What does multi-touch mean?

In the future, the touch-screen mobile phone should be a big screen and slim, and users only need to operate it with one hand. IPhone shows people an unprecedented new mobile phone operation experience, with no stylus, no buttons and multi-touch. Almost at the same time, the industry has brought TouchFlo technology, which leads the industry, so that people have a new understanding of WindowsMobile operating system-adapting to the development of touch technology, constantly improving user experience and facilitating mobile phone operation. More interestingly, with the popularity of touch screen technology in the past two years, many so-called "cottage phones" have also incorporated touch function into mobile phones within 1,000 yuan. The evolution of mobile phone screens is rapid. First, the color of mobile phone screen ranges from black and white to color, from 256 colors to millions of colors, and finally to full-screen large-size multi-touch now. Mobile phone manufacturers are constantly updating the hardware features of mobile phone screens. The reason is simple: when people use mobile phones, the only human-computer interaction tool is the screen, which is indispensable for making phone calls, sending text messages, or doing business and entertainment functions. Therefore, to simplify the user's operation process directly, it is natural to think of making the mobile phone screen operable at the same time, not just for display. The evolution of mobile phone screen is very rapid. Let's take Motorola as an example. It used to be a leader in handwriting input. 1999, Motorola launched the world's first Chinese handwritten touch-screen mobile phone A6 188. At that time, the traditional numeric keyboard input method of mobile phone was subverted, and the text input part of mobile phone was left to touch screen and stylus. This alone is enough to attract consumers' attention and become the best choice for countless high-end users at that time. However, it seems that at that time, people simply equated the function of the touch-screen mobile phone with handwriting input, ignoring that the touch function can actually penetrate into various functions of the mobile phone itself, improving the overall operating efficiency and visual experience of the mobile phone. As a result, with the passage of time, touch-screen mobile phones with no handwriting function have appeared in the market. For example, Motorola's E680 and E6 promote touch-screen phones with the theme of games and entertainment respectively, while Microsoft gradually downplays non-touch-screen phones, giving priority to improving the user experience of touch-screen, and strengthening and highlighting the convenience brought by touch-screen. But all this was interrupted by the shocking listing of the iPhone. The IPhone completely subverts the experience of using the touch screen, and makes everyone understand that a mobile phone can complete complex operations that could only be completed through complicated menus by finger touch or multi-touch. The IPhone also emphasizes the seamless integration of software and hardware. At the beginning of OS (operating system) design, the influence of touch on program operation was considered, and at the same time, the details such as UI (man-machine interface), program design, button style and so on were paid special attention, which all embodied the purpose of fundamentally solving the basic experience of human-computer interaction. Its appearance has led to the rapid extension of the whole touch screen technology and the reform of related software industries. Handwriting is not equal to touch screen. What kind of high-tech product is the touch screen? Let's talk about the hardware type of the touch screen first. At present, ordinary touch-screen mobile phones on the market (such as Motorola, Sony Ericsson, Samsung, dopod and other brands) usually use resistive touch screens. This kind of touch screen is controlled by pressure sensing, and its main component is a resistive multilayer composite film screen, which matches the surface of the display screen very well. When a finger or stylus clicks on the touch screen, the two conductive layers contact at the touch point, and at this time, the resistance changes, generating signals of X axis and Y axis, which are then sent to the touch screen controller. The controller detects this contact point and calculates the exact position, and then operates in the way of simulating a mouse, which translates into different specific operating effects. This is the most basic principle of resistive touch screen. Simply put, a touch screen is equivalent to an input sensing device, which can directly input or operate the device instead of a mouse or keyboard. Because the operation of the touch screen is completely WYSIWYG, it is an absolute positioning process. As long as the menu or button of the function that the user wants to realize is touched on the screen, the effect can be presented immediately, and it is not necessary to change through the operation of hardware buttons (navigation keys, function keys, etc.). ) on the mobile phone, this not only saves the manufacturing and design cost of the hardware buttons of the mobile phone, but also saves valuable design space for the screen of the mobile phone. At present, resistive touch screen technology is very mature, and the production cost is reduced after mass production. It has been used as the basic configuration of mobile phones by most mobile phone manufacturers and even "cottage" manufacturers, and has been widely used in their new products. However, the technology of resistive touch screen is limited to single touch in function, and because there is no hard material to protect the front of resistive touch screen, it is easy to cause screen damage in users' daily use. Therefore, if the touch screen wants to make a new breakthrough, it still needs innovation. As a result, new technologies came into being. Capacitive touch screen solves the biggest problem of resistive touch screen-the use of high hardness touch screen, which makes capacitive touch screen have a gorgeous appearance and a hard shell, which greatly promotes the development of touch screen technology. At the same time, due to its unique design principle, the unique function of multi-touch has never been possible. From the structure of this kind of touch screen, it is mainly to plate a transparent film layer on the glass screen, then add a protective glass layer outside the conductor layer, and then lay long electrodes on the four sides of the touch screen to form a low-voltage AC electric field in the conductor. After touching the screen by hand, the current from four electrodes will accurately measure the position of the touch point in a way of crossing ten times. This design also ensures the durability of the product itself. Generally speaking, the capacitive touch screen can have enough space to add a protective glass, which can completely avoid the water ripple phenomenon that is easy to appear in the use of the resistive touch screen and better ensure the screen display effect of the touch screen. Based on the touch principle of capacitive touch screen, multi-touch operation has become the latest technical highlight. In principle, resistive touch screens can only accept one touch point at a time. If the number of touch points increases, the system will not be able to correctly judge the position of the touch point, so it will not be able to respond correctly. However, the principle of capacitive touch is different. The display screen can accept the analysis and judgment of two or more contact points, so as to complete more complex program operations, such as enlarging or reducing pictures with two fingers at the same time, browsing web pages, zooming in at any time, and so on. It's no longer difficult to surf the Internet using mobile phones. Multi-touch is the development direction. The success of iPhone benefits from the perfect combination of software and hardware, and also benefits from the OS architecture tailored for touch technology. Based on this design, users can input characters without using a hardware keyboard at all, which reduces the wear of hardware keys, and manufacturers also save design space, leaving room for large-size display screens and improving the display effect. Good touch screen programming can make users abandon the stylus completely, which can not only save the stylus accessory, but also solve the headache problem that it can not be operated with one hand in some special occasions. The author boldly believes that the future touch-screen mobile phone should be developed in the direction that the hardware is large screen, the figure is slim and the user only needs to operate with one hand. The latest report released by IMSResearch, a market research company, predicts that although the global sales of touch-screen mobile phones were less than 30 million last year, the sales of touch-screen mobile phones will exceed 230 million by 20 12. Because the emergence of iPhone has brought an unprecedented sense of crisis to all mobile phone manufacturers, this is the driving force for more touch-screen mobile phones to go public. Nokia has announced that it will focus on the development of touch-screen mobile phones, which will be fully rolled out in the future product line. Microsoft will implement multi-touch in WindowsMobile7 next year, completely keeping up with the development trend of touch screen. In order to make up for the inherent shortcomings of their respective operating systems, manufacturers try their best to optimize the touch function and one-handed operation performance. For example, the mobile phone uses TouchFlo technology to optimize the system, completely getting rid of the original scroll bar scrolling items. As long as you hold down the screen and slide up and down, you can locate and select items freely, and you can simulate inertial sliding, and then stop slowly, completely simulating the current operating experience on the computer. These innovative experiences, called touch screen gesture recognition, are also widely used in browsing pictures and web pages. I believe that in the future, due to the continuous development of touch screen technology, the corresponding software operation will be more user-friendly and bring users a better operating experience. Related links introduce the technical principles of various touch screens. The resistive touch screen can only judge one touch point at a time when it works. If there are more than two touch points, it is impossible to make a correct judgment, so the resistive touch screen is only suitable for judging simple actions such as clicking and dragging. Multi-touch of capacitive touch screen can decompose the user's touch into two tasks: collecting multi-point signals and judging the meaning of signals, and complete the judgment of complex actions. The surface touched by the fingers of resistive touch screen is a hard coating to protect the PET (Polyester Film) layer below. There are two transparent conductive layers ITO (Indium Oxide, weak conductor) between the surface protection hard coating and the glass bottom layer, which correspond to the X axis and the Y axis respectively, and they are insulated by tiny transparent insulating particles. The pressure generated by touch will connect the two conductive layers. When different points are pressed, the resistance value from this point to the output terminal is different, so the output will be different from this point. This is the most basic principle of resistive touch screen. Capacitive single-point touch screen Single-point capacitive touch screen only uses one layer of ITO. When the finger touches the surface of the touch screen, a certain amount of charge will be transferred to the human body. In order to recover these charges, charges are added from four corners of the screen, and the amount of charges added in all directions is proportional to the distance of the touch point, from which we can calculate the position of the touch point. Capacitive touch screen can only judge one touch point at a time. If you touch more than two points at the same time, it will not be able to respond correctly, or it will react confusedly. The task of multi-touch of multi-touch capacitive touch screen can be divided into two aspects: one is to collect multi-touch signals at the same time, and the other is to judge the meaning of each signal, that is, gesture recognition. Compared with touch technology, which can only accept a single input, multi-touch technology allows users to touch the display screen in multiple places at the same time, so that they can expand and rotate web pages or pictures. Apple iPhone only allows two fingers to operate, so it can be called "two-touch", and Microsoft's upcoming Surface computer can respond to 52 touch points at the same time. In order to realize multi-touch function, multi-touch screen and single-touch screen adopt completely different structures. From the outside of the screen, a single touch screen has only a few signal lines (generally 4Pin or 5Pin), while a multi-touch screen has many leads. From the inside, the conductive layer of single-point touch screen is just a flat plate, while multi-point touch screen is divided into many relatively independent touch units on the flat plate, and each touch unit is connected with external circuits through independent wires, and all touch units are arranged in a matrix on the plate. In this way, when the user's finger touches a certain part on the screen, a signal will be output from the corresponding detection line. When the finger moves to another part, it will output a signal from another detection line. Apple applied for two patents of multi-touch panel for iPhone-self-capacitance and mutual capacitance. From the use point of view, there is no essential difference between self-capacitive touch screen and mutual-capacitive touch screen, the difference lies in their internal structure-mutual-capacitive touch screen has isolated driving lines and detection lines, while self-capacitive touch screen has only one layer of transparent electrodes. There are 19 rows on the horizontal and vertical chessboard of Go, and at most 19× 19=36 1 piece can be put. Similarly, the criss-crossing detection lines on the multi-touch screen also have many intersections, and each intersection can be regarded as a touch point. From the perspective of touch screen, it can really support many touch points. How many touch points can actually be supported is ultimately determined by DSP chips and software. Development trend of capacitive multi-touch screen Capacitive multi-touch screen has been applied to handheld devices such as iPhone. Positioning single point trajectory/simulating double-click of mouse is its basic function, and the recognition and application of multi-finger gesture operation has become a hot spot in the current market. In portable applications, users can only operate devices with one hand, so it is particularly important to recognize gestures such as multi-finger grasping/translation, stretching/compression, rotation and page turning. In the past, due to factors such as cost and technology, the use of resistive control panels far exceeded that of capacitive touch technology. But recently, with the progress of technology and mass production, the price of capacitive touch screen is declining, and the price gap with resistive touch screen is getting smaller and smaller, and it gradually has the ability to compete with resistive touch screen in price. With the maturity of the market and the reduction of cost, multi-touch technology will gradually replace the traditional single-touch technology with its unique selling point, comprehensive function and stability.