JP2004350001A - Speaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a speaker capable of faithfully reproducing an input signal. <P>SOLUTION: In the speaker, a horn 30 communicates with a speaker chamber 20. The horn 30 is allowed to communicate with the speaker chamber 20 via a slit 40. The slit 40 is formed in a shape that has an opening area smaller than an inlet 31 of the horn 30, and constricted to the inlet 31. The speaker chamber 20 is formed in a longitudinal shape and the communication of the horn 30 is made at the upper end of the speaker chamber 20. As a result, horns having two kinds of lengths (a first horn having length L and a second one having length L+Lsp) are substantially formed, and a valley on frequency characteristics in a radiation sound of the entire speaker is buried by a radiation sound of the second horn. The ratio d/D of width the (d) of the slit 40 and the inlet 31 of the horn 30 is preferably set to 0.09-0.2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a loudspeaker, and more particularly to a loudspeaker having a horn communicating with a speaker room.
[0002]
[Prior art]
In general, a speaker is composed of a speaker unit that is a mechanism part that emits sound, a box that houses the speaker unit, that is, an enclosure, and a circuit called a dividing network.
[0003]
Conventionally, as a speaker for audio, a multi-way speaker including three types of speaker units for low-pitched sound (woofer), medium-tone (squawker), and high-pitched sound (tweeter) has been widely used. This is because one speaker unit could not generate sound uniformly in a wide frequency band.
[0004]
On the other hand, a multi-way speaker composed of three types of speaker units generally requires a large installation area. Therefore, when only a limited space is secured, a full-range speaker that can be constituted by one speaker unit is used. ing.
[0005]
As a full-range speaker, for example, there is a backloaded horn speaker (see Non-Patent Document 1). The backloaded horn type speaker 700 shown in FIG. 7 includes a speaker room 720 in which a speaker unit 710 is mounted, and a horn 730 for guiding sound waves in the speaker room 720 to the front. The sound directly radiated from the speaker unit 710 does not generate a sound wave in a low sound range of 200 Hz or less even if the diaphragm (cone) is actually vibrating. The reason is that the air in front of the diaphragm causes a lateral flow, and the lower the frequency, the greater the degree. Therefore, in order to compensate for the direct radiated sound from the speaker unit 710, the bass sound is emphasized and radiated from the opening 733 of the horn 730. In particular, sounds near the fundamental frequency (f ₀ = c / 2L) are emphasized. Here, c is the speed of sound, and L is the length of the horn 730. For example, if the basic frequency is to be set to 70 to 80 Hz, the length L of the horn 730 needs to be about 2 m.
[0006]
[Non-patent document 1]
"Speaker System" (pages 288-297), edited by Takeo Yamamoto, published by Radio Engineering Company (1977)
[0007]
[Problems to be solved by the invention]
The original purpose of a loudspeaker is to radiate into the air acoustic power with an acoustic waveform essentially equivalent to the electrical input waveform. In other words, this can be said to be "reproduction of an input signal".
[0008]
However, the above-described multi-way speaker requires an LCR circuit as a dividing network, and such an LCR circuit not only loses energy but also deteriorates phase characteristics of radiated sound. Furthermore, a large installation area is required, and it is difficult to install in a limited space.
[0009]
On the other hand, in the backloaded horn type speaker shown in FIG. 7, the frequency characteristics of the radiated sound deteriorate. FIG. 8 shows the frequency characteristics of this speaker. In FIG. 8, the direct sound 200 emitted from the speaker unit 710 has a low sound pressure level (power) at a low frequency, so that the sound 211, 212, 213, 214 emitted from the opening 733 of the horn 730 reduces the low frequency range. As a supplement, the radiated sounds 211 to 214 from the opening 733 are such that peaks a1, a2, a3, and a4 and valleys between these peaks are arranged. Due to the radiated sounds 211 to 214 from the opening 733 and the direct radiated sound 200 from the speaker unit 710, the frequency characteristic of the radiated sound of the entire speaker is the largest near the fundamental frequency (f ₀ = c / 2L). While there are mountains, there will also be large valleys. The existence of such a valley in the frequency characteristic was a major drawback of the conventional backloaded horn type speaker.
[0010]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a speaker that can faithfully reproduce an input signal without impairing phase characteristics and frequency characteristics.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, a speaker room in which a speaker unit that converts an electric signal into air vibration is mounted, and an entrance portion of the speaker room is connected to the speaker room through a communication port. And a speaker provided with a horn based on a length (L + Lsp) obtained by adding a length Lsp of the speaker chamber to a length L of the horn. The horn has a smaller opening area than the entrance of the horn so as to fill a valley on the frequency characteristic of the entire radiated sound, and is characterized by comprising a slit narrowed with respect to the entrance.
[0012]
According to the present invention, the LCR circuit is unnecessary, so that the phase characteristics can be prevented from being impaired. Further, two types of horns (a first horn having a length L and a second horn having a length L + Lsp) are provided. A substantially formed valley on the frequency characteristic will be filled by the sound radiated by the second horn, and the frequency characteristic will be improved as compared to a conventional backloaded horn speaker. In addition, since only one speaker unit is required and two types of horns share a sound path, the size and weight can be reduced.
[0013]
According to a second aspect of the present invention, in the first aspect of the present invention, the speaker room has a height greater than a distance between a front plate to which the speaker unit is attached and a rear plate facing the front plate. In this case, the distance between the top plate and the bottom plate facing each other is long, and the back plate is configured to form the slit with either the top plate or the bottom plate.
[0014]
According to this configuration, since the speaker room has a vertically long shape and the slit is formed by using the back plate that partitions the speaker room and the horn, the speaker capable of faithfully reproducing the input signal can be provided deeply. Can be manufactured without increasing the size and space is saved.
[0015]
The ratio d / D of the width d of the slit to the width D of the inlet of the horn is preferably set to 0.09 to 0.2, as described in claim 3.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of a speaker according to the present invention will be described in detail with reference to the accompanying drawings.
[0017]
First, the principle of the present invention will be described with reference to FIGS.
[0018]
The speaker 100 shown in FIG. 1 includes a speaker unit 10 that converts an electric signal into air vibration to emit a sound, a hollow speaker room 20 to which the speaker unit 10 is attached, and an entrance 31 (generally “throat”) in the speaker room 20. ) Is provided with a hollow horn 30 communicating therewith. The horn 30 is formed such that the opening area gradually increases from the inlet 31 toward the opening 33, and the slit-shaped communication port 40 (hereinafter, referred to as “slit”) which is sharply narrowed with respect to the inlet 31. ) Communicates with the speaker room 20.
[0019]
When the speaker chamber 20 and the horn 30 are separated by the slit 40 as shown in FIG. 1, horns of substantially two kinds of lengths (referred to as “backloaded double horn”) are formed. One is from the slit 40 to the opening 33 (the so-called horn 30, also referred to as the "first horn"), and the other is the one in which the speaker room 20 is added thereto (the speaker room 20 and the horn 30). "2nd horn" 130).
[0020]
FIG. 2 shows the frequency characteristics of the speaker 100 in which the horns of two different lengths are formed as described above. In FIG. 2, a direct radiated sound 200 from the speaker unit 10, harmonics 211, 212, 213 and 214 radiated from the opening 33 based on the length L of the horn 30 (harmonics of the “first horn”), Based on the length (L + Lsp) obtained by adding the length Lsp of the speaker chamber 20 to the length L of the horn 30, overtones 221, 222, and 223 (overtones of the "second horn" 130) radiated from the opening 33. The frequency characteristics are shown separately.
[0021]
The intervals between the peak strings a1, a2, a3, and a4 (hereinafter, referred to as “first peak strings”) due to the harmonics of the “first horn” 30 are c / 2L. Further, the interval between the peak strings b1, b2, b3 (hereinafter, referred to as “second peak string”) due to the overtone of the newly formed “second horn” 130 is c / 2 (L + Lsp). The length Lsp of the speaker room 20 is appropriately determined, and the second peak b2 of the second peak row is positioned substantially at the center of the first peak a1 and the second peak a2 of the first peak row. For example, the frequency (c / (L + Lsp)) of the second peak b2 in the second peak row is 1.4 to 1.6 times the peak frequency (c / 2L) of the first peak a1 in the first peak row. To do so, the length Lsp of the speaker chamber 20 is made to be 1/4 to 3/7 times the length L of the horn 30.
[0022]
A speaker according to an embodiment to which the above principle is applied will be described. 3A is a cross-sectional view of the speaker 300, FIG. 3B is a cross-sectional view of a main part showing the periphery of the slit 40, and FIG.
[0023]
The speaker room 20 has a vertically long shape in which the distance between the upper surface plate 23 and the lower surface plate 24 that are vertically opposed to each other is longer than the distance between the front plate 21 to which the speaker unit 10 is attached and the rear plate 22 that faces the front plate 21. is there. For example, when the total length L of the bent horn 30 is 2 m, the length Lsp of the speaker chamber 20 is set to 50 cm to 86 cm.
[0024]
The rear plate 22 of the speaker room 20 has a role of partitioning the speaker room 20 and the entrance 31 of the horn 30 and a role of forming a slit 40 together with the upper surface plate 23. Specifically, the slit 40 is formed so as to be sandwiched between the upper end surface of the rear plate 22 of the speaker room 20 and the upper plate 23. In FIG. 3C, the right side plate 25 of the speaker room 20 is on the right side of the slit 40, and the left side plate 26 of the speaker room 20 is on the left side of the slit 40.
[0025]
In such a speaker 300, a “first horn” 30 having one end as the slit 40 and the other end as the opening 33, and a “second horn” having one end as the bottom plate 24 of the speaker room 20 and the other end as the opening 33. Are substantially formed.
[0026]
The ratio of the width d of the slit 40 to the width D of the inlet 31 of the horn 30 is d / D, and the magnitude of the peak row of the harmonics radiated from the “first horn” 30 and radiated from the “second horn”. It is possible to control the ratio of the overtone to the peak row size. FIG. 4 shows an example in which one side of the slit 40 is configured to be slidable by the movable plate 50. The movable plate 50 slides up and down (longitudinal direction of the back plate 22) along the back plate 22 of the speaker room. This sliding movement may be performed manually when the top plate 23 or the like is removed, or may be configured so that the amount of movement can be externally specified without removing the top plate 23 or the like.
[0027]
The length L of the horn 30 was 190 cm, the width D of the entrance 31 of the horn 30 was 34 mm, and the width d of the slit 40 was changed. The experimental data is shown in FIGS.
[0028]
5A shows a slit width d = 34 mm (d / D = 1.00), FIG. 5B shows a slit width d = 29 mm (d / D = 0.85), and FIG. 5C shows a slit width. d = 15 mm (d / D = 0.44), FIG. 6A shows a slit width d = 7 mm (d / D = 0.20), and FIG. 6B shows a slit width d = 3 mm (d / D = 0.09), and FIG. 6C shows the frequency characteristics of the sound radiated from the speaker when the slit width d is 1 mm (d / D = 0.03).
[0029]
In the case where d / D = 1.00 shown in FIG. 5A and the case where d / D = 0.85 shown in FIG. 5B, the difference in the sound pressure level between the peak A and the valley V is While exceeding 20 dB, the sound pressure level of the valley V becomes extremely lower than the sound pressure level of the surrounding frequency (70 Hz to 200 Hz). In the case where d / D = 0.20 shown in FIG. 6A and the case where d / D = 0.09 shown in FIG. 6B, the difference in the sound pressure level between the peak A and the valley V is As a result, the drop in the sound pressure level of the valley V is not so different from the sound pressure levels of other valleys (for example, valleys near 500 Hz). On the other hand, in the case of d / D = 0.03 shown in FIG. 6C, the slit width d was too small, so that the sound pressure level in the low frequency range (200 Hz or less) was lowered as a whole. (That is, the effect of the horn 30 for supplementing the bass is weakened.) According to the experimental data shown in FIGS. 5 and 6, the ratio d / D of the width d of the slit to the width D of the inlet of the horn is preferably set to 0.09 to 0.2.
[0030]
According to the loudspeaker of the present embodiment described above, horns of substantially two kinds of lengths are formed, and there is no large valley in the low frequency range in the radiated sound of the loudspeaker. Thus, the frequency characteristics are improved. Further, since an LCR circuit such as a multi-way speaker is not required, there is no energy loss due to such an LCR circuit, and the phase characteristics are not impaired. Therefore, the input signal can be faithfully reproduced. In addition, since only one speaker unit is required and two types of horns share a sound path, the size and weight can be reduced.
[0031]
Note that the speaker of the present invention is not limited to those shown in FIGS. In FIG. 3, the bent horn 30 communicates with the upper part of the speaker room 20. However, for example, the horn 30 may be configured to communicate with the lower part of the speaker room 20. Further, the horn 30 may be formed in other shapes such as a spiral shape in addition to the bent shape. Further, in FIG. 3, the slit 40 is formed so as to be sandwiched between the upper end surface of the back plate 22 of the speaker room 20 and the upper surface plate 23. A slit may be formed so as to be sandwiched between the lower end surface of the back plate 22 of the chamber 20 and the bottom plate 24. In FIG. 4, the lower side of the slit 40 is slidable. For example, the upper side of the slit may be slidable, or both the upper and lower sides of the slit may be slidable.
[0032]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the speaker of this invention, an input signal can be faithfully reproduced, without impairing a phase characteristic and a frequency characteristic. Also, it can be manufactured small and lightweight.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining the principle of a speaker according to the present invention.
FIG. 2 is a diagram provided for explaining a frequency characteristic of the speaker according to the present invention.
3A is a cross-sectional view of a speaker according to an embodiment of the present invention, FIG. 3B is a cross-sectional view of a main part showing a periphery of a slit, and FIG.
FIG. 4 is a cross-sectional view of the vicinity of the slit when the slit is a slide type.
FIGS. 5 (a), (b) and (c) show the case where the ratio d / D between the slit width d and the width D of the horn inlet is 1.00, 0.85 and 0.44, respectively. 3 shows the frequency characteristics of the radiated sound.
FIGS. 6 (a), (b) and (c) show the case where the ratio d / D between the slit width d and the width D of the horn inlet is 0.20, 0.09 and 0.03, respectively. 3 shows the frequency characteristics of the radiated sound.
FIG. 7 is a cross-sectional view showing a conventional speaker.
FIG. 8 is a diagram provided for explanation of frequency characteristics of a conventional speaker.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Speaker unit, 20 ... Speaker room, 21 ... Speaker room front plate, 22 ... Speaker room back plate, 23 ... Speaker room top plate, 24 ... Speaker room bottom plate, 30 ... Horn ( 1st horn), 31 ... horn entrance, 33 ... horn opening, 40 ... slit, 50 ... movable plate

Claims (3)

In a speaker including a speaker room to which a speaker unit that converts an electric signal into air vibration is attached, and a horn having an entrance portion connected to the speaker room through a communication port,
The communication port is provided with a sound radiated from the opening of the horn based on a length (L + Lsp) obtained by adding a length Lsp of the loudspeaker chamber to a length L of the horn. A speaker having an opening area smaller than an entrance of the horn so as to fill a valley of the horn, and a slit narrowed with respect to the entrance. The speaker chamber has a vertically long shape in which a distance between a top plate and a bottom plate opposed vertically is longer than a gap between a front plate on which the speaker unit is mounted and a back plate facing the front plate. The speaker according to claim 1, wherein the face plate forms the slit with one of the top plate and the bottom plate. The speaker according to claim 1, wherein a ratio d / D of a width d of the slit to a width D of an entrance of the horn is 0.09 to 0.2.

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