JPS6150439B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to the improvement of a transducer that converts the mechanical energy of vibrations of air, liquid, records, etc. into electrical energy, and improves the response, sensitivity, linearity, and dynamic range of the conversion. The purpose is to obtain an excellent transducer such as Conventional technology Conventionally, as transducers that convert mechanical energy of vibration into electrical energy, there are moving coil type pickups that generate electromagnetic induced electromotive force by vibrating an electromagnetic coil in a magnetic field, and moving coil type pickups that generate electromagnetic induced electromotive force by vibrating an electromagnetic coil in a magnetic field. Moving magnet type pickups, which generate electromagnetic induced electromotive force by vibrating a magnet, are used for records. In addition, a method to obtain electrostatically induced electromotive force by vibrating an electret film near an electrode is used for microphones, and for speakers, an audio signal current is passed through an electromagnetic coil near a permanent magnet to cause the electromagnetic coil to vibrate. A method in which an audio signal voltage is applied to an electrode to cause a nearby plastic film to vibrate using electrostatic force has been put into practical use. Problems to be Solved by the Invention However, in all cases, excellent responsiveness, output, and efficiency have not been achieved. In other words, moving coil type pickups have relatively good response, but their output is extremely low, so they require dedicated expensive transformers and low-noise amplifiers.
Moving magnet pickups have high output, but because they vibrate a heavy permanent magnet, they have poor response and are not good at faithfully reproducing high-pitched sounds. Further, since the electret type microphone has a thin and light film vibrator, the response is extremely good, but since it uses an electrostatic induction method, the output is very small and the S/N ratio is low compared to the electromagnetic induction method. As a speaker,
The method of vibrating an electromagnetic coil has high efficiency and a high sound pressure level, but the response is poor and high-pitched sounds cannot be produced.
The method of vibrating a plastic film using electrostatic induction force has a good response because the vibrating body is extremely thin and lightweight, and the sound quality of high-pitched sounds is good, but the problem is that the efficiency is extremely low and the sound pressure level is low. The present invention aims to eliminate the above-mentioned drawbacks and provide a transducer that is excellent in both responsiveness and output/efficiency, and will be described in detail below with specific examples. Means for Solving the Problems The transducer of the present invention forms a perpendicularly magnetized ferromagnetic layer on a base material such as a molded polymer, a non-magnetic metal, or an inorganic material, and places it in close proximity to an electromagnetic coil. It was established. Effect In the above configuration, when the base material is mechanically vibrated,
A magnetic field change occurs and an electrical signal is generated between the terminals of an electromagnetic coil placed near the substrate. Conversely, when an electric signal is supplied between the terminals of the electromagnetic coil, a change in the magnetic field occurs, causing the base material to mechanically vibrate and generate sounds and the like. Example FIG. 1 shows an embodiment of the transducer of the present invention. In Fig. 1, 1 is a polymer molded product;
A base material such as a non-magnetic metal or an inorganic material, 2 is a perpendicularly magnetized ferromagnetic layer formed on this base material 1, and the base material 1 and the perpendicularly magnetized ferromagnetic layer 2 form a vibrating body. There is. 3 and 4 are ring-shaped electromagnetic coils installed close to the front and back sides of the vibrating body, respectively, A and B are terminals of the coil 3, and C and D are terminals of the coil 4. The ferromagnetic layer 2 is made of a material that is magnetized almost perpendicularly to the plane of the magnetic layer against a demagnetizing field, and is magnetized in one direction perpendicular to the plane as shown in the figure, with one side having an N magnetic pole and the other side. Specifically, an alloy such as Gd-Co, Tb-Fe, Co-Cr, etc. is formed on the base material 1 by a method such as a sputtering method or a vacuum evaporation method, and then magnetized. obtained by doing.
In FIG. 1, the transducer vibrates the base material 1 with mechanical vibrations such as acoustic air vibrations, and vibrates the magnetic double layer of the vertical magnetic layer 2 in the vicinity of the electromagnetic coils 3 and 4. Electric signals are induced between terminals A and B and between terminals C and D of the coil 4, thereby functioning as a microphone. Also,
Although not shown, if the mechanical vibration from the record stylus is transmitted by a cantilever and one end of the cantilever and the base material 1 are bonded, it will function as a record pickup. Conversely, by supplying electrical signals between terminals A and B and between terminals C and D, magnetic field changes are created, and the vertical magnetic layer 2, and thus the base material 1, are mechanically vibrated by magnetic force, and audio, etc. generate. That is, as an example, a base material 1 with a thickness of 10 microns
If we consider that a thin film of Co, Cr alloy with a thickness of 0.2 microns is formed on a polyimide film to form the perpendicular magnetic layer 2, and magnetized in one direction perpendicular to the film surface, this is approximately 600 cm ² at 1 g. , and the residual magnetic flux density is about 3000 Gauss, so the surface magnetic flux per unit weight is extremely weak. By the way, when compared to extremely strong samarium-cobalt permanent magnets, the specific gravity of samarium-cobalt is about 8.0 and the residual magnetic flux density is about 9000 Gauss.If the magnetic pole area per gram is 1 cm ² , the surface magnetic flux per unit weight is There are about 200 times more perpendicular magnetic layers 2 than samarium-cobalt permanent magnets. Therefore, if this perpendicular magnetic layer 2 is used as a vibrator, it is thin and extremely lightweight, and has a large surface magnetic flux, so if the electromagnetic coils 3 and 4 are placed close to it, it can be used to suppress slight air vibrations and mechanical vibrations. It responds sensitively to energy and has a large electromagnetic induction effect, so it can be converted into electrical energy with high efficiency. Conversely, when a signal current is passed through the electromagnetic coils 3 and 4, the vertical magnetic layer 2 vibrates sensitively, causing the air to become extremely Since it can vibrate efficiently and with high responsiveness, it is possible to achieve both responsiveness, output, and efficiency at an unprecedentedly high level. It is also possible to function as a speaker or the like. For example, base material 1 has a thickness of 10
A film made of polyester, aromatic nylon, Ti, B, Be, mica, carbon, etc. with a thickness of about 0.5 microns or less is used, and a perpendicularly magnetizable ferromagnetic layer 2 is formed thereon as a thin film with a thickness of about 0.5 microns or less. Because it is extremely lightweight and has a large amount of surface magnetic flux, it has high energy conversion efficiency between mechanical vibration and electrical signals, and has excellent responsiveness. Next, a specific example of this embodiment will be explained. (Example 1) Co on a polyimide film with a thickness of 10 microns
- Cr alloy (Co: 80% by weight, Cr: 20% by weight) was formed as a thin film with a thickness of 0.5 microns using the sputtering method. The residual magnetic flux density was 3000 Gauss. this
A 100mmφ circular cutout was used to fabricate a prototype speaker with the configuration shown in Figure 1. As shown in Table 1, the sound pressure level of this speaker is 1k compared to Comparative Example 1, a commercially available cone-type speaker for medium and high frequencies (6 to 12 cm in diameter).
The sound pressure level at Hz is similar, and the sound pressure level at 20kHz is significantly higher. In Comparative Example 2, a 10 micron thick polyvinylidene fluoride film was made into an electret, cut out into a 100 mm diameter circle, and electrodes were placed on both sides to make a speaker.
This had good response, but had low efficiency in reproducing high frequencies, and compared to Example 1, only considerably smaller outputs at 1 kHz and 20 kHz could be obtained.

[Table] (Specific example 2) Polyimide film Gd-Co with a thickness of 5 microns
(50:50) A thin film of 0.5 micron thickness was formed on both sides using the sputtering method, a cantilever was connected, and an electromagnetic coil was placed nearby to create a prototype record pickup. As shown in Table 2, the compliance (mechanical response) was significantly higher than that of the commercially available moving magnet type pickup of Comparative Example 3, and records could be played up to about 55 kHz. Furthermore, the output is significantly higher than that of the commercially available moving coil type pickup of Comparative Example 4. Therefore, in this case as well, both responsiveness and output are achieved at a high level. For the measurements in Table 2, a 1kHz reference signal of the test record (CBS STR-150) was used.

[Table] Next, another embodiment of the transducer of the present invention will be described with reference to FIG. 2. 5 is a base material made of electret, which is charged with different polarities on the front and back sides to form an electric double layer;
is a perpendicularly magnetized ferromagnetic layer formed on the base material 5. The base material 5 and the ferromagnetic layer 6 form a vibrating body. The electret used is one semipermanently charged to about 500 to 900 V by forcibly charging (poling) a material such as polypropylene, polycarbonate, polyvinylidene fluoride, or the like. 7 and 8 are ring-shaped electromagnetic coils installed close to each other on the front and back sides of the vibrating body, A and B are terminals of the coil 7, and C and D are terminals of the coil 8. Second
When the configuration shown in the figure is used, the conversion between electromagnetic energy and mechanical energy is performed more efficiently. That is, the vibration of the magnetic double layer of the ferromagnetic layer 6 generates an electromotive force due to electromagnetic induction between terminals A and B and between terminals C and D, and at the same time, the vibration of the electret of the base material 5 causes the entire coil 7 and the coil to 8, an electrostatically induced electromotive force is generated. So coil 7
By connecting 8 and 8 in series or by connecting them with phase adjustment using a capacitor or the like, it becomes possible to receive energy from both electromagnetic induction and electrostatic induction, and higher conversion efficiency can be obtained. In this case, as shown in FIG. 3, the electromagnetic coils 7 and 8 may be those in which a thin film-like conductor 10 is formed on a base material 9 such as a polymer film, or those in which these are stacked in multiple layers. If such a material is used, a highly sensitive and highly efficient transducer can be obtained because of good electrostatic coupling with the base material 5 shown in FIG. The vibrating body may be one in which perpendicularly magnetized ferromagnetic layers are provided on both sides of the base material, or conversely, the base material 5 is provided on both sides of a perpendicularly magnetized ferromagnetic material layer, or a vibrating body may be one in which a perpendicularly magnetized ferromagnetic material layer is provided on both sides of the base material. Of course, it is also possible to use a layered one. Next, a specific example of the embodiment shown in FIG. 2 will be described. (Specific Example 3) Co-Cr (Cr: 20% by weight) was vacuum-deposited on a polyvinylidene fluoride film with a thickness of 5 microns,
A perpendicularly magnetized thin film with a thickness of 0.2 microns was formed, the film was polled, and it was made into an electret with a charging voltage of 850V. The residual magnetization of the perpendicular magnetic ferromagnetic layer 6 was 2800 Gauss. Next, we used this as a 10mmφ vibrator to fabricate a prototype microphone with the structure shown in Figure 2. However, as the electromagnetic coils 7 and 8, five layers of the structure shown in FIG. 3 were used. (Concrete Example 4) The same structure as in Concrete Example 3 was used, but the film was not polled, that is, only electromagnetic induction by a perpendicularly magnetized film was used. (Comparative Example 5) The same material as in Example 3 was used, but without the Co--Cr thin film, that is, using only electrostatic induction by electrets.

[Table] Table 3 shows the results of these experiments. Compared to the electrostatic induction method of Comparative Example 5, the electromagnetic induction method using the perpendicular magnetic layer of Example 4 had significantly higher microphone sensitivity, and the combined method of Example 3 had even higher sensitivity. This tendency did not change even at high frequencies. Effects of the Invention As described above, the transducer of the present invention includes a perpendicularly magnetized ferromagnetic layer formed on a base material such as a polymer molded product, a nonmagnetic gold layer, an inorganic material, etc., and an electromagnetic Because it is equipped with a coil, it is possible to obtain a vibrating body that is thin, lightweight, and has a high surface magnetic flux (significantly high surface magnetic flux per unit weight), which achieves unprecedented levels of responsiveness, efficiency, and sensitivity. It is highly practical when applied to speakers, microphones, record pickups, etc.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a main part of a transducer showing a first embodiment of the present invention, FIG. 2 is a cross-sectional view of a main part of a transducer showing a second embodiment of the present invention, and FIG. It is a perspective view of the electromagnetic coil of the same transducer. 1, 5... Base material, 2, 6... Perpendicular magnetization ferromagnetic layer, 3, 4, 7, 8... Coil.

Claims (1)

[Claims] 1. A transducer characterized in that a perpendicularly magnetizable ferromagnetic layer is formed on a base material such as a molded polymer, a nonmagnetic metal, an inorganic material, etc., and is provided in close proximity to an electromagnetic coil. . 2. The transducer according to claim 1, wherein the base material is an electret.