JP4838280B2 - Touch panel type input device - Google Patents

Description

  The present invention relates to a touch panel input device having a tactile feedback function and a charging function.

  Since the surface of the touch panel is flat and smooth, there is a situation in which it is difficult for the user to determine whether or not the user can operate correctly compared to a mechanical switch. For this reason, conventionally, a touch panel has been proposed in which vibration is given to the fingertip of the operating user to feed back the feeling of operation. As described above, the feedback method for applying vibration to the fingertip of the user who operates is called tactile feedback.

  FIG. 7 is a diagram illustrating a schematic configuration of a touch panel type input device having a haptic feedback function described in Japanese Patent Application Laid-Open No. 2007-34938. The touch panel type input device 60 has a function of performing acoustic feedback and generating acoustics to perform acoustic feedback. That is, the piezoelectric actuator 57 generates vibration that reproduces the sense of touch, and generates sound from the piezoelectric actuator 57 or the touch panel 53 to which the piezoelectric actuator 57 is attached.

The control unit 55 receives a signal representing the contact position on the touch panel 53 and outputs a control signal to the waveform shaping circuit 56 via the interface 61 so as to generate a predetermined tactile vibration according to the position. An acoustic signal is output to the mixing circuit 62. The waveform shaping circuit 56 outputs a signal for driving the piezoelectric actuator 57 to the mixing circuit 62 based on the control signal. The mixing circuit 62 mixes the acoustic signal and the tactile signal and outputs these mixed signals to the power amplifier 63. The power amplifier 63 drives the piezoelectric actuator 57 based on the input mixed signal. Thereby, the piezoelectric actuator 57 generates vibration that reproduces the tactile sense, and the piezoelectric actuator 57 or the touch panel 53 to which the piezoelectric actuator 57 is attached generates sound.
JP 2007-34938 A

  However, in the touch panel type input device shown in FIG. 7, in order to perform tactile feedback and sound generation, the piezoelectric actuator 57 or the touch panel 53 to which the piezoelectric actuator 57 is attached functions as a speaker. Since the sound generating signal is handled separately, circuits such as the interface 61 and the mixing circuit 62 are required, and the cost increase cannot be denied.

  The present invention has been made in view of such circumstances, and provides a touch panel type input device that has a tactile feedback and acoustic feedback function, a charging function, and can achieve downsizing and power saving. For the purpose.

  (1) In order to achieve the above object, the present invention takes the following measures. That is, the touch panel type input device according to the present invention is a touch panel type input device having a touch panel that detects a contact at a position corresponding to a display position of an image displayed on a display device and generates an input signal. A piezoelectric actuator that drives in a direction perpendicular to the touch panel and applies vibration to the touch panel; and a digital signal processor that outputs at least one of an acoustic signal or a tactile signal as a drive signal based on an input signal generated by the touch panel; A class D amplifier that drives the piezoelectric actuator based on a drive signal output from the digital signal processor, and an AC voltage generated in the piezoelectric actuator by vibration applied to the touch panel from the outside is converted into a DC voltage. Rectifier circuit and front A voltage determination circuit for determining whether or not the converted DC voltage is greater than a threshold; and a switching circuit that outputs the converted DC voltage to a battery when the converted DC voltage is greater than the threshold as a result of the determination It is characterized by providing these.

  As described above, since the class D amplifier is used to drive the piezoelectric actuator, heat generation can be suppressed to a small value. As a result, a heat sink for diffusing heat becomes unnecessary, and it is easy to reduce the size. Further, since the piezoelectric element has a capacitive property, it is possible to eliminate the LC filter capacitor required for the class D amplifier. In addition, since a digital signal processor advantageous for signal processing is used, the tactile signal and the acoustic signal can be mixed and input to the class D amplifier as a mixed signal. This makes it possible to reduce the size of the apparatus and reduce the cost. Further, the AC voltage generated in the piezoelectric actuator is converted into a DC voltage, and when the converted DC voltage is larger than the threshold value, the converted DC voltage is output to the battery, so that the battery can be charged. As a result, it is possible to contribute to power saving and cost reduction.

  (2) Moreover, the touch panel type input device of the present invention is a touch panel type input device having a touch panel that detects a contact at a position corresponding to a display position of an image displayed on the display device and generates an input signal. A digital actuator that drives in a vertical direction with respect to the flat touch panel and outputs at least one of an acoustic signal or a tactile signal as a drive signal based on a piezoelectric actuator that vibrates the touch panel and an input signal generated by the touch panel A signal processor, a class D amplifier that drives the piezoelectric actuator based on a drive signal output from the digital signal processor, and an AC voltage generated in the piezoelectric actuator by vibration applied to the touch panel from the outside is greater than a threshold value Determine whether And a switching circuit that outputs an AC voltage generated in the piezoelectric actuator to a rectifier circuit that converts the AC voltage to a DC voltage when the AC voltage generated in the piezoelectric actuator is greater than a threshold value as a result of the determination. And a rectifier circuit that converts the input AC voltage into a DC voltage and outputs the DC voltage to the battery.

  As described above, since the class D amplifier is used to drive the piezoelectric actuator, heat generation can be suppressed to a small value. As a result, a heat sink for diffusing heat becomes unnecessary, and it is easy to reduce the size. Further, since the piezoelectric element has a capacitive property, it is possible to eliminate the LC filter capacitor required for the class D amplifier. In addition, since a digital signal processor advantageous for signal processing is used, the tactile signal and the acoustic signal can be mixed and input to the class D amplifier as a mixed signal. This makes it possible to reduce the size of the apparatus and reduce the cost. Further, the AC voltage generated in the piezoelectric actuator is converted into a DC voltage, and when the converted DC voltage is larger than the threshold value, the converted DC voltage is output to the battery, so that the battery can be charged. As a result, it is possible to contribute to power saving and cost reduction.

  (3) In the touch panel type input device of the present invention, the rectifier circuit is a voltage doubler rectifier circuit.

  Thus, since the rectifier circuit is a voltage doubler rectifier circuit, it is possible to output a voltage larger than the input voltage.

  (4) In the touch panel type input device of the present invention, the piezoelectric actuator is a bimorph type piezoelectric actuator in which piezoelectric elements are stacked.

  As described above, since the piezoelectric actuator is a bimorph type, it is possible to exhibit a driving force stronger than that of the unimorph type. In addition, since the piezoelectric elements are stacked, it can be driven at a voltage lower than that of a single layer. This makes it possible to realize a touch panel type input device suitable for a portable information terminal or a mobile phone.

  (5) Further, in the touch panel type input device of the present invention, the class D amplifier is a class D amplifier whose output unit adopts a BTL (Bridged Transless) configuration.

  Thus, since the BTL configuration in which two class D amplifiers are substantially prepared and one of them is driven in reverse phase, the load voltage can be apparently doubled. As a result, larger vibrations or sounds can be obtained.

  According to the present invention, since the class D amplifier is used to drive the piezoelectric actuator, heat generation can be suppressed to a small value. As a result, a heat sink for diffusing heat becomes unnecessary, and it is easy to reduce the size. Further, since the piezoelectric element has a capacitive property, it is possible to eliminate the LC filter capacitor required for the class D amplifier. In addition, since a digital signal processor advantageous for signal processing is used, the tactile signal and the acoustic signal can be mixed and input to the class D amplifier as a mixed signal. This makes it possible to reduce the size of the apparatus and reduce the cost. Further, the AC voltage generated in the piezoelectric actuator is converted into a DC voltage, and when the converted DC voltage is larger than the threshold value, the converted DC voltage is output to the battery, so that the battery can be charged. As a result, it is possible to contribute to power saving and cost reduction.

(First embodiment)
FIG. 1 is a diagram showing a schematic configuration of a touch panel input device according to the first embodiment of the present invention. This touch panel type input device 1 has a tactile feedback function and an acoustic feedback function. The touch panel 2 generates an input signal by detecting a contact at a position corresponding to a display position of an image displayed on a display device (not shown). The touch panel circuit 3 processes a signal obtained from the touch panel 2 to generate a signal representing a position where the user's fingertip contacts on the panel surface of the touch panel 2.

  The digital signal processor 4 receives a signal representing a contact position on the touch panel 2 and classifies a mixed signal obtained by mixing the acoustic signal and the tactile signal so as to generate predetermined sound and tactile vibration according to the position. Output to the amplifier 5. The digital signal processor 4 does not distinguish between an acoustic signal and a tactile signal, and mixes and outputs both.

  The class D amplifier 5 drives the piezoelectric actuator 6 based on the mixed signal input from the digital signal processor 4. The class D amplifier 5 is an amplifier that converts an input analog signal into a PWM (Pulse Wide Modulation) signal, and outputs the analog signal amplified in terms of power by passing the PWM signal passing through the switching circuit through an LC filter. is there. Since the piezoelectric element has capacitance, it is possible to eliminate the LC filter capacitor required for the class D amplifier. In addition, when a piezoelectric element (piezoelectric actuator) that is a capacitive load is driven by a general analog amplifier, the phase of the current is shifted by 90 degrees from the voltage, so the heat generation is large, whereas the class D amplifier is amplified by switching. Since heat generation is small and a heat sink for diffusing heat is not required, it is advantageous for miniaturization.

  FIG. 2 is a block diagram showing a schematic configuration of the class D amplifier. The class D amplifier 5 includes a PWM circuit 5a that performs PWM modulation, an FET driver 5b that drives an FET, two FETs 5c, and a choke coil 5d. The PWM circuit 5a performs pulse width modulation on the input signal, and the FET driver 5b drives the FET 5c on the basis of the pulse width modulated signal. The output signal of the FET 5c is output via the choke coil 5d. An LC filter necessary for the class D amplifier is formed by the capacitance of the choke coil 5d and the piezoelectric actuator 6. That is, since the piezoelectric actuator 6 has a capacitive property, in this embodiment, a capacitor in the LC filter is unnecessary. By driving the piezoelectric actuator 6 with such a class D amplifier 5, the piezoelectric actuator 6 or the touch panel 2 to which the piezoelectric actuator 6 is attached generates sound. In FIG. 2, the Mute signal is a signal for turning off the MOSFET 5 c at the output stage in the class D amplifier 5.

  Here, the output unit of the class D amplifier 5 may adopt a BTL (Bridged Transless) configuration. FIG. 3 is a diagram showing a schematic configuration of a class D amplifier adopting a BTL configuration. In FIG. 3, a class D amplifier 5-2 includes a PWM circuit 5a-2 that performs PWM modulation, two FET drivers 5b-2 that drive FETs, four FETs 5c-2, two choke coils 5d-2, and NOT. The circuit 5e is configured. The PWM circuit 5a-2 performs pulse width modulation on the input signal. The NOT circuit 5e inverts the phase of the output of the PWM circuit 5a-2. The two FET drivers 5b-2 drive each FET 5c-2 based on the pulse width modulated signal. The output signal of each FET 5c-2 is output via the choke coil 5d-2. An LC filter necessary for the class D amplifier is formed by the capacitance of the choke coil 5d-2 and the piezoelectric actuator 6-2. In this way, by substantially preparing two class D amplifiers and adopting a BTL configuration in which one is driven in reverse phase, the load voltage can be apparently doubled. As a result, larger vibrations or sounds can be obtained. In FIG. 3, the Mute signal is a signal for turning off the MOSFET 5c-2 at the output stage in the class D amplifier 5-2.

  In addition, about operation of the touch panel 2 by a user, you may touch with a finger | toe and you may use the stylus pen 7 as shown in FIG.

  When the user touches the wrong position on the touch panel 2 by changing the form of the analog signal output by the digital signal processor 4, such as when the user touches an error tactile or a button is pressed. Various tactile feedback such as a tactile sense can be performed.

  Further, the touch panel type input device 1 has a rectifier circuit 8 that converts an AC voltage generated in the piezoelectric actuator 6 by a vibration applied to the touch panel 2 from the outside into a DC voltage, and a DC voltage converted by the rectifier circuit 8 is specified. A voltage determination circuit 9 for determining whether or not the value (threshold value) is greater is provided. Further, as a result of the determination by the voltage determination circuit 9, a second switching circuit 11 that outputs a DC voltage to the battery 10 and a second function that separates the rectifier circuit 8 when the piezoelectric actuator 6 is driven by the class D amplifier 5 are provided. Switching circuit 12. The second switching circuit 12 is turned ON or OFF according to the input from the NOT circuit 13.

  In such a touch panel type input device 1, for example, when the device is in a dormant state, the class D amplifier 5 is turned off by the Mute signal, and the class D amplifier output stage MOSFET 5 c is turned off. The piezoelectric actuator 6 is disconnected. At this time, the second switching circuit 12 is turned on by a signal from the NOT circuit 13 to connect the piezoelectric actuator 6 and the rectifier circuit 8. Here, when the user touches the touch panel 2, an alternating voltage is generated in the piezoelectric actuator 6 with the vibration. The AC voltage is converted into a DC voltage by the rectifier circuit 8. When the obtained DC voltage is higher than a specified voltage of the battery 10, for example, the first switching circuit 11 provided at the subsequent stage of the rectifier circuit 8 is turned ON. The DC voltage is input to the battery 10. This makes it possible to charge the battery.

(Second Embodiment)
FIG. 4 is a diagram illustrating a schematic configuration of the touch panel input device 20 according to the second embodiment. In the second embodiment, the second switching circuit 12 in FIG. 1 has a function of connecting the DC voltage of the first switching circuit 11 to the rectifier circuit, whereby the first switching circuit 11 shown in FIG. Is omitted. In this case, the part for determining the voltage is the previous stage of the switching circuit 21 as shown in FIG. That is, in FIG. 4, the magnitude of the AC voltage generated by the piezoelectric actuator 6 is determined by the voltage determination circuit 9. The switching circuit 21 is ON / OFF controlled by the Mute signal of the class D amplifier 5 from the digital signal processor 4 and the voltage determination circuit 9 via the NOT circuit 13, but the class D amplifier 5 is turned off. Therefore, when the Mute signal is enabled (asserted) and the AC voltage generated by the piezoelectric actuator 6 is higher than the specified value (threshold value), the switching circuit 21 is turned on.

(Third embodiment)
FIG. 5 is a diagram illustrating a schematic configuration of a touch panel type input device according to the third embodiment. The voltage applied to the piezoelectric actuator 6, the amount of displacement of the piezoelectric actuator 6, and the amount of voltage generated in the piezoelectric actuator 6 when the piezoelectric actuator 6 is displaced are basically substantially equal (however, they vary depending on the impedance of the rectifier circuit). ). Therefore, for example, a voltage of 3.3 V or more is not generated unless a displacement greater than the displacement amount of the piezoelectric actuator obtained by applying 3.3 V by the class D amplifier 5 is generated in the piezoelectric actuator. Therefore, in the third embodiment, a voltage doubler rectifier circuit 50 such as a Cockcroft-Walton circuit is used as the rectifier circuit. Other configurations are the same as those of the first embodiment shown in FIG.

  FIG. 6 is a diagram illustrating a schematic configuration of the voltage doubler rectifier circuit. In the voltage doubler rectifier circuit 50, when the AC voltage generated by the piezoelectric actuator 6 is input, the capacitor 50c is charged when the ground side terminal of the diode 50b has a higher potential. Next, when the input terminal becomes a high potential, the input potential and the charged value of the capacitor 50c are in series, and the capacitor 50d is charged by the diode 50b. As a result, the output voltage of the capacitor 50d is nearly twice the input value. Thus, since the rectifier circuit is the voltage doubler rectifier circuit 50, it is possible to output a voltage larger than the input voltage.

  As described above, according to the touch panel type input device according to the present embodiment, since the class D amplifier is used to drive the piezoelectric actuator, it is possible to suppress heat generation, and as a result, there is a heat sink that diffuses heat. It becomes unnecessary and it becomes easy to reduce the size. Further, since the piezoelectric element has a capacitive property, it is possible to eliminate the LC filter capacitor required for the class D amplifier. In addition, since a digital signal processor advantageous for signal processing is used, the tactile signal and the acoustic signal can be mixed and input to the class D amplifier as a mixed signal. This makes it possible to reduce the size of the apparatus and reduce the cost. Further, the AC voltage generated in the piezoelectric actuator is converted into a DC voltage, and when the converted DC voltage is larger than the threshold value, the converted DC voltage is output to the battery, so that the battery can be charged. As a result, it is possible to contribute to power saving and cost reduction.

It is a figure which shows schematic structure of the touchscreen type input device which concerns on the 1st Embodiment of this invention. It is a block diagram which shows schematic structure of a class D amplifier. It is a figure which shows schematic structure of the class D amplifier which took BTL structure. It is a figure which shows schematic structure of the touchscreen type input device which concerns on 2nd Embodiment. It is a figure which shows schematic structure of the touchscreen type input device which concerns on 3rd Embodiment. It is a figure which shows schematic structure of a voltage doubler rectifier circuit. It is a figure which shows schematic structure of the conventional touchscreen type input device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Touch panel type input device 2 Touch panel 3 Touch panel circuit 4 Digital signal processor 5 Class D amplifier 5a PWM circuit 5b FET driver 5c FET
5d Choke coil 5-2 Class D amplifier 5a-2 PWM circuit 5b-2 FET driver 5c-2 FET
5d-2 choke coil 6 piezoelectric actuator 6-2 piezoelectric actuator 7 stylus pen 8 rectifier circuit 9 voltage determination circuit 10 battery 11 first switching circuit 12 second switching circuit 13 NOT circuit 21 switching circuit 50 voltage doubler rectifier circuit

Claims (5)

A touch panel type input device having a touch panel that detects a contact at a position corresponding to a display position of an image displayed on a display device and generates an input signal,
A piezoelectric actuator that drives in a vertical direction with respect to the flat touch panel, and that vibrates the touch panel;
A digital signal processor that outputs at least one of an acoustic signal or a tactile signal as a drive signal based on an input signal generated by the touch panel;
A class D amplifier for driving the piezoelectric actuator based on a drive signal output from the digital signal processor;
A rectifier circuit that converts an AC voltage generated in the piezoelectric actuator by vibration applied to the touch panel from the outside into a DC voltage;
A voltage determination circuit for determining whether the converted DC voltage is greater than a threshold;
A touch panel type input device comprising: a switching circuit that outputs the converted DC voltage to a battery when the converted DC voltage is larger than a threshold value as a result of the determination. A touch panel type input device having a touch panel that detects a contact at a position corresponding to a display position of an image displayed on a display device and generates an input signal,
A piezoelectric actuator that drives in a vertical direction with respect to the flat touch panel, and that vibrates the touch panel;
A digital signal processor that outputs at least one of an acoustic signal or a tactile signal as a drive signal based on an input signal generated by the touch panel;
A class D amplifier for driving the piezoelectric actuator based on a drive signal output from the digital signal processor;
A voltage determination circuit for determining whether or not an AC voltage generated in the piezoelectric actuator by vibration applied to the touch panel from outside is greater than a threshold;
As a result of the determination, when the AC voltage generated in the piezoelectric actuator is larger than a threshold value, a switching circuit that outputs the AC voltage generated in the piezoelectric actuator to a rectifier circuit that converts the AC voltage into a DC voltage;
A rectifier circuit that converts an input AC voltage into a DC voltage and outputs the DC voltage to a battery, and a touch panel type input device.   The touch panel type input device according to claim 1, wherein the rectifier circuit is a voltage doubler rectifier circuit.   The touch panel type input device according to any one of claims 1 to 3, wherein the piezoelectric actuator is a bimorph piezoelectric actuator in which piezoelectric elements are laminated.   The touch panel type input device according to any one of claims 1 to 4, wherein the class D amplifier is a class D amplifier whose output unit adopts a BTL configuration.

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