JPH0112468Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a vibration detection microphone that is used in contact with the cheek, mastoid region of the temporal region, etc., and is used in various communications equipment, audio equipment, etc. used for.

[Conventional technology]

Hands-free voice control type transceivers are used for conversations between multiple people located far apart at construction sites, workplaces, group activities at schools, etc., and foreign language learning devices are used to A handset with a headphone and a microphone attached to a headband is used to communicate between a specific learner and a teacher through a child's device.

As shown in FIG. 5, such a handset has an interactive microphone c attached to one end of the headband a via an arm b, and a headphone (not shown) attached to the other end. A headphone is placed in front of the person's mouth and outputs the sound from the person on the other end of the conversation, and is used with one ear covered.

However, in such a handset, all external noises existing in the external environment are input together with the voice generated from the mouth to the microphone c, so it is difficult for the side receiving the voice input to hear the voice input mixed with noise. You will hear the audio.

For this reason, for example, at a work site where industrial machinery, civil engineering machinery, etc. are in operation, the above-mentioned handset has the drawback that it cannot function satisfactorily for business-related conversations.
Furthermore, even if such a handset is attached to a motorcycle rider, at speeds of 30 km/h or higher, wind noise will significantly interfere with the conversation, making it impossible to speak, and even at high-rise construction sites, at wind speeds of 8 m/h or higher, it may be difficult to communicate. It has been confirmed that this occurs.

On the other hand, in response to this, earplug-type bone conduction microphones that are inserted into the external ear canal have been provided.

The bone conduction microphone transmits bone vibrations to a piezoelectric element through an encapsulating body having an inserter that receives sound vibrations in the ear canal, and polarizes the piezoelectric element via a lead wire in response to the generation of strain caused by the vibrations. A voltage is obtained, this voltage is reproduced as sound via an amplifier, etc., the necessary sound quality correction is performed, and the sound is output to earphones or headphones for listening.

Therefore, external noise is not directly input to this bone conduction microphone together with the audio signal. However, when an earplug-type bone conduction microphone like the one above is assembled into a handset together with a headphone like the one above, the headphone and bone conduction microphone end up blocking the left and right ear holes, respectively. When used in a field, etc., external sounds and other noise from on-site work cannot directly enter the ears, which is extremely dangerous. Furthermore, if a bone conduction microphone is used for a long period of time, the user may feel pain in the ear canal, causing various hygiene problems.

In contrast, it is placed in contact with the temporal mastoid process behind the ear or the lower edge of the temporal bone without blocking the ear, and only clear sounds are converted into sound without being bothered by external sounds or noise. A bone conduction microphone that can be used is also provided (see Utility Model Application No. 59-31885).

The bone conduction type microphone 6 is as shown in FIG. In the figure, reference numeral 8 denotes a synthetic resin housing having a U-shaped cross section, and a flexible diaphragm 9 is stretched over one open end of the housing 8 to close it. At the center of the inside of the flexible diaphragm 9, there is a piezoelectric element 10 whose crystal undergoes distortion when subjected to vibration.
is installed. Reference numeral 11 denotes a lead wire that is polarized by the above distortion of the piezoelectric element 10 and takes out the polarized voltage generated between the diaphragm 9 and the piezoelectric element 10 to the outside via a resistor or other impedance conversion element. Reference numeral 12 denotes a sensing projection protruding from the outside of the central portion of the diaphragm 9. Furthermore, the housing 8 is attached to the headband 5 side with screws 13.

In such a bone conduction microphone 6, sound vibrations transmitted to the mastoid process at the time of generation are transmitted to the piezoelectric element 10 via the acoustic diaphragm 9, causing crystal strain in the piezoelectric element 10, and creating a gap between the vibration plate 9 and the piezoelectric element 10. A polarization voltage is generated, and a change in this polarization voltage can be extracted to the outside as a change in an audio signal. Then, this audio signal undergoes necessary sound quality correction and is output to an external headphone or the like so that it can be listened to.

[Problem that the invention attempts to solve]

However, in such a conventional bone conduction microphone, as shown in FIG. 6, the end of the sensing protrusion 12 is attached to the center of a small acoustic diaphragm 9 whose periphery is fixed. The sound propagation characteristics, which are determined by the materials and weight of the small acoustic diaphragm 9 and the housing 8, deteriorate significantly in the low and high audible frequencies, and are therefore affected by external noise. When receiving a signal, there was a problem in that the voice became unclear due to a decrease in the S/N ratio. Also, if there is a design change in the material or weight of the housing, if the acoustic diaphragm used before the design change is used,
There was a problem that the frequency characteristics of sound propagation changed.

Of course, in order to improve the frequency characteristics of sound propagation in the low and high ranges, it would be better to make the acoustic diaphragm larger, but the shape of the microphone becomes larger and it is not suitable for contacting the cheek area etc. There was a problem in that it was not possible to make it into a certain size and shape.

[Means for solving problems]

In order to solve the above problems, the present invention fixes both ends of a curved flexible diaphragm to the opening of the housing, and the outer surface of the flexible diaphragm is in contact with the human body. The vibration sensing plate is provided with a sensing protrusion, and a piezoelectric element is attached to the inner surface of the flexible diaphragm, so that the necessary frequency for sound propagation can be arbitrarily and freely set.

[Effect]

In this invention, by making the flexible diaphragm installed in the opening of the housing into a curved shape, the actual length per predetermined occupied space can be made arbitrary and sufficient, and the frequency characteristics of sound propagation can be adjusted to low and high frequency regions. This has the effect of making it possible to transmit clear audio with suppressed noise.

〔Example〕

1 and 2 show an embodiment of the vibration detection type microphone of the present invention. In the same figure, 21
is a highly rigid cylindrical casing made of synthetic resin or metal molding, and both ends of a flexible diaphragm 22 are held on the inner periphery of one opening end of the casing. For this holding, any means among fitting, adhesion, and other fastening means may be selectively used.

The flexible diaphragm 22 has a winding shape, for example, an inverted S-shape (or a simple S-shape) as shown in FIG. 4A, and its total length is set to ₁ . This can be obtained by punching a metal plate with high vibration transmission sensitivity.

Reference numeral 23 denotes a drip-proof cover that seals the open end of the housing 21 to prevent sweat and raindrops from entering the housing 21, and its peripheral portion fits into the outer surface of the housing 21.

Reference numeral 24 denotes a vibration sensing plate that comes into contact with the cheeks and the mastoid part of the temporal region, and two sensing protrusions 25 protruding from the inside thereof at a certain distance apart penetrate through the drip-proof cover 23. , and is further fixed through two mounting holes 26 of the flexible diaphragm 22. In other words, the vibration sensing plate 24 is supported by the flexible diaphragm 22 at two points.

27 is a flexible diaphragm 2 between two sensing protrusions 25
This is a piezoelectric element that is attached by pasting it on the inner surface of 2.

Reference numeral 28 denotes an electronic circuit board installed in the center of the housing 21. Electronic circuit components 29 mounted on the electronic circuit board 28 include resistors, impedance conversion elements, etc., and are connected to the piezoelectric element 27 by lead wires 30. ing.

31 is a lead wire that leads the impedance-converted signal voltage to the outside.

A cover plate 32 closes the opening at the other end of the housing 21, and prevents the electronic circuit component 29 and piezoelectric element 27 from being damaged by direct mechanical external force.

Reference numeral 33 denotes a rubber cover that collectively covers the outer periphery of the casing 21, the outer periphery of the drip-proof cover 23, the outer surface of the cover plate 32, and the vicinity of the casing attachment part of the external lead wire 31. This effectively prevents noise such as vibration, the sound of hair or clothing contacting the headband or external lead wire 31, or wind noise from propagating to the housing 21.

Reference numeral 34 denotes a Magic Fastener (registered trademark) attached to the side surface of the rubber cover 33, so that it can be detachably engaged with another Magic Fastener (registered trademark) attached to the arm at the end of the headband or the inside of a motorcycle rider's helmet. It's getting old.

FIG. 3 shows how such a vibration detection type microphone d is used. This has a microphone d attached to one end of a headband a via an arm b, and the microphone d is used as a cheek-contact type microphone that lightly presses against the cheek part of the user's face. In this case, arm b is short as a whole and bent into a dogleg shape. In addition,
A headphone (not shown) is attached to the other end of the headband a.

Further, FIGS. 7 to 9 show other usage situations of the vibration detection microphone d of the present invention.

FIG. 7 shows the device used in a telephone handset 41, which has a main body 42 with a speaker section 43 at one end and a vibration detection microphone d of the present invention at the other end. ing. The main body 42 is moderately curved, and when the speaker part 43 is brought into contact with the ear part, the vibration detection microphone d
is pressed against the cheek.

FIG. 8 shows a transceiver 44 used, which includes a main body 45, an antenna 46, a panel section 47, and a transmit/receive switch 4.
8, a speaker section 49, and a vibration detection type microphone d of the present invention. The front surface 50 of the main body 45 is moderately curved, and the speaker section 49
and a vibration detection microphone d are brought into contact with or pressed against the ear and cheek, respectively.

FIG. 9 shows a hand microphone 51 used for a radio device, and the hand microphone 51 for a radio device is equipped with an ordinary microphone 52 for detecting air vibrations of voice.
A vibration detection microphone d of the present invention is also provided. 53 is a transmission/reception changeover switch, and 54 is a microphone changeover switch. When there is noise in the surroundings, the noise can be reduced by pressing the vibration detection microphone d against the cheek or the like, and when there is no noise in the surroundings, the microphone changeover switch 54 can be switched to use the normal microphone. If 52 is used, transmission with particularly good sound quality can be achieved.

When the vibration detection microphone d having the above configuration is used in contact with the cheeks as described above, the air vibrations generated in the throat and oral cavity are directly transmitted to the cheeks. The vibration immediately propagates to the vibration sensing plate 24 in contact with the external surface, and further propagates to the flexible diaphragm 22 via the sensing projections 25. This flexible diaphragm 22 has a piezoelectric element 27
Since the piezoelectric element 27 is provided with this vibration, the piezoelectric element 27 is subjected to this vibration, and a polarization voltage is generated between the piezoelectric element 27 and the flexible diaphragm 22. Therefore,
After the polarization voltage is impedance-converted, it is taken out via the external lead wire 31, subjected to necessary processing, and then sent out.

By the way, the flexible diaphragm 22 is shown in FIG.
As shown in , this length, that is, the length ₁ of the dashed-dotted line passing through its center, is the part that contributes to vibration propagation. This length ₁ is approximately equal to the length _{2 of} the linear flexible diaphragm 40 shown in _FIG . A resonant frequency equal to the frequency can be obtained. In other words, even if the flexible diaphragm 22 has an undulating shape, it is possible to obtain a resonant frequency corresponding to its entire length. Therefore, when selecting a resonant frequency arbitrarily and trying to emphasize only the sound of a predetermined frequency or cutting out noise of a predetermined frequency, the selection of the resonant frequency is facilitated by selecting its length. If it is necessary to increase the length, the above selection can be made easily by making the shape undulating, without enlarging the occupied space. As a result, the shape is convenient for contacting the cheek and temporal mastoid process.
It is possible to configure a vibration detection microphone of any size.

Note that the resonant frequency of the flexible diaphragm 22 is expressed by the following formula: is required. Here α is the reference constant, is the length,
t is the thickness, E is Young's modulus, ρ is the density of the material, √
E/ρ is vibration propagation velocity (m/sec), and π is pi.

Therefore, the resonant frequency is greatly influenced by the material and thickness of the flexible diaphragm 22, as well as its length, and by selecting this length, a signal in the required audio frequency range can be selected. You can take it out. Here, it goes without saying that the resonant frequency of the entire microphone is affected by the weight and size of the housing 21 and the like.

Note that the vibration detection microphone d can be used as a bone conduction microphone. In this case, bone conduction in the outer ear is used, so the air vibrations of the voice in the throat and oral cavity are propagated in a complex manner through the flesh, numerous bones, cartilage, etc., so the high-pitched sounds necessary for conversation are fall somewhat. On the other hand, when used as a cheek-contact type microphone, since the sound passes only through the flesh part, attenuation in the high-pitched sound part is relatively small, making it possible to transmit sound with high clarity.

[Effect of idea]

According to the present invention, the flexible diaphragm has a meandering shape with sufficient substantial length, and can be arranged all together in a narrow area. The selection and setting of the resonant frequencies of the flexible diaphragm and the microphone are optional, making it possible to propagate and reproduce clear sound without being affected by external noise.

In addition, since the flexible diaphragm that enables such excellent sound propagation and reproduction occupies a small space, it can be configured as a microphone with a size and shape suitable for the cheek and temporal mastoid regions of the human body. becomes.

In addition, if the sensing protrusions of the vibration sensing plate are fixed to such a flexible diaphragm at two or more points, stress concentration on the flexible diaphragm due to external force on the vibration sensing plate can be prevented. It is possible to effectively prevent damage to the attached piezoelectric element.

Furthermore, by covering almost the entire microphone with the rubber cover, it is possible to effectively suppress noise transmitted from the headband or the like from propagating to the piezoelectric element.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view of the vibration detection microphone of the present invention, Fig. 2 is a plan view thereof, Fig. 3 is a diagram of its use, and Figs. 4 a and b show the dimensional relationship of the flexible diaphragm. FIG. 5 is an explanatory diagram showing how a conventional microphone is used; FIG. 6 is a sectional view of a conventional bone conduction microphone; FIG. 7 is a diagram showing another usage state of the vibration detection microphone of the present invention; 8 is another usage state diagram, and FIG. 9 is a still another usage state diagram. 21... Housing, 22... Flexible diaphragm, 24...
... Vibration sensing plate, 25 ... Sensing protrusion, 27 ... Piezoelectric element, 33 ... Rubber cover.

Claims (1)

[Claims for Utility Model Registration] (1) Both ends of a curved flexible diaphragm are fixed to the opening of the housing, and the outer surface of the flexible diaphragm is in contact with the human body. A vibration detection microphone characterized in that a sensing protrusion of a vibration sensing plate is attached, and a piezoelectric element is attached to the inner surface of the flexible diaphragm. (2) The vibration detection microphone according to claim 1, wherein the flexible diaphragm has a substantially inverted S-shape or a curved S-shape. (3) The vibration according to claim 1, wherein the flexible diaphragm and the vibration sensing plate are configured in a shape and size such that they come into contact with the cheek or temporal mastoid of the human body. Detection microphone.