The phosphorous converts the electrical energy into light energy. The internal surface of the faceplate is coated with the phosphor. The face plate of the CRT is made up of entirely fibre optics which has special characteristics. The front of the CRT is called the face plate. The electron beam entering into the deflection plates will accelerate only in the one direction, and hence electrons will not move in the other directions. The deflection plate produces the uniform electrostatic field only in the one direction.
They are the Electrostatic Focussing Beam and the Electromagnetic Focusing. The pre-accelerating and accelerating anode are connected to the positive high voltage of about 1500V and the focusing anode are connected to the lower voltage of about 500V.There are two methods of focusing the electron beam. After exiting the focusing anode, the beams passes through the vertical and horizontal deflecting plates. The accelerating and focusing electrodes are cylindrical in shape which has a small opening in the centre of each electrode.
The electron which is emitted from the electron gun and passes through the control grid have high positive potential which is applied across the pre-accelerating and accelerating anodes. This control grid is made up of nickel material with a centrally located hole which is coaxial with the CRT axis. The electron passes through the electron in the small grid. The cathode is cylindrical in shape, and at the end of it, the layer of strontium and barium oxide is deposited which emit the high emission of electrons at the end of the tube. The electrons are emitted from the highly emitted cathode. The electron gun has a heater, cathode, grid, pre-accelerating anode, focusing anode and accelerating anode. The electron gun is the source of the electron beams. The detail explanation of their parts is explained below. The electron gun emits the electron beam, and through deflecting plates, it is strikes on the phosphorous screen. The Electrons Gun Assembly, Deflection Plate Assembly, Fluorescent Screen, Glass Envelope, Base are the important parts of the CRT. The working parts of a CRT are enclosed in a vacuum glass envelope so that the emitted electron can easily move freely from one end of the tube to the other. The horizontal and vertical movement of the electron are independent of each other, and hence the electron beam positioned anywhere on the screen. The one pair of plate moves the beam upward and the second pair of plate moves the beam from one side to another. These plates deflected the beams when the voltage applied across it. This high-velocity electron beam when strikes on the fluorescent screen creates luminous spotĪfter exiting from the electron gun, the beam passes through the pairs of electrostatic deflection plate. The electron guns generate sharply focused electrons which are accelerated at high voltage. The working of CRT depends on the movement of electrons beams.
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