Mechanism design of the flapper actuator in Chinese Braille display

Abstract

This report presents the mechanism design of flapper type actuator used in a Chinese Braille display called Golden Braille display (GBD) in Taiwan. An actuator is the most important part to manipulate the Braille dot in Braille display. The proposed flapper actuator is designed with numerical analysis, including contact mechanics, heat transfer, and electromagnetics to ensure the feasibility and durability of the design. Experiments are conducted to verify the simulation results of numerical analysis. The optimal results indicate that the flapper should operate at 6V with a 330Ω enameled coil. The thrust force of Braille dot reaches 15.9gf and the temperature rising of flapper is well restrained at 42.9°C when the cooling blowers are equipped in GBD. Mechanics analysis shows that even when the flapper's trust force reaches 20gf to interact with finger's pressing force, the absolutely maximum stress of flapper's armature is only 1.16E−1% of its yield stress and the Braille dot of Braille pin is only 1.19E−2% of its yield stress. The negligible stress loading indicates the structure of flapper is sufficiently robust. Our investigation also shows that GBD is a durable and economically viable alternative of Braille display.