Stepping Motor Drive Control for Optical Pickup Positioning Stability
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Solution Overview
Problem
Optical disk devices using stepping motors face operational instability due to temperature-related mechanical load changes, leading to out-of-step phenomena and reduced performance, especially in broad temperature environments common in onboard applications.
Innovation Solution
Incorporating a temperature sensing unit and drive controlling unit that adjust the driving current and supply time width of the stepping motor in response to ambient temperature, allowing for appropriate torque and stable feeding operations across varying temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the stepping motor is driven with continuous current supply for microstep drive, then the feeding operation precision is improved, but the power consumption increases and heat generation increases
Solution Approach 1:
The patent applies periodic action by switching between continuous current supply (for precision positioning) and intermittent current supply (for power saving). The microstep drive uses continuous current to achieve fine feeding precision of several tens of micrometers, while the intermittent drive reduces power consumption during periods when high precision is not required. This periodic switching resolves the contradiction between precision and power consumption.
2Manufacturing precision
If the stepping motor is driven with continuous current supply for microstep drive, then the feeding operation precision is improved, but the heat generation increases shortening part life
Solution Approach 1:
The patent uses periodic action to alternate between continuous current supply (for precision) and intermittent current supply (for heat reduction). By switching to intermittent drive when full precision is not needed, the system reduces heat generation that would otherwise shorten the life of motor parts and other components.
3Measurement precision
If the stepping motor is used for optical pickup feeding, then the positioning accuracy is improved, but the operational stability deteriorates in broad temperature environments
Solution Approach 1:
The patent applies dynamics by making the drive mode flexible and adaptable to temperature conditions. The system dynamically switches between microstep drive (for precision) and intermittent drive (for stability in temperature variations). The temperature sensing unit detects ambient temperature, and the drive controlling unit adjusts the drive mode accordingly, resolving the contradiction between positioning accuracy and operational stability in broad temperature environments.
Solution Approach 2:
The patent uses feedback through the temperature sensing unit that continuously monitors ambient temperature. Based on this temperature feedback, the drive controlling unit adjusts the stepping motor drive mode between microstep and intermittent drive, ensuring operational stability while maintaining positioning accuracy when conditions permit.
4Manufacturing precision
If the microstep drive is used for fine feed control, then the feeding precision is improved, but the drive complexity increases
Solution Approach 1:
The patent applies dynamics by implementing a drive system that can adapt between microstep mode (for precision) and intermittent mode (for simplicity). The temperature sensing unit and drive controlling unit create a dynamic system that selects the appropriate drive mode based on temperature conditions, reducing overall system complexity while maintaining precision when needed.
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 stabilizes the feeding operation of the optical pickup even in broad temperature environments, preventing defective operations and enhancing the reliability of optical disk devices, particularly in onboard equipment.
Implementation Method 1
a temperature sensing unit for sensing an ambient temperature of the optical pickup
Implementation Method 2
a stepping motor for moving the optical pickup in a radial direction of the optical disk
Data Source
AI summary
In an optical pickup driving mechanism using a stepping motor, a feeding operation of an optical pickup can be stabilized even in a broad operating temperature environment. In executing an optical axis correction feeding operation in response to an amount of lens shift of an objective lens of an optical pickup, a stepping motor controlling portion drives a stepping motor in a microstep drive mode to move a base of the optical pickup in a radial direction of an optical disk. At this time, a temperature sensor senses an in-equipment temperature, and a driving current supply time deciding portion sets a supply time width of a pulse driving current whose envelope is like a sinusoidal wave to a supply time width as a fixed value, which is longer than that at an ordinary time, or a supply time width, which is multiplied by a coefficient corresponding to the in-equipment temperature, to increase a current supply time of the driving current when the sensed in-equipment temperature is equal to or lower than a predetermined temperature.