Patent ID: 6894211

Claim:
A keyboard apparatus comprising: a plurality of keys arranged in a row; four frames each having part of said keys arranged thereon, said four frames including three frames for lower tone ranges; four keyboard units each having part of said plurality of keys integrally formed thereon and covering a predetermined tone range, said four keyboard units being arranged above said four frames, respectively; and connecting means connecting adjacent pairs of said four frames in a manner allowing each adjacent pair to be pivoted relative to each other from a folded state to a flat unfolded state, whereby said four frames are allowed by said connecting means to assume a folded position in which said four frames are folded into a size substantially as large as a size of one frame, and a flat unfolded position in which said four frames are unfolded and extend serially in a direction of the row of said keys, wherein said keys include four white keys arranged on said three frames for the lower tone ranges, wherein said four frames includes one frame for a highest tone range, and wherein said one frame has at least two white keys arranged thereon, wherein said one frame has at least one operating element other than said keys arranged thereon, and wherein two of said keyboard units at laterally opposite ends of the keyboard apparatus are slidable relative to the frames associated therewith when said four frames are being folded or unfolded.