Self-excited sound field type non-contact sensor sensing method and non-contact touch device

Abstract

The application discloses a sensing method of a self-excitation sound field type non-contact sensor and a non-contact touch control device, and relates to the technical field of sensors.The sensor comprises a vibrating body, a piezoelectric ceramic and a piezoelectric film arranged on the vibrating body.The sensing method comprises the following steps: the piezoelectric ceramic is driven to vibrate by an input excitation signal, and drives the vibrating body to generate bending vibration of the same frequency; the bending vibration of the vibrating body excites ultrasonic waves, and generates acoustic radiation force after being reflected by an obstacle within a set range; the piezoelectric film generates deformation under the influence of the acoustic radiation force, and outputs a voltage signal; and the amplitude of the voltage signal changes with the change of the amplitude of the bending vibration.Based on the acoustic radiation force of the ultrasonic sound field, the ultrasonic waves are continuously emitted to generate a sound field between the sensor and the obstacle, the non-contact sensing is realized by detecting the influence of the acoustic radiation force of the sound field on the vibration displacement of the sensor, and the non-contact human-computer interaction in a vehicle is further realized.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to a sensing method for a self-excited acoustic field type non-contact sensor and a non-contact touch device. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] In the field of vehicle electronics, human-machine interaction is currently mainly achieved through touchscreens. Touchscreens directly read target commands through physical contact between the user's hand and the screen, transmitting them to the control system to perform the corresponding operation. Although using touchscreens for sensing is simple, direct, and effective, it also has certain drawbacks.

[0004] First, physical contact between the hand and the screen causes wear and tear over time, affecting the screen's lifespan. Second, when there are contaminants, bacteria, or viruses on the hand or screen, direct contact can lead to contamination and the spread of these viruses. Finally, compared to earlier use of mechanical switches for human-computer interaction, both methods require physical contact between the hand and the target, resulting in no substantial change in the operation process and failing to further enhance the user's sense of interaction and novelty. Summary of the Invention

[0005] To address the aforementioned issues, this invention proposes a sensing method and a non-contact touch control device for a self-excited acoustic field non-contact sensor. Based on the ultrasonic acoustic field radiation force, it continuously emits ultrasonic waves to generate an acoustic field between the sensor and an obstruction. Non-contact sensing is achieved by detecting the influence of the acoustic field radiation force on the sensor's vibration displacement, thereby further realizing non-contact human-machine interaction inside the vehicle.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a sensing method for a self-excited acoustic field type non-contact sensor, the sensor comprising a vibrating body and a piezoelectric ceramic and a piezoelectric thin film disposed on the vibrating body; The sensing method includes: The piezoelectric ceramic vibrates when driven by the input excitation signal, and drives the vibrating body to produce bending vibrations at the same frequency. The bending vibration of the vibrator generates ultrasonic waves, which are reflected by an obstruction within a set range to produce acoustic radiation force. The piezoelectric film deforms under the influence of acoustic radiation force and outputs a voltage signal. The amplitude of the voltage signal changes with the amplitude of the bending vibration.

[0007] As an alternative implementation, the excitation signal is a sinusoidal signal, and the frequency of the excitation signal is the resonant frequency of the bending vibration of the vibrating body.

[0008] As an alternative implementation, the resonant frequency of the bending vibration of the vibrator is 17650Hz.

[0009] As an alternative implementation, the voltage of the input excitation signal is amplified to a set value and then input to the positive and negative poles of the piezoelectric ceramic, causing the piezoelectric ceramic to vibrate at a corresponding frequency, thereby driving the vibrating body to produce bending vibration at the same frequency.

[0010] As an alternative implementation, after the obstruction reflects the ultrasonic wave, a standing wave sound field is formed in the area between the sensor and the obstruction. The standing wave sound field generates an acoustic radiation force that acts on the sensor, thereby affecting the amplitude of the bending vibration.

[0011] As an alternative implementation, changing the distance between the obstruction and the sensor leads to a change in the intensity of the standing wave sound field, and the change in the standing wave intensity leads to a change in the sound radiation force.

[0012] As an alternative implementation, the process of determining the range includes: when the distance between the obstruction and the sensor gradually increases from zero, the amplitude of the piezoelectric film output voltage signal first increases, then decreases, and then increases again; the minimum point when the amplitude decreases is determined, and based on the voltage value corresponding to the minimum point, another point with the same voltage value is found in the first increasing interval, and the distance value corresponding to the other point is the end point of the range.

[0013] As an alternative implementation, the measuring range is 0-5.4 mm.

[0014] As an alternative implementation, both the piezoelectric ceramic and the piezoelectric film are bonded and fixed to the vibrating body, and support rods are added at the vibration mode node positions of the vibrating body.

[0015] In a second aspect, the present invention provides a non-contact touch device, including a device body and a self-excited sound field non-contact sensor disposed on the device body, and realizes non-contact sensing touch control through the sensing method of the first aspect.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention, based on the influence of ultrasonic sound field radiation force, designs a sensing method for a self-excited sound field non-contact sensor and a non-contact touch control device, which can be used to realize non-contact human-machine interaction inside vehicles. The sensor itself can generate high-frequency vibrations to excite ultrasonic waves. When there is an obstruction in the direction of ultrasonic wave propagation, a standing wave sound field is generated between the obstruction and the sensor. The sound radiation force of this standing wave sound field affects the amplitude of the sensor's bending vibration. Thus, non-contact sensing is achieved by detecting the influence of the sound field radiation force on the sensor's vibration displacement. In terms of service life, this self-excited sound field non-contact sensor can achieve sensing without physical contact, avoiding wear and tear from collisions and extending its service life. Regarding pollution propagation, the non-contact sensing method cuts off the propagation path of physical contact, reducing the risk of spreading pollutants, bacteria, and viruses. In terms of enhanced user experience, users can control the vehicle non-contactly, a significant change from traditional contact methods, enhancing interactivity and novelty.

[0017] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of a self-excited acoustic field non-contact sensor provided in Embodiment 1 of the present invention; wherein, 1, vibrating body; 2, piezoelectric ceramic; 3, piezoelectric thin film; Figure 2 The flowchart illustrates the sensing principle of the self-excited acoustic field non-contact sensor provided in Embodiment 1 of the present invention. Figure 3 This is a diagram showing the admittance characteristics of a vibrating body provided in Embodiment 1 of the present invention; Figure 4 This is a comparison diagram of the actual vibration modes and simulated vibration modes of the sensor provided in Embodiment 1 of the present invention; Figure 5 This is a graph showing the variation of the output voltage amplitude of the piezoelectric thin film with the spacing provided in Embodiment 1 of the present invention. Figure 6 This is an oscilloscope reading before the sensor is blocked, as provided in Embodiment 1 of the present invention. Figure 7 This is an oscilloscope reading result diagram when the sensor is obstructed, as provided in Embodiment 1 of the present invention; Figure 8 The image shows the oscilloscope readings after the sensor is blocked, as provided in Embodiment 1 of the present invention. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0022] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form as well. Furthermore, it should be understood that the terms “comprising” and “including”, and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0023] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0024] Sensors are key devices for realizing human-computer interaction. Currently, the automotive electronics field uses touchscreen sensors for human-computer interaction. This method relies on physical contact between the user's hand and the screen for sensing, which leads to wear and tear over time, affecting its lifespan. Furthermore, the need for hand contact means that if contaminants, bacteria, or viruses are present on the hand or screen, direct contact can cause contamination and spread of these pathogens. Compared to earlier methods using mechanical switches, both still require physical contact between the user and the target, offering no substantial change in the operation process and failing to enhance the user's sense of interaction and novelty.

[0025] To address the aforementioned issues, this invention designs a self-excited acoustic field non-contact sensor based on the influence of ultrasonic sound field radiation force, enabling non-contact human-machine interaction within vehicles. This sensor generates high-frequency vibrations to excite ultrasonic waves. When an obstruction exists in the direction of ultrasonic wave propagation, a standing wave acoustic field is generated between the obstruction and the sensor. The acoustic radiation force of this standing wave field affects the bending vibration amplitude of the sensor. Therefore, non-contact sensing is achieved by detecting the sensor's amplitude, overcoming the shortcomings of in-vehicle contact touchscreens and providing a novel approach for the development of subsequent non-contact sensors.

[0026] In terms of lifespan, this self-excited acoustic field non-contact sensor can achieve sensing without physical contact, and will not be worn due to collisions, thus extending its lifespan. In terms of pollution transmission, the non-contact sensing method cuts off the transmission path of physical contact, reducing the risk of spreading pollutants, bacteria, and viruses. In terms of enhancing the user experience, users can control the vehicle in a non-contact manner, which is a significant change from the traditional contact method and can enhance the sense of interaction and novelty.

[0027] Example 1 like Figure 1 As shown, this embodiment provides a self-excited acoustic field type non-contact sensor, including a vibrator 1 and a piezoelectric ceramic 2 and a piezoelectric thin film 3 disposed on the vibrator 1.

[0028] Both the piezoelectric ceramic 2 and the piezoelectric film 3 are bonded and fixed to the vibrator 1. The vibrator 1 is made of aluminum alloy, with the main body being a 20*5*0.5mm cube, and four 2*0.5*0.5mm support rods added at the vibration mode node positions.

[0029] Among them, the geometric dimensions of the piezoelectric ceramic 2 are 5*5*0.5mm, and the geometric dimensions of the piezoelectric film 3 are 8*5*0.028mm.

[0030] like Figure 2 The diagram shown illustrates the implementation principle of the self-excited acoustic field non-contact sensor described above, which includes the following: (1) The frequency of the excitation signal input to the piezoelectric ceramic 2 is set by the signal generator, and the voltage of the excitation signal is amplified to the set value by the operational amplifier and then input to the positive and negative poles of the piezoelectric ceramic 2, so that the piezoelectric ceramic 2 generates vibration at the corresponding frequency (i.e., the frequency of the signal generated by the signal generator), thereby driving the vibrator 1 to generate bending vibration at that frequency.

[0031] The setting value is the sum of the amplitude of the signal generator output signal and the operational amplifier amplification factor, and can be set to 100V.

[0032] The excitation signal is a sinusoidal signal, and the frequency of the excitation signal is the resonant frequency of the bending vibration of the vibrating body 1.

[0033] The resonant frequency is an experimentally measured value. The admittance data of the vibrating body 1 at different frequencies are measured using an impedance analyzer, such as... Figure 3 As shown, the peak frequency corresponding to the admittance-frequency curve is 17650Hz. This frequency is considered to be the optimal excitation frequency for the bending vibration of the vibrating body 1, i.e., the resonance frequency.

[0034] (2) The bending vibration of the vibrator 1 will emit ultrasonic waves. When there is an obstruction in the propagation path of the ultrasonic waves, the obstruction acts as a reflector of the ultrasonic waves to reflect the ultrasonic waves, thereby forming a standing wave sound field of a certain intensity in the area between the sensor and the obstruction. The standing wave sound field generates an acoustic radiation force acting on the sensor, thereby affecting the amplitude of the bending vibration.

[0035] (3) The change in the distance between the obstruction and the sensor will cause the intensity of the intermediate standing wave sound field to change, and the change in the sound field intensity will cause the sound radiation force acting on the sensor to change. Therefore, different distances will produce different sound radiation forces acting on the sensor, and different sound radiation forces will have different effects on the vibration displacement of the sensor.

[0036] Therefore, this embodiment uses acoustic radiation force as an intermediate quantity, and achieves non-contact measurement of the distance between the sensor and the obstruction by detecting the vibration displacement of the sensor at different distances.

[0037] To this end, a piezoelectric film 3 is introduced as a signal conversion medium. Under the influence of acoustic radiation force, the piezoelectric film 3 bends and vibrates along with the sensor, causing itself to deform and output a voltage signal. The amplitude of the voltage signal changes in real time with the change of the amplitude of the bending vibration (i.e., the magnitude of the vibration displacement).

[0038] (4) The voltage signal output by the piezoelectric film 3 is transmitted to a voltage signal reading device such as an oscilloscope, and non-contact sensing is achieved by reading the voltage signal output by the piezoelectric film 3.

[0039] Currently, non-contact sensors made using ultrasound, such as reversing radar, are mainly used in the far field. They achieve non-contact sensing by intermittently emitting ultrasound and using the time it takes for the ultrasound to travel to obtain distance information.

[0040] The non-contact sensing method proposed in this embodiment is mainly applied to the near field. By continuously emitting ultrasonic waves, a sound field is generated between the transmitter and the reflector. Non-contact sensing is achieved by detecting the effect of the sound field radiation force on the vibration displacement of the transmitter. It has strong real-time performance and fast response speed.

[0041] Figure 4 This is a comparison diagram of the actual vibration modes and simulated vibration modes of the sensor, where, Figure 4 (a) in the figure represents the actual vibration mode of the sensor vibrating body surface measured using a Doppler laser vibrometer. The vibration mode is bending vibration, and... Figure 4 The simulated vibration modes in (b) are basically consistent.

[0042] Figure 5The graph shows the variation of the piezoelectric film output voltage amplitude as a function of the distance between the obstruction and the sensor. It can be observed that as the distance between the obstruction and the sensor gradually increases from zero, the piezoelectric film output voltage amplitude first increases, then decreases, and then increases again. Therefore, within a specific range, a single voltage value corresponds to multiple distance values.

[0043] To ensure a one-to-one correspondence between the input spacing and the output voltage, the minimum point where the output voltage amplitude decreases is found. The corresponding minimum value is 5.05V, which is the maximum repeating amplitude of the deviation. Based on the voltage value at this point, another point with the same voltage value is found in the first voltage increase interval. The spacing value corresponding to this other point is the end point of the usable monotonic interval, which is also the end point of the range of this non-contact sensor.

[0044] Therefore, it can be seen that the effective range is the area of ​​0-5.4mm on the left side of the curve, which is the range of the self-excited acoustic field non-contact sensor.

[0045] This numerical range is primarily influenced by the amplitude and frequency of the vibrator 1. The effective range increases with the voltage setting and can be adjusted according to application requirements.

[0046] When the distance between the obstruction and the sensor is within the measurement range, the distance between the obstruction and the sensor can be obtained by reading the output voltage amplitude of the piezoelectric film 3, thus realizing non-contact distance measurement.

[0047] Figures 6-8 This is a diagram showing the results of a non-contact sensor test. A hand can be controlled to slide across the sensor, maintaining a vertical distance of approximately 1mm between the hand and the sensor. The sensor undergoes three phases of change: unobstructed, obstructed, and back to unobstructed. The voltage signal output by the oscilloscope is recorded. It can be seen that when the hand moves from the left side to above the sensor, the voltage amplitude decreases from 5.08V to 4.60V. After moving to the right side, the voltage returns to its original value, achieving non-contact sensing.

[0048] In further embodiments, a non-contact touch device is also provided, including a device body and a self-excited sound field non-contact sensor disposed on the device body, thereby realizing non-contact sensing and touch control through the above-described sensing method.

[0049] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A sensing method for a self-excited acoustic field type non-contact sensor, characterized in that, The sensor includes a vibrating body and a piezoelectric ceramic and a piezoelectric thin film disposed on the vibrating body; The sensing method includes: The piezoelectric ceramic vibrates when driven by the input excitation signal, and drives the vibrating body to produce bending vibrations at the same frequency. The bending vibration of the vibrator generates ultrasonic waves, which are reflected by an obstruction within a set range to produce acoustic radiation force. The piezoelectric film deforms under the influence of acoustic radiation force and outputs a voltage signal. The amplitude of the voltage signal changes with the amplitude of the bending vibration. After the obstruction reflects the ultrasonic wave, a standing wave sound field is formed in the area between the sensor and the obstruction. The standing wave sound field generates an acoustic radiation force that acts on the sensor, thereby affecting the amplitude of the bending vibration. The change in the distance between the obstruction and the sensor leads to a change in the intensity of the standing wave sound field, and the change in the standing wave intensity leads to a change in the sound radiation force. The process of determining the range includes: when the distance between the obstruction and the sensor gradually increases from zero, the amplitude of the piezoelectric film output voltage signal first increases, then decreases, and then increases again; when the amplitude decreases, the minimum point is determined; based on the voltage value corresponding to the minimum point, another point with the same voltage value is found in the first increasing interval; the distance value corresponding to the other point is the end point of the range.

2. The sensing method of a self-excited acoustic field type non-contact sensor as described in claim 1, characterized in that, The excitation signal is a sinusoidal signal, and the frequency of the excitation signal is the resonant frequency of the bending vibration of the vibrating body.

3. The sensing method of a self-excited acoustic field type non-contact sensor as described in claim 2, characterized in that, The resonant frequency of the bending vibration of the vibrator is 17650Hz.

4. The sensing method of a self-excited acoustic field type non-contact sensor as described in claim 1, characterized in that, After the voltage of the input excitation signal is amplified to a set value, it is input to the positive and negative poles of the piezoelectric ceramic, causing the piezoelectric ceramic to vibrate at a corresponding frequency, which in turn drives the vibrating body to produce bending vibration at the same frequency.

5. The sensing method of a self-excited acoustic field type non-contact sensor as described in claim 1, characterized in that, The measurement range is 0-5.4 mm.

6. The sensing method of a self-excited acoustic field non-contact sensor as described in claim 1, characterized in that, Both the piezoelectric ceramic and the piezoelectric film are bonded and fixed to the vibrating body, and support rods are added at the vibration mode node positions of the vibrating body.

7. A non-contact touch device, characterized in that, It includes a device body and a self-excited sound field non-contact sensor disposed on the device body. The self-excited sound field non-contact sensor realizes non-contact sensing and touch control through the sensing method described in any one of claims 1-6.

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