JP6318970B2 - Vibrating body and tactile presentation device - Google Patents

Description

  The present invention relates to a vibrator provided with a film that is deformed in a plane direction by applying a voltage, and a tactile sense presentation device using the vibrator.

  An example of a film that deforms in a plane direction when a voltage is applied is a piezoelectric film. As an example of a vibrating body provided with a piezoelectric film, for example, a flat speaker as disclosed in Patent Document 1 is known.

  The flat speaker of Patent Document 1 has a structure in which both ends of a diaphragm made of metal or the like are fixed to a film (an exciter film on which a piezoelectric film is attached). The diaphragm is fixed in a state where bending stress is generated by being fixed to the film in a curved state. When a drive signal is applied to the piezoelectric film, the piezoelectric film expands and contracts and the exciter film expands and contracts. The diaphragm vibrates in a direction (normal direction) perpendicular to the main surface by expansion and contraction of the exciter film. Such a flat speaker can be vibrated efficiently with respect to expansion and contraction of the piezoelectric film because bending stress is generated in the diaphragm.

  Patent Document 1 also shows an example in which a diaphragm of a flat speaker is fixed to a film in a flat state. For example, in FIG. 6 of Patent Document 1, a structure in which a diaphragm having a curved shape is prepared in advance and fixed to a film while applying a force to the diaphragm so that the diaphragm is flattened in a state where bending stress is generated. Have been described.

International Publication No. 2012/157691

  However, in the shape shown in FIG. 6 of Patent Document 1, when the piezoelectric film expands and contracts, the diaphragm is bent to the piezoelectric film side (recessed state) or is bent to the opposite side of the piezoelectric film ( Convex state) or unstable. Also, in order to change the diaphragm from a flat state to a convex state by pulling the end of the diaphragm due to the contraction of the piezoelectric film, a large tensile force is required, and a piezoelectric film having a very large piezoelectric constant is necessary. become.

  Accordingly, an object of the present invention is to provide a vibrating body capable of stably changing the bending direction of the diaphragm even with a film having a small displacement, and a tactile sense presentation device using the vibrating body.

  The vibrating body according to the present invention includes a diaphragm, a film whose main surface is connected to the diaphragm and is deformed in a plane direction by applying a voltage, a driving unit that applies a driving signal to the film, and the vibration Displacement means for displacing the diaphragm in the normal direction is provided on the main surface of the plate. And the vibrating body of this invention is characterized by the said displacement means displacing the said diaphragm in a normal line direction before the said drive part applies the said drive signal.

  Thus, the vibrating body of the present invention intends the diaphragm by the displacement means displacing the diaphragm in the normal direction before expanding and contracting the film that deforms in the plane direction by applying a voltage. It can be bent to a state (convex state). In particular, if the diaphragm is already bent into a convex state by the displacing means, the amount of bending can be changed without applying a large tensile force when the end of the diaphragm is pulled by contraction of the film. Therefore, even if the film has a small displacement with respect to the voltage, the bending direction of the diaphragm can be changed stably.

  Examples of the film that deforms in the plane direction when a voltage is applied include a piezoelectric film, an electrostrictive film, an electret film, a composite film, and an electroactive polymer film. Moreover, it is good also as an aspect which affixes the material (for example, piezoelectric film) which has piezoelectricity on the main surface of the resin film which does not have piezoelectricity, and connects the said resin film to a diaphragm.

  The displacement means may be any means as long as it can displace the diaphragm in the normal direction. For example, it is preferable to use a piezoelectric ceramic having a large piezoelectric constant. In particular, the displacement means only needs to apply a force that slightly deflects the diaphragm in a convex state, and the amount of subsequent bending can be changed by the tensile force of the film, so that the piezoelectric ceramic itself is made large. do not have to. Therefore, even when piezoelectric ceramics are used, the size of the piezoelectric ceramics itself can be reduced, so that the possibility of cracking of the ceramics is low.

  Moreover, it is preferable that the displacement means is attached between the diaphragm and the film. By attaching between the diaphragm and the film, the surface of the diaphragm opposite to the film can be made completely flat.

  The diaphragm is preferably fixed to the film in a state where bending stress is generated. In this case, the film is pulled toward the connection point with the diaphragm when the diaphragm is flat. Therefore, the diaphragm can be efficiently displaced with respect to the stretching of the film.

  In addition, a film and a displacement means can be bent uniformly in a surface direction by arranging a plurality.

  The vibrating body of the present invention can be used as a flat speaker, for example, but further includes a touch detection unit that detects a touch operation, and the drive unit detects when the touch detection unit detects the touch operation. In addition, it can be used as a tactile sense presentation device that transmits vibration to the user by applying a drive signal.

  According to this invention, even if it is a film with a small displacement, the bending direction of a diaphragm can be changed stably.

1 is an external perspective view of a tactile presentation device 10. FIG. 2 is a front view of the tactile sense presentation device 10. FIG. 1 is a side view of a tactile sense presentation device 10. 2 is a partially enlarged side view of the tactile sense presentation device 10. FIG. 1 is a block diagram illustrating a configuration of a tactile sense presentation device 10. FIG. 10 is an operation explanatory diagram of the tactile presentation device 10. It is a rear view of 10 A of tactile sense presentation apparatuses. It is a rear view of the tactile sense presentation device 10B. It is sectional drawing of the piezoelectric film which concerns on a modification.

  The vibrating body of the present invention constitutes a tactile sense presentation device as shown in FIG. FIG. 1 is an external perspective view of a tactile presentation device 10 according to the first embodiment. FIG. 2 is a front view of the tactile sense presentation device 10, and FIG. 3A is a side view.

  The tactile sense presentation device 10 includes a piezoelectric ceramic 20, a piezoelectric film 21, a diaphragm 40, a touch panel 50, and a frame 70. The tactile sense presentation device 10 is a so-called keyboard, and a flat touch panel 50 is provided with a plurality of touch sensors (touch detection units) 80 at positions corresponding to the key arrangement. The touch sensor 80 may be of any type as long as it has a function of detecting a user's touch operation, and various types such as a membrane type, a capacitance type, and a piezoelectric film type may be used.

  The touch panel 50 is attached to one main surface (front surface) of the flat diaphragm 40. The diaphragm 40 has a rectangular shape in plan view. Note that the touch panel 50 is not essential. For example, a plurality of touch sensors 80 may be provided on the front surface of the diaphragm 40 at positions corresponding to the key arrangement.

  The diaphragm 40 is fixed to the piezoelectric film 21 via frames 70 at both ends in the short direction on the other main surface (back surface). The main surface of the diaphragm 40 is fixed so as to be parallel to the main surface of the piezoelectric film 21 and is in a flat state. The back surface of the diaphragm 40 is fixed apart from the piezoelectric film 21. That is, a hollow region 100 is formed between the diaphragm 40 and the piezoelectric film 21. Piezoelectric ceramics 20 is mounted at a substantially central position on the back surface of diaphragm 40 in hollow region 100. The diaphragm 40 is made of, for example, acrylic resin (PMMA). The diaphragm 40 may be made of other materials such as a metal plate, PET, polycarbonate (PC), polylactic acid (PLA), and glass.

  As shown in FIG. 3B, the vibration plate 40 has a curved plate surface when not fixed to the piezoelectric film 21. Such a shape can be realized, for example, by bending a diaphragm having a flat main surface by heat treatment or the like.

  As shown in a white arrow St902 in FIG. 3B, the diaphragm 40 is applied with a bending force to both ends, and a frame 70 is formed so that a curved flat plate surface is flat as shown in FIG. 3A. It fixes to the piezoelectric film 21 via. The diaphragm 40 is fixed in a state where bending stress is generated by being fixed to the piezoelectric film 21 in such a state. Thereby, the piezoelectric film 21 is pulled by the tensile force S902 toward the frame 70 side by the elastic force F901 at the position of the frame 70. However, it is not an essential element in the present invention that the diaphragm is fixed in a state where bending stress is generated. The smaller the bending stress, the smaller the mechanical load at the vibration plate 40, the piezoelectric film 21, and the fixed position between the vibration plate 40 and the piezoelectric film 21.

  The piezoelectric film 21 is a film containing a piezoelectric resin. FIG. 4 is a partially enlarged side view of the tactile sense presentation device 10. As shown in FIG. 4, the piezoelectric film 21 includes a rectangular base film 200 in plan view, and electrodes 201 </ b> A and 201 </ b> B formed on both opposing main surfaces of the base film 200.

  The base film 200 is a piezoelectric resin, and for example, a material such as polyvinylidene fluoride (PVDF) or a chiral polymer is used. More preferably, polylactic acid (PLA) having high translucency is used. In particular, it is desirable to be made of PLLA. In the case of using PLA, the tactile sensation presentation device 10 having a high translucency in almost the entire front view can be realized by using a material having a high translucency in other configurations.

  When the base film 200 is composed of PLLA, as shown by the broken line arrows in FIG. 2, the outer periphery is cut so that the outer periphery is approximately 45 °, thereby forming a rectangular shape. Give piezoelectricity.

  The electrode 201 </ b> A and the electrode 201 </ b> B are formed on substantially the entire main surfaces of the base film 200. The electrode 201A and the electrode 201B are preferably composed mainly of indium tin oxide (ITO), zinc oxide (ZnO), and polythiophene. In addition, it is also possible to use a silver nanowire electrode for the electrode 201A and the electrode 201B, and it is preferable to use an aluminum vapor-deposited electrode as long as the light transmitting property may be low. A lead wiring conductor (not shown) is connected to the electrode 201A and the electrode 201B, and a drive signal is applied to the electrode 201A and the electrode 201B through the wiring conductor. The electrode 201 </ b> A disposed on the frame 70 side is attached to the frame 70 through the adhesive layer 60.

  In this example, the piezoelectric film 21 is connected to the diaphragm 40 via the frame 70, but the piezoelectric film is attached to another film and the other film is connected to the diaphragm 40 via the frame 70. It may be an embodiment. Examples of other films include polyethylene terephthalate (PET), polyethylene nanophthalate (PEN), polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC).

  As shown in FIG. 5, when the user touches the touch sensor 80 provided on the touch panel 50, first, a detection signal of the touch sensor 80 is input to the drive unit 81. The drive unit 81 applies a drive signal to the piezoelectric ceramic 20. The piezoelectric ceramic 20 expands and contracts according to the input drive signal. FIG. 6 is an operation explanatory diagram of the tactile sense presentation device 10, and FIG. 6A shows an initial state where the detection signal of the touch sensor 80 is not input.

  When the detection signal of the touch sensor 80 is input, the drive unit 81 applies an electric field in the first direction to the piezoelectric ceramic 20. That is, the drive unit 81 applies an electric field so that the piezoelectric ceramic 20 contracts along the plane direction as indicated by an arrow S911 in FIG. Since the piezoelectric ceramic 20 is mounted on the back surface of the diaphragm 40, the diaphragm 40 contracts on the back side as the piezoelectric ceramic 20 contracts. Therefore, the diaphragm 40 is displaced in the normal direction and is in a slightly bent state (convex state) on the front side.

  Then, as shown in FIG. 5, the drive unit 82 applies a drive signal to the piezoelectric film 21 after the drive unit 81 applies a drive signal to the piezoelectric ceramic 20, and applies an electric field in the first direction of the piezoelectric film 21. . That is, the drive unit 82 applies an electric field so that the piezoelectric film 21 contracts along the plane direction as indicated by an arrow S912 in FIG. Then, the diaphragm 40 is pulled in the center direction from the frame 70 side (end portion in the short side direction). Thereby, the diaphragm 40 is curved so as to protrude further forward as indicated by an arrow F911 in FIG.

  As described above, the tactile sense presentation device 10 is bent toward the back side when the piezoelectric film 21 is contracted by contracting the piezoelectric ceramic 20 to bend the diaphragm 40 in a convex state before the piezoelectric film 21 is contracted. It can be bent to a convex state stably without becoming a stagnation state (concave state). In particular, if the diaphragm 40 is already bent into a convex state by the piezoelectric ceramic 20, when the end of the diaphragm 40 is pulled by contraction of the piezoelectric film 21, the amount of bending is changed without applying a large tensile force. Therefore, even the piezoelectric film having a small piezoelectric constant can stably change the bending direction of the diaphragm 40.

  On the other hand, when the drive unit 82 applies an electric field in a second direction opposite to the first direction, the piezoelectric film 21 extends along the planar direction as indicated by an arrow S913 in FIG. As described above, a stationary bending stress is applied to the diaphragm 40 in a non-operating state, and the elastic force F901 is applied at the position of the frame 70. This elastic force F901 is in the same direction as the force applied to the diaphragm 40 by the extension of the piezoelectric film 21. Therefore, as shown by arrow F912 in FIG. 6D, diaphragm 40 is in a curved state (concave state) on the back side. Before the drive unit 82 applies the electric field in the second direction to the piezoelectric film 21, the drive unit 81 applies the electric field in the second direction to the piezoelectric ceramic 20 to bend the diaphragm 40 in the concave state. May be.

  As described above, the diaphragm 40 transitions to the state shown in FIG. 6C through the state shown in FIG. 6B when the piezoelectric film 21 contracts based on the state shown in FIG. When 21 is expanded, the state transitions to the state of FIG. The vibration generated thereby is transmitted to the touch panel 50 and transmitted to the user who touched the touch panel 50. Therefore, when the user touches the touch sensor 80 of the touch panel 50, the vibration is fed back, so that the user can feel that the key is “pressed”.

  Further, when a stationary bending stress is applied to the diaphragm 40 in a non-operating state, when the piezoelectric film 21 is stretched, the diaphragm 40 is efficiently transitioned to a concave state by the elastic force F901. Further, when the piezoelectric film 21 contracts, first, the piezoelectric ceramic 20 bends the diaphragm 40 in a convex state, so that the amount of bending of the piezoelectric film 21 can be changed without applying a large tensile force. Therefore, the tactile sense presentation device 10 can stably and efficiently change the bending direction of the vibration plate 40 and can transmit a strong vibration to some extent even when the piezoelectric film is used. In addition, the tactile sense presentation device 10 can be made thinner than vibration caused by a motor or the like.

  However, transition to the concave state of FIG. 6D is not essential in the present invention. For example, the state in which the diaphragm 40 is slightly bent into a convex shape as shown in FIG. 6B and the state in which the diaphragm 40 is greatly bent into a convex shape as shown in FIG. Can transmit vibration.

  In addition, it is desirable to fill the hollow region 100 with a soft resin such as silicone gel to suppress sound generated by vibration of the piezoelectric film 21 and the diaphragm 40.

  In the present embodiment, the piezoelectric ceramic 20 is shown as the displacing means of the present invention. However, any piezoelectric ceramic 20 may be used as long as the diaphragm 40 is displaced in the normal direction. For example, another piezoelectric film may be attached to the vibration plate 40. However, as the displacement means, it is only necessary to apply a force that slightly deflects the diaphragm 40 in a convex state, and the amount of subsequent deflection can be changed by the tensile force of the piezoelectric film 21, so that the displacement means itself There is no need to make it bigger. Therefore, even when piezoelectric ceramics are used as the displacing means, the size of the piezoelectric ceramics itself can be reduced, so that the possibility of cracking of the ceramics is low.

  Moreover, although the piezoelectric ceramic 20 showed the example attached to the back side (between the diaphragm 40 and the piezoelectric film 21) of the diaphragm 40, it may be attached to the front side and attached to both surfaces. Also good. However, by attaching between the diaphragm 40 and the piezoelectric film 21, the front side of the diaphragm 40 can be made completely flat.

  In the above example, when the user performs a touch operation, the driving unit 81 applies an electric field to the piezoelectric ceramic 20 to change the vibration plate 40 into a convex state. However, for example, when power is supplied The piezoelectric ceramic 21 may change the vibration plate 40 into a convex state, and when the user performs a touch operation, the driving unit 82 may apply an electric field to the piezoelectric film 21 to expand and contract the piezoelectric film 21. In other words, any aspect that falls within the normal direction of the piezoelectric ceramic 20 before the piezoelectric film 21 expands and contracts belongs to the technical scope of the present invention.

  In the above example, the example in which the piezoelectric ceramic 20 contracts along the plane direction is shown. However, the diaphragm 40 may be displaced in a convex state by extending in the normal direction.

  Next, a tactile sense presentation device according to a second embodiment will be described. FIG. 7 is a view of the tactile sense presentation device 10A according to the second embodiment as viewed from the back side. The tactile presentation device 10A is different from the tactile presentation device 10 according to the first embodiment in that the piezoelectric film 21 is divided into a plurality (two in this example) of piezoelectric films 21R and 21L. Different from the device 10. Other configurations are the same as those of the tactile sense presentation device 10.

  In this case, the piezoelectric film 21R and the piezoelectric film 21L can be individually driven. The number of piezoelectric films may be larger (for example, three).

  FIG. 8 is a view of the tactile sense presentation device 10B according to the third embodiment as viewed from the back side. The tactile presentation device 10B is different from the tactile presentation device 10 in that the piezoelectric film 21 is divided into three piezoelectric films 21R, a piezoelectric film 21L, and a piezoelectric film 21C. Moreover, it differs from the tactile sense presentation device 10 in that a plurality (two in this example) of the piezoelectric ceramics 20R and the piezoelectric ceramics 20L are provided. Other configurations are the same as those of the tactile sense presentation device 10.

  In this case, since the diaphragm 40 can be shifted to a convex state between the position where the piezoelectric ceramic 20R is attached and the position where the piezoelectric ceramic 20L is attached, the diaphragm 40 can be uniformly bent in the plane direction. .

  Next, FIG. 9A is a side view of a piezoelectric film 21 </ b> A according to a modification of the piezoelectric film 21. The piezoelectric film 21 illustrated in FIG. 4 has a structure in which one base film 200 is sandwiched between the electrode 201A and the electrode 201B. However, the piezoelectric film 21A illustrated in FIG. 9A has the base film 200, the electrode 201A, and the electrode 201B. A plurality of layers are stacked. In this example, electrodes 201 </ b> A and electrodes 201 </ b> B are alternately arranged with each base film 200 interposed therebetween. Thus, by laminating the plurality of base films 200, the electrodes 201A, and the electrodes 201B, the stretchability is further improved, and strong vibration can be generated.

  On the other hand, FIG. 9B is a side view of the piezoelectric film 21B according to the second modification. The piezoelectric film 21B shown in FIG. 10B realizes a laminated structure by sandwiching one base film 200 between the electrode 201A and the electrode 201B, and bending and stacking the base film 200, the electrode 201A, and the electrode 201B. It is. Also in this case, the stretchability is further improved, and a strong vibration can be generated. However, in this case, it is preferable to reinforce the electrical connection by applying a conductive paste or the like at a portion where the electrode is bent.

  In the present embodiment, a tactile sensation presentation device is shown as an example of the vibrator of the present invention. However, for example, it can be used as a flat speaker that vibrates a diaphragm according to an input audio signal.

  Moreover, in this embodiment, although the piezoelectric film was shown as an example, the "film which deform | transforms into a surface direction by applying a voltage" of this invention is not restricted to a piezoelectric film. Other examples of the film that deforms in the plane direction when a voltage is applied include an electrostrictive film, an electret film, a composite film, and an electroactive polymer film.

  The vibrating body of the present invention is a displacement means (for example, piezoelectric ceramic 20) that displaces the diaphragm 40 in the normal direction even when an electroactive film having a small electro-mechanical conversion constant or electro-displacement conversion constant is used. Therefore, the diaphragm can be bent to the intended state (convex state). The electroactive film is a film that generates stress by electrical driving or a film that generates displacement by deformation. Specifically, there are an electrostrictive film, a composite material (a material obtained by resin-molding piezoelectric ceramics), an electrically driven elastomer, or a liquid crystal elastomer.

  In the present embodiment, an example in which the piezoelectric film 21 is directly connected to the vibration plate 40 is shown. However, the piezoelectric film 21 is indirectly connected to the vibration plate 40 through another resin film that does not have piezoelectricity. It is good also as an aspect made. For example, the piezoelectric film 21 may be attached to the main surface of the resin film, and the end portion of the resin film may be connected to the diaphragm 40. Of course, in addition, a film such as an electrostrictive film, an electret film, a composite film, or an electroactive polymer film is attached to the main surface of the resin film, and the end of the resin film is connected to the diaphragm 40. It is also possible to adopt an aspect.

  The “film that deforms in the plane direction when a voltage is applied” can also be realized by using, for example, piezoelectric ceramics and a resin film. For example, it can be realized by connecting a plurality of resin films via piezoelectric ceramics and connecting each of the plurality of resin films to the diaphragm 40.

DESCRIPTION OF SYMBOLS 10 ... Tactile sense presentation apparatus 20 ... Piezoelectric ceramics 21 ... Piezoelectric film 40 ... Diaphragm 50 ... Touch panel 60 ... Adhesive layer 70 ... Frame 80 ... Touch sensor 81, 82 ... Drive part 100 ... Hollow area

Claims (6)

A diaphragm,
The diaphragm and the main surface are connected apart from each other, and a film that deforms in the surface direction by applying voltage;
A drive unit for applying a drive signal to the film;
Displacement means for displacing the diaphragm in a normal direction on the main surface of the diaphragm;
A vibrating body comprising
The vibrating body, wherein the displacing means displaces the diaphragm in a normal direction before the driving unit applies the driving signal.   The vibrating body according to claim 1, wherein the displacement unit is made of piezoelectric ceramics.   The vibrating body according to claim 1, wherein the displacement unit is attached between the diaphragm and the film.   The vibrating body according to claim 1, wherein the diaphragm is fixed to the film in a state where bending stress is generated.   The vibrating body according to claim 1, wherein the film and the displacement means are plural. A vibrating body according to any one of claims 1 to 5,
A touch detection unit for detecting a touch operation,
The drive unit is a haptic presentation device that applies the drive signal when the touch detection unit detects a touch operation.

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