Active matrix type liquid crystal display apparatus

• US 5,831,707 A
• Filed: 08/24/1995
• Issued: 11/03/1998
• Est. Priority Date: 08/24/1994
• Status: Expired due to Term

• Current Assignee: Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Hitachi, Ltd.
• Inventors: Yanagawa, Kazuhiko, Kondo, Katsumi, Ando, Masahiko, Ohe, Masahito, Ota, Masuyuki
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Parker, Kenneth
• Application Number:
  US08/519,101
• Time in Patent Office: 1,167 Days
• Field of Search: 349/141, 349/139, 349/144, 349/39
• US Class Current: 349/141
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G09G 2300/0434 Flat panel display in which a field is applied parallel to the display plane
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

An active matrix type liquid crystal display apparatus includes a first substrate which has a plurality of scan electrodes and signal electrodes formed in a matrix shape, and a plurality of semiconductor switching elements having enhancement type characteristics formed at corresponding cross points of said scan electrodes and said signal electrodes, respectively, a second substrate which is arranged so as to face to said first substrate, and a liquid crystal layer which is composed of a liquid crystal composition enclosed in an interval between said first and second substrates, wherein pixel electrodes connected to corresponding said semiconductor switching element and counter electrodes connected to corresponding ones of said scan electrodes are arranged alternately in a comb-shape manner in respective ones of plural pixel regions surrounded by said plural scan electrodes and plural signal electrodes on said first substrate.

Claims

1. An active matrix type liquid crystal display apparatus comprising:

a pair of substrates, at least one of which is transparent; and

a liquid crystal layer composed of a liquid crystal composition enclosed in an interval between said pair of substrates;

wherein one substrate of said pair of substrates has formed thereon;

(a) a plurality of scan electrodes;

(b) a plurality of signal electrodes intercrossing with said plurality of scan electrodes in a matrix shape;

(c) a plurality of semiconductor switching elements formed at respective crossing points of said plurality of scan electrodes and said plurality of signal electrodes;

(d) at least one of a plurality of pixel electrodes connected to respective ones of said plurality of switching elements; and

(e) at least one of a plurality of counter electrodes connected to respective ones of said plurality of scan electrodes; and

wherein

respective ones of said plurality of pixel electrodes and said plurality of counter electrodes are arranged at a respective region surrounded by ones of said plurality of scan electrodes and ones of said plurality of signal electrodes; and

a voltage source is coupled to each corresponding pixel electrode by respective ones of said plurality of switching elements to supply an alternating voltage having a substantially symmetrical shape in positive and negative values taking a non-selective voltage level of said scan electrode as a standard.

2. An active matrix type liquid crystal display apparatus as claimed in claim 1, wherein

said semiconductor switching elements each comprise a thin film transistor element having enhancement type characteristics.

3. An active matrix type liquid crystal display apparatus as claimed in claim 2, wherein

an absolute value of a gate threshold value V_TH of said thin film transistor element is larger than an absolute value of the maximum value of voltage V_ON which is applied to the liquid crystal layer in order to effect transmittance of light in said liquid crystal layer maximum.

4. An active matrix type liquid crystal display apparatus as claimed in claim 2, wherein

an absolute value of a gate threshold value V_TH of said thin film transistor element is larger than a half of a difference between the maximum value of voltage V_ON and the minimum value of voltage V_OFF which is applied to the liquid crystal layer in order to effect transmittance of light in said liquid crystal layer maximum and minimum, respectively.

5. An active matrix type liquid crystal display apparatus as claimed in claim 2, wherein

said semiconductor switching elements have p-type or n-type characteristics, and

p-type thin film transistor elements and n-type thin film transistor elements are arranged in alternate lines of said scan electrodes.

6. An active matrix type liquid crystal display apparatus as claimed in claim 1, wherein

the substrate whereon said plurality of semiconductor switching elements are formed comprises:

a passivation film for protecting said semiconductor switching elements, and

back plane electrodes formed on said passivation film corresponding to respective ones of said semiconductor switching elements.

7. An active matrix type liquid crystal display apparatus as claimed in claim 6, wherein

said back plane electrode is arranged along said scan electrode.

8. An active matrix type liquid crystal display apparatus as claimed in either of claims 6 and 7, wherein

said back plane electrode is formed so as to shield a channel region of said semiconductor switching element.

9. An active matrix type liquid crystal display apparatus as claimed in either of claims 6 and 7, wherein

said back plane electrode is a floating electrode.

10. An active matrix type liquid crystal display apparatus as claimed in claim 1, wherein

said substrate whereon said plurality of semiconductor switching elements are formed comprises

back plane electrodes formed under said semiconductor switching element with an insulator disposed therebetween.

11. An active matrix type liquid crystal display apparatus as claimed in claim 10, wherein

said back plane electrode is arranged along said scan electrode.

12. An active matrix type liquid crystal display apparatus as claimed in claim 11, wherein

said back plane electrode is a floating electrode.

13. An active matrix type liquid crystal display apparatus as claimed in claim 1, wherein said substrate whereon said plurality of semiconductor switching elements are formed comprises a passivation film for protecting said semiconductor elements, said passivation film having impurities ion implanted therein.

14. An active matrix type liquid crystal display apparatus as claimed in claim 1, wherein said substrate whereon said plurality of semiconductor switching elements are formed comprises an insulator formed under said semiconductor switching elements, said insulator having impurities ion implanted therein.

15. An active matrix type liquid crystal display apparatus as claimed in claim 14, wherein

said plurality of semiconductor switching elements comprise:

metallic source electrodes connected to corresponding ones of said signal electrodes, and

metallic drain electrodes connected to corresponding ones of said pixel electrodes, and wherein

said plurality of semiconductor switching elements are in a staggered structure.

16. An active matrix type liquid crystal display apparatus comprising:

a first substrate which has a plurality of scan electrodes and signal electrodes formed in a matrix shape, and a plurality of semiconductor switching elements having enhancement type characteristics formed at corresponding cross points of said scan electrodes and said signal electrodes, respectively;

a second substrate which is arranged so as to face said first substrate; and

a liquid crystal layer which is composed of a liquid crystal composition enclosed in an interval between said first and second substrates;

wherein

pixel electrodes connected to corresponding ones of said semiconductor switching elements and counter electrodes connected to corresponding ones of said scan electrodes are arranged alternately in a comb-shape manner in respective ones of plural pixel regions surrounded with said plural scan electrodes and plural signal electrodes on said first substrate.

17. An active matrix type liquid crystal display apparatus as claimed in claim 16, wherein

said semiconductor switching elements each comprise a thin film transistor element.

18. An active matrix type liquid crystal display apparatus as claimed in claim 17, wherein

said thin film transistor element uses said scan electrode as a gate electrode, and comprises

a gate insulating layer formed on said gate electrode and

a semiconductor active layer formed on said gate insulating layer.

19. An active matrix type liquid crystal display apparatus as claimed in claim 18, wherein

said semiconductor active layer comprises

a semiconductor active layer doped with an acceptor or a donor.

20. An active matrix type liquid crystal display apparatus as claimed in claim 19, wherein

a pure semiconductor layer is laminated on said semiconductor active layer doped with said acceptor or said donor.

21. An active matrix type liquid crystal display apparatus as claimed in claim 18, wherein

said semiconductor active layer is composed of an amorphous silicon film.

22. An active matrix type liquid crystal display apparatus as claimed in claim 21, wherein

said gate insulating layer formed on the gate electrode of said thin film transistor element comprises either a SiON film or a SiO film.

23. An active matrix type liquid crystal display apparatus as claimed in claim 22, wherein

said gate insulating layer comprises either a SiN film laminated with a SiON film or a laminated SiO film.

24. An active matrix type liquid crystal display apparatus as claimed in claim 18, wherein

said thin film transistor elements comprise source electrodes and drain electrodes, both of which are formed on said semiconductor active layer,

said source electrodes and said drain electrodes are connected to corresponding ones of said signal electrodes and said pixel electrodes, respectively, and said gate electrodes are shifted toward said source electrode side or said drain electrode side.

25. An active matrix type liquid crystal display apparatus as claimed in claim 18, wherein

said gate electrode has an interval.

26. An active matrix type liquid crystal display apparatus as claimed in claim 16, wherein

an absolute value of a gate threshold value V_TH of said semiconductor switching element is larger than an absolute value of the maximum value of voltage V_ON which is applied to the liquid crystal layer in order to effect transmittance of light in said liquid crystal layer maximum.

27. An active matrix type liquid crystal display apparatus as claimed in claim 16, wherein

an absolute value of a gate threshold value V_TH of said semiconductor switching element is larger than a half of difference between the maximum value of voltage V_ON and the minimum value of voltage V_OFF which is applied to the liquid crystal layer in order to effect transmittance of light in said liquid crystal layer maximum and minimum, respectively.

28. An active matrix type liquid crystal display apparatus according to claim 16, wherein said pixel electrodes connected to corresponding ones of said semiconductor switching elements having enhancement type characteristics are connected so to have an alternating voltage applied thereto.

29. An active matrix type liquid crystal display apparatus comprising:

a first substrate which has a plurality of scan electrodes and signal electrodes formed in a matrix shape, and a plurality of semiconductor switching elements having enhancement type characteristics formed at corresponding cross points of said scan electrodes and said signal electrodes, respectively;

a second substrate which is arranged so as to face said first substrate; and

a liquid crystal layer which is composed of a liquid crystal composition enclosed in an interval between said first and second substrates;

wherein pixel electrodes connected to corresponding ones of said semiconductor switching elements and counter electrodes connected to corresponding ones of said scan electrodes are arranged alternately in a comb-shape manner in respective ones of plural pixel regions surrounded with said plural scan electrodes and plural signal electrodes on said first substrate;

wherein said semiconductor switching elements is a thin film transistor element; and

wherein an absolute value of a gate threshold value V_TH of said thin film transistor element is larger than an absolute value of the maximum value of voltage V_ON which is applied to the liquid crystal layer in order to effect transmittance of light in said liquid crystal layer maximum.

30. An active matrix type liquid crystal display apparatus comprising:

a first substrate which has a plurality of scan electrodes and signal electrodes formed in a matrix shape, and a plurality of semiconductor switching elements having enhancement type characteristics formed at corresponding cross points of said scan electrodes and said signal electrodes, respectively;

a second substrate which is arranged so as to face said first substrate; and

a liquid crystal layer which is composed of a liquid crystal composition enclosed in an interval between said first and second substrates;

wherein pixel electrodes connected to corresponding ones of said semiconductor switching elements and counter electrodes connected to corresponding ones of said scan electrodes are arranged alternately in a comb-shape manner in respective ones of plural pixel regions surrounded with said plural scan electrodes and plural signal electrodes on said first substrate;

wherein said semiconductor switching elements is a thin film transistor element; and

wherein an absolute value of a gate threshold value V_TH of said thin film transistor element is larger than a half of difference between the maximum value of voltage V_ON and the minimum value of voltage V_OFF which is applied to the liquid crystal layer in order to effect transmittance of light in said liquid crystal layer maximum and minimum, respectively.

31. An active matrix type liquid crystal display apparatus comprising:

a first substrate which has a plurality of scan electrodes and signal electrodes formed in a matrix shape, and a plurality of semiconductor switching elements having enhancement type characteristics formed at corresponding cross points of said scan electrodes and said signal electrodes, respectively;

a second substrate which is arranged so as to face said first substrate; and

a liquid crystal layer which is composed of a liquid crystal composition enclosed in an interval between said first and second substrates;

wherein pixel electrodes connected to corresponding ones of said semiconductor switching elements and counter electrodes connected to corresponding ones of said scan electrodes are arranged alternately in a comb-shape manner in respective ones of plural pixel regions surrounded with said plural scan electrodes and plural signal electrodes on said first substrate;

wherein said semiconductor switching elements is a thin film transistor element;

wherein said thin film transistor element uses said scan electrode as a gate electrode, and comprises a gate insulating layer formed on said gate electrode and a semiconductor active layer formed on said gate insulating layer;

wherein said semiconductor active layer comprises a semiconductor active layer doped with an acceptor or a donor; and

wherein a pure semiconductor layer is laminated on said semiconductor active layer doped with said acceptor or said donor.

32. An active matrix type liquid crystal display apparatus comprising:

a first substrate which has a plurality of scan electrodes and signal electrodes formed in a matrix shape, and a plurality of semiconductor switching elements having enhancement type characteristics formed at corresponding cross points of said scan electrodes and said signal electrodes, respectively;

a second substrate which is arranged so as to face said first substrate; and

a liquid crystal layer which is composed of a liquid crystal composition enclosed in an interval between said first and second substrates;

wherein

pixel electrodes connected to corresponding ones of said semiconductor switching elements and counter electrodes connected to corresponding ones of said scan electrodes are arranged alternately in a comb-shape manner in respective ones of plural pixel regions surrounded with said plural scan electrodes and plural signal electrodes on said first substrate;

wherein said semiconductor switching elements is a thin film transistor element;

wherein said thin film transistor element uses said scan electrode as a gate electrode, and comprises a gate insulating layer formed on said gate electrode and a semiconductor active layer formed on said gate insulating layer; and

wherein said thin film transistor elements comprise source electrodes and drain electrodes, both of which are formed on said semiconductor active layer, said source electrodes and said drain electrodes are connected to corresponding ones of said signal electrodes and said pixel electrodes, respectively, and said gate electrodes are shifted toward said source electrode side or said drain electrode side.

33. An active matrix type liquid crystal display apparatus comprising:

a first substrate which has a plurality of scan electrodes and signal electrodes formed in a matrix shape, and a plurality of semiconductor switching elements having enhancement type characteristics formed at corresponding cross points of said scan electrodes and said signal electrodes, respectively;

a second substrate which is arranged so as to face said first substrate; and

a liquid crystal layer which is composed of a liquid crystal composition enclosed in an interval between said first and second substrates;

wherein

pixel electrodes connected to corresponding ones of said semiconductor switching elements and counter electrodes connected to corresponding ones of said scan electrodes are arranged alternately in a comb-shape manner in respective ones of plural pixel regions surrounded with said plural scan electrodes and plural signal electrodes on said first substrate;

wherein said semiconductor switching elements is a thin film transistor element;

wherein said thin film transistor element uses said scan electrode as a gate electrode, and comprises a gate insulating layer formed on said gate electrode and a semiconductor active layer formed on said gate insulating layer; and

wherein said gate electrode has an interval.