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What Is a Proportional Counter?

A proportional counter is a type of radiation detector. It detects radiation by measuring the number of electrons (electric current) produced by the ionization of gas molecules when energetic particles pass through a gas.

Ionization chambers and GM (Geiger-Müller) counters are radiation detectors based on similar principles, but they differ in the magnitude of the voltage applied to measure the current. Ionization chambers operate at lower voltages than proportional counters, while GM counters operate at higher voltages than proportional counters.

Applications of Proportional Counters

Proportional counters detect radiation such as X-rays, α-rays, β-rays, γ-rays, and neutrons and measure radiation counts and energy. Because of their simple structure and relatively easy manufacturing, proportional counters are often used as detectors in academic research and other fields.

Generally, they are used to measure radiation dose in the air, especially for neutron detection and β-ray contamination detection. Proportional counters for X-rays are also sometimes incorporated as detectors in X-ray fluorescence film thickness meters, which are used for non-contact measurement of plating thickness, etc., because of their larger incident window and higher efficiency compared to semiconductor detectors.

Principle of Proportional Counters

The proportional counter is usually a cylindrical aluminum vessel filled with a mixture of inert gases such as argon, helium, or neon, and methane or butane and operated by applying high voltage to wires stretched inside the tube. The cylindrical vessel has an incident window through which radiation enters the tube.

When the incident radiation passes through the gas, the gas along its path is ionized to produce electrons and cations. The electrons produced are called primary electrons. The primary electrons are accelerated by the electric field in the tube and ionize the gas anew, and these ionized electrons cause further ionization, resulting in a phenomenon called gas amplification in which the number of electrons increases explosively. The amplified electrons flow into the wire inside the tube and are detected as an electrical pulse.

Since the number of amplified electrons is proportional to the energy of the incident radiation, this detector is called a proportional counter. The amplification rate of electrons depends on the type of gas and the applied voltage, but if the gas and voltage are known, the energy of the incident radiation can be measured.

An ionization chamber operates on a similar principle to the proportional counter but operates at a lower voltage and therefore does not amplify the gas. Therefore, proportional counters have the advantage of higher sensitivity than ionization chambers. On the other hand, proportional counters have the disadvantage that they cannot measure the number of primary electrons as accurately as an ionization chamber, and their energy resolution is inferior.

What Is a High Frequency Power Supply?

A high frequency power supply is a power supply that outputs a constant voltage with a frequency ranging from several kHz to several hundred kHz.

Power supply types are classified according to their switching elements, with some using transistors and others using vacuum tubes. The vacuum tube method has been used for a long time and uses a large transmitter tube and transformer, so the size of the power supply is large.

On the other hand, the method using transistors has recently seen the development of inverters that use elements called MOSFETs, and the advantages are smaller size and higher power supply output efficiency. High frequency power supply is mainly used to heat objects using a method called induction heating.

Industrial applications include quenching, ERW pipe welding, thin steel plate heating, plasma generation, and cleaning.

Uses of High Frequency Power Supplies

High frequency power supplies are used to generate eddy currents to heat objects in high frequency induction heating. Specific applications are as follows:

• Microwave and electromagnetic induction heating
• Plasma generation
• Surface modification
• Cleaning

Used in semiconductor and LCD manufacturing, MEMS manufacturing, solar cell manufacturing, plasma cleaning, steel and forging industries. It is also increasingly used in the new materials industry, food manufacturing, building materials manufacturing, wood drying, medical thermotherapy, electronics, automotive, vinyl fusion, and other industrial fields.

High frequency power supplies for plasma generation excite plasma by means of a high frequency electric field, thereby heating the ions and electrons that form the plasma. By irradiating the surface of polymer materials and other materials, they can be used to select the type of functional group and control the radical species on the surface, which is also used in the development of functional materials.

Principle of High Frequency Power Supplies

To generate a high frequency power supply, the input AC power supply must be converted once to DC, passed through an inverter, and then converted again to AC. First, the AC power supply is converted to DC using bridge diodes.

A bridge diode is an element consisting of six diodes connected in a bridge. By inverting the negative voltage side of the AC power supply, a DC voltage can be output. Next, the DC voltage is converted to a square wave using a switching element, and this square wave is connected to a matching transformer.

The voltage is then converted according to the number of transformer windings, and finally converted to AC power in a resonant circuit.

Types of High Frequency Power Supply

High frequency power supplies (inverters) are classified according to their switching elements.

1. Thyristor Inverter

Thyristors are used as the oscillator element. They are suitable for commercial power supply frequencies up to 10 kHz and high voltages, and have a large element.　　　

2. Bipolar Transistor Inverter

Suitable for small oscillators 500W to 2kW. The element is small and is used for handy types, etc.

3. IGBT Inverter

GBT stands for “Insulated Gate Bipolar Transistor.” The elements are large and suitable for high-current applications and series resonance circuits. The frequency range is: 10kHz to 50kHz, for high output.

4. MOSFET Inverter

MOSFET stands for “Metal-Oxide-Semiconductor Field Effect Transistor.” It is suitable for high-frequency applications and is smaller than other devices. Frequency range is 100kHz to 400kHz, so it is not suitable for high output power.

5. Vacuum Tubes

Vacuum tubes are suitable for high-frequency applications, self-excited oscillation type with frequencies ranging from 100 kHz to 10 MHz. They use a large transmitter tube and a large transformer, so the equipment becomes larger.

Other Information on High Frequency Power Supply

Types of Power Supply Control

1. Voltage Control
This control method uses thyristors or other elements to suppress DC voltage. It is suitable for quenching because the frequency is fixed and the current penetration depth can be fixed.

The circuit is complex and expensive because of the need for flattening with a power supply capacitor.

2. Current Control
On the oscillator side, the output current value is constant because the frequency is varied by automatically adjusting the load resistance to match the indicated current value. Therefore, the oscillator frequency is always changing.

3. Power Control
The input power value is calculated by multiplying the voltage and current value of the DC section. The output is then controlled with respect to the indicated value.

4. PWM Control
This is a control method found in small oscillators. It is a control method in which the pulse width (duty ratio) is varied while the period remains constant.

What Is a Dew Point Hygrometer?

The dew point is the temperature at which condensation occurs when a gas is cooled. A dew point hygrometer is used to measure the dew point of the gas continuously.

The first application where dew point measurement is needed is in dryers. A low dew point means less moisture in the air, so moisture can be efficiently removed from items that need to be dried.

In the industrial gas industry, a high dew point also means that there is more moisture in the air.

When used outdoors, the low temperatures can lead to condensation and freezing. Therefore, the dew point is always measured with a dew point hygrometer.

Uses of Dew Point Hygrometers

The first use of dew point hygrometers is in dryers. The word “dryer” may bring to mind a machine that dries food at high temperatures, but some foods may deteriorate under high temperatures.

Therefore, it is necessary to dry them at low temperatures, and in doing so, it is essential to expose them to air with a low dew point, so the dew point is constantly measured with a dew point hygrometer.

In other industries, there are also machines that do not like moisture or whose efficiency is reduced by moisture.

When supplying nitrogen or oxygen to such machines, the dew point is always measured with a dew point hygrometer.

Principle of Dew Point Hygrometers

A dew point hygrometer is an instrument that measures the moisture content in the air. The dew point hygrometer can be broadly divided into two types of measurement methods: the capacitance type and the mirror-cooled type.

The capacitance type is easy to measure and is used in portable devices. On the other hand, the mirror-cooled type is highly accurate and can be used for applications requiring high accuracy.

As the name suggests, the capacitance type uses electricity to detect moisture. The capacitance type has a very thin sensor inside, on which a special metal is deposited. When moisture adheres to the sensor, the resistance value changes depending on the amount of moisture. This change in resistance is output from the sensor as the amount of moisture.

As the name implies, the mirror-cooled type uses a mirror. In the mirror-cooled type, the gas whose dew point is to be measured is sprayed onto the mirror surface inside the instrument. Cooling then causes condensation to form on the mirror surface, and heating the mirror surface eliminates the condensation.

The dew point is output by repeating this process to find the best balance. Therefore, highly accurate measurement is possible, but it takes some time.

What Is a Linear Gauge?

A linear gauge is a measurement device that determines the displacement of an object. It utilizes optical methods to measure displacement, involving a moving slit attached to the object, two fixed slits, and a machine that converts the slit waveform into a pulse wave. The displacement is interpreted from the number of wave pulses, with accuracy dependent on slit spacing.

Applications of Linear Gauge

Linear gauges are primarily used in machine tool control across various industries, including automotive, home appliances, machinery parts, logistics, and research. Selecting the right gauge involves considering its accuracy, environmental suitability, and mountability.

1. Machine Tools

In machine tools, such as lathe equipment and milling machines, linear gauges measure shaft rotation speeds and the travel of cutters and drills.

2. Load Displacement Measurement

They are used to measure displacement under a constant load, such as in testing the strength of automobile bodies or doors.

Principle of Linear Gauge

Linear gauges function by detecting changes in light patterns caused by the movement of the object.

1. Calculation of Displacement

Displacement is calculated based on the light passing through the moving slit and its variation in relation to the fixed slits.

2. Orientation Calculation

The gauge calculates the direction of movement by observing the phase shifts in the light pattern between the moving and fixed slits, outputting two square wave signals with a 90° phase difference.

Structure of Linear Gauge

A linear gauge comprises a detection part with a light source and slits and a counting section that transforms light waveforms into pulse waves.

1. Detection Part

The detection part includes a light source, two fixed slits, and a moving slit attached to the measured object. The fixed slits are offset to discern the movement direction of the moving slit. The output signal is either 4um or 40um per pitch, depending on the resolution type.

2. Counting Section

The counting section, consisting of a light-receiving element and a counter, multiplies the signal to achieve a measurement resolution of a quarter pitch.

Other Information on Linear Gauge

1. Indication Accuracy

Indication accuracy refers to the measurement error of the linear gauge, calculated over the entire length of the moving slit’s travel.

2. Temperature Effect

Accuracy is affected by temperature. The linear expansion coefficient of the glass scale used in the detection section is considered to calculate indication accuracy at different temperatures.

What Is a Power MOSFET?

Power MOSFET is a generic term for MOSFET devices for high-power applications. MOS stands for Metal Oxide Silicon.

In the past, bipolar transistors with base, collector, and emitter terminals were the main switching devices. In comparison, MOSFETs have faster switching speed, lower voltage, and lower on-resistance, enabling low-loss operation.

Uses of Power MOSFETs

Power MOSFETs can be used as a substitute for bipolar power transistors in circuits that conventionally use bipolar power transistors. In particular, Power MOSFETs have lower switching losses than bipolar power transistors.

The high on-resistance and low breakdown voltage of MOSFETs and the difficulty of applying them to high-power circuits have all been overcome by recent technological innovations such as the planar-gate double diffusion structure, trench gate structure, and super junction structure, and now power MOSFETs have become the most popular power transistor in the world.

MOSFETs are now the mainstay of the power transistor world.

Principle of Power MOSFET

Power MOSFETs, by their very principle, operate only with a large number of cores (electrons for n-type transistors and holes for p-type transistors). Therefore, they are not affected by the minority carrier like the bipolar type, which has been the mainstay of power transistors in the past. Fundamentally, they have a higher input impedance than junction-type FETs, so recent Power MOSFETs are more difficult to break than conventional ones.

Power MOSFETs can be broadly classified according to their gate structure and drift layer structure, and the three major structures that have prevailed in recent years are described below.

1. D-MOS Double-Diffused MOSFET Structure

This structure achieves high breakdown voltage by double-diffusion channel formation, resulting in a high-performance Power MOSFET with high integration, low ON-resistance, and low loss.

Specifically, in the case of an N-channel MOSFET, a low-concentration p-type layer and a high-concentration n-type layer are formed by double diffusion on an N-substrate epitaxial layer.

P-channel MOSFETs are also available, but the mobility of holes is smaller than that of electrons, resulting in higher on-resistance and degraded characteristics.

2. Trench Gate Structure

The trench gate structure is a U-groove gate structure in which the channel is formed vertically to achieve higher integration and lower ON-resistance. However, this structure is used for low-voltage Power MOSFETs.

The unit cell area is reduced by U-grooving the gate.

3. Super Junction Structure

This is currently the best Power MOSFET available, except for the change in substrate material. The periodic vertical p/n structure called super junction is formed in the drift layer to achieve ultra-low ON-resistance below the silicon limit of conventional Power MOSFETs.

Other Information on Power MOSFETs

Scope of Use of Power MOSFETs in the Market

Power MOSFETs are used in high-power power supply applications at relatively low cost due to their low cost and high reliability on silicon substrates. However, when it comes to high-power power supply applications that handle several kVA, the on-resistance increases to several ohms, which significantly increases losses and takes them out of the usable range.

Currently, the semiconductor devices mainly used in this area are IGBTs (Insulated Gate Bipolar Transistors) or SiC Power MOSFETs, which are used in combination with bipolar transistors to suppress the increase in on-resistance in the high-current region of MOSFETs.

The SiC power MOSFET is a power MOSFET with a bipolar transistor and a SiC power MOSFET.

SiC Power MOSFETs are characterized by the use of SiC compound semiconductors, which are wide bandgap crystals, as the substrate material, and by the dramatic improvement in breakdown voltage. MOSFETs are used for high power and high speed switching power supply applications at several 100KHz.

IGBTs are not suitable for high-speed switching power supplies due to their device structure, while SiC Power MOSFETs are used because of the relatively high cost of SiC substrates (due to wafer size limitations and other factors). Nevertheless, Power MOSFETs on silicon substrates, which are relatively inexpensive and easy to use, will continue to be used in the mid- to low-power range, with improvements in characteristics and cost, unless new devices emerge that can replace them.

What Is a Touch Switch?

A touch switch is a switch that is turned on and off by touching the screen with a user’s finger or pen.

Various detection methods are available, such as capacitive, resistive, and infrared, and are used according to the application. Compared to buttons and keys, switches can be placed on a flat surface and are superior in design, so they are widely used in operation panels of AV equipment and industrial equipment, and in operating units of public equipment.

It was also a pioneer in touch operation even before the appearance of touch-operated products such as smartphones and tablets. Recently, smaller and thinner touch switches are required to accommodate the miniaturization of mobile devices and the IoT.

In the development of touch switches, reliability and cost performance, as well as improved operability, have become important factors.

Uses of Touch Switches

Touch switches that we often see in our daily lives are mainly intended for human operation. Examples include pushbuttons for electrical appliances in homes, elevators in shopping malls, and automatic doors. Recently, capacitive touch switches that are activated simply by touching the screen, such as smartphones and touch panels, are becoming the mainstream.

Touch switches are also widely used inside industrial robots and machine tools. At hazardous sites such as factories, they also serve as safety devices to prevent workers from entering or being pinched and to detect damage to tools.

Principle of Touch Switches

As the name suggests, touch switches are operated by touching. The most appropriate type of touch switch should be selected according to the operating environment and purpose.

1. Capacitive Touch Switch

Capacitive touch switches utilize the fact that the human body is a conductor of electricity. When a finger approaches the surface of the switch, the capacitance changes, and the switch turns on or off by detecting this change. This technology is often used in touch screens for smartphones and tablets.

2. Resistive Touch Switches

Resistive touch switches have two conductive layers with an insulating layer in between. When the user touches the surface, the two conductive layers come into contact and an electric current flows. The change in this current is detected and the operation of the switch is controlled.

3. Infrared Type Touch Switch

Infrared touch switches use an infrared sensor to detect the proximity of the user’s hand or finger. The sensor emits infrared light and detects the reflected light. As the hand or finger approaches, the amount and angle of the reflected light changes, and the switch operates based on this change.

Types of Touch Switches

Touch switches are used in many situations, and their range of application is expanding every day. However, not all touch switches are the same.

It is important to select the most appropriate type depending on the specific application and environment.

1. Low Power Type

This is a touch switch with extremely low power consumption. Suitable for battery-powered portable devices.

2. High Durability Type

This type can maintain high performance for a long period of time. Often used in industrial applications and public facilities.

3. Multi-Point Type

This type of touch switch can detect multiple touch points simultaneously. Often seen in smartphones and gaming devices.

4. Other

Types that operate stably even in environments with a lot of moisture or dirt are useful in kitchen appliances and medical equipment. Some types can also be customized for specific applications or special environments. They are used in multifunctional operation panels and special industrial applications.

What Is a Board-to-Board Connector?

Board-to-Board Connector is a connector used for high-density mounting of printed circuit boards.

Among these connectors, those that are designed to allow the connected connectors to move in three directions (pitch, row-to-row, and mating) or to move in either direction to suppress the effects of mating misalignment are called floating connectors.

By combining a socket and a plug, the connector can move in the x-y-z three-dimensional direction, making it less susceptible to pry (shock) and misalignment.

Applications of Board To Board Connector

Board-to-Board Connectors are used in response to the recent trend toward miniaturization of equipment, and can directly connect boards together. Because of this advantage, Board-to-Board Connectors have a wide range of applications, including computers, portable information devices, digital TVs, automobiles, and industrial machinery and infrastructure.

In recent times, as electronic devices have become increasingly sophisticated, demand for more advanced and precise Board-to-Board Connectors has been increasing.

Principle of Board-to-Board Connector

Board-to-Board Connectors use pins and sockets to connect boards. The function of the pins and sockets is to connect and separate the boards through electrical contact and mechanics.

This ability to separate and join allows equipment to be configured as a unit, which is an advantage over permanent connections such as soldering or screwing. The structural design of the product and the ease of mass production enable a reduction in the total cost of ownership. It also improves maintainability, such as parts replacement and inspection, leading to stabilization of performance and quality.

How to Select Board-to-Board Connector

Board-to-Board Connectors are available in two types: the stacked type, in which the boards are stacked top to bottom, and the stand-up type, in which one of the boards is used standing up for connection. Since the shape of the connector changes depending on the direction in which the boards are connected, first consider which direction you wish to connect the boards.

There is also a bottom-entry type in which the pins penetrate from the underside of the connector. While they have the disadvantage of low mounting density, the distance between boards can be set freely. Because of this characteristic, they are used in products that have heat-generating components on separate boards.

When selecting Board-to-Board Connectors, it is necessary to confirm that the current value, withstand voltage, insulation, etc. meet the circuit specifications. In the case of circuits that require micro level and high reliability, it is also important to check the material.

Other Information on Board-to-Board Connector

1. Advantages of Board-to-Board Connector

Board-to-Board Connectors are used when additional circuits can no longer be placed on the printed circuit board during the design process. Other times, when several boards with slightly different functions are combined into one board, the boards with different functions are treated as optional boards.

The Board-to-Board Connector enables the use of a single type of board to realize the functions of multiple products by installing and removing optional boards. Normally, cables are used to connect boards to boards, but when boards are connected by cables in this way, the space occupied by the board in the equipment becomes large.

Board-to-Board Connectors are useful in meeting the need for miniaturization, since this is an obstacle when miniaturizing products. This connector can be used when circuits do not fit on a single board, when boards of different sizes are mounted, or when boards need to be joined together because of the miniaturization of the product.

2. Cautions for Board-to-Board Connector

When joining boards, it is necessary to make sure that the joints of the boards match each other in terms of the number of pins, etc. In addition, connectors only have the function of joining boards together and do not have a large mechanical support force for the boards.

Therefore, a separate mechanism to support the board with screws or other means is required. Although this connector facilitates maintenance of the board, careful handling is required to prevent excessive force from being applied to the board and damaging it when the connector is removed.

What Is a Tilt Sensor?

Tilt Sensor is a device that detects the inclination of an object to be measured.

It measures the inclination from the horizontal position and detects the tilt, angle, or slope of the object to be measured. 

It measures the tilt from the horizontal position with respect to gravity and displays the tilt, angle, or gradient of the object. Tilt Sensors are also called Angle Sensors. Tilt Sensors strictly refer to the tilt detection part only, and there are other types of Tilt Sensors, such as inclinometers, to which electronic devices are added to adjust input and output.

Uses of Tilt Sensors

Tilt Sensors are used for tilt detection and posture control. Specifically, they are used to maintain the level of construction equipment beds, detect the tilt of cranes, and adjust the illumination angle of automobile headlights. They are also used to check the level of land and rooms, and to automatically rotate smartphone screens.

Strictly speaking, Tilt Sensor refers only to the element that detects inclination, and when an electronic device that adjusts input and output is added, it is called an inclinometer. However, devices that include an input/output device and an arithmetic device are also conventionally called Tilt Sensors.

Principle of Tilt Sensor

Tilt Sensors are devices that detect inclination by generating an electrical output when the object being measured is inclined. Tilt occurs in the uniaxial, biaxial, and triaxial directions, so it is important to select a Tilt Sensor according to the number of axes of inclination to be detected.

In addition, Tilt Sensors have changed from the switch form that switches on and off when an inclination is detected, which was often used in the past, to those that combine sensing technology, which have become mainstream in recent years. The methods used to detect the tilt of Tilt Sensors include the electro-electrolytic and MEMS, which have been used since the early days. In recent years, the MEMS type has become the mainstream in terms of accuracy and response time.

1. Electrolytic Tilt Sensor (Electrostatic Tilt Sensor)

The electrolyte type Tilt Sensor uses the property of a liquid surface to always be horizontal to detect the tilt of the liquid as a change in electrostatic capacitance. Specifically, the sensor consists of a cylindrical body with an internal cavity in which electrolytic solution (conductive liquid) is sealed at a depth of about half its length, and electrode plates facing each other in the longitudinal direction.

In other words, the corresponding electrodes are half submerged in the electrolyte in the longitudinal direction. When the cylindrical body is tilted with voltage applied between the electrode plates and the electrolytic solution in the cavity is kept horizontal on its axis in the longitudinal direction, the internal resistance in the circuit changes due to the difference in the portion of the opposite electrode that is immersed in the liquid. The tilt detection of the electrolyte Tilt Sensor is performed by detecting this change in the internal resistance of the circuit and converting it to an angle.

However, it has the disadvantages of a relatively slow response time and a tendency to be affected by vibration of the liquid surface. The electrolyte type Tilt Sensor can detect tilt in two axes by arranging two pairs of electrodes orthogonally to each other.

2. MEMS (Micro Electro Mechanical Systems) Tilt Sensor

The MEMS Tilt Sensor is an inclination sensor that utilizes micro-electromechanical system technology. The MEMS Tilt Sensor consists of a pair of fixed electrodes and a spring-loaded movable electrode between the fixed electrodes.

When the MEMS Tilt Sensor is tilted about the support direction of the fixed and movable electrodes, the fixed electrodes do not move, while the movable electrodes move in the direction in which the sensor is tilted. In other words, the capacitance between each fixed and movable electrode changes. This change in capacitance is detected and converted to an angle.

If movable electrodes are installed orthogonally to the XY direction and each is sandwiched between a pair of fixed electrodes, inclination in two axial directions can be detected.

3. Other Methods

Other methods used in Tilt Sensors include the pendulum type and the quartz crystal type.

Pendulum Tilt Sensor
Pendulum Tilt Sensors have a pendulum and a sensing element such as a magnetoresistive element inside the body. The pendulum Tilt Sensor detects changes in the magnetic field caused by the movement of the pendulum when the main unit is tilted, and calculates this into an angle of inclination.

Quartz Tilt Sensor
The Quartz Crystal Tilt Sensor is a highly sensitive Tilt Sensor that utilizes the characteristics of a quartz crystal. A cantilever made of processed quartz crystal and a holding part are fixed at one end facing each other, and an electrode is provided on each of the cantilever and holding part.

When the sensor is tilted, the cantilever deflects while the holding part does not. Because the cantilever deflects, the distance between the electrodes changes and the capacitance also changes. The capacitance is measured as a change in frequency, which is how the quartz tilt sensor works. The conversion from capacitance to frequency is achieved by combining the Tilt Sensor with a quartz crystal and a transmitter circuit.

Other Information on Tilt Sensors

Acceleration Sensor

Similar to the Tilt Sensor, the Acceleration Sensor is a sensor that detects tilt. The Tilt Sensor outputs the sensor output itself with information on the angle of inclination. Because of its low frequency fluctuation, the tilt sensor is effective for measuring the tilt angle in slow motion or in a stationary state. Acceleration sensors, on the other hand, detect acceleration applied to an object.

Using Newton’s law of motion, which states that acceleration acting on an object is proportional to external force, acceleration sensors are used to measure acceleration itself or to detect the application of external force. Since acceleration itself can be detected, it is used in gravity and seismic measurements. Since it can also detect the application of external force, it can detect movement in front-back and left-right directions in addition to the direction of gravity, such as tilt, vibration, movement, impact, and fall. Compared to the Tilt Sensor, it has a wider frequency bandwidth and can also measure fast movements.

Because of these differences, Tilt Sensors are used, for example, to prevent cranes and construction vehicles from tipping over. Acceleration sensors, on the other hand, are used, for example, in applications that change the vertical and horizontal display of a smartphone to match the environment in which it is used.

What Is a Signal Converter?

A signal converter is a device that transforms electrical signals from various sensors into industrial current signals.

Sensors gather information, such as temperature, load, or the number of revolutions of a machine’s rotating shaft, and convey it as measurement data. This data is then transmitted to control equipment, which uses it to output commands and control the system.

Signal converters adapt the electrical signals from sensors into a format compatible with control equipment. They also isolate abnormal electrical signals from sensors to prevent damage to downstream control devices.

There are many types of signal converters, each playing a crucial role in transmitting sensor information to control systems and devices.

Uses of Signal Converters

Signal converters are essential in electronics that utilize various sensors. Their applications range from industrial manufacturing machinery to laboratory instruments and measurement devices.

They are also employed in factory processing furnaces for heating or cooling, in equipment for controlling turbine, spindle, and shaft speeds, in load measurement for machine tools, and test equipment.

Principle of Signal Converters

The operation principle of signal converters varies by type:

1. Isolator

Isolators disconnect signals from the electrical circuit between the sensor and control circuit, preventing signal routing issues, protecting equipment, reducing noise effects, and facilitating signal exchange between different manufacturers’ equipment.

2. Pulse Transducers

Pulse transducers convert signals from proximity sensors into analog signals for rotational speed control. They transform pulse signals detected by proximity sensors into analog signals for output.

3. Couple Transducers

Couple transducers, used for temperature measurement, convert the electromotive force (emf) signals from thermocouples into analog signals for output.

4. Load Cell Transducers

Load cell converters transform the resistance changes in strain gauges, caused by force-induced deformation, into analog electrical signals for measuring force magnitude.

Other Information on Signal Converters

Signal Converter Cautions

It’s crucial to consider noise countermeasures for signal converters. They should be installed away from high-frequency and surge-generating devices and, where necessary, supplemented with surge absorbers and noise filters to mitigate interference from motors, transformers, solenoids, and magnet coils.

What Is a Torque Sensor?

Figure 1. Appearance of a Torque Sensor

A torque sensor is a device that measures torque, the force that causes a shaft to rotate, as illustrated in Figure 1.

It converts the slight twist of a shaft under torque into a measurable output, displaying the torque value. Torque sensors are crucial in various scenarios requiring torque measurement, including torque management in production lines and evaluating the performance of industrial machinery.

While it may also be referred to as a torque gauge or torque meter, there are no strict naming conventions. This article will use “torque sensor” consistently regardless of application.

• Torque Sensor
  A device used in electric bicycles and robots to control motors or robots based on detected torque.
• Torque Gauge
  A device for measuring the tightening torque with tools like screwdrivers and instantly checking the torque value on a display.
• Torque Meter
  A device for assessing motor torque in motor testing setups.

Uses of Torque Sensors

Torque sensors are commonly used in electrically powered bicycles, where they detect the pedal force (torque) applied by a cyclist. The motor then provides the necessary assistance based on this torque, easing the pedaling effort.

In industrial settings, torque sensors are vital in quality control and research testing.

1. Quality Control

Torque sensors are utilized mainly in:

• Spot Checks
  Examining how tightly container caps are sealed during production.
• Periodic Inspections
  Ensuring electric screwdrivers on the production line operate within expected parameters before work commences.

2. Test and Research

In testing and research, torque sensors are mainly employed in:

• Strength Measurement
  Assessing test materials and components for torsional strength.
• Motor Performance Evaluation
  Determining motor performance under various loads.
• Rotational Torque Measurement of Machinery
  Measuring the torque in machinery, such as rotary printing press rollers, to find optimal operating conditions.

Principle of Torque Sensors

The operation of torque sensors involves the following steps:

1. A torque is applied to the shaft.
2. This torque induces torsion/strain on the shaft.
3. The shaft’s torsion/strain is measured.
4. The torque on the shaft is calculated from this measurement.

The measured torsion/strain is converted into an electrical signal, often amplified by an amplifier for easy interpretation and displayed by an A/D converter. Some sensors come with a display for immediate torque reading.

Types of Torque Sensors

Various methods exist for measuring shaft torsion and strain, with the following four being prevalent in current torque sensors:

1. Strain Gauge Type Torque Sensor

Figure 2. Axis of Strain Gauge Type Torque Sensor

This method employs strain gauges to measure shaft strain due to electrical resistance changes during expansion and contraction. As depicted in Figure 2, tensile and compressive stresses occur at ±45° angles when torque is applied, which is measured by strain gauges.

2. Capacitive Torque Sensor

This method gauges shaft strain through capacitance changes between two electrodes on the shaft, affected by its warping.

Due to its simpler structure and shorter shaft requirement, it’s widely used in robotic torque sensors.

3. Magnetostrictive Torque Sensor

Here, shaft strain is measured by detecting inductance changes in a coil due to the inverse magnetostrictive effect when torque is applied, altering the magnetic permeability.

Advantages include non-contact measurement capabilities, making it suitable for rotating shafts without compromising shaft integrity.

4. Optical Torque Sensor

An optical sensor measures shaft strain by detecting changes in light amount due to emitter and receiver displacement under torsion or distortion.

Other Information on Torque Sensors

Products With Built-in Torque Sensor

Advancements in technology have led to the miniaturization of torque sensors, integrating them into industrial products. Here are examples:

1. Motor With Built-in Torque Sensor
Integrates a motor, reduction gear, and torque sensor for compactness and accurate torque measurement for smoother operation and safety enhancement through human contact detection.

2. Torque Sensor for Robots

Figure 3. Torque Sensor Built Into the Cooperative Robot

Articulated robots with integrated torque sensors, especially in cooperative robots, enable precise control of force and detection of human or obstacle contact.