JP2019106280A - Switching device - Google Patents

Abstract

To provide a switching device capable of suppressing destruction of a piezoelectric element.SOLUTION: A switching device 1 includes: a panel 10 to be depressed; a piezoelectric element 20 capable of generating electric power when load due to depressing operation is applied and allowed to be displaced when the electric power is applied; a transmission member 30 for connecting the panel 10 to the piezoelectric element 20 so that the displacement of the panel 10 is transmitted to the piezoelectric element 20; a casing 40 which is a casing for storing the piezoelectric element 20 and includes a groove section 41 by which the displacement of the piezoelectric element 20 is allowed; a stopper structure for restricting the displacement of the piezoelectric element 20 so that the displacement amount of the piezoelectric element 20 does not exceed a maximum allowable displacement amount; a transmission member 30 for connecting the panel 10 to the piezoelectric element 20 so as to transmit mutual displacement; the casing 40 including the groove section 41 in which the displacement of the piezoelectric element 20 is allowed and stored; and a stopper structure for restricting the displacement of the piezoelectric element 20 so that the displacement amount of the piezoelectric element 20 does not exceed the maximum allowable displacement amount.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a switch device, and more particularly to a switch device using a piezoelectric element.

  Conventionally, a switch device is disclosed that turns on a switch by applying a load to a piezo element and applies a touch to the piezo element by delaying power generated by applying a load to the piezo element. (See, for example, Patent Document 1).

  The switch device includes a piezoelectric key switch providing tactile response, a bimorph piezoelectric element fixed at an edge, and a keypad attached to the bimorph piezoelectric element spaced apart from the fixed edge, the keypad Depression causes the element to flex and generate a voltage signal between the grounded metal disk and the electrode. The voltage signal from the electrode is sent to the wire. In response to the voltage signal, a drive circuit provides a drive signal to flex the piezoelectric element and provide upward tactile feedback to the keypad.

JP 10-307661 A

  However, in the prior art, there is a problem that the displacement of the piezoelectric element is minute, and the piezoelectric element may be broken if the displacement by the pressing operation becomes large.

  Therefore, an object of the present invention is to provide a switch device capable of suppressing destruction of a piezo element.

[1] In order to achieve the above object, a panel operated by pressing, a piezoelectric element which generates an electric power when a load is applied by the pressing operation, and a displacement when an electric power is applied, and a displacement of the panel by the piezoelectric element A transmission member for connecting the panel and the piezoelectric element, and a casing for housing the piezoelectric element, the casing having a groove for permitting displacement of the piezoelectric element, and the piezoelectric element And a stopper structure for limiting the displacement of the piezoelectric element so that the displacement of the piezoelectric element does not exceed the maximum allowable displacement.
[2] The switch device according to [1], wherein the groove portion is configured to be shallower than the maximum allowable displacement of the piezoelectric element, and the stopper structure is the groove portion.
[3] The switch device according to [1] or [2], wherein the stopper structure is a limiting portion that limits a transfer load for transferring the displacement of the panel to the piezoelectric element.
[4] The switch device according to [3], wherein the restriction unit restricts the transmission load by restricting the movement of the transmission member.
[5] The switch unit according to the above [3] or [4], wherein the limiting unit limits the transmission load by limiting the displacement amount of the panel.
[6] Further, any one of the above [1] to [5], wherein the maximum allowable displacement amount is a sum of a displacement amount by preloading of the piezoelectric element, a pressing displacement amount of the panel and a driving displacement amount of the piezoelectric element. It may be the switch device described in or 1.

  According to the switch device of the present invention, destruction of the piezo element can be suppressed.

FIG. 1 (a) is a top plan view showing a configuration of a switch device according to a first embodiment of the present invention, and FIG. 1 (b) is a cross-sectional view taken along the line AA of FIG. 1 (a). FIG. 2 is a block diagram of the switch device according to the embodiment of the present invention. FIG. 3A is a cross-sectional view taken along the line A-A of FIG. 1A when the pressing operation is performed, and FIG. 3B is a displacement due to the preload of the piezoelectric element when it is deformed downward by the pressing operation. Only the metal shim and the casing, which show the relationship between the amount X1, the pressure displacement amount X2 deformed by the pressing force of the panel, and the drive displacement amount X3 displaced downward by the voltage drive of the piezoelectric element, and the depth D of the groove It is a fragmentary sectional view shown in figure. Fig.4 (a) is sectional drawing (figure equivalent to AA sectional drawing of Fig.1 (a)) which concerns on the 2nd form of implementation of this invention, and FIG.4 (b) is a pressing. It is sectional drawing at the time of operating. Fig.5 (a) is sectional drawing (figure equivalent to AA sectional drawing of Fig.1 (a)) which concerns on the 3rd form of implementation of this invention, and FIG.5 (b) is a pressing force. It is sectional drawing at the time of operating.

(Embodiment of the present invention)
The switch device 1 according to the embodiment of the present invention includes a panel 10 which is pressed and operated, and a piezoelectric element 20 which generates power when a load is applied and which is displaced when power is applied, and a displacement of the panel 10 A transmitting member 30 for connecting the panel 10 and the piezoelectric element 20 so as to transmit the piezoelectric element 20 to the piezoelectric element 20, and a casing for housing the piezoelectric element 20, wherein the groove 41 is provided to allow displacement of the piezoelectric element 20. A transmission structure for connecting the panel 40 and the piezoelectric element 20 and transmitting the displacement of the casing 40 and the stopper structure for limiting the displacement of the piezoelectric element 20 so that the displacement of the piezoelectric element 20 does not exceed the maximum allowable displacement. 30 and a casing 40 having a groove 41 for accommodating the displacement of the piezoelectric element 20 while being allowed, and the displacement of the piezoelectric element 20 does not exceed the maximum allowable displacement It is configured with a stopper structure for restricting a displacement of the sea urchin piezoelectric element 20.

(Configuration of the first embodiment)
In the first embodiment of the present invention, the above-described groove portion is configured to be shallower than the maximum allowable displacement amount of the piezoelectric element, and the stopper structure is formed as a groove portion.

  As shown in FIGS. 1A and 1B, a metal shim 25 having a diameter larger than that of the piezoelectric element 20 is attached and fixed to the lower surface 20b of the piezoelectric element 20. On the upper surface 20 a of the piezo element 20, for example, a flexible circuit board (FPC) 28 on which electrodes for voltage application to the piezo element 20 and voltage detection are formed is attached.

  The piezoelectric element 20 and the metal shim 25 shown above are attached to the groove 41 of the casing 40. The groove 41 is a stepped groove, in which the outer shape of the metal shim 25 is accommodated, and a stepped portion 42 having an abutting surface 42 a to which the lower surface 25 b of the metal shim 25 can abut is formed. The bottom surface 43 of the groove 41 is formed at a depth having a predetermined distance D from the contact surface 42 a.

  The transmission member 30 is disposed on the piezoelectric element 20, the metal shim 25, and the flexible circuit board (FPC) 28. Further, the panel 10 is disposed on the transmission member 30. At the time of assembly, a preload is added so that the transmission member 30 abuts on the piezo element 20 or the like with a predetermined force so that the transmission member 30 abuts on the piezo element 20 or the like without a gap.

  Therefore, as shown in FIG. 3A, when the region 10b of the transmission member 30 on the upper surface 10a of the panel 10 is pressed by the finger 100, a pressing operation without rattling is possible. The load P due to the pressing operation is transmitted to the piezoelectric element 20 and the metal shim 25 via the transmission member 30.

  Thereby, the piezoelectric element 20 and the metal shim 25 deform and bend downward (in the direction of the bottom surface 43 of the groove portion 41). In addition, when a predetermined voltage is applied in a predetermined direction of the piezoelectric element 20, the piezoelectric element 20 and the metal shim 25 deform and bend downward (in the direction of the bottom surface 43 of the groove portion 41).

The maximum allowable displacement amount X of the piezoelectric element 20 is a displacement amount X ₁ by the preload of the piezoelectric element 20, a pressing displacement amount X ₂ deformed by the pressing force of the panel 10, and a driving displacement displaced downward by voltage drive of the piezoelectric element is the sum of the amount _{X 3.} The depth D of the groove 41 shown above, that is, the distance D from the contact surface 42 a to the bottom surface 43 is set to be smaller than the maximum allowable displacement amount X shown above. Thus, the groove 41 is configured to be shallower than the maximum allowable displacement of the piezo element 20, and the stopper structure can be configured as a groove.

(Panel 10)
The panel 10 is, for example, a plate-like overlay provided with an area 10 b which is operated by the operator with a finger or the like, as shown in FIGS. 1 (a) and 1 (b). The panel 10 is formed of, for example, a resin or the like. The pressing operation on the panel 10 is transmitted to the piezo element 20 via the transmission member 30 described later. Further, the tactile sense presentation when the piezoelectric element 20 is voltage-driven is transmitted to the panel 10 via the transmission member 30 described later. In addition, in FIG. 1 (a), although the operation surface of the panel 10 has circular shape, it is not limited to this.

  The panel 10 functions as an overlay. As shown in FIG. 1B, the panel 10 can be deformed and bent by the pressing operation with the finger 100 in the downward direction, and the load by the pressing operation on the piezo element 20 through the transmission member 30 P can be transmitted.

(Piezo element 20)
The piezoelectric element 20 is a unimorph type in which electrodes (not shown) are attached to both surfaces of the piezoelectric element 20 and bonded and fixed to a metal shim larger than the diameter of the piezoelectric element 20. By applying a voltage to the electrodes, the piezoelectric element 20 expands and contracts, so that the metal shim warps and the entire piezoelectric element 20 and the metal shim 25 bend. In the present embodiment, a predetermined voltage is applied to the piezoelectric element 20 so that the piezoelectric element 20 is bent by a predetermined amount in the pressing direction of FIG. 1B.

  The metal shim 25 has, for example, a plate shape larger than the piezoelectric element 20, as shown in FIGS. 1 (a) and 1 (b). The metal shim 25 is formed of, for example, conductive phosphor bronze or stainless steel.

  The piezoelectric element 20 has, for example, a plate shape as shown in FIGS. 1A and 1B, and is disposed on the upper surface 25 a of the metal shim 25. As a material of the piezoelectric element 20, for example, lithium niobate, barium titanate, lead titanate, lead zirconate titanate (PZT), lead metaniobate, polyvinylidene fluoride (PVDF) or the like is used. The piezoelectric element 20 is, for example, a laminated piezoelectric element formed by laminating films formed using these materials.

  The upper surface 20 a of the piezoelectric element 20 is in contact with the metal shim 25. The piezoelectric element 20 has a first electrode formed on the lower surface 20b. Since the metal shim 25 has conductivity, it is electrically connected to the piezo element 20 as the second electrode.

  When a load P is applied to the panel 10, the piezoelectric element 20 applies the load P to the metal shim 25 through the transmission member 30, and deforms to follow the deformation of the metal shim 25. The piezo element 20 outputs a voltage according to this deformation. When a voltage is applied, the piezo element 20 expands and contracts in response to the applied voltage.

Piezoelectric element 20 is, for example, as shown in FIG. 2, to the control unit 50 a voltage output according to the load P as a load signal S _P. The piezoelectric element 20 is configured to expand and contract according to a voltage based on the drive signal _SD output from the control unit 50, and to deform and bend with the metal shim 25.

  In order to maintain strength by suppressing breakage due to deformation of the piezoelectric element 20, an allowable load is determined, and a maximum allowable displacement amount X corresponding to this is determined. The allowable load (rated load) is the maximum load that can measure the load while maintaining the specifications of the piezoelectric element 20. Therefore, the piezoelectric element 20 is not broken if the load is equal to or less than the allowable load. The initial load (preload) applied to the piezoelectric element 20 is, for example, 1 [N]. The allowable load is, for example, 3 [N].

(Transmission member 30)
The transmission member 30 is provided between the panel 10 and the piezoelectric element 20 as shown in FIGS. 1A and 1B, and functions as a pusher for transmitting a pressing force to the panel 10 to the piezoelectric element 20. The transmission member 30 is formed of, for example, a cylindrical resin or a metal material.

(Casing 40)
The casing 40 supports the piezoelectric element 20, the metal shim 25, the flexible circuit board (FPC) 28 and the like as shown in FIGS. 1A and 1B, and functions as a base for supporting the panel 10. The casing 40 is formed of, for example, a resin such as PC (polycarbonate).

(Control unit 50)
The control unit 50 includes, for example, a central processing unit (CPU) that performs computations, processing, etc. on acquired data according to a stored program, a random access memory (RAM) as a semiconductor memory, a read only memory (ROM), and the like. Is a microcomputer that The ROM stores, for example, a program for the control unit 50 to operate and a load threshold. The RAM is used, for example, as a storage area for temporarily storing operation results and the like.

The control unit 50 is a load signal S _P output from the piezoelectric element 20 is configured to convert the load. Then, the control unit 50 compares the detected load with the load threshold to determine whether or not the pressing operation has been performed. When the pressing operation is determined, the control unit 50 outputs the operation information S _J indicating that the pressing operation has been performed, and outputs the driving signal _SD to drive the piezo element 20 downward to provide tactile sensation. Do.

(Operation at pressing operation)
As shown in FIG. 1B, when the panel 10 is pressed downward with a finger 100 with a load P, as shown in FIG. 3A, the piezo element 20, the metal shim 25, the flexible circuit board (FPC) 28 integrally deforms downward and bends. Thereby, the lower surface 25b of the metal shim 25 abuts on the bottom surface 43 of the groove 41, and the piezoelectric element 20 is restricted from any further deformation.

As shown in FIG. 1B, the piezoelectric element 20 is assembled by being preloaded regardless of the presence or absence of the pressing operation. This preloading the piezo element 20 (metal shim 25 as well), as shown in FIG. 3 (b), the displacement amount X ₁ is generated by preloading the piezoelectric element 20.

By the pressing force of the panel 10, (also metal shims 25) piezoelectric element 20 is deflected deformed downward, as shown in FIG. 3 (b), the pressing displacement X ₂ is generated.

In addition, when the load by the pressing operation exceeds the load threshold, the tactile sense is presented to notify the operator of the feeling of the pressing operation. To this end, the control unit 50 outputs the drive signal _SD to drive the piezo element 20 downward. Thus, as shown in FIG. 3 (b), the driving displacement X ₃ is displaced downward to generate.

The depth D of the groove 41, that is, the distance D from the contact surface 42a to the bottom surface 43, is the maximum allowable displacement X which is the sum of the displacement X ₁ , the pressure displacement X ₂ and the driving displacement X ₃ described above. It is set to be smaller than that. Thereby, the displacement amount of the piezoelectric element 20 and the metal shim 25 is limited by the depth D of the groove portion 41 in the pressing operation. Therefore, the displacement of the piezo element 20 is suppressed from exceeding the maximum allowable displacement amount X, the destruction due to the deformation of the piezo element 20 is suppressed, and the strength of the piezo element can be maintained. That is, in the first embodiment, since the groove 41 is configured to be shallower than the maximum allowable displacement of the piezoelectric element 20, the stopper structure can be configured as a groove. Thus, the stopper structure can be configured as a limiting portion that limits the transfer load for transferring the displacement of the panel 10 to the piezo element 20.

Second Embodiment
In the second embodiment, the above-described stopper structure is set such that the movable distance E between the panel 10 and the casing 40 is smaller than the maximum allowable displacement amount X of the piezoelectric element 20. is there. In the first embodiment, the movement amount associated with the deformation of the piezoelectric element 20 is restricted by the depth D of the groove 41. However, in the second embodiment, the movement amount associated with the deformation of the piezoelectric element 20 is the panel 10 The movable distance E with respect to the casing 40 is regulated. In the second embodiment, the stopper structure is configured as a limiting portion that limits the transmission load for transmitting the displacement of the panel 10 to the piezoelectric element 20. Hereinafter, portions different from the first embodiment will be described.

  As shown in FIG. 4A, a restricting member 60 is provided between the panel 10 and the casing 40. The limiting member 60 is made of, for example, resin, metal or the like. The upper end 60 a of the limiting member 60 is attached and fixed to the lower surface 10 c of the panel 10. The limiting member 60 is set such that the distance between the lower end 60 b and the limiting surface 40 a of the casing 40 is the movable distance E. The side surface 60 c of the limiting member 60 is slidably guided between the side wall 60 c and the inner wall 40 b of the casing 40.

As in the first embodiment, the maximum allowable displacement amount X of the piezoelectric element 20 is a displacement amount X ₁ due to the preload of the piezoelectric element 20, a pressure displacement amount X ₂ deformed by the pressing force of the panel 10, and is the sum of the driving displacement X ₃ is displaced downward by the voltage driving. The movable distance E shown above is set to be smaller than the maximum allowable displacement amount X shown above. The bottom surface 43 of the groove 41 is formed with a sufficient depth so that the piezo element 20 does not abut on the pressing operation.

  As shown in FIG. 4B, when the panel 10 is pressed downward with a finger 100 with a load P, the piezoelectric element 20, the metal shim 25 and the flexible circuit board (FPC) 28 are integrally deformed downward. It bends. The downward deformation is limited by the lower end 60 b of the limiting member 60 abutting on the limiting surface 40 a of the casing 40. As a result, the displacement amount of the piezoelectric element 20 is suppressed from exceeding the maximum allowable displacement amount X, the destruction due to the deformation of the piezoelectric element 20 is suppressed, and the strength of the piezoelectric element can be maintained.

Third Embodiment
In the third embodiment, the above-described stopper structure is set such that the movable distance between the transmission member 30 and the casing 40 is smaller than the maximum allowable displacement amount X of the piezoelectric element 20. is there. In the first embodiment, the movement amount associated with the deformation of the piezoelectric element 20 is restricted by the depth D of the groove 41. However, in the third embodiment, the movement amount associated with the deformation of the piezoelectric element 20 is transmitted to the transfer member 30. The movable distance F between the and the casing 40 is regulated. In the third embodiment, the stopper structure is configured as a limiting unit that limits the transmission load for transmitting the displacement of the transmission member 30 to the piezo element 20. Hereinafter, portions different from the first and second embodiments will be described.

  As shown to Fig.5 (a), the transmission member 30 has the center member 31 and the restriction | limiting part 32 which protruded to the inner wall part 40b of the casing 40, and is comprised. The central member 31 functions as a pusher that transmits the pressing force to the panel 10 to the piezoelectric element 20 as in the first embodiment.

  The limiting portion 32 is set such that the distance between the lower end portion 32 b and the limiting surface 40 a of the casing 40 is the movable distance F. Further, the side surface portion 32 c of the restricting portion 32 is slidably guided between the side surface portion 32 c and the inner wall portion 40 b of the casing 40.

As in the first embodiment, the maximum allowable displacement amount X of the piezoelectric element 20 is a displacement amount X ₁ due to the preload of the piezoelectric element 20, a pressure displacement amount X ₂ deformed by the pressing force of the panel 10, and is the sum of the driving displacement X ₃ is displaced downward by the voltage driving. The movable distance F shown above is set to be smaller than the maximum allowable displacement amount X shown above. The bottom surface 43 of the groove 41 is formed with a sufficient depth so that the piezo element 20 does not abut on the pressing operation.

  As shown in FIG. 5B, when the panel 10 is pressed downward with a finger 100 with a load P, the piezoelectric element 20, the metal shim 25 and the flexible circuit board (FPC) 28 are integrally deformed downward. It bends. The downward deformation is limited by the lower end 32 b of the limiting portion 32 abutting on the limiting surface 40 a of the casing 40. As a result, the displacement amount of the piezoelectric element 20 is suppressed from exceeding the maximum allowable displacement amount X, the destruction due to the deformation of the piezoelectric element 20 is suppressed, and the strength of the piezoelectric element can be maintained.

(Effect of the embodiment)
According to the embodiment of the present invention, the following effects are obtained.
(1) A switch device 1 according to an embodiment of the present invention includes a panel 10 which is pressed and operated, a piezoelectric element 20 which generates power when a load is applied by pressing operation, and which is displaced when power is applied, and A groove member 41 for accommodating the piezoelectric element 20 and the transmission member 30 connecting the panel 10 and the piezoelectric element 20 so as to transmit the displacement of 10 to the piezoelectric element 20, wherein the groove 41 allows displacement of the piezoelectric element 20. And the stopper structure for limiting the displacement of the piezoelectric element 20 so that the displacement of the piezoelectric element 20 does not exceed the maximum allowable displacement, and the panel 10 and the piezoelectric element 20 are connected to transmit the displacement of each other And the casing 40 having the groove 41 for accommodating the displacement of the piezoelectric element 20, and the displacement of the piezoelectric element 20 exceeds the maximum allowable displacement. Is configured with a stopper structure for restricting the displacement of the piezoelectric element 20, a so no. With this stopper structure, the displacement amount of the piezo element 20 does not exceed the maximum allowable displacement amount, so that the piezo element 20 is prevented from exceeding the breaking stress, and the breakage of the piezo element 20 can be suppressed. The strength can be maintained. Thereby, destruction of the piezoelectric element can be suppressed.
(2) In the first embodiment, the depth D of the groove 41 is set to be smaller than the maximum allowable displacement amount X of the piezo element 20. As a result, since the stopper structure for maintaining the strength is not separately provided, the tolerance on the load transfer path to the piezoelectric element can be reduced, and the design in which the transmission member and the piezoelectric element contact without gaps becomes easy It has an effect of.
(3) In the second and third embodiments, the displacement amount of the piezoelectric element 20 is the maximum allowable displacement amount X when the restriction member 60 or the restriction portion 32 of the transmission member 30 abuts on the restriction surface 40 a of the casing 40. Restrict to not exceed. Therefore, even if the load at the time of the pressing operation becomes excessive, the excessive load does not act on the piezoelectric element 20, and the damage to the piezoelectric element is limited.

  Although some embodiments of the present invention have been described above, these embodiments are merely examples and do not limit the invention according to the claims. Moreover, these novel embodiments can be implemented in other various forms, and various omissions, replacements, changes, and the like can be made without departing from the scope of the present invention. Further, not all combinations of the features described in the embodiments are essential to the means for solving the problems of the invention. Furthermore, these embodiments are included in the scope and subject matter of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

Reference Signs List 1 switch device 10 panel 10 a top surface 10 b area 10 c bottom surface 20 piezo element 20 a top surface 20 b bottom surface 25 metal shim 25 a top surface 25 b bottom surface 30 transmission Members 31 central member 32 limiting portion 32b lower end portion 32c side surface 40 casing 40a limiting surface 40b inner wall portion 41 groove portion 42 stepped portion 42a contact surface , 43: bottom surface, 50: control unit, 60: limiting member, 60a: upper end, 60b: lower end, 60c: side portion, 100: fingers, D: depth, E: movable distance, F: movable distance , P: load, S _D : drive signal, S _J : operation information, S _P : load signal, X: maximum allowable displacement, X ₁ : displacement, X ₂ : pressure displacement, X ₃ : drive displacement

Claims (6)

A panel operated by pressing;
A piezoelectric element that generates power when a load is applied by the pressing operation, and is displaced when power is applied;
A transmission member connecting the panel and the piezoelectric element so as to transmit the displacement of the panel to the piezoelectric element;
A casing for accommodating the piezoelectric element, the casing having a groove for permitting displacement of the piezoelectric element;
A stopper structure for limiting the displacement of the piezoelectric element so that the displacement of the piezoelectric element does not exceed the maximum allowable displacement;
A switch device comprising: The groove is configured to be shallower than the maximum allowable displacement of the piezoelectric element,
The switch device according to claim 1, wherein the stopper structure is the groove.   The switch device according to claim 1, wherein the stopper structure is a limiting portion that limits a transfer load for transferring the displacement of the panel to the piezoelectric element.   The switch device according to claim 3, wherein the restriction portion restricts the transmission load by restricting the movement of the transmission member.   The switch device according to claim 3, wherein the limiting unit limits the transmission load by limiting a displacement amount of the panel.   The switch device according to any one of claims 1 to 5, wherein the maximum allowable displacement amount is a sum of a displacement amount by preloading of the piezoelectric element, a pressing displacement amount of the panel, and a driving displacement amount of the piezoelectric element. .

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