Display apparatus and manufacturing method thereof

• US 20030156240A1
• Filed: 12/27/2002
• Published: 08/21/2003
• Est. Priority Date: 12/28/2001
• Status: Active Grant

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Ishida, Satoshi, Yamada, Tsutomu, Oda, Nobuhiko
• Granted Patent: US 7,259,813 B2
• Time in Patent Office: Days
• US Class Current: 349/113
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/136227 Through-hole connection of the pixel electrode to the active element through an insulation layer
• CPC Class Codes: H10K 2102/3026 Top emission
• CPC Class Codes: H10K 50/856 comprising reflective means
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 59/878 comprising reflective means

Abstract

On a first substrate are formed a TFT provided to each pixel, an insulating film which covers the TFT, and a reflective layer which is provided on the insulating film so as to be insulated from the TFT and reflects light incident from a second substrate side. The reflective layer is covered with a passivation film on which a first electrode made of a transparent conductive material, such as ITO having the work function equivalent to a second electrode, is formed and connected to the TFT. The passivation film covering the reflective layer prevents the reflective surface of the reflective layer from deteriorating in reflection properties during a process for connecting the TFT and the first electrode. Further, the first and second electrodes having similar characteristics can symmetrically AC drive the liquid crystal layer.

Claims

1. A display apparatus configured by sandwiching a liquid crystal layer between a first substrate having a first electrode and a second substrate having a second electrode, wherein

said first substrate further comprises:

a switching element provided to each pixel and a reflective layer formed on an insulating film which covers said switching element so as to be insulated from said switching element, the reflective layer reflecting light incident from the second substrate and the second electrode, both of which are transparent, into said liquid crystal layer, and

a passivation film formed by covering said reflective layer, and wherein

said first electrode made of a transparent conductive material is electrically connected to said switching element via a contact hole penetrating said passivation film and said insulating film in a region corresponding to the switching element.

2. A display apparatus according to claim 1, wherein said switching element is a thin film transistor in which silicon is used for an active layer, and said first electrode directly contacts with said active layer of the thin film transistor.

3. A display apparatus according to claim 2, wherein the difference between a work function of said transparent conductive material used for said first electrode and a work function of said transparent conductive material used for said second electrode formed on a liquid crystal layer side of said second substrate is less than or equal to 0.5 eV.

4. A display apparatus according to claim 1, wherein the difference between a work function of said transparent conductive material used for said first electrode and a work function of said transparent conductive material used for said second electrode formed on a liquid crystal layer side of said second substrate is less than or equal to 0.5 eV.

5. A display apparatus according to claim 1, wherein the display apparatus is a liquid crystal display apparatus and the driving frequency for the liquid crystal layer for each pixel is less than 60 Hz.

6. A display apparatus according to claim 1, wherein

the display apparatus is a liquid crystal display apparatus,

said switching element is a thin film transistor in which silicon is used for an active layer,

said first electrode directly contacts with said active layer of the thin film transistor,

difference between a work function of the transparent conductive material used for said first electrode and a work function of the transparent conductive material used for said second electrode formed on the liquid crystal layer side of said second substrate is less than or equal to 0.5 eV, and

the driving frequency of the liquid crystal layer for each pixel is less than 60 Hz.

7. A method for manufacturing a display apparatus comprising a liquid crystal layer sandwiched between a first substrate having a first electrode and a second substrate having a second electrode, comprising steps of:

forming a thin film transistor on said first substrate,

covering said thin film transistor to form at least a single-layer insulating film,

covering said insulating film to form a reflective material layer which is then patterned such that the formed reflective material layer remains on a predetermined pixel region other than a region corresponding to the active layer of said thin film transistor to form a reflective layer,

covering said reflective layer to form a passivation film,

forming a contact hole which penetrates said passivation film and said insulating film on the region corresponding to the active layer of said thin film transistor so as to expose said active layer, and

covering said passivation film and said active layer exposed with transparent conductive material to form said first electrode which is then connected to said active layer through said contact hole.