Tactile sense presentation device, tactile sense presentation touch panel and tactile sense presentation method

Abstract

To provide a technique that enables an electrostatic tactile sense and an electric tactile sense to coexist.SOLUTION: One of tactile sense presentation devices according to the present invention comprises: pluralities of first electrodes and second electrodes which are arranged on a substantially flat surface; and an electric power supply part which supplies the first electrode with a first signal including a plurality of pulses rising or falling between a ground potential and a first potential, and also supplies the second electrode with a second signal shifting in phase such that a period in which the first electrode is at the ground potential and a period in which the second electrode is at the first potential overlap, and also having the same waveform with the first signal.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a tactile presentation device, a tactile presentation touch panel, and a tactile presentation method.

Background Art

[0002] In mobile information terminals such as smartphones, it is important to present tactile information in a form superimposed on visual information. At present, it is widely practiced to present a click feeling or the like by vibration. Furthermore, for example, by modulating the frictional feeling of the screen, applications such as expressing a "writing feel" as if writing with a pencil or crayon, and expressing an interaction with a character on the screen by presenting a movement or a spatial pattern are conceivable. There is a strong constraint on tactile presentation superimposed on such an information terminal screen that "it must not block the screen (visual information)". For this reason, mechanical dot matrix displays and the like cannot be used. In addition to the aforementioned vibration presentation, electrostatic touch and electro-tactile using a transparent electrode can be mentioned.

[0003] Regarding a method of generating an electrical stimulus, for example, Non-Patent Document 1 shows a wearable tactile rendering system that achieves both high spatial resolution and high refresh rate by a current control type super-resolution stimulation technology that has not been developed so far.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Non-Patent Document 1 proposes a high-spatial-resolution tactile display device as a method for utilizing electrocutaneous sensation, but does not assume tactile presentation by electrostatic sensation. Therefore, an object of the present invention is to provide a technology capable of coexisting electrostatic sensation and electrocutaneous sensation.

Means for Solving the Problems

[0006] To solve the above problems, one of the typical tactile display devices of the present invention includes a plurality of first electrodes and second electrodes respectively arranged on a substantially flat surface, and a first signal including a plurality of pulses that rise or fall between a ground potential and a first potential is supplied to the first electrode, and for the second electrode, the phase is changed so that the period during which the first electrode is at the ground potential and the period during which the second electrode becomes the first potential overlap, and a power supply unit that supplies a second signal having the same waveform as the first signal.

Effects of the Invention

[0007] According to the present invention, electrostatic sensation and electrocutaneous sensation can coexist. Problems, configurations, and effects other than those described above will be clarified by the description in the embodiments for carrying out the following invention.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

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Figure 5

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Figure 12

DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited by this embodiment. In the description of the drawings, the same parts are denoted by the same reference numerals.

[0010] (Prior Art Example) Referring to FIG. 1, as a prior art example, a method of generating an electrical stimulation in a touch panel will be described. FIG. 1 is a diagram schematically showing the mechanism by which an electrical stimulation is generated. FIG. 1(a) shows the case of electrostatic touch, and FIG. 1(b) shows the case of electro-tactile. In the present disclosure, the case where touch occurs at the fingertip as a part of the human body will be described, but the present disclosure is not limited to this case. The present disclosure can also be applied to parts of the human body other than the fingertip.

[0011] Electrostatic touch involves accumulating charges by covering the surface of an electrode with a high voltage with an insulator layer, generating an attractive force between the skin. Since electrostatic touch generates a physical adsorption force, the resulting change in frictional force also occurs physically, making it possible to present a natural change in the sense of friction. By presenting such a change in the sense of friction, it becomes possible to express the "writing feel" as if writing with a pencil or crayon, or to present movement and spatial patterns to the user. As shown in Fig. 1(a), the touch panel 1a has a structure in which a conductor layer 2 and an insulator layer 3 are arranged on the display panel 1. When positive charges are stored in the conductor layer 2, when a part of the human body (for example, the fingertip 20) approaches the touch panel 1a, the insulator layer 3 functions as a capacitor, and negative charges are attracted to the surface of the fingertip 20. A Coulomb force is generated between the positive charges in the conductor layer 2 and the negative charges in the fingertip 20, affecting the tactile receptors inside the fingertip 20, and the user feels the touch.

[0012] On the other hand, electro-tactile involves directly stimulating the sensory nerves by the current flowing from an electrode with a high voltage into the skin. Especially since the skin of the fingertip has a thick stratum corneum, a voltage of 200 V or more is often required. Electro-tactile can present tactile sensations with a high resolution of about 2 mm and can express shapes and movements. As shown in Fig. 1(b), the touch panel 1b has a structure in which a plurality of electrodes 5 are arranged on the display panel 1. For example, a pulsed voltage is applied to the electrodes 5. When the fingertip 20 touches the touch panel 1b, a current is generated between the plurality of electrodes 5 in contact with the fingertip 20, affecting the tactile receptors inside the fingertip 20, and the user feels the touch.

[0013] As described above, both electrostatic haptics and electro-tactile haptics are promising methods for presenting haptic sensations on a display screen, and although both are realized by electronic circuit technology, they have been regarded as completely different haptic presentation means. The former controls physical frictional force, while the latter is a direct stimulation of nerves. The former has electrodes covered with an insulator layer, while the latter does not. Rather, in electrostatic haptics, it is also considered necessary for safety that the presence of an insulator layer prevents the generation of electrical stimulation. A very rare example of simultaneously realizing electrostatic haptics and electro-tactile haptics was one in which "electrodes coated with an insulator for electrostatic haptics" and "exposed electrodes for electro-tactile haptics" were arranged alternately.

[0014] In contrast, the focus of the present invention is directed towards the unification, integration, and combination of these two stimulation methods. In recent years, a method for realizing electro-tactile haptics at a relatively low voltage (±30 V or less) has been proposed (for example, Non-Patent Document 1). However, during the inventors' retesting of the method, it was confirmed that not only electrical stimulation is generated, but when a finger is moved on the electrode, a frictional vibration sensation peculiar to electrostatic haptics may clearly occur. As will be described later, this is presumed to be a phenomenon caused by the accumulation of charges in the stratum corneum of the skin during electrical stimulation.

[0015] In the present disclosure, it is shown that neuroelectrical stimulation and electrostatic stimulation can be simultaneously achieved by stimulation from the same electrode. As for the system configuration, a pulse width modulation (PWM) waveform is used instead of the amplitude modulation (AM) waveform used in conventional low-voltage electrical stimulation. Thus, in the present disclosure, it is also simultaneously shown that stimulation can be performed without problems using such a modulation method.

[0016] (Embodiment) (Principle) (Low-Voltage Electrical Stimulation and PWM Driving) Next, referring to FIG. 2, the outline of Non-Patent Document 1 will be described. FIG. 2 is a diagram showing the outline of the stimulation waveform of low-voltage electrical stimulation in Non-Patent Document 1 and the actual waveform during the follow-up test conducted by the inventor. Here, the waveform of the voltage input to the channel (power supply path) to which the electrode is connected is referred to as the stimulation waveform. As the stimulation waveform, a sine wave of about 50 Hz (see FIG. 2(c)) modulated by a rectangular wave of about 10 kHz (see FIG. 2(d)) is used, and stimulation waveforms of opposite polarities are input to two (or more) electrodes 15. As shown in FIG. 2(a), during the inventor's follow-up test, electrodes with a diameter Φ1 of 2.0 mm and a center-to-center distance D1 of 3.0 mm were used as electrodes, and the fingertip 20 was stimulated. When setting a channel for each electrode, for example, when +30 V is applied to one channel (CH1 in FIG. 2(b)), -30 V is applied to the other channel (CH2 in FIG. 2(b)). Therefore, as the potential difference ((voltage of the electrode to which CH1 is connected) - (voltage of the electrode to which CH2 is connected)), a stimulation of 60 V is applied. When modulating a sine wave of 50 Hz, the repetition of the strength of the stimulation becomes 100 Hz, so the stimulation is generated as a vibration of 100 Hz. Note that FIG. 2(d) shows a waveform obtained by superimposing the stimulation waveform input to CH1 and the stimulation waveform input to CH2. Also, FIG. 2(c) shows a waveform obtained by modulating the stimulation waveform using a sine wave.

[0017] Since the method shown in this Non-Patent Document 1 needs to drive a plurality of channels positively and negatively and output an analog waveform, the circuit configuration becomes somewhat complicated (in the method of Non-Patent Document 1, analog switches that can be driven by positive and negative voltages are prepared in the number of channels, and two voltage outputs are prepared).

[0018] On the other hand, it is possible to generate an equivalent stimulus by a PWM waveform. FIG. 3 is a diagram showing a schematic diagram of a waveform generated using a PWM waveform. In this case, a single power supply with a voltage twice as high can be prepared as the power supply, and switches for connecting each channel to either the power supply or the ground are required for the number of channels, but the circuit is much simpler than the aforementioned circuit. As shown in FIG. 3(a), a single power supply of 60 V is connected to CH1, and another single power supply of 60 V is connected to CH2, and a voltage of the PWM waveform is supplied from each channel. The upper part of FIG. 3(b) shows the stimulus waveform applied to CH1 or CH2, and the lower part of FIG. 3(b) shows the potential difference ((voltage of the electrode to which CH1 is connected) - (voltage of the electrode to which CH2 is connected)). Although there is a difference between the analog waveform and the digital waveform in the potential difference shown in FIG. 2(c) and the potential difference shown in the lower part of FIG. 3(b), it was confirmed in a preliminary study that similar tactile sensations due to electrical stimulation can also be generated by this method.

[0019] (Principle and Possibility of Coexistence with Electrostatic Tactile Presentation) Next, referring to FIG. 4, the principle considered in the stimulation method in the present disclosure is shown. FIG. 4 is a diagram showing the principle considered in this stimulation method. FIG. 4(a) shows the relationship between the fingertip and the electrode as an equivalent circuit, and FIG. 4(b) shows the case where a potential difference occurs in the equivalent circuit.

[0020] In many studies, the human skin is represented by a parallel circuit of the capacitance and resistance of the stratum corneum and the resistance of the deep part. Since the resistance of the stratum corneum is relatively high, first, this is ignored and considered. As shown in FIG. 4(a), the capacitance between the electrode of CH1 and the stratum corneum is represented as C1, and the capacitance between the electrode of CH2 and the stratum corneum is represented as C2, respectively. Also, the skin resistance existing between the two capacitances is denoted as R1. The AC power supply connected between CH1 and CH2 is represented as E1.

[0021] The low-voltage stimulation described with reference to FIG. 3 uses a modulated wave with a high frequency (10 kHz). As shown in FIG. 4(b), within one period of this modulated wave, a unidirectional current flows for 50 μs in the first half to charge the capacitance of the skin, and a reverse current of 50 μs flows in the second half. At this time, considering the potential difference due to the charge accumulated in the capacitance in the first half, as a result, a potential difference of 120 V is instantaneously generated across the resistance under the skin by the repetitive waveform of ±30 V.

[0022] The above is a very simplified explanation, but from here, the advantages and limitations of the stimulation method in the present disclosure can be understood. First, since a high potential difference is generated across the resistance part under the skin, stimulation can be performed without relying on the high resistance of the horny part on the skin surface. Also, here the horny part of the skin is represented only by capacitance, but in reality, the charge accumulated in the capacitance discharges due to the resistance of the horny part, so this method requires a high frequency. On the other hand, conversely, when using a modulation frequency that is too high, the charging of the nerve membrane of the nerve to be stimulated cannot be sufficiently performed, so it is considered that nerve stimulation does not occur. Thus, it is expected that there is an optimal value for the modulation frequency. Also, this stimulation method can be said to be a method that utilizes the capacitance component of the skin, and it is considered preferable to generate stimulation for sites with a thick horny layer such as finger skin.

[0023] As described above, if this stimulation method is understood as a method of "efficiently performing stimulation under the skin keratin by charging and discharging the capacitance component of the skin", as another possibility, it can be predicted that "attraction to the electrode occurs due to the charge accumulated in the capacitance of the skin". That is, this stimulation method is considered to be a method that can coexist not only with neuroelectrical stimulation but also with electrostatic tactile stimulation. Hereinafter, the hypothesis that "electrical tactile sensation (tactile presentation by neuroelectrical stimulation) and electrostatic tactile sensation (tactile presentation by electrostatic force) can be realized simultaneously" will be confirmed by experiments.

[0024] (Experimental apparatus) Next, with reference to FIGS. 5 and 6, the structure of the experimental apparatus will be described. FIG. 5 is a diagram showing the structure of the experimental apparatus. FIG. 6 is a diagram showing a photograph of the electrode portion of the experimental apparatus. The experimental apparatus includes a plurality of first electrodes and a plurality of second electrodes respectively arranged substantially on a plane, and supplies a first signal including a plurality of pulses that rise or fall between a ground potential and a first potential to the first electrode, and for the second electrode, the phase is changed so that the period during which the first electrode is at the ground potential and the period during which the second electrode is at the first potential overlap, and a power supply unit that supplies a second signal having the same waveform as the first signal, and functions as a tactile presentation device. Further, the power supply unit includes a switch unit (switch 110) that switches the potentials of the first electrode and the second electrode to either the ground potential or the first potential, and controls the switch unit to make the first electrode be in the first state where the first electrode is at the first potential and the second electrode is at the ground potential, the second state where the first electrode is at the ground potential and the second electrode is at the first potential, and the third state where the first electrode is at the ground potential and the second electrode is at the ground potential, and a control unit (microcontroller 104) that generates a switch state control signal for switching between them. In other words, a waveform signal composed of a plurality of pulses is supplied to the first electrode between the ground potential and the first potential, and for the second electrode, the supply of a waveform signal having the same waveform as the waveform signal composed of the plurality of pulses is started during the period when the first electrode is at the ground potential between the first pulse and the second pulse of the plurality of pulses, and the waveform signal composed of the plurality of pulses is alternately supplied to the first electrode and the second electrode. This will be specifically described below.

[0025] As shown in FIG. 5, the experimental apparatus 100 is composed of a PC 102, a microcontroller (ESP32-DevkitC, Espressif Systems) 104, a step-up DC-DC converter (B0524M-2WR3, MORNSUN) 106, an AD converter for current measurement (AD7476, Analog Devices) 108, a switch (HV513, Microchip Technologies) 110, and an electrode unit 112. Further, as shown in FIG. 6, the electrode unit 112 includes electrodes arranged in an 8×8 matrix with a diameter of 2.0 mm and a center-to-center distance of 2.54 mm. The DC-DC converter 106 realizes a voltage of about 80 V by connecting three 24V output converters in series. The stimulation current can be monitored by measuring the voltage through the resistor of the AD converter 108. The switch 110 has eight pairs of upper and lower switches built-in, and the state of each electrode can be switched between the power supply side and the ground side. Also, the state of each electrode can be inverted quickly and simultaneously by a signal (switch state control signal) to the POL terminal (polarity control terminal) of the switch 110. Note that the above case is described as an example of the experimental apparatus, but the present disclosure is not limited to this case. For example, the voltage may be in the range of 30V or more and 100V or less. Also, the center-to-center distance of the electrodes may be in the range of 1 mm or more and 10 mm or less.

[0026] In the experiment described later, during the experiment that requires the subject's response, nothing is worn on the finger. However, when actually measuring the physical vibration that occurs, an acceleration sensor (BMX055, Bosch) was mounted on the nail and fixed with double-sided tape. The acceleration was measured only in the vertical direction at a sampling rate of about 760 Hz.

[0027] (Experimental Procedure) Next, with reference to FIGS. 7 and 8, the experimental procedure will be described. The purpose of this experiment is to verify that electrocutaneous sensation and electrostatic sensation can be realized simultaneously.

[0028] FIG. 7 is a schematic diagram of a stimulation pattern (first signal). FIG. 7(a) shows the change pattern of the polarity of each electrode included in the electrode unit 112, and FIG. 7(b) shows the stimulation waveform (stimulation pattern) for each electrode. The first signal includes a first signal section including a plurality of pulses and a first ground section that is equal to the ground potential without including a plurality of pulses, and one cycle consisting of the first signal section and the first ground section is defined as the first oscillation period. Specifically, as shown in FIG. 7(a), each electrode included in the electrode unit 112 is connected in a striped pattern to an anode (+80V (first potential), also referred to as an anode) and a cathode (ground (ground potential), also referred to as a cathode). As shown in FIG. 3, this switching is performed at a high modulation frequency described later, and the strength of the signal is expressed by PWM. In this case, for the sake of simplifying the experimental setup, a method of modulating a rectangular wave of 125 Hz (first oscillation period) with high-frequency pulses is adopted, and the expression of the signal strength by PWM is not performed. As a result, as shown in FIG. 7(b), a stimulation waveform is obtained in which a rectangular wave pulse train of 4 ms (first signal section) and a rest period of 4 ms (first ground section) are repeated. Note that the rectangular wave of 125 Hz is an example, and the present disclosure is not limited to this case. The frequency of the rectangular wave can be, for example, in the range of 20 Hz or more and 300 Hz or less. Further, in FIG. 7(a), when assuming a rectangle (a square connecting four vertices) forming a lattice pattern, it is also possible that the first electrode and the second electrode are arranged at both ends of one side of the rectangle. The first electrode and the second electrode may be arranged on the diagonal of the rectangle as described later.

[0029] As the modulation frequencies, rectangular waves of 50 kHz, 25 kHz, 10 kHz, 5 kHz, 2.5 kHz, 1 kHz, and 500 Hz were used. At this time, the switching between the anode and cathode in FIG. 7 (the pulse width of the rectangular wave pulse train) was performed at 10 μs, 20 μs, 50 μs, 100 μs, 200 μs, 500 μs, and 1 ms (hereinafter referred to as the pulse width). FIG. 8 is a diagram showing an actual stimulation pattern (waveform) (in the case of a pulse width of 200 μs). Note that the present disclosure is not limited to this case. For example, the switching between the cathode and anode can be in the range of 10 μs or more and 5 ms or less. Note that the pulse width included in the pulse train is not limited to one case, and a pulse train with pulse width modulation can also be used. In other words, the pulse widths of a plurality of pulses included in the pulse train may be different within the range of 10 μs or more and 5 ms or less.

[0030] The experimental procedure is as follows. First, the index finger of the subject's dominant hand and the electrode were wiped with absolute ethanol and dried. Also, the electronic scale was pressed with the finger, and the subject was instructed to set the finger pressing force to about 50 g in the subsequent experiment. Next, one of the seven modulation frequencies was selected, and the subject was made to experience the state of placing the finger on the electrode and keeping it stationary and the state of tracing the electrode surface. By doing this for all modulation frequencies, the types of sensations obtained and the range of intensity were made understood by the subject.

[0031] This experiment was conducted as follows. One of the seven modulation frequencies was selected, the finger was placed on the electrode and kept stationary, and the subject was asked whether a tactile sensation was generated. As the types of tactile sensations, pressure sensation and vibration sensation were prepared, and the subject was asked to answer on a 5 - point Likert scale regarding the clarity of each sensation (1: not felt at all, 2: faintly felt, 3: clearly felt weakly, 4: clearly felt, 5: strongly felt). Subsequently, the finger was moved on the electrode to draw a circle, and the subject was similarly asked about the presence or absence and intensity of the pressure sensation and vibration sensation. The speed of drawing the circle was set to about two rounds per second. For subjects who had difficulty drawing a smooth circle due to friction between the finger and the electrode, a tracing motion by a reciprocating motion was also allowed.

[0032] It was indicated that the tactile sensation to be answered is a pressure sensation or a vibration sensation that is clearly distinguished from the tactile sensation by touching the electrode itself. To clarify this, samples of the same electrode as the stimulating electrode were arranged and the subjects were instructed to compare the tactile sensations if necessary. The above measurements were performed once for each of the seven modulation frequencies. Then, an acceleration sensor was attached to the fingernail, and the acceleration waveforms during tracing movements were recorded for all modulation frequencies.

[0033] The subjects were 7 male subjects aged from 22 to 26 years old (6 right-handed and 1 left-handed). The presentation order of the modulation frequencies was balanced among the subjects. This experiment was conducted after being reviewed by the ethics committee of the university where the author belongs.

[0034] (Experimental results) Next, referring to FIGS. 9 and 10, the experimental results will be described. FIG. 9 is a diagram showing an example of the vertical acceleration measured on the fingernail when a tracing movement of the finger was performed on the electrode. This is the case when a pulse of 50 μs was used. The vertical axis represents the acceleration (G). It can be seen that distinct mechanical vibrations are generated along with the movement of the finger. The observed vibration frequency is 125 Hz, which coincides with the frequency of the pulse train used this time. Thus, it can be said that the mechanical vibration presentation by electrostatic tactile presentation was realized as expected. In this example, the acceleration amplitude was at most 0.4 G, but the amplitude changed greatly depending on the finger pressing force, speed, contact angle, etc.

[0035] FIG. 10 is a diagram showing the results of subjective evaluation. It is a graph of the pressure sensation (FIG. 10(a)) and vibration sensation (FIG. 10(b)) when the finger was not moved, and the pressure sensation (FIG. 10(c)) and vibration sensation (FIG. 10(d)) when a tracing movement of the finger was performed. The horizontal axis represents the pulse width, and the vertical axis represents the clarity score. At the current stage, no statistical test has been performed.

[0036] From the experimental results, it can be seen that when the pulse width is 10 μs, no tactile sensation is generated under any conditions. Regarding the vibration sensation, whether the finger is moved or not, there is a peak around 50 μs to 100 μs. Regarding the pressure sensation, such a peak is not distinct. Also, during the tracing operation, a strong vibration sensation is generated throughout.

[0037] (Discussion) From this experiment, it became clear that even in a situation where direct contact with the electrode is made without using a layer of insulator, mechanical vibrations due to electrostatic force do occur. Also, from the results of the subjective evaluation, it became clear that both pressure sensation and vibration sensation are generated in a wide range of pulse widths, whether the finger is in a stationary state or a tracing operation state. Thus, according to the present disclosure, electrostatic touch and electrocutaneous sensation can coexist, and electrostatic touch and electrocutaneous sensation can be presented to the user (subject).

[0038] (Explanation of Modification Examples) Hereinafter, modification examples will be described. In the following description of the modification examples, the same or equivalent components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof will be simplified or omitted.

[0039] (Modification Example 1) Generally, in electrostatic touch, in order to stabilize the sensation, it is often done to electrically ground another part of the body (for example, in the case of a mobile device, the housing is often used as the grounding part). Therefore, for example, it is also possible to set the potential of the user's body to the ground potential. If the fact that the low-potential electrode and the high-potential electrode existed alternately in this setup led to the instability of electrostatic touch (instability of tactile intensity, difficulty of perception), it is conceivable to stabilize it by providing a grounding electrode externally in the future. Also, in this case, the switching between the electrical stimulus and the electrostatic stimulus may be separated by the presence or absence of the use of an external grounding electrode of the tactile presentation device.

[0040] (Modification Example 2) In the vibration waveform shown in FIG. 9 and the striped electrode arrangement as shown in FIG. 7 used this time, both the tactile sensation caused by electrostatic touch and the tactile sensation caused by electrocutaneous sensation occurred. On the other hand, according to our preliminary study, when the electrode arrangement is changed from a striped pattern to a checkered pattern, it was observed that the tactile sensation caused by electrostatic touch occurs unchanged, while the tactile sensation caused by electrocutaneous sensation becomes clearly weaker. On the other hand, when the electrode group was treated as four 2x2 = 4 electrodes being the same electrode and a larger checkered pattern was used, the electrocutaneous sensation and the electrostatic touch were felt equally strongly. From this, it is considered that there are electrode spatial arrangements suitable for electrostatic touch and electrocutaneous sensation respectively. For example, arranging electrodes in a checkered pattern, changing the electrode size, etc. are conceivable.

[0041] FIG. 11 is a schematic diagram showing another example of a stimulation pattern. FIG. 11(a) shows the change pattern of the polarity of each electrode included in the electrode unit 112, and FIG. 11(b) shows the stimulation waveform for each electrode. The microcontroller 104 can generate a stimulation pattern as shown in FIG. 11 by generating a switch state control signal and controlling the switch 110.

[0042] Specifically, as shown in FIG. 11(a), each electrode included in the electrode unit 112 is connected to an anode (first potential (for example, +80V)) and a cathode (ground (ground potential)) in a checkered pattern. In FIG. 11(a), when assuming a rectangle (a square connecting four vertices) forming a lattice pattern, it is also possible that the first electrode and the second electrode are arranged on the diagonal of the rectangle, as will be described later. Also, as shown in FIG. 11(b), for example, a pulse (rectangular wave) that rises to +80V and falls to ground occurs six times as one vibration cycle, and one vibration cycle is, for example, 20 ms (frequency 50 Hz). The pulse is pulse width modulated (PWM), and the pulse period is 10 μs or more and 500 μm or less.

[0043] Also, FIG. 12 is a schematic diagram showing an example of a stimulation pattern when a plurality of electrodes are treated as an electrode group. FIG. 12(a) shows the change pattern of the polarity of each electrode included in the electrode unit 112, and FIG. 12(b) shows the stimulation waveform for each electrode group.

[0044] As shown in Fig. 12(a), for the electrodes arranged in a lattice pattern in the electrode portion 112, the electrodes arranged at the four vertices of one lattice are treated as one electrode group Egm (m is a positive integer of 1 or more). Also, as shown in Fig. 12(b), the polarities of the electrodes included in one electrode group are controlled to be common. Specifically, the stimulation waveform of the electrode group Eg1 includes a plurality of pulses with pulse width modulation, the stimulation waveform of the electrode group Eg2 has the same stimulation waveform as that of the electrode group Eg1, and the phase is controlled to change so that it becomes the cathode at the timing when the electrode group Eg1 becomes the anode. When controlled in this way, one electrode group can be treated as if it were one electrode, and even if the size of the electrode itself is the same in terms of structure, it is possible to virtually change the size of the electrode in terms of control. Note that the vibration period and the pulse period are shown in the case of being set in the same way as in Fig. 11(b), but the present disclosure is not limited to this case. The vibration period and the pulse period can be set as appropriate.

[0045] As shown in Fig. 12(a), in the change pattern, when a certain electrode group is the anode, the adjacent electrode group becomes the cathode, and after passing through the state where both electrode groups are the cathode, the anode and the cathode are in a state of being swapped. In Fig. 11(a), the polarity was controlled for each electrode to realize a checkered electrode arrangement, but in Fig. 12(a), the polarity is controlled for each electrode group to realize a checkered electrode arrangement.

[0046] It is considered that the electro-tactile sensation in the electrode arrangement of Fig. 11(a) can obtain a greater tactile sensation than the electro-tactile sensation in the electrode arrangement of Fig. 12(a). By adopting such an electrode arrangement, it is considered possible to control the magnitude of the electro-tactile sensation. Note that in the above description, the case of a square lattice and an electrode group including four electrodes has been described, but the present disclosure is not limited to this case. The shape of the lattice and the number of electrodes included in the electrode group can be set as appropriate.

[0047] (Modification 3) The tactile presentation device in the present disclosure can be applied to a touch panel which is an input / output device. The tactile presentation touch panel includes a display in which a first electrode and a second electrode are alternately arranged in a lattice pattern, a detection unit that detects a change in impedance on the display, and the tactile presentation device in the present disclosure. An AD converter 108 can be applied to the detection unit. Since electrostatic touch and electro-tactile can be presented according to a user's input operation, it is possible to improve the operability of the device.

[0048] (Modification and others) Although the case of obtaining electrostatic touch by tracing the electrodes arranged on a plane has been described, the present disclosure is not limited to this. For example, it is also possible to provide a tactile sensation by arranging electrodes on a glove-shaped device and changing the electrode arrangement without moving the fingers. In the field of xR (cross reality), it is conceivable to provide visual information to a user by a head-mounted display and provide tactile information by a glove-shaped device.

[0049] (Conclusion) In this study, it was shown that neuroelectrical stimulation and electrostatic stimulation can be simultaneously established by stimulation from the same electrode. It was also shown that tactile presentation can be achieved with a simple system configuration by using a pulse width modulation waveform instead of the AM modulation waveform used in the low-voltage electrical stimulation of previous studies.

[0050] As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present invention.

[0051] Aspects that can be the content of the present invention are described below, but are not limited thereto. (Aspect 1) A plurality of first electrodes and second electrodes respectively arranged on a substantially plane, A tactile presentation device comprising: a power supply unit that supplies a first signal including a plurality of pulses that rise or fall between a ground potential and a first potential to the first electrode, and supplies a second signal having the same waveform as the first signal to the second electrode, wherein the phase of the second signal is changed such that a period during which the first electrode is at the ground potential and a period during which the second electrode is at the first potential overlap. (Aspect 2) The power supply unit includes a switch unit that switches the potentials of the first electrode and the second electrode to either the ground potential or the first potential, and a control unit that controls the switch unit to generate a switch state control signal for switching between a first state in which the first electrode is at the first potential and the second electrode is at the ground potential, a second state in which the first electrode is at the ground potential and the second electrode is at the first potential, and a third state in which the first electrode is at the ground potential and the second electrode is at the ground potential; the tactile presentation device according to Aspect 1. (Aspect 3) When the first signal includes a first signal section including the plurality of pulses and a first ground section that is equal to the ground potential and does not include the plurality of pulses, and one cycle consisting of the first signal section and the first ground section is defined as a first oscillation period, the first oscillation period is in the range of 20 Hz or more and 300 Hz or less; the tactile presentation device according to Aspect 1 or Aspect 2. (Aspect 4) The pulse width of the pulses included in the plurality of pulses is in the range of 10 μs or more and 5 ms or less, and the pulse widths of the plurality of pulses may be different from each other within this range; the device according to any one of Aspects 1 to 3. (Aspect 5) The first potential is 30 V or more and 100 V or less; the device according to any one of Aspects 1 to 4. (Aspect 6) The center-to-center distance between the first electrode and the second electrode is in the range of 1 mm or more and 10 mm or less; the tactile presentation device according to any one of Aspects 1 to 5. (Aspect 7) The tactile presentation device according to any one of Aspects 1 to 6, which presents electrocutaneous sensation and electrostatic sensation to a user. (Aspect 8) The tactile presentation device according to any one of Aspects 1 to 7, wherein the ground potential is the potential of the user's body. (Aspect 9) A display in which the first electrode and the second electrode are alternately arranged in a grid pattern, A detection unit that detects a change in impedance on the display, A tactile presentation touch panel including the tactile presentation device according to any one of Aspects 1 to 8. (Aspect 10) The tactile presentation touch panel according to any one of Aspects 1 to 9, wherein the first electrode and the second electrode are arranged at both ends of one side of the rectangle forming the grid pattern. (Aspect 11) The tactile presentation touch panel according to any one of Aspects 1 to 10, wherein the first electrode and the second electrode are arranged on the diagonal line of the rectangle forming the grid pattern. (Aspect 12) A tactile presentation method for tactile presentation using a plurality of first electrodes and second electrodes respectively arranged on a substantially flat surface, A first signal including a plurality of pulses that rise or fall between a ground potential and a first potential is supplied to the first electrode, To the second electrode, a second signal having the same waveform as the first signal is supplied, with the phase changed so that the period during which the second electrode becomes the first potential overlaps the period during which the first electrode is at the ground potential.

Explanation of Reference Numerals

[0052] 1: Display panel, 1a, 1b: Touch panel 2: Conductor layer 3: Insulator layer 5, 15: Electrodes 20: Fingertip 100: Experimental device 104: Microcontroller 106: DC-DC Converter 108: AD Converter 110: Switch 112: Electrode Section

Claims

1. A first electrode and a second electrode, each of which is arranged in plurality on a substantially flat surface, a power supply unit that supplies a first signal including a plurality of pulses that rise or fall between a ground potential and a first potential to the first electrode, and supplies a second signal having the same waveform as the first signal to the second electrode, with the phase being changed such that a period during which the first electrode is at the ground potential and a period during which the second electrode is at the first potential overlap; a tactile presentation device comprising the same.

2. The power supply unit a switch unit that switches the potentials of the first electrode and the second electrode to either the ground potential or the first potential, controls the switch unit, a first state in which the first electrode is at the first potential and the second electrode is at the ground potential, a second state in which the first electrode is at the ground potential and the second electrode is at the first potential, a control unit that generates a switch state control signal for switching between a third state in which the first electrode is at the ground potential and the second electrode is at the ground potential; the tactile presentation device according to claim 1, comprising the same.

3. The first signal includes a first signal section including the plurality of pulses and a first ground section that is an interval equal to the ground potential without including the plurality of pulses. When one cycle composed of the first signal section and the first ground section is defined as a first oscillation period, the first oscillation period is in the range of 20 Hz or more and 300 Hz or less; the tactile presentation device according to claim 1.

4. The pulse width of the pulses included in the plurality of pulses is in the range of 10 μs or more and 5 ms or less, and the pulse widths of the plurality of pulses may be different from each other within the range; the device according to claim 1.

5. The first potential is 30 V or more and 100 V or less; the device according to claim 1.

6. The center-to-center distance between the first electrode and the second electrode is in the range of 1 mm or more and 10 mm or less; the tactile presentation device according to claim 1.

7. A tactile presentation device that presents electro-tactile and electrostatic touch sensations to a user; according to claim 1.

8. The ground potential is the potential of the user's body; the tactile presentation device according to claim 7.

9. A display in which the first electrode and the second electrode are alternately arranged in a grid pattern, a detection unit that detects a change in impedance on the display, a tactile presentation touch panel comprising the tactile presentation device of claim 1.

10. The tactile presentation touch panel according to claim 9, wherein the first electrode and the second electrode are arranged at both ends of one side of the rectangle forming the grid pattern.

11. The tactile presentation touch panel according to claim 9, wherein the first electrode and the second electrode are arranged on a diagonal line of the rectangle forming the grid pattern.

12. A tactile presentation method for tactile presentation using a plurality of first electrodes and second electrodes respectively arranged on a substantially flat surface, wherein a first signal including a plurality of pulses rising or falling between a ground potential and a first potential is supplied to the first electrode, and a second signal having the same waveform as the first signal is supplied to the second electrode, with the phase changed so that a period during which the second electrode becomes the first potential overlaps a period during which the first electrode is at the ground potential.

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