JP2008135860A - Speech communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a speech communication device capable of preventing howling, being made compact in size, and achieving improvement in sound quality and efficiency. <P>SOLUTION: The speech communication device includes a housing A1; a speaker SP which is disposed in the housing A1 and outputs speech information transmitted from the outside from a diaphragm provided on a surface; a front air chamber Bf enclosed by the internal surface of the housing A1 and the front-surface side of the speaker SP; a rear air chamber Br enclosed by the internal surface of the housing A1 and the rear-surface side of the speaker SP; a first microphone M1 disposed having a sound collection surface directed to the inside of the front air chamber Bf; a second microphone M2 disposed having a sound collection surface directed to the outside of the housing A1; a speech processing section 10 which removes a speech signal picked up by the first microphone M1 from a speech signal picked up by the second microphone M2 and transmits the resulting signal to the outside; and a port 40 for making the front air chamber Bf communicate with the outside of the housing A1. <P>COPYRIGHT: (C)2008,JPO&INPIT

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. It is possible to remove the voice component from the speaker to prevent howling, and to transmit the transmitted voice without receiving blocking. (For example, refer to Patent Document 1).

Further, as a third conventional example, in order to improve the frequency characteristics of the speaker output, particularly the sound pressure level at a low frequency, the back surface side of the speaker housed in the enclosure is sealed, and the wall surface of the enclosure facing the speaker surface There is known a so-called kelton-type enclosure in which a port is provided and audio is output to the outside only through this port.
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)

  In recent years, telephone devices have become thinner and thinner for miniaturization, and the capacity of housings for housing speakers has become smaller. 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. was there.

  Further, as in the second conventional example, a call device that cancels only a sound component from a speaker has a pair of microphones, a microphone that collects sound from the speaker and a microphone that collects sound emitted by a speaker. In addition, the distance between the speaker and the microphone cannot be reduced so as to prevent howling, and it is difficult to reduce the size of the apparatus. Further, there has been no communication apparatus that prevents such howling by providing such a pair of microphones and having the same configuration as that of the above-mentioned kelton-type enclosure to improve the sound quality and efficiency of the speaker.

  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.

  According to the first aspect of the present invention, the front air surrounded by the housing, the speaker disposed in the housing and outputting the audio information transmitted from the outside from one surface side, the inner surface of the housing and the one surface side of the speaker. The rear air chamber enclosed by the chamber, the inner surface of the housing and the other surface of the speaker, and the sound collection surface are arranged facing the front air chamber, and the sound signal obtained by converting the collected sound into an electrical signal is output. A first microphone that is arranged, a second microphone that outputs a sound signal obtained by converting the collected sound into an electric signal, and a sound collected by the second microphone. An audio processing unit that removes the audio signal collected by the first microphone from the signal and transmits the signal to the outside, and a port that communicates the front air chamber to the outside of the housing.

  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. Also, the lowest resonance frequency of the speaker is shifted to the lower frequency side by the port, and further the sound pressure level of the speaker is increased, 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.

  According to a second aspect of the present invention, in the first 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 third aspect of the present invention, in the first or second aspect, the first microphone is disposed to face a diaphragm of the speaker.

  According to the present invention, since the first microphone reliably collects the sound emitted from the speaker, the howling prevention process by the sound processing unit can be reliably performed.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the lowest resonance frequency of the speaker is higher than the lowest resonance frequency of a speaker attached to a baffle plate having an infinite size and lower than 1 KHz. The volume of the front air chamber and the rear air chamber and the shape of the port are set so that another resonance frequency of the speaker is higher than 1 KHz and lower than 3 KHz.

  According to the present invention, the call quality in the call voice band is improved.

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

  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 a housing A1 is constituted 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 cylindrical port 40 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), A shield case SC1 is mounted so as to cover the pair of bare chips BC1 and ICKa1, and a shield case SC2 is mounted so as to cover the pair of bare chips BC2 and ICKa2, so that the microphone configured by the bare chips BC1, ICKa1, and 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 includes a rectangular portion 2f in which the microphone M1 is disposed and a rectangular portion 2g in which the microphone M2 is disposed. 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. 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 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. 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. 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. 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 is possible to reliably collect the sound transmitted from the speaker located in front of the communication device A and 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.

  Further, when the microphone substrate MB1 is disposed in the housing A1, it is difficult to maintain the spatial insulation between the front air chamber Bf and the rear air chamber Br, but the microphone substrate MB1 is disposed in the housing as in the present embodiment. By attaching to the outer surface of A1, the spatial insulation between the front air chamber Bf and 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. 8, 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 a frequency other than the audio band from the output of the amplification circuit 30. A band-pass filter 31 that removes noise, a delay circuit 32 that delays the output of the band-pass filter 31, an amplifier circuit 33 that inverts and amplifies the output of the microphone M2, and noise of a frequency other than the audio band from the output of the amplifier circuit 33 And a delay circuit 32 and an adder circuit 35 for adding the outputs of the bandpass filter 34.

  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 sensitivity of the microphones M1 and M2. The amplitude of the microphone M2 is small and the sound wave delay time [Td = (X2-X1) / Cv] (Cv is the speed of sound) corresponding to the difference (X2-X1) in the distance between the microphones M1 and 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)). 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 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 uttered by the speaker H in front of the microphones M1 and M2, the amplitude of the sound signal Y21 of the microphone M2 whose sound collection surface is arranged toward the speaker H is larger than the amplitude of the output Y11 of the microphone M1. growing. 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 sound collection surface of the microphone M2 is directed in the same direction as the output of the speaker SP, the acoustic coupling between the speaker SP and the microphone M2 is reduced, and the microphone M2 is a speaker. It becomes difficult to collect the sound emitted by the SP, and the microphone M2 can be disposed in the vicinity of the speaker SP, that is, in the vicinity of the front air chamber Bf, so that the communication device A can be reduced in size.

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

  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.

  Furthermore, in the present embodiment, a cylindrical port 40 is provided so as to protrude from the front surface of the body A10 facing the diaphragm 23 of the speaker SP, and the front air chamber Bf communicates with the outside of the housing A1 via the port 40. By providing this port 40, the lowest resonance frequency of the speaker SP shifts to the low frequency side. Furthermore, by setting the resonance frequency of the port 40 to be lower than the lowest resonance frequency of the speaker SP, sound near the lowest resonance frequency of the speaker SP can be efficiently emitted. Therefore, since the sound pressure level of the speaker SP in the low frequency region increases, the sound quality and efficiency of the speaker SP are improved.

For example, when a hermetic housing without the port 40 is used, the lowest resonance frequency fo ′ of the speaker is generally equal to the equivalent mass (diaphragm, coil, air added mass) Mo of the vibration system of the speaker. It depends on the stiffness So of the supporting edge etc. and the stiffness Sc of the air in the rear air chamber Br,
fo ′ = {1 / (2π)} · √ {(So + Sc) / Mo}
It is represented by

The stiffness Sc of the air in the rear air chamber Br is defined as follows. The capacity of the rear air chamber Br is V, the air density is ρ, the effective area of the diaphragm 23 of the speaker SP is D, and the sound velocity is Cv.
Sc = ρCv ² D / V
The stiffness Sc is inversely proportional to the capacity V of the rear air chamber Br. Therefore, if the capacity V of the rear air chamber Br is small, the stiffness Sc is increased and the resonance frequency fo is increased.

  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 a plurality of sound holes are formed in the front surface. Each result is shown for both the case where the sealed housing is used and the case where an ideal baffle plate is used as the housing.

  First, the ideal baffle plate is a baffle plate C having an infinite size as shown in FIG. 15, and the speaker SP and the microphone substrate MB1 are attached to the baffle plate C and the baffle facing the speaker SP is provided. The cancellation amount (characteristic Y1a in FIG. 13) when the sound hole 12 is formed in the front surface of the plate C maintains 10 dB or more in the frequency band 100 Hz to 10000 Hz, and the radiation sound pressure characteristic (characteristic Y2a in FIG. 14) is The lowest resonance frequency fo′1 of the speaker SP is 600 Hz, and the lowest resonance frequency shows the same ideal characteristic as that of the speaker SP alone. 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 amount of cancellation (characteristic Y1b in FIG. 13) when using a sealed housing is also maintained at 10 dB or more in the frequency band of 100 Hz to 10000 Hz, and is substantially the same as when using the baffle plate C. 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 Sc of the rear air chamber Br becomes large, the minimum 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 sealed housing having the same capacity as the rear air chamber Br of the housing A1 is the lowest resonance frequency fo′2 = 1200 Hz of the speaker SP. Compared to the case where 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 SP are deteriorating. The radiated sound pressure characteristic (characteristic Y2c in FIG. 14) when using a sealed housing having a capacity three times that of the rear air chamber Br of the housing A1 is the lowest resonance frequency fo′3 = 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, when the capacity of the rear air chamber Br is increased, the housing becomes larger and it is difficult to reduce the size of the communication device.

On the other hand, when the housing A1 of the present embodiment including the port 40 is used, an equivalent mass Mp of the port 40 based on the shape such as the diameter and length of the port 40 is generated, and the lowest resonance frequency fo of the speaker is
fo = {1 / (2π)} · √ {(So + Sc) / (Mo + Mp)}
It is represented by Therefore, by providing the port 40 in the housing A1, the lowest resonance frequency fo of the speaker is lower than the lowest resonance frequency fo ′ of the sealed speaker by the equivalent mass Mp of the port 40. Furthermore, the resonance frequency of the port 40 and a sound having a frequency slightly higher than the resonance frequency are strengthened and output forward from the port 40, and the sound pressure level increases. That is, if the lowest resonance frequency of the speaker SP is shifted to the low frequency side (for example, about 700 Hz) by providing the port 40, and further the resonance frequency of the port 40 is set to be lower than the lowest resonance frequency of the speaker SP, The sound quality and efficiency of the speaker SP can be improved. Therefore, in this embodiment, by providing the port 40 in the front air chamber Bf in the small-capacity rear air chamber Br, the sound quality and efficiency of the speaker SP are improved while reducing the size of the communication device.

Further, as shown in FIG. 16, the frequency characteristic of the radiated sound pressure in front of the communication device A is a band pass characteristic having a high sound pressure level between the lowest resonance frequency fo and the second resonance frequency fh of the speaker. have. Here, the second resonance frequency fh is defined as Sd as the stiffness of the air in the front air chamber Bf.
fh = {1 / (2π)} · √ {(So + Sc + Sd) / Mo}
It becomes a value higher than the lowest resonance frequency fo. Therefore, the lowest resonance frequency fo of the speaker is higher than the lowest resonance frequency fo′1 (= 600 Hz) of the speaker attached to the baffle plate C and lower than 1 KHz, and the second resonance frequency fh is higher than 1 KHz. By setting the shape of the volume of the front air chamber Bf, the capacity of the rear air chamber Br, the diameter of the port 40, the length, and the like so as to be higher and lower than 3 KHz, the call voice band (for example, 600 Hz to 3KHz) call quality is improved.

Note that the sound radiated forward from the speaker SP is output to the outside only through the port 40 and can be regarded as a point sound source. When the microphones M1 and M2 collect the sound emitted from the speaker SP, The delay time Td generated between the outputs of the microphones M1 and M2 is ideally constant with respect to the frequency without depending on the frequency of the sound emitted from the speaker SP. (However, since it is not actually an ideal condition (for example, there is no variation in the point sound source, the sealed housing structure, the CR of the circuit configuration, etc.), it depends on the frequency of the sound emitted by the speaker SP.)
(Embodiment 2)
In the first embodiment, the output direction of the speaker SP and the axial direction of the port 40 are the same direction (forward direction). However, in this embodiment, as shown in the schematic diagram of FIG. 17, the sub baffle A20 in the housing A2 The output direction of the attached speaker SP is the downward direction (or upward direction), and the port 41 is formed in the front-rear direction so as to protrude into the inside of the housing A2. Thus, it is possible to improve the sound quality and efficiency of the speaker SP.

(Embodiment 3)
An example of a wiring system using the communication device of the present invention will be described below.

  First, as shown in FIG. 18, one or a plurality of switch boxes 82 embedded and disposed at 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 82 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. 19) to which three large-angle, single-module embedded wiring devices standardized by JIS, for example, can be mounted. As shown in FIG. 20, 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. 20, and the other switch box 82 is introduced from the lower part. The power line Lp and the 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. 19, the mounting frame 84 is provided with a window hole 84a for mounting an instrument at the center, and the front part of the instrument body to be mounted is fitted from the back to the window hole 84a. 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. 20, 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 As shown in FIG. 19, a modular connection port CN1 having a connection port CN1B is provided.

  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. 21 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. A plurality of types of basic function modules 90 are prepared depending on functions, and the synthetic resin shown in FIG. 21 and FIG. A circuit (corresponding to each function) is built in a flat module body 90a made of a 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 82 in Rukoto.

  Further, on the front surface of the module main body 90a, at a position above or below the opening position of the upper and lower mounting holes 90b, as shown in FIG. 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 portion 93 on the left or right side of the partition wall 94, one half of the synthetic resin connector 100 shown in FIG. 22B is fitted to a position where it contacts the partition wall 94, and the other half of the connector 100 is illustrated. 23, 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 side, and in the extended function module 91, the lid 91a is closed so as to be fitted over the connecting groove 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 CN3A, CN3A ′ and information connectors CN3B, CN3B ′ are standardized as a system in the arrangement of the internal contact portions, the shape of the opening, and the information on the power connector disposed on the same surface. 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 portion CN2A into an operating power supply for the internal circuit composed of a stable DC voltage, and commercial power via the power connectors CN3A 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 the functions.

  Next, in the wiring system of the present embodiment, a plurality of types of extended function modules 91 are prepared according to functions that operate 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. 24A, 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 extension 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. 24C). )reference).

  If the basic function module 90 and the extended function module 91 are provided with the same configuration as that of the communication device according to the first or second embodiment, a communication device that achieves prevention of howling, downsizing, sound quality, and efficiency in the wiring system can be obtained. Can be configured.

  FIG. 25 shows a basic function module 90A (hereinafter referred to as a telephone call) in which the module main body 90a includes the speaker SP, the microphone board MB1, the sound processing unit 10, the front air chamber Bf, the rear air chamber Br, and the like as in the communication device of the first embodiment. A port 40 is formed on the front surface of the module main body 90a so as to face the diaphragm of the speaker SP, 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.

  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. 26 shows an extended function module 91A (hereinafter referred to as a telephone call) in which the module main body 91a includes the speaker SP, the microphone board MB1, the sound processing unit 10, the front air chamber Bf, the rear air chamber Br, and the like as in the communication device of the first embodiment. One port 40 is formed on the front surface of the module main body 91a so as to face the diaphragm of the speaker SP, 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.

  Further, the basic function module 90 and the extended function module 91 are prepared in a plurality of types depending on the function. For example, as shown in FIG. 18, one or more switch boxes 82 are embedded and arranged 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, an information signal is exchanged between the corresponding basic function module 90 and the extended function module 91. An intercom system is configured with the other telephone device, enabling communication between the two and performing alarm notification.

It is side surface sectional drawing which shows the structure of the communication apparatus of Embodiment 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 conventional cancellation amount by a signal processing part. It is a figure which shows the radiation sound pressure characteristic of the conventional speaker. It is a partial side sectional view showing the composition at the time of using an ideal baffle board. It is a figure which shows the radiation sound pressure characteristic of the speaker of Embodiment 1. FIG. FIG. 3 is a side cross-sectional view illustrating a schematic configuration of a communication device according to a second embodiment. It is a block diagram of the wiring system using the communication apparatus of Embodiment 3. 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 port

Claims (4)

A housing;
A speaker that is disposed in the housing and outputs audio information transmitted from the outside 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 audio signal to the outside;
And a port for communicating the front air chamber to the outside of the housing.   2. The communication device according to claim 1, wherein the rear air chamber is a space sealed between an inner surface of the housing and the other surface side of the speaker.   The communication device according to claim 1, wherein the first microphone is disposed to face a diaphragm of the speaker.   The lowest resonance frequency of the speaker is higher than the lowest resonance frequency of the speaker attached to the baffle plate having an infinite size and lower than 1 KHz, and the other resonance frequency of the speaker is higher than 1 KHz and lower than 3 KHz. 4. The communication device according to claim 1, wherein each volume of the front air chamber and the rear air chamber and a shape of the port are set so as to have a frequency.

Images