A+ Chapter 11 Test Answers
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Printers
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electromechanical output devices that are used to put information from computer onto paper
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Impact Printers
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use a form of impact and an inked ribbon to make an imprint on the paper use tractor feed mechanism special paper, continuous feed paper with holes down both edges
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Daisy Wheel Printers
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Impact Printer: oldest wheel with raised letters and symbols on a petal print head rotates the daisy wheel until character is in place solenoid (electromechanical hammer) strikes back of petal containing the character, character hits ribbon that strikes paper speed rated by characters per second (cps), very slow (2 - 4cps), very loud, one font inexpensive, easily readable (letter quality (LQ))
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Dot-Matrix Printers
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Impact printer print head has row of pins, which are triggered in patterns that form letters and numbers as print head moves across paper printer controller sends signal to print head which energizes which turns print wire into electromagnet which repels print pin forcing it againsttheink ribbon and making a dot on the paper poor image quality, draft quality near letter quality (NQL) almost as good as daisy wheel noisy, faster print speed, 72cps,
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Inkjet
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spray ink on the page, contain reservoir of ink, pump, nozzle; inexpensive to manufacture
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Inkjet Parts
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Print Head/Ink Cartridge Head Carriage, Belt, Stepper Motor Paper-feed mechanism Control, interface, power circuitry
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Inkjet Printer Head/Ink Cartridge
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many small nozzles (100 to 200) that spray ink in small droplets onto page Ink cartridge contains reservoir of ink and print head may be removable One print head for each CMYK (cyan, magenta, yellow, black)
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Inkjet Ink Cartridge Method
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Several small chambers in each ink cartridge at top are a metal plate and tube leading to ink, bottom is a small pinhole, these pinholes spray ink on page to form characters as patterns of dots two methods of spraying ink: 1) electric signal sent to heating element, energizing it, causes ink to vaporize, ink is pushed out forms a bubble, breaks into droplet; 2) piezoelectric element (small rod or mini drum head) that flexes when energized, outward flex pushed ink out maintenance station: small suction pump and ink-absorbing pad, pulls ink through nozzles using vacuum suction, pad absorbs expelled ink (place for print head to rest, keeps print head in working order)
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Inkjet: Head Carriage, Belt, Stepper Motor
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printer head carriage is the part that moves back and forth during printing physical and electronic connections (keep connections clean) Stepper motor: precisely made electric motor thatcan move in the same very small increments each time it is activated Carriage motor or carriage stepper motor makes printer head carriage move Belt: placed around two small wheels or pulley and attached to print head cartridge, moves print head back ad forth across page Carriage rests on stabilizer bar
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Inkjet: Paper-feed mechanism
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picks up paper from paper drawer and feeds into printer Pickup rollers: rubber, rub against paper as they rotate and feed paper to printer, work against separator pads which help keep rest of paper in place, pickup rollers are turned by pickup stepper motor paper feed sensors: tell when printer is out of paper, or a paper jam has occurred
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Inkjet: Control, interface, power circuitry
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control circuitry: small circuit board contains all circuitry to run stepper motors, monitors health of printer and reporting info back to PC interface circuitry controls connection to computer, connects to control circuitry, converts signal into datastream for printer to use power: conductive pathways convert 110V or 220V into 12V or 5V and distributes to other circuitry, uses a transformer
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Inkjet Printing Process
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calibrate system: process by which device is brought within functional specifications, aligning print heads Click Print Software sends data to printer driver Printer driver converts data being printed into printer format, ensures printer is ready to print Printer driver sends info to printer Printer stores received data in print buffer memory Printer activates cleaning cycle to purge print heads of dried ink Control circuitry activates paper feed, triggers sensor to stop feed and position paper Print head stepper motor uses print head belt and carriage to move the printhead across page little by little, step by step print head sprays ink in pattern Paper feed advances page a small amount, then repeats spraying Once page is finished feed stepper motor actuates and ejects page from printer to output tray Once final page is ejected print head is parked (rest position) and print process is done Duplexing (double sided printing)
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Page Printers
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print job instructions one a time rather than one line at a time
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EP
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electrophotographic print process: either scan image onto photosensitive drum or use an array of LEDs to create image on drum
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Laser printers
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printers that use EP process
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Basic components of a laser printer
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toner, laser scanner, high voltage power supply, DC power supply, paper transport assembly, transfer corona, fusing assembly, printer controller circuitry, ozone filter
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Toner Cartridge
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holds toner (black carbon substance mixed with polyester resins to make it flow better and iron oxide particles to make it sensitive to electrical charges) able to be attracted to toner drum and of melting into paper contains developer which carries toner until it is used by EP contains print drum coated with photosensitive material that can hold a static charge when not exposed to light but cannot hold a charge when it is exposed to light contains cleaning blade to scrape used toner off photosensitive drum
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Laser Scanning Assembly
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when exposed to light the drum discharges but only where it is exposed as drum rotates the laser scanning assembly scans laser across photosensitive drum writing image to it
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High Voltage Power Supply (HVPS)
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EP needs high voltage electricity, converts AC 120V or 60V into higher V, energizes the charging corona and the transfer corona
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DC Power Supply
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DCPS: powers logic circuitry and motors, +5VDC and +24VDC, converts house current into +5, -5, for logic and +24VDC for paper transport motors
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Paper Transport Assembly
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responsible for moving paper through printer motor and rubberized rollers feed roller or paper pickup: D-shaped, rotates against paper and pushed one sheet into printer, works with separator pad to prevent more than one from going in registration roller: synchronize paper movement with the image formation process in EP cartridge, use electronic stepper motor, powers paper transport and fuser rollers
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Transfer Corona Assembly
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given a high voltage charge which is transferred to the paper which in turn pulls toner from photosensitive drum static charge eliminator strip drains away charge on paper (don't drain the paper sticks to EP cartirdge) corona wire: small diameter, charged by HVPS, under EP print cartridge corona roller: directly in contact with paper, high speeds
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Fusing Assembly
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two rollers apply pressure and heat to fuse plastic toner particles to the paper halogen heat lamp, teflon coated aluminum-fusing roller and rubberized pressure roller halogen heats fusing roller between 329degrees and 392degrees, pressuer roller pushed paper to fusing roller which melts toner to paper
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Printer controller circuitry
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circuit board converts signals from comp to various assemblies in the laser printer using rasterizing formats info into a page's worth of line by line commands for laser scanner
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Ozone Filter
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ozone is a chemically reactive gas that is created by high voltage coronas, must be replaced
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Duplexing Assembly
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print on both sides
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Electrophotographic Print Process (EP)
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process by which EP laser printer forms images on paper 1) Processing 2) Charging 3) Exposing (writing) 4) Developing 5) Transferring 6) Fusing 7) Cleaning
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1) Processing
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receiving image and creating the image computer sends print job, printer creates print job, render one horizontal strip at a time to create image, each strip is a scan line or raster line Raster Image Processor (RIP) manages raster creation, creates image of the final page in memory
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2) Charging
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charging corona with EP toner gets high voltage from HVPS, applys strong -600VDC uniform negative charge to the photosensitive drum
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3) Exposing
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exposing drum to image laser turned on and scans drum from side to side, flashing on and off according ot bits of info that printer controller sends wherever laser beam touches drum's charge is reduced to -100VDC pattern of exposed area is formed representing image ot be printed controller sends signal to pickup roller to feed paper
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4) Developing
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discrete electrical charges need to be converted into something that can be transferred to a piece of paper toner is transferred to the areas that were exposed in the writing step developing roller inside EP cartridge acquires a -600VDC charge toner sticks to roller because of electrostatic charges between toner and developing roller creates fog of toner between EP drum and developing roller toner stuck to drum were laser has written
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5) Transferring
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controller notifies registration rollers that paper should be fed controller sends signal to charging corona to turn on, and it acquires a strong positive charge +600VDC and applies charge to paper paper pulls the toner from the photosensitive drum at the line of contact between the roller and the paper static eliminator strip removes charge from paper
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6) Fusing
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fuser rollers at 350degrees melt polyester resin of toner and the pressure rollers press it permanently to paper once paper is out, sensor tells printer to clean
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7) Cleaning
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rubber blade inside EP cartridge scrapes any leftover toner off drum fluorescent lamp discharges any remaining charge on photosensitive drum
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Thermal Printers
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POS systems, fax machines, waxy paper use print head that is width of paper, turns black when heat passes over it few moving parts, long life
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Virtual Printers
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sends desired output to a file instead of paper print to XPS (Open XML Paper Specification) is Microsoft's PDF
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Printer Interface Components
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collection of hardware (port) and software that allows the printer to communicate with a computer
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Serial Printers
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one bit at a time
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Parallel Printers
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receives 8 bits at a time over 8 wires, DB 25 connector to computer and 36pin Centronics connector to printer IEEE 1284 compliant
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Universal Serial Bus (USB)
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most popular interface, higher transfer rate
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Ethernet
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have internal NIC and ROM to allow communication on a network
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Wireless
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802.11 and bluetooth (10m) uses radio waves ad hoc: non permanent infrastructure mode: permanently on network
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Interface Software
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page description language (PDL): determines how efficient the printer is at converting info to be printed into signals printer can understand Driver software: understands and controls printer
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PDL
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page description language: describes a whole page being printed by sending commands that describe the text as well as margins and other settings controller interprets signals into laser pulses printer languages: PostScript, Printer Command Language (PCL), Graphics Device Interface (GDI) PostScript: developed by Adobe, printer driver describes page in terms of draw and position commands, page is divided into grid, gives start and end points to draw from and to move some processing power from comp to printer
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Driver Software
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controls how printer processes the print job must be for OS and printer configured to use a specific PDL
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Installing and Sharing Printers
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connect to device, install and update driver, calibrate device, configure options and settings, print test page, verify compatibility with OS and device, educate users about functionality
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Installing and Sharing Networked Printers
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making print server part of printer itself, or making it a separate network device
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Print Server
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device that hosts the printer and processes the necessary printer commands
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Local Network Printing
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accessible to others on the network printer needs to be attached to network need to tell computer printer is networked, not local
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Integrated print server
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printer itself has print server
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TCP Printing
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printers that are networked need IP addresses adding a printer via TCP RAW: Standard TCP/IP Port Monitor and is default, port 9100, uses SNMP for bidirectional communication between comp and printer LPR: older, ports 721 - 731, destination is 515 allows clients with different OSs print, sends job directly to printer
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Bonjour
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Apple introduced in 2002, zero configuration networking designed to enable automatic discovery of devices and services using TCP/IP and to provide hostname resolution
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AirPrint
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print from iPhone, iPod, iPad no drivers on client side
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Cloud Printing
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printing to a remote device setup printer in cloud
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Data Privacy Concerns with Networked Printing
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secure printing: indicate its a private print job, must enter a PIN, then print, must enter PIN on printer before it prints deselect keep print job
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Printer Maintenance
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use authorized parts, replace consumables Paper: composition, basis weight (weight of a ream (500 pieces)), caliper (thickness of sheet) Ink and Toner: always buy exact model printer calls for, use authorized ink
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Printer Scheduled Maintenance
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look for quoted monthly volume of print capacity printers keep track of the number of pages they print use maintenance kit from manufacturer, reset page count in menu run cleaning sequence every time you replace ink
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Ensure a suitable environment for printer
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ensure laser printers are in well-ventilated areas reduce humidity don't open toner cartridges reduce ozone by replacing ozone filter every so often don't use ammonia
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Installing Printer Upgrades
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memory, network cards, firmware
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Printer Memory
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buy only compatible memory make sure it can be upgraded
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Printer NIC
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proprietary, NIC has small processor faster, more efficient printing
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Upgrading Printer Firmware
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download from manufacturer's website offers new features
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Other Upgrades
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printer-resident fonts, need hard drive to store them trays and feeders expansions finisher: stapling, hole punching, folding, sorting, collating
