JP2980541B2 - Micro motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a micromotor, and more particularly, to a piezoelectric motor.

[0002]

BACKGROUND OF THE INVENTION The use of resonant piezoceramics to provide linear and rotational motion is known. A great advantage of such a system is the ability to achieve very good movements without using moving mechanical parts. Generally, such systems are limited to a motion accuracy of 1 micrometer for open loop operation and 50 nanometers for closed loop operation. When the weight of the plate to be moved is 0.5 kg, the speed is limited to 5-10 mm / sec. Under these circumstances, the force applied to the plate in the direction of movement is limited to about 5N. Achieving better solutions for such motors, i.e. faster speeds and greater driving power, is beneficial in many situations. This improved solution would be particularly beneficial if the ability to move at relatively high speeds was retained.

[0003]

SUMMARY OF THE INVENTION
Disclosed is a piezoelectric motor consisting of a flat rectangular piezoelectric plate having one electrode covering the entire surface of one large surface (back surface) of the plate and four electrodes covering the front quadrant. The electrode on the back is grounded, and the diagonal electrodes are electrically connected. Two ceramic pads are attached to one of the two longitudinal sides of the plate, and these pads are pressed against the driven object by a spring mechanism that presses the other longitudinal side.

When an AC voltage is applied to one pair of connected electrodes, the object moves to one side, and when an AC voltage is applied to the other pair of voltages, the object moves to the other side. The transversal direction has adjacent resonance frequencies (for different mode commands).

It is an object of the present invention to provide a micromotor having higher speed, higher driving force and smaller minimum step size than conventional micromotors.

[0006]

A first feature of the present invention is as follows.
It comprises a piezoelectric plate composed of a thin rectangular ceramic having at least one electrode on one large surface and a plurality of electrodes on the other large surface. Preferably, a single spacer of hard material is mounted in the center of the short side of the piezoelectric plate and pressed against the object. When at least some of the electrodes are energized, as described below,
Movement of either the piezoelectric plate or the object occurs along the direction of the sides of the rectangular piezoelectric plate.

In the first embodiment of the present invention, the size of the large rectangular surface, that is, the length in the x-axis direction and the y-axis direction is a predetermined selected length. Is preferably selected to have a predetermined resonance frequency in x and y (directions contained in the large rectangular surface of the piezoelectric plate), although in different modes. Preferably,
The resonance has overlapping characteristic curves.

[0008] Excitation of the piezoelectric plate is achieved by applying an AC voltage at a frequency at which both modes are excited for a selected one of the plurality of electrodes. In this embodiment, the resonant excitation is applied for at least some minimum period when a small displacement is required, and for a longer period when a larger displacement is required.

In a second embodiment of the invention, the excitation is a non-resonant asymmetric pulse voltage to some of the plurality of electrodes. The inventor has found that very small movements are achieved when such pulses are used, for example rectangular pulses having a relatively high time higher than the low time. Such excitation is particularly useful where it is desired that no residual voltage remains on the electrodes after exercise.

In a third embodiment of the invention, a resonant AC excitation used when driving an object in relatively large steps and a pulse excitation used when driving an object in small steps are used. Can be switched between.

Many electrode configurations are possible with the present invention. In one embodiment, the plurality of electrodes comprises two rectangular electrodes, each covering half of one rectangular surface of the piezoelectric plate and extending along the length of the large rectangular surface of the ceramic.

A second preferred electrode shape is to divide the large surface of the piezoelectric plate into four parts vertically and horizontally,
That is, an electrode is provided to the quadrant. If the different excitation modes (AC and pulse) and the excitation shape result in a larger or smaller minimum step size for the movement caused by the motor, one or two of these electrodes,
Or three are excited.

Another feature of the present invention involves the use of a plurality of stacked piezoelectric plates having the same resonance frequency,
It is preferably formed of different piezoelectric materials, one of which is substantially softer than the other. Ceramics with different hardness are driven out of phase signal at the same frequency. In such a system, a harder material provides a higher driving force during the portion of the cycle that drives the object, and a softer material provides a longer contact time but less force. This combination allows for a high start drive to overcome inertia and static friction forces, and with smooth motion during movement.

A preferred embodiment of the present invention involves the use of a mode suppression device that increases the efficiency of the micromotor by suppressing resonance modes other than the desired mode.

According to still another feature of the present invention, one end of the arm is attached to the short side of the piezoelectric plate opposite to the side where the spacer bearing is provided. A spacer biased against the object is attached to the second end of the arm. In operation, the two spacers excite similarly, moving away from the phase motion at the driven object, increasing the output of the micromotor, and applying the motion and force at both ends of the piezoelectric plate to attach the two spacers. Smooth movement of the energized object is provided.

Another feature of the present invention involves the use of a resilient element applied to a point on the long side of the piezoelectric plate where the amplitude of motion perpendicular to the plane of the long side is substantially zero. Such elements are used to impart symmetrical motion to the object in both directions parallel to the short side of the piezoelectric plate.

According to yet another aspect of the present invention, a piezoelectric micromotor according to the present invention is utilized for moving an optical or magnetic read / write head of a disk drive.

Thus, in a preferred embodiment of the present invention, the micromotor for moving the object comprises long and short sides, first and second surfaces, electrodes mounted on the first and second surfaces,
At least one rectangular piezoelectric plate having a ceramic spacer mounted on a first side, preferably the short side, preferably at the center thereof, and pressed against an object, and preferably on a second side opposite the first side. It consists of an elastic force source for applying a force to the center and pressing the ceramic spacer against the object, and a power source for exciting at least some of the electrodes.

In a preferred embodiment of the invention, the voltage source energizes at least some of the electrodes with a symmetric, unipolar pulsed excitation voltage.

Preferably, the voltage source is operative to selectively apply several electrodes, either with symmetric, unipolar pulses or with AC excitation.

In a preferred embodiment of the invention, the electrodes comprise a plurality of electrodes, preferably on each quadrant of the first surface of the piezoelectric plate, and at least one electrode on the second surface.

In a preferred embodiment of the present invention, the electrodes in the quadrant along one long side of the first surface of the plate are applied with a unipolar symmetric pulse voltage having a first polarity, and The electrodes located at the four divisions along the other long side of the surface are applied with a unipolar symmetric pulse voltage having the opposite polarity.

Alternatively, the electrodes of each quadrant proximate to the ceramic spacer may be applied with a unipolar symmetric pulse voltage of opposite polarity or the electrodes of each quadrant remote from the ceramic spacer may be opposite. Is applied.

In a preferred embodiment of the present invention, the first set of electrodes of the diagonally located quadrant is applied with a unipolar symmetric pulse voltage having a predetermined polarity, preferably on a diagonal. The second set of electrodes of the quadrant is applied with a unipolar symmetric pulse voltage having a polarity opposite to the predetermined polarity.

In a preferred embodiment of the invention, the micromotor comprises a plurality of said piezoelectric plates, the ceramic spacer of each plate being elastically pressed against the object. Preferably, at least one of the plurality of plates is formed of a relatively harder piezoelectric material, and at least one of the plurality of plates is formed of a relatively softer piezoelectric material. In a further preferred embodiment of the invention, the phase of the voltage applied to at least one of the plates is out of phase with the voltage applied to the other plates.

Further, in a preferred embodiment of the present invention, there are electrodes attached to the long and short sides, the first and second surfaces, the first and second surfaces, and at least some of the electrodes At least one rectangular piezoelectric plate that is applied with a symmetrical and unipolar pulse excitation voltage, and an elastic force source that elastically urges one side or an extension attached to the side toward an object. A micromotor for moving an object is provided.

Further, in a preferred embodiment of the present invention, at least one rectangular piezoelectric plate having electrodes attached to the long and short sides, the first and second surfaces, the first and second surfaces, and one Select a source of elastic force to elastically urge the side, or one or more side extensions, against the object, and a symmetric and unipolar pulsed or AC excitation voltage for at least some of the electrodes There is provided a micromotor for moving an object consisting of a voltage source for applying a voltage and an object.

Further, in a preferred embodiment of the present invention, there are electrodes mounted on the long and short sides, the first and second surfaces, the first and second surfaces, at least some of the electrodes being excited. A micro-actuator for moving an object comprising: a plurality of rectangular piezoelectric plates; and a resilient force source for resiliently urging one side or an extension of one or more sides of the plurality of plates toward the object. A motor is provided.

Furthermore, in a preferred embodiment of the present invention, a plate having a long side and a short side, a first and a second surface, a plurality of electrodes connected to the first surface and an opposing electrode connected to the second surface are provided. At least one of the electrodes is energized with a voltage to cause a force in a direction perpendicular to one side of the plate to preload the object and at least one of the other electrodes A micromotor is provided which is excited by a voltage to cause a force in a direction parallel and perpendicular to said side to move the object.

Further, in a preferred embodiment of the present invention, at least one rectangular piezoelectric plate having electrodes attached to the long and short sides, the first and second surfaces, the first and second surfaces, and at least some There is provided a micromotor for moving an object, comprising: a power supply for applying a voltage of the electrodes to establish a desired resonance mode of the piezoelectric plate; and mode suppressing means for suppressing a resonance mode other than the desired resonance mode. .

In a preferred embodiment of the present invention, the mode suppressing means comprises at least one suppressing means adapted to suppress vibrations caused by resonance modes other than the desired resonance mode.

Further, in a preferred embodiment of the present invention, 2
At least one rectangular piezoelectric plate having two long sides and two short sides, first and second surfaces;
A first ceramic spacer attached to the center of the short side and pressed against the object, and an arm having a second spacer attached to one end and having the other end attached to the second short side of the piezoelectric plate; A micromotor for moving an object is provided wherein the first and second spacers have adjacent parallel surfaces adapted to be biased against the object.

Further, in a preferred embodiment of the present invention, there are electrodes mounted on the long and short sides, the first and second surfaces, the first and second surfaces, at least some of the electrodes being excited. A micromotor for moving an object, comprising: a plurality of rectangular piezoelectric plates having holes provided at regular intervals along a central longitudinal axis, and at least one lever having one end rotatably mounted in the holes. Provided.

Preferably, the other end of the lever is rotatably mounted on a fixed plate, or alternatively on a plate constrained to move only in the direction of said axis.

In all of the above embodiments, the ceramic spacer is preferably mounted on one of the short sides of the piezoelectric plate, preferably in the center of the short side. This produces an optimal drive movement on the short side of the ceramic plate. In this case, the longitudinal direction of the piezoelectric plate is substantially perpendicular to the engagement surface. In systems where sufficient space cannot be taken in the direction perpendicular to the engagement surface, according to a preferred embodiment of the present invention, an alternative ceramic micromotor is provided. Here, the movement of the short side of the piezoceramic plate is to move an object juxtaposed with the long side of the plate using a spacer attached to the long side of the plate near the corner of the long side and the short side. used.

According to this feature of the invention, the spacer moves on the short side according to a resonant movement, but the engagement surface is driven parallel to the longitudinal axis of the ceramic plate. In order to avoid symmetry of the lateral movement, it is preferred to use two juxtaposed piezoelectric ceramic plates, with the corners adjacent to each other supported by spacers.

Further, in a preferred embodiment of the present invention, first and second rectangular piezoelectric plates having first and second long sides, first and second short sides, front and back surfaces, and a first plate of the first plate are provided. The short side is juxtaposed substantially in parallel with the first short side of the second plate, each plate having electrodes attached to the front and back surfaces, each plate having a first long side at one end near the first short side. A ceramic spacer attached to the side and engaging the surface of the object, the source of elastic force applied to a portion of each plate to press the ceramic spacer against the surface of the object to provide motion to the object. A piezoelectric micromotor is provided.

[0038] In a preferred embodiment of the present invention, the elastic force source is applied to at least a part of the second long side. in addition,
Alternatively, the source of elastic force is applied to a point on a side of the piezoelectric plate where the motion amplitude perpendicular to the plane of this side is substantially zero.

Further, in a preferred embodiment of the present invention, first and second substantially rectangular piezoelectric plates spaced apart from each other, each plate having two long sides and two short sides, a front surface and a back surface. And the planes of the adjacent plates are parallel and opposite each other, the long sides of the adjacent plates are parallel, at least one fixed support engaging the first long side of the first plate, and the second plate of the first plate; At least one elastic support engaging the second long side, at least one elastic support engaging the first long side of the second plate, and at least one fixed support engaging the second long side of the second plate; The first long side of the first plate is provided adjacent to the first long side of the second plate to provide a piezoelectric micromotor for moving an object.

Preferably, each support engages each piezoelectric plate at a point on a respective long side of the piezoelectric plate, the point of movement of which is perpendicular to the plane of the long side being substantially zero. The support is slidable in a direction parallel to the long side.

Further, in a preferred embodiment of the present invention, the first and second long sides, the first and second short sides, the front and back surfaces surrounded by the long and short sides, and the plurality of connected to the front surface A point on a long side of each of a piezoelectric plate having an electrode and a counter electrode connected to the back surface, and a point at which a motion amplitude perpendicular to the long side surface is substantially zero; A resilient element engaging each said piezoelectric plate with at least some electrodes in two modes, a first mode of imparting movement to a short side in a first direction parallel to the short side. , A power source for selectively exciting in a second mode providing motion in a second direction opposite to the first direction.

In another preferred embodiment of the present invention, the micromotor further comprises a structural assembly adapted to exert symmetrical movement and force in the first and second directions. Preferably, the structural assembly includes a resilient element.

In a preferred embodiment of the invention, said voltage source applies an AC excitation voltage to at least some of said electrodes.

Further, in a preferred embodiment, the electrodes comprise a plurality of electrodes on a front surface of each piezoelectric plate and at least one electrode on a back surface of each piezoelectric plate. Preferably, the plurality of electrodes comprises electrodes in each quadrant of the front surface, and the voltage source applies an AC excitation voltage to at least some electrodes on the front surface.

In a preferred embodiment of the present invention, an excitation voltage of the same polarity is applied to the electrodes of the quadrant located on the diagonal line of each plate.

Further, in a preferred embodiment, an electrode of a quadrant between the first long side and the first short side of the first piezoelectric plate is applied with an excitation voltage of the first polarity, and the first electrode of the second piezoelectric plate is subjected to the first voltage.
A voltage having a second polarity opposite to the first polarity is applied to the electrodes of the quadrant between the long side and the first short side.

In one preferred embodiment of the invention, the power source comprises, at least on some electrodes, AC excitation voltage pulses separated by a DC voltage having an absolute value greater than the amplitude of the AC excitation voltage. Apply a pulse excitation voltage. Preferably, the pulse rate of the pulse excitation voltage substantially corresponds to the self-resonant frequency of the object.

In a further preferred embodiment of the present invention, said first and second rectangular piezoelectric plates have at least one additional electrode connected to at least one long side, and the voltage source has at least some additional electrodes. Is applied. Preferably, said at least one additional electrode comprises an electrode with a first long side near a first short side. More preferably, said at least one additional electrode includes an electrode on a second long side near the second short side.

[0049] Preferably, said voltage source applies an excitation voltage to the additional electrode, thereby increasing the movement of the ceramic spacer in a direction substantially perpendicular to said plane. Preferably, the voltage source applies, to each additional electrode, an excitation voltage having the same polarity as that of the electrode in the front quarter divided portion adjacent to the additional electrode.

In a preferred embodiment of the present invention, the first and second piezoelectric plates are elastically supported at points on the plate whose motion amplitude perpendicular to the plane is substantially zero.

In a preferred embodiment of the present invention, the elastic source is adjustable.

In a preferred embodiment of the present invention, the micromotor comprises the plurality of first piezoelectric plates and the plurality of second piezoelectric plates, and the ceramic spacer of each plate elastically presses the object. .

In a preferred embodiment of the invention, the micromotor further engages a surface of the object opposite the surface engaging the spacer to provide a reaction to the force applied to the object by the spacer. And a reverse support device. Preferably, the reverse support device comprises a piezoceramic bearing having electrodes mounted on at least one flat surface, and the voltage source applies a voltage to at least some of the piezoceramic bearings.

Further, in a preferred embodiment of the present invention, first and second ends which are pivotable about an axis and are spaced at a fixed distance from the axis on both sides, a read / write head attached to the first end, A disk drive is provided comprising a rigid arm at an end and at least one piezoelectric plate micromotor resiliently biased against a rigid element.

In a preferred embodiment of the present invention, said piezoelectric plate is stationary. In an alternative preferred embodiment of the invention, said piezoelectric plate is movable with respect to said axis.

Further, in a preferred embodiment of the present invention, the arm comprises an arm pivotable about an axis, and the arm is attached to the first and second ends, and the first end, which are spaced apart from the axis on both sides by a fixed distance. A disk drive is provided having a read / write head mounted thereon, a piezoelectric plate attached to the second end and movable with the arm.

In a preferred embodiment of the present invention, said shaft extends through said piezoelectric plate.

In a preferred embodiment of the present invention, the micromotor further comprises a rigid element biased against said piezoelectric plate.

Further, in a preferred embodiment of the present invention, a first rectangular piezoelectric plate pivotable about an axis and having two long sides and two short sides, and two long sides and two short sides, A micromotor for moving an object is provided, comprising a second rectangular piezoelectric plate having a ceramic spacer attached to a side thereof, said spacer being biased against a side of said first piezoelectric plate.

[0060] Preferably, the spacer attached to the second piezoelectric plate is urged against the long side of the first piezoelectric plate.

In some preferred embodiments of the present invention, the micromotor further comprises a rigid member located between the spacer of the second piezoelectric plate and a long side of the first piezoelectric plate against which the spacer is biased. Consisting of a bow element.

[0062]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference is made to FIG. 1 which shows one large face of a relatively thin rectangular piezoelectric plate used in a motor according to a preferred embodiment of the present invention. The surface of this piezoelectric plate (hereinafter referred to as “first surface”) has four electrodes 14, 1
6, 18, and 20 are plated or tethered to form a checker pattern consisting of rectangles each substantially covering one quarter of the first surface. I have. The opposite surface of the piezoelectric plate (hereinafter referred to as “second surface”) is preferably substantially entirely covered by one electrode (not shown). Diagonally arranged electrodes (14 and 20; 16 and 1)
8) is preferably a connecting part (juncti) of the four electrodes.
on) are electrically connected by wires 22 and 24 arranged in the vicinity. The electrodes on the second side are preferably grounded. Alternatively, these electrodes may be connected by printed circuit technology similar to the technology used to form them.

A relatively stiff ceramic spacer 26
For example, a bonding agent is attached to the short side 28 of the piezoelectric plate 10, preferably at the center of the side.

The piezoelectric plate 10 has a number of resonance modes (re
sonaces). In particular, the dimensions of the piezoelectric plate 10 are close to the resonance modes in the Dx and Dy directions (cl
osely spaced, and dimensions are chosen such that the excitation curves overlap. In particular, the preferred resonance according to the present invention, as shown in FIGS.
In the y direction, there is a 1/2 (0.5) mode resonance,
In the Dx direction, there is 11/2 (1.5) mode resonance.
However, other resonance modes can be used depending on the dimensions of the ceramic 10.

When the piezoelectric plate 10 is excited at a frequency in the band indicated as ω0 in FIG.
And Dy are excited. FIG. 3 shows an example (one configuration) of applying a voltage to a given electrode and thereby exciting two resonance modes. In this example, a voltage is applied to the electrodes 16 and 18 and the electrode 1
4 and 20 are left floating (or less preferably grounded), but the amplitude of the mode is
Is shown in The excitation in this example causes Dx to be negative when Dy is positive, so that when the movement of the piezoelectric plate 10 is blocked, the object 30 pressed against the piezoelectric plate 10 moves to the left. Become. Object 3
The zero surface is depicted as curved, like the surface of a cylinder to be rotated, but the surface may be flat if linear movement is desired.

When a voltage is applied to the electrodes 14 and 20, the electrode 1
For the excitation example shown in FIG. 5 where 6 and 18 are left floating (or less preferably grounded), the modes of Dy are the same, while the modes of Dx are in opposite phase. Yes, causing movement to the right.

In the preferred embodiment of the present invention, the piezoelectric plate 10 is prevented from moving by a fixed pair of supports 32 and 34 and two spring loaded supports 36 and 38. Have been. Support 32 ~
Reference numeral 38 contacts the piezoelectric plate 10 along a pair of long sides 40 and 42 of the ceramic at a position where the movement in the x direction is zero. These supports are designed to slide in the y-direction.

The mounting of the spring in this manner reduces the effect of wear and protects the piezoelectric plate from a certain degree of impact (a degree of shock prot.).
ection).

The spring-loaded support 44 is preferably pressed against the center of the second short side 43 of the piezoelectric plate 10 opposite the short side 28. The support 44 applies pressure between the ceramic 26 and the object 30, whereby the movement of the ceramic 26 is transmitted to the object 30. Support 4 with spring
It should be noted that 4 has a response time sufficiently longer than one period of the frequency at which the piezoelectric plate 10 is excited. Therefore, when the ceramic 26 is moving in the opposite direction of the movement given to the object 30,
The surface of the ceramic 26 pressed against the object 30 actually leaves the object for only part of its period.

In a preferred embodiment of the invention, the spring-loaded supports 36, 38 and 44 are solid, rigid rubber cylinders (springs), preferably having a Shore A hardness (a) of about 60. It has a Shore A hardness of about 60) and is preferably made of silicone rubber. In fact, such "springs" are typically O-rings (such as Parker-
It can be manufactured by cutting a portion of Hannifin (provided by the marketer by Parker-Hannifin) into a desired size. Preferably, the resonance mode of the spring should be far from the resonance mode of the piezoelectric plate used. In a preferred embodiment of the invention, a spherical or hemispherical rigid element is arranged between the spring element and the ceramic.

In the preferred embodiment of the present invention, the dimensions of the piezoelectric plate 10 are determined by Morgan Matlock.
Using a PZT piezoelectric material manufactured by Roc Inc.), it measures 30 mm × 7.7 mm with a thickness between 2 mm and 5 mm. For this example, depending on the desired speed, the weight of the object 30 (and / or the pressure of the spring 44), and the required power, 30-500 volts AC to excite the piezoelectric plate 10 Can be used. Such devices operate at frequencies in the range of 20-100 kHz and have a minimum step size in the range of 10 nanometers (nm).
(a minimum step size) and a maximum speed of about 15-350 mm / sec (or more). These are only nominal ranges and will vary depending on the material used for the piezoelectric plate 10, the dimensions, the resonance mode selected, and other factors.

In practice, larger sized ceramics
It can be between 20mm and 80mm, smaller ones can be between 3mm and 20mm. For example, very long and thin devices (eg, 3mm x 80mm) will result in very high speed motors.

By using the spacer 26 attached to the short side 28 of the piezoelectric plate 10 which is urged against the object 30, the force generated from the micromotor of a given size is reduced to the same size without the spacer attached. Increase compared to the micromotor of the first embodiment. If no spacer is installed, the short side 28 directly engages the object 30. This increase in force is the result of the resonance mode energy generated in the piezoelectric plate during excitation being concentrated on the spacer.

Preferably, spacer 26 should not affect the resonant mode of the system. It is also desirable to achieve the maximum possible amplitude for motion in the x direction for a given power output. These goals may be achieved by using extremely thin spacers. However, spacers that are thinned in terms of resonance frequency are often impractical because they are often too thin. A more practical solution according to the preferred embodiment of the present invention is to use 2/2, 3
The use of a spacer having a length almost equal to the / 2 or 4/2 wavelength. Spacer 26 is made of 99% aluminum. Due to the material difference between the ceramic and the spacer, the half-wavelength of the resonance mode of the spacer is almost three times shorter (about one-third the length) than the half-wavelength of the same frequency ceramic. . In fact, about 4 to
A ceramic spacer having a length of 5 mm has been found to be suitable.

In the embodiment described above in connection with FIGS. 1 to 6, the piezoelectric plate 10 in FIG. 1 is excited by an alternating voltage at a frequency close to the resonance of the piezoelectric plate. In the method depicted in FIGS. 7 and 8, excitation is by a pulsed unipolar voltage. In this pulsed excitation embodiment according to the present invention, the electrodes 14, 16, 18 and 20 are not connected in a fixed manner as in the embodiment of FIG. 1, but will be described below. Are connected in different ways, depending on the minimum steps required.

The principle of operation of the pulse method is shown in FIG. In this figure, electrodes 14 and 18 are excited by a positive DC voltage and electrodes 16 and 20 are excited by a negative DC voltage with respect to the electrodes on the second surface of piezoelectric plate 10. Under this excitation, the piezoelectric plate 1
The left side 10 of 0 is longer than the right side (highly exaggerated in FIG. 7) and the ceramic 26 moves to the right. Of course, when no voltage is applied, the ceramic returns to its original position.

However, an asymmetric voltage pulse, for example FIG.
The present inventor has found that when a voltage pulse such as that shown in Figure 2 is applied to the electrode, the object will not return to its starting position by the ceramic 26 while returning to zero. Preferably, the fall time of this pulse should be at least four times longer than the rise time. The total pulse time (a total
The pulse time is preferably between 10 and 50 milliseconds, but the exact time depends on the mass moved by the piezoelectric plate and the force of the spring 44. In the experiments, excellent results have been obtained with a rise time of 1 microsecond and a fall time of 15 milliseconds. The minimum step in this example depends on the pulse voltage and can vary from 2 to 6 nm for a peak voltage of 30 to 100 volts,
For larger masses, the minimum step is increased due to increased inertia. This mode is not generally used for large movements, but is useful for the final stage placement of the object to be moved. Reverse the polarity of the excitation, or
Increasing the rise time and decreasing the fall time results in movement in the opposite direction. The behavior of objects in this mode is not well understood,
Extremely small minimum steps can be realized.

Alternatively, a voltage is applied to only one electrode pair, while the other electrode pair is grounded or left floating.

In an alternative embodiment where the motor operates in a pulsed fashion, the same voltage is applied to electrodes 14 and 16 and voltages of opposite polarity are applied to electrodes 18 and 20 (or are grounded or floating). Left behind). Such a voltage application (electrification) also causes a very small movement.

Another example of exciting the electrode with such a pulsed voltage provides another minimum step value. For example, the electrode 14 is excited by a positive pulse, and the electrode 16 is excited.
Is excited with a negative pulse (while electrodes 18 and 20 are grounded or left floating), a minimum step of about 2-5 nm is obtained. By exciting electrodes 18 and 20 with positive and negative pulses, respectively (while preferably electrodes 14 and 16 are left floating), a minimum step of 5-8 nm is obtained. When a pulse of one polarity is applied to electrodes 14 and 18 and a pulse of the opposite polarity is applied to electrode 20 (electrode 16 is floating),
A minimum value of similar value is obtained. As an alternative, the above-identified floating electrode could be grounded, but this would reduce efficiency.

In a particularly useful differential mode, a positive pulse is applied to the two electrodes 14 and 20 while
The two electrodes 16 and 18 are grounded and floated,
Alternatively, a negative pulse is applied. In this mode, very small minimal movements can be achieved in the range of 0.1 to 2 nm. Pulses of voltages of the same or different amplitudes may be applied to the diagonal electrodes.

Excitation by a pulse voltage is preferably performed as shown in FIG.
SU69349, described above, for example, wherein each electrode is separate and excitable.
It is also useful when applied to prior art shapes such as the No. 4 shape.

In the preferred embodiment of the motor according to the present invention, the piezoelectric plate 10 first generates a high-speed movement near the target position, as described with reference to FIGS. It is excited by an AC voltage and then by a pulse voltage as described above with reference to FIGS. One preferred embodiment of the motor system including the arrangement for such excitation is shown in block diagram form in FIG.

As shown in FIG. 9, the control system 50 includes, for example, applying energy to a pair of regulated voltage regulator power supplies 54 and 56, and four switch / modulator circuits 58, 58, respectively. 60,62
, 64 and a microcontroller 52 that controls Each of the switch / modulator circuits is connected to one of the electrodes 14, 16, 18 or 20. The electrodes on the second side are preferably grounded via tuning inductor 66.

The microcontroller 52 is preferably
A position signal is received from a position indicator (or position detector) 68 that indicates the position of the object 30 and provides feedback to the microcontroller 52. The microcontroller 52 also preferably receives the position (or movement), and optionally the user interface 70
Receive speed command from

In operation, the microcontroller 5
2 receives the position command from the user interface 70 and compares it with the actual position indicated by the position indicator 68. If the command is a move command, its position is stored for later comparison.

The microcontroller 52 stores the amount of motion required, based on predetermined optimization criteria, whether the AC or pulse mode is appropriate, and the direction in which most objects are moving. Determines which direction it is. A plurality of suitable signals are provided such that the piezoelectric plate 10 operates in a suitable excitation configuration as described above.
The signals are output to the switch / modulator circuit such that either an AC voltage or a pulse voltage (or no voltage or ground voltage) is generated and applied to each electrode. The remaining distance to be moved is reduced below the appropriate level, and the microcontroller 52 switches to the high resolution low speed mode utilizing appropriate pulse excitation as described above with reference to FIGS. . Some variation in the excitation mode may be made as appropriate when high positional accuracy is desired. When the object 30 reaches the target position, the excitation of the plurality of electrodes is terminated.

An inductor 66 is used to tune the electric resonance of the piezoelectric plate 10 and the wiring connected thereto to the same frequency as the mechanical resonance of the piezoelectric plate 10. The electric circuit includes the first and second piezoelectric plates 10.
Because most of the capacitance formed by the multiple electrodes on the surface of the surface is "set out of tune"
And to improve the efficiency of the system, it is appropriate to add an inductor, for example inductor 66.

Although the control of the movement of the system has been described for a closed loop system, open loop operation with lower accuracy is also possible. For closed loop operation, we believe that the system can achieve accuracy better than about 0.5 nm. For open loop operation, the amount of motion can be estimated fairly accurately, and the position can be controlled to within about 0.1% to 1% of the total amount of motion.

According to a preferred embodiment of the present invention, at least one constraining member is used to increase the performance of the micromotor by suppressing resonance modes other than the desired resonance mode.
FIG. 32 shows a configuration in which two restraining members are used, and FIG.
3 shows a form similar to FIG. 32, which shows the ceramic 10 for the desired mode with emphasis on departure from actual dimensions. The restraining members 300 and 302 tightly attached to the contour of the piezoelectric plate 10 can be made of thread or wire, and can be bonded to the piezoelectric plate. The members 300.302 can also include plastic or metal moldings. Member 300.30
2 is a point where the dimensional change is 0 in the X direction relating to the desired mode of operation, that is, approximately 1
/ 6 and approximately 5/6. Other modes have dimensional changes at one or both of their locations and are thereby suppressed. In such a configuration, the motion amplitude of the spacer 26 can be increased by reaching 30% compared to the motion amplitude obtained with the same input power in a micromotor without a constraining member. Reference numeral 300 or reference numeral 302
Only one of the constraint members is used.

In a preferred embodiment of the present invention, FIG.
As shown in FIG. 7, in order to increase the output of the micromotor and smoothen the movement of the object pressed by the spacer, the fixed arm 310 is connected to the short edge of the piezoelectric plate 10 with respect to the spacer bearing edge. Attached to. The arm 310 is preferably mounted substantially parallel to the surface of the piezoelectric plate 10, and one end of the arm 310 is mounted to the short-circuit end 43 of the ceramic 10 via the vertical member 314. The spacer 312 pressed and attached to the object 30 is attached to the other end of the arm 310 near the end of the ceramic 10 to which the spacer 26 is attached.

There are many other preferred forms of the embodiment of FIG. In one such form, the spacer 312 is preferably ceramic and the vertical member 314
Is preferably made of aluminum. In this configuration, special care must be taken to prevent the vertical member 314 from shorting the electrodes on the first surface of the piezoelectric plate 10. In another form, the vertical member 314 is ceramic. In the above-described embodiment, the vertical member 314 can be attached along the entire short-circuited end 43, or can be attached only to the central portion of the short-circuited end 43 by, for example, a ceramic spacer.

In the embodiment shown in FIG. 3 or FIG. 5, the excitation (excitati) of the piezoelectric plate 10 by the AC voltage is performed.
One use of the form described above in connection with (on) is an out-of-phase operation (180 ° phase difference) of spacer 312 with respect to spacer 26, as shown in FIG. As a result, the force acting on the object 30 is doubled and the movement of the object 30 is smoother than a micromotor without such an arm.

Further, another excitation (excitati) of the element 10 is performed.
ons) and configurations, as described herein, can be used in connection with the apparatus shown in FIGS. In a preferred embodiment of the motor according to the invention, a plurality of piezoelectric plates can be formed to increase the output of the motor and to reduce the variability existing between different devices. One such configuration, shown in FIG. 10, is that the two piezoelectric plates 10, 1 are in a comb configuration.
0 'is provided. That is, the two piezoelectric plates 10, 10 'in the direction of operation induced by the piezoelectric plates 10, 10'.
10 'is mounted in comb form. The two piezoelectric plates can be driven by a common control system such as the control system 50 shown in FIG. 9 or a separate control system. For clarity, the control system and electrical connections are not shown in FIG.

As shown in FIG. 10, the piezoelectric plates 10,
A spacer unit 74 located in the middle of 10 ′ supports and separates the piezoelectric plate. Four spring-biased side supports 76 and two spring-biased end supports 78 support the piezoelectric plate pairs in the same manner as described above in connection with the embodiment of FIG. actually,
The piezo plates 10, 10 'are preferably restrained from moving perpendicular to the surface of the piezo plates by extension of the spacer unit 74 and spring biasing supports 76, 78. Such a configuration is shown in FIG.

FIG. 11 shows six piezoelectric plates formed in a comb / parallel configuration of two units and three units. Due to the limitations of the illustration, the mechanism of the spring biasing support and the pressing spacer unit 74 with respect to the piezoelectric plate is not shown, but the preferred supporting mechanism is shown in FIG.
It is shown in. Other forms, 2 × 4 comb / parallel, are also useful.

In the preferred embodiment of the motor according to the invention, the piezoelectric plates used in the embodiments shown in FIGS. 10 and 11 are not all the same. In this embodiment of the invention, the one or more piezoelectric plates are PZT
-8 (manufactured by Morgan Matroc Inc.), and one or more piezoelectric plates such as PZT-5H (manufactured by Morgan Matroc Inc.) Made of soft material. 2 above
Two types of materials have the same x, y dimensions and the same resonance (reso
nance) and can be physically shaped such that the resonance frequency is obtained by adjusting the thickness of the individual piezoelectric plates. Also, both materials can be used at the same thickness. In such a configuration, the soft material broader Q described above is such that both the hard and soft materials are fully excited at the same frequency.
e) would assume that

When the soft piezoelectric plate is charged, the resonance width increases in both Dx and Dy,
The portion (time) during which the ceramic 26 contacts the object is greater than for the rigid piezoelectric plate. However, due to this property, the driving force acting on the soft piezoelectric plate is reduced, and the operation unevenness is also reduced.

In a preferred embodiment of the present invention, where both types of piezoelectric plates are used, as described in the preceding paragraph, a rigid piezoelectric plate has the ability to reduce traction and other inertial forces and a soft piezoelectric plate. The plate is
There is the ability to provide a smoother and more accurate movement on smooth stop and start than when only a stiff piezoelectric plate is used.

In a preferred embodiment of the present invention, the two types of ceramic are out of phase with each other (180 ° out of phase). In this case, the two types of ceramics are essentially independent of each other (excitation cycle).
at different parts of the cycle), resulting in minimal friction due to the different movements of the two types of piezoelectric plates. In a preferred embodiment of the present invention, phase reversal is achieved by using two ceramics with reversed polarization directions. Also, a voltage out of phase can be applied. The anti-phase operation of the ceramic is also beneficial when two piezoelectric plates of the same characteristics are used.

XY having all the advantages of the present invention
Exercise is also possible. One form of producing XY motion is shown in FIG. The integral X-shaped section 90 is formed of a piezoceramic material and has front and rear electrodes formed on the large flat inner surfaces of the section. The inner surface, not shown (and with respect to the surface shown completely or partially), is provided with a single electrode arranged over the entire surface. Those single electrodes are grounded (or connected to the system power common return) and, according to a preferred embodiment of the invention, the electrodes shown are activated according to the mechanism described above. Configuring an XY table with such a device only requires the addition of a flat table that holds the ceramic and contacts the ceramic 26 as described above with reference to FIGS. Multiple X-shaped sections 9 of the same or different ceramics
0 is a parallel-as described above with respect to FIGS.
It can be used in comb form.

FIG. 13 shows a second embodiment, in which two piezoelectric plates as shown in FIGS. 1 to 5 are integrally fixed, and the movement in the X direction at one end and Achieve movement in the Y direction at the other end.

An XY table 100 using the configuration of FIG. 13 and constructed as a preferred embodiment of the present invention.
Is shown in simplified form in FIG. The table 100 has a fixed base 102 and a top 10
13 and two piezoelectric plates 10 sandwiched between the support members 106, 108, 11
0, 112, 114 and 116, 118 and 120
Are added to the supports 32, 34, 36 and 38 of FIGS.
Identical in shape and function. Supports 106 to 12
All zeros are provided integrally with the fuser (not explicitly shown), but are not attached to the base 102. However, it is preferable to provide a slider that is allowed to slide between the fixed material and the base 102 in the X direction (indicated by the arrow 122), and is attached to the fixed material.

A set of sliders 124, 126 and 1
Reference numeral 28 is provided to allow the top 104 to move with respect to the fixed material in the Y direction indicated by the arrow 130. The sliders 124 to 128 are preferably attached to the fixing material.

In short, the fixed material has upper and lower piezoelectric plates 10 and a support for a slider, and the slider is fixed to the base 102 in the X direction and to the fixed material in the Y direction. The slide movement of the top 104 is allowed.

In use, the excitation of the lower piezoelectric plate is:
Move it in the X direction. Since the top 104 is restricted from moving in the X direction with respect to the fixed material by the fixed material, the top 104 moves in the X direction by the same amount as the fixed material. Thus, the excitation of the lower piezoelectric plate causes an X-motion of the top 104. When the upper piezoelectric plate is excited, the top 104 moves in the Y direction with respect to the fixing material. The top 104 moves with respect to the base 102 because the fixed matter is regulated to move somewhat in the Y direction with respect to the base. .

The selective excitation of the upper and lower piezo plates is accomplished by the X of the top 104 relative to the base 102.
-Y operation, which has all the advantages of the linear motion embodiment shown above for the embodiment of FIGS. Exciting only one of the piezoelectric plates causes movement in only one direction.

It is possible to use the principles outlined for X, Y, Z motion, X, Y, Θ motion, or motion directions along a plurality of non-perpendicular axes. May be provided with different ceramics.

Further, two tandem and series arrangements of piezoelectric plates of different or identical parts are described with reference to FIG. 10 and FIG.
As in the case of the individual column arrangement, the same utilization as described above is caused.

The use of a piezoelectric plate according to the invention to achieve a rotational movement is illustrated in FIG.
A two-row configuration of piezoelectric plates 150 similar to that shown at is applied along cylinder 152 and to rotate cylinder 152. With such a form, the surface of the ceramic spacer 26 preferably has a concave shape along the surface of the cylinder 152. A single piezoelectric plate similar to that shown in FIGS. 1-5, or some of the annularly arranged piezoelectric plates
It can be used instead of 50.

When the circular movement and three-dimensional positioning of the sphere are required, the configuration as shown in FIG. 15 is similar to the configuration 150 for rotating and positioning the sphere, in which three orthogonally arranged ceramics are arranged. By providing the composition, it is used after being modified. If only rotation (and 3
(No dimensional positioning is required), two orthogonal drives are sufficient. In this embodiment, the outer surface of the ceramic 26 is formed along the surface of the sphere.

When using the present invention, speed, accuracy,
It is possible to improve the combination of driving forces. By using only a single ceramic pad 26, greater force can be used to push the ceramic against the object 30 than in the prior art for cracking where excessive force is required. The use of two tandem ceramics unexpectedly results in increased driving force and speed. In general, both higher speeds and higher driving forces can be achieved simultaneously with the same volume of piezoelectric plate in the present invention.

Also, the present invention is based on the fact that when the rectangular electrodes shown in the previous embodiment are used, the movement is not perfectly straight, ie, due to the rotational characteristics of the movement of the ceramic 26, the ceramic 26 It can be seen that only a portion contacts the moving object 30. 14 ', 16',
If 18 'and 20' are non-rigid electrodes of the straightened version shown in the previous figure, this can be improved, for example, by cutting the electrodes as shown in FIG. Although the sinusoidal change is shown in FIG. 16, other electrode shapes can also be modified to straighten the device.

FIG. 36 shows an example of a preferred embodiment of the present invention.
It is used to make the movement of the object 30 symmetrical in the opposite direction along the axis. If this arrangement is used substantially, the same forces and amplitudes can be applied in the X and -X directions. The arrangement shown in FIG. 36 corresponds to the X, Y shown in FIG.
It has two parallel piezoelectric plates 10, 10 'oriented in the same direction in the XY plane defined by the directions.

As shown in FIG. 36, the piezoelectric plates 10,
The movement of each of 10 'is restricted by a pair of fixed supports 32 and 34 and a pair of elastic supports 36 and 38. The supports 32 to 38 are each made of the long side 4 of each ceramic.
0, 42 and points 40 ', 42' at which the motion amplitude in the X-axis direction is almost zero,
Supports 0 '. The supports 32 to 38 are preferably slidable in the Y-axis direction.

The fixed supports 32 and 34 have the long sides 4
At 0, the piezoelectric plate 10 is engaged, while for the piezoelectric plate 10 ', the fixed supports 32, 34 are engaged with the long sides 42'. The elastic supports 36, 38 engage with the long sides 42 of the piezoelectric plate 10, while for the piezoelectric plate 10 ', the elastic supports 36, 38
0 '. With this arrangement, the error in the amount of movement in the X and -X directions caused by one piezoelectric plate is compensated for by another piezoelectric plate of the same configuration but opposite in support form.

An alternative arrangement for providing symmetrical movement along the X axis is illustrated in FIG. 37 as a preferred embodiment of the present invention.

FIG. 37 shows an apparatus having two identically constructed assemblies 320 and 340. The assembly 320 consists of two rigid bodies 322 and 324, which are connected by hinges 326 and mounted on a base (not shown) by hinges 328 and 329, respectively. Similarly, the assembly 340 is mounted on the base by hinges 327, 341 and 342, respectively.

The hinges 326 and 327 extend through holes formed in the surface of the piezoelectric plate 10. Hinge 3
Holes for 26 and 327 are located between the two electrodes along the short side, for example, between electrodes 14 and 16 and between electrodes 18 and 20, respectively, at locations where they do not operate along the X axis. Preferably it is. In a preferred embodiment of the invention, hinges 326 and 327 are 1/6 and 5 /
The length is 6 and is apart from the short side 28.

Preferably, each element 322 has two arms 330 and 331 on the opposite side of ceramic 10, and each element 324 has arms 334 and 335 on the opposite side of ceramic 10. As a result, the ceramic 10 is
0 and 331 and between the arms 334 and 335. Elastic elements 337 and 338 are provided with arms 330 and 3 of element 322.
31 and between the arms 334 and 335 of the element 324. Elastic element 33 of assembly 320
7 and 338 impart elasticity to the piezoelectric plate 10 at about 1/6 the length of the ceramic, and similar elements of the assembler 340 impart elasticity at about 5/6 the length of the ceramic 10.

In one typical device, the piezoelectric plate 1
0 is constituted by PZT · 4 and has a length of 300 mm;
It has a width of 7 mm and a thickness of 3 mm. The elastic elements 337 and 338 in this device are 5 mm long and have a diameter of 2.5.
・ It is a silicon cylinder with a 3 mm shore hardness of 60/70. The elastic element 44 has a length of 5 mm and a diameter of 2.5 mm
Thus, a force of about 5 N (Newton) can be applied to the short side 43 of the piezoelectric plate 10. As shown in FIG. 3 or FIG. 5, when the piezoelectric plate is excited with AC 200.300 V and this device is used, a resolution of 0.1.0.3 μm and a speed of up to about 400 mm / sec are obtained. Is obtained.

In the preferred embodiment of the present invention, an electrode having the shape shown in FIG. 17 is used. For this embodiment, an additional electrode 150 is applied to the piezoelectric plate in addition to the electrodes 14, 16, 18, 20. The electrode 150 preferably extends to the same width as the ceramic 10 and is excited by a DC voltage or a harmonic voltage used on other electrodes. As a result of such excitation, the ceramic 10 is stretched and preloads the motor on the object to be moved. By using harmonic excitation, this preload is synchronized with respect to the other electrodes, increasing the contact time between the ceramic 26 and the moving object. In theory, it would be possible to omit the spring 44 from such a system, but in practice some resilient biasing force (which reacts more slowly than a piezoelectric plate) is used and may even be necessary. A similar effect is obtained from the embodiment of FIGS.

FIG. 20 shows another mounting means applicable to both a single motor and a plurality of ceramic motors.
In this mounting means, holes are formed at the center of the piezoelectric plate 10 and at 1/6 and 5/6 positions on the center line thereof. These holes have thicknesses 20 and 30 of the ceramic 10.
%. Pin 152 is approximately ± 10
It is disposed in the hole with a gap of 0 μm, and at least one end is attached to one end of levers 154, 156, 158. The pins are formed of a material having the same acoustic velocity as transmitted in the ceramic 10. The pins may be made of metal, ceramic or other suitable material.

For the resonance mode of the ceramic 10 used in the preferred embodiment of the present invention, the ceramic moves only longitudinally around the perforations. In fact, the central hole hardly moves. When the other end of the lever is rotatably attached to the fixed object 160, the ceramic 10
Is moved only along its longitudinal direction. Thus, the springs 36 and 38 can be removed. In addition, the spring 44 is replaced by a spring 44 'which pushes one of the levers in the direction in which the object is moved and biases the motor. Many such springs are used to bias other levers.

A similar principle applies only to mounting two juxtaposed piezoelectric plates 10 and 10 ', as shown in FIG. In this arrangement, the piezoelectric plate 10
And 10 'are the five levers 16 used in the means described above.
2, 164, 166, 168, 170. It should be noted that lever 170 is preferably a single-piece lever attached to the center of both ceramics and secured to the center of plate 172. The other lever is rotatably mounted at one end to one hole of ceramic and rotatably mounted at the other end to the plate 172. Each ceramic 10 and 10 'has a spring 4 at the lower end.
4 separately.

In another form, the ceramics 10 and 10 '
Is not biased by a spring. However, the plate 172 can only move vertically,
The lower end is urged by a spring (not shown) to urge the ceramics 10 and 10 'against the object to be moved. The various width dimensions of the mounting means, of course, can be technically improved by using this principle in these preferred embodiments.

The main advantage of mounting a piezoelectric plate on the above-mentioned pins is to significantly lower the temperature of the ceramic, which is achieved by removing heat from the mounting location. The mounting position is also a hot part in the preferred mode of operation. In particular, the temperature at these locations can be reduced from 50.80 ° C. to about 30 ° C. by using this means.

When the heat transfer from the ceramic to the pin is good, the cooling effect of the pin is enhanced. In order to ensure such heat conduction, the pins should be thermally conductive and fixed in a relatively soft material, for example an elastomer covering the inner wall of the hole. One suitable material is epoxy, which is used in an insufficient amount to cure. Such a resilient material is sufficient to rotate the pin small and partially in the hole. In a preferred embodiment of the invention, the epoxy (of the same material as the piezoelectric plate itself)
About 40% PZT powder is filled. Such a filling allows the acoustic velocity in the epoxy to be matched to the piezoelectric plate.

The movement of the device can be measured based on the amount of time that the ceramic 26 is in contact with the moving object. To facilitate such measurements, the surface of the ceramic facing the object to be moved is coated with a metal and the electrodes are in contact with this coating. For this purpose, the coating extends to the side of the ceramic 26. The object to be moved is made of metal (or having a metal coating), and the contact time is reduced by ceramic
Can be measured as the short circuit time between the metal coating of the object and the object to be moved.

FIGS. 22, 23 and 24 show the case where a ceramic motor is applied to drive the stage.
Used as an optical disk reader such as a player. In such an apparatus, the stage 160 has holes 164.
Is formed, and an optical reader (not shown) mounted on the stage 160 detects (and reads) the optical disk through the hole 164.

In FIG. 22, the stage 160 is mounted on two rails 162 and a ceramic motor 166.
The ceramic motor is preferably of one of the types described herein and is movably provided on one edge of stage 160 for moving the stage along the rails.

23 and 24, one edge of the stage 160 is mounted on a rail, and the other edge is engaged with the worm 168 by the rack 170. The ceramic motor 172 is preferably of one of the types described herein and drives a wheel 174 mounted on one end of the worm. 23 and 24 differ in the way the motor drives the wheels.

In all of the embodiments described above, the spacer between the ceramic plate and the surface on which the micromotor is mounted is mounted on one of the short sides of the ceramic plate, preferably at the center of the short side. The longitudinal direction of the plate is perpendicular to the mounting surface. This arrangement is preferred because the optical drive operation is obtained on the short side of the ceramic plate. However, in some applications, for example, when the motor is positioned between the slide and its housing,
There is a limit to the space available perpendicular to the mounting surface, which is shorter than the longitudinal direction of the ceramic plate. To solve this problem, the present invention provides another ceramic micromotor. That is, the longitudinal direction of the ceramic plate is parallel to the mounting surface, but the vibration generated on the short side of the ceramic plate is available.

In this embodiment of the present invention, the ceramic spacer is attached to one end of the long side of the piezoelectric plate, and is attached to a surface parallel to the long side. Since the spacer so attached is arranged near the short side of the ceramic plate, the spacer vibrates according to the resonance operation appearing on the short side. This vibration of the spacer results in movement of the surface or micromotor that engages the spacer. Its movement depends on the fact that both are constrained parallel to the longitudinal direction of the ceramic plate. However, arranging the spacer at or near the end rather than the center of the long side of the plate creates an asymmetric movement of the spacer. Thus, the movement of the mounting surface or micromotor in one direction is different, for example less powerful or slower than the corresponding movement in the other direction. In order to eliminate this asymmetry, it is preferable to use a pair of piezoelectric ceramic plates as described later.

FIG. 25 schematically illustrates a pair of piezoelectric micromotors 200 mounted on a surface 210.
See now. In the non-paired embodiment described above, movement of either surface 210 or micromotor 200 is constrained, allowing other movements, depending on the applied force. The micromotor 200 is preferably
It has two piezoelectric plates 212 and 214 mounted in a housing 220 made of aluminum. Housing 220 is preferably pressed against surface 210. The outer short sides of the plates 212 and 214, ie, the right side of the plate 212 and the left side of the plate 214 illustrated in FIG. 25, are preferably in a horizontal direction formed of a relatively stiff material such as, for example, a ceramic material. Is supported by the support member 222. The inner short sides of the plates 212 and 214, ie, the left side of the plate 212 and the right side of the plate 214, are preferably provided by a resilient connecting member 226, preferably formed of a rigid rubber or plastic material. Supported. Plates 212 and 214 are supported from their bottom by a bottom support member 224, which can be formed of the same material as member 226, or preferably, a stiffer material.

According to a preferred embodiment of the present invention shown in FIG. 25, spacers 21 preferably made of ceramic
6 is attached to the upper long side of the plate 212 at its left end (according to the arrangement of FIG. 25; the same applies hereinafter), and a similar spacer 218 is attached to the upper long side of the plate 214 at the right end thereof. Spacers 216 and 218 are functionally engaged with surface 210 when micromotor 200 is pressed against surface 210. In a preferred embodiment according to the present invention, the housing 220 comprises
Preferably, there is provided a protective frame 215 formed or coated with a low-friction material such as Teflon, for example, the frame 215 comprising spacers 216 and 218.
At least partially separate from the area of the mated and attached surface 210 to prevent unwanted matter, such as debris, from accumulating on the surface 210.

The four electrodes are plated to form a checkerboard-like pattern electrode having a plurality of rectangular shapes, or otherwise the piezoelectric plate 212
And 214, wherein each of the plurality of rectangles of patterned electrodes substantially occupies one quarter of the front surface, as described above with reference to electrodes 14, 16, 18 and 20 in FIG. Cover. The back surface of each piezoelectric plate is substantially entirely covered with one electrode (not shown), as described above with reference to FIG. As in the embodiment of FIG. 1, the two diagonally located electrodes are electrically connected by a plurality of wires 230 preferably located near the junction of the four electrodes. Multiple electrodes on the back of each ceramic plate
Preferably it is grounded. Alternatively, the plurality of electrodes may be connected by a technique similar to the printed wiring technique used to form the plurality of electrodes.

The plurality of electrodes on the plates 212 and 214 are preferably driven by an excitation circuit illustrated in block diagram form in FIG. The excitation circuit includes, for example, a controller that is a microcontroller 244 that controls the application of energy to the voltage regulated regulator power supply 242 and the switch / modulator circuit 240. The switches in the switch / modulator circuit 240 are connected to the plate 2 via wires 234 and 236 or equivalents, such as printed wiring electrode patterns.
Connected to each preselected group of electrodes on the front of 12 and 214. Ceramic plates 212 and 2
The plurality of electrodes on the back of 14 preferably
6 and a tuning circuit comprising a coil 248.

Apart from the special excitation modes described below, the plurality of electrodes on each ceramic plate 212 and 214 can be used to provide a micromotor 200 having the desired characteristics according to a given application. It may be interconnected and excited according to any of the modes described above with reference to the unpaired embodiment. Similarly, ceramic spacers 216 and 218 may be formed of relatively soft or relatively hard ceramics, as in the embodiments described above. However, plate 2
The excitation of the plurality of electrodes on
10 and spacers 216 and 21 in the same horizontal direction.
In order to obtain a movement of 8, it is necessary to invert compared to the excitation of the electrodes on the plate 214.

26, which illustrates a plurality of preferred xy resonance modes in the piezoelectric plates 212 and 214, and which shows a simplified and schematic view of a portion of the micromotor 200. As shown in FIG. 26,
The plurality of electrodes on plates 212 and 214 are preferably two groups of electrodes, electrode 254 and electrode 25.
6 is divided. The excitation voltage applied to electrode 254 generally has a polarity opposite to the polarity applied to electrode 256, ie, a positive voltage is applied to electrode 254 when a negative voltage is applied to electrode 256. , And conversely, voltages are applied.

The spacer 216 is attached to the left end of the plate 212, while the spacer 218 is
14, the excitation method in FIG. 26 is such that the two spacers are in the same direction along the Y axis,
That is, when moving in the up-down direction, the spacers 216 and 218 in the same direction along the X-axis, that is, in the left-right direction
It should be recognized that Thus, spacers 216 and 218 always move in the same direction relative to surface 210 as desired. According to this excitation method, a schematic graph of the X and Y resonance modes of the piezoelectric plates 212 and 214
4 is shown schematically below. As further illustrated in FIG. 26, the bottom support member 224 is preferably provided below a plurality of points on the plates 212 and 214, where the movement along the Y axis, ie, Δy, is substantially To zero. This improves the stability of the micromotor 200 and maximizes the amplitude obtained by the micromotor 200 along the y-axis.

Electrode 25 according to a preferred embodiment of the present invention
4 and 256 provided in microcontroller 24
Reference is now made to FIG. 27, which schematically illustrates the pulse-shaped excitation signal controlled by FIG. 4 (FIG. 25). The excitation signal of FIG. 27 comprises a plurality of pulses of a driving excitation voltage separated by a predetermined DC voltage interval that operates to move the plurality of spacers without contacting the surface 210. In FIG. 27, the voltage difference between the upper peak of the excitation voltage and the lower peak of the excitation voltage is indicated by “A”, and the DC voltage between pulses is indicated by “B”. I have. According to this embodiment of the invention suitable for the unpaired micromotor described above, the pulse rate of the excitation signal is set substantially according to the self-resonant frequency of the object mounted by the micromotor. .

Typical resonance frequencies of objects driven by the micromotor, ie 300 Hz
Are generally much lower than the driving AC frequency used, and each pulse contains the actual number in the period of the driving AC. The DC voltage B applied to the electrodes 254 and 256 (see FIG. 25) between the pulses generally comprises spacers 216 and 21
8 is lower than the lower driving frequency peak or higher driving frequency depending on whether electrode 254 or 256 is driven so that 8 moves away from surface 210 between pulses. Higher than the peak. Thus, the driven object autonomously moves between pulses. This correlation between the pulse rate of the excitation signal and the self-resonance of the matingly mounted object is destructive between the driving pulse and the response of the driven object in response. Prevent interference.

Reference is now made to FIG. 28, which schematically illustrates an alternative electrode configuration on ceramic plates 212 and 214. According to this embodiment of the present invention, additional electrodes 260 are provided on the upper and lower sides of plates 212 and 214. The plurality of electrodes 260 are preferably excited by the same plurality of excitation voltages used to drive the plurality of electrodes 256 (FIG. 26).
In this configuration, the amplitude of the movement of the spacers 216 and 218 along the Y axis is greater than the amplitude of the movement of the plurality of spacers along the X axis, as shown schematically above the spacers 216 and 218. It should be recognized that it is large. In contrast to the substantially circular movement of the plurality of spacers in FIG. 26 schematically illustrated over the plurality of spacers, this movement of the slightly sloping, elliptical shape of the spacers 216 and 218 is such that Movement is spacer 21
6 and 218, providing a micromotor 200 having greater driving force and better traction (traction friction) between the plurality of spacers and the surface 210 because it increases the time of contact between the surface 210.

Reference is now made to FIG. 29, which illustrates a variation of the mounting structure of the piezoelectric plates 212 and 214. In addition to the horizontal support member 222 and the connecting member 226, plates 212 and 214 are under the plate 212 and the plate 214 and between them, the housing 220 (FIG. 2).
It is supported by the base 266 mounted in 5). The plurality of plates 212 and 214 are also supported by a plurality of preferably resilient holders 262. One end of each holder 262 is preferably rotatably mounted on a respective mount (mount) 265 fixedly mounted to the housing 220, while the other end of each holder 262 is connected to a respective one of the plates 212 or 214. It is rotatably mounted on each pin 264 extending through the hole. The four pins 264 are preferably connected to the plate 212
And 214, two pins on each plate are mounted at multiple points where the amplitude along the P direction shown in FIG. 29 is substantially zero as described above.
In a preferred embodiment, two holders 262 are mounted on each pin 264 and one holder
It is attached to each side of 12 or 214. An elastic bottom support member 263 is preferably mounted between the lower end of each holder 262 and the lower long side of plate 212 or plate 214. Providing a plurality of holders 262 supporting the plates 212 and 214 at optimal positions as described above improves the stability of the micromotor 200. The plurality of spacers 262 are preferably tilted as illustrated in FIG. 29, thereby allowing a drive movement of the piezoelectric plates 212 and 214 along the P direction.

Another for plates 212 and 214
Reference is now made to FIG. 30, which illustrates a variation of the mounting structure. According to this structure, a plurality of pins 268, similar to the plurality of pins 264 of FIG. 29, are mounted on the plates 212 and 214, as described above, at positions where the amplitude of movement is substantially zero. You. Therefore, three pins 268 may be mounted on each plate according to the plurality of resonance modes described above. At least one spring 270, preferably a steel spring, is mounted on the plurality of pins 268 in the manner illustrated in FIG. The end of the spring 270 is preferably coupled to an adjustment screw in the housing 220 such that the spring 70 extends between two bobbins 272 mounted on a preferably horizontal support member 222. This stretching also biases the horizontal support 222 against the outer short sides of the plates 212 and 214, providing better support for the piezoelectric plate. The tension of spring 70 can be adjusted using screw 274, but controls the elasticity of plates 212 and 214 with respect to movement along the y-axis. Thereby, the contraction, speed, and force of the micromotor 200 can be controlled.

Referring to FIG. 31, micromotor 20
A preferred arrangement for engaging a zero with a relatively thin object 278 is shown. Generally, when a micromotor engages a thin object, the pulsed force applied to the object by the motor may cause the object to slightly damage or bend in the area of engagement. For this reason, the present inventor has proposed a counter bearing device 2 that minimizes this problem.
80 was devised. According to this, the preferred embodiment of the present invention, a counter-bearing device 280, includes a housing 282, which is
Is preferably fixedly connected to the housing 220 via a connector 290. At least one bearing 284 in housing 282 includes spacers 216 and 21
8 for the force applied to the front of the object 278 by
It provides rigid support for the back surface of object 278 (ie, the surface that does not engage micromotor 200). Bearing 284 may be any known bearing, for example, a metal cylinder.

In a particularly preferred embodiment of the counter-bearing device 280, the bearing 284
And 214 similar piezoceramics. In this embodiment, the ground electrode (not shown) substantially covers one flat surface of the bearing 284, while the other surface of the bearing 284 includes two separate electrodes 286 and 288, which are Cover half of the The electrodes 286 and 288 are arranged as shown in FIG. 31, ie, one above the other, and when an AC voltage is applied as described above, the bearing 284 will
Vibrates at a resonant frequency along an axis. When the bearing 284 is driven in the appropriate direction, e.g., upwards, at the y-axis frequency of the plates 212 and 214, the spacers 216 and 218 are gradually lowered, and as the spacers are raised, the micromotor 200
Provides a very effective counter-bearing for the forces applied by This embodiment of the invention has the advantage that, with appropriate structural adjustments, it can be applied to micromotors other than those described above as well.

The micromotor 200 has one plate 2
Although described as including only 12 and one plate 214, it should be understood that variations of the embodiment of FIGS. 25-31 using multiple sets of piezoelectric plates 212 and 214 are also within the scope of the invention. Must. In such a case, the sets of plates are preferably mounted parallel to one another.

In some preferred embodiments of the present invention,
A piezoelectric plate 10 is used in a disk drive for moving and positioning a read / write head. Such a configuration is shown in FIGS. FIG. 38 is a block diagram of a disk drive including a piezoelectric micromotor for moving a read / write head. Disk drive 35
0 houses a disk 352 rotatable about axis 354 and a read / write assembly 360. The read / write assembly 360 includes an arm 37 pivotable about an axis 372.
0 and the piezoelectric plate 10 used to pivot the arm 370 about the axis 372. Disc 352
Is accomplished by rotating disk 352 about axis 354 while rotating arm 370 about axis 372. Reading and writing of disk 352 is accomplished via read / write head 374, which may be any known head mounted at the end of arm 370.

FIG. 39 is a detailed view of the read / write assembly 360. As shown in FIG.
Can use any of the above types, but a through mount (through) on a fixed base (not shown).
It is preferably fixedly mounted to the slidably mounted element via mounts 385 and 386. The piezoelectric plate 10 is elastically urged against the rigid element 380 of the arm 370 by the elastic element 44. Elastic element 44
Is preferably pressed against a fixing element in a fixing base (not shown). When excited according to one of the excitation shapes described above, the stiff element 38
The spacer 26 urged toward 0 moves in either the x or -x direction depending on the voltage application state. Spacer 26 and arm 37 via rigid element 380
The relative movement between zero causes arm 370 to pivot about axis 372. As a result, the read / write head 374 moves in either the θ or −θ direction that is substantially in contact with the radius of the disk 352.

The mounts 385 and 386 are the piezoelectric plates 1
It extends through the 0 hole. The holes are preferably located between the electrodes at about 1/6 and 5/6 the length of the ceramic 10 along the longitudinal axis of the ceramic 10. At these points, the displacement and dimensional change of the ceramic 10 along the x-axis is substantially zero.

FIGS. 40 and 41 differ from FIG. 39 in that the piezoelectric plate 10 is mounted on a fixed base.
As shown in FIG. 40, the piezoelectric plate 10 can be mounted on a fixed base by a pair of fixing elements 390 and 391. The anchoring elements 390 and 391 preferably engage the piezoelectric plate 10 at about 1/6 and 5/6 of the length of the ceramic. The piezoelectric plate 10 includes the ceramic 1
Element 39 so that movement along the longitudinal axis of ceramic 10 is possible while constraining movement perpendicular to its longitudinal axis.
It may be located in a guide hole formed in 0 and 391.

As an alternative, as shown in FIG. 41, the piezoelectric plate 10 can be mounted on a fixed base by means of a resilient support element 392. The support elasticity is determined by the rigidity of the material forming the support element 392. Support element 39
Preferably, 2 is attached to a fixed base (not shown) and engages the ceramic 10 at about 1/6 and 5/6 of the length of the ceramic along the longitudinal axis of the ceramic 10.

The ends 395 and 396 of the support element 392 are
Preferably, the element 380 of the arm 370 is engaged to remove dust that has accumulated on the element 380. Protrusions 397 and 3 preferably located on the spacer-facing side of element 380 between spacer 26 and both ends 395 and 396
Numerals 98 limit the range of angular displacement of the arms 370, respectively, and suppress accumulation of dust near the spacer 26.

In a practical example, element 3 with respect to axis 372
The radius of gyration R1 of the point on
The ratio between the radius of gyration R2 of the point on the write head 374 is
It is of the order of 1 to 3, or 1 to 5. Therefore,
The linear displacement of the read / write head 374 on the disk 352 for a given angular displacement Dθ is about 3 to 5 times greater than the linear displacement of the spacer 26 for a given angular displacement Dθ.

In a preferred embodiment of the present invention, in order to increase the read / write capacity of the disk drive,
Many piezoelectric ceramics are used. An example of the arrangement shown in FIG. 42 representing two parallel piezoelectric plates 10, 10 ′ is mounted on a shaft 400. This arrangement
It can be used to simultaneously or alternatively perform reading and writing on the opposite side of a single disk in order to simultaneously perform the above reading and writing on one disk. However, for reading or writing to a single sided disc, one piezoelectric plate 10 or 10 '
Only one of them is used.

In the arrangement shown in FIG.
0, 370 'is pivotable with respect to a shaft 400 extending through a hole in the piezoelectric plates 10, 10'.

[0159] For each piezoelectric plate, the holes are preferably located between adjacent electrodes along respective short ends 28, the respective short ends being approximately 1/6 of the length of the ceramic. Away from section 28. The piezo plates 10, 10 'are fixed to a rotatable shaft 400 and can move according to the rotating shaft 400. On the other hand, the piezo plates 10, 10 'are provided with holding elements 404 and 405 so that each can be moved independently.
May be rotatably mounted on a shaft 400 fixedly held between the shaft 400 and the shaft. The holding element 404,
405 is preferably mounted on a fixed base (not shown).

The piezoelectric plates 10, 10 'are connected to the connecting elements 4
08/408 'read / write head 3
74, 374 'respectively. Element 4
08 is attached to the piezoelectric plate 10 along the long ends 40, 42, or
Is preferably gripped. The element 408 preferably engages the piezoelectric plate at a point about one-half of the length of the ceramic, and away from the end 28 that is about five-sixths shorter. The corresponding element 408 'is preferably engaged with the piezoelectric plate 10' at said 1/2 and 5/6 points along the long ends 40 ', 42'. At the １ ／ and ／ points, there are roughly points where there is no movement of the ceramics 10, 10 ′ in the x-direction, or dimensional changes. The rigid element 410 is preferably biased to the spacers 26, 26 'of the ceramics 10, 10', respectively, preferably by means of elastic elements 411.

In an actual arrangement as shown in FIG.
The radius of gyration of a point on element 410 for shaft 400 and read / write head 3 for shaft 400
The ratio of the point on 74 to the radius of gyration is from 1: 5 to 1:10
Range. As a result, with a given angle of movement Dθ, the linear movement of the read / write head 374 on the disk 352 can be 5 to 10 times greater than the linear movement of the spacer 26, respectively. .

The system, including the piezoelectric plates 10, 10 ', operates in a closed loop mode and includes a disk drive track controller (not shown) to determine the position of the write head.

In the preferred embodiment of the present invention, a number of piezoelectric ceramics are used to increase the rotational performance and increase the read / write head travel angle. FIG. 43 shows an example of such an arrangement, in which three piezoelectric ceramics are used. A pair of piezoelectric plates 10 ', 10 "are provided with a shaft 4 suitably mounted on a fixed base (not shown).
It is used to rotate the piezoelectric plate 10 with respect to 20. The spacer 26 attached to the piezoelectric plate 10 is urged to the end 440 of the arm 370. The force exerted by the spacer 26 on the end 440 of the arm 370 depends on the movement of the spacer 26,
And read / write head 3 attached to it
The rotation of shaft 74 about shaft 372 is caused.

In the preferred embodiment of the present invention, as described above with reference to FIG.
0 ″ is fixed with respect to the shaft 420 and
The fixed base can be attached to the fixed base (not shown) by a shaft attached to an element slidably mounted to the base. On the other hand, the piezoelectric plates 10 ', 10 "can also be mounted on a fixed base by means of fixing elements, as shown in Fig. 40, or by other methods described herein. Extending through a hole located at the center of the 10 and preferably at the intersection of the four electrodes of ceramic, the spacer 26 'attached to the piezoelectric plate 10' is a concave surface of the rigid arcuate element 426. The convex surface of the element 426 is preferably mounted approximately at the center of the long end 40 of the piezoelectric plate 10. The excitation of the piezoelectric plate 10 'is controlled by the applied voltage, depending on the voltage applied. 26 'in the y direction or-
Move in y direction. The force exerted by the spacer 26 'on the element 426 is such that the movement of the spacer 26'
Cause the movement of 6.

The force exerted on the piezoelectric plate 10 by the element 426 causes the piezoelectric plate 10 to rotate in the θ direction or the −θ direction. Arc-shaped element 427 similar to element 426
Moves the spacer 26 "on the piezoelectric plate 10" and the piezoelectric plate 1 as described above for the element 426.
Preferably, it is biased against the long end 42 of the piezoelectric plate 10 to couple the zero rotation. y direction or-
The movement of the spacer 26 "in the y direction is
Is rotated in the -θ direction or the θ direction, respectively, and the direction of rotation is opposite to the direction guided by the piezoelectric plate 10 'having the same movement Dy as the spacer 26'. Moreover, the movement of the spacer 26, which induces a linear movement of the object in the x or -x direction, can be achieved by direct excitation of the piezoelectric plate 10.

Piezoelectric plates 10, 10 'and 10 "
Are preferably electrically connected to correlate the movement of spacers 26, 26 'and 26 "attached to each piezoelectric plate 10, 10' and 10", respectively. The overall movement of the spacer 26, and the resulting movement of the read / write head 374, consists of a superposition of the movements produced individually by each of the piezoelectric plates 10, 10 'and 10 ". It will be appreciated by those skilled in the art that the present invention is not limited to what has been particularly shown and described herein, but rather the scope of the invention is to be determined solely by the appended claims. is there.

Using the apparatus shown in FIG. 43 and described above in connection with the electrification mode described above, compared to a disk drive that does not use such an arrangement, reads out. The write / write head 374 can be provided with an extended range of angles and linear movements, and improves the ability to finely adjust the movement of the read / write head over its entire movement range. be able to. Excitation of the piezoelectric plates 10, 10 'and 10 "can achieve a wide variation in the profile of movement for the read / write head 374.

[0168]

As is apparent from the above description, according to the present invention, it is possible to provide a micromotor having higher speed, higher driving force and smaller minimum step size than the conventional micromotor.

[Brief description of the drawings]

FIG. 1 shows a schematic diagram of a piezoelectric plate useful in a motor according to a preferred embodiment of the present invention.

FIG. 2 shows a first excitation form of the element (A) according to a preferred embodiment of the present invention.

FIG. 3 shows the mode diagram of FIG. 2;

FIG. 4 shows a first excitation configuration of the element of (A) according to a preferred embodiment of the present invention.

FIG. 5 shows the mode diagram of FIG.

FIG. 6 shows the resonance curves of two closely located resonance modes of the element of FIG. 1 according to a preferred embodiment of the present invention.

FIG. 7 illustrates a bimorph-like movement of a piezoelectric element useful in a motor according to a preferred embodiment of the present invention.

8 when applied to the electrodes of the element shown in FIG.
Fig. 4 shows a voltage pulse causing a controlled movement of an object contacting the element.

FIG. 9 is a block diagram of a micromotor that achieves controlled movement according to a preferred embodiment of the present invention.

FIG. 10 is a perspective view of a tandem piezoelectric plate useful in a motor according to a preferred embodiment of the present invention.

FIG. 11 is a perspective view of a tandem / parallel piezoelectric plate useful in a motor according to a preferred embodiment of the present invention.

FIG. 12 shows a perspective view of a piezoelectric plate adapted for xy movement according to a preferred embodiment of the present invention.

FIG. 13 shows a perspective view of two piezoelectric plates adapted for xy movement according to a preferred embodiment of the present invention.

14 is a perspective view of an xy table using the embodiment of FIG.

FIG. 15 illustrates the use of a piezoelectric plate to rotate a cylinder or sphere according to a preferred embodiment of the present invention.

FIG. 16 illustrates another electrode configuration for a piezoelectric plate according to a preferred embodiment of the present invention.

FIG. 17 shows an electrode shape suitable for applying a preloading force of a piezoelectric plate to a driven object according to a preferred embodiment of the present invention.

FIG. 18 shows an electrode shape suitable for applying a preloading force of a piezoelectric plate to a driven object according to a preferred embodiment of the present invention.

FIG. 19 shows an electrode shape suitable for applying a preloading force of a piezoelectric plate to a driven object according to a preferred embodiment of the present invention.

FIG. 20 illustrates another method of mounting a piezoelectric plate according to a preferred embodiment of the present invention.

FIG. 21 shows an application of the mounting principle of FIG. 20 for mounting two piezoelectric plates according to a preferred embodiment of the present invention.

FIG. 22 illustrates another embodiment of using a ceramic motor for a stage of a CD reader according to a preferred embodiment of the present invention.

FIG. 23 illustrates another embodiment in which a ceramic motor is used for a stage of a CD reader according to a preferred embodiment of the present invention.

FIG. 24 shows another embodiment in which a ceramic motor is used for a stage of a CD reader according to a preferred embodiment of the present invention.

FIG. 25 is a block diagram of a piezoelectric micromotor manufactured and operated according to a further preferred embodiment of the present invention.

FIG. 26 is a schematic diagram of the micromotor of FIG. 25 showing a preferred xy resonance mode of the piezoelectric plate of the micromotor.

FIG. 27 according to one preferred embodiment of the present invention.
FIG. 4 is a schematic diagram of a pulse excitation signal for driving a piezoelectric plate of the micromotor of FIG.

FIG. 28 is a schematic diagram of a piezoelectric micromotor driven with different x and y excitation amplitudes.

FIG. 29 is a schematic view of another mounting state of the ceramic plate of the piezoelectric micromotor of FIG. 25;

FIG. 30 is a schematic view of still another mounted state of the ceramic plate of the piezoelectric micromotor of FIG. 25.

FIG. 31 is a schematic diagram illustrating a preferred state of operatively coupling the micromotor of FIGS. 25, 26, and 28-30 to an object.

FIG. 32 shows a schematic diagram of a piezoelectric micromotor utilizing a suppression member to suppress unwanted resonance modes according to a preferred embodiment of the present invention.

FIG. 33 shows an exaggerated oscillatory motion of the micromotor of FIG. 32.

FIG. 34 shows a schematic diagram of a piezoelectric micromotor utilizing a rigid arm to provide increased power and smoother motion according to a preferred embodiment of the present invention.

FIG. 35 quantitatively shows the relative movement of two spacers preferably utilized by the micromotor of FIG. 34 for a selected excitation state.

FIG. 36 is a schematic diagram of another micromotor adapted to provide a symmetrical movement parallel to the short side of the piezoelectric plate according to a preferred embodiment of the present invention.

FIG. 37 is a schematic diagram of yet another micromotor adapted to provide a symmetrical movement parallel to a short side of a piezoelectric plate according to a preferred embodiment of the present invention.

FIG. 38 shows a schematic block diagram of a disk drive according to a preferred embodiment of the present invention that uses a piezoelectric micromotor to move the read / write head.

FIG. 39 is a schematic diagram showing another form of the read / write arm of the disk drive of FIG. 38 according to a preferred embodiment of the present invention.

FIG. 40 is a schematic diagram showing another form of the read / write arm of the disk drive of FIG. 38 according to a preferred embodiment of the present invention;

FIG. 41 is a schematic diagram illustrating another form of the read / write arm of the disk drive of FIG. 38 according to a preferred embodiment of the present invention.

FIG. 42 is a schematic diagram of a dual disk drive according to a preferred embodiment of the present invention.

FIG. 43 is a schematic of a three piezo plate arrangement adapted to provide increased rotational and linear displacement ranges while allowing good tuning of read / write head movement, according to a preferred embodiment of the present invention. FIG.

[Explanation of symbols]

10: piezoelectric plate, 14, 16, 18, 20 ... electrodes,
26 ... spacer.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-52-29192 (JP, A) JP-A-60-176471 (JP, A) JP-A-5-3688 (JP, A) JP-A-2- 142367 (JP, A) JP-A-5-49274 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H02N 2/00 H01L 41/09

Claims (28)

(57) [Claims] A first and a second long side, a first and a second short side,
A first surface having a front surface and a back surface surrounded by long sides and short sides, a plurality of electrodes connected to the front surface, and a counter electrode connected to the back surface;
Piezoelectric plate, first and second long sides, first and second short sides, front and back surfaces surrounded by long and short sides, a plurality of electrodes connected to the front surface, and opposing electrodes connected to the back surface A first spacer attached to the first long side at one end near the first short side of the first piezoelectric plate and engaged with a surface of the object; and a first short plate of the second piezoelectric plate. A second spacer attached to the first long side at one end near the side and engaging the surface of the object; an elastic force source applied to a part of each piezoelectric plate to press each spacer against the surface of the object; A voltage source for applying an excitation voltage to at least some of the plurality of electrodes; a first short side of the first piezoelectric plate is a first short side of the second piezoelectric plate;
Characterized by being substantially parallel and close to the short side,
A piezoelectric micromotor that gives motion to an object. 2. The micromotor according to claim 1, wherein the elastic force source is applied to at least a part of the second long side. 3. The micro-electrode according to claim 2, wherein the elastic force source is applied to a point on a long side of the piezoelectric plate, the point having a motion amplitude perpendicular to the long side surface being substantially zero. motor. 4. The micromotor according to claim 1, wherein the voltage source applies an AC excitation voltage to at least some of the electrodes. 5. An electrode comprising: a plurality of electrodes on a front surface of each piezoelectric plate; and at least one electrode on a back surface of each piezoelectric plate.
The micromotor according to any one of claims 1 to 4, comprising one electrode. 6. The plurality of electrodes on the front surface comprise two diagonally arranged four electrodes, and the voltage source applies an AC excitation voltage to at least some of the plurality of electrodes. A micromotor according to claim 5. 7. The micromotor according to claim 5, wherein an excitation voltage having the same polarity is applied to two electrodes arranged in one diagonal direction among the four electrodes of each piezoelectric plate. 8. A first voltage applied to two electrodes arranged in one diagonal direction among four electrodes of each piezoelectric plate.
The micromotor according to claim 6, wherein the excitation voltage and the second excitation voltage applied to the other two electrodes arranged in the diagonal directions have opposite polarities. 9. Each of the first and second piezoelectric plates has at least one additional electrode connected to at least one long side, and the voltage source applies an excitation voltage to at least some of the additional electrodes. A micromotor according to claim 1. 10. The method according to claim 1, wherein the at least one additional electrode is a first electrode.
The micromotor according to claim 9, wherein the micromotor is provided on the first long side near the short side. 11. The micromotor according to claim 10, wherein another additional electrode is provided on the second long side at a position close to the second short side. 12. The micromotor according to claim 9, wherein the voltage source applies an excitation voltage to an additional electrode, thereby increasing the movement of the spacer in a direction substantially perpendicular to the surface of the object. 13. Each of the first and second piezoelectric plates has an additional electrode mounted on a first long side at a position near the first short side, and the voltage source is an additional electrode of the first piezoelectric plate. 9. The micromotor according to claim 8, wherein the first excitation voltage is applied to an electrode, and the second excitation voltage is applied to an additional electrode of a second piezoelectric plate. 14. The first and second piezoelectric plates are elastically supported at points on each of the long sides where a motion amplitude perpendicular to a plane of the long side is substantially zero. The micromotor according to any one of claims 1 to 8 or 9 to 13. 15. The micromotor according to claim 1, wherein the elastic force source is adjustable. 16. A method according to claim 1, wherein a plurality of first piezoelectric plates and a plurality of second piezoelectric plates are provided, and a spacer of each piezoelectric plate elastically presses an object. The micromotor according to any one of the above. 17. The apparatus of claim 1, further comprising a reverse support device engaging a surface opposite the surface of the object engaging the spacer to provide a reaction to the force applied to the object by each spacer. A micromotor according to claim 8 or claim 9. 18. The device of claim 17, wherein the reverse support device comprises a piezoelectric bearing having electrodes mounted on at least one flat surface, and wherein the voltage source applies a voltage to at least some of the electrodes of the piezoelectric bearing. Micro motor. 19. The first and second long sides, the first and second short sides,
A piezoelectric plate having a front surface and a back surface surrounded by a long side and a short side, a plurality of electrodes connected to the front surface, and a counter electrode connected to the back surface; A spacer that is attached to the second short side of the piezoelectric plate and presses the spacer against the surface of the object; and a power source that excites at least some of the electrodes. Is equal to an integral multiple of half the wavelength of the frequency at which the piezoelectric plate vibrates in the desired resonance mode,
A micromotor that moves an object. 20. First and second long sides, first and second short sides, front and back surfaces surrounded by long and short sides, a plurality of electrodes connected to the front surface, and opposing surfaces connected to the back surface. A piezoelectric plate having electrodes; a first spacer attached to the center of the first short side of the piezoelectric plate and pressed against an object; one end attached to the second short side of the piezoelectric plate and the other end attached to the second spacer A first and second spacer having parallel surfaces adjacent to each other and biased against the object to move the object. 21. First and second long sides, first and second short sides, front and back faces surrounded by long and short sides, a plurality of electrodes connected to the front face, and opposing faces connected to the back face. A first piezoelectric plate having electrodes, a first and a second long side, a first and a second short side, a front surface and a back surface surrounded by the long and short sides, and a plurality of electrodes and a back surface connected to the front surface. A second piezoelectric plate having a connected counter electrode, a spacer attached to a first short side of each of the first and second piezoelectric plates and engaging a surface of an object, a first length of the first piezoelectric plate; At least one fixed support engaging the side, and at least one elastic support engaging the second long side of the first piezoelectric plate; and at least one engaging the first long side of the second piezoelectric plate. A resilient support, and a small number of engagement with the second long side of the second piezoelectric plate. At least one fixed support, the first piezoelectric plate and the second piezoelectric plate are arranged so as to face in parallel with each other, and the long sides of the piezoelectric plate are arranged in parallel with each other. The long side is the first of the second piezoelectric plate
Micromotor adjacent to the long side. 22. Each of said supports is a point on a long side of each of the first and second piezoelectric plates, and a point at which a motion amplitude perpendicular to a plane of the long side is substantially zero. 22. The micromotor according to claim 21, wherein each support is slidable in a direction parallel to the long side. 23. First and second long sides, first and second short sides, front and back faces surrounded by long and short sides, a plurality of electrodes connected to the front faces, and opposing faces connected to the back faces. A piezoelectric plate having electrodes; and a plurality of elastic members for applying an elastic force to the piezoelectric plate at a point on a long side of the piezoelectric plate, wherein a motion amplitude perpendicular to a plane of the long side is substantially zero. Micromotor consisting of elements. 24. A first piezoelectric plate rotatable about a first axis fixed to a base and having two long sides and two short sides, and attached to one of the sides of the first piezoelectric plate. A first spacer engaging a surface of the object, a second piezoelectric plate pivotable about a second axis and having two long sides and two short sides, and one of the second piezoelectric plates. A micromotor for moving an object, comprising a second spacer attached to a side, the second spacer being biased against a side of the first piezoelectric plate. 25. The micromotor according to claim 24, wherein the second spacer is urged against a long side of the first piezoelectric plate. 26. A rigid arcuate element located between the spacer and a long side of the first piezoelectric plate, the arcuate element coupling movement of the spacer and movement of the first piezoelectric plate. 26. The micromotor according to 24 or 25. 27. A third piezoelectric plate rotatable about an axis and having two long sides and two short sides, and a spacer attached to any side of the third piezoelectric plate. 3. The spacer of the third piezoelectric plate urges a side of the first piezoelectric plate that is opposite to a side of the second piezoelectric plate that is urged by the spacer. 4.
27. The micromotor according to 4, 25 or 26. 28. The micromotor according to claim 1, wherein the spacer is made of ceramic.