Ch-10 Printers

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Ch-10 Printers
2014-05-07 13:51:49
Printers Assembly Configuring
Chapter 10 A+ Study Guide
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  1. __ use a paper feed mechanism called a tractor feed that requires special paper. It’s continuous feed paper with holes running down both edges. In a manner of speaking, typewriters are like __. Both use an inked ribbon and an __ head to make letters on the paper. The major difference is that the printer can accept input from a computer.
    Impact Printers
  2. This is one of the oldest printing technologies in use. These impact printers contain a wheel with raised letters and symbols on each “petal” When the printer needs to print a character, it sends a signal to the mechanism that contains the wheel. This mechanism is called the print head. The print head rotates the daisy wheel until the required character is in place. An electromechanical hammer (called a solenoid) then strikes the back of the petal containing the character. The character pushes up against an inked ribbon that ultimately strikes the paper, making the impression of the requested character. __ are impact printers, you can print on multipart forms. It is relatively inexpensive compared to the price of a laser printer of the same vintage. Finally, the print quality is comparable to that of a typewriter because it uses a very similar technology.
    Daisy-Wheel Printers
  3. These printers work in a manner similar to daisy-wheel printers, but instead of a spinning, character-imprinted wheel, the print head contains a row of pins. These pins are triggered in patterns that form letters and numbers as the print head moves across the paper. The main disadvantage of __ printers is their image quality, which can be quite poor compared to the quality produced with a daisy wheel. __ technology ultimately improved to the point that a letter printed on a __ printer was almost indistinguishable from typewriter output. This level of quality is known as near letter quality. Some __ (like the Epson DFX series) can print at close to a page per second. __ printers can print multipart forms. __ printers quickly made daisy-wheel printers obsolete. Most impact printers have an option to adjust how close the print head rests from the ribbon. So if your printing is too light, you may be able to adjust the print head closer to the ribbon. If it’s too dark or you get smeared printing, you may be able to move the print head back.
    Dot-Matrix Printers
  4. One of the most popular types of printers in use today are __ printers. As opposed to impact printers, which strike the page, these printers spray ink on the page to form the image. Older __ printers used a reservoir of ink, a pump, and a nozzle to accomplish this. __ printers work much more efficiently and are much cheaper. The main difference is that in a __ printer, droplets of ink are sprayed onto a page and form patterns that resemble the items being printed. You can think of it as spraying droplets of ink in a very high-definition dot-matrix pattern.
    Inkjet (Bubble-Jet)
  5. Print head/ink cartridge, Head carriage, belt, and stepper motor, Paper-feed mechanism, Control, interface, and power circuitry are __.
    Parts of a Typical Bubble-Jet Printer
  6. The first part of a bubble-jet printer is the one people see the most:__. This part of a printer contains many small nozzles (usually 100 to 200) that spray the ink in small droplets onto the page. Many times the __ is part of the ink cartridge, which contains a reservoir of ink and the print head in a removable package. Most color bubble-jet printers include multiple print heads, one for each of the CMYK print inks. Inside the ink cartridge are several small chambers. At the top of each chamber are a metal plate and a tube leading to the ink supply. At the bottom of each chamber is a small pinhole. These pinholes are used to spray ink on the page to form characters and images as patterns of dots, similar to the way a dot-matrix printer works but with much higher resolution. When the printer is done printing, the __ moves back to its maintenance station.
    The Print Head
  7. __contains a small suction pump and ink-absorbing pad. To keep the ink flowing freely, before each print cycle the maintenance station pulls ink through the ink nozzles using vacuum suction. This expelled ink is absorbed by the pad. The __ serves two functions: to provide a place for the print head to rest when the printer isn’t printing and to keep the print head in working order.
    The maintenance station
  8. The print __ is the component of a bubble-jet printer that moves back and forth during printing. It contains the physical as well as electronic connections for the print head and (in some cases) the ink reservoir. Note the clips that keep the ink cartridge in place and the electronic connections for the ink cartridge. These connections cause the nozzles to fire, and if they aren’t kept clean, you may have printing problems.
    Head Carriage
  9. The __ and __ make the print head carriage move. A __ is a precisely made electric motor that can move in the same very small increments each time it is activated. That way, it can move to the same position(s) time after time. The motor that makes the print head carriage move is also often called the carriage motor or carriage __. In addition to the motor, a __ is placed around two small wheels or pulleys and attached to the print head carriage. This is called the carriage __, is driven by the carriage motor and moves the print head back and forth across the page while it prints. To keep the print head carriage aligned and stable while it traverses the page, the carriage rests on a small metal stabilizer bar.
    Belt and Stepper Motor
  10. The __ picks up paper from the paper drawer and feeds it into the printer. This component consists of several smaller assemblies. First are the pickup rollers, which are several rubber rollers with a slightly flat spot; they rub against the paper as they rotate, and feed the paper into the printer. They work against small cork or rubber patches known as separator pads, which help keep the rest of the paper in place so that only one sheet goes into the printer. The pickup rollers are turned on a shaft by the pickup stepper motor.
    Paper-Feed Mechanism
  11. The printer __ circuits are usually on a small circuit board that contains all the circuitry to run the stepper motors the way the printer needs them to work (back and forth, load paper and then stop, and so on). These circuits are also responsible for monitoring the health of the printer and reporting that information back to the PC.
  12. The second power component, the circuitry (commonly called a port), makes the physical connection to whatever signal is coming from the computer (parallel, serial, network, infrared, and so on) and also connects the physical __ to the control circuitry. The __ circuitry converts the signals from the __ into the datastream that the printer uses.
  13. These conductive pathways convert 110V (in the United States) or 220V (in most of the rest of the world) from a standard wall outlet into the voltages the bubble-jet printer uses, usually 12V and 5V, and distribute those voltages to the other printer circuits and devices that need it. This is accomplished through the use of a transformer. A transformer, in this case, takes the 110V AC current and changes it to 12V DC (among others). This transformer can be either internal (incorporated into the body of the printer) or external. Either design can be used in today’s bubble-jets, although the integrated design is preferred because it is simpler and doesn’t show the bulky transformer.
    Power Circuitry
  14. Most printers that use the EP process contain nine __: the toner cartridge, laser scanner, high-voltage power supply, DC power supply, paper transport assembly (including paper-pickup rollers and paper-registration rollers), transfer corona, fusing assembly, printer controller circuitry, and ozone filter.
    Basic Components
  15. Toner is a black carbon substance mixed with polyester resins to make it flow better and iron oxide particles to make it sensitive to electrical charges. These two components make the toner capable of being attracted to the photosensitive drum and of melting into the paper. In addition to these components, toner contains a medium called the developer (also called the carrier), which carries the toner until it is used by the EP process. The __ also contains the EP print drum. This drum is coated with a photosensitive material that can hold a static charge when not exposed to light but cannot hold a charge when it is exposed to light—a curious phenomenon and one that EP printers exploit for the purpose of making images.
    Toner Cartridge
  16. The EP process requires __ electricity. The __ provides the high voltages used during the EP process. This component converts AC current from a standard wall outlet (120V and 60Hz) into higher voltages that the printer can use. This high voltage is used to energize both the charging corona and the transfer corona. Anything with the words high voltage in it should make you pause before opening a device and getting your hands into it. The __ can hurt or kill you if you’re inside a laser printer and don’t know what you’re doing.
    High-Voltage Power Supply (HVPS)
  17. The high voltages used in the EP process can’t power the other components in the printer (the logic circuitry and motors). These components require low voltages, between +5 VDC and +24VDC. The __ converts house current into three voltages: +5VDC and –5VDC for the logic circuitry and +24VDC for the paper-transport motors. This component also runs the fan that cools the internal components of the printer.
    DC Power Supply (DCPS)
  18. The __ is responsible for moving the paper through the printer. It consists of a motor and several rubberized rollers that each performs a different function. The first type of roller found in most laser printers is the feed roller, or paper-pickup roller. This D-shaped roller, when activated, rotates against the paper and pushes one sheet into the printer. This roller works in conjunction with a special rubber separator pad to prevent more than one sheet from being fed into the printer at a time. Another type of roller that is used in the printer is the registration roller. There are actually two registration rollers, which work together. These rollers synchronize the paper movement with the image-formation process in the EP cartridge. The rollers don’t feed the paper past the EP cartridge until the cartridge is ready for it. Both of these rollers are operated with a special electric motor known as an electronic stepper motor. This type of motor can accurately move in very small increments. It powers all the paper-transport rollers as well as the fuser rollers. When the laser writes the images on the photosensitive drum, the toner then sticks to the exposed areas; we’ll cover this in the next section, “Electrophotographic (EP) Print Process.”
    Paper-Transport Assembly
  19. The __ assembly is given a high-voltage charge, which is transferred to the paper, which in turn pulls the toner from the photosensitive drum. Included in the transfer corona assembly is a static-charge eliminator strip that drains away the charge imparted to the paper by the corona. If you didn’t drain away the charge, the paper would stick to the EP cartridge and jam the printer. There are two types of __ assemblies: those that contain a __ wire and those that contain a __ roller. The __ wire is a small-diameter wire that is charged by the HVPS. The wire is located in a special notch in the floor of the laser printer (under the EP print cartridge). The __ roller performs the same function as the __ wire, but it’s a roller rather than a wire. Because the __ roller is directly in contact with the paper, it supports higher speeds.
    Transfer Corona
  20. EP laser printers incorporate a device known as a __, which uses two rollers that apply pressure and heat to __ the plastic toner particles to the paper. The __ is made up of three main parts: a halogen heating lamp, a Teflon-coated aluminum fusing roller, and a rubberized pressure roller. The __ uses the halogen lamp to heat the __ roller to between 329 F (165 C) and 392 F (200 C). As the paper passes between the two rollers, the pressure roller pushes the paper against the __ roller, which melts the toner into the paper.
    Fusing Assembly
  21. This large circuit board converts signals from the computer into signals for the various assemblies in the laser printer, using a process known as rasterizing. This circuit board is usually mounted under the printer. The board has connectors for each type of interface and cables to each assembly. When a computer prints to a laser printer, it sends a signal through a cable to the __. The __ formats the information into a page’s worth of line-by-line commands for the laser scanner. The controller sends commands to each of the components, telling them to wake up and begin the EP print process.
    Printer Controller Circuitry
  22. Ozone is a chemically reactive gas that is created by the high-voltage coronas (charging and transfer) inside the printer. Because ozone is chemically reactive and can severely reduce the life of laser printer components, many older laser printers contain a __ to remove ozone gas from inside the printer as it is produced. This __ must be removed and cleaned with compressed air periodically. Most newer laser printers don’t have __. This is because these printers don’t use transfer corona wires but instead use transfer corona rollers, which dramatically reduce ozone emissions.
    Ozone Filter
  23. The __ print process is the process by which an __ laser printer forms images on paper. It consists of six major steps, each for a specific goal. Although many different manufacturers call these steps different things or place them in a different order, the basic process is still the same. Here are the steps in the order you will see them on the exam: 1. Cleaning 2. Charging 3. Writing (exposing) 4. Developing 5. Transferring 6. Fusing. CCWDTF.
    Electrophotographic (EP) Print Process
  24. In the first part of the laser print process, a rubber blade inside the EP cartridge scrapes any toner left on the drum into a used toner receptacle inside the EP cartridge, and a fluorescent lamp discharges any remaining charge on the photosensitive drum (remember that the drum, being photosensitive, loses its charge when exposed to light). This step is called the __ step. The __ cartridge is constantly cleaning the drum. It may take more than one rotation of the photosensitive drum to make an image on the paper. The __ step keeps the drum fresh for each use. If you didn’t clean the drum, you would see ghosts of previous pages printed along with your image. The amount of toner removed in the cleaning process is quite small. The cartridge will run out of toner before the used toner receptacle fills up.
    Step 1: Cleaning
  25. The second step in the EP process is the __ step. In this step, a special wire or roller (called a charging corona) within the EP toner cartridge (above the photosensitive drum) gets a high voltage from the HVPS. It uses this high voltage to apply a strong, uniform negative charge (around –600VDC) to the surface of the photosensitive drum.
    Step 2: Charging
  26. In the third step, the laser is turned on and scans the drum from side to side, flashing on and off according to the bits of information the printer controller sends it as it communicates the individual bits of the image. Wherever the laser beam touches, the photosensitive drum’s charge is severely reduced from –600VDC to a slight negative charge (around –100VDC). As the drum rotates, a pattern of exposed areas is formed, representing the image to be printed. You might also hear this step called the exposing step because it’s when the drum is exposed to the laser. At this point, the controller sends a signal to the pickup roller to feed a piece of paper into the printer, where it stops at the registration rollers.
    Step 3: Writing
  27. Now that the surface of the drum holds an electrical representation of the image being printed, its discrete electrical charges need to be converted into something that can be transferred to a piece of paper. The EP process step that accomplishes this is the __ step. In this step, toner is transferred to the areas that were exposed in the writing step. A metallic roller called the developing roller inside an EP cartridge acquires a –600VDC charge (called a bias voltage) from the HVPS. The toner sticks to this roller because there is a magnet located inside the roller and because of the electrostatic charges between the toner and the developing roller. While the developing roller rotates toward the photosensitive drum, the toner acquires the charge of the roller (–600VDC). When the toner comes between the developing roller and the photosensitive drum, the toner is attracted to the areas that have been exposed by the laser (because these areas have a lesser charge, –100VDC). The toner also is repelled from the unexposed areas (because they are at the same –600VDC charge and like charges repel). This toner transfer creates a fog of toner between the EP drum and the developing roller. The photosensitive drum now has toner stuck to it where the laser has written. The photosensitive drum continues to rotate until the developed image is ready to be transferred to paper in the next step.
    Step 4: Developing
  28. At the fifth step in the EP process, the developed image is rotating into position. The controller notifies the registration rollers that the paper should be fed through. The registration rollers move the paper underneath the photosensitive drum, and the process of transferring the image can begin; this is the transferring step. The controller sends a signal to the charging corona wire or roller (depending on which one the printer has) and tells it to turn on. The corona wire/roller then acquires a strong positive charge (+600VDC) and applies that charge to the paper. The paper, thus charged, pulls the toner from the photosensitive drum at the line of contact between the roller and the paper because the paper and toner have opposite charges. Once the registration rollers move the paper past the corona wire, the static-eliminator strip removes all charge from that line of the paper. If the strip didn’t bleed this charge away, the paper would attract itself to the toner cartridge and cause a paper jam. The toner is now held in place by weak electrostatic charges and gravity. It will not stay there, however, unless it is made permanent, which is the reason for the fusing step.
    Step 5: Transferring
  29. In the final step, the __ step , the toner image is made permanent. The registration rollers push the paper toward the __ rollers. Once the __ grabs the paper, the registration rollers push for only a short time more. The __ is now in control of moving the paper. As the paper passes through the __, the __ roller melts the polyester resin of the toner, and the rubberized pressure roller presses it permanently into the paper. The paper continues through the and eventually exits the printer. Once the paper completely exits the __, it trips a sensor that tells the printer to finish the EP process with the cleaning step. At this point, the printer can print another page, and the EP process can begin again.
    Step 6: Fusing
  30. For the most part, these printers operate like other printers in many ways: They all have a paper-feed mechanism (sheet-fed or roll); they all require consumables such as ink or toner and paper; they all use the same interfaces, for the most part, as other types of printers; and they are usually about the same size. __ printing technology is used in many Point of Sale terminals and older fax machines. They print on a special, waxy paper that comes on a roll; the paper turns black when heat passes over it. Thermal printers work by using a print head the width of the paper. When it needs to print, a heating element heats certain spots on the print head. The paper below the heated print head turns black in those spots. As the paper moves through the printer, the pattern of blackened spots forms an image on the page of what is being printed. Another type of thermal printer uses a heat-sensitive ribbon instead of heat-sensitive paper. A __ print head melts wax-based ink from the ribbon onto the paper. These are called __ transfer or __ wax-transfer printers.
    Thermal Printers
  31. A __ works just as its name implies: It describes the whole page being printed by sending commands that describe the text as well as the margins and other settings. The controller in the printer interprets these commands and turns them into laser pulses (or pin strikes).
    Page-Description Language
  32. The first page-description language was__. Developed by Adobe, it was first used in the Apple LaserWriter printer. It made printing graphics fast and simple. The __ printer driver describes the page in terms of “draw” and “position” commands. The page is divided into a very fine grid. PostScript can get the line drawn with fewer than five instructions. __ uses commands that are more or less in English. The commands are interpreted by the processor on the printer’s controller and converted into the print-control signals.
  33. __ was developed by Hewlett-Packard in 1984 and originally intended for use with inkjet printers as a competitor to PostScript. Since then, its role has been expanded to virtually every printer type, and it’s a de facto industry standard.
    Printer Command Language (PCL)
  34. __ is actually a Windows component and is not specific to printers. Instead, it’s a series of components that govern how images are presented to both monitors and printers. __ printers work by using computer processing power instead of their own. The printed image is rendered to a bitmap on the computer and then sent to the printer. This means that the printer hardware doesn’t need to be as powerful, which results in a less expensive printer. Generally speaking, the least expensive laser printers on the market are __ printers. Many newer printers can handle both PS and PCL (and __) and will automatically translate for you.
    Graphics Device Interface (GDI)