Study On Dynamic Characteristics Of Wire Spring Type Actuator For High Density Optical Pickup

Actuator is the executing part of Optical Pickup, and its characteristics directly affect the performance of RF signal. Its frequency bandwidth determines the servo stability. With the improvement of data access rate, the dynamic characteristics of actuator need to be improved. At the mean time, the disproportion of magnetic field and assemble error enable the driving cross force and excite the disturbed motion in rolling, pitching and yawing direction, which extremely deteriorate the dynamic characteristics of actuator. Our country is inexperienced in this field, which restricts the development of the optical storage industry. Choosing the 2-D wire spring type actuator as subject and using the method of simulation coupled with experimental tools, this dissertation analyzed the influence of the design and process factors on the dynamic characteristics of actuator.This dissertation set up a magnetic field model and analyzed the driving interference under different motional conditions. At the same time, the relationship between driving interference degree and design parameters was discussed. This Study systematically set up a 3-D kinetic model. The model could describe the crossing motion in focusing, tracking and rolling direction, besides the effective motions. The model also elucidated the mechanism of crossing motion and the suppress method, so it completely described spatial motion of actuator.This study set up a finite element model by using the parametric method and performed the simulation analysis to the actuator, including static magnetic analysis, coupled field analysis, modal analysis and harmonic analysis. With experimental calibration, I got the simulation bode plot which well reflected the fact, which validated the FEA method. This model can be used for the validation of actuator design and the improvement of actuator characteristics.FEA method was used to study the dynamic characteristics at middle-low frequency and high frequency range. This dissertation analyzed rolling, pitching and yawing resonance. The two-order resonant frequency in focusing and tracking direction wereraised about 6.6% and 17.5% respectively by using the FEA method coupled with sensitivity analysis method. This improvement arrived at the basic requirement of high frequency characteristics. Eventually, the result gave us a clue of actuator design and the way of improving the dynamic characteristics.Based on the simulation method, this study systematically applied Taguchi design method and statistics method to analyze the influences of 7 kinds of process factors on performance parameters. Finally, I found out the main influence of each kind of factor and their contribution rate, thus the key factor was determined, which is very significant in large scale production.