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The indication principle of oscillograph
From;    Author:Stand originally
Oscillograph of principle of 1 oscillograph job is the character that uses electronic oscilloscope tube, person eye cannot of direct observation hand in become telegraphic date is changed into image, show the electron that so that measure,goes up in fluorescent screen measures an instrument. It is observation the problem in experiment of phenomenon of digital circuit experiment, analysis, measure the important instrument with experimental indispensable result. Oscillograph is mixed by oscilloscope tube composition of source of signal of system of scanning of system of deflexion of axis of system of power source system, synchronous system, X axis deflexion, Y, defer, standard. 1. 1 oscilloscope tube
CRT (CRT) abbreviation oscilloscope tube, it is the core of oscillograph. It changes telegraphic name the signal that it is light. System of electron gun, deflexion and fluorescent screen 3 parts are sealed inside case of glass of a vacuum, made a complete oscilloscope tube.

1. Fluorescent screen
Face of present oscilloscope tube screen is rectangular plane normally, inside material of a phosphorescence makes exterior deposit fluorescent film. On fluorescent film Chang Youzeng adds to evaporate aluminous film. High speed electron crosses aluminous film, bump fluorescent material and glow forms window. Aluminous film is had inside reflection action, those who be helpful for raising window brightness degree. Aluminous film still has medicinal powder the other action such as heat.
After the electron stops bombard, window cannot disappear instantly and want to retain period of time. Window brightness spends the time that drops to be passed to the 10 % place of original value to be called " twilight time " . Twilight time is short it is extremely short twilight at 10 μ S, 10 μ S, 1ms is short twilight, 1ms, 0. 1s is in twilight, 0. 1s-1s is long twilight, be more than 1s to be extremely long twilight. General oscillograph is deployed in twilight oscilloscope tube, high frequency oscillograph chooses short twilight, low frequency oscillograph chooses long twilight.
Because what use phosphorescence material to differ, what different color can give out on fluorescent screen is smooth. General oscillograph uses the oscilloscope tube that sends green light more, with tutelar eye. 2. Electron gun reachs focusing
Electron gun by filament (F) , cathode (K) , grid (G1) , before quickly extremely (G2)(or weigh the 2nd grid) , the first positive pole (A1) and the 2nd positive pole (A2) composition. Its action is to launch an electron to form very fine high speed electron beam. Filament electrify heats cathode, cathode be heated launchs an electron. Grid is canister of garden of metal of cribriform of a coping, cover outside cathode. Because grid potential is lower than cathode, the electron that anticathode launchs has control effect, have a few electrons with athletic big initial velocity only commonly, grid alveolus can be crossed below the action of zincous voltage, run quickly to fluorescent screen. The electron with small initial velocity still returns cathode. If grid potential is too low, all electron returns cathode, namely pipe ends. Adjust the W1 potentiometer in circuit, can change grid potential, control shoots the electron to fluorescent screen to shed density, achieve thereby adjust of window brightness degree. Before the first positive pole, the 2nd positive pole is mixed, be extremely quickly be in with cathode same a 3 metals cylinder on axes. Quicken before extremely G2 and A2 are linked together, what increase potential taller than A1. The positive electricity of G2 anticathode electron goes straight towards Xiang Ying effect is accelerated since optical screen.
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