Capacitive touch screen

Abstract

The utility model belongs to the field of touch display, and particularly relates to a capacitive touch screen, in particular to a capacitive touch screen based on a TAC base material. A capacitive touch screen includes: a display module; the polaroid is arranged on the upper portion of the display module; the touch screen comprises a display module and a polaroid, the polaroid is arranged on the display module, the touch sensor is arranged between the polaroid and the display module, the touch sensor comprises a metal grid circuit pattern, and the metal grid circuit pattern is composed of a copper layer and an alloy layer. According to the capacitive touch screen provided by the embodiment of the invention, an additional barrier layer or blackening layer is not needed, through the collaborative design of the thicknesses and the positions of the copper layer and the alloy layer, an iodide ion permeation path is blocked while the conductivity is guaranteed, the corrosion resistance is improved, and light and thin effects are realized.

Description

Technical Field

[0001] This application belongs to the field of touch display, specifically relating to a capacitive touch screen, and more particularly to a capacitive touch screen based on a TAC substrate. Background Technology

[0002] Currently, OLED touch display panels offer superior display performance and flexibility, leading to their increasingly widespread use in devices such as smartphones, tablets, and computers. However, due to the structural characteristics of OLED devices, reflection of ambient light can severely degrade optical parameters such as display contrast. To address this issue, a polarizer is typically used between the cover glass and the OLED display panel to block reflected light from escaping.

[0003] Similarly, for traditional LCD touch display panels, in order to solve the problems of degraded display effect of traditional external touch and the inflexibility and high cost of in-cell touch, there is also a current approach of placing the touch sensor under the upper polarizer.

[0004] Both products were found to have a serious problem during reliability testing: the polarizer corroded the circuit pattern of the touch sensor, causing the touch function to fail.

[0005] BOE Technology Group has applied for patent CN2020110473168 in response to this issue, proposing an improvement by setting a barrier layer on the side of the phase retardation layer away from the linear polarization layer. By setting a barrier layer on the side of the linear polarization layer closer to the touch display panel, acidic substances in the linear polarization layer can be prevented from penetrating into the touch display panel, thereby avoiding corrosion of the touch metal lines. However, this solution requires an additional barrier layer, which reduces the product's transmittance and increases haze, degrading product performance. Furthermore, adding a barrier layer also increases the product thickness, which does not conform to the development trend of lightweight, thin, and flexible electronic products.

[0006] There is also a patent application (CN2018105976028) filed by Truly Optoelectronics, which proposes an improvement by using a blackened Cu alloy mesh layer containing copper oxide, copper nitride, and other oxides. This alloy mesh layer contains one or two of copper oxide, copper nitride, aluminum oxide, and zinc oxide. It forms a dense oxide film using aluminum oxide or zinc oxide to isolate moisture, thereby improving the reliability of the film layer. However, while this solution offers better protection against moisture corrosion than traditional metal meshes such as pure copper, pure copper + copper oxide, and pure copper + copper nitride, it is not very effective against the acidic iodine ions present in the polarizer. Iodine ions attack the passivation films of copper oxide, copper nitride, aluminum oxide, and zinc oxide, generating water-soluble iodides. This corrosion is particularly accelerated in high-temperature and high-humidity environments, leading to the corrosion and failure of the metal mesh. Utility Model Content

[0007] In order to overcome the shortcomings of the prior art, this application proposes to provide a capacitive touch screen that does not require an additional barrier layer or blackening layer. By coordinating the thickness and position of the copper layer and the alloy layer, it can block the iodine ion penetration path while ensuring conductivity, thereby improving corrosion resistance and achieving a thinner and lighter design.

[0008] This application discloses a technical solution: a capacitive touchscreen, comprising:

[0009] Display module;

[0010] A polarizer, wherein the polarizer is disposed above the display module; and,

[0011] A touch sensor is disposed between the polarizer and the display module. The touch sensor includes a metal mesh circuit pattern, which is composed of a copper layer and an alloy layer.

[0012] Furthermore, this application also discloses that the thickness of the copper layer is 0-1 μm.

[0013] Furthermore, this application also discloses that the thickness of the copper layer is 0.3-0.8 μm.

[0014] Furthermore, this application also discloses that the thickness of the alloy layer is 0.1-1 μm, and that the alloy layer is located on the side close to the polarizer.

[0015] Furthermore, this application also discloses that the alloy layer is a copper-nickel-titanium alloy, with the total mass percentage of copper, nickel and titanium being 100%, the mass fraction of copper being 50%-95%, the mass fraction of nickel being 4.9%-45%, and the mass fraction of titanium being 0.1%-5%.

[0016] Furthermore, this application also discloses that the touch sensor has a double-sided structure, including an upper electrode and a lower electrode, which are separated by a transparent base film.

[0017] Furthermore, this application also discloses that the transparent base film is a TAC film.

[0018] Compared with the prior art, this application achieves at least the following technical effects:

[0019] 1. The touch sensor in this application is located between the polarizer and the display module, avoiding the problem of external light reflection and eliminating the need for a blackening layer; the touch failure problem caused by iodine ion corrosion of the metal mesh circuit is solved through the structural synergistic design of the copper layer and the alloy layer.

[0020] 2. This application adopts a double-layer metal mesh design. The copper layer (thickness 0-1μm) is located away from the polarizer side and provides high conductivity. The alloy layer (thickness 0.1-1μm) is located close to the polarizer side, covering the surface of the copper layer and blocking the penetration of iodine ions. The alloy layer is located between the copper layer and the polarizer, forming a physical isolation barrier.

[0021] 3. Alloy layer of this application: such as the density and low activity of copper-nickel-titanium alloy, combined with the thickness and position design, to block the diffusion path of iodine ions to the copper layer. After high temperature and high humidity test (85℃ / 85%RH, 240h), the resistance change rate is <5% (traditional solution >50%), and the corrosion resistance is improved.

[0022] 4. This application eliminates the barrier layer and blackening layer, reducing the total thickness by 0.5-15um, and reducing the transmittance by more than 1% compared to the traditional solution;

[0023] 5. The copper layer and alloy layer of this application can be completed by the same sputtering equipment. Only the last sputtering copper target needs to be changed to a copper-nickel-titanium alloy target. No new equipment or additional processes are required, and the production cost is reduced by 5-10%. Attached Figure Description

[0024] Figure 1 : A schematic diagram of the capacitive touchscreen structure of this application;

[0025] In the figure: 200. Touch sensor; 210. Lower electrode of touch sensor; 220. Transparent base film; 230. Upper electrode of touch sensor; 240. Alloy layer; 300. First OCA optical adhesive; 400. Polarizing film; 500. Second OCA optical adhesive; 600. Display module. Detailed Implementation

[0026] The embodiments described in this application are further illustrated in conjunction with the accompanying drawings.

[0027] A capacitive touchscreen includes: a display module 600; a polarizer 400 disposed above the display module 600; and a touch sensor 200 disposed between the polarizer 400 and the display module 600, the touch sensor 200 including a metal mesh circuit pattern composed of a copper layer and an alloy layer 240.

[0028] The thickness of the copper layer is 0-1 μm. An excessively thick copper layer (>1 μm) results in decreased flexibility, while an excessively thin layer (<0.1 μm) leads to insufficient conductivity.

[0029] The alloy layer 240 has a thickness of 0.1-1 μm and is located on the side close to the polarizer 400. When the thickness of the alloy layer 240 is <0.1 μm, it cannot effectively block the corrosive medium. The alloy layer 240, as a "sacrificial layer", preferentially contacts the iodine ions released by the polarizer 400 to protect the inner copper layer. The copper layer and the alloy layer 240 are integrally formed by sputtering process to avoid corrosion penetration caused by interlayer peeling.

[0030] The alloy layer 240 is a copper-nickel-titanium alloy, with the total mass percentage of copper, nickel, and titanium being 100%, the mass fraction of copper being 50%-95%, the mass fraction of nickel being 4.9%-45%, and the mass fraction of titanium being 0.1%-5%.

[0031] The touch sensor 200 has a double-sided structure, including an upper electrode 230 and a lower electrode 210, which are separated by a transparent base film 220.

[0032] The transparent base film 220 is a TAC film. TAC film, short for triacetyl cellulose film, is a high-performance optical thin film material with triacetyl cellulose (TAC) as its main component. It has excellent light transmittance, heat resistance, weather resistance, and dimensional stability. Example

[0033] Structural parameters: Copper layer thickness: 0.3μm (purity 99.9%); Alloy layer 240 thickness: 0.1μm (Cu 70%, Ni 29%, Ti 1%); Transparent base film 220: TAC film (thickness 50μm); Bonding method: First OCA optical adhesive 300, second OCA optical adhesive 500 (thickness 25μm).

[0034] Test results: Corrosion resistance: After storage at 85℃ / 85%RH for 240 hours, the metal mesh resistivity change rate is 3.8% (compared to 65% for traditional Cu mesh); Optical performance: Total light transmittance is 91.2%, haze is 1%; Flexibility: No cracks are observed when the bending radius is 1mm (compared to ≥2mm for traditional solutions). Example

[0035] Structural parameters: Copper layer thickness: 0.5μm; Alloy layer 240 thickness: 0.5μm (Cu 85%, Ni 14%, Ti 1%); Transparent base film 220: TAC film (thickness 40μm).

[0036] Test Results: Conductivity: The sheet resistance of the copper + copper-nickel-titanium alloy layer (240) is 0.06 Ω / sq. After being processed into a metal mesh, the equivalent sheet resistance is 3 Ω / sq. After being bonded and assembled with the polarizer (400) and display module (600), and stored in an environment of 85℃ / 85%RH (high temperature and high humidity) for 240 hours, the metal mesh resistance increased by only 0.05 Ω, an increase of only 1.6%. In contrast, the sheet resistance of the traditional copper mesh (copper + blackening layer) is 0.06 Ω / sq. After being processed into a metal mesh, the equivalent sheet resistance is 3 Ω / sq. After being bonded and assembled with the polarizer and display module, and stored in an environment of 85℃ / 85%RH (high temperature and high humidity) for 240 hours, the metal mesh resistance increases to 90 Ω, an increase of 3000%. Thickness control: The total thickness of the touch sensor 200 is 41.5μm (40um TAC + 0.5um copper + 0.5um copper-nickel-titanium alloy + 0.5um copper), which is 9.8% thinner than the traditional solution (46μm = 40um TAC + 0.5um copper + 0.5um copper + 5um barrier layer).

[0037] This solution can be widely used in capacitive touchscreens for mobile phones, tablets, automotive displays, and other fields, and can be applied to LCD, OLED, and electronic paper display fields. It is especially suitable for flexible OLED display modules.

Claims

1. A capacitive touch screen, characterized by Comprising: a display module; a polarizer disposed above the display module; and a touch sensor disposed between the polarizer and the display module, the touch sensor comprising a metal mesh circuit pattern composed of a copper layer and an alloy layer. The thickness of the copper layer is 0-1 μm.

2. The capacitive touch screen of claim 1, wherein, The thickness of the copper layer is 0.3-0.8 μm.

3. The capacitive touch screen of claim 2, wherein, The thickness of the alloy layer is 0.1-1 μm, and the alloy layer is located on the side close to the polarizer.

4. The capacitive touch screen of claim 1, wherein, The touch sensor is a double-sided structure comprising a touch sensor upper electrode and a touch sensor lower electrode, which are separated by a transparent base film.

5. The capacitive touch screen of claim 1, wherein, The transparent base film is a TAC film.

6. The capacitive touch screen of claim 5, wherein, ​

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