Maintaining your fax machine is easier than you think. Keeping your office equipment maintained will help your organization keep costs down by extending the time between repairs and eventual replacement.
Fax machines use a scanner assembly to create an image of the document you want to send. Over time the scanner glass component will accumulate ink from the documents that are being scanned and this will cause the facsimile on the receiving end to have spots and other marks that were not a part of the original document. When printing a document your fax machine utilizes a print head, which through general use, will gain spots that will affect the quality of the prints of the documents you receive. Cleaning the scanner glass and print head is an easy process that will both save your organization money and improve the quality of the documents you send and receive.
Cleaning your fax machine really is an easy process. First, unplug the telephone line, then the power cord. Then wipe any dirt off of the exterior of the unit using a slightly damp cloth. Next, to clean the scanner, moisten a piece of lint-free cloth with Isopropyl alcohol and use it to remove any dirt from the glass cover of the scanner. Next, to clean the print head, moisten another lint-free cloth with Windex then wipe the edge of the print head until the dirt is removed. Finally, reconnect the power cord, then the telephone line cord. The simple maintenance of your fax machine is now complete.
At some point in your fax machine’s life the quality of the documents that are transmitted will begin to degrade. Unless there has been physical damage to the scanner glass or print head a simple cleaning will restore much of the quality that has been lost.
Friday, October 14, 2011
Perpendicular Hard Disk Drives
What is a Hard Disk Drive?
A Hard Disk Drive (HDD) is a device used by modern computers to permanently store information. The Hard Disk Drive is arguable the most essential part of a computer system in that all the information that is permanently stored is contained within its enclosure, including your computer’s Operating System (OS). Thanks to Hard Disk Drives, long gone are the days when you would have had to keep all your programs and documents stored on removable media such as Floppy Disks or CD-ROMs.
Originally invented in the mid 1950’s and made commercially available in 1956 by International Business Machines (IBM). Called RAMAC (Random Access Method of Accounting and Control), the first Hard Disk Drives contained as much as 50 platters which were 24 inches in diameter and were computers in their own right albeit with a single purpose – to store data. The entire unit which housed the hard drive was the approximate size of two large refrigerators placed side by side. In the 50 or so years since their invention, Hard Disk Drives have steadily and aggressively far out paced Moore’s law. Which stipulates that memory in computers will increase by 100% approximately every 18 months. Hard Disk Drives on the other hand have increased capacity in the same period by approximately 130%, an increase of 100% every nine months in many cases. Such capacity increases are being threatened, however.
In the years since the first Hard Disk Drive very little has changed apart from logical steps in technology such as the increased speed or improved interfaces, the basic technology has changed very little. There have been no technological leaps, as it were, for Hard Disk Drives beyond their increased miniaturisation. Apart from miniaturisation and recording media improvements the Hard Disk Drive as a device is almost identical technologically speaking, to the very first, the RAMAC.Hard Disk Drives use a similar technology as is employed in audio and video cassettes. Such audio and video cassettes use a magnetic ribbon wound around a two wheels to store data. To access a particular portion of the data contained on the magnetic ribbon, the device must wind the tape such that the beginning of the section containing the data is underneath the device that reads the data (the magnetic read/write head). This process is called sequential data retrieval because in the process of accessing the particular data, the device must sequentially read each piece of data until the data it’s looking for is found. This process is very time consuming and contributes to wear.
Hard Disks on the other hand use a circular disk-shaped platter upon which the magnetically sensitive compound is laid. Such platters are similar in concept to a Compact Disk (CD) in that the data they hold can be accessed randomly, that the recordable media is in a circular (disk) shape, and that the data is sectioned off into tracks and sectors. Data on a Hard Disk Drive can be accessed randomly because the recordable medium of Hard Disk Drives uses these separated tracks and sectors. By separating the data in such a way, it can be positioned at random intervals of the disk, depending upon the space requirements.
Anywhere from one to seven recordable platters are contained within a modern Hard Disk Drive’s metallic enclosure. Hard Disk Drive platters are perfectly circular disks made from either an aluminium alloy or a more recently a glass ceramic substrate which is a ceramic disk suspended in a glass outer shell. Onto the surfaces of a disk’s platter is laid a thin layer of a magnetically sensitive coating called the recording medium, in modern drives the mixture is a complex amalgam of different materials such as cobalt chromium platinum boron (CoCrPtB) and other such rare metals.
How does a Hard Disk Drive store data?
All information located on a computer is expressed as a series of ones and zeros (1/0), as binary digits (bits). Taking advantage of the nature of magnetic particles, that they can be polarised to magnetic north or south and that their magnetic poles can be alternated or switched when a sufficient magnetic field of the correct polarity is applied, Hard Disk Drives can store the very same sequence of bits onto a disk by polarising the required magnetic particles on the recording medium such that they represent the data being stored. Hard Disk Drives are sectioned off such that they contain both intersecting tracks and sectors. The purpose of which is to provide a logical data structure, to provide a way to distinguish between areas of data. Within each track there are a number of sectors. It is within these sectors of the Hard Disk which data is stored.
The platter of a Hard Disk Drive is coated with a magnetically sensitive coating comprised primarily of magnetically charged particles or filings which as a whole may be called the recording medium. These particulates can be magnetically aligned such that they represent binary digits, by inducing an electromagnetic field upon them via a devices read/write head. The recording media contains many billions of microscopic particles which when viewed extremely close resemble miniature metal filings. When a Hard Disk Drive records data onto the medium it takes many hundreds (usually anywhere from 500 to 100) of these magnetically sensitive particles to store a single binary digit. The increased reduction of the amount of particles required to record data is highly limited by the precision of the read/write head (the miniature device that reads and records data onto the recording medium) because the magnetic field which is used by the drive’s read/write head to read and/or record (write) data is such that it already tentatively borders nearby data.
Should it be shrunk much further in an attempt to increase precision, the likelihood of data corruption would increase vastly. Research by various parties has been on-going to find a workable solution to recording data onto much fewer or even single particles for some time now. A hard drive may record data onto the Hard Disk Drive by applying a sufficient magnetic field to the section of the recording medium (which is suspended upon the Hard Disks platter) such that the data (a series of ones and/or zeros which correspond to the information being stored) is recorded onto the medium by aligning the specified particles to the desired magnetic pole (north or south). In doing so, any previous data which was present is therefore destroyed.
Perpendicular verses Longitudinal
Ever since the late 1980’s and early 1990’s magnetic media drive manufacturers have been researching the feasibility of switching from longitudinal to perpendicular recording techniques. The advantage is clearly one of capacity: when longitudinal magnetic particles are packed together, they take up much more space than if they were to stand upright, if they stood perpendicular to the platter. More than merely a matter of initial capacity gain, perpendicular recording technology avoids a problem which has been well known in the field for many years: the super-paramagnetic effect (SPE), which affects magnetically charged particles of such small size as that used in Hard Disk Drives. “The super-paramagnetic effect is a phenomenon observed in very fine particles, where the energy required to change the direction of the magnetic moment of a particle is comparable to the ambient thermal energy” (source: Wikipedia.org).Many theories have cropped up over the years as to what density magnetic particles (described by a disks areal density) may achieve before becoming subject to SPE. At present it is suggested that anything from 100Gbit/inch2 to 150Gbit/inch2 is the physical limitation for longitudinal Hard Disk Drives, although perpendicular media solutions have been made as high as 230Gbit/inch2.
In the layering of the magnetic particulates atop a magnetic suspension layer and orienting the particles perpendicular to the platter, the recording medium can pack many more magnetically sensitive particles together in the same space than previously possible whilst keeping SPE at bay. Perpendicular recording technology does not however preclude SPE from limiting capacity in the future, more than anything perpendicular recording technology can been described as a way to give manufacturers breathing room to develop more permanent technological solutions such as holographic lithography or a multilayered recording medium. Traditional recording media manufacture consists of the spreading of recording material over a disk platter via a centrifugal force induced by spinning the platter whilst the recording material is placed atop its surface. The centrifugal force would spread the recording material across the surface, evenly spreading it in all directions. Perpendicular recording media manufacture on the other hand requires a much different technique.
The exact manufacturing process of perpendicular recording media is unsurprisingly a closely guarded secret, especially considering its recent arrival on the marketplace. From patents filed at the United States Patent and Trademark Office (USPTO), it can be taken that the predominant technique involves the laminating of magnetic and non-magnetically charged metals such as chromium, cobalt, platinum and alloys of similar; sandwiching unique layers to affect the desired result – a recording medium such that the magnetic particles are aligned perpendicular to the platter. In US patent number 6387483, filed by the NEC Corporation of Tokyo; it describes the technique as follows:The perpendicular magnetic recording medium of the embodiment is formed by laminating a Cr film, a soft magnetic under layer film, and a perpendicular magnetizing film on a substrate in this order. (Source: USPTO no. 6387483)
In longitudinal media manufacture too, laminating multiple supportive metals is achieved; in perpendicular media however, the difference is the magnetizing film as described above. Whereas traditional lamination ordinarily serves only to prevent wear and noise (both electro-mechanical and audible noise), in perpendicular media manufacture it would appear that at least some of the lamination process is used to magnetize the magnetic media particles to a perpendicular orientation. Precisely how the reorientation of magnetic media particulate is accomplished is not easy to determine, most probably because the technology is so new that such details are sketchy at best and obscure or guarded at worst. This fact is not at all surprising concerning a new technology such as perpendicular magnetic media development.
The future of storage technology
Perpendicular magnetic media technology as discussed earlier is merely a temporary solution, to find more permanent solutions we must look to much more advanced technologies. One such technology is patterned magnetic media. The process of patterned magnetic media aims to make singular magnetic particulates the object of recording bits, you will remember that current technologies requires approximately 500 to 1000 magnetic particles to store a single bit. The object of patterned media is to cut this dramatically down to a single particle per bit. Advantages of such a technology are such as reduced statistical noise associated with granular media and more increased areal density (as much as 64Gbit/inch2).
Patterned magnetic media aims to prevent the SPE barrier, or at least further decrement its effect through the use of so-called mesas and valleys. The technique uses the creation of barriers between magnetic particles, thereby avoiding the SPE complication which affects closely packed particles. Holographic Storage (a.k.a. Holographic Lithography) too is a technology that aims to increase storage capacity which is also under heavy research, and claims to be a much more permanent solution. Unlike Patterned Magnetic Media, Holographic Storage is a revolutionary step away from magnetic media and previous optoelectronic technologies.
Hard Disk Drives will always be subject to inertia and centrifugal force induced by the moving parts of the drives mechanical components (platter, read/write head), Holographic Storage has no such issues; the holographic process uses lasers in replacement of the read/write head of a Hard Disk Drive and the media itself requires no momentum (unlike the platters in Hard Disk Drives).
Such holographic storage is far from realisation, in fact it is postulated by some that it may be as much as ten years before the technology can be made into a workable solution. In direct symmetry to early memory research, research on Holographic Storage technologies seems to have banded into two camps: one of super fast data retrieval and extraordinarily high capacity storage; no doubt there will be extremely profitable markets for both.
A Hard Disk Drive (HDD) is a device used by modern computers to permanently store information. The Hard Disk Drive is arguable the most essential part of a computer system in that all the information that is permanently stored is contained within its enclosure, including your computer’s Operating System (OS). Thanks to Hard Disk Drives, long gone are the days when you would have had to keep all your programs and documents stored on removable media such as Floppy Disks or CD-ROMs.
Originally invented in the mid 1950’s and made commercially available in 1956 by International Business Machines (IBM). Called RAMAC (Random Access Method of Accounting and Control), the first Hard Disk Drives contained as much as 50 platters which were 24 inches in diameter and were computers in their own right albeit with a single purpose – to store data. The entire unit which housed the hard drive was the approximate size of two large refrigerators placed side by side. In the 50 or so years since their invention, Hard Disk Drives have steadily and aggressively far out paced Moore’s law. Which stipulates that memory in computers will increase by 100% approximately every 18 months. Hard Disk Drives on the other hand have increased capacity in the same period by approximately 130%, an increase of 100% every nine months in many cases. Such capacity increases are being threatened, however.
In the years since the first Hard Disk Drive very little has changed apart from logical steps in technology such as the increased speed or improved interfaces, the basic technology has changed very little. There have been no technological leaps, as it were, for Hard Disk Drives beyond their increased miniaturisation. Apart from miniaturisation and recording media improvements the Hard Disk Drive as a device is almost identical technologically speaking, to the very first, the RAMAC.Hard Disk Drives use a similar technology as is employed in audio and video cassettes. Such audio and video cassettes use a magnetic ribbon wound around a two wheels to store data. To access a particular portion of the data contained on the magnetic ribbon, the device must wind the tape such that the beginning of the section containing the data is underneath the device that reads the data (the magnetic read/write head). This process is called sequential data retrieval because in the process of accessing the particular data, the device must sequentially read each piece of data until the data it’s looking for is found. This process is very time consuming and contributes to wear.
Hard Disks on the other hand use a circular disk-shaped platter upon which the magnetically sensitive compound is laid. Such platters are similar in concept to a Compact Disk (CD) in that the data they hold can be accessed randomly, that the recordable media is in a circular (disk) shape, and that the data is sectioned off into tracks and sectors. Data on a Hard Disk Drive can be accessed randomly because the recordable medium of Hard Disk Drives uses these separated tracks and sectors. By separating the data in such a way, it can be positioned at random intervals of the disk, depending upon the space requirements.
Anywhere from one to seven recordable platters are contained within a modern Hard Disk Drive’s metallic enclosure. Hard Disk Drive platters are perfectly circular disks made from either an aluminium alloy or a more recently a glass ceramic substrate which is a ceramic disk suspended in a glass outer shell. Onto the surfaces of a disk’s platter is laid a thin layer of a magnetically sensitive coating called the recording medium, in modern drives the mixture is a complex amalgam of different materials such as cobalt chromium platinum boron (CoCrPtB) and other such rare metals.
How does a Hard Disk Drive store data?
All information located on a computer is expressed as a series of ones and zeros (1/0), as binary digits (bits). Taking advantage of the nature of magnetic particles, that they can be polarised to magnetic north or south and that their magnetic poles can be alternated or switched when a sufficient magnetic field of the correct polarity is applied, Hard Disk Drives can store the very same sequence of bits onto a disk by polarising the required magnetic particles on the recording medium such that they represent the data being stored. Hard Disk Drives are sectioned off such that they contain both intersecting tracks and sectors. The purpose of which is to provide a logical data structure, to provide a way to distinguish between areas of data. Within each track there are a number of sectors. It is within these sectors of the Hard Disk which data is stored.
The platter of a Hard Disk Drive is coated with a magnetically sensitive coating comprised primarily of magnetically charged particles or filings which as a whole may be called the recording medium. These particulates can be magnetically aligned such that they represent binary digits, by inducing an electromagnetic field upon them via a devices read/write head. The recording media contains many billions of microscopic particles which when viewed extremely close resemble miniature metal filings. When a Hard Disk Drive records data onto the medium it takes many hundreds (usually anywhere from 500 to 100) of these magnetically sensitive particles to store a single binary digit. The increased reduction of the amount of particles required to record data is highly limited by the precision of the read/write head (the miniature device that reads and records data onto the recording medium) because the magnetic field which is used by the drive’s read/write head to read and/or record (write) data is such that it already tentatively borders nearby data.
Should it be shrunk much further in an attempt to increase precision, the likelihood of data corruption would increase vastly. Research by various parties has been on-going to find a workable solution to recording data onto much fewer or even single particles for some time now. A hard drive may record data onto the Hard Disk Drive by applying a sufficient magnetic field to the section of the recording medium (which is suspended upon the Hard Disks platter) such that the data (a series of ones and/or zeros which correspond to the information being stored) is recorded onto the medium by aligning the specified particles to the desired magnetic pole (north or south). In doing so, any previous data which was present is therefore destroyed.
Perpendicular verses Longitudinal
Ever since the late 1980’s and early 1990’s magnetic media drive manufacturers have been researching the feasibility of switching from longitudinal to perpendicular recording techniques. The advantage is clearly one of capacity: when longitudinal magnetic particles are packed together, they take up much more space than if they were to stand upright, if they stood perpendicular to the platter. More than merely a matter of initial capacity gain, perpendicular recording technology avoids a problem which has been well known in the field for many years: the super-paramagnetic effect (SPE), which affects magnetically charged particles of such small size as that used in Hard Disk Drives. “The super-paramagnetic effect is a phenomenon observed in very fine particles, where the energy required to change the direction of the magnetic moment of a particle is comparable to the ambient thermal energy” (source: Wikipedia.org).Many theories have cropped up over the years as to what density magnetic particles (described by a disks areal density) may achieve before becoming subject to SPE. At present it is suggested that anything from 100Gbit/inch2 to 150Gbit/inch2 is the physical limitation for longitudinal Hard Disk Drives, although perpendicular media solutions have been made as high as 230Gbit/inch2.
In the layering of the magnetic particulates atop a magnetic suspension layer and orienting the particles perpendicular to the platter, the recording medium can pack many more magnetically sensitive particles together in the same space than previously possible whilst keeping SPE at bay. Perpendicular recording technology does not however preclude SPE from limiting capacity in the future, more than anything perpendicular recording technology can been described as a way to give manufacturers breathing room to develop more permanent technological solutions such as holographic lithography or a multilayered recording medium. Traditional recording media manufacture consists of the spreading of recording material over a disk platter via a centrifugal force induced by spinning the platter whilst the recording material is placed atop its surface. The centrifugal force would spread the recording material across the surface, evenly spreading it in all directions. Perpendicular recording media manufacture on the other hand requires a much different technique.
The exact manufacturing process of perpendicular recording media is unsurprisingly a closely guarded secret, especially considering its recent arrival on the marketplace. From patents filed at the United States Patent and Trademark Office (USPTO), it can be taken that the predominant technique involves the laminating of magnetic and non-magnetically charged metals such as chromium, cobalt, platinum and alloys of similar; sandwiching unique layers to affect the desired result – a recording medium such that the magnetic particles are aligned perpendicular to the platter. In US patent number 6387483, filed by the NEC Corporation of Tokyo; it describes the technique as follows:The perpendicular magnetic recording medium of the embodiment is formed by laminating a Cr film, a soft magnetic under layer film, and a perpendicular magnetizing film on a substrate in this order. (Source: USPTO no. 6387483)
In longitudinal media manufacture too, laminating multiple supportive metals is achieved; in perpendicular media however, the difference is the magnetizing film as described above. Whereas traditional lamination ordinarily serves only to prevent wear and noise (both electro-mechanical and audible noise), in perpendicular media manufacture it would appear that at least some of the lamination process is used to magnetize the magnetic media particles to a perpendicular orientation. Precisely how the reorientation of magnetic media particulate is accomplished is not easy to determine, most probably because the technology is so new that such details are sketchy at best and obscure or guarded at worst. This fact is not at all surprising concerning a new technology such as perpendicular magnetic media development.
The future of storage technology
Perpendicular magnetic media technology as discussed earlier is merely a temporary solution, to find more permanent solutions we must look to much more advanced technologies. One such technology is patterned magnetic media. The process of patterned magnetic media aims to make singular magnetic particulates the object of recording bits, you will remember that current technologies requires approximately 500 to 1000 magnetic particles to store a single bit. The object of patterned media is to cut this dramatically down to a single particle per bit. Advantages of such a technology are such as reduced statistical noise associated with granular media and more increased areal density (as much as 64Gbit/inch2).
Patterned magnetic media aims to prevent the SPE barrier, or at least further decrement its effect through the use of so-called mesas and valleys. The technique uses the creation of barriers between magnetic particles, thereby avoiding the SPE complication which affects closely packed particles. Holographic Storage (a.k.a. Holographic Lithography) too is a technology that aims to increase storage capacity which is also under heavy research, and claims to be a much more permanent solution. Unlike Patterned Magnetic Media, Holographic Storage is a revolutionary step away from magnetic media and previous optoelectronic technologies.
Hard Disk Drives will always be subject to inertia and centrifugal force induced by the moving parts of the drives mechanical components (platter, read/write head), Holographic Storage has no such issues; the holographic process uses lasers in replacement of the read/write head of a Hard Disk Drive and the media itself requires no momentum (unlike the platters in Hard Disk Drives).
Such holographic storage is far from realisation, in fact it is postulated by some that it may be as much as ten years before the technology can be made into a workable solution. In direct symmetry to early memory research, research on Holographic Storage technologies seems to have banded into two camps: one of super fast data retrieval and extraordinarily high capacity storage; no doubt there will be extremely profitable markets for both.
LED lighting modules
The appeal of using LEDs in lighting applications is growing rapidly. The numerous and significant benefits of using modules that incorporate a matrix of LEDs are being recognized by design engineers in several key industry sectors, including aerospace, architectural lighting, and the “golden egg” automotive market.
Attributes such as design flexibility, low power consumption, even and reliable light, and long lifetime distinguish LED modules from designs based on traditional filament lamps and fluorescent tubes. LEDs can also have knock-on benefits, such as greatly reducing the size and complexity of the module and simplifying the lens design.
A good example of some other benefits of LED lighting is demonstrated by an application in the cabin of a passenger aircraft. A retrofit LED unit that replaced a fluorescent-tube lighting module enabled finely controlled dimming and also provided mood lighting through the use of differently coloured LEDs.
Thermal management
Perhaps the most challenging issue when realizing a module design that uses LEDs is to manage the temperature of individual device junctions during normal operation. If the considerable amount of heat produced by all the devices in a module is not managed correctly then the junction temperatures may reach a level where the LEDs’ expected life is shortened and reliability is compromised (see Links).
LED modules typically comprise a matrix of many surface mount devices. These LEDs are soldered to an etched copper layer that provides the interconnects between the individual LEDs as well as other passive and active components that are required to complete the circuit. The small size of the LEDs and the close proximity with which they can be mounted means that designers have a huge amount of design freedom and can achieve complex lighting patterns with high levels of brightness.
The etched copper circuit is separated from a base plate – usually made of aluminum – by a thermally efficient, electrically isolating dielectric material. The characteristics and capabilities of the dielectric layer are key to the design flexibility and performance of the overall module.
Dielectric materials are made by blending thermally efficient materials such as alumina and boron nitride with other ingredients, to provide a flexible yet resilient coating on the base plate. An important characteristic of the dielectric layer is the amount of electrical isolation it provides between the copper on the topside and the metallic base plate on the underside. This is known as its dielectric strength. A typical dielectric material may possess a dielectric strength of around 800 V/mil and be coated onto the base plate to a thickness of 8–12 mils (1 mil = 1 inch–3 = 25.4 µm).
Dielectric materials used on insulated metal circuit boards usually have a thermal conductivity figure in the region of 3W/mK. This is approximately 10 times the performance achieved by FR4 (flame retardant woven glass reinforced epoxy resin) PCB material.
A further key requirement of the dielectric layer is to be able to compensate for the different coefficients of thermal expansion of the copper track on the topside of the assembly and the aluminum base plate/heat spreader on the bottom side.
Going three-dimensional
Flat sheets of insulated metal circuit board comprising copper foil, a dielectric layer and an aluminum base plate have been available for several years. In the eyes of the forward-thinking LED module designer, the main problem has been that flat sheets of insulated metal circuit board limit them to 2D shapes.
To address these limitations, new dielectric materials are becoming available that have a low modulus, meaning that they are compliant with mechanical stress and strain. These materials not only accommodate the coefficient of expansion of the metal elements of the construction, but also enable parts to be formed into right angles, and even through 360˚. This enables designers to realize complex-shaped designs and ones that form a complete circle with either internal or external copper traces.
When designing with new, formable insulated metal circuit board materials it is possible to route the tracks around corners, which alleviates the need to use connectors and hard wiring. There are several benefits to this, including enhanced reliability resulting from having fewer junctions and interconnects. Despite the slightly higher cost of the new materials, the overall cost is reduced because fewer components are needed, and assembly time is reduced.
Strength and durability
LEDs themselves are inherently durable. Mounting them on metal based circuit boards only serves to enhance their robustness and that of the finished module, providing excellent resistance to vibration and mechanical shock.
Automotive lighting clusters provide a good example of how LED modules can provide superior performance compared with traditional filament lamps. On-vehicle applications experience high levels of vibration and wide operating temperature ranges that can cause premature failure of filament lamps. In some operating conditions LEDs can last up to 100,000 hours, which means that they should not require any attention for the life of the vehicle.
The long life of LEDs also simplifies the designers’ task because it is less important to make the lighting module accessible for servicing in the finished product. This can result in a neater, more integrated installation and also in potential cost savings.
Temperature modelling
Thermal analysis software packages are available to help prove LED based module designs before they are committed to manufacture.
These software packages gather data from an integrated database about LED performance and specifications along with those of other devices that are mounted on the insulated metal circuit board. This data is combined with other information about elements of the design, including the copper traces, power and ground planes, and vias. The collated information is then processed to produce an accurate representation of the thermal performance of the design.
User-friendly graphical representations of the results enable the design engineer to quickly pinpoint areas that may require attention, right down to component and track level.
Thermal analysis software can bring significant commercial and design benefits by helping speed the time to market and reducing the number of iterations needed to reach a production-ready solution.
Attributes such as design flexibility, low power consumption, even and reliable light, and long lifetime distinguish LED modules from designs based on traditional filament lamps and fluorescent tubes. LEDs can also have knock-on benefits, such as greatly reducing the size and complexity of the module and simplifying the lens design.
A good example of some other benefits of LED lighting is demonstrated by an application in the cabin of a passenger aircraft. A retrofit LED unit that replaced a fluorescent-tube lighting module enabled finely controlled dimming and also provided mood lighting through the use of differently coloured LEDs.
Thermal management
Perhaps the most challenging issue when realizing a module design that uses LEDs is to manage the temperature of individual device junctions during normal operation. If the considerable amount of heat produced by all the devices in a module is not managed correctly then the junction temperatures may reach a level where the LEDs’ expected life is shortened and reliability is compromised (see Links).
LED modules typically comprise a matrix of many surface mount devices. These LEDs are soldered to an etched copper layer that provides the interconnects between the individual LEDs as well as other passive and active components that are required to complete the circuit. The small size of the LEDs and the close proximity with which they can be mounted means that designers have a huge amount of design freedom and can achieve complex lighting patterns with high levels of brightness.
The etched copper circuit is separated from a base plate – usually made of aluminum – by a thermally efficient, electrically isolating dielectric material. The characteristics and capabilities of the dielectric layer are key to the design flexibility and performance of the overall module.
Dielectric materials are made by blending thermally efficient materials such as alumina and boron nitride with other ingredients, to provide a flexible yet resilient coating on the base plate. An important characteristic of the dielectric layer is the amount of electrical isolation it provides between the copper on the topside and the metallic base plate on the underside. This is known as its dielectric strength. A typical dielectric material may possess a dielectric strength of around 800 V/mil and be coated onto the base plate to a thickness of 8–12 mils (1 mil = 1 inch–3 = 25.4 µm).
Dielectric materials used on insulated metal circuit boards usually have a thermal conductivity figure in the region of 3W/mK. This is approximately 10 times the performance achieved by FR4 (flame retardant woven glass reinforced epoxy resin) PCB material.
A further key requirement of the dielectric layer is to be able to compensate for the different coefficients of thermal expansion of the copper track on the topside of the assembly and the aluminum base plate/heat spreader on the bottom side.
Going three-dimensional
Flat sheets of insulated metal circuit board comprising copper foil, a dielectric layer and an aluminum base plate have been available for several years. In the eyes of the forward-thinking LED module designer, the main problem has been that flat sheets of insulated metal circuit board limit them to 2D shapes.
To address these limitations, new dielectric materials are becoming available that have a low modulus, meaning that they are compliant with mechanical stress and strain. These materials not only accommodate the coefficient of expansion of the metal elements of the construction, but also enable parts to be formed into right angles, and even through 360˚. This enables designers to realize complex-shaped designs and ones that form a complete circle with either internal or external copper traces.
When designing with new, formable insulated metal circuit board materials it is possible to route the tracks around corners, which alleviates the need to use connectors and hard wiring. There are several benefits to this, including enhanced reliability resulting from having fewer junctions and interconnects. Despite the slightly higher cost of the new materials, the overall cost is reduced because fewer components are needed, and assembly time is reduced.
Strength and durability
LEDs themselves are inherently durable. Mounting them on metal based circuit boards only serves to enhance their robustness and that of the finished module, providing excellent resistance to vibration and mechanical shock.
Automotive lighting clusters provide a good example of how LED modules can provide superior performance compared with traditional filament lamps. On-vehicle applications experience high levels of vibration and wide operating temperature ranges that can cause premature failure of filament lamps. In some operating conditions LEDs can last up to 100,000 hours, which means that they should not require any attention for the life of the vehicle.
The long life of LEDs also simplifies the designers’ task because it is less important to make the lighting module accessible for servicing in the finished product. This can result in a neater, more integrated installation and also in potential cost savings.
Temperature modelling
Thermal analysis software packages are available to help prove LED based module designs before they are committed to manufacture.
These software packages gather data from an integrated database about LED performance and specifications along with those of other devices that are mounted on the insulated metal circuit board. This data is combined with other information about elements of the design, including the copper traces, power and ground planes, and vias. The collated information is then processed to produce an accurate representation of the thermal performance of the design.
User-friendly graphical representations of the results enable the design engineer to quickly pinpoint areas that may require attention, right down to component and track level.
Thermal analysis software can bring significant commercial and design benefits by helping speed the time to market and reducing the number of iterations needed to reach a production-ready solution.
Routers - How They Work
If you've been brought up in the 21st century then you probably take a lot of things for granted that 30 years ago people just didn't have. One of those things is the Internet and its ability to be able to connect people from all over the world and allow them to interact with each other in a variety of ways including sending email, visiting web sites, joining forums, attending online chats and countless other things. But none of this would be possible if it weren't for a device that most people have never seen and probably don't even know exist, called a router.
Routers are pieces of equipment that send messages from everyone connected to the network along thousands of different pathways. We're going to take a behind the scenes look at exactly how these routers work.
Let's say you're sending an email to a friend of yours who is living across country or even in another part of the world. How does the email know to end up on your friend's computer instead of all the other millions of computers all over the world? A good part of the work to get these messages from one computer to another is handled by routers. Rather than pass messages within networks, routers pass messages from one network to another.
To get an idea of how this works, let's take a very simple example.
Let's say you have two departments. Department A with 5 employees and Department B with 5 employees. Let's say that Employee 1 from Department A wants to send an email to Employee 3 at Department B. Each department is part of its own network of computers. A router links the two networks together so that they can communicate with each other. It is the only piece of equipment that sees both networks. Many people ask, why not just make one network? The simple answer is that if the two departments do two completely different jobs for the company and send massive amounts of info within the department, you don't want to slow down the other department with the one department's info. To ease what they call the "traffic burden" the two departments are separated into two networks with a router put between them to connect them just in case they do want to communicate for some reason.
The way the router knows what to send where is with what is called a configuration table. These configuration table consists of info on which connections lead to which addresses, priorities for each connection, and rules for how to handle the passing of info between networks. The router then has two basic jobs. The main task is to make sure that information doesn't go where it's not needed so that the volume of data doesn't clog up the network and the next task is to make sure the information goes to where it's supposed to go.
To simplify how this happens, the router looks at the destination address of each packet sent from the source location. It checks its table to see where this address is and sends each packet to that address, bypassing all the other addresses in the network so as not to slow the network down.
In future articles we'll take a more in depth and technical look at how packets are actually routed. Get on your thinking gear for this one.
Routers are pieces of equipment that send messages from everyone connected to the network along thousands of different pathways. We're going to take a behind the scenes look at exactly how these routers work.
Let's say you're sending an email to a friend of yours who is living across country or even in another part of the world. How does the email know to end up on your friend's computer instead of all the other millions of computers all over the world? A good part of the work to get these messages from one computer to another is handled by routers. Rather than pass messages within networks, routers pass messages from one network to another.
To get an idea of how this works, let's take a very simple example.
Let's say you have two departments. Department A with 5 employees and Department B with 5 employees. Let's say that Employee 1 from Department A wants to send an email to Employee 3 at Department B. Each department is part of its own network of computers. A router links the two networks together so that they can communicate with each other. It is the only piece of equipment that sees both networks. Many people ask, why not just make one network? The simple answer is that if the two departments do two completely different jobs for the company and send massive amounts of info within the department, you don't want to slow down the other department with the one department's info. To ease what they call the "traffic burden" the two departments are separated into two networks with a router put between them to connect them just in case they do want to communicate for some reason.
The way the router knows what to send where is with what is called a configuration table. These configuration table consists of info on which connections lead to which addresses, priorities for each connection, and rules for how to handle the passing of info between networks. The router then has two basic jobs. The main task is to make sure that information doesn't go where it's not needed so that the volume of data doesn't clog up the network and the next task is to make sure the information goes to where it's supposed to go.
To simplify how this happens, the router looks at the destination address of each packet sent from the source location. It checks its table to see where this address is and sends each packet to that address, bypassing all the other addresses in the network so as not to slow the network down.
In future articles we'll take a more in depth and technical look at how packets are actually routed. Get on your thinking gear for this one.
How to Convert VHS to DVD with a DVD Recorder
When preserving your favorite movies or memories, the standard used to be VHS video tapes. But with the advancement of DVD technology, the advantages of DVDs proved to outweigh those of VCR tapes. Video tapes can wear out over time, becoming bent, damaged or dirty. The cassette casings are vulnerable to damage as well, rendering the tape inside useless. Storage is easier with DVDs since they take up less space than videos. Not to mention the quality of picture and sound is higher on DVDs.
So the question becomes, how do I convert my video tapes to DVDs in order to preserve them for my future enjoyment? There are several options. First, you could use a VHS to DVD conversion service that will do the transfer for you. However, if you have a great deal of videos to convert, over time you'll save money by doing the conversions yourself in the convenience of your home.
The computer savvy among us will use their computer to transfer their videos to DVD. It requires copying the video to a digital file on the computer using an analog converter. The file gets compressed into MPEG-2 format before being burned onto a DVD. This method takes some time, but it does allow you to make changes to the video, like special effects or music, before you burn it to the DVD. Depending on the burning software that you use, you might be able to add a menu or other special features. However, the process can be quite slow because you have to transfer the file twice: first from the video to the computer and then again from the computer to the DVD.
So in order to save time and effort, you can copy the tapes to a DVD without the use of a computer. There are two ways to do this:
If you do the conversion yourself, always follow the manufacturer's instructions to ensure you capture the video appropriately. Make sure that you have cleaned the heads of the VCR between copying videos. Old tapes carry a lot of dust or other particles that can clog up your VCR. And since you are copying directly from the video to the DVD, whatever picture quality issues you have with the video will appear on the DVD. Understand that if you have videos which are recorded at SLP (6 hours of video on a tape) you will not get the same quality of recording onto a DVD as if the video was recorded at SP (2 hours of video on a tape). If you find the quality is not acceptable for you, consider changing your method of converting videos to DVD. However, for many people, the time and energy saved in converting the videos on their own will outweigh any concerns over video quality.
So the question becomes, how do I convert my video tapes to DVDs in order to preserve them for my future enjoyment? There are several options. First, you could use a VHS to DVD conversion service that will do the transfer for you. However, if you have a great deal of videos to convert, over time you'll save money by doing the conversions yourself in the convenience of your home.
The computer savvy among us will use their computer to transfer their videos to DVD. It requires copying the video to a digital file on the computer using an analog converter. The file gets compressed into MPEG-2 format before being burned onto a DVD. This method takes some time, but it does allow you to make changes to the video, like special effects or music, before you burn it to the DVD. Depending on the burning software that you use, you might be able to add a menu or other special features. However, the process can be quite slow because you have to transfer the file twice: first from the video to the computer and then again from the computer to the DVD.
So in order to save time and effort, you can copy the tapes to a DVD without the use of a computer. There are two ways to do this:
- The first involves buying a DVD recorder that allows input from another source. You simply connect your VCR by cable to the DVD recorder. Then while the video plays, it is also recording. If you choose this option, consider purchasing a video processor called a proc amp or a time base corrector. These devices stabilize and improve the quality of the analog video as it is fed to the DVD recorder and can greatly improve the resulting images that you get on the DVD.
- The second option is to purchase a combination DVD/VCR recorder. It does the same thing as the previous option without needing to connect any cables. If you are planning to copy a lot of videos, it is worth your time and effort to find out what kind of processing the machine does to the analog signal from the video tape before it converts it to the digital signal that gets recorded in DVD format. You want the best possible result that you can get.
If you do the conversion yourself, always follow the manufacturer's instructions to ensure you capture the video appropriately. Make sure that you have cleaned the heads of the VCR between copying videos. Old tapes carry a lot of dust or other particles that can clog up your VCR. And since you are copying directly from the video to the DVD, whatever picture quality issues you have with the video will appear on the DVD. Understand that if you have videos which are recorded at SLP (6 hours of video on a tape) you will not get the same quality of recording onto a DVD as if the video was recorded at SP (2 hours of video on a tape). If you find the quality is not acceptable for you, consider changing your method of converting videos to DVD. However, for many people, the time and energy saved in converting the videos on their own will outweigh any concerns over video quality.
Cheap Laptops: How to Buy the Right One
Cheap and inexpensive laptops are available plenty in number in the market. While buying laptops, price factor alone should not limit the purchase. Cheap laptops are made available to the consumer to suit the budget as well as specific requirements. The person buying a laptop should be very clear regarding the required features, options and then conduct a search to match his needs. The place of purchasing cheap laptops is also important. There are various sources from which a person can buy cheap laptops. Out of all the sources, Internet is considered to be the best place to purchase laptops. A same laptop model can be sold at different prices in different websites. The purchaser can easily select the one with a lesser price easily. Also it is better to avoid impulse purchase as far as laptops are concerned, since it is impossible for a lay man to comprehend the hi-tech lingo associated with laptop computers like the flat panel TFT, WiFi connectivity, wireless and many more features.
Features to be considered before buying cheap laptops:
Processor of the laptop: A processor is very important to run applications and to perform on-screen tasks. The processor should not be less than 1.4 GHz as it may affect the quick performance of the laptop. For day today operation using word processing, e-mail, spread sheets etc the above processor speed is enough. When Pentium processors are bought they assure a longer battery life and at the same time they are quick.
Screen size of the cheap laptops should not be less than 12.1 inches. The screen size of laptops is measured diagonally. The larger the screen size, the higher the resolution, making it easy for viewing more information all at once.
Laptops should have a good battery life as they are carried with the operator for presentations, or for calculations whenever and wherever they are required. A laptop with a good battery life should be able to perform jobs ranging from 3 to 7 hours of non stop work without any electrical charge required in between. Lithium ion rechargeable batteries are an ideal choice.
The hard drive capacity is very important to store large amount of data on to the laptops. A cheap laptop can be chosen with a hard drive capacity ranging from 20 GB to 40 GB depending on the person’s usage.
The keyboards of laptops are different from those of the desktop computers. The keys on the keypad are relatively smaller and are packed closely with each other. Hence, it is very important to see if it can be handled comfortably before purchasing a cheap laptop.
Touchpad or pointing stick inbuilt with a laptop can be more very useful than a mouse connected via USB port. Two USB ports are more than enough for a cheap laptop; in case more ports are required the user can use an external USB hub.
The ideal weight of the laptops should be between 4 – 10 pounds, never go for a more weighing laptop even if it comes for a very cheap amount. In order to reduce the weight of the laptops, external CD drives can be used. For communications a built in Ethernet port is more ideal than the serial ports or infrared ports.
Features to be considered before buying cheap laptops:
Processor of the laptop: A processor is very important to run applications and to perform on-screen tasks. The processor should not be less than 1.4 GHz as it may affect the quick performance of the laptop. For day today operation using word processing, e-mail, spread sheets etc the above processor speed is enough. When Pentium processors are bought they assure a longer battery life and at the same time they are quick.
Screen size of the cheap laptops should not be less than 12.1 inches. The screen size of laptops is measured diagonally. The larger the screen size, the higher the resolution, making it easy for viewing more information all at once.
Laptops should have a good battery life as they are carried with the operator for presentations, or for calculations whenever and wherever they are required. A laptop with a good battery life should be able to perform jobs ranging from 3 to 7 hours of non stop work without any electrical charge required in between. Lithium ion rechargeable batteries are an ideal choice.
The hard drive capacity is very important to store large amount of data on to the laptops. A cheap laptop can be chosen with a hard drive capacity ranging from 20 GB to 40 GB depending on the person’s usage.
The keyboards of laptops are different from those of the desktop computers. The keys on the keypad are relatively smaller and are packed closely with each other. Hence, it is very important to see if it can be handled comfortably before purchasing a cheap laptop.
Touchpad or pointing stick inbuilt with a laptop can be more very useful than a mouse connected via USB port. Two USB ports are more than enough for a cheap laptop; in case more ports are required the user can use an external USB hub.
The ideal weight of the laptops should be between 4 – 10 pounds, never go for a more weighing laptop even if it comes for a very cheap amount. In order to reduce the weight of the laptops, external CD drives can be used. For communications a built in Ethernet port is more ideal than the serial ports or infrared ports.
Laser Printers
Like with many other things in the world of printing, laser printers have come a long way in the past few years. They have gone from being found almost exclusively in offices to being offered at $100 for a home user. Although they are better for a lot of people, some have a hard time imagining themselves buying a laser printer for their home. A lot of people have the idea that laser printers are just the big clunky machines in their offices where the toner cartridges cost a fortune. However, if you are someone who prints out a large amount of documents and is tired of always having to buy new black inkjet cartridges, laser printers can be the solution. Once you get past the initial sticker shock of buying laser toner cartridges, you will realize the numbers for an entry level laser printer versus an inkjet printer look something like this:
Typical toner cartridge - $50-$60
Page yield - 2,000-3,000 pages
Average cost per page - 2-2.5 cents per page
Typical inkjet cartridge - $20-$30
Page yield - 400-500 pages
Average cost per page - 4-6 cents per page
Although these are just averages and may not seem all that different, in general if you are printing documents, it will probably cost you twice as much to run an inkjet printer than a laser printer. It is better to think of things in the long term when it comes to laser printers, because only then will you truly appreciate their value. If you buy a laser printer and then a backup toner cartridge at the same time, by the time you will have finished that second cartridge, you would have gone through roughly 10 inkjet cartridges.
So if you aren't into printing color, then you are probably better off going with a laser printer over a standard inkjet printer. You will appreciate the speed and low maintenance of a laser printer, while also saving money on printer ink in the long run.
Typical toner cartridge - $50-$60
Page yield - 2,000-3,000 pages
Average cost per page - 2-2.5 cents per page
Typical inkjet cartridge - $20-$30
Page yield - 400-500 pages
Average cost per page - 4-6 cents per page
Although these are just averages and may not seem all that different, in general if you are printing documents, it will probably cost you twice as much to run an inkjet printer than a laser printer. It is better to think of things in the long term when it comes to laser printers, because only then will you truly appreciate their value. If you buy a laser printer and then a backup toner cartridge at the same time, by the time you will have finished that second cartridge, you would have gone through roughly 10 inkjet cartridges.
So if you aren't into printing color, then you are probably better off going with a laser printer over a standard inkjet printer. You will appreciate the speed and low maintenance of a laser printer, while also saving money on printer ink in the long run.
Subscribe to:
Posts (Atom)