Patent GB-1171778-A (GB)
Title: Improvements in Latching Devices.
Inventor: ELBROW DEREK JOHN CHARLES
IPC: H01H13/56
Filed: 1966-03-04
Abstract: 1,171,778. Releasable fastenings. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. 15 Feb., 1967 [4 March, 1966], No. 9584/66. Heading E2A. [Also in Division H1] A pushbutton-operated latching device for push-on/push-off finger-operation of a suitable switch, as shown diagrammatically in Fig. 1A see also H1 comprises a switch-actuating plunger in the form of a plate or block 2 which is mounted in relation to a cooperating stationary part 4 for reciprocating switch-actuating movement of the plunger and constitutes a latch having within it a shaped opening 6 accommodating a rotary stop 8 for terminating successive strokes of such reciprocating movement, the stop being pivotally mounted at its centre of gravity, at a point fixed in relation to the cooperating part, for rotary movement of the stop in a plane parallel to the direction of the reciprocating movement, and the profiles of the stop and of the shaped opening 6 in said plane being such that the stop can at times assume an angular orientation in which it can enter a recess 12 at one end of the opening to terminate such a stroke in one sense with the plunger in a certain position, that at other times the stop can assume another angular orientation in which it cannot enter the recess but comes to rest across the mouth thereof to terminate another such stroke in the same sense with the plunger in a different position, and that during successive strokes in the opposite sense the plunger bears against the stop in such manner as to rotate it into the next one of such alternate angular orientations in which next one it will remain until it engages the plunger at the first mentioned end of the shaped opening preparatory to terminating the next stroke in the first mentioned sense, the plunger being biassed for return movement in this sense and arranged for finger-operation in the opposite sense. In the construction shown in Figs. 3 and 4b the switch operating plunger 30 equivalent to the plate 2 is guided for sliding movement in a mounting unit 50 by means of a longitudinal rectangular slot 34 in each of its narrower sides which engage rectangular projections 70 in the mounting unit; the plunger has a stem 36 which passes through an opening 72 in a bottom plate 58 of the mounting unit, a spring 74 surrounding the stem 36 and biassing the plunger upwardly as shown. A push button 88 is secured to the top of the plunger. The stop 69 which conforms to the stop 8 is carried by the mounting unit and the arrangement is such that depression of the plunger causes a bevel 48 of the plunger to actuate a microswitch, the microswitch being released by a further depression of the plunger which upon release moves back to its original position. As shown two plungers and two microswitches are carried by the mounting unit 50 the plungers and switches operating independently. The assembly of the mounting unit with the two plungers and the microswitches is used for a telephone instrument the mounting unit having a U-shaped extension 62 which engages a central tongue 96 of a frame of the telephone instrument a tapering lug 66 on the bottom plate of unit 50 being inserted into a horizontal flange 98 formed integrally with the plate 90 at its lower edge and a barb 64 on the unit 50 entering a hole 100 in the plate 90 to retain the unit in position. Instead of the shape shown the step can be triangular and the spring is suitably modified.