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Algorithm for a Stepper Controlled Ejector Cam

IP.com Disclosure Number: IPCOM000236945D
Publication Date: 2014-May-22
Document File: 1 page(s) / 26K

Publishing Venue

The IP.com Prior Art Database

Abstract

This idea proposes an algorithm for a stepper motor controller that will reduce the likelihood of stepper motor stall when accelerating a load, in cases where the load/torque acting on the stepper is position dependent. An example of where this idea could be used is a stepper motor which operates a cam to move a set ejector arms in a compiler for a stacking subsystem in a cut sheet printer. The algorithm includes a pre-eject movement in order to reduce the distance to the load. This allows contact with the load to occur at lower speed during the actual eject movement, thus reducing the likelihood that the motor will stall.

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Algorithm for a Stepper Controlled Ejector Cam

This idea proposes an algorithm for a stepper motor controller that will reduce the likelihood of stepper motor stall when accelerating a load, in cases where the load/torque acting on the stepper is position dependent. An example of where this idea could be used is a stepper motor which operates a cam to move a set ejector arms in a compiler for a stacking subsystem in a cut sheet printer. The algorithm includes a pre-eject movement in order to reduce the distance to the load. This allows contact with the load to occur at lower speed during the actual eject movement, thus reducing the likelihood that the motor will stall.

A stapler module in a cut sheet printer might use a stepper based cam to move ejector arms to push sheets out of the compiling area and then retract the arms back in.  When operating at the desired print speed there is very little time between the software sending a command down to start ejecting the set and when that eject operation needs to be finished so that the next set can begin compiling. This makes a fast ejector profile a necessity. While running this fast eject profile, the ejector stepper motor can potentially stall upon making contact with the set because the available torque is lower at the higher speed. One alternative to solve this problem would be to operate at a lower overall rate so the eject profile speed could be reduced, resulting in higher torque.

In the example set compiler design, the ejector arm is returned to the home position in between cycles. The home position leaves the ejector arm in a position where when the profile is executed, the ejector arm needs to travel sev...