| 20090135030 | Uniquely identifiable keys for electronic keyboards - An electronic keyboard including a plurality of keys arranged as a matrix, each key including a plunger, and a conductive element on the bottom of the plunger, the conductive element having a characteristic resistance, an electronic circuit having an input current source, and mounted on a surface beneath the plurality of keys such that when a key is pressed its conductive element closes a switch in the circuit, an analog-to-digital convertor for converting an output voltage of the circuit to a digital signal, and a controller for determining from the digital signal when a key is pressed, and for identifying the key that is pressed. | 05-28-2009 |
