Monitor (computer), in computer science, device connected to a computer that displays information on a screen. Modern computer monitors can display a wide variety of information, including text, icons (pictures representing commands), photographs, computer rendered graphics, video, and animation.
Most computer monitors use a cathode-ray tube (CRT) as the display device. A CRT is a glass tube that is narrow at one end and opens to a flat screen at the other end. The CRTs used for monitors have rectangular screens, but other types of CRTs may have circular or square screens. The narrow end of the CRT contains a single electron gun for a monochrome, or single-color monitor, and three electron guns for a color monitor--one electron gun for each of the three primary colors: red, green, and yellow. The display screen is covered with tiny phosphor dots that emit light when struck by electrons from an electron gun.
Monochrome monitors have only one type of phosphor dot while color monitors have three types of phosphor dots, each emitting either red, green, or blue light. One red, one green, and one blue phosphor dot are grouped together into a single unit called a picture element, or pixel. A pixel is the smallest unit that can be displayed on the screen. Pixels are arranged together in rows and columns and are small enough that they appear connected and continuous to the eye.
Electronic circuitry within the monitor controls an electromagnet that scans and focuses electron beams onto the display screen, illuminating the pixels. Image intensity is controlled by the number of electrons that hit a particular pixel. The more electrons that hit a pixel, the more light the pixel emits. The pixels, illuminated by each pass of the beams, create images on the screen. Variety of color and shading...