Active solid-state devices (e.g. – transistors – solid-state diode – Non-single crystal – or recrystallized – semiconductor... – Field effect device in non-single crystal – or...
Reexamination Certificate
2003-10-30
2004-12-28
Abraham, Fetsum (Department: 2826)
Active solid-state devices (e.g., transistors, solid-state diode
Non-single crystal, or recrystallized, semiconductor...
Field effect device in non-single crystal, or...
C257S059000
Reexamination Certificate
active
06835955
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to technical fields of electro-optical devices and electronic apparatuses, and in particular to, technical fields of an electro-optical device including storage capacitors for improving potential-maintaining characteristics of pixel electrodes, and an electronic apparatus including the electro-optical device. Also, the present invention relates to technical fields of electrophoresis devices, such as electronic paper, EL (electroluminescent) devices, devices using electron emission elements (Field Emission Display and Surface-Conduction Electron-Emitter Display), etc.
2. Description of Related Art
An electro-optical device is known which includes pixel electrodes arranged in a matrix, thin film transistors (hereinafter referred to as “TFTs”,) respectively connected to the electrodes, and scanning lines and data lines which are provided in parallel to row and column directions, whereby so-called active-matrix driving can be performed. This electro-optical device further includes a TFT array substrate on which the above pixel electrodes, the TFTs, etc., are formed, an opposing substrate on which a common electrode opposed to the array substrate is formed, and electro-optical material, such as liquid crystal provided between both substrates, whereby a picture can be displayed. Specifically, in active matrix driving, each predetermined picture signal is written in the predetermined pixel electrode, whereby an electric field corresponding to the picture signal is applied and changes the state of each pixel, thus changing the transmission factor of light. For example, see Patent Document 1.
In this case, for example, when the scanning lines are provided, a predetermined time is required, from a state in which TFTs connected to one scanning line are switched on to a state in which the TFTs are next switched on, until selection of all the scanning lines is completed. In addition, since a voltage applied to the pixel electrodes and the electro-optical material, such as liquid crystal, is attenuated in the predetermined time, the picture is affected, although the state is unchanged.
Accordingly, an electro-optical device of the related art may include a storage capacitor on the TFT array substrate, in addition to the above components. This is a capacitor which includes a pair of substrates having a dielectric film provided therebetween and in which, simultaneously with the application of picture signals to pixel electrodes and the application of a predetermined electric field to electro-optical material, such as liquid crystal, an equal electric field is applied to the capacitor. By utilizing this storage capacitor, during the selection period for all the scanning lines, as described above, typically, in, for example, one field, the electric field to the electrical material, such as liquid crystal can be maintained as it was originally applied. Thus, a high quality picture can be displayed.
Nevertheless, the electro-optical device of the related art has a problem in that the storage capacitance cannot be set sufficiently large. When the storage capacitance cannot be set sufficiently large, maintenance of the electric field applied to the electro-optical material, such as liquid crystal cannot sufficiently be performed during the all selection period, thus causing display non-uniformity, flickering, etc., in a picture.
Although there are demands to increase the storage capacitance in order to cope with the above problem, it is difficult to satisfy these demands as size reduction, increased resolution, or increased aperture ratio of the electro-optical device advances. By way of example, to simply realize an increase in storage capacitance, it is possible to attempt to increase the areas of upper and lower electrodes, etc., constituting the storage capacitor. However, in this case, it is impossible for the electro-optical device to cope with the fundamental demand to display a bright picture since a decrease in the aperture ratio is inevitable.
In addition, although, to achieve increased storage capacitance, it is possible to reduce the distance between the upper electrode and the lower electrode, that is, to make a dielectric film thin, such attempts have already reached their limit since, even in the present circumstances, large reductions in the thickness of the dielectric film have already been made.
SUMMARY OF THE INVENTION
The present invention is made to address the above problems, and provides an electro-optical device in which a high quality picture free from display non-uniformity, flickering, etc., can be displayed, with increased storage capacitance while maintaining a high aperture ratio, and an electronic apparatus including the electro-optical device.
To address the above problem, a first electro-optical device of an aspect of the present invention includes data lines extending in a first direction above a substrate, scanning lines which extend in a second direction and which cross the data lines, pixel electrodes and thin film transistors disposed so as to correspond to regions in which the data lines and the scanning lines cross, storage capacitors electrically connected to the thin film transistors and the pixel electrodes, and a shield layer disposed between the data lines and the pixel electrodes. An upper electrode and a lower electrode between which a dielectric film forming each storage capacitor is supported include a first portion laminated along a plane parallel with one surface of the substrate and a second portion laminated along a plane orthogonal to the surface of the substrate, whereby the sectional shape of the capacitor includes a projecting shape.
According to the first electro-optical device of an aspect of the present invention, firstly, scanning lines, data lines, pixel electrodes, and thin film transistors are provided, whereby active-matrix driving can be performed. Also, in the above electro-optical device, each of the above components of various types forms part of a laminated structure, whereby size reduction of the entire device can be achieved, and appropriate disposition of the components is realized, whereby a pixel aperture rate can be increased. Also, provision of a shield layer between each data line and each pixel electrode can reduce or prevent capacitive coupling from occurring between both. In other words, power supply to the data lines can reduce a possibility that a potential change in the pixel electrode, etc., occur, thus enabling display of a high quality picture. In addition, in an aspect of the present invention, a storage capacitor is provided which is formed by an upper electrode and a lower electrode between which a dielectric film is provided, and in which one of the upper electrode and the lower electrode is connected to the pixel electrode. Accordingly, when an electric field corresponding to the picture signal is applied to the pixel electrode, the same electric field is stored in the storage capacitor. Therefore, an electric field applied to liquid crystal can be maintained in a predetermined period. Thus, according to an aspect of the present invention, a high quality picture free from flickering, etc., can be displayed.
Here, in particular, in an aspect of the present invention, the storage capacitor includes a first portion laminated along a plane parallel to one surface of the substrate, with the dielectric film provided between the upper electrode and the lower electrode, and a second portion laminated along a plane orthogonal to the surface of the substrate, whereby the sectional shape of the capacitor includes a projecting shape. In other words, for example, in accordance with a case, such as the formation of the lower electrode so that it includes a projecting portion from the substrate, or the formation of a projecting member in a predetermined position below the lower electrode, the dielectric film and the upper electrode which are positioned above has a bending shape in a sectional view. In this case, compared with a plane storage c
Hayashi Tomohiko
Iki Takunori
Tsunekawa Yoshifumi
Abraham Fetsum
Oliff & Berridg,e PLC
Seiko Epson Corporation
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