JP3005099B2 - Electroacoustic transducer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electro-acoustic device such as a loudspeaker which improves the adhesiveness between a diaphragm and a voice coil bobbin and which can be used in a bad environment where the diaphragm is deteriorated. Related to a converter.

[0002]

2. Description of the Related Art Among electroacoustic transducers, a speaker is generally used as an audio device for reproducing an audio signal. For example, a speaker is installed in a fuel tank of an automobile to measure a fuel capacity in the tank. May be used as a sensor.

[0003]

In this case, since the fuel sensor is directly exposed to fuel such as gasoline due to its role, the main components of the electro-acoustic transducer such as the diaphragm and the adhesive used for assembling are used. Requires fuel resistance (herein referred to as gasohol resistance).

[0004] For this reason, as a diaphragm material, for example, PPS (P
Although it is preferable to use polyphenylene sulfate, it is necessary to improve the adhesiveness of this PPS because it is a hardly adherent body. On the other hand, there has been a problem that it is necessary to use an adhesive which is not affected by fuel and has a strong adhesive force with PPS at the same time.

[0005]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above. It is an object of the present invention to provide a diaphragm having excellent gasohol resistance and to securely bond the diaphragm to a voice coil bobbin. In particular, an object of the present invention is to provide an electroacoustic transducer suitable for use as a fuel measurement sensor.

[0006]

According to the present invention, the vibration plate 6 is made of a material having gasohol resistance, the surface of the vibration plate 6 is subjected to plasma treatment, and tricyclodecane dimethanol diacrylate is used as a main component. The above object is achieved by a configuration in which the voice coil bobbin 7 having the voice coil 8 is adhered to the diaphragm 6 with the adhesive 9 as described above.

[0007]

In the present invention, a diaphragm made of PPS having sufficient gasohol resistance is used, and an adhesive mainly composed of tricyclodecane dimethanol diacrylate is used as an adhesive. Then, in order to improve the adhesive strength, the surface of the diaphragm made of a PPS film material is subjected to plasma processing. By performing this processing,
The surface is chemically and physically modified to improve the adhesiveness.

[0008]

FIG. 1 shows an embodiment of an electroacoustic transducer according to the present invention. In the figure, reference numeral 1 denotes a cylindrical case having a bottom. A magnetic circuit component 2 is accommodated in the case 1.
The magnetic circuit component 2 includes a yoke 3 having an inverted T-shaped cross section having a center pole 3a, a ring-shaped magnet 4 provided on a flange portion of the yoke 3, and an upper portion of the magnet 4 provided therein. The peripheral surface is formed of a ring-shaped plate 5 which is opposed to the upper peripheral surface of the center pole 3a so as to form a magnetic gap.

A diaphragm 6 formed by forming a PPS film material into a predetermined shape is provided on an upper portion of the case 1. Prior to assembling, the surface of the vibration plate 6 is subjected to a plasma treatment to modify the surface and improve the adhesive force of the adhesive 9. Normally, the cylindrical voice coil bobbin 7 having the voice coil 8 is bonded to the center of the rear surface of the diaphragm 6 with an adhesive 9.
It may be performed on the bonding area on the back surface or on the entire back surface, but the front surface may also be subjected to plasma treatment. Although PPS is used as the material of the diaphragm 6 in the above description, it is also possible to use a diaphragm made of another gasohol-resistant material after performing a plasma treatment.

In order to check the modified state of the surface of the diaphragm 6, a chemical analysis using an electron spectrometer (Electron) is performed.
Spectroscopy for Chemical
(Analysis), the surface analysis is as shown in FIG. In the figure, a is an untreated one, b is a plasma treated surface of the diaphragm 6 for 7 seconds, c
Is a characteristic when post-processing is performed for 60 seconds, and d is a characteristic when post-processing is performed for 300 seconds.

In this analysis, photoelectrons generated by applying X-rays to the surface of a PPS sample piece are divided into energies, and the change in the number of photoelectrons with respect to kinetic energy is observed as a spectrum. Then, from the obtained data, the number of photoelectrons with respect to the kinetic energy becomes a spectrum, and the qualitativeness of the element on the surface of the sample piece can be grasped from the peak position. Analysis results of O (oxygen), C (carbon), and S (sulfur)
Represents an element corresponding to the peak position.

This plasma treatment causes an increase in O (oxygen) and a decrease in S (sulfur), and the surface of the diaphragm 6 made of a PPS film material is clearly modified. However, in the treatment d, since S (sulfur) and C (carbon) are extremely reduced, it is understood that the composition of PPS is considerably destroyed, and the adhesiveness is conversely reduced. It is preferable that the plasma processing time is about several seconds to several minutes.

Thus, the voice coil bobbin 7 is adhered to the diaphragm 6 using the adhesive 9, and the voice coil 8 of the voice coil bobbin 7 is arranged in the magnetic gap. A cover 10 having a sound hole 10a in the case 1
Is covered. In this case, the outer peripheral portion of the diaphragm 6 is the case 1
And the cover 10. Note that the cover 10 and the case 1 are integrated by an appropriate means such as a screw or an adhesive 9 or another adhesive.

In the present invention, the adhesive 9 includes:
A material containing tricyclodecane dimethanol diacrylate, which has good gasohol resistance and good adhesion to PPS, is used. Examples 1 to 2 of adhesives containing tricyclodecane dimethanol diacrylate as a main component
Is shown. The above-mentioned materials were stirred and mixed to prepare Examples 1 and 2. Curing is at 130 ° C. for 10 minutes.

FIG. 3 shows a case where the vibration plate 6 is subjected to a plasma treatment and the voice coil bobbin 7 is adhered via an adhesive 9, and a surface treatment is carried out for one minute by corona discharge or sandblasting without using the plasma treatment. The adhesive strength before and after the fuel resistance test is shown. As shown in FIG. 4, the adhesive strength is such that the voice coil bobbin 7 and the diaphragm 6 are adhered to each other with an adhesive 9 and the diaphragm 6 is pulled at a tension rate of 40 mm / min as indicated by an arrow. 6 and the voice coil bobbin 7. Before the fuel resistance test, each of the treatments has substantially the same tensile strength.However, after the fuel resistance test immersed in the fuel for a predetermined time, the tensile strength is not reduced in the case of the present invention. The treatment reduced the tensile strength.

[0016]

As described above, in the electro-acoustic transducer of the present invention, the diaphragm 6 is made of a material having gasohol resistance, and the surface of the diaphragm 6 is subjected to plasma treatment and tricyclodecanedimethanol is used. Since the voice coil bobbin 7 having the voice coil 8 was bonded to the diaphragm 6 with an adhesive 9 containing diacrylate as a main component,
Even when used as a fuel measurement sensor, the diaphragm 6 has excellent adhesion to the voice coil bobbin 7 and has sufficient gasohol resistance, so that it can be used without any problem.
There is such an effect. In the above-described embodiment, the description has been made on the assumption that the sensor for fuel measurement is used. However, the sensor can be used as a normal speaker in a factory or the like where gas or the like adversely affects the diaphragm or the like. It goes without saying that a microphone may be used as the instrument.

[Brief description of the drawings]

FIG. 1 is a sectional view of one embodiment of the present invention.

FIG. 2 is an explanatory diagram of measurement results of chemical analysis by an electron spectrometer when a plasma treatment is performed on a diaphragm.

FIG. 3 is an explanatory diagram showing a state of tensile strength between a diaphragm and a voice coil bobbin before and after a fuel resistance test in each process.

FIG. 4 is an explanatory diagram showing a test method of a diaphragm, a voice coil bobbin, and a tensile strength.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Case 2 Magnetic circuit component 3 Yoke 3a Center pole 4 Magnet 5 Plate 7 Voice coil bobbin 8 Voice coil 9 Adhesive 10 Cover 10a Sound hole

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Akira Hara 512, Miyazawacho, Akishima-shi, Tokyo Foster Electric Co., Ltd. (56) References JP-A-60-210096 (JP, A) JP-A-61-161099 (JP, A) JP-A-56-55417 (JP, A) JP-A-4-85898 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04R 9/04 105 G01F 23 / 22 H04R 7/02 H04R 31/00

Claims (1)

(57) [Claims] The vibration plate 6 is made of a material having gasohol resistance, and the surface of the vibration plate 6 is subjected to plasma processing.
An electroacoustic transducer characterized in that a voice coil bobbin 7 having a voice coil 8 is bonded to the diaphragm 6 with an adhesive 9 containing tricyclodecane dimethanol diacrylate as a main component.