High contrast retroreflective sheeting and license plates

• US 9,937,879 B2
• Filed: 08/19/2015
• Issued: 04/10/2018
• Est. Priority Date: 10/08/2009
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Fleming, Patrick R., Dahlin, Thomas J., Kusilek, Thomas V., Smithson, Robert L.
• Primary Examiner(s): Phan, James
• Application Number:
  US14/830,421
• Publication Number:
  US 20150353029A1
• Time in Patent Office: 965 Days
• Field of Search: 359530-533
• CPC Class Codes: B60R 13/10 Registration, licensing, or like devices
• CPC Class Codes: G02B 5/12 Reflex reflectors
• CPC Class Codes: G06V 20/62 Text, e.g. of license plates, overlay texts or captions on TV images
• CPC Class Codes: G06V 30/224 of printed characters having additional code marks or containing code marks
• CPC Class Codes: G09F 13/16 Signs formed of or incorporating reflecting elements or surfaces, e.g. warning signs having triangular or other geometrical shape
• CPC Class Codes: Y10T 428/24355 Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
• CPC Class Codes: Y10T 428/24802 Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]

Abstract

The present disclosure relates to the formation of high contrast, wavelength independent retroreflective sheeting made by including a light scattering material on at least a portion of the retroreflective sheeting. The light scattering material reduces the brightness of the retroreflective sheeting without substantially changing the appearance of the retroreflective sheeting when viewed under scattered light.

Claims

1. A retroreflective article comprising:

a retroreflective sheeting comprising indicia including a light scattering material, wherein the light scattering material is placed under the indicia; and

wherein the light scattering material is the same color as the retroreflective sheeting.

2. A license plate comprising the retroreflective article of claim 1.

3. An optical character recognition system, comprising:

an optical character recognition camera;

a light source emitting infra-red light that is coaxial with the optical character recognition camera; and

the retroreflective sheeting of claim 1;

wherein the retroreflective sheeting is irradiated using the light source and imaged using the optical character recognition camera thereby recognizing characters of the indicia.

4. The optical character recognition system of claim 3, wherein the light scattering material is a surface-scattering material.

5. The optical character recognition system of claim 3, wherein the light scattering material is one of an ink, a toner, a dye, and a tape.

6. The optical character recognition system of claim 3, wherein the light scattering material is a surface that has been selectively roughened.

7. The optical character recognition system of claim 3, wherein the light scattering material is one of colored, clear, and white.

8. The optical character recognition system of claim 3, wherein the retroreflective sheeting is disposed on at least a portion of a license plate.