US3663738A

US3663738A - Key supporting structure of keyboard musical instruments

Info

Publication number: US3663738A
Application number: US61899A
Authority: US
Inventors: Seizi Nakada
Original assignee: Nippon Gakki Co Ltd
Current assignee: Nippon Gakki Co Ltd
Priority date: 1969-08-07
Filing date: 1970-08-07
Publication date: 1972-05-16
Anticipated expiration: 1989-05-16

Abstract

To improve the key supporting structure of a keyboard musical instrument, there are formed on both sides of the rear bottom plane of a key two opposite grooves extending crosswise of the key with an intermediate partition wall located therebetween, and on the upper edge portion of a key supporting plate there is formed a notch corresponding to the intermediate partition wall between the two grooves. The key is supported on the supporting plate by fitting the intermediate partition wall of the key into the notch of the supporting plate with the upper edge portion of the supporting plate received in the grooves.

Description

United States Patent Nakada [151 3,663,738 [451 May 16,1972

[54] KEY SUPPORTING STRUCTURE OF KEYBOARD MUSICAL INSTRUMENTS 3,087,368 4/1963 Lund ..84/423 3,543,631 12/1970 Ohno ..84/433 Primary Examiner-Stephen J. Tomsky Assistant ExaminerLawrence R. Franklin Attorney-Kemon, Palmer & Estabrook ABSTRACT To improve the key supporting structure of a keyboard musical instrument, there are formed on both sides of the rear bottom plane of a key two opposite grooves extending crosswise of the key with an intermediate partition wall located therebetween, and on the upper edge portion of a key supporting plate there is formed a notch corresponding to the intermediate partition wall between the two grooves. The key is supported on the supporting plate by fitting the intermediate partition wall of the key into the notch of the supporting plate with the upper edge portion of the supporting plate received in the grooves.

5 Claims, 6 Drawing Figures Patented May 16,1972

F I G. 2 I

' (PRIOR ART) (PRIOR ART) 5J4! I I I I I I I I U! I I I INVENTOR.

BACKGROUND OF THE INVENTION The present invention relates to improvements in the key supporting structure of the fulcrum section of the key of a keyboard musical instrument such as an electronic organ.

The prior art key supporting structures of the fulcrum section of the key of keyboard musical instruments are devised as shown in FIGS. 1 and 2.

In FIG. 1, the numeral denotes a key of a keyboard musical instrument such as an electronic organ. The key 10 is ordinarily formed of plastic material. The underside 11 of the rear end portion (opposite to the side depressed by a finger) of the key 10 is provided with a rectangular hole 12 in the middle portion of its width. To the rear end of a keyboard frame 13 is welded a supporting plate 14 so as to rise above the frame 13. On the upper edge 15 of the supporting plate 14 is formed a projection 16 to be inserted into the rectangular hole 12 of the key 10.

There are formed the same number of projections 16 as that of the keys by punching the supporting plate 14 for instance. The projection 16 of the supporting plate 14 is fitted into the hole 12 of the key 10 to constitute the fulcrum section of the key 10.

When the key hole 12 engages the projection 16 of the supporting plate 14, the underside 11 of the key 10 tightly contacts the upper edge 15 of the supporting plate 14 on both sides of the projection 16.

Since the key is loosely fitted in the hole 12, it can rotate about its fulcrum section composed of the projection 16 and hole 12, when depressed at the front end by a finger.

In another prior art structure shown in FIG. 2,- the key 10 has a groove 18 formed on the underside of its rear end portion and extending transversely thereof.

One wall face 19 of the. groove is formed perpendicular to the lower face of the key and the other wall face 20 is somewhat inclined with respect thereto, so that the length of the groove in the longitudinal direction of the key gradually becomes smaller in a vertical direction. On the upper edge 15 of the supporting plate, there are formed projections 16 with a predetermined space therebetween. The space is substantially equal to the width of the key. The projections are formed, for instance, by punching the supporting plate as is the case with the aforementioned structure.

The groove 18 on the underside of the key is fitted into the upper edge 15 between the projections 16 of the supporting plate 15 to form the fulcrum section of the key.

In either of the aforementioned cases, however, it is very difficult to make all the upper edges between the projections of supporting plate exactly flush with each other.

If, in the prior art key supporting structure shown in FIG. 1, the adjacent upper edges 15 lying between the respective projections 16 are not positioned flush, then it will be impossible to arrange the keys in a horizontal plane without causing their upper surfaces to incline either way with respect to the direction of their row.

If, in the prior art key supporting structure shown in FIG. 2, the upper edges 15 of the key supporting plate 14 lying between the projections 16 are not made flush, then the the upper surfaces of the adjacent keys will not be kept in a horizontal plane or will not become flush with each other, namely, the keys will assume stepped positions, even though the upper surface of the individual key may be disposed horizontal.

It is also necessary to make the projections of the supporting plate 14 fully narrow. Especially in the case of the structure shown in FIG. 2, the projection should have as small a width as about 0.8 mm from the standpoint of reducing as much as possible the clearance between the adjacent keys. However, it is difficult for the present day manufacturing technique to form projections of such small width with sufficient accuracy.

SUMMARY OF THE INVENTION Accordingly, the object of the present invention is to eliminate the above-mentioneddrawbacks and provide a key supporting structure for a keyboard musical instrument which permits easy fabrication and the flush arrangement of keys.

According to an aspect of this invention, there is provided a key supporting structure for a keyboard musical instrument which comprises a key of substantially rectangular cross section having a pair of grooves formed on the underside thereof and arranged in a transverse direction thereof and an intermediate partition wall located between said pair of grooves and defining said grooves; and a key supporting plate having a notch formed on the upper edge thereof, whereby said intermediate partition wall is fitted in said notch with the upper edge of said key supporting plate received in said pair of grooves.

BRIEF EXPLANATION OF THE DRAWING FIGS. 1 and 2 are exploded fragmentary perspective views showing schematically the key supporting structures of prior art keyboard musical instruments;

FIG. 3 is a cross-sectional view of a key supporting structure according to an embodiment of the present invention and its related mechanisms, where the central part of the key is seetioned lengthwise;

FIG. 4 is an exploded fragmentary perspective view for better understanding of the key supporting structure as shown in FIG. 3;

FIG. 5 is an enlarged cross-sectional view along the line V V ofFIG. 3; and

FIG. 6 is an enlarged cross-sectional view along the line VI-VI ofFIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT There will now be described by reference to FIG. 3 a key supporting structure and its related mechanism practically employed in, for example, an electronic organ. The reference numeral 10 denotes a key of substantially rectangular cross section formed of plastics. The key 10 is supported by a key supporting plate 14 of metal or other suitable materials at the underside 11 of the rear portion, the supporting structure of the supporting plate 14 being later described in detail. The supporting plate 14 is welded to the rear portion of a keyboard frame 13, extending in a vertical direction. Between the upper face 17 of the end portion of the key 10 and one end portion of the supporting plate 14 is stretched a tension spring 21 enabling the key 10 to be normally kept horizontal except when the front end portion of the" key 10 is depressed by a finger. There is bored a hole 22 near that part of the keyboard 7 frame 13 which faces the front end portion of the key 10. Through this hole 22 is inserted a member 23 fixed by a proper means to the key 10 so as to limit the upward movement of the key 10. There are further fitted buffer members 24 and 25 of felt respectively on that part of the underside of the keyboard frame 13 facing the member 23 and on that part of the upper face of the frame 13 facing the front part of the key 10, thereby moderating impacts on the key 10 when it is depressed or released.

The mechanisms involved in a keyboard musical instrument other than the key supporting structure of the present invention consisting of the key 10 and key supporting plate 14 shown in FIG. 3 are identical with those of the prior art. The same parts of FIGS. 3 to 6 as those of FIGS. 1 and 2 are indicated by the same numerals.

Referring to FIG. 4, there are formed at the prescribed parts of the rear underside ll of the key 10 a pair of

grooves

27 and 28 arranged or aligned in a transverse direction of the key 10. Each

groove

27 or 28 extends in a crosswise direction of the key 10 with one end thereof terminating in the plane of the

upright side wall

29 or 30 of the key 10. Between the

grooves

27 and 28 is located an intermediate partition wall 26 defining the other ends of the

grooves

27 and 28.

The

opposite walls

31 and 32 of the intennediate partition wall 26 are formed perpendicular to the underside 11 of the rear portion of the key as shown in FIG. 5. The

opposite side walls

33 and 34 of the groove extend in the transverse direction of the key 10 and are inclined in opposite directions to each other, as apparent from FIG. 6, so that the width of the

grooves

27 and 28 grows smaller toward the top end face 35 thereof until the width of the face 35 becomes substantially equal to the thickness of the upper edge of the supporting plate 14. The top end faces 35 of the both grooves are formed flush. This is easily accomplished by molding the key from plastics material. On the flush upper edge 15 of the key supporting plate 14 there are formed spatially, for example, by punching, the same number of notches 36 as that of the keys involved.

The notch 36 has a width slightly larger than that of the aforesaid intermediate partition wall 26 between the

grooves

27 and 28, with the

opposite walls

37 and 38 of the notch 36 positioned perpendicular to the upper edge 15. The notch 36 of the supporting plate 14 has a depth greater than the height of the intermediate partition wall 26 measured from the top end face 35 to the lowest end of the wall.

The key supporting plate 14 constructed as described above enables the key 10 to be supported by the supporting plate 14 by fitting the intermediate partition wall 26 into the notch 36 of the supporting plate 14.

In this case, the key 10 is placed on the upper edge portion 15 of the supporting plate 14 as shown in FIGS. 5 and 6 by causing the upper edge portion 15 of the supporting plate 14 to be received by the

grooves

27 and 28 of the key 10 and to be contacted by the top end face 35. Since both

sides

33 and 34 of the

groove

27 or 28 are inclined, the key 10 can freely rotate about the supporting plate 14 upon depression of the front end of the key 10 with a finger.

As mentioned above, the key supporting structure according to this invention is constructed by a key having at its rear underside a pair of grooves extending crosswise thereof and a prescribed intermediate partition wall located therebetween, and a key supporting plate having its upper edge machined in a straight line and a notch on its upper edge. Accordingly, the

key is kept in a horizontal position without the inclination in either way of its upper surface, simply by fitting the intermediate partition wall into the notch. Further with respect to the notch, the key supporting structure of the present invention eliminates the necessity of applying such precision work as required in the prior art. Moreover the present key supporting structure involves narrow notches instead of narrow projections formed on the upper edge of the key supporting plate as used in the conventional structure, thereby permitting easy manufacture in good yield.

What is claimed is:

l. A key supporting structure for a keyboard musical instrument which comprises a key of substantially rectangular cross section having a pair of grooves formed on the underside thereof and arranged in a transverse direction thereof and an intermediate partition wall located between said pair of grooves and defining said grooves; and a key supporting plate having a notch formed on the upper edge thereof, whereby said intermediate partition wall is fitted in said notch with the upper edge of said key supporting plate received in said pair of grooves.

2. The key supporting structure according to claim 1 wherein said key has opposite upright side walls, and each of said grooves has one end terminating in the plane of the corresponding upright side wall.

3. The key supporting structure according to claim 1 wherein each of said grooves has a top end face contacting the upper edge of said key supporting plate, and said notch has a depth greater than the height of said intermediate partition wall measured from said top end face to the lowest end of said intermediate partition wall.

4. The key supporting structure according to claim 1 wherein each of said grooves has a top end face contacting the upper edge of said key supporting plate, and has opposite side wa ls extending in the transverse direction of said key and inclined in opposite directions to each other so that the width of said groove becomes narrower toward said top end face.

5. The key supporting structure according to claim 1 wherein said key having said grooves and said intermediate partition wall is integrately molded of plastic material.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent NO. 3,663,738 Dated y 16, 1972 Inventor(s) SeiZi Nakada It certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

' Assignee: Nippon Gakki Sugo Kabushiki Kaisha Replace with:

v Nippon Gakki Seizo Kabushiki Kaisha Signed and sealed this 10th day of October 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesti'ng Officer Commissioner of Patents FORM PO-105 uscoMM-Dc 6O376-P69 U.S GOVERNMENT PRINTING OFFICE: I969 0-366-334 UNITED STA ES PATENT oT'TTcE CENFICATE 0F CORREUHN Patent No. 3 a 663 738 Dated May 16, 1972 lnventofls) Seizi Nakada It iscertified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Assignee: Nippon Gakki Sugo Kabushiki Kaisha Replace with:

Nippon Gakki Seizo Kabushiki Kaisha Signed and sealed this 10th day of October 1972..

( SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM PO-105O (10-69) USCOMM-DC 6O375-P69 U.5. GOVERNMENT PRINTING OFFICE: I969 0-365-334

Claims

1. A key supporting structure for a keyboard musical instrument which comprises a key of substantially rectangular cross section having a pair of grooves formed on the underside therEof and arranged in a transverse direction thereof and an intermediate partition wall located between said pair of grooves and defining said grooves; and a key supporting plate having a notch formed on the upper edge thereof, whereby said intermediate partition wall is fitted in said notch with the upper edge of said key supporting plate received in said pair of grooves.

4. The key supporting structure according to claim 1 wherein each of said grooves has a top end face contacting the upper edge of said key supporting plate, and has opposite side walls extending in the transverse direction of said key and inclined in opposite directions to each other so that the width of said groove becomes narrower toward said top end face.