U.S. patent application number 13/415378 was filed with the patent office on 2012-09-13 for electro-optical device and electronic apparatus.
This patent application is currently assigned to SEIKO EPSON CORPORATION. Invention is credited to Shin FUJITA.
Application Number | 20120229438 13/415378 |
Document ID | / |
Family ID | 45976078 |
Filed Date | 2012-09-13 |
United States Patent
Application |
20120229438 |
Kind Code |
A1 |
FUJITA; Shin |
September 13, 2012 |
ELECTRO-OPTICAL DEVICE AND ELECTRONIC APPARATUS
Abstract
An electro-optical device includes a scanning line, a data line
intersecting with each other, a pixel circuit which is provided
corresponding to the intersection thereof, and a wire. The pixel
circuit includes a light emitting element, one transistor which
controls a current flowing to the light emitting element, and the
other transistor of which conduction state is controlled according
to a scanning signal which is supplied to the scanning line between
a gate node of the one transistor and the data line. The wire is
provided between the data line and the one transistor.
Inventors: |
FUJITA; Shin; (Suwa-shi,
JP) |
Assignee: |
SEIKO EPSON CORPORATION
Tokyo
JP
|
Family ID: |
45976078 |
Appl. No.: |
13/415378 |
Filed: |
March 8, 2012 |
Current U.S.
Class: |
345/211 |
Current CPC
Class: |
G09G 2320/0209 20130101;
H01L 27/3276 20130101; G09G 3/3283 20130101; G09G 2300/043
20130101; H01L 27/3272 20130101; G09G 2300/0809 20130101; G09G
2330/06 20130101; H01L 27/3262 20130101; H01L 27/124 20130101; G09G
3/3266 20130101; G09G 2300/0426 20130101; H01L 27/3265 20130101;
H01L 27/1255 20130101; G09G 3/3233 20130101 |
Class at
Publication: |
345/211 |
International
Class: |
G09G 5/00 20060101
G09G005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 10, 2011 |
JP |
2011-053562 |
Claims
1-20. (canceled)
21. An electro-optical device comprising: a scanning line; a data
line which intersects the scanning line; a wire applied with a
constant potential; a light emitting element; a driving transistor
that controls a current flowing through the light emitting element,
the driving transistor having a first end coupled to the light
emitting element and a second end; a switching transistor which is
coupled between the gate of the driving transistor and the data
line, and of which conduction state is controlled according to a
scanning signal which is supplied through the scanning line; and a
holding capacitor having a first electrode coupled to the first end
of the driving transistor, the wire overlapping at least a part of
the first electrode of the holding capacitor in plan view.
22. The electro-optical device according to claim 21, the driving
transistor being an N-channel-type transistor.
23. The electro-optical device according to claim 21, the holding
capacitor coupled between the first end of the driving transistor
and the gate of the driving transistor.
24. The electro-optical device according to claim 21, the wire
being provided between the driving transistor and the data line in
a cross-sectional view.
25. The electro-optical device according to claim 21, a distance
between the wire and the data line being shorter than a distance
between the wire and the driving transistor.
26. The electro-optical device according to claim 21, further
comprising a first power line and a second power line, the light
emitting element and the driving transistor being coupled to each
other in series in a path between the first power line and the
second power line, and the wire being coupled to one of the first
power line and the second power line.
27. The electro-optical device according to claim 26, the wire
having a portion which is coupled to the one of the first power
line and the second power line.
28. The electro-optical device according to claim 21, the wire
being parallel with the data line.
29. The electro-optical device according to claim 21, further
comprising another wire and another data line immediately adjacent
to the data line, the other wire being provided between the driving
transistor and the other data line, the data line and the other
data line being provided on opposite sides of the driving
transistor in plan view.
30. The electro-optical device according to claim 21, the wire
overlapping the first end of the driving transistor in plan
view.
31. The electro-optical device according to claim 21, the wire
having a shield function.
32. The electro-optical device according to claim 21, the wire
decreasing influences of a noise on a potential of the first
electrode of the holding capacitor, the noise being caused by a
potential fluctuation of the data line.
33. The electro-optical device according to claim 21, further
comprising a relay electrode coupled to the first end of the
driving transistor and the light emitting element, the wire having
an opening, the relay electrode provided in the opening of the
wire.
34. An electro-optical device comprising: a scanning line; a data
line which intersects the scanning line; a wire applied with a
constant potential; a light emitting element; a driving transistor
that controls a current flowing through the light emitting element,
the driving transistor having a first end coupled to the light
emitting element and a second end; and a switching transistor which
is coupled between the gate of the driving transistor and the data
line, and of which conduction state is controlled according to a
scanning signal which is supplied through the scanning line, the
wire overlapping the first end of the driving transistor in plan
view.
35. An electronic apparatus comprising an electro-optical device
according to claim 21.
36. An electronic apparatus comprising an electro-optical device
according to claim 22.
37. An electronic apparatus comprising an electro-optical device
according to claim 23.
38. An electronic apparatus comprising an electro-optical device
according to claim 24.
39. An electronic apparatus comprising an electro-optical device
according to claim 25.
40. An electronic apparatus comprising an electro-optical device
according to claim 26.
Description
[0001] This application claims priority to JP 2011-053562 filed
Mar. 10, 2011, the disclosure of which is hereby incorporated by
reference herein in its entirety.
BACKGROUND
[0002] 1. Technical Field
[0003] The present invention relates to an electro-optical device
and an electronic apparatus.
[0004] 2. Related Art
[0005] In recent years, various electro-optical devices in which a
light emitting element such as an Organic Light Emitting Diode
(hereinafter, referred to as "OLED") is used have been proposed. In
such an electro-optical device, a pixel circuit is provided
corresponding to the intersection of a scanning line and a data
line. In general, the pixel circuit includes the above described
light emitting element, a switching transistor, and a driving
transistor (refer to JP-A-2007-310311). Here, the switching
transistor is turned on in a selection period of the scanning line,
between the data line and a gate of the driving transistor, and in
this manner, an electric potential which is supplied to the data
line is held in the gate. In addition, the driving transistor is
configured to flow a current corresponding to a holding potential
of the gate to the light emitting element.
[0006] Meanwhile, in a usage in which miniaturization of the size
of a display and higher resolution of the display are necessary,
the data line and the driving transistor are close to each other,
and the degree of capacitative coupling is increased. For this
reason, when there is potential fluctuation of the data line, the
potential fluctuation propagates to each portion of the driving
transistor, especially to the gate as a kind of noise, through
parasitic capacitance, and causes the holding potential of the gate
to fluctuate. Accordingly, there was a problem in that the display
quality is degraded, since it was not possible to flow a desired
current to the light emitting element.
SUMMARY
[0007] An advantage of some aspects of the invention is to prevent
the display quality from being degraded due to noise which is
caused by the potential fluctuation of the data line.
[0008] According to an aspect of the invention, there is provided
an electro-optical device which includes, scanning lines and data
lines which intersect with each other; pixel circuits which are
provided corresponding to the intersection of the scanning lines
and the data lines; and a shield wires, wherein each of the pixel
circuit includes a light emitting element, a driving transistor
which controls a current flowing to the light emitting element, and
a switching transistor which is connected between a gate of the
driving transistor and the data line, and of which conduction state
is controlled according to a scanning signal which is supplied to
the scanning line, and wherein each of the shield wires is provided
between the data line and the driving transistor when seen in the
plan view.
[0009] According to the aspect of the invention, the noise which is
generated from the data line is absorbed by the shield wire before
reaching the driving transistor of the pixel circuit. For this
reason, the driving transistor is hardly influenced by noise or the
like, therefore, it is possible to prevent the display quality from
being degraded.
[0010] According to the aspect of the invention, it is preferable
that the distance between the shield wire and the data line be
shorter than the distance between the shield wire and the driving
transistor. According to the aspect, it is possible to more
reliably suppress the influence by the noise or the like.
[0011] According to the aspect of the invention, regarding the
shield wire, even if it is in a high impedance state (floating)
which is not electrically connected to a certain portion, it is
possible to absorb the noise, for example, when capacitative
coupling is performed to a electric supply line of a constant
potential in time, however, it is preferable that be directly
connected to the constant potential in time. In this configuration,
in the pixel circuit, the light emitting element and the driving
transistor are connected to each other in series in a path between
the power line on the high side and the power line on the low side,
and if the shield wire is connected to the high side power line, or
to the low side power line, it is sufficient if it is connected to
an existing power line.
[0012] In addition, in such a configuration, in the pixel circuit,
if the shield wire has a portion which is connected to the high
side power line or the low side power line, it is possible to more
reliably absorb the noise, since the shield wire can be made to
have low impedance.
[0013] Further, according to the aspect of the invention, it is
preferable to have a holding capacity of which one end is
electrically connected to the gate of the driving transistor. In
this configuration, if the shield wire is set to cover the holding
capacity when seen in the plan view, it is possible to make a
holding voltage due to the holding capacity difficult to be
influenced by noise.
[0014] In addition, according to another aspect of the invention,
there is provided an electro-optical device which includes,
scanning lines and data lines which intersect with each other;
pixel circuits which are provided corresponding to each the
intersection of the scanning lines and the data lines; and shield
wires, wherein each of the pixel circuit includes a light emitting
element, a driving transistor which controls a current flowing to
the light emitting element, and a switching transistor which is
connected between a gate of the driving transistor and the data
line, and of which conduction state is controlled according to a
scanning signal which is supplied to the scanning line, and wherein
the shield wire is provided between the data line and the driving
transistor in the cross-sectional view, and may be obtained by a
configuration in which the shield wire is overlapped with at least
a part of the data line or the driving transistor when seen in the
plan view.
[0015] In addition, the electro-optical device according to the
aspect of the invention may be applied to various electronic
apparatuses. Typically, they are display devices, and as an
electronic apparatus, for example, there is a personal computer or
a mobile phone. Especially, in the application, even when the
holding capacity is not sufficiently secure, the noise from the
data line is absorbed to the shield wire before reaching the
driving transistor of the pixel circuit, and due to this, it is
possible to prevent the quality of the display from being degraded.
Accordingly, for example, it is preferable to be applied to a
display device which forms a reduced image such as a display device
for a head-mounted display or a projector. The usage of the
electro-optical device according to the aspect of the invention is
not limited to the display device. For example, it may be applied
to an exposure device (optical head), as well, which forms a latent
image on an image carrier such as a photoconductive drum by
irradiating a light beam.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The invention will be described with reference to the
accompanying drawings, wherein like numbers reference like
elements.
[0017] FIG. 1 is a block diagram which shows a configuration of an
electro-optical device according to a first embodiment of the
invention.
[0018] FIG. 2 is a diagram which shows an equivalent circuit of a
pixel circuit in the electro-optical device.
[0019] FIG. 3 is a diagram which shows a display operation of the
electro-optical device.
[0020] FIG. 4 is a plan view which shows a configuration of the
pixel circuit.
[0021] FIG. 5 is a partial cross-sectional view which shows the
configuration in FIG. 4 which is cut along line V-V.
[0022] FIG. 6 is a diagram which shows absorption of noise from a
data line in the pixel circuit.
[0023] FIG. 7 is a diagram which shows a variety of parasitic
capacitances in the pixel circuit.
[0024] FIG. 8 is a diagram in which the variety of parasitic
capacitances in the pixel circuit are modeled.
[0025] FIGS. 9A and 9B are diagrams which show an example of
crosstalk.
[0026] FIG. 10 is a plan view which shows a configuration of a
pixel circuit of an electro-optical device according to a second
embodiment of the invention.
[0027] FIG. 11 is a partial cross-sectional view which shows the
configuration in FIG. 10 which is cut along line XI-XI.
[0028] FIG. 12 is a plan view which shows a configuration of a
pixel circuit of an electro-optical device according to a third
embodiment of the invention.
[0029] FIG. 13 is a partial cross-sectional view which shows the
configuration in FIG. 12 which is cut along line XIII-XIII.
[0030] FIG. 14 is a plan view which shows a configuration of a
pixel circuit of an electro-optical device according to a fourth
embodiment of the invention.
[0031] FIG. 15 is a plan view which shows a configuration of a
pixel circuit of an electro-optical device according to a fifth
embodiment of the invention.
[0032] FIG. 16 is a plan view which shows a configuration of a
pixel circuit of an electro-optical device according to a sixth
embodiment of the invention.
[0033] FIG. 17 is a partial cross-sectional view which shows the
configuration in FIG. 16 which is cut along line XVII-XVII.
[0034] FIG. 18 is a plan view which shows a configuration of a
pixel circuit of an electro-optical device according to a seventh
embodiment of the invention.
[0035] FIG. 19 is a diagram which shows an equivalent circuit of a
pixel circuit according to a different example.
[0036] FIG. 20 is a diagram which shows an electronic apparatus
(the one) to which the electro-optical device is applied.
[0037] FIG. 21 is a diagram which shows an electronic apparatus
(the two) to which the electro-optical device is applied.
[0038] FIG. 22 is a diagram which shows an electronic apparatus
(the three) to which the electro-optical device is applied.
DETAILED DESCRIPTION OF EMBODIMENTS
First Embodiment
[0039] FIG. 1 is a block diagram which shows a configuration of an
electro-optical device according to a first embodiment of the
invention. The electro-optical device 1 is a device for displaying
an image using a plurality of pixel circuits 110.
[0040] As shown in the drawing, the electro-optical device 1
includes an element unit 100, a scanning line driving circuit 210
and a data line driving circuit 220.
[0041] Among these, in the element unit 100, m rows of scanning
lines 112 are provided in the row (X) direction, and n columns of
data lines 114 are provided in the column (Y) direction in the
drawing so as to maintain electrical insulation with respect to
each of the scanning lines 112, each other. The pixel circuit 110
is respectively arranged corresponding to each intersection between
the m rows of scantling lines 112 and the n columns of data lines
114. Accordingly, in the embodiment, the pixel circuit 110 is
arranged in matrix of vertical m rows x horizontal n columns. In
addition the number m and n are all natural numbers.
[0042] Respective power lines 116 are commonly connected to each of
the pixel circuits 110, and a potential Vel on the high side of
device power is supplied thereto. In addition, although omitted in
FIG. 1, as will be described later, a common electrode is provided
over each of the pixel circuits 110, and a potential Vct on the low
side of the device power is supplied thereto. These potentials Vel
and Vct are generated by a power supply circuit which is not
shown.
[0043] In addition, in order to distinguish the row of the scanning
line 112 from the row of the pixel circuit 110 conveniently, there
may be a case where the rows are called sequentially from above a
first row, a second row, a third row, . . . , (m-1)th row, and mth
row in FIG. 1. Similarly, in order to conveniently distinguish the
column of the data line 114 from the column of the pixel circuit
110, there may be a case where the columns are called sequentially
from above a first column, a second column, a third column, . . . ,
(n-1)th column and nth column in FIG. 1.
[0044] In the electro-optical device 1, the scanning line driving
circuit 210 and the data line driving circuit 220 are arranged in
the vicinity of a region where the pixel circuits 110 are arranged
in matrix. The operations of the scanning line driving circuit 210
and the data line driving circuit 220 are controlled by a
controller which is not shown. In addition, gray scale data which
designates gray scale (brightness) to be expressed in each of the
pixel circuits 110 is supplied to the data driving circuit 220 from
the controller.
[0045] The scanning line driving circuit 210 is a circuit which
sequentially selects the row of scanning lines 1 to m in each
frame. For example, the scanning line driving circuit 210 is the
circuit which supplies respective scanning signals of Gwr (1), Gwr
(2), Gwr (3), . . . , Gwr (m-1), Gwr(m) to the scanning lines of
the first row, the second row, the third row, . . . , (m-1)th row,
and mth row, and sequentially sets each of the scanning lines in
the frame to H level, exclusively. In this description, the frame
means the time period which is necessary to display an image of one
cut (frame) in the electro-optical device 1, and if the vertical
scan frequency is 60 Hz, it is a time period of 16.67 milliseconds
of one cycle thereof.
[0046] The data line driving circuit 220 is a circuit which
supplies a data signal of a potential corresponding to the gray
scale data of the pixel circuit 110, with respect to the pixel
circuit 110 which is positioned on a row which is selected by the
scanning line driving circuit 210, through the data line 114. For
the sake of convenience, the data signals which are respectively
supplied to the data lines 114 of the first column, a second
column, a third column, . . . , (n-1)th column and nth column are
denoted by Vd (1), Vd (2), Vd (3), . . . , Vd (n-1), and Vd
(n).
[0047] Subsequently, the equivalent circuit of the pixel circuit
110 will be described with reference to FIG. 2. In addition, in
FIG. 2, pixel circuits 110 are shown arranged 2.times.2 for a total
of four pixels, which corresponds to intersections of the scanning
lines 112 of ith row and (i+1)th row which neighbors the ith row
from below, and the data lines 114 of jth column and (j+1)th column
which neighbors the jth column on the right. Here, the i and (i+1)
are symbols which are used when generally showing the columns in
which the pixel circuits 110 are arranged, and the symbols are
integers of equal to 1 or more and equal to n or less. Similarly,
the j and (j+1) are symbols which are used when generally showing
the columns in which the pixel circuits 110 are arranged, and the
symbols are integers of equal to 1 or more and equal to n or
less.
[0048] As shown in FIG. 2, each pixel circuit 110 includes
transistors 130 and 140 of N-channel-type, a holding capacity 135,
and a light emitting element 150. Since each of the pixel circuits
110 has the same configuration as each other, the pixel circuit on
the ith row and the jth column will be representatively described.
In the pixel circuit on the ith row and the jth column, the
transistor 130 functions as a switching transistor, and a gate node
thereof is connected to the scanning line 112 on the ith row. On
the other hand, a drain node thereof is connected to the data line
114 on the jth column, and a source node thereof is connected to
one end of the holding capacity 135, and to a gate node of the
transistor 140, respectively.
[0049] The other end of the holding capacity 135 is connected to a
source node of the transistor 140 and an anode of the light
emitting element 150, respectively. On the other hand, a drain node
of the transistor 140 is connected to the power supply line
116.
[0050] For the sake of convenience, in the pixel circuit 110 of ith
row and jth column, the drain node of the transistor 130 is denoted
by a capital letter of D, the gate node of the transistor 140 (a
source node of the transistor 130 and one end of the holding
capacity 135) is denoted by a small letter g. Particularly, the
gate node of the transistor 140 on the ith row and jth column is
denoted by g(i, j).
[0051] In addition, the drain node (power supply line 116) of the
transistor 140 is denoted by a small letter d, and a source node of
the transistor 140 (an anode of the light emitting element 150) is
denoted by a small letter s.
[0052] The cathode of the light emitting element 150 is connected
to a common electrode 118 in each of the pixel circuits 100. The
common electrode 118 is common to the light emitting element 150 of
each pixel circuit 110. The light emitting element 150 is an OLED
which interposes a light-emitting layer which is formed of an
organic EL material, between the anode and cathode which face each
other. The light emitting element emits light with a brightness
which corresponds to a current which flows from the anode toward
the cathode.
[0053] In addition, in FIG. 2, Gwr (i) and Gwr (i+1) denote
scanning signals which are respectively supplied to scanning lines
112 of ith row and (i+1)th row. Further, Vd (j) and Vd (j+1) denote
data signals which are respectively supplied to data lines 114 of
jth column and (j+1)th column.
[0054] In addition, according to the embodiment, a shield wire is
provided in the vicinity of the data line 114, however, the shield
wire will be described in detail later.
[0055] Subsequently, a display operation of the electro-optical
device 1 will be simply described with reference to FIG. 3. FIG. 3
is a diagram which shows an example of a waveform of the scanning
signal and the data signal.
[0056] As shown in the drawing, the scanning signals Gwr (1), Gwr
(2), Gwr(3), Gwr (m-1), and Gwr(m) are sequentially set to (H)
level exclusively, for every horizontal scanning period (H) in each
frame by the scanning line driving circuit 210.
[0057] Here, when the ith row scanning line 112 is selected, and
the scanning signal Gwr (i) is set to (H) level, a data signal Vd
(j) of a potential which corresponds to gray scale data of the
pixel circuit 110 on the ith row and jth column is supplied by the
data line driving circuit 220 in the date line 114 on the jth
column.
[0058] When the scanning signal Gwr (i) is set to H level in the
pixel circuit 110 on the ith row and jth column, since the
transistor 130 is turned on, the gate node g (i, j) is electrically
connected to the data line 114 on the jth column. For this reason,
the potential of the gate node g (i, j) becomes the potential of
data signal Vd (j) as denoted by an up arrow in FIG. 3. At this
moment, the transistor 140 flows a current which corresponds to the
current of the gate node g (i, j) to the light emitting element
150, and the holding capacity 135 holds a voltage between the gate
and source in the transistor 140 at this moment. When the selection
of the scanning line 112 on the ith row is ended, and the scanning
signal Gwr (i) becomes L level, the transistor 130 is turned
off.
[0059] Even if the transistor 130 is turned off from the on state,
the voltage of the transistor 140 between the gate node and the
source node when the transistor 130 is turned on is held by the
holding capacity 135. For this reason, even if the transistor 130
is turned off, the transistor 140 continuously flows a current
corresponding to the hold voltage by the holding capacity 135 to
the light emitting element 150, until the next scanning line 112 on
the ith row is selected again. For this reason, the light emitting
element 150 in the pixel circuit 110 on the ith row and jth column
continuously emits light during the period corresponding to one
frame with a brightness corresponding to a potential of data signal
Vd (j) at the time of selecting the ith row, that is, with a
brightness corresponding to the gray scale data of the ith row and
jth column.
[0060] In addition, in the ith row, the light emitting element emit
lights with a brightness corresponding to a potential of a data
signal which has been supplied to the corresponding data line 114,
even in a pixel circuit 110 other than the jth column. Further, a
pixel circuit 110 corresponding to the scanning line 112 on the ith
row is described here, however, the scanning line 112 is selected
in order of the first row, the second row, the third row, . . . ,
the (m-1)th row, and the mth row. As a result, each of the pixel
circuits 110 emits light with a brightness corresponding to the
gray scale data, respectively. Such an operation is repeated for
every frame.
[0061] In addition, in FIG. 3, potential scales of the data signal
Vd (j) and the gate node g (i, j) are conveniently enlarged,
compared to a potential scale of the scanning signal.
[0062] Meanwhile, since the data signal has a potential
corresponding to the gray scale data of a pixel which is positioned
on the selected row, the data line 114 is subject to potential
fluctuation every second according to the display content. For
example, since the data signal Vd (j) as shown in FIG. 3 is
supplied to the data line 114 on the jth column, the potential
fluctuates for every horizontal scanning period (H).
[0063] When the data line 114 performs capacitative coupling with
each part of the pixel circuit 110, the potential fluctuation of
the data line 114 has a negative influence on the potential of each
part of the pixel circuit 110. Particularly, when a smaller size
and higher resolution of the display is required, and for example,
in a micro display for which the display size is less than one inch
in diagonal, and the resolution is 1280.times.720 pixels or more,
the negative influence is prominent, since the parasitic
capacitance of each part is relatively large compared to the
holding capacity 135. Particularly, the potential of the gate node
g and source node s of the transistor 140 define a current which
flows to the light emitting element 150, the potential fluctuation
of this part generates a garbled display or crosstalk which will be
described later, and causes a serious degradation of a display
quality.
[0064] Therefore, according to the embodiment, the pixel circuit
110 is configured as follows, and it is difficult to be influenced
by noise due to the potential fluctuation of the data line.
[0065] The structure of the pixel circuit 110 will be described
with reference to FIGS. 4 and 5.
[0066] FIG. 4 is a plan view which shows a configuration of four
pixel circuits 110 which are close to each other in the vertical
and horizontal directions. FIG. 5 is a partial cross-sectional view
of the pixel circuit in FIG. 4 which is cut along line V-V.
[0067] In addition, FIG. 4 shows a wiring structure of the pixel
circuits 110 of a top emission-type when seen in the plan view from
the viewer side, however, for simplicity, a structure which is
formed after the pixel electrode (anode) in the light emitting
element 150 is omitted. In FIG. 5, structures up to the pixel
electrode of the light emitting element 150 are shown, and the
structures thereafter are not shown. In addition, hereinafter, in
each drawing, reduced scales of each layer, each member, each
region, or the like are differentiated in order to set to a
recognizable size.
[0068] First, as shown in FIG. 5, a substrate 2 as a base is
provided with respective semiconductor layers 130a and 140a on
which a polysilicon film is patterned in a shape of an island. The
semiconductor layer 130a forms the transistor 130, and the
semiconductor layer 140a forms the transistor 140. Here, the
semiconductor layer 130a is formed in a shape of a rectangle of
which straight side horizontally extends along the scanning line
112 which will be formed later, as shown in FIG. 4 when seen in the
plan view. On the other hand, the semiconductor layer 140a is
formed in the shape of a rectangle of which straight side
horizontally extends along the data line 114 which will be formed
later, when seen in the plan view.
[0069] As shown in FIG. 5, a gate insulating layer 10 is provided
so as to substantially cover the entire surface of the
semiconductor layer 130a and the semiconductor layer 140a. A gate
wiring layer of aluminum or tantalum is provided on the front
surface of the gate insulating layer 10, and the respective
scanning line 112 and gate electrode layer 21 are provided by
patterning the gate wiring layer.
[0070] The scanning line 112 extends in the horizontal direction in
FIG. 4, has a branched portion toward the downward direction for
every pixel circuit 110, and the branched portion thereof is
overlapped with the center portion of the semiconductor layer 130a.
Among the semiconductor layers 130a, the region which overlaps with
the branched portion of the scanning line 112 is the channel region
130c (refer to FIG. 5). In addition, in FIG. 5, in the
semiconductor layers 130a, the left side is the drain region 130d,
and the right side is the source region 130s with respect to the
channel region 130c.
[0071] On the other hand, the gate electrode layer 21 has a shape
of a rectangular frame in which the upper side, the right side, and
the lower side are integrated without having a left side, as shown
in FIG. 4 when seen in the plan view. Among these, the lower side
is overlapped with the center portion of the semiconductor layer
140a. Among the semiconductor layers 140a, a region which is
overlapped with the lower side of the gate electrode layer 21
becomes the channel region 140c (refer to FIG. 5). In the
semiconductor layer 140a, in FIG. 5, the left side is the drain
region 140d, and the right side is the source region 140s with
respect to the channel region 140c.
[0072] In FIG. 5, a first interlayer insulating layer 11 is formed
so as to cover the scanning line 112, the gate electrode layer 21
or the gate insulating layer 10. A conductive wiring layer is
formed, and relay electrodes 41, 42, 43, and 44 are respectively
formed on the front surface of the first interlayer insulating
layer 11.
[0073] Among these, the relay electrode 41 is connected to the
drain region 130d through a contact (via) hole 31 which
respectively opens the first interlayer insulating layer 11 and the
gate insulating layer 10.
[0074] In addition, in FIG. 4, a portion where an "x" mark is
applied to the ".quadrature." mark is a contact hole.
[0075] In FIG. 5, one end of the relay electrode 42 is connected to
the source region 130s through a contact hole 32 which respectively
opens the first interlayer insulating layer 11 and the gate
insulating layer 10. On the other hand, the other end of the relay
electrode 42 is connected to the gate electrode layer 21 through a
contact hole 33 which opens the first interlayer insulating layer
11.
[0076] The relay electrode 43 is connected to the source region
140s through a contact hole 34 which respectively opens the first
interlayer insulating layer 11 and the gate insulating layer 10.
Here, the shape of the relay electrode 43 when seen in the plan
view is a rectangle so as to cover the upper side of the gate
electrode layer 21 as shown in FIG. 4. For this reason, the holding
capacity 135 has a configuration in which the first interlayer
insulating layer 11 is interposed between the gate electrode layer
21 and the relay electrode 43 as shown in FIG. 5.
[0077] The relay electrode 44 is connected to the drain region 140d
through a contact hole 35 which respectively opens the first
interlayer insulating layer 11 and the gate electrode layer 21.
[0078] A second interlayer insulating layer 12 is formed so as to
cover the relay electrodes 41, 42, 43, and 44 or the first
interlayer insulating layer 11. A conductive wiring layer is formed
on the front surface of the second interlayer insulating layer 12,
and relay electrodes 61 and 62, and the power supply line 116 are
respectively formed by patterning the wiring layer.
[0079] Among these, the relay electrode 61 is connected to the
relay electrode 41 through a contact hole 51 which opens the second
interlayer insulating layer 12. The relay electrode 62 is also
connected to the relay electrode 43 through a contact hole 52 which
opens the second interlayer insulating layer 12.
[0080] The power supply line 116 is connected to the relay
electrode 44 through a contact hole 53 which opens the second
interlayer insulating layer 12. For this reason, the power supply
line 116 is connected to the drain region 140d through the relay
electrode 44. The power supply line 116 is formed in the horizontal
direction where the scanning line 112 extends as shown in FIG. 4
when seen in the plan view.
[0081] In addition, the relay electrodes 41 and 61, the relay
electrodes 43 and 62, and the relay electrode 44 and the power
supply line 116 may be connected to the contact holes 51, 52, and
53 respectively, by filling up a columnar connection plug which is
formed of a high melting point metal such as tungsten.
[0082] A third interlayer insulating layer 13 is formed so as to
cover the relay electrodes 61 and 62, and second interlayer
insulating layer 12. A conductive wiring layer is formed on the
front surface of the third interlayer insulating layer 13, and the
data line 114, shield wires 81a and 81b (not shown in FIG. 5), and
a relay electrode 82 are respectively formed by patterning the
wiring layer.
[0083] Among these, the data line 114 is connected to the relay
electrode 61 through a contact hole 71 which opens the third
interlayer insulating layer 13. For this reason, the data line 114
is connected to a drain region 130d following paths of the relay
electrodes 61 and 41. Here, the data line 114 is formed in the
vertical direction which is orthogonal to the extension direction
of the scanning line 112 as shown in FIG. 4 when seen in the plan
view.
[0084] A relay electrode 82 is connected to the relay electrode 62
through a contact hole 72 which opens the third interlayer
insulating layer 13.
[0085] In addition, the relay electrode 61 and the data line 114,
and the relay electrodes 62 and 82 may be respectively connected to
the contact holes 71 and 72, by filling up a columnar connection
plug which is formed of a high melting point metal.
[0086] Each of the shield wires 81a and 81b is respectively formed
corresponding to each column as shown in FIG. 4 when seen in the
plan view.
[0087] In detail, a shield wire 81a on a certain column is formed
in the horizontal direction on the right side of a data line 114 so
as to be positioned between the data line 114 on the column and a
transistor 140 in a pixel circuit 110 on the column. At this time,
the shield wire 81a is provided to be close to the data line 114
when comparing between the data line 114 and the transistor 140.
That is, the distance between the shield wire 81a and the data line
114 is set to be shorter than the distance between the shield wire
81a and the transistor 140. For this reason, the shield wire 81a
easily perform the capacitative coupling with the data line 114
compared to the transistor 140.
[0088] On the other hand, a shield wire 81b on a certain column is
formed in the vertical direction on the left side of a data line
114 so as to be positioned between a neighboring data line 114 on
the right side with respect to the column and a transistor 140 in a
pixel circuit 110 on the column. At this time, the shield wire 81b
is provided to be close to the data line 114 when comparing between
the data line 114 and the transistor 140. That is, the distance
between the shield wire 81b and the data line 114 is shorter than
the distance between the shield wire 81b and the transistor 140.
For this reason, the shield wire 81b easily perform the
capacitative coupling with the data line 114 compared to the
transistor 140.
[0089] The shield wires 81a and 81b are disposed to be interposed
between a data line 114 on the left side and a data line 114 on the
right side, however, the shield wire 81a is disposed before the
data line 114 on the left side and the shield wire 81b is disposed
before the data line 114 on the right side, when seen from the
transistor 140 in the plan view.
[0090] In addition, the shield wires 81a and 81b are formed in the
vertical direction as shown in FIG. 4, and are extended to the
outside of a region where the pixel circuit 110 is arranged, and
are applied with a constant potential in time, for example, the
potential Vel is applied thereto.
[0091] Further, the shield wires 81a and 81b may be connected
through a contact hole in a portion which intersects with the power
supply line 116 when seen in the plan view for every one row, or
for a couple of rows.
[0092] A fourth interlayer insulating layer 14 is formed so as to
cover the data line 114, the shield wires 81a and 81b, and a relay
electrode 82, or the third interlayer insulating layer 13. A wiring
layer with conductivity and reflectivity is formed on the front
surface of the fourth interlayer insulating layer 14, and an anode
of the light emitting layer 150 is formed by patterning the wiring
layer. The anode is an individual pixel electrode for each pixel
circuit 110, and is connected to a relay electrode 82 through a
contact hole 92 which opens the fourth interlayer insulating layer
14. For this reason, the anode (pixel electrode) is connected to
the source region 140s following paths of the relay electrodes 82
and 62, and the relay electrode 43 which also functions as the
other electrode of the holding capacity 135.
[0093] In addition, the relay electrode 82 and the pixel circuit
may be connected to the contact hole 92, by filling up the
connecting plug of the columnar shape which is formed of a high
melting point metal.
[0094] Further structure of the electro-optical device 1 will not
be shown, however, a light-emitting layer which is formed of an
organic EL material is laminated to the anode for every pixel
circuit 110, and a common transparent electrode is provided in each
pixel circuit 110 as a common electrode 118 which functions as the
cathode, as well. In this manner, the light emitting element 150
becomes an OLED which interposes the light-emitting layer with the
anode and the cathode which face each other, emits light with a
brightness corresponding to a current which flows from the anode
toward the cathode, and is observed toward the direction opposite
to the substrate 2 (top emission structure). In addition to this,
sealing glass for cutting off the light-emitting layer from the
air, or the like, is provided, however, the description thereof
will be omitted.
[0095] In addition, in FIG. 4, since a pixel electrode as the anode
of the light emitting element 150 is not shown in the drawing, the
contact hole 92 only has the ".quadrature." mark applied which
denotes the position thereof.
[0096] Subsequently, a shielding function due to the shield wires
81a and 81b will be described with reference to FIG. 6. FIG. 6 is a
diagram which shows the pixel circuit 110 shown in FIG. 4 for which
the planar structure is replaced with an electrical circuit.
[0097] As described above, since the data line 114 of each column
is subject to potential fluctuation, noise which is caused by the
potential fluctuation propagates to each part of the pixel circuit
110.
[0098] According to the first embodiment, the shield wire 81a is
positioned before the gate node g and the source node of the
transistor 140 on the ith row and jth column when seen from the
data line 114 on the jth column. For this reason, the noise
generated from the data line 114 on the jth column is absorbed by
the capacitative coupling Ca between the shield wire 81a and the
data line 114 on the jth column.
[0099] In addition, the shield wire 81b is also positioned before
the gate node g and the source node of the transistor 140 on the
ith row and jth column when seen from the data line 114 on the
(j+1)th column. For this reason, the noise which is generated from
the data line 114 on the (j+1)th column is absorbed by the
capacitative coupling Cb between the shield wire 81b and the data
line 114 on the (j+1)th column.
[0100] Therefore, according to the electro-optical device 1, it is
possible to perform a stable display, since the gate node g and the
source node of the transistor 140 are not easily influenced by
noise which is caused by the potential fluctuation of the data line
114.
[0101] In addition, according to the first embodiment, since the
shield wires 81a and 81b are formed by patterning the same wiring
layer as that of the data line 114 or the relay electrode 82,
additional processes are not necessary in the manufacturing
process.
[0102] FIG. 7 is a diagram which shows an equivalent circuit of the
pixel circuit 110 along with the parasitic capacitance of each
unit.
[0103] In the drawing, C.sub.Dg denotes the parasitic capacitance
which is generated between the drain node D (data line 114) of the
transistor 130 and the gate node g of the transistor 140, and
C.sub.Ds denotes the parasitic capacitance which is generated
between the drain node D of the transistor 130 and the source node
of the transistor 140.
[0104] C.sub.HOLD denotes a capacity of the holding capacity
135.
[0105] C.sub.gd denotes the parasitic capacitance which is
generated between the gate node g and the drain node d of the
transistor 140 (power supply line 116), C.sub.ds denotes the
parasitic capacitance which is generated between the drain node d
and the source node of the transistor 140, and C.sub.OLED denotes
capacitive components of the light emitting element 150.
[0106] In the pixel circuit 110, the transistor 130 is turned off
when corresponding scanning line is in a non-selection period. In
addition, the power supply line 116 and the common electrode 118
have a constant potential.
[0107] For this reason, the pixel circuit 110 in the non-selection
period can be expressed as a simplified model as shown in FIG. 8.
In addition, in the figure, Vamp is potential amplitude of the data
line 114 in the non-selection period.
[0108] In this model, a fluctuation portion .DELTA.Vgs which is
given to the holding voltage Vgs of the holding capacity 135 can be
expressed as shown in the expression (1) in FIG. 8. In addition, a
coefficient K.sub.1 in the expression (1) is expressed as shown in
the expression (2), and a coefficient K.sub.2 is expressed as shown
in the expression (3).
[0109] Since the embodiment include the shield wires 81a and 81b,
the respective parasitic capacities C.sub.Dg and C.sub.Ds become
small compared to a configuration which does not include the shield
wires 81a and 81b.
[0110] For this reason, since the component of (a) in the
expression (2), and all components of denominator become large, the
coefficient K.sub.1 becomes small. On the other hand, since the
component of (b) in the expression (3), and all component of
denominator become large, the coefficient K.sub.2 becomes
small.
[0111] Accordingly, in the embodiment, since the fluctuation
portion .DELTA.Vgs with respect to the potential amplitude Vamp
becomes small compared to the configuration which does not include
the shield wires 81a and 81b, it is possible to perform a stable
display which is not easily influenced by the potential fluctuation
of the data line 114, the noise, or the like.
[0112] Here, when the potentials of the gate node g and the source
node are fluctuated due to the noise which is caused by the
potential fluctuation of the data line 114, in detail, when the
fluctuation is actualized as a crosstalk as follows, the display
quality is deteriorated.
[0113] FIGS. 9A and 9B are diagrams which show an example of the
crosstalk which is generated in an electro-optical device which
does not include the shield wires 81a and 81b of the
embodiment.
[0114] Here, as shown in FIG. 9A, crosstalk means a phenomenon in
which, for example, when a black rectangular region is displayed on
a window with a gray background region, in practice, as shown in
FIG. 9B, the upper region (a2) and the lower region (c2) are
displayed with different dark gray scale from the other gray
regions (a1, a3, b1, b3, c1, and c3) with respect to the black
region (b2).
[0115] In addition, in FIGS. 9A and 9B, brightness of the regions
is expressed by a density of an oblique line. Further, crosstalk is
also generated when the region (b2) is white. In both cases, since
the region which is expressed with different gray scale appears in
the up and down directions of the region (b2), it is sometimes
especially referred to as vertical crosstalk.
[0116] It is considered that the vertical crosstalk is generated
due to following reasons. That is, in a frame, a data line 114
which extends over the regions (a1, b1, and c1) has a constant
potential corresponding to gray scale data over the selection from
the first row to the last row m. For this reason, the pixel circuit
110 which belongs to the regions (a1, b1, and c1) holds the
potential which is held in the gate node g due to a selection of a
scanning line which corresponds to the own circuit, without being
influenced by noise from the data line, respectively. The same is
applied to a data line 114 which extends over regions (a3, b3, and
c3), and a pixel circuit 110 which belongs to the regions (a3, b3,
and c3). For this reason, each of pixel circuits 110 which belong
to the regions (a1, a3, b1, b3, e1, and c3) emit light with a
brightness which corresponds to the holing potential of the gate
node g, in the entire region of a time period corresponding to one
frame.
[0117] On the contrary, a data line 114 which extends over regions
(a2, b2, and c2) has a potential which corresponds to gray gray
scale data during selecting the region (a2), has a low potential
which corresponds to black gray scale data during selecting the
region (b2), and returns to the potential corresponding to the gray
scale data during selecting the region (c2).
[0118] For this reason, in the pixel circuit 110 which belongs to
the region (a2), even if the circuit holds a potential in which the
gate node g corresponds to gray, due to a selection of a scanning
line corresponding to the own circuit, the potential may change due
to the noise which is caused by the potential fluctuation of the
data line 114 when selecting the region (b2).
[0119] In addition, since the data line 114 returns to the
potential corresponding to the gray when selecting the region (c2),
the gate node g returns to the potential corresponding to the gray
due to the returning of the data line 114. Alternatively, there is
a possibility of approaching the potential.
[0120] However, for example, even if the gate node g returns to the
potential corresponding to the gray, each of the pixel circuits 110
which belongs to the region (a2) emits light with a brightness
corresponding to the potential which is lowered from the potential
corresponding to the gray, during selecting at least the region
(b2), in a period corresponding to one frame, after writing.
[0121] The same is applied to the region (c2). That is, in the
pixel circuit 110 which belongs to the region (c2), even if the
circuit holds the potential to which the gate node g corresponds to
the gray due to a selection of a scanning line corresponding to the
own circuit, the potential may change by being influenced by the
potential fluctuation of the data line 114 when selecting the
region (b2) in the next frame.
[0122] Accordingly, when considering the mean value of a period
corresponding to one frame, each of the pixel circuits 110 which
belongs to the regions (a2 and b2) is looked dark gray scale
differently from each of the pixel circuits 110 which belongs to
other regions (a1, a3, b1, b3, c1, and c3). It is considered that
this is the mechanism in which the vertical crosstalk is
generated.
[0123] According to the first embodiment of the invention, since
each of the gate node g and the source node have a structure which
is not easily influenced by noise which is caused by the potential
fluctuation of the data line 114, due to the shield wires 81a and
81b, it is possible to suppress such a vertical crosstalk, and
perform a display of high quality.
[0124] In addition, according to the first embodiment, the shield
wires 81a and 81b were set to the same potential Vel as that of the
power supply line 116, however, the shield wires may be held to
another potential, for example, to the potential Vet.
Second Embodiment
[0125] According to the first embodiment, the shield wires 81a and
81b were formed, by patterning the same wiring layer as that of the
data line 114, however, the shield wires may be formed of a wiring
layer different from that of the data line 114. Therefore,
subsequently, as a second embodiment, an example will be described,
in which the shield wires 81a and 81b are formed of the same wiring
layer as that of the relay electrodes 61 and 62 which are on the
lower side of the data line 114, and the power supply line 116.
[0126] FIG. 10 is a plan view which shows a configuration of a
pixel circuit 110 of an electro-optical device in the second
embodiment. FIG. 11 is a partial cross-sectional view of the pixel
circuit shown in FIG. 10 which is cut along line XI-XI.
[0127] When forming shield wires 81a and 81b from the same wiring
layer as that of relay electrodes 61 and 62, and a power supply
line 116, it is necessary to avoid interference (electrical
contact) from the shield wire 81a and the relay electrode 61. In
detail, it is necessary to provide a contact hole 51 to the outside
(to the left side in FIGS. 10 and 11) of the shield wires 81a when
seen in the plan view.
[0128] For this reason, in the second embodiment, as shown in FIG.
10, the contact holes 51 and 71 are arranged so as to be overlapped
with each other at the same location when seen in the plan view,
and a relay electrode 41 is extended to the same location. It is
needless to say that the contact holes 51 and 71 may be arranged at
a different location when seen in the plan view, for example, by
extending a relay electrode 61 to a different location, or the like
(now shown in the drawing).
[0129] Even in the second embodiment, since the shield wire 81a is
positioned before each node of a transistor 140 on the ith row and
jth column in the plan view, when seen from a data line 114 on the
jth column, noise which is generated from the data line 114 on the
jth column is absorbed by a capacitative coupling between the
shield wire 81a and the data line 114 on the jth column.
[0130] In addition, the shield wire 81b is also positioned before
each node of the transistor 140 on the ith row and jth column in
the plan view, when seen from the data line 114 on a (j+1)th
column, noise which is generated from the data line 114 on the
(j+1)th column is absorbed by a capacitative coupling between the
shield wire 81b and the data line 114 on the (j+1)th column.
[0131] For this reason, also in the second embodiment, it is
possible to perform a stable display, since it is not easily
influenced by noise or the like.
[0132] In addition, in the second embodiment, the shield wires 81a
and 81b are formed by patterning the same wiring layer as that of
the relay electrodes 61 and 62, and the power supply line 116, it
is not necessary to provide additional processes in the
manufacturing process, similarly to the first embodiment.
[0133] Further, in the second embodiment, the shield wires 81a and
81b are formed using a wiring layer which is different from that of
the data line 114. For this reason, since the shield wires 81a and
81b do not come into contact with the data line 114, it is possible
to make the pitch of the pixel circuit narrow. That is, according
to the first embodiment, since the shield wires 81a and 81b are
formed of the same wiring layer as that of the data line 114, it is
necessary to separate the shield wires 81a and 81b from the data
line 114, in order to secure the shielding function. On the
contrary, since it is not necessary in the second embodiment, even
if the shield wires 81a and 81b are overlapped with the data line
114 when seen in the plan view, since electrical insulating is
secured if the shield wires and the data line are separated at a
portion of the relay electrode 61, it is possible to make the pitch
narrow easily.
[0134] Meanwhile, if the shield wire is formed to intersect with
each node in the transistor 140 when seen in the plan view, more
powerful shielding function is expected. Therefore, an example in
which the shield wire is formed of the same wiring layer as that of
the data line, and the shielding function is strengthened will be
described as a third embodiment and a fifth embodiment. In
addition, an example in which the shield wire is formed of a wiring
layer different from that of data line, and the shielding function
is strengthened will be described later as a sixth embodiment and a
seventh embodiment.
Third Embodiment
[0135] FIG. 12 is a plan view which shows a configuration of a
pixel circuit 110 of an electro-optical device according to a third
embodiment. FIG. 13 is a partial cross-sectional view of the pixel
circuit in FIG. 12 which is cut along line XIII-XIII.
[0136] As shown in FIG. 12, in the third embodiment, a part of a
shield wire 81a is extended toward the right side, and is formed to
cover a relay electrode 43 when seen in the plan view. A holding
capacity 135 is a region where the relay electrode 43 and a gate
electrode layer 21 are overlapped with each other when seen in the
plan view. The relay electrode 43 is the other electrode in the
holding capacity 135, and also is a source node of the transistor
140. For this reason, in the third embodiment, the shielding
function is further strengthened compared to the first
embodiment.
Fourth Embodiment
[0137] FIG. 14 is a plan view which shows a configuration of a
pixel circuit 110 of an electro-optical device according to a
fourth embodiment.
[0138] As shown in FIG. 14, shield wires 81a and 81b are
respectively formed in a strip shape along a data line 114 for
every pixel circuit 110, and are respectively connected to a power
supply line 116. In addition, in the fourth embodiment, the shield
wires 81a and 81b are formed of the same wiring layer as that of
the data line 114. For this reason, the shield wire 81a is
connected to the power supply line 116 through a contact hole 73
which opens the third interlayer insulating layer 13. Similarly,
the shield wire 81b is connected to the power supply line 116
through a contact hole 74 which opens the third interlayer
insulating layer 13. In addition, a cross-sectional view thereof
will be omitted.
[0139] If the shield wires 81a and 81b are formed to be one line
along the data line 114, respectively, similarly to the first
embodiment, there may be a case where it is not possible to
sufficiently absorb the noise, since the impedances of the shield
wires 81a and 81b become relatively high, when resistivity thereof
is relatively high, or when the shield wires are separated from a
connection point of the constant potential. On the contrary,
according to the fourth embodiment, since the shield wires 81a and
81b are provided for every pixel circuit 110, and are connected to
the power supply line 116, it is possible to obtain low impedance,
and to increase the noise absorbing ability.
Fifth Embodiment
[0140] FIG. 15 is a plan view which shows a configuration of a
pixel circuit 110 of an electro-optical device according to a fifth
embodiment. The fifth embodiment is a combination of the third
embodiment and the fourth embodiment, and is formed to cover a
relay electrode 43 when seen in the plan view, by changing the
shape of the shield wire 81a shown in FIG. 14.
[0141] For this reason, according to the fifth embodiment, it is
possible to raise the noise absorbing ability, by strengthening a
shielding function.
Sixth Embodiment
[0142] Similarly to the second embodiment, when a shield wire is
formed of a wiring layer which is different from that of a data
line 114, it is preferable that the shield wire be provided at the
lower side of the data line 114 so as to be overlapped with the
data line 114 when seen in the plan view, not at both sides of the
data line 114.
[0143] On the other hand, it was already mentioned in the fourth
embodiment (fifth embodiment) that it is possible to raise the
noise absorbing ability, when the shield wire is connected, for
example, to a power supply line 116 for every pixel circuit
110.
[0144] Accordingly, subsequently, a sixth embodiment, as a
combination of both, will be described in which a shield wire is
formed of a wiring layer which is different from that of a data
line 114, is provided at the lower side of the data line 114 so as
to be overlapped with the data line 114 when seen in the plan view,
and is integrated with the power supply line 116.
[0145] FIG. 16 is a plan view which shows a configuration of a
pixel circuit 110 of an electro-optical device according to the
sixth embodiment, and FIG. 17 is a partial cross-sectional view of
the pixel circuit in FIG. 16 which is cut along line XVI-XVI.
[0146] The shield wires 81a and 81b are provided per column in the
first embodiment to fifth embodiment, however, in the sixth
embodiment, the shield wires 81a and 81b are integrated into one
shield wire 81, and also functions as the power supply line
116.
[0147] As shown in FIG. 17, the shield wire 81 which also functions
as the power supply line 116 is one in which a wiring layer formed
in the second interlayer insulating layer 12 is patterned, along
with the relay electrodes 61 and 62. As shown in FIG. 16, the shape
of the shield wire 81 when seen in the plan view is that it has a
wider width than the data line 114 so as to overlap with the
vertical data line 114, and has a lattice shape by being integrated
with the horizontal power supply line 116.
[0148] The data line 114 is connected to the drain region 130d
through the relay electrodes 61 and 41 in order, however, since the
shield wire 81 is formed of the same wiring layer as that of the
relay electrode 61, it is not necessary to avoid the interference.
For this reason, the data line 114 is branched to the right in FIG.
16, and is extended to a portion where the shield wire 81 is not
formed. The contact hole 51 is formed at the extended portion, and
connects the data line 114 to the relay electrode 61. In this
manner, it is possible to electrically separate the shield wire 81
and the relay electrode 61 from each other without being
interfered.
[0149] In addition, in this example, the contact holes 51 and 71
are arranged to be overlapped with each other at the same location
when seen in the plan view. However, the contact holes 51 and 71
may be arranged at different location (not shown in the
figure).
[0150] Meanwhile, in the sixth embodiment, since the data line 114
is branched and extended to the right, there is a possibility that
the noise may jump into the gate node g and the source node of the
transistor 140 from the extended portion. For this reason, in the
sixth embodiment, a branch wire 81d, which is the shield wire 81
extended to the right, is provided between a branch portion of the
data line 114 and the relay electrode 43 and gate electrode 21,
when seen in the plan view. In this manner, a portion which is
extended to the right side of the data line 114, that is, noise
from the vicinity of the contact hole 71 is absorbed by the branch
wire 81d, before reaching each node of the transistor 140.
[0151] According to the sixth embodiment, since the shield wire 81
is provided so as to be overlapped with the data line 114 when seen
in the plan view, and of which potential is fixed by functioning as
the power supply line 116 as well, it is possible to strengthen the
shielding function.
Seventh Embodiment
[0152] FIG. 18 is a plan view which shows a configuration of a
pixel circuit 110 of an electro-optical device according to a
seventh embodiment.
[0153] As shown in the figure, in the seventh embodiment, the
shield wire 81 which also functions as the power supply line 116 is
to cover the holding capacity 135 (gate electrode layer 21) and the
transistor 140 when seen in the plan view.
[0154] As described above, the shield wire 81 (power supply line
116) is formed by patterning the same wiring layer as that of the
relay electrodes 61 and 62, it is necessary to avoid the
interference with the relay electrodes 61 and 62. In the seventh
embodiment, the shield wire 81 which also functions as the power
supply line 116 has an open shape in the vicinity region of the
relay electrodes 61 and 62.
[0155] In addition, the cross-sectional view of the main part of
the pixel circuit 110 in the seventh embodiment will be a view to
which the portion which is denoted by the broken line in FIG. 17 is
added.
[0156] According to the seventh embodiment, the shield wire 81 is
provided to be overlapped with the data line 114 when seen in the
plan view, and to cover the holding capacity 135 and the transistor
140. In addition, since the potential thereof is fixed because it
functions as the power supply line 116 as well, the shielding
function thereof is further strengthened.
[0157] In addition, in the seventh embodiment, the open area of the
shield wire 81 may be further narrowed as long as it is not
interfering with the relay electrodes 61 and 62. Further, in the
seventh embodiment, the shield wire 81 is supposed to cover the
entire region of the holding capacity 135 and the transistor 140
when seen in the plan view, however, it may cover only a part
thereof.
Application/Modified Example
[0158] The invention is not limited to the above described
embodiments, and can be applied and modified.
[0159] For example, in a configuration of the holding capacity 135,
the first interlayer insulating layer 11 was interposed between the
gate electrode 21 and the relay electrode 43, however, for example,
the gate insulating layer 10 may be interposed between a
semiconductor layer and the gate electrode 21, by providing the
semiconductor layer to be overlapped with the gate electrode layer
21, when seen in the plan view. As the semiconductor layer, a layer
in which the source region 140s is extended may be used, or a layer
which is separately patterned may be used. In addition to these, a
configuration in which an interlayer insulating layer or a gate
insulating layer is interposed between an electrode and wiring
which are formed of different wiring layer may be adopted. In
addition, a plurality of layers which is connected in parallel may
be used as the overall holding capacity 135.
[0160] In addition, a position to which the holding capacity 135 is
electrically inserted may be a location, for example, between the
gate node g and the common electrode 118 as shown in FIG. 19, in
addition to a location between gate node g and the source node of
the transistor 140. It may be a location between the gate node g
and a wiring which is fixed to other potential, even though it is
not particularly shown in the figure.
[0161] The driving of the pixel circuit 110 is not limited to a
method in which a data signal of a potential which simply
corresponds to gray gray scale data is held in the gate node g, in
a selection period where the transistor 130 is on state. For
example, the driving of the pixel circuit may be performed such
that the data line 114 is set to a reference potential in the
selection period in which the transistor 130 is turned on, a power
source due to the power supply line 116 and the common electrode
118 is switched between a first potential and a second potential, a
voltage corresponding to a threshold voltage of the transistor 140
is held in the holding capacity 135, and after that the data line
114 becomes a potential which corresponds to the gray gray scale
data. In addition, the driving of the pixel circuit may be
performed such that the potential of the data signal is changed in
the selection period, and time rate of change of the data signal at
the end of selection period is set to a value which corresponds to
the gray gray scale data. Further, the driving of the pixel circuit
may be performed such that a lamp signal is provided to the source
node through a capacitive element for every row, and causes a set
current to flow to the transistor 140.
[0162] In any driving, it is possible to suppress the fluctuation
of the potential of each node of the transistor 140 which flows a
current to the light emitting element 150, by providing a shield
wire of each embodiment in the pixel circuit 110 due to the noise
from the data line 114.
[0163] In the shield wire, it is preferable to adopt a wiring layer
in which two or more different wiring layers are patterned. For
example, in the sixth (seventh) embodiment, it is preferable to
have a double structure of the shield wire 81 (power supply line
116) and a separately formed shield wire, by patterning the data
line 114 and the same wiring layer as that of the relay electrode
82. In addition, in the separate shield wire, it is preferable to
avoid the interference with the data line 114 and the relay
electrode 82.
[0164] As the light emitting element 150, an element which emits
light with a brightness corresponding to a current, such as an
inorganic EL element, an LED (Light Emitting Diode), or the like
may be adopted, in addition to the OLED.
Electronic Apparatus
[0165] Subsequently, an electronic apparatus to which an
electro-optical device according to the embodiment of the invention
is applied will be described.
[0166] FIG. 20 is a diagram which shows the appearance of a
personal computer to which the electro-optical device 1 according
to the above described embodiment is adopted as a display device.
The personal computer 2000 includes the electro-optical device 1
and a main body unit 2010 as a display device. The main body unit
2010 is provided with a power supply switch 2001 and a key board
2002.
[0167] When an OLED is used in a light emitting element 150, in the
electro-optical device 1, it is possible to display a screen of
which viewing angle is wide, and which is easy to view.
[0168] FIG. 21 is a diagram which shows the appearance of a mobile
phone to which the electro-optical device 1 according to the above
described embodiment is adopted as a display device. The mobile
phone 3000 includes an ear piece 3003, a mouth piece 3004, and the
above described electro-optical device 1, in addition to a
plurality of operation buttons 3001, an arrow key 3002, or the
like. By operating the arrow key 3002, the screen displayed in the
electro-optical device 1 is scrolled.
[0169] FIG. 22 is a diagram which shows the appearance of a PDA
(Personal Digital Assistant) to which the electro-optical device 1
is adopted as the display device according to the embodiment of the
invention. The PDA 4000 includes the above described
electro-optical device 1, in addition to a plurality of operation
buttons 4001, an arrow key 4002, or the like. In the PDA 400, a
variety of information such as an address book, a diary, or the
like, is displayed in the electro-optical device 1 by a
predetermined operation, and the displayed information is scrolled
according to the operation of the arrow key 4002.
[0170] In addition, as electronic apparatuses to which the
electro-optical device according to the embodiment of the invention
is adopted, for example, there are a television, a car navigation
system, a pager, an electronic organizer, electronic paper, a
calculator, a word-processor, a work station, a TV phone, a POS
terminal, a printer, a scanner, a copy machine, a video player,
equipment with a touch panel, or the like, in addition to the
equipments exemplified in FIGS. 20 to 22. Particularly, as a
micro-display, for example, there are a head-mounted display, a
digital still camera, an electronic view finder of a video camera,
or the like.
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