A new optical pickup suspension design

A new beam-type optical pickup suspension of a CD player or a CD-ROM driver is developed. Simply using the sensitivity analysis rather than sophisticated optimization tools, we show how a new good pickup suspension can be designed to satisfy certain conditions. Unlike existing suspension systems, the present suspension structure consisting of four beams has two rectangular bends in both ends of each beam. The present choice of the rectangular bend with optimally selected thickness and width of the beams provides very good low-frequency dynamic characteristics of the pickup ; the natural frequencies in two major motion directions are within the target range, and unwanted natural frequencies are made as high as possible. The development of the present suspension structure consists of two parts. The initial suspension system with the uniform width is determined based on the simplified analytic pickup model proposed in this work. Then by performing the sensitivity analysis for the resonance frequencies, based on the detailed finite element model of the initial suspension system, an optimal suspension width variation is determined. It is shown that the sensitivity analysis even without sophisticated optimization algorithms is extremely useful in actual engineering practice with a tight development schedule constraint. The strain energy is utilized to find the optimal treatment location of damping bonds which can control the quality factors at major resonances within the allowance limit. The experiments performed on the present sample model indeed yielded satisfactory results and its mass production is in progress.