List and describe the operation of the following display devices;
Video Cards;
A video card, video adapter, graphicsaccelerator card, display adapter or
graphics card is an expansion card whose
function is to generate and output images
to a display. Many video cards offer
added functions, such as accelerated rendering
of 3D scenes and 2D graphics, video capture,
TV-tuner adapter, MPEG-2/MPEG-4 decoding,
FireWire, light pen, TV output, or the ability to
connect multiple monitors (multi-monitor).
Other modern high performance video cards are
used for more graphically demanding purposes,
such as PC games.
LCD Monitors.
A liquid crystal display (LCD) is a thin, flat electronic visual
display that uses the light modulating properties of liquid
crystals (LCs). LCs do not emit light directly. LCDs therefore
need a light source and are classified as "passive" displays. Some
types can use ambient light such as sunlight or room lighting.
There are many types of LCDs that are designed for both special
and general uses. They can be optimized for static text, detailed
still images, or dynamic, fast-changing, video content. They are
used in a wide range of applications including: computer
monitors, television, instrument panels, aircraft cockpit displays,
signage, etc. They are common in consumer devices such as video
players, gaming devices, clocks, watches, calculators, and
telephones. LCDs have displaced cathode ray tube(CRT)
displays in most applications. They are usually more compact,
lightweight, portable, and lower cost. They are available in a
wider range of screen sizes than CRT and other flat panel
displays.
LCDs are more energy efficient, and offer safer disposal, than
CRTs. Its low electrical power consumption enables it to be used
in battery-powered electronic equipment. It is an electronicallymodulated optical device made up of any number of pixels filled
with liquid crystals and arrayed in front of a light source
(backlight) or reflector to produce images in color or
monochrome. The earliest discovery leading to the development
of LCD technology, the discovery of liquid crystals, dates from
1888.[1] By 2008, worldwide sales of televisions with LCD screens
had surpassed the sale of CRT units.
CRT Monitors.
The cathode ray tube (CRT) is a vacuum tube containing an
electron gun (a source of electrons) and a fluorescent screen,
with internal or external means to accelerate and deflect the
electron beam, used to create images in the form of light emitted
from the fluorescent screen. The image may represent electrical
waveforms (oscilloscope), pictures (television, computer
monitor), radar targets and others.
The CRT uses an evacuated glass envelope
which is large, deep, heavy, and relatively
fragile. Display technologies without these
disadvantages, such as flat plasma displays,
liquid crystal displays, DLP, OLED have
replaced CRTs in many applications and are
becoming increasingly common as costs
decline.
Plasma Screens
A plasma display panel (PDP) is a type of
flat panel
display
common to large TV displays (80
cm or larger). Many tiny cells
between just two panels of glass
hold a mixture of noble gases. The
gas in the cells is electrically
turned into a plasma which emits
ultraviolet light which then excites
phosphors to emit visible light.
Plasma displays should not be confused with LCDs, another
lightweight flat screen display using different technology.
Projectors
A video projector takes a video signal and projects the
corresponding image on a projection screen using a lens system.
All video projectors use a very bright light to project the image,
and most modern ones can correct any curves, blurriness, and
other inconsistencies through manual settings. Video projectors
are widely used for conference room presentations, classroom
training, home theatre and live events applications. Projectors
are widely used in many schools and other educational settings,
connected to an interactive white board to interactively teach
pupils.
Interactive whiteboards.
An interactive whiteboard or IWB, is a
large interactive display that connects to a
computer and projector. A projector
projects the computer's desktop onto the
board's surface, where users control the
computer using a pen, finger or other device. The board is
typically mounted to a wall or on a floor stand.
They are used in a variety of settings such as in classrooms at all
levels of education, in corporate board rooms and work groups,
in training rooms for professional sports coaching, broadcasting
studios and more.
Laser printers
A laser printer is a common type of computer
printer that can rapidly produces high quality
text and graphics on plain paper. As with
digital photocopiers and multifunction printers
(MFPs), laser printers employ a xerographic
printing process but differ from analog
photocopiers in that the image is produced
by the direct scanning of a laser beam across
the printer's photoreceptor.
Inkjet Printers;
An inkjet printer is a type of computer printer that reproduces a
digital image by propelling variably-sized droplets of liquid
material (ink) onto a page. Inkjet printers are the most common
type of printer and range from small inexpensive consumer
models to very large and expensive professional machines.[2]
The concept of inkjet printing dates back to the 19th century and
the technology was first developed in the early 1950s. Starting in
the late 1970s inkjet printers that could reproduce digital images
generated by computers were developed, mainly by Epson,
Hewlett-Packard and Canon. In the worldwide consumer market,
four manufacturers account for the
majority of inkjet printer sales: Canon,
Hewlett-Packard, Epson, and
Lexmark..
The emerging ink jet material
deposition market also uses ink jet
technologies, typically piezoelectric
crystals, to deposit materials directly
on substrates
Sound Cards;
A sound card (also known as an audio card) is a computer
expansion card that facilitates the input and output of audio
signals to and from a computer under control of computer
programs. Typical uses of sound cards include providing the
audio component for multimedia applications such as music
composition, editing video or audio, presentation, education, and
entertainment (games). Many computers have sound capabilities
built in, while others require additional expansion cards to
provide for audio capability.
Speakers
Computer speakers, or multimedia speakers, are speakers
external to a computer, that disable the lower fidelity built-in
speaker. They often have a low-power internal amplifier. The
standard audio connection is a 3.5mm (1/8 inch) stereo jack plug
often color-coded lime green (following the PC 99 standard) for
computer sound cards. A plug and socket for a two-wire (signal
and ground) coaxial cable that is widely used to connect analog
audio and video components. Also called a "phono connector,"
rows of RCA sockets are found on the backs of stereo amplifier
and numerous A/V products. The prong is 1/8" thick by 5/16"
long. A few use an RCA connector for input. There are also USB
speakers which are powered
from the 5 volts at 200
milliamps provided by the USB
port, allowing about half a
watt of output power.