Liquid crystal display in which at least one pixel includes both a transmissive region and a reflective region

• US 6,195,140 B1
• Filed: 07/27/1998
• Issued: 02/27/2001
• Est. Priority Date: 07/28/1997
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Yoshimura, Yoji, Shimada, Takayuki, Kubo, Masumi, Ishii, Yutaka, Ban, Atsushi, Narutaki, Yozo, Katayama, Mikio, Nishiki, Hirohiko
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): CHOWDHURY, TARIFUR RASHID
• Application Number:
  US09/122,756
• Time in Patent Office: 946 Days
• Field of Search: 348/42, 348/44, 348/143, 348/147, 348/95, 348/111
• US Class Current: 349/44
• CPC Class Codes: G02F 1/133526 Lenses, e.g. microlenses or Fresnel lenses
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/133638 Waveplates, i.e. plates with a retardation value of lambda/n
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: G02F 1/136209 Light shielding layers, e.g. black matrix, incorporated in the active matrix substrate, e.g. structurally associated with the switching element
• CPC Class Codes: G02F 1/136227 Through-hole connection of the pixel electrode to the active element through an insulation layer
• CPC Class Codes: G02F 1/13712 the liquid crystal having negative dielectric anisotropy
• CPC Class Codes: G02F 1/13725 based on guest-host interaction G02F1/13762, G02F1/13737, take precedence

Abstract

A liquid crystal display device according to the present invention includes a first substrate, a second substrate, and a liquid crystal layer interposed between the first substrate and the second substrate. The first substrate includes: a plurality of gate lines; a plurality of source lines arranged to cross with the plurality of gate lines; a plurality of switching elements disposed in the vicinity of crossings of the plurality of gate lines and the plurality of source lines; and a plurality of pixel electrodes connected to the plurality of switching elements. The second substrate includes a counter electrode. A plurality of pixel regions are defined by the plurality of pixel electrodes, the counter electrode, and the liquid crystal layer interposed between the plurality of pixel electrodes and the counter electrode, and each of the plurality of pixel regions includes a reflection region and a transmission region.

Claims

1. A liquid crystal display device comprising a first substrate, a second substrate, and a liquid crystal layer interposed between the first substrate and the second substrate, a plurality of pixel regions being defined by respective electrodes for applying a voltage to the liquid crystal layer,

wherein each of the plurality of pixel regions includes a reflection region and a transmission region, and wherein light reflected in said reflection regions and light transmitted through said transmission regions are utilized in displaying an image;

wherein the first substrate includes a reflection electrode region corresponding to the reflection region and a transmission electrode region corresponding to the transmission region; and

wherein the reflection electrode region is higher than the transmission electrode region, forming a step on a surface of the first substrate, and thus a thickness of the liquid crystal layer in the reflection region is smaller than a thickness of the liquid crystal layer in the transmission region.

2. A liquid crystal display-device according to claim 1, wherein the occupation of an area of the reflection region in each of the pixel regions is in the range of about 10 to about 90%.

3. A liquid crystal display device comprising a first substrate, a second substrate, and a liquid crystal layer interposed between the first substrate and the second substrate,

wherein the first substrate includes:

a plurality of gate lines;

a plurality of source lines arranged to cross with the plurality of gate lines;

a plurality of switching elements disposed in the vicinity of crossings of the plurality of gate lines and the plurality of source lines; and

a plurality of pixel electrodes connected to the plurality of switching elements,

the second substrate includes a counter electrode,

a plurality of pixel regions are defined by the plurality of pixel electrodes, the counter electrode, and the liquid crystal layer interposed between the plurality of pixel electrodes and the counter electrode,

each of the plurality of pixel regions includes a reflection region and a transmission region, and wherein light reflected in said reflection regions and light transmitted through said transmission regions are utilized in displaying an image;

wherein the first substrate includes a reflection electrode region corresponding to the reflection region and a transmission electrode region corresponding to the transmission region; and

wherein the reflection electrode region is higher than the transmission electrode region, forming a step on a surface of the first substrate, and thus a thickness of the liquid crystal layer in the reflection region is smaller than a thickness of the liquid crystal layer in the transmission region.

4. A liquid crystal display device according to claim 3, wherein the thickness of the liquid crystal layer in the reflection region is about a half of the thickness of the liquid crystal layer in the transmission region.

5. A liquid crystal display device according to claim 3, wherein the occupation of an area of the reflection region in each of the pixel regions is in the range of about 10 to about 90%.

6. A liquid crystal display device according to claim 3, further comprising microlenses on a surface of the first substrate opposite to the surface facing the liquid crystal layer.

7. A liquid crystal display device according to claim 3, wherein each of the reflection electrode regions includes a metal layer and an interlayer insulating film formed under the metal layer.

8. A liquid crystal display device according to claim 7, wherein the metal layer has a continuous wave shape.

9. A liquid crystal display device according to claim 8, wherein a surface of the interlayer insulating layer is of a concave and convex shape.

10. A liquid crystal display device according to claim 7, wherein the interlayer insulating layer is formed of a photosensitive polymer resin film.

11. A liquid crystal display device according to claim 7, therein the interlayer insulating layer covers at least a portion of either the switching element, the plurality of gate lines, or the plurality of source lines.

12. A liquid crystal display device comprising:

a first substrate, a second substrate, and a liquid crystal layer interposed between the first substrate and the second substrate;

wherein the first substrate includes;

a plurality of gate lines;

a plurality of source lines arranged to cross with the plurality of gate lines;

a plurality of switching elements disposed in the vicinity of crossings of the plurality of gate lines and the plurality of source lines; and

a plurality of pixel electrodes connected to the plurality of switching elements;

the second substrate includes a counter electrode;

a plurality of pixel regions are defined by the plurality of pixel electrodes, the counter electrode, and the liquid crystal layer interposed between the plurality of pixel electrodes and the counter electrode;

each of the plurality of pixel regions includes a reflection region and a transmission region, and wherein light reflected in said reflection regions and light transmitted through said transmission regions are utilized in displaying an image;

wherein the first substrate includes a reflection electrode region corresponding to the reflection region and a transmission electrode region corresponding to the transmission region; and

wherein each of the pixel electrodes includes a reflection electrode in the reflection electrode region and a transmission electrode in the transmission electrode region.

13. A liquid crystal display device according to claim 12, wherein the reflection electrode and the transmission electrode are electrically connected to each other.

14. A liquid crystal display device according to claim 12, wherein the reflection electrodes are formed at the same level as the plurality of gate lines or the plurality of source lines.

15. A liquid crystal display device according to claim 14, wherein the reflection electrodes are formed at the same level as the plurality of gate lines, and

the reflection electrodes are electrically connected to the gate lines for the pixel electrodes adjacent to the reflection electrodes.

16. A liquid crystal display device according to claim 14, wherein the same signals applied to the counter electrode are applied to the reflection electrodes.

17. A liquid crystal display device according to claim 14, wherein the reflection electrodes are formed at the same level as the plurality of gate lines, and

the reflection electrodes form storage capacitors by overlapping drain electrodes of the switching elements or the transmission electrodes.

18. A liquid crystal display device according to claim 12, wherein the reflection electrode is formed of Al or an Al alloy.

19. A liquid crystal display device according to claim 18, wherein the transmission electrode is formed of ITO, and a metal layer interposes between the transmission electrode and the reflection electrode.

20. A liquid crystal display device comprising:

a first substrate, a second substrate, and a liquid crystal layer interposed between the first substrate and the second substrate;

wherein the first substrate includes;

a plurality of rate lines;

a plurality of source lines arranged to cross with the plurality of gate lines;

a plurality of switching elements disposed in the vicinity of crossings of the plurality of gate lines and the plurality of source lines, and a plurality of pixel electrodes connected to the plurality of switching elements;

the second substrate includes a counter electrode;

a plurality of pixel regions are defined by the plurality of pixel electrodes, the counter electrode, and the liquid crystal layer interposed between the plurality of pixel electrodes and the counter electrode;

each of the plurality of pixel regions includes a reflection region and a transmission region, and wherein light reflected in said reflection regions and light transmitted through said transmission regions are utilized in displaying an image;

wherein the first substrate includes a reflection electrode region corresponding to the reflection region and a transmission electrode region corresponding to the transmission region; and

wherein each of the pixel electrodes comprises a transmission electrode, and the reflection region includes the transmission electrode and a reflection layer isolated from the transmission electrode.

21. A liquid crystal display device comprising:

a first substrate, a second substrate, and a liquid crystal layer interposed between the first substrate and the second substrate;

wherein the first substrate includes;

a plurality of gate lines;

a plurality of source lines arranged to cross with the plurality of gate lines;

a plurality of switching elements disposed in the vicinity of crossings of the plurality of gate lines and the plurality of source lines; and

a plurality of pixel electrodes connected to the plurality of switching elements;

the second substrate includes a counter electrode;

a plurality of pixel regions are defined by the plurality of pixel electrodes, the counter electrode, and the liquid crystal layer interposed between the plurality of pixel electrodes and the counter electrode;

each of the plurality of pixel regions includes a reflection region and a transmission region, and wherein light reflected in said reflection regions and light transmitted through said transmission regions are utilized in displaying an image;

wherein the first substrate includes a reflection electrode region corresponding to the reflection region and a transmission electrode region corresponding to the transmission region; and

wherein the reflection electrode regions overlap at least a portion of the plurality of gate lines, the plurality of source lines, and the plurality of switching elements.

22. A liquid crystal display device comprising:

a first substrate, a second substrate, and a liquid crystal layer interposed between the first substrate and the second substrate;

wherein the first substrate includes;

a plurality of gate lines;

a plurality of source lines arranged to cross with the plurality of gate lines;

a plurality of switching elements disposed in the vicinity of crossings of the plurality of gate lines and the plurality of source lines; and

a plurality of pixel electrodes connected to the plurality of switching elements;

the second substrate includes a counter electrode;

a plurality of pixel regions are defined by the plurality of pixel electrodes, the counter electrode, and the liquid crystal layer interposed between the plurality of pixel electrodes and the counter electrode;

each of the plurality of pixel regions includes a reflection region and a transmission region, and wherein light reflected in said reflection regions and light transmitted through said transmission regions are utilized in displaying an image;

wherein the first substrate includes a reflection electrode region corresponding to the reflection region and a transmission electrode region corresponding to the transmission region; and

wherein at least either of the reflection electrode regions and the transmission electrode regions have a layer formed of the same material as a material for the plurality of gate lines or the plurality of source lines.

23. A liquid crystal display device comprising:

a first substrate, a second substrate, and a liquid crystal layer interposed between the first substrate and the second substrate;

wherein the first substrate includes;

a plurality of gate lines;

a plurality of source lines arranged to cross with the plurality of gate lines;

a plurality of switching elements disposed in the vicinity of crossings of the plurality of gate lines and the plurality of source lines; and

a plurality of pixel electrodes connected to the plurality of switching elements;

the second substrate includes a counter electrode;

a plurality of pixel regions are defined by the plurality of pixel electrodes, the counter electrode, and the liquid crystal layer interposed between the plurality of pixel electrodes and the counter electrode;

each of the plurality of pixel regions includes a reflection region and a transmission region, and wherein light reflected in said reflection regions and light transmitted through said transmission regions are utilized in displaying an image;

wherein the first substrate includes a reflection electrode region corresponding to the reflection region and a transmission electrode region corresponding to the transmission region; and

wherein the first substrate further includes storage capacitor electrodes for forming storage capacitors with the pixel electrodes via an insulating film,

wherein the reflection electrode regions overlap the storage capacitor electrodes.

24. A method for fabricating a liquid crystal display device comprising a first substrate, a second substrate, and a liquid crystal layer interposed between the first substrate and the second substrate, the first substrate including:

a plurality of gate lines;

a plurality of source lines arranged to cross with the plurality of gate lines;

a plurality of switching elements disposed in the vicinity of crossings of the plurality of gate lines and the plurality of source lines; and

a plurality of pixel electrodes connected to the plurality of switching elements, the second substrate including a counter electrode, a plurality of pixel regions are defined by the plurality of pixel electrodes, the counter electrode, and the liquid crystal layer interposed between the plurality of pixel electrodes and the counter electrode, each of the plurality of pixel regions including a reflection region and a transmission region, the method comprising the steps of;

forming transmission electrode regions using a material having a high light transmittance on the first substrate;

forming photosensitive polymer resin layers; and

forming reflection layers made of a material having a high reflectance on the polymer resin layers in a manner such that both light reflected by the reflection layers in reflection regions and light transmitted through transmission regions are utilized in displaying an image.

25. A method according to claim 24, wherein the photosensitive polymer resin layers have a plurality of concave and convex portions.

26. A method for fabricating a liquid crystal display device comprising a first substrate, a second substrate, and a liquid crystal layer interposed between the first substrate and the second substrate, the first substrate including:

a plurality of gate lines;

a plurality of source lines arranged to cross with the plurality of gate lines;

a plurality of switching elements disposed in the vicinity of crossings of the plurality of gate lines and the plurality of source lines; and

a plurality of pixel electrodes connected to the plurality of switching elements, the second substrate including a counter electrode, a plurality of pixel regions are defined by the plurality of pixel electrodes, the counter electrode, and the liquid crystal layer interposed between the plurality of pixel electrodes and the counter electrode, each of the plurality of pixel regions including a reflection region and a transmission region, the method comprising the steps of;

forming transmission electrode regions using a material having a high light transmittance on the first substrate;

forming protection films on the transmission electrode regions; and

forming layers having a high reflectance on portions of the protection films to form the reflection electrode regions in a manner such that both light reflected by the layers of high reflectance in reflection regions and light transmitted through transmission regions are utilized in displaying an image.

27. A method according to claim 26, wherein the transmission electrode regions are formed at the same level as the plurality of source lines.

28. A liquid crystal display device comprising:

a first substrate;

a second substrate;

a liquid crystal layer interposed between the first substrate and the second substrate;

a plurality of pixel regions being defined by respective pairs of electrodes for applying a voltage to the liquid crystal layer;

wherein each of the plurality of pixel regions includes a reflection region and a transmission region; and

wherein a plurality of the pixel regions include a transmissive pixel electrode, and a reflective pixel electrode electrically isolated from the transmissive pixel electrode.

29. A liquid crystal display device comprising:

a first substrate;

a second substrate;

a liquid crystal layer interposed between the first substrate and the second substrate;

a plurality of pixel regions being defined by respective pairs of electrodes for applying a voltage to the liquid crystal layer;

wherein each of the plurality of pixel regions includes a reflection region and a transmission region; and

in at least one of said plurality of pixel regions, a reflection electrode of the reflection region overlaps at least a portion of first and second address lines which are in electrical communication with a switching element for the corresponding pixel region.

30. A liquid crystal display device comprising:

a first substrate;

a second substrate;

a liquid crystal layer interposed between the first substrate and the second substrate;

a plurality of pixel regions being defined by respective pairs of electrodes for applying a voltage to the liquid crystal layer;

wherein each of the plurality of pixel regions includes a reflection region and a transmission region; and

wherein said transmission regions each include a substantially transparent thin film pixel electrode and said reflection regions each include a reflective thin film pixel electrode.

31. A liquid crystal display device comprising:

a first substrate;

a second substrate;

a liquid crystal layer interposed between the first substrate and the second substrate;

a plurality of pixel regions being defined by respective pairs of electrodes for applying a voltage to the liquid crystal layer;

wherein each of the plurality of pixel regions includes a reflection region and a transmission region; and

wherein reflection electrodes of the reflective regions are formed at the same level as a plurality of address lines.

32. A liquid crystal display device comprising:

a first substrate;

a second substrate;

a liquid crystal layer interposed between the first substrate and the second substrate;

a plurality of pixel regions being defined by respective pairs of electrodes for applying a voltage to the liquid crystal layer;

wherein each of the plurality of pixel regions includes a reflection region and a transmission region; and

wherein at least one pixel region a reflection electrode forms a storage capacitor by overlapping a drain electrode of a switching element.

33. A liquid crystal display device comprising:

a first substrate;

a second substrate;

a liquid crystal layer interposed between the first substrate and the second substrate;

a plurality of pixel regions being defined by respective pairs of electrodes for applying a voltage to the liquid crystal layer;

wherein each of the plurality of pixel regions includes a reflection region and a transmission region provided in a manner such that an area of the reflection region is at least about 10% of the total area of the corresponding pixel region in at least one of said plurality of pixel regions.

34. A liquid crystal display device comprising:

a first substrate;

a second substrate;

a liquid crystal layer interposed between the first substrate and the second substrate;

a plurality of pixel regions being defined by respective pairs of electrodes for applying a voltage to the liquid crystal layer;

wherein each of the plurality of pixel regions includes a reflection region and a transmission region; and

in at least one pixel region the liquid crystal layer is substantially thicker in the transmission region than in the reflection region so that paths of respective light beams in each of these two regions are approximately equal to one another during operation of the display.