A new technology for high density actuator arrays

A new, low cost technique for excitation and control of high density, actuator arrays has been developed. Primarily aimed at the tactile display of universal text, Braille and graphics for the Blind community, magnetic forces are utilised to actuate and hold individually addressable pins. Current tactile displays that allow Blind people to interact with the world via electronic media are expensive and due to their inherent complexity can only display the Braille language, which on average only 10% of visually impaired people in Western society are able to read. There is a need for a more flexible communication device. Using multilayer printed circuit board techniques to minimize production and assembly costs, large arrays of magnetic solenoid actuators were fabricated on a single substrate. They were electrically interconnected to allow matrix addressing of any single element in the array to reduce electronic component count. A bistable mechanism was produced using a permanent magnet layer allowing the solenoid actuator to be toggled between an 'up' state and a 'down' state. Besides being necessary for matrix addressing, this bistability gives good energy efficiency as power is only required when the system is updated and not when holding the static display. An error correction technique was developed that automatically corrected a bistable actuator if it had mistakenly moved into an incorrect position through mechanical shock. A 360 actuator demonstration unit was produced that displayed alphanumeric text, Braille or graphics in a tactile form.