JP2008085782A - Receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized and light bone conduction type receiver capable of obtaining a sufficient output level in a low frequency region even when used in the state of opening the external acoustic meatus. <P>SOLUTION: A first acoustic vibration generation source 2A and a second acoustic vibration generation source 2B are provided on both end parts of an arm part 1 which is an elastic body configured such that both ends can be brought into press contact with the periphery of the external acoustic meatus entrance of a human body by elastic force and bent in arcuate shape. A third acoustic vibration generation source 3 is provided on the center part of the arm part 1. The resonance frequency of a vibration system including the third acoustic vibration generation source 3 and the arm part 1 is set to be lower than the resonance frequency of the first and second acoustic vibration generation sources 2A and 2B. Also, at least the center part of the arm part 1 is in a belt shape, and the third acoustic vibration generation source 3 is a piezoelectric bimorph formed by bonding a piezoelectric ceramic to the part of the belt shape. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a bone conduction type receiving device that transmits vibrations generated by an acoustic vibration generation source to a head to sense sound and the like.

  The main components of the acoustic vibration generating source of a receiving device that listens to sound using bone conduction, that is, a bone conduction speaker, are an electromagnetic type and a piezoelectric type. As shown in Patent Documents 1 and 2, the electromagnetic configuration is similar in principle to a structure in which only a diaphragm is reduced in a conventional telephone handset. In this configuration, a vibrating iron piece (plate yoke) faces a yoke excited by a permanent magnet through a spring mechanism. When a current proportional to the sound flows through a winding placed around the yoke, a force proportional to the sound acts on the iron piece and the iron piece vibrates, and the acoustic vibration comes into contact with a force proportional to the sound as a reaction of the vibration. Propagates to an object On the other hand, the piezoelectric method uses a vibration force generated by a piezoelectric bimorph, and is advantageous in reducing the weight and size. Patent Documents 3, 4, and 5 show examples of piezoelectric methods.

Japanese Patent No. 2967777 Japanese Patent No. 3358086 JP 59-140796 A JP 59-178895 A JP 2005-175985 A

  Bone conduction speakers that generate acoustic vibrations from electroacoustic signals are designed to increase the vibration output by designing the resonance frequency of the vibration system in the audible sound range, regardless of whether they are electromagnetic or piezoelectric. If the resonance frequency is set too low, vibrations in the higher-order resonance region are added to the vibrations in the high-frequency portion, resulting in adverse effects such as an increase in distortion and a decrease in sound quality. Therefore, in practice, the resonance frequency is often set around 1 kHz.

  Since driving in the low sound range lower than the resonance frequency of the acoustic vibration generating source is driving in the elastic control region, the acoustic vibration output is small at the low frequency. The output has a frequency characteristic that increases as the frequency increases and reaches a peak at the resonance frequency. As a result, the bone conduction speaker generally lacks low-frequency output, and improvements are desired in many fields of bone conduction applications. The method of increasing the input level to the acoustic vibration source and adjusting the frequency characteristics of the drive input signal with a filter circuit can also be a means of improving the low-frequency sound, but the drive source itself becomes larger and the associated weight increases. Increasing the complexity of the drive circuit is a problem. Further, when the external auditory canal is occluded, the low frequency of the bone conduction sound is greatly increased. However, in many bone conduction applications, it is found that the external auditory canal can be opened and the sound can be heard, and this method is not improved.

  Therefore, an object of the present invention is to provide a small and light bone conduction type receiver that can obtain a sufficient output level in a low frequency region even when used in a state where the external auditory canal is opened.

  In the case of the human head, wherever an acoustic vibrating body is pressed, the vibration propagates to the skull and further to the auditory nerve in the cochlea in the back of the ear, which is called bone conduction. The acoustic vibration is sensed by the auditory nerve and the voice is recognized, but the sensitivity varies greatly depending on the place where the acoustic vibrator is pressed. The most sensitive place to detect acoustic vibration is around the entrance to the ear canal, especially the tragus composed of cartilage is a prominent place, and the sound is recognized most sensitively when the acoustic vibrator is pressed against this part. .

  As described above, the conventional device for receiving voice by bone conduction mainly uses a configuration similar to headphones that listen to existing air conduction sound, and both ends of the arm placed on the top of the head and the arm extending from the back of the head to the auricle. An acoustic vibration generating source is attached to the outer ear canal and fixed around the ear canal entrance.

  As a result of intensive studies, the inventor attached a third acoustic vibration generation source at the center of the arm, and the resonance frequency of the vibration system including this arm is lower than the resonance frequency of the acoustic vibration generation source attached to the tip of the arm. Designed in the area, the acoustic vibration generated from the third acoustic vibration source is propagated to the arm, and the tip of the arm is pressed around the ear canal entrance such as tragus, so that the acoustic vibration attached to the tip of the arm It was confirmed that the shortage of the vibration output level in the region lower than the resonance frequency of the acoustic vibration generated at the source can be compensated. As a result, a sufficient output level can be obtained even at a low frequency of bone transmission sound.

  Further, an appropriate elastic body is used for the arm portion, and the third acoustic vibration generation source is a piezoelectric bimorph or a piezoelectric unimorph, so that the vibration system including the third acoustic vibration generation source and the arm is made into a tuning fork-like vibration. Therefore, it is possible to easily configure a vibration system having a resonance frequency in a low range, and to reduce the size and weight at the same time.

  As described above, the receiving device of the present invention generates the first and second acoustic vibrations at the both end portions of the elastic body bent in an arc shape so that both end portions can be pressed against the periphery of the human ear canal entrance by elastic force. And a third acoustic vibration generating source at the center of the elastic body.

  It is desirable that the resonance frequency of the vibration system including the third acoustic vibration generation source and the elastic body be set lower than the resonance frequencies of the first and second acoustic vibration generation sources.

  Further, it is desirable that at least a part of the elastic body has a band shape, and the third acoustic vibration generating source is a piezoelectric bimorph or a piezoelectric unimorph formed by bonding a piezoelectric ceramic to the band-shaped portion.

  As described above, according to the present invention, it is possible to obtain a small and lightweight bone-conduction receiving device that can obtain a sufficient output level in a low frequency range even when used with the ear canal open.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a front view showing the configuration of an embodiment of a receiver according to the present invention. In FIG. 1, the first acoustic vibration source 2A and the first acoustic vibration source 2A are connected to the both ends of the arm portion 1 which is an elastic body bent in an arc shape so that both ends can be pressed against the periphery of the external auditory canal entrance of the human body. 2 acoustic vibration generation sources 2B, and a third acoustic vibration generation source 3 at the center of the arm 1.

  Further, the resonance frequency of the vibration system including the third acoustic vibration generation source 3 and the arm unit 1 is set to be lower than the resonance frequencies of the first and second acoustic vibration generation sources 2A and 2B.

  Further, at least the central portion of the arm portion 1 has a band shape, and the third acoustic vibration generating source 3 is a piezoelectric bimorph or a piezoelectric unimorph formed by bonding a piezoelectric ceramic to the band-shaped portion.

  Hereinafter, an example of a detailed shape and a manufacturing method of the receiver of this embodiment will be described. The arm part 1 was prepared by preparing a belt-shaped stainless steel plate having a width of 5 mm, a length of 350 mm, and a thickness of 2 mm, and bending the both sides in an arc shape with the center part flat as shown in FIG. The first and second acoustic vibration sources 2A and 2B are attached to both ends with acoustic vibration sources in which a piezoelectric bimorph obtained by bonding two piezoelectric ceramic plates to both surfaces of a metal plate is covered with urethane rubber. This piezoelectric ceramic plate has a laminated structure in order to lower the drive voltage. Using NEC TOKIN's piezoelectric ceramic N10 material, a green sheet is produced, and a paste made of silver-palladium is printed on the internal electrode and laminated. Then, after the organic binder was heat-treated, it was fired at 1000 to 1100 ° C. in the air. After printing the side electrode for taking out the external electrode and the internal electrode for each layer, a piezoelectric element was produced by an electrode baking process at 500 ° C. for 20 minutes. The piezoelectric elements are stacked in four layers in the thickness direction, and the outer dimensions are 30 × 5 × 0.5 mm. The piezoelectric ceramic plate was obtained by applying a direct current of 100 V at room temperature for 10 minutes to perform polarization treatment.

  A piezoelectric bimorph was prepared by bonding two piezoelectric ceramic plates to both sides of a brass plate having a width of 5 mm, a length of 35 mm, and a thickness of 0.2 mm using an epoxy-based adhesive, and a lead wire was soldered. The entire piezoelectric bimorph is covered with urethane rubber to produce a rod-shaped vibrating body having an outer shape of 3 × 6 × 40 mm, and this is used as the first and second acoustic vibration generating sources 2A and 2B with thicknesses at both ends of the arm. It fixed with the double-sided tape of about 1 mm. The two piezoelectric ceramic plates are connected in parallel, and when one is applied with an electric field in the polarization direction, the other takes out the electrode terminal so that an electric field is applied in the direction opposite to the polarization.

  The third acoustic vibration generating source 3 was configured as a bimorph structure by attaching two piezoelectric ceramic plates 4 having the same structure as above to the center of the arm portion 1 on both sides. The resonance frequency of the first and second acoustic vibration sources 2A and 2B is about 1 kHz, and the resonance frequency of the vibration system including the third acoustic vibration source 3 and the arm unit 1 is about 200 to 400 Hz. It adjusted and produced so that it might become.

  In this embodiment, a laminated piezoelectric element is used. However, this is for reducing the driving voltage, and is not essential, and can be constituted by a single plate as necessary. is there.

  FIG. 2 shows that the receiver according to the present embodiment is mounted so that the third acoustic vibration source 3 is placed on the top of the head and the first and second acoustic vibration sources 2A and 2B are applied to both tragus. FIG. When an AC voltage (10 Vrms Max) proportional to the acoustic signal is applied between the electrode terminals of the third acoustic vibration generating source 3, bending vibration proportional to the acoustic signal is generated in the arm unit 1. When the electric signal is supplied only to the first and second acoustic vibration generating sources 2A and 2B without inputting the electric signal to the third acoustic vibration generating source 3, the electric signal is also supplied to the third acoustic vibration generating source 3. When compared with the case where the power is supplied, the volume of the low frequency sound is clearly increased in the latter, and the effect of improving the output level at the low frequency according to the present invention can be clearly confirmed, and the usefulness of the present invention can be confirmed. It was. In addition, the weight of the receiver device prototyped by the above-described shape and manufacturing method is only 20 g because it does not have an extra mechanism, which is lighter than the weight of the conventional receiver device that is several tens of grams or more. Yes.

  FIG. 3 shows a modification of the receiver according to the present embodiment, in which the third acoustic vibration generating source 3 is arranged in the back of the head and the first and second acoustic vibration generating sources 2A and 2B are applied to the periphery of the ear canal. It is a side view which shows the case where it mounts | wears. In this case, the shape of the arm portion 11 is configured such that it is bent halfway and hooked on the auricle, and the acoustic vibration generating sources 2A and 2B at the distal end thereof are in contact with the tragus.

  FIG. 4 is a side view showing a mounting example of the receiver of the present embodiment when the arc-shaped portion of the arm unit 1 and the third acoustic vibration generating source 3 are arranged under the chin like the stethoscope. . Since the whole is lightweight, such mounting is possible.

  As described above, according to the present invention, it is possible to obtain a small and lightweight bone-conduction receiving device that can obtain a sufficient output level in a low frequency range even when used with the ear canal open.

  Needless to say, the present invention is not limited to the above-described embodiment, and for example, a mechanism for expanding and contracting the arm portion as necessary to adjust its length, and a pressure for contacting the tragus at the tip of the arm portion. It is also possible to add a mechanism for adjustment. In addition, it is not necessary to use a metal for the elastic body constituting the arm part, and an organic material having appropriate elasticity and strength can also be used. Moreover, the arm part does not need to be formed integrally. Moreover, it is not necessary to comprise all with the same material, and what combined several materials may be sufficient. As the shape of the arm portion, the tip portion may be a rod shape. The first, second, and third acoustic vibration generation sources may be piezoelectric unimorphs formed of piezoelectric ceramic, and the first and second acoustic vibration generation sources may be electromagnetic types. .

The front view which shows the structure of one Embodiment of the telephone receiver by this invention. The side view at the time of mounting | wearing with the receiving apparatus of this Embodiment mounting a 3rd acoustic vibration generation source on the top of a head so that the 1st and 2nd acoustic vibration generation source may be applied to both tragus. FIG. 10 is a side view showing a modification of the receiver according to the present embodiment, in which a third acoustic vibration source is arranged on the back of the head and the acoustic vibration source is attached so as to be applied to the periphery of the ear canal. The side view which shows the example of mounting | wearing with the receiver of this Embodiment at the time of arrange | positioning the arc-shaped part of an arm part and a 3rd acoustic vibration generation source under a chin like a stethoscope.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 11 Arm part 2A 1st acoustic vibration generation source 2B 2nd acoustic vibration generation source 3 3rd acoustic vibration generation source 4 Piezoelectric ceramic board

Claims (3)

  First and second acoustic vibration sources are provided at both ends of the elastic body bent in an arc shape so that both ends can be pressed against the periphery of the human ear canal entrance by elastic force, and the central portion of the elastic body And a third acoustic vibration source.   The resonance frequency of the vibration system including the third acoustic vibration generation source and the elastic body is set lower than the resonance frequency of the first and second acoustic vibration generation sources. 1. The receiver according to 1.   The elastic body is at least partially band-shaped, and the third acoustic vibration generating source is a piezoelectric bimorph or piezoelectric unimorph formed by bonding a piezoelectric ceramic to the band-shaped portion. Item 3. The receiver according to item 1 or 2.

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