US Patent 10581343 Electret-based electrostatic haptic actuator

An electret-based haptic actuator is presented. The actuator having an electret layer, an electrically conductive layer, an electrically insulative layer, a plurality of spacers, and a signal generating circuit. The electret layer having a built-in voltage along a thickness dimension of the electret layer. The electrically insulative layer being disposed between the electret layer and the electrically conductive layer. The plurality of spacers being disposed between the electret layer and the electrically conductive layer. The signal generating circuit being electrically connected to the electrically conductive layer and not electrically connected to the electret layer. The signal generating circuit being configured to apply an oscillating drive signal to the electrically conductive layer to generate a vibrotactile haptic effect.