Keypad device

Abstract

A keypad device for a mobile telephone or other device utilizing a keypad or keyboard is comprised of a flexible substrate and a keypad cover. The flexible substrate includes a plurality of keys affixed to the surface as well as a plurality first conductive strips associated with each key. The keypad cover is attached to the flexible substrate. The keypad cover typically includes holes that permit the plurality of keys to protrude through the keypad cover. In addition, the keypad cover further includes a plurality of second conductive strips that selectively contact a corresponding first conductive strip on the flexible substrate. The plurality of first conductive strips is coupled to ground and the plurality of second conductive strips is coupled to logic circuitry. Or, in another embodiment, both sets of conductive strips are coupled with the logic circuitry. The default position of the keypad device has each of the first conductive strips in contact with each of the corresponding second conductive strips. This creates a short circuit condition that prevents key signals from being received by the logic circuitry. When a particular key is depressed to the point where the first conductive strip associated with that particular key is separated from the second conductive strip corresponding to the first conductive strip, the short circuit condition is removed. This allows a signal to be transmitted to and processed by the logic circuitry indicating that a particular key has been selected.