Liquid crystal display panel having integrated pressure sensing units

• US 9,395,835 B2
• Filed: 06/15/2009
• Issued: 07/19/2016
• Est. Priority Date: 12/11/2008
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: No, Sang-Yong, Han, Sang-Youn, Cho, Young-Je
• Primary Examiner(s): FRY, MATTHEW A
• Application Number:
  US12/484,660
• Publication Number:
  US 20100149128A1
• Time in Patent Office: 2,591 Days
• Field of Search: 345173-174, 345/87, 178/18.06, 257/532, 257/535, 349 38- 39
• US Class Current: 1/1
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/13454 Drivers integrated on the active matrix substrate G02F1/136277 takes precedence
• 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

Capacitively actuated touch sensor units are integrated between subpixel light emitters of a liquid crystal display panel. In one embodiment, a sensor unit is monolithically integrated on a same substrate as are a plurality of associated subpixel units and the sensor unit includes a variable capacitor and a reference capacitor connected to define a voltage splitting circuit having a split voltage generating node. The sensor unit also includes a sensing transistor operatively coupled to the split voltage generating node and a voltage resetting transistor operatively coupled to the split voltage generating node. In one embodiment, one plate of the variable capacitor is defined by a touchwise flexed portion of a common electrode of the display and an opposed plate is defined by a spaced apart facing electrode provided on a TFT array substrate of the liquid crystal display.

Claims

1. A touch sensitive liquid crystal display panel comprising:

a plurality of subpixel units each comprising a liquid crystal capacitor having a pixel electrode and a common electrode of the display as two terminals with a liquid crystal layer interposed therebetween;

a touch sensing unit for generating a sensing data signal in response to an external contact;

a comparison signal generator for generating a comparison data signal regardless of the external contact; and

a contact determining unit for comparing the sensing data signal and the comparison data signal to determine existence of contact,

wherein the touch sensing unit comprises;

a voltage resetting transistor, a gate of the voltage resetting transistor being connected to a present gate line,

a variable capacitor having a capacitance that is changed by pressure, and having a first sensing electrode and the common electrode as two terminals,

a sensing element generating a detection signal based on a control voltage from the variable capacitor, and

a reference capacitor connected to the variable capacitor, and having the first sensing electrode and a previous gate line as two terminals, the previous gate line being a gate line activated ahead of the present gate line,

wherein the common electrode has a portion formed on a first protrusion,

wherein the first sensing electrode include a transparent conductive material and a conductive material connected to the transparent conductive material through a contact hole,

wherein the transparent conductive material does not overlap the first protrusion when the transparent conductive material and the first protrusion are projected onto a first substrate on which the transparent conductive material is disposed,

wherein the first sensing electrode is connected to a first transistor, a gate of the first transistor being connected to the present gate line,

wherein the comparison signal generator comprises;

a first comparison capacitor,

a comparison element generating a detection signal based on the control voltage from the first comparison capacitor,

a second comparison capacitor connected to the first comparison capacitor, and

a second sensing electrode forming one terminal of a first comparison capacitor and a second comparison capacitor, and

wherein the previous gate line forms the other terminal of the first comparison capacitor and the common electrode forms the other terminal of the second comparison capacitor.

2. The liquid crystal display of claim 1, further comprising a second protrusion protruded toward the second sensing electrode with respect to the common electrode,

wherein the first protrusion protruded toward the first sensing electrode with respect to the common electrode;

and

wherein the height of the second protrusion is the same as or lower than the height of the first protrusion.