Touch display

Abstract

A touch display includes a cover plate, a chassis, a front light module, a touch module, and a reflective display module. The cover plate is provided with an ink layer. The front light module includes a light guide plate and a light source module including a light-emitting diode, a first reflective layer, and a second reflective layer. The touch module has a side facing the light source module, and the light guide plate has an extension portion outside the vertical projection range of the touch module. The extension portion has an exposed part that is not covered and is exposed to air. The reflective display module includes a reflective display and a light-blocking element. The reflective display does not overlap with the light-emitting diode in the vertical projection of the cover plate. The light-emitting diode, the first reflective layer, the second reflective layer, and a side entry light surface of the light guide plate form a first light mixing area. The side of the touch module, the ink layer, the chassis, and the light-blocking element form a second light mixing area, with the extension portion located within the second light mixing area.

Description

Technical Field

[0001] The present disclosure relates to a touch display device, and in particular to a reflective touch display device. Prior Art

[0002] E-book readers utilize bi-stable display technology, consuming power only when the display changes. This reduces power consumption by over 90% compared to conventional self-luminous displays, achieving environmental benefits in terms of energy conservation and energy saving. Furthermore, replacing traditional paper books with e-books can reduce carbon emissions from deforestation, embodying sustainable value through green technology.

[0003] Generally speaking, reflective display devices often feature a front light guide plate (LGP) to provide display functionality even in dark or dimly lit areas. However, this also hinders the need for thinner designs when further integrating a touch panel to form a touch display device. Existing technologies have attempted to reduce the thickness of the LGP as a solution. However, thinning the LGP can lead to other issues, potentially causing optical defects in the touch display device, such as hotspots.

[0004] To address the optical issues caused by thinning the light guide plate (LGP), the prior art TWI855599 proposed several solutions. For example, by placing a light-shielding film between the light-emitting element and the top of the LGP and a flexible printed circuit board (FPC) at the bottom, the optical performance of the thinned LGP was improved. Light coupling efficiency was also enhanced by designing the ratio of the light-emitting element to the LGP thickness. However, covering the light-emitting element with a light-shielding film in this prior art results in partial light absorption, reducing overall light utilization efficiency. Furthermore, this prior art did not further consider the changes in light mixing effects as the LGP thickness is reduced. Consequently, light uniformity is poor at the end of the LGP adjacent to the light source, potentially causing localized hot spots (light spots) or uneven illumination. Therefore, balancing the thinness of touch display devices with light uniformity is a worthy area of ​​research. Summary of the Invention

[0005] According to some embodiments of the present disclosure, a touch display device includes a cover plate, a housing, a frontlight module, a touch module, and a reflective display module. The cover plate has a viewing area and a peripheral area, the peripheral area being provided with an ink layer. The housing and the cover plate together form a storage space. The frontlight module includes a light guide plate and a light source module. The light guide plate has a side light incident surface. The light source module includes a plurality of light-emitting diodes, a first reflective layer, and a second reflective layer. Each light-emitting diode has a light-emitting surface facing the side light incident surface, a reflective surface opposite the light-emitting surface, and a continuous light-uniforming surface surrounding the light-emitting surface and the reflective surface. The first reflective layer covers a portion of the light guide plate. The second reflective layer supports a portion of the light guide plate. The touch module is located between the cover plate and the frontlight module and has a touch module side facing the light source module. The light guide plate has an extension beyond the vertical projection of the touch module onto the light guide plate. The extension has an exposed portion not covered by the first reflective layer or the second reflective layer, and the exposed portion is exposed to air. The reflective display module includes a reflective display and a shading element. The vertical projection of the reflective display on the cover plate does not overlap with the vertical projection of the light-emitting diode on the cover plate. The shading element is connected to the reflective display. The light-emitting diode, the first reflective layer, the second reflective layer, and the side incident surface of the light guide plate form a first light mixing area. The side surface of the touch module, the ink layer, the housing, and the shading element form a second light mixing area, and the extended portion of the light guide plate is located in the second light mixing area.

[0006] In some embodiments of the present disclosure, the light guide plate has an upper surface and a lower surface opposite to the upper surface, and the exposed portion on the upper surface and the lower surface is a substantially flat surface and directly contacts the air.

[0007] In some embodiments of the present disclosure, the light guide plate has an upper surface and a lower surface opposite to the upper surface, and the length of the exposed portion on the upper surface is shorter than the length of the exposed portion on the lower surface.

[0008] In some embodiments of the present disclosure, the continuous light-homogenizing surface is a light-transmitting matte surface.

[0009] In some embodiments of the present disclosure, the front light module further includes a first optical adhesive layer and a second optical adhesive layer, wherein the first optical adhesive layer is located between the first reflective layer and the light guide plate, and the second optical adhesive layer is located between the second reflective layer and the light guide plate, and the total thickness of the light guide plate, the first optical adhesive layer, and the second optical adhesive layer is less than the thickness of each light-emitting diode.

[0010] In some embodiments of the present disclosure, the lower surface of the second optical adhesive layer is flush with the lower surface of each light-emitting diode.

[0011] In some embodiments of the present disclosure, the light transmittance of each of the first optical adhesive layer and the second optical adhesive layer is 91% to 99.9%.

[0012] In some embodiments of the present disclosure, a vertical projection of the side incident surface of the light guide plate on the cover plate does not overlap with a vertical projection of the reflective display on the cover plate.

[0013] In some embodiments of the present disclosure, the reflective display has a display side surface facing the light-emitting surface of each light-emitting diode, and a vertical projection of the display side surface on the light guide plate falls within the exposed portion.

[0014] In some embodiments of the present disclosure, the first reflective layer, the second reflective layer, the side light incident surface of the light guide plate, and the light emitting surface of each light emitting diode enclose an air cavity, and the first reflective layer has a slope at a position corresponding to the air cavity.

[0015] According to the above-mentioned embodiment of the present disclosure, by providing a dual light mixing area and extending the light guide plate and arranging the extended portion in the light mixing area, it can be ensured that the thinning of the light guide plate to meet the thin design of the touch display device will not affect the overall optical performance of the touch display device. Simple diagram description

[0016] To make the above and other objects, features, advantages and embodiments of the present disclosure more clearly understood, the accompanying drawings are described as follows: Figure 1 is a cross-sectional schematic diagram of a touch display device according to some embodiments of the present disclosure; Figure 2 is a partially enlarged schematic diagram of area R1 in Figure 1; and Figure 3 is a top-down schematic diagram of some components in a touch display device according to some embodiments of the present disclosure. Implementation Method

[0017] The following drawings illustrate several embodiments of the present disclosure. For clarity, many practical details are included in the following description. However, these practical details should not be construed as limiting the present disclosure. Furthermore, for ease of viewing, the dimensions of the elements in the drawings are not drawn to scale. Furthermore, relative terms such as "lower" and "upper" may be used herein to describe the relationship of one element to another, as shown in the drawings. It should be understood that relative terms are intended to encompass different orientations of the device in addition to those shown in the drawings. Furthermore, terms such as "first" and "second" mentioned in the specification or patent claims are used solely to name different elements or to distinguish between different embodiments or scopes, and are not intended to limit the upper or lower limits on the number of elements or to define the order in which the elements may be manufactured or disposed.

[0018] Please refer to Figure 1, which is a schematic cross-sectional view of a touch display device 100 according to some embodiments of the present disclosure. The touch display device 100 includes a cover plate 110, a housing 120, a front light module 200, a touch module 140, and a reflective display module 150. In other words, the touch display device 100 of the present disclosure is a reflective touch display device. The following description will provide a detailed explanation of each of these components.

[0019] The cover plate 110 has a viewing area VA and a peripheral area PA. An ink layer 112 is provided in the peripheral area PA on the side of the cover plate 110 facing the touch module 140 to prevent light leakage. In some embodiments, the ink layer 112 may extend from the edge 111 of the cover plate 110 toward the viewing area VA, creating a boundary between the peripheral area PA and the viewing area VA. In some embodiments, the ink layer 112 may include three stacked layers, with a black ink layer located on the side relatively close to the touch module 140 and two white ink layers located on the side relatively close to the cover plate 110. In some embodiments, the cover plate 110 is made of a material with a certain degree of rigidity, such as glass, quartz, or a suitable polymer (e.g., polycarbonate, polymethyl methacrylate), to provide protection for the touch display device 100.

[0020] The housing 120 and the cover plate 110 together form a housing space Y, and the front light module 200, the touch module 140, and the reflective display module 150 are all located within this housing space Y. In some embodiments, the housing 120 and the cover plate 110 together enclose a rectangular housing space Y. In some embodiments, the housing 120 can be attached to the cover plate 110 using a sealant 160 disposed in the peripheral area PA of the cover plate 110. In some embodiments, the inner surface 121 of the housing 120 can be made of stainless steel, which has the property of reflecting light. In other words, the inner surface 121 of the housing 120 can be a reflective surface.

[0021] The frontlight module 200 is configured to provide frontlight illumination for the touch display device 100 and includes a light guide plate 210 and a light source module 220. The light source module 220 is used to provide light to the light guide plate 210 and cooperates with the light guide plate 210 to improve light uniformity. The light guide plate 210 has an upper surface 211, a lower surface 213, and a side light-entry surface 215. The upper surface 211 is opposite the lower surface 213, while the side light-entry surface 215 connects the upper and lower surfaces 211 and faces the light-emitting diode 222 in the light source module 220. In other words, light emitted by the light-emitting diode 222 enters the light guide plate 210 in the form of side light. In some embodiments, the light guide plate 210 may be made of polycarbonate, polymethacrylate, polyolefin, or a combination thereof, and is preferably designed to be flexible.

[0022] To accommodate the thinner design of the frontlight module 200, the thickness H1 of the light guide plate 210 disclosed herein can be designed to be between 0.1 mm and 0.25 mm (e.g., 0.15 mm, 0.20 mm). However, while thinning the light guide plate 210 contributes to the thinner design of the frontlight module 200, it can also lead to other problems that can cause optical defects in the frontlight module 200. For example, the thinned light guide plate 210 reduces the light mixing space due to the shorter optical path, which can cause uneven light (i.e., hotspot issues). To address this issue, the present disclosure not only thins the light guide plate 210 to accommodate the thinner design of the frontlight module 200, but also improves the uneven light problem resulting from the thinning of the light guide plate 210 through at least a dual light mixing mechanism, thereby taking into account the overall applicability of the touch display device 100. Detailed implementation methods will be described later.

[0023] The light source module 220 includes a plurality of light-emitting diodes 222, a first reflective layer 224, and a second reflective layer 226. Each light-emitting diode 222 is disposed adjacent to the light guide plate 210 and has a light-emitting surface 223 facing the side light-entering surface 215 of the light guide plate 210. Furthermore, each light-emitting diode 222 also has a reflective surface 225 (see FIG. 2 ) opposite the light-emitting surface 223 and a continuous light-distributing surface 227 (see FIG. 2 ) surrounding the light-emitting surface 223 and the reflective surface 225. In some embodiments, the continuous light-distributing surface 227 may be a translucent matte surface, such as an atomized surface or a translucent material with a microstructure. In some embodiments, the continuous light-distributing surface 227 may be made of a partially translucent material with a high haze, such as a heat-resistant polymer with a translucent, milky white, soft haze. In some embodiments, the light source module 220 may include a housing (e.g., an encapsulating housing) that completely encapsulates the light-emitting diode 222, and the continuous light-homogenizing surface 227 of the light-emitting diode 222 may be formed from the same material as the housing. This means that light does not simply pass through a two-dimensional, light-transmitting matte surface, but rather through a light-transmitting matte structure with a certain thickness (e.g., the thickness of a single side of the housing). When the continuous light-homogenizing surface 227 is a light-transmitting matte surface, it diffuses light that is not directly emitted from the light-emitting surface 223, thereby reducing localized overbrightness or light spots (hot spots). In contrast, with the commonly used parabolic reflector lampshade, when the continuous light-homogenizing surface 227 is a non-transparent reflective surface, the light that is not directly emitted from the light-emitting surface 223 is reflected by the reflective surface, resulting in a concentrated light path. While this improves light efficiency, it can also over-concentrate the light entering the light guide plate 210, leading to uneven brightness distribution.

[0024] In some embodiments, the LED 222 may have an elongated light-emitting surface 223, such as a rectangular one. Compared to a point light source, an elongated light-emitting surface 223 reduces light diffraction and provides a more uniform light distribution. Furthermore, by elongating the light-emitting surface 223 so that it extends horizontally, combined with a continuous light-leveling surface 227 made of a translucent soft-fog material, the pitch between adjacent LEDs 222 is effectively blurred. This reduces the noticeable bright / dark boundary caused by the arrangement of light sources, as well as hot spots caused by optical interference due to regularly spaced point light sources, thereby improving overall optical uniformity. In some embodiments, the LED 222 uses the SSWM31CQ2-NAA LED (available from Seoul Semiconductor), with dimensions of 3.0 mm (width) × 0.85 mm (length) × 0.3 mm (thickness H4, see Figure 2).

[0025] Please refer to Figures 1 and 3 simultaneously, with Figure 3 being a schematic top view of certain components of the touch display device 100 according to some embodiments of the present disclosure. In some embodiments, a plurality of light-emitting diodes 222 are arranged spaced apart from one another on the second reflective layer 226 along the side incident surface 215 of the light guide plate 210. The pitch P between two adjacent light-emitting diodes 222 is 12 mm to 15 mm (e.g., 12.5 mm, 13 mm, 13.5 mm, 14 mm, or 14.5 mm), where the pitch P refers to the distance between the center points of two adjacent light-emitting diodes 222. In some embodiments, the horizontal distance d1 between the light-emitting surface 223 of the light-emitting diode 222 and the side incident surface 215 of the light guide plate 210 can be 0.1275 mm to 0.850 mm. By setting this horizontal distance d1, light can propagate through the air and diffuse appropriately before entering the light guide plate 210. This also allows the light-emitting surface 223 of the LED 222 to maintain a consistent distance from the first reflective layer 224, the second reflective layer 226, and the side incident surface 215. This creates a structure similar to a photographic light box in the space between the LED 222 and the light guide plate 210, thereby achieving a uniform light distribution effect and avoiding localized overbrightness or the generation of bright and dark boundaries. If the horizontal distance d1 is too small, the light may be overly concentrated in a localized area, resulting in uneven brightness. This may also produce overly bright spots (hot spots) in specific areas due to diffraction of the light source. If the horizontal distance d1 is too large, some light may be excessively divergent before entering the light guide plate 210, potentially causing stray light outside the side incident surface 215, leading to unintended illumination and reducing the amount of light entering the light guide plate 210, thereby lowering the overall illumination brightness. In some embodiments, the lower limit of the horizontal distance d1 can be calculated as follows: (thickness H1 of the light guide plate 210 + thickness H2 of the first optical adhesive layer 240 + thickness H3 of the second optical adhesive layer 250) / 2. This design takes into account the distance between the light source (LED 222) and each reflective wall, ensuring that the amount of light reflected back in different directions is similar, avoiding excessive concentration of reflected light in a single direction and thus improving the uniformity of light distribution.

[0026] Please return to Figure 1. The first reflective layer 224 covers a portion of the upper surface 211 of the light guide plate 210, and the second reflective layer 226 supports a portion of the lower surface 213 of the light guide plate 210. In some embodiments, the first reflective layer 224 further extends to the upper surface of the light-emitting diode 222 (i.e., the continuous light-homogenizing surface 227 at the top in Figure 2) to cover the entire light-emitting diode 222, and the second reflective layer 226 further extends to the lower surface of the light-emitting diode 222 (i.e., the continuous light-homogenizing surface 227 at the bottom in Figure 2) to support the entire surface of the light-emitting diode 222. In terms of the overall structure, the side light-incident surface 215 of the light guide plate 210, the light-emitting surface 223 of the light-emitting diode 222, the first reflective layer 224, and the second reflective layer 226 collectively enclose an air cavity S. The configuration of the first reflective layer 224 and the second reflective layer 226 constrains the direction of light reflection, allowing the light to escape the light-emitting surface 223 and enter the air cavity S. Within the air cavity S, the light is reflected by the first reflective layer 224 and the second reflective layer 226, adjusting its direction and allowing it to enter the light guide plate 210. This mechanism, through the structure surrounding the air cavity S, reduces the directivity of light emitted by the highly directional LEDs 222 through reflection (i.e., the light entering the light guide plate 210 is scattered more). This homogenization process occurs before the light is transmitted through the light guide plate 210. Therefore, the light traveling through the light guide plate 210 is more evenly distributed, reducing localized hot spots and improving overall optical uniformity. In some embodiments, the first reflective layer 224 covers all LEDs 222 and the space between adjacent LEDs 222 (i.e., the spacing P shown in FIG. 3 ). In some embodiments, the second reflective layer 226 may be an opaque, reflective surface of the flexible printed circuit board 230 connected to the light-emitting diode 222, such as the opaque, reflective surface located above the flexible printed circuit board 230 in FIG. In some embodiments, the second reflective layer 226 may be an ink coating, a chemically plated layer, or an electroplated layer, or the white surface of the flexible printed circuit board 230 itself (i.e., the reflective function is provided by selecting a white flexible printed circuit board 230). In some embodiments, the light reflectivity of the first reflective layer 224 may be 60% to 80% (e.g., 65%, 70%, or 75%), and the light reflectivity of the second reflective layer 226 may be 55% to 75% (e.g., 60%, 65%, or 70%).

[0027] In some embodiments, the light source module 220 may further include a light shielding layer 228. The light shielding layer 228 is superimposed on a surface 229 of the first reflective layer 224 facing away from the LED 222 and the light guide plate 210. In some embodiments, both the first reflective layer 224 and the light shielding layer 228 extend from the upper surface of the LED 222 (i.e., the continuous light-uniform surface 227 at the top in FIG. 2 ) to the upper surface 211 of the light guide plate 210, completely covering the air cavity S between the LED 222 and the light guide plate 210. In some embodiments, the light shielding layer 228 may completely overlap with the first reflective layer 224. Because the light shielding layer 228 is closer to the user than the first reflective layer 224, it can absorb or block various outgoing light rays in the peripheral area PA, thereby preventing them from affecting the user's visual experience. For example, the light shielding layer 228 can absorb or block light rays that directly pass through the first reflective layer 224.

[0028] Please first refer to Figure 2, which is a partial enlarged schematic diagram of region R1 in Figure 1. In some embodiments, the light source module 220 may further include a first optical adhesive layer 240. The first optical adhesive layer 240 is located between the first reflective layer 224 and the light guide plate 210. More specifically, it is located below the first reflective layer 224 and covers a portion of the upper surface 211 of the light guide plate 210 and the entire upper surface of the light-emitting diode 222 (i.e., the continuous light-homogenizing surface 227 at the top). In some embodiments, the first optical adhesive layer 240 may completely overlap with the light-shielding layer 228 and the first reflective layer 224. In other words, the first optical adhesive layer 240 may span the air cavity S between the light-emitting diode 222 and the light guide plate 210, forming a continuous covering layer thereon. In some embodiments, the side light incident surface 215 of the light guide plate 210, the light-emitting surface 223 of the light-emitting diode 222, the first optical adhesive layer 240, and the second reflective layer 226 collectively enclose the air cavity S. In some embodiments, the first optical adhesive layer 240, the first reflective layer 224, and the light-shielding layer 228 can be three layers of a single piece of black and white tape. For example, the first reflective layer 224 can be formed from a white polyethylene terephthalate (PET) substrate. Black ink is applied to one side of the white PET substrate to form the light-shielding layer 228, and a highly transparent adhesive is applied to the other side to form the first optical adhesive layer 240. These adhesives are readily available commercially, such as Sekisui Chemical Co., Ltd.'s product number 550P5 BSFX black and white tape. In some embodiments, the first optical adhesive layer 240 can be made of an acrylic adhesive having a light transmittance of 91% to 99.9% (e.g., 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%). In some embodiments, the thickness H2 of the first optical adhesive layer 240 may be 0.01 mm to 0.1 mm, preferably 0.03 mm to 0.065 mm (eg, 0.055 mm).

[0029] In some embodiments, the light source module 220 may further include a second optical adhesive layer 250. The second optical adhesive layer 250 is positioned between the second reflective layer 226 (flexible printed circuit board 230) and the light guide plate 210, such that the light guide plate 210 is disposed on the second reflective layer 226 (flexible printed circuit board 230) through the second optical adhesive layer 250. In some embodiments, the side surface 251 of the second optical adhesive layer 250 and the side light incident surface 215 of the light guide plate 210 may be on different planes. More specifically, the side surface 251 of the second optical adhesive layer 250 may be indented relative to the side light incident surface 215 of the light guide plate 210 (e.g., indented by approximately 0.1-0.3 microns). In some embodiments, the lower surface 253 of the second optical adhesive layer 250 may be substantially flush with the lower surface of the light-emitting diode 222 (i.e., the continuous light-homogenizing surface 227 at the bottom). In some embodiments, the side light incident surface 215 of the light guide plate 210, the light emitting surface 223 of the light-emitting diode 222, the first optical adhesive layer 240, the second optical adhesive layer 250, and the second reflective layer 226 collectively enclose an air cavity S. In some embodiments, the second optical adhesive layer 250 may be made of Nitto No. 5605 optical adhesive (available from Nitto Denko Corporation). In some embodiments, the material of the second optical adhesive layer 250 may be an acrylic adhesive having a light transmittance of 91% to 99.9% (e.g., 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%). In some embodiments, the thickness H3 of the second optical adhesive layer 250 may be 0.02 mm to 0.08 mm (e.g., 0.03 mm, 0.04 mm, 0.05 mm, 0.06 mm, or 0.07 mm).

[0030] It is worth noting that the first optical adhesive layer 240 and the second optical adhesive layer 250 can increase the light incident surface area of ​​the light guide plate 210. Specifically, because the first optical adhesive layer 240 and the second optical adhesive layer 250 have high light transmittance, which in some embodiments can even be higher than the light transmittance of the light guide plate 210, and the first optical adhesive layer 240 and the second optical adhesive layer 250 are respectively disposed on the upper surface 211 and the lower surface 213 of the light guide plate 210, the first optical adhesive layer 240 and the second optical adhesive layer 250 can be considered as extensions of the side light incident surface 215 of the light guide plate 210. Furthermore, the thickness H3 of the second optical adhesive layer 250 (0.05 mm to 0.15 mm) serves to elevate the light guide plate 210, aligning the side light incident surface 215 of the light guide plate 210 roughly with the center of the light-emitting surface 223 of the LED 222. This adjusts the angle of light entry and increases the proportion of light entering the light guide plate 210, thereby improving light utilization. Furthermore, by ensuring that the total thickness (H1 + H2 + H3) of the light guide plate 210, the first optical adhesive layer 240, and the second optical adhesive layer 250 is less than the thickness H4 of the LED 222, the light-emitting surface 223 of the LED 222 is significantly higher relative to the overall light incident surface. This design guides light emitted by the LED 222 into the light guide plate 210 in a "cohesive" manner, reducing light loss caused by light divergence.

[0031] Please return to Figure 1. In general, in the present disclosure, multiple light-emitting diodes 222, a first reflective layer 224, a second reflective layer 226, and the side light-entering surface 215 of the light guide plate 210 form a first light-mixing region A1. The provision of the first light-mixing region A1 allows light to undergo moderate reflection within the region A1, reducing its directivity and homogenizing it before entering the light guide plate 210. Specifically, the continuous light-homogenizing surface 227 (see Figure 2) within the light-emitting diode 222 promotes uniform diffusion of light during initial emission, reducing the occurrence of localized bright spots or dark areas. After this initial homogenization, the light enters the air cavity S. Some of the light enters the light guide plate 210 directly through the side light-entering surface 215, while another portion is first reflected and mixed by the first reflective layer 224 and the second reflective layer 226 for further homogenization. This homogenization mechanism is similar to the light processing mechanism within a photographic light box. Ultimately, the light adjusted by the first light mixing area A1 is evenly converged and enters the light guide plate 210, thereby improving the consistency and uniformity of the light. The present disclosure achieves the first light mixing mechanism through the provision of the first light mixing area A1. Specifically, because the light-emitting diode 222 of the present disclosure is taller than the light guide plate 210, the first reflective layer 224 extending from the light guide plate 210 to the light-emitting diode 222 has a slope Q at the position corresponding to the air cavity S. This slope Q gradually decreases from the light-emitting diode 222 to the light guide plate 210 (gradually approaching the second reflective layer 226), thereby helping the light to enter the light guide plate 210 in a "cohesive" manner, reducing light loss caused by light divergence.

[0032] Before describing the second light mixing mechanism, the touch module 140 and the reflective display module 150 of the present disclosure are first introduced.

[0033] Please continue to refer to Figure 1. The touch module 140 is located between the cover plate 110 and the front light module 200, and on the upper surface 211 of the light guide plate 210. It has a touch module side surface 141 facing the light source module 220. In some embodiments, the touch module 140 may include a sensing layer and control circuitry (not shown) to detect user touch operations and convert them into corresponding output signals. In some embodiments, to achieve signal transmission, the touch module 140 may be electrically connected to a driver circuit via a flexible printed circuit board 170, thereby stably transmitting touch data to the system control unit for further processing and execution of corresponding display or input commands.

[0034] The reflective display module 150 includes a reflective display 152 and a light shielding element 154. The reflective display module 150 is located on the lower surface 213 of the light guide plate 210 and between the light guide plate 210 and the housing 120. In other words, the light guide plate 210 is located between the touch module 140 and the reflective display module 150. The reflective display 152 has a display side surface 153 facing the light-emitting surface 223 of the light-emitting diode 222. The light shielding element 154 is connected to the reflective display 152, and the entire light source module 220 is located between the flexible printed circuit board 170 and the light shielding element 154. In some embodiments, the light shielding element 154 can be an opaque surface of the flexible printed circuit board 180, for example, made of a glossy black plastic material.

[0035] To accommodate the thinner design of the frontlight module 200 (i.e., a thinner light guide plate 210), the present disclosure further optimizes the structure of the light guide plate 210. Generally speaking, as the light guide plate 210 becomes thinner, its internal light mixing area is relatively reduced, potentially leading to a decrease in the uniformity of light before entering the viewing area VA, thereby affecting display quality. Therefore, unlike conventional frontlight modules where the edge of the light guide plate (e.g., the side-lighting surface) falls within the peripheral area of ​​the reflective display, the present disclosure further extends the length of the light guide plate 210 to a length greater than the entire length of the reflective display 152. More specifically, as shown in FIG. 1 , the light guide plate 210 extends beyond the outline dimension of the entire reflective display 152, that is, beyond the display side 153 of the entire reflective display 152. In other words, the vertical projection of the side incident surface 215 of the light guide plate 210 onto the cover plate 110 does not fall within the vertical projection of the reflective display 152 onto the cover plate 110. In other words, the vertical projection of the side incident surface 215 of the light guide plate 210 onto the cover plate 110 does not overlap with the vertical projection of the reflective display 152 onto the cover plate 110. By extending the light guide plate 210 beyond the display side 153 of the reflective display 152, even if the light guide plate 210 is thinner, more space for light mixing is provided. This allows the light from the light source module 220 to be fully uniformized before entering the viewing area VA, thereby reducing the occurrence of localized brightness unevenness or hot spots.

[0036] On the other hand, because the light-emitting surface 223 of the LED 222 and the side light-entering surface 215 of the light guide plate 210 face each other, the LED 222 of the present disclosure also extends beyond the entire display side 153 of the reflective display 152. In other words, the vertical projection of the reflective display 152 on the cover plate 110 does not overlap with the vertical projection of the LED 222 on the cover plate 110. Overall, the vertical projection of the side light-entering surface 215 of the light guide plate 210 on the cover plate 110 can be located between the vertical projection of the display side 153 of the reflective display 152 on the cover plate 110 and the vertical projection of the light-emitting surface 223 of the LED 222 on the cover plate 110.

[0037] Please refer to FIG. 3 for the relative positions of the light guide plate 210, the LED 222, the reflective display 152, and the touch module 140. The side light incident surface 215 of the light guide plate 210 serves as its dimensional boundary, the display side surface 153 of the reflective display 152 serves as its dimensional boundary, and the touch module side surface 141 of the touch module 140 serves as its dimensional boundary. In the present disclosure, the LED 222 is located outside the side light incident surface 215 of the light guide plate 210, and the side light incident surface 215 of the light guide plate 210 is located outside the display side surface 153 of the reflective display 152. Furthermore, the touch module side surface 141 of the touch module 140 may be located between the visible area boundary 151 of the reflective display 152 and the display side surface 153 of the reflective display 152, that is, within the peripheral area of ​​the reflective display 152.

[0038] In some embodiments, the horizontal distance d2 between the side light incident surface 215 of the light guide plate 210 and the display side surface 153 of the reflective display 152 may be 2.6 mm to 3.4 mm, and the horizontal distance d3 between the display side surface 153 of the reflective display 152 and the touch module side surface 141 of the touch module 140 may be 4.6 mm to 5.6 mm. In some embodiments, the horizontal distance d4 between the display side surface 153 of the reflective display 152 and the visible area boundary 151 of the reflective display 152 may be 16.54 mm to 17.14 mm.

[0039] Please return to Figure 2. Based on the aforementioned relative positional relationships between the light guide plate 210, LED 222, reflective display 152, and touch module 140, the light guide plate 210 of the present disclosure has an extension 210P outside the vertical projection of the touch module 140. This extension 210P has an exposed portion 210N that is not covered by the first reflective layer 224 or the second reflective layer 226, and this exposed portion 210N is exposed to air. Specifically, because the extension 210P of the light guide plate 210 has a portion that is not covered by any layer (e.g., a reflective layer, a light-shielding layer, or an optically transparent adhesive layer), this portion forms the exposed portion 210N that is directly in contact with air. It should be understood that while completely covering the extended portion 210P of the light guide plate 210 with a reflective layer or light-shielding layer may help improve the light efficiency of the light guide plate 210, it will cause light that enters the light guide plate 210 but does not meet the requirements for total internal reflection to propagate further within the light guide plate 210, further disrupting the light's direction of travel and thus affecting the final display quality. Therefore, the present disclosure exposes a portion of the extended portion 210P. This allows light that does not meet the requirements for total internal reflection to escape from the exposed portion 210N through the interface with air, reducing the disordered propagation of light within the light guide plate 210 and further improving the image display quality. Furthermore, the direct contact between the exposed portion 210N and air provides additional optical advantages. Specifically, due to the significant difference in refractive index between air (refractive index of 1) and light guide plate 210 (refractive index of approximately 1.6), the interface between air and light guide plate 210 increases the probability of light undergoing total internal reflection within light guide plate 210, allowing some light that meets the conditions for total internal reflection to continue to propagate within light guide plate 210, thereby improving light utilization efficiency. In some embodiments, the vertical projection of the display side surface 153 of the reflective display 152 onto the light guide plate 210 falls within the exposed portion 210N.

[0040] Please refer to Figures 1 and 2 together. Overall, the touch module side surface 141, ink layer 112, housing 120, and light shielding element 154 form a second light mixing area A2, and the extended portion 210P of the light guide plate 210 is located within the second light mixing area A2. Specifically, the upper boundary of the second light mixing area A2 is formed by the ink layer 112, the lower boundary is formed by the light shielding element 154, one side boundary is formed by the housing 120, and the other side boundary is at least partially formed by the touch module side surface 141. Furthermore, the boundaries of the second light mixing area A2 may also include the upper surface 211 and lower surface 213 of the light guide plate 210 on its extended portion 210P. In some embodiments, the touch display device 100 further includes an optical adhesive layer 190 disposed between the touch module 140 and the light guide plate 210, and between the light guide plate 210 and the reflective display 152. In this case, one side boundary of the second light mixing area A2 is formed by the touch module side surface 141 and the side surface 191 of the optical adhesive layer 190. In some embodiments, the light source module 220 (including the light-emitting diode 222, the first reflective layer 224, the second reflective layer 226, the light shielding layer 228, the first optical adhesive layer 240, and the second optical adhesive layer 250), the extension portion 210P of the light guide plate 210, and the flexible printed circuit board 170 are all located within the second light mixing area A2. Areas in the second light mixing area A2 without components are filled with air.

[0041] The ink layer 112 and the light-shielding element 154 are light-absorbing, effectively reducing the impact of stray light. The housing 120 is reflective, partially directing the direction of light propagation. Therefore, when light that doesn't meet the requirements for total internal reflection escapes from the exposed portion 210N of the extension 210P and enters the second light-mixing area A2, the majority of the light is absorbed by the ink layer 112 or the light-shielding element 154, preventing it from returning to the light guide plate 210 and causing light turbulence. A small amount of light may be reflected back to the light guide plate 210 via the housing 120. If the reflected light meets the requirements for total internal reflection, it can still be effectively utilized, avoiding additional light loss. This design prevents excessively turbulent light from re-entering the light guide plate 210, thereby improving light uniformity and achieving a more stable display effect. On the other hand, because the refractive index of the light guide plate 210 (approximately 1.6), the refractive index of the optical adhesive layer 190 (approximately 1.49), and the refractive index of the touch module 140 (approximately 1.6 for the touch substrate) are all higher than the refractive index of air (approximately 1), when light escapes from the light guide plate 210 to the second light mixing area A2 and attempts to re-enter these high-refractive-index media, if the incident angle of the light is small, the light will be transmitted closer to the normal direction of the material, allowing it to quickly penetrate the medium along a shorter path, thereby reducing interference with the light inside the light guide plate 210.

[0042] It is worth noting that after the light emitted by the LED 222 enters the light guide plate 210, some of the light fails to meet the total internal reflection requirement. If the light guide plate 210 does not extend into the second light mixing area A2, this light will easily form stray light on the side of the light guide plate 210 adjacent to the light incident surface 215, thereby affecting the image display quality and the user's visual experience. By designing the extension portion 210P of the light guide plate 210, the light guide plate 210 is able to extend into the second light mixing area A2. In this way, these light rays that do not meet the total internal reflection requirement can escape from the exposed portion 210N of the extension portion 210P into the second light mixing area A2 (air), avoiding re-entry into the light guide plate 210 and causing disturbance, thereby improving overall optical uniformity. Therefore, the light guide plate 210 needs to extend beyond the display side 153 of the reflective display 152 to form a sufficiently long extension portion 210P, thereby ensuring that the light guide plate 210 can extend into the second light mixing area A2. For example, if the length of the extension portion 210P is insufficient, it will be difficult to form an exposed portion 210N of sufficient length, resulting in the light that does not meet the total reflection conditions being unable to effectively escape to the second light mixing area A2 and remaining inside the light guide plate 210, resulting in a decrease in optical uniformity.

[0043] In particular, since the flexible printed circuit board 170 can be made of a translucent orange-brown plastic material, when the light emitting diode 222 is a white light emitting diode 222, the translucent orange-brown material of the flexible printed circuit board 170 can contribute to a color adjustment effect by enhancing the color temperature of the light emitted from the exposed portion 210N of the light guide plate 210 when it enters the second light mixing area A2 and passes through the flexible printed circuit board 170.

[0044] Please refer to Figure 2. In some embodiments, a plurality of optical microstructures 210M are disposed on the upper surface 211 or lower surface 213 of the light guide plate 210. The optical microstructures 210M are used to disrupt the total internal reflection of light within the light guide plate 210, allowing the light guide plate 210 to adjust and refract (guide) some light toward the reflective display 152. This allows the light reflected by the reflective display 152 to be refracted, allowing the user to view the image. In some embodiments, the exposed portion 210N of the light guide plate 210 is not provided with optical microstructures 210M on the upper surface 211 and lower surface 213. In other words, the exposed portion 210N on the upper surface 211 and lower surface 213 is substantially flat and directly exposed to air. Since the optical microstructures 210M are not arranged on the upper surface 211 and the lower surface 213 of the exposed portion 210N, interference of the optical microstructures 210M with the propagation direction of light can be avoided, and additional scattering of light in the exposed portion 210N is reduced, so that light that does not meet the total reflection conditions can smoothly enter the second light mixing area A2 (air) from the exposed portion 210N.

[0045] In some embodiments, the length L1 of the exposed portion 210N of the light guide plate 210 on the upper surface 211 is different from the length L2 of the exposed portion 210N on the lower surface 213 of the light guide plate 210. Specifically, the length L1 of the exposed portion 210N of the light guide plate 210 on the upper surface 211 may be smaller than the length L2 of the exposed portion 210N of the light guide plate 210 on the lower surface 213. In other words, the horizontal distance d5 between the inner sidewall 224I of the first reflective layer 224 and the side surface 191 of the optical adhesive layer 190 disposed on the upper surface 211 of the light guide plate 210 may be smaller than the horizontal distance d6 between the inner sidewall 226I of the second reflective layer 226 and the side surface 191 of the optical adhesive layer 190 disposed on the lower surface 213 of the light guide plate 210. This is because light escaping from above the light guide plate 210 is closer to the user. Therefore, compared to light escaping from light guide plate 210 away from the user, a more stringent light shielding arrangement is required above the light guide plate 210 to avoid affecting the user's viewing experience. In some embodiments, the difference between length L1 (horizontal distance d5) and length L2 (horizontal distance d6) can be 1.305 mm to 1.595 mm (e.g., 1.35 mm, 1.40 mm, 1.45 mm, 1.50 mm, or 1.55 mm).

[0046] Overall, the present disclosure implements a second light mixing mechanism through the provision of the second light mixing area A2, and achieves a dual light mixing mechanism by combining the first light mixing area A1 and the second light mixing area A2. Specifically, because the first light mixing area A1 is located within the second light mixing area A2, light that does not meet the total internal reflection conditions within the exposed portion 210N of the light guide plate 210 can also escape into the air cavity S within the first light mixing area A1 and into the space between the light-emitting diodes 222 (i.e., the spacing P shown in FIG. 3 ).

[0047] Please return to Figure 1. In some embodiments, the optical adhesive layer 190 of the touch display device 100 may include an optical adhesive layer 190a disposed between the upper surface 211 of the light guide plate 210 and the touch module 140, an optical adhesive layer 190b disposed between the lower surface 213 of the light guide plate 210 and the reflective display 152, and an optical adhesive layer 190c disposed between the cover plate 110 and the touch module 140. In some embodiments, to accommodate the thinner design of the touch display device 100, the thicknesses of the optical adhesive layers 190a, 190b, and 190c may be reduced. For example, the thickness T3 of the optical adhesive layer 190c and the thickness T1 of the optical adhesive layer 190a may each be 75 microns to 150 microns, while the thickness T2 of the optical adhesive layer 190b may be 50 microns to 100 microns. In some embodiments, the side surface 191 of the optical adhesive layer 190 (including the side surfaces of the optical adhesive layers 190 a , 190 b , and 190 c ) is flush with the side surface 141 of the touch module.

[0048] In some embodiments, the touch display device 100 may further include a support structure 300 and a direct surface attachment (DSA) structure 310. The direct surface attachment structure 310 can attach the touch module 140 to the support structure 300, and the support structure 300 can provide mechanical strength and stability. In some embodiments, the support structure 300 can also serve as part of the electrical connection. For example, the flexible printed circuit 170, 230 and the grounding wire 320 thereon can be connected to the support structure 300 to provide a stable electrical ground.

[0049] According to the above-mentioned embodiment of the present disclosure, by providing a dual light mixing area and extending the light guide plate and arranging the extended portion in the light mixing area, it can be ensured that the thinning of the light guide plate to meet the thin design of the touch display device will not affect the overall optical performance of the touch display device.

[0050] Although the present disclosure has been disclosed above in the form of implementation methods, it is not intended to limit the present disclosure. Anyone skilled in the art may make various changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the scope of protection of the present disclosure shall be determined by the scope of the attached patent application.

[0051] 100: Touch display device

[0052] 110: Cover

[0053] 111: Edge

[0054] 112: ink layer

[0055] 120: Shell

[0056] 121: Inner surface

[0057] 140: Touch module

[0058] 141: Touch module side

[0059] 150: Display module

[0060] 151: Boundary

[0061] 152: Reflective Display

[0062] 153: Side of the monitor

[0063] 154: Shading element

[0064] 160: Frame glue

[0065] 170: Flexible printed circuit board

[0066] 180: Flexible printed circuit board

[0067] 190,190a,190b,190c: Optical adhesive layer

[0068] 191: Side

[0069] 200: Front light module

[0070] 210: Light guide plate

[0071] 210P: Extension

[0072] 210N: Exposed part

[0073] 210M: Optical Microstructure

[0074] 211: Upper surface

[0075] 213: Lower surface

[0076] 215: Side light surface

[0077] 220: Light source module

[0078] 222: Light-emitting diode

[0079] 223: Luminous surface

[0080] 224: first reflective layer

[0081] 224I: inner wall

[0082] 225:Reflective surface

[0083] 227: Continuous uniform light surface

[0084] 226: Second reflective layer

[0085] 226I:Inner wall

[0086] 228:Light-shielding layer

[0087] 229: Surface

[0088] 230: Flexible printed circuit board

[0089] 240: first optical adhesive layer

[0090] 250: Second optical adhesive layer

[0091] 251: Side

[0092] 253: Lower surface

[0093] 300: Support structure

[0094] 310: Direct fit structure

[0095] 320: Ground wire

[0096] VA: visual area

[0097] PA: surrounding area

[0098] Y: Accommodation space

[0099] P: Spacing

[0100] S: air cavity

[0101] A1: The first mixed light area

[0102] A2: Second mixed light area

[0103] d1~d6: horizontal distance

[0104] H1~H4, T1~T3: thickness

[0105] L1~L2: Length

[0106] R1: Area

[0107] Q: Inclined surface

Claims

1. A touch display device, comprising: a cover plate having a visible area and a peripheral area, the peripheral area being provided with an ink layer; a housing, together with the cover plate, forming a housing; a front light module, comprising: a light guide plate having a light incident surface; and a light source module, comprising: a plurality of light-emitting diodes, each of the light-emitting diodes having a light-emitting surface facing the light incident surface, a reflective surface opposite the light-emitting surface, and a continuous light-uniforming surface surrounding the light-emitting surface and the reflective surface; a first reflective layer covering a portion of the light guide plate; and a second reflective layer supporting a portion of the light guide plate; a touch module located between the cover plate and the front light module and having a touch module side surface facing the light source module, wherein the light guide plate has an extension portion outside the vertical projection range of the touch module of the light guide plate, the extension portion having an exposed portion not covered by the first reflective layer and not covered by the second reflective layer, and the exposed portion is exposed to air; a reflective display module comprising: a reflective display, wherein the vertical projection of the reflective display on the cover plate does not overlap with the vertical projection of the light emitting diodes on the cover plate; and a light shielding element connected to the reflective display; wherein: The light-emitting diodes, the first reflective layer, the second reflective layer and the side light incident surface of the light guide plate form a first light mixing area; and the side surface of the touch module, the ink layer, the housing and the shading element form a second light mixing area, and the extended portion of the light guide plate is located in the second light mixing area.

2. The touch display device according to claim 1, wherein the light guide plate has an upper surface and a lower surface opposite to the upper surface, and the exposed portion is substantially flat on the upper surface and the lower surface and directly contacts the air.

3. The touch display device according to claim 1, wherein the light guide plate has an upper surface and a lower surface opposite to the upper surface, and a length of the exposed portion on the upper surface is shorter than a length of the exposed portion on the lower surface.

4. The touch display device according to claim 1, wherein the continuous light-homogenizing surface is a light-transmitting matte surface.

5. The touch display device of claim 1, wherein the front light module further comprises a first optical adhesive layer and a second optical adhesive layer, the first optical adhesive layer being located between the first reflective layer and the light guide plate, the second optical adhesive layer being located between the second reflective layer and the light guide plate, and the total thickness of the light guide plate, the first optical adhesive layer, and the second optical adhesive layer being less than the thickness of each of the light-emitting diodes.

6. The touch display device according to claim 5, wherein a lower surface of the second optical adhesive layer is flush with a lower surface of each of the light emitting diodes.

7. The touch display device according to claim 5, wherein the light transmittance of the first optical adhesive layer and the second optical adhesive layer is 91% to 99.9%.

8. The touch display device according to claim 1, wherein a vertical projection of the side light incident surface of the light guide plate on the cover plate does not overlap with a vertical projection of the reflective display on the cover plate.

9. The touch display device according to claim 1, wherein the reflective display has a display side surface facing the light-emitting surface of each of the light-emitting diodes, and a vertical projection of the display side surface on the light guide plate falls within the exposed portion.

10. The touch display device according to claim 1, wherein the first reflective layer, the second reflective layer, the side light incident surface of the light guide plate, and the light emitting surface of each of the light emitting diodes enclose an air cavity, and the first reflective layer has a slope at a position corresponding to the air cavity.

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