How Computer Display Technologies Work - Part 2

Learn About The Technology Behind Todays LED and LCD Display Devices

Working With Different Types Of Computer Displays and The Various Technologies used to implement them

CRT’s present several significant problems with their use. They’re bad for your eyes! They produce an enormous amount of flicker that resolutions less than 75Hz can strain your eyes very quickly. They’re also very heavy. The screen themselves have enormous amount of led and the electron gun weigh a lot. They are bulky and the lead itself presents health concerns if the case were to become compromised and the led were able to leak out. They also, release electromagnetic radiation. This definitely represents a health concern including the risk of certain cancers. This electromagnetic radiation can even cause laptops and other nearby electronic components to not function properly or even fail altogether. In some instances it’s very probable that a CRT could destroy data on a laptop hard drive that’s powered on nearby. I’ve seen this happen. I had client a few years ago who called complaining that his laptop was going hey wire! Upon inspection I quickly noticed he had CRT monitor positioned directly next to the laptop itself. The data on the hard drive was scrambled and destroyed, and I noticed the monitor releasing a more than usual amount of electro static electricity as well. If a CRT should be dropped, broken, or the screen should crack, they present an immediate health risk from the lead located inside the screen. This also presents an environmental issue as well. And, last but not least, CRT’s act like giant capacitors holding enormous amounts of electricity at high voltages, even when they’re powered off, or unplugged for months! Never open a CRT monitor to inspect it for any reason. There’s enough voltage in them to kill you! You will not be tested on repairing CRT monitors with any Comp TIA exams. You should always dispose of CRT monitors appropriately by taking them to an electronics recycling center. Usually there is a fee to do this. Most fees run around $10 to $15. Don’t throw a CRT in the trash! This is illegal in most any jurisdictions, and you can make a sure bet you will be met with criminal and civil charges. In some cases you could even lose your business and or professional licenses as a result of negligence for doing so. All that being said, if you are still using a CRT monitor, get rid of it ASAP! They’re not worth the risks!

Display resolutions: Screen Resolution is measured in pixels (Picture Elements), by both its horizontal and vertical orientations. If a screen is 800 pixels wide by 600 pixels in height, we can say it has a resolution of 800X600. If you multiply both the horizontal (X) and Vertical (Y) axis together, you define the resolution in “megapixels.” Mega simply means million and in this case it is actually defined as approximately 2 to the 20th power, or 1,048,000 pixels. Why the weird number? We are measuring in powers of 2. Infact computers don’t natively understand the decimal system at all. They only understand one of 2 values, meaning true or false, off or on, or logically a 1 or 0. This is called the binary system. If you want to learn more about how computers read, write and interpret data using the Binary system, be sure to look at our guide to “IP addressing and the Binary system”(IPADDRESSING.HTML) under our computer networking tutorials.

Here are some common resolutions and their names that you will come across when working in the field, as well as be tested on when you take you’re A+ exams:

VGA: Vide Graphics Array. Defined as 640X480 resolution and has a 4:3 aspect ratio (meaning 4 parts to 3 parts). This is also the resolution you will encounter on windows XP operating systems when there is no graphics driver installed on the system, or the operating system has been booted into safemode.

SVGA: Super Video Graphics Array. Has an 800X600 and also has a 4:3 aspect ratio. This is the common resolution you will encounter in a windows vista or windows 7 operating system when no graphics driver has been installed, or when booting into safemode.

XGA: Extended Graphics Array. Has a 1024X768 resolution and also has a 4:3 aspect ratio. This was the standard laptop resolution for many years.

WXGA: Widescreen Extended Graphics Array. Has a 1280X800 resolution and a 16:10 aspect ratio. There is also WXGA (HD) which is usually defined as 1366X768 which has an aspect ratio of 16:9.

SXGA: Super Extended Graphics Array. Has a 1280X1024 resolution and a 5:4 aspect ratio. Not uncommon on some older desktop PC monitors. Many Dell PC’s shipped back in the mid and early 2000’s with monitors of this resolution.

WSXGA+: Widescreen Super Extended Graphics Array Plus. Has a resolution of 1680X1050 and an aspect ratio of 16:10.

WSXGA+ (HD): Same as above accept 1680X945 and a 16:9 aspect ratio.

WUXGA: Widescreen Ultra Extended Graphics Array. 1920X1200 resolution and an aspect ratio of 8:5. This resolution is more common these days among home desktop monitors and some LCD TV’s.

Video Connector Types and Technologies:

VGA: Video Graphics Array. Despite being one the oldest display monitor connections the DB15 connector is still very much in use today. Has male and female connections. It is an analog display technology that uses RGB values to display images. The DB stands for “data bus” and the 15 means 15 fifteen pins. Standard analog video cards generally use a DB15 Female connection. These connectors were used from everything from the old CRT monitors to current day laptops and home desktop monitors. Most laptops have an external DB15 Female connection in order to send your internal video signal to an external monitor.

HDMI: High Definition Multimedia Interface. This is one of the most common video display connections available today. Unlike standard VGA DB15 connections, HDMI carries both audio and video sources in the same connection, and it’s all digital! Their connections are similar looking to that of a USB connector. Most current laptops also have HDMI connections.

DVI: Digital Video Interface or arguably Digital Visual Interface. DVI is a protocol that is able to handle both digital and analog video transmissions. There are several types DVI connections, and yes you will be tested on these for your exams.

Continue To Part 3