Liquid crystal display device including switching element with floating terminal

Patent metadata

Field	Value
Publication number	US-2016291383-A1
Application number	US-201514878058-A
Country	US
Kind code	A1
Filing date	Oct 8, 2015
Priority date	Mar 31, 2015
Publication date	Oct 6, 2016
Grant date	—

Abstract

A liquid crystal display device includes: a first substrate for which a single pixel includes: first, second and third thin film transistors on the first substrate; a pixel electrode including a first subpixel electrode and a second subpixel electrode which are connected to the first thin film transistor and the second thin film transistor, respectively; and a divided reference voltage line connected to the third thin film transistor; a second substrate facing the first substrate; a common electrode on the second substrate; and a liquid crystal layer between the pixel electrode and the common electrode and including liquid crystal molecules. The third thin film transistor includes an electrically floating gate electrode, a source electrode defined by an extended portion of a terminal of the second thin film transistor, and a drain electrode defined by an extended portion of the divided reference voltage line.

First claim

What is claimed is:

1 . A liquid crystal display device, comprising:
a first substrate for which a single pixel includes:
a first thin film transistor, a second thin film transistor and a third thin film transistor on the first substrate;
a pixel electrode including a first subpixel electrode and a second subpixel electrode which are connected to the first thin film transistor and the second thin film transistor, respectively; and
a divided reference voltage line connected to the third thin film transistor;
a second substrate facing the first substrate; a common electrode on the second substrate; and a liquid crystal layer between the pixel electrode and the common electrode, the liquid crystal layer including liquid crystal molecules, wherein the third thin film transistor includes:
an electrically floating gate electrode,
a source electrode defined by an extended portion of a terminal of the second thin film transistor, and
a drain electrode defined by an extended portion of the divided reference voltage line.

2 . The liquid crystal display device of claim 1 , wherein:
the electrically floating gate electrode and the drain electrode defined by the extended portion of the divided reference voltage line form a first capacitor, and the electrically floating gate electrode and the source electrode defined by the extended portion of the terminal of the second thin film transistor form a second capacitor.

3 . The liquid crystal display device of claim 1 , further comprising:
a gate line and a data line on the first substrate and insulatively crossing each other, wherein the first thin film transistor and the second thin film transistor are connected to the gate line and the data line on the first substrate and insulatively crossing each other.

4 . The liquid crystal display device of claim 3 , wherein:
the electrically floating gate electrode of the third thin film transistor is in a same layer as the gate line, the electrically floating gate electrode in the same layer as the gate line being separated from the gate line.

5 . The liquid crystal display device of claim 3 , wherein:
the data line and the divided reference voltage line are in a same layer as each other.

6 . The liquid crystal display device of claim 3 , wherein:
the data line applies a same voltage to the first thin film transistor and to the second thin film transistor, the voltage applied to the second thin film transistor is divided through the third thin film transistor including the electrically floating gate electrode to define a divided reference voltage less than the voltage applied to the second thin film transistor, and the drain electrode defined by the extended portion of the divided reference voltage line receives the divided reference voltage which is less than the voltage applied to the second thin film transistor.

7 . The liquid crystal display device of claim 3 , wherein:
the single pixel further includes a first liquid crystal capacitor defined therein, and the first thin film transistor includes:
a first gate electrode defined by a first extended portion of the gate line,
a first source electrode defined by a first extended portion of the data line, and
a first drain electrode in a same layer as the first source electrode, the first drain electrode separated from the first source electrode,
wherein the first thin film transistor is connected to the first liquid crystal capacitor.

8 . The liquid crystal display device of claim 7 , wherein:
the single pixel further includes a second liquid crystal capacitor defined therein, and the second thin film transistor includes:
a second gate electrode defined by a second extended portion of the gate line of which the first extended portion thereof defines the first gate electrode,
a second source electrode defined by a second extended portion of the data line of which the first extended portion thereof defines the first source electrode, and
a second drain electrode in a same layer as the second source electrode, the second drain electrode separated from the second source electrode, and
wherein the second thin film transistor is connected to the second liquid crystal capacitor.

9 . The liquid crystal display device of claim 7 , wherein:
each of the first subpixel electrode and the second subpixel electrode includes: a cross stem, and a plurality of minute branches extended in an oblique direction from the cross stem.

10 . The liquid crystal display device of claim 9 , wherein:
the first drain electrode of the first thin film transistor overlaps the cross stem of the first subpixel electrode.

11 . The liquid crystal display device of claim 9 , wherein:
the first subpixel electrode and the first thin film transistor are connected to each other at a cross point of the cross stem.

12 . The liquid crystal display device of claim 3 , further comprising:
a light blocking member on the second substrate, the light blocking member overlapping the first to third thin film transistors to have a length in an extending direction of the gate line and a width in a direction perpendicular to the length thereof.

13 . The liquid crystal display device of claim 12 , wherein:
the width of the light blocking member is approximately 40 micrometers to approximately 70 micrometers.

14 . The liquid crystal display device of claim 3 , wherein:
each of the first and second thin film transistors is connected to a single gate line and a single data line which insulatively cross each other, and the second thin film transistor connected to the single gate line and the single data line which insulatively cross each other includes:
a second gate electrode defined by an extended portion of the single gate line,
a second source electrode defined by an extended portion of the single data line, and
a second drain electrode in a same layer as the second source electrode, the second drain electrode separated from the second source electrode, and
wherein in the second thin film transistor, the second drain electrode thereof defines the terminal of which the extended portion thereof defines the source electrode of the third film transistor.

Assignees

• Samsung Display Co Ltd

Inventors

• Han Min-Joo
• Yang Dan Bi
• Hong Ji Phyo
• Shin Ki Chul

Classifications

• H10D86/481

  integrated with passive devices, e.g. auxiliary capacitors · CPC title

• H10D86/441

  Interconnections, e.g. scanning lines · CPC title

• H10D86/60

  wherein the TFTs are in active matrices · CPC title

• H10D30/6891

  characterised by the shapes, relative sizes or dispositions of the floating gate electrode · CPC title

• H10D30/68

  Floating-gate IGFETs · CPC title