Music – Instruments – Stringed
Patent
1995-08-24
1997-06-03
Spyrou, Cassandra C.
Music
Instruments
Stringed
84423R, 312295, 220334, G10C 302
Patent
active
056356552
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to an apparatus, with an oil damper, for opening and closing a fall board of a musical keyboard instrument.
2. Background Art
As a conventional apparatus for opening and closing a fall board of a musical keyboard instrument, there are known some in which a damping function is generated and the fall board rotates gently when it is rotated in a direction to close it so that a shock to be applied to fingers, etc. may be alleviated even if the fingers, etc. were to be pinched between the fall board and the musical instrument main body by inadvertently letting a fall board to fall. One such apparatus uses a spring damper having wound a coil spring around a rotation shaft, and another apparatus uses an oil damper.
DISCLOSURE OF INVENTION
With the above-mentioned apparatus using the spring damper, there are disadvantages in that, even in a condition in which the fall board is closed, the fall board is slightly lifted due to the elastic force of the spring and is therefore not tightly closed. Thus it is difficult to stabilize the quality by controlling the spring constants. With the above-mentioned apparatus, using the oil damper, there are disadvantages in that, because the damper is large in size, it is embedded in the musical instrument main body. Therefore the musical instrument main bodies cannot economically be used in common with the musical instrument main bodies provided with fall boards requiring no damper function. Thus, the cost cannot be reduced.
The present invention has an object of solving disadvantages of the conventional apparatuses.
In order to attain the above-mentioned object, the present invention is characterized in: that an oil damper is provided in a fall board so that the fall board is rotatably supported on a musical instrument main body by the oil damper. Such oil damper creates a damping function when the fall board rotates in a direction in which it is closed.
Further, the present invention is characterized in that, in an apparatus for opening and closing a fall board of a musical keyboard instrument in which an oil damper is provided in the fall board so that the fall board is rotatably supported on a musical instrument main body by the oil damper and in which the oil damper creates a damping function when the fall board rotates in a direction in which it is closed, the oil damper comprises: a casing filled inside a hollow cylindrical chamber thereof with a viscous fluid, the casing being closed at one axial end portion thereof and open at the other end portion thereof; a pivoting member, assembled so as to be rotatable relative to the casing and which, in a center thereof a shaft portion to be disposed inside the chamber so as to be rotatable about an axis of the casing; a movable valve which is engaged, with play in the direction of rotation, with a projecting portion provided in an axially extending manner along a peripheral surface of the shaft, one side or the other side of which contacts the projecting portion, depending on the direction of rotation of the casing; fluid passages in one side and the other side, as well as in a contact portion of the projecting portion of the movable valve, such that the viscous fluid passes through the movable valve with different resistances, depending on the direction of rotation of the casing; and sealing means between the casing and the pivoting member so as to seal the viscous fluid; the fluid passages are arranged by fixing the casing to the fall board and engaging the pivoting member with a bearing member in the musical instrument main body such that a high resistance occurs to the passing fluid when the fall board is rotated in the direction to close it and a low resistance occur when the fall board is rotated in the direction to open it.
According to the above-mentioned arrangement, the present invention has the effects that the cost becomes low because the musical instrument main body can be used in common with the musical instrument main body provided with a fall board u
REFERENCES:
patent: 4641565 (1987-02-01), Tachida et al.
patent: 5056396 (1991-10-01), Furukawa
patent: 5067625 (1991-11-01), Numata
Kabushiki Kaisha Kawai Gakki Seisakusho
Spyrou Cassandra C.
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