Control of Tiny Ultrasonic Linear Actuator Using Magneto-resistive Sensor for Camera Module

Title
Control of Tiny Ultrasonic Linear Actuator Using Magneto-resistive Sensor for Camera Module
Authors
정우석강종윤김정도윤석진
Keywords
ultrasonic actuator; magneto-resistive sensor; autofocus function
Issue Date
2010-01
Publisher
Electric power components and systems
Citation
VOL 38, NO 1, 22-32
Abstract
This article presents a control method for a tiny ultrasonic linear actuator for a camera module. The actuator is operated by a smooth impact driving method and an inertia displacement principle, and the structure of the actuator is very simple and lightweight. To precisely control the actuator, an actuator driver circuit has been developed that uses a small and inexpensive magneto-resistive sensor. The magneto-resistive sensormeasures the changing magnetic field from a magnet attached to a mobile element and has a period of 400 μm, which is scaled by 400 divisions, resulting in 1 μm resolution. A proportional-integral-derivative control is used for controlling precise position. Finally, to verify the movement characteristics of the tiny ultrasonic linear actuator using a magneto-resistive sensor, a laser Doppler vibrometer (Polytec) was used Generally, the autofocus function of a camera module needs a 10 μm resolution with a 1-mm stroke. The experimental results show that the actuator with the magneto-resistive sensor is suitable for the camera autofocus function.
URI
http://pubs.kist.re.kr/handle/201004/37473
ISSN
1532-5008
Appears in Collections:
KIST Publication > Article
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