JP4949111B2 - Silencer unit - Google Patents

Description

  The present invention relates to a silencing unit, and more particularly to a silencing unit for silencing driving sound generated from a target device such as a vending machine.

  Usually, a vending machine that accommodates merchandise such as beverages is provided with a cooling device for cooling the merchandise. This cooling device generally includes a cooler for cooling the air in the machine, a compressor for compressing refrigerant supplied to the cooler, a condenser for liquefying the compressed refrigerant, and a compressor or condenser. A fan that is rotationally driven to cool the air is provided.

  In the casing of this type of vending machine, for example, a merchandise accommodating portion for accommodating merchandise is formed from the central portion to the upper portion, and the cooling device is disposed in the lower portion in the casing. Normally, the lower part of the housing has an air inlet on the front and an air outlet on the back. When the blower is driven, air outside the machine is sucked in from the air inlet and around the compressor and condenser. Through the exhaust port.

  Although such air intakes and exhausts are indispensable for circulating outside air into the machine, the driving sound generated from the various components provided in the casing as described above is There was a problem of leakage from the mouth. Therefore, when such a vending machine is installed indoors in a quiet place such as a hotel or a hospital, the problem of noise may become serious.

In order to solve such a problem, conventionally, a technique has been proposed in which a drive sound is prevented from leaking from within the apparatus by providing a muffling member (for example, Patent Document 1).
JP 2003-281613 A

  However, when the muffling member is used, although a sound with a high frequency can be satisfactorily muffled, there is a problem that it is difficult to mute a sound with a low frequency. In particular, the drive sound generated from the compressor or the blower has a relatively low frequency, and there are cases where the sound cannot be sufficiently silenced even if a silencer member is used. Therefore, it is conceivable to provide a silencer in the casing of the vending machine to mute the drive sound generated in the casing. However, in existing vending machines, it is possible to secure a space for installing the silencer in the casing. Since it is difficult, it is necessary to form the vending machine provided with the silencer separately and replace the existing vending machine.

  The present invention has been made in view of the above circumstances, and provides a mute unit that can be applied to an existing target device and can effectively mute drive sound generated by the target device. For the purpose.

  A silencing unit according to a first aspect of the present invention is a silencing unit for silencing drive sound of a target device that is installed at an interval above the installation surface via legs, the target device and the target device. A main body arranged in a space formed between the installation surface, a microphone provided on the front surface or the back surface of the main body, to which driving sound generated by the target device is input, and an input signal from the microphone A sound signal generating means for generating a sound signal based on the sound signal, and a speaker provided on the front or back of the main body and outputting a sound based on the sound signal generated by the sound signal generating means. The means is configured to generate a sound signal so that a sound from the speaker input to the microphone has an opposite phase to the driving sound input to the microphone.

  According to such a configuration, the sound signal is generated so that the sound from the speaker input to the microphone is in an opposite phase to the drive sound generated by the target device input to the microphone, whereby the speaker Can be made to interfere with the driving sound, and the driving sound can be muted. That is, the sound output from the speaker has an opposite phase to the drive sound generated by the target device at the position reaching the microphone, and the drive sound is muted by sound wave interference. Accordingly, the drive sound generated by the target device using the silencer member or the like is not passively silenced, but the drive sound can be silenced by actively generating a sound having a phase corresponding to the drive sound. . In this way, by adopting a configuration that silences the drive sound using sound wave interference, unlike the configuration that uses the silencer member, the drive sound generated by the target device can be effectively silenced. it can.

  In addition, since the main body can be installed in a relatively low space formed between the target device and the installation surface, it can be applied to an existing target device and generated by the target device. The drive sound can be effectively silenced.

  The silencer unit according to the second aspect of the present invention is configured by including two or more speakers in addition to the above configuration. According to such a configuration, sound can be output in a wider range from two or more speakers, and the sound can be made to interfere with the drive sound generated by the target device. Can be muted.

  In addition to the above configuration, the silencer unit according to the third aspect of the present invention is configured such that the distances between the two or more speakers and the microphone are the same. According to such a configuration, since the distance between each speaker and the microphone can be made the same, the same sound is output from each speaker and interfered with the drive sound generated by the target device, thereby driving the drive. Sound can be muted well. Thereby, the process which the sound signal production | generation means produces | generates the sound signal output to each speaker can be simplified.

  A silencer unit according to a fourth aspect of the present invention is configured such that, in addition to the above configuration, the two or more speakers are symmetrically arranged on the left and right with the microphone interposed therebetween. According to such a configuration, by outputting sound from two or more speakers provided on the left and right across the microphone, the sound is output from the speakers in a wider range in the left-right direction, and the sound is output from the target device. Since it can be made to interfere with the generated drive sound, the drive sound can be silenced more effectively.

  A silencer unit according to a fifth aspect of the present invention includes, in addition to the above-described configuration, the microphone and the speaker are provided on the front surface and the back surface of the main body, and includes an expansion / contraction mechanism that expands and contracts the main body in the front-rear direction. Is done. According to such a configuration, by expanding and contracting the main body using the expansion / contraction mechanism, the front surface of the main body can be aligned with the front surface of the target device, and the back surface of the main body can be aligned with the back surface of the target device. As a result, the influence of the reflected wave generated at the inner and outer boundaries of the space formed between the target device and the installation surface is suppressed, and the sound from the speakers respectively provided on the front surface and the back surface of the main body is generated by the target device. The drive sound can be satisfactorily interfered with the drive sound, and the drive sound can be silenced more effectively.

  According to the present invention, the sound signal from the speaker is generated by generating the sound signal so that the sound from the speaker input to the microphone has an opposite phase to the drive sound generated by the target device input to the microphone. Since the sound can be made to interfere with the drive sound and the drive sound can be silenced, the drive sound generated by the target device can be effectively silenced. In addition, by installing the main body in a relatively low space formed between the target device and the installation surface, it can be applied to the existing target device, and the drive sound generated by the target device Can be effectively silenced.

  FIG. 1 is a perspective view showing an example of the configuration of a silencer unit 100 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the muffler unit 100 of FIG. In the following, the left side in FIG. 2 will be described as the front, the right side as the rear, the near side as the right side, and the back side as the left side. The muffler unit 100 is configured by a microphone body 102A, 102B, speakers 103A, 103B, and a control device 104 being integrally held by a hollow main body 101.

  The main body 101 includes a first housing 110 disposed on the front side, a second housing 120 disposed on the rear side, and a connecting member 130 that connects the first housing 110 and the second housing 120. Consists of. The first housing 110 is a hollow member having a thin rectangular parallelepiped shape whose left and right widths are larger than the upper and lower thicknesses, and whose back surface is open. The second housing 120 is a hollow member having a thin rectangular parallelepiped shape in which the left and right widths are larger than the upper and lower thicknesses, like the first housing 110, and the front surface thereof is open. The first casing 110 and the second casing 120 are formed such that the left and right widths and the upper and lower thicknesses match each other.

  The connecting member 130 is formed of a cylindrical member having a front end portion coupled to the back surface of the first housing 110 and a rear end portion coupled to the front surface of the second housing 120. It can be expanded and contracted in the direction. The connecting member 130 constitutes an expansion / contraction mechanism, and the main body 101 is moved in the front-rear direction by changing the distance in the front-rear direction between the first housing 110 and the second housing 120 by extending / contracting the connection member 130. It can be expanded and contracted.

  In addition, the connection member 130 communicates the open back surface of the first housing 110 and the front surface of the second housing 120 with each other so that the connection member 130 is connected to the inside of the main body 101 together with the first housing 110 and the second housing 120. A closed space is formed. With such a configuration, an enclosure for the speakers 103A and 103B is formed by the main body 101, and a low frequency sound can be favorably output from the speakers 103A and 103B. The connecting member 130 is preferably formed of an elastic body such as rubber.

  On the front surface of the first housing 110, one microphone 102A and two speakers 103A are provided in a straight line in the left-right direction. More specifically, a microphone 102A is provided at the center in the left-right direction on the front surface of the first housing 110, and speakers 103A are provided at both left and right ends of the front surface across the microphone 102A. Thereby, the two speakers 103A are symmetrically arranged on the left and right with respect to the microphone 102A. Note that the two speakers 103 </ b> A attached to the front surface of the first housing 110 are attached toward the front. In addition, the microphone 102A attached to the front surface of the first housing 110 is configured so that sound is input from the front by opening the front.

  On the back surface of the second housing 120, one microphone 102 </ b> B and two speakers 103 </ b> B are provided in a straight line in the left-right direction in the same manner as the front surface of the first housing 110. That is, a microphone 102B is provided at the center in the left-right direction on the back surface of the second housing 120, and speakers 103B are provided at both left and right ends of the back surface with the microphone 102B interposed therebetween. Accordingly, the two speakers 103B are arranged symmetrically on the left and right with respect to the microphone 102B. Note that the two speakers 103B attached to the back surface of the second housing 120 are attached to the rear. In addition, the microphone 102B attached to the back surface of the second housing 120 is configured such that sound is input from the rear side by opening the rear side.

  The control device 104 constitutes sound signal generation means for generating a sound signal based on the input signals from the microphones 102A and 102B, and the sound based on the sound signal generated by the control device 104 is output from the speakers 103A and 103B. Is done. The control device 104 generates a sound signal output from the two front speakers 103A based on the input signal from the front microphone 102A, and from the two rear speakers 103B based on the input signal from the rear microphone 102B. Generate a sound signal to be output. The control device 104 is provided in the main body 101, for example, in the first housing 110 or the second housing 120. In this example, the control device 104 is provided in the first housing 110, but the configuration is not limited to this, and a configuration in which the control device 104 is provided in the second housing 120 may be used.

  FIG. 3 is a diagram showing an installation mode of the muffler unit 100 of FIG. 1, (a) is a front view showing an example of the vending machine 1 in which the muffler unit 100 is installed, and (b) is the vending machine. 1 shows a side view of FIG. FIG. 4 is a front view showing a state in which the open / close door 3 of the vending machine 1 of FIG. 3 is opened, and the silencing unit 100 is omitted. FIG. 5 is a schematic sectional side view of the vending machine 1 shown in FIG. 3, in which the silencing unit 100 is omitted. This vending machine 1 is a vending machine that sells beverages and the like enclosed in cans as commodities, and stores a large number of commodities in a casing 2 having a vertically long rectangular parallelepiped shape. In the following, the left side in FIG. 3B will be described as the front, the right side as the rear, the near side as the right side, and the back side as the left side.

  A front opening 2 </ b> A that opens the entire front surface is formed on the front surface of the housing 2, and the front opening 2 </ b> A is covered with an opening / closing door 3 that is attached to the housing 2 so as to be opened and closed. That is, the open / close door 3 forms the front surface of the housing 2 in a closed state. Legs 4 are attached to the four corners on the bottom surface of the housing 2. These leg portions 4 are screwed into the bottom surface of the housing 2 so as to be able to advance and retract in the vertical direction. When installing the vending machine 1, the height of the housing 2 relative to the ground is adjusted by adjusting the screwing amount of each leg 4 to the housing 2 and grounding the bottom surface of each leg 4. be able to.

  As described above, the casing 2 of the vending machine 1 is installed with a space above the installation surface 200 via the legs 4, and between the bottom surface of the casing 2 and the installation surface 200. A predetermined space S is formed. The height of the space S changes by adjusting the screwing amount of each leg 4 with respect to the housing 2, but is usually much lower than the left and right widths of the housing 2, and the space S narrow in the vertical direction. Is formed. More specifically, the space S has a height of about 5 to 10 cm, a left and right width of about 1 m, and a ratio of the height to the left and right width is 1/10 or less.

  In the present embodiment, the silencing unit 100 is disposed in the space S, and the driving sound generated by the vending machine 1 as the target device can be muted by the silencing unit 100. As described above, the silencing unit 100 includes the thin main body 101 whose left and right widths are larger than the upper and lower thicknesses, so even in the space S with a low height formed at the bottom of the vending machine 1. As shown in FIG. 1, it can arrange | position favorably. In addition, the thickness of the main body 101 of the muffler unit 100 is formed to be about 5 to 10 cm so as to be accommodated in the space S.

  In the center of the front surface of the open / close door 3, a money insertion area 5 is formed that is used when a user who wants to purchase goods inserts money. In this money insertion area 5, a coin insertion slot 5A for inserting coins, a bill insertion slot 5B for inserting banknotes, and a return lever 5C for instructing the return of the inserted coins are inserted. And an input amount display portion 5D for displaying the total amount of money. When the return lever 5C is operated after the coin is inserted, the bill is returned from the bill input port 5B, and the coin is returned from the coin return port 6 formed in the lower part of the open / close door 3.

  A display area 7 on which samples of products that can be sold by the vending machine 1 are displayed is formed in the upper front portion of the open / close door 3. This display area 7 is provided with a purchase button 7A associated with each sample displayed, and after the user inserts money from the coin insertion slot 5A or the bill insertion slot 5B, By operating the purchase button 7A, it is possible to instruct purchase of a product corresponding to the purchase button 7A. The product for which purchase is instructed is sent out to the lower part in the housing 2 and can be taken out from a horizontally long product outlet 8 formed in the lower part of the door 3. In addition, when the amount of the product instructed to be purchased is lower than the input amount, the change corresponding to the difference is returned from the coin return slot 6.

  A money processing unit 9 is provided at a position corresponding to the back side of the money insertion area 5 on the front side of the central portion of the rear surface of the open / close door 3. The money handling unit 9 stores a money inserted from the coin insertion slot 5A and the bill insertion slot 5B, and performs a process for returning the money from the coin return slot 6 or the bill insertion slot 5B as necessary. It is. A control unit 10 is provided on the side of the money handling unit 9 in the center of the back of the open / close door 3, and the operation of the vending machine 1 is controlled by a processor provided in the control unit 10. ing.

  In the housing 2, a product storage portion 11 for storing products is formed in a region extending from the center to the top, and a cooling device 12 for cooling the products in the product storage portion 11 is provided in the housing 2. Located at the bottom inside. The product storage unit 11 is formed by arranging a cooling product storage unit 11 </ b> A and a heated product storage unit 11 </ b> B each having a vertically long shape side by side. A cooler 13 for cooling the air in the cooled product housing portion 11A is disposed below the cooled product housing portion 11A. On the other hand, the heater 14 for heating the air in the said heated goods accommodating part 11B is arrange | positioned under the heated goods accommodating part 11B. A product discharge port 15 for discharging a product from the product storage unit 11 to the product outlet 8 side is formed on the front side in the casing 2. A plurality of product discharge ports 15 are formed, and each product discharge port 15 is associated with the cooled product storage unit 11A or the heated product storage unit 11B.

  The cooling device 12 is for cooling the product accommodated in the cooled product accommodating portion 11A. In addition to the cooler 13, the compressor 16 that compresses the refrigerant supplied to the cooler 13 is compressed. A condenser 17 that liquefies the refrigerant and a blower 18 that is rotationally driven to cool the compressor 16 and the condenser 17 are provided. The compressor 16 is rotationally driven by an AC motor to which an AC voltage is supplied. On the other hand, the blower 18 is rotationally driven by a DC motor to which a DC voltage is supplied.

  The cooler 13, the compressor 16, and the condenser 17 communicate with each other via piping, and cool the air in the cooled product accommodating portion 11 </ b> A via the cooler 13 by circulating the refrigerant through these portions. can do. More specifically, when the cooling device 12 is driven, the refrigerant is compressed by the compressor 16 to become high-pressure gas, and is then liquefied by being cooled by the condenser 17. Then, the liquefied refrigerant is decompressed and evaporated in the cooler 13, whereby the cooler 13 is cooled by so-called latent heat of vaporization. The liquefied refrigerant is compressed again by the compressor 16 and circulated to the condenser 17 and the cooler 13.

  At the bottom of the open / close door 3, a horizontally long intake port 19 is formed in which both end portions are located in the vicinity of both left and right end portions of the open / close door 3. On the other hand, a horizontally long exhaust port 20 is formed at the bottom of the rear surface of the housing 2 so that at least a part thereof faces the intake port 19 in the front-rear direction. A partition plate 21 is provided below the product storage portion 11 in the housing 2, and a region below the partition plate 21 has an intake port 19 and an exhaust port 20 as openings, and the inside of the housing 2. A duct-like space 22 penetrating in the front-rear direction is formed.

  Among the components of the cooling device 12, the condenser 17, the blower 18, and the compressor 16 are disposed in the duct-like space 22. More specifically, the condenser 17, the blower 18, and the compressor 16 are arranged in this order in the front-rear direction at the bottom of the housing 2. Thereby, the condenser 17, the blower 18, and the compressor 16 are opposed to the intake port 19 and the exhaust port 20 in the front-rear direction, respectively. On the other hand, the cooler 13 is disposed above the duct-shaped space 22.

  When the cooling device 12 is driven, the blower 18 is driven to rotate, so that air outside the machine is sent into the machine through the air inlet 19. The air sent into the machine passes around the condenser 17 and the compressor 16 in the duct-like space 22 and is sent out of the machine through the exhaust port 20, whereby the condenser 17 and the compressor 16 are cooled. The

  The drive sound generated from the cooling device 12 in the housing 2 leaks out of the machine forward from the air inlet 19 and leaks out of the machine rearward from the exhaust port 20. At this time, the drive sound leaked from the air inlet 19 is input to the microphone 102A provided on the front surface of the silencer unit 100, and the drive sound leaked from the exhaust port 20 is input to the microphone 102B provided on the back surface of the silencer unit 100. Entered.

  In the vending machine 1 according to the present embodiment, sound corresponding to the driving sound leaking from the air inlet 19 is output from the front speaker 103A, and the output sound from the speaker 103A is input to the input signal from the front microphone 102A. By performing feedback control based on this, the drive sound leaking from the air inlet 19 can be silenced by so-called active silencing. Similarly, in this vending machine 1, the sound corresponding to the drive sound leaking from the exhaust port 20 is output from the rear speaker 103B, and the output sound from the speaker 103B is based on the input signal from the rear microphone 102B. By performing feedback control, the drive sound leaking from the exhaust port 20 due to active silencing can be silenced.

  FIG. 6 is a schematic diagram for explaining the principle of active silencing performed by the silencing unit 100. Here, a case where the drive sound leaking from the intake port 19 is actively silenced using the front microphone 102A and the speaker 103A will be described. However, the drive sound leaking from the exhaust port 20 also uses the rear microphone 102A and the speaker 103A. The active mute can be performed on the same principle.

  Driving sound generated from the compressor 16 and the blower 18 arranged in the duct-shaped space 22 travels in the duct-shaped space 22 in the front-rear direction. The driving sound traveling forward in the duct-like space 22 is directed to the outside of the machine from the air inlet 19 as indicated by an arrow in the figure, and is provided on the front surface of the silencer unit 100 via the space outside the machine. Input to the microphone 102A.

  The control device 104 provided in the muffling unit 100 is provided with a phase adjustment amplifier circuit 104A as sound signal generation means for generating a sound signal based on an input signal from the microphone 102A. Sounds based on the sound signal generated by the phase adjustment amplifier circuit 104A are output at the same volume from the two speakers 103A provided on the front surface of the silencer unit 100, and the sound is output from the microphone 102A via a space outside the apparatus. Is input.

  The phase adjustment amplifier circuit 104A performs feedback control by performing processing for shifting the phase of a signal at a specific frequency and processing for increasing amplitude based on the signal input from the microphone 102A. More specifically, by removing the input signal corresponding to the output sound from the speaker 103A from the input signal from the microphone 102A, the input signal corresponding to the driving sound leaked from the intake port 19 is extracted. . Then, the phase of the input signal corresponding to the driving sound of the specific frequency is adjusted so that the sound from the speaker 103A input to the microphone 102A has an opposite phase, and from the speaker 103A input to the microphone 102A. The amplitude of the sound is increased so as to have the same amplitude.

Here, when sound is generated in the duct-shaped space 22, a one-dimensional sound field is formed in the duct-shaped space 22. In such a one-dimensional sound field, the sound wave propagating in the duct-like space 22 can be regarded as a plane wave when a condition such as the following expression (1) is satisfied, and is excellent by superposition of plane waves having opposite phases. Can be silenced.
d << λ / 2 Formula (1)
d: inner diameter of duct λ: wavelength of sound

  Since the compressor 16 is driven by an AC motor, the driving sound of the compressor 16 peaks at different frequencies depending on the frequency of the supplied AC commercial power. More specifically, the driving sound of the compressor 16 has a peak at a frequency n times (n is a natural number) with respect to the frequency of the AC commercial power supply. Among the driving sounds generated from the compressor 16, the driving sounds tend to be particularly harsh at the relatively low frequencies of n = 1 and n = 2. That is, the compressor 16 generates an unpleasant driving sound in the range of about 50 to 120 Hz.

  On the other hand, since the blower 18 is driven by a DC motor, a driving sound peak occurs at a specific frequency. Specifically, the driving sound of the blower 18 depends on the number of blades provided in the blower 18 and the number of rotations. In the present embodiment, a peak is generated at about 140 Hz. In this way, the drive sound from the blower 18 that has a peak at a relatively low frequency tends to be particularly disturbing compared to the drive sound from other components other than the compressor 16. Moreover, when the peak of the frequency of the drive sound each generate | occur | produced from the compressor 16 and the air blower 18 is adjoining like this Embodiment, there exists a tendency for a drive sound to be heard more harshly.

  As described above, the annoying driving sound generated from the compressor 16 and the blower 18 is distributed in a frequency band of about 50 to 140 Hz. The sound wavelength λ corresponding to such a frequency band is about 2.4 to 6.8 m. On the other hand, the inner diameter d of the duct-shaped space 22 is several tens of centimeters. These numerical values satisfy the condition of the above formula (1), and the sound waves from the compressor 16 and the blower 18 propagating in the duct-like space 22 can be regarded as plane waves. Thus, the drive sound from the compressor 16 and the blower 18 can be silenced satisfactorily.

  FIG. 7 is a waveform diagram for explaining a mode in which the driving sound is silenced by superimposing antiphase plane waves. FIG. 7A is a driving sound from the compressor 16 or the blower 18 input to the microphones 102A and 102B. (B) shows the waveform of the sound from the speakers 103A and 103B input to the microphones 102A and 102B, and (c) shows the waveform of the synthesized wave of these sounds. Here, the drive sound generated from the compressor 16 or the blower 18 leaks outside the machine via the intake port 19 or the exhaust port 20 and is input to the microphones 102A and 102B in the waveform as shown in FIG. The

  On the other hand, as shown in FIG. 7B, the sound output from the speakers 103A and 103B is opposite to the drive sound of a specific frequency from the compressor 16 or the blower 18 when input to the microphones 102A and 102B. It becomes a phase. Therefore, the drive sound of the specific frequency from the compressor 16 or the blower 18 and the sound output from the speakers 103A and 103B are superimposed on each other when input to the microphones 102A and 102B as shown in FIG. To cancel each other, and the drive sound of the frequency is muted.

  In the present embodiment, the sound from the speakers 103A and 103B input to the microphones 102A and 102B is opposite in phase to the drive sound generated by the vending machine 1 input to the microphones 102A and 102B. By generating the sound signal, it is possible to cause the sound from the speakers 103A and 103B to interfere with the drive sound and to mute the drive sound. That is, the sound output from the speakers 103A and 103B has an opposite phase to the driving sound generated by the vending machine 1 at the position reaching the microphones 102A and 102B, and the driving sound is muted by sound wave interference. Accordingly, the drive sound generated by the vending machine 1 is not passively silenced by using a silencer member or the like, but the drive sound is silenced by actively generating a sound having a phase corresponding to the drive sound. Can do. In this way, by adopting a configuration in which the driving sound is silenced using sound wave interference, unlike the configuration in which the silencing member is used, the driving sound generated by the vending machine 1 is effectively silenced. be able to.

  In particular, by outputting sound from the two speakers 103A and 103B provided on the left and right sides of the microphones 102A and 102B, the sound is output from the speakers 103A and 103B in a wider range in the left and right directions, and the sound is automatically sold. Since it can be made to interfere with the drive sound produced | generated by the apparatus 1, the said drive sound can be silenced more effectively.

  Further, by providing the microphones 102A and 102B and the two speakers 103A and 103B so as to be aligned in the left-right direction with respect to the front and back of the main body 101 whose left and right widths are larger than the upper and lower thicknesses, the upper and lower thicknesses are provided. Therefore, it is possible to configure a thin silencer unit 100 having a small size. Since such a muffler unit 100 can be installed in a relatively low space S formed between the vending machine 1 and the installation surface 200, it can be applied to the existing vending machine 1. The drive sound generated by the vending machine 1 can be effectively silenced.

  In the present embodiment, since the two speakers 103A and 103B are symmetrically arranged on the left and right with respect to the microphones 102A and 102B, the distances between the speakers 103A and 103B and the microphones 102A and 102B can be the same. it can. Therefore, by outputting the same sound from each of the speakers 103A and 103B and causing it to interfere with the driving sound generated by the vending machine 1, the driving sound can be satisfactorily silenced. Thereby, the process which produces | generates the sound signal which 104 A of phase adjustment amplifier circuits output to each speaker 103A, 103B can be simplified.

  Furthermore, in the present embodiment, the front surface of the main body 101 is aligned with the front surface of the vending machine 1 by expanding and contracting the main body 101 using the connecting member 130, and the rear surface of the main body 101 is aligned with the rear surface of the vending machine 1. be able to. Usually, when a sound wave passes from a narrow space such as the space S to a wide space in front of or behind the vending machine 1, the impedance becomes discontinuous at the boundary, and the reflected wave in the direction opposite to the traveling direction. Occurs. Therefore, if the front surface and the back surface of the main body 101 are aligned with the front surface and the back surface of the vending machine 1 by expanding and contracting the connecting member 130, the inside and outside of the space S formed between the vending machine 1 and the installation surface 200 will be described. The influence of the reflected wave generated at the boundary is suppressed, the sound from the speakers 103A and 103B provided on the front surface and the back surface of the main body 101 is made to interfere well with the drive sound generated by the vending machine 1, and the drive sound is It can mute more effectively.

  In the above embodiment, the configuration in which the microphones 102A and 102B and the speakers 103A and 103B are provided on both the front surface and the back surface of the main body 101 of the muffling unit 100 has been described. The structure provided only in one of the front surface or back surface of this may be sufficient.

  Further, the present invention is not limited to the configuration in which one microphone 102A, 102B and two speakers 103A, 103B are provided on the front surface or the back surface of the main body 101 of the silencer unit 100. For example, a configuration in which three microphones and two speakers are provided. It may be. In this case, it is preferable that the microphone and the speaker are alternately arranged, and it is more preferable that the distance between the microphone and the speaker is equal. If these microphones and speakers are symmetrically arranged in the left-right direction, the drive sound from the vending machine 1 can be muted equally on the left and right, so that the drive sound can be muted more satisfactorily. Note that the microphone and the speaker are not limited to be arranged in a straight line in the left-right direction, but may be arranged in a direction inclined with respect to the left-right direction, and two or more speakers are provided. In such a case, the microphone may be provided at a position shifted from a straight line connecting the speakers. Moreover, the structure which provided only one speaker may be sufficient.

  Furthermore, although the above embodiment demonstrated the case where the muffling unit 100 was applied to the vending machine 1, it is not restricted to such a structure, The present invention is not limited to the vending machine 1 and is installed on the installation surface. On the other hand, as long as it is a target device that is installed at a distance upward via the legs, it can be applied to various target devices such as an air conditioner and a blower.

It is the perspective view which showed one structural example of the silencer unit by embodiment of this invention. It is AA sectional drawing of the silencer unit of FIG. It is the figure which showed the installation aspect of the silencing unit of FIG. 1, (a) is a front view which shows an example of the vending machine in which the silencing unit was installed, (b) has shown the side view of the said vending machine. . It is the front view which showed the state which opened the opening-and-closing door of the vending machine of FIG. 3, and has abbreviate | omitted the muffling unit. FIG. 4 is a schematic sectional side view of the vending machine in FIG. 3, omitting the silencing unit. It is a schematic diagram for demonstrating the principle of the active muffling performed by a muffling unit. It is a wave form diagram for explaining the mode which silences a drive sound by superposition of an antiphase plane wave, (a) is a waveform of a drive sound from a compressor or a fan inputted into a microphone, and (b) is a microphone. The waveform of the sound from the input speaker, (c) shows the waveform of the synthesized wave of these sounds.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vending machine 2 Case 4 Leg part 19 Intake port 20 Exhaust port 100 Silencer unit 101 Main body 102A, 102B Microphone 103A, 103B Speaker 104 Control apparatus 104A Phase adjustment amplifier circuit 110 First case 120 Second case 130 Connecting member 200 Installation surface S Space

Claims (5)

A silencing unit for silencing the drive sound of the target device installed at an interval above the installation surface via the legs,
A main body disposed in a space formed between the target device and the installation surface;
A microphone that is provided on the front surface or the back surface of the main body and that receives driving sound generated by the target device;
Sound signal generating means for generating a sound signal based on an input signal from the microphone;
A speaker that is provided on the front surface or the back surface of the main body and outputs a sound based on the sound signal generated by the sound signal generating means;
The sound signal generating means generates a sound signal so that the sound from the speaker input to the microphone has an opposite phase to the driving sound input to the microphone. .   The muffler unit according to claim 1, wherein two or more speakers are provided.   The silencer unit according to claim 2, wherein the distance between the two or more speakers and the microphone is the same.   The muffler unit according to claim 2, wherein the two or more speakers are symmetrically arranged on the left and right with the microphone interposed therebetween. The microphone and the speaker are provided on the front surface and the back surface of the main body, respectively.
The silencer unit according to claim 1, further comprising an expansion / contraction mechanism that expands / contracts the main body in the front-rear direction.

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