US Patent 7012206 Waterproof keyboard

A waterproof keyboard includes a generally flat key panel supporting keytops thereon. Membranes support thereon key contacts and connecting circuits for the contacts, and are supported by a generally flat support base, corresponding in shape to the key panel. Between the membranes and the key panel, a waterproof layer is supported by the support base for sealing the membranes in cooperation with the base. The waterproof layer, made of a sheet of flexible synthetic resin, is pressed with an elongate elastic member against the edge portion of the support base. The key panel is fixed to the support base to cause the waterproof layer and support base to seal the membranes, which will surely be protected from dust and moisture.