JP3095915B2 - Information processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information processing apparatus,
In particular, the present invention relates to an information processing apparatus that records information on a recording medium using a scanning tunneling electron microscope technique and reproduces information from the recording medium.

[0002]

2. Description of the Related Art Memory material technology is at the core of the electronics industry, such as computers and their peripheral devices, video disks, digital audio disks, etc. In recent years, memory materials have been very actively developed. I have. Conventionally, magnetic memories and semiconductor memories made of magnetic materials and semiconductors have been the mainstream, but with the development of laser technology, optical memories using organic thin films such as organic dyes and photopolymers have appeared. I have. Optical memories are inexpensive and high-density recording media.

On the other hand, the electronic structure of surface atoms of a conductor is directly observed.
Scanning Tunneli
ng Microscope, hereinafter abbreviated as STM. ) Is developed
[G. Binnig et al., Phys. Rev. Lett.,Four
9, 57 (1982)], whether single-crystal or amorphous.
The real space image can be measured with high resolution. further
STM does not damage the sample due to electric current.
It has the advantage of being able to observe with low power and operate in the atmosphere
It is expected to have a wide range of applications.

In STM, a voltage is applied between a metal probe (probe electrode) and a conductive material as a sample, and both are applied to the probe.
Utilizing the fact that when approaching a distance of about nm, a tunnel current flows between them. Since this current responds exponentially to changes in distance between the two, STM is very sensitive to surface conditions. Further, by scanning the probe so as to keep the tunnel current constant, it is possible to read various information regarding all electron clouds in the real space.
At this time, the resolution in the in-plane direction is about 0.1 nm. Therefore, if the principle of STM is applied, it is possible to perform high-density recording and reproduction sufficiently in the atomic order (sub-nanometer).

For example, as a recording layer, a material having a memory effect on voltage-current switching characteristics, for example, a conjugated π
There has been proposed a method of performing recording and reproduction using an STM using a thin film layer of an electronic organic compound or a chalcogen compound (JP-A-63-161552, JP-A-63-163552).
161553). That is, these recording layers
By applying a voltage exceeding the threshold, a transition can be made between two different states depending on the polarity at the time of application, and these states remain stable when no voltage is applied. Then, based on the difference in the tunnel current value when the distance between the surface of the recording layer and the probe is kept constant, it is possible to detect which state is present. Since a voltage exceeding the threshold value can be applied to the recording layer using the probe for detecting the tunnel current, binary recording and reproduction of information can be performed at a recording density corresponding to the in-plane resolution of the STM. . According to this method, if the recording bit size is 10 nm, 10
Large-capacity recording and reproduction of as much as ¹² bits / cm ² are possible.

[0006] Japanese Patent Application Laid-Open No. 1-196751 discloses a technique of forming a plurality of probes on a semiconductor substrate for miniaturization and displacing a recording medium facing the probe in an in-plane direction of the semiconductor substrate to perform recording. The device is shown. For example,
By combining a multi-probe head in which 2500 probes are arranged in a 50 × 50 matrix on a 1 cm square silicon chip and the above-described material having a memory effect, 400 Mbits per probe and a total recording capacity of 1 T (tera) bit Digital data can be recorded and reproduced. In addition, Japanese Patent Application Laid-Open No. 3-503463
The gazette discloses an integrated large-capacity storage device in which a large number of piezoelectric bimorph cantilevers are formed on a silicon substrate to increase the number of channels and improve the processing speed.

In such an information processing apparatus, it is necessary to strictly control the distance between the probe and the recording medium.
In order to reach a target recording bit in an enormous number of recording bits, it is necessary to precisely control the relative position between the probe and the recording medium. Note that such control of the relative position is called tracking.

Heretofore, the distance between the probe and the recording medium has been controlled by bringing the probe and the recording medium close to each other to such an extent that a current (such as a tunnel current or an electric field emission current) flows between the probe and the recording medium. The probe is scanned in the in-plane direction of the recording medium while keeping the flowing state, and the scanning is performed in response to the increase and decrease of the current amount due to the unevenness of the surface of the recording medium and the fluctuation of the electronic state. That is, the detection is performed by detecting a current flowing through the probe, extracting a low-frequency component in the current signal, and driving the probe in the Z direction (normal direction of the recording medium) based on the extraction result. When such control is performed, the low frequency component of the recording information affects the tilt information of the recording medium, so that it is necessary to consider the use of the NRZ method or the like as the recording modulation method, which may reduce the application aspect of the apparatus. Had become.

Although there are few examples in which consideration is given to tracking, see, for example, Japanese Patent Application Laid-Open No. 1-107341.
And JP-A-1-133239 show a method of forming a track groove or embedding a track row on a storage medium in advance, and scanning a probe based on the track groove or track row. I have.

[0010]

As described above, in the conventional information processing apparatus, the distance between the probe and the recording medium is controlled by a low-frequency component of a current such as a tunnel current. There is a problem of being restricted. When tracking is performed using a multi-probe head, there is a method of controlling each of a plurality of probes to a track position on a recording medium.
It is necessary to relatively roughly align the substrate on which the multi-probe head is formed with the substrate on which the recording medium is formed. Conventionally, this relatively rough alignment depends on the processing accuracy of the mechanical system, and by this processing accuracy,
Detailed positioning (positioning with track grooves, etc.)
The control range when performing is determined. For this reason, in order to reduce the time required for the alignment, it is necessary to keep the processing accuracy of the mechanical system high, which has been a factor of increasing the manufacturing cost.

An object of the present invention is to provide a novel mechanism for three-dimensional relative position control between a recording medium and a probe, without restricting a recording modulation method for a recording medium, and for a mechanical system. An object of the present invention is to provide an information processing apparatus that does not need to maintain high processing accuracy.

[0012]

The information processing apparatus of the present invention According to an aspect of the probe facing the record medium, and voltage applying means for applying a voltage between the said recording medium probe, said probe and said recording medium In an information processing apparatus having at least one moving unit that relatively moves and a movement control unit that controls movement by the moving unit, a piezoelectric bimorph that faces the recording medium and supports the probe, wherein the recording medium drive electrodes and the electrostatic capacitance detection only provided on the surface of the side electrode, the electrostatic
The movement control means, comprising: an electrode dedicated to capacitance detection; and capacitance detection means for detecting a capacitance value between the recording medium.
Is based on the output of the capacitance detecting means.
And characterized by controlling the relative position of the over blanking and the recording medium
I do .

[0013]

[Function] When the probe and the recording medium are relatively moved, only the capacitance detection provided on the piezoelectric bimorph is performed.
The capacitance between the electrode and the recording medium changes depending on the distance between the electrode and the recording medium and the unevenness in the in-plane direction of the recording medium or a change in the electronic state. Since the probe relative positional relationship between the electrostatic capacitance detection dedicated electric <br/> electrode and probe are not changed by being supported on a piezoelectric bimorph, by feedback by detecting the electrostatic capacitance value, electrostatic
It is possible to strictly control the relative positional relationship between the electrode dedicated to detecting capacitance and the recording medium, that is, the relative positional relationship between the probe and the recording medium.

For example, when controlling the distance between the probe and the recording medium, the capacitance value is adjusted so that the capacitance value between the electrode dedicated to detecting the capacitance and the recording medium becomes constant. What is necessary is just to feed back to a circuit.
In this case, even if there are irregularities on the surface of the recording medium and changes in the electronic state, the irregularities and changes are averaged to a range of about the size of the electrode dedicated to capacitance detection , and the The capacitance value is measured. Therefore, if the electrode dedicated to detecting the capacitance is made larger than the size of one recording bit, the surface drawn by the tip of the probe during scanning of the probe (hereinafter, referred to as “ the electrode”).
It is possible to detect only the fluctuation due to the inclination between the scanning surface) and the recording medium surface.

Further, if there is any structure on the surface of the recording medium, when the recording medium and the probe are relatively moved in the in-plane direction of the recording medium, the capacitance detected corresponding to the structure is detected. The value will change. For example, if a track groove is formed periodically on the surface of the recording medium, the relative movement is caused by the size of the unevenness of the track groove, the width of the track groove, and the width of the electrode dedicated to capacitance detection on the piezoelectric bimorph side. Thus, as shown in FIG. 8, the detected capacitance value changes periodically. Therefore, when the probe and the recording medium are relatively moved relatively in the in-plane direction, relatively rough positioning can be performed by counting the number of peaks of the change in capacitance. In the case of a multi-probe head configuration, a plurality of capacitance detection
Dedicated electrode provided out, control such as to measure the capacitance signal all of these signals is relatively moved to a position such that the peak value or a predetermined value for each of a plurality of capacitance detection only of the electrode Or by doing
A relatively rough alignment can be performed.

[0016]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an information processing apparatus according to a first embodiment of the present invention, and FIG. 2 is a front view of a cantilever.

The recording medium 100 has a structure in which a lower electrode layer 102 and a recording layer 103 are sequentially laminated on a glass substrate 121, and the XY stage 1 has the glass substrate 121 side down.
It is fixed on 01. For the recording layer 103, the above-described material having the electric memory effect is used.
In the recording layer 103, a track groove 104 extending to the lower electrode layer 102 is formed. Also, the lower electrode layer 1
02, the bias voltage VB1 is applied.

A piezoelectric bimorph type cantilever 106 is provided so as to face the recording medium 100, and a probe electrode 105 facing the recording layer 103 is provided at the free end of the cantilever 106.
The probe electrode 105 has a very sharp tip, detects a tunnel current flowing between the probe layer 105 and the recording layer 103, and applies a voltage to the recording layer 103 to cause an electric memory effect. The cantilever 106 is for supporting and driving the probe electrode 105. The dimensions of the cantilever 106 are, for example, 340 μm in length,
The width is 50 μm and the pressure is 15 μm.

As shown in FIG. 2, the cantilever 106 has a bimorph drive electrode 1 in addition to the probe electrode 105.
17. A detection electrode 113 is provided in proximity to the probe electrode 105 and used for detecting capacitance. The detection electrodes 113 are substantially 3
It has a square shape, and the size is set to be larger than the size of the recording bit of the recording medium 100. Also,
Wirings 105 a and 113 a provided on the surface of the cantilever 106 are connected to the probe electrode 105 and the detection electrode 113. Here, for simplicity, cantilever 1
The structure supporting the 06 and the bonding of wiring are omitted.

The probe electrode 105 is connected to the cantilever 10.
6, the current-voltage conversion amplifier 10
7 is connected. An output of the current-voltage conversion amplifier 107 is connected to inputs of a high-pass filter 108 and an edge detection comparator 110, respectively. The output of the high-pass filter 108 is input to a comparator 109, and the output of the comparator 109 is a data modem 111
Is being entered. The reference voltage VB2, which is a threshold voltage for edge detection, is further input to the edge detection comparator 110.

The data modulator / demodulator 111 generates modulated data according to data to be recorded on the recording medium, demodulates the modulated data input from the comparator 109, and outputs the demodulated data as a reproduced signal. The modulated data output from the data modulator 111 is sent to the pulse generator 11 via the recording controller 124.
2, the output of the pulse generator 112 is added to the bias voltage VB1 and applied to the lower electrode layer 102.

Detection electrode 113 on cantilever 106
Is connected to the input side of the capacitance detection circuit 114 via the wiring 113a. The capacitance detection circuit 114 has a known configuration for detecting the capacitance between the detection electrode 113 and the recording medium 100. Capacitance detection circuit 11
4 is input to the error amplifier 115. The bias voltage VB3 is also input to the error amplifier 115. The output of the error amplifier 115 is connected to the drive electrode 117 of the cantilever 106 via the gain amplifier 116.

Further, the in-plane direction (XY
Tracking control unit 11 for controlling the position of
8 are provided. The tracking control section 118 outputs a status signal, an up control signal, a down control signal, and a wobbling signal.
The status signal is input to the AND circuit 131 together with the output of the edge detection comparator 110, and the up control signal is output to the OR circuit 13 together with the output of the AND circuit 131.
Enter 2 An up / down counter 119 is provided, and up / down control of the up / down counter 119 is performed by an output of the OR circuit 132 and a down control signal. That is, the output of the OR circuit 132 is connected to the up input unit of the up / down counter 119, and the down control signal is input to the down input terminal. On the output side of the up / down counter 119, D / A (digital / analog)
A converter 120 is provided, and the output of the D / A converter 120 is input to the drive amplifier 123 in the X direction. The output of the drive amplifier 123 is connected to the input terminal of the XY stage 101 in the X direction. On the other hand, the tracking controller 1
The wobbling signal from the drive amplifier 122 is input to the drive amplifier 122 in the Y direction via the resistor R1.
Is connected to the input terminal in the Y direction of the XY stage. Further, a variable resistor VR1 that connects between the inputs of both drive amplifiers 122 and 123 is provided.

Next, the operation of the information recording apparatus will be described. First, control of the distance between the probe 105 and the recording medium 100 will be described. This control is performed when the probe electrode 105 and the recording medium 100 are relatively moved in the in-plane direction of the recording medium 100.
The distance between the recording medium 1 and the recording medium 100 is kept constant.
00 is a control for correcting the inclination of the surface.

The output of the capacitance detecting circuit 114 is compared with a reference voltage VB3 by an error amplifier 115, and the error component of this comparison is amplified by a gain amplifier 116 and fed back to a drive electrode 117 of a piezoelectric bimorph cantilever 106. You. At this time, when the capacitance value decreases, control is performed such that the cantilever 106 bends toward the recording medium 100, so that the distance between the lower electrode layer 102 and the detection electrode 113 becomes smaller than the detection accuracy of the capacitance. It will be kept constant within the range. As a result, the distance between the probe 105 on the cantilever 106 and the surface of the recording medium 100 is kept constant. In order to adjust this distance, the reference voltage VB3 may be appropriately changed.

Next, the operation at the time of recording will be described. As shown in FIG. 3, the recording medium 100 is two-dimensionally scanned by the probe electrode 105 (control for this scanning will be described later). While performing this scan,
In response to a command from the recording control unit 124, for example, a write pulse is generated from the pulse generator 112 at a position corresponding to recording "1" in binary recording, and no writing pulse is generated at a position corresponding to recording "0". To do. as a result,
The voltage is applied to the recording layer 103 only at the position corresponding to the recording “1”, and the recording layer 1 is applied by the electric memory effect.
The electronic state of 03 changes, and recording is performed.

Next, the operation at the time of reproduction will be described. At the time of reproduction, since the bias voltage VB1 is applied between the recording medium 100 and the probe electrode 105, a tunnel current flows between the recording medium 100 and the probe electrode 105. Here, when the probe electrode 105 is two-dimensionally scanned in the same manner as at the time of recording, the value of the tunnel current changes according to the information recorded on the recording medium 100. The tunnel current flowing through the probe electrode 105 is converted and amplified into a voltage signal by the current-voltage conversion amplifier 107, and a high-frequency component, that is, a data information component is extracted by the high-pass filter 108. And comparator 1
In step 09, the data is compared with a threshold voltage, converted into binary data, and input to the data modulation / demodulation unit 111.

Next, two-dimensional scanning of the probe electrode 105 and position control in the in-plane direction will be described. In this embodiment, the probe electrode 1 in the in-plane direction of the recording medium 100 is used.
The two-dimensional scanning of 05 is performed by driving the recording medium 100 on the XY stage 101 in each of the XY directions. Here, it is assumed that recording and reproduction are performed at the time of scanning in the forward direction in the reciprocating scanning in the X direction. When the probe electrode 105 needs to move between tracks, it is assumed that the probe electrode 105 moves across the tracks during the backward movement in the X direction. Further, when an edge portion of the recording medium 100 is detected during scanning, the scanning direction is reversed to thereby detect the probe 105.
Is not detached from the recording medium 100. First, an operation for detecting an edge portion of the recording medium 100 will be described.

As described above, the current-voltage conversion amplifier 107
Outputs a voltage signal corresponding to the tunnel current value, and this voltage signal is input to the edge detection comparator 110. If the probe electrode 105 reaches the edge portion of the recording medium 100, the tunnel current decreases sharply, so that the voltage signal also sharply decreases. The edge detection comparator 110 detects that the probe electrode 105 has reached the edge position by comparing the reference voltage VB2, which is a threshold voltage, with this voltage signal. Here, a signal indicating that the edge position has been detected is called an edge detection signal.

On the other hand, the status signal is a signal which becomes "1" during recording or reproduction. Therefore, when an edge detection signal is generated at the time of recording / reproduction, the output of the AND circuit 131 becomes "1", so that the up / down counter 119 is forcibly switched to the up counter operation, and the up / down counter 1 is driven to a certain count value.
When 19 counts up, the up / down counter 1
19 switches to a down counter operation. The up / down counter 119 has a tracking control unit 118.
Since the down control signal is also input, the tracking control unit 118 can also control the up / down of the up / down counter 119.

The count output of the up / down counter 119 is converted into an analog signal by the D / A converter 120, whereby the XY stage 101 is driven in the X direction by ΔX. Further, the output of the D / A converter 120 is combined with the wobbling signal input via the resistor R1 via the variable resistor VR1. The combined signal drives the XY stage 101 by ΔY in the Y direction. By the above operation, as shown in FIG. 3, two-dimensional scanning of the recording medium 100 by the probe electrode 105 is performed. The scanning azimuth of the probe electrode 105 is performed by changing the variable resistor VR1 according to the scanning azimuth control signal and changing the drive ratio of ΔX / ΔY of the XY stage. In order to detect the scanning azimuth so as to trace the recording bit string properly, the wobbling voltage is driven by ΔY, and the envelope signal of the tunnel current (voltage) signal at this time may be monitored.

Note that the probe electrode 105 is
04, an edge detection signal is also output. However, the probe electrode 105 moves so as to cross the track groove 104 except at the time of recording / reproduction.
At this time, the status signal is "0". Therefore, even if an edge detection signal derived from the track groove 104 is generated, the up / down counter 119 does not forcibly transition to the up counter operation, and the scanning direction does not change due to the existence of the track groove 104.

Next, a second embodiment of the present invention will be described. FIG. 4 is a block diagram showing the configuration of the information processing apparatus according to the second embodiment, and FIG. 5 is a front view of the cantilever.

The recording medium 200 has a structure in which a lower electrode layer 202 and a recording layer 203 are sequentially laminated on a glass substrate 222, and the coarse movement mechanism 226 is arranged with the glass substrate 222 side down.
Is fixed on top. For the recording layer 203, the above-described material having the electric memory effect is used. The track groove 104 is formed in the recording layer 203 until reaching the lower electrode layer 202. Also, the lower electrode layer 202
, A bias voltage VB1 is applied. The coarse movement mechanism 226 moves the recording medium 200 in the XY directions, that is, the in-plane direction of the recording medium 200, and
This is for rotating in the Y plane.

A multi-probe head 250 is provided facing the recording medium 200. The multi-probe head 250 is provided with a plurality of piezoelectric bimorph-type cantilevers 206.
The Y stage 201 allows fine movement in the XY directions. At the tip of the free end of each cantilever 206, a probe electrode 205 facing the recording layer 203 is provided. The probe electrode 205 has an extremely sharp tip, detects a tunnel current flowing between the probe layer 205 and the recording layer 203, and applies a voltage to the recording layer 103 to cause an electric memory effect. The cantilever 206 is for supporting and driving the probe electrode 205. The dimensions of the cantilever 206 are, for example, a length of 340 μm, a width of 50 μm, and a pressure of 15 μm.

As shown in FIG. 5, a bimorph drive electrode 2 is provided on the cantilever 206 in addition to the probe electrode 205.
29, a detection electrode 213 is provided in proximity to the probe electrode 205 and used for detecting capacitance. The detection electrode 213 has a substantially linear shape formed as a planar pattern, and its extending direction is
It is substantially parallel to the direction in which the upper track groove 204 extends. The probe electrode 205 has a cantilever 2
The wiring 205a provided on the 06 surface is connected. Here, for the sake of simplicity, the structure supporting the cantilever 206 and the bonding of the wiring are omitted. Here, as shown in FIG. 6, it is assumed that a total of 25 cantilevers 206 are formed in 5 rows and 5 columns.

Here, the track groove 2 on the recording medium 200
The arrangement of No. 04 will be described. As described above, the cantilevers 206 are formed in a 5-row, 5-column array, but a total of five track grooves 204 are provided corresponding to each column of the array of the cantilevers 206. Here, each row of the array of cantilevers 206 refers to five cantilevers arranged in the X direction in the figure. Each track groove 204 has a comb-shaped planar arrangement, and the interval between the teeth of the comb matches the interval between the cantilevers 206 belonging to each row. Also,
The distance between the track grooves 204 is determined by the cantilever 206.
In the row direction (Y direction in the figure). By forming the track groove 204 in this way, if the recording medium 200 and the multi-probe head 250 are properly aligned, the distance between each cantilever 206 and the track groove 204 is all the same.

The probe electrode 205 is connected to the cantilever 20.
6, the current-voltage conversion amplifier 20
7 is connected. The output of the current / voltage conversion amplifier 207 is output from the high-pass filter 208 and the low-pass filter 216.
And the input of the edge detection comparator 210. The output of the high-pass filter 208 is input to the comparator 209, and the output of the comparator 209 is input to the data modem 211. The reference voltage VB2 serving as a threshold voltage for edge detection is further input to the edge detection comparator 210.

The data modulator / demodulator 211 generates modulated data according to data to be recorded on the recording medium, demodulates the modulated data input from the comparator 209, and outputs the demodulated data as a reproduced signal. The modulated data output from the data modulator 211 is sent to the pulse generator 21 via the recording controller 225.
2, the output of the pulse generator 212 is added to the bias voltage VB1 and applied to the lower electrode layer 202.

The output of the low-pass filter 216 is input to a differential amplifier 217 to which an offset voltage is input, and the output of the differential amplifier 217 is connected to the input of a sample and hold circuit 218. The output of the sample and hold circuit 218 is connected to the drive electrode 229 of the cantilever 206 via the amplifier 227.

Detection electrode 213 on each cantilever 206
Is connected to the input side of the capacitance detection circuit 214 via a wiring. The capacitance detection circuit 214 detects the detection electrode 2
It has a known configuration for detecting the capacitance between the recording medium 200 and the recording medium 200, and is provided for each detection electrode 213. Then, an arithmetic circuit 215 is provided, and the outputs of all the capacitance detecting circuits 214 corresponding to the respective cantilevers 206 are input to the arithmetic circuit 215.

Further, the in-plane direction (XY
Tracking control unit 21 for controlling the position of
9 are provided. The tracking control section 219 outputs a status signal, an up control signal, a down control signal, and a wobbling signal.
The status signal is input to the AND circuit 231 together with the output of the edge detection comparator 210, and the up control signal is input to the OR circuit 23 together with the output of the AND circuit 231.
Enter 2 An up / down counter 220 is provided, and up / down control of the up / down counter 220 is performed by an output of the OR circuit 232 and a down control signal. A D / A (digital / analog) converter 221 is provided on the output side of the up / down counter 220, and the output of the D / A converter 221 is input to the drive amplifier 224 in the X direction. The output of the drive amplifier 224 is connected to the input terminal of the XY stage 201 in the X direction. On the other hand, the wobbling signal from the tracking controller 219 is input to the drive amplifier 223 in the Y direction via the resistor R1.
The output of 23 is connected to the input terminal of the XY stage 201 in the Y direction. Then, both drive amplifiers 223,
A variable resistor VR1 that connects between 224 inputs is provided.

Next, the operation of the information processing apparatus will be described. First, control of the distance between the probe electrode 205 and the recording medium 200 will be described.

Normally, the bias voltage VB1 applied to the lower electrode layer 202 is about 100 mV. The bias voltage V is applied between the probe electrode 205 and the recording medium 200.
The cantilever 206 is controlled to approach the two until B1 is applied and a current of about 2 nA flows between them. The current (mainly the tunnel current) flowing through the probe electrode 205 is converted into a voltage signal by the current-voltage conversion amplifier 207 and passes through the low-pass filter 216.
As a result, a low-frequency to direct-current component, that is, a component including information such as the inclination of the surface of the recording medium 200, is extracted from the tunnel current signal. In this case, the low-pass filter 216
Is set to about the scanning frequency of the probe electrode 205 described later. The output of the low-pass filter 216 is input to the differential amplifier 217, compared with the offset voltage, and the difference is output from the differential amplifier 217 to the sample and hold circuit 218. Then, the output of the sample hold circuit 218 is fed back to the drive electrode 229 of the cantilever 206 via the amplifier 227. As a result, even if the recording medium 200 is tilted,
The distance between the probe electrode 205 and the recording medium 200 is kept constant on average on the value determined by the offset voltage. By providing the sample and hold circuit 218, the distance between the two can be kept stable even during recording in which a pulse voltage for recording is applied to the recording medium 200.

Next, the operation during recording and during reproduction will be described. The recording / reproducing operation of this embodiment is the same as that of the first embodiment. When recording is performed, a write pulse is generated by the pulse generator 212 according to a command from the recording control unit 225 while scanning the recording medium 200 with the probe electrode 205, and the recording layer 2 is scanned.
03 is applied with a voltage corresponding to the recording signal. For reproduction, while scanning the recording medium 200 with the probe electrode 205, a tunnel current flowing through the probe electrode 205 is detected by the current-voltage conversion amplifier 207, and a high-frequency component, that is, a data information component is extracted by the high-pass filter 208. This is performed by comparing with a threshold voltage by a comparator 209 and binarizing it.

Next, two-dimensional scanning of the probe electrode 205 and position control in the in-plane direction will be described. First, a description will be given of control of a relatively rough position between the multi-probe head 250 and the recording medium 200.

First, the multi-probe head 25 is moved to such an extent that the capacitance can be detected by each detection electrode 213.
The distance between 0 and the recording medium 200 is reduced. Then, the recording medium 200 is vibrated in the X direction by the coarse movement mechanism 226, and the position where the negative peak of the capacitance change is detected from all the detection electrodes 213 corresponding to the cantilever 206 in the first row shown in FIG. Is stopped, and the recording medium 200 is stopped at a position several μm before this position (FIG. 7A). Since both the track groove 204 and the detection electrode 213 extend in the row direction, that is, the Y direction, this operation is completed only by moving the storage medium 200 in the X direction. By performing this operation, rough alignment in the X direction is completed.

Next, the recording medium 20 is moved by the coarse movement mechanism 226.
0 is oscillated in the Y direction, a search is made for a position where the negative peak of the capacitance change is detected from all of the detection electrodes 213 corresponding to the cantilever 206 in the first row shown in FIG. The recording medium 200 is stopped at the position (FIG. 7B). By the operation up to this point, the approximate positioning of each cantilever 206 and the corresponding track groove 204 has been completed except for the rotational component in the XY plane.

Then, the recording medium 200 is again oscillated in the X direction by the coarse movement mechanism 226, and the capacitance change detected by the detection electrode 213 of each cantilever 206 in the first row and the first column and the fifth row and the first column is calculated as follows. The coarse movement mechanism 226 controls the recording medium 20 so that peaks are detected at the same time.
0 is rotated in the θ direction. By the above operation, the relative rough positioning of each track groove 204 and each cantilever 206 is completed (FIG. 7C).

In this state, the multi-probe head 250
The above-described recording operation and reproduction operation may be performed by reducing the distance between the probe electrode 205 and the recording medium 200 so that the tunnel current can be detected from each probe electrode 205.

Next, detailed position control of the probe electrode 205 in the in-plane direction of the recording medium 200 will be described. In this embodiment, the two-dimensional scanning of the probe electrode 205 in the in-plane direction of the recording medium 200 is performed by driving the relatively roughly aligned cantilever 206 on the XY stage 201 in each of the XY directions. It is. In this embodiment, unlike the first embodiment described above, X
Although the Y stage 201 is provided on the cantilever 206 side, the basic operation of the position control is the same as that of the first embodiment. Here, of the reciprocating scanning in the X direction,
It is assumed that recording and reproduction are performed during forward scanning. First, an operation for detecting an edge portion of the recording medium 200 will be described.

A voltage signal corresponding to the tunnel current value is output from the current-voltage conversion amplifier 207, and this voltage signal is input to the edge detection comparator 210. If the probe electrode 205 approaches the edge of the recording medium 200, the voltage signal corresponding to the tunnel current also decreases sharply.
Detects that the probe electrode 205 has reached the edge position by comparing with a reference voltage VB2 which is a threshold voltage, and outputs an edge detection signal.

When an edge detection signal is generated during recording / reproducing, the status signal is "1" and the AND circuit 23
When the output of 1 becomes "1", the up / down counter 220 is forcibly switched to the up counter operation, and when it counts up to a certain count value, the up / down counter 220 is switched to the down counter operation. The up / down counter 220 is also controlled to be up / down by a signal from the tracking control unit 219.

The count output of the up / down counter 220 is converted into an analog signal by the D / A converter 221, whereby the XY stage 201 is driven in the X direction by ΔX. Further, the output of the D / A converter 221 is combined with the wobbling signal input via the resistor R1 via the variable resistor VR1. The XY stage 221 is driven by ΔY in the Y direction by the synthesized signal. By the above operation, as shown in FIG.
It is driven two-dimensionally and two-dimensional scanning is performed. This scanning azimuth is performed by changing the variable resistor VR1 by the scanning azimuth control signal and changing the drive ratio of ΔX / ΔY. In order to detect the scanning azimuth so as to trace the recording bit string properly, the wobbling voltage is driven by ΔY, and the envelope signal of the tunnel current (voltage) signal at this time may be monitored.

It should be noted that the probe electrode 205 is
04, an edge detection signal is also output. At this time, since the status signal is "0", even if an edge detection signal derived from the track groove 204 is generated, the up / down counter 220 does not operate. There is no forcible transition to the up-counter operation.
The scanning direction does not change due to the presence of 04.

In this embodiment, both the track pattern used for relatively rough positioning and the tracking pattern used for relatively detailed positioning are used as the track grooves 204. The number can be reduced. Of course, it is also possible to separately provide a tracking pattern used for relatively rough positioning and a tracking pattern used for relatively detailed position control on a recording medium.

[0057]

As described above, the present invention is directed to the detection of the capacitance formed on the surface of the piezoelectric bimorph on the recording medium side.
And the electrode, the electrostatic capacitance of the provision of the electrostatic capacitance detecting means for detecting an electrostatic capacitance value between the electrostatic capacitance detection only of the electrode and the recording medium, and the electrostatic capacitance detection only of the electrode and the recording medium It is possible to control the relative position between the probe and the recording medium based on the value and its change, and there is no restriction on the recording modulation method on the recording medium, and it is possible to improve the transfer speed, and There is an effect that the demand for machining accuracy of the mechanical system can be reduced, the cost can be suppressed, and mass production can be easily performed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an information processing apparatus according to a first embodiment of this invention.

FIG. 2 is a front view of a cantilever in the apparatus of FIG.

FIG. 3 is a diagram illustrating area scanning.

FIG. 4 is a block diagram illustrating a configuration of an information processing apparatus according to a second embodiment of the present invention.

FIG. 5 is a front view of a cantilever in the apparatus of FIG.

FIG. 6 is a diagram illustrating an arrangement of cantilevers on a multi-probe head in the apparatus of FIG.

FIGS. 7A to 7C are schematic diagrams showing a relative positional relationship between a multi-probe head and a track groove in the apparatus of FIG.

FIG. 8 is a characteristic diagram showing a change in capacitance when a recording medium and a probe move relatively.

[Explanation of symbols]

 100, 200 Recording medium 101, 201 XY stage 102, 202 Lower electrode layer 103, 203 Recording layer 104, 204 Track groove 105, 205 Probe electrode 106, 206 Cantilever 107, 207 Current-voltage conversion amplifier 108, 208 High-pass filter 109 , 209 Comparator 110,210 Edge detection comparator 111,211 Data modem 112,212 Pulse generator 113,213 Detection electrode 114,214 Capacitance detection circuit 115,217 Error amplifier 117,229 Drive electrode 118,219 Tracking control Unit 119,220 Up / down counter 120,221 D / A converter 121,222 Glass substrate 124,225 Recording control unit 215 Operation circuit 216 Low-pass filter 218 Sample hold circuit 226 Coarse movement mechanism 227 amplifier 250 multi-probe head

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shunichi Shido 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Katsunori Hatana 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (56) References JP-A-6-76373 (JP, A) JP-A-5-109131 (JP, A) JP-A-5-250734 (JP, A) JP-A-2-123541 (JP, A) A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G11B 9/14

Claims (7)

(57) [Claims] A probe opposed to 1. A Symbol recording medium, and voltage applying means for applying a voltage between the said recording medium probe and at least one moving means for relatively moving said probe and said recording medium, An information processing apparatus comprising: movement control means for controlling movement by the movement means; a piezoelectric bimorph facing the recording medium and supporting the probe; and a piezoelectric bimorph provided on a surface of the piezoelectric bimorph on the recording medium side.
Comprising a drive electrode and an electrostatic capacitance detection only of the electrode, and a capacitance detection means for detecting an electrostatic capacitance value between the capacitance detection only of the electrode and the recording medium, wherein the movement control means Based on the output of the capacitance detection means
And controlling a relative position between the probe and the recording medium . 2. The probe and a piezoelectric bar supporting the probe.
A plurality of sets of immorphs are provided, and the electrodes dedicated to capacitance detection are provided on each piezoelectric bimorph.
The information processing apparatus according to claim 1 that. 3. The information processing apparatus according to claim 1 , wherein said movement control means controls a distance between said probe and said recording medium. 4. The size of the electrode dedicated to capacitance detection is as follows :
Larger than the size of one recording bit on the recording medium
The information processing apparatus according to claim 3, wherein: Wherein said movement control means, according to claim 1 or 2, characterized in that <br/> controlling the relative position between said probe and said recording medium in the plane direction of the recording medium Information processing device. 6. The information processing apparatus according to claim 5, wherein a tracking pattern is formed on the recording medium. 7. that the electrostatic capacitance detection only of the electrode has a shape extending in a longitudinal direction of said tracking pattern
The information processing apparatus according to claim 6, wherein