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What is a sensor?

Surely you have heard the word “sensor” more than once. It is obvious that this word means some technical device. What is a sensor and how does it work? What types of sensors are there? Let's consider all these questions in more detail.

The concept of a sensor

Currently, it is common to call a sensor an element that converts information received from the medium into an electrical signal in order to further transfer information to some other device. Typically, the sensor is a structurally separate part of the measuring system.

Sensors are used everywhere: in cars, heating systems, water supply, in production, in medicine, even in catering establishments to measure temperature in order to determine the degree of readiness of a dish.

Sensor classification

There are several types of sensor classification. We present the most basic ones.

By type of measurement:

Pressure Sensors;
Flow sensors;
Level measurement sensors;
Temperature measurement sensors;
Concentration sensors;
Radioactivity sensors;
Movement sensors;
Angular position sensors;
Sensors for measuring mechanical quantities;
Vibration sensors.

Classification by manufacturing technology:

Elemental sensors;
The sensors are integral.

Classification according to the principle of action:

This includes:

Optical sensors that use electromagnetic radiation and react to water vapour, smoke and different kinds aerosols. They are non-contact sensors. The principle of their work is based on capturing by a sensitive sensor the impact of any irritant, for example, water vapor. These sensors are widely used in automated systems management.
inductive sensors. They belong to non-contact sensors, designed to calculate the position of an object. Inductive sensors perfectly capture the fluctuations of the electromagnetic field. Their design is based on a generator, which creates an electromagnetic field, the impact of which on a metal object generates oscillation amplitudes, to which the sensor reacts. Such sensors are widely used in metal detectors, as well as in various kinds of electronic locks.
capacitive sensors. It is these sensors that are used in cars as rain sensors, touch buttons household appliances, fluid measurement sensors. The principle of their action is to respond to the action of the liquid. The insulator of such sensors has a dielectric constant. The liquid, acting on the insulator, causes the appearance of an electrical signal, which is converted into information. Such sensors are widely used in household appliances.
Load cells. Load cells are a device for measuring force, pressure, torque, acceleration or displacement. The mechanism of their action is based on the principle of elastic force. Such sensors are widely used in various types of scales. They convert the amount of deformation into an electrical signal, in other words, the sensor detects the impact of some force on it, after which the elastic element is deformed and the resistance of the strain gauge, which is built into such a sensor, changes. Next, the information is converted into an electrical signal and transferred to another device, such as a display.
Piezoelectric sensors. Such sensors are widely used in microphones and sonars. Their principle of operation is based on the polarization of the dielectric under the influence of mechanical stresses. In other words, piezoelectric sensors pick up a change in the electric field that has been mechanically affected. For example, in a microphone, this is the effect of voice. The result of the deformation will be the conversion of the received signal into an electrical one and its transmission to another device. These sensors were born thanks to Jacques and Pierre Curie in 1880.
Magnetic-electric sensors. These are sensors whose operating principle is based on the so-called Hall effect. These sensors are used in smartphones as the basis for the operation of an electronic compass, in electric motors, and in current meters.
Nano sensors. Are under development. The most demanded sphere for them should be medicine and robotics. It is assumed that these sensors will become a new class and will find widespread use in the future. Their principle of operation will be similar to many other sensors (hence the names nano-piezo sensors, nano-strain sensors, etc.), but their dimensions will be many times smaller

To learn more about sensors, read these articles.

- these are sensors that work without physical and mechanical contact. They work through an electric and magnetic field, and optical sensors are also widely used. In this article, we will analyze all three types of sensors: optical, capacitive and inductive, and at the end we will do an experiment with an inductive sensor. By the way, the people also call contactless sensors proximity switches, so don't be afraid if you see such a name ;-).

optical sensor

So, a few words about optical sensors ... The principle of operation of optical sensors is shown in the figure below

barrier

Do you remember any shots from films where the main characters had to go through optical beams and not hit any of them? If the beam was touched by any part of the body, an alarm was triggered.

The beam is emitted by some source. And there is also a “beam receiver”, that is, the thing that receives the beam. As soon as there is no beam on the beam receiver, the contact will immediately turn on or off in it, which will directly control the alarm or something else at your discretion. Basically, a beam source and a receiver, properly called a "photodetector", come in pairs.

SKB IS optical motion sensors are very popular in Russia.

These types of sensors have both a light source and a photodetector. They are located right in the body of these sensors. Each type of sensor is a complete design and is used in a number of machines where increased processing accuracy is needed, up to 1 micrometer. Basically, these are machines with a system H logical P software At board ( CNC) that work according to the program and require minimal human intervention. These non-contact sensors are built on this principle

These types of sensors are denoted by the letter “T” and are called barrier. As soon as the optical beam was interrupted, the sensor worked.

Pros:

range can reach up to 150 meters
high reliability and noise immunity

Minuses:

at large sensing distances, fine adjustment of the photodetector to the optical beam is required.

Reflex

The reflective type of sensors is indicated by the letter R. In these types of sensors, the emitter and receiver are located in the same housing.

The principle of operation can be seen in the figure below.

Light from the emitter is reflected from some reflector (reflector) and enters the receiver. As soon as the beam is interrupted by any object, the sensor is triggered. This sensor is very convenient on conveyor lines when counting products.

diffusion

And the last type of optical sensors - diffusion - denoted by the letter D. They may look different:

The principle of operation is the same as that of the reflex, but here the light is already reflected from objects. Such sensors are designed for a small sensing distance and are unpretentious in their work.

Capacitive and inductive sensors

Optics are optics, but inductive and capacitive sensors are considered the most unpretentious in their work and very reliable. This is how they look like

They are very similar to each other. The principle of their operation is associated with a change in the magnetic and electric fields. Inductive sensors are triggered when any metal is brought to them. They do not “peck” on other materials. Capacitive ones work on almost any substance.

How an inductive sensor works

As they say, it's better to see once than hear a hundred times, so let's do a little experiment with inductive sensor.

So, our guest is a Russian-made inductive sensor

We read what is written on it

WBI sensor brand blah blah blah blah, S - sensing distance, here it is 2 mm, U1 - version for a temperate climate, IP - 67 - protection level(in short, the level of protection here is very steep), U b - voltage at which the sensor operates, here the voltage can be in the range from 10 to 30 volts, I load - load current, this sensor can deliver up to 200 milliamps of current to the load, I think this is decent.

On the reverse of the tag is a wiring diagram for this sensor.

Well, let's evaluate the work of the sensor? To do this, we cling to the load. The load we will have is an LED connected in series with a resistor with a nominal value of 1 kOhm. Why do we need a resistor? The LED at the moment of inclusion begins to frantically eat current and burns out. To prevent this, a resistor is placed in series with the LED.

On the brown wire of the sensor we supply a plus from the Power supply, and on the blue wire - a minus. The voltage I took was 15 volts.

The moment of truth is coming ... We bring a metal object to the working area of the sensor, and the sensor immediately works, as the LED built into the sensor tells us, as well as our experimental LED.

The sensor does not respond to materials other than metals. A jar of rosin means nothing to him :-).

Instead of an LED, a logic circuit input can be used, that is, the sensor, when triggered, outputs a logic one signal that can be used in digital devices.

Conclusion

In the world of electronics, these three types of sensors are in increasing use. Every year the production of these sensors is growing and growing. They are used in absolutely different areas of industry. Automation and robotics would not be possible without these sensors. In this article, I have analyzed only the simplest sensors that give us only an “on-off” signal or, to put it in professional language, one bit of information. More sophisticated types of sensors can provide different parameters and can even connect directly to computers and other devices.

Buy inductive sensor

In our radio store, inductive sensors cost 5 times more than if they were ordered from China from Aliexpress.

Here You can look at a variety of inductive sensors.

Electronic sensors (meters) are an important component in the automation of any technological processes and in the management of various machines and mechanisms.

With the help of electronic devices, you can get complete information about the parameters of the controlled equipment.

The principle of operation of any electronic sensor is based on the conversion of controlled indicators into a signal that is transmitted for further processing by the control device. It is possible to measure any quantities - temperature, pressure, electrical voltage and current strength, light intensity and other indicators.

The popularity of electronic meters is due to a number of design features, in particular, it is possible:

transmit the measured parameters to almost any distance;
convert indicators into a digital code to achieve high sensitivity and speed;
transfer data at the highest possible speed.

According to the principle of operation, electronic sensors are divided into several categories depending on the principle of operation. Some of the most sought after are:

capacitive;
inductive;
optical.

Each of the options has certain advantages that determine the optimal scope of its application. The principle of operation of any type of meter may vary depending on the design and the monitoring equipment used.

CAPACITIVE SENSORS

The principle of operation of an electronic capacitive sensor is based on a change in the capacitance of a flat or cylindrical capacitor, depending on the movement of one of the plates. Also taken into account is such an indicator as the dielectric constant of the medium between the plates. One of the advantages of such devices is simple design, which allows you to achieve good indicators of strength and reliability.

Also, meters of this type are not subject to distortion of indicators during temperature changes. The only condition for accurate performance is protection from dust, moisture and corrosion.

Capacitive sensors are widely used in a wide variety of industries. Easy-to-manufacture devices are characterized by low production cost, while they have a long service life and high sensitivity.

Depending on the design, the devices are divided into single-capacity and spirit-capacitive. The second option is more complicated to manufacture, but it is characterized by increased measurement accuracy.

Application area.

Most often, capacitive sensors are used to measure linear and angular displacements, and the design of the device may vary depending on the measurement method (the area of the electrodes or the gap between them changes). To measure angular displacements, sensors with a variable area of capacitor plates are used.

Capacitive transducers are also used to measure pressure. The design provides for the presence of one electrode with a diaphragm, which bends under the action of pressure, changing the capacitance of the capacitor, which is fixed by the measuring circuit.

Thus, capacitive meters can be used in any control and regulation systems. In energy, mechanical engineering, and construction, linear and angular displacement sensors are usually used. Capacitive level transmitters are most effective when handling bulk materials and liquids, and are often used in the chemical and food industries.

Electronic capacitive sensors are used to accurately measure air humidity, dielectric thickness, various deformations, linear and angular accelerations, ensuring accuracy in a variety of conditions.

INDUCTIVE SENSORS

Non-contact inductive sensors work on the principle of changing the inductance of a core coil. Key feature of the meters of this type- they react only to a change in the location of metal objects. The metal has a direct effect on the electromagnetic field of the coil, which leads to the triggering of the sensor.

Thus, using an inductive sensor, you can effectively track the position of metal objects in space. This allows the use of inductive meters in any industry where monitoring of the position of various structural elements is required.

One of the interesting features of the sensor is that the electromagnetic field varies in different ways, depending on the type of metal, which somewhat expands the scope of the devices.

Inductive sensors have a number of advantages, of which the absence of moving parts deserves special attention, which significantly increases the reliability and strength of the structure. Also, sensors can be connected to industrial voltage sources, and the principle of operation of the meter guarantees high sensitivity.

Inductive sensors are made in several form factors, for the most convenient installation and operation, for example, dual meters (two coils in one housing).

Application area.

The scope of use of inductive meters is automation in any industry. A simple example - the device can be used as an alternative to a limit switch, while the response speed will be increased. Sensors are made in a dust and moisture protective housing for operation in the most difficult conditions.

Devices can be used to measure a wide variety of quantities - for this, converters of the measured indicator into the displacement value are used, which is fixed by the device.

OPTICAL SENSORS

Non-contact electronic optical sensors are one of the most popular types of meters in industries that require efficient positioning of any objects with maximum accuracy.

The principle of operation of this type of meters is based on fixing the change in the luminous flux when an object passes through it. The most simple circuit devices are an emitter (LED) and a photodetector that converts light radiation into an electrical signal.

In modern optical meters, a modern electronic coding system is used, which makes it possible to exclude the influence of extraneous light sources (protection against false positives).

Structurally, optical meters can be performed both in separate housings for the emitter and receiver, or in one, depending on the principle of operation of the device and its field of application. The housing additionally provides protection against dust and moisture (for operation under low temperatures use special heat shields).

Optical sensors are classified depending on the scheme of operation. The most common type is barrier, consisting of an emitter and a receiver located strictly opposite each other. When the constant light output is interrupted by an object, the device gives a corresponding signal.

The second popular type is a diffuse optical meter, in which the emitter and photodetector are located in the same housing. The principle of operation is based on the reflection of the beam from the object. The reflected light flux is captured by a photodetector, after which the electronics are triggered.

The third option is a reflective optical sensor. As in a diffuse meter, the emitter and receiver are structurally made in the same housing, but the light flux is reflected from a special reflector.

Usage.

Optical sensors are widely used in automated control systems and serve to detect objects and count them. The relatively simple design ensures reliability and high measurement accuracy. The coded light signal provides protection against external factors, and electronics allows you to determine not only the presence of objects, but also determine their properties (dimensions, transparency, etc.).

Optical devices are widely used in security systems, where they are used as effective motion sensors. Regardless of the type, electronic sensors are the best way for modern systems control and automatic equipment.

The high accuracy and speed of measurement ensure the proper functioning of the equipment with minimal deviations. At the same time, most electronic meters are non-contact, which increases the reliability of devices several times and guarantees a long service life even in difficult production conditions.

The materials presented on the site are for informational purposes only and cannot be used as guidelines and normative documents.

A modern car is made up of many mechanical, electromechanical and electronic components. Optimum performance engine must be provided regardless of external conditions. When external factors change, the operation of nodes and components must adapt to them. Vehicle sensors serve as a kind of tracking device for the operation of the car. Consider the main sensors:

3. Air flow sensor in a car - what does it affect?

The principle of operation of the air flow sensor is based on measuring the amount of heat given off to the air flow in the engine intake manifold. Heating
the sensor element is installed in front of the vehicle's air filter. Change
air flow rate and, accordingly, its mass fraction, is reflected in the degree
changes in the temperature of the heating coil of the MAF sensor.

"Tripling" of the engine during operation and loss of power indicates a possible failure of the air flow sensor.

4. Oxygen sensor, lambda probe - sensor malfunction

An oxygen sensor or lambda probe detects the amount of oxygen left in the exhaust manifold after fuel combustion. The lambda probe is part of the electronic engine management system, which regulates the amount of fuel, ensuring its complete combustion. Increased fuel consumption characterizes possible malfunction sensor.

5. Throttle sensor - symptoms of malfunction

This sensor is an electromechanical device consisting of a sensing element and a stepper motor.

The sensitive element is
temperature sensor, and the stepper motor is the actuator.
This electromechanical device changes the position of the throttle valve
relative to the coolant temperature. Thus, the rotation frequency
crankshaft of the engine depends on the degree of heating of the coolant.

A characteristic symptom of a malfunction of this sensor is the lack of warm-up speed and increased fuel consumption.

6. Oil pressure sensor - functions, failure

On cars of the Japanese brand, a diaphragm oil pressure sensor is installed
type. The sensor consists of two cavities separated by a flexible membrane. Butter
acts on the membrane on one side, bending from pressure. In the measuring
The membrane of the sensor cavity is connected to the rheostat rod.

Depending on the engine oil pressure, the diaphragm flexes more or less, changing the overall resistance of the sensor. The oil pressure sensor is located on the engine block.

A burning oil pressure light on the car panel may indicate a sensor failure.

7. Is the knock sensor in the engine not working?

The engine knock sensor measures the ignition timing. During normal engine operation, the sensor is in "idle" mode. When the process changes
combustion in the direction of the explosive nature of the combustion of fuel-detonation, the sensor sends a signal to the electronic engine control system to change the advance angle
ignition in the direction of decreasing.

It is located in the area air filter on the cylinder block. To check the performance of the knock sensor, you must run.

8. Camshaft angle sensor - troit engine

This sensor is located on the cylinder head and measures the engine speed.
camshaft of the engine, and based on the signals from the sensor, the control unit determines the current position of the pistons in the cylinders.

Uneven engine operation and tripling indicate incorrect operation of the sensor. The check is carried out using an ohmmeter, measuring the resistance between the sensor terminals.

9. ABS / ABS sensor in the car - check the performance

Electromagnetic type ABS sensors are installed on the wheels of the car and are part of the car's anti-lock braking system.

Sensor function is the measurement of wheel speed. The object of measurement of the sensor is the signal gear disk, which is mounted on the wheel hub. If the ABS sensor is faulty, the control light on the control panel does not go out after starting the engine.

The technology for determining the operability of the sensor is to measure the resistance between the contacts of the sensor, in case of a malfunction, the resistance is zero.

10. Fuel level sensor in a car - how to check if it works?

The fuel level sensor is installed in the fuel pump housing and consists of several components. The float, through a long rod, acts on a sector rheostat, which changes the resistance of the sensor depending on the fuel level in the car's tank. The sensor signals are sent to a pointer or electronic pointer on the vehicle control panel. Checking the performance of the fuel level sensor is carried out with an ohmmeter, which measures the resistance between the sensor contacts.

Sensors are complex devices that are often used to detect and respond to electrical or optical signals. The device converts a physical parameter (temperature, blood pressure, humidity, speed) into a signal that can be measured by the device.

The classification of sensors in this case can be different. There are several basic parameters for the distribution of measuring devices, which will be discussed further. Basically, this separation is due to the action of various forces.

This is easy to explain with the example of temperature measurement. Mercury in a glass thermometer expands and compresses the liquid to convert the measured temperature, which can be read by an observer from a calibrated glass tube.

Criterias of choice

There are certain features that need to be taken into account when classifying a sensor. They are listed below:

Accuracy.
Environmental conditions - usually sensors have limitations in temperature, humidity.
Range - sensor measurement limit.
Calibration - essential for most measuring instruments, as readings change over time.
Price.
Repeatability - Variable readings are measured repeatedly in the same environment.

Category distribution

Sensor classifications fall into the following categories:

The primary input number of arguments.
Principles of transduction (use of physical and chemical effects).
Material and technology.
Appointment.

The principle of transduction is a fundamental criterion followed for effective information gathering. Typically, logistical criteria are selected by the development team.

The classification of sensors based on properties is distributed as follows:

Temperature: thermistors, thermocouples, resistance thermometers, microcircuits.
Pressure: Fiber Optic, Vacuum, Liquid Based Flexible Gauges, LVDT, Electronic.
Flow: electromagnetic, differential pressure, positional displacement, thermal mass.
Level sensors: differential pressure, ultrasonic radio frequency, radar, thermal displacement.
Proximity and displacement: LVDT, photovoltaic, capacitive, magnetic, ultrasonic.
Biosensors: resonant mirror, electrochemical, surface plasmon resonance, light-addressable potentiometric.
Image: Charge Coupled Devices, CMOS.
Gas and chemistry: semiconductor, infrared, conduction, electrochemical.
Acceleration: gyroscopes, accelerometers.
Others: humidity sensor, speed sensor, mass, tilt sensor, force, viscosity.

This is a large group consisting of subsections. It is noteworthy that with the discovery of new technologies, the sections are constantly updated.

Purpose of sensor classification based on direction of use:

Control, measurement and automation of the production process.
Non-industrial use: aviation, medical devices, automobiles, consumer electronics.

Sensors can be classified according to their power requirements:

Active sensor - devices that require power. For example, LiDAR (light detection and rangefinder), a photoconductive cell.
Passive sensor - sensors that do not require power. For example, radiometers, film photography.

These two sections include all devices known to science.

In current applications, the purpose of sensor classification can be grouped as follows:

Accelerometers - based on microelectromechanical sensor technology. They are used to monitor patients who turn on pacemakers. and dynamic systems of the vehicle.
Biosensors - based on electrochemical technology. Used to test food, medical devices, water and detect dangerous biological pathogens.
Image sensors - based on CMOS technology. They are used in consumer electronics, biometrics, traffic and security surveillance, and computer imaging.
Motion detectors - based on infrared, ultrasonic and microwave/radar technologies. Used in video games and simulations, light activation and security detection.

Sensor types

There is also a core group. It is divided into six main areas:

Temperature.
Infrared radiation.
Ultraviolet.
Sensor.
Approach, movement.
Ultrasound.

Each group may include subsections, if the technology is even partially used as part of a particular device.

1. Temperature sensors

This is one of the main groups. The classification of temperature sensors unites all devices that have the ability to evaluate parameters based on the heating or cooling of a particular type of substance or material.

This device collects temperature information from a source and converts it into a form that other equipment or people can understand. The best illustration of a temperature sensor is mercury in a glass thermometer. Mercury in glass expands and contracts with changes in temperature. The outdoor temperature is the starting element for measuring the indicator. The position of the mercury is observed by the viewer to measure the parameter. There are two main types of temperature sensors:

contact sensors. This type of device requires direct physical contact with the object or carrier. They control the temperature of solids, liquids and gases over a wide temperature range.
Contactless sensors. This type of sensor does not require any physical contact with the measured object or medium. They control the non-reflective solids and liquids, but useless for gases due to their natural transparency. These instruments use Planck's law to measure temperature. This law concerns the heat emitted by the source to measure the benchmark.

Working with various devices

The principle of operation and classification of temperature sensors are also divided into the use of technology in other types of equipment. These can be dashboards in a car and special production units in an industrial shop.

Thermocouple - modules are made of two wires (each - from different homogeneous alloys or metals), which form a measuring transition by connecting at one end. This measuring unit is open to the studied elements. The other end of the wire ends with a measuring device where a reference junction is formed. Current flows through the circuit because the temperatures of the two junctions are different. The resulting millivolt voltage is measured to determine the temperature at the junction.
Resistance temperature detectors (RTDs) are types of thermistors that are made to measure electrical resistance as temperature changes. They are more expensive than any other temperature detection devices.
Thermistors. They are another type of thermal resistor in which a large change in resistance is proportional to a small change in temperature.

2. IR sensor

This device emits or detects infrared radiation to determine the specific phase in the environment. As a rule, thermal radiation is emitted by all objects in the infrared spectrum. This sensor detects a type of source that is not visible to the human eye.

The basic idea is to use infrared LEDs to transmit light waves to an object. Another IR diode of the same type should be used to detect the reflected wave from the object.

Operating principle

Classification of sensors in the automation system in this direction is common. This is due to the fact that the technology makes it possible to use additional tools for assessing external parameters. When an infrared receiver is exposed to infrared light, a voltage difference develops across the wires. The electrical properties of the IR sensor components can be used to measure the distance to an object. When an infrared receiver is exposed to light, a potential difference develops across the wires.

Where applied:

Thermography: according to the law of the radiation of objects, it is possible to observe environment with or without visible illumination using this technology.
Heating: infrared light can be used for cooking and reheating food products. They can remove ice from aircraft wings. The converters are popular in the industrial field such as printing, plastic molding and polymer welding.
Spectroscopy: This technique is used to identify molecules by analyzing constituent bonds. The technology uses light radiation to study organic compounds.
Meteorology: measure the height of clouds, calculate the temperature of the earth and surface is possible if meteorological satellites are equipped with scanning radiometers.
Photobiomodulation: used for chemotherapy in cancer patients. Additionally, the technology is used to treat the herpes virus.
Climatology: monitoring the exchange of energy between the atmosphere and the earth.
Communication: An infrared laser provides light for optical fiber communication. These emissions are also used for short distance communication between mobile and computer peripherals.

3. UV sensor

These sensors measure the intensity or power of the incident ultraviolet radiation. A form of electromagnetic radiation has a longer wavelength than X-rays, but is still shorter than visible radiation.

An active material known as polycrystalline diamond is used to reliably measure ultraviolet. Instruments can detect various environmental impacts.

Device selection criteria:

Wavelength ranges in nanometers (nm) that can be detected by ultraviolet sensors.
Working temperature.
Accuracy.
power range.

Operating principle

The UV sensor receives one type of energy signal and transmits another type of signals. To observe and record these output streams, they are sent to electric meter. To create graphs and reports, the indicators are transferred to an analog-to-digital converter (ADC), and then to a computer with software.

Used in the following devices:

UV phototubes are radiation-sensitive sensors that monitor UV air treatment, UV water treatment, and solar exposure.
Light sensors - measure the intensity of the incident beam.
Ultraviolet spectrum sensors are charge-coupled devices (CCDs) used in laboratory imaging.
Detectors ultraviolet light.
Bactericidal UV detectors.
Photostability sensors.

4. Touch sensor

This is another large group of devices. The classification of pressure sensors is used to assess the external parameters responsible for the appearance of additional characteristics under the action of a certain object or substance.

The touch sensor acts like a variable resistor according to where it is connected.

The touch sensor consists of:

A completely conductive substance such as copper.
Insulated intermediate material such as foam or plastic.
Partially conductive material.

However, there is no strict division. The classification of pressure sensors is established by choosing a specific sensor, which evaluates the emerging voltage inside or outside the object under study.

Operating principle

A partially conductive material opposes the flow of current. The principle of the linear encoder is that the flow of current is considered to be more opposite when the length of the material through which the current is to pass is longer. As a result, the material's resistance is changed by changing the position in which it comes into contact with a fully conductive object.

The classification of automation sensors is based entirely on the described principle. Here, additional resources are involved in the form of specially developed software. Typically, software is associated with touch sensors. Devices can remember "last touch" when the sensor is disabled. They can register the "first touch" as soon as the sensor is activated and understand all the meanings associated with it. This action is similar to moving computer mouse to the other end of the mat to move the cursor to the far side of the screen.

5. Proximity sensor

Increasingly, modern vehicles are using this technology. The classification of electrical sensors using light and sensor modules is gaining popularity among automotive manufacturers.

The proximity sensor detects the presence of objects that are almost without any points of contact. Since there is no contact between the modules and the perceived object and there are no mechanical parts, these devices have a long service life and high reliability.

Different types of proximity sensors:

Inductive proximity sensors.
Capacitive proximity sensors.
Ultrasonic proximity sensors.
Photoelectric sensors.
Hall sensors.

Operating principle

The proximity sensor emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (such as infrared) and waits for a response signal or changes in the field. The object to be detected is known as the target of the registration module.

The classification of sensors according to the principle of operation and purpose will be as follows:

Inductive devices: there is an oscillator at the input that changes the loss resistance to the proximity of an electrically conductive medium. These devices are preferred for metal objects.
Capacitive Proximity Sensors: These convert the change in electrostatic capacitance between the detection electrodes and ground. This occurs when approaching a nearby object with a change in the oscillation frequency. To detect a nearby object, the oscillation frequency is converted into a DC voltage, which is compared to a predetermined threshold value. These devices are preferred for plastic objects.

The classification of measuring equipment and sensors is not limited to the above description and parameters. With the advent of new models of measuring instruments general group increases. Various definitions have been approved to distinguish between sensors and transducers. Sensors can be defined as an element that senses energy in order to produce a variant in the same or a different form of energy. The sensor converts the measured value into the desired output signal using the conversion principle.

Based on the received and created signals, the principle can be divided into the following groups: electrical, mechanical, thermal, chemical, radiant and magnetic.

6. Ultrasonic sensors

An ultrasonic sensor is used to detect the presence of an object. This is achieved by emitting ultrasonic waves from the head of the device and then receiving the reflected ultrasonic signal from the corresponding object. It helps in detecting the position, presence and movement of objects.

Because ultrasonic sensors rely on sound rather than light for detection, they are widely used in water level measurements, medical scanning procedures, and in the automotive industry. Ultrasonic waves can detect invisible objects such as transparencies, glass bottles, plastic bottles and sheet glass, with their reflective sensors.

Operating principle

The classification of inductive sensors is based on the scope of their use. It is important to consider the physical and Chemical properties objects. The movement of ultrasonic waves differs depending on the shape and type of medium. For example, ultrasonic waves travel straight through a homogeneous medium and are reflected and transmitted back to the boundary between different media. The human body in the air causes significant reflection and can be easily detected.

The technology uses the following principles:

Multireflection. Multiple reflection occurs when waves are reflected more than once between the sensor and the target.
Limit zone. Minimum sensing distance and maximum distance triggering can be adjusted. This is called the limit zone.
detection zone. This is the interval between the surface of the sensor head and the minimum detection distance obtained by adjusting the scan distance.

Devices equipped with this technology allow scanning various types objects. Ultrasonic sources are actively used in the creation of vehicles.