Well, today I'll talk about the cathode ray tube. The cathode ray tube (CRT) is the "heart" of the CRO, providing a view of the waveform of an input signal. A CRT contains four basic parts:
- - An electron gun to produce an electron beam;
- Elements of focus and acceleration to produce a well defined beam of electrons;
- Plates horizontal and vertical deflection for controlling the path of the electron beam;
- A glass casing with vacuum fluorescent display, which glows visibly when struck by the electron beam.
Consider first the basic operation of the device. A cathode containing an oxide layer is heated indirectly by a filament, releasing a beam of electrons from the cathode surface. A control grid provides a control of the number of electrons passing into the tube. A voltage on the control grid determines how many electrons liberated by heating are allowed to continue the movement toward the face of the tube. After the electrons pass the control grid, they are focused into a narrow beam and accelerated to a higher speed through the focusing and accelerating anodes. The parties discussed so far include the electron gun of the CRT.
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