Oscillograph is the electron with a kind of very extensive use measures an instrument. It can alternate the telegraphic date with invisible naked eye into the picture that sees so that see, facilitating people studies the metabolic process of all sorts of report appearances. Oscillograph uses stricture, the electron beam that comprises by high speed electron, on the screen range that is made in besmear have fluorescent material, can produce petty spot. Below the action of the signal that be measured, electron beam is like the nib of a pen, the metabolic curve of the instantaneous value of a signal that be measured can be depicted on screen face. The undee curve that uses oscillograph to be able to observe all sorts of different signal extent change along with time, still can check all sorts of different n with it, if voltage, electric current, frequency, phasic difference, amplitude modulation is waited a moment.
, the working principle of oscillograph
(one) the composition of oscillograph is common oscillograph has 5 main component: Indication circuit, perpendicular (Y axis) enlarge circuit, level (X axis) circuit of scanning and enlarge circuit, synchronous circuit, power source supply. The principle function block diagram of common oscillograph is shown like graph 5-1 place.
1. Indication circuit
Indication circuit includes oscilloscope tube to reach its to dominate circuit two parts. Oscilloscope tube is a kind of special valve, it is oscillograph a main component. If graph 5-2 place is shown,the fundamental of oscilloscope tube pursues. See by the graph, oscilloscope tube is comprised 3 times partly by system of electron gun, deflexion and fluorescent screen.
(1) electron gun
Electron gun is used at generation and form high speed, get together bundle the electron flows, go the glow that bombard fluorescent screen makes. It is main by G of K of filament F, cathode, control pole, the first zincous A1, the 2nd positive pole A2 is comprised. Outside dividing filament, the structure of the others electrode is metallic cylinder, and their axes maintains go up in same axes. After cathode is heated, can launch an electron along axial; Control is negative potential for extremely opposite cathode, change potential can change flexible to control the electronic amount of dinky aperture too, control the brightness of the spot on fluorescent screen namely. Nod brightness to raise screen glazing, do not reduce the sensitivity of pair of electron beam deflexion again, in contemporary oscilloscope tube, electrode A3 is quickened after on one still is added between deflexion system and fluorescent screen.
Interior of graph 5-2 oscilloscope tube structural sketch map
The positive electricity that has about hundreds of hot season is added to press the first zincous anticathode. Add on the 2nd positive pole a taller than the first positive pole positive electricity is pressed. Cross the electron beam that dominates dinky opening, below the first positive pole and the action of the 2nd zincous high potential, get acceleration, make high speed move to fluorescent screen direction. Because the same sex of charge is exclusive, electron beam is met gradually diffuse. Carry the first positive pole, the 2nd positive pole between the focusing action of electric field, make the electron gathers to rise and be handed in afresh collect at a bit. Proper control the first positive pole and between the 2nd positive pole the size of voltage, can make the focus just falls on fluorescent screen, show a shining and petty dot. Change the first positive pole and the voltage between the 2nd positive pole, can rise adjust the action of spot focusing, this is oscillograph " focusing " and " auxiliary focusing " adjusted principle. Interior of oscilloscope tube cone besmears the 3rd positive pole a black lead is formed, add normally have very tall voltage, it has 3 effect: ① makes cross deflexion system the following electron is quickened further, make the electron has enough energy to go bombard fluorescent screen, in order to achieve enough brilliance; Besmear of layer of ② black lead is on whole cone, can have screen effect; Fluorescent screen of bombard of ③ electron beam can produce an electron 2 times, the A3 that is in high potential can absorb these electrons.
Previous12 Next