Patent ID: 8807827
Filing Date: 2014-08-19
Classification: G04B

Abstract:
1. A detent escapement for a timepiece, the detent escapement comprising: an escape wheel and pinion; a balance having an impulse pin for contacting a tooth portion of the escape wheel and pinion, and having an unlocking jewel; a blade having a locking jewel for contacting the tooth portion of the escape wheel and pinion; and a single blade spring provided on the blade for contacting the unlocking jewel; wherein a tip of the single blade spring contacting the unlocking jewel of the balance and applying resistance to the balance before the unlocking jewel of the balance passes through an oscillation center is defined as “resistance before dead point”, wherein the tooth portion of the escape wheel and pinion contacting the impulse pin of the balance and applying force with respect to an advancing direction of the balance before the unlocking jewel of the balance passes through the oscillation center is defined as “impact before dead point”, wherein the tooth portion of the escape wheel and pinion pressing the impulse pin of the balance and applying a force with respect to an advancing direction of the balance after the unlocking jewel of the balance passes through the oscillation center is defined as “impact after dead point”, wherein the tip of the single blade spring contacting the unlocking jewel of the balance and applying resistance to the balance after the unlocking jewel of the balance passes through the oscillation center, and the tip of the blade spring contacting the unlocking jewel of the balance and applying resistance to the balance when the unlocking jewel of the balance passes through the oscillation center, returns toward the oscillation center, and the unlocking jewel of the balance passes through the oscillation center are defined as “resistance after dead point”, wherein a straight line, defined as a rotation center line, passes through a rotation center of the blade and through a rotation center of the balance in a state where the unlocking jewel of the balance is positioned at the oscillation center, and wherein in a state where the unlocking jewel is positioned at the oscillation center, the unlocking jewel is disposed at a position in which the unlocking jewel is rotated by a preselected angle from the rotation reference line toward a direction away from the escape wheel and pinion so that the sum of influences that advance the timing rate of the timepiece, including the sum of the influence on the rotational movement of the balance which is generated by “impact before dead point” and the influence on the rotational movement of the balance which is generated by “resistance after dead point”, and the sum of influences that delay the timing rate of the timepiece, including the sum of the influence on the rotational movement of the balance which is generated by “resistance before dead point” and the influence on the rotational movement of the balance which is generated by “impact after dead point” are balanced to each other.