New dimensions in performance with piezo actuators

Driven by the miniaturisation of devices and applications and the requirements for more ease of use, multifunctional touchscreens and touch surfaces have become nearly ubiquitous. While these human-machine interfaces (HMI) do feature many advantages, there is one important drawback: the haptic feedback to user actions is very limited and not strong enough.

As a result of this such HMIs are often less user-friendly and prone to errors. They can sometimes be s safety risk.

The new actuator is based multilayer piezo plates with cost-effective copper inner electrodes. Thanks to the multilayer technology the actuators can be driven with relatively low operating voltages up to 120V.

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. The new component employs cymbals on both sides of the plate as levers to amplify the contraction by a factor of 15 in the z axis. The actuator is initially available in two types, a 5N type that achieves a displacement of up to 100µm and a 20N type that can achieve a displacement of more than 200µm. Despite their compact dimensions of 12.7x12.7x1.6mm and 26x26x2.4mm, respectively, the new actuators can generate forces of up to 5N and 20N.

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 0.1kg, the 5N type delivers an acceleration of 5.0g with a rise time of 2ms while the 20N type features 15.0g after just 1ms.

Unlike conventional electromagnetic solutions the piezo actuator with haptic feedback can excite the entire stimulation range between 1-1000Hz. They have no significant frequency or amplitude limitations for customized haptic feedback to key human mechanoreceptors. In this way, the new actuator enables designers to custom develop high-definition haptic feedback profiles that users expect from cutting-edge HMIs. Applications for the piezo actuator with haptic feedback can be found, for example, in vehicles, smartphones and tablets, household appliances, ATMs and vending machines, game controllers, industrial equipment and medical devices. 

Main applications

• Vehicles, smartphones and tablets, household appliances, ATMs and vending machines, game controllers, industrial equipment and medical devices.

Main features and benefits

• Very large forces of 5N and 20N, respectively
• Large displacement of 100µm and 200µm, respectively
• Extremely low insertion height of 1.6mm and 2.4mm, respectively