Liquid crystal cells – elements and systems – Particular excitation of liquid crystal – Electrical excitation of liquid crystal
Reexamination Certificate
1999-03-18
2003-09-09
Ton, Toan (Department: 2871)
Liquid crystal cells, elements and systems
Particular excitation of liquid crystal
Electrical excitation of liquid crystal
C349S044000, C349S051000
Reexamination Certificate
active
06618100
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a liquid crystal device that displays visible images, such as letters and numbers, by controlling the alignment of liquid crystal to modulate light. The present invention also relates to an electronic apparatus including the liquid crystal device. The present invention further relates to a manufacturing method of manufacturing such a liquid crystal device.
DESCRIPTION OF RELATED ART
(1) In recent years, a liquid crystal device has found use as a visible image display part in various types of electronic apparatuses, such as a car navigation system, and a portable electronic terminal. In a well-known type of liquid crystal device, a plurality of pairs of pixel electrodes and nonlinear elements are formed on an element substrate, opposite electrodes, and a color filter as needed, are formed on an opposite substrate, the element substrate and the opposite substrate are bonded to each other, and a cell gap formed between the substrates is sealed with liquid crystal.
Consideration will now be given to a liquid crystal device using a MIM (Metal Insulator Metal) element that is a typical example of a TFD (Thin Film Diode) element as a nonlinear element. A pattern structure including the surroundings of pixel electrodes and nonlinear elements formed on an element substrate in the liquid crystal device is conventionally formed as shown in, for example, FIG.
6
. Namely, a wire line
82
and a first electrode
83
are formed on a glass substrate
81
, an anodized film
84
is formed thereon, and a second electrode
86
is formed on the anodized film
84
. The layered structure including the first electrode
83
, the anodized film
84
, and the second electrode
86
forms a MIM element
87
serving as a nonlinear element. A pixel electrode
88
is formed so as to overlap with the leading end of the second electrode
86
in the MIM element
87
.
The pixel electrode
88
is generally formed by photolithography. Specifically, first, an ITO (Indium Tin Oxide) film having a uniform thickness is formed on the glass substrate
81
by sputtering or the like, and then, an unnecessary part of the ITO is removed by etching, thereby forming the pixel electrode
88
in a desired pattern. In this case, a problem is that gaps G are formed between the ITO film
88
′ and the second electrode
86
in forming the ITO film on the glass substrate
81
by sputtering or the like since the part of the ITO film
88
′ overlapping with the second electrode
86
of the MIM element does not completely adhere to the second electrode
86
.
If such gaps G are produced, when etching is performed later to pattern the ITO film
88
′, etchant may enter the gaps G, which may cause a wire break between the second electrode
86
and the pixel electrode
88
. Such a wire break can cause a dot defect in a visible image display area of the liquid crystal device. The transparent conductive film to be used as the pixel electrode may be made of SnOx, ZnOx, or the like instead of ITO. There is a fear that these film materials will insufficiently adhere to the second electrode
86
. Therefore, a wire break may be caused by etching these materials.
(2) In general, the liquid crystal devices include an active-matrix liquid crystal device in that nonlinear elements are provided for respective pixels, and a passive-matrix liquid crystal device that does not use such nonlinear elements. In the active-matrix liquid crystal device, an element substrate having nonlinear elements and transparent pixel electrodes and an opposite substrate having opposite electrodes are bonded to each other, and a cell gap formed between the substrates is sealed with liquid crystal.
Element substrates and opposite substrates are not fabricated one by one, and, in general, a plurality of element substrates and opposite substrates are formed in substrate base materials having a large area, respectively. By bonding the element substrate base material and the opposite substrate base material thus fabricated, a plurality of liquid crystal panels are simultaneously formed. The element substrate base material and the opposite substrate base material are bonded such as to align alignment marks that are formed at appropriate positions thereon.
In a conventional liquid crystal device manufacturing method, in order to confirm whether the element substrate base material and the opposite substrate base material are bonded in a proper positional relationship, an image of one pixel portion in the liquid crystal panel is formed by using an image pickup device such as a CCD camera and displayed on a screen of a CRT monitor or the like, or one pixel portion is microscopically observed, whereby it is examined whether the bonded state is proper from a positional point of view.
In a conventional inspection method, for example, the peripheral line of the transparent pixel electrode on the element substrate and a predetermined reference mark on the opposite substrate side, for example, the peripheral line of an opening portion of a black matrix, are compared with each other, and it is determined whether they are in a proper positional relationship. Thereby, it is determined whether the bonded state of the element substrate and the opposite substrate is good or bad. If it is good, the device is shipped as a product. If it is bad, the device is disposed of. Since the transparent pixel electrodes formed on the element substrate side are almost colorless and transparent, however, it is very difficult to perform a precise inspection in a short time in the case of the conventional liquid crystal device that is subjected to visual inspection with reference to the transparent pixel electrodes.
SUMMARY OF THE INVENTION
(3) The present invention has been made in view of the aforementioned problems, and an object of the present invention is to improve productivity of liquid crystal devices by providing an appropriate member on the periphery of a pixel electrode.
More specifically, a first object of the present invention is to provide an appropriate member on the periphery of a pixel electrode so as to prevent contact failure due to etching between a nonlinear element and the pixel electrode, and to prevent a dot defect in a visible image display area of a liquid crystal device.
A second object of the present invention is to provide an appropriate member on the periphery of a pixel electrode so as to precisely and visually detect the amount of offset between an element substrate and an opposite substrate in a short time.
(1) In order to achieve the above first object, the present invention provides a liquid crystal device having a plurality of pixel electrodes and a nonlinear element including an element-side electrode electrically connected to the pixel electrodes, wherein the element-side electrode is shaped in a pattern formed along the edge of the pixel electrode.
According to this liquid crystal device, since a part of the element-side electrode that overlaps with the pixel electrode is shaped like a pattern formed along the edge of the pixel electrode, when divided pixel electrodes are formed by etching an ITO film, etchant is prevented from entering between the element-side electrode and the ITO film. Therefore, it is possible to prevent a wire break between the element-side electrode and the ITO film.
(2) In the configuration mentioned above, it is preferable that the element-side electrode be shaped like a ring-shaped frame along the entire peripheral edge of the pixel electrode. This makes it possible to restrict the entry of etchant as much as possible, and to thereby more reliably prevent a wire break.
(3) Preferably, the outer dimensions of the element-side electrode are larger than that of the pixel electrode. This makes it possible to more reliably prevent the entry of the etchant.
(4) Next, in order to achieve the above first object, the present invention provides an electronic apparatus including a liquid crystal device having the aforementioned configuration, and a control unit for controlling the operati
Makino Naoki
Oike Kazuo
Yamaguchi Yoshio
Chung David
Oliff & Berridge PLC.
Seiko Epson Corporation
Ton Toan
LandOfFree
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