Active matrix type display device

• US 6,531,993 B1
• Filed: 02/29/2000
• Issued: 03/11/2003
• Est. Priority Date: 03/05/1999
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Murakami, Satoshi, Koyama, Jun, Yamazaki, Shunpei, Tanaka, Yukio
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): ZAMANI, ALI A
• Application Number:
  US09/515,682
• Time in Patent Office: 1,106 Days
• Field of Search: 345/55, 345/92, 345/98, 345/100, 345/87, 345/90, 345/96, 345/206, 349/42, 349/43, 349/45, 257/59, 257/72, 257/347, 257/350, 257/351
• US Class Current: 345/55
• CPC Class Codes: G02F 1/13454 Drivers integrated on the active matrix substrate G02F1/136277 takes precedence
• CPC Class Codes: G02F 1/136209 Light shielding layers, e.g. black matrix, incorporated in the active matrix substrate, e.g. structurally associated with the switching element
• CPC Class Codes: G02F 1/136227 Through-hole connection of the pixel electrode to the active element through an insulation layer
• CPC Class Codes: G09G 2300/0876 Supplementary capacities in pixels having special driving circuits and electrodes instead of being connected to common electrode or ground; Use of additional capacitively coupled compensation electrodes
• CPC Class Codes: G09G 2310/0283 Arrangement of drivers for different directions of scanning
• CPC Class Codes: G09G 2310/0286 Details of a shift registers arranged for use in a driving circuit
• CPC Class Codes: G09G 2310/0289 Details of voltage level shifters arranged for use in a driving circuit
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3655 Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors
• CPC Class Codes: G09G 3/3688 suitable for active matrices only
• CPC Class Codes: H01L 27/1248 with a particular composition or shape of the interlayer dielectric specially adapted to the circuit arrangement
• CPC Class Codes: H01L 29/78633 with a light shield

Abstract

An active matrix type display device comprising:

a substrate;

a plurality of source signal lines and a plurality of gate signal lines formed over the substrate;

a plurality of pixel TFTs formed over the substrate;

a plurality of pixel electrodes electrically connected to said plurality of pixel TFTs;

a shielding film (black matrix) formed over said substrate wherein said shielding film is floating; and

a dielectric interposed between said pixel electrodes and said shielding film,

wherein signals whose polarity is inverted per each of said plurality of source signal lines are applied to said source signal lines and the polarity of said signal applied to the respective one of said plurality of source signal lines is inverted per one frame period. It is preferable to form acoupling capacitor between the shielding film and a common electrode.

Claims

1. An active matrix type display device comprising:

a substrate;

a plurality of pixel TFTs formed over the substrate;

a plurality of pixel electrodes electrically connected to said plurality of pixel TFTs;

a shielding film formed over said substrate wherein said shielding film is electrically floating; and

a dielectric interposed between said pixel electrodes and said shielding film; and

a plurality of holding capacitors wherein said holding capacitors comprise the plurality of pixel electrodes and the shielding film with the dielectric interposed therebetween.

5. The display device according to any one of claims 1 through 4, wherein said dielectric is an anode oxide film formed by anodizing said shielding film.

6. The display device according to any one of claims 1 through 4, wherein said shielding film comprises a metal selected from the group consisting of aluminum (Al), titanium (Ti) and tantalum (Ta).

7. The display device according to any one of claims 1 through 4, wherein a thickness of said shielding film is 100 to 300 nm.

9. A rear projector having three liquid crystal panels wherein each of the panels is the display device according to any one of claims 1 through 4.

10. A front projector having three liquid crystal panels wherein each of the panels is the display device according to any one of claims 1 through 4.

11. A rear projector having a single liquid crystal panel wherein the liquid crystal panel is the display device according to any one of claims 1 through 4.

12. A goggle type display device having two display panels wherein each of the display panels is the display device according to any one of claims 1 through 4.

13. The display device according to any one of claims 1 through 4 further comprising a coupling capacitor formed between the shielding film and an electrode wherein said electrode is formed simultaneously as the pixel electrodes.

2. An active matrix type display device comprising:

a substrate;

a plurality of source signal lines and a plurality of gate signal lines formed over the substrate;

a plurality of pixel TFTs formed over the substrate;

a plurality of pixel electrodes electrically connected to said plurality of pixel TFTs;

a shielding film formed over said substrate wherein said shielding film is electrically floating; and

a dielectric interposed between said pixel electrodes and said shielding film,

wherein signals whose polarity is inverted per each of said plurality of source signal lines are applied to said source signal lines and the polarity of said signal applied to the respective one of said plurality of source signal lines is inverted per one frame period.

3. An active matrix type liquid crystal display device comprising:

a first substrate;

a plurality of source signal lines and a plurality of gate signal lines formed over the first substrate;

a plurality of pixel TFTs formed over the first substrate, each of said pixel TFTs comprising an active layer including source and drain regions and a channel formation region, a gate electrode adjacent to said channel formation region with a gate insulating film interposed therebetween wherein the gate electrode is connected to corresponding one of the gate signal lines;

a plurality of pixel electrodes electrically connected to said plurality of pixel TFTs;

a shielding film formed over the first substrate wherein said shielding film is electrically floating;

a dielectric interposed between said pixel electrodes and said shielding film;

a second substrate opposed to said first substrate;

a liquid crystal interposed between said first and second substrates;

wherein signals whose polarity is inverted per each of said plurality of source signal lines are applied to said source signal lines and the polarity of said signal applied to the respective one of said plurality of source signal lines is inverted per one frame period.

8. The display device according to claim 3 or 4 wherein said gate electrode comprises a metal selected from the group consisting of titanium (Ti), tantalum (Ta), tungsten (W) and molybdenum (Mo).

4. An active matrix type liquid crystal display device comprising:

a first substrate;

a plurality of source signal lines and a plurality of gate signal lines formed over the first substrate;

a plurality of pixel TFTs formed over the first substrate, each of said pixel TFTs comprising an active layer including a pair of first impurity regions, a channel formation region between said first impurity regions, at least one second impurity region between the channel formation region and the first impurity regions, a gate electrode adjacent to said channel formation region with a gate insulating film interposed therebetween wherein the gate electrode is connected to corresponding one of the gate signal lines;

a plurality of pixel electrodes electrically connected to said plurality of pixel TFTs;

a shielding film formed over the first substrate wherein said shielding film is electrically floating;

a dielectric interposed between said pixel electrodes and said shielding film;

a second substrate opposed to said first substrate;

a liquid crystal interposed between said first and second substrates;

wherein said second impurity region is overlapped with said gate electrode with the gate insulating film therebetween, and signals whose polarity is inverted per each of said plurality of source signal lines are applied to said source signal lines, and the polarity of said signal applied to the respective one of said plurality of source signal lines is inverted per one frame period.

14. An active matrix type display device comprising:

a substrate;

a plurality of pixel electrodes formed over a display portion of the substrate;

a plurality of thin film transistors for switching said pixel electrodes;

a shielding film formed over the substrate wherein said shielding film is electrically floating;

a plurality of holding capacitors wherein said holding capacitors comprise the plurality of pixel electrodes and the shielding film with the dielectric interposed therebetween;

a common line connected to a fixed voltage over the substrate;

a first dielectric interposed between said shielding film and said pixel electrodes; and

a second dielectric interposed between said shielding film and said common line,

wherein said second dielectric does not overlap the display portion.

19. The display device according to any one of claims 14 through 18 wherein said first dielectric is an anode oxide film formed by anodizing said first shielding film.

20. The display device according to any one of claims 14 through 18 wherein said second dielectric is an anode oxide film formed by anodizing said second shielding film.

21. The display device according to any one of claims 14 through 18 wherein said shielding film comprises a metal selected from the group consisting of aluminum (Al), titanium (Ti) or tantalum (Ta).

22. The display device according to any one of claims 14 through 18 wherein said shielding film has a thickness of 100 to 300 nm.

23. The display device according to any one of claims 14 through 18 wherein said gate electrode comprises a metal selected from titanium (Ti), tantalum (Ta), tungsten (W) and molybdenum (Mo).

24. A rear projector having three liquid crystal panels wherein each of the panels is the display device according to any one of claims 14 through 18.

25. A front projector having three liquid crystal panels wherein each of the panels is the display device according to any one of claims 14 through 18.

26. A rear projector having a single liquid crystal panel wherein the liquid crystal panel is the display device according to any one of claims 14 through 18.

27. A goggle type display device having two display panels wherein each of the display panels is the display device according to any one of claims 14 through 18.

15. An active matrix type display device comprising:

a substrate;

a plurality of pixel electrodes formed over a display portion of the substrate;

a plurality of source signal lines and a plurality of gate signal lines formed over the substrate;

a plurality of pixel TFTs for switching said pixel electrodes;

a shielding film formed over said substrate wherein said shielding film is electrically floating;

a common line electrically connected to a fixed voltage formed over the substrate;

a first dielectric interposed between said pixel electrodes and said shielding film,

a second dielectric interposed between the shielding film and the common line;

wherein signals whose polarity is inverted per each of said plurality of source signal lines are applied to said source signal lines and the polarity of said signal applied to the respective one of said plurality of source signal lines is inverted per one frame period,

wherein said second dielectric does not overlap the display portion.

28. The display device according to any one of claims 2 through 4 and 15 through 18, further comprising holding capacitors wherein said holding capacitors comprise the plurality of the pixel electrodes and the shielding film with the dielectric interposed therebetween.

16. An active matrix type display device comprising:

a first substrate;

a plurality of pixel electrodes formed over a display portion of the first substrate;

a plurality of source signal lines and a plurality of gate signal lines formed over the first substrate;

a plurality of pixel TFTs for switching said pixel electrodes, each of said pixel TFTs comprising an active layer including source, drain and channel regions, and a gate electrode adjacent to the channel region with a gate insulating film interposed therebetween wherein said gate electrode is electrically connected to corresponding one of the gate signal lines;

a shielding film formed over said first substrate wherein said shielding film is electrically floating;

a common line electrically connected to a fixed voltage formed over the first substrate;

a first dielectric interposed between said pixel electrodes and said shielding film,

a second dielectric interposed between the shielding film and the common line;

a second substrate opposed to said first substrate; and

a liquid crystal interposed between the first and second substrates,

wherein signals whose polarity is inverted per each of said plurality of source signal lines are applied to said source signal lines and the polarity of said signal applied to the respective one of said plurality of source signal lines is inverted per one frame period, and

wherein said second dielectric does not overlap the display portion.

17. An active matrix type display device comprising:

a first substrate;

a plurality of pixel electrodes formed over a display portion of the first substrate;

a plurality of source signal lines and a plurality of gate signal lines formed over the firs substrate;

a plurality of pixel TFTs for switching said pixel electrodes, each of said pixel TFTs comprising an active layer including first impurity regions, a channel region interposed between the first impurity regions and at least one second impurity region between the channel region and the first impurity region, and a gate electrode adjacent to the channel region with a gate insulating film interposed therebetween wherein said gate electrode is electrically connected to corresponding one of the gate signal lines wherein said second impurity region is overlapped with the gate electrode with the gate insulating film interposed therebetween;

a shielding film formed over said first substrate wherein said shielding film is electrically floating;

a common line electrically connected to a fixed voltage formed over the first substrate;

a first dielectric interposed between said pixel electrodes and said shielding film,

a second dielectric interposed between the shielding film and the common line;

a second substrate opposed to said first substrate; and

a liquid crystal interposed between the first and second substrates,

wherein signals whose polarity is inverted per each of said plurality of source signal lines are applied to said source signal lines and the polarity of said signal applied to the respective one of said plurality of source signal lines is inverted per one frame period, and

wherein said second dielectric does not overlap the display portion.

18. An active matrix display device comprising:

a first substrate;

a plurality of pixel electrodes formed over a display portion of the substrate;

a plurality of thin film transistors for switching the pixel electrodes;

a shielding film formed over the first substrate wherein said shielding film is electrically floating;

a common line connected to a fixed voltage over the first substrate;

a source signal line driver circuit formed over the first substrate wherein said source signal line driver circuit includes a sampling circuit;

a first dielectric interposed between the pixel electrodes and the shielding film;

a second dielectric interposed between the shielding film and a conductive layer which is electrically connected to the common line; and

a second substrate provided with a counter shielding film,

wherein said second dielectric is not overlapped with the display portion, and said counter shielding film overlaps with said sampling circuit and a portion of said shielding film.