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US 6,731,111 B2Granted
Validity determination using magnetic ink having magnetic powders with different Curie temperatures
AssigneeKabushiki Kaisha Toshiba
InventorsTakao Sawa, Katsutoshi Nakagawa, Teruo Murakami, Tadahiko Kobayashi, Hisashi Takahashi, Masao Obama
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Abstract
The magnetic powder for validity determining ink is composed of magnetic oxide powder having a Curie temperature between −50° C. and 150° C. and a mean powder particle diameter of 10 μm or less.
Claims5
A detecting method for a printing member for validity determination, comprising:
- conveying a printing member for validity determination having a first magnetic image printed with first magnetic ink including first magnetic powder having a first Curie temperature and a second magnetic image printed with second magnetic ink including second magnetic powder having a second Curie temperature higher than the same of the first magnetic powder;
- heating the printing member for validity determination to a temperature higher than the first Curie temperature and lower than the second Curie temperature;
- and
- detecting magnetic characteristics from the heated printing member for validity determination.
1 more element
Dependencies are inferred from the claim text.