Front light guide module, touch display device and manufacturing method of touch display device

Abstract

The invention discloses a front light guide module, a touch display device and a manufacturing method of the touch display device. The front light guide module comprises a light guide plate, a light source module and a composite light path adjusting layer. The light guide plate has a thickness of 0.1 to 0.3 mm and is provided with an optical microstructure. The light source module comprises a flexible circuit board and a light emitting diode. The flexible circuit board has a non-transparent reflective surface and bears a part of the light guide plate. The light-emitting diode is arranged on the opaque reflective surface and is aligned with the side light incident surface of the light guide plate, and the vertical distance between the upper surface of the light-emitting diode and the flexible circuit board is smaller than or equal to the vertical distance between the upper surface of the light guide plate and the flexible circuit board. The composite light path adjusting layer comprises a reflecting layer and a shading layer. The reflecting layer covers the light-emitting diode and the upper surface of the light guide plate part. The shading layer is stacked on the reflecting layer. A brightness average value gt of the front light guide module; 120 cd / m < 2 >, and the brightness uniformity is gt; 80%. The design can ensure that the optical performance and the structural stability of the front light guide module are not influenced by thinning the light guide plate in response to the thin design.

Description

Technical Field

[0001] The present disclosure relates to a front light guide module, a touch display device including the front light guide module, and a manufacturing method of the touch display device. Background Art

[0002] In this era of information explosion, people need to read books, documents, instant messages, etc. extensively every day, but traditional liquid crystal displays (LCD) and organic light emitting diode displays (OLED) are not suitable for long-term reading. Therefore, reflective display devices such as electrophoretic displays (EPD) and cholesteric liquid crystal displays (CLCD) have gradually received attention.

[0003] Generally speaking, in order to provide display functions in dark or dimly lit places, reflective display devices are often equipped with a front light guide plate, but this is not conducive to meeting the design requirements of thinness when further integrating the touch panel to form a touch display device. The prior art uses thinning the thickness of the light guide plate as one of the solutions. However, the thinned light guide plate is prone to other problems and causes structural or optical defects in the touch display device, such as insufficient structural stability, insufficient brightness, hot spot problems, etc. Therefore, how to balance the thin design, structural stability and optical performance of the touch display device is a direction worth studying at present. Summary of the invention

[0004] According to some embodiments of the present disclosure, a front light guide module is arranged on a reflective display and includes a light guide plate, a light source module and a composite light path adjustment layer. The light guide plate has a thickness of 0.1 mm to 0.3 mm and includes an upper surface, a lower surface relative to the upper surface and a side light incident surface connecting the upper surface and the lower surface, wherein at least one of the upper surface and the lower surface is provided with a plurality of optical microstructures. The light source module includes a flexible circuit board and a plurality of light emitting diodes. The flexible circuit board has an opaque reflective surface and carries a portion of the light guide plate. The light emitting diode and the light guide plate are arranged coplanarly on the opaque reflective surface of the flexible circuit board, and the light emitting diode is aligned with the side light incident surface, and the vertical distance from the upper surface of any one of the light emitting diodes to the flexible circuit board is less than or equal to the vertical distance from the upper surface of the light guide plate to the flexible circuit board. The composite light path adjustment layer includes a reflective layer and a light shielding layer. The reflective layer covers the upper surface of the light emitting diode and part of the light guide plate. The light shielding layer is stacked on the reflective layer and is relatively far away from the light emitting diode and the light guide plate. The average brightness of the front light module on the reflective display is greater than 120cd / m2 , and the brightness uniformity is greater than 80%.

[0005] In some embodiments of the present disclosure, a plurality of light emitting diodes are arranged at intervals, and a distance between two adjacent light emitting diodes is 1.5 mm to 20 mm.

[0006] In some embodiments of the present disclosure, a vertical distance between a light emitting surface of any light emitting diode and a side light incident surface of the light guide plate is 0.01 mm to 0.6 mm.

[0007] In some embodiments of the present disclosure, the light source module is a coverless light source.

[0008] In some embodiments of the present disclosure, the side light incident surface of the light guide plate is a substantially flat surface.

[0009] According to other embodiments of the present disclosure, a touch display device includes a reflective display, a front light guide module, a touch sensor, and a cover plate. The touch sensor is disposed on the reflective display. The front light guide module is disposed between the reflective display and the touch sensor. The cover plate is disposed on the touch sensor and relatively away from the front light guide module.

[0010] In some embodiments of the present disclosure, the touch display device further includes a first adhesive layer, a second adhesive layer, and a third adhesive layer. The first adhesive layer is disposed between the touch sensor and the front light guide module. The second adhesive layer is disposed between the front light guide module and the reflective display. The third adhesive layer is disposed between the cover plate and the touch sensor. The thickness of the third adhesive layer is greater than the thickness of the first adhesive layer and greater than the thickness of the second adhesive layer.

[0011] According to some other embodiments of the present disclosure, a method for manufacturing a touch display device includes: laminating a touch sensor to a first side of a front light guide module through a first adhesive layer; laminating a reflective display to a second side of the front light guide module through a second adhesive layer, wherein the first side of the front light guide module faces away from the second side; and laminating a cover plate having a shielding layer to the touch sensor through a third adhesive layer, such that the cover plate and the front light guide module are located on opposite sides of the touch sensor, wherein the shielding layer faces the touch sensor and contacts the third adhesive layer, and the thickness of the third adhesive layer is greater than the thickness of the first adhesive layer and greater than the thickness of the second adhesive layer.

[0012] In some embodiments of the present disclosure, the step of laminating the cover plate to the touch sensor is performed after the step of laminating the touch sensor and the reflective display to the front light guide module.

[0013] In some embodiments of the present disclosure, the thickness of the first adhesive layer and the thickness of the second adhesive layer are each 50 micrometers to 75 micrometers, and the thickness of the third adhesive layer is 100 micrometers to 125 micrometers.

[0014] According to the above-mentioned embodiments of the present disclosure, based on the collocation of the light guide plate, the light source module and the composite optical path adjustment layer in the front light guide module, it can be ensured that the thinning of the light guide plate in response to the thin design of the front light guide module will not affect the overall optical performance and structural stability of the front light guide module. In addition, when the thin front light guide module is set in the touch display device, the collocation design of the multi-layer adhesive layer will not only not increase the overall thickness of the touch display device, but also effectively avoid the problem of decreased bonding yield caused by the gap of the shielding layer of the cover plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order 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:

[0016] Figure 1A is a top view schematic diagram of a front light guide module according to some embodiments of the present disclosure;

[0017] Figure 1B for Figure 1A A schematic cross-sectional view of the front light guide module taken along line segment AA';

[0018] Figure 2 is a schematic cross-sectional view of a touch display device according to some embodiments of the present disclosure, wherein the cross-sectional position is the same as Figure 1A The line segment A-A';

[0019] FIG. 3A to FIG. 3C 1 is a schematic cross-sectional view of a method for manufacturing a touch display device 1 according to some embodiments of the present disclosure in different steps. Figure 1A The line segment A-A'; and

[0020] Figure 4 FIG. 1 is a schematic diagram of the locations of points for measuring brightness of a front light guide module according to some embodiments of the present disclosure.

[0021]

Explanation of symbols

[0022] 1: Touch display device

[0023] 10: Front light module

[0024] 20: Reflective Display

[0025] 30: Touch sensor

[0026] 35: Flexible circuit board

[0027] 40: Cover

[0028] 42: Shielding layer

[0029] 50: first adhesive layer

[0030] 60: Second adhesive layer

[0031] 70: The third adhesive layer

[0032] 100: Light guide plate

[0033] 100a: Part 1

[0034] 100b: Part 2

[0035] 101: Upper surface

[0036] 103: Lower surface

[0037] 105: Side light input surface

[0038] 110:Optical microstructure

[0039] 200: Light source module

[0040] 210: Flexible printed circuit board

[0041] 210a: base

[0042] 210b: Extension

[0043] 211: Opaque reflective surface

[0044] 213: Inner wall

[0045] 220: Light Emitting Diode

[0046] 221: Upper surface

[0047] 225: Luminous surface

[0048] 300: Composite light path adjustment layer

[0049] 303: Inner wall

[0050] 310: Reflective layer

[0051] 311: Surface

[0052] 320: Light shielding layer

[0053] 400: Adhesive layer

[0054] H1,H2:Thickness

[0055] D1, D2, D3: vertical distance

[0056] T1, T2, T3: thickness

[0057] PA: Peripheral area

[0058] VA: Visual Area

[0059] P: Spacing

[0060] S: Space

[0061] A: Distance

[0062] A-A': Line segment

[0063] S10~S30: Steps DETAILED DESCRIPTION

[0064] The following will disclose multiple embodiments of the present disclosure with the accompanying drawings. For the sake of clarity, many practical details will be described together in the following description. However, these practical details should not be used to limit the present disclosure. In addition, for the convenience of the reader, the size of each element in the accompanying drawings is not drawn according to the actual scale. In addition, relative terms such as "lower" and "upper" can be used in this article to describe the relationship between one element and another element, as shown in the accompanying drawings. It should be understood that relative terms are intended to include different orientations of the device other than the orientation shown in the figure. In addition, the terms "first", "second", etc. mentioned in the specification or the scope of the patent application are only used to name different elements, or to distinguish different embodiments or scopes, and are not used to limit the upper or lower limit on the number of elements, nor to limit the manufacturing order or setting order of the elements.

[0065] See also Figure 1A and Figure 1B ,in Figure 1A is a top view of a front light guide module 10 according to some embodiments of the present disclosure, and Figure 1B for Figure 1A A schematic cross-sectional view of the front light guide module 10 taken along line segment AA'. For clear presentation, Figure 1A Only draw Figure 1B The front light guide module 10 includes the light guide plate 100, the light source module 200 and the composite light path adjustment layer 300. The front light guide module 10 disclosed herein can be applied to a reflective display device or a reflective touch display device. The light guide plate 100 is used to guide the transmission of light (light beam), and the light source module 200 is used to provide light to the light guide plate 100 and cooperate with the composite light path adjustment layer 300 to improve the light utilization rate and contribute to the thinning of the front light guide module 10. In the following description, each of the above components will be described in detail.

[0066] The light guide plate 100 has an upper surface 101, a lower surface 103 and a side light incident surface 105, wherein the upper surface 101 is opposite to the lower surface 103, and the side light incident surface 105 connects the upper surface 101 and the lower surface 103 and faces the light emitting diode 220 in the light source module 200. A plurality of optical microstructures 110 are arranged on the upper surface 101 or the lower surface 103 of the light guide plate 100, and the optical microstructures 110 are used to destroy the total reflection phenomenon of light in the light guide plate 100, so that the light guide plate 100 can adjust to refract (guide) part of the light to the reflective display device (not shown) located below the front light guide module 10, and then evenly refract the light reflected by the reflective display device so that the user can watch the image screen. In this regard, the design requirements of the light guide plate 100 in the front light guide module 10 of this embodiment are completely different from the design requirements of the light guide plate of the backlight module in the traditional liquid crystal display (providing sufficient backlight to pass through the liquid crystal display screen). The light guide plate 100 may have a first portion 100a and a second portion 100b. When the light guide module 10 is applied to a reflective display device, the first portion 100a of the light guide plate 100 may correspond to the visible area VA of the device, and the second portion 100b of the light guide plate 100 may correspond to the peripheral area PA of the device. In some embodiments, the optical microstructure 110 may be disposed on the upper surface 101 and / or the lower surface 103 of the first portion 100a and the second portion 100b. To improve the uniformity of light, the optical microstructure 110 may have a denser distribution pattern at a position relatively close to the light source module 200, and may have a sparser distribution pattern at a position relatively far from the light source module 200. It should be understood that the layout position and pattern of the optical microstructure 110 are not limited by the present disclosure and may be adjusted according to actual needs. In some embodiments, the light guide plate 100 may include polycarbonate (PC), polymethyl methacrylate (PMMA), polyolefin or a combination thereof, and is preferably designed to be flexible.

[0067] In order to cope with the thin design of the front light guide module 10, the thickness H1 of the light guide plate 100 disclosed in the present invention is designed to be 0.1 mm to 0.3 mm. For example, the thickness H1 of the light guide plate 100 may be 0.15 mm, 0.2 mm or 0.25 mm. However, it is worth noting that although simply thinning the light guide plate 100 intuitively helps the thin design of the front light guide module 10, it will lead to other problems and cause the front light guide module 10 to have structural or optical defects. For example, in terms of structure, the thinned light guide plate 100 has a lowered upper surface 101, which may produce a height difference with other elements located on the same plane, resulting in the need to set up an additional flat layer or a thicker adhesive layer to overcome the height difference, or even require other laminated layers to make way for each other in space; in terms of optics, the thinned light guide plate 100 may cause a decrease in the amount of light entering the side light incident surface 105, resulting in insufficient brightness, and may also result in a reduction in the light mixing space, resulting in uneven light near the light incident side of the light guide plate 100 (i.e., a hot spot problem). Based on the above, the present disclosure not only thins the light guide plate 100 in response to the thin design of the front light guide module 10, but also improves and solves many problems derived from the thinning of the light guide plate 100, thereby taking into account the overall applicability of the front light guide module 10. The detailed implementation method will be described later.

[0068] The light source module 200 includes a flexible circuit board 210 and a plurality of light emitting diodes 220, wherein the flexible circuit board 210 has an opaque reflective surface 211 and carries a portion of the light guide plate 100, and the light emitting diodes 220 and the light guide plate 100 are coplanarly arranged on the opaque reflective surface 211 of the flexible circuit board 210, so that the front light guide module 10 as a whole belongs to the design of a side-emitting light source. It should be understood that in this article, when describing that two elements are coplanarly arranged on a surface, it means that the two elements are generally directly or indirectly arranged with the surface as a planar substrate. The indirect arrangement mentioned here means that when the elements are arranged on the surface, they are arranged by a necessary means (necessary spacers), such as Figure 1B As shown in the adhesive layer 400, the light guide plate 100 is indirectly disposed on the opaque reflective surface 211 of the flexible circuit board 210 through the adhesive layer 400, and the adhesive layer 400 is a necessary means for the light guide plate 100 to be attached to the opaque reflective surface 211; other components such as the light emitting diode 220 are actually disposed on the opaque reflective surface 211 through a solder layer (not shown). In addition, the light guide plate 100 and the light emitting diode 220 disposed on the flexible circuit board 210 in the same plane are adjacent to each other and are disposed with a gap, and are not in direct contact with each other (the adjacent light guide plates 100 and light emitting diodes 220 are disposed with a gap), and thus in the overall structure, a space S is enclosed between the light guide plate 100, the light source module 200, the composite optical path adjustment layer 300 and the adhesive layer 400.

[0069] The flexible printed circuit board 210 has a base portion 210a and an extension portion 210b connected to each other, wherein the base portion 210a carries the light emitting diode 220, and the extension portion 210b carries part of the light guide plate 100. The flexible printed circuit board 210 may be, for example, a multi-layer structure, wherein the outermost layer is designed as an opaque reflective surface 211. Specifically, when the light emitting diode 220 emits light (light beam), the light will have a scattering problem. In this embodiment, the design of the opaque reflective surface 211 controls the reflection of the scattered light and makes it enter the light guide plate 100 from the side incident surface 105 in a more concentrated manner, thereby improving the problem of a decrease in the amount of light that may occur due to the thinning of the light guide plate 100. In some embodiments, the opaque reflective surface 211 of the flexible printed circuit board 210 is configured on the entire surface, so that it can be ensured that light incident on any position of the opaque reflective surface 211 can be reflected. In some embodiments, the opaque reflective surface 211 may be directly an ink coating layer, a chemical plating layer, an electroplating layer, or the like, or may be formed by attaching a white auxiliary material layer to improve the reflectivity of light.

[0070] It should be supplemented that, since part of the light guide plate 100 is set on the opaque reflective surface 211 through the adhesive layer 400, although the actual thickness of the adhesive layer 400 is relatively thin, the amount of light entering the adhesive layer 400 and the impact received in the adhesive layer 400 can be ignored, but in some embodiments, the adhesive layer 400 can use an optically clear adhesive (OCA) with high light transmittance, so that a small amount of light that does not enter the light guide plate 100 from the side light incident surface 105 can be reflected by the opaque reflective surface 211 and penetrate the adhesive layer 400 to be guided back to the light guide plate 100, which helps to improve the utilization rate of light.

[0071] A plurality of light emitting diodes 220 are aligned with the side light incident surface 105 of the light guide plate 100, and the light emitting surface 225 of the light emitting diodes 220 faces the side light incident surface 105 of the light guide plate 100. As mentioned above, the thin design of the light guide plate 100 may affect the structural stability and optical performance of the front light guide module 10. In order to solve the structural and optical problems further derived from the thinning of the light guide plate 100, the present disclosure adjusts the structural design so that the vertical distance from the upper surface 221 of the light emitting diode 220 to the flexible circuit board 210 is less than or equal to the vertical distance from the upper surface 101 of the light guide plate 100 to the flexible circuit board 210. More precisely, the vertical distance D1 from the upper surface 221 of the light emitting diode 220 to the opaque reflective surface 211 of the flexible circuit board 210 is less than or equal to the vertical distance D2 from the upper surface 101 of the light guide plate 100 to the opaque reflective surface 211 of the flexible circuit board 210. It should be understood that, as described above, the light guide plate 100 and the light emitting diode 220 can be respectively disposed on the flexible circuit board 210 by any appropriate necessary means. Therefore, as long as the light guide plate 100 and the light emitting diode 220 are disposed on the flexible circuit board 210, the vertical distance D1 from the upper surface 221 of the light emitting diode 220 to the flexible circuit board 210 is less than or equal to the vertical distance D2 from the upper surface 101 of the light guide plate 100 to the flexible circuit board 210, they all fall within the scope covered by the present disclosure.

[0072] As mentioned above, since the upper surface 221 of the light-emitting diode 220 will not be higher than the upper surface 101 of the light guide plate 100 in relative position, it can be ensured that the light emitted by the light-emitting diode 220 can be aligned with the side light incident surface 105 (the light can be located within the vertical projection range of the side light incident surface 105 toward the light-emitting diode 220), thereby avoiding the situation where the light cannot enter the light guide plate 100 from the side light incident surface 105 because the light path is located outside the vertical projection range of the side light incident surface 105 of the light guide plate 100, and it can be completely avoided that these light rays located outside the vertical projection range of the side light incident surface 105 become noise light and interfere with the light guiding effect of the light guide plate 100.

[0073] On the other hand, the composite optical path adjustment layer 300 includes a reflective layer 310 and a light shielding layer 320. The reflective layer 310 covers the upper surface 101 of the LED 220 and the light guide plate 100, and the light shielding layer 320 is stacked on the reflective layer 310 and relatively away from the LED 220 and the light guide plate 100, that is, the light shielding layer 320 is stacked on the surface 311 of the reflective layer 310 that is opposite to the LED 220 and the light guide plate 100. More specifically, the reflective layer 310 and the shading layer 320 both extend from the upper surface 221 of the light-emitting diode 220 to the upper surface 101 of the light guide plate 100 and completely cover the space S between the light-emitting diode 220 and the light guide plate 100, and the space S is located between the reflective layer 310 and the opaque reflective surface 211 of the aforementioned flexible circuit board 210 in the vertical direction of the upper surface 101 of the light guide plate 100. Therefore, it can be ensured that light of any path traveling in the space S can be reflected by the reflective layer 310 and the opaque reflective surface 211 of the aforementioned flexible circuit board 210 and enter the light guide plate 100 from the side light incident surface 105 in a more concentrated manner, thereby improving the problem of decreased light input that may occur due to thinning of the light guide plate 100.

[0074] Furthermore, the light shielding layer 320 is closer to the user than the reflective layer 310, and is used to absorb or shield various outgoing light rays existing in the peripheral area PA to avoid affecting the user's visual effect. For example, the light shielding layer 320 can absorb or shield light rays that directly penetrate the reflective layer 310.

[0075] In some embodiments, when viewed from a top-down angle ( Figure 1A When viewed from a viewing angle (of a certain angle), the reflective layer 310 and the light shielding layer 320 can completely overlap, that is, the vertical projections of the reflective layer 310 and the light shielding layer 320 toward the flexible printed circuit board 210 completely overlap, thereby achieving a better light shielding effect. In some embodiments, the inner side wall 303 of the composite optical path adjustment layer 300 is closer to the visual area VA than the inner side wall 213 of the flexible printed circuit board 210, that is, the inner side wall 303 of the composite optical path adjustment layer 300 is farther away from the light emitting diode 220 than the inner side wall 213 of the flexible printed circuit board 210. In this way, it can be ensured that after the light is reflected by the opaque reflective surface 211 of the flexible printed circuit board 210, it can still be reflected and shielded by the composite optical path adjustment layer 300, thereby achieving the effect of stabilizing the light.

[0076] In some embodiments, the light shielding layer 320 can be formed on the reflective layer 310 by any suitable method, wherein the reflective layer 310 can be an ink coating film layer, a chemical plating film layer or an electroplating film layer, and is preferably white to improve the reflectivity of light, and the material of the light shielding layer 320 can be polyimide, tape, etc., and is preferably dark (such as black) to achieve a good light absorption or light shielding effect. More specifically, the composite optical path adjustment layer 300 can use the light shielding layer 320 as a substrate, and white ink is coated on one surface of the substrate as the reflective layer 310. In other embodiments, the composite optical path adjustment layer 300 can be a substrate, and white ink is coated on two opposite surfaces of the substrate as the reflective layer 310 and black ink is coated as the light shielding layer 320. In some embodiments, the reflective layer 310 can be attached to the light guide plate 100 and the light emitting diode 220 by optical adhesive. In other embodiments, the reflective layer 310 itself may be adhesive to directly adhere to the light guide plate 100 and the light emitting diode 220. In general, the thickness H2 of the composite optical path adjustment layer 300 may be 28 micrometers to 32 micrometers to achieve a thin design while stabilizing the light.

[0077] In some embodiments, Figure 1AAs shown, a plurality of LEDs 220 are arranged at intervals along the side light incident surface 105 of the light guide plate 100 on the opaque reflective surface 211 of the flexible printed circuit board 210, and the pitch P between two adjacent LEDs 220 can be 1.5 mm to 20 mm (e.g., 1.8 mm). The pitch P in this embodiment refers to the distance between the center points of two adjacent LEDs 220. In addition, the distance A from the light emitted by each LED 220 in the front light guide module 10 to the uniform mixing of the light of the overall light source (actually, for example, the distance from the light emitting surface 225 of the LED 220 to the boundary between the visible area VA and the peripheral area PA) can be regarded as a light mixing area of ​​the front light guide module 10. In order to enable the front light guide module 10 to have a better light mixing effect while meeting the requirements of the narrow frame of the product, the design can meet the relationship of "the value of A / P is greater than 0.8". In other words, this embodiment can not only reduce the difference in the range of the bright and dark areas formed between the light-emitting diodes 220, but also reduce the width of the peripheral area PA and increase the area of ​​the visible area VA by reducing the spacing P between two adjacent light-emitting diodes 220. In a preferred embodiment, a plurality of light-emitting diodes 220 are arranged equidistantly on the opaque reflective surface 211 of the flexible circuit board 210 to improve the uniformity of the light. In some embodiments, the light-emitting diodes 220 may be, for example, sub-millimeter light-emitting diodes (Mini Light-Emitting Diode, Mini LED). Due to the small size of sub-millimeter light-emitting diodes, more light-emitting diodes 220 can be arranged in a unit volume of space, so that more light can enter the light guide plate 100, thereby improving the overall brightness, and the small size of the light-emitting diodes 220 also helps to reduce the spacing P of the light-emitting diodes 220 in arrangement.

[0078] In some embodiments, the vertical distance D3 between the light emitting surface 225 of the LED 220 and the side light incident surface 105 of the light guide plate 100 may be 0.01 mm to 0.6 mm (e.g., 0.5 mm). Thus, under the condition that the LED 220 is not too far away from the light guide plate 100, the light transmission efficiency from the light emitting surface 225 of the LED 220 to the side light incident surface 105 of the light guide plate 100 can be ensured by the gap formed by the vertical distance D3, so as to increase the amount of light entering the light guide plate 100.

[0079] In some embodiments, the light source module 200 may be a coverless light source. In detail, the light emitting diode 220 in the light source module 200 is not covered by a focusing element in the form of a housing or a housing, that is, the light emitted by the light emitting diode 220 will not be reflected and gathered by a focusing element in the form of a housing or a housing. In general, based on the configuration of the opaque reflective surface 211 of the flexible circuit board 210, the design of the vertical distance D1 from the light emitting diode 220 to the flexible circuit board 210 and the vertical distance D2 from the light guide plate 100 to the flexible circuit board 210, and the configuration of the composite optical path adjustment layer 300, most of the light emitted by the light emitting diode 220 can enter the light guide plate 100, so there is no need to set up an additional focusing element to improve the utilization rate of the light. In this way, the structural discontinuity between the light source module 200 and the light guide plate 100 due to its large volume can be avoided, which helps to improve the stability of the overall structure and contributes to the thinning of the overall device.

[0080] It is worth noting that in the conventional technology in this field, the use of a thicker light guide plate and a light source with a larger size of LEDs can usually meet the required amount of light input. However, the distance between the large-sized LEDs will also be relatively large. Therefore, the light emitted by the light source is prone to produce obvious bright and dark bands due to uneven light mixing when mixing, thereby forming hot spots. In order to solve this problem, a light absorption layer is usually set near the light input area to absorb the chaotic light before the light enters the light mixing area, thereby stabilizing the light to improve the hot spot problem. However, since the light emitting diodes 220 disclosed in the present invention can be smaller sub-millimeter light emitting diodes, it is easier to shorten the distance between adjacent light emitting diodes 220 when arranging the light emitting diodes 220, so that the light emitted by the light emitting diodes 220 can be prevented from producing obvious bright and dark bands in the light mixing area (i.e., the area of ​​the light guide plate 100 relatively close to the side light input surface 105). In addition, since the present disclosure adopts a thin light guide plate 100, the light input amount is the priority factor. Therefore, the present disclosure does not need and cannot set an additional light absorption layer at the relative position of the vertical projection of the light mixing area, otherwise it will affect the light input amount.

[0081] On the other hand, in the conventional technology in this field, in order to stabilize the light before it enters the mixed light area, it is avoided to set a reflective layer (reflective layer) near the light-entering area to prevent the light from being constantly reflected and unable to be stabilized. However, the present disclosure is based on the size design of the light-emitting diode 220 and does not face the hot spot problem. Therefore, a reflective layer (i.e., the reflective layer 310 of the present disclosure and the opaque reflective surface 211 of the flexible circuit board 210) can be set near the light-entering area. In this way, the light can be reflected by the functional layer with reflective properties to increase the amount of light entering, so as to ensure that the overall brightness can be maintained or even improved under the thin design of the light guide plate 100. Furthermore, since in the present disclosure, the amount of light entering is increased by setting a functional layer with reflective properties near the light-entering area located in the peripheral area PA, there is no need to set other reflective layers in the visible area VA to increase the brightness of the visible area VA. It is additionally noted that when a reflective layer is provided in the visible area VA, the visibility requirement of the visible area VA must be considered, so a transparent material is often used to form the reflective layer, and the configuration of the reflective layer will affect the visibility of the visible area VA to some extent. In this regard, since the present disclosure does not require an additional reflective layer to be provided in the visible area VA, the difficulty in material matching can be eliminated, and the visibility of the visible area VA can be avoided from being affected by the provision of the reflective layer.

[0082] In addition, in the conventional technology in this field, based on the hot spot problem caused by the large-sized light source, the side light incident surface of the light guide plate is usually designed to be a rough surface, so that the light incident surface of the light guide plate is uneven and undulating, which increases the probability of light being reflected multiple times at the light incident surface and entering the light guide plate, thereby increasing the amount of light entering. However, the present disclosure can improve the hot spot problem and increase the brightness based on the size design of the light-emitting diode 220 and the configuration of the light-emitting diode 220 sandwiched between the upper and lower reflective layers (the reflective layer 310 in the composite optical path adjustment layer 300 and the opaque reflective surface 211 of the flexible circuit board 210). Therefore, the side light incident surface 105 of the light guide plate 100 of the present disclosure can be a substantially flat surface. In other words, there is no need to use other processes to damage the side light incident surface 105 of the light guide plate 100 to make it have an uneven surface, thereby simplifying the process. Overall, the present disclosure can simultaneously achieve the effects of improving brightness, improving light mixing effect, stabilizing light and simplifying the process.

[0083] In terms of improving brightness, improving light mixing effect and stabilizing light optical effects, more specifically, when the front light guide module 10 of the present disclosure is set on a reflective display, the average brightness measured is greater than 120 cd / m 2, and the brightness uniformity is greater than 80%. This optical feature is specifically verified with reference to each embodiment and each comparative example below. Among them, the stacking structure of comparative examples 1 to 4 and embodiment 1 is to set a front light guide module on the reflective display, while the stacking structure of comparative examples 5 to 8 and embodiment 2 is to sequentially set a front light guide module and a touch sensor on the reflective display, wherein an adhesive layer (the material is acrylic resin (Acrylic) or silicone resin (silicone), with a thickness of about 50 microns to 75 microns) is used to adhere the front light guide module, the reflective display (and the touch sensor) to each other. In terms of the measurement technique, 9 test points (numbered #1 to #9) are selected on the light-emitting surface of the top layer of each stacking structure (the front light guide module in comparative examples 1 to 4 and embodiment 1, and the touch sensor in comparative examples 5 to 8 and embodiment 2), and a brightness meter is used to measure the brightness of the 9 test points. Please refer to the method of selecting points. Figure 4 The actual size of the light guide plate (including the length L and the width W) is used to mark the test points, and the light emitting diode is located on the left side of the light guide plate (near the side of the #7 to #9 test points). The brightness measurement results of each embodiment and each comparative example are shown in Table 1. It should be understood that the embodiments in Table 1 should not be interpreted restrictively on the present disclosure without exceeding the scope of the present disclosure.

[0084] Table 1

[0085]

[0086]

[0087] [Note 1]

[0088] Unless otherwise specified, the stacking structure of the front light guide modules in each comparative example and each embodiment is as follows: Figure 1B The remaining details are as follows:

[0089] Comparative Examples 1 and 5: LEDs of conventional size, light guide plates with a thickness H1 of 0.4 mm, and no reflective layer;

[0090] Comparative Examples 2 and 6: LEDs of conventional size, light guide plates with a thickness H1 of 0.15 mm, and no reflective layer;

[0091] Comparative Examples 3 and 7: LEDs of conventional size, light guide plates with a thickness H1 of 0.15 mm;

[0092] Comparative Examples 4 and 8: mini LED, light guide plate with a thickness H1 of 0.15 mm, and no reflective layer;

[0093] Embodiments 1 and 2: mini LED, light guide plate with a thickness H1 of 0.15 mm.

[0094] [Note 2]

[0095] The brightness uniformity is calculated as: (minimum brightness / maximum brightness)×100%.

[0096] [Note 3]

[0097] The dimensions of the conventional size LED used in the comparative example are: 3 mm (length)×0.85 mm (width)×0.4 mm (height).

[0098] Please refer to Comparative Examples 1 and 5. Comparative Examples 1 and 5 use the design of the traditional non-thin front light guide plate as a reference, that is, a thicker light guide plate and conventional-sized LEDs are used, so the brightness and uniformity are compliant. Please refer to Comparative Examples 2-3 and 5-6. When only the light guide plate is thinned without correspondingly reducing the size of the LED, the brightness and uniformity cannot be improved regardless of whether a reflective layer is set or not. It can be seen that simply thinning the light guide plate will lead to a decrease in the amount of light entering, resulting in insufficient brightness, and will also cause poor light guiding effects and poor uniformity. Please refer to Comparative Examples 4, 8 and Examples 1 and 2. When a thinned light guide plate and a small-sized LED are used, the brightness and uniformity can be greatly improved. When a reflective layer is set, the brightness and uniformity can be further improved. It can be seen that the overall stacking structure of the front light guide module disclosed in the present invention ( Figure 1B The stacked structure design has a significant effect on improving the optical performance. On the other hand, judging from the results of the first group of experiments (Comparative Examples 1-4 and Example 1) and the second group of experiments (Comparative Examples 5-8 and Example 2), whether or not to set a touch sensor on the front light guide module does not have much impact on the optical performance. In addition, since a highly transparent adhesive layer is used, the setting of the adhesive layer has a negligible effect on the optical performance of each comparative example and each example.

[0099] See also Figure 2 , which is a cross-sectional schematic diagram of a touch display device 1 according to some embodiments of the present disclosure, and its cross-sectional position is the same as Figure 1A The touch display device 1 has a visible area VA and a peripheral area PA located on at least one side of the visible area VA. The front light guide module 10 disclosed in the present invention can be integrated into the reflective touch display device 1. In detail, the touch display device 1 includes a front light guide module 10, a reflective display 20 and a touch sensor 30. The front light guide module 10 is disposed on the reflective display 20, and the touch sensor 30 is disposed on the front light guide module 10. In other words, the front light guide module 10 is disposed between the reflective display 20 and the touch sensor 30.

[0100] The touch display device 1 further includes a cover plate 40. The cover plate 40 is disposed on the touch sensor 30 and is relatively far away from (facing away from) the front light guide module 10. In more detail, the cover plate 40 is disposed on the side of the light emitting surface of the front light guide module 10, that is, on the side of the upper surface 101 of the light guide plate 100. Since the material of the cover plate 40 has a certain stiffness, for example, it can be glass, quartz or a suitable polymer (for example, polycarbonate (PC), polymethyl methacrylate (PMMA)), it can provide a protective effect for the touch display device 1. In addition, a shielding layer 42 is also disposed on the side of the cover plate 40 facing the front light guide module 10, which is used to define the peripheral area PA and enhance the concealment of the components (for example, the flexible circuit board 35 connected to the touch sensor 30) on the back side of the cover plate 40 located in the peripheral area PA. The shielding layer 42 can extend from the edge of the cover plate 40 to the visible area VA, so that the defined peripheral area PA and the visible area VA have a boundary.

[0101] From the perspective of the overall stacked structure of the touch display device 1, compared to the visible area VA, the number of components located in the peripheral area PA is larger, the stacking relationship is more complicated, and the heights of the components are inconsistent, which can easily lead to component damage during the subsequent lamination. Therefore, in order to avoid mechanical interference, the design often requires layout concessions or openings, etc., which reduces the stability of the structure. However, in the present disclosure, the light-emitting diode 220 has a reduced thickness in response to the thinned light guide plate 100 design, so the height difference between the peripheral area PA and the visible area VA can be reduced, which helps to improve the problem of mechanical interference in the peripheral area PA, improve the stability of the overall structure, and there is no need to set a thicker adhesive layer to overcome the severe difference, thereby achieving the thinning of the overall device. In addition, the thickness H2 of the composite optical path adjustment layer 300 (see Figure 1A ) can be 28 microns to 32 microns. This design not only can stabilize the light while taking into account the thin design as mentioned above, but also can reduce the height difference between the visible area VA and the peripheral area PA, thereby improving the stability of the overall structure.

[0102] In some embodiments, the touch display device 1 may further include an adhesive layer for bonding the layers. In detail, the first adhesive layer 50 is disposed between the touch sensor 30 and the front light guide module 10, and the second adhesive layer 60 is disposed between the front light guide module 10 and the reflective display 20, and the third adhesive layer 70 is disposed between the cover plate 40 and the touch sensor 30. In some embodiments, each adhesive layer may be an optically transparent adhesive with high light transmittance. In addition, in order to cope with the thin design of the touch display device 1, the thickness T1 of the first adhesive layer 50 and the thickness T2 of the second adhesive layer 60 may be thinned, while the thickness T3 of the third adhesive layer 70 is relatively thick to fill the gap caused by the shielding layer 42 of the cover plate 40, so as to avoid the third adhesive layer 70 from generating bonding bubbles due to the excessively thin thickness, thereby affecting the product yield. In other words, the thickness T3 of the third adhesive layer 70 is greater than the thickness T1 of the first adhesive layer 50, and the thickness T3 of the third adhesive layer 70 is greater than the thickness T2 of the second adhesive layer 60. In more detail, the thickness T3 of the third adhesive layer 70 may be 100 micrometers to 125 micrometers, and the thickness T1 of the first adhesive layer 50 and the thickness T2 of the second adhesive layer 60 may each be 50 micrometers to 75 micrometers.

[0103] On the other hand, it should be understood that in the bonding process, when two relatively stiff material layers are bonded to each other, it is relatively easy to generate bonding bubbles. In addition, in actual operation, after the stiff material layer and the soft material layer are bonded to each other, the formed structure is stiff as a whole. On this basis, in the manufacturing process of the touch display device 1 disclosed in the present invention, the bonding sequence is designed in response to the hard and soft characteristics of each component and the thickness requirements of the aforementioned adhesive layers. The bonding of the stiff material layer is achieved through a relatively thick adhesive layer; and the bonding involving the soft material layer is achieved by relatively thinner adhesive layers. Specifically, the touch display device 1 disclosed in the present invention can be formed by sequentially performing the following bonding steps S10 to S30, and please also refer to FIG. 3A to FIG. 3C For ease of understanding, it is a cross-sectional schematic diagram of a manufacturing method of a touch display device 1 according to some embodiments of the present disclosure in different steps. For the sake of convenience of explanation, FIG. 3A to FIG. 3C Only schematic blocks are used to represent the front light guide module 10, the reflective display 20, the touch sensor 30 and the cover plate 40. The specific structure of each component can refer to the above description. The reflective display 20 and the cover plate 40 disclosed in the present invention are rigid material layers; while the front light guide module 10 and the touch sensor 30 are soft material layers.

[0104] See also Figure 3A. First, in step S10, the touch sensor 30 is bonded to the first side S1 of the front light guide module 10 through the first adhesive layer 50, wherein the first side S1 is a side of the light emitting surface of the front light guide module 10. In other words, step S10 is a bonding step between two soft material layers, and after the bonding is completed, the formed structure is still a soft material layer as a whole. In addition, since this step belongs to the bonding between soft material layers, the use of the first adhesive layer 50 with a relatively small thickness T1 for bonding will not cause bubbles to be generated, and can contribute to the thin design of the touch display device 1.

[0105] See also Figure 3B Next, in step S20, the reflective display 20 is attached to the second side S2 of the front light guide module 10 through the second adhesive layer 60, wherein the second side S2 is opposite to the first side S1. Figure 3A The structure of the reflective display 20 is a soft material layer, and the reflective display 20 is a stiff material layer. Therefore, step S20 is a step of laminating a soft material layer with a stiff material layer. Therefore, the structure formed after laminating is a stiff material layer. However, since this step also involves laminating with the soft material layer, the use of the second adhesive layer 60 with a relatively small thickness T2 for laminating will not cause bubbles to be generated, and can help to achieve a thinner design of the touch display device 1.

[0106] See also Figure 3C Then, in step S30, the cover plate 40 is attached to the touch sensor 30 through the third adhesive layer 70, wherein the shielding layer 42 on the cover plate 40 faces the touch sensor 30. After the third adhesive layer 70 is attached, the cover plate 40 and the front light guide module 10 are located on opposite sides of the touch sensor 30. Figure 3B The structure of the cover plate 40 is a stiff material layer, and as mentioned above, the cover plate 40 is also a stiff material layer. Therefore, step S30 is a step of laminating two stiff material layers. Therefore, the present disclosure arranges a third adhesive layer 70 with a relatively large thickness T3 for laminating in this step, which can effectively avoid the generation of bubbles. After completing step S30, the corresponding Figure 2 The touch display device 1 is shown.

[0107] In general, by first laminating the touch sensor 30 and the reflective display 20 to the surface of the front light guide module 10 (steps S10-S20), and then laminating the cover plate 40 to the surface of the touch sensor 30 (step S30), it can be ensured that the lamination between the two stiff material layers is performed using a thicker adhesive layer, and the gap caused by the shielding layer 42 of the cover plate 40 can be filled at the same time, so that the product lamination yield can be improved, and it is helpful for the touch display device 1 to pass the product reliability test. After actual measurement, the touch display device 1 has no bubbles after the reliability tests of high temperature and high humidity test, hot and cold shock test and anti-aging test. In other embodiments, the reflective display 20 may be first attached to one surface of the front light guide module 10, and then the touch sensor 30 may be attached to the other surface of the front light guide module 10, that is, step S20 may be performed first and then step S10. Under such a laminating sequence, since steps S10 and S20 are both laminating between a soft material layer and a stiff material layer, bubbles are not easily generated.

[0108] According to the above-mentioned embodiments of the present disclosure, based on the collocation of the light guide plate, the light source module and the composite optical path adjustment layer in the front light guide module, it can be ensured that the thinning of the light guide plate in response to the thin design of the front light guide module will not affect the overall optical performance and structural stability of the front light guide module. In addition, when the thin front light guide module is set in the touch display device, the collocation design of the multi-layer adhesive layer further not only does not increase the overall thickness of the touch display device, but also effectively avoids the problem of decreased bonding yield caused by the gap of the shielding layer of the cover plate, thereby taking into account the thin design and product performance of the touch display device, ensuring that the touch display device can still have a good product bonding yield and pass the reliability test under the thin design.

[0109] Although the present disclosure has been disclosed in the above embodiments, it is not intended to limit the present disclosure. Anyone familiar with this technology can 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 should be determined by the attached claims.

Claims

1. A front light guide module, characterized in that: The device is disposed on a reflective display and comprises: A light guide plate having a thickness of 0.1 mm to 0.3 mm and comprising an upper surface, a lower surface opposite to the upper surface, and a light incident surface connecting the upper surface and the lower surface, wherein at least one of the upper surface and the lower surface is provided with a plurality of optical microstructures; A light source module, comprising: A flexible printed circuit board having an opaque reflective surface and carrying part of the light guide plate; as well as A plurality of light emitting diodes are disposed on the opaque reflective surface of the flexible printed circuit board in a coplanar manner with the light guide plate, and the plurality of light emitting diodes are aligned with the side light incident surface, wherein a vertical distance from an upper surface of any one of the plurality of light emitting diodes to the flexible printed circuit board is less than or equal to a vertical distance from the upper surface of the light guide plate to the flexible printed circuit board; and A composite optical path adjustment layer, comprising: a reflective layer covering the plurality of light emitting diodes and the upper surface of the light guide plate portion; and a light shielding layer, stacked on the reflective layer and relatively far away from the plurality of light emitting diodes and the light guide plate; The average brightness of the front light guide module on the reflective display is greater than 120 cd / m 2 , and the brightness uniformity is greater than 80%.

2. The front light guide module according to claim 1, characterized in that: The plurality of light emitting diodes are arranged at intervals, and the interval between adjacent light emitting diodes is 1.5 mm to 20 mm.

3. The front light guide module according to claim 1, characterized in that: The vertical distance between a light emitting surface of any one of the plurality of light emitting diodes and the side light incident surface of the light guide plate is 0.01 mm to 0.6 mm.

4. The front light guide module according to claim 1, characterized in that: The light source module is a coverless light source.

5. The front light guide module according to claim 1, characterized in that: The light incident side surface of the light guide plate is a flat surface.

6. A touch display device, characterized in that: Include: a reflective display; a touch sensor disposed on the reflective display; The front light guide module as claimed in claim 1, disposed between the reflective display and the touch sensor; and A cover plate is disposed on the touch sensor and relatively far away from the front light guide module.

7. The touch display device according to claim 6, wherein: Also includes: a first adhesive layer, disposed between the touch sensor and the front light guide module; a second adhesive layer disposed between the front light guide module and the reflective display; and A third adhesive layer is disposed between the cover plate and the touch sensor, wherein the thickness of the third adhesive layer is greater than the thickness of the first adhesive layer and greater than the thickness of the second adhesive layer.

8. A method for manufacturing a touch display device, characterized in that: Include: Adhere a touch sensor to a first side of the front light guide module as claimed in claim 1 through a first adhesive layer; Adhere a reflective display to a second side of the front light guide module through a second adhesive layer, wherein the first side faces away from the second side; and A cover plate with a shielding layer is attached to the touch sensor through a third adhesive layer, so that the cover plate and the front light guide module are located on opposite sides of the touch sensor, wherein the shielding layer faces the touch sensor and contacts the third adhesive layer, and the thickness of the third adhesive layer is greater than the thickness of the first adhesive layer and greater than the thickness of the second adhesive layer.

9. The method for manufacturing a touch display device according to claim 8, wherein: The step of laminating the cover plate to the touch sensor is performed after the step of laminating the touch sensor and the reflective display to the front light guide module.

10. The method for manufacturing a touch display device according to claim 8, wherein: The thickness of the first adhesive layer and the thickness of the second adhesive layer are respectively 50 micrometers to 75 micrometers, and the thickness of the third adhesive layer is 100 micrometers to 125 micrometers.

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