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

Extensiones de Documento y Formatos de Documento

Accionado por:

SearchCompliance

  • compliance audit

    A compliance audit is a comprehensive review of an organization's adherence to regulatory guidelines.

  • regulatory compliance

    Regulatory compliance is an organization's adherence to laws, regulations, guidelines and specifications relevant to its business...

  • Whistleblower Protection Act

    The Whistleblower Protection Act of 1989 is a law that protects federal government employees in the United States from ...

SearchSecurity

  • reverse brute-force attack

    A reverse brute-force attack is a type of brute-force attack in which an attacker uses a common password against multiple ...

  • orphan account

    An orphan account, also referred to as an orphaned account, is a user account that can provide access to corporate systems, ...

  • voice squatting (skill squatting)

    Voice squatting is an attack vector for voice user interfaces (VUIs) that exploits homonyms (words that sound the same but are ...

SearchHealthIT

SearchDisasterRecovery

  • business continuity policy

    Business continuity policy is the set of standards and guidelines an organization enforces to ensure resilience and proper risk ...

  • business continuity and disaster recovery (BCDR)

    Business continuity and disaster recovery (BCDR) are closely related practices that describe an organization's preparation for ...

  • warm site

    A warm site is a type of facility an organization uses to recover its technology infrastructure when its primary data center goes...

SearchStorage

  • RAM (Random Access Memory)

    RAM (Random Access Memory) is the hardware in a computing device where the operating system (OS), application programs and data ...

  • primary storage (main storage)

    Primary storage is the collective methods and technologies used to capture and retain digital information that is in active use ...

  • cache memory

    Cache memory, also called CPU memory, is high-speed static random access memory (SRAM) that a computer microprocessor can access ...

Close