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.
Monday, 13 October 2008
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.
Subscribe to:
Posts (Atom)
