Piezoelectric Actuator Drive Circuit with Duty Ratio Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing drive circuits for piezoelectric actuators in image stabilization systems lack precision and efficiency in moving objects to target positions, particularly in adjusting for camera shake and autofocus, as they rely on complex voltage signals and require extensive microcomputer control.
Innovation Solution
A drive circuit that generates square-waveform drive signals with adjustable duty states for a piezoelectric actuator, incorporating a duty storage unit, drive signal generation unit, and control unit to facilitate both coarse and fine movements by switching between different step widths, allowing precise control of the actuator's movement speed and direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a complex voltage signal is used to control the piezoelectric actuator, then the movement precision is improved, but the device complexity increases
Solution Approach 1:
The patent changes the parameter of the drive signal from complex waveforms to simple square waves with varying duty ratios. By adjusting the duty ratio parameter (e.g., 25% for fine movement, 75% for coarse movement), the system achieves different movement speeds and precision levels without requiring complex signal generation circuits, thus resolving the contradiction between movement precision and device complexity
Solution Approach 2:
The patent implements dynamic switching between different duty states (first duty state for fine movement, second duty state for coarse movement) based on the distance to the target position. The control unit dynamically selects the appropriate duty ratio to optimize both precision and speed, allowing the system to adapt its behavior to the current operational context without requiring complex hardware
2Speed
If the drive shaft moves rapidly, then the response speed is improved, but the movement precision deteriorates
Solution Approach 1:
The patent segments the movement process into two distinct phases: coarse movement phase (using second duty state with higher speed) for covering large distances, and fine movement phase (using first duty state with lower speed) for achieving precise positioning. This segmentation allows the system to combine both high speed and high precision by using the appropriate phase at the appropriate time
Solution Approach 2:
The patent performs preliminary coarse movement to quickly bring the drive shaft near the target position, then transitions to fine movement for precise positioning. This preliminary action approach allows the system to achieve both rapid response and high precision by separating the bulk movement from the fine adjustment
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
Enables rapid and precise movement of objects to target positions, improving image stabilization by efficiently compensating for camera shake and maintaining high-quality image signals through controlled displacement of lenses or imaging elements.
Implementation Method 1
Piezoelectric actuators that utilize the electrostriction effects of a piezoelectric element have conventionally been used for camera shake compensation, autofocus, and the like, for example.
Implementation Method 2
A drive circuit generates a voltage signal whereby the drive shaft has a different speed during extension and during retraction
Data Source
AI summary
In a drive circuit for a piezoelectric actuator, it is possible to move a movement object to a target position rapidly and with good precision. Parameters for two types of drive pulses (PL1, PL2) having different duty ratios are stored in a register (28). A pulse generation circuit (26) is configured so as to be able to switch, based on a parameter stored in the register (28), between (PL1) having a large displacement step width of a lens (8), and (PL2) having a small displacement step width. The lens (8) can be rapidly moved through coarse movement by (PL1), and the lens (8) can be made to approach the target position with good precision through fine movement by (PL2).