Liquid crystal display with identifiers

• US 9,851,612 B2
• Filed: 04/02/2014
• Issued: 12/26/2017
• Est. Priority Date: 04/02/2014
• Status: Active Grant

• Current Assignee: Kent Displays Incorporated
• Original Assignee: Kent Displays Incorporated
• Inventors: Davis, Don, Nicholson, Forrest
• Primary Examiner(s): DAVISON, ANGELA K
• Application Number:
  US14/243,432
• Publication Number:
  US 20150286085A1
• Time in Patent Office: 1,364 Days
• Field of Search: 349 12, 349185, 349104, 359 3, 359350, 359356, 359361, 359436, 428 13, 428 131, 428187, 4283213, 428327, 4283084
• CPC Class Codes: G02F 1/133374 for displaying permanent signs or marks
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/13718 based on a change of the texture state of a cholesteric liquid crystal
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: H01L 2223/544 Marks applied to semiconductor devices or parts

Abstract

A liquid crystal display with an identifier such as a watermark, serial number, logo or other graphic design, is disclosed. The identifiers can be read electronically or with the human eye. Methods are described for fabricating identifiers on cholesteric writing tablets in particular, with varying shades of gray and hence different degrees of visibility. The identifiers are permanent and not erased when a liquid crystal image on the display is erased.

Claims

1. A liquid crystal display comprising:

an upper substrate that is flexible and comprised of polymeric material;

a liquid crystal layer disposed below said upper substrate and comprising cholesteric liquid crystal material dispersed in polymer that is adapted to allow localized flow of said liquid crystal material caused by writing pressure on said upper substrate that forms an image in a display area by changing reflectance of said cholesteric liquid crystal material where said writing pressure is applied, said liquid crystal layer including upper and lower sides extending parallel to said upper substrate;

electrically conductive layers disposed adjacent to and parallel with said upper and lower sides of said liquid crystal layer;

a lower transparent substrate disposed below said liquid crystal layer, wherein a lower one of the electrically conductive layers is disposed on an upper surface of said lower transparent substrate;

a light absorbing back layer that absorbs light passing through said upper substrate and said liquid crystal layer, wherein said light absorbing back layer comprises a semitransparent ink disposed on said lower transparent substrate;

electronic circuitry for applying a voltage to said electrically conductive layers that erases said image; and

an identifier located on a component of said display in the display area, said component being selected from the group consisting of;

said upper substrate, a layer disposed on or near said upper substrate, said light absorbing back layer and combinations thereof.

2. The liquid crystal display of claim 1 including electronic circuitry that is in electrical contact with said electrically conductive layers and applies a voltage that erases the image.

3. The liquid crystal display of claim 2 wherein said component is said light absorbing back layer that includes different depths of material removed to form said identifier so as to produce a gray scale image on said display that is not erased by said electronic circuitry.

4. The liquid crystal display of claim 3 wherein said light absorbing back layer has recessed lines, spots or regions formed therein that form said identifier, comprising a coating in said recessed lines, spots or regions of said light absorbing back layer.

5. The liquid crystal display of claim 4 wherein said coating is selected to reflect light of a predetermined color.

6. The liquid crystal display of claim 2 wherein said identifier is not coupled to said electronic circuitry.

7. The liquid crystal display of claim 1 wherein said component is said upper substrate that includes a portion of material removed to form said identifier.

8. The liquid crystal display of claim 1 comprising at least two stacked said liquid crystal layers each sandwiched between two electrically conductive layers, wherein each of said liquid crystal layers reflects light of a different color than the other said liquid crystal layers.

9. The liquid crystal display of claim 8 which is an electronic skin.

10. The liquid crystal display of claim 8 which is a passive or active matrix display including patterned said electrically conductive layers and electronic drive circuitry that is in electrical contact with said electrically conductive layers and applies a voltage that changes reflectivity of said liquid crystal material in said liquid crystal layers so as to form an image on said display and erases an image on said display.

11. The liquid crystal display of claim 1 which is a passive or active matrix display including patterned said electrically conductive layers and electronic drive circuitry that is in electrical contact with said electrically conductive layers and applies a voltage that changes reflectivity of said liquid crystal material so as to form an image on said display and erases an image on said display.

12. The liquid crystal display of claim 1 wherein said identifier is selected from the group consisting of:

a watermark;

a digital watermark;

a graphic design;

a bar code, an identification numeral, an identification code, a dot pattern and combinations thereof.

13. An electronic device including said liquid crystal display of claim 1, wherein said electronic device is selected from the group consisting of:

a cell phone, a smart phone, a tablet, a laptop, a radio, a desktop monitor, an mp3player, an eReader, a toy, a television, motor vehicle instrument or accessory, electronic skin and combinations thereof.

14. A liquid crystal display comprising:

a flexible transparent polymeric layer forming a writing surface;

a liquid crystal layer comprising cholesteric liquid crystal material dispersed in polymer that is adapted to allow localized flow of said liquidcrystal material caused by writing pressure on said writing surface that forms an image in a display area by changing reflectance of said cholesteric liquid crystal material where said writing pressure is applied, said liquid crystal layer including upper and lower sides extending parallel to said writing surface;

electrically conductive layers disposed adjacent to and parallel with said upper and lower sides of said liquid crystal layer;

a lower substrate disposed below said liquid crystal layer and including a lower one of the electrically conductive layers disposed on an upper surface of said lower substrate;

a light absorbing back layer that absorbs light passing through said writing surface and said liquid crystal layer, wherein said light absorbing back layer comprises an opaque ink or a semitransparent ink and is disposed below said lower substrate;

electronic circuitry for applying a voltage to said electrically conductive layers that erases said image; and

an identifier disposed in the display area and below said liquid crystal layer,

wherein said identifier is viewed through said flexible transparent polymer layer in the display area.

15. The liquid crystal display of claim 14 wherein said identifier comprises recessed lines, spots or regions.

16. The liquid crystal display of claim 14 wherein said identifier is selected from the group consisting of:

a watermark;

a digital watermark;

a graphic design;

a bar code, an identification numeral, an identification code, a dot pattern and combinations thereof.

17. A liquid crystal display comprising:

an upper substrate that is transparent;

a liquid crystal layer including liquid crystal material disposed near said upper substrate, said liquid crystal layer including upper and lower sides extending parallel to said upper substrate;

electrically conductive layers disposed adjacent to and parallel with said upper and lower sides of said liquid crystal layer;

a light absorbing back layer positioned so as to absorb light passing through said upper substrate and said liquid crystal layer, said light absorbing back layer being located under said liquid crystal layer and under a lower one of said electrically conductive layers;

wherein an image is formed in a display area by changing a reflective state of the liquid crystal material that contrasts with said light absorbing back layer and said image can be erased;

an identifier located on a component of said display in the display area;

wherein said identifier is viewed on said liquid crystal display in the display area when the image is formed and after the image is erased;

electronic circuitry that is in electrical contact with said electrically conductive layers and applies a voltage that erases the image;

wherein said component is said light absorbing back layer that includes different depths of material removed to form said identifier so as to produce a gray scale image on said display that is not erased by said electronic circuitry;

wherein said light absorbing back layer has recessed lines, spots or regions formed therein that form said identifier, comprising a coating in said recessed lines, spots or regions of said light absorbing back layer; and

wherein said coating reflects infrared light with a different reflectivity than the light absorbing back layer and enables said identifier to be hidden except when viewed in infrared light.

18. A liquid crystal display comprising:

an upper substrate that is transparent;

a liquid crystal layer including liquid crystal material disposed near said upper substrate, said liquid crystal layer including upper and lower sides extending parallel to said upper substrate;

electrically conductive layers disposed adjacent to and parallel with said upper and lower sides of said liquid crystal layer;

a light absorbing back layer positioned so as to absorb light passing through said upper substrate and said liquid crystal layer, said light absorbing back layer being located under said liquid crystal layer and under a lower one of said electrically conductive layers;

wherein an image is formed in a display area by changing a reflective state of the liquid crystalmaterial that contrasts with said light absorbing back layer and said image can be erased;

an identifier located on a component of said display in the display area;

wherein said identifier is viewed on said liquid crystal display in the display area when the image is formed and after the image is erased;

electronic circuitry that is in electrical contact with said electrically conductive layers and applies a voltage that erases the image;

wherein said component is said light absorbing back layer that includes different depths of material removed to form said identifier so as to produce a gray scale image on said display that is not erased by said electronic circuitry;

wherein said light absorbing back layer has recessed lines, spots or regions formed therein that form said identifier, comprising a coating in said recessed lines, spots or regions of said light absorbing back layer; and

wherein said coating fluoresces visible light when activated by ultraviolet light and enables said identifier to be hidden except when ultraviolet light is applied to said coating.