Invention Grant
- Patent Title: Method of printing stealth white image, set of substrate and stealth ink, and printing device
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Application No.: US17097010Application Date: 2020-11-13
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Publication No.: US11701911B2Publication Date: 2023-07-18
- Inventor: Koji Katsuragi , Haruki Saitoh
- Applicant: RICOH COMPANY, LTD.
- Applicant Address: JP Tokyo
- Assignee: Ricoh Company, Ltd.
- Current Assignee: Ricoh Company, Ltd.
- Current Assignee Address: JP Tokyo
- Agency: Grüneberg and Myers, PLLC
- Priority: JP 19208109 2019.11.18 JP 20168912 2020.10.06
- Main IPC: B41M3/14
- IPC: B41M3/14 ; C09D11/40 ; C09D11/36 ; B41J2/175 ; B41J29/13 ; B42D25/387 ; C09D11/50 ; C09D11/322 ; B41M3/00

Abstract:
A method of printing a stealth white image includes applying a stealth ink containing a red coloring material that emits visible light at exposure to ultraviolet radiation and a green coloring material that emits visible light at exposure to ultraviolet radiation to a substrate which contains a fluorescent brightener to form the stealth white image thereon, wherein the stealth white image demonstrates an a* value of from −2.0 to 2.0 and a b* value of from −10.0 to 0 at exposure to ultraviolet radiation having a wavelength of 370 nm according to CIE 1976 L*a*b* colorimetric system.
Public/Granted literature
- US20210146708A1 METHOD OF PRINTING STEALTH WHITE IMAGE, SET OF SUBSTRATE AND STEALTH INK, AND PRINTING DEVICE Public/Granted day:2021-05-20
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