JP2008301133A - Telephone device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication device that suppresses speaker sound that leaks out of a housing, thereby increasing the radiated sound pressure of the speaker and improving the howling prevention effect.
A module MJ of a communication device A includes a speaker SP that outputs audio information transmitted from the outside, a microphone M1, a microphone M2 disposed at a position farther than the microphone M1 with respect to the speaker SP, and a microphone M2. The sound processing unit 10 that removes the sound signal of the microphone M1 from the sound signal and transmits it to the outside is provided in the housing A1, and the sound information is output from the one surface side of the speaker SP to the outside of the housing A1, and the housing A1 The body A10 and the cover A11 are in contact with each other, and the rear air chamber Br, which is a space formed on the other surface side of the speaker SP in the housing A1, and the body A10 and the cover in the rear air chamber Br. And an elastic portion 60 pressed between the contact surfaces with A11.
[Selection] Figure 1

Description

  The present invention relates to a call device.

  Conventionally, there is a communication device installed indoors with an interphone system or the like, which includes a speaker that outputs sound from a communication device installed in another place, a microphone that inputs sound transmitted to the other communication device, and the like. Yes.

  Since howling occurs when the sound generated from the speaker wraps around the microphone, various measures for preventing howling are taken. For example, a pair of microphones, a delay circuit that delays the output of the microphone closer to the speaker by the delay time of the sound wave corresponding to the difference in distance between the two microphones and the speaker, and the difference in distance between the two microphones and the speaker A level adjustment amplifier circuit that performs level adjustment to match the output levels of both microphones with respect to the sound from the speaker, and a differential amplifier circuit that uses both microphone outputs passing through the delay circuit and the level adjustment amplifier circuit as inputs. There is a communication device that uses the output of the differential amplifier circuit as a transmission signal.

In this communication device, after picking up the sound from the speakers with a pair of microphones, the delay and level adjustment is performed, and the sound components from the speakers input to both microphones are canceled by the differential amplifier circuit. The transmitted voice can be transmitted with only the voice component removed. (For example, refer to Patent Document 1).
Japanese Patent No. 2607257 (page 2, left column, line 13 to right column, third line, page 4, right column, lines 26 to 49, FIGS. 1 and 5)

  FIG. 17 shows a configuration of a conventional communication device A ′, in which a housing A100 is configured by a body A110 having an opening on the rear surface and a cover A111 covering the opening of the body A110. The microphone SP1 for outputting sound to the outside of the housing A100, the microphone board MB ′ on which the microphones M1 ′ and M2 ′ are mounted, and the microphones M1 ′ and M2 ′ are subjected to delay and level adjustment for both microphones. A voice processing unit 10 ′ that cancels the speaker sound input to M1 ′ and M2 ′, removes only the voice component from the speaker SP ′ and transmits the transmitted voice, and includes the front surface of the housing A100 and the speaker SP ′. A front air chamber Bf ′ that is a space surrounded by the front surface side of the housing, the inner wall surface of the housing A100, and the rear surface of the speaker SP ′ Air chamber Br 'is formed after a space surrounded by the.

  In this conventional configuration, the housing A100 is composed of two parts (for example, a resin molded part) of a body A110 and a cover A111, and the body A110 and the cover A111 have a mating surface in the rear air chamber Br '. However, a gap is easily formed on the mating surface, and sound radiated from the back surface of the speaker SP 'to the rear chamber Br' leaks out of the housing A100 from the mating surface of the body A110 and the cover A111.

  Here, the phase of the sound radiated from the back surface of the speaker SP ′ to the rear air chamber Br ′ is reversed with respect to the sound radiated from the front surface of the speaker SP to the front air chamber Bf ′ (hereinafter, the speaker SP). The phase of the sound radiated from the front surface of the speaker is referred to as a positive phase, and the phase of the sound radiated from the back surface of the speaker SP is referred to as an opposite phase).

  Therefore, the phase of the antiphase sound leaking out of the housing A100 from the mating surface of the body A110 and the cover A111 is reversed from the phase of the normal phase sound radiated from the surface of the speaker SP ′. Sway forward, the positive phase sound radiated from the surface of the speaker SP ′ cancels each other, the radiated sound pressure of the speaker SP ′ decreases, and the speaker SP ′ emits sound to the speaker in front. It becomes difficult to hear.

  Further, when the sound of opposite phase leaking from the mating surface of the body A110 and the cover A111 to the outside of the housing A100 is collected by the microphones M1 ′ and M2 ′, the amount of cancellation of the speaker sound by the sound processing unit 10 ′ is reduced, The effect of preventing howling will be reduced.

  Furthermore, in the conventional example of FIG. 17, in order to improve the sound quality and efficiency of the speaker SP ′, the wall 141 is erected from the inner surface of the body A110, and the end surface of the wall 141 is brought into contact with the rear surface of the cover A111. Thus, a hollow acoustic tube 140 composed of the wall 141 and the inner surfaces of the body A110 and the cover A111 is formed in the rear air chamber Br ′, and the end surface of the wall 141 and the inner surface of the cover A111 are formed. Air leaks from the gap formed between them, and the function as an acoustic tube is reduced.

  The present invention has been made in view of the above-described reasons, and an object of the present invention is to suppress the speaker sound that leaks out of the housing, thereby increasing the radiated sound pressure of the speaker and improving the howling prevention effect. Is to provide.

  According to the first aspect of the present invention, a speaker that outputs sound information transmitted from the outside, a first microphone that collects sound and outputs a sound signal, and a position farther from the first microphone than the speaker is disposed. A second microphone that collects sound and outputs a sound signal; and a sound processing unit that removes the sound signal of the first microphone from the sound signal of the second microphone and transmits the sound signal to the outside. The sound information is output from the one surface side of the speaker to the outside of the housing, and the housing is configured by bringing a plurality of components into contact with each other, and is a space formed on the other surface side of the speaker in the housing. It is characterized by comprising a rear air chamber and an elastic part pressed between the contact surfaces of each component in the rear air chamber.

  According to this invention, by suppressing the speaker sound leaking out of the housing, it is possible to increase the radiation sound pressure of the speaker and improve the howling prevention effect.

  According to a second aspect of the present invention, in the first aspect, the elastic portion is an elastomer that attenuates the amplitude of a sound wave in a predetermined frequency band.

  According to the present invention, sound leakage from the housing can be further suppressed.

  According to a third aspect of the present invention, in the first or second aspect, the housing is configured by providing the elastic portion between the contact surfaces of the first component and the second component. Is provided with a locking hole, and the second component is provided with a locking claw that locks into the locking hole by the restoring elasticity of the pressed elastic portion.

  According to the present invention, the amount of deformation of the elastic portion can be set to a predetermined amount by appropriately setting the locking position between the locking claw and the locking hole, and the degree of sealing of the space in the housing by the elastic portion can be reduced. Can be secured.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the housing is configured by providing the elastic portion between the contact surfaces of the first component and the second component. An acoustic tube configured by abutting an end surface of a wall portion standing on the inner surface of the other component with the inner surface of one component of the second components is provided in the rear air chamber, and the elastic portion is , It is characterized by being pressed between the inner surface of one component and the end surface of a wall part.

  According to the present invention, the sound quality and efficiency of the speaker are improved by the acoustic tube even if the rear air chamber has a small capacity.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the housing is made of resin, and the elastic portion and the housing are integrally formed.

  According to this invention, the sealing degree of the space in the housing by the elastic part is further improved.

  As described above, the present invention has an effect of suppressing the speaker sound leaking out of the housing, thereby increasing the radiation sound pressure of the speaker and improving the howling prevention effect.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
The communication device A according to the present embodiment is shown in FIGS. 1 to 3, and is configured by accommodating a communication module MJ in a rectangular box-shaped device body A2 provided with a voice switch SW1. The apparatus main body A2 is formed, for example, by joining two resin molded members, and after housing the call module MJ, each joining member is joined by a fitting means or an adhesive.

  The call module MJ includes a housing A1 including a box-shaped body A10 having an opening on the rear surface and a box-shaped cover A11 having an opening on the front surface. The housing A1 includes a speaker SP, a microphone board MB1, and an audio processing unit. The unit 10 is provided. A diaphragm 23 described later of the speaker SP is disposed so as to face a plurality of sound holes 60 drilled in the front surface of the apparatus main body A2.

  As shown in FIG. 3, the audio processing unit 10 is composed of an IC including a communication unit 10a, audio switch units 10b and 10c, an amplification unit 10d, and a signal processing unit 10e, and is arranged in the housing A1. A voice signal transmitted from the communication device A installed in another room or the like through the information line Ls is received by the communication unit 10a, amplified by the amplification unit 10d through the voice switch unit 10b, and then the speaker. Output from SP. Further, by operating the call switch SW1, a call can be made and each audio signal input from the microphone M1 (first microphone) and the microphone M2 (second microphone) on the microphone board MB1 is received by the signal processing unit 10e. After being subjected to signal processing to be described later, it passes through the voice switch unit 10c, and is transmitted from the communication unit 10a to the communication device A installed in another room or the like via the information line Ls. That is, it functions as an intercom that allows two-way calls between rooms. Note that the power of the communication device A may be supplied from an outlet provided in the vicinity of the installation location or may be supplied via the information line Ls.

  The speaker SP includes a cylindrical yoke 20 that is formed of an iron-based material and has an opening at one end, and the yoke 20 has a circular support 21 extending outward from the opening end. A cylindrical permanent magnet 22 is disposed in the cylinder of the yoke 20, and the edge on the outer peripheral side of the dome-shaped diaphragm 23 is fixed to the edge surface of the support 21. A cylindrical bobbin 24 is fixed to the rear surface of the diaphragm 23, and a voice coil 25 is provided at the rear end of the bobbin 24. The bobbin 24 and the voice coil 25 are provided so that the voice coil 25 is positioned at the opening end of the yoke 20, and freely move in the front-rear direction in the vicinity of the opening end of the yoke 20. When an audio signal is input to the polyurethane copper wire of the voice coil 25, an electromagnetic force is generated in the voice coil 25 due to the current of the audio signal and the magnetic field of the permanent magnet 22, so the bobbin 24 is accompanied by the diaphragm 23. To vibrate in the front-rear direction. At this time, a sound corresponding to the audio signal is emitted from the diaphragm 23.

  And rib 11 is formed in the front inner side of body A10 which diaphragm 23 of speaker SP opposes, and the end surface of convex part 21a which protruded from the outer peripheral edge of circular support body 21 of speaker SP to the front side. In a state in which the speaker SP is in contact with the rib 11, the speaker SP is fixed in a state where the diaphragm 23 faces the front surface of the body A10 from the inside.

  When the speaker SP is fixed in the housing A1, the front air chamber Bf which is a space surrounded by the front inner side of the housing A1 and the front surface side (the diaphragm 23 side) of the speaker SP, the rear inner side and the inner side surface of the housing A1. And a rear air chamber Br which is a space surrounded by the back surface side (yoke 20 side) of the speaker SP. The front air chamber Bf communicates with the outside through a plurality of sound holes 12 provided on the front surface of the body A10. The rear air chamber Br becomes a space that is insulated (not communicated) with the front air chamber Bf because the protrusion 21a of the support 21 of the speaker SP and the rib 11 on the inner surface of the housing A1 are in close contact with each other.

  Further, as shown in FIGS. 1 and 4, the housing A <b> 1 has one end separated from the inner wall surface and the other end continuous with the inner wall surface along the inner wall surface of the body A <b> 10 surrounding the rear chamber Br on the back surface of the speaker SP. The wall portion 41 is erected, and the end surface 51 of the wall portion 41 abuts on the back surface of the cover A11, so that the wall portion 41, the inner wall surface of the body A10, and the back surface of the cover A11 are hollow. A tube 40 is formed, and the acoustic tube 40 is disposed in the small-volume rear air chamber Br. The acoustic tube 40 is a hollow closed tube having a rectangular cross-sectional shape bent along the inner wall surface of the rear air chamber Br, and is formed by opening one end (open end 40a) and closing the other end (closed end 40b). The inside of the pipe communicates with the rear air chamber Br through the open end 40a. An acoustic tube uses the fact that the input impedance becomes extremely small at the resonance frequency of the closed tube (the frequency at which the total length of the tube coincides with an odd multiple of a quarter wavelength). The reflected wave has a waveform whose phase is inverted with respect to the incident wave, and the incident wave and the reflected wave cancel each other, thereby reducing the sound wave propagating from the opening end 40a to the outside.

  Such an acoustic tube 40 is provided to shift the lowest resonance frequency of the speaker SP to the low frequency side and further increase the sound pressure level of the speaker SP. Is set to approximately a quarter wavelength of a low frequency (in the present embodiment, around 700 to 800 Hz), the sound quality and efficiency of the speaker SP can be improved even if the rear air chamber Br has a small capacity.

  Next, a joint structure between the body A10 and the cover A11 that are components of the housing A1 will be described. The body A10 is formed in a substantially rectangular parallelepiped box shape with an open rear surface, and the cover A11 is formed in a substantially rectangular box shape with an open front surface, and the front surface of the cover A11 covers the rear surface of the body A10. And the rear end surface 50 which comprises the outer periphery, and the end surface 51 (refer FIG. 4) of the wall part 41 which comprises the acoustic tube 40 are formed in the rear surface of the body A10, and the rear end surface 50 and the end surface 51 are cover A11. It is assembled in a state where the elastic portion 60 is sandwiched between the rear end surface 50 and the end surface 51 and the back surface of the cover A11.

  The elastic portion 60 is pressed between the rear end surface 50 and the end surface 51 and the back surface of the cover A11, and the elastic force of the elastic portion 60 biases the body A10 and the cover A11 away from each other. Due to this urging force, two locking claws 70 are provided on each side surface of the body A10 (both ends of each side surface in FIG. 2), and two locking holes are formed on each side surface of the cover A11. The cover A11 is attached to the body A10 by being locked to 71 (see FIG. 5). By setting the locking position between the locking claw 70 and the locking hole 71, the deformation amount of the elastic portion 60 can be set to a predetermined amount, and the degree of sealing of the space in the housing A1 by the elastic portion 60 can be reduced. Can be secured. 5A, the rear end face 50 and the end face 51 use separate elastic portions 60, and the rear end face 50 and the end face 51 have the same elastic portion 60 as shown in FIG. 5B. Any of the configurations using may be used.

  In the assembled housing A1, the elastic portion 60 is pressed between the rear end surface 50 and the end surface 51 and the back surface of the cover A11, and the elastic portion 60 improves the sealing performance between the body A10 and the cover A11. Since the rear air chamber Br is a highly sealed space, the reverse phase sound radiated from the back surface of the speaker SP to the rear air chamber Br is difficult to leak out of the housing A1, and the reverse phase sound leaked from the housing A1 is not generated. A decrease in the sound pressure radiated by going forward and canceling out the positive phase sound radiated from the surface of the speaker SP is suppressed, so that the speaker in front can easily hear the sound emitted by the speaker SP.

  In addition, since the acoustic tube 40 also improves the sealing degree between the cover A11 and the wall portion 41 by the elastic portion 60 and suppresses air leakage, the sound quality and efficiency of the speaker SP are reduced without reducing the function as the acoustic tube. Can be improved.

  As the elastic part 60, rubber or thermoplastic elastomer is used. Furthermore, if an elastomer that attenuates the amplitude of the sound wave in the frequency band radiated from the back surface of the speaker SP to the rear air chamber Br is used, sound leakage from the housing A1 can be further suppressed, and the sealing degree of the space is further improved.

  The body A10 and the cover A11 are molded by resin molding, but if the elastic portion 60 is molded integrally with the rear end surface 50 of the body A10 and the end surface 51 of the wall portion 41 by two-color molding, the degree of sealing of the space is increased. More improved. Alternatively, the elastic portion 60 may be bonded to the rear end surface 50 of the body A10 and the end surface 51 of the wall portion 41.

  Next, as shown in FIG. 6, the microphone substrate MB1 includes a module substrate 2 having both surfaces 2a and 2b. A pair of the microphone bare chip BC1 and ICKa1 and a pair of the microphone bare chip BC2 and ICKa2 are connected to the module substrate 2. And mounted between the bare chips BC1, ICKa1, and the wiring pattern (not shown) on the module substrate 2 and between the bare chips BC2, ICKa2 and the wiring pattern (not shown) on the module substrate 2 respectively. After each connection (wire bonding) with W, the shield case SC1 is mounted so as to cover the pair of bare chips BC1 and ICKa1, and the shield case SC2 is mounted so as to cover the pair of bare chips BC2 and ICKa2. BC1, ICKa1, and shield case SC1 Microphones M1 to be provided with a bare chip BC2, ICKa2, microphone M2 composed of the shield case SC2.

  As shown in FIG. 7, in the bare chip BC (bare chip BC1 or BC2), an Si thin film 1d is formed on one surface side of the silicon substrate 1b so as to close the hole 1c formed in the silicon substrate 1b. An electrode 1f is formed between them via an air gap 1e, and a pad 1g for outputting an audio signal is further provided to constitute a capacitor type silicon microphone. Then, an external acoustic signal vibrates the Si thin film 1d, whereby the capacitance between the Si thin film 1d and the electrode 1f changes to change the amount of charge, and the pad 1g changes with this change in the amount of charge. , 1g, a current corresponding to the acoustic signal flows. In this bare chip BC, the silicon substrate 1b is die-bonded on the module substrate 2. In particular, the Si thin film 1d of the bare chip BC2 faces the sound hole F2 formed in the module substrate 2.

  The microphone M1 uses the bottom surface side of the shield case SC1 with the sound hole F1 as a sound collecting surface, and the microphone M2 uses the mounting surface side with respect to the module substrate 2 with the sound hole F2 as a sound collecting surface. The sound collecting surfaces are provided on both sides of the module substrate 2 in opposite directions. Since the microphone substrate MB1 configured in this manner has both the microphones M1 and M2 mounted on the one surface 2a of the module substrate 2, the thickness of the microphone substrate MB1 can be reduced.

  FIG. 8A is a plan view of the microphone board MB1 as viewed from the one surface 2a side of the module board 2. The module board 2 has a rectangular part 2f in which the microphone M1 is arranged and a rectangular part 2g in which the microphone M2 is arranged. And a connecting portion 2h that connects the rectangular portions 2f and 2g, and the rectangular portion 2g is formed larger than the rectangular portion 2f. A negative power supply pad P1, a positive power supply pad P2, an output 1 pad P3, and an output 2 pad P4 are provided along the edge of the rectangular portion 2g.

  Then, as shown in FIG. 8B, the negative power supply pad P1 is connected to the negative side of the power supply voltage supplied from the outside, and the positive power supply pad P2 is connected to the positive side of the power supply voltage. Power is supplied to the microphones M1 and M2 through the pattern. Further, an audio signal collected by the microphone M1 is output from the output 1 pad P3 via a wiring pattern on the module substrate 2, and an audio signal collected by the microphone M2 is output from the output 2 pad P4. It is output via the upper wiring pattern. The ground of the audio signal output from the output pads P3 and P4 is shared by the negative power supply pad P1.

  Thus, the power of the microphones M1 and M2 is supplied from the common negative power supply pad P1 and the positive power supply pad P2, and the ground of each output of the microphones M1 and M2 is shared by the negative power supply pad P1, so that the number of pads The configuration can be simplified.

  Next, the operation of the microphone substrate MB1 will be described.

  First, each current flowing from the bare chips BC1 and BC2 according to the collected acoustic signal is impedance-converted by ICKa1 and Ka2 and converted into a voltage signal, and output from the output 1 pad P3 and the output 2 pad P4 as audio signals, respectively. Is done.

  The ICKa (ICKa1 or Ka2) has the circuit configuration of FIG. 9, and is a constant IC composed of a chip IC that converts the power supply voltage + V (for example, 5V) supplied from the power supply pads P1 and P2 into a constant voltage Vr (for example, 12V). A voltage circuit Kb is provided, a constant voltage Vr is applied to the series circuit of the resistor R11 and the bare chip BC, and a connection midpoint between the resistor R11 and the bare chip BC is connected to the junction type J-FET element S11 via the capacitor C11. Connected to the gate terminal. The drain terminal of the J-FET element S11 is connected to the operating power supply + V, and the source terminal is connected to the negative side of the power supply voltage via the resistor R12. Here, the J-FET element S11 is for electrical impedance conversion, and the voltage at the source terminal of the J-FET element S11 is output as an audio signal. Note that the ICKa impedance conversion circuit is not limited to the above-described configuration, and may be, for example, a circuit having a function of a source follower circuit using an operational amplifier, or an audio signal amplification circuit in the ICKa if necessary. May be provided.

  The microphone board MB1 can efficiently configure the signal lines and the power supply lines by performing signal transmission and power supply via the wiring pattern on the module board 2 as described above, and can be attached to the outer surface of the housing A1. Become. In this embodiment, one surface 2a of the module substrate 2 is arranged along the outer front surface of the housing A1, and the microphone M1 is inserted through the opening 13 on the front surface of the housing A1 so that the sound collection surface faces the front air chamber Bf, and the shield The sound hole F1 of the microphone M1 formed in the bottom surface of the case SC1 faces the diaphragm 23 of the speaker SP, and the sound emitted from the speaker SP can be reliably collected through the sound hole F1. Further, the microphone M2 is fitted into the recess 14 provided in the front surface of the housing A1, and the sound hole F2 of the microphone M2 formed in the module substrate 2 is opposed to the sound hole 61 formed in the front surface of the apparatus main body A2. Furthermore, since it faces the outside (front) of the housing A1 toward the output direction of the speaker SP, the voice from the speaker located in front of the communication device A that is transmitted through the sound hole F2 is surely received. Sound can be collected. If the distances from the center of the speaker SP to the centers of the microphones M1 and M2 are X1 and X2, respectively, X1 <X2.

  Further, since the concave portion 14 in which the microphone M2 is accommodated is a separated space that does not communicate with the rear air chamber Br, the microphone M2 is more difficult to collect the sound emitted by the speaker SP, and the speaker SP and the microphone M2 are separated. The acoustic coupling is further reduced. That is, with the above configuration, the sound emitted from the speaker SP and the sound emitted from the speaker are separated and collected by the microphones M1 and M2.

  Further, when the microphone board MB1 is disposed in the housing A1, it is difficult to maintain the spatial insulation of the rear air chamber Br. However, by attaching the microphone board MB1 to the outer surface of the housing A1 as in the present embodiment, Spatial insulation of the rear air chamber Br can be maintained.

  And in this embodiment, in order to prevent the howling which generate | occur | produces when the microphones M1 and M2 pick up the audio | voice output of the speaker SP, it has the following structures.

  First, as shown in FIG. 10, the signal processing unit 10 e housed in the audio processing unit 10 includes an amplification circuit 30 that non-inverts and amplifies the output of the microphone M <b> 1, and an audio band (300 to 4000 Hz) from the output of the amplification circuit 30. ), A delay circuit 32 that delays the output of the bandpass filter 31, an amplifier circuit 33 that inverts and amplifies the output of the microphone M2, and an audio band from the output of the amplifier circuit 33. A band-pass filter 34 that removes noise at frequencies other than (300 to 4000 Hz), and an adder circuit 35 that adds outputs of the delay circuit 32 and the band-pass filter 34 are provided.

  FIGS. 11 to 14 show the sound signal waveforms of the respective parts of the signal processing unit 10 when the sound from the speakers is collected by the microphones M1 and M2, respectively. First, when the distances from the center of the speaker SP to the centers of the microphones M1 and M2 are X1 and X2, respectively, X1 <X2. Therefore, when the sound from the speaker SP is picked up by the microphones M1 and M2, the output Y21 of the microphone M2 is more than the output Y11 of the microphone M1 depending on the distance between the speaker SP and the microphones M1 and M2 and the directivity of the microphones M1 and M2. And the microphone M2 for the delay time [Td = (X2-X1) / Vs] (Vs is the speed of sound) corresponding to the difference (X2-X1) in the distance between the microphones M1, M2 and the speaker SP. The phase of the output Y21 is delayed (see FIGS. 11A and 11B).

  The amplifier circuit 30 generates an output Y12 obtained by non-inverting amplification of the output Y11, and the amplifier circuit 33 generates an output Y22 obtained by inverting and amplifying the output Y21 and inverting the phase by 180 °. At this time, level adjustment corresponding to the difference (X2−X1) in the distance between the two microphones M1 and M2 and the speaker SP is performed to match the output levels of the two microphones M1 and M2 with respect to the sound from the speaker SP (FIG. 12 ( a) (b)). In the present embodiment, the amplification factor of the amplifier circuit 30 is approximately 1, and the amplifier circuit 30 may be omitted.

  Then, the bandpass filters 31 and 34 generate outputs Y13 and Y23 obtained by removing noise of frequencies other than the audio band from the outputs Y12 and Y22 (see FIGS. 13A and 13B).

  Next, the delay circuit 32 is composed of a time delay element or a CR phase delay circuit, and delays the output of the microphone M1 closer to the speaker SP by the delay time Td, so that the output Y14 of the delay circuit 32 and The phase with the output Y23 of the bandpass filter 34 is matched to reduce noise on the transmitted audio signal.

  Then, the sound component from the speaker SP included in the output Y14 and the sound component from the speaker SP included in the output Y23 have the same amplitude and the same phase by the amplification process and the delay process. By adding Y23, an output Ya in which the audio signal corresponding to the audio from the speaker SP is canceled is generated (see FIGS. 14A to 14C). That is, in the output Ya, the sound component from the speaker SP is reduced.

  On the other hand, for the sound emitted by the speaker H in front of the microphones M1, M2, the amplitude of the output Y21 of the microphone M2 having high directivity with respect to the sound emitted by the speaker H is larger than the amplitude of the output Y11 of the microphone M1. Also grows. Furthermore, since the amplification factor of the amplification circuit 33 is larger than the amplification factor of the amplification circuit 30, the speech component from the speaker H included in the output Y23 is further larger than the speech component from the speaker H included in the output Y14. That is, the amplitude difference between the speech component from the speaker H included in the output Y14 and the speech component from the speaker H included in the output Y23 becomes large, and even if the addition process is performed by the addition circuit 35, the output Ya Therefore, the signal corresponding to the voice uttered by the speaker H remains in a state where the amplitude is maintained sufficiently.

  As described above, the sound component from the speaker SP is reduced at the output Ya of the adder circuit 35, and the sound component emitted from the speaker H in front of the communication device A toward the microphone board MB1 remains, and at the output Ya The relative difference between the speech component from the speaker H to be retained and the speech component from the speaker SP to be reduced increases. That is, even when the sound from the speaker H and the sound from the speaker SP are generated at the same time, only the sound component from the speaker SP is reduced while maintaining a sufficient amplitude for the sound component from the speaker H. Therefore, howling that occurs when the microphones M1 and M2 pick up the sound output of the speaker SP can be prevented.

  Since the reverse phase sound radiated from the back surface of the speaker SP to the rear chamber Br is difficult to leak out of the housing A1 as described above, the microphones M1 and M2 mainly generate the positive phase sound emitted from the surface of the speaker SP. It is possible to reliably perform the howling prevention processing by the signal processing unit 10e without collecting the sound and collecting the speaker sound with the opposite phase leaking from the housing A1.

  Furthermore, since the microphone M2 has the sound collection surface facing the outside of the housing A1, and the output direction of the speaker SP and the directivity of the microphone M2 are substantially the same direction, the acoustic coupling between the speaker SP and the microphone M2 is reduced, and the microphone M2 Makes it difficult to collect the sound emitted by the speaker SP, and the microphone M2 can be disposed adjacent to the vicinity of the speaker SP, and the communication device A can be downsized.

  Next, the voice switch unit 10b is arranged on the transmission line of the received signal, the voice switch unit 10c is arranged on the transmission line of the signal to be transmitted (see FIG. 3), and the voice switch units 10b and 10c are mutually connected. The voice switch section with the smaller input signal level gives a loss amount (for example, 48 dB loss amount) to the transmission line by the variable loss means provided inside. Therefore, a signal having a lower level of the received signal and the transmitted signal is attenuated and the howling margin is further increased (for example, an increase of 48 dB), so that further howling prevention is achieved.

  In the present embodiment, voice signals are exchanged between the call devices A using a wired communication system via the information line Ls. However, by providing the call devices A with known wireless communication means, Voice signals may be exchanged using a communication method.

(Embodiment 2)
In the first embodiment, the call module MJ is stored in the apparatus main body A2. However, in the present embodiment, the housing A1 of the call module MJ is used as the apparatus main body as shown in FIGS. By providing the call switch SW1 in A1, the apparatus main body A2 having another configuration shown in the first embodiment is unnecessary.

  Other configurations are the same as those of the first embodiment, and a description thereof will be omitted.

It is side surface sectional drawing which shows the structure of the communication apparatus of Embodiment 1. (A) (b) It is a perspective view which shows the structure same as the above. It is a circuit diagram which shows the structure of an audio | voice processing part same as the above. It is a top view which shows the structure of a body same as the above. It is side surface sectional drawing which shows the latching | locking part of a body and a cover same as the above. It is side surface sectional drawing which shows the structure of a microphone substrate same as the above. It is side surface sectional drawing which shows the structure of a bare chip same as the above. It is the (a) simplified top view and (b) simplified circuit diagram which show the structure of a microphone substrate same as the above. It is a circuit diagram of an impedance conversion circuit same as the above. It is a circuit block diagram of a signal processing part same as the above. (A) (b) It is a signal waveform diagram of a signal processing part same as the above. (A) (b) It is a signal waveform diagram of a signal processing part same as the above. (A) (b) It is a signal waveform diagram of a signal processing part same as the above. (A)-(c) It is a signal waveform diagram of the signal processing part same as the above. It is side surface sectional drawing which shows the structure of the communication apparatus of Embodiment 2. It is a perspective view which shows a structure same as the above. It is side surface sectional drawing which shows the structure of the conventional telephone apparatus.

Explanation of symbols

A Communication device MJ module A1 Housing A10 Body A11 Cover SP Speaker M1, M2 Microphone Br Rear air chamber 10 Audio processing unit 60 Elastic unit

Claims (5)

A speaker that outputs sound information transmitted from the outside, a first microphone that collects sound and outputs a sound signal, and a speaker far from the first microphone to collect sound. A second microphone that outputs an audio signal and an audio processing unit that removes the audio signal of the first microphone from the audio signal of the second microphone and transmits the signal to the outside, on one side of the speaker Audio information to the outside of the housing,
The housing is configured by bringing a plurality of components into contact with each other, and a rear air chamber that is a space formed on the other surface side of the speaker in the housing and a contact surface of each component in the rear air chamber. A call device comprising: an elastic portion pressed by   The call device according to claim 1, wherein the elastic portion is an elastomer that attenuates the amplitude of sound waves in a predetermined frequency band.   The housing is configured by providing the elastic portion between the contact surfaces of the first component and the second component, the first component is provided with a locking hole, and the second component is the 3. The communication device according to claim 1, further comprising a locking claw that locks into the locking hole by a restoring elasticity of the pressed elastic portion.   The housing is configured by providing the elastic portion between the contact surfaces of the first component and the second component, and the other of the first and second components on the inner surface of the other component An acoustic tube configured by abutting the end surface of the wall portion standing on the inner surface of the component is provided in the rear air chamber, and the elastic portion is between the inner surface of one component and the end surface of the wall portion. 4. The communication device according to claim 1, wherein the communication device is pressed.   5. The communication device according to claim 1, wherein the housing is made of resin, and the elastic portion and the housing are integrally formed.

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