JP5710214B2 - Input device and control method of input device - Google Patents

Description

  The present invention relates to an input device including a touch sensor and a method for controlling the input device.

  In recent years, a mobile terminal such as a mobile phone, an information device such as a calculator and a ticket vending machine, a home appliance such as a microwave oven, a television, and a lighting fixture, an industrial device (FA device), etc. As input devices such as switches, input devices including touch sensors such as touch panels and touch switches are widely used.

  As such a touch sensor, various systems such as a resistive film system, a capacitance system, and an optical system are known. However, any type of touch sensor accepts a touch input by a finger or a stylus pen, and the touch sensor itself is not physically displaced like a push button switch even when touched.

  As described above, even if the touch sensor is touched, the touch sensor itself is not physically displaced, so that the operator cannot obtain feedback for the input even if the touch input is accepted. For this reason, the operator is likely to repeatedly input such as touching the same position many times, and may stress the operator.

  In order to prevent such repeated input, for example, a touch input is received and a sound is produced, or a display color of an input object such as an input button displayed on the display unit corresponding to the input position is displayed. There are known ones in which the input operation can be confirmed by hearing or vision by changing the display mode such as changing.

  However, in the case of a feedback method that works on hearing, it is difficult to confirm in a noisy environment, and if the device used is in a silent state such as manner mode, it cannot be handled. In the feedback method that works visually, if the size of the input object displayed on the display unit is small, especially in the case of finger input, the input object is hidden under the finger and the display mode changes. There are cases where it is not possible.

  Also, a feedback method has been proposed in which when the touch sensor accepts an input regardless of hearing or sight, the touch sensor is vibrated to generate a tactile sensation at the fingertip of the operator (for example, Patent Document 1). 2).

JP 2003-288158 A JP 2008-130055 A

  However, the techniques disclosed in Patent Documents 1 and 2 merely vibrate the touch sensor when the touch sensor receives an input. For this reason, especially when a button switch such as a push button switch (push-type button switch) is drawn on the top of the touch sensor, when the threshold value for accepting input from the touch sensor is low, a finger or the like touches the touch sensor lightly. A tactile sensation is presented just by touching. As a result, an erroneous operation is induced in response to an unintended operation (touch) before the operator pushes, or a sense of incongruity due to an unintended operation (touch) before the operator pushes is given. Here, the threshold value for accepting an input by touch of the touch sensor is a threshold value at which the touch sensor reacts. For example, in the resistive film method, the threshold value is a threshold value of the pressing force with which the upper conductive film contacts the lower conductive film. In the method, it is a detection threshold value of an electrical signal due to contact.

  In order to solve such inconvenience, the present applicant detects a pressing load on the touch surface of the touch sensor, and vibrates the finger when the detected load satisfies a predetermined standard for presenting a tactile sensation. When a push button switch such as a metal dome switch is pushed to the object to be pressed, an input device has been developed that presents a click sensation that can be felt when the metal dome is buckled.

  According to this input device, when the operator pushes the touch surface and the pressing load satisfies a predetermined standard, a click tactile sensation is presented, so that an erroneous operation due to the unintended touch described above is induced or a sense of incongruity is given. Thus, it is possible to reliably prevent the operator from recognizing that the input is accepted by the operator.

  By the way, in order to configure such an input device, in addition to the basic configuration of the touch sensor and its control unit, a load sensor that detects a pressing load on the touch sensor and an actuator that vibrates the touch sensor are required. For this reason, the number of parts increases and the cost is increased, and it is necessary to secure a space for installing the parts, resulting in an increase in the size of the apparatus.

  Therefore, in order to reduce costs and reduce the size of the apparatus, the present applicant uses the piezoelectric positive effect and the piezoelectric reverse effect of the piezoelectric element to detect the pressure load on the touch surface of the touch sensor. We have developed a device shared as an actuator that vibrates the sensor and the touch surface to present a tactile sensation to the object to be pressed.

  However, according to various experimental studies by the present applicant, it has been found that when the piezoelectric element is shared as a load sensor and an actuator, there are points to be improved as described below. That is, in this case, when the piezoelectric element is connected to the piezoelectric control circuit, the pressing load is detected based on the output voltage of the piezoelectric element by the piezoelectric control circuit, and the pressing load satisfies a predetermined criterion for presenting tactile sensation, A configuration in which a drive signal is supplied from the piezoelectric control circuit to the piezoelectric element to vibrate the piezoelectric element is assumed.

  For example, as shown in FIG. 8, at the time point P when the output voltage Vs of the piezoelectric element rises due to the pressing of the touch sensor by the object to be pressed and reaches a reference voltage Vref corresponding to a reference pressing load for presenting tactile sensation, A required drive signal Vd is applied to the element to drive the piezoelectric element. Thereby, when a push button switch such as a metal dome switch is pushed to the operator, a tactile sensation felt when the metal dome is buckled can be presented. FIG. 8 shows a case where one cycle of a sine wave having a predetermined frequency is applied as the drive signal Vd.

  However, in this case, the piezoelectric element vibrates in a loaded state, that is, under the pressure of the touch sensor by the pressing target. For this reason, the drive signal Vd that vibrates the piezoelectric element is larger than the output voltage Vs generated by the pressing by the pressing target, for example, 30 Vp-p. In addition, the drive signal Vd is applied in a state of being superimposed on the output voltage Vs (reference voltage Vref) in a state where the output voltage Vs of the piezoelectric element is at the reference voltage Vref. For this reason, depending on the piezoelectric element, the usable voltage range is exceeded, and the usable piezoelectric element is limited.

  As a countermeasure, a load detection unit that detects a pressing load based on the output voltage Vs of the piezoelectric element and a piezoelectric element driving unit that drives the piezoelectric element by a drive signal Vd are provided separately, and the load detection unit and the piezoelectric element are provided. A configuration is conceivable in which driving of the piezoelectric element is controlled by selectively connecting the driving unit to the piezoelectric element. Thus, for example, as shown in FIG. 9, the connection of the piezoelectric element is connected at the point P when the load detection unit detects that the output voltage Vs of the piezoelectric element has reached the reference voltage Vref that provides tactile sensation. The piezoelectric element drive unit can vibrate the piezoelectric element with the drive signal Vd to present a click feeling.

  However, according to further experimental studies by the present inventors, when the drive of the piezoelectric element is controlled by separating the load detection unit and the piezoelectric element drive unit as described above, the load detection unit detects the load after the piezoelectric element is driven. Actually, the output voltage Vs of the piezoelectric element does not change as shown in FIG. 9, and it depends on the influence of the drive signal Vd applied from the piezoelectric element drive unit immediately before the load detection is started or on the pressing target. It was found that it was affected by the load during pressing.

  For example, as shown in FIG. 9, after detecting that the output voltage Vs of the piezoelectric element has reached the reference voltage Vref and applying the drive signal Vd to the piezoelectric element to drive the piezoelectric element, the piezoelectric element is connected. When the tip is switched to the load detection unit and the output voltage Vs of the piezoelectric element is monitored, the output voltage Vs changes as shown in FIG. 10, for example. That is, when the output voltage Vs of the piezoelectric element increases to the positive polarity side when the touch sensor starts pressing, the output voltage Vs immediately after driving the piezoelectric element increases relatively sharply from 0 V to the negative polarity side, and thereafter It shows a behavior of gradually returning to 0 V due to spontaneous discharge of accumulated charges.

  Such a phenomenon is not limited to the case where a drive signal that presents a click sensation like a push button switch is applied as a drive signal, but a drive signal that presents a tactile sensation that can be perceived as vibration that is felt, for example, as a “bull”. It is presumed that the same is true in the case of doing so.

  For this reason, when the detection of the pressing load is started immediately after driving the piezoelectric element, for example, when the operator performs a strong pressing operation exceeding the reference voltage Vref until the residual charge of the piezoelectric element becomes approximately 0V. Unexpected tactile sensation is presented and the operator feels uncomfortable. In the case of FIG. 10, for example, a negative reference voltage Vref with respect to the positive reference voltage Vref may be set in the load detection unit, and detection of the pressing load may be started immediately after driving the piezoelectric element. . However, in this case, the piezoelectric element is driven at the time point Q when the output voltage Vs reaches the negative reference voltage Vref. As a result, the operator feels a click tactile sensation continuously for a short time, and presents a tactile sensation different from that of the push button switch, which gives a sense of incongruity.

  Depending on the drive signal applied to the piezoelectric element, the output voltage Vs after driving the piezoelectric element may be assumed to change from 0 V to the positive polarity side, contrary to the case of FIG. In this case, if the detection of the pressing load is started immediately after the piezoelectric element is driven, the output voltage Vs reaches the reference voltage Vref immediately after the piezoelectric element is driven, and the piezoelectric element is driven. As a result, the operator feels a click tactile sensation continuously in a short time, and similarly presents a tactile sensation different from that of the push button switch, giving a sense of incongruity.

  In this way, the piezoelectric element is shared as a load sensor and an actuator for tactile sensation, and the connection destination of the piezoelectric element is switched to the load detection unit or the piezoelectric element driving unit, so that the pressing load detection process and the piezoelectric element driving process are performed. When performing the above, the output voltage Vs after driving the piezoelectric element does not correspond to the pressing load actually pressed. For this reason, if the operation of detecting the pressing load by the load detection unit is started immediately after the driving of the piezoelectric element and the driving of the piezoelectric element is controlled, the operator may not be presented with a tactile sensation appropriately. Become.

  Accordingly, the object of the present invention made in view of the above points is to reduce the cost and reduce the size, and various piezoelectric elements can be used, and when the operator operates the touch sensor, the operator feels uncomfortable. It is an object of the present invention to provide an input device and an input device control method capable of appropriately presenting a tactile sensation without giving them.

The invention of the input device according to the first aspect to achieve the above object is as follows:
A touch sensor for detecting touch input;
One end of which is attached to the touch sensor, a piezoelectric element opposite other end of which is open,
A load detection unit that detects a pressing load on the touch surface of the touch sensor based on an output of the piezoelectric element, and determines whether the pressing load satisfies a criterion for presenting a tactile sensation;
A piezoelectric element driving unit that drives the piezoelectric element so as to present a tactile sensation with respect to a pressing target pressing the touch surface when the load detection unit determines that the reference is satisfied;
The load detector restarts detection of the pressing load after a predetermined time has elapsed after the piezoelectric element is driven by the piezoelectric element driver.
It is characterized by this.

The invention according to a second aspect is the input device according to the first aspect,
A discharge circuit for discharging the residual charge accumulated in the piezoelectric element;
The discharge circuit discharges residual charges accumulated in the piezoelectric element during the predetermined time;
It is characterized by this.

The invention according to a third aspect is the input device according to the first or second aspect,
The predetermined time is 40 ms or less;
It is characterized by this.

Furthermore, the invention of the control method of the input device according to the fourth aspect of achieving the above object is
A touch sensor for detecting touch input;
One end of which is attached to the touch sensor, a piezoelectric element opposite other end of which is open,
A load detection unit that detects a pressing load on the touch surface of the touch sensor based on an output of the piezoelectric element, and determines whether the pressing load satisfies a criterion for presenting a tactile sensation;
An input device comprising: a piezoelectric element driving unit that drives the piezoelectric element so as to present a tactile sensation to a pressing target pressing the touch surface when the load detection unit determines that the reference is satisfied. Control method,
The piezoelectric element is selectively connected to the load detection unit or the piezoelectric element driving unit,
In a state where the piezoelectric element is connected to the load detection unit, when it is determined that the load detection unit satisfies the reference, the connection of the piezoelectric element from the load detection unit to the piezoelectric element driving unit is switched, Driving the piezoelectric element by the piezoelectric element driving unit;
Next, after driving the piezoelectric element, switching the connection of the piezoelectric element from the piezoelectric element driving unit to the load detecting unit, and restarting detection of the pressing load by the load detecting unit after a predetermined time has elapsed. When,
It is characterized by including.

  The input device according to the present invention uses the piezoelectric element as a load sensor that detects a pressing load on the touch surface of the touch sensor and an actuator that vibrates the touch surface by using the piezoelectric positive effect and the piezoelectric reverse effect of the piezoelectric element. And sharing parts. As a result, the number of parts can be reduced and the cost can be reduced, and the installation space for the parts can be reduced and the apparatus can be downsized. In addition, since the load detection unit that detects the pressing load based on the output of the piezoelectric element and the piezoelectric element driving unit that drives the piezoelectric element are provided, the piezoelectric element is driven when the piezoelectric element is driven by the piezoelectric element driving unit. The piezoelectric element can be driven only by the drive signal without superimposing the drive signal on the output of the. As a result, the operating voltage range can be lowered, so that various piezoelectric elements can be used. In addition, after the piezoelectric element is driven, the load detection unit resumes the detection of the pressing load after a predetermined time has elapsed, so that it is possible to appropriately present the tactile sensation without causing the operator to feel uncomfortable.

It is a functional block diagram which shows schematic structure of the input device which concerns on 1st Embodiment of this invention. FIG. 2 is a circuit diagram illustrating a configuration of an example of a connection switching unit illustrated in FIG. 1. 2 is a timing chart illustrating a schematic operation of the input device illustrated in FIG. 1. FIG. 2 is a cross-sectional view and a main part plan view of an essential part showing an example of a mounting structure of an input device according to the present invention. It is a functional block diagram which shows schematic structure of the input device which concerns on 2nd Embodiment of this invention. 6 is a timing chart showing a schematic operation of the input device shown in FIG. 5. It is a timing chart explaining schematic operation | movement of the input device which concerns on 3rd Embodiment of this invention. It is a figure for demonstrating the subject of this invention. It is a figure for demonstrating the subject of this invention. It is a figure for demonstrating the subject of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a functional block diagram showing a schematic configuration of an input device according to the first embodiment of the present invention. The input device includes a touch sensor 11, a display unit 12, a piezoelectric element 13, a connection switching unit 14, a piezoelectric element driving unit 15, and a control unit 17 that controls the operation of each unit.

  The touch sensor 11 is connected to the control unit 17, and under the control of the control unit 17, detects a touch input by a pressing target such as a finger on the touch surface of the touch sensor 11, and obtains position information of the touch position. This is supplied to the control unit 17. The touch sensor 11 is configured by a known type such as a resistive film type, a capacitance type, and an optical type, and is disposed on the display unit 12.

  The display unit 12 is connected to the control unit 17 and displays an input object such as an input button such as a push button switch (push button switch) under the control of the control unit 17. The display unit 12 is configured using, for example, a liquid crystal display panel or an organic EL display panel. Touch input to the input object displayed on the display unit 12 is detected by the control unit 17 based on position information output from the touch sensor 11.

  The piezoelectric element 13 is attached to the touch sensor 11 so as to be bent (distorted) when the touch surface of the touch sensor 11 is pressed. The piezoelectric element 13 is connected to the connection switching unit 14 and selectively connected to the control unit 17 or the piezoelectric element driving unit 15 via the connection switching unit 14.

  The connection switching unit 14 selectively connects the piezoelectric element 13 to the control unit 17 or the piezoelectric element driving unit 15 according to a connection switching signal from the control unit 17. The piezoelectric element driving unit 15 includes a power amplifier or the like, and outputs a predetermined driving signal for vibrating the piezoelectric element 13 under the control of the control unit 17.

  The piezoelectric element 13 is connected to the control unit 17 via the connection switching unit 14, and supplies the control unit 17 with a voltage (output signal) due to charges generated by pressing the touch surface of the touch sensor 11. . The piezoelectric element 13 is driven by a drive signal supplied from the piezoelectric element driving unit 15 while being connected to the piezoelectric element driving unit 15 via the connection switching unit 14. Thereby, the touch sensor 11 vibrates and a tactile sensation is presented to the pressing target pressing the touch surface.

  The control unit 17 includes, for example, a CPU and the like, and includes a load detection unit 18 that detects a pressing load based on an output signal of the piezoelectric element 13 and determines whether or not the pressing load satisfies a criterion for presenting a tactile sensation. And the control part 17 controls operation | movement of each part based on the positional information from the touch sensor 11, the display information on the display part 12, the determination result by the load detection part 18, etc.

  FIG. 2 is a circuit diagram showing a configuration of an example of the connection switching unit 14 shown in FIG. The connection switching unit 14 is provided with two switch circuits 21 and 22 made of a semiconductor relay or the like, and an inverter 23. Each of the switch circuits 21 and 22 has an on / off contact, and the on / off contact of the switch circuit 21 is between the positive terminal of the piezoelectric element 13 and the output terminal (not shown) of the piezoelectric element driving unit 15. The on / off contact of the switch circuit 22 is connected between the positive terminal of the piezoelectric element 13 and the analog / digital conversion input terminal (not shown) of the control unit 17.

  The switch circuit 21 performs on / off control of the on / off contact via the inverter 23 by the connection switching signal a output from the control unit 17. Further, the switch circuit 22 performs on / off control of the on / off contact according to the connection switching signal a. Therefore, when one of the on / off contacts of the switch circuits 21 and 22 is in the on state, the other is in the off state.

  FIG. 3 is a timing chart showing a schematic operation of the input device according to the present embodiment. FIG. 3 shows the output signal (voltage) Vs and drive signal Vd of the piezoelectric element 13, the connection switching signal a, and the operating states of the load detector 18 and the piezoelectric element driver 15 with respect to the piezoelectric element 13. The control unit 17 always sets the connection switching signal a to the high (H) level. Thereby, the switch circuit 21 of the switching control unit 14 is turned off, the switch circuit 22 is turned on, and the piezoelectric element 13 is connected to the control unit 17.

In this state, the control unit 17 monitors the output of the touch sensor 11. Further, the load detection unit 18 of the control unit 17 detects a pressing load on the touch sensor 11 based on the output voltage Vs of the piezoelectric element 13, and whether or not the detected pressing load satisfies a criterion for presenting tactile sensation. Determine. Then, the control unit 17 inputs the position information from the touch sensor 11 to the input object displayed on the display unit 12, and the load detection unit 18 causes the output voltage Vs of the piezoelectric element 13 to be tactile. presentation criteria load (e.g., 1.5 N) when it is determined to reach the reference voltage Vref corresponding to, and connection switching the signal a predetermined time T ₁ low (L) level. As a result, the switch circuit 21 of the switching control unit 14 is turned on and the switch circuit 22 is turned off to connect the piezoelectric element 13 to the piezoelectric element driving unit 15.

  The control unit 17 drives the piezoelectric element 13 by outputting a predetermined drive signal Vd from the piezoelectric element driving unit 15 in a state where the piezoelectric element 13 is connected to the piezoelectric element driving unit 15. Thereby, the touch panel 11 is vibrated and a tactile sensation is presented to the pressing target pressing the touch surface. In addition, the control unit 17 performs predetermined processing on the input object in the display unit 12, for example, display mode change processing, display processing of a character corresponding to the input object in a predetermined display area, and application corresponding to the object. The execution process etc. are performed.

  Thereafter, when the driving of the piezoelectric element 13 by the piezoelectric element driving unit 15 is completed, the control unit 17 sets the connection switching signal a to H level, turns off the switch circuit 21 and returns the switch circuit 22 to on. As a result, the piezoelectric element 13 is disconnected from the piezoelectric element driving unit 15 and the piezoelectric element 13 is connected to the control unit 17.

Load detection unit 18, after the piezoelectric element 13 is driven until a predetermined time has elapsed, specifically, for example, connected switching signal a predetermined time T ₂ has elapsed from the switching unusual time to H level from L level Until this is done, the output voltage Vs from the piezoelectric element 13 is invalidated (cancelled). Thereafter, the load detection unit 18, from the time the predetermined time T ₂ has elapsed, the enable output voltage Vs of the piezoelectric element 13 and resumes the process of detecting the pressure load based on the output voltage Vs.

Here, the predetermined time T ₁ to the connection switching signal a and L level at time including the driving time of the piezoelectric element 13, fixed (e.g., about 10 ms) or set, or drive corresponding to tactile presenting It is automatically set according to the driving time by the signal. Further, after the driving of the piezoelectric element 13, the predetermined time T ₂ of the before resuming the process of detecting the pressure load in the load detection unit 18, after the driving of the piezoelectric element 13, the charge remaining in the piezoelectric element 13 is almost completely discharged Thus, the period is a period sufficient for the output voltage Vs to be approximately 0 V and a period that does not hinder the load detection of each input operation in a continuous input operation or the like. The predetermined time _{T 2} are, for example, 40ms or less.

  As described above, according to the input device according to the present embodiment, the load that detects the pressing load on the touch surface of the touch sensor 11 is detected by using the piezoelectric positive effect and the piezoelectric reverse effect of the piezoelectric element 13. The parts are shared by using the actuator that vibrates the sensor and the touch surface to present a tactile sensation to the object to be pressed. Therefore, since the number of parts can be reduced, the cost can be reduced and the installation space for the parts can be reduced, so that the apparatus can be downsized.

In addition, since the load detecting unit 18 and the piezoelectric element driving unit 15 are provided and the piezoelectric element 13 is selectively connected, the piezoelectric element driving unit 15 determines the output voltage Vs independently of the output voltage Vs of the piezoelectric element 13. A drive signal Vd can be supplied to the piezoelectric element 13. Therefore, since it is not necessary to apply a voltage obtained by adding the output voltage Vs and the drive signal Vd, the operating voltage range can be lowered, and various piezoelectric elements can be used. Moreover, after the piezoelectric element 13 is driven, that is, after the tactile sensation is first presented due to the increase of the pressing load due to the touch input, the detection of the pressing load by the load detecting unit 18 is resumed after the predetermined time T ₂ has elapsed. I have to. Therefore, during the predetermined time period T _2, since it exceeds the reference voltage Vref pressing force by the pressing target it becomes strongly feel not presented, without giving an uncomfortable feeling, such as the tactile sensation unexpected operator, Appropriate tactile sensation can be presented.

  Next, (1) a mounting structure, (2) a reference of a pressing load that presents a tactile sensation, and (3) a driving signal for driving the piezoelectric element 13 in the input device according to the present embodiment will be described.

(1) Mounting Structure FIG. 4 shows a schematic configuration of an example of the mounting structure of the touch sensor 11, the display unit 12, and the piezoelectric element 13 shown in FIG. 1, and FIG. 4 (b) is a plan view of the main part. The display unit 12 is housed and held in the housing 31. The touch sensor 11 is held on the display unit 12 via an insulator 32 made of an elastic member. In the present embodiment, the touch sensor 11 is held on the display unit 12 via the insulators 32 arranged at the four corners deviated from the display area A of the display unit 12 indicated by virtual lines in FIG. To do.

  Further, the housing 31 is provided with an upper cover 33 so as to cover the surface area of the touch sensor 11 deviated from the display area of the display unit 12, and is made of an elastic member between the upper cover 33 and the touch sensor 11. A dust-proof insulator 34 is provided.

  In the touch sensor 11 shown in FIG. 4, the surface member having the touch surface 11 a is made of, for example, a transparent film or glass, the back member is made of glass or acrylic, and the touch surface 11 a is pressed via the insulator 34. Then, a structure is used in which the pressing portion is bent (distorted) by a small amount in accordance with the pressing force, and the entire touch sensor 11 including the back member is bent by a small amount.

  The touch sensor 11 detects a pressing load on the touch surface 11a of the touch sensor 11 in the vicinity of one side or a plurality of sides covered with the upper cover 33, in this case, in the vicinity of the three sides on the back surface thereof. Are respectively attached to the piezoelectric elements 13 for presenting a tactile sensation to the pressing target pressing the touch surface 11a. In FIG. 4B, the casing 31, the upper cover 33, and the insulator 34 shown in FIG. 4A are not shown.

  Here, the three piezoelectric elements 13 are connected to the piezoelectric element driving unit via the connection switching unit and are driven by a common driving signal or driven by independent driving signals. In addition, the outputs of the three piezoelectric elements 13 are supplied in parallel to the load detection unit via the connection switching unit.

  Then, the load detection unit calculates the pressing load based on the output signals of the three piezoelectric elements 13. This pressure load is preferably set so that, when the pressure sensation (feeling such as the hardness or softness of an object) felt by the operator is substantially the same at each position on the touch surface 11a, almost the same calculation result is obtained. The calculation is performed based on the average value of the output signals of the three piezoelectric elements 13 and the weighted addition value. Further, the three piezoelectric elements 13 are preferably driven by independent drive signals, and the operator has almost the same tactile sensation (sensation such as touch of an object) at each position on the touch surface 11a with almost the same pressure sensation. The amplitude and phase of each drive signal are appropriately changed according to the position and location of the touch surface 11a so that the same tactile sensation in which pressure sense and tactile sense are combined is obtained.

(2) Standard of pressing load The standard of the pressing load that presents the tactile sensation can be appropriately set according to, for example, the load characteristics when the push button switch is pressed. For example, this reference may be set to the same load as the touch sensor 11 reacts to the touch input (the touch input reaction of the touch sensor 11 and the timing to present the tactile sensation are set the same), or the touch sensor 11 A load higher than the load that reacts to the touch input may be set (a setting that delays the timing of presenting the tactile sensation than the response of the touch input of the touch sensor 11). For example, in the case where the input device according to the present embodiment is applied to a mobile terminal, it is preferable that the touch sensor 11 be equal to or more than a load that reacts to a touch input (timing to present a tactile sensation rather than a touch input response of the touch sensor 11) Set to slow down). In addition, this load setting can be set freely by the user so that the elderly user can set it heavier (slower) and the user who frequently emails lightly (faster). .

(3) Driving signal The driving signal for driving the piezoelectric element 13 by the piezoelectric element driving unit 15 can be appropriately set according to the tactile sensation to be presented. For example, in the case of presenting a realistic click tactile sensation that can be felt as “cuckling” obtained when a push button switch used in a mobile terminal is pressed, for example, when the above reference load is applied, for example, 100 Hz to One cycle of a sine wave with a constant frequency of 200 Hz, preferably 170 Hz, is applied to the piezoelectric element 13 as a drive signal, and the touch surface of the touch sensor 11 is vibrated by about 15 μm with a reference pressing load applied. Accordingly, it is possible to present the operator with a real click feeling through the pressing object (pressing object) pressing the touch surface of the touch sensor 11 and recognize that the input operation has been completed. Similarly, in the case of presenting a click tactile sensation that is harder than “kachi”, a sine wave signal or a rectangular wave signal of about 200 Hz to 500 Hz is applied for one cycle as a drive signal.

  When presenting a tactile sensation other than the click tactile sensation, for example, when presenting a soft tactile sensation that can be felt as “Bull” or “Buni”, a sine wave signal of about 200 Hz to 500 Hz is used as a drive signal for two to three cycles. Apply. Alternatively, in the case of presenting a tactile sensation that can be perceived as a vibration felt as “bull”, a sine wave signal of about 200 Hz to 500 Hz is applied as a drive signal for four cycles or more.

It is preferable that the drive signal information presenting these various tactile sensations is stored in a storage unit (not shown) so that the user can appropriately set a drive signal presenting a desired tactile sensation. Then, it is preferable to automatically set the L level time T ₁ of the connection switching signal a shown in FIG. 3 in accordance with the set drive signal.

  In this manner, until the load applied to the touch sensor 11 calculated based on the output of the piezoelectric element 13 satisfies a standard (for example, 1.5 N) that presents a tactile sensation, Then, the piezoelectric element 13 is driven by a predetermined drive signal to vibrate the touch surface 11a to stimulate the sense of touch. Thereby, a tactile sensation is presented to the operator to recognize that the input operation has been completed. Therefore, for example, when a button switch such as a push button switch (push-type button switch) is drawn on the upper part of the touch sensor, the operator operates the touch sensor 11 in the same realistic manner as when the push button switch is operated. Since the input operation can be performed while obtaining the click feeling, there is no sense of incongruity. Further, since the input operation can be performed in conjunction with the consciousness of “pressing” the touch sensor 11, an input error due to simple pressing can be prevented.

  In addition, when the reference pressing load for presenting the tactile sensation is set higher than the load that the touch sensor 11 reacts to touch input (the timing at which the tactile sensation is presented is slower than the touch input reaction of the touch sensor 11), touch The input position is determined in accordance with the touch operation on the surface 11 a, the display mode of the input object at the corresponding portion of the display unit 12 is changed, and then the touch surface 11 a detected based on the output of the piezoelectric element 13. When the pressing load on the head satisfies the criteria for presenting a tactile sensation, the piezoelectric element 13 is driven to present a tactile sensation, and the input position is determined and predetermined processing (for example, execution of a program corresponding to the object) Processing) can be executed. In this case, the operator can confirm the selection of the input object by changing the display mode of the input object displayed on the display unit 12, and the selection is made by pressing the touch surface 11 a and presenting a click feeling. It can be recognized that the input object is determined (executed). Thereby, it is possible to prevent erroneous input by a so-called lost finger.

(Second Embodiment)
FIG. 5 is a functional block diagram showing a schematic configuration of the input device according to the second embodiment of the present invention. In the configuration shown in FIG. 1, this input device has a discharge circuit 16 connected to the piezoelectric element 13, and after the piezoelectric element 13 is driven by the discharge circuit 16, the electric charge remaining in the piezoelectric element 13 is forcibly grounded. It is designed to discharge.

  For example, the discharge circuit 16 is provided with a resistor 41 and a switching transistor 42 for discharge. The collector of the switching transistor 42 is connected to the positive terminal of the piezoelectric element 13 and the emitter is connected to the ground. The base of the switching transistor 42 is connected to the control unit 17 via the resistor 41 and supplies the discharge control signal b from the control unit 17. Since other configurations are the same as those in FIG. 1, the same reference numerals are given to components having the same actions, and the description thereof is omitted.

FIG. 6 is a timing chart showing a schematic operation of the input apparatus according to the present embodiment. Input device according to this embodiment, after driving the piezoelectric element 13 by the piezoelectric element drive unit 15, i.e., from the time the connection switching signal a has passed a predetermined time T ₁ to the L level, the predetermined time T ₃ Meanwhile, the discharge control signal b is set to the H level. As a result, the switching transistor 42 is turned on, and the residual charges accumulated in the piezoelectric element 13 are forcibly discharged to the ground through the collector-emitter passage.

Further, the load detection unit 18, the discharge control signal b until a predetermined time T ₃ has elapsed at the H level, and disables the output voltage Vs from the piezoelectric element 13 (cancel). Thereafter, the load detection unit 18, from the time the predetermined time T ₃ has passed, the enable output voltage Vs from the piezoelectric element 13 and resumes the process of detecting the pressure load based on the output voltage Vs of the piezoelectric element 13. Since other operations are the same as those in the first embodiment, description thereof is omitted.

As described above, in the input device according to the present embodiment, after the piezoelectric element 13 is driven by the piezoelectric element driving unit 15, the residual charge of the piezoelectric element 13 is forcibly discharged to the ground by the discharge circuit 16. after driving 13, a predetermined time (discharge time) before resuming the process of detecting the pressing load by the load detection unit 18 T _3, shorter than the predetermined time T ₂ in the first embodiment, for example, set to about 30ms be able to. Therefore, in addition to the effects of the first embodiment, a tactile sensation is appropriately presented for each input operation even in a so-called repeated input operation in which the same input object displayed on the display unit 12 is continuously input. The effect that it can do is acquired.

(Third embodiment)
FIG. 7 is a timing chart for explaining the schematic operation of the input apparatus according to the third embodiment of the invention. The input device according to the present embodiment. In the configuration shown in FIG. 5, tactile sensation is also presented when the pressed object is released from the touch surface of the touch sensor 11. For this reason, the load detection unit 18 has a first reference voltage Vref1 (corresponding to the reference voltage Vref in the first and second embodiments) corresponding to a reference load for presenting a tactile sensation when pressed, and a tactile sensation when released. A second reference voltage Vref2 corresponding to a reference load for presentation is set. Note that the second reference voltage Vref2 has a polarity different from that of the first reference voltage Vref1. The schematic operation of the input device according to the present embodiment will be described below with reference to FIG.

First, as in the case of the above-described embodiment, the control unit 17 uses the position information from the touch sensor 11 as an input to the input object displayed on the display unit 12, and the load detection unit 18 performs piezoelectric measurement. the output voltage Vs of the device 13, the load of the reference to provide the tactile sensation (e.g., 1.5 N) are determined to be turned to the first reference voltage Vref1 corresponding to a connection switchover signal a predetermined time T ₁ L Level. Accordingly, the piezoelectric element 13 is connected to the piezoelectric element driving unit 15 via the switching control unit 14.

  The control unit 17 drives the piezoelectric element 13 by outputting a predetermined drive signal Vd from the piezoelectric element driving unit 15 in a state where the piezoelectric element 13 is connected to the piezoelectric element driving unit 15. Thereby, the touch panel 11 is vibrated and a tactile sensation is presented to the pressing target pressing the touch surface.

Thereafter, the control unit 17, when the driving period T ₁ of the piezoelectric element 13 by the piezoelectric element drive unit 15 is completed, the connection switching signal a in the H level, connected to the control unit 17 of the piezoelectric element 13 from the piezoelectric element drive unit 15 Is switched. At the same time, the discharge control signal b is set to H level for a predetermined time (discharge time) T ₄ , and the residual charges accumulated in the piezoelectric element 13 are discharged to the ground through the collector-emitter passage of the switching transistor 42. .

Further, the load detection unit 18, the discharge control signal b until a predetermined time T ₄ has elapsed in the H level, does not perform the detection process of the pressing load. When the predetermined time T ₄ has elapsed, the load detection unit 18 resumes the process of detecting the pressure load based on the output voltage Vs of the piezoelectric element 14 from the elapsed time. The predetermined time (discharge time) T _4, as can be secured depressed state of the touch sensor 11 by the pressing target, shorter than the predetermined time T ₃ in the second embodiment is set to, for example, about 20 ms.

Here, the piezoelectric element 13, since the residual charge is connected to ground is discharged at a predetermined time T _4, the end of the predetermined time T _4, the output voltage Vs has become 0V. Therefore, at this time, if the touch sensor 11 is pressed by the pressing target, the output voltage Vs of the piezoelectric element 13 in the pressing state becomes 0 V. Thereafter, along with the release operation of the pressing target, the piezoelectric element When 13 is displaced to return to the original normal state, the output voltage of the piezoelectric element 13 increases to the negative polarity side with the displacement.

Therefore, after the elapse of the predetermined time (discharge time) T ₄ , the control unit 17 causes the load detection unit 18 to output the second reference voltage corresponding to the reference load that provides the tactile sensation when the output voltage Vs of the piezoelectric element 13 is released. are determined to be turned on Vref2, as is the case during the pressing described above, the connection switching signal a as a predetermined time T ₁ by L level, the connection of the piezoelectric element 13 from the controller 17 to the piezoelectric element drive unit 15 Switch.

  Then, as in the case of pressing, the control unit 17 outputs a predetermined drive signal Vd from the piezoelectric element driving unit 15 in a state where the piezoelectric element 13 is connected to the piezoelectric element driving unit 15 and outputs the piezoelectric element. 13 is driven. Thereby, the touch panel 11 is vibrated and a tactile sensation is presented to the pressing target pressing the touch surface.

Thereafter, as in the case of pressing, the control unit 17 sets the connection switching signal a to the H level to switch the connection of the piezoelectric element 13 from the piezoelectric element driving unit 15 to the control unit 17 and discharge control signal b. the predetermined time (discharge time) between T _4, the H-level, to discharge residual electric charge accumulated in the piezoelectric element 13. Thereafter, the load detection unit 18, from the time the discharge time T ₄ has elapsed by the discharge circuit 16, to resume the process of detecting the pressure load based on the output voltage Vs of the piezoelectric element 14, and the detection of the next touch input.

  According to the input device according to the present embodiment, the same effect as in the above embodiment can be obtained. Further, in this embodiment, since the touch target is also released when it is released from the touch sensor 11, the operational feeling of a push button switch such as a metal dome switch is expressed more realistically. Can do. In other words, when pressing, it can present a realistic click tactile sensation that can be felt when the metal dome buckles, and it can be felt when the metal dome returns from buckling when released. A realistic click feel (in this case, release feel) can be presented. Of course, the release tactile sensation is not necessarily the same drive signal as the click tactile sensation.

  Here, the load standard for presenting the release tactile sensation can be set to be the same as the above-described load standard (for example, 1.5 N) that presents the click tactile sensation at the time of pressing, but preferably the tactile sensation at the time of pressing is presented. The value is set to 50% to 80% lower than the load standard (for example, 1N). In this way, when the same position (input object) is continuously input (sequentially hit), the sequential input and the tactile sensation presentation timing match, and a realistic click tactile sensation without discomfort can be presented. In other words, by making the standard load that presents a tactile sensation at the time of release smaller than the standard load that presents a tactile sensation at the time of pressing, the reference load that presents a tactile sensation at the time of release is pressed. Occasionally, the operability during continuous input can be significantly improved by setting the load to be approximately 50% or more of the reference load that sometimes presents a tactile sensation. In addition, by making the reference load that presents a tactile sensation at the time of release approximately 80% or less of the reference load that presents a tactile sensation when pressed, it is possible to cope with minute load changes in the hold state during continuous input.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of invention. For example, in the discharge circuit 16 shown in FIG. 5, the switching transistor 42 can be configured using a semiconductor relay or the like. Furthermore, the piezoelectric element 13 can have a known structure such as a monomorph, a unimorph, a bimorph, and a laminated type in accordance with the area of the touch sensor 11, the vibration amplitude, and the like.

  The present invention can also be effectively applied to an input device that functions as a touch switch in which a touch sensor performs an on / off operation. Furthermore, the input device according to the present invention drives the piezoelectric element when a pressing load detected based on the output of the piezoelectric element satisfies a criterion for presenting a tactile sensation. Here, the case where the pressing load detected based on the output of the piezoelectric element satisfies the standard for presenting tactile sensation may be the time when the detected pressing load reaches a reference value for presenting tactile sensation. The detected pressing load may exceed a reference value that provides tactile sensation, or may be detected when a reference value that provides tactile sensation is detected based on the output of the piezoelectric element.

DESCRIPTION OF SYMBOLS 11 Touch sensor 11a Touch surface 12 Display part 13 Piezoelectric element 14 Connection switching part 15 Piezoelectric element drive part 16 Discharge circuit 17 Control part 18 Load detection part 31 Case 32 Insulator 33 Upper cover 34 Insulator 42 Switching transistor

Claims (4)

A touch sensor for detecting touch input;
One end of which is attached to the touch sensor, a piezoelectric element opposite other end of which is open,
A load detection unit that detects a pressing load on the touch surface of the touch sensor based on an output of the piezoelectric element, and determines whether the pressing load satisfies a criterion for presenting a tactile sensation;
A piezoelectric element driving unit that drives the piezoelectric element so as to present a tactile sensation with respect to a pressing target pressing the touch surface when the load detection unit determines that the reference is satisfied;
The load detector restarts detection of the pressing load after a predetermined time has elapsed after the piezoelectric element is driven by the piezoelectric element driver.
An input device characterized by that. A discharge circuit for discharging the residual charge accumulated in the piezoelectric element;
The discharge circuit discharges residual charges accumulated in the piezoelectric element during the predetermined time;
The input device according to claim 1. The predetermined time is 40 ms or less;
The input device according to claim 1, wherein: A touch sensor for detecting touch input;
One end of which is attached to the touch sensor, a piezoelectric element opposite other end of which is open,
A load detection unit that detects a pressing load on the touch surface of the touch sensor based on an output of the piezoelectric element, and determines whether the pressing load satisfies a criterion for presenting a tactile sensation;
An input device comprising: a piezoelectric element driving unit that drives the piezoelectric element so as to present a tactile sensation to a pressing target pressing the touch surface when the load detection unit determines that the reference is satisfied. Control method,
The piezoelectric element is selectively connected to the load detection unit or the piezoelectric element driving unit,
In a state where the piezoelectric element is connected to the load detection unit, when it is determined that the load detection unit satisfies the reference, the connection of the piezoelectric element from the load detection unit to the piezoelectric element driving unit is switched, Driving the piezoelectric element by the piezoelectric element driving unit;
Next, after driving the piezoelectric element, switching the connection of the piezoelectric element from the piezoelectric element driving unit to the load detecting unit, and restarting detection of the pressing load by the load detecting unit after a predetermined time has elapsed. When,
A method for controlling an input device.

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