Touch display device

Abstract

The touch display device includes a cover plate, a housing, 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 surface facing the light source module. The light guide plate has an extension outside the vertical projection range of the touch module on the light guide plate. The extension has an exposed portion which is not covered and exposed to air. The reflective display module includes a reflective display and a light shielding element. The reflective display and the light emitting diode do not overlap in the vertical projection on the cover plate. The light emitting diode, the first and second reflective layers and the side light entrance 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 light shielding element form a second light mixing area. The extension is located in the second light mixing area. The disclosure can ensure that the thinning of the light guide plate in response to the thin design of the touch display device will not affect the overall optical performance of the touch display device.

Description

Technical Field

[0001] This disclosure relates to a touch display device, and more particularly to a reflective touch display device. Background Technology

[0002] E-book readers utilize bistable display technology, consuming power only when changing screens. Compared to conventional self-emissive displays, this reduces power consumption by over 90%, achieving energy-saving and environmentally friendly results. Furthermore, replacing traditional paper books with e-books reduces carbon emissions caused by deforestation, demonstrating sustainability through green technology.

[0003] Generally, reflective display devices often incorporate a front light guide plate to provide display functionality in dark or low-light conditions. However, this can hinder the achievement of thinner design requirements when integrating a touch panel to form a touch display device. Existing technologies address this by reducing the thickness of the light guide plate. However, a thinner light guide plate can easily lead to other problems, causing optical defects in the touch display device, such as hotspots.

[0004] To address the optical issues caused by the thinning of the light guide plate, prior art (Taiwanese patent number TWI855599) proposed several solutions. For example, by placing a light-shielding film on top of the light-emitting element and the light guide plate, and configuring a flexible circuit board at the bottom, the optical performance of the thinner light guide plate was improved. Furthermore, the light coupling efficiency was enhanced through the ratio design of the light-emitting element to the thickness of the light guide plate. However, this prior art, by covering the light-emitting element with a light-shielding film, causes some light absorption, resulting in a decrease in overall light utilization efficiency. In addition, this prior art did not further consider the changes in light mixing effects after the light guide plate thickness was reduced, leading to poor light uniformity at the end of the light guide plate near the light source, potentially causing localized hot spots (spots) or uneven light emission. Therefore, balancing the thin design of touch display devices with light uniformity is a direction worthy of current research. Summary of the Invention

[0005] According to some embodiments disclosed herein, a touch display device includes a cover plate, a housing, a front light module, a touch module, and a reflective display module. The cover plate has a visible area and a peripheral area, the peripheral area being provided with an ink layer. The housing and the cover plate together form an accommodating space. The front light module includes a light guide plate and a light source module. The light guide plate has a side-incident light surface. The light source module includes a plurality of light-emitting diodes (LEDs), a first reflective layer, and a second reflective layer. Each LED has a light-emitting surface facing the side-incident light surface, a reflective surface opposite the light-emitting surface, and a continuous uniform light surface surrounding the light-emitting and reflective surfaces. 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 front light module and has a side facing the light source module. The light guide plate has an extension beyond the vertical projection range of the touch module onto the light guide plate, the extension having exposed portions not covered by the first reflective layer and not covered by the second reflective layer, and the exposed portions are exposed to air. The reflective display module includes a reflective display and a light-shielding element. The vertical projection of the reflective display onto the cover plate does not overlap with the vertical projection of the light-emitting diode onto the cover plate. A light-shielding 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 of the touch module, the ink layer, the housing, and the light-shielding element form a second light-mixing area, and the extension of the light guide plate is located in the second light-mixing area.

[0006] In some embodiments disclosed herein, the light guide plate has an upper surface and a lower surface relative to the upper surface, and the exposed portion is a substantially flat surface on both the upper and lower surfaces and is in direct contact with the air.

[0007] In some embodiments disclosed herein, the light guide plate has an upper surface and a lower surface relative to the upper surface, and the length of the exposed portion on the upper surface is less than the length of the exposed portion on the lower surface.

[0008] In some embodiments disclosed herein, the continuous uniform light surface is a translucent matte surface.

[0009] In some embodiments disclosed herein, the front light module further includes a first optical adhesive layer and a second optical adhesive layer. 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. 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 disclosed herein, the lower surface of the second optical adhesive layer is flush with the lower surface of each light-emitting diode.

[0011] In some embodiments disclosed herein, the light transmittance of the first optical adhesive layer and the second optical adhesive layer is 91% to 99.9% respectively.

[0012] In some embodiments disclosed herein, the vertical projection of the side-incident surface of the light guide plate onto the cover plate does not overlap with the vertical projection of the reflective display onto the cover plate.

[0013] In some embodiments disclosed herein, the reflective display has a display side facing the light-emitting surface of each light-emitting diode, and the vertical projection of the display side onto the light guide plate falls in the exposed portion.

[0014] In some embodiments disclosed herein, 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 surround an air cavity, and the first reflective layer has an inclined surface at the position corresponding to the air cavity.

[0015] According to the above-described embodiments disclosed herein, by setting up dual light mixing zones and extending the light guide plate, and placing the extended portion in the light mixing zone, it can be ensured that reducing the thickness of the light guide plate to accommodate the thinner design of the touch display device will not affect the overall optical performance of the touch display device. Attached Figure Description

[0016] To make the above and other objects, features, advantages and embodiments disclosed herein more apparent and understandable, the accompanying drawings are described below:

[0017] Figure 1 This is a cross-sectional schematic diagram of a touch display device according to some embodiments disclosed herein;

[0018] Figure 2 for Figure 1 A magnified view of a portion of region R1 in the middle; and

[0019] Figure 3 This is a top view schematic diagram of some components in a touch display device according to some embodiments of the present disclosure.

[0020] [Symbol Explanation]

[0021] 100: Touch display device

[0022] 110: Cover plate

[0023] 111: Edge

[0024] 112: Ink layer

[0025] 120: Casing

[0026] 121: Inner surface

[0027] 140: Touch module

[0028] 141: Side of the touch module

[0029] 150: Display Module

[0030] 151: Boundary

[0031] 152: Reflective Display

[0032] 153: Side of the monitor

[0033] 154: Light-shielding element

[0034] 160: Frame adhesive

[0035] 170: Flexible Circuit Board

[0036] 180: Flexible Circuit Board

[0037] 190, 190a, 190b, 190c: Optical adhesive layer

[0038] 191: Side View

[0039] 200: Front optical module

[0040] 210: Light guide plate

[0041] 210P: Extension

[0042] 210N: Exposed parts

[0043] 210M: Optical Microstructure

[0044] 211: Upper surface

[0045] 213: Lower surface

[0046] 215: Side-entry light surface

[0047] 220: Light source module

[0048] 222: Light Emitting Diode

[0049] 223: Luminous Surface

[0050] 224: First reflective layer

[0051] 224I: Inner wall

[0052] 225: Reflective surface

[0053] 227: Continuous uniform surface

[0054] 226: Second reflective layer

[0055] 226I: Inner wall

[0056] 228: Light-shielding layer

[0057] 229: Surface

[0058] 230: Flexible Circuit Board

[0059] 240: First optical adhesive layer

[0060] 250: Second optical adhesive layer

[0061] 251: Side view

[0062] 253: Lower surface

[0063] 300: Supporting structure

[0064] 310: Direct bonding structure

[0065] 320: Grounding wire

[0066] VA: Visible Area

[0067] PA: Surrounding Area

[0068] Y: Accommodation space

[0069] P: Spacing

[0070] S: Air cavity

[0071] A1: First Mixed Light Zone

[0072] A2: Second Mixing Zone

[0073] d1~d6: Horizontal distance

[0074] H1~H4, T1~T3: Thickness

[0075] L1~L2: Length

[0076] R1: Region

[0077] Q: Inclined surface Detailed Implementation

[0078] The following describes several embodiments of this disclosure with reference to the accompanying drawings. For clarity, many practical details will be described in the following description. However, these practical details are not intended to limit the disclosure. Additionally, 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 between one element and another, as shown in the drawings. It should be understood that relative terms are intended to encompass different orientations of the device other than those shown in the figures. Furthermore, terms such as "first" and "second" used in the specification or claims are used only to name different elements or distinguish different embodiments or scopes, and are not intended to limit the upper or lower limit of the number of elements, nor to limit the manufacturing or installation order of the elements.

[0079] Please see Figure 1This is a cross-sectional schematic diagram 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 disclosed herein is a reflective touch display device. In the following description, each of the above-mentioned components will be described in detail.

[0080] Cover plate 110 has a visible area VA and a peripheral area PA, and the peripheral area PA of cover plate 110 facing touch module 140 is provided with an ink layer 112 for preventing light leakage. In some embodiments, ink layer 112 may extend from edge 111 of cover plate 110 toward visible area VA, so that peripheral area PA and visible area VA have a boundary. In some embodiments, ink layer 112 may comprise three stacked layers, of which one black ink layer is located on the side relatively closer to touch module 140, and two white ink layers are located on the side relatively closer to cover plate 110. In some embodiments, the material of cover plate 110 has a certain degree of rigidity, such as glass, quartz, or a suitable polymer (e.g., polycarbonate, polymethyl methacrylate) to provide protection for touch display device 100.

[0081] The housing 120 and the cover plate 110 together form an accommodating space Y, and the front light module 200, the touch module 140, and the reflective display module 150 are all located in this accommodating space Y. In some embodiments, the housing 120 and the cover plate 110 together enclose a cuboid accommodating space Y. In some embodiments, the housing 120 can be attached to the cover plate 110 by means of frame adhesive 160 disposed in the peripheral area PA of the cover plate 110. In some embodiments, the material of the inner surface 121 of the housing 120 can be stainless steel, which has the characteristic of reflecting light; that is, the inner surface 121 of the housing 120 can be a reflective surface.

[0082] A front light module 200 is configured to provide front illumination for a touch display device 100 and includes a light guide plate 210 and a light source module 220. The light source module 220 provides light to the light guide plate 210 and works in conjunction 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-incident surface 215, wherein the upper surface 211 is opposite to the lower surface 213, and the side-incident surface 215 connects the upper surface 211 and the lower surface 213 and faces the light-emitting diode 222 in the light source module 220. In other words, the light emitted by the light-emitting diode 222 enters the light guide plate 210 in the form of side-incident light. In some embodiments, the light guide plate 210 may comprise polycarbonate, polymethacrylate, polyolefin, or combinations thereof, and is preferably designed to be flexible.

[0083] To accommodate the thinner design of the front light module 200, the thickness H1 of the light guide plate 210 disclosed herein can be designed to be 0.1 mm to 0.25 mm (e.g., 0.15 mm, 0.20 mm). However, while thinning the light guide plate 210 helps to achieve a thinner design for the front light module 200, it can also lead to other problems and optical defects in the front light module 200. For example, the reduced optical path length of the thinner light guide plate 210 results in a smaller light mixing space, which may cause uneven light distribution (i.e., hot spot problems). In response, this disclosure not only thins the light guide plate 210 to accommodate the thinner design of the front light module 200, but also improves the uneven light distribution problem caused by the thinning of the light guide plate 210 through at least a dual light mixing mechanism, thereby ensuring the overall applicability of the touch display device 100. Detailed embodiments will be described later.

[0084] 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-incident surface 215 of the light guide plate 210. Furthermore, each light-emitting diode 222 also has a reflective surface 225 opposite to the light-emitting surface 223 (see [link to relevant documentation]). Figure 2 ) and a continuous uniform light surface 227 surrounding the emitting surface 223 and the reflecting surface 225 (see also Figure 2 In some embodiments, the continuous light-diffusing surface 227 may be a translucent frosted surface, such as a frosted surface or a translucent material with a microstructure. In some embodiments, the continuous light-diffusing surface 227 may be made of a material with partial light transmittance and high haze, such as a translucent milky white soft-fuzzy heat-resistant polymer. In some embodiments, the light source module 220 may include a housing (e.g., an encapsulation housing) that completely covers the light-emitting diode 222, and the continuous light-diffusing surface 227 of the light-emitting diode 222 may be made of the material of this housing. That is, the light does not only pass through a two-dimensional translucent frosted surface, but also through a translucent frosted surface structure with a certain thickness (e.g., the thickness of one side of the housing). When the continuous light-diffusing surface 227 is a translucent frosted surface, it can diffuse the light that is not directly emitted from the light-emitting surface 223, thereby reducing local overbrightness or light spots (hot spots). In contrast, parabolic reflector lampshades are commonly used. When the continuous uniform light surface 227 is a non-transparent reflective surface, the light that is not directly emitted from the light-emitting surface 223 will converge and concentrate after being reflected by the reflective surface. Although this improves the light efficiency, it will cause the light entering the light guide plate 210 to be excessively concentrated, resulting in uneven brightness distribution.

[0085] In some embodiments, the light-emitting diode 222 may have an elongated light-emitting surface 223, such as a rectangular light-emitting surface 223. Compared to a point light source, the elongated light-emitting surface 223 can reduce light diffraction and provide a more uniform light distribution. Furthermore, by elongating the light-emitting surface 223 and extending it horizontally, combined with a continuous light-diffusing surface 227 made of a translucent, soft-matrix material, the pitch between adjacent light-emitting diodes 222 can be effectively blurred, reducing the obvious bright-dark boundary caused by the light source arrangement and the hot spots caused by optical interference due to the regular spacing of point light sources, thereby improving the overall optical uniformity. In some embodiments, the light-emitting diode 222 is selected from the SSWM31CQ2-NAA model (purchased from Seoul Semiconductor), with dimensions of 3.0 mm (width) × 0.85 mm (length) × 0.3 mm (thickness H4, see [link]). Figure 2 ).

[0086] Please also refer to Figure 1 and Figure 3 ,in Figure 3This is a top view schematic diagram of some components in a touch display device 100 according to some embodiments of the present disclosure. In some embodiments, a plurality of light-emitting diodes 222 are arranged at intervals on the second reflective layer 226 along the side light-incident surface 215 of the light guide plate 210, and the spacing 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, 14.5 mm), where the spacing 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 light-incident surface 215 of the light guide plate 210 can be 0.1275 mm to 0.850 mm. By setting such a horizontal distance d1, light can propagate in the air before entering the light guide plate 210 to diffuse appropriately. This also allows the light-emitting surface 223 of the LED 222 to be at a similar distance from the first reflective layer 224, the second reflective layer 226, and the side-incident light 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 and avoiding localized over-brightness or the formation of light-dark boundaries. If the horizontal distance d1 is too small, the light may be too concentrated in localized areas, resulting in uneven brightness and potentially causing excessively strong localized bright spots (hot spots) due to light diffraction. If the horizontal distance d1 is too large, some light may have already diffused excessively before entering the light guide plate 210, potentially causing light to escape beyond the side-incident light surface 215, leading to undesirable light emission and reducing the amount of light entering the light guide plate 210, thus lowering the overall illumination brightness. In some implementations, the lower limit of the horizontal distance d1 can be calculated as follows: (thickness H1 of light guide plate 210 + thickness H2 of first optical adhesive layer 240 + thickness H3 of second optical adhesive layer 250) / 2. This design takes into account the distance between the light source (LED 222) and each reflector, so that the amount of light reflected back in different directions is similar, avoiding excessive concentration of reflected light in a single direction, thereby improving the uniformity of light distribution.

[0087] Please return Figure 1 The first reflective layer 224 covers the upper surface 211 of the light guide plate 210, and the second reflective layer 226 supports 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., Figure 2 A continuous uniform light-emitting surface 227 at the top center covers the entire light-emitting diode 222, and a second reflective layer 226 further extends to the lower surface of the light-emitting diode 222 (i.e., Figure 2The continuous uniform light surface 227 at the bottom of the light guide plate 210 supports the light-emitting diode 222 on the whole surface. In 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 together enclose the air cavity S. The arrangement of the first reflective layer 224 and the second reflective layer 226 can constrain the reflection direction of light, allowing the light to enter the air cavity S after leaving the light-emitting surface 223. Within the air cavity S, the light direction is adjusted by reflection from the first reflective layer 224 and the second reflective layer 226 before entering the light guide plate 210. This mechanism reduces the directivity of the highly directional light emitted by the LEDs 222 through reflection by the surrounding structure of the air cavity S (i.e., increases the scattering of the light entering the light guide plate 210 through reflection). This homogenization process occurs before the light travels through the light guide plate 210, resulting in a more uniform distribution of light traveling within the light guide plate 210, 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., ...). Figure 3 (as shown at spacing P). In some embodiments, the second reflective layer 226 may be an opaque reflective surface of the flexible circuit board 230 connected to the light-emitting diode 222, for example... Figure 2 An opaque reflective surface is located above the flexible circuit board 230. In some embodiments, the second reflective layer 226 may be an ink-coated film, a chemically plated film, or an electroplated film, or the white surface of the flexible circuit board 230 itself (i.e., providing reflectivity by selecting a white flexible 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%).

[0088] In some embodiments, the light source module 220 may further include a light-shielding layer 228. The light-shielding layer 228 is stacked on the surface 229 of the first reflective layer 224 opposite to the light-emitting diode 222 and the light guide plate 210. In some embodiments, both the first reflective layer 224 and the light-shielding layer 228 are formed by the upper surface of the light-emitting diode 222 (i.e., Figure 2The continuous uniform light-emitting surface 227 at the top extends to the upper surface 211 of the light guide plate 210 and completely covers the air cavity S between the light-emitting diode 222 and the light guide plate 210. In some embodiments, the light-shielding layer 228 may completely overlap with the first reflective layer 224. Since the light-shielding layer 228 is closer to the user than the first reflective layer 224, it can absorb or block various outwardly emitted light rays present in the peripheral area PA, avoiding affecting the user's visual experience. For example, the light-shielding layer 228 can absorb or block light rays that directly penetrate the first reflective layer 224.

[0089] Please refer to the following first. Figure 2 , it is Figure 1 A partially enlarged schematic diagram of region R1. 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, and more specifically, it is located below the first reflective layer 224 and covers part 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 uniform light 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, that is, the first optical adhesive layer 240 may span the air cavity S between the light-emitting diode 222 and the light guide plate 210 and form 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 together 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 may be three layers in a single piece of black and white adhesive tape. For example, the first reflective layer 224 may be composed of a white polyethylene terephthalate (PET) substrate, with black ink coated on one side of the white PET substrate to form the light-shielding layer 228, and a light-transmitting adhesive coated on the other side to form the first optical adhesive layer 240. These materials are readily available from commercially available products, such as the black and white adhesive tape model 550P5 BSFX from Sekisui Chemicals Co., Ltd. In some embodiments, the material of the first optical adhesive layer 240 may be an acrylic adhesive, which may have a light transmittance of 91% to 99.9% (e.g., 92%, 93%, 94%, 95%, 96%, 97%, 98%, 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 (e.g., 0.055 mm).

[0090] In some embodiments, the light source module 220 may further include a second optical adhesive layer 250. The second optical adhesive layer 250 is located between the second reflective layer 226 (flexible 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 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 recessed within the side light-incident surface 215 of the light guide plate 210 (e.g., recessed by about 0.1 to 0.3 micrometers). 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 bottom continuous uniform light surface 227). In some embodiments, the side-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 together enclose the air cavity S. In some embodiments, the second optical adhesive layer 250 may be an optical adhesive with product model number Nitto No. 5605 (purchased from Nitto Denko Corporation). In some embodiments, the material of the second optical adhesive layer 250 may be an acrylic adhesive, which may have 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).

[0091] 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, since the first optical adhesive layer 240 and the second optical adhesive layer 250 have high light transmittance, and in some embodiments even 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 regarded 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, ensuring that the side light-incident surface 215 of the light guide plate 210 is approximately aligned with the center of the light-emitting surface 223 of the LED 222. This adjusts the incident light angle, increasing the proportion of light entering the light guide plate 210, thus improving light utilization. In addition, 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, a greater height of the light-emitting surface 223 of the LED 222 relative to the entire incident light surface is ensured. This design guides the light emitted by the LED 222 to converge into the light guide plate 210 in a "cohesive" manner, reducing light loss caused by light divergence.

[0092] Please return Figure 1 Overall, in this disclosure, multiple light-emitting diodes 222, a first reflective layer 224, a second reflective layer 226, and a side-incident light surface 215 of the light guide plate 210 form a first light-mixing region A1. Through the arrangement of the first light-mixing region A1, light can undergo moderate reflection within the first light-mixing region A1 to reduce its directivity, thus homogenizing it before entering the light guide plate 210. Specifically, the continuous light-migrating surface 227 within the light-emitting diodes 222 (see...) Figure 2This allows light to diffuse uniformly from the initial emission, reducing the generation of localized bright or dark areas. The pre-homogenized light then enters the air cavity S. Part of the light enters the light guide plate 210 directly via the side-incident surface 215, while the other part is 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 in a photographic light box. Finally, the light adjusted by the first mixing zone A1 is uniformly converged and enters the light guide plate 210, thereby improving the consistency and uniformity of the light. This disclosure achieves the first mixing mechanism through the setting of the first mixing zone A1. In particular, since the light-emitting diode 222 disclosed herein is higher than the light guide plate 210, the first reflective layer 224 extending from the light guide plate 210 to the light-emitting diode 222 will have 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 concentrate into the light guide plate 210 in a "cohesive" manner and reducing the light loss caused by light divergence.

[0093] Before explaining the second light mixing mechanism, the touch module 140 and reflective display module 150 disclosed herein will be introduced.

[0094] Please continue reading. Figure 1 The touch module 140 is located between the cover plate 110 and the front light module 200, and is situated on the upper surface 211 of the light guide plate 210, with a touch module side 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 can be electrically connected to the driving circuitry via a flexible circuit board 170 to stably transmit touch data to the system control unit for further processing and execution of corresponding display or input commands.

[0095] 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 side of the lower surface 213 of the light guide plate 210 and between the light guide plate 210 and the housing 120; that is, 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 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 circuit board 170 and the light-shielding element 154. In some embodiments, the light-shielding element 154 may be an opaque surface of the flexible circuit board 180, and may be, for example, a smooth, glossy black plastic material.

[0096] To accommodate the thinner design of the front light module 200 (i.e., the thinner light guide plate 210 design), this disclosure further optimizes the structure of the light guide plate 210. Generally, when the light guide plate 210 is thinner, its internal light mixing area is relatively reduced, which may lead to a decrease in the uniformity of light before it enters the visible area VA, thus affecting display quality. Therefore, unlike in typical front light modules where the edge of the light guide plate (e.g., the side-incident surface) falls within the peripheral area of ​​the reflective display, this disclosure further extends the length of the light guide plate 210 to be greater than the length of the entire reflective display 152. More specifically, as... Figure 1 As shown, 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 light-incident surface 215 of the light guide plate 210 onto the cover plate 110 does not fall within the vertical projection range of the reflective display 152 onto the cover plate 110; that is, the vertical projection of the side light-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 becomes thinner, more light mixing space can still be provided, allowing the light from the light source module 220 to be sufficiently homogenized before entering the visible area VA, thereby reducing the generation of local brightness unevenness or hot spots.

[0097] On the other hand, since the light-emitting surface 223 of the LED 222 and the side-incident surface 215 of the light guide plate 210 are facing each other, the LED 222 disclosed herein also extends beyond the entire display side 153 of the reflective display 152. That is to say, the vertical projection of the reflective display 152 onto the cover plate 110 and the vertical projection of the LED 222 onto the cover plate 110 do not overlap. Overall, the vertical projection of the side-incident surface 215 of the light guide plate 210 onto the cover plate 110 can be located between the vertical projection of the display side 153 of the reflective display 152 onto the cover plate 110 and the vertical projection of the light-emitting surface 223 of the LED 222 onto the cover plate 110.

[0098] For the relative positions of the light guide plate 210, the light-emitting diode 222, the reflective display 152, and the touch module 140, please refer to [link / reference]. Figure 3The side-incident surface 215 of the light guide plate 210 is its dimensional boundary, the display side 153 of the reflective display 152 is its dimensional boundary, and the touch module side 141 of the touch module 140 is its dimensional boundary. In this disclosure, the light-emitting diode 222 is located outside the side-incident surface 215 of the light guide plate 210, and the side-incident surface 215 of the light guide plate 210 is located outside the display side 153 of the reflective display 152. Furthermore, the touch module side 141 of the touch module 140 may be located between the visible area boundary 151 of the reflective display 152 and the display side 153 of the reflective display 152, that is, located in the peripheral area of ​​the reflective display 152.

[0099] In some embodiments, the horizontal distance d2 between the side light-incident surface 215 of the light guide plate 210 and the display side 153 of the reflective display 152 can be 2.6 mm to 3.4 mm, and the horizontal distance d3 between the display side 153 of the reflective display 152 and the touch module side 141 of the touch module 140 can be 4.6 mm to 5.6 mm. In some embodiments, the horizontal distance d4 between the display side 153 of the reflective display 152 and the viewable area boundary 151 of the reflective display 152 can be 16.54 mm to 17.14 mm.

[0100] Please return Figure 2Based on the relative positional relationship between the light guide plate 210, the light-emitting diode 222, the reflective display 152, and the touch module 140, the light guide plate 210 disclosed herein has an extension 210P outside the vertical projection range of the touch module 140. This extension 210P has an exposed portion 210N that is not covered by the first reflective layer 224 and the second reflective layer 226, and this exposed portion 210N is exposed to the air. In detail, since 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 can form an exposed portion 210N that is in direct contact with the air. It should be understood that if the extension 210P of the light guide plate 210 is completely covered by a reflective layer or a light-shielding layer, although this may help improve the light efficiency of the light guide plate 210, it will cause light entering the light guide plate 210 that does not meet the condition of total internal reflection to propagate further within the light guide plate 210, resulting in a more chaotic light travel direction and thus affecting the final display effect. Therefore, this disclosure exposes a portion of the extension 210P, allowing light that does not meet the condition of 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 effect. In addition, the direct contact between the exposed portion 210N and the air provides additional optical advantages. In detail, due to the significant difference in refractive index between air (refractive index 1) and the light guide plate 210 (refractive index approximately 1.6), the interface between air and the light guide plate 210 increases the probability of total internal reflection of light within the light guide plate 210. This allows some light that meets the conditions for total internal reflection to continue propagating within the light guide plate 210, thereby improving light utilization efficiency. In some embodiments, the vertical projection of the display side 153 of the reflective display 152 onto the light guide plate 210 falls in the exposed portion 210N.

[0101] Please also refer to Figure 1 and Figure 2Overall, the touch module side 141, ink layer 112, housing 120, and light-shielding element 154 form a second light-mixing area A2, and the extension 210P of the light guide plate 210 is located in 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 141. Further, the boundary of the second light-mixing area A2 may also include the upper surface 211 and lower surface 213 of the light guide plate 210 in its extension 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 region A2 is formed by the side 141 of the touch module and the side 191 of the optical adhesive layer 190. In some embodiments, the light source module 220 (including a light-emitting diode 222, a first reflective layer 224, a second reflective layer 226, a light-shielding layer 228, a first optical adhesive layer 240, and a second optical adhesive layer 250), the extension 210P of the light guide plate 210, and the flexible circuit board 170 are all located inside the second light mixing region A2, and the areas in the second light mixing region A2 without components are filled with air.

[0102] The ink layer 112 and the light-shielding element 154 are light-absorbing, effectively reducing the influence of stray light, while the housing 120 is reflective, partially guiding the direction of light propagation. Therefore, when light that does not meet the conditions for total internal reflection escapes from the exposed portion 210N of the extension 210P into the second light mixing zone A2, most of the light will be 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 disturbance. A small portion of the light may be reflected back to the light guide plate 210 through the housing 120, and if the reflected light meets the conditions for total internal reflection, it can still be effectively utilized, avoiding additional light loss. This design prevents excessive disturbed light from re-entering the light guide plate 210, thereby improving the uniformity of light and making the display effect more stable. On the other hand, since 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 (the touch substrate is approximately 1.6) 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, if it 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 and reducing interference with the light inside the light guide plate 210.

[0103] 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 condition. If the light guide plate 210 does not extend into the second light mixing zone A2, these rays can easily form stray light on the side of the light-incident surface 215 adjacent to the light guide plate 210, thereby affecting the image display effect and the user's visual experience. Through the design of the extension portion 210P of the light guide plate 210, the light guide plate 210 can extend into the second light mixing zone A2. In this way, these rays that do not meet the total internal reflection condition can escape from the exposed portion 210N of the extension portion 210P into the second light mixing zone A2 (air), avoiding re-entry into the interior of the light guide plate 210 and causing chaos, thus improving the overall optical uniformity. Based on this, 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 zone A2. For example, if the length of the extension 210P is insufficient, it will be difficult to form a sufficiently long exposed portion 210N, causing light that does not meet the total internal reflection condition to be unable to effectively diffuse into the second light mixing zone A2, but to remain inside the light guide plate 210, resulting in a decrease in optical uniformity.

[0104] In particular, since the flexible circuit board 170 can be made of a semi-transparent orange-brown plastic material, when the light-emitting diode 222 is a white light-emitting diode 222, when the light emitted from the exposed part 210N of the light guide plate 210 enters the second light mixing zone A2 and passes through the flexible circuit board 170, the semi-transparent orange-brown material of the flexible circuit board 170 can contribute to the color temperature adjustment effect of the transmitted light.

[0105] Please refer to the following first. Figure 2 In some embodiments, a plurality of optical microstructures 210M are arranged on the upper surface 211 or the lower surface 213 of the light guide plate 210. The optical microstructures 210M are used to disrupt the total internal reflection phenomenon of light in the light guide plate 210, so that the light guide plate 210 can adjust to refract (guide) part of the light to the reflective display 152, and then refract the light reflected by the reflective display 152 so that the user can view the image. In some embodiments, the exposed portion 210N of the light guide plate 210 does not have optical microstructures 210M arranged on the upper surface 211 and the lower surface 213. That is to say, the exposed portion 210N has substantially flat surfaces on the upper surface 211 and the lower surface 213, and these surfaces are in direct contact with the air. Since the upper surface 211 and lower surface 213 of the exposed portion 210N are not equipped with optical microstructures 210M, the interference of optical microstructures 210M on the direction of light propagation can be avoided, and the additional scattering of light in the exposed portion 210N can be reduced, so that light that does not meet the condition of total internal reflection can smoothly enter the second mixing zone A2 (air) from the exposed portion 210N.

[0106] 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 of the light guide plate 210 on the lower surface 213. Specifically, the length L1 of the exposed portion 210N of the light guide plate 210 on the upper surface 211 can be less than the length L2 of the exposed portion 210N of the light guide plate 210 on the lower surface 213. That is, 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 can be less 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 the light escaping from above the light guide plate 210 is closer to the user, therefore a more stringent light-blocking arrangement is needed above the light guide plate 210 compared to directions farther from the user, 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 from 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).

[0107] Overall, this disclosure achieves a second light mixing mechanism by setting a second light mixing region A2, and a dual light mixing mechanism by combining the first light mixing region A1 and the second light mixing region A2. Specifically, since the first light mixing region A1 is located within the second light mixing region A2, light rays in the exposed portion 210N of the light guide plate 210 that do not meet the total internal reflection condition can also escape into the air cavity S within the first light mixing region A1 and the space between the light-emitting diodes 222 (i.e., Figure 3 At the distance P shown.

[0108] Please return 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 from 75 micrometers to 150 micrometers, while the thickness T2 of the optical adhesive layer 190b may be from 50 micrometers to 100 micrometers. In some embodiments, the side 191 of the optical adhesive layer 190 (including the side of each of the optical adhesive layers 190a, 190b, and 190c) is flush with the side 141 of the touch module.

[0109] In some embodiments, the touch display device 100 may further include a support structure 300 and a direct surface attachment (DSA) structure 310, wherein the DSA structure 310 can attach the touch module 140 to the support structure 300, and the support structure 300 provides mechanical strength and stability. In some embodiments, the support structure 300 may also serve as part of an electrical connection, for example, the flexible circuit boards 170, 230 and their grounding wires 320 may be connected to the support structure 300 to provide a stable electrical ground.

[0110] According to the above-described embodiments disclosed herein, by setting up dual light mixing zones and extending the light guide plate, and placing the extended portion in the light mixing zone, it can be ensured that reducing the thickness of the light guide plate to accommodate the thinner design of the touch display device will not affect the overall optical performance of the touch display device.

[0111] Although the present disclosure has been described above with reference to embodiments, it is not intended to limit the present disclosure. Any person skilled in the art may make various modifications and alterations 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 appended claims.

Claims

1. A touch display device, characterized in that, Include: A cover plate having a visible area and a peripheral area, wherein the peripheral area is provided with an ink layer; A housing, together with the cover plate, forms an accommodating space; A front optical module, comprising: A light guide plate having a light incident surface on one side; and A light source module, comprising: A plurality of light-emitting diodes, wherein each of the plurality of light-emitting diodes has a light-emitting surface facing the side light-incident surface, a reflective surface opposite to the light-emitting surface, and a continuous uniform light-emitting 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, which supports the light guide plate; A touch module is located between the cover plate and the front light module, and has a side of the touch module facing the light source module. The light guide plate has an extension beyond the vertical projection range of the touch module on the light guide plate. The extension has an exposed portion that is not covered by the first reflective layer and not covered by the second reflective layer, and the exposed portion is exposed to the air. A reflective display module, comprising: A reflective display, wherein the vertical projection of the reflective display onto the cover plate does not overlap with the vertical projection of the plurality of light-emitting diodes onto the cover plate; and A light-shielding element is connected to the reflective display. in: The plurality of 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 region; and The side of the touch module, the ink layer, the housing, and the light-shielding element form a second light mixing area, and the extension of the light guide plate is located in the second light mixing area.

2. The touch display device as described in claim 1, characterized in that, The light guide plate has an upper surface and a lower surface relative to the upper surface, and the exposed portion is substantially flat on the upper surface and the lower surface and is in direct contact with the air.

3. The touch display device as described in claim 1, characterized in that, The light guide plate has an upper surface and a lower surface relative to the upper surface, and the length of the exposed portion on the upper surface is less than the length of the exposed portion on the lower surface.

4. The touch display device as described in claim 1, characterized in that, The continuous uniform light surface is a translucent frosted surface.

5. The touch display device as claimed in claim 1, characterized in that, The front light module further includes a first optical adhesive layer and a second optical adhesive layer. 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. 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 of the plurality of light-emitting diodes.

6. The touch display device as described in claim 5, characterized in that, The lower surface of the second optical adhesive layer is flush with the lower surface of each of the plurality of light-emitting diodes.

7. The touch display device as described in claim 5, characterized in that, The light transmittance of the first optical adhesive layer and the second optical adhesive layer is 91% to 99.9% respectively.

8. The touch display device as claimed in claim 1, characterized in that, The vertical projection of the light-incident surface of the light guide plate onto the cover plate does not overlap with the vertical projection of the reflective display onto the cover plate.

9. The touch display device as claimed in claim 1, characterized in that, The reflective display has a display side facing the light-emitting surface of each of the plurality of light-emitting diodes, and the vertical projection of the display side onto the light guide plate falls in the exposed portion.

10. The touch display device as claimed in claim 1, characterized in that, 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 plurality of light-emitting diodes form an air cavity, and the first reflective layer has an inclined surface at the position corresponding to the air cavity.

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