Quartz clock is a kind of clock driven by current, but it is different from ordinary electric clock. There is a timely crystal in it. When current passes, the crystal oscillates due to voltage. Its oscillation frequency is very stable, and the controlled electronic oscillator makes the travel time very accurate. The best quartz clock has a time difference of 1 second every 1000. The observatory not only uses it to time, but also uses it to measure the change of the earth's rotation speed.

The natural single crystal is crystal, which chemists call silicon dioxide, which is a compound of silicon dioxide. Crystal can not only be used as an ornamental handicraft, but more importantly, it is an "important corner" of the electronic industry.

1880, French scientists pierre curie and Jacques Curie discovered this important phenomenon in physics. They cut the crystal into parallel slices, put them between two metal plates, and squeeze or stretch the slices under the action of external gravity. A strange phenomenon appeared: charges with opposite signs gathered at both ends of the wafer.

This characteristic of the crystal can make the crystal sheet vibrate at high frequency under the action of alternating current, resulting in ultrasonic oscillation.

During the first world war, Germany suddenly attacked the British and French allied forces with submarines, and the ship sank, making the British navy lose its advantage. Later, French physicist Lange made the world's first ultrasonic detector by using the principle that crystal slices discovered by Curie brothers can generate ultrasonic waves. This instrument is placed on a warship, and when it encounters obstacles, it will emit sound waves and reflect them back. After receiving the echo, the instrument can detect the position of the enemy submarine, thus effectively preventing the sudden attack of the enemy submarine and mastering the initiative in the war.

The crystal resonator made by cutting the crystal into single pieces is indispensable for making the chronoelectrometer and chronometer. Satellites, missiles, planes, ships, electron microscopes, televisions, telegrams, telex, broadcasting and so on all need it.

The vibration frequency of the crystal is very stable. The general frequency in the electronic watch is 32768Hz, while the oscillation frequency in the high-frequency quartz watch reaches 4 194304Hz, so the time is very accurate.

The electronic watch is composed of quartz crystal oscillator, oscillator circuit, frequency divider circuit, shaping amplifier circuit and micro motor, which are integrated on a small silicon chip through integrated circuits. It can output a pulse electrical signal every 1 sec. The vibration frequency is fast, the travel time is accurate, and the monthly error is 5 ~ 15 seconds. An amplifier circuit is used to turn the electrical signal into a strong current to drive the motor, which is the pointer quartz watch.

Since the 1960s, quartz clocks have been greatly improved, and the daily difference is generally less than 50 ~ 500 microseconds.