Liquid crystal display device having touch screen function and method of fabricating the same

• US 20050094038A1
• Filed: 06/11/2004
• Published: 05/05/2005
• Est. Priority Date: 11/04/2003
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Group)
• Original Assignee: Samsung Electronics Co. Ltd. (Samsung Group)
• Inventors: Choi, Joon-hoo, Joo, In-soo
• Granted Patent: US 7,280,167 B2
• Time in Patent Office: Days
• US Class Current: 349/12
• CPC Class Codes: G02F 1/133371 Cells with varying thickness of the liquid crystal layer
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/13624 having more than one switching element per pixel
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0447 Position sensing using the local deformation of sensor cells

Abstract

The present invention relates to an LCD device having a touch screen function. The LCD device of the present invention includes a plurality of gate lines, a plurality of data lines intersecting the gate lines, and a plurality of signal lines that are insulated from and juxtaposed with the data lines. First to third switching elements are formed in each of a plurality of pixel regions in the form of a matrix, which are surrounded by the gate lines and the data lines. Here, a gate electrode of the first switching element is connected to a gate line Gn, a source electrode thereof is connected to the data line, and a drain electrode thereof is connected to a pixel electrode. Further, liquid crystal capacitance and storage capacitance are formed between the pixel electrode and a common electrode. At this time, the liquid crystal capacitance is changed due to variation in the liquid crystal cell gap. The second and third switching elements are designed to read variation in the liquid crystal capacitance. A source electrode of the second switching element is connected to the pixel electrode, a drain electrode thereof is connected to the signal line, and a gate electrode thereof is connected to a previous gate line Gn-1. Furthermore, a source electrode of the third switching element is connected to the data line, a drain electrode thereof is connected to the pixel electrode, and a gate electrode thereof is connected to a second previous gate line Gn-2. Each signal line is connected to each signal amplifier.

Claims

1. A liquid crystal display (LCD) device having a touch screen function, comprising:

a plurality of gate lines that transfer scan signals;

a plurality of data lines that intersect the gate lines;

a plurality of signal lines that are formed in parallel with the data lines;

two or more switching elements that are formed in each of a plurality of pixel regions in the form of a matrix, which are surrounded by the gate lines and the data lines; and

signal amplifiers that receive signals applied to the signal lines in response to the operation of the two or more switching elements.

2. The LCD device as claimed in claim 1, wherein three switching elements are formed in each pixel region, and wherein the first switching element among them is turned on to charge a relevant data voltage when a gate-on signal is applied to a relevant gate line,

the second switching element is turned on to charge a previous data voltage when the gate-on signal is applied to a previous gate line, and

the third switching element is turned on to apply the previous data voltage to the signal line when the gate-on signal is applied to a second previous gate line.

3. The LCD device as claimed in claim 1, wherein two switching elements are formed in each pixel region, and wherein the first switching element is turned on to charge a relevant data voltage when a gate-on signal is applied to a relevant gate line, and

the second switching element is turned on to apply the data voltage charged during a previous frame time to the signal line when the gate-on signal is applied to a previous gate line.

4. An LCD device having a touch screen function, comprising:

an insulating substrate;

a gate line formed on the insulating substrate;

a gate insulating film covered on the gate line;

a data line that intersects the gate line and defines a pixel region on the gate insulating film;

a signal line formed in parallel with the data line;

a first thin film transistor electrically connected to both the gate line and the data line;

a second thin film transistor electrically connected to both a previous gate line and the signal line;

a third thin film transistor electrically connected to a second previous gate line and the data line;

a protection film that covers the first to third thin film transistors, the data line and the signal line, and includes first to third contact holes through which each of drain electrodes of the first to third thin film transistors is exposed; and

a pixel electrode that is connected to the first to third drain electrodes through the first to third contact holes.

5. The LCD device as claimed in claim 4, wherein the third thin film transistor is formed in a previous pixel region, and the third drain electrode extends up to the relevant pixel region and is connected to the relevant pixel electrode through the third contact hole.

6. A method of fabricating an LCD device having a touch screen function, comprising the steps of:

forming gate wiring including a gate line and first to third gate electrodes on an insulating substrate;

forming a gate insulating film for covering the gate wiring;

forming first to third semiconductor patterns on the gate insulating film;

forming, on the gate insulating film, data wiring including a data line that intersects the gate line, first to third source electrodes and first to third drain electrodes that are electrically connected to the first to third semiconductor patterns, and a signal line that is connected to the second source electrode;

forming a protection film that covers the semiconductor patterns and the data wiring;

forming first to third contact holes, through which the first to third drain electrodes are exposed, in the protection film; and

forming a pixel electrode that is connected to the first to third drain electrodes through the first to third contact holes.

7. The method as claimed in claim 6, wherein the third drain electrode extends from a previous pixel region up to a relevant pixel region and is connected to a relevant pixel electrode though the third contact hole.

8. An LCD device having a touch screen function, comprising:

an insulating substrate;

a gate line formed on the insulating substrate;

a gate insulating film covered on the gate line;

a data line that intersects the gate line and defines a pixel region on the gate insulating film;

a signal line formed in parallel with the data line;

a first thin film transistor electrically connected to both the gate line and the data line;

a second thin film transistor electrically connected to both a previous gate line and the signal line;

a protection film that covers the first and second thin film transistors, the data line and the signal line, and includes first and second contact holes through which each of drain electrodes of the first and second thin film transistors is exposed; and

a pixel electrode that is connected to the first and second drain electrodes through the first and second contact holes.

9. A method of fabricating an LCD device having a touch screen function, comprising the steps of:

forming gate wiring including a gate line and first and second gate electrodes on an insulating substrate;

forming a gate insulating film for covering the gate wiring;

forming first and second semiconductor patterns on the gate insulating film;

forming, on the gate insulating film, data wiring including a data line that intersects the gate line, first and second source electrodes and first and second drain electrodes that are electrically connected to the first and second semiconductor patterns, and a signal line that is connected to the second source electrode;

forming a protection film that covers the semiconductor patterns and the data wiring;

forming first and second contact holes, through which the first and second drain electrodes are exposed, in the protection film; and

forming a pixel electrode that is connected to the first and second drain electrodes through the first and second contact holes.