Speed governor for timepiece

Patent metadata

Field	Value
Publication number	US-10274897-B2
Application number	US-201615736695-A
Country	US
Kind code	B2
Filing date	Jun 1, 2016
Priority date	Jun 15, 2015
Publication date	Apr 30, 2019
Grant date	Apr 30, 2019

Abstract

A governor includes a balance spring including a base member made of silicon, for example, and a balance wheel. The balance spring includes a coating film of DLC that is applied to a surface of the silicon base member to improve the strength of the balance spring. A spring constant of the balance spring changes in accordance with the temperature change. A moment of inertia of the balance wheel changes in accordance with the temperature change. A change in an oscillation period due to the temperature change is suppressed by the change in the spring constant of the balance spring and by the change in the moment of inertia of the balance wheel.

First claim

What is claimed is:

1. A governor for a timepiece comprising:
a balance spring, and
a balance wheel,
wherein the balance spring comprises a base member that has a spiral shape, and a coating film that is applied to a surface of the base member to improve strength of the balance spring,
wherein a spring constant of the balance spring changes in accordance with a temperature change,
wherein a moment of inertia of the balance wheel changes in accordance with the temperature change,
wherein a change in an oscillation period due to the temperature change is suppressed by a change in the spring constant of the balance spring and by a change in the moment of inertia of the balance wheel,
wherein the balance wheel comprises
a balance staff,
a support member that extends radially outward from the balance staff as a center, and
a weight member that is supported by the support member and extends radially inward from a supported portion of the weight member, and

wherein a coefficient of thermal expansion of the weight member in accordance with the temperature change is larger than a coefficient of thermal expansion of the support member.

2. The governor according to claim 1 , wherein a temperature coefficient of the spring constant of the balance spring is smaller than that of a spring constant of the base member.

3. The governor according to claim 2 , wherein the coating film is made from a diamond-like carbon or a resin.

4. The governor according to claim 1 , wherein a temperature coefficient of the spring constant of the balance spring is larger than that of a spring constant of the base member.

5. The governor according to claim 4 , wherein the coating film is made from silicon dioxide.

6. The governor according to claim 1 , wherein the balance wheel comprises a weight member that changes the moment of inertia of the balance wheel in accordance with the temperature change.

7. The governor according to claim 1 , wherein the weight member includes a radially inner end and a radially outer end in an entire length of the weight member that extends in a radial direction, and wherein the weight member is supported by the support member at a position that is defined such that a length between a supporting position of the supporting member and the radially inner end is longer than a length between the supporting position and the radially outer end.

8. The governor according claim 1 , wherein the weight member is supported by the support member at a radially outer end in an entire length of the weight member that extends in a radial direction.

Assignees

• Citizen Watch Co Ltd

Inventors

• Ikeda Tomoo
• Niida Yusaku
• Abe Yosuke

Classifications

• G04B17/066

  Manufacture of the spiral spring (locking of the spiral spring by the regulating lever G04B18/026; spiral spring with temperature compensation G04B17/227; fixation of the spiral spring on the collet G04B17/32; mainspring G04B1/14) · CPC title

• G04B17/063

  Balance construction (balances with frequency adjustment screw G04B18/006; balances with temperature compensation G04B17/222; balancing devices G04B17/28) · CPC title

• G04B17/222 Primary

  with balances (construction of balances G04B17/063) · CPC title