U.S. patent application number 15/896143 was filed with the patent office on 2018-06-21 for liquid crystal display device.
The applicant listed for this patent is Japan Display Inc.. Invention is credited to Yuji MAEDE, Masateru MORIMOTO, Saori SUGIYAMA.
Application Number | 20180173069 15/896143 |
Document ID | / |
Family ID | 53006810 |
Filed Date | 2018-06-21 |
United States Patent
Application |
20180173069 |
Kind Code |
A1 |
SUGIYAMA; Saori ; et
al. |
June 21, 2018 |
LIQUID CRYSTAL DISPLAY DEVICE
Abstract
A liquid crystal display device in which smear error suppressed
and transmittance is uniform is provided. In a liquid crystal
display device which includes a plurality of pixels and uses
comb-teeth-shaped transparent conductive films 110 as common
wirings, the common wirings include mesh-shaped common metal
wirings 101v and 101h extending in a vertical direction and a
horizontal direction and the comb-teeth-shaped transparent
conductive films 110 are connected between adjacent pixels.
Inventors: |
SUGIYAMA; Saori; (Tokyo,
JP) ; MAEDE; Yuji; (Tokyo, JP) ; MORIMOTO;
Masateru; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Japan Display Inc. |
Tokyo |
|
JP |
|
|
Family ID: |
53006810 |
Appl. No.: |
15/896143 |
Filed: |
February 14, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15464413 |
Mar 21, 2017 |
9946131 |
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15896143 |
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15363233 |
Nov 29, 2016 |
9645462 |
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15464413 |
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15207863 |
Jul 12, 2016 |
9551908 |
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15363233 |
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15046839 |
Feb 18, 2016 |
9417490 |
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15207863 |
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14532035 |
Nov 4, 2014 |
9298048 |
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15046839 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02F 2201/121 20130101;
G02F 2001/133302 20130101; G02F 1/134336 20130101; G02F 1/133514
20130101; G02F 2201/124 20130101; G02F 2201/123 20130101; G02F
1/13439 20130101; G02F 1/1368 20130101; G02F 1/136286 20130101;
G02F 2001/136295 20130101; G02F 1/133512 20130101; G02F 1/133345
20130101; G02F 1/134363 20130101 |
International
Class: |
G02F 1/1362 20060101
G02F001/1362; G02F 1/1335 20060101 G02F001/1335; G02F 1/1333
20060101 G02F001/1333; G02F 1/1343 20060101 G02F001/1343 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 6, 2013 |
JP |
2013-230507 |
Claims
1. A display device comprising: a plurality of pixel electrodes; a
plurality of video signal lines; a plurality of scanning signal
lines; a counter electrode facing the plurality of pixel
electrodes; and a first metal wiring portion extending along one of
the video signal lines and a second metal wiring portion extending
along one of the scanning signal lines; wherein the first metal
wiring portion and the second metal wiring portion electrically
connect to the common electrode.
2. The display device according to claim 1, wherein a part of the
metal wiring contacts the counter electrode and a part of the metal
wiring does not contact the counter electrode in cross-sectional
view along an extending direction of the scanning signal line.
3. The display device according to claim 1 further comprising: an
insulating film between the counter electrode and the plurality of
video signal lines, wherein the insulating film includes formation
region on which a material of counter electrode is formed and
non-formation region on which a material of counter electrode is
not formed.
4. The display device according to claim 1, wherein the video
signal line extends while bends.
5. The display device according to claim 3, wherein the
non-formation region extends while bends along the video signal
line.
6. The display device according to claim 1, the metal wiring
extends while bends along the video signal line.
7. The display device according to claim 3, wherein the metal
wiring overlaps the non-formation region at a position overlapping
with the video signal line.
8. The display device according to claim 1, wherein the metal
wiring overlaps with the video signal line, and a width of the
metal wiring is thinner than a width of the video signal line.
9. The display device according to claim 3, wherein the material of
the counter electrode is a transparent conductive film.
10. The display device according to claim 1, wherein the counter
electrode has a first part and a second part adjacent to the first
part via the non-formation region, and the first part and the
second part are supplied same potential.
11. The display device according to claim 1, wherein an extending
length of the non-formation is greater than a total length of two
pixels.
12. The display device according to claim 1, wherein the metal
wiring having a first metal ring portion and a second metal wiring
portion, and a width of the second metal wiring potion is wider
than a width of the first metal wiring portion.
13. The display device according to claim 1, wherein the first of
the second metal wiring portion is vicinity a position where the
video signal line crosses the scanning signal line in plain view.
Description
CLAIM OF PRIORITY
[0001] The present application claims priority from Japanese patent
application JP 2013-230507 filed on Nov. 6, 2013 the content of
which is hereby incorporated by reference into this
application.
TECHNICAL FIELD
[0002] The present invention relates to a liquid crystal display
device and a manufacturing method thereof.
BACKGROUND ART
[0003] In a large screen and high resolution monitor product (the
number of pixels is about 10 M/30 inches) for broadcasting and
medical applications, wiring length becomes long and wiring
resistance becomes high, so that smear error often. occurs. This
tendency is also seen in a C-Top IPS (In-Plane Switching) type
liquid crystal display device in which common wiring formed by a
transparent conductive film (ITO) is arranged at an upper area of
pixel electrode, so that a countermeasure against smear is
performed by additionally creating horizontal common. metal wiring
having the same potential as that of the common ITO in order to
reduce common resistance, in particular, in the horizontal
direction in which the device size is large. FIG. 1A illustrates a
schematic plan view of a partial configuration of a display area of
the liquid crystal display device. Drain lines 105 that are video
signal lines are arranged in the vertical direction. An area
surrounded by the drain lines 105 and scanning signal lines
arranged in the horizontal direction forms a pixel. A large number
of common ITO wirings 110 are arranged in a pixel area. A
horizontal common metal wiring 101h is arranged in an area
(horizontal direction) overlapping the scanning signal line (gate
wiring). The liquid crystal display device is disclosed in, for
example, Japanese Unexamined Patent Application Publication. No.
2009-150952
SUMMARY OF THE INVENTION
Technical Problem
[0004] Liquid crystal display devices for monitor products tend to
have a larger screen and higher resolution. Therefore, a trial
product of a liquid crystal display device having a much larger
screen is manufactured, and then it is found that a countermeasure
of only adding horizontal common metal wirings is not sufficient to
prevent the smear error. To further reduce the common wiring
resistance, the inventors examined a structure in which vertical
common metal wirings having the same potential as that of the
common ITO are added to the horizontal common metal wirings and the
horizontal common metal wirings and the vertical common metal
wirings are arranged in a mesh pattern. FIG. 1B illustrates a
schematic plan view of a partial configuration of a display area of
this liquid crystal display device. A vertical common metal wiring
101v is arranged in an area overlapping the drain line 105, which
is a video signal line. When the metal wirings are arranged in a
mesh pattern in the vertical and horizontal directions, the common
resistance in the vertical direction can be reduced by about 10%
and the smear error is suppressed. However, it is found that the
appearance of domain areas (non-transparent areas) changes while
being driven and the transmittance changes.
[0005] An object of the present invention is to provide a liquid
crystal display device in which the smear error is suppressed and
the transmittance is uniform.
Solution to Problem
[0006] As an embodiment to achieve the above object, in a liquid
crystal display device which includes a plurality of pixels and
uses comb-teeth-shaped transparent conductive films as common
wirings,
[0007] the common wirings include mesh-shaped common metal wirings
extending in a vertical direction and a horizontal direction,
and
[0008] the comb-teeth-shaped transparent conductive films are
connected between adjacent pixels.
[0009] Further, in a liquid crystal display device which includes a
plurality of pixels and pluralities of video signal lines and
scanning signal lines, each which is connected to the plurality of
pixels, and uses comb-teeth-shaped transparent conductive films as
common wirings,
[0010] the common wirings include mesh-shaped common metal wirings
extending in a direction along the video signal lines and a
direction along the scanning signal lines, and
[0011] the comb-teeth-shaped transparent conductive films are
connected between pixels adjacent to each other with the video
signal line in between.
[0012] Further, in a liquid crystal display device which includes a
plurality of pixels and pluralities of video signal lines and
scanning signal lines, each of which is connected to the plurality
of pixels, and uses comb-teeth-shaped transparent conductive films
as common wirings,
[0013] the common wirings include mesh-shaped common metal wirings
extending in a direction along the video signal lines and a
direction along the scanning signal lines, and
[0014] the comb-teeth-shaped transparent conductive films are
connected between pixels adjacent to each other with the scanning
signal line in between.
Advantageous Effect of the Invention
[0015] According to the present invention, it is possible to
provide a liquid crystal display device in which the smear error is
suppressed and the transmittance is uniform.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1A is a schematic plan view of a main part (pixel
portion including common wirings) of a display area of a
conventional liquid crystal display device.
[0017] FIG. 1B is a plan view of a main part (common wirings) of a
liquid crystal display device examined by the inventors.
[0018] FIG. 2A is a process flow of a main manufacturing process of
a pixel portion of a liquid crystal display device according to
embodiments, which is examined by the inventors.
[0019] FIG. 2B is a process flow diagram of common wirings (in a
state in which common metal wirings are formed) of a liquid crystal
display device according to a first embodiment, which is examined
by the inventors. An upper diagram is a plan view and a lower
diagram is a cross-sectional view taken along a line A-A' in the
upper diagram.
[0020] FIG. 2C is a process flow diagram of common wirings (in a
state in which common ITO wirings are formed) of the liquid crystal
display device according to the first embodiment, which is examined
by the inventors. An upper diagram is a plan view and a lower
diagram is a cross-sectional view taken along a line B-B' in the
upper diagram.
[0021] FIG. 3A is a plan view of a main part (common wirings) of
the liquid crystal display device examined by the inventors and an
enlarged plan view of a vertical common wiring portion.
[0022] FIG. 3B is plan views of the common wiring of the liquid
crystal display device examined by the inventors. An upper diagram
illustrates a case in which a comb tooth tip is formed by ITO+metal
and a lower diagram illustrates a case in which a comb tooth tip is
formed by only ITO.
[0023] FIG. 4 is a plan view of common wirings of a liquid crystal
display device according to the first embodiment of the present
invention.
[0024] FIG. 5A is a plan view of a pixel portion of a liquid
crystal display device (normal comb-teeth-shaped common ITO
wirings) including mesh-shaped common metal wirings examined by the
inventors.
[0025] FIG. 5B is a plan view of a pixel portion of a liquid
crystal display device according to a second embodiment of the
present invention.
[0026] FIG. 5C is a plan view of a pixel portion of a liquid
crystal display device according to a third embodiment of the
present invention.
[0027] FIG. 6 is an example of a conventional monitor product and a
monitor product according to the embodiments of the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] The inventors examined a cause of the change of appearance
of the domain areas (non-transparent areas) when being driven. FIG.
2A (1) illustrates a process flow of a main manufacturing process
of a pixel area examined by the inventors. By the processes 1 to 3,
a switching thin film transistor (TFT) formed in the pixel area and
a drain line connected to the drain of the TFT are formed.
Subsequently, an inorganic passivation (PAS) film (process 4) and
an organic passivation film are formed (process 5), and then a
pixel electrode (CIT) connected to the source of the TFT is formed
(process 6). Subsequently, an upper inorganic passivation film
(UPS) is formed (process 7). Thereafter, a common metal layer and a
common ITO are formed (processes 8 and 9). It is considered that
the horizontal common metal wirings are time-proven and highly
reliable, so that attention is paid to the vertical common metal
wirings in particular.
[0029] FIGS. 3A and 3B illustrate a plan view of a main part
(common wirings) of a liquid crystal display device examined by the
inventors. An area in which a vertical area denoted by reference
numeral 140 and a horizontal area denoted by reference numeral 140
cross each other is a pixel area. A vertical common metal wiring
101v is arranged in an area overlapping the drain line 105, which
is a video signal line. FIG. 3A illustrates a case in which the
appearance of the domain area (non-transparent area) varies.
[0030] As a result of this examination, it is found that the comb
tooth tip is formed by ITO+metal in the upper diagram in FIG. 3B,
but the comb tooth tip is formed by only ITO in the lower diagram
in FIG. 3B. Therefore, the above difference is further examined. As
a result, it is found that the position, thickness, length, and tip
shape of comb of the comb tooth vary due to unevenness (variation
of etching conditions, variation of positioning, and the like) of
processing of a common ITO film, so that that is a case in which
the common ITO reaches the vertical common metal wiring 101v and a
case in which the common ITO does not reach the vertical common
metal wiring 101v. The present invention is made by the new
knowledge described above, and in the present invention, the comb
tooth of the common ITO wiring is extended and connected between
pixels adjacent to each other. Thereby, the comb tooth tip
disappears, so that even if the processing is uneven, the
positional relationship between the comb tooth tip and the common
metal does not change. Therefore, the comb tooth tip is stably
formed by ITO+metal. Thereby, it is possible to achieve uniform
transmittance while suppressing smear error. Hereinafter, the
present invention will be described using embodiments. The same
reference numerals indicate the same components.
First Embodiment
[0031] A first embodiment of the present invention will be
described with reference to FIGS. 2A to 2C and 4. Facts that are
not described in the present embodiment among results of the
examination of the inventors described above can be applied to the
present embodiment unless there are special circumstances. FIG. 2A
(1) is a process flow of a main manufacturing process of a pixel
portion of a liquid crystal display device (C-Top IPS type)
according to the present embodiment. A manufacturing method will be
described with reference to FIG. 2A (1).
<Process 1: Form Gate>
[0032] First, a gate electrode is formed on a TFT substrate formed
of glass. The gate electrode is formed in the same layer as that of
a scanning signal line. A laminate in which a Mo alloy is laminated
on an Al alloy is used for the gate electrode. However it is not
limited to this. Next, an insulating film is formed from SiN. A
portion of the insulating film, which covers the gate electrode, is
a gate insulating film.
<Process 2: Form a-Si>
[0033] Subsequently, a semiconductor layer is formed at a position
facing the gate electrode with the gate insulating film in between.
In the present embodiment, as the semiconductor layer, an a-Si film
is formed by plasma CVD. The semiconductor layer forms a channel
portion of the TFT.
<Process 3: Form Drain/Source>
[0034] Subsequently, a source electrode and a drain electrode are
formed on the semiconductor layer with the channel portion in
between. An n+Si layer is formed between the semiconductor layer
and the drain electrode or the source electrode. This is to form an
ohmic contact between the semiconductor layer and the drain
electrode or the source electrode. The drain electrode is also used
as a video signal line. The source electrode and the drain
electrode are formed in the same layer at the same time. In the
present embodiment, the source electrode or the drain electrode is
formed from a Mo alloy. When it is desired to reduce the electrical
resistance of the source electrode or the drain electrode, for
example, an electrode structure in which an Al alloy is sandwiched
by Mo alloys may be used. The names such as source and drain are
for convenience, and when one is termed as the source, the other
can be called the drain.
<Process 4: Form PAS>
[0035] Subsequently, an inorganic passivation (PAS) film is formed
from SiN to cover the TFT. The PAS film protects, in particular,
the channel portion of the TFT from impurities.
<Process 5: Form Organic PAS>
[0036] Subsequently, an organic PAS film is formed on the PAS film
and an opening from which the source electrode is exposed is formed
in a laminated film of the PAS film and the organic PAS film.
<Process 6: CIT (Form Pixel Electrode)>
[0037] Subsequently, ITO (Indium Tin Oxide), which is a pixel
electrode, is formed by sputtering to cover the laminated film of
the PAS film and the organic PAS film which includes the opening
from which the source electrode is exposed. The pixel electrode is
formed to have a planar shape.
<Process 7: Form UPS>
[0038] Subsequently, an upper inorganic passivation (UPS) film is
formed from SiN to cover the pixel electrode.
<Process 8: Form Common Metal>
[0039] Subsequently, a common metal film 101v is formed, coated
with a photoresist film, exposed, and developed, and then the
common metal film is processed. FIG. 2A illustrates a plan view of
this state and a cross-sectional view taken along a line A-A' in
the plan view. Reference numeral 105 denotes a drain line and
reference numerals 120 and 121 denote an insulating film (PAS film,
UPS film, and the like).
<Process 9: Form Common ITO>
[0040] Subsequently, ITO (Indium Tin Oxide), which is a transparent
conductive film, is formed on the entire display area by sputtering
and common ITO wirings are formed by patterning the sputtered ITO.
The common ITO wirings have a comb-teeth-shaped electrode
structure. FIG. 2C illustrates a plan view this state and a
cross-sectional view taken along a line B-B' in the plan view, and
FIG. 4 illustrates an enlarged view of the plan view. A common
metal wiring 101v is connected to a common ITO wiring 110 (FIG. 2C)
and their potentials are the same. As illustrated in FIG. 4, the
comb-teeth-shaped common ITO wirings are connected between
horizontally adjacent pixels (between pixels adjacent to each other
with a vertical common metal wiring in between) and a comb tooth
tip (pixel end portion) is formed from ITO+metal. By employing this
configuration, the tip shape of the comb tooth can be stably formed
even if the size and the position of the common wirings vary.
Thereby, the domain areas (non-transparent areas) become stable, so
that the transmittance becomes stable.
[0041] In the present embodiment, a part of upper surface and one
side surface of the common metal wiring are covered by the common
ITO wiring. However, the upper surface and both side surfaces of
the common metal wiring may be covered by the common ITO wiring.
The liquid crystal display device according to the present
embodiment can be manufactured by the process flow illustrated in
FIG. 2A (2) in this process flow, the common ITO wiring is formed
in the process 8, and the common metal wiring is formed in the
process 9.
[0042] Thereafter, the liquid crystal display device is formed by
attaching together a counter substrate in which a color filter and
a black matrix are formed and the aforementioned TFT substrate with
a liquid crystal in between.
[0043] When the liquid crystal display device is applied to a
display unit 150 of a monitor product illustrated in FIG. 6,
occurrence of the smear error can be reduced or prevented.
Reference numeral 160 denotes a frame.
[0044] As described above, according to the present embodiment, the
common wirings are formed by the common ITO wirings and the
mesh-shaped common metal wirings, and the comb-teeth-shaped common
ITO wirings are connected between adjacent pixels, so that it is
possible to provide a liquid crystal display device in which the
smear error is suppressed and the transmittance is uniform.
Second Embodiment
[0045] As illustrated in FIG. 5A, a liquid crystal display device
including normal comb-teeth-shaped common ITO wirings Forms a dual
domain in one pixel, which is an area where a vertical area denoted
by reference numeral 140 and a horizontal area denoted by reference
numeral 140 cross each other, for a countermeasure against color
shift. Therefore, a domain area (non-transparent area: light
shielding area) 130 is formed at a central portion of a pixel. The
domain area is formed by quick turn of the comb teeth at the
central portion of the pixel and causes a domain loss. A second
embodiment including avoidance of the domain loss will be described
with reference to FIG. 5B. Matters which are described in the first
embodiment but not described in the present embodiment can be
applied to the present embodiment unless there are special
circumstances.
[0046] FIG. 5B is a plan view of a pixel portion of a liquid
crystal display device according to the present embodiment and
illustrates horizontal multi-domain pixels. The structure
illustrated in FIG. 5B may be referred to as a pseudo dual domain
structure or a pseudo multi-domain structure. In the present
horizontal multi-domain pixel, regarding the common ITO wirings
extending slightly obliquely upward and the common ITO wirings
extending slightly obliquely downward, which are so far arranged in
one pixel, one set of wirings is arranged in one pixel and the
other set of wirings is arranged in a pixel immediately below
(above) the one pixel, so that a pseudo dual pixel is formed by
using two pixels. When the size of the pixels is reduced, it is
possible to reduce color shift in combination with an adjacent
pixel. Also in the present configuration, the comb-teeth-shaped
common ITO wirings are connected between horizontally adjacent
pixels (between pixels adjacent to each other with a vertical
common metal wiring in between) and a comb tooth tip is formed in
combination with a vertical common metal wiring. As the
horizontally adjacent pixels, there are a combination of a red
pixel and a green pixel, a combination of a green pixel and a blue
pixel, and a combination of a blue pixel and a red pixel. In the
present configuration, there is no domain area (non-transparent
area) in one pixel, so that it is possible to prevent the domain
loss.
[0047] When the common metal wirings are formed on the common ITO
wirings according to the process flow illustrated in FIG. 2A (2)
and a liquid crystal display device having the configuration
illustrated in FIG. 5B is manufactured and applied to the display
unit 150 of the monitor product. illustrated in FIG. 6, there is no
domain loss, and occurrence of the smear error can be reduced or
prevented. Reference numeral 160 denotes a frame.
[0048] As described above, according to the present embodiment, the
common wirings are formed by the common ITO wirings and the
mesh-shaped common metal wirings, and the comb-teeth-shaped common
ITO wirings are connected between adjacent pixels, that it is
possible to provide a liquid crystal display device in which the
smear error is suppressed and The transmittance is uniform.
Further, it is possible to prevent the domain loss by employing the
horizontal multi-domain pixels.
Third Embodiment
[0049] A third embodiment of the present invention will be
described with reference to FIG. 5C. Matters which are described in
the first and/or the second embodiments but not described in the
present embodiment can be applied to the present embodiment unless
there are special circumstances. In the first and the second
embodiments, the extending direction of the comb teeth is
approximately horizontal. However, in the present embodiment, a
case in which the extending direction of the comb teeth is
approximately vertical will be described. FIG. 5C is a plan view of
a pixel portion of a liquid crystal display device according to the
present embodiment and illustrates vertical multi-domain pixels.
The structure illustrated in FIG. 5C may be referred to as a pseudo
dual domain structure or a pseudo multi-domain structure. In the
present vertical multi-domain pixel, regarding the common ITO
wirings extending obliquely upward and the common ITO wirings
extending obliquely downward, which are so far arranged in one
pixel, one set of wirings is arranged in one pixel and the other
set of wirings is arranged in a pixel immediately below (above) the
one pixel, so that a pseudo dual pixel is formed by using two
pixels. Also in the present configuration, the comb-teeth-shaped
common ITO wirings are connected between vertically adjacent pixels
(between pixels adjacent to each other with a horizontal common
metal wiring in between) and a comb tooth tip is formed in
combination with a horizontal common metal wiring. As the
vertically adjacent pixels, there are a combination of a red pixel
and a red pixel, a combination of a green pixel and a green pixel,
and a combination of a blue pixel and a blue pixel. In the present
configuration, there is no domain area (non-transparent area) in
one pixel, so that it is possible to prevent the domain loss.
[0050] When the common metal wirings are formed on the common ITO
wirings according to the process flow illustrated in FIG. 2A (2)
and a liquid crystal display device having the configuration
illustrated in FIG. 5C is manufactured and applied to the display
unit 150 of the monitor product illustrated in FIG. 6, there is no
domain loss, and occurrence of the smear error can be reduced or
prevented. Reference numeral 160 denotes a frame.
[0051] As described above, according to the present embodiment, the
common. wirings are formed by the common ITO wirings and the
mesh-shaped common metal wirings, and the comb-teeth-shaped common
ITO wirings are connected between adjacent pixels, so that it is
possible to provide a liquid crystal display device in which the
smear error is suppressed and the transmittance is uniform.
Further, it is possible to prevent the domain loss by employing the
vertical multi-domain pixels.
[0052] The present invention is not limited to the embodiments
described above, but various modified examples are included in the
present invention. For example, the above embodiments are described
in detail in order to explain the present invention in an easily
understandable manner and are not necessarily limited to devices
that include all the components described above. Further, a part of
components of a certain embodiment can be replaced with components
of another embodiment, and components of a certain embodiment can
be added to components of another embodiment. It is possible to
perform addition/deletion/replacement of other components on a part
of components of each embodiment.
* * * * *