Method for labeling products with a transparent photoluminescent label, and transparent photoluminescent label

Patent metadata

Field	Value
Publication number	US-10752043-B2
Application number	US-201515758281-A
Country	US
Kind code	B2
Filing date	Nov 23, 2015
Priority date	Nov 23, 2015
Publication date	Aug 25, 2020
Grant date	Aug 25, 2020

Abstract

A method for marking a product ( 1 ) with a photoluminescent mark, said mark comprising a photoluminescent portion ( 10 ) which is transparent under normal light conditions and revealed by photoluminescence under UV illumination, said mark further comprising a non photoluminescent portion ( 9 ) which is transparent under normal light conditions as well as under UV illumination, said method comprising: deposing on said product a stack, said stack comprising alternatively layers ( 2, 4 ), such as AlN, with a thickness of less than 1 micron and layers ( 3 ) of a second material, such as GaN, with a thickness of less than 10 nm; raising the transparency of said non photoluminescent portion ( 10 ) with a deposition of transparent material ( 6 ) or incorporation of ions into said non photoluminescent portions.

First claim

The invention claimed is:

1. A method for labeling a product with a photoluminescent label, said label comprising a photoluminescent portion which is transparent under normal light conditions and revealed by photoluminescence under UV illumination, said label further comprising a non photoluminescent portion which is transparent under normal light conditions as well as under UV illumination,
wherein said method comprises:
deposing on said product a stack, said stack comprising successive pairs of layers, each pair of layers comprising a first layer of a first material with a thickness of less than 1 micron and a second layer of a second material with a thickness less than 10 nm, resulting in quantum nano-structures at the interface between the first layer and the second layer of the pairs of layers,
incorporating ions or deposing a transparent material into said non photoluminescent portions.

2. The method of claim 1 , wherein said stack comprises fewer than or equal to 100 layers.

3. The method of claim 1 , wherein said first and second layers are grown by sputtering, Atomic Layer deposition, Molecular Beam Epitaxy, or Metal Organic Chemical Vapor Deposition, thereby forming a grown stack.

4. The method of claim 3 , comprising roughening the grown stack to form said quantum nano-structures.

5. The method of claim 1 , wherein said second layers of second material comprise GaN alloys with less than 50% of Indium, Aluminum, Arsenic and/or Phosphor.

6. The method of claim 1 , wherein said second layers of second material comprise less than or equal to 10% rare-earth elements.

7. The method of claim 1 , wherein said quantum nano-structures comprise quantum dots.

8. The method of claim 1 , wherein said first layers of first material comprise less than 20% of Magnesium, Silicon, Lithium, Beryllium, Cadmium and/or Zinc as dopant elements.

9. The method of claim 1 , wherein said ions include Oxygen, Nitrogen, Hydrogen, Helium, Neon, Argon, Magnesium, Lithium, Beryllium, Boron, Phosphor, Aluminum, Zinc, Arsenic, Gallium, Silicon, or Cadmium.

10. The method of claim 1 , wherein said ions are incorporated within the stack by diffusion or implantation techniques.

11. The method of claim 1 , wherein said ions are incorporated through a mask so as to create a pattern.

12. The method of claim 1 , wherein said transparent material replaces selectively removed photoluminescent portions.

13. The method of claim 12 , wherein said transparent material has a refractive index substantially equal to the refractive index of said stack.

14. The method of claim 1 , wherein the method comprises creating a unique pattern for each product using a one-time mask.

15. The method of claim 1 , wherein the photoluminescent portions reemitted light color depends on the intensity of incoming UV light.

16. The method of claim 1 , wherein said UV illumination comprises UV wavelengths of less than or equal 400 nm.

Assignees

• Ecole Polytechnique Fed De Lausanne (Epfl)

Inventors

• Hefyene Nasser
• Grandjean Nicolas

Classifications

• B42D25/387 Primary

  absorbing or reflecting ultraviolet light · CPC title

• G09F2003/0213

  Concealed data · CPC title

• G09F3/0294

  where the change is not permanent, e.g. labels only readable under a special light, temperature indicating labels and the like · CPC title

• B42D25/373

  Metallic materials · CPC title

• G04B39/006

  out of wear resistant material, e.g. sapphire · CPC title