JP3178344U - Electromagnetic acoustic transducer - Google Patents

Abstract

An electromagnetic acoustic transducer capable of further improving sound quality in an audible frequency band is provided.
A pole piece is disposed opposite to a diaphragm, a coil is disposed on the outer periphery of the pole piece, and a magnet is disposed on the outer periphery of the coil. In the electromagnetic acoustic transducer having a band of 20 Hz to 20 kHz, the coil 14 is made of a silver wire or a silver-plated copper wire.
[Selection] Figure 1

Description

  The present invention relates to an electromagnetic acoustic transducer, and more particularly to an electromagnetic acoustic transducer suitable for an earphone.

  The electromagnetic acoustic transducer has a pole piece (iron core) disposed facing the diaphragm, a coil disposed on the outer periphery of the pole piece, and a magnet disposed on the outer periphery of the coil. The coil and the magnet are fixed to the plate. Examples of this type of electromagnetic acoustic transducer include Patent Documents 1 and 2.

  Conventionally, for the purpose of improving sound quality, it is known to change the wiring for supplying current to the coil from a copper wire to a silver wire. An example of such wiring is Patent Document 3.

JP 2002-55683 A JP 2003-125488 A JP-A-11-339568

  In audio, the frequency band that humans can mainly hear is 20 Hz to 20 kHz. In this audible frequency band, how to improve the sound quality has been a problem. There is a limit to the improvement of sound quality depending on the above-mentioned conventional technology.

  An object of the present invention is to provide an electromagnetic acoustic transducer capable of further improving sound quality in an audible frequency band.

  According to claim 1 of the present invention for solving the above-mentioned problems, a pole piece is disposed facing the diaphragm, a coil is disposed on the outer periphery of the pole piece, and a magnet is disposed on the outer periphery of the coil. In the electromagnetic acoustic transducer in which the frequency band of the diaphragm is 20 Hz to 20 kHz, the coil is made of a silver wire or a silver-plated copper wire.

  The difference between the maximum and minimum of Q (current) at resonance in the frequency band of 1 kHz to 10 kHz between the electromagnetic acoustic transducer using a copper wire coil and the electromagnetic acoustic transducer using a silver wire coil There is. This seems to affect the sound quality. The difference in the electrical equivalent circuit is only the material of the coil, and the silver wire has the phenomenon that the phenomenon occurs at the time of resonance because the direct current resistance is smaller than that of the copper wire.

It is sectional drawing of the earphone to which one Embodiment of the electromagnetic type acoustic transducer of this invention is applied. It is explanatory drawing of the part which supplies an electric current to a coil. It is a figure which shows the frequency characteristic in a copper wire coil and a silver wire coil. It is a related figure of the frequency and synthetic resistance in a copper wire coil and a silver wire coil. It is the same relationship diagram as FIG. It is a related figure of the frequency of an electromagnetic type acoustic transducer in a copper wire coil and a silver wire coil, and synthetic resistance difference.

  An embodiment of an earphone to which the electromagnetic acoustic transducer of the present invention is applied will be described with reference to FIGS. The case 1 includes a cylindrical earplug mounting portion 1a for attaching the earplug 2 on one side, and an electromagnetic acoustic transducer 10 which will be described later on the other side of the earplug mounting portion 1a with a diameter larger than that of the earplug mounting portion 1a. And a cylindrical converter housing 1b. The earplug mounting portion 1a and the transducer housing portion 1b are in communication with each other, and the end portions of the earplug mounting portion 1a and the transducer housing portion 1b are open.

  An earplug 2 is attached to the outside of the earplug mounting portion 1a. The earplug 2 has a cylindrical attachment portion 2a that is elastically attached to the earplug attachment portion 1a, and has elasticity by extending in an arc shape from the tip of the attachment portion 2a toward the transducer housing portion 1b. The ear insertion portion 2b is inserted into the ear. Two earwax filters 3, 3 are disposed in the earplug mounting portion 1 a via spacers 4, and the earwax filters 3, 3 are fixed by an earwax filter fixing ring 5.

  The electromagnetic acoustic transducer 10 housed in the transducer housing portion 1b has the following configuration. A diaphragm 11 is placed on the bottom of the converter housing 1b, and a magnetic piece 12 made of a magnetic material is fixed to the earplug mounting portion 1a side of the diaphragm 11. A pole piece 13 made of a magnetic material is disposed corresponding to the center of the diaphragm 11 with a certain gap, and a cylindrical coil 14 is disposed on the outer periphery of the pole piece 13. ing. Further, a cylindrical magnet 15 is disposed on the outer periphery of the coil 14 with a slight gap, and the coil 14 and the magnet 15 are fixed to a plate 16 fixed to the pole piece 13. The magnet 15 and the diaphragm 11 are held by a holding ring 17 attached to the converter housing 1b, and a hook 18 is provided in the converter housing 1b so as to hold the holding ring 17 in the converter housing 1b. The hook 18 is held by the engaging portion 1c of the converter housing portion 1b.

  Wires 21 and 21 of an AC power source 20 are connected to the coil 14. Therefore, when a current is supplied to the coil 14, the magnetic flux generated in the coil 14 changes the magnetic flux of the closed magnetic circuit, and the attractive force generated in the magnetic piece 12 to which the diaphragm 11 is fixed is changed. Generate sound.

  The present embodiment is characterized in that, in an electromagnetic acoustic transducer that generates sound in a human audible frequency band (20 Hz to 20 kHz), the coil 14 conventionally using a copper wire is formed of a silver wire. . The applicant of the present application has judged that the material of the coil 14 may affect the sound quality, and repeated trial experiments, and as a result of having several people familiar with the difference in frequency characteristics and sound, the silver wire coil has a good sound quality. It turns out that it can be obtained. Therefore, the applicant of the present application conducted a comparative experiment between a conventional copper wire coil and a silver wire coil based on the fact that the electromagnetic acoustic transducer of the silver wire coil can obtain good sound quality.

  First, frequency characteristics were investigated in both an electromagnetic acoustic transducer using a copper wire as the coil 14 and an electromagnetic acoustic transducer using a silver wire. As a result, the relationship shown in FIG. 3 was obtained. As is apparent from FIG. 3, there was almost no difference between the two at a frequency of 1 kHz or less. There is a portion where the magnitude of the sound pressure shows a difference of a little less than about 2 dB at a frequency of 1 kHz or more, but 2 dB is a difference of about 1.259 times when converted into a general magnification, and is generally 3 dB. (Approximately 1.413 times) The following sensitivity difference cannot be judged. That is, the difference that cannot be distinguished in the frequency characteristics is shown.

  FIG. 4 shows the result of measuring the difference in the combined resistance of the coil 14 shown in FIG. As can be seen from FIG. 4, the combined resistance of the coil prepared for the experiment is slightly larger in the silver wire coil than in the copper wire coil. Here, the combined resistance Z can be expressed by Z = ωL. ω is 2π × f, where π is the pi, f is the frequency, and L is the inductance of the coil 14.

  Next, in the earphone shown in FIG. 1, the result of measuring the combined resistance of a product using copper wire and silver wire with different materials for the coil 14 is shown in FIG. Here, the combined resistance indicates a resistance obtained as a result of combining an electric system, a mechanical system, and an acoustic system. FIG. 6 is a graph showing how much the difference between the copper wire and the silver wire is generated with respect to the copper wire in order to make the difference between them easier to see. As apparent from FIG. 6, the difference in the combined resistance occurs in the vicinity of about 1 kHz to 10 kHz, and the other frequencies show almost the same difference (less than about 5%). In the frequency band causing the difference, resonance and anti-resonance generated by the electrical system, the mechanical system, and the acoustic system are generated. The difference in the positive direction is greatly increased at the time of resonance, and the difference in the negative direction is generated at the time of anti-resonance due to the difference in Q at the time of resonance on the electrical equivalent circuit made by the electrical system, mechanical system, and acoustic system. It is a phenomenon. In other words, the resistance of the DC resistance component is smaller for the silver wire. Thus, there is a difference of 25% at the maximum and minimum due to the difference in the combined resistance at the time of resonance in the frequency band of 1 kHz to 10 kHz. This seems to affect the sound quality. The difference in the electrical equivalent circuit is only the material of the coil 14, and the silver wire generates the phenomenon at resonance because the DC resistance is smaller than that of the copper wire. Thus, it is clear that the finished product shown in FIG. 1 is different from the comparison of the single coil 14 shown in FIG.

  In addition, although the said embodiment demonstrated the case where a silver wire was used for the coil 14, the sound quality better than the case where only a copper wire is obtained also in the silver plating copper wire which gave silver plating to the copper wire is obtained.

1 Case 2 Earplug 10 Electromagnetic acoustic transducer 11 Diaphragm 12 Magnetic piece 13 Pole piece 14 Coil 15 Magnet 16 Plate

Claims (1)

  A pole piece is disposed facing the diaphragm, a coil is disposed on the outer periphery of the pole piece, a magnet is disposed on the outer periphery of the coil, and the frequency band of the diaphragm is 20 Hz to 20 kHz. The electromagnetic transducer according to claim 1, wherein the coil is made of a silver wire or a silver-plated copper wire.