Display apparatus and method for manufacturing the same

• US 20030156239A1
• Filed: 12/27/2002
• Published: 08/21/2003
• Est. Priority Date: 12/28/2001
• Status: Abandoned Application

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Koma, Norio, Ogawa, Shinji, Inoue, Kazuhiro, Ishida, Satoshi, Yamada, Tsutomu, Yamashita, Tohru, Oda, Nobuhiko
• Application Number:
  US10/330,905
• Publication Number:
  US 20030156239A1
• 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 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: G02F 1/136227 Through-hole connection of the pixel electrode to the active element through an insulation layer
• CPC Class Codes: G02F 2201/121 common or background
• CPC Class Codes: G02F 2203/01 transmissive
• CPC Class Codes: H10K 2102/3026 Top emission
• CPC Class Codes: H10K 50/828 Transparent cathodes, e.g. comprising thin metal layers
• CPC Class Codes: H10K 50/856 comprising reflective means
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 59/123 Connection of the pixel electrodes to the thin film transistors [TFT]
• CPC Class Codes: H10K 59/126 Shielding, e.g. light-blocking means over the TFTs
• CPC Class Codes: H10K 59/80524 Transparent cathodes, e.g. comprising thin metal layers
• CPC Class Codes: H10K 59/878 comprising reflective means

Abstract

On a first substrate, a TFT which is a switching element is provided for each pixel, and above an insulating film covering this TFT, a reflective layer which is insulated from the TFT and which reflects light entering a second substrate and transmitting through a second electrode made of ITO is formed. Further, a first electrode having a work function similar to that of the second electrode and made of a transparent conductive material such as ITO is formed closer to a liquid crystal layer than the reflective layer, and this first electrode is connected with the TFT. With this configuration, the liquid crystal layer can be symmetrically AC driven by the first and second electrodes. A reliable connection between the first electrode and the TFT is provided through a connection metal layer made of a refractory metal.

Claims

1. A display apparatus comprising a first substrate having a first electrode, a second substrate having a second electrode, and a liquid crystal layer sealed between the first substrate and the second substrate for performing display, wherein

the first substrate further includes:

a switching element provided for each pixel; and

a reflective layer which is formed on an insulating film covering the switching element so as to be insulated from the switching element, the reflective layer reflecting light entering the liquid crystal layer through the second substrate; and

wherein

the first electrode is formed by a transparent conductive material so as to directly cover the reflective layer and is electrically connected with the switching element.

2. A display apparatus according to claim 1, wherein

a connection metal layer is formed within a contact hole formed in the insulating film covering the switching element, and

the switching element and the first electrode are electrically connected via the connection metal layer.

3. A display apparatus according to claim 2, wherein

the connection metal layer includes a refractory metal material at least on a surface contacting the first electrode.

4. A display apparatus according to claim 2, wherein

a difference between a work function of the transparent conductive material of the first electrode and a work function of a transparent conductive material formed on a side of the second substrate toward the liquid crystal layer is 0.5 eV or less.

5. A display apparatus according to claim 1, wherein

a difference between a work function of the transparent conductive material of the first electrode and a work function of a transparent conductive material of the second electrode which is formed on the second substrate toward the liquid crystal layer is 0.5 eV or less.

6. A display apparatus according to claim 5, wherein

a drive frequency for the liquid crystal layer in each pixel is less than 60 Hz.

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

forming a thin film transistor on the first substrate side;

forming an insulating film formed from at least one layer so as to cover the thin film transistor;

forming a contact hole in a region of the insulating film corresponding to an active layer of the thin film transistor;

forming a connection metal layer in the region of the contact hole;

forming a reflective material layer so as to cover the insulating film and the connection metal layer and patterning the reflective material layer so that the reflective material layer remains in a predetermined pixel region other than a region above the connection metal layer, to form a reflective layer; and

forming the first electrode from a transparent conductive material so as to cover the reflective layer and the connection metal layer and electrically connecting the first electrode to the thin film transistor via the connection metal layer.