United States Patent (19)
`Utsugi et al.
`
`USOO567O792A
`Patent Number:
`11
`45 Date of Patent:
`
`5,670,792
`Sep. 23, 1997
`
`54 CURRENTCONTROLLED LUMINOUS
`ELEMENT ARRAY AND METHOD FOR
`PRODUCING THE SAME
`(75) Inventors: Koji Utsugi, Naoyasu Ikeda, both of
`Tokyo, Japan
`8.
`73) Assignee: NEC Corporation, Tokyo, Japan
`
`21 Appl. No.: 321,608
`22 Filed:
`Oct. 12, 1994
`-
`30
`Foreign Application. Priority Data
`Oct. 12, 1993
`JP
`Japan .................................... 5-253866
`(51
`int.C. ... G09G 3/30
`52 U.S. Cl. .............................. 257/59;257.f40; 313/504;
`313/505; 340/825.81; 34.5/76; 34.5/80; 34.5/206
`58) Field of Search ................................. 257/40, 59,72;
`313/504,505; 34.5/206, 76,91, 58, 80;
`340,825.81
`
`(56)
`
`as ways
`
`guisa
`
`DX
`
`2-196475 8/1990 Japan ....................................... 257/40
`4-297076 iO/1992 Japan ....................................... 257/40
`0553950A2 8/1993 Japan.
`OT
`PUBLICATIONS
`Howard, W.E., "Active-Matrix Techniques for Displays.”
`Proceedings for the Society for Information Display (SID)
`vol. 27, No. 4, 1986, pp. 313-326
`Japan Display '89, pp. 704-707, entitled "Matrix-Ad
`dressed Organic Thin film EL Display Panel”.
`EuroDisplay '90, pp. 216-219, entitled “Design of a Proto
`type Active Matrix CdSe TFTAdressed EL Display".
`European Search Report.
`Primary Examiner-Jerome Jackson
`Assistant Examiner-John Guay
`Attorney Agent, or Firm-Whitham, Curtis, Whitham &
`McGinn
`ABSTRACT
`57
`S
`57
`In a current-controlled luminous element array, combina
`tions of a luminous element of a current-controlled type, a
`current-controlling transistor for controlling the current of
`References Cited
`the luminous element, and a switching transistor are
`ATENT
`UME
`arranged in a matrix form between signal electrode lines and
`U.S. P.
`DOC
`NTS
`Scan electrode lines such that the luminous element is
`2,965,802 12/1960 Loebner .................................... 34.5/81
`connected at one terminal thereof to a power source elec
`3,621,321 11/1971 Williams ...
`313/504
`E. E. ?t
`315. trode line and at the other terminal thereof to a drain
`5,220,316 6/1993 Kazan ...........
`340,784
`electrode of the current controlling transistor, a gate elec
`5,294.811
`3/1994. A
`trode of the current-controlling transistor and one signal
`saw-
`oyama et al. ......
`... 257/59
`-
`s
`5,343,050 8/1994 Egusa et al. ..........
`electrode line have the switching transistor connected
`... 257/40
`5,408,109 4/1995 Heeger et al. ...
`... 257/40
`therebetween, and the current-controlling transistOr in an
`5,514,878 5/1996 Holmes et al. ........................... 257/40
`arbitrary column of matrix has a source electrode thereof
`connected to one scan electrode line in another column.
`FOREIGN PATENT DOCUMENTS
`2488O16 7/1980 France.
`
`14 Claims, 6 Drawing Sheets
`
`54 HOENECONELECTROE
`EAS
`52A, HOLE NJECTION LAYER
`52B ORGANIC LUMINESCENT LAYER 52"
`52C SPACERAYER
`
`
`
`
`
`1.
`SGNA
`EEE
`NE
`
`c
`CAPACIFOR
`
`
`
`56
`T
`cSt
`
`t
`
`---
`
`3rd
`
`/ isos
`IT
`HII WD
`f
`
`---wop
`W
`
`wa-
`
`A N
`
`SAMSUNG EX. 1003 - 1/13
`
`

`

`U.S. Patent
`U.S. Patent
`
`
`
`Sep. 23, 1997
`Sep. 23, 1997
`
`FIG.1 PRIORART
`
`Sheet 1 of 6
`Sheet 1 of 6
`
`5,670,792
`5,670,792
`
`SAMSUNG Ex. 1003 - 2/13
`
`SAMSUNG EX. 1003 - 2/13
`
`

`

`USS. Patent
`
`Sep. 23, 1997
`
`Sheet 2 of 6
`
`5,670,792
`
`Lot
`oO
`ZO
`on
`=e!
`oO _j—
`oul
`©
`™
`
`||
`
`io
`—
`5
`Q
`o
`S/
`
`co
`oO
`
`a
`+
`
`T
`
`bo
`G
`oe
`tu fe
`uw
`—
`dota
`© fu
`re OF
`@ 72
`mo 3
`)
`a1 =
`<
`=z
`©
`@
`t
`—
`oO
`ry
`
`Li
`oO
`OF
`tu)
`On
`AO
`aE
`to
`om
`od
`lo
`O°
`
`Lo
`oO
`oO
`oe
`
`SGZOu
`onZ
`Hus]
`
`= Q
`
`FIG.2 PRIORART
`
` ©m
`
`|
`
`=
`
`PICTUREELEMENT
`
`m)—
`
`SAMSUNG Ex. 1003 - 3/13
`
`SAMSUNG EX. 1003 - 3/13
`
`

`

`US. Patent
`
`Sep. 23, 1997
`
`Sheet 3 of 6
`
`5,670,792
`
`tJ
`
`A
`=)
`>
`
`ww
`
`=z
`mr
`
`Oo
`O
`=>
`
`z
`>=
`iS
`
`a wl!
`Qa O=
`>
`
`E
`aS
`ocr
`
`=O
`
`n
`
`||
`
`|
`
`Qo
`
`O
`ox
`aed
`
`©L
`
`u
`—_l
`
`i zS
`
`-n
`
`z
`nal
`7
`SN f
`
`
`
`im+1SIGNALELECTRODELINE
`
`
`
`
`
`
`
`SIGNALELECTRODE
`
`IMCINE
`
`FIG.3
`
`-
`
`L
`
`io
`1 _—_—se
`
`cry
`
`PICTUREELEMENT
`
`10
`
`SAMSUNG Ex. 1003 - 4/13
`
`SAMSUNG EX. 1003 - 4/13
`
`

`

`U.S. Patent
`
`Sep. 23, 1997
`
`Sheet 4 of 6
`
`5,670,792
`
`F I. G. 4
`5N SCAN ELECTRODE LINE
`
`
`
`SQL SOURCE
`ELECTRODE
`-Gol GATE
`
`-Do DRAIN
`ELECTRODE
`
`GATE
`GQSELECTRODE
`
`SAMSUNG EX. 1003 - 5/13
`
`

`

`U.S. Patent
`
`Sep. 23, 1997
`
`Sheet 5 of 6
`
`5,670,792
`
`WHOIS1(wug9z9)\LOVLNOOIaasvaSsy7906IODAalvo\WI
`qqouLosigAtJIOH
`
`INOmd
`ZAAZZZRKQQEDSEKPDIPDPDPLPttKASEELEALEER4);
`
`
` aAAA WLAN2S}NAVTLNZOSANINNTOINVONO82s
`
`
`
`JINVONOYIAVTNOLLOAPNIFIOHVZS
`00a3aqouLgg1330UNOS
`
`NEOSSEAN
` JGOYXLOATANOLOSPNIFIOH¥SGO14
`
`
`
`(UOL49)
`
`SAMSUNG Ex. 1003 - 6/13
`
`SAMSUNG EX. 1003 - 6/13
`
`
`
`
`

`

`U.S. Patent
`
`Sep. 23, 1997
`
`Sheet6 of 6
`
`5,670,792
`
`Lu
`
`©5
`
`Lu
`Ca
`
`m8
`Lars
`Fry
`On
`z ou
`LO
`»
`
`“
`Oo
`F
`=)
`cy Ln
`Ou
`oT]
`Va
`1
`=
`z
`ns
`
`Lu
`oO
`©
`ie
`SSZu
`On
`AT
`
`+=
`
`a
`i)
`toe
`<k
`Su
`Cue
`Ati
`=
`
`FIG.6
`
`a
`S
`=>
`
`-
`+
`my
`
`a
`>
`
`0
`
`7
`or
`5h)
`r=
`Oly
`an
`~O
`
`N
`
`SAMSUNG Ex. 1003 - 7/13
`
`SAMSUNG EX. 1003 - 7/13
`
`

`

`5,670,792
`
`1
`CURRENTCONTROLLED LUMNOUS
`ELEMENT ARRAY AND METHOD FOR
`PRODUCING THE SAME
`
`BACKGROUND OF THE INVENTION
`The present invention relates to a current-controlled lumi
`nous element array and a method for producing the same,
`and in particular to a current-controlled luminous element
`array of an active matrix type such as for a display purpose,
`having multiple current-controlled luminous elements
`arranged in a matrix form, and a method for producing the
`S8,
`
`10
`
`2
`positive drive pulse voltage V to all signal lines 151 during
`the selected period of time. A pulse driving with a drive
`pulse voltage within a range of 20 V to 30 V and at a duty
`of 3.5% gives aluminance within a range of 20 cd/m’ to 30
`cd/m. The luminescence response speed to on-off actions of
`the drive pulse is lower than 10 us. In such pulse driven
`cases, the luminance is proportional to the drive pulse
`duration.
`The simple matrix type EL panel using the organic
`thin-film EL element in concern also shows a characteristic
`that the luminance increases in proportion to the drive pulse
`duration, as described. Therefore, an increased number of
`scan lines requiring a drive pulse higher of duty and smaller
`of duration would cause a problematic insufficiency of
`luminance per pulse. A limitation is thus given to the
`increase in number of scanlines. The reduction of luminance
`due to a high raised duty might be compensated by using a
`high raised drive pulse voltage, which however interferes
`with a sufficient utilization of the voltage stabilizing advan
`tage the organic thin-film EL element otherwise would
`permit. Still worse, the use of a voltage high-raised drive
`pulse may aggravate the aging of organic thin-film EL
`element, causing the charge injection efficency and the
`luminous efficiency to be both lowered with time, thus
`failing to keep a stable luminance that would be achieved
`under a stable drive voltage.
`The luminance reduction with a high raised duty is due to
`a very high luminescence response speed of the organic
`thin-film EL element in comparison with the imposed pulse
`thereon. This is because the organic thin-film EL element
`has no memory nature in the luminescence mechanism. To
`have a matrix type organic thin-film EL panel with a plenty
`of scan lines luminesce under a stable voltage and with a
`high luminance, it accordingly is necessary to have a devised
`drive circuit such that a stable voltage is kept imposed on an
`associated organic thin-film EL element over a sufficient
`length of time, i.e., it is needed to provide an organic
`thin-film EL element combined with a drive circuit adapted
`to have its own memory nature.
`A drive circuit so adapted is reported in the EURODIS
`PLAY '90, a collection book of prepared papers published
`by the Society for Information Display, at pages 216 to 219.
`FIG. 2 is a circuit diagram of a number of organic thin-film
`EL elements employed as current-controlled luminescent
`elements in a luminous element array reported in this
`collection book, while for the convenience of description no
`more than a portion of two rows crossing over two columns
`is shown in the figure.
`As shown in FIG. 2, the luminous element array has,
`among a matrix of unit pixels or picture elements, an
`arbitrarily taken one 130 at a place where an (N+1)-th
`element row intersects an M-th element column, that com
`prises a luminescent element EL (an organic thin-film EL
`element) of a current-controlled type of which the luminance
`is controlled in dependence on the current conducted
`therethrough, a current-controlling transistor Q, for control
`ling the current of the luminescent element EL, a charge
`holding capacitor C, and a switching tansistor Qs. To permit
`selecting an arbitrary one of the picture elements in the array,
`a scan electrode line is provided for each row, and a signal
`electrode line for each column. For example, in FIG. 2, the
`picture element 130 disposed at the intersection of the
`(N+1)-th row with the M-th column is selectable by con
`currently selecting a scan electrode line 103 common to
`a plurality of picture elements constituting the (N+1)-throw
`and a signal electrode line 101 common to a plurality of
`picture elements constituting the M-th column. The lumi
`
`15
`
`20
`
`25
`
`30
`
`DESCRIPTION OF THE RELATED ARTS
`As conventional current-controlled luminous elements
`there are well known EL(electroluminescent) elements,
`LED(light emitting diode)'s, etc. In particular, the organic
`EL element of a charge injection type employing a thin
`filmed organic luminescent material as an illuminant, here
`inafter called "organic thin-film EL element”, is attracting
`attentions for the possibility of realizing an inexpensive
`full-colored wide display that would be difficult by using an
`inorganic thin-film EL element or an LED. There will be
`described the constitution of a conventional typical current
`controlled luminous element array in an EL panel using an
`organic thin-film EL element.
`The organic thin-film EL element is a current-controlled
`luminescent element of the type that is constituted with an
`organic luminescent layer consisting of an organic coloring
`matter strong of luminescence and a charge injection layer,
`the layers being formed between a pair of electrodes either
`or both transparent (or translucent), and that gives an effec
`tive luminescence due to the recombination between
`injected electrons and positive holes from the electrodes. An
`35
`essential feature of the organic thin-film EL element resides
`in that, with a lower voltage than a level near 10 V, a higher
`luminance than a level near 1000 cd/m is easily obtainable
`in addition to that a high luminous efficiency is achieved in
`a range over several lumens per watt (subject to a direct
`current driving). Such the luminous performance stands
`beyond those of inorganic thin-film EL elements.
`An example of utilization of the high luminous perfor
`mance is reported in the JAPAN DISPLAY'89 published by
`the Society for Information Display, at pages 704 to 707, in
`which an organic thin-film EL element is applied to a dot
`matrix display.
`FIG. 1 is a perspective sectional view of a display
`oriented organic thin-film EL panel in the example reported
`in the above JAPAN DISPLAY 89, a collection book of
`prepared papers. According to the collection book, the
`shown EL panel has, on a glass base 150, a plurality of signal
`lines 151 extending parallel to one another, an organic
`thin-film layer 152 as an illuminant layer, and a plurality of
`scan lines 153 crossing over the signal lines 151, formed in
`this order. The organic thin-film layer 152 has a dual layer
`structure consisting of a hole injection layer 152A formed
`over the signal lines 151, and an organic emission layer
`152B laminated on the hole injection layer 152A. The signal
`lines 151 are made of a transparent electrode material ITO
`(indium tin oxide), so that the generated light in the organic
`thin-film layer 152 can be emitted through the transparent
`signal lines 151 outside the glass base 150. The panel driving
`of the display in concern is performed in a so-called simple
`matrix line sequencing manner. That is, the scan lines 153
`employed as common lines are sequentially selected one by
`one, and each selected scan line continuously applies a
`
`45
`
`50
`
`55
`
`65
`
`SAMSUNG EX. 1003 - 8/13
`
`

`

`5,670,792
`
`15
`
`25
`
`30
`
`35
`
`3
`nescent element EL is given a power supply voltage V via
`a power source electrode line 105 for elements in the same
`OW.
`When in FIG.2 the scan electrodeline 103 is selected,
`the switching transistor Q is turned on. Then, a voltage on
`the signal electrode line 101 is imposed via the switching
`transistor Qs on the charge holding capacitor C. Following
`this condition, if the scan electrode line 103
`enters a
`non-selected state, the switching transistor Qs turns off and
`the capacitor C holds the imposed voltage thereacross. The
`capacitor C then has its terminal voltage applied between a
`gate and a source of the current-controlling transistor Q, so
`that, depending on a drain current vs. gate voltage charac
`teristic of the transistor Q, a current is conducted from the
`power supply electrode line 105 through the luminescent
`element EL and the transistor Q, to a common electrode line
`106, making the luminescent element EL luminesce. It
`therefore is possible to make the luminescent element EL
`luminesce with a preset luminance determined from a rela
`tionship between the luminance of the element EL and the
`imposed voltage on the capacitor C. Moreover, the applied
`voltage between the gate and the source of the current
`controlling transistor Q is maintained by a quantity of stored
`charges in the capacitor C, at a substantially constant voltage
`for a predetermined time period. In the luminous element
`array in concern in which the drive circuit of each lumines
`cent element exhibits such a memory nature as described,
`even if a drive pulse is imposed with a narrowed pulse
`duration for a high raised duty, the luminance of the lumi
`nescent element EL is prevented from lowering according
`thereto. It is unnecessary for the prevention of luminance
`reduction to raise the supplied voltage (V from the power
`source electrode line 105 in this case) to the luminescent
`element EL.
`The luminous element array shown in FIG. 2 has the
`capacity C provided for the gate of the current-controlling
`transistor Q. The capacitor Cmay be replaced by a parasitic
`or barrier capacitance between the gate and the source of the
`transistor Q in consideration of circuit conditions such as a
`charge holding time.
`The luminance-stabilized luminous element array, in
`which the picture elements are arranged in a matrix form, is
`yet disadvantageous in that the image quality is subject to
`deteriorations due mainly to broken, disconnected or short
`circuited wiring lines. In general, the frequency of occur
`rence of such accidents increases as the line length or the
`number of line-on-line intersections increases. In the lumi
`nous element array shown in FIG. 2, it is needed for driving
`the picture element 130 to provide four types of common
`lines. i.e. the signal electrode line 101, the scan electrode
`line 103, the power source electrode line 105 and the
`common electrode line 106. As a result, there appear as
`many as four intersections denoted by a o mark within a
`region of the single picture element 130 shown in FIG. 2. As
`will be seen from this case, the number of common lines
`constitutes an essential factor in the art: if increased even by
`a smallest number, it will invite a significant increase in both
`total length of lines and total number of line-on-line
`intersections, thus resulting in an increased probability of
`occurrences of line breakage, disconnection and short
`circuit, causing the non-defective unit productivity to be
`reduced.
`
`45
`
`50
`
`55
`
`SUMMARY OF THE INVENTION
`It is therefore an object of the present invention to provide
`a current-controlled luminous element array of a high qual
`
`65
`
`4
`ity active matrix type having a significantly reduced ten
`dency to image quality deteriorations due to common line
`breakage, disconnection and short circuit, and a method for
`producing the same.
`To achieve the object, the present invention provides a
`current-controlled luminous element array in which a plu
`rality of combinations of a luminous element of a current
`controlled type provided with a pair of terminals, a current
`controlling transistor for controlling the current of the
`luminous element, and a switching transistor are arranged in
`the form of a matrix between a plurality of signal electrode
`lines and a plurality of scan electrode lines such that the
`luminous element is connected at either terminal thereof to
`a power source electrode line and at the other terminal
`thereof to a drain electrode of the current-controlling tran
`sistor and that a gate electrode of the current-controlling
`transistor and one signal electrode line have the switching
`transistor connected therebetween, wherein the current
`controlling transistor in an arbitrary one of a plurality of
`columns of the matrix has a source electrode thereof con
`nected to one scan electrode line in another column.
`Preferably, the drain electrode of the current-controlling
`transistor and the gate electrode thereof have a charge
`holding capacity connected therebetween, and more
`preferably, the luminous element has a diode installed in a
`current conducting route thereof and oriented in the forward
`direction thereof.
`Moreover, the luminous element may preferably comprise
`a charge injection type organic thin-film EL element includ
`ing at least one organic luminescent layer, and/or the
`current-controlling transistor may preferably comprise an
`amorphous silicon thin-film transistor of a reversely stag
`gered type.
`Further, it may provide a preferable effect that said
`another column be the previous one to the arbitrary one in
`the order of the columns.
`According to the present invention, a current-controlled
`luminous element array has a current-controlling transistor
`in an arbitarary column of matrix-like arranged picture
`elements, connected at a source electrode thereof to a scan
`electrode line in another column, thereby eliminating a
`common electrode line that otherwise would be needed in
`each column. The elimination of wiring lines, even though
`the smallest in number of lines per column, permits a
`significant reduction in total line length and in number of
`intersections between lines in different layers of luminous
`element array, which effectively lowers the probability of
`occurences of line breakage, disconnection and short circuit
`and improves the image quality of display.
`Moreover, according to an aspect of the invention, a diode
`is provided in such a direction that conducts a current in the
`forward direction of a luminous element. Therefore, even
`when a reverse voltage from a scan electrode line in a
`selected column is imposed across the luminous element in
`a non-selected column, no current is conducted through the
`luminous element, which is thus protected against undesired
`current and prevented from deteriration.
`Still more, to achieve the object, the present invention
`provides a method for producing a current-controlled lumi
`nous element array consisting of a plurality of thin-filmed
`picture elements arrayed in the form of a matrix having rows
`and columns, the picture elements each respectively having
`formed therein a corresponding part of a signal electrode
`line common to the picture elements in the same row, a
`corresponding part of a scan electrode line common to the
`picture elements in the same column, a corresponding part
`
`SAMSUNG EX. 1003 - 9/13
`
`

`

`5,670,792
`
`10
`
`15
`
`5
`of a power source electrode line common to the picture
`elements in the same column, a current-controlling transistor
`provided with a source electrode, a gate electrode and a
`drain electrode, a switching transistor provided in an inter
`connecting circuit between the corresponding part of the
`signal electrode line and the gate electrode of the current
`controlling transistor, and a luminous element controlled
`with a conducted current from the corresponding part of the
`power source electrode line to the drain electrode of the
`current-controlling transistor, comprising the steps of con
`necting the source electrode of the current-controlling tran
`sistor in the picture element in concern to the scan electrode
`line common to the picture elements in an arbitrary column
`other than the same column, and connecting the luminous
`element in the picture element in concern, at one terminal
`thereof, to the corresponding part of the power source
`electrode line in the same picture element and, at the other
`terminal thereof, to the drain electrode of the current
`controlling transistor in the same picture element.
`When applied to a matrix type organic thin-film EL
`20
`display, the present invention permits the number of picture
`elements to be significantly increased to have a high-quality
`vision with a low voltage and a high luminance.
`BRIEF DESCRIPTION OF THE DRAWENGS
`The objects, features and advantages of the present inven
`tion will become more apparent from consideration of the
`following detailed description, taken in conjunction with the
`accompanying drawings, in which:
`FIG. 1 is a perspective sectional view of a conventional
`simple matrix type display panel using an organic thin-film
`EL element;
`FIG. 2 is a partial circuit diagram of a conventional
`current-controlled luminous element array;
`FIG. 3 is a partial circuit diagram of a current-controlled
`luminous element array according to a first embodiment of
`the invention:
`FIG. 4 is a partial plan view of the internal structure of a
`picture element in the first embodiment;
`FIG. 5 is a sectional view along line A-A of FIG. 4; and
`FIG. 6 is a partial circuit diagram of a current-controlled
`luminous element array according to a second embodiment
`of the invention.
`
`25
`
`6
`row, and a charge holding capacitor C in the same picture
`element 10 has one electrode thereof, i.e. one of two
`electrodes thereof at the opposite end to the other connected
`to a gate electrode of the transistor Q, connected to the same
`scan electrode line 3. In other words, in the first
`embodiment, exemplarily in the case of the picture element
`10 disposed in an (N+1)-th row, at an M-th column, the
`above-mentioned electrodes of the transistor Q and the
`capacitor Care both connected to the scan electrode line 3
`in the adjacent previous row (N-th row), like respective
`cases of other picture elements in the array, whereas in the
`case of the example of FIG. 2 the conventional luminous
`element array has corresponding electrodes in each picture
`element, both connected to the common electrode line 106.
`The first embodiment will be further described with
`respect to the plan layout, sectional structure, etc. FIG. 4 is
`a partial plan view mapping the layout of component ele
`ments in a square region of the picture element 10 shown in
`FIG. 3. That is, the lay out of the charge holding capacitor
`C, the current-controlling transistor Q and a switching
`transistor Qs disposed in a four-sided picture element region
`enclosed with scan electrode lines 3 and 3 and signal
`electrode lines 1 and 1, in FIG. 3. The luminescent
`element EL as a layered organic thin-film EL element
`extends over the capacitor C and the transistors Q and Qs,
`covering substantially the entirety of the picture element
`region, and is deleted from FIG. 4 to avoid a complicated
`drawing, except a later-described electron injection elec
`trode 55. FIG. 5 is a sectional view along line A-A of FIG.
`4, showing a detailed layer structure in a profile including
`the charge holding capacitor C and the current-controlling
`transistor Q as well as the organic thin-film EL element
`formed over them.
`Referring now to FIG. 5, each picture element has
`employed a pair of reversely staggered a-SiTFT's (the
`transistors Q, Qs) in combination with an organic thin-film
`EL element. The EL element includes an organic thin-film
`layer 52 of a three-layered structure having a spacer layer
`52C, an organic luminescent layer 528 and a hole injection
`layerS2Alaminated in this order over a glass base 50, on the
`a-SiTFT type current-controlling transistor Qin FIG.5. The
`spacer layer 52C is provided to prevent excitons from
`dissociating along the boundary surfaces of electrodes. On
`the organic thin-film layer 52 is formed a transparent hole
`injection electrode 54 using the transparent electrode mate
`rial TTO, which electrode 54 corresponds to a power source
`electrode line 5 shown in FIG. 3. Formed under the organic
`thin-film layer 52, i.e. on the side of a-SiTFT's, is the
`electron injection electrode 55 consisting of a metallic
`material MgAg. This electrode 55 is connected through
`second contacts in second contact holes 56B to a drain
`electrode Q of the current-controlling transistor Q.
`Among the described thin-film layers of the organic thin
`film EL element, the electron injection electrode 55 is
`patterned like an independent iland in each picture element
`region, while the organic thin-film layer 52 and the hole
`injection electrode 54 are made common to the whole
`picture elements of the luminous element array, i.e. formed
`over the entire region of a display panel. In the panel, when
`an arbitrary picture element is selected to be driven, there
`develops an electric field acting thereon, causing the organic
`luminescent layer 52B to luminesce, externally emitting flux
`of light through the transparent electrode 54.
`In the picture element in concern, as shown by a hatching
`in FIG. 4, from the scan electrode line 3, extending in the
`N-throw of the array a straight branch is extended perpen
`dicularly thereto, to thereby constitute a lower electrode of
`
`30
`
`35
`
`45
`
`DESCRIPTION OF THE PREFERRED
`EMBODEMENTS
`There will be detailed below preferred embodiments of
`the present invention, with reference to FIGS. 3 to 6. The
`embodiments, both the first and the second, have employed
`a pair of reversely staggered a-SiTFT(amorphous silicon
`thin-film transistor)'s as a switching transistor and a current
`controlling transistor, in combination with an organic thin
`film EL element as aluminescent luminous element, as later
`described.
`The first embodiment will be described first in respect of
`the circuitry. FIG. 3 is a partial circuit diagram of aluminous
`element array according to the first embodiment, showing a
`portion of two rows crossing over two columns in the array,
`like FIG. 2 showing a conventional example. The first
`embodiment is different from the conventional example in
`that, in the shown circuitry in FIG. 3, a current-controlling
`transistor Q in a picture element 10 in one row has a source
`electrode thereof, i.e. an electrode thereof at the opposite end
`to another connected to a luminescent element EL, con
`nected to a scan electrode line 3 in an adjacent previous
`
`SO
`
`55
`
`65
`
`SAMSUNG EX. 1003 - 10/13
`
`

`

`5,670,792
`
`O
`
`15
`
`20
`
`25
`
`7
`the charge holding capacitor C, and another branch from the
`same line 3 is connected through first contacts in first
`contact holes 56A to the source electrode S of the current
`controlling transistor Q. Thus, one electrode of the capacitor
`C in this picture element disposed in the (N+1)-th row and
`the source electrode of the transistor Q in the same picture
`element are both connected to the scan electrode line 3 in
`the N-th row, i.e. an adjacent previous row in the order of
`rows. For the switching transistor Qs in this picture element,
`the scan electrode line 3
`extending in the (N+1)-th row
`of the array provides a straight branch that constitutes a gate
`electrode Gas of the transistor Qs. Thus, the gate electrode
`Gs of the transistor Qs in this picture element disposed in
`the (N+1)-throw is connected to the scan electrode line 3
`in the same row.
`There will be described a method for producing the
`luminous element array according to the first embodiment,
`substantially in a limitted manner to the shown profile in
`FIG.S.
`First, on the glass base 50 is grown a Cr layer 200 nm.
`thick. Then, a patterining process is executed for the scan
`electrode lines 3 and 3, the lower electrode of the charge
`holding capacity C, the gate electrode Gas of the Switching
`transistor Qs and the gate electrode G of the current
`controlling transistor Q. An SiO2 layer is letto grow 400 nm.
`to provide a gate insulation, before an etching to open the
`first contact holes 56A.
`Thereafter, an i-a-Si (intrinsic amorphous silicon) layer is
`let to grow 300 nm on the SiO, and an n-a-Si (n" amor
`30
`phous silicon) layer for ohmic contact use is let to grow 50
`nm. The grown layers are concurrently pattern-processed to
`define small islands of a-SiTFT. The islands will have
`channels formed therein for the transistors Q and Qs in a
`later process.
`Then, a Cr layer 100 nm thick is deposited and pattern
`processed to provide the signal electrode line 1, the source
`electrode S and the drain electrode D of the current
`controlling transistor Q, a drain electrode and a source
`electrode of the switching transisitor Qs, an upper electrode
`of the charge holding capacitor C and the first contacts. The
`channels of the transistors Q and Qs are then formed by
`etching the a-SiTFT islands consisting of the i-a-Si layer
`covered with the n-a-Silayer, into an intermediate depth of
`the i-a-S layer, using the pattern-processed Cr layer as a
`mask.
`Then, a SiO2 layer is let grow 200 nm, before an etching
`to open the second contact holes 56B for intercommunica
`tion between the source electrode S of the current
`controlling transistor Q, and the electron injection electrode
`55 to be formed as a lower electrode of the organic thin-film
`EL element in the subsequent process.
`Then, an MgAglayer is let to grow 200 nm and processed
`by a lift-off method for a patterning to form the electron
`injection electrode 55. By the procedures described, there is
`produced a panel member having 400x640 picture element
`regions of a size of 100x300 um/element.
`Then, on the panel member is formed the organic thin
`film layer 52 of the organic thin-film EL element. The
`organic thin-film layer 52 has a three-layered structure
`consisting of the spacer layer 52C for preventing the disso
`ciation of excitons along the boundary surafces of
`electrodes, the organic luminescent layer 52B and the hole
`injection layer 52A, laminated in this sequence on the
`electron injection electrode 55, as described. To form the
`spacer layer 52C, vaporized tris-(8-hydroxynolin) alu
`minium is vacuum deposited 50 nm. Thereafter, tris-(8-
`
`SO
`
`8
`hydroxynolin) aluminium and 3.9-perylene dicarbonyl acid
`diphenyl ester from different vacuum vapor sources are
`codeposited 70 nm to form the organic luminescent layer
`52B. Then, 1.1-bis-(4-N,N-ditolyl aminophenyl)cyclohex
`ane vaporis deposited 50 nm to form the hole injection layer
`S2A.
`As a final process, the hole injection electrode 54 is
`formed as a layer 1 m thick, by coating the organic
`thin-film layer 52 with the transparent electrode material
`TO.
`The first embodiment will be still described, with respect
`to the action. In FIG. 3, if the scan electrode line 3
`is
`selected, the switching transistor Q is turned on. The signal
`electrode line 1 in the M-th column then has a line voltage
`thereof imposed via the switching transistor Qs on the
`charge holding capacitor C.
`enters a non
`Thereafter, the scan electrode line 3
`selected state. The switching transistor Qs then turns off, and
`the charge holding capacitor C holds thereacross the
`imposed voltage from the signal electrode line 1. The
`capacitor Cthus has its terminal voltage applied between the
`gate and source electrodes of the current-controlling tran
`sistor Q so that, according to a drain current vs. gate voltage
`characteristic of the transistor Q, an electric current runs
`through an established conducting route: the power source
`electrode line 5->the luminescent element EL-the transis
`tor Q-)the scan electrode line causing the luminescent
`element EL to luminesce. The luminance of the luminescent
`element EL is controllable at a preset level, by using a
`relationship thereof to the imposed voltage on the capacitor
`C.
`An experiment of the first embodiment was made. The
`organic thin-film EL element exhibited a luminance of
`approx. 200 cd/m with a drive voltage of 7 V applied
`thereacross, while the current density therein was approx.
`0.8 mA/cm. The total power consumption in the organic
`thi