Basic smartphone sensors – what are they and why are they needed? Light sensor - what is it
What components can be noted when looking at the body of a smartphone? This is, first of all, a fairly large display, several keys below it, a microphone and several camera windows. In addition, at the ends of the device there will probably be a microUSB port, a volume rocker, a headphone output and a lock key. But is this where the device components end? Of course not. Inside it there was room for several processors, many circuits and, most importantly, several different sensors. Which of them can be found in modern devices? Let's find out.
Accelerometer
According to our colleagues from phonearena, the accelerometer is one of the most common sensors. According to the classical definition, its task is to calculate the difference between the true acceleration of an object and the gravitational acceleration.
You've probably heard a lot about how to use it. Without an accelerometer, smartphones would hardly change from portrait to landscape orientation and could do without user clicks in all kinds of racing simulators.
Gyroscope
The gyroscope also provides data about the device's position in space, but does this with much greater accuracy. It is thanks to his help Photo app Sphere finds out how many degrees the smartphone was rotated and in what direction it was done.
Magnetometer
That's right, the magnetometer is designed to determine magnetic fields. Without it inside the smartphone, the compass app would hardly be able to figure out where the North Pole is.
This sensor is a combination of an infrared diode and an infrared radiation detector. The principle of its operation is incredibly simple. The diode emits radiation invisible to the human eye, and the detector tries to catch its reflection. The smartphone blocks the display exactly when the beam hits back.
Light sensor
Changing the brightness of the display yourself is another task, right? Another thing is the auto-brightness function, which changes the screen brightness level depending on the surrounding radiation. This may be, as you probably already guessed, thanks to the light sensor.
It is worth noting that some representatives of the Galaxy line from South Korean manufacturer Samsung use an updated light sensor. Its main feature is the ability to measure the proportion of white, red, green and blue light for further adjustment of the picture on the screen.
Barometer
No, this is not a mistake. Some smartphones actually have a built-in barometer to measure atmospheric pressure levels. Among the first devices with this feature were XOOM and Samsung Galaxy Nexus.
The barometer is also used to measure altitude above sea level, which increases the accuracy of the GPS navigator.
Thermometer
You may be surprised, but a thermometer is found in almost every smartphone. The only difference is that the latter is designed to measure the temperature inside the device. However, there were exceptions. The Galaxy S4 had a thermometer to measure the temperature outside.
Air humidity sensor
In this, by the way, the fourth representative of the Galaxy S line also succeeded. Thanks to this sensor, the fourth Galaxy reported the level of comfort - the ratio of temperature and humidity.
Pedometer
Despite the rather unobvious name, the task of the pedometer is to determine the number of steps taken by the user. Yes, just like most smartwatches and fitness bracelets. One of the first devices with a real pedometer was the Nexus 5.
Fingerprint scanner
You have, of course, heard about this. Thanks to the fingerprint scanner, you can not only reduce the time it takes to unlock your smartphone, but also reliably protect your data. Among the most popular devices with the notorious scanner are, HTC One Max and Samsung Galaxy S5.
Heart rate sensor
Since we're talking about the current South Korean flagship, we can't help but mention the heart rate sensor, designed to measure pulse. However, many users openly doubt the need for its implementation.
Harmful radiation sensor
It’s quite hard to believe, but in this world there really is a smartphone with a built-in sensor harmful radiation. The Japanese Sharp Pantone 5 can boast of its presence. After launch special application the latter demonstrates the ambient radiation levels. Unexpected, isn't it?
As a result, there were as many as 12 sensors. Which ones do you use most often?
A modern smartphone is a complex high-tech computing device that is more powerful than thousands of on-board computers that launched the Apollo missions to the Moon half a century ago. There are also almost more sensors installed on board flagship mobile phones than on board this very Apollo. Each of them quietly but conscientiously performs their work. What do all these smartphone sensors do, and how do they work? Read on for more details.
The light sensor in a smartphone is located on the front panel, usually near the earpiece (there are exceptions). Structurally, it is a semiconductor sensor sensitive to photon flux. Depending on its intensity, the sensor controls the display backlight in order to use battery power more efficiently. Also it can perform auxiliary function for other tasks, working with a proximity sensor.
Proximity sensor
This is an optical or ultrasonic sensor that determines whether there are objects in front of the screen. It sends a very weak light or sound pulse, and if it is reflected, it registers the reflected signal. Due to this it is carried out automatic blocking screen in talk mode or when turning the smartphone display down. Traditionally, the proximity sensor is calibrated in such a way that it registers only 2 states: “ foreign object closer than N (usually 5) centimeters” and “foreign object further than N cm”.
Accelerometer
This smartphone sensor is located on a circuit board and is a miniature electromechanical device that records the slightest movements. The responsibilities of this sensor include switching the orientation of the smartphone screen when tilted, controlling games, registering special control gestures (such as shaking or tapping the body), and also measuring steps (by counting rhythmic vibrations during walking).
A regular dual-axis accelerometer in a smartphone
There are two-axis and three-axis accelerometers. A feature of the accelerometer is that at rest, one of the axes will always show a value in the region of 9-10 m/s 2 (in a three-axis three-dimensional accelerometer). This is due to the fact that the Earth's gravity is on average 9.8 m/s 2 .
Gyroscope
The gyroscope is responsible for determining the movement and orientation of the smartphone in space. It also structurally represents a MEMS (microelectromechanical circuit) located on system board. Its areas of application overlap with those of the accelerometer. The main differences are that the gyroscope has noticeably greater accuracy and measures movement not in m/s 2, but in radians or degrees per second. Due to this, it can be used to track head turns in a VR headset, as well as more accurately implement gesture control.
MEMS gyroscope under a microscope
Magnetometer and Hall sensor
The magnetometer measures the quantity magnetic field the surrounding world. It also takes measurements in three-dimensional space (along three axes of Cartesian coordinates - X, Y and Z). The main function of a magnetometer is to more precise definition locations during navigation. In this mode of use it performs the function digital compass. Due to the fact that one of the axes, which is located in the plane with the North Pole of the Earth, registers a constantly increased background. The magnetometer helps to more accurately determine in which direction relative to north the smartphone is moving.
Smartphone magnetometer
A magnetometer is often called a Hall sensor, but these are not entirely identical concepts. We wrote more about the Hall sensor in another article. The differences are that the first is more universal and sensitive. The magnetometer is capable of measuring magnetic radiation, while only registering its presence/absence and decrease/increase. IN modern smartphones A separate Hall sensor is usually not installed, since a universal magnetometer completely covers its functionality.
One of alternative functions The magnetometer is to search for wiring in the walls. A live conductor generates a weak electromagnetic radiation, and the sensitivity of the sensor is units of microtesla. If you move your smartphone along the wall, the magnetic background will be increased where the cable is laid.
Gravity sensor
Measures the force of gravity of our planet in three-dimensional space. At rest (when the smartphone is lying on the table), its readings should coincide with the accelerometer: along one of the axes the gravitational force will be close to 9.8 m/s 2 . This sensor is usually not used on its own, but it helps the work of others. In navigation mode, it determines which side of the earth's surface is in order to quickly determine the correct position of the smartphone. When used in VR, the gravity sensor ensures the correct positioning of the image.
Linear acceleration sensor in a smartphone
The principle of its operation is almost identical to the accelerometer, the only difference lies in inertia. That is, the readings of this sensor do not depend on any global external factors(like gravity). The only thing it registers is the speed of the smartphone’s movements in space relative to its previous position.
The linear acceleration sensor is not capable of determining the position of the device in space (there is no reference to external landmarks), but this is not necessary (the gravity sensor and accelerometer do an excellent job of this task). The absence of reference to external landmarks allows you to rotate objects on the display without reference to these landmarks, for example, in games. Also, this sensor, in combination with others, increases the overall accuracy of movement detection.
Rotation sensor
It determines the direction and frequency of rotation of the smartphone relative to one of the axes of three-dimensional space. Like the acceleration sensor, it is independent and not tied to external reference points. Often performed as part of a single module with a linear acceleration sensor. Separately, as a rule, it is not used, but it allows you to adjust the operation of other sensors to improve accuracy. It also helps with gesture control, for example, by twisting the smartphone in your hand, the camera is activated.
Cutaway MEMS gyroscope
Temperature sensors
A modern smartphone is abundantly stuffed with digital thermometers. Structurally, they are a thermocouple: a resistor with two terminals, the resistance between which varies depending on the temperature. Since it is relatively primitive, it can even be implemented inside a semiconductor chip.
Every smartphone must have a battery temperature sensor. If it overheats, it turns off charging or reduces the output current to prevent the electrolyte from boiling, which leads to a fire or explosion. Thermometers inside the SoC are also common (from a couple of pieces to a dozen or more). They measure the temperatures of processor cores, graphics accelerators, and various controllers. Sometimes there are also ambient temperature sensors, but they are not widespread. The reason for this is low accuracy, since heat from the inside of the device and the user’s hands distorts the readings.
Pressure sensor (barometer) in a smartphone
The barometer on your smartphone measures atmospheric pressure (in mmHg, bar or pascals). It allows you to more accurately determine your location and altitude above sea level, since the pressure decreases as you rise. It can also be used as an altimeter, measuring altitude above sea level, but the accuracy leaves much to be desired, since atmospheric pressure changes with the weather. The function of adjusting the weather forecast in meteorological programs and widgets is even less in demand.
Hygrometer
A hygrometer measures air humidity. Its main purpose is obvious, but this sensor is not popular. In theory, it can be used to correct weather forecast data. Knowing the readings, you can also control the indoor climate by turning on a humidifier or dehumidifier. The only known smartphone with a hygrometer is the old Samsung Galaxy S4.
Heart rate monitor or heart rate sensor in smartphones
The heart rate monitor is capable of measuring the frequency and rhythm of heart contractions. During sports, it makes it possible to monitor the work of the heart and adjust the load to increase the effectiveness of training. The disadvantage of a heart rate monitor is the need for close contact of the smartphone with a part of the body in which the blood vessels are close to the surface (for example, fingers) in order to catch the slightest pulsations. Because of this, it has not gained popularity in smartphones, but is found everywhere in smart watches and fitness trackers.
Smartphones today are equipped with many sensors, the operation of which is often invisible. At the same time, their absence sharply reduces the functionality of the phone. At presentations of new products they are mentioned in passing, although each of the available sensors makes working with a smartphone more convenient and easier.
In this short article, we will look at the main sensors that are an integral part of most modern smartphones and their purpose.
Accelerometer
The accelerometer is the most popular sensor in smartphones today. It measures the acceleration of the body in space and is responsible for automatically rotating the image on the display.
Absolutely all modern smartphones are equipped with this sensor, and its job is to automatic change screen orientation when rotating the device.
Gyroscope
The gyroscope in a smartphone determines the speed of angular rotation. Thanks to this sensor, the user can control the game by turning the gadget. It is also used in photography and for coordinating drones. It is also extremely useful and can be found almost everywhere.
Magnetometer (Hall sensor)
Magnetometer ( magnetic compass) is not found in all smartphones. This sensor measures the level of the magnetic field and is used for comfortable work with navigation services and in the case of launching a digital compass. Working with cases that allow you to unlock your smartphone when you open the accessory also depends on the presence of a magnetometer.
Many smartphones do not have a hardware magnetometer, which prevents the use of appropriate accessories. They use a so-called digital (software) compass, which is used in navigation, but is less accurate.
Barometer
The barometer built into your smartphone will allow you to accurately determine atmospheric pressure. With this sensor it is easy to find out your current position above sea level. The presence of a barometer significantly increases the accuracy of GPS data, but is a privilege of top-end expensive smartphones.
Pedometer
A pedometer or pedometer helps monitor the distance traveled, expressed in the number of steps. The presence of this sensor demonstrates that the smartphone owner pays attention to physical activity and his health.
A separate step sensor may only be available in some smartphones and smart watch, aimed specifically at athletes and people who want to lead a more active lifestyle. In other smartphones, steps are counted using standard sensors and special sports programs, but a little less accurately.
Proximity sensor
The proximity sensor is a mandatory module that locks the screen during a call from random clicks(when the screen is applied to the cheek). In addition, in some more expensive models A gesture control system using a proximity sensor has been successfully implemented.
Light sensor
A light sensor is installed to measure the light around the smartphone. Based on the information received from it, the smartphone can automatically set a comfortable screen brightness. This is an extremely useful sensor that makes it easier to use your smartphone without the need to constantly manually adjust the brightness, but may be missing in some budget smartphones.
Outdoors, in bright light, the screen will be as bright and easy to read; indoors, the brightness will be reduced to an average level, and in the evening and in a darkened room, the backlight will be lowered to a minimum level that is gentle on the eyes.
Fingerprint sensor
In recent years, a fingerprint scanner has become a standard in modern smartphones. Using this unlocking method, you can deny access to the device or individual applications from strangers.
Unlocking your smartphone using a fingerprint sensor allows you to quickly gain access to the functionality of your smartphone and prevent access to personal data if it is lost or stolen.
The fingerprint scanner provides high level protect your smartphone, because unlike a password or graphic key Finding a way to unlock without a given finger is almost impossible.
Other sensors
There are also some other sensors such as thermometer, humidity sensor, heart rate sensor (heart rate sensor), harmful radiation sensor (radiation sensor). But they are extremely rare and their purpose is quite clear, so we will not dwell on this.
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Smartphone Xiaomi Redmi 4a
Smartphone Xiaomi Redmi 5
Smartphone Xiaomi Redmi 5a
The smartphone performs numerous functions that can be compared with those on a computer. However, given the purpose of this device, it also contains various sensors. With their help, the screen is automatically flipped when the phone’s position in space changes, the display turns off when the device approaches the ear, etc. In this article, we will understand what a light sensor in a smartphone is, where it is located, how it is configured and tested for functionality.
Light sensor in the phone
First of all, let's talk about the purpose of this sensor. It is used for automatic adjustment display backlight level. In other words, this sensor determines the amount of light surrounding the smartphone and, in accordance with the indicator, sets the brightness of the screen. So, at night it will be at a level close to the minimum, and when directly hit sun rays- at the maximum value.
In addition to making the phone easier to use, the light sensor helps save battery power. Users rarely change the brightness of the display depending on environmental conditions, so only once set value persists day and night. And so, by turning on automatic adjustment, you don’t have to worry about setting the appropriate backlight level.
Where is the sensor located?
Now let's say a few words about the location of the light sensor in a smartphone. Despite differences in design, almost every manufacturer mobile devices installs this component at the top of the front of the device. This place is usually located next to conversational speaker and a proximity sensor.
Externally, the sensor is almost invisible, revealing itself only as a black circle of small diameter. Its location can be determined experimentally:
- enable automatic brightness adjustment;
- cover the intended location of the sensor with your finger;
- The screen brightness should decrease.
Will be useful
If the backlight level does not decrease, then your finger has hit the proximity sensor and you need to try another place.
Functionality check
If there is no automatic adjustment after turning it on or the response is too inaccurate, you need to check the functionality of the light sensor in your smartphone. This process is carried out software and includes the following steps:
Based on the data obtained, a conclusion is made regarding the performance of the element. A low change in the indicator when the sensor is closed and open indicates a problem. You will have to perform calibration or take your smartphone for repair.
Calibration
The information presented above about the light sensor in a smartphone allows you to understand what it is, where it is located and how it is checked. Now let's figure out how to calibrate.