The working principle of the television

From;    Author:Stand originally
The working principle of monochrome television machine

The circuit of monochrome television machine is scanned by enlarge of passageway of high frequency tuning, image, audio passageway, video, synchronism, picture tube and its circuit and power source composition.

After antenna of composite signal classics is received, enter high frequency tuner above all inside (common weighs high frequency head) , after passing high frequency enlarge and frequency conversion, form the intermediate frequency signal of unified frequency, send image intermediate frequency enlarge circuit. Because the television uses the form of the carrier wave inside superheterodyne type (as us common superheterodyne type radio is same) , the signal of will different frequency is changed into intermediate frequency signal of the standard, this works with respect to the stability that is a television and adjust convenient, provided requirement. Composite signal (incorporate image, audio, synchronous signal) after the 3 class intermediate frequency that passes image passageway magnifies, undertake demodulation via video radiodetector again, take out signal of image, audio, send toward video enlarge electric equipment and audio passageway respectively. After magnifying the picture signal that sends video enlarge circuit, input the function that replay image realizes in picture tube; After the audio signal classics that sends audio the passageway magnifies, drive loudhailer to realize replay audio function.

Send and be being received of TV image is support electron scanning to image decompose what will come true with synthesis, if want to make sure the electron that television and TV station launch scans,ordinal safety agrees, be about to install synchronous scanning circuit inside the television. Synchronous scanning circuit takes out the synchronous signal in composite signal to try to handle, with travel, frame scanning circuit controls the deflexion of the electron beam in picture tube, stable picture returns on picture tube.

Picture tube is a kind of CRT, to make picture tube can be given out brightness, heavy show picture, need increases the dc maximum pressure of 10 thousand more than bend over on its positive pole. The travel output transformer that should having scanning circuit share so is sub produce a very tall pulse tension, classics commutate evacuation comes picture tube is zincous.

Power source part provides a TV set the working voltage of each part circuit.

The general principle of colour television machine

As a result of historical reason, when inventing colour television machine, monochrome television machine has been used extensively socially, to still can use original equipment system, can make colour television signal and monochrome television receive kind only compatible.

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