Alps Develops Miniature Piezoelectric Actuator

Alps Electric has completed development of the ATSA Series miniature piezoelectric actuator used in mechanisms requiring linear movement, such as in mobile phones and other handheld devices as well as in the sensitive drives essential to precision devices.

Today's mobile phones and precision devices are well known for offering a sophisticated array of functions, with the trend being toward ever smaller and thinner products. Consequently, the parts used in these devices are also becoming smaller, yet at the same time high performance is in demand.

This is evidenced by the delicate and precise adjustments - in increments of 10 micrometers (µm. 10µm=0.01mm) - needed to correct the spherical aberration that occurs when the collimator lens of a Blu-ray optical pickup is commanded to execute linear movement.

Traditionally, an electromagnetic motor has been used for the linear movement of the collimator lens in this type of optical pickup, as well as for the zoom and auto focus functions of mobile phone cameras and digital cameras. However, miniaturization of these motors is approaching its limits, and actuators that offer high performance in a small size have become essential.

The ATSA Series has realized the industry's smallest piezoelectric actuator, with main body dimensions of 1.8mm x 1.8mm x 6.0mm (wide x deep x long, excluding the shaft portion). This product employs a structure in which four piezoelectric elements envelop a central screw shaft, with the drive directly rotating the shaft by utilizing the properties of these elements - namely their ability to change shape as voltage is applied. It thus becomes possible to reduce the number of parts and miniaturize parts in the assembly, in comparison with actuators with electromagnetic motors, successfully enabling a significant reduction in overall actuator size.

This product has been developed under an engineering license agreement with U.S.-based New Scale Technologies, Inc. For commercialization and mass production, Alps Electric's microfabrication technology will be employed to manufacture the shaft to 1.1mm, the diameter of a pen tip.

The characteristics of the ATSA Series include a push force of more than 0.169N and a drive speed of more than 5mm/second, in addition to being the industry's smallest actuator to sufficiently exert the required drive force for collimator lens adjustment, and linear lens movement for camera zoom and auto focus functions. In addition, the ATSA Series enables a long drive distance, being capable of moving a distance of 6mm with a shaft length of 12mm.

Furthermore, no other parts or assemblies are required to maintain the drive position. Because the screw holds its position when power is turned off, this contributes to the low power consumption of other electronic components in the unit.

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