Ultrasonic anti-eavesdropping and display device

Abstract

The utility model discloses an ultrasonic anti-eavesdropping and display device, the anti-eavesdropping device comprises an ultrasonic generator and an ultrasonic transducer, the ultrasonic generator at least inputs an ultrasonic signal of one driving frequency to the ultrasonic transducer for emission, and the ultrasonic transducer adopts a transparent electrostatic ultrasonic transducer array. According to the utility model, the sound recording eavesdropping can be effectively shielded by directly sending an ultrasonic interference signal or an interference signal carried on an ultrasonic carrier signal by utilizing the inaudible property of ultrasonic waves and the inherent nonlinearity of an acoustic device and combining the acoustic parametric array theory; in addition, the ultrasonic anti-eavesdropping device can be combined with a display device, and the application field of the ultrasonic anti-eavesdropping device is expanded.

Description

Technical Field

[0001] The utility model relates to the field of anti-eavesdropping security, in particular to an ultrasonic anti-eavesdropping and display device. Background Art

[0002] Eavesdropping or recording refers to the use of certain technological means to obtain effective audio information such as conversations or other sounds in a covert manner. This may cause damage to the party being eavesdropped or recorded to a certain extent.

[0003] Currently, most manufacturers use electromagnetic interference technology to prevent eavesdropping and recording, but since electromagnetic interference can prevent other electronic devices from working properly, there are certain limitations in its use.

[0004] Because ultrasound cannot be heard by the human ear, it can be applied to counter eavesdropping and recording. Currently, there are devices that use ultrasound to prevent eavesdropping and recording. Commonly used ultrasonic anti-eavesdropping devices generally utilize piezoelectric ceramic ultrasonic transducers. By emitting high-power ultrasonic signals, they exploit the nonlinear characteristics of the eavesdropping device's amplifier, saturating it and preventing the recording of actual sound signals.

[0005] However, existing piezoelectric ceramic ultrasonic transducers are not transparent, so they cannot be effectively integrated with display devices (such as notebooks and monitors), which limits their scope of use. Utility Model Content

[0006] The purpose of the utility model is to provide an ultrasonic anti-eavesdropping and display device.

[0007] To achieve the above-mentioned object, on the one hand, the utility model proposes an ultrasonic anti-eavesdropping device, which comprises at least an ultrasonic generator and an ultrasonic transducer, wherein the ultrasonic generator inputs at least one ultrasonic signal of a driving frequency to the ultrasonic transducer, and the ultrasonic transducer emits an ultrasonic signal;

[0008] The ultrasonic transducer is a transparent electrostatic ultrasonic transducer array, which includes a base layer, multiple support structures, and a vibration layer that is in contact with the frame of the base layer. The support structure is arranged between the base layer and the vibration layer to form an air gap required for the vibration layer to vibrate up and down. The support structure separates the base layer and the vibration layer into a plurality of ultrasonic transducer units arranged in an array. The plurality of ultrasonic transducer units constitute the transparent electrostatic ultrasonic transducer array.

[0009] The base layer includes a base layer and a bottom electrode formed on the end surface of the base layer close to the vibration sound-generating layer. The vibration layer includes a signal generating layer and a top electrode formed on the end surface of the signal generating layer close to the base layer. The vibration layer vibrates up and down under the action of the AC signal input between the top electrode and the bottom electrode to emit the ultrasonic signal that interferes with the eavesdropping device.

[0010] In a preferred embodiment, the ultrasonic generator emits ultrasonic signals of multiple driving frequencies to the ultrasonic transducer, and the ultrasonic transducer is provided with multiple signal emission channels corresponding to the number of driving frequencies, and an ultrasonic signal of one driving frequency is input to a corresponding one of the signal emission channels.

[0011] In a preferred embodiment, the ultrasonic signal is directly an ultrasonic signal or an ultrasonic signal formed by modulating an interference signal in an audible frequency band with an ultrasonic carrier signal.

[0012] In a preferred embodiment, the driving frequency of the transparent electrostatic ultrasonic transducer array ranges from 20kHz to 80kHz, and the corresponding spacing between two adjacent support structures ranges from 0.5mm to 5mm. The larger the spacing, the higher the corresponding driving frequency.

[0013] In a preferred embodiment, the interference signal is a noise signal, and the modulated ultrasonic signal is expressed as:

[0014] m(t)=n(t)×(cos(2πft)+1);

[0015] Where n(t) represents the noise signal, f represents the resonant frequency of the ultrasonic transducer, cos(2πft) represents the ultrasonic carrier signal, and t represents time.

[0016] In a preferred embodiment, the difference between the maximum driving frequency and the minimum driving frequency among the plurality of driving frequencies is less than or equal to 500 Hz.

[0017] In a preferred embodiment, the signal generating layer uses at least a transparent PET film, PEN film, CPI film or UTG film; and / or the bottom electrode and the top electrode use at least a transparent ITO layer; and / or the height of the air gap is 1um to 20um; and / or the diameter of the support structure is less than or equal to 100um.

[0018] In a preferred embodiment, the transparent electrostatic ultrasonic transducer array further includes an insulating layer, which is disposed between the top electrode and the bottom electrode; and / or the insulating layer is made of a transparent dielectric material with a relative dielectric constant between 2.5 and 3.5.

[0019] In a preferred embodiment, the frequency band of the interference signal is 20 Hz to 10 kHz.

[0020] On the other hand, the present invention provides an ultrasonic anti-eavesdropping display device, comprising the ultrasonic anti-eavesdropping device described above, wherein the base layer is directly a display screen, or the ultrasonic anti-eavesdropping device is bonded to the display surface of the display screen.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The utility model adopts a transparent electrostatic ultrasonic transducer array to directly generate an ultrasonic signal of one or more frequencies for interference, or modulates the interference signal in the audible frequency band with an ultrasonic carrier signal to obtain an ultrasonic modulated signal and transmits it covertly in the air. The utility model utilizes the inaudibility of ultrasonic waves and the inherent nonlinearity of acoustic devices, and combines the acoustic parametric array theory to effectively shield recorded eavesdropping by directly transmitting ultrasonic interference signals or interference signals carried on ultrasonic carrier signals. In addition, the electrostatic ultrasonic transducer array of the utility model is transparent, so it can be combined with a display device, expanding the application field of ultrasonic anti-eavesdropping equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figures 1 to 3 They are respectively schematic diagrams of the principle blocks of three embodiments of the present utility model;

[0024] Figure 4 This is a schematic structural diagram of the ultrasonic transducer of the utility model;

[0025] Figure 5 This is a schematic diagram of the structure of the ultrasonic transducer of the utility model, which is divided into multiple signal transmission channels;

[0026] Figure 6 This is a schematic diagram of the combination of the ultrasonic transducer and the display screen of the utility model;

[0027] Figure 7 This is a schematic diagram of original audio in a specific embodiment;

[0028] Figure 8 Schematic diagram of audio recorded after being covered by ultrasound in a specific embodiment of the present invention.

[0029] The accompanying drawings are:

[0030] 1. Ultrasonic generator, 2. Transparent electrostatic ultrasonic transducer array, 21. Base layer, 211. Base layer, 212. Bottom electrode, 22. Support structure, 23. Vibration layer, 231. Signal generating layer, 232. Top electrode, 24. Air gap, 25. Insulation layer, 26. Signal transmission channel, 3. Display screen. DETAILED DESCRIPTION

[0031] The specific implementation methods of the present invention are described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific implementation methods.

[0032] Unless expressly stated otherwise, throughout the specification and claims, the term "comprise" or variations such as "include" or "comprising", etc., will be understood to include the stated elements or components but not to exclude other elements or other components.

[0033] like Figures 1 to 3 As shown, the ultrasonic anti-eavesdropping device disclosed in the present invention comprises at least an ultrasonic generator 1 and an ultrasonic transducer, wherein the ultrasonic generator 1 inputs at least one ultrasonic signal of a driving frequency to the ultrasonic transducer, which is then emitted by the ultrasonic transducer.

[0034] Specifically, during implementation, the ultrasonic generator 1 emits an ultrasonic signal at a single drive frequency or multiple drive frequency ultrasonic signals to the ultrasonic transducer, or emits a modulated ultrasonic signal. The modulated ultrasonic signal can be a signal formed by modulating an interference signal in the audible frequency band with an ultrasonic carrier signal. During implementation, the drive frequency and the ultrasonic carrier signal frequency are preferably in the range of 20kHz to 80kHz, with a frequency of approximately 25kHz being the most preferred frequency, as the high-frequency resonance peaks of most eavesdropping devices (such as MEMS microphones) are more saturated near this frequency.

[0035] In addition, when the ultrasonic generator 1 emits ultrasonic signals of multiple frequencies, the difference between the maximum and minimum drive frequencies among the multiple drive frequencies is preferably less than or equal to 500 Hz. This is because a parametric array is formed at this time, which will be demodulated in the air to produce audible sound, and the sound pressure level of the parametric array below 500 Hz is relatively low. For example, if the ultrasonic generator emits ultrasonic signals of six frequencies, they are preferably 24.8 kHz, 24.9 kHz, 25 kHz, 25.1 kHz, 25.2 kHz, and 25.3 kHz, respectively.

[0036] When the ultrasonic generator 1 emits a signal formed by modulating an interference signal in the audible frequency band with an ultrasonic carrier signal, the interference signal may be a noise signal, specifically a white noise signal, and its frequency band may be 20 Hz to 10 kHz. In a specific embodiment, the modulated ultrasonic signal may be expressed as:

[0037] m(t)=n(t)×(cos(2πft)+1);

[0038] Where n(t) represents the noise signal, f represents the resonant frequency of the ultrasonic transducer, cos(2πft) represents the ultrasonic carrier signal, and t represents time. Here, f is preferably in the same range as the drive frequency and the ultrasonic carrier signal frequency, and is most preferably around 25 kHz.

[0039] Preferably, in this embodiment, the ultrasonic transducer adopts a transparent electrostatic ultrasonic transducer array 2, such as Figure 4 As shown, it specifically includes a base layer 21, multiple support structures 22 and a vibration layer 23 that is in contact with the frame of the base layer 21. The support structure 22 is arranged between the base layer 21 and the vibration layer 23 to form an air gap 24 required for the vibration layer 23 to vibrate up and down, and the support structure 22 separates the base layer 21 and the vibration layer 23 into multiple ultrasonic transducer units arranged in an array. The multiple ultrasonic transducer units constitute the transparent electrostatic ultrasonic transducer array 2.

[0040] In this embodiment, the base layer 21 specifically includes a base layer 211 and a bottom electrode 212 formed on the end surface of the base layer 211 close to the vibration layer 23. The vibration layer 23 specifically includes a signal generating layer 231 and a top electrode 232 formed on the end surface of the signal generating layer 231 close to the base layer 21. During operation, an AC signal or a DC bias signal + AC signal is input between the top electrode 232 and the bottom electrode 212. Under the action of the input AC signal, the vibration layer 23 vibrates up and down to emit the above-mentioned ultrasonic signal that interferes with the eavesdropping device.

[0041] In addition, an insulating layer 25 is provided between the top electrode 232 and the bottom electrode 212 for insulating and isolating the top electrode 232 from the bottom electrode 212 .

[0042] During implementation, the signal generating layer 213 is made of a transparent material, such as a PET (polyethylene terephthalate) film, a PEN (polyethylene naphthalate) film, a CPI (polyimide) film or a UTG (ultra-thin flexible glass) film. The top electrode 232 and the bottom electrode 212 are made of a transparent electrode material, such as an ITO (indium tin oxide) layer. The insulating layer 25 is made of a transparent dielectric material, preferably a dielectric material with a relative dielectric constant between 2.5 and 3.5. The height of the air gap 24 formed between the base layer 21 and the vibration layer 23 is preferably 1um to 20um. The spacing between two adjacent support structures 22 is preferably in the range of 0.5mm to 5mm. The larger the spacing, the higher the corresponding driving frequency. By designing the spacing of different support structures 22, the driving frequency of the ultrasonic transducer can be adjusted so that the driving frequency is equal to the resonant frequency of the ultrasonic transducer. The support structure 22 is preferably a convex semicircular shape, and its diameter is preferably less than or equal to 100um to reduce the optical impact on the display device integrated therewith. The base layer 211 may be a transparent substrate, such as a glass substrate, or may be an existing display device, such as a display screen.

[0043] When the ultrasonic generator 1 sends ultrasonic signals of multiple driving frequencies to the transparent electrostatic ultrasonic transducer array 2, the transparent electrostatic ultrasonic transducer array 2 can be divided into multiple signal sending channels 26, and the driving frequency of each channel is different. For example, in the above example, the ultrasonic generator 1 sends ultrasonic signals of 6 driving frequencies, and the transparent electrostatic ultrasonic transducer array 2 is correspondingly divided into 6 signal sending channels 26, each signal sending channel 26 is driven by an ultrasonic signal of a driving frequency to send ultrasonic waves, such as Figure 5 shown.

[0044] Since the ultrasonic transducer of the present invention is transparent, it can be combined with an existing display screen. When combined, the base layer can be directly used as a display screen, or the ultrasonic transducer can be directly integrated with the display screen 3, such as laminating the base layer 211 of the ultrasonic transducer to the display surface of the display screen 3, such as Figure 6 shown.

[0045] The following is a specific embodiment to simulate and verify the anti-eavesdropping effect of the ultrasonic anti-eavesdropping device of the present invention.

[0046] In this embodiment, the ultrasonic generator 1 amplitude modulates a white noise signal n(t) with a frequency band of 20 Hz to 10 kHz onto an ultrasonic carrier signal cos(2π×25 kHz×t) to obtain a noise-modulated ultrasonic signal m(t)=n(t)×(cos(2π×25 kHz×t)+1).

[0047] The signal generating layer 231 of the transparent electrostatic ultrasonic transducer array 2 is made of PET film, the top electrode 232 and the bottom electrode 212 are made of ITO conductive layer, the height of the air gap 24 between the vibration layer 23 and the base layer 21 is 10um, the diameter of the support structure 22 is 100um, and the resonant frequency of the ultrasonic transducer is 25kHz.

[0048] The signal modulated by the ultrasonic generator 1 is input into the transparent electrostatic ultrasonic transducer array 2. The ultrasonic sound pressure level of the transparent electrostatic ultrasonic transducer array 2 at a distance of 2m is 120dB, and the effective anti-spying range is 2m and the angle is within 15°. For example, the original audio "one two three four five" is as follows: Figure 7 As shown, the audio recorded after being covered by ultrasound is as follows Figure 8 From the comparison, it can be seen that the ultrasonic anti-eavesdropping device of the present invention has a better anti-eavesdropping effect.

[0049] The advantages of the present invention are: the present invention adopts a transparent electrostatic ultrasonic transducer array to directly generate an ultrasonic signal of one or more frequencies for interference, or modulates the interference signal in the audible frequency band with an ultrasonic carrier signal to obtain an ultrasonic modulated signal and transmits it covertly in the air. The present invention utilizes the inaudibility of ultrasonic waves and the inherent nonlinearity of acoustic devices, and combines the acoustic parametric array theory to effectively shield recorded eavesdropping by directly transmitting ultrasonic interference signals or interference signals carried on ultrasonic carrier signals. In addition, the electrostatic ultrasonic transducer array of the present invention is transparent, so it can be combined with a display device, expanding the application field of ultrasonic anti-eavesdropping equipment.

[0050] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the present invention to the precise forms disclosed, and it is apparent that many modifications and variations are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the present invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the present invention and various options and variations. The scope of the present invention is intended to be defined by the claims and their equivalents.

Claims

1. An ultrasonic anti-eavesdropping device, characterized in that: The device comprises at least an ultrasonic generator and an ultrasonic transducer, wherein the ultrasonic generator inputs at least one ultrasonic signal of a driving frequency to the ultrasonic transducer, which is then emitted by the ultrasonic transducer; The ultrasonic transducer is a transparent electrostatic ultrasonic transducer array, which includes a base layer, multiple support structures, and a vibration layer that is in contact with the frame of the base layer. The support structure is arranged between the base layer and the vibration layer to form an air gap required for the vibration layer to vibrate up and down. The support structure separates the base layer and the vibration layer into a plurality of ultrasonic transducer units arranged in an array. The plurality of ultrasonic transducer units constitute the transparent electrostatic ultrasonic transducer array. The base layer includes a base layer and a bottom electrode formed on the end surface of the base layer close to the vibration sound-generating layer. The vibration layer includes a signal generating layer and a top electrode formed on the end surface of the signal generating layer close to the base layer. The vibration layer vibrates up and down under the action of the AC signal input between the top electrode and the bottom electrode to emit the ultrasonic signal that interferes with the eavesdropping device.

2. The ultrasonic anti-eavesdropping device according to claim 1, wherein: The ultrasonic generator emits ultrasonic signals of multiple driving frequencies to the ultrasonic transducer. The ultrasonic transducer is provided with multiple signal transmission channels corresponding to the number of driving frequencies. An ultrasonic signal of one driving frequency is input to a corresponding one of the signal transmission channels.

3. The ultrasonic anti-eavesdropping device according to claim 1, wherein: The ultrasonic signal is directly an ultrasonic wave or an ultrasonic signal formed by modulating an interference signal in an audible frequency band with an ultrasonic carrier signal.

4. The ultrasonic anti-eavesdropping device according to claim 1, wherein: The driving frequency of the transparent electrostatic ultrasonic transducer array is in the range of 20kHz to 80kHz, and the corresponding distance between two adjacent support structures is in the range of 0.5mm to 5mm. The larger the distance, the higher the corresponding driving frequency.

5. The ultrasonic anti-eavesdropping device according to claim 3, characterized in that: The interference signal is a noise signal, and the modulated ultrasonic signal is expressed as: m(t)=n(t)×(cos(2πft)+1); Where n(t) represents the noise signal, f represents the resonant frequency of the ultrasonic transducer, cos(2πft) represents the ultrasonic carrier signal, and t represents time.

6. The ultrasonic anti-eavesdropping device according to claim 2, characterized in that: A difference between a maximum driving frequency and a minimum driving frequency among the plurality of driving frequencies is less than or equal to 500 Hz.

7. The ultrasonic anti-eavesdropping device according to claim 1, characterized in that: The signal generating layer is made of at least a transparent PET film, PEN film, CPI film or UTG film; and / or the bottom electrode and the top electrode are made of at least a transparent indium tin oxide layer; and / or the height of the air gap is 1um to 20um; and / or the diameter of the support structure is less than or equal to 100um.

8. The ultrasonic anti-eavesdropping device according to claim 1, characterized in that: The transparent electrostatic ultrasonic transducer array further includes an insulating layer, which is arranged between the top electrode and the bottom electrode; and / or the insulating layer is made of a transparent dielectric material with a relative dielectric constant between 2.5 and 3.

5.

9. The ultrasonic anti-eavesdropping device according to claim 3, characterized in that: The frequency band of the interference signal is 20 Hz to 10 kHz.

10. An ultrasonic anti-eavesdropping display device, characterized in that: The display device comprises the ultrasonic anti-eavesdropping device according to any one of claims 1 to 9, the base layer is directly a display screen, or the ultrasonic anti-eavesdropping device is attached to a display surface of the display screen.

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