How do smartphone screen protection technologies, LCD and tempered glass, work with capacitive touch technology?

LCD and tempered glass are technologies for protecting smartphone screens to prevent scratches and improve durability, respectively. They work in conjunction with capacitive touch panels to make smartphones more durable and enhance the user experience. Currently, companies are continuing research to further develop these technologies.

 

Smartphones have become an indispensable part of modern life. As we use our smartphones on a daily basis, the screen is prone to small scratches, and manufacturers use liquid crystal protective film or tempered glass to protect it. If the screen was made of glass, it would shatter if you dropped it on the floor, but with this protection, the smartphone screen is virtually unbreakable. What are smartphone screens and their films made of?
To understand smartphone screen materials, it’s important to first understand how touch works. Smartphones use capacitive touch panels. They use static electricity to detect the position of your finger, which is a very sophisticated technique. Your smartphone’s screen isn’t just a tool for receiving inputs; it’s a sophisticated sensor system that sensitively detects electrical signals and determines their exact location and strength when you touch the screen. For example, when you touch the screen with your finger, electrons are drawn to that point, and the circuitry behind it detects the slight change in current that occurs and executes your command. For this reason, it can recognize wherever your finger touches, allowing simultaneous input from multiple points, and various technologies are being developed to increase the touch sensitivity of the screen. Thanks to these technologies, we can easily perform precise tasks and various multi-touch gestures with our smartphones. However, the screen does not respond to nails, gloves, or clothing types that do not conduct static electricity.
The structure of a smartphone consists of two plates with a film (top and bottom), the top plate calculates the presence of inputs and their coordinates, and the bottom plate receives the information and sends signals to the controller. Since the signals exchanged are both electricity and light, if the top and bottom plates were made of opaque materials, the light would be blocked by the plates and would not be transmitted to the electrodes. Therefore, a material that is both transparent and electrically conductive is required, and several transparent electrodes have been developed. Among these, indium-tin oxide (ITO) films are the most efficient. The electrode is formed by plasma depositing a thin layer of indium acid on PET, a material widely known as plastic, and the film is transparent, electrically conductive, and stable at room temperature, so it is harmless to the human body. However, ITO film alone is not strong enough to withstand external impacts, so liquid crystal protective film and tempered glass were developed to prevent the screen from cracking or scratching when accidentally dropped or exposed to rain or snow.
A screen protector is a film that is placed over the screen to protect it from microscopic dust and everyday scratches. These films are made of materials that adhere well to the screen with low adhesion, are not reactive, and conduct electricity well, and are usually made of plastics, especially PET or silicone. Silicone, in particular, is used not only in smartphones but also in semiconductors because it is a stable material and can form various compounds with other atoms. However, since it is a type of plastic, it can be easily scratched by knives, nails, etc.
Tempered glass protects your smartphone’s liquid crystal in a similar way to liquid crystal protective film, but it’s much stronger than film. It’s made through a process where regular glass is cooled to include impurities, which are larger than the glass particles, so they take up more space, causing the particles to cluster around them. This means that they have a higher particle density, which makes them much more resistant to scratches. Tempered glass also has the advantage of being much more pleasant to the touch than film. However, the downside is that it’s thicker and heavier than a protective film.
As the technology for protecting smartphone screens improves, so does the experience for smartphone users. Smartphone screens, which detect static electricity from hands and process signals, are made of transparent electrodes with good electrical conductivity. The liquid crystal protective film and tempered glass used for the screen have their own advantages and disadvantages. The film is vulnerable to scratches, and the thickness and weight of tempered glass is a problem. Currently, smartphone companies are conducting various research and development to solve these problems. For example, liquid crystal protective films are being developed to be more scratch-resistant and less prone to fingerprints, while tempered glass is focused on making thinner and lighter products while maintaining its strength. More recently, researchers have been combining glass tempering technologies with nanomaterials to create thinner, more flexible protective layers while maintaining higher strength. These technologies are not only providing a more pleasant experience for users, but are also helping to extend the lifespan of smartphones. With these efforts, we can look forward to the arrival of a scratch-free smartphone society.