This chapter covers the four major printer technologies tested on the CompTIA A+ 220-1101 exam: laser, inkjet, thermal, and impact. You will learn the internal components, the step-by-step imaging process, and common maintenance tasks for each type. Printer questions appear frequently on the exam, typically accounting for 5-10% of total questions. Mastering these technologies is essential for troubleshooting and supporting printers in any IT environment.
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Imagine a busy print shop with four distinct machines. The laser printer is like a photocopier that uses a drum and toner powder: it charges a drum, draws an image with a laser, attracts toner to the charged areas, transfers it to paper, and fuses it with heat. The inkjet printer is like a precise spray painter: it uses tiny nozzles to spray liquid ink droplets onto paper in exact patterns. The thermal printer is like a receipt printer that uses heat to activate special paper or transfer wax from a ribbon. The impact printer is like a typewriter: it uses a print head with pins that strike an ink ribbon to imprint characters onto paper. Each technology has its own strengths: laser for speed and volume, inkjet for color quality and photos, thermal for quiet and low-cost receipts, impact for multipart forms. The exam expects you to know their components, processes, and typical uses.
Overview of Printer Technologies
Printers convert digital data into physical output. The 220-1101 exam focuses on four main technologies: laser, inkjet, thermal, and impact. Each uses a different mechanism to apply ink or toner to paper. Understanding these mechanisms is critical for installation, configuration, and troubleshooting.
Laser Printers
Laser printers use electrophotographic (EP) imaging. They produce high-quality text and graphics quickly and are common in office environments.
Key Components: - Toner cartridge: Contains toner powder (a mixture of plastic particles, carbon, and coloring agents). - Drum unit: A photosensitive drum that holds an electrostatic charge. - Corona wire (or primary charge roller): Applies a uniform negative charge to the drum. - Laser scanning unit: Uses a laser beam to discharge specific areas on the drum, creating a latent image. - Developer roller: Transfers toner to the discharged areas on the drum. - Transfer roller: Applies a positive charge to the paper to attract toner from the drum. - Fuser assembly: Heats and presses the toner onto the paper (typically around 200°C / 392°F). - Waste toner bottle: Collects excess toner. - Ozone filter: Removes ozone produced by the corona wire.
Imaging Process (6 steps): 1. Cleaning: The drum is physically cleaned of residual toner and electrically erased by a discharge lamp. 2. Conditioning (charging): The corona wire or primary charge roller applies a uniform negative charge (typically -600V to -1000V) to the drum. 3. Writing (exposing): The laser beam scans the drum, discharging specific areas to near 0V, creating a latent electrostatic image. 4. Developing: Toner, which is negatively charged, is attracted to the discharged (less negative) areas on the drum. The developer roller applies a thin layer of toner. 5. Transferring: The paper is given a positive charge by the transfer roller, pulling the negatively charged toner from the drum onto the paper. 6. Fusing: The paper passes through heated rollers (the fuser) at around 200°C, melting the toner particles and bonding them to the paper.
Common Maintenance: Replace toner cartridge, drum unit, fuser, and transfer roller. Clean corona wires or replace charge rollers. Empty waste toner bottle. Replace ozone filter.
Exam Tips: - Remember the order: Cleaning, Conditioning, Writing, Developing, Transferring, Fusing. - The laser writes the image; the transfer roller moves toner to paper. - Fuser uses heat and pressure.
Inkjet Printers
Inkjet printers spray tiny droplets of liquid ink onto paper. They are popular for home use and color printing.
Key Components: - Print head: Contains nozzles (often hundreds) that eject ink. - Ink cartridges: Hold liquid ink (dye-based or pigment-based). Some printers have separate cartridges for each color (CMYK: Cyan, Magenta, Yellow, Black). - Carriage and belt: Moves the print head across the paper. - Paper feed mechanism: Uses rollers to pull paper through. - Stepper motor: Controls carriage movement. - Encoder strip: Provides position feedback for the print head.
Imaging Process: 1. The print head moves across the paper in a series of passes. 2. Ink is ejected through nozzles using either thermal or piezoelectric technology. - Thermal inkjet: A tiny resistor heats the ink, creating a bubble that forces ink out of the nozzle. - Piezoelectric inkjet: A crystal vibrates to push ink out (used in Epson printers). 3. The paper advances slightly after each pass. 4. Multiple passes build up the image.
Common Maintenance: - Print head cleaning: Use the printer's utility to clear clogged nozzles. - Ink cartridge replacement: Ensure genuine cartridges for best quality. - Calibration: Align print heads for accurate color. - Paper jams: Clear jammed paper carefully.
Exam Tips: - Know the difference between thermal and piezoelectric inkjet. - Inkjet printers are slower than laser but produce excellent photo quality. - Dye-based inks are more vibrant but less water-resistant; pigment-based inks are more durable.
Thermal Printers
Thermal printers use heat to produce images on special paper. They are common in point-of-sale (POS) systems, label printers, and fax machines.
Types: - Direct thermal: Uses heat-sensitive paper that darkens when heated. No ribbon or ink. Examples: receipt printers, shipping labels. - Thermal wax transfer: Uses a ribbon coated with wax-based ink. Heat melts the wax onto the paper. Produces more durable prints. - Thermal dye sublimation: Uses a ribbon with dye. Heat turns dye into gas that permeates the paper. Produces continuous-tone photo-quality prints.
Key Components: - Thermal print head: Contains a row of tiny heating elements (resistors). - Platen roller: Pushes paper against the print head. - Paper sensor: Detects paper presence and alignment. - Stepper motor: Advances paper. - Ribbon (for transfer types): Carries wax or dye.
Imaging Process (Direct Thermal): 1. Paper is fed between the print head and platen roller. 2. The print head selectively heats specific elements. 3. Heat causes the paper coating to turn black (or another color) in those areas. 4. The paper advances for the next line.
Common Maintenance: - Clean the print head with isopropyl alcohol and a lint-free cloth. - Replace the platen roller if worn. - Use the correct paper type (coated for direct thermal).
Exam Tips: - Direct thermal prints fade over time; thermal wax transfer is more durable. - Thermal printers are quiet and have few moving parts. - They are used for receipts, labels, and tickets.
Impact Printers
Impact printers use a print head that strikes an ink ribbon to transfer ink to paper. They are noisy but can print through multipart forms (e.g., carbon copies).
Types: - Dot-matrix printers: Use a print head with a matrix of pins (e.g., 9-pin or 24-pin). Pins strike the ribbon to form characters or graphics. - Daisy-wheel printers: Use a wheel with raised characters. The wheel rotates to the correct character, then a hammer strikes it against the ribbon. (Less common today.)
Key Components: - Print head: Contains pins arranged in a column. - Ribbon: An ink-soaked fabric or film that transfers ink to paper. - Platen: A roller that holds paper and advances it. - Paper feed mechanism: Tractor feed (using sprocket holes) or friction feed. - Stepper motor: Moves the print head and advances paper.
Imaging Process (Dot-Matrix): 1. The print head moves across the paper in a series of passes. 2. Pins fire in patterns to form characters or graphics. 3. Each pin strikes the ribbon, pressing it against the paper. 4. The ribbon transfers ink to the paper. 5. The paper advances for the next line.
Common Maintenance: - Replace the ribbon when it fades. - Clean the print head pins with isopropyl alcohol. - Adjust print head gap for paper thickness. - Replace the platen if worn.
Exam Tips: - Impact printers are the only type that can print multipart forms (carbon copies). - They are noisy and produce low-resolution output. - Dot-matrix printers use tractor feed for continuous paper.
Comparison Summary
| Feature | Laser | Inkjet | Thermal | Impact | |---------|-------|--------|---------|--------| | Print speed | Fast (20+ ppm) | Slow to moderate (5-15 ppm) | Moderate (depends on ribbon) | Slow (5-10 cps) | | Print quality | High (text and graphics) | High (photos) | Medium (direct thermal fades) | Low (dot matrix) | | Cost per page | Low (black) | High (color ink) | Low (direct thermal) | Low (ribbon) | | Noise | Moderate | Low | Low | High | | Multipart forms | No | No | No | Yes | | Common use | Office documents | Home photos, small office | Receipts, labels | Invoices, shipping |
Troubleshooting Common Printer Issues
Laser: Blank pages (check toner, drum, transfer roller); smudges (dirty fuser or drum); vertical lines (scratched drum or dirty corona wire); paper jams (worn rollers).
Inkjet: Streaks (clogged nozzles, run cleaning cycle); color missing (empty cartridge); paper jams (misaligned paper).
Thermal: Faint print (dirty print head, low voltage); paper jam (platen roller worn).
Impact: Faint print (ribbon worn); missing dots (pins broken); paper not feeding (tractor feed misaligned).
Configuration and Connectivity
Printers connect via USB, Ethernet, Wi-Fi, Bluetooth, or parallel (legacy). Network printers are configured with an IP address (static or DHCP). For shared printers, set up print server. Use the printer's web interface for advanced settings like duplex, paper size, and quality.
Exam Focus
The 220-1101 exam tests:
The 6-step laser printer process (order and what happens at each step).
Key components: toner, drum, fuser, corona wire, transfer roller.
Differences between printer types: which is best for multipart forms (impact), which uses heat-sensitive paper (thermal direct), which uses liquid ink (inkjet), which uses toner (laser).
Maintenance tasks: replacing toner, cleaning print heads, replacing ribbons, cleaning thermal print heads.
Troubleshooting: what causes blank pages, smudges, streaks, or faded prints.
Common wrong answers:
Confusing the transfer roller with the fuser (transfer roller moves toner to paper; fuser bonds it).
Thinking laser printers use liquid ink (they use toner powder).
Believing thermal printers always use ribbons (direct thermal does not).
Assuming impact printers are obsolete (they are still used for multipart forms).
Laser Printer: Cleaning Phase
The cleaning step removes residual toner and electrical charge from the drum after the previous print cycle. A rubber blade physically scrapes off any toner left on the drum, and a discharge lamp (or erase lamp) neutralizes any remaining electrostatic charge on the drum surface. This ensures the drum starts each new print job with a clean, neutral state. Without proper cleaning, ghost images from previous prints would appear, and the charge would be uneven. The waste toner is collected in a waste toner bottle, which must be emptied periodically. This step occurs first in the laser printing process.
Laser Printer: Conditioning Phase
During conditioning, the primary corona wire or charge roller applies a uniform negative charge (approximately -600V to -1000V) to the entire surface of the photosensitive drum. This charge makes the drum ready to be selectively discharged by the laser. The charge is applied evenly across the drum's surface. In some printers, a primary charge roller (PCR) replaces the corona wire to reduce ozone production. The voltage level must be precise; if too low, toner transfer may be poor; if too high, the drum may be damaged.
Laser Printer: Writing Phase
The writing phase uses a laser beam to create a latent electrostatic image on the drum. The laser scans across the drum's surface, turning on and off according to the digital image data. Where the laser strikes the drum, it discharges the negative charge to near 0V. The areas not hit by the laser remain at the high negative voltage. This creates an invisible image of the page on the drum. The laser is controlled by a rotating mirror and lenses to ensure precise positioning. The resolution is determined by the laser's dot size and scanning accuracy.
Laser Printer: Developing Phase
In the developing phase, toner is applied to the drum. The toner in the cartridge is negatively charged (like the drum). The developer roller, which is part of the toner cartridge, presents a thin layer of toner to the drum. The drum's discharged areas (where the laser hit) have a lower negative charge, so the negatively charged toner is repelled from the highly negative areas and attracted to the discharged areas. The toner particles adhere electrostatically to the latent image. The developer roller also ensures an even toner layer. The amount of toner transferred is controlled by the bias voltage on the developer roller.
Laser Printer: Transferring Phase
During transfer, the toner image on the drum is moved to the paper. The paper is fed between the drum and the transfer roller. The transfer roller applies a strong positive charge to the paper. Since the toner is negatively charged, it is attracted to the positively charged paper. The paper picks up the toner from the drum. The drum then continues rotating, and any residual toner is cleaned off in the next cleaning phase. The transfer charge must be carefully controlled to avoid paper curl or toner scattering. After transfer, the paper holds the toner image loosely.
Laser Printer: Fusing Phase
The final step is fusing, where the toner is permanently bonded to the paper. The paper passes through the fuser assembly, which consists of two heated rollers: a upper roller (with a non-stick coating like Teflon) and a lower pressure roller. The upper roller is heated to around 200°C (392°F). The heat melts the toner particles, and the pressure from the rollers presses the molten toner into the paper fibers. As the paper exits the fuser, the toner cools and solidifies, creating a permanent image. If the fuser temperature is too low, the toner may smudge; if too high, the paper may wrinkle or the toner may bleed.
Enterprise Laser Printer Deployment
A large law firm deploys networked laser printers (e.g., HP LaserJet Enterprise) for high-volume document printing. Each printer serves up to 50 users and prints thousands of pages per month. The firm uses centralized print management software to enforce duplex printing (saves paper), track usage by department, and automatically order toner when low. Printers are configured with static IP addresses and connected via Gigabit Ethernet. Maintenance includes replacing toner cartridges every 5,000-10,000 pages, replacing the fuser every 100,000 pages, and cleaning the corona wires quarterly. A common issue is paper jams caused by worn pickup rollers, which are replaced as part of a preventive maintenance kit.
Retail Environment with Thermal Printers
A national retail chain uses direct thermal printers for receipt printing at point-of-sale (POS) terminals. The printers are compact, quiet, and fast (up to 300 mm/sec). They connect via USB or Ethernet to the POS system. The store stocks thermal paper rolls that are 80mm wide and 80mm diameter. Maintenance involves cleaning the print head with isopropyl alcohol every 1,000 receipts to prevent buildup of paper residue. A common problem is faded prints due to a dirty print head or low voltage. The IT team monitors printer health via SNMP and receives alerts when paper is low.
Impact Printers for Multipart Forms
A logistics company uses dot-matrix impact printers to print shipping labels and invoices on multipart carbonless forms. The printers use tractor feed to handle continuous paper with sprocket holes. The print head is a 24-pin model for better quality. Ribbons are replaced every 3 million characters. The printers are connected via parallel ports (legacy) or USB-to-parallel adapters. A common issue is paper jams due to misaligned tractor feed or worn platen. The company keeps spare print heads and ribbons on hand. Impact printers are chosen because laser and inkjet cannot print through multiple copies.
What the 220-1101 Tests
Objective 3.8: Given a scenario, install and configure printers. The exam tests knowledge of printer types, their components, the imaging process (especially laser), maintenance procedures, and troubleshooting. Specific areas: - Laser printer steps: Know the order (Cleaning, Conditioning, Writing, Developing, Transferring, Fusing) and what happens in each step. Expect a question asking 'Which step applies toner to the drum?' (Developing). - Components: Identify toner cartridge, drum, fuser, corona wire, transfer roller, print head, ribbon, platen. - Printer types: Which uses toner? (Laser). Which uses liquid ink? (Inkjet). Which uses heat-sensitive paper? (Thermal direct). Which uses a ribbon? (Impact and thermal transfer). Which can print multipart forms? (Impact). - Maintenance: What to replace when prints are faint (toner/ribbon), have streaks (clean print head or drum), or have smudges (fuser). - Connectivity: USB, Ethernet, Wi-Fi, Bluetooth, parallel. Know that network printers require an IP address.
Common Wrong Answers
Confusing toner and ink: Many candidates think laser printers use ink. The exam will ask 'Which printer uses toner?' and the wrong answer might be 'inkjet'. Remember: toner is powder, ink is liquid.
Mixing up transfer roller and fuser: The transfer roller moves toner to paper; the fuser bonds it. A question might ask 'Which component applies heat to fuse toner?' The wrong answer could be 'transfer roller'.
Thinking all thermal printers use ribbons: Direct thermal uses no ribbon; thermal wax transfer does. The exam may ask 'Which thermal printer type does not require a ribbon?' Answer: direct thermal.
Assuming impact printers are obsolete: They are still used for multipart forms. A scenario question might describe a need for carbon copies; the correct answer is impact printer.
Specific Numbers and Terms
Laser fuser temperature: ~200°C (392°F).
Corona wire voltage: -600V to -1000V.
Common pin counts for dot-matrix: 9-pin, 24-pin.
Thermal paper width: often 80mm for receipts.
Laser printer steps: Cleaning, Conditioning, Writing, Developing, Transferring, Fusing (some sources say Cleaning, Charging, Exposing, Developing, Transferring, Fusing).
Edge Cases
Laser printer prints blank pages: Possible causes: empty toner, faulty drum, transfer roller not engaging, or high-voltage power supply failure.
Inkjet prints blank pages: Clogged print head, empty ink cartridge, or print head not installed.
Thermal printer prints blank: Wrong paper type (not thermal), dirty print head, or print head ribbon (if transfer type) broken.
Impact printer prints faint: Ribbon worn out, print head gap too wide, or ribbon not advancing.
How to Eliminate Wrong Answers
Read the question carefully for clues: 'multipart forms' → impact; 'quiet operation' → inkjet or thermal; 'fast text printing' → laser; 'photo quality' → inkjet; 'low cost per page for black' → laser; 'no ribbon or ink' → direct thermal. Use the process of elimination based on these keywords.
Laser printer imaging process order: Cleaning, Conditioning, Writing, Developing, Transferring, Fusing.
Laser printers use toner (powder); inkjet printers use liquid ink.
Direct thermal printers use heat-sensitive paper and no ribbon; thermal wax transfer uses a ribbon.
Impact printers are the only type capable of printing multipart forms (carbon copies).
Common laser printer maintenance: replace toner, drum, fuser; clean corona wires; empty waste toner.
Inkjet maintenance: clean print head, replace ink cartridges, calibrate print heads.
Thermal printer maintenance: clean print head with isopropyl alcohol, replace platen roller if worn.
Impact printer maintenance: replace ribbon, clean print head pins, adjust print head gap.
These come up on the exam all the time. Here's how to tell them apart.
Laser Printer
Uses toner powder
Faster for high-volume text
Higher initial cost, lower cost per page
Better for black-and-white documents
Requires fuser maintenance
Inkjet Printer
Uses liquid ink
Better for photo-quality color
Lower initial cost, higher cost per page
More prone to clogged nozzles
Requires print head cleaning
Mistake
Laser printers use liquid ink.
Correct
Laser printers use toner, which is a fine powder made of plastic, carbon, and coloring agents. Inkjet printers use liquid ink.
Mistake
The fuser transfers toner to the paper.
Correct
The transfer roller transfers toner to the paper. The fuser then heats and presses the toner to bond it permanently.
Mistake
All thermal printers require a ribbon.
Correct
Direct thermal printers use heat-sensitive paper and do not require a ribbon. Thermal wax transfer and dye sublimation printers use a ribbon.
Mistake
Impact printers are completely obsolete.
Correct
Impact printers are still used for multipart forms (e.g., carbon copies) because they physically strike the paper through multiple layers. Laser and inkjet cannot do this.
Mistake
Inkjet printers are faster than laser printers.
Correct
Laser printers are generally faster for text and graphics, printing 20+ pages per minute. Inkjet printers are slower, typically 5-15 ppm.
Reveal each answer, then mark whether you got it right. Score 60%+ to unlock the next chapter.
The correct order is: 1) Cleaning, 2) Conditioning (charging), 3) Writing (exposing), 4) Developing, 5) Transferring, 6) Fusing. Some sources use slightly different names (e.g., 'Exposing' for Writing), but the order is the same. The exam expects you to know this sequence.
Impact printers (specifically dot-matrix) are best for printing multipart forms because they use physical impact to transfer ink through multiple layers of paper. Laser and inkjet printers cannot print through carbon copies.
Vertical streaks are often caused by a scratched drum, a dirty corona wire, or a damaged fuser. If the streak repeats at intervals matching the drum circumference, the drum is likely damaged. If the streak is constant, the corona wire may be dirty.
Missing colors are usually due to a clogged print head nozzle or an empty ink cartridge. Run the printer's cleaning utility to clear clogs. If that fails, replace the cartridge. Also ensure the correct paper type is loaded.
Turn off the printer and open the cover. Use a lint-free cloth or cotton swab lightly moistened with isopropyl alcohol (90% or higher) to gently wipe the print head. Allow it to dry completely before closing. Do not use abrasive materials.
Direct thermal uses heat-sensitive paper that darkens when heated; no ribbon is needed. Thermal wax transfer uses a ribbon coated with wax-based ink; heat melts the wax onto plain paper. Direct thermal prints fade over time; thermal wax transfer is more durable.
Fuser replacement intervals vary by printer model, but typically every 100,000 to 200,000 pages. Check the printer's maintenance guide. Signs of a failing fuser include smudged prints, paper jams, or a burning smell.
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