Describe factors which affect the quality of computer input and output devices. Give practical examples where appropriate.
Output is data that has been processed into a useful form called information. Four types of output are text, graphics, audio, and video.
An output device is any computer component capable of conveying information to a user.
Identify the different types of display devices
A display device is an output device that visually conveys text, graphics, and video information. Information shown on a display device is called soft copy because the information exists electronically and is displayed for a temporary period of time. Display devices include CRT monitors, LCD monitors and displays, gas plasma monitors, and televisions.
factors that affect the quality of a display device
The quality of a CRT monitor depends largely on its resolution, dot pitch, and refresh rate. The quality of an LCD monitor or display depends primarily on its resolution.
A CRT monitor’s screen is coated with tiny dots of phosphor material, called pixels, that glow when electrically charged to produce an image.
The resolution of an LCD monitor or display generally is proportional to the size of the monitor or display. That is, the resolution increases for larger monitors and devices.
Identify monitor ergonomic issues
The goal of ergonomics is to incorporate comfort, efficiency, and safety into the design of items in the workplace. Features that address monitor ergonomic issues include controls to adjust the brightness, contrast, positioning, and height and width of images. Newer monitors have digital controls that allow you to fine-tune the display. Many monitors also have a tilt and swivel base so the angle of the screen can be altered to minimize neck strain and glare. Monitors produce a small amount of electromagnetic radiation (EMR), which is a magnetic field that travels at the speed of light. High-quality monitors should comply with MPR II, a standard that defines acceptable levels of EMR for a monitor.
Differences among various types of printers
A printer is an output device that produces text and graphics on a physical medium such as paper or transparency film. Printed information is called hard copy because the information exists physically and is a more permanent from of output. Printers can be grouped in two categories: impact and nonimpact.
Impact printers form characters and graphics by striking a mechanism against an ink ribbon that physically contacts the paper.
Nonimpact printers form characters and graphics without actually striking the paper.
Some printers are used for special purposes.
Factors affect the printer quality
Choice of Ink
· Two types of ink are mainly used in inkjet printers - dye based and pigments based inks. Read about the characteristics of these ink types in our printer ink article.
Choice of Paper
· Glossy papers and paper with optical brighteners can react badly to particles in the air and ultraviolet light. This will have a negative effect on the long term printout quality.
· The solution is to use premium archival printer paper that has been developed to be more fade resistant than ordinary printer paper. A premium printer paper is built up by different layers that all have their own purpose such as controlling the ink absorption, keeping moisture out, wrinkling resistance and creating a paper surface with the right characteristics and looks. If you want to be certain of the produced results, go for a paper and ink type that the original printer manufacturer recommends. Tip: Read our article about inkjet photo paper.
· If you store your printouts in direct light they will fade with time, the more intense the light is the faster the fading process will be. The solution is to store your printouts in a dark, dry and cool place. Modern inks such as HP Vivera Inks are made to resist the effects of direct sunlight, ultraviolet light and incandescent light.
· Dye based printouts with higher concentration of cyan color tones react badly to airborne chemicals and especially to ozone. The solution is to store them in a protected atmosphere which could mean storing them under plastic or glass. The plastic should be acid and lignin free in order to not react with the printout.
Heat and Humidity exposure
· Extensive heat will have an effect on both the paper and the ink dissolving the printout in the worst case. To high humidity may cause dye based inks to "move". What happens is that individual colors (i.e. dyes) may move at a different speed making the color balance and sharpness of the printout to deteriorate. It's recommended that you store your printouts in a dry and cool temperature that doesn't fluctuate too much.
Uses of speakers and headsets
An audio output device produces music, speech, or other sounds. Two commonly used audio output devices are speakers and headsets.
Data projectors, fax machines, and multifunction devices
A data projector takes the image on a computer screen and projects it onto a large screen so that an audience of people can see the image. Two smaller, lower priced data projectors are an LCD projector, which uses liquid crystal display technology, and a digital light processing (DLP) projector, which uses tiny mirrors.
A facsimile (fax) machine transmits and receives documents over telephone lines. A fax modem is a communication device that allows you to send (and sometimes receive) electronic documents as faxes.
A multifunction device (MFD) is a single piece of equipment that looks like a copy machine but provides the functionality of a printer, scanner, copy machine, and sometimes a fax machine.
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