Dynamic Motor Current Limiting for Transport Device Torque Control
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Solution Overview
Problem
Existing medium transport devices in recording apparatuses face issues with excessive torque applied to components due to unintended loads, leading to potential damage, especially during the initial stages of use when sliding resistance is low, and inadequate torque for operation as the load increases over time.
Innovation Solution
A medium transport device with a control section that measures the motor current and sets a limit value by adding an offset value to the measured current value, allowing for dynamic adjustment of the current supplied to the motor, thereby preventing excessive torque and ensuring sufficient torque for operation across varying loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed threshold value corresponding to assumed maximum load is used for jam detection, then the motor can be protected from excessive current during jams, but excessive torque is applied to power transmission components during unintended loads at initial usage stages
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed threshold value to a dynamic threshold value that changes based on usage history. The control section adjusts the threshold value over time to reflect the actual load characteristics of the power transmission mechanism, allowing the system to adapt to changing conditions during the lifespan of the recording apparatus
Solution Approach 2:
The patent implements parameter changes by modifying the threshold value parameter based on cumulative usage amount. The control section updates the threshold value according to the number of sheets processed or time elapsed, thereby adapting the protection characteristics to match the actual wear and load conditions of the power transmission components
2Power
If a high threshold value is set for jam detection, then the motor can handle maximum load conditions, but excessive torque damages components like gears during unintended loads at initial stages
Solution Approach 1:
The system dynamically adjusts the threshold value based on usage history, allowing high power capability to be maintained when needed while preventing excessive torque damage during initial usage stages when the threshold value is set lower
Solution Approach 2:
The control section performs preliminary action by setting an initially lower threshold value before significant wear occurs in the power transmission mechanism. This preliminary protective measure prevents excessive torque damage during the early operational phase when components are most vulnerable
3Strength
If a low threshold value is set for jam detection, then component damage is prevented during unintended loads, but the motor cannot handle maximum load conditions properly
Solution Approach 1:
The threshold value is dynamically adjusted over time, starting low to protect components during initial usage and increasing later to allow full motor performance, thereby resolving the contradiction between component protection and motor capability
Solution Approach 2:
The system implements periodic action by updating the threshold value at regular intervals based on usage amount. This periodic adjustment allows the system to alternate between protective mode (low threshold) and full-performance mode (high threshold) as appropriate for the current operational phase
Data Source
AI summary
A medium transport device includes a feeding roller that feeds a recording medium, a transport roller that transports the recording medium toward a recording head, and a transport motor which is a common driving source for the feeding roller and the transport roller. The medium transport device includes a power transmission mechanism that transmits power of the transport motor to the feeding roller, and a control section that controls a current of the transport motor. The control section measures a current value flowing through the transport motor during driving as a measured current value, and adds a predetermined offset value to the measured current value to set a second limit value as a limit value of the current supplied to the transport motor.