JPH06102885A - Active silencer in three dimensional space - Google Patents

Abstract

PURPOSE:To provide an active silencer which enable selecting an arbitrary position within three dimensional space for a local silent region desired to be silent and also enable selecting arbitrarily the number and size of silent regions. CONSTITUTION:Detected sounds from detecting means 1a, 1b for noise generated by a noise source (air conditioner 5) and silent effect detecting means 3a, 3b are analyzed by a controller 4 for active silence, sound for active silence being an opposite phase to noise and having the same sound pressure and wavelength as noise at a setting position of the silent effect detecting means is issued, then active silence is performed within a local silence region around the silent effect detecting means. The silent effect detecting means, a position and the number of a sounding means are made variable by making signal transmission lines 7a and 7c between each apparatus flexible and movable wire or wireless.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active muffling device that actively muffles noise in a local area of a three-dimensional space.

[0002]

BACKGROUND OF THE INVENTION The basic idea of so-called active muffling, in which noise is muffled with sound from another sound source, is known from the US patent of 1936. However, it was necessary to simultaneously add sounds having the same wavelength (same frequency) and the same amplitude as the noise, which was not realized when the technical method was immature.

However, due to recent advances in digital signal processing technology, sound waves of the same amplitude and the same wavelength can be produced at the same time as noise, and active muffling can be realized. Has been put to practical use when it propagates. This will be described with reference to FIG.

As shown in FIG. 3 (a), noise from upstream (left side in the figure) in the duct is measured by the noise detecting means 1 and sent to the controller 4 as an electric signal. This is analyzed by the controller 4, and an output signal is sent to the sounding means for active muffling so that a sound of opposite phase is emitted from the sounding means 2 into the duct, and the muffling effect is measured by the muffling effect detecting means 3,
Based on this, the controller 4 corrects the output signal to the sounding means 2 by feedback control so that the sound is always muted at the position of the sound deadening effect detecting means 3. In this way, the sound is silenced at the position of the sound deadening effect detection means 3 and at the downstream side (right side in the drawing). Here the controller 4 includes a fixed filter H _o, in performing digital signal processing, as shown in FIG. 3 (b), as the fixed filter H _o, from silencing effect detecting means 3 to the controller 4 measured values of transfer functions defined by the quotient of the voltage V ₂ of the input signal from the voltage V ₃ and the controller 4 of the output signal to the sound generating means 2 is on. Actually, at the time of actual measurement, an M-series sound wave signal is output from the controller 4 as white noise, radiated from the sounding means 2, and the sound wave signal returned by the muffling effect detection means 3 at that time is H.
_o is required. As a result, the distance between the sound producing means 2 and the sound deadening effect detecting means 3 and the reverberation characteristic in the duct, and the device characteristics of the sound producing means 2 and the sound deadening effect detecting means 3 are taken in,
Each characteristic can be corrected when the sound is muted.

[0005]

The present invention relates to active noise reduction in a three-dimensional space such as a room. Active noise reduction in a three-dimensional space is different from active noise reduction of a one-dimensional sound wave in a duct. As shown in FIG. 4, the same amplitude and the same frequency emitted from two point sound sources in the three-dimensional space,
In the interference of sound waves of opposite phases, sound deadening areas that cancel each other and sound boosting areas that mutually strengthen each other occur in places. Therefore, when one of the two sound sources is a noise source, the other sound source is used as a sounding means for active sound deadening, whereby active sound deadening is possible in a local region in the three-dimensional space. Since the size of this local region where active noise reduction is possible and the noise reduction effect are proportional to the wavelength of the sound, depending on the position and size of the local region where noise reduction or noise reduction is desired, the frequency of the sound, and the purpose of noise reduction, It is necessary to provide a plurality of or singular sound deadening effect detecting means, a plurality of singular sound generating means, and a plurality of singular noise detecting means, and to devise different installation positions and ways of operating these devices. Furthermore, it is necessary to consider the space in the room to be silenced, the aesthetics of the interior, and the cost of each device. The present invention aims to solve these problems in active noise reduction in a three-dimensional space.

[0006]

SUMMARY OF THE INVENTION The present invention provides a three-dimensional active muffling device as claimed in the appended claims.

[0007]

In the active muffling apparatus of the present invention, the position, the number, and the size of the muffling area are determined according to the installation position and the number of the muffling effect detecting means, and further according to the installation position and the number of the sound producing means.
The muffling effect can be changed. Further, the flexibility can be further enhanced by radiating the sound from the sound producing means from a desired position by the sound guide tube.

[0008]

FIG. 1 shows an embodiment of the present invention. Noise generated by the air outlet and the air inlet of the air conditioner 5 is detected by the noise detecting means 1a, 1
The noise is detected by b, analyzed by the controller 4, and the sound of the opposite phase for active muffling is emitted from the sounding means 2a, 2b, so that the sound is muted at the position of the muffling effect detecting means 3a, 3b. Here, the wiring 7a, 7 connecting between these devices
By using a parallel cord, a coaxial cable, or an optical fiber as b and 7c, the installation position of each device can be freely selected and a large amount of information can be transmitted. In the example shown in FIG. 1, two local regions near the human ear are selected as two silencing regions to be muted, and the silencing effect detecting means 3a, 3a
By placing 3b, a sound deadening area is created at each person's ear, and noise reduction is realized in these sound deadening areas.

FIG. 2 is a control system connection diagram for performing the active noise reduction shown in FIG. The noise detecting means 1a and 1b are provided at the air outlet and the air inlet of the air conditioner 5, respectively, and can detect most of the noise from the air conditioner 5, and the detection signal is passed through the mixer and the filter H. It is transmitted to the controller 4 as an appropriate electric signal representing the noise of the air conditioner. The controller 4 analyzes and calculates the above-mentioned electrical signal and the electrical signal of the sound in each muffling area detected by the muffling effect detecting means 3a, 3b installed in the two muffling areas near the ears to calculate the muffling effect. Detection means 3
An electric signal that causes the two sounding means 2a, 2b to make a sound that reduces the sound detected by a, 3b is sent to the sounding means 2a, 2b via the power amplifier. The air conditioner 5
By connecting the remote control 6 for use directly to the controller 4, the mute control is turned on and off, or the BGM is performed.
Sounds such as (background music) are also emitted from the sounding means 2a and 2b at the same time, and the sound of the BGM is o.
n, off and selection are possible at hand. In this embodiment, condenser microphones are used as the noise detection means 1 and the noise reduction effect detection means 3 in order to reduce cost and influence of magnetism.

FIG. 5 shows another embodiment of the present invention. The fan rotation speed, which is the noise from the air conditioner 5, and the fan rotation speed and the waveform of the power source, which are the basis of electromagnetic noise, are detected by the pickups 1a and 1b as noise detection means, while the noise reduction effect detection means 3a and 3b are used. , Sound in the sound deadening regions selected at two places around the human ear is detected by the sound deadening effect detecting means 3a and 3b, respectively. These detected sound signals are sent to the controller 4
The controller 4 performs an analytical calculation based on these signals to give the sound for active muffling from the sounding means 2a, 2b to the muffling area so as to reduce the sound in the two muffling areas. Sounding means 2a, 2b
Send to. As a result, the sound is muted in the two muting areas. Here, by using radio waves or infrared rays as a signal transmitting means for connecting the respective devices, it is possible to freely select the installation position of each device and to transmit a large amount of information without troublesome wiring work.

In the example shown in FIG. 5, in order to muffle sound at two places near the ear of a person, muffling effect detection means 3a, 3b installed at positions separated from the ears as shown are used. By setting the actual measurement value of the transfer function between 3b and the ear in the controller 4 in advance, the sound deadening effect in the sound dead area of the ear is detected. Also, sounding means 2
Sounds from a and 2b are transmitted to an optimum position with respect to the sound deadening region near the ears by using hollow tubes 8a and 8b, etc., so that the sound generating means 2a and 2b can be installed at appropriate separated positions.

FIG. 6 is a diagram showing the connection of the control system for performing the active muffling shown in FIG. Noise detection means 1a,
The signal detected by 1b also passes through a signal processing circuit to generate n (usually 1 to 4) times the component of the wavelength indicated by the signal, and further represents the noise of the air conditioner by passing through a mixer and a filter. It is transmitted to the controller 4 as an appropriate electric signal. The controller 4 performs analysis / calculation based on the electric signal and the signals from the muffling effect detecting means 3a and 3b.
An electric signal to be sent to the sound producing means 2a, 2b in order to generate a sound for active muffling that reduces the output signal from a, 3b is generated, and then this electric signal is applied to the ears and the sound deadening effect detecting means 3a, 3b. By passing through a filter having measured values H ₁ and H ₂ of the transfer function between and, it is corrected as an electric signal of a sound that can be muted at the ears and sent to the sounding means 2a and 2b. Since the sound producing means 2a, 2b have a built-in power amplifier, a compact and sufficient sound can be output from the sound producing means 2a, 2b. In addition,
Since the sound generators 2a and 2b can output a BGM, a message, or a sound that feels cool during mental comfort or cooling and warm during heating, the output of the transmitter 11 and a controller that emit such a sound signal are output. It is possible to combine the signal from No. 4 via the mixers 12a and 12b. Further, similar to the example shown in FIG. 2, the remote controller 6 is used to easily control on / off of the control.

FIG. 7 shows another sounding means (for example, a speaker for stereo music) 2a, which is already provided in the room 9.
If there is already a system 2b and a system (device for stereo music, etc.) 10 for driving the system 2b, the sound producing means 2a, 2
This is an example in which the noise from the air conditioner 5 provided in the room 9 is actively silenced within the local region indicated by the dotted line by connecting the active silencing control system as described above to the system b and the system 10.
In the active muffling device according to the present invention, since the sounding means for active muffling can be installed outside the air conditioner 5, as in this embodiment, another sounding means 2 already provided in the room 9 is provided.
Since a and 2b can be used as the sound producing means for active muffling, the cost can be reduced. In this case, the muffling effect detecting means 3a, 3b are installed in a local region to be muffled, but are placed in a filter provided in the controller, and the transfer function between the muffling effect detecting means 3a, 3b and the sound producing means 2a, 2b is inserted. Muffling effect detection means 3 only by changing the measured value
The a and 3b can be installed at any position in the room 9, and the sound deadening area can be selected at any position.

FIG. 8 shows an embodiment in which a plurality of sound deadening areas, a plurality of sound deadening effect detecting means 3 and a controller 4 capable of multi-channel active sound deadening control are used to create a plurality of sound deadening areas in a room 9. is there. According to this embodiment, low noise can be realized for many people in the room 9. Each muting area is actively muted by the corresponding closest sounding means. Here, the controller 4 is provided outside or inside the air conditioner 5 and can be replaced, and the number of channels that can be muted can be freely selected. Also in this example, each muffling area indicated by a dotted line moves a plurality of sounding means 2 and a plurality of muffling effect detecting means 3, respectively, as in the example shown in FIG. By changing it and putting it in the filter in the controller 4, it can be made at an arbitrary position. Further, a plurality of noise detecting means 1 are also used so that the noise from the air conditioner can be detected accurately and accurately.

FIG. 9 shows an embodiment in which the active muffling control system similar to that shown in FIG. 8 is used to create one large muffling area as indicated by a broken line A as a set in which a plurality of muffling areas overlap. In the embodiment shown in FIG. 9, a plurality of muffling effect detecting means 3 are concentrated and installed at constant intervals, so that the muffling area is enlarged as indicated by A. FIG. 10 shows how to install the plurality of muffling effect detecting means 3 in this case. Since the size of the sound deadening region is proportional to the wavelength of the sound to be muted, the distance δ between the plurality of sound deadening effect detecting means 3 is expressed by the following formula (1) (where Means that δ is within 1/2 of the wavelength of the sound to be erased), or equation (2) (this means that δ is within 1/3 of the wavelength of the sound to be erased).

[0016]

[Equation 1]

[0017]

[Equation 2]

A plurality of muffling effect detecting means 3 are installed in the muffling area A so as to satisfy the above condition. Furthermore, when it is desired to mute only χ (db) at the noise level, the muffling effect detection means 3
The distance δ between them is a value calculated by the equation (3).

[0019]

[Equation 3]

Here, f is the wavelength of the sound to be erased, y is an index indicating the control accuracy of the algorithm in the controller 4, and 0 <y
<1 (If the control accuracy is good, it approaches 1). Sounding means 2
There is no special restriction on the position of
It is desirable to install them in or near them, and as close to the respective silencing effect detection means 3 as possible. This is because noise is generally increased in a place other than the sound deadening region due to the interference of the sounds, so that it is reduced.

In FIG. 11, when there is another noise source S in addition to the air conditioner 5, another noise detecting means 1c for the noise source S is provided and connected to the controller 4, so that noise other than the air conditioner is also air-conditioned. An embodiment will be shown in which the noise of the machine is turned off at the same time. As a result, a large amount of noise can be silenced by one active silencer, and the active silencer of an air conditioner can be effectively used with added value.

INDUSTRIAL APPLICABILITY The present invention is applicable to various types of air-conditioning indoor units, or, without being limited thereto, generally active muffling of noise generated by a noise source.

[0023]

According to the present invention, it is possible to freely set the position, the number or the size of the local area to be silenced. Also,
The sound deadening effect detecting means and the sound producing means can be selected in an appropriate place in consideration of space availability and aesthetics in the room.

[Brief description of drawings]

FIG. 1 is a diagram of an embodiment in which active noise reduction according to the present invention is applied to an air conditioner.

FIG. 2 is a diagram showing a connection configuration of an active muffling control system of the embodiment shown in FIG.

FIG. 3 is a configuration diagram (a) and a diagram of a fixed filter (b) showing a conventional technique for performing active noise reduction control of one-dimensional sound waves in a duct.

FIG. 4 is a diagram showing how three-dimensional sound waves from two point sources having opposite phases interfere with each other.

FIG. 5 is a diagram of another embodiment in which active noise reduction according to the present invention is applied to an air conditioner.

FIG. 6 is a diagram showing a connection configuration of an active muffling control system of the embodiment shown in FIG.

FIG. 7 is a diagram showing still another embodiment in which the active noise reduction according to the present invention is applied to an air conditioner.

FIG. 8 is a diagram showing another embodiment in which active muffling according to the present invention is applied to an air conditioner.

FIG. 9 is a diagram showing still another embodiment in which the active noise reduction according to the present invention is applied to an air conditioner.

FIG. 10 is a diagram for explaining the distance between a plurality of muffling effect detecting means in the embodiment shown in FIG.

FIG. 11 is a diagram showing still another embodiment using active muffling according to the present invention.

[Explanation of symbols]

1, 1a, 1b ... Noise detecting means 2, 2a,
2b ... Sound generating means 3, 3a, 3b ... Silencer effect detecting means 4 ... Controller 5 ... Air conditioner 6 ... Remote controller 7, 7a, 7b, 7c ... Transmitting means 8a, 8b, 7c ... Sound wave transmitting tube 9 ... Performing active silencing Room 11 ... Transmission means 12 ... Mixer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Izushi, 390 Muramatsu, Shimizu City, Shizuoka Prefecture, Hitachi, Ltd. Shimizu Plant (72) Inventor, Hiroshi Takenaka, 390, Muramatsu, Shimizu City, Shizuoka, Ltd. 72) Inventor Masahiro Ito 390 Muramatsu, Shimizu City, Shizuoka Prefecture Inside the Shimizu Plant, Hitachi, Ltd.

Claims (7)

[Claims] 1. A noise detecting means for detecting a noise emitted from a noise source, a sound producing means for emitting a sound for active muffling, and a muffling effect detecting means installed in a local muffling area and detecting a sound in the muffling area. , And an active muffling control device, wherein the active muffling control device is configured to detect the sound in the muffling region detected by the muffling effect detecting means based on the detection output signals from the noise detecting means and the muffling effect detecting means. The sounding means is controlled so that the sound for active silencing reaching from the sounding means into the sound deadening area is a sound having a phase opposite to that of the noise in the sound deadening area and having the same sound pressure and wavelength so that the noise is minimized. Thus, in the active sound deadening device in the three-dimensional space configured to perform active sound deadening in the sound deadening region, the sound deadening effect detecting means can be installed at any position, and the active sound deadening control device and the sound deadening device can be installed. An active silencer in a three-dimensional space, characterized in that it is connected to a sound effect detecting means by a flexible movable parallel cord, a coaxial cable, an optical fiber or a signal transmitting means using an electric wave. 2. The active muffling apparatus in a three-dimensional space according to claim 1, wherein a plurality of sounding means are provided, and a plurality of muffling effect detecting means are installed in a local muffling area. 3. An active sound deadening system in a three-dimensional space according to claim 1, wherein a plurality of sound producing means are provided, and different sound deadening effect detecting means are installed in respective different local sound deadening areas. 4. A plurality of muffling effect detection means are installed at intervals of half or one third of the wavelength of noise to be muffled, and as a set of a plurality of localized muffling regions,
3. An active sound deadening system in a three-dimensional space according to claim 2, wherein one large local sound deadening region surrounding these sound deadening effect detecting means is formed. 5. The sounding means can also be installed at an arbitrary position, and a flexible movable parallel cord, a coaxial cable, an optical fiber, or a radio wave is used between the sounding means and the active sound deadening control device. Claim 1 connected by the signal transmission means
The active silencer in the three-dimensional space described in 2, 3, or 4. 6. The active sound deadening in the three-dimensional space according to claim 1, further comprising a sound guide tube which radiates a sound for active sound deadening generated from the sounding means into a three-dimensional space from a required position. apparatus. 7. The noise source is in an air conditioner, and the noise detecting means is provided in the air conditioner.
7. An active silencer in a three-dimensional space according to any one of 1 to 6.