There is a reason why most offices use laser printers for printing long text documents. Even though the price of a laser printer is higher than the price of an inkjet printer, the consumables for laser printers (toner) are on average cheaper than those for inkjet printers (inks).
Besides the low cost of consumables, the laser printers are also preferred because of their good ability to handle printing tasks coming from different computers on the network. Thus a small office can use a single printer for all printing needs.
As personal printers, laser printers are becoming more and more affordable. With further advance in technology their price is predicted to continue to drop.
Showing posts with label Articles about Printing. Show all posts
Showing posts with label Articles about Printing. Show all posts
Monday, 13 October 2008
Why is printout by laser printers so durable?
Besides the high speed, the other main advantage of laser printers is the durability of printout. This is a consequence of the way the toner is attached to the paper. Instead of just being absorbed in the paper as in inkjet printers, the toner is actually fusing with the surface of the paper. This makes it possible for the toner to be printed not only on paper but also on other printing media. The fusion rolls will always make sure that the toner will not be smudged or harmed in any way once the paper has come out of the printer. In addition, the fusion rolls give even more flexibility for the output by allowing the heat and pressure applied by them to be controlled. Thus the user can decide how his final output will look like, which can include matte and gloss.
... what about color laser printing?
How do they manage to produce a quality printout so fast?
Many of you probably know that in the beginning of laser printing technology there were only black printouts. This is known as monochrome printing. But why not have color as well since a successful technology already exists? The color printout is produced the same way as the black one (refer to: What does laser have to do with printing?), however the whole process repeats for every color – cyan, yellow, magenta and black. Different combinations of these 4 basic colors can generate the full color spectrum.
The color laser printer works in either of two ways. Each color can be applied on the drum and consequently on the paper one at a time OR all colors are first applied on a plate and then pasted on the paper at the same time. There are also more advanced and thus more expensive printers, which have a full printer unit (including laser, drum and toner system), for each color. The paper goes through a small journey inside the printer and collects all the exact proportion of each color on the way.
Usually the resolution of color laser printers is 600 or 1200 dpi. Printers with lower resolution generally do not give a nice continuous color tone on the printout.
Many of you probably know that in the beginning of laser printing technology there were only black printouts. This is known as monochrome printing. But why not have color as well since a successful technology already exists? The color printout is produced the same way as the black one (refer to: What does laser have to do with printing?), however the whole process repeats for every color – cyan, yellow, magenta and black. Different combinations of these 4 basic colors can generate the full color spectrum.
The color laser printer works in either of two ways. Each color can be applied on the drum and consequently on the paper one at a time OR all colors are first applied on a plate and then pasted on the paper at the same time. There are also more advanced and thus more expensive printers, which have a full printer unit (including laser, drum and toner system), for each color. The paper goes through a small journey inside the printer and collects all the exact proportion of each color on the way.
Usually the resolution of color laser printers is 600 or 1200 dpi. Printers with lower resolution generally do not give a nice continuous color tone on the printout.
What does laser have to do with printing?
The arrival of the laser printers made many people wonder how exactly laser can be used inside a printer. Here you will get to know briefly this fairly recent printing method.
How is it possible for a laser to produce character or graphics on paper? The essence of the answer is hidden within one basic scientific principle: static electricity. We are all familiar with the situation of removing a pullover and having our hairs up in the air after that. This happens because electrical charge is built up on your hair and on the clothes you are wearing – one is positive and the other negative. This causes them to attract.
How is the principle of static electricity used inside a printer?
The drum – one of the major components in laser printers – receives a positive charge by a special wire (corona wire), which has an electrical current running through it. When the paper is fed into the printer, the drum starts rotating. Then laser plays its role – it "draws" on the drum all characters, which need to be printed. All the points at which the precise laser beam is directed become negatively charged. The rest of the drum remains positively charged.
Once the laser has done its job, the printer brings into use the positively charged toner. This is very fine black powder. The toner immediately sticks to the negatively charged areas of the drum. During this time the paper is rolling on a belt under the drum. The drum is ready to paste the fixed toner pattern on the paper, but before it does that the paper receives a negative charge by the same wire, which charged the drum positive. The negative charge of the paper is stronger than the negative charge that is holding the positively charged toner on the drum. Therefore the paper attracts the toner. Right after this the paper is discharged by another wire, called detac corona wire so that it does not get attracted to the positive drum. At the same time the drum goes through another procedure: a discharge lamp goes through its entire surface and erases the electrical image. Then the drum’s surface again receives a positive charge from the corona wire, making it ready for the next page waiting to be printed.
The drum and the paper move at the same speed so the image that was on the drum is pasted in exactly the same way on the paper. One more operation is needed before you can take your ready printout – the toner needs to become tightly fixed to the paper fibers. For this purpose the paper is rolled quickly between two heated rollers, called fusers. They melt the toner and thus it fuses with the paper. Then the paper arrives hot at the output tray, from where you can take it.
Did you like this article? Continue to the further reading:
Curious fact: The laser does not move on its own. In fact, it is always directed in the same way, but it has a moveable mirror in front, which bounces the beam. Then the beam goes through a series of lenses and gets projected on the drum’s surface.
Curious fact: The laser accounts for the high speed and the high precision of laser printers. The reason lies in the fact that a laser beam can move much faster than any inkjet cartridge. The high precision comes from the fact that the laser always has the same shape and diameter, which cannot be controlled to such a high extent in an ink droplet.
How is it possible for a laser to produce character or graphics on paper? The essence of the answer is hidden within one basic scientific principle: static electricity. We are all familiar with the situation of removing a pullover and having our hairs up in the air after that. This happens because electrical charge is built up on your hair and on the clothes you are wearing – one is positive and the other negative. This causes them to attract.
How is the principle of static electricity used inside a printer?
The drum – one of the major components in laser printers – receives a positive charge by a special wire (corona wire), which has an electrical current running through it. When the paper is fed into the printer, the drum starts rotating. Then laser plays its role – it "draws" on the drum all characters, which need to be printed. All the points at which the precise laser beam is directed become negatively charged. The rest of the drum remains positively charged.
Once the laser has done its job, the printer brings into use the positively charged toner. This is very fine black powder. The toner immediately sticks to the negatively charged areas of the drum. During this time the paper is rolling on a belt under the drum. The drum is ready to paste the fixed toner pattern on the paper, but before it does that the paper receives a negative charge by the same wire, which charged the drum positive. The negative charge of the paper is stronger than the negative charge that is holding the positively charged toner on the drum. Therefore the paper attracts the toner. Right after this the paper is discharged by another wire, called detac corona wire so that it does not get attracted to the positive drum. At the same time the drum goes through another procedure: a discharge lamp goes through its entire surface and erases the electrical image. Then the drum’s surface again receives a positive charge from the corona wire, making it ready for the next page waiting to be printed.
The drum and the paper move at the same speed so the image that was on the drum is pasted in exactly the same way on the paper. One more operation is needed before you can take your ready printout – the toner needs to become tightly fixed to the paper fibers. For this purpose the paper is rolled quickly between two heated rollers, called fusers. They melt the toner and thus it fuses with the paper. Then the paper arrives hot at the output tray, from where you can take it.
Did you like this article? Continue to the further reading:
Curious fact: The laser does not move on its own. In fact, it is always directed in the same way, but it has a moveable mirror in front, which bounces the beam. Then the beam goes through a series of lenses and gets projected on the drum’s surface.
Curious fact: The laser accounts for the high speed and the high precision of laser printers. The reason lies in the fact that a laser beam can move much faster than any inkjet cartridge. The high precision comes from the fact that the laser always has the same shape and diameter, which cannot be controlled to such a high extent in an ink droplet.
The importance of paper
This article is dedicated to one of the most needed commodities in everyday life – paper. Understanding how it is made and its characteristics is an important step to more successful printing.
Some history: The term paper comes from papyrus. This is the Greek name for the ancient material on which the Egyptian used to write as early as 3000 BC. Back then it was made from papyrus plants.
Today paper is mostly made by combining natural vegetable fibers. These fibers are composed of cellulose and are further held together by hydrogen bonding. In order to achieve certain physical properties, paper manufacturers incorporate synthetic fibers as well. These fibers are contained in different kinds of trees.
When you want to print a good image on your inkjet printer, the paper needs to have certain characteristics. You may have noticed that standard copier paper gives you an image that is less bright and vivid than an image on inkjet paper. The two main factors that will have significance for your image quality are brightness and absorption.
A smooth paper will have a brighter image than a rough one, because the light is reflected back in the same direction. Most magazines use smooth paper for better quality images. Light projected on rough surface is reflected in several directions. Thus the pictures in newspapers, which are usually printed on more rough paper, look less bright and less clear.
Absorption also plays an important role in image quality. Once the ink strikes the paper, it is supposed to stay on it shaped as a nice dot. It should not be too much absorbed in the paper since this will cause the dot to spread sideways on the paper. This in turn will make the picture look blurry, especially at the edge of every object or character.
It is important whenever you print to adjust the settings in the printer to suit the paper, so that the right amount of ink is sprayed. Usually papers are characterized by their weight and resolution achieved. They can also be of two types – glossy (smooth) or matte (very rough). If you want to print only text, you can usually take a standard general purpose office paper (80 – 100 g/m?) for both inkjet and laser printer. For graphics, however, you should use other coated papers. They have a waxy film, which keeps the ink on the surface and thus allows printers to produce an image at a significantly bigger resolution. A printer that can achieve 720x720 dpi on normal paper can reach 1440x720 dpi when using coated paper.
Thanks to paper properties, inkjet papers can give you a magnificent image with vivid live colors and photographic quality.
Some history: The term paper comes from papyrus. This is the Greek name for the ancient material on which the Egyptian used to write as early as 3000 BC. Back then it was made from papyrus plants.
Today paper is mostly made by combining natural vegetable fibers. These fibers are composed of cellulose and are further held together by hydrogen bonding. In order to achieve certain physical properties, paper manufacturers incorporate synthetic fibers as well. These fibers are contained in different kinds of trees.
When you want to print a good image on your inkjet printer, the paper needs to have certain characteristics. You may have noticed that standard copier paper gives you an image that is less bright and vivid than an image on inkjet paper. The two main factors that will have significance for your image quality are brightness and absorption.
A smooth paper will have a brighter image than a rough one, because the light is reflected back in the same direction. Most magazines use smooth paper for better quality images. Light projected on rough surface is reflected in several directions. Thus the pictures in newspapers, which are usually printed on more rough paper, look less bright and less clear.
Absorption also plays an important role in image quality. Once the ink strikes the paper, it is supposed to stay on it shaped as a nice dot. It should not be too much absorbed in the paper since this will cause the dot to spread sideways on the paper. This in turn will make the picture look blurry, especially at the edge of every object or character.
It is important whenever you print to adjust the settings in the printer to suit the paper, so that the right amount of ink is sprayed. Usually papers are characterized by their weight and resolution achieved. They can also be of two types – glossy (smooth) or matte (very rough). If you want to print only text, you can usually take a standard general purpose office paper (80 – 100 g/m?) for both inkjet and laser printer. For graphics, however, you should use other coated papers. They have a waxy film, which keeps the ink on the surface and thus allows printers to produce an image at a significantly bigger resolution. A printer that can achieve 720x720 dpi on normal paper can reach 1440x720 dpi when using coated paper.
Thanks to paper properties, inkjet papers can give you a magnificent image with vivid live colors and photographic quality.
How similar is a Dot Matrix Printer to a Typewriter?
A dot matrix printer or impact matrix printer is a type of computer printer, which operates with a print head that runs back and forth on the page, striking an ink-soaked cloth ribbon against the paper. The print head has a set of tiny steel pins - usually between 9 and 24 and when it is running the printer generally prints one line of text at a time. When the pins strike on the fabric or carbon ribbon they create dots on the paper. Characters are composed of patterns of these dots by moving the print head laterally across the page and striking at a very close distance from the previous strike. The pins are activated by solenoids (small wire coils). These solenoids are energized at a particular time, depending on what character should be printed. Timing of the signals sent to the solenoids is programmed into the printer for each character. Multiple passes of the print head may be used to increase the effective number of pins and improve print quality.
The strikes on ink-soaked cloth make these machines resemble a typewriter. However, unlike a typewriter, letters are drawn out of a dot matrix, and this way, varied fonts and arbitrary graphics can be produced. Facing the ribbon and the paper is a small guide plate pierced with holes to serve as guides for the pins.
Dot matrix printers can be very durable, but several problems can make it wear out. Ink often enters the guide plate of the print head, causing grit to adhere to it. This grit slowly causes the channels in the guide plate to wear from circles into ovals or other shapeless slots, providing less and less accurate guidance to the printing wires. Eventually the printing becomes too unclear to read. Other problematic issues about these types of printers are their stepper modes of use, drivers and interconnect cables.
It is important to know that nearly all printers, including inkjet and laser printer produce dot matrices. Thus, the name dot matrix printer is not used correctly to describe only this type of printer. Still, in everyday language, other types of printers are almost never called dot matrix printer in order to avoid confusion with dot matrix impact printers.
The strikes on ink-soaked cloth make these machines resemble a typewriter. However, unlike a typewriter, letters are drawn out of a dot matrix, and this way, varied fonts and arbitrary graphics can be produced. Facing the ribbon and the paper is a small guide plate pierced with holes to serve as guides for the pins.
Dot matrix printers can be very durable, but several problems can make it wear out. Ink often enters the guide plate of the print head, causing grit to adhere to it. This grit slowly causes the channels in the guide plate to wear from circles into ovals or other shapeless slots, providing less and less accurate guidance to the printing wires. Eventually the printing becomes too unclear to read. Other problematic issues about these types of printers are their stepper modes of use, drivers and interconnect cables.
It is important to know that nearly all printers, including inkjet and laser printer produce dot matrices. Thus, the name dot matrix printer is not used correctly to describe only this type of printer. Still, in everyday language, other types of printers are almost never called dot matrix printer in order to avoid confusion with dot matrix impact printers.
What technologies are hidden behind the name "inkjet"?
Depending on the type, inkjet printers can form ink droplets in a different way. Nowadays printer manufacturers use two main technologies. One uses heat; the other – vibration. A third technology uses continuous flow of ink and will be discussed briefly.
Thermal bubble, also known as bubble jet, is a technology used in printers made by HP (Hewlett Packard), Canon and Lexmark. It was discovered in 1977 by a Canon engineer. The name bubble jet comes from the fact that in order to push ink through the nozzles, small resistors create heat, which vaporizes and creates a bubble. While the bubble is expanding, some parts of the ink are pushed by it through the nozzle on the paper. Once the bubble pops, a vacuum is created which pulls more ink from the cartridge into the print head.
The bubble jet print head usually has 64 or 128 nozzles, which can send a droplet at the same time. The inks are dye-based or water-soluble pigment. The resolution varies between 300 and 600 dpi, sometimes up to 1200. One drawback of this technology is that the ink should be heat-resistant. The next drawback follows from the same heating techniques – the ink needs to cool down, which requires additional time. Monochrome text is printed at the speed of 4-8 pages per minute. Color and graphics – 2-4ppm. Still one advantage remains, the bubble jet print head is usually produced at less cost than other inkjet technologies.
The Epson printers function thanks to a patented technology with piezo crystals. This utilizes the fact that piezo crystals change their properties if a current is applied on them. A piezo crystal is sitting behind each nozzle. The crystal vibrates every time when it receives a small electric charge. If it vibrates inwards, it send ink through the nozzle. If it vibrates outwards, more ink is pulled from the reservoir into the printhead. The good sides of this technology is that it allows for more control on the shape and size of the droplet. The number of nozzles is 128 for black and 64 for each of the three colors CMY. The basic resolution is 720 dpi, but it can be improved to 1440dpi. In addition, there is no heating and cooling of the ink, so time is saved. The inks used for this printing technology are very quick-drying. They can be of bigger variety than the ones used in thermal inkjet technology. Once they penetrate the paper, they tend to hold their shape and not spread, which creates a very good image on different coated papers.
In 1951 Siemens introduced another printing technology – continuous inkjet. It involves a continuous stream of ink droplets. This technology has the advantage that the nozzles do not clog because the jet is always in use. However the fluid handling system is usually very complicated.
Thermal bubble, also known as bubble jet, is a technology used in printers made by HP (Hewlett Packard), Canon and Lexmark. It was discovered in 1977 by a Canon engineer. The name bubble jet comes from the fact that in order to push ink through the nozzles, small resistors create heat, which vaporizes and creates a bubble. While the bubble is expanding, some parts of the ink are pushed by it through the nozzle on the paper. Once the bubble pops, a vacuum is created which pulls more ink from the cartridge into the print head.
The bubble jet print head usually has 64 or 128 nozzles, which can send a droplet at the same time. The inks are dye-based or water-soluble pigment. The resolution varies between 300 and 600 dpi, sometimes up to 1200. One drawback of this technology is that the ink should be heat-resistant. The next drawback follows from the same heating techniques – the ink needs to cool down, which requires additional time. Monochrome text is printed at the speed of 4-8 pages per minute. Color and graphics – 2-4ppm. Still one advantage remains, the bubble jet print head is usually produced at less cost than other inkjet technologies.
The Epson printers function thanks to a patented technology with piezo crystals. This utilizes the fact that piezo crystals change their properties if a current is applied on them. A piezo crystal is sitting behind each nozzle. The crystal vibrates every time when it receives a small electric charge. If it vibrates inwards, it send ink through the nozzle. If it vibrates outwards, more ink is pulled from the reservoir into the printhead. The good sides of this technology is that it allows for more control on the shape and size of the droplet. The number of nozzles is 128 for black and 64 for each of the three colors CMY. The basic resolution is 720 dpi, but it can be improved to 1440dpi. In addition, there is no heating and cooling of the ink, so time is saved. The inks used for this printing technology are very quick-drying. They can be of bigger variety than the ones used in thermal inkjet technology. Once they penetrate the paper, they tend to hold their shape and not spread, which creates a very good image on different coated papers.
In 1951 Siemens introduced another printing technology – continuous inkjet. It involves a continuous stream of ink droplets. This technology has the advantage that the nozzles do not clog because the jet is always in use. However the fluid handling system is usually very complicated.
What kind of printing technologies have been invented until today?
Many people would give the following answer to this question: dot-matrix, inkjet and laser technology. You would be right if you are listing the most common ones. However, there are more ways to print. In this article you can get to know them. For visual representation, please check the end of the article. The easiest way for you to think about printing technologies is to make a distinction between impact and non-impact technology.
Dot matrix printers – they produce printout through the help of series of small pins, which strike an inked ribbon and thus cause the ink to transfer to the paper at the point if impact.
Character printers – they are much like computerized typewriters. They have a ball or series of bars with actual letters and numbers embossed on the surface. The required character is struck against the ink ribbon, transferring the character's image to the paper.
Inkjet printers make a printout by spraying drops of ink straight on the paper with the help of nozzles.
Laser printers – they use toner, static electricity, and heat to place and attach the ink onto the paper. Solid ink printers have sticks of wax-like ink that are melted and applied to the paper. The ink then hardens and the printout is ready.
Dye-sublimation printers contain a long roll of transparent film which resembles sheets of red-, blue-, yellow- and gray-colored cellophane attached together end to end. This film has inside solid dyes of to the four basic colors used in printing: cyan, magenta, yellow and black (CMYK). The print head uses a heating element that differs in temperature, depending on the amount of a certain color that needs to be applied. The dyes vaporize and enter the glossy surface of the paper before they return to solid form. The printer runs the long roll completely over the paper for each of the basic colors. Thus step by step the image is produced. Thermal wax printers function as a hybrid of dye-sublimation and solid ink technologies. They use a ribbon with alternating CMYK color bands. The ribbon passes in front of a print head which has many tiny heated pins. The pins make the wax melt and attach to the paper, where it hardens right away.
Thermal autochrome printers are different from other printer types because they have the color in the paper instead of in the printer. Wrapped between a base material and a protective heat-resistant layer, the three layers (cyan, magenta and yellow) in the paper, are activated by the application of a specific amount of heat. The print head has a heating element that can differ in temperature. When it goes over the paper three times, it provides the required temperature for each color layer.
- Impact – these printers include all those that have a mechanism for touching the paper. They include:
Dot matrix printers – they produce printout through the help of series of small pins, which strike an inked ribbon and thus cause the ink to transfer to the paper at the point if impact.
Character printers – they are much like computerized typewriters. They have a ball or series of bars with actual letters and numbers embossed on the surface. The required character is struck against the ink ribbon, transferring the character's image to the paper.
- Non-impact – these printers do not touch the paper while producing a printout. Here they are:
Inkjet printers make a printout by spraying drops of ink straight on the paper with the help of nozzles.
Laser printers – they use toner, static electricity, and heat to place and attach the ink onto the paper. Solid ink printers have sticks of wax-like ink that are melted and applied to the paper. The ink then hardens and the printout is ready.
Dye-sublimation printers contain a long roll of transparent film which resembles sheets of red-, blue-, yellow- and gray-colored cellophane attached together end to end. This film has inside solid dyes of to the four basic colors used in printing: cyan, magenta, yellow and black (CMYK). The print head uses a heating element that differs in temperature, depending on the amount of a certain color that needs to be applied. The dyes vaporize and enter the glossy surface of the paper before they return to solid form. The printer runs the long roll completely over the paper for each of the basic colors. Thus step by step the image is produced. Thermal wax printers function as a hybrid of dye-sublimation and solid ink technologies. They use a ribbon with alternating CMYK color bands. The ribbon passes in front of a print head which has many tiny heated pins. The pins make the wax melt and attach to the paper, where it hardens right away.
Thermal autochrome printers are different from other printer types because they have the color in the paper instead of in the printer. Wrapped between a base material and a protective heat-resistant layer, the three layers (cyan, magenta and yellow) in the paper, are activated by the application of a specific amount of heat. The print head has a heating element that can differ in temperature. When it goes over the paper three times, it provides the required temperature for each color layer.
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