JPH1064059A - Projection detecting method and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely detect all over projection on a magnetic recording medium by transferring respective sliders in the direction of juxtaposing and detecting projections with respective projection detecting sensors. SOLUTION: A magnetic disk 1 is set on a rotating disk 112. The rotation of a spindle motor 111 of the rotating disk 112 is controlled by a rotation controller 113. A transferring stage 121 is controlled by a stage controller 126 so that the projection detecting sensor 128 mounted on an inner circumferential slider 125 positions in the inner circumferential edge of the disk 1. The stage 121 is transferred in the outer circumferential direction with the controller 126. A projection detecting signal is inputted into a signal comparing circuit 132 via a signal amplifying circuit 131 and compared with the magnitude of slice level from a slice level signal storage circuit 133. When the projection detecting signal is larger than the slice level signal or more, disk radius positional information is recorded on the recording medium 141 or the like and displayed in a displaying device 142 with a data output circuit 134.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for detecting protrusions on a magnetic recording medium on which information such as data and programs are recorded and reproduced by magnetism.

[0002]

2. Description of the Related Art As a magnetic recording medium, there is, for example, a magnetic disk or a magnetic tape. Examples of a device that records information on a magnetic disk and reproduces the information recorded on the magnetic disk include a hard disk device and a flexible disk device. Magnetic films are formed on both surfaces of the magnetic disk built into the hard disk drive, and information is track-shaped on the magnetic film by a magnetic head mounted on a head slider floating above the surface of the magnetic disk. Information recorded and recorded in a track shape on the magnetic film is reproduced.

Since the magnetic films formed on both surfaces of the magnetic disk are formed by sputtering or the like, projections may be formed on the surface of the magnetic film immediately after the film formation. These projections may adversely affect the recording and reproduction of information by the magnetic head mounted on the head slider, so it is necessary to remove the projections. Therefore, a head slider on which a waffle head having a file function is mounted is arranged on the surface of the magnetic disk, and the waffle head is moved in the radial direction of the magnetic disk while rotating the magnetic disk to cut off the protrusion. .

After the removal of the protrusions is completed, FIG.
As shown in FIG. 0, a slider 2 on which a protrusion detection sensor is mounted is arranged on the surface of the magnetic disk 1, and the slider 2 can be moved in the radial direction of the magnetic disk 1 while rotating the magnetic disk 1 to remove the slider. The presence or absence of the missing protrusion is detected by the protrusion detection sensor, and the magnetic disk 1 is inspected.

[0005] A piezoelectric element is used in a conventional projection detection sensor. The protrusion is detected by causing the slider 2 on which the protrusion detection sensor is mounted to fly above the magnetic disk 1 with an arbitrary flying height, and the vibration generated when the slider 2 collides with a protrusion higher than the flying height. The protrusion is detected by the piezoelectric element, and the protrusion is detected by the output voltage from the piezoelectric element according to the degree of the collision. The vibration of the slider 2 at this time does not occur due to the loss of the flying stability of the slider 2 due to the protrusion, but in most cases is the natural vibration generated due to the impact applied to the slider 2. Therefore, the vibration frequency of the voltage observed from the piezoelectric element is also the natural frequency of the slider 2.

However, the above-described method for detecting a projection by the projection detection sensor using a piezoelectric element has the following disadvantages. That is, the next protrusion cannot be detected until the vibration of the slider 2 at the time of the collision of the protrusion is settled. However, since the settling time is long, the protrusion appearing during the settling cannot be detected. . Furthermore, since the detection sensitivity of the piezoelectric element is limited, it is not possible to detect minute projections, which are problematic.

Further, when inspecting a magnetic disk radially divided into a data recording area and a control signal recording area by an uneven portion formed on the surface, a non-projection may be detected as a projection. It is. That is, when the slider 2 flies over the magnetic disk on which the irregularities are formed, the flying height of the slider 2 fluctuates when the slider 2 moves from the data recording area to the control signal recording area. When the fluctuation of the flying height occurs, the slider 2 vibrates by receiving acceleration from the magnetic disk, so that the piezoelectric element outputs a voltage and is detected as a protrusion.

Therefore, a method of detecting a protrusion by a protrusion detection sensor using a resistor instead of the piezoelectric element is considered.
The projection detection sensor using the resistor uses the energy that is converted into heat, out of the energy obtained by the resistor when the resistor and the projection collide. That is, since the energy converted into heat raises the temperature of the resistor to increase the resistance of the resistor, the protrusion can be detected by detecting a change in the resistance value of the resistor.

[0009]

In the above-described method for detecting a projection by the projection detection sensor using a piezoelectric element, even if the projection collides with a portion other than the piezoelectric element, the slider 2 resonates and its vibration is reduced. , A projection detection signal is generated. Accordingly, even if the piezoelectric element 3 is mounted near one side of the rear end face of the slider 2 as shown in FIG. Is determined by the width of

On the other hand, in the method of detecting a projection by a projection detection sensor using a resistor, a projection detection signal is not generated even when the projection collides with the slider 2, and the projection detection signal is generated only when the projection collides with the resistor. Occurs. Accordingly, as shown in FIG. 11B, when the resistor 4 is mounted near one side of the rear end face of the slider 2 as shown in FIG. 4 is determined.

Here, the flying range of the slider 2 on the magnetic disk 1 is defined by the fact that the inner peripheral side surface of the slider 2 contacts the inner peripheral edge defining the information recording area of the magnetic disk 1, and the outer peripheral side surface of the slider 2 Is in contact with the outer peripheral edge defining the information recording area of the magnetic disk 1. In the case of the protrusion detection sensor using the piezoelectric element 3, the protrusion can be detected over the entire information recording area of the magnetic disk 1 regardless of where the piezoelectric element 3 is disposed on the slider 2 for the above reason.

However, in the case of the protrusion detection sensor using the resistor 4, for example, when the resistor 4 is disposed at the center of the slider 2, the slider 2 is positioned at a position closer to the inner periphery of the magnetic disk 1 to define the information recording area. The resistor can only pass over the area from the position shifted to the outer peripheral side by half the width of the slider 2 to the position shifted from the outer peripheral edge defining the information recording area of the magnetic disk 1 to the inner peripheral side by half the width of the slider 2. Therefore, for the above reason, it is impossible to detect the protrusion over the entire information recording area of the magnetic disk 1.

For example, when the resistor 4 is disposed on one side of the slider 2, the resistor 4 is shifted from the inner periphery defining the information recording area of the magnetic disk 1 to the outer periphery by the width of the slider 2. The width of the slider 2 from the outer edge defining the information recording area of the magnetic disk 1 on the area up to the outer edge defining the information recording area of the magnetic disk 1 or from the inner edge defining the information recording area of the magnetic disk 1 Since the resistor 4 can pass only over the area shifted to the inner peripheral side by the distance, the protrusion cannot be similarly detected over the entire information recording area of the magnetic disk 1.

In such a case, if the slider 2 is moved beyond the flying range, protrusions can be detected over the entire information recording area of the magnetic disk 1. However, the slider 2 may crash without flying. There is a problem that the detection of the projection itself becomes impossible.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a projection detecting method and apparatus capable of accurately detecting the projections on a magnetic recording medium over the entire surface.

[0016]

According to the present invention, there is provided a method for detecting a protrusion on a magnetic recording medium on which information is recorded / reproduced by magnetism. This is achieved by mounting a projection detection sensor on each of the sliders, arranging the sliders side by side, moving the sliders in the alignment direction, and detecting the projections by the projection detection sensors.

According to the above configuration, the protrusions are detected by the plurality of protrusion detection sensors arranged in parallel.
There is no projection undetectable area, and projections on the magnetic recording medium can be accurately detected over the entire surface.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. The embodiments described below are preferred specific examples of the present invention, and therefore, various technically preferable limitations are added. However, the scope of the present invention is not limited to the following description. It is not limited to these forms unless otherwise stated.

FIG. 1 is a block diagram showing an embodiment of a projection detecting device according to the present invention. The projection detecting device 100 detects the projection of the magnetic disk 1 mounted on the rotating unit 110 by the projection detecting unit 120, processes the signals from the rotating unit 110 and the projection detecting unit 120 by the signal processing circuit 130, and Output. Rotating part 110
Is the rotary disk 1 connected to the spindle motor 111
The magnetic disk 1 is mounted and fixed on the magnetic disk 12 and rotated under the control of the rotation controller 113.

The protrusion detecting section 120 includes two suspensions 122 and 123 mounted on a moving stage 121 disposed near the rotating section 110 and each suspension 1.
Sliders 124, 1 attached to
The slider 25 is moved in the radial direction of the magnetic disk 1 under the control of the stage controller 126, and the sliders 124, 1
The protrusions on the magnetic disk 1 are detected by the protrusion detection sensors 127 and 128 mounted on the magnetic disk 1.

The signal processing circuit 130 includes the protrusion detection sensor 1
The protrusion detection signal from the signal amplification circuit 131
, And the slice level signal stored in advance in the slice level signal storage circuit 133 is input to the signal comparison circuit 132 and compared with the protrusion detection signal. Then, the comparison result from the signal comparison circuit 132 is input to the data output circuit 134, and the disk angle information input from the rotation controller 113 and the disk radius position information input from the stage controller 124 are written to the recording medium 141 or the like according to the comparison result. It is output and displayed on the display device 142.

One end of each of the two suspensions 122 and 123 is arranged in parallel in the radial direction of the magnetic disk 1 and is fixed to the moving stage 121, and the other end has sliders 124 and 1
25 is fixed. Then, as shown in FIG. 2, the slider 124 disposed on the outer peripheral side of the magnetic disk 1
The protrusion detection sensor 127 is mounted near the outer peripheral side of the rear end face of the slider 125, and the protrusion detection sensor 127 is mounted near the inner peripheral side of the rear end face of the slider 125 disposed on the inner peripheral side of the magnetic disk 1.
8 is mounted.

An example of an arrangement for detecting protrusions over the entire information recording area of the magnetic disk 1 using the protrusion detection device 100 will be described with reference to FIGS. Magnetic disk 1
The distance from the center of the protrusion detection sensors 127 and 128 in the radial direction to the center of the sliders 124 and 125 is s, the distance between the centers of the sliders 124 and 125 is d, and the inner peripheral edge defining the information recording area of the magnetic disk 1 If the distance from the edge to the outer peripheral edge is 1 and the projection detection sensors 127 and 128 are arranged so as to satisfy the relationship of d = 1 / 2-2s, the projection can be detected over the entire information recording area of the magnetic disk 1. Can be.

That is, a half area on the inner circumference side from the inner circumference to the outer circumference defining the information recording area of the magnetic disk 1 can be inspected by the protrusion detection sensor 128,
The half area on the outer peripheral side can be inspected by the protrusion detection sensor 127. The moving distance of the moving stage 121 at this time may be l / 2, and the inspection by the protrusion detection sensors 127 and 128 is performed simultaneously during one l / 2 movement. Therefore, the information recording area of the magnetic disk 1 can be inspected over the entire surface, and the inspection time can be reduced to almost half of the conventional case.

Here, the protrusion detection sensors 127 and 128
Are, as shown in FIG. 4, lead wires 127a, 128a,
A resistor 127 having 127b and 128b connected to both ends
c, 128c. Resistors 127c, 12
8c has a thermal conductivity of 60 W / mK to 80 W
/ MK, permalloy with a resistance value of 27Ω and specific heat of 0.13
For example, tantalum having 9 J / gK, a density of 16.6 g / cm3, and a temperature sensitivity of 0.1% / ° C can be used. Copper can be used as a material for the lead wires 127a, 128a, 127b, and 128b. The slider 12
As the sliders 4 and 125, those having the size of a general nano-slider can be used.
As the suspensions 122 and 123 for applying a load to the vehicle, so-called type 19 suspensions can be used.

Such projection detecting sensors 127 and 128
First, permalloy is formed on the rear end surfaces of the sliders 124 and 125 by vapor deposition or tantalum by sputtering. Next, the permalloy film or the tantalum film is etched by a dry etching method to form resistors 127c and 128c. Then, lead wires 127a, 128a, 127b, 128b are formed of copper at both ends of the permalloy film or the tantalum film to form projection detection sensors 127, 128.

The protrusion detection sensors 127 and 128 use the energy converted into heat from the energy obtained by the resistors 127c and 128c when the resistors 127c and 128c collide with the protrusions on the magnetic disk 1. It is. That is, the energy converted into heat is converted into the resistance 127
Since the resistance is increased by increasing the temperature of c and 128c, the protrusion can be detected by detecting the change in the resistance value of the resistors 127c and 128c.

The resistors 127c and 128c are formed of a thin film.
Since the heat capacities of c and 128c are small, even if the energy is small at the time of colliding with the minute projection, the resistors 127c and 128c may be used.
The change in the resistance value of c increases, and the resistance of the resistor 127 increases.
Since the thermal diffusivity of c and 128c increases, the protrusion detection time, that is, the time from when the resistors 127c and 128c collide with the protrusion to when the resistors 127c and 128c settle becomes shorter.

The resistors 127c and 128c are exposed on the surfaces of the sliders 124 and 125. By doing so, no energy is generated when the resistors 127c and 128c collide with the projections. Since heat is directly converted by the resistors 127c and 128c themselves without any intervention, the detection sensitivity of the protrusion detection sensors 127 and 128 can be enhanced to detect even minute protrusions. still,
Lead wires 127 are provided at both ends of the resistors 127c and 128c.
a, 128a, 127b, 128b are connected, so that the lead wires 127a, 128a, 127b, 12
8b is connected to a constant current source to supply a constant current to the resistors 127c and 1c.
28c, the resistors 127c, 128
A change in the resistance value of c can be detected as a change in voltage.

Such a protrusion detection sensor 127 (12
The detection of a projection on a general magnetic disk 1 having a flat surface according to 8) will be described. The magnetic disk 1 used was
This is a bump disk in which cylindrical bumps having a diameter of 30 μm and a height of 40 nm are linearly arranged radially at respective positions of a radius of 20 mm, 24 mm and 28 mm of the magnetic disk 1. The slider 124 (125) is arranged at each bump position, and the slider 124 (125) is changed by changing the relative speed between the slider 124 (125) and the bump disk.
The flying height of 5) was changed. That is, the slider 124 (1
The flying height of the slider 124 (125) increases as the relative speed between the bump disk 25) and the bump disk increases.

FIG. 5 shows the protrusion detection sensor 127 (128).
FIG. 9 is a diagram showing a relationship between the output voltage of the slider 124 and the flying height of the slider 124 (125). The output voltage of the protrusion detection sensor 127 (128) is, as is apparent from FIG.
4 (125) becomes smaller when the flying height is larger than the height of the bump, and becomes extremely large when the flying height of the slider 124 (125) is smaller than the height of the bump. As shown in FIG. 6A, the waveform of the output voltage of the protrusion detection sensor 127 (128) is
When the flying height of 5) is larger than the height of the bump, a downwardly convex waveform is formed, and as shown in FIG.
When the flying height of No. 4 (125) is smaller than the height of the bump, an upwardly convex waveform is obtained. This is for the following reason.

When the flying height of the slider 124 (125) is larger than the height of the bump, the resistor 127c (128)
Although c) does not collide with the bump, the resistor 127c (128)
When c) passes over the bump, the resistor 127c (12
The distance between 8c) and the bump disk surface is reduced by the height of the bump. Thereby, the resistor 127c (128
c) the thermal resistance between the bump disk and
This is because the heat of the resistor 127c (128c) is released to the bump disk side, and the resistance of the resistor 127c (128c) decreases. Therefore, the output voltage of the resistor 127c (128c) through which the constant current flows becomes small.

If the flying height of the slider 124 (125) is smaller than the height of the bump, the resistor 127c
(128c) collides with the bump, and the resistor 127c (12
This is because heat is generated in 8c) and the resistance value of the resistor 127c (128c) increases. Therefore, the output voltage of the resistor 127c (128c) through which the constant current flows increases. When the flying height of the slider 124 (125) is substantially the same as the height of the bump, it is considered that the effect of heat dissipation when approaching the bump and the effect of heat absorption when colliding with the bump are mixed. As described above, by using the resistor 127c (128c), it is possible to detect a projection on a general magnetic disk having a flat surface.

Next, the above-described protrusion detection sensor 127 (1
The detection of the protrusion on the magnetic disk having the unevenness on the surface according to the method 28) will be described. The magnetic disk used has an uneven portion (a black portion in FIG. 7B is a convex portion) as shown in a plan view showing the entire shape of FIG. 7A and a plan view showing a partial shape of the surface in FIG. The magnetic disk 11 has a data recording area (data zone) and a control signal recording area (servo zone) which are formed radially.

The servo zone has an arc shape from the inner circumference to the outer circumference of the magnetic disk 11 corresponding to the skew angle of the magnetic head.
m. In the data zone, a concentric data track for recording data or the like is formed so as to have a track pitch of 4.8 μm and a track width of 3.8 μm. Slider 12
4 (125) is disposed on the magnetic disk 11 at a protrusion of 100 nm in height, and the slider 124 (125) is
m.

FIG. 8 shows the projection detection sensor 127 at this time.
It is a figure showing the waveform of the output voltage of (128). Small waveforms appearing at both ends of the figure are the protrusion detection sensors 127 (12
8) The waveform of the output voltage at the time of passing through the servo zone of FIG.
7 shows a waveform of an output voltage at the time of a projection collision on the magnetic disk 11 of FIG. 7 (128). Thus, the protrusion detection sensor 127
The magnitude of the output voltage of (128) is different between when passing through the servo zone and when colliding with the projection, and is larger when colliding with the projection than when passing through the servo zone. Also, the protrusion detection sensor 127
The waveform of the output voltage of (128) is different between when passing through the servo zone and when projecting. From the above, the resistor 127c (1
By using the method 28c), it is possible to detect a protrusion on the magnetic disk 11 having an uneven portion on the surface.

Here, the protrusion detection sensor 127 (128)
The reason why the voltage is output even when the servo zone passes through will be described. The gap between the resistor 127c (128c) and the magnetic disk 11 is equal to the flying height of the sliders 124 and 125,
nm. Considering the dimension of the resistor 127c (128c) and the dimension of the gap, it is considered that the resistor 127c (128c) always emits heat onto the magnetic disk 11 through the gap.

In the servo zone and the data zone, the ratio of the concave and convex portions on the surface of the magnetic disk 11 under the sliders 124 and 125 is different. This means that the resistor 127c (128c)
This indicates that the thermal resistance of the magnetic disk 11 differs from that of the magnetic disk 11. Generally, the ratio of the uneven portions is larger in the data zone. Therefore, the data zone has lower thermal resistance. Thus, the protrusion detection sensor 127 (128)
Is passed through the servo zone, the resistor 127c (1
The resistance value of 28c) is slightly increased, and a voltage is output.

The rise in the resistance value of the resistor 127c (128c) when the protrusion detection sensor 127 (128) passes through the servo zone depends on the resistance of the resistor 127c (128c) when the protrusion detection sensor 127 (128) collides with the protrusion. Very small compared to the rise in resistance. This is because the resistor 127c (12
The surface 8c) facing the magnetic disk 11 is the surface of the ultra-thin film resistor in the thickness direction. Considering that the thickness of the resistor 127c (128c) is on the order of nanometers, the output voltage of the difference in thermal resistance due to the difference in the ratio of the concave and convex portions is the output voltage of the protrusion detection sensor 127 (128) when the protrusion collides. Obviously, it is smaller than.

Therefore, the protrusion detection sensor 127 (128)
Output voltage when passing through the servo zone and the protrusion detection sensor 1
By providing a slice level between the projection voltage and the output voltage at the time of collision of the protrusion 27 (128), the protrusion detection sensor 127 is provided.
It is possible to determine only the output voltage at the time of the projection collision of (128). Therefore, by setting the slice level to be equal to or higher than the output voltage of the projection detection sensor 127 (128) when passing through the servo zone and equal to or lower than the output voltage of the projection detection sensor 127 (128) when colliding with the projection, the resistor 127c is set.
An output can be obtained only when (128c) collides with a protrusion on the magnetic disk 11.

The output voltage of the protrusion detection sensor 127 (128) when passing through the servo zone and the output voltage of the protrusion detection sensor
Since the output voltage of the projection detection sensor 127 (128) is determined only by the output voltage of the projection detection sensor 127 (128) at the time of the projection collision, since the output voltage of the projection detection sensor 127 (128) is different from the output voltage of the projection detection sensor 127 (128). It is possible to do.

An example of the operation of the above-described protrusion detection device 100 will be described with reference to the flowchart of FIG. First, the magnetic disk 1
Is set on the turntable 112 (step STP1).
The rotation controller 113 controls the rotation of the spindle motor 111 so that the turntable 112 rotates at a predetermined rotation speed (step STP2). Stage controller 1
Reference numeral 26 denotes a moving stage 121 so that, for example, a protrusion detection sensor 128 mounted on an inner slider 125 is located at an inner periphery defining an information recording area of the magnetic disk 1.
Is controlled (step STP3).

When the protrusion detection sensor 128 is located at the inner periphery defining the information recording area of the magnetic disk 1 (step S
TP4) The stage controller 126 controls the moving stage 121 to move at a predetermined speed in the outer peripheral direction (step STP5). The signal amplifying circuit 131 receives the protrusion detection signals from the protrusion detection sensors 127 and 128, amplifies the signals, and outputs the amplified signals to the signal comparison circuit 132. Upon receiving the projection detection signal from the signal amplification circuit 131, the signal comparison circuit 132 reads the slice level signal from the slice level signal storage circuit 133 and compares the magnitude of the projection detection signal with the slice level signal (step STP6).

When the protrusion detection signal is smaller than the slice level signal, the signal comparing circuit 132 returns to step STP5 and repeats the above-described operation. When the protrusion detection signal is equal to or larger than the slice level signal, the signal comparison circuit 132 outputs the protrusion detection signal to the data output. Output to the circuit 134. Then, the data output circuit 1
Reference numeral 34 denotes the disk angle information input from the rotation controller 113 and the disk radius position information of the protrusion detection sensors 127 and 128 input from the stage controller 126 corresponding to the protrusion detection signal input from the signal comparison circuit 132, and the recording medium 141 or the like. And display device 1
42 is displayed (step STP7).

Then, the stage controller 126
It is checked whether or not the protrusion detection sensor 127 mounted on the outer peripheral side slider 124 is positioned at the outer peripheral edge defining the information recording area of the magnetic disk 1 (step STP8). If it is not located at the outer peripheral edge defining the information recording area yet, step S
Returning to TP5, the above operation is repeated. On the other hand, when the protrusion detection sensor 127 is located at the outer peripheral edge defining the information recording area of the magnetic disk 1, the inspection processing ends.

The arrangement of the protrusion detection sensors and the like in the above embodiment is not limited, and may be any arrangement as long as it can inspect the entire information recording area of the magnetic disk. Also, the case where two sliders are arranged in parallel has been described, but three or more sliders may be arranged in parallel, and the inspection time can be shortened accordingly.
Further, a moving stage may be provided for each slider, and the movement may be controlled for each slider.

[0047]

As described above, according to the present invention,
Since the protrusions on the magnetic recording medium can be accurately detected over the entire surface, the accuracy of information recording and reproduction can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a protrusion detection device of the present invention.

FIG. 2 is a perspective view showing a detailed example of a main part of the protrusion detection device shown in FIG.

FIG. 3 is a plan view showing an example of arrangement of main parts of the protrusion detection device shown in FIG. 1;

FIG. 4 is a perspective view showing a detailed example of a protrusion detection sensor used in the protrusion detection device shown in FIG.

FIG. 5 is a diagram showing a relationship between an output voltage of a protrusion detection sensor shown in FIG. 4 and a flying height of a head slider.

6 is a diagram showing a waveform of an output voltage of the protrusion detection sensor shown in FIG.

FIG. 7 is a plan view showing the overall shape of the magnetic disk and a plan view showing a partial shape of the surface of the magnetic disk.

8 is a diagram showing a waveform of an output voltage of the protrusion detection sensor shown in FIG.

FIG. 9 is a flowchart illustrating an embodiment of a protrusion detection method according to the present invention.

FIG. 10 is a perspective view for explaining a conventional projection detection method.

FIG. 11 is a diagram showing sensor sensitivity depending on a difference in a projection detection sensor used in a conventional projection detection method.

[Explanation of symbols]

Reference numerals 1, 11: magnetic disk, 100: protrusion detecting device, 110: rotating unit, 111: spindle motor, 112: rotating disk, 113: rotation controller, 120: protrusion Detector, 121: moving stage, 122, 123: suspension, 124, 1
25: slider, 126: stage controller, 127, 128 ... protrusion detection sensor, 127a,
128a, 127b, 128b ... lead wire, 127
c, 128c: resistor, 130: signal processing circuit, 131: signal amplification circuit, 132: signal comparison circuit, 133: slice level signal storage circuit, 13
4 Data output circuit 141 Recording medium 14
2 Display device

Claims (7)

[Claims] 1. A method for detecting protrusions on a magnetic recording medium on which information is recorded / reproduced by magnetism, wherein a protrusion detection sensor is mounted on at least two sliders floating on the magnetic recording medium, respectively. A projection detecting method, wherein the sliders are moved in the direction in which the sliders are arranged, and the projections are detected by the respective projection detection sensors. 2. The projection detection method according to claim 1, wherein the projection detection sensor comprises a resistor that detects a change in temperature due to energy obtained when the projection collides with the projection. 3. When two sliders are arranged side by side, the protrusion detection sensor is mounted near one side of the one slider in the direction of movement, and near the side of the other slider on the side of the other movement. The projection detection method according to claim 1, wherein the projection detection sensor is mounted on the projection. 4. The projection detection method according to claim 1, wherein the movement of each of the sliders is simultaneous. 5. An apparatus for detecting a protrusion on a magnetic recording medium on which information is recorded / reproduced by magnetism, comprising:
Sliders, a protrusion detection sensor mounted on each of the sliders, a moving unit for simultaneously moving the sliders in the juxtaposed direction, and a signal processing circuit for processing a signal from the protrusion detection sensor. A projection detection device characterized by the above-mentioned. 6. The projection detection device according to claim 5, wherein the projection detection sensor is a resistor that detects a change in temperature due to energy obtained when the projection collides with the projection. 7. When two sliders are provided side by side, the protrusion detection sensor is mounted near a side surface of one of the sliders on the side of one movement direction, and near a side surface of the other slider on the side of the other movement direction. The projection detection device according to claim 5, wherein the projection detection sensor is mounted on the projection detection device.