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What is a laser printer?
A laser printer is an electric printer that tends to emit light from a film, or photosensitive drum, when it’s charged by a corotron wire. The print head of the printer then traces this image on paper as it’s passed through the machine. Laser printing was invented in 1969 by Gary Starkweather who sold his patent to Xerox for $6 million dollars.
There are three major types of laser printers:
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Copier vs. Printer
Two major terms used in printing are “copier” and “printer.” Although both do forms of copying, they have distinct differences: copying vs printing copies output onto plain paper while printing copies onto special media such as labels and cards.
Copiers are faster and cheaper than printers. They are small in size and can be stacked together, thus allowing multiple copies to be produced at one time.
Printers are larger, require more space and produce higher quality copies for commercial uses. Not only do they require time to produce a good-quality copy, they also cost a lot more than copiers.
How does it work?
There’s an electrical charge on the corotron wire which is formed by a laser diode that passes through the drum of the printer. The corotron wire then interacts with ions present on the drum, causing them to become an image on paper.
On the other hand, since there’s no electrical charge on plain paper, it is then attracted to the positively charged drum. While in the process of leaving the drum, this image is transferred to paper.
Different colours are obtained by using different diodes that generate different colours.
The Laser Printing Process
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About Laser Printers
The laser printer was invented by Gary Starkweather in 1969 while he was working for a company called Xerox. He sold his invention to Xerox for $6,000,000!
Laser printers are used by businesses and offices mainly because of the quality of their prints. They are also used as high-end printers for personal use.
Originally, laser printers were a lot more expensive than inkjet and dot matrix printers. But prices have remained the same for the past few years since technologies with low costs were invented.
The Performance of Laser Printers
In terms of printing performance, laser printers are also very good! The quality is on par with colour inkjet printers and they produce true colour prints.
They are also known for their longer print lengths. However, not all businesses need 40-page or even 100-page documents. Longer page lengths will only drain the resources of a business faster. The best solution is to use multiple laser printers by connecting them together to make a large network that can print more copies simultaneously. This saves time because the printer does not have to pause every time a single copy is to be printed.
The printing speeds on laser printers are also quick. It takes only a few seconds for a laser printer to print a page.
What makes them unique?
Laser printers are unique because they can print in full colour. They also provide a large number of pages on demand.
They’re also quiet compared to inkjet and dot matrix printers as they do not make any noise when they are in use!
Laser printers can be connected to your computer or network so you can access and send your documents from anywhere through the internet. You can also make copies of files stored on your computer using the hard disk drive of the printer.
Inkjets are the cheapest among printing devices. They are also small and compact, meaning that they can fit in anywhere!
A laser printer is a computer printer that produces a black-and-white image using a laser beam. This technology came about in the early 1970s and has seen many improvements since then, so it’s likely that what we know as today’s laser printers are very different from those used in the 1970s.
A typical laser printer uses a rotating cylindrical lens to focus parallel light beams onto an electrically charged photoconductor drum, which gives off electrons as it is struck by the photons in the light beams, thereby creating a pattern of dots on paper.
A column of electrostatic or electromagnetic drums stores charge until one is selected to write an electronic signal proportional to its surface voltage on paper. The change in the charge pattern, while repositioning of the drum – called a “drum rotation” – creates the image on paper.
A typical laser printer uses one of three types of drums:
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Laser printers originally used normal white computer paper [but they were slow]. Later models use thermal dye transfer printing (D2T2), which is faster than toner-based printing (D2T3). To produce a high-quality image, laser printers must have a high resolution, at least 2,400 pixels per inch (ppi).
In 2000, a new high-performance imaging drum supply system was added to the technology, which increased the drum life by more than 600% and allowed printing speeds up to 80 pages per minute (ppm), and eliminated the need to change the drum before replacing it. Thermal printers typically offer 40 ppm printing speeds.
In addition, thermal printer toner has dramatically improved during the past few years. Earlier models can only print black and white, but many models today have photosensitive elements that allow them to print in color.
The trade-off between cost and print quality is loaded into every laser printer. The obvious compromise is between quality and speed. At the other end of the scale, printers for specialized applications may be built very rugged and reliable, but are much slower than their consumer counterparts.
The laser printer has become a common fixture in nearly every office environment today, thanks to its combination of speed and good-quality font reproduction.
Some laser printers offer an optional fax modem or network interface card to allow them to receive faxes directly, or to be attached to a local area network (LAN), or even transmit in real time over the Internet (print servers). It is not uncommon for some models of these advanced & high quality printers to include email capabilities as well.
The technology that drives today’s laser printers is not quite as revolutionary as it once was. Today’s printers use photoreceptor paper, which provides a flat accurate image that can be easily printed in black-and-white or in full color using toner and ink. Later models, such as those capable of printing by means of a short light beam (called “on-demand printing”), can also print halftone images, which are more realistic looking.
The emerging field of e-laser printers has brought about even more changes. These can print characters in many colors, and are sometimes called “electronic laser printers” or “laser-e”. Laser-e printers have only recently been introduced to the market, but early models can be used to create static images from scanned information (such as barcodes) or to rapidly print out complex images.
Not all manufacturers use the same term for laser printers; some use the term laser printer, while others call them laser plotters. What the same manufacturer calls a laser printer though may vary according to which model line is being sold and on what platform it is sold.
Laser printers operate based on the writing of a graphic image using a laser. The graphic is written by addressing each of the dots which form the graphic. The addressing is then used to create an electric pulse, which is then applied to the photoconductor. This electric pulse causes the surface of the photoconductor to change its electrical resistance; this can then be interpreted as an on or off signal.
Some black-and-white laser printers can create grayscale images by applying three separate toners with different electrostatic charge levels, and red, green, and blue color toners for color printing (see inkjet printer). The toners are bound to a plastic resin-coated paper by fusing the plastic resin to the paper, creating a permanent image. This process works much like an ink jet printer (as the name suggests), except that it applies toner instead of ink to the page.
Inkjet printers work in a completely different manner and do not use a laser as their source of light. The most basic inkjet printers simply squirt droplets of ink on the paper from an ink reservoir, which can be refilled when necessary or replaced with new cartridges. More advanced models are able to combine two or more colors into one droplet, effectively halving the number of nozzles required for printing while maintaining high quality.
Most printers use a technology called raster imaging, which is the traditional technology used in printers. The printed material may be paper or another material such as transparency or overhead projector presentation film. An intermediate image is created in a raster output processor (ROP) or similar devices, and then sent to the print engine. The actual mechanism of the printer to deposit ink onto paper is generally called a “printhead” and can be moved across the paper path by mechanical stepper motors or piezoelectric actuators, depending on the printer design.
Some inkjet printers use thermal printheads that heat up to produce droplets of ink from thermal cartridges/pens. Some laser printers use “thermal transfer” printheads, which have a heating element in the printhead itself. The advantage of this approach is that it allows printing on transparent and thin materials, such as photographic paper.
In earlier printers, the ink was pushed through an ink cartridge using pumps. Now printers are designed so that the ink is pulled out of the cartridge by capillary action to the print head. This design makes for much less leakage of ink. In addition, new cartridges can be sealed until they are filled with ink (cartridge sealing).
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Who should use a laser printer
This is a great question with a complicated answer. Laser printers can be an excellent way to save money! But it’s important to weigh the pros and cons of using one, as they may not be the best choice for everyone. So before you make your decision, ask yourself these questions:
If you answered yes to any of these questions, then you might want to stick with an inkjet printer. If you answered no, then consider a good quality laser printer.
If you answered yes to the first question, then there are two great choices: an inkjet printer and a laser printer. Inkjet printers use inexpensive cartridges and generally cost less. They are very light on electricity usage, which is good because they use toner ink that requires drying time before it can be printed on paper.
Because of this, a laser printer will be more expensive in the short run, but will save you money over time by not having to replace expensive ink cartridges or paper stock. Laser printers also produce much faster printing times.
If you answered yes to the second question, then it’s time to look at what types of laser printers are available. Depending on what type of material you need to print, there may only be one best choice for you or there may be many good choices for you.
If you answered yes to the third question, then it’s important to know about the two basic types of quality that printers produce: “Draft” and “High density”. Draft is the lowest level of quality and high density is the highest. Draft quality is very cheap, but it won’t last long. High quality printers will not only last longer but print less expensively. A typical high-quality laser printer will print for around $500-$1000 and can last for two or three years before having to be replaced.
If you answered yes to the fourth question, then you are concerned about something that should not be a concern-electrical hazards near laser printers. The amount of electricity used by laser printers is small compared to the amount used by any household electrical appliance.
What most people are concerned about is “static electricity”. Static electricity occurs when molecules in the air rub one another and build up an electrical charge. This charge can be released suddenly when you touch a piece of metal, creating a spark that might short out your printer and damage it.
There are two ways around this problem:
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WHAT TO USE:
Laser printers are a type of inkjet printer that use toner, which is a dry chemical powder with dye that is melted and fused to the paper by the laser beam. Laser printers produce high quality text and graphics, and usually have much lower running costs than inkjet.
Some problems with laser printing are high cost of supplies, printing speed isn’t as fast as an ink jet printer, and more dust from the toner being heated to melting point. The best solutions for these problems though are using toner saving modes on a laser printer or replacing the toner cartridge before it runs out so you can print in full color when you need it most.
Laser printers are also known as “electrophotographic printers” because they use electrified photoreceptor (photography) paper to create an electrostatic latent image (a magnetic charge). The image is then transferred onto plain paper via a laser. Laser printers are faster than ink-jet and produce much higher quality images. They also print on transparencies and legal-sized paper.
They are relatively slow compared to ink-jet due to the fact that the toner cartridge must first be electrified before being fused to the page by a laser.
A laser printer, like any other printer, takes input from a computer or another electronic device and the produces an output. The difference between a laser printer and an inkjet printer is that it uses light to form images on paper while inkjet printers use ink.
A laser printer uses a process called electrophotography to create images. The printer has an image drum that rotates at a speed of several thousand revolutions per minute. This image drum is charged so that it can attract toner (a powdery substance) and toner cartridges supply the toner in liquid form to the drum. The paper is held on a roller and moves at a set pace while the image drum rotates beneath it.
Using another set of electrostatic charges, the printer locates where on the page it needs to print and holds each spot in place as long as it takes for all the dots to be printed on the paper. After the print is completed on a spot, the laser light turns off and the roller continues to move until it is ready to print another spot.
The paper moves from the feeder rollers and onto a transfer belt. The printer detects this movement and adjusts its laser beam so that when it touches the paper at an appropriate point, it will transfer some of its image. The toner then sticks to the paper while a special clear coating prevents light from being reflected back into the printer.
The page is separated into units called dots, which are all equal in size no matter where they are on the page. The printer converts the dots into an image in a process called dithering. The printer’s control panel also allows the user to change the amount of dithering used in the print, making it appear darker or lighter.
The paper makes one complete revolution around the rollers and exits through a paper exit slot at the right-hand side of the printer. The light reflected by this paper is directed into a beam-splitter prism.
Some of this light is diverted upwards through a glass plate, while some is redirected downwards, using lenses or mirrors to split it up into four colours: cyan (blue), magenta (purple), yellow and black. The light is then directed through special lenses that focus the light. These lenses are called collimating lenses. The laser beam is highly focused. It goes through the photosensitive drum, where it causes the charge of the surface to either move closer or farther away from it, creating an electrostatic latent image on the drum’s surface.
This latent image is then visible under ultraviolet light, which is used to expose it onto a sheet of photoreceptor material (photoconductor). This photoreceptor can then be charged so that when paper passes over it, other parts of the latent image will attract toner, and this will form a materialized, visible image on paper. The halftone images are created by exposing the photoreceptor to light of different strengths, thereby controlling how much toner is attracted to each part of the photoreceptor.
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Step by step information on how a laser printer works:
A laser printer works in a way very similar to an ink jet printer, but instead of using ink as ink jet printers do, it uses dry powder. The powder is confined in a drum inside the printer and when electrical energy is applied to it, it turns into a gas and then gets deposited onto the paper. This technology is called electrophotography. A laser beam shines through an image drum that has a coating of light sensitive material on it. When the drum is charged, it attracts toner particles, which stick to the drum and leave a visible image on paper.
The printer has a series of vacuum tubes that supply printer heads: the pickup assembly and a photo-conductive ribbon that scans the paper. The laser beam strikes an image on the drum, creating vanishing points. A special mirror reflects this laser beam out of the top of the printer head and along with four mirrors directs it to a point where it hits an E-beam coated ribbon. The E-beam is similar to infrared light but with higher speed. As the laser beam passes through the drum, it deflects the E-beam just enough to make it bounce off of an image on the drum.
The E-beam travels along a photo-conductive ribbon until it hits a photosensitive material contained in a photosensitive drum. When this material is charged by the E-beam, it develops an electrostatic latent image on the drums surface. This latent image is then visible under ultraviolet light, which is used to expose it onto a sheet of photoreceptor material (photoconductor). This photoreceptor can then be charged so that when paper passes over it, other parts of the latent image will attract toner particles, and this will form a materialized visible image on paper. The halftone images are created by exposing the photoreceptor to light of different strengths, thereby controlling how much toner is attracted to each part on the photoreceptor.
The printer uses a controlled explosion, called a flash, in a krytron; this produces an instantaneous pulse of energy which generates electrons. The electrons are then focused into the charging electrode in the laser printing unit and they cause an electric current to flow through a wire located on top of the image drum. The area covered by this wire heats up and a spot appears on its surface.
The toner powder placed on top of this area then adheres to it. As the toner builds up, it is pressed down by the weight of more toner on top of it and a sharp image is formed. As toner drops out from this area, the remaining powder is pressed down and either absorbed or transferred to a perforation pad. The perforation pad removes the paper from between the drum and the sheet while leaving a negative image on it.
The printer may be used in several modes: continuous or intermittent printing, combining types of printing into one job or branching off one job into another. The first method includes either offset printing or direct digital printing (DDP). The Incentive Value Calculator (IVC) gives a total price for the printer. IVC uses the ANSI/ISO 2788-2 equation to calculate the cost per page of printing.
The high-speed machine or High Speed printer does not require a computer, and the program is loaded into an optical editor (or laser printer controller). The program uses a high contrast to print text and graphics, such as color charts or maps to produce color output. The UV exposure can also be used in combination with the ink jet printers to provide color printing that is not possible with conventional offset printing machines, such as full-color prints on colored paper.
The machine prints on rolls of paper, because it uses a continuous process. The paper rolls through the printer on a shaft that is mounted vertically.
The processor is the computer that controls all of the functions in the printer. It has speed and quality (SPQ) of 300 lines per minute, which means 300 lines of text can be printed in 1 minute. The print resolution is 400 dpi, or dots per inch; this term refers to how many dots can be printed on a page. A higher number results in finer detail in an image, but it takes more time for printing and it uses more toner. The input/output (I/O) bandwidth is 21 MB/second. The language of printing is PostScript.
The laser printer uses a laser to make an electrical current into a beam that can be imaged onto a paper, plastic, cloth, or other imaging media. The electrical current excites the medium, creating either colored light or black ink depending upon how the medium was exposed to the beam. An image on the material is created by either exposing it to red light or green light or by exposing it to black light and then exposing it again with UV light (or blue). If exposed with red and blue wavelengths of light, for example, if only yellow toner is used for targeting, dark yellow inks will appear on the material being printed. If yellow toner is used, the material will appear a light yellow.
A printer having a resolution of 600 dpi (dots per inch) prints 600 dots in one linear inch of paper motion. A printer having a 1200 dpi resolution (dots per inch) prints 1200 dots in one linear inch of paper motion. However, if the printer has a higher dpi resolution, it can use less ink to recreate an image on paper. In other words, the margin for error is less with higher dpi resolutions. DPI resolution is generally expressed in dots per inch (dpi) or lines per inch (lpi). Text and graphics printed at 300 dpi will require three times more space than those printed at 600 dpi to achieve the same accuracy.
There are a few other issues to consider when choosing a DPI resolution. Most modern printers have print speeds ranging from 25-40ppm (pages per minute), which means it takes one page 30 seconds to print. However, most printers have a buffer time before they can print the first page of two-sided documents. This buffer time is generally between 10-15 seconds. The reason for this buffer is that the system takes time to warm up and calibrate itself before printing can begin.
Most printers also have a default setting of an 8×11 paper size, which means they take 8 seconds to print one page of this standard size paper. The first page of a multi-page job can take longer than the subsequent pages, because they haven’t yet entered the buffer memory, and therefore require more time to print.
The laser printer uses a process called electrophotography to create images. The printer has an image drum that rotates at a speed of several thousand revolutions per minute. The rotation of the drum produces an image that is visible when it is viewed through a special viewing window. This process can be compared to making a photograph with a camera.
The printer has a series of vacuum tubes that supply printer heads: the pickup assembly, and a photo-conductive ribbon which scans the paper. The laser beam strikes an image on the drum, creating vanishing points. A special mirror reflects this laser beam out of the top of the printer head and along four mirrors directs it to points on or near where it will hit an E-beam coated ribbon.
The E-beam is similar to infrared light but with higher speed. As the laser beam passes through the drum, it deflects the E-beam slightly, making it bounce off of an image on the drum. The E-beam travels along a photo-conductive ribbon until it hits a photosensitive material contained in a photosensitive drum. When this material is charged by the E-beam, it develops an electrostatic latent image on the drums surface. This latent image is then visible under ultraviolet light.
This latent image is then visible under ultraviolet light, which is used to expose it onto a sheet of photoreceptor material (photoconductor). This photoreceptor can then be charged so that when paper passes over it, other parts of the latent image will attract toner, and this will form a materialized visible image on paper. The halftone images are created by exposing the photoreceptor to light of different strengths, thereby controlling how much toner is attracted to each part of the photoreceptor.
The electronic circuit boards in a laser printer can include:
Laser printers can also be classified by their generation, which describes how they create an image and what kind of memory they have for storing instructions. Newer generations tend to cost more than older ones and print faster.
Some of the other components in a laser printer are:
A laser printer uses a controlled explosion, called a flash, in a krytron; this produces an instantaneous pulse of energy which generates electrons. The electrons are then focused into the charging electrode in the laser printing unit and they cause an electric current to flow through a wire located on top of the image drum. The area covered by this wire heats up and a spot appears on its surface. The toner powder placed on top of this area then adheres to it. As the toner builds up, it is pressed down by the weight of more toner on top of it and a sharp image is formed. As toner drops out from this area, the remaining powder is pressed down and either absorbed or transferred to a perforation pad. The perforation pad removes the paper from between the drum and the sheet while leaving a negative image on it.
The various components of a laser printer function through injection of electrical energy into material at selected points on a rotating drum which is called an electrostatic latent image. This latent image is then visible under ultraviolet light, which is used to expose it onto a sheet of photoreceptor material (photoconductor).
This photoreceptor can then be charged so that when paper passes over it, other parts of the latent image will attract toner, and this will form a materialized visible image on paper. The halftone images are created by exposing the photoreceptor to light of different strengths, thereby controlling how much toner is attracted to each part of the photoreceptor.