Unformatted text preview: with
larger screens are preferred. However, the larger the screen the costlier is the monitor.
2. Resolution. Resolution refers to the number of points to which electron beam can be
directed (pixels) on the screen. As the pixels are arranged in scan lines, the resolution of a
monitor depends on its total number of scan lines and total number of pixels per scan line
(note that each scan line has same number of pixels). The total number of scan lines is
called a monitor's vertical resolution and the total number of pixels per scan line is called
its horizontal resolution. The overall resolution of a monitor is expressed as a multiple of
its horizontal and vertical resolutions. A low-resolution monitor has a resolution of about
320 x 200. Today, most monitors have a resolution of about 800 * 600. High-end
monitors can have resolutions of 1024 x 768, 1280 x 1024 or even more. The higher the
resolution of a monitor, the clearer will be its displayed images. Very high-resolution
monitors project extremely clear images that look almost like photographs.
3. Refresh Rate. We saw that when a pixel on the phosphor-coated screen is hit by the
electron beam, it glows only for a short time (few microseconds) and then fades away.
Hence to make a displayed image appear flicker-free, it should be drawn again and again.
The number of times it is to be drawn depends upon the persistence of human vision and
persistence time of the phosphor used. Normally an image has to be redrawn 30 to 60
times a second to make it appear flicker-free. We saw that the electron beam scans the
entire screen for drawing images on the screen. Hence to make the displayed contents
appear flicker-free, the electron beam should scan the entire screen 30 to 60 times a
second. The actual number of times that the electron beam scans the entire screen per
second is called the refresh rate of the monitor. The higher the refresh rate, the better will be the display quality of a monitor because it will be less strenuous for the eyes to
continuously view the scre...
View Full Document
This document was uploaded on 04/07/2014.
- Spring '14