月: 2023年2月

What Is an SHDSL Modem?

An SHDSL Modem is a transmission device that enables high-speed and stable data transmission over long distances using telephone lines.

In the case of methods such as UTP and optical wiring, huge costs are required when it comes to laying optical fiber cables that extend over several kilometers. SHDSL Modem, on the other hand, is relatively simple and requires only a short construction period, resulting in a low-cost, long-distance transmission network.

Because SHDSL modems can be installed at very low cost, they are very suitable for use in large areas such as factories, airports, and railroads.

Uses for SHDSL Modems

SHDSL Modem is used for existing telephone lines. Since they allow LANs to be extended to locations several kilometers away, they are well suited for installation in facilities that boast extensive grounds. Examples include factory premises, parking lots, campuses, shopping malls, ski resorts, airports, and train stations.

Even if LAN wiring and optical fiber installation would be expensive, network and LAN extension can be done at low cost by using already installed telephone lines. In this way, it is an excellent cost-effective means of using existing facilities as they are.

Principle of SHDSL Modem

The SHDSL system is an xDSL communication standard formulated based on the HDSL system. SHDSL uses two pairs of lines, using the same frequency bandwidth in the uplink and downlink directions.

Because of the use of telephone lines, SHDSL requires a modem to access the Internet, and SHDSL Modems are used for this purpose.

While Ethernet is limited to a maximum distance of 100m, SHDSL and VDSL can extend LANs to several kilometers. In addition, high-speed communication is also possible. Furthermore, the symmetrical nature of SHDSL and VDSL modems enables bi-directional communication at the same speed. VDSL modems can achieve bi-directional maximum speed of 100 Mbps.

Features of SHDSL Modem

SHDSL Modem has the following features:

1. Low Cost

Installation costs are far lower than other methods such as optical fiber. This is because existing premises telephone lines are used, so there is no need for any new wiring work. Compared to other methods that require wiring work and other construction costs, installation costs are lower. 

2. Easy to Install

Another advantage of SHDSL Modem is that installation itself is by far the easiest. Simply install SHDSL Modem on both ends of an existing telephone line. Metal lines (copper or electric wires) can also be used.

However, SHDSL requires that the metal line be an open line. Even in areas where the path from the base station to the user is partially wired with fiber optic cable, SHDSL communication is possible as long as the original copper line is still available. 

3. SHDSL Modem-To-SHDSL Modem Connection Is Possible

SHDSL Modems can be connected point-to-point, that is, one modem to another modem, over a distance of approximately 7km with a 0.4m diameter core wire.

Other types of connections include point-to-multipoint, where multiple SHDSL Modems are connected to a single SHDSL Modem, and ring connections, where Modems are connected to each other in a ring.

Other Information on SHDSL Modems

Bonding Technology

SHDSL Modems can use additional bonding technology to increase speed. Bonding is a technology that bundles multiple lines together. By bundling lines together, speeds can be improved.

Bonding can also improve service continuity by providing redundancy in the event of physical failure of a network interface or failure of the network switch to which it is connected.

What Is an RC Servo Motor?

RC servo motors are compact devices primarily used in radio-controlled (RC) vehicles and various control applications. They allow for precise control in response to specific command values, making them ideal for steering mechanisms and similar tasks.

Uses of RC Servo Motors

Originally, RC servo motors were developed for controlling radio-controlled vehicles. However, their use has broadened to include robot motion control, where precise movements are essential. They offer more accurate control compared to stepping motors, thanks to their internal feedback mechanism. This mechanism adjusts movements based on real-time feedback from an encoder, ensuring precise alignment with commanded values.

Principle of RC Servo Motors

RC servo motors operate by responding to pulse signals, which dictate their rotation position and direction. Typically, these motors require pulses with a cycle of 15 to 20 ms and a width of 0.5 to 2.5 ms. The process of sending commands through pulse width modulation (PWM) aligns the pulse width with the desired motor angle. The servo’s circuit board processes the input command and the potentiometer’s angle measurement, adjusting the DC motor’s voltage via a motor driver to achieve the target position.

Structure of RC Servo Motors

An RC servo motor integrates a DC motor, gear head, drive circuit, and an angle-command type servo controller into a compact package. Typically, they feature three parallel wires for signal input, allowing for movement to any specified angle. These connectors often use a female connector with a 2.54mm pitch.

1. Signal Line

The signal line carries pulse-shaped inputs to control the motor. It’s usually colored white, blue, yellow, or orange. Some models require a pull-up resistor to ensure compatibility with microcontroller signal inputs.

2. Power Supply Line

Comprising two lines, one for the power supply (+) and the other for the ground (GND), the power line is typically red, while the ground line may be black or brown. This color coding helps prevent incorrect connections.

Other Information for RC Servo Motors

1. Potentiometer

In RC servo motors, potentiometers measure rotation or movement as a change in voltage. Connected directly to the servo’s output shaft, they function as displacement sensors, enabling the microcontroller to calculate the motor’s position based on voltage output.

2. PWM

PWM control in RC servo motors can employ the triangular wave comparison method. This method involves comparing a desired sine wave frequency with a triangular carrier wave in an operational amplifier. The comparison dictates the switching control signal’s ON or OFF state, producing the necessary pulse wave for motor control.

What Is a PVC Sheet?

A PVC sheet is a product made of soft polyvinyl chloride (PVC) to which a plasticizer is added and processed into a sheet form. It is used in various applications because of its various advantages such as durability, lightness, and low cost.

PVC sheets are transparent and are used as sheets for vinyl greenhouses for agriculture. PVC sheets are resistant to oxidation by oxygen in the air, but they harden at low temperatures, making them susceptible to cracking.

Characteristics of PVC Sheets

PVC is polyvinyl chloride, commonly known as “vinyl chloride,” which is a synthetic resin. PVC is widely used for its various advantages such as lightweight, low cost, and high durability, etc. The softness of PVC can be controlled by adding plasticizers.  Soft resin containing plasticizers is called “soft PVC” while hard resin without plasticizers is called “hard PVC.

PVC sheets are made of soft PVC processed into a sheet form. Because PVC is easy to color and print, it is used for housing decoration, and because it is transparent and weather-resistant, it is used as a sheet for vinyl greenhouses for agriculture. In addition, conductive PVC sheets printed with conductive carbon are also used.

Manufacturing Process of PVC Sheets

PVC is made by polymerizing a monomer called vinyl chloride. Because the monomer contains chlorine atoms, it exhibits different properties from other resins. It is more flame-resistant than polypropylene and polyethylene, which have only carbon and hydrogen as constituent atoms. PVC sheets are made by adding a plasticizer to the PVC obtained by polymerization, softening it, and then processing it into a thin sheet.

Recently, material recycling has been progressing, where PVC is reused once it has been processed. For example, PVC sheets used in agriculture are cleaned, crushed, and converted into recycled resin for use as flooring material.

There are also chemical recycling, which uses chemical methods to recycle PVC, and thermal recycling, which effectively uses the heat energy generated when PVC is burned.

Durability of PVC Sheets

PVC is more durable than resins such as polypropylene and polyethylene. It is almost impervious to oxidation reactions caused by atmospheric oxygen and can ideally be used semi-permanently.

On the other hand, PVC sheets harden rapidly at low temperatures, making them unbendable, and the hardening may also make them susceptible to cracking. In addition, plasticizers may gradually appear on the surface of the resin, causing it to lose its softness. Other types of organic solvents may dissolve the sheet; if PVC sheets are likely to come in contact with chemicals, it is recommended that their resistance to chemicals be checked beforehand.

What Is a PIN Pad?

A PIN pad (personal identification number pad) is a device used in financial transactions where customers enter their pre-determined PIN for IC card-enabled cash or credit cards. This technology is a staple in modern financial and retail transactions, enhancing security and convenience.

Uses of PIN Pads

PIN pads are primarily utilized in banks and retail point-of-sale (POS) systems, serving as a secure method of customer identification for transactions with IC card-compatible credit or cash cards.

Previously, cash cards relied on magnetic stripes which became vulnerable to fraud. Similarly, credit card transactions based on signature verification posed challenges in instant authentication. The advent of PIN pads and IC cards revolutionized these processes by offering a more secure and efficient means of verification.

Principle of PIN Pads

PIN pads work on the principle of knowledge authentication. When a customer inputs their PIN, the system verifies whether it matches the reference PIN data – a unique identifier pre-registered with the financial institution. This process can be categorized based on where the reference PIN data is stored and how the authentication is performed.

According to ISO 9564, an international standard, authentication can be conducted by the terminal, IC card, or host systems within financial institutions. This standard also covers where reference PIN data is stored, including terminals, IC cards, and host systems.

Offline PIN authentication is performed using only IC cards or terminals, while online PIN authentication involves a host system to verify the entered PIN in real-time.

What Is a PCR Plate?

A PCR plate is a plastic experimental device used as a reaction vessel in PCR (Polymerase Chain Reaction) experiments. Unlike PCR tubes, PCR plates are suited for medium to large-scale experiments due to their capacity to handle a larger number of samples. Available in various sizes and colors, these plates are integral in automated processes.

Uses of PCR Plates

Figure 1. PCR plate and principle of PCR

PCR, a technique for amplifying specific DNA sequences, involves repeated cycles of denaturation, annealing, and elongation. A thermal cycler automates these temperature changes. Selecting the right PCR plates is crucial, depending on the thermal cycler’s specifications and the type of PCR being performed, such as standard, gradient, or real-time PCR/qPCR.

Structure of PCR Plates

Figure 2. Names of the parts of a 96-well PCR plate

PCR plates, typically made from polypropylene, are designed for efficient heat transfer and minimal reaction component absorption. The choice of well color impacts the experiment’s visibility and sensitivity, especially in qPCR.

The production environment for PCR plates is highly controlled to prevent contamination that could interfere with PCR accuracy. The plates come in various sizes and colors, with different skirt styles and deck types to cater to diverse laboratory needs and equipment compatibility.

How to Choose PCR Plates

Figure 3. Examples of PCR plate / Component types

Choosing the right PCR plate involves considering the type of experiment, well color and volume, thermal cycler compatibility, and the need for automation. Transparent wells are ideal for visual checks, while white wells enhance qPCR sensitivity. The well size should match the reaction volume to avoid issues like inadequate heat transfer or sample evaporation.

Plate shape and skirt style should align with the thermal cycler’s specifications and any automation requirements, such as robotic handling or tracking. Plates with strong polycarbonate frames are preferable for automated processes due to their durability under mechanical stress and thermal cycling.

What Is an OPP Film?

OPP (oriented polypropylene) film is a versatile plastic film made by biaxially stretching polypropylene, a widely used plastic. Known for its excellent transparency, rigidity, moisture resistance, and printability, OPP film is a preferred material in various packaging applications. Despite its lower heat sealability and tear resistance, its benefits make it a popular choice over cast polypropylene (CPP) film, which lacks the superior transparency of OPP.

Uses of OPP Films

OPP film’s unique properties make it ideal for:

• Product Packages: Utilized for its protective qualities in retail, enhancing product visibility while ensuring durability during transport and display.
• Food Packages: Chosen for food packaging due to its strength, moisture resistance, and easy-tear features, improving consumer convenience and product freshness.

Principle of OPP Films

OPP film capitalizes on polypropylene’s inherent thermal and mechanical robustness, with biaxial stretching enhancing its tensile strength, thermal stability, and moisture barrier properties. This process not only boosts the film’s physical attributes but also its optical quality, providing a clear and attractive finish for printed materials.

Other Information on OPP Films

How OPP Film Is Manufactured

OPP film production involves biaxially stretching a polypropylene film first longitudinally and then transversely. This simple yet effective method improves the film’s physical and optical properties while maintaining cost-effectiveness by avoiding the need for specialized equipment.

What Is an OPC Server?

An OPC server is an application that facilitates communication and data exchange between various equipment in a factory, playing a crucial role in industrial automation.

OPC, which stands for OLE (Object Linking and Embedding) for Process Control, is a widely adopted industrial communication standard for process control. Developed in 1996 by Microsoft and equipment control manufacturers, the standard is now being standardized by the OPC Foundation.

OPC has significantly improved the interaction between suppliers and users in the field of automation, offering expanded options for equipment control. This has led to increased adoption of OPC by suppliers in their automation applications.

Uses of OPC Servers

In factories, a variety of devices like machine tools, PLCs (Programmable Logic Controllers), and other control devices operate simultaneously. Each device manufacturer provides OPC server software to facilitate access and communication with their respective devices. Additionally, OPC client functions are integrated into various applications for production planning and management.

This setup allows both equipment manufacturers and users to communicate and control devices using the OPC standard, enabling seamless data acquisition and writing, irrespective of individual product specifications.

Principle of OPC Servers

OPC standardization allows for vendor-neutral data communication between devices and OPC servers. These servers, functioning as PC or PPC servers in the field, enable unrestricted communication with PCs, PLCs, and machine tools. This interoperability is maintained even across different vendors, adhering to the specified protocol and commands.

OPC Servers facilitate READ/WRITE operations of production data with connected devices according to the OPC standard.

The following steps outline the communication process:

• STEP-1: The application requests data from the OPC servers.
• STEP-2: The OPC servers retrieve information from the connected equipment.
• STEP-3: The OPC servers transmit the data back to the application.

This system allows the OPC servers to handle READ/WRITE requests, with the connected devices simply responding to these requests.

What Is an NTP Server?

An NTP (Network Time Protocol) server is a dedicated server that synchronizes the time across network devices by sending the current time over the Internet.

Network Time Protocol (NTP) is a protocol for retrieving and correcting time data between servers on a network and providing accurate current time to client PCs. It ensures network devices such as PCs and routers are synchronized in time, preventing problems caused by time discrepancies.

Currently, NTP servers provide extremely accurate time measurements based on atomic clocks, crucial for maintaining network synchronization.

Uses of NTP Servers

NTP servers are utilized by a wide range of devices, from home and office PCs to network equipment. Various organizations also rely on NTP servers, including:

• National and private universities
• Major telecommunications providers
• Major corporations
• Astronomical observation sites, such as the National Astronomical Observatory of Japan
• Independent administrative agencies in the information field

Principle of NTP Servers

The second is defined based on the radiation period of a cesium-133 atom, a method providing the highest precision for time measurement. This definition is the standard unit in the International System of Units (SI). In Japan, the standard time is maintained by the NICT (National Institute of Information and Communications Technology).

Hierarchical Structure of NTP

NTP uses a hierarchical structure, known as Stratum, for load balancing. Stratum 0 refers to the atomic clock, while Stratum 1 consists of servers like NICT’s NTP servers, which receive time from Stratum 0 and distribute it. To avoid overloading Stratum 1 servers, additional layers like Stratum 2 are used, though they may have slightly less accuracy.

Other Information on NTP Servers

1. NTP Servers and Quartz Crystals

Quartz crystals are traditional timekeeping devices, vibrating with a fixed period when voltage is applied. This method, used in PC hardware, deviates by approximately one second per million seconds, leading to synchronization issues in networked computers. NTP servers, obtaining time from atomic clocks, provide a more accurate time to network devices.

2. Major Public NTP Servers

Public NTP servers are available for general use. Notable examples include NICT’s servers (ntp.nict.jp) and Cloudflare’s service. Google also offers public NTP servers based on their atomic clocks, ensuring high accuracy.

3. How to Set Up NTP Servers

Setting up an NTP server varies by OS. For Windows:

• Go to “Date and Time” in the Control Panel.
• Select the “Internet Time” tab.
• Enter the NTP server address in the “Server” field.
• If the OS time display is inaccurate, adjusting the NTP server settings may correct it.

 

 

What Is an MS Connector?

An MS connector is a connector that conforms to the MIL-DTL-5015 standard, which is one of the many MIL (Military Standard = MS) connectors that exist among connectors that are used to connect electric wires or between electric wires and electrical appliances.

This is because MIL-DTL-5015 was the first connector standard established in the history of the U.S. military, and therefore the most widely used military connector standard in the industrial world.

Uses of MS Connectors

MS connectors are used in industrial equipment applications, but they can also prevent wire breakage and momentary disconnection due to vibration and shock, as well as short circuits caused by condensation and high humidity.

They also prevent shorts due to condensation or high humidity. In addition, signal and power wiring can be combined in a single connector, enabling space-saving equipment layouts with high-density multi-cores (up to 128 cores).

On top of that, they are so robust that they will not break even if dropped or bumped a little, and so highly reliable that they can continue to be used without worry even in places where maintenance is extremely difficult.

For this reason, MS connectors are used in a wide variety of fields, including measuring equipment, semiconductor facilities, industrial robots, construction machinery, plants, power plants, mass transit vehicles such as railroads, space equipment applications, outdoor communication equipment, and more.

Principle of MS Connectors

MS connectors are the original U.S. military MIL standard connectors.

Although designed more than 70 years ago, MS connectors are still widely used in today’s high-tech industrial equipment in the 21st century.

The main features and advantages include threaded mating, a sturdy metal housing, a wide array of insert arrangements covering signal to power, and compatibility with a wide range of wire sizes, but the greatest advantage is the worldwide popularity of MS connectors themselves.

MS connectors are said to be the most widespread circular connectors in the world.

Therefore, it is said that even for unidentified industrial equipment imported and exported from abroad, as long as MS connectors are used for the interface, there is almost no need to have trouble obtaining mating connectors.

What Is MOSFET?

MOSFET is one of the semiconductor devices and a type of transistor that is indispensable in electronic devices.

MOS stands for “Metal Oxide Semiconductor” and FET stands for “Field-Effect Transistor.”

MOSFET performs on/off switching and signal amplification operations. One advantage is that they are very fast in operation and are suited for precise control.

Previously, semiconductor devices were dominated by high-polar transistors. However, with the increasing need for smaller, lighter, and more efficient devices, MOSFET has been becoming the mainstream semiconductor device in recent years.

Uses of MOSFET

MOSFETs are used as transistors in electronic circuit configurations for various ICs and LSIs.

Discrete applications include power electronics, sensors, and other industries, as well as power supply systems and inverters. Various LSIs are used in a wide range of applications, including microcontrollers for automobiles and information appliances, portable terminals such as smartphones and tablets, PC memory, and CPUs for various computers.

MOSFETs have become indispensable in recent products because they can be made smaller, lighter, and more integrated.

Principle of MOSFET

MOSFETs have three terminals (electrodes), called “drain,” “gate,” and “source,” respectively. By applying a voltage to the gate electrode, the MOSFET performs on/off switching and amplification operations as a transistor.

There are two types of MOSFET: N-channel (N-Ch) type and P-channel (P-Ch) type.

• N-channel (N-Ch) type
  Current flows by applying a voltage to the gate that is more positive than the source potential.
• P-channel (P-Ch) type
  N-channel (N-Ch) type is often used because it is more convenient in terms of performance and circuitry.

CMOS (Complementary Metal-Oxide-Semiconductor), which is widely used in digital circuits, memory ICs, and sensors, consists of a pair of p-type and n-type MOS transistors. MOSFET has high operating speed and can switch at high speeds.

They are also suitable for high-frequency operation due to their low drive power. Although MOSFETs are not suitable for large currents, they have become a mainstay device in recent years due to their ease of integration and handling.

Types of MOSFET

MOSFET come in p-types and n-type types and are further classified into “enhancement type” and “depletion type” based on differences in operating characteristics.

1. Enhancement Type

Normal-off type, i.e., no current flows between source and drain when no voltage is applied to the gate.

2. Depletion Type

Normal-on type, i.e., current flows between source and drain even when no voltage is applied to the gate.

There are two types of MOSFET, but the enhancement type is the most commonly used for switching applications. The first MOSFET developed was the depletion type, but today it is used in very limited applications.

For example, assume a case where a negative power supply must be present in a circuit. When -5V is generated, the gate of the depletion type is connected here with a resistor of about 10kΩ.

Normally, if the negative voltage of -5V is output correctly, no current flows between the source and drain of the depletion type. However, if the negative power supply is not output correctly due to some abnormality, current flows between the source and drain, allowing an alert to be output.

How to Select MOSFET

The most important factor in selecting MOSFET is the absolute maximum rating of the source-to-drain withstand voltage VDSS. This is because the larger the withstand voltage of MOSFET, the higher its ON-resistance tends to be. If the optimum withstand voltage is not selected with a margin in consideration of the system application, ON-resistance will be unnecessarily high, leading to an increase in system power consumption.

If the voltage applied between source and drain is almost constant, the selection can be done without any problem, but the problem is how to take into account the case of a surge. If surge voltage is included, a margin of several times the steady-state rating must be considered.

Even MOSFETs with the same withstand voltage may have different withstand capacities for avalanche currents and avalanche energies. If you consider including surge energy, choose a MOSFET with high avalanche energy to obtain a MOSFET with lower breakdown voltage and lower ON-resistance.

Other Information on MOSFET

1. How Si-MOSFETs Are Different From IGBTs

Si-MOSFETs are not suitable for high-current applications. For power device applications such as high bias operation above 2V or inverter circuits for high current, IGBTs, which integrate MOSFET on the gate and a bipolar transistor on the output, are more suitable.

IGBTs are complex devices that generally require a gate driver circuit for operation, and are more difficult to handle than MOSFET because of their SOA (Safety Operation Area) and their tendency to break down when their absolute maximum ratings are exceeded, which requires a protection circuit.

Recently, SiC-MOSFETs, which use SiC, a compound semiconductor, instead of Si as the MOSFET substrate and have a larger band gap, have become popular because of their higher breakdown voltage characteristics. Since these devices have advantages and disadvantages, including cost, for the time being, they will be separated according to their applications in the market.

2. Information on SOI-CMOS

MOSFET has been improved in terms of ON-resistance and other characteristics through process miniaturization to support higher frequencies. In the past, CMOS structures with well layers were generally formed on p-type (or n-type) Si substrates called bulk substrates.

However, due to the need for high-frequency devices, especially for RF mobile applications, CMOS devices with improved high-frequency characteristics have emerged, in which the leakage path unique to MOSFET are suppressed by introducing an insulating BOX layer called SOI (Silicon On Insulator) instead of a bulk Si substrate to increase the substrate’s insulating property. CMOS devices with improved high-frequency characteristics are now available.

These devices are called SOI-CMOS and are attracting attention as devices with high-speed operation and low loss.

3. Process Miniaturization of MOSFET

The most important feature of MOSFETs are that they are semiconductor devices with low power consumption and suitable for large-scale integration. However, by making the process dimensions finer, it is possible to operate transistors at higher speeds and lower voltages and to dramatically increase the level of circuit integration.

In the case of the aforementioned CMOS-based large-scale digital processors, where integration is extremely important, the process size is said to be 3 nm as of 2022, compared to 100 nm in the early 2000s. The structure of the FinFET is based on a cutting-edge process that incorporates an ingenious transistor cross-section structure.

Although it is difficult to predict further miniaturization in the future, one technological trend that is being actively considered is the introduction of a three-dimensional chip mounting technology called a chiplet with a multi-chip structure, mainly by research and development organizations around the world.