Step Motor Current Control via Load Sensing Resistor
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Solution Overview
Problem
In image forming apparatuses, step motors often receive constant current regardless of load, leading to inefficiencies such as vibration, noise, and increased power consumption due to oversupply of current, and require motors with higher capacity than needed, increasing costs.
Innovation Solution
An image forming apparatus with a motor control system that senses the load of a step motor and adjusts the constant current supplied based on the measured load, using a resistor to measure current and a drive controller to determine and output the appropriate current level, ensuring optimal operation and reducing unnecessary power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If constant current is always supplied to the step motor regardless of load, then the motor can maintain steady operation, but unnecessary power consumption occurs and the motor may be oversized
Solution Approach 1:
The patent implements dynamic current adjustment by varying the constant current supplied to the step motor based on real-time load detection. The drive controller continuously monitors load conditions and adjusts the current magnitude accordingly, transitioning from static constant current to dynamic adaptive constant current, thereby optimizing power consumption while maintaining reliable operation.
Solution Approach 2:
The patent employs feedback control by detecting the load on the step motor and using this information to adjust the constant current supply. The drive controller receives load feedback and modifies the current output to match actual operational needs, creating a closed-loop system that prevents both oversupply and undersupply of current.
2Reliability
If larger current is supplied to prevent motor stepping out under increased load, then motor reliability improves, but vibration, noise, and heating increase
Solution Approach 1:
The system dynamically adjusts current magnitude based on actual load conditions, providing higher current only when load increases require it for preventing stepping out, and reducing current when load is lower, thereby minimizing vibration and noise while maintaining reliability.
Solution Approach 2:
The patent changes the current parameter adaptively based on load detection. By varying the current magnitude according to actual operational requirements, the system maintains sufficient current to prevent stepping out under high load while reducing current under lower load conditions to minimize harmful effects like vibration and noise.
3Device complexity
If constant current is supplied without load sensing, then the control system is simple, but the motor may step out under increased load or operate inefficiently
Solution Approach 1:
The patent introduces load detection feedback into the control system, allowing the drive controller to sense actual motor load and adjust current accordingly. This feedback mechanism enhances reliability and load handling capability while adding only minimal complexity to the control system.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution allows for efficient operation of step motors by matching current supply to actual load, reducing noise, vibration, and heating, while avoiding the need for oversized motors, thus enhancing performance and reducing costs.
Implementation Method 1
a driver including a resistor for measuring current that flows to a coil of the step motor
Data Source
AI summary
An image forming apparatus may include an engine portion used to perform an image forming job, a step motor configured to start the engine portion, a driver including a resistor that measures current that flows to a coil of the step motor and is configured to provide a predetermined constant current to the step motor, and a drive controller configured to measure a load level of the step motor based on a voltage value of the resistor and to control the driver to provide the constant current that corresponds to the measured load level.