Alignment of Image Sensor using Piezoelectric Crystals

Sammanfattning: The use of piezoelectric crystals as a way to achieve automatic alignment of an image sensor in a camera was investigated in collaboration with Axis Communications AB. Piezoelectric crystals can be created into different configurations, piezoelectric stacks being one of the simpler ones. By attaching three piezoelectric stacks behind an image sensor and applying voltage to the stacks, they expand and the length between the sensor and the lens component is altered thus a change in the amount of focus will occur. Tests conducted in both a light controlled environment provided by Axis as well as in scenes similar to those of a user, showed promising results of focus correction with the use of a lens displacement of 41 μm. Furthermore, the unique quality of tilting of the image sensor was investigated. An auto focus algorithm was used to automatically align the center and corners of the image. Moreover, deliberate tilting was employed to adjust the focus placement in the image. Findings suggest that piezoelectric crystals are an effective method for achieving automatic alignment and controllable focus in cameras, with promising results in both controlled and real-world environments. Overall, this study demonstrates the potential of using piezoelectric crystals for automatic alignment and controllable tilt in cameras. Although further investigations are needed before the solution can be used in a product, our findings provide a foundation for future research in this area.