JP2005092527A - Ultrasonic touch panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively manufacture a panel even if it grows in size, by simplifying its structure, without requiring a reflecting array for reflecting surface acoustic waves. <P>SOLUTION: At the middle of a side on a substrate 10 on which the surface acoustic waves propagate, one transmitting element 12 is installed. On both ends of a side opposite to the one side, receiving elements 14a, 14b are installed. From the transmitting element, ultrasonic vibration is sent, and the surface acoustic waves propagating on the substrate are received by the receiving elements. A direct wave from the transmitting element and a diffracted wave generated by touching are detected by the respective receiving elements, and, from a time difference between a direct wave signal and a diffracted wave signal and a time difference in the diffracted wave signals between the receiving elements, a touch position on the substrate is calculated. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ultrasonic touch panel in which an ultrasonic transmitting element and a receiving element are installed on a substrate on which surface acoustic waves propagate. More specifically, the present invention uses surface acoustic waves that propagate in a plane in an arc shape. Thus, the present invention relates to an ultrasonic touch panel that eliminates the need to form a reflection array that reflects surface acoustic waves around the entire circumference of the substrate and simplifies the structure. This technique can be applied not only to a large touch panel that detects a touch position on a substrate, but also to a small touch panel (switch) that detects only the presence or absence of touch.

  An ultrasonic touch panel installs a transmitting element and a receiving element on a substrate through which surface acoustic waves propagate, transmits ultrasonic vibration from the transmitting element, and receives the surface acoustic waves propagating through the substrate by the receiving element. , An input device that detects the presence or absence of a touch and a touch position.

  As an example of a conventional ultrasonic touch panel, a reflective array that reflects surface acoustic waves is provided on the four sides of a square substrate through which surface acoustic waves propagate, and an X and Y transmitting element is provided at one corner and one of the adjacent adjacent ones. There is a structure in which an X receiving element is provided at a corner and a Y receiving element is provided at the other corner. The reflection array is formed by arranging a large number of parallel protrusions inclined by 45 degrees along the side of the substrate, and functions to change the traveling direction of a part of the surface acoustic wave to a right angle. For example, ultrasonic vibration is emitted from the X transmitting element, and the surface acoustic wave travels along the Y-direction side of the substrate (along one of the Y-direction reflection arrays), and part of it is reflected in the process. The course is changed in the right-angle direction (X direction), and the remaining portion proceeds as it is. As a result, the surface acoustic wave spreads over the entire surface of the substrate. The surface acoustic wave that has crossed the substrate in the X direction is reflected in the perpendicular direction by the opposing reflection array in the Y direction, guided to the X receiving element, and detected. The Y transmitting element and the Y receiving element perform the same operation. Here, when the substrate is touched, the output voltage at the receiving element changes. Therefore, the touch position is detected using various methods using the output voltage.

However, in such an ultrasonic touch panel, it is necessary to provide a reflective array on the entire circumference (four sides) of the substrate. This reflective array is formed by arranging a large number of parallel protrusions inclined at 45 degrees on a glass substrate, and is formed, for example, by screen printing and baking low-melting glass. Therefore, there is a problem that the yield decreases as the substrate size increases, making the manufacturing difficult and the cost high.
Japanese Patent Laid-Open No. 8-179872 JP-A-11-327772

  The problem to be solved by the present invention is that a reflective array requiring fine processing must be provided over the entire circumference of the substrate.

  The present invention relates to an ultrasonic touch panel in which an ultrasonic transmission element and a reception element are installed on a substrate on which surface acoustic waves propagate. The transmission element and the reception element both have a structure in which electrodes are formed on a piezoelectric body. It is installed in the periphery of the transmitter, transmits ultrasonic vibration from the transmitting element, and detects the presence or absence of touch from the presence or absence of vibration attenuation when the surface acoustic wave propagating through the substrate in an arc shape reaches the receiving element. It is an ultrasonic touch panel. In the ultrasonic touch panel in which the ultrasonic transmitting element and the receiving element are installed on a substrate on which surface acoustic waves propagate, the transmitting element and the receiving element have a structure in which electrodes are formed on a piezoelectric body, Detecting the presence or absence of touch by detecting the presence or absence of diffracted waves generated by touching surface acoustic waves that are installed around the substrate and transmit ultrasonic waves from the transmitting element and propagate through the substrate in an arc shape. It is an ultrasonic touch panel characterized by.

  Furthermore, in the present invention, at least one transmitting element and a plurality of receiving elements are installed on a substrate on which surface acoustic waves propagate, the ultrasonic vibration is transmitted from the transmitting elements, and the surface acoustic waves propagating through the substrate are received by the receiving elements. In the ultrasonic touch panel, the transmitting element and the receiving element both have a structure in which electrodes are formed on a piezoelectric body, the transmitting element is spaced on one side of the substrate, and each receiving element is spaced on the opposite side of the substrate. The direct wave of surface acoustic waves propagating through the substrate in an arc shape and the diffracted wave generated by touch are detected by each receiving element, and the direct wave signal and the diffracted wave are transmitted. An ultrasonic touch panel is characterized in that a touch position on a substrate is detected from a time difference between signals and a time difference between diffracted wave signals between receiving elements. Here, one transmitting element and two receiving elements are arranged so that one transmitting element is located at the apex of an isosceles triangle and the receiving elements are located at the other two points, respectively. Arranging on the substrate as described above is also effective in improving detection accuracy.

  In these cases, in the case of a method of detecting a direct wave, the touch intensity can also be detected from the degree of vibration attenuation of the direct wave caused by the touch. The transmitting element and the receiving element have low directivity (propagating surface acoustic waves over a range of approximately 180 degrees). For example, a plurality of concentric arc patterns arranged on one surface of the piezoelectric body and each arc pattern An arc-shaped electrode having a connection pattern for connecting the electrodes is provided and a full-surface electrode is provided on the other surface, and the arc-shaped electrode is attached so as to be in contact with the substrate.

  In the present invention, the term “touch panel” is used as a term of a broad concept including not only a large touch panel that detects a touch position on a substrate but also a small touch panel (touch switch) that simply detects the presence or absence of touch. ing.

  In the ultrasonic touch panel according to the present invention, it is not necessary to provide a reflective array of surface acoustic waves that requires fine processing over the entire circumference of the substrate, and therefore the yield does not decrease even if the substrate is enlarged. Since the present invention has a simple structure in which the transmitting element and the receiving element are simply pasted on the substrate, the manufacturing cost does not increase even when the size is increased.

  One transmitting element is installed at the center of one side of the substrate on which surface acoustic waves propagate, and receiving elements are installed at both ends of the opposite side to transmit ultrasonic vibration from the transmitting element and receive surface acoustic waves propagating through the substrate. The device is configured to receive. Both the transmitting element and the receiving element have a structure in which an arc-shaped electrode is formed on a piezoelectric body. Then, an ultrasonic vibration is transmitted from the transmitting element so that the surface acoustic wave propagates in an arc shape (planar) through the substrate, and the direct wave and the diffracted wave generated by the touch are detected by each receiving element. The touch position on the substrate is calculated from the time difference between the signal and the diffracted wave signal and the time difference between the diffracted wave signals between the receiving elements.

  An embodiment of an ultrasonic touch panel according to the present invention is shown in FIG. This is a small device designed to function as a touch switch. An ultrasonic transmitting element 12 is installed at the center of one side of the substrate 10 on which the surface acoustic wave propagates, and an ultrasonic receiving element 14 is installed at the center of the opposite side. The substrate 10 is made of, for example, a glass plate. Both the transmitting element 12 and the receiving element 14 have a structure having an arc-shaped electrode on the surface of a thin plate-like piezoelectric body, ultrasonic vibrations are transmitted from the transmitting element 12, and surface acoustic waves propagate through the substrate 10 in an arc shape. Thus, the receiving element 14 is configured to receive the surface acoustic wave that arrives and convert it to an output voltage.

  The transmitting element 12 and the receiving element 14 may have the same structure. An example is shown in FIG. A shows a longitudinal section, and B shows an arcuate electrode. The transmitting element 12 (or the receiving element 14) includes a plurality of concentric arc-shaped patterns 22 arranged on one surface (bottom surface) of the thin plate-like piezoelectric body 20, and connection patterns 23 that connect the arc-shaped patterns 22 to each other. The arc-shaped electrode 24 is provided, and the entire surface electrode 26 is provided on the other surface (upper surface). The arc pattern is illustrated here as a semi-elliptical shape, but may be a semi-circular shape. The transmitting element 12 (or the receiving element 14) is attached with an adhesive so that the protruding direction of the arc-shaped electrode 24 faces the center of the substrate 10 and the arc-shaped electrode 24 is in contact with the substrate 10. The adhesive layer is preferably made as thin as possible in consideration of absorbing vibration. The plurality of arc-shaped patterns 22 are arranged concentrically in order to improve the excitation power. The distance between the arc-shaped patterns 22 is, for example, about 400 μm, and is adjusted so as to be excited at a frequency of 5 MHz. Note that it is desirable that the arc-shaped electrode 24 generate single-frequency vibration (sine wave vibration).

  In the transmitting element 12, by applying a predetermined voltage between the entire surface electrode 26 on the upper surface and the arc-shaped electrode 24 on the bottom surface, element vibration based on the piezoelectric action occurs, and surface acoustic waves having a wavelength corresponding to the interval between the arc-shaped patterns. Is excited, and the vibration propagates in a circular arc shape on the substrate 10. Here, the burst wave drive is performed so as to repeat a cycle in which vibration of a single frequency of 5 MHz continues for a certain period of time during which the voltage is applied, and then the vibration is interrupted for a certain period of time by stopping the voltage application. When the vibration propagated through the substrate 10 reaches the receiving element 14, the intensity of the vibration is converted into a voltage by the piezoelectric action and detected.

  In the configuration of FIG. 1, when the substrate 10 is not touched with a finger, the ultrasonic vibration emitted from the transmitting element 12 directly reaches the receiving element 14, and thus a large voltage is detected. However, when the substrate 10 is touched with a finger (the touch location is indicated by reference numeral “16”), the surface acoustic wave propagating through the substrate 10 is hindered, making it difficult to reach the receiving element 14 and decreasing the output voltage. That is, since the presence or absence of vibration attenuation of the direct wave can be detected by a change in the output voltage, it is possible to detect the presence or absence of touch. Further, since the degree of vibration attenuation of the direct wave varies depending on the strength with which the finger touches the substrate 10, the touch intensity can be detected by the output voltage of the direct wave received by the receiving element 14.

  FIG. 3 shows another embodiment of the ultrasonic touch panel according to the present invention. This is also a small device designed to function as a touch switch. An ultrasonic transmission element 12 is installed at one corner on the substrate 10 where the surface acoustic wave propagates, and an ultrasonic reception element 14 is installed at one corner adjacent to the ultrasonic transmission element 12. Other configurations except the installation position may be the same as those in FIG. An ultrasonic burst wave is transmitted from the transmitting element 12, and the surface acoustic wave propagates in a circular arc shape on the substrate 10. When the substrate 10 is not touched with a finger, the ultrasonic vibration emitted from the transmitting element 12 is difficult to reach the receiving element 14 directly, so only a small voltage is detected. However, when the substrate 10 is touched with a finger (the touch location is indicated by reference numeral “16”), the surface acoustic wave propagating through the substrate 10 causes a diffraction phenomenon by the touched finger edge, and the diffracted wave (indicated by a dotted line) is generated. It propagates on the substrate 10 and reaches the receiving element 14. That is, an output voltage is generated due to diffracted wave vibration. Therefore, the presence or absence of the touch can be detected by detecting the diffracted wave generated by the touch of the finger with the receiving element 14.

  An example of the output voltage waveform is shown in FIG. A dotted line is a case where the substrate is not touched, and a voltage due to only a direct wave appears. When the substrate 10 is touched with a finger, a voltage due to a diffracted wave appears in addition to the direct wave, as shown by a solid line. Therefore, if the output voltage is detected at the timing when the diffracted wave appears, the presence or absence of touch can be detected.

  FIG. 5 shows still another embodiment of the ultrasonic touch panel according to the present invention. This is a large device having a function of detecting a touch position. One transmitting element 12 is installed at the center of one side on the substrate 10 on which the surface acoustic wave propagates, and receiving elements 14a and 14b are installed at both ends of the opposite side. Each of the transmitting element 12 and the receiving elements 14a and 14b has a structure in which an arc-like electrode is formed on a thin plate-like piezoelectric body, as shown in FIG. And it is comprised so that the receiving element 14a, 14b may receive the surface acoustic wave which transmits ultrasonic vibration from the transmission element 12, and propagates the board | substrate 10 in circular arc shape (plane shape). When the substrate 10 is touched with a finger, the surface acoustic wave is diffracted by the edge of the touched finger, and the diffracted wave also reaches the receiving elements 14a and 14b.

  Both receiving elements 14a and 14b detect a direct wave from the transmitting element 12 and a diffracted wave generated by touch. An example of the output voltage waveform is shown in FIG. The touch position on the substrate 10 can be calculated from the time difference between the direct wave signal and the diffracted wave signal at one receiving element (for example, 14a) and the time difference between the diffracted wave signals between the receiving elements 14a and 14b. Further, the touch intensity can be detected by comparing the signal intensity of the direct wave at the time of no touch and the signal intensity of the direct wave at the time of touch. In FIG. 6, the alternate long and short dash line is a case where the substrate is not touched, and only a direct wave appears. When touching the substrate, a diffracted wave appears in addition to the direct wave. The solid line indicates the output voltage detected by one receiving element 14a, and the dotted line indicates the output voltage detected by the other receiving element 14b. Therefore, the touch position can be obtained by measuring the timing at which the output signal due to the diffracted wave appears (peak position of the output voltage).

For example, as shown in FIG. 5, when the arrangement relationship is such that one transmitting element 12 and two receiving elements 14a and 14b are positioned at the vertices of an isosceles triangle, the coordinates of the transmitting element 12 are [0, 0]. The coordinates of one receiving element 14a are [1, 1], and the coordinates of the other receiving element 14b are [1, -1]. Further, the touch position is [x, y]. In FIG. 6, assuming that the time difference between the direct wave and the diffracted wave appearing on one receiving element 14a is T1, and the time difference between the diffracted waves appearing on one receiving element 14a and the other receiving element 14b is T2, vibrations propagate through them. Since it is proportional to the distance,
T1∝ (B1 + B2) -A
T2∝B3-B2
It can be expressed as here,
A = √2
B1 = √ (x ² + y ² )
B2 = √ ((1-x) ² + (1-y) ² )
B3 = √ ((1-x) ² + (1 + y) ² )
A: Distance from transmitting element 12 to one receiving element 14a B1: Distance from transmitting element 12 to touch position 16 B2: Distance from touch position 16 to one receiving element 14a B3: Distance from touch position 16 to other receiving element The distance to 14b. Accordingly, the time differences T1 and T2 are functions of the touch positions x and y, and the touch position [x, y] can be calculated by measuring T1 and T2. Furthermore, the touch strength can be detected based on the amplitude of the direct wave without touch and the degree of vibration attenuation of the amplitude when touched.

  FIG. 7 shows still another embodiment of the ultrasonic touch panel according to the present invention. Basically, like FIG. 5, one transmitting element 12 is installed at the center of one side on the substrate 10 on which surface acoustic waves propagate, and receiving elements 14a and 14b are installed at both ends of the opposite side. The configuration is such that the surface acoustic wave that transmits the sonic vibration and propagates through the substrate 10 is received by the receiving elements 14a and 14b. The arrangement is such that one transmitting element 12 is positioned at the apex of an isosceles triangle and the receiving elements 14a and 14b are positioned at the other two points, and this is a set. A set of one transmitting element 32 and two receiving elements 34a and 34b having the same arrangement relationship is placed on the substrate 10 symmetrically with the set. FIG. 7 shows a direct wave and a diffracted wave when a set of the transmitting element 12 and the receiving elements 14a and 14b is used.

  As described above, when the number of transmitting elements and receiving elements is increased, the detection accuracy can be improved. This is because an area with low detection accuracy on the substrate can be eliminated. The measurement may be performed by, for example, one transmitting element and receiving element pair, and then repeating the operation of shifting the timing and performing another transmitting element and receiving element pair.

  As mentioned above, although the preferable Example of this invention was explained in full detail, this invention is not limited only to this structure. The installation position of the transmitting element and the receiving element, the electrode structure, and the like can be appropriately changed according to the use conditions. One of the electrodes may have an arc shape, an arc shape using a part of an elliptical circumference, a part of various curves such as a parabola, or a matrix shape divided into fine pieces. The transmitting element and the receiving element are not necessarily the same.

Explanatory drawing which shows one Example of the ultrasonic type touch panel which concerns on this invention. Explanatory drawing of a transmitting element (or receiving element). Explanatory drawing which shows the other Example of the ultrasonic type touch panel which concerns on this invention. Explanatory drawing of the output voltage waveform detected with the receiving element. Explanatory drawing which shows the further another Example of the ultrasonic type touch panel which concerns on this invention. Explanatory drawing of the output voltage waveform detected with the both receiving elements. Explanatory drawing which shows the further another Example of the ultrasonic type touch panel which concerns on this invention.

Explanation of symbols

10 Substrate 12 Transmitting element 14, 14a, 14b Receiving element 16 Touch position

Claims (6)

In an ultrasonic touch panel in which ultrasonic transmitting elements and receiving elements are installed on a substrate on which surface acoustic waves propagate,
Both the transmitting element and the receiving element have a structure in which electrodes are formed on a piezoelectric body. The transmitting element and the receiving element are installed in the periphery of the substrate, transmit ultrasonic vibration from the transmitting element, and surface acoustic waves propagating in an arc shape through the substrate receive element. An ultrasonic touch panel characterized by detecting the presence or absence of a touch from the presence or absence of vibration attenuation when reaching the point. In an ultrasonic touch panel in which ultrasonic transmitting elements and receiving elements are installed on a substrate on which surface acoustic waves propagate,
Both the transmitting element and the receiving element have a structure in which an electrode is formed on a piezoelectric body. The transmitting element and the receiving element are installed on the periphery of the substrate, transmit ultrasonic vibration from the transmitting element, and touch the surface acoustic wave that propagates in an arc shape in the substrate. An ultrasonic touch panel, wherein presence or absence of a touch is detected by detecting presence or absence of a diffracted wave generated by a receiving element. An ultrasonic device in which at least one transmitting element and a plurality of receiving elements are installed on a substrate on which surface acoustic waves propagate, and ultrasonic vibrations are transmitted from the transmitting elements, and the surface acoustic waves propagating through the substrate are received by the receiving elements. In sonic touch panel,
Both the transmitting element and the receiving element have a structure in which an electrode is formed on a piezoelectric body. The transmitting element is disposed on one side of the substrate, and each receiving element is disposed at an interval on the opposite side of the substrate. Each receiving element detects a direct surface acoustic wave wave that propagates vibration and propagates in a circular arc shape on the substrate, and a diffracted wave generated by touch, and the time difference between the direct wave signal and the diffracted wave signal and the diffracted wave between the receiving elements. An ultrasonic touch panel, wherein a touch position on a substrate is calculated from a time difference between signals. One transmitting element and two receiving elements are arranged so that one transmitting element is located at the apex of an isosceles triangle and the receiving element is located at each of the other two points. The ultrasonic touch panel according to claim 3, which is disposed on the surface. The ultrasonic touch panel according to claim 1, wherein the touch intensity is also detected from a degree of vibration attenuation of the direct wave generated by the touch. Each of the transmitting element and the receiving element is provided with an arc-shaped electrode having a plurality of concentrically arranged arc-shaped patterns on one surface of the thin plate-shaped piezoelectric member and a connection pattern for connecting the arc-shaped patterns, and an entire surface electrode on the other surface. The ultrasonic touch panel according to claim 1, wherein the arc-shaped electrode is attached so as to be in contact with the substrate.

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