gwapo report

8/6/2019 Gwapo Report

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BY: PHILIP GARCIA SANTIAGO

EC 424- Computer System


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CAPTURE, STORAGE, PROCESSING ANDREDISPLAY Computers have different ways of encoding, storage, processing and

redisplay.

Most printer and display equipment, whatever its style of input, doesoperate by presenting a two dimensional pixel array for the eye to

view.

Pixel- is the smallest addressable screen element in raster

graphics; it is the smallest unit of picture that can be controlled.

Although some early graphics display terminals worked by strokinglines into the screen in a programmed sequence, these vector displays

have been completely displaced by the bitmap raster (television-like)types, which are cheaper to manufacture and deal much more easilywith colour images as well as line diagrams.


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THE CATHODE RAY TUBE The CRT (Cathode RayTube), remains the core of most desktop

terminals, despite its size and weight.

an electron tube, or evacuated glass container, having at one end acathode, or negative electrode, and a device called an electron gun thatprojects a beam of electrons against a luminescent screen at theopposite end of the tube. A bright spot of light appears wherever theelectrons strike the screen.

Electrons are emitted from a heated cathode in the electron gun. Aseries of grids having a positive potential with respect to the cathodeaccelerate the electrons as they pass. The electrons next pass through aseries of doughnut-shaped anodes that focus the stream of electrons sothat they strike the luminescent screen as a fine point. Between theelectron gun and the screen are either two sets of electric deflecting

plates or two sets of magnetic deflecting coils. Electric deflecting platesare used in small CRTs.


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Cutaway rendering of a color CRT:

1.) Three Electron guns (for red, green, and blue phosphor dots) 2.) Electron

beams 3.) Focusing coils 4.) Deflection coils 5.)Anode connection 6.) Mask for

separating beams for red, green, and blue part of displayed image

7.) Phosphor layer with red, green, and blue zones 8.) Close-up of the

phosphor-coated inner side of the screen


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THE CATHODE RAY TUBE

In CRTs containing electric deflecting plates, a horizontal pair of platescontrols the up-and-down motion of the electron beam, and a vertical paircontrols the left-to-right motion of the beam. In each pair of plates, oneplate has a negative charge of electricity, and the other plate has a positivecharge. If the charges are equal in value, the beam will strike the center ofthe luminescent screen. If the charges are unequal, the electron beam will be

deflected. The amount of deflection depends on the voltage applied to theplates. As the signal applied to the horizontal plates varies, so will the spotof light on the face of the tube, which will move up or down in response tothe changes in voltage. If the voltage of the vertical plates is varied, thebeam of electrons can be made to sweep horizontally across the face of thetube.


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LCDs (Liquid Crystal Displays) have been universally adopted for portable computers, where the extra

cost is offset by the advantages of reduced weight, size and power

consumption.

ALIQUIDCRYSTAL PANEL


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LCDs Liquid Crystal, substance that behaves like both a liquid and a solid. The

molecules in liquid crystals can move past each other relatively easily, muchlike molecules in a liquid. However, all the molecules in a liquid crystaltend to be oriented in the same manner, much like the moleculararrangement in a solid crystal. Liquid crystals retain their dual liquid andsolid nature only over a certain range of temperatures and pressures.

At sufficiently high temperatures or low pressures, the orientational orderrelaxes into random molecular rotations, causing a liquid crystal to becomean ordinary liquid. At sufficiently low temperatures or high pressures,molecules in a liquid crystal cease being able to easily move by each other,and the liquid crystal freezes into an ordinary solid.

The many classes of liquid crystals include nematic, cholesteric, and various

kinds of smectic phases, each characterized by a different spatialarrangement of the molecules. The optical properties of a liquid crystal canoften be manipulated by subjecting the liquid crystal to a magnetic orelectric field that changes the orientation of its molecules.


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LED SCREEN TECHNOLOGY LED Monitor:

LED monitor is the new version ofLCD monitor, which uses LEDs

to illuminate the display. Now only Samsung andLG

aremanufacturing LED Monitor in market.

How this works:

LED is a diode that emits light. It works like LCD but its backlight is

different.

Technology behind it:

LED monitor use LED backlight replacing the standard

cold cathode fluorescent lamps which was used in LCD monitor. Its

a new version of LCD by replacing backlight.

Why it is better:

It is better because it needs less electricity than LCD. It is also

better than plasma. LED monitor is thin than LCD and Plasma

monitor. LED monitors are eco friendly too.


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A video card, video adapter, graphics accelerator card, display adapter,

or graphics card is an expansion card whose function is to generateoutput images to a display. Many video cards offer added functions, suchas accelerated rendering of 3D scenes and 2D graphics, video capture, TV-tuner adapter, MPEG-2/MPEG-4 decoding, FireWire, light pen, TVoutput, or the ability to connect multiple monitors (multi-monitor). Othermodern high performance video cards are used for more graphically

demanding purposes, such as PC games.co-processing greatly benefits the overall system performance because it

reduces data transfer delays across the buses and relieves the CPU ofroutine low-level tasks. The ISA bus bottleneck has also been bypassed,first by the faster PCI bus, and more recently the AGP slot, which cantransfer data between main memory and the graphics card at 266

Mbyte/s.Graphics accelerators come in a wide variety of forms and capabilities. In

general there are two markets: commercial machines running Windowsand domestic machines running games.

With the change from digital to analogue signalling, the socketconnecting monitors to the graphics adapter card was changed from the

older DB-9 to the high density DB-15.


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Video Graphics Array (VGA) (DB-15)

VGA connectors and cables carry analog component RGBHV (red, green,

blue, horizontal sync, vertical sync) video signals, and VESA Display Data

Channel (VESA DDC) data. In the original version of DE-15 pinout, one pinwas keyed and 4 pins carried Monitor ID bits which were rarely used;

VESA DDC redefined some of these pins and replaced the key pin with

+5 V DC power supply.

Some problems of this standard are electrical noise, image distortion andsampling error evaluating pixels.

Digital Visual Interface (DVI) Digital-based standard designed for displays such as flat-panel displays

(LCDs, plasma screens, wide high-definition television displays) and video

projectors. In some rare cases high end CRT monitors also use DVI. It

avoids image distortion and electrical noise, corresponding each pixel from

the computer to a display pixel, using its native resolution. It is worth tonote that most manufacturers include DVI-I connector, allowing (via simple

adapter) standard RGB signal output to an old CRT orLCD monitor withVGA input.


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Computer display standards or display modes have been used in the

history of the personal computer. They are often a combinationof display resolution (specified as the width and heightin pixels), color depth (measured in bits), and refresh rate (expressedin hertz). Associated with the screen resolution and refresh rate is adisplay adapter. Earlier display adapters were simple frame-buffers,but later display standards also specified a more extensive set ofdisplay functions and software controlled interface.


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The drum is first sprayed with negative electrons which will only escape leak away if the surface is exposed to bright light. The laser diodesource is modulated (turned on and off) by a signal derived from the bitimage of the page to be printed, which has already been built in the localmemory. The black ink powder is fed onto the main drum from the tonerhopper using a smaller drum rotating at twice the speed. This drum has a

magnet inside which attracts the toner dust, and a magnetized bladehelps to distribute it evenly over the surface. As the spreader drumrotates towards the main drum, the toner particles are attracted byelectrostatic force onto the main drum, but only where the laser beam hasnot discharged. There is no direct contact between the two drums. Thetoner particles are then contact transferred onto the paper, which is

heated to fuse the toner permanently into the surface of the paper.


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