Piezo actuators for millimeter-thin haptics

November 15, 2016 // By Julien Happich
Designed around multilayer piezo plates, the millimeter-thin piezo actuators from TDK's Epcos group can be driven between 1 and 1000Hz to create versatile haptic effects when embedded into the interface of consumer products.

The actuators combine a multilayered piezo plate construction with cost-effective copper inner electrodes, together with a low-profile titanium cymbals that acts as a mechanical amplifier.

Thanks to the multilayer technology the actuators can be driven with relatively low operating voltages up to 120 V. When activated, the piezo plates only expand minimally in the z axis, but due to the constant volume of the piezo effect contract simultaneously in both the x and y axes. This radial contraction is mechanically amplified by the cymbals on both sides of the plate by a factor of 15 in the z axis.

The actuator is available in two types, a 5 N type that achieves a displacement of up to 100 µm and a 20 N type that can achieve a displacement of more than 200 µm, measuring 12.7x12.7x1.6mm and 26x26x2.4mm respectively.

Compared with conventional electromagnetic solutions such as eccentric rotary motors (ERMs) and linear resonant actuators (LRAs), the piezo actuator with haptic feedback features the highest acceleration and force, the lowest insertion height and the fastest response time, all in a single component with integrated sensor functionality: Under a load of 0.1 kg, the 5 N type delivers an acceleration of 5.0 g with a rise time of 2 ms while the 20 N type features 15.0 g after just 1 ms.

Running demos at electronica ranged from camouflaged buttons with a distinct "click" feel upon touch-detection to a buzzing feel. The wide stimulation range from 1 to 1000Hz enables designers to custom develop high-definition haptic feedback profiles for use in vehicles, smartphones and tablets, household appliances and many other applications where user interfaces are key.

 

Visit TDK Corporation at www.epcos.com