Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1999-09-14
2001-12-18
Shalwala, Bipin (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S087000, C349S106000, C349S110000, C349S111000, C359S016000
Reexamination Certificate
active
06331845
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display device and more particularly to the structure and the driving method of the display device which provides a high-quality display.
The conventional liquid crystal display device is constructed to have an active matrix substrate and a light-screening mask formed thereon so that the display device can provide a high-contrast panel as disclosed in JP-A-1-297623. This construction, however, has a shortcoming that the application of the construction to, in particular, a high-definition liquid crystal display device results in lowering a contrast ratio.
As disclosed in JP-A-2-10955, a storage capacitance element may be provided in parallel to a liquid crystal unit so as to suppress reduction of stored charges resulting from leakage current of a thin film transistor or a liquid crystal unit and diminish variation of an effective voltage. However, this storage capacitance element also has some difficulty in working the form of each element located on the substrate to be uniform on the plane of the substrate if the liquid crystal device is required to be more definitive and larger in size, resulting in disadvantageously making the dimensions of the elements provided on the substrate variable. The variation leaves an after image on the display device and degrades the liquid crystal.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a high-definition liquid crystal display device which is capable of diminishing leakage of light for realizing a high-contrast display and making a numerical aperture larger for providing a brighter display.
It is still another object of the present invention to provide a high-definition liquid crystal display device having structure of a storage capacitance element which is designed to diminish variation of a storage capacitance element located on a common potential electronic plane, the occurrence of short-circuit between wires, and a water mark for the purpose of improving a yield.
It is another object of the present invention to provide a driving method of the storage capacitance elements located on the liquid crystal display device which method is suitable to the reduction of variations of a common electric potential and a threshold value.
In order to achieve the foregoing objects, the present invention is constructed to provide an opaque material on one substrate having a thin film transistor formed thereon and an opaque material on another substrate having a color filter formed thereon so that those opaque materials serve to screen light applied from an area uncontrolled in response to an external voltage (signal voltage, scan voltage, etc.). The opaque materials keep a predetermined distance from the uncontrollable area. Further, in a TFT (thin film transistor) driving system liquid crystal device having two or more pixels located thereon including a first wire served as a scan signal line, a field-effect transistor (FET) whose gate electrode is connected to the first wire, a second wire served as a signal line and being connected to one of a drain and a source electrodes of the FET, a storage capacitance element one electrode of which is connected to the other of the drain and the source electrodes of the FET, a liquid crystal element one electrode of which is connected to the other of the drain and the source electrodes of the FET, a third electrode connected to the other electrode of the storage capacitance element, and a fourth electrode connected to the other electrode of the liquid crystal element and to the third electrode, the TFT driving system liquid crystal device is characterized in that a peripheral length &mgr;m of a capacitance section of the storage capacitance element is 1.33 times as large as or lower than a value obtained by dividing an area &mgr;m
2
of the capacitance section by a diagonal length of an area where the pixels are located and the third and the fourth electrodes are connected to a common electrode signal line. The capacitance section of the storage capacitance element has vertical and horizontal end portions which are terminated only on the end portions of either one of the electrodes of the storage capacitance element.
As described above, the peripheral length &mgr;m of the capacitance section of the storage capacitance element is 1.33 or less time as large as a value obtained by dividing an area &mgr;m
2
of the capacitance section by a diagonal length of an area where the pixels are located included in the display unit of the TFT driving system liquid crystal display device. It results in suppressing variation of areas of the storage capacitance elements, that is, variation of capacitance values resulting from the dimensional variation to a ±20% value of a central value.
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Funahata Katsuyuki
Kitajima Masaaki
Matsui Makoto
Mikami Yoshiro
Nagae Yoshiharu
Antonelli Terry Stout & Kraus LLP
Hitachi Ltd
Lewis David L.
Shalwala Bipin
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