Vibration generating device and electronic device

Abstract

To provide a vibration generating device that can generate vibrations to express a variety of tactile sense, and an electronic instrument.SOLUTION: A vibration generating device is equipped with a first piezoelectric actuator and a second piezoelectric actuator. The first piezoelectric actuator comprises a first piezoelectric body layer, a first positive internal electrode and a first negative internal electrode opposing to the first positive internal electrode through the first piezoelectric body layer, which when a voltage is applied to a space between the first positive internal electrode and the first negative internal electrode, extends and contracts along a first direction which is parallel to electrode planes of the first positive internal electrode and the first negative internal electrode. The second piezoelectric actuator is laminated on the first piezoelectric actuator and comprises a second piezoelectric body layer, a second positive internal electrode and a second negative internal electrode opposing to the second positive internal electrode through the second piezoelectric body layer, which when a voltage is applied to a space between the second positive internal electrode and the second negative internal electrode, extends and contracts along a second direction which is perpendicular to electrode planes of the second positive internal electrode and the second negative internal electrode and is perpendicular to the first direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vibration generating device and an electronic device that provide a tactile sensation by vibration. [Background technology]

[0002] Various actuators are used in haptic function devices that present tactile sensations to users. For example, electromagnetic actuators such as eccentric motors and linear resonant actuators are used for notification functions. In addition to these electromagnetic actuators, piezoelectric actuators are also used for force feedback functions.

[0003] In recent years, tactile technology has become more sophisticated, and in addition to notification functions, technology has been developed that can also reproduce tactile sensations such as roughness and smoothness (see, for example, Patent Document 1). Furthermore, there is a demand for surfaces with different tactile sensations in different areas on liquid crystal panels of mobile devices. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 8-314369 Summary of the Invention [Problem to be solved by the invention]

[0005] Here, notification functions can be achieved by vibrations in the low-frequency range (approximately 1 to 250 Hz), while tactile sensations such as roughness and smoothness are achieved by vibrations in the high-frequency range (approximately 20 to 100 kHz). Specifically, tactile sensations are achieved by placing actuators on both ends of the panel as driving sources and utilizing the levitation phenomenon at the fingertips caused by standing waves formed on the panel. Because the panel vibrates due to the same wave motion being transmitted throughout the panel, only a single tactile sensation can be expressed.

[0006] In view of the above circumstances, an object of the present invention is to provide a vibration generating device and an electronic device that are capable of expressing a variety of tactile sensations through vibration. [Means for solving the problem]

[0007] To achieve the above object, a vibration generator according to one aspect of the present invention includes a first piezoelectric actuator and a second piezoelectric actuator. The first piezoelectric actuator includes a first piezoelectric layer made of a piezoelectric material, a first positive internal electrode provided in the first piezoelectric layer, and No. 1 The first positive internal electrode is provided in the piezoelectric layer and is connected to the first positive internal electrode via the first piezoelectric layer. In the second direction and a first negative electrode internal electrode facing each other, and when a voltage is applied between the first positive electrode internal electrode and the first negative electrode internal electrode, the first positive electrode internal electrode and the first negative electrode internal electrode expand and contract along a first direction parallel to the electrode surfaces of the first positive electrode internal electrode and the first negative electrode internal electrode. The second piezoelectric actuator is laminated on the first piezoelectric actuator and includes a second piezoelectric layer made of a piezoelectric material, a second positive electrode internal electrode provided in the second piezoelectric layer, and a second positive electrode internal electrode provided in the second piezoelectric layer and connected to the second positive electrode via the second piezoelectric layer. In the second direction above and a second negative electrode internal electrode facing each other, and when a voltage is applied between the second positive electrode internal electrode and the second negative electrode internal electrode, a voltage perpendicular to the electrode surfaces of the second positive electrode internal electrode and the second negative electrode internal electrode is applied. The above stretches along the second direction.

[0008] the first piezoelectric actuator has a first end face which is an end face perpendicular to the first direction and parallel to the second direction, a second end face which is an end face perpendicular to the first direction and parallel to the second direction and opposite to the first end face, a third end face which is an end face parallel to the first direction and the second direction, and a fourth end face which is an end face parallel to the first direction and the second direction and opposite to the third end face, an end of the first positive internal electrode is exposed at the first end face, and an end of the first negative internal electrode is exposed at the second end face, The second piezoelectric actuator may have a fifth end face which is an end face perpendicular to the first direction and parallel to the second direction, a sixth end face which is an end face perpendicular to the first direction and parallel to the second direction and opposite to the fifth end face, a seventh end face which is an end face parallel to the first direction and the second direction, and an eighth end face which is an end face parallel to the first direction and the second direction and opposite to the seventh end face, and an end of the second positive internal electrode may be exposed at the seventh end face, and an end of the second negative internal electrode may be exposed at the eighth end face.

[0009] the vibration generator includes a plurality of the second piezoelectric actuators arranged in a row along the first direction, the seventh end face is a surface continuous with the third end face, The eighth end face may be a surface that is continuous with the fourth end face.

[0010] The vibration generating device is positive electrode external electrodes provided on the first end surface, the third end surface, and the seventh end surface, and electrically connected to the first positive electrode internal electrode and the second positive electrode internal electrode; negative electrode external electrodes provided on the second end surface, the fourth end surface, and the eighth end surface, and electrically connected to the first negative electrode internal electrode and the second negative electrode internal electrode; may further comprise:

[0011] The vibration generating device is a first positive electrode external electrode provided on the first end surface and electrically connected to the first positive electrode internal electrode; a first negative electrode external electrode provided on the second end surface and electrically connected to the first negative electrode internal electrode; a second positive electrode external electrode provided on the seventh end surface and electrically connected to the second positive electrode internal electrode; a second negative electrode external electrode provided on the eighth end surface and electrically connected to the second negative electrode internal electrode; may further comprise:

[0012] the vibration generator includes a plurality of the second piezoelectric actuators arranged in two rows along a first direction; the seventh end surface faces the seventh end surface of the adjacent second piezoelectric actuator; The eighth end face may be a surface that is continuous with the third end face and the fourth end face.

[0013] The vibration generating device is a positive electrode external electrode provided on the first end surface and the seventh end surface and electrically connected to the first positive electrode internal electrode and the second positive electrode internal electrode; negative electrode external electrodes provided on the second end surface, the third end surface, the fourth end surface, and the eighth end surface, and electrically connected to the first negative electrode internal electrode and the second negative electrode internal electrode; may further comprise:

[0014] The vibration generating device is a first positive electrode external electrode provided on the first end surface and electrically connected to the first positive electrode internal electrode; a first negative electrode external electrode provided on the second end surface and electrically connected to the first negative electrode internal electrode; a second positive electrode external electrode provided on the seventh end surface and electrically connected to the second positive electrode internal electrode; a second negative electrode external electrode provided on the eighth end surface and electrically connected to the second negative electrode internal electrode; may further comprise:

[0015] The vibration generating device is The device may further include a drive unit that supplies, to the positive external electrode and the negative external electrode, a drive signal having a waveform obtained by amplitude-modulating a sine wave in a high frequency region having a frequency of 20 kHz or more and 100 kHz or less with a signal wave in a low frequency region having a frequency of 1 Hz or more and 250 Hz or less as a modulating wave.

[0016] The vibration generator may further include a drive unit that supplies a drive signal having a waveform obtained by amplitude-modulating a sine wave in a high frequency range having a frequency of 20 kHz to 100 kHz using a signal wave in a low frequency range having a frequency of 1 Hz to 250 Hz as a modulating wave to the first positive external electrode and the first negative external electrode. Vibration generator.

[0017] To achieve the above object, an electronic device according to an aspect of the present invention includes a first piezoelectric actuator and a second piezoelectric actuator. The first piezoelectric actuator includes a first piezoelectric layer made of a piezoelectric material, a first positive internal electrode provided in the first piezoelectric layer, and No. 1 The first positive internal electrode is provided in the piezoelectric layer and is connected to the first positive internal electrode via the first piezoelectric layer. In the second direction and a first negative electrode internal electrode facing each other, and when a voltage is applied between the first positive electrode internal electrode and the first negative electrode internal electrode, the first positive electrode internal electrode and the first negative electrode internal electrode expand and contract along a first direction parallel to the electrode surfaces of the first positive electrode internal electrode and the first negative electrode internal electrode. The second piezoelectric actuator is laminated on the first piezoelectric actuator and includes a second piezoelectric layer made of a piezoelectric material, a second positive electrode internal electrode provided in the second piezoelectric layer, and a second positive electrode internal electrode provided in the second piezoelectric layer and connected to the second positive electrode via the second piezoelectric layer. In the second direction above and a second negative electrode internal electrode facing each other, and when a voltage is applied between the second positive electrode internal electrode and the second negative electrode internal electrode, a voltage perpendicular to the electrode surfaces of the second positive electrode internal electrode and the second negative electrode internal electrode is applied. The above stretches along the second direction. [Effects of the Invention]

[0018] As described above, according to the present invention, it is possible to provide a vibration generating device and an electronic device that are capable of producing a variety of tactile sensations through vibration. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a perspective view of a vibration generator according to a first embodiment of the present invention. [Figure 2] FIG. 2 is an exploded perspective view of the vibration generator. [Figure 3] FIG. 2 is a perspective view of a first piezoelectric actuator included in the vibration generator. [Figure 4] FIG. 3 is a plan view of the first piezoelectric actuator. [Figure 5] FIG. 3 is a cross-sectional view of the first piezoelectric actuator. [Figure 6] 4 is a schematic diagram showing the arrangement of a first positive internal electrode of the first piezoelectric actuator. FIG. [Figure 7] 4 is a schematic diagram showing the arrangement of a first negative internal electrode of the first piezoelectric actuator. FIG. [Figure 8] FIG. 2 is a perspective view of a first end surface of the first piezoelectric actuator. [Figure 9] FIG. 4 is a perspective view of a second end surface of the first piezoelectric actuator. [Figure 10] 5A to 5C are schematic diagrams showing the operation of the first piezoelectric actuator. [Figure 11] FIG. 4 is a perspective view of a second piezoelectric actuator included in the vibration generator. [Figure 12] FIG. 4 is a plan view of the second piezoelectric actuator. [Figure 13] FIG. 3 is a cross-sectional view of the second piezoelectric actuator. [Figure 14] 5 is a schematic diagram showing the arrangement of a second positive internal electrode of the second piezoelectric actuator. FIG. [Figure 15] 5 is a schematic diagram showing the arrangement of a second negative internal electrode of the second piezoelectric actuator. FIG. [Figure 16] FIG. 10 is a perspective view of a seventh end surface of the second piezoelectric actuator. [Figure 17] FIG. 10 is a perspective view of an eighth end surface of the second piezoelectric actuator. [Figure 18] 5A to 5C are schematic diagrams illustrating the operation of the second piezoelectric actuator. [Figure 19] FIG. 2 is a plan view of the vibration generator. [Figure 20] FIG. 2 is a plan view of the vibration generator. [Figure 21] FIG. 2 is a plan view of the vibration generator. [Figure 22] FIG. 2 is a plan view of the vibration generator. [Figure 23] FIG. 2 is a plan view of the vibration generator. [Figure 24] FIG. 2 is a perspective view of the vibration generating device. [Figure 25] FIG. 2 is a perspective view of the vibration generating device. [Figure 26] FIG. 2 is a perspective view showing a positive external electrode of the vibration generator. [Figure 27] FIG. 2 is a perspective view showing a negative external electrode of the vibration generator. [Figure 28] 3 is a perspective view showing a first positive external electrode and a second positive external electrode of the vibration generator. FIG. [Figure 29] 3 is a perspective view showing a first negative external electrode and a second negative external electrode of the vibration generator. FIG. [Figure 30] This is a high-frequency waveform generated by a driving unit included in the vibration generator. [Figure 31] This is a low frequency waveform generated by the drive unit. [Figure 32] This is the amplitude modulated waveform generated by the drive unit. [Figure 33] This is an enlarged waveform of the amplitude modulated wave in FIG. [Figure 34] This is an amplitude modulated waveform (voltage waveform only) generated by the driving unit. [Figure 35] This is an enlarged waveform of the amplitude modulated wave in FIG. [Figure 36] FIG. 2 is a schematic diagram showing the amplitude of an amplitude-modulated wave. [Figure 37] FIG. 2 is a perspective view showing a mounting structure of the vibration generator. [Figure 38] FIG. 2 is a plan view showing a mounting structure of the vibration generator. [Figure 39] FIG. 10 is a perspective view of a vibration generator according to a second embodiment of the present invention. [Figure 40] FIG. 2 is an exploded perspective view of the vibration generator. [Figure 41] FIG. 4 is a perspective view of a second piezoelectric actuator included in the vibration generator. [Figure 42] FIG. 4 is a plan view of the second piezoelectric actuator. [Figure 43] FIG. 3 is a cross-sectional view of the second piezoelectric actuator. [Figure 44] 5 is a schematic diagram showing the arrangement of a second positive internal electrode of the second piezoelectric actuator. FIG. [Figure 45]5 is a schematic diagram showing the arrangement of a second negative internal electrode of the second piezoelectric actuator. FIG. [Figure 46] FIG. 10 is a perspective view of a seventh end surface of the second piezoelectric actuator. [Figure 47] FIG. 10 is a perspective view of an eighth end surface of the second piezoelectric actuator. [Figure 48] 5A to 5C are schematic diagrams illustrating the operation of the second piezoelectric actuator. [Figure 49] FIG. 2 is a plan view of the vibration generator. [Figure 50] FIG. 2 is a plan view of the vibration generator. [Figure 51] FIG. 2 is a plan view of the vibration generator. [Figure 52] FIG. 2 is a plan view of the vibration generator. [Figure 53] FIG. 2 is a plan view of the vibration generator. [Figure 54] FIG. 2 is a perspective view of the vibration generating device. [Figure 55] FIG. 2 is a perspective view of the vibration generating device. [Figure 56] FIG. 2 is a perspective view showing a positive external electrode of the vibration generator. [Figure 57] FIG. 2 is a perspective view showing a negative external electrode of the vibration generator. [Figure 58] 3 is a perspective view showing a first positive external electrode and a second positive external electrode of the vibration generator. FIG. [Figure 59] 3 is a perspective view showing a first negative external electrode and a second negative external electrode of the vibration generator. FIG. [Figure 60] FIG. 2 is a perspective view showing a mounting structure of the vibration generator. [Figure 61] FIG. 2 is a plan view showing a mounting structure of the vibration generator. DETAILED DESCRIPTION OF THE INVENTION

[0020] (First embodiment) A vibration generator according to a first embodiment of the present invention will be described.

[0021] [Configuration of vibration generator] Fig. 1 is a perspective view of a vibration exciter 100 according to this embodiment, and Fig. 2 is an exploded perspective view of the vibration exciter 100. In each drawing of this disclosure, the longitudinal direction of the vibration exciter 100 is defined as the X direction, the lateral direction as the Y direction, and the thickness direction as the Z direction.

[0022] As shown in Figures 1 and 2, the vibration generator 100 includes one first piezoelectric actuator 110 and multiple second piezoelectric actuators 120, with the multiple second piezoelectric actuators 120 stacked on the single first piezoelectric actuator 110.

[0023] FIG. 3 is a perspective view of the first piezoelectric actuator 110, and FIG. 4 is a plan view of the first piezoelectric actuator 110. As shown in FIGS. 3 and 4, the first piezoelectric actuator 110 has a flat plate shape with its main surface parallel to the XY plane, its longitudinal direction in the X direction, and its lateral direction in the Y direction. Hereinafter, the main surface of the first piezoelectric actuator 110 facing the second piezoelectric actuator 120 will be referred to as the first main surface 110a, and the main surface opposite the first main surface 110a will be referred to as the second main surface 110b. Furthermore, if the X direction is referred to as the "first direction" and the Z direction is referred to as the "second direction," then one end surface perpendicular to the first direction and parallel to the second direction will be referred to as the first end surface 110c, and the end surface perpendicular to the first direction, parallel to the second direction, and opposite the first end surface 110c will be referred to as the second end surface 110d. Furthermore, one end face parallel to the first direction and the second direction is a third end face 110e, and the end face parallel to the first direction and the second direction and opposite to the third end face 110e is a fourth end face 110f.

[0024] Fig. 5 is a cross-sectional view of the first piezoelectric actuator 110, taken along line AA in Fig. 4. As shown in the figure, the first piezoelectric actuator 110 includes a first piezoelectric layer 111, a first positive internal electrode 112, and a first negative internal electrode 113. The first piezoelectric layer 111 is made of a piezoelectric material such as PZT (lead zirconate titanate).

[0025] The first positive internal electrode 112 is made of a conductive material, is provided in the first piezoelectric layer 111, and faces the first negative internal electrode 113 via the first piezoelectric layer 111. The first positive internal electrode 112 is flat, and when the main surface of the first positive internal electrode 112 is taken as the electrode surface, the electrode surface is parallel to the first main surface 110a and the second main surface 110b (XY plane), that is, parallel to the first direction (X direction). As shown in FIG. 5, five first positive internal electrodes 112 may be provided, or four or less or six or more may be provided.

[0026] 6 is a schematic diagram showing the arrangement of the first positive internal electrode 112 in the first piezoelectric actuator 110. As shown in the figure, one side of the first positive internal electrode 112 coincides with the first end face 110c, and the other peripheral edge is arranged spaced apart from the second end face 110d, the third end face 110e, and the fourth end face 110f.

[0027] The first negative electrode internal electrode 113 is made of a conductive material, is provided in the first piezoelectric layer 111, and faces the first positive electrode internal electrode 112 via the first piezoelectric layer 111. The first negative electrode internal electrode 113 is flat, and when the main surface of the first negative electrode internal electrode 113 is taken as the electrode surface, the electrode surface is parallel to the first main surface 110a and the second main surface 110b (XY plane), that is, parallel to the first direction (X direction). As shown in FIG. 5, five first negative electrode internal electrodes 113 may be provided, or four or less or six or more may be provided.

[0028] 7 is a schematic diagram showing the arrangement of the first negative internal electrode 113 in the first piezoelectric actuator 110. As shown in the figure, one side of the first negative internal electrode 113 coincides with the second end face 110d, and the other peripheral edge is arranged spaced apart from the first end face 110c, the third end face 110e, and the fourth end face 110f.

[0029] Fig. 8 is a perspective view showing the first end surface 110c. As shown in the figure, an end of the first positive internal electrode 112 is exposed at the first end surface 110c, but the first negative internal electrode 113 is not exposed. Fig. 9 is a perspective view showing the second end surface 110d. As shown in the figure, an end of the first negative internal electrode 113 is exposed at the second end surface 110d, but the first positive internal electrode 112 is not exposed.

[0030] The first piezoelectric actuator 110 has such a configuration. Fig. 10 is a schematic diagram showing vibration of the first piezoelectric actuator 110. When a voltage is applied between the first positive internal electrode 112 and the first negative internal electrode 113, the first piezoelectric actuator 110 expands and contracts (indicated by arrows in the figure) along a first direction (X direction) parallel to the electrode surfaces of the first positive internal electrode 112 and the first negative internal electrode 113 due to the inverse piezoelectric effect in the first piezoelectric layer 111, thereby generating vibration. Such expansion and contraction is called the d31 mode, and the first piezoelectric actuator 110 is a piezoelectric actuator that vibrates in the d31 mode.

[0031] FIG. 11 is a perspective view of the second piezoelectric actuator 120, and FIG. 12 is a plan view of the second piezoelectric actuator 120. As shown in FIGS. 11 and 12, the second piezoelectric actuator 120 has a flat plate shape with its main surface parallel to the XY plane, its short side in the X direction, and its long side in the Y direction. Hereinafter, of the main surfaces of the second piezoelectric actuator 120, the main surface facing the first piezoelectric actuator 110 will be referred to as a third main surface 120a, and the main surface opposite to the third main surface 120a will be referred to as a fourth main surface 120b. Furthermore, one end surface perpendicular to the first direction (X direction) and parallel to the second direction (Z direction) will be referred to as a fifth end surface 120c, and the end surface perpendicular to the first direction, parallel to the second direction, and opposite to the fifth end surface 120c will be referred to as a sixth end surface 120d. Furthermore, one end face parallel to the first direction and the second direction is a seventh end face 120e, and the end face parallel to the first direction and the second direction and opposite to the seventh end face 120e is an eighth end face 120f.

[0032] Fig. 13 is a cross-sectional view of the second piezoelectric actuator 120, taken along line BB in Fig. 12. As shown in the figure, the second piezoelectric actuator 120 includes a second piezoelectric layer 121, a second positive internal electrode 122, and a second negative internal electrode 123. The second piezoelectric layer 121 is made of a piezoelectric material such as PZT (lead zirconate titanate).

[0033] The second positive electrode internal electrode 122 is made of a conductive material, is provided in the second piezoelectric layer 121, and faces the second negative electrode internal electrode 123 via the second piezoelectric layer 121. The second positive electrode internal electrode 122 is flat, and when the main surface of the second positive electrode internal electrode 122 is taken as the electrode surface, the electrode surface is parallel to the third main surface 120a and the fourth main surface 120b (XY plane), that is, parallel to the first direction (X direction). As shown in FIG. 13 , five second positive electrode internal electrodes 122 may be provided, or four or less or six or more may be provided.

[0034] 14 is a schematic diagram showing the arrangement of the second positive internal electrode 122 in the second piezoelectric actuator 120. As shown in the figure, one side of the second positive internal electrode 122 coincides with the seventh end face 120e, and the other peripheral edge is arranged spaced apart from the fifth end face 120c, the sixth end face 120d, and the eighth end face 120f.

[0035] The second negative electrode internal electrode 123 is made of a conductive material, is provided in the second piezoelectric layer 121, and faces the second positive electrode internal electrode 122 via the second piezoelectric layer 121. The second negative electrode internal electrode 123 is flat, and when the main surface of the second negative electrode internal electrode 123 is taken as the electrode surface, the electrode surface is parallel to the third main surface 120a and the fourth main surface 120b (XY plane), that is, parallel to the first direction (X direction). As shown in FIG. 13 , five second negative electrode internal electrodes 123 may be provided, or four or less or six or more may be provided.

[0036] 15 is a schematic diagram showing the arrangement of the second negative internal electrode 123 in the second piezoelectric actuator 120. As shown in the figure, one side of the second negative internal electrode 123 coincides with the eighth end face 120f, and the other peripheral edge is arranged spaced apart from the fifth end face 120c, the sixth end face 120d, and the seventh end face 120e.

[0037] Fig. 16 is a perspective view showing the seventh end surface 120e. As shown in the figure, an end of the second positive electrode internal electrode 122 is exposed at the seventh end surface 120e, but the second negative electrode internal electrode 123 is not exposed. Fig. 17 is a perspective view showing the eighth end surface 120f. As shown in the figure, an end of the second negative electrode internal electrode 123 is exposed at the eighth end surface 120f, but the second positive electrode internal electrode 122 is not exposed.

[0038] The second piezoelectric actuator 120 has such a configuration. Fig. 18 is a schematic diagram showing vibration of the second piezoelectric actuator 120. When a voltage is applied between the second positive internal electrode 122 and the second negative internal electrode 123, the second piezoelectric actuator 120 expands and contracts (indicated by arrows in the figure) along a second direction (Z direction) perpendicular to the electrode surfaces of the second positive internal electrode 122 and the second negative internal electrode 123 due to the inverse piezoelectric effect in the second piezoelectric layer 121, thereby generating vibration. Such expansion and contraction is called the d33 mode, and the second piezoelectric actuator 120 is a piezoelectric actuator that vibrates in the d33 mode.

[0039] [Positional relationship between the first and second piezoelectric actuators] The positional relationship between the first piezoelectric actuator 110 and the second piezoelectric actuator 120 will be described below. Figures 19 to 23 are plan views of the vibration generator 100 as viewed from various directions. As shown in Figures 19 to 21, the second piezoelectric actuators 120 are arranged in a row on the first piezoelectric actuator 110 along the first direction (X direction) with their short sides oriented in the same direction. As a result, as shown in Figures 22 and 23, the seventh end face 120e of the second piezoelectric actuator 120 is continuous with the third end face 110e of the first piezoelectric actuator 110, and the eighth end face 120f of the second piezoelectric actuator 120 is continuous with the fourth end face 110f of the first piezoelectric actuator 110.

[0040] Fig. 24 is a perspective view of the vibration generator 100 seen from the first end face 110c and seventh end face 120e side. As shown in the figure, the first positive electrode internal electrode 112 is exposed at the first end face 110c, and the second positive electrode internal electrode 122 is exposed at the seventh end face 120e. Fig. 25 is a perspective view of the vibration generator 100 seen from the second end face 110d and eighth end face 120f side. As shown in the figure, the first negative electrode internal electrode 113 is exposed at the second end face 110d, and the second negative electrode internal electrode 123 is exposed at the eighth end face 120f.

[0041] [About the common external electrode] The vibration generator 100 may include a positive external electrode and a negative external electrode connected to both the first piezoelectric actuator 110 and the second piezoelectric actuator 120. FIG. 26 is a schematic diagram showing a positive external electrode 131. The positive external electrode 131 is made of a conductive material and is formed on the first end face 110c, the third end face 110e, and the seventh end face 120e (see FIG. 24). As described above, the first positive internal electrode 112 is exposed on the first end face 110c, and the second positive internal electrode 122 is exposed on the seventh end face 120e, so that the positive external electrode 131 is electrically connected to the first positive internal electrode 112 and the second positive internal electrode 122.

[0042] 27 is a schematic diagram showing the negative external electrode 132. The negative external electrode 132 is made of a conductive material, and is formed on the second end face 110d, the fourth end face 110f, and the eighth end face 120f (see FIG. 25). As described above, the first negative internal electrode 113 is exposed at the second end face 110d, and the second negative internal electrode 123 is exposed at the eighth end face 120f, so the negative external electrode 132 is electrically connected to the first negative internal electrode 113 and the second negative internal electrode 123.

[0043] The positive external electrode 131 and the negative external electrode 132 are connected to a drive unit (not shown), and a drive signal output from the drive unit is transmitted to the first positive internal electrode 112, the first negative internal electrode 113, the second positive internal electrode 122, and the second negative internal electrode 123. In this configuration, the positive external electrode 131 and the negative external electrode 132 are common to the first piezoelectric actuator 110 and the second piezoelectric actuator 120, and therefore the same drive signal is supplied to the first piezoelectric actuator 110 and the second piezoelectric actuator 120.

[0044] [Independent external electrodes] The vibration generator 100 may also include two positive external electrodes and two negative external electrodes connected to the first piezoelectric actuator 110 and the second piezoelectric actuator 120, respectively.

[0045] 28 is a schematic diagram showing a first positive external electrode 141 and a second positive external electrode 151. The first positive external electrode 141 is made of a conductive material and is formed on the first end surface 110c (see FIG. 24). As described above, the first positive internal electrode 112 is exposed on the first end surface 110c, and therefore the first positive external electrode 141 is electrically connected to the first positive internal electrode 112. The second positive external electrode 151 is made of a conductive material and is formed on the third end surface 110e and the seventh end surface 120e (see FIG. 24). As described above, the second positive internal electrode 122 is exposed on the seventh end surface 120e, and therefore the second positive external electrode 151 is electrically connected to the second positive internal electrode 122.

[0046] 29 is a schematic diagram showing the first negative external electrode 142 and the second negative external electrode 152. The first negative external electrode 142 is made of a conductive material and is formed on the second end surface 110d (see FIG. 25). As described above, the first negative internal electrode 113 is exposed on the second end surface 110d, so the first negative external electrode 142 is electrically connected to the first negative internal electrode 113. The second negative external electrode 152 is made of a conductive material and is formed on the fourth end surface 110f and the eighth end surface 120f (see FIG. 25). As described above, the second negative internal electrode 123 is exposed on the eighth end surface 120f, so the second negative external electrode 152 is electrically connected to the second negative internal electrode 123.

[0047] The first positive external electrode 141, the first negative external electrode 142, the second positive external electrode 151, and the second negative external electrode 152 are connected to a driving unit (not shown). The first positive external electrode 141 and the first negative external electrode 142 transmit a driving signal output from the driving unit to the first positive internal electrode 112 and the first negative internal electrode 113. The second positive external electrode 151 and the second negative external electrode 152 transmit a driving signal output from the driving unit to the second positive internal electrode 122 and the second negative internal electrode 123.

[0048] In this configuration, the first positive external electrode 141 and the first negative external electrode 142 function as external electrodes for the first piezoelectric actuator 110, and the second positive external electrode 151 and the second negative external electrode 152 function as external electrodes for the second piezoelectric actuator 120. This makes it possible to supply different drive signals to the first piezoelectric actuator 110 and the second piezoelectric actuator 120. Note that one of the positive and negative electrodes may be a common external electrode and the other an independent external electrode, and it is also possible to configure the first positive external electrode 141 and the second positive external electrode 151 to be electrically connected, or the first negative external electrode 142 and the second negative external electrode 152 to be electrically connected.

[0049] [Drive signal for the first piezoelectric actuator] A description will now be given of the waveform of the drive signal output from the drive unit to the first piezoelectric actuator 110. Note that, for the sake of convenience, the signal wave in the low frequency range is assumed to be a sine wave in the following description, but is not limited to this.

[0050] Figure 30 shows voltage waveforms and current waveforms that are sine waves in the high frequency range, with frequencies between 20 kHz and 100 kHz. When the voltage waveform shown in Figure 30 is applied as a drive signal from the drive unit to first piezoelectric actuator 110, a current having the current waveform shown in Figure 30 flows. Vibrations in the high frequency range between 20 kHz and 100 kHz are vibrations that cause the floating phenomenon.

[0051] Figure 31 shows voltage waveforms and current waveforms that are sine waves in the low-frequency range, with frequencies between 1 Hz and 250 Hz. When the voltage waveform shown in Figure 31 is applied as a drive signal from the drive unit to first piezoelectric actuator 110, a current having the current waveform shown in Figure 31 flows. Vibrations in the low-frequency range between 1 Hz and 250 Hz are vibrations that can be sensitively sensed by receptors in the human skin, such as Meissner's corpuscles and Pacinian corpuscles.

[0052] Fig. 32 shows voltage and current waveforms having an amplitude-modulated waveform in which a sine wave (signal wave) in the low frequency domain is used as a modulating wave and a sine wave in the high frequency domain is amplitude-modulated by this modulating wave. Fig. 33 is an enlarged view of Fig. 32. When the voltage waveform shown in Fig. 32 is applied as a drive signal from the drive unit to first piezoelectric actuator 110, a current having the current waveform shown in Fig. 32 flows.

[0053] Figure 34 shows only the voltage waveform of Figure 32, and Figure 35 shows only the voltage waveform of Figure 33. In Figures 34 and 35, the wave with a small wavelength indicated by W1 is a sine wave in the high frequency region, and the wave with a large wavelength indicated by W2 is a sine wave in the low frequency region. Hereinafter, the sine wave in the high frequency region will be referred to as high frequency W1, and the sine wave in the low frequency region will be referred to as low frequency W2.

[0054] In the waveforms shown in Figures 34 and 35, the low frequency W2 is formed by changing the amplitude of the high frequency W1, that is, the waveforms shown in Figures 34 and 35 are amplitude-modulated waves with the high frequency W1 as the carrier wave and the low frequency W2 as the modulating wave. Note that the high frequency W1 has a frequency of 20 kHz or more and 100 kHz or less, and the low frequency W2 has a frequency of 1 Hz or more and 250 Hz or less.

[0055] The voltage gain of the high frequency W1 is preferably between -10 dB and 0 dB, and the voltage gain of the low frequency W2 is preferably between -6 dB and 0 dB. Figure 36 is a schematic diagram showing the relationship between the waveform of an amplitude-modulated wave and the voltage gain. As shown in the figure, if the amplitude of the "peak" of the amplitude-modulated wave is amplitude a and the amplitude of the "valley" is amplitude b, then the modulation depth m is expressed by the following (Equation 1). As shown in the following (Equation 1), the smaller the amplitude b is relative to the amplitude a, the greater the modulation depth m.

[0056] m=(ab) / (a+b) (Equation 1)

[0057] In Figure 36, as shown by the white arrow in Figure 34, when the voltage gain of low frequency W2 is increased, the "valley bottom" of low frequency W2 becomes deeper, and when the voltage gain of low frequency W2 is 0 dB, the amplitude of the "valley bottom" is minimized. Furthermore, when the voltage gain of low frequency W2 is reduced, approaching -6 dB, the "valley bottom" of low frequency W2 becomes shallower and the amplitude increases. Furthermore, when the voltage gain of low frequency W2 is reduced, approaching -10 dB, the amplitude b of the "valley bottom" of low frequency W2 becomes equal to the amplitude of the "peak," and no "valley" is formed.

[0058] In this embodiment, the voltage gains of the high frequency W1 and the low frequency W2 are adjusted to a range in which a "valley" is formed. Specifically, the voltage gain of the high frequency W1 is preferably between -10 dB and 0 dB, and the voltage gain of the low frequency W2 is preferably between -6 dB and 0 dB. Furthermore, the voltage gain of the high frequency W1 is more preferably -10 dB, and the voltage gain of the low frequency W2 is more preferably 0 dB.

[0059] [Drive signal for the second piezoelectric actuator] A description will now be given of the waveform of the drive signal output from the drive unit to the second piezoelectric actuator 120. Note that, for the sake of convenience, the signal wave in the low frequency range is assumed to be a sine wave in the following description, but is not limited to this.

[0060] When the first piezoelectric actuator 110 and the second piezoelectric actuator 120 share a common external electrode (see FIGS. 26 and 27), the same drive signal is supplied from the drive unit to the first piezoelectric actuator 110 and the second piezoelectric actuator 120. That is, an amplitude-modulated wave (see FIGS. 34 and 35) with high frequency W1 as the carrier wave and low frequency W2 as the modulating wave is also supplied to the second piezoelectric actuator 120.

[0061] When the external electrodes of the first piezoelectric actuator 110 and the second piezoelectric actuator 120 are independent (see FIGS. 28 and 29), it is possible to supply a different drive signal to the second piezoelectric actuator 120 than to the first piezoelectric actuator 110. Specifically, the drive unit can supply an amplitude-modulated wave, with a first low frequency as the carrier wave and a second low frequency as the modulating wave, to the second piezoelectric actuator 120. The first low frequency is preferably 110 Hz or more and 250 Hz or less, and the second low frequency is preferably 1 Hz or more and 50 Hz or less.

[0062] [About the mounting structure of the vibration generator] The mounting structure of the electromagnetic exciter 100 will now be described. The electromagnetic exciter 100 can be bonded to a vibrating member. FIG. 37 is a perspective view of the electromagnetic exciter 100 bonded to a vibrating member 180, and FIG. 38 is a plan view of the electromagnetic exciter 100 bonded to the vibrating member 180. The vibrating member 180 is a member to which vibrations from the electromagnetic exciter 100 are transmitted, and may be, for example, a display panel, a trackpad, or the housing of an electronic device. As shown in FIG. 38, the vibrating member 180 is bonded to the fourth main surface 120b of the second piezoelectric actuator 120. As shown in FIG. 37, two electromagnetic exciters 100 may be bonded to both ends of the vibrating member 180, or one or three or more electromagnetic exciters 100 may be bonded to the vibrating member 180. Alternatively, the electromagnetic exciter 100 may be disposed in the center of a mouse or the like so that the user can directly touch the fourth main surface 120b.

[0063] [Effects of vibration generator] As described above, the vibration generator 100 is configured by stacking the first piezoelectric actuator 110 that vibrates in the d31 mode and the second piezoelectric actuator 120 that vibrates in the d33 mode. Therefore, the first piezoelectric actuator 110 in the d31 mode can express vibrations in the force feedback region (low frequency region), and the second piezoelectric actuator 120 in the d33 mode can express high frequency levitation vibrations. Furthermore, by generating high frequency vibrations in the first piezoelectric actuator 110, the protruding shape of the second piezoelectric actuator 120 contributes, making it possible to express fine levitation vibrations.

[0064] Furthermore, in the vibration generator 100, the drive unit can output a drive signal having an amplitude-modulated voltage waveform as shown in Fig. 34 to the first piezoelectric actuator 110. This amplitude-modulated wave is obtained by amplitude-modulating a high frequency W1 that causes a levitation phenomenon with a low frequency W2 that can be sensitively sensed by receptors in the human skin, such as Meissner's corpuscles and Pacinian corpuscles. Therefore, when a user places their finger in contact with the fourth main surface 120b or the vibrating member 180, a delicate tactile sensation can be presented to the user's finger in a realistic manner. Furthermore, the tactile sensation can be enhanced by moving the finger while it is in contact.

[0065] Furthermore, because the high frequency W1 is amplitude modulated, the average current of the entire waveform is smaller than when it is not amplitude modulated, making it possible to reduce power consumption and heat generation. In particular, when the voltage gain of the high frequency W1 is set to between -10 dB and 0 dB and the voltage gain of the low frequency W2 is set to between -6 dB and 0 dB, a "valley" (white arrow in Figure 34) is formed, making it possible to reduce power consumption and heat generation. Furthermore, when the voltage gain of the high frequency W1 is set to -10 dB and the voltage gain of the low frequency W2 is set to 0 dB, the "valley" becomes deepest, making it possible to minimize power consumption and heat generation. In addition, amplitude-modulated waves can also suppress the generation of abnormal noise associated with the levitation phenomenon.

[0066] [Method of manufacturing the vibration generating device] The electromagnetic exciter 100 can be manufactured as follows. First, the first piezoelectric layer 111, the first positive internal electrode 112, and the first negative internal electrode 113 (see FIG. 5) are laminated, and then the second piezoelectric layer 121, the second positive internal electrode 122, and the second negative internal electrode 123 (see FIG. 13) are laminated thereon. This laminate is heated to sinter the first piezoelectric layer 111 and the second piezoelectric layer 121. Next, the second piezoelectric layer 121, the second positive internal electrode 122, and the second negative internal electrode 123 are cut to form multiple second piezoelectric actuators 120 (see FIG. 2). This results in the electromagnetic exciter 100, in which multiple second piezoelectric actuators 120 are laminated on one first piezoelectric actuator 110. In this way, the electromagnetic exciter 100 can be manufactured by a single sintering process. However, the electromagnetic exciter 100 can also be manufactured by other manufacturing methods.

[0067] (Second embodiment) A vibration generator according to a second embodiment of the present invention will now be described.

[0068] [Configuration of vibration generator] FIG. 39 is a perspective view of a vibration exciter 200 according to this embodiment, and FIG. 40 is an exploded perspective view of the vibration exciter 200. As shown in FIG.

[0069] 39 and 40, the vibration generator 200 includes one first piezoelectric actuator 110 and multiple second piezoelectric actuators 220, with the multiple second piezoelectric actuators 220 stacked on the single first piezoelectric actuator 110. Since the first piezoelectric actuator 110 has the same configuration as in the first embodiment, it is denoted by the same reference numerals as in the first embodiment and a description thereof will be omitted.

[0070] FIG. 41 is a perspective view of second piezoelectric actuator 220, and FIG. 42 is a plan view of second piezoelectric actuator 220. As shown in FIGS. 41 and 42, second piezoelectric actuator 220 has a main surface parallel to the XY plane and a flat plate shape with the same length in the X and Y directions. Hereinafter, of the main surfaces of second piezoelectric actuator 220, the main surface facing first piezoelectric actuator 110 will be referred to as third main surface 220a, and the main surface opposite third main surface 220a will be referred to as fourth main surface 220b. Furthermore, one end surface perpendicular to the first direction (X direction) and parallel to the second direction (Z direction) will be referred to as fifth end surface 220c, and the end surface perpendicular to the first direction, parallel to the second direction, and opposite fifth end surface 220c will be referred to as sixth end surface 220d. Furthermore, one end face parallel to the first direction and the second direction is a seventh end face 220e, and the end face parallel to the first direction and the second direction and opposite to the seventh end face 220e is an eighth end face 220f.

[0071] Fig. 43 is a cross-sectional view of the second piezoelectric actuator 120, taken along line CC in Fig. 42. As shown in the figure, the second piezoelectric actuator 220 includes a second piezoelectric layer 221, a second positive internal electrode 222, and a second negative internal electrode 223. The second piezoelectric layer 221 is made of a piezoelectric material such as PZT (lead zirconate titanate).

[0072] The second positive electrode internal electrode 222 is made of a conductive material, is provided in the second piezoelectric layer 221, and faces the second negative electrode internal electrode 223 via the second piezoelectric layer 221. The second positive electrode internal electrode 222 is flat, and when the main surface of the second positive electrode internal electrode 222 is taken as the electrode surface, the electrode surface is parallel to the third main surface 220a and the fourth main surface 220b (XY plane), that is, parallel to the first direction (X direction). As shown in FIG. 43 , five second positive electrode internal electrodes 222 may be provided, or four or less or six or more may be provided.

[0073] 44 is a schematic diagram showing the arrangement of the second positive internal electrode 222 in the second piezoelectric actuator 220. As shown in the figure, one side of the second positive internal electrode 222 coincides with the seventh end face 220e, and the other peripheral edge is arranged spaced apart from the fifth end face 220c, the sixth end face 220d, and the eighth end face 220f.

[0074] The second negative electrode internal electrode 223 is made of a conductive material, is provided in the second piezoelectric layer 221, and faces the second positive electrode internal electrode 222 via the second piezoelectric layer 221. The second negative electrode internal electrode 223 is flat, and when the main surface of the second negative electrode internal electrode 223 is taken as the electrode surface, the electrode surface is parallel to the third main surface 220a and the fourth main surface 220b (XY plane), that is, parallel to the first direction (X direction). As shown in FIG. 43 , five second negative electrode internal electrodes 223 may be provided, or four or less or six or more may be provided.

[0075] 45 is a schematic diagram showing the arrangement of the second negative electrode internal electrode 223 in the second piezoelectric actuator 220. As shown in the figure, one side of the second negative electrode internal electrode 223 coincides with the eighth end face 220f, and the other peripheral edge is arranged spaced apart from the fifth end face 220c, the sixth end face 220d, and the seventh end face 220f.

[0076] Fig. 46 is a perspective view showing the seventh end surface 220e. As shown in the figure, an end of the second positive electrode internal electrode 222 is exposed at the seventh end surface 220e, but the second negative electrode internal electrode 223 is not exposed. Fig. 47 is a perspective view showing the eighth end surface 220f. As shown in the figure, an end of the second negative electrode internal electrode 223 is exposed at the eighth end surface 220f, but the second positive electrode internal electrode 222 is not exposed.

[0077] The second piezoelectric actuator 220 has such a configuration. Fig. 48 is a schematic diagram showing vibration of the second piezoelectric actuator 220. When a voltage is applied between the second positive electrode internal electrode 222 and the second negative electrode internal electrode 223, the second piezoelectric actuator 220 expands and contracts (indicated by arrows in the figure) along a second direction (Z direction) perpendicular to the electrode surfaces of the second positive electrode internal electrode 222 and the second negative electrode internal electrode 223 due to the inverse piezoelectric effect in the second piezoelectric layer 221, thereby generating vibration. Such expansion and contraction is called the d33 mode, and the second piezoelectric actuator 220 is a piezoelectric actuator that vibrates in the d33 mode.

[0078] [Positional relationship between the first and second piezoelectric actuators] The positional relationship between the first piezoelectric actuator 110 and the second piezoelectric actuator 220 will be described below. Figures 49 to 53 are plan views of the vibration generator 200 viewed from various directions. As shown in Figures 49 to 51, the second piezoelectric actuators 220 are arranged in two rows on the first piezoelectric actuator 110 along the first direction (X direction) with their eighth end faces 220f facing outward. As a result, as shown in Figures 52 and 53, the seventh end face 220e of one second piezoelectric actuator 220 faces the seventh end face 220e of the adjacent second piezoelectric actuator 220, and the eighth end face 220f is continuous with the third end face 110e and the fourth end face 110f of the first piezoelectric actuator 110.

[0079] Fig. 54 is a perspective view of the vibration generator 200 seen from the first end face 110c and third end face 110e side. As shown in the figure, the first positive electrode internal electrode 112 is exposed at the first end face 110c, and the second negative electrode internal electrode 223 is exposed at the eighth end face 220f. Fig. 55 is a perspective view of the vibration generator 200 seen from the second end face 110d and fourth end face 110f side. As shown in the figure, the first negative electrode internal electrode 113 is exposed at the second end face 110d, and the second negative electrode internal electrode 223 is exposed at the eighth end face 220f.

[0080] Furthermore, as shown in FIGS. 54 and 55, seventh end faces 220e face each other between the rows of the second piezoelectric actuators 220, and the second positive internal electrodes 222 are exposed to the seventh end faces 220e.

[0081] [About the common external electrode] The vibration generator 200 can include a positive external electrode and a negative external electrode connected to both the first piezoelectric actuator 110 and the second piezoelectric actuator 220. Fig. 56 is a schematic diagram showing a positive external electrode 231. The positive external electrode 231 is made of a conductive material and is formed on the first end face 110c and the seventh end face 220e (see Fig. 54). As described above, the first positive internal electrode 112 is exposed on the first end face 110c, and the second positive internal electrode 222 is exposed on the seventh end face 220e, so that the positive external electrode 231 is electrically connected to the first positive internal electrode 112 and the second positive internal electrode 222.

[0082] 57 is a schematic diagram showing the negative external electrode 232. The negative external electrode 232 is made of a conductive material, and is formed on the second end face 110d and the eighth end face 220f (see FIG. 55). As described above, the first negative internal electrode 113 is exposed at the second end face 110d, and the second negative internal electrode 223 is exposed at the eighth end face 220f, so the negative external electrode 232 is electrically connected to the first negative internal electrode 113 and the second negative internal electrode 223.

[0083] The positive external electrode 231 and the negative external electrode 232 are connected to a drive unit (not shown), and a drive signal output from the drive unit is transmitted to the first positive internal electrode 112, the first negative internal electrode 113, the second positive internal electrode 222, and the second negative internal electrode 223. In this configuration, the positive external electrode 231 and the negative external electrode 232 are common to the first piezoelectric actuator 110 and the second piezoelectric actuator 220, and therefore the same drive signal is supplied to the first piezoelectric actuator 110 and the second piezoelectric actuator 220.

[0084] [Independent external electrodes] The vibration generator 200 may also include two positive external electrodes and two negative external electrodes connected to the first piezoelectric actuator 110 and the second piezoelectric actuator 220, respectively.

[0085] 58 is a schematic diagram showing the first positive external electrode 241 and the second positive external electrode 251. The first positive external electrode 241 is made of a conductive material and is formed on the first end surface 110c (see FIG. 54). As described above, the first positive internal electrode 112 is exposed at the first end surface 110c, and therefore the first positive external electrode 241 is electrically connected to the first positive internal electrode 112. The second positive external electrode 251 is made of a conductive material and is formed on the seventh end surface 220e (see FIG. 54). As described above, the second positive internal electrode 222 is exposed at the seventh end surface 220e, and therefore the second positive external electrode 251 is electrically connected to the second positive internal electrode 222.

[0086] 59 is a schematic diagram showing the first negative external electrode 242 and the second negative external electrode 252. The first negative external electrode 242 is made of a conductive material and is formed on the second end surface 110d (see FIG. 55). As described above, the first negative internal electrode 113 is exposed at the second end surface 110d, and therefore the first negative external electrode 242 is electrically connected to the first negative internal electrode 113. The second negative external electrode 252 is made of a conductive material and is formed on the third end surface 110e, the fourth end surface 110f, and the eighth end surface 220f (see FIG. 55). As described above, the second negative internal electrode 223 is exposed at the eighth end surface 220f, and therefore the second negative external electrode 252 is electrically connected to the second negative internal electrode 223.

[0087] The first positive external electrode 241, the first negative external electrode 242, the second positive external electrode 251, and the second negative external electrode 252 are connected to a driving unit (not shown). The first positive external electrode 241 and the first negative external electrode 242 transmit a driving signal output from the driving unit to the first positive internal electrode 112 and the first negative internal electrode 113. The second positive external electrode 251 and the second negative external electrode 252 transmit a driving signal output from the driving unit to the second positive internal electrode 222 and the second negative internal electrode 223.

[0088] In this configuration, the first positive external electrode 241 and the first negative external electrode 242 function as external electrodes for the first piezoelectric actuator 110, and the second positive external electrode 251 and the second negative external electrode 252 function as external electrodes for the second piezoelectric actuator 220. This makes it possible to supply different drive signals to the first piezoelectric actuator 110 and the second piezoelectric actuator 220. Note that one of the positive and negative electrodes may be a common external electrode and the other an independent external electrode, and it is also possible to configure the first positive external electrode 241 and the second positive external electrode 251 to be electrically connected, or the first negative external electrode 242 and the second negative external electrode 252 to be electrically connected.

[0089] [Regarding the drive signals for the first and second piezoelectric actuators] The drive signals for the first piezoelectric actuator 110 and the second piezoelectric actuator 120 can be the same as those in the first embodiment. That is, the drive signal for the first piezoelectric actuator 110 can be an amplitude-modulated wave (see FIGS. 34 and 35) with a high frequency W1 as the carrier wave and a low frequency W2 as the modulating wave. The high frequency W1 is preferably 20 kHz or more and 100 kHz or less, and the low frequency W2 is preferably 1 Hz or more and 250 Hz or less. The drive signal for the second piezoelectric actuator 220 can be the same as that for the first piezoelectric actuator 110, or can be an amplitude-modulated wave with a first low frequency as the carrier wave and a second low frequency as the modulating wave. The first low frequency is preferably 110 Hz or more and 250 Hz or less, and the second low frequency is preferably 1 Hz or more and 50 Hz or less.

[0090] [About the mounting structure of the vibration generator] The mounting structure of the vibration generator 200 will be described. The vibration generator 200 can be bonded to a vibrating member. FIG. 60 is a perspective view of the vibration generator 200 bonded to a vibrating member 280, and FIG. 61 is a plan view of the vibration generator 200 bonded to the vibrating member 280. The vibrating member 280 is a member to which vibrations from the vibration generator 200 are transmitted, and may be, but is not limited to, a display panel, a track pad, or the housing of an electronic device. As shown in FIG. 61, the vibrating member 280 is bonded to the fourth main surface 220b of the second piezoelectric actuator 220. As shown in FIG. 60, two vibration generators 200 may be bonded to both ends of the vibrating member 280, or one or three or more vibration generators 200 may be bonded to the vibrating member 280. Alternatively, the vibration generator 200 may be disposed in the center of the mouse or the like so that the user can directly touch the fourth main surface 220b.

[0091] [Effects of vibration generator] The effects of the vibration generator 200 are similar to those of the vibration generator 100. That is, the first piezoelectric actuator 110 in the d31 mode can express vibrations in the force feedback region (low frequency region), and the second piezoelectric actuator 220 in the d33 mode can express high frequency levitation vibrations. Furthermore, by generating high frequency vibrations in the first piezoelectric actuator 110, the protruding shape of the second piezoelectric actuator 220 contributes, making it possible to express fine levitation vibrations.

[0092] Furthermore, in the vibration generator 200, the drive unit outputs a drive signal having an amplitude-modulated voltage waveform as shown in FIG. 36 to the first piezoelectric actuator 110, so that when the user places their finger in contact with the fourth main surface 220b or the vibrating member 280, a delicate tactile sensation can be realistically presented to the user's finger. Furthermore, the tactile sensation can be enhanced by moving the finger while keeping it in contact. Furthermore, because the high frequency wave W1 is amplitude-modulated, the average current of the entire waveform is smaller than when it is not amplitude-modulated, making it possible to reduce power consumption and heat generation. Furthermore, the amplitude-modulated wave can also suppress the generation of abnormal noise associated with the levitation phenomenon.

[0093] [Method of manufacturing the vibration generating device] The electromagnetic exciter 200 can be manufactured by the same method as the electromagnetic exciter 100 according to the first embodiment. That is, the first piezoelectric layer 111, the first positive internal electrode 112, and the first negative internal electrode 113 (see FIG. 5) are laminated, and then the second piezoelectric layer 221, the second positive internal electrode 222, and the second negative internal electrode 223 (see FIG. 43) are laminated thereon. This laminate is heated to sinter the first piezoelectric layer 111 and the second piezoelectric layer 221. Next, the second piezoelectric layer 221, the second positive internal electrode 222, and the second negative internal electrode 223 are cut to form a plurality of second piezoelectric actuators 220 (see FIG. 40). In this way, the electromagnetic exciter 200 is formed in which a plurality of second piezoelectric actuators 220 are laminated on one first piezoelectric actuator 110. In this way, the electromagnetic exciter 200 can be manufactured by a single sintering process. However, the electromagnetic exciter 200 can also be manufactured by other manufacturing methods. [Explanation of symbols]

[0094] 100...Vibration generator 110...First piezoelectric actuator 111...first piezoelectric layer 112...First positive internal electrode 113...First negative internal electrode 120...Second piezoelectric actuator 121...second piezoelectric layer 122...Second positive internal electrode 123…Second negative internal electrode 131...Positive external electrode 132...Negative external electrode 141...First positive external electrode 142...First negative external electrode 151...Second positive external electrode 152…Second negative external electrode 180...Vibration member 200...Vibration generator 220...Second piezoelectric actuator 221...Second piezoelectric layer 222...Second positive internal electrode 223…Second negative internal electrode 231...Positive external electrode 232...Negative external electrode 241...First positive external electrode 242...First negative external electrode 251...Second positive external electrode 252…Second negative external electrode 280...Vibration member

Claims

1. a first piezoelectric actuator comprising: a first piezoelectric layer made of a piezoelectric material; a first positive electrode internal electrode provided in the first piezoelectric layer; and a first negative electrode internal electrode provided in the first piezoelectric layer and facing the first positive electrode internal electrode in a second direction via the first piezoelectric layer, wherein when a voltage is applied between the first positive electrode internal electrode and the first negative electrode internal electrode, the first piezoelectric actuator expands and contracts along a first direction parallel to electrode surfaces of the first positive electrode internal electrode and the first negative electrode internal electrode; a second piezoelectric actuator that is laminated on the first piezoelectric actuator and includes a second piezoelectric layer made of a piezoelectric material, a second positive electrode internal electrode provided in the second piezoelectric layer, and a second negative electrode internal electrode that is provided in the second piezoelectric layer and faces the second positive electrode internal electrode in the second direction via the second piezoelectric layer, and that expands and contracts along the second direction perpendicular to the electrode surfaces of the second positive electrode internal electrode and the second negative electrode when a voltage is applied between the second positive electrode internal electrode and the second negative electrode internal electrode; A vibration generating device comprising:

2. The vibration generating device according to claim 1, the first piezoelectric actuator has a first end face which is an end face perpendicular to the first direction and parallel to the second direction, a second end face which is an end face perpendicular to the first direction and parallel to the second direction and opposite to the first end face, a third end face which is an end face parallel to the first direction and the second direction, and a fourth end face which is an end face parallel to the first direction and the second direction and opposite to the third end face, an end of the first positive internal electrode is exposed at the first end face, and an end of the first negative internal electrode is exposed at the second end face, The second piezoelectric actuator has a fifth end face which is an end face perpendicular to the first direction and parallel to the second direction, a sixth end face which is an end face perpendicular to the first direction and parallel to the second direction and opposite to the fifth end face, a seventh end face which is an end face parallel to the first direction and the second direction, and an eighth end face which is an end face parallel to the first direction and the second direction and opposite to the seventh end face, an end of the second positive internal electrode is exposed at the seventh end face, and an end of the second negative internal electrode is exposed at the eighth end face. Vibration generator.

3. The vibration generating device according to claim 2, a plurality of the second piezoelectric actuators arranged in a line along the first direction; the seventh end surface is a surface that is continuous with the third end surface, The eighth end surface is a surface that is continuous with the fourth end surface. Vibration generator.

4. The vibration generating device according to claim 3, positive electrode external electrodes provided on the first end surface, the third end surface, and the seventh end surface, and electrically connected to the first positive electrode internal electrode and the second positive electrode internal electrode; a negative electrode external electrode provided on the second end surface, the fourth end surface, and the eighth end surface, the negative electrode external electrode being electrically connected to the first negative electrode internal electrode and the second negative electrode internal electrode; The vibration generating device further comprises:

5. The vibration generating device according to claim 3, a first positive external electrode provided on the first end surface and electrically connected to the first positive internal electrode; a first negative electrode external electrode provided on the second end surface and electrically connected to the first negative electrode internal electrode; a second positive electrode external electrode provided on the seventh end surface and electrically connected to the second positive electrode internal electrode; a second negative electrode external electrode provided on the eighth end surface and electrically connected to the second negative electrode internal electrode; The vibration generating device further comprises:

6. The vibration generating device according to claim 2, a plurality of the second piezoelectric actuators arranged in two rows along the first direction; the seventh end surface faces the seventh end surface of the adjacent second piezoelectric actuator, The eighth end surface is a surface that is continuous with the third end surface and the fourth end surface. Vibration generator.

7. The vibration generator according to claim 6, a positive electrode external electrode provided on the first end surface and the seventh end surface and electrically connected to the first positive electrode internal electrode and the second positive electrode internal electrode; a negative electrode external electrode provided on the second end surface, the third end surface, the fourth end surface, and the eighth end surface, and electrically connected to the first negative electrode internal electrode and the second negative electrode internal electrode; The vibration generating device further comprises:

8. The vibration generator according to claim 6, a first positive external electrode provided on the first end surface and electrically connected to the first positive internal electrode; a first negative electrode external electrode provided on the second end surface and electrically connected to the first negative electrode internal electrode; a second positive electrode external electrode provided on the seventh end surface and electrically connected to the second positive electrode internal electrode; a second negative electrode external electrode provided on the eighth end surface and electrically connected to the second negative electrode internal electrode; The vibration generating device further comprises:

9. The vibration generator according to claim 4 or 7, The drive unit further includes a drive signal having a waveform obtained by amplitude-modulating a sine wave in a high frequency range having a frequency of 20 kHz to 100 kHz using a signal wave in a low frequency range having a frequency of 1 Hz to 250 Hz as a modulating wave, to the positive external electrode and the negative external electrode. Vibration generator.

10. The vibration generator according to claim 5 or 8, a driving unit configured to supply to the first positive external electrode and the first negative external electrode a driving signal having a waveform obtained by amplitude-modulating a sine wave in a high frequency range having a frequency of 20 kHz to 100 kHz with a modulating wave, the driving signal having a waveform obtained by modulating a signal wave in a low frequency range having a frequency of 1 Hz to 250 Hz as a modulating wave, the sine wave in a high frequency range having a frequency of 20 kHz to 100 kHz with the modulating wave. Vibration generator.

11. a first piezoelectric actuator comprising: a first piezoelectric layer made of a piezoelectric material; a first positive electrode internal electrode provided in the first piezoelectric layer; and a first negative electrode internal electrode provided in the first piezoelectric layer and facing the first positive electrode internal electrode in a second direction via the first piezoelectric layer, wherein when a voltage is applied between the first positive electrode internal electrode and the first negative electrode internal electrode, the first piezoelectric actuator expands and contracts along a first direction parallel to electrode surfaces of the first positive electrode internal electrode and the first negative electrode internal electrode; a second piezoelectric actuator that is laminated on the first piezoelectric actuator and includes a second piezoelectric layer made of a piezoelectric material, a second positive electrode internal electrode provided in the second piezoelectric layer, and a second negative electrode internal electrode that is provided in the second piezoelectric layer and faces the second positive electrode internal electrode in the second direction via the second piezoelectric layer, and that expands and contracts along the second direction perpendicular to electrode surfaces of the second positive electrode internal electrode and the second negative electrode internal electrode when a voltage is applied between the second positive electrode internal electrode and the second negative electrode; An electronic device comprising:

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