Multilayer optical films having side-by-side polarizer/polarizer zones

• US 9,291,757 B2
• Filed: 12/22/2009
• Issued: 03/22/2016
• Est. Priority Date: 12/22/2008
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Merrill, William Ward, Dunn, Douglas S.
• Primary Examiner(s): Allen, Stephone B
• Assistant Examiner(s): DABBI, JYOTSNA V
• Application Number:
  US13/139,866
• Publication Number:
  US 20110286095A1
• Time in Patent Office: 2,282 Days
• Field of Search: 359/483.01, 359/486.01, 359/486.02, 359/489.07, 359/489.15, 359/489.16, 359/489.17, 362/19, 353/20, 264/1.1, 264/1.31, 264/1.34, 264/1.35, 264/1.36, 264/1.37, 264/482, 427/553, 427/554, 427/555, 427/595, 427/596, 427/162, 427/163.1
• US Class Current: 1/1
• CPC Class Codes: B42D 25/23 Identity cards
• CPC Class Codes: B42D 25/24 Passports
• CPC Class Codes: B42D 25/391 absorbing or reflecting polarised light
• CPC Class Codes: G02B 27/28 for polarising used in stereoscopes G02B30/25
• CPC Class Codes: G02B 5/0816 Multilayer mirrors, i.e. having two or more reflecting layers G02B5/0883, G02B5/0891 take precedence
• CPC Class Codes: G02B 5/0841 comprising organic materials, e.g. polymers
• CPC Class Codes: G02B 5/285 comprising deposited thin solid films G02B5/281 - G02B5/289 take precedence; multilayered film filters for fibre optic multiplexing G02B6/29361
• CPC Class Codes: G02B 5/287 comprising at least one layer of organic material
• CPC Class Codes: G02B 5/30 Polarising elements light-modulating devices with active elements G02F1/00
• CPC Class Codes: G02B 5/3041 comprising multiple thin layers, e.g. multilayer stacks
• CPC Class Codes: G02B 5/305 including organic materials, e.g. polymeric layers
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001
• CPC Class Codes: G02F 1/133521 Interference filters
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree

Abstract

A reflective film includes interior layers that selectively reflect light by constructive or destructive interference, the layers extending from a first to a second zone of the film. In the first zone the layers provide a first reflective polarizer characteristic, and in a second zone the layers provide a substantially different reflective polarizer characteristic. The second zone is characterized by at least some of the layers having a reduced birefringence relative to their birefringence in the first zone. In some cases the first reflective polarizer characteristic may have a pass axis that is substantially orthogonal to that of the second reflective polarizer characteristic. The film may have substantially the same thickness in the first and second zones, or a substantially reduced thickness in the second zone relative to the first zone.

Claims

1. An optical film comprising:

a combination of substantially orthogonally oriented reflective polarizers that are both formed from a same plurality of layers, the plurality of layers arranged to selectively reflect light by constructive or destructive interference,

wherein the plurality of layers comprises a first set of layers that are birefringent in one or more first zones of the optical film corresponding to a first reflective polarizer, and the first set of layers has a reduced or eliminated birefringence in one or more second zones of the optical film relative to its birefringence in the one or more first zones, the first and second zones being adjacent with each and the plurality of layers extending from the first zones to the second zones, the one or more second zones of the optical film corresponding to a second reflective polarizer that is substantially orthogonally oriented relative to the first reflective polarizer,

wherein the reduced or eliminated birefringence of the first set of layers in the second zones relative to the first zones causes the second reflective polarizer to be substantially orthogonally oriented relative to the first reflective polarizer, and

wherein the plurality of layers has substantially the same thickness in the one or more first zones and the one or more second zones.

2. The film of claim 1, wherein the combination of reflective polarizers comprises the first reflective polarizer formed in the one or more first zones of the optical film, and the second reflective polarizer formed in the one or more second zones of the optical film, and the first and second reflective polarizers are respectively oriented along two orthogonal in-plane directions.

3. The film of claim 1, wherein the plurality of layers is characterized by smooth interfaces between the layers.

4. The film of claim 1, wherein the plurality of layers further comprises a second set of layers that substantially maintains their birefringence in the second zones relative to their birefringence in the first zones.

5. A security construction comprising the optical film of claim 1, wherein the security construction comprises an identification card, a driver'"'"'s license, a passport, an access control pass, a financial transaction card, or a brand protection or identification label.

6. A display comprising the optical film of claim 1.

7. A multilayer optical film, comprising:

a plurality of interior layers arranged to selectively reflect light by constructive or destructive interference to provide a first reflective characteristic;

wherein the plurality of interior layers comprises a first set of layers composed of a first material and a second set of layers composed of a second material different from the first material, the first and second materials having different melting or softening temperatures allowing the first and second sets of layers to reduce birefringence by heating at different temperatures, the first and second sets of layers both being birefringent and extending from a first zone to a second zone;

wherein the film has an absorption characteristic tailored to heat the interior layers, in response to the film being illuminated with a suitable light beam, sufficiently to reduce a birefringence of at least some of the interior layers in the second zone while maintaining a structural integrity of the plurality of interior layers, such reduction in birefringence being sufficient to change the first reflective characteristic in the first zone to a different second reflective characteristic in the second zone; and

wherein the first reflective characteristic is substantially a first polarizer characteristic, and the second reflective characteristic is a second polarizer characteristic substantially different from the first polarizer characteristic,

wherein the plurality of interior layers has substantially the same thickness in the first zone and the second zone.

8. The film of claim 7, wherein the second polarizer characteristic has a pass axis oriented substantially orthogonally relative to a pass axis of the first polarizer characteristic.

9. The film of claim 7, wherein the first and second polarizer characteristics have respective first and second reflection bands associated therewith for normally incident light, and wherein the absorption characteristic is associated with an absorbing agent, and wherein the absorbing agent preferentially absorbs light at wavelengths other than the first and second reflection bands.

10. The film of claim 7, wherein the first set of layers has a reduced birefringence in the second zone relative to their birefringence in the first zone, and the second set of layers substantially maintains their birefringence in the second zone relative to their birefringence in the first zone.