Music – Instruments – Wind
Reexamination Certificate
2000-03-21
2001-07-03
Hsieh, Shih-Yung (Department: 2837)
Music
Instruments
Wind
C084S389000, C084S390000, C084S395000, C084S396000
Reexamination Certificate
active
06255571
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a brass instrument and, more particularly, to a trombone and a valve used therein.
DESCRIPTION OF THE RELATED ART
A trombone is broken down into a mouthpiece, a main tube and a bell. The main tube contains a slide tube. The player puts the trombone on his left shoulder, and brows through the mouthpiece. The column of air vibrates so as to generate tones. The player slides the slide tube. Then, the trombone varies the effective length of the slide tube and, accordingly, the column of air, and changes the harmonic series.
A bypass tube is incorporated in a kind of trombone, and is connected to the slide tube by means of a valve. The bypass tube is branched from a portion of the slide tube, and returns to the slide tube at another portion. When the player manipulates the valve, the valve increases the effective length of the column of air, and changes the range of note.
FIG. 1
illustrates a typical example of the trombone. The prior art trombone comprises a mouthpiece (not shown), a main tube
1
, a bypass tube
2
and a bell
3
. The main tube includes an inner tube
4
and an outer tube
5
. The inner tube
4
is inserted into the outer tube
5
, and slidably supports the outer tube
5
. When most of the outer tube
5
is overlapped with the inner tube
4
, the column of air is relatively short. If a player projects the outer tube
5
from the inner tube
4
, the outer tube
5
prolongs the column of air, and the prior art trombone changes the harmonic series.
The bypass tube
2
is connected to the main tube
1
by means of a rotary valve
6
. The rotary valve
6
has four ports
7
,
8
,
9
and
10
. The ports
7
and
8
are connected to the main tube
1
, and the other ports
9
and
10
are connected to the bypass tube
2
. When the rotary valve
6
connects the port
7
to the port
8
, the ports
9
and
10
are disconnected from the ports
6
and
7
, and the column of air extends from the inner tube
4
through the rotary valve
6
to the bell
3
. The bypass tube
2
does not form any part of the column of air. If the player manipulates the rotary valve
6
, the rotary valve
6
connects the ports
7
and
8
to the ports
9
and
10
, respectively, and the column of air extends through the bypass tube
2
. As a result, the column of air is prolonged.
The rotary valve
6
is disclosed in U.S. Pat. No. 4,095,504, and is shown in
FIGS. 2 and 3
in detail. The rotary valve
6
largely comprises a casing
11
and a rotor
12
. The four ports
7
/
8
/
9
/
10
are formed in the casing
11
, and a column-shaped inner space is defined in the casing. The ports
7
and
8
are directed at 90 degrees from the other ports
9
and
10
. The port
9
is directed at 180 degrees from the port
10
, and the port
7
is aligned with the port
8
.
The rotor
12
is accommodated in the casing
11
, and occupies the column-shaped inner space. The rotor
12
has a shaft
13
and a core
15
assembled together, and the shaft
13
has a short projection
13
a
and a long projection
13
b
. The center axes of these projections
13
a
/
13
b
are aligned with the axis of the core
15
, and the projections
13
/
14
are rotatably supported by the casing
11
. The long projection
13
b
extends through the casing
11
.
Recesses
16
/
17
are formed in the core
15
, and a cylindrical seal member
18
is inserted between the inner surface of the casing
11
and the core
15
. The cylindrical seal member
18
does not permit the air to flow through the gap between the inner surface of the casing
11
and the core
15
. For this reason, the air is allowed to flow only through the recesses
16
/
17
inside the casing
11
. The recesses
16
/
17
are generally sectoral in cross section as shown in
FIG. 2
, and the bottom surfaces are gently curved. The recesses
16
/
17
are positioned in such a manner as to be aligned with the ports
7
to
10
.
The core
15
is fixed to the shaft
13
by means of bolts
19
, and a lever (not shown) is connected to the long projection
13
b
. When a player pushes the lever, the rotor
12
, i.e., the shaft
13
and the core
15
turn in the column-shaped inner space together, and the core
15
changes the location of the recesses
16
/
17
. When the rotor
12
is in the position shown in
FIG. 2
, the ports
7
and
8
are connected through the recesses
16
/
17
to the other ports
9
and
10
, respectively, and the bypass tube
2
prolongs the column of air. On the other hand, if the rotor
12
turns at 90 degrees, the ports
7
and
9
are connected through the recesses
16
and
17
to the other ports
8
and
10
, respectively, and the bypass tube
2
is disconnected from the main tube
1
.
A problem is encountered in the trombone equipped with the prior art rotary valve shown in
FIGS. 2 and 3
in that the player feels the tone color and the intervals unstable when the bypass tube
2
prolongs the column of air. The player further feels the breath heavy. This is because of the fact that the prior art rotary valve increases the resistance against the air-flow and an abrupt change in the acoustic impedance.
As described hereinbefore, the bypass tube
2
prolongs the column of air, and the tones are produced from the vibrations of the air column. When the player blows the mouthpiece, the breath causes the air to flow through the main tube
1
. If the prior art rotary valve connects the bypass tube
2
to the main tube
1
, the prior art rotary valve guides the air-flow from the main tube
1
to the bypass tube
2
and from the bypass tube
2
toward the bell
3
. The ports
9
and
10
are directed at 90 degrees with respect to the other ports
7
/
8
, and, accordingly, the air-flow is bent at 90 degrees twice. Thus, the prior art rotary valve increases the resistance against the air-flow. Although the main tube
1
and the bypass tube
2
are circular in cross section, the cross sections of the recesses
16
/
17
are widely deformed from the circular cross section (see FIG.
3
). This results in the abrupt change of the acoustic impedance at the boundary between the main/bypass tubes
1
/
2
and the recesses
16
/
17
. Thus, the problem is reasoned from the large resistance and the abrupt change of the acoustic impedance.
Another prior art rotary valve is disclosed in Japanese Patent Publication of Unexamined Application (laid-open) No.
62-67590
. Japanese Patent Publication of Unexamined Application No.
62-67590
is corresponding to the specification for German Patent Application No. P3533400.2 filed on Sep. 19, 1985. The prior art rotary valve is used in a trumpet or a horn. An application to a trombone is not suggested in the Japanese Patent Publication of Unexamined Application.
The prior art rotary valve is shown in
FIG. 4
, and comprises a casing
21
, a bearing unit
22
, two valve bodies
23
/
24
and a connecting tube
25
. The casing
21
is separated into two parts
26
/
27
, and the two parts
26
/
27
are provided on both sides of the bearing unit
22
. The part
26
has three ports
28
/
29
/
30
, and the port
28
is directed at 90 degrees with respect to the other port
29
. Similarly, the part
27
has three ports
31
/
32
/
33
, and the port
31
is directed at 90 degrees with respect to the other port
32
. The port
30
is connected through the connecting tube
25
to the port
33
. The ports
28
/
31
are connected to two parts of a main tube (not shown), and a bypass tube (not shown) is connected at both ends to the ports
29
/
32
.
The valve bodies
23
/
24
is shaped in a frustum of cone, and are respectively accommodated in the parts
26
/
27
, respectively. The valve bodies are connected to each other, and are rotatably supported by the bearing unit
22
. Air passages are formed in the valve bodies
23
/
24
, and selectively connect the ports
28
/
31
to the ports
30
/
33
and the ports
29
/
32
depending upon the position in the casing
21
.
When a player rotates the valve bodies
23
/
24
, the prior art rotary valve connects the bypass tube to the main tube, or disconnects the
Hsieh Shih-yung
Ostrolenk Faber Gerb & Soffen, LLP
Yamaha Corporation
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