JPH0247678Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an electroacoustic transducer used as a buzzer or the like.

FIG. 1 shows a conventional piezoelectric electroacoustic transducer, in which a sound emitting hole is provided at the center of a closing wall 2 that closes off one end of a cylinder 1, and a plate is provided on the inner peripheral surface of the cylinder 1. A shaped piezoelectric vibrator 4 is attached in a confidential manner, and the space between the piezoelectric vibrator 4 and the sound emitting hole 3 is used as a resonance chamber 5, and a circuit board 6 is attached to the other end of the cylindrical body 1. Note that the piezoelectric vibrator 4 is mounted on the circuit board 6.
Circuit components 7 constituting a self-excited oscillation circuit for driving are attached.

Therefore, when the piezoelectric vibrator 4 is driven by a self-excited oscillation circuit, the piezoelectric vibrator 4 vibrates, and a sound of a constant frequency is emitted from the sound emitting hole 3. by the way,
When the drive voltage when driving this piezoelectric vibrator 4 by separately excited oscillation is e ₀ and the output sound pressure from the sound emission hole 3 is P, the sensitivity P/e ₀ is shown in FIG. 2 according to the frequency. It changes like that. Also, when the feedback voltage from the piezoelectric vibrator 4 is e ₁ , the drive voltage e ₀ and the feedback voltage
The ratio e ₁ /e ₀ with e 1 changes as shown in Figure 3 depending on the frequency, and _the ratio is maximum at frequency 1 where the sensitivity P / e ₀ in Figure 2 is maximum, and the drive by the self-excited oscillation circuit Now let's sound at this frequency 1.

The frequency characteristics shown in FIGS. 2 and 3 vary depending on the volume of the resonance chamber 5 or the opening area of the sound emission hole 3, but in the case of the conventional electroacoustic transducer shown in FIG. Resonance chamber 5 so that ₀ is the maximum
The volume of the sound emitting hole 3 and the opening area of the sound emitting hole 3 were determined to be constant.

However, in such a conventional configuration,
Since the volume of the resonance chamber 5 and the opening area of the sound emission hole 3 are always constant, the required frequency and sensitivity may not be obtained due to variations in the dimensions of each part during production, or the sound emitted from the sound emission hole 3 may not be obtained. Even if you need to change the tone of the sound, you can change the frequency and
The drawback was that the tone could not be changed.

The present invention was developed with these circumstances in mind, and its purpose is to make it possible to vary the volume of the resonance chamber and the opening area of the sound emitting hole, thereby changing the timbre of the sound emitted from the sound emitting hole. The object of the present invention is to provide an electroacoustic transducer that can be changed as appropriate.

Hereinafter, the configuration of the present invention will be explained based on an embodiment shown in FIGS. 4 and 5.

In the figure, reference numeral 11 denotes a cylindrical body having a cylindrical shape with a bottom, and the closing wall 12 of this cylindrical body 11 has a large number of sound emitting holes 13A, 13B, ... 13F on the same circumference as shown in Fig. 5. The holes are arranged in the following order. These sound emitting holes 13A, 13B, . Further, the sound emitting holes 13A,
The same number of recesses 14, . . . as 13B, . . . 13F are provided at equal intervals in the circumferential direction. Furthermore, the cylindrical body 1
A threaded portion 15 is provided on the inner periphery of the open end of the opening.

In the figure, reference numeral 16 denotes a cylindrical resonance chamber adjustment body, and a threaded portion 17 is provided on the outer periphery of one end of this adjustment body 16 to be screwed into the threaded portion 15, and a piezoelectric vibrator 18 is provided at the opening on one end, and a piezoelectric vibrator 18 is provided at the other end. The side opening is formed by the circuit board 19.
Each is closed, and a circuit component 20 for configuring a self-excited oscillation circuit is mounted on the circuit board 19. The piezoelectric vibrator 18 is connected to the resonance chamber adjustment body 16
A piezoelectric ceramic 22 with electrodes formed on both sides is adhered to one surface (the surface facing the circuit board 19) of a metal plate 21 that closes the opening of the metal plate 21. A return electrode is provided on the electrode on the opposite side. The space between the closing wall 12 and the metal plate 21 within the cylindrical body 11 is defined as a resonance chamber 23. However, the cylindrical body 11
The resonance chamber 23 is
The volume of will change steplessly.

In the figure, 24 is a sound emitting hole adjustment body, which is the cylindrical body 1.
It fits into the closing wall 12 side of No. 1 from the outside. This sound emitting hole adjustment body 24 has the largest sound emitting hole 13 provided in the cylindrical body 11 at a portion in contact with the closing wall 12.
It has a communication hole 25 with a slightly larger diameter than A, and
The cylindrical body 11 has engaging protrusions 26, 26 at two locations in contact with the outer circumferential surface thereof, and both protrusions 26, 26 are selectively inserted into any two of the recesses 14 provided in the cylindrical body 11. It is designed so that it can be fitted. When any two of the protrusions 26, 26 are fitted into the recesses 14, the center of the communication hole 25 is aligned with the sound emitting hole 13A, 13B,...13.
The sound emitting hole coincides with the center of any one of the holes F, and the other sound emitting holes are closed by the sound emitting hole adjuster 24. Therefore, by rotating the sound emitting hole adjustment body 24 with respect to the cylindrical body 11 and fitting both protrusions 26, 26 into other recesses 14, 14, another sound emitting hole is overlapped with the communication hole 25. be able to.

With the above configuration, the piezoelectric vibrator 18
By driving the piezoelectric vibrator 18 with a self-excited oscillation circuit to vibrate the piezoelectric vibrator 18, a sound emitting hole (one of 13A, 13B,...13F) overlapping the communication hole 25 is created.
It can generate more sound. Moreover, when the resonance chamber adjustment body 16 is rotated with respect to the cylinder main body 11,
The volume of the resonance chamber 23 changes steplessly. For example, in separately excited oscillation, when the volume of the resonance chamber 23 changes, the frequency 1 at which the sensitivity P/e ₀ or the ratio e ₁ /e ₀ becomes maximum changes as shown in FIG.
Therefore, even if there are variations in the dimensions of each part during production, the resonance chamber adjuster 16 can be rotated to adjust the resonance chamber 2.
By steplessly varying the volume of 3, it is possible to easily generate sound at a desired frequency. Furthermore, the timbre of the sound emitted from the sound emitting hole can be changed.

In addition, FIG. 6 shows the change characteristics of frequency 1 when the opening area of the sound emission hole is varied by rotating the sound emission hole adjustment body 24, and the characteristics of the resonance chamber adjustment body 16 and the sound emission hole adjustment body 24, respectively. The change characteristics of frequency 1 when both the volume of the resonance chamber 23 and the opening area of the sound emission hole are varied by rotation are shown.

It should be noted that the present invention is not limited to the embodiments described above, and can be implemented with various modifications. For example, as shown in FIG. 7, a plurality of annular grooves 27 are provided on the outer peripheral surface of the resonance chamber adjustment body 16, and a plurality of annular grooves 27 are provided on the inner peripheral surface of the cylindrical body 11. A configuration may also be adopted in which an engaging protrusion 28 is provided to extend and contract the cylindrical body 11 and the resonance chamber adjuster 16 linearly to change the volume of the resonance chamber.

In addition, a sound emission hole 13 provided in the cylindrical body 11
A, 13B, . . . 13F can have any shape. Furthermore, although the above embodiments have been described as piezoelectric electroacoustic transducers, the present invention is not limited to piezoelectric transducers, but can also be applied to electromagnetic, electrodynamic, and other electroacoustic transducers.

As detailed above, the present invention comprises a cylinder body and a resonance chamber adjustment body, and these cylinder bodies and the resonance chamber adjustment body are connected by a coupling structure, and this connection structure allows the cylinder body to be connected to the resonance chamber adjustment body. A volume variable structure that changes the volume of the resonance chamber by relatively moving the body body and a resonance chamber adjustment body, and a plurality of sound emitting holes each having a different opening area are arranged at one end of the cylindrical body body. Further, a sound emitting hole adjustment body is provided having a communication hole that selectively opens each of the sound emitting holes one by one by sliding on the sound emitting hole arrangement surface of the cylindrical body, and the cylindrical body A fitting portion consisting of a protrusion and a recess that removably fit into each other is provided on opposing surfaces of the main body and the sound emission hole adjustment body, and this fitting portion allows the sliding position of the sound emission hole adjustment body to be adjusted to the above-mentioned position. and a sound emission hole adjustment mechanism that stops each sound emission hole at the position where each sound emission hole is opened individually, and the volume of the resonance chamber and the opening area of the sound emission hole are controlled by the volume variable structure and the sound emission hole adjustment mechanism. It is made to be variable.

Therefore, according to the present invention, even if there are variations in the dimensions of each part during manufacturing, or even if it is necessary to change the tone after manufacturing, the sound emitted from the sound emitting hole can be easily and accurately set to the desired tone. can do.

In addition, since the present invention is equipped with both a volume variable structure and a sound emission hole adjustment mechanism, the frequency can be varied by the cooperation between the volume change and the sound emission hole opening area, as shown in Figure 6. be done. For this reason, it is possible to cover a wide frequency range without increasing the thickness of the buzzer or lowering the volume more than necessary.This makes it possible to obtain sufficient volume in a small size and to achieve the desired tone. can be generated.

By the way, when only a structure that changes volume is provided, the frequency is changed only by changing the volume, so if you try to cover a wide frequency band, you have to set the screw stroke large. If this is done, the thickness of the electroacoustic transducer increases, leading to an increase in size. Further, when only a structure for varying the opening area of the sound emitting hole is provided, the frequency variable range is generally narrow, and it may not be possible to generate a desired frequency (timbre) with only this structure. Furthermore, since the volume generally decreases as the opening area decreases, it becomes difficult to obtain the desired volume.

Furthermore, the present invention has a mechanism for varying the opening area of the sound emission hole, as described above, in which a plurality of sound emission holes with different opening areas are provided in advance, and these sound emission holes are selectively opened. Moreover, the selected position of the sound emitting hole is fixed by a fitting structure consisting of a protrusion and a recess so that it does not change easily.

Therefore, when adjusting the frequency, for example, first the sound emitting hole that produces a tone close to the desired tone is selectively opened from among the plurality of sound emitting holes, and in this state, the volume is finely adjusted using the variable volume structure. By making adjustments, it is possible to generate a desired tone frequency. That is, it is possible to perform rough adjustment of the frequency by selecting the sound emitting holes, and fine adjustment by varying the volume. Moreover, since it has a fitting structure, the selected position of the sound emitting hole is difficult to change easily, so that, for example, when changing the volume after selecting the sound emitting hole, the selected position of the sound emitting hole cannot be easily changed. This can prevent changes regardless of the operator's intention. Therefore, it becomes possible to efficiently and accurately adjust the frequency.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of the configuration of a conventional electroacoustic transducer, FIGS. 2 and 3 are views showing an example of frequency characteristics, and FIG. 4 is an electroacoustic transducer according to an embodiment of the present invention. 5 is a plan view of the transducer, FIG. 6 is a diagram showing changes in frequency characteristics, and FIG. 7 is a partial diagram of an electroacoustic transducer in another embodiment of the present invention. FIG. 3 is a cutaway side view. 11... Cylinder main body, 13A to 13F... Sound emission hole, 15... Threaded portion, 16... Resonance chamber adjustment body, 1
7...Screw part, 18...Piezoelectric vibrator, 19...Circuit board, 20...Circuit component, 23...Resonance chamber, 2
4... Sound emission hole adjustment body, 25... Communication hole.

Claims (1)

[Claims for Utility Model Registration] A plate-shaped vibrator is disposed inside a cylindrical body, an internal space surrounded by the cylindrical body and the vibrator is used as a resonance chamber, and the cylindrical body facing the vibrator is In an electroacoustic transducer, a sound emitting hole is provided at one end to communicate a resonance chamber with the outside, and the vibrator is driven by a self-excited oscillation circuit to generate sound from the sound emitting hole, the cylindrical body being a cylindrical body. Consisting of a main body and a resonance chamber adjustment body, the cylinder main body and the resonance chamber adjustment body are coupled by a coupling structure, and the coupling structure allows the cylinder body and the resonance chamber regulation body to be relatively moved. a volume variable structure for varying the volume of the resonance chamber; a plurality of sound emitting holes each having a different opening area at one end of the cylindrical body; A sound emitting hole adjusting body having a communication hole that selectively opens each of the sound emitting holes one by one by sliding the body is provided, and a sound emitting hole adjusting body is provided on opposing surfaces of the cylindrical body and the sound emitting hole adjusting body. A fitting portion consisting of a protrusion and a recess that is removably fitted to the holder is provided, and the fitting portion stops the sliding position of the sound emitting hole adjustment body at a position where each of the sound emitting holes is individually opened. 1. An electroacoustic transducer comprising: a sound emitting hole adjustment mechanism configured to adjust the sound emitting hole;