Active matrix liquid crystal display and method of fabricating same

• US 6,246,454 B1
• Filed: 12/20/1996
• Issued: 06/12/2001
• Est. Priority Date: 12/19/1995
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.), Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.), Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Koyama, Jun, Yamamoto, Yoshitaka
• Primary Examiner(s): Dudek, James A.
• Assistant Examiner(s): Duong, Tai V.
• Application Number:
  US08/770,785
• Time in Patent Office: 1,635 Days
• Field of Search: 349/40, 349/149, 349/151, 349/153, 349/158, 349/159, 349/187, 349/190, 257/57, 257/72, 257/356, 257/363, 345/206
• US Class Current: 349/40
• CPC Class Codes: G02F 1/13454 Drivers integrated on the active matrix substrate G02F1/136277 takes precedence
• CPC Class Codes: G02F 1/136204 Arrangements to prevent high voltage or static electricity failures

Abstract

There is disclosed a small-sized, active matrix liquid crystal display having high reliability. The liquid crystal display comprises a TFT substrate, a counter substrate, and a layer of a liquid crystal material held between these two substrates. A plurality of pixel TFTs are arranged in rows and columns on the TFT substrate. Driver TFTs forming a driver circuit for driving the pixel TFTs are formed also on the TFT substrate. All of these TFTs are covered by the liquid crystal material directly or via a thin film to protect these TFTs. A short ring is cut after a rubbing operation and before bonding of the substrates. Therefore, during manufacturing, the TFTs are protected from static charges. Also, the cutting operation is facilitated.

Claims

1. An active matrix liquid crystal display comprising:

a pixel thin film transistor provided over a TFT substrate;

driver thin film transistors formed over said TFT substrate and forming a driver circuit for driving said pixel thin film transistor;

a bus line provided over said TFT substrate and connected with said pixel thin film transistor, an end of said bus line being apart from an adjacent end surface of said TFT substrate thereto toward an inside of said TFT substrate;

a counter substrate located opposite to said TFT substrate; and

a layer of a liquid crystal material with which said pixel thin film transistor and driver thin film transistors are in contact directly or via a thin film, said layer of the liquid crystal material being provided between said TFT substrate and said counter substrate; and

a pattern comprising same material as said bus line and formed at said end surface of said TFT substrate over said TFT substrate in same layer as said bus line,

wherein said end of said bus line is apart from said pattern toward an inside of said TFT substrate.

2. The display of claim 1, further comprising a control circuit for controlling said driver circuit made up of said driver thin film transistors, said control circuit being packed over said TFT substrate, and wherein said control circuit is sealed in a sealant material of said liquid crystal material placed over said TFT substrate.

3. The display of claim 1, further comprising a control circuit disposed at a control circuit accommodation portion of the TFT substrate, the control circuit accommodation portion being thinner than other portions of the TFT substrate.

4. The display of claim 1, further comprising a control circuit disposed at a control circuit accommodation portion of the counter substrate, the control circuit accommodation portion being thinner than other portions of the counter substrate.

5. The display of claim 2, wherein said control circuit is packed on said TFT substrate by COG (chip-on-glass) technology.

6. The display of claim 3, wherein said control circuit is packed on said TFT substrate by COG (chip-on-glass) technology.

7. The display of claim 4, wherein said control circuit is packed on said TFT substrate by COG (chip-on-glass) technology.

31. The display of claim 1, further comprising other bus lines and other pixel thin film transistors provided over said TFT substrate wherein said other bus lines are connected with said other pixel thin film transistors, respectively, and said bus line and said other bus lines are connected with each other by said short ring.

34. The display of claim 1 wherein said pattern has a shape of at least a part of a short ring.

36. The display of claim 1 further comprising a control circuit provided over said TFT substrate on a side of said TFT substrate distant from saved pattern.

8. An active matrix liquid crystal display comprising:

a pixel thin film transistor provided over a TFT substrate and in an active matrix circuit;

driver thin film transistors formed over said TFT substrate and forming a driver circuit for driving said pixel thin film transistor;

a bus line provided over said TFT substrate and connected with said pixel thin film transistor, an end of said bus line being apart from an adjacent end surface of said TFT substrate thereto toward an inside of said TFT substrate;

a counter substrate located opposite to said TFT substrate;

a sealant material provided between said TFT substrate and said counter substrate;

a layer of a liquid crystal material with which said pixel thin film transistor and driver thin film transistors are in contact directly or via a thin film, said layer of the liquid crystal material being provided between said TFT substrate and said counter substrate, said liquid crystal material being sealed by said sealant material between said TFT substrate and said counter substrate; and

a pattern comprising same material as said bus line and formed at said end surface of said TFT substrate over said TFT substrate in same layer as said bus line,

wherein said end of said bus line is apart from said pattern toward an inside of said TFT substrate.

9. The display of claim 8, further comprising a control circuit for controlling said driver circuit made up of said driver thin film transistors, said control circuit being packed over said TFT substrate, and wherein said control circuit is sealed in said sealant material placed over said TFT substrate.

10. The display of claim 8, further comprising a control circuit disposed at a control circuit accommodation portion of the TFT substrate, the control circuit accommodation portion being thinner than other portions of the TFT substrate.

11. The display of claim 8, further comprising a control circuit disposed at a control circuit accommodation portion of the counter substrate, the control circuit accommodation portion being thinner than other portions of the counter substrate.

12. The display of claim 9, wherein said control circuit is packed on said TFT substrate by COG (chip-on-glass) technology.

13. The display of claim 10, wherein said control circuit is packed on said TFT substrate by COG (chip-on-glass) technology.

14. The display of claim 11, wherein said control circuit is packed on said TFT substrate by COG (chip-on-glass) technology.

32. The display of claim 8, further comprising other bus lines and other pixel thin film transistors provided over said TFT substrate wherein said other bus lines are connected with said other pixel thin film transistors, respectively, and said bus line and said other bus lines are connected with each other by said short ring.

35. The display of claim 8 wherein said pattern has a shape of at least a part of a short ring.

37. The display of claim 8 further comprising a control circuit provided over said TFT substrate on a side of said TFT substrate distant from said pattern.

15. A method of fabricating an active matrix liquid crystal display having a pixel thin film transistor over a TFT substrate, driver thin film transistors formed over said TFT substrate and forming a driver circuit for driving said pixel thin film transistor, a bus line provided over said TFT substrate and connected with said pixel thin film transistor, a counter substrate located opposite to said TFT substrate, and a layer of a liquid crystal material with which said pixel thin film transistor and driver thin film transistors are in contact directly or via a thin film, said layer of the liquid crystal material being provided between said TFT substrate and said counter substrate, said method comprising the steps of:

performing a rubbing operation;

then separating a short ring provided at an end surface of said TFT substrate from said bus line by cutting said bus line from said short ring while said end surface of said TFT substrate and said short ring are left uncut;

printing a sealant material over at least one of said TFT substrate and said counter substrate after the separating step; and

then bonding together said TFT substrate and said counter substrate after the printing step while said TFT substrate has said end surface of said TFT substrate and the separated short ring.

16. The method of claim 15, further comprising the steps of:

packing a control circuit for controlling said driver circuit made up of said driver thin film transistors, over said TFT substrate; and

sealing said control circuit for controlling said driver circuit made up of said driver thin film transistors in a sealant material that seals said liquid crystal material, said sealant material being positioned over said TFT substrate.

17. The method of claim 15, further comprising the step of thinning a control circuit accommodation portion of said TFT substrate to install a control circuit for controlling said driver circuit made up of said driver thin film transistors in said control circuit accommodation portion of said TFT substrate.

18. The method of claim 15, further comprising the step of thinning a portion of said counter substrate located opposite to a control circuit accommodation portion of said TFT substrate, in order to install a control circuit for controlling said driver circuit in said control circuit accommodation portion of said TFT substrate.

19. The method of claim 16, wherein said control circuit is packed on said TFT substrate by COG (chip-on-glass) technology.

20. The method of claim 17, wherein said control circuit is packed on said TFT substrate by COG (chip-on-glass) technology.

21. The method of claim 18, wherein said control circuit is packed on said TFT substrate by COG (chip-on-glass) technology.

33. The method of claim 15, wherein said active matrix liquid crystal display further comprises other bus lines and other pixel thin film transistors provided over said TFT substrate wherein said other bus lines are connected with said other pixel thin film transistors, respectively, and said bus line and said other bus lines are connected with each other by said short ring.

22. A method of fabricating an active matrix liquid crystal display having a pixel thin film transistor over a TFT substrate, driver thin film transistors formed over said TFT substrate and forming a driver circuit for driving said pixel thin film transistor, a bus line connected with said pixel thin film transistor and provided over said TFT substrate, a short ring provided at an end surface of said TFT substrate, a counter substrate located opposite to said TFT substrate, and a layer of a liquid crystal material with which said pixel thin film transistor and driver thin film transistors are in contact directly or via a thin film, said layer of the liquid crystal material being provided between said TFT substrate and said counter substrate, said method comprising the steps of:

performing a rubbing operation on an orientation film provided over at least said TFT substrate while said short ring and said bus line are connected with each other by a continuous form from said short ring to said bus line;

separating said short ring from said bus line connected with said pixel thin film transistor by laser cutting said bus line from said short ring after said rubbing operation while said end surface of said TFT substrate and said short ring are left uncut;

printing a sealant material over at least one of said TFT substrate and said counter substrate after the separating step; and

then bonding together said TFT substrate and said counter substrate while said TFT substrate has said end surface of said TFT substrate and the separated short ring.

23. The method of claim 22, further comprising the steps of:

packing a control circuit for controlling said driver circuit made up of said driver thin film transistors, over said TFT substrate; and

sealing said control circuit for controlling said driver circuit made up of said driver thin film transistors in a sealant material that seals said liquid crystal material, said sealant material being positioned over said TFT substrate.

24. The method of claim 22, further comprising the step of thinning a control circuit accommodation portion of said TFT substrate in order to install a control circuit for controlling said driver circuit made up of said driver TFTs in said control circuit accommodation portion.

25. The method of claim 22, further comprising the step of thinning a portion of said counter substrate located opposite to a control circuit accommodation portion of said TFT substrate, in order to install a control circuit for controlling said driver circuit in said control circuit accommodation portion.

26. The method of claim 23, wherein said control circuit is packed on said TFT substrate by COG (chip-on-glass) technology.

27. The method of claim 24, wherein said control circuit is packed on said TFT substrate by COG (chip-on-glass) technology.

28. The method of claim 25, wherein said control circuit is packed on said TFT substrate by COG (chip-on-glass) technology.

29. A method of fabricating an active matrix liquid crystal display having a pixel thin film transistor over a TFT substrate, driver thin film transistors formed over said TFT substrate and forming a driver circuit for driving said pixel thin film transistor, a bus line connected with said pixel thin film transistor and provided over said TFT substrate, a short ring provided at an end surface of said TFT substrate, a control circuit provided over said TFT substrate for controlling said driver circuit, a counter substrate located opposite to said TFT substrate, and a layer of a liquid crystal material with which said pixel thin film transistor and driver thin film transistors are in contact directly or via a thin film, said layer of the liquid crystal material being provided between said TFT substrate and said counter substrate, said method comprising the steps of:

performing a rubbing operation on an orientation film provided over at least said TFT substrate while said short ring and said bus line are connected with each other by a continuous form from said short ring to said bus line;

separating said short ring from said bus line connected with said pixel thin film transistor by cutting said bus line from said short ring at a side of said TFT substrate distant from said control circuit after said rubbing operation while said end surface of said TFT substrate and said short ring are left uncut;

printing a sealant material over at least one of said TFT substrate and said counter substrate after the separating step; and

then bonding together said TFT substrate and said counter substrate while said TFT substrate has said end surface of said TFT substrate and the separated short ring.

30. The method of claim 29, wherein said cutting is laser cutting.