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Telephone [English: telephone, from Greek τ? λε(tēle, meaning "far") and φ ω ν? (ph n ē, meaning "sound"), the old translation is a long-distance communication device, which can transmit and receive sound. As early as the18th century, there was a word "telephone" in Europe, which was used to refer to microphones strung together with wires (cups strung together with wires).

The telephone was attributed to Alexander Graham Bell. The principle of early telephone is that sound is a compound vibration in the air, which can be transmitted to solids and to conductive metals through electric pulses. Bell applied for the telephone patent in March 1876.

Development history

The telephone was invented by American A.G. Bell in 1876. He used two wires to connect two transmitters and receivers with the same structure and a diaphragm on the electromagnet to realize the communication between the two ends first. But the call distance is short and the efficiency is low. Carbon microphone appeared in 1878, which greatly improved the efficiency of telephone microphone.

The receiver structure has also been improved. The earliest telephone was a magnet telephone, which was powered by its own battery and sent a call signal with a hand-cranked generator.

1880 * * electric telephone appeared, which was powered by * * * electric switch in a centralized way, saving the hand-broadcast generator and dry battery. 189 1 year, rotary dial-up automatic telephone appeared, which can send out DC dial-up pulse, control the action of automatic exchange, select the called user and automatically complete the transfer function. Thus pushing telephone communication to a new stage.

By the end of 1960s, push-button all-electronic telephone appeared. In addition to pulse signaling, DTMF signaling also appeared. With the development of program-controlled switches, dual-tone telephone is becoming more and more popular. Electronic telephone circuits are developing towards integration, and telephone application specific integrated circuits have been widely used in various components of telephone circuits.

Various multifunctional telephones and special telephones have also emerged. By the early 1990s, there had been a telephone which integrated the functions of dialing, talking and ringing on an integrated circuit. With the development of speech recognition technology, a new type of telephone that dials directly by voice is also emerging.