JP4075244B2 - Speaker - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a loudspeaker, and more particularly to a loudspeaker having an acoustic amplifier that complements a frequency range that is insufficient for sound emitted by a vibrator.
[0002]
[Prior art]
In a conventional speaker, examples of the acoustic amplifier include a megaphone, a front load horn, and a back load horn. As a shape of the horn, for example, there is a straight horn as shown in FIG. 4, but there are an exponential horn, a high public horn, and the like. A vibrator is arranged in such a throat portion 2 of the horn 1, and the acoustic energy radiated by the vibration of the vibrator is concentrated on the shaft of the horn 1, thereby increasing the sound pressure.
[0003]
[Problems to be solved by the invention]
However, in a speaker using such a horn, it is difficult to design and manufacture the shape of the horn. Further, the change in external pressure is concentrated on the throat portion of the horn, and the vibrator disposed in this portion is easily damaged.
[0004]
Therefore, a main object of the present invention is to provide a speaker that is easy to design and has a sufficient acoustic amplification effect.
[0005]
[Means for Solving the Problems]
The present invention is a speaker including a vibrator, a diaphragm that is vibrated by the vibrator, and a resonance cylinder disposed on the diaphragm, and a plurality of different air column resonance frequencies with the vibrator at the center. This is a speaker in which resonance cylinders are arranged concentrically.
Such a loudspeaker can have a structure in which a resonance cylinder having a high air column resonance frequency is disposed near the vibrator, and a resonance cylinder having a low air column resonance frequency is disposed away from the vibrator.
[0006]
The air column resonance frequency of the resonance cylinder is determined by the length of the cylinder and the speed of sound. Therefore, by changing the lengths of the plurality of resonance cylinders, it is possible to obtain characteristics combining a plurality of air column resonance frequencies.
In order to obtain such characteristics, a resonance cylinder having a high air column resonance frequency is disposed near the vibrator, that is, a short resonance cylinder is disposed, and a resonance cylinder having a low air column resonance frequency is disposed far from the vibrator. That is, a long resonance cylinder is arranged.
[0007]
The above object, other objects, features, and advantages of the present invention will become more apparent from the following detailed description of embodiments of the present invention with reference to the drawings.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a perspective view showing an example of the speaker of the present invention, and FIG. 2 is a sectional view thereof. The speaker 10 includes a diaphragm 12. A vibrator 14 is attached to the center of the diaphragm 12. The vibrator 14 includes a hemispherical vibrating body 16 formed of a piezoelectric body, and electrodes 18 and 20 are formed on both surfaces thereof. The vibrating body 16 is polarized from the electrode 18 side toward the electrode 20 side. Of course, the vibrating body 16 may be polarized from the electrode 20 side toward the electrode 18 side.
[0009]
A plurality of resonance cylinders 22, 24, 26, and 28 are mounted on the diaphragm 12. These resonance cylinders 22 to 28 are formed to have different diameters. The resonance cylinders 22 to 28 are arranged so as to be concentric with the vibrator 14 as the center. The resonance cylinders 22 to 28 are formed to have different lengths. A short resonance cylinder 22 is disposed near the vibrator 14, and gradually longer resonance cylinders 24, 26, and 28 are disposed as the distance from the vibrator 14 increases.
[0010]
In the speaker 10, by applying a signal to the electrodes 18 and 20 of the vibrator 14, the hemispherical vibrating body 16 vibrates so as to expand or contract as a whole. Due to such vibration, sound is radiated from the surface of the vibrator 12, and the diaphragm 16 vibrates accordingly. At this time, the resonance cylinders 22, 24, 26, and 28 resonate at their respective air column resonance frequencies.
[0011]
The air column resonance frequency f of the one-end open cylinder is obtained by f = C / 4L. Here, C is the speed of sound and L is the length of the cylinder. Therefore, the air column resonance frequency is high when the length of the cylinder is short, and the air column resonance frequency is low when the length of the cylinder is long. That is, in the speaker 10 shown in FIG. 1, the air column resonance frequency of the inner resonance cylinder 22 is the highest, and the air column resonance frequency of the outer resonance cylinder 28 is the lowest.
[0012]
The sound pressure characteristics of the speaker 10 are shown in FIG. As can be seen from FIG. 3, in the case of only the hemispherical vibrator 14, the sound pressure at a certain frequency is high and has a characteristic like one mountain. However, a peak is formed at a frequency slightly lower than the peak of the sound pressure due to the vibrator 14 by the resonance cylinder 22 having the innermost length L1. Similarly, a peak is formed at a low frequency by the resonance cylinders 24, 26, and 28 having lengths L2, L3, and L4. Therefore, the speaker 10 as a whole can obtain a substantially flat sound pressure characteristic obtained by synthesizing the peaks.
[0013]
Thus, the speaker 10 can obtain a substantially flat sound pressure characteristic in a wide frequency range. In addition, it is not necessary to form a horn having a complicated shape in order to perform acoustic amplification, and it is only necessary to adjust the length of the cylinder, and design and manufacture are easy. In such a structure, the influence of the external pressure applied to the vibrator 14 is small, and the vibrator 14 is not easily damaged.
[0014]
The vibrator 14 is not limited to a hemispherical piezoelectric vibrator, and other kinds of vibrators such as a vibrator that vibrates a diaphragm using a voice coil and a magnet can be used.
[0015]
【The invention's effect】
According to the present invention, a substantially flat sound pressure characteristic can be obtained in a wide frequency range, and a speaker that is easy to design and manufacture can be obtained.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an example of a speaker of the present invention.
FIG. 2 is a cross-sectional view of the speaker shown in FIG.
FIG. 3 is a graph showing the sound pressure characteristics of the speaker shown in FIG.
FIG. 4 is an illustrative view showing one example of a horn used in a conventional speaker.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Speaker 12 Diaphragm 14 Vibrator 16 Vibrating body 18,20 Electrode 22,24,26,28 Resonance cylinder

Claims (2)

Vibrator,
A speaker including a diaphragm that is vibrated by the vibrator, and a resonance cylinder disposed on the diaphragm,
A speaker in which a plurality of resonance cylinders having different air column resonance frequencies around the vibrator are arranged concentrically. The speaker according to claim 1, wherein the resonance cylinder having a high air column resonance frequency is disposed in a portion close to the vibrator, and the resonance cylinder having a low air column resonance frequency is disposed as the distance from the vibrator increases.

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