WO2008034789A1

WO2008034789A1 - Arrangement having an active noise reduction system

Info

Publication number: WO2008034789A1
Application number: PCT/EP2007/059764
Authority: WO
Inventors: Harry Bachmann; Sigmund Eggenberger
Original assignee: Anocsys Ag
Priority date: 2006-09-18
Filing date: 2007-09-17
Publication date: 2008-03-27

Abstract

Arrangement having an active noise reduction system in a space (1) which is equipped with at least one window (13) and outside of which there is an external region (2), wherein the window (13) has at least one glass pane (11, 14), and the active noise reduction system is composed of at least two sensor units (21, 26), at least one actuator unit (25) and at least one processing unit (20) which is operatively connected to the at least two sensor units (21, 26) and the at least one actuator unit (25). The invention is defined by the fact that at least one sensor unit (26) and at least one actuator unit (25) are arranged on the at least one glass pane (11, 14). This provides for the first time a way of implementing efficient, reliable and cost-effective solutions for active noise reduction in a space (1).

Description

Arrangement with an active noise reduction system

The present invention relates to an arrangement with an active noise reduction system according to the preamble of claim 1.

Noise sources are increasingly perceived as an environmental impact and are considered to reduce the quality of life. In particular, noise is also disturbing in

Living spaces and business premises. However, as noise sources are often unavoidable, noise reduction methods based on the principle of wave cancellation have already been proposed.

The principle of Active Noise Canceling (ANC) is based on the cancellation of sound waves due to interference. These interferences are generated by one or more electro-acoustic transducers, such as loudspeakers. The signal radiated by the electro-acoustic transducers is calculated by means of a suitable algorithm and continuously corrected. The basis for the calculation of the signal to be radiated by the electro-acoustic transducers is the information supplied by one or more sensors. These are on the one hand information about the nature of the signal to be minimized. For this purpose, for example, a microphone can be used which detects the noise to be minimized. On the other hand, but also information about the remaining residual signal needed. Again, microphones can be used.

The basic principle used with active noise reduction was Paul Lueg in a patent specification from the year 1935 with the disclosure number AT-141998 B described. By this document is disclosed how noise in a tube can be extinguished by generating a signal with opposite phase.

An active noise reduction system requires information from at least one sensor (for example, a microphone) that determines the residual error. Depending on the application and the algorithm used, additional sensors are provided that provide information about the nature of the signal to be minimized. Further, an active noise reduction system requires one or more actuators (eg, in the form of loudspeakers) to output the correction signal. The information from the sensors must be converted from an analog-to-digital converter into a digital format. After being processed by the algorithm, the signal is retransmitted by a digital-to-analog converter and transmitted to the actuators.

The effectiveness and efficiency of an active noise reduction system in a room now depends, among other factors, such as computing power and processing speed, also substantially on the acoustic properties of the actuators (for example from speakers). Thus, in the case of the loudspeakers, a spatially uniformly distributed radiation behavior and a sound distribution that is as uniform as possible in a room to be quieted should be aimed at, the acoustic distortions should be kept low, and the ripple of the frequency response should be as small as possible.

The bandwidth over which a noise reduction can be achieved is determined by the acoustic transit time between the actuator and the sensor. Since the bandwidth is inversely proportional to the transit time, it is advantageous for an active noise reduction system to place a sensor and an actuator close to each other, the effectiveness of this measure with respect to the achieved noise reduction, especially at low frequencies (preferably in the range below 300 Hz). , shows. One known application of this principle is, for example, a headphone with an active noise reduction system which employs a feedback method involving a classical control loop. The microphone signals are routed via a suitable controller to a speaker. As a result, background noise when listening to music can be reduced by several dB.

In a feedforward method, the signals from additional reference sensors (eg, microphones) are routed to the speakers via an adaptive processing unit employing an adaptive algorithm, such as by Sen M. Kuo and Dennis R. Morgan in the publication with the title "Active Noise Control: A Tutorial Review" (Proceedings of the IEEE, Vol. 87, No. 6, June 1999, p.955).

For the correct and reliable functioning of an active noise reduction system are the choice of

Actuators and sensors and the spatial placement of these elements, taking into account installation technical and aesthetic criteria crucial.

The object of the present invention is therefore to provide an arrangement of actuator and sensor units, so that the above criteria are optimally met.

This object is achieved by the features stated in the characterizing part of claim 1. Advantageous embodiments are specified in further claims.

The invention relates to an arrangement with an active noise reduction system in a room equipped with at least one window, outside of which there is an outside area. The window has at least one glass pane, and the active noise reduction system consists of at least two sensor units, at least one actuator unit and at least one processing unit, which is operatively connected to the at least two sensor units and the at least one actuator unit. The invention is characterized in that at least one sensor unit and at least one Actuator are arranged on one of the at least one glass sheet.

The window is used as a panel, passing through the diffuse and even spatial

Radiation properties a largely homogeneous sound field is generated. The inventive arrangement is characterized in particular by the fact that a predominantly frequency-independent radiation behavior is achieved, and that no membrane resonances occur. The

Window is vibrated so that as many of the eigenmodes are excited. Glass panes have sufficient rigidity to achieve this. The excitation takes place via electrodynamic transducers as actuator units, which excite the entire inner structure of the window or its glass panes to bending vibrations, which causes a diffused and spatially evenly distributed radiation behavior. The waviness remains low due to the dispersivity of the bending waves over the entire range. Due to the vanishingly small deflections of the glass panes, the restoring forces always remain in the linear range. In the arrangement according to the invention, the sound pressure decreases to a lesser extent with increasing distance, thus achieving the most uniform possible sound distribution in the room.

The present invention also has the advantage that disturbing noises are already minimized at the source, So before disturbing noises in the room can spread according to the laws of physics.

An embodiment of the arrangement according to the invention consists in that at least one actuator unit is arranged on a surface of the at least one glass pane of the window facing the space.

A further embodiment of the arrangement according to the invention consists in that at least one sensor unit is arranged on a surface of the at least one glass pane of the window facing the outside area.

A further embodiment of the arrangement according to the invention consists in that the window has at least two glass panes and that the at least two glass panes form a gap.

A further embodiment of the arrangement according to the invention consists in that an actuator unit in

Interspace, preferably arranged on a surface of the space facing glass pane.

A further embodiment of the arrangement according to the invention is that a sensor unit in

Interspace, preferably arranged on a surface of the outer region facing glass pane. A further embodiment of the arrangement according to the invention consists in that an acceleration sensor is arranged on a glass pane.

Another embodiment of the inventive

Arrangement consists in that a strain gauge is arranged on a glass sheet.

A further embodiment of the arrangement according to the invention consists in that the acceleration sensor and / or the strain gauge are arranged on the surface of the glass pane facing the outside area and / or in the space on the surface of the glass pane facing the space.

A further embodiment of the arrangement according to the invention consists in that means for reducing noises are present by means of a feedback method.

A further embodiment of the arrangement according to the invention consists in that means for reducing noises are present by means of a feedforward method.

A further embodiment of the arrangement according to the invention consists in that a plurality of actuator units are provided on the window, which are arranged in a basic pattern formed of squares, wherein the actuator units are placed in the corners of the squares. A further embodiment of the arrangement according to the invention consists in that side lengths of the squares correspond to half the wavelength of a noise to be reduced.

Hereinafter, the present invention will be further explained by way of embodiments with reference to drawings. Show it:

Fig. 1 is a plan view of a room with a known active noise reduction system in a schematic

Presentation,

FIG. 2 is a simplified block diagram of a known noise reduction system employing a known feedback method. FIG.

Fig. 3 is a simplified block diagram of an active noise reduction system, wherein a known

Feedforward method is applied

Fig. 4, again in a schematic representation, the space according to FIG. 1 with an active noise reduction system and a window, in

Reference to which an actuator unit and a sensor unit are arranged according to the invention,

5 shows a detail in the region of the window with an active noise reduction system and a further inventive arrangement variant of the sensor and actuator units, again in a schematic representation,

6 shows the detail according to FIG. 5 with a still further arrangement variant of the sensor and actuator units according to the invention, and FIG

7 shows the window in frontal view with a further arrangement variant according to the invention of FIG

Actuator units on the window, again in a schematic representation.

Fig. 1 shows a space 1 in plan with a known active noise reduction system, which consists of a processing unit 20, which is operatively connected via the electrical connections 19 with a sensor unit 21 (for example, a microphone) for detecting the residual noise within the room 1. Furthermore, the processing unit is provided with a

Actuator 24 (for example, a speaker) operatively connected to the output of a correction signal. To detect disturbing external noises, which may be present in a region 2 outside the room 1, a microphone 22 is provided in the region 2.

Fig. 2 shows a block diagram of a known active noise reduction system in which a known feedback method is used. An output signal of a microphone 26 is a processing unit 27th which generates a correction signal which is supplied to a speaker unit 25.

Fig. 3 shows, again in a simplified representation, a block diagram of an adaptive noise reduction system to which a known feedforward method is applied. A space 1 to be monitored, which can be represented by a transfer function H, contains a microphone unit 7 acted upon by an input signal x and a loudspeaker unit 9 with which a signal y is generated. The transfer function H describes the acoustic behavior of the room 1 (FIG. 1). In addition to the acoustic behavior, transmission characteristics H of the components used, such as the microphone unit 7 and the loudspeaker unit 9, are also contained in the transfer function H. The active noise reduction system according to FIG. 3 further comprises a filter 3, which contains a model of the actual transfer function H, an adaptive unit 4 in which an adaptive algorithm is processed, and an addition unit 5, the input signal x next to the microphone unit 7 is acted upon both the filter 3 and the adaptive unit 4. To form an error signal e, an actual output d produced by the transfer function and an output y estimated by the filter 3 are counted together in the adding unit 5, the estimated output y being previously inverted to obtain the deviation of the two output signals d and y. The error signal e is applied to the adaptive unit 4, in which, for example, an Fx algorithm is used to control the filter 3.

FIG. 4 shows a schematic representation of the space 1 according to FIG. 1 with an active noise reduction system and with a window 13 which forms a region of a wall 23 delimiting the space 1. According to the invention, an actuator unit 25 and a sensor unit 26 are arranged in the region of the window 13. The window 13 in one embodiment consists of double glazing, i. the window 13 consists of two substantially parallel glass panes 11 and 14, wherein the glass pane 14 faces the room 1 and wherein the glass pane 11 faces the environment. In contrast to FIG. 1, the actuator unit 25 shown in FIG

Output of the correction signal is disposed on the glass plate 14, on the room-side surface of the glass sheet 14. The actuator unit 25 is also operatively connected via the electrical connection 19 to the processing unit 20. The also to the

Processing unit 20 connected sensor unit 26 (for example, a microphone) is used to detect the external noise and is according to the invention on the outside of the glass pane 11 of the window 13, ie outside of space 1, respectively.

The sensor unit 21 is used to detect the residual noise within the room 1. The generation of the correction signal, via the actuator unit 25 to the inside of the Glass pane 14 of the window 13 is transmitted, carried out according to the feedback method described in Fig. 2.

In a further embodiment of the present invention, the correction signal by means of a

Feedforward process according to FIG. 3 generated and in turn delivered to the actuator unit 25.

In a further embodiment it is provided that instead of a double glazing, as is the case with the window 13 shown in FIG. 4, a single glazing is used. In this case, the actuator unit 25 and the sensor unit 26 are arranged on the same glass pane, but on opposite disk surfaces. Thus, the actuator unit 25 is disposed on the inner surface and the sensor unit 26 on the outer surface of the glass sheet.

5 shows, again in a schematic illustration, a section of the space 1 in the region of the window 13, wherein, according to a further arrangement variant of the present invention, further sensor and actuator units 25 'and 26' are provided. However, some of the components of the active noise reduction system, although present, are not apparent in FIG. 5 because of the area-only representation. This is in particular the sensor unit 21.

As in the embodiment variant shown in FIG. 4, the window 13 of the embodiment according to FIG. 5 a double glazing with two glass panes, namely an inner glass pane 14 facing the space 1 and an outer glass pane 11 facing the outer area 2. The window 13 is installed in a masonry 12, 12 'via a window frame 10, 10'. Between the inner and the outer glass pane 14 and 11, a gap 15 is provided, which is filled, for example, with air or other media commonly used in double glazing.

In the intermediate space 15, the further sensor unit 26 'and the further actuator unit 25' are contained depending on the still to be explained embodiments, wherein the further sensor unit 26 'on the outer glass 11 and the further actuator unit 25' on the inner glass pane 14 are arranged.

In one embodiment of the present invention, on the surface of the glass pane 14 facing the space 1, the actuator unit 25 is mounted directly on the glass pane 14 for the purpose of sound transmission. The sound emission takes place with highly diffuse properties through the glass pane 14 into the space 1. The connected to the processing unit 20 further sensor unit 26 (for example, a microphone) is used for

Detection of external noise and according to the invention is placed on the outer area 2 located outside of the glass pane 11 of a window. In a further embodiment variant, the placement of the further actuator unit 25 'and the further sensor unit 26' takes place in the intermediate space 15 of the window 13, that is to say between the two glass panes 11 and 14.

In yet another embodiment of the present invention, the placement of the further actuator unit 25 'and the further sensor unit 26' takes place either on the outer glass pane 11 or on the inner glass pane 14, wherein both the further

Actuator 25 'and the other sensor unit 26' in the space 15 of the window 13 are located.

FIG. 6 essentially shows the detail according to FIG. 5 with the window 13, which has a double glazing with the two glass panes 11 and 14 forming the intermediate space 15. In addition to the sensor unit 26 (for example a microphone) for detecting external noises described in FIG. 5, an acceleration sensor 29 and a strain gauge 28 are arranged as additional sensor units for detecting vibrations generated by sound on the outer glass pane 11 facing the outer area 2 of the window 13 are provided.

In a further embodiment of the present invention, it is provided to arrange the further actuator unit 25 'and the further sensor units 26', 28 ', 29' in the intermediate space 15 of the window 13. It is to be expressly understood that the present invention can also be excellently applied to windows having more than two panes of glass, so-called composite windows. It does not matter at which point the space is provided.

7 shows the window 13 with a window frame 16 in a frontal view, wherein the actuator units 18-for example loudspeakers-are arranged on the glass pane 17 in accordance with a square basic pattern. The actuator units 18 are respectively placed in the corners of the squares forming the basic pattern, whose side lengths preferably each correspond to a half wavelength λ / 2 of the noise to be reduced.

For example, with a noise at a frequency of 500Hz, the side length of the squares forming the basic pattern is 34cm long, which is half the wavelength of the sound. With such an arrangement can also be advantageously a sound reduction of

To achieve noises with a fundamental frequency greater than about 400 Hz. It is expressly pointed out that the number of actuator units 18 depends on the size of the glass pane 17 and the desired noise reduction.

In accordance with the embodiment variants according to FIGS. 5 and 6, the actuator units 18 can, according to the embodiment shown in FIG. 7, be provided on the surface of the outer pane facing the outer region 2 as well as in the Interspace of a double-glazed window can be arranged. In the latter case, the actuator units 18 are also arranged on the outer glass pane.

Claims

claims

An arrangement with an active noise reduction system in a space (1) equipped with at least one window (13) outside which there is an outside area (2), the window (13) comprising at least one glass pane (11, 14) and the active noise reduction system consists of at least two sensor units (21, 22, 26, 26 ', 28, 28', 29, 29 ') _/ at least one actuator unit (18, 24, 25, 25') and at least one processing unit (20) associated with the at least two sensor units (21, 22, 26, 26 ', 28, 28', 29, 29 ') and the at least one actuator unit (18, 24, 25, 25') is operatively connected, characterized in that at least one sensor unit (26 , 26 ', 28, 28', 29, 29 ') and at least one actuator unit (18, 25, 25') are arranged on one of the at least one glass pane (11, 14).

2. Arrangement according to claim 1, characterized in that at least one actuator unit (25) on a space (1) facing surface of the at least one glass pane (14) of the window (13) is arranged.

3. Arrangement according to claim 1 or 2, characterized in that at least one sensor unit (18, 26) on a the outer region (2) facing surface of the at least one glass pane (14) of the window (13) is arranged.

4. Arrangement according to one of claims 1 to 3, characterized in that the window (13) has at least two glass panes (11, 14) and that the at least two glass panes (11, 14) form a gap (15).

5. Arrangement according to claim 4, characterized in that an actuator unit (25 ') in the intermediate space (15), preferably on a surface of the space (1) facing glass pane (14) is arranged.

6. Arrangement according to claim 4 or 5, characterized in that a sensor unit (26 ') in the intermediate space (15), preferably on a surface of the outer region (2) facing glass pane (11) is arranged.

7. Arrangement according to one of claims 1 to 6, characterized in that an acceleration sensor (29, 29 ') on a glass pane (11, 14) is arranged.

8. Arrangement according to one of claims 1 to 7, characterized in that a strain gauge (28, 28 ') on a glass pane (11, 14) is arranged.

9. Arrangement according to claim 7 or 8, characterized in that the acceleration sensor (29, 29 ') and / or the strain gauges (28, 28') on the outer region (2) facing surface of the glass sheet (11) and / or Space (15) on the space (1) facing surface of the glass sheet (11) are arranged.

10. Arrangement according to one of claims 1 to 9, characterized in that means for reducing noise by means of a feedback method are provided.

11. Arrangement according to one of claims 1 to 9, characterized in that means for reducing noise by means of a feedforward method are provided.

12. Arrangement according to one of claims 1 to 11, characterized in that a plurality of actuator units (18) on the window (13) are provided, which are arranged in a pattern formed from squares, wherein the

Actuator units (18) are placed in the corners of the squares.

13. Arrangement according to claim 12, characterized in that side lengths of the squares correspond to half the wavelength of a noise to be reduced.