Itt Corporation

Jon P Zoller

Jeffrey J Norris

A switch assembly is provided with a short travel switch (16, FIG. 3) activated by a push button that has a long travel both before and after closing of the short travel switch, and which provides a substantially constant spring rate throughout push button travel, with minimal noticeable disruptions. The switch assembly includes an inner plunger (32) which depresses the short travel switch, and an outer plunger (44) or keystem coupled to the push button. An inner spring device (46) couples the inner plunger to the housing, and an outer spring device (52) couples the two plungers, so the springs act in series. The preloads of the two spring devices are substantially the same, and the inner spring has a lower spring rate than the outer spring. As the keystem is depressed, both springs begin to compress until the inner plunger contacts the short travel switch. Continued depression of the push button and keystem results in compression of only the outer spring, there being a smooth transition because the preload of the outer spring has already been exceeded. The mechanism lies in a passage of a housing, the housing including a bar (102, FIG. 5) that extends across the passage, with the keystem having grooves that receive the bar end portions. Pin sockets (116) are mounted on the middle of the bar to receive lamp terminals, and a pair of conductors (142) have flattened ends (144) receiving the pin sockets.

Dual plunger switch

A multi-pole switch is provided which has a large air gap between contacts in the open state, and which requires medium to high actuating forces while providing tactile feedback to indicate that full actuation has occurred. The switch includes a pair of sheet metal shorting contacts (22, 24, FIG. 2) each extending in a largely rectangular loop, with one long side (26) and the opposite short sides (30, 32) forming a clamped outer region (34), and with the other long side forming a beam (28) that can be deflected down towards a pair of fixed switch contacts (50, 52). The outer region (34) is deflected so the beam (28) is upwardly bowed. The beam includes a main beam portion (36) and fingers (46, 48) extending from it, the fingers being deflected against the switch contacts when the main beam portion is deflected. Bowing can be facilitated by a third switch contact (70) lying under the other long side (26) of the shorting contact. An actuator (12, FIG. 3) includes a plunger (56) with a pair of bosses (60, 62) lying near opposite sides of the main beam portion of each shorting contact. A snapdome (100) lies over the plunger to provide tactile feedback, and an elastomeric button (110) lies over the snapdome.

Growing community of inventors

Prior Lake, MN, United States of America

Jon P Zoller