Liquid crystal display device

• US 20070018943A1
• Filed: 07/21/2006
• Published: 01/25/2007
• Est. Priority Date: 07/22/2005
• Status: Active Grant

• Current Assignee: AEG Gesellschaft Fuer Moderne Informationssysteme Mbh
• Original Assignee: AEG Gesellschaft Fuer Moderne Informationssysteme Mbh
• Inventors: Bader, Otto, Bitter, Thomas, Bayrle, Reiner
• Granted Patent: US 7,911,439 B2
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/133562 on the viewer side
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/13476 in which at least one liquid crystal cell or layer assumes a scattering state

Abstract

A liquid crystal display with improved display characteristics is disclosed. An OLED element is used as backlighting device resulting in a very flat liquid crystal display with a backlighting device. At least the front OLED drive electrode is formed such that it is at least partly light-transmissive, so that light from the OLED can be incident on the LCD element. The combination of an LCD element having internal reflectors or internal scattering elements and an OLED backlighting yields a thin overall display element which can be illuminated by sunlight during daytime and which can be illuminated using the OLED backlighting. Both the LCD element and the OLED element or OLED backlighting may represent information. For example, the actual information can be displayed on the LCD element, while the OLED element, primarily functioning as a backlighting device, can additionally represent a logo.

Claims

1. Liquid crystal display comprising

a LCD element for displaying information, said LCD element comprises internal reflectors or internal scattering elements and front and back LCD drive electrodes between which a liquid crystal is embedded, and

a backlighting device for illuminating the LCD element from behind,

said backlighting device comprises a layered OLED element with a front OLED drive electrode facing the LCD element and with back OLED drive electrode facing away from the LCD element and with OLED material in between the front and back OLED drive electrodes.

5. Liquid crystal display comprising according to claim 1, 3 or 3, wherein said LCD element is a cholesteric multistable LCD element.

6. Liquid crystal display according to claim 1, 2 or 3, wherein at least said front OLED electrode is formed in multipartite fashion.

7. Liquid crystal display according to claim 1, 2 or 3, wherein said layered OLED element covers at least the active display area of said LCD element.

8. Liquid crystal display according to claim 1, 2 or 3, wherein at least one enhancement film is arranged between said OLED element and said LCD element.

9. Liquid crystal display according to claim 1, 2 or 3, wherein said LCD element is transparent or non-transparent in the switched-off state.

10. Liquid crystal display according to claim 1, 2 or 3, wherein said back drive electrode of the OLED element is formed such that it is reflective in the direction of said front OLED drive electrode.

11. Liquid crystal display according to claim 10, wherein said back drive electrode of the OLED element is diffusely reflective in the direction of said front OLED drive electrode.

12. Liquid crystal display according to claim 11, wherein said LCD element comprises a twisted nematic liquid crystal.

13. Liquid crystal display according to claim 11, wherein said LCD element is transflective.

14. Liquid crystal display according claim 1, 2 or 3, wherein a diffuser element is arranged between said OLED element and said LCD element.

15. Liquid crystal display according to claim 14, wherein said diffuser element is switchable between a transparent state and a diffuse state.

16. Liquid crystal display according to claim 15, wherein said switchable diffuser element is a PDLC element or an EASL element.

17. Liquid crystal display according to claim 16, wherein said back OLED drive electrode is light-absorbing.

18. Liquid crystal display according to claim 17, wherein a light-absorbing layer is provided on that side of the LCD element which faces the OLED element, outside the region of the internal reflectors or outside the region of said scattering elements.

19. Liquid crystal display according to claim 1, 2 or 3, wherein said OLED element is capable of displaying a specific pattern.

20. Liquid crystal display according to claim 1, 2 or 3, wherein said diffuser element is capable of displaying a specific pattern.

2. Liquid crystal display comprising

a LCD element for displaying information, said LCD element comprises internal reflectors or internal scattering elements and front and back LCD drive electrodes between which a liquid crystal is embedded, and

a backlighting device for illuminating the LCD element from behind,

said backlighting device comprises a layered OLED element with a front OLED drive electrode facing the LCD element and with back OLED drive electrode facing away from the LCD element and with OLED material in between the front and back OLED drive electrodes,

wherein said front OLED drive electrode is light-transmissive in the area of said internal reflectors or in the area of said scattering elements and light-absorbing elsewhere.

3. Liquid crystal display comprising

a LCD element for displaying information, said LCD element comprises internal reflectors or internal scattering elements and front and back LCD drive electrodes between which a liquid crystal is embedded, and

a backlighting device for illuminating the LCD element from behind,

said backlighting device comprises a layered OLED element with a front OLED drive electrode facing the LCD element and with back OLED drive electrode facing away from the LCD element and with OLED material in between the front and back OLED drive electrodes,

wherein said front OLED drive electrode is light-transmissive and is only provided in the area of said internal reflectors or in the area of said scattering elements.

4. Liquid crystal display according to claim 3, wherein said back OLED drive electrode is only provided in the area of said internal reflectors or in the area of said scattering elements.

21. Liquid crystal display comprising

a LCD element for displaying information, comprising front and back LCD drive electrodes between which a liquid crystal is embedded,

a backlighting device for illuminating the LCD element from behind,

said backlighting device comprises a layered OLED element with a front OLED drive electrode facing the LCD element and with back OLED drive electrode facing away from the LCD element and with OLED material in between the front and back OLED drive electrodes, and

a diffuser element arranged between said OLED element and said LCD element.

22. Liquid crystal display according to claim 21, wherein said diffuser element is switchable between a transparent state and a diffuse state.

23. Liquid crystal display according to claim 22, wherein said switchable diffuser element is a PDLC element or an EASL element.

24. Liquid crystal display according to claim 21, wherein said back OLED drive electrode is light-absorbing.