JP5979545B2 - Silencer - Google Patents

Description

  The present invention relates to a silencer.

  Conventionally, active noise control is used to reduce noise in a space where sound emitted by a noise source propagates, such as a range hood device, an electric device, an air conditioning duct, and a tunnel. Active noise control is a technique for actively reducing noise by radiating a cancellation sound having the opposite phase and the same amplitude of noise (see, for example, Patent Document 1).

JP-A-8-338224

  In active noise control, a microphone is installed in the space in order to detect noise in the space. A cancel sound is generated based on the noise signal collected by the microphone, and the cancel sound is output from a speaker provided in the space.

  However, if dirt such as oil or dust enters the space with time, the dirt adheres to the microphone or the speaker.

  Since the sensitivity and frequency characteristics of a microphone with dirt are changed, the phase and amplitude of the cancellation sound generated based on the collected noise signal are changed. In addition, the phase and amplitude of the canceling sound output from the speaker also change due to dirt adhering to the speaker. And the cancellation sound in which the phase and the amplitude have changed does not have the opposite phase and the same amplitude of the noise, and there is a possibility that the noise reduction effect by the active noise control is reduced.

  Therefore, the user needs to regularly clean the microphone and the speaker, but because the degree of dirt varies depending on the surrounding environment of the silencer, etc., it is difficult for the user to determine an appropriate cleaning timing.

  The present invention has been made in view of the above-described reasons, and an object thereof is to provide a silencer capable of appropriately notifying the user of the cleaning timing and maintaining the noise reduction effect by active noise control.

The silencer of the present invention is configured to output a sound emitted from the noise source on the basis of a first microphone provided in a space in which the sound emitted from the noise source propagates and the sound collected by the first microphone. A canceling sound generating unit that generates a canceling sound to be canceled; a speaker that outputs the canceling sound to the space; and a second sound that collects a synthesized sound of the sound emitted from the noise source and the canceling sound in the space. A control unit that controls the cancellation sound generation processing by the cancellation sound generation unit, the first microphone, and the second microphone so that the sound collected by the second microphone is reduced. And the frequency characteristics of the outputs of the first microphone and the second microphone, the degree of dirt on the speaker, and the first degree. A judgment table indicating at least one of the relationship of the relationship between the frequency characteristic of the output of the microphone and the second microphone, on the basis of the outputs of said first microphone and said second microphone in said judgment table A determination unit that determines at least one of the degree of contamination of each of the first microphone and the second microphone and the degree of contamination of the speaker, and a notification unit that performs a notification operation based on a determination result of the determination unit. It is characterized by that.

In the present invention, the determination table includes the relationship between the degree of contamination of the first microphone and the second microphone and the frequency characteristics of the outputs of the first microphone and the second microphone, and the contamination of the speaker. shows the relationship between the frequency characteristic of the output of the the degree first microphone and the second microphone, the determination unit, to said first microphone and said judgment table and the output of said second microphone Based on this, it is preferable to determine the degree of contamination of each of the first microphone, the second microphone, and the speaker.

  In this invention, it is preferable that the determination unit determines a cleaning location in the space according to the degree of contamination of the first microphone and the second microphone.

  In this invention, it is preferable that the noise source is a fan that sucks air from one side of the air passage forming the space to the other side.

In the aspect of the invention, the determination unit may be configured based on a result of each of the first microphone and the second microphone collecting the operation sound of the fan within a predetermined time after the fan starts operation. It is preferable to determine the degree of contamination of at least the first microphone and the second microphone.

  In the present invention, an evaluation sound reproducing unit that outputs an evaluation sound from the speaker is provided, and the determination unit at least based on a result of collecting the evaluation sound output from the speaker when the fan is stopped It is preferable to determine the degree of contamination of the first microphone and the second microphone.

  In this invention, it is preferable that the evaluation sound is a simulated sound of the operation sound of the fan.

  In the present invention, as described above, the cleaning timing is appropriately notified to the user, and each part after cleaning recovers its original performance, so that the noise reduction effect is also recovered. That is, according to the present invention, there is an effect that the cleaning timing can be appropriately notified to the user and the noise reduction effect by the active noise control can be maintained.

  Moreover, when the silencer of this invention is used for apparatuses provided with fans, such as a range hood apparatus, the cleaning timing of the fan of these apparatuses can also be notified to a user. Therefore, by cleaning the fan, it is possible to maintain the basic performance (intake amount, exhaust amount, etc.) of the fan, and it is also possible to maintain the function as a device having a fan such as a range hood device.

It is a block diagram which shows the structure of the silencer of Embodiment 1. It is the schematic which shows the structure of the range hood using the silencer same as the above. It is the schematic which shows the external appearance of the range hood using the silencer same as the above. It is a perspective view which shows the structure of a silencing unit same as the above. It is a wave form diagram which shows the outline of active noise control same as the above. It is a flowchart figure which shows a dirt detection process same as the above. (A) (b) It is a graph which shows the judgment table same as the above. It is a graph which shows another judgment table same as the above. It is a block diagram which shows the structure of the silencer of Embodiment 2. It is a flowchart figure which shows a dirt detection process same as the above. FIG. 10 is a flowchart illustrating a dirt detection process according to the third embodiment. It is a state transition diagram which shows a dirt detection process same as the above.

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

(Embodiment 1)
FIG. 1 shows a configuration of a silencer A of the present embodiment, and FIGS. 2 and 3 show an outline of a range hood device using the silencer A.

  As shown in FIG. 3, the range hood apparatus includes a hood 1 (ventilation path) disposed above a kitchen appliance in the kitchen. The hood 1 is formed in a box shape having an intake port 1a on the lower surface, and a fan 2 that takes in indoor air from the intake port 1a into the hood 1 and discharges it outside the hood 1 (see FIG. 2). Is provided. In addition, a filter 3 (see FIG. 2) covers the intake port 1 a, and a rectifying plate 4 is provided below the filter 3. The filter 3 filters oil, dust and the like entering the hood 1 from the intake port 1a. The rectifying plate 4 is formed slightly smaller than the intake port 1a and improves the intake efficiency. Note that the hood 1 constituting the ventilation path corresponds to the space of the present invention.

  When the fan 2 operates, the operation sound (noise) of the fan 2 propagates through the hood 1 and propagates from the intake port 1a to the room. Therefore, a silencer A is provided in the hood 1 in order to suppress noise transmitted to the room during the operation of the fan 2.

  As shown in FIGS. 1 and 2, the silencer A includes a reference microphone 11 (first microphone), an error microphone 12 (second microphone), a speaker 13, a notification unit 16, and a control block A1. The control block A1 is composed of a digital signal processor (DSP) or the like, and has functions of a mute control block 14 and a dirt detection block 15. This digital signal processor executes a program for realizing each function of the control block A1.

  As shown in FIG. 4, the reference microphone 11, the error microphone 12, the speaker 13, and the control block A <b> 1 are incorporated in the housing K to constitute a silencer unit U. The silencing unit U is detachably disposed in the air passage of the hood 1 (see FIG. 3).

  Moreover, the alerting | reporting part 16 is provided in the front surface of the food | hood 1 (refer FIG. 3), and performs alerting | reporting operation | movement with the alerting signal which the mute unit U output. The notification unit 16 may be configured by any of visual notification means such as lighting and flashing of LEDs and the like, and auditory notification means such as a buzzer generator. Moreover, the alerting | reporting part 16 may provide a liquid crystal screen etc. and may perform alerting | reporting operation | movement by a character display, a symbol display, etc.

  As shown in FIG. 2, the reference microphone 11 is located on the fan 2 side on the inner surface of the hood 1, and the error microphone 12 is located on the intake port 1 a side on the inner surface of the hood 1. The speaker 13 is located between the reference microphone 11 and the error microphone 12 on the inner surface of the hood 1. That is, the error microphone 12, the speaker 13, and the reference microphone 11 are arranged in this order in the air passage from the air inlet 1 a to the fan 2.

  As shown in FIG. 1, in the control block A1, the mute control block 14 includes a cancel sound generation unit 14a and a control unit 14b. Then, the mute control block 14 outputs a cancel sound that cancels the operation sound of the fan 2 as a noise source from the speaker 13 so that the sound pressure level at the installation point of the error microphone 12 is minimized. Suppresses noise transmitted to the room sometimes. That is, the silencing control block 14 performs active noise control, and executes a silencing program that realizes the function of an adaptive filter in order to follow the noise change of the fan 2 and the noise propagation characteristic. For example, a Filtered-X LMS sequential update control algorithm is used to update the filter coefficient of the adaptive filter.

  Specifically, the reference microphone 11 collects the operation sound of the fan 2 and outputs a reference signal. This reference signal is input to the mute control block 14 after being subjected to amplification processing and A / D conversion processing.

  The error microphone 12 collects a synthesized sound of the operation sound of the fan 2 and the cancel sound and outputs an error signal. This error signal is input to the mute control block 14 after being subjected to amplification processing and A / D conversion processing.

  In the mute control block 14, the cancel sound generation unit 14 a is configured by an adaptive filter that generates a cancel sound that cancels noise based on the reference signal from the reference microphone 11. This canceling sound is formed in a waveform having an opposite phase and the same amplitude as the waveform of the operating sound of the fan 2.

  The error signal from the error microphone 12 is input to the control unit 14b. The control unit 14b updates the filter coefficient of the cancellation sound generation unit 14a as necessary so that the error signal is minimized, thereby operating the cancellation sound generation unit 14a so that the noise reduction effect by the cancellation sound is maximized. Control.

  The cancellation sound generated by the cancellation sound generation unit 14a is output from the speaker 13 after being subjected to D / A conversion processing and amplification processing. That is, as shown in FIG. 5, the canceling sound waveform Y1 has the same phase and amplitude as the operating sound waveform Y2 of the fan 2, and propagates from the fan 2 through the hood 1 to the intake port 1a. Noise transmitted to the room is reduced.

  Next, the operation of the dirt detection block 15 which is the gist of the present invention will be described.

  As shown in FIG. 1, the dirt detection block 15 includes a determination unit 15a, a storage unit 15b, and a determination table 15c. The operation will be described with reference to the flowchart of FIG.

  First, the fan 2 starts operation by a trigger such as a switch operation (for example, pressing of a ventilation operation button) (not shown) by the user (S1). At this time, the reference microphone 11 and the error microphone 12 collect the operation sound of the fan 2 and output a reference signal and an error signal. Then, the determination unit 15a collects the reference signal and the error signal output from the reference microphone 11 and the error microphone 12 until a predetermined time elapses after the fan 2 starts operating, and stores it in the storage unit 15b (S2). ). Then, the determination unit 15a performs frequency analysis of the reference signal and the error signal stored in the storage unit 15b (S3). The mute control block 14 starts active noise control after the process of step S2 by the determination unit 15a is completed.

Next, the determination unit 15a refers to the determination table 15c stored in a memory such as a ROM, and each of the reference microphone 11, the error microphone 12, and the speaker 13 based on the frequency analysis result of the reference signal and the error signal. The degree of dirt adhesion is determined (S4).

The determination table 15c shown in FIGS. 7A and 7B is a graph showing the relationship between the sensitivity reduction level of the microphone and the amount of dirt attached to the microphone for each of a plurality of frequency bands. FIG. 7A is graph data showing a relationship between the amount of dirt adhered to the microphone and the sensitivity reduction level of the microphone in a signal component of 500 Hz. FIG. 7B is graph data showing the relationship between the amount of dirt adhered to the microphone and the sensitivity reduction level of the microphone in the signal component of 1000 Hz. The graph data is common to the reference microphone 11 and the error microphone 12, but the graph data of the reference microphone 11 and the error microphone 12 may be created individually. Moreover, the frequency band to graph is not limited, For example, you may graph by 1/3 octave space | interval.

  In the determination unit 15a, the reference power level (dB) of the reference signal and the error signal (that is, the power level of each signal in a state where the sensitivity of the microphone is not reduced) is set in advance for each frequency band. The determination unit 15a derives the sensitivity reduction level of each microphone for each frequency band by subtracting the power level based on the frequency analysis result of the reference signal and the error signal from the reference power level of the reference signal and the error signal.

  The determination unit 15a obtains the amount of dirt attached to each microphone based on the respective sensitivity reduction levels of the reference microphone 11 and the error microphone 12, and if the amount of dirt attached is equal to or greater than a predetermined threshold value, the notification unit 16 notifies the notification unit 16 of a notification signal. Is output. For example, the determination unit 15a outputs a first notification signal to the notification unit 16 if the amount of dirt attached to the reference microphone 11 is equal to or greater than a predetermined threshold, and the amount of dirt attached to the error microphone 12 is equal to or greater than the predetermined threshold. Then, the second notification signal is output to the notification unit 16. Note that the determination unit 15a may output a notification signal when the amount of adhered dirt on the microphone is equal to or greater than a predetermined threshold in any one frequency band. Alternatively, the determination unit 15a may output a notification signal when the amount of dirt adhered to the microphone is equal to or greater than a predetermined threshold in a plurality of frequency bands.

Further, when dirt is attached to the speaker 13 , the frequency characteristics of the canceling sound output from the speaker 13 change. Therefore, when dirt is attached to the speaker 13, the frequency characteristics of the reference signal and error signal collected by the reference microphone 11 and the error microphone 12 also change. Therefore, the determination table 15 c, reference signal in the case where stains are adhered to the speaker 13 may be stored also the frequency characteristic data of the error signal, the determination unit 15a in step S4, also adhering of dirt speaker 13 judge. And the determination part 15a outputs a 3rd alerting | reporting signal to the alerting | reporting part 16, when the adhesion amount of the dirt of the speaker 13 becomes more than a predetermined threshold value.

  When receiving the first notification signal from the determination unit 15a, the notification unit 16 performs a notification operation that prompts the user to clean the reference microphone 11 such as wiping or cleaning. In addition, when receiving the second notification signal from the determination unit 15a, the notification unit 16 performs a notification operation that prompts the user to clean the error microphone 12 such as wiping or cleaning. Further, when receiving the third notification signal from the determination unit 15a, the notification unit 16 performs a notification operation that prompts the user to clean the speaker 13 such as wiping (S5).

  Then, when the user recognizes the cleaning timing of the reference microphone 11, the error microphone 12, and the speaker 13 by the notification operation by the notification unit 16, the user cleans the reference microphone 11, the error microphone 12, and the speaker 13.

  Each of the cleaned reference microphone 11, error microphone 12, and speaker 13 can recover original performance (microphone sensitivity and frequency characteristics, speaker output frequency characteristics, etc.). Therefore, the noise reduction effect by the silencing control block 14 is also restored. In other words, the silencer A can appropriately notify the user of the cleaning timing and maintain the noise reduction effect by the active noise control.

  Furthermore, since the dirt detection block 15 determines the degree of dirt on the reference microphone 11, the error microphone 12, and the speaker 13 based on the actual operation sound of the fan 2, it is necessary to provide a means for generating evaluation sound described later. The configuration can be simplified.

In addition, as shown in FIG. 8, for example, the determination table 15 c graphs the relationship between the power level (dB) and the frequency (Hz) of the reference signal and the error signal according to the degree of dirt attached to the microphone. You may have done. FIG. 8 shows a characteristic Y11 when the amount of dirt attached is small, a characteristic Y12 when the amount of dirt attached is medium, and a characteristic Y13 when the amount of dirt attached is large. In the characteristics Y11 to Y13, the power level in the high frequency band decreases as the amount of dirt attached increases.

Then, the determination unit 15a refers to the determination table 15 c in FIG. 8, based on the frequency characteristics of the power level of the reference signal and the error signal, the reference microphone 11 obtains the fouling of error microphone 12. Then, the determination unit 15a outputs a first notification signal to the notification unit 16 if the amount of dirt attached to the reference microphone 11 is equal to or greater than a predetermined threshold, and the amount of dirt attached to the error microphone 12 is equal to or greater than the predetermined threshold. Then, the second notification signal is output to the notification unit 16.

Further, the determination table 15c is not limited to a graph, and may be other forms of data such as a number table.

  The reference microphone 11, the error microphone 12, and the speaker 13 can be cleaned (care) by, for example, “wiping with a cleaning agent and cloth”, “removing and cleaning the silencer A from the hood 1”, and “silencer”. For example, “exchange A”.

  Furthermore, the hood 1 may be composed of a plurality of air passages, and the muffler unit U may be disposed in each air passage.

(Embodiment 2)
The block configuration of the silencer A of the present embodiment is shown in FIG. 9, the same reference numerals are given to the same configurations as those of the first embodiment, and the description will be omitted.

  In the muffler A of the present embodiment, the dirt detection block 15 is provided with an evaluation sound reproducing unit 15d, and the operation of the dirt detection block 15 will be described with reference to the flowchart of FIG.

  When the fan 2 is not operating, the evaluation sound reproducing unit 15d outputs an evaluation sound from the speaker 13 by a trigger such as a switch operation (not shown) by the user (for example, pressing a maintenance check button) (S11). . This evaluation sound is a pseudo sound of the operation sound of the fan 2, is created in advance based on the operation sound of the fan 2, and is stored in a memory such as a ROM provided in the evaluation sound reproduction unit 15d. At this time, the reference microphone 11 and the error microphone 12 collect the evaluation sound and output a reference signal and an error signal.

  Then, the determination unit 15a collects the reference signal and the error signal output from the reference microphone 11 and the error microphone 12 until a predetermined time has elapsed from the start of the output of the evaluation sound, and stores it in the storage unit 15b (S12). Then, the determination unit 15a performs frequency analysis of the reference signal and the error signal stored in the storage unit 15b (S13).

Next, the determination unit 15a refers to the determination table 15c stored in a memory such as a ROM, and each of the reference microphone 11, the error microphone 12, and the speaker 13 based on the frequency analysis result of the reference signal and the error signal. The degree of dirt adhesion is determined (S14). The determination unit 15a obtains the amounts of dirt adhering to the reference microphone 11, the error microphone 12, and the speaker 13 based on the sensitivity reduction levels of the reference microphone 11 and the error microphone 12, and the frequency characteristics of the reference signal and the error signal. Then, the determination unit 15a outputs a first notification signal to the notification unit 16 if the amount of dirt attached to the reference microphone 11 is equal to or greater than a predetermined threshold, and the amount of dirt attached to the error microphone 12 is equal to or greater than the predetermined threshold. Then, the second notification signal is output to the notification unit 16. Further, the determination unit 15 a outputs a third notification signal to the notification unit 16 when the amount of dirt attached to the speaker 13 exceeds a predetermined threshold.

  When receiving the first notification signal from the determination unit 15a, the notification unit 16 performs a notification operation that prompts the user to clean the reference microphone 11 such as wiping or cleaning. In addition, when receiving the second notification signal from the determination unit 15a, the notification unit 16 performs a notification operation that prompts the user to clean the error microphone 12 such as wiping or cleaning. Further, when receiving the third notification signal from the determination unit 15a, the notification unit 16 performs a notification operation that prompts the user to clean the speaker 13 such as wiping (S15).

  Then, when the user recognizes the cleaning timing of the reference microphone 11, the error microphone 12, and the speaker 13 by the notification operation by the notification unit 16, the user cleans the reference microphone 11, the error microphone 12, and the speaker 13.

  Each of the cleaned reference microphone 11, error microphone 12, and speaker 13 can recover original performance (microphone sensitivity and frequency characteristics, speaker output frequency characteristics, etc.). Therefore, the noise reduction effect by the silencing control block 14 is also restored. In other words, the silencer A can appropriately notify the user of the cleaning timing and maintain the noise reduction effect by the active noise control.

  Furthermore, since the characteristics (volume, frequency characteristics, etc.) of the evaluation sound are determined in advance, the dirt detection block 15 can accurately determine the degree of dirt attached to the reference microphone 11, the error microphone 12, and the speaker 13. .

  In addition, when the determination unit 15a determines the degree of dirt adhesion of each part using the actual operation sound of the fan 2, it takes time until the fan 2 operates normally and the frequency spectrum of the operation sound is stabilized. The determination process also takes time. On the other hand, in the present embodiment, since a known evaluation sound stored in advance in the evaluation sound reproduction unit 15d is used, only the determination process by the determination unit 15a can be performed in a short time. Further, by using a pseudo sound of the operation sound of the fan 2 as the evaluation sound, unnatural feeling and uncomfortable feeling during operation of the dirt detection block 15 are reduced.

  The evaluation sound may be a white noise whose frequency characteristics are flat and the sensitivity reduction level is easy to analyze, or a sound source whose frequency characteristics in the hood 1 are flat in consideration of the resonance characteristics of the hood 1.

  Further, after the dirt detection block 15 completes the operation of the flowchart shown in FIG. 10, driving of the fan 2 and active noise control by the mute control block 14 are started. The start of driving the fan 2 and the start trigger of active noise control by the silence control block 14 may be either automatic or manual.

(Embodiment 3)
The configuration of the silencer A of the present embodiment is the same as that of the second embodiment, and the same components are denoted by the same reference numerals and description thereof is omitted.

  The silencer A of the present embodiment is characterized in that the determination unit 15a determines a cleaning location in the hood 1 in accordance with the degree of contamination of the reference microphone 11 and the error microphone 12, and the flowchart of FIG. It explains using.

  First, the evaluation sound reproducing unit 15d outputs an evaluation sound from the speaker 13 by a trigger such as a switch operation (for example, pressing of a maintenance check button) (not shown) by the user when the fan 2 is stopped. S21). This evaluation sound is a pseudo sound of the operation sound of the fan 2, is created in advance based on the actual operation sound of the fan 2, and is stored in the evaluation sound reproducing unit 15d. At this time, the reference microphone 11 and the error microphone 12 collect the evaluation sound and output a reference signal and an error signal.

  Then, the determination unit 15a collects the reference signal and the error signal output from the reference microphone 11 and the error microphone 12 until a predetermined time has elapsed from the start of the output of the evaluation sound, and stores it in the storage unit 15b (S22). Then, the determination unit 15a performs frequency analysis of the reference signal and the error signal stored in the storage unit 15b (S23).

Next, the determination unit 15a refers to the determination table 15c stored in a memory such as a ROM, and attaches each stain of the reference microphone 11 and the error microphone 12 based on the frequency analysis result of the reference signal and the error signal. Determine the condition.

  First, the determination unit 15 a obtains each dirt adhesion amount of the reference microphone 11 and the error microphone 12 based on the sensitivity reduction levels of the reference microphone 11 and the error microphone 12. Then, the determination unit 15a distributes the dirt adhesion amounts of the reference microphone 11 and the error microphone 12 to any one of the three ranks [0], [1], and [2] in ascending order.

  The rank [0] has a dirt adhering amount less than the threshold value X1, and corresponds to an initial state such as a new state or a state after cleaning, for example. The rank [0] can be set for both the reference microphone 11 and the error microphone 12.

  The rank [1] is an intermediate amount of dirt adhering with a dirt adhering amount equal to or greater than the threshold value X1 and less than the threshold value X2 (where X1 <X2). Rank [1] can be set only for the reference microphone 11.

  The rank [2] is a state in which the dirt adhesion amount is greater than or equal to the threshold value X2, the dirt adhesion quantity is large, and the dirt adhesion quantity starts to affect the active noise control. The rank [2] can be set for both the reference microphone 11 and the error microphone 12.

  Then, the determination unit 15a outputs a notification signal indicating the cleaning location according to the combination of the ranks of the dirt adhesion amounts of the reference microphone 11 and the error microphone 12. Hereinafter, when the rank of the reference microphone 11 is Ra and the rank of the error microphone 12 is Rb, a combination of the ranks of the dirt adhesion amounts of the reference microphone 11 and the error microphone 12 is indicated by [Ra, Rb]. Further, the combination [Ra, Rb] of the dirt adhesion amount ranks of the reference microphone 11 and the error microphone 12 is referred to as a dirt adhesion amount rank [Ra, Rb].

  First, the determination unit 15a determines whether or not the dirt adhesion amount rank is [1, 0] (S24). And the determination part 15a outputs the 4th alerting signal which shows a cleaning location, when a dirt adhesion amount rank is [1, 0]. The fourth notification signal is a notification signal that prompts cleaning of the filter 3 and the rectifying plate 4 provided in the intake port 1 a of the hood 1. When the notification unit 16 receives the fourth notification signal from the determination unit 15a, the notification unit 16 performs a notification operation that prompts cleaning of the filter 3 and the rectifying plate 4 provided in the intake port 1a of the hood 1 (S25).

  If the dirt adhesion amount rank is not [1, 0], the determination unit 15a determines whether the dirt adhesion amount rank is [2, 0] (S26). And the determination part 15a outputs the 5th alerting signal which shows a cleaning location, when a dirt adhesion amount rank is [2, 0]. The fifth notification signal is a notification signal that prompts the user to clean the reference microphone 11 and the periphery of the reference microphone 11 without removing the muffling unit U from the hood 1. When the notification unit 16 receives the fifth notification signal from the determination unit 15a, the notification unit 16 performs a notification operation that prompts cleaning to wipe only the reference microphone 11 and the periphery of the reference microphone 11 without removing the muffling unit U from the hood 1 ( S27).

  Further, when the dirt adhesion amount rank is not [2, 0], the determination unit 15a determines whether or not the dirt adhesion amount rank is [*, 2] (S28). Note that * may be 0, 1, or 2. And the determination part 15a outputs the 6th alerting signal which shows a cleaning location, when a dirt adhesion amount rank is [*, 2]. The sixth notification signal removes the silencing unit U and the fan 2 from the hood 1 and prompts the silencing unit U (particularly, the reference microphone 11, the error microphone 12, the speaker 13, and their surroundings) and the fan 2 to be cleaned. This is a notification signal. When the notification unit 16 receives the sixth notification signal from the determination unit 15a, the notification unit 16 performs a notification operation that prompts cleaning of the mute unit U and the fan 2 (S29).

  FIG. 12 shows a state transition diagram when the determination unit 15a performs the cleaning portion determination process described above. It is assumed that dirt in the hood 1 gradually adheres from the intake port 1a side to the fan 2 side.

  For example, when the dirt adhesion amount rank is the initial state [0, 0], the state Q1 is set. In the state Q1, the notification operation by the notification unit 16 is not performed.

  When the dirt adhesion amount of the reference microphone 11 increases with the passage of time and the dirt adhesion amount rank becomes [1, 0], the state Q1 is changed to the state Q2. In the state Q2, a notification operation for urging cleaning of the filter 3 and the rectifying plate 4 provided in the intake port 1a of the hood 1 is performed.

  When the dirt adhesion amount of the reference microphone 11 further increases and the dirt adhesion amount rank becomes [2, 0], the state Q2 is changed to the state Q3. In the state Q3, without removing the muffling unit U from the hood 1, a notification operation for urging cleaning to wipe only the reference microphone 11 and the periphery of the reference microphone 11 is performed. Then, by cleaning only the reference microphone 11 and the periphery of the reference microphone 11, the state returns from the state Q3 to the initial state Q1.

  In the state Q2, when the amount of dirt attached to the error microphone 12 is increased and the dirt attached amount rank is [1, 2], the state Q2 is changed to the state Q4. Alternatively, in the initial state Q1, when the dirt adhesion amounts of the reference microphone 11 and the error microphone 12 are increased and the dirt adhesion amount rank is [1, 2], the state transitions from the initial state Q1 to the state Q4. In the state Q4, a notification operation that prompts cleaning of the muffler unit U removed from the hood 1 and the fan 2 is performed. Then, the mute unit U and the fan 2 are cleaned to return from the state Q4 to the initial state Q1. Note that transitions between the states Q1, Q2 and the state Q4 (broken arrows in FIG. 12) are unlikely to occur.

  In the initial state Q1, when the amount of dirt attached to the error microphone 12 increases and the dirt attached amount rank becomes [0, 2], the state Q1 is changed to the state Q5. In the state Q5, a notification operation for urging the cleaning of the silencer unit U removed from the hood 1 and the fan 2 is performed. Then, the cleaning unit U and the fan 2 are cleaned to return from the state Q5 to the initial state Q1.

  Thus, in the present embodiment, the cleaning location is presented based on the amount of dirt attached to the reference microphone 11 and the error microphone 12, so that it is possible to notify the maintenance method more appropriately.

  Further, by cleaning the fan 2, the basic performance (intake amount, exhaust amount, etc.) of the fan 2 can be maintained, and the function as a range hood device can also be maintained.

  In each embodiment, the determination unit 15 a determines the degree of contamination of each unit based on both outputs of the reference microphone 11 and the error microphone 12. However, the determination unit 15a may determine the degree of contamination of each unit based on the output of one of the reference microphone 11 and the error microphone 12.

  Moreover, in each embodiment, the determination part 15a should just be the structure which determines at least one of each dirt condition of the reference microphone 11 and the error microphone 12, and the dirt condition of the speaker 13. FIG.

  Moreover, you may use the silencer A for the objective of reducing the noise generate | occur | produced not only in a range hood but in the space containing ventilation paths, such as an air conditioning duct, an electric equipment, and a tunnel.

A Silencer 11 Reference microphone (first microphone)
12 Error microphone (second microphone)
13 Speaker 14 Silence Control Block 14a Cancel Sound Generation Unit 14b Control Unit 15 Dirt Detection Block 15a Judgment Unit 16 Notification Unit

Claims (7)

A first microphone provided in a space where sound emitted from a noise source propagates;
A cancellation sound generating unit that generates a cancellation sound that cancels the sound emitted from the noise source based on the sound collected by the first microphone;
A speaker that outputs the cancellation sound to the space;
A second microphone for collecting a synthesized sound of the sound emitted from the noise source and the cancellation sound in the space;
A control unit that controls generation processing of the cancellation sound by the cancellation sound generation unit so that the sound collected by the second microphone is reduced;
The relationship between the degree of contamination of the first microphone and the second microphone and the frequency characteristics of the outputs of the first microphone and the second microphone, the degree of contamination of the speaker, the first microphone, and the A determination table indicating at least one of the relationships with the frequency characteristics of the outputs of the second microphone;
Based on the first microphone and the second of the determination table and each output of the microphone, determining at least one of the cleanliness of the first microphone and the second the cleanliness and the speaker microphone A determination unit to perform,
A muffler comprising: a notification unit that performs a notification operation based on a determination result of the determination unit. The determination table includes a relationship between each dirt condition of the first microphone and the second microphone and a frequency characteristic of each output of the first microphone and the second microphone, a dirt condition of the speaker, and the first microphone. Showing the relationship between the frequency characteristics of each output of the first microphone and the second microphone;
The determination unit, based on the first microphone and the second of the determination table and each output of the microphones, the first microphone, the second microphone, determines the contamination degree of the speaker The muffler according to claim 1.   3. The silencer according to claim 1, wherein the determination unit determines a cleaning location in the space in accordance with the degree of contamination of the first microphone and the second microphone.   The silencer according to any one of claims 1 to 3, wherein the noise source is a fan that sucks air from one side of the ventilation path forming the space to the other side. The determination unit is configured to at least the first microphone based on a result of each of the first microphone and the second microphone collecting the operation sound of the fan within a predetermined time after the fan starts operating. The silencer according to claim 4, wherein the degree of contamination of each of the first microphone and the second microphone is determined. An evaluation sound reproducing unit for outputting an evaluation sound from the speaker;
The determination unit determines at least each dirt level of the first microphone and the second microphone based on a result of collecting the evaluation sound output from the speaker when the fan is stopped. The silencer according to claim 4, wherein   The silencer according to claim 6, wherein the evaluation sound is a pseudo sound of the operation sound of the fan.

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