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Printers are peripheral devices, which connect to computer by an interface or data communication cable that allow obtaining a hard copy of files stored on the hard disk. Depending on the quality, speed and frequency of printouts, printers can broadly be classified into dot matrix, line matrix, inkjet and laser printers. Today, dot matrix printers are still used by companies and individuals who require a lot of printing jobs to be accomplished in a single day, without the necessity of colour outputs. The prices of inkjet printers have come down considerably in the last three years and hence these peripherals can be commonly found in households, small and medium sized design studios and printing departments. Laser printers are still relatively expensive and can only be afforded by large organizations and print publishing houses, who can look into long term investments and for whom, accuracy and image detail is of paramount importance. How much and where to print is controlled by the electronics drive inside the printer and driver software that is usually supplied with the printer. Before start using the printer, the computer has to be notified the existence of the printer. The installation diskettes provided with the printer establish this and also load necessary drivers that operating system can recognize, so that it can configure the printer properly, by identifying that make and model. Many operating systems ship with lot of default printer drivers and it may recognize printers accordingly. It is advisable to install the appropriate drivers from the diskette provided at the time of purchase or download one from the manufacturer's website to enjoy the maximum features of the printer. Printers are connected to computers via parallel port or in newer computers via USB port. USB is a much faster communication port that allows configuring devices even when the computer is on. A typical printer will have the components such as drive electronics and carriage, a tray to place paper for printing, print cartridges that rest in cradles in which the cartridges fit into, paper width and length adjuster which helps in stacking up the paper sheets so the printer can roll out one paper at a time, power and resume buttons, communications port to connect to a computer. When a print command is executed from the computer, data in the form of text, graphics and the format in which to print them is located into memory and sent to the printer. The controller inside the printer takes shock of this information and directs the printer head to move accordingly over the paper. A printer head is small, and therefore to print a complete line on an A4 sized sheet has to move across the paper, printing data on its way. In one pass, the printer most probably will not print a decipherable line of text. Only on the second pass will the line appear readable. An universal directional printer suffers from the disadvantage that after it prints the first half of the line, it has to travel all the way back to the start of the line and then print the bottom half of the line. A bi-directional printer on the other hand can start from either sides of the paper. Before the printing starts, the printer has to load the paper. If there is no paper, a warning will be issued like a light blinking and the printing will not proceed, although the command has already been executed and is scheduled as a waiting task in the printer memory. As soon as the paper is fed and the resume button is pressed, a set of wheels rolls up the paper over a drum that presses the paper over it firmly. A printer head moves across this paper and shoots out jets of ink from tiny nozzles on the cartridge. Ink is heated inside the printer head, which causes it to form a bubble thus forcing out the appropriate amount of ink onto the paper. With usage, ink deposits cling onto the print cartridges along with paper fibres, which may result in smudging and bleeding of colours on printed documents of photography. Laser printers employ a different technology when printing. A light beam scans across the breadth of a photosensitive drum, which is initially electrically charged. Based on where and when light is directed on this drum, toners or small ink modules are attracted to the paper, which gets fused instantly. That is why when a printed document comes out of a laser printer; it is not needed to blow or dry the ink, which would be the case in an inkjet printer. Try to use quality paper while printing, especially when the printer manual recommends it. This will reduce the frequency of fibre like stands of paper getting stuck under the printer cartridges. Do not plug the power cable off the printer unnecessarily as this may shorten the life of the printer considerably. Open the flap of the printer and use a moderate powered vacuum cleaner to suck up dust and debris. Perform automatic printer cleaning, which will help re-establish proper alignment of printer heads. The printer array was earlier too crowded with a bandwagon of heavyweight, bulky and noise models around. Now times and requirements have changed and so have the models and their performance. There have been character printers, which printed a character at a time. There have been line printers and page printers too. There are now several major printer technologies available. These can be categorized into two groups with several types in each Impact and Non-impact. The mechanism of impact printers have involves touching of the paper in order to create an image. The two main impact technologies are; Dot Matrix and Character. Dot Matrix printer prints in a pattern of dots and hence the name. Being a dot printer, it can print in any language and make very effective use of graphics. Some drawbacks of this model are that it is very noisy and low, can only be used in short stretches and produces a rather poor quality of print. Character printer can be called computerized typewriter. This machine has a ball or series of bars with actual characters, letters and numbers embossed on the surface. The appropriate character is struck against the ink ribbon, transferring the character’s image to the paper. Character printers are fast and sharp for basic text, but very limited for any other use. Non-impact printers do not touch the paper when creating an image. Inkjets and Lasers belong to this family. Inkjet printers use a series of nozzles to spray drops of ink directly on paper. This non-impact model fires ink-drops on the paper by using an electrostatic field. Its print head has a nozzle, which fires a jet of electrically charged ink at the paper thus forming characters. This firing happens silently. Laser printers use dry ink called toner, static electricity, and heat to place and bond the ink onto the paper. The print pattern followed is not that of a matrix of dots and hence come out neat and clear. The laser models are better performing of all and hence the most preferred in the market. Solid Ink printers contain sticks of wax-like ink that are melted and applied to the paper. The ink then hardens in place. Thermal Wax printers are something of a hybrid of dye-sublimation and solid ink technologies. They use a ribbon with alternating CMYK colour brands. The ribbon passes in front of a print head that has a series of tiny heated pins. The pins cause the wax to melt and adhere to the paper, where it hardens in place. Thermal Auto-chrome Printers have the colour in the paper instead of in the printer. There are three layers cyan, magenta and yellow in the paper, and each layer is activated by the application of a specific amount of heat. The print head has a heating element that can vary in temperature. The print head passes over the paper three times, providing the appropriate temperature for each colour layers as needed. Dye Sublimation printers have a long roll of transparent film that looks like sheets of red, blue, yellow and grey colour cellophane stuck together end to end. In this film, solid dyes are embedded which correspond to the four basic colours used in printing; cyan, magenta, yellow and black. A heating element is used by the print head that varies in temperature, depending on the amount of a particular colour that needs to be applied. The dyes vaporized and infuse the glossy surface of the paper before they return to solid form. When each of the basic colours gradually builds the image on the paper, the pass is said to be complete. Of these, inkjet and laser printers are considered the popular technologies. Installing a printer is all about buying the right cable, plugging it into the proper ports on the computer and printer. It is also about getting the right cartridge and installing the right driver. A printer attaches to a computer via the computer’s parallel port, which is also called a CENTRONICS port. The printer cable should match the printer and computer ports. Turn off the printer and the computer and plug the printer cable into the proper port on the computer. Some computers have 25 pin female serial ports, as well as 25 pin parallel ports, so be sure to plug the cable into the parallel port. The parallel port on the computer is a female connection. After this, each cable is plugged in securely. Tighten the screws or snap wire connectors on either side of the connector. When printers do not readily have an ink cartridge or toner cartridge in it, then the manufacturer’s instructions are needed to follow for installing the right cartridges. Open the printer window by selecting the printer’s shortcut from the start menus settings group. Click “Add printer” icon in the printer window to launch “Add new printer” wizard. Click “Next” button to begin the installation process. Select “Local printer” radio button and click “Next” button to continue. Scroll down in the manufacturers list and select the manufacturer of the printer. This causes the printer list to display the printer models for which Windows 98 include drivers. Select the model of the printer and click next to continue. If the printer is not listed or if it is needed to install drivers from another source, click “Have disk” button and browse to the location of the driver files. Select the port to which the printer is connected in the available ports list. Click “Next” to continue. Enter a name by which the printer will be known on the local machine. By default, the system uses the name associated with the printer driver, but this can be changed. If this is the first printer driver installed on the computer, the wizard makes it the default printer. If other printer drivers are installed, it is needed to specify whether the new printer should be the default. Make sure the printer installation exercise is a success. Print out a test sheet of paper. After it prints out, it asks whether it printed properly. Allow time before answering, “Yes” or “No”. Dot Matrix printers mostly adorn the reservation counter offices or government organizations, in places where the workload for a printer is immense and where people don’t want to invest more in the machine. In short the output of this machine is invoices, tickets, order forms, bills, memos etc. These are considered faster than lasers and inkjets where documents need to be printed in multiples. The dot matrix printer has a print head made up of very thin pins which prints in a pattern of dots and hence the name. Being a dot printer it is able to print in any language and can make very effective use of graphics. Sometimes it is too noisy. When the dot matrix printer receives data of a document, through a cable, as a command, it creates a buffer to store the same. This data is then translated into a form that the printer can use. The processor takes one line to type, to decide upon the best pattern of dots to print. Activated by the processor, the pins in the pinhead move on the ink ribbon and being printing. Heat becomes a problem when the speed of the pins and their rapid firing causes friction with in the print head, but the heat sink acts like a radiator and the airflow cools these small pieces of metal. There is a permanent magnet on the top end of every pinhead that holds it away from the ribbon and paper when it isn’t needed. The more the pins, the tinier the dots, the better the quality, but all this results in lesser speed. Check for any loose cables, wires, or screws. Check if the head carriage is loose from the sides. With a cloth or paper wiper, clean the main guide rail. Do not use oil on the rail, as the carriage might not have free movement from side to side. Vacuum any of the paper dust that may be visible. Change ribbons as soon as they begin to fade. Readjust the platen gap forms thickness and close the cover. Buy a printer with a straight paper path to avoid jamming. Wide-format printers are available for offices that print onto 11” x 14” computer paper. Dot Matrix printer is good for bulk printing. When loading forms such as invoices or anything to tear at the perforations, use either the rear or bottom tractor to rip at the perforations. Dot Matrix printer range starts from 6,000 Rupees to 2,00,000 Rupees. The size and features affect the price. A dot matrix can either have 9 metal pins or 24 metal pins. The print resolution of printout by a 24 pins printer is higher compared to the output from a 9 pins printer. Since the introduction in the latter half of the 1980s, inkjets printers have grown in popularity and performance while dropping significantly in prices. An inkjet is any printer that places extremely small droplets of ink onto paper to create an image. If the dots are extremely small usually between 50 and 60 microns in diameter, the dots are positioned very precisely with resolution of up to 1440 x 720 ‘Dots Per Inch’ (DPI). The dots can have different colours combined together to create photo-quality images. Inkjet printers can add colour printing capabilities to home or office computer system at a low cost. They are ideal for low-end, low-volume colour printing. A standard copier paper doesn’t provide as crisp and bright an image as paper made for an inkjet printer. The two main factors that affect image quality on the inkjet printer are brightness and absorption. The brightness of a paper is normally determined by how rough the surface of the paper is. Any paper that is listed as being bright is generally a smoother than-normal paper. Another key factor in image quality is absorption. The paper should not absorb too much ink, or else, the page will be fuzzy. High-quality inkjet paper is coated with a waxy film that keeps the ink on the surface of the paper. Coated paper normally yields a dramatically better print than other paper. Inkjets are capable of printing on a variety of media. Commercial inkjet printers sometimes spray directly on an item like labels. For consumer use, there are a number of specialty papers, ranging from adhesive-backed labels or stickers to business cards and brochures. Parts of a typical inkjet printer include print head assembly, paper feed assembly, power supply, control circuitry, and interface ports. Print head assembly includes print head, print head stepper motor, ink cartridges, belt and stabilizer bar. Print head contains a series of nozzles that spray the ink. Ink cartridges come in various combinations, depending on the manufactures and model of the printer. Print head stepper motor moves the print head assembly back and forth across the paper. Belt attaches print head assembly to the stepper motor. Stabilizer bar keeps a check on the movement. Paper feed assembly includes paper tray or feeder, rollers, and paper feed stepper motor. Most inkjet printers have a tray that loads the paper into. Some printers have a feeder. A set of rollers pulls the paper in from the tray or feeder and advanced the paper for another pass. Paper feed stepper motor powers the rollers to move the paper in the precise increment for a continuous image. Most printers today have a standard power supply. A small but sophisticated amount of circuitry is built into the printer to control all the mechanical aspects of operation, as well as decipher the information sent to the printer from the computer. The most popular way of connecting a printer is through parallel port, but a large number of newer printers use USB ports. Laser printers are the fastest printers developed till date. Laser printers deliver excellent quality output and control five different operations at the same time like, interpret signals from the computer, translate those signals into instructions to control the firing and movement of a laser beam, manipulate paper movement, sensible the paper so that it will accept the black toner that makes up the image, and fuse that image to the paper. Laser printers use a technology similar to the one used in photocopiers. A laser beam is focused on a photoelectric belt or drum, creating an electrical charge. In the case of colour laser printer, this process occurs four times, one each for the cyan, magenta, yellow and black components of the image. Electrostatic charges cause the toners to adhere to the belt. The image is then transferred to a drum that rolls the toners on to the sheet of paper or transparency. Toners are then fused using heat alone, or a heat-pressure combination. Laser printers are fast and do not require any special media. They are very useful in heavy-duty printing. Some newer laser printers use a strip of ‘Light Emitting Diodes’ (LED) to write the page image instead of a single laser. Each dot position has its own dedicated light, which means the printer has one set print resolution. These systems cost less to manufacture than true laser assemblies, but they are believed to produce inferior results. They are typically found only in less expensive printers. Laser printers work on a basic principle, which is static electricity. The major element of this system is the photoreceptor, which is typical revolving drum or cylinder. This drum assembly is made out of highly photoconductive material that is discharged by light photons. The drum initially receives a total positive charge by the charge corona wire, a wire with an electrical current running through it. Some printers use a charged roller instead, on the same principle. When the drum revolves, the laser, which is reflected across the surface, actually etches the letters and images to be printed, as a pattern of electrical charges an electrostatic image. Once the pattern is set, the printer coats the drum with positively charged toner. A toner is a fine, black powder and since it has a positive charge, it clings not to the positively charged area but to the discharged areas of the drum. With the powder pattern affixed, the drum rolls over a sheet of paper, which is moving along a belt below. Before the paper rolls under the drum, the charged roller gives a negative charge to it. This charge is stronger than the negative charge of the electrostatic image, so the paper can pull the toner powder away. Since it is moving at the same speed as the drum, the paper picks up the image pattern exactly. To avoid the paper clinging to the drum, it is discharged immediately after picking up the toner. Finally, when the printer passes the paper through a pair of heated rollers, which is the fuser, the loose toner powder melts, fusing with the fibres in the paper. Then the fuser rolls the paper to the output tray. The fuser heats up the paper and hence pages are always hot when they come out of a laser printer or photocopier. It is the speed that keeps the paper from burning up. Initially, most commercial laser printers were limited to monochrome printing. However, more and more colour laser printers have hit the market recently. Essentially, colour printers work the same way as monochrome printers, except they go through the entire printing process four times; one pass each for cyan, magenta, yellow and black. By combining these four colours of toner varying proportions, one can generate a full spectrum of colour. We would list the main advantage of laser printers as speed, precision and economy. A laser can move very quickly, so it can write with much greater speed than an inkjet. Also, as the laser beam has an unvarying diameter, it can draw more precisely, without spilling any excess ink. Though laser printers tend to be more expensive than inkjet printers, it still doesn’t coast as much to keep them running. The toner powder is cheap and lasts a long time, while expensive ink cartridges can be used up very quickly. In most models, this mechanical efficiency is complemented by advanced processing efficiency. After dot matrix and inkjet came the laser printer. Although little on the expensive side, they have low running costs with quality printing. They are, reportedly, the current favourite printing technology in the market. Laser printers are the fastest machines developed till date in their category. They deliver excellent quality output and control five different operations at the same time. Interpret signals from a computer. Translate them into instructions to control the firing and movement of a laser beam. Manipulate paper movement. Sensitise the paper so that it will accept the black toner that makes the image. Fuse the image to the paper. A laser can move very quickly and can therefore write with much greater speed than an inkjet. Also, since the laser beam has an unvarying diameter, it can draw more precisely without spilling any excess ink. Though laser printers tend to be more expensive than inkjet printers, their cost is still not prohibitive. Even the maintenance cost is not that high. The toner powder is cheap and long lasting while ink cartridges are expensive and get used up very quickly. In most models, this mechanical efficiency is complemented by advanced processing efficiency. Laser printers use tiny jets of ink to put an image on paper. The primary principal at work is static electricity, which is simply an electrical charge built-up on an insulated object such as a balloon. Since oppositely charged atoms are attracted to each other, objects with opposite static electricity fields cling together. The core component of this system is the photoreceptor, a revolving drum or a cylinder. This drum assembly is made out of highly photoconductive material that is discharged by light photons. Initially, the drum is given a total positive charge through a wire with an electrical current running though it called corona wire. As the drum revolves, the printer shines a tiny laser beam across the surface to discharge certain points. In this way, the laser draws the images to be printed as a pattern of electrical charges, an electrostatic image. The system can also work with the charges reversed, a positive electrostatic image on a negative background. The printer then coats the drum with positively charged toner, a fine, and black power. Since it has positive charge, the toner clings only to the negatively discharged areas. With the power pattern affixed, the drum rolls over a sheet of paper moving along a belt below after it is given a negative charge. Since this charge is stronger than the negative charge of the electrostatic image, the paper pulls the powder away. Finally, the printer passes the paper through a pair of heated rollers, which melts the toner. The fuser rolls the paper to the output tray giving a finished page. The fuser also heats up the paper itself, of course, which is why pages are always hot when they come out of a laser printer or photocopier. But what keeps the paper from burning up is the speed at which it passes through the rollers. After depositing the toner on paper, the drum surface passes through the discharge lamp. This bright light exposes the entire photoreceptor surface, erasing the electrical image. The drum surface then passes the charged corona wire, which replies the positive charge. Conceptually, this is all there is to laser printers. Of course, actually bringing everything together is a lot more complex. The printer needs to receive the page data to put everything on paper. This is the job of the printer controller, which talks to the computer through a communications port. In an office, a laser printer will probably be connected to several host computers for multiple users. The controller handles each one separately and this ability to handle several jobs at once is one of the reasons why laser printers are so popular. For the controller and the host computer to communicate, they need to speak the same page description language. In earlier printers, the computer sent a special sort of text file and a simple code giving the printer some basic formatting data. Since these printers had only a few fonts, this was a very straightforward process. But there are hundreds of fonts being used today and the printer needs to speak a more advanced language. The primary printer languages these days are PCL, SPL (Samsung Printer Language) and Adobe’s PostScript. They describe the page in vector form, that is, mathematical values of geometric shapes rather than as a series of dots. Some printers use a ‘Graphical Device Interface’ (GDI) format, where the computer creates the dot array itself, so the controller has to only send dot instructions. But in most laser printers, the controller must organize all the data it receives from the host computer. This includes what paper to use, how to format the page, and how to handle the font. Very few companies have complete vertical integration in laser printers. Thus, canon makes engines that many other brands use. However, Samsung is among the few companies that manufacture all components from RISC processor to toner assembly to engines in-house. A laser can move quickly, so it can ‘write’ with much greater speed than an inkjet. The laser beam has an unvarying diameter it can draw more precisely, without spilling any excess ink. Cost of toner powder is cheap compared to ink cartridges hence running cost is law. Installing a printer is a breeze. Most of the problems are likely to reside within a system setting such as bi-directional parallel port setting in the BIOS. One of the vital elements in a laser printer is the toner cartridge. Toner is actually an electrically charged powder with two main ingredients: pigment and plastic. The role of the pigment comprises of providing the colouring that fills in the text and images. This pigment is blended into plastic particles, so that the toner does not melt when it passes through the heat of the fuser. Thus the toner has an edge over liquid ink. It binds to the fibbers in almost any type of paper firmly, which means the text won’t smudge or bleed easily. The powder is stored in the toner hopper, which is a small container built into a removable casing. The toner is gathered from the hopper with the developer unit. The developer is a collection of small, negatively charged magnetic beads. These beads are attached to a rotating metal roller, which moves them through the toner in the toner hopper. The printer may stall sometimes. Relax and check the following to drive out the nightmare. If the printer is not plugged in, maybe someone has accidentally yanked on the printer power cord. Also check the cable connecting the printer to the computer. If the printer is on a parallel port pass through, it is needed to ensure that the device it’s on the pass through with is plugged in and alive. If there is still no success, it is needed to replace the printer cable. The printer driver may be corrupt. Some programs print automatically to default printer; may be the printer is not default. The file may be complicated if an out of memory error is encountered. Get rid of all those tricky fonts. Decrease the graphics on the page. New software or hardware can wreck the system. Check before installing. If it’s an ‘Adobe Acrobat File’ (PDF), and the printer appears bewildered, check print dialog setting in Acrobat. If postscript fonts are being printed on a non-postscript printer then ‘Adobe Type Manger’ (ATM) installation will be required. The printer might run out of memory if too many fonts and graphics are used. Postscript printer should have whatever fonts required in memory and the fonts are either on the printer or downloaded on them before printing. If the fonts are corrupted then the wise thing would be to delete one font, print, delete the next font, print, and so on until the rotten one is found, than reinstall it. Perform a self-test on the printer. This isolates the problem to something other than the operation of the printer itself. Refer to owner’s manual on how to perform a self-test. Check the LPT1 settings in CMOS. If the printer port is not properly identified in CMOS, the printer may play havoc and errors are encountered while printing. Check the User’s Guide to enter CMOS. Once in the Set-up utility, locate the LPT1 settings. The address setting for the LPT1 port should depend on the kind of video card in there. The IRQ setting for the port should be 7 and LPT1 should be enabled in order to print correctly. Rebooting might be required. Ensure that the printer drivers are installed. If the printer, which is being used, is not set as the default printer in Windows or if the printer driver is not installed, unclear character may be printed. To ensure that there is no conflict with another software application, boot the system clean. Once it has been booted clean, type “COPY CONFIG.SYS LPT1” and press Enter key. If the printer is a laser printer and unable to print, type “MODE LPT1 P” and press Enter key before typing the earlier command. For “The printer is off-line or not selected” error message, the printer must be the default printer, ensure printer is on-line, and cable is properly connected. For “Write fault error writing device. Abort, Retry, Ignore, Fail?” error message, ensure that the LPT port is identified correctly in CMOS and the internal and external cables on the printer port are correctly connected. “Cannot locate printer on LPT port” error message occurs if the printer is plugged into the wrong port or the default printer is selected incorrectly. For “Printer is out of paper or not connected” error message, check if the printer has paper and it is not jammed. Get an insight into how exactly the printer rumbles to churn out a print when this command is given. Here it comes one step at a time. At the print command, the software application being worked on sends the data to be printed to the printer driver. The driver interprets the data into a language that the printer can interpret. It also checks if the printer is online and available. The driver sends the data from the computer to the printer via the connection interface. After receiving data, some of the data is safely stored in a buffer, which can range from 512 KB RAM to 16 MB RAM, depending on the model. A printer usually takes a short cleaning cycle to make sure that the print heads are clean if it has been idle for a period of time. As the controlling circuit activates the paper feed stepper motor, it powers-up the rollers, which pushes a paper sheet from the paper tray or the feeder into the printer. This trigger mechanism in the tray or feeder is depressed when there is paper. The printer gives an “Out of paper” alert to the computer if the trigger is not properly pressed. After the paper is fed into the printer and positioned at the start of the page, the print head stepper motor moves the print head assembly across the page with the help of a belt. It’s only for a fraction of a second that the motor pauses, each time the print head sprays dots of ink on the page. It then moves a just a little bit before stopping again. This is so fast that it seems like a continuous motion. A spray of CMYK colours is made in accurate measure to make any and every other colour. At the end of each complete pass, the paper feed stepper motor pushes the paper an extra fraction. This process is continuous till the page is printed. The time a printer takes to print a page depends on the technology of the printer. Factors like the complexity of the page size of images also matter. The print head is parked once the printing is done with. As the completed page is pushed into the output tray, the paper feed stepper motor spins the rollers to a halt. Inks today are fast drying, so that the sheet can be immediately picked up without really making it look gross. Verify that the computer has the right kind of port for the printer, which is selected. While newer models have USB ports, parallel port models are also quite common. For networks, a printer should be able to connect directly to the network and support the protocols, which are used. Seldom it becomes necessary to control printer ports if printouts are not allowed until a certain time. Most access control programs provide some kind of LPT port blocking feature. However, the most difficult problem for most users is to keep a tab of which users have access to which printers. In Windows, printer access is based on INI files can be used to control which printer, the fonts and colours, etc. are available to each user.