WO2001002943A1

WO2001002943A1 - Acoustic touch sensor

Info

Publication number: WO2001002943A1
Application number: PCT/JP2000/004294
Authority: WO
Inventors: Shigeki Kanbara; Hiroshi Kaneda
Original assignee: Touch Panel Systems Corporation
Priority date: 1999-06-30
Filing date: 2000-06-29
Publication date: 2001-01-11
Also published as: JP2001014092A; AU5705800A; TW538367B

Abstract

An acoustic transducer for practically efficient acoustic mode conversion is used to generate a high-intensity signal in a touch-sensitive coordinate input device. A device according to the invention comprises acoustic transducers (piezoelectric oscillators) (3a, 4a) for generating a bulk wave (first wave) toward the surface (2) of a substrate (1), acoustic gratings (diffraction gratings) (5a-6b) for conversion between bulk wave and surface acoustic wave (second wave), and means for detecting the disturbance of the second wave on the surface of the substrate. The acoustic gratings (5a-6b) have the following characteristics: (i) grating thickness h=15 to 39 νm, (ii) W/P=0.4 to 0.95, where W is grating size and P is grating pitch, (iii) h2L⊃750 νm2-mm, where L is the coupling length of acoustic grating, (vi) ςh2L⊃3.5x10?6 νm2¿-mm-kg/m3, where ς is grating density.

Description

Acoustic contact detection device

TECHNICAL FIELD The present invention relates to an acoustic contact detection device for detecting a contact position acoustically, such as an ultrasonic touch panel, or a touch coordinate input device, and a substrate therefor. Night view technology

The evening touch panel is widely used as an input device for an interactive convenience viewing system, such as a kiosk information terminal and an order input method for restaurants. As the main touch panel, a resistive touch panel, a capacitive touch panel, and an acoustic touch panel are known. Acoustic touch panels, especially ultrasonic touch panels, are particularly advantageous when very tough touch-sensitive surfaces and improved transmission of display images are required.

Various types of transducers (especially トランス edge transducers) are used in acoustic type touch panels, which directly couple the piezoelectric vibrator and the touch panel. A transducer is one or a series of physical elements that convert energy from one form to another, including conversion between acoustic wave modes and between electrical energy and acoustic energy. Contains element. A typical piezoelectric transducer is formed of a prismatic piezoelectric vibrator with a conductor on the surface, and the elements on the substrate surface

It is acoustically coupled to the substrate surface by a metal electrode that comes into contact with the substrate (eg, a wedge material) or by arranging the piezoelectric element surface on the substrate surface.

The edge transducer uses a phenomenon in which a sound wave is refracted when a sound wave is obliquely incident on a boundary surface between different media.

1 Excites waves and plate waves on the substrate. A typical edge transducer is composed of a piezoelectric vibrator attached to one side and a plastic wedge whose hypotenuse is bonded to a substrate (such as glass). Coupling with bulk waves through wedge material. Bulk waves are refracted at a critical angle, or “wedge angle”, and propagate in the plane direction of the glass, and surface waves are refracted at the critical angle and propagate as bulk waves. Thus, edge transducers can be used to both transmit and receive surface waves, such as Rayleigh and Love waves, and plate waves, such as Lamb waves.

In contrast, a direct coupling of a piezoelectric vibrator or an edge transducer generally directly excites a sound wave having a large amount of energy on the substrate surface. Edge transducers are most naturally used for coupling with plate waves. Some work has been done to develop edge transducers that couple to Rayleigh waves. Such edge transducers are small, but the exposed piezoelectric transducers remain vulnerable.

The part where the edge-type transducer is located on the surface of the sunset panel is necessarily higher than the surface of the nonel. Also, when the display is formed of a panel such as a general cathode ray tube, there is a space between the curved panel and the outer frame surrounding the curved panel. I do. However, when the display is formed of a flat panel such as a liquid crystal display or a plasma display, there is no gap between the panel and the outer frame around the surface of the panel covered with the outer frame. No space to place page transducer. Therefore, the use of an edge transducer makes it difficult to adapt the ultrasonic touch panel to a flat panel. In addition, the applicable display and outer frame structure are greatly restricted. In particular, in an acoustic sunset sensor using Rayleigh waves, an edge transformer The use of a transducer can complicate mechanical design and limit options.

U.S. patent application Ser. No. 08 / 610,260 states that the edge transducer is mounted on the front slope adjacent to the sunset area and the edge transducer is lower than the front height of the panel substrate. It has been proposed. However, such a design not only causes acoustic loss, but also necessitates an increase in the edge width of the panel substrate, contrary to what is required in a liquid crystal display (LCD) design.

Thus, edge transducers are not suitable for liquid crystal displays (LCDs). Japanese Patent Laid-Open Publication No. Hei 10-244443 discloses a grating transducer (diffractive acoustic wave transducer) in order to solve the above problems. According to this document, the distance (pitch) between the gratings of the diffraction grating constituting the diffractive acoustic wave transducer is about 0.01 to: L0 mm, the grating width is about 0.01 to: I0 mm, and the height of the grating is It is stated that the glass frit can be selected from a range of 5 mm or less (preferably 0.1 to l mm). In Example 4, glass frit (density of about 5.6 g / cm It is also disclosed that a grating transducer having a grating height of 4 μμπι and a grating interval of 0.89 mm was formed using ³ ). In addition, Takeuchi reports that the thickness and density of the grating and the bond length are important for obtaining a large perturbation. This grading transducer attaches a piezoelectric vibrator to the back surface of the glass substrate or to a third surface provided between the end surface and the back surface to excite bulk waves inside the glass substrate, and this bulk wave is applied to the front surface. The mode conversion by the diffraction grating provided excites a wave that concentrates energy on the surface represented by surface acoustic waves. Since this transducer does not require a ゥ edge, surface irregularities can be reduced to almost zero. Also, since the piezoelectric vibrator can be installed on the back side, the cable wiring can also be arranged on the back side of the board, leading to space saving. However, even if a grating transducer (diffractive acoustic wave transducer) composed of a diffraction grating is formed on the surface of the substrate, the mode conversion of the acoustic wave cannot be performed reliably due to the perturbation period. In particular, mode conversion cannot be performed with high efficiency even if the ratio between the lattice wire diameter and the distance between lines is set to a ratio of 1: 1 which is considered to be theoretically the highest in mode conversion. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an acoustic contact detection device (or Yutzuchi-type coordinate input device) that can convert an acoustic wave mode with high efficiency by a diffractive acoustic wave transducer, and a substrate therefor.

Another object of the present invention is to provide an acoustic contact detection device (or an evening switch) capable of obtaining a high signal strength by performing mode conversion at a practically high level by a diffractive acoustic wave transducer and detecting a contact position with high accuracy. And a substrate therefor. Disclosure of the invention

The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems. As a result, the profile (shape) of the diffraction grating formed by the printing method is not a rectangular parallelepiped, but necessarily a semi-cylindrical shape. When used, the first term of the Fourier transform, which is most important for diffraction scattering, is reduced, and even if the thickness of the grating is increased to 40 μΐϊΐ or more, the productivity is reduced and the mode They found that the conversion efficiency did not improve, and completed the present invention.

That is, the acoustic contact detection device of the present invention comprises: (a) a substrate having a surface; (b) a first wave as a bulk wave propagating through the substrate along an axis intersecting the surface. An acoustic wave transducer for: (c) having a mode of a converted wave having more energy at the surface and propagating along an axis parallel to the surface A second acoustic wave transducer for coupling the second wave with the first wave, and (d) means for detecting a perturbation in energy of the second wave. In such an apparatus, the diffractive acoustic wave transducer has at least one of the following characteristics (i) to (iv).

(i) The thickness h of the grating constituting the diffractive acoustic wave transducer is 15-39μπι

(ii) The ratio W / P between the diameter W of the grating constituting the diffractive acoustic wave transducer and the pitch P is 0.4 to 0.95.

(iii) Assuming that the coupling length of the diffractive acoustic wave transducer is L and the thickness of the grating constituting the diffractive acoustic wave transducer is h, ² : 1 is at least 750 111 ² 'mm

(iv) Assuming that the coupling length of the diffractive acoustic wave transducer is L, the thickness of the grating constituting the diffractive acoustic wave transducer is h, and the density of the material constituting the grating is p, ph ² L is 3.5 It is ^{^{X 10 6 μπι 2 · mm ·}} kg / m 3 or more

The present invention further includes a substrate for an acoustic detection device, the substrate comprising: (a) an acoustic wave transducer coupled to a bulk wave having a propagation axis crossing the substrate surface in the substrate. (B) a diffractive acoustic wave transducer formed in the vicinity of the surface for converting acoustic wave energy of a bulk wave into a wave propagating along an axis parallel to the surface; And (c) means for detecting the acoustic energy converted with respect to the location of the perturbation.

In the present invention, since the diffractive acoustic wave transducer has specific characteristics, the mode conversion between the bulk wave and the acoustic wave (surface wave or plate wave) can be performed with high efficiency. Therefore, even if a diffractive acoustic wave transducer is used, the contact position can be detected with high signal strength. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic perspective view showing an example of the device of the present invention.

FIG. 2 is a schematic sectional view of the apparatus shown in FIG.

FIG. 3 is a graph showing the results in Example 1.

FIG. 4 is a graph showing the results of Example 2.

FIG. 5 is a graph showing the results of Example 3.

FIG. 6 is a graph showing the results of Example 4. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings as necessary. FIG. 1 is a schematic perspective view showing an example of the apparatus of the present invention, and FIG. 2 is a schematic sectional view of the apparatus shown in FIG.

The device capable of acoustically detecting a contact position (the Utsuchi-type coordinate input device) includes a substrate 1 as a propagation medium having a surface through which an acoustic wave (surface wave or plate wave) can propagate, and a bottom surface of the substrate ( Or acoustic transducers 3 and 4 which are mounted on the rear surface) and are composed of piezoelectric vibrators. The surface of the substrate 1 has a display area (image display area) 2 which is symmetrical with respect to the X-axis and Y-axis directions. In addition, the acoustic wave transducers 3 and 4 are not formed with a edge-type transducer but are formed of plate-shaped piezoelectric vibrators in order to reduce the thickness and weight of the device.

Acoustic wave transducers 3 and 4 consist of transmitting transducers 3a and 3b, which are attached to the X-axis and Y-axis starting regions (part of the bottom corners of the X-axis and Y-axis in this example) on the back of substrate 1; It consists of a pair of receiving transducers 4a and 4b attached to the X-axis and Y-axis end areas (part of the bottom corners of the X-axis and Y-axis in this example) on the back of the board. The transmitting transducers 3a and 3b are Function as bulk wave generating means for propagating a bulk wave (which may be a longitudinal mode or a transverse mode) in a direction crossing the surface (front surface) of the substrate, and the receiving transducers 4 a and 4 b It functions as bulk wave receiving means for receiving a bulk wave propagating in the substrate in a direction intersecting from the surface (front surface) of the substrate 1. That is, the acoustic wave transducers 3 and 4 transmit a bulk wave (first wave) propagating through the substrate 1 along an axis crossing the surface of the substrate 1, in other words, a propagation crossing the surface. It is coupled to a bulk wave having an axis.

From the oscillation transducers 3 a and 3 b of the acoustic wave transducers 3 and 4, a bulk wave (first wave) is emitted through the substrate 1 toward a mode conversion portion (perturbation region or oscillation region) on the surface (front surface). The bulk wave arriving at the mode conversion part is converted into an acoustic wave (differential acoustic mode coupler) 5a, 5b provided at the mode conversion part. Surface waves or plate waves), especially surface acoustic waves (second waves). This surface acoustic wave has a mode of a converted wave having a large amount of energy on the substrate surface. That is, the diffractive acoustic wave transducers (acoustic mode couplers) 5 a and 5 b function as acoustic wave generating means, and are arranged along the bulk wave (first wave) and an axis parallel to the surface of the substrate 1. The surface wave (second wave) propagating near the substrate surface is coupled, and the mode of the acoustic wave can be converted into a bulk wave and a surface wave. In this example, the diffractive acoustic wave transducers 5a and 5b are formed as diffraction gratings (gratings) formed of linear gratings by a screen printing method. It is formed in a curved or round shape.

The acoustic wave transducer has at least one of the following characteristics (i) to (iv) in order to increase the signal strength (output voltage) by improving the mode conversion efficiency of the acoustic wave transducer. I have.

(i) The thickness (height) h of the grating constituting the diffractive acoustic wave transducer is 15 To 39 μπι (preferably 20 to 38 μπι, more preferably 25 to 37 μπι, particularly about 30 to 37 μπι), and usually about 27 to 36 μπι (eg, 30 to 35 μπι). If the grating thickness h is small, the mode conversion efficiency decreases, and if it is too large, the mode conversion efficiency does not improve much, possibly because of the cross-sectional shape of the lattice.

(ii) The ratio W / P of the diameter W of the grating constituting the diffractive acoustic wave transducer to the pitch P is 0.4 to 0.95 (preferably 0.6 to 0.95, more preferably 0.7 to 0.95). 0.95, especially about 0.75 to 0.95). If the value W / P is too small, the mode conversion efficiency decreases, and if it is too large, the grating cannot be formed accurately.

(iii) When the coupling length of the diffractive acoustic wave transducer is L and the thickness of the grating forming the diffractive acoustic mode coupler is h, the value h ² L (unit μπι ² -mm) is 750 or more (for example, 760-5000, preferably 1500-4000, more preferably 2000-4000, especially about 2200-4000) and usually about 2500-4000. If the value h ² L is too small, the mode conversion efficiency decreases, and if it is too large, the mode conversion efficiency does not improve much.

(iv) When the coupling length of the diffractive acoustic wave transducer is L, the thickness of the grating constituting the diffractive acoustic mode coupler is] !, and the density of the material constituting the grating is p, ph ² L (unit ^{μπι 2 · mm · kg / m} 3) is, 3. 5x l 0 ⁶ or more (e.g., 5x l 0 ⁶ ~2.

5 x 10 \ preferably 1 X 10 ^⁷ ~2x 10 ^7, more preferably from 1. 2x 10 7~2x 10 about ^7). Beat the value ph ² L is too small mode conversion efficiency low, it does not improve much mode conversion efficiency be too large.

The diffractive acoustic wave transducer only needs to have at least one of the above characteristics (i) to (iv), and may have a plurality of characteristics. For example, a combination of two characteristics [combination of (i) and (ii), combination of (i) and (iii), combination of (i) and (iv), and (ii) and ( i ii), the combination of (ii) and (iv), etc.], 3 Combinations of the three properties [for example, the combination of (i), (ii), and (iii), the combination of (i), (ii), and (iv), (ii), (iii), and (iv) And a combination of the four characteristics.

X-axis reflection means 7 a and 7 b extending in the X-axis direction are provided on opposite sides of the first side of the surface of the substrate 1, respectively. Y-axis reflecting means 8 a and 8 b extending in the Y-axis direction are provided to face each other. Each reflection means consists of a reflection array consisting of an array group inclined at an angle of about 45 ° to the traveling direction of the surface acoustic wave, and a part of the surface acoustic wave passes through the array of the reflection array. It is possible. Therefore, the surface acoustic waves (surface waves or plate waves, particularly, surface acoustic waves) converted by the diffractive acoustic wave transducers 5 a and 5 b are applied to the first X-axis reflecting means (reflection array) on the surface of the substrate 1. 7) and the first Y-axis reflecting means

(Reflection array) The light is reflected in the Y-axis and X-axis directions by the reflection array 8a, and propagates throughout the display area 2 on the surface of the substrate 1.

The surface acoustic waves reflected in the Y-axis and X-axis directions are respectively

(Reflection array) 7b and the second Y-axis reflection means (reflection array) 8b are reflected in the X-axis and Y-axis directions, and the X-axis and Y-axis diffraction of the mode conversion part (reception area or perturbation area) It is directed to the acoustic wave transducers 6a, 6b. The diffractive acoustic wave transducers 6a and 6b are configured similarly to the diffractive acoustic wave transducers 5a and 5b, and convert a surface acoustic wave into a bulk wave. The converted bulk waves are received by acoustic wave transducers (X-axis and Y-axis receiving transducers) 4a and 4b each composed of a piezoelectric vibrator as described above, and are converted into electric signals. Given to

Then, utilizing the fact that the disturbed or scattered component of the received signal caused by the sunset in the image display area 2 corresponds to the attenuation information of the time-series received information, The perturbation of energy of the surface acoustic wave (second wave) on the substrate surface (and the perturbation position corresponding to the Yutzuchi position) is based on the signals from the receiving transducers 4a and 4b, which are detected by the detection means of the controller. It can be done by processing and analyzing or analyzing.

In such an acoustic contact detection device (or unit) and a substrate provided with the surface and the elements, since the diffractive acoustic wave transducer is formed by a specific diffraction grating, the efficiency of the bulk wave and the surface acoustic wave can be increased. Mode conversion can be done well. As a result, the detection intensity can be increased, and the Yuttsu position can be detected with high accuracy. Further, since the plate-like acoustic wave transducer is arranged on the back surface of the substrate and the diffraction grating is arranged on the surface of the substrate, the thickness and weight of the device can be greatly reduced. Therefore, it can be suitably applied to a liquid crystal display (LCD), a plasma display and the like.

For details of the substrate material and structure and shape of the propagation medium, acoustic wave transducers, diffractive acoustic wave transducers (acoustic wave mode couplers), reflecting means, and means for detecting perturbations, see Japanese Patent Laid-Open No. — Reference can be made to Japanese Patent Publication No. 2404443. For example, acoustic waves include ultrasonic surface acoustic waves such as Rayleigh waves, Lamb waves, Love waves, zero-order transverse waves (ZOHPS) whose vibration direction is horizontally deflected, and vibration waves that are deflected horizontally. High-order transverse waves (HOHPS).

The propagation medium can be formed of glass, ceramics, aluminum, polymer, or the like, may be a heterogeneous laminate, and the shape of the propagation medium is not particularly limited. The propagation medium may be a flat panel substrate such as a liquid crystal display or a plasma display, or may be a curved panel.

The acoustic wave transducer can be composed of a sound emitting element such as a piezoelectric vibrator / piezoelectric transducer, and a piezoelectric resonator composed of a piezoelectric substrate and various electrode structures can be used. In particular, in order to suppress an increase in thickness, it is advantageous to use a plate-shaped piezoelectric vibrator. As disclosed in U.S. Pat.No. 4,700,176 In addition, the number of acoustic wave transducers may be reduced by employing a structure in which surface acoustic waves are reflected on the opposite side of the reflection array and using a folded acoustic wave path.

Further, the acoustic wave transducer can be mounted in a proper position on the propagation medium, for example, as shown in the figure, the bottom or bottom wall of the substrate, the side or side wall of the substrate, the inclined surface formed on the lower side or side wall of the substrate, etc. Can be formed. Even in such a case, the diffractive acoustic wave transducer can efficiently and efficiently convert the acoustic wave into a bulk wave and a surface acoustic wave.

Diffractive acoustic wave transducers can be composed of grating transducers, a series of scattering centers and scattering elements, linear elements or gratings formed at intervals, and grooved scattering elements. The shape may be a dot shape, a linear shape, or the like, or an arc shape capable of converging or focusing a surface acoustic wave. Mode conversion means for mutually converting a bulk wave and a surface acoustic wave into each other and diffracting the wave in a predetermined direction is usually composed of a plurality of linearly extending linearly extending in a direction orthogonal to the traveling direction of the bulk wave. It consists of a grid (grid grid).

In a diffractive acoustic wave transducer, the width W of the grating may be selected, for example, from a range of about 0.2-0.52 mm, usually between 0.4-0.52 mm, preferably about 0.5-0.52 mm. It may be about 42 to 0.5 mm, more preferably about 0.43 to 0.49 mm. The bond length L can be selected according to the density and the number of lattices, and may be, for example, about 2 to 5 mm, preferably about 2.5 to 4.5 mm, and more preferably about 3 to 4 mm. Furthermore, the density p of the grating is advantageously larger in order of the mode conversion, for example, 4 to be selected from Og / cm ³ range of about, typically, 5~8g / cm ³ order. Further, the lattice can be formed of various materials, and usually can be formed of glass, ceramic, or the like.

The reflection array constituting the reflection means may be formed as an aggregate (reflection grating) of reflection array elements formed as projections or projections using glass or the like. It may be an assembly of reflective array elements formed as grooves. The reflection array elements are usually formed parallel to each other. To provide even acoustic energy to the receiving transducer, the spacing between the reflective array elements may be reduced as one moves away from the oscillating transducer, and the reflectivity increases as one moves away from the oscillating transducer. Is also good. Since the contact detection device (Yuuchi coordinate input device) is provided at the front of the display device, the reflection array is usually provided in the detection area (or display area) in order to avoid seeing the reflection array. It is placed around the substrate outside the box, and is covered and protected by the outer frame.

The diffractive acoustic wave transducer / reflection array is formed by printing a predetermined material (especially a paste-like material) in a predetermined pattern using a printing technique (such as screen printing), drying, and firing. be able to.

Since the device (or unit) and substrate of the present invention are thin and lightweight, they can be suitably used as a flat panel or a low curvature panel of a thin display device such as a liquid crystal display device and a plasma display device. According to the present invention, the mode of the acoustic wave can be mutually converted to the surface acoustic wave and the bulk wave with high efficiency because the diffraction acoustic wave transducer having the specific characteristics is provided. In particular, the mode can be converted to a practically high level by the diffractive acoustic wave transducer to obtain a high signal strength, and the contact position can be detected with high accuracy. Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1

By screen printing, a diffractive acoustic wave transducer (grating length) was applied to the mode conversion site on the surface of the soda lime glass substrate using glass paste as ink. 7 mm, grid width 0.45 mm, number of grids 6) were printed, and a reflective array was printed using a glass frit paste on the reflective area on the surface of the glass substrate and dried. The angle of the reflection array element is 45 ° with respect to the X axis and the Y axis. The printed pattern was fired together with the glass substrate at a firing temperature of 485 ° C. to 490 ° C. for a top keeping time of 10 minutes to obtain a glass substrate. Further, a glass substrate was produced in the same manner as above, except that the height of the grating of the diffractive acoustic wave transducer was changed.

A plate-shaped piezoelectric vibrator was bonded to the obtained glass substrate on the opposite side of the diffractive acoustic wave transducer using an ultraviolet curable adhesive, thereby producing a sample having the structure shown in FIG.

Then, the piezoelectric vibrator is electrically connected to a controller of a sunset panel (manufactured by Evening Panel Systems Co., Ltd.), and a pulse voltage of 15 V to an oscillation transducer and a Rayleigh wave (frequency of 5.53 MHz) are supplied. ) In the condition of the distance between the transmitting and receiving transducers of 25 mm, the change of the received signal strength depending on the thickness h of the diffraction grating was measured. The results are shown in Figure 3. The dotted line in Fig. 3 represents the minimum signal strength level to be driven. As is evident from Fig. 3, it is difficult to obtain a high signal intensity when the grating thickness h is less than 15 microns.

Example 2

Except for replacing the coupling length L of the thickness h and the diffraction grating of the diffraction grating, where to prepare a glass substrate in the same manner as in Example 1 was examined the relationship between h ² L and the signal strength, the results shown in FIG. 4 Was. As is evident from FIG. 4, when the thickness is 75 μμπι ² · mm or more, the touch panel can be practically operated as a touch panel.

Example 3

A glass substrate was produced in the same manner as in Example 1, except that the ratio W / P between the wire diameter W of the grating constituting the diffractive acoustic wave transducer and the distance between lines (pitch) P was changed. As a result, the result shown in FIG. 5 was obtained. Figure 5 As can be seen, the ratio W / P = 0.4 to 0.95 enables practical operation as a sunset panel.

Example 4

Coupling length of the diffractive acoustic wave transducin The L, except for replacing the density P of the material constituting the grid thickness] !, grid, to prepare a glass substrate in the same manner as in Example 1, and ph ² L and signal strength When the relationship was examined, the result shown in FIG. 6 was obtained. As is apparent from FIG. 6, in ph ² L is ^{^{3. 5 X 10 6 μπι 2 ·}} mm · kg / m 3 or more, it is practically operable as evening Tsuchipane Le.

Claims

The scope of the claims

1. (a) a substrate having a surface; (b) an acoustic wave transformer for coupling with a first wave as a bulk wave propagating through the substrate along an axis intersecting the surface; (c) A second acoustic wave having a mode of a converted wave having a large amount of energy at the surface and propagating along an axis parallel to the surface; and a diffractive acoustic wave for coupling the first wave with the second wave. A transducer, and (d) means for detecting a perturbation in energy of the second wave, wherein a thickness h of a grating constituting the diffractive acoustic wave transducer is 15 to 39 μπι. Acoustic contact detection device.

2. A device provided with the configurations (a) to (d) according to claim 1, wherein a ratio W / P of a diameter W and a pitch P of a grating constituting the diffractive acoustic wave transducer is 0.4 to Acoustic contact detection device that is 0.95.

3. A device comprising the configurations (a) to (d) according to claim 1, wherein the coupling length of the diffractive acoustic wave transducer is L, and the thickness of the grating constituting the diffractive acoustic wave transducer is h. When h ² L is greater than or equal to 75 μμπι ² · mm, an acoustic contact detector.

4. An apparatus comprising the configuration (a) to (d) according to claim 1, wherein the coupling length of the diffractive acoustic wave transducer is L, the thickness of the grating constituting the diffractive acoustic wave transducer is h, and the grating is when the density of the material constituting the p-a, ph ² L is 3. 5 X 10 ⁶ μ m acoustic touch sensing apparatus is ² · mm · kg / m ³ or more.

5. The following configuration:

(a) an acoustic wave transducer coupled to a bulk wave having a propagation axis crossing the substrate surface in the substrate;

(b) a diffractive acoustic wave transducer formed in the vicinity of the surface for converting acoustic wave energy of a bulk wave into a wave propagating along an axis parallel to the surface; A diffractive acoustic wave transducer according to any of paragraphs; and (C) A substrate for an acoustic detection device having means for detecting the converted acoustic wave energy with respect to the location of the perturbation.