Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2001-09-13
2004-11-23
Tran, Minhloan (Department: 2826)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S112000, C349S110000, C349S111000, C349S118000
Reexamination Certificate
active
06822708
ABSTRACT:
RELATED APPLICATION DATA
The present application claims priority to Japanese Application(s) No(s). P2000-284292 filed Sep. 19, 2000, which application(s) is/are incorporated herein by reference to the extent permitted by law.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display device provided with a reflection electrode of a reflection diffuser panel shape formed with surface roughness and more specifically to a technique for forming an ultraviolet-reactive liquid crystal orientation film on the reflection electrode.
2. Description of the Related Art
The driving side thin film transistor (TFT) substrate of an active matrix type liquid crystal display device has, in the reflection part of a pixel, a reflection electrode of a reflection diffuser panel shape formed with surface roughness and having, in the transmission part of the pixel, a transparent electrode consisting of a transparent conductive film, thereby performing semi-transmission liquid crystal display. The driving side TFT substrate has hitherto been produced as shown in
FIGS. 12A
to
12
J.
FIGS. 12A
to
12
J show the processes for producing a liquid crystal display device having a TFT of a bottom gate construction in a pixel structure. A liquid crystal display device having a TFT of a top gate construction in a pixel structure is basically produced by the same production process.
As shown in
FIG. 12A
, a metal film is deposited on a transparent substrate
1
, and then, is dry etched using the photolithographic method to form a gate G and an auxiliary capacity electrode Cs. Thereafter, a gate insulating film
2
is laminated thereon to form a polysilicon film
3
.
To prevent impurities doping to a channel part during impurities doping to a source region and a drain region, a stopper
4
is formed on the polysilicon film
3
as the channel part so as to be in a self-alignment manner to the gate G, thereby performing impurities doping to the source region and the drain region.
Thereafter, the polysilicon fun
3
is separated in an island form using a photoresist process and an etching process to form a low-temperature polysilicon TFT.
An interlayer insulating film
5
is formed (
FIG. 12B
) To form contact holes and an opening of the transmission part of a pixel, the photoresist layer
6
is formed on the interlayer insulating film
5
. A mask with a pattern opening the contact hole forming parts the transmission part of the pixel as a photo mask is used to pattern the photoresist layer
6
by the photolithographic method (FIG.
12
C). Using this as an etching mask, the interlayer insulating film
5
is etched to form contact holes H
1
and an opening of a transmission part T of the pixel in the interlayer insulating film
5
(FIG.
12
D).
A metal film is deposited by sputtering, and then, is etched to form a source electrode S
1
and a signal wiring connected through the contact hole H
1
to the source S of a TFT and a drain electrode D
1
connected through the contact hole H
1
to the drain D of the TFT (
FIG. 12E
)
A rough shape as the underlayer of the surface roughness shape of a reflection electrode having reflection diffusion ability is formed as follows, using two layers made of a photoresist material. A first layer
7
forming a basic rough construction is formed using a photoresist material by the photolithographic method (FIG.
12
F). There is used a photo mask opening a second contact hole H
2
to be conductive with the source electrode S
1
or the drain electrode D
1
and the transmission part T of the pixel. A second layer
8
for improving the reflection properties is formed using a photoresist material similar to that of the first layer
7
by the photolithographic method (FIG.
12
F). There is used a mask, as in the first layer
7
, opening a third contact hole H
3
to be conductive with the drain electrode D
1
and the transmission part T of the pixel. A surface roughness shape consisting of two layers of the first layer
7
and the second layer
8
is thus formed.
A transparent conductive film
9
forming a transparent electrode of the transmission part T of the pixel is deposited using a sputtering method. The transparent conductive film
9
connected to the drain electrode D
1
by the contact hole H
3
(FIG.
12
H). As shown in
FIG. 12H
, the transparent conductive film
9
is formed in the reflection part of the pixel and may be used as the underlayer of the reflection electrode.
A metal film such as Al or Ag having a high reflectivity is deposited in a reflection part R of the pixel to form a reflection electrode
10
using the photolithographic method (FIG.
12
I).
A liquid crystal orientation film
30
is coated onto the entire surface of the substrate to perform an orientation process by a mechanical rubbing method (FIG.
12
J). A TFT substrate having the orientation film
30
is thus completed.
A liquid crystal orientation film is also coated onto an opposing substrate formed with a color filter and an opposing transparent electrode to perform the orientation process. Thereafter, in order that both substrates hold a suitable gap, a gap material is used to superpose both substrates together by a sealing material. Liquid crystals are then implanted in the resulting substrates for sealing to provide a liquid crystal display panel.
In the prior art method for producing the driving side TFT substrate of the active matrix type semi-transmission liquid crystal display device shown in
FIGS. 12A
to
12
J, since the orientation process is performed by the mechanical rubbing method, dust is caused during rubbing. This results in contamination of the substrate and defects due to a short circuit of the pixel electrode and the opposing electrode. Static damage due to friction is also caused. The producing yield will be lowered.
To overcome such problems, in place of the mechanical rubbing method, there is proposed an optical orientation technique in which an organic film for a liquid crystal orientation film is coated onto a substrate which is then irradiated with a polarizing ultraviolet light, so that a chemical change corresponding to the polarizing direction of the ultraviolet light is caused in the organic film to live the orientation properties and a pre-tilt angle to a liquid crystal.
As shown in
FIG. 13
, using the prior art optical orientation technique, a coating film
31
made of a composition for a liquid crystal orientation film is formed on the reflection electrode
10
of a reflection diffuser panel shape formed with surface roughness, and then, is radiated with a polarizing ultraviolet light L
0
. Incident angles &agr;
1
and &agr;
2
of the polarizing ultraviolet light L
0
to the coating film
31
are not constant depending on a position on the surface roughness. A predetermined pre-tilt angle cannot be obtained. The polarizing ultraviolet light L
0
passing through the coating film
31
made of a composition for a liquid crystal polarization film is reflected by the reflection electrode
10
. A reflection light L
1
thereof is irradiated again onto the coating film
31
(a re-irradiation phenomenon). A predetermined orientation process cannot be performed. The display quality is lowered significantly.
The liquid crystal orientation film is formed on the reflection electrode of a reflection diffuser panel shape formed with surface roughness. Similar problems are caused not only in the semi-transmission liquid crystal display device having in one pixel a reflection part formed with a reflection electrode and a transmission part made of a transparent conductive film, but also in a reflection type liquid crystal display device having a pixel electrode consisting only of a reflection electrode. They are also caused not only in the active matrix type liquid crystal display device but also in a passive type liquid crystal display device.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a liquid crystal display device having a reflection electrode of a reflection diffuser panel shape forme
Erdem Fazli
Sonnenschein Nath & Rosenthal LLP
Sony Corporation
Tran Minhloan
LandOfFree
Liquid crystal display device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Liquid crystal display device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Liquid crystal display device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3350169