Active solid-state devices (e.g. – transistors – solid-state diode – Non-single crystal – or recrystallized – semiconductor... – Amorphous semiconductor material
Reexamination Certificate
1999-07-09
2001-04-17
Abraham, Fetsum (Department: 2811)
Active solid-state devices (e.g., transistors, solid-state diode
Non-single crystal, or recrystallized, semiconductor...
Amorphous semiconductor material
C257S072000, C349S088000, C349S187000, C349S183000, C349S110000, C349S111000
Reexamination Certificate
active
06218679
ABSTRACT:
BACKGROUND OF THE INVENTION
1. (Field of the Invention)
The present invention relates to a liquid crystal display panel utilizable as a touch panel or for the display of televised images, a projection type display device utilizing the liquid crystal display panel as a light valve for the display of images in the form as projected onto a screen, and a viewfinder utilizing the liquid crystal display panel as a display monitor for monitoring images being videoed.
2. (Description of the Prior Art)
The liquid crystal display panel is known to be light-weight and thin in thickness as compared with a cathode ray tube and a variety of liquid crystal display panels have been developed. Recent application of the liquid crystal panel is a display unit in pocketable television receiver sets and a display unit in viewfinders of video cameras. However, the liquid crystal display panel has difficulty in securing a relatively large display format and, therefore, a compromise has been made to incorporate the liquid crystal panel in a projection type display device of a type employing an optical system for projecting images generated by the liquid crystal panel onto a screen. The projection type display device and the viewfinder both currently placed in the market make use of a twisted nematic (TN) liquid crystal display panel which utilizes a rotatory polarization of the liquid crystal.
The prior art liquid crystal display panel will be discussed in detail with reference to the accompanying drawings which illustrate it only for illustration purpose.
FIG. 60
illustrates a fragmentary sectional view of the prior art liquid crystal display panel. The prior art liquid crystal display panel makes use of a layer of TN liquid crystal
383
filled and sealed between an array substrate
12
, formed with thin-film transistors
14
and others, and a counter substrate
11
spaced a distance of 4 to 6 &mgr;m from the array substrate
12
. A peripheral region of the TN liquid crystal display panel outside a display region is sealed by the use of sealing resin (not shown). Reference numeral
381
represents a black matrix formed of metallic material such as chromium; reference numeral
13
represents a counter electrode made of transparent material such as ITO; reference numeral
15
represents pixel electrodes; and reference numerals
382
a
and
382
b
represent orientation films.
The orientation films
382
a
and
382
b
are formed so as to overlay the pixel electrodes
15
and the counter electrode
13
and are subjected to a rubbing treatment to orient liquid crystal molecules of the liquid crystal layer
383
. A polarizing plates
384
a
and
384
b
are lined to each of the counter substrate
11
and the array substrate
12
respectively.
The prior art TN liquid crystal display panel discussed above is manufactured in the following manner. Each of the array substrate
12
and the counter substrate
11
is lined with an orientation film
382
a
and
382
b
which is subsequently rubbed for alignment treatment. Then, a peripheral region of the array substrate
12
is deposited with a sealing resin (not shown) leaving an injection port for subsequent injection of a quantity of TN liquid crystal material
383
. On the other hand, beads of transparent glass or synthetic resin are distributed over the counter substrate
11
so that a uniform thickness of the TN liquid crystal layer can be formed. Thereafter, the counter substrate
11
and the array substrate
12
are joined together, followed by heating of the sealing resin to cure the latter to thereby firmly bond the substrates
11
and
12
together. The assembly of the substrates
11
and
12
bonded together is placed in a vacuum chamber to evacuate the space between the array substrate
12
and the counter substrate
11
, followed by immersion of the assembly into a bath of TN liquid crystal material. When the vacuum in the chamber is released, the TN liquid crystal material is sucked into the space between the substrates
11
and
12
through the injection port, followed by sealing of the injection port to thereby complete the liquid crystal display panel.
FIG. 15A
illustrates a plan view of a display panel module in which the liquid crystal display panel is fixedly mounted on a chassis and
FIG. 15B
illustrates a cross-sectional view taken along the line
15
B—
15
B in
FIG. 15A. A
chassis
161
in the form of a stainless metallic plate has a printed circuit board
162
mounted thereon. The printed circuit board
162
has a connector
163
, electrolytic capacitors and others mounted thereon and also has a number of copper conductors (not shown) formed thereon by the use of a circuit printing technique for transmission of electric signals from the connector
163
. The printed circuit board
162
has a central region perforated, and the TN liquid crystal display panel is mounted on the printed circuit board
162
with the display region thereof aligned with the central perforation defined in the printed circuit board
162
. The TN liquid crystal display panel has thin-film conductors formed therein for transmission of the electric signals. The copper conductors are connected at one end with the associated thin-film conductors by means of fine wires (bonding wires) made of aluminum.
The peripheral region of the TN liquid crystal display panel outside the display region thereof is formed with a generally square ring-shaped light shielding pattern
164
which is indicated by dotted lines in FIG.
15
A. Cross-sectional representations of the light shielding pattern
164
taken along the lines corresponding to lines
16
A—
16
A and
16
B—
16
B in
FIG. 15A
are shown in
FIGS. 61A and 61B
, respectively. The light shielding pattern
164
made of chromium and having a film thickness of about 1,000 angstrom is formed over the counter electrode
13
on the counter substrate
11
. Reference numeral
21
represents source signal lines.
The reason for formation of the light shielding pattern
164
and the black matrix with the use of chromium is because a relatively small film thickness can be obtained with an increased light shielding effect. The TN liquid crystal display panel requires an orientation treatment to be effected to the orientation films
382
to align the liquid crystal molecules. The orientation treatment is carried out by rubbing the pixel electrodes
15
. If the black matrix
381
has a relatively great film thickness, it gives rise to considerable surface irregularities on each of the substrates
11
and
12
and a favorable orientation treatment can no longer be effected.
The reason for the formation of the light shielding pattern
164
in the peripheral region of the TN liquid crystal display panel outside the display region will now be described briefly. The peripheral region of the TN liquid crystal display panel outside the display region has no pixel, but is formed with the source signal lines
21
for transmission of electric signals to the display region. Since the source signal lines
21
are in the form of a metallic thin film, they shield light off. However, light incident upon a gap between one source signal line and the neighboring source signal line is allowed to pass therethrough since no light shielding element exist in that gap. Passage of light through the display region of the TN liquid crystal display panel suffices, and light transmitted from somewhere other than the display region of the TN liquid crystal display panel is of no use and may constitute a cause of darkening of images being displayed. The light transmitted from somewhere other than the display region of the TN liquid crystal display panel is shielded by the chassis
161
. Since the chassis
161
is in the form of a stainless metallic plate, no light passes therethrough. The chassis
161
is perforated at a central area thereof which is positioned so as to align with the perforation in the printed circuit board and the display region of the TN liquid crystal display panel.
Although the TN liquid crystal display panel has dimensions highly precisely tailored
Sannohe Shinya
Takahara Hiroshi
Abraham Fetsum
Matsushita Electric - Industrial Co., Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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