Actuator

• US 6,459,855 B1
• Filed: 05/08/2000
• Issued: 10/01/2002
• Est. Priority Date: 05/18/1999
• Status: Expired due to Fees

• Current Assignee: Minolta Corporation Limited (Konica Minolta Inc.)
• Original Assignee: Minolta Corporation Limited (Konica Minolta Inc.)
• Inventors: Minato, Shoichi, Kosaka, Akira, Tanaka, Yoshiharu, Tanii, Junichi
• Primary Examiner(s): Mathews, Alan A.
• Application Number:
  US09/567,478
• Time in Patent Office: 876 Days
• Field of Search: 396/176, 396/177, 396/178, 396/358, 396/443, 396/535, 396/538, 396/439
• US Class Current: 396/177
• CPC Class Codes: G03B 17/38 Releasing-devices separate from shutter integral with shutter G03B9/08
• CPC Class Codes: G03B 9/08 Shutters

Abstract

An actuator applied with shape memory alloy which can be operated in a wide operating temperature range and has a long life time. At a normal ambient temperature, when the first wire of the acting member made of shape memory alloy in which predetermined shape is memorized in advance, is heated, it is transformed to the memorized shape to enable the acting member to be moved. A relative low stress is generated at the first wire and its life-time is not shortened. In the case that the ambient temperature is increased to exceed a transformation starting temperature of the shape memory alloy, the second wire of shape memory alloy is transformed to the memorized shape to generate a high stress at the first wire and to increase the transformation starting temperature of the first wire. With such an arrangement as above, it is possible to operate the actuator applied with the shape memory alloy in a wide operating temperature range.

Claims

1. An actuator comprising:

a moving member biased in a predetermined direction;

an engaging member for engaging with and stopping a movement of said moving member in the predetermined direction;

a first acting member connected to said engaging member and starting a shape transformation upon reaching a first temperature to move said engaging member to release an engaged state of the moving member with the engaging member; and

a second acting member effecting an operational response upon being heated by ambient temperature to a second temperature, lower than said first temperature, the operational response of said second acting member at the second temperature preventing movement of the engaging member by said first acting member when said first acting member starts said shape transformation.

2. An actuator according to claim 1, wherein said first acting member is constituted by a wire of shape memory alloy.

3. An actuator according to claim 1, wherein said second acting member is constituted by a wire of shape memory alloy.

4. An actuator according to claim 1, wherein said second acting member is constituted by a bimetal.

5. An actuator according to claim 1, further comprising

a heating member for heating said first acting member.

6. An actuator according to claim 1 further comprising;

a frame and a pin fixed to said frame, wherein said engaging member is a lever, one end of said lever is engaged with said moving member, and the other end is fixed to said pin and rotatable around said pin.

7. An actuator according to claim 1, wherein said moving member is a flash unit of a camera.

8. An actuator comprising:

a first acting member starting a shape transformation upon reaching a first temperature;

a second acting member starting a shape transformation upon reaching a second temperature, lower than the first temperature, when heated by ambient temperature;

a connecting member connected to an engaging member via the first acting member, said connecting member being driven by said shape transformation of the second acting member to loosen a connection tension of said first acting member connecting said connecting member and said engaging member; and

a moving member biased in a predetermined direction and engaged with said engaging member to stop movement of said moving member in the predetermined direction, starting of movement of the moving member in the predetermined direction being effected when the engagement of the engaging member with the moving member is released via said shape transformation of said first acting member.

9. An actuator comprising:

a heating member;

a first acting member starting a variation in shape when heated by said heating member to a first temperature;

an engaging member connected to said first acting member;

a moving member biased in a predetermined direction and engaged with said engaging member to stop movement of said moving member in the predetermined direction, starting movement of the moving member in the predetermined direction being effected when the engaged state of the engaging member with the moving member is released through the variation in shape of the first acting member when heated to the first temperature; and

a second acting member starting a variation in shape when heated by ambient temperature to a second temperature, lower than the first temperature, and the variation in shape of the second acting member when heated to the second temperature preventing release of the engaged state of the engaging member even when the first acting member starts a variation in shape when heated to the first temperature.

10. An actuator comprising:

a first acting member having a first end and a second end, the first acting member beginning to shrink upon reaching a first temperature;

a connecting member connected to the first end of said first acting member and moved in a shrinking direction of the first acting member;

a second acting member beginning a shape transformation upon reaching a second temperature, lower than the first temperature, when heated by ambient temperature and causing said connecting member to be moved in the shrinking direction of said first acting member;

a heating member for heating said first acting member;

an engaging member connected to the second end of said first acting member; and

a moving member biased in a predetermined direction, engaged with said engaging member to stop movement of said moving member in the predetermined direction, starting of movement of said moving member in the predetermined direction being effected when the engagement of said engaging member with the moving member is released via shrinkage of said first acting member when heated by said heating member to the first temperature.

11. An actuator comprising:

a first acting member having a first end and a second end, the first acting member beginning to shrink upon reaching a first temperature;

a connecting member connected to the first end of said first acting member and moved in a shrinking direction of the first acting member;

a resilient member;

an engaging member connected to the connecting member by said resilient member;

a second acting member beginning a shape transformation upon reaching a second temperature, lower than said first temperature, when heated by ambient temperature and causing said connecting member to be moved in the shrinking direction without moving said engaging member;

a heating member for heating said first acting member; and

a moving member biased in a predetermined direction and engaged with said engaging member to stop movement of said moving member in the predetermined direction, starting of movement of said moving member in the predetermined direction being effected when the engagement of said engaging member with the moving member is released via shrinkage of said first acting member when heated by said heating member to the first temperature.

12. An actuator comprising:

a first acting member starting a shrinkage transformation upon reaching a first temperature;

a second acting member starting a shrinkage transformation upon reaching a second temperature, lower than the first temperature, when heated by ambient temperature;

a heating member to heat said first acting member;

an engaging member connected to said first acting member; and

a moving member biased in a predetermined direction and engaged with said engaging member to stop movement of said moving member in the predetermined direction, starting of movement of said moving member in the predetermined direction being effected when the engagement of said engaging member with the moving member is released via starting said shrinkage transformation of said first acting member when heated by said heating member to the first temperature.

13. An actuator according to claim 12, wherein said first member is constituted by a wire of shape memory alloy.

14. An actuator according to claim 12, wherein said second member is constituted by a wire of shape memory alloy.

15. An actuator comprising:

a first acting member constituted by a shape memory alloy and starting to shrink in a shrinking direction upon reaching a first temperature;

an engaging member connected to said first acting member;

a heating member to heat said first acting member;

a moving member biased in a predetermined direction and engaged with said engaging member to stop movement of said moving member in the predetermined direction, starting of movement of said moving member in the predetermined direction being effected when the engagement of said engaging member with the moving member is released via shrinkage of said first acting member when heated by said heating member to the first temperature; and

a second acting member starting a shape transformation upon reaching a second temperature, lower than said first temperature, when heated by ambient temperature, the shape transformation pulling the first acting member toward a direction opposite to the shrinkage direction of said first acting member and increasing a connection tension of the connection of said first acting member with the engaging member.

16. An actuator comprising:

a first acting member starting a shape transformation upon reaching a first temperature;

an engaging member connected to said first acting member and driven by said shape transformation of said first acting member;

a moving member engaged with said engaging member to stop movement of said moving member, the engagement of said engaging member with the moving member being released when said first acting member starts a shape transformation;

a second acting member starting a shape transformation upon reaching a second temperature, lower than said first temperature, when heated by ambient temperature; and

an invalidating means responsive to said shape transformation of said second acting member for preventing movement of said moving member even when said engaging member is driven by said shape transformation of said first acting member.

17. An actuator comprising:

a first acting member starting a shrinkage transformation upon reaching a first temperature;

an engaging member connected to said first acting member;

a heating member to heat said first acting member;

a moving member biased in a predetermined direction and engaged with said engaging member to stop movement of said moving member, the engagement of the engaging member with the moving member being released through the shrinkage transformation of the first acting member heated to the first temperature by said heating member;

a second acting member starting a shape transformation upon reaching a second temperature, lower than said first temperature, when heated by ambient temperature; and

a blocking member moved via said shape transformation of said second acting member to prevent movement of said moving member even when said first acting member starts said shrinkage transformation.