Nokia has previously talked about their haptikos tactile touchscreen that has two small piezo-sensor pads under the screen and creates a 0.1mm movement in the screen. But few details were revealed about the mechanism behind the system. A recent patent filed by Nokia for the technology brings more details about how this touchscreen works. According to Nokia the main idea behind the haptikos system is to create variable and controllable user perceived surface roughness or friction to generate a feedback when the user touch’s the screen. To achieve this Nokia uses protuberances filled with fluid and made of elongated elements that extend parallel to the touchscreen. Along these protuberances there are piezoelectric actuating members that protrude into them as voltage is applied. The resulting pressure raises the elastic surface making the touchscreen surface rough. In normal state, when no current is applied the surface of the touchscreen is smooth.
Nokia says that larger number of actuators can be place on the touchscreen and each actuator can be controlled independently. Creating a dynamically controlled surface through out the touchscreen. The actuators can be moved back further then the default position to create a negative pressure on the tactile feedback compartments thus creating the feel of the surface bulging in as if you have pressed a button. There is no word on whether this technology will be ready for implementation in the touchscreen phone that Nokia will release some time late this year or early next year.