Isochronism (1): As a Keyword of Japanese Mechanical Horology

Abstract

  In this chapter 1, the fundamental equation of vibration for the free damped case and its power consumption are described. The consumption power of the balance-spring system should be regarded as the solid friction resistance of the pivot of the balance staff and the viscous resistance of balance-wheel rotating in the air. Moreover, the relationship between the Q value which represents the goodness of the vibration system and the frequency of vibration, effect of high vibration frequency and the improvement of wearing accuracy are described. In chapter 2 in the next book, basic theory of isochronism, the nonlinearity portion of hairspring action. In chapter 3, explanation of isochronism of horizontal positions, mainly based from the outer end fixation of hairspring. In chapter 4, explanation of the isochronism of vertical positions based on the unbalance moment of inertia of balance-wheel and the inner terminal fixation of hairspring. Weighing method of middle place of hairspring is explained here.