Optical touch is expected to replace projected capacitance

In recent years, as touch panels have become thinner and thinner, the popularity of wearable devices such as smart watches has risen, and the demand for wearable touch screen displays has continuously increased. However, when the touch panel is applied to a large-size, reproducible application, the transparent conductive film ITO, which has an exclusive position among the capacitive touch panels, faces many challenges that are almost impossible to solve.

In order to solve the difficulties brought about by ITO, many manufacturers are anxious to find other alternatives to ITO such as metal meshes, carbon nanotubes, and silver nanowires. In addition, there is also a group of people who choose to go to optical touch control, such as the era of photoelectricity, because ITO on the large size of the panel due to low yield caused high cost, but also because of its material properties and can not be applied to the soft panel Optical touch technology has shown many advantages in these areas. Lin Zhixiong, general manager of Times Optoelectronics, pointed out that optical touch can solve the capacitive pain, and therefore, even Intel is optimistic about this technology, invested 20 million euros in optical touch developer Swedish supplier FlatFrog.

Times Optoelectronics focuses on the development of optical technology. Although it has not yet been mass-produced, it seems to have great potential. Its technology is similar to that of FlatFrog. It also uses infrared light emitted to hit the glass and receives light through the receiver. Sensing touch points is only a simple process, reducing costs. Lin Zhixiong said that his technology is to provide soft cables, including receivers and LEDs, which can be touched just by sticking around the panel. The biggest advantage compared to ITO is that there is no yield problem. “It can be removed and reattached at any time,” he said. There is no production difficulty, no clean room is needed, and material acquisition is easy. It is easy to import and supply. Chain, and now can be done within the 2-200-inch range of panels.

Unlike ITO, which is wired on the panel, optically senses the position of the touch through light, and the light has a high divergence rate. Not only is the density higher than that of ITO, but it can also be used in flexible panels; and due to the lack of ITO In addition to having a higher transmittance, the layer film also has a problem that the yield is not high when the ITO is attached to the cover glass. In addition, since the refractive index of the light is calculated, it can be used even in water, and this is also a capacitance that cannot be achieved by touch. Lin Zhixiong pointed out that the only drawback is that the optical touch is more power-consuming, but because the light transmittance is high and the power of the LCM is saved, the two are offset, and although they are still more power-consuming than the capacitive touch, they are also Acceptable range.

However, although optical touch seems to be more competitive than capacitive, manufacturers still mostly hold a wait-and-see attitude. Lin Zhixiong said that since capacitive touch has developed for 20 years, it will overturn in the short term. The supply chain was changed to optically difficult. However, if one can persuade the market to adopt, then the two technologies will face each other.