JPH07191756A - Fine driving device and information recording and/or reproducing device using the same - Google Patents

Abstract

PURPOSE:To realize high-speed and correct fine driving by in creasing intrinsic frequency in a fine driving mechanism using a pair of piezoelectric elements. CONSTITUTION:In the fine driving mechanism in which a pair of the piezoelectric elements 13a, 13b coincident with each other in their electrode arranging directions are fitted before and behind the driving direction of a movable part 12, and the movable part 12 is driven by expanding and contracting a pair of the piezoelectric elements 13a, 13b mutually in the driving direction by impressing voltage to them, tension in the driving direction is increased by shifting mutually the phases of the driving voltage to be impressed respectively to a pair of the piezoelectric elements 13a, 13b.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art A fine movement drive device known in the past is
As shown in FIG. 8, a pair of piezoelectric elements 1a and 1b having the same characteristics, which have been polarized, are arranged in series in the forward direction to form a fine movement drive mechanism in which the movable portion 2 is sandwiched. A forward bias voltage V _B having the same magnitude is applied to both piezoelectric elements 1a and 1b to extend the same amount, and one drive signal is output to each of the two amplifiers 3 whose output polarities are opposite to each other.
a and 3b are amplified, and the obtained drive voltages of opposite phases are superposed on each other so that the two piezoelectric elements 1a and 1b
The amount of expansion of b is increased or decreased so as to be opposite to each other, and the movable portion 2
Are moving.

[0003]

Although the limit of the driving speed of such a fine movement driving device is limited by the natural frequency of the fine movement driving mechanism, a pair of polarized piezoelectric elements having the same characteristics are used as the movable portion. With respect to the fine movement drive mechanism which is arranged in series with respect to each other and drives two piezoelectric elements by extending them in opposite directions,
The force exerted by the two piezoelectric elements in the driving direction of the movable portion (this is referred to as axial force) is one of the largest factors that determine the natural frequency.

The relationship between the axial force and the natural frequency is almost proportional, and the higher the axial force, the higher the natural frequency.

However, in the above-mentioned conventional example, a pair of polarized piezoelectric elements having the same characteristics are arranged in series with respect to the movable portion, and the two piezoelectric elements are simultaneously extended in the opposite directions by the same amount. The axial force applied to the movable part becomes constant,
The natural frequency cannot be raised above a certain level.

In order to increase the axial force, it is sufficient to increase the voltage applied to both ends of the piezoelectric element, but it is not possible to apply more than the withstand voltage of the piezoelectric element, and therefore the natural frequency is also increased. There is a limit.

An object of the present invention is to eliminate the above-mentioned drawbacks of the conventional method by increasing the axial force applied to the movable portion without changing the positional relationship between the movable portion and the piezoelectric element of the conventional fine movement drive mechanism, and to improve the rigidity. It is an object of the present invention to provide a fine movement driving device that can drive fine movement accurately and an information recording and / or reproducing apparatus using the same.

[0008]

In order to achieve the above-mentioned object, the present invention has a pair of piezoelectric elements mounted before and after the driving direction of a movable part so that their respective electrode arrangement directions coincide with each other. A fine movement drive mechanism that causes the pair of piezoelectric elements to operate in opposite directions by a drive voltage that applies expansion and contraction is provided with means for applying the drive voltage while shifting the phase of the drive voltage.

Further, before and after the movable portion in the first driving direction,
A first pair of piezoelectric elements mounted so that their respective electrode arrangement directions are aligned with each other, a support body supporting each outer portion of the first pair of piezoelectric elements, and a first support body of the support body. A second pair of piezoelectric elements mounted on both sides of a second driving direction different from the driving direction such that their respective electrode arrangement directions coincide with each other; and a pair of the first and second piezoelectric elements. A biaxial fine movement drive mechanism that causes the expansion and contraction of the drive voltage to operate in opposite directions to each other is provided with means for applying the drive voltage while shifting the phase thereof.

Further, a supporting portion for supporting the information recording medium, a probe electrode for recording and / or reproducing information on the information recording medium, and a scanning of the probe electrode relative to the information recording medium. In the information recording and / or reproducing apparatus provided with the fine movement driving means, the fine movement driving device is used as the fine movement driving means.

[0011]

The movable portion is acted on by applying a driving voltage having a phase difference to each of a pair of piezoelectric elements mounted before and after the movable portion in the driving direction, within a range that does not reduce the driving amount. The axial force can be easily increased, and the natural frequency of the fine motion drive mechanism can be increased.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The principle of the present invention will be described with reference to FIGS.

FIG. 1 is a principle explanatory view of a fine movement drive device of the present invention. Piezoelectric elements 13a and 13b are attached to both sides of a movable portion 12 which is slidably attached to a guide mechanism 11. Is polarized so that the negative electrode appears in the center.

The fine movement drive mechanism thus arranged grounds the negative electrodes of the piezoelectric elements 13a and 13b to the reference potential, and applies the drive voltage from the amplifier 15 to the other positive electrode. Then, a delay circuit 18 for delaying the phase of the drive voltage is provided between the positive electrode of one of the piezoelectric elements and the amplifier 15. In this description, the delay circuit 1 is provided between the positive electrode of the piezoelectric element 13b and the amplifier 15.
8 is provided.

FIG. 2A shows the change over time of the driving voltage applied to the piezoelectric element 13a and FIG. 2B, respectively, and shows the time variation of the driving voltage applied to the piezoelectric element 13b. Is a positive voltage that varies between

The voltage applied to the piezoelectric element 13b has the same shape as the voltage waveform applied to the piezoelectric element 13a by the delay circuit 18, and the phase is shifted by π.

As the drive voltage waveform, the duty ratio of the AC component of the drive voltage waveform (value of T1 with respect to T2 in FIG. 2) is 1.
Select a waveform that does not.

By selecting the drive voltage waveform as described above and making the phases asynchronous, the displacement amounts of the piezoelectric elements 13a and 13b are not synchronized with each other, and the duty ratio is changed as shown in FIG. 2 (c). The axial force acting on the movable part is higher by a maximum Δf than the axial force (f0) when 1 (T1 = T2). The axial force f1 at that time increases / decreases in (T1 + T2) / 2 cycles. The present invention will be specifically described below with reference to examples.

Embodiment 1 In this embodiment, E = shown as a driving voltage in FIG.
A drive voltage waveform with 100 V, T1 = 120 ms, and T2 = 80 ms was applied to the piezoelectric element 13a. Piezoelectric element 13
A drive voltage waveform having the same shape and a phase difference of π is applied to b by the delay circuit 18.

In the present embodiment, the dut of the AC component of the drive waveform
The axial force f0 when a waveform having a y ratio of 1 is applied to each piezoelectric element by shifting the phase by π is 100 kgf, whereas the axial force f5 is maximal by applying the means of the present invention.
It increased by 0 kgf.

Therefore, the natural frequency of the fine motion drive mechanism increases as the axial force increases.

In this embodiment, a laminated piezoelectric element was used as the piezoelectric element.

FIG. 3 shows the result of measurement of the amount of displacement of the movable portion 12 with respect to the guide mechanism 11 using a non-contact type capacitance sensor according to this embodiment.

By selecting the waveform of the drive voltage as shown in FIG. 2, it is possible to obtain the same displacement amount (5 μm in this example) as before the phase shift.

As described above, in this embodiment, the axial force acting on the movable portion can be changed by shifting the phase of the voltage applied to the piezoelectric element, so that the natural frequency of the fine movement drive mechanism can be increased. It is possible to realize high-speed and accurate driving of the movable portion 12.

The piezoelectric elements 13a,
It is possible to drive even if the left-right relationship of 13b with respect to the movable portion 12 is reversed, and in this case, the driving direction of the movable portion 12 is opposite to the above case.

In this embodiment, the drive voltage waveform is shown in FIG.
Although the waveform shown in (a) is used, this is not a limitation and the duty ratio of the AC component of the drive waveform is 1
Any other waveform may be used, and the waveforms shown in FIGS.

Second Embodiment FIG. 6 is a block diagram of the second embodiment. In FIG. 6, the movable portion 12 that is movable in the left-right direction in the drawing by the guide mechanism including the elastic hinge springs 11a, 11b, 11c, and 11d is arranged in the center of the first frame body 17,
For example, the piezoelectric elements 13a and 13b having a sensitivity of 0.1 (μm / V), which are arranged in the left and right gaps between the movable portion 12 and the frame 17,
For example, when a voltage of 50 (V) is applied to each,
It is designed to extend by 5 (μm).

A second frame body 19 is arranged outside the first frame body 17, and the first frame body 17 is made of the elastic hinge spring 1.
Piezoelectric elements 13c, 13 supported by a guide mechanism composed of 1e, 11f, 11g, 11h so as to be movable in the vertical direction in the drawing from the second frame 19 and provided in the upper and lower gaps.
The frame 17 and the movable portion 12 can be relatively driven in the vertical direction in the drawing by d. The piezoelectric elements 13c, 1
The control circuit for driving 3d includes the illustrated piezoelectric element 13a,
It has exactly the same configuration as the circuit that drives 13b, and is not shown in the figure to avoid complication.

With the above-mentioned structure, the piezoelectric elements 13a and 13b have a waveform as shown in FIG. 2 and an amplitude of 10V.
_{The PP} drive signal is multiplied by 10 through the amplifier 15, and the piezoelectric element 13a remains unchanged, and the piezoelectric element 13b uses the delay circuit 1 as it is.
By 8 the phase is shifted by π and applied.

Each piezoelectric element tries to expand and contract according to the waveform of the driving voltage, but since the piezoelectric elements are located in front of and behind the movable portion 12, the piezoelectric elements cannot expand and contract according to the waveform, and as a result, the axial force is increased. It will be added to the movable part 12. As a result, the natural frequency of the fine movement drive mechanism increases.

The movable portion 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 this embodiment, the natural frequency can be increased by shifting the phase of the voltage applied to the piezoelectric element, and the phase of the drive voltage input to the amplifier 15 is delayed by the delay circuit 18. By delaying the phase by π,
Natural frequency in X direction from 5.6kHz to 6.1kHz
In the Y direction, from 2.6 kHz to 3.0 kHz, 1
It was possible to raise it by about 0%. The natural frequency was calculated by measuring the displacement of the movable part with a capacitance sensor and analyzing it with a spectrum analyzer.

In any of the above cases, the driving voltage exceeds the withstand voltage of each piezoelectric element, or the piezoelectric element 13
In order to prevent the piezoelectric element 13 from being deteriorated, it is desirable to limit the electric fields opposite to the polarization directions to a and 13b.

Embodiment 3 FIG. 7 is a block diagram of an information recording and / or reproducing apparatus according to a third embodiment, in which 21 is a plurality of probe electrodes made by micromechanics technology, and 22 is a plurality. Which is a mechanism for finely moving the probe electrode of Z in the Z direction.
A probe electrode attachment for setting in the direction fine movement mechanism 23, and 24 is a Z direction coarse movement mechanism for coarsely moving a plurality of probe electrodes in the Z direction. 25 is a recording medium,
1 is a substrate obtained by polishing glass, 252 is a substrate 25
A base electrode 253 on which Cr (undercoat layer) and Au are formed by a vacuum vapor deposition method, and 253 is a recording layer of graphite (HOPG). The recording layer 253 is adhered onto the base electrode 252 with a conductive adhesive, and the recording / reproducing area on the surface of the recording layer is smoothed by cleavage by atomic order. Reference numeral 26 is an XY direction fine movement mechanism for finely moving the recording medium 25 in the XY directions.
Reference numeral 7 denotes an XY-direction coarse movement mechanism that coarsely moves the recording medium 25 in the XY directions. Reference numeral 28 denotes an interface for connecting to a recording / reproducing apparatus, which performs input / output of write / read information, output of status, input of control signal, and output of address signal. Reference numeral 280 is a control circuit for performing centralized control of interaction between blocks in the recording / reproducing apparatus, 281 is a write / read circuit for writing / reading write / read information (data) according to an instruction from the control circuit 280, and 282 is write. A plurality of probe electrodes 2 by the command signal from the readout circuit
1 is a voltage application circuit that applies a writing pulse voltage between the recording medium 25 and the recording medium 25 to write data or applies a reading voltage, and 283 is a plurality of probe electrodes 21 and the recording medium during recording / reproduction. A tunnel current detection circuit 284 for detecting a current flowing between the probe electrode 21 and the recording medium 25 is instructed by a control circuit 280 based on signals from the tunnel current detection circuit 283 and the position detection circuit 288. The positioning circuit 285 determines the position of the plurality of probe electrodes 21 and the recording medium 25 based on the servo signal from the positioning circuit 284.
Reference numeral 86 is a Z for driving the Z direction fine movement / coarse movement mechanisms 23, 24 of the plurality of probe electrodes 21 in accordance with the signal from the servo circuit 285.
The direction drive circuit 287 is an XY direction drive circuit which drives the XY direction fine movement / coarse movement mechanisms 26 and 27 of the recording medium 25 in accordance with a signal from the servo circuit 285.

Although only one control circuit 280, write / read circuit 281, voltage application circuit 282, and tunnel current detection circuit 283 are shown in the figure, the number of probe electrodes is actually used.

Next, the operation of the information recording / reproducing apparatus will be described. In order to avoid contact between the plurality of probe electrodes 21 and the recording medium 25, the initial position is slightly above, and when used, the recording medium 25 is moved by the Z-direction fine movement / coarse movement mechanisms 23 and 24.
Approached. At this time, the voltage applying circuit 282 causes 20
A read voltage of 0 (mV) is applied to the probe electrode 21 and the recording medium 2.
5 is applied between the base electrodes 252 of 5 and approached until the current detected by the tunnel current detection circuit 283 reaches 100 (pA), and the Z direction fine movement / coarse movement mechanisms 23 and 24 are held. Recording and reproduction are performed by scanning the recording medium 25 using the XY direction fine movement mechanism 26. Recording is a recording medium 25
This is performed by applying a pulsed voltage from the voltage application circuit 282 at the writing position instructed by the control circuit 280 while scanning the recording area by a plurality of probe electrodes 21 row by row. This pulsed voltage has a pulse height of 4 (V),
The pulse width is 1 (μs), which is a threshold value for changing the surface of the graphite film to which a voltage is applied into a concave shape.

The reproduction is performed by the voltage application circuit 282 between the plurality of probe electrodes 21 and the base electrode 252 at 200 (mV).
While applying the reading voltage of XY direction fine movement mechanism 26
The probe electrode 21 is used to scan the recording area by using, and reading is performed from the change in current in the tunnel current detection circuit 283.

Although this apparatus was a recording / reproducing apparatus, it goes without saying that it may be a recording-only or reproducing-only apparatus. The conditions for writing and reading are not limited to those in the above-described embodiment, and the XY direction fine movement mechanism / coarse movement mechanism 26, 27 provided on the recording medium 25 side is the probe electrode 21.
It may be provided on the side.

When the above-described fine movement drive device is used for the XY direction fine movement mechanism of this information recording and / or reproducing apparatus, high speed writing and reading are possible.

[0041]

As described above, the fine movement drive device and the information recording and / or reproducing device using the same according to the present invention increase the axial force applied to the movable portion by the pair of piezoelectric elements sandwiching the movable portion. Therefore, the natural frequency of the device can be increased, and high-speed and precise fine movement drive can be performed.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2A is a waveform diagram of a voltage applied to a piezoelectric element for explaining the present invention. (B) A waveform diagram of phase-shifted voltages applied to the piezoelectric element for explaining the present invention. (C) A graph showing an increase in axial force for explaining the present invention.

FIG. 3 is a graph showing a displacement amount of a movable portion according to the first embodiment.

FIG. 4 is a waveform diagram of another voltage applied to the piezoelectric element according to the first embodiment.

FIG. 5 is a waveform diagram of another voltage applied to the piezoelectric element according to the first embodiment.

FIG. 6 is a configuration diagram of a fine movement drive device according to a second embodiment.

FIG. 7 is a block circuit configuration diagram of a recording / reproducing apparatus according to a third embodiment.

FIG. 8 is an explanatory diagram of a conventional fine movement drive device.

[Explanation of symbols]

 11 Guide Mechanism 11a-11h Elastic Hinge Spring 12 Moving Part 13a-13d Piezoelectric Element 15 Amplifier 17, 19 Frame 18 Delay Circuit 21 Probe Electrode 25 Recording Medium 26 XY Direction Fine Movement Mechanism

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location H01L 41/09 (72) Inventor Toshimitsu Kawase 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (5)

[Claims] 1. A pair of piezoelectric elements are mounted in front of and behind the driving direction of the movable part so that their respective electrode arrangement directions are aligned with each other, and the pair of piezoelectric elements are made to operate in reverse by driving voltages for applying expansion and contraction of the piezoelectric elements. A fine movement drive device comprising a means for applying a phase of the drive voltage with a shift in the fine movement drive mechanism. 2. A first pair of piezoelectric elements mounted before and after the first driving direction of the movable part so that their respective electrode arrangement directions coincide with each other, and each of the first pair of piezoelectric elements. And a second pair of piezoelectric elements mounted on both sides of a second driving direction different from the first driving direction of the supporting body for supporting the outer part of the piezoelectric body, with their respective electrode arrangement directions aligned with each other. The elements and the first and second pairs of piezoelectric elements are made to operate in reverse with each other by drive voltages that apply expansion and contraction of the piezoelectric elements
A two-axis fine movement drive device, comprising means for applying the drive voltage while shifting the phase of the drive voltage. 3. The duty of an AC component of the drive voltage waveform
3. The fine movement drive device according to claim 1, wherein the ratio is other than 1. 4. The fine movement drive device according to claim 1, wherein a phase difference between drive voltages applied to the pair of piezoelectric elements is π. 5. A support portion for supporting an information recording medium, a probe electrode for recording and / or reproducing information on the information recording medium, and a scanning of the probe electrode relative to the information recording medium. An information recording and / or reproducing apparatus comprising a fine movement driving means, wherein the fine movement driving means according to claim 1 or 2 is used as the fine movement driving means.