US3643539A

US3643539A - Tone-balancing rib member

Info

Publication number: US3643539A
Application number: US41977A
Authority: US
Inventors: Clifford W Andersen
Original assignee: Wurlitzer Co
Current assignee: TWCA CORP
Priority date: 1970-06-01
Filing date: 1970-06-01
Publication date: 1972-02-22
Anticipated expiration: 1989-02-22

Abstract

A laminated piano soundboard includes a treble and bass bridge for transmitting vibrations from the piano strings and a plurality of spaced-apart ribs for localizing the vibrations at the center, prime resonating area of the soundboard. Since the laminated character of the soundboard tends to inhibit localization thereby adversely affecting its tonal quality, carefully sized and shaped weakened areas are provided in certain preselected ones of said plurality of rib members for assuring enhanced resonance.

Description

United States Patent [151 3,643,539 Andersen 1 Feb. 22, 1972 [54] TONE-BALANCING RIB MEMBER FOREIGN PATENTS 0R APPLICATIONS [72] Inventor: Clifford W. Andersen, DeKalb, 111. 646,229 1 1/1928 France ..84/ 195 [73] Assignee: The Wurlitzer Company, Chicago, 111. Primary Examiner Richard B Wilkinson [22] Filed: June 1, 1970 Assistant Examiner--Lawrence R. Franklin Attorney-Olson, Trexler, Wolters & Bushnell [21] Appl. No.: 41,977

- [57] ABSTRACT [52] U.S.Cl ..84/l95 A laminated piano soundboard includes a treble and bass [51] Int. Cl.... ..Gl0c 3/06 bridge for transmitting vibrations from the piano strings and a [58] Field of Search ..84/194-l96 plurality of spaced-apart ribs for localizing the vibrations at the center, prime resonating area of the soundboard. Since the [56] References Cited laminated character of the soundboard tends to inhibit localization thereby adversely affecting its tonal quality, care- UNTTED STATES PATENTS fully sized and shaped weakened areas are provided in certain preselected ones of said plurality of rib members for assuring 3,513,745 5/1970 Tansky ..84/ 195 enhanced resonance" 3,086,420 4/1963 Yamamoto. .....84/ 195 3,477,330 11/1969 Bert .....84/193 7 Claims, 6 Drawing Figures TONE-BALANCING RIB MEMBER SUMMARY OF THE INVENTION This invention relates generally to piano soundboards and more particularly to individual components of a piano soundboard for enhancing the tonal quality thereof.

DISTINCTION OVER THE PRIOR ART AND OBJECTS A piano soundboard is a resonator to which the vibrations of piano strings are transmitted for producing tonal qualities. In the past, such soundboards were made out of solid boards which were selectively tapered and provided with transversely extending rib members for localizing the vibrations in a manner which would most enhance the tonal qualities. More recently, some pianos have utilized laminated rather than solid soundboards. However, it has been found to be impossible to satisfactorily taper a laminated board. Therefore, in the past, such laminated soundboards were characterized by poor tonal qualities.

Accordingly, a general object of the present invention is to provide a new and improved laminated soundboard which is characterized by greater tonal qualities than those of the prior art.

Another object of the present invention is to provide a laminated soundboard which vibrates in a controlled fashion.

A more particular object of the present invention is to provide a plurality of novel sculptured rib members to be used with a laminated soundboard for controlling the standing sound waves thereof.

Yet a more particular object of the present invention is to provide a plurality of sculptured rib members which cause the standing sound waves of a soundboard to localize in the center of the soundboard.

These and other objects and features of the invention will become more apparent from a reading of the following descriptions.

The above objects are achieved and the disadvantages of the prior art are eliminated by providing a piano soundboard comprising a laminated resonating board which is preferably made from three-ply mahogany and which is coupled to the strings of a piano through a treble bridge and a bass bridge. A plurality of ribs are mounted on the back side of the resonating board and include selective ones which are appropriately weakened or relieved for causing the standing sound waves of the board to localize in a manner most effective for producing the highest tonal quality.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. I is a front elevational view of a soundboard constructed according to the invention;

FIG. 2 is a front elevational view of the soundboard of FIG. I coupled to the piano strings of an upright piano;

FIG. 3 is a back elevational view of the soundboard and piano of FIG. 2, particularly showing a plurality of ribs mounted thereto;

FIG. 4 is a blown up and broken partial sectional view taken along line 4-4 in FIG. 3;

FIG. 5 is a blown up and broken partial sectional view taken along line 55 in FIG. 3; and

FIG. 6 is a blown up and broken partial sectional view taken along line 66 in FIG. 3.

DETAILED DESCRIPTION Referring now in detail to the drawings, specifically to FIG. I, a piano soundboard constructed in accordance with the present invention is indicated generally by the reference numeral 10. The soundboard comprises a substantially rectangular laminated resonator board 12 which is preferably fashioned from three plys of mahogany wood and which is coupled, through a treble bridge 14 and bass bridge 16, to the vibrating strings of a piano for transmitting a series of vibrations to the board I2-and thereby producing standing sound waves. A plurality of longitudinal rib members 18a through 181', positioned on selected areas of the back side of the resonator board, provide rigidity to those areas so that the remaining surface thereof may freely vibrate for most advantageously localizing the standing sound waves. The bridges and rib members are preferably mounted to the resonator board by a resinous plastic waterproof glue so that the board is not impregnated with moisture. Such moisture has been sound to reduce the tonal quality of a soundboard.

The surface of resonator board I2 is selectively tapered in the same manner as the prior art solid boards, but due to their laminated characteristic, the various tapered sections do not exhibit a predictable quality of sound which is otherwise found in solid resonator boards. In this regard, it has been found that a plurality of conventional rib members alone, do not properly localize the standing sound waves. Accordingly, rib member 18d, which extends substantially through the center of the resonator board and adjacent rib members and I8b, include carefully sized and shaped weakened or relieved areas 20d, 20c and 20b respectively which cause the standing sound waves to localize at the center of resonator board 12 where they have been found to produce the best tonal quality.

Turning to FIG. 2, an upright piano 22 utilizing the soundboard 10 includes a vertically mounted substantially rectangular housing or frame 24 supporting the soundboard so that the treble and bass bridges extend out beyond the frame for engagement with the vibrating portions of a plurality of treble strings 26 and bass strings 28 respectively.

The treble strings, which are connected to the top of frame 24 by a plurality of string pins 30, extend down and slightly to the left, as viewed in FIG. 2, so as to pass over and engage the treble bridge 14 and thereafter terminate at a bridge 32 which is mounted to the bottom and one side of the frame and which extends across the soundboard slightly below the treble bridge. A plurality of string pins 31 secure the strings to the bridge 32. The bass strings 28, which are connected to the top of frame 24 by string pins 34, extend downward, slightly to the right and over the treble strings for engagement with the bass bridge 16 and are thereafter secured to the bottom of the frame by a group of string pins 36.

Vibrations are conventionally imparted to the strings by an action mechanism (not shown) which is actuated by a corresponding key of the piano keyboard. These vibrations, which include differing harmonic frequencies depending upon the length, diameter, tension and density of the strings, are transmitted to the resonator board through the bridges and develop a standing sound wave. Both the plurality of rib members generally and the weakened or relieved rib members .1 8b, 180 and 18d specifically provide localization, so that the sound waves produce an enhanced tone.

Referring now to FIG. 3, the rib members 180 through l8i are equally laterally spaced on the back of resonator board I2 and are aligned substantially perpendicularly to a line which bisects the upper left and lower right-hand corners of the board, as viewed in FIG. 3. The rib members are of varying length so as to extend substantially from one edge of the board to the other, the members being relieved on common ends to form respective beveled shoulders 38a through 381' which are sized in accordance with their respective positions on the resonating board to constrain or localize the transmitted vibrations in areas designated by the reference numeral 40 which lie therebetween. Each of the members tapers downward, at a slight angle, from the uppermost point of its shoulder so that a beveled shoulder may be eliminated at the other end.

As stated above, the rib members, when constructed in the aforementioned manner, do not alone localize the vibrations in the desired fashion. Absent the weakened or relieved areas in

members

18b, 18c and 18d, there would be a tendency for most of the vibration to develop at the upper right-hand corner of the board as viewed in FIG. 3.

It should be noted that three of the four vertices of frame 24 include integrally connected triangular extensions or supports 42 which convert the effective resonating area from a rectangular to a hexagonal area. This, in turn, further directs the vibrations to the center.

Referring to FIGS. 4 through 6, each of the weakened or relieved areas b, 20c and 20d of

respective rib members

18b, 18c and 18d comprises a pair of longitudinally spaced beveled shoulders 44!), 44c and 44d which join a respective substantially flat elongated surface portion 46b, 46c and 46d, flat portion 46c being of greater length than the fiat portion 46d, and the fiat portion 46b being of greater length than the flat portion 460. While the rib members are preferably sculptured so as to form these weakened areas, it is to be understood that any suitable method of achieving the same results is contemplated by the invention.

With the rib members constructed and positioned in the aforesaid manner, the weakened areas of

rib members

18b, 18c and 18d redirect the vibrations of the resonator board and therefore the standing sound waves to substantially the center of the resonator board which, as stated above, produces the best tonal quality.

While particular embodiments of the invention have been shown, it should be understood, of course, that the invention is not limited thereto since many modifications may be made. It is, therefore, contemplated to cover by the present application any such modifications as fall within the true spirit and scope of the appended claims.

I claim:

1. A piano soundboard assembly comprising: a laminated resonator board for producing standing sound waves; bridge means mounted to one side of said resonator board for coupling strings of a piano to said resonator board for developing said standing sound waves; and a plurality of laterally spaced, elongated rib members mounted to said resonator board, selected, generally medially disposed ones of said plurality of rib members including weakened areas for aiding in the directional control of said standing sound waves whereby to enhance the tonal quality of said soundboard, each of said weakened areas comprising a pair of longitudinally spaced shoulders disposed intermediate the ends of said rib members transverse thereof and an elongated recessed portion between said shoulders for directing said sound waves substantially to the center of said resonator board.

2. A piano soundboard assembly according to claim 1 wherein said selected rib members having weakened areas in clude three adjacent rib members positioned intermediate the remaining rib members. f

r 3. A piano soundboard assembly according to claim 2 wherein each of said recessed portions is substantially flat.

4. A piano soundboard assembly according to claim 3 wherein said resonator board is substantially rectangular in shape for defining a substantially similarly shaped resonating surface area, and wherein said rib members are positioned at equal acute angles with respect to a given edge of said resonator board.

5. A piano soundboard assembly according to claim 4 wherein said plurality of rib members includes nine rib members, one rib member being positioned on one side of said selected rib members and five rib members being positioned on the opposite side of said selected rib members.

6. A piano soundboard assembly according to claim 5 wherein the selected rib member positioned adjacent said five rib members extends substantially through the center of said resonator board, the flat recessed portion of the last mentioned selected rib member being of shorter length than the flat recessed portion of each of the other two selected rib members, and wherein the flat recessed portion of the selected rib member positioned adjacent said one rib member is of greater length than the flat recessed portion of said intermediate selected rib member.

7. A piano soundboard assembly according to claim 6 wherein said resonator board includes su port means mounted to three of its four vertices and adapte for connecting said resonator board to a piano, said support means converting a substantially rectangular resonating surface area of said resonator board to a substantially hexagonal resonating surface area.

Claims

2. A piano soundboard assembly according to claim 1 wherein said selected rib members having weakened areas include three adjacent rib members positioned intermediate the remaining rib members.

3. A piano soundboard assembly according to claim 2 wherein each of said recessed portions is substantially flat.

7. A piano soundboard assembly according to claim 6 wherein said resonator board includes support means mounted to three of its four vertices and adapted for connecting said resonator board to a piano, said support means converting a substantially rectangular resonating surface area of said resonator board to a substantially hexagonal resonating surface area.