Inexpensive motion control using DC motors
AssigneeHewlett-Packard Company
InventorsHuston W. Rice, Robert P. Callaway, George Barbehenn, Jason Quintana
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Abstract
Disclosed herein is a motion monitoring system for monitoring movement of a brush-type DC motor. The system includes an electrical comparator having first and second differential inputs. A current detector is connected to provide a drive current signal to the first differential input of the comparator. A low-pass filter is connected to provide an averaged drive current signal to the second differential input of the comparator. When a drive current is applied to the motor, the comparator produces a stream of binary logic-level pulses corresponding to motor movement. The pulses can be used to determine motor position and velocity.
Claims20
A motion monitoring system for monitoring movement of a brush-type DC motor that is driven by a drive current, comprising:
- a pulse detector responsive to a drive current signal and an averaged drive current signal to detect commutator-induced pulses in the drive current, wherein the commutator-induced pulses correspond to motion of the motor;
- motion determination logic configured to determine motor motion in response to the detected commutator-induced pulses in the drive current.
A motion monitoring system for monitoring movement of a brush-type DC motor that is driven by a drive current, comprising:
- an electrical comparator having first and second differential inputs;
- a current detector connected to provide a drive current signal to the first differential input of the comparator;
- a low-pass filter connected to provide an averaged drive current signal to the second differential input of the comparator;
- wherein the comparator produces a stream of binary pulses corresponding to motor movement.
A method of monitoring movement of a brush-type DC motor, comprising:
- driving the motor with an applied drive current;
- detecting pulses in the applied drive current by brush communication;
- the detecting step comprising deriving an average drive current based on the applied drive current and comparing the applied drive current to the average drive current;
- calculating motor movement based on said detected pulses.
A printer, comprising:
- a printhead;
- a moveable service station mechanism positioned to service the printhead;
- a brush-type DC motor connected to move the service station mechanism;
- control logic configured to apply a drive current tot he DC motor;
- a pulse detector connected to detect pulses in the applied drive current caused by brush commutation in the DC motor, wherein the pulse detector is responsive to the drive current and to an average drive current to produce a stream of binary pulses corresponding to motor movement;
- wherein the control logic is responsive to the stream of binary pulses to calculate motor movement.
Dependencies are inferred from the claim text.