Stock material or miscellaneous articles – Structurally defined web or sheet
Reexamination Certificate
2002-03-25
2003-09-16
Resan, Stevan A. (Department: 1773)
Stock material or miscellaneous articles
Structurally defined web or sheet
C428S141000, C428S216000, C428S690000, C360S134000
Reexamination Certificate
active
06620483
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to magnetic recording media advantageously employed in the recording of computer data. More specifically, the present invention relates to a magnetic recording medium advantageously employed in magnetic recording and reproduction systems employing magnetoresistive reproduction heads (MR heads).
BACKGROUND OF THE INVENTION
Systems incorporating thin-film magnetic heads have been developed in recent years in magnetic recording and reproduction systems for the recording and reproduction of computer data. Since thin-film magnetic heads are small and readily processed into multitrack heads, multitrack fixed heads in the form of thin-film magnetic heads are widely used, particularly in systems employing magnetic tapes as the recording medium.
Thin-film magnetic heads afford improved recording efficiency and increased track density due to their small size, permitting both high-density recording and improved data transmission rates through the use of multitracks.
Thin-film magnetic heads can be roughly divided into the categories of inductive heads, which respond to changes in magnetic flux over time, and magnetoresistive heads (MR heads), which exploit magnetoresistive effects in responding to changes in magnetic flux magnitude. Due to their flat structure, inductive heads have a low number of head coil windings and do not permit the use of large magnetomotive forces. Accordingly, they have a drawback in that adequate reproduction output cannot be achieved. Thus, MR heads, which readily yield high reproduction outputs, are employed in reproduction, while inductive heads are used for recording.
These recording and reproduction heads are normally built into systems in integrated (combined) form. Linear recording systems affording comparatively rapid data transmission are employed in such magnetic recording systems.
The magnetic tape for computer data recording employed in magnetic recording and reproduction systems into which MR heads are incorporated is determined for each system. For example, known are magnetic tapes corresponding to Models 3480, 3490, and 3570 based on IBM specifications.
These magnetic tapes are of a basic configuration in which a single-layer-structure magnetic layer of a comparatively substantial thickness of about 2.0 to 3.0 &mgr;m comprising ferromagnetic powder and binder is provided on a support. Normally, in such data recording magnetic tapes, a backcoat layer is provided on the back surface on the opposite side from the magnetic layer to prevent winding irregularity and ensure good running durability.
However, such magnetic recording tapes of single-layer structure are problematic in that they are unable to adequately respond to the demands recently placed on them as a storage medium for large quantities of data. In response to such problems, a magnetic recording tape employed in magnetic recording systems incorporating thin-film magnetic heads has been disclosed (Japanese Unexamined Patent Publication (KOKAI) Heisei No. 8-227517), for example. This medium is a magnetic recording medium (magnetic recording tape) in which a lower nonmagnetic layer comprising an inorganic nonmagnetic powder dispersed in binder is provided on a nonmagnetic support and a thin upper magnetic layer in which a ferromagnetic metal powder is dispersed in binder is provided over the nonmagnetic layer.
By employing a thin magnetic layer as the upper layer in this magnetic recording tape, drop in output due to thickness loss is prevented. Further, since high recording densities can be achieved, a higher data storage capacity can be achieved than in the above-described magnetic recording tapes having a single-layer-structure magnetic layer. Specifically, an embodiment is described in the form of a magnetic recording tape for recording computer data in which, on one side of a polyethylene terephthalate support 10 &mgr;m in thickness, a nonmagnetic layer 2.7 &mgr;m in thickness and a magnetic layer 0.3 &mgr;m in thickness are sequentially provided.
To achieve high-recording densities and high capacity, the tracks in magnetic recording systems for data storage are becoming progressively narrower. In the case of magnetic tapes, in longitudinal (linear) recording systems, recording and reproduction heads are driven in the width direction and a track must be selected. That is, during recording and reproduction, the magnetic head must be moved in the width direction (vertical direction) of the magnetic recording tape to select any tracks. However, the narrower the track width, the greater the precision required to control the relative positions of the magnetic recording tape and head.
In conventional methods, the running position of the tape is fixed with a guide or the like and the head moves up and down in a predetermined position. However, if the track width becomes narrow, when the tape expands and contracts within the system, or when the run position of the tape is displaced from the anticipated position, the reproduction head is displaced from the optimal position on the recorded track and output drops. Accordingly, it is necessary to record a servo signal in advance in the longitudinal direction and determine the position of the head relative to the tape to achieve high recording densities.
Information recording by magnetic recording and servo control signal controls such as a positional signal are both performed in the same magnetic layer in conventional magnetic recording tapes. Further, due to the surface properties of the magnetic recording tape, controls are conducted by recording servo control signals on the same surface as the smooth information recording layer. Thus, the capacity of information that can be recorded is that much lower and it is impossible to adequately respond to recent needs for high density and high capacity. The same performance is not required of the magnetic layer for recording servo signals as the magnetic layer for recording information signals. In some cases, there are different performance requirements than for the magnetic layer for recording information signals.
For example, the medium described in Japanese Unexamined Patent Publication (KOKAI) Heisei No. 4-248120 is a magnetic recording medium employing a servo-type magnetic disk for data recording. To stably maintain the servo signal, this medium has a layered structure in which a first magnetic layer, a nonmagnetic layer, and a second magnetic layer are provided on a nonmagnetic support in this order, the coercivity of the lower magnetic layer recording the servo signal is set to equal to or higher than 159 kA/m (2,000 Oe), and the coercivity of the upper magnetic layer for recording information signals is set to equal to or higher than 95.5 kA/m (1,200 Oe). However, when a magnetic recording medium of such a configuration is employed as a magnetic tape for recording and reproducing in the longitudinal direction in a linear recording system, satisfactory results are not necessarily achieved. That is, because of the high coercivity of the lower magnetic layer, there is a problem in that a substantial load is placed on the head, precluding accurate reading of the servo signal and substantially increasing output variation and the like, thus rendering servo signal control difficult.
However, since high recording density and high recording capacity are required as set forth above, there is a need to impart a higher Hc to the magnetic layer that is used to record information signals. Additionally, high recording density is not required of the magnetic layer for the recording of the servo signals to the same degree that it is required in recording information.
Accordingly, Japanese Unexamined Patent Publication (KOKAI) No. 2000-315312 discloses a magnetic tape configured with magnetic layers on both sides, one of the magnetic layers of which is an information recording magnetic layer used exclusively to record information signals and the other magnetic layer of which is a servo signal recording magnetic layer used exclusively to record servo c
Kasuga Akira
Sueki Minoru
Fuji Photo Film Co. , Ltd.
Resan Stevan A.
LandOfFree
Magnetic recording medium does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Magnetic recording medium, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetic recording medium will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3002705