The oscilloscope is a type of electronic measuring instruments which can achieve a variety of object measurement. Then with what kind of structural components enable the general oscilloscope to complete the entire measurement process? The following section describes the components of the general oscilloscope.

The display circuit includes the oscillograph tube and its control circuit. Oscillograph tube is a special kind of tube and also an important part of the oscilloscope. The oscillograph tube consists of three parts: electronic gun, deflection system and phosphor screen.

Electronic gun

The electronic gun is used to generate and form a high-speed, bunch of electronic flow to bombard and light the phosphor screen. It mainly consists of filament F, cathode K, gate G, first anode A1, and second anode A2. In addition to the filament, the rest of the electrode structure are metal cylinders, and their axis are maintained on the same axis.

After the cathode is heated, electrons can be emitted in the axial direction; the control electrode is negative potential relative to the cathode, changing the potential can change the number of electrons through the control of the tiny hole, that is, control the brightness of the spot on the screen.

In order to improve the brightness of the screen on the screen without reducing the sensitivity of the electron beam deflection. In the modern oscilloscope, a post-acceleration electrode A3 is also added between the deflection system and the phosphor screen.

Deflection system

Oscillograph tube deflection system are mostly electrostatic deflection type, which consists of two pairs of vertical parallel metal plate composition, respectively, known as the horizontal deflection plate and vertical deflection plate.

Respectively, they control the electron beam in the horizontal and vertical movement. When the electrons move between the deflection plates, if there is no voltage applied to the deflection plate, there is no electric field between the deflection plates, and the electrons entering the deflection yoke from the second anode will move axially to the center of the screen.

If there is a voltage on the deflection plate, there is an electric field between the deflection plates, and the electrons entering the deflection yoke are directed to the designated position of the screen by the deflection of the electric field.

If the two deflection plates are parallel to each other and their potential difference is equal to zero, the electron beam having the velocity υ through the deflection plate space will move in the original direction (in the axial direction) and hit the coordinate origin of the phosphor screen .

Fluorescent screen oscilloscope

The phosphor screen is located at the end of the oscillograph tube, and its function is to display the deflected electron beam for observation. The inner wall of the phosphor screen is coated with a layer of luminescent material, so that the fluorescent screen by high-speed electron impact on the location of the fluorescence.

The brightness of the spot is determined by the number, density and speed of the electron beam. When the voltage of the control electrode is changed, the number of electrons in the electron beam will change and the light spot brightness will change.

When using the oscilloscope, it is not advisable to place a very bright spot on the screen of the oscilloscope. Otherwise, the fluorescent substance will burn out due to long-term electron impact and lose its ability to emit light.

The above is a brief introduction to the three components of the general oscilloscope, we should line up these three parts to understand, combining with the actual operation we can clearly know how these three parts works on their field.

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