Brushless DC Motor Rotor Phase Control for Fast Print Startup
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Solution Overview
Problem
Current image forming apparatuses face challenges in shortening the First Print Out Time (FPOT) while minimizing power consumption, particularly due to the need to estimate the initial position of the rotor in brushless DC motors, which increases energy usage and delays in starting subsequent print jobs.
Innovation Solution
The image forming apparatus includes a controller that determines the phase of a rotor in a stop state by analyzing current flowing through the motor's winding and maintains excitation of the rotor at a specific phase after a print job ends, allowing for immediate startup of the next job without re-estimating the rotor position, thereby reducing power consumption and shortening FPOT.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the rotor position is always held after a print job ends, then the initial position estimation can be omitted for subsequent jobs, but power consumption increases significantly during idle periods
Solution Approach 1:
The controller performs periodic determination of rotor phase at specific intervals (when a print job ends and a predetermined period elapses), rather than continuously holding the rotor. This periodic action allows the system to switch between power-saving mode (rotor not held) and performance mode (rotor held) based on operational needs, resolving the contradiction between reducing FPOT and minimizing power consumption.
2Use of energy by moving object
If the rotor is not held after a print job ends, then power consumption is reduced, but the initial position estimation must be performed for the next job, increasing FPOT
Solution Approach 1:
The controller determines the rotor phase in advance (when the predetermined period elapses after a print job ends) before the next print job starts. This preliminary action ensures that when the next job begins, the rotor position information is already available, allowing immediate startup without position estimation, thus reducing FPOT while avoiding continuous power consumption.
3Measurement precision
If initial position estimation is performed for every print job, then accurate rotor position is ensured, but time is lost during each job startup
Solution Approach 1:
The rotor phase is determined in advance during idle periods (when a predetermined period elapses after a print job ends), so that when the next print job starts, the position information is already available. This eliminates the need for time-consuming position estimation at job startup, reducing startup time while maintaining position accuracy.
Solution Approach 2:
The system uses the motor's own winding characteristics to determine rotor phase by analyzing current flow during coasting operation, without requiring external position sensors or complex estimation algorithms. This self-service approach maintains accurate rotor position information using simple, fast measurements, reducing startup time while ensuring position accuracy.
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 approach enables a reduction in power consumption and a faster FPOT by eliminating the need for initial position estimation in subsequent print jobs, improving operational efficiency and energy management.
Implementation Method 1
determines a phase of the rotor having been in the stop state based on the current flowing through the winding of the motor
Implementation Method 2
controlling the current to be supplied to the winding in such a manner that the rotor having been in the stop state rotates, based on the phase determined by the initial operation
Implementation Method 3
the controller controls the current to be supplied to the winding in such a manner that the rotor is held at a first phase
Data Source
AI summary
An image forming apparatus includes a stacking portion, a pickup roller, a motor, an image forming unit, and a controller. Upon receiving an instruction for starting a first image forming job, the controller performs an initial operation of supplying current to a motor winding of the motor in a stop state and determining a phase of the rotor based on the flowing current. Based on the determined phase, the controller supplies current to rotate the rotor from its stop state and holds the rotor at a first phase when the first job ends. Upon receiving start instructions for a second image forming job within a period until a predetermined time elapses from when the rotor is held at the first phase, the controller rotates the rotor without performing the initial operation. The controller stops supplying current to the winding if no instructions are not received for starting the second job.