【Repost】Understand the seven major sensors on smartphones in one article

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【Repost】Understand the seven major sensors on smartphones in one article [Copy link]

With the advancement of technology, mobile phones are no longer a simple communication tool, but a portable electronic device with comprehensive functions. Do you know the principles and uses of common sensors in mobile phones?

1. Geomagnetic sensor

25)]The compass function of smartphones uses the geomagnetic field and the built-in geomagnetic sensor of the phone to achieve geographic positioning. If the direction of the compass needle changes, it means that the geomagnetic field and the built-in sensor of the phone have worked, but in opposite directions. This situation may be caused by interference from a strong external magnetic field. For example, there is a strong magnetic field at a certain location, or other external factors are opposite to the geomagnetic field, which may cause the influence of this magnetic field. When climbing, you can change a position or lay the phone flat and move it in an 8-shaped shape to calibrate the compass.

2. Gyroscope

Principle: Angular momentum conservation. When the rotation axis of an object (gyroscope) that is rotating at high speed is not affected by external forces, the direction of the rotation axis will not change. The gyroscope is based on this principle and uses it to maintain a certain direction. The three-axis gyroscope can replace three single-axis gyroscopes and can simultaneously measure the position, movement trajectory and acceleration in six directions.

Use: body sensing, shake (shake the phone to achieve some functions), translation/rotation/movement. The phone can control the viewing angle in the game, VR virtual reality, and inertial navigation according to the movement state of the object when there is no GPS signal (such as in a tunnel).

3. Light sensor

Principle: When the photosensitive transistor receives external light, it will generate currents of varying strengths, thereby sensing the brightness of the ambient light.

Purpose: Usually used to adjust the brightness of the screen's automatic backlight, increase the screen brightness during the day, and reduce the screen brightness at night, so that the screen is clearer and less dazzling. It can also be used for automatic white balance when taking pictures. It can also be used with the distance sensor below to detect whether the phone is in a pocket to prevent accidental touches.

4. Distance sensor

Principle: The infrared LED emits infrared rays, which are reflected by close objects. The infrared detector measures the distance by receiving the intensity of the infrared rays. The effective distance is generally within 10cm. The distance sensor has both a transmitting and a receiving device, and is generally larger in size.

Purpose: Detect whether the phone is placed against the ear and is making a call, so as to automatically turn off the screen to save power. It can also be used to automatically unlock and lock the screen in leather case and pocket mode.

5. Gravity sensor

Principle: It is realized by using the piezoelectric effect. A heavy object and a piezoelectric sheet are integrated inside the sensor. The horizontal direction is calculated by the voltage generated in two orthogonal directions.

Purpose: Intelligent switching of horizontal and vertical screens of mobile phones, orientation of photos, and gravity sensing games (such as rolling steel balls). 6. Acceleration sensor Principle: Same as the gravity sensor, it is also a piezoelectric effect, and the direction of acceleration is determined by three dimensions, but the power consumption is lower, but the accuracy is low.

Purpose: step counting, mobile phone placement angle.

7. Magnetic field sensor

Principle: Anisotropic magnetoresistive material, when sensing weak magnetic field changes, will cause its own resistance to change, so the phone needs to be rotated or shaken several times to accurately indicate the direction.

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