Common Bus Design for a TFT-LCD Display

• US 20100123866A1
• Filed: 12/19/2008
• Published: 05/20/2010
• Est. Priority Date: 11/18/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Zhong, John Z., Chang, Shih Chang
• Granted Patent: US 8,144,295 B2
• Time in Patent Office: Days
• US Class Current: 349/141
• CPC Class Codes: G02F 1/134345 Subdivided pixels, e.g. for grey scale or redundancy
• CPC Class Codes: G02F 1/134372 for fringe field switching [FFS] where the common electrode is not patterned
• CPC Class Codes: G02F 1/136286 Wiring, e.g. gate line, drain line
• CPC Class Codes: G02F 2201/40 Arrangements for improving the aperture ratio

Abstract

Embodiments of the present invention provide for a FFS TFT LCD with a high refresh rate without limiting the aperture of individual pixels. More specifically, embodiments of the invention provide for the use of common bus lines to reduce the effective resistance of the common electrode and to therefore allow for higher refresh rates of the display. Furthermore, the common bus lines can be positioned in such a manner so that they do not further reduce the aperture of the display. More specifically, the common bus lines can be positioned above or below existing elements of the display that are already opaque. Thus, adding the common bus lines need not reduce the aperture. The above can be achieved by, for example, placing the common bus lines above or below existing non-transparent lines, such as gate lines or data lines.

Claims

1. A display including a substrate assembly, the substrate assembly comprising:

a transparent conducting common electrode;

a plurality of opaque display elements; and

a plurality of common bus lines made from a non-transparent conductor, the non-transparent conductor having a lower resistance than the transparent conducting common electrode, the common bus lines connected to the common electrode and positioned at a different layer in the substrate assembly than the opaque display elements such that the opaque display elements substantially overlap the common bus lines.

2. The display of claim 1, wherein the opaque display elements completely overlap the common bus lines.

3. The display of claim 1, wherein the common bus line is connected to the common electrode at multiple points.

4. The display of claim 1, wherein the common bus line shares a side with the common electrode.

5. The display of claim 1, wherein the plurality of opaque display elements are a plurality of conductive lines and individual ones of the plurality of conductive lines are associated with individual ones of the plurality of common bus lines, each conductive line substantially covering at least its associated common bus line, and each associated conductive line and common bus line running substantially in parallel.

6. The display of claim 5, wherein the plurality of conductive lines are a plurality of data lines.

7. The display of claim 5, wherein the plurality of conductive lines are a plurality of gate lines.

8. The display of claim 1, wherein the plurality of opaque display elements include transistors or portions thereof.

9. The display of claim 1, wherein the substrate assembly further includes a pixel electrode positioned in proximity to the common electrode, and a voltage between the pixel electrode and the common electrode determines a display functionality of a particular pixel.

10. The display of claim 9, wherein the pixel electrode is positioned above the common electrode and the pixel electrode has a comb-like shape.

11. The display of claim 9, wherein the common electrode is positioned above the pixel electrode and the common electrode has a comb like shape.

12. A mobile telephone comprising the display of claim 1.

13. A portable audio device comprising the display of claim 1.

14. A television set comprising the display of claim 1.

15. A display having a substrate assembly, the substrate assembly comprising:

a transparent conducting common electrode;

a plurality of opaque display elements; and

a plurality of common bus lines made from a non-transparent conductor, the non-transparent conductor having a lower resistance than the transparent conducting common electrode, the common bus lines connected to the common electrode and positioned at a different layer in the substrate assembly than the opaque display elements such that, despite the existence of the common bus lines, an aperture of the display can be maintained at any reference aperture that would have been possible in the absence of the plurality of common bus lines.

16. The display of claim 15, wherein the opaque display elements completely overlap the common bus lines.

17. The display of claim 15, wherein the plurality of opaque display elements are a plurality of conductive lines and individual ones of the plurality of conductive lines are associated with individual ones of the plurality of common bus lines, each conductive line substantially covering at least its associated common bus line, and each associated conductive line and common bus line running substantially in parallel.

18. A display having a substrate assembly, the substrate assembly comprising:

a transparent conducting common electrode;

a plurality of opaque display elements defining a black mask; and

a plurality of common bus lines made from a non-transparent conductor, the non-transparent conductor having a lower resistance than the transparent conducting common electrode, the common bus lines connected to the common electrode and positioned at a different layer in the substrate assembly than the opaque display elements such that the common bus lines are within the black mask.

19. The display of claim 18, wherein the plurality of display elements defining a black mask include one or more elements selected from the group consisting of:

data lines, gate lines and transistors.

20. The display of claim 18, wherein the common bus line is connected to the common electrode at multiple points.

21. A mobile telephone including a display having a substrate assembly, the substrate assembly comprising:

a transparent conducting common electrode;

a plurality of opaque display elements; and

a plurality of common bus lines made from a non-transparent conductor, the non-transparent conductor having a lower resistance than the transparent conducting common electrode, the common bus lines connected to the common electrode and positioned at a different layer in the substrate assembly than the opaque display elements such that the opaque display elements substantially overlap the common bus lines.

22. A portable audio device including a display having a substrate assembly, the substrate assembly comprising:

a transparent conducting common electrode;

a plurality of opaque display elements; and

a plurality of common bus lines made from a non-transparent conductor, the non-transparent conductor having a lower resistance than the transparent conducting common electrode, the common bus lines connected to the common electrode and positioned at a different layer in the substrate assembly than the opaque display elements such that the opaque display elements substantially overlap the common bus lines.

23. A method for producing a display including manufacturing a substrate assembly by:

forming a transparent conducting common electrode on a substrate;

forming a plurality of opaque display elements on the substrate;

forming on the substrate a plurality of common bus lines made from a non-transparent conductor, the non-transparent conductor having a lower resistance than the transparent conducting common electrode, by positioning the common bus lines at a different layer in the substrate assembly than the opaque display elements such that the opaque display elements substantially overlap the common bus lines, and connecting the common bus lines to the common electrode.

24. The method of claim 23, wherein the opaque display elements completely overlap the common bus lines.

25. The method of claim 23, further comprising connecting the common bus line to the common electrode at multiple points.

26. The method of claim 23, further comprising forming the common bus line next to the common electrode so that they share a side.

27. The method of claim 23, wherein the plurality of opaque display elements are a plurality of conductive lines and individual ones of the plurality of conductive lines are associated with individual ones of the plurality of common bus lines, each conductive line substantially covering at least its associated common bus line, and each associated pair of a conductive line and a common bus line running substantially in parallel.

28. The method of claim 27, wherein the plurality of conductive lines are a plurality of data lines.

29. The method of claim 27, wherein the plurality of conductive lines are a plurality of gate lines.

30. The method of claim 23, wherein forming the plurality of opaque display elements includes forming transistors or portions thereof.

31. The method of claim 23, further including forming on the substrate a pixel electrode positioned in proximity to the common electrode so that a voltage between the pixel electrode and the common electrode determines a display functionality of a particular pixel.

32. The method of claim 31, wherein the pixel electrode is positioned above the common electrode and the pixel electrode has a comb-like shape.

33. The method of claim 31, wherein the common electrode is positioned above the pixel electrode and the common electrode has a comb like shape.