JPH0667028B2 - Vibration plate for speakers - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm of a speaker used as an audio output device for a cassette tape recorder, a microcassette tape recorder, a hi-fi stereo or a timepiece.

2. Description of the Related Art In recent years, cassette tape recorders, microcassette tape recorders, high-fidelity stereos, and the timepiece industry tend to be lighter, thinner, and smaller in size. Along with this, the speaker as an audio output device is also being reduced in weight, thickness and size.

Further, in terms of acoustic characteristics, there is a demand for a speaker that is more excellent in output sound pressure, distortion, and flatness than ever before, and speaker diaphragms that influence acoustic characteristics are becoming more and more important.

An example of the above-described conventional speaker will be described below with reference to the drawings.

FIG. 2 shows a sectional view of a vibration system of a conventional speaker. In FIG. 2, 1 is a diaphragm, 2 is a voice coil bobbin whose tip is fixed to the diaphragm 1, and 3 is a voice coil inserted into a magnetic gap (not shown) of a magnetic circuit.

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

As shown in FIG. 2, the speaker includes a vibration system such as a diaphragm 1, a voice coil bobbin 2, and a voice coil 3 and a magnetic circuit system (not shown) including a magnet, a pole, a plate, and a yoke. When a voice current flows through the voice coil 2 in a uniform magnetic field, a vertical electromagnetic force is generated in the voice coil 2 and vibrates in accordance with the current. This vibration is correctly transmitted to the vibration of the diaphragm 1 and radiated as a sound wave.

(For example, an introduction to acoustic engineering by Toshio Hayasaka, Nikkan Kogyo Shimbun) Problems to be solved by the invention It is ideal that the diaphragm of the speaker moves in a piston over the frequency band used, and the diaphragm is deformed or split during vibration. When vibration occurs, sound pressure-frequency characteristics, distortion rate, phase characteristics, etc. are deteriorated, which hinders high fidelity reproduction. Further, the conventional paper cone diaphragm, plastic diaphragm, and metal thin film diaphragm have a heavy diaphragm weight, and it is not possible to obtain a large output sound pressure. In addition, the weight variation of the diaphragm is large,
(For example, ± 10%) There was a problem in quality control.

In view of the above problems, the present invention provides a diaphragm for a speaker that does not deform or generate divided vibration during vibration, has a small vibration weight, and has a small weight variation.

Means for Solving the Problems To achieve this object, the speaker diaphragm of the present invention is formed by depositing a small amount of an organic solvent containing a fatty acid on a water surface and accumulating an arrayed film on a solid substrate. The solid film and Langmuir film (LB film) are used as the diaphragm.

It has long been known that molecules are aligned at the water-air interface when a small amount of an organic solvent containing a fatty acid or the like is dropped onto the water surface, and detailed studies have been made by Langmuir and Blodgett et al. The film accumulated on the substrate is called an LB film.

Action This LB film can form a highly oriented film by applying pressure in the horizontal direction in a state of being arranged at the water-air interface. Therefore, when this film is used as a diaphragm, the bending rigidity is very large because the molecules are oriented in the direction perpendicular to the film surface, and the diaphragm is not deformed or divided during vibration, resulting in an excellent sound wave. A speaker having frequency characteristics, distortion rate, and phase characteristics can be obtained. Further, since a method of accumulating monomolecular films to form a thick film is used, an extremely thin film can be formed. Therefore, the weight of the vibration system is reduced, and a large output sound pressure can be obtained. The thickness of the film itself is LB
Since it is determined by the length of the molecules that make up the membrane, the thickness of the membrane can be controlled on the order of several Å by changing the molecular chain length.

Therefore, the weight variation of the diaphragm is very small.

Example Hereinafter, regarding the speaker diaphragm of one example of the present invention,
A description will be given with reference to the drawings.

FIG. 1 is a sectional view of a speaker according to an embodiment of the present invention. In FIG. 1, 4 is a diaphragm using an L-B film, 5 is a voice coil bobbin whose tip is fixed to the diaphragm 4, and 6 is a voice coil inserted into a magnetic gap (not shown) of a magnetic circuit. is there.

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

As shown in FIG. 1, the speaker comprises a vibration system such as a flat diaphragm 4, a voice coil bobbin 5, and a voice coil 6, and a magnetic circuit system (not shown) including a magnet, a pole, a plate and a yoke. When a voice current flows through the voice coil 6 in a uniform magnetic field, a vertical electromagnetic force is generated in the voice coil 6 and vibrates in accordance with the current. This vibration is correctly transmitted to the vibration of the flat diaphragm 4, and is radiated as a sound wave.

Next, a method of manufacturing the diaphragm 4 will be described.

Β-Panaric acid (C ₂ H ₅ (CH═CH) ₄ (CH ₂ ) ₇ COOH) was used as the diaphragm material. Hereinafter, β-panaric acid is abbreviated as PA.

PA has a skeleton similar to that of stearic acid and has a molecular structure containing a conjugated double bond inside. This PA is 10 ^-2 M
Was dissolved in chloroform at a concentration of 3 to develop, and an LB film was accumulated on an aluminum foil as a solid substrate to give a final LB film thickness of 1 μm. Next, the double bond in PA was crosslinked with an electron beam to make the molecule three-dimensional. Then, it was dipped in a 20% sodium hydroxide solution to completely remove aluminum, and a vibration plate was obtained.

As a result, the physical property values shown in Table 1 were obtained.

As described above, according to this embodiment, L- made of PA is used.
In the speaker using the electron beam cross-linking diaphragm 4 of the B film, due to the molecular orientation effect of the L-B film, good vibration characteristics were obtained without deformation of the diaphragm and split resonance, and the distortion rate was reduced by 25 dB.
(Comparison with the polyester plastic diaphragm) Also, the output sound pressure increased by about 5 dB because the diaphragm became lighter. The variation in film thickness was below the detection limit of the measuring device.

EFFECTS OF THE INVENTION As described above, the present invention uses a Langmuir film as a speaker diaphragm, which is a solid film formed by accumulating a film dropped on a water surface on a solid substrate. It is possible to obtain a loudspeaker having a large output and realize an excellent loudspeaker having good acoustic characteristics.
Further, there is little variation in the weight of the diaphragm, and there are few problems in quality control. Also, since the diaphragm has a flat plate shape,
The speaker unit can be made thinner.

[Brief description of drawings]

FIG. 1 is a sectional view of a speaker diaphragm according to an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional speaker diaphragm. 4 ... Vibration plate, 5 ... Voice coil bobbin, 6 ... Voice coil.

Claims (2)

[Claims] 1. A diaphragm for a loudspeaker, comprising a Langmuir film of β-panaric acid and a cumulative film in which a double bond of β-panaric acid is cross-linked by electron beam irradiation. 2. The speaker diaphragm according to claim 1, wherein a flat Langmuir film is used.