JP7243517B2 - vibration unit - Google Patents

Description

The present invention relates to vibrating units.

2. Description of the Related Art Conventionally, there has been known a technique of expanding and contracting a piezoelectric body and converting the expansion and contraction into vibration. Patent Literatures 1 and 2 below disclose a vibration unit equipped with a piezoelectric vibrator that detects a pressing force when a panel is pressed by a finger and generates tactile vibration in the panel. . In the vibration units disclosed in these documents, a plurality of piezoelectric vibrators are aligned under one panel, and press detection and oscillation are performed in each area where the piezoelectric vibrators are arranged.

JP 2019-062025 A JP 2019-058848 A

The inventors have conducted extensive research on the detection of pressing of piezoelectric vibrators, and have found a new technique capable of suppressing variations in the detection of pressing between a plurality of piezoelectric vibrators.

SUMMARY OF THE INVENTION An object of the present invention is to provide a vibration unit capable of suppressing variations in press detection among a plurality of piezoelectric vibrators.

A vibration unit according to one aspect of the present invention includes a base substrate, a plurality of piezoelectric vibrators provided on the main surface of the base substrate and capable of vibrating in the thickness direction of the base substrate, and a panel extending in parallel to integrally cover the plurality of piezoelectric vibrators and with which each of the piezoelectric vibrators abuts; each piezoelectric vibrator generates a voltage corresponding to the pressing force when pressed through the panel; The panel outputs a signal and vibrates when a predetermined drive voltage signal is input, and the panel includes a plurality of first regions facing the plurality of piezoelectric vibrators and a second region positioned between the adjacent first regions. and the thickness of the second region is thicker than the thickness of the first region.

In the vibration unit described above, when the panel is flexed, the contact state between the piezoelectric vibrators and the panel changes among the plurality of piezoelectric vibrators, and as a result, even when pressed with the same pressure. In addition, variations may occur in voltage signals output among a plurality of piezoelectric vibrators. In the vibration unit described above, the second region of the panel is thicker than the first region, thereby increasing the rigidity. Therefore, the situation in which the panel is flexed is suppressed, and variations in the press detection among the plurality of piezoelectric vibrators are suppressed.

In another aspect of the vibration unit, the panel has a protruding portion that protrudes away from the base substrate in the first region. In this case, the feedback can be transmitted without delay, and the touch of the first area can be intuitively felt by touch.

In the vibration unit according to another aspect, the separation distance between the panel and the base substrate in the second region is shorter than the displacement amount at which the piezoelectric vibrator detects a depression. In this case, the sensing of the vibration unit is turned off on the second area when the finger moves between the first areas while pressing the finger.

In another aspect of the vibration unit, the base substrate further includes a plurality of pedestals on which the plurality of piezoelectric vibrators are respectively mounted. In this case, the influence of assembly variation on sensing and feedback can be minimized.

In a vibrating unit according to another aspect, each piezoelectric vibrator is energized by a panel. In this case, feedback can be transmitted without delay, and the touch of the first area can be intuitively felt by touch. In addition, it is possible to suppress the displacement of the piezoelectric element.

According to the present invention, there is provided a vibrating unit capable of suppressing variations in press detection among a plurality of piezoelectric vibrators.

FIG. 1 is a schematic perspective view of a vibrating unit according to an embodiment. 2 is an exploded perspective view of the vibration unit shown in FIG. 1. FIG. FIG. 3 is a cross-sectional view of the vibrating unit of FIG. 1 taken along line III-III. 4 is a schematic perspective view showing the lower surface of the panel of FIG. 1. FIG. 5 is an enlarged view of a main part of FIG. 3. FIG. FIG. 6 is a graph showing temporal changes in the output voltage of the piezoelectric vibrator. FIG. 7 is a block diagram showing the configuration of the control unit. 8 is a graph showing the output voltage of the drive circuit of FIG. 7. FIG. FIG. 9 is a cross-sectional view showing a vibrating unit according to the prior art. FIG. 10 is a schematic perspective view showing a vibrating unit in a different mode. 11 is a schematic perspective view showing the underside of the panel of FIG. 10; FIG. FIG. 12 is a schematic perspective view showing a vibrating unit in a different mode. FIG. 13 is a schematic perspective view showing a vibrating unit in a different mode.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated in detail, referring an accompanying drawing. The same or equivalent elements are denoted by the same reference numerals, and redundant description will be omitted.

First, the overall configuration of the vibrating unit 1 according to the embodiment will be described with reference to FIGS. 1 to 4. FIG.

The vibration unit 1 includes a base substrate 10, a plurality of piezoelectric vibrators 20, a panel 30, and a controller 50, as shown in FIG.

As shown in FIGS. 2 and 3, the base substrate 10 has a rectangular plate-like outer shape in this embodiment, and has an upper surface 10a and a lower surface 10b parallel to each other. Base substrate 10 is made of an insulating material having a relatively high elastic modulus, and may be made of acrylic resin, for example.

The base substrate 10 has a plurality of pedestals 12 on the upper surface 10a side. In this embodiment, seven pedestals 12 are arranged in a cross shape. Each pedestal 12 has an annular shape when viewed from the thickness direction of the base substrate 10 . An upper end surface 12a of each pedestal portion 12 is flat, and a piezoelectric vibrator 20, which will be described later, is mounted on the upper end surface 12a. Each pedestal portion 12 has a trapezoidal cross-section whose width gradually narrows upward, and a side surface 12b is inclined. By inclining the side surface 12b of the pedestal portion 12 at an obtuse angle, it is possible to effectively prevent a situation in which the wiring, which will be described later, that connects the piezoelectric vibrator 20 and the control portion 50 is greatly bent and disconnected. The base substrate 10 has a plurality of through holes 14 extending in the thickness direction at respective positions of the plurality of pedestals 12 . In this embodiment, each through hole 14 has a circular cross section.

Each of the plurality of piezoelectric vibrators 20 includes a piezoelectric element 22 and a vibration plate 24, as shown in FIG. In this embodiment, seven piezoelectric vibrators 20 are mounted on the upper end surfaces 12a of the seven pedestals 12, respectively.

The diaphragm 24 is a plate-like member, and has a disc shape in this embodiment. The diaphragm 24 is in contact with the upper end surface 12 a of the base portion 12 and closes the upper opening of the through hole 14 on the base portion 12 . The diameter of the diaphragm 24 is designed to be larger than the diameter of the through hole 14 and to be the same as or slightly smaller than the outer diameter of the upper end surface 12a of the pedestal 12 . Diaphragm 24 is arranged concentrically with respect to pedestal 12 and through hole 14 when viewed from the thickness direction of base substrate 10 . Diaphragm 24 can be made of, for example, Ni--Fe alloy, Ni, brass, stainless steel, or the like.

The piezoelectric element 22 is a sheet-like member, and has a circular sheet shape in this embodiment. The piezoelectric element 22 is adhered to the upper surface 24 a of the diaphragm 24 . The piezoelectric element 22 is arranged concentrically with respect to the diaphragm 24 when viewed from the thickness direction of the base substrate 10 . The diameter of the piezoelectric element 22 is designed to be smaller than the diameter of the diaphragm 24 and smaller than the diameter of the through hole 14 .

Each piezoelectric element 22 is composed of a thin-film piezoelectric body (not shown) and a pair of external electrodes. The pair of external electrodes are provided so as to sandwich the piezoelectric body in the thickness direction of the piezoelectric element 22 . When a predetermined pressure is applied to each piezoelectric element 22, an electromotive force is generated due to the displacement (bending, etc.) of the piezoelectric body, and the electromotive force causes a potential difference between the pair of external electrodes. Each piezoelectric element 22 expands and contracts in the surface direction (direction perpendicular to the thickness direction) when a predetermined voltage is applied between the pair of external electrodes. The piezoelectric body may have a single-layer structure of piezoelectric layers, or may have a multi-layer structure in which piezoelectric layers and internal electrode layers are alternately laminated.

An external electrode of each piezoelectric element 22 is connected to the controller 50 of the vibration unit 1 via a predetermined wiring. The control unit 50 can be configured by a circuit including a CPU and various elements. A flexible printed circuit board (FPC), for example, can be used for the wiring. The control unit 50 is configured to detect the potential difference between the external electrodes caused by the electromotive force when a predetermined pressure is applied to each piezoelectric element 22 . Further, the control unit 50 is configured to apply a voltage between the external electrodes of the piezoelectric element 22 so as to expand and contract the piezoelectric element 22 in the planar direction. When the vibration plate 24 bends in the thickness direction as the piezoelectric element 22 expands and contracts in the plane direction, the piezoelectric vibrator 20 vibrates in the thickness direction. Since the piezoelectric vibrator 20 is arranged so as to straddle the through hole 14 of the base substrate 10 , the through hole 14 allows vibration of the piezoelectric vibrator 20 in the thickness direction to some extent.

As shown in FIG. 2, the panel 30 has a rectangular plate-like outer shape in this embodiment. The panel 30 has substantially the same dimensions as the base substrate 10 when viewed in the thickness direction. The panel 30 is arranged parallel to the upper surface 10 a of the base substrate 10 . The panel 30 is configured such that the upper surface 30a can be touched by a human finger or the like. Panel 30 has a relatively low modulus of elasticity such that sufficient bending deformation occurs upon contact. Panel 30 can be made of a resin material such as polycarbonate, for example.

The panel 30 is adhered to the base substrate 10 with an adhesive 60 at its periphery. The thickness of the adhesive material 60 is designed to be thinner than the separation distance between the panel 30 and the base substrate 10 when the piezoelectric vibrators 20 are in contact with the panel 30 . The thickness of the adhesive material 60 can be designed to be thinner than the thickness of the piezoelectric vibrator 20, for example. Therefore, when the panel 30 and the base substrate 10 are bonded together, each piezoelectric vibrator 20 is urged by the panel 30 with a constant pressure. Therefore, the feedback can be transmitted without delay, and the touch of the first region 31 described later can be intuitively felt with a tactile sense, and the displacement of the piezoelectric element 22 can be suppressed.

The panel 30 has a plurality of first regions 31, second regions 32 and peripheral regions 33, as shown in FIGS. In this embodiment, panel 30 has seven first regions 31 . Each first region 31 is a region facing the piezoelectric vibrator 20, and is a region in which the lower surface 30b is recessed in a circular shape. The first regions 31 are arranged in a cross shape so as to correspond to the piezoelectric vibrators 20 . The diameter of each first region 31 is designed to be larger than the diameter of the diaphragm 24 of the piezoelectric element 22 . Therefore, as shown in FIG. 3, each piezoelectric vibrator 20 is accommodated in the recess of each first region 31, and in the first region 31, the piezoelectric element 22 of each piezoelectric vibrator 20 is located on the lower surface 30b of the panel 30. abut.

The second area 32 is a residual area of the first area 31 in the panel 30 and occupies the periphery of the first area 31 and between adjacent first areas 31 . The thickness T2 of the second region 32 is thicker than the thickness T1 of the first region 31 . For example, the thickness T1 of the first region 31 is 0.3 to 0.5 mm (0.3 mm as an example), and the thickness T2 of the second region 32 is 1 mm or more (1 mm as an example). Therefore, the first region 31 is relatively easy to bend, and pressure and vibration of the piezoelectric vibrator 20 at the time of contact are easily transmitted. On the other hand, the second region 32 is relatively difficult to bend and has increased rigidity.

The peripheral edge area 33 is a rectangular annular area forming the outer edge of the panel 30 . In this embodiment, the thickness of the peripheral region 33 is designed to be the same as the thickness T2 of the second region 32 .

The panel 30 is adjacent to the base substrate 10 in the thickened second region 32 . The panel 30 in the second region 32 may be in contact with the base substrate 10 or may be separated by a predetermined distance D. The distance D can be designed to be shorter than the amount of displacement of the piezoelectric vibrator 20 when the voltage generated in the piezoelectric vibrator 20 reaches a first threshold, which will be described later.

The panel 30 has a raised portion 35 on the upper surface 30a as shown in FIG. The raised portion 35 is provided in a region corresponding to the piezoelectric element 22 of each piezoelectric vibrator 20 . In other words, a plurality of (seven in this embodiment) raised portions 35 are provided.

Next, operation of the vibrating unit 1 will be described with reference to FIGS.

As described above, the upper surface 30a of the panel 30 can be touched with a finger or the like, and each piezoelectric vibrator 20 can be pressed through the panel 30 as shown in FIG. For example, by sliding the finger while pressing the panel 30 with a predetermined pressure, the plurality of piezoelectric vibrators 20 can be pressed continuously.

When the piezoelectric element 22 of each piezoelectric vibrator 20 is pushed by a finger, it outputs a voltage signal as shown in the graph of FIG. Each piezoelectric element 22 outputs a predetermined negative voltage signal because it is energized with a constant pressure by the panel 30 before it is pressed by a finger (unpressed phase PH0).

When the piezoelectric element 22 starts to be pressed by a finger, the negative voltage value gradually increases (pressing phase PH1). In the pressing phase PH1, when the negative voltage value becomes a predetermined voltage threshold (absolute value) and reaches the vibration point V1, the control unit 50 switches the piezoelectric element 22 from the sensor mode to the drive mode. Specifically, as shown in FIG. 7, the control unit 50 switches the circuit connected to the piezoelectric element 22 from the sensor circuit 52 to the drive circuit 53 by the switching circuit 51 . The sensor circuit 52 is a circuit that receives the voltage signal output from the piezoelectric element 22 . The drive circuit 53 is a circuit that applies a drive voltage signal for one pulse as shown in FIG. When a drive voltage signal is applied between the external electrodes of the piezoelectric element 22 from the drive circuit 53, the piezoelectric body of the piezoelectric element 22 expands and contracts in the plane direction, and accordingly the vibration plate 24 bends in the thickness direction. Vibration in the thickness direction occurs in the piezoelectric vibrator 20 . At this time, the first region 31 of the panel 30 is vibrated to the extent that it can be felt by a finger or the like. After the drive circuit 53 gives the drive voltage signal to the piezoelectric element 22 , the control unit 50 switches from the drive circuit 53 to the sensor circuit 52 .

After the pressing phase PH1 in which the piezoelectric element 22 is pressed beyond the vibration point V1, the piezoelectric element 22 shifts to the releasing phase PH2 in which the finger moves away from the panel 30. FIG. In the release phase PH2, the negative voltage value gradually decreases and then the positive voltage value gradually increases. This is because the first region 31 of the panel 30 locally bends toward the upper surface 30a due to the rebound of the finger away from the panel 30 . In the release phase PH2, when the positive voltage value becomes a predetermined voltage threshold (absolute value) and reaches the vibration point V2, the control unit 50 switches the piezoelectric element 22 again from the sensor mode to the drive mode. Then, the driving circuit 53 applies a driving voltage signal for one pulse as shown in FIG. 8 to the piezoelectric element 22 to vibrate the piezoelectric element 22 . At this time, the first region 31 of the panel 30 is vibrated to the extent that it can be felt by a finger or the like.

When the release phase PH2 ends and the finger is completely removed from the panel 30, the piezoelectric element 22 transitions to a convergence phase PH3 in which the panel 30 returns to its original state. In the convergence phase PH3, the panel 30 bends toward the lower surface 30b due to the reaction, and a negative voltage value can be output. In the convergence phase PH3, when the panel 30 completely returns to its original state, the piezoelectric element 22 is energized by a constant pressure from the panel 30 and outputs a predetermined negative voltage signal, as in the unpressed phase PH0. .

When the vibrating unit 1 operates as described above, it gives the user using the vibrating unit 1 the following response.

That is, when the user presses down the first region 31 of the panel 30 with a pressure that causes the piezoelectric element 22 to generate a voltage value equal to or higher than the threshold value of the vibration point V1, the piezoelectric element 22 vibrates, and the user can feel the vibration. do. Also, when the user stops pressing the first region 31 by, for example, sliding his or her finger, a voltage value equal to or higher than the threshold value of the vibration point V2 is generated in the piezoelectric element 22, causing the piezoelectric element 22 to vibrate. touches its vibrations. In other words, the user can feel a pressing feeling (touch feeling, click feeling, operation feeling) both when pressing the finger against the panel 30 and when releasing the finger from the panel 30 .

In the vibrating unit 1 described above, the second region 32 of the panel 30 is made thicker than the first region 31 . Here, as shown in FIG. 9, according to the prior art, the second region 32 described above does not exist (that is, it has a uniform thickness, and the thickness of the first region and the thickness of the second region are the same). The panel 30A is likely to bend. In this case, the contact mode between the piezoelectric vibrators 20 and the panel 30A changes among the plurality of piezoelectric vibrators 20. FIG. Specifically, in some piezoelectric vibrators 20 (for example, the piezoelectric vibrator 20 positioned in the center in FIG. 9), the magnitude of the pressure applied from the panel 30 is relatively weakened, or the pressure applied from the panel 30A A situation of separation may occur. In this case, even when the same pressure is applied to the piezoelectric vibrators 20, voltage signals output from the piezoelectric vibrators 20 may vary.

In the vibrating unit 1 described above, the second region 32 of the panel 30 is thicker than the first region 31, thereby increasing the rigidity. Therefore, the bending of the panel 30 is suppressed, the variation in the output voltage (particularly, the voltage value in the pressing phase PH1) among the plurality of piezoelectric vibrators 20 is suppressed, and the variation in pressing detection is suppressed. there is Therefore, the pressing pressure when one piezoelectric vibrator 20 is pressed and reaches the threshold value of the vibration point V1 (that is, the piezoelectric vibrator 20 vibrates), and the pressing pressure when the other piezoelectric vibrator 20 is pressed and the vibration point V1 is The deviation from the pressing pressure when reaching the threshold becomes small.

Further, as shown in FIG. 5, since the first region 31 of the panel 30 is provided with the raised portion 35, the piezoelectric vibrator 20 at the stage (unpressed phase PH0) before the piezoelectric vibrator 20 is pressed by the finger 20 deformation can be relaxed. In addition, the protuberance 35 enables the user to perceive the position of the first area 31 or press the first area 31 even in a blind state by tracing the upper surface 30a of the panel 30 with a finger. can. Furthermore, the protuberance 35 allows feedback to be transmitted without delay, and the touch of the first region 31 can be intuitively felt by touch.

Further, in the vibration unit 1, the piezoelectric vibrator 20 is raised by the pedestal portion 12 of the base substrate 10, so that the base substrate 10 and the panel 30 are separated from each other. Therefore, the degree of freedom in designing the thickness T2 of the second region 32 of the panel 30 is increased, and it becomes easy to adjust the rigidity to a desired level. For example, by increasing the thickness T2 of the second region 32, the rigidity of the panel 30 can be increased. In addition, the pedestal 12 can minimize the influence of variations during assembly on sensing and feedback.

In the vibration unit 1, the separation distance D between the panel 30 and the base substrate 10 in the second region 32 is shorter than the displacement amount of the piezoelectric vibrator 20 when the output voltage of the piezoelectric vibrator 20 reaches the vibration point V1. It's becoming Therefore, sensing of the vibration unit 1 is turned off on the second area 32 when the finger moves between the adjacent first areas 31 while pressing the finger.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and may be modified or applied to others within the scope of not changing the gist described in each claim.

For example, the shapes of the first region and the second region of the panel are not limited to the shapes described above, and can be variously modified. As shown in FIGS. 10 and 11, a panel 30B in which the second regions 32 are provided in a grid pattern can be used.

The panel 30B has fifteen first regions 31 arranged in a matrix of three rows and five columns. Each first region 31 is a region in which the lower surface 30b is recessed in a square shape. Seven of the fifteen first regions 31 correspond to seven piezoelectric elements 22 arranged in a cross shape. The dimensions of each first region 31 are designed to be larger than the diameter of the diaphragm 24 of the piezoelectric element 22 . Therefore, as shown in FIG. 10, each piezoelectric vibrator 20 is accommodated in the recess of each first region 31, and in the first region 31, the piezoelectric element 22 of each piezoelectric vibrator 20 is located on the lower surface 30b of the panel 30B. abut.

The second region 32 is a residual region of the first region 31 in the panel 30B, and has a lattice shape that divides the first region 31 . In the panel 30B, the thickness of the second region 32 is thicker than the thickness of the first region 31, similar to the panel 30 described above. Therefore, in the panel 30B, similarly to the panel 30 described above, the second region 32 is relatively difficult to bend, and the rigidity is enhanced.

Further, the peripheral edge region 33 of the panel 30 does not necessarily have to have the same thickness as the second region 32, and can have the same thickness as the first region 31 as in the panel 30C shown in FIG. . In this case, the thickness of the adhesive material 60 that adheres to the base substrate 10 at the peripheral edge of the panel 30 is increased, and reliable assembly can be achieved. In addition, the binding component (the force with which the panel 30C is attracted to the base substrate 10) from the adhesive 60 to the panel 30C is strengthened, and the adhesive 60 absorbs vibration accompanying external impact and unnecessary vibration of the piezoelectric element 22. can be done.

The panel 30 described above has a thicker peripheral region 33 than the panel 30C shown in FIG. Breakage and displacement of the vibrator 20 can be further suppressed. In addition, in the panel 30 described above, since the thickness of the adhesive 60 is thinner than that of the panel 30C shown in FIG. 12, the adhesive can be easily controlled, and high assembly accuracy can be achieved.

The thickness of the adhesive 60 shown in FIG. 12 can be reduced by increasing the thickness of the base substrate 10 at the portion corresponding to the peripheral edge region 33 of the panel 30C, as shown in FIG. In this case, as the thickness of the adhesive 60 is reduced, the control of the adhesive becomes easier, and higher assembly accuracy can be achieved.

Reference Signs List 1 Vibration unit 10 Base substrate 20 Piezoelectric vibrator 22 Piezoelectric element 24 Diaphragm 30, 30A, 30B Panel 31 First region 32 Second region 33 Peripheral region , 35 . . . ridges.

Claims (5)

a base substrate;
a plurality of piezoelectric vibrators provided on the main surface of the base substrate and capable of vibrating in the thickness direction of the base substrate;
a panel that extends parallel to the main surface of the base substrate, integrally covers the plurality of piezoelectric vibrators, and abuts against each of the piezoelectric vibrators;
each of the piezoelectric vibrators outputs a voltage signal corresponding to the pressing force when pressed through the panel and vibrates when a predetermined drive voltage signal is input;
the panel has a plurality of first regions facing the plurality of piezoelectric vibrators and a second region located between the adjacent first regions;
A vibrating unit, wherein the thickness of the second region is thicker than the thickness of the first region. 2. The vibrating unit according to claim 1, wherein the panel has a ridge that bulges away from the base substrate in the first region. 3. The vibrating unit according to claim 1, wherein the separation distance between the panel and the base substrate in the second region is shorter than the amount of displacement at which the piezoelectric vibrator detects a depression. The vibration unit according to any one of claims 1 to 3, wherein the base substrate further comprises a plurality of pedestals on which the plurality of piezoelectric vibrators are respectively mounted. A vibrating unit according to any preceding claim, wherein each piezoelectric vibrator is biased by the panel.

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