Touch screen laminating process and touch screen

Abstract

The application relates to a touch screen laminating process and a touch screen, and relates to the technical field of touch screen lamination. The application provides a sheet optical adhesive, which is used to avoid the formation of jagged edges by the overflowed liquid adhesive at the laminating edge; the TP and the LCM are subjected to function inspection and appearance cleaning; the sheet optical adhesive is pasted on the surface of the TP, the TP and the LCM are laminated, and a touch screen finished product is obtained. The use of the sheet optical adhesive cannot cause the liquid adhesive to leak out, so that the laminating edge and the surface of the touch screen can be kept clean and tidy, and the flatness of the sheet optical adhesive is high, the uniformity of the laminating material between the TP and the LCM can be ensured, and the phenomena of polarized light and light leakage of the touch screen can be avoided.

Description

Technical Field

[0001] This application relates to the technical field of touch screen bonding, and in particular to a touch screen bonding process and a touch screen. Background Technology

[0002] With the development of touch screen technology, as a simple, convenient, and natural human-computer interaction device, touch screens have been widely used in mobile phones, in-vehicle navigation systems, industrial control, medical care, self-service terminals and other fields, simplifying human-computer interaction and improving the user experience.

[0003] Currently, most touch screens use full lamination technology, which means that the TP (Touch Panel) and LCM (LCD Module) are bonded together using optical adhesive. Compared with traditional lamination methods, this bonding method has a thinner structure and better light transmittance.

[0004] Invention patent publication number CN113391725A discloses a touch screen bonding process and structure, including: S1, designing a printing pattern according to product characteristics; S2, printing LOCA bonding material onto the upper surface of the display unit according to the printing pattern design to form a first LOCA bonding layer; S3, pressing the touch sensing unit onto the first LOCA bonding layer; S4, curing the first LOCA bonding layer; S5, printing LOCA bonding material onto the upper surface of the touch sensing unit according to the printing pattern design to form a second LOCA bonding layer; S6, pressing a protective cover onto the second LOCA bonding layer; S7, curing the second LOCA bonding layer. Printing LOCA bonding material by printing can easily cause bonding material to adhere to non-bonded areas during bonding, leading to jagged edges.

[0005] Chinese Patent Publication No. CN115457883A discloses a bonding process between an automotive touchscreen and an open cell, comprising the following steps: image acquisition, bonding of the automotive touchscreen and an LCD panel, and water-based adhesive curing. By using feature point extraction to calculate the corner and midpoints of the automotive touchscreen and the LCD panel, the accuracy of bonding between them is improved, thereby addressing issues of high reflectivity and poor visual effects. Furthermore, when using water-based adhesive to bond the automotive touchscreen and the LCD panel, a pad is used to support both, improving the flatness of the bonding surface and preventing the formation of bonding bubbles, thus increasing production efficiency and yield. It also improves the bonding optical effect between the automotive touchscreen and the LCD panel. Water-based adhesive bonding is prone to overflow, resulting in jagged edges at the bonding edges. Summary of the Invention

[0006] To address the issue of jagged edges appearing at the bonding edges during the touchscreen bonding process, this application provides a touchscreen bonding process and a touchscreen.

[0007] Firstly, the touch screen bonding process provided in this application adopts the following technical solution: A touch screen bonding process includes: providing sheet optical adhesive to prevent overflowing liquid adhesive from forming jagged edges at the bonding edges; performing functional testing and appearance cleaning on the TP and LCM; attaching the sheet optical adhesive to the surface of the TP, bonding the TP and LCM, and obtaining the finished touch screen.

[0008] By adopting the above technical solution, a small amount of liquid adhesive will leak out between the two bonding surfaces during the bonding process. Since the area of ​​the TP (touch panel) is often larger than that of the LCM (liquid membrane), the leaked liquid adhesive will remain on the larger TP surface. During bonding, the touchscreen needs to touch objects such as the bonding device, and the leaked liquid adhesive will adhere to these objects. When separating the objects from the touchscreen, the liquid adhesive, under tearing force, will create jagged edges on the bonding surfaces. These jagged edges will, on the one hand,... Liquid adhesive affects not only the neatness of the touchscreen's appearance but also its sensitivity and touch performance. Therefore, sheet optical adhesive is used instead of liquid adhesive. Sheet optical adhesive prevents adhesive leakage, keeping the bonding edges and the touchscreen surface clean and tidy. Furthermore, the high flatness of sheet optical adhesive ensures uniform bonding between the TP and LCM, preventing phenomena such as light polarization and light leakage. Using sheet optical adhesive for bonding helps ensure the touchscreen's clean appearance and stable performance.

[0009] Optionally, a heated glass is bonded between the TP and the LCM. The heated glass is used to maintain the TP at its optimal operating temperature and to prevent the touchscreen from fogging in cold environments and to ensure the normal operation of the TP. The bonding process specifically includes: bonding sheet optical adhesive to the surface of the TP and the surface of the heated glass, bonding the TP, the heated glass and the LCM to obtain a bonded product.

[0010] By adopting the above technical solution, the heated glass is a resistance heating device that can generate heat on the glass surface through the thermal effect of current by applying a small voltage to both ends of the glass. Due to its transparency, the heated glass can be used in touch screens without affecting the display performance of the LCM. Because of its heating function, the TP can maintain stable performance in cold environments and prevent surface frost from forming on the touch screen in high humidity environments, allowing the touch screen to maintain normal use in various environments. Since the TP is on the outermost side and the LCM is on the innermost side in the touch screen setup, the TP often has the largest area and the LCM has the smallest area. Therefore, the bonding gap can be exposed on the inner side. Therefore, by applying sheet optical adhesive to the surfaces of the TP and the heated glass, it can be ensured that the TP, heated glass and LCM are completely covered by the sheet optical adhesive during the bonding process.

[0011] Optionally, a buffer film is also adhered between the heated glass and the LCM, the buffer film being used to reduce the impact of the heat emitted by the heated glass on the LCM.

[0012] By adopting the above technical solution, the heating function of the heated glass is mainly to ensure the normal operation of the TP and to prevent fogging on the surface of the touch screen. The components that perform this function are all located outside the heated glass. However, for the LCM located at the bottom of the touch screen and inside the heated glass, the heat generated by the heated glass may cause the LCM to operate at an excessively high temperature, resulting in a decrease in operating performance. By providing a buffer film, the heat generated by the heated glass is isolated when it is dissipated to the LCM, which helps to ensure that the LCM is at a normal operating temperature, thereby facilitating the normal operation of the touch screen.

[0013] Optionally, the bonding of the TP, the heating glass, and the buffer film specifically includes: attaching sheet optical adhesive to the surface of the TP, performing a degassing pretreatment, vacuum bonding it with the heating glass, and obtaining a first bonded product after degassing treatment, aging treatment, and appearance inspection; attaching sheet optical adhesive to the heating glass side of the first bonded product, vacuum bonding it with the buffer film, and obtaining a second bonded product after degassing treatment and appearance inspection.

[0014] By adopting the above technical solution, since the buffer film is a flexible film, repeated bonding can easily damage the buffer film. Therefore, the TP and the heating glass are bonded first to minimize the pressure on the buffer film. In addition, due to the flexible nature of the buffer film, it is difficult to support the sheet optical adhesive, which can easily cause positional slippage during the bonding process. By bonding the sheet optical adhesive to one side of the heating glass, it is beneficial to ensure accurate bonding.

[0015] Optionally, the area of ​​the buffer film is smaller than the area of ​​the heated glass, and the area of ​​the LCM is larger than the area of ​​the buffer film. The second vacuum bonding specifically includes: the frosted film is pasted to the middle of the sheet optical adhesive, and adhesive paper is pasted on the outer side of the buffer film. The adhesive paper can cover the sheet optical adhesive and can be peeled off after bonding.

[0016] By adopting the above technical solution, the area of ​​the buffer film is smaller than that of the heated glass, ensuring that the heated glass can completely cover the buffer film after bonding, avoiding additional trimming. Furthermore, the buffer film is placed in the middle of the heated glass, leaving a portion of the sheet optical adhesive on the outer side of the buffer film, which can be used to enhance the adhesion with the LCM. Since the sheet optical adhesive is exposed on the outer side, it is covered with adhesive tape to avoid damaging the adhesive layer during bonding. The adhesive tape can be easily peeled off after bonding, ensuring the normal progress of the bonding process.

[0017] Optionally, the process of bonding the second bonding product and the LCM to obtain the finished touch screen specifically includes: removing the adhesive tape, applying water-based adhesive to the surface of the buffer film, applying the water-based adhesive to the middle of the matte film, vacuum bonding the second bonding product and the LCM, bonding the outer sheet optical adhesive of the matte film to the edge of the LCM to prevent the water-based adhesive from flowing out, and obtaining the finished touch screen after debubbling treatment, aging treatment and appearance inspection.

[0018] By adopting the above technical solution, since the LCM is composed of many modules bonded together, the edges of the LCM often have a stepped arrangement, which makes it difficult to bond the stepped arrangement during the bonding process. Using water-based adhesive can adapt to and fill the stepped arrangement of the LCM edges, thus enabling the LCM to be bonded smoothly. However, the use of water-based adhesive is prone to overflow, forming serrated burrs on the sides of the touch screen, which is not conducive to the cleanliness of the touch screen surface. Therefore, exposed sheet optical adhesive is left around the buffer film. During the bonding process, the water-based adhesive will encounter greater resistance when spreading the sheet optical adhesive, and can only spread in the direction that has not come into contact with the sheet optical adhesive. This allows the water-based adhesive to be distributed more evenly between the buffer film and the LCM. While avoiding water-based adhesive overflow, the water-based adhesive can fill the stepped arrangement of the LCM edges, which is beneficial to the smoothness of the LCM bonding.

[0019] Optionally, the buffer film is a matte film.

[0020] By adopting the above technical solution, the surface of the matte film on the outer side of the touch screen is slightly rough, so that the light shining on the touch screen from the outside is diffused and scattered, reducing the reflectivity of the touch screen. Even in a bright light environment, the touch screen can remain clear with a lower brightness, so that the touch screen is not too dazzling and helps to avoid visual fatigue or damage to the user.

[0021] Secondly, the touch screen provided in this application adopts the following technical solution: A touch screen is prepared using the above-described touch screen bonding process.

[0022] By adopting the above technical solution and the touch screen prepared by the above touch screen bonding process, the touch screen has good surface cleanliness and better display performance. Moreover, under the action of heated glass, the touch screen can operate normally in cold or humid environments, and has good applicability. By adding a frosted film between the heated glass and LCM, the touch screen can reduce reflection in strong light scenes. Furthermore, by allowing the edge of the sheet optical adhesive to flow down around the frosted film, the water-based adhesive used to bond the LCM and the frosted film, which have uneven surfaces, will not overflow into the bonding gap, ensuring the clean appearance of the touch screen.

[0023] In summary, this application includes at least one of the following beneficial technical effects: 1. Using sheet optical adhesive prevents liquid adhesive from overflowing during the touch screen bonding process, thus avoiding the jagged burrs formed by overflowing liquid adhesive. This helps ensure a clean appearance of the touch screen after bonding and avoids the impact of such burrs on the touch screen's touch performance. 2. The use of heated glass enables the touchscreen to maintain its touch performance in cold environments and avoids the inconvenience caused by fogging on the touchscreen surface. In addition, the use of a buffer film ensures that the heat generated by the heated glass does not have an excessive impact on the working state of the LCM, thus ensuring the normal operation of the touchscreen. 3. In addition to utilizing the heat insulation properties of the buffer film, the buffer film also creates a space between the LCM and the sheet optical adhesive where the water-based adhesive can flow. This allows the water-based adhesive to adapt to the stepped arrangement structure that fills the edge of the LCM. Furthermore, because part of the sheet optical adhesive is left at the edge of the buffer film, the water-based adhesive experiences greater flow resistance when it comes into contact with the sheet optical adhesive. This allows the water-based adhesive to fully fill the gap between the buffer film and the LCM, ensuring a smooth and even fit of the LCM. Detailed Implementation

[0024] This application will be further described in detail with reference to the embodiments.

[0025] This application discloses a touch screen bonding process, including: S1 provides sheet optical adhesive.

[0026] The sheet optical adhesive has good light transmittance and adhesion properties, and will not affect the display function of the touch screen. In addition, it also has anti-blue light and anti-glare optical properties. Since the size of the sheet optical adhesive used in each bonding step is different, the size of the sheet optical adhesive needs to be cut according to the specific bonding object.

[0027] In the bonding process of sheet optical adhesive, adhesive tape is required. Since the objects being bonded are usually of varying sizes, adhesive tape needs to be applied to the edges of the larger bonding surfaces to prevent foreign objects from adhering to the sheet optical adhesive during bonding. This would prevent the need for external force to separate the foreign objects during bonding. Therefore, using sheet optical adhesive allows the adhesive tape to cover the exposed surface of the sheet optical adhesive, preventing the sheet optical adhesive from sticking to foreign objects during bonding, thus ensuring a smooth bonding process. Furthermore, after bonding, the adhesive tape can be easily separated from the sheet optical adhesive, facilitating further processing.

[0028] S2. Use sheet optical adhesive to bond TP and heated glass to obtain the first bonded product.

[0029] The size of the sheet optical adhesive used is the same as that of the touchscreen panel (TP). Since the TP is the outermost component of the touchscreen, its area is the largest. This ensures that the bonding gaps of other components bonded to the back of the TP face towards the back of the TP, preventing the bonding gaps from facing outwards and making the touchscreen surface less clean. It also prevents dust and other debris from accumulating in the bonding gaps, which would degrade the touchscreen's touch performance. The sheet optical adhesive is cut to a size close to that of the TP. Because the area of ​​the heating glass is smaller than that of the TP, the area of ​​the sheet optical adhesive needs to be larger than the heating glass, slightly smaller than the TP, but not larger. The heating glass generates heat by applying voltage across its resistors, thus preventing low ambient temperatures from affecting the touchscreen performance of the TP and ensuring its normal operation. In addition, it prevents the touchscreen from getting too cold, which would cause moisture to condense on the touchscreen surface and form a foggy surface. By adding heating glass, the touchscreen can maintain normal operation in different environments, improving its applicability.

[0030] After the sheet optical adhesive is first bonded to the TP, it undergoes a defoaming treatment at a vacuum level of 0.11 MPa for 5 minutes. Due to the large area of ​​the TP, defoaming is necessary before bonding the sheet optical adhesive to prevent gaps between the TP and the sheet optical adhesive, which could cause the sheet optical adhesive to twist and be damaged during bonding, resulting in a scrapped product. After defoaming, the sheet optical adhesive and heated glass are placed in a vacuum laminator for vacuum bonding at a vacuum level of 0.55 MPa for 60 seconds. After bonding, the vacuum is maintained and then reduced to 0.15 MPa for defoaming, which is maintained for 15 minutes. This process removes air bubbles between the sheet optical adhesive and the heated glass. After defoaming, the first bonded product is removed from the vacuum laminator and subjected to aging treatment at 70°C for 120 minutes to ensure complete adhesion between the sheet optical adhesive, TP, and heated glass, guaranteeing stable touchscreen quality.

[0031] S3. Use sheet optical adhesive to bond the first bonded product and the buffer film to obtain the second bonded product.

[0032] The buffer film is used in the preparation of heat insulation materials to play a heat insulation role, so that the heat generated by the heated glass can be released outward without affecting the inner LCM, thereby protecting the LCM from excessively high operating temperature and ensuring the normal operation of the LCM.

[0033] The buffer film can use a matte film with a haze of 25%-30%. The haze of the matte film should not be too high so that the light emitted from the LCM is not excessively fogged by the matte film, ensuring the clarity of the touch screen display. Furthermore, under the effect of the matte film, the touch screen can scatter external light in strong light environments, reducing the reflection of the touch screen and making the display image of the touch screen itself clearer. This avoids the need to increase the brightness of the touch screen to distinguish the display image in high-brightness environments, which is beneficial to the user's visual health and prevents damage to vision caused by excessive light.

[0034] A matte film is applied to one side of the heated glass of the first laminated product. The area of ​​the matte film is smaller than that of the heated glass, and the matte film is applied to the center of the heated glass. Before vacuum lamination, adhesive tape is first applied to the back of the matte film's lamination surface. Due to the thinness of the matte film and the relatively large area of ​​the sheet optical adhesive on the outer side of the matte film, the adhesive tape can be directly applied to the outer side of the matte film, completely covering the sheet optical adhesive on the heated glass. This makes the application of adhesive tape more convenient, simple, and quick, without the need to cut the adhesive tape according to the shape of the matte film and the sheet optical adhesive. After applying the adhesive tape, the matte film and the first laminated product can be bonded together. After the materials are bonded, the adhesive sheet on the outside of the atomized film is kept in place to maintain its bonding performance, so that the adhesive sheet can continue to be used after bonding. The vacuum degree of vacuum bonding is 0.25MPa and the bonding time is 60s. After bonding, the vacuum state is maintained and the vacuum degree is reduced to 0.15MPa for degassing treatment. The degassing process is maintained for 30s to complete the degassing process. Since the thickness of the atomized film is relatively thin, it is not necessary to have too high a vacuum degree and bonding time for bonding. In addition, due to degassing, the air bubbles between the adhesive sheet and the atomized film are removed. After degassing is completed, the first bonded product is taken out from the vacuum bonder to obtain the second bonded product.

[0035] S4. Use water-based adhesive to bond the second bonding product and LCM to obtain a light diffusion film.

[0036] Before lamination, peel off the adhesive tape on the second lamination product to expose the matte film and the sheet optical adhesive. Apply water-based adhesive to the matte film of the second lamination product, focusing on the center. After application, flip the second lamination product over, causing the water-based adhesive in the center to droplet downwards and gather in the center due to surface tension. As the LCM and the second lamination product approach each other, the water-based adhesive begins to contact the center of the LCM, allowing it to diffuse outwards from the center between the matte film and the LCM. This process eliminates air between the LCM and the matte film, with the LCM positioned below. During the diffusion of the water-based adhesive, gravity allows it to spread along the lower part of the LCM. The adhesive spreads to the stepped edges of the LCM, ensuring that the water-based adhesive fully fills the stepped edges that contact the LCM. This prevents air bubbles from forming between the LCM and the second bonded product, and ensures uniform adhesion between the LCM and the second bonded product, avoiding gaps caused by the stepped edges of the LCM. Furthermore, because the outer side of the matte film has exposed sheet optical adhesive, the water-based adhesive encounters significant resistance when it spreads and contacts the sheet optical adhesive, causing it to spread to other areas that have not yet come into contact with the sheet optical adhesive. This ensures that the water-based adhesive is evenly distributed between the LCM and the matte film. While using liquid water-based adhesive to bond uneven edges, the sheet optical adhesive prevents water-based adhesive from overflowing, ensuring a clean surface for the light diffusion film.

[0037] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be covered within the scope of protection of this application.

Claims

1. A touchscreen bonding process, characterized in that, include: Provide sheet optical adhesive to prevent spilled liquid adhesive from forming jagged edges at the bonding edges; Perform functional testing and surface cleaning on TP and LCM; Optical adhesive sheet is pasted onto the TP surface. After degassing pretreatment, it is vacuum-bonded with heated glass. After degassing treatment, aging treatment and appearance inspection, the first bonded product is obtained. A sheet of optical adhesive is adhered to the heated glass side of the first laminated product and vacuum-laminated with a buffer film. After degassing and visual inspection, a second laminated product is obtained. The buffer film is adhered to the center of the sheet of optical adhesive, with the area of ​​the buffer film smaller than the area of ​​the heated glass and the area of ​​the LCM larger than the area of ​​the buffer film, leaving the sheet of optical adhesive protruding from the outer side of the buffer film. A water-based adhesive is applied to the surface of the buffer film, with the adhesive applied to the center. The second laminated product and the LCM are then vacuum-laminated, with the edges of the sheet of optical adhesive and the LCM on the outer side of the buffer film adhered to prevent the adhesive from flowing out. After degassing, aging, and visual inspection, the finished touchscreen is obtained.

2. The touchscreen bonding process according to claim 1, characterized in that, The heated glass is used to maintain the TP at its optimal operating temperature and to prevent the touchscreen from fogging up in cold environments, as well as to ensure the normal operation of the TP.

3. The touchscreen bonding process according to claim 1, characterized in that, The buffer membrane is used to mitigate the impact of heat emitted from the heated glass on the LCM.

4. The touchscreen bonding process according to claim 1, characterized in that, After the buffer film is pasted onto the middle of the sheet optical adhesive, adhesive tape is pasted on the outer side of the buffer film, covering the sheet optical adhesive. The adhesive tape is removed before applying the water-based adhesive.

5. The touchscreen bonding process according to claim 1, characterized in that, The buffer film is a matte film.

6. A touch screen, characterized in that, Prepared using the touch screen bonding process as described in any one of claims 1-5.