Braille tactile sense generating device, Braille tactile sense generating system, and Braille tactile sense generating device driving method

Abstract

To provide a braille tactile perception generating device that can be reduced in a size and in weight and is excellent in a response speed, a braille tactile perception generating system, and a driving method for a braille tactile perception generating device.SOLUTION: A braille tactile perception generating device 100 is equipped with a plurality of piezoelectric actuators 101, a seating 102 and a vibration transmission plate 103. When a voltage is applies to a space between a positive internal electrode and a negative internal electrode, each of the piezoelectric actuators extends and contracts along a direction perpendicular to electrode planes of the positive internal electrode and of the negative internal electrode, which has first surfaces which are parallel to the electrode planes and second surfaces which are parallel to the electrode planes and are at an opposite side of the first surface. The seating has a first joint surface including a plurality of first joint regions which is regions joined with the first surface, and first concave parts recessed from the first joint surface, provided around the first joint regions respectively, in which there is formed a plurality of first vibration parts, surrounded respectively by the first concave parts, which have one first joint region. The vibration transmission plate is joined with the plurality of second surfaces.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a Braille tactile sense generating device, a Braille tactile sense generating system, and a Braille tactile sense generating device driving method, which are related to Braille tactile sense presentation by vibration. [Background technology]

[0002] Various actuators are used in haptic functional 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. Haptic technology is becoming more sophisticated, and technology has been developed that can reproduce tactile sensations such as roughness and smoothness in addition to notification functions (see, for example, Patent Document 1). Furthermore, there is a demand for different tactile surfaces in different areas on LCD panels of mobile devices, etc.

[0003] In recent years, there has also been research into the use of tactile functional devices to reproduce the tactile sensation of Braille, and a Braille display device has been developed that uses a piezoelectric actuator to mechanically raise and lower protrusions arranged in the shape of Braille, thereby presenting the tactile sensation of Braille to the user. [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] However, a structure that mechanically moves the protrusions up and down has the problem of being large in size and having a slow response speed. Therefore, the inventors investigated the generation of Braille tactile sensations using tactile technology that uses vibrations from a piezoelectric actuator.

[0006] In view of the above circumstances, an object of the present invention is to provide a Braille tactile sense generating device, a Braille tactile sense generating system, and a Braille tactile sense generating device driving method that can be made small and lightweight and have an excellent response speed. [Means for solving the problem]

[0007] In order to achieve the above object, a Braille tactile sense generating device according to one embodiment of the present invention includes a plurality of piezoelectric actuators, a base, and a vibration transmission plate. Each of the plurality of piezoelectric actuators includes a piezoelectric layer made of a piezoelectric material, a positive internal electrode provided in the piezoelectric layer, and a negative internal electrode provided in the piezoelectric layer and facing the positive internal electrode via the piezoelectric layer, and when a voltage is applied between the positive internal electrode and the negative internal electrode, the piezoelectric actuator expands and contracts along a direction perpendicular to the electrode surfaces of the positive internal electrode and the negative internal electrode, and has a first surface parallel to the electrode surfaces and a second surface parallel to the electrode surfaces and opposite to the first surface. The base has a first bonding surface including a plurality of first bonding areas, which are areas where one of the first surfaces is bonded, and a first recess provided around each of the first bonding areas and recessed from the first bonding surface, and multiple first vibration parts are formed, each surrounded by the first recess and having one of the first bonding areas. The vibration transmitting plate has a plurality of second surfaces joined together.

[0008] The vibration transmission plate may have a second bonding surface including a plurality of second bonding areas, which are areas where one of the second surfaces is bonded, and second recesses provided around each of the second bonding areas and recessed from the second bonding surface, and may have a plurality of second vibration sections each surrounded by the second recess and having one of the second bonding areas.

[0009] The Braille tactile sensation generating device is a first vibration suppressing member filled in the first recess and configured to suppress vibration transmission between the plurality of first vibrating portions; a second vibration suppressing member filled in the second recess and configured to reduce vibration transmission between the plurality of second vibrating portions; may further comprise:

[0010] the plurality of piezoelectric actuators is six piezoelectric actuators; The six piezoelectric actuators may be arranged in three rows and two columns when viewed in a direction perpendicular to the electrode surface.

[0011] Each of the plurality of piezoelectric actuators may be made up of a plurality of piezoelectric actuator chips, and the plurality of actuator chips may be stacked with a direction perpendicular to the electrode surface as the stacking direction.

[0012] Each of the piezoelectric actuator chips includes a plurality of blocks each including a predetermined number of the positive internal electrodes and the negative internal electrodes, and a buffer layer is provided between the plurality of blocks; The relaxation layer may be the piezoelectric layer having a thickness greater than the thickness of the piezoelectric layer between the positive internal electrode and the negative internal electrode in the block.

[0013] The Braille tactile sense generating device may further include a driving unit that supplies a driving signal having a waveform obtained by amplitude-modulating a sine wave having a frequency of 150 Hz or more and 300 Hz or less with a signal wave having a frequency of 2 Hz or more and 50 Hz or less as a modulating wave to the positive internal electrode and the negative internal electrode.

[0014] In order to achieve the above object, a Braille tactile sense generation system according to one embodiment of the present invention includes a Braille tactile sense generation device and a drive unit. The Braille tactile sense generating device includes a plurality of piezoelectric actuators, each of which includes a piezoelectric layer made of a piezoelectric material, a positive internal electrode provided in the piezoelectric layer, and a negative internal electrode provided in the piezoelectric layer and facing the positive internal electrode via the piezoelectric layer. When a voltage is applied between the positive internal electrode and the negative internal electrode, the piezoelectric actuators expand and contract along a direction perpendicular to the electrode surfaces of the positive internal electrode and the negative internal electrode, and have a first surface parallel to the electrode surface and a second surface parallel to the electrode surface and opposite to the first surface; a first bonding surface including a plurality of first bonding areas where one of the first surfaces is bonded, and first recesses provided around each of the first bonding areas and recessed from the first bonding surface, a base on which a plurality of first vibration sections are formed, each surrounded by the first recess and having one of the first bonding areas; and a vibration transmission plate to which a plurality of the second surfaces are bonded. The drive unit uses a signal wave with a frequency of 2 Hz or more and 50 Hz or less as a modulating wave, and supplies a drive signal having a waveform obtained by amplitude-modulating a sine wave with a frequency of 150 Hz or more and 300 Hz or less by the modulating wave to the positive internal electrode and the negative internal electrode.

[0015] In order to achieve the above object, a driving method for a Braille tactile sense generating device according to one aspect of the present invention is a method for driving a plurality of piezoelectric actuators, each of which comprises a piezoelectric layer made of a piezoelectric material, a positive internal electrode provided in the piezoelectric layer, and a negative internal electrode provided in the piezoelectric layer and facing the positive internal electrode via the piezoelectric layer, and when a voltage is applied between the positive internal electrode and the negative internal electrode, the piezoelectric actuator expands and contracts along a direction perpendicular to the electrode surfaces of the positive internal electrode and the negative internal electrode, and has a first surface parallel to the electrode surfaces and a second surface parallel to the electrode surfaces. a first bonding surface including a plurality of first bonding areas, each of which is an area where one of the first surfaces is bonded, and a first recess provided around each of the first bonding areas and recessed from the first bonding surface, the base having a plurality of first vibration sections each surrounded by the first recess and having one of the first bonding areas; and a vibration transmission plate to which the plurality of second surfaces are bonded, the device supplies drive signals individually to the plurality of piezoelectric actuators. [Effects of the Invention]

[0016] As described above, according to the present invention, it is possible to provide a Braille tactile sense generation device, a Braille tactile sense generation system, and a Braille tactile sense generation device driving method that can be made small and lightweight and have excellent response speed. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a perspective view of a Braille tactile sense generation device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a perspective view of the Braille tactile sense generating device. [Figure 3] FIG. 2 is an exploded perspective view of the Braille tactile sense generating device. [Figure 4] FIG. 2 is an exploded perspective view of the Braille tactile sense generating device. [Figure 5] FIG. 2 is a side view of the Braille tactile sense generating device. [Figure 6] FIG. 2 is a plan view of a piezoelectric actuator included in the Braille tactile sense generating device. [Figure 7] FIG. 2 is a side view of the piezoelectric actuator. [Figure 8] FIG. 2 is a perspective view of a base provided in the Braille tactile sense generating device. [Figure 9] FIG. [Figure 10] FIG. [Figure 11] FIG. [Figure 12] FIG. 2 is a cross-sectional view of the base and the piezoelectric actuator. [Figure 13] FIG. 2 is a plan view of the base and the piezoelectric actuator. [Figure 14] FIG. 4 is a perspective view of a first vibrating part of the base. [Figure 15] FIG. 2 is a perspective view of a vibration transmission plate provided in the Braille tactile sense generating device. [Figure 16] FIG. 2 is a plan view of the vibration transmission plate. [Figure 17] FIG. 3 is a cross-sectional view of the vibration transmission plate. [Figure 18] FIG. 3 is a cross-sectional view of the vibration transmission plate. [Figure 19] FIG. 2 is a cross-sectional view of the vibration transmission plate and the piezoelectric actuator. [Figure 20] FIG. 2 is a plan view of the vibration transmission plate and the piezoelectric actuator. [Figure 21] FIG. 4 is a perspective view of a second vibrating portion of the vibration transmission plate. [Figure 22] 3 is a perspective view of a first vibration suppressing member and the base provided in the Braille tactile sense generating device. FIG. [Figure 23] FIG. 4 is a cross-sectional view of the first vibration suppressing member and the base. [Figure 24] 3 is a perspective view of a second vibration suppressing member and the vibration transmitting plate provided in the Braille tactile sense generating device. FIG. [Figure 25] 4 is a cross-sectional view of the second vibration suppressing member and the vibration transmitting body. FIG. [Figure 26] FIG. 2 is a plan view of a piezoelectric actuator included in the Braille tactile sense generating device. [Figure 27]FIG. 2 is a cross-sectional view of a piezoelectric actuator chip that constitutes the piezoelectric actuator. [Figure 28] 3 is a schematic diagram showing the thickness of a piezoelectric layer in the piezoelectric actuator chip. FIG. [Figure 29] 3A to 3C are schematic diagrams illustrating vibrations of the piezoelectric actuator chip. [Figure 30] 3A and 3B are schematic diagrams showing the orientation of the piezoelectric actuator chip. [Figure 31] 3A to 3C are schematic diagrams illustrating the operation of the Braille tactile sense generating device. [Figure 32] 3A to 3C are schematic diagrams illustrating the operation of the Braille tactile sense generating device. [Figure 33] 3A to 3C are schematic diagrams illustrating the operation of the Braille tactile sense generating device. [Figure 34] 10 shows an amplitude-modulated waveform generated by a driving unit included in the tactile presentation device. [Figure 35] This is an enlarged waveform of the amplitude modulated wave in FIG. [Figure 36] 1 shows an amplitude-modulated waveform (voltage waveform only) generated by a driving unit included in the tactile presentation device. [Figure 37] This is an enlarged waveform of the amplitude modulated wave in FIG. [Figure 38] FIG. 2 is a schematic diagram showing the amplitude of an amplitude-modulated wave. [Figure 39] 10 is an example of an amplitude modulated waveform generated by the driving unit. [Figure 40] 10 is an example of an amplitude modulated waveform generated by the driving unit. DETAILED DESCRIPTION OF THE INVENTION

[0018] A braille tactile sense generating device according to an embodiment of the present invention will be described.

[0019] [Configuration of the Braille tactile generation device] FIG. 1 is a perspective view of a Braille tactile sense generation device 100 according to this embodiment, and FIG. 2 is a see-through view of a portion of the Braille tactile sense generation device 100. FIGS. 3 and 4 are exploded perspective views of the Braille tactile sense generation device 100, viewed from opposite directions. FIG. 5 is a side view of the Braille tactile sense generation device 100. As shown in these figures, the Braille tactile sense generation device 100 comprises a piezoelectric actuator 101, a base 102, a vibration transmission plate 103, a first vibration suppression member 104, and a second vibration suppression member 105. As shown in FIGS. 3 and 4, the Braille tactile sense generation device 100 comprises a plurality of piezoelectric actuators 101.

[0020] The piezoelectric actuators 101 generate vibrations and generate Braille tactile sensations. FIG. 6 is a plan view showing the arrangement of the piezoelectric actuators 101 on the base 102. As shown in the figure, the Braille tactile sensation generating device 100 has six piezoelectric actuators 101, which are spaced apart and arranged in three rows and two columns. This arrangement complies with the standard for six-dot Braille. FIG. 7 is a side view of one piezoelectric actuator 101. As shown in the figure, the piezoelectric actuator 101 has a first surface 110a and a second surface 110b. The first surface 110a and the second surface 110b are surfaces on opposite sides of the piezoelectric actuator 101. The detailed configuration of the piezoelectric actuator 101 will be described later.

[0021] The base 102 supports the piezoelectric actuator 101. Fig. 8 is a perspective view of the base 102, and Fig. 9 is a plan view of the base 102. Figs. 8 and 9 show the surface of the base 102 facing the piezoelectric actuator 101. Figs. 10 and 11 are cross-sectional views of the base 102, with Fig. 10 being a cross-sectional view taken along line AA in Fig. 9 and Fig. 11 being a cross-sectional view taken along line BB in Fig. 9.

[0022] As shown in these figures, the base 102 has a first bonding surface 102a. The first bonding surface 102a is the surface of the base 102 facing the piezoelectric actuator 101. As shown in FIG. 9, the first bonding surface 102a includes a plurality of first bonding regions 121. FIG. 12 is a cross-sectional view showing the base 102 and the piezoelectric actuator 101, and FIG. 13 is a plan view showing the base 102 and the piezoelectric actuator 101. As shown in these figures, the first bonding region 121 is the region where the first surface 110a of the piezoelectric actuator 101 is bonded. The first surface 110a and the first bonding region 121 can be bonded with an adhesive. Because the Braille tactile sense generation device 100 includes six piezoelectric actuators 101, the first bonding surface 102a includes six first bonding regions 121, and the six first bonding regions 121 are spaced apart from one another.

[0023] The base 102 further has first recesses 122. As shown in FIGS. 8 to 11, the first recesses 122 are provided around the periphery of each first bonding region 121 and are recesses recessed from the first bonding surface 102a. The depth of the first recesses 122 is preferably 3 mm or more. As shown in FIGS. 8, 10, and 11, the first recesses 122 form first vibrating portions 123 in the base 102.

[0024] Fig. 14 is a perspective view showing only the first vibrating parts 123. The first vibrating parts 123 are columnar parts of the base 102 surrounded by the first recesses 122, and as shown in Fig. 14, each has one first bonding area 121, with the same number of first bonding areas 121 being formed. The first vibrating parts 123 are separated from adjacent first vibrating parts 123 by the first recesses 122, so that vibrations are not transmitted to adjacent first vibrating parts 123. The material of the base 102 is not particularly limited, but a highly rigid material such as stainless steel is preferable.

[0025] Vibration transmission plate 103 transmits vibrations generated by piezoelectric actuator 101. Fig. 15 is a perspective view of vibration transmission plate 103, and Fig. 16 is a plan view of vibration transmission plate 103. Figs. 15 and 16 show the surface of vibration transmission plate 103 facing the piezoelectric actuator 101. Figs. 17 and 18 are cross-sectional views of vibration transmission plate 103, with Fig. 17 being a cross-sectional view taken along line CC in Fig. 16 and Fig. 18 being a cross-sectional view taken along line DD in Fig. 16.

[0026] As shown in these figures, the vibration propagation plate 103 is flat and has a second bonding surface 103a and a tactile sensation providing surface 103b. The second bonding surface 103a is the surface of the vibration propagation plate 103 facing the piezoelectric actuator 101, and the tactile sensation providing surface 103b is the surface of the vibration propagation plate 103 opposite the second bonding surface 103a. As shown in FIG. 16, the second bonding surface 103a includes a plurality of second bonding regions 131. FIG. 19 is a cross-sectional view showing the vibration propagation plate 103 and the piezoelectric actuator 101, and FIG. 20 is a plan view showing the vibration propagation plate 103 and the piezoelectric actuator 101. As shown in these figures, the second bonding region 131 is the region to which the second surface 110b of the piezoelectric actuator 101 is bonded. The second surface 110b and the second bonding region 131 can be bonded using an adhesive. Since the Braille tactile-sense generating device 100 includes six piezoelectric actuators 101, the second bonding surface 103a includes six second bonding areas 131, and the six second bonding areas 131 are spaced apart from one another.

[0027] The vibration transmission plate 103 further has second recesses 132. As shown in FIGS. 15 to 18, the second recesses 132 are provided around the periphery of each second bonding region 131 and are recesses recessed from the second bonding surface 103a. There are no particular limitations on the depth of the second recesses 132, but a depth of 3 mm or more is preferable. As shown in FIGS. 15, 17, and 18, the second recesses 132 form second vibration portions 133 in the vibration transmission plate 103.

[0028] 21 is a perspective view showing only the second vibrating portions 133. The second vibrating portions 133 are columnar portions of the vibration transmitting plate 103 that are surrounded by second recesses 132, and as shown in FIG. 21, each has one second bonding area 131, with the same number of second bonding areas 131 formed. The second vibrating portions 133 are separated from adjacent second vibrating portions 133 by the second recesses 132, and are configured so that vibrations are not transmitted to the adjacent second vibrating portions 133.

[0029] The tactile sense providing surface 103b is a surface to which vibrations are transmitted by the second vibrating unit 133, and which provides the tactile sensation of Braille to a user who touches the tactile sense providing surface 103b. As shown in Fig. 1, the tactile sense providing surface 103b is a flat surface, and can be a surface parallel to the second bonding surface 103a. The material of the vibration transmitting plate 103 is not particularly limited, but a highly rigid material such as polycarbonate, polyester carbonate, or glass is preferable.

[0030] The first vibration damping member 104 damps vibration transmission between the first vibrating units 123. FIG. 22 is a perspective view of the base 102 and the first vibration damping member 104. FIG. 23 is a cross-sectional view of the base 102 and the first vibration damping member 104, taken along the line E-E in FIG. 22. As shown in these figures, the first vibration damping member 104 fills the first recess 122, and the first vibrating units 123 are embedded in the first vibration damping member 104 except for the first bonding region 121. The first vibration damping member 104 is made of a material capable of damping vibration, such as silicone, vibration-absorbing gel, or rubber. As a result, vibrations from each first vibrating unit 123 are absorbed by the first vibration damping member 104 and are not transmitted to other first vibrating units 123. Note that the Braille tactile sense generating device 100 may not include the first vibration damping member 104, and the first recess 122 may be empty.

[0031] The second vibration damping member 105 damps vibration transmission between the second vibrating units 133. FIG. 24 is a perspective view of the vibration transmission plate 103 and the second vibration damping member 105. FIG. 25 is a cross-sectional view of the vibration transmission plate 103 and the second vibration damping member 105, taken along line FF in FIG. 24. As shown in these figures, the second vibration damping member 105 fills the second recess 122, and the second vibrating units 133 are embedded in the second vibration damping member 105 except for the second bonding region 131. The second vibration damping member 105 is made of a material capable of damping vibration, such as silicone, vibration-absorbing gel, or rubber. As a result, vibrations from each second vibrating unit 133 are absorbed by the second vibration damping member 105 and are not transmitted to other second vibrating units 133. Note that the Braille tactile sense generating device 100 may not include the second vibration damping member 105, and the second recess 132 may be empty.

[0032] The Braille tactile sense generation device 100 has the above-described configuration. As shown in Fig. 5, the Braille tactile sense generation device 100 is configured by joining six piezoelectric actuators 101 onto a base 102, and joining a vibration transmission plate 103 onto the six piezoelectric actuators 101. The vibration transmission plate 103 abuts only the six piezoelectric actuators 101 and is spaced apart from the base 102. The size of the Braille tactile sense generation device 100 is not particularly limited, but can be such that the tactile sense presentation surface 103b is approximately the same size as a fingertip.

[0033] [Specific configuration of piezoelectric actuator] The specific configuration of the piezoelectric actuator 101 will be described. FIG. 26 is a plan view showing the piezoelectric actuator 101. As shown in the figure, each piezoelectric actuator 101 is configured by stacking two piezoelectric actuator chips: a first piezoelectric actuator chip 111 and a second piezoelectric actuator chip 112. The first piezoelectric actuator chip 111 and the second piezoelectric actuator chip 112 can be piezoelectric actuator chips having the same structure. FIG. 27 is a schematic diagram of a piezoelectric actuator chip 140 that can form the first piezoelectric actuator chip 111 and the second piezoelectric actuator chip 112.

[0034] As shown in the figure, the piezoelectric actuator chip 140 includes a piezoelectric layer 141, a positive internal electrode 142, and a negative internal electrode 143. One main surface of the piezoelectric actuator chip 140 is designated as main surface 140a, the main surface opposite main surface 140a is designated as main surface 140b, one side surface is designated as side surface 140c, and the side surface opposite side surface 140c is designated as side surface 140d. The piezoelectric layer 141 is made of a piezoelectric material such as PZT (lead zirconate titanate).

[0035] The positive internal electrode 142 is made of a conductive material and is provided in the piezoelectric layer 141. The positive internal electrode 142 faces the negative internal electrode 143 via the piezoelectric layer 141. The positive internal electrode 142 is flat, and when the main surface of the positive internal electrode 142 is taken as the electrode surface, the electrode surface is parallel to the main surfaces 140a and 140b. As shown in FIG. 27 , the positive internal electrode 142 is exposed on the side surface 140c and is spaced from the side surface 140d. The positive internal electrode 142 abuts on and is electrically connected to a positive external electrode (not shown) formed on the side surface 140c.

[0036] The negative electrode internal electrode 143 is made of a conductive material and is provided in the piezoelectric layer 141. The negative electrode internal electrode 143 faces the positive electrode internal electrode 142 via the piezoelectric layer 141. The negative electrode internal electrode 143 is flat, and when the main surface of the positive electrode internal electrode 142 is taken as the electrode surface, the electrode surface is parallel to the main surfaces 140a and 140b. As shown in FIG. 27 , the negative electrode internal electrode 143 is exposed on the side surface 140d and is spaced from the side surface 140c. The negative electrode internal electrode 143 abuts on and is electrically connected to a negative electrode external electrode (not shown) formed on the side surface 140d.

[0037] As shown in FIG. 27 , the piezoelectric actuator chip 140 has a block 151 and a relaxation layer 152. The block 151 includes a plurality of positive internal electrodes 142 and a plurality of negative internal electrodes 143, and three blocks 151 are provided in the piezoelectric actuator chip 140. The number of positive internal electrodes 142 and negative internal electrodes 143 included in each block 151 is not particularly limited, but may be 50 layers in total. Therefore, the piezoelectric actuator chip 140 may be provided with a total of 150 layers of positive internal electrodes 142 and negative internal electrodes 143 across the three blocks 151. For convenience, FIG. 27 illustrates each block 151 as including three layers of positive internal electrodes 142 and negative internal electrodes 143.

[0038] The relaxation layer 152 is provided between the blocks 151 and on the main surface 140a and main surface 140b sides of the piezoelectric actuator chip 140. The relaxation layer 152 is made of a thick piezoelectric layer 141. FIG. 28 is a schematic diagram showing the thickness of the relaxation layer 152. As shown in the figure, the thickness of the piezoelectric layer 141 between the positive electrode internal electrode 142 and the negative electrode internal electrode 143 in each block 151 is thickness T1, and the thickness of the piezoelectric layer 141 in the relaxation layer 152 is thickness T2. Thickness T2 is thicker than thickness T1 and is preferably at least twice as thick as thickness T1; for example, thickness T1 can be 18 μm and thickness T2 can be 36 μm.

[0039] The piezoelectric actuator chip 140 can be formed by forming a positive internal electrode 142 or a negative internal electrode 143 using a conductive paste on a piezoelectric plate that will become the piezoelectric layer 141, and then stacking and sintering the piezoelectric plates. Here, if a large number of piezoelectric plates are stacked, the piezoelectric actuator chip 140 can be formed by forming a sintered body for each block 151, and then stacking and compressing the blocks 151. In this case, the buffer layer 152 strengthens the adhesion between the blocks 151 and also relieves internal stress during compression, making it possible to form a piezoelectric actuator chip 140 with excellent characteristics. The number of blocks 151 is not limited to three, and may be two or less, or four or more.

[0040] The piezoelectric actuator chip 140 has such a configuration. FIG. 29 is a schematic diagram showing the vibration of the piezoelectric actuator chip 140. When a voltage having a predetermined waveform is applied between the positive internal electrode 142 and the negative internal electrode 143, the piezoelectric actuator chip 140 expands and contracts (indicated by the arrow in the figure) in a direction (Z direction) perpendicular to the electrode surfaces (XY plane) of the positive internal electrode 142 and the negative internal electrode 143 due to the inverse piezoelectric effect in the piezoelectric layer 141, and vibrates with the same direction (Z direction) as the amplitude direction. This type of vibration is called the d33 mode. Hereinafter, the voltage waveform applied between the positive internal electrode 142 and the negative internal electrode 143 will be referred to as the drive signal for the piezoelectric actuator chip 140. The piezoelectric actuator chip 140 operating in the d33 mode can also be driven unipolarly by adding a DC component, which can also prevent polarization degradation.

[0041] As described above, the piezoelectric actuator 101 includes the first piezoelectric actuator chip 111 and the second piezoelectric actuator chip 112, and the first piezoelectric actuator chip 111 and the second piezoelectric actuator chip 112 each have the configuration of the piezoelectric actuator chip 140. Figure 30 is a schematic diagram showing the orientation of the piezoelectric actuator chip 140 that constitutes the piezoelectric actuator 101.

[0042] As shown in the figure, the two piezoelectric actuator chips 140 are stacked with the stacking direction being a direction (Z direction) perpendicular to the electrode surfaces (XY plane) of the positive internal electrode 142 and the negative internal electrode 143. The two piezoelectric actuator chips 140 are bonded to the base 102 and the vibration transmitting plate 103 in an orientation such that the electrode surfaces (XY plane) of the positive internal electrode 142 and the negative internal electrode 143 are parallel to the first bonding surface 102a and the second bonding surface 103a.

[0043] Therefore, piezoelectric actuator 101 is a piezoelectric actuator (hereinafter referred to as d33 piezoelectric actuator) that vibrates in the d33 mode with its vibration direction being perpendicular to first bonding surface 102a and second bonding surface 103a (Z direction). Note that second main surface 140b of first piezoelectric actuator chip 111 corresponds to first surface 110a of piezoelectric actuator 101, and first main surface 140a of second piezoelectric actuator chip 112 corresponds to second surface 110b of piezoelectric actuator 101. Since the displacement amount of the d33 piezoelectric actuator is expressed by the following (Equation 1), it is possible to configure piezoelectric actuator 101 by stacking two piezoelectric actuator chips 140 to form a multi-stage structure and increase the displacement amount.

[0044] Δz=d33·v·n (Equation 1) Here, Δz represents the displacement, d33 represents the material constant of the piezoelectric layer 141, v represents the applied voltage, and n represents the number of laminated piezoelectric layers.

[0045] The piezoelectric actuator 101 has the above-described configuration. While the piezoelectric actuator 101 is configured with two piezoelectric actuator chips 140, it may be configured with one or three or more piezoelectric actuator chips 140. Furthermore, the piezoelectric actuator 101 may have other configurations as long as it is a d33 piezoelectric actuator whose vibration direction is a direction perpendicular to the first bonding surface 102a and the second bonding surface 103a (Z direction).

[0046] [Operation and effects of the Braille tactile generation device] FIG. 31 is a schematic diagram showing the operation of the Braille tactile sense generation device 100. As described above, in the Braille tactile sense generation device 100, by driving the piezoelectric actuators 101, the piezoelectric actuators 101 can be expanded and contracted in a direction (Z direction) perpendicular to the tactile sense generation surface 103b (XY plane) and vibrated in the d33 mode with the same direction (Z direction) as the amplitude direction. In FIG. 31, the vibration direction of the piezoelectric actuators 101 is indicated by an arrow. The vibration of each piezoelectric actuator 101 is transmitted to the tactile sense generation surface 103b via the second vibrating unit 133, forming a vibration point directly above each piezoelectric actuator 101. In FIG. 31, the vibration point formed by each piezoelectric actuator 101 on the tactile sense generation surface 103b is indicated as vibration point P. When a user touches the tactile sense generation surface 103b with a finger or the like, the user can sense the vibration of each vibration point P.

[0047] The Braille tactile sense generating device 100 is equipped with six piezoelectric actuators 101, and each piezoelectric actuator 101 can be driven individually. Fig. 32 is a schematic diagram of the tactile sense presentation surface 103b. In the figure, the six piezoelectric actuators 101 are shown as piezoelectric actuators 101a to 101f, respectively, and the vibration points P at which vibration is generated by each piezoelectric actuator 101 are respectively shown as vibration points P a ~P f When the piezoelectric actuator 101a is driven, the vibration point P a vibrates, and when the piezoelectric actuator 101b is driven, the vibration point P b Similarly, the piezoelectric actuators 101c to 101f are driven to vibrate the vibration point P c ~P f vibrates.

[0048] As a result, the Braille tactile sense generating device 100 can generate a Braille tactile sense based on six-dot Braille to the user who is touching the tactile sense presentation surface 103b. FIG. 33 is a schematic diagram showing a user's finger F touching the tactile sense presentation surface 103b. As shown in the figure, the user can touch the tactile sense presentation surface 103b with the fingertip of the finger F. In this state, when the Braille tactile sense generating device 100 drives each piezoelectric actuator 101, the user can read Braille based on the six-dot Braille standard. For example, when the vibration point P a vibrates and other vibration points P do not vibrate, the user can read the Braille letter "A." a , P c and P d vibrates and other vibration points P do not vibrate, the user can read the Braille "M." a , P c , P d and P f vibrates and other vibration points P do not vibrate, the user can read the Braille character "X." In this way, the Braille tactile sense generation device 100 can generate a Braille tactile sense depending on whether or not the vibration point P vibrates.

[0049] Here, in order for the user to read the Braille, it is necessary to locally vibrate the vibration point P. If a wide range of the tactile sense presentation surface 103b is vibrated when any one of the piezoelectric actuators 101 is driven, the user will not be able to distinguish which vibration point P is vibrating. Furthermore, if two or more piezoelectric actuators 101 are driven simultaneously, the user will not be able to distinguish which vibration point P is vibrating.

[0050] In contrast, in the Braille tactile sense generation device 100, a plurality of first vibrating units 123 (see FIG. 14) are provided on the base 102, and the first vibrating units 123 are spaced apart from one another by first recesses 122 and first vibration suppressing members 104. This prevents vibrations generated by the piezoelectric actuators 101 from being transmitted between the first vibrating units 123. In addition, in the Braille tactile sense generation device 100, a plurality of second vibrating units 133 (see FIG. 21) are provided on the vibration transmitting plate 103, and the second vibrating units 133 are spaced apart from one another by second recesses 132 and second vibration suppressing members 105. This prevents vibrations generated by the piezoelectric actuators 101 from being transmitted between the second vibrating units 133. As a result, in the Braille tactile sense generation device 100, when each piezoelectric actuator 101 is driven, a vibration point P directly above it locally vibrates, allowing the user to read Braille accurately.

[0051] The Braille tactile sense generation device 100 can generate Braille tactile sense using a flat tactile sense presentation surface 103b, and does not require deformation of the tactile sense presentation surface 103b, making it highly versatile and durable. Furthermore, in the Braille tactile sense generation device 100, the vibration direction (Z direction) of the piezoelectric actuator 101 coincides with the pressing direction (Z direction) of the finger F touching the tactile sense presentation surface 103b, making it possible to advantageously utilize the force generated by the piezoelectric actuator 101 in this direction (Z direction). Furthermore, the d33 piezoelectric actuator has the greatest durability in the vibration direction, which can improve the durability of the piezoelectric actuator 101.

[0052] Furthermore, the piezoelectric actuator 101 does not have a mechanical driving part such as a motor, and is composed of a small, lightweight, and low-power-consuming piezoelectric actuator chip 140, which allows for space-saving and low-power consumption of the Braille tactile sense generation device 100. In addition, because the piezoelectric actuator 101 has high speed response, the Braille tactile sense generation device 100 can present Braille tactile sensations by taking advantage of this high speed response. This is also effective for presenting Braille characters that are automatically generated in accordance with content such as video and audio. Note that in languages ​​such as Japanese, two six-dot Braille characters are required to represent voiced consonants, etc. In this case, two Braille tactile sense generation devices 100 can be arranged side by side.

[0053] [About the drive signal] The drive signal output to the piezoelectric actuator 101 will now be described. As described above, this drive signal is a voltage waveform applied between the positive internal electrode 142 and the negative internal electrode 143 of the piezoelectric actuator chip 140. Note that this drive signal may be supplied to the piezoelectric actuator 101 from a drive unit mounted on the Braille tactile sense generation device 100, or may be supplied to the piezoelectric actuator 101 from a drive unit mounted on a device separate from the Braille tactile sense generation device 100 via wireless communication or the like.

[0054] (Drive signal 1) The drive signal output from the drive unit to the piezoelectric actuator 101 has a waveform obtained by amplitude-modulating a sine wave with a frequency of 150 Hz to 300 Hz using a signal wave with a frequency of 2 Hz to 50 Hz as a modulating wave. Here, vibrations of 150 Hz to 300 Hz can be sensed by Pacinian corpuscles, which are receptors in the human skin.

[0055] Fig. 34 shows voltage and current waveforms having an amplitude-modulated wave waveform obtained by using a sine wave having a first frequency as a modulating wave and amplitude-modulating a sine wave having a second frequency with this modulating wave. Fig. 35 is an enlarged view of Fig. 34. When the voltage waveform shown in Fig. 34 is applied as a drive signal from the drive unit to piezoelectric actuator 101, a current having the current waveform shown in the figure flows.

[0056] Figure 36 shows only the voltage waveform of Figure 34, and Figure 37 shows only the voltage waveform of Figure 35. In Figures 36 and 37, the wave with a long wavelength designated W1 is a sine wave having a first frequency, and the wave with a short wavelength designated W2 is a sine wave having a second frequency. Hereinafter, the sine wave having the first frequency will be referred to as the first sine wave W1, and the sine wave having the second frequency will be referred to as the second sine wave W2.

[0057] 36 and 37, the first sine wave W1 is formed by changing the amplitude of the second sine wave W2, i.e., the waveforms shown in Figures 36 and 37 are amplitude-modulated waves with the second sine wave W2 as the carrier wave and the first sine wave W1 as the modulating wave. The driving unit can generate a drive signal having an amplitude-modulated waveform with the second sine wave W2 of 150 Hz or more and 300 Hz or less as the carrier wave and the first sine wave W1 of 2 Hz or more and 50 Hz or less as the modulating wave, and apply it to the piezoelectric actuator 101.

[0058] 38 is a schematic diagram showing the relationship between the waveform of an amplitude-modulated wave and 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 modulation depth m is expressed by the following (Equation 2). As shown in the following (Equation 2), the smaller the amplitude b is relative to amplitude a, the greater the modulation depth m.

[0059] m=(ab) / (a+b) (Equation 2)

[0060] In Figure 36, as shown by the white arrow in Figure 36, increasing the voltage gain of the first sine wave W1 deepens the "valley bottom" of the first sine wave W1. When the voltage gain of the first sine wave W2 is set to 0 dB, the amplitude of the "valley bottom" is minimized. Furthermore, decreasing the voltage gain of the first sine wave W1 shallows the "valley bottom" of the first sine wave W1 and increases its amplitude. Furthermore, decreasing the voltage gain of the first sine wave W1 makes the amplitude b of the "valley bottom" of the first sine wave W1 equal to the amplitude of the "peak," eliminating the "valley." In this embodiment, the modulation depth m is adjusted within a range of 50% to 100%, allowing the amplitude modulation difference to be utilized for haptic expression. Furthermore, since current consumption is reduced in areas where the voltage is reduced, it is also possible to achieve low power consumption. In the above description, the amplitude-modulated wave is described using the first sine wave W1 and the second sine wave W2, but the amplitude-modulated wave may be formed by a wave other than a sine wave.

[0061] The driver uses a signal wave with a frequency of 2 Hz to 50 Hz as a modulating wave, and supplies a driving signal having a waveform obtained by amplitude-modulating a sine wave with a frequency of 150 Hz to 300 Hz with the modulating wave to the piezoelectric actuator 101. As a result, a user who touches the tactile sense presentation surface 103b can feel a tapping sensation, making it easier to recognize the vibration point P. Furthermore, this tactile sensation can be adjusted by changing the frequency of the modulating wave.

[0062] (Drive signal 2) The drive signal output from the drive unit to the piezoelectric actuator 101 can have a waveform obtained by amplitude-modulating a sine wave whose frequency is the resonant frequency of the vibration transmission plate 103 with a signal wave having a frequency of 110 Hz or more and 250 Hz or less as a modulating wave. Here, vibrations of 110 Hz or more and 250 Hz or less are vibrations that can be sensed by Pacinian corpuscles, which are receptors in the human skin.

[0063] The resonance frequency of vibration transmission plate 103 is determined by the material of vibration transmission plate 103, and is preferably 20 kHz or more and 110 kHz or less. As shown in Figures 36 and 37, the drive unit can generate a drive signal having an amplitude-modulated wave waveform in which a second sine wave W2 whose frequency is the resonance frequency of vibration transmission plate 103 serves as a carrier wave and a first sine wave W1 whose frequency is 110 Hz or more and 250 Hz or less serves as a modulating wave, and apply this drive signal to piezoelectric actuator 101.

[0064] The modulation depth m (see Equation 2 above) is adjusted within a range of 50% to 100%, and the amplitude modulation difference can be used for tactile expression. Furthermore, since current consumption is reduced where the voltage is reduced, it is also possible to achieve low power consumption. In the above explanation, the amplitude-modulated wave is described using the first sine wave W1 and the second sine wave W2, but the amplitude-modulated wave may be formed by a wave other than a sine wave.

[0065] The driving unit uses a signal wave with a frequency of 110 Hz to 250 Hz as a modulating wave, and supplies a driving signal having a waveform obtained by amplitude-modulating a sine wave whose frequency is the resonant frequency of the vibration transmitting plate 103 with the modulating wave to the piezoelectric actuator 101. As a result, a user who touches the tactile sense presentation surface 103b can feel a sense of levitation. Furthermore, this tactile sensation can be adjusted by changing the frequency of the modulating wave.

[0066] [Drive signal example] Fig. 39 shows an example of an amplitude-modulated wave in which the first sine wave W1 is 2.5 Hz and the second sine wave W2 is 250 Hz. The modulation depth is 100%, and the wave is generated so that it fades in over four waves. Fig. 40 shows an example of an amplitude-modulated wave in which the first sine wave W1 is 25 Hz and the second sine wave W2 is 250 Hz. The modulation depth is 100%, and the wave is generated so that it fades in over five waves and fades out in 1-second increments.

[0067] [Variations] Although the Braille tactile sense generation device 100 is provided with six piezoelectric actuators 101 and generates the tactile sense of six-dot Braille, the present invention is not limited to this. The Braille tactile sense generation device 100 may be provided with at least two piezoelectric actuators 101 and generate the tactile sense of Braille by two or more vibration points P. The Braille tactile sense generation device 100 may be sized so that the tactile sense presentation surface 103b is approximately the same size as a fingertip, but it may also be sized so that the tactile sense presentation surface 103b is approximately the same size as a palm, and used as a Braille tactile sense generation device for young children or those learning Braille. [Explanation of symbols]

[0068] 100...Braille tactile generator 101...Piezoelectric actuator 102...Pedestal 103...Vibration transmission plate 104...First vibration suppression member 105...Second vibration suppression member 111...first piezoelectric actuator chip 112...Second piezoelectric actuator chip 121...First joining area 122...First recess 123...First vibration part 131…Second joining area 132...Second recess 133...Second vibration part 140...Piezoelectric actuator chip 141...Piezoelectric layer 142...Positive inner electrode 143…Negative internal electrode 151...Block 152...Relaxation layer

Claims

1. a plurality of piezoelectric actuators, each of which comprises a piezoelectric layer made of a piezoelectric material, a positive electrode internal electrode provided in the piezoelectric layer, and a negative electrode internal electrode provided in the piezoelectric layer and facing the positive electrode internal electrode via the piezoelectric layer, and when a voltage is applied between the positive electrode internal electrode and the negative electrode, the piezoelectric actuators expand and contract along a direction perpendicular to electrode surfaces of the positive electrode internal electrode and the negative electrode internal electrode, and have a first surface parallel to the electrode surfaces and a second surface parallel to the electrode surfaces and opposite to the first surface; a base including a first bonding surface including a plurality of first bonding regions, each of which is a region where one of the first surfaces is bonded, and a first recess provided around each of the first bonding regions and recessed from the first bonding surface, the base including a plurality of first vibration sections each surrounded by the first recess and having one of the first bonding regions; a vibration transmission plate including a second bonding surface including a plurality of second bonding regions, each of which is a region where one of the second surfaces is bonded, and second recesses provided around each of the second bonding regions and recessed from the second bonding surface, and including a plurality of second vibration portions each surrounded by the second recess and having one of the second bonding regions; Equipped with The first recess and the second recess are gaps, and in top view, the first vibration section overlaps the second vibration section, the first recess overlaps the second recess, and the plurality of piezoelectric actuators are sandwiched between the first vibration section and the second vibration section. Braille tactile generation device.

2. 2. The Braille tactile sensation generating device according to claim 1, a first vibration suppressing member that is filled in the first recess and that suppresses vibration transmission between the plurality of first vibrating portions; a second vibration suppressing member that is filled in the second recess and that suppresses vibration transmission between the plurality of second vibrating portions; A Braille tactile sensation generating device further comprising:

3. 3. The Braille tactile sense generating device according to claim 1 or 2, the plurality of piezoelectric actuators is six piezoelectric actuators; The six piezoelectric actuators are arranged in three rows and two columns when viewed in a direction perpendicular to the electrode surface. Braille tactile generation device.

4. 4. The Braille tactile sense generating device according to claim 1, Each of the plurality of piezoelectric actuators is made up of a plurality of piezoelectric actuator chips, and the plurality of piezoelectric actuator chips are stacked with a direction perpendicular to the electrode surface as the stacking direction. Braille tactile generation device.

5. 5. The Braille tactile sense generating device according to claim 4, Each of the plurality of piezoelectric actuator chips includes a plurality of blocks each including a predetermined number of the positive electrode internal electrodes and the negative electrode internal electrodes, and a buffer layer is provided between the plurality of blocks; The relaxation layer is a piezoelectric layer having a thickness greater than that of the piezoelectric layer between the positive electrode internal electrode and the negative electrode internal electrode in the block. Braille tactile generation device.

6. 6. A Braille tactile sense generating device according to claim 1, The positive electrode internal electrode and the negative electrode internal electrode are further provided with a driving unit that supplies a driving signal having a waveform obtained by amplitude-modulating a sine wave having a frequency of 150 Hz to 300 Hz with a signal wave having a frequency of 2 Hz to 50 Hz as a modulating wave. Braille tactile generation device.

7. a plurality of piezoelectric actuators, each of which comprises a piezoelectric layer made of a piezoelectric material, a positive electrode internal electrode provided in the piezoelectric layer, and a negative electrode internal electrode provided in the piezoelectric layer and facing the positive electrode internal electrode via the piezoelectric layer, and when a voltage is applied between the positive electrode internal electrode and the negative electrode internal electrode, the piezoelectric actuators expand and contract along a direction perpendicular to the electrode surfaces of the positive electrode internal electrode and the negative electrode internal electrode, and have a first surface parallel to the electrode surface and a second surface parallel to the electrode surface and opposite to the first surface; a first bonding surface including a plurality of first bonding regions which are regions where one of the first surfaces is bonded; and a first recess provided around each of the first bonding regions and recessed from the first bonding surface. a vibration transmission plate having a base on which a plurality of first vibration parts are formed, each surrounded by the first recess, and each having one of the first bonding areas; a second bonding surface including a plurality of second bonding areas which are areas to which one of the second surfaces is bonded; and second recesses provided around each of the second bonding areas and recessed from the second bonding surface, and on which a plurality of second vibration parts are formed, each surrounded by the second recess, and each having one of the second bonding areas; wherein the first recess and the second recess are gaps, and in a top view, the first vibration part overlaps the second vibration part, and the first recess overlaps the second recess, and the plurality of piezoelectric actuators are sandwiched between the first vibration part and the second vibration part; a driving unit that supplies a driving signal having a waveform obtained by amplitude-modulating a sine wave having a frequency of 150 Hz or more and 300 Hz or less by a signal wave having a frequency of 2 Hz or more and 50 Hz or less as a modulating wave to the positive internal electrode and the negative internal electrode; A braille tactile sensation generating system comprising:

8. a plurality of piezoelectric actuators, each of which comprises a piezoelectric layer made of a piezoelectric material, a positive electrode internal electrode provided in the piezoelectric layer, and a negative electrode internal electrode provided in the piezoelectric layer and facing the positive electrode internal electrode via the piezoelectric layer; when a voltage is applied between the positive electrode internal electrode and the negative electrode internal electrode, the piezoelectric actuators expand and contract along a direction perpendicular to the electrode surfaces of the positive electrode internal electrode and the negative electrode internal electrode, and have a first surface parallel to the electrode surface and a second surface parallel to the electrode surface and opposite to the first surface; a first bonding surface including a plurality of first bonding regions which are regions where one of the first surfaces is bonded; and first recesses provided around each of the first bonding regions and recessed from the first bonding surface, a vibration transmission plate having a base surrounded by a first bonding surface including a second bonding surface including a second bonding surface and a second bonding surface including a second bonding surface where the second bonding surface is bonded, and a second recess provided around each of the second bonding surfaces and recessed from the second bonding surface, and having a plurality of second vibration sections each surrounded by the second recess and each having one of the second bonding areas, wherein the first recess and the second recess are gaps, and the first vibration section overlaps the second vibration section and the first recess overlaps the second recess in a top view, and the plurality of piezoelectric actuators are sandwiched between the first vibration section and the second vibration section, and a drive signal is supplied to the plurality of piezoelectric actuators individually. A method for driving a braille tactile generation device.

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