JP2002150526A - Magnetic recording medium and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium which eliminates a dropout by effectively removing the projections on the front surface of the magnetic recording medium and eliminates a seizure, etc., of a magnetic head by adequately maintaining the polishing ability of the magnetic recording medium with respect to the surface of the magnetic head and a method of manufacturing the same. SOLUTION: The magnetic recording medium 1 has a central region 2 set at the width of a value of any of the range of 70% to 85% of the central part of a recording width where recording and reproducing of data by the magnetic head are carried out and side end regions 3a and 3b on the both right and left side across the central region 2. The central region 2 and the side end regions 3a and 3b vary in surface roughness. The stock removal of the side end regions 3a and 3b is so set as to be made 2 to 20 times as compared with the stock removal per unit time of the magnetic head by polishing of the central region 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for recording or reproducing various data such as video and music in a recording / reproducing apparatus having a metal magnetic head such as a VTR (video tape recorder). And a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in manufacturing a magnetic recording medium of this type, a magnetic powder or a binder is applied on a base, and the surface of the magnetic recording medium is smoothed using an abrasive such as a polishing tape. That is being done. By performing such a smoothing process, unnecessary protrusions and the like that protrude from the surface of the magnetic recording medium with a nonstandard size can be removed, and the occurrence of dropout can be eliminated.

In general, when the polishing ability of the magnetic recording medium on the surface of the magnetic head is low, burn-in or the like occurs on the metal-based magnetic head, so it is necessary to secure an appropriate polishing ability on the surface of the magnetic recording medium. is there. For this reason, an abrasive is mixed in the magnetic recording medium in order to appropriately polish the surface of the magnetic head.

However, when the surface of the magnetic recording medium is smoothed as described above, even the projections of the abrasive particles are polished, and the polishing ability on the surface of the magnetic head is practically insufficient. In some cases. In order to avoid the abrasion of the protrusions due to such abrasive particles, the surface smoothing treatment of the magnetic recording medium may be weakened. However, if the treatment is excessively weakened, unnecessary protrusions and the like are sufficiently effective. And the dropout during reproduction cannot be reduced.

[0005]

As described above, in the case of a magnetic recording medium such as a magnetic tape, it is necessary to apply a smoothing treatment to the surface of the magnetic recording medium in order to remove a projection which causes a dropout during reproduction. However, due to the smoothing process, there is a problem that the polishing ability of the magnetic recording medium on the surface of the magnetic head is reduced, and burn-in or the like occurs on the magnetic head. However, on the other hand, if the smoothing process on the surface of the magnetic recording medium is excessively weakened or the smoothing process itself is omitted, there is a problem that it is impossible to reduce or eliminate dropout during reproduction.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object to effectively remove protrusions on the surface of a magnetic recording medium to eliminate dropouts and to reduce the magnetic force applied to the surface of a magnetic head. It is an object of the present invention to provide a magnetic recording medium and a method of manufacturing the same, which can maintain the polishing ability of the recording medium properly and can eliminate burn-in of the magnetic head and the like.

[0007]

SUMMARY OF THE INVENTION A magnetic recording medium according to the present invention is set so that recording or reproduction is performed while moving and contacting a metal-based magnetic head. A plurality of regions are distributed in the width direction (a direction orthogonal to the moving direction of the magnetic recording medium), and at least two of the plurality of regions have different surface roughnesses from each other, and are units for the magnetic head due to friction. The polishing amount per hour (the head polishing amount) is different. Here, the metal-based magnetic head means, of course, a magnetic head using various metal materials such as a ferrite-based, FeAlSi-based, and FeCoSiB-based.

In the method of manufacturing a magnetic recording medium according to the present invention, a plurality of regions are provided in a width direction (a direction orthogonal to a moving direction) of the magnetic recording medium, and at least two regions among the plurality of regions are provided. The method includes a smoothing step of making the surface roughness different from each other so that the polishing amount per unit time for the magnetic head is different.

In the magnetic recording medium according to the present invention, for example,
As the plurality of areas described above, the recording width of the central portion in the width direction is 7
At least three regions, that is, a central region set to any value of 0% or more and less than 85% of the recording medium width, and two side end regions sandwiching the central region are arranged so that a total of three regions are distributed. The polishing amount per unit time of the magnetic head due to the friction in the center region is set to 2 to 20 times the polishing amount per unit time of the head due to the friction in the central region, so that the polishing ability on the surface of the magnetic head can be properly maintained. ,
Burn-in of the magnetic head is also suppressed.

In the magnetic recording medium according to the present invention, for example,
The surface of the magnetic recording medium is partially polished in the width direction with respect to the surface of the magnetic recording medium, for example, by using an abrasive material that is set so as to contact the surface of the magnetic recording medium in an arc shape with a predetermined radius of curvature. By bringing the materials into contact, a plurality of regions having different surface roughnesses in the width direction are distributed, and the polishing amount per unit time with respect to the magnetic head differs in those regions.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a schematic configuration of a cross section in a width direction of a magnetic recording medium according to an embodiment of the present invention, and FIG. 4 shows a positional relationship between the magnetic recording medium and a magnetic head.

The magnetic recording medium 1 is, for example, a magnetic tape, and has a width of 70% of a recording width for recording / reproducing data in a width direction (a direction orthogonal to a running direction of the tape).
A central region 2 having a width of any value in the range of 85% to 85%, and side end regions 3a and 3b on both left and right sides sandwiching the central region 2 are provided. In the present embodiment, by distributing a plurality of regions having different surface roughnesses from each other, the magnetic head 100
The polishing amount of the side end regions 3a and 3b is set to be any magnification within the range of 2 to 20 times, for example, 6 times as compared with the polishing amount per unit time (hereinafter, referred to as head polishing amount). Is set.

If this ratio is less than twice, even if the width of the central area 2 is set to 70% or more of the recording width for recording / reproducing data as described above, the central area 2 and the side edge area It is no longer possible to obtain a practically significant difference in the amount of head polishing between 3a and 3b, and if the ratio exceeds 20 times, the friction with the magnetic recording medium 1 causes the magnetic head 1
As compared with the vicinity of the area related to recording / reproducing of No. 00, the other area wears out earlier, causing significant uneven wear in the width direction of the magnetic head 100 and shortening its life. For this reason, the ratio of the polishing amount per unit time between the central region 2 and the side end regions 3a and 3b, in other words, the specific wear rate of the magnetic head 100 due to friction with the magnetic recording medium 1 is reduced by the central region. It is desirable to set the distribution of the surface roughness in the width direction of the magnetic recording medium 1 so as to fall within the range of 2 to 20 in the case of 2 and in the case of the side end regions 3a and 3b.

Since the friction phenomenon between the surface of the magnetic recording medium 1 and the surface of the magnetic head 100 on which the fine particles of the abrasive (not shown) protrude, is basically abrasive friction.
When the magnetic heads 100 are the same, it can be considered that a linear correlation is approximately established between the wear rate and the surface roughness. Based on this, the surface roughness of the side end regions 3a and 3b of the magnetic recording medium 1 is set to be 2
By setting to 20 times, the ratio of the polishing amount of the magnetic head 100 by the side end regions 3a and 3b to the polishing amount of the magnetic head 100 by the central region 2 can be set to 2 to 20. Alternatively, a more detailed correlation between the wear rate and the surface roughness is obtained in advance by an experiment or the like, and based on the correlation, each of the side end regions 3a and 3b of the magnetic recording medium 1 and the central region 2 is determined. The target set value of the surface roughness may be set more precisely.

In this embodiment, when the magnetic head 100 is mounted on a recording / reproducing apparatus under normal conditions, the average wear rate in the width direction of the magnetic head 100 is 1.0 per 100 [h (hour)]. The surface roughness of the portion of the magnetic recording medium 1 that is in contact with the magnetic head 100 is set so as to be 5 [μm] or less. This means that the average wear rate in the width direction of the magnetic head 100 is 1.5 μm per 100 h.
m], the life of the magnetic head 100 as a whole is shortened, and a practical usable time cannot be secured. Here, more desirably, by setting the average wear rate in the width direction of the magnetic head 100 to 0.4 [μm] or more per 100 [h], a practical polishing ability can be more reliably secured.

Next, a method for manufacturing the above-described magnetic recording medium 1 will be described with reference to FIGS. 2 and 3A and 3B.
The description focuses on the smoothing process. FIG. 2 shows an outline of an apparatus for performing the smoothing process.

First, the magnetic recording medium (magnetic tape) 1 which has been processed into a predetermined width (slit processing) and wound around the supply-side guide roll 5 is mounted on a smoothing processing device. At this time, the leading end of the magnetic recording medium 1 is mounted so as to be wound up from the supply side guide roll 5 through the contact roll 7 to the winding side guide roll 6.

From this state, the magnetic recording medium 1 is wound from the supply side guide roll 5 to the winding side guide roll 6 at a predetermined feed speed. A contact roll 7 is arranged in the middle of the winding path, and a polishing tape 8 is inserted between the surface of the contact roll 7 and the magnetic recording medium 1. As shown in FIG. 3A, a tensile force is applied to the polishing tape 8 in the running direction of the magnetic recording medium 1 at a predetermined holding angle θ as shown in FIG. As shown in B), it is mounted with a pressing force applied at a predetermined radius of curvature r. Here, the reason why the curvature radius r is provided is to prevent scratches and the like since the frictional force with respect to the magnetic recording medium at both ends of the polishing tape becomes excessively strong at the time of processing if the surface is flat. The polishing tape 8 is transferred from the roll 9 to the roll 10 by, for example, 5 [m
/ Min], and is set so as to always maintain a state in which a predetermined polishing ability can be obtained at a portion that comes into contact with the surface of the magnetic recording medium 1.

The surface of the magnetic recording medium 1 has a polishing tape 8
The central region 2 that is in contact with the surface is partially smoothed to remove unnecessary protrusions and the like, while the smoothing process is mostly performed in the side edge regions 3a and 3b on both sides thereof. Without being affected, the non-smooth treated surface provided with the roughness due to the fine particle projections of the abrasive compounded in advance is maintained.

At this time, the distribution of the central region 2 and the side end regions 3a and 3b in the width direction of the magnetic recording medium 1 and the magnetic head 1 assumed after completion of the magnetic recording medium 1
The positional relationship with 00 is, for example, as shown in FIG. In the case illustrated here, the magnetic head 10
0 and the center area 2 of the magnetic recording medium 1
Are set to be substantially the same, but the width of the central region 2 is 70% of the width of the recording region 101 of the magnetic head 100.
It is desirable to set the value to any value within the range from above to less than 85% of the recording medium width.

The polishing amount per unit time of the magnetic recording medium 1 in this smoothing process is determined by the polishing tape 8
, The contact pressure and the contact area between the polishing tape 8 and the magnetic recording medium 1, the feed speed of the magnetic recording medium 1, the feed speed of the polishing tape 8, and the like can be adjusted as appropriate. It is. Accordingly, the above values are appropriately adjusted, and the ratio of the polishing amount per unit time to the magnetic head 100 in the central region 2 and the side end regions 3a and 3b in the magnetic recording medium 1 obtained by performing the smoothing process. Should be within the range of 2 to 20, and the average value of the polishing amount in the width direction should be within 1.5 [μm] per 100 [h].

The distribution of the center region 2 and the side end regions 3a and 3b in the width direction of the magnetic recording medium 1 is determined by the combination of the width of the magnetic recording medium 1 and the width and the curvature r of the contact roll 7, and the distribution of the contact roll 7 It can be adjusted by changing the installation position or the like.

It is needless to say that the distribution of the surface roughness of the magnetic recording medium 1 is not limited to the division into the central region 2 and the side edge regions 3a and 3b on both sides as shown in FIG. No. In addition, for example, the magnetic recording medium 1
The width direction of the magnetic head 10 is further divided into a number of regions.
It is also possible to provide a larger number of regions where the polishing amount per unit time with respect to 0 is large and a region where the amount is small.

Example A magnetic recording medium was manufactured by performing the above-mentioned smoothing treatment on the surface, and various characteristics of the magnetic recording medium were evaluated.

As a polishing tape, GC-3 containing chromium oxide or the like as a polishing agent manufactured by Nihon Micro Coating Co., Ltd. is used.
000 (model number), a magnetic recording medium coated with a magnetic layer or the like is mounted on a smoothing processing apparatus as shown in FIG. m
m]) Video tapes for the beta cam format from Sony were produced. In addition, as a polishing tape used for this surface treatment, in addition to one using chromium oxide as an abrasive, for example, WA-400 using alumina is used.
0 (model number) and those using titanium oxide as an abrasive are applicable. The roughness is 1000-
A number of 10,000 is preferred. For example, PET (polychlorinated terephthalate) or the like is used as the base material. As the binder, nitrocellulose, cellulose acetyl butyrate, vinyl chloride, polyurethane, polyamide, polyester and the like are used.

More specifically, the feed speed of the magnetic recording medium 1 is 500 [m / min], the feed speed of the polishing tape 8 is 50 [mm / min], the diameter of the contact roll 7 is 30 [mm], The angle θ is set to 120 [degrees], the contact pressure between the polishing tape 8 and the magnetic recording medium 1 is adjusted by controlling the tensile force before and after the contact roll 7, and the surface of the magnetic recording medium 1 is smoothed. went.

As a comparative example, using a flat contact roll 700 as shown in FIG. 6, the polishing tape 800 is brought into contact with the magnetic recording medium 11 with a substantially uniform contact pressure over the entire surface in the width direction. Two examples of the conventional magnetic recording medium obtained by performing the processing and one example in which the smoothing processing was not performed at all were prepared. At this time, in order to match the polishing treatment capacity of the polishing tape with that of the above embodiment, the tensile force of the polishing tape was adjusted so that the contact pressure per unit width became the same as that of the above embodiment.

For each of the magnetic recording media 1 of the present embodiment and the comparative example, a beta cam VTR / BVW-7 made by Sony of the NTSC system was actually used as a recording / reproducing apparatus.
5, a dropout occurrence state and S / S when a test pattern signal for evaluation is recorded and reproduced.
The N deterioration amount was evaluated. At this time, recording is performed using a signal of 50% white as a test pattern, and S is measured by the measurement at the time of initial running by reproduction and the measurement after running 100 passes of 20 minutes length.
/ N degradation amount was measured. The measurement environment at this time is 20
[° C.]. 20 [%] RH.

As a headwear characteristic in each case, recording and reproduction for 30 minutes per volume were reduced to 100 volumes by using an NTSC system Sony Betacam VTR / BVW-70 as a recording / reproduction device. The average value of the wear amount of the video head composed of four ferrite heads (the polished amount of the video head due to the friction with the magnetic recording medium) after the test was performed was evaluated. The measurement environment at this time is 20
[° C.] · 60 [%] RH.

As the target set value, the average of the dropout is 6 to 8 [pieces / min] (10 [μs] / − 10).
[DB]), and the amount of headwear is set to 0.1 per 100 [h].
4 to 1.0 [μm], and the S / N deterioration amount is 0 to -4 [dB].
And The various characteristics obtained by this evaluation experiment are summarized as shown in FIG.

That is, in the case of the prior art 2 in which the highest priority is given to adapting the dropout to the target set value, the dropout could certainly be 6.8 [pieces / min]. , The head wear amount of the magnetic recording medium becomes 0.3 [μm] lower than the target set value range of 0.4 to 1.0 [μm], the S / N deterioration amount becomes -6, and The range greatly deviated from 0 to -4 [dB], and the S / N ratio was significantly deteriorated.

Further, in the case of the prior art 1 in which the top priority is given to adapting the head wear amount and the S / N deterioration amount of the magnetic recording medium to the target set value, the head wear amount becomes 0.6 and the S / N deterioration amount becomes 0.6. Although the amount was a good value of −2 [dB],
On the other hand, dropout averaged 12.4 [pieces / mi
n], and an average of target set values of 6 to 8 [pieces / mi]
n] by about twice. In addition, in the case of Conventional Example 3, the average value of dropout was 4.7, which was a good value, but the S / N deterioration amount was -8 [dB].

Further, when no smoothing processing is performed, the headwear amount becomes extremely large at 1.8 [μm], and the S / N deterioration amount is set to the minimum of −1 [dB]. Yes, but on the other hand, dropout is 20.
8 [pieces / min] occurred remarkably, resulting in a large deviation from the target set value of 6 to 8 [pieces / min] on average.

However, using the smoothing method according to the present invention as described in the above embodiment, the smoothing process is performed only on the central region 2 extending about 8 mm at the center in the width direction. In the case of the magnetic recording medium (the first and second embodiments) in which the side edge regions 3a and 3b on both sides are left unprocessed, the result is that all target set values can be satisfied. It became. That is, in the case of the first embodiment shown in FIG.
m], the S / N deterioration amount was -2 [dB], and the average dropout was 7.0 [pieces / min]. At this time, the surface roughness of the treated tape was 1550. In the case of the second embodiment, the headwear is 0.3 [μm], the S / N deterioration amount is -6 [dB], and the average dropout is 4.9 [pieces / min]. Was. At this time, the surface roughness of the treated tape was 1500.

According to such a comparative evaluation experiment, according to the manufacturing method of the present embodiment and the magnetic recording medium 1 manufactured by the above, the protrusions on the surface of the magnetic recording medium 1 can be effectively removed. It has been proved that dropout at the time of recording / reproducing can be eliminated, and that the amount of headwear, that is, the polishing ability of the magnetic recording medium 1 on the surface of the magnetic head 100 can be properly maintained to prevent burning of the magnetic head. Was.

[0037]

As described above, claims 1 to 3 are described.
According to the method for manufacturing a magnetic recording medium according to any one of claims 1 to 4, or the method for manufacturing a magnetic recording medium according to any one of claims 4 to 8, a plurality of regions having different surface roughnesses are arranged in the width direction of the magnetic recording medium. By distributing such that the polishing amount per unit time (head polishing amount) for the head due to friction with the magnetic recording medium is different in each area, unnecessary protrusions on the surface of the magnetic recording medium are eliminated. It can be effectively removed to eliminate dropouts,
There is an effect that it is possible to appropriately maintain the polishing ability of the magnetic recording medium on the surface of the magnetic head and to eliminate seizure of the magnetic head.

According to the method for manufacturing a magnetic recording medium of the present invention, the polishing amount per unit time averaging the entire area is 1.5 μm per 100 hours.
Since the setting is made as follows, it is possible to prevent the wear rate of the magnetic head due to friction with the surface of the magnetic recording medium from exceeding a practically effective range.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating a schematic configuration of a cross section in a width direction of a magnetic recording medium according to an embodiment of the present invention.

FIG. 2 is a diagram showing an outline of an apparatus for performing a smoothing process on the surface of the magnetic recording medium shown in FIG.

FIG. 3 is a diagram showing a contact state between a polishing tape and a magnetic recording medium on the surface of a contact roll, and FIG.
Is a view along the running direction of the magnetic recording medium, and FIG.
It is the figure which followed the AA arrow cross section of (A).

FIG. 4 is a diagram showing a distribution of a center region and a side end region in a width direction in a magnetic recording medium and a positional relationship with respect to a magnetic head at the time of recording / reproducing of the magnetic recording medium.

FIG. 5 is a diagram collectively showing various characteristics obtained by an evaluation experiment.

FIG. 6 is a diagram showing, as a comparative example, a conventional smoothing method in which a polishing tape is brought into contact with a magnetic recording medium at a substantially uniform contact pressure over the entire width direction.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Magnetic recording medium, 2 ... Central area, 3a, 3b ... Side edge area, 5 ... Supply side guide roll, 6 ... Winding side guide roll, 7 ... Contact roll, 8 ... Polishing tape.

Claims (7)

[Claims] 1. A magnetic recording medium which is set so that recording or reproduction is performed while making contact with a metal-based magnetic head while moving relative to the magnetic head, and a width direction orthogonal to the moving direction. A plurality of regions are distributed, at least two of the plurality of regions are regions having different surface roughnesses, and they have different polishing amounts per unit time with respect to the magnetic head due to friction. Magnetic recording medium. 2. A central region set to any value within a range of 70% or more to less than 85% of a recording width at a central portion in a width direction of the magnetic recording medium as the plurality of regions, and a central region thereof. And at least three regions are distributed between the two side end regions, and the polishing amount per unit time with respect to the magnetic head due to friction in the side end regions is the unit time with respect to the head due to friction in the central region. 2. The magnetic recording medium according to claim 1, wherein the surface roughness of the side edge region and the surface roughness of the central region are made different from each other so as to be 2 to 20 times the polishing amount per unit. 3. The polishing amount per unit time of the magnetic head per unit time averaged over the plurality of regions is 1.5 μm or less per 100 hours.
The magnetic recording medium according to the above. 4. A method for manufacturing a magnetic recording medium in which recording or reproduction is performed while making contact with a metal-based magnetic head while moving relative to the metal-based magnetic head, the method comprising: Recording medium such that at least two of the plurality of regions have different surface roughnesses, and the amount of polishing of the magnetic head per unit time due to friction with them is different. A method of manufacturing a magnetic recording medium, comprising: 5. The smoothing step includes: bringing a polishing material into partial contact with the surface of the magnetic recording medium in a width direction so as to reduce the surface roughness of the contacted region to a non-contacted region. 5. The method for manufacturing a magnetic recording medium according to claim 4, wherein the method is different. 6. The flattening step includes setting the plurality of regions to have a recording width of 70% at a central portion in a width direction of the magnetic recording medium.
% And at least three regions, that is, a central region set to any value within a range of not less than 85% and less than 85%, and two side end regions sandwiching the central region. So that the polishing amount per unit time of the head due to the friction of the head is 2 to 20 times the polishing amount per unit time of the head due to the friction in the central region.
5. The method for manufacturing a magnetic recording medium according to claim 4, wherein the surfaces of the side edge region and the central region are polished. 7. The smoothing step includes: polishing a surface of the magnetic recording medium such that a polishing amount per unit time of the magnetic head averaged over the plurality of regions per unit time is 1.5 μm or less per 100 hours. 5. The method according to claim 4, wherein the magnetic recording medium is subjected to a smoothing process.