Information recording/reproducing apparatus

A probe group is composed of, for instance, four probes adjacently arranged, and one modulation circuit is arranged for each probe group. At the time of recoding information, a changeover switch connects one of the four probes with the modulation circuit, and subsequently changes the probes to be connected with the modulation circuit while reciprocal movement of a recording medium is being controlled.

This application is the U.S. national phase of International Application No. PCT/JP2007/058445, filed 18 Apr. 2007, which designated the U.S. and claims priority to JP Application No. 2006-114221, filed 18 Apr. 2006, the entire contents of each of which are hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to an information recording/reproducing apparatus for recording or reproducing information with respect to an information recording medium, using a plurality of probes, such as a scanning probe memory apparatus, for example.

BACKGROUND ART

As a small-sized information memory apparatus which can record information highly densely, a scanning probe memory apparatus is listed.

The scanning probe memory apparatus has various types: using a tunnel effect, using an atomic force, using a magnetic force, using an electrostatic force, using a non-linear dielectric constant, and using heat deformation of a recording medium.

The scanning probe memory apparatus is normally provided with: a probe having a tip with a radius of about several tens nanometers to several micrometers; and a plate-like (or flat) recording medium having a recording surface formed on its surface. The scanning probe memory apparatus brings the tip of the probe closer to or into contact with the recording surface of the recording medium, to thereby perform information recording or reading on the recording medium.

Moreover, the scanning probe memory apparatus displaces the probe or the recording medium in a parallel direction to the recording surface, to thereby change the positional relation between the probe and the recording medium. By this, it is possible to scan the recording surface of the recording medium, using the probe, so that a large amount of information can be arranged on the recording surface, highly densely. Alternatively, the large amount of information arranged on the recording surface can be read, continuously or randomly. For such displacement of the probe or the recording medium, an electromagnetically-driven or electrostatically-driven actuator using e.g. a MEMS (Micro Electro Mechanical System) technology is used.

Moreover, most scanning probe memory apparatuses adopt a multi-probe method. That is, most scanning probe memory apparatuses are provided with: a two-dimensional probe head in which several tens, or several hundreds, or several thousands of probes are arranged in a matrix, for example. By using such a probe head, it is possible to quickly record the large amount of information into the recording medium, or it is possible to quickly read the large amount of information from the recording medium.

DISCLOSURE OF INVENTION

Subject to be Solved by the Invention

By the way, in order to improve the performance of the probe memory apparatus, it is required to increase an information recording speed and an information reading speed, to limit or control power consumption by the driving of an actuator, and to reduce the size of the probe memory apparatus, and the like.

As one method responding to these requirements in a balanced manner, there is a method of reducing the stroke amount of the actuator for displacing the probe or the recording medium in the parallel direction to the recording medium.

For example, by reducing the stroke amount of the actuator, it is possible to increase the driving frequency of the actuator. By this, it is possible to displace the probe or the recording medium at high speed in the parallel direction to the recording medium.

Moreover, by reducing the stroke amount of the actuator, the minimum resonance frequency of the actuator is set to be high. Then, the actuator is driven at a frequency near the minimum resonance frequency. By this, it is possible to reduce the power consumption by the driving of the actuator.

Moreover, by reducing the stroke amount of the actuator, it is possible to reduce the travel distance of the probe head or the recording medium which is displaced in the parallel direction to the recording surface. By this, it is possible to reduce the length or width of the probe memory apparatus in the parallel direction to the recording surface.

However, the reduction in the stroke amount of the actuator causes the following problems.

That is, if the stroke amount of the actuator is reduced on the premise that there is no change in an information recording capacity, in an information recording density, and in an area size of a recording area of the recording medium, then the number of probes is increased and an interval of probes is reduced.

For example, it is assumed that in the probe memory apparatus before the design change, the recording area of the recording medium is a square 2 mm on a side, the stroke amount of the actuator is 200 μm, the number of the probes is 10×10 (=100), and the interval of the adjacent probes is 200 μm.

Then, it is assumed that the design of the probe memory apparatus is changed and the stroke amount of the actuator is changed to 100 μm. Then, the number of the probes is 20×10 (=200), and the interval of the adjacent probe is 100 μm.

On the premise that the information recorded on the recording medium is read simultaneously through each probe, it is necessary to provide each probe with a demodulation circuit for demodulating a reading signal, or the like. Moreover, it is desired to dispose the demodulation circuit near each probe in view of shortening of a wiring pattern or a reduction in noise. As a result, if the number of probes is 200, 200 demodulation circuits are desirably disposed on the probe head.

The reduction in the interval of the adjacent probes causes such a problem that it is hard to ensure a space to dispose the demodulation circuits on the probe head.

On the other hand, on the premise that the information recorded on the recording medium is read simultaneously through each probe, it is desired to convert a plurality of reading signals, which are supplied from the plurality of probes in parallel, to one reading signal by parallel-serial conversion and to send the one reading signal to a reproduction circuit or the like disposed in the downstream of the probe head.

However, if the number of the probes is increased, then the number of the reading signals, which are supplied from the plurality of probes in the information reading, is also increased. Thus, there is such a problem that a buffer memory with a large memory capacity is required in order to perform the parallel-serial conversion on the reading signals.

In view or the aforementioned problems, it is therefore an object of the present invention to provide an information recording/reproducing apparatus, which can reduce the stroke amount of the actuator for displacing the probe head or the recording medium in the parallel direction to the recording surface.

It is a second object of the present invention to provide an information recording/reproducing apparatus, which can reduce the number of the reading signals, supplied from the respective probes in parallel in the information reading, as compared with the number of the probes provided for the probe head.

Means for Solving the Subject

The above object of the present invention can be achieved by an information recording/reproducing apparatus provided with: a recording medium having a recording surface; a probe head in which one or a plurality of probe groups are arranged, the probe group including a plurality of probes which are close to each other and which record or read information with respect to the recording surface of the recording medium; an actuator which performs displacement control of the recording medium or the probe head in order to reciprocate the recording medium or the probe head in a parallel direction to the recording surface; a signal processing circuit which is provided for each probe group and which supplies the each probe with a recording signal corresponding to the information to be recorded onto the recording surface of the recording medium, or which receives a reading signal corresponding to the information read from the each probe; and a changing device which connects one of a plurality of probes included in the each probe group with the signal processing circuit corresponding to the probe group and which changes a probe to be connected to the signal processing circuit during the displacement control of the recording medium or the probe head.

These effects and other advantages of the present invention will become more apparent from the embodiments explained below.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the best mode for carrying out the invention will be explained in each embodiment in order, with reference to the drawings.

First Embodiment

Firstly, an explanation will be given on the basic function of a scanning probe memory apparatus in a first embodiment of the present invention.

FIG. 1is a cross sectional view showing a scanning probe memory apparatus in a first embodiment of the information recording/reproducing apparatus of the present invention.

A scanning probe memory apparatus1inFIG. 1is a small-sized apparatus, for example, which is several millimeters to several centimeters in length and in width (length in a horizontal direction inFIG. 1) and which is several millimeters in thickness (length in a vertical direction inFIG. 1), in external dimension.

The probe memory apparatus1can record information onto a recording surface13D of a recording medium13, highly densely, using probes17A to17D, and has a huge memory capacity regardless of its small size. For example, the memory capacity is several tens to several hundreds gigabytes, and can also exceed a terabyte.

The probe memory apparatus1records the information using the spontaneous polarization of a ferrorelectric substance. That is, the tips of the probes17A to17D are brought closer to or into contact with the recording surface13D of the recording medium13, which has a recording layer13C formed of a ferrorelectric material, and a voltage exceeding a coercive electric field of the ferroelectric substance is applied through the probes17A to17D. By this, the polarization direction of the ferroelectric substance is changed, to thereby record the information. Moreover, the reproduction of the information recorded in the recording medium13is performed by a SNDM (Scanning Nonlinear Dielectric Microscopy) method.

Moreover, the probe memory apparatus1is provided with an actuator18, and the driving of the actuator18allows the recording medium13to be displaced in a parallel direction to the recording surface13D. On the other hand, the probes17A to17D are mounted on a probe head15, and the probe head15is fixed to a housing12. By this, it is possible to change the relative position between the probes17A to17D and the recording medium13, to thereby scan the recording surface13D by using the probes17A to17D.

Moreover, the probe head15has 20×20 (=400) probes17A to17D arranged. By this, it is possible to quickly record a large amount of information onto the recording surface13D, or to quickly read a large amount of information from the recording surface13D.

Next, the structure of the probe memory apparatus1will be specifically explained.

As shown inFIG. 1, the probe memory apparatus1has a plate-like housing11disposed in the lower portion and the cup-shaped housing12disposed in the upper portion. There is a space formed between the housing11and the housing12.

In the space formed between the housing11and the housing12, the recording medium13is disposed. There is also a vacant space or gap between the lower surface of the recording medium13and the upper surface of the housing11. Moreover, there is also a vacant space or gap between the upper surface of the recording medium13and the lower surface of the housing12. Moreover, each side surface of the recording medium13is away from each inner side surface of the housing12facing the side surface of the recording medium13.

The recording medium13is supported by the housing12using a support member, which is one of the constituent elements of the actuator18.

The recording medium13is provided with: a substrate13A; an electrode13B; and the recording layer13C. The upper surface of the recording layer13C is the recording surface13D. The substrate13A is plate-like, and is formed of SiO2, for example. The electrode13B is formed of copper, for example. The recording layer13C is formed of a ferroelectric material, such as LiTaO3or LiNbO3. Each of the recording layer13C and the electrode13B is desirably a thin layer with a thickness of 1 μm or less. The substrate13A has a thickness of about 500 μm to 1 mm, for example.

The recording medium13has a recording area formed on the recording surface13D, and information is recorded into the recording area. Moreover, the recording area is a square, for example, 2 mm on a side in the external shape. Moreover, the recording area is virtually divided into 20×20 (=400) recording unit areas. Each recording unit area is a square, for example, 100 μm on a side. One probe17A,17B,17C, or17D is assigned to each recording unit area of the recording medium13.

Moreover, the probe head15is disposed in the space formed between the housing11and the housing12. The probe head15is disposed above the recording medium13.

The probe head15is provided with: a probe support substrate16; and 20×20 (=400) probes17A to17D. Each of the probes17A to17D is used to perform the information recording or information reading on the recording surface13D of the recording medium13. The tip diameter of each of the probes17A to17D is about 25 nm, for example.

The 400 probes17A to17D are provided on the flat surface of the probe support substrate16; namely, 20 probes are arranged at substantially even intervals along an X direction, and 20 probes are arranged at substantially even intervals along a Y direction. The X direction is a parallel direction to the recording surface13D, and the Y direction is parallel to the recording surface13D and crosses the X direction at almost right angles.

Moreover, an interval of the tips of the probes adjacent to each other in the X direction is 100 μm, and an interval of the tips of the probes adjacent to each other in the Y direction is also 100 μm.

Moreover, the probe head15is provided with100primary circuit units30(refer toFIG. 2). The details of the primary circuit unit30will be detailed later.

Moreover, the actuator18is disposed in the space formed between the housing11and the housing12. The actuator18performs displacement control on the recording medium13, in order to displace the recording medium13in the X direction and the Y direction.

The actuator18is provided with: a support member and a driving device. The support member supports the recording medium13on the housing12in such a condition that the recording medium13can be displaced in the X direction and the Y direction. The support member is formed by processing a silicon material into a predetermined shape, for example.

The driving device is provided with an electromagnetically-driven type driving mechanism. Incidentally, instead of the electromagnetically-driven type driving mechanism, the driving device may use an electrostatically-driven type driving mechanism or a piezoelectrically-driven driving mechanism.

Moreover, the probe memory apparatus1is provided with a post-circuit unit40. The post-circuit unit40is mounted on the housing12, for example.

Next, a specific explanation will be given on the structures of the probe head15and the post-circuit unit40.

The left side ofFIG. 2shows one portion of the probe head15. This drawing shows the probe head15inFIG. 1viewed from the lower side. On the other hand, the right side ofFIG. 2shows the inner structure of the post-circuit unit40. Moreover,FIG. 3shows the four probes17A to17D and the primary circuit unit30, which constitute one probe group20inFIG. 2.

As shown on the left side ofFIG. 2, the 400 probes17A to17D arranged on the probe support substrate16of the probe head15are grouped into probe groups20, each including the four probes17A to17D adjacent to each other. That is, 100 probe groups20are arranged on the probe support substrate16. Of the probe groups, four probe groups20arranged in one portion of the probe support substrate16are drawn on the left side ofFIG. 2.

Each probe group20is provided with the primary circuit unit30. In each probe group20, the primary circuit unit30is disposed in such a position that the primary circuit unit30is surrounded by the four probes17A to17D which belong to the probe group20.

The primary circuit unit30of each probe group20is electrically connected to a bus line22through a connection line21. The connection line21and the bus line22are wiring patterns formed on the probe support substrate16, for example. The bus line22extends on the probe support substrate16, and one end of the bus line22is electrically connected to the post-circuit unit40.

As shown inFIG. 3, the primary circuit unit30is provided with: a modulation circuit31; a selector switch32; pre-amplifiers33A to33D, a selector switch34; and a demodulation circuit35. Moreover, as shown on the right side ofFIG. 2, the post-circuit unit40is provided with: a recording circuit41; a serial-parallel conversion circuit42; a parallel-serial conversion circuit43; a reproduction circuit44; a buffer memory45; and a CPU (Central Processing Unit)46.

In performing a process of recording the information onto the recording surface13D of the recording medium13(information recording process), firstly, the recording circuit41inFIG. 2supplies record data, which is the information to be recorded onto the recording surface13D of the recording medium13, to the serial-parallel conversion circuit42. The record data is supplied from the recording circuit41to the serial-parallel conversion circuit42at a speed of about 1 Gbps (1 gigabits per second), for example.

The serial-parallel conversion circuit42divides the record data into 100 record data groups, and distributes the respective 100 record data groups to the 100 probe groups20, one by one. The buffer memory45is used for such a process of the serial-parallel conversion circuit42.

Each record data group is supplied to the primary circuit unit30of each probe group20through the bus line22and the connection line21from the serial-parallel conversion circuit42. The record data block is supplied simultaneously in parallel from the serial-parallel conversion circuit42to the primary circuit unit30. Moreover, each record data group is supplied from the serial-parallel conversion circuit42to the primary circuit unit30at a speed of about 10 Mbps, for example.

As shown inFIG. 3, in each probe group20, the record data group supplied to the primary circuit unit30is supplied to the modulation circuit31. The modulation circuit31converts the record data included in the record data group, to a recording signal having a waveform suitable for the recording on the recording surface13D of the recording medium13. The recording signal is outputted from the modulation circuit31to the selector switch32.

The selector switch32connects one probe of the four probes17A to17D included in each probe group20with the modulation circuit31provided for the probe group20, and changes the probe to be connected to the modulation circuit31whenever the travel direction in the reciprocation in the X direction of the recording medium13is changed. The selector switch32is electrically connected to the CPU46provided for the post-circuit unit40(refer toFIG. 2) through the connection bus21and the bus line22, and such an operation of the selector switch32is performed in accordance with a command from the CPU46.

The recording signal outputted from the modulation circuit31is supplied to any one of the probes17A to17D, in response to the operation of the selector switch32. Then, the recording signal is applied to the recording surface13D of the recording medium13through the probe. By this, the information is recorded onto the recording surface13D of the recording medium13.

On the other hand, in performing a process of reproducing the information recorded on the recording surface13D of the recording medium13(information reproducing process), in each probe group20, the selector switch34connects one probe of the four probes17A to17D included in the probe group20with the demodulation circuit35provided for the probe group20, and changes the probe to be connected to the demodulation circuit35whenever the travel direction in the reciprocation in the X direction of the recording medium13is changed. The selector switch34is electrically connected to the CPU46provided for the post-circuit unit40through the connection bus21and the bus line22, and such an operation of the selector switch34is performed in accordance with a command from the CPU46.

The information recorded on the recording surface13D of the recording medium13is read by any one of the probes17A to17D which belong to each probe group20, in response to the operation of the selector switch34. The signal read by the probe (a reading signal) is supplied to the demodulation circuit35through the selector switch34.

The demodulation circuit35converts the reading signal supplied through the selector switch34, to a reading data group. That is, the reading signal immediately after being read by the probe has an analog waveform according to an information reading method (e.g. SNDM method). The demodulation circuit35converts the reading signal to a reading data block, which is a digital binary signal. Then, the demodulation circuit35outputs the reading data block to the connection line21.

As shown inFIG. 2, the information reading by the probe and the signal conversion process by the demodulation circuit35are performed simultaneously in parallel in each probe group20. Then, the reading data block is outputted simultaneously in parallel from the demodulation circuit35in each probe group20, and is supplied to the parallel-serial conversion circuit43of the post-circuit unit40. The reading data block is supplied from demodulation circuit35to the parallel-serial conversion circuit43at a speed of about 10 Mbps, for example.

The parallel-serial conversion circuit43converts the reading data block supplied from each demodulation circuit35in parallel, to reading data which is one serial data. The buffer memory45is used for such a process of the parallel-serial conversion circuit43. The reading data is supplied from the parallel-serial conversion circuit43to the reproduction circuit44at a speed of about 1 Gbps, for example.

The reproduction circuit44performs a decoding process on the reading data. By this, the information recorded on the recording surface13D of the recording medium13is reproduced.

In the information recording process and the information reproducing process as described above, the CPU46provided for the post-circuit unit40controls the changeover of the selector switches32and34, as described above. At the same time, the CPU46also controls the driving of the actuator18.

Specifically, the CPU46controls the actuator18in each of the information recording process and the information reproducing process, to thereby reciprocate the recording medium13in the X direction. The stroke amount of the actuator18at this time is about 100 μm. The recording medium13is reciprocated by a distance of about 100 μm in the X direction.

Then, in the information recording process, the CPU46controls the actuator18and the selector switch32such that a cycle in which the recording medium13changes the travel direction in the reciprocation is synchronized with a cycle in which the selector switch32in each probe group20changes the probe to be connected to the modulation circuit31.

Moreover, in the information reproducing process, the CPU46controls the actuator18and the selector switch34such that the cycle in which the recording medium13changes the travel direction in the reciprocation is synchronized with a cycle in which the selector switch34in each probe group20changes the probe to be connected to the demodulation circuit35.

Hereinafter, each of such a process that the cycle in which the recording medium13changes the travel direction in the reciprocation is synchronized with the cycle in which the selector switch32in each probe group20changes the probe to be connected to the modulation circuit31, and such a process that the cycle in which the recording medium13changes the travel direction in the reciprocation is synchronized with the cycle in which the selector switch34in each probe group20changes the probe to be connected to the demodulation circuit35, is referred to as a “probe switching process”.

Next, an explanation will be given on the operations of the selector switch32and the actuator18in the probe switching process in the information recording process.

In the probe switching process in the information recording process, the selector switch32in each probe group and the actuator18operate as follows in accordance with the control of the CPU46, for example.

As shown inFIG. 4, firstly, the actuator18displaces the recording medium13such that the tip of each of the probes17A to17D is brought close to or in contact with the recording13D at a recording start position on the recording surface13D of the recording medium13(step S1).

Incidentally, the probe memory apparatus1is provided with another actuator which displaces the recording medium13in a parallel direction to the recording surface13D and which changes a positional relationship in the vertical direction between the recording medium13and the probes17A to17D. In the step S1, the probe memory apparatus1also drives this actuator.

Then, the selector switch32connects the probe17A with the modulation circuit31, and starts the reception of the recording signal supplied from the modulation circuit31. Then, the actuator18displaces the recording medium13in a −X direction (e.g. to the left) by 100 μm (steps S2and S3). By this, the recording signal supplied from the modulation circuit31is recorded onto the recording surface13D of the recording medium13through the probe17A.

After the recording medium13is displaced in the −X direction by 100 μm, the selector switch32stops the reception of the recording signal. Then, the selector switch32disconnects the probe17A from the modulation circuit31, and connects the probe17B with the modulation circuit31. Then, the selector switch32restarts the reception of the recording signal. Then, the actuator18displaces the recording medium13in a +X direction (e.g. to the right) by 100 μm (steps S4to S7). By this, the recording signal is recorded onto the recording surface13D of the recording medium13through the probe17B.

After the recording medium13is displaced in the +X direction by 100 μm, the selector switch32stops the reception of the recording signal. Then, the selector switch32disconnects the probe17B from the modulation circuit31, and connects the probe17C with the modulation circuit31. Then, the selector switch32restarts the reception of the recording signal. Then, the actuator18displaces the recording medium13in the −X direction by 100 μm (steps S8to S11). By this, the recording signal is recorded onto the recording surface13D of the recording medium13through the probe17C.

After the recording medium13is displaced in the −X direction by 100 μm, the selector switch32stops the reception of the recording signal. Then, the selector switch32disconnects the probe17C from the modulation circuit31, and connects the probe17D with the modulation circuit31. Then, the selector switch32restarts the reception of the recording signal. Then, the actuator18displaces the recording medium13in the +X direction by 100 μm (steps S12to S15). By this, the recording signal is recorded onto the recording surface13D of the recording medium13through the probe17D.

After the recording medium13is displaced in the +X direction by 100 μm, the selector switch32stops the reception of the recording signal. Then, the selector switch32displaces (track-shifts) the recording medium13in a +Y direction by 1 μm (steps S16and S17).

Then, the probe memory apparatus1repeats the process in the step S2to step S17until the information recording process is ended.

FIG. 5shows the scanning transition of the probes17A to17D in each probe group20when the probe switching process is performed in the information recording process, in six scenes.

InFIG. 5, points T1, T2, T3, and T4show the tips of the probes17A to17D, respectively. Arrows A1, A2, A3, and A4indicate that the recording signal is being recorded onto the recording surface13D. Moreover, the directions of the arrows A1, A2, A3, and A4indicate the travel directions of the tips of the probes17A to17D with respect to the recording surface13, respectively. Line segments L1, L2, L3, and L4indicate that the recording of the recording signal onto the recording surface13D is ended.

Incidentally,FIG. 5shows the probe memory apparatus1inFIG. 1, viewed from the top to the bottom. Thus, the placement in the vertical direction of the probes17A to17D inFIG. 5is opposite to that inFIG. 2orFIG. 3, which requires an attention. Moreover, inFIG. 5, the probes17A to17D themselves seem to be displaced on the recording medium13; however, it is the recording medium13that is actually displaced.

A scene1inFIG. 5corresponds to the step S1inFIG. 4. In the scene1, each of the tips T1to T4of the probes17A to17D is at the recording start position (left edge position of a track).

A scene2corresponds to the steps S2and S3inFIG. 4. In the scene2, each of the tip positions T1to T4of the probes17A to17D is displaced to the right edge position of the track. During the displacement, the recording signal is recorded by the probe17A. However, the recording signal is not recorded by the probes17B to17D.

A scene3corresponds to the steps S4to S7inFIG. 4. In the scene3, each of the tip positions T1to T4of the probes17A to17D is displaced to the left edge position of the track. During the displacement, the recording signal is recorded by the probe17B. However, the recording signal is not recorded by the probes17A,17C, and17D.

A scene4corresponds to the steps S8to S11inFIG. 4. In the scene4, each of the tip positions T1to T4of the probes17A to17D is displaced to the right edge position of the track. During the displacement, the recording signal is recorded by the probe17C. However, the recording signal is not recorded by the probes17A,17B, and17D.

A scene5corresponds to the steps S12to S15inFIG. 4. In the scene5, each of the tip positions T1to T4of the probes17A to17D is displaced to the left edge position of the track. During the displacement, the recording signal is recorded by the probe17D. However, the recording signal is not recorded by the probes17A to17C.

A scene6corresponds to the steps S16and S17inFIG. 4. In the scene6, each of the tip positions T1to T4of the probes17A to17D is displaced (track-shifted) to the lower side (left edge position of a next track.

As can be seen fromFIG. 5, the recording medium13reciprocates twice in the X direction. During this time, the recording medium13is not track-shifted (not displaced to change the track) in the Y direction. Moreover, while the recording medium13reciprocates twice in the X direction, the probe to record the recording signal is sequentially changed whenever the travel direction of the recording medium13is changed.

Next, an explanation will be given on the operations of the selector switch34and the actuator18in the probe switching process in the information reproducing process.

In the probe switching process in the information reproducing process, the selector switch34and the actuator18operate as follows in accordance with the control of the CPU46, for example.

As shown inFIG. 6, firstly, the actuator18displaces the recording medium13such that the tip of each of the probes17A to17D is brought close to or in contact with the recording13D at a reading start position on the recording surface13D of the recording medium13(step S21).

Then, the selector switch34connects the probe17A with the demodulation circuit35. Then, the actuator18displaces the recording medium13in the −X direction by 100 μm (steps S22and S23). By this, the information is read from the recording surface13D of the recording medium13by the probe17A, and the reading signal is supplied to the demodulation circuit35.

After the recording medium13is displaced in the −X direction by 100 μm, the selector switch disconnects the probe17A from the demodulation circuit35, and connects the probe17B with the demodulation circuit35. Then, the actuator18displaces the recording medium13in the +X direction by 100 μm (steps S24and S25). By this, the information is read from the recording surface13D of the recording medium13by the probe17B, and the reading signal is supplied to the demodulation circuit35.

After the recording medium13is displaced in the +X direction by 100 μm, the selector switch34disconnects the probe17B from the demodulation circuit35, and connects the probe17C with the demodulation circuit35. Then, the selector switch32restarts the reception of the recording signal. Then, the actuator18displaces the recording medium13in the −X direction by 100 μm (steps S26and S27). By this, the information is read from the recording surface13D of the recording medium13by the probe17C, and the reading signal is supplied to the demodulation circuit35.

After the recording medium13is displaced in the -X direction by 100 μm, the selector switch34disconnects the probe17C from the demodulation circuit35, and connects the probe17D with the demodulation circuit35. Then, the actuator18displaces the recording medium13in the +X direction by 100 μm (steps S28and S29). By this, the information is read from the recording surface13D of the recording medium13by the probe17D, and the reading signal is supplied to the demodulation circuit35.

After the recording medium13is displaced in the +X direction by 100 μm, the actuator18displaces (track-shifts) the recording medium13in the +Y direction by 1 μm (steps S30).

Then, the probe memory apparatus1repeats the process in the step S22to step S30until the information reproducing process is ended.

The scanning transition of the probes17A to17D in each probe group20when the probe switching process is performed in the information reproducing process is the same as that in the information recording process (refer toFIG. 5).

As explained above, in the probe memory apparatus1, in each probe group20, the probe to be connected to the modulation circuit31or the demodulation circuit35is changed whenever the travel direction in the reciprocation in the X direction of the recording medium13is changed.

Therefore, as shown inFIG. 3, it is only necessary to provide each probe group20with one primary circuit unit30including the modulation circuit31and the demodulation circuit35or the like. That is, only one primary circuit unit30may be assigned to the four probes17A to17D. In other words, it is unnecessary to assign one primary circuit unit30to one probe. Thus, it is possible to reduce the number of the primary circuit units30to be disposed on the probe support substrate16of the probe head15.

Thus, even if the number of the probes17A to17D is large and the interval of the adjacent probes is small, it is possible to ensure a space to dispose the primary circuit units30on the probe support substrate16.

Therefore, it is possible to increase the number of the probes17A to17D, and to reduce the interval of the probes adjacent to each other in the X direction. Hence, it is possible to reduce the stroke amount of the actuator18for displacing the recording medium13in the X direction. Thus, it is possible to respond to the requirements, such as increasing the information recording speed and the information reading speed, limiting or controlling power consumption by the driving of the actuator18, and reducing the size of the probe memory apparatus1, in a balanced manner, and it is possible to increase the performance of the probe memory apparatus1.

Moreover, on the probe memory apparatus1, in each probe group20, the probe to be connected to the demodulation circuit35is changed whenever the travel direction in the reciprocation in the X direction of the recording medium13is changed.

By this, in the information reproducing process, it is possible to reduce the number of read data, which is supplied simultaneously in parallel to the parallel-serial conversion circuit43.

That is, if the information recorded on the recording surface13D of the recording medium13is simultaneously read using all the probes17A to17D disposed on the probe head15, 400 read data is supplied simultaneously in parallel from the 400 probes17A to17D to the parallel-serial conversion circuit43. As a result, in order to perform a conversion process on the parallel-serial conversion circuit43, it is unnecessary to increase he memory capacity of the buffer memory45.

According to the probe memory apparatus1, however, in each probe group20, since the probe to be connected to the demodulation circuit35is changed whenever the travel direction in the reciprocation in the X direction of the recording medium13is changed, there will be 100 read data (read data group), which is supplied simultaneously in parallel to the parallel-serial conversion circuit43. That is, as compared to the total number (400) of the probes17A to17D disposed on the probe head15, the total number (100) of the read data (read data group) supplied to the parallel-serial conversion circuit43can be small. Therefore, it is possible to reduce the memory capacity of the buffer memory45used to perform the conversion process on the parallel-serial conversion circuit43.

Second Embodiment

FIG. 7shows a post-circuit unit and a probe head of a scanning probe memory apparatus in a second embodiment of the information recording/reproducing apparatus of the present invention. Incidentally, inFIG. 7, the same constituent elements as those shown inFIG. 2carry the same numerical references.

In the information recording process, a CPU51provided for the post-circuit unit50inFIG. 7controls the selector switch32in each probe group20to change the probe to be connected to the modulation circuit31whenever the recording medium13reciprocates once in the X direction. That is, the CPU51synchronizes a cycle in which the recording medium13reciprocates once with a cycle in which the selector switch32in each probe group20changes the probe to be connected to the modulation circuit31.

On the other hand, in the information reproducing process, the CPU51controls the selector switch34in each probe group20to change the probe to be connected to the demodulation circuit35whenever the recording medium13reciprocates once in the X direction. That is, the CPU51synchronizes the cycle in which the recording medium13reciprocates once with a cycle in which the selector switch34in each probe group20changes the probe to be connected to the demodulation circuit35.

In the second embodiment, for example, the information recorded on the recording surface13D is deleted using the probe17A while the recording medium13is displaced by 100 μm in the −X direction, and then the information is recorded using the probe17A while the recording medium13is displaced by 100 μm in the +X direction. Then, while the probe is changed whenever the recording medium13reciprocates once, such information deletion and information recording are repeated. In this case, the recording medium13repeats such a motion that it reciprocates four times in the X direction and then track-shifts once in the Y direction.

Even in the second embodiment, it is possible to achieve substantially the same effect as that in the first embodiment.

Third Embodiment

FIG. 8shows a post-circuit unit and a probe head of a scanning probe memory apparatus in a third embodiment of the information recording/reproducing apparatus of the present invention. Incidentally, inFIG. 8, the same constituent elements as those shown inFIG. 2carry the same numerical references.

In the information recording process, a CPU61provided for the post-circuit unit60inFIG. 8controls the selector switch32in each probe group20to change the probe to be connected to the modulation circuit31whenever the recording medium13reciprocates 1.5 times in the X direction. That is, the CPU61synchronizes a cycle in which the recording medium13reciprocates 1.5 times with a cycle in which the selector switch32in each probe group20changes the probe to be connected to the modulation circuit31.

On the other hand, in the information reproducing process, the CPU61controls the selector switch34in each probe group20to change the probe to be connected to the demodulation circuit35whenever the recording medium13reciprocates 1.5 times in the X direction. That is, the CPU61synchronizes the cycle in which the recording medium13reciprocates 1.5 times with a cycle in which the selector switch34in each probe group20changes the probe to be connected to the demodulation circuit35.

In the third embodiment, the recording medium13repeats such a motion that it reciprocates six times in the X direction and then track-shifts once in the Y direction.

Even in the third embodiment, it is possible to achieve substantially the same effect as that in the first embodiment.

Fourth Embodiment

FIG. 9shows a post-circuit unit and a probe head of a scanning probe memory apparatus in a fourth embodiment of the information recording/reproducing apparatus of the present invention. Incidentally, inFIG. 9, the same constituent elements as those shown inFIG. 2carry the same numerical references.

In the information recording process, a CPU71provided for the post-circuit unit70inFIG. 9controls the selector switch32in each probe group20to change the probe to be connected to the modulation circuit31whenever the recording medium13reciprocates n times (n is an integer of 2 or more) in the X direction. That is, the CPU71synchronizes a cycle in which the recording medium13reciprocates n times with a cycle in which the selector switch32in each probe group20changes the probe to be connected to the modulation circuit31.

On the other hand, in the information reproducing process, the CPU71controls the selector switch34in each probe group20to change the probe to be connected to the demodulation circuit35whenever the recording medium13reciprocates n times in the X direction. That is, the CPU71synchronizes the cycle in which the recording medium13reciprocates 1.5 times with a cycle in which the selector switch34in each probe group20changes the probe to be connected to the demodulation circuit35.

Even in the fourth embodiment, it is possible to achieve substantially the same effect as that in the first embodiment.

Fifth Embodiment

FIG. 10shows a post-circuit unit and a probe head of a scanning probe memory apparatus in a fifth embodiment of the information recording/reproducing apparatus of the present invention. Incidentally, inFIG. 10, the same constituent elements as those shown inFIG. 2carry the same numerical references.

In the information recording process, a CPU81inFIG. 10controls the selector switch32, to thereby connect the probe17A in each probe group20with the modulation circuit31when the recording medium13is displaced in a predetermined section during an outward journey, and connect the probe17B in each probe group20with the modulation circuit31when the recording medium13is displaced in the predetermined section during a homeward journey.

On the other hand, in the information reproducing process, the CPU81controls the selector switch34, to thereby connect the probe17A in each probe group20with the demodulation circuit35when the recording medium13is displaced in the predetermined section during the outward journey, and connect the probe17B in each probe group20with the demodulation circuit35when the recording medium13is displaced in the predetermined section during the homeward journey.

For example, in the information recording process, under the control of the CPU81, the selector switch32and the actuator18operate as shown inFIG. 11.

Firstly, each of the tips T1to T4of the respective probes17A to17D is at the recording start position (left edge position of each track). Then, the selector switch32connects the probe17A with the modulation circuit31(Scene1).

Then, the actuator18displaces the recording medium13in the −X direction by 50 μm. By this, each of the tip positions T1to T4of the probes17A to17D is displaced to the intermediate position of each track. During the displacement, the recording signal is recorded by the probe17A (Scene2).

Then, the selector switch32disconnects the probe17A from the modulation circuit31and connects the probe17B with the modulation circuit31. Then, the actuator18further displaces the recording medium13in the −X direction by 50 μm. By this, each of the tip positions T1to T4of the probes17A to17D is displaced to the right edge position of each track. During the displacement, the recording signal is recorded by the probe17B (Scene3).

Then, the selector switch32disconnects the probe17B from the modulation circuit31and connects the probe17A with the modulation circuit31. Then, the actuator18further displaces the recording medium13in the +X direction by 50 μm. By this, each of the tip positions T1to T4of the probes17A to17D is displaced to the intermediate position of each track. During the displacement, the recording signal is recorded by the probe17A (Scene4).

Then, the selector switch32disconnects the probe17A from the modulation circuit31and connects the probe17B with the modulation circuit31. Then, the actuator18further displaces the recording medium13in the +X direction by 50 μm. By this, each of the tip positions T1to T4of the probes17A to17D is displaced to the left position of each track. During the displacement, the recording signal is recorded by the probe17B (Scene5).

As described above, in the information recording process, when the probes17A and the probe17B are displaced in the predetermined section from the left edge position to the intermediate position of the tracks due to the displacement in the −X direction of the recording medium13, the selector switch32connects the probe17A with the modulation circuit31. On the other hand, when the probes17A and the probe17B are displaced in the predetermined section from the intermediate position to the left edge position of the tracks due to the displacement in the +X direction of the recording medium13, the selector switch32connects the probe17B with the modulation circuit31.

In the same manner, when the probes17A and the probe17B are displaced in the predetermined section from the intermediate position to the right edge position of the tracks due to the displacement in the −X direction of the recording medium13, the selector switch32connects the probe17B with the modulation circuit31. On the other hand, when the probes17A and the probe17B are displaced in the predetermined section from the right edge position to the intermediate position of the tracks due to the displacement in the +X direction of the recording medium13, the selector switch32connects the probe17B with the modulation circuit31.

Even in the fifth embodiment, it is possible to achieve substantially the same effect as that in the first embodiment.

Incidentally, in the explanation of each embodiment described above, such a case is taken as an example that the linear tracks are formed in the X direction on the recording surface13D; however, the present invention is not limited to this. The shape of the track may be arced or meandering.

Moreover, in the explanation of each embodiment described above, such a case is taken as an example that the four probes17A to17D are grouped to form one probe group20; however, the present invention is not limited to this. Two, three, or five or more probes may be grouped to form one probe group.

Moreover, in the explanation of each embodiment described above, such a case is taken as an example that the four probes17A to17D which are adjacent to each other and which are arranged in a matrix are grouped to form one probe group20; however, the present invention is not limited to this. The four probes17A to17D which are arranged on a line may be grouped to form one probe group.

Moreover, the probes used to form one probe group are not necessarily adjacent to each other. For example, a probe which does not belong to the same probe group can be disposed between two probes which belong to the same probe group.

Moreover, in the explanation of each embodiment described above, such a case is taken as an example that the plurality of probe groups20are arranged on the probe head15; however, the present invention can be also applied to the case where the probe head is provided with one probe group. In this case, in the probe group, the probe to be connected to the demodulation circuit is changed whenever the travel direction in the reciprocation of the recording medium is changed, so that the read data outputted from the demodulation circuit is serial data. Moreover, because there is only one probe group, it is only necessary to supply the post-circuit unit with the read data outputted from the demodulation circuit in this probe group. Therefore, it is possible to eliminate the parallel-serial conversion circuit and the buffer memory necessary for the parallel-serial conversion.

In the explanation of each embodiment described above, such a case is taken as an example that the cycle in which the recording medium13changes the travel direction in the reciprocation is synchronized with the cycle in which the selector switch32or34in each probe group20changes the probe. However, if the probe change by the selector switch is performed during the displacement control of the recording medium, the cycle in which the recording medium changes the travel direction is not necessarily synchronized with the cycle in which the selector switch changes the probe. For example, the cycle in which the recording medium changes the travel direction is not necessarily synchronized with the cycle in which the selector switch changes the probe, if the scanning is performed on one track more than twice, such as a case where the information already recorded in a certain track of the recording medium is deleted and then another information is recorded into the track and a case where the information is recorded onto the information recording medium and then the content of the recorded information is confirmed.

Moreover, in the explanation of each embodiment described above, such a case is taken as an example that the primary circuit unit30including the selector switches32and34is disposed in such a position that the primary circuit unit30is surrounded by the four probes17A to17D; however, the present invention is not limited to this. The primary circuit unit30may be disposed between the two probes adjacent to each other.

Moreover, in the explanation of each embodiment described above, such a case is taken as an example that the primary circuit unit30including the selector switches32and34is disposed in such a position that the primary circuit unit30is surrounded by the four probes17A to17D; however, the present invention is not limited to this. The primary circuit unit30may be disposed between the two probes adjacent to each other.

Moreover, in the explanation of each embodiment described above, such a case is taken as an example that the information recording principle is used in which the recording medium13having the recording layer13C formed of the ferroelectric material is used and the polarization direction of the ferrorelectric substance is changed to thereby record the information and that the SNDM method is used as the information reproduction principle. However, the information recording principle and the information reproduction principle that can be adopted in the information recording/reproducing apparatus of the present invention is not limited to this. It is possible to adopt various information recording principles and information reproduction principles, such as using a tunnel effect, using an atomic force, using a magnetic force, using an electrostatic force, using a non-linear dielectric constant, and using heat deformation of a recording medium.

Moreover, the CPU46inFIG. 2and the selector switches32and34inFIG. 3are a specific example of the changing device. Moreover, the CPU51inFIG. 7and the selector switches32and34inFIG. 3are another specific example of the changing device. Moreover, the CPU61inFIG. 8and the selector switches32and34inFIG. 3are another specific example of the changing device. Moreover, the CPU71inFIG. 9and the selector switches32and34inFIG. 3are another specific example of the changing device. Moreover, the CPU81inFIG. 10and the selector switches32and34inFIG. 3are another specific example of the changing device. Moreover, the modulation circuit31and the demodulation circuit35inFIG. 3are a specific example of the signal processing circuit.

Moreover, in the present invention, various changes may be made, if desired, without departing from the essence or spirit of the invention which can be read from the claims and the entire specification. An information recording/reproducing apparatus, which involves such changes, is also intended to be within the technical scope of the present invention.

INDUSTRIAL APPLICABILITY

The information recording/reproducing apparatus according to the present invention can be applied to an information recording/reproducing apparatus for recording or reproducing information with respect to an information recording medium, using a plurality of probes, such as a scanning probe memory apparatus, for example.