カテゴリー: category_usa

What Is an Industrial Microscope?

Industrial microscopes are used for process inspection and analysis in the manufacture of semiconductors, electronic components, and liquid crystal displays.

To facilitate data analysis, most industrial microscopes are equipped with a digital camera or CCD to capture images on a PC.

Uses of Industrial Microscopes

Industrial microscopes are used for manufacturing process inspection and analysis of industrial products, such as semiconductors and electronic components. The most common industrial microscope is the metallurgical microscope, which is used to observe surfaces by irradiating light and using reflected light.

Metallurgical microscopes are used for surface observation of opaque industrial products, such as ceramic structures, metals and alloys, polished surfaces of components, and electronic parts. They are also used for development, analysis, and inspection during the manufacture of products such as magnetic heads, liquid crystals, and films.

It can also be used for detailed observation of solder joint surfaces on circuit boards and the depth of penetration of welds. They are also used for evaluation and analysis after casting, heat treatment, and metallurgy in metal processing.

Principle of Industrial Microscope

The two most common types of industrial microscopes are the upright microscope, which is used to view the sample from above, and the inverted microscope, which is used to view the sample from below. The upright microscope is the most common and common type of microscope. The sample is placed under the objective lens and observed from above the objective lens. In an inverted microscope, the tip of the objective lens is on the upper side and the specimen is observed from below.

In both upright and inverted microscopes, the light source is located inside the objective lens. The light source illuminates the surface of the sample, and the reflected light from the sample surface is used to observe the shape of the sample surface. A prism or lens is placed between the objective lens and the eyepiece lens, and the light irradiated from the objective lens side to the sample and reflected back is magnified for observation. Magnification ranges from 50x to 1,000x.

There are many types of metallurgical microscopes used for Industrial Microscopes that have multiple functions, and there are a wide variety of models that can perform bright-field, dark-field, and differential interferometry with reflected illumination. In the dark-field method of reflected illumination, fine scratches, cracks, and pores appear shining and are suitable for observation of the specimen surface. In the differential interference method with reflected illumination, fine irregularities that are difficult to detect with the bright-field method can be detected, and it is widely used in inspection processes.

Types of Industrial Microscopes

As mentioned above, there are two types of industrial microscopes: upright microscopes and inverted microscopes.

1. Upright Microscope

In general, upright microscopes have the advantage that both transmission and reflection can be selected according to the illumination method, and the optical system can be easily designed.

2. Inverted microscope

Inverted microscopes are often used in the field of metals, etc., because the surface to be observed is placed in a downward position, allowing the observation surface to be easily leveled with respect to the optical axis.

Other Information on Industrial Microscope

1. Industrial Microscope With Multiple Functions

Industrial microscopes have not only the function of a metallurgical microscope but also other functions for efficient observation. For example, some models have multiple observation methods, including ordinary optical microscopes, polarizing microscopes, and scanning probe microscopes.

In addition, since industrial microscopes are used for manufacturing process inspection and analysis of industrial goods, they are generally capable of importing CCD or digital camera images into a PC. This facilitates data analysis, thereby improving the efficiency of inspection and analysis.

Furthermore, there are Industrial Microscopes that combine several functions, such as a camera and 3D measurement, in addition to the microscope function.

2. Difference Between Industrial Microscope and Measuring Microscope

An industrial microscope is, in a broad sense, a generic term for microscopes used in manufacturing and other industrial fields. Therefore, not only optical microscopes but also electron microscopes and digital microscopes fall under the category of industrial microscope. However, the industrial microscope generally refers only to optical metallurgical microscopes.

Metallurgical microscopes often use reflective illumination to shine light on the surface of the object to be measured, and their primary use is for surface observation. Measuring microscopes, on the other hand, use transillumination in addition to reflective illumination. In addition, the stage on which the object to be measured is placed is equipped with a digital scale and counter as standard equipment, and has mechanisms and functions for measurement.

In other words, industrial microscopes are mainly used for observation, and do not require the same amount of stage movement or magnification guarantee for the magnified observation image as measuring microscopes.

What Is a Dimensional Inspection System?

A dimensional inspection system is a highly functional visual inspection system that inspects the dimensions of mainly small electronic components such as LED substrates, CMOS sensor substrates, and ceramic substrates.

Dimensional inspection, a component of visual inspection equipment, is an inspection device that makes a pass/fail judgment as to whether a component or product is finished according to specifications. It is capable of measuring dimensions with micrometer-level precision, and by using the device for pass/fail inspections of finished products, it is possible to inspect the entire number of products.

In addition, by linking the conveyor system with image processing, an automatic dimensional inspection line can be constructed. Since image processing is equipped with a high-performance camera, it can be used to check the condition of intermediate products or for positioning during processing. They can also be used for dimensional measurement of metal parts as well as electronic parts.

Uses of Dimensional Inspection Systems

Dimensional inspection systems are often used for electronic components that require micron-level accuracy. Specifically, they are used to measure the edge width, alignment, register length, and other dimensions of coated sections in intermittent coating, stripe coating, and other processes of electrode sheets. It is also used to detect defects and uncoated areas.

Other uses of dimensional inspection systems include dimensional inspection of exterior wall boards, tiles, etc., and surface checks of lumber and after-extrusion processes. 3D dimensional inspection models can also be used to check the volume of minerals, food, etc.

Also, the equipment can measure parts that cannot be measured by human operators. For example, the inner and outer diameters of O-rings, the radius and angle of the tip of a metal part, and other difficult-to-measure areas can be measured using image processing.

Principle of Dimensional Inspection Systems

The dimensional inspection systems use a high-performance CCD or CMOS camera to perform inspections. Some models can scan laser beams and obtain height information to measure 3D XYZ axis dimensions.

On the production line, defective products identified as out of specification as a result of dimensional measurement using image processing is eliminated, and only the good products are automatically passed to the next process.

The work procedure for dimensional inspection systems begins by illuminating the object and capturing images with a camera through a lens. The image is then recognized by an image processor and measured.

1. Camera Selection

The number of pixels is selected according to the dimensional tolerances required for the inspection of the object to be measured. 

2. Illumination

There are three types of illumination: direct reflection type, diffuse reflection type, and transmission type, which are selected according to the surface condition of the object to be measured. 

3. Image Processing (edge detection)

Edges are the areas where color shading is often expressed in image processing. Differences in product height, material, color, and texture appear as edges. Dimensional inspection systems can measure the length and angle of areas that appear as edges, as well as the center position from the edge. Since the distance between edges is measured, the accuracy of the measurement depends on whether the edges are visible.

Other Information on Dimensional Inspection Systems

1. Appearance Inspection Equipment

Appearance inspection equipment is a device that can automatically inspect the appearance of a product. The visual inspection device is equivalent to a camera or other image sensor for visual inspection, and an image processing device or software replaces the brain. Since the numerical values listed in the judgment criteria are based on past data, it is easy to create standard values.

However, visual inspection equipment is not necessarily ready for operation immediately after installation. This is because inspection equipment requires preparation, and prior adjustment and confirmation take time. In some cases, it is difficult to set the sensor and light source positions for video and other sensors, as well as the judgment values for detecting foreign objects, and in some cases, the imaging software is unable to detect the foreign objects that it originally wanted to detect.

Such problems can be solved by repeatedly changing the hardware position settings to find the proper position. Even if the software setting detects an unexpected rejection the first time, it learns the data and updates the judgment data, including the next appropriate judgment value, so that the same rejection will not occur thereafter.

2. Image Dimension Inspection

Image dimensional inspection is a method that can instantly measure the height and depth of an object through images. In image sensor dimensional measurement, edges are detected by planning the object and measuring its position, width, and angle. In addition, mastery of the edge detection principle enables optimal detection to be set up.

Edge refers to the border between light and dark in an image, and edge detection is the detection of the border between these shades of gray using image processing. Edges are processed by the following processes.

(1) projection, (2) differentiation, (3) correction so that the maximum value of the differentiation is 100%, and (4) sub-pixel processing (interpolation calculation is performed on approximately three pixels centered on the maximum portion of the differential waveform from the waveform formed by those pixels to measure edge positions to the nearest 1/100th of a pixel).

One advantage of image processing is that it can automatically measure the dimensions of each part based on the captured data and save the numerical values as data. In addition, by performing dimensional inspection using image processing, the measured dimensions of each part can be saved as numerical values, and the data can be used for dimensional information management, shape analysis, and process improvement.

What Is a Safety Device?

A safety device refers to components that enhance safety in automated equipment. These devices are crucial when operating machine tools or manufacturing equipment that involves large movements, significant forces, or rotating parts, as they mitigate the risk of accidents, such as entrapment. Commonly, safety measures include enclosing equipment within a safety fence to prevent direct access.

Nevertheless, a safety fence alone may not suffice if workers inadvertently open the fence and approach the equipment. To address this, many machine tools and manufacturing setups integrate safety devices that halt operation if the safety fence is breached. These components are what constitute safety devices within safety equipment.

Uses of Safety Devices

Safety devices are integral to manufacturing equipment and machinery with high accident risks, ensuring safety protocols are observed. For instance, large robots operating at high speeds in mass production lines pose potential injury risks to workers due to the lack of human detection. Employing safety devices like door switches on safety fences and sensor-based equipment, such as light curtains, minimizes these risks. These devices, often referred to as “interlocks,” ensure equipment ceases operation upon the opening of a door or cover.

Principle of Safety Devices

A common example of a safety device is the door switch. It operates by having switches on either side of a door, disrupting the electrical circuit when open and completing it when closed. Door switches come in mechanical forms, where contact is made by a physical connection, and non-contact forms, which utilize a magnet within an actuator to operate reed switch contacts. This magnetic approach avoids the need for direct contact, offering versatility in applications. Unlike circuit-interrupting safety devices, analog solutions like covers or lids physically block access to moving parts, further enhancing safety.

Incorporating an emergency stop button, independent of the main control system, is essential for immediate halts in emergencies, ensuring operational safety even if the main control system fails.

Types of Safety Devices

Common safety devices include:

1. Safety Switches

Used for machine operation control, allowing emergency stops. Examples include emergency stop switches and foot switches.

2. Safety Sensors

Monitor proximity around machines or detect a door or cover status. Photoelectric sensors and proximity sensors are typical examples.

3. Safety Speed Control Device

Control machine speed to reduce accident risks, adjusting speed according to work conditions.

What Is a Collaborative Robot?

Collaborative robots are robots that allow humans and robots to work in the same work area.

Conventional robots are mainly industrial robots that perform assembly and transportation at manufacturing sites for automobiles, for example, but they are installed in dedicated automation lines, and human access is limited to maintenance.

While such dedicated automation lines can dramatically improve productivity compared to manual operations, they tend to require a large initial investment, including design, and are less flexible compared to manual operations in case of minor problems or changes in production items.

In this situation, deregulation in 2013 made it possible to introduce collaborative robots, which work side-by-side with humans. Collaborative robots can work in the same work area as humans without safety barriers, thus helping to alleviate labor shortages. Compared to conventional dedicated automation lines, the initial investment can be reduced and additional robots can be introduced without stopping the operation of the line, making it easier for small and medium-sized companies to adopt these robots.

Currently, cooperative robots are used in a variety of manufacturing sites, including food, automobiles, and electronic components, and catering robots have also been developed and are increasingly seen in our daily lives.

Uses of Collaborative Robots

Collaborative robots are relatively small and can perform detailed work in a small workspace. Since they are generally equipped with cameras and image processing capabilities, they are used in a wide range of industries.

In particular, until now, parts have been manually inserted and supplied to the line with their orientation, position, etc. set, but with the acquisition of image processing capability, robots are now able to determine the color, shape, orientation, etc., of large numbers of parts, pick them, and supply them to the next process, making a significant contribution to productivity improvement.

Principle of Collaborative Robots

Collaborative robots are more flexible than conventional industrial robots, with 5-axis and 6-axis joints, and are capable of high-speed, high-precision work. Equipped with cameras and sensors, they can recognize not only objects but also the surrounding environment through image processing. Some models are equipped with buttons attached to the arm to control the robot’s movement instructions.

In addition, safety measures are taken to ensure that they work cooperatively in the same work area as humans. Many collaborative robots are rounded in shape to prevent injury to humans, and most of them have sensors that detect and stop operation when touched by a human.

Some robots are equipped with LED lights on the robot arm, for example, to indicate the robot’s status so that the operator can check the robot’s operation. Although the robots are designed with safety in mind, it is necessary to ensure safety through risk assessments by the companies that introduce the robots themselves.

Other Information on Collaborative Robots

When introducing a robot, whether it is an industrial robot or a collaborative robot, teaching is required to define the work operation and set the robot’s control system. There are several teaching methods as follows. 

1. Off-Line Teaching

Off-line teaching involves creating a program and installing it on the robot. Although it is possible to create a program if a PC is available, it is not created while checking the actual operation and environment, and there is a possibility of programming errors, making it more difficult to program complex movements or cases where multiple robots are working simultaneously. In response to this, the digital twin technology is being applied to reproduce realistic motions.

2. Online Teaching

Online teaching is a method to configure a program based on the robot’s operation history while operating the remote control at the actual site. Since various cases are assumed and implemented on the actual site, it is necessary to stop operation during this time.

3. Direct Teaching

In direct teaching, a person directly moves the robot by hand to make the robot learn the operation. The robot arm has a built-in force sensor, torque sensor, or servo motor capable of torque detection. This method automatically calculates the externally applied force, speed, and angle of rotation to compose a program, and is often used in collaborative robots in particular. 

4. Teaching Using AI

In recent years, technologies have been developed that utilize AI to create programs automatically by providing only work targets, making it possible to create work programs easily and in a short time.

What Is Structural Analysis Software?

Structural analysis software is a series of processes that calculate the physical quantities that change when loads are applied to the structure under analysis, and evaluate and analyze them based on the obtained calculation results.

The physical quantities calculated include deformation, internal forces (stresses), heat and vibration frequencies. The purpose of structural analysis software is to reduce the risk of failure by predicting the results before actually creating the desired structure.

It also provides hints on how to make a better structure. Structural analysis software can also be used to predict the results of large structures that cannot be easily tested.

Uses of Structural Analysis Software

Areas where structural analysis software is often used include the development and production of automobiles, the architectural and civil engineering fields, production studies of metal processing, and the development of rubber products.

1. Automotive

Structural analysis software is an indispensable technology in the development of today’s automobiles. Structural analysis software is used for many components to improve driving performance, ensure safety, conserve energy, and lower costs.

2. Architecture and Civil Engineering

Structural analysis software is used in the architectural and civil engineering fields to design the strength, earthquake resistance, wind resistance, and fire resistance of various buildings. In architecture, it is almost impossible to make prototypes like machine parts. Structural analysis software must be used effectively.

3. Metalworking

In metalworking, plastic forming and pressing are used. In the past, products with a high degree of difficulty were made by the experience of experienced workers. Today, the effective use of structural analysis software enables more advanced manufacturing as well as the transmission of skills.

4. Rubber Products

Rubber products are subject to large deformation under load and contact with other products during deformation. Among Structural analysis software, nonlinear analysis is often used.

Principles of Structural Analysis Software

Structural analysis software consists of the following steps: drawing the object to be analyzed, cutting the mesh, modeling, inputting physical quantities, analysis, and output.

1. Drafting the Object to Be Measured

The analysis target is drawn using CAD or other software. Mainly 3D CAD is used. If you are using a CAD software, it is recommended to check if the file format of the CAD software is compatible with the structural analysis software to be used. 

2. Cutting a Mesh

The analysis target is decomposed into a grid called a mesh. The accuracy of this decomposition will affect the accuracy and speed of the calculation, so care should be taken.

3. Modeling

To model the analysis object, it is common to consider the boundary surface of each mesh as a spring. 

4. Input Physical Quantities

Input Young’s modulus, specific heat, expansion coefficient, density, etc. of the object to be analyzed. These physical quantities should be measured in advance by experiments or other means. 5.

5. Analysis

There are several types of analysis: static analysis based on Hooke’s law, f=kx, and dynamic analysis based on Newton’s equation of motion, F=ma.

The concept of time exists in kinetic analysis, and it can be divided into implicit analysis, which is relatively easy, and explicit analysis, which solves complex simultaneous linear equations.

6. Output

Most structural analysis software can visualize the results of the analysis. By visualizing the results, it is possible to discover the displacements of the analyzed object and the locations where concentrated forces are applied.

Types of Structural Analysis Software

There are various types of Structural Analysis Software.

Typical examples are as follows:

1. Static Analysis

Static analysis software calculates the deformations and stresses in a structure when forces are applied to it. It provides hints on how to shape the part to be suitable for the way it is used.

2. Eigenvalue Analysis

Eigenvalue analysis calculates the eigenvalues of an object. Eigenvalue is the frequency at which resonance occurs, and if the eigenvalue is high, it can be determined that resonance is unlikely to occur.

In the case of precision equipment mounts, vibration affects their functions, so eigenvalue analysis is performed to determine the shape so that the eigenvalues are as high as possible. 

3. Heat Transfer Analysis

Heat transfer analysis calculates the heat distribution of an object. For example, by calculating the temperature distribution of a heater plate, the temperature uniformity can be predicted, allowing optimal design without fabricating parts.

Other Information on Structural Analysis Software

Points to Note About Structural Analysis Software

Structural analysis software is used to perform structural analysis, but there are a few items to keep in mind in order to obtain analysis results that are close to actual conditions.

1. How to Create a 3D model
Making the model exactly the same as the actual geometry may cause errors in mesh processing or take too much time for analysis, and may not produce good analysis results. Depending on what is to be analyzed, the model must be created in detail and the parts to be omitted must be used separately. 

2. Analysis Conditions
There are a variety of conditions, and if these settings are not properly made, analysis results will be far from the actual values. Even if the analysis software is excellent, if the model and condition settings are poor, results that are close to reality cannot be obtained.

It is important to attend seminars of analysis software companies and use methods that are appropriate for the software. If experiments are available, correlation between structural analysis software results and experimental results (collation analysis) is also an important technique.

What Is a High Voltage Connector?

Specifications of a high-voltage connector are classified into three categories.

• Coaxial high voltage connector (coaxial, triaxial)
• Multi-pole connectors for high voltage (multi-pole type)
• Mixed connectors for high voltage + low voltage (mixed type)

In connectors for high voltage, it is important to note the difference between Type A and Type Z regarding contact protection. Type A power is supplied from the receptacle side. Type Z power is supplied from the plug side.

Normally, the female contacts are protected and located at the back of the insulator, but in the case of the high voltage type, the male contacts are protected at the back, and in this case, the contacts of the type A plug are a female type.

Uses of High Voltage Connectors

For example, to connect PCBs in a PC or between these modular devices, connectors make it easier and faster to connect and separate devices because of the direct connection between circuits.

Therefore, mass production, division of labor for each functional unit at multiple production sites, and assembly and maintenance of system equipment can be easily realized, as can interfaces with peripheral devices and networks.

High-voltage connectors are used in medical, industrial, and aerospace equipment, among others, that are subject to high-voltage loads.

Principle of High Voltage Connectors

A connector is usually a two-piece structure, with a plug on one side and a receptacle on the other side, which together serve the connecting and separating functions of the connector.

Both the plug and receptacle consist of a contact that conducts electricity, an insulator made of plastic that holds the contact and serves as insulation between the contacts, and an outer shell component called a shell that protects the insulator.

The contacts, which are the key components of the connector, are both made of highly conductive copper alloys, with non-springing pin contacts on the plug side and spring-loaded socket contacts on the receptacle side to accept the pin contacts.

The basic function of a connector consists of electrical contact and connection as a static contact, and mechanical coupling and separation. Since the signal connection is made electrically, it is used when improved workability is desired, as opposed to methods such as screwing with bolts and nuts, which irreversibly connect conductors.

High-Voltage Coaxial Connectors

High-voltage coaxial connectors are one type of high-voltage connectors for wiring connections that use high-voltage-compatible coaxial cable-type wires with thicker insulation coating for enhanced voltage resistance. For example, the high-voltage coaxial connectors used in the high-precision detectors of Hisawa Giken Co., Ltd. were made for a U.S. research institute. There are custom-made high-voltage coaxial connectors used in high-precision detectors, and to ensure high reliability in high-voltage wiring systems, the necessary cable connections are made with these high-voltage coaxial connectors.

Coaxial cables are a type of covered wire used in telecommunications, with a cross-section resembling many layers of concentric circles, and are mainly used as high-frequency signal transmission cables for radio communication equipment, broadcasting equipment, network equipment, electronic measuring instruments, etc. High-voltage coaxial connectors are used for high-voltage applications. High-voltage coaxial connectors are used for high-voltage applications.

What is a Resolver?

A resolver is a type of encoder or a sensor for measuring rotation angle.

Among devices that detect the angle of rotation, the resolver reads changes in the magnetic field by electromagnetic induction to detect the angle of rotation, applied to the rotating equipment in which the resolver is mounted.

Uses of Resolvers

Resolvers are mainly used in industrial equipment. You will not see them in white goods or commercial facilities. Servo motors are the main target for measuring rotation angles.

For servo motors to operate accurately, it is necessary to detect and provide feedback on the motor’s speed and other parameters.

In recent years, resolvers are sometimes used in electric vehicles.

Principle of Resolvers

The basic principle of resolvers is almost the same as that of a transformer.

Rotation changes the relative position of the primary and secondary cores, causing a misalignment between the primary and secondary. The principle of the resolvers is to detect the angle of rotation by measuring the AC value. For example, when the rotation angle is 0 degrees, the relative positions of the cores do not change, so no input-output voltage shift occurs.

In resolvers, the part that rotates in conjunction with the object is called the rotor, and the part with a built-in coil is called the stator. On the other hand, an oval shape provides twice the output, and a triangle shape provides three times the output.

Thus, the output signal magnification can be controlled by the rotor shape. Resolvers thus have the advantage of being able to withstand use in adverse environments because of their simple structure consisting of a core and coil.

Other Information on Resolvers

1. How to Use Resolvers

Signal output from resolvers is converted to rotational angle and angular velocity by RDC, which stands for Resolvers Digital Converter, which converts them into digital signals that a CPU can process.

RDC can also compensate for manufacturing variations of resolvers when digitizing rotational angle signals. The arithmetic processing performed on servomotors and motors used in automobiles is generally based on PID control. The amount of energy to be given to the motor is determined by comparing the target rotational speed with the rotational angle and angular speed detected by the resolvers.

To improve positioning and control accuracy, the time difference between rotation angle detection and energy amount determination timing must be minimized, but this depends on the upper limit of CPU operating frequency.

2. Future of Resolvers

Resolvers have a simple basic configuration but are expensive. In addition to the cost of components, it is expensive to continue to manufacture resolvers that guarantee high accuracy.

Resolvers have multiple stator windings, and it is important to wind all copper wires uniformly. Any variation in winding will affect the output signal and lead to a decrease in the accuracy of position detection.

In recent years, magnetic sensors have been adopted as an alternative to resolvers. There are various types of magnetic sensors, but most are MR sensors that use the magneto-resistive effect. The magneto-resistive effect is a phenomenon in which electrical resistance changes depending on the strength and direction of an external magnetic field. Magnetic sensors are selected from the following according to the application.

• AMR (Anisotropic magnetoresistance effect) element
• GMR (Giant magnetoresistance effect) devices
• TMR (Tunnel magnetoresistance effect) devices

The advantages of magnetic sensors are that they can be integrated with bearing rings and do not require signal processing circuits, such as RDC.

What Is a Flow Sensor?

A flow sensor is a device that detects the instantaneous flow rate of a fluid, such as a liquid or gas.

Various measurement methods are available, including:

• The impeller method, which determines the flow rate from the number of rotations of the impeller.
• The volume/mass method, suitable for measuring viscous liquids.
• The electromagnetic method, capable of detecting even minute amounts of fluid.

The vortex flow meter has a relatively small pressure drop, making it suitable for measuring a wide range of fluids, including liquids and gases. Due to its ability to detect various fluids with high accuracy, vortex flow meters are expected to become increasingly popular.

Applications of Flow Sensors

Flow sensors find application in the manufacturing process of industrial machinery, consumer product management, and medical institutions. Flow sensors measure the instantaneous flow rate of a liquid or gas, with accuracy varying depending on the product and detection mechanism.

High-precision products, particularly, have applications in industrial machinery to monitor minute changes in fluid levels during manufacturing. Another application is the measurement of lubricating fluids like oil used in transmissions for automotive applications and fluid characteristics in vehicles, as well as the management of air conditioners in consumer products.

Principle of Flow Sensors

Flow sensors employ various detection mechanisms, with the three most common methods being thermistor, Kalman vortex, and MEMS.

1. Thermistor Flow Sensors

In thermistor flow sensors, a heated thermistor is placed in the flow path. As fluid flows through it, heat is absorbed from the thermistor. The rate of increase in resistance due to the reduction of heat in the thermistor correlates with the flow velocity, allowing for flow velocity measurement.

2. Kalman Vortex Flow Sensors

The Kalman vortex flow sensor utilizes fluid oscillation. When a rod-shaped object is placed in the flow, it acts as a vortex generator, producing alternating vortices downstream.

Under specific conditions, this vortex is highly stable, and its frequency is proportional to the flow velocity, enabling flow rate calculation based on frequency evaluation.

3. MEMS Flow Sensors

MEMS flow sensors are primarily used for gases. Since the resistance value’s dependence on flow location is proportional to the fluid’s flow velocity, they can measure flow direction and velocity by processing calculations from the MEMS’s resistance value.

Other Information on Flow Sensors

1. Flow Switches and Pumps

A flow switch, functioning similarly to a flow sensor, is a switch that operates by sensing liquid flow. When the pump runs, liquid flows, and when the pump stops, the flow ceases. Therefore, flow switches detect liquid state changes by turning flow on and off.

In most cases, systems are controlled by monitoring the liquid flow state. As a result, a pump, generating liquid flow, is used together with a flow switch to detect flow. Flow switches and pumps are designed to work as a set, ensuring effective operation.

2. Difference Between a Flow Switch and a Flow Meter

A flow switch detects liquid flow, operating either ON or OFF. In terms of voltage, they are either L (low) or H (high), in terms of microcontroller processing information, they are either 0 or 1, and in terms of display, they have only two states: operating or stopped, and are used for digital operation.

In contrast, a flow meter is an analog device measuring liquid velocity or flow rate. Displayed measurements are continuous, such as liters per minute, and shown as numerical values.

Flow switches operate via a simple detection mechanism, where a float rises with the liquid, switching off when the level reaches a threshold. In contrast, flow meters have various detection methods, including types similar to the float switch, like the differential pressure method. Choosing the most appropriate option depends on the required measurement accuracy and conditions.

What Is a Radiation Detector?

A radiation detector is a device that detects and measures radiation indirectly by using the physical and chemical reactions caused by the interaction of radiation and matter.

Humans cannot sense radiation directly with the five senses. Therefore, detection and measurement are performed using ionization and excitation caused by radiation. For example, ions, free electrons, and electromagnetic waves such as fluorescence are generated, which are converted into electric current signals. Based on this current signal, the radiation dose can be displayed on a meter or made audible as a sound.

There are many other applications, such as detectors based on electron emission, detectors that use heat generation, detectors based on the practical use of neutron material activation, and detectors based on the detection of Cherenkov light.

Uses of Radiation Detectors

Radiation detectors are widely used in radiation decontamination sites, yards, and factories. There are different types of radiation, such as alpha, gamma, beta, and X-rays, and they emit high to low doses. Therefore, the detector itself must be carefully selected according to the situation.

By measuring the air dose rate, it is possible to determine how much radiation is flying around in space. Also, by detecting radiation emitted from the surface of an object, it is possible to determine whether the object is contaminated and to identify the source of contamination. In addition, radiation detectors can be used to measure the level of radiation exposure of a person.

Principle of Radiation Detectors

There are two main types of radiation detectors: those that use the ionizing effect of radiation on gas molecules and those that use the excitation of electrons in materials, mainly solids and liquids.

The former is called a gas detector and the latter a scintillation detector.

1. Gas Detector

In a gas detector, the detector is filled with a gas such as inert gas or air, and when radiation passes through it, the molecules ionize to produce cations and electrons. The ionization of these gas molecules is used to measure the amount of radiation. There are several types of expectation detectors, such as ionization chambers, GM countertube, and proportional countertube.

Ionization Chamber
In an ionization chamber, cations and electrons are attracted to electrodes respectively and converted into electrical signals for measurement. The number of cations and electrons ionized by the energy of the radiation is converted directly into an electrical signal, so the signal intensity is almost proportional to the energy of the radiation. In other words, it is possible to determine the energy of the radiation. The disadvantage, however, is that the sensitivity is low because the ionization is directly observed.

GM counter
In a GM counter, a gas is charged in the same way as in an ionization chamber, but by applying a high voltage between the electrodes, the electrons generated by ionization move at high speed, causing other gas molecules to become ionized. This allows a strong signal to be obtained.

As a result, one pulse is run between the electrodes for each ionization. A strong signal is obtained, but the disadvantage is that no information about the energy of the radiation is obtained because the signal is a pulse.

Proportional counter
When the voltage applied between the electrodes of a detector filled with gas is appropriately adjusted, ionization of other gas molecules occurs following ionization by radiation, producing a strong signal, and a signal proportional to the number of molecules first ionized can also be obtained. The type that measures these conditions is a proportional counter. 

2. Scintillation Detector

Scintillation detectors utilize the effect of radiation on electrons in orbit around an atomic nucleus, which is then excited and transferred to an outer orbital. An example of an instrument is a scintillation survey meter.

A material that has the property of emitting light via excitation by radiation is called a scintillator. Sodium iodide (NaI) crystals are used as solid crystal scintillators. When radiation is absorbed by the scintillator, the atoms become unstable due to electronic excitation and then return to their original stable state. During this process, the atoms emit energy as light.

This weak light (photon) is amplified by a photomultiplier tube and converted into an electric current for measurement. Since the number of photons emitted is proportional to the energy of the radiation, scintillation detectors can determine the energy of the radiation.

Since NaI crystals are hygroscopic, they are sealed to prevent exposure to air. On the other hand, an incident window is provided where the radiation enters the detector. The incident window is made of a very thin metal with a very low atomic number, such as beryllium or aluminum, about 100 μm in thickness.

How to Select Radiation Detectors

When selecting radiation detectors, it is important to check the following items:

1. Type of Radiation

There are different types of radiation: alpha rays, beta rays, neutron rays, gamma rays, and X-rays. The structure and principle of radiation detectors determine the type of radiation that can be detected and the expected sensitivity, so it is important to select a detector with an understanding of these factors. 

2. Displayed Value

The selection of a detector should be based on the suitability of the displayed value (whether it is a simple count or a 1 cm dose equivalent, etc.) for the intended use. 

3. Radiation Permeability

Since radiation must reach the site of ionization (gas or solid scintillator) to be detected, understanding radiation permeability allows for confident operation. For example, NaI scintillation survey meters are for gamma and X-ray measurements. This is because they cannot detect radiation that cannot penetrate the thin metal window (alpha and beta rays). After all, they must be sealed around a scintillator that is hygroscopic.

Some GM counters are capable of measuring beta radiation, while others are not. The type that can measure beta rays is the one with a large window and a very thin mica window. Beta rays can pass through this mica window. GM counters that can measure both beta and gamma radiation have a metal cap, but the metal cap must be removed for beta measurement. Beta rays do not penetrate the metal cap.

Other Information on Radiation Detectors

1. Purpose of Radiation Measurement

There are two main purposes of radiation measurement.

1. To measure the radiation dose specific to a radiation field, such as the type of radiation, its energy, or the number of particles, to control it when handling radiation.
2. To understand the physical, chemical, and biological effects of radiation, or to make effective use of radiation, the absorbed dose is measured by multiplying the radiation dose in a radiation field by a coefficient resulting from the interaction between radiation and matter.

   Radiation safety management is an extension of the latter. To evaluate the effects of radiation on the human body, the effective dose is calculated based on the latter absorbed dose, adding the biological effects of each type of radiation and an evaluation of the sensitivity of the body part receiving the radiation.

2. Scintillation-based High-energy X-ray Detectors

Scintillation detectors using solid scintillator crystals are used to measure high-energy X-rays and even higher-energy gamma rays. The scintillation detector is characterized by its ability to detect X-rays in proportion to their energy since the scintillator efficiently receives and detects X-rays.

This feature is different from gas detectors, which cannot catch high-energy X-rays. In addition, the time from the time the X-rays enter the detector to the time they are converted into an electrical signal and output is very short, making it suitable for measurements when there are many incident X-ray photons. In the research field, position-detecting high-energy X-ray detectors have also been developed, which utilize the advantages of the scintillation type to acquire a two-dimensional image of X-rays.

What Is a Metering Pump?

A metering pump is a device that repeatedly pumps a fixed amount of liquid.

It is suitable for accurate dosing of chemicals and other liquids. Metering pumps are constructed of corrosion-resistant materials because they are required to resist corrosion. Generally, electricity or compressed air is used as The driving force.

Uses of Metering Pumps

Metering pumps are used to pump out a certain amount of liquid.

The following are examples of applications for metering pumps:

• In the manufacturing lines of pharmaceuticals and chemical products
• For chemical injection and sterilization in agriculture and livestock industries
• For adding sterilizing chemicals in water purification plants
• During neutralization in wastewater treatment plants

Mainly used in industry as part of the manufacturing process, they are also widely used in infrastructure facilities such as water purification plants and wastewater treatment plants.

Metering pumps in the medical field require highly accurate liquid volume control, as errors can directly affect human lives.

Principle of Metering Pumps

Metering pumps are broadly classified into reciprocating and rotating mechanisms.

The reciprocating mechanism in a metering pump will pump liquid by reciprocating a piston. Liquid can be pumped as much as the volume of the piston. It has the advantage of pumping liquid at high pressure.

The rotary mechanism in a metering pump will pump liquid by rotating an impeller or the like. It is capable of pumping out liquid as much as the volume of the impeller and casing. The structure is simple and it can handle a wide range of liquids.

Types of Metering Pumps

Various types of metering pumps are used.

1. Plunger Pump

A plunger pump is a type of reciprocating pump in which the plunger, a rod-like piston, moves back and forth. It is capable of continuously pumping a fixed volume of liquid at high pressure. 

2. Piston Pump

A piston pump is a type of reciprocating pump that pumps liquid through the reciprocating motion of a piston. It is characterized by the use of seals and valves on the piston side for pumping liquid. It can be used under high pressure and it has the advantage of high efficiency.

3. Diaphragm Pump

This is a type of reciprocating pump that pumps liquid using a reciprocating motion of an elastic membrane, such as resin. It is characterized by its seal-less feature and it is widely used for transferring chemical solutions.

It has the disadvantage of pulsation, and flow is generated only when the diaphragm operates. For instantaneous high flow rates, the piping diameter must be enlarged to match the peak flow rate. Pulsation flow can be counteracted by introducing an air chamber or accumulator downstream of the pump or by shifting the phase and installing multiple units in parallel.

The flow rate is adjusted by changing the stroke width and frequency. Drive sources vary, but mainly motor-driven and electromagnetic (solenoid) types are used. The former uses an inverter, and the latter uses electronic control to change the stroke rate.

Ultra-compact diaphragm pumps using piezoelectric elements (piezoelectric elements) are called micropumps. They can handle minute flow rates, such as several µL/min.

4. Screw Pump

This is a type of rotary pump that pumps liquid by rotating a threaded rotor inside the pump. It is characterized by extremely low pulsation.

5. Gear Pump

This is a pump in which two gears mesh with each other and pump liquid only as much as the volume of the gears and casing. When the flow rate is high to some extent, pulsation is minimal. Pulsation appears when the flow rate is reduced and the rotation speed decreases. The flow rate is adjusted by controlling the rotation speed with an inverter.

6. Vane Pump

This is a type of rotary pump that pumps liquid only as much as the volume of the impeller-like vane and casing. The vanes can be installed slightly off-center from the center of the pump.

7. Tube Pump

A tube pump is a pump that continuously pushes liquid in a tube by means of multiple rollers attached to a rotating rotor. It has a simple mechanism with high quantitative performance and it is used for pumping liquid for analytical instruments and adding chemicals.

It is capable of pumping a small amount of chemical solution at a few µL/min. The flow rate is adjusted by controlling the number of roller rotations with an inverter. 

8. Syringe Pump

This pump pushes a syringe at a constant speed and can supply minute flow rates with absolutely no pulsation. However, it is a batch process and cannot supply continuously. It is used for medical applications.