Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Including a second component containing structurally defined...
Patent
1987-12-16
1990-06-19
Schwartz, Pamela R.
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Including a second component containing structurally defined...
427 47, 427128, 428195, 428206, 428329, 428484, 4284881, 428692, 428900, 428913, 428914, B41M 520
Patent
active
049352997
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an ink medium for use in a printing method forming visible images by employing magnetic attraction force generating means.
TECHNICAL BACKGROUND
Up to now, a printing method utilizing magnetic ink medium has been suggested as a small-sized and low cost non-impact type printing method. For example, Japanese Patent Laid-Open No. 96541/77 describes a thermal transfer method wherein a magnetic attraction force acts on ink on a transfer medium corresponding to heat image by a magnetic means which is provided apart from a heat supply means. One of the ink media utilized in such method is described in Japanese Patent Laid-Open No. 36596/84.
However, when the transfer meidum described in Japanese Patent Laid-Open No. 36596/84 is employed for the printing method described in Japanese Patent Laid-Open No. 96541/77, ink is not transferred onto transfer paper sufficiently when magnetic force acts on the transfer medium to achieve transfer. This results in printing a broken line when a solid line is required, and normal letter form is not achieved when literal form is required.
This method is particularly disadvantageous and results in poor transfer which becomes more noticable when transfer paper having inferior surface smoothness is utilized.
Therefore, in order to solve the above disadvantages, the object of the present invention is to achieve high quality letter and image printing even on the transferred medium having inferior surface smoothness and to display completely the advantages of printing apparatus utilizing magnetic ink medium which conducts printing utilizing magnetic force.
SUMMARY OF THE INVENTION
The transfer medium of the present invention includes a magnetic ink layer 12 containing two types of magnetic particles different from each other in size, 21 and 22, formed on a support member 11 as shown in FIG. 1.
The magnetic ink layer is a thermoplastic material (generally, organic material) containing magnetic particles.
Substances having ferromagnetic properties, magnetic fine particles of metal or alloy such as .gamma.-Fe.sub.2 O.sub.3, FeO-Fe.sub.2 O.sub.3, Mn-Zn-Fe.sub.2 O.sub.3, Ni-Zn-Fe.sub.2 O.sub.3, are used as the magnetic fine particles. Such magnetic fine particles are in pulverized form under normal conditions.
Further, it is desirable to include two kinds of magnetic particles, one having a small particle size diameter of 0.01 to 1 .mu.m and the other a large particle size greater than 1 to 50 .mu.m, in the magnetic ink layer. The mixing ratio of these particles is from 1:15 to 5:1.
Furthermore, the large particle size magnetic particles can be linearly shape. In this case, preferable ratio of the major axis to the minor axis is from 3:1 to 20:1.
In addition, the ratio of magnetic particles contained in the magnetic ink layer is preferably from 5 to 70 wt% of the whole weight of the ink layer.
Such a transfer medium can be utilized not only for a printing apparatus wherein a transfer medium contacts a transferred medium at the printing portion at which transferring is carried out by fusing a magnetic ink layer and applying a magnetic field, but also in an apparatus wherein the transfer medium does not contact the transferred medium for printing.
Therefore, extremely high quality transferring can be carried out by mixing two types of magnetic particles having different particle size in the magnetic ink layer.
The reason is that although magnetic particles have larger magnetic force in proportion to the diameter thereof and have very strong attraction force in the magnetic field, when only large-sized magnetic particles are contained in the magnetic ink layer, only magnetic particles move and aggregate when the magnetic ink layer fuses and is transferred onto the transferred medium by the magnetic field. Thus, the thermoplastic resin layer in the magnetic ink layer is not transferred. As a result, only extremely small-sized dots can be formed and characters, pictures and the like can not be formed with continuous lines.
On the contrary, w
Fukushima Hitoshi
Iwamoto Kohei
Takei Katsumori
Yamaguchi Yoshitaka
Schwartz Pamela R.
Seiko Epson Corporation
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