Liquid crystal display device having a common voltage compensator

• US 10,372,257 B2
• Filed: 10/26/2015
• Issued: 08/06/2019
• Est. Priority Date: 12/22/2014
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Kim, Hoon Bae, Kim, Sun Yeop, Lee, Sung Yub, Kang, Seong Kyu
• Primary Examiner(s): Harris, Dorothy
• Application Number:
  US14/923,051
• Publication Number:
  US 20160180781A1
• Time in Patent Office: 1,380 Days
• Field of Search: None
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/134372 for fringe field switching [FFS] where the common electrode is not patterned
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/04184 Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: G09G 2310/0291 Details of output amplifiers or buffers arranged for use in a driving circuit
• CPC Class Codes: G09G 2330/06 Handling electromagnetic interferences [EMI], covering emitted as well as received electromagnetic radiation
• CPC Class Codes: G09G 3/3655 Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors

Abstract

A liquid crystal display device is disclosed, which may compensate for a common voltage by reflecting all of noises by which a plurality of common electrodes are affected. The liquid crystal display device comprises a liquid crystal display panel including a plurality of data lines, a plurality of gate lines crossing the data lines, and a plurality of pixels provided at crossing regions of the data lines and the gate lines and including pixel electrodes and common electrodes to which a common voltage is supplied, wherein a common electrode of the common electrodes is shared by two or more of the plurality of pixels. The liquid crystal display panel also includes a plurality of feedback lines that overlap the common electrodes, the plurality of feedback lines receiving a variation of the common voltage that is reflected by the common electrodes onto the plurality of feedback lines.

Claims

1. An in-cell type touch liquid crystal display device comprising:

an in-cell type touch liquid crystal display panel including;

a plurality of data lines that receive data voltages;

a plurality of gate lines that receive gate signals;

a plurality of pixels at crossing regions of the plurality of data lines and the plurality of gate lines, each of the plurality of pixels including one pixel electrode;

a plurality of common electrodes supplied with a common voltage, wherein each of the common electrodes is shared by some neighboring pixels, and the pixels are grouped by the common electrodes;

a plurality of common lines supplying the common voltage to the common electrodes, wherein one of the common lines is connected to one of the common electrodes; and

a plurality of feedback lines that overlap the common electrodes, the plurality of feedback lines receiving a variation of the common voltage that is reflected by the common electrodes onto the plurality of feedback lines, wherein each of the plurality of feedback lines is provided between two adjacent pixel electrodes and is parallel to adjacent common lines; and

a common voltage compensator that compensates the common voltage based on the variation of the common voltage that is reflected onto the plurality of feedback lines.

2. The in-cell type touch liquid crystal display device of claim 1, wherein each of the shared common electrodes are overlapped with pixel electrodes of the some of the plurality of pixels.

3. The in-cell type touch liquid crystal display device of claim 1, wherein the plurality of feedback lines cross the plurality of gate lines.

4. The in-cell type touch liquid crystal display device of claim 1, wherein the plurality of feedback lines are floating such that a voltage is not applied to the plurality of feedback lines.

5. The in-cell type touch liquid crystal display device of claim 4, wherein each of the plurality of feedback lines includes a first end and a second end, the first ends of the plurality of feedback lines are floating and the second ends of the plurality of feedback lines are connected together, and the variation of the common voltage is input to the common voltage compensator via the second ends of the plurality of feedback lines.

6. The in-cell type touch liquid crystal display device of claim 5, wherein the variation of the common voltage of the common electrodes is reflected in each of the feedback lines by a parasitic capacitance between the common electrodes and each of the feedback lines.

7. The in-cell type touch liquid crystal display device of claim 1, wherein one or more of the plurality of feedback lines is arranged between a pair of adjacent common lines.

8. The in-cell type touch liquid crystal display device of claim 7, wherein each common line is positioned between two adjacent pixel electrodes.

9. The in-cell type touch liquid crystal display device of claim 7, wherein each common electrode is coupled to a common line through a contact hole that exposes the common line.

10. The in-cell type touch liquid crystal display device of claim 7, further comprising:

a data driver that supplies the data voltages to the plurality of data lines during a display mode of the display device;

a gate driver that supplies the gate signals to the plurality of gate lines in a pre-determined order during the display mode of the display device; and

a touch driver that supplies the common voltage to the common lines during the display mode of the display device and supplies touch driving signals to the common lines during a touch mode of the display device, wherein the display mode is non-overlapping with the touch mode.

11. The in-cell type touch liquid crystal display device of claim 7, wherein the plurality of gate lines are provided in a first metal layer, the plurality of data lines are provided in a second metal layer on a gate insulating film that covers the first metal layer, the pixel electrodes are provided in a first transparent electrode layer on a planarization film that covers the second metal layer, the common lines and the plurality of feedback lines are provided in a third metal layer on a second passivation film that covers the first transparent electrode layer, and the common electrodes are provided in a second transparent electrode layer on an inter layer dielectric that covers the third metal layer.

12. The in-cell type touch liquid crystal display device of claim 7, wherein the common voltage compensator includes:

a first input terminal connected to the plurality of feedback lines, the first input terminal receiving the variation of the common voltage from the plurality of feedback lines;

a second input terminal connected to a reference common voltage;

a capacitor that supplies the variation of the common voltage received from the plurality of feedback lines to a first node of the common voltage compensator;

an inversion amplifier that outputs a compensated common voltage by inverting and amplifying the variation of the common voltage at the first node in accordance with the reference common voltage inputted to the second input terminal; and

an output terminal connected to the common lines, the output terminal outputting the compensated common voltage to the plurality of common lines.

13. The in-cell type touch liquid crystal display device of claim 1, wherein the plurality of feedback lines are a substantially same length.

14. The in-cell type touch liquid crystal display device of claim 1, wherein the variation of the common voltage is stored in a capacitance formed between the common electrodes and the plurality of feedback lines that overlap the common electrodes.