The Computer Revolution/Peripherals/Monitors

Monitors

CRT

CRT also known as cathode ray tube monitors were the most widely used computer monitors until the release of LCD monitors. CRT monitors are inexpensive and easy to maintain, however CRT monitors develop glare from the surroundings and can cause reflection resulting in a poor quality for viewing. CRT monitors also are quite larger in comparison to LCD monitors . The reason for the size of the CRT monitors is due to the same technology employed in some televisions screens. The Cathode ray projects a series of electrons onto a screen to ultimately produce an image, however the process of electrons to an image is much more tedious than a simple conversion.

History of the CRT

A German scientist Karl Ferdinand Braun in 1897 invented the first cathode ray tube. Braun introduced a CRT with a fluorescent screen, known as the cathode ray oscilloscope - an oscilloscope is an electronic display device containing a cathode ray tube (CRT), used to produce visible patterns that are the graphical representations of electrical signals. The screen would emit a visible light when struck by a beam of electrons. A Russian scientist Boris Rosing, in 1907, used a CRT in the receiver of a television system. Rosing also transmitted crude geometrical patterns onto the television screen and was the first inventor to do so using a CRT. The first practical signal generating tubes were invented by Vladimir K. Zworykin and Philo T. Farnsworth.

Other Advantages of the CRT Monitors

• Accurate color- CRTs provide richer color in a fuller variety than most LCDs
• Response time- may respond more quickly than some LCDs in regards to videos and action games
• Viewing angle- CRT provides brightness and color from a variety of different viewing angles
• Multiple resolutions
• Purchase price- CRTs are less expensive than LCDs

Disadvantages of the CRT Monitor

• Very heavy and large
• Uses large amounts of energy
• Generates excess heat

LCD

LCD or liquid crystal display screens are the newest and sharpest screens. Even though the use of LCD screens have been around for a long time, the technology has only been recently incorporated into the use of both televisions and computer monitors. The LCD screen uses rare characteristics that make it much more appealing than conventional CRT monitors. One of the key characteristics of LCD screens are the size advantage compared to a conventional CRT screen, a LCD screen does not employ the use of a cathode ray. But instead layers of filters and glass which polarize light and project onto liquid crystals which reveal sharp quality and excellent detail of the picture. Another interesting aspect of LCD screens is that there is almost no reflection of light from the surroundings into the screen.

Other Advantages of the LCD Monitors

• Brightness- the LCD monitor has a brightness of 250 to 300 nits
• No flicker- there is no flicker on a LCD, because it has a constant source of light over the whole screen
• Power consumption- consumes less power than the CRT, approximately one-third
• Ergonomics- the dimensions and the weight of the LCD permit it to consume less space. Example: mounting it on a wall
• Low emissions- LCDs cause no electromagnetic interference

Disadvantages of the LCD Monitor

• Blurry images outside native resolution
• Motion blur on fast moving images
• Some models have reduced color clarity

Electronic Paper

Amazon Kindle 4

Have you seen the Amazon Kindle or Sony E-Reader? If you have, you’ve noticed that the screen looks almost exactly like a printed sheet of paper. That’s because these devices use electronic paper (e-paper) for their display. An electronic paper display uses a technology called electrophoretics that was developed by E Ink Corporation. The technology uses tiny charged white and black ink particles to simulate the look of paper. An applied voltage pulls either the white or black beads to the top of the screen, while the opposite beads fall to the bottom, thus giving the contrasting look of the words versus background on the screen. The technology requires much less power than other flat panel display technologies because there is no back-light needed and no power required to maintain the display, only to change the display. Devices using this technology are much easier to read in direct sunlight as well.

OLEDs

Organic light emitting diode (OLED) a type of flat-panel display that may one day replace LCD technology. OLED displays use layers of organic material which emits light when electric current is applied. OLEDs are more energy efficient than LCDs because they don’t use backlighting which also lengthens the battery life of portable devices. Other advantages of OLEDs is that they are thinner than LCDs and have a wider viewing angle, so the display is visible from all angles. Another advantage of OLEDs is that they support new technologies such as flexible OLED (FOLED) in which the display is built on a flexible surface, allowing is to roll up when the device is not in use, and transparent OLED (TOLED) where the part of the display that doesn’t have an image is totally transparent. This could open up possibilities such as the use of displays on windows, auto windshields, and other transparent items.

Flat Panel Display

Digital Vs Analog

Analog and digital signals rely on two very different ways of translation. Analog is initially a digital signal that becomes translated by a graphics card into an analog signal which is than used for the display of the monitor. However the problem in this process is that quality and definition becomes “lost” in the translation from digital to analog, resulting in less sharpness and depth. Now a digital signal when properly connected to a DVI or digital video interface allows the digital signal to be directed right to monitor with no translation.DVI provides high-speed digital interface through Transition Minimized Differential Signaling (TMDS). A transmitter on the video adapter transfers digital data to a receiver in the monitor. TMDS accepts the signal from the video adapter, determines the resolution and refresh rate that the monitor is using, and spreads the signal out over the available bandwidth to optimize the data transfer from computer to monitor. This results in a higher quality picture that appears more crisp and clean.

DVI-VGA Adapter