(12) United States Patent
`Komiya et al.
`
`I 1111111111111111 11111 111111111111111 IIIII IIIII IIIII IIIII IIIIII IIII IIII IIII
`US006724149B2
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 6,724,149 B2
`*Apr. 20, 2004
`
`(54) EMISSIVE DISPIAY DEVICE AND
`ELECTROLUMINESCENCE DISPIAY
`DEVICE WITH UNIFORM LUMINANCE
`
`(75)
`
`Inventors: Naoaki Komiya, Ohgaki (JP); Ryoichi
`Yokoyama, Ohgaki (JP); Tsutomu
`Yamada, Gifu (JP); Ryuji Nishikawa,
`Gifu (JP)
`
`(73) Assignee: Sanyo Electric Co., Ltd., Osaka (JP)
`
`( *) Notice:
`
`This patent issued on a continued pros(cid:173)
`ecution application filed under 37 CFR
`1.53( d), and is subject to the twenty year
`patent term provisions of 35 U.S.C.
`154(a)(2).
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by O days.
`
`(21) Appl. No.: 09/510,853
`
`(22) Filed:
`
`Feb.23,2000
`
`(65)
`
`Prior Publication Data
`
`4,459,514 A * 7/1984 Morimoto et al. ....... 315/169.1
`4,704,559 A * 11/1987 Suginoya et al. ........ 315/169.1
`5,670,792 A * 9/1997 Utsugi et al. ................. 257/59
`5,684,365 A * 11/1997 Tang et al.
`.............. 315/169.3
`5,966,189 A * 10/1999 Matsuo ........................ 349/38
`
`OTHER PUBLICATIONS
`
`Japanese Notice of Ground for Rejection for Patent Appli(cid:173)
`cation Ser. No. HEI 11-046741, dated Aug. 27, 2002 with
`English Translation.
`
`Patent Abstracts of Japan, Publication No. 09-081053, dated
`Mar. 28, 1997.
`
`Japanese Patent Laid Open Publication No. HEI 10-239699,
`dated Sep. 11, 1998 with English Abstract and Partial
`English Translation.
`
`* cited by examiner
`
`Primary Examiner-Don Wong
`Assistant Examiner-Trinh Vo Dinh
`(74) Attorney, Agent, or Firm-Cantor Colburn LLP
`
`US 2003/0076046 Al Apr. 24, 2003
`
`(57)
`
`ABSTRACT
`
`(30)
`
`Foreign Application Priority Data
`
`Feb. 24, 1999
`Sep. 29, 1999
`
`(JP) ........................................... 11-046741
`(JP) ........................................... 11-277084
`
`Int. Cl.7 .................................................. G09G 3/10
`(51)
`(52) U.S. Cl. ..................................... 315/169.3; 313/505
`(58) Field of Search ........................... 315/169.3, 169.2,
`315/169.1; 313/500, 503, 504, 505, 506,
`463, 497; 345/76, 92, 77; G09G 3/10
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`3,869,646 A * 3/1975 Kirton et al.
`
`............... 315/246
`
`Power source lines (183) for supplying drive current from
`power source input terminals (180) to organic EL elements
`(160) formed in a display pixel region having display pixels
`are connected by a bypass line (181) along the row direction
`within the display pixel region. This arrangement minimizes
`decrease in power source current caused by resistance of the
`power source lines (183) according to the line length.
`Accordingly, the organic EL elements (160) can adequately
`receive the actual desired current, thereby achieving an
`organic EL device capable of bright displays and having
`uniform display luminance within the display region.
`
`9 Claims, 7 Drawing Sheets
`
`161
`
`165
`
`162
`
`167
`
`117
`183
`
`141
`112
`
`110
`
`151
`
`181
`
`141c 142
`
`141s
`
`141d
`
`LG Display Co., Ltd.
`Exhibit 1014
`Page 001
`
`

`

`U.S. Patent
`
`Apr. 20, 2004
`
`Sheet 1 of 7
`
`US 6,724,149 B2
`
`153
`
`:
`. -
`
`.
`.
`:'
`' . . . . . .
`
`G
`
`154
`
`------------------ ---------------·
`'
`
`'
`
`140
`
`R
`
`160
`
`Fig. 1 RELATED ART
`
`LG Display Co., Ltd.
`Exhibit 1014
`Page 002
`
`

`

`U.S. Patent
`
`Apr. 20, 2004
`
`Sheet 2 of 7
`
`US 6,724,149 B2
`
`D
`
`180
`
`D
`
`D
`
`--------- ------------ -
`
`------ - ---
`
`--- --- ------ -----------. ---
`DISPLAY
`G---+--------+--+--~'?'-----+---+-- PIXEL REGION
`
`--
`
`--
`
`Fig. 2 RELATED ART
`
`LG Display Co., Ltd.
`Exhibit 1014
`Page 003
`
`

`

`U.S. Patent
`
`Apr. 20, 2004
`
`Sheet 3 of 7
`
`US 6,724,149 B2
`
`131LD
`131LD
`131LD
`114 114
`
`116
`
`155
`
`131
`
`131c
`
`117
`115
`131
`112
`110
`
`132 132
`
`154
`
`1315
`131c
`Fig. 3A RELATED ART
`
`167
`166{1---------"I
`161
`,
`117
`
`,✓,,...,.......-,.....,.....,..........,....,.....,..
`
`115
`
`112
`
`110
`
`141
`
`141s 141c 142 142 141c
`
`141d
`
`Fig. 38 RELATED ART
`
`LG Display Co., Ltd.
`Exhibit 1014
`Page 004
`
`

`

`U.S. Patent
`
`Apr. 20, 2004
`
`Sheet 4 of 7
`
`US 6,724,149 B2
`
`183
`
`152
`
`182
`
`181
`
`183
`182
`
`.
`
`:
`
`. . . . . . . .
`
`--B
`
`140
`
`I R
`I
`
`' ' '-190
`
`I
`
`B
`
`Fig. 4
`
`LG Display Co., Ltd.
`Exhibit 1014
`Page 005
`
`

`

`U.S. Patent
`
`Apr. 20, 2004
`
`Sheet 5 of 7
`
`US 6,724,149 B2
`
`D
`
`180
`
`D
`
`D
`
`----------------------- ------ -----------. ---
`183
`DISPLAY
`G---+----e-----+---t--e---:,,'----t---+--p1xEL REGION
`
`Fig. 5
`
`LG Display Co., Ltd.
`Exhibit 1014
`Page 006
`
`

`

`U.S. Patent
`
`Apr. 20, 2004
`
`Sheet 6 of 7
`
`US 6,724,149 B2
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`LG Display Co., Ltd.
`Exhibit 1014
`Page 007
`
`

`

`U.S. Patent
`
`Apr. 20, 2004
`
`Sheet 7 of 7
`
`US 6,724,149 B2
`
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`LG Display Co., Ltd.
`Exhibit 1014
`Page 008
`
`

`

`US 6,724,149 B2
`
`1
`EMISSIVE DISPLAY DEVICE AND
`ELECTROLUMINESCENCE DISPLAY
`DEVICE WITH UNIFORM LUMINANCE
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`The present invention relates to an em1ss1ve display
`device using emissive elements, such as electrolumines- 10
`cence elements, which employs thin film transistors for
`controlling such elements.
`2. Description of the Related Art
`In recent years, electroluminescence (referred to herein(cid:173)
`after as "EL") display devices comprising EL elements have
`gained attention as potential replacements for CRTs and
`LCDS. Research has been directed to the development of EL
`display devices using, for example, thin film transistors
`(referred to hereinafter as "TFT") as switching elements to
`drive the EL elements.
`FIG. 1 is a plan view showing one display pixel of an
`organic EL display device. FIG. 2 illustrates an equivalent
`circuit for a plurality of display pixels in an organic EL
`display device. FIG. 3A shows a cross-sectional view taken
`along line A-A of FIG. 1, while FIG. 3B shows a cross(cid:173)
`sectional view taken along line B-B of FIG. 1.
`As shown in FIGS. 1, 2, 3A, and 3B, each display pixel
`is formed in a region surrounded by gate signal lines 151 and
`drain signal lines 152. A first TFT serving as a switching
`element is disposed near a intersection of those signal lines.
`The source 131s of the TFT simultaneously functions as a
`capacitor electrode 155 such that, together with the opposing
`storage capacitor electrode 154 described later, it forms a
`capacitor. The source 131s is connected to a gate electrode
`142 of a second TFT 140 that drives the organic EL element.
`The source 141s of the second TFT 140 contacts with the
`anode 161 of the organic EL element. The drain 141d is
`connected to a power source line 153.
`Near the TFT 130, a storage capacitor electrode 154 is
`disposed in parallel with a gate signal line 151. The storage
`capacitor electrode 154 is made of a material such as
`chromium. The storage capacitor electrode 154 contacts the
`capacitor electrode 155 via a gate insulating film 112 and
`together stores charges, forming a capacitor. The capacitor
`electrode 155 is connected to the source 131s of the first TFT
`130. This storage capacitor is provided for retaining voltage
`applied to the gate 142 of the second TFT 140.
`The first TFT 130, or the switching TFT, will now be
`explained.
`As shown in FIGS. 1 and 3A, gate signal lines 151 made
`of refractory metal such as chromium (Cr) or molybdenum
`(Mo), which also serve as gate electrodes 132, are formed on
`an insulator substrate 110 made of quartz glass, non-alkali
`glass, or a similar material. Also disposed on the substrate 55
`110 are drain signal lines 152 composed of aluminum (Al)
`and power source lines 153 also composed of Al and serving
`as the power source for the organic EL elements.
`After forming gate signal lines 151 on the substrate 110,
`a gate insulating film 112 and an active layer 131 composed
`of poly-silicon (referred to hereinafter as "p-Si") film are
`sequentially formed. The active layer 131 is of a so-called
`LDD (Lightly Doped Drain) structure. Specifically, low(cid:173)
`concentration regions 131LD are formed on both sides of
`each gate 132. The source 131s and the drain 131d, which
`are high-concentration regions, are further disposed on the
`outboard sides of the low-concentration regions 131LD.
`
`2
`An interlayer insulating film 115 formed by sequential
`lamination of a SiO2 film, a SiN film, and a SiO2 film is
`provided on the entire surface over the gate insulating film
`112, the active layer 131, and stopper insulating films 114.
`5 A contact hole formed in a position corresponding to the
`drain 141d is filled with metal such as Al, forming a drain
`electrode 116. Further, a planarizing insulating film 117
`made of an organic resin or a similar material is formed over
`the entire surface for planarization.
`The second TFT 140, or the TFT for driving the organic
`EL element, will next be described.
`As shown in FIG. 3B, gate electrodes 142 composed of
`refractory metal such as Cr or Mo are formed on the
`insulator substrate 110 made of quartz glass, non-alkali
`15 glass, or a similar material. Further on top, a gate insulating
`film 112 and an active layer 141 composed of p-Si film are
`sequentially formed. The active layer 141 is provided with
`intrinsic or substantially intrinsic channels 141c formed
`above the gate electrodes 142, and the source 141s and drain
`20 141d are formed on respective sides of these channels 141c
`by ion doping using p-type impurities, thereby constituting
`a p-type channel TFT.
`An interlayer insulating film 115 formed by sequential
`lamination of a SiO2 film, a SiN film, and a SiO2 film is
`25 provided on the entire surface over the gate insulating film
`112 and the active layer 141. A contact hole formed in a
`position corresponding to the drain 141d is filled with metal
`such as Al, forming a power source line 153 connected to a
`power source. Further, a planarizing insulating film 117
`30 made of an organic resin or a similar material is formed over
`the entire surface for planarization. A contact hole is formed
`in the planarizing insulating film 117 in a position corre(cid:173)
`sponding to the source 141s. A transparent electrode made of
`ITO (indium tin oxide) that contacts the source 141s through
`35 this contact hole, namely, the anode 161 of the organic EL
`element, is formed on the planarizing insulating film 117.
`The organic EL element 160 is formed by laminating, in
`order, the anode 161 constituted by a transparent electrode
`40 made of ITO or similar material, an emissive element layer
`166 which is composed with materials including an organic
`compound and comprises an emissive layer, and a cathode
`167 made of a magnesium-indium alloy. The cathode 167 is
`disposed over the entire surface of the organic EL display
`45 element shown in FIG. 1, that is covering the entire sheet of
`the figure.
`In an organic EL element, holes injected from the anode
`and electrons injected from the cathode recombine in the
`emissive layer. As a result, organic molecules constituting
`50 the emissive layer are excited, generating excitons. Through
`the process in which these excitons undergo radiation until
`deactivation, light is emitted from the emissive layer. This
`light radiates outward through the transparent anode via the
`transparent insulator substrate, resulting in light emission.
`In this way, electric charge applied via the source 131s of
`the first TFT 130 is accumulated in the storage capacitor 170
`and applied to the gate 142 of the second TFT 140. Accord(cid:173)
`ing to this voltage, the organic EL element emits light.
`As shown in FIG. 2, each power source line connected to
`60 the power source for driving the organic EL elements is
`connected with a power source input terminal 180 disposed
`outside the display pixel region. The power source lines are
`arranged and connected with each vertical array of display
`pixels. With such an arrangement, at positions more distant
`65 from the power source input terminal 180 resistance of each
`power source line increases along with its length. The
`organic EL elements 160 located in display pixels distant
`
`LG Display Co., Ltd.
`Exhibit 1014
`Page 009
`
`

`

`US 6,724,149 B2
`
`3
`from the power source input terminal 180 are therefore not
`adequately provided with necessary current, causing a dis(cid:173)
`advantage that the display in such area is dim.
`
`SUMMARY OF THE INVENTION
`
`The present invention was created in light of the above
`existing disadvantage. The purpose of the present invention
`is to provide an EL display device which prevents decrease
`in power source current due to resistance of power source
`lines, and adequately provides EL elements with current that
`should actually be supplied, accomplishing bright display.
`To achieve the above purpose, the present invention
`provides an electroluminescence display device comprising
`a plurality of display pixels arranged in a matrix within a
`display pixel region, said display pixels having electrolumi(cid:173)
`nescence elements including an emissive layer between first
`and second electrodes, wherein, within said display pixel
`region, power source line for supplying power from a power
`source to said electroluminescence elements is disposed in a
`grid pattern.
`According to another aspect of the present invention, said
`power source line includes main power source lines
`arranged in plural numbers within said display pixel region,
`and at least one bypass power source line extended to
`intersect and connect said main power lines within said
`display pixel region.
`In a further aspect of the present invention, each of said
`display pixels further comprises a first thin film transistor
`having a gate electrode connected to a gate line, and a first
`electrode region connected to a data line; and a second thin
`film transistor having a gate electrode connected to a second
`electrode region of said first thin film transistor, a first
`electrode region connected to one of said main power source
`lines, and a second electrode region connected to said
`electroluminescence element.
`In a still further aspect of the present invention, an
`emissive display device comprises a plurality of display
`pixels arranged in a matrix within a display pixel region,
`each of said display pixels having emissive elements includ(cid:173)
`ing an emissive layer between first and second electrodes;
`wherein, within said display pixel region, power source line
`for supplying power from a power source to said emissive
`elements is disposed in a grid pattern.
`According to another aspect of the present invention, in
`any one of the above-described devices, said power source
`line includes main power source lines arranged in plural
`numbers along the column direction of said matrix within
`said display pixel region, and at least one bypass power
`source line extended in the row direction of said matrix to 50
`intersect and connect a plurality of said main power lines.
`According to a further aspect of the present invention, in
`any one of the above-described devices, each of said display
`pixels further comprises a first thin film transistor having a
`gate electrode connected to a gate line, and a first electrode 55
`region connected to a data line; and a second thin film
`transistor having a gate electrode connected to a second
`electrode region of said first thin film transistor, a first
`electrode region connected to one of said main power source
`lines, and a second electrode region connected to said 60
`electroluminescence element or said emissive element.
`In another aspect of the present invention, there is pro(cid:173)
`vided an electroluminescence display device comprising a
`display pixel region having a plurality of display pixels
`arranged in a matrix. Each of said display pixels includes an 65
`electroluminescence element having an emissive layer
`between an anode and a cathode; a first thin film transistor
`
`10
`
`30
`
`4
`having a gate electrode connected to a gate line, and a first
`electrode region connected to a data line; and a second thin
`film transistor having a gate electrode connected to a second
`electrode region of said first thin film transistor, a first
`5 electrode region connected to a power source line for
`supplying power from a power source to said electrolumi(cid:173)
`nescence element, and a second electrode region connected
`to said electroluminescence element. Said power source line
`is provided in plural numbers along the column direction of
`said matrix within said display pixel region, and those power
`source lines that are associated with the display pixels
`adjacently arranged along the row direction are connected to
`one another via a bypass power source line extending in the
`row direction of said matrix.
`As described above, the power source line for supplying
`15 power ( current or voltage) from the power source to emis(cid:173)
`sive elements such as electroluminescence elements is
`arranged in a grid pattern. Alternatively, a plurality of main
`power source lines may be electrically connected by bypass
`power source line(s) arranged to intersect the main power
`20 source lines. Such an arrangement can minimize the differ(cid:173)
`ence between power supplied to emissive elements located
`near and far from the power source that arises from wiring
`resistance of the power source lines. Accordingly, the power
`that should be supplied can adequately be provided to each
`25 display pixel emissive element. Irregularities in the lumi(cid:173)
`nance between the display pixels that emit light according to
`supplied power can thereby be reduced, accomplishing
`uniform light emission within the display pixel region.
`According to a still further aspect of the present invention,
`in any one of the above-described devices, said first and said
`second thin film transistors include active layers composed
`of poly-silicon.
`Use of thin film transistors, especially those employing
`35 poly-silicon as the active layers, as elements for controlling
`the emissive elements can contribute to large display size
`and high resolution in display devices because thin film
`transistors are capable of high-speed operation and control
`emissive elements to reliably emit light during an appropri-
`40 ate period of time. Further, pixel driver circuits comprising
`poly-silicon thin film transistors created using similar pro(cid:173)
`cesses as the TFTs within the pixel region can be integrated
`on the same substrate where the display pixel region is
`formed. This can contribute to reducing the size of margins
`45 in a display device and to reduction in manufacturing cost of
`the overall display device.
`In another aspect of the present invention, said emissive
`layer may be a layer using an organic compound as an
`emissive material. Forming the emissive layer using an
`organic compound can be extremely advantageous espe(cid:173)
`cially in a color display device because organic compounds
`can provide many variations in emitted colors and a wide
`selection of materials.
`According to another aspect of the present invention, said
`main power source lines and said bypass power source line
`are conductive line integrally formed. Alternatively, said
`main power source lines and said bypass power source line
`may be conductive lines separately formed in different
`processes.
`In a further aspect of the present invention, said bypass
`power source line in the above-described device is formed in
`a layer located underneath said main power source lines and
`separated by an insulating layer, and is connected to said
`main power source lines via contact holes.
`In a still further aspect of the present invention, said
`bypass power source line is formed in a same layer as a gate
`line.
`
`LG Display Co., Ltd.
`Exhibit 1014
`Page 010
`
`

`

`US 6,724,149 B2
`
`5
`According to a further aspect of the present invention,
`said bypass power source line is formed on a gate insulating
`film, and an interlayer insulating film that separates the
`active layer of said second thin film transistor and a main
`power source lines is provided between said bypass power 5
`source line and said main power source line as said insu(cid:173)
`lating layer.
`These arrangements allow efficient and reliable formation
`of the main power source lines and the bypass power line.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a plan view illustrating a related art EL display
`device.
`FIG. 2 is a diagram showing an equivalent circuit for
`display pixels of the related art EL display device.
`FIG. 3A shows a cross-sectional view taken along line
`A-AofFIG.1.
`FIG. 3B shows a cross-sectional view taken along line
`B-B of FIG. 1.
`FIG. 4 shows a plan view of an EL display device
`according to an embodiment of the present invention.
`FIG. 5 is a diagram showing an equivalent circuit for
`display pixels of the EL display device according to the
`embodiment of the present invention.
`FIG. 6A show a cross-sectional view of the EL display
`device along line B-B of FIG. 4.
`FIG. 6B shows another cross-sectional view of the EL
`display device along line B-B of FIG. 4.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`
`6
`a gate electrode 142 of the second TFT 140. The source 141s
`of the second TFT 140 contacts with the anode 161 of the
`organic EL element 160. The drain 141d is connected to a
`power source line 183 for driving the organic EL element.
`Near the TFT 130, a first storage capacitor electrode 154
`is disposed in parallel with a gate signal line 151. The first
`storage capacitor electrode 154 is made of a material such as
`chromium, and a predetermined common voltage is applied
`to each of the storage capacitor electrode 154 as shown in
`10 FIG. 5. The storage capacitor electrode 154 is opposed to the
`capacitor electrode 155 via a gate insulating film 112 and
`together stores charges, forming a storage capacitor.
`In the first TFT 130 provided as the switching TFT, as
`shown in FIGS. 4 and 3A, gate signal lines 151 made of
`refractory metal such as Cr or Mo which also serve as gate
`15 electrodes 132 are formed on an insulator substrate 110
`made of quartz glass, non-alkali glass, or a similar material.
`Also disposed on the substrate 110 are drain signal lines 152
`composed of Al and power source lines 183 also composed
`of Al and serving as the power source for the organic EL
`20 elements. The first storage capacitor electrode 154 made of
`refractory metal such as Cr or Mo are provided in the same
`layer as the gate electrodes.
`After forming the gate signal lines 151 (gate electrodes
`132) and first storage capacitor electrodes 154, a gate
`25 insulating film 112 and an active layer 131 composed of p-Si
`film are sequentially formed. Stopper insulating films 114
`made of SiO2 are provided on top of the active layer 131
`above the gate electrodes 132. The stopper insulating films
`114 serve as masks that cover channels 131c for preventing
`30 ions from entering into the channels 131c during ion doping
`performed for forming the source 131s and the drain 131d.
`The active layer 131 is provided with the so-called LDD
`structure. Specifically, low-concentration regions 131LD are
`formed on both sides of each gate 132. The source 131s and
`35 the drain 131d, which are high-concentration regions, are
`further disposed on the outboard sides of the low(cid:173)
`concentration regions 131LD. The p-Si film of the active
`layer extends over the storage capacitor electrode 154 to
`function as the second storage capacitor electrode 155 which
`40 forms a storage capacitor together with the storage capacitor
`electrode 154 via the gate insulating film 112.
`An interlayer insulating film 115 formed by sequential
`lamination of a SiO2 film, a SiN film, and a SiO2 film is
`provided on the entire surface over the gate insulating film
`112, the active layer 131, and stopper insulating films 114.
`A contact hole formed in a position corresponding to the
`drain 141d is filled with metal such as Al, forming a drain
`electrode 116. Further, a planarizing insulating film 117
`made of an organic resin or a similar material is formed over
`the entire surface for planarization.
`The second TFT 140, or the TFT for driving the organic
`EL element 160, will next be described.
`As shown in FIGS. 6A and 6B, gate electrodes 142
`55 composed of refractory metal such as Cr or Mo are formed
`on the insulator substrate 110 made of quartz glass, non(cid:173)
`alkali glass, or a similar material.
`Further on top, a gate insulating film 112 and an active
`layer 141 composed of p-Si film are sequentially formed.
`The active layer 141 is provided with intrinsic or sub-
`stantially intrinsic channels 14 lc formed above the gate
`electrodes 142. The source 141s and drain 141d are formed
`on respective sides of these channels 141c by performing ion
`doping with p-type impurities such as boron (B) while
`65 covering those respective sides with a resist.
`An interlayer insulating film 115 formed by sequential
`lamination of a SiO2 film, a SiN film, and a SiO2 film is
`
`45
`
`The display device of the present invention will now be
`described.
`FIG. 4 is a plan view illustrating one display pixel in an
`organic EL display device implementing the present inven(cid:173)
`tion. FIG. 5 is a diagram showing an equivalent circuit for
`a plurality of display pixels of the organic EL display device.
`Each of FIGS. 6A and 6B shows a cross-sectional view
`taken along line B-B in FIG. 4. A separate drawing for the
`cross-sectional view taken along line A-A of FIG. 4 is not
`included because this view is identical to the previously
`described FIG. 3A.
`In the present embodiment, TFTs having gate electrodes
`disposed underneath the active layer 131, namely, bottom(cid:173)
`gate type TFTs, are employed as the first and second TFTs
`130,140. The TFTs of the present embodiment use a p-Si
`film as the active layers, and include gate electrodes 132,142
`comprising the double-gate structure.
`The organic EL display device is configured by sequen(cid:173)
`tially forming layers of TFTs and organic EL elements on a
`substrate 110 made of a material such as glass or synthetic
`resin, or alternatively on a conductive or semi-conductor
`substrate having an insulating film of SiO2 , SiN, or a similar
`material on its surface.
`As shown in FIGS. 4 and 5, each display pixel is formed
`in a region surrounded by gate signal lines 151 and drain
`signal lines 152. The organic EL display device is formed by 60
`arranging display pixels having organic EL elements 160
`and TFTs 130,140 on the substrate 110 in a matrix.
`The first TFT 130 is disposed near a intersection of the
`two signal lines 151, 152. The source 131s of the TFT
`simultaneously functions as a capacitor electrode 155 which,
`together with the opposing storage capacitor electrode 154,
`forms a storage capacitor. The source 131s is connected to
`
`50
`
`LG Display Co., Ltd.
`Exhibit 1014
`Page 011
`
`

`

`US 6,724,149 B2
`
`20
`
`7
`provided on the entire surface over the gate insulating film
`112 and the active layer 141. A contact hole formed in a
`position corresponding to the drain 141d is filled with metal
`such as Al, forming a power source line 183 connected to a
`power source input terminal 180. Further, a planarizing
`insulating film 117 made of an organic resin or a similar
`material is formed over the entire surface for planarization.
`A contact hole is formed in the planarizing insulating film
`117 in a position corresponding to the source 141s. A
`transparent electrode made of ITO that contacts the source 10
`141s through this contact hole, namely, the anode 161 of the
`organic EL element, is formed on the planarizing insulating
`film 117.
`The organic EL element 160 is configured such that an
`emissive element layer 166 is interposed between the anode
`161 and the cathode 167. In the present embodiment, the
`anode 161, the emissive element layer 166, and the cathode
`167 are formed in that order on top of the planarizing
`insulating film 117. According to the present embodiment,
`the emissive element layer includes an organic compound as
`its component. The emissive element layer is constituted by
`forming, in order, a first hole-transport layer 162, a second
`hole-transport layer 163, an emissive layer 164, and an
`electron-transport layer 165.
`The anode 161 is, as mentioned above, a transparent
`electrode formed using ITO. The first hole-transport layer
`162 is composed using MTDATA(4,4',4"-tris(3-
`methylphenylphenylamino )triphenylamine ). The second
`holetransport layer 163 is composed using TPD (N,N'(cid:173)
`diphen y 1-N ,N'-di( 3-meth y 1 phen y 1)-1, 1' -biphen y 1-4,4' -
`diamine). The emissive layer 164 is formed using quinac(cid:173)
`ridon derivatives and Bebq2 (bis(lO-hydroxybenzo[h]
`quinolinato) beryllium). The electron transport layer 165 is
`composed using Bebq2 . The cathode 167 is made of a
`magnesium-indium alloy. The cathode 167 is formed as a 35
`common electrode covering the entire surface of the sub(cid:173)
`strate 110 on which the organic EL display device is
`disposed, or covering at least the display region. It should be
`noted that the configuration and component materials of the
`organic EL elements 160 are not limited to the above- 40
`mentioned examples, and that other configurations and
`materials may similarly be used.
`Next explained are the power source lines (main power
`source lines) 183 and the power source bypass lines (bypass 45
`power source lines) 181 for supplying drive current (power)
`to the above-described organic EL elements 160 via the
`input terminals 180. FIGS. 6A and 6B illustrate examples of
`bypass lines 181 formed by different manufacturing pro-
`cesses.
`Each power source line 183 is arranged within the display
`pixel region in parallel with the drain signal lines ( data lines)
`153 along the column direction, as shown in FIG. 4. Each
`power source line 183 is connected to display pixels
`assigned as forming one column, and supplies drive current 55
`from the power source input terminal 180 to the organic EL
`elements 160 via the second TFTs 140.
`In the present invention, the power source lines 183
`disposed for each column between display pixels are elec(cid:173)
`trically connected by bypass lines 181 arranged along the
`horizontal direction in FIG. 4 (the row direction), providing
`a circuit configuration having a grid pattern within the
`display pixel region. In the related art wiring configuration
`shown in the previously-described FIG. 2, the distance along
`the column direction from the power source input terminals
`180 to display pixels imposed a restriction on the power
`(current) that can be supplied to the display pixel. However,
`
`8
`by providing the bypass lines 181 along the row direction as
`in the present embodiment, the display pixels can simulta(cid:173)
`neously receive current supply along the row direction via
`the bypass lines 181. Accordingly, in one row, the plurality
`5 of power source lines 183 arranged along the column
`direction can be maintained approximately at the same
`potential, reducing the dependency of power to be supplied
`to each display pixel on the distance from the input terminal
`180.
`The bypass lines 181 are formed using a low-resistance,
`conductive material such as Al. The bypass lines 181 can be
`integrally formed in one process with the power source lines
`183 on the interlayer insulating film 115 as shown in FIG.
`6A, by forming line on the substrate in a grid pattern. The
`15 lines 183 and 181 may alternatively be formed in different
`processes and connected via contact holes 182. In either
`case, to prevent short-circuiting at the intersections with the
`drain signal lines 152 formed on the interlayer insulating
`film 115 similar to the power source lines 183 and the bypass
`lines 181, it is necessary to provide insulating fi