Patent GB-431855-A (GB)
Title: Improvements in and relating to calling impulse transmitters for automatic telephone systems or the like
IPC: H04M1/56
Filed: 1933-12-12
Abstract: 431,855. Impulse transmitters. SHIPTON, E., 12, Dartmouth Street, Westminster, and KENNEDY, 0. D., Talland Cottage, Dawes East Road, Burnham, Buckinghamshire. Dec. 12, 1933, Nos. 34988/33, 7176/34, and 23565/34. [Class 40 (iv)] An impulse transmitter on which a complete seven-digit number may be set up and exhibited before the transmission of impulses is initiated comprises a series of rotary thumbdiscs one for each digit, the thumb-discs being associated with digit-determining discs which control the selection of the appropriate sets of impulses from a continuously-generated train. In one construction, Figs. 1, 2, the thumb-discs 2 ... 8 are freely mounted on a shaft 9, the four numerical discs 5 .. 8 being rigidly connected to impulse-determining discs 18 .. 21, whilst the three letter discs 2 .. 4 are connected to the corresponding impulse-determining discs 15.. 17 through a lost-motion device such as a pin-and-slot coupling 44, 45 so that the different letters of a group (e.g. A, B, C), may be separately exhibited although giving rise to the same number of impulses. Each impulse-determining disc has a centring arrangement comprising a spring 23 engaging a scalloped disc 22. When the complete number has been set up, handle 34 is depressed winding up the clockwork mechanism 33 and freeing it to permit spindle 24 to make one revolution. A continuous stream of impulses is produced by cam 35 the contacts of which are however normally short-circuited through a shunt circuit comprising contact discs 40 (engaged by brushes 42), staggered pairs of contacts 26 .. 32, and conducting collars 39 in series, the short-circuit being opened at intervals to transmit the required digits by the successive engagement of wipers 26 .. 32 with selected teeth a .. j of the impulse-determining discs 15.. 21. An eighth thumb-disc 1 may be provided for use on special calls, e.g. for dialling O, or for use with a house system. In a second arrangement, the shaft bearing the staggered contact-pairs passes through the discs 2, 15, &c., the impulse discs being provided with internal teeth. The thumb discs and impulse discs are secured together at their peripheries, rigidly by bolts in the case of the numerical discs and through a lost-motion device comprising a radial projection moving in an internal groove in the case of the letter discs. In another construction, the thumb discs adjust sectors which mask variable numbers of teeth on the impulse discs, or variable portions of a continuous groove. The pairs of contacts relating to the different digits are connected up in succession over a commutator. In this case, the main shaft makes seven revolutions, but this may be halved by arranging the teeth of alternate discs on opposite portions of their peripheries and again halved by arranging one set of teeth to occupy only one quadrant of a disc. In the construction shown in Figs. 9, 10, only one impulse disc 90 is used, the thumb wheels 2 .. 8 being connected coaxially with masks 97 .. 91 located on different portions of the disc and limited in movement by stops 101. The time of actual impulsing may be halved by using two discs with toothed portions on one corresponding to plain portions on the other. Means may be provided for making adjustments between the various parts of the mechanism. The first Provisional Specification describes a modification in which a wiper controlling the short-circuit across the impulse-generating springs travels over a bar, the travel being variably interrupted by the setting-up means, for example, by the insertion of insulating material or by displacement of the wiper by means of a cam. Specification 381,532 is referred to.