JPH09306044A - Information recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a light weight and highly accurate head-medium distance control head by measuring the contact time between the cantilever provided on a head part and the projected part provided on the surface of a recording medium and detecting the distance between the head and the recording medium. SOLUTION: A recording and reproducing head 1 is arranged by being faced to a recording medium. Projected parts 7 are provided on one part of the surface of the recording medium and also two cantilevers 2, 3 are mounted on the head 1 and the cantilever 3 is made contactable with the projected parts 7. When the head 1 is scanned in the horizontal direction, the distance control cantilever 3 is brought into contact with the slope 11 of the projected part 7 and this contact continues until it passes the part 7. At this point, an energizing current 13 is detected in between the cantilever 3 and an electric layer and a distance from a detecting needle to the medium is calculated from an energizing time. Thus, the head-medium distance is substantially controlled constant by controlling the height of the head 1 with respect to the surface of the medium so that the contact time between the lever 3 and the part 7 becomes constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to high-speed and high-accuracy distance control between a head of an information recording / reproducing apparatus and a recording medium, and simple and lightweight head.

[0002]

2. Description of the Related Art Conventionally, distance control between head recording media of an information recording / reproducing apparatus has been carried out by using distance detection by an optical head and flying by a slider. Further, in an information recording / reproducing apparatus using a scanning probe typified by a scanning tunneling microscope and a scanning atomic force microscope, the head recording medium distance control is performed by detecting the tunnel current flowing through the probe and the force received by the probe. Was going on.

[0003]

In the above conventional example, it is necessary to equip the head with a complicated distance detection sensor for detecting the distance for controlling the distance between the recording media of the heads, which leads to miniaturization and weight reduction of the head. Is a disadvantage. Due to this, the high-accuracy and high-speed control of the head is also restricted. In order to increase the accuracy and speed of the head recording medium distance control, it is necessary to reduce the weight of the head recording medium distance detection mechanism and to simplify the weight of the head.

[0004]

According to the present invention, in an information recording / reproducing apparatus having a head and a recording medium, a simple structure of a function of detecting a distance between head recording media in addition to an original information recording / reproducing function of a head portion is provided. Have. For this function, a cantilever is provided, and convex portions are provided on the surface of the recording medium at predetermined intervals apart from the information to be recorded or reproduced, and the contact time between the cantilever and the convex portion is measured to determine the distance between the head recording media. Detect. Further, in order to detect the contact, the current flowing between the cantilever and the convex portion is detected.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In an information recording / reproducing apparatus having a head and a recording medium, the head must run while keeping the distance between the head and the recording medium substantially constant. The head of the present invention is provided with a cantilever at the tip thereof for the purpose of detecting the distance between recording media, in addition to the original information recording / reproducing function. When the head is running during recording / reproduction, in the flat information recording portion of the recording medium, the cantilever intended to detect the distance between the recording media does not come into contact with the recording medium, but reaches the convex portion on the recording medium. Then, the cantilever contacts the protrusion. The contact surface of the convex part with which the cantilever contacts is a slope with a predetermined inclination angle, and the time when the head leaves the preceding convex part and approaches the next convex part and the cantilever starts to touch the slope is shorter as the head-medium distance is shorter. Become. Furthermore, the time during which the cantilever touches the slope becomes longer. Therefore, by measuring the time for which the cantilever contacts the protrusion,
The head-to-medium distance is required. As a method of detecting this contact, a voltage is applied between the head and the medium, and the current flowing by the contact is detected.

In the flat information recording portion of the recording medium, the cantilever provided for the original information recording / reproducing function performs the information recording / reproducing operation. This cantilever also comes into contact with the convex portion as a matter of course, but since the convex portion and the information recording / reproducing area are of course different in the structure of the recording medium, this adversely affects the operation of information recording / reproducing. Never give. Even with the same structure, the contact time with the convex portion is a long time which is extremely different from the size of one unit of information, and this can be used to remove it from the signal.

EXAMPLE An example in which the present invention is applied to an energized phase change recording / reproducing apparatus using an atomic force microscope probe will be described. The original recording operation of this recording / reproducing apparatus is to form a phase-change recording mark by bringing a cantilever, which is an atomic force microscope probe, into contact with a phase-change film, which is a recording medium, and conducting electricity. Further, the original reproducing operation is to electrically detect the change in the electric resistance of the recording mark through the cantilever.

In the present embodiment, in addition to the original recording / reproducing function, a cantilever for detecting the distance between the head media is provided adjacent to the cantilever which is an atomic force microscope probe.

FIG. 1 is a conceptual diagram showing a basic structure of a head of a recording / reproducing apparatus according to an embodiment of the present invention. The head 1 has two cantilevers, a cantilever 2 for recording / reproducing and a cantilever 3 for capturing information for distance control. Each of the two cantilevers has a probe at the tip, and the cantilevers are arranged adjacent to each other with a spacing of 10 μm. Regarding the length of the cantilever, the distance control cantilever 3 is shorter than the recording / reproducing cantilever 2 for recording / reproducing by 2 μm. These cantilevers are made of, for example, silicon nitride, and their surfaces are coated with the Pt layer 4. The Pt layer 4 serves as a wiring for connecting the probe of each cantilever to a control system (not shown), and electric signals flowing through each cantilever can be individually extracted. In the present embodiment, the tip of the cantilever may be sharply pointed and the tip probe may be omitted.

FIG. 2 is a diagram showing an example of the structure of a recording medium to which the present invention is applicable, in the form of a perspective view with a cross section. The substrate 5 of the recording medium is produced on the glass substrate 6 by the 2P method,
On the surface of this substrate, a Pt electrode layer 8 having a thickness of 20 nm,
As the recording layer 9, a 20 nm thick phase change film GeSbTe layer is formed. Substrate 5, Pt electrode layer 8 and recording layer 9
The stripe-shaped convex portions 7 are periodically formed on the.
The convex portions 7 are isosceles triangles having a base length of 200 nm and a height of 100 nm, and are provided at intervals of 1 μm. The length of the stripe is 1 mm. The convex portion 7 and the area around this are
It is only used for detecting the distance between the head media, and the original information recording is performed in a flat area other than this area.

This recording medium is set in an atomic force microscope, and the head 1 is attached to a raster scan actuator (not shown) held in a casing as an atomic force microscope main body, and recording / reproducing is performed. In this embodiment, when moving on the track, the recording medium and the head 1 are X-shaped as shown in FIG.
When moving in a different direction and moving in different directions, it is assumed that the track moves in the Y direction.

FIG. 3 is a conceptual diagram for explaining the mechanism of distance control for controlling the distance between head media to be constant. The head 1 is provided with Z, X and Y actuators (Y direction is a direction perpendicular to the paper surface in the example of the drawing) shown by 14, 15 and 16, respectively, and is supported by a housing as an atomic force microscope main body. Two cantilevers 2 and 3 are mounted on the head 1. Therefore, these cantilevers can be moved in the X direction and the Y direction (scanning of the head) by the actuators 15 and 16, and the actuator 14 can control the Z direction, that is, the distance between the head media.

To control the relative movement between the head media, not only the actuator shown in FIG. 3 but also an actuator for moving the medium itself may be provided. Of course, both may be provided, and one may be classified as coarse movement and the other as fine movement.

The distance a from the tip of the distance control cantilever 3 to the recording medium is set to 50 nm, and the head 1 is scanned in the X direction at a speed of 10 μm / s. At this time, when the head 1 is in the flat portion of the recording medium, that is, the information recording portion, only the cantilever 2 is in contact with the information recording portion, and the cantilever 3 is in non-contact with the recording medium. When approaching the convex portion 7, the distance control cantilever 3 comes into contact with the slope 11 of the convex portion, and the contact continues for a distance of 100 nm in the horizontal direction before passing through the convex portion 7. At this time, if a voltage is applied between the distance control cantilever 3 and the electrode layer 4 by the power supply 12, the energization current 13 is detected and the contact time is measured as 10 ms from the energization time. It is shown that the distance 10 from the cantilever tip to the medium was accurate at 50 nm. If the contact time is longer than 10 ms, it means that the head-medium distance is shorter than the set value. Therefore, the actuator 14 is contracted to recover the distance. Similarly, if the contact time is less than 10 ms, the actuator 14 is extended to recover the distance. This operation is repeated at intervals of 1 μm in which the convex portions 7 are arranged to keep the distance between the head media constant. Since the recording / reproducing cantilever 2 is longer than the distance control cantilever 3 by 2 μm, it is in contact with the recording medium in the recording area. Can fulfill. Since the head 1 raster-scans the surface of the medium in the X direction, the stripes of the convex portions 7 on the medium are aligned in the Y direction orthogonal to the raster scanning. As described above, the convex portion 7 is a region for controlling the distance, and the region applicable to recording is a flat region other than the convex portion on the medium surface.

The cantilever 3 for controlling the distance has a spring constant of 10 N / m in order to reduce the influence on the contact detection due to the attraction force to the surface of the recording medium acting on the tip portion, and also reliably energizes. Therefore, the applied voltage is 6V.

By controlling the distance between the head and the medium as described above, the recording / reproducing cantilever 2 can be brought into contact with the medium with a constant load for scanning, and recording / reproducing by energizing from the tip of the cantilever. You can At this time, the mounting angle of the cantilever 2 with respect to the recording medium is 30 degrees, the deflection amount is about 1 μm, and the load amount by the cantilever 2 is about 100 nN by setting the spring constant of the cantilever at 0.1 N / m. .

The recording medium selected in this embodiment is recorded at a recording voltage of 3.5 V or higher. Using this, for example, to record a mark row with a recording mark diameter of 30 nm and a recording interval of 100 nm, 4 V is applied to the recording / reproducing cantilever,
A recording pulse of 1 ms may be applied at a cycle of 10 ms, and this head may be scanned at 10 μm / s. Further, in the reproduction, the voltage applied to the recording / reproducing head is kept constant at 2V, which is lower than 3.5V, and the flowing current is detected, whereby the reproduction can be performed.

In the embodiment of FIG. 2, the head and the recording medium have been described as moving relatively in the X and Y directions. However, the magnetic recording is currently performed and the head is stopped. It will be clear that it could be similar to the device. In this case, when the head 1 is located near the rotation center axis and when it is located near the outer circumference, the heads pass through the projections if the widths of the projections are the same even if the distance between the head media is the same. Since the time will change, it is necessary to change the width of the convex portion or the judgment level.

[0019]

According to the present invention, a cantilever is provided in the head portion, a convex portion is provided on the surface of the recording medium, and the contact time between the cantilever and the convex portion is measured to detect the distance between the head recording mediums. Control. By doing so, a complicated distance detection mechanism can be omitted, the head can be made simple and lightweight, and it contributes to high-speed and high-precision control of the head.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a basic configuration of a head of a recording / reproducing apparatus according to an embodiment.

FIG. 2 is a diagram showing an example of the configuration of a recording medium to which the present invention can be applied, in the form of a perspective view with a cross section.

FIG. 3 is a graph for controlling the distance between head media to be constant.
The conceptual diagram explaining the mechanism of distance control.

[Explanation of symbols]

1: head, 2: recording / reproducing cantilever, 3: distance control cantilever, 4: Pt layer, 5: substrate, 6: glass substrate, 7: convex portion, 8: electrode layer, 9: recording layer,
a: distance from the tip of the cantilever to the recording medium, 11: slope of the convex portion, 12: power supply, 13: energizing current, 14: actuator,

Claims (3)

[Claims] 1. An information recording / reproducing apparatus having a recording medium and a recording / reproducing head arranged facing the recording medium, wherein a convex portion is provided on a part of the surface of the recording medium, and the head portion can contact the convex portion. A cantilever, and the head-to-recording-medium distance is controlled to be substantially constant by controlling the height position of the head with respect to the recording-medium surface so that the contact time with the convex portion of the cantilever becomes substantially constant. An information recording / reproducing apparatus characterized by the above. 2. The information recording / reproducing apparatus according to claim 1, wherein the detection of the contact time of the cantilever with the convex portion is performed by detecting energization between the cantilever and the convex portion. 3. An information recording / reproducing apparatus having a recording medium and a recording / reproducing head arranged facing the recording medium, wherein a convex portion is provided on a part of the surface of the recording medium, and the head portion can contact the convex portion. A cantilever, and the head-to-recording-medium distance is controlled to be substantially constant by controlling the height position of the head with respect to the recording-medium surface so that the contact time with the convex portion of the cantilever becomes substantially constant. In addition, the head portion is provided with a second cantilever,
An information recording / reproducing apparatus, wherein information is recorded in an area other than the area of the convex portion by the second cantilever.