CA2070948C - Information reproduction by high density scanning - Google Patents
Information reproduction by high density scanningInfo
- Publication number
- CA2070948C CA2070948C CA002070948A CA2070948A CA2070948C CA 2070948 C CA2070948 C CA 2070948C CA 002070948 A CA002070948 A CA 002070948A CA 2070948 A CA2070948 A CA 2070948A CA 2070948 C CA2070948 C CA 2070948C
- Authority
- CA
- Canada
- Prior art keywords
- information
- recording medium
- probe electrode
- recorded
- scanning
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B9/00—Recording or reproducing using a method not covered by one of the main groups G11B3/00 - G11B7/00; Record carriers therefor
- G11B9/12—Recording or reproducing using a method not covered by one of the main groups G11B3/00 - G11B7/00; Record carriers therefor using near-field interactions; Record carriers therefor
- G11B9/14—Recording or reproducing using a method not covered by one of the main groups G11B3/00 - G11B7/00; Record carriers therefor using near-field interactions; Record carriers therefor using microscopic probe means, i.e. recording or reproducing by means directly associated with the tip of a microscopic electrical probe as used in Scanning Tunneling Microscopy [STM] or Atomic Force Microscopy [AFM] for inducing physical or electrical perturbations in a recording medium; Record carriers or media specially adapted for such transducing of information
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y10/00—Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S977/00—Nanotechnology
- Y10S977/84—Manufacture, treatment, or detection of nanostructure
- Y10S977/849—Manufacture, treatment, or detection of nanostructure with scanning probe
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S977/00—Nanotechnology
- Y10S977/84—Manufacture, treatment, or detection of nanostructure
- Y10S977/849—Manufacture, treatment, or detection of nanostructure with scanning probe
- Y10S977/86—Scanning probe structure
- Y10S977/861—Scanning tunneling probe
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S977/00—Nanotechnology
- Y10S977/84—Manufacture, treatment, or detection of nanostructure
- Y10S977/88—Manufacture, treatment, or detection of nanostructure with arrangement, process, or apparatus for testing
- Y10S977/881—Microscopy or spectroscopy, e.g. sem, tem
Abstract
In a reproducing operation, scanning information is detected while scanning an information string with a probe such that a density of the scan lines is higher than a density of the recorded information, and a logical-sum signal of the plurality of scanning information is used as a reproduced signal. It is thereby possible to prevent deterioration during information processing of the S/N ratio and the like produced due to a positional error of a recording-medium control mechanism caused by various factors.
Description
2~7~8 TITLE OF THE INVENI'ION
INFO~MATION REP~ODUCING NETHOD AND
IN~O~M~TION ~EPRODUCING APPARATUS WHICH USES THE METHOD
BACKG~OUND OF THE INVENTION
Field of the Invention This invention relates to the technical field of high-density and large-capacity memory devices which use, for ex-ample, the principle of a scanning tunneling microscope (hereinafter termed an STM).
Description of -the Prior Art Heretofore, semiconductor memories comprising semicon-ductors and magnetic memories comprising magnetic materials have been mainly used as memories. Recently, however, in ac-cordance with the development of laser techniques, inexpen-sive high-density recording media comprising optical memories which use organic thin films made of organic dyes, photopolymers or the like have appeared.
In addition, STM's which can directly observe the electronic ~tructure of surface atoms of a conductor have been developed (G. Binnig et al. Phys. Rev. Lett. 49, 57 (1982)). The STM has the advantages that a real-space image 2~7~4~
of a material, irrespective of crystal:Line or amorphous, can be measured with high resolution, a sample can be observed at low power without damaging it by current, and since the apparatus operates even in air, it can therefore be used for ~arious ma-terials. Accordingly, a wide range of applica-tions is expected. The STM utilizes the phenomenon that a tunnel current flows when a metal probe (probe electrode) and a conductive substance are brought as close as about 1 nm (nanometer) while applying a voltage between them. The tunnel current is very sensitive to a change in the distance between the probe and the substanceO By scanning tbe probe so as to maintain the tunnel current at a constant value, it is even possible to read various kinds O:e information with respect to the entire electronic cloud of a real space. At that time, resolution in the direction of the plane of the substance is about 0.1 nm.
Accordingly, by applying the principle of the STM, it is possible to sufficiently record and reproduce high-density data in the atomic order (in the order of sub-nanometers). For example, in a recording/reproducing ap-paratus disclosed in Japanese Patent Application Public Dis-closure (Kokai) No. 61-80536 (1986), a writing operation is per~ormed while removing atomic particles adsorbed on the surface of a medium using an elec-tronic beam or -the like, and the writ-ten data is reproduced using an S'l'M.
~7~9gL8 Methods exist in which an STM performs recording and reproducing opera-tions using a thin-film recording layer of a material having a memory effect with respect to voltage-current switching characteris-tics. Examples of recording layer materials include a ~-electron-type organic compound, a chalcogenide compound or the like, and are disclosed, for example, in Japanese Patent Application Public Disclosures (Kokai) Nos. 63-161552 (1988) and 63-161553 (1988). Accord-ing to such methods, large-capacity recording and reproduc-ing operations on the order of 101~ bits/cm~ become possibleassuming the size of recording bits of 10 nms.
In using such recording/reproducing methods, in order to reproduce data with an excellerlt S/N ratio, it is in general necessary to perform so~called tracking ~ontrol wherein a probe electrode is moved along a recorded si~nal string while performing feedback control, since recording bits are very small. For example, a method has been proposed in Japanese Patent Application Public Disclosure (Kokai) No.
1-107341 l1989) wherein a V-shaped groove is previously formed on the sur~ace o~ a recording medium, and a probe electrode is controlled so as to be always situa$ed in the center of the groove. On the other hand, methods which do not require a -tracking operation have been proposed. For ex-ample, a method is disclosed in Japanese Patent Application 25 Public Disclosure (Kokai) No. 2-50333 (1990), wherein, in a 207~9~
reproducing opera-tion~ information is read by scanning a re-corded signal string with a probe electrode with a density higher than the recording density without performing a tracking operation, and recorded information is reproduced using a pattern recognition technique.
However, control is complicated in the above-described methods which use a tracki.ng operation, and a complicated pattern recognition process requiring a long processing time is necessary in -the above-described method which uses pat-tern recognition without using a tracking operation.
SUMMARY OF THE INVENTION
It is an object of the presen-t invention to provide a method and apparatus which can easily reproduce information without performin~ a tracking operation.
In a method of reproducing information by scanning a recorded signal s-tring with a probe with a density higher than the recording density in a reproducing operation, by using a logical-sum signal of a plurality of scanning infor-mation strings as a reproducing signal, it is possible to prevent deteriora-tion in the S/N ratio and the like produced by a posi-tional error of a recording-medium control mechanism caused by various fac-tors in information process-ing.
2~7~8 BRIEF DESCRIPTION OF THE DRAWINGS
FI~. 1 is a diagram showing a recording/reproducing ap-paratus according to an embodiment oi' the present invention;
5FIGS. 2(a) and 2(b) are diagrams illustrating the scan-ning method of a reading system for scanning recorded signals;
FIGS. 3(1~ and 3(2) are diagrams illustrating reproduced information obtained by the scanning method shown in FIG. 2;
FIG. 4 is a diagram showing -the waveform of a write pulse voltage;
FIG. 5 is a diagram showing th,~ waveform of an erase pulse voltage;
15FIGS. 6(a) and 6(b) are diagrams illustrating the scan-nin~ method of a reading syst~m ~or record~d signals in a second embodiment o~ the present invention; and FIGS. 7(1) and 7(2) are di.agrams illustrating reproduced information obtained by the scanning method shown in FIG. 6.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 is a block diagram showing the entire configura-tion o~ an information recording/reproducing apparatus ac-~07~9~
cording to an embodiment of the present invention. In FIG.1, a tungsten needle is used as a probe electrode 1. In or-der to increase resolution in recording and reproducing operations, the front end of the tungsten needle is sharply processed by mechanical polishing, electropolishing or the like. Pt-Ir, Pt or the like may also be used as the material for the probe electrode 1, and the processing method is not limited to the above-described methods. A recording medium 2 comprises a material having the property of switching be-tween states which have different conductivities, that is,a memory switching property in the current-voltage charac-teristic. In -the present embodiment, the recording medium 2 is provided by accumulating eight layers of' SOAZ
(squalirium-bis-6-octyl azulene) on a graphite substrate using the LB (Langmuir-Blodge$t) method. A current amplifier 3 converts a current (tunnel current) flowing in the probe electrode 1 into a voltage and amplif'ies the converted volt-age. A fine-movement mechanism 4 includes cylindrical piezoelectric elements, and finely moves the probe electrode l in the direction of the plane of the recording medium 2 (X
and Y directions) and in the direction to control the amount of space between the recording medium 2 ~nd the probe electrode 1 (Z direction3. A coar~e-movement mechanism 5 in-clude~ parallel springs comprising elastic hinges, and holds and coarsely moves the recording medium 2 in the X and Y
2~709~8 directions. An XYZ controller 6 controls the fine-movement mechanism 4 and -the coarse-movement mechanism 5 by providing them wi-th control voltages. A control arithmetic circuit 7 modulates and demodulates data while controlling the respec-tive units. A voltage applica$ion circuit 8 can app:ly an ar-bitrary voltage between - 10 V (volts) and + 10 V between the probe electrode 1 and the recording medium 2. The volt-age application circuit 8 applies a pulse-like voltage having a value corresponding to the recorded value in recording and erasing operations, and applies a constan-t bias voltage in a reproducing operation. A field memory 9 temporarily stores data read in a reproducing operation. An arithmetic circuit 10 performs logical calculation of infor-mation stored in the ~ield memory 9.
ExamPle 1 As an example of recording and reproducing information using the apparatus having the above-described configura-tion, an explanation will be provided o~ a case wherein recording and reproducing operations are performed ~sing bi-nary values, i~e., 0 (OFF) and 1 (ON). FIG 2 is a schema-tic diagram showing reference-position patterns and recorded signal regions on the recording medium 2. In FIG. 2, line (1) represents a ~irst recorded line, and line (2) repre-sents a second recorded line. Five recording bits are formed on each of the recorded lines. As depicted in FIG. 2(b), a 2~70~
bit indicated oy a broken circle represents a O (OFF) state, and a bit indicated by a solid circle represents a 1 (ON) state.
When recording information using an apparatus having the configuration shown in FIG. 1, care must be taken so as not to produce crosstalk between lines influenced by ac-curacy in the piezoelectric elemen-ts o~ the fine-movement mechanism 4 for driving the probe electrode 1. Accordingly, a recording operation is performed while scanning the probe electrode 1 along the lines (1) and (2) so that the interval D between the lines ~1) and (2~ satisfies the condition of D
> 2 x L/tan ~, where ~ represents the maximum angular error estimated to occur during a reproducing operation, and I.
represents the length o~ one line.
In a recordin8 operation, the space between the record-ing medium 2 and the probe electrode 1 is subjected to feed-back control so that the current between the recording medium 2 and the probe electrode 1 is about 1 pA
(picoampere). The recording medium 2 is scanned with the probe electrode 1 in a predetermined scanning direction using the fine-movement mechanism 4 while maintaining the above-described space between the recording medium 2 and the probe electrode 1. The probe electrode 1 is stopped at the position of prede-ter~lined X and Y coordinates where informa-tion "1" is to be recorded, and the position in the Z direc-2~7~9~8 g tion is fixed. When the distance between the recordingmedium 2 and the probe electrode 1 has been fixed~ a record-ing operation is perEormed by applying a voltage ~write pulse voltage) having the shape of a triangular-wave pulse shown in FIG. 4. When information to be recorded is 0, an erasing operation (0 recording) is performed by applying a voltage (erase pulse voltage) having the shape of a triangular-wave pulse shown in FIG. 5. Such operations are performed for respective recording positions, and the recording operation is terminated.
Next, an explanation will be provided of operations performed when the information on the recording medium 2 which was recorded in the above-described manner is to be reproduced. Data is recorded in respective recorded segments on the recording medium 2 as differences in conductivity.
Hence, determination of OFF or ON i~ performed according to a difference in conductivity. More specifically, in FIG. 1, a constant bias voltage is applied between the probe electrode 1 and the recording medium 2 while scanning the recording medium 2 with the probe electrode 1 by means of the fine-movement mechanism 4, and data is read according -to the value of a tunnel current flowing in accordance with the conductivity of each segment.
In the present invention, in order -to reproduce only inEormation recorded on each line using a scanning density 2~7~8 -- 10 -- , higher -than the recording density in a writing operation, scannin~ is performed so as to cover a region where informa-tion for one line has been recorded, with a scanning inter-val smaller than the size of the recorded bits, i.e., half the size in the present embodiment, as shown in FIG. 2. Six scanning operations, as indica-ted by An, Bn, Cn, Dn, En and Fn (n - 1, 2, ) shown in FIG. 2j are performed for read-ing the recorded information on each line. FIG. 2 shows a state wherein the direction o-f reproducing scanning is in-clined by an angle 0 relative to the recorded lines (1) and(2).
Respective bits on the respective lines An, Bn, Cn, Dn, En and Fn shown in FIGS. 3(1) and 3(2) represent the states of data read in the six respective scanning operations. Al-though the contents of the data may differ in accordancewith the above-described angle ~ of inclination, if a bit comprises 1 (ON), a recorded 1 (ON) must be contained in at least one of the columns representing respective bits in the vertical direction in the data corresponding to the bit on the lines An - Fn shown in FIG. 3(1) and 3(2). If a]l of the bits in the vertical direction are 0 (OFF), the correspond-ing bit comprises 0 (OFF). Accordingly, by calculating the logical sum of respective bits in the vertical direction at each bit position on the lines An Fn, recorded information can be reproduced as represented by Gn shown in FIGS. 3(1) 2~7~8 and 3(2). Such reproducing operation is performed by first storing respective read data in the field memory 9, and cal-culating -the logical sum of respective bits at each bit position by the arithmetic circuit 10.
This operation will be further e~plained in detail with reference to FIG. 1.
A current (tunnel current) flowing in the probe electrode 1 when -the probe electrode 1 scans the recording medium 2 by means o:E the fine-movement mechanism 4 is amplified by the current amplifier 3, is converted into bi-nary signals (reproduced information) by a comparator (not shown), and is stored in the field memory 9 in units of a scanning line.
The arithmetic circuit 10 calcu:Lates for each bit posi-tion the logical sum of sets of information reprod~ced fromrespective scanning lines which are situated at each cor-responding bit position and stored in the field memory 9.
The logical-sum information is output to the control arith-metic circuit 7 as recorded information. The control arith-metic circuit 7 demodulates the recorded information accord-ing to the outpu-t value.
Example 2 An explanation will now be provided with reference to FIGS. 6, 7(1) and 7(2) of a second example for recording and reproducing information using the appara-tus having the 2~7~9~L8 above-described configuration, wherein -the recording and reproducing operations use multivalue data having at least three values 0, l and 2. The configuration of the apparatus which performs recording and reproducing operations is the same as that shown in FIG. 1. FIG. 6(a) is a schema-tic diagram showing reference-position patterns and recorded signal regions on the recording medium 2. In FIG. 6(a), line (1) represents a first recorded line, and line (2) repre-sents a second recorded line, and wherein five recorded bits are formed on each o-f the recorded lines. A bit indicated b~
a broken circle represents a state of 0, a bit indicated by a solid circle represents a state of 1, and a bit indicated by hatching represents a state of 2. In a recording opera-tion, the position of the probe electrode 1 is controlled in the same manner as in the first example. Voltages having the values of 6V and 3V and the shape of a pulsed waveform shown in FIG. 5 are applied when information to be recorded com-prises 0 and 1, respectively. A pulsed ~oltage having the waveform shown in FIG. ~ is applied when information to be recorded comprises 2. Thus, recording operations using three values are performed such that each of the states represent a different conductivi-ty formed on the recording medium during a recording operation.
In a reproducing operation, since the amoul--t of the tunnel current flowing in accordance with multivalue re-2~7~9~
corded information differs, demodulation is performed so as to provide three values, and data shown in FIGS. 7(1) and 7(2) are obtained. Accordingly, by calculating the logical sum of respective bits in the vertical direction of lines An - Fn in -the same manner as in example 1, information repre-sented by Gn shown in FIG. 7 can be reproduced. Recording and reproducing operations can also be performed by the same processing when multivalue data comprising at least four values are dealt with.
As described above, according to the present invention, tolerance of positional accuracy of a probe in a recording or reproducing operation can be increased, whereby informa-tion can be securely reproduced even if positioning ~tracking) by feedback control is not performed.
INFO~MATION REP~ODUCING NETHOD AND
IN~O~M~TION ~EPRODUCING APPARATUS WHICH USES THE METHOD
BACKG~OUND OF THE INVENTION
Field of the Invention This invention relates to the technical field of high-density and large-capacity memory devices which use, for ex-ample, the principle of a scanning tunneling microscope (hereinafter termed an STM).
Description of -the Prior Art Heretofore, semiconductor memories comprising semicon-ductors and magnetic memories comprising magnetic materials have been mainly used as memories. Recently, however, in ac-cordance with the development of laser techniques, inexpen-sive high-density recording media comprising optical memories which use organic thin films made of organic dyes, photopolymers or the like have appeared.
In addition, STM's which can directly observe the electronic ~tructure of surface atoms of a conductor have been developed (G. Binnig et al. Phys. Rev. Lett. 49, 57 (1982)). The STM has the advantages that a real-space image 2~7~4~
of a material, irrespective of crystal:Line or amorphous, can be measured with high resolution, a sample can be observed at low power without damaging it by current, and since the apparatus operates even in air, it can therefore be used for ~arious ma-terials. Accordingly, a wide range of applica-tions is expected. The STM utilizes the phenomenon that a tunnel current flows when a metal probe (probe electrode) and a conductive substance are brought as close as about 1 nm (nanometer) while applying a voltage between them. The tunnel current is very sensitive to a change in the distance between the probe and the substanceO By scanning tbe probe so as to maintain the tunnel current at a constant value, it is even possible to read various kinds O:e information with respect to the entire electronic cloud of a real space. At that time, resolution in the direction of the plane of the substance is about 0.1 nm.
Accordingly, by applying the principle of the STM, it is possible to sufficiently record and reproduce high-density data in the atomic order (in the order of sub-nanometers). For example, in a recording/reproducing ap-paratus disclosed in Japanese Patent Application Public Dis-closure (Kokai) No. 61-80536 (1986), a writing operation is per~ormed while removing atomic particles adsorbed on the surface of a medium using an elec-tronic beam or -the like, and the writ-ten data is reproduced using an S'l'M.
~7~9gL8 Methods exist in which an STM performs recording and reproducing opera-tions using a thin-film recording layer of a material having a memory effect with respect to voltage-current switching characteris-tics. Examples of recording layer materials include a ~-electron-type organic compound, a chalcogenide compound or the like, and are disclosed, for example, in Japanese Patent Application Public Disclosures (Kokai) Nos. 63-161552 (1988) and 63-161553 (1988). Accord-ing to such methods, large-capacity recording and reproduc-ing operations on the order of 101~ bits/cm~ become possibleassuming the size of recording bits of 10 nms.
In using such recording/reproducing methods, in order to reproduce data with an excellerlt S/N ratio, it is in general necessary to perform so~called tracking ~ontrol wherein a probe electrode is moved along a recorded si~nal string while performing feedback control, since recording bits are very small. For example, a method has been proposed in Japanese Patent Application Public Disclosure (Kokai) No.
1-107341 l1989) wherein a V-shaped groove is previously formed on the sur~ace o~ a recording medium, and a probe electrode is controlled so as to be always situa$ed in the center of the groove. On the other hand, methods which do not require a -tracking operation have been proposed. For ex-ample, a method is disclosed in Japanese Patent Application 25 Public Disclosure (Kokai) No. 2-50333 (1990), wherein, in a 207~9~
reproducing opera-tion~ information is read by scanning a re-corded signal string with a probe electrode with a density higher than the recording density without performing a tracking operation, and recorded information is reproduced using a pattern recognition technique.
However, control is complicated in the above-described methods which use a tracki.ng operation, and a complicated pattern recognition process requiring a long processing time is necessary in -the above-described method which uses pat-tern recognition without using a tracking operation.
SUMMARY OF THE INVENTION
It is an object of the presen-t invention to provide a method and apparatus which can easily reproduce information without performin~ a tracking operation.
In a method of reproducing information by scanning a recorded signal s-tring with a probe with a density higher than the recording density in a reproducing operation, by using a logical-sum signal of a plurality of scanning infor-mation strings as a reproducing signal, it is possible to prevent deteriora-tion in the S/N ratio and the like produced by a posi-tional error of a recording-medium control mechanism caused by various fac-tors in information process-ing.
2~7~8 BRIEF DESCRIPTION OF THE DRAWINGS
FI~. 1 is a diagram showing a recording/reproducing ap-paratus according to an embodiment oi' the present invention;
5FIGS. 2(a) and 2(b) are diagrams illustrating the scan-ning method of a reading system for scanning recorded signals;
FIGS. 3(1~ and 3(2) are diagrams illustrating reproduced information obtained by the scanning method shown in FIG. 2;
FIG. 4 is a diagram showing -the waveform of a write pulse voltage;
FIG. 5 is a diagram showing th,~ waveform of an erase pulse voltage;
15FIGS. 6(a) and 6(b) are diagrams illustrating the scan-nin~ method of a reading syst~m ~or record~d signals in a second embodiment o~ the present invention; and FIGS. 7(1) and 7(2) are di.agrams illustrating reproduced information obtained by the scanning method shown in FIG. 6.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 is a block diagram showing the entire configura-tion o~ an information recording/reproducing apparatus ac-~07~9~
cording to an embodiment of the present invention. In FIG.1, a tungsten needle is used as a probe electrode 1. In or-der to increase resolution in recording and reproducing operations, the front end of the tungsten needle is sharply processed by mechanical polishing, electropolishing or the like. Pt-Ir, Pt or the like may also be used as the material for the probe electrode 1, and the processing method is not limited to the above-described methods. A recording medium 2 comprises a material having the property of switching be-tween states which have different conductivities, that is,a memory switching property in the current-voltage charac-teristic. In -the present embodiment, the recording medium 2 is provided by accumulating eight layers of' SOAZ
(squalirium-bis-6-octyl azulene) on a graphite substrate using the LB (Langmuir-Blodge$t) method. A current amplifier 3 converts a current (tunnel current) flowing in the probe electrode 1 into a voltage and amplif'ies the converted volt-age. A fine-movement mechanism 4 includes cylindrical piezoelectric elements, and finely moves the probe electrode l in the direction of the plane of the recording medium 2 (X
and Y directions) and in the direction to control the amount of space between the recording medium 2 ~nd the probe electrode 1 (Z direction3. A coar~e-movement mechanism 5 in-clude~ parallel springs comprising elastic hinges, and holds and coarsely moves the recording medium 2 in the X and Y
2~709~8 directions. An XYZ controller 6 controls the fine-movement mechanism 4 and -the coarse-movement mechanism 5 by providing them wi-th control voltages. A control arithmetic circuit 7 modulates and demodulates data while controlling the respec-tive units. A voltage applica$ion circuit 8 can app:ly an ar-bitrary voltage between - 10 V (volts) and + 10 V between the probe electrode 1 and the recording medium 2. The volt-age application circuit 8 applies a pulse-like voltage having a value corresponding to the recorded value in recording and erasing operations, and applies a constan-t bias voltage in a reproducing operation. A field memory 9 temporarily stores data read in a reproducing operation. An arithmetic circuit 10 performs logical calculation of infor-mation stored in the ~ield memory 9.
ExamPle 1 As an example of recording and reproducing information using the apparatus having the above-described configura-tion, an explanation will be provided o~ a case wherein recording and reproducing operations are performed ~sing bi-nary values, i~e., 0 (OFF) and 1 (ON). FIG 2 is a schema-tic diagram showing reference-position patterns and recorded signal regions on the recording medium 2. In FIG. 2, line (1) represents a ~irst recorded line, and line (2) repre-sents a second recorded line. Five recording bits are formed on each of the recorded lines. As depicted in FIG. 2(b), a 2~70~
bit indicated oy a broken circle represents a O (OFF) state, and a bit indicated by a solid circle represents a 1 (ON) state.
When recording information using an apparatus having the configuration shown in FIG. 1, care must be taken so as not to produce crosstalk between lines influenced by ac-curacy in the piezoelectric elemen-ts o~ the fine-movement mechanism 4 for driving the probe electrode 1. Accordingly, a recording operation is performed while scanning the probe electrode 1 along the lines (1) and (2) so that the interval D between the lines ~1) and (2~ satisfies the condition of D
> 2 x L/tan ~, where ~ represents the maximum angular error estimated to occur during a reproducing operation, and I.
represents the length o~ one line.
In a recordin8 operation, the space between the record-ing medium 2 and the probe electrode 1 is subjected to feed-back control so that the current between the recording medium 2 and the probe electrode 1 is about 1 pA
(picoampere). The recording medium 2 is scanned with the probe electrode 1 in a predetermined scanning direction using the fine-movement mechanism 4 while maintaining the above-described space between the recording medium 2 and the probe electrode 1. The probe electrode 1 is stopped at the position of prede-ter~lined X and Y coordinates where informa-tion "1" is to be recorded, and the position in the Z direc-2~7~9~8 g tion is fixed. When the distance between the recordingmedium 2 and the probe electrode 1 has been fixed~ a record-ing operation is perEormed by applying a voltage ~write pulse voltage) having the shape of a triangular-wave pulse shown in FIG. 4. When information to be recorded is 0, an erasing operation (0 recording) is performed by applying a voltage (erase pulse voltage) having the shape of a triangular-wave pulse shown in FIG. 5. Such operations are performed for respective recording positions, and the recording operation is terminated.
Next, an explanation will be provided of operations performed when the information on the recording medium 2 which was recorded in the above-described manner is to be reproduced. Data is recorded in respective recorded segments on the recording medium 2 as differences in conductivity.
Hence, determination of OFF or ON i~ performed according to a difference in conductivity. More specifically, in FIG. 1, a constant bias voltage is applied between the probe electrode 1 and the recording medium 2 while scanning the recording medium 2 with the probe electrode 1 by means of the fine-movement mechanism 4, and data is read according -to the value of a tunnel current flowing in accordance with the conductivity of each segment.
In the present invention, in order -to reproduce only inEormation recorded on each line using a scanning density 2~7~8 -- 10 -- , higher -than the recording density in a writing operation, scannin~ is performed so as to cover a region where informa-tion for one line has been recorded, with a scanning inter-val smaller than the size of the recorded bits, i.e., half the size in the present embodiment, as shown in FIG. 2. Six scanning operations, as indica-ted by An, Bn, Cn, Dn, En and Fn (n - 1, 2, ) shown in FIG. 2j are performed for read-ing the recorded information on each line. FIG. 2 shows a state wherein the direction o-f reproducing scanning is in-clined by an angle 0 relative to the recorded lines (1) and(2).
Respective bits on the respective lines An, Bn, Cn, Dn, En and Fn shown in FIGS. 3(1) and 3(2) represent the states of data read in the six respective scanning operations. Al-though the contents of the data may differ in accordancewith the above-described angle ~ of inclination, if a bit comprises 1 (ON), a recorded 1 (ON) must be contained in at least one of the columns representing respective bits in the vertical direction in the data corresponding to the bit on the lines An - Fn shown in FIG. 3(1) and 3(2). If a]l of the bits in the vertical direction are 0 (OFF), the correspond-ing bit comprises 0 (OFF). Accordingly, by calculating the logical sum of respective bits in the vertical direction at each bit position on the lines An Fn, recorded information can be reproduced as represented by Gn shown in FIGS. 3(1) 2~7~8 and 3(2). Such reproducing operation is performed by first storing respective read data in the field memory 9, and cal-culating -the logical sum of respective bits at each bit position by the arithmetic circuit 10.
This operation will be further e~plained in detail with reference to FIG. 1.
A current (tunnel current) flowing in the probe electrode 1 when -the probe electrode 1 scans the recording medium 2 by means o:E the fine-movement mechanism 4 is amplified by the current amplifier 3, is converted into bi-nary signals (reproduced information) by a comparator (not shown), and is stored in the field memory 9 in units of a scanning line.
The arithmetic circuit 10 calcu:Lates for each bit posi-tion the logical sum of sets of information reprod~ced fromrespective scanning lines which are situated at each cor-responding bit position and stored in the field memory 9.
The logical-sum information is output to the control arith-metic circuit 7 as recorded information. The control arith-metic circuit 7 demodulates the recorded information accord-ing to the outpu-t value.
Example 2 An explanation will now be provided with reference to FIGS. 6, 7(1) and 7(2) of a second example for recording and reproducing information using the appara-tus having the 2~7~9~L8 above-described configuration, wherein -the recording and reproducing operations use multivalue data having at least three values 0, l and 2. The configuration of the apparatus which performs recording and reproducing operations is the same as that shown in FIG. 1. FIG. 6(a) is a schema-tic diagram showing reference-position patterns and recorded signal regions on the recording medium 2. In FIG. 6(a), line (1) represents a first recorded line, and line (2) repre-sents a second recorded line, and wherein five recorded bits are formed on each o-f the recorded lines. A bit indicated b~
a broken circle represents a state of 0, a bit indicated by a solid circle represents a state of 1, and a bit indicated by hatching represents a state of 2. In a recording opera-tion, the position of the probe electrode 1 is controlled in the same manner as in the first example. Voltages having the values of 6V and 3V and the shape of a pulsed waveform shown in FIG. 5 are applied when information to be recorded com-prises 0 and 1, respectively. A pulsed ~oltage having the waveform shown in FIG. ~ is applied when information to be recorded comprises 2. Thus, recording operations using three values are performed such that each of the states represent a different conductivi-ty formed on the recording medium during a recording operation.
In a reproducing operation, since the amoul--t of the tunnel current flowing in accordance with multivalue re-2~7~9~
corded information differs, demodulation is performed so as to provide three values, and data shown in FIGS. 7(1) and 7(2) are obtained. Accordingly, by calculating the logical sum of respective bits in the vertical direction of lines An - Fn in -the same manner as in example 1, information repre-sented by Gn shown in FIG. 7 can be reproduced. Recording and reproducing operations can also be performed by the same processing when multivalue data comprising at least four values are dealt with.
As described above, according to the present invention, tolerance of positional accuracy of a probe in a recording or reproducing operation can be increased, whereby informa-tion can be securely reproduced even if positioning ~tracking) by feedback control is not performed.
Claims (4)
1. An information reproducing method for reading information recorded on a recording medium by effecting relative scanning of the recording medium and a probe electrode, said method comprising the steps of:
detecting reproduced information from a predetermined region on the recording medium by scanning the predetermined region a plurality of times at different positions such that a density of scanning lines is higher than a density of information recorded on the predetermined region;
and determining the recorded information by calculating a logical sum of information reproduced during each scanning of the predetermined region.
detecting reproduced information from a predetermined region on the recording medium by scanning the predetermined region a plurality of times at different positions such that a density of scanning lines is higher than a density of information recorded on the predetermined region;
and determining the recorded information by calculating a logical sum of information reproduced during each scanning of the predetermined region.
2. An information reproducing method according to Claim 1, wherein the reproduced information is detected by detecting a current flowing in the probe electrode when a voltage is applied between the recording medium and the probe electrode.
3. An information reproducing method according to Claim 2, wherein the detected current is a tunnel current.
4. An information reproducing apparatus for reading information recorded in a predetermined region on a recording medium by effecting relative scanning of the recording medium and a probe electrode, said apparatus comprising:
a probe electrode;
a stage for holding the recording medium disposed so as to face said probe electrode with a predetermined space between the recording medium and said probe electrode;
driving means for driving said probe electrode so as to scan a recorded region on the recording medium a plurality of times at different positions such that a density of scanning lines is higher than a density of the recorded information;
voltage application means for applying a voltage between said probe electrode and the recording medium;
means for storing values corresponding to current values flowing in said probe electrode during the scanning of the recorded region; and calculation means for determining the reproduced information read from the recording medium by calculating a logical sum of the values corresponding to the plurality of current values stored in said storing means.
a probe electrode;
a stage for holding the recording medium disposed so as to face said probe electrode with a predetermined space between the recording medium and said probe electrode;
driving means for driving said probe electrode so as to scan a recorded region on the recording medium a plurality of times at different positions such that a density of scanning lines is higher than a density of the recorded information;
voltage application means for applying a voltage between said probe electrode and the recording medium;
means for storing values corresponding to current values flowing in said probe electrode during the scanning of the recorded region; and calculation means for determining the reproduced information read from the recording medium by calculating a logical sum of the values corresponding to the plurality of current values stored in said storing means.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3139093A JP3029143B2 (en) | 1991-06-11 | 1991-06-11 | Information playback method |
| JP139093/1991 | 1991-06-11 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2070948A1 CA2070948A1 (en) | 1992-12-12 |
| CA2070948C true CA2070948C (en) | 1998-02-03 |
Family
ID=15237332
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002070948A Expired - Fee Related CA2070948C (en) | 1991-06-11 | 1992-06-10 | Information reproduction by high density scanning |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US5282191A (en) |
| EP (1) | EP0518240B1 (en) |
| JP (1) | JP3029143B2 (en) |
| AT (1) | ATE172318T1 (en) |
| CA (1) | CA2070948C (en) |
| DE (1) | DE69227282T2 (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2080251C (en) * | 1991-10-15 | 1997-12-02 | Shunichi Shido | Information processing apparatus with tracking mechanism |
| JP3599440B2 (en) * | 1994-12-05 | 2004-12-08 | キヤノン株式会社 | Probe position control mechanism of information processing apparatus, probe position control method, and information processing apparatus |
| JPH09320133A (en) * | 1995-10-16 | 1997-12-12 | Canon Inc | Device and method for recording and reproducing and bit detection method |
| US5757760A (en) * | 1996-01-18 | 1998-05-26 | Canon Kabushiki Kaisha | Information recording and/or reproducing apparatus and method for performing recording and/or reproduction of information by using probe |
| JP3912814B2 (en) * | 1996-02-15 | 2007-05-09 | キヤノン株式会社 | Information processing device |
| JP3679525B2 (en) * | 1996-10-07 | 2005-08-03 | キヤノン株式会社 | Information recording / reproducing apparatus and information recording / reproducing method |
| JP3827105B2 (en) * | 1997-02-12 | 2006-09-27 | 株式会社モリタユージー | Ceiling-mounted automatic fire extinguisher |
| JP3091908B2 (en) * | 1997-04-14 | 2000-09-25 | セイコーインスツルメンツ株式会社 | Scanning probe microscope |
| US6195313B1 (en) | 1997-08-29 | 2001-02-27 | Canon Kabushiki Kaisha | Tracking mechanism and method using probes for information recording/reproducing apparatus |
Family Cites Families (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3158846A (en) * | 1961-01-23 | 1964-11-24 | Silverman Daniel | Information retrieval systems |
| US3322935A (en) * | 1963-07-08 | 1967-05-30 | Honeywell Inc | Optical readout device with compensation for misregistration |
| US4313134A (en) * | 1979-10-12 | 1982-01-26 | Rca Corporation | Track error correction system as for video disc player |
| JPS5823309A (en) * | 1981-07-31 | 1983-02-12 | Victor Co Of Japan Ltd | Descrambling circuit |
| FR2525376B1 (en) * | 1982-04-19 | 1988-02-26 | Lewiner Jacques | IMPROVEMENTS IN DEVICES FOR READING QUANTITIES OF ELECTRIC CHARGES CARRIED BY A DIELECTRIC SHEET |
| FR2526987B1 (en) * | 1982-05-14 | 1987-07-03 | Bull Sa | OPTO-ELECTRONIC METHOD FOR READING INFORMATION CONTAINED ON A MAGNETIC MEDIUM AND CIRCUIT FOR IMPLEMENTING IT |
| JPS59126264A (en) * | 1983-01-07 | 1984-07-20 | Matsushita Electric Ind Co Ltd | Drop-out evaluation apparatus |
| US4878213A (en) * | 1984-09-14 | 1989-10-31 | Xerox Corporation | System for recording and readout of information at atomic scale densities and method therefor |
| JPS6180536A (en) * | 1984-09-14 | 1986-04-24 | ゼロツクス コーポレーシヨン | Apparatus and method for recording and reading atom-size density information |
| US4896025A (en) * | 1986-02-20 | 1990-01-23 | Canon Kabushiki Kaisha | Information reproducing apparatus for information recording medium having a plurality of information tracks |
| JPS63104274A (en) * | 1986-10-21 | 1988-05-09 | Seiko Epson Corp | Track cross signal generating circuit |
| JP2556491B2 (en) * | 1986-12-24 | 1996-11-20 | キヤノン株式会社 | Recording device and recording method |
| JP2556492B2 (en) * | 1986-12-24 | 1996-11-20 | キヤノン株式会社 | Reproduction device and reproduction method |
| US4826732A (en) * | 1987-03-16 | 1989-05-02 | Xerox Corporation | Recording medium |
| JP2851855B2 (en) * | 1988-08-12 | 1999-01-27 | キヤノン株式会社 | Recording and playback device |
| JPH01107341A (en) * | 1987-10-21 | 1989-04-25 | Hitachi Ltd | Recording and reproducing device for electric wire |
| US5222060A (en) * | 1989-09-07 | 1993-06-22 | Canon Kabushiki Kaisha | Accessing method, and information processing method and information processing device utilizing the same |
| JP2783646B2 (en) * | 1990-04-18 | 1998-08-06 | キヤノン株式会社 | Information recording / reproducing device |
| DE69125552T2 (en) * | 1990-09-14 | 1997-10-09 | Canon Kk | Tracking method for storage device |
-
1991
- 1991-06-11 JP JP3139093A patent/JP3029143B2/en not_active Expired - Fee Related
-
1992
- 1992-06-03 US US07/893,043 patent/US5282191A/en not_active Expired - Fee Related
- 1992-06-05 DE DE69227282T patent/DE69227282T2/en not_active Expired - Fee Related
- 1992-06-05 EP EP92109596A patent/EP0518240B1/en not_active Expired - Lifetime
- 1992-06-05 AT AT92109596T patent/ATE172318T1/en not_active IP Right Cessation
- 1992-06-10 CA CA002070948A patent/CA2070948C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| ATE172318T1 (en) | 1998-10-15 |
| EP0518240A3 (en) | 1995-02-22 |
| EP0518240B1 (en) | 1998-10-14 |
| CA2070948A1 (en) | 1992-12-12 |
| US5282191A (en) | 1994-01-25 |
| DE69227282D1 (en) | 1998-11-19 |
| EP0518240A2 (en) | 1992-12-16 |
| JP3029143B2 (en) | 2000-04-04 |
| JPH04364244A (en) | 1992-12-16 |
| DE69227282T2 (en) | 1999-06-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5485451A (en) | Information processing apparatus | |
| CA2047801C (en) | Information recording and/or reproducing apparatus | |
| US6195313B1 (en) | Tracking mechanism and method using probes for information recording/reproducing apparatus | |
| US5453970A (en) | Molecular memory medium and molecular memory disk drive for storing information using a tunnelling probe | |
| JPH06195769A (en) | Information processor with multi-probe | |
| US5251200A (en) | Tracking method for memory apparatus | |
| CA2070948C (en) | Information reproduction by high density scanning | |
| US5432771A (en) | Information recording/reproducing apparatus for performing recording/reproduction of information by using probe | |
| US5287342A (en) | Apparatus and method for reproducing information | |
| EP0603705B1 (en) | Image signal processing apparatus | |
| CA2040703C (en) | Method of access to recording medium, and apparatus and method for processing information | |
| US5757760A (en) | Information recording and/or reproducing apparatus and method for performing recording and/or reproduction of information by using probe | |
| US5255259A (en) | Method of access to recording medium, and apparatus and method for processing information | |
| JP3135753B2 (en) | Recording / reproducing method and apparatus using probe | |
| JP2930449B2 (en) | Tracking method | |
| JP3095915B2 (en) | Information processing device | |
| JP3093946B2 (en) | recoding media | |
| JP3053142B2 (en) | Information processing device | |
| JP3014855B2 (en) | Recorded information playback device | |
| JP2962603B2 (en) | Information recording method | |
| JP3044417B2 (en) | Information processing device | |
| JP2968610B2 (en) | Information recording / reproducing device | |
| JP4079397B2 (en) | Tracking mechanism and tracking method for recording / reproducing apparatus | |
| JPH09198727A (en) | Information recording and reproducing device | |
| JPH02292752A (en) | Recording and reproducing device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |