Patent GB-1485698-A (GB)
Title: Device for the representation of at least one touchable shape outline or character
IPC: G09B21/00
Filed: 1975-02-14
Abstract: 1485698 Apparatus for producing touchable images H-P LINDENMULLER and K P SCHONHERR 14 Feb 1975 [16 Feb 1974] 6448/75 Heading G5G Apparatus for producing a touchable image, e.g. a shape, outline or character such as a Braille character, comprises an array of key buttons 10, Fig. 1, which can be individually raised and lowered relative to a reference plane 21 to produce the touchable image, a plurality of operating means each for raising and lowering the respective key button, each operating means comprising electromagnetic means energizable to selectively raise and lower the respective key button and mechanical locking means arranged to resist depression of the respective key button on de-energization of the electromagnetic means. The key-buttons 10 are raised by means of energization of the cores 26 of respective first electromagnets, each key button 10 being secured to a respective magnet core 12. Raising of a key button 10 causes a respective magnetic ball or cylindrical roller 28 to move to the right in a compartment 30, and allows a magnet core 36 of a respective unenergized second electromagnet to move upwards under the influence of a spring 50, thereby locking the key button 10 in its raised position. Lowering of a key button 10 is achieved by energizing the second electromagnet, thereby causing movement of ball or roller 28 to the left and lowering of magnet core 12 under the influence of a spring 24. Movement of the ball or roller 28 in each direction is mechanically assisted by means of bevelled bearing surfaces 46, 48 which act in conjunction with the restoring springs 24, 50. A plurality of balls or rollers 28 may be provided, Figs. 5a-5d (not shown), in order that each key button 10 can be locked in a variety of raised positions, when the apparatus is required to represent "grey" values of an image, in distinction to the case where "white" represents the lowered position of a key button and "black" represents the raised position. In a second embodiment, a key button 110, Fig. 2a, is integral with a magnet core 112 of the first electromagnet, the magnet core 112 having thereon quadrant-shaped respectively magnetic and non-magnetic projections 152, 154, Fig. 4a, the magnet core 112 being slidable and rotatable in a guide 114 and co-operating with generally similar respectively magnetic and non-magnetic projections 156, 158 of an axially-aligned magnet core 136 of the second stationary electromagnet. In order to raise a key-button, the first and the second electromagnets are so energized that like poles are created in projections 152, 156. Axial and tangential forces are thereby exerted on magnet core 112, causing lifting of the core 112 and rotation thereof until projection 154 abuts a step 159 incorporated in projection 158, thereby locking the key button against depression. Lowering of a key button is achieved by so energizing the first and the second electromagnets that unlike poles are created in projections 152, 156, the magnet cores thereby being attracted to one another and the above raising process reversed. The second electromagnet in this embodiment may be replaced by a permanent magnet.