Abstract
This study aims at using a disc-type ultrasonic actuator to replace the conventional sled motor used in long-seek mechanism of a CD-ROM. Experimental result demonstrates that a novel thin-disc lateral driving ultrasonic actuator can take the place of the sled motor and gear sets in optical storage tracking system without changing any control system. Data, music, and movies in a modified CD-ROM can be read out successfully and correctly with stability. The proposed disc-type ultrasonic actuator made of a piezo buzzer (diameter is 31 mm, thickness is 0.2 mm) has thin structure and low cost as compared to those of developed ultrasonic actuators. The actuator fixed by four bolts (diameter is 1.7 mm) arranged in an asymmetric rectangle (60°- 90°- 90°- 120°) along the border of a piezo buzzer denominated as “2-3-3-4 mode-shape actuator” can rotate a rotor clockwise or counter clockwise with a line speed up to 400 mm/s under 12 peak-to-peak voltage. The ratio of driving force in both directions is significantly reduced from 2.5 ~ 3 times to about 1.5 times for the proposed actuator as compared to those of “3-4-5 mode-shape actuator”. Finally, the driving circuits compensate the speed ratio in both directions. The resonance and the anti-resonance frequencies of the 2-3-3-4 mode-shape actuator are scanned first by HP 4194A impedance analyzer. Then, the vibration modes of the actuator are simulated via finite element software (ANSYS). Subsequently, the dynamic characteristics of this actuator are conducted experimentally by a test board constructed by myself. Through these measures, the resonance and the anti-resonance frequencies used in this study can be confirmed.