Patent GB-441541-A (GB)
Title: Improvements in or relating to telephone instruments and signalling systems
IPC: H04M17/02
Filed: 1934-05-17
Abstract: 441,541. Automatic exchange systems. COHEN, B. S., 9, Lebanon Park, Twickenham, Surrey, and GREGORY, H. J., 19, Dean Court, Wembley, Middlesex. May 17, 1934, No. 14885. [Class 40 (iv)] [See also Group XVIII] In sub-station prepayment equipment with mechanism for registering deposited coins, charges for successful calls and for rental are deducted from the credit indicated by the equipment. The deduction for calls may be made when the subscriber performs a manual operation to make an established connection effective and the deductions for rental may be made by a magnet operated over a neon tube by pulses of high-voltage from the exchange. Outgoing calls are prevented if rent is in arrear, but subject to a predetermined limit of arrears, incoming calls may still be received. Insertion of a coin into slot 2b couples a sleeve 2 to a spindle 2a which is thereupon rotated by an external knob through 180‹ after which the coin drops into receptacle 2d. The sleeve 2 is geared to a spring drum 4 and by differential gear 14 to the spindle 15 of an indicator 16 which may register up to say 10 shillings, after which a stud 43 carried by a disc on the indicator spindle trips a lever 45 into the path of a projection 46 on sleeve 2 to prevent it being rotated back into the coin insertion position. Parts of a shilling are indicated at 33. To make a call, the instrument is removed from the cradle R2 permitting lever 18, Fig. 5, to rise and operate the usual spring set 20, and a knob 23 is turned to rotate a spindle 26 clockwise against the action of a spring. The spindle carries an arm 25 operating contacts 27 which shunt the transmitter and remove a shunt from the impulse springs, the spindle being locked in operated position by a collar 26a thereon having a recess engaged by a projection on lever 18. The number is dialled and if the call is unsuccessful, replacement of the receiver restores the apparatus to normal without affecting the indicator. If the call is successful, the subscriber presses a spring-loaded button 28 to rock a fork 29 which releases a pin 30 on a spindle 31 geared to the spring drum and stops the spindle by engagement with another pin on the spindle. The button 28 is then released and in a similar fashion permits further limited rotation of the spindle. The spring drum drives spindle 15 of indicator 16 in a reverse direction by means of the differential gear. When the button was pressed, a spring set 50 operated to remove the shunt on the transmitter, the set being held operated by a spring-controlled lever 51 which rises behind the spring set. On replacement of the instrument, lever 18 is depressed releasing spindle 26 which rotates slowly in a counter clockwise direction under control of an escapement 54 to which it is geared. A projection on the spindle 26 depresses lever 51 to permit restoration of spring set 50, while a spring- controlled projection 56 which was ineffective during the clockwise motion now depresses a lever 59 controlling springs 60 momentarily to open the line to prevent any fraudulent operations. Deductions for rental are made by impulses of 150 volts from the exchange which operate magnet 61 in series with a neon lamp 63. The magnet operates on a projection 64 carried by fork 29 to effect backward rotation of the indicator as previously described. When the indicator reaches zero the cam disc 44 releases a lever 66 which locks arm 25 so that spindle 26 cannot be rotated, the press button 28 being also looked by arm 25. Further rental deductions (arrears), up to say 4 units, may then be made after which stud 43 opens the line at springs 67.