ELECTRICAL DEVICE AND METHOD FOR CONTROLLING VIBRATION

An electrical device includes a vibrator and a controller. When receiving an electrical signal, the vibrator vibrates a vibration target. The controller inputs a first electrical pulse to the vibrator. Pulse width of the first electrical pulse is a period of time from the input of the first electrical pulse to the vibrator until displacement of the vibration target becomes maximum. After inputting the first electrical pulse, the controller inputs a second electrical pulse to the vibrator in such a way as to offset the vibration of the vibration target.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Japanese Patent Application No. 2021-147097 filed in the Japan Patent Office on Sep. 9, 2021, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to an electrical device and a method for controlling vibration.

BACKGROUND OF INVENTION

Techniques for presenting tactile sensations to users are known. An input device described in Patent Literature 1 controls driving of a vibration unit in such a way as to vibrate an input unit at a constant frequency, in order to present a clicking feel to an object that is pressing the input unit.

CITATION LIST

Patent Literature

SUMMARY

In an embodiment of the present disclosure, an electrical device includes a vibrator and a controller. When receiving an electrical signal, the vibrator vibrates a vibration target. The controller inputs a first electrical pulse to the vibrator. Pulse width of the first electrical pulse is a period of time from the input of the first electrical pulse to the vibrator until displacement of the vibration target becomes maximum. After inputting the first electrical pulse, the controller inputs a second electrical pulse to the vibrator in such a way as to offset the vibration of the vibration target.

In another embodiment of the present disclosure, a method for controlling vibration includes inputting a first electrical pulse to a vibrator that, when receiving an electrical signal, vibrates a vibration target and inputting, after inputting the first electrical pulse, a second electrical pulse to the vibrator in such a way as to offset the vibration of the vibration target. Pulse width of the first electrical pulse is a period of time from the input of the first electrical pulse to the vibrator until displacement of the vibration target becomes maximum.

DESCRIPTION OF EMBODIMENTS

Conventional techniques can still be improved in terms of vibration control. According to the present disclosure, an electrical device and a method for controlling vibration with improved control of vibration can be provided.

In an embodiment of the present disclosure, the electrical device in the present disclosure will be described as a tactile sensation presentation apparatus. The electrical device in the present disclosure, however, is not limited to the tactile sensation presentation apparatus. The electrical device in the present disclosure may be any device.

The embodiment of the present disclosure will be described hereinafter with reference to the drawings. Among components illustrated in the following drawings, the same components will be given the same reference numerals.

FIG.1is a block diagram illustrating a schematic configuration of a tactile sensation presentation apparatus1according to the embodiment of the present disclosure. The tactile sensation presentation apparatus1presents a tactile sensation to a user by vibrating an operation surface (vibration target).

The tactile sensation presentation apparatus1may be configured as any device. In an example, the tactile sensation presentation apparatus1may be configured as a vehicle device such as an automotive navigation system or a switch of a steering wheel or a power window. In another example, the tactile sensation presentation apparatus1may be configured as a mobile phone, a smartphone, a tablet PC (personal computer), a laptop PC, or the like. In yet another example, the tactile sensation presentation apparatus1may be configured as a desktop PC, a home appliance, a factory automation (FA) device, a dedicated terminal, or one of various other electronic devices. The tactile sensation presentation apparatus1, however, is not limited to these.

The tactile sensation presentation apparatus1includes a display unit10, a contact detection unit11, a pressure detection unit12, a vibration unit13, a storage unit14, and a control unit15.

The display unit10displays any information. The display unit10displays, for example, operation objects. When the tactile sensation presentation apparatus1is configured as a smartphone, for example, the display unit10displays an operation object for telephone, mail, a browser, a camera, or the like. In another example, when the tactile sensation presentation apparatus1is configured as a vehicle device, the display unit10displays an operation object for navigation, audio, air conditioning, or the like.

The display unit10includes, for example, at least one display. The display may be an LCD (liquid crystal display), an organic EL (electroluminescence) display, or the like.

The contact detection unit11detects contact of objects with the operation surface of the tactile sensation presentation apparatus1. The operation surface is a touch surface31ainFIGS.2and3, which will be referred to later. The user uses the operation surface. The user uses the operation surface by touching the operation surface with an object such as one of his/her fingers or a stylus pen.

Any method may be employed as a detection method used by the contact detection unit11to detect contact of objects with the operation surface. Examples of the detection method used by the contact detection unit11include a capacitive method, a resistive method, a surface acoustic wave method (or an ultrasonic method), an infrared method, an electromagnetic induction method, and a load detection method.

The pressure detection unit12detects pressure on the operation surface of the tactile sensation presentation apparatus1. Pressure is caused on the operation surface when the user presses the operation surface with his/her finger, a stylus pen, or the like.

The pressure detection unit12includes, for example, an element that linearly reacts to pressure. The element that linearly reacts to pressure is, for example, a strain gauge sensor, a piezoelectric element, or the like whose physical or electrical property (e.g., strain, resistance, voltage, etc.) changes in response to pressure.

When an electrical signal is input, the vibration unit13vibrates the operation surface of the tactile sensation presentation apparatus1. The electrical signal input to the vibration unit13may be a voltage signal or a current signal. When the electrical signal is a voltage signal, the vibration unit13includes, for example, a piezoelectric element or the like. When the electrical signal is a current signal, the vibration unit13includes, for example, a magnetostrictive element, an electromagnetic actuator, a current-driven motor, or the like. The electromagnetic actuator is, for example, a solenoid, a voice coil, or the like. The current-driven motor is, for example, a servomotor, a stepping motor, or the like.

The storage unit14includes at least one semiconductor memory, at least one magnetic memory, at least one optical memory, or a combination of at least two of these. The semiconductor memory is, for example, a RAM (random-access memory), a ROM (read-only memory), or the like. The RAM is, for example, an SRAM (static random-access memory), a DRAM (dynamic random-access memory), or the like. The ROM is, for example, an EEPROM (electrically erasable programmable read-only memory) or the like. The storage unit14may function as a main storage device, an auxiliary storage device, or a cache memory. The storage unit14stores data used for operation of the tactile sensation presentation apparatus1and data obtained as a result of the operation of the tactile sensation presentation apparatus1. For example, the storage unit14stores system programs, application programs, built-in software, and the like.

The control unit15includes at least one processor, at least one dedicated circuit, or a combination of these. The processor is a general-purpose processor such as a CPU (central processing unit) or a GPU (graphics processing unit) or a dedicated processor specialized in a certain type of processing. The dedicated circuit is, for example, an FPGA (field-programmable gate array), an ASIC (application-specific integrated circuit), or the like. The control unit15performs processing relating to the operation of the tactile sensation presentation apparatus1while controlling components of the tactile sensation presentation apparatus1.

FIG.2is a key component cross-sectional view illustrating an example of an implementation structure of the tactile sensation presentation apparatus1illustrated inFIG.1.FIG.3is a key component plan view illustrating the example of the implementation structure of the tactile sensation presentation apparatus1illustrated inFIG.1. In the example illustrated inFIGS.2and3, the tactile sensation presentation apparatus1includes a housing20, first insulators21, an upper cover22, second insulators23, a display30, a touch sensor31, strain gauge sensors32, and piezoelectric elements33. InFIG.3, broken lines indicate positions of the first insulators21and the piezoelectric elements33.FIG.3illustrates a configuration from which the housing20, the upper cover22, and the second insulators23have been removed.

As illustrated inFIG.2, the housing20holds the display30inside thereof. The display30holds the touch sensor31via the first insulators21.

As illustrated inFIG.2, the housing20is provided with the upper cover22. The upper cover22covers an edge area of the touch sensor31. The edge area of the touch sensor31covered by the upper cover22is an area of the display30outside a display area30A illustrated inFIG.3. The second insulators23are located between the upper cover22and the touch sensor31.

The first insulators21include elastic members. As illustrated inFIG.3, the four first insulators21are located at four corners outside the display area30A of the display30.

The second insulators23include elastic members. As with, or similarly to, the four first insulators21illustrated inFIG.3, the four second insulators23are located at the four corners outside the display area30A of the display30.

As illustrated inFIG.3, the display30has a square shape. The display30includes the square display area30A. The display30and the display area30A, however, may have any shapes that suit specifications of the tactile sensation presentation apparatus1. The display unit10illustrated inFIG.1may include the display30.

As illustrated inFIG.3, the touch sensor31has a square shape. The touch sensor31, however, may have any shape that suits the specifications of the tactile sensation presentation apparatus1.

The touch sensor31includes a front surface member and a back surface member. The front surface member includes the touch surface31a.The front surface member is composed of, for example, a transparent film, glass, or the like. The back surface member is composed of, for example, glass, acrylic, or the like. As the touch sensor31, a touch sensor having a structure whose front surface member, when the touch surface31ais pressed, bends (distorts) by a minute amount in response to pressure is used. The contact detection unit11illustrated inFIG.1may include the touch sensor31.

As illustrated inFIG.2, the strain gauge sensors32are located on a front surface of the touch sensor31. The strain gauge sensors32are located near sides of the front surface of the square touch sensor31covered by the upper cover22. The strain gauge sensors32detect pressure applied to the touch sensor31. The strain gauge sensors32may be provided on the front surface of the touch sensor31by adhesion or the like. The pressure detection unit12illustrated inFIG.1may include four strain gauge sensors32.

As illustrated inFIG.2, the piezoelectric elements33are located on a back surface of the touch sensor31. The two piezoelectric elements33may be located near two opposite sides of the square touch sensor31. The piezoelectric elements33may be provided on the back surface of the touch sensor31by adhesion or the like. The vibration unit13illustrated inFIG.1may include two piezoelectric elements33. The piezoelectric elements33may be configured to vibrate the touch surface31ain a direction parallel to the touch surface31aor a direction intersecting with the touch surface31a. Vibration in the direction parallel to the touch surface31ais called “horizontal vibration”. Vibration in the direction intersecting with the touch surface31ais called “vertical vibration”.

Process for Presenting Tactile Sensation

A principle of a method for presenting a tactile sensation is described in Japanese Patent No. 4633167 of Patent Literature 1. As described in Patent Literature 1, a general pushbutton switch has load characteristics illustrated inFIG.4.

FIG.4is a diagram illustrating load characteristics of a general pushbutton switch. InFIG.4, a horizontal axis represents a stroke [mm] of the pushbutton switch. A vertical axis represents a load [N] on the pushbutton switch.

A load characteristic of the pushbutton switch during pushing is observed in a period from point A to point D. A period from point A to point B is a period where the load increases substantially in proportion to the stroke of the pushbutton switch after the pushing of the pushbutton switch starts. A period from point B to point C is a period where the load sharply decreases. In the period from point B to point C, the pushing of the pushbutton switch causes a convex-shaped elastic member such as a metal dome to buckle, resulting in a sudden decrease in the load. In a period from point C to point D, the load increases substantially in proportion to the stroke of the pushbutton switch. In the period from point C to point D, a contact of the switch closes, and the load increases substantially in proportion to the stroke of the pushbutton switch.

A load characteristic of the pushbutton switch during releasing is observed in a period from point D to point G. The load characteristic during releasing has some hysteresis, but follows opposite changes from the load characteristic during pushing. A period from point D to point E is a period where the load decreases substantially in proportion to the stroke of the pushbutton switch after the releasing of the pushbutton switch starts. In the period from point D to point E, the contact of the switch remains closed. A period from point E to point F is a period where the load sharply increases. In the period from point E to point F, the releasing of the pushbutton switch causes the elastic member to return from the buckling to a convex shape, resulting in a sudden increase in the load. As the period from point E to point F begins, the contact of the switch opens. A period from point F to point G is a period where the load decreases substantially in proportion to the stroke of the pushbutton switch. The period from point F to point G is a period from the return of the elastic member until the user removes his/her finger from the pushbutton switch.

As described in Patent Literature 1, when pushing the pushbutton switch, the user receives vibration stimulation for a short period of time, such as about one period, at point B illustrated inFIG.4. When releasing the pushbutton switch, the user receives vibration stimulation for a short period of time, such as about one period, at point F illustrated inFIG.4. That is, in order to present a clicking feel to the user, the operation surface of the tactile sensation presentation apparatus1vibrates to give vibration stimulation to the user for a short period of time, such as about one period, at points B and F illustrated inFIG.4. In other periods, the user voluntarily presses or releases an operation button displayed on the tactile sensation presentation apparatus1to stimulate the user's sense of pressure. With this configuration, a clicking feel can be presented to the user.

In the present embodiment, when the control unit15detects contact of an object with the operation surface using the contact detection unit11, the control unit15detects pressure on the operation surface using the pressure detection unit12. The control unit15then determines whether the pressure on the operation surface detected using the pressure detection unit12satisfies a set criterion. The set criterion may be set on the basis of a pushing load applied to a button switch or the like when the user uses the button switch or the like. For example, the set criterion may be set on the basis of pushing loads at points B and F illustrated inFIG.4.

If determining that pressure on the operation surface detected using the pressure detection unit12satisfies the set criterion, the control unit15inputs a first electrical pulse to the vibration unit13. Pulse width of the first electrical pulse is a period of time from the input of the first electrical pulse to the vibration unit13until displacement of the operating surface reaches its maximum value. By inputting the first electrical pulse to the vibration unit13, stronger vibration stimulation than when, for example, an electrical pulse having a pulse width different from that of the first electrical pulse is input to the vibration unit13can be given to the user.

The vibration unit13will be described hereinafter as being configured to vibrate the operation surface of the tactile sensation presentation apparatus1when a voltage signal is input as an electrical signal. In the following description, the control unit15inputs a voltage pulse to the vibration unit13as an electrical pulse. The vibration unit13, however, may be configured to vibrate the operation surface of the tactile sensation presentation apparatus1when a current signal is input as an electrical signal, instead. In this case, the control unit15may input a current pulse to the vibration unit13as an electrical pulse.

FIG.5is a diagram illustrating a first voltage pulse P1according to the embodiment of the present disclosure. InFIG.5, a horizontal axis represents time. A left vertical axis represents voltage input to the vibration unit13. A right vertical axis represents displacement of the operation surface of the tactile sensation presentation apparatus1. The displacement of the operation surface is, for example, displacement in a direction perpendicular to the operation surface.

The first voltage pulse P1has a pulse width W1. The pulse width W1is a period of time half as long as a natural period T1. The first voltage pulse P1has a height V1. V1denotes a positive voltage. The first voltage pulse P1has a rectangular shape.

The natural period T1is a natural period of a vibration system including the operation surface. When the vibration unit13forcibly vibrates the operation surface, for example, the operation surface vibrates freely with the natural period T1. The natural period T1is determined on the basis of structure of the vibration system including the operation surface, that is, for example, the structure of the tactile sensation presentation apparatus1.

The control unit15begins to input the first voltage pulse P1to the vibration unit13at a time t0. The control unit15stops inputting the first voltage pulse P1to the vibration unit13at a time t1. The time t1is a point in time when half the natural period T1has elapsed since the time t0.

When the first voltage pulse P1is input to the vibration unit13, the displacement of the operation surface changes as indicated by a vibration waveform WA1. A period of the vibration waveform WA1is the natural period T1. A maximum value of the vibration waveform WA1is D1. D1is a positive value. A minimum value of the vibration waveform WA1is −D1. −D1is a negative value. The vibration waveform WA1reaches the maximum value at the time t1.

Since the pulse width W1is a period of time half as long as the natural period T1, the pulse width W1is a period of time from the time t0to the time t1. That is, the pulse width W1is a period of time from the input of the first voltage pulse P1to the vibration unit13until the displacement of the operation surface reaches its maximum value.

By inputting the first voltage pulse P1to the vibration unit13, the driving of the vibration unit13stops when the vibration waveform WA1reaches the maximum value D1. Since the driving of the vibration unit13stops when the vibration waveform WA1reaches the maximum value D1, the vibration waveform WA1reaches the minimum value −D1. Since the vibration waveform WA1reaches the minimum value −D1, amplitude of the vibration waveform WA1becomes 2×D1[=D1−(−D1)]. With this configuration, stronger vibration stimulation than when a voltage pulse having a pulse width different from the pulse width W1is input to the vibration unit13, for example, can be given to the user. This effect can be described with reference toFIG.6.

FIG.6is a diagram obtained by decomposing the first voltage pulse P1illustrated inFIG.5. The first voltage pulse P1illustrated inFIG.5can be decomposed into a step input I1and a step input I2. A horizontal axis, a left vertical axis, and a right vertical axis inFIG.6are the same as those inFIG.5.

The step input I1rises to V1at the time t0. A time at which the step input I1rises corresponds to a time at which the first voltage pulse P1illustrated inFIG.5rises. When the step input I1is input to the vibration unit13, the displacement of the operation surface changes as indicated by a vibration waveform WA2. A phase of the vibration waveform WA2is determined on the basis of the time at which the step input I1rises. A period of the vibration waveform WA2is the natural period T1. A maximum value of the vibration waveform WA2is D1. A minimum value of the vibration waveform WA2is zero. Amplitude of the vibration waveform WA2is D1.

The step input I2falls to −V1at the time t1. A time at which the step input I2falls corresponds to a time at which the first voltage pulse P1illustrated inFIG.5falls. The time t1is a point in time at which half the natural period T1has elapsed since the time t0. When the step input I2is input to the vibration unit13, the displacement of the operation surface changes as indicated by the vibration waveform WA3. A phase of the vibration waveform WA3is determined on the basis of the time at which the step input I2falls. A period of the vibration waveform WA3is the natural period T1. A maximum value of the vibration waveform WA3is zero. A minimum value of the vibration waveform WA3is −D1. Amplitude of the vibration waveform WA3is D1.

The vibration waveform WA1illustrated inFIG.5is obtained by combining together the vibration waveform WA2, whose phase is determined on the basis of the step input I2, and the vibration waveform WA3, whose phase is determined on the basis of the step input I2.

Here, a period of time from the rise of the step input I1, that is, the time t0, to the fall of the step input I2, that is, the time t1, is half as long as the natural period T1. Since the period of time from the time t0to the time t1is half as long as the natural period T1, the vibration waveform WA2and the vibration waveform WA3become, after the time t1, different from each other by an amount of phase shift corresponding to half the natural period T1. With this configuration, the vibration waveform WA2and the vibration waveform WA3strengthen each other after the time t1. For example, a time at which the vibration waveform WA2reaches the maximum value D1and a time at which the vibration waveform WA3reaches its maximum value, namely zero, are the same. After the time t1, a time at which the vibration waveform WA2reaches its minimum value, namely zero, and a time at which the vibration waveform WA3reaches the minimum value −D1becomes the same. With this configuration, the amplitude of the vibration waveform WA1, which is the combination of the vibration waveform WA2and the vibration waveform WA3, becomes 2×D1after the time t1. That is, the amplitude of the vibration waveform WA1is twice as large as that of the vibration waveform WA2and the vibration waveform WA3, namely D1. Since the amplitude of the vibration waveform WA1is twice as large as that of the vibration waveform WA2and the vibration waveform WA3, strong vibration stimulation can be given to the user.

Strong vibration stimulation, therefore, can be given to the user when the control unit15inputs the first voltage pulse to the vibration unit13.

After inputting the first voltage pulse, the control unit15inputs a second voltage pulse to the vibration unit13as a second electrical pulse in such a way as to offset the vibration of the operation surface. By inputting the second voltage pulse to the vibration unit13, a period of time for which vibration stimulation is given to the user can be shortened compared to, for example, when the second voltage pulse is not input to the vibration unit13.

Polarity of the second voltage pulse may be the same as that of the first voltage pulse. The polarity of the second voltage pulse may be opposite that of the first voltage pulse. Polarity of a voltage pulse is, for example, a direction in which the voltage pulse changes, namely a positive voltage or a negative voltage.

When the polarity of the second voltage pulse is the same as that of the first voltage pulse, the control unit15may, as will be described with reference toFIG.7, input a composite pulse, which is a combination of the first voltage pulse and the second voltage pulse, to the vibration unit13.

FIG.7is a diagram illustrating an example of a composite pulse S1according to the embodiment of the present disclosure. A horizontal axis, a left vertical axis, and a right vertical axis inFIG.7are the same as those inFIG.5.

The composite pulse S1is a combination of the first voltage pulse P1and a second voltage pulse P2. The composite pulse S1is configured as a single pulse. The second voltage pulse P2has a pulse width W2. The pulse width W2is a period of time half as long as the natural period T1. Polarity of the second voltage pulse P2is the same as that of the first voltage pulse P1. The second voltage pulse P2has the height V1as with the first voltage pulse P1. The second voltage pulse P2has a rectangular shape. The shape of the second voltage pulse P2is the same as that of the first voltage pulse P1.

The composite pulse S1has a pulse width WS1. The pulse width WS1is a combination of the pulse width W1of the first voltage pulse P1and the pulse width W1of the second voltage pulse P2. The pulse width WS1is the same as the natural period T1. The composite pulse S1has the height V1. The composite pulse S1has a rectangular shape.

The control unit15begins to input the composite pulse S1to the vibration unit13at the time t0. The control unit15stops inputting the composite pulse S1to the vibration unit13at a time t2. The time t2is a point in time when a period of time as long as the natural period T1has elapsed since the time t0.

When the composite pulse S1is input to the vibration unit13, the displacement of the operation surface changes as indicated by a vibration waveform WA4. A maximum value of the vibration waveform WA4is D1. A minimum value of the vibration waveform WA4is zero.

Since the pulse width WS1is the same period of time as the natural period T1, the driving of the vibration unit13stops when displacement of the vibration waveform WA4becomes zero, namely at the time t2. Since the driving of the vibration unit13stops when the displacement of the vibration waveform WA4becomes zero, the displacement of the operation surface also stops when becoming zero. With this configuration, the period of time for which vibration stimulation is given to the user can be shortened to a period of time substantially equal to the natural period T1. This effect can also be described with reference toFIG.8.

FIG.8is a diagram obtained by decomposing the composite pulse S1illustrated inFIG.7. The composite pulse S1illustrated inFIG.7can be decomposed into the step input I1and a step input I3. A horizontal axis, a left vertical axis, and a right vertical axis inFIG.8are the same as those inFIG.5.

The step input I1is as described above with reference toFIG.6. When the step input I1is input to the vibration unit13, the displacement of the operation surface changes as indicated by the vibration waveform WA2as described above with reference toFIG.6.

The step input I3falls to −V1at the time t2. A time at which the step input I3falls corresponds to a time at which the composite pulse S1illustrated inFIG.7falls. When the step input I3is input to the vibration unit13, the displacement of the operation surface changes as indicated by a vibration waveform WA5. A phase of the vibration waveform WA5is determined on the basis of the time at which the step input I3falls. A period of the vibration waveform WA5is the natural period T1. A maximum value of the vibration waveform WA5is zero. A minimum value of the vibration waveform WA5is −D1. Amplitude of the vibration waveform WA5is D1.

The vibration waveform WA4illustrated inFIG.7is a combination of the vibration waveform WA2, whose phase is determined on the basis of the step input I1, and the vibration waveform WA5, whose phase is determined on the basis of the step input I3.

Here, a period of time from the rise of the step input I1, that is, the time to, to the fall of the step input I3, that is, the time t2, is equal to the natural period T1. Since the period of time from the time t0to the time t2is equal to the natural period T1, the vibration waveform WA2and the vibration waveform WA5become, after the time t2, different from each other by an amount of phase shift corresponding to the natural period T1. With this configuration, the vibration waveform WA2and the vibration waveform WA5cancel each other after the time t2. For example, a time at which the vibration waveform WA2reaches the maximum value D1and a time at which the vibration waveform WA5reaches the minimum value −D1are the same. Since the vibration waveform WA2and the vibration waveform WA5cancel each other after the time t2, amplitude of the vibration waveform WA4, which is the combination of the vibration waveform WA2and the vibration waveform WA5, converges to zero.

The period of time for which vibration stimulation is given to the user, therefore, can be shortened to about a period of time equal to the natural period T1when the control unit15inputs the composite pulse S1to the vibration unit13.

The composite pulse S1has been described herein as a combination of the first voltage pulse P1and the second voltage pulse P2as illustrated inFIG.7for the sake of description. Here, as illustrated inFIG.7, the composite pulse S1configured as a single pulse has a linear symmetrical shape with the time t1, at which the vibration waveform WA4reaches its maximum value, as an axis of symmetry in the graph including the axis representing time and the axis representing voltage input to the vibration unit13. That is, when a voltage pulse having a linear symmetrical shape with a time at which a vibration waveform indicating the displacement of the operation surface reaches its maximum value as an axis of symmetry is input to the vibration unit13, the effect produced in the present disclosure can be produced even if the voltage pulse is not a combination of two voltage pulses.

The shape of the composite pulse is not limited to a rectangular shape illustrated inFIG.7. The composite pulse may have any shape. When the pulse does not have a rectangular shape, the pulse width may be defined in any manner insofar as the pulse width is uniquely determined. For example, the pulse width may be defined as a period of time from a rising edge (or a falling edge) of the pulse to a falling edge (or a rising edge) of the pulse. A rising edge of a pulse is, for example, a time at which voltage of the pulse rises to half the height of the pulse. A falling edge of a pulse is, for example, is a time at which voltage of the pulse falls to half the height of the pulse.

As described with reference toFIG.9, the control unit15may input a sinusoidal composite pulse S2to the vibration unit13as another example of the composite pulse.

FIG.9is a diagram illustrating another example of the composite pulse according to the embodiment of the present disclosure. A horizontal axis, a left vertical axis, and a right vertical axis inFIG.9are the same as those inFIG.5.

The control unit15begins to input the composite pulse S2to the vibration unit13at the time t0. The control unit15stops inputting the composite pulse S2to the vibration unit13at a time t6. When the control unit15inputs the composite pulse S2to the vibration unit13, the displacement of the operation surface changes as indicated by a vibration waveform WA6. A maximum value of the vibration waveform WA6is D2. D2is a positive value.

The composite pulse S2has a sinusoidal shape. Height of the composite pulse S2is V1. Voltage of the composite pulse S2becomes V1at a time t4. A rising edge of the composite pulse S2comes at a time t3. A falling edge of the composite pulse S2comes at a time t5. Pulse width of the composite pulse S2is a period of time from the time t3to the time t5.

The composite pulse S2is a combination of the first voltage pulse and the second voltage pulse. Pulse width of the first voltage pulse, which is one of the pulses included in the composite pulse S2, is, as described above, a period of time from the input of the first voltage pulse to the vibration unit13until the displacement of the operation surface reaches its maximum value. The second voltage pulse, which is the other of the pulses included in the composite pulse S2, offsets the vibration of the operation surface caused by the first voltage pulse. By inputting the composite pulse S2to the vibration unit13, strong vibration stimulation can be given to the user while shortening the period of time for which the vibration stimulation is given to the user compared to, for example, when a pulse other than the composite pulse S2is input to the vibration unit13. This effect can also be described with reference toFIG.10.

FIG.10is a diagram obtained by decomposing the composite pulse S2illustrated inFIG.9. The composite pulse S2illustrated inFIG.9can be decomposed into a step input I4and a step input I5. A horizontal axis, a left vertical axis, and a right vertical axis inFIG.10are the same as those inFIG.5.

The step input I4begins to rise at the time t0. The step input I4reaches half V1at the time t3. The step input I4rises to V1at the time t4. The rise of the step input I4corresponds to the rise of the composite pulse S2illustrated inFIG.9. When the step input I4is input to the vibration unit13, the displacement of the operation surface changes as indicated by a vibration waveform WA7. A phase of the vibration waveform WA7is determined on the basis of the rise of the step input I4.

The step input I5begins to fall at the time t4. The step input I5reaches half −V1at the time t5. The step input I5falls to −V1at the time t6. The fall of the step input I5corresponds to the fall of the composite pulse S2illustrated inFIG.9. When the step input I5is input to the vibration unit13, the displacement of the operation surface changes as indicated by a vibration waveform WA8. A phase of the vibration waveform WA8is determined on the basis of the fall of the step input I5.

The vibration waveform WA6illustrated inFIG.9is a combination of the vibration waveform WA7, whose phase is determined on the basis of the step input I4, and the vibration waveform WA8, whose phase is determined on the basis of the step input I5.

Here, after the time t6, the vibration waveform WA7and the vibration waveform WA8cancel each other. For example, a time at which the vibration waveform WA7reaches the maximum value D2and a time at which the vibration waveform WA8reaches the minimum value −D2are the same. With this configuration, amplitude of the vibration waveform WA6, which is the combination of the vibration waveform WA7and the vibration waveform WA8, converges to zero after the time t6.

By inputting the composite pulse S2to the vibration unit13, too, strong vibration stimulation can be given to the user while shortening the period of time for which the vibration stimulation is given to the user as described above.

In yet another example of the composite pulse, the control unit15may input a composite pulse having a shape illustrated inFIG.11,12,13, or14to the vibration unit13. Horizontal axes, left vertical axes, and right vertical axes inFIGS.11to14are the same as those inFIG.5.

A composite pulse S3illustrated inFIG.11has a shape of a rectangle on a trapezoid. When the control unit15inputs the composite pulse S3to the vibration unit13, the displacement of the operation surface changes as indicated by a vibration waveform WA9.

A composite pulse S4illustrated inFIG.12has a trapezoidal shape. When the control unit15inputs the composite pulse S4to the vibration unit13, the displacement of the operation surface changes as indicated by a vibration waveform WA10.

A composite pulse S5illustrated inFIG.13has a shape of a trapezoid on a rectangle. When the control unit15inputs the composite pulse S5to the vibration unit13, the displacement of the operation surface changes as indicated by a vibration waveform WA11.

A composite pulse S6illustrated inFIG.14has a pseudo-rectangular shape. In other words, the composite pulse S6has a slightly collapsed rectangular shape. When the control unit15inputs the composite pulse S6to the vibration unit13, the displacement of the operation surface changes as indicated by a vibration waveform WA12.

A composite pulse may be employed when vibration attenuates in a vibration system including an operation surface. This example will be described with reference toFIGS.15and16.

FIG.15is a diagram illustrating a first voltage pulse P3in a configuration where vibration attenuates. A horizontal axis, a left vertical axis, and a right vertical axis inFIG.15are the same as those inFIG.5. A natural period of a vibration system including an operation surface in a configuration where vibration attenuates will also be referred to as a “natural period T2”.

Pulse width of the first voltage pulse P3is a period of time half as long as the natural period T2. Height of the first voltage pulse P3is V2. V2is a positive voltage. The first voltage pulse P3has a rectangular shape.

The control unit15begins to input the first voltage pulse P3to the vibration unit13at the time t0. The control unit15stops inputting the first voltage pulse P3to the vibration unit13at a time t7. The time t7is a point in time when half the natural period T2has elapsed since the time t0.

When the control unit15inputs the first voltage pulse P3to the vibration unit13, the displacement of the operation surface changes as indicated by vibration waveform WA13. In the configuration illustrated inFIG.15where vibration attenuates, amplitude of the vibration waveform WA13attenuates over time.

FIG.16is a diagram illustrating an example of a composite pulse employed for the configuration illustrated inFIG.15. A horizontal axis, a left vertical axis, and a right vertical axis inFIG.16are the same as those inFIG.5.

A composite pulse S7is a combination of the first voltage pulse P3and a second voltage pulse P4. The composite pulse S7is configured as a single pulse. The second voltage pulse P4has the same pulse width as that of the first voltage pulse P3. The second voltage pulse P4has the same height as that of the first voltage pulse P3. Polarity of the second voltage pulse P4is the same as that of the first voltage pulse P3.

Pulse width of the composite pulse S7is a period of time equal to the natural period T2. The composite pulse S7has a rectangular shape. The composite pulse S7, however, may have one of the shapes illustrated inFIGS.9,11,12,13, and14.

The control unit15begins to input the composite pulse S7to the vibration unit13at the time t0. The control unit15stops inputting the composite pulse S7to the vibration unit13at a time t8. The time t8is a point in time when a period of time equal to the natural period T2has elapsed since the time t0.

When the control unit15inputs the composite pulse S7to the vibration unit13, the displacement of the operation surface changes as indicated by a vibration waveform WA14. After the time t8, amplitude of the vibration waveform WA14gradually converges to zero. Even when the amplitude of the vibration waveform WA14gradually converges to zero, the amplitude of the vibration waveform WA14after the time t8is significantly small compared to a maximum value of the vibration waveform WA14from the time t0to the time t8. Since the amplitude of the vibration waveform WA14after the time t8is significantly small, it becomes unlikely for the user to feel vibration stimulation based on the vibration waveform WA14after the time t8. With the configuration illustrated inFIG.16, therefore, a tactile sensation can be presented to the user.

As will be described with reference toFIG.17, the control unit15may input, to the vibration unit13, a composite pulse obtained by superimposing a part of the first voltage pulse and a part of the second voltage pulse upon each other.

FIG.17is a diagram illustrating yet another example of the composite pulse according to the embodiment of the present disclosure. A horizontal axis, a left vertical axis, and a right vertical axis inFIG.17are the same as those inFIG.5.

A composite pulse S8is obtained by superimposing a part of the first voltage pulse P1and a part of the second voltage pulse P2illustrated inFIG.7upon each other. In the composite pulse S8, the first voltage pulse P1and the second voltage pulse P2are superimposed upon each other such that the pulse width W1of the first voltage pulse P1and the pulse width W2of the second voltage pulse P2overlap by an overlap width W3.

The composite pulse S8has a pulse width WS3. The pulse width WS3is smaller than a period of time equal to the natural period T2, since a part of the first voltage pulse P1and a part of the second voltage pulse P2are superimposed upon each other. The composite pulse S8has the height V1. The composite pulse S8has a rectangular shape. The composite pulse S8, however, may have one of the shapes illustrated inFIGS.9,11,12,13, and14.

The control unit15begins to input the composite pulse S8to the vibration unit13at the time t0. The control unit15stops inputting the composite pulse S8to the vibration unit13at a time t9. The time t9is a point in time when a period of time corresponding to the pulse width WS3has elapsed since the time t0.

When the control unit15inputs the composite pulse S8to the vibration unit13, the displacement of the operation surface changes as indicated by a vibration waveform WA15. A maximum value of a first wave of the vibration waveform WA15is D1. A maximum value of a second wave of the vibration waveform WA15is D3. D3is a positive value.

The overlap width W3may be appropriately set such that D3of the second wave of the vibration waveform WA15achieves a preset ratio with respect to the maximum value D1of the first wave. As the overlap width W3decreases, the ratio of D3to D1becomes lower. As the overlap width W3increases, the ratio of D3to D1becomes higher. The ratio of D3to D1is set in advance, for example, in a specification document of the tactile sensation presentation apparatus1or the like. When the ratio of D3to D1is 30%, for example, the overlap width W3is set to 8% of the pulse width W1.

When the composite pulse S8is input to the vibration unit13, amplitude of the vibration waveform WA15gradually converges to zero after the time t9. Even when the amplitude of the vibration waveform WA15gradually converges zero, the amplitude of the vibration waveform WA15after the time t9is significantly small compared to the maximum value D1. Since the amplitude of the vibration waveform WA15after the time t9is significantly small, a tactile sensation can be presented to the user with the configuration illustrated inFIG.17.

Here, if the second voltage pulse is input to the vibration unit13in such a way as to offset the vibration of the operation surface caused by the first voltage pulse, the first voltage pulse and the second voltage pulse need not be combined together. This example will be described hereinafter with reference toFIGS.18to20.

FIG.18is a diagram illustrating a first voltage pulse and a second voltage pulse according to another embodiment of the present disclosure. A horizontal axis, a left vertical axis, and a right vertical axis inFIG.18are the same as those inFIG.5.

A second voltage pulse P5has the pulse width W2as with the second voltage pulse P2illustrated inFIG.7. Polarity of the second voltage pulse P5is the same as that of the first voltage pulse P1. The second voltage pulse P5has the height V1as with the first voltage pulse P1. The second voltage pulse P5has a rectangular shape. The shape of the second voltage pulse P5may be the same as that of the first voltage pulse P1.

As described with reference toFIG.5, the control unit15inputs the first voltage pulse P1to the vibration unit13. After stopping inputting the first voltage pulse P1to the vibration unit13, the control unit15begins to input the second voltage pulse P5to the vibration unit13at a time t10. The control unit15stops inputting the second voltage pulse P5to the vibration unit13at a time t11.

When the control unit15inputs the first voltage pulse P1and the second voltage pulse P5to the vibration unit13, the displacement of the operation surface changes as indicated by a vibration waveform WA16. A maximum value of a first wave of the vibration waveform WA16is D1. A maximum value of a second wave of the vibration waveform WA16is D4. D4is a positive value.

The control unit15performs control such that a time TI1becomes longer than or equal to half the natural period T2. The time TI1is a period of time from the time t0, at which the input of the first voltage pulse P1to the vibration unit13starts, to the time t10, at which the input of the second voltage pulse P5to the vibration unit13starts.

The vibration waveform WA16decreases after the time t1until a period of time equal to the natural period T2has elapsed since the time t0. Since the time TI1is longer than or equal to half the natural period T2, the second voltage pulse P5is input to the vibration unit13when the vibration waveform WA16decreases. The second voltage pulse P5acts to attenuate the displacement of the operation surface. That is, the second voltage pulse P5offsets the vibration of the operation surface caused by the first voltage pulse P1. With this configuration, amplitude of the vibration waveform WA16gradually converges to zero after the time t11. Even when the amplitude of the vibration waveform WA16gradually converges to zero, the amplitude of the vibration waveform WA16after the time t11is significantly small compared to the maximum value D1. Since the amplitude of the vibration waveform WA16after the time t11is significantly small, a tactile sensation can be presented to the user with the configuration illustrated inFIG.18.

The time TI1, which is longer than or equal to half the natural period T2, may be appropriately set such that the maximum value D4of a second wave of the vibration waveform WA16achieves a preset ratio with respect to the maximum value D1of a first wave of the vibration waveform WA16. As the time TI1decreases, the ratio of D4to D1becomes lower. As the time TI1increases, the ratio of D4to D1becomes higher. The ratio of D4to D1is set in advance, for example, in the specification document of the tactile sensation presentation apparatus1or the like. When the ratio of D4to D1is 30%, for example, the time TI1is set to 108% of the pulse width W1.

As will be described with reference toFIG.19, the control unit15may input the second voltage pulse to the vibration unit13such that the first voltage pulse and the second voltage pulse become symmetrical to each other with a time at which the displacement of the operation surface changes from the maximum value to the minimum value or from the minimum value to the maximum value as an axis of symmetry.

FIG.19is a diagram illustrating a first voltage pulse and a second voltage pulse according to yet another embodiment of the present disclosure. A horizontal axis, a left vertical axis, and a right vertical axis inFIG.19are the same as those inFIG.5.

A second voltage pulse P6has the pulse width W2as with the second voltage pulse P2illustrated inFIG.7. Polarity of the second voltage pulse P6is the same as that of the first voltage pulse P1. The second voltage pulse P6has the height V1as with the first voltage pulse P1. The second voltage pulse P6has a rectangular shape. The shape of the second voltage pulse P6may be the same as that of the first voltage pulse P1.

As described above with reference toFIG.5, the control unit15inputs the first voltage pulse P1to the vibration unit13. After stopping inputting the first voltage pulse P1to the vibration unit13, the control unit15begins to input the second voltage pulse P6to the vibration unit13at a time t13. The control unit15stops inputting the second voltage pulse P5to the vibration unit13at a time t14.

When the control unit15inputs the first voltage pulse P1and the second voltage pulse P6to the vibration unit13, the displacement of the operation surface changes as indicated by a vibration waveform WA17. The vibration waveform WA17reaches the maximum value D1at the time t1. The vibration waveform WA17reaches the minimum value −D1at the time t9.

The control unit15inputs the second voltage pulse P6to the vibration unit13such that the first voltage pulse P1and the second voltage pulse P2become linearly symmetrical to each other with a time t12as an axis of symmetry in, for example, the graph illustrated inFIG.19including the axis representing time and the axis representing voltage input to the vibration unit13. The time t12is a time at which the displacement of the operation surface changes from the maximum value to the minimum value as indicated by the vibration waveform WA17. Since the first voltage pulse P1and the second voltage pulse P2are symmetrical to each other with the time t12as the axis of symmetry, a period of time from the time t1to the time t12and a period of time from the time t12to the time t13can become the same.

Since the first voltage pulse P1and the second voltage pulse P2become linearly symmetrical to each other with the time t12as the axis of symmetry, a maximum value of the vibration waveform WA17becomes D1, and a minimum value of the vibration waveform WA17becomes −D1. With this configuration, amplitude of the vibration waveform WA17is 2×D1[=D1−(−D1)], that is, twice as large as that of the vibration waveform WA2and the vibration waveform WA3illustrated inFIG.6, namely D1.

Since the first voltage pulse P1and the second voltage pulse P2become linearly symmetrically to each other with the vibration time t12as the axis of symmetry, the input of the second voltage pulse P6to the vibration unit13starts at the time t13. The vibration waveform WA17decreases for a certain period of time from the time t13. The second voltage pulse P6acts to attenuate the displacement of the operation surface. That is, from the time t13to the time t14, the second voltage pulse P6acts to attenuate the displacement of the operation surface and offsets the vibration of the operation surface caused by the first voltage pulse P1. With this configuration, the vibration waveform WA17converges to zero after the time t14.

The vibration waveform WA17, which has the amplitude 2×D1, thus converges to zero after the time t14. Since the control unit15inputs the first voltage pulse P1and the second voltage pulse P6to the vibration unit13, therefore, vibration stimulation given to the user can be increased, and a period of time for which the vibration stimulation is given to the user can be reduced to about twice as long as the natural period T1.

Here, the time t13is a point in time when 3/2 of the natural period T1has elapsed since the time t0, at which the input of the first voltage pulse P1to the vibration unit13starts. After the time t13, the control unit15may input the second voltage pulse P6to the vibration unit13. With this configuration, too, vibration stimulation given to the user can be increased, and a period of time for which the vibration stimulation is given to the user can be shortened.

With the configuration illustrated inFIG.19, the first voltage pulse P1, whose height is a positive voltage, is input to the vibration unit13. The control unit15, however, may input a first voltage pulse whose height is a negative voltage to the vibration unit13. When the first voltage pulse whose height is a negative voltage is input to the vibration unit13, the operation surface vibrates such that polarity of the displacement of the operation surface becomes opposite that of the displacement of the vibration waveform WA17. In this case, the control unit15inputs the second voltage pulse to the vibration unit13such that the first voltage pulse and the second voltage pulse become linearly symmetrical to each other with a time at which the displacement of the operation surface changes from a minimum value to a maximum value as an axis of symmetry. When the first voltage pulse whose height is a negative voltage is input to the vibration unit13, polarity of the second voltage pulse may be negative as with that of the first voltage pulse.

As will be described with reference toFIG.20, the control unit15may input the second voltage pulse to the vibration unit13such that the first voltage pulse and the second voltage pulse become point-symmetric to each other with a time at which the displacement of the operation surface becomes zero as a point of symmetry, instead.

FIG.20is a diagram illustrating a first voltage pulse and a second voltage pulse according to yet another embodiment of the present disclosure. A horizontal axis, a left vertical axis, and a right vertical axis inFIG.20are the same as those inFIG.5.

A second voltage pulse P7has a pulse width W2as with the second voltage pulse P2illustrated inFIG.7. Polarity of the second voltage pulse P7is opposite that of the first voltage pulse P1. The second voltage pulse P7has the height −V1. The second voltage pulse P7has a rectangular shape.

As described above with reference toFIG.5, the control unit15inputs the first voltage pulse P1to the vibration unit13. After stopping inputting the first voltage pulse P1to the vibration unit13, the control unit15begins to input the second voltage pulse P7to the vibration unit13at a time t16. The control unit15stops inputting the second voltage pulse P7to the vibration unit13at a time t17.

When the control unit15inputs the first voltage pulse P1and the second voltage pulse P7to the vibration unit13, the displacement of the operation surface changes as indicated by a vibration waveform WA18. The vibration waveform WA18reaches the maximum value D1at the time t1. The vibration waveform WA18becomes zero at a time t15. The vibration waveform WA18reaches the minimum value −D1at the time t16.

The control unit15inputs the second voltage pulse P6to the vibration unit13such that the first voltage pulse P1and the second voltage pulse P2become point-symmetric to each other with a point sp1as a point of symmetry in, for example, the graph illustrated inFIG.20including the axis representing time and the axis representing voltage input to the vibration unit13. The point sp1is a point in the graph including the axis representing time and the axis representing voltage input to the vibration unit13. The point sp1indicates a time at which the displacement of the operation surface becomes zero. The voltage input to the vibration unit13at the point sp1is zero. Since the first voltage pulse P1and the second voltage pulse P2become point-symmetric to each other with the point sp1as the point of symmetry, a period of time from the time t1to the time t15and a period of time from the time t15to the time t16can be the same. The polarity of the first voltage pulse P1and the polarity of the second voltage pulse P7become opposite.

Since the first voltage pulse P1and the second voltage pulse P2become point-symmetric to each other with the point sp1as the point of symmetry, the maximum value of the vibration waveform WA18becomes D1, and the minimum value of the vibration waveform WA18becomes −D1. With this configuration, amplitude of the vibration waveform WA18becomes 2×D1[=D1−(−D1)], that is, twice as large as that of the vibration waveform WA2and the vibration waveform WA3illustrated inFIG.6, namely D1.

Since the first voltage pulse P1and the second voltage pulse P2become point-symmetric to each other with the point sp1as the point of symmetry, the input of the second voltage pulse P7to the vibration unit13starts at the time t16. The vibration waveform WA18increases for a certain period of time from the time t16. The second voltage pulse P7acts to decrease the displacement of the operation surface. That is, the second voltage pulse P7acts to decrease the displacement of the operation surface from the time t16to the time t17and offsets the vibration of the operation surface caused by the first voltage pulse P1. With this configuration, the vibration waveform WA18converges to zero after the time t17.

The vibration waveform WA18, which has the amplitude 2×D1, thus converges to zero after the time t17. When the control unit15inputs the first voltage pulse P1and the second voltage pulse P7to the vibration unit13, therefore, vibration stimulation given to the user can be increased, and a period of time for which the vibration stimulation is given to the user can be shortened to about 3/2 of the natural period T1.

Here, the time t16is a point in time when a period of time equal to the natural period T1has elapsed since the time t0, at which the input of the first voltage pulse P1to the vibration unit13starts. The control unit15may input the second voltage pulse P7to the vibration unit13when the time t16has elapsed. With this configuration, too, vibration stimulation given to the user can be increased, and a period of time for which the vibration stimulation is given to the user can be shortened.

As illustrated inFIG.21, the control unit15may input a composite pulse S9to the vibration unit13, instead of inputting the first voltage pulse P1and the second voltage pulse P5, which are separate from each other, illustrated inFIG.18to the vibration unit13.

FIG.21is a diagram illustrating yet another example of the composite pulse according to the embodiment of the present disclosure. A horizontal axis, a left vertical axis, and a right vertical axis inFIG.21are the same as those inFIG.5.

A composite pulse S9is a combination of the first voltage pulse P1and a second voltage pulse P8. The composite pulse S9has a pulse width WS4. The pulse width WS4is a combination of the pulse width W1of the first voltage pulse P1and a pulse width W4of the second voltage pulse P8. The composite pulse S9has the height V1. The composite pulse S9has a rectangular shape. The composite pulse S9, however, may have one of the shapes illustrated inFIGS.9,11,12,13, and14.

The control unit15begins to input the composite pulse S9to the vibration unit13at the time t0. The control unit15stops inputting the composite pulse S9to the vibration unit13at a time t18. The time t18is a point in time when a period of time corresponding to the pulse width WS4has elapsed since the time t0.

When the control unit15inputs the composite pulse S9to the vibration unit13, the displacement of the operation surface changes as indicated by a vibration waveform WA19. A maximum value of a first wave surface of the vibration waveform WA19is D1. A maximum value of a second wave of the vibration waveform WA19is D5. D5is a positive value.

The pulse width WS4may be appropriately set such the maximum value D5of the second wave of the vibration waveform WA19achieves a preset ratio with respect to the maximum value D1of the first wave. As with, or similarly to, D4with respect to D1, the ratio of D5to D1is set in advance, for example, in the specification document of the tactile sensation presentation apparatus1or the like. When the ratio of D5to D1is 30%, for example, the pulse width WS4is set to 108% of the natural period T2.

When the composite pulse S9is input to the vibration unit13, amplitude of the vibration waveform WA19gradually converges to zero after the time t18. Even when the amplitude of the vibration waveform WA19gradually converges to zero, the amplitude of the vibration waveform WA19after the time t18is significantly small compared to the maximum value D1. Since the amplitude of the vibration waveform WA19after the time t18is significantly small, a tactile sensation can be presented to the user with the configuration illustrated inFIG.20.

FIG.22is a flowchart illustrating a procedure of a process for presenting a tactile sensation performed by the tactile sensation presentation apparatus1illustrated inFIG.1. The process corresponds to an example of a method for controlling vibration according to the present embodiment. The control unit15may start processing in step S1at any time. For example, the control unit15starts the processing in step S1when the tactile sensation presentation apparatus1is turned on.

The control unit15determines whether the contact detection unit11has detected contact of an object with the operation surface (step S1). If the control unit15determines that contact of an object with the operation surface has been detected (step S1: YES), the control unit15proceeds to processing in step S2. If the control unit15does not determine that contact of an object with the operation surface has been detected (step S1: NO), on the other hand, the control unit15performs the processing in step S1again.

In the processing in step S2, the control unit15determines whether pressure on the operation surface detected by the pressure detection unit12satisfies the set criterion. If determining that the pressure on the operation surface satisfies the set criterion (step S2: YES), the control unit15proceeds to processing in step S3. If not determining that the pressure on the operation surface satisfies the set criterion (step S2: NO), on the other hand, the control unit15performs the processing in step S2again.

In the processing in step S3, the control unit15inputs the first voltage pulse to the vibration unit13. After inputting the first voltage pulse, the control unit15inputs the second voltage pulse to the vibration unit13in such a way as to offset vibration of the operation surface (step S4). After completing the processing in step S4, the control unit15ends the process for presenting a tactile sensation. After ending the process for presenting a tactile sensation, the control unit15may perform the processing in step S1again at any time.

As described above, in the tactile sensation presentation apparatus1, the control unit15inputs the first voltage pulse to the vibration unit13. The pulse width of the first voltage pulse is a period of time from the input of the first voltage pulse to the vibration unit13until the displacement of the operation surface reaches its maximum value. By inputting the first voltage pulse to the vibration unit13, stronger vibration stimulation can be given to the user than when, for example, a voltage pulse having a pulse width different from that of the first voltage pulse is input to the vibration unit13. After inputting the first voltage pulse, the control unit15inputs the second voltage pulse to the vibration unit13in such a way as to offset vibration of the operation surface. By inputting the second voltage pulse to the vibration unit13, a period of time for which the vibration stimulation is given to the user can be shortened compared to when, for example, the second voltage pulse is not input to the vibration unit13. The tactile sensation presentation apparatus1can present a more realistic clicking feel to the user by giving strong vibration stimulation to the user while shortening a period of time for which the vibration stimulation is given to the user.

Here, as a method for shortening a period of time for which vibration stimulation is given to the user, a method is possible where a vibration attenuation member for attenuating vibration of a vibration target is provided for the tactile sensation presentation apparatus. If such a vibration attenuation member is provided for the tactile sensation presentation apparatus, however, the tactile sensation presentation apparatus might undesirably increase in size. Such a vibration attenuation member might also attenuate intended vibration of the vibration target. If the intended vibration is attenuated, it might become difficult to present a realistic clicking feel to the user. A vibration attenuation rate of the vibration attenuation member provided for the tactile sensation presentation apparatus, therefore, sometimes cannot be increased. If the vibration attenuation rate of the vibration attenuation member cannot be increased, a period of time for which vibration stimulation is given to the user might not be efficiently shortened.

With the tactile sensation presentation apparatus1according to the present embodiment, a period of time for which vibration stimulation is given to the user can be shortened by inputting the second voltage pulse to the vibration unit13, even if the above-described vibration attenuation member is not provided. Since the vibration attenuation member need not be provided for the tactile sensation presentation apparatus1, a possibility that the tactile sensation presentation apparatus1might increase in size can be reduced. By using the second voltage pulse, a period of time for which vibration stimulation is given to the user can be efficiently shortened than when the vibration attenuation member is used.

According to the present embodiment, therefore, the tactile sensation presentation apparatus1and the method for controlling vibration with improved control of vibration can be provided.

In the tactile sensation presentation apparatus1according to the present embodiment, the polarity of the second voltage pulse may be the same as that of the first voltage pulse. Since the polarity of the second voltage pulse is the same as that of the first voltage pulse, the second voltage pulse can be generated using a circuit or the like for generating the first voltage pulse. The tactile sensation presentation apparatus1, therefore, need not include a dedicated circuit or the like for generating the second voltage pulse. With this configuration, a more realistic clicking feel can be presented to the user with a simpler configuration.

In the tactile sensation presentation apparatus1according to the present embodiment, the control unit15may input a composite pulse, which is a combination of the first voltage pulse and the second voltage pulse, to the vibration unit13. With this configuration, a period of time for which vibration is given to the user can be shortened to a period of time substantially equal to the natural period T1.

In the tactile sensation presentation apparatus1according to the present embodiment, a composite pulse may be configured as a single pulse. When two voltage pulses are input to the vibration unit13, for example, a time at which a second voltage pulse is input to the vibration unit13might need to be adjusted in accordance with the displacement of the operation surface or the like. When a composite pulse is configured as a single pulse, however, a time at which a second voltage pulse is input to the vibration unit13need not be adjusted in accordance with the displacement of the operation surface or the like. With this configuration, a more realistic clicking feel can be presented to the user with a simpler configuration.

In the tactile sensation presentation apparatus1according to the present embodiment, the control unit15may input the second voltage pulse to the vibration unit13such that the first voltage pulse and the second voltage pulse become linearly symmetrical to each other with a time at which the displacement of the operation surface changes from the maximum value to the minimum value or from the minimum value to the maximum value as an axis of symmetry. With this configuration, as described above with reference toFIG.19, vibration stimulation given to the user can be increased while shortening a period of time for which the vibration stimulation is given to the user to about twice as long as the natural period T1.

In the tactile sensation presentation apparatus1according to the present embodiment, the control unit15may input the second voltage pulse to the vibration unit13such that the first voltage pulse and the second voltage pulse become point-symmetric to each other with a time at which the displacement of the operation surface becomes zero as a point of symmetry. With this configuration, as described above with reference toFIG.20, vibration stimulation given to the user can be increased while shortening a period of time for which vibration is given to the user to about 3/2 of the natural period T1.

The drawings for describing the embodiments of the present disclosure are schematic diagrams. Dimensions, ratios, and the like on the drawings do not necessarily match those in reality.

Although embodiments of the present disclosure have been described on the basis of the drawings and the examples, note that those skilled in the art can make various variations and alterations on the basis of the present disclosure. Note, therefore, that such the scope of the present disclosure also includes such variations and alterations. The function of each component, for example, may be rearranged without causing a logical contradiction, and a plurality of components or the like may be combined together or further divided.

All of the components described in the present disclosure and/or all of the disclosed methods or all of the steps in the process may be combined in any manner unless corresponding features are mutually exclusive. Each of the features described in the present disclosure can be replaced by an alternative feature that serves for the same, equivalent, or similar purpose, unless explicitly denied. Each of the disclosed features, therefore, is just an example of a comprehensive series of the same or equivalent features, unless explicitly denied.

The embodiments in the present disclosure are not limited to any specific configuration according to one of the above-described embodiments. The embodiments of the present disclosure can be expanded to all the novel features described in the present disclosure or a combination thereof, all the novel methods or the steps in the process described or a combination thereof.

For example, in the above-described embodiments, a composite pulse has been described as a combination of the first voltage pulse and the second voltage pulse for the sake of description. It should be understood, however, that, insofar as any composite pulse having the above-described features is input to the vibration unit13, the effects produced in the present disclosure can be produced without inputting a composite pulse that is a combination of the first voltage pulse and the second voltage pulse to the vibration unit13.

For example, the first voltage pulse and the second voltage pulse have rectangular shapes in the above-described embodiments. The first voltage pulse and the second voltage pulse, however, are not limited to rectangular shapes. For example, the first voltage pulse and the second voltage pulse may have a shape of triangular waves, half-sine waves, or Gaussian waves, or a combination of these.

For example, in the above-described embodiments, the first electrical pulse is the first voltage pulse, and the second electrical pulse is the second voltage pulse. The first electrical pulse, however, is not limited to the first voltage pulse. The second electrical pulse is not limited to the second voltage pulse. For example, when a current signal is employed as the electrical signal input to the vibration unit13, the first electrical pulse may be a first current pulse, and the second electrical pulse may be a second current pulse. In this case, polarity of the current pulses are, for example, a positive current or a negative current, whichever the current pulses change.

For example, in the above-described embodiments, the tactile sensation presentation apparatus1is configured such that, as illustrated inFIG.5, the displacement of the operation surface first changes in a positive direction when a positive voltage, such as V1, is input to the vibration unit13. The tactile sensation presentation apparatus1, however, may be configured such that the displacement of the operation surface first changes in a negative direction when a positive voltage is input to the vibration unit13.

For example, in the above-described embodiments, the electrical device in the present disclosure has been described as the tactile sensation presentation apparatus1. The electrical device in the present disclosure, however, is not limited to the tactile sensation presentation apparatus1. For example, the electrical device in the present disclosure may be an electrical device including an actuator that employs pneumatic, hydraulic, or steam pressure.

In the present disclosure, terms such as “first” and “second” are identifiers for distinguishing the corresponding components. The components distinguished with the terms such as “first” and “second” in the present disclosure may exchange the numbers thereof. For example, the first voltage pulse may exchange “first” for “second”, which are identifiers, with the second voltage pulse. The identifiers are simultaneously exchanged. Even after the exchange of the identifiers, the components are still distinguished from each other. Identifiers may be removed. Components from which identifiers have been removed are distinguished from each other by reference numerals. The identifiers such as “first” and “second” in the present disclosure are not intended to be used as a sole basis for interpretation of order of the components or presence of an identifier with a smaller number.

REFERENCE SIGNS