月: 2023年7月

What Is a Server?

A server is software or a computer that acts as the main administrative base for computer systems. Administrative controls can be run more efficiently within a server interface There are many types of servers, each with different functions. Every system in its current state cannot operate without a server.

Types of Servers

1. Web Server

A web server is a server that stores information (e.g., HTML and image files) for displaying a typical web site. It is essential to operate a website because it needs to return appropriate information in response to user requests (i.e., clicks on a website).

2. Mail Server

A mail server is used to send and receive e-mail. In most cases, there are two separate servers, one for sending and the other for receiving mail. There are various reasons for the division into two, but the main reason is that the servers perform very different responses.

The outgoing server is responsible for properly sending the user’s input to the receiving server, and the receiving server is responsible for properly receiving the content sent by the other outgoing server. The outgoing server is called SMTP (Simple Mail Transfer Protocol) and the receiving server is called POP (Post Office Protocol).

3. Database Server

A database server is a server that returns information that has been stored by users, such as text sent and received via web servers and mail servers, and categorizes it appropriately.

4. DNS Server

A DNS (Domain Name System) server is a server that connects your IP address to your domain. Users always have an IP address, and the DNS server associates that IP address with a domain. This conversion makes the URL understandable.

5. FTP Server

FTP (File Transfer Protocol) servers, also known as file transfer protocols, are used primarily by web sites to send and receive files within a site.

In the past, it was only used for sending (sending HTML files to display a web site), but it also retains the ability to receive files if you want to receive them as files (e.g., image files).

6. SSH Server

The SSH (Secure Shell) server is an encryption server. It is used to prevent information leakage by encrypting personal information.

Server Rental

Servers, by their very nature, must be able to hold large amounts of data and operate at high speeds. If a website server is maintained by an individual, it is difficult to determine how much access is expected, so a rental server is generally used to gather the required data.

What Is a Scanner?

A scanner is a device that reads information by scanning an object with light.

Types of Scanners

There are two types of scanners: those that scan two-dimensional information and those that scan three-dimensional information.

Scanners that scan two-dimensional information generally refer to image scanners that scan printed materials as image data. Typical examples are flathead scanners and sheet-fed scanners (ADF scanners, auto-feed scanners), which are widely used to store and manage documents, photographs, and graphics.

Other types of scanners specialize in reading specific image information. These include passport scanners, business card scanners, film scanners that digitize negative and positive photo film, overhead scanners (book scanners, stand scanners) that scan books without cutting them (non-destructive self-catering), and pen scanners that convert text in books into text data. Barcode scanners (barcode readers) that read barcode information such as QR codes are also a type of image scanner.

Scanners that scan three-dimensional information are broadly defined as 3D scanners, and are used to read the physical shape of three-dimensional objects. Non-contact 3D scanners, which are widely used in industry, can be broadly classified into optical scanners and CT scanners.

Optical scanners are suitable for capturing data on the geometry of parts that are clearly visible from the outside. They are used for designing, dimensioning, and inspecting parts in the automotive, aerospace, defense, and manufacturing industries, as well as for surveying topography and large structures in the civil and construction industries. During optical scanning, the light that is irradiated onto the object can be either laser or patterned light.

CT scanners can nondestructively read the internal shape of an object based on the amount of radiation transmitted, and are widely used in the medical field as well as for the inspection of defective parts inside products.

Storage and Management of Scan Data

Conventionally, scanner data has been stored and managed on a PC connected to the scanner. Today, however, network scanners are widely used to store and distribute data without the need to operate a PC by connecting the scanner itself directly to a network.

What Are Drive Mechanism Components?

Drive specifically refers to the motion of rotating a motor and transmitting it as power to rotate a conveyor.

In addition to rotation, it can also convert rotational motion into linear motion and vice versa. A familiar example is the automobile. The rotation of the engine of an automobile is transmitted to gears to rotate the tires and convert them into forward or backward motion, which is also driving.

In this article, the drive mechanism is referred to as the drive mechanism and the parts that drive it are referred to as the drive components.

Types of Driving Components

Since the nature of the drive mechanism varies greatly depending on the different drive components, we will first introduce some typical drive components.

1. Belt

A belt is a component that transmits power using frictional force. Types of belts include flat belts, which are often used for conveyors and other transportation, timing belts, which excel in positioning accuracy, and V-belts, which are suitable for high-speed rotation.

2. Gears

Gears are parts that transmit power by meshing teeth made up of peaks and troughs. Types of gears include spur gears with parallel teeth cut into a cylinder, racks with teeth cut into a bar-shaped object, and bevel gears with teeth cut at an angle like an umbrella.

3. Cam

There are plate cams, in which a disk with a mixture of curves is attached to a rotating shaft, and cylindrical cams, in which a groove is cut in a cylinder.

Types of Drive Mechanisms

The following types of drive mechanisms are available:

1. Belt Mechanism (Chain Mechanism)

This mechanism uses a belt (or chain) to transmit rotation and change the speed or torque to make another rotation. It is used to rotate a cutting tool or shaft, or to transport objects.

2. Gear Mechanism

This mechanism uses gears to transmit rotation, change the speed or torque by changing the gear ratio of the gears, change the direction of rotation by using bevel gears, or convert rotational motion to linear motion by using racks.

3. Cam Mechanism

A cam mechanism transmits rotation and converts it into reciprocating or oscillating motion, or conversely converts reciprocating motion into rotational motion.

In an automobile engine, the reciprocating motion of the piston caused by the explosion of gasoline is transmitted to the crankshaft, which is a cam shaft, and converted into rotational motion.

What Are Surge Countermeasures?

Surge countermeasures are measures taken to prevent circuit breakage when a surge occurs.

While the term surge is commonly associated with sudden rises or spikes in stock prices or prices, in industrial applications, it usually refers to a sudden rise or spike in voltage or current. Surge countermeasures are taken by using surge countermeasure components, which are often referred to as surge absorbers or surge protectors.

There are two main types of surge protection devices: semiconductors and discharge tubes. A typical semiconductor type device is the varistor (ZnO), which derives its name from variable and resistor. Functionally, a varistor is a non-linear resistive element whose resistance changes in response to voltage.

A varistor can be seen as an element that starts the sudden flow of current when a certain voltage is applied. Additionally, there are three semiconductor types: the diode type, which uses a PN junction, and the thyristor type. On the other hand, the discharge tube type are known as arresters (lightning arresters), and they can further be categorized as gap arresters and micro-gap types. The gas-filled discharge tube type is called a gas arrester or gas discharge tube (GDT).

Types of Surge Countermeasures

The surge countermeasures required depends on the type of surge. Surge types can be roughly classified into lightning surge, open/close surge, load dump, and ESD (electrostatic discharge). Open/close surges are caused by the back electromotive force of the coil when the current is suddenly interrupted by a switch. Load dumps, on the other hand, are large surges that occur in automobiles due to battery disconnection.

Examples of Surge Countermeasures

A typical surge countermeasure using a varistor, a semiconductor device, is to connect it in parallel with the protected circuit so that current will flow to the varistor when a surge voltage above a certain level is applied, thereby protecting the protected circuit side. In other words, it is a protection circuit by forming a bypass circuit.

The discharge tube type is said to be more durable than the varistor type, but it is difficult to use the discharge tube type by itself because the discharge tube phenomenon known as continuous current can cause electricity to continue flowing.

What Are Electromagnetic Countermeasures?

Electromagnetic Countermeasures are measures taken to prevent effects of electromagnetic radiation.

Electromagnetic waves are waves that travel through space where electricity flows, where radio waves fly, and where magnetic fields are generated, interacting with each other.

Electromagnetic waves are divided into ionizing and non-ionizing radiation. The boundary between them is 3000 THz, and ionizing radiation is what is usually referred to as radiation. The frequency range of electromagnetic waves covered by guidelines is from 10 kHz to 300 GHz. The lower and higher frequencies are divided into two categories: low frequency and high frequency.

Since the properties of electromagnetic countermeasures differ depending on the frequency, classification by frequency and countermeasures are necessary. Examples of low-frequency waves are power lines and electrical appliances, which operates at frequencies of is 50~60 Hz and wavelengths of 5000~6000 km. Examples of high-frequency waves include cell phones and microwave ovens, which have frequencies ranging from 800 MHz to 3 GHz and wavelengths from 10 to 40 cm. Electromagnetic waves are measured in terms of power density (mW/cm) and absorbed rate (SAR) (W/kg).

In terms of magnetic field strength, the global average of the geomagnetic field is about 46 μT. The World Health Organization (WHO) states that magnetic fields of 500 μT or less are not considered to have any biological effects. 

Guidelines for electric and magnetic fields have been established by organizations such as the WHO and the International Commission on Non-Ionizing Radiation Protection (ICNIRP),. Electromagnetic countermeasures are achieved by absorbing, shielding, and attenuating outgoing and incoming electromagnetic waves.

Types of Electromagnetic Countermeasures

Not all frequencies of electromagnetic waves can be shielded, particularly at low frequencies.

Various types of electromagnetic countermeasures are used. Ferrite cores, capacitors, and common mode choke coils are used as filtering components to attenuate electromagnetic noise, while conductive tape, metal mesh, and shielding gaskets are used to shield incoming and outgoing electromagnetic waves.

In addition, electromagnetic shielding for the housings of home appliances and other products involves the application of metallic materials, electroless shield plating, vacuum deposition, coating with conductive paints, and the attachment of conductive fibers. Aprons made of conductive fibers are commercially available as a method to shield electromagnetic waves to the human body.

Principle of Electromagnetic Shielding

The principle of electromagnetic shielding is to attenuate electromagnetic wave energy based on the three properties of reflection, absorption, and multiple reflection of electromagnetic waves. Attenuation minimizes the adverse effects on the human body and equipment. Shielding performance is usually expressed in decibels, which is the logarithm (log) of the electric field strength after shielding / electric field strength before shielding or the magnetic field strength after shielding / magnetic field strength before shielding multiplied by 20 (in dB).

What Is a Controller?

A controller is a component of a machine or system. It is a generic term for a device that decodes commands, sends signals to other devices, and controls their operation.

Types of Controllers

A control panel is a set of devices used to control a machine or system using electrical signals. It consists of human-operated parts such as switches and buttons, parts that turn power on and off such as breakers, relays, and timers, inverters and servo amplifiers that are control units, and sequencers (PLC) and microcontrollers (8-bit and 32-bit microcontrollers) that give commands. The control panel circuitry can be divided into two main categories: control circuits and power circuits.

The control circuit receives input signals from the operation panel or switches and operates the control unit, such as an inverter, according to the signals. On the other hand, the power circuit sends electric signals to the power unit through the inverter to activate it. There are various types of power units that receive signals, and the name of the control unit differs according to the type.

For example, there are motor controllers, sensor controllers, safety controllers, motion controllers, robot controllers, thermo controllers, LCD controllers, and more that control the operation of all types of motors.

Inverter power modulation methods include PWM, PFM, and PAM, with the PWM method being widely used.

Servo Mechanisms

One of the control devices indispensable in industrial fields such as factory automation is a servo mechanism that automatically controls the position, orientation, and posture of an object according to commands.

The servo controller operates the motor through the servo amplifier, while the encoder attached to the motor sends feedback signals to the servo amplifier. High-precision control is achieved by controlling the motor so that there is no error between the feedback signal and the command issued by the controller.

What Is a Transistor?

A transistor is a semiconductor device used in electronic circuits to amplify electrical signals and to control the flow of electricity.

Transistors are used in various electronic devices. Applications that utilize the amplifying action include audio amplifiers and sensor detection circuits. Applications that utilize the switching action include logic circuits that make up integrated circuits and rectifier circuits for power supplies.

The structure of a transistor is a combination of n-type and p-type semiconductors. They are generally fabricated on silicon (Si) substrates, although compound semiconductors such as SiGe, GaAs, SiC, and GaN may also be used depending on the application.

How Transistors Work

A transistor is a three-terminal device consisting of a thin p-type semiconductor base sandwiched between an n-type semiconductor collector and emitter. This is known as an NPN-type transistor. There is also a PNP-type transistor, in which an n-type semiconductor is sandwiched between a p-type semiconductor. These NPN and PNP types can be combined to make electronic circuits with a various functionalities.

In the case of a PNP-type transistor, the voltage polarity and the direction of the current are reversed. When using an NPN-type transistor, a positive voltage is applied to the base and collector with respect to the emitter. As a result, a current tens to hundreds of times larger than the current flowing in the base will flow in the collector. In other words, the output of the collector current can be controlled by the input of the base current, providing amplification and switching effects.

The ratio of the base current to the collector current is called the current amplification factor, hFE, and is one of the important performance indicators of a transistor.

Types of Transistors

There are several types of transistors based on their structure. Transistors can be broadly classified into two categories: bipolar transistors and unipolar transistors.

The term bipolar means bi-polar because it involves electrons and holes to conduct an electric current. On the other hand, unipolar transistors are named as such because either electrons or holes are involved to conduct current.

1. Bipolar Transistor (BJT)

Bipolar transistors are made from a combination of P-type and N-type semiconductors, with either NPN or PNP junctions. The term transistor simply refers to a bipolar transistor, while an NPN or PNP transistor is called a BJT.

2. Phototransistor

A type of transistor in which the collector current can be controlled by incident light. It can take out a larger photocurrent compared to photodiode.

They should be selected appropriately according to the application.

3. Field Effect Transistor (FET)

While transistors control collector current by varying the base current, field-effect transistors control current by voltage.

Since transistors are controlled by voltage, they require less drive power and can be easily driven at high speeds compared to BJTs. On the other hand, they are inferior in terms of high withstand voltage and high current.

FETs also include junction FETs (JFETs) and metal oxide semiconductor FETs (MOSFETs), each of which has an N-channel type and a P-channel type. Transistors consume a lot of power and generate a lot of heat, so they cannot be used in dense circuits.

Unlike transistors, field-effect transistors consume less power and can be made smaller, as such are widely used in integrated circuits such as ICs and LSIs.

4. Insulated Gate Bipolar Transistor (IGBT)

IGBTs are one of the power transistors used in high-power applications, and their structure facilitates high current and high withstand voltage.

Transistor Operation

Transistors come in NPN and PNP types and are semiconductor devices with three electrodes: base, collector, and emitter.

When the positive electrode of a dry cell battery is connected to the base and the negative electrode to the emitter, electrons flow from the emitter into the base. Some of these electrons combine with holes in the base, while the remaining electrons flow into the junction surface of the base and collector. The current flowing from the base to the emitter is called the base current, while the current flowing from the collector to the emitter is called the collector current. The collector current is much larger than the base current, and a small change in the base current causes a large change in the collector current. This is called the amplifying effect of the transistor.

What Is a Cable?

A cable is an electric wire covered with an insulator and a protective coating.

Generally, an electric wire is a bare wire that consist only of conductors that conduct electricity, and an insulated wire that consists of a bare wire covered with an insulator. Cables are composed of one to several insulated wires covered with an outer sheath, providing safety and durability. Copper and aluminum are mainly used as conductors, while polyvinyl chloride and polyethylene are mainly used as insulators.

Types of Cables

Cables come in a wide variety of types, depending on their performance in terms of allowable voltage and current.

1. VCT Cable

VCT stands for Vinyl Cabtyre Cable. It is a cable with vinyl insulation and outer sheath, mainly used for voltages of 600 V AC or less and 750 V DC or less. It has excellent flexibility, water resistance, and heat resistance, making it suitable for mobile cable applications. Cables intended for use at 300 V AC or lower are called VCTF cables.

2. VVF Cable

VVF cables have a simple flat (F) construction with a vinyl (V) sheath covering the outside of the vinyl (V) jacket. VVF cables with a voltage of 600 V or less are widely used for low-voltage indoor wiring, especially for outlets and lighting up to approximately 15 A. VVF cables with a round shape are called VVRF cables. VVR cables with a round shape are also available.

3. EM-EF Cable

An EM-EF cable is a VVF cable in which the insulation and sheath materials are changed from polyvinyl chloride to polyethylene. It is also referred to as an eco-cable. Dioxin and halogen gas emissions during incineration are suppressed, enabling a reduction in environmental load.

4. IV Wire

An insulated wire used for indoor wiring, suitable for electrical equipment of 600 V or less, grounding wires, and crossing wires to power outlets.

5. CV Cable

CV cables have a structure in which the conductor is covered with cross-linked polyethylene and then covered with a vinyl sheath. CV cables are mainly used as power cables. CVD cables consist of two conductors, CVT cables consist of three conductors, and CVQ cables consist of four conductors twisted together.

6. Robot Cables

These cables are specialized for industrial robots. Performance such as bendability and twistability are required. Cables with a variety of superior resistance have been developed to cope with harsh environments.

Applications of Cables

1. Power Cables

Electric power cables are used to transmit electric power. Electric cables used for transmitting electricity from power plants to substations are called transmission cables, while those used to distribute electricity from substations to factories and homes are known as distribution cables. Those used to connect electricity to machinery, lighting, and other equipment are simply called wiring.

2. Cables for Industrial Machinery

These cables are used in home appliances and industrial electrical equipment. They are also used for extension cords, power cords, and wiring between communication devices. High-quality cables are used for their flexibility, heat resistance, flame retardance, water resistance, and safety.

3. Communication Cables

These cables are used for transmitting data and are used in applications such as internet lines. They convert audio, video, and other data into electrical and optical signals, and transmit and receive signals between devices. Fiber-optic cables and coaxial cables are used.