In recent years, iPhone has gained high praise for its high performance and unique user experience. However, do you know how iPhone realizes its powerful functions? Actually, we can owe those functions to sensors adopted in iPhone such as capacitive touch sensor, ambient light sensor, proximity sensor, accelerometer, magnetometer, gyroscopic sensor, etc. Here, we’d like to make a brief introduction to those sensors.
1. Capacitive touch sensor The iPhone’s capacitive touch screen is preferred by many users. Well then, what is the glamour of capacitive touch screen? As a matter of fact, the capacitive touch sensor helps users get unique experience. It is believed that users who have used resistive touch screen must know the functional limitations and defects of the resistive touch sensor. On resistive touch screen, users can only conduct simple single-point movements such as clicking or dragging. That is because resistive touch sensor is capable of identifying one touching point only, while it may give wrong judgments when there are more than two touching points. Unlike resistive touch screen, capacitive touch screen is equal to identifying multiple touching points. The electro-conductivity makes capacitive touch sensing possible. Once your electro-rich fingers contact screen glass, the capacitive sensing system may be activated. Then,
coupling capacitance is produced. By making use of the generated coupling capacitance, sensor controller will gain the exact position of touching point via precise calculation.
2. Accelerometer It is believed that motion-controlled games and location-based service of iPhone leave deep impression on users. We can owe those functions to accelerometer adopted in iPhone. Mechanical and optical technologies are extensively used in accelerometer. Since accelerometer is able to sense the orientation of the phone and change the screen accordingly, users can easily switch between portrait and landscape mode. That is why users can realize photo browsing, web browsing and music playing in different orientations such as upright, left and right.
3. Proximity sensor iPhone users may have noticed that the backlight and finger-touch screen are disabled automatically when users put the iPhone close to their ear. In this way, users can save power and avoid misoperations. Actually, the function is based on proximity sensor which owns the ability to sense the movements of the objects which are approaching it. Proximity sensor was once applied in aerospace field and industrial field. With the miniaturization and decrease of power consumption, proximity sensor has been applied in electronic field. Among various proximity sensors, Si1143 produced by Silicon Labs is renowned.
4. Ambient light sensor Ambient light sensor is not a brand new product. Decades ago, light sensitive resistance and photodiode were used to read ambient light. As more and more attention is paid to environmental-friendliness and enhancement of intelligence of electronic products, the application of ambient light sensor gets wider. The ambient light sensor in iPhone serves two purposes: on the on hand, it can automatically control backlight of monitor according to the surrounding so as to lower power consumption. On the other hand, ambient light sensor can improve the softness of images displayed by monitor. When ambient light reaches high level, ambient light sensor-based LCD will adjust to high-brightness level.