first perform an alignment step on the alignment mark of the second light guiding layer 14 and then expose the photoresist material used to form the third light guiding layer 16.

Similarly, in some embodiments, at least one light guiding layer may be stacked sequentially on the surface 16S of the third light guiding layer 16 of Figure 8 to form a multi-layer light guiding film having at least four light guiding layers, and the material and formation method of the at least one light guiding layer and the top view pattern and cross-sectional shape of the microstructure of the at least one light guiding layer may, for example, refer to the material and formation method of the third light guiding layer 16 and the top view pattern and cross-sectional shape of the third microstructure 16T mentioned above, and therefore will not be elaborated here.

In summary, the multi-layer light-guiding film of the present invention includes at least two light-guiding layers stacked on each other, that is, the multi-layer light-guiding film of the present invention includes N light-guiding layers stacked on each other, and N is a positive integer greater than or equal to 2. The N light-guiding layers include the first to Nth light-guiding layers stacked in sequence in the normal direction ND, and the first to Nth light-guiding layers include the first to Nth microstructures, respectively. The i-th microstructure is disposed on the surface of the i-th light-guiding layer facing the (i+1)th light-guiding layer, and the N-th microstructure is disposed on the surface of the N-th light-guiding layer facing away from the (N-1)th light-guiding layer, wherein i is a positive integer greater than or equal to 1 and less than or equal to (N-1). The method for manufacturing a multi-layer light-guiding film may include performing a first patterning process on the surface of a first light-guiding material layer to form a first light-guiding layer having a plurality of first microstructures, then directly disposing a j-th light-guiding material layer on the surface of the (j-1)-th light-guiding layer, and performing a j-th patterning process on the surface of the j-th light-guiding material layer opposite to the (j-1)-th light-guiding layer to form a j-th light-guiding layer having a plurality of j-th microstructures, wherein j is a positive integer greater than or equal to 2 and less than or equal to N. The first to N-th patterning processes may, for example, include an exposure process and a developing process, but are not limited thereto. The exposure process of the first to N-th patterning processes may include a grayscale imaging exposure process, but are not limited thereto. The material of the first light guiding layer (i.e., the first light guiding material layer) may include a liquid photoresist material or a dry film photoresist material, and the materials of the second to Nth light guiding layers (i.e., the second to Nth light guiding material layers) may include a dry film photoresist material to prevent the jth light guiding material layer from filling into the (j-1)th microstructure of the (j-1)th light guiding layer when the jth light guiding material layer is disposed on the surface of the (j-1)th light guiding layer. No additional adhesive layer is required between the jth light guiding layer and the (j-1)th light guiding layer, thereby preventing the optical effect of the multi-layer light guiding film from being affected by the adhesive layer, thereby improving the quality of the multi-layer light guiding film. The second to Nth light guiding material layers may have adhesiveness so that the jth light guiding layer can be fixed on the (j-1)th light guiding layer, but is not limited thereto. For example, the photoresist material of the second to Nth light guiding material layers may further include an adhesion promoter to enhance the adhesion between the jth light guiding layer and the (j-1)th light guiding layer, but the present invention is not limited thereto. The refractive index of the medium in the first to Nth microstructures may be different from the refractive index of the first to Nth light guiding layers, respectively, so that the first to Nth microstructures may adjust the angle of the light in the first to Nth light guiding layers, respectively. For example, the medium in the first to Nth microstructures may be air, but the present invention is not limited thereto. In addition, when performing the exposure process for manufacturing the jth microstructure of the jth light guiding layer, the exposure machine may first perform an alignment step on the pattern of the (j-1)th light guiding layer and then expose the jth light guiding material layer, which helps to improve the alignment accuracy between the jth microstructure of the jth light guiding layer and the (j-1)th microstructure of the (j-1)th light guiding layer, thereby improving the light guiding efficiency.

Please refer to FIG9 , which is a schematic cross-sectional view of a display device according to an embodiment of the present invention. As shown in FIG9 , the display device 3 may include a display panel 32 and a light source module 34, and the light source module 34 is disposed on one side of the display panel 32, wherein the light source module 34 may include a multi-layer light-guiding film 36. In the present embodiment, the display panel 32 may have a display surface 32S1 and a back surface 32S2 opposite to the display surface 32S1, and the light source module 34 may be disposed on the back surface 32S2 of the display panel 32, so that the light generated by the light source module 34 may be used as a backlight source for the display panel 32, but the present invention is not limited thereto. The display surface 32S1 may, for example, be the surface of the display panel 32 facing the user UR. The multi-layer light-guiding film 36 shown in FIG9 is for illustration only, and may include the multi-layer light-guiding film of any of the above-mentioned embodiments, and therefore will not be described in detail here. In FIG9 , the light source module 34 may further include a light source 38, which is disposed on a side surface 36S of the multi-layer light guide film 36, so that light from the light source 38 can enter the multi-layer light guide film 36 from the side surface 36S of the multi-layer light guide film 36 to adjust the light direction of the light source 38 and transmit the light to the display panel 32. In some embodiments, the display panel 32 may include, for example, a transmissive display panel, such as a transmissive liquid crystal display panel or other suitable display panels.

Please refer to FIG. 10 , which is a cross-sectional schematic diagram of a display device of another embodiment of the present invention. As shown in FIG. 10 , the difference between the display device 4 provided in this embodiment and the display device 3 shown in FIG. 9 is that the position of the light source module relative to the display panel is different. As shown in FIG. 10 , the display device 4 may include a display panel 32a and a light source module 34a, and the light source module 34a is disposed on one side of the display panel 32a, wherein the light source module 34a may include a multi-layer light-guiding film 36a. In this embodiment, the display panel 32a may have a display surface 32aS1 and a back surface 32aS2 opposite to the display surface 32aS1, and the light source module 34a may be disposed on the display surface 32aS1 of the display panel 32a, so that the light generated by the light source module 34a can be used as a front light source (front light) of the display panel 32a, but is not limited thereto. The display surface 32aS1 may be, for example, the surface of the display panel 32a facing the user UR. The multi-layer light-guiding film 36a shown in FIG. 10 is for illustration only and may include the multi-layer light-guiding film of any of the above-mentioned embodiments, and therefore will not be described in detail here. In FIG. 10 , the light source module 34a may also include a light source 38a, which is disposed on the side 36aS of the multi-layer light-guiding film 36a, so that the light of the light source 38a can enter the multi-layer light-guiding film 36a from the side 36aS of the multi-layer light-guiding film 36a to adjust the light direction of the light source 38a and transmit the light to the display panel 32a. In some embodiments, the display panel 32a may, for example, include a reflective display panel, such as a reflective liquid crystal display panel, electronic paper or other suitable display panels.

In summary, in the method for manufacturing a multi-layer light-guiding film of the present invention, since the second light-guiding layer can be directly formed on the first light-guiding layer, no additional adhesive layer is required between different light-guiding layers, thereby preventing the optical effect of the first microstructure from being affected by the adhesive layer, thereby improving the quality of the multi-layer light-guiding film. In addition, the process steps for manufacturing the multi-layer light-guiding film can be simplified, and/or the thickness of the multi-layer light-guiding film in the normal direction can be reduced. In addition, since the light-guiding layer can be directly formed through an exposure process and a development process, the process of manufacturing the multi-layer light-guiding film does not require the cumbersome step of making a mold core, thereby significantly simplifying the process steps to reduce the manufacturing cost. Furthermore, since the positions of the microstructures of different light-guiding layers can be positioned by the machine in the exposure process, it can help improve the alignment accuracy between the microstructures of different light-guiding layers, thereby improving the light-guiding efficiency. The above is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

1,2: multi-layer light-guiding film 12: first light-guiding layer 12a: first light-guiding material layer 12S,14S,16S: surface 12T: first microstructure 14: second light-guiding layer 14a: second light-guiding material layer 14T: second microstructure 16: third light-guiding layer 16T: third microstructure 3: display device 32,32a: display panel 32S1,32aS1: display surface 32S2,32aS2: back surface 34,34a: light source module 36,36a: multi-layer light-guiding film 36S,36aS: side surface 38,38a: light source AP: maximum aperture HD: horizontal direction L1,L2: light ND: normal direction S1,S2,S3,S4,S5,S6: Sidewall S12,S14,S16,S18: Steps UR: User

FIG. 1 is a flow chart of a method for manufacturing a multi-layer light-guiding film according to an embodiment of the present invention, FIG. 2 to FIG. 7 are schematic diagrams of the structure of an embodiment of the present invention in different steps of manufacturing a multi-layer light-guiding film, FIG. 8 is a schematic cross-sectional view of a multi-layer light-guiding film according to another embodiment of the present invention, FIG. 9 is a schematic cross-sectional view of a display device according to an embodiment of the present invention, and FIG. 10 is a schematic cross-sectional view of a display device according to another embodiment of the present invention.

1: Multi-layer light-guiding film

12: First light guide layer

12S,14S: Surface

12T: First microstructure

14: Second light guide layer

14T: Second microstructure

HD: horizontal direction

ND: Normal direction

S1,S2,S3,S4: Side walls

Claims (10)

A multi-layer light-guiding film comprises: a first light-guiding layer, wherein the surface of the first light-guiding layer has a plurality of first microstructures; and a second light-guiding layer, disposed on the surface of the first light-guiding layer and in direct contact with the surface of the first light-guiding layer, wherein the surface of the second light-guiding layer has a plurality of second microstructures. The multi-layer light-guiding film as described in claim 1, wherein the first light-guiding layer and the second light-guiding layer comprise photoresistive materials. A multi-layer light-guiding film as described in claim 1, wherein one of the plurality of first microstructures comprises a hole. A display device, comprising: a display panel; and a light source module, disposed on one side of the display panel, wherein the light source module comprises a multi-layer light-guiding film as described in claim 1. A display device as described in claim 4, wherein the light source module is disposed on a display surface of the display panel or on a surface of the display panel opposite to the display surface. A method for manufacturing a multi-layer light-guiding film, comprising: providing a first light-guiding material layer; performing a first patterning process on the surface of the first light-guiding material layer to form a first light-guiding layer, wherein the surface of the first light-guiding layer has a plurality of first microstructures; directly disposing a second light-guiding material layer on the surface of the first light-guiding layer; and performing a second patterning process on the surface of the second light-guiding material layer to form a second light-guiding layer, wherein the surface of the second light-guiding layer has a plurality of second microstructures. The method for manufacturing a multi-layer light-guiding film as described in claim 6, wherein the first light-guiding material layer and the second light-guiding material layer include photoresist materials. The method for manufacturing a multi-layer light-guiding film as described in claim 7, wherein the first patterning process and the second patterning process include an exposure process and a development process. A method for manufacturing a multi-layer light-guiding film as described in claim 8, wherein the exposure process includes a grayscale imaging exposure process. The method for manufacturing a multi-layer light-guiding film as described in claim 7, wherein the material of the second light-guiding material layer includes a dry film photoresist material.

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