Sensors on a HUAWEI phone and their functions

What does a sensor do?

A sensor is a component used in mobile devices, the purpose of which is to detect changes in the environment (such as changes in brightness, magnetic fields, temperature, and gravity) and movement (such as the device being moved, flipped, or picked up), and convert them into electronic signals that can be processed by the device.

A mobile device sensor consists of precision components, which are sensitive to sources of external interference and physical factors. Avoid dropping your device or using it in environments with strong magnetic fields, abnormal humidity, extreme temperatures, or other unfavourable factors to avoid damaging its sensors.

Sensors come built-in with the device and cannot be automatically disabled. However, for certain scenarios such as screen rotation and positioning, you can disable the sensors from the drop-down menu.

Common mobile device sensors

1. Ambient light sensor

Function: Automatically adjusts the screen brightness of your device according to the amount of ambient light, making it more comfortable to look at the screen. The sensor not only supports automatic white balance (AWB) when taking photos, but also works with the proximity light sensor to prevent misoperations when, for example, the device is in your pocket.

How it works: The sensor generates strong or weak currents according to the amount of ambient light it senses, and the device increases or decreases the screen brightness accordingly. Please note that using a non-official protective case or unmatching protective film may block the ambient light sensor and affect its functions.

2. Proximity light sensor

Function: Detects the presence of nearby objects. Equipped with a proximity sensor, your device automatically turns off the screen when it detects that it is close to your ear. This helps prevent possible misoperations.

How it works: The sensor consists of an infrared LED light and an infrared radiation (IR) detector, and is generally located at the top of the screen and near the receiver. It detects the distance between an object and the device by calculating changes in the infrared light signals it receives. The working range of a proximity light sensor is generally 10 cm.

3. Proximity sensor

Function: Determines whether the device is close to or far away from an object (such as your ear during a call). For example, when you bring your phone to your ear, the screen turns off, and it turns on when you move your phone away from your face.

Note: Both proximity sensors and proximity light sensors are types of distance detection sensors.

4. Gravity sensor (accelerometer)

Function: Allows your device to automatically switch between landscape and portrait modes, count your daily steps, identify viewing orientation, use compass apps, and recognise motion gestures (such as picking up and flipping your device). For example, you can use your device's gravity sensor to control a moving ball or steer a race car in games, shake to switch songs, flip to mute ringtones, and so on.

How it works: The sensor measures changes in the distance between the capacitance plates caused by motion on three axes (X, Y, and Z), and determines the instantaneous acceleration and deceleration forces accordingly.

5. Gyroscope

Function: Allows you to play somatic games with your device, move your device to switch the view in games, and navigate when GPS services are not available. The gyroscope is also used in VR activities, 3D photography, panoramic navigation, and so on. (Some models do not have this sensor.)

How it works: A gyroscope is a device consisting of a rapidly spinning wheel set in a framework that permits it to tilt freely in any direction. The momentum of such a wheel causes it to retain its attitude when the framework is tilted, and is therefore used to measure or maintain orientation and angular velocity. Generally, a three-frame gyroscope is used on a device, which can simultaneously determine positions, motion tracks, and accelerations in six directions.

6. Compass

Function: Provides compass and map navigation functions to help locate positions more accurately. (Some models do not have this sensor.)

How it works: The Hall or magnetoresistance principle detects the size and direction of the magnetic field, and determines the magnetic field strength based on the three-axis reading of the sensor. The direction of the device can then be determined. Sometimes you need to shake or rotate your device for the compass to work properly. To ensure the accuracy of measurement results, avoid placing your device with magnetic objects.

7. Hall effect sensor

Function: Used in Smart cover mode, where your device automatically locks the screen when you close the flip cover, and unlocks the screen when you open the flip cover. (Some models do not have this sensor.)

How it works: In a Hall effect sensor, a conductor has a current applied along it. When the conductor is placed in a magnetic field perpendicular to the direction of the electrons, they will be deflected from a straight path. As a consequence, one plane of the conductor will become negatively charged and the opposite side will become positively charged, resulting in voltage differences. Please note that the sensor functions may be affected if you use a non-official flip cover.

8. Barometer

Function: Corrects altitude measurement errors to narrow down the deviation to about 1 metre and works with your device's GPS to find your altitude when you are under a flyover or inside a high-rise building. (Some models do not have this sensor.)

How it works: Consisting of a rheostat and a capacitor, a barometer measures the atmospheric pressure by calculating changes in electrical resistance and capacitance.

9. Infrared sensor

Function: Detects remote control signals and proximity light.

How it works: Using the characteristics of infrared LEDs, the sensor emits infrared light to exchange data with other devices or measure distances.

10. Fingerprint sensor

Function: Verifies your fingerprint for screen unlock and making payments.

How it works:

• Capacitive fingerprint sensors, commonly used on devices, sense the electrical current produced by finger touches and generate an image of the ridges and valleys that make up a fingerprint. The sensor then compares the image with the stored version on the device.
• In-screen fingerprint sensors (optical fingerprint sensors) sense the fingerprints using light reflections. They are used with OLED screens where spacing between pixels of an OLED allows for light transmission. When you tap the fingerprint sensor icon, the OLED illuminates the touched area. The in-screen sensor underneath the screen then grabs an image of the fingerprint that is projected onto the sensor. The sensor then compares the image with the stored version on the device. Currently, all products that support optical in-screen fingerprint recognition use OLED screens.
  

  OLED is short for organic light-emitting diode. The principle is that an organic light emitting layer is sandwiched between the two electrodes, and when electrons at the positive and negative electrodes meet in the organic material, the electrons emit light.

11. Flicker sensor (multispectral sensor)

Function:

1. Detects the frequency of the ambient light source to ensure that the exposure time delivered to the camera can match the brightness fluctuation of the ambient light source, avoiding bright and dark stripes caused by different exposure between frames.

2. Detects the light intensity for evaluating the ambient brightness before the camera module starts streaming, to ensure that each camera module has a proper exposure when it turns on.

How it works: The sensor uses highly sensitive photoelectric elements to capture the periodic light intensity fluctuations (flickers) of the light source, converts these fluctuations into electrical signals, extracts key parameters such as the flicker frequency and light intensity, and then outputs the detection result based on the thresholds for use by upper-layer apps in specific scenarios.