Capacitive touch is now the mainstream, but piezoelectric touch may be the future

According to DisplaySearch's forecast analysis, the global output value of touch products was approximately US$4.3 billion in 2009, and will reach US$14 billion in 2016. In other words, the future compound annual growth rate of touch products will exceed 18%. Currently, among all electronic related fields, except for touch, no other industry can have such a high annual compound growth rate in the next few years, which is a very important reason why we believe that touch can be successful.

Two Milestone Events in the Touch Screen Market

In the past decade, two very important things have happened in the field of touch. The first thing is the launch of the iPhone. Multi-touch and the zooming, shrinking and rotating functions under multi-touch were not invented by Apple. However, in recent years, Apple's iPhone and iPad have been very successful after their launch, which shows that this product actually has a meaning in the market.

Qian Jinwei, CEO of Ruiyang Optoelectronics: Now is the best time for touch screen, the touch screen era has arrived.

Analyzing the functions of iPad, we can clearly find that, except for the application of multi-touch on the 9.7-inch screen, the other technologies it adopts are all very mature parts of existing technologies. This means that people are willing to experience the feeling of multi-touch regardless of medium or large size. The success of iPhone and iPad has made an indelible contribution to promoting multi-touch technology and making it more popular and widespread in human life.

The second major event in the touch field is the support of multi-touch in Microsoft Windows. Microsoft's technology solves the multi-touch problem at the operating system level, thus solving the patent problem of multi-touch. This further encourages other system manufacturers to start supporting multi-touch systems on their respective operating system platforms, which is of great significance.

One concept that needs to be clarified is that Windows 7 can support unlimited points. The so-called ten-point touch and four-point touch now are all due to the limited technology of control chip manufacturers. There is no limit to the number of points supported by Windows 7.

Capacitive touch is the mainstream

Since touch is an indirect measurement technology, there are more than 100 types of touch. For example, capacitive touch determines the location of a point through the process of current change; ultrasonic touch determines the location and direction by where the shadow falls during the ultrasonic emission; and optical touch determines the location of a point through image processing. It can be clearly seen that they are all indirect measurement technologies, and any indirect measurement technology can be made into a touch technology through some algorithms. This is one of the main reasons why there are so many touch technologies.

By summarizing and organizing, we can divide touch technology into 11 categories, of which 4 categories can support so-called multi-touch, including capacitive, piezoelectric, etc. Basically, they all support multi-touch, and the number of touch points is unlimited.

There is no perfect touch technology in the world. Each technology is imperfect and has its own shortcomings and limitations in use. For example, the capacitive touch widely used by Apple cannot be used when wearing gloves and is very afraid of water. For example, optical touch works well on large sizes, but not on small sizes. Moreover, the optical touch attenuates very quickly. It is very sensitive at the beginning, but the sensitivity decreases over time.

At present, the main patents of touch technology have expired. It has been more than 20 to 30 years since the invention of capacitive, infrared, and ultrasonic touch technologies. Because of this, more newcomers can be attracted to participate in research, and then new patents can be proposed, making the types of touch technology more and more diverse.

The most popular touch technology on the market is projected capacitive technology, which can measure the change of current through the finger, and detect the position of the point through the change of charge. The biggest advantage of projected capacitive technology is that it can achieve true touch, but its biggest problem is that it can only be used with the fingertips, not nails. Due to Apple, the current mainstream position of this technology in the market is unquestionable.

Piezoelectric multi-touch has a promising future

Among the many touch technologies, RaySun opted for piezoelectric multi-touch technology for four main reasons. First, it is an infinite multi-touch technology that fully supports Windows 7 and Android. Second, this technology has very high precision and very small errors. Third, piezoelectric technology can effectively detect the area. Fourth, this technology has no fundamental limitations and can be used even when wearing gloves.

In fact, this technology combines the technical features of capacitors and resistors and was commercialized before 2005. Capacitive touch is most afraid of TFT and RF interference problems, but piezoelectric does not have this problem. It has very high anti-EMI and ESD capabilities and very light input. In addition to capacitive, piezoelectric multi-touch technology also has the advantages of resistive, which can detect both finger pulp and fingertip.

The difference between piezoelectric touch and projected capacitive is not that big. First of all, their glass structures are exactly the same, both use a matrix structure. The biggest difference is that capacitive touch uses current, while piezoelectric uses voltage to act on coordinate changes to determine the position of a point.

Of course, piezoelectric multi-touch technology also has its own shortcomings. It has many process lines and very high requirements for manufacturing technology. Even if commercialized products are launched, not many can be mass-produced. Among all domestic manufacturers, Ruiyang Optoelectronics is currently the only company that can produce and develop this technology. Not long ago, Ruiyang Optoelectronics' piezoelectric multi-touch solution has passed Microsoft's Windows 7 multi-touch (ten-finger) certification test, becoming the first touch module manufacturer in China to pass this certification.