JP2000040313A - Disk drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a high speed, high driving power and min. step size by providing the second end of an arm with a piezoelectric plate and elastically energizing the side of this piezoelectric plate or its extended portion to a rigid element. SOLUTION: Four electrodes 14, 16, 18 and 20 are plated on the surface of piezoelectric ceramics to form checker patterns consisting of a rectangular shape covering substantially 1/4 of the first surface. The surface on the opposite side of the piezoelectric ceramic is covered with one electrode over the entire part. The electrodes 14 and 18 are excited by a position DC voltage and the electrodes 16 and 20 are excited by a negative DC voltage base on the electrode on the second surface of the piezoelectric ceramic 10. The piezoelectric plate 10 has many resonance modes and the movement thereof is prohibited by a pair of fixed supporting bodies 32 and 34 and two supporting bodies 36 and 38 with springs, by which the wear is reduced and the piezoelectric plate is protected against impact.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a micromotor,
Specifically, the present invention relates 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 edges of the plate, and these pads are pressed against the driven object by a spring mechanism that presses the other longitudinal edge.

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 disk drive with 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 consists of a thin rectangular piezoelectric 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 attached to the center of the short edge of the piezoelectric ceramic,
It is pressed against the object. When at least some of the electrodes are energized, movement of either the piezoelectric ceramic or the object occurs along the length of the edge of the piezoelectric ceramic, as described below.

In a first embodiment of the present invention,
The dimensions of the large face of the rectangle are selected so that the piezoceramics have different modes but resonances located close to x and y (the size of the large face of the piezoceramic rectangle). Is preferred. Preferably, the resonances have overlapping response curves.

[0008] Excitation of the piezoceramic is accomplished by applying an AC voltage at a frequency where 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 present invention,
Excitation is a non-resonant asymmetric pulse voltage to some of the 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 present invention,
It is switched between a resonant AC excitation for relatively large steps and a preferably rectangular pulse excitation when small steps are required.

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 piezoceramic and extending along the length of the large rectangular surface of the ceramic.

A second preferred electrode configuration provides four electrodes that cover the four quadrants of the large face of the piezoelectric ceramic. If different excitation modes (AC and pulse) and excitation shapes result in a larger or smaller minimum step size for the motion caused by the motor, one, two or three of these electrodes will be excited.

Another feature of the present invention involves the use of a plurality of stacked piezoelectric ceramics having the same resonance frequency, which are preferably formed of different piezoelectric materials,
One of them 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 yet another feature of the invention, one end of the arm is attached to a short edge of the piezoelectric ceramic opposite the spacer bearing edge. 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 utilizing the motion and force across the piezoelectric ceramic to move the Smooth movement of the object being biased.

Another feature of the present invention involves the use of a resilient element that applies a resilient force to the longitudinal edge of the piezoelectric plate at a point having substantially zero motion perpendicular to the longitudinal edge. Such elements are used to impart symmetrical movement to the object in both directions parallel to the short edge 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 invention, the micromotor for moving the object comprises a long edge and a short edge, the first and second surfaces, the electrodes mounted on the first and second surfaces, the first and second surfaces. An edge, preferably a short edge, preferably at the center thereof, at least one rectangular piezoelectric plate having a ceramic spacer pressed against the object, and a second edge opposite the first edge, preferably at the center thereof; It consists of an elastic force source that applies a force and presses the ceramic spacer against the object, and a power source that excites 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. I have.

In a preferred embodiment of the invention, the electrodes in the quadrant along one longitudinal edge of the first face of the plate are applied with a unipolar symmetric pulse voltage having a first polarity, The electrodes in the quadrant along the other longitudinal edge of the first surface are subjected to a unipolar symmetric pulse voltage of 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. Is applied with a unipolar symmetric pulse voltage having the opposite polarity.

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

In a preferred embodiment of the present invention, the micromotor includes a plurality of the piezoelectric plates, and the ceramic spacer of each plate is elastically pressed against an 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 voltage source applies voltages to at least one of the plates out of phase with each other.

Further, in a preferred embodiment of the present invention, there are provided longitudinal and short edges, first and second surfaces, electrodes mounted on the first and second surfaces, and at least some of the electrodes. At least one rectangular piezoelectric plate whose electrodes are symmetric and applied with a unipolar pulsed excitation voltage, and an elastic force for elastically biasing one edge or one or more edge extensions to the object. A source and a micromotor for moving an object comprising the same are provided.

Further, in a preferred embodiment of the present invention, there is provided at least one rectangular piezoelectric plate having longitudinal and short edges, first and second surfaces, electrodes mounted on the first and second surfaces, A source of elastic force for elastically biasing one edge, or one or more extensions of the edge, against an object, and applying a symmetric and monopolar pulsed or AC excitation voltage to at least some of the electrodes. A micromotor for moving an object comprising a selectively applied voltage source and an object is provided.

Further, in a preferred embodiment of the present invention, there are electrodes attached to the long and short edges, the first and second surfaces, and the first and second surfaces, at least some of the electrodes. Moving an object comprising a plurality of rectangular piezoelectric plates to be excited and a source of resilient force for resiliently biasing one or more of the edges of the plurality of plates against the object. A micromotor is provided.

Further, in a preferred embodiment of the present invention, there are longitudinal and short edges, first and second surfaces, and electrodes mounted on the first and second surfaces, wherein at least one of the electrodes has a voltage. , Causing a force towards only one edge of the plate and at least one of the other electrodes
A micromotor is provided for moving an object consisting of at least one rectangular piezoelectric plate, one of which is excited with a voltage to cause movement of at least a portion of the edge having an element along the edge.

Further, in a preferred embodiment of the present invention, at least one rectangular piezoelectric plate having longitudinal and short edges, first and second surfaces, and electrodes mounted on the first and second surfaces, A micromotor for moving an object, comprising: a power source for applying a voltage of several electrodes to establish a desired resonance mode of a piezoelectric plate; and mode suppression means for suppressing a resonance mode other than the desired resonance mode, is provided. I have.

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

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

Further, in a preferred embodiment of the present invention, there are electrodes attached to the long and short edges, the first and second surfaces, the first and second surfaces, at least some of the electrodes. A micromotor for moving an object which is excited and has 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 hole. Is 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 edges of the piezoelectric plate, preferably in the center of the short edge. This allows the available space perpendicular to the engagement surface to be such that the long edge of the seat is substantially perpendicular to the engagement surface, since an optimal drive movement is created at the short edge of the ceramic plate. In systems where the available surface perpendicular to the engagement surface is limited, according to a preferred embodiment of the present invention, an alternative ceramic micromotor is provided. Here, the movement of the short edge of the piezoceramic plate is to move an object juxtaposed with the long edge of the plate using spacers attached to the long edge of the plate near the corners of the long and short edges. Used for

According to this feature of the invention, the spacer moves at a short edge 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 edges, first and second short edges, front and back surfaces, and a first plate The first short edge is juxtaposed substantially parallel to the first short edge of the second plate, each plate having electrodes mounted on the front and back surfaces, each plate being proximate to the first short edge. An elastic force source attached to the first longitudinal edge at one end of the plate and engaging the surface of the object and applied to a portion of each plate to press the ceramic spacer against the surface of the object. Are provided.

[0038] In a preferred embodiment of the invention, the elastic source is applied to at least a part of the second longitudinal edge. Additionally or alternatively, the source of elastic force is applied to a point on the piezoelectric plate, and the amplitude of motion perpendicular to the plane is substantially zero.

Furthermore, in a preferred embodiment of the present invention, the first and second substantially rectangular first and second
Piezoelectric plates, each plate having two longitudinal edges and two
At least one short edge, a front surface and a back surface, the faces of adjacent plates are parallel and opposite each other, and the longitudinal edges of adjacent plates are parallel and engage at least one first longitudinal edge of the first plate. One fixed support, at least one elastic support engaging a second longitudinal edge of the first plate, at least one elastic support engaging a first longitudinal edge of the second plate, and a second elastic support of the second plate.
A piezoelectric micromotor for providing motion to an object is provided, wherein the piezoelectric micromotor comprises at least one fixed support engaging a longitudinal edge, the first longitudinal edge of the first plate being adjacent to the first longitudinal edge of the second plate. Have been.

Preferably, each support engages the respective longitudinal edge at a point of substantially zero movement in a direction perpendicular to the longitudinal edge and is slidable in a direction substantially parallel to the longitudinal edge.

Further, in a preferred embodiment of the present invention, the long and short edges, the first and second surfaces, the electrodes mounted on the first and second surfaces, and the substantially zero in the direction perpendicular to the long edges. At least one rectangular piezoelectric plate having an elastic element that applies elastic force to each of the longitudinal edges at two points of movement, and at least some electrodes in two modes, namely, a first parallel edge of the short edge. Means for moving an object comprising: a first mode for providing short-term motion in a direction; and a power source for selectively exciting in a second mode for providing motion in a second direction opposite to the first direction. A micromotor is provided.

[0042] In another preferred embodiment of the present invention, the micromotor further comprises a structural assembly adapted to provide 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 include 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 quadrants located on the diagonal line of each plate.

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

In one preferred embodiment of the present invention,
The power source applies to at least some of the electrodes a pulsed excitation voltage consisting of AC excitation voltage pulses separated at regular intervals from a DC voltage having an absolute value greater than the amplitude of the AC 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,
The first and second rectangular piezoelectric plates have at least one additional electrode connected to at least one longitudinal edge, and the voltage source applies at least some additional electrodes. Preferably, said at least one additional electrode is a first
Including an electrode with a first long edge near the short edge.
More preferably, said at least one additional electrode comprises an electrode at a second longitudinal edge near a second shorter edge.

[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 the electrode in the quadrant on the front surface 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 where the amplitude of the motion 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 an object. I have.

In a preferred embodiment of the invention, the micromotor further engages the 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 rotatable about an axis and which are spaced apart from the axis by a certain distance on both sides, read / write heads attached to the first end, A disk drive is provided comprising a rigid arm at two ends and at least one piezoelectric plate micromotor resiliently biased against a rigid element.

In a preferred embodiment of the present invention, the 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,
A disk drive having first and second ends spaced apart from the axis on both sides at a fixed distance, a read / write head mounted on the first end, and a piezoelectric plate mounted on the second end and movable with the arm. Provided.

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 edges and two short edges, and two long edges and two short edges. A micromotor for moving an object is provided, comprising an edge, a second rectangular piezoelectric plate having a ceramic spacer attached to the edge, the spacer being biased against an edge of the first piezoelectric plate. .

Preferably, the spacer attached to the second piezoelectric plate is urged against a longitudinal edge of the first piezoelectric plate.

In some preferred embodiments of the present invention, the micromotor is further located between a spacer of the second piezoelectric plate and a longitudinal edge of the first piezoelectric plate against which the spacer is biased. Consists of a rigid 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 ceramic used in a motor according to a preferred embodiment of the present invention. On the surface of the piezoelectric ceramic (hereinafter referred to as the "first surface"), four electrodes 14, 16, 18 and 20 are plated or otherwise stuck, whereby Has a checker pattern consisting of a rectangle that substantially covers 1/4 of the first surface. The opposite surface of the piezoelectric ceramic (hereinafter referred to as “second surface”)
Preferably, one electrode (not shown) substantially covers the whole. The diagonally arranged electrodes (14 and 20; 16 and 18) are electrically connected, preferably by wires 22 and 24 located near the junction of the four electrodes. 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 ceramic 10, preferably at the center of the side.

The piezoelectric ceramic 10 has a number of resonance modes. In particular, the piezoelectric ceramic 1
The dimension of 0 indicates that the resonance modes in the Dx and Dy directions are closely spaced (excitation curve).
The dimensions are chosen such that s) overlaps. In particular, the preferred resonance according to the present invention is a 図 mode resonance in the Dy direction, as shown in FIGS.
The direction is 11/2 mode resonance. However, other resonance modes can be used depending on the dimensions of the ceramic 10.

When the piezoelectric ceramic 10 is excited at a frequency in the band indicated as ω0 in FIG.
Both x and Dy resonant modes are excited. FIG.
FIG. 2 shows an example (one configuration) of applying a voltage to a given electrode, thereby exciting two resonance modes.
In this example, voltage is applied to electrodes 16 and 18 and electrodes 14 and 20 are left floating (or less preferably grounded), but the amplitude of that mode is shown in FIG. . The excitation in this example causes Dx to be negative when Dy is positive, so that when the movement of the piezoelectric ceramic 10 is blocked, the body 30 pressed against the piezoelectric ceramic 10 moves to the left. Become.
Although the surface of the body 30 is depicted as curved, like the surface of a cylinder to be rotated, 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 a preferred embodiment of the present invention, the piezoelectric ceramic 10 comprises a fixed pair of supports 32 and 34.
And two spring loaded supports 36 and 38 prevent movement. The supports 32 to 38 are in contact with the piezoelectric ceramic 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 way reduces the effect of wear and protects the piezoelectric ceramic from a certain degree of impact (a degree of shock pr
otection).

The spring-loaded support 44 is preferably pressed against the center of the second short side 43 of the piezoelectric ceramic 10 opposite the short side 28. The support 44 is made of ceramic 26
Pressure between the body and the body 30, whereby the movement of the ceramic 26 is transmitted to the body 30. It should be noted that the spring-loaded support 44 has a response time sufficiently longer than one period of the frequency at which the piezoelectric ceramic 10 is excited. Thus, when the ceramic 26 is moving in the opposite direction of movement imparted to the body 30, the surface of the ceramic 26 that is pressed against the body 30 actually leaves the body for only a portion 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 of about 60. a Shore A hardness of about 60), preferably 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 ceramic used. In a preferred embodiment of the invention, a spherical or hemispherical rigid element is arranged between the spring element and the ceramic.

In a preferred embodiment of the present invention, the dimensions of the piezoelectric ceramic 10 are measured by Morgan Matlock (Morg).
30mm x 7.7m with thickness between 2mm and 5mm using PZT piezoelectric material manufactured by An Matroc Inc.)
The size of m. For this example, the desired speed, body 3
Depending on the weight of zero (and / or the pressure of the spring 44) and the required power, 30-500 volts alternating current can be used to excite the piezoelectric ceramic 10. Such devices operate at frequencies in the range of 20-100 kHz, have a minimum step size in the range of 10 nanometers (nm), and have a minimum step size of about 15-350 mm / sec.
(Or more). These are only nominal ranges and will vary depending on the material used for the piezoelectric ceramic 10, the dimensions, the selected resonance mode, 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 ceramic 10 urged against the main body 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, short side 28 directly engages body 30. This increase in force is the result of the resonance mode energy generated in the piezoceramic 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 the 2 /
The use of spacers of almost equal length to 2, 3/2 or 4/2 wavelengths. 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
Ceramic spacers having a length of 55 mm have been found to be suitable.

In the embodiment described above in connection with FIGS. 1 to 6, the piezoelectric ceramic 10 shown in FIG.
Are excited by an AC voltage having a frequency close to the resonance of the piezoelectric ceramic. In the method depicted in FIGS. 7 and 8,
Pulsed unipolar voltage
Excited by In this pulsed excitation embodiment according to the invention, the electrodes 14, 16, 18 and 2
The 0s are not connected in a fixed way as in the embodiment of FIG. 1, but are connected in different ways depending on the required minimum step, as explained below.

The principle of operation of the pulse method is shown in FIG. In this figure, the second
With reference to the electrodes on the surface, electrodes 14 and 18 are excited by a positive DC voltage and electrodes 16 and 20 are excited by a negative DC voltage. Under this excitation, the left side 10 of the piezoceramic 10 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 inventors have found that when a voltage pulse as shown in FIG. 1 is applied to the electrode, the body does not return to its starting position by means of 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 piezoceramic 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, and for larger masses, the minimum step is larger due to increased inertia. Become. This mode is not generally used for large movements, but is useful for the final placement of objects to be moved. Reversing the polarity of the excitation, or increasing the rise time and decreasing the fall time, will result in movement in the opposite direction. The operation of the body in this mode is not well understood, but extremely small minimum steps can be achieved.

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

In an alternative embodiment in which the motor operates in a pulsed fashion, the same voltage is applied to the electrodes 14 and 16 and
Opposite polarity voltages are applied to electrodes 18 and 20 (or grounded or left floating). 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 a preferred embodiment of the motor according to the invention, the piezoceramic 10 is first described with reference to FIGS. 1 to 6 so as to produce a high-speed movement near the target position. , 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 illustrated 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
Microcontroller 52 indicating the position of body 30 and
A position signal is received from a position indicator (or position detector) 68 that provides feedback to the controller. 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 movement required, based on predetermined optimization criteria, whether the AC or pulse mode is appropriate, and the direction in which most of the body moves. Determines which direction it is. A plurality of suitable signals are either AC or pulsed (or no voltage or ground voltage) to each electrode so that the piezoceramic 10 operates in a suitable excitation configuration as described above. ) Is generated and applied to the switch / modulator circuit. The remaining distance to be moved is reduced to below a suitable level, and the microcontroller 52 returns to FIG.
And switch to the high resolution low speed mode utilizing appropriate pulse excitation as described above with reference to FIG. Some variation in the excitation mode may be made as appropriate when high positional accuracy is desired. When the body 30 reaches the target position, the excitation of the plurality of electrodes is terminated.

The inductor 66 is used to tune the electric resonance of the piezoelectric ceramic 10 and the wiring connected thereto to the same frequency as the mechanical resonance of the piezoelectric ceramic 10.
Is used. The electric circuit is composed of the first piezoelectric ceramic 10.
And the majority of the capacitance formed by the plurality of electrodes on the second surface, so that this capacitance may be "set out of tune" and improve the efficiency of the system, for example, by using inductor 66. It is appropriate to add such an inductor.

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 constraint menber is used to increase the performance of the micromotor by suppressing resonance modes other than the desired resonance mode. FIG. 32 shows a form in which two restraining members are used,
FIG. 33 shows a form, similar to FIG. 32, showing the ceramic 10 for the desired mode with the departure from actual dimensions highlighted. The restraining members 300 and 302 tightly attached to the outline of the piezoelectric ceramic 10 can be made of a thread or a wire, and can be bonded to the piezoelectric ceramic. The members 300.302 can also include plastic or metal moldings. Member 30
0.302 is preferably located at a point where the dimensional change is zero in the X direction for the desired mode of operation, ie, at approximately 1/6 and approximately 5/6 of the length of the ceramic 10. Other modes have dimensional changes at one or both of their locations and are thereby suppressed. In such a configuration, the motion width of the spacer 26 (motion amplitu)
de) can be increased by reaching 30% compared to the movement width obtained with the same input power in a micromotor without a restraining member. Also, only one of the restriction members 300 or 302 is used.

In a preferred embodiment of the present invention, as shown in FIG. 34, in order to increase the output of the micromotor and to make the operation of the main body pressed by the spacer smooth, the fixed arm 310 has a spacer bearing end ( bearing ed
ge) to the short-circuited end of the piezoelectric ceramic 10 (short edg).
e) is attached. The arm 310 is preferably mounted substantially parallel to the surface of the piezoelectric ceramic 10, and one end of the arm 310 is mounted via a vertical member 314 to the short-circuit end 43 of the ceramic 10. The spacer 312 that is pressed and attached to the main body 30 is attached to the arm 3 near the end of the ceramic 10 to which the spacer 26 is attached.
10 is attached to the other end.

There are many other preferred embodiments of the embodiment of FIG. In one such form, the spacer 312 is preferably ceramic and the vertical member 312
14 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 side of the piezoelectric ceramic 10. In another form, the vertical member 314 is ceramic. In the embodiment described above, the vertical member 3
14 can be attached along the entire short-circuit end 43, or can be attached only to the central portion of the short-circuit end 43 by, for example, a ceramic spacer.

In the form shown in FIG. 3 or FIG. 5, the excitation (excita
One use of the form described above in connection with
As shown in FIG. 7, the out-of-phase operation (180 ° phase difference) of the spacer 312 with respect to the spacer 26 is performed. As a result, the force acting on the body 30 is doubled and the movement of the body 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 ceramics increase the output of the motor,
And can be configured to reduce the variability that exists between different devices. One such configuration, shown in FIG. 10, comprises two piezoelectric ceramics 10, 10 'in a comb configuration. That is, the piezoelectric ceramics 10 and 1
Two piezoelectric ceramics 10, 10 'are mounted in a comb in the direction of motion induced by 0'. The two piezoceramics are connected to the control system 50 shown in FIG.
Or a separate control system. For clarity, the control system and electrical connections are not shown in FIG.

As shown in FIG.
The spacer unit 74 located in the middle between 0 and 10 '
The piezoelectric ceramic is supported and separated. Four spring-biased side supports 76 and two spring-biased end supports 78 support the piezoelectric ceramic pairs in the same manner as described above in connection with the embodiment of FIG. In practice, the piezoceramics 10, 10 'preferably comprise a spacer unit 74 and a spring-biased support 7.
The 6,78 elongation restricts movement perpendicular to the surface of the piezoelectric ceramic. Such a configuration is shown in FIG.

FIG. 11 shows six piezoelectric ceramics formed in a comb / parallel configuration of two units and three units. Due to the limitations shown, the spring-loaded support and the pressing spacer unit 7 for the piezoelectric ceramics
Although the mechanism 4 is not shown, a preferred support mechanism is that shown in FIG. Another form, 2 ×
A four comb / parallel configuration is also beneficial.

In the preferred embodiment of the motor according to the invention, the piezoceramics 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 ceramics are made of a relatively hard material, such as PZT-8 (manufactured by Morgan Matroc Inc.), and the one or more piezoelectric ceramics are Is PZT-5H (Morgan Mat
(manufactured by roc Inc.). The above two types of materials have the same x, y dimensions and the same resonance, and can be physically shaped so that the resonance frequency is obtained by adjusting the thickness of the individual piezoceramics. it can. Also, both materials can be used at the same thickness. In such a configuration, a broader of the above soft material
Q will assume that both hard and soft materials are fully excite at the same frequency.

When the soft piezoelectric ceramic is charged, the resonance width increases in both Dx and Dy, and the portion (time) during which the ceramic 26 contacts the body is larger than for the hard piezoelectric ceramic. However, due to this property, the driving force acting on the soft piezoelectric ceramic is low, and the operation unevenness is also low.

In a preferred embodiment of the invention, where both types of piezoelectric ceramics are used, as described in the preceding paragraph, hard piezoelectric ceramics have the ability to reduce traction and other inertial forces and are soft. Piezoceramics have the ability to provide a smoother, more accurate operation at smooth stop and start than when only hard piezoceramics are used.

In a preferred embodiment of the present invention, 2
Two types of ceramic are out of phase with each other (180 °
Phase difference). In this case, the two types of ceramics are essentially independent (excitation cycle).
at different parts of the piezoceramic cycle), resulting in minimal friction due to the different behavior of the two types of piezoceramics. 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 piezoceramics 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 90 of the same or different ceramics can be used in a parallel-comb configuration as described above with respect to FIGS.

FIG. 13 shows a second, reminiscently simple, but not compact form, in which two piezoceramics as shown in FIGS.
They are secured together to achieve an X movement at one end and a Y movement at the other end.

An XY table 1 using the configuration of FIG. 13 and configured as a preferred embodiment of the present invention.
00 is shown in simplified form in FIG. The table 100 comprises two piezoelectric ceramics 10 in the configuration of FIG. 13 sandwiched between a fixed base 102 and a top 104, and supports 106, 10
8, 110, 112, 114 and 116, 118 and 120 are identical in shape and function to the supports 32, 34, 36 and 38 of FIGS. Support 10
All of 6 to 120 are provided integrally with the fixing material (not clearly shown), but are not attached to the base 102. However, the fixer and base 10
It is preferable to provide a slider that is allowed to slide in the X direction (indicated by an arrow 122) between the first and second fixing members, and is attached to the fixing 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 ceramics 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 ceramic causes it to move 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, excitation of the lower piezoceramic causes the X motion of the top 104. When the upper piezoelectric ceramic 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 piezoceramics causes the XY movement of the top 104 with respect to the base 102, with respect to the linear motion shown above for the embodiment of FIGS. It has all the advantages of the embodiment. Exciting only one of the piezoceramics results in 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, the two tandem and series arrangements of piezoelectric ceramics of different or identical parts are the same as described above, as in the two tandem arrangement for the linear motion device, with reference to FIGS. Generate usage.

The use of a piezoceramic according to the invention to achieve a rotational movement is shown in FIG.
Two tandem forms of piezoceramic 150 similar to that shown at 0 are applied along cylinder 152 and 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 piezoceramic similar to that shown in FIGS. 1-5, or some of the piezoceramics arranged in an annulus, can be used in place of feature 150.

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, a greater force can be used to push the ceramic against the body 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 ceramic in the present invention.

Further, the present invention is applicable to the case where the rectangular electrode shown in the above-described embodiment is used.
The movement is not perfectly straight, ie, the ceramic 26
It can be seen that due to the rotational nature of the movement, only a portion of the ceramic contacts the body 30 in operation. 14 ', 1
If 6 ', 18' and 20 'are loose 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.

As a preferred embodiment of the present invention, FIG.
6, an arrangement including a plurality of piezoelectric ceramics is used to make the movement of the body 30 symmetrical in the opposite direction along the X 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 has two parallel piezoelectric ceramics 10, oriented in the same direction in the XY plane formed by the X and Y directions shown in FIG.
Has 10 '

As shown in FIG. 36, the piezoelectric ceramic 1
Each of 0, 10 'is a pair of fixed supports 32, 34.
The movement is restricted by the pair of elastic supports 36 and 38. The supports 32-38 attract the ceramics 10, 10 'along the longitudinal corners 40, 42 and 40', 42 'of each ceramic in an attempt to achieve substantially zero displacement along the X axis. I have. Supports 32-38
Is preferably slidable along the Y axis.

The fixed supports 32 and 34 attract the piezoelectric ceramic 10 along the longitudinal corners 40,
On the other hand, since the piezoelectric ceramic 10 'is fixed, the supports 32 and 34 attract the longitudinal corners 42'. The resilient supports 36, 38 attract the piezoelectric ceramic 10 along the longitudinal corners 42, while the resilient supports 36.38, due to the piezoelectric ceramic 10 ', extend along the longitudinal corners 40'. 10 '. With this arrangement, some differences between the X and -X movements caused by one piezoceramic are compensated by another, identical and opposite piezoceramic.

An alternative arrangement for providing symmetrical movement along the X axis is shown 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 in the piezoelectric ceramic 10, especially the ceramic surface. Hinge 3
Holes for 26 and 327 are located along the short edge between the two electrodes, eg, between electrodes 14 and 16, and between electrodes 18 and 20, respectively, at locations where they do not move along the X axis. Preferably it is. In a preferred embodiment of the present invention,
Hinge 326 and 327 are 1/6 and 5/6 the length of ceramic 10 and are spaced from short edge 28, respectively.

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
Numerals 7 and 338 provide an elastic force to the piezoelectric ceramic 10 at about 1/6 of the length of the ceramic.
A similar element provides elasticity at about 5/6 the length of the ceramic 10.

In one typical device, the piezoceramic 10 is made of PZT.4 and has a length of 300 mm, a width of 7 mm, and a thickness of 3 mm. The elastic elements 337 and 338 in this device are silicon cylinders 5 mm long, 2.5.3 mm in diameter and 60.70 Shore hardness. The elastic element 44 has a length of 5 mm and a diameter of 2.5
mm, it is possible to exert a force of about 5 N (Newton) on the short edge 43 of the piezoelectric ceramic 10. FIG. 3 or FIG.
As shown in the figure, when the piezoelectric ceramic is excited with an alternating current of 200 and 300 V and this device is used, 0.1.
A resolution of m and a speed of up to about 400 mm / sec are obtained.

In a preferred embodiment of the present invention, FIG.
Are used. For this embodiment, an additional electrode 150 is applied to the piezoelectric ceramic in addition to the electrodes 14, 16, 18, 20. Electrode 1
50 preferably extends to the same width as the ceramic 10 and is excited by a DC voltage or a harmonic voltage used at another electrode. As a result of such excitation, the ceramic 10 is stretched and pre-loads the motor on the moving object. By using harmonic excitation, this preload is synchronized with respect to the other electrodes, increasing the contact time between 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 piezoceramics) is used,
There is even need. 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, the hole is located at the center of the piezoelectric ceramic 10;
It is formed at 1/6 and 5/6 positions on the center line. 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.

Because of the resonant mode of the ceramic 10 used in the preferred embodiment of the present invention, the ceramic moves only in the longitudinal direction of the hole. In fact, the central hole hardly moves. When the other end of the lever is rotatably attached to the fixed body 160, the ceramic 10 is moved only along its long axis. Thereby, the springs 36 and 38
Can be removed. Further, the spring 44
Pushes one of the levers in the direction the object is moved,
It is replaced by a spring 44 'that biases the motor. Many such springs are used to bias other levers.

A similar principle applies only to mounting two juxtaposed piezoceramic elements 10 and 10 ', as shown in FIG. In this arrangement, the piezoceramics 10 and 10 'are mounted on five levers 162, 164, 166, 168, 170 used for the above-described means. 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 'is separately biased at its lower end by a spring 44.

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 biased by a spring (not shown) to bias the ceramics 10 and 10 'against the moving object. The various width dimensions of the mounting means can of course be technically improved by using this principle in these preferred embodiments.

The main advantage of mounting piezoceramics on the pins described above 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 is filled with about 40% PZT powder (of a material similar to the piezoceramic itself). Such a filling allows the acoustic velocity in the epoxy to be matched to the piezoelectric ceramic.

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 moving object is coated with metal,
Electrodes are in contact with this coating. For this purpose, the coating extends to the side of the ceramic 26. The moving object is made of metal (or having a metal coating), and the contact time can be measured as a short-circuit time between the metal coating of the ceramic 26 and the moving object.

FIGS. 22, 23 and 24 show a case where a ceramic motor is applied to the movement of the stage, and is used as an optical disk reader such as a CD reader. In such an apparatus, a hole 164 is formed in the stage 160, and an optical reader (not shown alone) mounted on the stage 160 detects (and reads) an optical disk.

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 the embodiments described above, the spacer between the ceramic plate and the surface on which the micromotor is mounted is mounted at one of the short edges of the ceramic plate, preferably at the center of the short edge. The longitudinal direction of the plate is perpendicular to the mounting surface. This arrangement is preferred because the optical drive operation is obtained at the short edge 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. Become.
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 optical movement created by the short edge of the ceramic plate is available.

For such an embodiment of the invention, the ceramic spacer is attached to one end of the long edge of the piezoelectric plate and is mounted on a plane parallel to the long edge. Since the spacer so mounted is arranged near the short edge of the ceramic plate, the spacer moves at the short edge in relation to the resonance operation. As a result of this movement of the spacer,
The movement of the surface or micromotor engaging the spacer is obtained. 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 edge 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. 15 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 comprises two piezoceramic plates 212 and 214 mounted in a housing 220 preferably made of aluminum. Housing 220 is preferably pressed against surface 210. The outer short edges of the plates 212 and 214, ie, the right edge of the plate 212 and the left edge of the plate 214 illustrated in FIG. 25, are preferably horizontal, made of a relatively rigid material such as, for example, a ceramic material. Is supported by the support member 222. The inner short edges of the plates 212 and 214, ie, the left edge of the plate 212 and the right edge 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 may be made of the same material as member 226, or
Supported from its bottom by a bottom support member 224, which can be preferably formed of a stiffer material.

According to a preferred embodiment of the present invention, a spacer 216, preferably made of ceramic, is attached to the upper surface of plate 212 at its left end and a similar spacer 28 is attached to the upper surface of plate 214 at its right end. Attached to the part. Spacers 212 and 214
Is functionally fitted and attached to surface 210 when micromotor 200 is pressed against surface 210. In a preferred embodiment according to the present invention, the housing 220 preferably comprises a protective frame 215 formed or coated with a low friction material such as Teflon, the frame 215 comprising spacers 216 and At least partially separated from the area of the mated and attached surface 210 by 218 to prevent unwanted matter, such as debris, from accumulating on the surface 210.

The four electrodes are plated to form a checkerboard-like patterned electrode having a plurality of rectangular shapes or otherwise mounted on the front of each of the piezoceramic plates 212 and 214. Here, each of the plurality of rectangles of the pattern electrode is shown in FIG.
Cover substantially one quarter of the front surface, as described above with reference to the electrodes 14, 16, 18 and 20 at. The back surface of each piezoelectric ceramic 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 electrodes located diagonally are preferably 4
Multiple wires 230 placed near the junction of the two electrodes
Electrically connected by The plurality of electrodes on the back of each ceramic plate are preferably 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 214 and 216
As in the above-described embodiment, it may be formed of relatively soft or relatively hard ceramics. However,
Excitation of the plurality of electrodes on the plate 212 is effected in the same horizontal direction with respect to the surface 210 as described below.
In order to obtain the movement of 6 and 218, it is necessary to invert compared to the excitation of the electrodes on the plate 214.

Piezoelectric ceramic plates 212 and 214
26, which illustrates a plurality of preferred xy resonance modes in FIG. As shown in FIG. 26, the plurality of electrodes on plates 212 and 214 are preferably electrodes 25, which are two groups of electrodes.
4 and an electrode 256. 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. ,
In addition, a voltage is applied in the opposite direction.

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 piezo ceramics 212 and 214
14 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.

Reference is now made to FIG. 27, which schematically illustrates a pulse-shaped excitation signal controlled by microcontroller 244 (FIG. 25) provided to electrodes 254 and 256 according to a preferred embodiment of the present invention. . FIG.
The excitation signal consists of a plurality of pulses of a drive excitation voltage, separated by a predetermined DC voltage interval, which 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 “A”.
And the DC voltage between the pulses is indicated by "B". 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 body mounted by the micromotor. You.

The typical resonance frequencies of the bodies driven by the micromotor, ie, 300H
Frequencies in the order of z 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 a spacer 216 and 2
Depending on whether electrode 254 or 256 is driven, so that 18 moves away from surface 210 between pulses, it is either lower than the lower peak of the drive frequency or the higher drive frequency. Higher than the peak. Thus, the driven body autonomously moves between pulses. This correlation between the pulse rate of the excitation signal and the self-resonance of the matingly mounted body results in a catastrophic between the drive pulse and the response of the body driven 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 invention, additional electrodes 260 are provided on the upper and lower edges of plates 212 and 214. Multiple electrodes 2
60 is preferably excited by the same excitation voltages used to drive the 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. The spacers 216 are slightly angled, as opposed to the substantially circular movement of the plurality of spacers in FIG. 26 schematically illustrated over the plurality of spacers.
This movement of the elliptical shape of 218 and 218 increases the time of contact between the spacers 216 and 218 and the surface 210, and thus a greater driving force between the plurality of spacers and the surface 210. A micromotor 200 having good traction (traction friction) is provided.

Piezoelectric ceramic plates 212 and 214
Reference is now made to FIG.
In addition to horizontal support member 222 and connecting member 226, plates 212 and 214 are under plate 212 and plate 214 and between housing 212
20 (FIG. 25) is supported by the base 266 mounted. 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 265 fixedly mounted to the housing 220, while the other end of each holder 262 is mounted on a plate 212 or 2
14 is rotatably mounted on each pin 264 extending through each hole. Four pins 264 are preferably mounted on plates 212 and 214, and two pins on each plate are mounted at multiple points where the amplitude along the Y axis is substantially zero as described above. Is done. In a preferred embodiment, two holders 262 are mounted on each pin 264, and one holder is mounted on each side of plate 212 or 214. An elastic bottom support member 263 is preferably mounted between the lower end of each holder 262 and the bottom edge 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 configured as shown in FIG.
, Which allows a drive movement of the piezoelectric plates 212 and 214 along the Y-axis.

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 edges 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, a preferred embodiment of the present invention, a counter-bearing device 280, includes a housing 282, which is
It is preferable to fix and connect to the housing 220 via a connector 290. At least one bearing 284 in housing 282 provides for the back of object 278 (ie, micromotor 20) to be applied to the force applied to the front of object 278 by spacers 216 and 218.
0 (the surface that does not engage with 0). 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
12 and 214 include similar piezoelectric ceramics. In this embodiment, the ground electrode (not shown) is
While the other surface of bearing 284 includes two separate electrodes 286 and 288, which cover one-half of that surface. Electrodes 286 and 2
When the AC voltage is applied as described above, the bearings 28 are positioned as shown in FIG.
4 oscillate at the resonance frequency along the y-axis. Bearings 284 are driven in the appropriate direction, e.g., upward, at the y-axis frequency of plates 212 and 214, and spacers 216 and 218
As the spacers gradually descend and the spacers rise, they provide a very effective counter-bearing for the forces exerted by the micromotor 200. 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. There must be. In such a case, the sets of plates are preferably mounted parallel to one another.

In some preferred embodiments of the present invention, piezoceramic 10 is utilized in a disk drive for moving and positioning the 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. The disk drive 350 includes a disk 35 rotatable about an axis 354.
2 and a read / write assembly 360. The read / write assembly 360 includes an arm 370 pivotable about an axis 372 and the piezoceramic 10 used to pivot the arm 370 about the axis 372. The scanning of the disk 352 is performed by moving the arm 370 to the axis 372.
Is achieved by rotating the disk 352 about the axis 354 while rotating about the axis. Disk 3
The reading and writing of the read / write head
4, the head may be any known head mounted at the end of the arm 370.

FIG. 39 is a detailed view of the read / write assembly 360. As shown in FIG.
0 can be of any of the types described above, but can be mounted on a fixed base (not shown) through
It is preferably fixedly mounted to the slidably mounted element via hmounts 385 and 386. The piezoelectric ceramic 10 is elastically urged by the elastic element 44 against the rigid element 380 of the arm 370. The elastic element 44 is preferably pressed against a fixed element in a fixed base (not shown). When excited according to one of the above excitation shapes, the piezoelectric ceramic 10 causes the spacer 26 urged against the rigid element 380 to be in either the x or -x direction depending on the voltage application condition. Moving. The relative movement between the spacer 26 and the arm 370 via the rigid element 380 causes the arm 370 to move
Orbit around. As a result, the read / write head 374
Moves in a direction of either θ or −θ substantially in contact with the radius of the disk 352.

The mounts 385 and 386 extend through the holes in the piezoelectric ceramic 10. 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 show the piezoelectric ceramic 10.
Is different from FIG. 39 in that As shown in FIG. 40, the piezoelectric ceramic 10 can be mounted on a fixed base by a pair of fixing elements 390 and 391. The fastening elements 390 and 391 preferably engage the piezoelectric ceramic 10 at about 1/6 and 5/6 of the length of the ceramic. Piezoceramic 10 is located in guide holes formed in elements 390 and 391 so as to allow movement along the longitudinal axis of ceramic 10 while constraining movement of ceramic 10 perpendicular to its longitudinal axis. May be.

As an alternative, as shown in FIG. 41, the piezoelectric ceramic 10 can be mounted on a fixed base by means of a resilient support element 392. The supporting elasticity is the supporting element 392
Is determined by the rigidity of the material constituting Support element 3
92 is attached to a fixed base (not shown) and extends along the longitudinal axis of the ceramic 10 to about 1/6 of the length of the ceramic.
It is preferable to engage the ceramic 10 at the point of 5/6.

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 the preferred embodiment of the present invention, a number of piezoelectric ceramics are used to increase the read and write capacity of a disk drive. An example of the arrangement shown in FIG. 42 representing two parallel piezoelectric ceramics 10, 10 'is mounted on a shaft 400. This arrangement can be used to simultaneously or alternately read or write to opposite sides of a single disk in order to simultaneously read or write more than one on a single disk. However, for reading or writing to a single sided disc, only one of the piezoceramics 10 or 10 '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 ceramic 10, 10'.

For each piezoceramic, the holes are preferably located between adjacent electrodes along each short end 28, approximately 1/6 of the length of the ceramic.
Only from the respective short ends 28. The piezoceramics 10, 10 'comprise a rotatable shaft 400.
And can move according to a rotating shaft 400. On the other hand, the piezoelectric ceramics 10, 10 '
It can also be rotatably mounted on a shaft 400 fixedly held between the holding elements 404 and 405 so that each can be moved independently. The holding element 4
04, 405 are preferably mounted on a fixed base (not shown).

The piezoelectric ceramics 10, 10 'are mounted on read / write heads 374, 374' by connecting elements 408, 408 ', respectively. The element 408 is preferably attached to or grips the piezoceramic 10 along the long ends 40, 42. Element 408 has an end 2 that is about one-half the length of the ceramic and about five-sixths shorter.
It is preferred to engage the piezoceramic at a point away from 8. Corresponding elements 408 'have long ends 40', 42 '
Are preferably engaged with the piezoceramic 10 'at points 1/2 and 5/6 above. At the above 1/2 and 5/6 points, the ceramics 10, 10 'in the x direction
There is a point where there is no movement, or a change in dimensions. The rigid element 410 is preferably provided with spacers 26, 26 'of the ceramic 10, 10' using elastic elements 411.
It is preferred that each be biased.

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 piezoceramics 10, 10 ', is operated 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 piezoceramics 10 ', 10 "are utilized to rotate the piezoceramic 10 with respect to a shaft 420 suitably mounted on a fixed base (not shown). The spacer 26 is biased against 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 the arm 370 and the read / write attached thereto. Of the head 374 about the shaft 372.

In a preferred embodiment of the present invention, as described above with reference to FIG.
The 0 ', 10 "are fixed with respect to the shaft 420 and can be mounted on said fixed base by means of a shaft mounted on an element slidably mounted on a fixed base (not shown). Alternatively, the piezoceramics 10 ', 10 "can be attached to the fixed base by a fixing element, as shown in Fig. 40, or by other methods described herein. The shaft 420 extends through a hole located at the center of the piezoelectric ceramic 10 and preferably in the intersection region of the four electrodes of the ceramic. The spacer 26 ′ attached to the piezoelectric ceramic 10 ′ is biased toward the concave side of the rigid arcuate element 426. Element 4 above
The convex surface of 26 is preferably mounted approximately at the center of the long end 40 of the piezoelectric ceramic 10. The piezoelectric ceramic 10 'is excited by the spacer 2 according to the applied voltage.
6 'is moved in the y direction or the -y direction. Spacer 2
The force exerted by 6 'on element 426 causes movement of element 426 in accordance with the movement of spacer 26'.

The force exerted on the piezoelectric ceramic 10 by the element 426 causes the piezoelectric ceramic 10 to rotate in the θ direction or the −θ direction. Arc-shaped element 42 similar to element 426
7 is biased against the long end 42 of the piezoelectric ceramic 10 to couple the movement of the spacer 26 "of the piezoelectric ceramic 10" with the rotation of the piezoelectric ceramic 10 as described above for the element 426. preferable. The movement of the spacer 26 ″ in the y direction or the −y direction causes the piezoelectric ceramic 10 to rotate in the −θ direction or the θ direction, respectively, and the rotation direction is substantially the same as that of the spacer 26 ′. The direction opposite to the guided direction, plus the x direction or-
The movement of the spacer 26, which induces a linear movement of the body in the x-direction, can be achieved by direct excitation of the piezoelectric ceramic 10.

Piezoelectric ceramics 10, 10 'and 10 "
Have spacers 26, 26 'and 26 "attached to each piezoelectric ceramic 10, 10' and 10", respectively.
Are preferably electrically connected to correlate the movements of the two. The overall movement of the spacer 26 and the resulting movement of the read / write head 374 consist of a superposition of the movements produced individually by each of the piezoceramics 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. The excitation of the piezoceramics 10, 10 'and 10 "is read out /
A wide variety of motion profiles for the writing head 374 can be achieved.

[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 ceramic element useful in a motor according to a preferred embodiment of the present invention.

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

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

FIG. 4 shows a first excitation form 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 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 shows a bimorph-like movement of a piezoelectric element useful for 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 ceramic element useful in a motor according to a preferred embodiment of the present invention.

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

FIG. 12 shows x- according to a preferred embodiment of the present invention.
FIG. 4 shows a perspective view of a piezoceramic element adapted for y-motion.

FIG. 13 shows xy according to a preferred embodiment of the present invention.
FIG. 3 shows a perspective view of two piezoceramic elements adapted for movement.

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

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

FIG. 16 shows another electrode shape for a piezoelectric ceramic according to a preferred embodiment of the present invention.

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

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

FIG. 22 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. 23 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. 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, illustrating a preferred xy resonance mode of the piezoelectric ceramic of the micromotor.

FIG. 27 is a schematic diagram of a pulse excitation signal for driving the piezoelectric ceramic of the micromotor of FIG. 25 according to one preferred embodiment of the present invention.

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 rigid arms to provide increased power and smoother movement 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 impart a symmetrical movement parallel to the short edge of the piezoelectric ceramic according to a preferred embodiment of the present invention.

FIG. 37 is a schematic diagram of yet another micromotor adapted to impart a symmetrical movement parallel to the short edge of a piezoelectric ceramic 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 according to a preferred embodiment of the present invention.
FIG. 10 is a schematic diagram showing another form of the read / write arm of the disk drive of FIG.

FIG. 40 according to a preferred embodiment of the present invention.
FIG. 10 is a schematic diagram showing another form of the read / write arm of the disk drive of FIG.

FIG. 41 according to a preferred embodiment of the present invention.
FIG. 10 is a schematic diagram showing another form of the read / write arm of the disk drive of FIG.

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

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

[Explanation of symbols]

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

Claims (11)

[Claims] A piezoelectric plate having first and second long sides and first and second short sides; and an arm pivotable about an axis, the first ends extending in opposite directions from the axis. An arm having a second end, a read / write head provided at the first end, and a rigid body provided at the second end, wherein the piezoelectric plate is It is provided at two ends,
The side of the piezoelectric plate, or an extended portion thereof,
A disk drive resiliently biased by said rigid element. 2. The disk drive according to claim 1, wherein said piezoelectric plate is stationary. 3. The disk drive according to claim 1, wherein the piezoelectric plate is movable with respect to the axis. 4. An arm pivotable about an axis, the arm having first and second ends, a read / write head attached to the first end, and an arm attached to the arm. A fixed piezoelectric plate, wherein the shaft extends through the piezoelectric plate. 5. The disk drive according to claim 4, further comprising a hard element biased against said piezoelectric plate. 6. An arm rotatable around an axis, a head for reading or writing provided at one end of the arm, and a head rotatable around the axis together with the arm.
A disk drive comprising: a piezoelectric plate having two long sides and two short sides; and a fixed member for urging a side of the piezoelectric plate or a spacer attached to the side. 7. The disk drive according to claim 6, wherein said shaft passes through a piezoelectric plate. 8. The disk drive according to claim 4, wherein the piezoelectric plate is rectangular. 9. The disk drive according to claim 1, wherein the piezoelectric plate is provided so as to be rotatable around a second axis. 10. The disk drive according to claim 9, further comprising at least another micromotor for rotating the piezoelectric plate about the second axis. 11. The disk drive according to claim 6, wherein said spacer is made of ceramic.