Home  Sensors

Dec 3 2019

What Sensors Are In The Phone?

1. Introduction

The development speed of smart phone technology is unimaginable, which includes sensor technology. Sensors in mobile phones have the ability to make a big difference in our way of life.

Sensors in mobile phones refer to those components that can be sensed by chips, such as response distance, light value, temperature value, brightness value and pressure value. Like all electronic components, these sensors are getting smaller and smaller, with stronger performance and lower cost.

Through the various data collected by the sensor, through the analysis and calculation of the program software of the mobile phone, various applications are generated. Today's mobile phones have provided extremely convenient functions in our social, financial payment, sports monitoring, entertainment, learning and other aspects.

Sensors in the phone

2. Types of sensors in the phone

. Acceleration sensor

The concept of acceleration sensor and gravity sensor overlap slightly, but in fact, they are different. Acceleration sensor is measured in multiple dimensions, which refers to the acceleration values in X, y and Z directions. It mainly measures some actions of instantaneous acceleration or deceleration. For example, measuring the speed and direction of the mobile phone, when the user holds the mobile phone, it will swing up and down, so that the acceleration can be detected to change back and forth in a certain direction, and the steps can be calculated by detecting the number of times of the change back and forth. In the game, the acceleration sensor can trigger special instructions. This sensor is also used in some daily applications, such as shaking and cutting songs, turning and muting.

The power consumption of acceleration sensor is small but its accuracy is low. Generally used in mobile phones, it can be used to measure steps and judge the direction of mobile phones.

. Gravity sensor

The gravity sensor is realized by piezoelectric effect. There is a heavy object and piezoelectricity piece integrated in the gravity sensor. The horizontal direction is calculated by the voltage generated in the two orthogonal directions. The gravity sensor used in the mobile phone can be used to switch between horizontal and vertical screen directions.

In some games, gravity sensors can also be used to achieve more interactive control, such as balance ball, car games and so on.

. Light sensor

The use of light sensor

The light sensor is similar to the eye of a mobile phone. The human eye can adjust the light entering the eye in different light environment. And the light sensor can let the mobile phone sense the intensity of the ambient light, which is used to adjust the brightness of the mobile screen. Because the screen is usually the most power consuming part of the mobile phone, the use of light sensors to help adjust the brightness of the screen can further extend the battery life. The light sensor can also be used with other sensors to detect whether the phone is placed in the pocket to prevent accidental contact.

. Proximity sensor

The use of proximity sensor

It is composed of an infrared LED lamp and an infrared radiation light detector. The distance sensor is located near the handset of the mobile phone. When the mobile phone is close to the ear, the system uses the distance sensor to know that the user is on the phone, and then turns off the display to prevent the user from affecting the call due to misoperation. The working principle of the distance sensor is that the invisible infrared light emitted by the infrared LED is reflected by nearby objects and detected by the infrared radiation light detector. The distance sensor is usually used with the light sensor.

. Magnetism Sensor

The magnetic field sensor uses the magnetoresistance to measure the plane magnetic field, so as to detect the intensity and direction of the magnetic field. Magnetic field sensor is usually used in the common compass or map navigation to help mobile phone users achieve accurate positioning.

Through the magnetic field sensor, you can obtain the magnetic field intensity of the mobile phone in X, y and Z directions. When you rotate the mobile phone until the value in only one direction is not zero, your mobile phone points to the right south. Many compass applications on mobile phones use the data of this sensor. At the same time, the specific orientation of mobile phone in three-dimensional space can be calculated according to the different magnetic field intensity in three directions.

. Gyroscope

Gyroscope can measure the angular velocity along one or several axes, which is an ideal technology to supplement the function of MEMS accelerometer. In fact, if the accelerometer and gyroscope are combined, the system designer can track and capture the complete action of 3D space, and provide a more real user experience, accurate navigation system and other functions for end users. "Shake and shake" function in mobile phone (for example, shaking mobile phone can draw lots), body sensing technology, as well as VR angle adjustment and detection are all applied to gyroscopes.

The gyroscope sensor is a necessary component for some induction games. With this sensor, the interaction of mobile games has a revolutionary change. Users can feedback the game with multi-directional operation of their bodies, not just simple buttons.

Usually, the standard mobile phone is equipped with three-axis gyroscope, which can track the displacement changes in six directions. The three-axis gyroscope can get the angular acceleration of the current mobile phone in X, y and Z directions, which is used to detect the rotation direction of the mobile phone. Some functions of turning the mobile phone and answering the phone are realized by the change of angular acceleration.

. GPS position sensor

There are 24 GPS satellites running in a specific orbit above the earth. They will continuously broadcast their position coordinates and time stamps(the total number of seconds since January 1, 1970, 00:00:00 GMT) to all parts of the world. The GPS module in the mobile phone starts from the instantaneous position of the satellite, and calculates the distance between the mobile phone and the satellite by the time difference between the time stamp of the satellite transmitting coordinate and the time of receiving. It can be used for positioning, speed measurement, distance measurement and navigation and so on. 

GPS module is mainly used to receive the satellite coordinate information through the antenna to help users locate. With the popularization of 4G network, GPS is used in more scenarios, such as remote location monitoring with intelligent hardware, or location search after device loss.

Ⅷ. Hall Sensor

The function principle of Hall sensor is hall magnetoelectric effect. When the current passes through a conductor located in the magnetic field, the magnetic field will produce a force perpendicular to the direction of electron motion on the electrons in the conductor, thus generating potential difference at both ends of the conductor.

The main function of the hall sensor installed on the mobile phone is to use the smart leather case (magnetic leather case). After the leather case is buckled, the screen will display a small window interface in the small window left on the leather case, which is used to answer calls or read short messages.

Ⅸ. Air pressure sensor

The use of air pressure sensor

When the air pressure changes, the value of resistance or capacitance will change, so as to measure the air pressure data. GPS can also be used to measure altitude, but there will be an error of about 10 meters. If the air pressure sensor is installed, the error can be corrected to about 1 meter, which is helpful to improve the accuracy of GPS (Global Positioning System).

In addition, when some outdoor applications need to measure air pressure, the mobile phone with air pressure sensor can also be used. In IOS health applications, you can calculate how many floors you have climbed.

. Heart rate sensor

The use of  heart rate sensor

Irradiate fingers with high brightness LED light, because the brightness (the depth of red light) will change periodically when the heart sends blood to capillaries. Then capture these regular changes through the camera, and transfer the data to the mobile phone for calculation, and then judge the heart contraction frequency to get the number of heart beats per minute.

The user's heart rate data is obtained by detecting the number of pulsations per minute of the blood vessels on the user's fingers. Heart rate sensors are common in wearable devices.

. Blood oxygen sensor

The use of blood oxygen sensor

Like heart rate sensor, hemoglobin and oxyhemoglobin in blood have different absorption ratio for red light. Infrared light and red light LED are used to irradiate fingers at the same time, and the absorption spectrum of reflected light is measured to measure blood oxygen content. Blood oxygen sensors can be used in sports or health applications.

. UV sensor

The use of UV sensor

The photoelectric emission effect of some semiconductors, metals or metal compounds will release a large number of electrons under ultraviolet irradiation. The ultraviolet intensity can be calculated by detecting this discharge effect. UV sensor is also used in the field of sports and health and in detecting radiation levels in the environment.

At present, there are few mobile phones using this kind of sensor, and the stability of the measurement needs to be further observed.

XIII. Temperature sensor

Many smartphones are equipped with temperature sensors, and some have more than one. The difference is that their purpose is to monitor the temperature inside the phone and the battery. If it is found that the temperature of a certain part is too high, the mobile phone will be turned off to prevent damage. In terms of extended functions, the temperature sensor can also detect the temperature change in the outside air, even the user's current temperature.

   XIV. Fingerprint sensor

The use of fingerprint sensor

At present, the mainstream technology is capacitive fingerprint sensor, but ultrasonic fingerprint sensor is also gradually popular. When the capacitive fingerprint sensor works, the finger is one pole of the capacitance, and the other is a silicon chip array. Through the micro current generated between the human body's micro electric field and the capacitance sensor, the distance between the fingerprint's peak and valley and the sensor forms the capacitance height difference to describe the fingerprint pattern.

The principle of ultrasonic fingerprint sensor is similar, but it will not be interfered by sweat and oil, and the recognition speed is faster. It can be used in mobile phones to unlock, encrypt, pay and so on. It can automatically collect user fingerprint to protect privacy, which is usually used as a security measure.

3. Integrated application of sensors in the phone

Nowadays, the technology level of smart phones is rapidly updated, which is largely due to the innovation and breakthrough of sensor technology in mobile phones. With the integrated application and software support of basic sensors, mobile phone researchers have developed many cool mobile phone functions.

Super safe 3D ultrasonic fingerprint recognition

The mobile phone integrates Xiaolong 820 chipset and Xiaolong sense ID. Among them, Xiaolong sense ID adopts the latest ultrasonic technology developed by Qualcomm to realize 3D fingerprint recognition.

Fingerprint press recognition technology has become the standard equipment of some smart phones. Different from the previous technology, Qualcomm snapdragon sense ID can work even when there is a little dirt or moisture in the user's fingers, and can even penetrate glass, aluminum, stainless steel, sapphire, plastic and other equipment for identification. This means that mobile phone manufacturers can integrate sensors and devices without having to make fingerprint identification units into a single button.

Therefore, ultrasonic fingerprint recognition technology can be put into the screen window of the flat panel. In addition, in terms of security, it has been greatly improved. Ultrasound has been used in the field of professional biometrics for a long time. It can penetrate the epidermis and detect the three-dimensional details of fingerprint, making it difficult for hackers to copy fingerprint and invade users' mobile phones.

Iris recognition of mobile phone

Iris recognition of mobile phone

The iris of human eye is more complex than fingerprint, so it is safer to use iris recognition to unlock mobile phone than fingerprint recognition. Users only need to capture the eyeball through a special app, log the iris pattern of the eye onto the terminal, and then they can use it safely. Iris mobile phone will become the wallet for everyone to pay, the gold card of the bank, the key to open the door, the certificate for customs clearance and the evidence for medical insurance, opening a new generation of Internet identity authentication.

The mobile phone's built-in micro iris recognition product consists of imaging module, lighting module and software algorithm. It can scan the user's iris features through the built-in camera, and the user only needs to stare at the screen for a short time. The effective recognition distance is 20 ~ 30cm, and the recognition speed is 1s. Based on the capsaic security chip and metacentric dual operating system independently developed by Spreadtrum, the iris recognition scheme is optimized from the aspects of system imaging, feature description and matching, security and anti-counterfeiting, user interaction, etc., to achieve accurate recognition.

RWB technology creates intelligent and beautiful image

The mobile phone with RWB technology is equipped with f1.8 aperture and 6p lens. Compared with the photos taken by the previous RGB technology models, the noise reduction ability is increased by 80%, the sensitivity is increased by 40%, and the area is reduced by 23%. The smaller rear camera mirror volume is used to obtain more light, and the details under weak light will be better.

The image sensor of Bayer array usually uses RGB (red, green and blue) technology. On average, the whole sensor will block two-thirds of the incident light, resulting in a great waste. RWB (red, white and blue) has the greatest improvement compared with the traditional Bayer array sensor, which is the high sensitivity shooting performance. As the green pixel is replaced by the white pixel, the effective light intensity received by the sensor almost doubles, and the RWB's high sensitivity index has also been significantly improved.

Leica dual camera

Leica Summit Series dual lens with better brightness and clarity makes it easier to take photos and videos. The rear 12 megapixel black-and-white and color dual cameras have more than just two 12 megapixel lenses. In the process of photographing, the dual cameras work at the same time, and the black and white lens capture the details to make the image clearer; the color lens capture the color to make the color fuller, and the image synthesis algorithm makes the details and the colors more integrated, so the picture is lifelike and amazing.

By using the hybrid focusing technology of laser focusing, depth focusing and contrast focusing, we can take the wonderful pictures with clear picture and clear layers in an instant.

Mobile phone for comprehensive health exercise monitoring

This mobile phone attaches great importance to the health of users. It is equipped with ten major professional sensors, with low power consumption, which can realize users' 24-hour use of professional sports applications. In addition, more sensors allow the phone to restore the user's real movement, accurate to three steps of movement, while also measuring heart rate, blood oxygen and ultraviolet. With the support of the application algorithm, the user's stride and stride frequency can also be accurately identified.

3D visual sensory experience of eye tracking technology

The concept of "full display mobile phone" has two cameras in front of it. One is used for taking photos like ordinary mobile phones, while the other is used for eye tracking and capturing the position of human eyes. According to your eye position and pupil distance, a reasonable visual angle image matching the position of human eyes is customized and generated in real time. Whether it's left and right or front and back movement, you can get comfortable and clear 3D visual sensory experience all the way.

"One screen, two cores and three cameras" is standard for full display mobile phones. ‘One screen’ is the naked eye 3D cylindrical grating LCD screen, users can experience the shock of 3D and VR vision without wearing 3D glasses, and they can realize the free switching of 2D / 3D. ‘Two cores’ is that in addition to the CPU, there is an independent VR visual motion chip to improve the 3D / VR rendering speed. ‘Three cameras’ is that in addition to conventional cameras, eye tracking cameras are added.

⑥ Video integrated mobile phone’s free conversion of 2D / VR

The mobile phone realizes the integration of VR camera and mobile phone. It is equipped with four cameras, two at the front and two at the back, which can meet the demand of 360 degree panoramic shooting, realize 3D stereo effect, and also can freely switch between VR lens and 2D plane lens at the same time.

The pixels of CMOS image sensor in VR camera module reach 26 million, and Sony photosensitive device is used. The thickest part of the camera module of ultra-thin VR panoramic lens is only 23.8mm, which is the thinnest mobile VR camera module in the world. VR mobile camera uses a single binocular zigzag two in one super wide angle camera module. This VR camera module contains two imaging systems with the same structure. Each imaging system is composed of a 200 degree super wide angle lens and an imaging sensor. The lens optical path adopts 90 degree zigzag double optical path design. The optical axis of the two cameras is the same, greatly reducing the lens volume to achieve ultra-thin and ultra light integrated structure.

VR camera module also integrates the front and rear VR camera scenes into a sphere through image recognition, splicing and other algorithms, so that the pixel size, color, brightness and other parameters of the two hemispheres are the same, which is the first in terms of technology.

4. Summary

The development of sensors in the future is sure that they will know more about the surrounding environment, that is to say, the types of sensors will be far more than these. The bolder assumption is that in the future, sensors will not only perceive, but also have certain processing capacity. What sensors transmit is not only data, but also some intelligent operation and judgment.

In terms of sensor technology, it is the common understanding of the whole industry that the sensor integration is getting higher and higher. The higher integration degree leaves more possibilities for the expansion of sensors, and greatly saves the equipment space, which is more conducive to the development of mobile devices towards portability.

I believe that in the foreseeable future, the perception of our mobile phone to users will be more accurate, and its application in the future will be far richer than we think now.

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