JPS62172900A - Speaker - Google Patents

Abstract

PURPOSE:To attain reproduction over a full range from a low-pitched sound to a high-pitched sound by linking the first air chamber consisting of the first frame, a diaphragm, and a magnetic circuit, etc., with the second air chamber consisting of the second diaphragm, a bellows, and the magnetic circuits, etc., with an air hole. CONSTITUTION:When a signal current is conducted in a voice coil inserted to a magnetic gap, a driving force is generated, and the voice coil 14 vibrates in up and down, and also, the first diaphragm 17 vibrates, thereby a sound being generated. At such a time, since the volume of the first air chamber 22 is varied, the volume of the second air chamber 23 linked to the first air chamber with an air hole 19 is also varied, and corresponding to the above, a bellows 20 is extended/compressed and vibrates, therefore, the second diaphragm 21 vibrates, and a sound wave is radiated through a slit 27, thereby generating the sound. Assuming that the area of the diaphragm 17 is as A1, and the cross section of the bellows 20 as A2, the displacement quantity of the diaphragm 21 is expanded in the A1/A2-fold of the displacement quantity of the diaphragm 17. The air chambers 22 and 23 are formed in a closed relation, and no leakage of the air is generated, therefore, the reproduction of the sound can be performed efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to the improvement of speakers, and particularly to speakers that amplify the small amplitude of a vibration source such as a voice coil using amplitude amplification means and transmit the amplified amplitude to a diaphragm. It is related to.

2. Description of the Related Art In recent years, audio equipment has been required to be smaller and have higher performance, and speaker systems are also becoming smaller, but there is a problem with bass reproduction. The axial sound pressure (Pr) and amplitude (x) of the speaker are expressed by the following equations.

・・・・・・・・・(2) Here ρ. : Air density, ω: Vibration angular frequency, a: Effective radius of diaphragm, r: Distance between speaker and microphone, V: Velocity of diaphragm, X: Amplitude of diaphragm, A: Force coefficient, E: Signal Input voltage, RE: electrical resistance of the speaker, Mll: mass of the vibration system of the speaker, Ma: load mass of air, Qo: sharpness of resonance, fo: lowest resonance frequency, f: frequency.

Therefore, as the effective radius of the diaphragm becomes smaller, efficiency decreases. However, according to equation (2), the amplitude of the diaphragm is inversely proportional to the square of the frequency above f0, so it becomes large at low acoustic frequencies.

However, if the winding width of the voice coil is made smaller in order to improve efficiency, the amplitude range of the voice coil becomes narrower, resulting in the generation of distortion components due to low sonic acid. For this reason, there is a speaker using a long voice coil as a method that allows for a large amplitude, but it has the disadvantage that the utilization rate of the voice coil is poor and the efficiency is low.

Therefore, in order to improve efficiency and reduce distortion, it is necessary to amplify the small amplitude of the voice coil and transmit it to the diaphragm.

As a conventional technique, for example, as shown in Japanese Patent Publication No. 56-131298, there is a technique using a hydraulic pressure transmission device using a cylinder and a piston.

The conventional speaker as described above will be described below with reference to the drawings.

FIG. 2 is a schematic cross-sectional view of a conventional speaker using an amplitude amplification mechanism using a hydraulic power transmission device. In Figure 2, 1
is the center pole, 2 is the plate, 3 is the magnet, 4
5 is the voice coil inserted into the gap of the magnetic circuit made up of the center pole 1° plate with the lower end of the magnet 3, and 5 is the cross-sectional area S1 formed at the upper end of the voice coil.
The piston 6 has a cross-sectional area S formed at the lower end of the diaphragm 9.
2 is a piston, 7 is a cylinder with a piston 6 on the input side and a piston 6 on the output side, 8 is a fluid pressure transmission device consisting of a tobacco cylinder 7 and pistons 5 and 6, 10 is the outer peripheral end of the diaphragm 9 This is an edge whose inner peripheral end is glued to the frame and whose outer peripheral end is fixed to a frame (not shown).

The operation of the conventional speaker configured as described above will be described below.

Center pole 1. Plate 2. When a signal current flows through the voice coil 4 located in the magnetic gap formed by the magnet 3, a force is applied to the voice coil 4 according to Fleming's left hand rule, causing it to vibrate up and down. At this time, the piston 5 formed in the voice coil 4 also vibrates, and the vibration of the piston 6 is amplified by S1/S2 times compared to the piston 5 by the hydraulic transmission device 8. Therefore, the diaphragm 9 fixed to the piston 6 is also amplified by a factor of S1/S2 compared to the displacement of the voice coil 4.

Problems to be Solved by the Invention However, with the above configuration, vibrations are transmitted through the fluid (usually air) of the hydraulic transmission device, so there is a drawback that it is difficult to transmit high frequency ranges. It is unsuitable as a full-range speaker that reproduces from bass to treble. Another drawback is that air leaks from the gap between the cylinder and the piston, resulting in a decrease in efficiency. Furthermore, if oil, which has a higher density (ρ) and sound velocity (C) than air, is used as the fluid in the cylinder to improve high-frequency characteristics, there are problems such as an increase in the load mass and a decrease in efficiency. This was not suitable as a speaker with an amplitude amplification mechanism.

In view of the above-mentioned problems, the present invention provides a speaker equipped with an amplitude amplification mechanism that efficiently reproduces high-fidelity sounds from the low to high range.

Means for Solving the Problems To achieve this object, the speaker of the present invention includes 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, and an end of a telescoping bellows having a diameter larger than the hole is fixed to the back surface of the magnetic circuit, and the other end is attached to a second A second air chamber is formed by being fixed to a diaphragm, and this second diaphragm is fixed to a second frame via a second edge, and a second air chamber is formed by being fixed to a diaphragm.
The frame is composed of an amplitude amplification mechanism having a structure surrounding the outer periphery while having a gap between it and the first frame.

Effect: With this configuration, when the voice coil moves, the volume of the first air chamber changes, and air moves from the second air chamber through the hole in the center of the magnetic circuit, changing the volume of the second air chamber (the bellows (corresponds by expanding and contracting) and the second
The diaphragm also moves.

At this time, the amount of movement of the second diaphragm is such that the cross-sectional area of the first diaphragm is A4. If the cross-sectional area of the bellows is A2, it will be expanded by A1/A2 times the amount of movement of the first diaphragm, resulting in better bass reproduction. Also the first
The vibration of the first diaphragm is transmitted to the second diaphragm through the air, and it may be difficult to transmit the high frequency range, but the treble range can be directly radiated by the first diaphragm. This makes it possible to realize a full-range speaker equipped with an amplitude amplification mechanism. Furthermore, the first. The second air chamber is constructed by surrounding it with a first diaphragm, a first edge, a first frame, a bellows, and a second diaphragm, and is a conventional amplitude amplification mechanism using a piston and a cylinder. It is highly airtight with no gaps and no air leakage, allowing efficient vibration transmission.

EXAMPLE An example of the present invention will be described below with reference to the drawings. FIG. 1 shows a sectional view of a speaker in one embodiment of the present invention. In FIG. 1, 11 is a center pole, 12 is a plate, 13 is a magnet, and 14 is a lower end of the center pole 11. Plate 1: A voice coil bobbin with a voice coil (not shown) inserted into the magnetic gap formed by the magnet 13 at its tip;
15 is a first frame; 16 is a damper whose outer peripheral end is fixed to the first frame 15 and whose inner peripheral end is fixed to the voice coil bobbin 14 through which air can freely circulate; 17 is a first diaphragm; and 18 is an inner damper. The peripheral end is fixed to the outer peripheral end of the first diaphragm 17,
a first edge whose outer peripheral end is fixed to the first frame 16;
19 is an air hole provided approximately in the center of the magnetic circuit; 20 is an expandable bellows larger than the diameter of the air hole 19 and whose upper end is fixed to the back of the center pole 11 and whose lower end is fixed to the second diaphragm 21; , 22 are first frame 11: first edge 18. A first diaphragm 17 and a first diaphragm surrounded by a magnetic circuit.
23 is a second air chamber surrounded by the bellows 2o, the second diaphragm 21, and a magnetic circuit; 24 is a connecting rod 26 surrounding the outer periphery with a gap between it and the first frame 16; A second frame 26 is fixed to the first seven frames 16 and allows air to freely enter and exit through slits 27.
is a second edge whose inner peripheral end is fixed to the outer peripheral end of the second diaphragm 21 and whose outer peripheral end is fixed to the second frame 24. The operation of the speaker configured as above will be explained below.

First, when a signal current is passed through the voice coil inserted into the magnetic gap, a driving force is generated according to Fleming's left hand rule, causing the voice coil bobbin 14 to vibrate up and down, and the first diaphragm 17 to vibrate, producing sound. . At this time, since the volume of the first air chamber 22 changes, the volume of the second air chamber 23 connected by the air hole 19 also changes, and the bellows 2o expands and contracts according to this volume change, causing the second air chamber 22 to change. The diaphragm 21 of the diaphragm 21 vibrates, and the generated sound wave (first
A sound wave having the same phase as that generated by the diaphragm is radiated through the slit 27 to generate sound.

As described above, according to this embodiment, the first diaphragm 17 and the second diaphragm
The diaphragm 21 is connected by a fluid pressure transmission device consisting of a piston and a cylinder, so the area of the first diaphragm is A1. When the cross-sectional area of the bellows 20 is A2, the amount of displacement of the second diaphragm 21 is A1 of the amount of displacement of the first diaphragm 17.
/A will be enlarged twice. In addition, since the mechanism transmits vibrations through air, it becomes difficult to transmit vibrations when the frequency is high a, and the second diaphragm 21 does not vibrate in the high frequency range.
Since the first diaphragm 17 has a structure that can radiate sound, it is possible to improve the drawback that high frequency range cannot be reproduced unlike a conventional speaker having an amplitude amplification mechanism using a fluid pressure transmission device. Furthermore, in the past, air leaked from the gap between the piston and the cylinder, resulting in poor efficiency; however, according to this embodiment, the first air chamber 22. The second air chamber 23 is a closed system, and since no air leaks, sound can be reproduced efficiently.

In this embodiment, the first diaphragm 17 is of a cone shape,
Although the second diaphragm 21 is shaped like a flat plate, it can be freely changed into a cone-shaped flat plate or other shapes.

Effects of the Invention The present invention includes a first air chamber surrounded by a first frame, a first edge, a first diaphragm, and a magnetic circuit, and a first air chamber surrounded by an expandable bellows, a second diaphragm, and a magnetic circuit. The amplitude amplification mechanism is connected to a second air chamber by an air hole, and has a closed system in which the amplitude is amplified by the ratio of the area of the first diaphragm to the cross-sectional area of the bellows. Unlike a speaker with an amplitude amplification mechanism consisting of a speaker, air leakage does not occur from the gap between the cylinder and the piston, so highly efficient reproduction is possible.

In addition, conventional speakers that transmit vibrations through fluid such as air and amplify the amplitude cannot transmit high-frequency vibrations, making it impossible to reproduce high-frequency sounds.However, in the present invention, the first vibration The plate is directly driven by the voice coil, so it can reproduce high frequencies, and the second diaphragm, which amplifies the amplitude through air, can reproduce low frequencies, so one speaker unit can cover the full range from low to high. This makes it possible to realize an excellent speaker that can reproduce sound.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a speaker in an embodiment of the present invention;
FIG. 2 is a sectional view of a conventional speaker. 11... Center pole, 12... Plate, 13... Magnet, 14...
・Voice coil bobbin 15...First frame, 16...Damper, 17...First diaphragm, 18...First edge, 19・・・・・・
...Air hole, 20...Bellows, 21...
...Second diaphragm, 22...First air chamber, 2
3...Second air chamber, 24...Second frame, 26...Second edge, 26...
...Connecting rod. Name of agent: Patent attorney Satoshi Nakao, and one other person. f5 Ichiban IQ Ru 4 f6---Dan to'- f9-11 empty car bite 20----, -Rose 21-Ichiban 2's son Kafusu 22---y) ζ 1 Air / Do 23+-1 2nd Li 〃 24-1 tile 2s 7L-4 25-11 Tobi 24 Elli 26 series connecting rod Fig. 2

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 in the center of the magnetic circuit; A second air chamber is formed by 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 through the hole. The second diaphragm is fixed to a second frame via a second edge, and the second frame has an outer periphery with a gap between it and the first frame. box, the second frame is fixed to the first frame, and the speaker includes an amplitude amplification mechanism.