Dynamic magnetic information storage or retrieval – Record copying – Contact transfer
Reexamination Certificate
2001-10-23
2004-08-24
Hudspeth, David (Department: 2651)
Dynamic magnetic information storage or retrieval
Record copying
Contact transfer
C360S016000
Reexamination Certificate
active
06781777
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a master information carrier which is used when an information signal such as of preformat information is initially recorded to an information recording medium and also which has such a region, on the surface of a base member, in which a pattern corresponding to such an information signal is formed that is higher in level than the other regions. More particularly, the present invention relates to a technology for eliminating such damages and improper uniform adhesion of the information medium due to sticking/residing of foreign matter at the time of transfer-wise recording of the information signal to the information recording medium.
2. Description of the Related Art
A master information carrier is used to transfer and record a preformat information signal to a magnetic recording medium. The preformat information signals include a tracking servo signal, an address information signal, a reproduction clock signal and the like. Such a signal is recorded at a constant angle pitch in each track of a disk which is the magnetic recording medium. In the master information carrier, a shape pattern made of a ferromagnetic thin film corresponding to an information signal on the surface of the base member is formed. The master information carrier is adhered to the magnetic recording medium to transfer and record the shape pattern corresponding to the information signal in the master information carrier on the magnetic recording medium as an information signal by an action of magnetization.
To make sure of adhesion, the base member of the master information carrier is sectioned into a high-level region and a low-level region by means of a step so that the shape pattern corresponding to the information signal is formed in the high-level region.
If some foreign matter exists in a high-level region of the master information carrier, uniform adhesion cannot be secured between the high-level region and the magnetic recording medium. Then, the master information carrier is washed. After being washed with a detergent such as pure water or an organic solvent, spin-drying is carried out by means of rotating the master information carrier at a high speed to remove the detergent by centrifugal force.
In such spin-drying, there is observed such a phenomenon that flow of the detergent becomes stagnant at an edge of the high-level region so that minute foreign matter contained in the detergent may stick to the edge. This phenomenon causes a problem if the foreign matter sticks to and resides on the surface of the high-level after washing.
If foreign matter thus sticks and resides, it is impossible to uniformly adhere the high-level region and the magnetic recording medium with each other, thus possibly damaging the surface of the magnetic recording medium or the surface of the high-level region in the master information carrier at adhering.
Therefore, a transferring and recording method of adhering the magnetic recording medium and the high-level region in which a ferromagnetic thin film pattern is formed in the master information carrier has an important subject of preventing detergent or foreign matter from stagnating at an edge of the high-level region during a detergent drying step for the master information carrier, for the purpose of improving the adhesion thereof.
Such a subject applies not only to a magnetic recording medium for magnetically recording/reproducing but also to an information recording medium of any other recording/reproducing types.
SUMMARY OF THE INVENTION
Accordingly, a main object of the present invention is to provide a high-reliability master information carrier which can uniformly adhere a high-level region and an information recording medium without damaging the information recording medium when an information signal such as a preformat information is transfer-wise recorded to the information recording medium such as a magnetic recording medium in a master information carrier.
Another object of the present invention is to provide a method for manufacturing a high-reliability information recording medium.
The invention about the master information carrier solves the above-mentioned problems by taking the following measures. The invention premises a structure of a master information carrier in which a region having a shape pattern corresponding to an information signal on the surface of a base member is provided as a high-level region higher than the other regions. In the master information carrier having this premised structure, a required area of a rising edge which defines the high-level region has such a shape that protrudes externally so as to promote flow of a detergent, e.g., a curved shape which protrude externally convex shape or a polygonal shape consisting of a plurality of straight lines so as to protrude externally convex shape. Such a shape is called a flow promoting shape.
Here, a high-level region on the base member surface refers to a relatively higher region in which an information signal is formed with respect to a relatively lower region (which is called a low-level region) in which an information signal is not formed. Further, the rising edge which defines the high-level region refers to a portion having a step which forms a boundary between the high-level and low-level regions on the base member surface. Further, the required area of the edge refers to an area where a detergent or foreign matter contained therein is liable to stagnate during a drying step after washing.
In short, the master information carrier of the present invention includes a base member, a high-level and low-level regions which are constituted with a step formed therebetween on the surface of the base member, a shape pattern corresponding to an information signal formed on the surface of the high-level region, and a flow promoting portion which is formed in a required area of an edge at a boundary defining the high-level and low-level regions and has a shaped protruding externally so as to promote the flow of a detergent.
The structure of the present invention has the following actions. The area where a detergent or foreign matter is liable to stagnate is the edge of the high-level region which extends perpendicularly or nearly perpendicularly with respect to the flow direction of the detergent. At such an area, smooth flow of the detergent tends to be blocked. Even if the flow of the detergent hits the edge, it is stopped and stagnates there and once it stagnates, the following detergent flow is stopped by this stagnant detergent and may not reach the edge. Then, the stagnated state becomes permanent. This means, in short, stagnation (see detergent-flow stagnating region
54
shown in FIG.
22
).
The above-mentioned stagnation is caused, as mentioned above, by a fact that the edge of the high-level region extends perpendicularly or nearly perpendicularly to a flow direction of a detergent. Then, in accordance with the present invention, a required area where a detergent or foreign matter contained therein is liable to stagnate is shaped as the flow promoting portion to protrude externally, i.e. opposite the flow of the detergent so as to promote the flow of the detergent without blocking it. By this protruding shape of the flow promoting portion, the flow of the detergent is promoted.
By such a countermeasure, it is possible to smooth the flow of a detergent at an area (position) where it is liable to be blocked, thereby preventing the detergent from stagnating therein. The detergent can thus be prevented from stagnating and therefore foreign matter contained therein can be prevented from being stagnated.
Here, a master information carrier in accordance with the present invention is reconfirmed as follows. The master information carrier is something like, so called an original text for initially recording an information signal of, e.g., preformat information on an information recording medium and has such a pattern (which is represented by a ferromagnetic thin film pattern) formed therein that c
Hashi Hideyuki
Ishida Tatsuaki
Miyata Keizo
Hudspeth David
Matsushita Electric - Industrial Co., Ltd.
McDermott Will & Emery LLP
Rodriguez Glenda P.
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