Tactile presentation device and tactile presentation method

Abstract

To provide a tactile presentation device and a tactile presentation method that can present a sufficiently strong tactile sensation.SOLUTION: A tactile presentation device 1 includes: a vibration unit 3 constituted by including a piezoelectric element 21 and having a resonance point in a tactile frequency band; and a self-oscillation circuit 5 electrically connected to the vibration unit 3. The piezoelectric element 21 self-oscillates in a frequency band based on a resonance point by a drive voltage input from the self-oscillation circuit 5 in response to contact with the vibration unit 3.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a tactile presentation device and a tactile presentation method. [Background technology]

[0002] A conventional tactile presentation device is described in, for example, Patent Document 1. This conventional tactile presentation device includes a transmission member and a tactile presentation means (piezoelectric element) that generates at least one of a traveling wave and a standing wave in the transmission member. By generating at least one of a traveling wave and a standing wave in the transmission member, tactile information of an object is transmitted to a fingertip of an operator that touches the transmission member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-261738 Summary of the Invention [Problem to be solved by the invention]

[0004] In a tactile presentation device, there is a problem in that vibration utilizing the resonance point of a single piezoelectric element is unsuitable for presenting a tactile sensation because the resonance frequency is too high, making it difficult to present a tactile sensation of sufficient strength.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a tactile presentation device and a tactile presentation method that can present a tactile sensation of sufficient strength. [Means for solving the problem]

[0006] A tactile presentation device according to one aspect of the present disclosure includes a piezoelectric element and a vibration unit having a resonance point in a tactile frequency band, and a self-oscillating circuit electrically connected to the vibration unit, and the piezoelectric element self-oscillates in a frequency band based on the resonance point due to a driving voltage input from the self-oscillating circuit in response to contact with the vibration unit.

[0007] In this tactile presentation device, the vibration unit including the piezoelectric element has a resonance point in the tactile frequency band. The resonance point when the vibration unit is touched is shifted to a lower frequency band compared to the resonance point of the piezoelectric element alone, so that the piezoelectric element that self-oscillates upon receiving a drive voltage from the self-oscillating circuit can generate vibrations in a frequency band where tactile sensations are more easily obtained. Therefore, this tactile presentation device can present a tactile sensation of sufficient strength.

[0008] The piezoelectric element may include a piezoelectric body, a drive electrode, and a feedback electrode. With this configuration, self-oscillation of the piezoelectric element can be easily achieved using the self-oscillation circuit.

[0009] The vibration unit may be configured to include a vibration plate. In this case, the resonance point of the vibration unit can be easily adjusted according to the design of the piezoelectric element and the vibration plate. Therefore, the vibration unit can generate vibrations in a frequency band that is more likely to produce a tactile sensation.

[0010] The self-oscillating circuit may input a plurality of drive voltage values ​​to the piezoelectric element, thereby increasing the variety of tactile sensations provided according to the drive voltage values.

[0011] The initial resonance point of the vibration unit when there is no contact with the vibration unit may be 100 Hz to 500 Hz. This frequency band is a band in which the human body can easily sense tactile sensation as vibration. Therefore, by setting the initial resonance point of the vibration unit in the above range, the vibration unit can generate vibrations in a frequency band in which tactile sensation is more easily felt.

[0012] The resonance point of the vibration unit when the vibration unit is touched may be shifted to a lower frequency side than the initial resonance point. By shifting the resonance point to the lower frequency side, a clearer tactile sensation can be presented.

[0013] The amount of change in the resonance point of the vibration unit when the vibration unit is in contact may increase according to the magnitude of the pressure applied to the vibration unit, thereby making it possible to present various tactile sensations according to the state of contact with the vibration unit.

[0014] A tactile presentation method according to one aspect of the present disclosure uses a vibration unit including a piezoelectric element and having a resonance point in a tactile frequency band, and a self-oscillating circuit electrically connected to the vibration unit, and causes the piezoelectric element to self-oscillate in a frequency band based on the resonance point by a driving voltage input from the self-oscillating circuit in response to contact with the vibration unit.

[0015] In this tactile sensation presentation method, the vibration unit including the piezoelectric element has a resonance point in the tactile frequency band. The resonance point when the vibration unit is touched is shifted to a lower frequency band compared to the resonance point of the piezoelectric element alone, so that the piezoelectric element that self-oscillates upon receiving a drive voltage from the self-oscillating circuit can generate vibrations in a frequency band where tactile sensation is more easily obtained. Therefore, this tactile sensation presentation method can present a tactile sensation of sufficient strength. Effect of the Invention

[0016] According to the present disclosure, a tactile sensation of sufficient strength can be presented. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic cross-sectional view showing a tactile presentation device according to an embodiment of the present disclosure. [Diagram 2] 11 is a diagram showing the relationship between a concave pressure on a panel layer and a variation in a resonance point of a vibrating section. FIG. [Diagram 3] 2 is a diagram showing an example of the configuration of a self-oscillating circuit applied to the tactile presentation device shown in FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, preferred embodiments of a tactile presentation device and a tactile presentation method according to one aspect of the present disclosure will be described in detail with reference to the drawings.

[0019] Fig. 1 is a schematic cross-sectional view showing a tactile presentation device according to an embodiment of the present disclosure. The tactile presentation device 1 shown in Fig. 1 is a device that presents vibrations in response to contact with a finger or the like as a tactile sensation, and can be mounted on electronic devices such as smartphones, tablets, and navigation devices. As shown in Fig. 1, the tactile presentation device 1 includes a touch panel 2, a vibration unit 3, an integrated circuit 4, and a self-oscillating circuit 5.

[0020] The touch panel 2 includes a panel layer 11 formed of, for example, glass, and an electrostatic sensor 12 provided on the back side of the panel layer 11. The electrostatic sensor 12 is electrically connected to the integrated circuit 4 by a wiring member (not shown). The electrostatic sensor 12 detects a change in the electrostatic capacitance of the panel layer 11 in response to contact with the panel layer 11 by a finger P or the like, and outputs a signal indicating the detection result to the integrated circuit 4.

[0021] The vibration unit 3 is a part that includes a piezoelectric element 21 and vibrates at a predetermined resonance point. In this embodiment, the vibration unit 3 includes a vibration plate 22 and the piezoelectric element 21. The vibration plate 22 is a plate-like member made of, for example, a Ni-Fe alloy, Ni, brass, stainless steel, or the like. The touch panel 2 is fixed to one surface of the vibration unit 3, and the piezoelectric element 21 is fixed to the other surface of the vibration unit 3.

[0022] The vibration unit 3 has a resonance point in the tactile frequency band. The tactile frequency band is a frequency band in which vibration can be sensed as touch by, for example, a human fingertip, and is, for example, 100 Hz to 500 Hz. The resonance point of the vibration unit 3 can be designed depending on the material, shape, and size of the piezoelectric element 21 constituting the vibration unit 3, the thickness of the piezoelectric layer, the number of laminated piezoelectric layers, and the like.

[0023] In this embodiment, the diaphragm 22 and the panel layer 11 are fixed to the piezoelectric element 21. For this reason, the resonance point can be adjusted, for example, by adjusting the thickness of the diaphragm 22 and the thickness of the panel layer 11 in addition to the thickness of the piezoelectric element 21. By increasing the thickness of the diaphragm 22 and the thickness of the panel layer 11, the initial resonance point in the absence of contact with the vibration unit 3 (finger contact with the panel layer 11) can be shifted to a higher frequency side, and by increasing the thickness of the diaphragm 22 and the thickness of the panel layer 11, the initial resonance point in the absence of contact with the vibration unit 3 can be shifted to a lower frequency side.

[0024] In this embodiment, the vibration unit 3 is designed so that the initial resonance point when there is no contact with the vibration unit 3 is, for example, 100 Hz to 500 Hz, which is the tactile frequency band, and preferably 100 Hz to 200 Hz. Also, the vibration unit 3 is designed so that the fluctuating resonance point (the resonance point after fluctuating from the initial resonance point) of the vibration unit 3 when there is contact with the vibration unit 3 is 50 Hz to 250 Hz, and preferably 50 Hz to 200 Hz.

[0025] As shown in Fig. 2, the variable resonance point of the vibration unit 3 when there is contact with the vibration unit 3 fluctuates to the lower frequency side than the initial resonance point f0, and the amount of the fluctuation increases according to the magnitude of the pressure applied to the vibration unit 3. When the pressure is small, the variable resonance point f1 is smaller than the initial resonance point f0, and the vibration unit 3 presents a tactile sensation to the finger due to a weak vibration. When the pressure is large, the variable resonance point f2 is smaller than the variable resonance point f1, and the vibration unit 3 presents a tactile sensation to the finger due to a stronger vibration than when the pressure is small.

[0026] The piezoelectric element 21 has a rectangular parallelepiped shape that is flat in the thickness direction. The rectangular parallelepiped shape may include a shape in which the corners and ridges are chamfered, or a shape in which the corners and ridges are rounded. The piezoelectric element 21 has a piezoelectric body 23, a main electrode (driving electrode) 24, a ground electrode (driving electrode) 25, and a return electrode 26. Each of the main electrode 24, the ground electrode 25, and the return electrode 26 is formed by electrically connecting an internal electrode formed in a predetermined pattern inside the piezoelectric body 23 to an external electrode formed in a predetermined pattern on the outer surface of the piezoelectric body 23 via a through hole.

[0027] The piezoelectric element 23 is composed of a laminate of multiple piezoelectric layers. Each piezoelectric layer is made of a piezoelectric material such as a piezoelectric ceramic, and is laminated alternately with an internal electrode. Examples of the piezoelectric ceramic material include PZT [Pb(Zr,Ti)O3], PT(PbTiO3), PLZT [(Pb,La)(Zr,Ti)O3], and barium titanate (BaTiO3).

[0028] Each piezoelectric layer is formed, for example, by a sintered body of a ceramic green sheet containing the above-mentioned piezoelectric ceramic. In the actual piezoelectric element 23, each piezoelectric layer is integrated to such an extent that the boundaries between the piezoelectric layers cannot be recognized. The internal electrodes and external electrodes are formed of a conductive material. Examples of the conductive material include Ag, Pd, and Ag-Pd alloys. The internal electrodes and external electrodes are formed, for example, by a sintered body of a conductive paste containing the above-mentioned conductive material.

[0029] A wiring member (not shown) is used for electrically connecting the piezoelectric element 21 to an external device. For example, a flexible printed circuit board (FPC) is used as the wiring member. One end of the wiring member is electrically connected to each of the main electrode 24, the ground electrode 25, and the return electrode 26 of the piezoelectric element 21. For example, an anisotropic conductive adhesive can be used for connecting these electrodes to the wiring member. The other end of the wiring member is drawn out from the piezoelectric element 21 and electrically connected to the self-oscillation circuit 5.

[0030] The integrated circuit 4 is a circuit that generates a DC voltage (drive voltage) directed to the piezoelectric element 21. The integrated circuit 4 is electrically connected to the electrostatic sensor 12 and the self-excited oscillation circuit 5 by wiring members (not shown). Upon receiving a signal indicating the detection result of the change in the electrostatic capacitance of the panel layer 11 from the electrostatic sensor 12, the integrated circuit 4 generates a DC voltage and inputs it to the self-excited oscillation circuit 5.

[0031] The DC voltage input from the integrated circuit 4 to the self-excited oscillator circuit 5 may be constant regardless of the amount of change in the capacitance of the panel layer 11. In this case, by setting the DC voltage to a relatively small value, for example, about several volts, it becomes possible to construct the integrated circuit 4 at low cost.

[0032] Furthermore, the DC voltage input from the integrated circuit 4 to the self-excited oscillator circuit 5 may take multiple values. For example, the first 0.1 ms may be 3V, and the next 0.1 ms may be 5V. When the DC voltage takes multiple values, the periods during which each value is taken may be different. For example, the first 0.2 ms may be 3V, the next 0.1 ms may be 4V, and the next 0.5 ms may be 5V. In these cases, it becomes possible to vary the strength of the vibration in the vibration unit 3 in response to a certain touch, thereby increasing the variety of tactile sensations presented.

[0033] The self-oscillating circuit 5 is a circuit that causes the piezoelectric element 21 to self-oscillate in a frequency band based on the resonance point. As shown in FIG. 3, the self-oscillating circuit 5 includes resistors R1 and r2 and a transistor Tr, and is electrically connected to the main electrode 24, the ground electrode 25, and the feedback electrode 26 of the piezoelectric element 21, respectively, and the integrated circuit 4. The values ​​of the resistors R1 and R2 are appropriately designed depending on the configuration of the vibration unit 3, etc. In this embodiment, the resistor R1 is, for example, 100 kΩ, and the resistor R2 is, for example, 750 Ω. When a DC voltage from the integrated circuit 4 is applied between the + terminal and the - terminal, the piezoelectric element 21 is immediately charged. Then, a base current flows through the resistor R1 to the transistor Tr, and the transistor Tr is turned on.

[0034] When the transistor Tr is turned on, a discharge current begins to flow between the main electrode 24 and the ground electrode 25 of the piezoelectric element 21 through the resistor R2. This induces a positive voltage in the feedback electrode 26, and this voltage is applied to the base of the transistor Tr, so that the transistor Tr continues to be on. Thereafter, the discharge current between the main electrode 24 and the ground electrode 25 of the piezoelectric element 21 decreases, and when the voltage induced in the feedback electrode 26 falls below the base-emitter saturation voltage of the transistor Tr, the transistor Tr is turned off.

[0035] When the transistor Tr is turned off, a charging current begins to flow between the main electrode 24 and the ground electrode 25 of the piezoelectric element 21 through the resistor R2. This induces a negative voltage in the feedback electrode 26, further reducing the base voltage of the transistor Tr, so that the transistor Tr remains in the off state. Thereafter, the charging current between the main electrode 24 and the ground electrode 25 of the piezoelectric element 21 decreases, and when the voltage induced in the feedback electrode 26 exceeds the base-emitter saturation voltage of the transistor Tr, the transistor Tr turns on again. Thereafter, the above-mentioned charging and discharging operations are repeatedly performed in the piezoelectric element 21, causing the piezoelectric element 21 to continuously vibrate and oscillate in a frequency band based on the resonance point.

[0036] As described above, in the tactile presentation device 1 and the tactile presentation method, the vibration unit 3 including the piezoelectric element 21 has a resonance point in the tactile frequency band. The resonance point when the vibration unit 3 is touched shifts to a lower frequency band compared to the resonance point of the piezoelectric element 21 alone, so that the piezoelectric element 21, which self-oscillates upon receiving a drive voltage from the self-oscillating circuit 5, can generate vibrations in a frequency band where a tactile sensation is more easily obtained. Therefore, the tactile presentation device 1 and the tactile presentation method can present a tactile sensation of sufficient strength.

[0037] In this embodiment, the piezoelectric element 21 includes a piezoelectric body 23, driving electrodes (main electrode 24, ground electrode 25), and a feedback electrode 26. With this configuration, self-oscillation of the piezoelectric element 21 using the self-oscillation circuit 5 can be easily achieved.

[0038] In this embodiment, the vibration unit 3 is configured to include a vibration plate 22. In this case, the resonance point of the vibration unit 3 can be easily adjusted according to the design of the piezoelectric element 21 and the vibration plate 22. Therefore, the vibration unit 3 can generate vibrations in a frequency band that is more likely to produce a tactile sensation.

[0039] In this embodiment, the self-oscillating circuit 5 inputs a plurality of values ​​of drive voltage to the piezoelectric element 21. In this case, the variety of tactile sensations to be presented can be increased according to the value of the drive voltage.

[0040] In this embodiment, the initial resonance point f0 of the vibration unit 3 when there is no contact with the vibration unit 3 is 100 Hz to 500 Hz. This frequency band is a band in which the human body can easily sense tactile sensation as vibration. Therefore, by setting the initial resonance point of the vibration unit 3 within the above range, the vibration unit 3 can generate vibrations in a frequency band in which tactile sensation is more easily felt.

[0041] In this embodiment, the resonance points (variable resonance points f1, f2) of the vibration unit 3 when there is contact with the vibration unit 3 shift to the lower frequency side than the initial resonance point f0. By shifting the resonance points to the lower frequency side, it becomes possible to present a clearer tactile sensation.

[0042] In this embodiment, the amount of fluctuation in the resonance point of the vibration unit 3 when there is contact with the vibration unit 3 increases according to the magnitude of the pressure applied to the vibration unit 3. That is, in this embodiment, when the pressure is small, the fluctuation resonance point f1 is smaller than the initial resonance point f0, and when the pressure is large, the fluctuation resonance point f2 is smaller than the fluctuation resonance point f1. Therefore, it is possible to present various tactile sensations according to the state of contact with the vibration unit 3.

[0043] The gist of this disclosure is as follows: [1] to [8] [1] A tactile presentation device comprising: a vibration unit including a piezoelectric element and having a resonance point in a tactile frequency band; and a self-oscillation circuit electrically connected to the vibration unit, wherein the piezoelectric element self-oscillates in a frequency band based on the resonance point due to a driving voltage input from the self-oscillation circuit in response to contact with the vibration unit. [2] The tactile presentation device according to [1], wherein the piezoelectric element includes a piezoelectric body, a driving electrode, and a feedback electrode. [3] The tactile presentation device according to [1] or [2], wherein the vibration unit includes a vibration plate. [4] The tactile presentation device according to any one of [1] to [3], wherein the self-oscillating circuit inputs a plurality of values ​​of drive voltage to the piezoelectric element. [5] The tactile presentation device according to any one of [1] to [4], wherein an initial resonance point of the vibration unit when there is no contact with the vibration unit is 100 Hz to 500 Hz. [6] The tactile presentation device according to [5], wherein the resonance point of the vibration unit when there is contact with the vibration unit shifts to a lower frequency side than the initial resonance point. [7] The tactile presentation device according to [6], wherein the amount of fluctuation in the resonance point of the vibration unit when the vibration unit is in contact increases according to the magnitude of the pressure applied to the vibration unit. [8] A tactile presentation method using a vibration unit including a piezoelectric element and having a resonance point in a tactile frequency band, and a self-oscillating circuit electrically connected to the vibration unit, in which a driving voltage input from the self-oscillating circuit in response to contact with the vibration unit causes the piezoelectric element to self-oscillate in a frequency band based on the resonance point. [Explanation of symbols]

[0044] 1...tactile presentation device, 3...vibration unit, 5...self-oscillating circuit, 21...piezoelectric element, 22...diaphragm, 23...piezoelectric body, 24...main electrode (driving electrode), 25...ground electrode (driving electrode), 26...feedback electrode.

Claims

1. A vibration unit including a piezoelectric element and having a resonance point in a tactile frequency band; A self-oscillating circuit electrically connected to the vibration unit, The piezoelectric element self-oscillates in a frequency band based on the resonance point due to a drive voltage input from the self-oscillation circuit in response to contact with the vibration portion.

2. The tactile presentation device according to claim 1 , wherein the piezoelectric element includes a piezoelectric body, a driving electrode, and a feedback electrode.

3. The tactile presentation device according to claim 1 , wherein the vibration section includes a vibration plate.

4. The tactile presentation device according to claim 1 , wherein the self-oscillating circuit inputs a plurality of values ​​of drive voltage to the piezoelectric element.

5. 2. The tactile presentation device according to claim 1, wherein an initial resonance point of said vibration unit when there is no contact with said vibration unit is between 100 Hz and 500 Hz.

6. The tactile presentation device according to claim 5 , wherein a resonance point of the vibration unit when the vibration unit is touched shifts to a lower frequency side than the initial resonance point.

7. The tactile presentation device according to claim 6 , wherein a variation in the resonance point of the vibration unit when the vibration unit is touched increases according to a magnitude of a pressure applied to the vibration unit.

8. A vibration unit including a piezoelectric element and having a resonance point in a tactile frequency band; a self-oscillating circuit electrically connected to the vibration unit, A tactile presentation method, comprising: causing the piezoelectric element to self-oscillate in a frequency band based on the resonance point by a driving voltage input from the self-oscillation circuit in response to contact with the vibration portion.

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