Stepping Motor Control Circuit for Optical Disc Drive Power Reduction
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Solution Overview
Problem
There is a demand for reducing power consumption in optical disc devices and their motor control circuits, particularly in controlling the movement of optical pickup units within optical disc devices.
Innovation Solution
A motor control circuit and method that selectively supplies a stepping motor with reduced drive currents by varying the ratio of ON and OFF periods, using a current setting signal and a current reducing signal to optimize current usage based on operational requirements during tracking servo mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the motor is continuously supplied with full drive current to maintain ready state, then the motor responds quickly to movement commands, but current consumption increases
Solution Approach 1:
The patent applies dynamics by transitioning the motor from a static full-current state to a dynamic current modulation state. The motor current is dynamically adjusted between full drive current (during movement) and reduced current (during idle tracking), allowing the system to adapt power consumption to actual operational needs while maintaining readiness.
Solution Approach 2:
The patent implements periodic action through pulse-width modulation (PWM) of the motor current. The current is supplied in periodic pulses with variable duty cycles, where the ON period provides full current for movement and the OFF period reduces current consumption during idle tracking, achieving energy savings while maintaining motor responsiveness.
2Use of energy by moving object
If the motor current is reduced during idle periods, then power consumption decreases, but the motor may not respond quickly when movement is needed
Solution Approach 1:
The patent applies preliminary action by maintaining the motor in a reduced-current ready state rather than completely shutting off power. The motor remains energized at a lower current level that preserves sufficient magnetic field strength for quick response, eliminating startup delays while reducing power consumption during idle tracking periods.
Solution Approach 2:
The system dynamically switches between current levels based on operational state. When tracking is stable and no movement is detected, reduced current is applied. When movement commands are issued or tracking error exceeds thresholds, full current is immediately restored, ensuring reliable responsiveness while optimizing power usage.
3Measurement precision
If full drive current is supplied continuously to maintain tracking precision, then the optical pickup responds accurately to positioning requirements, but current consumption increases
Solution Approach 1:
The patent applies local quality by differentiating current supply based on operational phases. Full current is supplied locally during movement phases when positioning precision is critical, while reduced current is applied during stable tracking phases where the optical pickup maintains position without active adjustment, optimizing the balance between precision and power consumption.
Solution Approach 2:
The patent uses partial action by supplying reduced current during idle tracking periods when full current capability is not needed. The reduced current maintains sufficient magnetic field strength for tracking precision while avoiding the excessive power consumption of continuous full-current supply, applying only the necessary amount of current for each operational phase.
Data Source
AI summary
A motor control circuit for reducing current consumption. A stepping motor control circuit includes an A/B phase current setting signal generation circuit for generating an A/B phase current signal setting signals provided to a stepping motor driver to supply a stepping motor with a predetermined amount of drive current. Based on a switch signal, first and second switches selectively output an A/B phase current setting signal and an A/B phase reference signal, for reducing the drive current of the stepping motor more than the A/B phase current setting signal. An intermittent drive control circuit generates the switch signal. The stepping motor control circuit provides the motor driver with the A/B phase reference signal in accordance with the switch signal.