JPS62289098A - Diaphragm for speaker - Google Patents

Abstract

PURPOSE:To obtain a high resonance frequency speaker diaphragm without causing deformation, division and vibration by using a formed thing made of sheets obtained by sticking a sheet made of polyamide prepreg on both sides of sheets made of polyamide prepreg. CONSTITUTION:A diaphragm 4, a voice coil bobbin 5 and a voice coil 6 comprise the diaphragm system of a speaker. The diaphragm is obtained in such a way that a three-layered sheet where the sheet made of polyimide prepreg is stuck to the both sides of the sheet made of polyamide prepreg is formed by heat press. Since the surface material has an extremely high bending regidity, the diaphragm never develops deformation, division and resonance during vibration. Since a core material provides great mechanical inner losses, there is less fluctuation in terms of a frequency characteristic. Therefore the speaker with an excellent sound pressure-frequency characteristic, an excellent distortion ratio and a phase characteristic can be obtained.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Field of Industrial Application The present invention relates to a diaphragm for a speaker used as an audio output device.

Conventional Technology In recent years, in the cassette tape recorder, micro-scent tape recorder, and high-fidelity stereo industries, speakers as sound output equipment have become increasingly popular in terms of their acoustic characteristics, with better output sound pressure, distortion rate, and flatness than ever before. 9. Speaker diaphragms, which influence acoustic characteristics, are becoming more and more important.

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

FIG. 2 shows a cross-sectional view of the 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 consists of a vibration system including a diaphragm 1, a voice coil bobbin 2, a voice coil 3, and a magnetic circuit system (not shown) including a magnet, pole, plate, and yoke. When an audio current flows through the voice coil 3 located in a uniform magnetic field, an electromagnetic force in the vertical direction is generated in the voice coil 3, and an image is taken 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, Hisao Hayasaka: Introduction to Acoustic Engineering, Nikkan Kogyo Shimbun).

Problems to be Solved by the Invention Ideally, the diaphragm of a speaker should move as a piston over the frequency band in use, and if the diaphragm deforms during vibration or split vibration occurs, the sound pressure-frequency characteristics and distortion will change. rate,
Phase characteristics etc. deteriorate, which impedes high-fidelity reproduction. Ti.

Conventional paper cone diaphragms and plastic diaphragms have low E/p (E: elastic modulus, ρ: density) of the diaphragm material, so the high-frequency resonance frequency is low and the speaker cannot reproduce high frequencies. There were drawbacks.

In view of the above-mentioned problems, the present invention provides a diaphragm for a speaker that does not deform or cause split vibration during vibration and has a high high resonance frequency.

Means for Solving the Problems In order to achieve this object, the speaker diaphragm of the present invention has a three-layer structure in which polyimide prepreg sheets are laminated on both sides of a polyamide prepreg sheet, and the sheets are laminated and bonded by thermoforming. A molded product is used as a diaphragm.

Function The present invention provides that the surface material (front and back surfaces) of the molded product has a large elastic modulus (6.2X 1010 dyne/-, about 1
・Because it has a three-layer structure consisting of polyimide (3 times) and polyamide-imide, which has a large mechanical internal loss (2.6 times that of polyester film at 0.05) for the core material, It has extremely high bending rigidity, so the diaphragm does not deform during vibration or split resonance occurs, and the core material has a large mechanical internal loss, so there is little fray in frequency characteristics, and excellent sound pressure-frequency characteristics and distortion. It is possible to obtain a speaker with excellent rate and phase characteristics. Since this diaphragm material is made of polyimide as its main component, it can be plastically deformed by heat and pressure, and can be processed into any desired diaphragm shape using, for example, a press. Therefore, not only a flat diaphragm but also a dome-shaped diaphragm can be freely processed, and arbitrary acoustic characteristics can be obtained. Furthermore, since it is a polyimide-based material, it has a very high heat softening temperature, so it has excellent heat resistance, and a speaker with high input resistance characteristics can be obtained.

Example Below, regarding a speaker diaphragm according to an example of the present invention,
This will be explained with reference to the drawings.

FIG. 1 shows a sectional view of a speaker in one embodiment of the present invention. In Fig. 1, numeral 4 is a diaphragm formed by sheetra heat press or the like with a three-layer structure in which polyimide prepreg sheets are bonded to both sides of a polyamide prepreg sheet, 6 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) in a magnetic circuit.

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

As shown in FIG. 1, the speaker consists of a vibration system such as a diaphragm 4, a voice coil bobbin 6, and a voice coil 6, and a magnetic circuit system (not shown) consisting of a magnet, a ball, a plate, and a yoke. Voice coil 6 in a uniform magnetic field
When an audio current flows through the voice coil 6, a vertical electromagnetic force is generated in the voice coil 6, causing it to vibrate in accordance with the current. This vibration is properly transmitted to the vibration of the diaphragm 4 and emitted as a sound wave.

The method for manufacturing the diaphragm 4 will be described below.

First, a 20 μm polyimide prepreg sheet was used as the surface material, and an 80 μm polyamide prepreg sheet was used as the core material. This material was heat-pressed at a temperature of 260°C and a pressure of 50kg/C[II'' for a time of e.
o min (7) Condition tetome shape (dome diameter φ3om
m) to form a diaphragm.

As described above, according to this embodiment, the speaker uses the diaphragm 4 made of a three-layered sheet formed by heat pressing or the like, in which polyimide prepreg sheets are bonded to both sides of a polyamide prepreg sheet. Good acoustic characteristics are obtained without deformation or split resonance, and when compared with an aluminum dome-shaped diaphragm of the same shape, the distortion rate is reduced by 24 dB. Further, the high-frequency resonance frequency increases from 21 KHz to 2 s KHz, and the peak dip of the output sound pressure is also ±3 dB, which is about a ±3 dB decrease compared to an aluminum diaphragm.

Effects of the Invention As described above, the present invention provides 3 sheets in which polyimide prepreg sheets are bonded to both sides of a polyamide prepreg sheet.
This is a diaphragm that uses a molded product in which sheets with a layered structure are laminated and bonded by thermoforming such as heat pressing, and it is possible to obtain a speaker with a low distortion rate, a high high resonance frequency, and a large acoustic output. This makes it possible to realize an excellent speaker with good acoustic characteristics.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a vibration system of a speaker according to an embodiment of the present invention, and FIG. 2 is a sectional view of a vibration system of a conventional speaker. 4...Diaphragm, 6...Voice coil bobbin, 6...Voice coil. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 4 - Movable jaw 5" - Voice coil 6 - One claw 3"

Claims (1)

[Claims] A speaker diaphragm characterized by using a molded product in which a three-layer structure sheet in which a polyimide prepreg sheet is laminated on both sides of a polyamide prepreg sheet is laminated and bonded by thermoforming.