Tactile sensation providing apparatus

Included are a panel (30), an actuator (50), and a conversion unit (60) that is engaged with the panel (30) and the actuator (50) and uses displacement of the actuator (50) to convert the displacement direction and the displacement amount of the actuator (50) into a different displacement direction and a different displacement amount so as to cause the panel (30) to slide.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Japanese Patent Application No. 2014-131473 filed Jun. 26, 2014, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

This disclosure relates to a tactile sensation providing apparatus.

BACKGROUND

JP 4875050 B2 (PTL 1), for example, discloses a technique for providing a realistic tactile sensation to a contacting object, such as a finger, on a touch panel or other such panel. The tactile sensation providing apparatus disclosed in PTL 1 uses the squeeze film effect that occurs between the panel and the contacting object by vibrating the panel in the thickness direction, thereby providing the operator with the sensation of having “pressed” something.

CITATION LIST

Patent Literature

SUMMARY

Technical Problem

In a known tactile sensation providing apparatus, however, there is room for improvement in the apparatus configuration, since the panel is vibrated in the thickness direction.

Therefore, it would be helpful to provide an improved tactile sensation providing apparatus.

Solution to Problem

To this end, a tactile sensation providing apparatus according to this disclosure includes:

a panel;

an actuator; and

a conversion unit engaged with the panel and the actuator and configured to use displacement of the actuator to convert a displacement direction and a displacement amount of the actuator into a different displacement direction and a different displacement amount so as to cause the panel to slide.

The conversion unit may include a rotary member configured to rotate by displacement of the actuator so as to cause the panel to slide.

The conversion unit may include a linear motion member that has an inclined face extending in a direction intersecting the displacement direction of the actuator and that moves linearly in the displacement direction of the actuator by displacement of the actuator, and the conversion unit may include a sliding member that slides along the inclined face by displacement of the linear motion member so as to cause the panel to slide.

The tactile sensation providing apparatus may further include a pressure unit configured to cause the panel to engage with and press against the conversion unit and to cause the conversion unit to engage with and press against the actuator.

The actuator may include a laminated piezoelectric element; and

the laminated piezoelectric element may be disposed so that the displacement direction intersects a slide direction of the panel in plan view of the panel.

Advantageous Effect

According to this disclosure, an improved tactile sensation providing apparatus can be provided.

DETAILED DESCRIPTION

The following describes embodiments with reference to the drawings.

FIG. 1is an external perspective view schematically illustrating the structure of a tactile sensation providing apparatus according to Embodiment 1 of this disclosure. This tactile sensation providing apparatus10may be implemented as a dedicated apparatus or may be implemented in an electronic device having other functions, such as a smartphone or other mobile phone, a portable music player, a laptop computer, a wristwatch, a tablet, a game device, or the like.

The tactile sensation providing apparatus10according to this embodiment includes a housing20having an approximately rectangular external shape. The housing20may be formed from metal, rigid plastic, or the like. In the housing20, a panel30is provided at a front plate21, and as illustrated by the partial cutout of the panel30inFIG. 1, a display40is held below the panel30.

The panel30is a touch panel that detects contact, a cover panel that protects the display40, or the like. The panel30is, for example, made from glass or a synthetic resin such as acrylic or the like. The panel30is, for example, formed to be rectangular. When the panel30is a touch panel, the panel30detects contact by a contacting object such as the operator's finger, a pen, a stylus pen, or the like. Any known detection system may be used in the touch panel, such as a capacitive system, a resistive film system, a surface acoustic wave system (or an ultrasonic wave system), an infrared system, an electromagnetic induction system, a load detection system, or the like. In the present embodiment, for the sake of explanation, the panel30is assumed to be a touch panel. In this case, the panel30and the display40may be configured integrally.

The panel30is supported by the housing20so as to be slidable in the longitudinal direction. Across the slide range, a region of the panel30excluding surrounding portions of the front face30a is exposed through an opening21a formed in the front plate21of the housing20. When the panel30and the display40are configured integrally, both are supported so as to be able to slide integrally.

The display40may, for example, be configured by a liquid crystal display, an organic EL display, an inorganic EL display, electronic paper, or the like. The display40displays images (pages), objects for input such as icons and push buttons, and the like of application software (referred to below simply as an “application”), such as a browser, electronic book, or the like.

FIG. 2is a plan view schematically illustrating an enlargement of the structure of a section with the front plate21of the housing20removed. Guide members22that position the long sides30band30cof the panel30and guide the sliding of the panel30are disposed in the housing20. InFIG. 2, an example is illustrated in which a total of four guide members22are disposed at the edges of the long sides30band30cof the panel30, but the number of guide members22is not limited to four. On each long side, three or more may be provided, or one elongated guide member may be provided.

On one short side30dof the panel30, an actuator50and a conversion unit60are provided in the housing20. The actuator50constitutes the driving source for sliding the panel30and is configured by, for example, a piezoelectric element51. The piezoelectric element51is formed by elements that, upon application of an electric signal (voltage), are displaced either by expansion and contraction or by bending in accordance with the electromechanical coupling coefficient of their constituent material. Ceramic or crystal elements, for example, may be used. The piezoelectric element51may be a unimorph, bimorph, or laminated piezoelectric element. Examples of a laminated piezoelectric element include a laminated bimorph element with layers of bimorph and a stack-type element configured with a laminated structure formed by a plurality of dielectric layers composed of, for example, lead zirconate titanate (PZT) and electrode layers disposed between the dielectric layers. Unimorph is displaced by expansion and contraction upon the application of an electric signal, bimorph is displaced by bending upon the application of an electric signal, and a stack-type laminated piezoelectric element is displaced by expansion and contraction along the lamination direction upon the application of an electric signal. In the present embodiment, the piezoelectric element51is a stack-type laminated piezoelectric element.

One end of the piezoelectric element51is fixed to an inner wall of the housing20, and the piezoelectric element51extends nearly in parallel with the short side30dof the panel30. Accordingly, the displacement direction of the piezoelectric element51and the slide direction of the panel30intersect in plan view of the panel30. In order to guide displacement of the piezoelectric element51, a pair of guide members23is disposed in the housing20so as to sandwich the piezoelectric element51.

The conversion unit60is disposed to engage with the short side30dof the panel30and with the end face of the other end of the piezoelectric element51. The conversion unit60uses displacement of the piezoelectric element51to convert the displacement direction and displacement amount thereof into a different displacement direction and a different displacement amount so as to cause the panel30to slide. In this embodiment, the conversion unit60includes a rotary member61. The rotary member61includes a latch61a that rotatably latches onto a fixed axle62, an abutment61babutted by the piezoelectric element51, and an abutment61cabutted by the short side30dof the panel30. The latch61a is shaped as a hook, and the abutments61band61care formed as projections.

A pressure unit170is disposed on the other short side30eof the panel30. InFIG. 2, the pressure unit170pushes the panel30to the right, causing the short side30dof the panel30to abut and press against the abutment61cof the rotary member61and causing the abutment61bof the rotary member61to abut and press against the piezoelectric element51. The pressure unit170may, for example, be configured by an elastic body such as buffer material, a spring, rubber, or the like.

InFIG. 2, when the piezoelectric element51is displaced upwards, the rotary member61rotates to the left, with a fixed axle62as a pivot point. As a result, the displacement direction of the piezoelectric element51is converted nearly 90° by the conversion unit60and is transmitted to the panel30, and the panel30slides to the left against the pressure applied by the pressure unit170.

With reference toFIG. 3, operation of the conversion unit60is now described.FIG. 3is an enlargement of the conversion unit60. InFIG. 3, the pivot point indicates the fixed axle62with which the latch61a of the rotary member61engages, the point of effort indicates the abutment61bof the rotary member61abutted by the piezoelectric element51, and the point of load indicates the abutment61cabutted by the short side30dof the panel30. When S is the input displacement amount and T is the input force input to the point of effort by displacement of the piezoelectric element51, D is the displacement amount and F is the generated force acting on the point of load, L1is the distance from the fixed axle62that is the pivot point to the point of effort, and L2is the distance from the pivot point to the point of load, then the displacement amount D and generated force F can be approximated as in Equations (1) and (2) below. Here, L1and L2are respectively sufficiently larger than S and D.
D=S×L2/L1  (1)
F=T×L1/L2  (2)

From Equations (1) and (2) above, by appropriately setting the positions of the point of effort and the point of load, i.e. the distances L1and L2, a displacement amount D and generated force F sufficient to provide a tactile sensation can be obtained. In general, with the laminated piezoelectric element51, the input force T is large, but the input displacement amount S is small. By contrast, the slide amount of the panel30that can provide a tactile sensation, i.e. the displacement amount D, is large as compared to the input displacement amount S, and the force causing the panel30to slide, i.e. the generated force F, is small as compared to the input force T. Accordingly, the laminated piezoelectric element51that is readily available can be used.

The angle formed between the displacement direction of the piezoelectric element51and the slide direction of the panel30, i.e. the conversion angle for the displacement direction of the piezoelectric element51, is not limited to being 90° and may be set to any value. A simple configuration may therefore be used.

As illustrated inFIG. 3, drag A (equal to T) due to the piezoelectric element51that is the force generator, drag B (equal to F) due to the panel30that is the target of displacement, and drag C (equal to (T2+F2)1/2) to balance out the drag A and drag B are produced in the rotary member61. In other words, upon determining the position of the fixed axle62so that the drag A and drag B are always produced, the position of the rotary member61is determined by the balance of the three effects A, B, and C. Accordingly, the rotary member61need not be held tightly against the fixed axle62, thereby increasing the degree of freedom for the shape of the rotary member61and making the conversion unit60easier to assemble. For example, instead of the shape inFIG. 3, the rotary member61may have the shapes illustrated inFIGS. 4A to 4C.

In the rotary member61illustrated inFIG. 4A, the latch61a is formed in the shape of a hook, and the abutments61band61care formed on the sides of a fan shape. The rotary member61illustrated inFIG. 4Boverall has a polygonal fan shape. At the peak of the fan shape, the latch61a is formed to have an opening with a greater diameter than the fixed axle62, and the abutments61band61care formed on the sides of the fan shape. The rotary member61illustrated inFIG. 4Coverall has an L shape. The inner angle of the L shape forms the latch61a, and the abutments61band61care formed on the outer sides.

By the drag A and drag B always acting on the rotary member61, the ratio L1:L2, i.e. the ratios D:S and T:F can be maintained nearly constant, even if friction occurs in the engaging section between the rotary member61and the fixed axle62. Accordingly, without being affected by wear, the panel30can be caused to slide stably over an extended period of time under initial conditions.

The tactile sensation providing apparatus10according to this embodiment detects contact or a press on the panel30by the contacting object, such as the operator's finger, pen, or stylus pen, and displaces the piezoelectric element51. As a result, the panel30is caused to slide, providing a tactile sensation as feedback to the operator.

FIG. 5is a functional block diagram illustrating the circuit structure of a section of the tactile sensation providing apparatus10inFIG. 1. The tactile sensation providing apparatus10includes a controller70, a memory71, a piezoelectric element driver72, and the above-described panel30, display40, and piezoelectric element51.

The controller70is a processor that, starting with the functional blocks of the tactile sensation providing apparatus10, controls and manages the measurement apparatus10overall. The controller70is configured by a processor such as a Central Processing Unit (CPU) that executes a program specifying control procedures. Such a program may, for example, be stored in the memory71, on an external storage medium, or the like.

The memory71is configured by a semiconductor memory or the like. The memory71stores a variety of information, programs for causing the tactile sensation providing apparatus10to operate, and the like and also functions as a working memory.

The piezoelectric element driver72generates an electric signal to apply to the piezoelectric element51based on a control signal from the controller70and applies the electric signal to the piezoelectric element51.

Under the control of the controller70, the display40displays images (pages), objects for input such as icons and push buttons, and the like of an application. The panel30detects contact by the contacting object to an object displayed on the display40. The output of the panel30is provided to the controller70, and the position of contact by the contacting object on the panel30is detected.

Upon detecting contact, based on the output of the panel30, by the contacting object on an object for input displayed on the display40, the controller70uses the piezoelectric element driver72to drive the piezoelectric element51with a predetermined driving pattern. The controller70may detect contact on the panel30, further detect that the pressing load on the panel30by the contacting object has reached a predetermined value, and then drive the piezoelectric element51. In this case, the pressing load on the panel30may, for example, be detected based on output of the panel30or may be detected by attaching a load sensor such as a piezoelectric element, strain sensor, or the like to the panel30. The panel30is caused to slide by driving of the piezoelectric element51, and the operator is provided with a tactile sensation of having operated the object for input.

The driving pattern of the piezoelectric element51may, for example, be stored in the memory71in accordance with the object for input for which contact by the contacting object is detected. For example, when providing a tactile sensation of having pushed a push button, a pulsed driving voltage of half of a cycle at a predetermined frequency may be applied to the piezoelectric element51for a driving pattern that slides the panel30once back and forth. Additionally, in accordance with the object for input, a driving voltage of multiple cycles at a predetermined frequency may be applied to the piezoelectric element51for a driving pattern that slides the panel30back and forth multiple times.

With the tactile sensation providing apparatus10according to this embodiment, a tactile sensation is provided by sliding the panel30. Hence, as compared to when the panel30is displaced in the thickness direction, for example restrictions on the dimensions of the apparatus in the thickness direction can be eased. Since the conversion unit60includes the rotary member61, as described with reference toFIG. 3, the laminated piezoelectric element51that is readily available can be used for a simple configuration. Since the rotary member61need not be held tightly against the fixed axle62, the degree of freedom for the shape of the rotary member61is increased, making the conversion unit60easier to assemble. Also, without being affected by wear of the engaging section between the rotary member61and the fixed axle62, the panel30can be caused to slide stably over an extended period of time under initial conditions.

By the pressure unit170, the panel30is abutted against the abutment61cof the rotary member61, and the abutment61bof the rotary member61is abutted against the piezoelectric element51, thereby allowing the panel30to slide smoothly due to the piezoelectric element51. The piezoelectric element51is disposed along the short sides of the panel30, i.e. so that the displacement direction of the piezoelectric element51and the slide direction of the panel30intersect in plan view of the panel30. Hence, the dimensions of the apparatus in the direction of the long sides of the panel30can be reduced, making the apparatus more compact.

FIG. 6is a plan view schematically illustrating the structure of a section of a tactile sensation providing apparatus according to Embodiment 2 of this disclosure.FIG. 6corresponds toFIG. 2. The tactile sensation providing apparatus11according to this embodiment differs from the tactile sensation providing apparatus10according to Embodiment 1 in the structure of the conversion unit60. Constituent elements that are the same as in Embodiment 1 are labeled with the same reference signs, and the portions that differ are described below.

InFIG. 6, the conversion unit60includes a linear motion member63and a sliding member64. The linear motion member63has a wedge shape that includes an inclined face63a extending in a direction that intersects the displacement direction of the piezoelectric element51, a side63bconnected to the piezoelectric element51, and a side63cthat slides along an inner wall of the housing20. The sliding member64has a triangular shape that includes a sliding face64athat slides along the inclined face63aof the linear motion member63, a side64bconnected to the short side30dof the panel30, and a side64cthat extends in the direction of the long sides of the panel30and slides along a guide member24provided in the housing20.

InFIG. 6, upon the piezoelectric element51being displaced upwards, the linear motion member63is guided by the housing20and is also displaced upwards integrally with the piezoelectric element51. Upon the linear motion member63being displaced upwards, the sliding member64slides along the inclined face63aof the linear motion member63as a result of the displacement and is displaced linearly to the left inFIG. 6along the guide member24. As a result, the displacement direction of the piezoelectric element51is converted nearly 90° by the conversion unit60and is transmitted to the panel30, and the panel30slides to the left against the pressure applied by the pressure unit170.

With reference toFIGS. 7A to 7C, operation of the conversion unit60is now described.FIG. 7Ais an enlargement of the conversion unit60,FIG. 7Bis an enlargement of the linear motion member63, andFIG. 7Cis an enlargement of the sliding member64. InFIG. 7A, S is the input displacement amount and T is the input force input to the point of effort of the linear motion member63by displacement of the piezoelectric element51, D is the displacement amount and F is the generated force received by the sliding member64(panel30) from the point of load of the linear motion member63, and θ is the angle of the inclined face63a relative to the displacement direction of the linear motion member63. In this case, the displacement amount D is represented by Equation (3) below.
D=S×tan θ  (3)

The frictional force is P1and the coefficient of friction is μ1between the linear motion member63and the housing20that acts as a guide, the frictional force is P2and the coefficient of friction is μ2between the linear motion member63and the sliding member64, the frictional force is P3and the coefficient of friction is μ3between the sliding member64and the guide member24, and the input force and generated force taking fiction into account are respectively T′ and F′. In this case, the frictional forces P1and P2act on the linear motion member63, as illustrated inFIG. 7B. These frictional forces P1and P2are represented by the following equations, where N′ is the resultant force of the input force T′ and the generated force F′ acting in the normal direction of the inclined face63a.
P1=μ1×F′
P2=μ2×N′μ2×T′/sin θ

Accordingly, the input force T in this case is as in Equation (4) below.

The frictional forces P2and P3act on the sliding member64, as illustrated inFIG. 7C. These frictional forces P2and P3are represented by the following equations.
P2=μ2×N′μ2×T′/sin θ
P3=μ3×T′

Accordingly, the generated force F in this case is as in Equation (5) below.

From Equations (4) and (5) above, the generated force F acting on the panel30due to the input force T by the piezoelectric element51is represented as Equation (6) below.
F=T×(cot θ−μ2−μ3)/(1+μ1 cot θ+μ2 cot θ)  (6)

When there is no friction, F=T×cot θ. Furthermore, letting all of the coefficients of friction be the same (μ) yields F=T×(cot θ−2μ)/(1+2μ cot θ).

According to this embodiment, from Equations (3) and (6) above, by appropriately setting the angle θ of the inclined face63arelative to the displacement direction of the linear motion member63, a displacement amount D and generated force F sufficient to provide a tactile sensation can be obtained. Accordingly, as in Embodiment 1, the laminated piezoelectric element51that is readily available can be used. Furthermore, the linear motion member63and the sliding member64are both displaced linearly, yielding a simpler configuration. The other effects are similar to those of Embodiment 1. The conversion angle for the displacement direction by the linear motion member63and the sliding member64is not limited to being 90° and may be set to any angle.

The present disclosure is not limited to the above embodiments, and a variety of modifications and changes are possible. For example, the actuator is not limited to a piezoelectric element and may be configured using a magnetostrictor, a shape-memory alloy, or the like. In Embodiment 2, the conversion unit60may be configured as illustrated inFIG. 8orFIG. 9.

In the conversion unit60illustrated inFIG. 8, the inclined face63aof the linear motion member63is formed as a curved surface, and the sliding face64aof the sliding member64is formed as a curved surface in accordance with the shape of the inclined face63a.By forming the inclined face63aof the linear motion member63as a curved surface in this way, the angle of a tangent to the point of load in contact with the sliding member64changes as a result of displacement of the linear motion member63. Therefore, the change in the displacement amount D and the generated force F can be made non-linear with respect to the input displacement.

Accordingly, for example by making the angle θ′ of the upper portion of the linear motion member63inFIG. 8smaller than the angle θ inFIG. 7A, then upon initial input of the input force T, the displacement of the sliding member64is small, but the load due to static friction of the friction force P2can be reduced, and from the start of kinetic friction onwards, displacement of the sliding member64can be increased. As a result, the panel30can be caused to slide more smoothly.

The conversion unit60illustrated inFIG. 9includes a plurality of bearings65between the linear motion member63and the housing20that acts as a guide, between the linear motion member63and the sliding member64, and between the sliding member64and the guide member24. The bearings65may be spherical or may be cylindrical. In this way, by loading bearings65into the portions where the frictional forces P1, P2, and P3are generated in Embodiment 2, the frictional forces can be reduced nearly to zero, allowing the panel30to be caused to slide more smoothly with a smaller input force T.

REFERENCE SIGNS LIST

10,11Tactile sensation providing apparatus

63Linear motion member