Liquid crystal display comprising a storage capacitor including the closed-ended electrode for providing a current bath for circumventing break

• US 5,339,181 A
• Filed: 08/25/1992
• Issued: 08/16/1994
• Est. Priority Date: 09/05/1991
• Status: Expired due to Term

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Nam-deog, Son, Jeong-ha, Kim, Sang-soo, Jang, In-sik
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): MAI, HUY KIM
• Application Number:
  US07/934,396
• Time in Patent Office: 721 Days
• Field of Search: 359/54, 359/59, 359/67, 340/784, 340/719
• US Class Current: 349/38
• CPC Class Codes: G02F 1/136209 Light shielding layers, e.g. black matrix, incorporated in the active matrix substrate, e.g. structurally associated with the switching element
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode

Abstract

An active matrix LCD which essentially differs from presently available active matrix LCDs in that the layout of a first electrode of a storage capacitor associated with each pixel thereof is modified in such a manner as to significantly increase the aperture and contrast ratios thereof relative to those of presently available active matrix LCDs. More particularly, the first electrodes of the storage capacitors are laid out in such a manner as to substantially surround their associated pixel electrodes, and preferably, only overlap a marginal edge portion of their associated pixel electrodes, about the periphery thereof.

Claims

1. A liquid crystal display, including:

a front glass substrate having inboard and outboard surfaces;

a rear glass substrate having inboard and outboard surfaces, and oriented in parallel, spaced-apart relation to said front glass substrate, with said inboard surfaces of said front and rear glass substrates facing each other;

a plurality of rows of scanning signal electrodes and columns of display signal electrodes arranged in a matrix configuration on said inboard surface of said rear glass substrate, to thereby define a matrix of pixel regions, each of which is bounded by two adjacent ones of said rows of scanning signal electrodes and two adjacent ones of said columns of display signal electrodes;

a pixel electrode disposed in each of said pixel regions;

a switching element disposed in each of said pixel regions and connected between a respective one of said display signal electrodes and a respective one of said pixel electrodes;

a storage capacitor disposed in each of said pixel regions, wherein each said storage capacitor includes a first electrode overlapping a marginal edge portion of a respective one of said pixel electrodes around the entire periphery thereof, whereby said first electrode is closed-ended;

a black matrix light shield layer disposed on said inboard surface of said front glass substrate, said black matrix light shield layer being patterned in such a manner as to define a matrix of light transmissive apertures aligned with said matrix of pixel regions;

a color filter layer disposed on said inboard surface of said front glass substrate and overlying said black matrix light shield layer, said color filter layer including light transmissive portions overlying said light transmissive apertures;

a transparent electrode disposed over said color filter layer; and

,

a layer of liquid crystal sandwiched between said front glass substrate and said rear glass substrate.

2. The display as set forth in claim 1, further including a first protective layer interposed between said color filter layer and said transparent electrode.

3. The display as set forth in claim 1, wherein said first electrode of each said storage capacitor and said scanning signal electrodes lie in a common first plane, and said display signal electrodes and said pixel electrodes lie in a common second plane spaced from said first plane by an insulating layer disposed therebetween.

4. The display as set forth in claim 3, wherein each said switching element comprises a thin film transistor which includes:

a gate electrode which comprises an integral tab-like portion of a respective one of said scanning signal electrodes;

a source electrode which comprises an integral tab-like portion of a respective one of said display signal electrodes, said source electrode completely overlying said first electrode of a respective one of said storage capacitors;

a drain electrode which comprises said respective one of said display signal electrodes; and

,

a semiconductor layer disposed on said insulating layer and over said gate electrode, said semiconductor layer being patterned in such a manner as to interconnect said source electrode and said drain electrode.

5. The display as set forth in claim 4, wherein each said thin film transistor is disposed adjacent a corner of a respective one of said pixel regions, said corner being defined by the intersection of a respective one of said display signal electrodes with a respective one of said scanning signal electrodes.

6. The display as set forth in claim 1, wherein each said switching element is disposed adjacent a corner of a respective one of said pixel regions, said corner being defined by the intersection of a respective one of said display signal electrodes with a respective one of said scanning signal electrodes.

7. The display as set forth in claim 1, wherein the peripheral boundary of said apertures defined by edge portions of said black matrix light shield layer is aligned in substantial vertical registration with the inner, peripheral edge portion of said first electrode of respective ones of said storage capacitors, whereby said first electrodes of said respective ones of said storage capacitors function as additional light shield members for minimizing the amount of extraneous light allowed to be emitted through said apertures.

8. The display as set forth in claim 1, wherein the projection of each of said apertures through said rear glass substrate defines an imaginary aperture envelope, and, wherein further, said first electrode of respective ones of said storage capacitors do not extend into said imaginary aperture envelope.

9. The display as set forth in claim 1, wherein said first electrode of each said storage capacitor and each said scanning signal electrode are part of a common patterned layer.

10. The display as set forth in claim 9, wherein said common patterned layer is made of at least one opaque metal selected from the group comprised of aluminum, chromium, molybdenum and tantalum.

11. The display as set forth in claim 10, wherein each said switching element comprises a thin film transistor having a gate electrode which is also part of said common patterned layer.

12. A liquid crystal display, including:

a substrate;

a plurality of rows of scanning signal electrodes and columns of display signal electrodes arranged in a matrix configuration on a major surface of said substrate, to thereby define a matrix of pixel regions each of which is bounded by two adjacent ones of said rows of scanning signal electrodes and two adjacent ones of said columns of said display signal electrodes;

a pixel electrode disposed in each of said pixel regions;

a switching element disposed in each of said pixel regions and connected between a respective one of said display signal electrodes and a respective one of said pixel electrodes;

a storage capacitor disposed in each of said pixel regions, wherein each said storage capacitor includes a first electrode overlapping a marginal edge portion of a respective one of said pixel electrodes around the entire periphery thereby, whereby said first electrode is closed-ended.

13. The display as set forth in claim 12, wherein said first electrode of each said storage capacitor and said scanning signal electrodes lie in a common first plane, and said display signal electrodes and said pixel electrodes lie in a common second plane spaced from said first plane by an insulating layer disposed therebetween.