Frequency on an automatic watch, what is it ?

In watchmaking, the frequency of the movement is a real asset, and many brands have embarked on a race to increase the oscillation speed and performance of their watches. watches. The frequency of a watch corresponds to the number of oscillations made by the balance wheel in one hour. There are two types of measurement for evaluating the frequency of an automatic movement. : Hertz and the number of alternations per hour (A/h). The higher the frequency of a watch, the more precise the oscillations of its balance wheel will be. It is these oscillations of an automatic balance wheel watch that produce the ticking sound.

The link between the balance wheel and the frequency of a watch

• The balance wheel is the regulating organ of the watch. It channels the energy received by the escapement, thus allowing the hands to rotate at regular and precise intervals. It is the oscillations of the balance wheel that cause the hands to move.
• The balance wheel receives mechanical energy through the pallet fork, allowing it to rotate. This is the "click" we hear. At the center of the balance wheel is a spiral that compresses under the effect of the balance wheel's rotation. As it expands, the spiral forces the balance wheel to swing back: this step is indicated by the "tap" we hear. The oscillation is therefore the back-and-forth movement of the balance wheel, and is thus composed of two alternations.
• The frequency is the number of oscillations the pendulum makes in one second. However, the frequency of a automatic watch measured in the number of vibrations per hour or in Hertz. Thus, a watch with 28 800 alternations per hour performs 14 400 oscillations in one hour, 240 oscillations per minute, and 4 oscillations per second. To express To calculate the frequency in Hz, you must divide the number of oscillations per hour by 7200. Thus, a mechanical watch with a frequency of 28 800 A/h will have a frequency of 4Hz.

Relationship between frequency and accuracy of a watch

• The higher the frequency—in other words, the more oscillations the balance wheel makes per second—the more accurate the watch will be and the smoother the movement of the hands (especially the seconds hand). However, it should be noted that on some movements, too high a frequency can lead to premature wear and also reduce the power reserve.
• Most mechanical watches have frequencies of 21 600 A/H or 28 800 A/H even though there are watches with frequencies up to 36 000 cycles in one hour, or 10 cycles in one second. With this type of movement, the rhythm of the second hand is smooth; the increments are no longer visible.
• All Charlie Paris automatic watches operate at a frequency of 28,800 A/H, or 4Hz. This frequency allows our automatic watches to achieve an accuracy of approximately ± 20 sec.