Two-dimensional Braille readers based on electrorheological fluid valves controlled by electric field

Holes filled with electrorheological fluids (ERF) are used to form the Braille symbols or a relief in array manipulators. Matrix of holes is made from the fabric-based copper laminate. Voltage applied to upper and lower coppered surfaces of the plate, creates electric field, which controls ERF viscosity. Three methods to form a relief are investigated: (a) using an elastic membrane, covering the holes; (b) dielectric pins moving in the holes; and (c) metallic pins moving in the holes. Electric field in a hole of the matrix is calculated as the electric field in a hole of the plane capacitor. When voltage upon electrodes is kept uniform, the mean electric field in the electrorheological fluid with metallic pins becomes 1.7, with dielectric pins mean electric field being 1.25 times stronger than in the electrotheological fluid with the membrane. In the case of metallic pins, the mean electric field near the electrodes is considerably stronger than in the case of dielectric pins. In the points situated not further than 0.25 of the hole height in the direction of the hole axis, the mean electric field is 3 times stronger than in the hole without the pin. The controlling voltage can be decreased using multilayer copper laminate valves, composed of some fabric-based plates in the opposite directions of the electric field in the neighboring plates. (c) 2007 Elsevier Ltd. All rights reserved.