Patent GB-744967-A (GB)
Title: Artificial vision system and apparatus, particularly for the blind
IPC: G09B21/00
Filed: 1953-12-30
Abstract: 744,967. Photo-electric apparatus for enabling the blind to read. SAUDEMONT DE ST. QUENTIN, P. Dec. 30, 1953 [Dec. 30, 1952], No. 36179/53. Class 40 (3). An apparatus, particularly for use by the blind, for enabling an object to be perceived by touch at a point removed from the object, comprises means for forming an image of the object, and a plurality of devices in a pattern, corresponding point by point to all or part of the image, for reconstituting the image at a receiving point, the devices being adapted to stimulate the nerves of touch electro-sensorially. In the reading aid shown in Fig. 1 the reading matter 1 is set on a carriage 2 movable in the direction of the lines by a screw 4 and at right angles thereto by a screw 5, and is illuminated by the device 10. A device 11, 12 in the forepart 7 of a casing forms an image of the reading matter on a target mosaic 14 on the rear part 9, the latter being movable by means of knob 6 to form the image, bellows 8 permitting lengthwise movement. A mirror may be inserted to reflect an image on to a focusing screen 18 to aid focusing. The target 14 comprises a series of elements 15, e.g. selenium light-sensitive resistance cells, connected by a common conductor 22 to an amplifier 28 and by individual lines 21 to separate studs 24 of a commutator device 25. The rotary arm 26 of the commutator completes a circuit for one cell at a time through 27 to amplifier 28, which is supplied at 29. The amplifier is connected on the output side by a common conductor 37 and synchronously driven commutator 30, 31, 32, 33 to the receiver comprising a series of bipolar electrodes, the outer elements of which are connected to wire 37, and the inner elements to separate wires 33. The positions of three electrodes 35, 36 which have been more or less electrified by the illumination of cells 15 can be detected by feel, e.g. by feeling one electrode at a time with a finger tip, or by applying the whole surface of the receiver to a larger area, such as the chest. Preferably the characters are projected white on the mosaic, as in Fig. 4, but they may be projected black with the remainder white. It is therefore advisable to sensitize the non-illuminated cells and desensitize the illuminated cells. This may be accomplished, for example, by introducing a Wheatstone bridge into each unit compound of a cell and its receiver, as in Fig. 5. The bridge can be fed by alternating current, when one or more resistances can be replaced by inductance coils or condensers. A similar reversal is obtainable by the use of relays or inverting effect amplifiers. Distortion brought about by the use of conventional commercial lenses may be corrected by a distorted arrangement of the cells of the mosaic, or the units of the receiver. The stimulus may be increased in certain areas by grouping some electrode pairs together, the elements of each group being connected to a common cell of the mosaic. Neutral filters may be used to correct variations caused by the non-uniformity of the lens. A coloured scene may be explored by inserting a series of colour filters across the path between the scene and the mosaic so that the light falls within the confines of a single filter element, and judging by feel the result with each separate filter when a large coloured area is to be explored a multiple unit coloured filter, as in Fig. 10, is placed near the .mosaic. In the construction shown in Fig. 11 the number of cells and units is reduced, the cells being located on the fingers and the receivers on the opposite side of the fingers or any other part of the body. The elements may be secured to a glove (the operator passes his hand across the beam 13 to explore the outline of the black or white characters). In a further apparatus for exploring in all directions, the electrical arrangements are the same as in Fig. 1, but the image is produced on the mosaic, as in a camera, by a focusing lens fixed at the front of a shorter casing. In a further similar apparatus the amplifier is dispensed with and the apparatus is energized by an electric cell or battery. A pantograph may be used in conj unction with the apparatus shown in Fig. 1, a reading pointer actuated by the operator replacing the " reading matter " 1 of Fig. 1. This enables the operator to read his own handwriting as he writes.