Abstract: Disclosed is a keypad for use with compact and portable cellular telephone systems in which each key is backlit. A partially translucent overlay layer of flexible material includes a raised key. Under the key, in a preferred embodiment, is an actuation layer, which, during operation, is depressed downward by the key. Below the actuation layer, is a tactile feedback layer including a dome for each key, in which, after being depressed to a predetermined degree, the dome inverts causing a conductor located below the dome to short conductive traces on a substrate upon which the keypad is mounted. In a preferred embodiment, the keys are backlit by a light source extending through the substrate upon which the keypad is mounted. The tactile feedback layer includes a structure for reducing pressure on the light source when the tactile layer is in the inverted condition, resulting in a thinner keypad with a brighter backlit key and a longer life light source.

Abstract: Disclosed is a keypad for use with compact and portable cellular telephone systems in which each key is backlit. A partially translucent overlay layer of flexible material includes a raised key. Under the key, in a preferred embodiment, is an actuation layer, which, during operation is depressed downward by the key. Below the actuation layer, is a tactile feedback layer including a dome for each key, in which, after being depressed to a predetermined degree, the dome inverts causing a conductor located below the dome to short conductive traces on a substrate upon which the keypad is mounted. In a preferred embodiment, the keys are backlit by a light source extending through the substrate upon which the keypad is mounted. The tactile feedback layer includes a structure for reducing pressure on the light source when the tactile layer is in the inverted condition, resulting in a thinner keypad with a brighter backlit key and a longer life light source.

Abstract: A membrane keyboard is comprised of a dielectric substrate and an overlying deflectable membrane layer separated by a spacer. A plurality of contact poles are located on the dielectric substrate with an electrically conductive common contact area located on the flexible membrane. A portion of the flexible membrane is locally stiffened and, in a preferred embodiment, provided with a ridge extending away from a portion of the membrane towards the contact poles. Upon actuation of the switch, the stiffened portion of the membrane ensures simultaneity of contact between the common contact area on the membrane and the contact poles on the substrate. Preferred embodiments utilize a generally circular ridge in the deflectable membrane cooperating with interdigitated contact poles.