JP2007060529A - Phase inverted speaker cabinet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phase inverted speaker cabinet comprising a duct that can be disposed within the cabinet while maintaining a length required for design. <P>SOLUTION: The present invention relates to a phase inverted speaker cabinet comprising a duct 3 communicating the inside and outside of a cabinet body 2, in the cabinet body 2 to which speaker units 4, 5 are attached. The duct 3 is configured by connecting, with a pipe joint 32, straight pipes 31, 31 selected based on the capacity of the cabinet body or the like. In particular, the pipe joint 32 is a box type of which an internal cavity portion has a greater cross-sectional area than an opening area of the pipes 31, 31 to be connected to the pipe joint, and a sound absorber 33 is housed therein. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a speaker system that converts electrical signals into acoustic energy, and in particular, inverts the phase of sound waves emitted from the back surface of the speaker unit, and enhances bass by matching the phases with sound waves emitted from the front surface of the speaker unit. The present invention relates to a phase-inverted speaker cabinet having a configuration as described above.

  The speaker system is composed of a unit and a cabinet (enclosure). The speaker units constituting the speaker system are divided into a full range, a tweeter, a mid range, and a woofer according to a reproduction band. On the other hand, as a cabinet to which a speaker unit is attached, a sealed type or a phase inversion type (bass reflex type) is known depending on its form.

  In the phase inversion type, an opening (port) is mainly provided on a part of the unit mounting surface (baffle plate), and a pipe-shaped duct that forms a sound path is connected to the opening, or a duct is connected to the unit mounting surface. Molded integrally, reverses the phase of the sound wave radiated from the back of the unit through its duct, leads it to the front of the cabinet, and combines it with the sound wave radiated from the front of the unit to increase the efficiency of the low range Compared to the sealed type, there is an advantage that the sound pressure level in the low frequency band can be increased.

  However, below the resonance frequency of the duct, the phase of the sound radiated from the unit and the duct is reversed, and the bass reproduction capability is lost. For this reason, the resonance frequency of the duct is designed to be much lower than the resonance frequency of the unit.

  Since the resonance frequency becomes lower as the internal volume of the cabinet is larger and the duct is longer, in order to increase the bass reproduction capability, the cabinet needs a corresponding depth to provide a longer duct, but it is called a bookshelf It is difficult to install a long duct in a small cabinet.

  Conventionally, a bent duct having a predetermined shape is also formed by using a mold in order to accommodate a duct having a length required for design in a cabinet having a limited volume. It is not easy to mold the duct, and in addition, it costs high to produce a dedicated mold each time.

  Therefore, a duct made of a hard ethylene propylene rubber tube has been proposed as a duct that can be easily molded into a predetermined shape while having one or more bent portions (for example, Patent Document 1).

Japanese Patent No. 2767905

  However, according to Patent Document 1, hard ethylene / propylene rubber is extruded from a nozzle to form a tube body, which is inserted into a crank-shaped jig and vulcanized, and then the jig is pulled out to form a crank shape. Therefore, it is not easy to mold such a duct.

  In particular, if the bent portion has a single L shape, it is easy to pull out the jig, but if there are two or more bent portions, it is not possible to pull out the jig after vulcanizing the hard ethylene / propylene rubber. It is very difficult.

  The present invention has been made in view of the above circumstances, and its purpose is a phase-inverted speaker cabinet, and a duct that can be placed in a cabinet while having a length required for design. Is to be easily obtained.

  In order to achieve the above object, the present invention provides a phase-reversed speaker cabinet in which a cabinet body to which a speaker unit is attached is provided with a duct that communicates the inside and outside of the cabinet. The duct connects at least two pipes and the pipes. And a pipe joint.

  In the phase-inverted speaker cabinet as described above, the pipe joint is characterized in that the internal cavity portion has a larger cross-sectional area than the opening area of the pipe connected thereto. In addition, a sound absorbing material is accommodated in the pipe joint.

  According to the phase inversion type speaker cabinet according to the present invention, since the duct is constituted by at least two pipes and a pipe joint for connecting the pipes, the duct molding is performed each time according to the form of the cabinet body. Without producing a mold, it is possible to easily form a duct with the length required for the design by combining the pipes, and connecting the pipes in a bent state according to the internal shape of the cabinet body, etc. A duct having a predetermined shape that can be arranged in the cabinet body can be easily assembled.

  In particular, it is possible to appropriately perform tuning so as to obtain a bass that is optimal for hearing, by simply changing the combination of pipes.

  In addition, since the pipe joint is a joint having an inner cavity portion having a larger cross-sectional area than the opening cross section of the pipe, the pipe joint functions as an acoustic filter for reducing the sound pressure in the mid and high range, so that sound leakage in the mid and high range is achieved. Can be prevented and the low frequency range can be cleared in terms of hearing.

  In particular, since the sound absorbing material is accommodated in the pipe joint, it is possible to further improve the effect of preventing mid-high sound leakage and wind noise at the duct outlet portion.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 shows a configuration example of a speaker system using a phase inversion type speaker cabinet according to the present invention. In FIG. 1, reference numeral 1 denotes such a phase inversion type speaker cabinet, and the cabinet 1 is composed of a cabinet body 2 and a duct 3 disposed therein.

  In this example, the cabinet body 2 has a rectangular shape configured by combining a front surface portion 21 (baffle plate) made of a wood board or the like, a back surface portion 22, a pair of left and right side surface portions 23, an upper surface portion 24, and a bottom surface portion 25. Therefore, an opening 26 (port) is formed in the front surface portion 21 thereof.

  Two speaker units 4 and 5 are attached to the front surface portion 21 of the cabinet body 2 to constitute a two-way speaker system.

  One speaker unit 4 is a tweeter, and the other speaker unit 5 is a woofer. A mid range is added to this to make a 3-5 way speaker system, or the speaker unit is a single structure of a full range. May be. Of course, even a two-way structure may be composed of two woofers and one tweeter.

  Further, the cabinet body 2 is not limited to a rectangular shape, and two molded bodies molded into a concave shape from a synthetic resin or the like are joined to form a structure having a rounded oval cross section as a whole. You can also

  On the other hand, the duct 3 acoustically communicates the inside and outside of the cabinet body 2, one end of which is connected to the opening 26 of the cabinet body 2 and the other end is opened inside the cabinet body 2.

  In particular, the duct 3 includes a plurality of straight pipes 31 whose axial centers are linear, and pipe joints 32 that connect and communicate the pipes 31.

  FIG. 1 shows an example in which two straight pipes 31 having the same opening area (diameter) are connected at right angles by a pipe joint 32, but this may be a connection form as shown in FIGS. Good.

  2 shows a configuration in which two straight pipes 31 having different opening areas are connected at right angles by a pipe joint 32, and FIG. 3 shows a configuration in which two straight pipes 31 having different opening areas are connected in series by a pipe joint 32, FIG. Is a configuration in which two straight pipes 31 are obliquely connected to each other by a pipe joint 32 in a non-perpendicular state (obtuse angle state). FIG. 5 shows three straight pipes 31 that are obliquely connected to each other by two pipe joints 32 in an obtuse angle shape. It is a configuration.

  Here, the pipes 31 are round pipes having a circular cross section made of paper or synthetic resin. However, these pipes 31 may be elliptic pipes having an elliptical cross section, or square pipes having a square or rectangular cross section.

  On the other hand, the pipe joint 32 is a box shape in which the internal cavity portion has a larger cross-sectional area than the opening area of the pipe 31, and this is a connection port for connecting each end of the two straight pipes 31 as shown in FIG. 32A and 32B are formed.

  In the figure, the connection ports 32A and 32B of the pipe 31 and the pipe joint are in a plug-in connection form, but this may be a flange-type connection form or a screw-type connection form. In addition, when the opening area (diameter) of the two pipes 31 and 31 connected to the pipe joint is different from that of the pipe joint having an inner cavity portion larger than the opening area of the pipe, the opening area (arbitrary crossing) This means that the internal cavity portion has a larger cross-sectional area than the larger opening area in the surface. However, the pipe joint is not limited to the box shape, and may be a hollow sphere.

  As apparent from FIG. 1, a sound absorbing material 33 made of glass wool or the like is accommodated in the pipe joint.

  According to such a pipe joint 32, the straight pipe 31 can be connected at a predetermined angle, and this forms a hollow portion of a predetermined volume which swells from the pipe 31, so that the sound in the middle and high range can be internally generated. Can be prevented from leaking wind noise and middle / high sound, and the sound absorbing material 33 further improves the effect of preventing middle / high sound leakage.

  In other words, the sound radiated from the duct 3 inherently includes middle and high frequency components and harmonic distortion, which cause turbidity (noise) of the low frequency sound. According to the duct 3 having the pipe joint 32 that accommodates 33, the above noise can be cut by the acoustic filter effect (low-pass filter), and a clear low-frequency sound can be obtained.

  In the illustrated example, the sound absorbing material 33 is fixed to the inner wall of the pipe joint 32. However, the sound absorbing material 33 may be filled in the pipe joint 32.

  The duct 3 as described above has its entire length including the pipe joint 32 determined based on the resonance frequency of the speaker unit 5 for bass and the internal volume of the cabinet body 2. The efficiency of the low frequency range can be increased by inverting the phase of the sound wave radiated into the cabinet body 2 and guiding it to the front of the cabinet body 2 and synthesizing it with the sound wave radiated from the front surface of the speaker unit 5.

Incidentally, the length L of the duct 3 is obtained by L = (25600S / (f ² × V); S is the opening area of the duct, f is the resonance frequency of the duct, and V is the volume of the cabinet body).

  Here, the phase inversion type speaker cabinet according to the present invention includes a plurality of pipes 31 (including straight pipes and bent pipes) having different opening areas (bore diameters) and lengths, and two connection ports 32A and 32B. A group of parts composed of a plurality of box-shaped pipe joints 32 having different relative positions, open areas, and volumes of hollow portions is prepared in advance, and based on the resonance frequency of the speaker unit 5 and the internal volume of the cabinet body 2 from the parts group. It is easy to select a predetermined pipe 31 and pipe joint 32 adapted to the volume and length of the duct 3 determined in combination, and combine them as the duct 3 and connect one end thereof to the opening 26 of the cabinet body 2. Can be configured.

Two pipes 31 (straight pipes) are connected at right angles by a pipe joint 32 to form a duct 3, and one end thereof is connected to the opening 26 of the cabinet body 2 to produce a phase inversion speaker cabinet 1 as shown in FIG. did. Here, the volume of the cabinet body 1 is 295 cm ³ , the two straight pipes 31 are round pipes having the same opening area (23 cm ² ), one (opening 26 side) is 1 cm in length, the other is 9 cm, pipe joint Reference numeral 32 denotes a box shape in which the cross-sectional area (arbitrary cross-sectional area) of the internal cavity portion is 11 cm ² and the volume is 37 cm ³ , and the inside thereof is filled with glass wool as the sound absorbing material 33.

  And the speaker units 4 and 5 were attached to this, and the noise level in the exit of the duct 3 was measured. The result is shown in FIG.

  On the other hand, as a comparative example, FIG. 7 shows the result when the duct is replaced with a conventional duct (one integrally molded at a right angle).

  As apparent from FIGS. 6 and 7, the noise level of the duct of the phase inversion type speaker cabinet according to the present invention is greatly reduced in the mid-high frequency band (about 500 Hz in this experiment) as compared with the conventional duct. I understand.

  Although the present invention has been described above, the duct 3 is not limited to being disposed inside the cabinet body 2 and may be provided outside the cabinet body 2.

  Further, in the embodiment, the straight pipe is described, but the present invention is not limited to this, and a pipe having a curvature may be used. However, straight pipes are most preferred because they are highly productive and inexpensive.

Explanatory drawing which shows the internal structure of the phase inversion type | mold speaker cabinet based on this invention. Explanatory drawing which shows the modification of this invention Explanatory drawing which shows the modification of this invention Explanatory drawing which shows the example of a change of this invention Explanatory drawing which shows the example of a change of this invention The graph which shows the noise spectrum by the duct which concerns on this invention Graph showing noise spectrum due to conventional duct

Explanation of symbols

1 Phase-inverted speaker cabinet 2 Cabinet body 26 Opening (port)
3 Duct 31 Pipe 32 Pipe joint 32A, 32B Pipe connection port 33 Sound absorbing material

Claims (3)

In the phase inversion type speaker cabinet provided with a duct communicating with the inside and outside of the cabinet body to which the speaker unit is attached,
The phase inversion type speaker cabinet, wherein the duct includes at least two pipes and a pipe joint connecting the pipes.   2. The phase inversion type speaker cabinet according to claim 1, wherein the pipe joint is a joint having an inner cavity portion having a cross-sectional area larger than an opening area of a pipe connected to the pipe joint. The phase reversal type speaker cabinet according to claim 2, wherein a sound absorbing material is accommodated in the pipe joint.

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