Active matrix display with capacitive light shield

• US 4,759,610 A
• Filed: 09/29/1986
• Issued: 07/26/1988
• Est. Priority Date: 08/23/1983
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Yanagisawa, Toshio
• Primary Examiner(s): Miller, Stanley D.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/913,560
• Time in Patent Office: 666 Days
• Field of Search: 350/334, 350/339 F, 350/345, 357/30 L, 357/23.7
• US Class Current: 349/162
• CPC Class Codes: G02F 1/133512 Light shielding layers, e.g. black matrix G02F1/136209 takes precedence
• CPC Class Codes: G02F 1/133514 Colour filters
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G02F 2202/103 a-Si
• CPC Class Codes: G02F 2202/104 poly-Si
• CPC Class Codes: G02F 2202/106 Cd×Se or Cd×Te and alloys
• CPC Class Codes: H01L 29/78633 with a light shield

Abstract

In an active matrix type display apparatus which includes a first electrode substrate having a transparent insulation substrate on which a thin film transistor a transparent display pixel electrode selectively driven by the thin file transistor and a connecting portion for connecting the thin film transistor with the transparent display pixel electrode are formed, a second electrode substrate having another transparent insulation substrate on which an opposing electrode formed of a transparent conductive film is formed, and a display medium sandwiched between the first and second electrode substrates, an electrically conductive light shielding layer which is fixed at a predetermined potential is provided on each of thin film transistor portions of the first electrode substrate, and a part of the light shielding layer opposes a part of the transparent display pixel electrode through an insulation film so as to form a supplemental storage capacitor.

Claims

1. An active matrix type display apparatus, comprising:

a first transparent insulation substrate;

electrically conductive light shielding layer means maintained at a predetermined potential and formed on said first transparent substrate for shielding against light;

a first insulation film, deposited on said light shielding layer means;

a thin film transistor formed above and insulated from said light shielding layer means on said first insulation film, including;

(1) a semiconductor thin film, (2) a source electrode insulated from said light shielding layer means, (3) a drain electrode insulated from said light shielding layer means, (4) a gate insulating film disposed on said semiconductor thin film, and (5) a gate electrode insulated from said light shielding layer means and made of an opaque material disposed on said gate insulating film, said light shielding layer opposing said gate electrode with said semiconductor thin film therebetween;

a transparent display pixel electrode on said first transparent insulating substrate which is selectively addressed by said thin film transistor, a part of said light shielding layer means overlapping a part of said transparent display pixel electrode with said first insulation film therebetween to form an overlapping portion, wherein said light shielding layer means is also for forming a supplemental storage capacitor with said display pixel electrode at said overlapping portion;

a connecting portion on said thin first transparent insulation substrate for connecting said thin film transistor with said transparent display pixel electrode;

a drain bus formed on said insulating film and connected to said drain electrode;

a gate bus formed on said gate insulating film and connected to said gate electrode, said light shielding layer means not being connected to said drain bus and said gate bus;

a second transparent insulating substrate;

an opposing electrode formed on said second transparent insulating substrate formed of a transparent conductive film; and

a display liquid crystal medium, disposed between said first and second transparent insulation substrates and forming a signal voltage storage capacitor with said transparent display pixel electrode and said opposing electrode.

2. An apparatus according to claim 1, wherein said light shielding layer is formed of a metal selected from the group consisting of Al, Mo and Cr.

3. An apparatus according to claim 1, wherein said gate electrode is formed of aluminum.

4. An apparatus according to claim 1, wherein said display medium is a liquid crystal material.

5. An active matrix display apparatus, comprising:

a first transparent insulation substrate;

a thin film transistor formed on said first transparent insulation substrate and including a gate electrode made of an opaque material, a gate insulating film disposed on said gate electrode, a semiconductor thin film disposed on said gate insulating film, and source and drain electrodes;

a transparent display pixel electrode disposed on said first transparent insulation substrate coupled to said thin film transistor to be selectively addressed by said thin film transistor;

a gate thus formed on said first transparent insulation substrate and connected to said gate electrode;

a drain bus formed on said gate insulating film and connected to said drain electrode;

a connecting portion on said first transparent insulation substrate for connecting said thin film transistor with said transparent display electrode;

a second transparent insulation substrate;

an opposing electrode formed on said second transparent insulation substrate and formed of a transparent conductive film;

a liquid crystal medium disposed between said first and second transparent insulation substrates and forming a signal voltage storing capacitor with said transparent display pixel electrode and said opposing electrode;

an insulation film, formed on said thin film transistor; and

electrically conductive light shielding layer means for shielding against light penetration, maintained at a predetermined potential and formed over and insulating from said thin film transistor on said insulation film to oppose said gate electrode through said semiconductor thin film, with said light shielding layer means not being connected to and being insulated from said gate bus, said drain bus and said source electrode, and a part of said light shielding layer means opposing a part of said display pixel electrode with said insulation film therebetween, for forming a supplemental storage capacitor.

6. An apparatus according to claim 5, wherein said light shielding layer is formed of the metal selected from the group consisting of Al, Mo and Cr.

7. An apparatus according to claim 5, wherein said gate electrode is formed of aluminum.

8. An active matrix type display apparatus comprising:

a first transparent insulating substrate;

gate buses formed on said first transparent insulating substrate, said gate buses being sequentially scanned and driven by a scanning signal;

drain buses formed on said first transparent insulating substrate and having parallel image signal voltages applied thereto;

a thin film transistor array formed on said first transparent insulating substrate, said thin film transistor array having a plurality of thin film transistors including a semiconductor thin film, a source electrode, a drain electrode, a gate electrode and an insulating thin film between said gate electrode and said semiconductor thin film;

transparent display pixel electrodes formed on said first transparent insulating substrate, each of said pixel electrodes being selectively addressed by said thin film transistor array;

a second transparent insulating substrate;

a counter electrode formed on said second transparent electrode and made of transparent conductive film;

a liquid crystal medium disposed between said first and second transparent insulating substrates and forming a signal voltage storing capacitor with said transparent display pixel electrode and said counter electrode; and

an electrically conductive light shielding layer fixed at a predetermined potential, said conductive light shielding layer not being in contact with and being insulated from said thin film transistor and overlapping a part of said transparent display pixel electrode through an insulating film so as to form a supplemental storage capacitor layer, said light shielding layer not being connected to and being insulated from said gate buses, said drain buses and said source electrode, said light shielding layer and said gate electrode sandwiching said semiconductor thin film.