Patent GB-270745-A (GB)
Title: Improvements relating to impulse emitters for subscribers' stations of automatic telephone exchanges
IPC: H04M1/515
Filed: 1927-05-06
Abstract: 270,745. Barth, C., and Domaschko, A. May 6, 1926, [Convention date]. Impulse transmitters for automatic exchange systems of the type in which the whole of the wanted number is first set up and the selective impulses are then sent out in successive trains over the a-wire separated by single impulses over the b-wire. Separate gear trains which start and stop one another alternately are provided for the a- and b-impulse mechanisms, each train being only connected up for the time necessary to send the required number of impulses, so that the whole time taken up in transmitting the wanted number is a minimum. The impulses are generated by spring-controlled pivoted arms which slide over pins on a rotating wheel, the duration of the impulses being readily adjustable. Provision is made for supporting one or more digits so that the same instrument may be used for numbers having different numbers of digits. Means may also be provided for preventing the transmission of impulses until an idle group selector has been seized and for causing the connection to be released at the conclusion of impulsing if the receiver has not at that time been removed. Fig. 9 shows the substation circuit arrangements. Setting mechanism. Between discs 1, 4, Fig. 1, are mounted guided racks 6 which are adjustable radially one for each digit by means of toothed wheels 9 rotatable by external buttons. Number discs 11 moving with the wheels 9 indicate through windows in the casing the settings of the various racks. Impulse transmission. The starting crank 74, Fig. 5, is connected through a claw coupling 75, 76 with a disc 66 on a shaft 69, a slot 67 on the disc being held in engagement with a pin 68 on the shaft by means of a spring 72. When the crank 74 is given one rotation, the tension of the driving spring forces disc 66 to rotate relatively to pin 68 so that the disc moves to the left and carries with it a lever 65 on a shaft 64. Normally a second lever 60 on the shaft 64 engages a recess in a wheel 58 of the b-impulse gear train. and a projection 61 engages a pin 62 on a wheel 44. The movement of lever 65 frees wheels 58, 44 so that the b-impulse mechanism, Fig. 4, is started. Upon the first movement of disc 1 which is geared to this mechanism, projections 80 riding out of grooves 79 cause sleeve 78 to disengage the parts of the coupling 75, 76, so that further movement of crank 74 during impulse sending is ineffective. The b-impulsing arrangements comprise an arm 51 engaging with pins 57 on a wheel 42 which, in common with discs 1, 4, makes one revolution per connection. The aimpulse mechanism, Fig. 3, comprises gearing 12 - - 20 which is normally held at rest in the position shown by means of an arm 21 on the wheel 15 engaging a projection 22 on a pivoted lever 23, the latter being held by a pawl 28 engaging a quadrant 27. When the first b-impulse has been sent, a projection 5 on the disc 4 raises a second pivoted lever which withdraws the pawl 28 but further locks the gearing by a tailpiece 30 engaging a pin 31 on the wheel 18. The lever 23 now moves under control of spring 25 until an extension 34 engages the end 39 of the first digit rack 6. When projection 5 passes the end of lever 32 the tailpiece 30 frees the gearing, whilst at the same time pin 52 on lever 53, Fig. 4. locks the b-mechanism. During the running of the a-mechanism, impulses are sent out by the engagement of arm 35 with pins 36 on wheel 14, whilst at the same time quadrant 27 and lever 23 are moved step by step back to normal by teeth 37 on the shaft of wheel 15. When lever 23 reaches its normal position the mechanism is stopped by the engagement of arm 21 and projection 22, whilst the engagement of lever 23 with an extension of lever 53, Fig. 4, causes the b-mechanism to send a further impulse and to advance discs 1, 4 into position for the transmission of the next a-digit. The transmission of the remaining digits then takes place in a similar manner. By altering the distance apart of the pins 36, 57 and the length of the arms 35, 51 the period of impulse closure may be adjusted as desired. Suppressing one or more digits. The shaft of wheel 58 carries a two-part disc. each part 85<a>, 85<b> of which is of cam formation, the two parts being relatively adjustable. The earth connection to the b-wire is made over one arm 81a of a pivoted member 81, Figs. 8 and 9, the hook 84 of which can engage only with the higher portions of the disc members 85a, 85b. Thus, by so adjusting these members that the earth connection to the b-impulse contacts is not supplied until after the b-gearing, including the disc 85<a>, 85<b>, has moved through the angle corresponding to the first digit, the initial starting b-impulse will not be sent until this connection is made and the first a-digit will consequently be ineffective. The other end 81<b> of the lever 81 controls contacts 86, 87 in series with the telephone instruments T in such a wav that those contacts are only bridged when all the impulses have been sent. The act of raising the receiver does not therefore interfere with impulsing. Preventing transmission of impulses until an idle group selector has been seized. In order to effect this, a second arm 100, Fig. 7, on the shaft 64 moves into engagement with a pin 102 on the other side of the wheel 44, so as to lock the mechanism again as soon as the first b-impulse has been sent. The return movement of the shaft 64 is prevented by the spring-controlled pivoted armature 106 of an electromagnet 108, which engages with a disc 105 on the end of the shaft 64. The disc 105 in its displaced position connects the magnet 108 over contact 109 to the a-wire, and when an idle group selector is found the connection of battery to the a-wire energizes magnet 108 which removes armature 106 from engagement with disc 105, thus permitting shaft 64 to return and remove the locking projection 101 from the path of the pin 102. Releasing connection if receiver has not been removed when impulse transmission is completed. A pin 115, Fig. 8, on arm 81<b> rides down an insulated face 111 of a pivoted spring- controlled triangular block 110 during the movement of hook 84 over the higher parts of disc 85<a>, 85<b>, but at the end of impulsing the movement of the hook into the recessed portions of the disc causes pin 115 to ride up the conducting lower face of the block 110, and if the receiver has not been removed at this time the conducting connection causes the a- and b-wires to be connected together to release the connection.