As a result of the demand for greater convenience and safety, multi-functional human-machine interfaces (HMIs) such as touchscreens and other touch-sensitive surfaces can now be found almost everywhere. Existing solutions for haptic feedback such as eccentric rotary mass (ERM) or linear resonant actuators (LRA) have a number of drawbacks. These include their relatively large dimensions, the insertion height being particularly relevant for display controllers, and a high demand for power in battery-operated devices such as smartphones or tablets. Furthermore, the frequency or the strength of the feedback are at best only variable within very narrow limits, and they do not have any sensory capabilities.
A considerably better alternative is offered by TDK’s PowerHap and PiezoHapt families of piezo-based actuators. These components are a combination of pressure-sensitive sensor and actuator in one. With the two product families, TDK offers the widest range of actuators for haptic feedback.
TDK has developed the L8060 and L3015 types specially for use in vehicle and smartphone displays. They have impressively low-profile insertion heights of just 0.35mm and 0.3mm with areas of 80x60mm (L8060) or 30x15mm (L3015). The unimorph design of the PiezoHapt is based on a flat multilayer piezo element that is connected to a vibration plate on one side and can be mounted directly underneath displays.
The actuators are designed for operating voltages of ≤24 V (L8060) or ≤12 V (L3015). Depending on the amplitude and frequency of the applied voltage, a wide range of vibration patterns can be generated with PiezoHapt. These types are especially well-suited for OLED displays.