Browse Definitions :
Definition

cathode ray tube (CRT)

A cathode ray tube (CRT) is a specialized vacuumtube in which images are produced when an electron beam strikes aphosphorescent surface. Most desktop computer displays make useof CRTs. The CRT in a computer display is similar to the"picture tube" in a television receiver.

A cathode ray tube consists of several basiccomponents, as illustrated below. The electron gun generates anarrow beam of electrons. The anodes accelerate the electrons.Deflecting coils produce an extremely low frequency electromagnetic field that allowsfor constant adjustment of the direction of the electron beam.There are two sets of deflecting coils: horizontal and vertical.(In the illustration, only one set of coils is shown forsimplicity.) The intensity of the beam can be varied. Theelectron beam produces a tiny, bright visible spot when itstrikes the phosphor-coated screen.

To produce an image on the screen, complexsignals are applied to the deflecting coils, and also to theapparatus that controls the intensity of the electron beam. Thiscauses the spot to race across the screen from right to left, andfrom top to bottom, in a sequence of horizontal lines called theraster. As viewed from the front of the CRT, the spot moves in apattern similar to the way your eyes move when you read asingle-column page of text. But the scanning takes place at sucha rapid rate that your eye sees a constant image over the entirescreen.

The illustration shows only one electron gun.This is typical of a monochrome, or single-color, CRT. However,virtually all CRTs today render color images. These devices havethree electron guns, one for the primary color red, one for theprimary color green, and one for the primary color blue. The CRTthus produces three overlapping images: one in red (R), one ingreen (G), and one in blue (B). This is the so-called RGB colormodel.

In computer systems, there are several display modes, or setsof specifications according to which the CRT operates. The mostcommon specification for CRT displays is known as SVGA (SuperVideo Graphics Array). Notebook computers typically use liquid crystal display.The technology for these displays is much different than that forCRTs.

This was last updated in September 2005

Join the conversation

2 comments

Send me notifications when other members comment.

Please create a username to comment.

Thanks!
Cancel
"Most desktop computer displays make useof CRTs". Last century called. They want their CRT back.
Cancel

-ADS BY GOOGLE

File Extensions and File Formats

Powered by:

SearchCompliance

  • risk management

    Risk management is the process of identifying, assessing and controlling threats to an organization's capital and earnings.

  • compliance as a service (CaaS)

    Compliance as a Service (CaaS) is a cloud service service level agreement (SLA) that specified how a managed service provider (...

  • data protection impact assessment (DPIA)

    A data protection impact assessment (DPIA) is a process designed to help organizations determine how data processing systems, ...

SearchSecurity

  • Port Scan

    A port scan is a series of messages sent by someone attempting to break into a computer to learn which computer network services ...

  • DMZ (networking)

    In computer networks, a DMZ (demilitarized zone), also sometimes known as a perimeter network or a screened subnetwork, is a ...

  • quantum supremacy

    Quantum supremacy is the experimental demonstration of a quantum computer's dominance and advantage over classic computers by ...

SearchHealthIT

SearchDisasterRecovery

  • business continuity plan (BCP)

    A business continuity plan (BCP) is a document that consists of the critical information an organization needs to continue ...

  • disaster recovery team

    A disaster recovery team is a group of individuals focused on planning, implementing, maintaining, auditing and testing an ...

  • cloud insurance

    Cloud insurance is any type of financial or data protection obtained by a cloud service provider. 

SearchStorage

Close