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CatalogI IntroductionII What is Infrared?III Theoretical Principle of Infrared Temperature MeasurementIV The Principle of Infrared ThermometerV Differences in Accuracy of Different Types of Infrared Thermometers  5.1 Three Categories of Infrared Thermometers  5.2 Differences Between Mainstream Infrared Thermometers  5.3 Infrared Temperature GunVI Infrared Thermometer Accuracy And Factors Affecting Accuracy  6.1 Precision of Infrared Thermometer  6.2 Factors Affecting The Accuracy of The Infrared Thermometer MeasurementVII Factors to Consider When Choosing An Infrared ThermometerVIII How To Make Infrared Thermometers More AccurateIX One Question Related to Infrared Thermometers  9.1 Question  9.2 AnswerX FAQI IntroductionIn the past two months, due to the outbreak of Coronavirus Disease 2019 (COVID-19), output of infrared thermometers exceeded the whole year of last year, driving the shipments and demand for chips such as sensors, MCUs, and operational amplifiers. Infrared thermometer is a non-contact diagnostic technology that can scan and image the thermal radiation of objects and display data. It has the advantages of wide measurement range, fast temperature measurement, high accuracy and high sensitivity. With the widespread use of infrared thermometers, some users have doubts about its working principle and accuracy. This article will introduce how the infrared thermometer works, and explain its accuracy and the factors that affect it.Figure1. Infrared ThermometerII What is Infrared?Infrared is an electromagnetic wave with a wavelength between microwave and visible light. The wavelength is between 1mm and 760 nanometers (nm), which is invisible light longer than red light. Anything above absolute zero (-273.15°C) can generate infrared rays. Modern physics calls it heat rays. Medical infrared can be divided into 2 categories: near infrared and far infrared. Containing thermal energy, the sun's heat is mainly transmitted to the earth through infrared rays. Infrared is a part of the many invisible rays of the sun's rays. It was discovered by British scientist Herschel in 1800 and is also called infrared thermal radiation. It has a strong thermal effect. He split the sunlight with a prism, and placed thermometers on the ribbons of various colors in an attempt to measure the heating effect of light of various colors. It was found that the thermometer located outside the red light warmed the fastest.  Therefore, it is concluded that in the solar spectrum, there must be invisible light outside the red light, which is infrared. Can also serve as a medium of transmission. The wavelength of infrared light in the solar spectrum is greater than visible light, with a wavelength of 0.75 to 1000 μm. Infrared can be divided into three parts, namely near infrared, with a wavelength between (0.75-1) to (2.5-3) μm; mid-infrared, with a wavelength between (2.5-3) to (25-40) μm; far infrared , The wavelength is between (25-40) ~ l500μm.Figure2. InfraredIII Theoretical Principle of Infrared Temperature MeasurementIn nature, when the temperature of an object is higher than absolute zero, due to the existence of internal thermal movement, it will continuously radiate electromagnetic waves to the surroundings, including infrared rays with a wavelength range of 0.75µm ~ 100µm. Its biggest feature is that at a given temperature and wavelength, the radiant energy emitted by an object has a maximum value.  This substance is called a black body, and its reflection coefficient is set to 1; the reflection coefficient of other substances is less than 1, and is called gray body. Because the black body's spectral radiant power P (λT) meets Planck's law between the absolute temperature T, it shows that at the absolute temperature T, the radiant power of the black body per unit area at the wavelength λ is P (λT). According to this relationship, the relationship curve can be obtained as shown in the figure below: (1) As the temperature increases, the stronger the radiant energy of the object. This is the basis of the theory of infrared radiation and the design basis of a single-band infrared thermometer. (2) As the temperature rises, the radiation peak shifts to the short-wave direction (to the left) and satisfies the Wien shift theorem. The wavelength at the peak is inversely proportional to the absolute temperature T, and the blue curve is the line connecting the peaks. This formula tells us why the high temperature thermometer works mostly in the short wave and the low temperature thermometer works mostly in the long wave. (3) The rate of change of radiant energy with temperature is larger at the short wave than at the long wave, that is, the thermometer working at the short wave has a relatively high signal-to-noise ratio (high sensitivity) and strong anti-interference. This is particularly important at wavelengths, especially for small targets at low temperatures.Figure3. Planck's Law of Blackbody RadiationIV The Working Principle of Infrared ThermometerThe infrared thermometer consists of the optical system, photodetector, signal amplifier, signal processing and display output. The radiation of the measured object and the feedback source is adjusted according to the modulator and input to the infrared detector. The difference between the two signals is amplified by the inverse amplifier and the temperature of the feedback source is controlled so that the spectral radiance of the feedback source is the same as that of the object. The display indicates the brightness temperature of the object being measured.How does an Infrared Thermometer work?V Differences in Accuracy of Different Types of Infrared Thermometers5.1 Three Categories of Infrared ThermometersAccording to different uses and accuracy, infrared thermometers can be roughly divided into medical-grade infrared thermometers, consumer-grade infrared thermometers, and industrial-grade infrared thermometers. Strictly divided, medical-grade infrared thermometers have the highest accuracy requirements. The accuracy needs to be between 0.1 and 0.2 degrees. High-precision infrared ear thermometers can meet the medical-grade temperature standards. However, to avoid cross-infection, hospitals use ear thermometers. One-time sheath is needed for warm guns; consumer grades are next, and accuracy around 0.5 can meet our daily temperature measurement needs. The accuracy is about 0.3 degrees, which belongs to the consumer-grade infrared thermometer; the industrial grade has the lowest, generally the maximum allowable error is more than ± 1 ° C, and the distance is far.5.2 Differences Between Mainstream Infrared ThermometersIn fact, whether it is a medical or industrial infrared thermometer, they use the same principle of receiving infrared waves from the human body, but the object distance ratio has been adjusted differently, and the surface temperature is measured. The normal forehead temperature is about 2-3 ° C lower than the temperature of the armpit, and the forehead is directly affected by the environment. It is for preliminary investigation and reference and cannot be used as a basis for medical diagnosis. In addition, the temperature of the ear and neck will be more stable than the temperature of the forehead and barely affected by the environment. This is one of the reasons why the ear thermometer is more accurate than the forehead.5.3 Infrared Temperature Gun The medical thermometer has been revised by software or the relevant range has been limited by the software before leaving the factory. The emissivity of a normal human body is 0.98 (the thermometer defaults to 0.95), so the measured result is about 34-35 ° C. All infrared products (infrared cameras) can correct the difference by changing the emissivity to 0.8 to avoid inaccurate body temperature when used by non-professionals; and industrial-grade thermometers provide more realistic feedback on temperature measurement. It shows the actual temperature detected.Figure4. Infrared Temperature GunVI Infrared Thermometer Accuracy And Factors Affecting Accuracy6.1 Precision of Infrared ThermometerThe accuracy of contact measurement is about 0.1 degrees. Compared with contact temperature measurement, the accuracy of non-contact temperature measurement is lower. The infrared thermometer with higher accuracy is about 0.2 degrees, and the worse temperature error is 1 degree. Even above 1 degree. In general, the accuracy of infrared thermometers is ± 2 ° C. Today, temperature measurement products such as handheld infrared thermometers on the market are easily affected by measurement distance and ambient temperature, and the measurement error is often around 1 degree.6.2 Factors Affecting The Accuracy of The Infrared Thermometer Measurement6.2.1 EmissivityAll objects reflect, transmit, and emit energy, and only the emitted energy can indicate the object's temperature. When the infrared thermometer measures the surface temperature, the instrument can receive all three kinds of energy. Therefore, all infrared thermometers must be adjusted to read only the emitted energy. Measurement errors are usually caused by infrared energy reflected from other light sources.  Some infrared thermometers can change the emissivity, and emissivity values for many materials can be found in published emissivity tables. Other instruments have a fixed pre-set emissivity of 0.95. The emissivity value is the surface temperature of most organic materials, paints or oxidized surfaces, which is compensated by applying a tape or flat black paint to the measured surface. When the tape or lacquer reaches the same temperature as the base material, measure the temperature of the surface of the tape or lacquer, which is its true temperature.Figure5. Emissivity6.2.2 Ratio of Distance To Light SpotThe optical system of the infrared thermometer collects energy from a circular measurement spot and focuses it on the detector. The optical resolution is defined as the ratio of the distance from the infrared thermometer to the object to the size of the measured spot (D: S). The larger the ratio, the better the resolution of the infrared thermometer and the smaller the spot size to be measured. 6.2.3 Field of ViewMake sure the target is larger than the spot size of the infrared thermometer. The smaller the target, the closer it should be. When accuracy is particularly important, make sure the target is at least 2 times the spot size.Figure6. Field of ViewVII Factors to Consider When Choosing An Infrared Thermometer(1) Temperature rangeThe temperature measurement range is actually the range of the infrared thermometer, and the range of different thermometers will be different. The temperature measurement range is generally -50 ~ 360 ° C, -30 ~ 380 ° C, -18 ~ 280 ° C, -32 ~ 450 ℃, -32 ~ 650 ℃, -32 ~ 1050 ℃, etc., and the range for measuring body temperature is generally 35 ~ 42.5 ℃. You need to choose the appropriate range according to the temperature range of the measured object. (2) Measurement accuracyMeasurement accuracy is the only indicator to ensure the accuracy of the measurement, and it is also a key indicator to determine the performance of the infrared thermometer. Accuracy is usually expressed as ± X ℃ or ± X%. The smaller the value, the higher the accuracy. (3) Display resolutionThe display resolution is the last digit of the temperature display, usually 0.1 ° C or 0.1 ° F. (4) Optical resolutionThe optical resolution is the ratio of the distance D from the thermometer to the target to the diameter S of the measurement spot, that is, the ratio of the distance to the spot diameter D; S, D: S, the greater the accurate temperature measurement distance. In order to obtain accurate temperature readings, the distance between the thermometer and the test target must be within a suitable range. If the pyrometer must be measured away from the target due to environmental conditions, and a small target is to be measured, a pyrometer with high optical resolution should be selected. (5) EmissivityEmissivity is the ratio of the energy radiated by an object at a specific temperature to the energy radiated by an ideal radiator at the same temperature. Different objects have different emissivities. Some infrared thermometers have a fixed emissivity of 0.95, while others are adjustable. The emissivity of the infrared thermometer can be adjusted according to the material of the measured object to ensure the accuracy of the measurement results. (6) Response timeThe response time is the time it takes for the infrared thermometer to reach 95% of its final reading. It represents the speed at which the infrared thermometer responds to changes in the measured temperature. The response time of the new infrared thermometer can even reach 1ms. If the target moves fast or measures a fast-heated target, a fast-responding infrared thermometer should be selected; otherwise, a sufficient signal response cannot be achieved, which will reduce the measurement accuracy.Figure7. Infrared ThermometerVIII How To Make Infrared Thermometers More Accurate(1) Accurately determine the emissivity of the measured object;(2) Avoid the influence of high-temperature objects in the surrounding environment;(3) For transparent materials, the ambient temperature should be lower than the temperature of the measured object;(4) The thermometer should be vertically aligned with the surface of the measured object. Under no circumstances should the angle exceed 30 ° C.(5) Can be applied to the temperature measurement of bright or polished metal surfaces, and cannot be measured through the glass;(6) Correctly follow-off coefficient, the target diameter is full of field of view;(7) If the infrared thermometer is suddenly in a situation where the ambient temperature difference is 20 ° C or higher, the measurement data will be inaccurate, and then take the measured temperature value after the temperature is balanced. IX One Question Related to Infrared Thermometers9.1 QuestionWhat is infrared radiation?A. It's the transfer of energy by electromagnetic wavesB. The radiation given off by radioactive particlesC. Infrared radiation is a type of gasD. It is the reaction that occurs by freezing water9.2 AnswerA X FAQ1. How do you accurately use an infrared thermometer?Keep the Infrared Thermometer Close to the TargetThe Distance-to-spot ratio is the surface area being able to be detected compared to the distance taken from the target. As a rule of thumb, the closer you are to the target, the smaller the measurable surface area is, thus the more accurate the measurement. 2. How does the infrared temperature sensor work?These sensors work by focusing the infrared energy emitted by an object onto one or more photodetectors. These photodetectors convert that energy into an electrical signal, which is proportional to the infrared energy emitted by the object. 3. How accurate are thermal thermometers?Research has shown that, when used correctly, infrared or no-contact thermometers are just as accurate as oral or rectal thermometers. No-contact thermometers are popular among pediatricians, as kids often squirm around when trying to get a temperature read, but it also holds true in mass temperature screenings. 4. What is normal forehead temperature with an infrared thermometer?Normal forehead skin temperature can vary several degrees depending on your environment (indoors or out), exercise, perspiration, direct heat or air conditioning, etc. It would be normal to read an actual forehead skin surface temperature between 91F and 94F if using a general-purpose infrared thermometer. 5. Are infrared thermometers dangerous?As long as the Non-Contact Infrared Thermometers are used properly, they do not represent a risk of possible eye damage, as these Thermometers do not use lasers to measure body heat, the authorized thermometers measure infrared light; therefore they are not dangerous. 6. How far away should you hold an infrared thermometer?Usually, 6 inches is considered the ideal distance for using an infrared thermometer and correctly monitoring the temperature. 7. What is the benefit of using an infrared thermometer?IR thermometers are handy for use in measuring drafts and insulation breakdown. They can pick up hot spots in electrical systems and bearings and help monitor cooling systems. They are even used to measure food storage temperatures and can do this with no cross-contamination. 8. Are digital or infrared thermometers more accurate?Ranging from 0 to 600 Fahrenheit, the best IR Thermometer has a correct accuracy of about ±3.5 Fahrenheit. A digital thermometer could be used in three different ways. The accuracy of each might differ from one another. 9. What are the benefits of a non-contact infrared thermometer?• The non-contact approach may reduce the risk of spreading disease between people being evaluated.• Easy to use.• Easy to clean and disinfect.• Measures temperature and displays a reading rapidly.• Provides the ability to retake a temperature quickly. 10. How do I know if my digital thermometer is accurate?Add a little clean water until the glass is full and stir. Wait for about three minutes before inserting the sensor on the thermometer into the ice-filled water. Wait for about thirty seconds and check that the thermometer reads 32°F. If it does, then it is accurate, but if not, it requires calibration. 

CatalogⅠ IntroductionⅡ Types of sensors in the phone  2.1 Acceleration sensor  2.2 Gravity sensor  2.3 Light sensor  2.4 Proximity sensor  2.5 Magnetism Sensor  2.6 Gyroscope  2.7 GPS position sensor  2.8 Hall Sensor  2.9 Air pressure sensor  2.10 Heart rate sensor  2.11 Blood oxygen sensor  2.12 UV sensor  2.13 Temperature sensor  2.14 Fingerprint sensorⅢ Integrated application of sensors in the phoneⅣ SummaryⅤ FAQⅠ IntroductionThe development speed of smartphone 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.Ⅱ Types of sensors in the phone2.1 Acceleration sensorThe 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. 2.2 Gravity sensorThe gravity sensor is realized by piezoelectric effect. There are a heavy object and piezoelectricity piece integrated into 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. 2.3 Light sensorThe light sensor is similar to the eye of a mobile phone. The human eye can adjust the light entering the eye in a 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. 2.4 Proximity sensorIt 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. 2.5 Magnetism SensorThe magnetic field sensor uses 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. 2.6 GyroscopeGyroscope 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. 2.7 GPS position sensorThere 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. 2.8 Hall SensorThe 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. 2.9 Air pressure sensorWhen 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. 2.10 Heart rate sensorIrradiate 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 heartbeats 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. 2.11 Blood oxygen sensorLike heart rate sensors, hemoglobin and oxyhemoglobin in blood have different absorption ratios for the 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. 2.12 UV sensorThe 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. 2.13 Temperature sensorMany 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. 2.14 Fingerprint sensorAt 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 microcurrent 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.Ⅲ Integrated application of sensors in the phoneNowadays, the technology level of smartphones 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. ① Super safe 3D ultrasonic fingerprint recognitionThe 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 smartphones. 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. ② Iris recognition of mobile phoneThe 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. ③ RWB technology creates an intelligent and beautiful imageThe 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. ④ Leica dual cameraLeica 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 monitoringThis 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. ⑤ 3D visual sensory experience of eye-tracking technologyThe 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 a 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.Ⅳ SummaryThe 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 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. Ⅴ FAQ1. What sensors does a phone have?• Accelerometer.• Ambient Light Sensor.• Ambient Temperature Sensor.• Air Humidity Sensor.• Barometer Sensor.• Finger Print Sensor.• Gyroscope Sensor.• Harmful Radiation Sensor and so on. 2. How many sensors are there in mobile?Today's mobile devices are packed with nearly 14 sensors that produce raw data on motion, location and the environment around us. This is made possible by the use of micro-electromechanical systems (MEMS). 3. How many types the capacitive touch sensors are classified?There are two types of capacitive touch sensors: surface capacitive sensing and projected capacitive sensing. In surface capacitive sensing, an insulator is applied with a conductive coating on one side of its surface. On top of this conductive coating, a thin layer of the insulator is applied. 4. What is the proximity sensor on phone?In Android, the proximity sensor is primarily used to detect when the user's face is close to the screen. ... This is how the phone screen seems to know to switch off when you hold it up to your ear during phone calls, preventing any errant button presses. 5. Do phones have a motion sensor?Most Android-powered devices have an accelerometer, and many now include a gyroscope. The availability of software-based sensors is more variable because they often rely on one or more hardware sensors to derive their data. 6. Which sensor is used in the touchscreen?Optical touchscreens use infrared emitters combined with infrared image sensors to continuously scan the touchscreen. When an object comes into contact with the touchscreen, it blocks some of the infrared light being received by the sensors. 7. What is a simple touch sensor?The Touch Sensor is sensitive to touch, pressure as well as force. The Touch Sensor works similar to that of a simple switch. When there is contact or a touch on the surface of the Touch Sensor. It acts like a closed switch and allows the current to flow through it. 8. How do I find the sensor code on my phone?To get the ball rolling, simply open your Samsung phone app. From there, enter *#0*# using the dial pad, and the phone will immediately go into its secret diagnostic mode. Note that the process is automatic, so there's no need to tap on the green call button to enter the command. 9. How accurate are phone gyroscopes?They used an algorithm designed for repetitive, well-defined, and bounded pedaling leg movement. Their results show that the achieved accuracy of gyroscope angular tracking in pedaling is in the range of 2.2°–6.4°. Many works have been published on golf swing motion tracking. 10. What is a depth sensor in mobile?The DepthVision Camera is a Time of Flight (ToF) camera on newer Galaxy phones including Galaxy S20+ and S20 Ultra that can judge depth and distance to take your photography to new levels. ... With Quick Measure, the camera acts as a 3D camera, judging width, height, area, volume, and more when you put an object in the frame. 

Warm hints: The word in this article is about 3500 words and  reading time is about 15 minutes.   Based on the heat balance principle, the basic theory for the calculation of steady and transient temperature rise of transformer is discussed.   The calculation of transformer temperature rise is mainly used to make sure that the steady-state temperature rises produced by the transformer with rated load in long-term continuous operation will not exceed the limit specified in the standard or technical contract. In addition, the data of overload operation capacity of transformer running under various rated loads are also used to offer support to the measures taken to ensure safe overload operation of electrical systems.   However, from the author's current reading of recent info on transformer principles, design, and calculation theories available, it may be due to the limitation of space or different aspects of emphasis that they are always making an introduction to various practical formulas for transformer temperature rise calculation in a practical way. As to the involved thermal principle of calculating the transformer temperature rise is always a bit of an oversimplification I think, especially the thermal analyses demonstrating how heat energy be absorbed(or dissipate) and the temperature goes up(or goes down) during a heating process. In this article, therefore I would like to make some theoretical discussions to solve this problem and add some extra explanations needed.   Catalog   I. Brief Introduction II. Heating & Cooling Process 2.1 Heating process when the thermal power is constant 2.2 The cooling process in which the heated body is no   longer supplied with heat 2.3 Just as same as the situation of 2.1, but Τ≠0 when   t=0 III. Further Analysis of Some Formula 3.1 Mechanism of temperature-rising process of heated   body 3.2 Properties and applications of Τu in formula 2 3.3 Definition, function and derivation of the thermal   time constant Τ IV. Conclusion FAQ I. Brief Introduction   It is well known that heat is always transferred automatically from a high-temperature object to a low-temperature object. Heat can transfer (or move) in three ways: conduction, convection, and radiation, usually a combination of two or three of them may cause the transmission (also known as heat dissipation).   Before formally describing this section, I would like to quote two conclusions from laboratory research that are fundamental to thermal science:   1) the temperature rise of an object is directly proportional to the heat (heat) supplied by the outside world and inversely proportional to its own mass and Specific Heat Capacity.   2) the heat energy (calorific energy) that a heating object disperses into a cooler object(cooling medium) within a unit of time is directly proportional to the area of its radiating surface, the temperature difference, and the Heat Transfer Coefficient between the heating object and cooling medium.   Specific heat capacity: the ratio of the heat added to (or removed from) an object to the resulting temperature change per unit mass of material.   Heat transfer coefficient: when the temperature difference between the heating object and the cooling object is 1K, the heat from the unit dissipation surface area to the cooler object within a unit of time.   For the convenience of discussion, the heating object is referred to as the heated body in this paper, and the object which gets the heat released from the heated body is called the cooling body (or the cooling medium).   Take a dry transformer, for example, its winding and core are heating bodies, and the cooling body refers to the air around the transformer. For oil-immersed transformers, in addition to the winding and core known as heating bodies, the oil-filled in the transformer can also be called a heating one in relation to ambient air or cooling water. However, relative to the winding and core, oil is also called a cooling body(cooling medium).   Fig. 1 Transformers are found everywhere alternating current is used   II. Heating & Cooling Process   2.1 Heating process when the thermal power is constant Suppose that in the heating process (that is, the heat is still in a transition state, not reaches a stable state yet), the temperature rise by Τ relative to the cooling medium, the temperature rise increases dΤafter a tiny time unit dt.   The heat supplied by the outside during this dt period is a constant thermal power of Pdt(P. For windings in oil-immersed transformers, it refers to load loss; for oil, it refers to total loss). Let the heat supplied by the outside surroundings during this dt period be Pdt(P is the constant thermal power; for windings in oil-immersed transformer, P refers to load losses, and for oil, the total losses). Some of the Pdt is the heat absorbed when the temperature rise of the heated body increases by dΤ, and the other part is dispersed into the cooling medium.   In order to understand the nature of this physical phenomena in the heating process better, suppose the heated body is an isothermic one, therefore the density, specific heat capacity, and any other parameters being the same, including the heat dissipation capacity of each point on the surface.   According to the principle of thermal balance (it comes down to the law of energy conservation), the states of the heating process described above can be represented by the following equations:   Where   P——Constant value of thermal power c——Specific heat capacity of the heated body G——the mass of the heated body F——Heat dissipation surface area of the heated body k——Heat transfer coefficient  Τ——Temperature difference (or temperature rise) between the heated body and cooling body at a certain time   The first item on the right of Equation (1) indicates the heat energy absorbed by the heated body when it increases the temperature of dΤ; The second item indicates that the heat energy is dispersing to the cooling body while the heated body is storing heat.   When the temperature rise of the heating body does not go up, that is, when the temperature rise reaches a stable state, then there is dΤ=0 and Τ=Τu (Τu means the steady-state temperature rise).   At this point, from formula (1) there is:   According to the above analyses we can see: formula (1) is the mathematical expression of the heat balance principle under the transient state; formula (2) is the mathematical expression of the heat balance principle under steady-state.   From Formula (1) and Formula(2) we can get a first-order differential equation of Τ:   Where: From formula (4), the parameters on the right side of the equation are the physical parameters of the object itself, so Τ is a constant and has a dimension of time, so it is called the thermal time constant. In the physical sense, Τ is the ratio of the heat storage capacity of the heated body to the heat dissipation capacity per unit time of the heating system studied, which is an attribute of the heated body. Therefore formula (4) is considered to be the definition of Τ and the formula (4') is another expression for calculation.   To obtain the solution of formula (3) we let t=0 and Τ=0, then this is what we get:   Note that sometimes it is easier to express the formula (5) with temperature θ instead of temperature rise Τ, so it is reworded as follows: Where:   θ——The temperature of heated body at any given moment and there is θ-θа=Τ θа——The temperature of cooling body θu——The steady state temperature of the heated body that reaches a steady state Δθu——θu-θа=Τu   The rising curve in Fig. 1 shows the temperature rise of heated body changes with time t.   In order to visually see how the Τ changes with the temperature rise, Fig. 1  shows two curves with different Τ and same Τu. Fig. 2 Relation between temperature-rise(Τ)of heated body and time(t) As can be seen directly from formula (5), formula (5') and Fig. 1, the process of temperature rising of a heated body is characterized by the fact that it changes fast at the very start, then gradually slows down, and when the time t becomes equals to (4～6)Τ, it remains almost unchanged, at this point it can be assumed that Τ reaches Τu (theoretically t reaches ∞).   2.2 The cooling process in which the heated body is no longer supplied with heat   When the temperature rise of the heated reaches Τu and no heat will be emitted, the temperature rise begins to go down from Τu to zero, which we call the cooling process. At this point, its transient process equation can still be deduced by formula (1), in which you need only to let P be equal to zero.   Therefore the first-order differential equation of its temperature rise is as follows:   The solution is: All the symbols of parameter in the formula above are identical with those in formula (5), except that Τu is the initial value of temperature rise when t=0; when (4～6)Τ later, Τ≈0.   Why would we worry about Formula 6?    This is because the temperature rise of winding got at the end of the current transformer temperature rise test, is still the value of temperature rise calculated through measurements of the resistance value of the winding which will change with the temperature. The resistance value measurement is still carried out in the temperature rise test under a way of supply voltage been removed, thus the formula (6) should be used to calculate.     2.3 Just as same as the situation of 2.1, but Τ≠0 when t=0 When the heating body is supplied with constant heat power and Τ=Τ0 (≠0) when t=0 satisfied, the whole process of deduction of temperature rise calculation, with the exception of the situation of Τ=Τ0 when t = 0, is the same as 2.1, in other words, the formula of temperature rise can still be deduced from formula (5) as follows: Comparing this with the formula (5) we notice that there is a new second item occurs. Considering the physical meaning of the expression is not obvious enough, it is now rewritten (which will not change the result of the calculation) as: These two formulas above show a case that the transformer is suddenly asked to conduct a overload operation running beyond the steady load.   III. Further Analysis of Some Formula   3.1 Mechanism of temperature-rising process of heated body Formula (5) and Fig. 1 describe the rising process of heated body temperature from a mathematical point of view. This process is characterized by a rapid start and then a gradual slow down until it finally stops rising and reaches a stable temperature rise of Τu .   In this section, characteristics of heating and cooling mechanism in this process will be described from a physical point of view. So we divide the t into n small and equal time periods when t=Τu, that is Δt1=Δt2=……=Δtn=Δt (theoretically t=∞, but in practice, it is desirable to suppose that t=(4～6)T, considering the value required of Tu with a higher accuracy). Therefore, the derivative symbol "d" in this article is replaced with a increment sign "Δ".   Please note that the heat energy supplied by surroundings in each time period is equal to P·Δt (P is the constant thermal power).   Now let us take a look in the first time period Δt1. Since the temperature of heated body has already made be equal to the cooling body when t=0, that is Τ=0, according to the second item of formula (1), we can assume the heat energy emitted is also equal to 0 during the period of Δt1 until the end of present stage. Therefore, during the Δt1 period, the final increments of the temperature rise of the heated bodyΔΤ1 is determined by the total external heat energy (P·Δt). So the temperature rise at the end of first time period Δt1 is Τ1=ΔΤ.    According to the same analytical principle, we continue with the second time period Δt2. Since the initial temperature rise at the beginning of Δt2 is the that of the first time period Δt1, it can be included that Τ1=ΔΤ1. The heat emitted during Δt2 is no longer zero, but . At the end of the Δt2, the increment value of temperature rise of heated body ΔΤ2 is determined by , so there we have ΔΤ2<ΔΤ1 (That is, the increment of temperature rise in the second period is smaller than that in the first period).   Finally, at the end of the second time period Δt2, the temperature rise Τ2 is equal to ΔΤ1+ΔΤ2. The rest may be deduced by analogy, at the end of Δtn time period, the temperature rise is , also ΔΤn=0 has been illustrated at the same time.   According to the changes of temperature increment ΔΤn in each of time period above, there always are: ΔΤ1>ΔΤ2…>ΔΤn-1>ΔΤn (ΔΤn=0), therefore demonstrating the trend that all the heat absorbed by heated body in each time period gradually goes down from P·Δt absorbed in the time period of Δt1 to 0 absorbed in the time period of Δtn. The heat energy emitted in each of the corresponding time periods is gradually increased from 0 to (from the first time period Δt1 to the end of the NO.n time period Δtn). That also means the final temperature rise (steady temperature rise) is: After the temperature rise reaches the stable value of Τu, the heated body no longer absorbs external heat energy, which indicates that all the external heat energy has been dispersed to the cooling body.   3.2 Properties and applications of Τu in formula 2 Formula 2 is a theoretical formula derived from the heat balance principle for calculating the steady-state temperature rise of the heated body. It is difficult to calculate the temperature rise directly for complex heated bodies such as transformers.   Therefore, various manufacturers and scientific research institutions have respectively obtained many practical formulas, according to their own practical experience or scientific research results and the characteristics of the heated body structure and three different heat dissipation forms, including conduction, convection, and radiation.   Furthermore, a heated body such as a transformer having a complex structure does not always have the characteristics of the homogeneous isothermal body assumed in formula 2, and the heat-dissipation capability at each point on the surface is not equal, either.   Therefore, the steady-state temperature rise (Τu) calculated from formula 2 (including the relevant practical formula based on formula 2) on the whole indicates the average value of temperature rise at different points in the heat source.   The calculation of the maximum temperature rise (temperature) of an object at a "hot spot" of concern has so far could only be mainly estimated by experience and the use of temperature rise measurements in certain heaT tests (for example, confirming the difference between the maximum temperature rise and the average value or confirming the multiple values between them to estimate).   3.3 Definition, function and derivation of the thermal time constant Τ Formula 4 is the definition expression of thermal time constant. It is obtained in the derivation of formula 5 from formula 2 and formula 1. Therefore, it is possible to think that equation 4 is obtained under the admission that when t=∞ it has dΤ=0 and Τ=Τu, the latter of which is obtained under the boundary conditions of objective reality. Because the definition of "Τ" and some functions have been described in section 2.1, here i only do some additional analyses to formula 7 which shows applications of transformer temperature rise under a short-time overload operation. Fig. 3 What is a Transformer   The basic theory of transformer and working principle of transformer   Fig. 4 Large power transformers have their core and windings submerged in an oil bath to transfer heat and muffle noise, and also to displace moisture which would otherwise compromise the integrity of the winding insulation. Heat-dissipating "radiator" tubes on the outside of the transformer case provide a convective oil flow path to transfer heat from the transformer's core to ambient air.   First of all, according to the statistics of a large number of dry and oil-immersed power transformers with different capacities, which have been manufactured at home and abroad, the value of Τ is generally not less than 1h (for oil-immersed transformer, although the T of winding is quite low, about 5 min-20 mins, the T of oil is 1h～5h.    Noting that the oil actual temperature rise is generally not lower than the temperature difference between the winding and the oil and that the thermal time constant of the oil should therefore be considered to control the temperature rise of the winding during the overload operation, that is, the temperature difference between winding and ambient air or temperature of cooling water still plays a decisive role.    Although the Τu of the transformer will obviously exceed the temperature rise limit of rated-load operation, as long as the time t has been controlled within T, it can still make the actual temperature rise running in short-time overload not excess the temperature rise limit of short-time overload operation. These permissible limits, according to the standard of the load guide of the oil-immersed power transformer, is related to the operation type within nameplate capacity, namely, normal periodicity, long-term or short-term emergency, and generally higher than that of rated temperature rise.   It can be seen from this that the function of the thermal time constant T is relatively large, so it is necessary to pay close attention to its definition, various affecting factors, and derivation of its formula. However, I have seen some people added another boundary condition except dΤ=0 during the derivation of the expression of Τ: in extreme cases, the heat will not be transferred into the surrounding medium at all, which is also called "adiabatic condition". In this regard, I would like to put forward the following different views for discussion.   (1) In this article, the derivations of formula 4 and formula 5 have only used a "boundary condition" of dΤ=0 (Τ=Τu) when t=∞, so there is no need to add another adiabatic condition for derivation.   It is said that without heat dissipation, the time required to reach a stable temperature is called time constant (Τ), but that will only be true when the second item (dissipated heat) on the right of the equation meets a condition of , now that to reach a steady temperature Τ must be equal to Τu, which is at variance with objective reality of electric accessories including transformers.   Some might say that when people calculate the temperature of a transformer at a short-circuit current, don't they also use the formula obtained under the "adiabatic condition" to calculate the temperature of the transformer? Yes, but the case being considered is only the "short time" one, that is, the formula only applies when short-circuit durations never exceed 10s (actually 2s).    The time is very small compared with the thermal time constant of winding in oil-immersed power transformer (about 5min-20mins) and that of oil (about 1lh～5h). This is still true when compared with the thermal time constant of the windings of dry-type transformers (about or above 30min). In section 3.1 of this article, such a short duration makes it is possible to consider it as an adiabatic transient system. In a broad sense, if the heat energy emitted accounts for only a very small part of the heat supplied by the outside world during a same period, it can be roughly regarded as adiabatic process. At this point, it is precisely because of the recognition of  that it is in line with objective reality.   This proves that adiabatic conditions should not be used as the basis in the derivation of expression of Τ (formula 4) and that of transient temperature rise (formula 5).   (3) From the details of the derivation process in this article, I would like to say that the true expression of temperature rise of the heated body still has not been obtained yet in the end. Think about that, a task for you, my readers.   IV. Conclusion   (1) Starting from the principle of heat balance, this article expounds the model of the heating mechanism in the rising process of temperature rise of the heated body with concise mathematics and physical language.   (2) It is clearly pointed out in this paper that the steady temperature rise of the heated body can be calculated by using formula 2, and formula 5 and formula 7 are the formulas for calculating the temperature rise of the heated body during the transient process.   (3) It is pointed out that to obtain the expression of the transient temperature rise of the thermal time constant Τ and the heated body, the adiabatic condition should not be used for the process of derivation, which is not necessary either.   (4) Due to space constraints, this article has not covered the heat dissipation mechanism of heated body, but you readers can refer to other references about heat loss or transfer in Kynix and other sites.   FAQ   1. How hot is too hot for a power transformer? Transformers designed with high-temperature insulation systems can run safely at temps up to 200°F. But remember, a hot-running transformer is an angry transformer.    2. What is ambient temperature of transformer? The average ambient temperature for a transformer over a 24 hour period should not exceed 30 degrees Celsius. For instance, if the transformer ambient temperature was 40 deg. C for 12 hours, then the transformer must not exceed 20 deg.   3. Should doorbell transformer be hot? Transformers are always going to produce some heat. It's a part of the step-down process. It should only be warm to the touch, however.   4. What is maximum ambient temperature? In general, a safe range is between 60 and 75 degrees Fahrenheit or 15 and 25 degrees Celsius, although the cooler end of that range is better. Ambient temperatures above those ranges make it difficult for a computer's cooling system to keep it at a safe operating temperature.   5. What is the name of oil used in transformer? Mineral oil and Synthetic oil are the majorly used transformer oil. These are the petroleum products, like Naphthenic based transformer oil and Paraffinic based transformer oil. Naphthenic based transformer oils are known for their heat distribution, which is one of the main problems with transformer.   6. What will happen if the regulation of a transformer is poor? If the transformer supplies a very low lagging power factor, large secondary currents will flow resulting in poor voltage regulation due to greater voltage drops in the winding. ... Therefore positive regulation produces a voltage drop in the winding while a negative regulation produces a voltage rise in the winding.   7. What is high transformer temperature? Standard Ratings and Overload Capacity：Dry-type transformers are available in three standard temperature rises: 80C, 115C, or 150C. Liquid-filled transformers come in standard rises of 55C and 65C. These values are based on a maximum ambient temperature of 40C.   8. What is hot spot temperature in transformer? Modern transformers make use of thermally upgraded paper that has been chemically treated to improve the stability of cellulose structure. The rated hot spot temperature for this kind of paper is 110°C and it can be seen that an increase of 7°C will double the aging acceleration factor.   9. How much heat does a 75 kVA transformer give off? According to Cutler-Hammer, a 75-kVA, 150°F-rise, dry-type transformer has an efficiency of 97.2% at 1/4 load and 96.7% at full load. So, figure 3% loss at 75 kVA, which would represent 2,250 W.   10.What happens when transformer is overloaded? The weakening of the system will happen faster if the transformer is frequently overloaded. The net result of small, incremental increases in loading capacity over time is a weakened insulation system. Overloading causes overheating, and eventually thermal degradation that acts thrrough cracks in the insulation.   You May Also Like: Some suggestions about protecting transformers Learn Some Basic Knowledge about Capacitor Voltage Transformer  

SummaryA digital temperature sensor IC which offers accurate measurements in the temperature range -20 to 10°C has been introduced by ams. The performance of the AS6200C makes it easier for designers of refrigerators and data loggers in cold-chain storage equipment to meet demanding targets for system-level accuracy. The AS6200C’s measurements are accurate to ±0.2°C between -20°C and 10°C, the temperature range over which storage equipment for perishable goods operates.  AS6200C Sensor ICAS6200C sensor's accuracy is guaranteed over the device's supply voltage range of 1.8~3.6V. In temperature control and temperature logging applications, the total error budget is made up of multiple components. By minimising the error at the point of measurement, the designer gains extra headroom for other error and noise sources, such as the heat generated by board-mounted com-ponents. The use of the highly accurate AS6200C gives the designer more flexibility to modify other elements of the system design while keeping total error below a specified maximum level. The AS6200C integrates a sensor front end, 12-bit analogue-to-digital converter and digital logic in a small WL-CSP package. It provides a digital output over an I2C interface to any host microcontrol-ler. The device performs on-board digital signal processing, which means that it needs no user calibration, and its linearised output requires no compensation by an external microcontroller. The AS6200C is intended for use in equipment for storing and transporting food, pharmaceuticals, flowers and other perishable goods, as well as in domestic and commercial refrigerators. It is well suited to data loggers that comply with the EN12830:1999 class 1 standard.The new device extends the ams family of small, accurate digital temperature sensor ICs, joining the AS6200 sensor, which achieves peak accuracy between 0 and 65°C. “The AS6200C offers the market a unique combination of small size - its footprint is only 1.5mm2 - very high accuracy over the cold-chain monitoring and storage temperature range, and a convenient digital output requiring no calibration or linearisation. It provides a new example of the value of the low noise, high sensitivity, high linearity semiconductor technology underlying the outstanding performance of ams' sensor solution products,” said Nikolai Haslebner, Marketing Manager at ams. 

“For the living room, a sensual green with temperature and motion sensors.” In the future, you may be able to order that or something similar for your smart home. Sometime soon, new types of sensors could become a reality on your four walls.Science or fiction? More and more often, we find ourselves having to answer that question with science. That also applies to tiny new sensors that—hidden in wall paint—could make smart homes even smarter. On the one hand, they would have to be very, very small, and on the other, they would have to work without a battery. Researchers at the University of Eindhoven have already found an elegant solution. Their tiny temperature sensor gets its energy from the same radio waves that it uses to transmit its measuring results. First it receives radio waves from a special router via an antenna and stores it as energy. Starting at a certain energy level, it then measures the temperature and sends the results to the router. And it does so at exactly the same frequency that was chosen in advance for the measured temperature value. The router then uses the information to calculate the actual temperature. The walls have earsThe range of the tiny sensor, which measures just two square millimeters in size and weighs just 1.6 milligrams, is limited to 2.5 centimeters. But researchers hope to reach one meter during the next year. They are aiming for up to five meters in the future. Because the sensor also works under a coat of paint, pavement or concrete, there are only a few restrictions to its applications. For example, in smart homes or production environments, it could be “painted” onto the building’s walls with paint. And not just as a “thermometer”. The technology can also be used for sensors that measure motion, light and moisture. Right now the sensor stems from a 65-nm CMOS process. Produced in mass, the cost of production should come in at around 30 cents. Ref.KY45-LM35DTKY45-AMB2402

Electrical engineers at the University of California San Diego have developed a temperature sensor that runs on only 113 picowatts of power -- 628 times lower power than the state of the art and about 10 billion times smaller than a watt. This near-zero-power temperature sensor could extend the battery life of wearable or implantable devices that monitor body temperature, smart home monitoring systems, Internet of Things devices and environmental monitoring systems.   The technology could also enable a new class of devices that can be powered by harvesting energy from low-power sources, such as the body or the surrounding environment, researchers said. The work was published in Scientific Reports on June 30.   "Our vision is to make wearable devices that are so unobtrusive, so invisible that users are virtually unaware that they're wearing their wearables, making them 'unawearables.' Our new near-zero-power technology could one day eliminate the need to ever change or recharge a battery," said Patrick Mercier, an electrical engineering professor at UC San Diego Jacobs School of Engineering and the study's senior author.   "We're building systems that have such low power requirements that they could potentially run for years on just a tiny battery," said Hui Wang, an electrical engineering Ph.D. student in Mercier's lab and the first author of the study.   Building ultra-low power, miniaturized electronic devices is the theme of Mercier's Energy-Efficient Microsystems lab at UC San Diego. Mercier also serves as co-director for the Center for Wearable Sensors at UC San Diego. A big part of his group's work focuses on boosting energy efficiencies of individual parts of an integrated circuit in order to reduce the power requirement of the system as a whole.   One example is the temperature sensor found in healthcare devices or smart thermostats. While the power requirement of state-of-the-art temperature sensors has been reduced to as low as tens of nanowatts, the one developed by Mercier's group runs on just 113 picowatts -- 628 times lower power.   Minimizing power   Their new approach involves minimizing power in two domains: the current source and the conversion of temperature to a digital readout.   Researchers built an ultra-low power current source using what are called "gate leakage" transistors -- transistors in which tiny levels of current leak through the electronic barrier, or the gate. Transistors typically have a gate that can turn on and off the flow of electrons. But as the size of modern transistors continues to shrink, the gate material becomes so thin that it can no longer block electrons from leaking through -- a phenomenon known as the quantum tunneling effect.   Gate leakage is considered problematic in systems such as microprocessors or precision analog circuits. Here, researchers are taking advantage of it -- they're using these minuscule levels of electron flow to power the circuit.   "Many researchers are trying to get rid of leakage current, but we are exploiting it to build an ultra-low power current source," Hui said.   Using these current sources, researchers developed a less power-hungry way to digitize temperature. This process normally requires passing current through a resistor -- its resistance changes with temperature -- then measuring the resulting voltage, and then converting that voltage to its corresponding temperature using a high power analog to digital converter.   Instead of this conventional process, researchers developed an innovative system to digitize temperature directly and save power. Their system consists of two ultra-low power current sources: one that charges a capacitor in a fixed amount of time regardless of temperature, and one that charges at a rate that varies with temperature -- slower at lower temperatures, faster at higher temperatures.   As the temperature changes, the system adapts so that the temperature-dependent current source charges in the same amount of time as the fixed current source. A built-in digital feedback loop equalizes the charging times by reconnecting the temperature-dependent current source to a capacitor of a different size -- the size of this capacitor is directly proportional to the actual temperature. For example, when the temperature falls, the temperature-dependent current source will charge slower, and the feedback loop compensates by switching to a smaller capacitor, which dictates a particular digital readout.   The temperature sensor is integrated into a small chip measuring 0.15 × 0.15 square millimeters in area. It operates at temperatures ranging from minus 20 C to 40 C. Its performance is fairly comparable to that of the state of the art even at near-zero-power, researchers said. One tradeoff is that the sensor has a response time of approximately one temperature update per second, which is slightly slower than existing temperature sensors. However, this response time is sufficient for devices that operate in the human body, homes and other environments where temperature do not fluctuate rapidly, researchers said.   Moving forward, the team is working to improve the accuracy of the temperature sensor. The team is also optimizing the design so that it can be successfully integrated into commercial devices.     Ref. ADT7410TRZ-REEL DS18B20