Method and display panel for displaying color image

• US 6,020,866 A
• Filed: 11/26/1996
• Issued: 02/01/2000
• Est. Priority Date: 10/17/1994
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Yamaguchi, Chiseki
• Primary Examiner(s): Chow, Dennis-Doon
• Application Number:
  US08/756,819
• Time in Patent Office: 1,162 Days
• Field of Search: 345/102, 345/106, 345/107, 345/86, 428/411.1, 428/692, 428/913, 428/195, 428/420, 367/68, 367/70, 313/504, 349/20, 349/104, 349/94, 349/187, 349/21, 349/23, 349/112, 359/288, 359/289
• US Class Current: 345/86
• CPC Class Codes: C09K 2323/06 Substrate layer characterised by chemical composition
• CPC Class Codes: G09F 9/37 being movable elements G09F9/302 takes precedence
• CPC Class Codes: G09F 9/375 the position of the elements being controlled by the application of a magnetic field
• CPC Class Codes: Y10S 428/913 Material designed to be responsive to temperature, light, moisture
• CPC Class Codes: Y10T 428/24802 Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]
• CPC Class Codes: Y10T 428/24893 including particulate material
• CPC Class Codes: Y10T 428/31504 Composite [nonstructural laminate]
• CPC Class Codes: Y10T 428/31536 Including interfacial reaction product of adjacent layers
• CPC Class Codes: Y10T 428/31801 Of wax or waxy material

Abstract

A color image is displayed by using a display panel with a color pattern layer which is formed on one side of a transparent substrate and has, for example, three separate sets of transparent pixel areas in red, green and blue colors which constitute a regularly repetitive pattern and a set of opaque band-like areas by which each pixel area is bordered. The display panel further comprises, usually on the opposite side of the substrate, either a thermal recording layer which exhibits reversible changes in transmittance with temperature or a magnetic recording layer which contains flaky particles of a ferromagnetic metal dispersed in a polymer and exhibits reversible changes in transmittance with orientations of the flaky particles. To display an image, the thermal recording layer is heated in areas opposite to selected pixel areas of the color pattern layer, or a magnetic field parallel to or perpendicular to the display panel is applied to the magnetic recording layer in areas opposite to selected pixel areas, and then the display panel is backlighted.

Claims

1. A method of displaying a color image on a display panel, the method comprising:

using a display panel having a transparent substrate, a color pattern layer which is formed on one side of the substrate and has a multiplicity of transparent pixel areas consisting of at least two separate sets of pixel areas in different colors which constitute a repetitive pattern and a set of repetitively arranged opaque areas by which each of the pixel areas is bordered, and a recording layer which is formed on the substrate to lie parallel to the color pattern layer and is formed of a recording material which exhibits reversible changes in transmittance by application of external stimulus;

selectively applying an external stimulus to the recording layer of the display panel to change the transmittance of the recording layer in areas opposite to selected pixel areas of the color pattern layer; and

backlighting the display from a selected side.

2. A method according to claim 1, wherein said recording material is a thermal recording material which exhibits reversible changes in transmittance with temperature, said external stimulus being heat.

3. A method according to claim 1, wherein said recording material is a magnetic recording material, said external stimulus being a magnetic field.

4. A method according to claim 3, wherein said magnetic recording material comprises flaky particles of a ferromagnetic metal dispersed in a transparent polymer, said magnetic field being in such a direction that said flaky particles in said areas are oriented in a direction selected from a first direction which is parallel to said substrate and a second direction which is perpendicular to said substrate.

5. A method of displaying a color image on a display panel, the method comprising:

using a display panel having a transparent substrate, a color pattern layer which is formed on one side of the substrate and has a multiplicity of transparent pixel areas consisting of at least two separate sets of pixel areas in different colors which constitute a repetitive pattern and a set of repetitively arranged opaque areas by which each of the pixel areas is bordered, and a thermal recording layer which is formed on the opposite side of the substrate and is formed of a thermal recording material which exhibits reversible changes in transmittance with temperature;

selectively heating the thermal recording layer to change the transmittance of the recording layer in areas opposite to selected pixel areas of the color pattern layer; and

backlighting the display panel from the side on which the color pattern layer exists.

6. A method according to claim 5, wherein said thermal recording material comprises a mixture of a fatty acid and a thermoplastic resin.

7. A method according to claim 5, wherein said thermal recording material comprises a polymer liquid crystal.

8. A method according to claim 5, wherein said thermal recording material comprises a polymer blend.

9. A method according to claim 5, wherein the color pattern layer has three separate sets of pixel areas which are in red, green and blue colors, respectively.

10. A method according to claim 5, wherein all the pixel areas are rectangular areas.

11. A method according to claim 5, wherein said opaque, areas are black areas.

12. A method of displaying a color image on a display panel, the method comprising:

using a display panel having a transparent substrate, a color pattern layer which is formed on one side of the substrate and has a multiplicity of transparent pixel areas consisting of at least two separate sets of pixel areas in different colors which constitute a repetitive pattern and a set of repetitively arranged opaque areas by which each of the pixel areas is bordered, and a magnetic recording layer which is formed on the substrate to lie parallel to the color pattern layer and is formed of a magnetic recording material comprising flaky particles of a ferromagnetic metal dispersed in a transparent polymer;

orienting said flaky particles in the magnetic recording layer in a first direction which is parallel to the substrate or in a second direction which is perpendicular to the substrate;

selectively applying a magnetic field to the magnetic recording layer to change the orientation of said flaky particles to one of said first and second directions in areas opposite to selected pixel areas of the color pattern layer; and

backlighting the display panel from the side on which the color pattern layer exists.

13. A method according to claim 12, wherein said flaky particles are confined in microcapsules of an organic material.

14. A method according to claim 12, wherein said color pattern layer and said magnetic recording layer are formed on the opposite sides of the substrate, respectively.

15. A method according to claim 12, wherein the color pattern layer has three separate sets of pixel areas which are in red, green and blue colors, respectively.

16. A method according to claim 12, wherein all the pixel areas are rectangular areas.

17. A method according to claim 12, wherein said opaque, areas are black areas.