Patent GB-389999-A (GB)
Title: Improvements in or relating to keyboard controlled current impulse transmitters
IPC: H04L17/06
Filed: 1932-04-20
Abstract: 389,999. Type-printing telegraphy. FULD & CO. TELEPHONUND TELE. GRAPHENWERKE AKT.-GES., H., 136, Mainzerlandstrasse, Frankfort-on-Main, Germany. April 20, 1932, No. 11367. Conven. tion date, May 1, 1931. [Class 40 (iii).] In a keyboard transmitter in which the depression of a key operates intermediate con. trolling members selectively setting a number of movable cams effecting during their rotation by an auxiliary force the transmission of the signal current-impulses, the intermediate members are constructed and mounted so that there is no operative connection between the cams and the keys throughout one revolution of the transmitting cam shaft. The impulse transmission is effected by a contact member 10 actuated by a member 26 co-operating with start and stop cams St, S respectively and with cams 7 selectively moved in a longitudinal direction to engage the member 26. Upon the depression of a key, for example, the key 25, the operations take place in two stages. Primarily one or more of the bars I .. V are depressed and draw down corresponding members 19, removing projecting noses 22 on the bell cranks 20 out of their operative position with respect to projections 21 on locking discs 13. The members 13 which are mounted on a shaft 1 rotated from gearing 3, 4 through a clutch 2, are formed with pear-shaped slots 14 and are normally biased by springs 12 so that the narrow end of the slot engages a notch in one of the five pins 6 which correspond to the permutation bars I .. V. On the completion of the depression of a key, a sixth bar VI rocks a clutch-controlling member 24 removing a stop from the clutch 2 and allowing the shaft 1 to be rotated for one revolution. The shaft 1 carries disc members 11 in which the pins 6 are slidably mounted, and on rotation of the discs 11 and the locking members 13, the projections 21 selectively engage the noses 22 of the bell cranks 20 which have not been rocked out of operative relation, with consequent slight rotation of the corresponding locking discs 13 relative to the shaft 1 against the springs 12 and the disengagement of the narrower end of the pear-shaped slot from the associated notch. The corresponding pins 6 simultaneously snap forward under the action of compression springs 16, and the associated cam members 7 are moved to a position in which they actuate upwardly the contact controlling member 26. The cams 7 are formed with lugs 8 projecting in the direction of the axis of the shaft 1 and arranged to engage a fixed restoring member 9 after the impulse has been transmitted so that the pins 6 are restored to the left against the action of the springs 16 when they are retained by the notches of the pins engaging the narrow end of the pear-shaped slots in the locking discs 13. The operative surfaces of the cams may vary in length and may increase progressively so that the stop impulse is of longest duration. To prevent rebound of the clutch member 2 at the end of a revolution an additional stop member, comprising an arm 27 with a roller 28 engaging a recess 29 in a member secured to the clutch, is provided.