JPH0744749B2 - Tubular acoustic transformer - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tubular acoustic transformer, and more particularly to a tubular acoustic transformer useful for attaching to a portable alarm buzzer or the like.

[Prior Art] FIG. 6 is a cross-sectional view of an exponential horn 51 which is an example of a conventional acoustic transformer.

In this exponential horn 51, as in the case where the number of secondary windings is increased from the number of primary windings in an electric transformer to boost the voltage, the sound output side is exponentially expanded from the opening cross-sectional area S1 on the sound inlet side. By increasing the cross-sectional area up to the cross-sectional area S2 of the opening, the high acoustic radiation efficiency is obtained.

As other conventional acoustic transformers, a conical horn, a step horn, a parabolic horn, etc. are known.

[Problems to be Solved by the Invention] Since all conventional acoustic transformers such as exponential horns have a shape that expands in diameter, there is a problem that they are not suitable for mounting on a portable alarm buzzer or the like. In addition, it is difficult to manufacture and expensive.

Therefore, an object of the present invention is to provide a tubular acoustic transformer that has a shape convenient for mounting on a portable alarm buzzer and the like, can be manufactured at low cost, and can obtain high acoustic radiation efficiency.

[Means for Solving the Problems] The tubular acoustic transformer of the present invention is an acoustic transformer used by being connected to a sounding body, and a voice input is made at one end of a hollow cylindrical body made of a hard material and not expanded. Side opening and an audio output side opening at the other end, and further, a cutout having a predetermined width in the vertical axis direction is formed in the body of the hollow cylindrical body. .

In the above structure, the hollow cylindrical body can be manufactured by molding hard plastic into a cylinder or a rectangular cylinder. Further, it can be manufactured by bending a metal plate made of a hard material into a cylinder or a square tube so that there is a gap of a predetermined width between both ends in the width direction.

[Operation] The inventor of the present invention has made earnest studies in view of the above-mentioned problems, and as a result of providing a voice input side opening at one end and a voice output side opening at the other end of a hollow cylindrical body that does not expand in diameter, The cross-sectional area of the voice input side opening = the cross-sectional area of the voice output side opening),
While high acoustic radiation efficiency cannot be obtained, by adopting a structure in which a cut having a predetermined width is provided in the vertical axis direction in the hollow cylindrical body (apparent cross-sectional area of the sound output side opening =
Since the cross-sectional area of the opening at the other end of the hollow tubular body + the area of the notch) becomes (the cross-sectional area of the sound input side opening <the cross-sectional area of the sound output side opening), it was tested that high acoustic radiation efficiency can be obtained. I found it.

That is, according to the present invention, an acoustic transformer having a shape that does not expand the diameter and that has high acoustic radiation efficiency can be obtained.

[Examples] The present invention will be described in more detail based on the examples shown in the drawings. The present invention is not limited to this.

FIG. 1 shows a cylindrical acoustic transformer (11) according to an embodiment of the present invention.
In the cylinder (1) made of a hard material such as metal or plastic, a notch (2) having a predetermined width is provided halfway in the longitudinal direction, and as shown in FIG. The sounding body (3) can be inserted into the opening at one end.

The sounding body (3) may be any one such as an electromagnetic buzzer or a piezoelectric buzzer, but a part of the case is inserted into the cylinder (1) and connected.

Therefore, the diameter of the inner surface of the cylinder (1) is made to match the diameter of the outer surface of the sounding body (3) so that no gap is created between the cylinder (1) and the sounding body (3).

The sounding part of the sounding body (3) is inserted toward the inner surface of the cylinder (1).

The length of the cylinder (1) and the shape, width, length, etc. of the notch (2) may be selected according to the frequency band of the sound generated by the sounding body (3) for which the acoustic emission efficiency is desired to be the highest. .

FIG. 3 shows a cylindrical acoustic transformer (21) according to another embodiment of the present invention.
FIG. 2 shows the cutout (2) in the tubular acoustic transformer 11 shown in FIG. 1 provided from one end to the other end of the cylinder (1).

FIG. 4 shows a cylindrical acoustic transformer (31) according to still another embodiment of the present invention, in which a rectangular tube (1 ') made of a hard material is provided with a notch (2) having a predetermined width on the vertical axis. The sounding body is provided halfway in the direction, and the sounding body is inserted into the opening at one end on the side where the cut (2) is not provided.

The length of each side of the rectangular tube (1 ') is equal to the sounding body (3) to be attached.
Match the length of each side of the square tube (1 ') and sound generator (3)
There should be no gap between them.

The length of the rectangular tube (1 ') and the shape, width, length, etc. of the notch (2) should be selected according to the frequency band of the sound generated by the sounding body (3) for which the acoustic emission efficiency is to be maximized. Good.

FIG. 5 shows a cylindrical acoustic transformer (41) according to still another embodiment of the present invention, in which a rectangular tube (1 ') made of a hard material is vertically provided with a notch (2) having a predetermined width. It is provided from one end to the other end in the axial direction. The sounding body (3) is inserted into the opening on the one end side.

The cylinder (1) and the rectangular tube (1 ') may be manufactured by processing metal, plastic, or the like, and a plate of metal, plastic, or the like may be formed with a gap having a predetermined width between both ends in the width direction. You may make it by holding it and bending it.

According to the cylindrical acoustic transformers (11) to (41), it is impossible to obtain high acoustic radiation efficiency over a wide frequency range like an acoustic transformer having an expanded diameter such as an exponential horn. In a limited frequency range such as a buzzer, a sufficiently high acoustic radiation efficiency can be obtained.

EFFECTS OF THE INVENTION The tubular acoustic transformer of the present invention has a shape that does not expand the diameter,
It is also possible to have a structure in which the length is expanded and contracted by sliding it on the outer surface of the sounding body, which is suitable for attaching to a portable buzzer or the like. Further, it is easy to manufacture and can be manufactured at low cost. Furthermore, a sufficiently high acoustic radiation efficiency can be obtained in the required frequency band.

[Brief description of drawings]

1 (a) is a left side view of an embodiment of the tubular acoustic transformer of the present invention, FIG. 1 (b) is the same front view, FIG. 1 (c) is the same right side view, and FIG. 1 is a perspective view of the usage mode of the tubular acoustic transformer of FIG. 1, FIG. 3 (a) is a left side view of another embodiment of the tubular acoustic transformer of the present invention, and FIG. 3 (b) is the same. Front view, third
FIG. 4 (c) is a right side view, FIG. 4 (a) is a left side view of still another embodiment of the tubular acoustic transformer of the present invention, and FIG. 4 (b) is the same front view and FIG. FIG. 5 (c) is a right side view of the same, FIG. 5 (a) is a left side view of still another embodiment of the tubular acoustic transformer of the present invention, and FIG. 5 (b) is a front view of the same. FIG. 6C is a right side view of the same, and FIG. 6 is a sectional view of an example of a conventional acoustic transformer. (Description of symbols) (1) …… Cylinder (1 ′) …… Square tube (2) …… Notch (3) …… Sound generator (11) to (41) …… Sound transformer.

Claims (1)

[Claims] 1. An acoustic transformer used in connection with a sounding body, wherein a hollow cylindrical body made of a hard material and having no diameter expansion is provided with an opening on one side for voice input and another end on the other side for voice output. A tubular acoustic transformer, characterized in that an opening is provided, and further, a cutout having a predetermined width in a longitudinal direction is provided in a body of the hollow tubular body.