Patent ID: 8614384

Claim:
A keyboard for a musical instrument comprising: a first under-keyboard; and a second under-keyboard; wherein each of said first and second under-keyboards includes at least four parallel and equidistant lines, each line including at least one key, the distance between the lines being identical for both under-keyboards; such that, with respect to a given base key corresponding to a note n located on a line arranged between an adjacent lower line and an adjacent upper line: on the adjacent upper line, there is at least one of an upward-major key and an upward-minor key with respect to the base key, wherein: the upward-major-key actuates the upward major third of n, and is arranged so that the line starting from the base key and passing through the upward-major-key forms a first angle, with the line on which the base key is located; wherein, on the first under-keyboard, the measure of the first angle is M and belongs to the interval [0°, 90°], and on the second under-keyboard, the measure of the first angle is −M; and the upward-minor-key actuates the upward minor third of n, and is arranged so that the line starting from the base key and passing through the upward-minor-key forms a second angle, with the line on which the base key is located; wherein, on the first under-keyboard, the measure of the second angle is m and belongs to the interval [90°, 180°], and on the second under-keyboard, the measure of the second angle is −m; and on the adjacent lower line, there is at least one of a downward-major key and a downward-minor key with respect to the base key, wherein: the downward-major-key actuates the downward major third of n, and is arranged so that the line starting from the base key and passing through the downward-major-key forms a supplementary first angle; wherein, on the first under-keyboard, the measure of the supplementary first angle is M−180°, and on the second under-keyboard, the measure of the supplementary first angle is 180°−M; and the downward-minor-key actuates the downward minor third of n, and is arranged so that the line starting from the base key and passing through the downward-minor-key forms a supplementary second angle; wherein on the first under-keyboard, the supplementary second angle has a measure of m−180°, and on the second under-keyboard, the supplementary second angle has a measure of 180°−m; and for each key actuating a note q on each of the under-keyboards, there exists on the other under-keyboard at least one of: a key actuating the upward major second of the note q; and a key actuating the downward major second of the note q; so that notes are alternatively distributed from one under-keyboard to the other, while being arranged by thirds on each of them.