JPH07159150A - Driving method for spanworm type driving mechanism - Google Patents

Abstract

PURPOSE:To suppress the abrasion and vibration between a movable member and an extensible/contractible element and improve the positioning precision of the movable member, by smoothly holding and releasing the movable member by smoothly forming the wave form of the driving voltage applied to the extensible/contractible element for each clamp. CONSTITUTION:Counters 20, 30, and 40 and look-up tables (LUT) 21, 31, and 41 are connected to the elements for extension and contraction 103, 102, and 104, respectively. For example, in the extensible/contractible element 103 for clamp, the clock supplied from a clock generator 11 is frequency-divided by the counter 20, and the serrate digital signal which increases monotonously with a prescribed bit width is inputted to the LUT 21. In the LUT 21, the smooth voltage wave form applied to the extensible/ contractible element 11 is written in, and converted into the digital signal which smoothly varies according to the input value. The signal is D/A converted 22, and amplified by a driving amplifier 23, and the extensible/contractible element 103 is driven. It is similar in the case of the extensible/contractible elements 102 and 104. Accordingly, the abrasion and vibration at the contact part between the extensible/contractible elements 103, 102 and 104 and a movable member are suppressed, and the positioning precision can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving method of a scale insect type drive mechanism used as a coarse movement mechanism of a probe of a scanning probe microscope.

[0002]

2. Description of the Related Art In recent years, following the development of a scanning tunneling microscope capable of directly observing the electronic structure of surface atoms of a conductor sample, an atomic force microscope etc. capable of observing an insulating sample in an atomic order have been developed. It was These new microscopes
It is generally called a scanning probe microscope (hereinafter referred to as "SPM"), and various applications are considered. In particular, applications as a recording device for writing information in a recording medium with high resolution and a reproducing device for reading information written in the recording medium with high resolution are being advanced.

In the device to which the SPM technology is applied, since the probe and the sample are brought close to each other by about 1 nm,
Advanced precision control technology is required. Therefore, a scale-worm type drive mechanism is used as a coarse movement mechanism for bringing the probe and the sample close to each other or moving the probe to an observation place at an arbitrary position on the sample surface.

As shown in FIG. 5, in the stripworm type drive mechanism, two movable telescopic elements 102 each having a central portion fixed to a fixed member 101 sandwich a movable member 105 therebetween and move in the moving direction of the movable member 105. The first elastic member 103 for clamping and the second elastic element 103 for clamping for clamping the movable member 105 are arranged at both ends thereof so as to expand and contract (left and right direction in the drawing).
And the clamp expansion / contraction element 104 are arranged and fixed so as to expand / contract in the vertical direction in the drawing. A laminated piezoelectric element is used as each moving elastic element 102 and each clamping elastic element 103, 104.

Next, the operation of the length-adjusting insect drive mechanism will be described with reference to FIGS. 6 and 7.

First, an expanding voltage is applied to the first clamp elastic element 103, and the first clamp elastic element 103 is applied.
The movable member 105 is composed of the second expansion / contraction element 104 for clamping.
Is held (T1).

Next, the second clamp expansion / contraction element 104.
A contracting voltage is applied to the second clamp expansion / contraction element 104.
The holding of the movable member 105 due to is released (T2), and a voltage that extends to the moving expansion / contraction element 102 is applied (T3). Since the central portion of the moving elastic element 102 is fixed to the fixing member 101, applying a voltage that extends to the moving elastic element 102 causes the first clamping elastic element 103 to move to the right in the figure, and The second telescopic element 104 for clamping moves to the left in the drawing. At this time, since the movable member 105 is held by the first clamp elastic element 103, the movable member 105 moves rightward in the drawing as the first clamp elastic element 103 moves. Movable member 1
The movement amount of 05 is about half of the extension amount of the expansion element 102 for movement.

Then, the second expansion / contraction element 104 for clamping.
Then, the movable member 105 is held again by the first clamp elastic element 103 and the second clamp elastic element 104 (T4). After that, a contracting voltage is applied to the first clamping elastic element 103 to release the holding of the movable member 105 by the first clamping elastic element 103 (T5), and a contracting voltage is applied to the moving elastic element 102 (( T6). As a result, the movable member 105 further moves to the right in the figure by about half the amount of contraction of the moving expansion / contraction element 102.

[0009]

However, in the driving method of the above-described conventional scale-worm-type driving mechanism, the voltage applied to each of the clamp expansion / contraction elements is stepwise as shown in FIG. Therefore, since the holding and releasing of the movable member is rapidly performed by the expansion and contraction element for each clamp,
When the movable member is held or released, vibration may occur at the contact portion between the movable member and the clamp expansion / contraction element, or wear of the contact portion may be accelerated, resulting in poor positioning accuracy of the movable member. It was

Therefore, according to the present invention, by smoothing the movement of holding or releasing the movable member, vibration and wear at the contact portion between the movable member and the clamp expansion / contraction element are suppressed, and the positioning accuracy of the movable member is improved. It is an object of the present invention to provide a driving method of a scale insect type drive mechanism.

[0011]

In order to achieve the above object, a driving method of a scale-worm type drive mechanism according to the present invention is for a plurality of clamps for holding a movable member at two places, each of which expands and contracts by applying a drive voltage. An expanding / contracting element and a moving expanding / contracting element for expanding and contracting in the moving direction of the movable member by applying a drive voltage for moving the movable member are used to hold one position of the movable member to expand / contract the moving member. After stretching the element, while holding the other part of the movable member and releasing the holding of one part, the movable expansion element is contracted, in the method of driving the scale insect type drive mechanism, to each of the clamp expansion elements. The feature is that the waveform of the applied drive voltage is smoothed.

Further, the rising and falling of the waveform of the drive voltage applied to each of the clamp expansion / contraction elements is smoothed.

Further, the waveform of the drive voltage applied to each of the clamp expansion / contraction elements may be stored in a predetermined table, or may be selected in relation to the drive frequency of the scale insect drive mechanism. Good.

[0014]

According to the driving method of the stripworm type drive mechanism of the present invention configured as described above, the waveform of the drive voltage applied to each clamping elastic element is smoothed to hold the movable member by each clamping elastic element. And the release operation becomes smooth. As a result, vibration and wear at the contact portion between the movable member and each of the clamp expansion / contraction elements are suppressed, and the positioning accuracy of the movable member is improved.

[0015]

Embodiments of the present invention will now be described with reference to the drawings.

(First Embodiment) FIG. 1 is a block diagram of a drive circuit used to carry out a first embodiment of a drive method for a scale-worm type drive mechanism according to the present invention. Since the stripworm drive mechanism is the same as the conventional one shown in FIG. 5, its description is omitted, and the drive circuit shown in FIG. 1 will be described below.

The controller 10 controls the movements of the first clamp elastic element 103, the second clamp elastic element 104, and the movable elastic element 102. The clock generator 11 and the respective elastic elements 103 and 104 are controlled by the controller 10. , 102 and respective look-up tables (LUTs) 21, 31, 41 provided for each of the counters 102, 102, and 102 are connected to perform control such as driving frequency setting and resetting.

First, a circuit (upper circuit in the figure) related to driving the first clamp expansion / contraction element 103 will be described. The counter 20 divides the clock from the clock generator 11, and the value of the counter 20 monotonically increases with a predetermined bit width, returns to zero after the input of the reset signal, and the value monotonically increases again. A (sawtooth) digital signal is output. The look-up table 21 is for converting a digital signal whose value changes in a sawtooth wave shape into a preset digital signal, and is written with a voltage waveform to be applied to the first clamping expansion / contraction element 103. When a digital signal is input from the counter 20 to the look-up table 21, a digital value corresponding to the input value is output from the look-up table 21 to the D / A converter 22 with a predetermined bit width. Here, by appropriately setting the relationship between the input and the output, it becomes possible to output a signal that changes smoothly when a signal whose value changes in a sawtooth waveform is input. Lookup table 2 like this
1 includes, for example, a ROM (read-only memory), in which data is appropriately written corresponding to each address of the ROM, and an input signal is given as an address. The output of the look-up table 21 is converted into an analog value by the D / A converter 22 and further amplified by the drive amplifier 23 to drive the first clamp elastic element 103.

The circuit related to driving the second clamping elastic element 104 (lower circuit in the drawing) and the circuit related to driving the moving elastic element 102 (lower circuit in the drawing) are similarly configured, Second clamp telescopic element 104
The movable expansion / contraction element 102 is driven according to the lower lookup table 41 and the middle lookup table 31, respectively.

When each of the expansion / contraction elements 102, 103, 104 of the scale insect type drive mechanism is driven at the same timing as in the conventional case using such a drive circuit, the movable member 105 moves to the right in the figure as shown in FIG. As the voltage waveform moves, the rising and falling of the voltage waveform become smooth as shown in FIG. As a result, the operation of holding and releasing the movable member 105 by the first clamp telescopic element 103 and the holding and releasing of the movable member 105 by the second clamp telescopic element 104 become smooth. Vibration and wear at the contact portions with the clamp elastic elements 103 and 104 are suppressed, and the positioning accuracy of the movable member 105 is improved.

FIG. 2 shows an example in which the movable member 105 is moved to the right in FIG. 6, but in the reverse procedure (procedure from T6 to T1), the expansion / contraction elements 102, 1 are arranged.
By driving 03 and 104, the movable member 105 can be moved in the opposite direction, and by adjusting the voltage applied to the expansion element 102 for movement, one cycle from T1 to T6 or from T6 to T1. The amount of movement of the movable member 105 can be changed with.

Then, the STM-type drive mechanism is used as an STM.
When the probe was used as a coarse movement mechanism for bringing the sample and the sample relatively close to each other and was driven by the driving method of this example, accurate and quiet driving could be performed. In addition, the movable member 1 in one cycle
The variation of the moving distance of 05 was smaller than that of the conventional driving method, and the moving amount of one cycle was almost constant even when used for a long time.

Further, the drive frequency of the scale insect type drive mechanism can be changed by changing the frequency of the clock generated by the clock generator 11, and the lookup tables 21, 31, 41 corresponding to the clock frequency must be prepared. Then, it becomes possible to drive at the driving frequency.
These controls can be performed by the controller 10 as needed.

(Second Embodiment) FIG. 3 is a block diagram of a drive circuit used to carry out a second embodiment of the driving method of the tapeworm drive mechanism of the present invention. Since the stripworm drive mechanism is the same as the conventional one shown in FIG. 5, its description is omitted, and the drive circuit shown in FIG. 3 will be described below.

The sequencer 51 includes a first clamp expansion / contraction element 103, based on the clock from the clock generator 50.
Each elastic element 1 is determined by determining the timing of the voltage applied to the second clamp elastic element 104 and the moving elastic element 102.
The buffer 6 provided for each of the expansion / contraction elements 103, 102, 104, which controls the movement of the expansion elements 02, 103, 104.
0, 70, 80. Each buffer 60, 7
The outputs from 0 and 80 are low-pass filters (L
PF) 61, 71, 81 and amplification amplifiers 62, 72,
It is input to each expansion element 103, 102, 104 via 82. From the sequencer 51 to the buffers 60, 70,
The signal input to 80 is a step-like logic signal, but when it passes through the low-pass filters 61, 71, 81, it becomes a smooth waveform as shown in FIG. 4, and is amplified by the amplifiers 62, 72, 82, respectively. The respective expansion / contraction elements 103, 102, 104 are driven. The drive timing of each expansion / contraction element 103, 102, 104 is the first
The description is omitted because it is the same as the embodiment.

In this way, each drive amplifier 62, 72, 8
The low-pass filters 61, 71, 81 are provided in the preceding stage of 2 respectively.
With a simple configuration of inserting each expansion element 102, 10
Although the initial rising edge and the initial falling edge of the driving waveforms 3 and 104 are steep, compared with the conventional driving method,
The operation of holding and releasing the movable member 105 by the clamp elastic element 103 and the second clamp elastic element 104 is smooth.

Also in this embodiment, by changing the frequency of the clock generated by the clock generator 50, it is possible to change the driving frequency of the worm-type drive mechanism.
Low pass filters 61, 7 corresponding to the clock frequency
By setting the cut-off frequencies of 1 and 81, it becomes possible to drive in accordance with the drive frequency.

In each of the above-described embodiments, an example in which the position of each moving expansion / contraction element 102 is fixed and the movable member 105 is moved is shown as the worm-type insect driving mechanism, but the movable member 105 is fixed and each moving member is moved. The expansion / contraction element 102 may be moved. Alternatively, a cylindrical member may be used as the movable member, and the movable member may be inserted into the hollow portion of the cylindrical expansion / contraction element for movement. Further, the drive waveform is not limited to the shapes shown in FIGS. 2 and 4, and may be a half cycle such as a sine wave or a part thereof. The drive waveform of each moving expansion / contraction element 102 does not necessarily have to have a smooth rise and fall, and may be a waveform similar to the conventional drive waveform.

[0029]

As described above, according to the driving method of the scale insect type drive mechanism of the present invention, the waveform of the drive voltage applied to each of the clamp elastic elements is made smooth so that the movable member of each clamp elastic element can be moved. It is possible to suppress vibration and wear at the contact portion between the movable member and each of the clamp expansion / contraction elements during the holding and releasing operations, and improve the positioning accuracy of the movable member.

[Brief description of drawings]

FIG. 1 is a first driving method for a scale-worm type drive mechanism according to the present invention.
FIG. 3 is a block diagram of a drive circuit used to implement an embodiment.

FIG. 2 is a timing chart of drive waveforms of respective expansion and contraction elements provided by the drive circuit shown in FIG.

FIG. 3 is a second driving method of the scale insect driving mechanism according to the present invention.
FIG. 3 is a block diagram of a drive circuit used to implement an embodiment.

FIG. 4 is a timing chart of drive waveforms of respective expansion and contraction elements provided by the drive circuit shown in FIG.

FIG. 5 is a schematic configuration diagram of a stripworm driving mechanism.

FIG. 6 is a diagram continuously showing the operation of the scale-worm-type drive mechanism shown in FIG.

FIG. 7 is a timing chart of conventional drive waveforms of the stripworm type drive mechanism shown in FIG.

[Explanation of symbols]

 10 Controller 11, 50 Clock Generator 20, 30, 40 Counter 21, 31, 41 Look-up Table (LUT) 22, 32, 42, 62, 72, 82 D / A Converter 23, 33, 43 Amplification Amplifier 51 Sequencer 60, 70, 80 Buffer 61, 71, 81 Low-pass filter (LPF) 101 Fixing member 102 Moving elastic element 103 First clamping elastic element 104 Second clamping elastic element 105 Movable member

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiro Tagawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (4)

[Claims] 1. A plurality of clamp expansion / contraction elements, each of which expands / contracts when a drive voltage is applied, for holding the movable member at two positions, and a movable voltage of the movable member that is applied by applying a drive voltage for moving the movable member. Using a moving elastic element that expands and contracts in the moving direction, holds one position of the movable member, and after stretching the moving elastic element, holds the other position of the movable member and holds one position. In the driving method of the scale insect type drive mechanism, wherein the movable telescopic element is contracted, the waveform of the drive voltage applied to each of the clamp elastic elements is smoothed, and the scale insect driving mechanism is driven. Method. 2. The driving method for a scale insect driving mechanism according to claim 1, wherein the rising and falling of the waveform of the driving voltage applied to each of the clamp elastic elements is smoothed. 3. The method for driving a scale-worm type drive mechanism according to claim 1, wherein the waveform of the drive voltage applied to each of the clamp expansion / contraction elements is stored in a predetermined table. 4. The drive of the scale-worm drive mechanism according to claim 1, 2 or 3, wherein the waveform of the drive voltage applied to each of the clamp expansion / contraction elements is selected in relation to the drive frequency of the scale-worm drive mechanism. Method.