Piezoelectric Drive Device Lens Displacement Control
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Solution Overview
Problem
Existing drive devices for autofocus and zoom functions in camera modules face challenges in accurately controlling the displacement of lenses due to resonance issues caused by coupling the piezoelectric element with a stationary member, leading to difficulties in setting the drive frequency and maintaining product yield.
Innovation Solution
A drive device design where the piezoelectric element and drive shaft are positioned to move in synchronization with a movable object relative to a stationary member, with the drive shaft being slidable and the piezoelectric element spaced from the stationary member, allowing for easier frequency setting without considering resonance in the stationary member, using a lightweight and rigid material for the drive shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the piezoelectric element is coupled to the stationary member, then the drive device structure is stable, but resonance occurs in the stationary member causing difficulty in controlling lens displacement
Solution Approach 1:
The drive device is segmented into independent functional modules: the piezoelectric element, drive shaft, and lens holder are separated from the stationary member (camera module housing). This segmentation prevents resonance transmission to the stationary member while maintaining structural stability through dedicated support structures.
Solution Approach 2:
The piezoelectric element and drive shaft assembly is extracted from the stationary member structure, allowing the resonant components to be isolated. The drive shaft is supported by bearings mounted on the stationary member rather than being directly coupled, extracting the resonant system from the housing structure.
2Speed
If the drive frequency is set within the resonance frequency range, then the lens displacement speed is improved, but accurate control becomes difficult and product yield decreases
Solution Approach 1:
The resonance phenomenon is converted from a harmful factor into a beneficial one by designing the drive shaft and piezoelectric element assembly to resonate at specific frequencies. This resonance amplifies the displacement effect, enabling high-speed lens movement while maintaining control through precise frequency selection and waveform control.
Solution Approach 2:
The drive frequency and voltage waveform parameters are dynamically adjusted to optimize performance. By changing the frequency parameter to match the resonant frequency of the drive assembly and adjusting voltage waveform characteristics, the system achieves both high-speed displacement and accurate control.
3Reliability
If the piezoelectric element is not fastened to the stationary member, then resonance in the stationary member is reduced, but the drive shaft stability is compromised
Solution Approach 1:
Bearings serve as intermediary components between the drive shaft and the stationary member. These bearings provide stable rotational support and positioning for the drive shaft while isolating it from the stationary member housing, preventing resonance transmission. The intermediary bearing structure maintains drive shaft stability without direct coupling to the housing.
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 design reduces the obligation to consider resonance in the stationary member, enabling more precise control of the drive frequency and improving the yield of camera modules by stabilizing the displacement of lenses across various frequency ranges.
Implementation Method 1
a piezoelectric element that expands and contracts according to a drive voltage
Data Source
AI summary
A drive device in which the frequency of a drive waveform applied to a piezoelectric element is easily settable with less obligation to consider resonance in a stationary member. The device includes a piezo element that expands and contracts according to a drive voltage, a transmission shaft that receives vibration produced by the piezo element, a stationary member that holds the transmission shaft in a slidable state along the longitudinal direction of the transmission shaft, and a lens holder that is displaced together with the piezo element and transmission shaft relative to the stationary member according to drive of the piezo element. The piezo element and the transmission shaft move in the moving direction of the lens holder in synchronization with the lens holder according to drive of the piezo element in the state where the piezo element is spaced from the stationary member. By employing this structure, the frequency of the drive waveform applied to the piezo element can be set easily without considering resonance in the stationary member.