Radar Terms used in Engineering
"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",
"N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"

CRT Definitions

Graphic of a Cathode-ray Tube Display
Cathode Ray Tube Cut-away

CRT: Cathode-ray Tube. An electron tube that has an electron gun, a deflection system, and a screen. This tube is used to display visual electronic signals. An electron beam is focused on a luminescent screen than varied in position and intensity to produce a visible pattern.

A Cathode-ray Tube is used as computer monitors, television screens or radar displays. A CRT is assembled into a monitor, which includes several other parts, such as a plastic cabinet, electromagnetic shields, circuit boards, connectors, and cabling. CRT displays are in decline, and are being replaced by Flat screen LCD displays that reduce weight, take up less space, and consume less power. Flat screens handle shock better than CRTs.

CRT Terms

Angle of Deflection. The angle of an electron beam induced by the deflection coils of a CRT. The new position of the electron beam compared original position before the beam passed through deflection plates.

Anode. A positive electrode of a two terminal device, toward which the negative ions are drawn. The first and second Anode in the above graphic form the focus section of the CRT. The anode or anode button on a CRT is the opening near the back end of the display screen, used to accept a compression lead as a connection.

Cathode. In an electron tube the electrode that is the source of current flow.

Cathode Ray Tube. Displays light on a two-dimensional phosphor screen.

CRO. Acronym for Cathode-Ray Oscilloscope.

CRT. Acronym for Cathode-Ray Tube.

CRT Electron Gun. See Electron Gun.

Control Grid. The Control Grid of a CRT is used to control the brightness of the screen, as the Control Grid limits or controls the amount of electronics passing through it hitting the screen. The more electrons allowed to hit the screen, the brighter the output of the CRT.

Decay Time. The time interval during which the stored information decays to a stated fraction of its initial value [Persistence of a storage scope].

Display. The face of the CRT that is used to display information. See Screen.

Deflection Coils. In a cathode-ray tube [CRT], coils used to bend an electron beam a desired amount.

Electron Gun. An electrode of a CRT that is equivalent to the cathode and control grid of conventional tubes. The electron gun produces a highly concentrated stream of electrons.

Diagram of a Cathode-ray Tube Electron-Gun
Cathode Ray Tube Electron-Gun

Electron Beam. A flow of electrons that have been focused by an Electrostatic field into a narrow beam.

Electron Tube. Types of Electron Tubes.

Electrostatic Defection. The method of deflecting an electron beam by passing it between parallel charged plates mounted inside a cathode-ray tube. CRT, Internal View.

Filament. The cathode of a thermionic tube, usually a wire or ribbon, which is heated by current passing through it.

Focusing Anode. An electrode of a CRT that is used to focus the electrons into a tight beam.

Graphic Coating. Manufacturers generally employ significant quantities of lead in the glass used to make color CRTs. Televisions and color computer monitors contain an average of four pounds of lead.

Heater. See Filament.

Horizontal Amplifier. Converts the time-base ramp to a deflection voltage for the Horizontal CRT deflection plates.

Horizontal-Deflection Plates. A pair of parallel electrodes that moves the electron beam from side to side in a CRT.

Luminance. The luminous intensity per unit area on the screen.

Neck. The long narrow portion of the glass tube.

Presistance. The length of time a phosphor dot glows on the tube face of the CRT before disappearing.

Phosphor. A layer of luminescent material that is applied to the internal portion of the screen, the inner face of the CRT.

Pins. Leads on the tube neck for connection and interfacing.

Raster. The predetermined pattern of scanning lines on a CRT.

Ray-Control Electrode. An electrode that controls the position of an electron beam inside a CRT.

Scanning Beam. Text in review.

Screen. The surface of a cathode-ray tube that produces a visible image or pattern.

Vacuum Tube. An electron tube evacuated such that its electrical characteristics are essentially unaffected by the presence of residual gas. Vacuum Tube graphic. CRTs are vacuum tubes, made primarily of glass, which constitute the video display components of televisions, computer monitors, and other electronic devices.

Vertical Amplifier. Determines the bandwidth and gain of the device.

Vertical Deflection Plates. A pair of parallel electrodes in a CRT that moves the electron beam up and down.

Yoke. A set of coils placed around the end of the neck of a CRT to magnetically deflect the electron beam before it hits the back of the CRT screen. The yoke holds the [N-S] vertical deflection coils and the [E-W] horizontal deflection coils. The yoke is more or less the combination of the deflections coils and the mounting bracket placed around the CRT. A Scanning Yoke.

In general CRT screens are obsolete, but it will be years before companies will trade in their expansive oscilloscopes and logic analyzers that use CRT screens. Personal TVs might be traded in for flat panel screens, but businesses are less likely to dispose of expensive gear in order to trade up.

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