Patent Description:
The present invention relates to a tactile sensation providing apparatus.

An actuator that generates vibration has been provided in a touch sensor or the like. The actuator is, for example, a unimorph. The actuator vibrates an object of vibration, such as a touch sensor, thereby providing a tactile sensation to a user who touches the object of vibration. For example, see patent literature PTL <NUM>. Vibration of the actuator is required to be transmitted efficiently to the object of vibration, and the actuator is required to be configured by a small number of components.

PTL <NUM> discloses a touch-sensitive input unit including a base, a touch-sensitive input surface for detecting a touch event thereon, the touch-sensitive input surface connected to and moveable relative to the base, and an actuating arrangement including an elastically deformable substrate between the touch-sensitive input surface and the base, and a piezoelectric patch transducer fixed to the substrate for controlling a bending force on the substrate to control a force on the touch-sensitive input surface by modulating a charge at the patch transducer.

PTL <NUM> discloses a piezoelectric actuator capable of providing high sound pressure and excellent frequency characteristics when it is used as an acoustic element and advantageous for a reduction in size. The piezoelectric actuator comprises a piezoelectric element performing such an expansion/contraction motion that its principal plane is expanded or contracted according to the state of a field, a pedestal on which the piezoelectric element is stamped, and four beam parts connected to the outer peripheral parts of the pedestal. The pedestal (vibrating part) is vertically vibrated according to the expansion/contraction motion of the piezoelectric element. Each of the beam parts comprises an extension part extending from the outer peripheral part of the pedestal to the outside and a rise part continuously extended from the extension part in a direction perpendicular to the extended direction of the extension part.

PTL <NUM> discloses a portable communications device having a function for sounding in the devices housed in cases, in which a piezoelectric sounding object element having the sounding function is provided through a foot part on the rear side of the cases. By providing the piezoelectric sounding object element with the foot part and mounting the element on the case or display part, the sounding characteristics of the piezoelectric sounding object element are improved. Further, the space can be effectively utilized and the costs can be reduced. Corresponding to the form or structure of the foot part, optimal acoustic characteristics can be provided. The piezoelectric sounding body element produced by another process beforehand is just fixed so that the portable communications device is suitable for mass-production.

The present invention provides a tactile sensation providing apparatus according to claim <NUM>.

The tactile sensation provided to a user by a tactile sensation providing apparatus can be determined in accordance with the magnitude of vibration of an object of vibration. For the object of vibration to vibrate greatly, the vibration generated by the actuator needs to be transmitted efficiently to the object of vibration while the vibration is increased.

For example, when a unimorph actuator is disposed on the object of vibration, a support member is provided to support the actuator against a housing or the like. To reduce attenuation of vibration of the actuator and to increase the transmission efficiency of vibration to the object of vibration, a component made of rubber or the like is sometimes used as the support member. The number of components increases when using a component made of rubber or the like. An increase in the number of components may lead to a decrease in reliability and may also lead to a rise in manufacturing costs.

An actuator described in conjunction with the present embodiment may be used in a variety of devices. A tactile sensation providing apparatus according to the present embodiment may be an on-vehicle device such as a car navigation system, a steering wheel, or a power window switch. The tactile sensation providing apparatus may also be a mobile phone, a smartphone, a tablet personal computer (PC), a notebook PC, or the like. The tactile sensation providing apparatus is not limited to these examples and may be any of a variety of electronic devices, such as a desktop PC, a household appliance, an industrial device or factory automation (FA) device, a dedicated terminal, or the like. The drawings referred to below are schematic illustrations. The dimensional ratios and the like in the drawings do not necessarily match the actual dimensions.

As illustrated in <FIG>, a tactile sensation providing apparatus <NUM> according to the present embodiment includes an actuator <NUM>, a housing <NUM>, and an object of vibration <NUM>.

The actuator <NUM> includes a piezoelectric element <NUM>, a vibration plate <NUM>, supports <NUM>, fixing portions <NUM>, and a holder <NUM>. The actuator <NUM> is joined to the housing <NUM> by the fixing portions <NUM>. The actuator <NUM> has the object of vibration <NUM> joined thereto via the holder <NUM>.

Each portion of the actuator <NUM> is described with reference to <FIG>, <FIG>.

The piezoelectric element <NUM> is, for example, rectangular. The piezoelectric element <NUM> expands and contracts in the longitudinal direction in a variety of patterns in accordance with an applied voltage signal. The piezoelectric element <NUM> may have a different shape. The piezoelectric element <NUM> may be a piezoelectric film or piezoelectric ceramic. Piezoelectric ceramic can generate vibration having a greater vibration energy than piezoelectric film can.

In an example not forming part of the invention, the piezoelectric element <NUM> may be replaced with a magnetostrictor. A magnetostrictor expands and contracts in accordance with the applied magnetic field. A magnetostrictor is used together with a coil or the like that converts an applied voltage signal to a magnetic field.

The vibration plate <NUM> is a rectangular plate-shaped member having a predetermined thickness. The vibration plate <NUM> may have a different shape. The vibration plate <NUM> is, for example, a thin plate with elasticity. The vibration plate <NUM> may, for example, be made of metal, resin, or a composite material of metal, resin, and the like. The vibration plate <NUM> may be a thin metal plate. A thin metal plate is also referred to as a shim. The surface facing the housing <NUM> is also referred to as a first main surface 12a. The surface facing the object of vibration <NUM> is also referred to as a second main surface 12b.

The piezoelectric element <NUM> is provided on the first main surface 12a of the vibration plate <NUM>. The piezoelectric element <NUM> is arranged so that the longitudinal direction of the piezoelectric element <NUM> matches the longitudinal direction of the vibration plate <NUM>. The holder <NUM> is provided on the second main surface 12b of the vibration plate <NUM>. The piezoelectric element <NUM> and the holder <NUM> are each joined to the vibration plate <NUM> by a method such as adhesion.

A structure in which the piezoelectric element <NUM> is provided on the first main surface 12a of the vibration plate <NUM> is known as a monomorph. In a monomorph, the expansion and contraction of the piezoelectric element <NUM> provokes bending vibration of the vibration plate <NUM>. When only one end of the vibration plate <NUM> is supported by the housing <NUM>, the vibration plate <NUM> vibrates with the amplitude in the normal direction of the first main surface 12a being maximized at the other end of the vibration plate <NUM>. When both ends of the vibration plate <NUM> are supported by the housing <NUM>, the vibration plate <NUM> vibrates with the amplitude in the normal direction of the first main surface 12a being maximized near the center of the vibration plate <NUM>.

A support <NUM> is provided at each end of the vibration plate <NUM> in the longitudinal direction. The supports <NUM> maintain a clearance between the piezoelectric element <NUM> and the housing <NUM> to prevent the piezoelectric element <NUM> from hitting the housing <NUM> when the vibration plate <NUM> vibrates in accordance with displacement of the piezoelectric element <NUM>. The supports <NUM> are, for example, thin plates with elasticity like the vibration plate <NUM>. The supports <NUM> may be made of the same or different material as the vibration plate <NUM>. When both ends of the vibration plate <NUM> are supported, the vibration plate <NUM> vibrates in accordance with displacement of the piezoelectric element <NUM>, with the amplitude being maximized near the center of the vibration plate <NUM>.

One end of each support <NUM> is connected to the vibration plate <NUM>. The other end of each support <NUM> is connected to one of the fixing portions <NUM>. The fixing portions <NUM> may, for example, be fixed to the housing <NUM> by screwing, adhesion, or the like. The fixing portions <NUM> may, for example, be thin plates with elasticity like the vibration plate <NUM>. The fixing portions <NUM> may be made of the same or different material as the vibration plate <NUM>.

In the actuator <NUM> described in conjunction with the present embodiment, the vibration plate <NUM>, the supports <NUM>, and the fixing portions <NUM> are integrally molded. The member in which the vibration plate <NUM>, the supports <NUM>, and the fixing portions <NUM> are integrally molded is also referred to below as a frame 10a of the actuator <NUM>. The frame 10a according to the present embodiment is entirely made of the same material. The frame 10a may, for example, be integrally molded by subjecting a thin sheet of metal to sheet-metal processing to bend the thin sheet. The frame 10a may be integrally molded by welding the vibration plate <NUM>, the supports <NUM>, and the fixing portions <NUM> together. The frame 10a may be made by integrally molding resin.

The holder <NUM> may, for example, be made of a rubber material. The holder <NUM> is not limited to a rubber material and may be made of another material, such as metal. The holder <NUM> is provided on the second main surface 12b side of the vibration plate <NUM>. The holder <NUM> is joined to the vibration plate <NUM> using a method such as adhesion. The holder <NUM> is provided near the center on the second main surface 12b side. The position at which the holder <NUM> is provided is not limited being near the center. The holder <NUM> may be provided at the portion where the amplitude of the vibration plate <NUM> is maximized. The holder <NUM> has the object of vibration <NUM> joined thereto by adhesion.

The holder <NUM> may have a large elastic modulus in the vibration direction of the vibration plate <NUM>, i.e. in the normal direction of the first main surface 12a, to efficiently transmit vibration of the vibration plate <NUM> to the object of vibration <NUM>. On the other hand, the holder <NUM> may have a small elastic modulus in a direction parallel to the first main surface 12a of the vibration plate <NUM>. This configuration can reduce the likelihood of damage to the tactile sensation providing apparatus <NUM> due to an external force. The elastic modulus is a constant indicating the relationship between an external force acting on a member and the amount of displacement of the member. The external force on the member corresponds to the product of the amount of displacement and the elastic modulus. In other words, the same external force produces a larger amount of displacement as the elastic modulus is smaller.

The housing <NUM> has the actuator <NUM> joined thereto by the fixing portions <NUM>. The housing <NUM> has a greater mass and a higher rigidity than the actuator <NUM> does. In the present embodiment, the housing <NUM> is considered to be a rigid body. The object of vibration <NUM> may, for example, be a touch sensor <NUM> provided in a device (see <FIG>) or a switch. The object of vibration <NUM> has the actuator <NUM> joined thereto by the holder <NUM>. When the housing <NUM> is considered to be a rigid body, the vibration generated by the actuator <NUM> is mainly transmitted to the object of vibration <NUM>. By the vibration being transmitted from the actuator <NUM> to the object of vibration <NUM>, the object of vibration <NUM> can provide a tactile sensation to the user that touches the object of vibration <NUM>.

As illustrated in <FIG>, the tactile sensation providing apparatus <NUM> further includes a controller <NUM>. The controller <NUM> may be constituted by a processor, microcomputer, or the like capable of executing application software. The controller <NUM> may appropriately include a storage unit or the like constituted by memory or the like capable of storing various information as necessary.

As illustrated in <FIG>, the controller <NUM> connects to the actuator <NUM>. The controller <NUM> outputs a drive signal to the actuator <NUM>. The drive signal may be a voltage signal that is applied to the piezoelectric element <NUM> of the actuator <NUM>.

The piezoelectric element <NUM> expands and contracts in the longitudinal direction in accordance with the drive signal acquired from the controller <NUM>. The vibration plate <NUM> of the example actuator <NUM> illustrated in <FIG>, <FIG> bends in accordance with displacement of the piezoelectric element <NUM>. When the piezoelectric element <NUM> is displaced by contracting in the longitudinal direction of the vibration plate <NUM>, the vibration plate <NUM> bends so that the second main surface 12b side becomes convex. When the piezoelectric element <NUM> is displaced by expanding in the longitudinal direction of the vibration plate <NUM>, the vibration plate <NUM> bends so that the first main surface 12a side becomes convex. Displacement of the piezoelectric element <NUM> is converted into vibration in the normal direction of the first main surface 12a of the vibration plate <NUM>.

In the present embodiment, the piezoelectric element <NUM> is displaced only in the contracting direction in response to application of a voltage signal. In this case, the vibration plate <NUM> oscillates between a state in which the second main surface 12b side is bent to become convex and a normal, straight state. The piezoelectric element <NUM> is not limited to being displaced in the contracting direction in response to application of a voltage signal. The piezoelectric element <NUM> may be configured to be displaced in the expanding direction in response to application of a voltage signal or to be displaced in both the expanding direction and the contracting direction.

In this way, the controller <NUM> drives the actuator <NUM> and vibrates the vibration plate <NUM>. Vibration of the vibration plate <NUM> is transmitted to the object of vibration <NUM> through the holder <NUM>. A tactile sensation is provided to the user touching the object of vibration <NUM> by vibration being transmitted to the object of vibration <NUM>.

As illustrated in <FIG>, for example, the controller <NUM> may connect to the touch sensor <NUM>. In this case, the controller <NUM> may output a drive signal to the actuator <NUM> in response to a signal acquired from the touch sensor <NUM>. The touch sensor <NUM> may be the object of vibration <NUM> of the tactile sensation providing apparatus <NUM>. In this case, a touch by the user on the object of vibration <NUM> is detected by the touch sensor <NUM>. The controller <NUM> vibrates the object of vibration <NUM> when the user is touching the object of vibration <NUM>. This configuration allows the tactile sensation providing apparatus <NUM> to provide a tactile sensation to the user touching the object of vibration <NUM>. The touch sensor <NUM> may be provided as a separate structure from the object of vibration <NUM> of the tactile sensation providing apparatus <NUM>.

The frame 10a of the actuator <NUM> elastically deforms in response to driving of the actuator <NUM>. When a voltage signal is not being applied to the piezoelectric element <NUM>, then the supports <NUM> are substantially upright relative to the fixing portions <NUM>, as illustrated in the example in <FIG>, <FIG>. In other words, when the piezoelectric element <NUM> is not expanding or contracting, the supports <NUM> are substantially upright relative to the fixing portions <NUM>. On the other hand, when the piezoelectric element <NUM> is displaced in the contracting direction, the vibration plate <NUM> bends so that the second main surface 12b side becomes convex, as illustrated in <FIG>. In accordance with the bending of the vibration plate <NUM>, the upper portions of the supports <NUM> are pulled by the vibration plate <NUM>. The lower portions of the supports <NUM> are fixed by the fixing portions <NUM>. Consequently, the supports <NUM> incline. As compared to the example frame 10a illustrated in <FIG>, <FIG>, the angles between the vibration plate <NUM> and the supports <NUM> and the angles between the supports <NUM> and the fixing portions <NUM> each increase.

As illustrated in <FIG>, the joint between the vibration plate <NUM> and the supports <NUM> and the joint between the supports <NUM> and the fixing portions <NUM> elastically deform so as not to obstruct vibration of the vibration plate <NUM>. The supports <NUM> may bend and function like leaf springs. As illustrated in <FIG>, the angles between the vibration plate <NUM> and the supports <NUM> and the angles between the supports <NUM> and the fixing portions <NUM> may be obtuse. As illustrated in <FIG>, the supports <NUM> may have a zig-zag cross-sectional shape.

The supports <NUM> may be configured to transmit the vibration of the vibration plate <NUM> to the object of vibration <NUM> through the holder <NUM> while absorbing as little of the vibration as possible. The supports <NUM> may be configured to have a larger elastic modulus in the vibration direction of the vibration plate <NUM> and a smaller elastic modulus in the expanding and contracting direction of the piezoelectric element <NUM>. The vibration direction of the vibration plate <NUM> corresponds to the normal direction of the first main surface 12a of the vibration plate <NUM>. The expanding and contracting direction of the piezoelectric element <NUM> corresponds to the longitudinal direction of the first main surface 12a of the vibration plate <NUM>. In other words, the supports <NUM> may be configured so that the ends of the vibration plate <NUM> are displaced more in the longitudinal direction than in the normal direction of the vibration plate <NUM> in accordance with expansion and contraction of the piezoelectric element <NUM>. When the supports <NUM> are configured for smaller displacement of the ends of the vibration plate <NUM> in the normal direction of the vibration plate <NUM>, the vibration of the vibration plate <NUM> is efficiently transmitted to the object of vibration <NUM>. When the supports <NUM> are configured for greater displacement of the ends of the vibration plate <NUM> in the longitudinal direction of the vibration plate <NUM>, attenuation of the vibration of the vibration plate <NUM> is reduced.

The vibration plate <NUM> and the supports <NUM> are integrally molded in the actuator <NUM> described in conjunction with the first embodiment. As compared to when the vibration plate <NUM> and the supports <NUM> are configured as separate components, the first embodiment allows a reduction in the number of components and assembly steps while the supports <NUM> reduce attenuation of the vibration of the vibration plate <NUM> generated in accordance with expansion and contraction of the piezoelectric element <NUM>. Furthermore, not using adhesive between the vibration plate <NUM> and the supports <NUM> lengthens the mean time between failure (MTBF) and improves the yield at the time of assembly.

In the first embodiment, the entire frame 10a of the actuator <NUM> is made of the same material. In the second embodiment, the vibration plate <NUM> and the supports <NUM> are made of different materials. The configuration example of a tactile sensation providing apparatus <NUM> according to the second embodiment illustrated in <FIG> has similarities to and differences from <FIG>. The differences from <FIG> are described below.

The vibration plate <NUM> of the present embodiment may, for example, be a thin plate with elasticity as in the first embodiment. The supports <NUM> are made of resin material. The resin material may, for example, be a rubber material such as silicone rubber or a sponge material such as hard sponge. As in the first embodiment, the supports <NUM> are configured to deform elastically so as to reduce attenuation of the vibration of the vibration plate <NUM>. The supports <NUM> are directly joined to the housing <NUM> by adhesion.

In the present embodiment, the vibration plate <NUM> and the supports <NUM> are integrally molded. For example, the vibration plate <NUM> and the supports <NUM> may be integrally molded by molding resin that becomes the supports <NUM> around a metal vibration plate <NUM>. The vibration plate <NUM> and the supports <NUM> may be integrally molded by engaging supports <NUM> made of resin with fitting portions provided in a metal vibration plate <NUM>. The vibration plate <NUM> and the supports <NUM> may be integrally molded by applying primer to a joining face provided on a surface of a metal vibration plate <NUM> and molding resin onto the joining face. The vibration plate <NUM> and the supports <NUM> may be integrally molded by performing microfabrication on a joining face provided on a surface of a metal vibration plate <NUM> and molding resin onto the joining face.

The vibration plate <NUM> and the supports <NUM> made of different materials are integrally molded in the actuator <NUM> described in conjunction with the second embodiment. As compared to when the vibration plate <NUM> and the supports <NUM> are configured as separate components, the second embodiment allows a reduction in the number of components and assembly steps while reducing attenuation of the vibration of the vibration plate <NUM> generated in accordance with displacement of the piezoelectric element <NUM>. Not using adhesive between the vibration plate <NUM> and the supports <NUM> can lengthen the MTBF and improve the yield at the time of assembly.

In the first and second embodiments, the actuator <NUM> may be configured without the fixing portions <NUM>. In this case, the ends of the supports <NUM> are joined to the housing <NUM> by adhesion. The ends of the supports <NUM> may be configured to be pivotable about the portion joined to the housing <NUM>.

The tactile sensation providing apparatus <NUM> and the actuator <NUM> of the present disclosure can reduce the number of components, improve reliability, and cut costs.

Claim 1:
A tactile sensation providing apparatus (<NUM>) comprising:
an actuator (<NUM>), a housing (<NUM>), and an object of vibration (<NUM>);
the actuator (<NUM>) comprising:
a piezoelectric element (<NUM>);
a vibration plate (<NUM>) that has the piezoelectric element (<NUM>) joined thereto on a first main surface (12a) of the vibration plate (<NUM>) and is configured to vibrate in accordance with displacement of the piezoelectric element (<NUM>);
supports (<NUM>) configured to support the vibration plate (<NUM>), respectively provided at the ends of the vibration plate (<NUM>) in a longitudinal direction, wherein the supports (<NUM>) maintain a clearance between the piezoelectric element (<NUM>) and the housing (<NUM>) to prevent the piezoelectric element (<NUM>) from hitting the housing (<NUM>) when the vibration plate (<NUM>) vibrates in accordance with displacement of the piezoelectric element (<NUM>); and
a holder (<NUM>) on a second main surface (12b) of the vibration plate (<NUM>),
wherein the object of vibration (<NUM>) is joined to the holder (<NUM>) by adhesion and configured to provide a tactile sensation to a user by vibration of the vibration plate (<NUM>) being transmitted to the object of vibration (<NUM>);
wherein the vibration plate (<NUM>) and the supports (<NUM>) are integrally molded;
wherein the first main surface (12a) of the vibration plate (<NUM>) is the surface facing the housing (<NUM>) and the second main surface (12b) of the vibration plate (<NUM>) is the surface facing the object of vibration (<NUM>); and
wherein the actuator (<NUM>) is joined to the housing (<NUM>) by fixing portions (<NUM>) or wherein the supports (<NUM>) are directly joined to the housing (<NUM>) by adhesion.