Music – Instruments – Rigid vibrators
Reexamination Certificate
1999-12-15
2001-06-12
Hsieh, Shih-Yung (Department: 2837)
Music
Instruments
Rigid vibrators
C084S403000
Reexamination Certificate
active
06245978
ABSTRACT:
FIELD OF THE INVENTION
The field of the invention is keyboard musical percussion instruments and acoustics.
BACKGROUND OF THE INVENTION
A category of musical instruments known as “keyboard percussion instruments” includes marimbas, vibraphones, xylophones and glockenspiels. The “keys” on a keyboard percussion instrument are known as “tone bars.” A basic feature of a keyboard musical percussion instrument is a suspension system that holds the tone bars in place, while allowing them to ring freely. Various types of suspension systems have been developed.
In the earliest xylophones, the tone bars were suspended on strips of straw. For this reason, they were sometimes called a “stroefiddle” or “straw fiddle.” Beginning in the early part of this century, the tone bars of keyboard musical percussion instruments were similarly suspended on strips of wool felt. In many cases, the bars of these early instruments were not drilled. Instead, they were held in place on a frame by crisscrossed straps or string. Although such straw or felt suspension systems are no longer used on marimbas, xylophones and vibraphones, in some glockenspiels with steel tone bars, felt strips are still used under the tone bars.
The earliest wooden keyboard percussion instruments manufactured in North America, i.e., the xylophone and the marimba, used a suspension system developed in Central America during the 19th century. This system employed horizontal holes drilled entirely through the width of the tone bar at the two average nodal points of the bar. (A nodal point, or non-vibrating point, on a percussive tone bar is typically located approximately one quarter bar length from each end of the bar.) After all of the tone bars are drilled for an entire keyboard, i.e., two holes per bar, a string or cord was passed through the holes. The entire keyboard was then suspended on a series of “stand-offs” or “bar posts” located between each tone bar. This drill-and-string suspension system is still used on professional-quality marimbas and xylophones.
In the drill-and-string system, twice the width of the tone bar is in contact with the suspension cords. Thus, in the case of a low-range marimba bar 3.5 inches wide, 7 inches of tone bar are in contact with the suspension cord. This extensive contact produces a tone-dampening effect. In addition, the density, grain, elasticity and growth patterns of wood inevitably vary, and the non-uniform properties of a wooden tone bar can produce non-uniform, unpredictable nodal paths. Any undesirable dampening resulting from contact with the suspension cord becomes more pronounced in wooden bars, because the cord is frequently in contact with live, i.e., vibrating, regions of the bar. Other disadvantages of a drill-and-string suspension system include cord breakage, audible vibration of the cord against the tone bar, and the considerable manufacturing expense associated with drilling two holes in each of as many as sixty-one bars (on a five-octave marimba) made of steel or very hard wood.
More recently, in many commercial musical keyboard percussion instruments, the tone bars are attached upon each of the pair of rails by a screw engaged loosely through a hole extending from the top surface, through the tone bar, into the respective support rail therebelow, the screws being located at each of the two nodes of the fundamental mode of vibration, i.e., at “Node A” and “Node B” of tone bar.
In a prior art commercially available glockenspiel, each tone bar is supported at four points by a pair of bumpers resting on each of a pair of support rails, with the tone bar secured by a pin extending from one rail into a vertical through hole in the tone bar. The pairs of bumpers and the pin are located at each of the two nodes of the fundamental mode of vibration, i.e., at “Node A” and “Node B” of tone bar.
SUMMARY OF THE INVENTION
According to one aspect of the invention, in a tone bar suspension assembly for mounting a tone bar of a keyboard musical percussion instrument having a series of tone bars supported by at least one pair of spaced-apart support rails, each tone bar having a tone bar body with first and second nodes of its fundamental mode of vibration (Node A and Node B) spaced from each other along a longitudinal axis of the tone bar body, and the tone bar body defining a bottom surface and a mounting hole formed in the bottom surface at Node A of the tone bar body, the tone bar suspension assembly comprises first and second suspension bumpers extending from a first support rail of the pair of support rails and having upper suspension surfaces to engage the bottom surface of the tone bar body at spaced apart locations in a plane generally transverse to the longitudinal axis of the tone bar body at Node B, and a suspension pin extending from a second support rail of the pair of support rails to engage in the mounting hole defined in the bottom surface of the tone bar body at Node A.
According to another aspect of the invention, a keyboard musical percussion instrument comprises at least a first pair of a first support rail and a second support rail, the first support rail being spaced from the second support rail; a series of tone bars, each tone bar comprising a tone bar body with first and second nodes of its fundamental mode of vibration (Node A and Node B) spaced from each other along a longitudinal axis of the tone bar body, and the tone bar body defining a bottom surface and a mounting hole formed in the bottom surface at Node A; and a tone bar suspension assembly for mounting the series of tone bars to the first and second, spaced-apart support rails, the tone bar suspension assembly comprising first and second suspension bumpers extending from the first support rail and having upper suspension surfaces to engage the bottom surface of the tone bar body at spaced apart locations in a plane generally transverse to the longitudinal axis of the tone bar body at Node B, and a suspension pin extending from the second support rail to engage in the mounting hole.
Preferred embodiments of this aspect of the invention may include one or more of the following additional features. The mounting hole is a blind hole. The keyboard musical percussion instrument further comprises a positioning pin extending from the first support rail between opposed side surfaces of adjacent tone bars. Preferably, the positioning pin further comprises an elastic cap mounted thereupon and disposed between the opposed side surfaces of the adjacent tone bars. The first support rail is pivotable relative to the second support rail for adjustment of angular relationship of the first support rail to the second support rail. The keyboard musical percussion instrument further comprises a second pair of a third support rail and a fourth support rail, the third support rail being spaced from the fourth support rail, and the first and second support rails supporting a first set of tone bars and the third and fourth support rails supporting a second set of tones bars. The second and third support rails are fixed upon the instrument, and the first and fourth support rails are pivotably mounted upon the instrument at a first end, the first support rail being pivotable relative to the second support rail, for adjustment of angular relationship of the first support rail to the second support rail, and the fourth support rail being pivotable relative to the third support rail, for adjustment of angular relationship of the fourth support rail to the third support rail. The keyboard musical percussion instrument further comprises means for adjustment of the angular relationship of the first support rail to the second support rail. Preferably, the angular relationship of the first support rail to the second support rail is between about 4° and about 10°. The keyboard musical percussion instrument further comprises means for adjustment of the angular relationship of the fourth support rail to the third support rail. Preferably, the angular relationship of the fourth support rail to the third support rail is between about 4° and a
Fish & Richardson P.C.
Hsieh Shih-yung
Stevens Leigh Howard
LandOfFree
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