Stepper Motor Current Detection Circuit for Noise and Heat Control
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Solution Overview
Problem
Existing image forming apparatuses face challenges in detecting the effective value of motor current in stepping motors, leading to potential noise emission and abnormal heat radiation, which can be addressed by implementing a simple and cost-effective circuit configuration for current detection.
Innovation Solution
A motor drive device with a detection circuit that includes a current-voltage conversion circuit and an amplifier circuit to detect the induction current in a spiral coil pattern, allowing for control of the motor current based on detection signals to prevent noise and heat issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current detection IC is used to detect the effective value of motor current, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the conventional current detection IC (electronic measurement system) with a magnetic field-based detection system using a coil pattern and detection circuit. The coil pattern detects current through electromagnetic induction, converting electrical current measurement into a magnetic field detection problem, thereby simplifying the overall circuit configuration while maintaining detection capability
Solution Approach 2:
The patent creates a simplified detection model by using a coil pattern that generates an induction current proportional to the motor current. This indirect detection method copies the current information through magnetic field coupling, allowing detection without direct electrical contact or complex IC circuits
2Productivity
If chopper control is used to drive the stepping motor, then productivity is improved, but object-generated harmful factors worsen due to noise and heat radiation
Solution Approach 1:
The patent implements a feedback control mechanism where the detection circuit continuously monitors the motor current through the coil pattern and provides detection signals to the control portion. The control portion adjusts the chopper control parameters based on this feedback, optimizing motor drive while suppressing noise and heat generation by adapting to actual current conditions
Solution Approach 2:
The patent dynamically changes control parameters in the chopper control based on detection signals from the coil pattern. By adjusting switching frequency, duty cycle, or current limits in response to real-time detection data, the system maintains high productivity while minimizing noise and heat radiation through optimized drive parameters
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
The solution effectively detects the motor current, reducing noise and heat generation in stepping motors, thereby enhancing the operational stability and efficiency of image forming apparatuses.
Implementation Method 1
The detection circuit detects a magnitude of an induction current that flows in the coil pattern
Data Source
AI summary
A motor drive device includes a substrate, a motor drive portion, a feed pattern, a coil pattern, and a detection circuit. The feed pattern is formed on a first surface of the substrate. The coil pattern is formed on a second surface of the substrate and includes an overlapping portion formed in a region overlapping with the feed pattern and an adjacent portion formed in a region adjacent to the feed pattern. The detection circuit detects a magnitude of an induction current that flows in the coil pattern and outputs a detection signal. The detection circuit includes a current-voltage conversion circuit and an amplifier circuit.