Solid State Joint Actuator for a Vibro Tactile Line Display

A new actuator concept for a vibro tactile line display based on solid-state joints is introduced. By using piezo stacks in conjunction with the solid-state joints, large deformations with high forces can be achieved. For this purpose, a special cold-rolled spring strip steel is used for the Solid-State Joint Transmitter (SSJT). Due to the layer-by-layer arrangement of the Solid-State Joint Actuators (SSJA), a finger contact area of 9.8 mm x 5.9 mm is achieved with five SSJA. The development of the SSJA was carried out with FEM simulations in order to identify and if possible eliminate areas of critical stress. The finger load on the SSJA is already taken into account during development using a spring-damper model. From the small signal behaviour of the SSJA, a spring-damper model is created and suggested for later control. By means of performance tests, it is shown that large deflections are achieved over a wide frequency range. For this purpose, the SSJA is measured under real operating conditions (when a test person puts his finger on the display).