JP2008236980A - Ultrasonic motor element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic motor element that executes positioning by highly accurately moving a drive target, and an ultrasonic motor device. <P>SOLUTION: The ultrasonic motor element 10 has first/second electrodes 13a, 13b, which are provided by being divided into two in a length direction on one main face of a rectangular-flat-plate-like piezoelectric body 11, and third/fourth electrodes 13c, 13d provided by being divided into two in a width direction on the other main face. A phase of a voltage applied to the first/second electrodes 13a, 13b is shifted by 180 degrees. A phase of a voltage applied to the third/fourth electrodes 13c, 13d is shifted by 180 degrees. A phase of a voltage applied to the first/second electrodes 13a, 13b and a phase of a voltage applied to the third/fourth electrodes 13c, 13d are respectively shifted by 90 degrees. Consequently, it generates expanding/contracting secondary resonant vibration in a length direction and bending primary resonant vibration in a width direction in the piezoelectric body. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ultrasonic motor element and an ultrasonic motor apparatus using a piezoelectric element suitable for a linear motor, an XY stage, and the like.

  An ultrasonic motor element that drives a piezoelectric element in the L1B2 mode is known, and has recently been applied to a drive mechanism such as an XY stage, a linear motor, a rotary stage, and an autofocus mechanism of a camera (for example, a patent) References 1 and 2).

  FIG. 8 shows an explanatory diagram of the L1B2 mode in the piezoelectric element 90. The L1B2 mode is formed by superposition (degeneration) of the stretchable primary resonance (L1) mode in the length direction shown in the upper part of FIG. 8 and the bending secondary resonance (B2) mode in the width direction shown in the lower part of FIG. This is a vibration in which the antinode part of the vibration makes an elliptical motion.

  In the ultrasonic motor element driven in the L1B2 mode, two rows and two columns of electrode portions are formed on one main surface of a rectangular piezoelectric body, and two electrode portions positioned diagonally are connected by lead wires, A ground (earth) electrode is provided on the other main surface, and a sliding member is provided on the side surface of the piezoelectric body so as to come into contact with the drive symmetrical object. A voltage whose phase is shifted by 90 degrees is applied to the two sets of electrode portions. Apply and drive.

  In such an ultrasonic motor element, the ultrasonic motor element is held and the sliding member is driven in order to move the driving object using a frictional force acting between the sliding member and the driving object. A pressurizing mechanism that presses the object with a certain force is required.

  However, in the case of an ultrasonic motor element using the L1B2 mode, since there is only a vibration node in the center in the length direction of the ultrasonic motor element in the L1 mode, it is difficult to hold the ultrasonic motor element. In Document 1, the sliding member is pressed against the driving object after the widthwise side surface of the ultrasonic motor element is held by a spring.

However, holding the side surface of the ultrasonic motor element in the width direction using a spring means that the ultrasonic motor element moves somewhat in the width direction. What is the width direction of the ultrasonic motor element? Since it is also the direction in which the force that moves the drive object acts, when the ultrasonic motor moves in the width direction, the contact point between the sliding member and the drive object is shifted, and the drive object is moved and positioned with high accuracy. Can not be.
JP-A-7-184382 (FIG. 1, paragraphs [0029] to [0031], etc.) Japanese Patent Laying-Open No. 2006-187112 (FIG. 3, [0028] to [0034], etc.)

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an ultrasonic motor element and an ultrasonic motor device that can move and position a driving object with high accuracy.

  An ultrasonic motor element according to the present invention has a rectangular shape, and includes a piezoelectric element that generates an elastic secondary resonance vibration in a length direction and a bending primary resonance vibration in a width direction. Here, it is preferable that the piezoelectric element has a shape in which the natural secondary resonance frequency of the stretching vibration in the length direction coincides with the natural primary resonance frequency of the bending vibration in the width direction.

  A first ultrasonic motor device according to the present invention includes a piezoelectric body having a rectangular shape, a sliding member provided at the center of a side surface of the piezoelectric body, and two main surfaces of the piezoelectric body in the length direction. The first electrode and the second electrode provided separately, the third electrode and the fourth electrode provided in the width direction on the other main surface of the piezoelectric body, and the first and second electrodes And a power supply unit that applies a driving voltage that is 90 degrees out of phase to each of the third and fourth electrodes, and the driving voltage that the power supply unit applies to the first and second electrodes is 180 degrees in phase. The drive voltages applied to the third and fourth electrodes are shifted in phase by 180 degrees, so that the piezoelectric body has expansion / contraction secondary resonance vibration in the length direction and the width direction in the piezoelectric body. Bending primary resonance vibration is generated.

  The second ultrasonic motor device according to the present invention has a rectangular shape, and is divided into two in the length direction, the first electrode and the second electrode, the first piezoelectric body, the common electrode, the second piezoelectric body, and the width. A piezoelectric element portion formed by laminating a third electrode and a fourth electrode divided in two in this direction, a sliding member provided at the center of the side surface of the piezoelectric element portion, the first and second electrodes, A power supply unit that applies a driving voltage that is 90 degrees out of phase to each of the third and fourth electrodes, and the driving voltage that the power supply unit applies to the first and second electrodes is 180 degrees out of phase. In addition, the drive voltages applied to the third and fourth electrodes are 180 degrees out of phase, so that the piezoelectric element portion has expansion / contraction secondary resonance vibration in its length direction and its width direction. Bending primary resonance vibration is generated.

  A third ultrasonic motor device according to the present invention includes a piezoelectric body having a rectangular shape, a sliding member provided at the center of a side surface of the piezoelectric body, and two rows and two columns on one main surface of the piezoelectric body. Comprising four drive electrodes provided, a common electrode provided on the entire other main surface of the piezoelectric body, and a power supply unit for applying a drive voltage between the drive electrode and the common electrode, The four drive regions are divided into two sets of drive units composed of two drive regions located diagonally, and the power supply unit has a phase applied to each of two drive electrodes belonging to one of the two sets of drive units. By applying a voltage that generates a stretching vibration that is shifted by 180 degrees and not applying a voltage to the two drive regions belonging to the other, the piezoelectric body has a stretching secondary resonance vibration in the length direction and a width direction in the piezoelectric body. This is characterized in that a bending primary resonance vibration of is generated.

  According to the ultrasonic motor element and the ultrasonic motor device of the present invention, the positional fluctuation that adversely affects the control of the ultrasonic motor element, that is, the positional fluctuation that occurs in the ultrasonic motor element itself by driving the ultrasonic motor element. Since it can suppress by hold | maintaining an ultrasonic motor element firmly, a drive target can be moved and positioned with high precision.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows the configuration of an ultrasonic motor device. This ultrasonic motor device moves the slider 60 in the X direction by driving the ultrasonic motor element 10, and is attached to the guide 62 so as to be slidable in the X direction. A slider 60, a bearing 64 that supports the slider 60 against the pressure from the ultrasonic motor element 10, the ultrasonic motor element 10, a head 12 that is attached to the ultrasonic motor element 10 and is in sliding contact with the slider 60, A holding member 14 that holds the sonic motor element 10 and a pressing mechanism 16 that applies a force to the holding member 14 so as to press the head 12 against the slider 60 are provided.

  As shown in FIG. 1, three-dimensional orthogonal coordinates are defined with the length direction of the ultrasonic motor element 10 as the X direction, the width direction as the Y direction, and the thickness direction as the Z direction.

  A wear-resistant material (for example, an alloy material such as stainless steel or a ceramic material such as silicon carbide) is preferably used as the head 12 and is attached to the side surface of the ultrasonic motor element 10 with an epoxy resin or the like. The holding member 14 holds the end surface of the ultrasonic motor element 10 in the length direction, and the pressing mechanism 16 presses the holding member 14 toward the slider 60 without causing the holding member 14 to substantially swing in the X direction. ing.

  The structure of the ultrasonic motor element 10 viewed from the −Y direction side is shown in FIG. 2A (side view), the structure seen from the −X side is shown in FIG. 2B (first end view), and the structure seen from the + X side is shown. 2C (second end view) is shown respectively. 2B and 2C, the head 12 is not shown.

  The ultrasonic motor element 10 has a structure in which rectangular plate-shaped piezoelectric bodies made of a piezoelectric material and thin-film electrodes made of a conductive material are alternately stacked. For the piezoelectric material, piezoelectric ceramics such as lead zirconate titanate are preferably used. The conductive material is appropriately selected according to the manufacturing method of the ultrasonic motor. For example, when a piezoelectric body made of piezoelectric ceramics and an electrode are formed by simultaneous firing, a silver / palladium electrode is preferably used. It is done.

  The electrode structure of the ultrasonic motor element 10 is shown in FIG. 2D. Here, the ultrasonic motor element 10 is disassembled into each layer, and the piezoelectric body 11 and the electrodes located thereon are shown superimposed, and the electrode portions are filled with dots to clearly separate them. (Hereafter, the same applies to FIGS. 6 and 7B).

  In the ultrasonic motor element 10, the piezoelectric body 11 includes a first electrode layer having a first internal electrode 13a and a second internal electrode 13b, and a second electrode layer having a third internal electrode 13c and a fourth internal electrode 13d. The sandwiched structure has a structure that is repeatedly formed in the stacking direction.

  The first internal electrode 13a and the second internal electrode 13b constituting the first electrode layer are divided into two in the length direction of the piezoelectric body 11, and each of the first internal electrode 13a and the second internal electrode 13b is one of them. The portion is exposed to the side surface of the ultrasonic motor element 10 (the side surface opposite to the side surface on which the head 12 is provided). The first external electrode 15a for connecting the exposed portion of the first internal electrode 13a and the second external electrode 15b for connecting the exposed portion of the second internal electrode 13b are respectively provided on the side surfaces of the ultrasonic motor element 10. Is provided.

  The third internal electrode 13c and the fourth internal electrode 13d constituting the second electrode layer are divided into two in the width direction of the piezoelectric body 11, and each of the third internal electrode 13c and the fourth internal electrode 13d is a part thereof. Has a shape exposed on the end face of the ultrasonic motor element 10. Then, the third external electrode 15c for connecting the exposed portion of the third internal electrode 13c is connected to one end face of the ultrasonic motor element 10 and the fourth external electrode 15d for connecting the exposed portion of the fourth internal electrode 13d. Are provided on the other end face of the ultrasonic motor element 10, respectively.

  The first and second external electrodes 15a and 15b are connected to the first power source 18a, and the third and fourth external electrodes 15c and 15d are connected to the second power source 18b. As will be described later, the first power supply 18a applies a drive voltage whose phase is shifted by 180 degrees to the first and second internal electrodes 13a and 13b through the first and second external electrodes 15a and 15b, respectively. Driving voltages whose phases are shifted by 180 degrees are applied to the third and fourth internal electrodes 13c and 13d through the third and fourth external electrodes 15c and 15d, respectively, and the voltage output from the first power supply 18a and the second power supply 18b are applied. The output voltage is 90 degrees out of phase.

  The piezoelectric body 11 is polarized using the first and second internal electrodes 13a and 13b as a high potential and the third and fourth internal electrodes 13c and 13d as ground electrodes.

  The first and second external electrodes 15a and 15b are not shown in the piezoelectric body 11 showing the third and fourth internal electrodes 13c and 13d, and the third and fourth external electrodes 15c and 15d are The illustration of the piezoelectric body 11 showing the first and second internal electrodes 13a and 13b is omitted. Also, the third external electrode 15c and the fourth external electrode 15d are provided on different end faces, but the shapes of the third internal electrode 13c and the fourth internal electrode 13d are set so that they are formed on the same end face. May be. Further, in the ultrasonic motor element 10, each of the piezoelectric bodies 11 in the uppermost layer and the lowermost layer in the stacking direction (Z direction) is a piezoelectrically inactive layer and is electrode-protecting as will be apparent from the drive mode described later. It is for facilitating the mounting to the holding member 14 and is not necessarily required.

  Subsequently, a driving method and a driving form of the ultrasonic motor element 10 will be described. FIG. 3 is a schematic diagram showing a drive region of the ultrasonic motor element 10. The drive area of the ultrasonic motor element 10 has four areas α, β, γ, and δ so that the main surface of the ultrasonic motor element 10 that can be seen from the Z direction has two rows and two columns in the length direction and the width direction. Divided into two.

  The region α is a region where the first internal electrode 13a and the third internal electrode 13c overlap in the Z direction, the region β is a region where the second internal electrode 13b and the third internal electrode 13c overlap in the Z direction, and the region γ Is a region where the second internal electrode 13b and the fourth internal electrode 13d overlap in the Z direction, and a region δ is a region where the first internal electrode 13a and the fourth internal electrode 13d overlap in the Z direction.

  FIG. 4A shows voltage waveforms applied to the first to fourth external electrodes 15a to 15d, that is, voltage waveforms applied to the first to fourth internal electrodes 13a to 13d. A sin wave (cos wave) is usually used for this voltage, and the period is T.

The voltage V _13a applied to the first internal electrode 13a and the voltage V _13b applied to the second internal electrode _13b are out of phase by 180 degrees. Voltage _{V 13d} applied to the voltage _{V 13c} and the fourth internal electrode 13d applied to the third internal electrode 13c are 180 degrees out of phase. The voltage V _13a applied to the first internal electrode 13a is 90 degrees out of phase with the voltage V _13c applied to the third internal electrode 13c, and the voltage V _13b applied to the second internal electrode _13b is the fourth internal electrode. The voltage V _13d applied to _13d is 90 degrees out of phase.

After all, the voltage V _13a applied to the first internal electrode 13a is 90 degrees out of phase with the voltage V _13d applied to the fourth internal electrode 13d, and the voltage V _13b applied to the second internal electrode _13b is the third voltage V _13b . The voltage V _13c applied to the internal electrode 13c is also 90 degrees out of phase.

FIG. 4B shows voltage waveforms applied to the portions belonging to the regions α, β, γ, and δ in the piezoelectric body 11 by applying such a voltage. As described above, since the region α is a region where the first internal electrode 13a and the third internal electrode 13c overlap in the Z direction, the difference, “V _13a −V _13c ”, is the actual applied voltage. Similarly, the applied voltage in the region β is “V _13b -V _13c ”, in the region γ is “V _13b -V _13d ”, and in the region δ is “V _13a -V _13d ”. Note that the vertical axes (voltage axes) in FIGS. 4A and 4B are not the same scale.

  FIG. 5 schematically shows a deformation (vibration) form of the ultrasonic motor element 10 by the applied voltage shown in FIG. 4B, and the mounting position of the head 12 is indicated by a black dot P.

  At time T / 4, the forward voltage is applied to the portions belonging to the regions α and δ in the piezoelectric body 11 so that the regions α and δ expand, but conversely, the portions belonging to the regions β and γ in the piezoelectric body 11 are expanded. Since a reverse voltage is applied, the regions β and γ contract. Therefore, the position P of the head 12 is shifted to the + X side from the center in the length direction of the ultrasonic motor element 10. Thus, although the length hardly changes in the ultrasonic motor element 10, expansion / contraction displacement occurs in the length direction so that the center is shifted.

  At time T / 2, forward voltage is applied to the portions belonging to the regions γ and δ in the piezoelectric body 11 so that the regions γ and δ expand, but conversely, the portions belonging to the regions α and β in the piezoelectric body 11 Since reverse voltage is applied, the regions α and β contract. Therefore, since the bending displacement in the width direction is generated in the ultrasonic motor element 10, the position P of the head 12 moves to a position shifted to the + Y side in the central portion in the length direction.

  At the time 3T / 4, the forward voltage is applied to the portions belonging to the regions β and γ in the piezoelectric body 11 so that the regions β and γ expand, but conversely, the portions belonging to the regions α and δ in the piezoelectric body 11 Since reverse voltage is applied, the regions α and δ contract. Therefore, although the length of the ultrasonic motor element 10 hardly changes, an expansion / contraction displacement occurs in the length direction so that the center of the ultrasonic motor element 10 deviates. Therefore, the position P of the head 12 is substantially displaced in the Y direction. It becomes zero, and moves to a position shifted from the center in the length direction of the ultrasonic motor element 10 to the −X side.

  At time T, the forward voltage is applied to the portions belonging to the regions α and β in the piezoelectric body 11 and the regions α and β expand. On the other hand, the reverse voltage is applied to the portions belonging to the regions γ and δ in the piezoelectric body 11. Therefore, the regions γ and δ contract. Therefore, the ultrasonic motor element 10 has a bending displacement in the width direction in the ultrasonic motor element 10 in the direction opposite to that at T / 2. Therefore, the position P of the head 12 is − at the center in the length direction. Move to the position shifted to the Y side. At time 5T / 4, the state returns to the state of T / 4 again.

  In this way, the ultrasonic motor element 10 generates the expansion / contraction secondary resonance vibration (L2 mode) in the length direction and the bending primary resonance vibration (B1 mode) in the width direction, whereby the head 12 rotates counterclockwise. By drawing an elliptical trajectory, the slider can be moved to the −X side by using a frictional force acting between the head 12 and the slider 60. For example, if the phase of the voltage applied to the third and fourth internal electrodes 13c and 13d is reversed without changing the voltage applied to the first and second internal electrodes 13a and 13b, the slider 60 is moved to the + X side. Can be moved to.

  As apparent from FIG. 5, the length does not substantially change when the ultrasonic motor element 10 vibrates in the L2 mode, and the end face (end in the length direction) remains vibrated in the B1 mode. ) Is fixed, there is no hindrance to the movement of the central portion of the ultrasonic motor element 10. Even if the end surface of the ultrasonic motor element 10 is fixed and held by the holding member 14, the ultrasonic motor element 10 And can vibrate in the L2B1 mode. Thus, since the ultrasonic motor element 10 is held without being shaken in the X direction, the sliding position with respect to the slider 60 becomes constant, so that the moving speed control and positioning control of the slider 60 can be kept high.

  As is apparent from the above description, in the ultrasonic motor element 10, the first electrode layer / piezoelectric body 11 / third internal electrode 13c and the fourth internal electrode 13d having the first internal electrode 13a and the second internal electrode 13b. A unit composed of the second electrode layer having the L2B1 mode vibration is a minimum unit. That is, even with such a single plate structure, vibration in the L2B1 mode can be generated, and the ultrasonic motor element does not necessarily have a laminated structure.

  The ultrasonic motor element 10 preferably has a shape in which the natural secondary resonance frequency of the L2 mode vibration and the natural primary resonance frequency of the B1 mode vibration coincide with each other. For example, the length is 30 mm × width 22 mm × thickness 3 mm.

  Next, a modification of the above-described ultrasonic motor element 10 will be described with reference to FIG. FIG. 6 is drawn in the same form as FIG. 2D described above. That is, in the ultrasonic motor element constructed by the components shown in FIG. 6, the first electrode layer / first piezoelectric body 11a / common electrode 13e / second piezoelectric element having the first internal electrode 13a and the second internal electrode 13b. The body 11b / the second electrode layer having the third internal electrode 13c and the fourth internal electrode 13d serves as a unit that generates the resonance vibration of the L2B1 mode. Although only one unit is illustrated in FIG. 6, a structure in which a plurality of units are stacked may be used.

  In the ultrasonic motor element 10, the first electrode layer and the second electrode layer are alternately arranged at the position where the electrode layer is interposed. Here, however, the common electrode 13e which is a full surface electrode and connected to the ground is the first electrode layer. A laminated structure is formed so as to be positioned between the first electrode layer and the second electrode layer.

  Therefore, the first piezoelectric body 11a sandwiched between the first electrode layer and the common electrode 13e becomes a portion that generates resonance vibration in the L2 mode, and the second piezoelectric body 11b sandwiched between the second electrode layer and the common electrode 13e. Is a portion that generates resonance vibration in the B1 mode. As described above, the ultrasonic motor element 10 described above is different in that the L2 mode vibration unit and the B1 mode vibration unit are separated. The first piezoelectric body 11a and the second piezoelectric body 11b are distinguished for convenience of explanation, and both are the parts made of the piezoelectric material.

  7A shows a schematic side view of another ultrasonic motor element 20, FIG. 7B shows the electrode structure of the ultrasonic motor element 20 in the same manner as FIG. 2D, and FIG. 7C shows the drive voltage waveform of the ultrasonic motor element 20. Show.

  The ultrasonic motor element 20 includes a piezoelectric layer 21 (same as the piezoelectric body 11) divided into two rows and two columns in the length direction and the width direction, and four internal electrodes 23a to 23d, and a ground serving as an entire surface electrode. A unit that is sandwiched between the electrodes 23e is the minimum unit that generates vibration in the L2B1 mode.

  The internal electrode 23a has a shape exposed on the side surface, and the internal electrodes 23a are connected to each other by the external electrode 24a. The internal electrode 23b also has a shape exposed on the side surface, and the internal electrodes 23b are connected to each other by the external electrode 24b. The internal electrode 23c has a shape exposed at the end face, and the internal electrodes 23c are connected to each other by the external electrode 24c. The internal electrode 23d is also exposed at the end face, and the internal electrodes 23d are connected to each other by the external electrode 24d. The ground electrode 23e has a shape exposed on the side surface, and the ground electrodes 23e are connected to each other by the external electrode 24e.

  In the state shown in FIG. 7A, the ground electrode 23e is connected to the ground (earth), and a drive voltage is applied from the power source 26 to the internal electrodes 23b and 23d via the external electrodes 24b and 24d by the switch 28. The drive voltage is the voltage applied to the portions of the internal electrodes 23b, 23d and the ground electrode 23e as the entire surface electrode in the piezoelectric layer 21 as it is. In the ultrasonic motor element 20, the drive electrodes 23 b and 23 d positioned diagonally serve as one set of drive units, and the drive electrodes 23 a and 23 c serve as another set of drive units.

  In driving the ultrasonic motor element 20, as shown in FIG. 7C, the phase of the drive voltage is shifted by 180 degrees. As is apparent from the comparison between FIG. 7C and FIG. 4B, the voltage applied to the region β and the region δ shown in FIG. 4B is 180 degrees out of phase, and this voltage pattern is the drive voltage shown in FIG. 7C. Match the pattern. For this reason, even if no voltage is applied to the internal electrodes 23a and 23c, the vibration in the two regions located diagonally occurs, so that the vibration of the L2B1 mode is excited as the resonance vibration of the entire ultrasonic motor element 20. Is done.

  When the switch 28 is switched, as shown in FIG. 7C, the drive voltage is applied to the internal electrodes 23a and 23c via the external electrodes 24a and 24c. The switch 28 is operated when the traveling direction of the slider 60 is reversed.

  Furthermore, if the same drive voltage as the voltage pattern applied to the regions α to δ shown in FIG. 4B is applied to the internal electrodes 23a to 23d, a larger L2B1 mode vibration can be excited.

  As mentioned above, although embodiment of this invention was described, it cannot be overemphasized that this invention is not limited to such a form. For example, although several types of forms have been described as the internal electrode structure, they are not limited to these, and as long as vibration in the L2B1 mode can be generated, there is no restriction on the output structure of the drive voltage by the electrode structure and the power source. .

  For example, the form in which the slider 60 that moves linearly is described has been described. However, the object to be driven is not limited to this, and for example, the ultrasonic motor element 10 and the like are rotatably held by the head 12. The disk can be rotated by driving against the outer peripheral surface of the disk.

  The ultrasonic motor element according to the present invention can be manufactured using a conventionally known method for manufacturing a piezoelectric element. For example, an ultrasonic motor element composed of a single plate of piezoelectric ceramics is printed on a predetermined shape of piezoelectric ceramics (sintered body) using silver paste or the like, baked, polarized, and if necessary It can be manufactured by attaching a lead wire or the like. The laminated structure is preferably a laminate using an integrated sintering method in which a green sheet is formed by forming a ceramic powder into a sheet, an electrode pattern is printed on the sheet, and lamination, thermocompression bonding, degreasing, and firing are performed. Then, the external electrode can be formed by applying and baking a silver paste and polarizing it.

The top view which shows schematic structure of an ultrasonic motor apparatus. The side view of an ultrasonic motor element. The 1st end elevation of an ultrasonic motor element. The 2nd end elevation of an ultrasonic motor element. The figure which shows the electrode structure of an ultrasonic motor element. The schematic diagram which shows the drive area | region of an ultrasonic motor element. The figure which shows the drive voltage waveform of an ultrasonic motor element. The figure which shows the voltage waveform applied to each drive area | region of an ultrasonic motor element. The figure which shows the vibration displacement of the L1B2 mode which arises in an ultrasonic motor element. The figure which shows the component of another ultrasonic motor element. The side view which shows the structure of another ultrasonic motor element. The figure which shows the electrode structure of the ultrasonic motor element of FIG. 7A. The figure which shows the drive voltage waveform of the ultrasonic motor element of FIG. 7A. Explanatory drawing of L1B2 resonance mode.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Ultrasonic motor element, 11 * 11a * 11b ... Piezoelectric layer, 12 ... Head, 13a ... 1st internal electrode, 13b ... 2nd internal electrode, 13c ... 3rd internal electrode, 13d ... 4th internal electrode, 13e ... Common electrode, 14 ... Holding member, 15a ... First external electrode, 15b ... Second external electrode, 15c ... Third external electrode, 15d ... Fourth external electrode, 16 ... Pressing mechanism, 18a ... First power supply, 18b ... 2nd power supply, 23a-23d ... internal electrode, 23e ... ground electrode, 24a-24e ... external electrode, 26 ... power supply, 28 ... switch, 60 ... slider, 62 ... guide, 64 ... bearing, 90 ... piezoelectric element.

Claims (8)

  An ultrasonic motor element having a rectangular shape and having a piezoelectric element that generates a stretching secondary resonance vibration in its length direction and a bending primary resonance vibration in its width direction.   The piezoelectric element has a shape in which a natural secondary resonance frequency of stretching vibration in a length direction thereof matches a natural primary resonance frequency of bending vibration in a width direction thereof. Ultrasonic motor element.   The piezoelectric element includes a first electrode and a second electrode that are divided into two in the length direction on one main surface, and a third electrode that is divided into two in the width direction on the other main surface, and The ultrasonic motor element according to claim 1, further comprising a fourth electrode.   The piezoelectric element includes a first electrode and a second electrode divided into two in the length direction, a first piezoelectric body, a common electrode, a second piezoelectric body, and a third electrode and a fourth electrode divided into two in the width direction. The ultrasonic motor element according to claim 1, wherein the ultrasonic motor element has a laminated structure.   The piezoelectric element has four drive electrodes provided in two rows and two columns on one main surface in the length direction and the width direction, and a full-surface electrode provided on the other main surface. The ultrasonic motor element according to claim 1, wherein: A piezoelectric body having a rectangular shape, a sliding member provided at the center of the side surface of the piezoelectric body, and a first electrode and a second electrode provided on one main surface of the piezoelectric body by being divided into two in the length direction And the third and fourth electrodes provided on the other main surface of the piezoelectric body in the width direction, and the first, second, and third and fourth electrodes have a phase of 90 respectively. A power supply unit that applies a drive voltage that is shifted in degree,
The driving voltages applied to the first and second electrodes by the power supply unit are 180 degrees out of phase, and the driving voltages applied to the third and fourth electrodes are 180 degrees out of phase. The ultrasonic motor apparatus according to claim 1, wherein the piezoelectric body generates elastic secondary resonance vibration in the length direction and bending primary resonance vibration in the width direction. A first electrode and a second electrode having a rectangular shape divided into two in the length direction, a first piezoelectric body, a common electrode, a second piezoelectric body, and a third electrode and a fourth electrode divided into two in the width direction Are laminated in this order, a sliding member provided at the center of the side surface of the piezoelectric element portion, and the phases of the first, second electrode, and third and fourth electrodes are 90 degrees. A power supply unit that applies a shifted drive voltage;
The driving voltages applied to the first and second electrodes by the power supply unit are 180 degrees out of phase, and the driving voltages applied to the third and fourth electrodes are 180 degrees out of phase. The ultrasonic motor device according to claim 1, wherein the piezoelectric element portion generates expansion / contraction secondary resonance vibration in the length direction and bending primary resonance vibration in the width direction. A piezoelectric body having a rectangular shape, a sliding member provided in the center of the side surface of the piezoelectric body, four drive electrodes provided in two rows and two columns on one main surface of the piezoelectric body, and the piezoelectric body A common electrode provided over the other main surface, and a power supply unit that applies a drive voltage between the drive electrode and the common electrode,
The four drive regions are divided into two sets of drive units composed of two drive regions located diagonally,
The power supply unit applies a voltage that causes stretching vibrations that are 180 degrees out of phase to the two drive electrodes belonging to one of the two sets of drive units, and does not apply a voltage to the two drive regions belonging to the other. The ultrasonic motor apparatus according to claim 1, wherein the piezoelectric body generates elastic secondary resonance vibration in the length direction and bending primary resonance vibration in the width direction.

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