Kinematic support structure
A kinematic support structure of a “groove-groove-groove” type that reduces friction between a first base and a second base is provided. In the kinematic support structure, a first base comprises three grooves and a second base comprises three other grooves. Balls are all movable with respect to the first base and the second base. Two grooves corresponding in the two bases face each other across respective one of the balls.
1. A kinematic support structure, comprising:
a first support member comprising a first elongated groove portion, a second elongated groove portion and a third elongated groove portion;
a second support member comprising a fourth elongated groove portion, a fifth elongated groove portion and a sixth elongated groove portion; and
a first ball, a second ball and a third ball all movable with respect to the first support member and the second support member, wherein:
the first elongated groove portion and the fourth elongated groove portion face each other across the first ball;
the second elongated groove portion and the fifth elongated groove portion face each other across the second ball; and
the third elongated groove portion and the sixth elongated groove portion face each other across the third ball, and wherein the first support member comprises:
a first ball holding structure for restricting a position of the first ball within a first travel range;
a second ball holding structure for restricting a position of the second ball within a second travel range; and
a third ball holding structure for restricting a position of the third ball within a third travel range, and wherein:
the travel ranges have respective finite expanses;
the first ball holding structure includes an elastic member for pushing the first ball in an inward direction of the first travel range;
the second ball holding structure includes an elastic member for pushing the second ball in an inward direction of the second travel range; and
the third ball holding structure includes an elastic member for pushing the third ball in an inward direction of the third travel range.
2. The kinematic support structure as claimed in claim 1 , wherein:
the first elongated groove portion, the second elongated groove portion and the third elongated groove portion are arranged in a radial configuration;
the fourth elongated groove portion, the fifth elongated groove portion and the sixth elongated groove portion are arranged in a radial configuration;
the first elongated groove portion abuts on the first ball at two points;
the elongated second groove portion abuts on the second ball at two points;
the elongated third groove portion abuts on the third ball at two points;
the elongated fourth groove portion abuts on the first ball at two points;
the elongated fifth groove portion abuts on the second ball at two points; and
the elongated sixth groove portion abuts on the third ball at two points.
3. A kinematic support structure, comprising:
a first support member comprising a first elongated groove portion, a second elongated groove portion and a third elongated groove portion;
a second support member comprising a fourth elongated groove portion, a fifth elongated groove portion and a sixth elongated groove portion; and
a first ball, a second ball and a third ball all movable with respect to the first support member and the second support member, wherein:
the first elongated groove portion and the fourth elongated groove portion face each other across the first ball;
the second elongated groove portion and the elongated fifth groove portion face each other across the second ball; and
the third elongated groove portion and the sixth elongated groove portion face each other across the third ball, and wherein
the kinematic support structure comprises a ball holding structure switchable between a fixed ball state and a travelable ball state.
4. The kinematic support structure as claimed in claim 1 , further comprising pressing means for pushing the first support member and the second support member toward each other.
5. The kinematic support structure as claims in claim 3 , wherein
the ball holding structure comprises a pair of holding members;
the pair of holding members are spaced apart from the first support member by a first distance in the fixed ball state; and
the pair of holding members is spaced apart from the first support member by a second distance greater than the first distance in the travelable ball state.
6. The kinematic support structure as claimed in claim 3 , wherein:
the first elongated groove portion, the second elongated groove portion and the third elongated groove portion are arranged in a radial configuration;
the fourth elongated groove portion, the fifth elongated groove portion and the sixth elongated groove portion are arranged in a radial configuration;
the first elongated groove portion abuts on the first ball at two points;
the second elongated groove portion abuts on the second ball at two points;
the third elongated groove portion abuts on the third ball at two points;
the fourth elongated groove portion abuts on the first ball at two points;
the fifth elongated groove portion abuts on the second ball at two points; and
the sixth elongated groove portion abuts on the third ball at two points.
7. The kinematic support structure as claimed in claim 3 , further comprising pressing means for pushing the first support member and the second support member toward each other.