Inductor devices – Coil or coil turn supports or spacers – Printed circuit-type coil
Reexamination Certificate
2002-07-12
2004-02-17
Donovan, Lincoln (Department: 2832)
Inductor devices
Coil or coil turn supports or spacers
Printed circuit-type coil
C428S323000
Reexamination Certificate
active
06693506
ABSTRACT:
This application claims priority to Japanese Patent Application Number JP2001-228542 filed Jul. 27, 2001 which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic sticking sheet able to be supplied in a rolled state and a method of producing the sheet, more particularly relates to a magnetic sticking sheet suitable for printing by the sheet by feeding it from the rolled state and a method of producing the sheet.
2. Description of the Related Art
Magnetic sticking sheets using magnetic attraction of a magnet are widely used as various types of display tools. Particularly, they are widely used in offices.
In recent years, along with the rapid spread of personal computers, the performance of printers and other peripherals has been remarkably improved. The printing quality of personal printers is becoming comparable to the printing quality of business printers. In the field of business printers, demand for printers able to print on large size paper such as A0, A1, B0, B1 size paper has increased. At the same time, there is a growing desire to use such large size printed matter.
The most important use of large sized printed matter is posters. Posters are fixed to bulletin boards using various types of adhesives, adhesive tape, thumb tacks, capped magnets, and other fasteners. A magnetic sticking sheet poster is convenient in that the poster itself is a fastener having a magnetic sticking property. If the bulletin board has a ferromagnetic surface, no other fastener is needed. That is, the sheet can be fastened to the bulletin board on its own. Also, the sheet can be freely peeled off from the bulletin board.
Generally, magnetic sticking sheets are sheet type bond magnets. Along with their expanded applications, sheet type bond magnets have been made thinner. In recent years, magnetic sticking sheets produced by extrusion or injection molding having a thickness of the magnetic layer of about 0.1 mm and a total thickness of about 0.25 mm have been commercialized. These magnetic sticking sheets have axes of easy magnetization oriented perpendicularly to the surface of the magnetic layer and are magnetized perpendicularly. For example, U.S. Pat. No. 6,312,795 discloses a magnetic sheet of this type.
FIG. 1
shows schematically the magnetic layer
2
of the magnetic sticking sheet having an axis of easy magnetization perpendicular to the surface of the magnetic layer. As shown in
FIG. 1
, the magnetic layer
21
and attachment
9
are attached magnetically. The magnetic layer
21
is multipolar-magnetized at a certain pitch of magnetic poles. The N-poles and S-poles arranged alternately at an interface between the magnetic layer
21
and the attachment
9
generate a magnetic field shown by the magnetic lines of force
22
.
A magnet generates a magnetic field outside it due to the N-poles and S-poles. On the other hand, the magnet also generates a magnetic field inside it due to the same magnetic poles. This is called a “demagnetizing field”. The demagnetizing field faces the magnetic circuit formed by the outer magnetic field, so acts to demagnetize the magnet itself.
In the way that a magnetic field becomes stronger the shorter the distance between the N-S magnetic poles, the demagnetizing field becomes stronger and the magnet becomes more easily demagnetized the shorter the distance between the N-S magnetic poles.
As shown in
FIG. 1
, the conventional magnetic sticking sheet oriented and magnetized perpendicularly to the surface of the magnetic layer has a distance between magnetic poles equal to the thickness of the magnetic layer. Therefore, in order to increase the distance between magnetic poles and reduce the demagnetizing field, the thickness of the magnetic layer must be increased. On the other hand, when thinning the magnetic layer for the purpose of improving easiness of cutting and/or handling of the magnetic sticking sheet, the distance between magnetic poles consequently becomes short and demagnetizing field increases. Therefore, it becomes easy to be demagnetized.
Also, in the production of magnetic sticking sheets by extrusion, a paste containing a mixture of a particle type magnetic material and binder is processed at a high temperature and high pressure, so the equipment becomes large in size. In the case of injection molding, the thinner the magnetic sticking sheet, the more difficult it is to form and the greater the load on the equipment.
Further, since the conventional magnetic sticking sheet oriented and magnetized perpendicularly to the surface of the magnetic layer is so thick in total thickness as to be hard to roll and its magnetic sticking force is as high as 1.0 gf/cm
2
or more, printing by printers for personal or business use is difficult. If printing on such magnetic sticking sheets by a printer for personal or business use in the same manner as printing on normal paper, the sheets would stick to each other making precise alignment and smooth feed impossible.
Particularly, when rolling magnetic sticking sheets having too strong a magnetic sticking force, the ends of the roll will become uneven or the roll will become slack. If magnetic sticking sheets are fed into a printer from a roll with uneven ends or having slackness, the magnetic sticking sheets will not be precisely positioned.
On the other hand, Japanese Patent No. 1460017 discloses a method of producing a magnetic sticking sheet including a step of coating a magnetic coating material containing magnetic particles to form a magnetic layer having a thickness of 0.1 to 0.3 mm, a step of orienting an axis of easy magnetization longitudinally (in-plane or parallel to a surface of the magnetic layer), and a step of multipolar-magnetization. It is described that the magnetic sticking force after magnetization is insufficient when the thickness of the magnetic layer is less than 0.1 mm. In practice, a sufficient magnetic sticking force is observed only at a 0.2 mm thickness of the magnetic layer in the embodiments of the patent. There is no description about the desirable squareness ratio in this patent. In this patent, a capacitor and yoke are used for magnetization.
In Japanese Unexamined Patent Publication (Kokai) No. 2001-76920 too, a flexible magnetic sheet having a magnetic film formed by coating a magnetic coating material containing hard magnetic particles is described. The flexible magnetic sheet has an axis of easy magnetization oriented longitudinally and is multipolar-magnetized longitudinally. In this publication, as an example of the method of multipolar-magnetization of the magnetic layer in a longitudinal direction, a method using a capacitor and yoke is mentioned.
This flexible magnet sheet can be made uniformly thin and be printed. As an example in the publication, a flexible magnetic sheet having a thickness of the magnetic layer of 0.07 mm and a sticking force of about 240 N/m
2
(≈2.4 gf/cm
2
) is described.
The publication gives as examples including printing an example of printing a sheet cut to the A4 type size by a printer and an example of printing a sheet cut to a tape form by a thermal transfer type label writer. The publication does not describe a roll type sheet of a large size such as A0 applicable to high quality printing. Also, it does not investigate the characteristics of a magnetic sticking sheet suitable for feeding in a printer from a rolled state. When rolling a sheet having a magnetic sticking force equal to that of the above examples of the publication, their magnetic attraction force is too strong, the magnetic repulsive force has an effect, and shaping the roll becomes difficult. Therefore, it is impossible to print it normally by a printer.
When printing on paper having a size of for example A3 to A5, B4, B5, or so, a stack of paper cut in advance to the predetermined size is often used. In the case of an A0 type or other large size paper printer, however, if the paper is pre-cut and stacked, the area occupied by the printer will become remarkably large. Therefore, at pre
Kawamata Kazuto
Matsumura Shinichi
Ohta Eiji
Sudo Miki
Depke Robert J.
Donovan Lincoln
Holland & Knight LLC
Nguyen Tuyen T.
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