JPS6382098A - Speaker system - Google Patents

Abstract

PURPOSE:To improve radiation efficiency in a low frequency range and to flatten sound pressure and frequency characteristics in an intermediate and a high frequency range by providing plural partition plates in the back cabinet of a speaker unit, constituting an acoustic pipe extended continuously from the back surface of the speaker unit by using the partition plates, and forming the opening of the acoustic tube in part of the external wall of the cabinet. CONSTITUTION:When a signal current is supplied to a voice coil 8, the voice coil 8 vibrates upward and downward and the 1st diaphragm 11 vibrates to generate a sound. At this time, a 1st air chamber 16 varies in capacity, so the capacity of a 2nd air chamber 17 linked by an air hole 13. A bellows 14 expands and shrinks according to the capacity variation and a 2nd diaphragm 15 vibrates to radiate the sound to the back surface of the speaker unit. At this time, vibrations are transmitted through air, so a high frequency sound is hardly transmitted and only a low frequency sound is radiated to the back surface. Consequently, a half-wavelength sound is transmitted in the acoustic tube in the low frequency range to cause resonance and sounds radiated by the front surface of the 1st diaphragm 11 and the rear surface of the 2nd diaphragm 15 becomes in phase with each other and are put added, so that the sound pressure level increases.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to improvements in loudspeakers, and more particularly to loudspeaker systems having acoustic labyrinth cabinets.

BACKGROUND OF THE INVENTION One of the conventional techniques for expanding the bass reproduction range of a speaker system is an acoustic maze type.

Hereinafter, a conventional acoustic maze type speaker system will be explained with reference to the drawings.

In FIG. 2, 1 is a cabinet and 2a.

2b and 20 are partition plates provided on the front panel 1a and rear panel 1b in the cabinet 1, 3 is an opening provided at the bottom of the front panel 1+L of the cabinet 1, and 4 is a speaker provided at the top of the front panel 1a. It is a unit.

The operation of the acoustic labyrinth type speaker system configured as described above will be described below.

A partition plate 2a provided inside the cabinet 1.

2b and 20 constitute acoustic tubes, and the sound emitted from the rear surface of the speaker unit 4 is guided to the acoustic tube and radiated through the opening 3. The acoustic tube generates resonance at a frequency determined by its total length, and when a half wavelength is added to this and causes resonance, the sound in front of the speaker unit 4 is inherently out of phase compared to the sound from the front. The sound emitted from the rear side of the speaker unit 4 from the opening 3 of the acoustic tube becomes in-phase due to a half-wavelength phase delay, and the sound pressure level increases, for example, the sound pressure level of 501-12. To raise 3.
The partition plates 2a and 2b require a length of 4 m.

If a labyrinth was constructed using 2G, it would be possible to fit a predetermined acoustic tube within the cabinet 1 with a limited volume, and the bass reproduction area of a small speaker system could be expanded.

Problems to be Solved by the Invention However, in the above configuration, when the frequency increases and one wavelength is placed on the acoustic tube and resonance occurs, the sound radiated from the front of the speaker unit 4 and the acoustic tube The sound emitted from the rear side of the speaker unit 4 through the opening 3 of the speaker unit 4 has opposite phases and cancels each other out, resulting in a large dip in sound pressure, and the sound pressure frequency characteristic has peaks and dips as shown in Fig. 3. This could not be called high-fidelity playback.

In view of the above-mentioned problems, the present invention provides an acoustic labyrinth type speaker system that improves the radiation efficiency in the bass range and has flat sound pressure frequency characteristics in the middle and high frequencies.

Means for Solving the Problems To achieve this object, the speaker system of the present invention includes a first frame, a first edge, a first diaphragm, and a first air chamber surrounded by a magnetic circuit; By providing a hole approximately in the center of the magnetic circuit, and further fixing an end of an expandable bellows having a diameter larger than the hole to the back surface of the magnetic circuit, and fixing the other end to the second diaphragm. A second air chamber is configured, and the second diaphragm is fixed to a second frame via a second edge. enclosing the second frame, the second frame has a speaker unit configured to be fixed to the first frame, and a plurality of partition plates are provided in the cabinet on the back of the speaker unit,
The partition plate constitutes an acoustic tube extending continuously from the rear surface of the speaker unit, and the opening thereof is provided in a part of the outer wall of the cabinet.

Effect: With this configuration, half a wavelength resonates in the acoustic tube installed on the back of the speaker unit, and the sound from the front of the speaker unit and the sound from the back of the speaker unit radiated from the opening of the acoustic tube are in phase and add to each other, producing low-frequency sounds. In addition to increasing the sound pressure level at High mid-to-high ranges are difficult to transmit, and only low-frequency ranges are emitted from the back of the speaker unit.
There is no dip and high fidelity reproduction is possible.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view of a speaker system in one embodiment of the present invention. In Fig. 1, 5 is a center pole, 6 is a plate, 7 is a magnet, and 8 is a voice coil whose lower end is inserted into the magnetic gap made up of the center pole 5, plate 6, and magnet 7, and the tip of the voice coil bobbin. It is set in. 9 is a first frame; 10 is a damper whose outer peripheral end is fixed to the first frame 9 and whose inner peripheral end is fixed to the voice coil bobbin, allowing free circulation of air; 11 is a first diaphragm; and 12 is an inner periphery. A first edge whose end is fixed to the outer peripheral end of the first diaphragm 11 and whose outer peripheral end is fixed to the first frame 9; 13 is an air hole provided approximately in the center of the magnetic circuit; 14 is an air hole 13; A telescopic bellows whose upper end is fixed to the back of the center pole 5 and whose lower end is fixed to the second diaphragm 15. a first air chamber surrounded by a diaphragm 11 and a magnetic circuit; 17 is a bellows 14;
and a second air chamber surrounded by a second diaphragm 16 and a magnetic circuit; 18 surrounds the outer circumference with a gap between it and the first frame 9; The second frame 19 is fixed to the slit 24 so that air can freely enter and exit through the slit 24, and the inner peripheral end thereof is fixed to the second diaphragm 15.
21 is a cabinet; 22a is a second edge fixed to the outer peripheral edge of the second frame 18;

22b and 22c are partition plates provided in the cabinet 21, and 23 is an opening provided in the front surface of the cabinet 21.

The operation of the speaker system configured as above will be explained below.

First, when a signal current is passed through the voice coil 8 inserted into the magnetic gap, a driving force is generated according to the left-hand rule of 7 Remy/G, causing the voice coil 8 to vibrate up and down and
The diaphragm 11 of vibrates and generates sound. At this time, the first
Since the volume of the second air chamber 16 changes, the volume of the second air chamber 17 connected by the air hole 13 also changes, and the bellows 14 expands and contracts in response to this volume change.
The second diaphragm 16 vibrates, and sound is radiated to the back of the speaker unit. At this time, since the vibrations are transmitted through the air, high frequencies are difficult to transmit and only low frequencies are radiated to the back.
A sound composed of a, 22b, and 22c! It passes through the tube and is emitted from the opening 23.

As described above, according to this embodiment, the sound emitted from the back of the speaker unit is transmitted through the air, so it passes through a kind of acoustic filter, meaning that only the low tones are transmitted and the high tones are not transmitted. radiated. Therefore, in the bass range, a half wavelength is placed on the acoustic tube, causing resonance, and the sound radiated from the front surface of the first diaphragm 11 and the back surface of the second diaphragm 15 radiated from the opening 23 of the acoustic tube. They are in phase, and the sound pressure level increases. Also, one wavelength is placed on the acoustic tube, causing resonance, and at 9 o'clock, the sound in front of the first diaphragm 11 and the sound radiated from the opening 23 of the acoustic tube are in opposite phase, cancel each other out, and the sound pressure level decreases. descend. In a conventional speaker system with a labyrinth-shaped cabinet, the sound pressure level increases or decreases, causing peaks and dips in the mid-to-high range as described above, but in this example, in the mid-to-high range, the rear This has the advantage that very flat sound pressure frequency characteristics can be obtained because there is no radiation of sound from the source and the sounds do not add up or cancel each other out depending on the phase.

In this embodiment, there is only one acoustic tube on the back of the speaker unit, but by providing a plurality of acoustic tubes with different lengths, reproduction of low frequency ranges is further improved.

Further, the shape of the sound tube can be freely changed, and the structure may be such that a horn effect can be obtained by continuously changing its cross-sectional area.

Effects of the Invention The present invention provides an acoustic tube on the back of a speaker unit, and utilizes this resonance to reproduce bass sounds well.
Especially the first thing about the speaker unit. Since the second two diaphragms are configured to vibrate through the air, it is possible to radiate the entire range from bass to treble from the front, and only radiate bass from the back. Therefore, in the mid-to-high range, there is no interference between the sound from the front of the speaker unit and the sound from the back from the acoustic tube opening, making it possible to flatten the sound pressure frequency response compared to conventional speakers, creating a speaker system with superior performance. This is something that can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a speaker system according to an embodiment of the present invention, FIG. 2 is a structural sectional view of a conventional speaker system, and FIG. 3 is a sound pressure frequency characteristic diagram of a conventional speaker system. 5... Center pole, 6... Plate, 7... Magnet, 8... Voice coil, 9... First frame, 10...・・・・・・
Damper, 11...First diaphragm, 12...
...First edge, 13... Air hole, 14.
...Bellows, 16...Second diaphragm,
16...First air chamber, 17...Second
Air chamber, 18...Second frame, 19...
...Second edge, 2o...Connection rod, 21
...Cabinet, 22a. 22b, 220...partition plate, 23...opening. Name of agent: Patent attorney Toshio Nakao and 1 other famous person 2
Figure 3

Claims (1)

[Claims] A first air chamber surrounded by a first frame, a first edge, a first diaphragm, and a magnetic circuit; a hole through which air can flow in and out is provided approximately at the center of the magnetic circuit; A second air chamber is formed by having one end of a retractable bellows having a diameter larger than the hole fixed to the back surface of the magnetic circuit, and the other end fixed to a second diaphragm. The second diaphragm is fixed to a second frame via a second edge, and the second frame extends at least around the outer periphery of the first frame while having a gap therebetween. a speaker unit configured to surround and be fixed to the first frame, a plurality of partition plates being provided in a cabinet on the back side of the speaker unit, and extending continuously from the back side of the speaker unit by the partition plates; What is claimed is: 1. A speaker system comprising an acoustic tube with an opening formed in a part of an outer wall of a cabinet.