MXPA99005934A - Grating transducer for acoustic touchscreen - Google Patents

Abstract

Un dispositivo de detección de tacto acústica, que tiene una superficie;y un transductor (11, 12) de onda acústica, que transduce una onda en volumen en el sustrato que se propaga a través del sustrato, a lo largo de un eje que intersecta la superficie, en donde la energía de la onda en volumen se acopla a una onda que tiene un modo de onda convertido, con la energía en la superficie y que se propaga a lo largo de la superficie por medio de los transductores (5a, 5b, 8a, 8b) de rejillas.

Description

GRID TRANSDUCER FOR ACOUSTIC TOUCH SCREEN TECHNICAL FIELD The present invention relates to the field of ultrasonic transducers, and more particularly to grid transducers for acoustic touch screens.

PREVIOUS TECHNIQUE Touch screens are input devices-for interactive computer systems. These are increasingly used commercially for applications such as information kiosks, restaurant order entry systems, and so on. - The dominant technologies of touch screens are resistive touch screens, capacitive touch screens and acoustic touch screens. Acoustic touch screens, that is, ultrasonic touch screens, are particularly convenient when the application demands a very durable contact sensitive surface and minimal optical degradation of the image that was displayed visually. Different types of ultrasonic transducers are known. The most common types used in acoustic touch screens are wedge transducers and the direct coupling between a piezoelectric transducer element and the tactile substrate. A transducer is a physical element or set of elements that convert energy from one form to another. This includes the conversion between acoustic wave modes and the conversion between electrical and acoustic energy. The transducers that are typically used are formed of a rectangular prismatic piezoelectric ceramic having surface-forming conductors, which are acoustically coupled to a surface, by mounting a flat surface of the ceramic element or the metal electrode that it is formed in the surface flow with a surface of an element of the substrate, for example the wedge material. A wedge transducer induces surface bond waves or plate waves within a substrate. The wedge transducer uses the phenomenon that acoustic waves are refracted when they are incident obliquely on a linking surface of different media. A typical wedge transducer typically consists of a plastic wedge, having a piezoelectric element mounted on one side, and the hypotenuse adhered to the substrate, which is for example glass. The piezoelectric element is coupled to a wave in volume in the wedge material. This wave in volume propagates at the critical angle, that is, the "wedge angle", to refract to or from a propagation wave horizontally in the glass. The wedge material is chosen to have a volume wave acoustic velocity that is lower that the phase speed of the desired mode on the touch substrate; the cosine of the wedge angle equals the radius of these two speeds. Wedge transducers can be used in this manner both to transmit, and to receive Rayleigh waves, Love waves and plate waves, such as Lamb waves. In contrast, direct-coupled or "shore" transducers typically provide a piezoelectric element that directly links to the substrate of the touch screen, such that a sound wave with appreciable energy is directly generated on a surface of the substrate. The interconnection performs in this way the mechanical function to connect the piezoelectric element to the substrate, as well as the acoustic function to be coupled to the desired acoustic mode. Figure 2B of U.S. Patent No. 5,162,618, which is incorporated herein by reference, illustrates a shore transducer that is used to send Lamb waves within a thin substrate. See also United States Patent Number 3,893,047, from Lardat. Shore transducers are used more naturally to couple with plate waves without nodes, as a function of depth in the substrate. Some work has been done to develop shore transducers that are coupled with Rayleigh waves. See Ushida, JP 08-305481 and JP 08-305482, which they are incorporated herein by reference. While the shore transducer is compact, this leaves the piezoelectric transducer unprotected. One type of known acoustic tactile position detector includes a touch panel or board having a configuration of transmitters placed along a first edge of a substrate to generate parallel or plate-surface bond waves simultaneously, which propagate Directionally through the panel to a corresponding configuration of detectors positioned opposite to the first configuration on a second edge of the substrate. Another pair of transducer configurations is provided at the right angles of the first set. The contact of the panel at a point causes an attenuation of the waves passing through the contact point, thus allowing the interpretation of an output from the two sets of transducer configurations, to indicate the coordinates of the contact. In U.S. Patent Number 3,673,327 and U.S. Patent Application Number 94/02911 to All, which are incorporated herein by reference, this type of acoustic position-tactile detector is shown. . Because the acoustic wave deviates, a portion of a wave that is emitted from a transducer that is transmitting will be incident on a set of reception transducers, allowing finer discrimination of the tactile position than transducers would allow for a simple one-to-one relationship to transmit and receive. These systems require a large number of transducers. A commercially successful acoustic touch screen system, called an Adler type acoustic touch screen, as shown in Figure 1, employs transducers efficiently, by means of spatially dispersing the signal and analyzing the temporal aspects of disturbance as indicative of the position. A typical rectangular touch screen thus includes two sets of transducers, each having a different axis aligned in a respective manner with the axes of a physical Cartesian coordinate system defined by a substrate. A transducer generates an acoustic impulse or train of impulses, which propagate as, for example, a thin Rayleigh wave along an axis, which intersects a configuration of reflective elements, each element at an angle to 45 ° and separated into correspondence to an integral number of wavelengths of the acoustic wave impulse. Each reflective element reflects a portion of the wave along a path perpendicular to the axis, through a wide region of the substrate that was adapted for tactile detection, to an opposite configuration and the transducer which is a mirror image of the first configuration and the transducer, while allowing it to pass a portion towards the next reflective element of the configuration. The transducer of the mirror image configuration receives an acoustic wave consisting of superposed portions of the incrementally varying wave portions reflecting the reflective elements of the two configurations, which are directed antiparallel to the impulse that was emitted. In this way the acoustic waves are collected, while the time dispersion information that characterizes the axial position from which an attenuated wave originated is maintained. The wave paths in the active region of the detector have characteristic time delays, and therefore a wave path or attenuated wave paths can be identified by means of an object that touches the touch sensitive region, by determining the synchronization of an attenuation in the composite return waveform. A second configuration of transducers is provided at the right angles to the first, and operates in a similar manner. Since the axis of a transducer corresponds to a physical coordinate axis of the substrate, the synchronization of an attenuation in the return wave indicates a Cartesian coordinate of a position in the substrate. The coordinates are determined sequentially to determine the position of the two dimensional Cartesian coordinates of the attenuation object. The system operates on the principle that one touch on the surface it attenuates surface bond or plate waves that have an energy density at the surface. An attenuation of a wave traveling through the substrate causes a corresponding wave attenuation that impacts the receiving transducer over a characteristic period of time. In this way, the controller only needs to detect the temporal characteristics of an attenuation to determine the position of the axial coordinate. The measurements are taken along two axes sequentially in order to determine a position of the Cartesian coordinate. See U.S. Patent Nos. 4,642,423, 4,644,100, 4,645,870, 4,700,176, 4,746,914 and 4,791,416, Re. 33,151, which are incorporated herein by reference. U.S. Patent No. 4,642,423 to Adler, which is incorporated herein by reference, refers to pseudo planarization techniques for rectangular touch screen surfaces that are formed by the solid angular sections of a sphere . As shown in Figure 1, the system transmits a short-time ultrasonic wave signal in the form of a burst by the acoustic wave transmission means 11 and 12, scattering the transmitted signal to the entire surface of an input range 15 of the coordinate through reflection members 13 and 14, which act as acoustic wave dispersers. The system receives the signal by the reception means 18 and 19 through the reflection members 16 and 17, which act as acoustic wave capacitors, and analyzes the signal that was received along the time base, for detect the coordinates that were indicated. A portion of the touch screen system where the wedge type transducer is located on the surface of the panel is inevitably higher than the surface of the panel. As shown in Figure 2, when a visual display is composed of a curved panel, such as a typical cathode ray tube, a space where a wedge-type transducer 23 can be located, frequently appears between a curved panel 21 and a bevel 22 covering the periphery of the curved panel 21. When a visual display is composed of a flat panel, such as a visual display of liquid crystal or a visual display of plasma as shown in Figure 3, there is no separation between a panel 24 and a bevel 25 on the periphery of the surface of the panel 24 covered with the bevel 25, whereby there is no space for the location of the wedge type transducer. When a wedge type transducer is employed, therefore, the ultrasonic type touch panel is not well suited for use with a flat panel. In this way, the type of configurations of visual displays and applicable accommodations that can be adapted, is greatly restricted. The known reflection configurations are generally formed of a glass frit that is covered by silk on a soda-lime glass sheet, which is formed by a flotation process, and which is cured in an oven to form a pattern of cheurón de interrupciones de vidrio elevadas. These interruptions typically have elevations or depressions of the order of 1 percent of the acoustic wavelength in the receiving transducer, the distance of the reflective elements can be decreased with the increasing distance from the transmitting transducer, or it can be altered the balance of the transmittance and the acoustic reflectivity of the reflection elements, allowing increased reflectivity with increased distance from the transmission transducer. Because the touch detector is generally placed in front of a visual display device, and because the reflection configuration is generally optically visible, the reflection patterns are generally placed on the periphery of the substrate, outside the area active detection, and hide and protect under a bevel. In order to further reduce the number of transducers, folded acoustic paths can be employed. Figure 11 of the U.S. Patent No. 4,700,176 teaches the use of a single transducer, both to transmit the wave, and to receive the sensory wave, using a single reflection configuration to disperse and recombine the wave. These systems therefore employ a reflection structure opposite to the reflection configuration. In this way, the acoustic wave 180 ° can be reflected off the edge of the substrate or a reflector configuration parallel to the axis of the transmission reflection grid and reflected back through the substrate to the reflection configuration and retracts its trajectory back to the transducer. The transducer, in this case, is multiplexed by time division to act as transmitter and receiver, respectively, in appropriate time periods. A second transducer, reflection configuration and reflection edge are provided for an axis at the right angles, to allow the determination of a contact coordinate along the perpendicular axes. A "triple transit" system provides for a single transducer which produces a sensory wave to detect contact on the two orthogonal axes, which produce and receive the wave from the two axes. See Patents of the United States of North America Nos. 5,072,427; 5,162,618 and 5,177,327, which are incorporated herein by reference. The vast majority of current commercial products are based on Rayleigh waves. Rayleigh waves maintain a useful energy density in the touch surface due to the fact that they are linked to the touch surface. A Rayleigh wave is a wave that has vertical and transverse wave components with substrate particles that move along an elliptical path in a vertical plane, including the axis of wave propagation, and the wave energy that decreases with increasing depth in the substrate. The shear and pressure / tension stresses are associated with Rayleigh waves. Mathematically, Rayleigh waves exist only in the semi-infinite medium. In feasible substrates of finite thickness, the resulting wave can be more accurately called an almost-Rayleigh wave. Here, it is understood that Rayleigh waves exist only in theory and therefore, a reference to it indicates an almost-Rayleigh wave. -For engineering purposes, it is sufficient for the substrate to be from 3 to 4 wavelengths of Rayleigh in thickness, with the objective of supporting the propagation of the Rayleigh wave during the distances of interest for the design of the touch screen. In addition to Rayleigh waves, acoustic waves that are sensitive to surface contacts, ie, a contact on 1 surface leads to a measurable attenuation of acoustic energy, including, but not limited to, Lamb , Love, polarized shear horizontally zero order (ZOHPS), and higher order horizontally polarized shear (HOHPS). See U.S. Patent Number 5,591,945, U.S. Patent Number 5,5,329,070, U.S. Patent Number 5,260,521, U.S. Patent Number 5,234,148, U.S. Pat. United States of America Number 5,177,327; United States Patent Number 5,162,618; and United States Patent Number 5,072,427. which are incorporated herein by reference. Like Rayleigh waves, Love waves are "waves bound to the surface", that is, waves linked or guided by one surface and not affected by the other surface of the substrates, provided that the substrate is sufficiently thick. In contrast to Rayleigh waves, the particle motion for Love waves is horizontal, that is, parallel to touch the surface and perpendicular to the direction of propagation. Only the shear stress is associated with a wave of Love. Another type of acoustic waves of possible interest in connection with acoustic touch screens, are plate waves. This includes the horizontally polarized shear plate waves of the lowest orders (ZOHPS) and higher (HOHPS), as well as Lamb waves of different symmetries and orders. It is known that the configurations of the reflection elements having a regular separation or increase in space can diffract or scatter the incident radiation, including the acoustic waves. The known Adler type touch screen design, which was discussed above, employs a reflection configuration to coherently reflect an acoustic wave at a predetermined angle. Touch screen designs, in accordance with U.S. Patent Nos. 5,072,427 and 5,591,945, which are expressly incorporated herein by reference, extend this principle, providing a reflection configuration that coherently reflects a acoustic wave at an angle previously determined on the surface, while converting a wave mode of the wave. In this way, it is known that the interaction of an acoustic wave with a diffraction grating can convert the wave energy between different wave modes. The contacts that detect the acoustic waves may include a finger or a punch that presses directly or indirectly on the surface through the cover sheet. See, for example, U.S. Patent Number 5,451,723, which is incorporated herein by reference, which employs a detector system acoustic wave of shear stress mode and shore transducers. The use of wedge transducers, which are frequently used in Rayleigh acoustic wave sensing detectors, makes it difficult to mount a cover sheet on the front surface, due to mechanical interference between the cover sheet or the wedge transducers. As with the design of the LCD touch monitor, the use of wedge transducers complicates the mechanical design and may limit the options. In the United States Patent Application Serial Number 08 / 610,260, which was filed on March 4, 1996, which is expressly incorporated herein by reference, an approach to directing these mechanical interferences is described. from the wedge transducers. As described herein, a wedge transducer may be mounted on a front surface bevel adjacent to the contact region, which separates the wedge transducer behind the front surface of the touch screen substrate, but incurs acoustic losses . Contrary to the needs of the liquid crystal display (LCD) visual touch display design, these designs typically add edge width to the touch screen. Masao Takeuchi and Hiroshi Shimizu, "Theoretical analysis of grating couplers for acoustic waves", Journal of the Acoustic Society of Japan, 36 (11): 543-557 (6/24/1980), which is incorporated herein by reference, describes a grid transducer and the theoretical framework of its operation. See also, the search essay Published by Masao Takeuchi and Hiroshi Shimizu of Tohoku University on "Unidirectional excitation of piano waves in a periodic structure" (in Japanese) (1991). See also, Melngailis and R.C. Williamson, "Interaction of Surface Waves and Bulk Waves in Gratings: Phase Shifts and Sharp Surface Wave / Reflected Bulk Wave Resonances", Proc. 1978 IEEE Ultrasonics Symposium, p. 623; Hermán A. Haus, Annalisa Lattes and John Melngailis, "Grating Coupling between Surface Acoustic Waves and Pia Modes", IEEE Transactions on Sonics and Ultrasonics, p. 258 (September, 1980). In a wedge transducer, the unconverted volume wave from the piezoelectric transducer that is not coupled to, for example, Rayleigh waves, does not enter the substrate of the touch screen and dissipates in the wedge material. In contrast, in a surface grating configuration, the energy of the wave in volume from the piezoelectric that is not converted to, for example, Rayleigh waves in the grid, will take the form of waves in volume or parasitic plate that are propagate in the material of the substrate itself. As Takeuchi et al. (1980) make clear, a theoretical upper limit of the conversion efficiency for the Wave energy in incident volume at Rayleigh wave energy is 81 percent, leaving a theoretical minimum of 19 percent of the wave energy in volume in the form of parasitic waves. Even this efficiency is difficult to achieve in practice; see the discussion of "factor F" in Takeuchi et al. (1980). Therefore, it is clear that a grid transducer has a significant disadvantage in relation to wedge transducers: the strong generation of parasitic waves. For typical applications of ultrasonic transducers, such as non-destructive testing, this strong generation of parasitic waves is often not acceptable. Even on touch screens, the perspective of generated significant parasitic waves propagating parallel in the plane of the substrate to the desired wave is considered problematic. Similar considerations apply to the sensitivity of the reception mode grating transducers for parasitic waves. It is known that undesirable parasitic waves can be a problem for at least some examples of acoustic touch screen design. For example, see Figures 13, 14 and 17, and the associated text of U.S. Patent No. 5,260,521, which is incorporated herein by reference in its entirety. The tactile recognition algorithms in commercial touch screen controllers require that the desired signal be free of interference from parasitic signals. R.F. Humphryes and E.A. Ash, "Acoustic Bulk-surface-wake transducer," Electronics Letters (Volume 5, No. 9) May 1, 1969, includes the discussion of a grid transducer that uses asymmetric grid teeth as a means to build a unidirectional transducer . This reference also considers a pair of gratings on the opposite surfaces of the substrate as a means to transfer the Rayleigh waves between the surfaces. The Patent of the United States of North America Number 5,400,788, Figures 12, 13 and 14, which is expressly incorporated herein by reference in its entirety, discloses a configuration of the transducer in which the gratings are used to couple the Rayleigh waves to the waves in volume. Interdigital transducers in a piezoelectric substrate generate Rayleigh waves that are converted by the grids to pressure volume waves, which are then coupled into an acoustic waveguide (which is also optionally an optical fiber). The interdigital electrodes and the grids, form sections of circular arcs. U.S. Patent No. 5,673,041, "Reflective mode ultrasonic touch sensitive switch," which is expressly incorporated herein by reference in its entirety, discloses a tactile detector ultrasonic that makes use of a thickness mode resonance of a touch panel substrate. A configuration of transparent piezoelectric elements, which is formed for example of polyvinylidene fluoride (PVDF), is bonded to the back side of the substrate (eg, glass). The electronics verify the impedance characteristics of the piezoelectric elements, which are coupled to the resonance of the thickness of the substrate. A touch of the finger absorbs the acoustic energy, dampens the resonance of the thickness and consequently alters the Q (quality factor) of the resonant system, and in this way changes the impedance characteristics of the piezoelectric coupled to the thickness resonance. This scheme uses in this way the known damping of the acoustic waves by means of an absorbent object, and does not employ a structure or dispersion grid DESCRIPTION OF THE INVENTION The present invention provides a transducer system for an acoustic touch screen in which an acoustically emitting element, for example, a piezoelectric element, generates waves in volume in a medium, which then interacts with a grid structure. to produce useful surface bond plate wave or wave, for example, a Rayleigh wave, a Love wave or an HOHPS wave. In this way, a wave in volume, which is coupled to a piezoelectric element, it interacts with the grid structure and is converted to a wave mode which tightens one or more surfaces of the substrate and has appreciable energy in at least one surface. Using these general principles, a variety of touch screen configurations are possible. Typically, the same volume wave modes are unsuitable for use on touch screens, and must be converted to more useful wave modes. According to the invention, the volume wave interacts with a grid on the surface that propagates at a non-zero angle with respect to the local area of the surface. Optionally, the grid may have a significant component within the volume of the substrate in addition to, or instead of, a surface grid structure. The grid itself comprises at least one dispersion center that can couple acoustic wave modes; practically, the conversion of the wave mode occurs with a set of periodic perturbations, which can be linear, curves, points, or other forms. A linear grid, for example, one whose elements are placed extended beyond the width of the incident acoustic beam, is considered a one-dimensional scattering element, and will typically produce scattered acoustic waves that diverge slightly along an axis. The elements that interact with a part of the acoustic wave, for example, are point scatter centers or elements short elongated, it can disperse a number of different sound waves, each potentially having a different waveform or spreading axis. Elements that are curved or aligned along curved shafts can act as acoustic lenses, which converge or diverge from the acoustic wave compared to a linear grid that otherwise has similar characteristics. The inventors of the invention have found, that when the waves in volume, which can be longitudinal waves (compression waves) and / or transverse waves (shear waves), propagate through the substrate to a structure of periodic disturbance on a surface of the substrate, waves in volume are converted into surface or plate bond waves by means of periodic disturbance. Then, the surface bond or plate waves can be used to detect with great precision, a contact position (a contact position or an entry position) in a touch-sensitive region of the panel, which, for example, can correspond to a visual display area of the panel, thereby mitigating the need for a wedge type transducer. In a typical embodiment, the waves are generated by an acoustic wave transducer in compression mode on a surface of the substrate, which generates a wave in volume in the substrate, directed towards the grid or the set of elements of dispersion. Surprisingly, while the grid transducers themselves have a significant interference-wave coupling in the substrate, the inventors have found that the effects of the parasitic signal are quite manageable for a complete touch screen incorporating the grid transducers. Another aspect of the invention provides "an acoustic transducer system, including Rayleigh wave transducers, suitable for polymeric substrates." U.S. Patent No. 5,162,618, column 5, lines 42-44, refers to to a plastic substrate for a touch screen that uses shear plate waves, no teaching is given as to how Rayleigh waves can be generated on a plastic substrate.The wedge angle opposite the piezoelectric element of a wedge transducer by the following formula: cos (?) = Vp (wedge) / VR (substrate) For a given material, the speed of the Rayleigh wave, VR, is typically about half the speed of the wave pressure, Vp To be able to design a wedge transducer, that is, for the cos (?) to be less than one, the velocity of the pressure wave in the wedge material must be less than about half e the speed of the pressure wave in the substrate. This can be done if the The substrate material, for example glass, has a relatively fast sound velocity and the wedge material, for example acrylic, has a relatively slow sound velocity. However, if the substrate is a polymer material and consequently has a slow sound velocity, it is difficult to find an acceptable wedge material with much slower sound velocity than is required. In order to make designs of polymer touch screens in which Rayleigh waves are generated and received on a practical polymer substrate, there is a need for an alternative wedge transducer. The present invention thus eliminates the consideration of the refractive characteristics of a wedge material, using instead a diffraction principle to convert the wave modes. In accordance with the present invention, the grid preferably takes advantage of the coherent dispersion of multiple scattering centers. In this way, a grid can be a configuration having at least one significant Fourier component that corresponds to the desired Bragg diffraction coupling between the wave in volume and the desired wave. The horizontal component of the wave vector of the wave in volume in this case is coupled to the wave vector of a plate or surface bond wave. A grid can be provided as a surface structure, with the wave in volume incident on the grid in An angle inclined to the surface of the substrate. Alternatively, the grid can be hidden on the substrate or not flattened. The basic principles of the grid transducer operation are largely independent of the details of the grid structure, although the symmetry of the grid structure can lead to directionality. Grids can be formed of elements that appear as slots, flanges, deposited material, filled slots, hidden structures (acoustically reflective elements below the surface of the substrate), which have different profiles, including rectangular, sinusoidal, serrated , and other symmetrical or asymmetric shapes. In fact, for a molded grating transducer for a polymer substrate, the flat edges of a sinusoidal grid are preferred. It is noted that, due to the symmetry and the separation of the elements, the function of the elements of the grid will be essentially the same for the fundamental frequency, although the grid will have different characteristics with respect to the harmonics. For the present purposes, a grid can be considered as a region of a detector subsystem in which the acoustic properties of the medium have been modulated, in such a way as to produce a distribution of scattering centers having significant Fourier transform amplitudes for one or more points in the vector space of the two-dimensional wave. A grid having multiple acceptance angles has a significant two-dimensional Fourier transform amplitude for two or more points in the vector space of the 2-D wave. The grid may be a flat grid or a volume diffraction structure, formed, for example, by selectively depositing the layers of the grid material. By attaching to multiple directions, some efficiency will be lost and more care will be needed to avoid parasitic signals; however, the reduced part count and the small size and mechanical simplicity of the design may be desirable under certain circumstances. For example, a single receiving transducer may receive both X and Y signals. In some cases, it may be convenient for manufacturing purposes to fabricate patterns or reflection gratings on strips of material that are then bonded to the rest of the substrate; see U.S. Patent Number 4,746,914, column 9. In this way, a bonded structure can be used for the convenience of manufacturing or packaging configuration. The emitting or sensing structure acoustically, which is part of the acoustic transducer, is typically a piezoelectric element, but is not limited. A transducer is a structure that converts energy from one form to another, and it can be bidirectional. For example, electroacoustic transducers, optoacoustic transducers, magnetoacoustic transducers, acousto-acoustic transducers (which convert energy between one acoustic wave mode and another), and thermoacoustic transducers, among others, are available. A piezoelectric element is typically in the form of a thin rectangular sheet having conductive portions that serve as electrodes with a piezoelectric responsive material in between. When an oscillating voltage signal is applied to the electrodes, the resulting electric field within the piezoelectric material, through the piezoelectric effect, causes the element to vibrate, depending on the nature of the piezoelectric material, the configuration of the electrodes, and the limitations Mechanical couplings. Conversely, if the element is subjected to mechanical oscillations, an oscillating voltage will appear on the electrodes. There are different options with respect to the mode of mechanical oscillations of the piezoelectric element. A common choice is the compression-expansion oscillation of the lowest order with respect to the thin dimension of the element; this element is coupled with waves in pressure volume or other acoustic modes, with a significant longitudinal component. Another option is an oscillation of shear stress of the lowest order, in which a surface, carrier of the electrode moves antiparallel to the opposite face; this element is coupled with the waves in shear volume and other acoustic modes with shear components. The direction of the shear movement can be designed to be any direction within the plane of the electrodes. More complex options are also possible. In accordance with one aspect of the present invention, different sets of detection waves propagating in the substrate can be distinguished according to their mode of propagation, by selectively coupling with the sensitive transducers in an appropriate manner. Typically, the piezoelectric elements are designed to have a resonant frequency at the operating frequency for the desired oscillation mode. For the compression oscillation of the lowest order, the resonant frequency is the pressure wave velocity in volume (in the piezoelectric material) divided by twice the thickness of the piezoelectric element, so that the piezoelectric transducer element is half the thickness of the wavelength. Similarly, a piezoelectric element of shear stress of the lowest order is half the thickness of a shear wavelength in volume. As used on a touch screen, the piezoelectric element is a mechanical damped oscillator due to the coupling to acoustic waves in the substrate. In one embodiment of the invention, the piezoelectric element has a linear series of band electrodes, which are driven individually. When they are coupled to the substrate, for example to a edge of a glass plate, with the series of electrodes placed along the thickness of the glass, a transducer is formed in phase configuration. In a simpler mode, the separation of the electrodes is one-half of the desired wavelength in volume, divided by the cosine of a desired propagation angle, allowing the alternating electrodes to be electrically parallel, and forming in that way a transducer of two selective electrodes, which produces acoustic waves both upwards and downwards diagonally in the substrate. More generally, each electrode of the phased configuration can be excited or analyzed separately, allowing coupling with acoustic waves having a wavelength longer than twice the inter-electrode spacing, which may allow the directional selectivity. The transmission transducer is excited with a sinusoidal waveform or pseudo-sinus waveform at the desired frequency from the controller. This burst typically has an energy spectrum with a maximum at a nominal operating frequency. Normally, the detector to be used at a specific frequency or set of frequencies, and therefore this parameter is previously determined. See U.S. Patent Nos. 4,644,100, Re. 33,151, and Number -4,700,176, which are incorporated herein by reference. The basic concept of a grid transducer is as follows. A piezoelectric element is bonded directly onto the substrate and coupled to the waves in volume within the substrate. Then, these waves in volume are coupled, by means of a grid, to the desired acoustic mode for the operation of the touch screen. The desired acoustic mode can be a Rayleigh wave. In contrast to wedge transducers, grid transducers do not require the wedge and consequently have a reduced mechanical profile. This is particularly important for LCD touch monitors. The grid transducer is particularly convenient because it eliminates the need for precise angular alignment of a sub-assembly of the wedge transducer on the surface of the substrate. In a grid transducer, the angular alignment of the grid has similar tolerances. However, these tolerances can easily be met-through standard printing processes. The tolerances are much more relaxed for the placement of the element- piezoelectric on the surface of the substrate. The gratings 5a ', 5b', 8a ', and 8b' of Figure 4, which can be elements that are parallel or inclined to the axis and, or curved or interrupted elongated, couple the waves in volume and the waves of surface or plate by the two-dimensional Bragg scattering condition in the horizontal plane (xy) that is defined by the local surface of the substrate. Let x represent the wave vector of the surface bond or plate wave. This is a vector in the X-Y plane as defined in Figure 4, whose direction is the propagation direction of the acoustic wave and whose magnitude is 2tr / ?, where? is the wavelength of the surface bond or plate wave. Let's let (xB) || represent the horizontal projection, that is, the components x and y, of the wave vector of the wave in volume. Let TB be defined as the angle between x and (xB) || , TBT being the angle for the conversion of the wave in volume to the surface bond or plate wave, and being TBR the angle for the conversion of surface wave or plate to wave in volume, provided with different notation to denote that the volume waves that are coupled may differ and in this way, the respective scattering angles may differ. Let xB be a significant two-dimensional Fourier component of the grid. The two-dimensional Bragg scattering condition is met, if the following equation: ± xB = x - (xB) || There are many special cases for this two-dimensional Bragg scattering condition. Forward some examples are given. In the special case where x and (xB) || are parallel, that is, TE = 0o, and that the grid is a periodic structure of linear grid elements, perpendicular to X with separation p, then the previous relation reduces the following scalar condition, where n is an integer: 27rn / p = x - xBsen? B In addition, if the desired surface bond or plate wave is a wavelength of Rayleigh? R (and the wavelength of the wave in volume is? B), this ratio reduces further The following equation: TB = Arcsen (? B /? R + n? B / p) (n = ..., -3, -2, -1,0,1,2,3, ...) (the ) The internal angle TB in the equation a, can generally be selected from the range (in radians) of -tr / 2 < TB < tr / 2, preferably -3tr / 8 = TB = 3tr / 8, and more preferably -7r / 4 < TB < tr / 4. The wave that is used for the detection contact-may be an acoustic wave which is detectably disturbed by a contact on a surface of a substrate. There are many options for the choice of surface link or plate wave modes. Rayleigh waves they have excellent sensitivity to touch and are inherently confined to a thin volume near the touch surface even for a substrate of arbitrarily large thickness. Horizontally polarized shear waves have the advantage that they are weakly coupled to liquid or gel-like contaminants, such as water and silicone-rubber seals. An inhomogeneous substrate can, in addition to supporting the propagation of other types of waves, adapt in particular to support the propagation of horizontally polarized shear waves having asymmetric surface energy density, including Love waves, which are horizontally polarized shear waves near the tactile surface, such as Rayleigh waves. Lamb waves in a sufficiently thin substrate provide yet another option for the choice of acoustic wave mode. There are many engineering exchanges involved in the optimal choice of acoustic mode for a given application. In this context, Love waves can be supported by a higher substrate portion having a lower phase velocity interconnected with a lower substrate portion having a higher phase velocity. _ Similar wave types, generally classified as polarized shear waves hor-Lzontally, can be supported by phase velocity gradients vertical of a more complex nature. A sandwich of a lower speed layer on a fast speed layer on an acoustically absorbing layer can withstand Love's waves and simultaneously filter the parasitic waves. In this way, the substrate can comprise layers having different acoustic propagation properties and / or acoustic interconnections. The substrate can be formed as a flat plate with a rectangular shape or a non-rectangular shape, such as a hexagonal plate. Alternatively, the substrate may be curved along one or both of the axes as a cylindrical, spherical or ellipsoidal surface or surface, or may have other configurations. Spherical substrates of large solid angle, and completely cylindrical are possible. For example, a polygonal tactile detector with reflectance configurations on each side and transducers at vertex c can be provided. This invention is not limited to the geometry of the standard rectangular detector. It is noted that, for the purposes of this application, the substrate need not be a single monolithic structure, but rather a set of acoustically coupled elements that may be homogeneous or non-homogeneous. The acoustic path for the transmission transducer to the receiving transducer can optionally pass through the regions of the substrate that were bonded together as part of the manufacturing process. - It is noted that, in accordance with the concepts established in the pending patent application of the United States of America serial number 08 / 615,716, filed on August 12, 1996, which is expressly incorporated herein as a reference, the low curvature of the panel is not required, and in fact the grid transducer present can be applied to a large number of different acoustic contact input detection geometries, including notoriously non-planar surfaces. U.S. Patent Application Serial No. 08 / 615,716 also covers the use and analysis of redundant multiple and / or detection waves. A large substrate can also be employed in, for example, a large white board application, in which the substrate is sensitive to touch over a large area. Acoustic detectors of the Adler type have been considered for use in electronic white boards; see Figure 10 and the associated text in the E.P. 94119257.7, by Seiko Epson. In a white board application, the substrate does not need to be transparent, and therefore can be formed of an opaque material such as aluminum. Conveniently, aluminum and some other materials can be coated with an enamel with a relatively slow acoustic phase propagation rate, thus supporting a Love wave with high touch sensitivity (in relation to the stress plate wave modes _ horizontal cutter) on the front surface. Suitable glasses to form the substrate include soda-lime glass; glass containing boron, for example, borosilicate glass; glass containing barium, strontium, or lead, and crown glass. See, for example, U.S. Patent Application Serial No. 08 / 904,670 to Tsumura and Kent. Other materials that have acceptable acoustic losses can also be used, including, but not limited to, aluminum and steel. Under certain conditions, suitable substrates can also be formed from a polymer, for example, Styron, a low acoustic loss polymer from Dow Chemical. Suitable substrates can also be formed from substrates having non-homogeneous acoustic properties, for example a laminate. The laminate can conveniently support the propagation of the Love wave with the acoustic wave energy concentrated on the front surface, for example, a borosilicate glass or the Schott B270 glass-soda lime laminate or enamel on aluminum . In this way, a tactile-type coordinate input device according to the present invention comprises a propagation medium having a surface, a surface on which waves of propagation can be propagated. surface or plate bond, transmitting means for propagating waves in volume in an oblique direction towards the surface of the propagation medium from the lowest part of the propagation medium and producing the surface bond or plate waves by means of periodic disturbance, a visual display area that is formed on the surface of the propagation medium and can be touched, by reflecting the means provided on the two lateral sides opposite one another at the periphery of the visual display area and for propagating the link waves surface or plate from the transmission means over the entire area of visual display, from one or both of the lateral parts, as well as to focus or converge the surface bond or plate waves that propagated in the part of the other side, and receiving means for converting the focused surface or plate-bond waves into waves in volume by means of a perma- dica, propagating waves in volume in an oblique direction toward the lowermost part of the propagation medium and receiving the waves propagated in volume. In some embodiments according to the present invention, the propagation means may comprise first piezoelectric means which are placed in the lower part of a first corner portion of the propagation means, in response to an electrical signal and first grid means for convert the waves into volume from the first medium piezoelectric in surface waves on the surface of the propagation medium, and the receiving means may comprise second grid means for converting the surface waves into waves in volume on the surface of the propagation medium and for propagating the waves in volume in an oblique direction towards the lower part of a second corner portion of the propagation means and second piezoelectric means for receiving the volume waves that were obtained after conversion by the second grid means in the lower part of the second corner portion and producing an electrical signal. One embodiment of the invention provides a touch screen system of the Adler type, which employs grid transducers to couple the piezoelectric elements to the detection wave in the substrate. In this way, the touch screen provides a coordinate input device system comprising a panel having a symmetrical visual display area laterally, on which ultrasonic surface bond or plate-wave waves can propagate. In a typical system of four transducers, two pairs of transducers are provided respectively for the X and Y axes. For each transducer, an inclined surface is provided in a corner portion of the panel, with a piezoelectric transducer positioned on the inclined surface. The piezoelectric element couples the waves in volume that propagate to the along an oblique axis with respect to the transmission disturbance region at the periphery of the visual display area, in which a grid structure is placed. The grid couples the waves in volume with the surface or plate-bond waves, thus allowing a wave-volume transducer to interact with the surface-link or plate-wave. These surface bond or plate waves travel along an axis on which a reflex configuration (reflection grid) is provided, near a peripheral edge of the panel. Each element of the reflex configuration couples part of the surface link or plate wave with the sensing wave traveling through the panel, and transmits part to an adjacent element, thereby coupling a scattered detection wave from the region sensitive to the entire touch towards a thin acoustic beam, which is coupled with the transducer. In this way, each transducer can either transmit or receive an acoustic wave, in a symmetrical manner. The two pairs are placed at the right angles to define a coordinate system. It is noted that the grid can provide a focusing function to compensate for the scattering of the acoustic beam. The acoustic path can also be found with a limit of reflection between the outward dispersions of the transmission and reception configurations. The reflection link can use the coherent dispersion from a superposition of scattering centers, and if so, can be designed using similar principles as for the reflection configurations that follow the segments of the acoustic trajectories. Note, however, that for the limits of reflection, it might be convenient to use reflection elements that disperse more strongly. In accordance with the present invention, it is understood that these reflection limits may have the useful significant Fourier component, which corresponds to a reflection of a wave, with or without change in mode, in the same plane, or may correspond to a mode conversion from a wave, for example, traveling in the plane of the surface, within a wave in volume that is directed at an angle inclined to the surface. Sometimes engineering care might be required in the configuration design to minimize the creation of undesirable parasitic acoustic trajectories, which could result in signal artifacts. When grid transducers are used, these parasitic trajectories should be considered in three dimensions. The present inventors have found that, in spite of the generation of significant parasitic sound waves along the piezoelectric transducer, feasible modalities can be produced. On an Adler type touch screen, the acoustic wave interacts with the acoustic reflection configurations. Reflection configurations serve as filters narrow band for both the wavelength and the propagation angle. In this way, a reflection configuration has a great directional sensitivity which, in conjunction with the directional sensitivity of the transducer, serves to limit the angular acceptance of the system. Thus, in systems where parasitic volume waves are of relatively low energy, the interference wave energy rarely causes substantial interference in the received electronic signal. Assuming that the direct trajectories of the parasitic waves are not available or outside the window of useful time, and that the trajectories that were reflected, which would be within the time window, are attenuated, no extraordinary efforts are necessary to block the parasites. In the event that a parasitic interference path does prove to be problematic, typically a small change in the geometry of the tactile detector could eliminate the problem. Where there are parasitic volume waves present in the high amplitude, the parasitic attenuation design considerations may be important. When a grid is used to interconvert the wave modes, at most 81 percent of the energy of the incident acoustic wave is coupled from the wave in volume with a particular desired acoustic waveform. In this way, at least 19 percent of the energy is reflected or dispersed of the incident wave as parasitic wave energy, which travels frequently parallel to the desired wave. According to the present invention, therefore, the desired wave can be selectively dispersed along a different axis from the parasitic waves that were reflected or scattered, and / or the system is provided with one or more mechanical filters, such as filters of reflection or mode selection configurations, or electronic filters, such as time gate systems, to reduce interference from parasitic waves. Another particularly convenient technique that reduces the effects of parasitic waves, is to use a piezoelectric element of shear wave mode, which generates a volume wave in shear mode at an appropriate acute angle with respect to the link wave surface or plate. This modality provides at least two advantages. First, a reflected wave energy propagates antiparallel to the desired wave mode, and is therefore more easily attenuated by means of the absorbent material that is applied to a surface along its path. Second, the volume wave of the shear mode is coupled only to the desired surface bond or plate wave, making the factor "F" in accordance with Takeuchi et al. (1980) equal to one, implying efficient wave conversion . The touch screen is typically associated with a_ control system, which has a number of functions. First, an electronic signal is generated, which excites the transducer to generate an acoustic wave which forms the set of waves in a subsequent manner. Then, a transducer receives the set of waves, and transduces them to an electrical signal. The electrical signal is received, retaining significant information co-a relatively high data rate in a low level control system. In many modalities, it is not necessary to capture the phase information that contains the signals that were received. However, in some cases, it may be convenient to do so. An intermediate level control system, often combined in a structural way with the low level control, processes the data that was received, seeking to identify and characterize the disturbances. For example, in one mode, the intermediate level control filters the signal, performs the line-base correction, and determines a signal ratio with a threshold, and inputs the signal to eliminate the signal representing the acoustic paths. parasites that have an acoustic delay that is too short or too long. A high level control analyzes the signal disturbances and outputs a contact position. Therefore, the control system as a whole has the functions of exciting an acoustic wave, receiving the portions of the acoustic wave that carry the contact information as a disturbance, and analyzing the portions that were received to extract the characteristics of the contact, for example, the position. The scope of the present invention includes modalities in which one or more subsystems are of the positive signal type. Here, "positive signal" refers to the use of the desired acoustic trajectories for which a contact induces the conversion so that it is required to complete the acoustic path, or produces a wave that changes in phase from the wave of origin. Therefore, the signal disturbance is the generation of a signal amplitude in a delay time for which the previous signal amplitude was small or zero. See U.S. Patent Pending Application Serial No. 08 / 615,716, which was filed on August 12, 1996. The excitation function may be a series of pulses or pulses are emitted formed in a defined pattern, which it has a substantial energy spectrum density at a nominal operating frequency or frequencies. Because this impulse is of limited duration, it has a finite bandwidth. For example, Elo TouchSystems manufactures a controller that can excite 5.53 MHz tone bursts with durations in the range of 6 to 42 oscillations, resulting in excitation of the wide frequency band, due to the finite duration of the excitation, in comparison with, for example, the bandwidth of the configurations of reflection. This electronic pulse train typically drives a piezoelectric transmission element. Where high flexibility of control over the burst of excitation is desired, a direct digital synthesizer can be employed, such as AD9859 from Analog Devices. Although the systems according to the present invention have been constructed without the substantial interference of parasitic signals, some configurations may allow parasitic signals of limited duration to interfere with the desired signal. In such cases, it may be desirable to provide one or more partially redundant detector subsystems, which have different parasitic signal sensitivities. In this way, where a signal or a portion thereof from a transducer subsystem becomes useless, a signal can be processed from other transducer subsystems to allow, in spite of this, position determination. contact. Therefore, in accordance with this embodiment of the invention, three or more transducer subsystems can detect an acoustic signal disturbance, with different sensitivity for parasitic or potentially parasitic signals. In addition, where the parasitic signals do not interfere, additional information may be used to provide further information and functionality, including processing of the anti-shading and multi-contact detection algorithm.

Therefore, it is an object of the present invention to provide an acoustic tactile sensing device and method that employs a substrate with a surface and an acoustic wave transducer to transduce a wave in volume into the substrate, which propagates through the substrate along an axis that intersects the surface, where the energy of the wave in volume is coupled to a wave that has a wave mode converted with appreciable energy on the surface and that propagates along the surface. A disturbance of the converted wave mode is detected. The acoustic wave mode coupler is, for example, an element or set of diffraction elements acoustically. Typically, a system will include means to detect a disturbance of the energy of the wave that was converted. It is another object of the invention to provide an acoustic touch screen, comprising a propagation means having a surface for the propagation of an acoustic wave along the surface, an emission element for generating a wave in volume in the medium propagation, a first mode converter for producing the acoustic wave from the wave in volume, a second mode converter for receiving the acoustic wave from the first mode converter and producing a corresponding wave in volume, and an element of reception to receive the wave in volume from the second mode converter, where at least one of The mode converters comprise a set of at least one wave scattering element or a diffraction wave mode coupling structure. It is an additional objective of - according to the present invention, to provide a substrate for an acoustic detection device, having a central region, and a pair of surfaces, comprising an acoustic transducer, coupled to the substrate, to produce a wave in volume therein, having a propagation axis intersecting at least one of the surfaces; a set of at least one scattering element, which forms close to one of the surfaces, adapted to convert the acoustic wave energy of the wave into volume, to a coherent wave having appreciable energy in one of the surfaces; and means for the reflection portions of the acoustic wave energy that was converted through the central region. The acoustic wave of the reflection means is spatially dispersed. It is also an object of the present invention to provide a system wherein the source of the acoustic wave comprises the means for propagating the waves in volume in an oblique direction towards the surface of the substrate. It is a further object of the invention to provide a system where the wave in volume is coupled to another wave mode, by interacting with at least one scattering center on or in the substrate. It can configure the center of dispersion as a set that provides a periodic disturbance of the substrate or as a grid structure. In accordance with the present invention, it can be. eliminate or relocate wedge transducers from acoustic touch screen designs, potentially providing improved front surface free space and improved environmental resistance. The elimination of a wedge requirement having a relatively low acoustic propagation velocity, in comparison with the substrate, allows the use of substrates of slow acoustic propagation speed, such as plastics. It is another object in accordance with the present invention to provide an acoustic touch screen system having transducers that have low alignment sensitivity and potentially have low manufacturing costs. It is still another object in accordance with the present invention to provide transducers that produce converging acoustic waves or provide other functionality of focusing or acoustic lenses. These and other objectives will become apparent. For a complete understanding of the present invention, reference should be made to the following detailed description of the preferred embodiments of the invention, as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the invention will be shown by the drawings of the Figures, in which: Figure 1 is a schematic perspective view showing an acoustic touch screen device of the prior art; Figure 2 is a schematic cross-sectional view showing the relationship between a curved panel and a bevel; Figure 3 is a schematic cross-sectional view showing the relationship between a flat panel and a bevel; Figure 4 is a schematic view for explaining a conversion mechanism between surface or plate bond waves and waves in volume; Figures 5 and 6 are schematic front and side perspective views, respectively, showing an embodiment of a coordinate input device in accordance with the present invention; Figure 7 shows a received acoustic waveform with a contact-induced disturbance; Figure 8 shows a grid transducer device in accordance with the present invention, with a direct path, piezoelectric transducer of rear bezel mounting compression, and obtuse incident angle, with a front bevel and surface seal, in front of a visual display of flat panel; Figure 9 shows a grid transducer system in which the projection of the propagation axis of the wave in volume in the plane of the substrate differs from the axis of propagation of the wave that was converted; Figure 10 shows a grid transducer device according to the present invention with direct path, rear mounted compression mode piezoelectric transducer, having a thickness resonance in the substrate between the piezoelectric transducer and the dispersion elements; Figure 11 shows a schematic equivalent circuit of the piezoelectric transducer-substrate system: Figure 12 shows a grid transducer device according to the present invention with a reflected path, piezoelectric transducer mounted on the front bezel that produces a wave in volume of shear stress mode, and obtuse incident angle; Figure 13A shows a grid transducer device according to the present invention in a substrate that supports a Love wave with a direct path, piezoelectric transducer mounted in a rear bevel mounting shear, and obtuse incident angle; Figure 13B shows a grid transducer device according to the present invention on a substrate that supports a Love wave with a direct path, Piezoelectric transducer mounted in front shear mounting shear stress, and obtuse incident angle; Figure 14A shows a grid transducer touch screen system in accordance with the present invention, having grids which emit a converging acoustic wave; Figure 14B shows a schematic figure of the mode conversion and focus conversion effects of a curved grid element; Figure 15A shows a grid transducer device in accordance with the present invention with a direct path, piezoelectric transducer mounted rear internal bezel, and acute incident angle, in a polymer substrate; Figure 15B shows a grid transducer device according to the present invention with a piezoelectric piezoelectric mode mounted edge transducer, path reflected off a rear internal bezel, and acute incident angle; Figure 16 shows a grid transducer in accordance with the present invention with a resonant mounted piezoelectric transducer, having an asymmetric grid structure that provides unidirectional acoustic wave emissions; Figure 17 shows a grid transducer of according to the present invention, with a resonant mounted piezoelectric transducer, having a transducer positioned asymmetrically with respect to the grid structure, which selectively provides directional acoustic wave emissions; Figures 18A and 18B show two modes of the grid transducer according to the present invention, with a resonant mounted piezoelectric transducer, having a grid structure with asymmetric elements, and a grid structure in compensation layers, respectively, which provides selective directional acoustic wave emissions; Figures 19A and 19B show a grid transducer according to the present invention with segmented reflection configurations, each segment of the reflection configuration being associated with a grid transducer structure; Figure 20 shows a grid transducer according to the present invention on a substrate which supports the propagation of the Love wave, where the wave of Love converted travels at the right angles to the axis of wave propagation in volume; Figure 21 shows a grid transducer according to the present invention, which operates without reflection configurations; Figure 22 shows a grid transducer according to the present invention, wherein the grid couples two different waves to two piezoelectric transducers; Figure 23 shows a grating transducer according to the present invention having a complex piezoelectric transducer element for directing the coupling with a wave in volume in the substrate; Figure 24A shows a system in accordance with the present invention, with a pair of grid structures that transfer the acoustic energy between a back surface and a front surface of the substrate; Figure 24B shows how a tactile sensing system employing the system shown in Figure 23A has a simplified front surface architecture, without piezoelectric elements or wedge transducers; Figure 24C shows the back surface of the touch detector system according to Figure 23B, wherein an acoustic transducer, the reflection configuration and the elongated grid structure on the back surface of the substrate are provided, while allowing the tactile sensitivity of the front surface; Figure 25 shows a grid transducer according to the present invention with two significant acceptance angles in the plane of the substrate and coupling in this way two different converted waves; and Figures 26A and 26B show a system in accordance with the present invention, showing the wave paths for a hemispherical detector system employing grid transducers in a Mercator projection and plane view, respectively.

MODES FOR CARRYING OUT THE INVENTION Now preferred embodiments of the invention will be described with respect to the drawings. Similar characteristics of the drawings are indicated with the same reference numerals. The well-known principle of reciprocity of acoustic devices implies that the nominal transducers of transmission and reception can perform any of the two functions. Therefore, in the embodiments described below, it should be understood that acoustic transducers can transmit or receive acoustic signals, or both.

EXAMPLE 1 Figure 5 is a schematic perspective view showing an embodiment of a coordinate input device, in accordance with the present invention. Figure 6 is a schematic perspective view for illustrating a disturbance region or diffraction region by means of the rack. The coordinate input device in this embodiment comprises a propagation means 1 having a visual display area 2 that is adapted to touch, which is symmetrically laterally in the direction of the X axis and the Y axis that are formed in its surface, and having a surface, surface in which the surface or plate-bonding waves can be propagated.The medium 1 is coupled to a transmission transducer to propagate the waves in volume (which can be in the manner of pressure or shear stress mode), in an oblique direction towards the surface of the propagation medium 1 from the lowermost part of the propagation means 1, and which produces surface or plate bond waves in the directions of the X axis and the Y axis by means of a disturbance X-axis transmission means include the piezoelectric transducer 4a, which is mounted "on the inclined surface 3a, and the grid 5a that is formed on the medium 1, and the med The Y axis transmitting signals include the piezoelectric transducer 4b which is formed on the inclined surface 3b of the medium 1 and the grid 5b. In this embodiment, the propagation means 1 is composed of an isotropic flat panel which is formed of soda-lime glass having beveled edges. The transmission means 3a, 4a, 5a and 3b, 4b, 5b mentioned above, respectively comprise the inclined surfaces 3a and 3b which are formed in the first adjacent corner portions corresponding to the regions of transmission disturbances, in the directions of the X axis and of the Y axis in the lower part of the propagation means 1, the piezoelectric transducers of the first piezoelectric means 4a and 4b which are placed in the inclined surfaces and to emit the waves in volume in an oblique direction towards the regions of transmission disturbance on the surface of the propagation medium 1, in response to an electrical signal, and first gratings 5a and 5b to convert the waves into volume that propagated in the propagation medium from the piezoelectric transducers within the surface waves in the transmission perturbation regions on the surface of the propagation medium 1. In addition, the orthogonal projection planes from the inclined surfaces 3a and 3b in the original regions , they cross each other in the regions of disturbance in the periphery of the a visual display 2 on the surface of the propagation medium 1 (a transmission perturbation region on the X axis and a transmission disturbance region on the Y axis), and the gratings 5a and 5b are respectively placed in the regions of disturbance. The grids of the first conversion means 5a and 5b, comprise a plurality of linear grids (grids or lattices) that extend in the direction perpendicular to the direction of travel of the waves in volume that propagated from the transducers piezoelectric 4a, 4b almost in parallel with each other and they are placed periodically and, by the same, waves in volume and surface waves can be converted into one another. The surface or plate bond waves from the transmission means 3a, 4a, 5a in the direction of the X axis and the transmission means 3b, 4b, 5b in the Y axis direction propagate in the directions of the axis And y of the X axis on the complete visual display area 2, by means of reflection comprising first reflection configurations 6a and 6b and second reflection configurations 7a and 7b, and surface bonding or plate waves are directed or converge propagated in the directions of the X axis and the Y axis, and are received by the reception means 8a, 9a, 10a and 8b, 9b and 10b, respectively. More specifically, the first reflection configuration 6a of the X axis is formed to propagate the surface link or plate waves from the transmission means 3a, 4a, 5a in the direction of the Y axis from the direction of the X axis with the disturbance region of periodic transmission at its point of origin, on a lateral part extending in the direction of the X axis at the periphery of the visual display area 2, and the second reflection configuration 7a of the axis is formed X to reflect the surface link or plate waves in the direction of Y axis, by the first reflection configuration 6a of the X axis, and direct the surface bond or reflected plate waves in a reception perturbation region in the direction of the X axis, in the other lateral part opposite the first lateral part in the periphery of the visual display area 2. In addition, the first reflection configuration 6b of the Y axis is formed to propagate the surface link or plate waves ^ from the transmission means 3b, 4b, 5b in the direction of the X axis from the direction of the Y axis with the transmission disturbance region at its point of origin, in a lateral part extending in the direction of the Y axis at the periphery of the visual display area 2, and the second reflection configuration 7b of the Y axis to reflect the surface link or plate waves in the X axis direction, by the first reflection configuration 6b of the Y axis, and direct the surface link waves or of plate reflected in a reception disturbance region in the direction of the Y axis, in the other lateral part opposite the lateral part mentioned above in the periphery of the visual display area 2. Each of the reflection configurations can transmit a part of the surface bond or plate waves and may reflect them. The reflection configurations 6a, 6b, 7a and 7b make it possible to propagate surface link or plate waves, from the transmission means in the direction of the X axis and the transmission means in the direction of the Y axis, over the entire visual display area 2, as well as directing the surface bond or plate-propagating waves in the visual delink area 2, in the regions of respective reception disturbances of the X and Y axes. The reception means 8a, 9a, 10a and 8b, 8b and 10b convert the surface or plate bond waves, which have propagated and converged in the deployment area visual 2, in waves in volume, and propagate the waves in volume in an oblique direction towards the lower part of the propagation medium 1 to receive the waves in volume that propagated. Specifically, the receiving means comprise the gratings of the second conversion means 8a and 8b placed in the reception disturbance regions, adjacent to the second reflection configurations 7a and 7b and to convert the surface or plate-bond waves. in waves in volume, as well as propagating the waves in volume in an oblique direction, towards the lower part of the propagation means 1, the inclined surfaces 9a and 9b in the end regions of the second corner portions corresponding to the regions of projections that were refracted by means of the grids 8a and 8b in the lower part of the propagation medium 1, and the piezoelectric transducers of the second piezoelectric means 10a and 10b placed in the inclined surfaces and to receive the waves in volume that were obtained after the conversion through the grids 8a and 8b and generate an electrical signal. The grids of the second conversion means 8a and 8b comprise, in the same way as the grids of the first conversion means 5a and 5b, a plurality of linear gratings that extend and are placed periodically and parallel in the perpendicular direction. with respect to the direction of the wave travel in volume, towards the piezoelectric transducers 10a and 10b. The signal received by the piezoelectric transducers 10a and 10b is fed to detection means (not shown) to analyze the signal. In the detection means, a disturbed component is detected caused by the contact of the visual detachment area 2, together with a corresponding time delay, to detect a contact position or a contact region in the visual display area 2. volume waves produced by the piezoelectric transducers 4a and 4b, traveling straight in the propagation medium 1, are obliquely incident at the interconnections of the propagation medium 1 and the transmission disturbance regions, including the gratings 5a and 5b, and they become surface bond and plate waves. The surface bond or plate waves propagated in the propagation medium 1 are diffracted in one direction oblique in the regions of reception disturbance, including the gratings 8a and 8b, to become waves in volume. In this coordinate input device, when an electrical signal is fed to the piezoelectric transducers 4a and 4b, the waves in volume are produced by the vibration of the piezoelectric transducers, and the waves in volume can be converted into surface link waves or of plate by the grids 5a and 5b in the disturbance regions, so that the surface bond or plate waves in the X-axis and Y-axis directions can be propagated through a plurality of paths (routes) in the area of visual separation 2, through the first means of reflection. Therefore, when a finger or the like touches the visual gap area 2, the surface link or plate waves are disturbed, and the surface link or plate waves, including the disturbed components, are directed or converged on the reception disturbance regions by means of the second reflection means. In the receiving regions, the surface-link or plate-wave waves are converted into waves in volume, by the gratings 8a and 8b, and the waves are converted into volume in an electrical signal by the piezoelectric transducer 10a or 10b. The gratings 5a, 5b, 8a and 8b for the disturbance are thin, for example much less than the acoustic wavelength in height, so that the surface of the propagation medium can be relatively smooth in comparison with the mechanical profile of a wedge-type transducer. Therefore, a touch panel according to the present invention can be mounted behind a chamfer with relatively low clearance. Although the species of the propagation medium is not particularly limited, a panel is used on the surface of which surface or plate-bond waves and, in particular, ultrasonic surface-link or plate-wave waves can be propagated. An area of visual detachment of the panel includes a range that can be touched (i.e., a coordinate input range), and is generally formed in a symmetric manner laterally as in the embodiment mentioned above and particularly, a form symmetrically linear (in particular, a rectangular shape). The propagation means that was built as a panel generally has transparency with the aim of making a liquid crystal screen, fluorescent to the vacuum, another visual display of flat panel or similar visible. A preferred propagation medium is transparent and isotropic. The periphery of the visual detachment area, i.e. one end of the propagation means such as the panel, can generally be covered with a bevel.

The inclined surface can be formed respectively in the portions corresponding to an original region and a final region in the lower part of the propagation medium, or it can be formed in all the corner portions between the lateral surfaces and the lower surface of the propagation medium such as the panel, as shown in Figure 5. The disturbance cycle of the grids, i.e. the interval or inclination of the grids, can be selected in the regions of transmission or reception disturbance within of a range of, for example, about 0.01 to 10 millimeters, preferably about 0.1 to 5 millimeters and more preferably, about 0.3 millimeter, in accordance with the wavelength of the waves in volume in the propagation medium and the wavelength of the surface waves on the surface of the propagation medium. The number of grids and their width is not particularly limited, and, for example, the number of grids is approximately 3 to 10, and the width, that is, the dimension of the edge region of the substrate of the grid. grid, is approximately 0.01 to 10 millimeters. The thickness (height) of the grid can be selected within a range of no more than 5 millimeters, for example, from about 0.01 to 3 millimeters, preferably from about 0.1 to 3 millimeters and more preferably approximately 0.1 to 1 mm. The grids can be formed by screen printing or other technology. The grids can also be formed by corrosion, cutting or grinding, or ablation, or by other methods of material removal. The grids can also be formed by molding, hot stamping, or by modifying 'after the manufacture of the substrate properties. The elements of the grid can vary in height and / or width, similar to the elements of a reflection configuration, to balance the reflectivity and transparency on the grid. For example, a modulated grid of monotonic height can be used to provide unidirectional directionality to the grid. The reflection means need not be composed of a reflection configuration, and can be composed of one or a plurality of reflection members that can transmit a part of the surface link or plate waves. The reflection configuration constituting the reflection means may be an aggregate of the elements of the reflection configuration (a group of reflection configurations) which are formed as projections, for example, formed of glass, ceramic or metal, and / or grooves in the surface of the propagation medium. In general, the elements of the reflection configuration are formed parallel to each other, and the angle of the reflection member of each of the elements of the reflection configuration, is generally approximately 45 ° for the X axis or the Y axis, with the aim of propagating surface or plate-bond waves in the X-axis and Y-axis directions. As is known from US Pat. No. 5,591,945, which is expressly incorporated herein by reference, may also tilt the elements of the reflection configuration at other angles, to produce non-rectangular wave paths for the screen or to effect a mode conversion between the incident wave and the wave that was reflected, for example, almost Rayleigh, to horizontally polarized shear waves of higher order (S) or Love waves. The elements of the grid can be formed in a common process with the elements of the reflection configuration, for example, screen printing. This common state can reduce the manufacturing cost. The touch screen system according to the present invention typically employs an electronic control system (not shown in the drawings), which generates the acoustic wave of detection and determines the disturbances indicating the position of the contact. The electronic control, in turn, is interconnected with a computer system (not shown in the drawings), for example a personal computer, embedded system, kiosk or user terminal as a human interconnection device. Therefore, the computer system may be of any suitable type and may include, for example, a visual display device, audio input and / or output capability, keyboard, electronic camera, other indication input device, or Similar. The computer system operates using custom software, but more typically, using a standard operating system such as Microsoft Windows (for example, 3.1, 3.11, WFW, CE, NT, 95, 98, etc., or other operating system). which conforms to a set, subset or superset of the Interconnections of the Windows Application Program or APIs), the Macintosh operating system, the UNIX variants, or the like. The touch screen can thus be used as a primary or secondary indicating device for a user's graphic interconnection system to receive the user's input. You can also integrate the touch screen controller and the computer system, for example in an embedded system. A touch-type coordinate input device in accordance with the present invention, can not only be used suitably for a visual display having a curved surface, such as a cathode ray tube, and also a visual display of flat panel , for example, a visual display of liquid crystal and a visual display of plasma.

EXAMPLE 2 The touch screens incorporating the grid transducers were designed, assembled, and tested. Touch screen transducer screens were produced that were fully functional and had production quality signals. _ Only parasitic signals of relatively small amplitude were observed. These parasitic signals were outside the time period of the desired signal for operation of the touch screen. These parasitic signals did not interrupt the operation of the touch screen system and can be further reduced either by time sensitization on the controller electronics or by including the acoustic dampers on the touch screen outside the contact region and the reflection configurations. Despite the significant parasitic wave generation by the grid transducers, the parasitic signals from the reception transducers are not an obstacle to the operation of the acoustic touch screens with grid transducers. The dimensions of the glass substrate were approximately 272.5 millimeters x 348.7 millimeters x 3 millimeters. The glass substrate was provided with a 45 ° bevel on the underside to mount the piezoelectric elements for the TB = 45 ° transducers. This is the normal for the piezoelectric element that forms an angle, TB, of 45 ° with respect to the vertical direction. The 14-millimeter-wide reflection configurations were printed on the glass. The rectangular region of transparent glass within the configurations, has dimensions of approximately 234.6 millimeters x 310.8 millimeters. This provides an active touch area with a diagonal dimension in excess of 15 inches. With the multiple pass printing of the glass frit described above, four grids of approximately 40 microns each were provided at the four locations of the transducer. The wrapped piezoelectric transducer elements 4a, 4b, 10a and 10b were bonded on beveled surfaces 3a, 3b. See Figures 5 and 6. Wire cables (not shown in Figures 5 and 6) were connected in a respective manner, by soldering them to the electrodes of the respective piezoelectric transducers 4a, 4b, 10a and 10b. The wire cables were connected to a controller through a connector. A commercially available ultrasonic type controller (1055E101 manufactured by Touch Panel Systems Co., Ltd., Japan ("TPS")) was used as the controller. A personal computer with the appropriate software was connected to the controller. Adequate performance of the acoustic touch screen was observed. To make comparisons, wedge-transducers were placed temporarily immediately in front of the grid transducers 5a, 5b, 8a, 8b. The grid transducers gave touch screen signals (for signal paths with two transducers) barely 10 dB lower. Although the design and manufacture of the grid transducers were not optimized, the grid transducers showed efficiencies that were really sufficient to be useful for many product designs. In addition, waveforms of the signal were observed. In Figure 7 a representation of a signal is shown from a grid transducer touch screen. The peak that is labeled A is an artifact of the experimental installation. The interference from the burst and the reception circuits result in an attenuated burst signal appearing in the reception signal. This provides a convenient marker of t = 0 in the reception signal. The B label the desired touch screen signal of duration "190 microseconds and start approximately 90 microseconds after peak A. When the touch screen is touched, depression C appears in signal B, as desired for the operation of the touch screen . A small D parasitic signal is observed at approximately 80 microseconds, i.e., 10 microseconds before the desired signal begins. The elimination of this signal was observed by buffering the surfaces, both upper and lower, of the glass substrate near the edge with the two grid transducers. Another small E parasitic signal was observed at approximately 20 microseconds after the desired signal. This parasitic signal is often observed on touch screens with wedge transducers. For the cases of both wedge and grid transducers, this parasitic signal can be eliminated with the appropriate acoustic dampers, which are placed appropriately on the upper surface of the glass (to eliminate reflections from Rayleigh waves on the edges). of glass).

EXAMPLE 3 Figure 8 shows a grating transducer adapted and applied to an acoustic touch screen, which provides a good fit for an acoustic touch screen inside an LCD touch monitor. In Figure 8, a bevel-26, including a seal 24, provides a barrier between the environment and the sensitive operations of the touch screen. The front surface 22 of the substrate 20 rests on the seal 24. The seal 24 is provided to allow sufficient acoustic wave energy to allow operation of the touch screen, while the grid 30 and the piezoelectric transducer 32 are protected, as well as a visual display 28 of pollution flat panel. The piezoelectric element 32 is connected to a rear bevel 38 of the substrate 20, and electrically connected to the weld 34 and a wire 36. The bevel is inclined at a TB angle, with respect to a grid 30 which is placed at along a wave propagation axis in volume that emits the piezoelectric transducer 32 during excitation, or the maximum sensitivity axis of the transducer to acoustic volume waves in the substrate 20. The grid 30 couples a wave in volume that is propagates along an axis of an angle inclined to the grid 30 with a surface bond or plate wave having significant energy at the surface 22. From the perspective of the design of the touch screen monitor LCD, it is seen that the grid transducer provides different benefits that are not obvious from the perspective of the touch screen design alone. The grid has a low profile, typically much lower in height than an optional seal, and fits easily under the bezel. The piezoelectric element, including the welding connections and the associated wire routing, can be adjusted within the volume of the substrate material that was removed, associated with the surface of the bevel of the substrate. In this way, grid transducers facilitate elegant mechanical design solutions for touch LCD monitors.

EXAMPLE 4 Grid transducers, similar to those described in Example 2, were fabricated on a 3-millimeter thick soda-lime glass substrate. These grid transducers had an inclined piezoelectric element (TB = 45 °) with grid elements as shown in Figure 6. The grid was constructed by depositing glass frit ink with the same screen printing processing and used oven cure higher than 400 ° to make the reflection configurations. The high temperature cure sinters the glass frit and bonds it to the glass substrate. The glass frit that was cured is a rigid ceramic material with a density of approximately 5.6 grams per cubic centimeter. Grid heights of up to 40 microns were obtained, using multiple steps of the screen printing process. A grating separation of 0.89 millimeters was designed based on the principles given by Masao Takeuchi and Híroshi Shimizu in "Theoretical analysis of grating couplers for acoustic waves", Journal of the Acoustic Society of Japan, 36 (11): 543-557 ( June 24, 1980). This calculation involved a Rayleigh wave velocity of 3103 meter / second, wave velocity in pressure volume of 5940 meter / second, wave angle in volume of 45 °, and an operating frequency of 5.53 MHz.

Alternatively, suitable reflection elements can also be formed by an ablation process, such as detonation of sand. The piezoelectric element was constructed from a piezoelectric ceramic material of Fuji Ceramics, as is known in the art, and was used in transducers for many touch screen products available with Elo TouchSystems, Fremont CA, and TPS, Tokyo, Japan. This material is in the family of piezoelectric ceramics related to PZT. The piezoelectric elements have a nominal resonance at 5.53 MHz, although the frequency of the design is a matter of choice. The piezoelectric elements are 3 millimeters wide. The piezoelectric element was attached to a beveled surface at an angle of 45 ° with respect to the horizontal surfaces of the substrate. The conductive electrode on the piezo side attached to the glass extended around the piezoelectric element, such that both piezoelectrodes could be welded to the wires on the same exposed surface. An HP 8012B Impulse Generator was used to generate a 5 microsecond gate that was repeated every 5 milliseconds. This gate was used to drive an HP 8111A Function Generator, which in turn generated tone bursts of 5 microseconds in length. The HP 8111A was programmed to generate sinusoidal tone bursts at a frequency .53 MHz with nominal amplitude of 10 Volts. These bursts of tone were seen on a Yokogawa DL12000 4-channel digital oscilloscope, using a 1 MO input channel. These tone bursts were used to excite the grid transducer under test. A wedge transducer was placed on the glass substrate at a distance of 25 centimeters from the grid transducer, and connected to a second 1 MO input channel of the Yokogawa DL12000 4-channel digital oscilloscope. The timing and amplitudes of the transmission burst to the grid transducer, and the signal received from the wedge transducer were simultaneously seen in the digital oscilloscope. In the wedge transducer a signal was observed from the grid transducer, demonstrating the successful emission of a wave having appreciable surface energy from the grid transducer. The placement of a finger or other Rayleigh wave absorber between the grid transducer and the wedge transducer eliminated the received signal. This shows that the received signal is due to the propagation of the Rayleigh wave between the grid transducer and the wedge transducer, as would have been expected that the wave modes with substantial subsurface energy demonstrate a lower degree of attenuation, and in this substrate and this broadcast frequency, the only way of reasonably probable wave observed is an almost Rayleigh wave. In addition, the time delay between the burst of tone and the received signal corresponds correctly to the known Rayleigh wave velocity in the glass substrate.

EXAMPLE 5 Examples 1, 2 and 4 employ transducers with an emission (or reception) angle of 0o. That is, the direction of the Rayleigh wave is the same as the projection of the propagation axis of the wave in volume in the horizontal plane. The design of the grid transducer is not so limited. The concept of the grid transducer can be generalized to the case in which the direction of propagation of the Rayleigh wave has a non-zero emission angle, TE, with respect to the horizontal component of the direction of the wave in volume. Non-zero emission angles have the following two potential advantages. Non-zero emission angles add mechanical design flexibility. See Figure 9, which shows a plan view of a pair of receiver grating transducers at a corner 58 of a touch screen 66. Each grid transducer includes a piezoelectric element 60a, 60b, mounted on a rear beveled surface 56, with a set of grid elements aligned across the substrate 66, along a volume wave-coupled axis 52a, 52b of the piezoelectric transducer. The grids 54a, 54b are inclined with respect to the axis of the propagation 52a, 52b of the wave in volume, such that the wave in volume is converted to a wave mode that is attached to a single surface or a plate wave which travels along an axis 50a, 50b, different from the axis of wave propagation in volume, traveling parallel to the edges 64, 62 of the substrate 66, respectively. This design is convenient if, for example, there is a mechanical interference between the nominal corner of the glass substrate and another component of a touch monitor, such as a mounting post. A second benefit of a non-zero emission angle is an angular separation of the emission angle of the desired Rayleigh wave and the zero emission angle, typical of the parasitic volume waves, generated by the piezoelectric element. Equivalently, as indicated in Figure 9, there is an angular separation of the sensitivity direction of a receiving grating transducer, and its sensitivity direction to the parasitic volume waves that enter. It is noted that the wave in volume, coupled with the piezoelectric transducer, can have an arbitrary angle with respect to the Rayleigh wave, for example 90 °, allowing possibilities for spatial separation of the desired Rayleigh wave and parasitic waves traveling parallel to the horizontal projection of the wave propagation axis in volume. Therefore, a system having an inclined piezoelectric element (TB = 45 °), and a grid transducer with a non-zero emission angle (TE = 30 °) was constructed. The manufacturing methods were the same as for the zero emission angle mode of Example 4. The only difference was that the spacing and orientation of the grid were modified to conform to the horizontal components of the Bragg scattering condition, to couple the wave vector of the Rayleigh wave to the horizontal component of the pressure wave in volume. These grid transducers with 30 ° emission angle were tested, using the same experimental methods described in the zero emission angle mode of Example 4. The quantitative data of time delay and sensitivity to surface absorbers confirmed that this It was a Rayleigh wave signal. In this way, the operation of a grid transducer with non-zero emission angle has been clearly demonstrated. The directivity of the grid transducer with nominal emission angle of 30 ° (0B = 45 °) was measured by placing a reception wedge transducer at different locations in a circular arc, at a radius of 250 millimeters from the grid transducer. The following table shows the relative amplitude of the measured signal (relative to the maximum observed amplitude) transmitted through the pair of transducers, as a function of the emission angle.

It was observed that the grid transducer has a directed beam transmitted at a non-zero emission angle. The peak observed at the emission angle of 31.5 ° is close to the nominal design value of 30 °. In this way, it is seen that a grid transducer can support non-zero emission angles, providing new important options for the design of acoustic touch screens.

EXAMPLE 6 As indicated in Figure 10, an option is the special case of a piezoelectric element 32 mounted horizontally, that is, TB = 0 °. Note that this grid transducer design avoids the need for a machined bevel surface on the edge 68 of the substrate. This absent manufacturing process has the potential to reduce the manufacturing cost. As shown in Figure 10, the wave 72 in volume is partially reflected off the front surface 22, next to the gratings 30, producing a converted wave mode 79, which is a Rayleigh wave. A portion of the wave energy is converted to a wave traveling parallel to the surface 22. Typically, the back surface 42 of the substrate 20 has low acoustic energy coupled to a received wave, and is therefore insensitive to touch, allowing the mounting on the rear surface. They designed, assembled, and tested touch screens that incorporated grid transducers in which TB = 0 °. The methods that were used were the same as in Example 2, except that the glass substrate was not provided with a bevel. Again, resulting grating transducer touch screens were produced, which were fully functional and had production quality signals. - Again, the generation of parasitic waves did not prevent the successful operation of transducer acoustic touch screens grid, and the observed parasitic signals were minimal. To make comparisons, wedge transducers were placed temporarily, immediately in front of the grid transducers. For this case where TB = 0 °, the grid transducers and the wedge transducers gave the same touch screen signal amplitudes within the experimental errors. Although the design and manufacture of the grid transducer were not optimized for the grid transducers where TB = 0 °, the efficiencies of the transducer of commercial interest have been clearly demonstrated. Note that an approximately 10 dB (5 dB per transducer) signal increase was observed, relative to the grid transducer where T = 45 ° of Example 2. This experimental observation suggests that the new physical effects can lead to improved efficiencies for the designs of grid transducers in which TB = 0 °.

EXAMPLE 7 Grid transducers, similar to those described in Example 6, were fabricated on a 3-millimeter thick soda-lime glass substrate having grid transducers in which TB = 0 °. Measurements were made using the same manufacturing techniques and test methods described in Example 4, except that the glass was not beveled, and the element piezoelectric was mounted opposite the grid on the bottom surface of the glass, as shown in Figure 10. An increased efficiency was observed in relation to the grid transducers where TB = 45 °. This confirms that the increased signal amplitude of the touch screen of Example 6, relative to the touch screen of Example 2, is in fact due to an improvement in the efficiency of the grid transducer for TB = 0 °. In the case where TB = 0 °, new mechanisms or physical effects come into play, not present in cases where TB is different from 0 °. The wave in vertical volume can support multiple reflections on the upper and lower substrate surfaces, and still have the correct orientation and phase to couple to the piezoelectric element and Rayleigh waves through the grid. These multiple reflections provide means to improve the efficiency of the grid transducer, by providing the wave in volume more than one opportunity, to be coupled by the grids to the desired acoustic mode. Another way to see if = 0 'is to consider the thickness resonances of the substrate. Both the grid and the piezoelectric element are coupled to the thickness oscillations of the substrate. A preferred means of obtaining this resonant condition is to place the piezoelectric transducer on a surface parallel with the surface of the grid transducer. Although it is equivalent to the conceptual model of multiple reflections described above, the thickness oscillation structure considers this effect in the frequency domain instead of the time domain. It is therefore of interest to consider what happens when the frequency of operation corresponds to a thickness resonance of the substrate. By means of tuning the thickness of the substrate and / or frequency of operation, the thickness resonance can be reinforced. This provides additional elements to improve the efficiency of the transducer. The thickness mode resonance or the multiple reflections of the vertical volume waves can be used to increase the mesh coupling between, for example, vertical pressure waves and, for example, Rayleigh waves. This in turn reduces the optimal height of the grid for maximum efficiency of the transducer, and consequently simplifies the manufacturing process. The thickness mode resonance also provides design freedom to tune the resistance of the equivalent circuit of the piezoelectric element together, and consequently controls the electronic impedance characteristic of the acoustic touch screen. Figure 11 shows an equivalent circuit for a grid transducer. These oscillations or multiple reflections alter the impedance mechanical or acoustic of, for example, glass surface to which the piezoelectric element is attached. In a thickness resonance, the acoustic impedance of the glass is reduced, and the mechanical Q of the piezo attached to the glass is increased. This has the consequence that the resistance ("R" in the circuit diagram of Figure 11) of the equivalent circuit of the transducer is reduced. If the piezo is properly tuned to the operating frequency, that is, l /. { 27iV '(LC1)} is equal to the operating frequency, then the impedances of the resonant inductance and capacitance are canceled, and the equivalent circuit is simply the capacitance C0 in parallel with the resistance R. The energy sent to the piezo is given by V / R, in where V is the square root of the average applied impulse voltage. The transducer burst circuitry system of the commonly known commercial touch screen controllers is closer to a voltage source than a current source. This is particularly true if the amplitude of the burst of transmission is limited by maximum voltage safety criteria (eg, from Underwriter Laboratories). Assuming a fixed voltage for an excitation signal, a transducer resistance of the smallest equivalent circuit means electrical power increased sent to the transducer. Consequently, with some controller designs, the thickness resonance can significantly increase the electrical energy available to convert the acoustic waves.

EXAMPLE 8 Grid transducers were manufactured and successfully tested on aluminum substrates. Aluminum can be used as a substrate for opaque touch panels. This illustrates that the principles of grid transducer operation are not limited to a particular selection of substrate materials. A grid was formed by machining slots on the surface of the aluminum substrate. The grills were designed to be grooves 51 microns deep, 254 microns broad, and 533 micras separation center-to-center. The grid had 10 grills. As in Example 6, using a glass substrate the piezoelectric element was mounted horizontally, and the emission angle is zero. In this case, the thickness of the aluminum substrate in the region of the grid was designed to correspond to a thickness resonance. The thickness of the substrate was 2.29 mm in the region of the grid. The operation of the grid transducer was observed, using tests similar to those described in Example 4.

A tone burst of 3 to 4 microseconds, with a peak-to-peak amplitude of 14 Volts, was used as a transmission pulse to excite a wedge transducer. The Rayleigh wave from the wedge transducer was directed into the grid. In the lower part of the substrate, a 2-millimeter-wide piezo was mounted below the beginning of the grid. A received signal was observed with a peak amplitude of 1.4 Volts peak-to-peak, i.e., -20 dB with respect to the excitation signal. The signal amplitude for a pair of wedge transducers gave a similar measured signal. Note the successful construction of a grid transducer using slots instead of material deposited on the substrate. This also demonstrates a variety of manufacturing processes for the manufacture of the grid.

EXAMPLE 9 Piezo grid transducers were manufactured with a non-zero emission angle (45 'prototype), with three different grid materials, including two materials that are not characterized as glasses. Rayleigh, cured glass frit (approximately 10 μ in height), epoxy loaded with Lithopone ™ (approximately 25 μ in height), and tungsten-laden epoxy (approximately 25 μ in height) .The epoxy thus provides a polymer matrix for an inorganic filler composition. The mass deposited for the glass frit and epoxy filled grids of Lithopone ™ were approximately the same, and the corresponding received signals were the same within the experimental uncertainties. The epoxy grids loaded with tungsten had two to three times the mass, and had a corresponding increase in the amplitude of the received signal. The use of polymer grid materials provides increased design and process flexibility.

EXAMPLE 10 In Examples 2, 4, 5, 6 and 7, the volume wave coupled to the piezoelectric element is a pressure wave. For example, the elements 4a, 4b, 10a, and 10b shown in Figures 5 and 6 are piezoelectric elements optionally in shear mode. However, as demonstrated in the present embodiment, a shear wave volume can be generated by using the more conventional piezoelectric element of pressure mode, and of lower cost. This embodiment is implemented by the use of a piezoelectric element 32 of compression mode, assembled non-conventionally, as shown in Figure 12, in such a way that wave 78 in volume is converted to a shear wave 80, with movement of particles in the plane of paper, before it reaches the grid 30. In Figure 12, the substrate 20 is soda-lime glass, with a pressure wave velocity in volume of 6000 meters per second, and a shear wave velocity in volume of 3433 meters per second. The piezoelectric element 32 of compression mode of 5.5 MHz is tilted with respect to the horizontal by an angle? = 62.6 °. The pressure wave 78 in emitted volume propagates in a downward direction, at an angle f? P with respect to the vertical direction. This leads to a wave 80 of shear stress reflected upward, which propagates at an angle TB = 30.5 ° with respect to the vertical direction. The value of? A is determined by Snell's Law: sin (? S) / Vs = sin (0p) / Vp. The value of f? P in this example is selected to satisfy an acoustic analog of the Brewster angle of optics. As can be calculated using known acoustic principles, for example, see Equation 9.45 (FII = ...), B.A. Auld, Acoustics Fields and Waves in Solids, (second edition) Volume II, Krieger Publishing Co., Malabar, FL, 1990, ISBN 089874783-X, the incident pressure wave is reflected at 100 percent as a shear wave. This mode conversion reflection enables the efficient generation of shear wave volume, with a piezoelectric element of common pressure mode. The ability to illuminate grid 30 with a wave 80 of shear stress even with a piezoelectric element of pressure mode, provides an interesting option to alter or optimize the "F" factor for, for example, Rayleigh wave generation (see Takeuchi et al., 1980). This case, which is shown in Figure 12, provides a particular benefit when the substrate shown is a top laminate 20 of a lamination 20, 130, 132 of security glass, ie the glass 20, 132 of soda. lime by sandwiching polyvinyl butyrate polymer 130, or other laminate. In this case, the shear wave is reflected off the back surface 42 of the upper glass sheet 20, and because of the large difference in acoustic impedance between the glass 20 and the polyvinyl butyrate 130, most of the the wave 80 will still be reflected upwards towards the grid 30, and it will be converted to, for example, a Rayleigh 79 wave. On the other hand, parasitic plate wave modes will be rapidly attenuated by layer 130 of the polymer. The bevel 74 on the upper side of the upper laminate 20 of the safety glass lamination is easily accessible for, for example, a robotic piezoelectric element process, and furthermore eliminates the mechanical interference between the piezoelectric element 32 and any polymer 130 in excess that extends beyond the glass sheet that forms the substrate 20.

For this specific example, with? A = 30.5 °, the shear stress wave has a sin2 fraction (0s) or about 26 percent of its energy in the form of shear motion in the vertical direction, and a fraction cos (0s) or approximately 74 percent of its energy in the form of horizontally polarized shear movement. As illustrated in a later example, this large horizontal shear component makes possible embodiments in which the wave emitted from the grid is a horizontally polarized shear wave, such as a Love wave or a HOHPS wave.

EXAMPLE 11 Grid transducers can be designed in which the acoustic mode transmitted (or received) is not a Rayleigh wave. Figures 13A and 13B consider grid transducers that use a piezoelectric element 32 'in a horizontal shear mode that excites a horizontally polarized shear wave, namely, a Love 94 wave. The substrate 84, 86 in layers is, for example, a layer of 0.5 millimeters thickness of glass with a low shear rate in volume, such as Schott B270MR glass, a glass containing barium, attached to a layer of 3 millimeters soda-lime glass. That substrate 84, 86 can propagate a wave 94 of Love, which provides a higher energy density of horizontal shear movement at surface 82, than that which provides a lower order polarized shear stress wave (ZOHPS), on a 1 mm glass substrate thick. The shear stress of the piezoelectric element 32, the shear stress of shear wave volume 92, the axes of the grills 90, and the shear force motion of Love's wave 94 are all perpendicular to the shear force. plane of the paper in Figure 13A. Figure 13B, on the other hand, employs a geometry similar to that shown in Figure 12. However, in this case, the shear wave 96 in horizontally polarized volume, from the stress-shaped piezoelectric element 32 ' horizontal cutting is simply reflected off the back surface of the substrate 86, without any conversion mode, and consequently the angle of incidence equals the reflectance angle. These grid transducers can be designed with the variations of the piezo orientation and the emission angle described above. However, for large emission angles, for example 90 °, as an example of the worst case, efficiency is lost since the horizontal shear stress of the wave in volume is no longer parallel to the horizontal movement of the emitted wave.

The spacing and orientation of the grid is determined by the Bragg scattering condition between the wave vector of the Love wave emitted, and the horizontal component of the wave vector of the wave in volume.

EXAMPLE 12 As shown in Figure 14A, focus grid transducers can be constructed by providing curvature to the grills 5a ', 5b', 8a '. Note that there is no need for a curved piezoelectric element. Without any manufacturing cost added to the piezoelectric element, the grid transducers provide freedom to adjust the focusing characteristics of the emitted acoustic beams. This is not the case for wedge transducers or shore transducers. For a grid transducer with a horizontally oriented piezoelectric element, the radius of curvature of the grills 5a ', 5b', 8a 'is set equal to the desired focal length 100, 102, 104. The effective focal length is preferably about half to three quarters of the length of the directional directional antenna 6a, 6b, 7a, although the focal length may also be equal to or longer than the directional reflection antennas. These elements of the grid can also be parabolic or of another desired configuration to direct the energy of the wave acoustics along a desired path. Typically, the desired focal length of the grid is long compared to the grid dimensions, and the parabolic curvature and circular curvature are practical equivalents. For a grid transducer with an inclined piezoelectric element, there is equal freedom to adjust the focal length, although the governing mathematical equations are more complex. The principles of the Bragg dispersal are still applicable. The desired Bragg scattering angle becomes a function of the position inside the grid transducer. The curvature of the grids of the focus beam transducers can be designed with the help of Figure 14B and the following equations: dy / dx = tan (tr / 2 - 0g) = [/ cRsen? R] + KR / íjSenc / íjjCOSf sin (0g -?) = [? Bsen? B sen? ] /? g. A light focus of the transducer beams can be used to partially offset the signal loss of the diffraction beam distribution. For example, the focal length of the focus grid transducer can be set to have the length, or half the length, of the directional reflection antenna. As shown in Figure 14A, it does not show the directional reflection antennas, but can encompass both the Adler type touch screen, or the Johnson-Freyberger type touch screen of the U.S. Patent Number 3,673,327, the grids may have a focal point, which is preferably approximately one-half to three-fourths the distance across the substrate.

EXAMPLE 13 Figure 15A considers the design of a grid transducer in which the factor F can be one, and consequently for which the efficiency of the transducer is further improved; see Takeuchi et al. (1980). This is possible with a shear wave volume wave, incident on the grid with a sufficiently negative value for TB that satisfies the following equation: | sin (0B) | > Vs / Vp = (0.5 - s) / (l - s) 1/2 where Vs is the shear velocity in volume, Vp is the pressure wave velocity in volume, and s is the Poisson ratio. When this condition is met, and the spacing of the grid is designed to couple the shear waves in volume, and the Rayleigh waves, there is no coupling of the Rayleigh waves to the pressure waves in volume, by dispersion of Bragg. For aluminum with a Poisson ratio s = 0.355, the previous condition is evaluated numerically as 28.3 ° Consequently, a grid transducer with F = 1 can be constructed with a piezoelectric shear element horizontal, mounted on a substrate surface inclined in the direction indicated by Figure 15A at, for example, 30 °. In this way, as shown in Figure 15A, the piezoelectric transducer 32 is established to produce a wave 108 in volume having a projection of a propagation axis in the plane of the opposite grid 30 ', from the axis of propagation of the mode 79 of the converted wave. The piezoelectric element 32 is protected inside an internal bevel, allowing the protrusion of the weld 34, the connecting wire 36 and the signal cable 106 to be protected. In some cases, as shown in Figure 15A, it may be convenient for the piezo, solder connections, and wire routing to be protected by placing them inside a concave indentation within the substrate. In some cases, these advantages of mechanical design will justify the geometry of Figure 15A, even if F < 1 because, for example, a piezoelectric element of lower cost pressure mode is used. Particularly for the polymer substrates formed by a molding process, the geometry of the substrate of Figure 15A can provide with little added manufacturing cost, the benefits of F = l and the mechanical protection of the piezoelectric element. For example, for Styron® 666 (polystyrene from Dow Chemical), the Poisson ratio s = 0.35, and again a piezo of shear mode negatively inclined by approximately 30 ° or more, provides F = l. The polymer substrate modality of the Rayleigh or Love wave grating transducers of the geometry of Figure 15A are of particular interest because, as noted above, wedge transducers are difficult or impossible to design for substrates of polymer. Note that for molded polymer substrates, the grid (and the directional reflection antennas) can be designed inside the mold. In this process, it is not difficult to support grids with a variable height or depth. An alternative embodiment, as shown in Figure 15B, combines the principles of Figure 15A and Figure 12. For example, for a polystyrene substrate 20, the piezoelectric element 32 can be mounted at an angle of 60 ° with respect to the horizontal The piezoelectric element 32 is coupled to a volume pressure wave 116, which propagates at 60 ° with respect to the vertical, directed towards the grid 30 '. In the reflection surface 112, this pressure wave in volume is reflected by 90 ° and is converted in the mode to a wave 118 of shear stress in volume with _i -30 'The reflection surface 112 makes an angle of 55.6 ° with respect to the vertical. The acoustic principles that are given in the textbook of B.A. Auld, referred to in the Example 10, results in a mode conversion efficiency of 77 percent on a reflection surface. Figure 15B further demonstrates the possibility of mounting the piezoelectric transducer 32 in a wedge structure 110, which may be attached with adhesive or other means at an interface 120 to the substrate 20. The interface 120 does not attenuate the wave 118 mode in volume to no great degree. Therefore, the substrate 20 does not need to have surface structures made on both sides 22, 42. Figure 15B illustrates an example in which the wave is reflected in volume, and perhaps the mode converted by a reflection surface. It is also possible to include two or more wave reflections in volume in designs of grid transducers. This adds more options to grid transducer designs for acoustic touch screens. Absorbers placed in the vicinity of the grid transducer structure can be used to suppress the effects of parasitic waves. The ability to mold reference surfaces and / or to apply matching acoustic impedance absorbers provides much flexibility in the direction of parasitic waves.

EXAMPLE 14 For TB other than 0 °, the grid transducers are unidirectional, that is, they preferentially emit a beam in the forward direction, and not in the rear direction. For TB = 0 °, the symmetrically designed grid transducers are bidirectional, that is, they emit (or receive) equally in the front and rear directions. In some cases, it may be convenient if the touch screen grid transducer is designed to be coupled to two useful wave modes that propagate antiparallel to each other. It is possible to design a unidirectional grid transducer of TB = 0 °. One approach is to place an acoustic reflector behind the grid transducer. As shown in Figure 16, for example, can a grid with a medium wavelength (n + 1/2) be placed? 122 behind the grid 30 to convert the wave modes. In the embodiment shown in Figure 17, the reflector 128 is simply an extension of the grid spaced apart by wavelength (n?) In the backward direction. A grid 128 spaced by wavelength couples the back acoustic wave 126 to the vertical volume waves 130, which are reflected off the back surface 43 of the substrate, and then coupled to the desired front acoustic waves 124 in the extension of the grid 128. The front wave 124 and the rear wave 126 are added as an effective wave 79, emitted from the transducer system. Alternatively, as shown in the Figure 18A, for the generation and reception of the Rayleigh wave, an asymmetric grid form 132 can be employed. In an article of May 1, 1969, from Electronics Letter (Volume 5, Number 9), incorporated herein by reference, experimental evidence is provided that such a grid may be unidirectional. Theoretically, the interaction of the wave in vertical volume with the asymmetric grid can lead to the elliptical movement of particles. Since the Rayleigh waves moving in opposite directions correspond to the elliptical movement of particles in opposite directions, the excited grid will elliptically be coupled to the Rayleigh waves of one direction. Professor Takeuchi and Professor Yamanouchi, "Unidirectional excitation of piano waves in a periodic structure", October 1991, incorporated herein by reference, shows that a periodic directional antenna of excitation centers out of phase in an eighth wavelength ( n + 1/8)? of a periodic directional antenna of scattering centers, can lead to the unidirectional emission of acoustic waves. Similar principles, according to the present invention, can be applied to a grid transducer of a touch screen. Surface-guided waves, such as Rayleigh or Love waves, penetrate to some degree within the substrate; there is still substantial energy density, for example, half wavelength below the surface. In accordance with one embodiment of the present invention, which is shown in Figure 18B, the elements of the diffraction acoustic wave coupler 90 ', 90"can also extend a similar depth below the upper surface. The wave 92 'in volume of the piezoelectric transducer 32', which in this case is a piezoelectric element in shear mode, acoustically coupled to the lower part of the substrate 88 ', which approaches the front surface 82 of the substrate 20' , it will reach the region 86 'that is located more deeply, before it reaches the shallow 84' region. The substrate 20 'is formed as a laminate capable of supporting the Love wave propagation. To allow this time delay and the corresponding phase change, the elements of the diffraction acoustic wave coupler 90 ', 90"may have a relative offset 91, or be inclined, to achieve the constructive interference for the desired direction of propagation of Love's 94 'wave along the surface, with energy comparatively greater than a 94"wave propagating in an opposite direction. This type of coupler, therefore, can be made partially or completely unidirectional. In this case, the substrate can be, for example, aluminum coated with a dense layer of an enamel containing heavy metal. The elements 90 'of the buried diffraction acoustic wave mode coupler, are %% 8 can form as a stamped impression on the surface of the aluminum, which is filled with the enamel 84 'during the coating, and the elements 90"of the surface-diffractive acoustic wave mode coupler can be printed on the enamel 84 ', before it is completely cured. The relative phase shift 91 is established by a mechanical accessory that is not shown.

EXAMPLE 15 Acoustic detectors employing grid transducers need not be limited to configurations limited to four transducers in total. As is possible with acoustic touch screens employing wedge transducers, designs with six, eight, or more transducers can be provided in a single system or touch detector substrate, in accordance with the present invention. For example, in one embodiment of a rectangular touch screen, in accordance with the present invention, two grid transducers are provided at each corner, with four detector signals acquired for processing by the controller electronics, to determine the tactile position: X right; X left; And superior; and And inferior. This can be generalized-more by, for example, measuring the X-coordinate by three or more pairs of directional antennas. However, the modalities of acoustic touch screen are of particular interest of grid transducer that do not have wedge transducer touch screen analogues. Note that grid transducers, like wedge transducers and unlike shore transducers, can be placed anywhere on the surface of the substrate, regardless of proximity to a free edge. However, unlike wedge transducers attached on the surface of the substrate, the grid transducers need not present any obstruction completely acoustically opaque when placed in a useful acoustic path of another detector subsystem. Grid transducers enable greater design freedom to overlap the detector subsystems. In particular, the grid transducers enable the seamless lining of the detector subsystems, as shown in Figures 19A and 19B. Figure 19A shows a pair of grills of a transmission grid transducer 142 and reception 140, as well as the corresponding directional transmitting reflection 146 and reception 144 antennas. These grills and directional reflecting antennas can be formed in many ways, for example, printing, acid corrosion, stamping a metal substrate, or shaping the mold for a polymer substrate. In a preferred embodiment, the grids 140, 142 are part of unidirectional transducers, for example, are placed a wedge made of, for example, the same material as the substrate material, between the piezoelectric element and the back of the substrate, in a configuration similar to that shown in Figure 15B, such that < 9B < 0 °. Figure 19B shows a possible pairing configuration of grid pairs 150X, 152X, 150Y, 152Y, and 154X, 156X, 154Y, 156Y directional reflection antennas. The filled circles represent the transmission grid 150X, 150Y transducers as in Figure 19A, the thick arrows represent the directional transmitting reflection antennas 154X, 154Y, the thin arrows represent the directional reception 156X, 156Y antennas, and the open circles represent the 152X, 152Y grating transducers. Alternatively, the directional transmit and receive antennas are superimposed and are associated with a single common transmit / receive grid transducer (not shown in the drawings). As indicated by the dotted arrow in Figure 19B, directional antennas 154X of transmission in X, direct the acoustic waves downwards. In a similar manner, Y-transmit directional antennas 154Y direct acoustic waves to the right. Note that each point on the surface is detected by at least one detector subsystem in X, and at least one detector subsystem In Y. For most of the tactile surface, there are in fact two measurements of X and Y. This tiling can support a touch surface of arbitrary size. For touch 160, the Y coordinate is detected by a 158Y wave. The X coordinate is detected by the 158X and 158X 'waves. In the embodiment of Figure 19B, it may be desirable to use gratings (and directional reflecting antennas) with reduced coupling strength. Although this will reduce the amplitudes of the signals, and consequently will reduce the maximum size of the individual detector subsystems, this will beneficially reduce the shading of the acoustic signals of the components of other superimposed detector subsystems. In addition, it may be useful to leave desired acoustic trajectories deviating from the orthogonal X and Y directions, such that, for example, the X-directional directional antennas produce less than one localized shadow for the Y-detector subsystems. preferred, Rayleigh waves are used to detect touch. For example, the touch surface may be the aluminum or steel hull of a robotic device, which does not need to be flat. That touch-sensitive robot surface can be used, for example, to avoid collisions. Optionally, the metal touch surface can be provided with a plastic cover sheet that is designed to make intimate acoustic contact only when a force presses the plastic against the surface tactile In another preferred embodiment, Love waves are used to detect the touches. A Love wave substrate can be provided, for example, by aluminum coated with a dense enamel. In this case, the grid transducers and the directional reflection antennas are provided as grooves or acid corrosions on the aluminum surface, or as an applied material protruding into the enamel. This embodiment is of interest for, for example, large white board applications, where reduced sensitivity to liquid contaminants is desired, such as the ink drying solvents of the down.

EXAMPLE 16 As described in Example 10, the pressure wave mode piezoelectric element of Figure 12 can be used, combined with a reflection off the back surface of the substrate, to be coupled to a shear wave volume wave. The present embodiment shows that, unlike the pressure wave in volume, a shear-force wave in volume can be used to couple to a Love wave. This embodiment includes a Love wave substrate 196, for example, as shown in Figure 13B. Figure 20, which shows a pair of receivers, illustrates a preferred embodiment in which Love waves 210, 212 are excited, with emission angles of 90 ° in the plane of the grids, with respect to the propagation axis of the waves 214, 216 in volume, which in turn are reflected out of the back surface of the substrate, and are coupled as volume waves in pressure mode, with the piezoelectric transducers 198, 200 mounted to the front bezel 204, 206. For a 90 ° emission / reception angle, the grids 202, 208 are not perpendicular to the propagation axis 210, 2132 of the Love wave, but rather rotate at an angle? G satisfying the following equation tan (0g) ) / Vlove = sin (? S) / Vs The Vlove velocity of the Love wave, calculated on the basis of the known properties of the laminated materials, can be determined empirically, or the angle can be changed experimentally, to find the angle of maximum efficiency, which, in turn, allows the determination of the effective phase velocity of the Love wave. Since the wave velocities of the Love wave and the shear stress wave in volume are not so different, and the angles are relatively small, the optimal value of? G will not be too far away from TB. It is noted that the emission / reception angle does not need to be 90 °. However, at angles other than 90 °, some loss of efficiency is expected. The horizontal component of the shear force movement of the wave in Volume will no longer be parallel to the shear force motion of the Love wave. For example, for a 45 ° emission angle, a loss by a factor of 2 is expected in efficiency. This Love wave grid transducer design is simple and compact. This does not add manufacturing steps, nor additional parts, compared to a single inclined piezo grating transducer, and has the virtue of avoiding the need for a more costly piezoelectric element.

EXAMPLE 17 There are a number of designs of acoustic touch screen systems that operate without a directional reflection antenna. See, for example, U.S. Patent Number 3,673,327, to Johnson and Freyberger (1972), and PCT Application WO 94/02911 (PCT / JP93 / 01028, 1994) to Kohji Toda, both incorporated herein by reference. as a reference in its entirety. The grid transducers enable novel variations of these acoustic touch screens. Figure 21, which is analogous to Figures 16 and 19 of WO 94/02911, represents a design in accordance with the present invention, in which the "T" s are the transmission grid transducers, and the "R" "s are the reception grid transducers. In accordance with a preferred embodiment of the present invention, these grid transducers of the Figure 21 comprise a sheet of polyvinylidene fluoride ("PVDF") in which a metallization pattern is formed, which defines a plurality of piezoelectric elements. This sub-assembly of polyvinylidene fluoride is then mounted on a beveled surface of the substrate, to produce waves in volume that propagate to respective grid elements. When polyvinylidene fluoride is used, it may be convenient to employ a local impedance matching circuit to the transducer, for example, a field effect transistor ("FET"), to allow the use of lower impedance wiring, with interdigital transducers. relatively higher impedance polyvinylidene fluoride. In comparison with the interdigital piezoelectric elements attached to the upper surface of a glass substrate, according to the prior art, the gratings on the upper surface and the piezoelectric element acoustic transducers on the lower surface (i.e., grid transducers) , in accordance with the present invention, provide the following benefits: (a) simpler piezoelectrode designs, for example, without the need for 1/4 electrode line amplitudes; (b) the relative angular alignment of the transducers is more easily provided with a one-step printing of the grids; and (c) delicate piezoelectric elements and electrical connections moved to the substrate surface away from the user . Figure 22 shows a grid transducer having a relatively simple structure, and yet coupled to two different wave modes, for example, a Love 162 wave and a Rayleigh 164 wave. The substrate 84, 86 supports the propagation of Love waves, as well as of Rayleigh waves. For example, the upper piezoelectric element 174 may be a pressure mode piezoelectric element that is coupled to the Rayleigh waves 164 by the pressure volume wave of? = TB = 60 °, mounted on the surface 178 of the bevel, and the lower piezoelectric element 172 can be a horizontally polarized shear force piezoelectric element, which is coupled to the shear waves 168 in volume by volume wave Shear stress = 24 °, mounted on the surface 176 of the bevel. The spacing of grid 166 can be calculated using the Bragg scattering principles described above, to couple both the Rayleigh wave with a pressure wave in volume at TB = 60 °, and the Love wave at a shear stress wave in volume a? s = 24 °, in a way that provides multiple peaks useful in its two-dimensional Fourier transformation. You can calculate the TB angle of propagation of the shear stress wave in volume, from the Love wave phase velocity, the grid spacing, and the stress velocity cutting in volume. For aluminum (s = 0.355) and to the extent that the Love wave velocity is similar to the Rayleigh wave velocity, TB is approximately 24 ° for the shear stress wave in volume. That detector can easily distinguish, for example, a finger touch of a drop of water by the ratio of the wave absorption of Love to Rayleigh wave. In another embodiment, which is also exemplified by Figure 22, a double-mode grating transducer is provided, which is sensitive to the Love wave of zero order and the Love wave of n = 1. In this case, both elements 172, 174 piezoelectric are horizontally polarized shear mode piezoelectric elements, and the substrate 84, 86 has a layer 84 of slower upper shear rate that is sufficiently thick to support the propagation of Love waves of zero and first order. By preferentially absorbing the shear energy at the surface, a touch can change the depth profile of the energy in shear mode, and consequently converts some of the incident energy, for example, love wave 162 zero to, for example, 164 wave energy of Love of the first order. By transmitting a Love wave 162 of n = 0, and receiving a Love 164 wave of n = 1, or a Love wave of both n = 0 162 and n = 164, a tactile signal is obtained positive, or a detector system positive and mitigating response. If only the positive touch signal is desired, then the grid transducers can be designed for the desired modes, with individual piezoelectric elements. The grid transducers thus provide options for the choice of acoustic modes on acoustic touch screens.

EXAMPLE 18 The acoustic source need not be a simple piezoelectric element with simple upper and lower electrodes. In accordance with the present example, more complex acoustic sources are considered. These can include multiple piezoelectric elements and / or piezoelectric elements having complex electrode configurations, as shown in Figure 23. In the case of relatively thick substrates, for example, a glass substrate 180 of 12 millimeters thick, could be preferable to mount the piezoelectric element 188 on a vertical edge 192, near the grid 182, instead of the lower surface 194, which is relatively far from the grid 182. The location of this closest piezoelectric element 188 will help to minimize the expansion of diffraction of wave 184 in volume, emitted from piezoelectric element 188. In a preferred embodiment, the element 188 piezoelectric has a floating lower electrode 190, and an exposed array of electrodes 192, 194 that is interdigital in geometry. The spacing, s, of center-to-center of the surrounding interdigital electrodes 192, 194 corresponds to half the wavelength of the wave in volume in the substrate, divided by the cosine of the angle TB of wave 184 by volume desired, with respect to the vertical direction, that is, s = l / 2 *? (volume) / eos (0B). Note that all interdigital electrodes 192, 194 are maintained at a common voltage during clustering, but during operation they are connected with alternating polarities as indicated. A loss of efficiency of 3 dB is expected in the design shown in Figure 23, compared to the design shown in Figure 1, because the piezoelectric element 188 will generate waves in propagation volume both upwards 184 and down 186. Alternatively, with a sufficiently small spacing of the interdigital electrodes, and electronics that can control the individual phase adjustment of the signals to, or from each electrode, such that the adjacent electrodes do not need to be of alternating phase, wave 186 can be eliminated in downward propagation volume.

EXAMPLE 19 As is known in the prior art, it can be used a pair of grids appropriately arranged and constructed on a substrate, for transferring the wave energy from a first surface of a substrate to a second surface of a substrate. See, Humphryes and Ash (1969), incorporated herein by reference in its entirety. In this way, this structure can be considered a "way". In accordance with the present invention, that structure allows the use of any structure, including a wedge transducer or grid transducer, to generate a wave having a surface energy on a first surface of the substrate, which can then be efficiently transferred to a second surface of the substrate, thereby removing the structures that generate the acoustic wave, to a surface of the substrate separated to the directional reflecting antennas or the touch surface. That configuration also allows an acoustic wave to pass a normally obstructive or interfering structure. Figures 24A, 24B and 24C illustrate one embodiment that uses these acoustic pathways as a means to provide a tactile surface 238, arbitrarily located on the surface 242 of a larger uninterrupted substrate. The substrate 246 may be, for example, a tempered soda-lime glass sheet 6 millimeters thick, which is large enough to serve as a table or counter-table. The design engineer can locate the zone 238 arbitrarily sensitive to the touch inside the uninterrupted upper surface 242 of the substrate. On the front surface 242 only four elongated arrays of grids 240 appear. In a preferred embodiment, these grids are slots that are filled with a clear epoxy such that there is no interruption of the flat surface 242 of the upper substrate. In particular, note that there are no directional reflection antennas or transducer components on the surface of the upper substrate. Behind the touch-sensitive area, a visual display device in a joining region 236, with a suitable bonding material 254, optically attaches to the back surface 244 of the substrate. The visual display device (not shown in the drawings) can be, for example, a 10.4"liquid crystal display. Alternatively, the visual display device can include a reverse projection screen that is optically attached to the screen. In this way, a design engineer can locate a visual touch / display interface on an uninterrupted surface of, for example, a restaurant back counter to order food, or a desk of an office worker as an Internet interface. In the lower surface 244 of the substrate 246, four multi-element louvers 234, and four Rayleigh wave wedge transducers 230, are provided in one configuration similar to, for example, the system shown in Figure 1. Note that the usual acoustic paths between the pairs of directional reflection antenna 232 are blocked by the acoustic optical bonding junction 254 of the visual display device. Between the directional reflector antennas 232 and the visual display device there are grids 234 placed. Many options are available for the manufacture of grating and directional reflection antennas, including printing, plotting, acid corrosion, and other ablative processes or additives. The grid pairs on the upper and lower surfaces serve as acoustic pathways for transferring the energy of the Rayleigh waves 248, 252 between the two surfaces. In a preferred embodiment, a volume shear wave 250 that propagates to TB = -45 ° with respect to the vertical axis is coupled to the louvers 234, 240 and consequently satisfies the condition for F = l for the glass of soda-lime You can calculate the spacing, p, of the grid, with the help of the following equation: p = (VR / f) / (l-sin (0B) + (VR / VB)) For example, for an operating frequency of f = 5 MHZ, a Rayleigh wave velocity of VR = 3.16 millimeters / μsecond, and a volume velocity (shear) of VB = 3.43 millimeters / μsecond, and TB = -45 °, the spacing of the grid is p = 383 μm. The structure of the grid can be, for example, 1 centimeter wide, and contains approximately 25 grills. This embodiment illustrates the utility of an acoustic path which is a form of grid transducer, and more generally the use of the grid transducer mechanism in one embodiment, without a piezoelectric element directly attached to the substrate.

EXAMPLE 20 In accordance with the present invention, the grid does not need to be a series of lines on a flat surface, but may include more advanced design considerations. For example, it allows the use of a single transducer for multi-axis sensitivity. In this way, a common X / Y receiving or transmission grid transducer is possible. Referring to Figure 9, one embodiment of a common X / Y grid transducer is where the piezoelectric elements 60a and 60b are replaced with a single piezoelectric element approximately doubled in length. Optionally, the two sets of grids 54a and 54b can be extended, with the purpose of overlapping, forming a grid structure superimposed with two useful two-dimensional Fourier components. Alternatively that grid pattern of overlapped lines can be replaced with the negative of the grid pattern, ie a lattice of reflecting points with a unitary cell in the shape of a diamond. Figure 25 shows a grid transducer of similar design with a horizontally mounted piezoelectric element 220, that is, TB = 0 °. In this case the grid is an array of square or rectangular points 222, whose center-to-center spacing in the directions both X and Y is approximately one wavelength of, for example, Rayleigh waves. The piezoelectric element 220 under this grid 222 will respond to the signals from the directional antennas at both X 224 and Y 226. It is noted that the signal generated by the piezoelectric element 222 may include a plurality of frequency components. The spacing of the elements along any axis will determine the dispersion characteristics, in such a way that the grid can be selective for frequencies along axes that differ, in this way, in the case where TB = 0 °, a rectangular lattice would allow a first frequency to propagate along an axis, and a second frequency to propagate along a second axis. For the case where TB is different from 0 °, the rectangular lattice is replaced with a parallelogram lattice.

EXAMPLE 21 Figures 26A and 26B provide an example of a non-flat detector, for example, hemispherical, where the tactile surface corresponds to everything north of the "Tropic of Cancer" at latitude 23.5 ° North, and the region between the equator and the Tropic of Cancer is available for directional antennas and transducers . Figure 26A provides a Mercator projection depicting the touch zone, two transmission grid transducers, two directional transmitting reflection antennas, two directional receive reflection antennas, and two receive grid transducers. These elements form two detector subsystems, which are also shown in the projection of the plan view of Figure 26B. Together, these two detector subsystems (typically designed to overlap slightly by extending and superimposing the directional reflection antennas) allow the measurement of a coordinate over the entire tactile zone. That detector can serve as an "ultrasonic tracking ball", that is, an input device without any moving part with the appearance, feel and function of a mechanical tracking ball. One "rolls" this ultrasonic tracking ball by moving one's finger in the touch zone with a movement of the component in the X direction. The associated electronics of the controller can process the touch information and send data to the main computer in the same format, as a standard mechanical tracking ball.

Additional detector subsystems may be superimposed on the detector subsystems shown in Figures 26A and 26B. With a total of eight grid transducers and eight directional reflection antennas, two dimensional tactile positions on the surface of the touch zone can be completely reconstructed. With a total of twelve grid transducers and directional antennas, for example, by including copies of the components shown in Figure 26A rotated by + 60 ° and -60 ° with respect to the Y axis (through pole 264) north), the touch zone can be completely covered with a redundant set of three coordinate measurements. This redundancy improves the options for the development of robust algorithms that can process multiple tactile information. The use of grid transducers enables the piezoelectric elements, the electrical connections, and perhaps the controller electronics themselves, to be placed inside the hull of the hemisphere substrate. In this way, the grid transducers enable the ultrasonic tracking balls with mechanical constructions of robustness and reduced size. In one embodiment, the substrate is formed of a hemispherical steel cassette of 15 centimeters in diameter and 3 millimeters in thickness. That ultrasonic tracking ball can be subjected to considerable physical abuse and still remain fully functional Accordingly, an input device having tracking ball functionality is provided for public access kiosks. In an alternative embodiment, the hemispherical of the substrate is deformed to provide a better ergonomic fit to the user's hand. Note that this is not an option for a mechanical tracking ball. In still another embodiment, the substrate is formed of a hemispherical hull 5 centimeters in diameter and 3 millimeters thick polystyrene, for example, Styron® 666 from Dow Chemical. Note that in this embodiment, the substrate, including the directional reflection antennas, the gratings, and the angled surfaces for mounting the piezoelectric elements of the grid transducers, may be included in a mold design. It supports low cost manufacturing processes. Optionally, the operating frequency for that polystyrene detector is 2 MHz. Given a Rayleigh wave velocity of 0.99 millimeters / μsec, as can be calculated by the shear stress wave in volume and the pressure velocities, the length of wave? R is approximately 1/2 millimeter. Note that this is essentially the same as the Rayleigh wavelength in glass at an operating frequency of about 5 MHz. Since the acoustic attenuation is a monotonously strongly increasing function, that lowered operating frequency ensures that the attenuation acus- It is low enough to support the maximum path length of less than 15 centimeters for a detector 5 centimeters in diameter. In published literature, Styron® 666 stands out among polymers as having low acoustic attenuation for pressure waves in volume: 1.8 dB / cm at 5 MHz. See, (see, for example, http: // www. ultrasonic.com/Tables/plastics.html). At 2 MHz scale, this is less than about 0.72 dB / cm, or about 10 dB for a path length of 15 centimeters. U.S. Patent No. 5,648,643 describes the use of polystyrene in shear mode acoustic touch screens. Since Rayleigh waves are a mixture of shear and longitudinal acoustic energy, it is believed that acoustic losses of similar scale will be observed, and that acoustic touch screen controller designs existing in that detector system can be employed. In the detector subsystems Rl / Tl and R2 / T2 shown in Figures 26A and 26B, the directional transmitting antenna 270 follows a section of a large circle intersecting the X axis, and is rotated by an angle? towards the X axis with respect to the equatorial plane 260. The angle of inclination, say? = 20 °, is less than the latitude 23.5 ° of the Tropic of Cancer 262. You can use the grid transducer shown in Figure 15. Either the piezoelectric elements 266, 268 are mounted with its long axis in the vertical direction and the grid is designed for an emission angle of EE =?, or can a design be used in that? = 0 ° in which the entire structure of the grid transducer itself, including the piezoelectric element 266, 268, is rotated by the angle α. One option is a design in which F = 1, in which the shear mode piezoelectric elements 266, 268 are mounted on the polystyrene substrate, with a negative inclination angle of TB = 30 °. The design of the directional reflection antenna 270, 272 is very independent of the type of transducers that are used, but is described later for integrity. The directional reflection antennas 270, 272 form segments of large circles. Directional transmission antenna 270 follows the following trajectory on the surface of the hemisphere: x (s) = R • cos (trs / 2) and (s) = R • sin (?) • sin (7rs / 2) z (s) ) = R • cos (?) • sin (trs / 2) Here, R is the radius of the hemisphere, for example, 2.5 centimeters. The definitions that are used in the present for the directions x, y, and z are shown in Figure 26B. Similarly, the path for the receiving directional antenna is as follows. and (s) = R • sin (?) • sin (7rs / 2) z (s) = R • cos (?) • sin (ps / 2) In these formulas, s is the parameter of the path that nominally increases monotonically with the delay time corresponding to the corresponding acoustic trajectories 274, between the transducers transmission 266 and reception 268. In this example, the directional antenna will start with a small positive value of s, and end at a value of s slightly greater than one, in order to provide the overlap between the pairs of detector subsystems described previously. Now consider the coordinate system (?, F) for the surface of the hemisphere defined by the following relationships. -tr / 2 < ? < tr / 2 0 < f < px (?, f) = R • cos (0) • cos (ó) y (?, f) = R • cos (0) • sin () z (?, f) = R • sin (?) In terms of this coordinate system, the directional transmission antenna follows the path:? (s) = arcs (cos (?) • sin (ps / 2)) f (s) = arctan (sin (?) • tan (trs / 2)) and the receiving directional antenna follows the following path:? (s) = arcs (cos (?) • sin (7rs / 2)) f (s) = arctan (sin (?) • tan (7rs / 2)) The acoustic path through the tactile zone is also a segment of a large circle. The large circle connecting the directional transmitting antennas 270 and receiving antenna 272 for the path parameter s is a segment of a line of length with respect to the Z axis, namely the next section of a large circle: -arcs (eos) (?) «Sin (trs / 2)) < 0 < arcsen (eos (?) «sin (ps / 2) f = arctan (sin (?) • tan (ps / 2)) Although Love waves and other acoustic modes may be useful for some modalities, it is described below greater detail a design in which Rayleigh's VR velocity waves are used The delay time as a function of the path parameter is given as follows: T (s) = (R * (s / 2)) / VR + 2R »arcsen (cos (?) * Sin (s / 2)) / VR + (R * (trs / 2)) A ^ R The delay time can also be expressed in terms of the one-touch f coordinate that intercepts the acoustic trajectory T () = (2R / VR) • arctan (tan (f) / sin (?)) + 2R • arcs (cos (?) • sin (arctan (tan (f) / sin (?))) / VR With this analytical expression, a search table can be calculated.This search table can be used in the real-time microprocessor code to convert measured delay times of conversion of the signal disturbances -in the tactile coordinate f The spacing and angles of the reflec can be calculated using the principles described previously.

Let's refer again to the first detector subsystem in Figure 26B. For the directional transmitting antenna, the reflector spacing vector is S = 27rn (kt (s) - kp (s)) | kt (s) - kp (s) | 2, where kt (s) and k_ (s) can be calculated by the trajectory of the known directional antenna (? (s), f (s)) given previously by the following Expressions kt (s) = (2tr /? R) • (-sen (trs / 2), sin (?) • cos (? rs / 2), cos (?) • cos (? rs / 2)) p (s) ) = (2n7? R) • (-cos (f (s)) sin (0 (s)), -sen (f (s)) sin (0 (s)), cos (0 (s)) Here? R represents the Rayleigh wavelength, the magnitude of S provides the center-to-center distance between the reflectors in the direction perpendicular to the reflectors, and the direction of S is perpendicular to the reflector elements. they have shown and described novel receptacles and novel aspects of touch screen transducer systems, which fulfill all the objectives and advantages that were sought for them, however, for those skilled in the art many changes, modifications, variations, combinations, will be evident. subcombinations and other uses and applications of the present invention, after considering this specification and the accompanying drawings describing the preferred embodiments thereof, all those changes, modifications, variations and other Uses and applications that do not depart from the spirit and scope of the invention are considered covered by the invention, which will be limited only by the claims that follow.

Claims (70)

1. An acoustic touch sensing device, comprising: (a) a substrate, having a surface; (b) an acoustic wave transducer, coupled to a first wave, which is a wave in volume, which propagates through the substrate along an axis intersecting that surface; (c) a diffraction acoustic wave mode coupler, which couples the energy of the first wave to a second wave having a waveform converted with appreciable energy on the surface, and propagating along a parallel axis to the surface; and (d) elements for detecting a disturbance of the energy of the second wave.

The device, according to claim 1, wherein the acoustic wave transducer comprises elements for propagating waves in volume in an oblique direction with respect to said surface.

The device, according to claim 1, wherein the acoustic wave transducer couples the first wave directly to the diffraction acoustic wave mode coupler.

4. The device, in accordance with the claim 1, wherein the acoustic wave transducer couples the first wave to the diffraction acoustic wave mode coupler, through at least one acoustic reflection in the path of the first wave.

The device, according to claim 1, wherein the diffraction acoustic wave mode coupler is coupled to a third wave comprising energy of the first wave having a wave mode different from the first wave.

The device, according to claim 1, characterized in that it also comprises a second acoustic wave transducer, which is coupled to an eighth wave, which is a wave in volume, which propagates through said substrate along the wavelength. an axis that intersects the surface, the diffraction acoustic wave mode coupler couples the energy of the eighth wave to a ninth wave, different from the second wave, which has a wave mode converted with appreciable energy on the surface, and propagates along an axis parallel to the surface.

The device, according to claim 1, wherein the diffraction acoustic wave mode coupler comprises a set of scattering centers.

8. The device, according to claim 7, wherein the set of dispersion centers It is placed on said surface.

The device, according to claim 1, wherein the diffraction acoustic wave mode coupler comprises a set of spaced elements having an acoustic characteristic that differs from the surrounding areas of the substrate.

The device, according to claim 9, wherein the elements comprise elongated linear grids, spaced in a regular manner.

The device, according to claim 9, wherein the elements comprise elongated curved grids, spaced in a regular manner.

The device, according to claim 1, wherein the diffraction acoustic wave mode coupler comprises a periodic acoustic disturbance of the substrate.

The device, according to claim 1, characterized in that it also comprises a set of elements placed along at least a portion of a path of the second wave, to reflect a portion of the energy of said second wave. , as a set of fourth waves, each propagating in parallel to the surface, along an axis other than a propagation axis of the second wave.

14. The device, in accordance with the claim 13, wherein the set of fourth waves has different characteristic time delays that vary incrementally and monotonously.

15. The device according to claim 14, characterized in that it also comprises a set of elements placed along a path that intersects the axes of the set of fourth waves, which reflect at least a portion of the energy of the set of fourth waves towards a common receiver, the common receiver producing a signal related to an energy of the reflected portion of the set of fourth waves.

The device, according to claim 15, wherein the elements for detecting an energy disturbance of the second wave, comprises elements for analyzing a signal from the common receiver, to detect a disturbance of energy received by them.

The device, according to claim 1, characterized in that it also comprises a plurality of said acoustic wave transducers, each coupled to a different volume wave propagating through the substrate, along an intersecting axis the surface, the energy of the waves in different volumes being coupled to a wave that has a wave mode converted with appreciable energy on the surface, and that propagates along an axis parallel to the surface, through a diffraction acoustic wave mode coupler.

18. The device according to claim 17, wherein at least two of the converted wave modes coupled to the different volume waves propagate along parallel paths.

The device, according to claim 1, characterized in that it also comprises a wave disperser and a wave capacitor, each sequentially placed along a different portion of an acoustic energy path of the wave that has appreciable energy in said surface, the wave disperser and the wave capacitor being separated by a portion of the surface adapted for tactile detection.

The device, according to claim 19, characterized in that it also comprises a second acoustic wave transducer, coupled to a fifth wave, which is a wave in volume, which propagates through the substrate along an axis that intersects the surface, the fifth wave being coupled to a sixth wave that has a wave mode converted with appreciable energy on the surface, and that propagates along an axis parallel to the surface; the second wave having a path that includes at least a portion of the wave disperser, and the sixth wave having a path that includes at least a portion of the capacitor.

21. The device, according to claim 1, wherein the detection element detects a location of the disturbance.

22. The device, according to claim 1, wherein the surface is flat.

The device, according to claim 1, wherein the surface is smooth and not flat, the axis of propagation of the second wave changing locally to conform to the surface.

The device, according to claim 1, wherein said acoustic wave transducer comprises a flat acoustic coupling surface, the flat acoustic coupling surface being inclined with respect to a portion of the surface intersected by the first wave.

25. The device, according to claim 1, wherein the acoustic wave transducer comprises a piezoelectric element.

26. The device according to claim 1, wherein the acoustic wave transducer comprises a diffraction acoustic wave coupler, which couples a seventh acoustic wave with the first wave.

27. The device, according to claim 1, wherein the first wave has a propagation axis whose projection on the surface differs from a propagation axis of the second wave.

The device, according to claim 1, wherein the first wave has one or more oscillation components that are selected from the group consisting of a pressure mode, a vertical shear mode, and a horizontal shear stress.

29. The device, according to claim 1, wherein said second wave has one or more oscillation components that are selected from the group consisting longitudinally, horizontally polarized shear stress mode, and shear stress mode. vertically polarized.

30. The device, according to claim 1, wherein the second wave comprises a wave of the Rayleigh type.

31. The device, according to claim 1, wherein said second wave comprises a wave of the Love type.

32. The device, according to claim 1, wherein the substrate has non-homogeneous acoustic properties.

The device, according to claim 1, wherein the substrate comprises layers parallel to said surface, having different acoustic properties.

34. The device, according to claim 1, wherein the first wave propagates along an axis having an inclination of at least about | p / 8 | radians, with respect to a plane tangent to said surface at that intersection.

35. The device according to claim 1, wherein the first wave comprises a shear mode component, and has a projection of a propagation axis having an angle whose magnitude is at least about 45 ° with respect to to an axis of propagation of the second wave.

36. The device according to claim 1, wherein said acoustic wave transducer is coupled to a volume wave of pressure mode, and the second wave comprises a horizontally polarized shear stress wave.

37. The device according to claim 1, wherein substantially only the first wave, propagating parallel to the axis intersecting the surface, satisfies the horizontal components of the Bragg scatter conditions of the acoustic wave mode coupler. of diffraction, in a particular acoustic frequency.

38. The device, according to claim 1, wherein the wave-acoustic diffraction mode coupler comprises a set of elements formed on the surface, from a composition comprising glass frit.

39. The device according to claim 1, wherein the diffraction acoustic wave mode coupler comprises a set of elements formed on the surface, from a composition comprising a polymer matrix.

40. The device according to claim 1, wherein the diffraction acoustic wave mode coupler comprises a set of elements formed on said surface, from a polymer filled with a dense inorganic composition.

41. The device according to claim 1, wherein the diffraction acoustic wave mode coupler comprises a set of slots formed on said surface.

42. The device according to claim 1, wherein the diffraction acoustic wave mode coupler serves as an acoustic lens.

43. The device according to claim 1, wherein the diffraction acoustic wave mode coupler satisfies a Bragg scattering condition for coupling at least two waves in volume to at least two useful waves having a wave mode converted, each with appreciable energy on the surface, and each propagating along an axis parallel to the surface.

44. The device according to claim 1, wherein said acoustic wave transducer is coupled to the first wave in the substrate, having a propagating axis substantially normal to the surface.

45. The device, according to claim 1, wherein the first wave resonates in the substrate.

46. The device according to claim 1, wherein a portion of an acoustic wave path includes partial acoustic reflections having reflected angles that are totaled to an integral multiple of 2p radians.

47. The device according to claim 1, wherein the acoustic wave transducer is coupled to a signal, and the substrate exhibits an acoustic resonance at a frequency, the acoustic wave transducer being coupled to the acoustic resonance at said frequency. , to thereby achieve substantially a maximum relative acoustic energy coupling efficiency between the first wave and the signal, for a given signal amplitude.

48. The device according to claim 1, wherein the substrate is a material that is selected from the group consisting of soda-lime glass, borosilicate glass, a crown glass, a glass containing barium, a glass that contains strontium, a glass that contains boron, a laminated glass capable of withstanding the propagation of Love waves; a ceramic, aluminum, a coated aluminum substrate capable of withstanding Love's wave propagation, and a polymer of low acoustic loss.

49. The device according to claim 1, characterized in that it also comprises elements to reflect portions of the second wave as a set of waves that varies in increments, comprising an array of elements formed during an integral operation with an operation that forms the diffraction acoustic wave mode coupler.

50. The device according to claim 1, characterized in that it also comprises elements for selectively reflecting portions of said second wave as a set of scattered waves propagating through the substrate, the selective reflection elements having a set of Fourier components that are poorly coupled to the unconverted portions of the first wave in volume.

51. The device according to claim 1, wherein the diffraction acoustic wave mode coupler comprises at least one element having an asymmetric profile along a propagation axis of the second wave.

52. The device, according to claim 1, wherein the acoustic wave transducer comprises a ceramic piezoelectric element.

53. The device, according to claim 1, wherein the acoustic wave transducer comprises a piezoelectric polymer element.

54. The device according to claim 1, wherein the acoustic wave transducer is mounted to said substrate in a mechanically protected region on at least two sides by the substrate.

55. A substrate for an acoustic detection device, having a region, and a surface, comprising: (a) an acoustic transducer, which couples to a wave in volume on the substrate, having a propagating axis that intersects the surface; (b) a diffraction acoustic wave mode coupling structure, formed near the surface, adapted to convert the energy of the wave sound in volume to a wave propagating along an axis parallel to the wave the surface; and (c) elements for detecting the converted acoustic wave energy in an adapted manner to determine a position of a disturbance thereof.

56. The substrate, in accordance with the Claim 55, wherein the sensing element comprises elements for coupling the converted acoustic wave energy with an incrementally variable set of scattered waves propagating through said region.

57. The substrate, according to claim 55, characterized in that it further comprises a plurality of acoustic transducers coupled respectively to a wave in volume in the substrate, each wave in volume having a propagation axis that intersects the surface at a varying phase shift. in increment.

58. A method for detecting touch on a substrate having a surface, comprising the steps of: transducing a wave in volume into the substrate, which propagates through the substrate along an axis intersecting the surface; coupling in a diffraction manner the energy of the wave in volume to a wave that has a wave mode converted with appreciable energy on the surface, and that propagates along an axis parallel to the surface; and detect a disturbance of the wave that has a converted wave mode.

59. The method according to claim 58, wherein a mode of the wave in volume is converted between the transduction and the coupling in the manner of diffraction.

60. The method, in accordance with the claim 58, characterized in that it also comprises the step of reflecting the wave in volume between the transduction and the coupling in the manner of diffraction.

61. The method, according to claim 58, characterized in that it also comprises the step of focusing the wave having a converted wave mode.

62. The method according to claim 58, characterized in that it also comprises the step of reflecting a portion of the energy of the wave having a converted wave mode, as a set of temporarily dispersed waves, each propagating parallel to the surface along a redirected axis.

63. The method, in accordance with the claim 62, characterized in that it also comprises the step of reflecting at least a portion of the energy of the variably temporally dispersed waves, towards a common receiver.

64. The method, in accordance with the claim 63, characterized in that it also comprises the step of analyzing a disturbance of the energy received by the common receiver.

65. The method, in accordance with the claim 58, characterized in that it also comprises the step of resonating the wave in volume in the substrate.

66 The method, according to claim 58, characterized in that it also comprises the steps of scattering the wave having a wave mode converted through from a region adapted to detect touch, and to condense the scattered wave after traversing the region adapted to detect touch.

67. The method according to claim 66, characterized in that it also comprises the step of coupling in a diffraction manner at least a portion of the dispersed wave condensed to a wave in volume, and transducing the condensed dispersed wave coupled.

68. The method, according to claim 58, characterized in that it also comprises the step of analyzing a position of the disturbance detected.

69. The method, in accordance with the claim. 58, wherein the energy of the wave in volume is dispersed as a plurality of wave modes, at least one scattering center, including the wave having a converted wave mode, characterized in that it also comprises the step of distinguishing so selective the wave that has a converted wave mode.

70. The method according to claim 69, wherein the wave having a converted wave mode is selectively distinguished by an interaction of the acoustic energy of the wave in volume with the at least one center of dispersion and an additional scattering center oriented with respect to the dispersion center, to selectively generate acoustic wave interference.