TWI852234B - Electrode structure and device including the same - Google Patents

Abstract

An electrode structure includes a substrate and a silver nanowire electrode disposed on the substrate. The electrode structure can be changed from an unfolded state to a bent state with a bending radius of about 2-4 mm. The electrode structure includes a bending region and a first non-bending region and a second non-bending region respectively adjacent to the bending region in the bending state. The silver nanowire electrode has a change rate of a resistance value between the bent state and the unfolded state of 10% or less in an electrode section of the bending region.

Description

Electrode structure and device including the same

The present invention relates to an electrode structure and a device comprising the electrode structure, and in particular to an electrode structure in which the resistance variation rate of a bending section is controlled and a device comprising the electrode structure.

In recent years, flexible applications have gradually become a standard specification for electronic products. Compared with fixed-shape display devices, flexible display devices can be folded, rolled or bent to change the shape in the collapsed state, making them easier to carry and improving user convenience.

In order to evaluate the reliability of flexible devices in terminal use, dynamic bending tests are generally used. For example, Taiwan Patent Publication No. TW202221400 (hereinafter referred to as TW400) discloses a touch panel with SNW electrodes and peripheral metal traces, and measures the peripheral metal traces for dynamic bending tests at a specific curvature radius (for example, 200K times), and then measures the overall resistance change of the peripheral metal traces, but does not measure the resistance change of the SNW electrode in the bending area. In addition, U.S. Patent No. US11343911 (hereinafter referred to as US911) discloses a bending fixing device, which allows a transparent conductive electrode to be bent first and then fix its bending state. Although US911 discloses the change in resistance value of the transparent conductive electrode before and after bending, US911 measures the resistance value of the entire electrode. For example, as shown in FIG. 6 of US911, US911 measures the resistance value of the entire electrode with a length of 5 cm on both sides. The US911 is a fixed structure, not a flexible device. Users cannot switch between folded and undone states. Therefore, the resistance difference (or change) of the bending area is not a concern of the US911.

Flexible devices can be roughly divided into two types: external folding and internal folding. For external folding devices, users can view and touch the screen in the folded state. When users want to touch the screen in the bending area, whether the system can perform touch sensing normally will profoundly affect the user experience; on the other hand, users may switch from the unfolded state to the folded state and touch the screen at the same time (such as handwriting, gesture sliding, etc.). If the touch delay is felt when the finger slides to the folded area, it will also cause a poor experience. In summary, the touch performance of the folding area is a very important part of the user experience, and the key role is to ensure that the resistance of the touch electrode in the folding area does not produce a significantly large resistance change rate due to folding. Although the US911 is not a flexible device, from its public resistance data, it can be calculated that the resistance change rate of the US911 in the bending area exceeds 100%. In other words, in existing literature, due to the excessively high resistance change rate in the bending area, users experience delays and poor sensing when touching.

Therefore, in view of the above shortcomings, the present invention was created.

The object of the present invention is to provide an electrode structure, wherein the bending section of the electrode structure in a bent state has a resistance value variation rate of less than 10%, so that it has an excellent balance of conductivity and optical properties.

The electrode structure of the present invention comprises: a substrate; and a nanosilver wire electrode disposed on the substrate; wherein the electrode structure can change from an unfolded state to a bent state with a bending radius of about 2-4 mm, and the electrode structure has a bending region and first and second non-bending regions adjacent to the bending region in the bent state, respectively; the electrode segment of the nanosilver wire electrode in the bending region has a resistance value variation rate of less than 10% between the bent state and the unfolded state.

Preferably, according to the electrode structure of the present invention, the nanosilver wire electrode comprises nanosilver wires and resin.

Preferably, according to the electrode structure of the present invention, the electrode structure can be changed from an unfolded state to a bent state with a bending radius of about 3 mm, and the electrode segment of the nanosilver wire electrode in the bending area has a resistance value change rate between the bent state and the unfolded state of about 2.8%-7.2%; or the electrode structure can be changed from an unfolded state to a bent state with a bending radius of about 2-4 mm, and the electrode segment of the nanosilver wire electrode in the bending area has a resistance value change rate between the bent state and the unfolded state of about 2.4%-7.2%.

Preferably, according to the electrode structure of the present invention, the electrode structure can be changed from an unfolded state to a bent state with a bending radius of about 3 mm, and the electrode segment of the nanosilver wire electrode in the bending area has a resistance value change rate between the bent state and the unfolded state of about 2%-8%; or the electrode structure can be changed from an unfolded state to a bent state with a bending radius of about 2-4 mm, and the electrode segment of the nanosilver wire electrode in the bending area has a resistance value change rate between the bent state and the unfolded state of about 2%-8%.

Preferably, according to the electrode structure of the present invention, the nanosilver wire electrode has a first electrode and a second electrode, the first electrode and the second electrode are arranged on different sides of the substrate, the first electrode has a first resistance value change rate in the bent state and the unfolded state, the second electrode has a second resistance value change rate in the bent state and the unfolded state, and the first resistance value change rate is different from the second resistance value change rate.

Preferably, according to the electrode structure of the present invention, the nanosilver wire electrode has a first electrode and a second electrode, the first electrode and the second electrode are arranged on different sides of the substrate, and the second electrode is closer to the bending axis than the first electrode, the first electrode has a first resistance value change rate between the bent state and the unfolded state, and the second electrode has a second resistance value change rate between the bent state and the unfolded state, and the second resistance value change rate is greater than the first resistance value change rate.

Preferably, according to the electrode structure of the present invention, the nanosilver wire electrode has a first electrode and a second electrode, the first electrode and the second electrode are arranged on different sides of the substrate, and the second electrode is closer to the bending axis than the first electrode, the first electrode has a first resistance value change rate in a bent state with a bending radius of about 3 mm and the unfolded state, the second electrode has a second resistance value change rate in the bent state with a bending radius of about 3 mm and the unfolded state, the second resistance value change rate is about 1.1-2.5 times or 1.2-1.8 times the first resistance value change rate, and the second resistance value change rate and the first resistance value change rate are both less than 10%.

Preferably, according to the electrode structure of the present invention, the nanosilver wire electrode is made of nanosilver wire paste with a surface resistance between 15-100 ops; or the nanosilver wire electrode is made of nanosilver wire paste with a surface resistance of 30-70 ops, and the thickness of the nanosilver wire electrode is less than 50nm.

The present invention further provides a device, such as a display device, which includes the electrode structure as described above. The device is a flexible display device, which includes a display element, an optical glue layer is provided between the display element and the electrode structure, and the display element displays images corresponding to the bending area and the first and second non-bending areas.

Preferably, according to the device of the present invention, in the temperature range of -30°C to 60°C, the average slope of the energy storage modulus of the optical adhesive layer is between -4.0 kPa/°C and -1.5 kPa/°C.

In summary, the electrode structure provided by the present invention can provide users with a good touch experience when operating in a bent state. At the same time, the electrical and optical properties (such as transmittance and haze) of the electrode structure provided by the present invention in the bent state are within the product specification range.

In order to enable those skilled in the art to understand the purpose, features and effects of the present invention, the present invention is described in detail through the following specific embodiments in conjunction with the attached drawings.

The following will be described in more detail with reference to the attached drawings according to exemplary embodiments of the present invention, and the advantages, features and methods of achieving the present invention will be apparent. However, it should be noted that the present invention is not limited to the following exemplary embodiments, but can be implemented in various forms.

The terms used herein are only used to describe specific embodiments and are not intended to limit the present invention. Unless the context clearly indicates otherwise, the singular forms of the terms "a", "an" and "the" used herein also include plural forms.

In addition, it should be understood that spatial terms, such as: "beneath", "below", "under", "lower", "above", "upper", "over", "left side", "right side", "side", etc. may be used herein in correspondence with the spatial relationship in the figure to describe the relationship between one element and another element (or elements) as shown in the figure. In addition to the orientations depicted in the figure, the spatial terms herein may also cover different orientations of the device/apparatus/element in use, operation and/or manufacture. For example, if the device/apparatus/element in the figure is flipped, the elements described as being "below" or "beneath" other elements or features will be correspondingly considered to be "above" the other elements or features. Therefore, the term "below" described herein may include both above and below orientations depending on the spatial relationship of the device/apparatus/element. In addition, the device/device/element can be oriented in other ways (e.g., rotated 45 degrees, 90 degrees or in other orientations), that is, the spatial relative descriptors used in this article should be interpreted accordingly. In addition, if not explicitly stated in the text, the numerical values mentioned, such as thickness, width, line diameter, line length, etc., are not absolute but can be regarded as approximate values, that is, they have errors or ranges such as "about", "approximately" or "roughly". Those skilled in the art can understand that the numerical values referred to, such as thickness, width, line diameter, line length, etc., may include manufacturing tolerances, measurement errors, etc. The errors or ranges of the numerical values referred to in this article may be within plus or minus 20%, or within plus or minus 10%, or within plus or minus 5%.

It should also be understood that although the terms "first", "second", etc. may be used herein to describe various components, these components should not be limited to these terms. These terms are only used to distinguish between various components. Therefore, the first component in some embodiments may be referred to as the second component in other embodiments without departing from the teachings of the present invention. In this specification, the same reference numerals represent the same components.

Please refer to Figures 1 and 2. Figure 1 is a schematic diagram showing the electrode structure according to the present invention, which is an inductive touch electrode structure; Figure 2 is a cross-sectional view showing the electrode structure of Figure 1 in a bent state. Referring to Figure 1, the electrode structure 10 includes an electrode 12 and a substrate 11, and the substrate 11 can be used to support the electrode 12. In one embodiment, the electrode structure 10 can be combined with a transparent cover plate, a display module, an optical film, an optical glue, etc. (the above are not shown in Figure 1) to form a touch display device 100, and the touch display device 100 can be a bendable, foldable or other similar flexible display device (flexible display), as shown in Figures 3 and 4.

In this embodiment, the touch display device 100 includes a bending area BZ, however, the present invention should not be limited thereto. According to another embodiment of the present disclosure, the touch display device 100 may include a plurality of folding areas. The touch display device 100 may include a display area DA and a peripheral area PA located on the side of the display area DA, and the electrode structure 10 of the embodiment of the present invention substantially corresponds to the display area DA, so that the user can view the display screen and perform touch operations.

For simplicity, FIG1 and FIG2 only depict the electrode structure. Referring to FIG2, the electrode structure 10 of the embodiment of the present invention includes a bending zone BZ, that is, the electrode 12 and the substrate 11 can be bent and folded in the bending zone BZ. As shown in FIG2, the electrode structure 10 can be folded along the axis FX1 extending in a predetermined direction, and the embodiment of the present invention defines the bending radius RR as the distance from the projection position of the axis FX1 in the vertical direction to the lower surface of the substrate 11. In this article, this folded state can be referred to as a "folded state" or a "bent state". FIG1 shows the state of the electrode structure 10 when it is unfolded, that is, the state that is not bent can be referred to as an "unfolded state", "unfolded state" or "unbent state". In addition, FIG1 shows that the electrode structure 10 includes a bending zone BZ, but the present invention is not limited to this, that is, the electrode structure 10 may include multiple bending zones BZ. The electrode structure 10 of the embodiment of the present invention may define multiple areas according to the operating mode of the electronic product, for example, may include at least one of the bending zone BZ and the non-bending zone FZ. As shown in FIG1, the bending zone BZ may be confined between two non-bending zones FZ. In other embodiments, the touch display device may have a bending zone BZ and a non-bending zone FZ.

In another embodiment, the electrode structure 10 of the present invention can be combined with a transparent cover plate, a display module, an optical film, an optical glue, etc. (not shown in FIG. 1 ) to form a touch display device, and the touch display device can be a rollable touch display device. When the device is rolled up, the entire display device forms a single bending area BZ.

In some embodiments, the substrate 11 may be, but is not limited to, a glass substrate (e.g., a bendable ultra-thin glass substrate), a polyethylene terephthalate (PET) substrate, a cycloolefin polymer (COP) substrate, a transparent polyimide (CPI) substrate, a polyethylene naphthalate (PEN) substrate, a polycarbonate (PC) substrate, a polyether sulfide (PES) substrate, etc.; in addition, the substrate 11 may have the function of carrying an electrode, and may also provide an optical function as required, for example, the substrate 11 may be a phase difference film, a compensation film, a polarizing film, an anti-glare film, an anti-reflection film, or a combination thereof, etc.; or other functional films, such as a protective film, an anti-scratch film, an anti-fouling film, or a combination thereof, etc., or a composite functional film of the above.

Specifically, referring to FIG. 1 , the electrode 12 is disposed on the substrate 11. In some embodiments, the electrode 12 includes a touch electrode layer disposed on the substrate 11. According to some embodiments, the touch electrode layer can be a transparent conductive material, including a material selected from metal oxides, such as indium tin oxide (ITO), or metal mesh, silver nanowire (SNW), carbon nanotube (CNT), graphene, or conductive polymers such as poly (3,4-ethylenedioxythiophene) (PEDOT), etc., and in particular, the touch electrode layer can be formed using one or more of these materials.

More specifically, in one embodiment, the electrode 12 is made of silver nanowires, and the method used may be to coat a dispersion containing silver nanowires on the substrate 11, for example, mixing the silver nanowires into a solvent, such as water, alcohol, ketone, ether, hydrocarbon or aromatic solvent (benzene, toluene, xylene, etc.) to form a coating/slurry; the coating/slurry may also include additives, surfactants or binders, such as carboxymethyl cellulose (CMC), 2-hydroxyethyl cellulose (HEC), hydroxypropyl methylcellulose (HPMC), sulfonates, sulfates, disulfonates, sulfosuccinates, phosphates or fluorine-containing surfactants, etc.

More specifically, the term "metal nanowires" as used herein is a collective term, which refers to a collection of metal wires comprising a plurality of elemental metals, metal alloys or metal compounds (including metal oxides), wherein the number of metal nanowires contained therein does not affect the scope of protection claimed by the present invention; and at least one cross-sectional dimension (i.e., the diameter of the cross section) of a single metal nanowire is less than about 500 nm, preferably less than about 100 nm, and more preferably less than about 50 nm; and the metal nanostructure referred to as "wire" in the present invention mainly has a high aspect ratio, for example, between about 10 and 100,000. More specifically, the aspect ratio (ratio of wire length to cross-sectional diameter) of the metal nanowire may be greater than about 10, preferably greater than about 50, and more preferably greater than about 100; the metal nanowire may be any metal, including (but not limited to) silver, gold, copper, nickel, and gold-plated silver. Other terms, such as silk, fiber, tube, etc., if they also have the above-mentioned size and high aspect ratio, are also covered by the present invention. Considering that the parameters of the silver nanowires contained in the dispersion used for coating are not completely the same, for example, the silver nanowires produced in different production batches with the same specifications may have different average diameters (i.e., wire diameters), diameter standard deviations, maximum/minimum diameters, diameter distributions, etc., or different average wire lengths, wire length standard deviations, maximum/minimum wire lengths, wire length distributions, etc., the distribution of metal nanowires can be referred to US20110174190, and the entire text is introduced into the embodiments of the present invention. Therefore, in order to avoid the electrodes made of the same specification of nano silver wire slurry having different resistance value changes in the bending area, the embodiment of the present invention requires that the resistance value changes of the electrodes in the bending area be limited to less than about 15%, 12%, 10%, and 8% according to mass production and product acceptance standards.

In a preferred embodiment, the shape of the nanostructure is anisotropic (i.e., aspect ratio ≠ 1). Anisotropic nanostructures typically have a longitudinal axis along their length. Exemplary anisotropic nanostructures may include nanowires, i.e., solid nanowire structures having an aspect ratio (ratio of wire length to wire diameter) of at least 10 and more typically at least 50. A nanowire population of a specific specification (e.g., a product after synthesis and purification or a coating/slurry formed by mixing with a solvent) does not have a uniform size, but includes nanostructures within a certain size (wire length, wire diameter, etc.) range. Therefore, the specifications of a film formed by such a nanowire population (e.g., optical properties, electrical properties, or flexibility properties after being subjected to force) depend on the combined effect of the entire nanowire population.

After coating, a curing step is performed to form a nanosilver wire layer, and the nanosilver wire layer can be used to form the electrode 12 using a patterning method known to those skilled in the art (e.g., using a photolithography process of photoresist in combination with laser etching or etching liquid etching process, etc.).

Preferably, in one embodiment, a polymer layer can be further provided so that the polymer layer covers the nanosilver wire layer, so the polymer layer can be called an overcoat (OC). In a specific embodiment, a suitable polymer/polymer is coated on the nanosilver wire layer, and the polymer with a flow state/property can penetrate between the nanosilver wires to form a filler, so the polymer layer can also be called a matrix layer (matrix), and the nanosilver wires will be embedded in the polymer/polymer, and after the polymer is solidified, a composite structure of silver wire-resin is formed. That is, in this step, a polymer/polymer-added polymer layer is coated on the silver nanowire layer, and the silver nanowire is embedded in the polymer layer to form a composite structure. In some embodiments of the present invention, the polymer layer is formed of an insulating material. For example, the material of the polymer layer can be a non-conductive resin or other organic material, such as polyacrylate, epoxy resin, polyurethane, polysilane, polysilicon, poly(silicon-acrylic acid), polyethylene (PE), polypropylene (PP), polyvinyl butyral (PVB), polycarbonate (PC), acrylonitrile-butadiene-styrene (ABS), etc. In some embodiments of the present invention, the polymer layer can be formed by spin coating, spray coating, printing, etc. In some embodiments of the present invention, the thickness of the polymer layer is about 20nm to 10mm, or 50nm to 200nm, or 30nm to 100nm. For example, the thickness of the polymer layer can be about 90nm or 100nm. The above-mentioned specific methods can refer to and fully introduce US20190227650A, CN101292362 and other documents, and the nanosilver wire slurry and polymer coating are provided by the supplier Cambrios. If not specifically stated, the nanosilver wire electrode referred to in this article is a composite structure conductive layer of silver wire/resin. In some embodiments, the thickness of the nanosilver wire electrode with a surface resistance of 30ops (Ω/square) may be less than 50nm, or between 10nm-50nm, 20nm-40nm, or 40nm-50nm. Under this surface resistance, if the thickness of the nanosilver wire electrode is too large (for example, greater than 50nm), it may cause the optical performance of the nanosilver wire electrode (for example, yellowness b* value) to be difficult to meet the requirements, and may cause the contact impedance between the nanosilver wire electrode and the subsequently arranged material layer (for example, the peripheral area conductor using metal material) to be higher; if the thickness of the nanosilver wire electrode is too small (for example, less than 10nm), it may cause the nanosilver wire electrode to have insufficient anti-ultraviolet light performance.

Specifically, according to some embodiments, the electrode structure 10 may further include an isolation layer or a protective layer, and the isolation layer is disposed above the nanosilver wire layer or the nanosilver wire/resin composite structure layer. In the present invention, the term "isolation" covers both electrical isolation and physical isolation. The isolation layer may be a single layer or a multi-layer stack of an inorganic packaging material, or a stack of an inorganic packaging material and an organic packaging material. The inorganic packaging material used is, for example but not limited to, silicon nitride ( _SiNx ), silicon oxide ( _SiOx ), silicon oxynitride ( _SiONx ), aluminum oxide ( _AlOx ), or titanium oxide ( _TiOx ).

The specific method of the electrode structure of the first embodiment of the present invention is as follows:

S1: Provide a substrate 11, which is a 50µm thick PET substrate (product model U483) provided by Toray Corporation.

S2: Setting a transparent conductive film. The nanosilver wire slurry (product model G6, surface resistance specification: 30 ops (Ω/square), the aspect ratio of the nanowire is between about 450-550) and the polymer coating (product model OCHE) provided by Cambrios are sequentially formed on the substrate 11 by roll-to-roll coating, and cured to form a nanosilver wire layer with a thickness of about 30nm.

S3: forming a touch electrode. The nanosilver wire layer is formed into an electrode with a specific pattern (such as a plurality of axial touch electrodes 121 shown in FIG. 5 ) by laser etching, thus completing the electrode structure 10 of the embodiment of the present invention. In addition, the ab segment of the electrode in the bending region BZ is defined (i.e., point a is substantially located at the boundary/interface between the bending region BZ and the non-bending region FZ; point b is substantially located at the boundary/interface between the bending region BZ and another non-bending region FZ), and point c and point d are the two end points of the entire axial touch electrode 121; the length of the cd segment is about 10 mm, the length of the ab segment is about 1 mm, and the width of the axial touch electrode 121 is about 10µm.

S4: Measure the change in resistance (line resistance) of the ab section of the touch electrode 121 in the bent state. First, connection points are set at point a and point b of the touch electrode, for example, conductive silver slurry is set at point a and point b, and then the probe of the resistance measurement equipment can be connected to the conductive silver slurry to measure the resistance of the ab section. Accordingly, the resistance values of the ab section and the cd section are measured in a bent state (the electrode structure 10 of the embodiment of the present invention is folded 180 degrees with a bending radius of 3 mm, as shown in the schematic diagram of FIG. 2 ) and an unbent state.

The specific method of the electrode structure of the second embodiment of the present invention is the same as that of the first embodiment, except that different batches of nano silver wire slurry are used.

The specific method of the electrode structure of the third embodiment of the present invention is the same as that of the first embodiment, except that a nano-silver wire slurry of a different product specification is used. This embodiment uses a nano-silver wire slurry of Cambrios product model G6 with a surface resistance specification of 70 ops.

The specific method of the electrode structure of the fourth embodiment of the present invention is the same as that of the third embodiment, except that the bending condition is changed to folding 180 degrees with a bending radius of 2 mm.

The specific method of the electrode structure of the fifth embodiment of the present invention is the same as that of the third embodiment, except that the bending condition is changed to folding 180 degrees with a bending radius of 4 mm.

The specific method of the electrode structure of the sixth embodiment of the present invention is the same as that of the first embodiment, except that the substrate 11 is changed to a PET substrate with a thickness of 125 μm provided by Toray Corporation (product model U483).

The specific method of the electrode structure of the seventh embodiment of the present invention is the same as that of the first embodiment, except that the substrate 11 is changed to a PET substrate with a thickness of 125µm provided by Toray Corporation (product model U483); at the same time, nano-silver wire slurry of different product specifications is also used. This embodiment uses Cambrios product model G5, surface resistance specification: 30 ops, and aspect ratio of nano-silver wire slurry between about 400-750.

According to the embodiment of the present invention, since the touch electrode generates a resistance change in the ab section of the bending zone BZ, for the computing element (such as a touch chip), an excessive resistance change will cause a delay in signal transmission, resulting in a low touch reporting rate or poor touch sensing. In one embodiment, when the touch electrode is applied to an outward-folding electronic product (i.e., when the device is folded, the user can still view and touch the display screen), if the resistance value change of the touch electrode in the ab section of the bending zone BZ exceeds the specification of the computing element (for example, greater than 15%, 12%, 10%), the above-mentioned problem will occur. Accordingly, the embodiment of the present invention can meet the specifications of the computing element (for example, the resistance value change of the touch electrode in the ab section of the bending zone BZ can be less than 15%, 12%, 10%, 8%) to meet the use of outward-folding electronic products. Table 1 below shows the results of the touch sensing simulation of the electrodes made in the above-mentioned embodiments, in which the electrode of the second embodiment has a poor touch sensing effect. Although the resistance value change rate presented in Table 1 is a positive number, the present invention does not exclude the state of the resistance value change rate being a negative number. In other words, as long as the absolute value of the resistance value change rate conforms to the content set forth herein, it belongs to the scope of the present invention.

Table 1 Resistance value change rate (%) Touch Sensing Simulation First Embodiment 4.2 O Second Embodiment 11.7 Δ Third Embodiment 2.8 O Fourth embodiment 3.1 O Fifth embodiment 2.4 O Sixth embodiment 7.2 O Seventh embodiment 6.9 O

Combining the first and second embodiments, it is found that electrodes made of nanosilver wires of the same specification but different batches will have different changes in resistance after bending, and the electrode of the second embodiment has a problem of delayed reporting when performing touch sensing simulation (i.e., represented by "Δ" in Table 1). As mentioned above, although the common performance of each batch of nanosilver wire slurry is consistent, there are still differences in individual silver wire specifications between each batch, so it is necessary to give specifications based on the characteristics of the electrode to ensure that the inspection of the terminal product meets the specifications.

Combining the first and third embodiments, the use of high-resistance nanosilver wire slurry will result in a smaller resistance value variation rate (%). The reason for this is that the high-resistance nanosilver wire slurry will form an electrode with a higher resistance value after coating, so the resistance value variation caused by the electrode in the bending area will not result in a large resistance value variation rate (%). However, from the perspective of signal transmission, an electrode with a high resistance value is not preferred; therefore, although a nanosilver wire paste with a high surface resistance helps to achieve a smaller resistance value variation rate (%), from the perspective of signal transmission of the entire electrode, the embodiment of the present invention recommends using a nanosilver wire paste with a surface resistance less than 100 ops, preferably a nanosilver wire paste with a surface resistance less than 85 ops, or a nanosilver wire paste with a surface resistance less than 70 ops.

Similarly, from the analysis of the first and third embodiments, the use of a nano-silver wire paste with a low surface resistance may lead to a higher resistance value variation rate (%), and from an optical point of view, the nano-silver wire paste with a low surface resistance may also cause poor optical properties (such as increased haze) due to the presence of more nano-silver wire components; therefore, the embodiment of the present invention recommends the use of a nano-silver wire paste with a surface resistance greater than 15 ops, preferably a nano-silver wire paste greater than 20 ops, or a nano-silver wire paste greater than 30 ops. In summary, in order to make the resistance value change of the touch electrode in the ab section of the bending area BZ not exceed the specifications of the computing element, and to have good optical properties (for example, haze less than 1) and signal transmission characteristics, a nanosilver wire paste with a surface resistance between 15-100 ops, or a nanosilver wire paste with a surface resistance between 20-85 ops, or a nanosilver wire paste with a surface resistance between 30-70 ops can be selected. In the first embodiment, the conductive film made of the nanosilver wire paste with a surface resistance of 30 ops has a haze between 0.4-0.6; in the third embodiment, the conductive film made of the nanosilver wire paste with a surface resistance of 70 ops has a haze between 0.25-0.3.

Combining the first and sixth embodiments, when a thicker substrate is used, it can be understood that the nano silver wire electrode has a larger strain in the bending zone. According to the mechanical simulation system, the strain of the electrode in the bending zone of the first and sixth embodiments is 0.56% and 1.91%, respectively. In other words, the use of a thicker substrate will cause the electrode to have a larger strain in the bending zone, thereby producing a larger resistance value change rate in the bending zone. If the strain and the resistance value change rate of the electrode in the bending zone are considered to be proportional, it can be expected that when the strain is greater than 2.76%, the use of the silver wire of the first embodiment may cause the resistance value change rate of the electrode in the bending zone to exceed 10%. On the other hand, when a thicker substrate is used, it can be known from the mechanical theory that when the film layer is bent under force, a tensile stress zone and a compressive stress zone will be generated, and a neutral axis/neutral surface (neutral surface; refer to "Mechanics of Materials" by James M. Gere et al .) with zero force will be formed between the two zones. Therefore, the first and sixth embodiments are used to illustrate that when the substrate is thicker (i.e., the sixth embodiment), when the entire stack is bent under force, the position of the electrode will be farther away from the neutral axis (compared with the first embodiment), so that the electrode of the sixth embodiment has a larger stress/strain in the bending zone, thereby generating a larger resistance value change rate in the bending zone. According to the above-mentioned neutral axis point of view, when a thicker substrate is selected, it is possible to consider adding other film layers on top of the nanosilver wire electrode, such as a protective layer, a glue layer, an optical film layer, etc., to move the position of the neutral axis upward, that is, to make the nanosilver wire electrode closer to the neutral axis, so as to reduce the stress/strain of the electrode in the bending area, thereby achieving a resistance value change rate of no more than 10%.

In addition, in the bent state, the change in the resistance value of the cd section will also affect the sensitivity of the touch sensing. In the first embodiment, the change in the resistance value of the cd section is approximately between 1-5%.

The electrode structure of another embodiment of the present invention is to set the touch electrode on both sides (such as the upper and lower sides) of the substrate 11. For example, as shown in Figure 6, the second electrode 12B (such as the driving electrode) is set on the lower side of the substrate 11, and the first electrode 12A (such as the sensing electrode) is set on the upper side of the substrate 11. The first electrode 12A and the second electrode 12B can be formed using the method described above. In the bent state, both the first electrode 12A and the second electrode 12B must meet the requirement that the resistance value change rate does not exceed 10%; on the other hand, since the distances from the first electrode 12A and the second electrode 12B to the axis FX1 are different, under the same bending conditions, the strains received by the first electrode 12A and the second electrode 12B are different. Therefore, it can be seen that the resistance value change rates of the first electrode 12A and the second electrode 12B under the same bending conditions are different. In this embodiment, since the distance between the first electrode 12A and the axis FX1 is farther than the distance between the second electrode 12B and the axis FX1 (equivalent to a larger bending radius of the first electrode 12A), the second electrode 12B is subjected to a larger stress, and thus the resistance value variation rate of the second electrode 12B is greater than the resistance value variation rate of the first electrode 12A (but both meet the requirement of not exceeding 10%). From the analysis of the first and sixth embodiments, under the condition of a bending radius of 3 mm, the resistance value variation rate of the second electrode 12B is about 1.1-2.5 times or 1.2-1.8 times the resistance value variation rate of the first electrode 12A.

The eighth embodiment of the present invention is to manufacture the electrode 12 on a 25µm thick cycloolefin copolymer (COP) substrate provided by the supplier KONICA MINOLTA, and then bond it with a 50µm transparent polyimide film (Colorless PI, CPI) through an optical adhesive layer, and perform a bending test with a bending radius of 3mm. In this embodiment, the CPI substrate is used to simulate a display element, such as an organic light-emitting diode display (OLED). In this embodiment, the resistance value change rate of the electrode 12 meets the aforementioned specifications.

In addition, the energy storage modulus and bending test results measured by dynamic load tests at different temperatures show that the average slope of the energy storage modulus of the optical adhesive layer (-30°C to 60°C) must be between -4.0 kPa/℃ and -1.5 kPa/℃ to have sufficient stability (that is, the adhesive properties will not change significantly due to temperature changes) and good product reliability.

As shown in Table 2, various optical adhesive layers were tested in this embodiment of the present invention. Sample 1 Sample 2 Sample 3 Sample 4 Average slope of storage modulus (kPa/℃) -1.7 -2.8 -3.8 -43.3

It can be seen from this embodiment that the greater the absolute value of the average slope of the storage modulus (for example, the absolute value of the average slope of the storage modulus of sample 4 is estimated to be 10 times that of the other three samples), the greater the variability of the storage modulus from -30°C to 60°C. Therefore, the storage modulus of sample 4 at high temperature (such as 60°C) is too small, and the material softens quickly within the temperature range, which is highly fluid (the material strength is low, and the internal polymerization/crystallization force is very small), which is not conducive to engineering applications. Specifically, the material strength of sample 4 at high temperature (such as 60°C) is not conducive to the actual production process; and in the bent state, due to the low material strength of sample 4, it is possible to cause stress to be concentrated on the electrode 12, and thus fail to meet the aforementioned resistance value variation rate requirements.

In contrast, if the average slope absolute value of the energy storage modulus is too small, for example, less than 1.5 (-1.5 absolute value), although the energy storage modulus variability is small within the temperature range (-30°C to 60°C), the energy storage modulus of the material at high temperature is too large. An excessively large energy storage modulus means that the adhesive material is hard and has poor viscosity, so delamination/bubbling occurs under high-temperature bending tests. The delamination/bubbling caused by bending may cause the electrode 12 to be destroyed at the same time (i.e., the aforementioned resistance value variation rate requirement cannot be met), which will lead to poor product reliability.

In summary, the embodiments of the present invention can use an optical adhesive with an average slope of the energy storage modulus (-30°C to 60°C) between -4.0 kPa/℃ and -1.5 kPa/℃ or between -3.8 kPa/℃ and -1.7 kPa/℃ to bond components such as a transparent cover plate, a display module, and an optical film to form a touch display device. At the same time, the touch display device can meet the aforementioned resistance value change rate requirement when bent.

It is understandable that a person having ordinary knowledge in the technical field to which the present invention belongs can make various changes and modifications based on the above examples, which are not listed one by one here.

Finally, the technical features of the present invention and the technical effects that can be achieved are summarized as follows:

1. According to the embodiment of the present invention, when the transparent electrode is in a bent state (without limiting the bending conditions), the resistance value variation rate of the line segment located in the bending area is less than 10%, so that the user has a good touch experience when operating in the bent state.

2. According to the embodiments of the present invention, when the transparent electrode is in a bent state (the bending radius is between about 2-4 mm or the bending radius is about 2, 3 or 4 mm), the resistance value variation rate of the line segment located in the bending area is between 2%-8% or 2.4%-7.2%, and the electrical and optical properties (such as transmittance and haze) of the transparent electrode are within the product specification range.

3. According to the embodiment of the present invention, when the transparent electrode is bent with a bending radius of about 3 mm, the resistance value variation rate of the line segment located in the bending area is between 2%-8% or 2.8%-7.2%. At the same time, the electrical and optical properties (such as transmittance and haze) of the transparent electrode are within the product specification range.

The above describes the implementation of the present invention by using specific embodiments. A person having ordinary knowledge in the relevant technical field can easily understand the technical features, advantages, and effects of the present invention from the contents disclosed in this specification.

The above is only a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Any other equivalent changes or modifications that are completed without departing from the spirit disclosed by the present invention should be included in the scope of the following patent application.

10: Electrode structure 11: Substrate 12: Electrode 12A: First electrode 12B: Second electrode 100: Touch display device 121: Touch electrode a, b, c, d: Points BZ: Bending area DA: Display area FX1: Axis FZ: Non-bending area PA: Peripheral area RR: Bending radius

FIG1 is a schematic diagram of an electrode structure according to an embodiment of the present invention; FIG2 is a cross-sectional view showing a bent state of the electrode structure shown in FIG1; FIG3 is a stereoscopic view of a touch display device according to the present invention; FIG4 is a stereoscopic view showing a bent state of the touch display device shown in FIG3; FIG5 is a schematic diagram of a pattern of an electrode structure according to the present invention; and FIG6 is a cross-sectional view showing a bent state of an electrode structure of another embodiment of the present invention.

10: Electrode structure 11: Substrate 12: Electrode BZ: Bending zone FX1: Axis FZ: Non-bending zone RR: Bending radius

Claims (14)

An electrode structure includes: a substrate; and a nanosilver wire electrode disposed on the substrate; wherein the electrode structure can change from an unfolded state to a bent state with a bending radius of about 2-4 mm, and the electrode structure has a bending region and first and second non-bending regions adjacent to the bending region in the bent state, respectively; the electrode segment of the nanosilver wire electrode in the bending region has a resistance value change rate of less than 10% between the bent state and the unfolded state. The electrode structure as described in claim 1, wherein the nanosilver wire electrode comprises nanosilver wires and resin. The electrode structure as described in claim 1, wherein the electrode structure can be changed from an unfolded state to a bent state with a bending radius of about 3 mm, and the resistance value change rate of the electrode segment of the nanosilver wire electrode in the bending area between the bent state and the unfolded state is between about 2.8% and 7.2%. The electrode structure as described in claim 1, wherein the electrode structure can be changed from an unfolded state to a bent state with a bending radius of about 2-4 mm, and the resistance value change rate of the electrode segment of the nanosilver wire electrode in the bending area between the bent state and the unfolded state is between about 2.4%-7.2%. The electrode structure as described in claim 1, wherein the electrode structure can be changed from an unfolded state to a bent state with a bending radius of about 3 mm, and the resistance value change rate of the electrode segment of the nanosilver wire electrode in the bending area between the bent state and the unfolded state is between about 2% and 8%. The electrode structure as described in claim 1, wherein the electrode structure can be changed from an unfolded state to a bent state with a bending radius of about 2-4 mm, and the resistance value change rate of the electrode segment of the nanosilver wire electrode in the bending area between the bent state and the unfolded state is between about 2%-8%. The electrode structure as described in claim 1, wherein the nanosilver wire electrode has a first electrode and a second electrode, the first electrode and the second electrode are arranged on different sides of the substrate, the first electrode has a first resistance value change rate in the bent state and the unfolded state, the second electrode has a second resistance value change rate in the bent state and the unfolded state, and the first resistance value change rate is different from the second resistance value change rate. The electrode structure as described in claim 1, wherein the nanosilver wire electrode has a first electrode and a second electrode, the first electrode and the second electrode are arranged on different sides of the substrate, and the second electrode is closer to the bending axis than the first electrode, the first electrode has a first resistance value change rate in the bent state and the unfolded state, and the second electrode has a second resistance value change rate in the bent state and the unfolded state, and the second resistance value change rate is greater than the first resistance value change rate. The electrode structure as described in claim 1, wherein the nanosilver wire electrode has a first electrode and a second electrode, the first electrode and the second electrode are arranged on different sides of the substrate, and the second electrode is closer to the bending axis than the first electrode, the first electrode has a first resistance value change rate in the bent state with a bending radius of about 3 mm and the unfolded state, the second electrode has a second resistance value change rate in the bent state with a bending radius of about 3 mm and the unfolded state, the second resistance value change rate is about 1.1-2.5 times the first resistance value change rate, and the second resistance value change rate and the first resistance value change rate are both less than 10%. The electrode structure as described in claim 1, wherein the nanosilver wire electrode has a first electrode and a second electrode, the first electrode and the second electrode are arranged on different sides of the substrate, and the second electrode is closer to the bending axis than the first electrode, the first electrode has a first resistance value change rate in the bent state with a bending radius of about 3 mm and the unfolded state, the second electrode has a second resistance value change rate in the bent state with a bending radius of about 3 mm and the unfolded state, the second resistance value change rate is about 1.2-1.8 times the first resistance value change rate, and the second resistance value change rate and the first resistance value change rate are both less than 10%. The electrode structure as described in claim 1, wherein the nanosilver wire electrode is made of nanosilver wire slurry with a surface resistance between 15-100 ops, and the thickness of the nanosilver wire electrode is less than 50nm. The electrode structure as described in claim 1, wherein the nanosilver wire electrode is made of nanosilver wire slurry with a surface resistance of 30-70ops, and the thickness of the nanosilver wire electrode is less than 50nm. A device comprising an electrode structure as described in claim 1, wherein the device is a flexible display device, the flexible display device includes a display element, an optical adhesive layer is provided between the display element and the electrode structure, and the display element displays images corresponding to the bending area and the first and second non-bending areas. The device as described in claim 13, wherein in the temperature range of -30°C to 60°C, the average slope of the energy storage modulus of the optical adhesive layer is between -4.0 kPa/°C and -1.5 kPa/°C.

Images