JP2009278167A - Noise canceling type headphone - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a noise canceling type headphone capable of preventing the disturbance of musical sounds caused by unexpected noise canceling sounds by preventing resonant sounds near an outside sound taking port which are listened to as sounds having no relation to original outside sounds from being taken into a microscope. <P>SOLUTION: A headphone housing 4 integrated with a baffle plate 3 in which a head pad 2 covering each of ears of a user on an outer peripheral portion to constitute an enclosure and equipped with an outside sound taking port 4A on one part is provided with an acoustic tube 20 having one end on the outside sound taking port 4A and the other end extending in the enclosure, an omnidirectional microphone 12 is provided on the other end of the acoustic tube 20 and an acoustic resistance material 21 is disposed in the acoustic tube 20. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a noise-canceling headphone, and more particularly to a configuration for preventing a sound different from the original external noise generated in the headphone peripheral portion from being taken in as noise.

  As is well known, a sealed headphone is known as a personal speaker that is used by being worn on the head while covering the periphery of the user's ear, and one of them is a noise canceling headphone.

  The noise-canceling headphones include a microphone that collects external noise and converts it into an electrical signal (hereinafter referred to as “external noise signal”), and phase-inverts the external noise signal converted by the microphone. Thus, a noise cancellation signal is generated, and this noise cancellation signal is added to the audio signal or audio signal to be distributed, and the noise is canceled by emitting the sound from headphones or speakers (for example, Patent Document 1).

As a conventional example of a sealed noise-canceling headphone, for example, there is one configured as shown in FIG.
In FIG. 2, a sealed noise-canceling headphone 1 is mounted on a user's head and pressed against the peripheral part of the ear, whereby a head pad 2 that performs sound insulation between the inside and outside of the headphone 1 and the head pad. 2 includes a baffle plate 3 provided on an outer peripheral portion and supporting an electroacoustic conversion unit SS described later. The electroacoustic conversion unit SS can also be called a speaker portion, and has the same configuration as the speaker.

On the opposite side of the head pad 2 with the baffle plate 3 in between, a headphone housing 4 constituting an enclosure portion E as a closed space separated from the sound generating portion by the baffle plate 3 is provided.
The baffle plate 3 is provided with a circular opening 3 </ b> A in the center, and an electroacoustic conversion unit SS that constitutes a speaker portion is supported via a headphone unit frame 5.
That is, the headphone unit frame 5 having a cylindrical opening 5A at the center is fitted and integrated with the opening 3A of the baffle plate 3, and the headphone unit frame 5 is equipped with the electroacoustic conversion unit SS.

The electroacoustic conversion unit SS is fixed to a petri dish-shaped yoke 6 fixed in the opening 5A of the headphone unit frame 5, a flat magnet 7 fixed to the center of the inner bottom of the yoke 6, and an end surface of the magnet 7. The pole piece 8, the dome-shaped diaphragm 9, and the voice coil 10 that is integrated with the diaphragm 9 and is wound around the pole piece 8 in a cylindrical shape. The voice coil 10 is in a cylindrical magnetic gap formed between the inner peripheral surface of the peripheral wall of the yoke 6 and the outer peripheral surface of the pole piece 8. Driven by the electromagnetic force of the magnetic field in the magnetic gap and the audio signal supplied to the voice coil 10, the voice coil 10 and the diaphragm 9 integrated therewith vibrate according to the audio signal.
The power supply control to the voice coil 10 is performed via a noise cancellation circuit provided on the printed board 11 attached to the baffle plate 3.

  On the other hand, an omnidirectional microphone 12 having a sound collecting function around the headphones is used as a microphone for listening to external noise. The omnidirectional microphone 12 is installed inside an external sound intake port 4A provided so as to penetrate a part of the headphone housing 4.

JP-T-2004-526375

The microphone installation structure shown in FIG. 2 has a problem that sound other than the original external noise is generated at the external sound intake port 4A for the following reason.
That is, the structure of the external sound intake port formed in the headphone housing 4 is similar to an air column tube in which one end is opened and the other end, that is, the end on the headphone housing 4 side is closed by the microphone 12. Resonance noise may be generated by the incoming airflow.

Resonance sound is different from the sound that originally becomes external noise. Therefore, when a noise cancellation signal corresponding to this resonance sound is generated, even if there is no external noise, a sound having an opposite phase for canceling noise according to the noise cancellation signal is generated from the electroacoustic unit. become. The sound with the opposite phase is a sound that is unrelated to the external noise to be canceled. There is a risk that a sound unrelated to the external noise may inadvertently disturb the pronunciation of the musical tone signal.
Therefore, it is conceivable to provide a hood or a wind screen outside the intake port so as not to collect resonance sound generated at the intake port 4A. However, a member different from the headphones is greatly projected on the outer surface of the headphone housing 4. This is disadvantageous in terms of design.
Although it is conceivable to fill the intake port 4A with a nonwoven fabric or the like, since the length in the penetration direction of the intake port is limited to the thickness of the headphone housing 4, an attenuation rate with respect to the wavelength of the resonance sound is obtained. Is an insufficient length, and as a result, it may not be possible to eliminate the resonance generated at the inlet 4A.

  The object of the present invention is to take into account the problems in the above conventional sealed noise-canceling headphones, and that the resonance sound near the external sound intake port that is heard as a sound unrelated to the original external noise is captured by the microphone. It is to prevent. More specifically, it is an object of the present invention to provide a noise-cancellation type headphone that can prevent an unintentional noise-canceling phenomenon from occurring and prevent an original sound signal from being generated.

In order to achieve this object, according to the present invention, an acoustic tube extended from the external sound intake port toward the inside of the enclosure is disposed at the external sound intake port, and the external sound intake port of the acoustic tube is Is characterized in that the omnidirectional microphone is arranged at the opposite end, and an acoustic resistance material is arranged in the acoustic tube.
The acoustic resistance material can be provided in the entire region of the acoustic tube, in part, or in a plurality of locations. When the acoustic resistance material is provided in a plurality of locations, different acoustic resistance can be provided.

  Since an acoustic tube continuous with the external sound intake port provided in the headphone housing is located, the sound pressure of the resonance sound on the sound entrance side of the acoustic tube can be reduced. Depending on the sound pressure and wavelength of the resonance sound, it may enter the inside of the acoustic tube, but it is possible to suppress the resonance sound from reaching the position of the microphone by the acoustic resistance material located inside.

  Thereby, it is possible to prevent the microphone from taking in a resonance sound different from the original external noise. As a result, inadvertent noise cancellation processing due to the entry of the resonance sound is prevented, so that the quality of sound produced by the musical sound signal can be prevented from being impaired.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing an embodiment of a noise canceling type headphone according to the present invention according to FIG. Among the components shown in FIG. 1, the same components as those shown in FIG. 2 are denoted by the same reference numerals, and components different from the configuration shown in FIG.

  In FIG. 1, a noise cancellation type headphone (indicated by reference numeral 100 for convenience) according to an embodiment of the present invention is provided with a cylindrical acoustic tube 20 inside an external sound intake port 4A provided in a headphone housing 4, An acoustic resistance material 21 is loaded inside the acoustic tube 20, and an omnidirectional microphone is disposed at the end of the acoustic tube 20 opposite to the external sound intake port 4A.

  The acoustic tube 20 is connected at one end to an external sound intake port 4A formed in the headphone housing 4, the other end is extended toward the enclosure part E, and the omnidirectional microphone 12 is attached to the other end. ing. In the illustrated embodiment, the acoustic tube 20 is integrally formed with resin or the like together with the headphone housing 4. However, the acoustic tube 20 is manufactured as a separate member from the headphone housing 4, and one end of the acoustic tube 20 is taken in the external sound of the headphone housing 4. It may be connected to the mouth 4A.

The acoustic tube 20 is set to a length that is longer than the thickness of the headphone housing 4 and that can substantially eliminate the sound pressure of the resonance sound caused by the airflow flowing along the outer surface of the headphone housing 4 on the external sound intake port 4A side. Yes.
Considering that the resonance sound has a different wavelength from that of the sound that is captured as the original external noise, the length for canceling the resonance is selected by selecting a length corresponding to the wavelength different from the resonance sound. It is designed to prevent resonance in the tube.

However, in some cases, the length may not be obtained. Therefore, an acoustic resistance material 21 is loaded inside the acoustic tube 20 in order to surely attenuate the resonance sound.
The acoustic resistance material 21 is made of a member having an appropriate acoustic resistance, such as sponge or non-woven fabric, and is loaded in the entire length direction of the acoustic tube 20 or a position near the microphone 12.

  The embodiment according to the present invention is configured as described above, so that even when a resonance sound is generated by the airflow passing through the external sound intake port 4A formed in the headphone housing 4, the sound pressure is generated by the acoustic tube 20. Attenuated. Therefore, the sound pressure of the resonance sound reaching the microphone 12 can be extremely reduced. In particular, the resonance sound that has entered the inside of the acoustic tube 20 is surely attenuated by the acoustic resistance material 21, so that the resonance sound hardly reaches the microphone 12.

  As described above, since it is possible to prevent the microphone 12 from listening to the resonance sound generated from the external sound intake port 4A, which is different from the original external noise, noise cancellation processing for the resonance sound is performed. Will be prevented. As a result, since the sound other than the cancel sound that is originally executed for the external noise is not generated, the musical sound signal is not disturbed.

  As the configuration of the acoustic resistance material 21, as shown in FIG. 1 (B), materials having different acoustic resistances in the length direction of the acoustic tube 20 can be dispersed and arranged at a plurality of locations. In order to make the acoustic resistance materials 21A, 21B, and 21C different from each other, the density, length, number, and the like of the acoustic resistance materials may be appropriately selected. Thereby, it is possible to deal with a wide range with respect to the sound pressure and frequency of the resonance sound. In addition, since the acoustic resistance material exists in a plurality of stages, it is possible to reliably suppress the resonance sound from acting on the microphone.

In such a configuration, for example, a directional microphone obtained by placing a microphone oppositely in a straight tube portion, unlike a straight tube type inner earphone in which a pad is inserted in the ear so that a musical sound can be heard. However, a particularly remarkable effect is obtained when an omnidirectional microphone is used.
The acoustic resistance material 21 is not limited to the above-described sponge, but may be any material that can be attenuated by sound absorption and prevented from entering by reflection. In the latter case, it is necessary to allow the entry of the original external noise.

An embodiment of the noise cancellation type headphones of the present invention is shown, in which (A) is a sectional view thereof, and (B) is a sectional view showing a modification of an acoustic tube applicable to the present invention. It is sectional drawing which shows the prior art example of the noise cancellation type | mold headphones for demonstrating the external noise capture | acquisition structure in a noise cancellation type | mold headphones.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Noise cancellation type headphones 2 Head pad 3 Baffle board 4 Headphone housing 4A External sound intake 12 Microphone 20 Acoustic tube 21 Acoustic resistance material

Claims (3)

A baffle plate having a head pad that covers the periphery of the user's ears on the outer periphery, a headphone housing that is integrated with the baffle plate to form an enclosure, and partly includes an external sound inlet, and the external sound In noise cancellation type headphones equipped with an omnidirectional microphone inside the intake port,
An acoustic tube extended from the external sound intake port into the enclosure is disposed at the external sound intake port,
The omnidirectional microphone is disposed at the end of the acoustic tube opposite to the external sound intake port,
A noise-canceling headphone, wherein an acoustic resistance material is disposed in the acoustic tube.   The noise canceling headphone according to claim 1, wherein the acoustic resistance material is provided in the entire length direction of the acoustic tube or in a part thereof.   The noise canceling headphone according to claim 1, wherein the acoustic resistance material is disposed with different acoustic resistances at a plurality of locations in a length direction of the acoustic tube.

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