Liquid crystal cells – elements and systems – Nominal manufacturing methods or post manufacturing...
Utility Patent
1998-12-11
2001-01-02
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
Nominal manufacturing methods or post manufacturing...
C349S113000
Utility Patent
active
06169593
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a reflection-type liquid crystal display device in wide use as a display device in, for example, personal computers, mobile computer terminals, AV equipment, and car navigation devices, and a method for producing the same, and further to a method for producing a circuit board. In this specification, a liquid crystal display device is referred to as an “LCD device”.
2. Description of the Related Art
Conventionally, an LCD device of a transmission-type including a backlight for supplying from a rear part thereof is the mainstream device. Recently, a reflection-type LCD device utilizing ambient light has been actively developed in order to fulfil the demands of lower power consumption, reduced weight and reduced thickness.
A reflection-type LCD device including a reflective plate outside the glass substrate results in blurred images. In order to solve this problem, most reflection-type LCD devices include a reflective plate inside the glass substrate so as to be in contact with the liquid crystal layer.
A reflection-type device has a terminal section for connection of ICs or a circuit board for driving the LCD panel and a terminal section for examining the LCD panel.
A structure of a conventional terminal section is disclosed by, for example, Japanese Laid-Open Publication No. 7-325295.
FIG. 14A
shows another conventional terminal section having a multiple-layer structure with steps, which is common today since more and more LCD devices are produced by a dry process, especially for film formation, in order to improve the precision. In order to produce conventional LCD devices which do not require high precision, a gate insulating layer is allowed to be formed at a prescribed position by a wet process. Therefore, an interlayer insulating layer does not exist in the terminal section. In contrast, in the case of a dry process, an interlayer insulating layer is formed substantially entirely on a base plate and thus the terminal section has a multiple-layer structure with the steps.
With reference to
FIG. 14A
, a conventional terminal section for connecting a gate signal line and a gate driving IC to each other will be described. The terminal section includes an insulating plate
120
, a gate signal line
122
provided on the insulating plate
120
, and the gate insulating layer
124
provided substantially entirely on the glass plate
120
. The insulating layer
124
is formed by a dry process. The gate insulating layer
124
acts as an interlayer insulating layer between the gate signal line
122
and the source signal line (not shown). The terminal section further includes a conductive layer
126
provided on the gate signal line
122
so as to overlap an end of the gate insulating layer
124
. The conductive layer
126
is formed of an identical material as that of the source signal line and is disconnected from the source signal line. An ITO layer
128
is provided on the conductive layer
126
. As shown here, the conventional terminal section has a multiple-layer structure with steps and the ITO layer
128
is provided at the top.
When such a conventional terminal section is applied to a reflection-type LCD device, the following problem occurs. A reflective layer (not shown) which is formed of Al and is equivalent to the reflective plate (acting also as a pixel electrode) is provided in the terminal section in addition to a display area (not shown). When the reflective layer is patterned to a prescribed shape, the ITO layer
128
in the terminal section is at least partially removed together with the reflective layer, causing many inconveniences.
In order to solve these inconveniences, as shown in
FIG. 14B
, an insulating resin layer
130
is provided on the ITO layer
128
so as to avoid direct contact between the ITO layer
128
and the reflective layer
132
(
FIG. 14C
) which is to be provided on the insulating resin layer
130
as shown in FIG.
14
C. Even by such a structure, since the ITO layer
128
has an uneven surface, a part of the ITO layer
128
is not covered by the insulating resin layer
130
and is in direct contact with the reflective layer
132
.
When the reflective layer
132
is removed, electrolytic corrosion at least partially removes the ITO layer
128
, which significantly reduces the production yield.
SUMMARY OF THE INVENTION
According to one aspect of the invention, a method for producing a reflection-type liquid crystal display device, including a first substrate; a second substrate; and a display medium layer interposed between the first substrate and the second substrate is provided. The first substrate includes a first electrode for applying a voltage to the display medium layer. The second substrate includes a second electrode for applying a voltage to the display medium layer. The first substrate includes a light reflective section in the vicinity of the display medium layer for reflecting light which is incident on the reflection-type liquid crystal display device through the second substrate, and includes a plurality of terminal sections for supplying a voltage to the first electrode and the second electrode. At least one of the plurality of terminal sections has a top layer formed of ITO, only a flat area of a top surface of the top layer being exposed. The method includes the steps of forming an ITO layer in the first substrate; patterning the ITO layer to form the top layer in the at least one of the terminal sections; forming a first protective layer so as to cover the top layer; forming a metal layer mainly formed of aluminum so as to cover the first protective layer; and at least partially removing the metal layer and the first protective layer to form a reflective section from the metal layer and expose only the flat area of the top surface of the top layer in the at least one of the terminal sections. Before the step of forming the first protective layer, only the flat area of the top surface of the layer is exposed in at least one of the terminal sections so as to allow the first protective layer to contact the top layer along only the flat area.
According to another aspect of the invention, a method for producing a reflection-type liquid crystal display device, including a first substrate; a second substrate; and a display medium layer interposed between the first substrate and the second substrate is provided. The first substrate includes a plurality of reflection pixel electrodes for applying a voltage to the display medium layer. The second substrate includes a counter electrode located opposed to the plurality of reflection pixel electrodes. The first substrate includes an insulating plate, and also includes, above a surface of the insulating plate opposed to the display medium layer, a plurality of thin film transistors respectively connected to the plurality of reflection pixel electrodes, a plurality of gate signal lines and a plurality of source signal lines connected to respective thin film transistors, a gate terminal section for supplying a scanning signal to the gate signal lines, a source terminal section for supplying a display signal to the source signal lines, and a common transfer terminal section for supplying a common signal to the counter electrode. The thin film transistors each include a gate electrode connected to the respective gate signal line, a source electrode connected to the respective source signal line, and a drain electrode connected to the respective reflection pixel electrode. At least one of the gate terminal section, the source terminal section and the common transfer terminal section includes a top layer formed of ITO, only a flat area of a top surface of the top layer being exposed. The method includes the steps of forming a first conductive layer on the insulating plate; patterning the first conductive layer to form the gate signal lines and the gate electrodes; forming a gate insulating layer substantially entirely on the insulating plate so as to cover at least the gate signal lines and the gate electr
Fujihara Toshiaki
Inada Kiyoshi
Kanaya Takayuki
Shiota Motoji
Nixon & Vanderhye P.C.
Parker Kenneth
Qi Mike
Sharp Kabushiki Kaisha
LandOfFree
Reflection-type liquid crystal display device, method for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Reflection-type liquid crystal display device, method for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Reflection-type liquid crystal display device, method for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2466948