DRIVING APPARATUS, VIBRATION GENERATING APPARATUS, ELECTRONIC APPARATUS, AND DRIVING METHOD

Реферат: Provided is a driving apparatus that sets a signal wave in a low-frequency region having a frequency of 10 Hz or more and 250 Hz or less as a modulating wave and outputs to a piezoelectric actuator a driving signal having a waveform obtained by modulating an amplitude of a sine wave in a high-frequency region having a frequency of 20 kHz or more and 40 kHz or less with the modulating wave.

Заявка: 1. A driving apparatus that sets a signal wave in a low-frequency region having a frequency of 10 Hz or more and 250 Hz or less as a modulating wave and outputs to a piezoelectric actuator a driving signal having a waveform obtained by modulating an amplitude of a sine wave in a high-frequency region having a frequency of 20 kHz or more and 40 kHz or less with the modulating wave.2. The driving apparatus according to claim 1 , wherein:the sine wave is set to have voltage gain of −10 dB or more and 0 dB or less andthe modulating wave is set to have voltage gain of −6 dB or more and 0 dB or less.3. The driving apparatus according to claim 2 , wherein:the sine wave is set to have voltage gain of −10 dB, andthe modulating wave is set to have voltage gain of 0 dB.4. A vibration generating apparatus comprising:a vibrating member;a piezoelectric actuator bonded to the vibrating member; anda driving apparatus that sets a signal wave in a low-frequency region having a frequency of 10 Hz or more and 250 Hz or less as a modulating wave and outputs to the piezoelectric actuator a driving signal having a waveform obtained by modulating an amplitude of a sine wave in a high-frequency region having a frequency of 20 kHz or more and 40 kHz or less with the modulating wave, thereby causing the vibrating member to vibrate via the piezoelectric actuator driven by the driving signal.5. An electronic apparatus comprising:{'claim-ref': {'@idref': 'CLM-00004', 'claim 4'}, 'the vibration generating apparatus as set forth in ; and'}an electronic component connected to the vibration generating apparatus.6. A driving method comprising:setting a signal wave in a low-frequency region having a frequency of 10 Hz or more and 250 Hz or less as a modulating wave; andoutputting to a piezoelectric actuator a driving signal having a waveform obtained by modulating an amplitude of a sine wave in a high-frequency region having a frequency of 20 kHz or more and 40 kHz or less with the modulating wave.

Описание: The present disclosure relates to a driving apparatus, a vibration generating apparatus, an electronic apparatus, and a driving method which are associated with tactile sense presentation using vibrations.Various actuators are used in tactile function devices that present tactile senses to users. For example, an electromagnetic actuator such as an eccentric motor and a linear resonant actuator is used for a notification function. Moreover, in addition to these electromagnetic actuators, piezoelectric actuators are also used for a force feedback function.In recent years, the tactile sense technology has been advanced. Regarding the force feedback function in the low-frequency region (100 to 2250 Hz), a wider variety of tactile sense expressions has been provided by complex addition, modulation, and the like of driving signals. Moreover, regarding the high-frequency region (approximately 20 to 40 kHz), a technology by which a tactile sense such as a “rough” texture and a “smooth” texture can be presented has been developed (e.g., see Patent Literature 1).As described above, new tactile senses can be presented to users by using vibrations in the high-frequency region (approximately 20 to 40 kHz). However, for generating a vibration in the high-frequency region, it is necessary to operate a piezoelectric actuator at high speed. There are thus problems of an increase in power consumption, heat generation, noise generation, and the like of the piezoelectric actuator.In view of the above-mentioned circumstances, it is desirable to provide a driving apparatus, a vibration generating apparatus, an electronic apparatus, and a driving method, by which a new tactile sense can be presented while reducing problems caused by a high-frequency vibration of a piezoelectric actuator.According to an embodiment of the present disclosure, there is provided a driving apparatus that sets a signal wave in a low-frequency region having a frequency of 10 Hz or more and 250 Hz or less as a modulating wave and outputs to a piezoelectric actuator a driving signal having a waveform obtained by modulating an amplitude of a sine wave in a high-frequency region having a frequency of 20 kHz or more and 40 kHz or less with the modulating wave.With this configuration, by setting the signal wave in the low-frequency region as the modulating wave and outputting to the piezoelectric actuator the driving signal having the waveform obtained by modulating the amplitude of the sine wave in the high-frequency region with the modulating wave, it is possible to cause the vibrating member to produce a new tactile sense and to prevent the generation of noise while reducing the power consumption and heat generation of the piezoelectric actuator.In the driving apparatus, the sine wave may be set to have voltage gain of −10 dB or more and 0 dB or less and the modulating wave may be set to have voltage gain of −6 dB or more and 0 dB or less.In the driving apparatus, the sine wave may be set to have voltage gain of −10 dB, and the modulating wave may be set to have voltage gain of 0 dB.According to an embodiment of the present disclosure, there is provided a vibration generating apparatus including a vibrating member, a piezoelectric actuator, and a driving apparatus.The piezoelectric actuator is bonded to the vibrating member.The driving apparatus sets a signal wave in a low-frequency region having a frequency of 10 Hz or more and 250 Hz or less as a modulating wave and outputs to the piezoelectric actuator a driving signal having a waveform obtained by modulating an amplitude of a sine wave in a high-frequency region having a frequency of 20 kHz or more and 40 kHz or less with the modulating wave, thereby causing the vibrating member to vibrate via the piezoelectric actuator driven by the driving signal.According to an embodiment of the present disclosure, there is provided an electronic apparatus including a vibration generating apparatus and an electronic component connected to the vibration generating apparatus. The vibration generating apparatus includes a vibrating member, a piezoelectric actuator bonded to the vibrating member, and a driving apparatus that sets a signal wave in a low-frequency region having a frequency of 10 Hz or more and 250 Hz or less as a modulating wave and outputs to the piezoelectric actuator a driving signal having a waveform obtained by modulating an amplitude of a sine wave in a high-frequency region having a frequency of 20 kHz or more and 40 kHz or less with the modulating wave, thereby causing the vibrating member to vibrate via the piezoelectric actuator driven by the driving signal.According to an embodiment of the present disclosure, there is provided a driving method including: setting a signal wave in a low-frequency region having a frequency of 10 Hz or more and 250 Hz or less as a modulating wave; and outputting to a piezoelectric actuator a driving signal having a waveform obtained by modulating an amplitude of a sine wave in a high-frequency region having a frequency of 20 kHz or more and 40 kHz or less with the modulating wave.As described above, in accordance with the present disclosure, it is possible to provide a driving apparatus, a vibration generating apparatus, an electronic apparatus, and a driving method, by which a new tactile sense can be presented while reducing problems caused by a high-frequency vibration of a piezoelectric actuator.These and other objects, features and advantages of the present disclosure will become more apparent in light of the following detailed description of embodiments thereof, as illustrated in the accompanying drawings. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory, and are intended to provide further explanation of the disclosure as claimed.A vibration generating apparatus according to an embodiment of the present disclosure will be described. It should be noted that in each of the figures shown below, the X direction, the Y direction, and the Z direction are three directions orthogonal to one another.[Configuration of Vibration Generating Apparatus]is a schematic diagram of a vibration generating apparatus according to this embodiment. As shown in the figure, the vibration generating apparatus includes a vibrating member , piezoelectric actuators , and a driving apparatus .The vibrating member is a member vibrated by the piezoelectric actuators . is a side view of the vibrating member . The vibrating member can be a plate-like member formed from materials such as glass and plastic, and is, for example, a liquid-crystal panel, a casing of an electronic apparatus, or the like. The vibrating member is not particularly limited to the shape and size of the vibrating member .The piezoelectric actuators are bonded to the vibrating member to generate vibrations. The piezoelectric actuators each include a positive electrode, a negative electrode, and a piezoelectric material layer. When a voltage is applied between the positive electrode and the negative electrode, the piezoelectric material layer is deformed due to the reverse piezoelectric effect, such that a vibration is generated. The piezoelectric actuators may each have a laminated structure in which positive electrodes and negative electrodes are alternately laminated with piezoelectric material layers each interposed therebetween. Alternatively, the piezoelectric actuators may have another structure.As shown in , the piezoelectric actuator can be disposed at each of opposite end portions of the vibrating member in a long side direction (x direction). Moreover, the number of the piezoelectric actuators is not limited to two, and one or three or more piezoelectric actuators may be disposed. The piezoelectric actuators can be joined to the vibrating member by bonding or the like.The driving apparatus outputs driving signals to the piezoelectric actuators . The driving apparatus is connected to the positive electrodes and the negative electrodes of the piezoelectric actuators and outputs voltage waveforms to be described later between the positive electrodes and the negative electrodes as the driving signals. The driving apparatus is, for example, an amplifier.The vibration generating apparatus has the above-mentioned configuration. The vibration generating apparatus can be mounted on various electronic apparatuses such as a smartphone and a tactile function device having other electronic components.[Regarding Driving Signal]The waveforms of the driving signals output from the driving apparatus to the piezoelectric actuators will be described. It should be noted that a sine wave is used as a signal wave in a low-frequency region for the sake of convenience in the following description, though not limited thereto.shows a voltage waveform and a current waveform as a sine wave in a high-frequency region having a frequency of 20 kHz or more and 40 kHz or less. When the voltage waveform shown in is applied from the driving apparatus to each of the piezoelectric actuators as the driving signal, current having the current waveform shown in flows.Thus, in a case where the sine waves in the high-frequency region are used as the driving signals, ultrasonic standing waves are formed in the vibrating member and a levitation phenomenon due to the ultrasonic standing waves occurs when the user touches the vibrating member . Accordingly, when the user slides a finger on the vibrating member , the user can feel a tactile sense such as a “smooth” texture and a “rough” texture.However, in a case where such sine waves in the high-frequency region are used as the driving signals, the driving current of the piezoelectric actuators increases and the power consumption increases. Moreover, the heat generation of the piezoelectric actuators also increases. In addition, noise may be generated between the user's finger and the vibrating member .shows a voltage waveform and a current waveform as a sine wave in the low-frequency region having a frequency of 10 Hz or more and 250 Hz or less. When the voltage waveform shown in is applied from the driving apparatus to each of the piezoelectric actuators as the driving signal, current having the current waveform shown in flows.The vibration in the low-frequency region of 10 Hz or more and 250 Hz or less is a vibration that can be easily sensed by Meissner's corpuscles, Pacinian corpuscles, and the like, which are mechanoceptors in human skin. When such sine waves in the low-frequency region are used as the driving signals, standing waves are formed in the vibrating member and the user can feel a sense such as a vibration and an electrical shock.shows a voltage waveform and a current waveform including a waveform of an amplitude-modulated wave obtained by modulating the amplitude of the sine wave in the high-frequency region with a modulating wave as which the sine wave in the low-frequency region (signal wave) is used. is an enlarged diagram of . When the voltage waveform shown in is applied as the driving signal to each of the piezoelectric actuators from the driving apparatus , current having the current waveform shown in flows.shows only the voltage waveform shown in and shows only the voltage waveform shown in . A wave having a smaller wavelength, which is indicated by W1 in , is the sine wave in the high-frequency region and a wave having a larger wavelength, which is indicated by W2, is the sine wave in the low-frequency region. Hereinafter, the sine wave in the high-frequency region will be referred to as a high-frequency wave W1 and the sine wave in the low-frequency region will be referred to as a low-frequency wave W2.In the waveform shown in , the low-frequency wave W2 is formed as changes in amplitude of the high-frequency wave W1, i.e., the waveform shown in is an amplitude-modulated wave having the high-frequency wave W1 as a carrier wave and having the low-frequency wave W2 as a modulating wave. It should be noted that the high-frequency wave W1 has a frequency of 20 kHz or more and 40 kHz or less and the low-frequency wave W2 has a frequency of 10 Hz or more and 250 Hz or less.The voltage gain of the high-frequency wave W1 is favorably −10 dB or more and 0 dB or less and the voltage gain of the low-frequency wave W2 is favorably −6 dB or more and 0 dB or less. is a schematic diagram showing a relationship between the waveform of the amplitude-modulated wave and the voltage gain. Assuming that as shown in the figure, the amplitude of the “peak” of the amplitude-modulated wave is represented as an amplitude a and the amplitude of the “valley bottom” is represented as an amplitude b, the degree of modulation m is expressed by the following Equation (1). As shown in the following Equation (1), as the amplitude b becomes lower relative to the amplitude a, the degree of modulation m becomes higher.=()/()  Equation (1)Also in , when the voltage gain of the low-frequency wave W2 is increased, the “valley bottom” of the low-frequency wave W2 is deeper, and when the voltage gain of the low-frequency wave W2 is set to 0 dB, the amplitude of the “valley bottom” is minimum as indicated by the white arrows in . Moreover, when the voltage gain of the low-frequency wave W2 is reduced to be closer to −6 dB, the “valley bottom” of the low-frequency wave W2 is shallower and the amplitude is larger. When the voltage gain of the low-frequency wave W2 is further reduced to be closer to −10 dB, the amplitude b of the “valley bottom” of the low-frequency wave W2 is equal to the amplitude of the “peak” and the “valley” is not formed.In this embodiment, the voltage gain of the high-frequency W1 and the low-frequency W2 is adjusted to a range in which the “valley” is formed. Specifically, the voltage gain of the high-frequency wave W1 is favorably −10 dB or more and 0 dB or less and the voltage gain of the low-frequency wave W2 is favorably −6 dB or more and 0 dB or less. Moreover, the voltage gain of the high-frequency wave W1 is more favorably −10 dB and the voltage gain of the low-frequency wave W2 is more favorably 0 dB.When the driving apparatus outputs the driving signal having the voltage waveform of the amplitude-modulated wave shown in to each of the piezoelectric actuators , standing waves due to the high-frequency wave W1 are formed in the vibrating member by the piezoelectric actuators and a levitation phenomenon occurs. Furthermore, a vibration that stimulates receptors such as Meissner's corpuscles and Pacinian corpuscles is generated in the vibrating member due to the low-frequency wave W2.With this configuration, when the user touches the vibrating member with a finger, the low-frequency wave W2 sensitively presents a tactile sense to the finger. Moreover, when the user presses the finger against the vibrating member , the user receives a squeeze effect due to the levitation phenomenon and also receives a strong low-frequency vibration. The user thus feels a totally new tactile sense.Furthermore, since the amplitude of the high-frequency wave W1 is modulated, the current average of the entire waveform is reduced as compared to a case where the amplitude of the high-frequency wave W1 is not modulated, and it is possible to reduce the power consumption and heat generation. In addition, although noise may be generated between the user's finger and the vibrating member in a case where the sine wave in the high-frequency region as shown in is used as the driving signal, it is possible to prevent the generation of such noise in the case of the amplitude-modulated wave shown in .The vibration generating apparatus according to the above-mentioned embodiment was manufactured, and the apparent power was measured when the driving signal having the voltage waveform of the amplitude-modulated wave shown in was output from the driving apparatus to the piezoelectric actuator. Table 1 shows a gain ratio, a peak-to-peak voltage (Vpp), a voltage effective value (rms), current, and apparent power.The gain ratio refers to a ratio of the voltage gain of the high-frequency wave W1 and the voltage gain of the low-frequency wave W2. The high-frequency wave W1 was set to have a frequency of 25 kHz and the low-frequency wave W2 was set to have a frequency of 100 Hz. As shown in Table 1, the voltage gain of the high-frequency wave W1 was set to −10 dB, the voltage gain of the low-frequency wave W2 was varied between −10 dB to 0 dB, and the apparent power at a predetermined input voltage (rms of 5.5 V) was measured.is a graph showing a relationship between the gain ratio and the apparent power. As it can be seen from the figure, the apparent power decreases when the voltage gain of the low-frequency wave W2 is made closer to 0 dB from −10 dB. Therefore, it is possible to reduce the power consumption by setting the voltage gain of the low-frequency wave W2 to be higher than the voltage gain of the high-frequency wave W1.While the embodiment of the present disclosure has been described, the present disclosure is not limited to the embodiment described above, and it should be appreciated that the present disclosure may be variously modified.