Patent GB-412541-A (GB)
Title: Improvements in impulse transmitters particularly for use in automatic telephone systems
IPC: H04M1/274
Filed: 1932-09-22
Abstract: 412,541. Impulse transmitters. HERING, W., 6c, Waltroper Weg, Lichterfelde, Berlin. Sept. 22, 1932, No. 26368. Void [Abridged as open to inspection under Sect. 91 of the Acts, Sept. 29, 1932]. [Class 40 (iv).] In an impulse transmitter in which a continuous stream of impulses is variably split up by the control of short-circuiting contacts so as to transmit as the result of a single setting- operation any one of a plurality of predetermined multi-digit numbers, the short-circuiting contacts are fixedly mounted in the apparatus. In the apparatus shown in Figs. 1-3, the impulsing contacts 5, the rotary cam 4 and speed-regulator 7 are mounted as a unit on a bracket 8, the cam 4 being driven through a pinion 9 from a spring 2 which is wound by depressing a pivoted bar 11 carrying a toothed sector 1<b>. The short-circuiting contacts 10 are controlled by an arm 16 at the end of a rod 15 secured to a spring pawl 14 which is slidable by an external handle 21 along a fixed bar 20. A drum 3 having a disconnectible coupling 29 with the spring drive 2 is provided with holes 6 for the insertion of sets of cams 12, 13, corresponding to particular subscribers' numbers. When pawl 14 engages the lower cams 13, contacts 10 close to short-circuit springs 4, and when the higher cams 13 are engaged, contacts 10 are opened to permit the transmission of a certain number of impulses, whilst contacts 11 shunting the telephone instruments F are closed. When the last cam 12<a> is passed both springs 10, 11 are opened. Alternatively cams of only one height may be used, contacts 11 closing when pawl 14 engages the drum surface and contacts 10 when a cam is engaged. When leaving the last cam the pawl is further raised to open both contacts 10, 11, and is locked in this position under the control of bar 11. With such arrangements the drum 3 comprises a series of separate discs 31 and the cams may be in the form of radial arms 3k, Fig. 7, with spring catches 3<b> ; spring arms 3<k>, Fig. 8, with locking projections 3<c> ; riders 3<e>, Figs. 9, 13, with locking projections 3<c> ; or spring-controlled riders, Fig. 14, with teeth 3h registering with internal teeth, 3<g>, on the disc rim. In another arrangement, Fig. 17, the pawl 14 is directly controlled by teeth 3<r> inserted in the circumference of the disc 3<1> as required. In other modifications, a separate pawl movable into and out of operative position as required is provided for each disc 3<1>, and such pawls may be coupled to the shaft 15 by electromagnets controlled by push-buttons. The contacts 10, 11, may be directly operated by an electromagnet controlled by separate pairs of contacts engaged by the cam discs. The apparatus is formed as a unit independent of the usual instruments and may have a writing tablet or calendar sliding into the lower part of the casing. A lamp or audible signal on the top of the casing may indicate whether the receiver is off the hook. Contacts 17, 18, Fig. 4, are provided to disconnect the unit in case of emergency, and these may be operated by an arm 26, Fig. 3, acting on a lever 25, Fig. 2, when the handle 21 is moved to a particular position, or automatically on the removal of the plug from a plug-and-socket connection. The connections to the apparatus are preferably enclosed in metal sheaths.