Lesson 10

barcode scanner

A barcode is a pattern of different sized parallel bars, typically representing a product number, such as an ISBN, IAN/EAN, or UPC. The reader uses a sensor mechanism (one of a photo diode, laser, or CCD) to read the intensity of light reflected back by the barcode. The reader then reports the number back to application software, which links it to a product database. Barcode scanners are connected to a computer using a USB port.

PIEZOELECTRIC PRINT HEADS

In the Epson design, the nozzle contains a piezoelectric element, which changes shape when a voltage is applied. This acts like a small pump, pushing ink through the nozzle and drawing ink from the reservoir.

Page Description Language (PDL)

Software that tells a printer how to lay out the contents of a printed page.

media guides

The paper transport mechanism includes components such as gears, pads, and rollers that move the paper through the printer. Paper loaded into a tray should be held by media guides. The printer uses sensors from the guides to detect the paper type.

Network Attached Storage (NAS)

a server that is placed on a network with the sole purpose of providing storage to users, computers, and devices attached to the network

contact image sensor

based scanners use an array of LEDs (Light Emitting Diodes) that strobe between red, green, and blue light to illuminate the image. This is reflected via a rod-shaped lens onto an image sensor. CIS scanners are typically used in sheet-fed scanners

printer

is a device that produces text and images from electronic data onto physical media such as paper, photo paper, and labels.

led printers

A traditional laser printer uses a laser with a rotating mirror and prisms to scan across each raster line. An LED printer uses a fixed array of tiny Light Emitting Diodes (LED) to create the light pulses for each dot in each scan line.

speed

The basic speed of a printer is measured in Pages Per Minute (ppm). You will see different speeds quoted for different types of output (for example, pages of monochrome text will print more quickly than color photos).

quick response (QR) code

are a particular type of 2D barcode that have been widely adopted for consumer-oriented uses. A QR code can be scanned using a smart phone camera, a normal digital camera, or webcam. There is no need to install special barcode scanning hardware. QR code scanning software can identify a QR code image directly from the camera and initiate the appropriate response in software to the information contained in the QR code. This might be to open a website or import a contact record or calendar event

3d printing

builds a solid object from successive layers of material. The material is typically some sort of plastic but there are printer types that can work with rubber, carbon fiber, or metal alloys too

scanner

is a digital imaging device, designed to create computer file data from a real-life object. Typically, scanners handle flat objects, like documents, receipts, or photographs.

thermal printer

is a general term for any printer that uses a heating element to create the image on the paper with dye, ink from ribbons, or directly with pins while the feed assembly moves the media through the printer.

maintenance kit

is a set of replacement feed rollers, new transfer roller, and a new fuser unit. The feed rollers guide paper through the printer assembly. When they begin to wear out, paper jams become more frequent. Wear on the fuser or rollers is also evidenced by consistent marks on print output or excess toner "blobs" appearing on sheets.

platen gap

is the distance between the print head and the paper. Having an adjustable platen gap allows the printer to use thicker media.

printer type or printer technology

is the mechanism used to make images on the paper. The most common types for general home and office use are inkjet (or inkdispersion) and laser, though others are used for more specialist applications.

Backed up print queue

means that there are lots of jobs pending but not printing.

inkjet

or more generally ink dispersion—printer forms images by firing microscopic droplets of liquid ink out of nozzles mounted together on a carriage assembly that moves back and forth across the paper. The printer can use heat or vibrations to release the ink.

print driver

provides an interface between the print device and Windows.

Optical Character Recognition (OCR)

software can be used to convert scanned text into digital documents, ready for editing.

print monitor

transmits the print job to the printer and provides status information. Most print devices have their own memory and processor, enabling the print job to be transmitted more quickly and reliably.

flatbed scanner

works by shining a bright light, usually from a Cold Cathode Fluorescent Lamp (CCFL), at the object, which is placed on a protective glass surface. A system of mirrors reflects the illuminated image of the object onto a lens. The lens either uses a prism to split the image into its component colors (Red, Green, and Blue) or focuses it onto imaging sensors coated with different color filters.

Internet Printing Protocol (IPP)

A protocol that is encapsulated in HTTP and that is used to print files over the Internet.

CMYK (Cyan, Magenta, Yellow, and Black [K]).

Color images are created by combining four inks

Charging Corona

On most modern printers, the function of the charging corona wire is actually performed by a metal roller with a rubber coating—the Primary Charge Roller (PCR).

electrostatic latent image

A laser neutralizes the charge that was applied by the corona wire selectively, dot-by-dot and line-by-line, as the drum rotates. The laser-scanning assembly houses a small, low-power laser, similar to that used in an optical drive. As the laser receives the image information, it fires a short pulse of light for each dot in the raster. The pulsing light beam is reflected by a rotating polygonal mirror through a system of lenses onto the photosensitive drum. The drum ends up with a whole series of raster lines with charge/no-charge areas that represent an electrostatic latent image of the image to be printed.

laser printers

A laser printer is a printer that uses a laser beam to project (or "draw") a latent image onto an electrically charged drum; toner adheres to the drum and is transferred onto the paper as the paper moves through the mechanism at the same speed the drum rotates. The toner is fixed using high heat and pressure, creating a durable printout that does not smear or fade.

hard copy

A printer output of electronic documents

interfaces

Almost all printers support USB, but printer models designed for workgroups also support network connections, usually at a higher cost than standard models. Wireless connections may also carry a price premium.

multi function device

An MFD is a piece of office equipment that performs the functions of a number of other specialized devices. MFDs typically include the functions of a printer, scanner, fax machine, and copier. However, there are MFDs that do not include fax functions. Although the multifunction device might not equal the performance or feature sets of the dedicated devices it replaces, multi-function devices are very powerful and can perform most tasks adequately and are an economical and popular choice for most home or small-office needs.

paper transferring process

Different trays may support different types, sizes, and thicknesses of media. Pickup components lift a single sheet of paper from the selected input tray and feed it into the printer. To do this, a pickup roller turns once against the paper stack, pushing the paper into a feed and separation roller assembly (the manual feed tray uses a separation pad rather than rollers). This assembly is designed to allow only one sheet to pass through.

Windows Presentation Foundation (WPF)

Display and print functions for compatible applications are handled by the Windows Presentation Foundation (WPF). A WPF print job is formatted and spooled as an XML Print Specification (XPS) file in the printer's spool folder (%SystemRoot% \System32\Spool\Printers\).

laser printer imaging process

In the laser printing process, laser printers print a page at a time using a combination of electrostatic charges, toner, and laser light. The computer encodes the page in a printer language and sends it to the printer. The printer's formatter board processes the data to create a bitmap (or raster) of the page and stores it in the printer's RAM. The entire laser printer cycle takes place in one smooth sequence but, since the circumference of the drum that processes the image is smaller than a sheet of paper, the process must be repeated 2-4 times (according to size) to process a single page.

developer roller

Laser (and photocopier) toner is composed of a fine compound of dyestuff and either wax or plastic particles. The toner is fed evenly onto a magnetized roller (the developer roller) from a hopper. The developer roller is located very close to the photosensitive drum. The toner carries the same negative charge polarity as the drum, which means that, under normal circumstances, there would be no interaction between the two parts. However, once areas of charge have been selectively removed from the photosensitive drum by the laser, the toner is attracted to them and sticks to those parts of its surface. The drum, now coated with toner in the image of the document, rotates until it reaches the paper.

paper handling

Paper handling means the type of paper or media that can be loaded. It may be important that the printer can handle labels, envelopes, card stock, acetate, and so on. The amount of paper that can be loaded and output is also important in high volume environments. Overloaded output trays will cause paper jams. If the output tray is low capacity, this could happen quite quickly in a busy office.

total cost of ownership

TCO is the cost of the printer over its lifetime, including the cost of replacement components and consumables.

image quality

The basic measure of image quality is the maximum supported resolution, measured in dots per inch (dpi). Printer dots and screen image pixels are not equivalent. It requires multiple dots to reproduce one pixel at acceptable quality. Pixel dimensions are typically quoted in pixels per inch (ppi) to avoid confusion. Vertical and horizontal resolution are often different, so you may see figures such as 2400x600 quoted. The horizontal resolution is determined by the print engine (that is, either the laser scanning unit or inkjet print head); vertical resolution is determined by the paper handling mechanism. The minimum resolution for a monochrome printer should be 600 dpi. Photo-quality printers start at 1200 dpi.

fuser assembly

The fuser unit squeezes the paper between a hot roller and a pressure roller so that the toner is fused, or melted, onto the surface of the paper. The hot roller is a metal tube containing a heat lamp; the pressure roller is typically silicon rubber. The heat roller has a Teflon coating to prevent toner from sticking to it.

Ink Delivery Systems (IDS)

There are two main Ink Delivery Systems (IDS). The charge (or piezoelectric) method is used by Epson. The thermal method is used by HP, Canon (who refer to it as Bubblejet), and Lexmark.

printer cleaning

To complete the printing cycle, the photosensitive drum is cleaned to remove any remaining toner particles using a cleaning blade, roller, or brush resting on the surface of the drum. Any residual electrical charge is removed using either a discharge (or erase lamp) or the primary charge roller.

process with the register and transfer roller

When the paper reaches the registration roller, a signal tells the printer to start the image development process. When the drum is ready, the paper is fed between the photosensitive drum and the high voltage transfer roller (or secondary corona). The transfer roller applies a positive charge to the underside of the paper. This causes the toner on the drum to be attracted to the paper. As the paper leaves the transfer assembly, a static eliminator strip (or detac corona) removes any remaining charge from the paper, which might otherwise cause it to stick to the drum or curl as it enters the fuser unit.

thermal print heads

With the thermal method, the ink at the nozzle is heated, creating a bubble. When the bubble bursts, it sprays ink through the nozzle and draws more ink from the reservoir.

laser printer toner

is a fine powder made of particles of iron, carbon, and resin. Refill or recycle empty toner cartridges; do not dispose of them in regular trash.

electrostatic photographic (EP) drum, or imaging drum

is conditioned by a corona wire powered by a high voltage power supply assembly. The corona wire applies a uniform -600 V electrical charge across the drum's surface. A laser printer has a power supply capable of generating very high voltages. It converts the supplied current to optimal AC and DC voltages for specific components, such as the corona wire.

calibiration

is the process by which the printer determines the appropriate print density or color balance (basically, how much toner to use). Most printers calibrate themselves automatically. If print output is not as expected, you can often invoke the calibration routine from the printer's control panel or its software driver.

impact printer

strikes an inked ribbon against paper to leave marks. One common type is the dot matrix printer, which uses a column of pins (also called print wires) to strike the ribbon.

tractor feeds

uses pairs of wheels with pins evenly spaced around the circumference at a set spacing. Continuous-roll paper with matching holes in the edges fits over the pins. The wheels turn and pull the paper through the printer. There are usually just two wheels, but there might be additional wheels or pin guides that the paper is latched to. There is usually a lever or other setting on the printer that needs to be engaged in order to use the tractor feed.