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Publication numberUS1603676 A
Publication typeGrant
Publication dateOct 19, 1926
Filing dateJan 13, 1925
Priority dateMar 17, 1924
Publication numberUS 1603676 A, US 1603676A, US-A-1603676, US1603676 A, US1603676A
InventorsForster Franz August Gerhard
Original AssigneeForster Franz August Gerhard
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Piano having quarter tones
US 1603676 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

Oct. 19 1 926.

F. A. G. FJ'RsTER PIANO HAVING QUARTER TONES Filed Jan. 13, 1925 N V E. N T OR: Franz A i/91x7 ema Far s ATT oRNEYf Patented Oct. 19, 1926.




Application filed January 13-, 1925, Serial No. 2,084, and in Germany March 17, 1924.

This invention relates to a novel piano having quarter tones and consists essentially therein that the key-board is composed of three full key-boards of which the lower key-board contains the full tones, while the middle key-board is somewhat displaced with regard to the lower key-board and contains the quarter tones, the upper key-board representing a short repetition of the lower key-board, the keys of which are in mechanical connection with the keys of the lower key-board.

This invention consists furthermore in the employment of a double sounding board, which by special means is so compensated that the vibrations of the individual boards are brought into unison.

lVit-h quarter tone keyed instruments is known to employ key-boards, in which the quarter tones are inserted between the half tone keys by having the width of all keys madeof a reduced size. A key-board of this kind, which is Obtained from a normal key-board by vertically subdividing the same is difficult to play on account of the small width of all keys.

Furthermore, there are key-boards in which the quarter tone keys are positioned in a plurality of closed strips placed horizont-ally between the keys of the half tones. By this arrangement the vertical playing depth of all rows of keys is diminished in such a way, that with hands of medium size it is not possible to strike a greater accord upon one strip of keys. If an attempt were made to reach several tones of the same accord upon a row of keys which is placed further in the rear, it would be found that the playing is unsatisfactory because the ordinary hand could not bridge the intermediate row 'of keys. Consequently it becomes necessary to discard altogether the system of a purality of rows of keys with a small depth of play and to dispose the rows of keys so that the front row will comprise in the usual manner the full and the half tones, while a second row is placed somewhat higher than and in the" rear of said front row, the second row containing the quarter tones and a third row of keys disposed still higher and in the rear of said second row, said third row representing a shortened duplicate of the lower first row of'keys.

From reasons which are connected with the playing of the instrument, it will be desirable to always place the rear playing surface higherthan the front surface to an extent as would correspond in normal keyboards to the dilference in the height between white and black keys. By this it will be necessary to reduce as much as possible the difference in height within the same row of keys, which contains all tones in even width and in chromatic sequence,

Since it will frequently be impossible to move the inner fingers of the hand from the middle row of keys for the quartertones towards the lower row containing the normal keys, there is further arranged a third. strip of keys in the rear and above the strip of the keys for the quarter tones, whose keys may be rigidly connected with the appertaining lower normal keys. In this case, the connections will pass through the intermediate spaces of the strip of keys for the quarter tones and may for instance consist of two strong pins of iron wire and a screw for the tightening of the same. The wire pins are provided at their upper ends with a right-hand thread and at their lower ends with a left-hand thread and are furthermore provided with a proper out With the appertaining lower normal keys or their mechanisms. The quarter tone keys, winch are constructed as levers with a single arm, are positioned in the rear within caps, while the lower keys for the full tones and the half tones are positioned upon scale-beams and bent at their front end in upward direction in order to at--' tain the necessary difierencein the height between the two rows of keys. All keys are towards above shaped obliquely, such as is the case in the upper tones of normal instruments. 7

Since the key-board. in which the white and black keys are of even length, would offer to the eye a somewhat confusing picture, it will "be necessary to retain in some form the enlargement of the white keys which is present in the usual key-boards in front of the black keys. In the rear row of keys for reasons connected with the playing this will not be desirable, it will. however be possible at the front and middle row of keys. In this case, for technical reasons. the usual width of the strip of the keys is somewhat reduced.


The key-board is shown diagrammatically in a top-view in Fig. 1 and in F g. 2 n a side view. Fig. 3 shows a mod fied form of.

the piano according to this invention-em ploying a double sounding board and means for compensating the sound differences of the two partgthereof. In the first row the keys 1 will give the full tones and 2 the half tones and upon the middle key-board the keys 3 and 4 will represent the quarter-tones while upon the upper key-board the keys 5 and-6 will correspond to the lowermost-keys '1 and 2. Y s

In this key-board there have been used in every case two acoustically independent sounding boards, of'which one serves for the transmission of the full'and half tones, the other for thetra-nsmission of the :quarter tones to the audience. It is known, that in spite of most careful manufacture} two in struments will always be different from each other in their individual tones, -'a featu re, which for the present case is most undesirable. t will therefore be necessary to bring a the vibrating parts, that is to say the sound ing boards, in intimate mechanical connection with each other.

The most suitable basis for a construction of this kind is found in the double sounding board, in which, asknown the two individual boards are connected by having the vi-.

brations' of the upper bridge transmitted through a third bridge positioned between both sounding boards uponthe lower board and vice versa. The vibrations of the lower bridge will also be transmitted'upon the upper board.

Double sounding boards 1 have heretofore been used in many variations with the purpose to increasethe-strength of the tone of.

a normal piano. Since, however, the sounding board "represents a 'in-ass expandingin the manner of a surface, and accordingly;

will be set into forced vibrations byan in)- pulse of fixed strength, an augmentation of this mass with thestrength of the impulse remaining the same, willnevercause to augment the vibrations-in its entirety, but the excitingiinpulse will distribute itself upon both surfaces, so that they will swing with one half of the energy. The rare use of double sounding boards in'aetual practice is a proof for this.

The present invention, which consists in the employment of a so-called double sounding board for the construction of a -grand piano with quarter tones, has therefore not for its purpose to increase the strength of the tone, but to bring about a compensation of then'onna'll' occurring differences in the sounds, given by the two sounding boards. This is attained by exciting both sounding boards uniformly during the striking of a half tone as well as of a quarter tone.

In Fig. 3, 7 represents the sounding heart for the quarter tones and .8 the sounding board for the half, tones, the arch of the latter and arrangement of the ribs being opposed to the upper sounding board. and 10 designate the appertaining lateral bridges whi-lell represents the'intermediale bridge effecting the transmission, bridge being-eventually provided with openings. 12 and 13 designate the two iron frames, which carry the strings of the instrument, either of said frames representing the reflected image of theother;


1. In a quarter tone piano the 'combina tion of three fullgkey-boardsarranged one above the other, the lowerof said keyboards containing the full tones and the semitones, the middle being somewhat, displaced against the lower board and containing the quarter tones, and the upper keyboard representing a short repetition of the lower key-board, with mechanical means for interconnecting the keys of the'upperwith those ofthe lower board. c

2. A quarter tone =piano coniprising three full key-boards arranged one above the other,tl1e lower of said keyboards containing the full tones and the semitones, the

middle board being displaced against the lower board I and containing the quarter tones, while the upper-board represents a short repetition vof thelower keygboard, said two upper key boards having all keys of even length and the full tone keys of the lowermost key board projecting only rela tively little above the keys, for the semitones, and. means for lnterconnecting the ke s of the key-board with-those of the lower board. v

3. A quarter tone piano according to claim 1, havin two soundingboards, which are connected by a bridge for compensateup the tone differences of the two sounding boards. In testimony whereof I aflixed my signature.



Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3012460 *Jun 25, 1958Dec 12, 1961Wilson Ervin MMusical instrument
US3915050 *Mar 21, 1974Oct 28, 1975Wajiha Abdel HakKeyboard instrument
US4628792 *May 24, 1985Dec 16, 1986Keast Lawrence JModified musical instrument keyboard
US4658695 *Sep 17, 1985Apr 21, 1987Cutler Douglas AMulti-decked keyboard for musical instruments
US5874685 *Aug 15, 1997Feb 23, 1999Ellis; James F.Reduction of longitudinal modes in musical instruments strings
US20060283313 *Jun 16, 2006Dec 21, 2006Basralian Peter HSystem and method for middle c and lower string tone enhancement for an acoustical piano
WO2011062566A1 *Oct 15, 2010May 26, 2011Zulfikar Yavuz OzerNovelty in keyed and stringed music instruments
U.S. Classification84/451
International ClassificationG10C3/12
Cooperative ClassificationG10C3/12
European ClassificationG10C3/12