Patent GB-645363-A (GB)
Title: Improvements in or relating to braille or like reading apparatus
IPC: G09B21/00
Filed: 1947-09-05
Abstract: 645,363. Braille-reading apparatus. INTERNATIONAL BUSINESS MACHINES CORPORATION. Sept. 5, 1947, No. 24496. Convention date, Sept. 19, 1946. [Class 146 (ii)] Apparatus for sensing perforations in a record tape 20 and translating the intelligence thereon by the setting of positionable pins 25 on a belt 26 to represent Braille, comprises a tape-feeding mechanism advancing the tape past a series of sensing elements 61 interconnected with electrical contacts controlling the energization of electromagnets 86 having armatures 94 operative to engage and position the pins into coded groups ; the belt 26 is advanced in synchronism with the tape by a feeding mechanism which includes means for restoring projected pins into their normal position after they have passed a reference position 28. Each character is represented on the record tape by one or more holes of a transverse row of six holes 80, Fig. 10, which are translated by the apparatus into Braille codes on the belt 26 represented by raised pins 25 arranged in two successive transverse rows of three holes with the pins slidable therein, and the three holes of a row on one side of the centre line of the record tape control three pins in one transverse row on the belt 26 and the other three holes on the other side of the record tape control the pins 25 in the succeeding row on the belt. One character is sensed and set up during each cycle of the machine corresponding to one revolution of shafts 37, 41, Fig. 2, geared to rotate at the same speed. The shaft 37 is driven from a motor 29 through an electrically controlled one revolution clutch 36 and feeds the tape 20 one step per cycle past the sensing elements 61 by a ratchet-and-pawl mechanism 45, 46, 51, 54. The belt 26 is endless and is fed over a table 144, Fig. 6, at a constant speed by sprocket wheels 124, 125 driven by worm gearing from a shaft 44, Fig. 2, geared to the shaft 41. The belt 26 also passes over a sprocket wheel 126 driven from the shaft 44 by a worm 114 which is rotatable with and slidable axially along the shaft. The worm 114 is reciprocated axially twice during each cycle by a cam 115 so as to cause a section of the belt, controlled by wheel 126, to be stationary for two periods during which the pins in a pair of successive rows are projected. The projection is effected by three electromagnets 86, Fig. 6, whose armatures 94 have bent ends 94a to engage the pins. If code holes are present in the record tape one or more of the pins 61 pass through the tape and cause electrical contact springs 66, Fig. 8, to close contacts 67, thus completing electrical circuits to operate one or more of the electromagnets 86. Mounted on the shaft 37 are three cams 87 engaging change-over switches 89 to 91 so that during the first stationary period of the belt 26, the three electromagnets 86 are connected in series with the contacts 67 corresponding to three holes on one side of the tape 20 and during the second stationary period are connected to the other three contacts 67. The magnets 86 cannot operate if a record tape is absent since a large diameter pin 76 mounted on a contact spring 77 and normally held downward by the tape, is free to rise and thereby break a common circuit in the current supply to the sensing contact 66, 67. The elements 61, in a later part of each cycle, are restored by a rocker mechanism 69 to 74, Fig. 8, which is rotated against the action of the spring 72 by a further cam 75 on the shaft 37. After the pins have been set and read by touch they are pushed back into normal position in the belt 26 by a spring loaded roller 145, Fig. 6. The belt 26 is made from resilient plastic material, e.g. polyvinyl butyral containing predetermined pattern groups of punched holes into which are inserted metallic pins 25. By regulation in the temperature at which the belt is punched the resulting holes have convexly shaped walls with the diameter, in the centre of the material, less than the diameter of the pin and so serves to grip the pin in position. The one revolution clutch 36 is operated by a solenoid 32 controlled by a number of electrical circuits which ensure that the machine returns to the commencement of a cycle irrespective of when the main switch is opened, e.g. if the switch is opened at a point in the cycle between zero and 280 degrees the machine continues to drive to 354 degrees after which it coasts to 360 degrees, and if the switch is opened after 280 degrees the solenoid 32 holds the clutch engaged and the machine passes through 360 degrees and stops at the end of the subsequent cycle.