JPH05126518A - Fine-move device and information recording and/or reproduction device using it - Google Patents

Abstract

PURPOSE:To eliminate an unneeded stress which is applied to a piezoelectric element by applying a drive voltage which changes in opposite phase accurately to a pair of piezoelectric elements which are installed on both sides of a part to be driven. CONSTITUTION:Piezoelectric elements 13a and 13b on both sides of a movable part 12 are connected in series and a constant voltage of X(V) is applied to both edges and then the application voltage is divided by resistors 14a and 14b for obtaining an intermediate potential. A drive voltage DELTAX which is amplified by an amplifier 15 is added to the intermediate potential by an adder 16 and is applied to a series-connection point of the piezoelectric elements 13a and 13b. The amount of increase (decrease) of voltage which is applied to one piezoelectric element accurately matches the amount of decrease (increase) of voltage which is applied to the other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device and a recording and / or reproducing device using the driving device, which can be suitably applied to, for example, a scanning tunnel microscope or a device requiring precise position control.

[0002]

2. Description of the Related Art A fine movement driving means using a conventionally known piezoelectric element is disclosed in, for example, US Pat. No. 3,786,332.
As shown in No. 1 and the like, the piezoelectric elements provided before and after in the driving direction of the driven part are configured to drive the driven part so as to reduce the other when one is expanded. There is.

As an actual driving method, for example, the one shown in FIG. 6 is known. In this case, a pair of polarized piezoelectric elements 1a and 1b having the same characteristics are connected in series in the forward direction to form a fine movement drive mechanism in which the movable portion 2 is sandwiched, and both piezoelectric elements 1a and 1b are provided. A forward bias voltage VB having the same magnitude is applied to extend the same amount, and one drive signal is amplified by two amplifiers 3a and 3b whose output polarities are opposite to each other. By superimposing the voltage, the two piezoelectric elements 1a,
The movable portions 2 are moved by increasing / decreasing the extension amounts of 1b so as to be opposite to each other.

[0004]

However, in the above case, unless the characteristics of the two amplifiers 3a and 3b are exactly symmetrical with opposite polarities, the drive voltage applied to both piezoelectric elements 1a and 1b is delicate. A displacement occurs, and for example, when one piezoelectric element 1a expands, the other piezoelectric element 1b does not contract by the same amount. Therefore, the piezoelectric element 1
Unnecessary stress is applied to the piezoelectric elements 1a and 1b.
This results in accelerating the deterioration of b.

In view of the above-mentioned drawbacks of the conventional example, an object of the present invention is to perform a precise fine movement drive and to improve the durability and safety of the device, and an information recording and / or information recording device using the same.
Alternatively, it is to provide a reproducing apparatus.

[0006]

A drive device according to a specific invention for achieving the above object is a pair of piezoelectric devices, which are arranged on both sides of an object and whose electrode arrangement directions are substantially the same. A predetermined voltage is applied between the element and the respective outer electrodes of the pair of piezoelectric elements, an equipotential is given to the inner electrodes of the pair of piezoelectric elements, and the value of the potential given to the inner electrodes is By changing,
A control circuit for driving an object to the pair of piezoelectric elements is provided.

The drive device of the second invention relating to the above-mentioned specific invention is arranged on both sides of the object in the first direction, and the electrode arrangement direction of each of the first pair is substantially the same as the first direction. A predetermined voltage is applied between the piezoelectric element and the outer electrodes of the first pair of piezoelectric elements to apply an equal potential to the inner electrodes of the first pair of piezoelectric elements. A first control circuit for causing the first pair of piezoelectric elements to drive the object in the first direction by changing a value of a potential applied to the electrodes of the first pair of piezoelectric elements, and outer portions of the first pair of piezoelectric elements. And a second pair of piezoelectric elements which are respectively disposed on both sides of a support body that supports the second direction different from the first direction of the support body, and the respective electrode arrangement directions substantially coincide with the second direction. An element and the second pair of piezoelectric elements. By applying a predetermined voltage between the respective outer electrodes, applying an equipotential to the inner electrodes of each of the second pair of piezoelectric elements, and changing the value of the potential applied to the inner electrodes, A second control circuit for driving the support in the second direction is provided on the second pair of piezoelectric elements.

Further, an information recording and / or reproducing apparatus of a third invention related to the above specified invention is an apparatus for recording and / or reproducing information on an information recording medium, and a supporting portion for supporting the information recording medium. A probe for recording and / or reproducing information on / from the information recording medium supported by the support, a stage on which one of the support and the probe is installed, and both sides of the stage. Place and
Each electrode has a pair of piezoelectric elements that are substantially aligned in one direction, and a predetermined electrode is applied between the outer electrodes of the pair of piezoelectric elements. Control circuit for causing the pair of piezoelectric elements to drive the stage by changing the value of the potential applied to the inner electrode, and to relatively move the probe and the information recording medium. And an information recording and / or reproducing apparatus.

[0009]

In the driving device having the above-described structure and the information recording and / or reproducing device using the driving device, the sum of the voltages applied to the respective piezoelectric elements is always equal to a constant voltage, so that only one driving voltage is changed. The voltage applied to the two piezoelectric elements can be increased or decreased, and the increase amount of the voltage applied to one piezoelectric element exactly matches the decrease amount of the voltage applied to the other piezoelectric element.

[0010]

Embodiments will be described in detail below with reference to the embodiments shown in FIGS. FIG. 1 is a principle explanatory view of a first embodiment of the present invention, in which piezoelectric elements 13a and 13b are provided on both sides of a movable portion 12 slidably attached to a guide mechanism 11.
Are attached, and for example, both are polarized in the same direction so that the positive electrode appears at the left end.

The negative electrode of the right piezoelectric element 13b thus arranged is grounded to the reference potential, and a constant voltage of X (V) is applied to the positive electrode of the other piezoelectric element 13a. By doing so, the piezoelectric element 1
The direction of the voltage applied to 3a and 13b always matches the polarization direction. Further, this applied voltage is divided by two resistors 14a and 14b having the same resistance value R to obtain an intermediate potential of X / 2 (V), and the amplifier 15 uses, for example, ΔX (V ) Is obtained, and X / 2 + ΔX (V) obtained by adding both by the adder 16 is applied to the remaining electrodes of the piezoelectric elements 13a and 13b.

In this way, if the drive voltage ΔX fluctuates based on the change of the drive signal, the two piezoelectric elements 13a,
13b indicates that the voltage applied between both electrodes is X
Left and right piezoelectric elements 13a, 13b centered on / 2 (V)
Applied to. The electric potential increases on the one hand and decreases on the other hand, so that one of the piezoelectric elements 13a and 13b expands and the other contracts.

For example, in the voltage change diagram of FIG. 2, (a)
, (C) and (e), in the equilibrium state in which the drive voltage ΔX is zero, the output of the adder 16 becomes X / 2 (V), and both piezoelectric elements 13a and 13b have X / 2 (V). Since the same voltage is applied, the movable parts 12 are located at the center because they are expanded by the same amount. On the other hand, when a positive drive voltage ΔX is given as shown in (b), the output of the adder 16 becomes X /
Since it is 2 + ΔX (V), X / 2 + ΔX (V) is applied to the ground side piezoelectric element 13b, while the voltage applied to the other piezoelectric element 13a is X / 2−ΔX (V). As a result, the piezoelectric elements 13a and 13b contract and expand symmetrically with respect to the expansion amount in the case of X / 2 by the amount corresponding to ΔX (V).
If the outer ends of a and 13b are regulated, the movable part 12
Is driven to the left along the guide mechanism 11. In addition,
If the drive voltage is set to -ΔX as shown in (d), the opposite expansion and contraction occurs and the movable portion 12 is driven rightward.

As described above, in the embodiment, since only one amplifier 15 is used to change the driving voltage applied to the two left and right piezoelectric elements 13a and 13b, both piezoelectric elements can be easily and accurately. Expansion and contraction of 13a and 13b can be reversed, and accurate driving of the movable portion 12 can be realized.
It is possible to drive the piezoelectric elements 13a and 13b with the above wirings as they are by reversing the lateral relationship with respect to the movable portion 12. In this case, the driving direction of the movable portion 12 is opposite to that in the above case.

FIG. 3 is a block diagram of the second embodiment, and FIG.
The same reference numerals as in FIG. In FIG. 3, elastic hinge springs 11a, 11b, 11c, 11d
The movable part 12 that is movable in the left-right direction in the drawing by the guide mechanism that is formed in the center of the first frame 17 is arranged in the left-right gap between the movable part 12 and the frame 17. For example, a piezoelectric element 13a having a sensitivity of 0.1 (μm / V),
13b is extended by ± 5 (μm) when a voltage of ± 50 (V) is applied to each of them.

In the second embodiment, the resistor 14
The resistance values R of a and 14b are equal, for example, 10 (kΩ), the gain of the amplifier 15 is 10 times, and the constant voltage X is constant.
100 (V) is applied by the high-voltage amplifier 18. In addition, the second frame body 19 is provided outside the first frame body 17.
Are arranged, and the first frame body 17 has an elastic hinge spring 11e,
By the guide mechanism consisting of 11f, 11g and 11h,
Piezoelectric elements 13c and 13d that are movably supported in the vertical direction in the drawing from the second frame 19 and are provided in the upper and lower gaps can relatively drive the frame body 17 and the drive unit 12 in the vertical direction in the drawing. Has been done. The piezoelectric elements 13c and 13d
The power supply circuit for driving the
The circuit has exactly the same configuration as the circuit for driving b, and is not shown in order to avoid complication.

With the above-mentioned structure, when the drive signal is zero for the piezoelectric elements 13a and 13b, that is, the drive voltage from the amplifier 15 is zero, the resistor 1 is connected to the piezoelectric elements 13a and 13b.
50 (V) each divided by 4a and 14b is applied, the piezoelectric elements 13a and 13b are extended by the same amount of 5 (μm), and the left and right gaps between the movable portion 12 and the frame body 17 are the same. Becomes the amount. In this state, if a triangular wave having a maximum amplitude of ± 1 (V) is input to the amplifier 15 as a drive signal, the amplitude will be ± 10.
A drive voltage of (V) is obtained, and for example, ΔX = + 10 (V)
In this case, the output of the adder 16 becomes 60 (V), 40 (V) for the piezoelectric element 13a and 60 (V) for the piezoelectric element 13b.
(V) will be applied. As a result, the piezoelectric element 1
3 a is 4 (μm), the piezoelectric element 13 b is extended by 6 (μm) from the initial length, and the movable portion 12 is displaced to the left by 1 (μm) from the center with respect to the frame body 17. Conversely, ΔX = -1
At 0 (V), the output of the adder 16 becomes 40 (V),
As a result, the movable portion 12 is displaced to the right by 1 (μm) from the center. It should be noted that the movable portions 12 can be finely moved in the vertical direction by the same drive control for the piezoelectric elements 13c and 13d.

As described above, in the present embodiment, the drive voltage ΔX is changed within the range of -50 (V) to +50 (V) at the maximum, so that the position of the movable portion 12 is moved to the left, right, up and down from the center by 5 (5). It is possible to freely control in the range of (μm). For this purpose, the drive signal input to the amplifier 15 may be changed within the range of −5 (V) to +5 (V), and a triangular wave or sine wave signal may be input to vibrate the movable portion 12 without distortion. It's also easy.

In the embodiment described above, the resistors 14a, 14b.
However, it is also possible to shift the reference value from the center when the drive voltage ΔX is zero by unequally dividing the resistance value such as 7 to 3.

In any of the above cases, if the drive voltage ΔX exceeds a certain voltage X or falls below the ground potential,
In order to prevent deterioration of the piezoelectric element 13, it is desirable to limit the piezoelectric elements 13a and 13b so that an electric field opposite to the polarization direction is not applied.

FIG. 4 shows a third embodiment of the high-voltage amplifier 18 of the second embodiment, in which the amplification is variable.
It is different from the second embodiment only in that an amplification factor controller 20 which replaces the amplification factor a and controls the amplification factor of the amplifier 18a is newly provided.

In these examples, the piezoelectric element 13
Although a and 13b are inserted on the left and right sides of the movable portion 12 and the frame body 17, it is difficult to accurately process the piezoelectric element insertion portion,
For example, if a processing error occurs when a certain device is manufactured, even if the piezoelectric elements 13a and 13b are similarly fixed and a voltage is applied, there is a difference in the preload applied to the piezoelectric element with respect to a normal fine movement driving device. Will occur. In this case, if the preload applied to the piezoelectric element of the device in which this error has occurred is too large, the expected amount of displacement cannot be obtained.

Specifically, there is a possibility that the preload may vary by about ± 10 (kgf) and the displacement amount of the piezoelectric elements 13a and 13b may vary by about ± 0.1 (μm) depending on the processing accuracy. In this case, the device manufacturer can adjust the gain by operating the amplification factor controller 20 and changing the voltage applied to the positive electrode side voltage of the piezoelectric element 13a by the high voltage amplifier 18a. In this case, by varying about ± 5 (V), the preload applied to the piezoelectric elements 13a and 13b can be adjusted, and the displacement amounts can be made uniform. For example, when the preload is too large as described above, the piezoelectric element 1
The controller 20 lowers the amplification factor so as to lower the voltage value applied to the positive electrode of 3a. In this way, the piezoelectric element 13
Since the constant voltage applied to the outside of a and 13b can be changed, the displacement amount of the movable portion can be made uniform, and the individual difference of the fine movement drive device can be eliminated.

FIG. 5 is a block circuit diagram of an information recording / reproducing apparatus according to the fourth embodiment, which is an xy direction coarse movement mechanism 21.
The recording medium 22 is placed on the above, and the coarse movement within the xy plane is possible. Above this, the z direction fine movement coarse movement mechanism 23 is disposed and attached to the driven portion on the lower surface thereof. The xy-direction fine movement mechanism 24 drivably supports a probe electrode 25 made of tungsten formed by electrolytic polishing, and the tip of the probe electrode 25 is close to the surface of the recording medium 22.
The recording medium 22 is formed by polishing glass and then forming a base electrode 27 by vacuum-depositing gold (Au) using chromium as an undercoat layer on a substrate 26, and forming a graphite (HOP) layer on the base electrode 27.
The recording layer 28 made of G) is adhered with a conductive adhesive, and the recording / reproducing area on the surface of the recording layer 28 is smoothed by cleavage by an atomic order. On the other hand, the interface 29 for connecting to the host device of the information recording / reproducing apparatus is connected to the drive mechanism and the recording medium 22 and the probe electrode 25 through the following electric circuits.

That is, a control circuit 30 for performing centralized control of mutual operations between blocks in the information recording / reproducing apparatus, a write / read circuit 31 for writing / reading write / read data according to an instruction from the control circuit 30, Embedded read circuit 3
1 based on the signal from the probe electrode 25 and the base electrode 2
7 is applied with a pulse voltage to write data, and a read voltage is applied at the time of reading, a current flowing between the probe electrode 25 and the recording medium 22 is amplified, and this is read at the time of reading information. Positioning circuit that determines the position in the x-direction or the y-direction based on signals from the current-voltage amplification circuit 33 and a position detection circuit to be described later according to instructions from the current-voltage amplification circuit 33, the control circuit 30, and the like that are sent as signals to the write / read circuit 31. 34, a servo circuit 35 that servo-controls the position in the x direction and the y direction based on the servo signal from the positioning circuit 34, a z direction drive circuit 36 that drives the z direction fine movement coarse mechanism 23 in accordance with the signal of the servo circuit 35, Servo circuit 35
Xy direction fine movement drive circuit 37f for respectively driving the xy direction fine movement mechanism 24 and the xy direction coarse movement mechanism 21 in accordance with the signal of
A position detection circuit 38 for detecting the relative position between the probe electrode 25 and the recording medium 22 is provided in the xy direction coarse movement drive circuit 37r.

In this embodiment, the xy direction fine movement mechanism 2 is used.
4 and the xy direction fine movement drive circuit 37f are configured as shown in FIG. 3 or FIG. 4, and the command signal from the servo circuit 35 is input to the amplifier 15 of each of the directional drive circuits, and the command signal is input. Drive control is executed.

Next, the operation of the information recording / reproducing apparatus will be described. In order to prevent the probe electrode 25 from coming into contact with the recording medium 22, the initial position is slightly above, and when used, the probe electrode 25 is brought close to the recording medium 22 by the z-direction fine movement coarse movement mechanism 23. At this time, a read voltage of 200 (mV) is applied by the voltage application circuit 32 to the probe electrode 25 and the base electrode 27 of the recording medium 22.
Is applied between the two, and the current detected by the current-voltage amplifier circuit 33 is brought close to 100 (pA) to hold the z-direction fine movement coarse movement mechanism 23, and thereafter the xy direction fine movement mechanism 24 is used. The recording medium 22 is scanned to record and reproduce. The recording is performed by scanning the recording area of the recording medium 22 column by column with the probe electrode 25 and applying a pulsed voltage from the voltage application circuit 32 at the writing position instructed by the control circuit 30. This pulse-like voltage has a pulse height of 4 (V) and a pulse width of 1 (μs), and is a threshold value for changing the voltage-applied portion of the graphite film into a concave shape.

For reproduction, while applying a read voltage of 200 (mV) between the probe electrode 25 and the base electrode 27 from the voltage application circuit 32, the recording area is scanned by the probe electrode 25 using the xy direction fine movement mechanism 24, Reading is performed from the change in current in the current-voltage amplifier circuit 33.

Although this apparatus was a recording / reproducing apparatus, it goes without saying that it may be a recording-only or reproducing-only apparatus. The writing and reading conditions are not limited to those in the above embodiment, and the xy-direction fine movement drive circuit 37f and the xy-direction fine movement mechanism 24 provided on the probe electrode 25 side may be provided on the recording medium 22 side. ..

[0030]

As described above, in the fine movement drive device and the information recording and / or reproducing device using the same according to the present invention, the increase amount of the voltage applied to one piezoelectric element is accurately compared with the decrease amount of the other piezoelectric element. Since they coincide with each other, the amounts of expansion and contraction of the piezoelectric elements on both sides coincide with each other, unnecessary stress is not applied to the piezoelectric elements, deterioration of the elements can be prevented, and precise fine movement drive can be performed for a long period of time.

[Brief description of drawings]

FIG. 1 is a principle explanatory diagram of a first embodiment.

FIG. 2 is an operation explanatory diagram of a movable portion.

FIG. 3 is a configuration diagram of a fine movement drive mechanism according to the first embodiment.

FIG. 4 is a configuration diagram of a fine movement drive mechanism according to a second embodiment.

FIG. 5 is a block circuit configuration diagram of a recording / reproducing apparatus according to a third embodiment.

FIG. 6 is an explanatory diagram of a conventional fine movement drive device.

[Explanation of symbols]

 11 Guide mechanism 11a-11h Elastic hinge spring 12 Movable part 13a-13d Piezoelectric element 14a, 14b Resistor 15 Amplifier 16 Adder 17, 19 Frame 22 Recording medium 24 XY direction fine movement mechanism 25 Probe electrode

Claims (3)

[Claims] 1. A predetermined voltage is applied between a pair of piezoelectric elements, which are respectively disposed on both sides of an object, and have respective electrode arrangement directions substantially corresponding to each other, and electrodes on the outer sides of the pair of piezoelectric elements. A control circuit for driving an object to the pair of piezoelectric elements by applying an equal potential to the inner electrodes of the pair of piezoelectric elements and changing the value of the potential applied to the inner electrodes. A drive device characterized by the above. 2. A first pair of piezoelectric elements, which are arranged on both sides of the object in the first direction, and the respective electrode arrangement directions substantially coincide with the first direction, and the first pair of piezoelectric elements. By applying a predetermined voltage between the respective outer electrodes of the element, applying an equipotential to the inner electrodes of each of the first pair of piezoelectric elements, and changing the value of the potential applied to the inner electrodes. A first control circuit for causing the first pair of piezoelectric elements to drive the object in the first direction; a support for supporting an outer portion of each of the first pair of piezoelectric elements; The second pair of piezoelectric elements and the second pair of piezoelectric elements, which are arranged on both sides of the second direction different from the first direction, and the respective electrode arrangement directions substantially coincide with the second direction. Apply a predetermined voltage between each outer electrode, Note that by applying an equipotential to the inner electrodes of each of the second pair of piezoelectric elements and changing the value of the potential applied to the inner electrodes, the support member is attached to the second pair of piezoelectric elements. Second driven in two directions
A drive device comprising a control circuit. 3. An apparatus for recording and / or reproducing information on an information recording medium, comprising: a support section for supporting the information recording medium; and information recording on the information recording medium supported by the support section. And / or a probe for performing reproduction, a stage on which one of the support and the probe is installed,
The electrodes are arranged on both sides of the stage, and each electrode has a pair of piezoelectric elements that substantially coincide with each other in one direction,
A predetermined electrode is applied between the outer electrodes of the pair of piezoelectric elements, an equal potential is applied to the inner electrodes of the pair of piezoelectric elements, and the value of the potential applied to the inner electrodes is changed. An information recording and / or reproducing apparatus comprising: a control circuit for driving the stage by the pair of piezoelectric elements to relatively move the probe and the information recording medium.