CN108052225B

CN108052225B - Interactive interface device for selectively exciting and receiving flat asymmetric sound waves

Info

Publication number: CN108052225B
Application number: CN201711379927.0A
Authority: CN
Inventors: 刘源
Original assignee: Nanjing Youchu Electronic Technology Co ltd
Current assignee: Nanjing Youchu Electronic Technology Co ltd
Priority date: 2014-02-28
Filing date: 2014-02-28
Publication date: 2020-12-15
Anticipated expiration: 2034-02-28
Also published as: CN107918508B; CN104881184A; CN108052224A; CN107967084B; CN107967084A; CN104881184B; CN107918508A; CN108052224B; CN108052225A

Abstract

The invention relates to an interactive interface device realized by selectively exciting and receiving a flat asymmetric sound wave, which comprises a flat plate with fixed size and at least one pair of acoustoelectric transducers. The touch position is deduced by the time difference of the elastic mechanical waves generated by clicking, namely the ultrasonic waves, reaching different sensor groups when the ultrasonic waves are transmitted in the flat plate. Piezoelectric transducers utilize flat plates to excite and receive sound waves for diaphragms, providing microphone and loudspeaker functions. The edge of the flat plate is provided with a slope surface which is symmetrical relative to the middle front surface, so that the signal of asymmetrical transmission ultrasonic waves generated by touch can be enhanced, and the symmetrical ultrasonic waves can be offset. The transducers are symmetrically adhered on the slope surface of the flat plate relative to the middle front surface and have opposite polarities, and symmetrical ultrasonic waves are further counteracted through bridging. The invention is suitable for making an interactive interface with a flat horizontal surface, and can be integrally assembled into the existing desktop or show window, for example: interactive show windows, interactive tables, interactive floors or intelligent bus stop products.

Description

Interactive interface device for selectively exciting and receiving flat asymmetric sound waves

The invention is a divisional application of an invention patent 'an interactive interface realized by selectively exciting and receiving a flat-panel asymmetric sound wave', application number 2014100696304, filed on 2014, 02, 28.

Technical Field

The invention relates to the field of human-computer interaction, in particular to a touch interface device for interaction between a user and a computer, and particularly relates to a novel facility for exciting and receiving ultrasonic waves in a panel, wherein the panel can be used for human-computer interaction and is provided with a microphone, a touch screen and a sound function.

Background

Touch means an input technique for allowing a computer user to control an image application through a touch sense. The touch technology can realize a more personalized man-machine interaction mode and can bring better application experience to users. The display carrier of the touch interface is usually an LCD or LED screen. Touch screens are typical applications in which a user transmits information to a machine through his or her finger, and the machine interprets and presents this information to the user through vision (a display screen). In this process, the user's finger is often in contact with the touch screen, and information is transferred to the machine by the position and movement of the finger on the touch screen. Things that can make a computer feel physically touching include: thermal, finger pressure, high speed cameras, infrared, optical sensing, resistance change, ultrasonic receivers, microphones, laser amplitude sensors, shadow sensors, etc. To use touch technology, conventional devices must be equipped with touch screens or touch pads, and software for recognizing finger touches must be loaded.

According to published data such as WO 9611378(a1), WO 0038104(a1), and WO 2004055661(a1), there is a touch technique of deriving (x, y) coordinate values by performing calculation based on ultrasonic waves generated in a panel upon clicking or colliding. Such techniques are generally applied to glass or metal materials, have four pairs of ultrasonic transducers, and generally optimize the mechanical mechanism of the interface to improve the signal-to-noise ratio, thereby collecting the signals generated when the sound waves generated by the click reach different transducers. Such techniques often have algorithms that can compute and derive positional information based on the time difference between the arrival of the vibration waves (ultrasonic waves) generated by the touch at different transducer groups. Such techniques may support the design and manufacture of interactive interfaces up to several square meters.

It should be mentioned that the ultrasonic waves mentioned here and in the present invention are mechanical elastic waves generated by touch and transmitted inside the solid body. Physically, the ultrasonic waves still belong to acoustic waves (acoustic waves).

However, the current inventions employing such techniques have several deficiencies. First, the larger the area of the interactive interface, the less accurate the touch screen employing such techniques, which is typically due to attenuation of the ultrasonic information as it passes through the solid in the flat panel. On the other hand, ultrasonic transducer's size, precision and anti-electromagnetic interference's ability, even the quality of electric wire access all can cause the influence to the precision of this type of technique to, in order to promote precision and accuracy, engineering design personnel often need arrange the protective housing outside the transducer or reduce the signal pollution that environmental factor brought through modes such as insulating coating. Thus, the traditional invention using such ultrasonic time difference of arrival techniques is not suitable for direct use by engineers in the furniture or construction industry. In fact, according to prior literature search, there has not been an interactive interface that maintains flatness after integration of the transducer, and that can be integrated directly into an existing work environment such as double glazing or a restaurant table as part of a window or desktop.

Finally, since the touch panel uses mechanical vibration ultrasonic waves transmitted in the panel to perform calculation, the acoustic-electric transducer used in the touch panel can be used as a microphone to record voice, or can be used as a sound box when a high voltage is applied, and the panel can be used as a diaphragm of the microphone or the loudspeaker at this time. However, when the human-computer interaction interface provides both microphone and sound functions, corresponding interference is generated. As is known, the sound function needs high-power output, and the ultrasonic transducer used by the corresponding invention can receive the vibration output by the sound function, the electric signal generated by the vibration is far greater than the strength of the signal generated by clicking, and the signal saturation is easily caused.

Disclosure of Invention

The technical problem to be solved by the present invention is to solve all the above problems and to provide a corresponding solution. The invention provides a structure which enables ultrasonic waves generated by clicking touch to pass through a special design, so that the ultrasonic waves can be transmitted according to a preset transmission route when being transmitted in a flat plate, and the precision and the accuracy of touch detection are improved.

Therefore, the invention designs a planar human-computer interaction panel which is processed by a special method, thereby improving the touch control precision and optimizing the signal quality when providing the microphone and sound functions. The invention also provides a high-fidelity scheme for playing sound by using the vibration of the flat plate.

In order to achieve these objects, the invention proposes, firstly, an ultrasound excitation-reception device comprising a rigid plate which can vibrate freely and to which several piezoceramic transducers are connected. The thickness of the plate, the processing of its edges and the natural frequency of vibration of the plate are all the core parameters of the invention. In fact, when the pad is used to detect the location of a click touch, we detect asymmetric ultrasonic waves generated by the click, which can be generated by various objects such as a finger, a pen, a hard plastic case, a key, a ring, etc., according to the algorithm of signal processing. To achieve good accuracy, we are mainly concerned with the portion of the multi-frequency vibration wave generated at the time of clicking, which is a high frequency, particularly, 80kHz to 100 kHz. According to the experimental result, when the object which clicks the flat plate is larger and softer, the ultrasonic frequency spectrum generated by touch is approximately biased to a low frequency, and the detection precision is lower.

The typical wavelength of the mechanical elastic vibration wave or the so-called ultrasonic wave according to the present invention is 40mm, and the material of the flat plate is glass or duralumin. The size of the piezoelectric ceramic transducer to which the present invention relates needs to be less than half the wavelength. When the flat plate is made of glass, the thickness of the flat plate is between 0.5mm and 20mm, and the side length of the flat plate is 6.8 meters at most. Under this arrangement condition, the mechanical elastic wave generated by the click touch is Lamb type ultrasonic wave. Such ultrasonic waves are characterized in that only two vibration wave transmission modes exist in the frequency range considered by us, one is symmetrical, and the other is asymmetrical. When the flat plate is made of glass or metal, the amplitude of the ultrasonic wave in the asymmetric transmission mode is far higher than that of the ultrasonic wave in the symmetric transmission mode. Therefore, detection is performed on the asymmetrical transmission ultrasonic wave, and the method is more advantageous when the click touch strength is slight. However, the problem is that asymmetric delivery is slower than symmetric delivery, and in typical glass plate applications the asymmetric ultrasonic delivery is 3300 meters per second, while the symmetric delivery is 5400 meters per second.

Considering that we do not know the size and the way of the click touch in advance, we need to select one of the two ways of transmission in advance for monitoring. Another feature of Lamb-type ultrasound is that its transmission mode can be selected based on boundary conditions. Lamb-type ultrasonic waves are transmitted as a set of a mechanical elastic transverse wave and a mechanical elastic longitudinal wave inside a flat plate. It can be observed that in the asymmetric mode of transmission, the shear waves are asymmetrically distributed with respect to the slab mid-plane, while the longitudinal waves are symmetrically distributed, and in the symmetric mode of transmission, the opposite is true, with the longitudinal waves being asymmetrically distributed. This characteristic can be exploited to define and screen different modes of delivery when monitoring. Two pairs of acoustoelectric transducers with the same size and completely consistent specifications are symmetrically adhered to the upper surface and the lower surface of a flat plate respectively, and the ultrasonic signal intensity in an asymmetric mode or a symmetric mode can be selected according to superposition or subtraction of electric signals when ultrasonic waves are excited or detected. Typically, the transducer signals of a pair of two transducers are overlapped, that is, the ultrasonic signals in the symmetric mode are eliminated through structural design while the ultrasonic signals in the asymmetric mode are enhanced.

Similar to the structure design, the transducer pair can be symmetrically attached to the upper surface and the lower surface of the inverted leg of the flat plate, and can also be used on the side edge of the flat plate. And the requirement on the machining precision is higher, the edge of the flat plate is usually polished, and the installation precision of the transducer is higher due to the small size.

Under the above configuration, we can use four sets of transducers to detect the click position. Each group of transducers is provided with a group of acoustoelectric transducers which are opposite to each other in pairs and respectively occupy four geometrical vertexes of the flat plate. The geometry of the plate can be square or rectangular. The detection position is calculated by observing the time difference between the arrival of the ultrasonic waves at different vertices caused by the touch. Meanwhile, the flat plate also has the antenna property of sound wave signals, and the facility related to the invention can realize the function of a microphone by utilizing four groups of transducers in a mode of detecting vibration signals transmitted into the flat plate by the sound wave signals under an asymmetric mode. Thus, the electrical signal generated by the ultrasound waves detected by the transducer in the asymmetric mode requires two steps of processing. Firstly, signals collected by the transducer are subjected to programmed amplification, and secondly, bandpass filtering is carried out according to different functional requirements. Filtering in the vicinity of 100kHz for position detection, i.e. touch functionality, and filtering of the analog microphone signal in the range of 0-4kHz for recording functionality, respectively. Each group of transducers can independently provide a group of recording signals, and the signals provided by the transducers in different groups have phase difference in consideration of different time for the ultrasonic signals to reach different transducer groups. We need to calculate the phase difference by discretization and recombination of the signals, from which on the other hand also the position information of a sound source in space can be obtained.

An important process flow in the interactive interface related by the invention is a processing mode of the edge of the flat plate. In fact, when the panel is touched by a click, the ultrasonic waves of different transmission modes are generated simultaneously and transmitted at different speeds within the panel and reflected when touching the edge of the panel. According to the quality of the edge surface, corresponding transformation can be generated between the two modes, namely, the ultrasonic wave transmitted by the partially asymmetric mode can be converted into the ultrasonic wave transmitted by the symmetric mode after the edge is reflected, and vice versa. Such a transformation is more or less disturbing for measuring the position of the touch point. In general, similar problems occur when the edge is damaged or processed. The edges of the flat plate interface are required to be kept flat or rounded.

The plate of the invention is characterized in that the edge of the plate is processed with slopes with symmetrical structures on both sides. For example, a glass plate with a thickness of 10mm is subjected to gradient processing, and the thickness of the glass plate gradually linearly decreases from 10mm to 5mm within a length of 30mm to the plate boundary. In the case of the slow gradient-change processing, the occurrence of transmission mode conversion due to reflection of the generated ultrasonic wave when it reaches the edge can be reduced. Yet another advantage is that the amplitude of the vibration waves at the edges is further enhanced due to the reduced thickness of the plate edges, and thus the electrical signals obtained by the transducer groups at the edges are enhanced. Selecting a 30mm grade machined length allows transducers of the general size of 20mm diameter 0.5mm thickness to be placed entirely on the grade and partially reduces the overall size of the interactive flat panel to which the invention relates. Meanwhile, the space left after gradient processing can be used for placing a power supply wire or an insulating glue coating and the like, so that the surface of the flat plate is integrally maintained to be horizontal. On the other hand, a protective shell can be made of materials such as brass on the slope surface. The shell has the functions of isolating the transducer group, the electric wire and other facilities from the outside and integrating the interactive flat panel into a complete plane facility. Therefore, the interactive flat plate can be used as a common flat plate and can be conveniently placed in the existing double-layer glass or other facilities needing to add interactive functions, such as a bar counter and the like. And the interference of environmental electromagnetic signals to the transducer group can be reduced by selecting metal materials such as brass and the like.

In order to realize the sound function of sound playing, the invention adds a fifth group of transducers (and adds a sixth group of transducers when the stereo function is performed) besides four groups of transducers. In order to optimize the sound playing quality and reduce the resonance feeling, the flat plate facility is covered with an absorption material at the edge slope part. When the playing function is realized, the audio signal is played to the ambient air by the flat panel. When the audio signal is loaded on the opposite transducers of the fifth group of transducers, a phase difference is added, so that the transmission of an asymmetric mode is realized, and in order to increase the signal transmission effect, a base carrier signal is added to the audio signal for modulation. The frequency f of the sound signal is typically between tens of hertz and twenty kilohertz, and the frequency of the modulation signal f0 selected by the present invention is typically between 40kHz and 4MHz, selected according to the size of the panel and the sound function requirements. The smaller the plate size, the higher the f0 frequency. The use of the f0 signal has the advantage that similar ultrasonic waves are transmitted in a flat plate with a certain frequency shift, and the influence of the frequency shift on the sound signal can be reduced by filtering after modulation. Of course, the modulation signal f0 needs to be a high frequency signal that the human ear cannot receive when transmitted by the plate vibration into the ambient air. The interactive facility meets the following conditions:

(1) when the sound playing function is realized, the ultrasonic waves generated by the transducer group are transmitted in the flat plate through the piezoelectric effect.

(2) The transmission effect of the flat plate is better than that of the flat plate in the symmetric mode when the flat plate vibrates in the asymmetric mode, and the flat plate needs to be realized by adding a phase difference between signals received by two transducers in a transducer group.

(3) The wavelength of the ultrasonic wave is more than half of the thickness of the flat plate.

(4) The ultrasonic vibrations in the plate are still linear, while the vibrations in the plate are non-linear in their transmission into the air, and it is observed that the transmission efficiency depends mainly on the sound frequency, i.e. f. This non-linear characteristic requires that we must use a modulated signal f0 to keep the audio signal f to be played consistent (otherwise loud or loud sounds will appear during playback).

Meanwhile, the selection of the modulation signal f0 can enable the signal generated by the sound playing function to generate a distance with the frequency spectrum of the voice signal recorded by the recording function, thereby avoiding mutual influence.

The present invention also has features including, but not limited to:

the acoustoelectric transducer used is a disk of piezoelectric ceramic with a silver coating attached to its surface. The resonant frequency of the piezoelectric ceramic is in the order of 100 kHz. The piezoceramic wafer is typically connected to the circuitry by a 1.8mm twin wire. The overall size is about 20mm in diameter and 2mm in thickness.

The acoustoelectric transducer is a piezoelectric ceramic disc, both sides of which are covered with a silver coating. The transducers are grouped in pairs, and the position of each group on the flat plate is symmetrical relative to the middle plane, namely the half-thickness plane, of the flat plate. The surface of the piezoelectric ceramic disk, which is not in contact with the flat plate, is connected with the double-strand electric wire in a welding way and protected by the metal shell to form a hood structure to form a Faraday cage. The interior of the hood is filled with resin so that it can be simply and precisely arranged on the flat plate.

The interactive plate is made of glass and has a rectangular shape. The thickness is between 6 and 20 mm. The edges of the flat plate are symmetrically processed in a slope mode. The angle of the slope is 0.1, namely, the whole thickness is reduced by 6mm on the slope length of 30 mm. The transducer groups are opposite to each other in pairs and are arranged in the middle of the corners of the flat plate in four groups. Each group of transducers consists of two piezoelectric ceramics, and the positions of the transducers are symmetrical relative to the central plane of the flat plate. The surface of the piezoelectric ceramic, which is in contact with the flat plate, is a vibration receiving surface, and the other surface is usually a ground surface. The weak electric signal generated when the vibration signal generated by the ultrasonic wave passes through the transducer is transmitted to the signal processing module through the twin wire with high signal-to-noise ratio. The four sets of transducers occupy the four vertices of the plate and determine the dimensions X and Y of the interaction area. The position information (xr, yr) of the click touch is calculated from the time difference between the mechanical elastic waves, i.e., ultrasonic waves, generated by the touch and transmitted to different transducer groups inside the panel. The fifth group of transducers are also placed on the slope surface and used for playing sound.

The flat plate can be made of multiple layers of glass, namely more than two layers of glass are bonded and combined through a polymer coating such as polyethylene.

The transducer for sound reproduction consists of two piezoelectric ceramics, the vibration signals of which have a phase difference of 90 degrees in the operating state.

The transducers for realizing the sound playing function are composed of two rectangular piezoelectric ceramics, and the two transducers are arranged on the slope surface of the edge of the flat plate in a symmetrical structure in pairs.

The transducer for realizing the sound playing function is composed of two annular piezoelectric ceramics, and the two annular piezoelectric ceramics are arranged on the slope surface of the edge of the flat plate in a symmetrical structure in pairs.

The played audio signals are played in groups of 10ms to 100ms, and the intervals between the groups can be used for acquiring other interactive signals such as voice.

Drawings

FIG. 1A is one of the acoustoelectric transducers according to the present invention, namely a disk-shaped piezoelectric ceramic plate having a double-sided silver electrode and welded with a twin wire, protected by a metal hood;

FIG. 1B is a cross-sectional view of FIG. 1A;

FIG. 2A is a schematic structural diagram of an interactive interface according to the present invention; the interface consists of a flat plate and five groups of piezoelectric ceramics and has a rectangular structure;

FIG. 2B is a partial cross-sectional view of the flat plate depicted in FIG. 2A, the flat plate having a dome machined with respect to a mid-elevation, i.e., half-thickness, plane, with the electro-acoustic sensors all mounted symmetrically on the dome with respect to the mid-elevation;

FIG. 2C is a schematic view of the slope forming space of FIG. 2B filled with a shock absorbing material, the filled space forming a horizontal surface with the interactive flat plate;

fig. 3 is a schematic cross-sectional view of an interactive interface according to the present invention in combination with a metal housing through which the interactive interface constructed by the present invention can be assembled as a whole into a corresponding product.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

Referring to fig. 1A and 1B, the present invention performs positioning by detecting elastic vibration waves, i.e., ultrasonic waves, generated by clicking touch, and requires the use of an acoustoelectric transducer, which is typically a disk-shaped piezoelectric ceramic plate having upper and lower silver coatings, i.e.,

electrodes

101 and 102. 101 and 102 can be soldered at the same level of the piezoelectric ceramics by the process of silver back plating and silver plating of the protective tape 109. The piezoelectric ceramic has a polarity, denoted by P or +. Using a thin twin wire 105, the outer strand cable 106 is connected to the electrode 102 by welding and the inner strand cable 108 is connected to the electrode 101 by welding after the insulation is stripped off. The metal hood 103 covers and protects the piezoelectric ceramics and the solder joint. The inner surface of the hood is coated with insulating glue 104 to ensure that short circuit does not occur with the electrode 101; meanwhile, the caps are connected to the 106 and 102 electrodes through the welding points 111. In this case, the metal hood 103 forms a faraday cage together with the electrode 102. The space 112 inside the metal hood 103 is filled with transparent or colored epoxy resin, thereby constructing a freely movable complete assembly with certain mechanical properties. The hood is made by stamping and leaves an opening 110 for the exit of the twinax cable. An insulating coating 107 covers the inner strands 108 of the twin wire up to the piezoceramic electrodes 101, ensuring that they do not short circuit the electrodes 102. The hood structure thickness is determined by the diameter of the twinax cable and generally does not exceed 2 mm. A typical thickness of the piezoceramic wafer is 0.5mm and a typical diameter is 20 mm.

Referring to fig. 2A, the edge of an interactive flat plate is processed to be sloped, and four piezoelectric transducer groups, which are respectively numbered N1, B2, R3, and J4, are attached to the edge of the interactive flat plate by adhesion. Each group of inner transducers is marked A or B according to the upper and lower surfaces of the flat plate on which the inner transducers are positioned. The four sets of transducers are oriented to form four vertices of the interaction area and to form a rectangular interaction area. In the area, the time t1, t2, t3 and t4 of the vibration wave of the click touch occurring at (xr, yr) reaching different transducer groups are recorded and sent to the processing chip MC, and the position information (xr, yr) can be obtained through geometric calculation. It should be noted that the ultrasonic wave mentioned in the present invention is a mechanical elastic wave generated by touch, and the vibration wave is transmitted inside the solid, and the ultrasonic wave is still a kind of acoustic wave (acoustic waves). The ultrasonic wave transmission speed is determined mainly by the frequency of the vibration wave, which is the material of the flat plate, and is a constant value, and is 3300m/s according to the technical manual when the vibration wave to be detected after filtering is 100kHz, for example, when the flat plate is made of glass. The slope surface processing does not influence the ultrasonic wave transmission speed. I.e., t1, t2, t3, t4, are determined solely by the distance of the touch point from the geometric center of the transducer. The position information can be derived theoretically according to the three distance information, and the four groups of transducers are used for increasing one group of margin and maintaining the geometric symmetry of the flat plate so as to maintain the uniformity of the detection precision. The overall size of the interactive interface is not the size of the flat panel, but the size of the flat panel is marked as (X, Y), and the center 0 is the center position of the rectangle.

The four groups of transducers can simultaneously carry out summary detection on the environmental voice information received by the flat plate through the piezoelectric effect. The fifth group of piezoelectric ceramics is marked as H1A and H1B, is also pasted on the flat plate, has rectangular or circular size and size larger than the first four groups of piezoelectric ceramics, converts the audio signal into vibration wave by the reverse effect of the piezoelectric effect, and transmits the signal to the ambient air by the flat plate as a diaphragm so as to realize the functions of sound or loudspeaker.

The five groups of transducers attached to the interactive interface are all connected to the signal processing module MC by cables. The MC internally comprises a signal filtering and amplifying circuit. For the first four groups of transducers, the peak value of the ultrasonic signal generated when the transducer is touched by clicking is generally about 100kHz, and MC is about 100kHz, so as to obtain the time difference of arrival of the ultrasonic wave. Meanwhile, the MC processing module provides filtering in a low frequency band, so that the ambient voice signals detected by the four groups of transducers simultaneously are gathered and averaged, and a microphone function is realized.

For the fifth group of transducers, the MC processing module has a signal amplifying circuit, and the audio signal to be played is played through the transducer H1. The playing time is selected to be segmented, and the interval is 10ms to 100ms, which is to prevent the signal generated by the H1 playing from generating signal saturation effect on the rest of the transducer groups. When the audio signal is loaded on the opposite transducers of the fifth group of transducers, a phase difference is added, so that the transmission of an asymmetric mode is realized, and in order to increase the signal transmission effect, a base carrier signal is added to the audio signal for modulation. The frequency f of the sound signal is typically between tens of hertz and twenty kilohertz, and the frequency of the modulation signal f0 selected by the present invention is typically between 40kHz and 4MHz, selected according to the size of the panel and the sound function requirements. The smaller the plate size, the higher the f0 frequency. The use of the f0 signal has the advantage that similar ultrasonic waves are transmitted in a flat plate with a certain frequency shift, and the influence of the frequency shift on the sound signal can be reduced by filtering after modulation.

The processing module MC is itself connected by a data line to a computer or other more powerful computing module 206. At 206 may be a computer PC having software for deriving and calculating (xr, yr) position according to the arrival time difference of the ultrasonic wave and projecting it onto a virtual space or a computer screen, so as to realize the one-to-one correspondence relationship between the size (X, Y) of the interactive interface and the pixel size of the computer screen. Particularly, when the flat panel is made of glass or other transparent or translucent materials, and the computer 206 projects the screen on the interactive surface through the projector, the detection of the click touch can be used as a corresponding input tool, for example, one touch is simulated as a left click of the mouse, and two touches within a short time are simulated as a right click of the mouse. Particularly, the interactive surface (X, Y) may be larger than the area of the projection display, and when a click outside the projection area is detected, the click may be used as a specific button to input functions, such as waking up the keyboard, starting recording, starting audio playing, etc.

Referring to fig. 2B, a set of acoustoelectric transducers N1A and N1B, fabricated by the method of fig. 1, have opposite polarities P, or N1A is + and N1B is-polar. The group of transducers are bonded on the flat plate 200 through glue, the flat plate 200 is processed into sloping surfaces, and the upper and lower sloping surfaces are geometrically symmetrical relative to the middle surface of the flat plate, namely a half-thickness surface 201. The slope is determined by the angle a, the depth b, and the length L. The chamfer machining is characterized by being smoother than the common chamfer machining, the chamfer angle a is generally 0.1rad, and the chamfer length L is generally 30mm to 40mm, so that enough space 203 is formed for arranging the transducer groups N1A and N1B, and the height of the space is ensured not to exceed the upper surface of the flat plate. The plate edges maintain vertical edges, or are rounded. The flat plate is made of glass, plastic or metal. Transducer groups N1A and N1B are bridged by a cable. According to the physical characteristics of Lamb type ultrasonic waves transmitted in the flat plate, the slow slope surface has the functions of enhancing asymmetric mode sound waves and attenuating symmetric mode sound waves. After the arrangement, the transducer group can further make the detected ultrasonic waves be the parts transmitted by asymmetric modes in two vibration transmission modes generated in the process of clicking touch through bridging, and the parts of the symmetric modes are cancelled out due to the fact that the polarities of the transducer group are opposite. Further, it is characterized in that when a mechanical elastic wave, i.e., an ultrasonic wave, is transmitted through a slope of a flat plate, the ultrasonic wave transmitted symmetrically is emitted toward the inside of the flat plate like a transverse wave when entering the slope, so that it is difficult to enter the transducer group, while an asymmetrical acoustic wave is emitted like a longitudinal wave, and is not emitted at the slope of the flat plate, and its vibration is amplified at the apex of the slope of the flat plate, so that a sufficient signal can be detected by the transducer group for position derivation even in a slight touch. In a special case where the piezoelectric ceramic is adhered to the outer edge of the slope, and the characteristic dimension, i.e., the diameter d of the disk-shaped ceramic is much smaller than the length L of the slope, and the depth b of the slope is less than or equal to half of the thickness e of the flat plate, sufficient information can be detected by using only 1 of N1A and N1B without using both them. This is because most of the symmetrically transmitted ultrasonic waves are completely attenuated after reflection by the inner edge of the slope.

Referring to fig. 2C, after the plate 200 is bonded to the piezoelectric ceramic transducer array shown in fig. 1, the space 203 left by the plate after the slope processing is filled with a resin material 204, and the surface of the plate is maintained to be a horizontal plane after the filling. The resin material is transparent or colored, and is a vibration wave absorbing material having a characteristic of absorbing ultrasonic vibration. The filling resin material may partially affect the detection of the vibration wave. Meanwhile, as the slope surface is processed, the resin thickness at the edge of the flat plate is the largest, the absorption function of the resin is strongest, and the echo effect generated by reflection after the vibration wave reaches the edge can be greatly reduced. Through adjustment and experimental configuration, the accuracy of the time difference calculation algorithm can be increased under the condition of not generating great influence on the detection of the ultrasonic signals by appropriate filling of the resin material. A typical configuration is one in which the ultrasonic signal amplitude attenuation before and after filling does not exceed 10%. By echo effect, it is meant that when the click touch location (xr, yr) is near the apex of the plate, the ultrasound it generates by reflection at the plate edge will reach a certain set of transducers earlier than the original ultrasound, resulting in a calculation failure. Cross-checking can generally be performed by increasing the amount of redundancy, i.e., using more than three sets of sensors, e.g., four sets of transducers as used in the present invention. The echo effect is eliminated by filling with a resin material, and then the algorithm of data processing is further simplified.

Referring to fig. 3, a rectangular plate 300 is processed through a slope surface in a manner shown in fig. 2B, and is bonded with a piezoelectric ceramic transducer group, and then is protected by a metal shell 301, the metal shell is made of stainless steel or brass, and is processed by sheet metal, and the edge of the metal shell is polished to be flat, so that the upper surface of the interactive plate can be adjusted to be horizontal by the metal shell. The flat plate 300 is separated from the metal shell 301 by an L-shaped fitting 302, which may be made of plastic or rubber, and the horizontal surface of the fitting is bonded to the inner surface of the metal shell, and the vertical surface is bonded to the vertical surface of the edge of the flat plate. The tightness between the plate and the metal housing is ensured by an insulating paste 303. The design enables the surface of the whole flat plate to be horizontal, so that the flat plate can be installed and assembled on nested structures 304 of products such as any required table tops, grounds, exhibition stands and the like in larger sizes in a mode similar to a common glass flat plate, the problem of assembly caused by edge areas generated after slope processing is avoided, and functional blocks of the flat plate, namely a piezoelectric ceramic group, are further distinguished from the external environment.

A typical application of the present invention is to arrange a flat panel equipped with a metal casing as a whole in the middle of a building such as a window, a floor, or a table, to realize human-computer interaction by using a pointing function of touching a click position and a microphone recording function as input facilities, by using a speaker or an audio function as output equipment, or by using a projector as output equipment. A typical plate used in the present invention is a plate having a thickness of 10mm, made of glass, and having an area of 1 square meter. The flat board under this thickness can support completely and stand alone on the flat board, through the hard objects such as detection heel with dull and stereotyped touching, realize a man-machine interaction ground, detect or monitor the position of people in the building.

To sum up, the present invention is suitable for making an interactive interface with a flat horizontal surface, which can be integrally assembled into a desktop or a shop window, for example: the interactive display system comprises various interactive products such as an interactive display show window, an interactive table, an interactive floor, an intelligent bus station, a billboard and a public display board. The method can improve the sensitivity of the touch control facility for detecting the position of the touch point by utilizing the ultrasonic arrival time difference technology. The panel manufactured by the invention realizes the detection of the click touch position, and simultaneously specially designs the interactive panel and a signal processing mode according to the characteristics of different sound wave signals of a microphone, a loudspeaker and touch detection, so that three functions can be finished by utilizing piezoelectric effect and reverse piezoelectric effect respectively in different frequency intervals by utilizing an acoustoelectric transducer, thereby simplifying the design and signal processing of a corresponding multimedia interactive interface, reducing the product cost and improving the human-computer interaction experience.

The present invention has been described in detail in order to enable those skilled in the art to understand the invention and to practice it, and it is not intended to limit the scope of the invention, and all equivalent changes and modifications made according to the spirit of the present invention should be covered by the present invention.

Claims

1. An interactive interface device for selectively exciting and receiving a flat asymmetric acoustic wave, the interactive interface device comprising a flat plate of a certain size and at least one set of acoustoelectric transducers; the method is characterized in that: the flat plate at least has a local geometric area which can generate an attenuation effect on the symmetrically transmitted ultrasonic waves, so that the acoustic-electric transducer is ensured to mainly detect the ultrasonic waves transmitted in an asymmetric mode generated by excitation when clicking and touching; the surface of the flat plate in the local area is not a horizontal plane but a symmetrical slope surface with a certain angle relative to the half height surface of the flat plate; meanwhile, the acoustic-electric transducers are opposite pairwise and are symmetrically arranged on the flat plate relative to the half-height surface; the acoustoelectric transducer is a piezoelectric ceramic disc, and silver coating electrodes are covered on two surfaces of the acoustoelectric transducer; the acoustoelectric transducers are grouped in pairs and have opposite polarities, and the position of each group on the flat plate is symmetrical relative to the middle plane, namely the half-thickness plane, of the flat plate; one surface electrode of the piezoelectric ceramic disc, which is contacted with the flat plate, is connected with the double-strand electric wire in a welding way and protected by the metal shell to form a hood mechanical structure and form an electromagnetic shielding Faraday cage; the resin is filled in the hood, so that the whole hood has certain mechanical performance and can be simply, conveniently and accurately arranged on the flat plate; the piezoelectric ceramic disc is disc-shaped, semicircular or rectangular; the edges of the flat plate need to be kept flat or rounded; simultaneously:

a) the method comprises the following steps The acoustic-electric transducer is connected with the flat plate through bonding and is connected to the signal processing element through a conducting wire, and then the area of the flat plate occupied by the slope at the slope surface is filled with metal powder, so that the echo effect generated by reflection or refraction of ultrasonic waves at the edge of the flat plate is reduced;

b) the method comprises the following steps The flat plate is covered by a metal shell due to the area vacated by slope processing, the flat plate can be used for assembling the interface to enter other products, and the surface of the shell and the central surface of the flat plate are kept horizontal;

c) the method comprises the following steps The radian of the slope surface of the flat plate is less than or equal to 0.1 rad.

2. The interactive interface device of claim 1, wherein: four vertex parts of the flat plate are occupied by four groups of the acoustoelectric transducers respectively, and the position (xr, yr) of a click touch on the surface of the flat plate is deduced through a circuit and a program method; the derivation method is that the transfer time of the touch to different transducer groups is different according to the click; the click touch is generated by a rigid object in short-time contact with the flat plate.

3. The interactive interface device of claim 2, wherein: any one or more groups of the acoustoelectric transducers can utilize the flat plate as a diaphragm for voice input, selectively receive low-frequency sound wave signals through band-pass filtering, and record voice signals through an analog microphone.

4. The interactive interface device of claim 2, wherein: the interactive interface device is provided with a fifth group of acoustoelectric transducers, and is used for playing audio signals, namely a loudspeaker function, by selectively exciting sound wave signals for modulating audio on the flat plate; the fifth group of acoustoelectric transducers are disc-shaped or rectangular; the transducer for realizing the sound playing function consists of two piezoelectric ceramic discs, and under the working condition, vibration signals of the two discs have a phase difference of 90 degrees; the interactive interface device can realize that the audio signal is modulated by a high-frequency signal through programming; the fifth group of acoustoelectric transducers are arranged on the slope surface of the flat plate like the first four groups of acoustoelectric transducers and are covered with epoxy resin; through the characteristic that epoxy absorbs vibration to and audio signal plays according to the group time, avoid causing the signal saturation of other sensor groups.

5. The interactive interface device of claim 2, wherein: the interactive interface device has a circuit and a program component, can simulate a button on the flat panel through programming, and provides an interactive function of playing pre-recorded music, or transmits the position information (xr, yr) to other facilities for interactive use.

6. The interactive interface device of claim 2, wherein: the interactive interface device is provided with a circuit and a program component, and can establish a one-to-one corresponding relation between the detected click touch position (xr, yr) and the pixel on the computer screen in a wireless or wired mode; when a computer screen is projected on the surface of the flat plate, and the size of the projection screen is adjusted to be consistent with the characteristic size of the flat plate for detecting touch, the detected touch position can be coincided with the projection position, so that the function of a mouse cursor can be simulated; the function of a left mouse button is simulated by clicking once, and the function of a right mouse button can be simulated by clicking twice continuously in a short time; meanwhile, the recording function and the loudspeaker function can be connected with computer equipment or sound card equipment, and the function of playing videos or music is achieved during touch interaction.

7. The interactive interface device of claim 1, wherein: the interactive interface device has a flat surface, and can be integrally assembled into a desktop or a show window to realize: an interactive display show window, an interactive table, an intelligent bus station, a billboard or a public display board; or the floor is assembled into the ground, so that the interactive floor intelligent household product is realized.