JP4862611B2 - Telephone device - Google Patents

Abstract

A compact intercom device is provided, which efficiently prevents howling phenomenon. This intercom device includes a housing; a speaker accommodated in the housing such that a front air chamber is defined at a front side of the speaker and a rear air chamber is defined as a rear side of the speaker, a first microphone disposed such that its sound receiving surface faces the front air chamber, a second microphone disposed such that its sound receiving surface faces outside of the housing; and a signal processing unit. When an audio output of the speaker is picked up by the second microphone, the signal processing unit removes a signal component corresponding to the audio output of the speaker from an output signal of the second microphone by use of an output signal of the first microphone.

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, as a first conventional example, a loop circuit including a speaker and a microphone is formed in a communication device, and howling occurs when the loop gain exceeds 1, so that loss in a variable loss circuit provided in the loop circuit occurs. Some control the amount so that the loop gain is 1 or less to prevent howling. Here, it is assumed that the smaller signal level of the transmission signal and the reception signal is not important, and the transmission loss of the variable loss circuit inserted in the transmission line having the smaller signal level is increased.

  However, in the first conventional example, when the distance between the microphone and the speaker is short, the level of the received voice that goes from the speaker to the microphone increases, the transmitted signal becomes larger than the received signal, and the voice comes out from the speaker. In spite of the reception state, the control circuit switches to the transmission state, and there is a state in which no sound to be output from the speaker is generated.

  Therefore, as a second conventional 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, both microphones and the speaker The level adjustment amplifier circuit that adjusts the level corresponding to the difference in distance between the two microphones to match the output level of both microphones with the sound from the speaker, and both microphone outputs that have passed through the delay circuit and level adjustment amplifier circuit There has been proposed a communication device that includes a differential amplifier circuit as described above and uses the output of the differential amplifier circuit as a transmission signal.

In this communication device, after picking up the sound from the speaker with a pair of microphones, the delay and level adjustment is performed so that the sound component from the speaker input to both microphones is canceled by the differential amplifier circuit. The transmitted voice can be transmitted in a state in which only the voice component from the speaker is removed and no reception blocking occurs. (For example, see 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)

  However, also in the second conventional example, it is necessary to provide a pair of microphones, and further, in order to prevent howling, the distance between the speaker and the microphone cannot be made very small, and further miniaturization of the apparatus has been desired. .

  In addition, the communication device is becoming thinner and thinner for miniaturization, and the capacity of the housing for housing the speaker is reduced. In particular, if the volume of the rear air chamber, which is the space on the back side of the speaker, is reduced, the sound pressure radiated from the speaker is lowered, the lowest resonance frequency of the speaker is shifted to the higher frequency side, and the sound quality and efficiency of the speaker are deteriorated. There was also.

  The present invention has been made in view of the above reasons, and an object of the present invention is to provide a communication device capable of realizing howling prevention, downsizing, improvement in sound quality and efficiency.

The invention according to claim 1 is electrically connected directly to a first connection portion that is installed on an indoor ceiling surface, wall surface, and floor surface and is electrically connected to at least one system wiring for transmitting power and information signals. And a second connecting portion for receiving and supplying power and exchanging information signals with the first connecting portion, and the configuration of the second connecting portion is changed to the arrangement of the first connecting portion and A housing that is shaped corresponding to the shaping of the shape, a speaker that is arranged in the housing and that outputs audio information transmitted from the outside via the second connection portion from one side, and a housing A front air chamber surrounded by the inner surface and one side of the speaker, a rear air chamber surrounded by the inner surface of the housing and the other surface of the speaker, and a sound collection surface facing the front air chamber, A first microphone that outputs a sound signal obtained by converting the collected sound into an electrical signal; A second microphone that outputs a sound signal obtained by converting the collected sound into an electrical signal with the sound surface facing the outside of the housing, and the sound signal collected by the second microphone is collected by the first microphone. An audio processing unit that removes a sound signal that has been sounded and transmits the sound signal to the outside through a second connection unit, and an acoustic tube disposed in the rear air chamber are provided.

According to the present invention, the sound collecting surface of the first microphone is disposed toward the front air chamber so that the distance between the first microphone and the speaker can be shortened, and the first microphone can be miniaturized. Can reliably collect the sound emitted from the speaker, so that the howling prevention processing by the sound processing unit can be reliably performed. Furthermore, since the second microphone faces the sound collection surface out of the housing, the acoustic coupling between the speaker and the second microphone is reduced, and the second microphone becomes difficult to collect the sound emitted from the speaker. A microphone can be arranged in the vicinity of the speaker, and the communication device can be downsized. Further, the acoustic tube shifts the lowest resonance frequency of the speaker to the low frequency side and further increases the sound pressure level of the speaker, so that the sound quality and efficiency of the speaker are improved. That is, in the communication device, it is possible to realize howling prevention, downsizing, improvement in sound quality and efficiency. Furthermore, if the second connection unit is electrically connected to the first connection unit, the communication device can secure a power path and an information path at the same time, and it is not necessary to perform a new wiring work. Obtainable.

  According to a second aspect of the present invention, in the first aspect, the acoustic tube is set to a length based on a quarter wavelength of a frequency that increases a sound pressure level of an output of the speaker.

  According to the present invention, the lowest resonance frequency of the speaker can be set to a desired frequency, and the sound quality and efficiency of the speaker can be arbitrarily set.

  According to a third aspect of the present invention, in the first or second aspect, the rear air chamber is a space sealed between the inner surface of the housing and the other surface side of the speaker.

  According to the present invention, sound radiated from the other surface of the speaker hardly leaks to the outside of the housing, and acoustic coupling between the speaker and the second microphone is further reduced. Further, the interference between the sound radiated from the one surface side of the speaker and the sound radiated from the other surface side is reduced, and the decrease of the radiated sound pressure of the speaker is prevented.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the plurality of acoustic tubes having different lengths are arranged in the rear air chamber.

  According to the present invention, the sound pressure level of the speaker can be increased at a plurality of frequencies, and desired sound quality and efficiency can be obtained by appropriately setting the length of each acoustic tube.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the resonance frequency of the acoustic tube is not provided with a minimum resonance frequency of a speaker attached to a baffle plate having an infinite size and an acoustic tube. It is set between the lowest resonance frequency of the speaker attached to the housing.

  According to the present invention, it is possible to easily improve the sound quality and efficiency of the speaker.

  According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the acoustic tube is formed along an inner surface of the rear air chamber.

  According to this invention, the capacity reduction of the rear air chamber due to the acoustic tube can be suppressed.

  A seventh aspect of the present invention is characterized in that in any one of the first to sixth aspects, a sound absorbing material is disposed in the opening of the acoustic tube.

  According to the present invention, the sound absorption effect can be enhanced and the resonance frequency of the acoustic tube can be finely adjusted.

  As described above, the present invention has an effect that it is possible to realize howling prevention, downsizing, improvement in sound quality and efficiency.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings . First, a basic configuration of a communication device will be described .

( Basic configuration 1 )
A basic configuration 1 of the communication device A is shown in FIGS. 1 to 3, and a housing A1 is configured by a body A10 having an opening formed on the rear surface and a cover A11 covering the opening of the body A10. A speaker SP, a microphone board MB1, a call switch SW1, and a voice processing unit 10 are provided.

  As shown in FIG. 3, the audio processing unit 10 is composed of an IC including a communication unit 10a, echo cancellation 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 via the information line Ls is received by the communication unit 10a, amplified by the amplification unit 10d via the echo cancellation 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, the signal passes through the echo cancel 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.

  As shown in FIG. 1, the speaker SP is a cylindrical yoke 20 formed of an iron-based material having a thickness of about 0.8 mm such as cold rolled steel plate (SPCC, SPCEN), electromagnetic soft iron (SUY), etc., and having one end opened. The circular support body 21 is extended from the opening end of the yoke 20 toward the outside.

  A cylindrical permanent magnet 22 (for example, residual magnetic flux density of 1.39 T to 1.43 T) formed of neodymium is disposed in the cylinder of the yoke 20, and the outer peripheral edge of the dome-shaped diaphragm 23 is a support. 21 is fixed to the edge surface.

  The diaphragm 23 is formed of a thermoplastic plastic (for example, a thickness of 12 μm to 50 μm) such as PET (PolyEthyleneTerephthalate) or PEI (Polyetherimide). A cylindrical bobbin 24 is fixed to the rear surface of the diaphragm 23, and is formed by winding a polyurethane copper wire (for example, φ0.05 mm) around a paper tube of kraft paper at the rear end of the bobbin 24. A voice coil 25 is provided. 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 that the bobbin 24 moves back and forth with the diaphragm 23. Visible in the direction. At this time, a sound corresponding to the audio signal is emitted from the diaphragm 23. That is, an electrodynamic speaker SP is configured.

  And the rib 11 is formed in the front inner side of housing A1 which the diaphragm 23 of speaker SP opposes, and the end surface of the convex part 21a protruded to the front side from the outer peripheral end part of the circular support body 21 of speaker SP. Comes into contact with the rib 11, and the speaker SP is fixed in a state where the diaphragm 23 faces the front surface of the housing A1 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 housing A1. The rear air chamber Br becomes a space that is insulated (not communicated) with the front air chamber Bf by closely contacting the end portion of the support 21 of the speaker SP and the rib 11 on the inner surface of the housing A1, and further covers the cover A11. Is in close contact with the rear opening of the body A10 to form a sealed space that is insulated from the outside.

  Next, as shown in FIG. 4, the microphone substrate MB1 has a pair of microphone bare chips BC1 and ICKa1 and a pair of microphone bare chips BC2 and ICKa2 mounted on one surface 2a of the module substrate 2, respectively, and bare chips BC1 and ICKa1. After connecting the wiring patterns (not shown) on the module substrate 2 and between the bare chips BC2, ICKa2 and the wiring patterns (not shown) on the module substrate 2 with wires W (wire bonding), 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, so that the microphone constituted by the bare chips BC1, ICKa1, and the shield case SC1. M1, bare chip BC2, I Ka2, and a composed microphone M2 with a shield case SC2.

  As shown in FIG. 5, 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. 6A is a plan view of the microphone substrate MB1 as viewed from the one surface 2a side of the module substrate 2. The module substrate 2 has a rectangular portion 2f in which the microphone portion M1 is disposed and a rectangular portion in which the microphone portion M2 is disposed. The rectangular portion 2g is formed to be larger than the rectangular portion 2f. The rectangular portion 2g is formed by a connecting portion 2h that connects the rectangular portions 2f and 2g. 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. 6B, 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 microphone units M1 and M2 through the pattern. Also, the audio signal collected by the microphone unit M1 is output from the output 1 pad P3 via the wiring pattern on the module substrate 2, and the audio signal collected by the microphone unit M2 is output from the output 2 pad P4 to the module. It is output via a wiring pattern on the substrate 2. The ground of the audio signal output from the output pads P3 and P4 is shared by the negative power supply pad P1.

  As described above, the power of the microphone units 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 microphone units M1 and M2 is also used as the negative power supply pad P1, thereby Can be reduced, and the configuration becomes simple.

  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. 7, 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. Further, 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. The sound hole F1 of the microphone M1 formed in the bottom surface is opposed to the diaphragm 23 of the speaker SP and has high directivity with respect to the sound from the speaker SP transmitted through the sound hole F1, so that the speaker SP is The sound that is emitted can be collected reliably. The microphone M2 is fitted into a 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 located outside (frontward) the housing A1 in the output direction of the speaker SP. Therefore, it has high directivity with respect to the voice transmitted from the speaker located in front of the communication device A, which is transmitted through the sound hole F2. 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, the rear air chamber Br facing the back surface of the speaker SP is sealed in the housing A1, so that sound radiated from the back surface of the speaker SP is difficult to leak from the rear air chamber Br, and the speaker SP and the microphone M2 are not connected. Acoustic coupling is reduced. Furthermore, the sound radiated from the back surface of the speaker SP (the back surface of the diaphragm 23) has a phase reversed from that of the sound radiated from the surface of the speaker SP (the surface of the diaphragm 23). When the generated sound circulates forward, the sound radiated from the surface of the speaker SP cancels each other, the radiated sound pressure of the speaker SP decreases, and the speaker in front cannot hear the sound emitted by the speaker SP. However, since the sound radiated from the back surface of the speaker SP is difficult to leak to the outside of the housing A1 as described above, a decrease in the radiated sound pressure of the speaker SP due to the wraparound is prevented.

  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.

Although it is difficult to maintain the spatial insulation between the air chamber Bf and the rear air chamber Br prior Placing a microphone substrate MB1 in the housing A1, mounting the microphones substrate MB1 on the outer surface of the housing A1 Thus, the spatial insulation between the front air chamber Bf and the rear air chamber Br can be maintained.

Then, in order to prevent the howling which occurs by picking up the sound output of the speaker SP microphones M1, M2 is provided with the following configuration.

  First, as shown in FIG. 8, the signal processing unit 10 e housed in the audio processing unit 10 includes an amplifier 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 amplifier 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.

  9 to 12 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. 9A and 9B).

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. 10 ( a) (b)). Incidentally, the amplification factor of amplifier circuit 30 is set to substantially 1, the amplifying circuit 30 may be omitted.

  Then, the band pass 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. 11A and 11B).

  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. 12A to 12C). 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.

  In addition, since the microphone M1 reliably collects the sound emitted from the speaker SP, the howling prevention processing by the signal processing unit 10e can be reliably performed. 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 arranged adjacent to the speaker SP, that is, adjacent to the front air chamber Bf, and the communication device A can be downsized.

Next, the audio signal output from the adder circuit 35 is output to the echo canceling unit 10c, and the echo canceling units 10b and 10c (see FIG. 3) perform the following processing to further prevent howling.

  First, the echo canceling unit 10c captures the output of the echo canceling unit 10b as a reference signal, and performs an operation on the output of the signal processing unit 10e, thereby further processing the audio signal that has circulated from the speaker SP to the microphones M1 and M2. Cancel. On the other hand, the echo canceling unit 10b also captures the output of the echo canceling unit 10c as a reference signal and performs an operation on the output of the communication unit 10a, thereby wrapping the audio signal from the speaker to the microphone on the other party side Cancel.

  Specifically, the echo cancellation units 10b and 10c are configured by a speaker SP-microphone M1, M2-signal processing unit 10e-echo cancellation unit 10c-communication unit 10a-echo cancellation unit 10b-amplification unit 10d-speaker SP. By adjusting the amount of loss in a variable loss means (not shown) provided in the loop circuit, the loop gain is set to 1 or less to prevent howling. Here, it is assumed that the smaller signal level of the transmission signal and the reception signal is not important, and the transmission loss of the variable loss circuit inserted in the transmission line having the smaller signal level is increased.

Further, in the air chamber Br After the back side of the speaker SP, and open acoustic tube 40 which closes the other end is arranged at one end, the acoustic tube 40 is provided along the inner surface of the body A10 . Then, by appropriately setting the resonance frequency of the acoustic tube 40, the lowest resonance frequency of the speaker SP shifts to the low frequency side, and further, the sound pressure level of the speaker SP increases, so that the sound quality and efficiency of the speaker SP are improved. improves.

Note that the minimum resonance frequency fo of the speaker is generally equivalent to the equivalent mass (diaphragm, coil, additional air mass) Mo of the vibration system of the speaker, the stiffness So such as an edge supporting the same, and the air in the rear air chamber Br. And the stiffness Sc of
fo = {1 / (2π)} · √ {(So + Sc) / Mo}
It is represented by

  FIG. 13 shows the frequency characteristics of the sound component cancellation amount of the speaker SP by the signal processing unit 10e, and FIG. 14 shows the frequency characteristics of the radiated sound pressure in front of the speaker SP, and the acoustic tube 40 is omitted from the housing A1. Each result is shown for both the case where the housing is used and the case where an ideal baffle plate is used as the housing.

  First, an ideal baffle plate is a baffle plate C having an infinite size as shown in FIG. 15, and a cancellation amount when the speaker SP and the microphone substrate MB1 are attached to the baffle plate C (see FIG. 15). 13 characteristic Y1a) maintains 10 dB or more in the frequency band of 100 Hz to 10000 Hz, and the radiation sound pressure characteristic (characteristic Y2a in FIG. 14) is the lowest resonance frequency fo1 = 600 Hz of the speaker SP, and the lowest resonance frequency is the speaker SP alone. It shows the same ideal characteristics as When the baffle plate C is used, it has such excellent characteristics. This is because the baffle plate C has an infinite size, and the sound emitted from the back surface of the speaker SP (the back surface of the diaphragm 23) is baffled. This is the result when it is blocked by the plate C and does not go forward, and is not realistic.

Next, the cancellation amount (characteristic Y1b in FIG. 13) when the housing without the acoustic tube 40 is used is also maintained at 10 dB or more in the frequency band 100 Hz to 10000 Hz, and is substantially the same as when the baffle plate C is used. The amount of cancellation can be obtained. However, as for the radiation sound pressure characteristics when the rear air chamber Br is sealed, the same characteristics as the baffle plate C can be obtained if the capacity of the rear air chamber Br is sufficiently large, but the capacity of the rear air chamber Br is small. If it is small, the mechanical equivalent stiffness of the rear air chamber Br becomes large, the lowest resonance frequency of the speaker SP becomes high, the radiated sound pressure decreases, and the speech quality and efficiency deteriorate. For example, the radiated sound pressure characteristic (characteristic Y2b in FIG. 14) when using a housing having the same capacity as the rear air chamber Br of the housing A1 and omitting the acoustic tube 40 is the lowest resonance frequency fo2 of the speaker SP = 1200 Hz, and the baffle Compared with the case where the plate C is used, the lowest resonance frequency is shifted to the high frequency side, and further, the sound pressure level is reduced by about 5 to 20 dB as compared with the case where the baffle plate C is used in a frequency band of 800 Hz or less, The sound quality and efficiency of the speaker SP are deteriorated. The radiated sound pressure characteristic (characteristic Y2c in FIG. 14) in the case of using a housing in which the capacity of the rear air chamber Br of the housing A1 is three times the volume and the acoustic tube 40 is omitted is the lowest resonance frequency fo3 = 800 Hz of the speaker SP. The sound quality of the speaker SP is improved as compared with the case where the capacity of the air chamber Br is small. However, if the capacity of the rear air chamber Br is increased, the housing becomes larger and it becomes difficult to reduce the size of the communication device. Therefore , by providing the acoustic tube 40 in the small- volume rear air chamber Br, the sound quality and efficiency of the speaker SP are improved while reducing the size of the communication device.

FIGS. 16A to 16C show another housing A2 including the acoustic tube 40. The operation of the acoustic tube 40 will be described below by taking the housing A2 as an example. The housing A2 is composed of a body A20 having an opening on the rear surface and a cover A21 covering the opening of the body A20 (however, FIG. 16 (b) shows only the body A20). Like the housing A1, the speaker SP, the microphone board MB1, the call switch SW1, and the sound processing unit 10 are provided, and the acoustic tube 40 is provided in the body A20. The acoustic tube 40 allows the desired frequency of the sound emitted by the speaker SP. The sound quality and efficiency are improved by increasing the sound pressure level in the band ( near 700 Hz ).

The space A2a in which the speaker SP of the housing A2 is arranged is separated from the other space A2b in the housing A2, and the space A2a is formed to be 30 mm wide × 40 mm long × 8 mm thick. In this space A2a, mounting holes (not shown) for the speaker SP are respectively mounted on four cylindrical bosses 51 formed at equal intervals on the inner side of the front surface of the body A20, and are formed in the axial direction of the bosses 51. When the speaker SP is fixed to the front inner side of the body A20 by screwing a mounting screw (not shown) into the screw hole 52 , the front inner side of the housing A2 and the front side of the speaker SP (the diaphragm 23 side) The front air chamber Bf, which is a space surrounded by the rear surface of the housing A1, and the rear air chamber Br, which is a space surrounded by the rear surface side (yoke 20 side) of the speaker SP, is substantially the same as the housing A1. Formed. A plurality of sound holes 53 are formed in the front surface of the housing A2.

The acoustic tube 40 is a tube having a rectangular cross-sectional shape formed along the inner wall of the rear air chamber Br on the back surface of the speaker SP and extending around the rear air chamber Br over approximately ¾, and has one end 40a. And the other end 40b is closed. The total length L of the acoustic tube 40 is set to approximately ¼ wavelength of the frequency f at which the sound pressure level is desired to be increased. Specifically, since the opening end correction of the acoustic tube 40 is performed, if the sound velocity is C and the opening end correction value is σ (= 0.8d, where d is the opening diameter of the acoustic tube 40),
f = [C / {4 (L + σ)}] (1)
It is requested from. In this configuration, the total length L of the acoustic tube 40 is 95.2 mm, and the cross-sectional area of the acoustic tube 40 is 4.2 mm ² (equivalent to φ2.3). Further, by forming the acoustic tube 40 along the inner wall of the rear air chamber Br, the capacity reduction of the rear air chamber Br by the acoustic tube 40 can be suppressed.

  Also, the acoustic tube 40 utilizes the fact that the input impedance is extremely small at the resonance frequency of the closed tube (the frequency at which the total length of the tube matches an odd multiple of a quarter wavelength), so that the sound wave radiated from the back surface of the speaker SP can be obtained. By reflecting on the back side of the speaker SP, the sound leaking from the rear chamber Br to the outside is reduced.

  The resonance frequency of the acoustic tube 40 is the lowest resonance frequency fo4 (= 1200 Hz) when the housing A2 not including the acoustic tube 40 is used, and the lowest resonance frequency when the baffle plate C shown in FIG. 14 is used. By setting the total length L of the acoustic tube 40 so as to be positioned between fo1 (= 600 Hz), the lowest resonance frequency fo5 (= 700 Hz vicinity) of the speaker SP when the housing A2 including the acoustic tube 40 is used. ) Is set between fo1 and fo4.

  FIG. 17 shows radiated sound pressure characteristics of the communication device using the housing A2 including the acoustic tube 40 and the communication device using the housing A2 not including the acoustic tube 40. The characteristic Y3a provided has a sound pressure level increased by about 5 to 10 dB in a frequency band of 800 Hz or less compared with the characteristic Y3b not provided with the acoustic tube 40, and the lowest resonance frequency is from fo4 = 1200 Hz to fo5 = 700 Hz. As the speaker efficiency is improved, the sound quality is improved. For example, in the vicinity of 700 Hz, the sound pressure level increases by about 10 dB, and the improvement of the speaker efficiency due to the increase of the sound pressure level corresponds to a reduction in input current of the speaker SP by 70% and an input power by 90%. Thus, since the sound pressure level of the speaker SP increases in the vicinity of the lowest resonance frequency of the speaker SP, if the entire length of the acoustic tube 40 is appropriately set and the lowest resonance frequency of the speaker SP is shifted to the low frequency side, The sound quality and efficiency of the speaker SP can be improved.

  Further, as shown by a broken line in FIG. 16B, the sound absorbing effect is enhanced by disposing a sound absorbing material 45 such as a non-woven fabric in the opening 40a of the acoustic tube 40 or in the vicinity of the opening 40a, thereby resonating the acoustic tube 40. The frequency can be finely adjusted.

  As another form of the acoustic tube, an acoustic tube 41 communicating with the rear air chamber Br may be provided outside the housing A3 as shown in the schematic diagram of FIG. 18. For example, the tubular acoustic tube 41 is connected to the rear air chamber Br. It may be inserted in the form. When a urethane tube or the like is used for the acoustic tube 41, the total length L can be arbitrarily set and changed.

Similarly to the basic configuration 1 , the microphone substrate MB1 has one surface 2a of the module substrate 2 arranged along the outer front surface of the housing A2 or A3, and the microphone M1 is inserted through the front surface of the housing A2 or A3 and the speaker SP. The microphone M2 has a high directivity with respect to the sound from the speaker located in front of the housing A1 facing the outside (front) of the housing A1. Have.

( Basic configuration 2 )
In the basic configuration 1 , one acoustic tube is provided in the housing. However, in the basic configuration 2 , as shown in the schematic diagram of FIG. 19, a plurality of acoustic tubes 42, 43, and 44 (in this case, in the rear air chamber Br of the housing A4. Since the lengths of the acoustic tubes 42, 43, and 44 are different from each other, the resonance frequencies thereof are also different from each other. Therefore, the sound pressure level of the speaker SP can be increased at a plurality of frequencies, and desired sound quality and efficiency can be obtained by appropriately setting the overall lengths of the acoustic tubes 42, 43, and 44.

Next, an embodiment of the present invention to which the basic configuration 1 or 2 of the above communication device is applied will be described.

(Embodiment)
An example of a wiring system using the communication device of the present invention will be described below.

  First, as shown in FIG. 20, one or a plurality of switch boxes 82 embedded in appropriate positions in a building are provided, and a power line Lp and an information line Ls previously wired in a wall surface between the switch boxes 2 are provided. In addition to feeding wiring, a power line Lp drawn indoors through the main breaker MB and branch breaker BB in the distribution board 81 is introduced to the switch box 82 at the start, and a gateway is connected to the external Internet network NT. An information line Ls connected through a GW (router and hub built-in) is introduced. Here, the switch box 82 is provided at a high position HP such as an indoor ceiling surface, the switch box 82 is provided at a middle position MP at a height recommended by a wall switch or the like, and a low position LP near a foot. It is divided into what is provided.

  These switch boxes 82 are standardized corresponding to a series of mounting frames 84 (see FIG. 21) to which three large-sized square-type embedded wiring devices standardized by JIS can be mounted. As shown in FIG. 22, the power line Lp and the information line Ls sent from the wiring board 81 or other switch box 82 are introduced from the upper part as shown in FIG. 22, and the other switch box 82 is introduced from the lower part. A power line Lp and an information line Ls for sending and wiring are derived. The body of the gate device 83 to which the basic function module 90 is connected is attached to each switch box 82 by an attachment frame 84.

  As shown in FIG. 21, the mounting frame 84 is provided with a window hole 84a for mounting an instrument in the center, and the front part of the instrument body to be mounted is fitted into the window hole 84a from the back, so that the left and right frame pieces The locked body provided on the both sides of the device main body is locked by the locking means provided on the device to fix the device main body. Then, by fastening an attachment screw (not shown) inserted into the attachment hole 84b provided in the upper and lower frame pieces to a screw hole (not shown) of the switch box 82, the entire instrument body is attached to the switch box 82. In addition, when the mounting is performed on the wall panel having the embedded hole opened without using the switch box 82, the wall panel can be clamped with a so-called clip fitting or can be mounted with a wood screw.

  As shown in FIG. 22, the gate device 83 is provided with connection terminal portions 85a and 85b having a quick connection terminal structure and connection terminal portions 85a ′ and 85b ′ for feed wiring on the back surface of the body, and corresponding power lines Lp and information lines. Ls is connected. Further, on the front surface of the body, a power path connection port CN1A having a contact portion electrically connected to the sent power line Lp, and an information path electrically connected to the sent information line Ls A modular connection port CN1 having a connection port CN1B is provided as shown in FIG.

  These connection ports CN1A and CN1B are standardized as a system in terms of the distance between them, the arrangement of the internal contact portions, the shape of the openings, etc., and the front surface of the switch box 82 so as to cover the front surface of the body of the gate device 83. Connected portions CN2A and CN2B of the connector CN2 provided on the back surface of the basic function module 90 shown in FIG. 23 attached to the opening side are detachably coupled to the connection ports CN1A and CN1B.

  The basic function module 90 constitutes a functional device with an extended function module 91 to be described later, and a plurality of types of basic function modules 90 are prepared depending on functions, and the synthetic resin shown in FIG. 23 and FIG. A circuit (corresponding to each function) is built in a flat module main body 90a made of (non-crystalline general-purpose plastic such as ABS), and the connected portions CN2A, CN2B of the connector CN2 on the back surface are connected to the connection ports CN1A, CN1A, By joining to CN1B, the front opening of the switch box 82 is covered, and the peripheral flange is overlaid on the wall surface around the front opening of the switch box 82, and in that state, the upper and lower centers are perforated. A mounting screw (not shown) is inserted into the mounting hole 90b from the front side, and screwed into the screw hole 84c provided in the upper and lower frames of the mounting frame 84. It is attached via a mounting frame 84 to the switch box 28 in Rukoto.

  Further, on the front surface of the module main body 90a, a wide groove 93a and a narrow width are formed in the width direction of the module main body 90a as shown in FIG. 24A at positions above or below the opening positions of the upper and lower mounting holes 90b. A connecting groove portion 93 formed of a groove 93b is formed to be divided into left and right by a central partition wall 94.

In the connecting groove 93 on the left or right side of the partition wall 94, one half of the synthetic resin connecting body 100 shown in FIG. 24B is fitted to a position where it contacts the partition wall 94, and the other half of the connecting body 100 is shown in FIG. As shown in FIG. 25, the basic function module 90 and the extended function module 91 can be mechanically coupled by fitting into a connecting groove 93 that is similarly provided on the extended function module 91 side. The connecting body 100 is provided with a groove 100a on the rear surface where a partition wall 95 that partitions the wide groove 93a and the narrow groove 93b is fitted, and is inserted so as to straddle both the grooves 93a and 93b. In the basic function module 90, the decorative cover 90c is detachably attached from the front surface side, and in the extended function module 91, the lid portion 96 is closed so as to be fitted over the connecting groove portion 93. A certain connected body 100 is held so as not to fall off and is maintained in a connected state. Thus, the connecting body 100 and the connecting groove 93 constitute a connecting means for the basic function module 90 and the extended function module 91.

  One side of both side surfaces of the module main body 90a of the basic function module 90 is provided with a male power connector CN3A and an information connector CN3B, and the other side is provided with a female power connector CN3A 'and an information connector CN3B'. Yes. Then, by connecting the contact piece of the connected portion CN2A to the contact pieces of the power connectors CN3A and CN3A ′, the commercial power supply AC is supplied even if the extended function module 91 is coupled in either the left or right direction. To be able to. Further, by connecting the input / output of the internal circuit to the contact pieces of the information connectors CN3B and CN3B ', information signals can be exchanged even if the extended function module 91 is connected in either the left or right direction. The power connectors CN3A and CN3A ′ are arranged to be biased toward one end on both side surfaces of the module main body 90a, and the information connectors CN3B and CN3B ′ are biased to the other end side on both side surfaces of the module main body 90a. Arranged.

  These power connectors CN3, CN3A ′ and information connectors CN3B, CN3B ′ are standardized as a system in the arrangement of the internal contact portions, the shape of the openings, and the information on the power connector and information arranged on the same plane. The distance from the connector for the connector is also standardized as a system, and power connectors CN4A and CN4A ′, which will be described later, and the information connectors CN4B and CN4B ′ of the extended function module 91 are detachably coupled.

  Then, the basic function module 90 converts the commercial power supply AC supplied via the connected part CN2A into an operating power supply for the internal circuit consisting of a stable DC voltage, and commercial power via the power connectors CN3 and CN3A ′. The power supply AC is supplied, and information signals transmitted and received bidirectionally through the information line Ls connected via the connected portion CN2B can be transmitted and received, and information signals can be transmitted and received via the information connectors CN3B and CN3B ′. A plurality of types of basic function modules 90 are prepared depending on functions.

  Next, in the wiring system of the present embodiment, a plurality of types of extended function modules 91 are prepared depending on the function that operates upon receiving power supply, and the extended function module 91 includes a power connector CN4A as shown in FIG. , CN4A ′ and information connectors CN4B, CN4B ′, and commercial power AC supplied via one of the power connectors CN4A, CN4A ′ is used as an operating power supply for an internal circuit composed of a stable DC voltage. In addition to the conversion, commercial power AC is supplied via one of the power connectors CN4A and CN4A ′, and information signals can be transmitted and received via the information connectors CN4B and CN4B ′.

  In the extended function module 91, basically, as shown in FIG. 26A, the height of the module main body 91a is standardized to the same height as that of the basic functional module 90, and the width dimension is also standardized. Standardized to an integral multiple of the unit module dimensions.

  In addition, a male power connector CN4A and an information connector CN4B are provided on one side of both sides of the flat module body 91a made of synthetic resin (amorphous general-purpose plastic such as ABS), and a female power source is provided on the other side. Connector CN4A ′ and information connector CN4B ′ are provided. The power connectors CN4A and CN4A ′ are arranged to be biased to one end on both side surfaces of the module main body 91a, and the information connectors CN4B and CN4B ′ are biased to the other end side on both side surfaces of the module main body 91a. Be placed. These power connectors CN4A and CN4A ′ and information connectors CN4B and CN4B ′ are arranged in the same manner as the power connectors CN3A and CN3A ′ and information connectors CN3B and CN3B ′ of the basic function module 90. The shape of the unit is standardized as a system, and the interval between the power connector and the information connector arranged on the same surface is also standardized as a system. The power connectors CN3A and CN3A ′ of the basic function module 90 are standardized. The information connectors CN3B and CN3B ′, or the power connectors CN4A and CN4A ′ and the information connectors CN4B and CN4B ′ of other extension function modules 91 are detachably coupled.

  Specifically, the male power connector CN4A and the information connector CN4B are the female power connector CN3A ′, the information connector CN3B ′ of the basic function module 90, or the female connector of the other extended function module 91. Connected to the power connector CN4A ′ and the information connector CN4B ′, the female power connector CN4A ′ and the information connector CN4B ′ are the male power connector CN3A, the information connector CN3B of the basic function module 90, or The other extension function module 91 is connected to the male power connector CN4A and the information connector CN4B.

  In the module main body 91a, the contact pieces of the power connectors CN4A and CN4A ′ are connected to each other, and the power connector on one side is fitted to the power connector of the adjacent basic function module 90 or the extended function module 91. When the power is received (power reception port), the other power connector is the power supply side (power supply port).

  Furthermore, by connecting the input / output of the internal circuit to the contact pieces of the information connectors (information transfer ports) CN4B, CN4B ′, the basic function module 90 and other extended function modules 91 are connected in either direction. Also, information signals can be exchanged, and information signals can be exchanged between the basic function module 90 or the extended function module 91 adjacent to both sides.

  The shape of the module main body 91a of the extended function module 91 is such that the back surface is formed as a flat surface as shown in FIGS. The upper and lower positions are provided with a connecting groove portion 93 including a wide groove 93a and a narrow groove 93b for inserting the connecting body 100 in the same manner as the basic function module 90, and a lid portion for opening and closing the connecting groove portion 93. 96 is provided, and the lid 96 is opened when the connecting body 100 is attached or removed, and is closed as described above when the attached state of the connecting body 100 is maintained (FIG. 26 (c)). )reference).

If the basic function module 90 and the extended function module 91 are provided with the same configuration as the communication device having the basic configuration 1 or 2, a communication device that achieves prevention of howling, miniaturization, sound quality, and efficiency in the wiring system can be obtained. Can be configured.

FIG. 27 shows a basic function module 90A (hereinafter referred to as a telephone call) in which the module main body 90a includes a speaker SP, a microphone board MB1, a front air chamber Bf, a rear air chamber Br, an acoustic tube, and the like in the same manner as the communication device having the basic configuration 1 or 2. A plurality of sound holes 90d are formed in the front surface of the module main body 90a, and the call switch SW1 and the alarm release switch SW2 are exposed on the front surface. The end cover 101 is attached to both sides of the module main body 90a.

Similar to the basic configuration 1 or 2 , the module main body 90 a includes the audio processing unit 10 to prevent howling that occurs when the microphone picks up the audio output of the speaker SP. Further, when an alarm signal is transmitted from the basic function module 90 or the extended function module 91 having a sensor function installed in the room where the communication device 90A is disposed, or another room via the information line Ls, An alarm sound is emitted from the speaker SP, but the alarm sound output can be canceled by operating the alarm cancel switch SW2.

The communication device 90A is capable of securing the power path and the information path at the same time by connecting to the power line Lp and the information line Ls, which are wired in advance in advance, through the gate device 83, and it is necessary to newly perform wiring work. There is no workability. Further, by using the same information line Ls as that of the other basic function module 90 and the extended function module 91, it is possible to easily perform interlocking control between the telephone device 90A and the other basic function module 90 and the extended function module 91. Can be expanded and has excellent extensibility.

FIG. 28 shows an extended function module 91A (hereinafter referred to as a call) in which the module main body 91a includes a speaker SP, a microphone board MB1, a front air chamber Bf, a rear air chamber Br, an acoustic tube, and the like in the same manner as the communication device having the basic configuration 1 or 2. A plurality of sound holes 91d are formed in the front surface of the module main body 91a, and the call switch SW1 and the alarm release switch SW2 are exposed on the front surface.

  Then, for example, the basic function module 90 constituting the wall switch N4 for turning on / off the luminaire is connected to the gate device 83, and the time display unit N6 is exposed on the right side of the basic function module 90 so as to function as a clock. An intercom function can be added to various functional devices such as a wall switch function and a clock function by connecting the extension function module 91 having the function and connecting the call device 91A to the right side of the extension function module 91. it can. Also, a new extended function module 91 can be connected to the telephone device 91A.

  The communication device 91A connects the power path and the information path to the power line Lp and the information line Ls, which are wired in advance, through the gate device 83, the basic function module 90, and another extended function module 91. It can be secured at the same time, and there is no need for new wiring work, so it is excellent in workability. Further, by using the same information line Ls as that of the basic function module 90 and the other extended function module 91, it is possible to easily perform the interlock control between the communication device 91A, the basic function module 90, and the other extended function module 91. Can be expanded and has excellent extensibility.

  The basic function module 90 and the extended function module 91 are prepared in a plurality of types depending on the functions. For example, as shown in FIG. 20, one or a plurality of switch boxes 82 embedded and disposed at appropriate positions in the building. Among them, the gate device 83 of the switch box 82 provided in the high position HP includes a basic function module 90 having a hooking blade connecting portion N1, a basic function having only a speaker N3 and a function for BGM. A module 90 is connected to the basic function module 90, and an extended function module 91 provided with a human sensor N2 is connected to the basic function module 90.

  Connected to the gate device 83 of the switch box 82 provided at the middle position MP is a basic function module 90 that constitutes a wall switch N4 for turning on / off the luminaire and a basic function module 90 including a monitor device N5. The basic function module 90 is connected with an extended function module 91 having a clock N6 and an extended function module 91A (calling device 91A) having an intercom function.

  Further, a basic function module 90 having a power outlet N7 and a basic function module 90 having a speaker N3 are connected to the gate device 83 of the switch box 82 provided in the low position LP. An extended function module 91 constituting the foot lamp N8 is connected.

  After the installation work is completed and the system is completed as described above, information signals are exchanged between the corresponding basic function module 90 and the extended function module 91. An interphone system is configured with the apparatus, enabling a call between the two and performing alarm notification.

It is side surface sectional drawing which shows the structure of the communication apparatus of the basic composition 1 . It is a perspective view which shows a 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 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 a figure which shows the cancellation amount by a signal processing part. It is a figure which shows the radiation sound pressure characteristic of a speaker. It is a partial side sectional view showing the composition at the time of using an ideal baffle board. (A)-(c) It is side surface sectional drawing which shows an example of a housing. It is a figure which shows the cancellation amount at the time of using a housing same as the above. It is side surface sectional drawing which shows another housing same as the above. It is side surface sectional drawing which shows the housing of the basic composition 2 . It is a block diagram of the wiring system using the communication apparatus of embodiment . It is a front view of the state which attached the gate apparatus same as the above to the attachment frame. It is a perspective view which shows the wiring form to the gate apparatus same as the above. It is a perspective view of the state which removed the basic functional module same as the above from the switch box. (A) is a perspective view of the basic functional module same as above with a decorative cover removed, and (b) is a perspective view of a connector. It is explanatory drawing of the connection structure of a basic function module same as the above and an expansion module. The extended function module same as the above is shown, (a) is a front view, (b) is a side view, and (c) is a side view in a state where a lid is opened and a coupling body is removed. It is a perspective view which shows the arrangement | positioning state of the wiring system using the communication apparatus (basic function module) same as the above. It is a perspective view which shows the arrangement | positioning state of the wiring system using the telephone apparatus (extended function module) same as the above.

Explanation of symbols

A Communication device A1 Housing SP Speaker MB1 Microphone board M1, M2 Microphone Bf Front air chamber Br Rear air chamber 10 Audio processing unit 40 Acoustic tube

Claims (7)

Connected directly to a first connection portion that is installed on an indoor ceiling surface, wall surface, floor surface and electrically connected to at least one system wiring for transmitting power and information signals, and receives power supply; Provided with a second connection part for transmitting and receiving information signals to and from the first connection part, the form of the second connection part is used to form the arrangement of the first connection part and the form of the shape A correspondingly shaped housing,
A speaker that is arranged in the housing and outputs audio information transmitted from the outside via the second connection portion from one side;
A front air chamber surrounded by the inner surface of the housing and one side of the speaker;
A rear air chamber surrounded by the inner surface of the housing and the other surface of the speaker;
A first microphone that outputs a sound signal obtained by converting the collected sound into an electrical signal, with the sound collection surface facing the front air chamber;
A second microphone that outputs a sound signal obtained by converting the collected sound into an electrical signal, with the sound collection surface facing out of the housing;
An audio processing unit that removes the audio signal collected by the first microphone from the audio signal collected by the second microphone and transmits the same to the outside via the second connection unit ;
A communication device comprising an acoustic tube disposed in a rear air chamber.   2. The communication apparatus according to claim 1, wherein the acoustic tube is set to a length based on a quarter wavelength of a frequency that increases a sound pressure level of an output of a speaker.   The communication apparatus according to claim 1, wherein the rear air chamber is a space sealed between the inner surface of the housing and the other surface side of the speaker.   4. The communication apparatus according to claim 1, wherein a plurality of the acoustic tubes having different lengths are arranged in the rear air chamber.   The resonance frequency of the acoustic tube is set between the lowest resonance frequency of the speaker attached to the baffle plate having an infinite size and the lowest resonance frequency of the speaker attached to the housing without the acoustic tube. The call device according to any one of claims 1 to 4, wherein   The telephone device according to claim 1, wherein the acoustic tube is formed along an inner surface of the rear air chamber.   The communication device according to any one of claims 1 to 6, wherein a sound absorbing material is disposed in an opening of the acoustic tube.

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