JPH04258826A - Information recording and/or reproducing device - Google Patents

Abstract

PURPOSE:To improve driving accuracy for a probe mounted on the movable part and to attain high speed driving by supporting a frame with parallel springs within a frame-shaped base and also supporting the movable part with parallel springs within the frame. CONSTITUTION:The frame 41 is supported inside of the frame-shaped base 40 through elastic hinge springs 42, and further the movable part 43 mounted with a probe electrode is supported inside of the frame 41 through elastic hinge springs 44. Then, a piezoelectric element 45 for the y-direction and a piezoelectric element 46 for the x-direction are mounted, thereby the movable part 43 is driven in the x,y-directions. As a result, the movement of movable part 43 can be made independently in two axial directions, therefore, the accuracy of positional control for writing/reading is high, and a high speed scanning is easily made, then the error for writing/reading is reduced.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording and/or reproducing apparatus for recording information on and reproducing information from a recording medium using needle-like electrodes.

0002

2. Description of the Related Art In recent years, research has been progressing on information recording and reproducing devices that apply the principles of scanning tunneling microscopes. A scanning tunneling microscope (hereinafter referred to as STM) was developed, and
G. Binnig et al. , Helvetica
Physica Acta. ,55,726(198
2)], it has become possible to perform measurements with high resolution in real space, regardless of whether it is single crystal or amorphous. STM utilizes the fact that a tunnel current flows when a voltage is applied between a metal probe and a conductive substance and the probe is brought close to a distance of about 1 nm. This current is very sensitive to changes in the distance between the two, so by scanning the probe while keeping the tunneling current constant, it is possible to measure a real space image of the surface of a conductive material with high resolution. .

Although measurement using STM is limited to conductive materials, it is also beginning to be applied to structural analysis of thin insulating films formed on the surfaces of conductive materials. Furthermore, since STM uses a method of detecting minute currents, it has the advantage of not damaging the measurement material and allowing observation with low power. Also,
It operates not only in ultra-high vacuum, but also in the atmosphere and in solvents, and can be used with a variety of materials, so it is expected to have a wide range of applications.

[0004] An information recording and/or reproducing device that uses STM to write and retrieve information at high density during use has a fine movement mechanism for finely moving the probe tip, that is, the probe electrode, in the x and y directions. It is used. Conventional fine movement mechanisms include a single push type in which a piezoelectric element is placed only on one side of the movable part, and a drive type in which a pair of piezoelectric elements with opposite expansion and contraction characteristics are placed on both sides of the movable part, with opposite phases. It is broadly divided into double push type that applies voltage.

[0005] FIG. 4 is a plan view showing a one-sided push type, which has a two-degree-of-freedom fine movement mechanism using an integral notched spring mechanism. The member 1 is divided into an L-shaped fixed part 1a and other parts by a notch, and a first movable part is connected to the inside of the arm of the fixed part 1a parallel to the x direction via two links 1b parallel to the y direction. The portion 1c is supported, and the movable portion 1c is movable in the x direction with respect to the fixed portion 1a. This movable part 1
A second movable portion 1e is supported inside the arm parallel to the y direction of a through two links 1d parallel to the x direction. A piezoelectric element 2 is attached between the tip of the fixed part 1a in the y direction and the first movable part 1c, and the expansion and contraction of the piezoelectric element 2 drives the first movable part 1c in the x direction. Moreover, a piezoelectric element 3 is attached in the first movable part 1c and the second movable part 1e, and the expansion and contraction of the piezoelectric element 3 causes the second movable part 1e to move in the y direction with respect to the first movable part 1c. Driven. In this mechanism, the second movable part 1e can be moved within the xy plane with respect to the fixed part 1a by voltage applied to the piezoelectric elements 2 and 3.

FIG. 5 is a perspective view of a double push type fine movement mechanism, in which the probe 10 includes a piezoelectric element 11a that expands and contracts in the x direction;
11b is attached to both sides in the x direction, piezoelectric elements 12a and 12b that expand and contract in the y direction are attached to both sides in the y direction, and a piezoelectric element 13 that expands and contracts in the z direction is attached from above. The other ends of the piezoelectric elements 11 to 13 are fixed to a fixed part (not shown). The probe 10 can be driven in the xy parallel plane by the voltage applied to the piezoelectric elements 11 and 12.

[0007]

[Problems to be Solved by the Invention] However, in the single-push type fine movement mechanism, displacement deviation due to temperature drift of the piezoelectric elements 2 and 3 tends to occur, and if the temperature is controlled with high precision to prevent this, the entire device will become huge. It is not easy to electrically correct temperature drift. In addition, in the case of the double push type, the temperature drift is canceled out, but since the piezoelectric elements 11 and 12 are directly connected to the probe 10, the drives in the x and y directions are not completely independent.
Accurate positioning is not possible and it is not suitable for high-speed scanning. Both fine movement mechanisms have the problem that it is difficult to strengthen their rigidity.

An object of the present invention is to provide information recording in which there is no displacement of the movable part due to temperature drift of the piezoelectric element, the two axial directions are driven independently within the same plane, and the rigidity of the drive mechanism can be easily strengthened. and/or to provide a reproduction device.

[0009]

[Means for Solving the Problems] An information recording and/or reproducing apparatus according to the present invention for achieving the above object includes a probe electrode for writing and reading, and a recording medium provided opposite to the probe electrode. The first movable part is moved relative to the fixed part that records and/or reproduces information.
a first spring that guides in the axial direction of the first piezoelectric element, a first piezoelectric element provided on the fixed part facing in series in the first axial direction with the first movable part in between; 2nd to the movable part
a second spring that guides the movable part in the second axial direction; and a second spring provided on the first movable part facing in series in the second axial direction with the second movable part in between. The probe or the recording medium is held in a second movable part of a fine movement mechanism comprising a piezoelectric element.

0010

[Operation] The information recording and/or reproducing device having the above-mentioned configuration moves and positions the second movable part in the first axial direction via the first movable part by applying a voltage to the first piezoelectric element. The second movable part is moved and positioned in the second axial direction by the voltage applied to the second piezoelectric element, and the second
The relative position of the probe or the recording medium held by the movable part of is changed.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail based on the embodiments shown in FIGS. 1 to 3.

FIG. 1 is a configuration diagram of an information recording and/or reproducing apparatus, in which a recording medium 22 is placed on an xy direction coarse movement mechanism 21, and coarse movement within the xy plane is possible. A z-direction fine movement coarse movement mechanism 23 is arranged above this, and an xy-direction fine movement mechanism 24 attached to the driven part on the lower surface is a probe electrode 2 made of tungsten made by electrolytic polishing.
The tip of the probe electrode 25 is close to the surface of the recording medium 22. The recording medium 22 is made by vacuum-depositing gold (Au) using chromium as an undercoat layer on a substrate 26 made by polishing glass to form a base electrode 27.
Thereon a recording layer 28 made of graphite (HOPG)
are bonded together with a conductive adhesive, and the recording/reproducing area on the surface of the recording layer 28 is smoothed on the atomic order by cleavage. On the other hand, an interface 29 for connecting the information recording and/or reproducing apparatus to a host device is connected to the drive mechanism, recording medium 22, and probe electrode 25 via the following electric circuit. That is, a control circuit 30 performs centralized control of mutual operations between blocks in the information recording and/or reproducing apparatus, and a write/read circuit 31 writes/reads write/read data according to instructions from the control circuit 30.
, a voltage application circuit 32 that applies a pulse voltage between the x direction and the y direction to write data based on the signal from the write/read circuit 31, and applies a read voltage during reading.
, amplifies the current flowing between the x direction and the y direction, and sends this as a read information signal to the write/read circuit 31 when reading out the voltage amplifying circuit 33 according to instructions from the control circuit 30, etc. x based on the signal of the position detection circuit
A positioning circuit 34 that determines the position in the direction and y direction, a servo circuit 35 that servo controls the position in the x direction and y direction based on the servo signal from the positioning circuit 34, and fine and coarse movement in the z direction according to the signal of the servo circuit 35. xy according to the signals from the z-direction drive circuit 36 and servo circuit 35 that drive the mechanism 23
x that drives the direction fine movement mechanism 24 and the xy direction coarse movement mechanism 21
A y-direction drive circuit 37 and a position detection circuit 38 for detecting relative positions in the x and y directions are provided.

Next, the configuration of the xy direction fine movement mechanism 24 is shown in FIG.
The explanation will be based on the plan view. Z-direction fine and coarse movement mechanism 23
A frame-shaped frame 41 is similarly supported via an elastic hinge spring 42 parallel to the x-direction on the inside of a frame-shaped base 40 supported movably in the z-direction perpendicular to the plane of the paper, and a square movable part 43 is an elastic hinge spring 4 parallel to the y direction
4 is supported inside the frame 41. The elastic hinge springs 42 are attached in pairs parallel to the y-axis between the base 40 and the frame 41 to form parallel springs, and allow the frame 41 to move slightly in the y direction with respect to the base 40. Similarly, the spring 44 is a part between the movable part 43 and the frame 41 parallel to the x-axis, and is located between the frame 4
1, the movable part 43 can be moved slightly in the x direction. Further, in the two gaps between the base 40 and the frame 41 parallel to the x-axis, a y-direction piezoelectric element 45a that can be expanded and contracted in the y-direction,
45b are sandwiched between the frame 41 and the movable part 43.
X-direction piezoelectric elements 46a and 46b, which can be expanded and contracted in the x-direction, are sandwiched between two gaps parallel to the y-axis of the y-axis. The probe electrode 25 shown in FIG. 1 is attached to the movable part 43 and driven, and the movable part 43 is
To move in the positive direction, two x-direction piezoelectric elements 46a are used.
, 46b, a voltage with a polarity such that it expands is applied to the x-direction piezoelectric element 46a located on the negative side of the x-direction,
A voltage is applied to the x-direction piezoelectric element 46b located on the positive side of the direction so as to reduce the size. For example, the movable part 43 may be
When moving in the positive direction, the y-direction piezoelectric element 45a
By applying a voltage in the direction of contraction to the piezoelectric element 45b and applying a voltage to the piezoelectric element 45b so as to make it expand, the frame 41 is moved to the positive side in the y direction, so that the movable part 43 is also moved in the y direction. In this way, the movable portion 43 can be driven by the piezoelectric elements 45 and 46 independently in the x direction and the y direction by the elastic hinge springs 42 and 44.

Next, the operation of the information recording and/or reproducing apparatus will be explained. In order to avoid contact with the recording medium 22, the probe electrode 25 is initially positioned slightly above the probe electrode 25, and is brought close to the recording medium 22 by the z-direction fine and coarse movement mechanism 23 during use. At this time, a read voltage of 200 mV is applied between the probe electrode 25 and the base electrode 27 of the recording medium 22 by the voltage application circuit 32, and the probe electrodes 25 and the base electrode 27 of the recording medium 22 are brought close together until the current detected by the current amplification circuit 33 reaches 100 pA. The z-direction fine movement mechanism 23 is held, and then the xy-direction fine movement mechanism 2 is held.
4 to scan the recording medium 22 for recording and reproduction. Recording is performed by applying a pulsed voltage from the voltage application circuit 32 at a write position commanded by the control circuit 30 while scanning the recording area of the recording medium 22 one row at a time with the probe electrode 25 . This pulsed voltage has a pulse height of 4
V and a pulse width of 1 μS, which is the threshold value for the part of the graphite film to which voltage is applied to change into a concave shape. Reproduction is performed using the voltage application circuit 32 between the probe electrode 25 and the base electrode 2.
x while applying a reading voltage of 200 mV during 7
The recording area is scanned with the probe electrode 25 using the y-direction fine movement mechanism 24, and reading is performed from changes in the current in the current amplification circuit 33. In the experiment, the natural frequency of the movable part 43 in the x direction was approximately 3 kHz, and the natural frequency in the y direction was approximately 1.5.
It was kHz. Also, the recording bit size is 4 nm in diameter.
The write and read conditions are not limited to the above example.

FIG. 3 shows the xy direction fine movement mechanism 2 of the second embodiment.
4 shows a top view of the elastic hinge spring 42 of the first embodiment.
, 44 are replaced by parallel leaf springs 51, 52. A frame 41 is supported movably in the y direction inside the base 40 via two sets of parallel plate springs 51, and is coupled in the y direction by y direction piezoelectric elements 45a and 45b, so that it can be driven in the y direction. The movable portion 43 inside the frame 41 is movable in the x direction by a parallel plate spring 52, and is driven in the x direction by x direction piezoelectric elements 46a and 46b. The recording medium (not shown) is made by epitaxially growing gold on a smooth substrate obtained by cleaving mica, and stacking 8 layers of squarylium-bis-6-octylazulene, which has an electric memory effect, by the LB method. ing. The rest of the configuration is the same as the first embodiment, and in this embodiment, positioning accuracy is improved compared to the conventional one, and write/read errors caused by this are improved.

In all of the embodiments described above, the movable portion 43, that is, the probe electrode 25, is finely moved in the x and y directions independently on the x and y axes, so that positioning accuracy is improved and high-speed scanning is possible.

In the embodiment, x
Although the y-direction fine movement mechanism is used, it may also be used as an STM scanning mechanism.

[0018]

As explained above, in the information recording and/or reproducing apparatus according to the present invention, since the movable part can be moved independently in two axial directions, the accuracy of position control for writing and reading is high. High-speed scanning is easy and there are fewer write/read errors.

[Brief explanation of the drawing]

FIG. 1 is a block circuit configuration diagram of a first embodiment.

FIG. 2 is a plan view of the xy direction fine movement mechanism.

FIG. 3 is a plan view of the xy direction fine movement mechanism of the second embodiment.

FIG. 4 is a plan view of a conventional single-push type fine movement mechanism.

FIG. 5 is a plan view of a conventional double push type fine movement mechanism.

[Explanation of symbols]

40 base 41 Frame 42, 44 Elastic hinge spring 43 Movable part 45 y-direction piezoelectric element 46 x direction piezoelectric element 51, 52 Parallel leaf spring

Claims (5)

[Claims] Claim 1: A first movable part is connected to a fixed part that records and/or reproduces information by relatively moving a probe electrode that performs writing and reading and a recording medium provided opposite to the probe electrode. a first spring guided in the axial direction of the first piezoelectric element; a first piezoelectric element provided on the fixed part facing in series in the first axial direction with the first movable part in between; a second spring that guides the second movable part in the second axial direction with respect to the movable part; and a second spring that faces the second movable part in series in the second axial direction with the second movable part in between. The second part provided in the movable part
An information recording and/or reproducing apparatus characterized in that the probe or the recording medium is held in a second movable part of a fine movement mechanism comprising a piezoelectric element. 2. The information recording and/or reproducing apparatus according to claim 1, wherein the second axis direction is a main scanning direction. 3. The information recording and/or reproducing apparatus according to claim 1, wherein the spring is a leaf spring. 4. The information recording and/or reproducing apparatus according to claim 1, wherein the spring is an elastic hinge spring. 5. Claim 1, wherein the piezoelectric element is of a laminated type.
The information recording and/or reproducing device described in .