JPH0594898U - Active noise reduction device - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain an active noise reduction device that saves space without blocking light. An active noise control device configured to use a transparent speaker having a transparent diaphragm and transparent electrodes as a silencer. With this configuration, it is possible to effectively use the car and the living space.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention is an active method that artificially generates a sound wave having the same amplitude as a phase opposite to that of the propagated sound wave (hereinafter referred to as “propagated noise”) from a noise source and muting the sound wave and the propagated noise by mutual interference. The present invention relates to a noise reduction device.

[0002]

[Prior Art]

 FIG. 6 is a principle diagram of a conventional active noise reduction system for a vehicle disclosed in, for example, TI TECHNICAL SPOT No.8 (1990-9). In the figure, the vibration source 2, which is the first mechanical-electrical converter, is installed in the engine that is the noise source 1, and the noise reduction effect is applied to the head of the person in the passenger compartment, that is, the area where noise reduction is desired. A plurality of microphones 3, which are second electromechanical converters for evaluation, are installed. Furthermore, a plurality of muffling speakers 4, which are electromechanical converters, are provided in the passenger compartment so as to surround a region where a person sits. Further, in FIG. 1, a control device 5 is provided between the vibration pick-up 2 which is the first electromechanical converter and the electromechanical converter 4.

Next, the operation will be described. In the above configuration, the propagation noise from the engine, which is the noise source 1, is first detected by the vibration pickup 2 as mechanical vibration having a correlation with the propagation noise, converted into an electric signal and input to the control device 5. Further, an evaluation signal for evaluating the muffling effect from the plurality of microphones 3 is input to the control device 5. The control device 5 drives the microphone 3 so that the output of the microphone 3 becomes zero due to the mutual interference between the sound waves for silencing emitted from the silencing speaker 4 and the propagation noise in the installation area of the microphones 3, that is, in the vicinity of the human head. The signal is output to each muffling speaker 4. With this configuration, it is possible to suppress the propagation noise in the installation area of the plurality of microphones 3.

[0004]

[Problems to be solved by the device]

 Since the conventional active noise reduction device is configured as described above, many muffling speakers must be arranged in a narrow space inside the vehicle. In addition, since the sound wave propagating from the engine, which is the noise source 1, has a low frequency of 20 to 100 Hz, the cabinet capacity of the speaker also becomes large. As a result, there was the problem that the vehicle interior space would become even smaller.

The present invention has been made to solve the above-mentioned problems, and a large number of speakers with large cabinets are installed in a vehicle compartment by installing a transparent sound-deadening speaker on the window glass of the vehicle. It is an object of the present invention to provide an active noise reduction device that reduces engine noise in the passenger compartment without any problem.

[0006]

[Means for Solving the Problems]

 The active noise reduction device according to the present invention uses a transparent electro-optical ceramics material such as PLZT (lanthanum-substituted lead zirconate titanate) as the diaphragm material of the noise reduction speaker, and a transparent conductive film such as PLZT (lanthanum-substituted lead titanate). A transparent piezoelectric speaker made of ITO (indium oxide), tin oxide, etc. is provided on the window glass of a car.

[0007]

[Action]

 The active noise reduction device according to the present invention uses a transparent speaker as a muffling speaker and is installed on the window glass of the vehicle. Therefore, the engine noise is reduced without saving the space in the vehicle compartment and further hindering the visibility. Is.

[0008]

【Example】

 Example 1. 1 which is one embodiment of the present invention will be described below. In the figure, a noise pickup 1 such as an engine of a car is provided with a vibration pickup 2 which is a first electromechanical converter, and the vibration pickup 2 is installed in the passenger's head in the passenger compartment, that is, in an area where noise reduction is desired. Is equipped with a plurality of microphones 3 which are second electromechanical converters for evaluating the muffling effect. Further, on the window glass of the car, a plurality of transparent speakers 4 are provided at the front, the rear, and the side so as to surround the head area of the seat, as a sound-suppressing speaker that is an electromechanical converter, and do not block the view. Has been. Further, in FIG. 1, a control device 5 is provided between the vibration pickup 2 which is the first electromechanical converter and the electromechanical converter 4.

Next, the operation of the present invention will be described. In the above configuration, the propagation noise from the engine which is the noise source 1 is first detected by the vibration pickup 2 as mechanical vibration that correlates with the propagation noise, converted into an electric signal and input to the control device 5. The control device 5 also converts the sound wave synthesized by the mutual interference between the engine propagation noise from the microphones 3 and the sound deadening sound wave from the transparent speaker 4, that is, the evaluation signal for evaluating the sound deadening effect into an electric signal. Is input. The control device 5 first receives the signal from the vibration pickup 2 and generates a sound wave signal for muffling, which has the same amplitude and an opposite phase, and outputs it to a plurality of transparent loudspeakers 4 installed on the window glass of the car, which is a muffling speaker. To do. The plurality of transparent speakers 4 convert the electric signal into a mechanical signal and emit a sound wave for silencing. Here, the propagating noise and the sound wave for silencing interfere with each other and are synthesized, but due to differences in acoustic conditions in the propagating path, the sound is not muted sufficiently. Therefore, feedback is applied to the control device 5 so that the outputs of the plurality of microphones 3 for evaluation of the muffling effect are set to zero, the drive signal is again given to the plurality of transparent speakers 4, and this operation is repeated to repeat the operation. It is possible to obtain a sufficient silencing effect in the human head area. By using a transparent sound-deadening speaker for the window glass of a car, it is possible to further reduce the space without hindering the view.

Example 2. In addition, FIG. 2, which is an embodiment of the present invention, will be described. Although the configuration is almost the same as that in Fig. 1, the active noise reduction device is applied to a building by installing a transparent speaker 4 which is a muffling speaker on a window glass of the building or the like. In the case of a building, noise from the outside noise source 1 has a small sound insulation characteristic, that is, a large amount of penetration from the window glass part with a small acoustic impedance, so noise can be effectively reduced by installing a noise reduction speaker on the window glass. It becomes possible. In addition, since it is a transparent speaker, it does not block external light, and there is no need to specially secure a space for a silent speaker. Here, the transparent speaker is provided on the window glass, but it may be a glass for a door or a window.

Regarding operation, the first microphone is installed near the window glass of the building as the mechanical-electrical converter for detecting the propagation noise of FIG. 1, and the second microphone, which is the mechanical-electrical converter for silencing evaluation, is installed. Since it is installed in the lighting equipment in the building, a transparent speaker that is a sound-deadening speaker is installed on the window glass, and the control device is installed on the ceiling part, the operation is the same, so it is omitted. The installation locations of the first and second microphones and the control device are not limited to particular places.

Example 3. In addition, FIG. 3, which is an embodiment of the present invention, will be described. 3 has almost the same configuration as that of FIG. 2, but an active noise reduction device is applied to a building fixture by installing a transparent speaker 4 which is a muffling speaker in a lighting fixture for the building. In order to further limit the noise reduction area and make noise reduction more effective than in the case of Fig. 2, a lighting device is placed in a specific place where people can talk, and a transparent speaker, which is a noise reduction speaker, is installed in this lighting device. Is installed and integrated. By using a transparent speaker, it is possible to integrate the control device and microphone without blocking the illumination light. Also, the power supply for the control device and the like becomes simple.

Regarding the operation, the first microphone for detecting the propagation noise of FIG. 2 is installed in the vicinity of the window glass of the building, and the second microphone for noise reduction evaluation, the transparent speaker as the noise reduction speaker and the control are provided. Since the operation is the same only when the device is installed in the luminaire, it is omitted. The installation locations of the first and second microphones and the control device are not particularly limited.

Example 4. Further, FIG. 4, which is an embodiment of the present invention, will be described. 4 has almost the same configuration as that of FIG. 3, but an active noise reduction device is adapted to a building fixture by installing a transparent speaker 4 which is a muffling speaker as a table or a rug on a desk for the building. It was used. The same effect as in the case of FIG. 3 is obtained.

As for the operation, the first microphone for detecting the propagation noise shown in FIG. 3 is installed near the window glass of the building, the second microphone for silencing evaluation and the control device are used for the lighting equipment, and the silencing speaker is used. Since a certain transparent speaker is installed as a rug on the table, the operation is the same and thus omitted. The installation locations of the first and second microphones and the control device are not particularly limited.

Example 5. In addition, FIG. 5, which is an embodiment of the present invention, will be described. 5 has almost the same configuration as that of FIG. 1, but an active noise reduction device is applied to a telephone box by installing a transparent speaker 4 which is a muffling speaker on the window glass and door of the telephone box. The same effect as in the case of FIG. 1 is obtained.

As for the operation, the first microphone is installed near the window glass of the telephone box as a mechanical-electrical converter for detecting the propagation noise of FIG. 1, and the second microphone for noise reduction evaluation is installed in the ceiling portion of the telephone box. The operation is the same because the transparent speaker, which is a silent speaker, is installed on the window glass and door of the telephone box, and the control device is installed on the ceiling. The installation locations of the first and second microphones and the control device are not particularly limited.

Example 6. We have shown an active noise reduction device that applies a transparent speaker to the entire surface such as a window glass for a car, but it may be a part of the window glass, and there is no need to limit the number of microphones, transparent speakers for noise reduction, and control devices. An active noise reduction device that generates a sound wave for silencing having the same amplitude and an opposite phase to the propagating noise and mutes the sound by mutual interference with the propagating noise is sufficient.

[0019]

[Effect of the device]

 As described above, according to the present invention, the use of the transparent speaker as the muffling speaker has the effect of obtaining the active noise reduction device that can save the space of the vehicle or the living space without blocking the light.

[Submission date] March 26, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

[Prior Art]

FIG. 6 is a principle diagram of a conventional active noise reduction system for a vehicle disclosed in, for example, TI TECHNICAL SPOT No.8 (1990-9). In the figure, the engine that is the noise source 1 is equipped with the vibration pickup 2 that is the first electromechanical converter, and the noise reduction effect is provided in the head of the person in the passenger compartment, that is, in the area where noise reduction is desired. A plurality of microphones 3, which are second electromechanical converters for evaluation, are installed. Furthermore, a plurality of muffling speakers 4 which are electromechanical converters are provided in the passenger compartment so as to surround a region where a person sits. Further, in FIG. 6 , a control device 5 is provided between the vibration pick-up 2 which is the first electromechanical converter and the electromechanical converter 4.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

[0008]

【Example】

Example 1. 1 which is one embodiment of the present invention will be described below. In the figure, a vibration pickup 2 which is a first electromechanical converter is installed in a noise source 1 such as an engine of a vehicle, and the vibration is picked up in a head portion of a person in a passenger compartment, that is, in an area where noise reduction is desired. Is equipped with a plurality of microphones 3 which are second electromechanical converters for evaluating the muffling effect. Further, on the window glass of the car, a plurality of transparent speakers 4 are provided at the front, rear, and side surfaces so as to surround the head region of the seat as a sound-suppressing speaker that is an electromechanical converter and that does not block the view. Has been. Further, in FIG. 1, a control device 5 is provided between the vibration pickup 2 which is the first electromechanical converter and the electromechanical converter 4.

[Brief description of drawings]

FIG. 1 is a system diagram of an active noise reduction device showing a first embodiment of the present invention.

FIG. 2 is a system diagram of an active noise reduction device showing a second embodiment of the present invention.

FIG. 3 is a system diagram of an active noise reduction device showing a third embodiment of the present invention.

FIG. 4 is a system diagram of an active noise reduction device showing a fourth embodiment of the present invention.

FIG. 5 is a system diagram of an active noise reduction device showing a fifth embodiment of the present invention.

FIG. 6 is a system diagram of a conventional active noise reduction device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Noise source 2 1st electromechanical converter 3 2nd electromechanical converter 4 Electromechanical converter 5 Control device

Claims (1)

[Scope of utility model registration request] 1. A first electromechanical converter provided for detecting a sound wave propagating from a noise source, and a sound wave having a phase opposite to that of the sound wave propagating from the noise source and having the same amplitude and radiating the sound wave. An electromechanical converter for silencing a sound wave propagating from the noise source due to interference, and a second electromechanical converter for detecting a composite sound wave of the sound wave propagating from the noise source and the sound wave radiated from the electromechanical converter. And receiving an output signal of the first electromechanical converter, generating a signal having characteristics of opposite phase and the same amplitude, and making the output signal of the second electromechanical converter zero. In an active noise reduction device composed of a control device for controlling a drive signal of an electromechanical converter, a transparent speaker composed of a transparent diaphragm and transparent electrodes is used as the electromechanical converter. Active noise reduction device.