Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
1999-11-12
2003-04-01
Vu, David Hung (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C313S506000, C345S080000
Reexamination Certificate
active
06541918
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an active-matrix light-emitting apparatus. In particular, the present invention relates to an active-matrix display apparatus that performs driving-control of electronic devices, such as EL (electroluminescent) devices and LED (light-emitting diode) devices, that are caused to emit light by a driving current flowing to emitting layers such as organic semiconductor films using thin-film transistors (hereinafter, referred to as TFTs), and relates to a fabrication method therefor.
2. Description of Related Art
Active-matrix light-emitting apparatuses, particularly, the apparatuses used for active-matrix type display apparatuses using current-control light-emitting devices, such as EL devices and LED devices, have been proposed. The light-emitting devices used in display apparatuses of this type emit light by themselves. Therefore, unlike liquid crystal display apparatuses, they have advantages in such aspects in that they do not require a backlight and that they are less dependent on viewing angles.
FIG. 1
is a schematic view of a circuit configuration in an active-matrix display apparatus using organic thin-film EL devices of a charge-injection type as current-control light-emitting devices. In the active-matrix display apparatus
1
shown in this figure, switching circuits
50
and light-emitting devices
40
are individually formed for pixels
7
, in which the pixels
7
are formed in a matrix by a plurality of scanning lines “gate” and a plurality of data lines “sig”, switching circuits
50
are fed with scanning signals through the scanning lines “gate”, and the light-emitting devices
40
emit light in response to image signals fed from data lines “sig” through the switching circuits
50
. In the illustrated example, each of the switching circuits
50
is formed of a first TFT
20
in which scanning signals are fed to its gate electrode through the scanning line “gate”, a capacitor “cap” for storing image signals fed from the data line “sig” through the first TFT
20
, and a second TFT
30
in which the image signals stored in the capacitor “cap” are fed to its gate electrode. When the second TFT
30
is turned on, a driving current flows from a common feeder line “com” into the light-emitting device
40
to cause the device to emit light, and the light-emitting state is maintained according to the capacitor “cap”.
FIGS. 2 and 3
are plan views of a portion of the pixels shown in FIG.
1
. In
FIG. 2
, conductive films forming elements such as the scanning lines “gate” and capacitor lines “cs” are indicated by lines slanting up to the right; elements such as conductive films forming the data lines “sig” and the common feed lines “com” are indicated by lines slanting down to the right. In
FIG. 3
, regions in which the light-emitting layers
43
composing the light-emitting devices
40
are formed are indicated by lines slanting down to the right. For reference, in the illustrated example, an insulation film “in” defining the regions in which light-emitting layers
43
are formed is arranged in a border region in which the data line “sig” and the common feed line “com” extend in a border region between the individual pixels
7
, therefore, the regions in which the insulation films “in” are formed are indicated by the lines slanting up to the right. In addition, in
FIGS. 2 and 3
, regions in which semiconductor films forming the first TFTs
20
and the TFTs
30
are formed are indicated by bold lines; regions in which pixel electrodes
41
are formed are indicated by bold dotted lines. In addition, respective cross sections along the lines A-A′, B-B′, and C-C′ in
FIGS. 2 and 3
are shown in
FIGS. 12
,
13
, and
14
.
In these figures, the first TFT
20
has a structure in which a gate electrode is formed as a part of the scanning line “gate”, and the data line “sig” and a storage electrode
22
are respectively formed in a source region and a drain region through a contact hole of an interlayer insulation film
51
. The storage electrode
22
extends toward the region in which the second TFT
30
is formed, and a gate electrode
31
of the second TFT
30
is electrically connected through the contact hole in the interlayer insulation film
51
in the foregoing extension portion. The capacitor line “cs” is formed at a side portion of the scanning line “gate”, and the capacitor line “cs” is commonly positioned for the drain region of the first TFT
20
and the storage electrode
22
via the first interlayer insulation film
51
and a gate insulation film
55
to form the capacitor “cap”. A junction electrode
35
is electrically connected to either one of the drain region and the source region of the first TFT
30
through the contact hole in the first interlayer insulation film
51
, and a pixel electrode
41
is electrically connected to the junction electrode
35
through a contact hole in a second interlayer insulation film
52
. To the other of the drain region and the source region, the common feeder line “com” is electrically connected through the contact hole in the first interlayer insulation film
51
.
The pixel electrode
41
is formed independently for each pixel
7
. On an upper side of this pixel electrode
41
, a light-emitting layer
43
composing the light-emitting devices
40
and an opposing electrode “op” are overlaid in this order.
In the illustrated example, the insulation film “in” is formed in a region in which the data line “sig” and the common feeder line “com” extend, and the insulation film “in” insulates the light-emitting layers
43
of the light-emitting devices
40
of two pixels
7
which are arranged on both sides of the data line “sig” and the common feeder line “com”. However, the insulation film “in” is not formed between the pixels
7
arranged along the data line “sig” and the common feeder line “com”. In this direction, the light-emitting layers
43
of the light-emitting device
40
are formed in stripes so as to overlap a plurality of the pixels
7
. In this arrangement also, the first TFTs
20
of the individual pixels
7
turn on/off with a predetermined timing in response to scanning signals fed from the scanning lines “gate”, therefore, predetermined image signals are written to the individual pixels
7
from the data lines “sig”, and a current flows to the light-emitting layers formed in the border lines between the pixels.
In conventional active-matrix display apparatuses, although predetermined image signals from the data lines “sig” can be written to the individual pixels
7
, since the light-emitting devices
40
(light-emitting layers
43
) have electrical conductivity, a current also flows to between pixels (the border regions between the pixels) arranged along the data lines “sig” and the common feeder lines “com”, increasing the probability of occurrence of the so-called crosstalk. In addition, if charge injection layers such as hole injection layers, electron injection layers, and the like are formed in the light-emitting devices
40
in addition to the light-emitting layers for improving the light-emitting characteristics, the resistance of the charge injection layer is smaller than that of the light-emitting layer, and the difference in the resistance might further increase the probability of occurrence of crosstalk between the pixels arranged along the data lines “sig” and the common feeder line “com”.
SUMMARY OF THE INVENTION
In view of the above problems, objects of the present invention are to provide an active-matrix light-emitting apparatus and a fabrication method therefor, the active-matrix light-emitting apparatus being such that it has a plurality of pixels and is arranged so as to avoid crosstalk in the vicinity between the pixels, and to provide display of improved quality.
To solve the above problems, the present invention provides an active-matrix display apparatus that has pixel electrodes formed in individual pixels in a matrix by a plurality of scanning lines and a plurality of data lines, light-
Oliff & Berridg,e PLC
Seiko Epson Corporation
Vu David Hung
LandOfFree
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