DISPLAY DEVICE CONTAINING MINUTE DROPLETS OF CHOLESTERIC LIQUID CRYSTALS IN A SUBSTANTIALLY CONTINUOUS POLYMERIC MATRIX

• US 3,600,060 A
• Filed: 02/23/1968
• Issued: 08/17/1971
• Est. Priority Date: 02/23/1968
• Status: Expired due to Term

• Current Assignee: Donald Churchill, James V. Cartmell
• Original Assignee: Donald Churchill, James V. Cartmell
• Inventors: Churchill, Donald, Cartmell, James V.
• Primary Examiner(s): Lake, Roy
• Assistant Examiner(s): Lafranchi, V.
• Application Number:
  US04/707,706
• Time in Patent Office: 1,271 Days
• Field of Search: 313/108 315/246 350/160 23/23LC 252/301.2 250/71,83.3,43.5
• US Class Current: 349/21
• CPC Class Codes: B41M 5/281 using liquid crystals only
• CPC Class Codes: C09K 19/544 as dispersing or encapsulating medium around the liquid crystal
• CPC Class Codes: G02F 1/1333 Constructional arrangements; Manufacturing methodsG02F1/135, G02F1/136 take precedence
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G09G 3/001 using specific devices not provided for in groups G09G3/02 - G09G3/36, e.g. using an intermediate record carrier such as a film slide; Projection systems; Display of non-alphanumerical information, solely or in combination with alphanumerical information, e.g. digital display on projected diapositive as background slide projectors per se G03B23/00 = 42 HP
• CPC Class Codes: H01J 29/10 Screens on or from which an image or pattern is formed, picked up, converted or stored
• CPC Class Codes: H01J 29/14 acting by discoloration, e.g. halide screen
• CPC Class Codes: Y10T 428/2987 Addition polymer from unsaturated monomers only

Abstract

This disclosure is directed to articles of manufacture, chiefly display devices, containing minute '"'"''"'"''"'"''"'"'naked'"'"''"'"''"'"''"'"' droplets or inclusions of cholesteric liquid crystal material in a substantially continuous polymeric matrix, said liquid crystal material changing color or shade of color not only upon application of an electric potential but also upon removal of the field. The image produced has a comparable outline to that of the path of the electric field. Three chromatic states are evident, the normal color (before the electric potential is applied), the color given off when the electric field is applied, and the color observed when the electric field is removed. All three chromatic states are readily discernible from one another. The polymer matrix protects the cholesteric liquid crystal droplets from aging and enhances electric field behavior because the third chromatic state (electric potential removed) has a greater longevity with the matrix-bound material versus unprotected material of identical composition but no polymeric matrix. Other advantages are also discussed.

Claims

1. An article of manufacture comprising a pair of spaced electrodes and located there between a cholesteric liquid crystalline member chromatically responsive to the electric field imposed due to said electrodes and comprised of a plurality of individual minute, naked droplets of cholesteric liquid crystal material confined in a substantially continuous polymeric matrix.

2. An article as in claim 1 wherein said electric field ranges from about 10,000 to about 1,000,000 volts per centimeter of thickness of said cholesteric liquid crystalline member.

3. An article as in claim 1 wherein one of said electrodes is substantially transparent.

4. An article as in claim 3 wherein includes an opaque contrasting background located behind said cholesteric liquid crystalline member.

5. An article as in claim 4 which includes a substantially transparent protective covering for said substantially transparent electrode.

6. An article as in claim 4 which includes a protective polymer film located intermediate said opaque contrasting background and said cholesteric liquid crystalline member.

7. An article as in claim 6 wherein said droplets are uniformly distributed within said polymeric matrix.

8. An article as in claim 6 wherein said droplets have average diameters ranging from about 1 to about 30 microns.

9. An article as in claim 6 wherein said cholesteric liquid crystalline member contains from about 30 to about 95 weight percent cholesteric liquid crystal material, based on the total weight of said matrix and liquid crystal material.

10. An article as in claim 6 wherein the average thickness of said liquid crystalline member ranges from about 0.001 to about 0.05 centimeters.

11. A display device for chromatically representing a configuration established by an electric field comprising a first electrode and a second electrode spaced therefrom, said first electrode being closer to a viewing agency than said second electrode, and a cholesteric liquid crystalline member located between said electrodes and chromatically responsive to said electric field said member comprised of a profusion of individual, minute, naked droplets of cholesteric liquid crystal material confined in a substantially continuous, solid polymeric matrix.

12. A display device as in claim 11 wherein said first electrode is substantially transparent.

13. A display device as in claim 12 wherein said substantially transparent first electrode has a substantially transparent protective covering.

14. A display device as in claim 11 which includes an opaque contrasting background located between said cholesteric liquid crystalline member and said second electrode.

15. A display device as in claim 14 which includes a protective polymer layer located intermediate said opaque contrasting background said cholesteric liquid crystalline member.

16. A display device having polychromatic capability for chromatically representing an optionally comparatively permanent yet thermally erasable configuration established by an electric field in optional conjunction with an independently operable yet thermally erasable transient, thermally operable, separate display means, said device comprising a transparent support;

support;

a transparent electroconductive coating on said support;

conductive electrodes in contact with said coating and operatively connected by leads to an electric field source;

an insulator film having a cholesteric liquid crystal member in intimate proximity to said film and said coating, said cholesteric liquid crystal member comprised of a profusion of individual naked droplets of cholesteric liquid crystal material, chromatically responsive to an electric field, confined in a substantially continuous solid polymeric matrix; and

at least one electrically conductive resistive element in thermally responsive association with said cholesteric liquid crystal member, each said resistive element having a separate pair of conductive leads connected to a current source operable independently from said electric field source and wherein said cholesteric liquid crystal member is chromatically responsive to both an electric field and thermally energy applied thereto.

17. A display device as in claim 16 wherein said insulator film is opaque.