Design of a slim-type optical pick-up actuator using PMN-PT bimorphs

Abstract

In this paper, a new optical pick-up actuator is proposed using PMN-PT (lead magnesium niobate-lead titanate) bimorphs for slim and small form factor optical disk drives. We suggest a novel structure enabling both tracking and focusing motions by changing the moving directions of the two parallel bimorphs. A cymbal-type flextensional structure is used as a displacement amplifier in order to meet the stroke requirement for optical pick-up actuators. We have performed the theoretical analyses for the bimorph actuator and displacement amplifier to predict the resultant force and displacement. The proposed actuator based on PMN-PT bimorphs and displacement amplifier has been manufactured, and the experimental results are compared to the analytical predictions. Experimental results agree well with the analytical predictions, showing that the cymbal structure amplifies the displacement twice and the focusing stroke is 52 μm at 10 V.

Pb(Mg1/3Nb2/3)O3–PbTiO3(PMN-PT) Material for Actuator Applications

“…in the literature is the bending type [34,37,53]. Kim et al [37] showed that the tip displacement of the bendingtype PMN-PT single-crystal actuators can be several times larger than ones made from PZT ceramic actuators of the same design.…”

“…field. For some applications, the 1.5 kV/cm is a large input value, for example, in mobile devices where a voltage of only 10 V is normally used [34]. In any case, the PMN-PT material can be appropriate for bending actuators in applications operating at higher voltages, where the linearity of the response to the applied el.…”

Relationship between crystal structure and ferroelectric properties in Bi_0.5−0.5<i>_x</i>Na_0.5−0.5<i>_x</i>Sr<i>_x</i>Ti₁₋<i>_x</i>Zr<i>_x</i>O₃ ceramics

“…1), 2) On the other hand, worldwide efforts to eliminate the use of hazardous substances like lead from electronics and their wastes indicate difficulty in the use of piezoelectric ceramics.…”

Crystal structure and ferroelectric properties of Bi_0.5Na_0.5TiO₃-modified Bi_0.5+0.5<i>_x</i>Na_0.5−0.5<i>_x</i>Ti₁₋<i>_x</i>Mn_0.75<i>_x</i>Mo_0.25<i>_x</i>O<

“…1), 2) However, the strong toxicity of lead oxide and its high evaporation rate during sintering processes have led to critical concerns about environmental pollution. Therefore, it is necessary to develop lead-free multi-component ferroelectric ceramics with properties that are comparable to those of lead-containing ceramics.…”