JP2017022846A - Vibrator, vibration actuator, and ultrasonic motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibrator capable of efficiently achieving high-speed driving performance with low electric power, while ensuring adhesive strength.SOLUTION: A vibrator 101 includes a piezoelectric element 2, a diaphragm 1 joined to the piezoelectric element 2, and a flexible printed circuit board 3 bonded to the piezoelectric element 2 via an anisotropic conductive material. A joint conducting portion 41 where an electrode portion 31 of the piezoelectric element 2 and an electrode conduction pattern portion 33 of the flexible printed board 3 overlap each other is disposed in an antinode 9 or near the antinode of the vibrator 101. A joint insulating portion 42 where the electrode portion 31 of the piezoelectric element 2 and the electrode conduction pattern portion 33 of the flexible printed circuit 3 do not overlap each other is disposed on a vibration node 8 or near the node of the vibrator 101.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a vibrator, a vibration type actuator, and an ultrasonic motor.

  In an imaging apparatus such as a digital camera or a video camera, an ultrasonic motor, which is a vibration actuator superior to an electromagnetic motor, is used as a driving source for focusing and zooming. An ultrasonic motor is a motor that utilizes the fact that ultrasonic vibration is excited in a vibrator having a piezoelectric element, and the vibrator is pressed against a sliding member, so that the vibrator is relatively moved by frictional force generated between the two. The ultrasonic motor realizes driving so that a plurality of different vibrations such as a vertical vibration and a pendulum vibration are excited in a single vibrator, and these can be combined to continuously move relative to each other. Therefore, in order to obtain the target drive performance, it is necessary to suppress the vibration necessary for driving the vibrator as much as possible. Also, in the case of a plurality of vibration modes, the amplitude of the necessary vibration mode is not suppressed, and the relative movement is efficiently performed by taking a balance such as suppressing the vibration of the vibration mode that does not require an amplitude larger than necessary. It is necessary to realize vibration characteristics.

  Further, in the ultrasonic motor, a high frequency driving voltage is applied to the piezoelectric element using a flexible printed board in order to excite the ultrasonic vibration in the vibrator. Specifically, the electrode portion of the piezoelectric element and the electrode conduction pattern portion of the flexible printed circuit board are joined, and a high frequency driving voltage is applied to the vibrator through the flexible printed circuit board. However, due to the bonding of the flexible printed board to the vibrator, the flexible printed board or the adhesive thereof suppresses vibration of the vibrator.

  Patent Document 1 discloses a vibration type driving device in which a flexible printed circuit board is bonded to the belly of a vibrator, and a boundary between a bonded portion and a non-bonded portion of the flexible printed circuit board is used as a node of the vibrator.

JP 2013-201887 A

  In the vibration type driving device disclosed in Patent Literature 1, the shape of the joint portion of the flexible printed circuit board may be uniquely determined by the layout of the antinodes and nodes of the vibrator. Therefore, the area of the joint portion of the flexible printed board to the vibrator is reduced, which may cause peeling. In this vibration type driving device, an anisotropic conductive material is used for joining the piezoelectric element and the flexible printed board, but the positional relationship between the electrode part of the piezoelectric element and the electrode conductive pattern part of the flexible printed board is unclear. The portion where the electrode portion and the electrode conductive pattern portion overlap has less adhesive and suppresses vibration. On the other hand, in the portion where the electrode portion and the electrode conductive pattern portion do not overlap, there is a large amount of adhesive and vibration is easily suppressed. Depending on the arrangement / shape of the electrode portion of the piezoelectric element and the electrode conduction pattern portion of the flexible printed circuit board, the amount of adhesive on the abdomen of the vibrator may increase and vibration may be easily suppressed.

  Further, it is assumed that the vibrating body has a plurality of types of bending vibration modes such as a primary bending vibration mode and a secondary bending vibration mode. In order to improve driving performance (high speed, low power consumption, etc.) as an ultrasonic motor, the amplitude of the secondary bending vibration mode is better as it is larger, and it is better not to suppress the amplitude. Further, the amplitude of the primary bending vibration mode is larger than necessary, so that the driving performance does not improve and the power consumption increases. Therefore, it is better to suppress the amplitude to an appropriate vibration amplitude. In the vibration type driving device disclosed in Patent Document 1, since the magnitude relationship between the amplitude of the primary bending vibration mode and the amplitude of the secondary bending vibration mode is not considered, high-speed driving performance can be achieved efficiently with low power. Can't get.

  An object of the present invention is to provide a vibrator capable of obtaining high-speed driving performance efficiently with low power while ensuring adhesive strength.

  A vibrator according to an embodiment of the present invention includes a piezoelectric element, a diaphragm bonded to the piezoelectric element, and a substrate bonded to the piezoelectric element via an anisotropic conductive material. A joining conduction portion where the electrode portion of the piezoelectric element and the electrode conduction pattern portion of the substrate overlap is arranged at or near the antinode of vibration of the vibrator. A junction insulating portion where the electrode portion of the piezoelectric element and the electrode conduction pattern portion of the substrate do not overlap each other is disposed at or near the vibration node of the vibrator.

  According to the vibrator of the present invention, high-speed driving performance can be obtained efficiently with low power while securing adhesive strength.

It is a figure which shows the structure of the vibrator | oscillator of this embodiment. It is a figure which shows the vibrator | oscillator with which a vibration type actuator is provided, and a sliding member. It is a figure explaining the vibration mode of a vibrator. It is a figure which shows the structure of the ultrasonic motor incorporating the vibrator | oscillator. It is a figure which shows the structure of the lens-barrel to which an ultrasonic motor is applied. It is a junction electrode arrangement of the flexible printed circuit board in the vibrator. It is AA sectional drawing of FIG. It is a figure explaining the drive characteristic of an ultrasonic motor.

Example 1
FIG. 1 is a diagram illustrating a configuration of a vibrator according to the present embodiment.
A vibrator 101 shown in FIGS. 1A and 1B serves as a drive source for the vibration type actuator of the present embodiment. In the example illustrated in FIG. 1, the vibrator 101 is provided in an ultrasonic motor that functions as a vibration type actuator, and vibrates ultrasonically when a high-frequency driving voltage is applied.

  The vibrator 101 includes a piezoelectric element 2 to which a high-frequency driving voltage is applied during driving, a flexible printed circuit board 3 that is used for voltage application, and a diaphragm 1 that generates ultrasonic vibrations due to the high-frequency driving voltage applied to the piezoelectric element 2. Is provided. The piezoelectric element 2 and the diaphragm 1 are joined with an adhesive. Two vibration protrusions 1 a are formed side by side on the diaphragm 1. The piezoelectric element 2 and the flexible printed circuit board 3 for applying a high frequency driving voltage to the piezoelectric element 2 are joined via an anisotropic conductive material, and an electrode portion (not shown) of the piezoelectric element 2 and the flexible printed circuit board 3 electrode conduction pattern portions (not shown) are conducted.

FIG. 2 is a diagram illustrating a vibrator and a sliding member included in the vibration type actuator.
The sliding member 4 shown in FIGS. 2A and 2B is in frictional contact with the vibrator 101. A high frequency driving voltage is applied to the piezoelectric element 2 in the vibrator 101 through the flexible printed circuit board 3 to cause the vibrator 101 to excite ultrasonic vibration. By pressing (not shown) the vibrator 101 on the sliding member, the vibrator 101 and the sliding member 4 are relatively moved in the X direction by a frictional force generated between them.

FIG. 3 is a diagram illustrating the vibration mode of the vibrator.
The ultrasonic motor generates a vibration for driving by applying a plurality of desired vibration modes by applying a high-frequency drive voltage of a specific frequency to the piezoelectric element of the vibrator and superimposing these vibration modes. . In this embodiment, the vibrator 101 and the sliding member 4 as shown in FIG. 2 are used to excite the vibrator 101 in the two bending vibration modes shown in FIGS. 3 (A) and 3 (B).

  The vibration mode shown in FIG. 3A is a bending vibration mode (first bending vibration mode) of the vibrator 101 in the short direction, and a positive voltage or a negative voltage is simultaneously applied to two electrodes of PZT. Each operation is shown. The vibration mode shown in FIG. 3B is a bending vibration mode in the longitudinal direction of the vibrator 101 (second bending vibration mode). Similarly, each of the two electrodes of PZT is simultaneously positive and negative or negative. Each operation is shown when positive and different voltages are applied. 3A and 3B, the directions indicating the vibrator 101 are orthogonal to each other. In this embodiment, the bending directions of the two bending vibration modes are orthogonal to each other.

  The shape of the vibrator 101 is designed so that the resonance frequencies of the two vibration modes match or are close to each other. In the first bending vibration, the vibration protrusion 1a is disposed at or near the position of the vibration antinode 6. The first protrusion vibration causes the vibration protrusion 1a to move up and down as indicated by 7 in the Z direction. Reciprocate. This is the drive-up movement component of the drive.

  In the second bending vibration, the position of the vibration protrusion 1a is the position that becomes the vibration node 8 or in the vicinity of the node, and the vibration protrusion 1a causes the pendulum by using the position at which the vibration protrusion 1a is disposed as a fulcrum. Move and do 10 reciprocations in the X direction. This is the feed movement component of the drive.

  Reference numeral 11 denotes a first bending vibration node of the vibrator 101. Reference numeral 9 denotes an antinode of the second bending vibration of the vibrator 101. In order to realize the second bending vibration mode, the piezoelectric element 2 is polarized in two layers in the longitudinal direction. By simultaneously exciting two vibration modes (first bending vibration mode and second bending vibration mode) and superimposing two orthogonal vibration modes, the vibration protrusion 1a can move up and down as indicated by 13 in the XZ plane. Elliptic motion is performed as a combination of motion and pendulum motion. By this elliptical motion 13, the vibrator 101 can be driven to move relative to the sliding member 4 in pressure contact with the vibrator 101.

FIG. 4 is a diagram showing a configuration of an ultrasonic motor incorporating a vibrator.
The unit base 14 supports the entire ultrasonic motor. The unit base 14 has a sliding member 4 fixed to the lower side and a top plate 15 fixed to the upper side. Four rolling members 16 are incorporated in the top plate 15. The rolling member 16 rolls while being sandwiched between the top plate 15 and the guide member 17. As a result, the guide member 17 can move in the X direction as indicated by the arrow 17a.

  The guide member 17 is provided with four guide grooves (not shown). The top plate 15 is also provided with the same four guide grooves (not shown), and the rolling member 16 is incorporated therein. The vibrator holding member 18 is attached to the guide member 17.

  The vibrator holding member 18 includes a piezoelectric element 2 to which a high-frequency driving voltage is applied during driving and a vibrator 101 including a vibration plate 1 that generates ultrasonic vibrations due to the high-frequency driving voltage applied to the piezoelectric element 2 with an adhesive or the like. It is attached and held. A pressure mechanism (not shown) that pressurizes the vibrator 101 is provided inside the guide member 17. The pressurizing mechanism deforms the vibrator holding member 18 having a spring member and pressurizes the vibrator 101 attached thereto to the sliding member 4.

  The ultrasonic motor has the above-described configuration, and the pressing mechanism (not shown) presses the vibrator 101 against the sliding member 4, so that the vibration protrusion 1a is in frictional contact with the sliding member 4. To do. Then, by generating ultrasonic vibration in the vibrator 101, a driving force is generated by friction between the vibration projection 1 a and the sliding member 4, and the vibrator 101 moves in the X direction with respect to the sliding member 4. In this embodiment, the vibrator 101 is moved and the sliding member 4 is fixed. However, the vibrator 101 may be fixed and the sliding member 4 may be moved.

FIG. 5 is a diagram showing a configuration of a lens barrel to which an ultrasonic motor is applied.
The lens barrel 21 shown in FIG. 5 uses an ultrasonic motor as a focusing drive source. As the imaging optical system of the lens barrel 21, a first group and a second group lens barrel 22 are provided from the subject side. The lens barrel 21 is provided with a focus lens 23 and a lens moving frame 24 that holds the focus lens 23. The lens barrel 21 is provided with a fourth group and a fifth group lens barrel 25. A fixed lens is incorporated in the first group, second group lens barrel 22, fourth group, and fifth group lens barrel 25.

  Two main guide bars 26 for moving the lens moving frame 24 back and forth in the direction of the optical axis 29 are attached to the inner wall of the lens barrel 21 in parallel with the optical axis 29. A unit base 14 is attached inside the lens barrel 21 so that the guide member 17 can move in the direction of the optical axis 29. The guide member 17 and the lens moving frame 24 are connected by a connecting member 27, the driving force of the vibrator 101 is transmitted to the lens moving frame 24, and the focus lens 23 can be moved in the direction of the optical axis 29.

FIG. 6 is a diagram for explaining the arrangement of the joint electrodes of the flexible printed circuit board in the vibrator of this embodiment.
In this embodiment, an anisotropic conductive material is used for joining the piezoelectric element 2 and the flexible printed circuit board 3. 6A and 6B are top views of the vibrator 101 on the piezoelectric element 2 side. 6A shows the electrode part 31 and the ground electrode part 32 of the piezoelectric element 2 and the flexible printed circuit board 3 joined to the piezoelectric element 2. FIG.

  FIG. 6B shows an electrode pattern of the flexible printed circuit board 3. Specifically, FIG. 6B shows the positional relationship between the electrode portion 31 and the ground electrode portion 32 of the piezoelectric element 2 and the electrode conduction pattern portion 33 and the earth electrode conduction pattern portion 34 of the flexible printed circuit board 3. Yes. FIG. 6C shows the operation of the vibrator 101. FIG. 6C shows the operation of the second bending vibration mode in the longitudinal direction of the vibrator 101 described with reference to FIG.

  In FIG. 6, an antinode 6 is an antinode of the first bending vibration mode. The node 11 is a node in the first bending vibration mode. An antinode 9 is an antinode of the second bending vibration mode. The node 8 is a node in the second bending vibration mode.

  In this embodiment, in order to improve the drive performance (maximum speed, drive torque) as an ultrasonic motor, the vibration characteristic of the vibrator 101 is the second with respect to the amplitude of the first bending vibration mode (vertical vibration). Increase the amplitude of the bending vibration mode (pendulum vibration). In order to improve the drive performance (high speed, low power consumption, etc.), the amplitude of the second bending vibration mode (pendulum vibration) is increased to increase the feed motion component of the drive. On the other hand, the amplitude of the first bending vibration mode (vertical vibration) is a driving push-up motion component and needs a certain amount of magnitude, but if it is too large, the driving performance (maximum speed, driving torque) does not increase. Only the power consumption becomes large. Therefore, the amplitude of the first bending vibration mode (vertical vibration) is set to an appropriate value that is smaller than the amplitude of the second bending vibration mode (pendulum vibration). For this reason, in the vibrator 101, each of the vibration plate 1, the piezoelectric element 2, and the flexible printed circuit board 3 has an amplitude of the second bending vibration mode with respect to the amplitude of the first bending vibration mode of the piezoelectric element 2. Is set to be large.

  A configuration for increasing the amplitude of the second bending vibration mode (pendulum vibration) will be described below. The piezoelectric element 2 includes two polarized electrode portions 31 and one ground electrode portion 32. The flexible printed board 3 includes an electrode conduction pattern portion 33 and a ground electrode conduction pattern portion 34. When the flexible printed circuit board 3 is bonded to the piezoelectric element 2, the bonding conductive part 41 where the electrode part 31 of the piezoelectric element 2 and the electrode conductive pattern part 33 of the flexible printed circuit board 3 overlap is arranged in the regions 41 a and 41 b. The regions 41a and 41b are regions in the vicinity of the antinode 9 or the antinode 9 of the second bending vibration mode of the vibrator. Ideally, the joining conduction portion 41 is desired to be disposed on the antinode 9 of the second bending vibration mode of the vibrator, but is disposed in the vicinity thereof due to misalignment or the like.

  A bonding insulating portion 42 in which the electrode portion 31 of the piezoelectric element 2 and the electrode conduction pattern portion 33 of the flexible printed circuit board 3 do not overlap each other is disposed at or near the node 8 of the second bending vibration mode of the vibrator.

FIG. 7 is a cross-sectional view taken along the line AA of FIG.
The junction conduction part 41 is an area where the electrode part 31 of the piezoelectric element 2 and the electrode conduction pattern part 33 of the flexible printed circuit board 3 overlap. Further, the bonding insulating portion 42 is a region where the electrode portion 31 of the piezoelectric element 2 and the electrode conduction pattern portion 33 of the flexible printed circuit board 3 do not overlap. The bonding insulating portion 42 includes a portion where the electrode portion 31 of the piezoelectric element 2 and the electrode conduction pattern portion 33 of the flexible printed circuit board 3 are not provided. The anisotropic conductive material 35 used for joining has electrical anisotropy. That is, the anisotropic conductive material 35 has a conductive filler 37 inside the adhesive 36, and is electrically conductive in the thickness direction of the bonded portion 40 by thermal bonding, and with respect to the surface direction of the bonded portion. Is insulative.

  The conductive filler 37 is made of a conductive material, and is crushed between the electrode portion 31 and the electrode conductive pattern portion 33 so that the electrodes are electrically connected in the Z direction in the drawing. The X direction in the drawing of the bonding insulating portion 42 where the conductive filler 37 is not crushed is insulated. As a result, the two electrode portions are not electrically connected to each other.

  The adhesive 36 is a viscoelastic material that easily suppresses vibration. In this example, the adhesive 36 is a compatible rubber resin. The junction conduction part 41 has a small amount of the adhesive 36 corresponding to the thickness of each electrode part, and is a layer having a thickness of about 5 μm in this example. Therefore, the suppression of the vibration of the vibrator 101 is small. On the other hand, since the bonding insulating portion 42 has no electrode, the adhesive 36 is also thick, in this example, about 27 μm. Therefore, it is easy to suppress the vibration of the vibrator 101. Considering suppression of the vibration of the entire vibrator 101, it is advantageous that the shape of the flexible printed circuit board 3 is as small as possible. However, considering the bonding strength, an appropriate size is required.

  The flexible printed circuit board 3 according to the present embodiment has such a size that the vibration of the vibrator 101 can be suppressed as much as possible and the adhesive strength can be secured. And the junction conduction | electrical_connection part 41 with which the electrode part 31 and the electrode conduction | electrical_connection pattern part 33 overlap is arrange | positioned in the antinode 9 of the 2nd bending vibration mode of the vibration of the vibrator | oscillator 101, or its vicinity. In addition, a bonding insulating portion 42 in which the electrode portion 31 of the piezoelectric element 2 and the electrode conduction pattern portion 33 of the flexible printed circuit board 3 do not overlap each other is disposed at or near the node 8 of the second bending vibration mode of the vibrator. .

  In other words, in the present embodiment, an area with a small amount of the adhesive 36 is disposed in the portion of the antinode 9 in the second bending vibration mode in which the amplitude is increased, thereby minimizing the antivibration of the abdomen and making the adhesive 36 easy to suppress the vibration. The region having a large amount of the noise is disposed at the portion of the node 8 in the second bending vibration mode having a small amplitude. Thereby, it is possible to realize the vibrator 101 having a small vibration suppression effect with respect to the vibration characteristics for which the amplitude of the second bending vibration mode (pendulum vibration) is desired to be increased.

  Next, with the vibration characteristics of two bending vibration modes in which the bending directions are orthogonal, the amplitude of the first bending vibration mode (vertical vibration) is smaller than the amplitude of the second bending vibration mode (pendulum vibration) and is appropriate. A configuration to be sized will be described.

  When the flexible printed circuit board 3 is bonded to the piezoelectric element 2, the bonding insulating part 42 in which the electrode part 31 of the piezoelectric element 2 and the electrode conduction pattern part 33 of the flexible printed circuit board 3 do not overlap each other is in the first bending vibration mode of the vibrator. It arrange | positions in the stomach | belt 6 or its vicinity. Further, the bonding conduction portion 41 where the electrode portion 31 of the piezoelectric element 2 and the electrode conduction pattern portion 33 of the flexible printed circuit board 3 overlap each other is connected to the antinode 6 of the first bending vibration mode and the antinode of the second bending vibration mode. It is arranged at a position where 9 intersects or a region in the vicinity thereof (region 41b). In other words, in two orthogonal bending modes, the bonding conduction portion 41 is disposed on the antinode 9 of the second bending vibration mode in which the vibration amplitude is desired to be increased, and the bonding insulating portion 42 is provided on the antinode 6 of the first bending vibration mode. To increase the degree of vibration suppression.

  In order to improve the driving performance (high speed, low power consumption, etc.), it is desired to increase the amplitude of the second bending vibration mode (pendulum vibration) as much as possible, so that the suppression of vibration is minimized. On the other hand, the amplitude of the first bending vibration mode (vertical vibration) needs to be large to a certain extent, but if it is too large, only the power consumption increases, so that suppression to become an appropriate vibration amplitude is added. Thus, the degree of vibration suppression is changed. By adopting this configuration, it is possible to prevent the amplitude of the second bending vibration mode (pendulum vibration) from being reversed and smaller than the amplitude of the first bending vibration mode (vertical vibration). doing.

  Note that one of the configuration in which the suppression of the vibration in the second bending vibration mode described above is reduced and the amplitude in the first bending vibration mode is smaller than the amplitude in the second bending vibration mode and is appropriately set. May be adopted.

FIG. 8 is a diagram for explaining drive characteristics of an ultrasonic motor to which the vibrator of this embodiment is applied.
The graph 51 shows the drive characteristics of the ultrasonic motor. The horizontal axis indicates the driving frequency, and the vertical axis indicates the driving speed when the driving frequency is swept. The broken line 53 shows the drive characteristic of the conventional ultrasonic motor which is not devising the arrangement of the joint electrodes of the flexible printed circuit board. A solid line 54 indicates the drive characteristics of the ultrasonic motor of this embodiment. In the ultrasonic motor of the present embodiment, the speed is higher than the driving characteristics of the conventional ultrasonic motor at any driving frequency.

  The graph 52 shows the power consumption when the ultrasonic motor is driven at a certain speed. Reference numeral 55 denotes the power consumption of a conventional ultrasonic motor. Reference numeral 56 denotes the power consumption of the ultrasonic motor of this embodiment. The power consumption of the ultrasonic motor of this embodiment is lower than the power consumption of the conventional ultrasonic motor. As described above, according to the present invention, it is possible to realize an efficient vibration type actuator capable of obtaining high speed driving performance with low power.

1 Diaphragm 2 Piezoelectric element 3 Flexible printed circuit board

Claims (8)

A piezoelectric element;
A diaphragm bonded to the piezoelectric element;
A substrate bonded to the piezoelectric element via an anisotropic conductive material,
A bonding conduction portion in which the electrode portion of the piezoelectric element and the electrode conduction pattern portion of the substrate overlap is disposed at or near the vibration antinode of the vibrator,
A vibrator characterized in that a junction insulating part in which the electrode part of the piezoelectric element and the electrode conduction pattern part of the substrate do not overlap each other is arranged at or near a vibration node of the vibrator. The vibration mode of the vibrator has first and second bending vibration modes orthogonal to each other,
The vibrator according to claim 1, wherein an amplitude of vibration in the second bending vibration mode is set to be larger than an amplitude of vibration in the first bending vibration mode. The bonding conduction portion is disposed at or near the antinode of the vibration in the second bending vibration mode;
The vibrator according to claim 2, wherein the junction insulating portion is disposed in or near a vibration node of the second bending vibration mode. 4. The vibrator according to claim 2, wherein the bonding insulating portion is disposed at or near an antinode of vibration in the first bending vibration mode. 5. 5. The junction conduction portion is disposed at a position where the antinode of the vibration in the first bending vibration mode and the antinode of the vibration in the second bending vibration mode intersect or in the vicinity of the position. The vibrator described in 1. The vibrator according to claim 1, wherein the substrate is a flexible printed substrate that applies a driving voltage to the piezoelectric element. The vibrator according to any one of claims 1 to 6,
A vibration type actuator comprising: a sliding member with which the vibrator frictionally contacts. The ultrasonic motor that functions as a vibration type actuator according to claim 7, wherein the vibrator vibrates ultrasonically when a driving voltage is applied.

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