The Jankó keyboard is a musical keyboard layout for a piano designed by Paul von Jankó in 1882. It was designed to overcome two limitations on the traditional piano keyboard: the large-scale geometry of the keys (stretching beyond a ninth, or even an octave, can be difficult or impossible for pianists with small hands), and the fact that each scale has to be fingered differently. Instead of a single row, the Jankó keyboard has an array of keys consisting of two interlocking manuals with three touch-points for each key lever. Each vertical column of keys is a semitone away from its neighboring columns, and on each horizontal row of keys the interval from one note to the next is a whole step.
This key layout results in each chord and scale having the same shape on the keyboard with the same fingerings regardless of key, so there is no change in geometry when transposing music. The configuration retains the colouring of traditional keyboards (white naturals, black sharps and flats) for pedagogical purposes.
For an 88-note (full size) keyboard, there would be 264 keys in total, with each note playable by three keys in vertical alignment. In the picture above, the white keys have been coloured to show how the keys are interconnected. Instead of 123 cm (48 in) the keyboard is only 89 cm (35 in) wide, and the smaller key size allows reaching wider intervals.
The Jankó keyboard never achieved wide popularity. Music educators were not convinced that the benefits of the new keyboard were enough to challenge the traditional keyboard. Few performers were prepared to relearn their repertoire on a new keyboard with entirely different fingering. Both reasons left keyboard manufacturers afraid to invest in a redesigned keyboard which promised to have only marginal commercial success.
Many embodiments of this keyboard have appeared since its conception. Jankó himself (in German patent 25852, dated 14 January 1884) originally chose a key shape which resembled the slim, black keys on the familiar piano keyboard. A year later (in German patent 32138, dated 1 July 1885) the keys became wider and shorter. Other inventors have filed patents for keyboards which are substantially similar to his design, differing most often in key shape or instrument to which those keyboards are affixed. (For example: John Trotter English Patent 3404, 4 March 1811, William A. B. Lunn devised in 1843 under the name of Arthur Wallbridge a sequential keyboard with two parallel rows of keys, each in whole tones. Miguel Theodore de Folly, 1845,Useful Registered Design Number 448 for a geometrical keyboard for the pianoforte, Gould and Marsh , Edgar , Cramer , McChesney , Stewart , Adams , Nordbö , Barnett , Reuther , and Firestone .) The most recent patents are for MIDI compatible instruments.