JPH0227565A - Pad device for magnetic head - Google Patents

Abstract

PURPOSE:To always realize the stable travel of a recording medium by forming notched parts at the upstream side and the downstream side parts of a magnetic head. CONSTITUTION:The notched parts 16-19 with the same width dimension as that of a head embedding hole 15 are formed in partial areas at the upstream side and downstream side in the traveling direction of the recording medium 1 on the medium sliding plane 12 of a first block part and the medium sliding plane 14 of a second block part inside and outside a groove part 13. The depth of the notched parts 16 and 17 at the upstream side are formed shallowly and that of the notched parts 18 and 19 at the downstream side deeply. Therefore, the rise of static pressure generated at the downstream side according to the travel of the recording medium 1 slidably with a pad device 11 can be reduced by the notched parts 16 and 17. Furthermore, even when the pad device 11 is inclined slightly against the recording medium 1, the abnormal rise of negative pressure due to the inclination can be reduced by the notched parts 18 and 19. In such a way, it is possible to keep the attractive force of the recording medium 1 constant, and to stabilize the travel of the recording medium 1.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a pad device for a magnetic head, more specifically,
The present invention relates to a magnetic head pad device for stably running a magnetic recording medium in a magnetic recording/reproducing device or the like.

[Prior Art] In a recording and reproducing apparatus for recording and reproducing information on a recording medium such as a magnetic disk, a pad device is usually used to bring the recording medium into stable contact with a magnetic head. This conventional pad device generally forms a space around the magnetic head, and is provided around the space to face the recording medium together with the magnetic head (for example, in Japanese Patent Application Laid-Open No.
(See Publication No. 9-54071). The function of a pad device with this type of structure is that when the recording medium runs, the air in the space is dragged by the recording medium and flows out, and the amount of air that flows into the space is smaller. This generates negative pressure in the space, and the running recording medium is attracted to the pad device and brought into close contact with the magnetic head.

Therefore, the shape and operation of the above-mentioned conventional general pad device will be explained with reference to the drawings.

In the pad device 81 shown in FIGS. 8(A) and 8(B), on the surface facing the recording medium 1, a first block portion in which a head embedding hole 15 in which a magnetic head 2 is disposed at a central position protrudes. An annular groove 13 is formed around this protruding medium sliding surface 12, and a medium sliding surface 14 of an annular second block portion protruding toward the recording medium 1 is formed outside the groove 13. It will be done. Regarding each dimension of the pad device 81, the inner diameter φ of the groove portion 13 is 3. 5+aw+, its outer diameter φ2 is 6mm, the outer diameter φ3 of the medium sliding surface 14 of the second block part is 7mm, and the depth of the groove 13 is 50jm.
+ The medium sliding contact surface 1 of this pad device 81
4 and the recording medium 1 is maintained at 11.

Here, when the recording medium 1 is run in the direction shown by the arrow X with respect to the pad device 81, as described above, a flow is generated in the air between the pad device 81 and the recording medium 1. Pressure will be generated. Therefore, a fluid dynamic simulation was performed to examine the pressure distribution on the facing surface of the pad device 81 and the recording medium 1, as shown in FIG. 9. In the characteristic diagram of FIG. 9, the horizontal axis represents the pad device 8 shown in FIG. 8 (13) above.
Corresponding to the position of each point Pl-P8 on the center line of 1,
The vertical axis represents the relative pressure with respect to the recording medium 1.

[Problems to be Solved by the Invention] As is clear from FIG.
In the area upstream in the running direction from the medium sliding contact surface 12 of the block part (region of points P1 to P6), the air pressure is negative and positive, which is lower than atmospheric pressure. and the medium sliding contact surface 14 of the second block part
The pressure is positive in the area (area of points P6 to P8).

For this reason, the pad device 81 and the recording medium 1 are not stably attracted to each other in the downstream region, and the running of the medium 1 becomes unstable. Actual measurement data also reveals that in the downstream region where the pressure is positive, the recording medium 1 vibrates, causing so-called fluttering, and is significantly deviated from stable running.

The reason why the positive pressure is generated is considered to be that the airflow becomes stagnant on the downstream side of the groove portion 13, and the pressure in the downstream region increases as a result.

Note that the medium sliding contact surface 1 of the first block portion of the pad device 81
A head embedding hole 15 is provided in the center of the head embedding hole 15, and the magnetic head 2 is embedded in the embedding hole 15, but the amount of protrusion of the magnetic head 2 is small, and in this simulation,
The amount of protrusion of the magnetic head 2 is not particularly considered.

The same applies to the embodiments and other pad devices described later.

In this way, in the conventional pad device, it is true that the running of the recording medium becomes unstable on the downstream side in the running direction.
This is revealed by the data. Therefore, in a recording/reproducing apparatus having such a pad device, it is difficult to obtain a stable contact state between the magnetic head and the recording medium.

Furthermore, experiments have revealed that conventional pad devices sometimes abnormally adsorb recording media, which impedes the running of the media. The reason for this is thought to be that, as will be described later, when the pad device is tilted relative to the recording medium, the negative pressure increases rapidly. If the recording medium is sucked abnormally to the extent that it interferes with its running, stable signal recording and reproduction will no longer be possible. Further, a large load is placed on the drive motor that rotates the recording medium, making it difficult to downsize this motor and save power consumption.

The present invention was made in view of these problems, and
It is an object of the present invention to provide a pad device for a magnetic head that constantly stabilizes the running of a recording medium.

[Means for Solving the Problems] The magnetic head pad device of the present invention includes a first block portion around the magnetic head, and a protruding medium sliding surface of the first block portion faces the recording medium. A second block portion is provided on the outer peripheral side of the first block portion. The second block part is
The first block portion is located so as to surround at least the upstream side of the magnetic head with respect to the running of the recording medium, and has a medium sliding contact surface that protrudes on the side facing the recording medium. A first notch is formed in the second block part on the downstream side of the magnetic head with respect to the travel of the recording medium, as if the second block part was cut out from the side of the medium sliding contact surface. Further, in one or both of the first block part and the second block part, on the upstream side of the magnetic head with respect to the traveling of the recording medium, one or both of the block parts is arranged from the medium sliding surface. A second notch is formed as if it were cut out.

[Function] As the recording medium runs in sliding contact with the pad device, the increase in static pressure that occurs downstream of the magnetic head with respect to the running of the recording medium is reduced by the first notch. . Furthermore, even if the pad device is arbitrarily tilted with respect to the recording medium, the second notch reduces abnormal increases in negative pressure, so the suction force of the recording medium becomes constant, and the running of the recording medium becomes stable. do.

[Example] Figure 1 (A) shows the shape of an example of the pad device of the present invention.
, shown in ([)). This pad device 11 basically has substantially the same shape as the pad device 81, and its dimensions are also similar, but on the medium sliding contact surface 12 of the first block portion inside and outside the groove portion 13, On the medium sliding contact surface 14 of the second block part, the head is placed in a partial area on the upstream side and downstream side in the running direction of the recording medium 1 when viewed from the position of the head embedding hole 15 where the magnetic head 2 is disposed. This differs from the pad device 81 in that notches 16, 17, 18, and 19 are formed with the same width as the embedded hole 15.

The depth of the notches 16 and 17 on the upstream side is shallow, and the depth of the notches 18 and 19 on the downstream side is deep.

Here, as in the case described above, a hydrodynamic simulation is performed and the pad device i! When the relative pressure distribution between 211 and the recording medium 1 is examined, it is as shown in FIG. In FIG. 2, the characteristic line f11 indicates the notch 16,
17 is set to 10j11, and the depth of the cutouts 18 and 19 is set to 20#l, the characteristic line g2 corresponds to the cutout 1.
6 and 17 have the same depth <10x11, and the above notch 1
When the depth of the notches 8 and 19 is 30 μm, the characteristic line 13 corresponds to the case where the depth of the notches 18 and 19 is 501 m.

As is clear from FIG. 2, the cutout portions 16 and 17
And when the notches 18 and 19 exist, in the entire area of the surface of the pad device 11 facing the recording medium 1,
The air pressure between the recording medium 1 and the recording medium 1 is negative and positive. Even if the depth of the downstream notch 18.19 is changed, points P3~
Although the level of P6 changes slightly uniformly, the pad device 11
There is no change in the fact that negative pressure is generated in the entire area of the surface facing the recording medium 1 . The profile of the relative pressure distribution is that from point P to P2, the pressure suddenly goes from 0 level (atmospheric pressure) to negative and positive, maintains an approximately constant negative pressure level from points P2 to P6, and from point P6 to P8, the relative pressure becomes negative. The pressure has increased to O level.

Further, when the depth of the upstream notches 16 and 17 is 20g11 and the depth of the downstream notches 18 and 19 is 50I11, that is, the upstream notch of the pad device corresponding to the characteristic line g3 Examining the case where the depths 16 and 17 are increased, the negative pressure level decreases, but the profile is almost the same as the characteristic line g3.

In this way, in the pad device 81, points P6 to
By forming the notches 16 to 19 like the pad device 11 described above, the relative pressure between P8 and P8 is changed to point P including the points P6 to P.
All areas from 1 to P8: Negative pressure at 8. The reason for this is believed to be that the airflow on the downstream side of the groove portion 13 escapes to the outside of the pad device 11 through the cutout portion 19, thereby preventing a rise in pressure in this downstream region. For comparison, the pad device 101 shown in FIGS. 10(A) and (13) and the pad device 101 shown in FIGS. 11(A) and (13)
This is clear from FIG. 12 obtained from the simulation results of the pad device 111 shown in FIG.

The pad device 101 is not provided with the upstream cutout portions 16 and 17 with respect to the pad device 11 of the present invention,
The pad device 111 is designed so that the notch 18 on the second block further downstream is not provided. That is, the pad device 101 has a notch 18. on the downstream side of the first block portion. A notch 19 is provided on the downstream side of the second block portion, and the pad device 111 is provided with the notch portion 19 only on the downstream side of the second block portion. Characteristic line g4 in FIG. 12 corresponds to pad equipment ff101, and characteristic line 1
5 corresponds to the pad device 111.

In the simulation, the notch 18 of the pad device 101
．． 19 and the depth of the notch 19 of the pad device 111 are both 50#l. This characteristic line N4. N
5, these pad devices 101,1
Regarding pad device 11, the profile is slightly different compared to the pad device 11, but the point P t ""' P
It can be seen that the pressure is negative in the entire range of g.

Therefore, essentially, it can be seen that simply providing the notch 19 on the downstream side of the second block can prevent the pressure from increasing between points P6 to P8, and the relative pressure will not become positive.

However, the above is a case where the medium sliding contact surface of the rosette device is arranged parallel to the recording medium 1 with a -like space maintained therebetween. In reality, it is difficult to achieve a completely parallel arrangement due to distortion of the recording medium 1 itself or alignment accuracy of the pad device.

Therefore, as shown in FIG. 13, for each of the pad devices 101 and 111, the medium sliding contact surface is positioned at an angle θ to the downstream side in the running direction of the recording medium 1.
Figures 14 and 15 show the results of a study on the case where the robot is tilted by .

As is clear from FIGS. 14 and 15, if the inclination angle θ of the pad device 101, 111 is made very large,
If the distance from the recording medium 1 becomes too large, pressure fluctuations from atmospheric pressure will disappear, but if the tilt angle θ is minute, the negative pressure will fluctuate greatly. Characteristic line j! in Figure 14! ,, fI7°18 is the inclination angle θ of the pad device 101
respectively 0.005°, 0.01°, 0.02@
In this case, the characteristic line '9''10'' 1 in Figure 15
1 similarly sets the inclination angle θ of the pad device 111 to 0.
．． 005", 0.01@0.02@. These characteristic lines are defined as the characteristic line N4. shown in FIG.
As is clear from the comparison with N5, pad=i101.1
11, it can be seen that by slightly tilting the medium sliding contact surface, the negative pressure can be greatly increased. The reason for this is that the downstream notch 18°19
This is thought to be due to the fact that the air is separated from the recording medium 1, and its function as an escape route for airflow is strengthened. Even so, the pad device 101 having the notch 18 in the first block portion has a smaller rate of negative pressure fluctuation than the pad device 111. When actually performing a recording/reproducing experiment using the pad device 101° 111, the recording medium 1 may sometimes be abnormally adsorbed, causing trouble in the running of the recording medium 1. However, the above simulation results This is considered to support this experimental fact.

On the other hand, to explain the case where the pad device 11 of this embodiment is similarly tilted, the characteristic line '12''1 shown in FIG.
3''' 14 is the first
Similarly to the pad devices 101 and 111 shown in FIG.
, 0.01°, 0.02" □. As can be seen by comparing these characteristic lines g1°, Ω13" 14 with the characteristic line g1 when the pad device 11 is not tilted. Even when the pad device 11 is tilted, almost no negative pressure fluctuation is observed.

Naturally, there is no change in the fact that negative pressure is generated over the entire area from points P1 to P8. Therefore, by providing the notches 16 and 17 on the upstream side, even if the pad device 11 is tilted, the notches 16 and 17 effectively act as an escape route for the air flow, preventing the relative pressure from rising R1. It is thought that this can be done.

Next, the shape of each modification of the pad device of the present invention is shown in FIGS. 4-6.

The pad device 41 shown in FIG. 4 is formed by forming a cutout portion 19A which is an enlarged version of the cutout portion 19 on the downstream side of the second block portion in the pad device 11. The depth of the notches 16 and 17 on the upstream side is 10 μm, and the notch 1 on the downstream side
The case where the depth of 8.19A is 30 pm is shown in FIG. 7 as characteristic line '15.

Further, the pad device 51 shown in FIG. 5 and the pad device 61 shown in FIG. 6 are provided with only one of the notches 16 and 17 on the upstream side of the pad device 11. The pad device 51 has only the notch 16 on the upstream side, and the pad device f&61 has only the notch 17. The respective pressure distributions for the pad devices 51.61 are shown in FIG. , point P
Negative pressure is generated over the entire range from 1 to P8, and its profile is also relatively flat.

Further, the results when the inclination angle θ of the pad devices 41, 51, and 61 are set to 0-02° are shown in FIG. 7 as characteristic lines 1.1) and fJ', respectively.

When the pad device is tilted with respect to the recording medium 1, in the pad device 51, 61, negative pressure fluctuation occurs locally in the upstream region where the notch is not provided, but in the region where the notch is provided. , negative pressure fluctuations are suppressed, and this is a change compared to the pad device 101 or 111. Pad equipment VX14
1, the negative pressure hardly changes even if it is tilted.

As described above, the pad device of the present invention has a notch in at least the second block portion on the downstream side of the magnetic head 2, and a notch in either or both of the first block portion and the second block portion on the upstream side. By having a negative pressure in the entire area, even if the pad device is tilted with respect to the recording medium 1, the negative pressure characteristic profile does not change significantly.

Note that the pad device of the present invention is not limited to the shape shown in FIG. 1 and FIGS. 4 to 6;
The width and depth of each of the notches 7, 18, and 19 may be changed, and furthermore, the media sliding contact surface of the first block part, the groove part, and the second
The medium sliding contact surface of the block portion does not have to be formed concentrically, and may be formed into an ellipse or a shape including a straight portion.

[Effects of the Invention] As described above, according to the present invention, by forming simple notches in the upstream and downstream parts of the magnetic head with respect to the running of the recording medium, static pressure in the downstream area can be reduced. Further, even if the pad device is slightly tilted with respect to the recording medium, an abnormal increase in negative pressure can be prevented and stable running of the recording medium can be realized at all times.

[Brief explanation of the drawing]

1(A) and (B) are a longitudinal sectional view and a plan view of the medium facing surface of a pad device showing an embodiment of the present invention, and FIG. 2 is a plan view of the pad device shown in FIGS. Figure 3 is a characteristic diagram showing the pressure distribution when using the pad device shown in Figure 1 (A) and (B) above, when the pad device shown in Figures 1 (A) and (B) is tilted toward the recording medium. FIGS. 4, 5 and 6 are, respectively, a plan view of the medium facing surface of a pad device showing other embodiments of the present invention, and FIG. is a characteristic diagram showing the pressure distribution when using each of the pad devices shown in FIGS. 4 to 6 above, and FIGS. A vertical cross-sectional view and a plan view of its medium facing surface, FIG. 9 are a characteristic diagram showing the pressure distribution when the pad device shown in FIGS. 8(A) and (13) are used, and FIG. 10 is (A) and (B) are a longitudinal cross-sectional view of an example of a pad device shown for comparison and a plan view of its medium facing surface; FIGS. 11 (^) and (B) are shown for comparison A vertical cross-sectional view of another example of the pad device and a plan view of its medium facing surface, and FIG. 12 is a characteristic diagram showing the pressure distribution when each of the pad devices shown in FIG. 10.11 above is used. It is. FIG. 13 is a side view showing the pad device tilted with respect to the recording medium, and FIG. 14 is the pressure distribution when the pad device shown in FIG. 10 is tilted gently with respect to the recording medium. FIG. 15 is a characteristic diagram showing the pressure distribution when the pad device shown in FIG. 11 is slightly tilted with respect to the recording medium. 1... Recording medium 2... Magnetic head 11.41, 51.61... Pad device 12.
...Medium sliding contact surface 13 of the first block portion...
・Groove portion 14...Medium sliding contact surface 16 of second block portion...
...Notch on the upstream side of the second block part (second notch) 17... Notch on the upstream side of the first block part (second notch) 18... Notch 19 on the downstream side of the first block part
．． 19A...Notch part on the downstream side of the second block part (first notch part)

Claims (1)

[Claims] (1) A first block portion disposed around the magnetic head and having a medium sliding contact surface protruding toward the side facing the recording medium; and a first block portion disposed on the outer peripheral side of the first block portion; a second block portion that is located so as to surround at least an upstream side of the magnetic head with respect to the running of the recording medium and has a medium sliding contact surface that protrudes toward the side facing the recording medium; and the magnetic head of the second block portion. a first notch portion formed as if the second block portion was cut out from the medium sliding surface side, on the downstream side with respect to the traveling of the recording medium; and the first block portion and/or the second block portion. a second notch formed by cutting out the first block part and/or the second block part from the medium sliding surface side, upstream of the magnetic head with respect to the running of the recording medium; A magnetic head pad device comprising: