JP3876061B2 - Voice pickup device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an audio pickup apparatus provided with a housing that accommodates a piezoelectric element in a state in which the piezoelectric element is supported in a freely oscillating manner, and amplification means that amplifies a detection signal of the piezoelectric element with a set amplification factor.
[0002]
[Prior art]
Such a sound pickup device is a device that detects sound by mechanical vibration caused by sound being transmitted to the housing, the vibration of the piezoelectric element in the housing due to the vibration, and converting the mechanical vibration into an electrical signal, It is used for voice detection in communication devices such as mobile phones and transceivers.
Conventionally, this type of audio pickup device is a so-called bone-conducting system in which a housing supporting a piezoelectric element is brought into contact with or near a human ear and the bones of the head are vibrated by the vibration of the human vocal cord. Commonly used for speech detection. Since such mechanical vibration is generally weak, the detection signal of the piezoelectric element is amplified by the amplifying means.
By detecting the bone conduction voice in this way, the voice can be detected in a state in which the influence of ambient noise is sufficiently suppressed.
[0003]
[Problems to be solved by the invention]
However, in the above conventional configuration, since conditions are generally set for detecting bone conduction speech, even if the surrounding speech has a certain value as information and it is desired to detect speech conducted by air. It was difficult to detect accurately.
The present invention has been made in view of the above circumstances, and an object thereof is to provide an audio pickup device capable of accurately detecting not only bone conduction audio but also audio conducted by air.
[0004]
[Means for Solving the Problems]
By providing the configuration according to claim 1, the sound detection state detecting means for detecting the state of the piezoelectric element detects the bone conduction sound in which the state of the piezoelectric element is transmitted to the housing in contact with the human body. Detects whether it is in a detection state or an air conduction sound detection state that detects air conduction sound transmitted to the housing via air, and amplifies the detection signal of the piezoelectric element with a set amplification factor based on the detection information The amplifying means that makes the set amplification rate different between the bone conduction sound detection state and the air conduction sound detection state. That is, in the bone conduction sound detection state and the air conduction sound detection state, the signal detection level of the piezoelectric element is different, and if it is amplified and output as it is with a common set amplification factor, it is practically used in at least one state. There is a possibility that a signal of a level cannot be obtained, but by setting the set amplification factor to be different between the bone conduction sound detection state and the air conduction sound detection state as described above, the set amplification factor can be changed. The signal detected by the piezoelectric element can be set to an appropriate signal level even in the bone conduction sound detection state or the air conduction sound detection state. Can be output. Thus, it has become possible to provide an audio pickup device that can accurately detect not only bone conduction audio but also audio conducted by air.
[0005]
Further, by providing the configuration according to claim 2, a state in which mechanical vibration is transmitted between a housing that supports the piezoelectric element and a housing that holds the housing, and a state in which transmission of the mechanical vibration is suppressed. And can be switched. Therefore, in the bone conduction sound detection state in which the bone conduction sound transmitted to the housing that is in contact with the human body is detected, even if the housing vibrates due to ambient noise as a state in which transmission of mechanical vibration is suppressed, Vibration can be suppressed from being detected by the piezoelectric element and become noise. On the other hand, in the air conduction sound detection state, when the housing vibrates by surrounding sound as a state of transmitting mechanical vibration, the vibration is transmitted to the housing. In addition, the piezoelectric element is caused to vibrate by being transmitted to the piezoelectric element, and the piezoelectric element detects not only the component that vibrates the housing directly by sound conducted by air but also the vibration of the housing holding the housing. The surrounding voice can be detected efficiently.
[0006]
Further, by providing the configuration of the fourth aspect, the housing for supporting the piezoelectric element is pressed against the part of the human body in order to detect the bone conduction human voice, by the force that is the pressing, the housing However, it shifts from a position where it abuts on the housing and transmits mechanical vibration to a position where it is separated from the housing and suppresses transmission of mechanical vibration. When the housing is separated from the human body, the housing returns to a position where the housing comes into contact with the housing and transmits mechanical vibration by the return biasing force of the elastic member, and detects the sound transmitted by the air. It is a suitable position. In other words, it is usually in a state suitable for detecting sound transmitted by air, and when detecting human bone conduction sound, it is suitable for detecting bone conduction sound using the operating force for that purpose. As a result, both sound conducted by air and bone conduction sound can be accurately detected by a simple operation.
[0007]
In addition, by providing the configuration according to the fifth aspect, the elastic member that urges the housing that supports the piezoelectric element back to the position where it abuts the housing has viscoelasticity. Therefore, mechanical vibration transmitted to the housing through the elastic member can be effectively absorbed, and the piezoelectric element can be suppressed from detecting noise as much as possible when the housing is at a position away from the housing.
[0008]
Further, by providing the above-described structure according to claim 6, wherein, when the housing which supports the piezoelectric element is pressed against the part of the human body in order to detect the bone conduction human voice, by the force that is the pressing, the housing Is in the bone conduction sound detection state by using a displacement from a position where the mechanical vibration is transmitted in contact with the casing to a position where the transmission of the mechanical vibration is suppressed away from the casing. Alternatively, it is detected whether the air conduction voice is detected. That is, a switch including an operated piece returned to the protruding side is arranged so that the operated piece is pushed to the retract side by the displacement of the housing to a position away from the housing. I will leave it. Therefore, the detection of whether it is in the bone conduction sound detection state or the air conduction sound detection state can be performed simply by providing a switch by utilizing the operation force when detecting human bone conduction sound. It can be done with a simple configuration.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a case where a voice pickup device according to the present invention is provided in a mobile phone will be described below with reference to the drawings.
As shown in FIGS. 1 and 2, the audio pickup device VP sets and amplifies a substantially rod-shaped piezoelectric element 1, a housing 2 that accommodates the piezoelectric element 1 in a state where the piezoelectric element 1 is oscillated, and a detection signal of the piezoelectric element 1. As shown in FIG. 3, the housing 2 is held by the housing 3 of the mobile phone PP with the surface thereof exposed.
[0010]
The support structure of the piezoelectric element 1 in the housing 2, the signal processing circuit of the piezoelectric element 1, and the like will be described in detail.
The piezoelectric element 1 is a so-called bimorph type in which a metal plate is sandwiched between two piezoelectric ceramic elements and is bonded to improve detection sensitivity.
The piezoelectric element 1 has one longitudinal end thereof firmly fixed and held on the circuit board 4 by soldering, and the circuit board 4 receives the detection signal of the piezoelectric element 1 and mainly performs impedance conversion. And other capacitors are arranged. The circuit board 4 is fixed to the bottom surface of the shield case 6 fixed to the inner wall of the housing 2, and the mechanical vibration of the housing 2 is accurately transmitted to the piezoelectric element 1 so that the piezoelectric element 1 is vibrated efficiently. Yes. The shield case 6 covers the entire circuit board 4 and electromagnetically shields it, and contributes to an improvement in the S / N ratio of the detection signal of the piezoelectric element 1. The housing 2 also functions as a protective case for the piezoelectric element 1 and the like.
[0011]
The detection signal of the piezoelectric element 1 after impedance conversion or the like by the FET 5 is input to the amplifying means AP shown in FIG.
The amplification means AP includes two amplifiers 7a and 7b having different amplification factors, and outputs from the two amplifiers 7a and 7b are input to the switching circuit 8.
The switching circuit 8 is a circuit that selectively outputs one of the output signals of the two amplifiers 7a and 7b based on the on / off state of a switch 9 described later.
The output signal of the switching circuit 8 is input to an output suppression circuit 10 that suppresses an excessive input signal to a signal level within a set range, and the output signal of the output suppression circuit 10 is input to the signal processing circuit of the mobile phone PP. .
[0012]
Next, a configuration for holding the housing 2 in the housing 3 will be described.
As shown in FIG. 1, the housing 2 protrudes from an opening formed in the housing 3 and has a base plate 11 and a viscoelastic member 12 fixed to the housing 3. The two flange portions 2 a are held by the housing 3 in a state of being pressed against the inner wall of the housing 3. The viscoelastic member 12 is a member having viscoelasticity such as a rubber material or vinyl chloride, and urges the housing 2 to return to the outer side of the housing 3 and absorbs mechanical vibration transmitted to the housing 2.
Therefore, the housing 2 is urged to return to a position where it abuts against the housing 3, specifically, the inner wall of the housing 3, by the viscoelastic member 12 functioning as the elastic member SP, and as will be described later, When the housing 2 is pressed toward the inside of the housing 3 by a force pressed partially, the housing 2 is displaced to a position away from the housing 3 as shown in FIG.
When the housing 2 is located at a position where it abuts against the inner wall of the housing 3, the housing 2 and the housing 3 are in a state of transmitting mechanical vibration, and the housing 2 is located at a position away from the housing 3. When positioned, the housing 2 and the housing 3 are in a state in which transmission of mechanical vibration is suppressed, so that the housing 2 and the housing 3 holding the housing 2 transmit mechanical vibration. It is possible to switch between a state and a state where transmission is suppressed.
[0013]
The base plate 11 that supports the viscoelastic member 12 is positioned adjacent to the viscoelastic member 12 so that the housing 2 is in contact with the housing 3 or is separated from the housing 3. A switch 9 is provided for detecting whether or not the operation is being performed. The switch 9 is provided with an operated piece 9a that is urged to return to the protruding side, and the switch 9 is arranged so that the retracting direction of the operated piece 9a coincides with the displacement direction of the housing 2.
As the housing 2 is displaced from the inner wall of the housing 3 to a position away from the inside of the housing, the bottom surface side of the housing 2 pushes the operated piece 9a and moves it to the retraction side. The on / off state of the switch 9 is changed by the movement of the operated piece 9a toward the retraction side.
Therefore, the switch 9 detects whether the piezoelectric element 1 is in a bone conduction sound detection state for detecting human bone conduction sound or in an air conduction sound detection state for detecting sound conducted by air. Function as the sound detection state detection means VS to detect the state where the housing 2 is located at a position where it abuts the housing 3 as the air conduction sound detection state and is located at a position away from the housing 3 Is detected as a bone conduction voice detection state.
[0014]
Next, the operation of the cellular phone PP provided with the voice pickup device VP having the above-described configuration will be schematically described by exemplifying a case where a call is made to the other party of the call.
When a user of the mobile phone PP makes a call to the other party, the telephone number input button or the like (not shown) is operated with the swinging-type opening / closing lid 14 attached to the housing 3 opened. The call state is changed later. In a call state, with the open / close lid 14 closed as necessary, the speaker 15 of the mobile phone PP is put on the ear to have a conversation with the other party.
At this time, the user presses the housing 2 held by the housing 3 against the face near the ear as a part of the human body. Due to the pressing force generated by this operation, the housing 2 is displaced inward of the housing 3, and the bone conduction voice detection state is obtained.
[0015]
In this bone conduction sound detection state, as described above, the housing 2 is separated from the housing 3, and the mechanical vibration of the housing 3 is suppressed from being transmitted to the housing, and the bone conduction sound transmitted to the vicinity of the user's ear is transmitted. Since the piezoelectric element 1 can be accurately detected by being converted into an electrical signal, a good conversation with little influence of ambient noise can be performed.
When the switch 9 detects that this bone conduction voice detection state is detected, this detection information is input to the switching circuit 8 shown in FIG. 2, and the switching circuit 8 includes two amplifiers for amplifying the detection signal of the piezoelectric element 1. The output of one amplifier 7a out of 7a and 7b is selected and output to the output suppression circuit 10 and transmitted to the other party of the call through the other processing circuit. The amplification factor of the amplifier 7a is set to a value suitable for detecting bone conduction sound.
[0016]
On the other hand, when the user of the mobile phone PP wants to actively transmit not only the user's voice but also the surrounding voice to the other party of the call, or when the ambient noise is sufficiently low, A conversation is held with the speaker 15 placed on the ear and the housing 2 housing the piezoelectric element 1 not touching the face. In this way, the housing 2 maintains a state in which the inner wall of the housing 3 abuts, and when ambient sound including the user's sound is conducted by the air to vibrate the housing 3, the vibration is transmitted to the housing 3. It is transmitted to 2. That is, the housing 2 not only directly vibrates due to the user's voice or the like, but also vibrates due to mechanical vibration transmitted from the housing 3, and both contribute to the vibration of the piezoelectric element 1. Accordingly, the entire housing 3 contributes to the sound detection.
[0017]
When the switch 9 detects that the air conduction sound detection state for detecting the sound transmitted by the air is detected, this detection information is input to the switching circuit 8 shown in FIG. 2, and the amplifier of the two amplifiers 7a and 7b. The output of 7b is selected and output to the output suppression circuit 10 and transmitted to the other party of the call through another processing circuit. The amplification factor of the amplifier 7b is set to a value suitable for detection of sound conducted by air as described above, and the magnitude relationship with the set amplification factor of the other amplifier 7a is the size of the casing 3. It will change depending on the relationship with the others.
[0018]
[Another embodiment]
Hereinafter, other embodiments are listed.
(1) In the above embodiment, the case where the voice pickup device VP of the present invention is provided in the cellular phone PP is exemplified, but it is used for various recording devices such as transceivers as well as various recording devices. Can do.
(2) In the above embodiment, the housing 2 that supports the piezoelectric element 1 and the housing 3 that holds the housing 2 are configured to be switchable between a state of transmitting mechanical vibration and a state of suppressing transmission. However, the mechanical vibration of the housing 3 is always transmitted to the housing 2 so that it is always in one of the states, that is, the housing 2 is integrally formed with the housing 3, for example. Or you may make it suppress the mechanical vibration of the housing | casing 3 being always transmitted to a housing, for example by making the housing 2 support the viscoelastic member attached to the housing | casing 3. FIG.
[0019]
(3) In the above embodiment, the amplifying means AP includes two amplifiers 7a and 7b having different set amplification factors, and the bone conduction voice detection is performed by selectively switching which amplifier signal is output. Although the set amplification factor is different between the state and the air conduction sound detection state, one amplifier capable of changing the amplification factor is provided, and the amplification factor is changed according to the output signal of the switch 9. The configuration for changing the set amplification factor can be variously changed.
(4) In the above embodiment, the elastic member SP for returning and urging the housing 2 to the position in contact with the housing 3 is formed by the viscoelastic member 12 having viscoelasticity as a material. A coil spring or the like may be used as the SP, and the specific configuration for returning and energizing the housing 2 can be variously changed.
[0020]
(5) In the above embodiment, the voice detection state detection means VS for detecting whether the bone conduction voice detection state or the air conduction voice detection state is provided with the switch 9. However, for example, the housing 2 is provided with a pair of electrodes in contact with the flange portion 2a of the housing 2 on the inner wall of the housing 3, and the flange 2a of the housing 2 is provided with an electrode for short-circuiting the pair of electrodes. Is in contact with the housing 3 and the pair of electrodes short-circuited is detected as the air conduction sound detection state, the housing 2 is separated from the housing 3, and the pair of electrodes are electrically insulated. It may be configured to detect the current state as the bone conduction voice detection state, and the specific configuration of the voice detection state detection means VS can be variously changed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part according to an embodiment of the present invention. FIG. 2 is a block configuration diagram according to an embodiment of the invention. FIG. 3 is an external perspective view of a mobile phone according to an embodiment of the invention. Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Piezoelectric element 2 Housing 3 Case 9 Switch 9a Operated piece AP Amplifying means SP Elastic member VS Voice detection state detecting means

Claims (6)

An audio pickup device provided with a housing for storing a piezoelectric element in a state of being supported in a freely vibrating manner, and an amplifying means for amplifying a detection signal of the piezoelectric element with a set amplification factor,
Voice detection state detection means for detecting the state of the piezoelectric element;
The sound detection state detection means is a bone conduction sound detection state in which the state of the piezoelectric element detects a bone conduction sound transmitted to the housing in contact with a human body or air conduction sound transmitted to the housing via air. Detect if the air conduction voice detection state to detect,
The amplifying unit is configured to vary the set amplification factor between the bone conduction sound detection state and the air conduction sound detection state based on detection information of the sound detection state detection unit. . Sound pickup apparatus according to claim 1, characterized in that the switching freely configured and status suppress the transmission of status and mechanical vibration for transmitting the mechanical vibrations between the housing for holding the said housing housing.   When the piezoelectric element is in the air conduction sound detection state, a state in which mechanical vibration is transmitted between the housing and the housing,
  The audio pickup device according to claim 2, wherein when the piezoelectric element is in the bone conduction audio detection state, transmission of mechanical vibration is suppressed between the housing and the housing. The housing is displaceable between a position where the housing comes into contact with the housing and is in the state of transmission, and a position where the housing is separated from the housing and enters the state of suppressing the transmission, and the housing is in contact with the housing. Supported by an elastic member so as to be biased back to the position side,
The audio pickup device according to claim 2, wherein the housing is configured to be displaced from a position in contact with the housing to a position away from the housing by a force pressed against a part of a human body. . The audio pickup device according to claim 4, wherein the elastic member is configured to have viscoelasticity. The sound detection state detection means moves to the retraction side when the operated piece returned to the protruding side is pushed by the housing that is displaced from a position in contact with the housing to a position away from the housing. The voice pickup device according to claim 4 , wherein the voice pickup device is configured by a switch that changes on and off.

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