JP6273137B2 - Motor and device with motor - Google Patents

Description

  The present invention relates to an ultrasonic motor that drives a driven portion by generating vibration in a pressed vibrator, and a device with an ultrasonic motor such as a lens device using the ultrasonic motor.

  Conventionally, for example, an ultrasonic motor has been adopted as a driving source for a camera or a lens, taking advantage of silent operation, driving from low speed to high speed, and high torque output. The ultrasonic motor disclosed in Patent Document 1 includes a square bar-like driven part and a vibrator including a contact part that comes into contact with the driven part. The contact portion of the vibrator is pressurized and in contact with the driven portion. When ultrasonic vibration is excited in the vibrator, elliptical motion occurs in the contact portion of the vibrator, and the driven portion vibrates. Move relative to the child.

JP 2012-125114 A

However, in the ultrasonic motor disclosed in Patent Document 1, since the two contact portions are arranged in the relative movement direction, the size in the relative movement direction tends to increase. The present invention, this problem has been made to solve, and to provide that the can makes the chromophore at the distal end over data, etc. to reduce the size of the relative movement direction.

Motors of the present invention is the electrode area which is vertically and horizontally divided into two parts in one surface forming a piezoelectric element on the other surface of the one electrode regions are formed, it is fixed to the vibrating elastic member wherein the piezoelectric element vibration of the secondary bending vibration mode and the first-order torsional vibration mode is excited by a predetermined phase shift, twisting the loop position of the secondary bending vibration mode of the primary and and vibrating the elastic member having two contact portions provided at the intersection of the node positions of the vibration mode, have a contact surface between the two contact portions, it moves relative to the vibrating elastic member by pre Kifu dynamic And a driven part.

According to the present invention, it is possible to provide two alignment direction of the contact portion and the relative movement and can be made to the orthogonal direction, makes the chromophore at the distal end over data can reduce the size of the relative movement direction by the arrangement.

1 is a perspective view of a vibration elastic body to which a piezoelectric element of an ultrasonic motor according to a first embodiment of the present invention is fixed. FIG. The figure explaining the vibration mode of the vibration elastic body of Example 1 of this invention. The figure explaining the vibration mode of the vibration elastic body of Example 1 of this invention. The figure explaining the electrode of the piezoelectric element of Example 1 of this invention, and the pattern of polarization. The figure explaining the alternating voltage pattern applied to the piezoelectric element of Example 1 of this invention. The figure explaining the relationship between the voltage applied to the piezoelectric element of Example 1 of this invention, and a deformation | transformation of a vibration elastic body. The figure explaining the relationship between the voltage applied to the piezoelectric element of Example 1 of this invention, and a deformation | transformation of a vibration elastic body. The figure for demonstrating the shape and dimension of a vibration elastic body of Example 1 of this invention. 1 is a developed perspective view of an ultrasonic motor according to a first embodiment of the present invention. FIG. 3 is an embedded diagram of the ultrasonic motor according to the first embodiment of the present invention. The figure for demonstrating the shape and dimension of a vibration elastic body of Example 2 of this invention. The figure for demonstrating the shape and dimension of a vibration elastic body of Example 3 of this invention. The figure explaining the pattern of the electrode and polarization of the piezoelectric element of Example 4 of this invention. Sectional drawing of an example of the lens-barrel incorporating the ultrasonic actuator containing the ultrasonic motor of this invention.

In the present invention, a piezoelectric element fixed to the vibrating elastic vibration of the secondary bending vibration mode and the first-order torsional vibration mode is excited with a predetermined phase shift, the bending vibration mode antinode position and the Two contact portions of the vibrating elastic body are provided at or near the intersection with the node position of the torsional vibration mode. The driven portion has a contact surface between the two contact portions, it moves relative to the vibrating elastic member by pre Kifu movement. The secondary bending vibration mode is a vibration mode having three nodes and two antinodes, and the primary torsional vibration mode is a vibration mode having one node and two antinodes.

  Embodiments of the present invention will be described below with reference to the drawings. In the present specification, a direction in which a vibration elastic body 2 (to be described later) and the driven unit 1 relatively move is defined as an X direction. In addition, a direction in which two contact portions 2a and 2b described later are arranged is a Y direction. Further, a direction perpendicular to the X direction and the Y direction is defined as a Z direction. In the Z direction, the direction from the vibration elastic body 2 to the driven body 1 is defined as the + Z direction, and the direction from the driven body 1 to the vibration elastic body 2 is defined as the -Z direction. In the drawings, the same members are indicated by the same symbols.

[Example 1]
FIG. 1 is a perspective view of a vibrating elastic body to which a piezoelectric element of an ultrasonic motor that is Embodiment 1 of the present invention is fixed. 2 is a vibration elastic body. Two projecting portions 2c and 2d project in the + Z direction on the flat plate portion 2g at the center of the vibration elastic body 2. Reference numerals 2a and 2b are contact portions formed on the upper end surfaces of the protrusions 2c and 2d, and are surfaces that come into contact with a contact surface 1a of the driven body 1 to be described later with reference to FIG. The two contact portions 2a and 2b are formed on the same plane, and are finished to a uniform surface by polishing or the like during the manufacturing process in order to improve the contact state with the contact surface 1a of the driven body 1.

  On the other hand, the piezoelectric element 3 is pressure-bonded with an adhesive or the like on the back surface side of the flat plate portion 2g (the surface side opposite to the surface on which the two protruding portions are formed). The method of press-bonding the back surface of the flat plate portion 2g and the piezoelectric element 3 is not limited as long as the press-bonding is performed. The piezoelectric element 3 is excited by applying an AC voltage pattern to be described later with reference to FIG. 4, and two vibration modes to be described later are excited on the vibration elastic body 2 to which the piezoelectric element 3 is pressure-bonded. At this time, by setting the vibration phases of the two vibration modes to have a desired phase difference, an elliptical motion that is displaced in the XZ plane is generated in the contact portions 2a and 2b. By generating this elliptical motion by the vibration elastic body 2 and transmitting it to the contact surface 1a of the driven body 1, the vibration elastic body 2 and the driven body 1 can be relatively moved in the X direction.

  Next, two fixing portions 2f for joining to a holding portion (not shown) are formed at both ends of the flat plate portion 2g. The vibration elastic body 2 is fixed to the holding portion (not shown) by screw fixing, welding, adhesion, or the like in the fixing portion 2f. If the vibration elastic body 2 and the holding portion (not shown) are fixed, The method is not limited. Arm portions 2e are formed between the two fixing portions 2f and the flat plate portion 2g, and the flat plate portion 2g is fixed to a holding portion (not shown) via the arm portions 2e. As shown in FIG. 1, the arm portion 2e has a narrow shape with respect to the flat plate portion 2g and the fixed portion 2f in order to make it difficult to transmit the vibration generated in the flat plate portion 2g to the fixed portion 2f. In other words, a connecting configuration in which the holding portion (not shown) does not inhibit the vibration generated in the flat plate portion 2g is realized by the arm portion 2e.

FIGS. 2-1 and 2-2 are diagrams for explaining the vibration modes of the vibration elastic body in the ultrasonic motor that is Embodiment 1 of the present invention. In this ultrasonic motor, an AC voltage pattern is applied to the piezoelectric element 3 to excite the secondary bending vibration mode and the primary torsional vibration mode in the vibration elastic body 2.

  FIG. 2-1 (A), FIG. 2-1 (C), and FIG. 2-1 (E) are diagrams showing a secondary bending vibration mode. FIG. 2-1 (A) is a perspective view, FIG. 2-1 (C) is a view seen from the + X direction, and FIG. 2-2 (E) is a view seen from the −Y direction. The secondary bending vibration mode has three positions including the center in the Y direction and approximately 1/8 position from both ends inward, and approximately 1/3 position inward from both ends in the Y direction. Is a vibration mode that bends and displaces in the YZ plane having the two antinodes. By exciting such a secondary bending vibration mode, the two contact portions 2a and 2b reciprocate in the Z direction in opposite phases. Thereby, the two contact portions 2a and 2b can alternately repeat contact and retraction with respect to a contact surface 1a (see FIG. 8) of the driven body 1 described later. Hereinafter, this secondary bending vibration mode is referred to as a push-up vibration mode.

  FIG. 2-1 (B), FIG. 2-1 (D), and FIG. 2-2 (F) are diagrams illustrating the first torsional vibration mode. FIG. 2-1 (B) is a perspective view, FIG. 2-1 (D) is a view seen from the + X direction, and FIG. 2-2 (F) is a view seen from the −Y direction. The first-order torsional vibration mode is a first-order torsional vibration mode in which the center in the X direction and the center in the Y direction are simultaneously node positions and are displaced in three dimensions of X, Y, and Z. By exciting such a primary torsional vibration mode, the two contact portions 2a and 2b reciprocate in the X direction in opposite phases. Thereby, when the contact surface 1a of the driven body 1 is in frictional contact, one of the two contact portions 2a and 2b is displaced in the X direction, so that the driven body 1 and A force for relative movement in the X direction with the vibrating elastic body 2 is generated. Hereinafter, this primary torsional vibration mode is referred to as a feed vibration mode.

  By combining the push-up vibration mode and the feed vibration mode with a predetermined phase difference, the two contact portions 2a and 2b are excited with elliptical vibration that is displaced in the XZ plane. At this time, the two contact portions 2a and 2b have elliptical vibrations in opposite phases. Therefore, the two contact portions 2a and 2b alternately contact and retreat with respect to a contact surface 1a of the driven body 1 to be described later, and at the time of contact, generate a frictional force in the same direction in the X direction. become. Thereby, since the two contact portions 2a and 2b alternately generate driving force, a high-speed ultrasonic motor that efficiently generates driving force can be realized. Further, since the two contact portions 2a and 2b are arranged in the Y direction orthogonal to the relative movement direction, an ultrasonic motor having a small size in the X direction that is the relative movement direction can be realized.

  FIG. 3 is a diagram for explaining the electrode and polarization pattern of the piezoelectric element 3 of this embodiment. 3A is a view of the piezoelectric element 3 viewed from the −Z side, and FIG. 3B is a view of the piezoelectric element 3 viewed from the + Z side. In FIG. 3A, on the surface of the piezoelectric element 3 on the −Z side, four electrode regions (that is, divided into two in the vertical and horizontal XY directions each having a center in the X direction and a center in the Y direction as boundary lines) , Electrode region 3c, electrode region 3d, electrode region 3e, and electrode region 3f) are formed. On the other hand, in FIG. 3B, one non-divided electrode region 3g is formed on the surface of the piezoelectric element 3 on the + Z side. Therefore, the piezoelectric element 3 of the present embodiment is composed of a single plate piezoelectric element in which electrode regions are provided on both sides. In FIG. 3, the piezoelectric element 3 is subjected to polarization processing of different polarities on the −Y side and the + Y side with the center in the Y direction as a boundary line. That is, the piezoelectric elements have different polarization directions in two regions arranged in a direction orthogonal to the relative movement direction.

  Here, the electrode region 3g is electrically connected to the ground potential. Since the electrode region 3g is a surface in contact with the vibration elastic body 2, it may be conducted to the ground potential via the vibration elastic body 2. On the other hand, the AC voltage pattern VA is applied in the same phase to the electrode region 3c and the electrode region 3d, and the AC voltage pattern VB having a phase shifted from the AC voltage pattern VA is applied to the electrode region 3e and the electrode region 3f. Since the piezoelectric element 3 has a + Z side surface connected to the ground potential and a −Z side surface to which the AC voltage pattern VA or the AC voltage pattern VB is applied, a potential difference occurs between the front surface and the back surface, and the piezoelectric element 3 tends to expand and contract. . On the other hand, since the surface on the + Z side is fixed to the vibration elastic body 2, expansion and contraction is hindered. Due to the difference in expansion and contraction between the front surface and the back surface, the piezoelectric element 3 is bent out of plane. The direction of bending differs depending on the direction of polarization and the direction of applied voltage. 3 is applied to the piezoelectric element having the electrode and the polarization pattern shown in FIG. 3, so that the combined vibration of the push-up vibration mode and the feed vibration mode is applied to the vibration elastic body 2. Is excited. The piezoelectric element 3 of the present embodiment will be described as a single-plate piezoelectric element, but the effect of the present invention is not limited to the single-plate piezoelectric element, and may be constituted by a laminated piezoelectric element in which a plurality of piezoelectric elements are stacked. Similar effects can be obtained.

  FIG. 4 is a diagram for explaining an AC voltage pattern applied to the piezoelectric element of this embodiment. FIG. 4A shows an AC voltage pattern applied when the driven body 1 moves relative to the vibration elastic body 2 in the −X direction. FIG. 4B shows a case where the driven body 1 is a vibration elastic body. 2 is an AC voltage pattern applied when moving relative to 2 in the + X direction. FIGS. 5A and 5B are diagrams illustrating the relationship between the voltage applied to the piezoelectric element 3 and the deformation of the vibration elastic body 2. An AC voltage pattern applied to the piezoelectric element 3 and a state of deformation of the vibration elastic body corresponding to the AC voltage pattern will be described with reference to FIGS. 4, 5-1, and 5-2.

  FIG. 4A is an AC voltage pattern applied when the driven body 1 moves relative to the vibration elastic body 2 in the −X direction. In FIG. 4A, the horizontal axis represents time, and the vertical axis represents voltage. VA is an alternating voltage pattern applied to the electrode region 3c and the electrode region 3d, and VB is an alternating voltage pattern applied to the electrode region 3e and the electrode region 3f. In the time on the horizontal axis, T1 is a period of the first quarter cycle when one cycle of the AC voltage is divided into four. T2 is a period of the second quarter cycle, T3 is a period of the third quarter cycle, and T4 is a period of the fourth quarter cycle. In a period T1 in FIG. 4A, a voltage of + VDD is applied to the alternating voltage pattern VA, and a voltage of + VDD is also applied to the alternating voltage pattern VB.

  FIG. 5A shows voltages applied to the four electrode regions (electrode region 3c, electrode region 3d, electrode region 3e, and electrode region 3f) of the piezoelectric element 3 in the period T1. A voltage of + VDD is applied to all of the electrode region 3c, electrode region 3d, electrode region 3e, and electrode region 3f. Here, the regions corresponding to the electrode region 3d and the electrode region 3e and the regions corresponding to the electrode region 3e and the electrode region 3f have different polarization treatment directions. Therefore, the vibration elastic body 2 undergoes secondary bending deformation in the YZ plane as shown in FIG. Since the two contact portions 2a and 2b are provided at the antinodes of the secondary bending deformation, one contact portion 2a is displaced in the -Z direction, and the other contact portion 2b is displaced in the + Z direction.

  In a period T2 in FIG. 4A, a voltage of −VDD is applied to the AC voltage pattern VA, and a voltage of + VDD is applied to the AC voltage pattern VB. FIG. 5-1 (C) shows voltages applied to the four electrode regions (electrode region 3c, electrode region 3d, electrode region 3e, and electrode region 3f) of the piezoelectric element 3 in the period T2. A voltage of −VDD is applied to the electrode region 3c and the electrode region 3d, and a voltage of + VDD is applied to the electrode region 3e and the electrode region 3f. Here, the regions corresponding to the electrode region 3d and the electrode region 3e and the regions corresponding to the electrode region 3e and the electrode region 3f have different polarization treatment directions. Therefore, as shown in FIG. 5D, the vibration elastic body 2 has a primary position that is displaced in the three dimensions of X, Y, and Z, with the center in the X direction and the center in the Y direction at the same time. Torsional deformation occurs. Since the two contact portions 2a and 2b are provided at the antinodes of the primary torsional deformation, one contact portion 2a is displaced in the -X direction, and the other contact portion 2b is displaced in the + X direction.

In a period T3 in FIG. 4A, a voltage of −VDD is applied to the AC voltage pattern VA, and a voltage of −VDD is also applied to the AC voltage pattern VB. FIG. 5-2 (E) shows voltages applied to the four electrode regions (electrode region 3c, electrode region 3d, electrode region 3e, and electrode region 3f) of the piezoelectric element 3 in the period T3. A voltage of −VDD is applied to all of the electrode region 3c, the electrode region 3d, the electrode region 3e, and the electrode region 3f. Here, the regions corresponding to the electrode region 3d and the electrode region 3e and the regions corresponding to the electrode region 3e and the electrode region 3f have different polarization treatment directions. Therefore, the vibration elastic body 2 undergoes secondary bending deformation in the YZ plane as shown in FIG. Since the two contact portions 2a and 2b are provided at the antinodes of the secondary bending deformation, one contact portion 2a is displaced in the + Z direction, and the other contact portion 2b is displaced in the -Z direction.

  In a period T4 in FIG. 4A, a voltage of −VDD is applied to the AC voltage pattern VA, and a voltage of + VDD is applied to the AC voltage pattern VB. FIG. 5-1 (C) shows voltages applied to the four electrode regions (electrode region 3c, electrode region 3d, electrode region 3e, and electrode region 3f) of the piezoelectric element 3 in the period T2. A voltage of + VDD is applied to the electrode region 3c and the electrode region 3d, and a voltage of −VDD is applied to the electrode region 3e and the electrode region 3f. Here, the regions corresponding to the electrode region 3d and the electrode region 3e and the regions corresponding to the electrode region 3e and the electrode region 3f have different polarization treatment directions. Therefore, as shown in FIG. 5-2 (G), the vibration elastic body 2 has a primary position that is displaced in the three dimensions of X, Y, and Z, with the center in the X direction and the center in the Y direction at the same time. Torsional deformation occurs. Since the two contact portions 2a and 2b are provided at the antinodes of the primary torsional deformation, one contact portion 2a is displaced in the + X direction, and the other contact portion 2b is displaced in the -X direction.

  As described above with reference to FIGS. 4A, 5-1, and 5-2, the vibration elastic body 2 is sequentially deformed by changing the period T 1 → the period T 2 → the period T 3 → the period T 4 and thereby the contact portion. 2a continuously performs −Z displacement → + X displacement → + Z displacement → −X displacement to make an elliptical motion in the XZ plane. On the other hand, the contact portion 2b continuously performs + Z displacement → −X displacement → −Z displacement → + X displacement to make an elliptical motion in the XZ plane. Thus, since the contact part 2a and the contact part 2b are always displaced in the opposite direction, the contact part 2a and the contact part 2b are elliptical motions of opposite phases. Both the contact portion 2a and the contact portion 2b perform + Z displacement during the transition from + X displacement to -X displacement. That is, the contact part 2 a and the contact part 2 b transmit a force in the −X direction to the driven body 1 while being in contact with the contact surface 1 a of the driven body 1. Thereby, the driven body 1 moves relative to the vibration elastic body 2 in the −X direction.

  FIG. 4B is an AC voltage pattern applied when the driven body 1 moves relative to the vibration elastic body 2 in the + X direction. The difference from FIG. 4A is that the AC voltage pattern of period T4 is applied next to the AC voltage pattern of period T1, and the AC voltage pattern of period T2 is applied next to the AC voltage pattern of period T3. . That is, application is performed in the order of the period T1, the period T4, the period T3, and the period T4. Therefore, by sequentially deforming the vibration elastic body 2 in the period T1, the period T4, the period T3, and the period T2, the contact portion 2a continuously performs −Z displacement → −X displacement → + Z displacement → + X displacement, and the XZ plane. The ellipse moves inside. On the other hand, the contact portion 2b continuously performs + Z displacement → + X displacement → −Z displacement → −X displacement to make an elliptical motion in the XZ plane. Thus, since the contact part 2a and the contact part 2b are always displaced in the opposite direction, the contact part 2a and the contact part 2b are elliptical motions of opposite phases. The contact portion 2a and the contact portion 2b perform + Z displacement during the transition from −X displacement to + X displacement. That is, the contact portion 2a and the contact portion 2b transmit the force in the + X direction while being in contact with the contact surface 1a of the driven body 1. Thereby, the driven body 1 moves relative to the vibration elastic body 2 in the + X direction. Thus, since the two contact portions 2a and 2b alternately generate driving force, a high-speed ultrasonic motor that efficiently generates driving force can be realized. Further, since the two contact portions 2a and 2b are arranged in the Y direction orthogonal to the relative movement direction, an ultrasonic motor having a small size in the X direction that is the relative movement direction can be realized.

  In FIG. 4, the rectangular wave AC voltage pattern has been described for the sake of simplicity. However, the effect of the present invention is not limited to the rectangular wave, and the same effect can be obtained with an AC voltage pattern such as a sine wave. can get. Also, the phase difference between the two AC voltage patterns has been described with an example of 90 ° for the sake of simplicity, but the effect of the present invention is not limited to 90 °, and even in the vicinity of the phase difference, etc. Similar effects can be obtained.

  FIG. 6 is a diagram for explaining the shape and dimensions of the vibration elastic body 2. In order for the vibration elastic body 2 to excite both the push-up vibration mode and the feed vibration mode, the difference between the resonance frequencies of the two vibration modes must be small. At this time, the difference between the resonance frequencies of the two vibration modes is correlated with the ratio of the length 2LX in the X direction and the length 2LY in the Y direction of the flat plate portion 2g. Therefore, the ratio of the length 2LX in the X direction and the length 2LY in the Y direction of the flat plate portion 2g needs to be within a predetermined range. In the ultrasonic motor of the present embodiment, a secondary bending vibration mode in the YZ plane and a primary torsional vibration mode in which the center in the X direction and the center in the Y direction are nodes at the same time are used for the vibration elastic body 2. At that time, unless the length 2LY in the Y direction is set to 3 to 8 times the length 2LX in the X direction, the difference between the resonance frequencies of the two vibration modes becomes too large to excite both vibrations. It becomes difficult. Therefore, in the ultrasonic motor of this embodiment, the length 2LY in the Y direction of the flat plate portion 2g is set to 3 to 8 times the length 2LX in the X direction. Thereby, by applying a predetermined AC voltage pattern to the piezoelectric element 3, both the push-up vibration mode and the feed vibration mode can be excited in the vibration elastic body 2. That is, when the length in the relative movement direction of the region where the vibration elastic body and the piezoelectric element are fixed is L1, and the length in the direction orthogonal to the relative movement direction is L2, L1 and L2 have the following relationship. L1 × 3.0 <L2 <L1 × 8.0

  In FIG. 6, since the push-up vibration mode is a secondary bending vibration mode, there are three node positions 2h, 2m, and 2n. The node position 2h is located at the center in the Y direction, and the node position 2m and the node position 2n are located approximately 1/8 inward from both ends in the Y direction. There are two abdominal positions, 2j and 2k. The antinode position 2j and antinode position 2k are approximately ３ positions inward from both ends in the Y direction. On the other hand, since the feed vibration mode is a primary torsional vibration mode, there are two node positions 2h and 2i. The node position 2h is located at the center in the Y direction, and the node position 2i is located at the center in the X direction. The contact part 2a and the protrusion part 2c are provided in the vicinity of the intersection of the antinode position 2k in the push-up vibration mode and the node position 2i in the feed vibration mode. Similarly, the contact portion 2b and the protrusion 2d are provided in the vicinity of the intersection of the antinode position 2j in the push-up vibration mode and the node position 2i in the feed vibration mode. By disposing the contact portion 2a and the contact portion 2b at such positions, the reciprocating vibration is generated in the Z direction by the push-up vibration mode, and the reciprocating vibration is performed in the X direction by the feed vibration mode. By combining these two vibration modes with a predetermined phase difference, elliptical vibration in the XZ plane is generated in the contact portion 2a and the contact portion 2b.

  In FIG. 6, it is appropriate to provide the arm portion 2e at a place where vibration is as small as possible. Therefore, the arm portion 2e is arranged on the extension line of the node position 2i in the feed vibration mode, so that the arm portion 2e is less likely to vibrate in the feed vibration mode. This makes it difficult for the vibration in the feed vibration mode to be inhibited, and reduces the propagation of vibration to the fixed portion 2f via the arm portion 2e.

  FIG. 7 is a developed perspective view of the ultrasonic motor of this embodiment. Reference numeral 1 denotes a driven body, which moves relative to the vibration elastic body 2 in the X direction by elliptical vibration excited by the contact portion 2a and the contact portion 2b of the vibration elastic body 2. Reference numeral 1b denotes a fixing hole for fixing the driven body 1 to a moving body (not shown). The driven body 1 is screwed to a moving body (not shown) through two fixing holes 1b. 2 is a vibration elastic body. The vibration elastic body 2 includes a flat plate portion 2g to which the piezoelectric element 3 is fixed, a protruding portion 2c protruding from the flat plate portion in the + Z direction, a protruding portion 2d, and contact portions formed on the upper end surfaces of the protruding portions 2c and 2d. 2a and 2b. The vibration elastic body 2 is fixed to a holding portion (not shown) with screws by fixing portions 2f provided at both ends of the flat plate portion 2g. An arm portion 2e is provided between the flat plate portion 2g and the fixed portion 2f to make it difficult for vibration generated in the flat plate portion 2g to propagate to the fixed portion 2f. Reference numeral 3 denotes a piezoelectric element fixed to the −Z surface side of the flat plate portion 2g. One non-divided electrode region 3g is formed on the surface of the piezoelectric element 3 that is in contact with the vibration elastic body 2 (+ Z side), and the electrode region 3g and the vibration elastic body 2 are electrically connected.

  FIG. 8 is an assembly diagram of the ultrasonic motor of this embodiment. 8A is a perspective view of the assembled state, FIG. 8B is a view of the assembled state viewed from the + X direction, and FIG. 8C is a view of the assembled state viewed from the + Y direction. is there. 8A, 8B, and 8C, the −Z side surface of the flat plate portion 2g of the vibration elastic body 2 and the + Z side surface of the piezoelectric element 3 are fixed. By the alternating voltage applied to the piezoelectric element 3, the vibration elastic body 2 is excited in the push-up vibration mode and the feed vibration mode, and elliptical vibration in the XZ plane is generated in the contact portion 2a and the contact portion 2b. The vibration elastic body 2 and the driven body 1 are held in a state of being pressurized in the Z direction. Therefore, the contact portion 2a and the contact portion 2b of the vibration elastic body 2 are maintained in a so-called pressure contact state in which the contact surface 1a of the driven body 1 is contacted in a pressurized state. When elliptical vibration in the XZ plane occurs in the contact part 2a and the contact part 2b in such a pressure contact state, the driven body 1 and the vibration elastic body 2 move relative to each other in the X direction. At this time, since the vibration elastic body 2 is fixed to the holding portion by the fixing portion 2f and the movement in the X direction is restricted, the driven body 1 moves in the X direction.

  In FIG. 8C, since the contact part 2a and the contact part 2b are arranged in the Y direction, the contact length in the X direction is the diameter of the contact part 2a and the contact part 2b, which is very short. Therefore, the length of the contact surface 1a of the driven body 1 in the X direction may be ensured by a length corresponding to the sum of the diameters of the contact portion 2a and the contact portion 2b and the relative movement distance of the vibration elastic body 2. . Therefore, the size of the driven body 1 in the X direction can be reduced. On the other hand, in the conventional ultrasonic motor as described in Patent Document 1 described above, the contact portions are arranged in the relative movement direction. Therefore, the contact length in the relative movement direction is not only the length obtained by adding the diameter of the two contact portions and the relative movement distance, but also the length obtained by adding the distance between the two contact portions, which is very long. End up. Therefore, it is necessary to ensure a long contact surface of the driven body, and the size of the driven body has become very large in the relative movement direction. Accordingly, the size of the ultrasonic motor has become very large in the relative movement direction.

  In the ultrasonic motor of the present embodiment, as shown in FIG. 8B, the contact portion 2a and the contact portion 2b are arranged in the Y direction, which is a direction orthogonal to the relative movement direction. As a result, as shown in FIG. 8C, the contact length in the X direction, which is the relative movement direction, can be shortened, and the size of the driven body 1 in the relative movement direction can be reduced. Accordingly, the size of the ultrasonic motor unit in the driving direction can be reduced.

[Example 2]
In the first embodiment, the arm portion 2e of the vibration elastic body 2 is provided on an extension line of the node position 2i in the feed vibration mode, thereby reducing vibration inhibition and vibration propagation to the fixed portion 2f in the feed vibration mode. It was. The second embodiment is different from the first embodiment in that the arm portion 2e is provided on the extended line of the node position 2h which is the node in both the push-up vibration mode and the feed vibration mode. In addition, the same member as Example 1 is shown with the same symbol. The description of the same parts as in the first embodiment is omitted, and only the parts different from the first embodiment will be described.

  FIG. 9 is a diagram for explaining the shape and dimensions of the vibration elastic body 2 of the second embodiment. In FIG. 9, it is appropriate to provide the arm 2e at a place where vibration is as small as possible. Therefore, the arm portion 2e is arranged on the extended line of the node position 2h, which is the node in both the push-up vibration mode and the feed vibration mode, and the arm portion 2e is capable of both vibrations in the push-up vibration mode and the feed vibration mode. It is hard to vibrate. As a result, the vibration is further prevented from being inhibited, and the propagation of the vibration to the fixed portion 2f via the arm portion 2e is reduced.

[Example 3]
In the second embodiment, the arm portion 2e is provided on the extended line of the node position 2h, which is the node in both the push-up vibration mode and the feed vibration mode, to reduce vibration inhibition and vibration propagation to the fixed portion 2f. It was. In the third embodiment, among the nodes in the push-up vibration mode, the arm portion 2e is provided on the extended line of the node position 2m and the node position 2n located at about 1/8 from both ends in the Y direction. It is different from 2. In addition, the same member as Example 1 and Example 2 is shown with the same symbol. The description of the same parts as those in the first and second embodiments is omitted, and only different parts are described.

  FIG. 10 is a diagram for explaining the shape and dimensions of the vibration elastic body 2 of the third embodiment. In FIG. 10, it is appropriate to provide the arm portion 2e at a place where vibration is as small as possible. Therefore, among the nodes in the push-up vibration mode, the arm part 2e is provided on the extension line of the node position 2m and the node position 2n located at about 1/8 from both ends in the Y direction, and the arm part 2e is pushed up and vibrated. It is difficult to vibrate depending on the mode. This makes it difficult for the vibration in the push-up vibration mode to be inhibited, and reduces the propagation of vibration to the fixed portion 2f via the arm portion 2e.

  Since the arm portion 2e of the vibration elastic body 2 of Example 2 was positioned at the center in the Y direction of the flat plate portion 2f, the projection region when viewed from the Z direction overlapped with the fixed portion 2f and the driven body 1. For this reason, when trying to form a holding portion (not shown) for fixing the fixing portion 2f, the position in the Z direction is limited in order to avoid interference with the driven body 1. However, in the third embodiment, by providing the arm portion 2f at a position about 1/8 from both ends of the flat plate portion 2f in the Y direction, the projection region when viewed from the Z direction is fixed by the fixed portion 2f and the driven body 1. Do not overlap. Therefore, there is an advantage that the degree of freedom in design when forming a holding portion (not shown) for fixing the fixing portion 2f is increased.

[Example 4]
In Examples 1 to 3, the piezoelectric element 3 is composed of a single plate piezoelectric element. In Example 4, the piezoelectric element 3 is composed of a laminated piezoelectric element in which a piezoelectric element layer 4 for exciting the push-up vibration mode and a piezoelectric element layer 5 for exciting the feed vibration mode are laminated. This is different from the first to third embodiments. In addition, the same member as Example 1 is shown with the same symbol. The description of the same parts as in the first embodiment is omitted, and only the parts different from the first embodiment will be described. FIG. 11 is a diagram for explaining two types of piezoelectric element layers of the piezoelectric element 3 of the fourth embodiment. FIG. 11A is a view of the piezoelectric element layer 4 for exciting the push-up vibration mode as seen from the −Z direction, and FIG. 11B is a view as seen from the + Z direction. FIG. 11C is a view of the piezoelectric element layer 5 for exciting the feed vibration mode viewed from the −Z direction, and FIG. 11D is a view viewed from the + Z direction.

  FIGS. 11A and 11B are diagrams showing the piezoelectric element layer 4 for exciting the push-up vibration mode. In FIG. 11A, two electrode regions 4c and 4d divided into two in the Y direction are formed on the −Z side surface of the piezoelectric element layer 4 with the center in the Y direction as a boundary line. On the other hand, in FIG. 11B, one non-divided electrode region 4g is formed on the surface of the piezoelectric element layer 4 on the + Z side. In FIG. 11A, the piezoelectric element layer 4 is subjected to polarization processing of different polarities on the −Y side and the + Y side with the center in the Y direction as a boundary line.

  Here, the electrode region 4g is electrically connected to the ground potential. Since the electrode region 4g is a surface in contact with the vibration elastic body 2, it may be conducted to the ground potential via the vibration elastic body 2. On the other hand, an alternating voltage pattern VA is applied to the electrode region 4c and the electrode region 4d. Since the piezoelectric element 4 is applied with the ground potential on the + Z side surface and the AC voltage pattern VA is applied to the −Z side surface, a potential difference occurs between the front surface and the back surface, and the piezoelectric element 4 tends to expand and contract. On the other hand, since the surface on the + Z side is fixed to the vibration elastic body 2, expansion and contraction is hindered. Due to the difference in expansion and contraction between the front surface and the back surface, out-of-plane bending occurs in the piezoelectric element layer 4. The electrode region 4c and the electrode region 4d are applied with voltages having the same potential, but have different polarization directions. Therefore, the vibration component of the push-up vibration mode which is the second bending vibration mode in the YZ plane is applied to the vibration elastic body 2. Is excited.

  On the other hand, FIGS. 11C and 11D are diagrams showing the piezoelectric element layer 5 for exciting the feed vibration mode. In FIG. 11C, on the −Z side surface of the piezoelectric element layer 5, four electrode regions 5c, 5d, which are divided into two in the XY direction, respectively, with the center in the X direction and the center in the Y direction as a boundary line. Electrode region 5e and electrode region 5f are formed. On the other hand, in FIG. 11D, one electrode region 5g that is not divided is formed on the surface of the piezoelectric element layer 5 on the + Z side.

  In FIG. 11, the piezoelectric element layer 5 is subjected to different polar polarization processing in regions adjacent to each other in the XY direction with the center in the X direction and the center in the Y direction as a boundary line. Here, the electrode region 5g is electrically connected to the ground potential. As a method for conducting the electrode region 4g and the electrode region 5g, there is a method in which through holes are provided in the piezoelectric element layer 4 and the piezoelectric element 5, and the electrode region 4g of the piezoelectric element layer 4 and the electrode region 5g of the piezoelectric element layer 5 are electrically connected. Conceivable. Further, a method of applying a conductive paste to the end face portion of the piezoelectric element 4 and conducting it can be considered. An AC voltage pattern VB is applied to the electrode region 5c, electrode region 5d, electrode region 5e, and electrode region 5f. Since the piezoelectric element layer 5 is applied with the ground potential on the + Z side surface and the AC voltage pattern VB is applied on the -Z side surface, a potential difference is generated between the front surface and the back surface, and the piezoelectric element layer 5 tends to expand and contract. Due to the difference in expansion and contraction between the front surface and the back surface, out-of-plane bending occurs in the piezoelectric element layer 4. The electrode region 5c, the electrode region 5d, the electrode region 5e, and the electrode region 5f are applied with the same potential voltage, but the polarization directions are the same in the diagonally adjacent electrode regions, and are adjacent in the X direction or the Y direction. The electrode regions differ in polarization direction. Therefore, the vibration elastic body 2 is excited with the vibration component of the feed vibration mode which is the primary torsional vibration mode.

  As in the first to third embodiments, by applying the AC voltage pattern VA and the AC voltage pattern VB whose phases are shifted by a predetermined amount, the vibration elastic body 2 is excited with the combined vibration of the push-up vibration mode and the feed vibration mode. . In Example 4, the piezoelectric element 3 is composed of a laminated piezoelectric element in which the piezoelectric element layer 4 and the piezoelectric element layer 5 are bonded together. Therefore, the piezoelectric element 4 for exciting the push-up vibration mode and the piezoelectric element 5 for exciting the feed vibration mode are separated, and an applied voltage can be applied independently. Therefore, the feature of the fourth embodiment is that the push-up vibration mode and the feed vibration mode can be controlled independently.

  As described above, in the vicinity of the intersection of the antinode position of the secondary bending vibration mode of the vibration elastic body 2 and the position of the node of the primary torsional vibration mode, the two contacts contacting the contact surface of the driven body 1 The contact parts 2a and 2b, which are parts, are provided. As a result, the contact portion 2a and the contact portion 2b alternately generate a driving force, and a high-speed ultrasonic motor that efficiently generates the driving force can be realized. In addition, since the contact portion 2a and the contact portion 2b are arranged in a direction orthogonal to the relative movement direction, an ultrasonic motor having a small size in the relative movement direction can be realized.

[Example 5]
FIG. 12 shows a cross-sectional view of a fifth embodiment relating to a lens barrel incorporating the ultrasonic motor unit (ultrasonic actuator) 100 of the present invention. In the present embodiment, the lens barrel is described as an interchangeable lens that can be exchanged for the camera body. Since the lens barrel is substantially rotationally symmetric around the optical axis, only the upper half is displayed.

  An interchangeable lens 52 is detachably attached to the camera body 51, and an image sensor 51 a is provided in the camera body 51. The mount 11 has a bayonet portion for attaching the interchangeable lens 52 to the camera body 51. The fixed cylinder 12 is in contact with the flange portion of the mount 11 and fixes the mount 11 with screws (not shown). A fixed barrel 12 is fixed with a front barrel 13 holding the fixed lens G1 and a rear barrel 14 holding the fixed lens G3. Reference numeral 15 denotes a focus lens holding frame that holds the focus lens G <b> 2, and is held by a known guide bar 16 held by the front lens barrel 13 and the rear lens barrel 14 so as to be linearly movable. A flange portion (not shown) is formed on the base plate in the ultrasonic motor unit 100 and is fixed to the rear lens barrel 14 with screws.

  When the driven portion 102 of the ultrasonic motor unit 100 is driven with the above configuration, the driving force of the ultrasonic motor unit 100 is transmitted to the focus lens holding frame 15 via the driving force transmitting portion 103. . The focus lens holding frame 15 moves linearly along the guide bar 16 described above. Thus, the lens holding frame 15 is driven by the driving force of the ultrasonic actuator of the present invention.

  As mentioned above, although the preferable Example of this invention was described, this invention is not limited to these Examples, A various deformation | transformation and change are possible within the range of the summary.

  1..Driven body (driven part), 1a..Contact surface, 2..Vibration elastic body, 2a, 2b..Contact part, 3..Piezoelectric element, 3c, 3d, 3e, 3f,. Electrode area on the surface, 3g .. Electrode area on the other surface

Claims (10)

A piezoelectric element in which an electrode region that is divided into two in each direction is formed on one surface and one electrode region is formed on the other surface;
The piezoelectric element fixed to the vibration elastic body excites vibrations of the secondary bending vibration mode and the primary torsional vibration mode with a predetermined phase shift, and the antinode position of the secondary bending vibration mode and the A vibrating elastic body having two contact portions provided at an intersection with a node position of the primary torsional vibration mode;
A driven part that has a contact surface with the two contact parts and moves relative to the vibration elastic body by the vibration;
The motor characterized by having.   The motor according to claim 1, wherein the piezoelectric elements have different polarization directions in two regions arranged in a direction orthogonal to the relative movement direction.   Among the electrode regions divided into two in the vertical and horizontal directions, the electrode regions adjacent to each other in the direction orthogonal to the relative movement direction are applied with the same phase AC voltage, and the electrode regions adjacent to the relative movement direction are out of phase. The motor according to claim 1, wherein an alternating voltage is applied.   The motor according to claim 3, wherein the one electrode region that is not divided is connected to a ground potential. When the length in the relative movement direction of the region where the vibration elastic body and the piezoelectric element are fixed is L1, and the length in the direction orthogonal to the relative movement direction is L2, L1 and L2 have the following relationship. The motor according to claim 1.
L1 × 3.0 <L2 <L1 × 8.0 The vibration elastic body propagates at least one of a vibration in the first torsional vibration mode and a vibration in the second bending vibration mode to the fixed portion for fixing the vibration elastic body. And the arm portion is provided on an extension line of at least one node position of the vibration in the primary torsional vibration mode and the vibration in the secondary bending vibration mode . The motor according to claim 1. Before Kiude unit, the motor according to claim 6, characterized in that provided on the extension of the nodal positions of the primary torsional vibration mode. Before Kiude unit, the motor according to claim 6, characterized in that provided on the extension of the nodal positions of the secondary bending vibration mode. Before Kiude unit, the motor according to claim 6, characterized in that provided on the extension of the nodal positions of the primary torsional vibration mode and the second-order bending vibration mode. A lens barrel, wherein the lens holding frame is driven by a driving force of an actuator including the motor according to any one of claims 1 to 9.