Connection to Video Card

• A dot-pitch of .28 mm or smaller is good. That's a a bit less than 1/3 of a millimeter.
• Display device, either CRT, LCD, or plasma, plugs into the computer's video port. The video may be integrated into the system board, or it may be on a video card that plugs into an expansion slot on the system board.
• RGB (Red, Green, Blue) separation produces better image than composite video.
• Component video (which is different than composite video) uses 3 RCA cables. RGB information is split into a luminance signal and 2 “color-difference” signals called “chrominance signals,” Pb and Pr.
• S-video often uses a 7-pin mini-DIN connector. It's similar to a Component Video connector but combines the Pb and Pr signals into a single “chrominance” signal. A 4-pin male S-video mini-DIN connector may fit into the 7-pin mini-DIN female jack. The converse is not true: no 7-pin plugs plug into any 4-pin jacks.
• Composite video: chrominance and luminance are combined. Uses only one RCA cable, usually it's yellow.
• Digital audio, called S/PDIF, also uses an RCA jack. Analog audio uses 1/8 inch stereo plugs.
• HDMI has both audio and video signals on the same connector, and both audio and video go through the same cable. Used for HDTV, which uses a digital signal. http://electronics.howstuffworks.com/hdmi2.htm
• Early HDTV relied on DVI connectors. DVI and HDMI (High Definition Multimedia Interface) both use the TMDS (Transmission minimized differential signaling) protocol. You can use an adapter to connect an HDMI cable to a DVI port. See page 57 for more video port descriptions.
• DVI connectors and cables that have a digital signal, or a combination of analog and digital signals, may be single link or dual link. Dual link adds more wires and more connector pins, and can be used to send a signal with greater resolution from the video port on the computer to the display device.
• HDMI extends the advances of DVI. Hi Def Multimedia Interface. Again, HDMI transfers the video and audio signal. DVI only carries the video signal.
• HDMI connector is distinctly different-looking from a VGA connector or DVI connector. It's flat and looks much like an SATA port or connector. With a DVI to HDMI adapter you can plug an HDMI display into a DVI port on a video card.
• HDCP is Copy Protection scheme used for video. Do not confuse with HDMI, which is a signal transmission method.
• A DVI signal is electrically compatible with an HDMI video signal; no signal conversion needs to take place when an adapter is used, and consequently no loss in video quality occurs.[94] As such HDMI is backward compatible with Digital Visual Interface, digital video (DVI-D or DVI-I, but not DVI-A) as used on modern computer monitors and graphics cards. This means that a DVI-D source can drive an HDMI monitor, or vice versa, by means of a suitable adapter or cable. However, the audio and remote-control features of HDMI will not be available.[94] Additionally, not all devices with DVI input support High-bandwidth Digital Content Protection (HDCP). Without such support by the device, an HDCP-enabled signal source will suppress output and so prevent the device from receiving HDCP-protected content.

Video Cards

• Video cards plug into expansion slot.
• Most recent type of slot used for video is PCI express (PCIe). Older video cards plug into AGP (Accelerated Graphics Port) slot. See the section on busses and expansion cards, which explains the types of PCIe slots.

LCD Video

• LCD stands for Liquid Crystal Display. Most are transistors, some are diodes.
• LCD's are active matrix or passive matrix.
• Passive matrix: simple conductive grid. Elegant design but not as fast a response time for each pixel as an active matrix, or as sharp an image (adjacent pixels are affected).
• Active matrix uses a grid of many transistors (along with capacitors) or diodes. It is usually a TFT-LCD, a Thin Film Transistor Liquid Crystal Display. It's a grid of transistors and diodes. LCD does not necessarily mean liquid crystal diode; it usually means Liquid Crystal Display. A transistor is different than a diode and active matrix displays usually use transistors rather than diodes. Although you could have an active matrix display made up of diodes.
• Backlight is for the grid is either fluorescent or LED. Always on. To get intensity, the LCD's filter it.
• Unlike an LED backlight, a CCFL (Cold Cathode Fluorescent Lamp) backlight needs ac power, and thus an “inverter” to convert the dc power to ac.
• It may seem odd that you would start with AC (120 volts 60 hz), convert to DC, then convert back to AC again, but there is a reason. Here is the explanation.
• In short, it's because you can use a smaller transformer. You can adjust the light output more easily. The ac voltage obtained at the output of the inverter is maybe about 1000 volts, and at a much higher frequency than the 60 hz frequency of home and business electric power. This enables a smaller transformer to be used.
• It is also because adjustment of light output is done on the dc side of the inverter, where it can be done most easily.
• LC: Liquid Crystal. Liquid Crystal state is a state between solid and liquid. Soap goop is an example of something in a LC state. Molecules move as in a liquid, but they are oriented relative to each other, and thus have ordered structure like a solid crystal.
• Due to the birefringence of the LC, it can rotate the plane of polarize light. There are 2 polarized plates with polarization at 90degrees to each other (so that no light passes through) and matrix of LC's between the 2 plates. With no juice to the LC, it is "twisted," and thus allows light to pass through the 3 units. Giving the LC juice un-twists the criystal, and reduces the amount of light going through the 3 units. Order: diffuser, polarizer, LC, seocnd polarized plate, red green or blue filter.

Plasma Video

• Plasma video has gas in a glass chamber, like fluorescents do. Each chamber has either a red, green, or blue phosphor. Intensity is controlled by frequency and rectangularty of the electric wave refreshing the voltage (turning the juice on and off). Better contrast ratio than LCD's. But it uses more energy. Energy level depends on brightness. LCD uses about the same amount of juice regardless of brightness. Functions similarly to a CRT, except there are lots of separate chambers each with their own “electron beam"), instead of one chamber with lots of phosphor dots and 1 to 3 moving electron beams. Plasma screens, like CRT's, are susceptible to burn-in
• Projection video uses CRT or CRT's, or LCD image to produce image, and lens.
• You can have front projection or rear projection. Image can be produced 2 ways, reflective and transmissive. Light souce arranges so that light bounces off image, or passes thru image.
• CRT method, you can have a single CRT with red, green and blue phosphors; or one black-and-white CRT and a spinning color wheel that adds the color; or three CRTs, one each for red, green and blue.
• LCD methods: One transmissive method, LCD device creates a greyscale image. To add color, most projectors use a series of mirrors that split the light source into red, green and blue beams. Each beam passes through a separate LCD, and a lens collects the three beams and projects the image on the screen.
• Reflective methods: DLP projector uses a digital micromirror device (DMD).
• LCoS: LCoS is simultaneously reflective and transmissive, and it's like a combination of DLP and LCD technology. In an LCoS set, light passes through a liquid crystal layer, then bounces off a reflective surface, then passes back through the liquid crystal to control intensity. Usually separate LC's for R, B, and G.
• Aspect ratios : 4:3, 16:9.
• Aspect ratios:

• See page 56. QXGA, quad XGA, double XGA. 2048x1536.
• Troubleshooting. Video before the POST single beep – video hardware is good. Problem starts after beep – software problem. Driver corruption or configuration errors.