On modern mechanical clocks, there are mainly two kinds of timing accuracy: the simple pendulum commonly used in watches and the hairspring system commonly used in watches; Under the condition of free oscillation, both time benchmarks have stable periods. Because controlling the escapement consumes energy, its own friction and air resistance also lead to energy loss, so the oscillating system needs to constantly supplement the lost energy through the escapement to make the balance wheel (or simple pendulum) achieve the dynamic balance of energy input and output, which is the "impact transmission process".
Mathematical analysis shows that this "transfer process" will affect the period of timing reference, and some random timing errors will appear during the transfer process. However, under certain conditions, the influence of this process on the timing reference period can be reduced or eliminated:
1. "When the transmission part or external impact occurs at the balance point (the position when the balance wheel or the simple pendulum stops), the timing period is unchanged.
2. Increasing the interval of free oscillation can effectively reduce the relative size of the error interval of "transmission shock"
3. For the balance spring system, if the swing amplitude can be controlled at 220 degrees, the oscillation frequency of the oscillation system will remain unchanged no matter what impact it is subjected to.
The above conditions are the theoretical basis for the continuous improvement of the escapement mechanism. Coaxial escapement mechanism, precision escapement mechanism and constant force escapement mechanism are new types of mechanisms that have greatly improved the existing escapement mechanism under the guidance of the above ideas.