Image Forming Motor Sequencing to Limit Peak Load Current
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Solution Overview
Problem
The use of a sensorless motor in an image forming apparatus leads to an excessively large load current maximum value when a preparation operation is performed prior to starting image formation, increasing the cost of the circuitry due to overlapping execution periods of position detection and rotational operations.
Innovation Solution
The control unit is configured to control the first and second motors such that the execution timing of position detection or retraction operations for the sensorless motor and the start of rotational driving of the second motor do not overlap, thereby managing the load current supply to prevent excessive values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a preparation operation (temperature adjustment of fixing unit) is performed prior to starting image formation to shorten FPOT, then the First Print Out Time is reduced, but the maximum load current value becomes excessively large due to overlapping execution periods
Solution Approach 1:
The patent applies preliminary action by performing the position detection operation of the sensorless motor before starting the preparation operation (temperature adjustment of the fixing unit). This sequencing ensures that the high-current position detection phase completes before the fixing motor begins its heating cycle, preventing overlapping current peaks and avoiding excessively large maximum load current values while still achieving short FPOT through advance temperature preparation.
2Productivity
If the position detection operation and rotational driving operation are performed simultaneously to reduce total operation time, then the productivity is improved, but the maximum load current value becomes excessively large
Solution Approach 1:
The patent applies periodic action by dividing the motor operation into distinct sequential phases: first the position detection operation (high current, short duration), then the rotational driving operation (lower current, longer duration). This periodic sequencing eliminates simultaneous operation of both high-current processes, preventing excessive maximum load current while maintaining overall productivity through efficient use of the low voltage power supply capacity over time.
Data Source
AI summary
An image forming apparatus includes a first motor that drives an image forming unit and that includes a motor of a type that lacks a sensor for detecting a rotational position of a rotor of the first motor, and a second motor that drives a fixing unit. A control unit causes rotational driving of the second motor to start after completion of a first operation for detecting a rotational position of the first motor or a second operation for causing the rotor to rotate to a predetermined rotational position, such that an execution timing of the first operation or the second operation and a timing at which rotational driving of the second motor is started do not overlap.