High acceleration spindle drive and method of using same

1. An apparatus for moving a spindle along a longitudinal axis, the apparatus comprising:

a spindle;

a drive member for moving said spindle over a range of travel along said longitudinal axis in a first direction;

means for applying a first force in combination with a second force to the spindle in the first direction;

a stop element arranged so as to disengage the second force, such that when said spindle is within a first portion of said range of travel, said first force is applied to said spindle in combination with said second force, and when said spindle is within a second portion of said range of travel, said stop element disengages said second force so only said first force is applied to said spindle.

2. The apparatus of claim 1 , wherein the drive member moves the spindle with an acceleration exceeding 20 g.

3. The apparatus of claim 1 , wherein the spindle can remain stationary by application of only the first force.

4. The apparatus of claim 1 , further comprising means to generate a machine readable signal when only the first force is applied and the spindle is stationary.

5. The apparatus of claim 4 , wherein the means to generate a machine readable signal includes a strain guage.

6. A spindle driving assembly comprising:

a spindle;

a spindle drive member mounted for movement from a first position to a second position through a range of movement;

a first spring pressing on the spindle either directly or indirectly with a first force;

a second spring pressing a second force on the spindle in the spindle driving assembly either directly or indirectly; and

a stop element arranged to disengage the force of the of the second spring so that when the drive member is within a first portion of the range of movement, the first spring and the second spring press forces on the spindle and when the drive member is in a second portion of the range of movement, the stop element disengages the force applied by the second spring on the spindle;

wherein movement of the drive member drives the spindle.

7. The apparatus of claim 6 , wherein during the first portion of the range of travel the spindle accelerates with an acceleration exceeding 20 g.

8. A method of moving a spindle along a longitudinal axis, the method comprising:

moving said spindle with acceleration during a first portion of a range of travel along said longitudinal axis;

moving said spindle with deceleration during a second portion of a range of travel along said longitudinal axis,

applying a first force and a second force to the spindle, either directly or indirectly, during the spindle acceleration in order to counter any resistance of the spindle to the acceleration;

disengaging the second force; and

applying only the first force to the spindle, either directly or indirectly, during the spindle deceleration.

9. The method of claim 8 , wherein the spindle moves with an acceleration exceeding 20 g during the first portion of the range of travel.