JPH03183377A - Ultrasonic wave motor - Google Patents

Abstract

PURPOSE:To facilitate machining, to eliminate bonding process and to suppress dispersion by applying first and second oblique electrodes on the outer circumferential face of a hollow cylinder while inclining by about 45 deg. with respect to the axis. CONSTITUTION:First and second oblique electrodes 22, 23, inclining by about 45 deg. with respect to the axis of a hollow cylinder 21, are applied on the outer circumferential face of the hollow piezoelectric ceramic cylinder 21 thus providing first two terminals. When the hollow cylinder 21 is subjected to polarization, it is polarized in the direction perpendicular to the direction of the first and second oblique electrodes 22, 23. Upon application of a voltage between the oblique electrodes 22, 23 under this state, contractive distortion is produced in the direction of polarization if the polarity of the voltage is same as that of the polarization voltage, whereas elongating distortion is produced in the perpendicular direction. Consequently, torsional displacement is produced in the hollow cylinder 21. By such method, machining is facilitated, bonding process is eliminated and dispersion can be suppressed.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a so-called ultrasonic motor using ultrasonic vibration of a piezoelectric vibrator used in OA equipment, etc., and in particular to a torsion-spread compound vibrator with a simple structure. Regarding type ultrasonic motor.

[Prior Art] Generally, an ultrasonic motor generates an elliptical motion by combining two vibrations in different directions, and presses a rotatably supported rotor or a mover against the portion where the elliptical motion vibration is generated. It is made up of.

FIG. 7 is a perspective view showing an example of the structure of a conventional vertical-torsional transducer type ultrasonic motor, in which a piezoelectric torsional transducer 101 and a piezoelectric longitudinal transducer 102 are joined, and metal hollow cylinders 103 and A shaft 106 is protruded from the center of one end of a vertical-torsional composite vibrator 105, which is constructed by joining 104, and a rotor 108 rotatably supported by a bearing 107 is rotated by a coil spring 109 and a nut 110. It is pressed against the end face of the composite vibrator 105.

Here, the shaft 106 is fixed at a vibration node of the longitudinal-torsional composite vibrator.

FIG. 8 is a perspective view showing an example of the structure of the torsional compound vibrator 101 of the ultrasonic motor shown in FIG.
It is constructed by joining. Each fan-shaped piezoelectric ceramic plate 112 is polarized in the direction of the chord of the fan, as shown in FIG. When a DC voltage is applied, a sliding strain parallel to the plate thickness occurs in the fan-shaped piezoelectric ceramic plate.

As shown in FIG. 8, when four (F, sector-shaped) piezoelectric ceramic plates 112 are joined in a ring shape, the sliding strain generated in each sector-shaped piezoelectric ceramic plate 112 is combined, and the ring's This results in torsional distortion in which the upper and lower surfaces are twisted.

When manufacturing the conventional piezoelectric torsional vibrator 101 shown in FIG. 8, first, as shown in FIG. A fan-shaped piezoelectric ceramic plate 112 polarized in the direction of the chord of the fan as shown in FIG. As shown, from a block 114 of piezoelectric ceramics polarized in the thickness direction shown by the arrow, a square prism 115 with the polarization direction diagonal as shown in FIG. 11(b) is cut out. (C
), four square prisms 115 are stacked and glued together so that the polarization direction forms a closed loop, as shown in FIG. 11(d).
After polishing the outer and inner peripheries into a hollow cylindrical shape as shown in
It is manufactured by cutting into a ring shape as shown in FIG. 11(e).

FIG. 12 shows an example of the structure of a conventional piezoelectric vertical vibrator 102, in which a voltage is applied to a piezoelectric ceramic ring 116 that has electrodes on both sides and is polarized in the thickness direction, causing vibration in the thickness direction (
(called longitudinal vibration).

In order to obtain a large vibration amplitude with a low applied voltage, a piezoelectric longitudinal vibrator 102' may be constructed by laminating a plurality of thin piezoelectric ceramic rings 116 as shown in FIG.

[Problems to be Solved by the Invention] Since the conventional piezoelectric torsional vibrator 101 shown in FIG. 8 is configured by bonding a plurality of piezoelectric ceramics, there are large variations in characteristics due to bonding. Also, Figures 9, 10, and 11 (a), (b), (
c) As shown in (d), the piezoelectric torsion vibrator 102
The processing required to obtain this was complex and extremely expensive. Furthermore, if you want to obtain torsional vibration and longitudinal vibration at the same time, use the piezoelectric torsional vibrator 1 shown in Figure 8.
02 and the piezoelectric longitudinal vibrator 10 shown in FIG. 12 or FIG.
2, there were also problems of variations in properties due to adhesion and high adhesion costs.

Therefore, the technical problem of the present invention is to eliminate the drawbacks of the conventional ultrasonic motor shown above, provide a piezoelectric torsional vibrator that is easy to process, does not require an adhesive process, and has little variation, and furthermore, An object of the present invention is to provide an ultrasonic motor using a piezoelectric torsion-expanding composite vibrator in which an expanding vibrator is formed in the element.

[Means for Solving the Problems] According to the present invention, the outer circumferential surface of the approximately central portion in the longitudinal direction of the piezoelectric ceramic hollow cylinder has an angle of approximately 45° with respect to the axial direction of the piezoelectric ceramic hollow cylinder over the entire circumference. applying interdigital electrodes in the direction of , forming two terminals, using the interdigital electrodes to polarize the piezoelectric ceramic hollow cylinder; using the interdigital electrodes to polarize the piezoelectric ceramic hollow cylinder; An alternating current voltage is applied between the interdigital electrodes to enable torsional vibration to be excited in the piezoelectric ceramic hollow cylinder, and the piezoelectric ceramic hollow cylinder is provided near at least one end thereof in a direction parallel to the axial direction of the piezoelectric ceramic hollow cylinder. Interdigital electrodes are formed to have two terminals, and the piezoelectric ceramic hollow cylinder is polarized near the ends using the interdigital electrodes, and an alternating current voltage is applied between the interdigital electrodes to polarize the piezoelectric ceramic hollow cylinder. An ultrasonic motor is provided, comprising: an integrated torsion-expanding compound vibrator capable of exciting a spreading vibration near an end of the ultrasonic motor; and a freely rotatable rotor press-welded to the expanding vibrator portion. It will be done.

According to the present invention, interdigital electrodes are provided on the outer peripheral surface of a substantially central portion in the longitudinal direction of the piezoelectric ceramic hollow cylinder over the entire circumference in a direction approximately 45° with respect to the axial direction of the piezoelectric ceramic hollow cylinder. Two terminals are used, the piezoelectric ceramic hollow cylinder is polarized using the interdigital electrodes, the piezoelectric ceramic hollow cylinder is polarized using the interdigital electrodes, and an alternating current voltage is applied between the interdigital electrodes. to enable torsional vibration to be excited in the piezoelectric ceramic hollow cylinder, and interdigital electrodes are formed in the vicinity of at least one end of the piezoelectric ceramic hollow cylinder in a direction parallel to the circumferential direction of the piezoelectric ceramic hollow cylinder, respectively. Two terminals are used, and the interdigital electrodes are used to perform polarization near the ends of the piezoelectric ceramic hollow cylinder, and an alternating current voltage is applied between each interdigital electrode to cause vibrations to spread to the vicinity of the ends of the piezoelectric ceramic. There is obtained an ultrasonic motor characterized by comprising an integrated torsion-expansion compound vibrator capable of excitation and a rotatable rotor press-welded to the expansion vibrator portion.

[Function] In the ultrasonic motor of the present invention, in the piezoelectric torsion-expanding compound vibrator, first, a first cylindrical tube is formed on the outer circumferential surface of the piezoelectric ceramic hollow cylinder in a direction at 45° with respect to the axial direction of the hollow cylinder. and a second diagonal electrode to form a first two terminals, and when the piezoelectric ceramic hollow cylinder is polarized using the first two terminals, the polarization direction is the same as the first and second diagonal electrodes. The direction is perpendicular to the direction of the finger electrodes. In this state, when a voltage is applied between the first and second diagonal electrodes, if the polarity of the voltage is the same as the polarity of the polarization voltage, shrinkage distortion occurs in the polarization direction.

When an elongation or contraction strain occurs in the polarization direction, a contraction or expansion strain occurs in the direction perpendicular to the polarization direction, respectively, in the opposite direction.

As a result of the above, torsional displacement occurs in the piezoelectric ceramic hollow cylinder.

In addition, in the ultrasonic motor of the present invention, in the piezoelectric torsion-spread vibrator, first and second vertical electrodes are provided on the outer peripheral surface of the piezoelectric ceramic hollow cylinder in a direction along the axis of the hollow cylinder. When the piezoelectric ceramic hollow cylinder is polarized using the second two terminals, the polarization direction is perpendicular to the direction of the finger electrodes of the interdigital electrodes, that is, the circumferential direction of the hollow cylinder. Become. In this state, when a voltage is applied to the interdigital electrodes, if the polarity of the voltage is the same as the polarity of the voltage during polarization, stretching distortion will occur in the direction of polarization, and the polarity of the voltage will be greater than the polarity of the voltage during polarization. In the opposite case,
Shrinkage distortion occurs in the direction of polarization. That is, the diameter of the hollow cylinder increases or decreases due to the longitudinal effect.

On the other hand, in the piezoelectric torsion-expansion composite vibrator of the ultrasonic motor of the present invention, first and second circumferential electrodes are provided on the outer peripheral surface of a hollow cylinder made of piezoelectric ceramic in a direction along the circumference of the hollow cylinder. A second two-terminal similar to the second two-terminal described above is used, and when the piezoelectric ceramic hollow cylinder is polarized using this second two-terminal, the polarization direction is in the direction of the electrode fingers of the interdigital electrode. In other words, the direction is perpendicular to the axis of the hollow cylinder.

In this state, when a voltage is applied to the second two terminals, if the polarity of the voltage is the same as the polarity of the voltage at the time of polarization, an elongation strain will occur in the direction of polarization, and the polarity of the voltage will change to the voltage at the time of polarization. If the polarity is opposite to that of , shrinkage distortion occurs in the direction of polarization.

As a result, the diameter of the hollow cylinder increases or decreases due to the transverse effect.

[Embodiments] Examples of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a perspective view showing an example of the structure of an ultrasonic motor according to the present invention.

In FIG. 1, the shaft 6 is passed through the hollow part of the piezoelectric torsion-spread compound vibrator 28, and fixed at the resonance node of the piezoelectric torsion-spread compound vibrator 28 inside the piezoelectric torsion-spread compound vibrator 28. do. A cup-shaped rotor 8 rotatably supported by a bearing 8 at the end of the shaft 6 is configured to be pressed against the outer circumferential surface of the end of the composite vibrator 28 through a spring 9 and a piezoelectric torsion 10. . The piezoelectric torsion-composite vibrator 28 can be fixed with a ring-shaped support frame 30 at its center, which is the position of the resonance node of torsional vibration, and this support frame 30 enables stable support.

FIGS. 2(a), (b), (c), and (d) are explanatory diagrams of the operating principle of a piezoelectric torsion-spanning compound vibrator used in an ultrasonic motor according to an embodiment of the present invention.

FIG. 2(a) is a perspective view showing interdigital electrodes formed on a piezoelectric ceramic surface.

In FIG. 2(a), a plurality of first and second finger electrodes 1 are arranged parallel to each other on one surface of a piezoelectric ceramic plate 17.
8.19 are formed, and the end portions on the same side are connected to the common electrodes 18 and 19- every other time, thereby forming interdigital electrodes.

FIGS. 2(b), (c), and (d) are cross-sectional views schematically showing interdigital electrodes formed on the surface of the piezoelectric ceramic plate of FIG. 2(a). In FIG. 2(a), a dashed arrow 1 indicates that the finger electrodes 18 and 19 in FIG. 2(a) are connected to two terminals 5 and 6.
Figures 2(c) and 2(d) show the direction of polarization when the piezoelectric ceramic plate 17 is polarized as shown in Figure 2(b). 6 shows the state of distortion that occurs when a DC voltage is applied, and the solid arrow 2 indicates the direction of the electric field.

As can be seen from Figure 2 (C), when the polarity of the voltage is opposite to the polarity of the voltage during polarization, that is, when solid arrow 2 and broken arrow 1 are in opposite directions, the contraction occurs in the direction of polarization. Distortion occurs.

FIG. 3 shows the state of distortion that occurs on the outer peripheral surface of the hollow cylinder 20 when both end faces of the hollow cylinder 20 are twisted as shown by the arrows in the figure. 45
An elongation strain occurs in the direction of the torsion arrow, and a shrinkage strain occurs in the direction perpendicular to this direction.

Therefore, interdigitated finger electrodes 18 as shown in FIG.
゜It is formed so that one direction is at an angle of 45° with respect to the axial direction of the piezoelectric ceramic hollow cylinder, and the interdigital electrodes are used as two terminals to perform polarization processing, and a DC voltage is applied to the same interdigital electrodes. Then, if the polarity of the voltage is opposite to the polarity of the voltage during polarization, it will be twisted in the opposite direction.

Furthermore, interdigital electrodes as shown in FIG. 2 are formed on the outer circumferential surface of the piezoelectric ceramic hollow cylinder 20 adjacent to the center, with the direction of the electrode fingers along the axis of the piezoelectric ceramic hollow cylinder. When polarization is performed using the electrodes as two terminals and a DC voltage is applied to the same interdigital electrode, the diameter of the hollow cylinder increases if the polarity of the voltage is the same as the polarity of the voltage during polarization, and the polarity of the voltage becomes polarized. Conversely, if the polarity of the voltage is opposite to that of the current, the diameter increases.

On the other hand, interdigital electrodes as shown in Fig. 2 are formed on the outer peripheral surface of the piezoelectric ceramic hollow cylinder, with the direction of the finger electrodes parallel to the circumferential direction of the piezoelectric ceramic hollow cylinder, and polarization is performed using the interdigital electrodes. When a DC voltage is applied to the same interdigital electrode, the length of the hollow cylinder increases when the polarity of the voltage is the same as the polarity of the voltage during polarization, and the polarity of the voltage is opposite to the polarity of the voltage during polarization. In this case, the length of the hollow cylinder 20 is reduced.

As a result, the diameter of the hollow cylinder 20 becomes smaller or larger due to the lateral effect.

FIG. 4 is a perspective view showing an example of the structure of a piezoelectric torsion-expansion composite vibrator used in an ultrasonic motor according to an embodiment of the present invention.

In FIG. 4, a plurality of first and second oblique electrodes 22 and 23 are arranged parallel to each other at an angle of 45° to the axial direction on the outer circumferential surface of the piezoelectric ceramic hollow cylinder 2 at the approximate center thereof. are formed, respectively, first and second common electrodes 2
2' and 23'. Furthermore, near one end of the piezoelectric ceramic hollow cylinder 21, a plurality of first and second vertical electrodes 24°2 are arranged parallel to the axial direction and intersecting with each other.
5 are formed, each having the same number as the third and fourth common electrodes 24-. 25-, it is electrically connected.

In FIG. 4, first and second common electrodes 22' and 2
3' is the first two terminals, and after polarization treatment is performed by applying a high DC voltage between the first two terminals, an AC voltage with a frequency equal to the resonance frequency of the torsional mode of the compound vibrator is applied. For example, the piezoelectric ceramic hollow cylinder 21 resonates so that both ends thereof are twisted.

Similarly, the third and fourth common electrodes 24-25' are used as second two terminals, and after polarization treatment is performed by applying a DC high voltage between the second two terminals, the torsional resonance If an AC voltage equal to the frequency is applied, the piezoelectric ceramic hollow cylinder 2
The ends of 1 spread and vibrate at the torsion resonance frequency due to the longitudinal effect.

The resonant frequency of the torsional vibration of the hollow cylinder 21 is determined by the length of the hollow cylinder, and the resonant frequency of the spreading vibration is determined by the average diameter of the hollow cylinder. Therefore, by appropriately selecting the average diameter, the resonant frequency of the torsional vibration can be adjusted. and the resonance frequency of the spreading vibration can be made the same.

FIG. 5 is a perspective view showing another structural example of a piezoelectric torsion-expansion composite vibrator used in an ultrasonic motor according to an embodiment of the present invention.

In FIG. 5, on the outer circumferential surface of the approximately central part of the piezoelectric ceramic hollow cylinder, at an angle of 45° with respect to the axial direction,
A plurality of first and second oblique electrodes 32 and 33 are arranged parallel to each other.
is formed in the same way as the piezoelectric torsion-expansion composite vibrator shown in FIG. Each type is common! 1ii32- and 33-
It is connected to the.

Further, near one end of the piezoelectric ceramic hollow cylinder 21', a plurality of first and second electrodes are arranged parallel to each other along the circumference.
circumferential electrodes 34, 35 are formed, and the electrodes having the same number are electrically connected by third and fourth common electrodes 34' and 35''.

In FIG. 5, the first and second common electrodes are used as the first two terminals, and after polarization treatment is performed by applying a DC high voltage between the first two terminals, the torsional mode of the compound vibrator is When an alternating current voltage with a frequency equal to the resonance frequency is applied to the second two terminals, the piezoelectric ceramic hollow cylinder 21- resonates so that both ends are twisted.

Similarly, the third and fourth common electrodes 34 and 35 are made into two second terminals, and a DC high voltage is applied between the second two terminals to perform polarization treatment. If an AC voltage equal to the resonance frequency is applied, the piezoelectric ceramic hollow cylinder 2
The 1' end expands and vibrates at the torsion resonance frequency due to the transverse effect. The resonant frequency of the torsional vibration of a hollow cylinder is determined by the length of the hollow cylinder, and the resonant frequency for the spreading motion is determined by the average diameter of the hollow cylinder, so by appropriately selecting the average diameter, the resonant frequency of the torsional vibration and the resonant frequency of the torsional vibration can be adjusted. The resonance frequency of the spreading vibration can be made the same.

Figure 6(a) is a front view showing the vibration position of the piezoelectric torsion vibrator in Figures 4 and 5, and Figures 6(b) and (c) are the piezoelectric torsion vibration positions in Figure 6(a). FIG. 2 is an explanatory diagram of a vibration state of a composite vibrator 28. FIG. In FIG. 6(b), for torsional vibration, the central part of the piezoelectric vertical composite vibrator 28 becomes a vibration node, while both ends have the maximum torsional displacement.

As shown in FIG. 6(C), even with respect to spreading vibration, the central portion becomes a node of vibration, and the amount of spreading displacement becomes maximum at both ends.

As can be seen from FIGS. 6(b) and 6(c), if the frequency of the applied voltage for the spreading vibration is the same as the torsional resonance frequency, the end of the piezoelectric torsion-spreading composite vibrator 28 will be at the torsional resonance frequency. It vibrates in the diametrical direction in synchronization with the frequency. Therefore, when the diameter of the end of the piezoelectric torsion-expansion compound vibrator 28 expands, it is twisted in one direction, and when it is contracted, it is twisted in the opposite direction. As a result, elliptical motion vibration occurs on the outer peripheral surface near the end of the piezoelectric film-torsion composite vibrator 28. If the phases of the applied voltages for either the torsional vibration or the spreading vibration are made to differ by 180 degrees from each other, the direction of the elliptic motion vibration is reversed.

[Effects of the Invention] As explained above, according to the present invention, torsional vibration and spreading vibration are used as vibration modes for configuring an ultrasonic motor, and press molding technology that is normally applied in a membrane is used to create an ultrasonic motor. By using piezoelectric ceramic hollow cylinders that can be easily manufactured and applying electrode printing, which is also a common technique, to the outer peripheral surface of these cylinders, a piezoelectric torsion oscillator and a piezoelectric spreading oscillator can be obtained as an integrated structure. Therefore, it is possible to obtain a piezoelectric film-torsion composite vibrator that is easy to manufacture and has less variation in characteristics due to bonding steps and complicated processing steps.

Further, according to the present invention, if an ultrasonic motor is constructed using a piezoelectric torsion-expansion compound vibrator, an ultrasonic motor with a simple structure and less variation in characteristics can be obtained, and the practical effects are great. .

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a structural example of an ultrasonic motor according to an embodiment of the present invention, and FIGS. 2(a), (b), (c),
(d) is an explanatory diagram of how distortion occurs when polarization and voltage are applied using interdigital electrodes; Figure 3 is an explanatory diagram of how distortion occurs when a piezoelectric ceramic hollow cylinder is twisted; FIG. 4 is a perspective view showing an example of the structure of a piezoelectric torsion-expansion composite vibrator used in an ultrasonic motor according to an embodiment of the present invention, and FIG. FIGS. 6(a), (b), and (c), which are perspective views showing other structural examples of the torsional-spreading compound vibrator, show the relative displacement amounts of torsional displacement and spreading displacement of the piezoelectric torsion-spreading compound vibrator. 7 is a perspective view showing an example of the structure of a conventional vertical-torsion type ultrasonic motor, FIG. 8 is a perspective view showing the structure of a conventional torsional oscillator, and FIGS. 9 and 10 are diagrams for explanation. An explanatory diagram of the manufacturing process of the torsional vibrator shown in Fig. 8, and Fig. 11 (a
), (b), (c), (d), and (e) are explanatory diagrams of the manufacturing process of a conventional torsional oscillator, FIG. 12 is a perspective view showing an example of the structure of a conventional longitudinal oscillator, and FIG. The figure is a perspective view showing another structural example of a conventional longitudinal vibrator. In the diagram, 6... shaft, 7... bearing, 8... rotor
9... Spring, 10... Nut, 17... Piezoelectric ceramic thin plate, 18.19... Finger electrode, 18-
．． 19-..., common electrode, 20... piezoelectric ceramic hollow cylinder, 21.21''... piezoelectric ceramic hollow cylinder, 22゜23.32.33... diagonal electrode (interdigital electrode for torsional vibrator) , 22-.23-.32-.33-
...Common electrode, 24.25...Vertical electrode (interdigital electrode for longitudinal effect spread oscillator), 24-. 25”...Circumferential electrode (cross-finger electrode for transverse effect spreading vibrator), 28...Piezoelectric torsion-spreading composite vibrator, 30...Support frame, 101
...Piezoelectric torsional vibrator, 102...Piezoelectric longitudinal vibrator, 1
03゜104...Metal hollow cylinder, 106...Axis, 1
07...Bearing, 108...Rotor 109...
Spring, 110... Nut, 112... Fan-shaped piezoelectric ceramic plate, 113, 114... Piezoelectric ceramic plate, 115... Piezoelectric ceramic plate prism,] 16
...Piezoelectric ceramic sling. Figure 2 Figure 7 Fan 8 Figure Start 9 Figure 10

Claims (2)

[Claims] 1. First and second oblique electrodes are formed on the outer peripheral surface of a substantially central portion in the longitudinal direction of the piezoelectric ceramic hollow cylinder over the entire circumference in a direction approximately 45° with respect to the axial direction of the piezoelectric ceramic hollow cylinder. the piezoelectric ceramic hollow cylinder is polarized using the first two terminals, and a first alternating current voltage is applied between the first two terminals to polarize the piezoelectric ceramic hollow cylinder. A torsional vibration can be excited, and first and second vertical electrodes are formed near at least one end of the piezoelectric ceramic hollow cylinder in a direction along the axis of the piezoelectric ceramic hollow cylinder, and a second two-terminal is formed. Polarization treatment is performed near the end of the piezoelectric ceramic hollow cylinder using the second two terminals, and a second AC voltage having the same frequency as the first AC voltage is applied between the second two terminals. The present invention is characterized by comprising an integrated torsion-spreading compound vibrator capable of exciting spreading vibration near the end of the piezoelectric ceramic, and a freely rotatable rotor pressure-welded to the spreading vibrator portion. ultrasonic motor. 2. First and second oblique electrodes are provided on the outer peripheral surface of a substantially central portion in the longitudinal direction of the piezoelectric ceramic hollow cylinder over the entire circumference in a direction approximately 45° with respect to the axial direction of the piezoelectric ceramic hollow cylinder. 1, and using the first two terminals to polarize the piezoelectric ceramic hollow cylinder,
A first AC voltage is applied between the first two terminals to enable torsional vibration to be excited in the piezoelectric ceramic hollow cylinder, and the piezoelectric ceramic hollow cylinder is placed near at least one end of the piezoelectric ceramic hollow cylinder. forming first and second circumferential electrodes in the direction along the circumference of the piezoelectric ceramic hollow cylinder to form a second two terminals, and using the second two terminals to polarize near the end of the piezoelectric ceramic hollow cylinder; An integrated torsion-spreading composite vibrator that can spread and excite vibration near the end of the piezoelectric ceramic by applying a second AC voltage having the same frequency as the first AC voltage between the second two terminals. and a freely rotatable rotor that is pressed into contact with the expansion transducer portion.