Printers are a type of computer peripheral device that fall into two broad categories: 2D printers that print text and graphics onto paper (or other media) and 3D printers that create physical objects.
Common Types of 2D Printers
2D printers are by far the most common type of printer. This category can be subdivided based on the type of technology used to transfer images onto paper. Modern printers generally fall into one of the following categories:
- inkjet: Sprays ink at a sheet of paper. Ink-jet printers produce high-quality text and graphics.
- laser: Uses the same technology as copy machines. Laser printers produce very high quality text and graphics.
- LED: Similar to a laser printer but uses light-emitting diodes rather than a laser to produce an image on the drum.
- thermal printer: Works by pushing heated pins against heat-sensitive paper. Thermal printers are widely used in calculators, ATMs and cash registers.
- dye-sublimation: Uses heat to transfer dye to paper, fabric, plastic cards or other media. These printers are often used to print photos or ID cards.
Old, Outdated and Obsolete Printers
Older printers that are no longer commonly used relied on a number of other technologies, including the following:
- daisy-wheel: Has a plastic or metal wheel on which the shape of each character stands out in relief, similar to a ball-head typewriter. A hammer presses the wheel against a ribbon, which in turn makes an ink stain in the shape of the character on the paper. Daisy-wheel printers produce letter-quality print but cannot print graphics.
- dot-matrix: Creates characters by striking pins against an ink ribbon. Each pin makes a dot, and combinations of dots form characters and illustrations.
- line printer: Contains a chain of characters or pins that print an entire line at one time. Line printers are very fast but produce low-quality print.
- solid ink printer: Uses solid sticks of waxy ink that are melted and sprayed onto the page. Also known as a phase-change printer, this type of device produces high-quality graphics but consumes a lot of energy.
- plotter: Rely on special pens to draw images on the paper. These printers were popular for engineering and architectural applications.
2D Printer Characteristics
2D Printers can also be classified by the following characteristics:
- color: Some printers create only black-and-white images, while others print in full color.
- resolution: Resolution is a measure of how many dots per inch (dpi) the printer can deposit on a page. The higher the resolution, the higher the quality of the printed images, particularly when it comes to photographs.
- quality of type: The text output produced by printers is said to be either letter quality (the best available), near letter quality or draft quality.
- speed: Measured in pages per minute (ppm), the speed of printers varies widely depending on the price of the model and its intended use.
- monthly duty cycle: This characteristic offers an estimate of how many pages the printer can be expected to output per month. In general, home printers have a much lower duty cycle than office or commercial printers.
- warm-up time: Printers that rely on heat to transfer images often require a warm-up period after they have been idle for a while. Manufacturers often specify the warm-up time in seconds or offer estimates for “first page out” times.
- all-in-one capabilities: Many home and office printers incorporate scanner, copier and/or fax capabilities.
- ports and wireless: Some printers have built-in USB or Ethernet ports and/or memory card readers, and some have the ability to connect to wireless networks.
- networking: Some home and small business printers need to be connected directly to a PC, but many office and commercial printers can be accessed through a local area network.
3D printers work by depositing layers of material on top of each other to create a physical object. This type of process is also sometimes called additive manufacturing. Currently, companies are investing in a lot of research and development around 3D printing, and the technology is changing rapidly. 3D printing is expected to grow in popularity as the technology improves and costs for 3D printers decline.
3D Printer technology
Types of 3D printing include the following:
- Digital Light Processing (DLP) uses liquid plastic resin that hardens quickly when affected by large amount of light.
- Direct Metal Laser Sintering (DMLS) fuses powdered metal and alloy materials with a high-wattage laser to produce metal parts.
- Electronic Beam Melting (EBM) uses a metal powder and an electron beam to melt and form a metal part layer by layer.
- Fused Deposition Modeling (FDM) creates parts layer-by-layer with engineering-grade thermoplastics.
- Laser Sintering (LS) uses a CO2 laser to heat and fuse durable thermoplastic powder.
- Laminated Object Manufacturing (LOM) uses layers of adhesive-coated paper and are fused together using heat and pressure and then cut to shape with a computer controlled laser.
- PolyJet uses jets to cure thin layers of liquid photopolymer with UV energy.
- Stereolithography (SLA) builds parts layer-by-layer using a UV laser to solidify liquid photopolymer resins.
A third category of printer — a virtual printer — isn’t actually a device at all but is instead a piece of software that provides an electronic view of how a document would look if printed. Today, virtual printers are most commonly used to create PDF documents, to create an image of the document, or to send an electronic document as a fax. Print services and businesses may also use a virtual printer to preview how a document will look when printed on special stationary or corporate letterhead to test the print before using expensive paper.
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