Matrix liquid crystal, display device having testing pads of transparent conductive film

• US 5,530,568 A
• Filed: 11/25/1994
• Issued: 06/25/1996
• Est. Priority Date: 11/25/1993
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Yamamoto, Hideaki, Matsumaru, Haruo, Tsukii, Michio, Shirahashi, Kazuo
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Duong, Tai V.
• Application Number:
  US08/348,104
• Time in Patent Office: 578 Days
• Field of Search: 359/54, 359/59, 359/60, 359/87, 359/88, 445/3, 445/24, 257/784, 345/87, 345/90, 345/92
• US Class Current: 349/143
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: G02F 1/1345 Conductors connecting electrodes to cell terminals
• CPC Class Codes: G02F 1/1362 Active matrix addressed cells G02F1/134336, G02F1/134363 take precedence
• CPC Class Codes: G02F 1/136254 Checking; Testing

Abstract

A liquid crystal display device comprises: a liquid crystal display panel including a liquid crystal interposed between first and second transparent plates; a set of conductive lines disposed on a surface of at least one of said transparent plates; and a set of electrically conductive pads connected to respective first ends of the conductive lines. Each of the conductive lines has a lower layer made of aluminum or aluminum alloy and an upper layer made of a transparent conductive film. The aluminum or aluminum alloy layers in the conductive lines do not extend into any of the layers used to construct the pads. Each pad, instead, is formed of only a transparent conductive film. Additionally, the conductive lines have respective second ends which are commonly connected to a short-circuiting line. Disposed within the line is another electrically conductive pad, constructed in the fashion the pads in the aforementioned set are constructed. The pad in the short-circuiting line advantageously functions to receive test signals from a probe individually input into the pads at the first ends of the conductive lines. A user therefore can identify faulty conductive lines by determining whether test signals input into the pads at the first end of the lines are received at the pad in the short-circuiting line.

Claims

1. A liquid crystal display device comprising:

a liquid crystal display panel including a liquid crystal interposed between first and second transparent plates;

a set of conductive lines disposed on a surface of at least one of said transparent plates, each of said lines having a lower layer made of aluminum or aluminum alloy and an upper layer made of a transparent conductive film; and

a set of electrically conductive pads are disposed at respective first ends of said conductive lines, said pads being made of only a transparent conductive film containing neither said aluminum nor aluminum alloy.

3. The liquid crystal display device according to claim 1 or 2,

wherein said aluminum alloy contains tantalum, titanium or both.

4. The liquid crystal display device according to claim 1, 2, or 3,

wherein said transparent conductive film, thinner than said aluminum or aluminum alloy film, is formed to override sloped end portion of said aluminum or aluminum alloy film.

5. A liquid crystal display device as recited in claim 1, further comprising:

a short-circuiting line connected to respective second ends of said electrically conductive pads; and

an electrically conductive pad, different from any one of said set of pads, connected to the short-circuiting line.

6. A liquid crystal display device as recited in claim 5, wherein each pad in said set of pads is adapted to receive test signals from a probe, said different pad functioning to receive said test signals along individual conductive paths formed between said short-circuiting line and each respective conductive line, and

further wherein a user may identify faulty conductive lines by determining whether a test signal input into any one of said pads is detected at said different pad.

7. A liquid crystal display device as recited in claim 6, wherein said conductive lines are cut in advance of said second ends to separate each of said conductive lines from said short-circuiting line.

2. A liquid crystal display device comprising:

a liquid crystal display panel including a liquid crystal interposed between first and second transparent plates;

a set of conductive lines disposed on a surface of at least one of said transparent plates, each of said lines having a lower layer made of an aluminum or aluminum alloy and an upper layer made of a transparent conductive film;

wherein said conductive lines have respective first and second ends, said second ends being commonly connected to a short-circuiting line and said first ends being connected respectively to a set of electrically conductive pads, and

wherein said electrically conductive pads are made of only a transparent conductive film containing neither said aluminum or aluminum alloy, and further wherein said conductive lines are each cut in advance of said second ends to separate each of said conductive lines.

8. A liquid crystal display device as recited in claim 2, wherein said electrically conductive pads are testing pads.