Optical Element Drive Layout to Protect Lens Position Sensing
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Solution Overview
Problem
In small-sized, thin camera-mounted devices, the use of ultrasound motors for lens driving requires high drive voltages, which can lead to reduced accuracy in lens position detection due to leakage flux from inductors used to increase input voltage, affecting the magnetic sensor's detection accuracy.
Innovation Solution
The optical element driving device includes a piezoelectric element-driven holding part, an inductor to increase voltage, and a position sensor that detects magnetic forces to determine the relative position, with the inductor and position sensor disposed in separate regions to minimize the impact of leakage flux.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an inductor is used to increase the input voltage to the piezoelectric element, then the drive voltage requirement is met, but the leakage flux from the inductor reduces the detection accuracy of the magnetic sensor
Solution Approach 1:
The device is divided into distinct functional regions: a first region housing the inductor and its coil, and a second region housing the magnetic sensor. This spatial segmentation isolates the magnetic sensor from the leakage flux generated by the inductor coil, allowing the inductor to provide necessary voltage boosting without compromising sensor detection accuracy.
2Volume of moving object
If the coil of the inductor is positioned close to the magnetic sensor, then the device size is reduced, but the leakage flux from the coil reduces the detection accuracy
Solution Approach 1:
Instead of positioning components along a single axis, the patent utilizes three-dimensional spatial arrangement by dividing the device into multiple regions at different positions. The inductor and magnetic sensor are placed in separate regions that are spatially distributed, effectively utilizing available volume while maintaining adequate separation between the coil and sensor to minimize magnetic interference.
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 configuration prevents the reduction in accuracy of lens position detection, ensuring precise focusing and image capture in camera modules and camera-mounted devices.
Implementation Method 1
a driving part including a piezoelectric element configured to drive the holding part
Implementation Method 2
a position sensor configured to acquire a relative position of the holding part and the housing part in the optical path direction by detecting a magnetic force of a magnet
Implementation Method 3
the input voltage is increased by using an inductor, and supplied to the ultrasound motor
Data Source
AI summary
An optical element driving device includes: a holding part configured to hold an optical element; a housing part configured to house the holding part such that the holding part is movable in an optical path direction of the optical element; a driving part including a piezoelectric element configured to drive the holding part; an inductor configured to increase an input voltage to the piezoelectric element; and a position sensor configured to acquire a relative position of the holding part and the housing part in the optical path direction by detecting a magnetic force of a magnet. In regions defined by dividing the holding part and the housing part into equal quarters around an optical axis, the driving part and the position sensor are disposed in a same region, and the inductor is disposed in a region different from the same region.