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What Is an Optical Sensor?

An optical sensor, also called a light-receiving element, is also a semiconductor device. It is one of the auxiliary devices that detects various light properties by converting them into electrical signals and is an accessory device that makes up a machine. The technology of optical sensing is used as a method of sensing light. And there are various types of light sensors for all kinds of situations. A wide range of sensors have been developed, from those that detect whether a light object is within a specified value and pass if it is ON and fail if it is OFF, to types that provide notification and highly sensitive sensors that can detect single photons.

Optical sensor is also used in motion sensors for automatic doors. The sensor’s response is fast, so there is no extra time lag. In addition, because they operate by detecting light, they do not require contact with people or objects, and they do not lead to contamination of the objects they detect. Therefore, the sensor can be used with peace of mind. For these reasons, an optical sensor is used in industrial and consumer applications.

Light includes visible light and invisible light, such as ultraviolet and infrared rays. Therefore, when selecting an optical sensor, it is necessary to choose a sensor that is appropriate for the wavelength.

There are two types of light sensors: those using semiconductors such as photodiodes and those using photomultiplier tubes.

Uses of Optical Sensors

In recent years, the automation of devices in our daily lives has been increasing, and the applications of optical sensors are expanding. Typical examples are remote controls for TVs and audio equipment. These remote controls move in response to infrared rays, so optical sensors for infrared rays are used. They are also used in camera autofocus and image sensors. Other light sensors are also used in washbasin faucets, which automatically switch on and off when they detect a person’s hand.

Once you step out of your house, light sensors are used everywhere in our daily lives.

In automated teller machines (ATMs), optical sensors are used for “card detection,” “bill detection,” and “internal mechanism detection.” In ticket machines, they are used for “coin detection,” “ticket detection,” and “bill detection.” A motion sensor is used to turn on the lighting when someone enters the restroom and to turn off the lighting when no one is in the restroom, contributing to energy saving.

Optical sensors are also used to test the sugar content of fruits, and demand is increasing because they can measure sugar content without damaging the fruit. Sugar content can also be measured by applying the principle that the more sugar and acid components dissolved in fruit juice, the greater the refractive index of light.

They have also been applied to astronomy. In the past, astronomical images were recorded on photographic dry plates, but since the 1990s, charge-coupled devices (CCDs) have been adopted.

Optical Sensors Technology

In recent years, optical sensor technology has made remarkable progress. In the industrial field, nondestructive testing is an inspection method that can examine the status of an object without destroying it. In this inspection method, an object is exposed to radiation or ultrasonic waves to determine the degree of damage without destroying the object. Optical sensors employ a method called near-infrared spectroscopy, which is similar to this type of inspection method. Near-infrared spectroscopy is used in near-infrared spectroscopic sensors and is a mechanism that does not affect the object being observed. Infrared rays are classified into “near-infrared rays,” “mid-infrared rays,” and “far-infrared rays,” of which near-infrared spectral sensors handle near-infrared rays.

Near-infrared spectroscopic sensors can observe a wide range of materials, from inorganic materials to organic materials. For example, they are used in conjunction with machine learning to check the deterioration of concrete in inorganic materials, and in organic materials to observe the amount of fat in the bodies of people and fish.

In this way, the technology of optical sensors is still evolving, not only in one field but also by incorporating additional technologies.

Principle of Optical Sensors

There are many detection methods for optical sensors. The two main types are the transmission type and the retro-reflection type. The transmissive type requires a light-emitting projector and a light-receiving receiver and reacts when there is an obstruction between them. In the retro-reflective type, the projector and receiver are integrated into a single unit, and the light emitted from the projector is detected when it is interrupted by a reflector bouncing back.

In principle, there are also two types of sensors, one using the internal photoelectric effect and the other using the external photoelectric effect.

Internal Photoelectric Effect

This type of sensor uses semiconductors, as typified by photodiodes, and utilizes the photovoltaic or photoconductive effect. Silicon cells cover the visible light range, while germanium cells cover the UV to IR wavelengths. CCDs often used in cameras are in the visible light range.

External Photoelectric Effect

When light is irradiated, electrons are ejected from the cathode and collected on the anode for amplification and detection. Sensors using photomultiplier tubes can detect a wide range from the vacuum ultraviolet region to 1700㎛. Sensors using phototubes can also detect from ultraviolet light to visible light.

Features of Optical Sensors Products

Optical sensor products are available in the following types, which are designed to match the detection target and have features in the optical path.

1. Transmissive Photo Sensor

The light emitted from the light-emitting element has a U-shaped structure with both elements facing each other so that light emitted from the light-emitting element hits the light-receiving element with a certain distance between them. The light emitted from the light-emitting element is measured at the output of the light-receiving element, which changes depending on the obstruction. 

2. Separate Photo Sensor

The light emitting element and the light receiving element are separated in a package, and the distance between the long sensors can be realized to allow any desired setting.

3. Reflective Photo Sensor

Light emitting and light receiving elements are aligned in the same direction or mounted at a certain angle. Light from the light-emitting element is shone on a certain detectable object, and the light reflected from it is measured by the light-receiving element.

4. Prism Photo Sensor

Light emitting and light receiving elements are aligned in the same direction and mounted on a prism between the light emitting and light receiving elements to make measurements.

5. Actuator Photo Sensor

By combining a transmissive photo sensor with an actuator (lever) that rotates, the sensor is shut off by the lever to perform mechanical discrimination.

What Is a PCB?

PCB is essential components for electrical engineering.

It is possible to fabricate electronic circuits by placing transistors, resistors, and other components on a mainly copper wiring pattern on the surface of an insulator (plastic) and soldering them together. PCB is used in almost all electronic devices (TVs, PCs, smartphones, home appliances), and the electronic circuits built into devices are operated by PCB.

Japan was the first country in the world to obtain a patent for PCB around 1936, and the development of the technology has been progressing. As a result, Japan was the world’s largest producer in terms of production value around 1990. In recent years, production of electronic devices has shifted to China and Asia, and large quantities are produced in China and Asia.

Uses of PCBs

PCBs are used as wiring boards for PCs, televisions, and electrical equipment as well as for electronic construction.

The PCBs for these particularly precise electrical devices already have the necessary circuit patterns formed on the board itself, and electronic circuits are completed simply by placing components on them. For even higher density, there are also multilayer boards with multiple layers of circuits on a single board, which are used in electronic equipment such as PCs and smartphones.

There are also many types of materials and hundreds of varieties, depending on the application. Generally, rigid materials are the main materials used, but in recent years, flexible materials (films) are increasingly being used for smartphones and other mobile applications, with many soft flexible substrates being used.

Printed Circuit Board Manufacturing Methods

PCBs are made by drilling small holes in an insulating board and plating the holes with copper or other materials. (called through holes or via holes). By soldering electronic components and wires to the small holes, a circuit can be built by allowing electricity to flow through them. In the case of a multilayer board, signals in the board are connected to other layers through holes and via holes.

PCBs can be single-sided, double-sided, or multilayered. The more layers there are, the more circuits can be built, which saves space.

Materials Used

For home appliances (refrigerators, washing machines), paper phenol substrates made of paper impregnated with phenol resin are the main materials used as substrates for PCBs. For PCs, smart phones, automobiles, measuring equipment, etc., where reliability is required, glass epoxy substrates (glass cloth impregnated with epoxy resin) are used.

Aluminum substrates with good heat dissipation are sometimes used where heat dissipation is required. Recently, demand for these substrates has been increasing due to the trend toward EVs, which require higher current.

Flexible substrates made of thin polyimide or polyester film have also emerged. While flexible substrates have low mechanical strength, they are flexible and can be bent. The materials used for these substrates are required to be flame-retardant (i.e., they do not burn easily even if set on fire). For this reason, halogen-based substances are used, and some customers require halogen-free materials for environmental reasons.

In recent years, circuit patterning methods have become more automated, and products are being developed to accommodate smaller size and higher density.

Structure of PCBs

There are several types of PCBs, each with a different structure, material, etc., depending on the purpose.

Single-sided substrate

A substrate with copper foil only on the patterned side. Only relatively simple patterns can be realized. It is the cheapest type of printed circuit board to manufacture and is the most commonly used type for self-made PCBs.

Double-sided PCBs

PCBs with copper foil on both the front and back sides. Patterns can be drawn on the front and back sides, and more complex patterns can be realized than on a single-sided board. Although it is a bit more advanced, it is also possible to make it yourself. Be careful of pattern misalignment between the front and back sides. Solid ground pattern boards also require through holes.

Multilayer Substrate

Used for complex patterns that cannot be realized with double-sided boards (computer boards, etc.) or when patterns need to be stacked due to board size restrictions (cellular phones, portable audio equipment, etc.). Multilayer substrates with up to 8 layers are used. For boards that require mass production, it is necessary to combine equipment costing hundreds of millions of yen per unit to manufacture several hundred thousand boards per month, making it an equipment industry.

Materials of PCBs

There are several types of printed circuit board materials, each with different properties. Select the one that matches your purpose.

Paper Phenol Substrate

Paper is used as the base material, and the adhesive resin is phenolic resin. Also called “Bake substrate” or “Bakelite.” It has been used for a long time. It is inexpensive and easy to process, but the substrate easily warps and has poor heat resistance and moisture absorption. It also has poor insulation resistance and high-frequency characteristics, and through-holes cannot be formed.

Paper Epoxy Substrate

This substrate uses paper as the base material and epoxy resin as the adhesive resin. It has characteristics intermediate between paper phenol substrate and glass epoxy substrate. It is made as a single-sided substrate. It has superior heat resistance, moisture absorption, and electrical characteristics compared to paper phenol substrates, but is inferior to glass epoxy substrates.

Glass Epoxy Substrate

This is a printed circuit board manufactured by glass fiber containing epoxy resin. Currently, the most widely used type, most multilayer boards are glass epoxy boards, which are used in a wide range of applications, from thin boards as thin as 0.2 mm to boards up to 2.4 mm in thickness for power equipment, motherboards, etc. They have low dimensional change and excellent durability. It also has good electrical and mechanical properties. However, workability is poor, and special tools are required. Although the cost is higher, functionality is improved.

As described above, there are various types of PCBs, and various materials are used. Design rules differ greatly depending on the type of printed circuit board, so please contact a specialized manufacturer if you have any problems.

What Is a Pin Header?

A pin header is a terminal that is attached to a printed circuit board. An example of usage is to attach a pin header to a breadboard, connect a PICkit, and write programs to the PIC microcontroller.

Terminals are plated with gold or tin. They are often long and narrow, with as many as 40 pins in a row that can be removed one at a time, often with cutters or nippers. If the diameter of the pin header does not match, it will not fit into the holes on the board, so be careful not to get the size wrong.

Uses of Pin Headers

Pin headers are attached to boards such as breadboards and universal boards to facilitate signal input and external connections. Although most commonly used for wire-to-wire connections, they are also used as connectors for circuit switching.

The common 2.54mm pitch type is often used, but there are variations in size and length, and one side is bent into an L shape.

They are used for internal connections in a variety of electronic devices such as in-vehicle controls, industrial equipment, computers, communication equipment, medical equipment, storage devices, and home appliances.

Principle of Pin Headers

It is made up of a pin, which is a conductor, and a housing, which is an insulator and serves to connect circuits. These connectors are available in male or male-female types on both sides. The male-male type has pins on both ends and can be attached to a board. Breadboards can be used by simply plugging them in, while universal boards require soldering.

The material is brass, which is either tin-plated or gold-plated. Gold plating is more durable and effective in preventing rust. The operating temperature range is -40°C to 105°C. Single-row or double-row types are available, depending on the application. The rated current and voltage must not be exceeded.

Pin headers that connect boards should be soldered on both ends. They can also be used for flexible boards by using a reinforcing plate. A pin head may also be used to serve as a mounting connection between a flexible board and a rigid board. Female connectors may also be used to enable connection and disconnection.

What Is a Varistor?

A varistor is a semiconductor device with two electrodes whose resistance changes depending on the applied voltage.

The term varistor is derived from the combination of “variable” and “resistor,” meaning “variable resistance.” For this reason, it is sometimes called a non-direct resistance or a voltage-dependent resistance.

It is characterized by the fact that voltage and current are not proportional. When the voltage applied to the Varistor is low, the resistance is high, and when the voltage is high, the resistance is low.

Uses of Varistors

Varistors vary in resistance according to voltage. This characteristic can be used to protect IC elements from static electricity or to protect electronic equipment from lightning surges.

If an abnormal voltage is applied to an element, such as an IC or an electronic device, it may lead to malfunction or destruction. In addition, when a high voltage is applied to a varistor, the resistance of the Varistor becomes low. This allows current to flow through the circuit more easily, and the voltage drop in the line impedance can reduce the load on the electronic equipment. Other uses of varistors include prevention of electrostatic discharge and shattering.

1. Prevention of Static Electricity Discharge

Electronic devices with external interface terminals, such as cell phones, music players, and USB devices, which are used in everyday life, are difficult to shield from static electricity and require the use of components to prevent static electricity. This is because the technological sophistication and difficulty of manufacturing these devices makes them susceptible to electrostatic discharge, which can easily destroy them.

Until now, the method of preventing static electricity has been to use Zener diodes, which provide a stable and constant voltage, but the development of small and inexpensive multilayer chip varistors has led to the use of varistors. 

2. Anti-Dispersion

Commutator motor is a generic term for electric motors and power devices that have a mechanical commutator and brushes to switch the flowing current according to the rotation phase and to keep the power of the rotating shaft in a constant direction.

One type of commutator motor is a brush DC motor that has a part called a brush through which a direct current flows. The commutator, which rotates intermittently, generates high voltage and sparks, causing the brush to wear out and noise to be generated. Varistors are used to prevent this.

Principle of Varistors

Varistors consist of a zinc oxide-based ceramic semiconductor sandwiched between two electrodes. Varistor characteristics can be expressed as I=KV^α, where I is the current and V is the voltage. where K is a constant specific to the device and α is the voltage non-linearity coefficient (α coefficient).

The voltage non-linearity coefficient is a coefficient that expresses the curvature after the refraction point, which is the point where the resistance transitions from low to high. The equivalent circuit of a Varistor consists of two upside-down Zener diodes connected in parallel with a capacitor.

From this, we can see that the varistor has a capacitor component, which means that the voltage across the varistor is low, and that the varistor has a small amount of capacitance when it has a high resistance.

Up to a certain voltage, the varistor has a structure that does not allow current to flow due to its high resistance, but when a load exceeding a certain voltage is applied, the voltage becomes higher than the resistance, and a large current flows due to the quantum mechanical tunneling effect. Therefore, when a high-voltage load is applied to an element or electronic device, the varistor serves to dissipate static electricity to ground and so on.

Other Information on Varistors

Varistor Characteristics

Varistors have a limited life span. You should select a varistor whose life can be properly determined based on the voltage applied to the varistor, the varistor’s withstand capability, and a linear graph that shows the results of a surge waveform, which defines both the state in which the output is released and the state in which it is short-circuited. If the stipulations are greatly exceeded, the product may be damaged or shattered, leading to injury.

Another similar structure is the Zener diode, but there is a slight difference because it has symmetrical current-voltage characteristics and has no polarity.

What Is a Profile Projector?

A profile projector is a device that projects a magnified image of the object to be measured onto a screen at an accurate magnification, and observes and measures the shape and dimensions from the magnified image.

Since the universal projector is an optical measuring instrument, it enables non-contact measurement and observation of the object to be measured without damaging the object. In addition, since the measurement is made by magnifying and projecting the image on a screen, multiple people can observe the image simultaneously. The advantage of this system is that it is easy to handle.

The most common screen size is 300~500 mm, but there are also some larger products with a screen size of 1,000 mm or more. Universal projectors are still in strong demand today because of their simple structure, low cost, and the fact that they can be installed in any location.

Uses of Profile Projectors

Profile projectors are mainly used in industrial production and quality assurance. They can be used immediately after turning on the power and are convenient for quality checks on the production line because of the magnified projection on the screen.

It is used to observe the contours and measure the dimensions of machined parts, and is also useful for comparative measurements using templates. The main objects to be measured are metal parts and resin molded products, but since it is an optical measuring instrument, it can also be used to observe objects that transmit light, such as living organisms. Some models are equipped with a simple surface observation function, so they can be used in a wide range of situations and fields.

Principle of Profile Projectors

A projector projects an enlarged image on a screen by passing a shadow created by transmitting light through a lens onto the object to be measured. Therefore, the part of the stage where the object to be measured is placed must be transparent and have high transmittance so that light can pass through it, such as glass.

Telecentric optics are used in the optical system for transillumination. The advantage of telecentric optics is that the image is only blurred even when out of focus and does not change in size.

Note that profile projectors use a single lens unit to perform the process from focusing to image formation, so the size and magnification of the lens naturally determines the distance from the focal point to the screen. It should be noted that there is a limit to the size of the screen and equipment.

Other Information on Profile Projectors

 Error Factors With a Profile Projector

Typical error factors when measuring with a profile projector are measurement error and magnification error. Profile projectors are basically used for measurement by visually aligning the edges projected on the screen, so alignment errors caused by visual inspection and distortions caused by the operator’s habits cannot be ignored.

Errors caused by the parallelism of the XY stage and the inclination of the object to be measured, or errors caused by the profile projector itself or the object to be measured not being level, can also be a cause of measurement errors. In addition, due to the measurement principle of the profile projector, the light from the light source to the screen is not parallel.

Therefore, if the mirror mounted inside is tilted, there will be a difference in magnification between the center and the edge of the screen. This is called magnification error, and if the magnification error becomes too large, the reliability of measurement values at points off the center of the optical axis will decrease.

What Is a Flat Printed Circuit (FPC) Connector?

A flat printed circuit (FPC) connector is a type of connector that is a circuit component.

It connects flexible circuit boards called FPCs. They are not usually seen because they are used to connect circuit boards inside devices.

Usage of Flat Printed Circuit (FPC) Connectors

Flat printed circuit (FPC) connectors are mounted on rigid circuit boards inside electronic devices and used to connect FPCs. Examples include automobiles, medical equipment, cellular phones, notebook PCs, LCD TVs, digital cameras, and game devices.

FPCs and FPC connectors contribute greatly to the miniaturization and space saving of electrical appliances. Demand is expected to increase in the future, as electrical appliances and portable devices tend to become even smaller.

Principle of Flat Printed Circuit (FPC) Connectors

FPC connectors consist of a contact part for connecting electrical signals and a housing part for protecting the contact part. This configuration is similar to that of an ordinary connector.

The material of the contact part is metal. A copper surface treated with gold, silver, or tin is used for good conductivity. To avoid corrosion due to contact between different metals, the same type of metal as the surface treatment of the FPC to be connected is often selected.

Resin is used for the housing portion. Since it is soldered on a rigid board, heat-resistant resin is used for the resin. It covers the contact section and protects the metal terminals from deformation and damage. The contact and housing take a structure that locks the FPC once inserted to maintain the gripping fit.

Structure of FPC Connectors

As mentioned above, FPC connectors have a locking mechanism. There are two types of locking mechanisms: ZIF structure and Non-ZIF (N-ZIF, non-ZIF) structure. 

1. ZIF Structure

In the ZIF structure, the FPC inserted into the connector is locked with a lever. When locked, the terminals make contact with each other.

Since less force is required for insertion and friction is reduced, workability and contact problems are less likely to occur even when the number of terminals exceeds several tens of pins. For this reason, it is used in many FPC connectors. 

2. Non-ZIF Structure

In the non-ZIF structure, the FPC is inserted into the spring-loaded terminals in a press-fit manner. Since it is a press-fit, the FPC is locked just by inserting it.

Although it is easy to work with because the connection is completed just by inserting, it is not suitable for a terminal count exceeding several tens of pins because of the risk of damaging the connector itself or the FPC due to increased friction.

Types of FPC Connectors

FPC connectors can be broadly classified into four types: two types based on the direction of FPC connection and two types based on the locking mechanism, resulting in the following four 2×2 combinations.

• Horizontal connection ZIF
• Horizontal connection Non-ZIF
• Vertical connection ZIF
• Vertical connection Non-ZIF

There are two connection directions: horizontal and vertical. In the horizontal connection, the FPC is inserted horizontally with the rigid board. In the vertical connection, the FPC is inserted perpendicular to the rigid board.

There are two types of locking mechanisms: ZIF and Non-ZIF. ZIF uses a locking lever to secure the FPC inserted into the FPC connector, while Non-ZIF has no locking lever and uses a spring-loaded metal contact to press the FPC into the connector.

How to Select an FPC Connector

In addition to the aforementioned items, there are other parameters to consider when selecting an FPC connector. It is important to select a component that matches the intended use and the characteristics of the equipment in which it will be mounted.

1. Terminal-To-Terminal Pitch

The distance from the center of an electrode to the center of the adjacent electrode is called the pitch; it is necessary to select a connector that matches the wiring pitch of the FPC.

2. Thickness of FPC

In order to guarantee the stability of the connection and the electrical connection, it is necessary to select a connector that matches the thickness of the FPC. 

3. Number of Electrodes

The appropriate number of electrodes must be selected according to the circuit design of the rigid board and FPC. 

4. Contact Surface Treatment

From the standpoint of reliability of signal continuity and corrosion protection, connectors should be selected so that the contacts are the same metal as the FPC. 

5. Contact Direction

There are three types of contacts with the FPC: top, bottom, and both sides. The appropriate contact direction should be selected in accordance with the structure of the device to be used. 

6. Signal Type

A dedicated flat printed circuit (FPC) connector must be selected according to the characteristics of the signal to be passed through the FPC, such as high power or high-speed transmission.

What Is a DC/DC Converter?

A DC/DC converter is a power supply device that generates varying DC voltages from a constant DC power source.

A converter that outputs a higher voltage than the input DC voltage is called a boost converter, while a converter that outputs a lower voltage is called a buck converter.

Applications of DC/DC Converters

DC/DC converters are used to provide suitable power supply voltages for some circuits inside electronic equipment.

Generally, electronic equipment operates using commercial power (AC), but electronic circuits require a DC power supply, so the commercial power supply is converted to DC. This power circuit is called an AC/DC converter.

On the other hand, since the optimum operating voltage range for electronic components such as ICs that make up a circuit differs from each other, the appropriate voltage must be supplied to each individual circuit. In such cases, DC/DC converters are used.

Principle of DC/DC Converter

There are two types of DC/DC converters, each with a different principle.

1. Linear Regulator

In a linear regulator, an NPN transistor is inserted between the input and output terminals, and the output voltage is maintained constantly. by controlling the voltage between the collector and emitter of the transistor. The transistor has the collector on the input side and the emitter on the output side. The control circuit detects the difference between the output voltage and the desired voltage.

The basic operation is to control the base current of the transistor and vary the voltage between the collector and emitter to keep the output voltage constant. The control circuit controls the gate voltage. 

2. Switching Regulator

The basic operation of a switching regulator is to install a switching element between the input and output terminals. In addition, switching regulators supply power from the input to the output with the switching element in the ON state until the output voltage reaches the desired voltage, and then turn the switching element OFF when the output voltage reaches the desired voltage.

This operation is repeated at high speed to control the output voltage and to keep it within the desired range. In switching regulator type, DC To DC Converters in combination with an inductor can reverse voltage generated from the inductor at the time of current interruption and can be used for boost operation to obtain a higher voltage than the input voltage.

In addition, a step-up/step-down regulator that can output a constant voltage regardless of the input side voltage, as well as an inverting regulator that creates a negative voltage from a positive voltage, can also be realized.

Types of DC/DC Converters

There are two main types of DC/DC converters: linear regulators and switching regulators.

1. Linear Regulator

An NPN type transistor is inserted between the input and output terminals to control the output voltage so that it is always constant.

The output voltage is lower than the input voltage.
Energy efficiency is poor and heat generation is high due to high transistor losses. 

2. Switching Regulator

A switching element is installed between the input and output terminals, and the current flowing from the input terminal is turned on and off by the switching element to maintain the voltage at the output terminal at a constant level, which has the following advantages:

• Depending on the circuit configuration, it can be used with either a boost converter or a buck converter.
• High energy efficiency and low overall circuit heat generation.

On the other hand, the disadvantages are as follows:

• Switching noise is generated and spike noise or ripple appears on the output.
• The number of components is large and the circuit size is large.

How to Use DC/DC Converters

Linear regulators provide stable voltage output with low noise and are suitable for analog circuits, such as when handling weak signals from various sensors. However, since they generate a large amount of heat, proper heat dissipation design is required. Consideration must be given to dissipate the generated heat to the outside of the device by using heat sinks or fans in combination.

Switching regulators, on the other hand, allow a wide range of output voltage settings and can supply large currents, but they inevitably generate noise, which may require countermeasures. An example of such a countermeasure is to place the device in a shielded case.

However, to prevent noise from penetrating into analog circuits, it may be necessary to separate the power supply itself and ground the DC/DC converter and analog circuits at a common ground level by grounding them at a single point.

Also, although heat generation is relatively low, when outputting a large amount of power, it is necessary to design the device with sufficient attention to heat dissipation inside the device, as is the case with linear regulators.

What Is a Robotic Controller?

The robotic controller has the following principles and functions:

• Determines robot motion.
  Determines the next move of the robot in response to commands from a PLC or other high-level device.
• Calculations and commands
  Calculates the motion of the motors in the robot’s joints and sends commands to the motors.
• Abnormality detection
  Detects abnormalities in the robot and stops it.

Some recent products are equipped with AI, and many robots can determine how to move next time without teaching. Robotic controllers for industrial robots and human-controlled robots are available from robot manufacturers, and specifications differ among manufacturers.

A robotic controller is not compatible with other companies, and a robotic controller from a particular manufacturer cannot operate a robot from another manufacturer.

Other Information on Robotic Controllers

1. Types of TP (teaching pendant)

There are two types of TPs: wired type and wireless type (e.g., tablet type).

Wired Type TP
The wired type is often used for traditional industrial robots. Workers are accustomed to using them at manufacturing sites where existing industrial robots are used, such as automobile manufacturers.

One disadvantage of the wired type is that it may take some time for beginners to master its use. To use this type of controller for beginners, it is necessary to become proficient to some extent by reading manuals or attending robot training sessions, or requesting a dedicated robot SIer to build a system.

Wireless type TP
The wireless type is mainly used for human-controlled robots. One advantage of this type is that it is designed to be relatively easy to use, even for beginners.

Many TPs employ a large touch panel screen and an intuitive operation called direct teaching so that even beginners can use the system immediately. Therefore, it is possible to control the robot by ourselves without hiring a robot SIer.

In addition, the absence of thick cables makes it possible to build a neat robot system.

2. Evolution of Robotic Controllers

Robotic controllers are evolving daily in response to the expansion of robot applications and the growing demand for automation. Here, we discuss the evolution of robotic controllers toward miniaturization and higher functionality.

Miniaturization
In recent years, demand for smaller robots has been increasing for applications such as electronic component assembly. In line with this trend, there is a growing demand for smaller robotic controllers.

Robot manufacturers such as Fujikoshi, Kawasaki Heavy Industries, and Yaskawa Electric have commercialized compact robotic controllers in the 12-15L volume class. These products are more than 70% smaller than conventional models.

Increasing Sophistication
It can be said that robotic controllers are evolving in a direction that allows them to control not only robots but also surrounding machines altogether. For example, some robotic controllers have PLC functions built into them, eliminating the need for an external system control panel to control servo motors, I/O, and other functions.

What Is a Torque Motor?

A torque motor is a type of motor that provides high starting torque, decreasing as rotational speed increases. It operates stably across a broad speed range, making it ideal for rollers and winding devices. Torque motors are particularly effective at low speeds, where high torque is essential for tasks such as winding, where initial low torque and high speed are needed, transitioning to high torque and low speed as the diameter of the wound material increases.

Uses of Torque Motors

Torque motors are integrated into equipment for constant-speed winding of sheet materials like cloth, paper, rubber, or linear materials such as metal wire, cable, or thread. They are utilized in applications requiring constant tension, including feed rolls, compensation for roll tension loss, small cranes, belt conveyor drives, as well as for tightening valves and screws, and automating door movements.

Principle of Torque Motors

The RPM-torque characteristic curve of a torque motor, unlike other motors, steadily decreases, showcasing a droop characteristic. This allows the torque to decrease with increasing rotational speed to maintain balance with the load. By adjusting the applied voltage, this droop characteristic can be tuned, making torque motors adaptable for applications requiring static torque for constant angular velocity operations. They are also efficient for tasks needing frequent starts and stops due to their high starting torque and low starting current requirement.

Other Information on Torque Motors

How Torque Motors Are Used as Brakes

Torque motors can also function as brakes to maintain constant tension in unwinding applications, utilizing their braking characteristics in two main ways:

1. Reverse-Phase Braking
Utilizes the torque generated when the motor rotates against the direction of the applied AC voltage’s magnetic field. This braking force is effective from zero rotation speed, making it suitable for maintaining tension even when the motor is stopped.

2. Eddy Current Brake
Employs the braking force generated by the eddy currents when a DC voltage is applied, working independently of the motor’s rotation direction. The brake force increases with rotation speed, stabilizing at higher speeds, ideal for maintaining tension in both forward and reverse directions at high rotational speeds.

What Is an Impact Tester?

An impact tester is a testing machine used to perform impact tests.

In impact testing, we confirm that the products we use have sufficient strength when subjected to impact, and in the event of breakage, we confirm the type of breakage that occurs. Some of the products we use in our daily lives have components that are used under impact loads or are subjected to impact due to accidental factors. To maintain product safety, it is essential in product development to evaluate the durability and breakage of products under impact loads.

There are two main categories of impact testing. The other is the impact strength of the product itself and how it breaks when subjected to impact.

Most of the tests standards are classified into the former category. In these tests, the amount of distortion, expansion, shrinkage, flatness, surface cracks, etc. are measured when a sample is subjected to impact.

Uses of Impact Testers

Impact testers are used to evaluate whether or not, or to what degree, a product, its components, or its materials have the specified impact strength. Impact Testers are used to verify the impact strength of metal materials and resins, and the strength of industrial products to impact loads.

Smartphones, which are indispensable in our daily lives, are not usually subjected to impact loads. However, it is possible for them to be dropped by accident. Impact Testers are used to confirm that a product will not break even if it is accidentally dropped, and to determine the type of breakage that may occur.

Principles of Impact Testers

There are various impact testers, each of which has its own testing machine. The common principle of the impact tester is that the test specimen and test method are specified to ensure repeatability of the test.

Impact testers apply an impact load to the test object, and it is important that the same conditions are applied when the test is repeated. While the impact test may result in significant plastic deformation or even cracking of the test object, slight differences in the impact load can significantly alter the results.

Variations in the test object itself may also have an effect. Therefore, the test method is defined from the viewpoint of how the same impact load can be repeatedly applied and how the test can be performed with high reproducibility.

Other Information on Impact Testers

Types of Impact Tests

The following three types of impact testing are typical. 

1. Izod Impact Tester
In the Izod impact test, one side of a specimen is fixed and the other side is impacted to measure the impact value. One side of the incised specimen is fixed and impacted with a pendulum-type hammer.

The evaluation is made by the angle at which the hammer impacting the specimen is lifted by inertia. This test method is mainly used to evaluate the toughness and tenacity of materials.

2. Charpy Impact Tester
Charpy impact test is a test to evaluate the brittleness of materials. Fragility refers to brittleness. It is evaluated by fixing both ends of a specimen piece with a cut in the center, applying an impact to the center of the specimen with a fixed force, and measuring the amount of deformation of the specimen at that time and the magnitude of the impact value at the time of failure.

At the time of breakage, the energy absorbed by the specimen at the time of breakage is calculated using the potential energy of the hammer that jumped up upon impact.

3. High Acceleration Impact Tester
High acceleration impact testers are testers that measure the degree to which a product is damaged by an impact by fixing the product to be measured on an impact table and generating a waveform of impact acceleration on the table. It is used for electronic devices such as smartphones and laptop computers.

Other tests include: 

• Plastics – tensile impact strength test
• DuPont drop impact test
• Dart impact test