Introduction :
The printer is a device that prints text documents and images on paper. It is a peripheral output device. It prints the data that is processed by the computer. Printers are broadly classified in two groups - impact printers and non-impact printers. We can also classify printers on the basis of features like usage of color and fonts.
18.1 Impact Printers
Impact printers are used for printing documents as well as graphics. The working of impact printers is very similar to typewriters. A print head is brought in contact with an ink ribbon. The impact results in printing on paper under the ink ribbon. The dot matrix printer is an example of impact printer.
18.1.1 Dot Matrix Printer
Dot matrix printer uses a matrix of metal pins on the print head to create dots. An ink-soaked ribbon is placed between the paper and the print head. The print head is banged against the ribbon with considerable force. The impact causes imprint of text on the paper. As a result, dot matrix printers are noisy. Dot matrix printers do not produce high quality documents or graphics. Low-quality applications use dot matrix printers. This type of printer is useful in creation of multi-part documents like invoices and receipts. Dot matrix printers are used in carbon copy printing. The number of metal pins in the print head determines the quality of output of a dot matrix printer. The number of metal pins in the dot matrix printers varies from 9 to 24. The best quality dot matrix printers have 24 metal pins. The print head of the dot matrix printer runs repeatedly across the surface of the page being printed. The difference between typewriters and dot-matrix printers is that the typewriter uses a fixed number of alphabetical keys. The dot matrix printers use the matrix of dots to create individual letters or images. The metal pins on the print head of the printer are driven by electromagnets. Dot matrix printers can achieve high resolutions by moving the print head slowly. These printers can be monochrome or color printers. The color printers use a multi-colored striped ink ribbon to print. Dot-matrix printers have a speed of 30 to 550 cps.
18.2 Non-impact Printers
Non-impact Printers are characterized by quiet operation. Non-impact printers do not function by mechanical striking of the print head on the paper. Inkjet and laser printers are types of non-impact printers.
18.2.1 Inkjet Printers
An Inkjet Printer places extremely minute amounts of electrically charged ink on paper to create images or text. The drops of ink are sprayed through a series of nozzles and are around 60 microns in diameter, and are positioned with very high precision. Inkjet printers use color as well as monochrome cartridges. This type of printer provides high quality printing at an affordable price. The power supply of the printer provides the electricity to function. It is usually a part of the printer itself. A circuit board controls the operation of the printer. The circuit board contains the microprocessor and the memory. The interface ports connect the printer to the computer. Most computers connect to the printer through the parallel port. Some printers nowadays use the serial port, USB (Universal Serial Bus) port or Small Computer System Interface (SCSI) port for connecting to the computer.
- Inkjet Printer
The bubble jet printer is a type of inkjet printer. In this type of printer, many resistors are used. These resistors create heat. The heat causes vaporizing of ink. The vaporizing process leads to creation of a bubble in the ink. The creation of the bubble leads to expansion of the ink inside the cartridge and a drop of ink is ejected. This drop of ink is expelled from the print head. The print head has nozzles from which the ink is ejected.
18.2.2 Laser Printer
The laser printer uses a beam of laser for the purpose of printing. The basis of the functioning of the laser printer is the principle of static electricity. Electric charge that accumulates on an insulated object is called static electricity. Objects that have oppositely charged fields of static electricity are attracted to each other. This happens in the same manner as oppositely charged atoms are attracted to each other. The laser printer uses this property to combine ink powder and paper. The laser printer consists of a revolving cylinder that is made up of photoconductive material. The drum is charged with the help of a charging wire called the charge corona wire. This wire has electric current passing through it. The laser printer works in the following manner :
1. The photoconductive drum is given a positive or negative charge by the charge corona wire.
2. When the drum starts to revolve, a laser beam is shone on it. This laser beam consists of light photons. The laser assembly shines the laser beam on a mirror. The beam is then reflected off the mirror. As a result, the drum that is made up of photoconductive material is discharged.
3. The areas of the drum that are touched by the laser develop the opposite charge of the drum.
4. The laser etches figures and characters on the surface of the photoconductive drum. The figures or characters are actually a pattern of electric charges
5. In this case, let us assume that the drum is positively charged. Therefore, the laser-etched areas will be negatively charged.
6. Thereafter, a fine ink powder called toner is sprinkled on the paper. This powder has to be positively charged.
7. As the drum rolls, the toner adheres to the laser-etched area of the drum. It is repelled from the positively charged area of the drum. Thus, the laser pattern is etched on the drum with toner.
8. After this, the drum rolls over a paper. The paper passes along a belt under the drum.
9. The paper is given a negative charge. This negative charge must be stronger than the charge of the laser-etched electric image. This will help the toner to leave the negative area on the drum for the negatively charged paper.
10. The paper is discharged as it moves out. This will prevent the paper from getting attached to the positively charged drum. The paper moves at the same speed as the drum. Otherwise, the image will not be reproduced exactly.
11. The paper is passed through a fuser. This is a pair of heated rollers in the laser printer. As the paper passes through the fuser, the toner melts due to the heat. The toner is thus fixed on the paper.
12. The fuser rolls out the paper to the output tray. The printing process is thus complete.
Working of a Laser Printer
Printouts from laser printers are warm because they pass through the fuser before coming out. However, the paper moves at a very high speed and therefore, it does not get burned. The fuser rollers must be coated with Teflon, which is a non-stick material. This material prevents the collection of toner on the fuser.
18.3 Attributes of a Printer
Characteristics like speed and quality of output differentiate the different printers that we use. Attributes of a printer vary from type to type. We can classify printers on the basis of the following characteristics :
_ Speed -efines the speed at which a printer prints documents. The speed of a printer is measured in characters per second (cps) or pages per minute (ppm). Printer speeds vary widely from type to type. Laser printers can print up to 20 ppm.
_ Dots Per Inch - Specifies the number of pixels or dots of ink that the printer uses while printing an image or document. Dots Per Inch (dpi) is a print setting that the printer uses while transferring an image or document from the computer to paper. A 300 dpi printer will use 300 dots of ink across an inch, vertically as well as horizontally. As a result, a square inch will have 90,000 pixels or dots of ink. The dpi provides a measure of the quality of a printed document or image. A higher dpi measurement indicates a higher quality printer.
18.4 Structure of a Printer
The printer consists of various parts that accept, support, and move the paper during the process of printing. All these parts have to work in co-ordination so that the printer works properly. The different parts of a printer are :
_ Feeder - Accepts the paper and forwards individual sheets as printing progresses.
_ Support - Provides a support for the paper that is loaded in the feeder.
_ Edge Guides - Provides proper adjustment according to the width of the paper. There are two such edge guides. The left guide can be shifted according to the width required.
_ Cover - Covers the printing process. The cover is opened only while replacing ink cartridges.
_ Output Tray - Accepts the paper that comes out.
_ Output Tray Extension - Holds the paper that comes out of the printer.
7.1.1 Advanced Technology Attachment
We can examine the internal parts of the printer if we remove the cover. The parts of the printer that are covered are:
_ Cartridge -ontains the ink for printing.
_ Print Head - Delivers the ink to the page that is being printed.
_ Cover of Cartridge - Provides a cover for the ink cartridge. This cover is removed only when a cartridge has to be replaced.
_ Adjustable Lever - Provides adjustment for distance between print head and paper. This adjustment is essential for avoiding smearing of ink on the paper.
_ Control Panel - Provides control for various actions of the printer. The control panel consist of the following buttons:
_ Power - Turns the printer ON or OFF. If this button is pressed twice when the printer is ON, the printer memory is erased.
_ Paper - ccepts or ejects paper. This button is pressed to resume printing after an error in the process.
_ Ink Level - akes the print head check the ink level. This happens when insufficient ink is detected in the cartridge. If the cartridge is empty, the ink level button makes the print head go to cartridge replacement mode. After the cartridge is replaced, the print head resumes its default mode.
_ Roll Paper - Used for roll paper. This button prints a guideline for cutting the roll paper.
Support
Edge Guides
Output Tray
Cover
Feeder
Output Tray
Extension
Internal Parts of a Printer
The back of the printer has three ports. One port is for connection of the power cord. Another port is for connection of the printer to the USB port of the computer. The third port is to connect the parallel port of the computer to the printer. Most printers connect to the parallel port or USB port of the computer. A few printers also connect to the computer via the serial port.
18.5 Installing a Printer
The printer must be properly connected to the computer. The printer software must be installed correctly. The printer is first connected to the computer through the cables. Then the printer driver is installed.
18.5.1 Connecting the Printer
The printer must be connected properly to the appropriate port on the computer. You must use a good quality cable for the connection
Best practice
1. Study the printer manual thoroughly.
2. Keep some space free around the printer for the purpose of ventilation.
3. Use the IEEE 1284 bi-directional printer cable for connecting printer to the computer.
4. Check the printer manual to ensure that all parts are provided. Some printers are provided with cables.
5. Check the printer for any missing or damaged parts immediately after unpacking.
Precautions
1. Wear an antistatic wristband.
2. Do not connect the printer to the power supply during the process of connecting.
Control Panel
Adjustment
Lever
Cartridge
Cover
Print Head
Hands on exercise
To connect a printer :
1. Find an appropriate, flat place to keep the printer.
2. Take the IEEE 1284 parallel printer cable and study both ends. One of the ends will have 25 pins. Connect this end to the parallel port of the computer.
3. Secure the two hand screws on the cable plug.
4. Connect the other end of the cable to the printer's parallel port socket. If the printer has retaining clips at the parallel port socket, latch the clips securely.
5. Connect the power cord to the printer's power socket.
6. Turn the printer ON.
7. Install the cartridges in the printer according to the directions in the printer manual.
_ Not all printers connect to the parallel port. Some printers also connect to he USB port of the computer. Verify which port connects to the printer before starting the procedure.
18.5.2 Installing the Printer Drivers
The printer driver is the software that controls the operation of the printer. It converts data from the computer to a format that is understood by the printer. The printer driver passes data that is to be printed, to the printer. The printer driver has to be installed for the printer to work. The printer driver can also be replaced if there are later versions of the driver available. We can download printer drivers from the printer manufacturers' site. To install the printer driver after connecting the printer, first turn on the computer. Insert the CD or floppy that comes with the printer. Follow the instructions of the printer manufacturer. This will install the driver automatically.
18.5.3 Configuring the Printer
It is possible to set certain default properties for the printer by configuring it. By configuring a printer, we can avoid the setting of properties for the printer repeatedly.
Hands on exercise
To configure a printer:
1. Select Start _ Settings _ Printers.
2. Right-click the Printer that has to be configured.
3. Select Properties. The Printer Properties dialog box is displayed.
Printer Properties Dialog Box
4. Use the different tabs and options in this screen to configure properties of the printer as required.
18.6 Troubleshooting
There are many problems that can arise during the working of the printer. We have to troubleshoot the printer in order to make it work properly.
Best Practices
1. Read the printer manual thoroughly.
2. Study the safety instructions in the manual.
3. Try printing after connecting the printer to another computer.
4. Try printing a document after replacing the ink cartridge. If the printing is faulty even after replacing the cartridge, it is almost certain that the printer is at fault.
Precautions
1. Wear an antistatic wristband.
2. Disconnect the printer from the power supply.
18.6.1 General Troubleshooting
The printer can stop functioning because of a number of reasons. The computer may not be recognizing the printer or the printer settings may be incorrect.
1. If the printer is displaying flashing lights, refer to the printer manual. The problem that is causing the flashing lights will be explained in the manual.
2. Check if the printer is getting power supply by checking the power display on the printer.
3. Check whether paper that is loaded in the printer is properly placed and is not jammed. Adjust the edge guides of the printer if necessary.
4. Find out if the cartridge in the printer is new or used. If the cartridge is new, ensure that the protective plastic layer on the cartridge has been removed.
5. Check the cable connections of the printer.
6. Run the printer self-test. The printer self-test varies from model to model. Refer the instructional manual of the printer to run the self-test. If the printer fails the self-test, the printer has a problem.
7. Check if the print head is moving. A stationary print head could be the result of a failed transport motor.
8. If the printer passes the self-test, print a test page. If the test page does not print properly, the problem is due to an improper connection between the computer and printer.
9. If the test page prints properly, the problem may be caused due to improper configuration. The output may be directed to the wrong port.
10. Connect the printer to another computer to see if it works.
11. If there are any other parallel devices connected to the computer, turn off those devices to find out if they are causing the problem.
12. Restart the printer and try to operate it. This step can help repair mistakes in internal settings of the printer.
13. Go to the CMOS settings of the computer and verify that the parallel port is installed and working properly.
14. In the BIOS settings of the computer, check the parallel mode. Ensure that the printer is not set to ECP mode. This is because the ECP mode is not suitable to the working of many printers.
15. In the BIOS settings, check the parallel port IRQ. It is preferable to set the IRQ to 7. The sound card of the computer generally uses the IRQ 5. As a result, there can be a conflict between the printer and sound card.
16. Printers that require bi-directional communication need to have the parallel port enabled accordingly. We can do this by setting the parallel port mode to EPP (Enhanced Parallel Port) in the BIOS settings.
17. Check the DIP switches. The DIP switch is a group of switches that sets the configuration for the computer. It is used in place of the jumpers. By checking the DIP switch settings, we can ensure that the configuration of the printer is not faulty.
18.6.2 Printer Driver does not Function Properly
The printer driver can cause many printing problems. These problems are very difficult to detect and trace to the printer driver. This is because the printer driver is very complex software. A problematic printer driver can cause some fonts or formats to cause errors while printing, while others work fine. Some of the possible symptoms of a problem with the printer driver are :
_ Appearance of black boxes all over the printout.
_ Formation of nonsensical characters in the printout.
_ The application crashes as the printing progresses.
_ Missing characters or lines in a printout.
1. Update the printer driver. For this, contact the printer manufacturer or download the driver from their site.
2. If an updated driver is not available, try to find a printer driver that is compatible with the printer.
3. Install the new printer driver.
18.6.3 Troubleshooting Dot Matrix Printers
Dot matrix printers are not widely used presently. However, they are essential in applications that require carbon-copy printing. These printers are not very complicated and are easy to troubleshoot.
Appearance of White Lines in Printouts
A very common problem with dot matrix printers is the formation of white lines in printouts. These lines are mostly horizontal and occur between lines of text or images. This problem by and large occurs due to a problem in the print head.
1. Check the print head to see if all the pins are working properly.
2. Check the print head ribbon. It must be tightly wound to the print head.
3. Ensure that the print ribbon is in good condition.
4. Collection of residue on the print head can lead to printing problems. Clean the print head with alcohol.
5. If none of the above steps helps, replace the print head.
The Carriage of the Printer is Moving, but Pages are Blank
If the carriage of the printer is moving and the printing is not taking place, it is mostly caused by the print head or the ink ribbon.
1. Check the ink ribbon to see if it is dry.
2. If the ink ribbon is fine, check if the print head is striking the ribbon.
3. Check if the printer ribbon is being advanced every time the print head returns to its default position.
Paper is Jammed
The most common problem with dot matrix printers is the jamming of paper. This problem is mostly caused because a piece of paper gets stuck in the printer. The paper can get stuck under the roller of the printer due to the printing motion. This prevents other papers from passing through. This problem can also occur while printing labels. The labels may get separated from their covers and get stuck to the printer roller.
1. Try to dislodge the paper with a small object like a paper clip.
2. If the above step does not work, remove the roller of the printer. Then remove the paper.
Prints nonsensical characters
If the printer is not configured properly or the printer driver is inappropriate, the printer will not print properly.
1. Check the DIP switch of the printer. The DIP switch controls actions like carriage return and line feed. Set these properties properly.
2. Check the printer driver to see if it is the proper one for the printer.
3. A loose or faulty printer cable can cause improper printing. Try printing a document after replacing the cable with an IEEE 1284 compliant cable.
4. Try the printer self-test. If the printer fails the self-test, it may be faulty.
The Printer Displays Flashing Lights
Flashing lights can indicate one of many problems. The printer uses this signal to indicate some internal problem. It could be a paper jam or a damaged system board. There are different patterns for flashing lights. Each pattern indicates a different problem. Refer to the printer manual to find out the cause of the flashing lights.
Printer Shuts Down and Restarts Repeatedly
The printer can sometimes stop working and then recover on its own. This problem can be caused due to overheating.
1. Check the thermistor of the printer. The thermistor keeps the printer from overheating.
2. Replace the thermistor if it is faulty.
18.6.4 Troubleshooting Inkjet Printers
Inkjet printers are generally hassle-free and easy to maintain. The general problems that can occur with inkjet printers are blank printouts, white streaks on a printout and messy printouts.
The Printouts from the Printer are Blank
An inkjet printer can sometimes look like it is working fine, but the printouts turn out to be blank. This problem is most probably a result of faulty ink cartridges.
1. Check if the plastic cover has been removed from the ink cartridge.
2. There may be air entrapment inside the cartridge. To undo any such fault, cover the cartridge in a tissue and shake it gently.
3. Try printing with another ink cartridge. This will help to verify a fault in the cartridge and also to find out if the cartridge is empty.
The Color Printouts are Faulty
If an inkjet printer is not properly printing color printouts, it is also mostly a result of a faulty ink cartridge.
1. Wear gloves to prevent ink from falling on your hands.
2. Clean the cartridge with a soft wet tissue.
3. Dry the cartridge.
4. Try printing. If the printout is still improper, one of the colors must have run out in the ink cartridge.
The ink cartridge is leaking
Leaky cartridges can cause a great deal of problems in printing. It also leads to unnecessary wastage of ink. In this case, lay the ink cartridge on a wet tissue. The print head should touch the tissue so that the excess ink can be absorbed.
Printer does not recognize the cartridge
Printing is not possible if the printer does not recognize the ink cartridge.
1. Verify whether the cover of the cartridge has been removed.
2. Wipe the ink cartridge carefully with a wet tissue and let it dry.
3. Clean the print circuitry thoroughly.
4. Turn the printer off.
5. Remove all connections from the printer like the power cord and cables. Wait for some time.
6. Reconnect all cables and the power cord to the printer.
7. Turn the printer on.
8. Print a test page.
Horizontal White Lines in a Printout
The most common cause of white lines and unclear printouts is dirt in the printer. To clean the printer:
1. Turn off the printer.
2. Check the manual for cleaning instructions. If the instructions are provided, follow them.
3. If the manual does not have cleaning instructions, clean the printer contacts with a moist soft cloth.
4. To clean the print head or cartridges, use the cleaning button on the printer if it is there.
5. If there are no cleaning buttons, soak the print head in warm water for some time.
6. Dry the print head.
7. Reinstall the ink cartridge.
8. Print a test page.
_ Do not let water near the ventilation dents of the printer. Avoid ammonia-based cleaning liquids. It is best to clean the printer with plain water.
18.6.5 Troubleshooting Laser Printers
Laser printers offer very high quality outputs. But because of their complicated design, it is somewhat tedious to troubleshoot laser printers.
Output from the Laser Printer is not clear
The printouts from laser printers are usually of high precision and quality. If the printout is not clear, the problem may be because of dirt or inadequate toner. Horizontal lines throughout the printouts indicate dirty drums or rollers in the printer.
To clean the printer :
1. Turn off the printer and remove any connections.
2. Wipe the exterior of the printer according to instructions in the printer manual.
3. If no instructions are provided in the manual, clean the exterior with a soft damp cloth.
4. Be very careful not to let water inside the printer.
5. Open the printer and remove the paper trays.
6. Remove the ink powder toner.
7. Clean the cavity where toner is places, with a clean dry cloth. Some laser printers are supplied with a brush. Use the brush if it is provided.
8. Clean the mirror of the printer with the brush. Do not use cloth to wipe the mirror.
9. Clean spilled toner ink in the interior of the printer.
10. Clean the rollers of the printer, except the sponge roller.
11. Replace the toner cartridge if the above steps do not work.
Images are Disproportionate
The drive motor of the laser printer must move the paper at an even speed. This ensures even printing on paper. If the images printed by the laser printer are too long or too short, then it is a result of a faulty drive motor. In this case, contact the printer manufacturer.
Printouts are Black All Over
If the corona wire is damaged, it can lead to the printing of completely black pages.
1. Check the corona wire of the printer.
2. If it is not damaged or faulty, replace the toner cartridge of the printer.
Printouts Contain White Patches
If the toner cartridge is not supplying ink properly to the paper, the printouts will have uneven white areas in them. Remove the toner cartridge and shake it. Then replace the toner cartridge.
Printouts Show Identical Marks Repeatedly
A defective fuser assembly can cause repetitive marks like smudges on printouts.
1. Clean the fuser assembly according to the printer manual.
2. If the printouts are still defective, the fuser assembly will have to be replaced.
The printer is a device that prints text documents and images on paper. It is a peripheral output device. It prints the data that is processed by the computer. Printers are broadly classified in two groups - impact printers and non-impact printers. We can also classify printers on the basis of features like usage of color and fonts. 18.1 Impact Printers Impact printers are used for printing documents as well as graphics. The working of impact printers is very similar to typewriters. A print head is brought in contact with an ink ribbon. The impact results in printing on paper under the ink ribbon. The dot matrix printer is an example of impact printer. 18.1.1 Dot Matrix Printer Dot matrix printer uses a matrix of metal pins on the print head to create dots. An ink-soaked ribbon is placed between the paper and the print head. The print head is banged against the ribbon with considerable force. The impact causes imprint of text on the paper. As a result, dot matrix printers are noisy. Dot matrix printers do not produce high quality documents or graphics. Low-quality applications use dot matrix printers. This type of printer is useful in creation of multi-part documents like invoices and receipts. Dot matrix printers are used in carbon copy printing. The number of metal pins in the print head determines the quality of output of a dot matrix printer. The number of metal pins in the dot matrix printers varies from 9 to 24. The best quality dot matrix printers have 24 metal pins. The print head of the dot matrix printer runs repeatedly across the surface of the page being printed. The difference between typewriters and dot-matrix printers is that the typewriter uses a fixed number of alphabetical keys. The dot matrix printers use the matrix of dots to create individual letters or images. The metal pins on the print head of the printer are driven by electromagnets. Dot matrix printers can achieve high resolutions by moving the print head slowly. These printers can be monochrome or color printers. The color printers use a multi-colored striped ink ribbon to print. Dot-matrix printers have a speed of 30 to 550 cps. 18.2 Non-impact Printers Non-impact Printers are characterized by quiet operation. Non-impact printers do not function by mechanical striking of the print head on the paper. Inkjet and laser printers are types of non-impact printers. 18.2.1 Inkjet Printers An Inkjet Printer places extremely minute amounts of electrically charged ink on paper to create images or text. The drops of ink are sprayed through a series of nozzles and are around 60 microns in diameter, and are positioned with very high precision. Inkjet printers use color as well as monochrome cartridges. This type of printer provides high quality printing at an affordable price. The power supply of the printer provides the electricity to function. It is usually a part of the printer itself. A circuit board controls the operation of the printer. The circuit board contains the microprocessor and the memory. The interface ports connect the printer to the computer. Most computers connect to the printer through the parallel port. Some printers nowadays use the serial port, USB (Universal Serial Bus) port or Small Computer System Interface (SCSI) port for connecting to the computer. - Inkjet Printer The bubble jet printer is a type of inkjet printer. In this type of printer, many resistors are used. These resistors create heat. The heat causes vaporizing of ink. The vaporizing process leads to creation of a bubble in the ink. The creation of the bubble leads to expansion of the ink inside the cartridge and a drop of ink is ejected. This drop of ink is expelled from the print head. The print head has nozzles from which the ink is ejected. 18.2.2 Laser Printer The laser printer uses a beam of laser for the purpose of printing. The basis of the functioning of the laser printer is the principle of static electricity. Electric charge that accumulates on an insulated object is called static electricity. Objects that have oppositely charged fields of static electricity are attracted to each other. This happens in the same manner as oppositely charged atoms are attracted to each other. The laser printer uses this property to combine ink powder and paper. The laser printer consists of a revolving cylinder that is made up of photoconductive material. The drum is charged with the help of a charging wire called the charge corona wire. This wire has electric current passing through it. The laser printer works in the following manner :1. The photoconductive drum is given a positive or negative charge by the charge corona wire.
2. When the drum starts to revolve, a laser beam is shone on it. This laser beam consists of light photons. The laser assembly shines the laser beam on a mirror. The beam is then reflected off the mirror. As a result, the drum that is made up of photoconductive material is discharged.
3. The areas of the drum that are touched by the laser develop the opposite charge of the drum.
4. The laser etches figures and characters on the surface of the photoconductive drum. The figures or characters are actually a pattern of electric charges
5. In this case, let us assume that the drum is positively charged. Therefore, the laser-etched areas will be negatively charged.
6. Thereafter, a fine ink powder called toner is sprinkled on the paper. This powder has to be positively charged.
7. As the drum rolls, the toner adheres to the laser-etched area of the drum. It is repelled from the positively charged area of the drum. Thus, the laser pattern is etched on the drum with toner.
8. After this, the drum rolls over a paper. The paper passes along a belt under the drum.
9. The paper is given a negative charge. This negative charge must be stronger than the charge of the laser-etched electric image. This will help the toner to leave the negative area on the drum for the negatively charged paper.
10. The paper is discharged as it moves out. This will prevent the paper from getting attached to the positively charged drum. The paper moves at the same speed as the drum. Otherwise, the image will not be reproduced exactly.
11. The paper is passed through a fuser. This is a pair of heated rollers in the laser printer. As the paper passes through the fuser, the toner melts due to the heat. The toner is thus fixed on the paper.
12. The fuser rolls out the paper to the output tray. The printing process is thus complete.
Working of a Laser Printer Printouts from laser printers are warm because they pass through the fuser before coming out. However, the paper moves at a very high speed and therefore, it does not get burned. The fuser rollers must be coated with Teflon, which is a non-stick material. This material prevents the collection of toner on the fuser. 18.3 Attributes of a Printer Characteristics like speed and quality of output differentiate the different printers that we use. Attributes of a printer vary from type to type. We can classify printers on the basis of the following characteristics :_ Speed -efines the speed at which a printer prints documents. The speed of a printer is measured in characters per second (cps) or pages per minute (ppm). Printer speeds vary widely from type to type. Laser printers can print up to 20 ppm.
_ Dots Per Inch - Specifies the number of pixels or dots of ink that the printer uses while printing an image or document. Dots Per Inch (dpi) is a print setting that the printer uses while transferring an image or document from the computer to paper. A 300 dpi printer will use 300 dots of ink across an inch, vertically as well as horizontally. As a result, a square inch will have 90,000 pixels or dots of ink. The dpi provides a measure of the quality of a printed document or image. A higher dpi measurement indicates a higher quality printer.
18.4 Structure of a Printer The printer consists of various parts that accept, support, and move the paper during the process of printing. All these parts have to work in co-ordination so that the printer works properly. The different parts of a printer are :_ Feeder - Accepts the paper and forwards individual sheets as printing progresses.
_ Support - Provides a support for the paper that is loaded in the feeder.
_ Edge Guides - Provides proper adjustment according to the width of the paper. There are two such edge guides. The left guide can be shifted according to the width required.
_ Cover - Covers the printing process. The cover is opened only while replacing ink cartridges.
_ Output Tray - Accepts the paper that comes out.
_ Output Tray Extension - Holds the paper that comes out of the printer.
7.1.1 Advanced Technology Attachment We can examine the internal parts of the printer if we remove the cover. The parts of the printer that are covered are:_ Cartridge -ontains the ink for printing.
_ Print Head - Delivers the ink to the page that is being printed.
_ Cover of Cartridge - Provides a cover for the ink cartridge. This cover is removed only when a cartridge has to be replaced.
_ Adjustable Lever - Provides adjustment for distance between print head and paper. This adjustment is essential for avoiding smearing of ink on the paper.
_ Control Panel - Provides control for various actions of the printer. The control panel consist of the following buttons:
_ Power - Turns the printer ON or OFF. If this button is pressed twice when the printer is ON, the printer memory is erased.
_ Paper - ccepts or ejects paper. This button is pressed to resume printing after an error in the process.
_ Ink Level - akes the print head check the ink level. This happens when insufficient ink is detected in the cartridge. If the cartridge is empty, the ink level button makes the print head go to cartridge replacement mode. After the cartridge is replaced, the print head resumes its default mode.
_ Roll Paper - Used for roll paper. This button prints a guideline for cutting the roll paper.
Support
Edge Guides
Output Tray
Cover
Feeder
Output Tray
Extension
Internal Parts of a Printer The back of the printer has three ports. One port is for connection of the power cord. Another port is for connection of the printer to the USB port of the computer. The third port is to connect the parallel port of the computer to the printer. Most printers connect to the parallel port or USB port of the computer. A few printers also connect to the computer via the serial port. 18.5 Installing a Printer The printer must be properly connected to the computer. The printer software must be installed correctly. The printer is first connected to the computer through the cables. Then the printer driver is installed. 18.5.1 Connecting the Printer The printer must be connected properly to the appropriate port on the computer. You must use a good quality cable for the connection Best practice 1. Study the printer manual thoroughly.2. Keep some space free around the printer for the purpose of ventilation.
3. Use the IEEE 1284 bi-directional printer cable for connecting printer to the computer.
4. Check the printer manual to ensure that all parts are provided. Some printers are provided with cables.
5. Check the printer for any missing or damaged parts immediately after unpacking.
Precautions 1. Wear an antistatic wristband.2. Do not connect the printer to the power supply during the process of connecting.
Control Panel
Adjustment
Lever
Cartridge
Cover
Print Head
Hands on exercise To connect a printer :1. Find an appropriate, flat place to keep the printer.
2. Take the IEEE 1284 parallel printer cable and study both ends. One of the ends will have 25 pins. Connect this end to the parallel port of the computer.
3. Secure the two hand screws on the cable plug.
4. Connect the other end of the cable to the printer's parallel port socket. If the printer has retaining clips at the parallel port socket, latch the clips securely.
5. Connect the power cord to the printer's power socket.
6. Turn the printer ON.
7. Install the cartridges in the printer according to the directions in the printer manual.
_ Not all printers connect to the parallel port. Some printers also connect to he USB port of the computer. Verify which port connects to the printer before starting the procedure.
18.5.2 Installing the Printer Drivers The printer driver is the software that controls the operation of the printer. It converts data from the computer to a format that is understood by the printer. The printer driver passes data that is to be printed, to the printer. The printer driver has to be installed for the printer to work. The printer driver can also be replaced if there are later versions of the driver available. We can download printer drivers from the printer manufacturers' site. To install the printer driver after connecting the printer, first turn on the computer. Insert the CD or floppy that comes with the printer. Follow the instructions of the printer manufacturer. This will install the driver automatically. 18.5.3 Configuring the Printer It is possible to set certain default properties for the printer by configuring it. By configuring a printer, we can avoid the setting of properties for the printer repeatedly. Hands on exercise To configure a printer:1. Select Start _ Settings _ Printers.
2. Right-click the Printer that has to be configured.
3. Select Properties. The Printer Properties dialog box is displayed.
Printer Properties Dialog Box 4. Use the different tabs and options in this screen to configure properties of the printer as required. 18.6 Troubleshooting There are many problems that can arise during the working of the printer. We have to troubleshoot the printer in order to make it work properly. Best Practices 1. Read the printer manual thoroughly.2. Study the safety instructions in the manual.
3. Try printing after connecting the printer to another computer.
4. Try printing a document after replacing the ink cartridge. If the printing is faulty even after replacing the cartridge, it is almost certain that the printer is at fault.
Precautions 1. Wear an antistatic wristband.2. Disconnect the printer from the power supply.
18.6.1 General Troubleshooting The printer can stop functioning because of a number of reasons. The computer may not be recognizing the printer or the printer settings may be incorrect.1. If the printer is displaying flashing lights, refer to the printer manual. The problem that is causing the flashing lights will be explained in the manual.
2. Check if the printer is getting power supply by checking the power display on the printer.
3. Check whether paper that is loaded in the printer is properly placed and is not jammed. Adjust the edge guides of the printer if necessary.
4. Find out if the cartridge in the printer is new or used. If the cartridge is new, ensure that the protective plastic layer on the cartridge has been removed.
5. Check the cable connections of the printer.
6. Run the printer self-test. The printer self-test varies from model to model. Refer the instructional manual of the printer to run the self-test. If the printer fails the self-test, the printer has a problem.
7. Check if the print head is moving. A stationary print head could be the result of a failed transport motor.
8. If the printer passes the self-test, print a test page. If the test page does not print properly, the problem is due to an improper connection between the computer and printer.
9. If the test page prints properly, the problem may be caused due to improper configuration. The output may be directed to the wrong port.
10. Connect the printer to another computer to see if it works.
11. If there are any other parallel devices connected to the computer, turn off those devices to find out if they are causing the problem.
12. Restart the printer and try to operate it. This step can help repair mistakes in internal settings of the printer.
13. Go to the CMOS settings of the computer and verify that the parallel port is installed and working properly.
14. In the BIOS settings of the computer, check the parallel mode. Ensure that the printer is not set to ECP mode. This is because the ECP mode is not suitable to the working of many printers.
15. In the BIOS settings, check the parallel port IRQ. It is preferable to set the IRQ to 7. The sound card of the computer generally uses the IRQ 5. As a result, there can be a conflict between the printer and sound card.
16. Printers that require bi-directional communication need to have the parallel port enabled accordingly. We can do this by setting the parallel port mode to EPP (Enhanced Parallel Port) in the BIOS settings.
17. Check the DIP switches. The DIP switch is a group of switches that sets the configuration for the computer. It is used in place of the jumpers. By checking the DIP switch settings, we can ensure that the configuration of the printer is not faulty.
18.6.2 Printer Driver does not Function Properly The printer driver can cause many printing problems. These problems are very difficult to detect and trace to the printer driver. This is because the printer driver is very complex software. A problematic printer driver can cause some fonts or formats to cause errors while printing, while others work fine. Some of the possible symptoms of a problem with the printer driver are :_ Appearance of black boxes all over the printout.
_ Formation of nonsensical characters in the printout.
_ The application crashes as the printing progresses.
_ Missing characters or lines in a printout.
1. Update the printer driver. For this, contact the printer manufacturer or download the driver from their site.
2. If an updated driver is not available, try to find a printer driver that is compatible with the printer.
3. Install the new printer driver.
18.6.3 Troubleshooting Dot Matrix Printers Dot matrix printers are not widely used presently. However, they are essential in applications that require carbon-copy printing. These printers are not very complicated and are easy to troubleshoot. Appearance of White Lines in Printouts A very common problem with dot matrix printers is the formation of white lines in printouts. These lines are mostly horizontal and occur between lines of text or images. This problem by and large occurs due to a problem in the print head.1. Check the print head to see if all the pins are working properly.
2. Check the print head ribbon. It must be tightly wound to the print head.
3. Ensure that the print ribbon is in good condition.
4. Collection of residue on the print head can lead to printing problems. Clean the print head with alcohol.
5. If none of the above steps helps, replace the print head.
The Carriage of the Printer is Moving, but Pages are Blank If the carriage of the printer is moving and the printing is not taking place, it is mostly caused by the print head or the ink ribbon.1. Check the ink ribbon to see if it is dry.
2. If the ink ribbon is fine, check if the print head is striking the ribbon.
3. Check if the printer ribbon is being advanced every time the print head returns to its default position.
Paper is Jammed The most common problem with dot matrix printers is the jamming of paper. This problem is mostly caused because a piece of paper gets stuck in the printer. The paper can get stuck under the roller of the printer due to the printing motion. This prevents other papers from passing through. This problem can also occur while printing labels. The labels may get separated from their covers and get stuck to the printer roller.1. Try to dislodge the paper with a small object like a paper clip.
2. If the above step does not work, remove the roller of the printer. Then remove the paper.
Prints nonsensical characters If the printer is not configured properly or the printer driver is inappropriate, the printer will not print properly.1. Check the DIP switch of the printer. The DIP switch controls actions like carriage return and line feed. Set these properties properly.
2. Check the printer driver to see if it is the proper one for the printer.
3. A loose or faulty printer cable can cause improper printing. Try printing a document after replacing the cable with an IEEE 1284 compliant cable.
4. Try the printer self-test. If the printer fails the self-test, it may be faulty.
The Printer Displays Flashing Lights Flashing lights can indicate one of many problems. The printer uses this signal to indicate some internal problem. It could be a paper jam or a damaged system board. There are different patterns for flashing lights. Each pattern indicates a different problem. Refer to the printer manual to find out the cause of the flashing lights. Printer Shuts Down and Restarts Repeatedly The printer can sometimes stop working and then recover on its own. This problem can be caused due to overheating.1. Check the thermistor of the printer. The thermistor keeps the printer from overheating.
2. Replace the thermistor if it is faulty.
18.6.4 Troubleshooting Inkjet Printers Inkjet printers are generally hassle-free and easy to maintain. The general problems that can occur with inkjet printers are blank printouts, white streaks on a printout and messy printouts. The Printouts from the Printer are Blank An inkjet printer can sometimes look like it is working fine, but the printouts turn out to be blank. This problem is most probably a result of faulty ink cartridges.1. Check if the plastic cover has been removed from the ink cartridge.
2. There may be air entrapment inside the cartridge. To undo any such fault, cover the cartridge in a tissue and shake it gently.
3. Try printing with another ink cartridge. This will help to verify a fault in the cartridge and also to find out if the cartridge is empty.
The Color Printouts are Faulty If an inkjet printer is not properly printing color printouts, it is also mostly a result of a faulty ink cartridge.1. Wear gloves to prevent ink from falling on your hands.
2. Clean the cartridge with a soft wet tissue.
3. Dry the cartridge.
4. Try printing. If the printout is still improper, one of the colors must have run out in the ink cartridge.
The ink cartridge is leaking Leaky cartridges can cause a great deal of problems in printing. It also leads to unnecessary wastage of ink. In this case, lay the ink cartridge on a wet tissue. The print head should touch the tissue so that the excess ink can be absorbed. Printer does not recognize the cartridge Printing is not possible if the printer does not recognize the ink cartridge.1. Verify whether the cover of the cartridge has been removed.
2. Wipe the ink cartridge carefully with a wet tissue and let it dry.
3. Clean the print circuitry thoroughly.
4. Turn the printer off.
5. Remove all connections from the printer like the power cord and cables. Wait for some time.
6. Reconnect all cables and the power cord to the printer.
7. Turn the printer on.
8. Print a test page.
Horizontal White Lines in a Printout The most common cause of white lines and unclear printouts is dirt in the printer. To clean the printer:1. Turn off the printer.
2. Check the manual for cleaning instructions. If the instructions are provided, follow them.
3. If the manual does not have cleaning instructions, clean the printer contacts with a moist soft cloth.
4. To clean the print head or cartridges, use the cleaning button on the printer if it is there.
5. If there are no cleaning buttons, soak the print head in warm water for some time.
6. Dry the print head.
7. Reinstall the ink cartridge.
8. Print a test page.
_ Do not let water near the ventilation dents of the printer. Avoid ammonia-based cleaning liquids. It is best to clean the printer with plain water.
18.6.5 Troubleshooting Laser Printers Laser printers offer very high quality outputs. But because of their complicated design, it is somewhat tedious to troubleshoot laser printers. Output from the Laser Printer is not clear The printouts from laser printers are usually of high precision and quality. If the printout is not clear, the problem may be because of dirt or inadequate toner. Horizontal lines throughout the printouts indicate dirty drums or rollers in the printer.To clean the printer :
1. Turn off the printer and remove any connections.
2. Wipe the exterior of the printer according to instructions in the printer manual.
3. If no instructions are provided in the manual, clean the exterior with a soft damp cloth.
4. Be very careful not to let water inside the printer.
5. Open the printer and remove the paper trays.
6. Remove the ink powder toner.
7. Clean the cavity where toner is places, with a clean dry cloth. Some laser printers are supplied with a brush. Use the brush if it is provided.
8. Clean the mirror of the printer with the brush. Do not use cloth to wipe the mirror.
9. Clean spilled toner ink in the interior of the printer.
10. Clean the rollers of the printer, except the sponge roller.
11. Replace the toner cartridge if the above steps do not work.
Images are Disproportionate The drive motor of the laser printer must move the paper at an even speed. This ensures even printing on paper. If the images printed by the laser printer are too long or too short, then it is a result of a faulty drive motor. In this case, contact the printer manufacturer. Printouts are Black All Over If the corona wire is damaged, it can lead to the printing of completely black pages.1. Check the corona wire of the printer.
2. If it is not damaged or faulty, replace the toner cartridge of the printer.
Printouts Contain White Patches If the toner cartridge is not supplying ink properly to the paper, the printouts will have uneven white areas in them. Remove the toner cartridge and shake it. Then replace the toner cartridge. Printouts Show Identical Marks Repeatedly A defective fuser assembly can cause repetitive marks like smudges on printouts.1. Clean the fuser assembly according to the printer manual.
2. If the printouts are still defective, the fuser assembly will have to be replaced.
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