Patent ID: 7423634

Claim:
A keyboard for a mobile electronic device, comprising: a board, which has a working surface; a number of nodes on said working surface, each with a top surface; a data input platform with electronic circuits which converts a user's finger strikes on said top surface to an electronic signal unique to that node; markings indicating the use of each node over said working surface; structural layers, at least one of which is rigid at least across areas of the working surface which are off the device body when typing; spans between centers and gaps between perimeters of the top surfaces of adjacent nodes that are wide enough to ensure accuracy so that a finger aiming substantially at the center of a node would not activate another; gaps between perimeters of the top surfaces of adjacent nodes are wide enough to ensure accuracy so that a finger striking a node, has a substantially low chance of activating another; said structure covers those traces of the circuit which are underneath the working surface, making said traces unexposed to finger touch; said layers and platform give an actuation force below about 100 grams; said layers are thin such that said board is less than about 2.5 mm thick across said working surface; said layers are light, where across the working surface, each square centimeter is below about 0.5 grams; said thickness and weight limits exclude the thickness of layers and components needed for the device, without said keyboard; and said markings are visible both when the device screen is turned on and off.