(57) A table lamp incorporates a switch (64) operating device consisting of two members
(4, 30), one member (1) being located in the base (1) of the lamp and the other in
the stem (11). The stem (11) is mounted in the base (1) for rotational movement between
first and second positions representing "on" "off" positions of the lamp switch. The
member (4) located in the base (1) includes a horizontal annular portion (60) from
which projects two upwardly directed triangular shaped cam surfaces (61, 62) positioned
at either end of a diameter of the annulus. One end of a spring loaded plunger (65)
projects through the annular portion (60) between the cam surfaces (61, 62) and the
other end acts, when depressed, to close the contacts in a micro-switch (64) located
in the base (1). The other member (30) located in the stem (11), includes a surface
adjacent and parallel to the annular portion from which depend two spring loaded plungers
(35, 36) spaced apart to co-operate with the cam surfaces (61, 62) such that rotation
of the stem (11) with respect to the base (1) causes movement of the plungers (35,
36) over the cams (61, 62) from one side to the other i.e. between the first and second
positions. A stop means (54, 70) is provided to restrict the degree of rotational
movement. A third plunger (50) depends from the surface of the second member (30)
and is positioned such that when the members are in the first position it acts to
depress the plunger (65) in the first member (4) so that the switch (64) is "on",
and when the members are in the second position it is out of contact with said plunger
so that the switch (64) is "off".
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