MGMT 1050 Lecture Notes - Lecture 2: Passive Matrix Addressing
MGMT 1050 Tutorial 2 Notes – CRT Display Technology
Introduction
• In an active matrix display, the display panel contains one transistor for each cell in the
matrix.
• This guarantees that each cell will receive a strong charge, but is also expensive and
difficult to manufacture.
• Remember that even one imperfect cell will be apparent to the viewer!
• A less expensive way provides a single transistor for each row and column of the matrix
and activates each cell, one at a time, repetitively, using a scan pattern.
• This type of panel is known as a passive matrix display.
• The charge is applied for less time and is therefore lower.
• The result is a dimmer picture. Most modern LCD displays use the active matrix
approach.
• LCD panels have the advantage of bright images, no flicker, low power consumption,
and thinness, so they are ideal for laptop computers.
• They are also used in most desktop displays.
• Because they are essentially flat, they can be placed anywhere.
• The same technology is also used for large-screen computer projectors.
• With CRT technology, the image is produced on the face of a cathode ray tube (CRT),
using a methodology similar to that used for older television receivers.
• A diagram of a color cathode ray tube is shown
• Three electron guns within the tube shoot beams of electrons from the back of the tube.
• There is a gun for each of the primary colors, red, blue, and green.
• A high voltage applied to the inside of the face of the tube attracts the beams to the
face.
• The face of the tube is painted with tiny dots or thin strips of phosphors, which glow
when struck by electrons.
• There are phosphors that glow red, blue, and green.
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