Microsoft has a pre-touch technology for mobile devices. This technology uses sensors around the phone's screen to predict the owner's next move and respond accordingly.

In fact, the core of the pre-touch technology is the floating touch technology. In addition to Microsoft, many manufacturers such as Sony, Samsung, and Amazon are also deeply cultivating this technology. Since the birth of the touch screen, people have not stopped improving its technology. The floating touch technology was once considered a gimmick. In fact, its function and significance are far more than that.

What is Hover Touch

Suspension touch is a new technology that is attracting more and more attention from users today. It has been applied to smartphones and a very small number of other digital products, and is still developing. Nowadays, what users pay the most attention to is the floating touch technology of mobile phone touch screen, which is a brand-new technical mode of touch screen mobile phone. The floating touch technology can not only touch the screen with fingers, but also sense the operation of non-conductive fabrics. That is to say, after wearing gloves in winter, you can still use the phone freely, or our fingers do not need to touch at all. The mobile phone can be operated when the screen of the mobile phone is displayed.

For example, the Floating Touch technology allows users to operate the mobile phone without touching the screen when using the mobile phone. The distance between the finger and the screen is about 15mm, and the mouse-like operation can be obtained on the mobile phone.

How Floating Touch Technology Works

Like many smartphones, capacitive touch sensing is used to record user input on the screen. Events that occur when the phone screen is touched are called touch events. Capacitive touch works through a grid of XY electrodes overlaid on the phone, applying the voltage on it. When a finger approaches the electrodes, the capacitance changes and can be measured. By comparing the measurements from all electrodes, it is possible to pinpoint the exact location of the finger.

There are two types of capacitive sensors on a touch screen, mutual capacitance and self capacitance. Mutual capacitance for multi-touch detection. Self-capacitance can generate a stronger signal than mutual capacitance and detect further finger sensing, but multi-point detection is not possible due to an effect known as "ghosting".

The circle represents the touch point, and the red X represents the ghost position

Mutual capacitance for multi-touch

With mutual capacitance, every line intersection in the diagram above forms a parallel plate capacitor. This means that each intersection is a capacitor, which in turn ensures that the measurement can be accurate to each finger, enabling multi-touch. However, because the area of ​​the intersection between the two wires is small, the electric field of the sensor is also small. The sensor is so small that the signal strength is so low that it cannot sense those very weak signals. Therefore, when the user's finger hovers on the screen, the mutual capacitance sensor cannot sense the signal.

Self-capacitance and ghost effects

In the self-capacitance case, each X or Y line in the figure above is a capacitive sensor. Obviously, self-capacitance sensors are larger than mutual-capacitance sensors. The large sensor creates a strong signal that allows the device to detect a finger 20mm above the screen. When a finger rests on or above the screen, the sensor line closest to the finger is activated (X1, Y0). If two fingers are detected, four wires are activated and the ghosting effect occurs. As shown in the figure above, when two fingers are detected, there are four possible touch points (X1, Y0), (X1, Y2), (X3, Y0) and (X3, Y2), and the correct The combination is ambiguous, and thus multi-touch cannot be achieved.

Combining self-capacitance and mutual capacitance to realize floating touch

Floating touch is achieved by running both self-capacitance and mutual capacitance on a capacitive touch screen. Mutual capacitance is used for normal touch sensing, including multi-touch. Whereas self-capacitance is used to detect a hovering finger. Since the floating touch technology relies on self-capacitance, it is impossible to achieve floating multi-touch. That is to say, when performing a hovering operation, the screen does not support multi-touch. The screen can only achieve multi-touch in the case of contact touch.

By using the existing capacitive touch sensor and lowering the threshold of touch entry, it is possible to distinguish between floating touch and contact touch. All Android applications are fully functional. It's just that, as before, only apps that explicitly "listen" to hover touch events will react. That is to say, the realization of the floating touch technology requires the support of the internal program of the application.

The significance of floating touch technology in practical applications

The floating touch technology is a brand-new technical mode applied to touch-screen mobile devices. You can roughly know the effect before you touch it, similar to what button or word we move the mouse to. If it is operable, it will be prompted by color changes.

The floating touch technology can not only touch the screen with fingers, but also sense non-conductive cloth fabrics. In other words, after wearing gloves in winter, you can still freely control the touch screen device. Plus, with this technology, users can operate their phone as usual with water or oil on their hands without worrying about soiling the screen.

Suspension touch technology is favored by major mobile phone giants. In recent years, companies have continued to develop suspension touch technology. The "pre-touch" technology released by Microsoft this time is actually well-prepared. In the past few years, Microsoft has been developing 3D touch technology. This technology can detect the user's finger hovering over the screen, and then make the operating system and programs react to it.

At the beginning, Microsoft wanted to apply 3D touch technology to mobile phones and tablets, but later this technology did not follow, and today's pre-touch technology is likely to be developed on the basis of 3D touch technology. The official Weibo of Microsoft Research released a video introducing the pre-touch technology, showing the principle of how the technology predicts user actions through sensors around the screen. In three dimensions, sensors can analyze the user's grip and finger movements to provide easy-to-use locations and display relevant content.

For example, when holding the phone with one hand, the pre-touch technology brings up a dial that is convenient for the thumb to touch. In addition, the sensor can also lock the direction when the user is watching a video or an e-book, preventing the phone from changing when the user changes posture.

Microsoft believes that pre-touch technology will give touch screens more expressiveness and entertainment. "It uses the human hand as a window to the mind," said Ken Hinckley, principal program researcher at Microsoft. For mobile interactions, I think it has huge potential.

In fact, Sony was the first to act on this anti-sky technology. In 2012, Sony launched the Xperia Sola MT27i. This is a mobile phone with floating touch technology, which can be operated without touching the screen while maintaining a distance of 15mm from the screen. This Sony product is the world's first smartphone equipped with floating touch technology.

In addition, Samsung's 2013 Galaxy S4 also embeds Floating Touch (floating touch gestures); Amazon's Kindle smartphones will use 3D gesture control this year; Apple may also expand 3D Touch in future products. , to realize the floating touch mode.

Headphone maker OM ONE has introduced a Bluetooth speaker that can stay suspended in mid-air. The principle is that there is magnetism in both the chassis and the spherical horn. After the chassis is powered on, it can be suspended in mid-air through the principle of repulsion between the same poles. The sound produced in this state is less likely to be absorbed by other objects, resulting in a lower power quality tone. If this product can be combined with the floating touch technology, users can control the volume of the speaker through gestures for a more extreme experience.

In fact, there are many applications of the floating touch technology: merchants can display products in the window, and customers can feel the real effect of the products without entering the store; in-vehicle equipment can recognize the driver's gestures through the floating touch technology to improve the driving experience; It can make the medical system more perfect and reduce the chance of being exposed to germs; it can work in smart homes, and you can control home appliances through gestures, etc.

The floating touch technology is not yet mature, there are many areas that need to be improved, and it cannot be put into use on a large scale. However, the floating touch technology will bring a new idea to the application scenarios of smart devices, and even subvert the traditional way of human-computer interaction. Whether it is a gimmicky technology or an innovative application, we will wait and see.

Reviewing Editor: Li Qian

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