JP2008098988A - Headphones - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a noise cancel type headphone configured such that: electric coupling relation between a cancel signal and a musical sound signal is made poor; an influence that the cancel signal exerts on the musical sound signal is reduced; power amplifier circuits for the cancel signal and musical sound signals are not loaded by each other; sound quality is excellent; and even when an internal battery is dead, a reproduced sound based upon the musical sound signal can be listened to. <P>SOLUTION: The a headphone has one speaker unit 50 having one diaphragm 70 and two voice coils 61 and 62 driving the diaphragm 70, and while the musical sound signal is inputted to one voice coil, the noise cancel signal based upon a noise signal detected by a microphone 20 for noise detection is inputted to the other voice coil. The voice coil 60 may have a center tap so that the musical sound signal is inputted to one end side of the voice coil and the noise cancel signal is inputted to the other end side of the voice coil. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to headphones that can reduce external noise.

  With the popularization of portable music players, headphones are also widely used. Portable music players are often used in streets with high noise levels and in vehicles such as trains and buses, and external noises can be heard through headphones as well as music played by the player. When listening to music in the noise, the music may be drowned out by external noise. May cause unpleasant feelings. In addition, even when high-quality musical sounds are played back with headphones, noise entering from the outside may affect the quality of the playback sound that can be heard by the user.

  Accordingly, noise canceling headphones that are designed to cancel noise entering from the outside so that only the musical sound can be heard by the user's ear are becoming widespread. The principle of the noise canceling headphone is to detect noise entering the headphone with a microphone, generate canceling noise having a phase opposite to the detected noise signal, and cancel the noise with the canceling noise. A typical noise-canceling headphone has one speaker and thus one voice coil. The noise signal collected by the microphone and converted into an electrical signal is passed through a filter and delay circuit to generate a noise cancellation signal with the opposite phase to the noise signal, and this noise cancellation signal and the target music signal are synthesized (added) ) Is then amplified and input to one voice coil of the one speaker.

The sound output from the speaker is a combination of a noise cancellation signal and a musical tone signal converted into sound, and the sound converted from the noise cancellation signal cancels external noise entering the headphones and enters the user's ear. The sound is only the sound converted from the musical sound signal.
Alternatively, there is a method of synthesizing the noise cancellation signal and the tone signal immediately before the one voice coil after individually amplifying the power of the noise cancellation signal and the tone signal. However, since the two power amplifiers are connected to the voice coil in series or in parallel, there is a problem that the two power amplifiers become loads with each other.

  FIG. 4 shows an example of a conventional noise cancellation type headphone. In FIG. 4, a flange member 2 is coupled to an open end of a bottomed tubular headphone housing 1, and a head pad 3 is fixed to the outer surface (left side in FIG. 4) of the flange member 2. . When the user uses the headphones, the outer end surface of the head pad 3 hits the user's head side surface, and the user's ear 13 is positioned in the space surrounded by the head pad 3. The flange member 2 has a window hole in the center and is formed in a ring shape. A headphone unit 5 is fixed to the inner end surface (right end surface in FIG. 4) of the flange member 2 so as to close the window hole. ing. The headphone unit 5 includes a flat petri dish-like base 6, a petri dish-like yoke 7 having a smaller diameter and flatter than the base 6 fitted in the inner bottom part of the base 6, and a flattery part fixed to the center of the inner bottom part of the yoke 7. A magnet 8, a plate-shaped pole piece 9 fixed to the end face of the magnet 8, a voice coil 10 wound in a cylindrical shape, and a dome-shaped diaphragm 12 are provided.

  The open end surface of the petri dish-shaped yoke 7 and the end surface of the pole piece 9 are substantially flush with each other, and a ring-shaped gap is formed between the outer peripheral surface of the pole piece 9 and the inner peripheral surface of the open end side of the yoke 7. The voice coil 10 enters the gap. A magnetic field using the magnet 8 as a source is formed in the ring-shaped gap, and the voice coil 10 exists in the magnetic field. The diaphragm 12 has a dome-shaped edge portion that surrounds a dome portion at the center, and the outer periphery of the edge portion is fixed to the base 6 so that the diaphragm 12 is supported so as to vibrate. One end of the voice coil 10 is fixed to the boundary between the central dome portion and the edge portion of the diaphragm 12, and the voice coil 10 is supported so as not to contact the yoke 7 and the pole piece 9. A musical tone signal is input to the voice coil 10 from a power amplifier (driver) of an external player, and the voice coil 10 is driven back and forth in accordance with the musical tone signal. It is done. This sound reaches the user's ear 13 surrounded by the head pad 3 through the window hole of the flange member 2.

  The above description is a description of a general headphone. In the noise canceling type headphone, a microphone for detecting ambient noise and a noise canceling signal having a phase opposite to that of the noise detected by the microphone are generated in the above configuration. A signal processing circuit such as a synthesis circuit for synthesizing (adding) the generated noise cancellation signal with the musical tone signal and inputting the resultant signal to the voice coil 10 is added. Various ideas are applied to the position of the microphone and the configuration of the signal processing circuit. In FIG. 4, M1 to M4 show various examples of arrangement positions of the noise detection microphones. M1 is an example arranged inside the headphones, and is an example arranged outside in the space immediately before the diaphragm 12. M2 to M4 are examples arranged on the outside of the headphones, M2 is an example arranged on the top of the flange member 2, M3 is arranged on the bottom of the flange member 2, and M4 is an example arranged on the outside surface of the housing 1.

  In the noise-canceling headphones, various ideas have been made to cancel external noise more effectively. For example, in the headphones described in Patent Document 1, a small cavity is provided between a diaphragm (speaker diaphragm) and the ear canal in order to reduce noise while having a relatively constant frequency response, and the diaphragm is provided in the cavity. A microphone is arranged in the vicinity of the microphone, and a feedback signal based on the output of the microphone is coupled to an input electric signal reproduced by the headphones, and the combined signal is amplified to drive the diaphragm. In the conventional example shown in FIG. 4, a microphone is arranged at a position indicated by reference numeral M1.

In the invention described in Patent Document 2, a microphone unit is disposed through a vibration isolation member in a headphone unit used for an active noise control headphone in order to enhance a noise canceling effect.
Although the invention described in Patent Document 1 and the invention described in Patent Document 2 are aimed at improving the performance of the noise canceling type headphones, the object of the present invention described later cannot be achieved.

  The following are known techniques related to the configuration of the present invention. One of them is one in which two voice coils act on one magnetic circuit, and is configured to drive two diaphragms with one magnetic circuit (see Patent Document 3). ). One voice coil and one diaphragm, and another voice coil and another diaphragm are paired. One diaphragm can function as a speaker, and the other diaphragm can function as a sounder, that is, as a ringing sound generating means such as a mobile phone. Alternatively, both a dynamic type speaker and a magnetic type function can be provided.

  As a related invention of Patent Document 3, a first diaphragm that generates sound by a magnetic circuit and a voice coil is provided, and the entire magnetic circuit is supported by a second diaphragm so as to be freely slidable with respect to the casing. There is known a vibration / speaker unit configured such that when sound is generated by a diaphragm, a magnetic circuit supported by a second diaphragm is vibrated and transmitted to a casing (see Patent Document 4). Patent Document 4 describes that the vibration of the casing by the second diaphragm can be used as a vibrator in a mobile phone or as a low-frequency vibration of headphones.

JP-A-6-343195 Japanese Utility Model Publication No. 5-36991 JP-A-11-252683 JP 2000-165987 A

  An object of the present invention is to eliminate the problems of the conventional noise canceling headphones. That is, in the conventional noise cancellation headphones, the signal for canceling the noise and the musical sound signal are electrically combined and combined and pass through the signal processing circuit, so that the musical sound signal is affected by the noise cancellation signal and the sound quality is improved. to degrade. Moreover, in a case where the noise is cancelled, a sound quality difference may occur between the case where the noise canceling operation is performed and the case where the noise canceling operation is not performed.

  The present invention reduces the influence of the noise cancellation signal on the musical tone signal by reducing the electrical coupling relationship including the magnetic coupling and the electrostatic coupling between the noise cancellation signal and the musical tone signal as much as possible. It is an object of the present invention to provide a noise canceling type headphone with good sound quality, in which the power amplifying circuit and the power amplifying circuit for the musical sound signal do not load each other.

  The present invention is also a noise that can extend the life of the built-in battery by allowing the noise to be canceled even if the power of the noise cancellation signal input to the voice coil for canceling the noise is small. It is an object to provide a canceling type of headphones. Even if the built-in battery is depleted and the noise canceling circuit does not operate, it is possible to provide a noise canceling type headphone that can listen to the playback sound based on the musical tone signal in the same way as general headphones without a noise canceling function. Objective.

The present invention includes a speaker unit having one diaphragm and two voice coils that drive the one diaphragm. One voice coil has a tone signal and the other voice coil has a voice signal. The most important feature is to input a noise cancellation signal based on the noise signal detected by the noise detection microphone.
Alternatively, it has one loudspeaker unit having a diaphragm and a voice coil with a center tap for driving the diaphragm, and a music signal is transmitted between one end of the voice coil and the center tap. A noise cancel signal based on a noise signal detected by a noise detection microphone is input between the other end and the center tap.

Voice coils that are substantially different from each other are driven by the tone signal and noise cancellation signal, and the noise inside the headphones is acoustically canceled by the reverse-phase sound based on the noise cancellation signal, and only the sound based on the tone signal is received in the user's ear. Will arrive. Substantially different voice coils are driven by individual power amplifiers (drivers), and since the electrical coupling between the two is shallow, the musical sound signal is less affected by the noise cancellation signal, and the musical sound signal is reproduced with high sound quality. Can do.
If the sound insulation effect of the headphones is increased, the noise can be canceled even if the power of the noise cancellation signal input to the voice coil for canceling the noise is small, so that the life of the internal battery is extended. Can do. Even if the built-in battery is exhausted and the noise cancellation circuit stops operating, the voice coil driven by the musical tone signal operates in the same way as a voice coil of general headphones without a noise canceling function, so it is based on the musical tone signal. Listen to the sound.

  Embodiments of the headphones according to the present invention will be described below with reference to FIGS. Since the configuration of the headphone housing and its surroundings, for example, the head pad, may be the same as that of the conventional example shown in FIG. 4, the description will focus on the headphone unit and its drive circuit that constitute the main part of the present invention.

  1 and 2, reference numeral 60 denotes a voice coil, and 70 denotes a diaphragm. The diaphragm 70 includes a central diaphragm main body 71 formed in a dome shape and a dome-shaped edge portion 72 formed to surround the periphery of the diaphragm main body 71, and an outer peripheral edge portion of the edge portion 72. Is fixed to the base 56. A portion of the base 56 facing the diaphragm 70 is recessed so that the diaphragm 70 is supported in a state of floating from the base 56. The voice coil 60 is obtained by winding a thin wire rod into a cylindrical shape, and one end of the cylinder is fixed to a boundary position between the diaphragm main body 71 and the edge portion 72 of the diaphragm 70. The voice coil 60 includes a first voice coil 61 and a second voice coil 62, and the two voice coils 61 and 62 are fixed to one diaphragm 70 to drive one diaphragm 70. It is characterized in that it is.

  FIG. 3 shows an example of windings for obtaining the voice coil 60. In FIG. 3, first, a wire material to be the first voice coil 61 is in close contact with the outer periphery of the winding jig, and is sequentially wound in layers, and then folded and overlapped to form a two-layer voice coil. This is the first voice coil 61, and the terminal wires 63 at both ends thereof are drawn out from the same position. In FIG. 3, the numbers 1 to 8 shown for each turn of the winding are the first layer, and the numbers 9 to 15 are the second layer. Next, the wire material to be the first voice coil 61 is closely wound on the first voice coil 61 in the same manner and wound in order, and then folded and overlapped to form a two-layer voice coil. . Therefore, the overall structure is four layers. This is the second voice coil 62, and the terminal wires 64 at both ends thereof are drawn out from the same position. However, it is drawn out from a position different from the terminal line 63 of the first voice coil 61, for example, from the opposite side across the center of the voice coil 60. In FIG. 3, the numbers 16 to 23 shown for each turn of the winding are the third layer, and 24 to 30 are the fourth layer. In the example shown in FIG. 2, the terminal line 63 of the first voice coil 61 and the terminal line 64 of the second voice coil 62 are drawn from opposite sides across the center of the base 56. It is convenient for assembling the headphone unit that the terminal wires at both ends of the first and second voice coils are drawn out from the same position as a pair. For this purpose, each of the first and second voice coils may be wound an even number of turns. .

  In FIG. 2, the diaphragm 70, the voice coil 60, and the base 56 constitute a part of the headphone unit 50. The headphone unit 50 includes a yoke 57, a magnet 58, and a pole piece 59 in addition to the diaphragm 70, the voice coil 60, and the base 56. The base 56 is a flat petri dish-like member, and a petri dish-like yoke 57 that is smaller in diameter and flatter than the base 56 is fitted in the inner bottom portion of the base 56. A flat magnet 58 is fixed to the center of the inner bottom portion of the yoke 57, and a plate-shaped pole piece 59 is fixed to the front end (left end in FIG. 2) surface of the magnet 58. The open end surface of the petri dish-shaped yoke 7 and the end surface of the pole piece 9 are substantially flush with each other, and a ring-shaped gap is formed between the outer peripheral surface of the pole piece 9 and the inner peripheral surface of the open end side of the yoke 7. Is formed. The voice coil 60 wound in a cylindrical shape and fixed to the diaphragm 70 enters the gap. A magnetic field using the magnet 8 as a source is formed in the ring-shaped gap, and the voice coil 60 is present in this magnetic field. The voice coil 60 is separated from the outer peripheral surface of the pole piece 9 and the inner peripheral surface of the open end side of the yoke 7. In order to allow the base plate 56 to freely vibrate the space surrounded by the base 56 and the diaphragm 70 so that the diaphragm 70 can freely vibrate, a plurality of bases 56 are penetrated in the thickness direction. A hole 561 is formed.

  The headphone unit 50 configured as described above is incorporated in a headphone housing as shown in FIG. 4, and a head pad is provided in the headphone housing to constitute a headphone.

  FIG. 1 shows a drive circuit example of the headphones described above. In FIG. 1, a voice coil 60 that drives one diaphragm 70 includes two voice coils 61 and 62. A noise detecting microphone 20 is disposed at an appropriate position outside or inside the headphones. The noise signal detected and converted by the microphone 20 is input to the signal processing circuit 21. The signal processing circuit 21 performs appropriate signal processing such as generating a noise cancellation signal having an opposite phase to the noise signal detected by the microphone 20. The signal processing circuit 21 may be configured by an analog signal processing circuit, or may be configured by, for example, a DSP (digital signal processing circuit) that processes as a digital signal. The noise cancellation signal output from the signal processing circuit 21 is input to the power amplifier circuit 22, and the first voice coil 61 is driven by the power amplifier circuit 22. The headphone incorporates a power supply battery 23, and the built-in battery 23 serves as a power source for operating the signal processing circuit 21 and the power amplification circuit 22. The second voice coil 62 is connected to a CD player, an MP3 player, or any other player, and is driven by a musical sound signal via the power amplification circuit of the player. Note that the first voice coil 61 may be driven by a tone signal, and the second voice coil 62 may be driven by a noise cancel signal.

According to the embodiment described above, since the voice coil to which only the noise canceling signal is input and the voice coil to which only the musical tone signal is input are provided, the noise canceling signal and the musical tone signal are the drive unit of the diaphragm 70, that is, The voice coil 60 is mechanically synthesized at the portion where the voice coil 60 is fixed to the diaphragm 70. Therefore, since the electrical coupling of the first and second voice coils is shallow both electrostatically and magnetically, both power amplifier circuits do not become loads on each other, and the tone signal is influenced by the noise signal. Therefore, it is possible to obtain a reproduced sound with good sound quality.
Since the power of the noise cancellation signal applied to the noise canceling voice coil is small if the sound insulation design of the headphones is good, there is an advantage that the life of the built-in battery can be extended.
Even if the built-in battery is exhausted, the sound can be reproduced based on the musical sound signal if the musical sound signal is input from the player.

  The voice coil may be substantially the same as having the first voice coil and the second voice coil by continuously winding and winding one thin wire and taking out a center tap. The musical tone signal is input between one end of the voice coil and the center tap, and the noise cancellation signal based on the noise signal detected by the noise detection microphone is input between the other end of the voice coil and the center tap, thereby the first embodiment. The same effect can be obtained. By connecting one end of each of the first and second voice coils in the first embodiment, the same configuration as that in which the center tap is provided is obtained.

It is an electric circuit diagram showing an example of headphones according to the present invention. It is a longitudinal cross-sectional view which shows the principal part of the Example of the headphones concerning this invention. It is a schematic diagram which shows the example of the manufacturing method and structural example of a voice coil applicable to the headphones concerning this invention. It is a longitudinal cross-sectional view which shows the example of the conventional headphones.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Noise detection microphone 21 Signal processing circuit 22 Power amplification circuit 23 Built-in battery 50 Headphone unit 60 Voice coil 61 1st voice coil 62 2nd voice coil 70 Diaphragm

Claims (5)

It has one speaker unit with one diaphragm and two voice coils that drive this one diaphragm.
A headphone, wherein a musical tone signal is input to one voice coil, and a noise cancellation signal based on a noise signal detected by a noise detecting microphone is input to the other voice coil. It has one speaker unit equipped with one diaphragm and a voice coil with a center tap that drives this one diaphragm.
A headphone, wherein a musical tone signal is input between one end of the voice coil and the center tap, and a noise cancellation signal based on a noise signal detected by a noise detecting microphone is input between the other end of the voice coil and the center tap.   The headphone according to claim 1 or 2, wherein the noise cancellation signal is input to the voice coil via a power amplifier that operates using the internal battery as a power source.   The headphone according to claim 1, wherein one of the one voice coil and the other voice coil is layered on the other. The headphone according to claim 1, wherein one voice coil and the other voice coil are respectively wound on a plurality of layers, and both ends of the one voice coil and both ends of the other voice coil are drawn from different positions.

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