Color display with molecular light valve

• US 20030231374A1
• Filed: 06/13/2002
• Published: 12/18/2003
• Est. Priority Date: 06/13/2002
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Williams, R. Stanley, Vincent, Kent D., Zhang, Xiao-An
• Granted Patent: US 6,853,478 B2
• Time in Patent Office: Days
• US Class Current: 359/321
• CPC Class Codes: G02F 1/0018 Electro-optical materials
• CPC Class Codes: G02F 1/061 based on electro-optical organic material G02F1/07, G02F1/13 take precedence
• CPC Class Codes: G02F 2201/12 electrode

Abstract

A molecular light valve mechanism is used for imaging on an adjacent pixel-patterned construct. An electrical fringe field or through field is used to transform targeted pixels by switching light valve molecules between a first non-transparent state and transparent state, providing information content on the adjacent pixel-patterned imaging layer.

Claims

1. A print medium comprising:

a substrate;

a molecular light valve construction conformed with said substrate, wherein molecules of the light valve construction are selectively switchable between a_transparent state and non-transparent state under influence of a localized electric field; and

conformed with said molecular light valve, an imaging construction having an addressable color mosaic pattern for forming picture elements.

2. The medium as set forth in claim 1 comprising:

said molecules are switchable between the transparent state and a black state.

3. The medium as set forth in claim 1 comprising:

said molecules are switchable between the transparent state and a white state.

4. The medium as set forth in claim 1 comprising:

said molecular light valve construction is an overlay for said pattern wherein said pattern is a mosaic pattern of primary color picture elements.

5. The medium as set forth in claim 1 comprising:

said molecules exhibit an electric field induced band gap change.

6. The medium as set forth in claim 5 wherein said electric field induced band gap change occurs via a mechanism selected from a group including (1) molecular conformation change or an isomerization, (2) change of extended conjugation via chemical bonding change to change the band gap, and (3) molecular folding or stretching.

7. The medium as set forth in claim 5 wherein said electric field induced band gap change occurs via a molecular conformation change or an isomerization.

8. The medium as set forth in claim 7 wherein the molecules forming the molecular light valve construction further comprise:

at least one stator portion and at least one rotor portion, wherein said rotor rotates from a first state to a second state with an applied electric field, wherein in said first state, there is extended conjugation throughout said molecular system, resulting in a relatively smaller band gap, and wherein in said second state, said extended conjugation is destroyed, resulting in a relatively larger band gap.

9. The medium as set forth in claim 8 comprising:

dependent upon direction of electrical field applied, in the first state said molecules are in a more conjugated state having a relatively smaller band gap, and in the second state said colorant molecules are in a less conjugated state, having a relatively larger band gap.

10. The medium as set forth in claim 5 wherein said electric field induced band gap change occurs via a change of extended conjugation via chemical bonding change to change the band gap.

11. The medium as set forth in claim 5 wherein said electric field induced band gap change occurs via a change of extended conjugation via charge separation or recombination accompanied by increasing or decreasing band localization.

12. The medium as set forth in claim 11 wherein a change from a first state to a second state occurs with an applied electric field, said change involving charge separation in changing from said first state to said second state, resulting in a relatively larger band gap state, with less π

-delocalization, and recombination of charge in changing from said second state to said first state, resulting in a relatively smaller band gap state, with greater π

-delocalization.

13. The medium as set forth in claim 10 wherein said electric field induced band gap change occurs via a change of extended conjugation via charge separation or recombination and π

-bond breaking or formation.

14. The medium as set forth in claim 13 wherein a change from a first state to a second state occurs with an applied electric field, said change involving charge separation in changing from said first state to said second state, wherein in said first state there is extended conjugation throughout, resulting in a relatively larger band gap state, and wherein in said second state said extended conjugation is destroyed and separated positive and negative charges are created, resulting in a relatively smaller band gap state.

15. The medium as set forth in claim 5 wherein said electric field induced band gap change occurs via a molecular folding or stretching.

16. The medium as set forth in claim 15 comprising:

said molecules have three portions, a first portion and a third portion, each bonded to a second, central portion, wherein a change from a first state to a second state occurs with an applied electric field, said change involving a folding or stretching about of said second portion, wherein in said first state there is extended conjugation, resulting in a relatively smaller band gap state, and wherein in said second state, said extended conjugation is destroyed, resulting in a relatively larger band gap.

17. The medium as set forth in claim 1 comprising:

said molecules are bistable, providing a non-volatile component.

18. The medium as set forth in claim 1 comprising:

said molecules have a low activation barrier between different said states providing a fast volatile switch.

19. The medium as set forth in claim 2 wherein said molecules are distributed across said substrate as an underlay of said imaging construction, said imaging construction further comprising a mosaic pattern of primary color filters arranged as said picture elements.

20. The medium as set forth in claim 19 wherein the substrate is configured for backlighting said filters.

21. The medium as set forth in claim 1 comprising:

said substrate is a material that is both flexible and durable for repeated imaging.

22. The medium as set forth in claim 21 wherein said flexible material is configured as a cut sheet print medium.

23. The medium as set forth in claim 21 wherein said flexible material is configured as a web print medium.

24. The medium as set forth in claim 1 wherein said substrate is constructed as a rigid, rewritable, display screen.

25. A method for writing on electrical field addressable rewritable medium, the method comprising:

forming a substrate having a molecular filtering layer wherein molecules of the coating are bi-stateable_and subjectable to switching between transparent and opaque states under influence of addressable, localized, electric fields; and

electrically addressing picture elements by selectively controlling each of said fields to form document content on said medium with said mosaic.

26. A method of fabricating rewritable media, the method comprising:

positioning a substrate;

forming with said substrate, an electrically addressable light valve layer wherein the layer is formed by a molecular system, said system including electrochromic switchable molecules, each of said molecules being selectively switchable between a transparent state and an opaque state; and

adjacent said light valve layer, forming an imaging layer having a color mosaic pattern of picture elements.

27. The method as set forth in claim 26 wherein said molecules exhibit an electric field induced band gap change.

28. The method as set forth in claim 27 wherein said electric field induced band gap change occurs via a mechanism selected from a group including (1) molecular conformation change or an isomerization, (2) change of extended conjugation via chemical bonding change to change the band gap, and (3) molecular folding or stretching.

29. An imaging display system comprising:

a substrate;

an imaging pattern of color pixels regions on one surface of the substrate;

superposing the imaging pattern, a molecular light valve layer having bimodal properties rendering each molecule either substantially transparent or substantially opaque;

a mechanism for addressing the regions by applying selective electrical fields to said layer for switching selected molecules such that images are formed with said pattern.

30. An imaging display system comprising:

a substrate;

on one surface of the substrate, a molecular light valve layer, having bimodal properties rendering each molecule either substantially transparent or substantially opaque;

superposing the light valve layer an imaging layer having a color filter layer having a pattern of pixels further comprising subpixel regions of primary color filters;

a mechanism for addressing the regions by applying selective electrical fields for switching selected molecules such that images are formed with said pattern.

31. The display system set forth in claim 30 embodied in electronic paper, electronic reading materials, computer displays, television and high definition television, projectors and projection screens, electronic billboards, electronic wallpaper, windowglass displays, multi-spectral optical communication light modulators, electronic pictures and photographs, or electronic fabrics.