JP6288668B2 - Condenser headphones - Google Patents

Description

  The present invention relates to a condenser headphone, and more particularly to a condenser headphone provided with a protective film on at least one surface facing a user's ear in a headphone unit housed in a headphone housing.

  The capacitor headphone unit generally employs a push-pull drive type in which fixed poles are arranged on both sides of the diaphragm in order to reduce reproduction distortion. In this type of condenser headphone unit, a signal voltage for audio reproduction is applied to each fixed pole in a state where a polarization voltage of several hundred volts is applied to the diaphragm. A sound wave is generated by the vibration of the diaphragm. Then, the sound wave generated along with the vibration of the diaphragm passes through a plurality of openings (through holes) formed in the fixed pole and reaches the ear of the user wearing the capacitor headphones.

Therefore, in the above-described push-pull drive type capacitor headphones, one fixed pole is always located on the user's ear side.
For example, when outputting a sound pressure of 100 dB, an audio signal voltage of about 100 V (rms) is applied to the fixed pole. Therefore, dielectric breakdown may occur, and a problem may occur that the voltage applied to the fixed electrode gives an electric shock (electric shock) to the user.

  Further, in this type of condenser headphone, the surface resistance of the constituent members of the headphone tends to decrease due to the influence of perspiration from the human body. Therefore, creeping discharge is likely to occur, increasing the risk of electric shock due to discharge and the possibility of damage to the diaphragm due to electric shock.

In order to prevent electric shock due to such discharge, it is conceivable to design the headphone unit so that the distance between the headphone unit and the human ear is large. However, according to such a design, a decrease in output sound pressure as headphones is inevitable.
Further, in the prior art, in order to prevent the unit from deteriorating due to sweating of the human body, it has been proposed to insert a moisture-proof film made of a plastic film between the fixed electrode and the ear. However, since the moisture-proof film has only a thickness of about 1 to 2 μm, electric shock due to discharge cannot be prevented.

In order to deal with the problem of the above-described capacitor headphones, the present applicant has previously proposed a capacitor headphone using a double-sided printed circuit board as a fixed pole disposed on both sides of the diaphragm, which is disclosed in Patent Literature. 1 is disclosed.
According to the previously proposed capacitor headphones, a signal voltage for sound reproduction is applied to each inner conductive foil facing the diaphragm located at the center in the double-sided printed circuit board constituting the fixed pole. The conductive foil on the outer side of the double-sided printed circuit board constituting the fixed pole arranged on the user's ear side is configured to be connected (grounded) to a reference potential point.

  According to the capacitor headphones disclosed in Patent Document 1 described above, since the outer conductive foil facing the user's ear is grounded, the user's electric shock can be effectively prevented. In addition, it is possible to provide low-cost condenser headphones that take advantage of the structural characteristics of the double-sided printed circuit board.

JP 2006-270663 A

By the way, the capacitor headphone disclosed in Patent Document 1 uses a printed circuit board as a fixed pole. This fixed pole has a problem that its mass is small and its mechanical strength (rigidity) is inferior.
For this reason, the printed circuit board as a fixed pole tends to vibrate by the reaction force of the diaphragm. This vibration of the fixed pole hinders high-quality reproduction of the sound wave. Moreover, the flatness of the surface of the printed circuit board is essentially low. For this reason, in order to avoid contact with the diaphragm, it is necessary to design a larger distance between them. Therefore, there is a limit to increasing the sound pressure sensitivity as a condenser headphone.

Therefore, by using a metal material for the fixed pole, it is possible to eliminate the cause of the above-mentioned problem that the reproduction with high sound quality is impossible and the point where the sound pressure sensitivity is limited.
However, when a metal material is used for the fixed pole, the metal material is an electrical conductor, and thus it is impossible to directly adopt the configuration related to the measures for preventing electric shock of the user disclosed in Patent Document 1.

  Therefore, the present invention aims to improve the sound quality by using a metal material for the fixed electrode, and to effectively function as a measure for preventing the electric shock of the user or the measure for preventing the electret in the electret type condenser headphones. It is an object to provide a condenser headphone that can be used.

The condenser headphone according to the present invention made to solve the above-described problems uses a condenser headphone unit including a diaphragm and fixed poles each having a plurality of through holes on both sides of the diaphragm. Each fixed pole is formed of a metal material, and a protective film is disposed so as to cover the fixed pole located on the user's ear side, and the fixed pole located on the side opposite to the user's ear side is provided. A second protective film is disposed so as to cover the conductive film, and a conductive film is formed on the surface of the protective film facing the user's ear, and the conductive film is electrically grounded . The conductive film formed on the protective film is not electrically grounded, and the protective film and the second protective film are each provided with irregular wrinkles over the entire surface .

In this case, in a preferred embodiment, a metal film is formed on the diaphragm, and a polarization voltage is applied to the metal film. In addition, a configuration is adopted in which signal voltages having opposite phases to each other are applied to the fixed poles.
In another preferred embodiment, electret materials each made of a polymer film are disposed on the surface of each fixed pole facing the diaphragm. In addition, a configuration is adopted in which signal voltages having opposite phases to each other are applied to the fixed poles.

In any form using the above-described polarization voltage or using the electret material, the protective film covering the fixed electrode located on the user's ear side is preferably supported by the support member at the periphery. In addition, the configuration mounted on fixed pole disposed on the ear side of the front SL using support member user is employed.

Further, a second protective film will covering a fixed pole that is located on the opposite side to the ear side of the user, with its peripheral edge portion is supported by the support member, the ear-side of the user by using the supporting member The structure attached to the fixed pole located on the opposite side to is adopted.

  According to the condenser headphone according to the present invention, the fixed pole formed of a metal material having a plurality of through holes on both sides of the diaphragm is provided. And a protective film is arrange | positioned so that the fixed pole located in a user's ear | edge side may be covered. A conductive film is formed on the surface of the protective film facing the user's ear. And the structure by which this electrically conductive film was electrically grounded is employ | adopted.

Therefore, since the fixed pole made of a metal material is used, the mechanical strength (rigidity) as the fixed pole can be increased. Thereby, since a fixed pole does not carry out unnecessary vibration, it can contribute to sound quality improvement.
The conductive film formed on the surface of the protective film facing the ear side is electrically grounded. As a result, it is possible to effectively eliminate the above-described problem of electric shock to the user.

  Furthermore, in the condenser headphones using the electret material, the conductive film formed on the protective film can serve as an electrostatic shield. As a result, it is possible to effectively prevent the electret material of the headphone unit from being deteriorated by receiving the electric charge charged on the human body.

It is the front view of the fixed pole which looked at the capacitor headphone unit from one side. It is a center sectional view in the state where a capacitor headphone unit provided with a protective film was disassembled. It is the connection diagram which showed an example of the circuit structure which drives a capacitor | condenser headphone unit. It is sectional drawing which shows the whole structure of the capacitor | condenser headphones which accommodated the capacitor | condenser headphone unit in the headphone housing.

  Hereinafter, a condenser headphone according to the present invention will be described based on an embodiment shown in the drawings. Note that, in each drawing described below, the same part or a part that performs the same function is indicated by the same reference numeral, but in some drawings, a representative part is assigned a reference numeral for detailed explanation due to space limitations. The configuration may be described with reference to reference numerals attached to other drawings.

  1 and 2 show a push-pull drive type capacitor headphone unit 1 provided with fixed poles on both sides of the diaphragm with the diaphragm interposed therebetween. FIG. 1 shows the headphone unit 1 viewed from one side. 2 is a front view of the fixed pole, and FIG. 2 is a central cross-sectional view of a state in which the headphone unit is disassembled by adding a protective film.

For the diaphragm 11, for example, a synthetic resin film such as PET (polyethylene terephthalate) or PPS (polyphenylene sulfide) is used. For example, a metal film such as gold (Au) is formed on one surface of the synthetic resin film (not shown).
The diaphragm 11 is held between a pair of support rings 12 and 12 formed in a ring shape from a metal material in a state where a predetermined tension is applied.

A pair of fixed poles 13 and 13 are arranged on the front and rear with the diaphragm 11 in between. That is, each fixed pole 13 and 13 is each formed in disk shape, for example with metal materials, such as aluminum. As shown in FIG. 1, each of the fixed poles 13, 13 has a plurality of through holes 13 a formed over the entire surface. Further, as shown in FIG. 2, each of the fixed poles 13 and 13 is supported by a pair of insulating seats 14 and 14 whose peripheral edges are formed in a ring shape.
In this case, the fixed pole 13 is fixed to the insulating seat 14 at the peripheral edge using an adhesive as necessary.

In addition, ring-shaped recesses 14a are formed at positions where the insulating seats 14 and 14 face each other. A pair of support rings 12 and 12 holding the diaphragm 11 are attached to the recesses 14a and 14a.
And the protective film 16 attached to the ring-shaped support member 17 is attached to the outer side of each fixed pole 13 and 13 mentioned above. Thereby, the capacitor headphone unit 1 is formed to have a cross-sectional structure shown in FIG.

In the capacitor headphone unit 1, a conductive film 16 a is formed on the protective film 16 disposed on the front side which is the user's ear side, as shown partially enlarged in FIG. 3. . The conductive film 16a is electrically grounded as will be described later.
Further, the above-described conductive film 16a is not necessarily required for the second protective film 16 that covers the fixed electrode 13 located on the side opposite to the ear side of the user. As will be described later, the second protective film 16 functions as a moisture-proof film or a dust-proof film for the capacitor headphone unit 1.

The protective film 16 disposed on both outer sides of the capacitor headphone unit 1 is preferably made of PPS as its material. The protective film 16 made of PPS is given irregular wrinkles over the entire surface as illustrated in an enlarged manner in FIG.
That is, by applying irregular wrinkles to the protective film 16, it is possible to prevent specific natural resonance from occurring in the protective film 16. As a result, it is possible to eliminate deterioration in sound quality caused by the natural resonance of the protective film 16.

  The protective film 16 also has a function as a moisture-proof film that prevents an increase in humidity inside the headphone unit 1. When moisture from sweating from the human body, raindrops, or the like enters the headphone unit 1, dew will form inside. This condensation reduces the surface resistivity of the insulation seat of the headphone unit. The protective film 16 also has an effect of preventing moisture from the outside of the headphone unit 1 from flowing into the headphone unit 1.

  The conductive film 16a formed on the protective film 16 on the user's ear side is preferably formed by vapor deposition means using gold (Au). The gold material has good ductility and has a characteristic that microcracks are hardly generated in the conductive film 16a even if the protective film 16 is irregularly wrinkled as described above.

FIG. 3 shows an example of a drive circuit connected to the capacitor headphone unit 1 described above. This drive circuit includes an input transformer 21 and a DC power source 22 for generating a polarization voltage.
The primary winding 21 a of the input transformer 21 is connected to the audio signal source 23. An intermediate tap 21 c is drawn out to the secondary winding 21 b of the input transformer 21. The intermediate tap 21c is connected (grounded) to the reference potential of the circuit. The negative terminal of the DC power source 22 is connected. Further, the intermediate tap 21c is also connected to the conductive film 16a formed on the protective film 16 on the user's ear side, and grounds the conductive film 16a.

  The positive terminal of the DC power source 22 is connected to the metal film formed on the diaphragm 11. In addition, one end of the secondary winding 21 b of the input transformer 21 is connected to the one fixed pole 13. The other end of the secondary winding 21 b is connected to the other fixed pole 13.

  The DC power source 22 applies a polarization voltage of, for example, about 500 V to the metal film formed on the diaphragm 11. Further, the signal voltage applied from the audio signal source 23 to the primary side winding 21a of the input transformer 21 is set in such a way that one side is in a positive phase and the other is in a reverse phase by the secondary side winding 21b. Added to each pole 13.

With this circuit configuration, the diaphragm 11 is driven by a push-pull action by the fixed poles 13 on both sides, and vibrates based on the audio signal from the audio signal source 23 to generate an audio wave.
The sound wave generated by the diaphragm 11 is emitted toward the user's ear through a plurality of through holes 13 a provided in the fixed pole 13.

FIG. 4 is a cross-sectional view showing the overall configuration of the condenser headphone 31 in which the above-described condenser headphone unit 1 is accommodated in the headphone housing in a state of being mounted on the user's temporal region.
The capacitor headphone 31 includes a baffle plate 32 as a support substrate. An annular ear pad 33 that covers the outer ear 37 a of the user 37 is attached to the periphery of one surface of the baffle plate 32. The condenser headphone unit 1 is mounted in a circular opening formed at the center of the baffle plate 32. Further, a bowl-shaped housing 34 is attached to the baffle plate 32 so as to cover the back surface of the capacitor headphone unit 1.

According to the condenser headphones configured as described above, a metal material having high mass and rigidity can be used as the fixed pole 13 of the condenser headphone unit 1 that functions as a driver. Therefore, the headphones described in this embodiment can realize high-quality sound wave reproduction.
In addition, since the conductive film 16a formed on the protective film 16 facing the user's 37 ear side is grounded as described above, it effectively functions as an electric shock prevention measure for the user 37.
In addition, by disposing the second protective film so as to cover the fixed pole located on the side opposite to the user's ear side, both sides of the capacitor headphone unit 1 are covered with the protective film 16 and sealed. Is done. This effectively functions as a moisture-proof measure and a dust-proof measure that prevents suction of dust due to the action of static electricity.

The embodiment described above relates to a condenser headphone using a polarized power supply (DC power supply 22), but is not limited to the above-described embodiment. The present invention can also be used for a condenser headphone using an electret material made of a polymer film instead of the above-described polarized power source.
Although the condenser headphones using the electret material are not shown, electret dielectric films are respectively attached to the inner surfaces of the pair of fixed poles 13 and 13 shown in FIGS. 2 and 3 facing the diaphragm 11. The The electret dielectric film is made of a polymer film such as FEP (fluoroethylene polymer). A pair of fixed poles 13 and 13 are applied with signal voltages having opposite phases.

Generally, in the above-described condenser headphones using the electret material, when an external charge acts on the electret material via a human body or the like, there arises a problem that the electret material is deteriorated.
Also in this case, similarly to the example shown in FIGS. 2 and 3, the human body and the electret are formed by electrically grounding the conductive film 16 a formed on the protective film 16 located on the ear side of the user 37. The material can be shielded electrostatically. Therefore, it is possible to effectively prevent the above-described electret material from being deteriorated.

DESCRIPTION OF SYMBOLS 1 Capacitor headphone unit 11 Diaphragm 12 Support ring 13 Fixed pole 13a Through-hole 14 Insulation seat 14a Recessed part 16 Protective film 16a Conductive film 17 Support member 21 Input transformer 21a Primary side winding 21b Secondary side winding 21c Middle tap 22 DC power supply 23 Audio signal source 31 Capacitor headphones 32 Baffle plate 33 Ear pad 34 Housing 37 User 37a User's outer ear

Claims (5)

A capacitor headphone unit including a diaphragm and fixed poles each provided with a plurality of through holes on both sides of the diaphragm is used, and each of the fixed poles is formed of a metal material and is on the user's ear side A protective film is disposed so as to cover the fixed electrode located on the side, and a second protective film is disposed so as to cover the fixed electrode located on the side opposite to the user's ear side,
A conductive film is formed on a surface of the protective film facing the user's ear, the conductive film is electrically grounded , and the conductive film formed on the second protective film is electrically Capacitor headphones , wherein the protective film and the second protective film are each provided with irregular wrinkles over the entire surface .   The metal plate is formed on the diaphragm, and a polarization voltage is applied to the metal film, and signal voltages having opposite phases to each other are applied to the fixed electrodes. The listed condenser headphones.   The electret material made of a polymer film is disposed on the surface of each fixed pole facing the diaphragm, and signal voltages having opposite phases to each other are applied to the fixed poles. 1. Capacitor headphones described in 1. Protective film covering the fixed pole located on the ear side of the user, with its peripheral edge portion is supported by the support member, attached to the fixed pole which is arranged on the ear side of the front SL using support member user The condenser headphone according to any one of claims 1 to 3, wherein the condenser headphone is provided. The second protective film, characterized in that the peripheral edge portion thereof while being supported by the support member, is attached to the fixed pole located on the opposite side of the ear side of the front Symbol used by utilizing the support member's The capacitor headphone according to any one of claims 1 to 3.

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