Dynamic lead screw engagement and indicator
First Claim
1. An engagement system for engaging the threads of a lead screw with the threads of a screw drive mechanism, the screw drive mechanism operating to translate the rotational motion of the lead screw into linear motion, the system comprising:
- a motor coupled to the lead screw which selectively rotates the lead screw;
an engagement mechanism mounted to the screw drive mechanism to selectively move the screw drive mechanism threads into and out of engagement with the threads of the lead screw;
an engagement detector which senses the position of the engagement mechanism and provides an engagement signal representative of the engagement mechanism being in a position to cause engagement of the threads of the screw drive mechanism with the threads of the lead screw; and
a processor which receives the engagement signal and controls the motor to cause the lead screw to rotate for a predetermined time period when the engagement signal indicates that the threads are not engaged.
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0 Petitions
Accused Products
Abstract
Automatic engagement of a lead screw with a lead screw drive mechanism. A plunger driver used to move the plunger of a syringe is connected to the screw drive mechanism. A first detector provides a plunger signal indicating the presence of a syringe plunger in the plunger driver and a second detector provides a thread engagement signal indicating engagement or disengagement of the lead screw drive mechanism with the lead screw. The thread engagement detector monitors movement of a rigid linkage at the screw drive mechanism which has a nonlinear characteristic curve. In the case where the plunger signal indicates the presence of a plunger and the thread engagement signal indicates engagement of the drive mechanism with the lead screw, the lead screw is rotated in a forward direction to remove the thread clearance. In the case where the thread engagement signal indicates disengagement of the drive mechanism with the lead screw, the processor rotates the lead screw first in a reverse direction and then in a forward direction to cause engagement of the threads.
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Citations
19 Claims
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1. An engagement system for engaging the threads of a lead screw with the threads of a screw drive mechanism, the screw drive mechanism operating to translate the rotational motion of the lead screw into linear motion, the system comprising:
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a motor coupled to the lead screw which selectively rotates the lead screw; an engagement mechanism mounted to the screw drive mechanism to selectively move the screw drive mechanism threads into and out of engagement with the threads of the lead screw; an engagement detector which senses the position of the engagement mechanism and provides an engagement signal representative of the engagement mechanism being in a position to cause engagement of the threads of the screw drive mechanism with the threads of the lead screw; and a processor which receives the engagement signal and controls the motor to cause the lead screw to rotate for a predetermined time period when the engagement signal indicates that the threads are not engaged. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An engagement system for engaging the threads of a lead screw with the threads of a screw drive mechanism, the screw drive mechanism operating to translate the rotational motion of the lead screw into linear motion, a plunger driver coupled to the screw drive mechanism to couple the linear motion to the plunger of a syringe, the system comprising:
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a motor coupled to the lead screw which selectively rotates the lead screw; an engagement mechanism mounted to the screw drive mechanism to selectively move the screw drive mechanism threads into and out of engagement with the threads of the lead screw; an engagement detector which senses the position of the engagement mechanism and provides an engagement signal representative of the engagement mechanism being in a position to cause engagement of the threads of the screw drive mechanism with the threads of the lead screw; a plunger detector which senses the presence of a plunger in the plunger driver and provides a plunger signal representative of the presence of the plunger; and a processor which receives the plunger signal and the engagement signal and controls the motor to cause the lead screw to rotate for a predetermined time period when the plunger signal is present and when the engagement signal indicates that the threads are not engaged. - View Dependent Claims (13, 14, 15, 16)
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17. A method for engaging the threads of a screw with the threads of a screw drive mechanism, the screw drive mechanism being of the type which moves along the screw in response to the rotation of the screw, the method comprising the steps of:
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mounting an engagement mechanism on the screw drive mechanism to selectively cause engagement of the threads of the screw drive mechanism with the threads of the lead screw; sensing the position of the engagement mechanism; providing an engagement signal representative of the position of the engagement mechanism; and selectively rotating the lead screw for a predetermined time period in response to the engagement signal indicating that the engagement mechanism is in a position at which the threads are not engaged. - View Dependent Claims (18, 19)
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Specification