JPH1055246A - Ultrasonic touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the ultrasonic touch panel which is driven with low power consumption, simple in way of supporting, and easy to use and decides a contact position with high sensitivity. SOLUTION: When ultrasonic wave transmitting and receiving means X and Y which have mutually orthogonal propagation paths input electric signals from inter digital electrodes TXi and TYi , a surface acoustic wave is excited nearby the plate surface of a piezoelectric ceramic plate 1 where interdigital electrodes are provided and propagated to a nonpiezoelectric plate 2, and then outputted as electric signals from interdigital electrodes RX and RY. When the intersection part of propagation paths UXi and UYi on the nonpiezoelectric plate 2 is touched, their output electric signals are attenuated or ceased to exist, so the contact position can be decided.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic wave that specifies the coordinates of the position at which the pen tip of an input pen contacts a non-piezoelectric plate by fixing the non-piezoelectric plate to a piezoelectric plate having interdigital electrodes. Related to touch panels.

2. Description of the Related Art Conventional touch panels mainly include a method using a resistive film and a method using ultrasonic waves. The method using a resistive film is based on the fact that the resistance value of the transparent conductive film changes when it comes into contact with the transparent conductive film (resistive film). There is a problem in terms of properties. In addition, there is a disadvantage that it is difficult to increase the area of the panel. The method using ultrasonic waves utilizes the fact that surface acoustic waves are attenuated by contact with a non-piezoelectric plate in which surface acoustic waves have been excited in advance. Conventional methods of exciting a surface acoustic wave to a non-piezoelectric plate include a method of indirectly exciting a wedge-shaped transducer using a bulk wave oscillator, and a method of directly exciting a piezoelectric thin film transducer. The wedge-shaped transducer is used for non-destructive inspection or the like by ultrasonic waves, but is used only in a relatively low frequency region due to the problem of machining accuracy of the wedge angle. Piezoelectric thin film transducer is ZnO
A method in which a piezoelectric thin film is deposited on a substrate and a surface acoustic wave is excited by an interdigital electrode. Since the interdigital electrode shows various transmission characteristics, it is used as a high-frequency device, but is limited to the UHF and VHF bands. In addition, there is a problem in workability and mass productivity. Thus, the response time, sensitivity, durability, work accuracy, workability,
There are problems in terms of mass productivity and ease of use, and the operating frequency range is also limited. Therefore, an ultrasonic touch panel that solves these problems has been filed by the present inventor in Japanese Patent Application No. 4-218336. This ultrasonic touch panel is provided with at least two ultrasonic devices comprising a piezoelectric thin plate and an interdigital electrode on one plate surface of a non-piezoelectric plate, and efficiently generates a surface acoustic wave with low power consumption on the non-piezoelectric plate. Can be excited on the surface. Therefore, if a finger or an object comes into contact with a surface acoustic wave propagation path on one surface of the non-piezoelectric plate, the surface acoustic wave is attenuated or eliminated, so that contact with the finger or the object is sensed. However, in this ultrasonic touch panel, when a surface acoustic wave is excited near the surface of a non-piezoelectric plate, a large percentage of the surface acoustic wave leaks into the non-piezoelectric plate, and therefore, there is only a problem in power consumption. Rather, we needed to devise ways to support the non-piezoelectric plate and suppress unnecessary signals. Further, the efficiency of converting a surface acoustic wave excited near the surface of the non-piezoelectric plate into an electric signal is poor.

The conventional touch panel not only has problems in response time, sensitivity, durability, work precision, workability, mass productivity, ease of use, and the like.
There were also problems with power consumption, support methods, generation of unnecessary signals, and the like. An object of the present invention is to provide an ultrasonic touch panel that is excellent in workability, durability and mass productivity, driven with low power consumption, has a short response time, and is easy to use.

According to the first aspect of the present invention, there is provided an ultrasonic touch panel comprising at least two ultrasonic transmitting / receiving means.
And a Y, a piezoelectric plate, a non-piezoelectric plate, and an information processing unit connected to the ultrasonic wave transmitting and receiving means X and Y, wherein each of the ultrasonic wave transmitting and receiving means is N
A set of interdigital electrodes T _i (i = 1, 2,..., N), interdigital electrodes R and N switches W _i (i = 1, 2,...)
.., N), the interdigital electrodes T _i and R are provided on one plate surface of the piezoelectric plate, and the lower end surface of the non-piezoelectric plate is provided with the respective interdigital electrodes on the one plate surface of the piezoelectric plate. The output terminal of the switch W _i is connected to the input terminal of the interdigital electrode T _i , and the interdigital electrode T _i is connected to the electrode period length p of the interdigital electrode T _i. substantially by inputting an electric signal E _T of the corresponding frequency, exciting the surface acoustic wave having a wavelength substantially equal to the interdigital periodicity p wherein in the vicinity of the surface of the one plate surface of the piezoelectric plate, the elastic in The surface acoustic wave is propagated to the upper end surface of the non-piezoelectric plate, and the surface acoustic wave propagated to the upper end surface of the non-piezoelectric plate is a 0th-order mode and a first-order or higher-order mode wave,
The phase velocity of the zero-order mode surface acoustic wave is substantially equal to the velocity of the Rayleigh wave propagating to the piezoelectric plate in an electrically short-circuit state, and the phase velocity of the first-order or higher-order surface acoustic wave is higher. Is substantially equal to the speed of the Rayleigh wave propagating to the piezoelectric plate in an electrically open state, and the interdigital transducer R transmits the surface acoustic wave propagated to the upper end surface of the non-piezoelectric plate to the piezoelectric plate. The surface acoustic wave propagated near the surface of the one plate surface and propagated near the surface of the one plate surface of the piezoelectric plate is converted into an electric signal E having a frequency substantially corresponding to the electrode period length p of the interdigital transducer R. Convert to _R and output,
The surface acoustic wave propagated in the vicinity of the surface of the one plate surface of the piezoelectric plate is a wave of a zero-order mode and a first-order or higher-order mode, the wavelength of which is substantially equal to the electrode period length p, and The phase velocity of the surface acoustic wave in the mode is almost equal to the velocity of the Rayleigh wave propagating to the piezoelectric plate in an electrically short-circuit state, and the phase velocity of the surface acoustic wave in the first or higher order mode is an electric wave. The velocity of the Rayleigh wave propagating in the piezoelectric plate alone in a substantially open state is substantially equal to the velocity, the thickness of the piezoelectric plate is approximately three times or more the electrode period length p, and the thickness d of the non-piezoelectric plate is The phase velocity of the surface acoustic wave propagating through the non-piezoelectric plate alone is smaller than the electrode period length p, and is smaller than the phase velocity of the surface acoustic wave propagating through the piezoelectric plate alone. sequentially intermittently at a predetermined cycle _i, pre Detecting the magnitude of the electrical signal E _R, the magnitude of said electrical signal that the pen tip of the input pen on the upper end face is in contact E _R of the non-piezoelectric plate is determined by the attenuation or disappearance, the electrical the magnitude of the signal E _R to identify the contact position by identifying the switch W _i which is connected when the attenuated or abolished. 3. The ultrasonic touch panel according to claim 2, wherein the ultrasonic wave transmitting / receiving means X has a surface acoustic wave propagation path U _Xi (i = 1, 2,..., N) between the interdigital transducers T _i and R. ) And the surface acoustic wave propagation path U _Yi (i = 1, 2,..., N) between the interdigital transducers T _i and R in the ultrasonic wave transmitting / receiving means Y are orthogonal to each other. . In the ultrasonic touch panel according to claim 3, the propagation paths U _Xi are adjacent to each other or partially overlap each other, and the propagation paths U _Yi are adjacent to each other or partially overlap each other. 5. The ultrasonic touch panel according to claim 4, wherein an oscillator H _i (i = 1, 2,..., N) having the propagation paths U _Xi and U _Yi as delay elements is configured, and the ultrasonic transmission / reception is performed. input of the switch W _i in unit X, the are connected via an amplifier a _Y to the output terminal of the IDT R in ultrasonic transmitter unit Y, the said switch in the ultrasonic transmitter means Y input of W _i, the are connected via an amplifier a _X to an output terminal of the IDT R in ultrasonic transmitter unit X, the oscillator H _i signal loops of the ultrasonic transmitter means wherein the X switches W _i, the channel U _Xi, the amplifier A _X, and the ultrasonic transmitter means Y
The switch W _i, the channel U _Yi in, comprising the amplifier A _Y. The ultrasonic touch panel according to claim 5, wherein at least two ultrasonic wave transmitting and receiving means X and Y,
An ultrasonic touch panel comprising a piezoelectric plate, a non-piezoelectric plate, and an information processing unit connected to the ultrasonic wave transmitting / receiving means X and Y, wherein each of the ultrasonic wave transmitting / receiving means has an interdigital electrode T
And the interdigital transducers R _i (i = 1, 2,..., N), the interdigital transducers T and R _i are provided on one surface of the piezoelectric plate, and the lower end surface of the non-piezoelectric plate is The interdigital transducer is fixed to the one plate surface of the piezoelectric plate via the interdigital transducer, and the interdigital transducer T is
By being substantially the interdigital periodicity p inputs the electric signal E _T of the corresponding frequency, the surface acoustic wave having a wavelength substantially equal to the interdigital periodicity p wherein in the vicinity of the surface of the one plate surface of said piezoelectric plate When the surface acoustic wave is excited, the surface acoustic wave propagates to the upper end surface of the non-piezoelectric plate, and the surface acoustic wave propagated to the upper end surface of the non-piezoelectric plate is a 0th-order mode and a first-order or higher-order mode wave. The phase velocity of the surface acoustic wave in the zero-order mode is substantially equal to the velocity of the Rayleigh wave propagating to the piezoelectric plate alone in an electrically short-circuit state, and the phase velocity of the surface acoustic wave in the first-order or higher-order mode is higher. The speed is substantially equal to the speed of the Rayleigh wave propagating to the piezoelectric plate in an electrically open state, and the interdigital transducer R _i transmits the surface acoustic wave propagated to the upper end face of the non-piezoelectric plate to the piezoelectric plate. Propagated near the surface of the one plate surface of the plate The surface acoustic wave propagated in the vicinity of the surface of the one plate surface of the piezoelectric plate is applied to the IDTs R
An electric signal E _{Ri having} a frequency substantially corresponding to the electrode period length p of _i
(I = 1, 2,..., N) and output, and the surface acoustic wave propagated near the surface of the one plate surface of the piezoelectric plate is a zero-order mode and a first-order or higher-order mode. The wavelength of which is substantially equal to the electrode period length p, and the phase velocity of the zero-order mode surface acoustic wave is substantially equal to the velocity of the Rayleigh wave propagating to the piezoelectric plate alone in an electrically short-circuited state. The phase velocity of the first or higher order surface acoustic wave is substantially equal to the velocity of the Rayleigh wave propagating to the piezoelectric plate in an electrically open state, and the thickness of the piezoelectric plate is equal to the electrode period. And the thickness d of the non-piezoelectric plate is smaller than the electrode period length p, and the phase velocity of the surface acoustic wave propagating in the non-piezoelectric plate alone is Is smaller than the phase velocity of the surface acoustic wave, Detecting the magnitude of the electrical signal E _Ri, the size of the non-piezoelectric plate the electric signal that the pen tip of the input pen in contact with the upper end face of the E _Ri is determined by the attenuation or disappearance, attenuated or specifying the contact position by specifying the interdigital electrodes R _i corresponding to disappear electric signal E _Ri. Ultrasonic touch panel as set forth in claim 6, wherein the channel U _Xi (i = 1 of the surface acoustic wave between the IDT T and R _i in the ultrasonic transmitter means X,
2, ......, N) and the propagation path U of the surface acoustic wave between the IDT T and R _i in the ultrasonic transmitter means Y
_Yi (i = 1, 2,..., N) are orthogonal to each other.
The ultrasonic touch panel according to claim 7, wherein:
_Xi are adjacent to each other or partially overlap each other,
The propagation paths U _Yi are adjacent to each other or partially overlap each other. The ultrasonic touch panel according to claim 8,
An oscillator H having the propagation path U _Y1 of the propagation path U _Yi as a delay element is formed, and the output terminal of the interdigital transducer R ₁ corresponding to the propagation path U _Y1 is connected to the ultrasonic wave transmitting / receiving means X.
And wherein the Y is connected via an amplifier AMP to the input terminal of the IDT T, signal loop of the oscillator H, the IDT T corresponding to the channel U _Y1, the channel U _Y1, comprising the interdigital electrode R ₁ and the amplifier AMP corresponding to the channel U _Y1. In the ultrasonic touch panel according to the ninth aspect, the other surface of the piezoelectric plate is supported by a support substrate. In the ultrasonic touch panel according to the tenth aspect, the piezoelectric plate is made of a piezoelectric ceramic, and a direction of a polarization axis of the piezoelectric ceramic is parallel to a thickness direction of the piezoelectric ceramic.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An ultrasonic touch panel according to the present invention
It has a simple structure consisting of at least two ultrasonic wave transmitting / receiving means X and Y, a piezoelectric plate, a non-piezoelectric plate, and an information processing unit connected to the ultrasonic wave transmitting / receiving means X and Y. Two structures are provided as ultrasonic wave transmitting / receiving means. The first structure is that each ultrasonic transmitting / receiving means has N sets of IDTs.
_i (i = 1, 2,..., N), ID electrodes R and N
The switch W _i (i = 1, 2,..., N). In this case, the interdigital electrodes T _i and R are provided on one plate surface of the piezoelectric plate, and the lower end surface of the non-piezoelectric plate is fixed thereon. The output terminal of the switch W _i is connected to the input end of the interdigital transducer T _i. By employing a structure to be input to the IDT T _i an electrical signal E _T approximately corresponding frequency interdigital periodicity p of IDT T _i, who IDT T _i of the piezoelectric plate is provided A surface acoustic wave having a wavelength substantially equal to the electrode period length p of the interdigital transducer T _i is excited near the surface of the plate surface of the non-piezoelectric plate, and the surface acoustic wave can be propagated to the upper end surface of the non-piezoelectric plate. At this time, the surface acoustic waves of the zero-order mode and the first-order and higher-order modes are propagated to the non-piezoelectric plate. A structure in which the phase velocity of the zero-order surface acoustic wave is almost equal to the velocity of the Rayleigh wave propagating to the piezoelectric plate in an electrically short-circuit state, and the phase of the first-order or higher-order surface acoustic wave speed conversion by employing a substantially equal such a structure the Rayleigh wave velocity propagating in the piezoelectric plate alone in electrically open state, the electrical energy applied from interdigital transducer T _i is the surface acoustic wave In addition to increasing the degree of noise reduction, it is possible to eliminate reflections and the like caused by acoustic impedance mismatch at the interface between the piezoelectric plate and the non-piezoelectric plate. Further, a nearly 3-fold or more interdigital periodicity p of IDT T _i the thickness of the piezoelectric plate, the thickness d of the non-piezoelectric plate smaller than the electrode period length p, which propagates in a non-piezoelectric plate alone elasticity By adopting a material whose phase velocity of the surface wave is smaller than the phase velocity of the surface acoustic wave propagating to the piezoelectric plate alone as the non-piezoelectric plate, the ultrasonic wave does not leak inside the piezoelectric plate, A surface acoustic wave can be efficiently propagated. Therefore, not only low power consumption driving is enabled, but also the support of the piezoelectric plate becomes easy. At this time, it is possible to support a portion of the piezoelectric plate other than the vicinity of the surface of the plate surface on which the interdigital electrodes are provided. IDT
By adopting a structure in which _i and R are paired one-to-one with each other so that the directional axes of the transmission and reception of the surface acoustic waves are common, the surface acoustic waves propagated to the upper end surface of the non-piezoelectric plate Can be output from the interdigital electrode R as an electric signal E _R. At this time, the surface acoustic wave propagated to the non-piezoelectric plate is once propagated to the vicinity of the surface of the plate surface on which the interdigital electrodes of the piezoelectric plate are provided, and then to the interdigital electrode R.
Is output from the interdigital transducer R as an electric signal E _R having a frequency substantially corresponding to the electrode cycle length p. The surface acoustic wave propagated to the piezoelectric plate is a wave of a zero-order mode and a first-order or higher-order mode. The electrode period length p is set so that the wavelength of the surface acoustic wave is substantially equal to the electrode period length p, and the phase velocity of the zero-order mode surface acoustic wave propagates to the piezoelectric plate in an electrically short-circuit state. A structure in which the velocity is almost equal to the Rayleigh wave velocity and the phase velocity of the surface acoustic wave of the first or higher order mode is approximately equal to the velocity of the Rayleigh wave propagating to the piezoelectric plate in an electrically open state. By employing a simple structure, the surface acoustic wave propagated to the piezoelectric plate can be efficiently output as an electric signal E _R from the interdigital transducer R. In addition, it is possible to eliminate reflections or the like caused by acoustic impedance mismatch at the interface between the piezoelectric plate and the non-piezoelectric plate. Further, the thickness of the piezoelectric plate is set to be approximately three times or more the electrode period length p of the interdigital transducer R, the thickness d of the non-piezoelectric plate is made smaller than the electrode period length p, and the elastic surface propagating to the non-piezoelectric plate alone is formed. By adopting a non-piezoelectric plate as a non-piezoelectric plate, a material whose wave phase velocity is smaller than the phase velocity of the surface acoustic wave propagating to the piezoelectric plate alone, the ultrasonic wave does not leak inside the piezoelectric plate and propagates to the non-piezoelectric plate. The generated surface acoustic wave can be efficiently output from the interdigital electrode _R as an electric signal E _R. Therefore, not only low power consumption driving is enabled, but also the support of the piezoelectric plate becomes easy. At this time, it is possible to support a portion of the piezoelectric plate other than the vicinity of the surface of the plate surface on which the interdigital electrodes are provided. If the tip of the input pen makes contact between the interdigital transducers T _i and R on the upper end surface of the non-piezoelectric plate, the propagation path of the surface acoustic wave is cut off, and accordingly the signal is output to the interdigital transducer R. The electric signal E _R also disappears or attenuates. And functions of the information processing unit detects the magnitude of the electric signal E _R, a function of the magnitude of the electric signal E _R that nib on the upper end surface of the non-piezoelectric plate are in contact is determined by the attenuation or disappearance By having
Contact with the upper end surface of the non-piezoelectric plate is sensed in a short response time. Furthermore, the functions of the information processing unit is intermittently by sequentially predetermined cycle switches W _i, by the magnitude of the electric signal E _R to identify the switch W _i which is connected when attenuation or disappearance of non-piezoelectric plate By providing the function of specifying the contact position on the upper end surface, the contact position on the upper end surface of the non-piezoelectric plate can be known. For example, by contacting the upper end surface of the non-piezoelectric plate, the magnitude of the electric signal E _R disappears, and if the switch W ₅ is connected at that time, the surface acoustic wave corresponding to the switch W ₅ It can be seen that the contact position is on the propagation path. The propagation path U _Xi (i of the surface acoustic wave between the interdigital transducers T _i and R in the ultrasonic wave transmitting / receiving means X
= 1, 2,..., N) and the surface acoustic wave propagation path U _Yi between the interdigital transducers T _i and R in the ultrasonic wave transmitting / receiving means Y.
(I = 1, 2,..., N) are orthogonal to each other, so that when the upper end surface of the non-piezoelectric plate is contacted with the pen tip of the input pen, the coordinates of the contact position are represented by each ultrasonic wave. It can be specified from the magnitude of the electric signal E _R output from the transmitting / receiving means. That is, the channel U _Xi and U _Yi coordinates of the contact position to correspond to two-dimensional coordinates of the X-axis and Y-axis respectively, the channel U _Xi and U the contact position
If it is made to correspond to the intersection with _Yi , the coordinates of the intersection are calculated. In addition, by adopting a structure in which the propagation paths U _Xi are adjacent to each other or partially overlap each other and the propagation paths U _Yi are adjacent to each other or partially overlap each other, the contact position on the upper end surface of the non-piezoelectric plate can be reduced. It is possible to specify more precisely. Switch W in X-axis direction
By adopting a method of making a round of the switch W _i in the Y-axis direction while one of the _i is connected, the contact position can be easily specified. For example, a propagation path U _X3 between the interdigital transducer T ₃ and the interdigital transducer R in the X-axis direction, and a propagation path U between the interdigital transducer T ₅ and the interdigital transducer R in the Y-axis direction.
_If the intersection with _Y5 is touched with the pen tip, the magnitude of the electric signal E _{R in} the X-axis direction is attenuated or eliminated only when the switch W ₃ in the X-axis direction is connected, and at the same time, the switch W in the Y-axis direction is turned off. Only when ₅ is connected, the magnitude of the electric signal E _{R in} the Y-axis direction attenuates or disappears. Thus, the propagation path U
It is found that the intersection of _X3 and _UY5 is in contact.
The switches W _i in the ultrasonic wave transmitting and receiving means X and Y are respectively referred to as a switch W _Xi and a switch W _Yi, and the input terminal of the switch W _Xi is connected to the output terminal of the interdigital transducer R in the ultrasonic wave transmitting and receiving means Y via an amplifier A _Y. Connect and switch W
By employing a structure for connecting via the amplifier A _X to the output end of the IDT R input terminal of the _Yi in ultrasonic transmitter unit X, oscillator H _i for the channel U _Xi and U _Yi as delay elements (I = 1, 2,..., N). At this time, the signal loop of the oscillator H _i consists of switches W _Xi, channel U _Xi, amplifier A _X, the switch W _Yi, channel U _Yi and amplifier A _Y. In this way,
The simplification of the circuit configuration further promotes the reduction in size and weight of the device, and enables driving at low voltage with low power consumption. The second structure of the ultrasonic wave transmitting / receiving means is such that each ultrasonic wave transmitting / receiving means has an interdigital electrode T and an interdigital electrode R
_i (i = 1, 2,..., N). In this case, IDT T and R _i are provided on one plate surface of the piezoelectric plate, the lower end surface of the non-piezoelectric plate thereon is fixed. By adopting a structure for inputting an electric signal E _T of a frequency substantially corresponding to the interdigital periodicity p of IDT T in the IDT T, the plate surface towards the IDT T of the piezoelectric plate is provided A surface acoustic wave having a wavelength substantially equal to the electrode period length p of the interdigital transducer T is excited near the surface of
The surface acoustic wave can be propagated to the upper end surface of the non-piezoelectric plate. At this time, the surface acoustic waves of the zero-order mode and the first-order and higher-order modes are propagated to the non-piezoelectric plate. A structure in which the phase velocity of the zero-order surface acoustic wave is almost equal to the velocity of the Rayleigh wave propagating to the piezoelectric plate in an electrically short-circuit state, and the phase of the first-order or higher-order surface acoustic wave By adopting a structure in which the speed is substantially equal to the speed of the Rayleigh wave propagating to the piezoelectric plate in an electrically open state, the electric energy applied from the interdigital transducer T is converted into a surface acoustic wave. In addition to increasing the degree of reflection, it is possible to eliminate reflection and the like caused by acoustic impedance mismatch at the interface between the piezoelectric plate and the non-piezoelectric plate. Further, the thickness d of the piezoelectric plate is set to be approximately three times or more the electrode period length p of the interdigital transducer T, the thickness of the non-piezoelectric plate is made smaller than the electrode period length p, and the elastic surface propagating to the non-piezoelectric plate alone. By using a substance whose phase velocity is smaller than the phase velocity of the surface acoustic wave propagating to the piezoelectric plate as a non-piezoelectric plate, the efficiency of the non-piezoelectric plate can be improved without leaking ultrasonic waves inside the piezoelectric plate. A surface acoustic wave can be propagated well. By the interdigital electrodes T and R _i are directional axes of transmission and reception waves of the surface acoustic wave to employ a structure arranged to be in common, interdigital electrodes surface acoustic waves are propagated to the upper end surface of the non-piezoelectric plate R _i can be output as an electric signal E _Ri . At this time, the non-after surface acoustic waves are propagated once each interdigital transducer of the piezoelectric plate which is propagated in the vicinity of the surface of the plate surface of the person who provided the piezoelectric plate, the electrode periodicity of IDT R _i p Electrode R as an electric signal E _{Ri at} a frequency substantially corresponding to
Output from _i . The surface acoustic wave propagated to the piezoelectric plate is a wave of a zero-order mode and a first-order or higher-order mode. The electrode period length p is set so that the wavelength of the surface acoustic wave is substantially equal to the electrode period length p, and the phase velocity of the zero-order mode surface acoustic wave propagates to the piezoelectric plate in an electrically short-circuit state. A structure in which the velocity is almost equal to the Rayleigh wave velocity and the phase velocity of the surface acoustic wave of the first or higher order mode is approximately equal to the velocity of the Rayleigh wave propagating to the piezoelectric plate in an electrically open state. by adopting such structure, it is possible to output a surface acoustic wave propagating on the piezoelectric plate as efficiently electric signal E _Ri from IDT R _i.
In addition, it is possible to eliminate reflections or the like caused by acoustic impedance mismatch at the interface between the piezoelectric plate and the non-piezoelectric plate. Furthermore, a nearly three-fold or more interdigital periodicity p of interdigital electrodes R _i the thickness of the piezoelectric plate, the thickness d of the non-piezoelectric plate smaller than the electrode period length p, which propagates in a non-piezoelectric plate alone elasticity By adopting a material whose phase velocity of the surface wave is smaller than the phase velocity of the surface acoustic wave propagating to the piezoelectric plate alone as the non-piezoelectric plate, the ultrasonic wave does not leak inside the piezoelectric plate, the surface acoustic wave which is propagated can be output from the interdigital electrode R _i as efficiently electric signal E _Ri. Upon contact between the interdigital transducers T and R _i of the upper end surface of the non-piezoelectric plate with the pen tip of the input pen, because the propagation path of the surface acoustic wave is blocked, is outputted to the interdigital electrodes R _i with it The electrical signal E _Ri also disappears or attenuates. The information processing unit has a function of detecting the magnitude of the electric signal E _Ri and a function of determining that the tip of the pen touches the upper end surface of the non-piezoelectric plate by attenuating or eliminating the magnitude of the electric signal E _Ri. With the provision, the contact with the upper end surface of the non-piezoelectric plate is sensed in a short response time. Further, the information processing unit has a function of specifying the contact position by specifying the interdigital electrode R _i corresponding to the attenuated or eliminated electric signal E _Ri , so that the contact position on the upper end surface of the non-piezoelectric plate is provided. I understand. In the ultrasonic wave transmitting / receiving means X, the surface acoustic wave propagation path U _Xi between the interdigital transducers T and R _i (i =
1, 2,..., N) and the surface acoustic wave propagation path U between the interdigital transducers T and R _i in the ultrasonic wave transmitting / receiving means Y.
By adopting a structure in which _Yi (i = 1, 2,..., N) is orthogonal to each other, when the upper end surface of the non-piezoelectric plate is contacted with the pen tip of the input pen, the coordinates of the contact position are superimposed. It can be specified from the magnitude of the electric signal E _Ri output from the sound wave transmitting / receiving means. That is, if the coordinates of the contact position correspond to the two-dimensional coordinates with the propagation paths U _Xi and U _Yi as the X axis and the Y axis, respectively, and the contact position corresponds to the intersection of the propagation paths U _Xi and U _Yi. , The coordinates of the intersection are calculated. Further, by adopting a structure in which the propagation paths U _Xi are adjacent to each other or partially overlap each other, and the propagation paths U _Yi are adjacent to each other or partially overlap each other, the contact position on the upper end surface of the non-piezoelectric plate can be reduced. It is possible to specify more precisely. A structure in which the output end of the interdigital transducer R ₁ corresponding to the propagation path U _Y1 of the propagation path U _Yi is connected to the input ends of the respective interdigital transducers T of the ultrasonic wave transmitting / receiving means X and Y via the amplifier AMP. By adopting the oscillator H, the propagation path U _Y1 is used as a delay element.
Can be configured. At this time, the signal loop of the oscillator H includes the IDT T corresponding to the propagation path U _Y1 and the propagation path U
_Y1, consisting of interdigital transducers R ₁ and an amplifier AMP corresponding to the propagation path U _Y1. Since the circuit configuration is simplified in this way, the device can be further reduced in size and weight, and can be driven with low power consumption and low voltage. In the ultrasonic touch panel of the present invention, each interdigital electrode of the piezoelectric plate is provided by employing a piezoelectric ceramic as the piezoelectric plate and adopting a structure in which the direction of the polarization axis of the piezoelectric ceramic is parallel to the thickness direction. Efficiently excites a surface acoustic wave near the surface of the plate surface that is applied and propagates it to the upper end surface of the non-piezoelectric plate, and efficiently converts the surface acoustic wave propagated to the upper end surface of the non-piezoelectric plate to the surface of the piezoelectric plate. is propagated in the vicinity of the surface of the plate surface of the person who provided the respective interdigital electrodes can be output as an electric signal from the IDT R or R _i.

FIG. 1 shows a first embodiment of an ultrasonic touch panel according to the present invention.
It is sectional drawing which shows an Example. In this embodiment, the piezoelectric ceramic plate 1 is used.
Non-piezoelectric plate 2, support substrate 3, drive unit 4, ultrasonic wave in X-axis direction
From the transmitting and receiving means X and the ultrasonic transmitting and receiving means Y in the Y-axis direction
Become. The ultrasonic wave transmitting / receiving means X is an interdigital electrode T_Xi(I =
1, 2,..., 8), interdigital electrode R_X, Amplifier A_XAnd
And switch W_Xi(I = 1, 2,..., 8). Super
The sound wave transmitting / receiving means Y is an interdigital electrode T_Yi(I = 1,2, ...
..., 8), interdigital electrode R_Y, Amplifier A_YAnd switches
W_Yi(I = 1, 2,..., 8). Figure 1 shows the piezoelectric
Porcelain plate 1, Non-piezoelectric plate 2, Support substrate 3, Driving unit 4, Ultra
Only the sound wave transmitting / receiving means X is illustrated. IDT
_Xi, T_Yi, R_XAnd R_YConsists of an aluminum thin film. Pressure
The electromagnetic plate 1 is made of TDK 101A (1.5 mm thick).
Product name). The non-piezoelectric plate 2 is made of glass, fluororesin or
It is made of a polymer compound such as a ril resin, and has a thickness of 0.15
mm. Each interdigital electrode is provided on the piezoelectric ceramic plate 1.
Further, a non-piezoelectric plate 2 is provided thereon. Non
When the piezoelectric plate 2 is made of glass or the like, an approximately 20 μm thick
It is fixed on the piezoelectric ceramic plate 1 by a
When the electric plate 2 is made of fluororesin or acrylic resin,
The piezoelectric plate 2 is applied directly on the piezoelectric ceramic plate 1. Piezoelectric
The lower part of the porcelain plate 1 is fixed and supported on a support substrate 3.
You. FIG. 2 shows the IDT of FIG._XiFIG.
You. IDT_YiBordered electrode T_XiSimilar structure to
Having. Interdigital electrode R_XAnd R_YIDT
_XiHas the same structure except that the length of the electrode fingers is different.
Has structure. IDT_XiHas 10 pairs of electrode fingers
The electrode period length p is 460 μm, and the overall shape is
Form a polygon. FIG. 3 is a partial oblique view of the ultrasonic touch panel of FIG.
FIG. In FIG. 3, the interdigital electrode T_X1, T_X2, T_Y1You
And only the piezoelectric ceramic plate 1 are shown. FIG. 4 is a diagram of FIG.
It is a top view of a sound wave touch panel. In FIG. 4, a piezoelectric ceramic plate
1. IDT_Xi, T_Yi, R_XAnd R_YOnly drawn
Have been. FIG. 5 is a driving circuit of the ultrasonic touch panel of FIG.
FIG. The drive unit 4 includes a voltage doubler rectifier 5 and a comparator.
Data unit 6 and an information processing unit 7. Switch W_XiHa sui
Switch W_Xi-1And switch W_Xi-2And the switch W
_YiIs switch W_Yi-1And switch W_Yi-2Consists of S
Switch W_XiAnd W_YiOutput terminals are ID
T_XiAnd T_YiIs connected to the input terminal of Switch W
_Xi-1Of the amplifier A_YThrough the interdigital electrode R_YOut of
Switch W_Yi-1Of the amplifier A_X
Through the interdigital electrode R_XConnected to the output end of the
In the driving circuit of FIG._XiTelegraph from
No. E_TIs input, the electric signal E_TOut of frequency
Drooping electrode T_XiOf the center frequency indicated by
Only the electric signal is converted to a surface acoustic wave, and the piezoelectric ceramic plate 1
Through the vicinity of the surface of the plate surface on which the
And the surface acoustic wave is transmitted to the upper end surface of the non-piezoelectric plate 2.
Carried. Surface acoustic wave propagated to the upper end surface of non-piezoelectric plate 2
Interdigital electrode R_XThe center frequency shown by
Only the surface acoustic wave of frequency is an electric signal E_RIs converted to
Drooping electrode R_XOutput from Electric signal E_RIs the amplifier A
_XA part of the amplified electric signal is amplified by
Switch W_Yi-1Electrode T through the_YiIs entered into
The rest is via the voltage doubler rectifier 5 and the comparator 6
After being sent to the information processing section 7, the switch W_Xi-2And W
_Yi-2Electrode T through the_XiAnd T_YiEntered in
You. Electric signal interdigital electrode T_YiEntered into the electricity
Signals are converted to surface acoustic waves in the same way as in the X-axis direction
The piezoelectric ceramic plate 1 is provided with each interdigital electrode.
Propagates near the surface of the plate surface, and its surface acoustic wave is
After being propagated to the upper end surface of the piezoelectric plate 2,_YOr
Output as an electrical signal from the amplifier A_YAmplified by
It is. A part of the amplified electric signal is_Xi-1
Electrode T through the_XiAnd the rest is double voltage
To the information processing unit 7 via the rectifier 5 and the comparator 6
After being sent, switch W_Xi-2And W_Yi-2Through
Reed-shaped electrode T_XiAnd T_YiIs input to Like this
And interdigital electrodes T_XiAnd R_XOf surface acoustic waves between
Road U_Xi(I = 1, 2,..., 8) and IDT
_YiAnd R_YSurface acoustic wave propagation path U between_Yi(I = 1,
Oscillator H having delay elements of 2,..., 8)_i(I = 1,
2,..., N). At this time, the oscillator H
_iThe signal loop of switch W_Xi-1, Propagation path U_{X i},amplifier
A_X, Switch W_Yi-1, Propagation path U_YiAnd amplifier A_YFrom
Become. Therefore, since the circuit configuration is simplified, the device
Smaller and lighter are further promoted, and low power consumption and low power consumption
Driving with pressure becomes possible. The information processing section 7 has the following functions.
I do. First, switch W_XiAnd W_YiThe given
Intermittent in the cycle, secondly, the electric signal E_RThe size of
Third, the upper end surface of the non-piezoelectric plate 2 (hereinafter referred to as
Touching the pen tip of the input pen
Electric signal E_RIs reduced or disappears.
Fourth, the electric signal E_RThe size of the decay
Or the switch W that was connected when it disappeared_Xiand
W_YiSpecifying the contact position by specifying
You. Switch W_XiAnd W_YiIntermittently at predetermined intervals
Switch W_XiWhile connecting one of the
And switch W_YiIs used. Ma
Switch W_Xi-1And the corresponding switch W_Xi-2Is
Always in the same intermittent state, switch W_Yi-1And corresponding
Switch W_Yi-2Are always in the same intermittent state. Propagation path
U_XiAnd U_YiIf the pen tip touches the intersection with
If the propagation path U_X3And U_Y5When contacting the intersection with
Switch W_X3Is connected only when the electric signal E in the X-axis direction is_R
At the same time as the magnitude of_Y5
Is connected only when the electric signal E in the Y-axis direction is_RSize of
Decay or disappear. Thus, the propagation path U_X3When
U_Y5Is found to be in contact with the intersection of Toes
The electrical signal E_RWhen the size of the
Switch W which was continued_XiAnd W_YiTo identify
Thus, it is possible to specify the contact position. Shown in FIG.
As shown, each interdigital electrode forms a parallelogram
Therefore, the propagation path U_XiAre adjacent to each other without gaps
And the propagation path U_YiSimilarly in the gap between each other
And adjacent structures can be adopted. Therefore, the contact position
When specifying the location, make sure that the panel screen can be used without gaps.
Thus, the contact position can be precisely specified. Also,
Propagation path U_XiAre partially overlapping each other
Are two adjacent propagation paths U having the overlapped portion._Xi
Is specified, the contact position is determined by the two propagation paths U
_XiIs determined to be between the two. Propagation path U_YiAre one with each other
The same is true for overlapping parts. Fig. 6 shows piezoelectric electromagnetic
Phase velocity difference under two different electrical boundary conditions of board 1
Electromechanical coupling coefficient k calculated from^TwoAnd the surface acoustic wave
The relationship between the number k and the product (kd) of the thickness d of the non-piezoelectric plate 2 is shown.
FIG. However, in FIG. 6, the non-piezoelectric plate 2 is made of glass.
Of a surface acoustic wave propagating through a single glass plate
Wave speed is 2297m / s and longitudinal wave speed is 4156m /
A characteristic diagram in the case of s is shown. This shear wave speed 229
The values of 7 m / s and longitudinal wave velocity of 4156 m / s are
The shear wave velocity of 2340 m / s in the case of the single electromagnetic plate 1 and
It is almost 0.9 times each of longitudinal wave speed 4390m / s.
You. In FIG. 6, the interdigital electrodes T_XiAnd T_YiAdded to
Electrical energy is particularly significant for surface acoustic waves in the 0th mode.
Are also efficiently converted, and as
It can be seen that there is a tendency to be less likely to occur. IDT
_XiAnd T_YiThe electrical energy applied to the
The kd value is most likely to be converted to surface acoustic wave
1.6, then k^TwoIs about 15.5% of the maximum value
Is shown. Where k^TwoThe value depends on the piezoelectric substrate for surface acoustic waves.
LiNbO in practical use_ThreeThe value of single crystal is about 5%
It is clear that it deserves evaluation even when compared to
You. FIG. 7 is an elasticity table propagating near the surface of the piezoelectric ceramic plate 1.
FIG. 4 is a characteristic diagram showing a phase velocity of a surface wave, and shows a relation between a kd value and each value.
It is a figure showing the phase velocity of a mode. However, in FIG.
In the case where the piezoelectric plate 2 is made of a glass plate of the same material as in FIG.
A gender diagram is shown. Cutoff in higher order modes
There is a frequency. ○ indicates the IDT_XiAnd T
_YiIs applied to the elastic surface of each mode.
Kd value that is most efficiently converted to waves (calculated from FIG. 6)
By value, k^TwoIndicates the maximum value (kd value). 0th mode
The phase velocity (approximately 2170 m / s) at
The pressure when the surface of the porcelain plate 1 is in an electrically short-circuit state
Rayleigh wave velocity (2150 m / s) of the electromagnetic plate 1 alone
Almost equal. Phase of the first and higher order modes in the circle
The speed is almost constant (about 2370 m / s).
Piezoelectric ceramic plate when the surface of the unit is electrically open
One Rayleigh wave velocity (2340m / s)
No. FIG. 8 shows two different electrical boundary conditions of the piezoelectric ceramic plate 1.
K calculated from the phase velocity difference below^TwoValue and kd value
FIG. 7 is a characteristic diagram showing a relationship. However, in FIG. 8, the non-piezoelectric plate 2
An elastic surface that consists of a glass plate and propagates through the glass plate alone
The speed of the shear wave is 1989 m / s and the speed of the longitudinal wave is 359
A characteristic diagram in the case of 8 m / s is shown. This shear wave velocity
Value of 1989 m / s and longitudinal wave velocity of 3598 m / s
Is the transverse wave velocity of 2340 m / s in the case of the piezoelectric ceramic plate 1 alone
0.8 times each of longitudinal wave speed and 4390m / s
It is. In FIG. 8, the interdigital electrodes T_XiAnd T_YiIn addition to
Electric energy is a surface acoustic wave of the 0th mode
Is most efficiently converted to higher order modes.
It can be seen that there is a tendency to be difficult to change. IDT
Extreme T_XiAnd T_Yi0 order electrical energy applied to
The kd value is most easily converted to the mode surface acoustic wave
At about 1.6, then k^TwoIs about 18.5 of the maximum value
%. FIG. 9 shows a bullet propagating near the surface of the piezoelectric ceramic plate 1.
FIG. 4 is a characteristic diagram showing a phase velocity of a surface acoustic wave, with respect to a kd value.
FIG. 4 is a diagram showing a phase velocity in each mode. However, in FIG.
Means that the non-piezoelectric plate 2 is made of a glass plate of the same material as that of FIG.
A characteristic diagram for the case is shown. In the higher order modes,
There is a toe-off frequency. ○ indicates the IDT_XiYou
And T_YiThe electrical energy applied to the
Kd value that is most efficiently converted to a surface acoustic wave (calculated from FIG. 8)
With the value that came out, k^TwoIndicates the maximum value (kd value). 0th order
Phase speed at the mark of mode (about 2095 m / s)
Is the phase velocity of the 0th-order mode shown in FIG.
(About 2170 m / s), but one piezoelectric ceramic plate
Piezoelectric ceramic plate 1 when body surface is in an electrically shorted state
It is almost equal to the Rayleigh wave velocity (2150m / s) of a single substance
No. The phase velocities of the higher-order modes of the first and higher-order modes are almost
With a constant (about 2300 m / s),
The phase velocity of the higher order mode at the circle mark (about 2370 m
/ S), but the surface of the piezoelectric ceramic plate 1 alone is
Rayleigh of the piezoelectric ceramic plate 1 when it is in the open state
It is almost equal to the wave velocity (2340 m / s). Figures 6-9
Therefore, the surface acoustic wave propagated to the non-piezoelectric plate 2 has a zero-order mode and
And higher order mode waves, and the IDT
_XiAnd T_YiThe electrical energy applied to the
The phase velocity that is most easily converted to surface acoustic waves is
Rayleigh propagating to a single piezoelectric ceramic plate 1 in a short-circuit state
-Almost equal to the speed of the waves. In addition, the interdigital electrode T_XiAnd
And T_YiThe electric energy applied to the power is higher than the first order
The phase velocity that is most easily converted to the mode surface acoustic wave is
A laser beam that propagates to the piezoelectric ceramic plate 1 that is electrically open
It is almost equal to the speed of the illy wave. Furthermore, the non-piezoelectric plate 2 alone
Velocity of shear wave and longitudinal wave of surface acoustic wave propagating through
The elasticity table propagated from the piezoelectric ceramic plate 1 to the non-piezoelectric plate 2
The phase velocity of each mode of the surface wave decreases. Similarly,
Interdigital electrode R_XAnd R_YSurface acoustic waves
Especially when converted to a zero-order mode surface acoustic wave
Are efficiently converted to electrical signals and
It can be seen that there is a tendency that conversion is difficult. 0th order
Mode surface acoustic waves are efficiently converted to electrical signals
Is that the phase velocity of the surface acoustic wave in the 0th mode is
Rayleigh propagating to the piezoelectric ceramic plate 1 in a short-circuit state
In this case, the speed is almost equal to the speed of the wave.
Surface acoustic waves are efficiently converted to electrical signals
The phase velocity of the surface acoustic wave of the first or higher order mode is
A laser beam that propagates to the piezoelectric ceramic plate 1 that is electrically open
This is the case where the speed is almost equal to the speed of the illy wave. Also non-piezoelectric
Velocity of shear wave and longitudinal wave of surface acoustic wave propagating in plate 2 alone
Is smaller, the smaller the value of
The phase velocity of each mode of the surface acoustic wave becomes smaller. FIG.
0 indicates a second embodiment of the ultrasonic touch panel of the present invention.
It is sectional drawing. In this embodiment, a piezoelectric ceramic plate 1, a non-piezoelectric plate 2,
Support substrate 3, voltage doubler rectifier 5, comparator 6, information processing
Control unit 7, amplifier AMP and ultrasonic wave transmitting and receiving means X and
Y (the ultrasonic wave transmitting and receiving means X and X in the first embodiment of FIG. 1)
And Y). In this embodiment, the ultrasonic transmission and reception
Wave means X are interdigital electrodes T_XAnd interdigital electrode R
_Xi(I = 1, 2,..., 16)
Means Y are IDTs_YAnd interdigital electrode R_Yi(I
= 1, 2,..., 16). In FIG. 10, a piezoelectric ceramic
Plate 1, non-piezoelectric plate 2, support substrate 3, voltage doubler rectifier 5, capacitor
Parator 6, information processing unit 7, amplifier AMP and ultrasonic wave
Only the transmitting / receiving means X is illustrated. IDT _X,
T_Y, R_XiAnd R_YiConsists of an aluminum thin film. Piezoelectric
Each interdigital electrode is provided on the porcelain plate 1.
The non-piezoelectric plate 2 is provided thereon. Below the piezoelectric ceramic plate 1
Are fixedly supported on the support substrate 3. FIG. 11 shows FIG.
Zero interdigital electrode T_XFIG. IDT
Extreme T_XAnd T_YHave the same structure as each other. Blinds
Electrode R_XiAnd R_YiHave similar structures to each other,
Electrode T_XExcept that the length of the electrode finger is different
It has a similar structure. IDT_XIs 10 pairs of electrodes
Regular type with fingers, electrode period length p is 460 μm
It is. FIG. 12 is a plan view of the ultrasonic touch panel of FIG.
It is. In FIG. 12, the piezoelectric ceramic plate 1 and the interdigital electrodes T
_X, T_Y, R_Xi, R_YiAnd only are drawn. FIG.
FIG. 11 is a diagram showing a driving circuit of the ultrasonic touch panel of FIG.
You. Interdigital electrode R_YiInterdigital electrode R_Y1Is an amplifier
Connected to AMP. IDT_YTelegraph from
No. E_TIs input, the electric signal E_TOut of frequency
Drooping electrode T_YOf the center frequency indicated by
Only the electric signal is converted to a surface acoustic wave, and the piezoelectric ceramic plate 1
Through the vicinity of the surface of the plate surface on which the
And the surface acoustic wave is transmitted to the upper end surface of the non-piezoelectric plate 2.
Carried. Surface acoustic wave propagated to the upper end surface of non-piezoelectric plate 2
Interdigital electrode R_YiThe center frequency shown by
Only the surface acoustic wave of frequency is an electric signal E_Ri(I = 1, 2,
.., 16) and converted into interdigital electrodes R_YiOutput from
It is. This electric signal E_RiIs the voltage doubler rectifier 5 and the
It is sent to the information processing unit 7 via the lator 6. At this time,
Drooping electrode R_YiInterdigital electrode R_Y1Output from
Electric signal E_R1After being amplified by the amplifier AMP,
Bordered electrode T_XAnd T_YIs input to Likewise
And interdigital electrodes T_XFrom the electric signal E_TEntering
Electrical signal E_TIs the elastic surface as in the case of the Y-axis direction
Is converted into a wave and is near the surface of one of the piezoelectric ceramic plates 1
And the surface acoustic wave is transmitted to the upper end face
After being propagated to the_XiFrom the electric signal E_RiWhen
And output. This electric signal E_RiIs a double voltage rectifier 5
It is sent to the information processing section 7 via the comparator 6.
In this way, the IDT T_YAnd R_Y1Elasticity between
Surface wave propagation path U_Y1Oscillator H having a delay element
Have been. At this time, the oscillator H_iThe signal loop of the blinds
Electrode T_Y, Propagation path U_Y1, Interdigital electrode R_Y1And amplification
AMP. Therefore, the circuit configuration can be simplified.
This further promotes the reduction in size and weight of the device, and
Driving at low voltage is possible with low power consumption. Ultrasound of FIG.
The information processing unit 7 in the touch panel has the following functions
You. First, the electric signal E_RiDetecting the size of the
Second, check that the pen tip of the input pen touches the panel screen.
Electric signal E_RiIs reduced or disappears.
Third, attenuated or extinguished electrical signals
E_RiElectrode R corresponding to_XiAnd R_YiIdentify
This specifies the contact position. IDT
Extreme T_XAnd R_XiSurface acoustic wave propagation path U between_Xi(I =
1, 2,..., 16) and the IDT_YAnd R_YiBetween
Surface acoustic wave propagation path U_Yi(I = 2,3, ... ,,
16) When the crossing point is contacted with the pen point, for example,
Propagation path U_X6And U_Y2When contacting the intersection with
Electrode R_X6Signal E output from_R6And interdigital
Pole R_Y2Signal E output from_R2Are each attenuated or
Disappears. Thus, the propagation path U_X6And U_Y2Interaction with
It turns out that the fork is in contact. In addition, FIG.
In the second embodiment, the propagation path U_XiOverlap part of each other,
Propagation path U_YiAlso partially overlap each other. Also
And touching the overlapping part, for example,
Road U_X6And U_X5If touching the overlapped part,
Drooping electrode R_X6And R_X5Electric signal output to each
No. E_R6And E_R5Both attenuate or disappear. Follow
And the propagation path U_X6And U_X5Turned out to be in contact with
I do.

According to the ultrasonic touch panel of the present invention, zero is placed near the surface of the plate surface on which the interdigital transducer of the piezoelectric plate is provided.
It is possible to excite the surface acoustic waves of the second mode and the first-order or higher-order modes and propagate the surface acoustic waves to the upper end surface of the non-piezoelectric plate. At this time, a structure in which the phase velocity of the zero-order mode surface acoustic wave is substantially equal to the velocity of the Rayleigh wave propagating to the piezoelectric plate in an electrically short-circuit state, and a first-order or higher-order surface acoustic wave By adopting a structure in which the phase velocity of the wave is substantially equal to the velocity of the Rayleigh wave propagating through the piezoelectric plate in an electrically open state, the interdigital electrodes T _i and T (hereinafter referred to as the input Not only is it possible to increase the degree to which electric energy applied from the electrodes is converted to surface acoustic waves, but also to reflect, for example, reflections caused by acoustic impedance mismatch at the interface between the piezoelectric and non-piezoelectric plates. Can be removed. Therefore, low power consumption driving becomes possible. Further, it is possible to support a portion of the piezoelectric plate other than the vicinity of the surface of the plate surface on which the interdigital electrodes are provided. In the ultrasonic touch panel of the present invention, the surface acoustic waves of the 0th-order mode and the first-order or higher-order modes propagated to the upper end surface of the non-piezoelectric plate are applied to the plate surface of the piezoelectric plate on which the interdigital electrodes are provided. After propagating near the surface, it can be output as an electrical signal from the interdigital electrodes R and R _i (hereinafter referred to as output interdigital electrodes). At this time, a structure in which the phase velocity of the zero-order mode surface acoustic wave is substantially equal to the velocity of the Rayleigh wave propagating to the piezoelectric plate in an electrically short-circuit state, and a first-order or higher-order surface acoustic wave By adopting a structure in which the phase velocity of the wave is almost equal to the velocity of the Rayleigh wave propagating on the piezoelectric plate in an electrically open state, the surface acoustic wave propagated on the piezoelectric plate is output as an IDT. Can be efficiently output as an electric signal. In addition, it is possible to eliminate reflections or the like caused by acoustic impedance mismatch at the interface between the piezoelectric plate and the non-piezoelectric plate. A structure is adopted in which the thickness of the piezoelectric plate is approximately three times or more the electrode period length p of the interdigital transducer, and the thickness d of the non-piezoelectric plate is smaller than the electrode period length p, and the structure propagates to the non-piezoelectric plate alone. By employing, as the non-piezoelectric plate, a substance in which the phase velocity of the surface acoustic wave is smaller than the phase velocity of the surface acoustic wave propagating to the piezoelectric plate alone, the electric energy applied from the input IDT is reduced to the 0th mode and 1st. It is possible to increase the degree of conversion into a higher-order or higher-order surface acoustic wave. At this time, the surface acoustic wave can be efficiently propagated to the upper end surface of the non-piezoelectric plate without leaking into the inside of the piezoelectric plate. Moreover, the surface acoustic waves of the 0th-order mode and the first-order or higher-order modes propagated to the upper end surface of the non-piezoelectric plate are efficiently converted into electric signals from the output IDT without leaking into the inside of the piezoelectric plate. Can be output.
By adopting piezoelectric ceramics as the piezoelectric plate, it is possible to efficiently excite a surface acoustic wave near the surface of the plate surface on which the IDTs of the piezoelectric plate are provided, and propagate the SAW to the upper end surface of the non-piezoelectric plate. I have to. In addition, the surface acoustic wave propagating on the upper end surface of the non-piezoelectric plate is efficiently propagated to the vicinity of the surface of the plate surface on which each interdigital electrode of the piezoelectric plate is provided, and is output as an electric signal from the output interdigital electrode. It is possible to output. When a piezoelectric ceramic is used as the piezoelectric plate, a structure is adopted in which the direction of the polarization axis of the piezoelectric ceramic is parallel to the thickness direction. When the input and output interdigital electrodes on the panel screen come into contact with the pen tip of the input pen, the propagation path of the surface acoustic wave is cut off, and the electric signal output to the output interdigital electrodes is accordingly reduced. Disappears or decay. Therefore, the contact on the panel screen is sensed in a short response time. Furthermore, the coordinates of the contact position are made to correspond to two-dimensional coordinates with the propagation paths U _Xi and U _Yi as the X axis and the Y axis, respectively, and the contact position is defined as the propagation path U _Xi
And the intersection of U _Yi , the coordinates of the intersection,
That is, the coordinates of the contact position are determined. In addition, the propagation path U _Xi
Adjacent to or partially overlap each other, and employing a structure in which the propagation paths U _Yi are adjacent to or partially overlap with each other, it is possible to more precisely specify the contact position on the panel screen. Become. One output interdigital electrode R and N input interdigital electrodes T
_{In the} ultrasonic touch panel of the type provided with _i, by using N switches Wi connected to each of the N input IDTs, the contact position on the panel screen can be easily determined, and The circuit configuration is simplified. By using the amplifier in a drive circuit, the channel U and _Xi and U _Yi since it is possible to configure the oscillator H _i for a delay element, the circuit structure is simplified, low voltage with low power consumption Can be driven.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of an ultrasonic touch panel according to the present invention.

FIG. 2 is a plan view showing the interdigital transducer T _Xi of FIG. 1;

FIG. 3 is a partial perspective view of the ultrasonic touch panel of FIG. 1;

FIG. 4 is a plan view of the ultrasonic touch panel of FIG. 1;

FIG. 5 is a diagram showing a drive circuit of the ultrasonic touch panel of FIG. 1;

FIG. 6 is a characteristic diagram showing a relationship between a k ² value and a kd value calculated from a phase velocity difference of the piezoelectric ceramic plate 1 under two different electrical boundary conditions.

FIG. 7 is a characteristic diagram showing a phase velocity of a surface acoustic wave propagating near the surface of the piezoelectric ceramic plate 1.

FIG. 8 is a characteristic diagram showing a relationship between a k ² value and a kd value calculated from a phase velocity difference of the piezoelectric ceramic plate 1 under two different electrical boundary conditions.

FIG. 9 is a characteristic diagram showing a phase velocity of a surface acoustic wave propagating near the surface of the piezoelectric ceramic plate 1;

FIG. 10 is a sectional view showing a second embodiment of the ultrasonic touch panel of the present invention.

FIG. 11 is a plan view showing the interdigital electrode T _X of FIG. 10;

FIG. 12 is a plan view of the ultrasonic touch panel of FIG. 10;

FIG. 13 is a diagram showing a driving circuit of the ultrasonic touch panel of FIG. 10;

[Explanation of symbols]

Reference Signs List 1 piezoelectric ceramic plate 2 non-piezoelectric plate 3 support substrate 4 drive unit 5 times voltage rectifier 6 comparator 7 information processing unit T _Xi , T _Yi , R _X , R _Y interdigital transducer W _Xi , W _Yi switch T _X , T _Y , R _Xi , R _Yi IDT AMP Amplifier

Claims (10)

[Claims] An ultrasonic touch panel comprising at least two ultrasonic wave transmitting / receiving means X and Y, a piezoelectric plate, a non-piezoelectric plate, and an information processing unit connected to the ultrasonic wave transmitting / receiving means X and Y. Each of the ultrasonic wave transmitting / receiving means includes N sets of interdigital transducers T _i (i
, N), the interdigital electrodes R and N switches W _i (i = 1, 2,..., N), and the interdigital electrodes T _i and R are provided on one plate surface, the lower end surface of the non-piezoelectric plates have been secured through the respective interdigital transducer in the one plate surface of the piezoelectric plate, the output end of the switch W _i is the interdigital is connected to the input end of the electrode T _i, wherein the interdigital transducer T _i by inputting an electric signal E _T of a frequency substantially corresponding to the interdigital periodicity p of the interdigital transducer T _i, the piezoelectric plate Exciting a surface acoustic wave having a wavelength substantially equal to the electrode period length p near the surface of the one plate surface, and propagating the surface acoustic wave to the upper end surface of the non-piezoelectric plate; The surface acoustic wave propagated to the upper end face is a zero-order mode and a first-order or higher-order mode. The phase velocity of the zero-order mode surface acoustic wave is substantially equal to the velocity of the Rayleigh wave propagating to the piezoelectric plate in an electrically short-circuit state, and the first-order or higher-order surface acoustic wave The phase velocity of the wave is substantially equal to the velocity of the Rayleigh wave propagating to the piezoelectric plate alone in an electrically open state, and the interdigital transducer R transmits the surface acoustic wave propagating to the upper end face of the non-piezoelectric plate. The surface acoustic wave propagated near the surface of the one plate surface of the piezoelectric plate is propagated near the surface of the one plate surface, and the surface acoustic wave propagated near the surface of the one plate surface of the piezoelectric plate substantially corresponds to the electrode period length p of the interdigital transducer R. electrical signal E is converted to _R output of waves of the surface acoustic wave is 0 order mode and first-order or higher-order modes propagating in the vicinity of the surface of the one plate surface of the piezoelectric plate, the wavelength It is almost equal to the electrode cycle length p, The phase velocity of the surface acoustic wave is approximately equal to the velocity of the Rayleigh wave propagating to the piezoelectric plate in an electrically short-circuited state, and the phase velocity of the surface acoustic wave of the first or higher order mode is electric. The velocity of the Rayleigh wave propagating to the piezoelectric plate alone in a substantially open state, the thickness of the piezoelectric plate is approximately three times or more the electrode period length p, and the thickness d of the non-piezoelectric plate is The phase velocity of the surface acoustic wave that is smaller than the electrode period length p and propagates through the non-piezoelectric plate alone is
The smaller than the phase velocity of the surface acoustic wave propagating on the piezoelectric plate alone, the information processing unit is intermittently by sequentially predetermined cycle said switch W _i, detects the magnitude of the electric signal E _R, the non determined by the magnitude of the electrical signal E _R to touch input pen nib of the upper end surface of the piezoelectric plate is attenuated or abolished connection when the magnitude of the electrical signal E _R is attenuated or eliminated ultrasonic touch panel that identifies a contact position by identifying the switch W _i which has been. 2. A propagation path U of a surface acoustic wave between said interdigital transducers T _i and R in said ultrasonic wave transmitting and receiving means X.
_{Xi (i = 1,2, ......,} N) and the propagation path of the surface acoustic wave between the IDT T _i and R in ultrasonic transmitter means Y U _Yi (i = 1,2, .., N) are orthogonal to each other. 3. The ultrasonic touch panel according to claim 2, wherein the propagation paths U _Xi are adjacent to each other or partially overlap each other, and the propagation paths U _Yi are adjacent to each other or partially overlap each other. 4. An oscillator H _i (i = 1, 2,..., N) having the propagation paths U _Xi and U _Yi as delay elements, wherein the switch W in the ultrasonic wave transmitting / receiving means X is provided. The input terminal of _i is connected to the output terminal of the interdigital transducer R in the ultrasonic wave transmitting / receiving means Y via an amplifier _AY. The input terminal of the switch W _i in the ultrasonic wave transmitting / receiving means Y is the are connected via an amplifier a _X to an output terminal of the IDT R in ultrasonic transmitter unit X, the signal loop of the oscillator H _i, the switch W _i in the ultrasonic transmitter means X , The propagation path U _Xi , the amplifier A _X , and the switch W _i in the ultrasonic wave transmitting / receiving means Y, the propagation path U _Yi ,
4. The ultrasonic touch panel according to claim 2, comprising the amplifier _AY . 5. An ultrasonic touch panel comprising at least two ultrasonic wave transmitting / receiving means X and Y, a piezoelectric plate, a non-piezoelectric plate, and an information processing unit connected to said ultrasonic wave transmitting / receiving means X and Y. there, each ultrasonic transmitter unit IDT T and interdigital electrodes _{R i (i = 1,2, ......} , N) consists, said interdigital transducers T and R _i one of said piezoelectric plate The lower end surface of the non-piezoelectric plate is fixed to the one plate surface of the piezoelectric plate via each of the interdigital electrodes, and the interdigital electrode T is formed of the interdigital electrode T. by inputting a substantially corresponding electrical signal E _T frequencies interdigital periodicity p, excites a surface acoustic wave having a wavelength approximately equal to the interdigital periodicity p in the vicinity of the surface of the one plate surface of said piezoelectric plate The surface acoustic wave is applied to the upper end surface of the non-piezoelectric plate. The surface acoustic wave propagated to the upper end surface of the non-piezoelectric plate is a wave of a 0th-order mode and a first-order or higher-order mode, and the phase velocity of the surface acoustic wave of the 0th-order mode is an electric wave. The phase velocity of the surface acoustic wave in the first or higher order mode is almost equal to the velocity of the Rayleigh wave propagating in the piezoelectric plate in a short-circuit state. approximately equal to the Rayleigh wave velocity of the interdigital electrode R _i is allowed to propagate surface acoustic waves propagating on the upper surface of the non-piezoelectric plate in the vicinity of the surface of the one plate surface of the piezoelectric plate, the piezoelectric The surface acoustic wave propagated in the vicinity of the surface of the one plate surface of the plate is converted into an electric signal E _Ri (i = i) having a frequency substantially corresponding to the electrode period length p of the interdigital transducer R _i.
1, 2,..., N), and the surface acoustic waves propagated in the vicinity of the surface of the one plate surface of the piezoelectric plate are waves of a zero-order mode and a first-order or higher-order mode. , The wavelength thereof is substantially equal to the electrode period length p, and the phase velocity of the surface acoustic wave in the zero-order mode is substantially equal to the velocity of the Rayleigh wave propagating to the piezoelectric plate alone in an electrically short-circuit state. The phase velocity of the surface acoustic wave in the higher order mode is almost equal to the velocity of the Rayleigh wave propagating to the piezoelectric plate alone in an electrically open state, and the thickness of the piezoelectric plate is equal to the electrode period length p. The thickness d of the non-piezoelectric plate is smaller than the electrode period length p, and the phase velocity of the surface acoustic wave propagating to the non-piezoelectric plate alone is:
Smaller than the phase velocity of the surface acoustic wave propagating on the piezoelectric plate alone, the information processing unit detects the magnitude of the electric signal E _Ri ,
The contact of the pen tip of the input pen with the upper end surface of the non-piezoelectric plate is determined by the attenuation or disappearance of the electric signal E _Ri , and the attenuated or eliminated electric signal E _Ri is determined.
Ultrasonic touch panel that identifies a contact position by specifying the interdigital electrodes R _i corresponding to _Ri. 6. propagation path U of the surface acoustic wave between the IDT T and R _i in the ultrasonic transmitter means X
_Xi (i = 1, 2,..., N) and a surface acoustic wave propagation path U _Yi (i = 1, 2, 2) between the IDT and R _i in the ultrasonic wave transmitting / receiving means Y. .., N) are orthogonal to each other. 7. The ultrasonic touch panel according to claim 6, wherein the propagation paths U _Xi are adjacent to each other or partially overlap each other, and the propagation paths U _Yi are adjacent to each other or partially overlap each other. 8. An oscillator H having the propagation path U _Y1 of the propagation path U _Yi as a delay element, and an output terminal of the interdigital transducer R ₁ corresponding to the propagation path U _Y1 is connected to the super-high-frequency power supply. The input terminals of the interdigital transducers T in the sound wave transmitting and receiving means X and Y are connected via an amplifier AMP, and the signal loop of the oscillator H includes the interdigital transducer T corresponding to the propagation path U _Y1 , The propagation path U _Y1 , the propagation path U
The interdigital electrode corresponding to _Y1 R ₁ and the amplifier A
The ultrasonic touch panel according to claim 6, comprising an MP. 9. The ultrasonic touch panel according to claim 1, wherein another surface of said piezoelectric plate is supported by a support substrate. 10. The piezoelectric plate is made of a piezoelectric ceramic,
The direction of the polarization axis of the piezoelectric ceramic is parallel to the thickness direction of the piezoelectric ceramic.
10. The ultrasonic touch panel according to 6, 7, 8 or 9.