Patent ID: 6920936

Claim:
A method for imparting a substantially constant force to an object, comprising: positioning a constant force actuator adjacent the object, the constant force actuator having a pair of force transmitting members disposed for relative linear movement, at least one of said force transmitting members being linearly movable, and a linkage in force receiving relation with said force transmitting members and having a first force transmitting element movable by said linkage in a direction substantially perpendicular to said relative linear movement of said force transmitting members and disposed for force transmitting contact with an object, said linkage having a movement control guide of predetermined movement control geometry in force reacting engagement with at least one of said force transmitting members and translating said relative linear movement of said force transmitting members to expansion and contracting movement of said linkage and linear movement of said first force transmitting element, said method comprising: initiating expansion movement of said constant force actuator by causing relative linear movement of said force transmitting members toward one another and causing reaction of said movement control geometry with at least one of said force transmitting members and developing a linkage movement force oriented for expansion movement of said linkage and developing a substantially constant linkage transmitting force on said first force transmitting element; continuing expansion movement of said constant force actuator by continuing said relative linear movement of said force transmitting members until a predetermined intermediate angular relation of said linkage has been reached and said predetermined movement control geometry and said at least one force transmitting member have separated; further continuing expansion movement of said constant force actuator by continuing said relative linear movement of said force transmitting members with said force transmitting members acting directly on said linkage until desired extension of said linkage and desired movement of said first force transmitting element have been achieved.