What is the full form of CRT?

Introduction

Cathode Ray Tube (CRT) is a vacuum glass tube consists of multiple electron guns. They create images a beam of electrons, allowing to project the output on the phosphorescent screen. Today we see flat-screen televisions and monitors but we must remember about heavy television and computer monitors. They were big in size and heavy. That television was worked on (CRT) cathode ray tube technology.

The physicist “Johann Hittorf '' discovered the Cathode rays in Crooks tube in 1869. Crooks tubes are vacuum tubes having two electrodes that are kept at high potential difference which discharge cathode rays.

• In 1897, “Physicist J.J. Thomson” discovered electrons while working on cathode rays.

• The first version of the Cathode ray tube was discovered by “Physicist Ferdinand Braun” known as the “Braun Tube”.

Introduction to CRT

The CRT stands for “Cathode Ray Tube”. CRT is a vacuum glass tube used to create images by a beam of electrons on the phosphorescent screen. Once the beam of the electron is projected on the screen, the image is displayed. Cathode ray tube has various components electron gun, electrode, focusing system and deflection unit, and a fluorescent screen.

• Electron Gun − Electron guns produce an electron beam which emits electrons. It has different parts: heater, cathode, control grid, and accelerating anode. The control grid controls the electron beam.

• Focusing System − It created a clean image by focusing the system on a narrow beam at a point.

• Deflection Unit − The deflection unit is formed by two parallel plates vertical and horizontal deflection plates. The electron beam coming from the anode tries to spread; these beams collide with fluorescent tubes and collide the beam path.

• Fluorescent Screen − It is a phosphorus-coated or zinc-sulphide-coated plate. When an electron beam strikes the screen it is fluorescent and displays the image.

How CRTs Works?

The cathode ray tube is a vacuum glass tube in which an electron gun emits an electron beam which travels through various parts of the tube and generates the image on the screen. Let's see in detail how it works.

• The electron gun first emits the electron beam from a highly emitted cathode tube by heating it.

• The beam passes through the control grid, which has a small hole the beam passes through the grid in a straight line.

• The negative voltage applied to the control grid controls the intensity of the beam.

• The beam then passes through positively charged anodes which increase the velocity of the beam and keep it focussed.

• The focussed beam then passed through two deflection plates X and Y which are horizontal and vertical deflecting plates.

• The beam is focused on that plate moving so that it deflects on-screen on the waveform.

• Then the deflected beam strikes the screen with high velocity.

• The screen coated with phosphor converts the electrical energy into light energy.

• The beam that strikes the screen moves with a high velocity and generates a bright spot on the screen. The beam passes at high speed and it appears like a wave, which generates an image.

Advantages and Disadvantages of CRT

There are some advantages as well as disadvantages of cathode ray tubes.

Advantages

• The cathode ray tube is used in display screens in radar.

• CRTs are used for the manufacturing of television screens and video games.

• Cathode ray tubes are also used in the manufacturing of computer monitors.

• They are also used in oscilloscopes. The oscilloscope is used in laboratories to study waveform signals, voltages, and current measurements.

• The cathode ray tube was also used to generate luminescence on chemical screens.

• In Oscilloscope, the tube is used for troubleshooting.

Disadvantages

There is some health risk associated with it.

• The cathode ray tube emits some amount of ionized radiation which causes health issues.

• The cathode rays tubes have a low refresh rate, which is 60 Hz or less than it, which causes winking of the eyes. It varies from person to person.

• The use of cathode ray tubes increased significantly in the past few years due to television and monitor manufacturing. It is difficult to dispose of these tubes which are causing environmental hazards.

• The high frequencies are used for operating cathode ray tubes which is causing noise pollution for human ears.

• They are formed from glass vacuum tubes which should be handled with care as they can cause injuries if shattered accidentally.

Conclusion

Cathode rays are a key discovery in science and technology. It is prepared using a vacuum glass tube. There is an electron gun assembly which passes an electron beam which passes through the cathode and anodes and strikes on a phosphor screen which creates a luminance. There are two types of CRT: monochrome CRT and multicolour CRT which is black and white multicoloured respectively. The multicolour light produced is red, green and blue colour. It is used for various purposes in science and technology like in radars. Oscilloscopes, televisions, computer monitors, etc.

FAQs

Q1. Which Scientist first used the cathode ray tube in television?

Ans: The Russian scientist Boris Rosing first used the cathode ray tube in television. He passed the video signal through a cathode ray tube and got a geometrical shape on the screen.

Q2. In which year the first commercial manufacturing of television started?

Ans: In 1934 a German company Telefunken started the manufacturing of the first commercial television using cathode ray tube technology. Now the CRT system is replaced by a more advanced Liquid crystal display and light-emitting diode technology which reduces the size of televisions.

Q3. How many types of CRT are known?

Ans: There are two types of cathode ray tubes; cathode display tube (CDT) and cathode picture tube (CPT). The cathode display tubes are used in computer monitors and the cathode picture tube is used in the manufacturing of televisions.