JP2021057299A - Driving method and driving circuit for piezoelectric switch - Google Patents

Abstract

To provide a driving method and driving circuit for a piezoelectric switch, with which it is possible to accurately identify an operation area operated.SOLUTION: A driving method for a piezoelectric switch including a plurality of piezoelectric elements, which are attached to an inner surface of an enclosure so as to be spaced apart from one another and causes each corresponding part at an outer surface of the enclosure to function as an operation area, comprises: a step S11 for measuring each of voltages occurring at the plurality of piezoelectric elements; a step S12 for, on the basis of values of the voltages measured in the step S11 for measuring, from among the plurality of piezoelectric elements, identifying a first piezoelectric element having the highest voltage value and a second piezoelectric element having the highest voltage value next to the first piezoelectric element; and a step S13 for, on the basis of a difference between the voltage value of the first piezoelectric element and the voltage value of the second piezoelectric element identified in the step S12 for identifying, determining presence or absence of an operation with respect to an operation area corresponding to the first piezoelectric element.SELECTED DRAWING: Figure 6

Description

One aspect of the present invention relates to a driving method and a driving circuit of a piezoelectric switch.

Patent Document 1 describes a piezoelectric switch using a piezoelectric element that generates an electric signal by bending it by applying a mechanical force. Since this piezoelectric switch is a non-contact type, there are no problems such as poor contact contact and poor operation during freezing.

Jikkai Sho 58-79823

A piezoelectric switch having a plurality of piezoelectric elements attached to the inner surface of the housing and having a portion corresponding to each piezoelectric element on the outer surface of the housing functioning as an operation area can be considered. In such a piezoelectric switch, it is required to accurately specify the operated operating area.

One aspect of the present invention provides a drive method and drive circuit for a piezoelectric switch that can accurately identify the manipulated operating region.

The method for driving a piezoelectric switch according to one aspect of the present invention is a piezoelectric switch including a plurality of piezoelectric elements that are attached to the inner surface of the housing apart from each other and each of the corresponding portions on the outer surface of the housing functions as an operation region. Based on the process of measuring the voltage generated in each of the plurality of piezoelectric elements and the voltage value measured in the measuring process, the first piezoelectric element having the highest voltage value among the plurality of piezoelectric elements is used. The step of specifying the element and the second piezoelectric element having the next highest voltage value after the first piezoelectric element, and the voltage value of the first piezoelectric element and the voltage value of the second piezoelectric element specified in the specifying step. A step of determining whether or not there is an operation on the operation region corresponding to the first piezoelectric element based on the difference is included.

In the above one aspect, the plurality of piezoelectric elements are attached to the inner surface of the housing so as to be separated from each other, and the corresponding portions on the outer surface of the housing function as operating regions. When the operation area is operated, the displacement amount of the piezoelectric element corresponding to the operated operation area becomes the largest. Therefore, in order to specify the operation region, the voltage generated in each of the plurality of piezoelectric elements is measured, and the first piezoelectric element having the highest voltage value is specified based on the measured voltage value. Thereby, the operated operation area can be specified. Further, the second piezoelectric element having the next highest voltage value after the first piezoelectric element is identified, and the presence or absence of an operation on the operation region is determined based on the difference between the voltage value of the first piezoelectric element and the voltage value of the second piezoelectric element. To do. As a result, noise on the voltage value and the influence of erroneous operation can be suppressed. As a result, the manipulated operating area can be accurately identified.

In the determination step, if the absolute value of the difference is equal to or greater than a preset first threshold value, it may be determined that there is an operation. In this case, it is possible to easily determine whether or not there is an operation on the operation area.

The method for driving a piezoelectric switch according to one aspect of the present invention is a piezoelectric switch including a plurality of piezoelectric elements that are attached to the inner surface of the housing apart from each other and each of the corresponding portions on the outer surface of the housing functions as an operation region. Based on the process of measuring the voltage generated in each of the plurality of piezoelectric elements and the voltage value measured in the measuring process, the first piezoelectric element having the highest voltage value among the plurality of piezoelectric elements is used. The ratio of the voltage value of the second piezoelectric element to the voltage value of the first piezoelectric element specified in the step of specifying the element and the second piezoelectric element having the next highest voltage value after the first piezoelectric element. Based on the above, the step of determining whether or not there is an operation on the operation region corresponding to the first piezoelectric element is included.

In the above one aspect, the plurality of piezoelectric elements are attached to the inner surface of the housing so as to be separated from each other, and the corresponding portions on the outer surface of the housing function as operating regions. When the operation area is operated, the displacement amount of the piezoelectric element corresponding to the operated operation area becomes the largest. Therefore, in order to specify the operation region, the voltage generated in each of the plurality of piezoelectric elements is measured, and the first piezoelectric element having the highest voltage value is specified based on the measured voltage value. Thereby, the operated operation area can be specified. Further, the second piezoelectric element having the next highest voltage value after the first piezoelectric element is specified, and the presence or absence of an operation on the operation region is determined based on the ratio of the voltage value of the second piezoelectric element to the voltage value of the first piezoelectric element. .. As a result, noise on the voltage value and the influence of erroneous operation can be suppressed. As a result, the manipulated operating area can be accurately identified.

In the step of determining, if the absolute value of the ratio is equal to or less than a preset first threshold value, it may be determined that there is an operation. In this case, it is possible to easily determine whether or not there is an operation on the operation area.

In the specifying step, the first piezoelectric element and the second piezoelectric element may be specified when any of the voltage values measured in the measuring step is equal to or higher than a preset second threshold value. In this case, since the first piezoelectric element and the second piezoelectric element are specified only when there is a high possibility that the operation region has been operated, the piezoelectric switch can be efficiently driven.

The drive circuit of the piezoelectric switch according to one aspect of the present invention is a piezoelectric switch including a plurality of piezoelectric elements that are attached to the inner surface of the housing apart from each other and each of the corresponding portions on the outer surface of the housing functions as an operation region. The first piezoelectric, which has the highest voltage value among the plurality of piezoelectric elements, is based on the measuring unit that measures the voltage generated in each of the plurality of piezoelectric elements and the voltage value measured by the measuring unit. The element and the second piezoelectric element having the next highest voltage value after the first piezoelectric element are specified, and the first piezoelectric element is based on the difference between the voltage value of the first piezoelectric element and the voltage value of the second piezoelectric element. It is provided with a control unit for determining whether or not there is an operation on the operation area corresponding to.

In the above one aspect, the plurality of piezoelectric elements are attached to the inner surface of the housing so as to be separated from each other, and the corresponding portions on the outer surface of the housing function as operating regions. When the operation area is operated, the displacement amount of the piezoelectric element corresponding to the operated operation area becomes the largest. Therefore, in order to specify the operation region, the voltage generated in each of the plurality of piezoelectric elements is measured, and the first piezoelectric element having the highest voltage value is specified based on the measured voltage value. Thereby, the operated operation area can be specified. Further, the second piezoelectric element having the next highest voltage value after the first piezoelectric element is identified, and the presence or absence of an operation on the operation region is determined based on the difference between the voltage value of the first piezoelectric element and the voltage value of the second piezoelectric element. To do. As a result, noise on the voltage value and the influence of erroneous operation can be suppressed. As a result, the manipulated operating area can be accurately identified.

The drive circuit of the piezoelectric switch according to one aspect of the present invention is a piezoelectric switch including a plurality of piezoelectric elements that are attached to the inner surface of the housing apart from each other and each of the corresponding portions on the outer surface of the housing functions as an operation region. The first piezoelectric, which has the highest voltage value among the plurality of piezoelectric elements, is based on the measuring unit that measures the voltage generated in each of the plurality of piezoelectric elements and the voltage value measured by the measuring unit. The element and the second piezoelectric element having the next highest voltage value after the first piezoelectric element are specified, and the first piezoelectric element is set based on the ratio of the voltage value of the second piezoelectric element to the voltage value of the first piezoelectric element. A control unit for determining the presence or absence of an operation on the corresponding operation area is provided.

In the above one aspect, the plurality of piezoelectric elements are attached to the inner surface of the housing so as to be separated from each other, and the corresponding portions on the outer surface of the housing function as operating regions. When the operation area is operated, the displacement amount of the piezoelectric element corresponding to the operated operation area becomes the largest. Therefore, in order to specify the operation region, the voltage generated in each of the plurality of piezoelectric elements is measured, and the first piezoelectric element having the highest voltage value is specified based on the measured voltage value. Thereby, the operated operation area can be specified. Further, the second piezoelectric element having the next highest voltage value after the first piezoelectric element is specified, and the presence or absence of an operation on the operation region is determined based on the ratio of the voltage value of the second piezoelectric element to the voltage value of the first piezoelectric element. .. As a result, noise on the voltage value and the influence of erroneous operation can be suppressed. As a result, the manipulated operating area can be accurately identified.

According to one aspect of the present invention, there is provided a driving method and a driving circuit of a piezoelectric switch capable of accurately specifying an operated operating area.

FIG. 1 is a perspective view of the piezoelectric switch according to the embodiment. FIG. 2 is a cross-sectional view taken along the line II-II of FIG. FIG. 3 is a perspective view of the conductor layer of the wiring member as viewed from the base side. FIG. 4 is a cross-sectional view taken along the IV-IV line of FIG. FIG. 5 is a block diagram showing a configuration of an electronic device including the piezoelectric switch and the drive circuit according to the embodiment. FIG. 6 is a flowchart showing a driving method of the piezoelectric switch according to the first example. FIG. 7A is a cross-sectional view when the operation area R1 is operated. FIG. 7B is a graph showing the voltage amplitudes of the piezoelectric elements P1 and P2 when the operation region R1 is operated. FIG. 8A is a cross-sectional view when the operation area R2 is operated. FIG. 8B is a graph showing the voltage amplitudes of the piezoelectric elements P1 and P2 when the operation region R2 is operated. FIG. 9 is a flowchart showing a driving method of the piezoelectric switch according to the second example. FIG. 10A is a cross-sectional view showing a vibration state of the piezoelectric elements P1 and P2 when there is no operation. FIG. 10B is a cross-sectional view showing a vibration state of the piezoelectric elements P1 and P2 when there is an operation. FIG. 10C is a graph showing the difference in voltage amplitude in the piezoelectric element P2. FIG. 11 is a flowchart showing a driving method of the piezoelectric switch according to the third example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals will be used for the same elements or elements having the same function, and duplicate description will be omitted.

FIG. 1 is a perspective view of the piezoelectric switch according to the embodiment. FIG. 2 is a cross-sectional view taken along the line II-II of FIG. As shown in FIGS. 1 and 2, the piezoelectric switch 1 includes a plurality of piezoelectric elements P1 and P2, and a wiring member 2 in which the plurality of piezoelectric elements P1 and P2 are arranged apart from each other. The piezoelectric switch 1 is used by being attached to the housing 3 of an electronic device 50 (see FIG. 5) such as a smartphone, a tablet, or a smart watch. Note that the housing 3 is not shown in FIG.

The plurality of piezoelectric elements P1 and P2 are attached to the inner surface 3a of the housing 3 so as to be separated from each other. The plurality of piezoelectric elements P1 and P2 are attached to the inner surface 3a so as to be displaced together with the housing 3 by pressing the outer surface 3b of the housing 3. The plurality of piezoelectric elements P1 and P2 are bonded (adhered) to the inner surface 3a by, for example, an adhesive layer (not shown).

On the outer surface 3b of the housing 3, for example, operation regions R1 and R2 that can be operated (pressed) by an operator with a finger are set corresponding to the piezoelectric elements P1 and P2. In other words, the piezoelectric elements P1 and P2 make the corresponding portions on the outer surface 3b of the housing 3 function as operation areas R1 and R2, respectively. The piezoelectric switch 1 is a sensing device that detects an operation.

The operation areas R1 and R2 are set so as to overlap the piezoelectric elements P1 and P2 when viewed from a direction orthogonal to the outer surface 3b, for example. The operation areas R1 and R2 may be colored, for example. This makes it easier for the operator to visually recognize the operation areas R1 and R2. The outer surfaces 3b of the operation areas R1 and R2 may be formed so as to project in a convex shape. This makes it easier for the operator to visually and tactilely recognize the operation areas R1 and R2. For example, the operation areas R1 and R2 function as virtual switches for the operator. The operation areas R1 and R2 function as volume control switches as an example.

The piezoelectric switch 1 does not distinguish the operation areas R1 and R2 as different operation areas depending on the drive method and the drive circuit, and between the operation areas R1 and R2 and the operation area R1 and the operation area R2 on the outer surface 3b. The area arranged in is also functioned as one integrated operation area R3. When the operation area R3 is used as a virtual switch, the operation area R3 may be colored, or the outer surface 3b of the operation area R3 may be formed so as to project convexly. The operation region R3 includes operation regions R1 and R2 that completely overlap the piezoelectric elements P1 and P2 when viewed from a direction orthogonal to the outer surface 3b, and portions located between the operation regions R1 and R2 on the outer surface 3b. You may.

The piezoelectric elements P1 and P2 have the same configuration as each other. The piezoelectric elements P1 and P2 have, for example, a rectangular plate shape. The piezoelectric elements P1 and P2 have, for example, the same shape as each other. The piezoelectric elements P1 and P2 have main surfaces Pa and Pb facing each other in the thickness direction (Z direction), respectively. The main surface Pa is connected to the wiring member 2. The main surface Pa includes an outer surface of the first electrode 11 and an outer surface of the electrode portion 13 of the second electrode 12, which will be described later. The main surface Pb includes the outer surface of the electrode portion 14 of the second electrode 12, which will be described later. The main surface Pb is attached to the inner surface 3a. The main surface Pb is entirely bonded (adhered) to the inner surface 3a by, for example, an adhesive layer (not shown).

The piezoelectric elements P1 and P2 have a piezoelectric body 10, a first electrode 11, and a second electrode 12, respectively. The piezoelectric body 10 is made of a piezoelectric material. In this embodiment, the piezoelectric body 10 is made of a piezoelectric ceramic material. The piezoelectric ceramic material is, for example, PZT [Pb (Zr, Ti) O ₃ ], PT (PbTIO ₃ ), PLZT [(Pb, La) (Zr, Ti) O ₃ ], or barium titanate (BaTIO ₃ ). Is. The piezoelectric body 10 is composed of, for example, a sintered body of a ceramic green sheet containing the above-mentioned piezoelectric ceramic material.

The piezoelectric body 10 has, for example, a rectangular plate shape. The piezoelectric body 10 has a pair of main surfaces 10a and 10b facing each other and a pair of end faces 10c and 10d facing each other. The pair of main surfaces 10a and 10b have, for example, the same shape as each other. The pair of main surfaces 10a and 10b have, for example, a rectangular shape. The pair of end faces 10c and 10d have, for example, the same shape as each other. The pair of end faces 10c and 10d have, for example, a rectangular shape. The pair of end faces 10c and 10d extend in the opposite direction of the pair of main faces 10a and 10b so as to connect the pair of main faces 10a and 10b to each other. The pair of end faces 10c and 10d face each other in the long side direction of the pair of main faces 10a and 10b. The pair of end faces 10c and 10d extend in the short side direction of the pair of main faces 10a and 10b.

In the following, the long side direction of the pair of main surfaces 10a and 10b is the X direction, the short side direction of the pair of main surfaces 10a and 10b is the Y direction, and the opposite direction of the pair of main surfaces 10a and 10b is the Z direction. The X direction coincides with the direction in which the piezoelectric elements P1 and P2 are separated from each other. The Z direction is a direction orthogonal to the pair of main surfaces 10a and 10b. The length of the piezoelectric body 10 (length in the X direction) is, for example, 5.4 mm. The width (length in the Y direction) of the piezoelectric body 10 is, for example, 1.5 mm. The thickness of the piezoelectric body 10 (length in the Z direction) is, for example, 0.3 mm.

The first electrode 11 and the second electrode 12 are conductors containing a conductive material (for example, Ag, Pd, Cu, etc.). These conductors are configured as a sintered body of a conductive paste containing a conductive material. Voltages having different polarities are applied to the first electrode 11 and the second electrode 12.

The first electrode 11 is in contact with the main surface 10a. The first electrode 11 has a rectangular shape when viewed from the Z direction. The length of the first electrode 11 in the X direction is, for example, 4.4 mm. The width of the first electrode 11 (length in the Y direction) is equivalent to the width of the main surface 10a (length in the Y direction). The first electrode 11 covers the entire main surface 10a in the Y direction.

The second electrode 12 has an electrode portion 13, an electrode portion 14, and an electrode portion 15. The electrode portion 13 is arranged on the main surface 10a. The electrode portion 13 is in contact with the main surface 10a. The electrode portion 13 has a rectangular shape when viewed from the Z direction. The length of the electrode portion 13 in the X direction is, for example, 0.5 mm. The width of the electrode portion 13 (length in the Y direction) is equivalent to the width of the main surface 10a (length in the Y direction). The electrode portion 13 covers the entire main surface 10a in the Y direction.

The electrode portion 14 is arranged on the main surface 10b. The electrode portion 14 is in contact with the main surface 10b. The electrode portion 14 has the same shape as the main surface 10b when viewed from the Z direction. The electrode portion 14 covers the entire main surface 10b. The electrode portion 15 is arranged on the end face 10c. The electrode portion 15 is in contact with the end face 10c. The electrode portion 15 has the same shape as the end face 10c when viewed from the X direction. The electrode portion 15 covers the entire end face 10c.

The electrode portion 13 and the electrode portion 15 are connected to each other at a ridge line portion between the main surface 10a and the end surface 10c. The electrode portion 14 and the electrode portion 15 are connected to each other at a ridgeline portion between the main surface 10b and the end surface 10c. The electrode portion 13 and the electrode portion 14 are connected to each other by the electrode portion 15. The electrode portion 13, the electrode portion 14, and the electrode portion 15 are integrally formed with each other and are continuous. The electrode portion 13, the electrode portion 14, and the electrode portion 15 are electrically connected to each other.

The first electrode 11 and the electrode portion 13 are separated from each other on the main surface 10a. The first electrode 11 is arranged on the end surface 10d side of the main surface 10a, and the electrode portion 13 is arranged on the end surface 10c side of the main surface 10a. The area where the first electrode 11 is in contact with the main surface 10a is larger than the area where the electrode portion 13 is in contact with the main surface 10a.

The first electrode 11 and the electrode portion 14 face each other via the piezoelectric body 10. When viewed from the Z direction, the electrode portion 14 has a region overlapping with the first electrode 11. When voltages having different polarities are applied to the first electrode 11 and the second electrode 12, an electric field is generated between the first electrode 11 and the electrode portion 14. As a result, in the piezoelectric body 10, the region sandwiched between the first electrode 11 and the electrode portion 14 becomes the piezoelectrically active active region Ra, and the active region Ra is displaced.

In the piezoelectric body 10, the region on the end face 10d side is the active region Ra, and the region on the end face 10c side is the inactive region. The piezoelectric elements P1 and P2 are arranged so that the end face 10c of the piezoelectric element P1 and the end face 10d of the piezoelectric element P2 face each other. That is, the inert region of the piezoelectric element P1 is arranged closer to the piezoelectric element P2 (on the piezoelectric element P2 side). The active region Ra of the piezoelectric element P2 is arranged closer to the piezoelectric element P1 (on the piezoelectric element P1 side).

The wiring member 2 is, for example, a flexible printed circuit board (FPC) or a flexible flat cable (FFC). The wiring member 2 is a strip-shaped member having flexibility. The wiring member 2 has a T-shape in a plan view (when placed on a flat surface without bending and viewed from the thickness direction).

The wiring member 2 has a first wiring portion 21 in which the piezoelectric elements P1 and P2 are arranged, and a second wiring portion 22 connected to the first wiring portion 21. The first wiring portion 21 is a strip-shaped member in which the piezoelectric elements P1 and P2 extend in a direction (X direction) away from each other. The length (length in the X direction) of the first wiring portion 21 is, for example, 25 mm. The width (length in the Y direction) of the first wiring portion 21 is, for example, 2 mm. The thickness (length in the Z direction) of the first wiring portion 21 is, for example, 125 μm.

The piezoelectric element P1 is arranged on one end 21a side of the first wiring portion 21 in the X direction, and the piezoelectric element P2 is arranged on the other end 21b side. The separation distance between one end 21a and the piezoelectric element P1 in the X direction is, for example, equivalent to the separation distance between the other end 21b and the piezoelectric element P2 in the X direction, and is, for example, 1.5 mm. The arrangement interval L2 of the piezoelectric elements P1 and P2 is longer than the length L1 of the piezoelectric elements P1 and P2 in the direction (X direction) in which the piezoelectric elements P1 and P2 are separated from each other.

The second wiring portion 22 is a strip-shaped member extending in a direction intersecting with the first wiring portion 21. The second wiring portion 22 extends in the Y direction. One end 22a of the second wiring portion 22 is connected to the first wiring portion 21 between the piezoelectric element P1 and the piezoelectric element P2. One end 22a is connected to the first wiring portion 21 at an intermediate position between the piezoelectric element P1 and the piezoelectric element P2. The length of the second wiring portion 22 (length in the Y direction) is, for example, 39 mm. The width (length in the X direction) of the second wiring portion 22 is, for example, 4.6 mm.

FIG. 3 is a perspective view of the conductor layer of the wiring member as viewed from the base side. FIG. 4 is a cross-sectional view taken along the IV-IV line of FIG. As shown in FIGS. 2 to 4, the wiring member 2 includes a base 30, a plurality of conductor layers 31, 32, 33, 34, 35, 36, 37, 38 (hereinafter, conductor layers 31 to 38), and the like. It has an adhesive layer 39, a cover 40, a plurality of connecting conductors 41, a reinforcing member 4, and a plurality of connecting electrodes 5, 6, 7, and 8. In FIG. 3, the reinforcing member 4 is not shown. A plurality of connection electrodes 5, 6, 7, and 8 are indicated by broken lines. Each conductor layer 31-38 passes through the base 30 and is shown by a solid line.

The base 30 has a band shape and has a pair of main surfaces 30a and 30b facing each other. The base 30 has electrical insulation. The base 30 is a resin layer made of a resin such as a polyimide resin, for example. The thickness of the base 30 is, for example, 25 μm.

The conductor layers 31 to 38 are joined (adhered) to the main surface 30a of the base 30 by an adhesive layer (not shown). The conductor layers 31 to 38 are arranged on the main surface 30a so as to be separated from each other. Each of the conductor layers 31 to 38 extends from the other end 22b of the second wiring portion 22 in the Y direction and reaches the central portion of the first wiring portion 21 in the X direction. Each of the conductor layers 31, 32, 33, 34 is bent 90 degrees at the central portion of the first wiring portion 21 in the X direction and extends in the X direction to reach one end 21a. Each of the conductor layers 35, 36, 37, 38 is bent 90 degrees at the central portion of the first wiring portion 21 in the X direction and extends in the X direction to reach the other end 21b.

That is, each of the conductor layers 31, 32, 33, 34 is a portion extending in the Y direction in the second wiring portion 22 and a portion bent by 90 degrees in the central portion in the X direction of the first wiring portion 21. And a portion extending in the X direction at one end 21a side of the first wiring portion 21 are connected to each other. Each conductor layer 35, 36, 37, 38 has a portion extending in the Y direction in the second wiring portion 22 and a portion bent by 90 degrees in the central portion in the X direction of the first wiring portion 21. A portion extending in the X direction on the other end 21b side of the first wiring portion 21 is connected to each other.

Each conductor layer 31-38 contains, for example, Cu. Each conductor layer 31 to 38 has, for example, an electrolytic Cu foil formed by electrolytic plating and a Cu plating layer formed by electroless plating on the electrolytic Cu foil. The conductor layers 31 to 38 are exposed from the adhesive layer 39 and the cover 40 on the other end 22b side of the second wiring portion 22 in the Y direction. The exposed portions of the conductor layers 31 to 38 are further provided with a Ni plating layer and an Au plating layer in this order by, for example, electroless plating. The width of each conductor layer 31 to 38 is, for example, 200 μm. The thickness of the electrolytic Cu foil is, for example, 9 μm. The thickness of the Cu plating layer is, for example, 9 μm or more and 14 μm or less. The thickness of the Ni plating layer is, for example, 3 μm or more and 8 μm or less. The thickness of the Au plating layer is, for example, 0.03 μm or more.

The adhesive layer 39 is arranged on the main surface 30a so as to cover the conductor layers 31 to 38 and fill the space between the conductor layers 31 to 38. The adhesive layer 39 is a resin layer made of a resin such as an epoxy resin, for example. The thickness of the adhesive layer 39 is, for example, 25 μm.

The cover 40 is arranged on the main surface 30a. The cover 40 is bonded (adhered) to each of the conductor layers 31 to 38 and a region of the main surface 30a exposed from each of the conductor layers 31 to 38 by an adhesive layer 39. The cover 40 is a resin layer made of a resin such as a polyimide resin, for example. The thickness of the cover 40 is, for example, 12.5 μm.

The adhesive layer 39 and the cover 40 are not arranged on the main surface 30a on the other end 22b side of the second wiring portion 22 in the Y direction. The adhesive layer 39 and the cover 40 and the other end 22b are separated from each other in the Y direction. The separation distance between the adhesive layer 39 and the cover 40 and the other end 22b in the Y direction is, for example, 5 mm. On the other end 22b side of the second wiring portion 22 in the Y direction, one end of each conductor layer 31 to 38 is exposed as described above. For example, a connector may be connected to one end of each of the conductor layers 31 to 38.

The plurality of connecting conductors 41 are arranged in the through holes provided in the base 30. The plurality of connecting conductors 41 are arranged on the other end of each of the conductor layers 31 to 38. The plurality of connecting conductors 41 include, for example, Cu.

Each of the connecting conductors 41 arranged on the other ends of the conductor layers 31 and 33 is arranged at a position overlapping the connecting electrode 5 when viewed from the Z direction, and electrically connects the conductor layers 31 and 33 and the connecting electrode 5. You are connected. Each connecting conductor 41 arranged on the other end of the conductor layers 32 and 34 is arranged at a position overlapping the connecting electrode 6 when viewed from the Z direction, and electrically connects the conductor layers 32 and 34 and the connecting electrode 6. You are connected. Each of the connecting conductors 41 arranged on the other ends of the conductor layers 35 and 37 is arranged at a position overlapping with the connecting electrode 7 when viewed from the Z direction, and electrically connects the conductor layers 35 and 37 and the connecting electrode 7. You are connected. Each of the connecting conductors 41 arranged on the other ends of the conductor layers 36 and 38 is arranged at a position overlapping the connecting electrode 8 when viewed from the Z direction, and electrically connects the conductor layers 35 and 37 and the connecting electrode 8. You are connected.

The reinforcing member 4 is a plate-shaped member arranged on the main surface 30b of the base 30. The reinforcing member 4 is provided so as to overlap one end of each of the conductor layers 31 to 38 exposed from the adhesive layer 39 and the cover 40 when viewed from the Z direction. The reinforcing member 4 is joined (adhered) to the main surface 30b by, for example, a thermohard adhesive (not shown). The thickness of the thermohard adhesive is, for example, 40 μm. The reinforcing member 4 is provided on the other end 22b side of the second wiring portion 22 in the Y direction and covers the entire second wiring portion 22 in the X direction. The reinforcing member 4 has, for example, a rectangular plate shape, and the width of the reinforcing member 4 (length in the X direction) is equivalent to the width of the second wiring portion 22 (length in the X direction). The length of the reinforcing member 4 in the Y direction is, for example, 8 mm. The thickness of the reinforcing member 4 is, for example, 225 μm. The reinforcing member 4 is made of, for example, a resin such as a polyimide resin.

The connection electrodes 5, 6, 7, and 8 are arranged on the main surface 30b of the base 30. The connection electrodes 5, 6, 7, 8 and the base 30 are directly bonded to each other. The connection electrodes 5, 6, 7, and 8 are arranged in the first wiring portion 21.

The connection electrode 5 is arranged at a position overlapping the first electrode 11 of the piezoelectric element P1 when viewed from the Z direction, and is connected to the first electrode 11. The connection electrode 6 is arranged at a position overlapping the electrode portion 13 of the second electrode 12 of the piezoelectric element P1 when viewed from the Z direction, and is connected to the electrode portion 13. The connection electrode 7 is arranged at a position overlapping the first electrode 11 of the piezoelectric element P2 when viewed from the Z direction, and is connected to the first electrode 11. The connection electrode 8 is arranged at a position overlapping the electrode portion 13 of the second electrode 12 of the piezoelectric element P2 when viewed from the Z direction, and is connected to the electrode portion 13. The connection electrodes 5, 6, 7, and 8 are connected to the electrode portions 13 of the first electrode 11 and the second electrode 12 by, for example, a conductive adhesive. The conductive adhesive may be formed of, for example, a heat-meltable metal such as solder, or may be formed of a conductive paste containing Au, Cu or the like as the conductive material.

The connection electrodes 5 and 7 have the same shape as the first electrodes 11 of the piezoelectric elements P1 and P2 when viewed from the Z direction, for example. The connection electrodes 6 and 8 have the same shape as the electrode portion 13 of the second electrode 12 of the piezoelectric elements P1 and P2 when viewed from the Z direction, for example.

Subsequently, the drive circuit 100 of the piezoelectric switch 1 will be described. FIG. 5 is a block diagram showing a configuration of an electronic device including the piezoelectric switch and the drive circuit according to the embodiment. As shown in FIG. 5, the electronic device 50 includes an electronic device main body 51, a piezoelectric switch 1, and a drive circuit 100. The drive circuit 100 is electrically connected to each of the piezoelectric switch 1 and the electronic device main body 51. The drive circuit 100 includes a measurement unit 101, a measurement unit 102, a drive unit 103, and a control unit 104.

The measuring unit 101 is a voltmeter that measures the voltage generated in the piezoelectric element P1 and the piezoelectric element P2, respectively. The measuring unit 101 transmits the measured voltage values of the piezoelectric element P1 and the piezoelectric element P2 to the control unit 104, respectively. The measuring unit 101 is, for example, an AD converter.

The measuring unit 101 is connected to, for example, the conductor layers 31, 32, 35, 36 (see FIG. 3) of the wiring member 2. The conductor layer 31 is electrically connected to the first electrode 11 (see FIG. 2) of the piezoelectric element P1 via the connecting conductor 41 and the connecting electrode 5 (see FIG. 3). The conductor layer 32 is electrically connected to the second electrode 12 (see FIG. 2) of the piezoelectric element P1 via the connecting conductor 41 and the connecting electrode 6 (see FIG. 3). The conductor layer 35 is electrically connected to the first electrode 11 of the piezoelectric element P2 via the connecting conductor 41 and the connecting electrode 7 (see FIG. 3). The conductor layer 36 is electrically connected to the second electrode 12 of the piezoelectric element P2 via the connecting conductor 41 and the connecting electrode 8 (see FIG. 3).

The measuring unit 101 measures the voltage generated in the piezoelectric element P1 by measuring the voltage between the conductor layers 31 and 32, and measures the voltage generated in the piezoelectric element P2 by measuring the voltage between the conductor layers 35 and 36. Measure the voltage. The measuring unit 101 is connected to the conductor layer 33 instead of the conductor layer 31, the conductor layer 34 instead of the conductor layer 32, the conductor layer 37 instead of the conductor layer 35, or the conductor layer 38 instead of the conductor layer 36. You may. Even in this case, the measuring unit 101 can measure the voltage generated in the piezoelectric elements P1 and P2.

The measuring unit 102 is a voltmeter that measures the voltage generated in the piezoelectric element P2. The measuring unit 102 transmits the measured voltage value of the piezoelectric element P2 to the control unit 104. The measuring unit 102 is, for example, an AD converter. The measuring unit 102 is connected to, for example, the conductor layers 37 and 38 (see FIG. 3) of the wiring member 2. The conductor layer 37 is electrically connected to the first electrode 11 (see FIG. 2) of the piezoelectric element P2 via the connecting conductor 41 and the connecting electrode 7 (see FIG. 3). The conductor layer 38 is electrically connected to the second electrode 12 (see FIG. 2) of the piezoelectric element P2 via the connecting conductor 41 and the connecting electrode 8 (see FIG. 3).

The measuring unit 102 measures the voltage generated in the piezoelectric element P2 by measuring the voltage between the conductor layers 37 and 38. The measuring unit 102 may be connected to the conductor layer 35 instead of the conductor layer 37, or to the conductor layer 36 instead of the conductor layer 38. Even in this case, the measuring unit 102 can measure the voltage generated in the piezoelectric element P2.

The drive unit 103 applies a drive signal (drive voltage) to the piezoelectric element P1 to vibrate the piezoelectric element P1. The drive unit 103 is configured to, for example, give a drive signal to the piezoelectric element P1 for a predetermined time when receiving a signal from the control unit 104. The drive signal is, for example, a sinusoidal signal. The drive unit 103 is, for example, a function generator.

The drive unit 103 is connected to, for example, the conductor layers 33 and 34 (see FIG. 3) of the piezoelectric element P1. The conductor layer 33 is electrically connected to the first electrode 11 (see FIG. 2) of the piezoelectric element P1 via the connecting conductor 41 and the connecting electrode 5 (see FIG. 3). The conductor layer 34 is electrically connected to the second electrode 12 (see FIG. 2) of the piezoelectric element P1 via the connecting conductor 41 and the connecting electrode 6 (see FIG. 3). The drive unit 103 vibrates the piezoelectric element P1 by inputting a drive signal between the conductor layers 33 and 34. The drive unit 103 may be connected to the conductor layer 31 instead of the conductor layer 33, or to the conductor layer 32 instead of the conductor layer 34. Even in this case, the drive unit 103 can vibrate the piezoelectric element P1.

The control unit 104 includes, for example, a CPU (Central Processing Unit) and controls the drive circuit 100 in an integrated manner. The control unit 104 may further include a ROM (Read Only Memory) and a RAM (Random Access Memory). The control unit 104 performs various processes by loading the program stored in the ROM into the RAM and executing the program in the CPU, for example. The operation of the control unit 104 will be described later. The control unit 104 may also serve as a control unit for the electronic device main body 51.

Subsequently, a method of driving the piezoelectric switch 1 will be described.

[First example]
FIG. 6 is a flowchart showing a driving method of the piezoelectric switch according to the first example. As shown in FIG. 6, the driving method of the piezoelectric switch 1 according to the first example includes steps S11 to S13. In this example, it is determined whether or not there is an operation on the operation areas R1 and R2. In step S11, the measuring unit 101 measures the voltages generated in the plurality of piezoelectric elements P1 and P2, respectively. The measuring unit 101 transmits the voltage values of the piezoelectric elements P1 and P2 to the control unit 104.

The voltage generated in the piezoelectric element will be described with reference to FIGS. 7 and 8. FIG. 7A is a cross-sectional view when the operation area R1 is operated. FIG. 7B is a graph showing the voltage amplitudes of the piezoelectric elements P1 and P2 when the operation region R1 is operated. FIG. 8A is a cross-sectional view when the operation area R2 is operated. FIG. 8B is a graph showing the voltage amplitudes of the piezoelectric elements P1 and P2 when the operation region R2 is operated. As shown in FIGS. 7 (a) and 8 (a), in this example, the outer surfaces 3b of the operation regions R1 and R2 correspond to the piezoelectric elements P1 and P2, respectively, and are formed so as to project in a convex shape. .. The vertical axis of FIGS. 7 (b) and 8 (b) shows the voltage amplitude, and the horizontal axis shows the time.

As shown in FIGS. 7 (a) and 8 (a), when the outer surface 3b of the housing 3 is operated (pressed) by the operator's finger, the housing 3 stops the pressed position and is inside. Displace to bend. As a result, the piezoelectric elements P1 and P2 attached to the inner surface 3a are displaced together with the housing 3. The amount of displacement of the housing 3 is the largest at the pressed position. Therefore, as shown in FIG. 7A, when the operation region R1 is operated, the displacement amount of the piezoelectric element P1 becomes larger than the displacement amount of the piezoelectric element P2. As a result, as shown in FIG. 7B, the voltage value (voltage amplitude value) of the voltage generated in the piezoelectric element P1 becomes larger than the voltage value (voltage amplitude value) of the voltage generated in the piezoelectric element P2. On the other hand, as shown in FIG. 8A, when the operation region R2 is operated, the displacement amount of the piezoelectric element P2 becomes larger than the displacement amount of the piezoelectric element P1. As a result, as shown in FIG. 8B, the voltage value of the voltage generated in the piezoelectric element P2 becomes larger than the voltage value of the voltage generated in the piezoelectric element P1.

In step S12 shown in FIG. 6, based on the voltage value measured in step S11, the control unit 104 sets the first piezoelectric element having the highest voltage value and the voltage value among the plurality of piezoelectric elements P1 and P2. The second piezoelectric element, which is the second highest after the first piezoelectric element, is specified. As described above, the voltage value of the piezoelectric element whose corresponding operating region has been manipulated is larger than the voltage value of the other piezoelectric element. Therefore, specifying the first piezoelectric element specifies the manipulated operating region. It is synonymous with doing.

In step S12, the control unit 104 identifies the first piezoelectric element and the second piezoelectric element by, for example, comparing the voltage values of the piezoelectric elements P1 and P2. The control unit 104 identifies the first piezoelectric element and the second piezoelectric element by, for example, determining whether the difference between the voltage value of the piezoelectric element P1 and the voltage value of the piezoelectric element P2 is a positive value or a negative value. You may. For example, when the voltage value of the piezoelectric element P1 is higher than the voltage value of the piezoelectric element P2, the control unit 104 identifies that the piezoelectric element P1 is the first piezoelectric element and the piezoelectric element P2 is the second piezoelectric element.

As shown in FIGS. 7 (b) and 8 (b), the voltage amplitudes of the piezoelectric elements P1 and P2 change with time. For example, the control unit 104 treats the peak value (maximum value) of the voltage amplitude of the piezoelectric elements P1 and P2 in the predetermined time range as the voltage value of the piezoelectric elements P1 and P2 at predetermined time intervals, and treats the first piezoelectric element and the first piezoelectric element and the first piezoelectric element 104. (Ii) Identify the piezoelectric element. That is, the control unit 104 treats the peak value (maximum value) of the voltage amplitude of the piezoelectric elements P1 and P2 in the latest one cycle as the voltage value of the piezoelectric elements P1 and P2 in a predetermined cycle, and treats the first piezoelectric element and the second piezoelectric element and the second. The process of identifying the piezoelectric element is repeated.

In step S12, the control unit 104 is configured to identify the first piezoelectric element and the second piezoelectric element, for example, if any of the voltage values measured in step S11 is equal to or higher than a preset threshold value. May be good. The threshold value used in step S12 is set higher than, for example, the noise level of the voltage measured by the measuring unit 101. In this configuration, since the first piezoelectric element and the second piezoelectric element are specified only when there is a high possibility that there is an operation, the piezoelectric switch 1 can be efficiently driven. Specifically, the control unit 104 piezoelectrics the peak value of the voltage amplitude of the piezoelectric elements P1 and P2 in a predetermined time from the time when any of the voltage values measured in the step S11 becomes equal to or higher than the preset threshold value. Treated as the voltage value of the elements P1 and P2, the first piezoelectric element and the second piezoelectric element are specified.

In step S13, the control unit 104 refers to the difference between the voltage value of the first piezoelectric element and the voltage value of the second piezoelectric element specified in step S12, or the voltage value of the first piezoelectric element specified in step S12. The ratio of the voltage values of the second piezoelectric element is calculated, and the presence or absence of an operation on the operation region corresponding to the first piezoelectric element is determined based on the calculated difference or ratio. For example, when the piezoelectric element P1 is the first piezoelectric element, the control unit 104 determines whether or not there is an operation on the operation region R1. When the difference is used, specifically, if the calculated absolute value of the difference is equal to or greater than a preset threshold value with respect to the absolute value of the difference, the control unit 104 determines that there is an operation on the operation area R1. If the absolute value of the difference is less than the threshold value, it is determined that there is no operation on the operation area R1. When the ratio is used, the control unit 104 specifically determines that there is an operation on the operation area R1 if the calculated absolute value of the ratio is equal to or less than a preset threshold value with respect to the absolute value of the ratio. If the absolute value of the ratio exceeds the threshold value, it is determined that there is no operation on the operation area R1.

Here, "there is an operation on the operation area R1" indicates that there is an operation on only the operation area R1. When the operation areas R1 and R2 are operated at the same time, both the voltage value of the first piezoelectric element and the voltage value of the second piezoelectric element become high. Therefore, since the absolute value of the difference is less than the threshold value and the absolute value of the ratio exceeds the threshold value, it is determined that "there is no operation for the operation area R1". That is, in this example, when the operation areas R1 and R2 are operated at the same time, they are treated as erroneous operations.

When the control unit 104 determines that there is an operation on the operation area set corresponding to the first piezoelectric element, for example, the control unit 104 transmits information indicating the operated operation area to the electronic device main body 51. When the control unit 104 determines that there is no operation, for example, the control unit 104 does not transmit any information to the electronic device main body 51. For example, when the operation areas R1 and R2 are set as the volume up switch and the volume down switch, respectively, when the electronic device main body 51 receives the information indicating the operation area from the control unit 104, the electronic device main body 51 adjusts the volume based on the information. .. Specifically, when the electronic device main body 51 receives the information indicating the operation area R1, the volume is increased, and when the information indicating the operation area R2 is received, the volume is decreased.

[Second example]
FIG. 9 is a flowchart showing a driving method of the piezoelectric switch according to the second example. As shown in FIG. 9, the driving method of the piezoelectric switch 1 according to the second example includes steps S21 to S26. In this example, in addition to the presence or absence of an operation on the operation areas R1 and R2, the type of operation on the operation areas R1 and R2 is determined. As the type of operation, for example, there are touch and push classified according to the magnitude of the pressing force pressing the outer surface 3b of the housing 3. Touch is defined as an operation in which the pressing force is less than a predetermined value, and push is defined as an operation in which the pressing force is greater than or equal to a predetermined value. The pressing force of the touch is smaller than the pressing force of the push.

Steps S21 to S23 are performed in the same manner as steps S11 to S13 shown in FIG. That is, in step S21, the measuring unit 101 measures the voltages generated in the plurality of piezoelectric elements P1 and P2, respectively. The measuring unit 101 transmits the voltage values of the piezoelectric elements P1 and P2 to the control unit 104. In step S22, the control unit 104 determines that the first piezoelectric element having the highest voltage value and the first piezoelectric element having the highest voltage value among the plurality of piezoelectric elements P1 and P2 based on the voltage value measured in step S21. The next highest second piezoelectric element is identified. In step S23, the control unit 104 determines the difference between the voltage value of the first piezoelectric element and the voltage value of the second piezoelectric element specified in step S22, or the voltage of the second piezoelectric element with respect to the voltage value of the first piezoelectric element. The ratio of the values is calculated, and based on the calculated difference or ratio, it is determined whether or not there is an operation on the operation region set on the outer surface 3b of the housing 3 corresponding to the first piezoelectric element.

When the control unit 104 determines in step S23 that there is an operation, the control unit 104 transmits a signal to the drive unit 103. When the drive unit 103 receives the signal from the control unit 104, in step S24, the drive unit 103 applies a drive voltage to the piezoelectric element P1 for a predetermined time to vibrate the piezoelectric element P1. The piezoelectric elements P1 and P2 are both attached to the inner surface 3a of the same housing 3. Therefore, when the piezoelectric element P1 vibrates, the housing 3 vibrates, and as a result, the piezoelectric element P2 also vibrates. That is, the vibration of the piezoelectric element P1 is transmitted to the piezoelectric element P2 through the housing 3.

In step S25, the measuring unit 102 measures the voltage generated in the piezoelectric element P2. For example, the measuring unit 102 constantly measures the voltage of the piezoelectric element P2 and transmits the voltage value of the piezoelectric element P2 to the control unit 104. The measuring unit 102 may be configured to measure the voltage of the piezoelectric element P2 and transmit the voltage value of the piezoelectric element P2 to the control unit 104 only when the driving unit 103 vibrates the piezoelectric element P1, for example. In this case, the control unit 104 transmits a signal to the drive unit 103 and at the same time transmits a signal to the measurement unit 102. When the measuring unit 102 receives the signal from the control unit 104, the measuring unit 102 measures the voltage of the piezoelectric element P2 over a predetermined time.

The voltage generated in the piezoelectric element P2 will be described with reference to FIG. FIG. 10A is a cross-sectional view showing a vibration state of the piezoelectric elements P1 and P2 when there is no operation. FIG. 10B is a cross-sectional view showing a vibration state of the piezoelectric elements P1 and P2 when there is an operation. FIG. 10C is a graph showing the difference in voltage amplitude in the piezoelectric element P2. The vertical axis of FIG. 10C shows the voltage amplitude, and the horizontal axis shows the time. In FIG. 10 (c), only one of the continuous pulses is shown.

As shown in FIG. 10A, when there is no operation in the operation areas R1 and R2, the vibration of the piezoelectric element P1 is transmitted to the piezoelectric element P2 through the housing 3 with almost no inhibition. On the other hand, as shown in FIG. 10B, when there is an operation in the operation areas R1 and R2, the vibration of the piezoelectric element P1 is hindered by the finger of the operator who presses the housing 3, and the piezoelectric element P2 Not fully communicated to. Since the vibration of the housing 3 is suppressed by the finger of the operator, the vibration of the piezoelectric element P2 is suppressed. Therefore, when there is an operation, the vibration of the piezoelectric element P2 becomes smaller than when there is no operation, and as a result, the voltage amplitude in the piezoelectric element P2 becomes smaller as shown in FIG. 10 (c).

When the operation type is push, the pressing force of the housing 3 is higher than when the operation type is touch. Therefore, in the case of push, the vibration of the piezoelectric element P1 is further hindered as compared with the case of touch, and it becomes difficult to transmit the vibration to the piezoelectric element P2. Therefore, in the case of push, the vibration of the piezoelectric element P2 becomes smaller than in the case of touch, and as a result, the voltage amplitude in the piezoelectric element P2 becomes smaller as shown in FIG. 10 (c).

Therefore, based on the magnitude of the voltage value of the piezoelectric element P2, it is possible to determine whether or not there is an operation and the type of operation having a different pressing force. The voltage value threshold value Ta used for determining the presence or absence of an operation can be set in advance based on the voltage value of the piezoelectric element P2, for example, when there is an operation and when there is no operation. The threshold value Ta can be set to, for example, an intermediate value between the voltage value when there is an operation and the voltage value when there is no operation. The voltage value threshold value Tb used for determining the type of operation can be set in advance based on, for example, the voltage of the piezoelectric element P2 in the case of touch and the voltage of the piezoelectric element P2 in the case of push. The threshold value Tb can be set to, for example, an intermediate value between the voltage value in the case of touch and the voltage value in the case of push.

In step S26, the control unit 104 determines at least one of the presence / absence of operation and the type of operation for the operation areas R1 and R2 set on the outer surface 3b of the housing 3 based on the voltage value measured in step S25. .. Here, the control unit 104 has already determined in step S23 whether or not there is an operation on the operation areas R1 and R2. Therefore, the control unit 104 determines only the type of operation in step S26. Specifically, if the voltage value of the piezoelectric element P2 is equal to or higher than the preset threshold value Tb, the control unit 104 determines that the operation type is touch, and the voltage value of the piezoelectric element P2 is less than the threshold value Tb. If so, it is determined that the operation type is push. The case where the control unit 104 determines whether or not there is an operation in step S26 will be described later.

When the control unit 104 determines the type of operation in step S26, the electronic device main body provides information indicating the operation region corresponding to the first piezoelectric element specified in step S22 and information indicating the type of operation determined in step S26. Send to 51. In this example, for example, the operation area R1 can function as two different switches. For example, the operation area R1 functions as a volume up switch by touch, and functions as an AI (artificial intelligence) assistant activation switch by push. Similarly, the operation area R2 can also function as two different switches. For example, the operation area R2 functions as a volume down switch by touch and a power switch by push.

In the second example, the types of operations classified according to the magnitude of the pressing force have been described, but the control unit 104 determines the types of operations classified according to the length of the pressing time instead of the magnitude of the pressing force. You may. When the pressing time for the operator's finger to press the outer surface 3b of the housing 3 is long, the time when the voltage value of the piezoelectric element P2 is less than the threshold value Ta becomes long. Therefore, if the voltage value of the piezoelectric element P2 is less than the threshold value Ta for a predetermined time or longer, the control unit 104 determines that the operation is a long touch, and the voltage value of the piezoelectric element P2 is less than the threshold value Ta. If the time is less than a predetermined time, it may be determined that the operation is a mere touch (tap). Even in this case, for example, the operation areas R1 and R2 can be made to function as two different switches.

Further, the control unit 104 may determine both the type of operation classified by the magnitude of the pressing force and the type of the operation classified by the length of the pressing time. In this case, the control unit 104 determines a simple touch, a long touch, a simple push, and a long push. As a result, each of the operation areas R1 and R2 can function as four different switches.

Further, the driving method of the piezoelectric switch 1 according to the second example does not include steps S21 to S23, and in step S24, the driving unit 103 applies a driving voltage to the piezoelectric element P1 regardless of the presence or absence of operation, and the piezoelectric element P1 May be configured to vibrate. In this case, the drive circuit 100 does not have to include the measuring unit 101. For example, the drive unit 103 constantly applies a drive voltage to the piezoelectric element P1 to vibrate the piezoelectric element P1. In step S26, the control unit 104 first determines whether or not there is an operation. Specifically, the control unit 104 determines that there is no operation when the voltage value of the piezoelectric element P2 is equal to or higher than the preset threshold value Ta, and there is an operation when the voltage value of the piezoelectric element P2 is less than the threshold value Ta. To determine. When the control unit 104 determines that the voltage value of the piezoelectric element P2 is less than the threshold value Ta and there is an operation, the control unit 104 further determines the type of operation. Specifically, if the voltage value of the piezoelectric element P2 is equal to or higher than the preset threshold value Tb, the control unit 104 determines that the operation type is touch, and the voltage value of the piezoelectric element P2 is less than the threshold value Tb. If so, it is determined that the operation type is push.

[Third example]
FIG. 11 is a flowchart showing a driving method of the piezoelectric switch according to the third example. As shown in FIG. 10, the method for driving the piezoelectric switch 1 according to the third example includes steps S31 to S35. In this example, the operating area R3 (see FIG. 2) is used.

In step S31, similarly to steps S11 and S21 (see FIGS. 6 and 9), the measuring unit 101 measures the voltages generated in the plurality of piezoelectric elements P1 and P2, respectively. The measuring unit 101 transmits the voltages of the piezoelectric elements P1 and P2 to the control unit 104. In step S32, the control unit 104 determines whether or not there is an operation on the operation area R3 set on the outer surface 3b of the housing 3 based on the voltage value measured in step S31. For example, the control unit 104 determines that there is an operation when any of the voltage values measured in step S31 is equal to or higher than a preset threshold value, and determines that there is no operation when the voltage value is less than the threshold value. This threshold is set higher than, for example, the noise level of the voltage.

Steps S33 to S35 are performed in the same manner as steps S24 to S26 shown in FIG. That is, when the control unit 104 determines that there is an operation in the step S32, the control unit 104 applies a driving voltage to the piezoelectric element P1 in the step S33 to vibrate the piezoelectric element P1. In step S34, the measuring unit 102 measures the voltage generated in the piezoelectric element P2. In step S35, the control unit 104 determines at least one of the presence / absence of operation and the type of operation based on the voltage value measured in step S34. Here, the control unit 104 has already determined in step S32 whether or not there is an operation on the operation area R3. Therefore, the control unit 104 determines only the type of operation in step S35. The case where the control unit 104 determines whether or not there is an operation in step S35 will be described later. When the control unit 104 determines the type of operation in step S35, the control unit 104 transmits information indicating the type of operation to the electronic device main body 51.

In the third example, the types of operations classified according to the magnitude of the pressing force have been described, but the control unit 104 determines the types of operations classified according to the length of the pressing time instead of the magnitude of the pressing force. You may. Further, the control unit 104 may determine both the type of operation classified by the magnitude of the pressing force and the type of the operation classified by the length of the pressing time.

Further, the driving method of the piezoelectric switch 1 according to the third example does not include steps S31 and S32, and in step S33, the driving unit 103 applies a driving voltage to the piezoelectric element P1 regardless of whether or not there is an operation, and the piezoelectric element P1 May be configured to vibrate. In this case, the drive circuit 100 does not have to include the measuring unit 101. For example, the drive unit 103 constantly applies a drive voltage to the piezoelectric element P1 to vibrate the piezoelectric element P1. In step S35, the control unit 104 first determines whether or not there is an operation. Specifically, the control unit 104 determines that there is no operation when the voltage value of the piezoelectric element P2 is equal to or higher than the preset threshold value Ta, and there is an operation when the voltage value of the piezoelectric element P2 is less than the threshold value Ta. To determine. When the control unit 104 determines that the voltage value of the piezoelectric element P2 is less than the threshold value Ta and there is an operation, the control unit 104 further determines the type of operation. Specifically, if the voltage value of the piezoelectric element P2 is equal to or higher than the preset threshold value Tb, the control unit 104 determines that the operation type is touch, and the voltage value of the piezoelectric element P2 is less than the threshold value Tb. If so, it is determined that the operation type is push.

As described above, in the driving method and the driving circuit 100 of the piezoelectric switch 1 according to the first example, the plurality of piezoelectric elements P1 and P2 are attached to the inner surface 3a of the housing 3 so as to be separated from each other, and the housing 3 The corresponding portions on the outer surface 3b function as operation areas R1 and R2, respectively. When the operation areas R1 and R2 are operated, the displacement amount of the piezoelectric elements P1 and P2 corresponding to the operated operation areas R1 and R2 becomes the largest. Therefore, in order to specify the operated operation region, the voltage generated in each of the plurality of piezoelectric elements P1 and P2 is measured, and the first piezoelectric element having the highest voltage value is specified based on the measured voltage value. Thereby, the operated operation area can be specified. Further, the second piezoelectric element having the next highest voltage value after the first piezoelectric element is identified, and the difference between the voltage value of the first piezoelectric element and the voltage value of the second piezoelectric element, or the voltage value of the first piezoelectric element. Based on the ratio of the voltage values of the second piezoelectric element, it is determined whether or not there is an operation in the specified operation region. As a result, noise on the voltage value and the influence of erroneous operation can be suppressed. As a result, the manipulated operating area can be accurately identified.

When the difference is used, in step S13, the control unit 104 determines that there is an operation if the absolute value of the difference is equal to or greater than a preset threshold value. When the ratio is used, in step S13, the control unit 104 determines that there is an operation if the absolute value of the ratio is equal to or less than a preset threshold value. Thereby, it is possible to easily determine whether or not there is an operation on the operation area.

In step S12, the control unit 104 treats the peak value of the voltage amplitude of the piezoelectric elements P1 and P2 in a predetermined time range as the voltage value of the piezoelectric elements P1 and P2, and identifies the first piezoelectric element and the second piezoelectric element. Thereby, the first piezoelectric element and the second piezoelectric element can be accurately specified.

In the driving method and the driving circuit 100 of the piezoelectric switch 1 according to the second example and the third example, the piezoelectric elements P1 and P2 are both attached to the inner surface 3a of the housing 3. Therefore, when the piezoelectric element P1 vibrates, the vibration is transmitted to the piezoelectric element P2 through the housing 3. The ease with which vibration is transmitted differs depending on whether or not there is an operation on the operation areas R1, R2, and R3 on the outer surface 3b of the housing 3 and the type of operation. Therefore, in steps S24 and S33, the drive unit 103 vibrates the piezoelectric element P1, and in steps S25 and S34, the measuring unit 102 measures the voltage generated in the piezoelectric element P2. Then, based on the measured voltage value, in steps S26 and S35, the control unit 104 determines at least one of the presence / absence of operation and the type of operation for the operation areas R1, R2, and R3.

In steps S26 and S35, the control unit 104 determines the presence or absence of an operation and the type of operation using the threshold value Ta and the threshold value Tb based on the piezoelectric value of the piezoelectric element P2. Therefore, the presence or absence of the operation and the type of the operation can be easily determined.

In step S31, the measuring unit 101 measures the voltage generated in the piezoelectric element P1 and the piezoelectric element P2, respectively, and in step S332, the control unit 104 measures the voltage value of the piezoelectric element P1 and the voltage of the piezoelectric element P2 measured in step S31. Whether or not there is an operation is determined based on the value. Steps S33 to S35 are performed when it is determined in step S32 that there is an operation. Therefore, the piezoelectric element P1 vibrates only when it is determined that there is an operation. Therefore, power consumption can be suppressed. Further, it is possible to suppress the generation of noise caused by the vibration of the piezoelectric element P1.

In step S21, the measuring unit 101 measures the voltage generated in the piezoelectric element P1 and the piezoelectric element P2, respectively, and in step S23, the control unit 104 measures the voltage value of the piezoelectric element P1 and the voltage of the piezoelectric element P2 measured in step S21. Whether or not there is an operation is determined based on the value. Moreover, the control unit 104 specifies the operated operation region by specifying the first piezoelectric element and the second piezoelectric element in step S22. As described above, in the second example, not only the presence or absence of the operation is determined, but also the operation area is specified. Steps S24 to S26 are performed when it is determined in step S23 that there is an operation. Therefore, the piezoelectric element P1 vibrates only when it is determined that there is an operation. Therefore, power consumption can be suppressed. Further, it is possible to suppress the generation of noise caused by the vibration of the piezoelectric element P1.

In the piezoelectric switch 1, the piezoelectric elements P1 and P2 are arranged on the wiring member 2 so as to be separated from each other. Therefore, when the piezoelectric switch 1 is driven by the driving method and the driving circuit 100 of the second or third example, the vibration of the piezoelectric element P1 is transmitted to the piezoelectric element P2 not only through the housing 3 but also through the wiring member 2. To. Since the wiring member 2 is connected to the main surface Pa of the piezoelectric elements P1 and P2, it is separated from the housing 3 to which the main surface Pb of the piezoelectric elements P1 and P2 is attached. Therefore, the vibration transmitted through the wiring member 2 is unlike the vibration transmitted through the housing 3, and is unlikely to change depending on the presence or absence of operation on the operation areas R1, R2, and R3. Therefore, the vibration transmitted through the wiring member 2 becomes noise when determining the presence or absence of operation. Therefore, in the piezoelectric switch 1, the arrangement interval L2 of the piezoelectric elements P1 and P2 in the wiring member 2 is longer than the length L1 of the piezoelectric elements P1 and P2. As a result, the vibration of the piezoelectric element P1 is attenuated while being transmitted to the piezoelectric element P2 through the wiring member 2. As a result, even when the piezoelectric switch 1 is driven by the driving methods and the driving circuit 100 of the second and third examples, the presence or absence of operation can be accurately determined.

In the wiring member 2, the second wiring portion 22 is connected to the first wiring portion 21 between the piezoelectric element P1 and the piezoelectric element P2. Therefore, the vibration of the piezoelectric element P1 is further attenuated while being transmitted to the piezoelectric element P2 through the wiring member 2. Thereby, even when the piezoelectric switch 1 is driven by the driving methods and the driving circuit 100 of the second and third examples, the presence or absence of operation can be determined more accurately.

Since the active region Ra of the piezoelectric element P2 is arranged closer to the piezoelectric element P1, the vibration of the piezoelectric element P1 transmitted through the housing 3 is attenuated as compared with the case where the active region Ra of the piezoelectric element P2 is arranged closer to the opposite side of the piezoelectric element P1. It is hard to be done. As a result, even when the piezoelectric switch 1 is driven by the driving methods and the driving circuit 100 of the second and third examples, the operation can be determined more accurately.

The piezoelectric element P1 and the piezoelectric element P2 are attached to the inner surface 3a of the housing 3 so as to be displaced together with the housing 3 when the operation areas R1, R2, and R3 are pressed. Therefore, even when the piezoelectric switch 1 is driven by the driving methods and the driving circuit 100 of the second and third examples, at least one of the piezoelectric element P1 and the piezoelectric element P2 is determined whether or not the operation areas R1, R2, and R3 are operated. It can also be discriminated by the voltage generated in.

The present invention is not necessarily limited to the above-described embodiment, and various modifications can be made without departing from the gist thereof.

The piezoelectric elements P1 and P2 may be laminated piezoelectric elements in which a plurality of piezoelectric layers are laminated via internal electrodes. The wiring member 2 has at least one of the conductor layers 31 and 33, one of the conductor layers 32 and 34, one of the conductor layers 35 and 37, and one of the conductor layers 36 and 38, respectively. Just do it. In this case, the measuring unit 101 and the driving unit 103 can be connected to the same conductor layer, and the measuring unit 101 and the measuring unit 102 can be connected to the same conductor layer. The piezoelectric switch 1 may include three or more piezoelectric elements.

1 ... Piezoelectric switch, 2 ... Wiring member, 3 ... Housing, 3a ... Inner surface, 3b ... Outer surface, 21 ... First wiring unit, 22 ... Second wiring unit, 100 ... Drive circuit, 101 ... Measurement unit, 102 ... Measurement Unit, 103 ... Drive unit, 104 ... Control unit, P1 ... Piezoelectric element, P2 ... Piezoelectric element, Pa ... Main surface, Pb ... Main surface, Ra ... Active region, R1 ... Operation area, R2 ... Operation area.

Claims (7)

It is a driving method of a piezoelectric switch including a plurality of piezoelectric elements that are attached to the inner surface of the housing apart from each other and each of the corresponding portions on the outer surface of the housing functions as an operation area.
The process of measuring the voltage generated in each of the plurality of piezoelectric elements, and
Based on the voltage value measured in the measurement step, the first piezoelectric element having the highest voltage value and the second piezoelectric element having the next highest voltage value after the first piezoelectric element among the plurality of piezoelectric elements. The process of identifying, and
A step of determining whether or not there is an operation on the operation region corresponding to the first piezoelectric element based on the difference between the voltage value of the first piezoelectric element and the voltage value of the second piezoelectric element specified in the specifying step. And, including, how to drive a piezoelectric switch. The method for driving a piezoelectric switch according to claim 1, wherein in the step of determining, if the absolute value of the difference is equal to or greater than a preset first threshold value, it is determined that the operation is performed. It is a driving method of a piezoelectric switch including a plurality of piezoelectric elements that are attached to the inner surface of the housing apart from each other and each of the corresponding portions on the outer surface of the housing functions as an operation area.
The process of measuring the voltage generated in each of the plurality of piezoelectric elements, and
Based on the voltage value measured in the measurement step, the first piezoelectric element having the highest voltage value and the second piezoelectric element having the next highest voltage value after the first piezoelectric element among the plurality of piezoelectric elements. The process of identifying, and
A step of determining whether or not there is an operation on the operation region corresponding to the first piezoelectric element based on the ratio of the voltage value of the second piezoelectric element to the voltage value of the first piezoelectric element specified in the specifying step. How to drive a piezoelectric switch, including. The method for driving a piezoelectric switch according to claim 3, wherein in the step of determining, if the absolute value of the ratio is equal to or less than a preset first threshold value, it is determined that the operation is performed. The specifying step identifies the first piezoelectric element and the second piezoelectric element when any of the voltage values measured in the measuring step is equal to or higher than a preset second threshold value. The method for driving a piezoelectric switch according to any one of 1 to 4. It is a drive circuit of a piezoelectric switch provided with a plurality of piezoelectric elements mounted on the inner surface of the housing separated from each other and having corresponding portions on the outer surface of the housing function as operation regions.
A measuring unit that measures the voltage generated in each of the plurality of piezoelectric elements,
Based on the voltage value measured by the measuring unit, the first piezoelectric element having the highest voltage value and the second piezoelectric element having the next highest voltage value after the first piezoelectric element among the plurality of piezoelectric elements. And a control unit that determines whether or not there is an operation on the operation region corresponding to the first piezoelectric element based on the difference between the voltage value of the first piezoelectric element and the voltage value of the second piezoelectric element. The drive circuit of the piezoelectric switch. It is a drive circuit of a piezoelectric switch including a plurality of piezoelectric elements mounted on the inner surface of a housing separated from each other and having corresponding portions on the outer surface of the housing function as operation regions.
A measuring unit that measures the voltage generated in each of the plurality of piezoelectric elements,
Based on the voltage value measured by the measuring unit, the first piezoelectric element having the highest voltage value and the second piezoelectric element having the next highest voltage value after the first piezoelectric element among the plurality of piezoelectric elements. Based on the ratio of the voltage value of the second piezoelectric element to the voltage value of the first piezoelectric element, a control unit that determines whether or not there is an operation on the operation region corresponding to the first piezoelectric element. A drive circuit for a piezoelectric switch.

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