Retroreflective articles and devices having viscoelastic lightguide

• US 9,851,482 B2
• Filed: 06/17/2015
• Issued: 12/26/2017
• Est. Priority Date: 07/10/2008
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Sherman, Audrey A., Boulos, Marie A., Meis, Michael A., Schaffer, Kevin R., Tran, Thu-Van T.
• Primary Examiner(s): Wong, Tina
• Application Number:
  US14/741,503
• Publication Number:
  US 20150316693A1
• Time in Patent Office: 923 Days
• Field of Search: None
• CPC Class Codes: G02B 5/128 transparent spheres being embedded in matrix
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G09F 13/0472 Traffic signs
• 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

Abstract

Disclosed herein is an optical device having a light source, a viscoelastic lightguide and a retroreflective film suitable for retroreflecting light. Light from the light source enters the viscoelastic lightguide and is transported within the lightguide by total internal reflection. The optical device may have a “front lit” configuration such that light being transported within the lightguide is extracted and retroreflected by the film toward a viewer. The optical device may have a “back lit” configuration such that light being transported within the lightguide is extracted and transmitted through the film toward a viewer. The retroreflective film may comprise beaded retroreflective sheeting such as that used in traffic signs and markings.

Claims

1. An optical device comprising:

a light source;

a viscoelastic lightguide, wherein light emitted by the light source enters the viscoelastic lightguide and is transported within the lightguide by total internal reflection; and

a retroreflective film suitable for retroreflecting light and comprising

a layer of transparent microspheres and

reflective material disposed in back of the layer;

wherein the viscoelastic lightguide is disposed in front of the layer of transparent microspheres such that light being transported within the viscoelastic lightguide is extracted from the lightguide and retroreflected by the transparent microspheres;

wherein the optical device is flexible; and

wherein the viscoelastic lightguide has a storage modulus of less than about 300,000 Pascal, measured at 10 rad/sec and a temperature of from about 20 to about 22°

C.

2. A shelf, comprising the optical device of claim 1.

3. A vehicle, comprising the optical device of claim 1.

4. A display device, comprising the optical device of claim 1.

5. The optical device of claim 1, wherein the viscoelastic lightguide is compliant.

6. The optical device of claim 5, wherein the viscoelastic lightguide has a storage modulus of between about 30 Pascals and about 300,000 Pascals, measured at 10 rad/sec and a temperature of from about 20 to about 22°

C.

7. An optical device comprising:

a light source and an optical device, the optical device comprising;

a viscoelastic lightguide, wherein light emitted by the light source enters the viscoelastic lightguide and is transported within the lightguide by total internal reflection; and

a retroreflective film suitable for retroreflecting light and comprising

a layer of transparent microspheres, and

reflective material associated with each transparent microsphere and disposed in back of each transparent microsphere;

wherein the viscoelastic lightguide is disposed in front of the layer of transparent microspheres such that light being transported within the viscoelastic lightguide is extracted from the lightguide and retroreflected by the transparent microspheres,

wherein the viscoelastic lightguide comprises a pressure sensitive adhesive;

wherein the light emitted by the light source is transported within the pressure sensitive adhesive of the viscoelastic lightguide; and

the reflective material associated with each transparent microsphere forms an individual image, a composite image is formed by the individual images such that the composite image appears to the unaided eye to float in front of the layer of transparent microspheres, and the composite image has more than one color.

8. The optical device of claim 7, wherein at least one of the first viscoelastic lightguide is compliant.

9. The optical device of claim 8, wherein the viscoelastic lightguide has a storage modulus of less than about 300,000 Pascal, measured at 10 rad/sec and a temperature of from about 20 to about 22°

C.

10. The optical device of claim 8, wherein the viscoelastic lightguide has a storage modulus of between about 30 Pascals and about 300,000 Pascals, measured at 10 rad/sec and a temperature of from about 20 to about 22°

C.

11. An optical article, comprising:

a first light source;

a second light source;

a first viscoelastic lightguide, wherein light emitted by the first light source enters the first viscoelastic lightguide and is transported within the lightguide by total internal reflection;

a second viscoelastic lightguide, wherein light emitted by the second light source enters the second viscoelastic lightguide and is transported within the lightguide by total internal reflection;

a first retroreflective film suitable for retroreflecting light comprising

a layer of transparent microspheres and

reflective material disposed in back of the layer; and

a second retroreflective film suitable for retroreflecting light comprising

a layer of transparent microspheres and

reflective material disposed in back of the layer;

wherein the first viscoelastic lightguide is disposed in front of the layer of transparent microspheres of the first retroreflective film such that light being transported within the first viscoelastic lightguide is extracted from the lightguide and retroreflected by the transparent microspheres of the first retroreflective film;

wherein the second viscoelastic lightguide is disposed in front of the layer of transparent microspheres of the second retroreflective film such that light being transported within the second viscoelastic lightguide is extracted from the lightguide and retroreflected by the transparent microspheres of the second retroreflective film; and

wherein both the first retroreflective film and the second retroreflective film are disposed between the first viscoelastic lightguide and the second viscoelastic lightguide.

12. The optical article of claim 11, wherein at least one of the first viscoelastic lightguide or the second viscoelastic lightguide is compliant.

13. The optical article of claim 12, wherein the at least one of the first viscoelastic lightguide or the second viscoelastic lightguide has a storage modulus of less than about 300,000 Pascal, measured at 10 rad/sec and a temperature of from about 20 to about 22°

C.

14. The optical article of claim 12, wherein the at least one of the first viscoelastic lightguide or the second viscoelastic lightguide has a storage modulus of between about 30 Pascals and about 300,000 Pascals, measured at 10 rad/sec and a temperature of from about 20 to about 22°

C.