Acoustic insulation system

Abstract

Acoustic insulation system (1) usable for acoustically insulating a protected environment (100) from an external environment (200), the system (1) comprising: - a first transparent pane (2) and a second transparent pane (3), parallel and distanced; - at least a third transparent pane (4) having a lower thickness with respect to the first pane (2) and to the second pane (3), the third pane (4) being interposed between the first pane (2) and the second pane (3) so as to define two chambers or gaps (5, 6); - at least one vibro-acoustic transducer (9) applied to the third pane (4) and configured to emit a vibration signal at a frequency comprised between 100 Hz and 6000 Hz; - a signal generator (20) configured to send to the vibro-acoustic transducer (9) signals to be reproduced; - a control unit (10) configured to control the signal generator (20).

Description

[0001] DESCRIPTION

[0002] ACOUSTIC INSULATION SYSTEM

[0003] Field of the art

[0004] The present invention relates to an acoustic insulation system usable for acoustically insulating an environment, specifically to protect it against eavesdropping by means of laser microphones.

[0005] In particular, the proposed invention can be used in the acoustic insulation of civil, residential, industrial, government and military buildings and in the transport sector.

[0006] Prior art

[0007] The problem of security of information shared during private conversations is becoming increasingly important, due to the significant progress in the development of laser eavesdropping techniques. In this area, laser microphones allow eavesdropping of sounds and conversations inside closed environments, even from large distances.

[0008] In general, glass walls and windows are elements that are highly vulnerable to laser eavesdropping techniques.

[0009] The human voice does, in fact, generate sound waves that interact with the surrounding objects, making them vibrate; these vibrations can be detected through laser vibrometers and converted into an audio track through appropriate processing of the signal. Laser microphones, by emitting a laser beam pointed towards the window, can therefore detect the vibrations of the glass wall, or of objects inside the room, which are converted into audio tracks, thus allowing eavesdropping of the conversations inside the room.

[0010] Two typical scenarios exist: a) the laser beam is pointed onto a vibrating object inside the room in which the conversation is taking place (the object should preferably have a smooth and reflective surface, for example a picture hanging on the wall or a mirror); b) the laser beam is bounced off the window itself, which vibrates in response to the pressure waves created by the noises in the room.Passive and active solutions have been proposed to mitigate the risk of eavesdropping by means of laser microphones.

[0011] Several examples of passive solutions on the market are:

[0012] - special films to be applied to the panes of glass to damp the vibrations thereof;

[0013] - surface treatments to modify the efficacy of the laser vibrometer and disturb eavesdropping;

[0014] - multilayer laminated panes of glass designed to reduce their own vibration within the range of frequencies concerned;

[0015] - fabric curtains and screens made of materials designed to reduce the passage of the laser beams.

[0016] However, the efficacy of the passive solutions is not sufficient.

[0017] In particular, the passive solutions of the glass type are extremely bulky and do not achieve, in any case, a high level of protection against eavesdropping.

[0018] Curtains, and coverings in general, force the room to be kept dark.

[0019] The active solutions include the use of transducers mounted on walls, floors, ceilings, windows and in other structures of the room which, when connected to a signal generator, are capable of causing the structures to vibrate, making eavesdropping ineffective.

[0020] These solutions are described, for example, in the scientific article entitled “Research on Anti-Laser-Eavesdropping Devices", by Fan Yan-Hong et al., 2012 International Conference on Industrial Control and Electronics Engineering, Xi'an, China, pp. 1981-1983, 2012.

[0021] In practical terms, the active solutions are based on systems for the generation of noise serving to mask voice signals, so they require additional components to be installed in the room and have problems linked to maintenance, to redesign of the environment and to the possible noise generated.

[0022] Transducers applied directly on glass walls have not been demonstrated to be effective on commercial glass walls, particularly if they have largedimensions.

[0023] Furthermore, the active devices are not always capable of protecting against the possibility of eavesdropping of conversations from the vibrations of internal objects.

[0024] Object of the invention

[0025] In this context, the technical task underlying the present invention is to propose an acoustic insulation system capable of efficiently protecting the confidentiality and privacy of a protected environment, in particular by preventing or counteracting eavesdropping with laser microphones.

[0026] In particular, an object of the present invention is to provide an acoustic insulation system that has easy installation and maintenance, even in preexisting environments.

[0027] Another object of the present invention is to provide an acoustic insulation system that is adaptable to the different levels of confidentiality required by the specific applications.

[0028] The stated technical task and the specified objects are substantially achieved by an acoustic insulation system usable for acoustically insulating a protected environment from an external environment, said system comprising:

[0029] - a first transparent pane and a second transparent pane, said first pane and said second pane being distanced from and parallel to each other, said first pane being positionable towards the protected environment and said second pane being positionable towards the external environment;

[0030] - at least a third transparent pane interposed between said first pane and said second pane so as to define a first chamber delimited by the first pane and by the third pane and a second chamber delimited by the second pane and by the third pane, said third pane having a lower thickness with respect to the first pane and to the second pane;

[0031] - a frame on which said panes are mounted;

[0032] - at least one vibro-acoustic transducer applied to the third pane andconfigured to emit a vibration signal at a frequency comprised between 100 Hz and 6000 Hz;

[0033] - a signal generator coupled to said at least one vibro-acoustic transducer to send to the vibro-acoustic transducer signals to be reproduced;

[0034] - a control unit configured to command the signal generator to generate signals to be sent to the vibro-acoustic transducer;

[0035] - a system of gaskets between frame and panes, made of a soft material.

[0036] In accordance with an aspect of the invention, the third pane has a thickness comprised between 0.5 mm and 1 mm.

[0037] In one embodiment, a reflective coating is applied to the third pane.

[0038] In particular, the vibro-acoustic transducer is of the magnetodynamic type. For example, the vibro-acoustic transducer is applied to a peripheral zone of the third pane, close to an edge of the third pane.

[0039] The vibro-acoustic transducer is installed on the third pane by means of gluing, or magnetic coupling or by means of adhesive or by means of one or more suction cups.

[0040] In accordance with one embodiment of the invention, the control unit is configured to command the signal generator to generate a predefined signal.

[0041] In accordance with one embodiment of the invention, the control unit is configured to command the signal generator to generate a signal in response to the receipt of an audio signal relating to the protected environment.

[0042] In one embodiment, the system further comprises a receiver mounted on the first pane or on an outer side of the frame facing the protected environment. The receiver is configured to detect audio signals. In response to the receipt of an audio signal from the receiver, the control unit is configured to command the signal generator to generate a signal having frequency and amplitude such as to cancel or to mask the audiosignal coming from the receiver.

[0043] In a variant embodiment, the system further comprises a further vibroacoustic transducer applied to the third pane. The receiver, the control unit, the signal generator, the vibro-acoustic transducer and the further vibro-acoustic transducer define a closed-loop control chain.

[0044] In one embodiment of the invention, the system comprises one or more additional transparent panes interposed between the first pane and the third pane and / or between the third pane and the second pane. In this manner, further chambers or gaps are defined, each delimited by a pair of panes.

[0045] Brief description of the drawings

[0046] Further features and advantages of the present invention will become more apparent from the indicative and thus non-limiting description of a preferred but non-exclusive embodiment of an acoustic insulation system, as illustrated in the attached drawings, in which:

[0047] - Figure 1 depicts an acoustic insulation system, in accordance with the embodiment of the present invention, in a sectional view;

[0048] - Figure 2 shows the acoustic insulation system of Figure 1 , in a front view, in which a possible arrangement of the vibro-acoustic transducers can be seen;

[0049] - Figure 3 illustrates the block diagram of an open-loop control actuated by the acoustic insulation system, in accordance with the present invention;

[0050] - Figures 4 and 5 illustrate block diagrams of two different types of control, possibly in feedback, actuated by the acoustic insulation system, in accordance with the present invention.

[0051] Detailed description of preferred embodiments of the invention With reference to the figures, number 1 indicates an acoustic insulation system, hereinafter briefly referred to as “system”.

[0052] The system 1 is usable for acoustically separating a protected environment, in which it is intended to maintain confidentiality and privacy,from an external environment.

[0053] For example, the protected environment, indicated with the number 100, can be a company room, a public office, a residential room. The external environment, indicated with the number 200, is a room or space adjacent to the protected environment 100, or the outdoors.

[0054] The system 1 comprises a first transparent pane 2 and a second transparent pane 3, which are distanced from and parallel to each other. In this context, the term "transparent" indicates that the pane has a light transmittance of at least 30%, calculated as indicated in EN 410:2011 and ISO 9050:2003.

[0055] For example, the first and the second pane 2, 3 are made of one of the following materials: soda-lime glass, borosilicate glass, aluminosilicate glass, acrylic glass, polycarbonate.

[0056] The first pane 2 and the second pane 3 can have different thicknesses or the same thickness.

[0057] For example, the thickness of the first and the second pane 2, 3 is comprised between 6 mm and 12 mm.

[0058] More preferably, the first pane 2 and the second pane 3 are identical. In particular, they have the same dimensions and are made of the same material.

[0059] The system 1 further comprises at least a third pane 4 interposed between the first pane 2 and the second pane 3. In particular, the third pane 4 is parallel to the first and to the second pane 2, 3.

[0060] The third pane 4 is distanced both from the first pane 2 and from the second pane 3.

[0061] Two chambers (or gaps) 5, 6 are therefore defined, i.e.:

[0062] - a first chamber (or gap) 5 delimited by the first pane 2 and by the second pane 4;

[0063] - a second chamber (or gap) 6 delimited by the second pane 3 and by the third pane 4.

[0064] The first chamber 5 and the second chamber 6 are filled with air or inertgas.

[0065] Preferably, the third pane 4 is equally distanced from the first pane 2 and from the second pane 3. According to this arrangement, the first chamber 5 and the second chamber 6 have the same volume.

[0066] The first pane 2 is positioned so as to be facing the protected environment 100 and the second pane 3 is positioned so as to be facing the external environment 200. For this reason, in this context the first pane 2 is also called the “inner pane”, whereas the second pane 3 is also called the “outer pane”.

[0067] Advantageously, the third pane 4 has a lower thickness than the first pane 2 and the second pane 3.

[0068] As will be seen below, such a choice allows the efficiency of the actuation and control system to be increased.

[0069] For example, the thickness of the third pane 4 is comprised between 0.5 mm and 1 mm.

[0070] For example, the third pane 4 is made of one of the following materials: soda-lime glass, borosilicate glass, aluminosilicate glass, acrylic glass, polycarbonate.

[0071] According to one aspect of the invention, all three panes 2, 3, 4 have a planar extension.

[0072] In a preferred embodiment, a reflective coating is applied to the third pane 4.

[0073] For example, such reflective coating is applied to one of the planar surfaces 4a, 4b of the third pane 4, preferably to the planar surface 4a facing the second chamber 6 (i.e. towards the external environment 200). Such planar surface 4a is also indicated as the “outer planar surface”, as it is facing the outer pane 3.

[0074] The other planar surface 4b, on the other hand, is indicated as the “inner planar surface”, as it is facing the inner pane 2.

[0075] As an alternative, such reflective coating is applied to both planar surfaces 4a, 4b of the third pane 4.The reflective coating, for example mirrored, serves to reflect any laser beams that could be emitted from the external environment 200 in the attempt to eavesdrop on the private communications in the protected environment 100.

[0076] The three panes 2, 3, 4 are mounted on a frame 7 or surrounding border. Preferably, the frame 7 has a recess configured to receive the edges 12a, 12b, 13a, 13b, 14a, 14b of the panes 2, 3, 4.

[0077] Preferably, a gasket or sealant 11 is interposed between the edges 12a, 12b, 13a, 13b, 14a, 14b of the panes 2, 3, 4 and the inside of the frame 7. The gasket 11 is made of a soft material, typically but not exclusively a silicone material.

[0078] The first pane 2 is maintained distanced from the third pane 4 by means of first spacers or separators 16. For example, the first separators 16 are made of a soft material, such as rubber or resins.

[0079] In particular, each of the first separators 16 is interposed between one of the edges 12a, 12b of the first pane 2 and one of the edges 14a, 14b of the third pane 4.

[0080] Similarly, the second pane 3 is maintained distanced from the third pane 4 by means of second spacers or separators 17.

[0081] Similarly to the first separators 16, the second separators 17 are also made of a soft material, such as rubber or resins.

[0082] In particular, each of the second separators 17 is interposed between one of the edges 13a, 13b of the second pane 3 and one of the edges 14a, 14b of the third pane 4.

[0083] In particular, the frame 7 is made of a sufficiently rigid material to provide support to the three panes 2, 3, 4. By way of example, the frame 7 can be made of PVC, aluminium, steel alloys, composite materials.

[0084] Advantageously, the system 1 comprises at least one vibro-acoustic transducer 9 applied to the third pane 4.

[0085] The vibro-acoustic transducer 9 is configured to emit a vibration signal at a frequency comprised between 40 Hz and 20000 Hz.More preferably, the frequency of the vibration signal is comprised between 100 Hz and 6000 Hz.

[0086] The vibrations emitted by the vibro-acoustic transducer 9 are such as to cause the third pane 4 to which it is applied to vibrate.

[0087] In practice, the vibro-acoustic transducer 9 is a magnetodynamic transducer capable of exciting the third pane 4 to which it is applied, transforming it into a sound source capable of masking the vibration induced by the sounds produced inside the environment 100.

[0088] The choice to have a thin third pane 4, i.e. with a thickness comprised between 0.5 mm and 1 mm, is linked precisely to its ability to be placed in vibration by low-power actuators.

[0089] For example, thin panes of this type are currently obtained by means of “endless strip” glass production processes, which allow widths in the order of 1500 mm and potentially unlimited lengths to be obtained; the mechanical resistance is usually increased by means of a chemical tempering process.

[0090] On the other hand, the first and second pane 2, 3 have a greater thickness to guarantee that the structure has mechanical resistance, particularly to the wind, impacts, human actions.

[0091] The third pane 4 must be easily excitable in a broad range of frequencies, comprised between 100 Hz and 6000 Hz. The choice of vibration frequencies is determined by the characteristics of the human voice, the sound frequencies of which range mainly from 100 Hz to 6000 Hz. Most of the sound that influences the intelligibility of speech is specifically within the frequency range comprised between 300 Hz and 3000 Hz.

[0092] Excitation of the third pane 4 is more efficient the more rigid is the fixing of the vibro-acoustic transducer 9 to the third pane 4.

[0093] Preferably, the vibro-acoustic transducer 9 is installed on the third pane 4 by means of gluing.

[0094] As an alternative, the vibro-acoustic transducer 9 is installed on the third pane 4 by means of magnetic coupling or by means of adhesive or withsuction cups.

[0095] The vibro-acoustic transducer 9 is applied to the third pane 4 in a position such as not to compromise the passage of light through it.

[0096] Preferably, the vibro-acoustic transducer 9 is applied in proximity to one of the edges 14a, 14b of the third pane 4. For example, the vibro-acoustic transducer 9 could be applied to an edge 14a of the third pane 4.

[0097] Preferably, the vibro-acoustic transducer 9 is applied to one of the planar surfaces 4a, 4b of the third pane 4.

[0098] In the embodiment illustrated in Figure 1 , the vibro-acoustic transducer 9 is applied to the outer planar surface 4a. As an alternative, the vibro-acoustic transducer 9 can be applied to the inner planar surface 4b.

[0099] Preferably, the vibro-acoustic transducer 9 is applied to a peripheral zone of the outer planar surface 4a (or of the inner planar surface 4b).

[0100] In this context, peripheral zone means an area of the planar surface 4a, 4b that is at a distance from one of the edges 14a, 14b of the third pane 4, preferably not greater than 15% of the length of the pane.

[0101] In accordance with one embodiment, illustrated in Figures 1 and 2, the system 1 comprises a plurality of vibro-acoustic transducers 9 which are applied in as many peripheral zones of one of the planar surfaces 4a, 4b of the third pane 4.

[0102] In particular, Figure 2 illustrates vibro-acoustic transducers 9 equally distanced apart and arranged so as to follow the entire outline of the third pane 4.

[0103] The choice of the number of vibro-acoustic transducers 9 and their specific positioning on the third pane 4 depends on the size of the module formed by the frame 7 and by the panes 2, 3, 4, which, in turn, is designed based on the dimensions of the protected environment 100 that it is intended to insulate.

[0104] In accordance with an aspect of the invention, the vibro-acoustic transducers 9 are loudspeakers of the magnetodynamic type, typically made of materials with exceptional magnetostrictive capabilities.In accordance with one embodiment, the vibro-acoustic transducers 9 comprise a permanent magnet made of Terfenol-D, which has excellent magnetostrictive capabilities. As an alternative, the permanent magnet is made of neodymium.

[0105] Magnetodynamic loudspeakers are known in the prior art, and therefore will not be further described.

[0106] The vibro-acoustic transducer is controlled by a dedicated control unit 10. In particular, the system 1 comprises a signal generator 20 coupled to the vibro-acoustic transducer 9 to send to the latter signals to be reproduced. In a basic application, the control unit 10 is configured to command the signal generator 20 to generate a predefined signal according to an open-looped control chain, illustrated in Figure 4.

[0107] For example, the predefined signal is white noise or pink noise, so as to mask the speech inside the protected environment 100.

[0108] In a simple application, for example, the vibro-acoustic transducer 9 is used to spread music or relaxing sounds, independently of the sound present in the protected environment 100.

[0109] In another application of the invention, the control unit 10 is configured to actuate an active control of the vibrations emitted by the vibro-acoustic transducer 9 based on the audio signals that are detected in the protected environment 100.

[0110] In this application of the system 1 , detection of the vibro-acoustic signal associated with the sound field present in the protected environment 100 can be actuated by using a receiver indicated as 8a. The type of the receiver 8a varies according to its mounting position. For example, as illustrated in Figure 1 , the receiver 8a can be mounted on the inner pane 2 so as to acquire the vibrations induced on the inner pane 2 by the sound field present in the protected environment 100. In this case, the receiver 8a will be formed by a vibro-acoustic transducer.

[0111] As an alternative, the receiver 8a can also be mounted on the outer side of the frame 7 facing the protected environment 100, in order to acquire thesound field present in the room. In this case, the receiver 8a will be formed by a vibro-acoustic transducer, a microphone.

[0112] In response to an audio signal detected by the receiver 8a, the control unit 10 is configured to command the signal generator 20 to generate a signal having a frequency and amplitude such as to mask the audio signal detected by the receiver 8a, as in Figure 4.

[0113] In another application, the system 1 comprises, in addition to the receiver 8a, a further vibro-acoustic transducer 8b applied to the third pane 4. The further vibro-acoustic transducer 8b has the task of checking the resulting signal present on the third pane 4.

[0114] In this application, the receiver 8a, the control unit 10, the signal generator 20, the vibro-acoustic transducer 9 and the further vibro-acoustic transducer 8b define a closed-loop control chain, as shown in Figure 5. In particular, the control unit 10 is configured to command the signal generator 20 to generate a signal that is continuously adapted based on the audio signal detected by the receiver 8a. In a further refinement of the application, an external control unit can be configured to recognise the acoustic fingerprint of the speakers present in the protected environment 100 and, in response to such recognition, provide information to the control unit 10 for the generation of customised masking signals based on the vocal characteristics of each speaker.

[0115] In practice, based on the level of security that it is intended to achieve, it is possible to design a control that is more or less sophisticated.

[0116] In the embodiment illustrated in Figure 1, the control unit 10 and the signal generator 20 are mounted solidly constrained to the frame 7, in particular on the outside of the frame 7.

[0117] In such embodiment illustrated, the receiver 8a, the further vibro-acoustic transducer 8b and the vibro-acoustic transducer 9 are connected by means of corresponding cables 18a, 18b and 19 to the control unit 10 and to the signal generator 20. As an alternative, it is possible to have a wireless connection.The control unit 10 and the signal generator 20 can also be housed in the frame 7.

[0118] The units described above refer to a system with three transparent panes and two gaps, but this module can be repeated, to obtain units with N transparent panes and N-1 gaps.

[0119] In particular, the system 1 can comprise one or more additional transparent panes mounted on the frame 7.

[0120] These additional transparent panes are interposed between the first pane 2 and the third pane 4 and / or between the third pane 4 and the second pane 3, so as to define further chambers. In practice, each chamber is delimited by a pair of panes.

[0121] Similar vibro-acoustic transducers to the one applied to the third pane 4 can be applied on the additional transparent panes.

[0122] In particular, such vibro-acoustic transducers are configured to emit a vibration signal at a frequency comprised between 100 Hz and 6000 Hz. Such vibro-acoustic transducers are also coupled to the signal generator 20 and to the control unit 10.

[0123] From the description given, the features of an acoustic insulation system according to the present invention appear clear, as do the advantages thereof.

[0124] In particular, the proposed system is capable of efficiently preventing or counteracting eavesdropping with laser microphones, safeguarding the confidentiality and privacy of a protected environment.

[0125] The invention effectively proposes an autonomous module capable of insulating spaces / rooms and preventing eavesdropping with laser microphones, maintaining the advantage of use of a transparent structure. The structure has excellent thermal and acoustic insulation capacities, thanks to the double insulating chamber, and is capable of masking the sound produced in a protected environment. Masking of the sound in the protected environment does, in fact, occur thanks to the vibro-acoustic transducers which opportunely excite the thin pane. This pane is made tovibrate according to a control adaptable to the degree of security required by the specific application.

[0126] It is, in fact, possible to go from a simple open-looped control chain (for example, generation of music or white / pink noise) to a more or less sophisticated feedback control, which adapts the vibration generated to the speech effectively detected in the protected environment.

[0127] The proposed system is easy to install in pre-existing environments and does not require the alteration or renovation thereof. Furthermore, it is a system with easy and rapid maintenance.

Claims

CLAIMS1. Acoustic insulation system (1) usable for acoustically insulating a protected environment (100) from an external environment (200), said system (1) comprising:- a first transparent pane (2) and a second transparent pane (3), said first pane (2) and said second pane (3) being distanced from and parallel to each other, said first pane (2) being positionable towards the protected environment (100) and said second pane (3) being positionable towards the external environment (200);- at least a third transparent pane (4) interposed between said first pane (2) and said second pane (3) so as to define a first chamber (5) delimited by the first pane (2) and by the third pane (4) and a second chamber (6) delimited by the second pane (3) and by the third pane (4), said third pane (4) having a lower thickness with respect to the first pane (2) and to the second pane (3);- a frame (7) on which said panes (2, 3, 4) are mounted;- at least one vibro-acoustic transducer (9) applied to the third pane (4) and configured to emit a vibration signal at a frequency comprised between 100 Hz and 6000 Hz;- a signal generator (20) coupled to said at least one electro-acoustic transducer (9) to send to the vibro-acoustic transducer (9) signals to be reproduced;- a control unit (10) configured to command the signal generator (20) to generate signals to be sent to the vibro-acoustic transducer (9);- a system of gaskets in soft material interposed between the frame (7) and said panes (2, 3, 4).

2. The system (1) according to claim 1, wherein said third pane (4) has a thickness comprised between 0.5 mm and 1 mm.

3. The system (1) according to claim 1 or 2, wherein said control unit (10)is configured to command the signal generator (20) to generate a predefined signal.

4. The system (1) according to any one of the preceding claims, wherein said control unit (10) is configured to command the signal generator (20) to generate a signal in response to the receipt of an audio signal relating to the protected environment (100).

5. The system (1) according to claim 4, further comprising a receiver (8a) mounted on the first pane (2) or on an outer side of the frame (7) facing the protected environment (100), said receiver (8a) being configured to detect audio signals, in response to the receipt of an audio signal from the receiver (8a), said control unit (10) being configured to command the signal generator (20) to generate a signal having frequency and amplitude such as to cancel or to mask the audio signal coming from the receiver (8a).

6. The system (1) according to claim 5, further comprising at least one further vibro-acoustic transducer (8b) applied to the third pane (4), said receiver (8a), said control unit (10), said signal generator (20), said vibro-acoustic transducer (9) and said further vibro-acoustic transducer (8b) defining a closed-loop control chain.

7. The system (1) according to any one of the preceding claims, wherein said at least one vibro-acoustic transducer (9) is of the magnetodynamic type.

8. The system (1) according to any one of the preceding claims, wherein said at least one vibro-acoustic transducer (9) is applied to a peripheral zone of the first pane (4), said peripheral zone being close to an edge (14a, 14b) of the third pane (4).

9. The system (1) according to any one of the preceding claims, wherein said at least one vibro-acoustic transducer (9) is installed on said third pane (4) by means of gluing, magnetic coupling or by means of adhesive or by means of one or more suction cups.

10. The system (1) according to any one of the preceding claims, comprising one or more additional transparent panes, said one or more additional transparent panes being interposed between the first pane (2) and the third pane (4) and / or between the third pane (4) and the second pane (3) so as to define further chambers, said one or more additional transparent panes being mounted on the frame (7).

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