Elastomeric key switch actuator

A resilient key switch assembly comprising:

• An electrical switch including two annular shaped normally open contacts of the same diameter;
• and
• A hollow closed topped dome shaped cover made of elastically resilient material, the cover having and open bottom end situated opposite the closed top, the cover overlaying the electrical switch with its open bottom end in surrounding relationship with the contacts of the switch, the cover including a first linear wall portion shaped to undergo a rolling action during compression displacement of the cover toward the contacts and to undergo an unrolling action during expansion displacement of the cover away from the contacts, the cover further including a second tactile wall located closer to the open bottom end than the linear wall portion, the tactile wall portion being shaped to undergo a buckling action toward the switch at a predetermined compression displacement and to undergo an unbuckling action away from the contacts at a predetermined expansion displacement that is smaller in total displacement than the predetermined compression displacement, the cover also including an annular shaped foot having substantially the same diameter as the contacts and in aligned relationship with them ,the foot being positioned within the cover to close the contacts at the buckling action of the second portion and to open the contacts at the unbuckling action of the second portion.