JP2005100475A - Touch panel device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a touch panel device capable of detecting a touch position of an object and of detecting an instructed direction, even if the object does not move, with a small-sized and simple structure. <P>SOLUTION: Surface acoustic waves are transmitted from each of a plurality of exciting elements provided to one end part of a non-piezoelectric substrate, the surface acoustic waves for propagating a non-piezoelectric substrate by each of the plurality of receiving elements which are provided in opposition to the respective exciting elements at the other end part are received and, based on reception results by the receiving elements, a position of an object in touch with the non-piezoelectric substrate is detected. Also, on the basis of the reception level of the surface acoustic waves in the receiving elements, an instructed direction is detected. With a center location C of a scope S (contact scope) whose reception level is equal to or lower than a specified level as a starting point, a direction of a vector (vector CG) having a center of gravity location G calculated based on the reception level as a terminal point is detected as a direction which a user has instructed. Even when the object stays at one place, the instructed direction can be detected. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a touch panel device that detects contact of an object such as a finger or an indicator, and more particularly to a touch panel device that detects contact of an object by detecting surface acoustic wave blocking using an IDT.

  With the widespread use of computer systems such as personal computers, new information can be input by pointing on the display screen of a display device on which information is displayed by a computer system with an object such as a finger or an indicator. Devices that give various instructions to the system are used. When an input operation is performed on the information displayed on the display screen of a display device such as a personal computer by a touch method, it is necessary to detect the contact position (indicated position) on the display screen with high accuracy. .

As a touch panel device that detects a contact position of an object, a device using a resistance film and a device using an ultrasonic wave are well known. In the former apparatus using a resistance film, a change in the resistance value of the resistance film caused by an object coming into contact with the resistance film is detected. This requires less power consumption but has problems in response time, detection performance, and durability. In the latter apparatus using ultrasonic waves, a surface acoustic wave (SAW) is propagated to a non-piezoelectric substrate, and attenuation of the surface acoustic wave caused by an object coming into contact with the non-piezoelectric substrate is detected. A touch panel device using an element formed of an IDT (Inter Digital Transducer) and a piezoelectric thin film as an excitation element for exciting the surface acoustic wave and a receiving element for receiving the propagated surface acoustic wave is proposed. Has been.
JP-A-6-43995

  In this touch panel device, a plurality of excitation elements composed of an IDT and a piezoelectric thin film are provided at one end portion of a non-piezoelectric substrate, and the other end portion of the non-piezoelectric substrate is composed of an IDT and a piezoelectric thin film. A plurality of receiving elements are provided. An electric signal is input to each excitation element to excite the surface acoustic wave, propagate through the non-piezoelectric substrate, and the propagated surface acoustic wave is received by the receiving element. When an object comes into contact with the propagation path of the surface acoustic wave on the non-piezoelectric substrate, the surface acoustic wave is attenuated. Therefore, it is possible to detect the presence or absence of contact by detecting the presence or absence of level attenuation of the received signal of the receiving element.

  In the conventional touch panel device, the center frequency of each IDT in all excitation elements and reception elements is the same, and the IDT connected to the excitation / reception circuit is switched to detect which reception element the received signal has attenuated. By doing so, it is detected that an object is in contact with the propagation path between the receiving element and the excitation element facing the receiving element. In order to increase the detection accuracy, it is conceivable to reduce the arrangement interval of these excitation elements and reception elements. However, when the arrangement pitch is narrowed in this way, there is a high possibility that a surface acoustic wave from a certain excitation element is received by an adjacent receiving element that does not face the surface acoustic wave. At this time, since the center frequency is the same in any pair of opposing excitation elements / receiving elements in the conventional touch panel device, the surface acoustic wave from the adjacent excitation element is received as it is, and the normal excitation element from the opposing excitation element is received. Indistinguishable from surface acoustic waves. Therefore, there is a problem that a detection error is caused.

  The present invention has been made in view of such circumstances, and even if an object such as a finger or an indicator stays in one place, the direction instruction by the user is given based on the reception level of the surface acoustic wave in the receiving element. An object of the present invention is to provide a touch panel device that can be detected.

  A touch panel device according to the present invention is provided on a substrate, a plurality of excitation elements that are provided on the substrate, respectively, and each of the plurality of excitation elements is opposed to the substrate. A plurality of receiving elements that respectively receive surface acoustic waves, the surface acoustic waves propagate to the substrate between the exciting element and the receiving element facing each other, and the surface acoustic waves are received by the receiving element It is characterized in that the direction of a vector connecting the center position of the range where the level is equal to or lower than the predetermined level and the position obtained based on the reception level of the surface acoustic wave at the receiving element is detected.

  The IDT itself has bandpass filter characteristics, and receives and receives a surface acoustic wave having only a passband frequency defined by a predetermined center frequency and a predetermined bandwidth with respect to an input frequency. In the present invention, a plurality of excitation elements composed of IDTs and piezoelectric films are arranged at one end of the substrate, and a plurality of reception elements composed of IDTs and piezoelectric films are arranged on the substrate so as to face each of these excitation elements. Arranged at the other end. Then, a surface acoustic wave is transmitted from each of the plurality of excitation elements to the non-piezoelectric substrate, a surface acoustic wave is received from each excitation element opposed to each of the plurality of reception elements, and based on the reception result at the reception element, The position of the object in contact with the substrate is detected.

  In the present invention, the instructed direction is detected based on the reception level of the surface acoustic wave at the receiving element. A touch panel device using surface acoustic waves has a feature that the amount of attenuation varies depending on the force pressed by an object. Therefore, the direction of a vector whose starting point is the center position of the range (contact range) where the reception level is equal to or lower than the predetermined level and whose end point is the position obtained based on the reception level is detected as the direction designated by the user. Therefore, even when the object is not moving, that is, when the object stays in one place, the instructed direction can be detected.

  The touch panel device of the present invention can detect the direction instructed by the user without the user moving an object such as a finger or an indicator. Therefore, for example, when the user instructs the moving direction of the cursor, the same function as that of the stick-type pointing device can be easily achieved without moving the contact position.

Hereinafter, the present invention will be described in detail with reference to the drawings showing embodiments thereof.
(First embodiment)
FIG. 1 is a schematic diagram illustrating a basic configuration of a touch panel device. In the figure, reference numeral 1 denotes a rectangular non-piezoelectric substrate made of, for example, a glass substrate. A plurality of (specifically seven) excitation elements 2 that excite surface acoustic waves are arranged and formed at one end of the substrate 1. A plurality of (specifically seven) receiving elements 3 for receiving surface acoustic waves are formed in an array on the other end of the substrate 1 so as to face the respective excitation elements 2.

  Each excitation element 2 and each receiving element 3 have the same shape, and are formed by laminating an IDT and a piezoelectric thin film and performing a process as described later. The IDT has two interdigitated metal patterns made of aluminum, for example, and exchanges microwave voltages with surface acoustic waves. The IDT itself has bandpass filter characteristics. Therefore, each excitation element 2 excites a surface acoustic wave having only a pass band frequency defined by a predetermined center frequency and a predetermined bandwidth with respect to the input frequency. On the other hand, each receiving element 3 receives a surface acoustic wave having only a passband frequency defined similarly.

The IDT of the pair of exciting elements 2 facing each other and the IDT of the receiving element 3 have the same center frequency, and the exciting elements 2 and 2 and the receiving elements 3 and 3 constituting the adjacent pair are center frequencies of the IDT. Is different. The center frequencies are sequentially set to f ₁ , f ₂ , f ₃ , f ₄ , f ₅ , f ₆ , and f ₇ from the pair on the right side of FIG. The frequency f ₁ is the lowest and increases sequentially with f ₂ , f ₃ , f ₄ , f ₅ , and f ₆ , and the frequency f ₇ is the highest. However, the difference between the center frequencies of adjacent pairs is made larger than the bandwidth of each pair.

  The surface acoustic wave excited by the IDT of each excitation element 2 has substantially the same width as the opening of the IDT, travels substantially straight, propagates through the substrate 1, and is received by each opposing receiving element 3. A region sandwiched between the excitation element 2 and the reception element 3 is a detection range 1a for detecting the contact of the finger A. Each excitation element 2 is connected to a common electrode 4 for excitation, and each reception element 3 is connected to a common electrode 5 for reception. These common electrode 4 and common electrode 5 are connected to a detection circuit 10. The detection circuit 10 includes an MPU 11, a D / A converter 12, a VCO (Voltage Controlled Oscillator) 13, a counter 14, a peak hold circuit 15, and an A / D converter 16.

  The MPU 11 instructs a desired output voltage to the D / A converter 12. The instruction voltage is converted into an analog signal by the D / A converter 12 and input to the VCO 13. The VCO 13 oscillates at a frequency that is uniquely determined by the input voltage. The number of oscillations of the VCO 13 is counted by the counter 14, and the MPU 11 measures the output frequency of the VCO 13 from the count value of the counter 14. The system of the VCO 13, the counter 14 and the MPU 11 functions as a feedback system for enabling the VCO 13 to oscillate at a desired accurate frequency. The VCO 13 is connected to the common electrode 4 for excitation, and the oscillation frequency is applied to the common electrode 4. The oscillation frequency in the VCO 13 is changed every predetermined period, and each corresponding excitation element 2 excites at its center frequency and a predetermined bandwidth according to each frequency.

  A peak hold circuit 15 is connected to the common electrode 5 for reception. The peak hold circuit 15 holds the peak voltage of the received waveform at each receiving element 3. The A / D converter 16 converts the output voltage of the peak hold circuit 15 into a digital value and outputs the digital value to the MPU 11. The MPU 11 detects the contact position of the finger A based on this output.

  Note that the above configuration shows the basic configuration of the detection circuit 10 in the touch panel device. Furthermore, a circuit for matching IMP may be provided between the VCO 13 and the common electrode 4 for excitation. In addition, a circuit for amplifying the received signal or converting it to another format may be provided on the receiving side so that the detected received signal can be used effectively. For example, a circuit may be provided that performs logarithmic conversion of the received signal and performs linear inverse conversion from a certain reference value.

  Here, a manufacturing method of the excitation element 2 and the reception element 3 on the substrate 1 will be described with reference to FIG. An aluminum electrode film 21 is formed on the glass substrate 1 by vapor deposition or sputtering (FIG. 2A). Next, after forming a mask pattern for forming an IDT with the photoresist 22 (FIG. 2B), an IDT 23 which is an aluminum electrode film pattern is formed by etching (FIG. 2C). A metal mask 24 having an opening is attached to the IDT 23 forming portion (FIG. 2D). After forming the ZnO thin film 25 to be a piezoelectric thin film by sputtering, the metal mask 24 is removed, and the excitation element 2 and the receiving element 3 composed of the IDT 23 and the ZnO thin film 25 are produced (FIG. 2 (e)). .

Next, the contact position detection operation by the touch panel device having such a configuration will be described. FIG. 3 is a diagram illustrating a time series of the excitation signal in the excitation element 2 and the reception signal in the reception element 3. Voltage data is output from the MPU 11 to the D / A converter 12. This voltage data is converted to an analog signal by the D / A converter 12 and output to the VCO 13, and f ₁ , f ₂ , f ₃ , f ₄ , f ₅ , f ₆ , A sine wave whose frequency changes periodically with f ₇ is input. Further, the relationship between the voltage applied to the VCO 13 and the oscillation frequency is measured by using the feedback system of the VCO 13, the counter 14 and the MPU 11 at regular intervals, and the voltage applied to the VCO 13 is adjusted.

When the frequency of the input signal is f ₁ , the surface acoustic wave propagates through the substrate 1 between the excitation element 2 / reception element 3 whose center frequency is f ₁ , and the excitation element 2 / reception element having other center frequencies. The pair of 3 is out of band and the surface acoustic wave does not propagate. Similarly, when the frequency of the input signal is f _n (n = 2, 3, 4, 5, 6, 7), a surface acoustic wave is generated between the excitation element 2 and the reception element 3 whose center frequency is f _n. The excitation element 2 / reception element 3 pair that propagates through the substrate 1 and has a center frequency other than that is out of band and does not propagate surface acoustic waves. The propagated surface acoustic waves having the center frequencies are received by the corresponding receiving elements 3. The received signal is sent to the peak hold circuit 15 through the common electrode 5 for reception, where a peak is obtained, and a digital peak value is output from the A / D converter 16 to the MPU 11.

Here, when the substrate 1 is not touched with a finger or the like, the amplitude levels of the reception signals of the surface acoustic waves of the respective center frequencies are the same. On the other hand, as shown in FIG. 1, when the finger A is in contact with the substrate 1, the surface acoustic wave whose contact range corresponds to the propagation path is blocked by the finger A, and the amplitude level of the received signal is Attenuates. In the example of FIG. 1, the contact range of the finger A depends on the propagation path of the surface acoustic wave having the center frequencies f ₄ and f _5, and the contact position is closer to the latter propagation path. The propagation amount of the surface acoustic wave is the smallest in the propagation path of the center frequency f ₅ closest to the contact position of the finger A, and then the propagation amount of the center frequency f ₄ is small. As a result, the received signal output to the common electrode 5 also has the lowest amplitude level in the receiving element 3 having the center frequency f ₅ and then lowers in the receiving element 3 having the center frequency f ₄ .

Therefore, based on the peak value of the received signal at each center frequency, the contact position can be detected from the propagation path in which the peak value decreases. In the example of FIG. 1, the propagation path having the center frequency f ₅ can be set as the contact position. In order to detect the contact position in more detail, the attenuation level of the amplitude level of the received signal may be compared. In the example of FIG. 1, the contact position is obtained from the ratio of the attenuation amount of the received signal between the center frequencies f ₄ and f ₅ . Specifically, the contact position X is calculated by the following equation (1).
X = L × V ₁₄ / (V ₁₄ + V ₁₅ ) (1)
X: center distance from the center of the propagation path of the frequency f ₅ the propagation path direction of the center frequency f ₄ L: center frequency f _4, f ₅ the propagation path of the center distance V _14: attenuation of the center frequency f ₄ V _15: attenuation of the center frequency f ₅

Further, when the substrate 1 is brought into contact with a large object, the plurality of propagation paths are completely blocked. Therefore, the width of the object in contact can be obtained from the number of received signals that are attenuated. Specifically, the width W of the object is calculated by the following equation (2).
W = k × L (2)
k: Number of received signals that are attenuated L: Distance between centers of adjacent propagation paths when the propagation paths are equally spaced

  FIG. 4 is a flowchart showing an operation procedure in the MPU 11. Voltage data is output from the MPU 11 to the D / A converter 12 (step S1). Then, the output data of the A / D converter 16 at the center frequency corresponding to the voltage data is input to the MPU 11 (step S2). The above processing is performed for all pairs of the excitation element 2 / reception element 3, and when it is completed (step S3: YES), it is determined whether there is an attenuation in the received signal. (Step S4). If it exists (S4: YES), the contact position is calculated (step S5). On the other hand, if it does not exist (S4: NO), the operation is terminated without performing the contact position calculation process.

  As described above, since the center frequencies of the adjacent excitation element 2 / reception element 3 pairs are different from each other, the surface acoustic wave from the adjacent excitation element 2 that is not opposed is not received by the reception element 3. Only the surface acoustic wave from the opposing excitation element 2 is received by the receiving element 3. Therefore, the contact position of the object can be easily detected by detecting the level attenuation of the reception signal at each center frequency. Further, even when a plurality of pairs of the excitation element 2 / receiving element 3 are arranged at a narrow pitch, the adjacent pair is not affected, so that the detection performance is not deteriorated and a highly accurate detection result can be obtained. .

(Second Embodiment)
FIG. 5 is a timing chart showing excitation / reception processing in the touch panel device according to the first embodiment. In this example, after the excitation process and the reception process at the center frequency f _n are completed, the excitation process at the next center frequency f _{n + 1} is started. Since the surface acoustic wave is a sound wave, the propagation speed is extremely slow compared to an electrical signal, and processing delay becomes a problem. In FIG. 5, D represents a delay time due to propagation from the excitation element 2 to the reception element 3. Accordingly, since it takes a long time to complete the excitation process and the reception process for all pairs, the contact position cannot be detected quickly.

FIG. 6 is a timing chart showing excitation / reception processing in the touch panel device according to the second embodiment, and FIG. 7 is a schematic diagram showing the propagation state of the surface acoustic wave. In this example, without waiting for completion of the excitation process at the center frequency f _n, start excitation process at the next center frequency f _{n + 1.} By doing in this way, the delay which is a difficulty at the time of using a surface acoustic wave can be eliminated, and a contact position can be detected rapidly.

(Third embodiment)
In the second embodiment, the excitation process in the excitation element 2 is continued until reception by the reception element 3 is started with respect to the pair of excitation elements 2 / reception elements 3. However, it is not necessary to excite the excitation element 2 over such a long period of time, and it is sufficient to excite it for a time sufficient for the reception process in the reception element 3.

FIG. 8 is a timing chart showing excitation / reception processing in the touch panel device according to the third embodiment, and FIGS. 9A and 9B are schematic views showing the propagation states of the surface acoustic waves. In this example, the excitation time at each excitation element 2 for the center frequencies f ₁ , f ₂ ,..., F _N is set to a time sufficient for the reception process at the reception element 3. Specifically, each excitation time is set to about (IDT length of the receiving element 3 / surface acoustic wave velocity on the substrate 1). In addition, the excitation stop time in the intermittent burst change is set to be equal to or less than (distance between the IDT of the excitation element 2 and the IDT of the receiving element 3 / surface acoustic wave velocity on the substrate 1). The intensity of the surface acoustic wave generated by the burst-like excitation signal becomes maximum at the passing time of the IDT length of the receiving element 3, and the intensity becomes constant at the excitation time longer than that. Therefore, the excitation is stopped when the maximum value is reached.

  Accordingly, detection delay can be eliminated as in the second embodiment, excitation / reception processing can be performed efficiently, and a great effect is achieved in reducing power consumption. 9A and 9B show such an example, and FIG. 9B shows an example of the shortest time when the excitation stop period = 0. Further, the receiving process is not performed in each receiving element 3 by the blocking process for the delay time in the initial stage of excitation (D in FIG. 8). Therefore, erroneous detection due to the influence of noise can be prevented. This delay time can be determined by (the distance between the IDT of the excitation element 2 and the IDT of the receiving element 3 / the speed of the surface acoustic wave on the substrate 1) in designing the touch panel device. In addition, as the blocking process at this time, physical blocking by the gate IC, addition of prohibition of reception processing by firmware, or the like can be used.

FIG. 10 is a flowchart showing an operation procedure in the MPU 11 in the second and third embodiments. In the touch panel device configured by IDT pairs of center frequencies f ₁ ,..., F _N and sequentially exciting / receiving surface acoustic waves of each center frequency, V _(ni) is voltage data for exciting frequency f _ni , v _(no) represents the received voltage data at the frequency f _no . M represents the number of frequencies transmitted during the gate cutoff time D in FIG. This flowchart includes a loop (loop 1) that performs only the excitation operation and does not perform the reception operation, a loop (loop 2) that performs the excitation operation and the reception operation simultaneously, and a loop (only the reception operation that does not perform the excitation operation). Loop 3).

In order to initialize, an initial value 1 is given to ni and no (step S11). Voltage data V _(ni) for frequency f _ni excitation is output from the MPU 11 to the D / A converter 12 (step S12). ni is incremented by 1, and a number corresponding to the next frequency is set (step S13). ni whether reaches m + 1, to determine that is it has excitation frequency f _m (step S14). If not reached (S14: YES), the process returns to S12 by loop 1. When it has been reached (S14: NO), the voltage data v _(no) received at the frequency f _no in the A / D converter 16 is input to the MPU 11, and the voltage data v _(no) and a preset judgment level are input. The data h _(no) is compared to detect the presence or absence of blocking of the surface acoustic wave (step S15). No is incremented by 1 and a number corresponding to the next frequency is set (step S16). It is determined whether ni has reached N + 1, that is, whether the frequency f _N has been excited (step S17). If not reached (S17: YES), the process returns to S12 by loop 2.

If it has been reached (S17: NO), it is determined whether or not no has reached N + 1, that is, whether or not the frequency f _N has been received (step S18). If not reached (S18: YES), the process returns to S15 by loop 3. If it has been reached (S18: NO), the process ends. Note that the above-described operation can also be realized by using an interrupt operation due to the start of reception signal input.

(Fourth embodiment)
FIG. 11 is a diagram illustrating frequency characteristics of the surface acoustic wave of the IDT in the touch panel device according to the first embodiment described above. Each center frequency f _n-1 of the excitation, f _n, the center frequency of each received for _{f n + 1 f n-1} , f n, f n + 1 is 1: corresponds at 1, this 1: Each propagation path is separated and specified by one correspondence. Here, not only the reception result corresponding to the center frequency but also the interpolated reception result corresponding to other frequencies that are intermediate frequencies thereof can be used to detect the contact position with higher accuracy.

  In the fourth embodiment, one receiving element 3 is configured to be paired with a plurality of excitation elements 2. FIG. 12 is a diagram illustrating frequency characteristics of IDT surface acoustic waves in the touch panel device according to the fourth embodiment. Broadband frequency characteristics are realized on the receiving side with respect to the excitation frequency. Accordingly, it is possible to obtain an interpolation reception result instead of 1: 1 correspondence as shown in FIG. Contrary to this example, the same effect can be obtained even if the configuration is such that a wideband frequency characteristic is obtained on the excitation side with respect to the received frequency.

(Fifth embodiment)
FIG. 13 is a diagram illustrating frequency characteristics of IDT surface acoustic waves in the touch panel device according to the fifth embodiment. The center frequency of IDT in the exciting element 2 and the receiving element 3 facing each other is shifted by half of the bandwidth. That is, when the bandwidth is BW between the excitation center frequency f _n and the reception center frequency g _n , the relationship of the following equation (3) is established.
g _n = f _n + BW / 2 (3)
Also in the fifth embodiment, as in the fourth embodiment, an interpolated reception result can be obtained, and the detection accuracy can be increased.

(Sixth embodiment)
FIG. 14 is a schematic diagram showing the arrangement of the excitation element 2 / reception element 3 and the propagation state of the surface acoustic wave in the touch panel device according to the sixth embodiment. In this example, the positions of the IDTs in the excitation element 2 and the receiving element 3 are physically shifted, and as in the fourth and fifth embodiments, an interpolated reception result is obtained to increase detection accuracy. I try to get it. In the example shown in FIG. 14, only half of the IDT opening width is shifted.

(Seventh embodiment)
FIGS. 15A, 15B, and 15C show the excitation elements in the touch panel device of the seventh embodiment in which the excitation elements 2 / receiving elements 3 are configured in a plurality of stages for the same purpose as in the sixth embodiment. 2 is a schematic diagram showing the arrangement of the receiving element 3 and the propagation state of the surface acoustic wave. FIG. 15A shows an example in which the excitation element 2 and the reception element 3 are configured in two stages by shifting them forward and backward. FIG. 15B is an example in which the excitation element 2 and the reception element 3 are similarly configured in two stages and the propagation time of the surface acoustic wave is made constant. In this example, no phase shift occurs in each surface acoustic wave. FIG. 15C is an example in which the scanning direction of excitation in the excitation element 2 and the reception direction in the reception elements 3 in a plurality of stages are designed in the same direction.

(Eighth embodiment)
FIG. 16 is a diagram illustrating an electrode configuration of the IDT 2a (3a) when the number of electrodes of each IDT 2a of the excitation element 2 (each IDT 3a of the receiving element 3) is constant. When the frequency is changed with the logarithm of the electrode being constant, the wavelength changes, so the distance between the electrodes changes. As a result, the total length of each IDT 2a (3a) also changes, and the total length becomes longer on the low frequency (long wavelength) side. In this example, since the band ratio with respect to the frequency is determined by the logarithm of the electrodes, the bandwidth on the low frequency side is set in order to realize a frequency change with a constant pitch. Therefore, the apparatus configuration is increased in size. FIG. 17 is a diagram showing an electrode configuration of the IDT 2a (3a) when the frequency change is performed with a certain width. In this example, the logarithm of the electrode in each IDT 2a (3a) is variable, and the logarithm is changed so that the frequency shift amount is constant. Therefore, the total length of each IDTIDT 2a (3a) can be suppressed to a predetermined length or less, and the apparatus configuration can be reduced in size.

(Ninth embodiment)
FIG. 18 is a schematic diagram showing the basic configuration of the touch panel device according to the ninth embodiment. In addition to a pair of excitation elements 2 / receiving elements 3 shown in FIG. 1, another pair of excitation elements 2 and receiving elements 3 are arranged in a manner facing each other at both ends of the substrate 1. Pairs are formed in an array. As described above, in the ninth embodiment, two pairs of the excitation element 2 / reception element 3 are arranged in an orthogonal manner, so that the two-dimensional contact position of the object can be detected.

[First example]
FIG. 19 is a diagram illustrating a driving state in the first example of the ninth embodiment. In this example, the excitation process at the excitation element 2 in each group is performed independently, and the reception process at the reception element 3 in each group is also performed independently. Therefore, these processes can be easily performed.

  Next, a description will be given of second to fourth examples in which the circuit is simplified by sharing the processing in each group.

[Second example]
FIG. 20 is a diagram illustrating a driving state in the second example of the ninth embodiment. In this example, the drive circuits for the two sets of excitation elements 2 are shared. One set of excitation elements 2 and the other set of excitation elements 2 are sequentially excited at the same timing with center frequencies f ₁ , f ₂ ,..., F _n . Therefore, since the frequency scanning can be performed simultaneously, the processing time can be shortened.

[Third example]
FIG. 21 is a diagram illustrating a driving state in the third example of the ninth embodiment. In this example, both sets of excitation elements 2 are connected to the same common electrode 4. After sequentially exciting one set of excitation elements 2 at center frequencies f ₁ , f ₂ ,..., F _n , the other set of excitation elements 2 is set to center frequencies f _{n + 1} , f _{n + 2} ,. , F _2n are sequentially excited. As in the first example, surface acoustic waves in two directions do not occur at the same time and are not easily affected by noise.

[Fourth example]
FIG. 22 is a diagram illustrating a driving state in the fourth example of the ninth embodiment. In this example, similarly to the third example, both sets of excitation elements 2 are connected to the same common electrode 4, and both sets of receiving elements 3 are also connected to the same common electrode 5. The simplification of the circuit configuration can be maximized.

(Tenth embodiment)
FIGS. 23A and 23B are diagrams showing a method for determining the contact position based on the level of the received signal at each receiving element 3. In the figure, the broken line is a threshold level for determining the presence or absence of attenuation of the surface acoustic wave. In this example, the level of the received signal at the receiving element 3 at the center frequencies f ₄ , f ₅ , f ₆ and f ₇ is this. The four propagation paths are within the contact range. For such a reception level pattern, the contact position is determined by the following three methods.

As shown in FIG. 23 (a), the center position P ₁ of the four propagation path which the surface acoustic waves are blocked as a contact position. Alternatively, as shown in FIG. 23A, the center P ₂ of the propagation path at the center frequency f ₅ having the largest attenuation is set as the contact position as the position where the maximum pressure is applied. Alternatively, as shown in FIG. 23B, the center-of-gravity position P ₃ calculated based on the attenuation amounts in the four propagation paths is set as the contact position.

FIG. 24 is a diagram illustrating a moving direction vector for estimating finger movement. In the figure, S indicates a two-dimensionally detected finger contact range, and the coordinates of the center C thereof are (X _C , Y _C ). In addition, the coordinates of the center of gravity G calculated based on the attenuation amount of the obtained reception signal are set to (X _G , Y _G ). Here, a vector having the start point as the center C and the end point as the center of gravity G is defined as a movement direction vector. By obtaining the direction of the moving direction vector (vector CG), the direction related to the finger movement can be estimated.

  By the way, in each of the above-described embodiments, the contact position is detected by the difference in the center frequency of the surface acoustic wave. However, since the surface acoustic wave is a sound wave and relatively slow, It is also possible to detect the contact position by using it. Such an example will be described as the following 11th to 15th embodiments.

(Eleventh embodiment)
FIG. 25 is a diagram illustrating an arrangement example of the excitation element 2 and the reception element 3 of the touch panel device according to the eleventh embodiment. A plurality of excitation elements 2 made of IDT and piezoelectric thin films are formed in one end of the substrate 1 in a stepped manner. A plurality of receiving elements 3 are arranged in a stepped manner on the other end portion of the substrate 1 such that each of the receiving elements 3 faces each excitation element 2. Therefore, the distance between the exciting element 2 and the receiving element 3 facing each other is different in each pair. In this example, the step between adjacent excitation elements 2 / receiving elements 3 is the IDT length.

  Next, the operation will be described. Each excitation element 2 is excited simultaneously at the same center frequency. The surface acoustic waves excited from the respective excitation elements 2 are propagated through the substrate 1 and received by the respective receiving elements 3 facing each other. Here, since the distance between the excitation element 2 and the reception element 3 is different in each pair, the reception timing at each reception element 3 is different, and when those reception signals are detected in time series, as shown in FIG. Thus, each propagation path can be distinguished. Therefore, since the propagation path in which the received signal is attenuated can be specified, the contact position of the object can be detected as in the above-described embodiments.

(Twelfth embodiment)
FIG. 27 is a diagram illustrating an arrangement example of the excitation element 2 and the reception element 3 of the touch panel device according to the twelfth embodiment. The step between the adjacent excitation element 2 / reception element 3 is half the length of the IDT. Therefore, compared with the eleventh embodiment, the arrangement area of the excitation element 2 and the receiving element 3 is narrowed, and the configuration can be reduced in size. The detection operation is the same as in the eleventh embodiment.

(13th Embodiment)
FIG. 28 is a diagram illustrating an arrangement example of the excitation element 2 and the reception element 3 of the touch panel device according to the thirteenth embodiment. A plurality of excitation elements 2 are formed on one end of the substrate 1 in a staircase pattern by sequentially shifting by the length of the IDT. A common receiving element 3 is formed at the other end of the substrate 1. The distance from each excitation element 2 to the receiving element 3 is different from each other. In this example, a surface acoustic wave is received by one receiving element 3 having a common IDT having an opening having the same size as the length of all the excitation elements 2. The detection operation is the same as in the eleventh embodiment. In the thirteenth embodiment, a plurality of receiving elements 3 are arranged in a stepped manner, and a surface acoustic wave is generated by one excitation element 2 having a common IDT having a large opening. You may comprise so that it may excite. In this case, the beam property of the surface acoustic wave can be improved.

(14th Embodiment)
FIG. 29 is a diagram illustrating the configuration of the touch panel device according to the fourteenth embodiment. A plurality of excitation / reception elements 6 for performing excitation and reception of surface acoustic waves are sequentially arranged at one end portion of the substrate 1 by the length of the IDT in a stepped manner. A reflective member 7 is formed on the other end surface of the substrate 1. The distances from the respective excitation / reception elements 6 to the reflecting member 7 are different from each other. Each excitation / reception element 6 is connected to a common electrode 8 for excitation / reception. In this example, the surface acoustic wave is reflected and reflected by the reflecting member 7 so that the surface acoustic wave can be excited and received by the same excitation / reception element 6. Since there is a propagation delay in which the surface acoustic wave reciprocates once through the substrate 1, the drive system for the excitation process and the reception process can be easily switched. In order to avoid the influence of noise, a time gate corresponding to the delay time is applied.

(Fifteenth embodiment)
In the touch panel device configured to detect the contact position using the propagation time difference of the surface acoustic wave, in order to increase the propagation time difference in order to increase the detection accuracy, the surface acoustic wave is applied in the oblique direction of the substrate 1. It is preferable to arrange the excitation element 2 and the reception element 3 so as to propagate. In this case, the arrangement density of the excitation elements 2 and the reception elements 3 can be increased, and the detection performance can be improved. 30 to 33 are diagrams showing examples of arrangement of the excitation element 2 and the reception element 3 of the touch panel device according to the fifteenth embodiment. In any case, a surface acoustic wave propagation path is formed at an angle of 45 ° with respect to the side direction of the substrate 1, and a two-dimensional contact position can be detected.

  In the first example of FIG. 30, the input is separated and the output is added. In the second example of FIG. 31, the input is the same and the output is separated. In the third example of FIG. 32, input and output are added. In the fourth example of FIG. 33, input and output are added using IDTs having different center frequencies. Since some propagation paths have the same propagation time in the X direction and the Y direction, the propagation frequency is easily separated and specified by changing the center frequency.

  In the above-described embodiment, the non-piezoelectric substrate is used. However, a piezoelectric substrate such as quartz may be used.

It is a schematic diagram which shows the basic composition of a touchscreen apparatus. It is sectional drawing which shows the manufacturing process of an excitation element and a receiving element. It is a figure which shows the time series of the excitation signal in an excitation element, and the received signal in a receiving element. It is a flowchart which shows the operation processing in MPU. It is a timing chart which shows the excitation / reception process in 1st Embodiment. It is a timing chart which shows the excitation / reception process in 2nd Embodiment. It is a schematic diagram which shows the propagation state of the surface acoustic wave in 2nd Embodiment. It is a timing chart which shows the excitation / reception process in 3rd Embodiment. It is a schematic diagram which shows the propagation state of the surface acoustic wave in 3rd Embodiment. It is a flowchart which shows the operation | movement procedure in MPU in 2nd, 3rd embodiment. It is a figure which shows the frequency characteristic of the surface acoustic wave of IDT in 1st Embodiment. It is a figure which shows the frequency characteristic of the surface acoustic wave of IDT in 4th Embodiment. It is a figure which shows the frequency characteristic of the surface acoustic wave of IDT in 5th Embodiment. It is a schematic diagram which shows the arrangement | positioning of the excitation element / reception element in 6th Embodiment, and the propagation state of a surface acoustic wave. It is a schematic diagram which shows the arrangement | positioning of the excitation element / receiving element and the propagation state of a surface acoustic wave in 7th Embodiment. It is a figure which shows the electrode structure of IDT when the logarithm of the electrode in each IDT is made constant. It is a figure which shows the electrode structure of IDT when performing a frequency change by a fixed width | variety in 8th Embodiment. It is a schematic diagram which shows the basic composition of 9th Embodiment. It is a figure which shows the drive state in the 1st example of 9th Embodiment. It is a figure which shows the drive state in the 2nd example of 9th Embodiment. It is a figure which shows the drive state in the 3rd example of 9th Embodiment. It is a figure which shows the drive state in the 4th example of 9th Embodiment. It is a figure which shows the contact position determination based on the level of a received signal. It is a figure which shows the movement direction vector for estimating a motion of a finger | toe. It is a figure which shows the example of arrangement | positioning of the excitation element and receiving element in 11th Embodiment. It is a figure which shows the time series of the received signal in 11th Embodiment. It is a figure which shows the example of arrangement | positioning of the excitation element and receiving element in 12th Embodiment. It is a figure which shows the example of arrangement | positioning of the excitation element and receiving element in 13th Embodiment. It is a schematic diagram which shows the basic composition of 14th Embodiment. It is a figure which shows the example of arrangement | positioning of the excitation element and receiving element in the 1st example of 15th Embodiment. It is a figure which shows the example of arrangement | positioning of the excitation element and receiving element in the 2nd example of 15th Embodiment. It is a figure which shows the example of arrangement | positioning of the excitation element and receiving element in the 3rd example of 15th Embodiment. It is a figure which shows the example of arrangement | positioning of the excitation element in the 4th example of 15th Embodiment, and a receiving element.

Explanation of symbols

1 Non-piezoelectric substrate 2 Excitation element 3 Receiving element

Claims (1)

A substrate,
A plurality of excitation elements provided on the substrate, each for exciting a surface acoustic wave;
A plurality of receiving elements that are provided on the substrate to face the plurality of excitation elements, respectively, and each receive a surface acoustic wave;
A surface acoustic wave is propagated to the substrate between the exciting element and the receiving element facing each other, and a receiving position of the surface acoustic wave at the receiving element is within a predetermined level, and a center position of the receiving element. A touch panel device characterized by detecting a direction of a vector connecting a position obtained based on a reception level of a surface acoustic wave.

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