Design and Evaluation of an Electromagnetic Bounce-type Refreshable Braille Display

To help the blind or visually impaired (BVI) read digitally conveniently and at low cost, we propose a bounce-type actuator driven by electromagnetic force, and based on this, a refreshable Braille display (RBD) which can display both Braille and tactile graphic information is manufactured. The internal components of the bounce-type actuator include an electromagnet and two permanent magnets placed in a stepped manner. By passing current in different directions to the coil, the electromagnet can bounce up and down between the two permanent magnets under the action of magnetic force, thereby achieving changes in the raised state of the Braille dot. The permanent magnets placed in staggered positions have an attractive and supportive effect on the electromagnet, so the raised Braille dot can be locked in a specific position when the electromagnet is not powered on and provide a large latching force. In this paper, the force analysis and finite element simulation of the actuator actuation condition of the Braille dot actuator are carried out, and the refresh rate is measured experimentally to be about 16 Hz. Meanwhile, the overall refresh rate of the prototype can be up to 2.7 Hz. Benefiting from the full-latching structure, the RBD proposed in this paper is characterized by a large latching force, a high refresh rate, and an easy scalability. It also has the advantages of low cost, low energy consumption, reliability, and durability, providing an easy-to-promote tool for BVI to read digital information.