§
PatentCue
Patent Intelligence
Join Waitlist Sign In
← Back to Patent Explorer
US4705300A Expired / Lapsed US ⏱️ 0.0 years remaining

Thin film optically variable article and method having gold to green color shift for currency authentication

Assignee: Flex Products Inc
•
Filing: 1986-11-21
•
Granted: 1987-11-10
•
Expires: 2006-11-21
📄 Original PDF 🌐 Google Patents 🔄 Sync Now

Abstract

Abstract Thin film optical variable article to be used in a reflection mode having a gold to green color shift with angle for currency authentication and adapted to be carried by a substantially opaque currency sheet which serves as a substrate. The article includes a substantially transparent, optically thick element carrying a subtractive colorant and having first and second surfaces and a multilayer interference coating carried on one of said first and second surfaces. The article is adapted to be carried by the currency sheet so that the coating faces the currency sheet and the colorant carrying element serves as a superstrate facing the incident light. The multilayer interference coating is comprised of a substantially opaque layer of aluminum nearest the substrate, followed by a layer of magnesium fluoride, and then by a layer of chromium having substantial transmission. The colorant has a yellow hue. At normal incidence of light the article has a coppery-gold color shifting towards a vivid green at non-normal incidence of light. The colorant operates in an essentially subtractive mode in combination with the multilayer interference coating to provide the color shift from gold to green at two different angles of incidence and substantially no color at higher angles of incidence to cause a modification of the normal incidence gold color and the color shift with angle properties as seen by reflection.

Inventors

  • 👤 Peter H. Berning
  • 👤 Roger W. Phillips

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-08 17:33
CPC Classifications
B; B42; B42D; B42D25/00; B42D25/20; B42D25/29

Claims Analysis

Total Claims: 9
Claim 1
Independent Claim 213 words
In a thin film optical variable article to be used in a reflection mode having a gold to green color shift with angle for currency authentication and adapted to be carried by a substantially opaque currency sheet which serves as a substrate, the article comprising a substantially transparent, optically thick element carrying a subtractive colorant means and having first and second surfaces and a multilayer interference coating carried on one of said first and second surfaces and having an inherent color shift with angle, said article being adapted to be carried by the currency sheet so that the coating faces the currency sheet and the subtractive colorant carrying element serves as a superstrate facing the incident light, said multilayer interference coating being comprised of a substantially opaque layer of aluminum nearest the substrate, followed by a layer of magnesium fluoride, and then by a layer of chromium having substantial transmission, said subtractive colorant means having a yellow hue and in combination with the multilayer interference coating serving to modify the inherent color shift produced by the multilayer interference coating to provide at a normal angle of incident light a coppery-gold color and at a non-normal angle of incident light a vivid green and at higher non-normal angles of incident light substantially no color.
Claim 2
Dependent Claim 213 words
In a thin film optical variable article to be used in a reflection mode having a gold to green color shift with angle for currency authentication and adapted to be carried by a substantially opaque currency sheet which serves as a substrate, the article comprising a substantially transparent, optically thick element carrying a subtractive colorant means and having first and second surfaces and a multilayer interference coating carried on one of said first and second surfaces and having an inherent color shift with angle, said article being adapted to be carried by the currency sheet so that the coating faces the currency sheet and the subtractive colorant carrying element serves as a superstrate facing the incident light, said multilayer interference coating being comprised of a substantially opaque layer of aluminum nearest the substrate, followed by a layer of magnesium fluoride, and then by a layer of chromium having substantial transmission, said subtractive colorant means having a yellow hue and in combination with the multilayer interference coating serving to modify the inherent color shift produced by the multilayer interference coating to provide at a normal angle of incident light a coppery-gold color and at a non-normal angle of incident light a vivid green and at higher non-normal angles of incident light substantially no color.
Claim 3
Dependent Claim 19 words
An article as in claim 1 wherein the aluminum layer by itself has a transmittance of less than 0.1%.
Claim 4
Dependent Claim 18 words
An article as in claim 1 wherein said chromium layer by itself has a transmittance of approximately 30-40%.
Claim 5
Dependent Claim 22 words
An article as in claim 1 wherein said magnesium fluoride layer has an optical thickness of 4.3 quarterwaves ±5% at 550 nanometers.
Claim 6
Dependent Claim 16 words
An article as in claim 1 together with an adhesive layer carried by the aluminum layer.
Claim 7
Dependent Claim 14 words
An article as in claim 5 wherein said adhesive is non-tacky at room temperatures.
Claim 8
Dependent Claim 21 words
An article as in claim 1 together with a removable flexible film and release means carried by the colorant carrying layer.
Claim 9
Dependent Claim 24 words
An article as in claim 7 wherein said release means is in the form of a separate release layer carried by the flexible film.

References Cited (Backward Citations)

US3858977A Cited
US3852088A Cited
US3887742A Cited
US4455039A Cited
US4436377A Cited
US4501439A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1990-11-09 1991-05-11 1991-11-10 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1994-11-09 1995-05-11 1995-11-10 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1998-11-09 1999-05-11 1999-11-10 $7700.00 Window Closed / Lapsed

Assigned Categories & Tags

No categories assigned to this patent yet.

Assign Category Tag