Saturday, March 22, 2008


Monitor is also called as ‘VDU’ Visual Display Unit. Monitors & TV set’s use ‘CRT’ Cathode Ray Tube technology initially. In the present environment a newly developed technology has changed the entire VDU’s drastically referred as ‘TFT’ Thin-Film Transistor known as LCD. In today’s world the monitor is not “Just a Display”, by HD (High Definition) a high quality video content is available today. With the High quality rendering Video and High end Graphics and Games there is an improvisation in display.

Older: In previous technology CRT is used in display stands for picture tube. In CRT there is a glass envelop consists an electron gun and a phosphor-coated screen. When a computer sends display signals to a monitor these (signals) are converted in to electrons, beamed on to the phosphor-coated screen by electron gun creating an image on the screen.

Newer: In present technology TFT technology is used in LCD displays. The main advantage of TFT is the presence of the tiny transistors that make each pixel on the screen. The power consumption is low due to the transistors being diminutive in nature. LCD is also referred as Flat screen or TFT which consists of a liquid-crystal material which is sandwiched between two sheets of glass. When the current passes the molecules inside change their alignment causes light emission on some portions and blocked on some other finally creates an image.

HD (High Definition): HD refers to a video system or stream of higher definition than the standard (SD).The resolution of a HD TV or Monitor is 1080 or 720 horizontal lines, whereas the resolution a digital television (DTV) is 486 lines.

Advantage of TFT (LCD) over CRT: TFT’s are light weight, occupies less space, radiation emission and so on. Native Resolution is present in LCD and it is absent in CRT.

Disadvantage: Response time taken is large which causes blurriness while watching action packed scenes. Viewing angle shows the difference in watching CRT & LCD.

Different aspects between CRT & LCD

Screen Size: The screen size of CRT monitor is measured diagonally across opposite corners of the screen in inches. In CRT monitor the display area is smaller because it includes screen frame where as in LCD it is measured excluding the borders.

Aspect ratio: The Aspect ratio is nothing but the ratio of width to height. In CRT & in normal TV sets it is 4:3 , where as in LCD and present technology used in TV’s there are two types of display namely Conventional & Wide screen. The present aspect ratios are 4:3 & 16:10 (used in HDTV).

Due to this Aspect ratio we may sometimes see the Black Bands at the top and Bottom.

Resolution: Resolution is the number of pixels gets active during display in the monitor. The higher the resolution gets better picture clarity. It is measured as Width * Height.

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