JP5430239B2 - Condenser headphone unit - Google Patents

Description

  The present invention relates to a condenser headphone unit, and more particularly, to a diaphragm braking acoustic resistor that brakes a diaphragm.

  In the capacitor headphone unit, for example, with a predetermined DC voltage applied to the diaphragm side, an AC voltage by an audio signal is applied to the fixed pole side, and electrostatic attraction and repulsive force generated between the diaphragm and the fixed pole A diaphragm is driven (for example, refer patent document 1).

  A sound pressure of about 100 dBSPL can be obtained when the voltage applied to the fixed pole is about 100 Vrms, and sound waves generated with the vibration of the diaphragm are emitted through the sound holes formed in the fixed pole.

  In a condenser headphone unit, the resistance of a thin air layer existing between the diaphragm and the fixed pole is usually used for acoustic braking of the diaphragm, but the resistance value needs to be adjusted after assembly. There is a case.

  As one of the adjustment methods, when adjusting only by the resistance of the thin air layer, the optimum resistance value can be changed by variously changing the distance between the diaphragm and the fixed pole, the number of sound holes and / or the diameter of the sound holes. However, this requires a lot of prototypes, which is costly and time consuming.

  As another adjustment method, there is a method of attaching an acoustic resistance material made of a fiber such as a felt material to the fixed pole so as to cover the sound hole, but even with this method, selection of the material and thickness of the acoustic resistance material is possible. In addition to the time required for this, if the fibers of the acoustic resistance material enter the thin air layer through the sound holes and hit the diaphragm, problems such as poor insulation may occur.

No. 2006-41567

  Accordingly, an object of the present invention is to make it possible to easily adjust the braking of the diaphragm in the condenser headphone unit.

In order to solve the above-described problem, the present invention includes a diaphragm, and a fixed pole disposed opposite to the diaphragm via a first thin air layer having almost no mass reactance . In the condenser headphone unit in which a plurality of sound holes are formed in a portion facing the effective vibration portion of the diaphragm,
A resistance plate arranged in parallel with the fixed pole via a second thin air layer having almost no mass reactance is provided on the anti-vibration side of the fixed pole, and the resistance plate includes vibrations of the diaphragm. And a plurality of acoustic resistance holes for adjusting acoustic resistance against sound waves generated and passing through the sound holes of the fixed pole are formed, and the acoustic resistance due to the first thin air layer and the sound holes of the fixed pole are formed. , The acoustic resistance due to the second thin air layer, and the acoustic resistance due to the acoustic resistance hole of the resistance plate are connected in series .

  According to a preferred aspect of the present invention, the acoustic resistance hole is disposed at a non-coaxial position with respect to the sound hole.

  In the present invention, it is preferable that the number of the acoustic resistance holes is small in the central portion of the resistance plate and is larger than the number of the central portions in the peripheral portion of the resistance plate.

  Moreover, the hole diameter of the acoustic resistance hole may be a small diameter at the central portion of the resistance plate, and may be increased toward the peripheral portion around the central portion.

  Moreover, it is preferable that the said resistance board is movable to the surface direction with respect to the said fixed pole.

  Moreover, it is preferable that the standing pile is planted in any one surface of the opposing surface of the said fixed pole and the said resistance board.

  The standing pile preferably has a length corresponding to at least the distance between the resistance plate and the fixed pole.

  Moreover, it is preferable that the standing pile is planted on the fixed pole side and is also provided in the sound hole and on the surface side of the fixed pole facing the diaphragm.

According to the present invention, an effective vibration portion of the diaphragm in the fixed pole includes the diaphragm, and the fixed pole disposed opposite to the diaphragm and the first thin air layer having almost no mass reactance. In a condenser headphone unit in which a plurality of sound holes are formed in a portion opposite to the sound hole, the sound is generated on the anti-vibration plate side of the fixed pole (the back side of the fixed pole) along with the vibration of the vibration plate A resistance plate having a plurality of acoustic resistance holes for adjusting acoustic resistance to sound waves is arranged in parallel with the fixed pole via a second thin air layer having almost no mass reactance, so that a sound hole is formed on the back side of the fixed pole. A sound wave path extending from the sound resistance hole to the sound resistance hole is formed, and by changing the position and diameter of the sound resistance hole with respect to the sound hole, the sound resistance of the sound wave path can be adjusted, and the diaphragm can be appropriately braked. Possible It made.

  In addition, by installing an upright pile having a length corresponding to the distance between the resistance plate and the fixed electrode on either one of the opposing surfaces of the fixed electrode and the resistance plate, dust or the like is generated as a sound hole. Can be prevented from entering the thin air layer.

The typical sectional view showing the composition of the capacitor headphone unit concerning the embodiment of the present invention. The front view which shows the fixed pole in the said capacitor | condenser headphone unit. The expanded sectional view which shows the principal part of this invention. The equivalent circuit diagram of the said capacitor headphone unit.

  Next, an embodiment of the present invention will be described with reference to FIGS. 1 to 3, but the present invention is not limited to this.

  Referring to FIG. 1, the capacitor headphone unit according to this embodiment includes a diaphragm 10 and a fixed pole 20, and is housed in a headphone housing including an ear pad (not shown).

  For the diaphragm 10, for example, a thin film such as PPS (polyphenine sulfide) having a gold vapor deposition film may be used. The diaphragm 10 is stretched with a predetermined tension on a diaphragm support ring (diaphragm ring) 11.

  In this embodiment, a circuit board made of a single-sided copper-clad laminate is used for the fixed electrode 20, and the surface of the fixed electrode 20 facing the diaphragm 10 is made of copper foil as shown in FIG. 3. An electrode surface 21 is formed. Unlike this, the fixed electrode 20 may be a metal plate such as aluminum.

  The diaphragm 10 and the fixed pole 20 are disposed to face each other through a thin air layer by a spacer member (not shown). In this embodiment, the fixed pole 20 is disposed only on one side of the diaphragm 10, but in the case of a push-pull type, the fixed pole 20 is disposed on both sides of the diaphragm 10. The condenser headphone unit of this aspect is also included in the present invention.

  By a drive circuit (not shown), for example, a predetermined DC voltage is applied to the diaphragm 10 side, and an AC voltage of an audio signal is applied to the fixed pole 20 side. As a result, the vibration plate 10 vibrates in response to electrostatic attraction and repulsion generated between the vibration plate 10 and the fixed pole 20.

  The fixed pole 20 is provided with a sound hole (hole for passing a sound wave) 22 for emitting a sound wave generated along with the vibration of the diaphragm 10. As shown in FIG. 2, the sound holes 22 are concentrated on the central portion corresponding to the effective vibration portion of the diaphragm 10 in the fixed pole 20.

  FIG. 4 shows an equivalent circuit diagram of the capacitor headphone unit according to this embodiment. In this equivalent circuit diagram, Ze is the impedance of the listener's ear, Za is the radiation impedance to the outside, E is the sound source, sf is the stiffness of the volume in the ear pad, r1 is the acoustic resistance of the sound hole 22, and mo is the diaphragm 10. , So is the stiffness of the diaphragm 10, and s1 is the stiffness of the volume of the thin air layer.

  In the present invention, the braking of the diaphragm 10 is adjusted by changing the acoustic resistance r1 of the sound hole 22. Therefore, the capacitor headphone unit according to this embodiment includes a resistance plate 30 on the anti-vibration plate side (back side) of the fixed pole 20.

  The resistance plate 30 is arranged as a perforated plate having a plurality of acoustic resistance holes 31 in parallel with the fixed pole 20 at a predetermined interval.

  The acoustic resistance hole 31 may have any of the same diameter as the sound hole 22 of the fixed pole 20, a larger diameter than the sound hole 22, and a smaller diameter than the sound hole 22. However, as shown in FIG. It is arranged at a position non-coaxial with the hole 22, that is, at a position shifted from the sound hole 22.

  According to this, a bent sound wave path from the sound hole 22 to the acoustic resistance hole 31 is formed between the fixed electrode 20 and the resistance plate 30 as shown by an arrow A in FIG. By changing the hole diameter and number, the acoustic resistance of the sound wave passage is adjusted, and the diaphragm 10 can be appropriately braked.

  In order to make the length of the sound wave path variable, it is preferable that the resistance plate 30 is movable with respect to the fixed pole 20 in the surface direction (vertical direction in FIG. 3). When the acoustic resistance hole 31 has a smaller diameter than the sound hole 22, it may be arranged coaxially with the sound hole 22.

  Further, by adjusting the arrangement and / or the hole diameter of the acoustic resistance holes 31, it is possible to make a portion that moves easily and a portion that does not move easily.

  That is, in general, the central portion of the diaphragm 10 has a larger vibration amplitude than the peripheral portion, and is easily in contact with the fixed pole 20. Therefore, the number of acoustic resistance holes 31 drilled in the central portion of the resistance plate 30 is reduced, and the number of acoustic resistance holes 31 drilled in the peripheral portion is increased.

  Thereby, a large sound pressure can be obtained while limiting the amplitude of the central portion of the diaphragm 10. As another method, the hole diameter of the acoustic resistance hole 31 may be a small diameter at the central portion of the resistance plate 30 and the diameter of the acoustic resistance hole 31 may be increased toward the peripheral portion around the central portion.

  As described above, according to the present invention, the resistance plate 30 having different hole diameters and arrangements of the acoustic resistance holes 31 is prepared, the resistance plate 30 is changed, and / or the resistance plate 30 is moved with respect to the fixed pole 20. By doing so, the diaphragm 10 can be appropriately braked.

  In the present invention, in order to prevent dust or the like from entering the thin air layer between the diaphragm 10 and the fixed electrode 20 from the sound hole 22, any one of the opposing surfaces of the fixed electrode 20 and the resistance plate 30 is used. The standing pile 41 is planted on one side. The planting density may be appropriately selected according to the expected size of dust.

  The standing pile 41 is preferably provided with a length corresponding to at least the distance between the fixed pole 20 and the resistance plate 30, and more preferably, the standing pile 41 is implanted on the fixed pole 20 side and the sound hole 22. It may be provided also on the electrode surface 21 facing the diaphragm of the inner and fixed poles 20.

  According to this, intrusion of dust from the sound hole 22 can be more effectively prevented, and contact between the diaphragm 10 and the fixed pole 20 at the time of large amplitude can be prevented. It is more preferable to form an insulating film on at least the tip of the standing pile 41.

  The standing pile 41 is preferably a pile for electrostatic flocking such as nylon, polyester, rayon, cotton, etc. As an example, the pile is a nylon pile with a thickness of 1.7 to 3.3 dtex and a length of 0.5 to 0.8 mm is preferably employed.

DESCRIPTION OF SYMBOLS 10 Diaphragm 20 Fixed pole 21 Electrode surface 22 Sound hole 30 Resistance plate 31 Acoustic resistance hole 41 Brushed pile

Claims (8)

A portion of the fixed pole facing the effective vibration portion of the diaphragm, including a diaphragm, and a fixed pole disposed opposite to the diaphragm via a first thin air layer having almost no mass reactance In the condenser headphone unit in which a plurality of sound holes are perforated,
A resistance plate arranged in parallel with the fixed pole via a second thin air layer having almost no mass reactance is provided on the anti-vibration side of the fixed pole, and the resistance plate includes vibrations of the diaphragm. A plurality of acoustic resistance holes for adjusting the acoustic resistance to the sound wave generated along with the sound holes of the fixed pole are formed ,
The acoustic resistance due to the first thin air layer, the acoustic resistance due to the sound hole of the fixed pole, the acoustic resistance due to the second thin air layer, and the acoustic resistance due to the acoustic resistance hole of the resistance plate are connected in series. Capacitor headphone unit characterized by being .   The condenser headphone unit according to claim 1, wherein the acoustic resistance hole is disposed at a non-coaxial position with respect to the sound hole.   3. The capacitor according to claim 1, wherein the number of the acoustic resistance holes is small in a central portion of the resistance plate, and is larger than a number of the central portion in a peripheral portion of the resistance plate. Headphone unit.   The hole diameter of the acoustic resistance hole is a small diameter at a central portion of the resistance plate, and is increased in diameter toward a peripheral portion around the central portion. The capacitor headphone unit according to item 1.   5. The capacitor headphone unit according to claim 1, wherein the resistor plate is movable in a surface direction with respect to the fixed pole. 6.   2. The capacitor headphone unit according to claim 1, wherein a standing pile is planted on one of the opposing surfaces of the fixed pole and the resistance plate.   The capacitor headphone unit according to claim 6, wherein the standing pile has a length corresponding to at least a distance between the resistance plate and the fixed pole.   The said standing pile is planted in the said fixed pole side, and it is provided also in the surface side facing the said diaphragm in the said sound hole and the said fixed pole, The Claim 6 or 7 characterized by the above-mentioned. Condenser headphone unit.

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