GB1016142A - Improvements relating to retractive electric switches with pilot lamp holder - Google Patents

Abstract

1,016,142. Switches held set and freed mechanically; indicators for switches; lampholders. ELECTRIC & MUSICAL INDUSTRIES Ltd. July 27, 1962 [July 27, 1961], No. 27191/61. Headings H2B and H2E. A retractive switch comprises a spring- loaded movable member 5 carrying a conducting lampholder 3 to which electrical connection is made via the helical loading spring 7. Connection to the insulated centre contact 18 of the lampholder is made via a further spring 39. The terminal connections 28, 29 for the two mutually insulated springs are led out through an insulating bushing 21 insulatedly mounted on the metal base plate 20 of the switch frame. Depression of a button 1 (Figs. 3, 7, not shown) causes latching of member 5 in its depressed position by a pin 8 on a resilient arm 9 engaging in a cam groove 10 formed on a side of member 5, the pin 8 travelling round branch 13 of the groove to a latching position at point 12. A second depression of button 1 releases the latch, and the pin 8 travels anticlockwise round the remainder of the groove 10 to its starting position, where button 1 is in its outermost position. Extensions 14, 15 of groove 10 allow for over-travel. Strip contacts 4 carried by member 5 engage fixed-contacts such as 42, 43 or 43, 44, on insulating plates such as 45 in the two positions of member 5 (Fig. 7, not shown). The lamp in lampholder 3 may be energized on depression of button 1 or may be energized independently as required. The cam groove 10 is of cardioid shape as shown or of saw-tooth shape (Fig. 8, not shown). Button 1 is of translucent or transparent material, and encloses a lamp (not shown) in the lampholder 3.