JPS5880997A - bone conduction microphone - Google Patents

Abstract

PURPOSE:To perform comfortable duplex transmission and reception by holding a couple of oscillating pickup elements which have nearly equal characteristics at distance in parallel to an earplug axis in such a way that their maximum sensivity directions are coincident with each other. CONSTITUTION:At a rearwise position in a earplug 1, a holding member 6 is fixed to hold a couple of oscillating pickup elements 7 and 8. Those elements 7 and 8 are so adjusted that their characterisitcs are nearly equal while held at distance in such a way that their maximum sensivity directions are coincident with each other without any mutual influence. At the center part between these elements 7 and 8, a sound path pipe 22 is fixed in the axis direction of the earplug 1 and a sound passage 24 is formed in the pipe 22. In this constitution, when oscillation is conducted to the elements 7 and 8, outputs having equal amplitude appears at output terminals 11 and 12, and 13 and 14 of the elements 7 and 8. Sound pressure from a handset 23, on the other hand, is listened through a conduction path 24, but the unnecessary outputs are in the opposite direction to the elements 7 and 8, so that they are balanced and canceled.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bone conduction microphone that is capable of transmitting a transmitted voice and listening to a received voice and a signal tone using one ear.

Conventionally, when a bone conduction microphone in which a vibration pickup element for picking up a bone conduction sound signal is supported in a cantilevered manner is used for listening to incoming speech, for example, Utility Model Application No. 56-127489
As described in Japanese Utility Model Publication No. 156-142091, a sound conduction path for introducing the receiving sound pressure is provided on the outer periphery of the earplug, or a sound conduction path is provided at the base of the earplug as described in, for example, Japanese Utility Model Application Publication No. 156-142091. A method is adopted in which a sound guide hole is formed and the received sound is guided along the outer circumferential surface of the earplug.

However, in the former method, since both the sound conduction path and the vibration pickup element are one piece, the vibration pickup element receives vibrations due to the received sound pressure from the sound conduction path, and the received voice is transmitted to the bone conduction microphone. This method has the disadvantage that it does not cause leakage and cannot reliably transmit bone conduction audio signals.

On the other hand, in the latter method, since the sound guide holes are provided radially, it is possible to reduce the sound pressure against the vibration pickup element, but depending on how the earplug is attached to the ear canal, the sound guide path may be blocked. However, there was a problem that the incoming call could not be heard reliably. .

To provide a bone conduction micropon which reduces the leakage pressure of received voice as much as possible, prevents blockage of a sound conduction path, and enables comfortable simultaneous transmission and reception.

Hereinafter, the present invention will be explained in detail based on examples thereof. As shown in FIGS. 1 and 2, the earplug 1 has a sound emitting port 3 formed at the front end of a cylindrical external auditory canal insertion part 2, and a brim-shaped part formed at the rear side of the external auditory canal insertion part 2. A lid 6 is provided at the rear end of the brim 4. A holding member 6 is fixed at a rearward position inside the earplug 1, and a pair of vibration pickup elements 7, 8 are held on this holding member 6.

Each vibration pickup element 7, 8 has output terminals 11, 12 and 13, 14 on both sides of the ceramic piezoelectric elements 9 and 1o, for example. Weights 16 and 1i for adjusting sensitivity and frequency characteristics are provided at the tip, and both are adjusted so that the characteristics are approximately equal. Both vibration pickup elements 7 and 8 have their maximum sensitivity directions in the same direction, and 17 and 18 are held in a cantilever manner by the holding member 6 and coupled to the earplug 1 so as not to influence each other. The output terminals 11, 12 and 1a14 of each of the vibration pickup elements 7, 8 are connected to an amplifying section 19, where the amplified and synthesized products are amplified by a preset magnification, and are led out to the outside through an output cord 20. or directly,
The output code 20 is derived and transmitted. One end of a sound conducting pipe 22 is fixed to the lid 6y holding member 6 of the earplug 1 so as to be inserted therethrough in the axial direction of the earplug 1 at the center between both the vibration pickup elements 7 and 8. The other end of the sound guide pipe 22 is acoustically coupled to a receiver (for example, an earphone) 23, and a sound guide path 24 is formed within the sound guide pipe 22 for introducing received voice and signal sound into the ear canal.

The output terminal 25 of the output cord 2o and the input terminal 27 of the input cord 26 connected to the receiver 23 are connected to the receiving section and the transmitting section of a main communication device, such as a wireless transceiver, a wired telephone, or other voice communication device. The output cord 2o may be disposed not shown in the illustrated example and drawn out to the outside near the communication device, or may be integrated on the outside of the sound guide pipe 22.

The amplifying section 19 of the vibration pickup elements 7 and 8 will be explained. FIG. 3 shows an example, in which each output terminal 11, 12, 13t 1 of the vibration pickup elements 7, 8
4 is the amplifier 19a.

The output side of the amplifier 191L, 1''9b is connected to both ends of the variable resistor 32, and the output is taken from the midpoint 33 and ground 34. Further, FIG. 4 shows another example, in which each output terminal 11, 12, 13 of the vibration pickup element 7.8
, 14 are connected to the input terminals 28 to 31 of the amplifying section 19, and the output is taken out from the midpoint 33, amplified by one amplifier 190, and outputted to the terminals 36. The signal is output from the ground 34 to the outside.

Next, the operation of this embodiment will be explained. In this bone conduction microphone, when vibration is applied to the vibration pickup element 7.degree.6 base 28 in the direction of the arrow in FIG. 2, the vibration is transmitted to the vibration pickup elements 7 and 8 via the earplug 1 and the holding member 6. At this time, as described above, both vibration pickup elements 7
, 8 are adjusted so that their sensitivity characteristics and frequency characteristics are approximately equal, so that outputs of equal amplitude appear at output terminals 11, 12 and 13, 14 of each vibration pickup element 7 and 8. Letting this output be El and Jc2, x1=x2. On the other hand, the sound pressure due to the voice or signal from the receiver 23 is heard through the sound conduction path 24, through the sound emitting port 3 of the earplug 1, and by changing the sound pressure in the ear canal. Unnecessary output Δ due to this sound pressure
x4. Δx2 is applied to each vibration pickup element 7, 8, but these unnecessary outputs ΔR1, ΔN2 are in opposite directions to the two vibration pickup elements 7.8. If ΔN1 is (→, then Δ!2 is (→) At this time, since the sound conduction path 24 is located at the center between both vibration pickup elements 7 and 8 as described above, both unnecessary outputs Δ1c1 and Δtou2 are equal and can be balanced and canceled out.

Therefore, the bone conduction audio signal is converted into the output current of the vibration pickup element 7 and 8 without being affected by the received voice or the sound pressure caused by the signal, and this is amplified by the amplifier 19 and transmitted. be able to.

Further, in this embodiment, the amplifier section 19 includes a flexible resistor 32.
Since this midpoint 33 is set as Δx1−Δx2:0
Adjust variably so that As a result, the output of vibration pickup element 7#8, force IE, ·E2 becomes "t412 torque fsE, (1, + 12) >> (1E1-
It does not affect transmission unless it is an IEd. In this way, the variable resistor a2 and each vibration pickup element 7
, 8, unnecessary output Δx1. By variably adjusting Δ1c2, the vibration pickup element 7°8 and the sound conduction path 24
Even if the accuracy of the relative position, mounting direction, sensitivity difference, etc. is reduced, unnecessary outputs to both vibration pickup elements 7 and 8 can be balanced and transmitted.

FIG. 6 shows another embodiment of the invention. In the above example, both vibration pickup elements 7 and 8 are arranged so that their maximum sensitivity directions are opposite to each other with the sound conduction path 24 in between. In other words, both vibration pickup elements 7
．． 8 are arranged in parallel with the sound conduction path 24 in between, even though their maximum sensitivity directions are in the same direction.
The other configurations are the same as those of the previous embodiment.

In the embodiment described above, the tip of the sound guide pipe 22 is positioned near the base holding portions of the vibration pickup elements 7 and 8, but it is extended to the sound emitting port 3 of the earplug 1. May be combined with In addition, since the unnecessary output acting on the vibration pickup elements 7 and 8 increases outside the communication band and may interfere with communication, either a low-pass filter or a high-pass filter is used to reduce the output of the vibration pickup elements 7 and 8. , or both may be used for removal.

Furthermore, when two amplifiers are used, the gain of at least one of them may be adjusted to combine the outputs of the vibration pickup elements to cancel out unnecessary reception sound pressure. Alternatively, it can also be configured with - operational amplifiers. Furthermore, if the knob of the variable resistor 24 is provided on page 69 of the lid of the earplug 1, adjustment can be facilitated.

As is clear from the above description, according to the present invention, a pair of vibration pickup elements having substantially the same characteristics are spaced apart from each other so that their maximum sensitivity directions are in the same direction, and are inserted into the earplug parallel to the earplug axis. A sound conduction path is provided in the center between both vibration pickup elements. Therefore, it is possible to reduce the receiving sound pressure leaking to the vibration pickup element in a balanced manner, it is also possible to prevent the receiving passageway from being blocked by the ear canal, and there is an advantage that comfortable simultaneous transmission and reception can be performed.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a bone conduction microphone according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the ■-■ arrow in FIG. 1, and FIGS. 3 and 4 are circuit diagrams of the amplifier section, respectively. FIG. 6 is a sectional view of another embodiment of the invention. 1...Earplugs, γ, 8...Vibration pickup element, 19...Amplification section, 2o...
Output code, °23... Handset, 24...
...Sound conduction path. Figure 1 Figure 2 it z

Claims (1)

[Claims] An earplug having a sound emitting port and an external insertion portion, and a bone conduction sound signal that is held parallel to the earplug axis and spaced apart from each other so that the maximum sensitivity direction is in the same direction inside the earplug. A pair of vibration pickup elements having substantially the same detection characteristics, a transmission means for transmitting the outputs of these vibration pickup elements, and a sound guide provided in the center between the two vibration pickup elements and acoustically coupled to the receiver. A bone conduction microphone characterized by comprising a passageway.