JPH09306046A - Recording and reproducing method and recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a reproduction at high speed by using a probe for recording and a prove for reproduction whose tip forms are different, thus improving stability at the reproduction. SOLUTION: Information are recorded by applying a physical action with respect to a recording medium 100 while using the probe for recording 104 arranged by being faced to the medium 100 and changing a physical state or the chemical state. The information are produced by an interactive action with the recording medium 100 while using a probe for reproduction 105 different from the probe for recording 104. Then, tip forms of the probe for recording 104 and the probe for reproduction 105 are differentiated. The different tip forms are made by changing curvatures of the proves. Moreover, the tips of the probe for recording 104 and the probe reproduction 105 are formed with thin films made of particulates and the forming of the thin films is performed by changing particle sizes of particulates.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing method and a recording / reproducing method for recording information on a recording medium while two-dimensionally scanning a scanning microscope probe relative to the recording medium and reproducing the recorded information. It relates to the device.

[0002]

2. Description of the Related Art At present, as a method of recording information, a magnetic method such as a magnetic tape or a magnetic disk, an electrical method such as a semiconductor element, etc. are widely used. However, with the increase in size of information, the demand for large capacity of information recording has become very strong. On the other hand, in recent years, a scanning tunneling microscope (hereinafter referred to as STM) [G. Bin
nig et al. , Physical Review
Letters, Vol. 49, p. 57 (1982)] has been developed to enable real space observation at the atomic and molecular level.

The scanning tunneling microscope scans while controlling the distance between the probe electrode and the sample so as to keep the tunnel current constant, and the information of the electron cloud on the sample surface and the sample shape are obtained from the control signal at each time. It can be observed on the order of sub-nanometers. An atomic force microscope (hereinafter referred to as AFM) has been developed as a means for observing the surface of a substance with high resolution. A means for observing physical information of the sample surface from the interaction between the probe and the sample surface, such as STM or AFM, which performs two-dimensional scanning of the sample surface, is generally a scanning probe microscope (hereinafter, SP
It is called M), and is attracting attention as a high-resolution surface observation method.

Therefore, if these principles of SPM are applied,
It is possible to perform recording / reproducing at a high density sufficiently on the atomic order (sub-nanometer order). For example, U.S. Pat. No. 4,575,822 discloses a method of recording at high density using STM. In addition, JP-A-63-161552 and JP-A-63-1615.
JP-A-53-53 discloses a technique for recording by applying a voltage to the insulating film by using the STM technique to cause a change in the conductivity of the insulating film.

[0005]

However, when recording / reproducing is performed by using the SPM technique as described above, the time required for reproduction becomes long because the intensity of the reproduced signal is not sufficient. There is a possibility that the S / N is weak and erroneous reproduction is performed. Further, the time required for tracking becomes long, and the time required for reproduction may also become long. Therefore, in order to solve the above problems, the present invention provides a recording / reproducing method and a recording / reproducing apparatus capable of improving stability at the time of reproduction and performing high-speed reproduction in recording / reproduction using the SPM technique. It is an object.

[0006]

In order to solve the above problems, the present invention has a recording / reproducing method and a recording / reproducing apparatus configured as follows. That is, in the recording / reproducing method of the present invention, a physical action or a chemical state of the recording medium is applied by applying a physical action to the recording medium by using the recording medium and the recording probe arranged to face the recording medium. Information is recorded by changing the target state, and a reproducing probe different from the recording probe arranged facing the recording medium is used to cause the recording medium to interact with the recording medium. A recording / reproducing method for reproducing recorded information,
The recording / reproducing is performed by a recording probe and a reproducing probe having different tip shapes.
Further, the recording / reproducing apparatus of the present invention comprises a recording medium, a recording probe arranged to face the recording medium, and a recording probe arranged to face the recording medium. A probe, a physical action applying means for applying a physical action to the recording medium by the recording probe, and an interaction detecting means for detecting an interaction acting between the recording medium and the reproducing probe. And a probe position moving means for moving the relative position of the probe and the recording medium, wherein the recording probe and the reproducing probe have different tips. It is characterized by having a shape. In the present invention, the different tip shape can be achieved by changing the curvature of the tip of the probe.
This can be performed by forming the tips of the recording probe and the reproducing probe with a thin film of fine particles and changing the particle size of the fine particles. At that time, it is more preferable that the curvature of the tip of the reproducing probe is larger than that of the tip of the recording probe.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The recording / reproducing method of the present invention has the above-mentioned structure, in which the recording medium has an electrical state, a magnetic state, an optical state, a chemical structure, a surface structure and the like. The recording probe is configured by a medium in which information is recorded by being changed, and the recording probe performs a physical action in a state of approaching or in contact with the recording medium to record the information in the recording medium. The physical action mentioned here includes voltage, current, magnetism, light, force and the like. The reproducing probe interacts with the recording medium in a state of approaching or in contact with the recording medium, and reproduces the recorded information recorded on the recording medium based on the interaction. Here, the interaction generated between the recording medium and the reproducing probe is an atomic force, an intermolecular force, an electric current, an electromagnetic force, a magnetic force, or the like. In the present invention, the tip of the recording probe refers to a portion of the recording probe that is effective when a physical action is applied to the recording medium. Further, the tip of the reproducing probe means a portion where an interaction that acts between the reproducing probe and the recording medium occurs during reproduction. In the present invention, the tip of the recording probe and the tip of the reproducing probe are different from each other, and have, for example, a shape suitable for generating an interaction for reproduction. Examples of the shape here include the radius of curvature of the tip. In the recording / reproducing method according to the present invention, a physical action of the recording medium is applied to the recording medium to change the physical state of the recording medium. Information is recorded by setting a recording bit at a place where the change in the physical state occurs. Next, the interaction between the recording medium and the recording medium is detected by the reproducing probe.
Since the magnitude of the interaction is different at the place where the recording bit is formed, the recorded recording bit is detected and the information is reproduced. In the present invention, the shape of the reproducing probe is optimized for reproduction, so that reproduction can be speeded up and stability can be improved. By increasing the radius of curvature of the tip of the reproducing probe to be larger than the radius of curvature of the tip of the recording probe, the volume and area of the reproducing probe that interacts with the recording medium at the time of reproduction are increased. As S / N during playback
It is possible to improve the stability at the time of reproduction and to improve the reproduction speed. Further, since the allowable range of the position where the interaction with the recording bit existing on the recording medium can be generated at the time of reproduction is widened and as a result, tracking is easily performed, the reproduction speed can be increased.

The recording / reproducing apparatus of the present invention has the above-mentioned structure, and the recording medium, the recording probe, and the reproducing probe therein are as described in the recording / reproducing method. The physical action applying means of the apparatus of the present invention generates a physical action applied to the recording medium by the recording probe, and is a power source, a magnet, a light source, or the like. The interaction detecting means detects an interaction occurring between the reproducing probe and the recording medium, and is, for example, a current amplifier, a photodetector such as a photodiode, or the like. Further, when the reproducing probe is supported by the elastic body, the means for detecting the deformation of the elastic body serves as means for detecting the interaction acting with the recording medium. Further, in this case, it is possible to detect magnetism by using a magnetic material for the reproducing probe. The probe position moving means moves the tip of the probe to a desired position at the time of recording or reproducing, and may be, for example, a piezo element or a stepping motor. When applying a force from the probe to the recording medium, the probe position moving means can also serve as the physical action applying means. That is, the probe can be applied to the recording medium by bringing the probe closer to the recording medium by pressing the probe with the probe position moving means.
Also in the recording / reproducing apparatus of the present invention, similarly to the recording / reproducing method, the tips of the recording probe and the reproducing probe are different from each other, and for example, they have a shape suitable for generating interaction for reproduction. . Examples of the shape here include the radius of curvature of the tip.

In the recording / reproducing method according to the present invention, the physical action generated by the physical action applying means is applied to the recording medium by the recording probe to change the physical state of the recording medium. Information is recorded by setting a recording bit at a place where the change in the physical state occurs. Next, the interaction detection means detects the interaction with the recording medium by the reproducing probe. Since the magnitude of the interaction is different at the place where the recording bit is formed, the recorded recording bit is detected and the information is reproduced. In the present invention, the shape of the reproducing probe is optimized for reproduction, so that reproduction can be speeded up and stability can be improved. By making the radius of curvature of the tip of the reproducing probe larger than the radius of curvature of the tip of the recording probe, the volume and area of the reproducing probe side that interacts with the recording medium at the time of reproducing becomes large, and the result As a result, the S / N ratio at the time of reproduction is improved, the stability at the time of reproduction can be improved, and the reproduction speed can be improved. In addition, since the allowable range of the position that can interact with the recording bit existing on the recording medium at the time of reproduction is widened, as a result, tracking can be easily applied,
The playback speed can be increased.

[0010]

Embodiments of the present invention will be described below.
FIG. 1 shows a recording / reproducing apparatus used when executing the present invention. The recording / reproducing apparatus includes a recording medium 100 and a recording probe 1.
04, reproducing probe 105, cantilever 106, cantilever 107, power supply 108, reproducing current amplifier 109,
XY direction position control circuit 110, Z direction position control circuit 1
11, a recording medium stage drive mechanism 112, a recording medium stage 113, and a microcomputer 114.

Further, the recording medium 100 is made of polyimide (P
I) LB film 101, Au thin film 102, mica substrate 10
It is composed of 3 and is recorded by a polyimide LB film 10
Recording is performed using a change in conductivity of 1. Au thin film 102
Is vapor-deposited on mica 103 at a high temperature, and is epitaxially grown on mica 103.

In this embodiment, a recording probe 104 and a reproducing probe 105 are provided, each of which is a cantilever 1.
06, supported by the cantilever 107. In this embodiment, the cantilevers 106 and 107 are used in a normal atomic force microscope, and the spring constant k = 0.1N.
/ M was used. The recording probe 104 used in this embodiment is shown in FIG. The reproducing probe 105 used in this embodiment is shown in FIG.

The recording probe 104 and the reproducing probe 105 are both made of Si, and a Pt thin film 201 and a Pt thin film 202 are attached to the surface thereof by a sputtering method. The grain diameter of the Pt thin film 201 is about 20 nm,
The grain size of 2 was about 50 nm. These Pt thin films 201,
202 is connected to the power supply 108.

The power supply 108 is the microcomputer 11
According to the instruction No. 4, a pulse voltage for recording is applied to the Pt thin film 201 of the recording probe 118 during recording. At the time of reproduction, the bias voltage necessary for reproduction is applied to the Pt thin film 202 of the reproduction probe 119. The reproducing current amplifier 109 passes the reproducing probe 105 through the recording medium 1 during reproduction.
The current flowing through the polyimide LB film 101 of 00 is detected,
The value is sent to the microcomputer 114. The microcomputer 114 reproduces the information based on the value.

The recording medium stage 113 is a recording medium 100.
And a recording medium stage drive mechanism 11
Reference numeral 2 moves the recording medium stage 113 in the X-Y directions in the drawing to move the recording probe 104, the reproducing probe 105 and the positions of the recording medium 100 in the X and Y directions. XY
The direction position control circuit 110 is a microcomputer 114.
The command regarding the position of the recording medium stage drive mechanism 112 in the X-Y directions is performed by the command from the.

The recording probe distance control mechanism 115 comprises a stepping motor and a piezo element, and can move the recording probe 104 in the z direction in the figure. Also,
The reproducing probe distance control mechanism 116 is composed of a stepping motor and a piezo element, and can move the reproducing probe 105 in the z direction in the drawing.

When recording, the microcomputer 114 first sends to the probe control circuit 117 a signal indicating that the recording operation is to be performed. The probe control circuit 117 commands the recording probe distance control mechanism 115 to bring the recording probe 104 into contact with the recording medium 100, and instructs the reproducing probe distance control mechanism 116 to separate the reproducing probe 119 from the recording medium 100. To do.

According to this command, the recording probe distance control mechanism 115 brings the recording probe 118 close to the recording medium 100 and brings the recording probe 104 into contact with the recording medium 100. Further, the reproducing probe distance control mechanism 116 separates the reproducing probe 119 from the recording medium 100.

Next, the microcomputer 114 makes the XY
A signal relating to the position in the XY direction is sent to the directional position control circuit 110, and the recording medium stage drive mechanism 112 moves in the XY direction by the control signal from the XY direction position control circuit 110, and the recording probe 104. The tip is moved to a position in the XY direction where recording is desired on the surface of the recording medium 100. Then, in response to a command from the microcomputer 114, X-Y
The directional position control circuit 110 includes the recording medium stage drive mechanism 1
12 is raster-scanned at 50 Hz. Then, in response to a command from the microcomputer 114, the power supply 108 generates a recording pulse voltage, and through the recording probe 104,
It is applied to the PILB film 101. By the above operation, the conductivity of the portion of the PILB film 101 to which the voltage is applied rises, and this becomes a recording bit.

In this embodiment, the conductivity is increased by applying a recording voltage to the location corresponding to the information "1". Further, the voltage for recording is not applied at a position corresponding to "0", and the conductivity is not changed. When performing reproduction, first, the microcomputer 114 sends a signal to the probe control circuit 117 indicating that the reproduction operation is to be performed. The probe control circuit 117 commands the recording probe distance control mechanism 115 to separate the recording probe 104 from the recording medium 100, and instructs the reproducing probe distance control mechanism 116 to bring the reproducing probe 119 into contact with the recording medium 100. To do.

In accordance with this command, the recording probe distance control mechanism 115 separates the recording probe 118 from the recording medium 100, and the reproducing probe distance control mechanism 116 causes the reproducing probe 119 to approach the recording medium 100 for reproducing. The probe 105 is brought into contact with the surface of the recording medium 100. Next, the microcomputer 114 sends a signal regarding the position in the XY direction to the XY position control circuit 110, and the XY position is controlled.
The recording medium stage drive mechanism 112 moves in the XY direction in response to a control signal from the directional position control circuit 110, and moves the tip of the reproducing probe 105 to an approximate position in the XY direction where the surface of the recording medium 100 is desired to be reproduced. To do. Next, the power supply 108 generates a bias voltage for reproduction according to a command from the microcomputer 114, and a voltage is applied between the reproduction probe 105 and the Au thin film 102. At this time PIL
The current flowing through the B film 101 is detected by the reproducing current amplifier 109, and the value is sent to the microcomputer 114. A large amount of current flows in the place corresponding to the information of "1" because the conductivity increases, and a small amount of current flows in the place corresponding to "0" because the conductivity does not change.
As a result, the microcomputer 114 has the information "1".
And play "0". In this embodiment, the XY direction position control circuit 11 is instructed by a command from the microcomputer 114.
0 commands the recording medium stage drive mechanism 112 to reproduce the recording bits one after another while tracking the recording bits.

In this embodiment, the radius of curvature of the reproducing probe 105 is larger than the radius of curvature of the tip of the recording probe 104. Therefore, the area in contact with the recording medium at the time of reproduction becomes large, and the current flowing during reproduction can be increased. Therefore, the playback time required for each bit can be reduced and the playback speed can be increased.
Further, the S / N was improved by increasing the reproduction current value, and the read error rate could be suppressed. Further, since the area in contact with the recording medium also becomes large, the allowable range of the position in the XY direction of the tip of the reproducing probe for detecting the recording bit is widened. FIGS. 4 and 5 show how recorded bits are detected when the radius of curvature of the tip of the reproducing probe is small (when the particles are small) and when the radius of curvature is large (when the particles are large). In this way, the permissible range of the position in the XY direction of the tip of the reproducing probe for detecting the recording bit is widened, which facilitates tracking of the recording bit, reduces the time required for tracking, and reduces the reproduction speed. Can be fast.

[0023]

As described above, according to the present invention, the shape of the reproducing probe can be optimized for reproduction, and the reproduction speed can be increased and the stability at the time of reproduction can be improved. . In particular, by making the radius of curvature of the tip of the reproducing probe larger than the radius of curvature of the tip of the recording probe, the volume and area on the side of the reproducing probe that interacts with the recording medium at the time of reproducing becomes large. It is possible to improve the S / N ratio during reproduction, improve stability during reproduction, and improve the reproduction speed. In addition, the permissible range of the position where the interaction with the recording bit existing in the recording medium can be generated at the time of reproduction, and thus the tracking can be easily performed and the reproduction speed can be increased.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a recording / reproducing apparatus used in an example.

FIG. 2 is a diagram showing a recording probe used in Examples.

FIG. 3 is a diagram showing a reproducing probe used in Examples.

FIG. 4 is a diagram showing recorded bits when the radius of curvature of the tip of the reproducing probe is small (when particles are small).

FIG. 5 is a diagram showing recorded bits when the radius of curvature is large (when the particles are large).

[Description of sign]

 100: recording medium 101: polyimide (PI) LB film 102: Au thin film 103: mica substrate 104: recording probe 105: reproducing probe 106: cantilever 107: cantilever 108: power supply 109: reproducing current amplifier 110: X -Y direction position control circuit 112: recording medium stage drive mechanism 113: recording medium stage 114: microcomputer 115: recording probe distance control mechanism 116: reproduction probe distance control mechanism 117: probe control circuit 118: recording probe 119: Reproduction probe 201: Pt thin film

Claims (8)

[Claims] 1. A recording medium and a recording probe arranged to face the recording medium are used to apply a physical action to the recording medium to change a physical state or a chemical state of the recording medium. Information is recorded thereby, and information recorded on the recording medium is recorded by interaction with the recording medium by using a reproducing probe different from the recording probe arranged facing the recording medium. A recording / reproducing method for reproducing, wherein the recording / reproducing is performed by a recording probe and a reproducing probe having different tip shapes. 2. The recording / reproducing method according to claim 1, wherein the different tip shape is caused by a change in curvature. 3. The change of the curvature is characterized in that the tips of the recording probe and the reproducing probe are formed of a thin film of fine particles and the particle diameter of the fine particles is changed. Recording and playback method. 4. The recording / reproducing method according to claim 2, wherein the curvature of the tip of the reproducing probe is larger than that of the tip of the recording probe. 5. A recording medium, a recording probe arranged to face the recording medium, a reproducing probe different from the recording probe arranged to face the recording medium, and A physical action applying means for applying a physical action to the recording medium by the recording probe; an interaction detecting means for detecting an interaction acting between the recording medium and the reproducing probe; and the probe. And a probe position moving means for moving a relative position between the recording medium and the recording medium, wherein the recording probe and the reproducing probe have different tip shapes. A recording / reproducing device characterized in that 6. The recording / reproducing apparatus according to claim 5, wherein the different tip shapes have different shapes due to changes in curvature. 7. The change in curvature is characterized in that the tips of the recording probe and the reproducing probe are formed of a thin film of fine particles, and the particle diameter of the fine particles is changed. Recording and reproducing device. 8. The recording / reproducing apparatus according to claim 6, wherein the curvature of the tip of the reproducing probe is larger than that of the tip of the recording probe.