Patent GB-736439-A (GB)
Title: Safety spring lock
IPC: E05B45/12
Filed: 1953-02-23
Abstract: 736,439. Locks. MARTENS, D. G. Feb. 23, 1953, No. 5026/53. Class 44. [Also in Group XXXVIII] In a safety-spring lock having an alarm-preparing position in which an electric alarm circuit is brought to alarm condition by inward movement of the latch, a blocking device of known kind which is operable manually for mechanical blocking of the lock, is adapted by its movement to the blocking position to bring the alarm circuit into an alarm-preparing condition and in the blocking position permits inward pushing of the latch a limited distance sufficient to bring the circuit into alarm condition but insufficient to permit opening of the door. In the arrangement shown, in which a sliding latch 4 is actuated by an arm 9 rotatable by a knob 10 on one side of the lock, or by an arm 9<SP>1</SP> rotatable by a cylinder lock on the other side, a blocking member 11 guided for traverse movement in a plate 12 on the lock case 1 by reverse rotation of the knob 10 or the key of the cylinder lock, is formed with a lug 14 for engagement, in the locked position of the latch 4, with a flange 8 of a latch slide 5 and is engageable by both the arms 9 and 91. A stopping stud 15 projecting inwardly from the member 11 is also engageable by both arms 9 and 91, and in the locked and unlocked positions of the latch, Figs. 4 and 6 respectively, is moved by the member 11 to block the latch, into openings 18 and 19 at the inner end of the slide 5. The blocking member 11 is arrested in operative and inoperative positions by a spring-loaded plunger which co-operates with notches on the side edge of the member 11. A plate spring 20 carried by the slide 5 carries an inwardly projecting pin which is pushed back by the stud 15 when the member 11 is moved to a blocking position in the closed position of the lock, but which on slight inward pushing of the latch to an intermediate position, snaps on to the rear side of stud 15 to block further movement of the slide in both directions. Terminals 21, 22 insulated from the lock casing are connected to an alarm circuit, the terminal 21 carrying a plate spring 25 which in the operative position of member 11 engages the lug 14 thereon, and the terminal 22 being in the path of a plate spring 30 electrically connected with the slide 5 and being out of contact with the spring in the fully opened and fully closed positions of the lock. In operation, movement of member 11 to a blocking position when the lock is closed, closes contacts 25, 14, but contacts 30, 22 remain open until and unless a slight inward push on the latch releases the pin on the spring 20 to block further movement of the latch and to complete the alarm circuit through contacts 30 and 22. Annulment of the blocking and of alarm preparation from the inside only, may be effected by arranging that lug 14 does not project into the path of the arm 9<SP>1</SP>. Annulment of the blocking by the use of the key only, may be effected by means of a modified arm 9, Figs. 7 and 8 (not shown) which, while able to withdraw the latch in the unblocked position, is unable to move the member 11 out of blocking position. The lock may be blocked from the inside in open and in closed position, by means of a knob on the member 11. The arms 9 and 9<SP>1</SP> may be interchanged to render the safety device inoperative from inside only. In another modification, the contact on the member 11 may be replaced by a displaceable bar entrained by movement of the member 11 to the blocking position and returned by movement of one of the arms 9 or 9<SP>1</SP>. In a further modification, one pole of the circuit may be connected to the lock case and the other to both terminals 21, 22, the contacts 25, 14 in this case being interrupted in the blocking position of member 11 and the contacts 22, 30 being closed except in the intermediate position of the latch.