Patent GB-720863-A (GB)
Title: Improvements in or relating to printing telegraph apparatus
Inventor: SALMON REGINALD DENNIS
IPC: H04L12/08
Filed: 1953-03-31
Abstract: 720,863. Type-printing telegraphy. CREED & CO., Ltd. March 31, 1953, No. 8875/53. Class 40 (3). An arrangement for detecting a combination of elements, all of one kind, in a perforated tape passing through a transmitter comprises a relay operated by the occurrence of an element of another kind, a locking circuit for the relay, means for opening the locking circuit during the start ele. ment of a signal combination and means operative during the stop element following the signal combination for recognizing the condition of said relay. The arrangement is used to control the switching over from an automatic numbering transmitter to a message transmitter by the letter-shift (all-mark) combination, in a modification, by an allspace combination, which can be regarded as the feeding of blank tape. When a message is to be sent from the transmitter, Fig. 2, the operation of a key TOA energizes relay AA - which locks up over 3 contacts aa1, d1 and c1. Additionally, a relay BA - is operated and remains operated by 4 contacts 4, 5 held closed when key TOA is released by a pecker P2 engaging the tape. The closure of contacts aa3, ba2, Fig. 1, energize clutch magnet CM1 of the automatic transmitter. During the signal combinations other than letter-shift, relay HS/1 is operated and locks up over hs1 and contact SS1 which is closed except during the period of the start element. When the latter-shift combination occurs, relay HS/1 is not operated and the closure of contacts ss2 during the stop element energizes relay C/3 which at contact c3 opens the circuit of magnet CM1 and at contact c1 opens the circuit AA C of - which releases. When - releases, the 3 3 closure of contact c1 operates the magnet CM2 of the message transmitter which sends signals from contact TC2 to the line L until the end of the tape allows contacts 4, 5 to open, breaking the circuit of relay BA/4 which at contacts ba3 opens the circuit of the clutch magnet CM2. If tape is inserted in the transmitter, Fig. 3, whilst that of Fig. 2 is in operation, relay AB/3 is operated and held, but BB/4 cannot operate until BA/4, Fig. 2, is released. When BB/4 operates, the message number transmitter operates via contacts ab3, bb2, and when relay C/3 is operated, the all-mark combination relay AB/3 is released and the message in the transmitter, Fig. 3, is sent when relay C/3 releases and contact c2 closes. If the tape bearing the message numbers breaks or becomes exhausted, contacts TON, Fig. 1, open, relay D/3 releases, and by the closure of contact d3 a bell B is sounded. Also at contacts d1, d2, the circuits of magnets CM2, CM3 are opened. In a modification, Fig. 4, the switching over to a message transmitter is effected by blank tape, i.e. an allspacing combination. If a mark element occurs relay HS/1 is operated over constant SS1 closed except during the period at the beginning of the start element and locks up over contact hs1 and contacts SS3 which are open solely during the middle of the start element. If, however, the combination is all-spacing, relay HS/1 does not operate and, as in the previous arrangement, relay C/3 is separated when contacts SS2 are closed during the period of the stop element and effects the switching-in of a transmitter prepared by the insertion of a tape bearing the message to be transmitted. Specification 291,854, [Class 40 (iii)], is referred to.