United States Patent [191
`Koma
`
`1111111111111 m 111111111111111111 11111 11111111111111111111111111111 1111
`USOO5608556A
`[Ill Patent Number:
`[45] Date of Patent:
`
`5,608,556
`Mar. 4, 1997
`
`[54] LIQUID CRYSTAL DISPLAY HAVING
`ORIENTATION CONTROL ELECTRODES
`FOR CONTROLLlNG LIQUID CRYSTAL
`ORIENTATION
`
`5,475,517 12/1995 KonllllIll el al. .....
`
`....... 359n5
`
`FOREIGN PAlENT DOCUMENTS
`
`0058029
`
`211990
`
`Japan
`
`.............................. 359n2
`
`[751
`
`Inventor: Norio Koma, MOlosu-gun, Japan
`
`OTHER PUBLICATIONS
`
`[73] Assignee: Sanyo Electric Co" Ltd., Osaka, Japan
`
`(21] Appl. No.: 263,871
`
`(22]
`
`Filed:
`
`JUD. 21, 1994
`
`PO]
`
`Foreign Application Priority Data
`
`Jun. 24, 1993
`Jul. 8. 1993
`Nov. 25, 1993
`Apr. 28, 1994
`
`[II'J
`[IP]
`[IP]
`[JP]
`
`. .......... 5-153671
`Japan ..........
`Japan ................................... 5-169087
`Japan ..... .................•.......... 5-295731
`Japan
`..................... 6-092283
`
`[5 1]
`
`Int. Cl.6
`
`.............. ........... G02F 111343; G02F 1/135;
`G02F 1113]7
`[52] U S . CI •........................... 349/143; 349/42; 349/1 16;
`3491123
`359/54,59,75,
`359/87,72
`
`[58J Field of Searcb
`
`[561
`
`Re£erences Cited
`u.s. PATENT DOCUMENTS
`. ........... 359/87
`711988 Yanagisawa ..
`. .............. 359187
`&'1991 Suzuki ...
`6/1994 Ukai ct al .............................. 359159
`&'1994 Kim Cl aI ................................. 359159
`911994 Koseki et al. ........
`. ......... 359157
`
`4359,610
`5,042,918
`5,321,535
`:5,339,181
`5,345,324
`
`Lien, A., et a1., "Multi-domain homeotropic liquid crystal
`display for active mauix application", mM Researh Divi·
`sion, Yorktown Heights, N.Y., pp. 21- 24.
`
`Primary Examiner-Sara W. Crane
`Assistant Examiner-Fetsum Abraham
`AI/orney, Agent, or Finn- Loeb & Loeb LLP
`ABSTRACT
`[57J
`In a liquid crystal display of TfT active matrix type, the
`direction of orientation veclOrs of liquid crystal molecules
`arc controlled for providing a wide viewing angle and
`preventing occurrence of disclination from making a rough
`display screen. With an orientation control electrode dis(cid:173)
`posed on the periphery of a display electrode, an orientation
`control window, an electrode nonexistent portion, is formed
`in a common electrode and the potential difference between
`the orientation control electrode and the common electrode
`is sct smaller than that between the display electrode and the
`common clecuode. Alternatively, an orientation control win(cid:173)
`dow is likewise fonned in the display electrode and the
`potential dilference between the orientation control elec(cid:173)
`trode, and the common electrode is sel larger than that
`between the display electrode and the common electrode.
`
`22 Claims, 14 Drawing Sheets
`
`31
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`34
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`32
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`33a
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`30
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`11 ,. 15 16 22 18
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`19
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`13
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`17
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`21
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`10
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`Page 1 of 23
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`SHARP EXHIBIT 1014
`Sharp Corp., et al. v. Surpass Tech Innovation LLC
`IPR2015-00021
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`u.s. Patent
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`Mar. 4, 1997
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`Sheet I of 14
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`5,608,556
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`Fig. 1 PRIOR ART
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`Page 2 of 23
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`u.s. Patent
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`Mar. 4, 1997
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`Sheet 2 of 14
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`5,608,556
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`202
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`201
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`200
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`Fig. 2 PRIOR ART
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`Page 3 of 23
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`u.s. Patent
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`Sheet 3 of 14
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`Page 4 of 23
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`U.S. Patent
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`u.s. Patent
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`Mar. 4, 1997
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`U.S. Patent
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`Mar. 4, 1997
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`Sheet 6 of 14
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`Mar. 4, 1997
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`Mar. 4, 1997
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`u.s. Patent
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`Mar. 4, 1997
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`U.S. Patent
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`Mar. 4, 1997
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`Sheet 12 of 14
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`U.S. Patent
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`Mar. 4, 1997
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`Sheet 13 of 14
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`U.S. Patent
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`Mar. 4, 1997
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`Sheet 14 of 14
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`5,608,556
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`Page 15 of 23
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`

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`5,608,556
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`1
`LIQUID CRYSTAL DISPLAY HAVING
`ORIENTATION CONTROL ELECT RODES
`FOR CONTROLLING LIQUID CRYSTAL
`ORIENTATION
`
`BACKGROlJh'D OF THE INVENTION
`
`1. Field of the Invention
`This invention relates w a liquid crystal display and more
`particularly to a liquid crystal display which. provides a wide
`viewing angle and high display quality by controlling the
`orienlation of liquid crystal directors.
`2. Description of the Related Art
`Liquid crystal displays have the advantages of their small
`size, slim form, and low power consumption. Therefore, lS
`they are becoming increasingly commercially practical for
`usc in office automation machines, audio and visual
`machines, and the like. Particularly, the liquid crystal dis(cid:173)
`plays of the active matrix type using thin-film transistors
`(TFfs) as switch.ing elements, which can display high- 20
`definition dynamic images, are used for television displays,
`clC,
`To form the liquid crystal display, as shown in FIG. 1, a
`TIT substrate 2 comprising TITs, display electrodes, ctc.,
`disposed like a matrix on a transparent substrate sucb as
`glMs, and an opposed substrate 4 having common electrodes
`are affixed with a several ).Illl thick liquid crystal layer 3
`between, and both the substrates affixed to eaeh other are
`sandwiched between two polarization plates 1 and 5 per(cid:173)
`pendicular to each other in a polarization axis direction.
`The Tn substrate 2 has a structure in which TFfs are
`formcd around thc intersections of gate lines (scanning
`lines) and dmin lines (data linl.:S) and uisplay c1cctruUcs
`located like a matrix are connected to the 1FI's. The gate
`lines arc scanned and selectcd in order, thereby turning on all
`TfTs on the same scanning line. Data signals synchronized
`with the turning on of thc TFfs are supplied to the display
`electrodes on the drain lines. Thc common electrodes arc
`also set to a predetermined IXltential in synch ronization with
`gate line scanning, thereby appl)'ing a predetermined poten(cid:173)
`tial difference to display picture element capacitors formed
`by thc common electrodes and opposite display electrodcs
`for driving the liquid crystal.
`Particularly, in the liquid crystal display using the ECB
`(elcctrieally cuntrolled birefringence) system, voltage is
`applied to display electrodes and common elcctrodes for
`controlling the oricntation state uf liquid crystal directors
`and a birefringt:nce change is made in white light incident
`frum a light source to provide an nptical switch function. For
`examplc, a nematic crystal liquid having ncgati\·c anisotropy
`of dielectric COnStant is used as the liquid crystal layer 3 and
`the initial orientation of liquid crystal directors is sct to the
`direction \'ertical to the substrate face; the liquid crystal
`display of this type is called VAN (vertically aligned nem(cid:173)
`atic) type.
`In FIG. 1, white light incident from the TFT substrale 2
`is passed through the first polarization plate 1 and resul ts in
`linear polarization only. When no voltage is applied, the
`incidcnt linear polarization is not subjected to birefringence 60
`in the liquid cf)'stallayer 3. and thus is shut offby the second
`polarization plate 5 and black is displayed (normally black
`mode). When a predetermined voltage is applied to the
`liquid crystal layer 3, the orientation of the liquid crystal
`dircctors changes to the direction in which the orientation 6S
`vector of the liquid crystal mnleculcs having negative
`dielectric constant anisotropy approach a right angle with
`
`2
`the electric field direction. Since a liquid crystal has anisot(cid:173)
`roPy in refractivc index, the linear polarization incidcnt on
`the liquid crystal layer is subjected to birefringcnce and
`becomes elliptic IXllarization and light is transmitted through
`the second polarization plate 5. The transmitted light
`strenglh in the liquid crystal display depends on lhe voltage
`applied 10 the liquid crystal laycr. Therefore, gradation
`display is enabled by adjusting the applied voltage for each
`picture element; light and dark (monochrome) display at the
`10 picture clements is visible as a predetermined display image
`00 lhc entire display.
`In the VAN type, macromolecular films of polyimidc
`(SI Nx) are formed on the surfaces of both substrates 2 and
`4 and rubbing treaUIlent is applicd to the films. thereby
`giving a predetermined pretilt angle to the initial vertical
`orientation of the liquid crystal dircctors for controlling the
`orientation of the liquid crystal directors. Funher, for
`example, the opposed substrate 4 is formed with a color filter
`installcd on an optical path and the color capability is
`combined with the optical shutter effect of ECB to provide
`color display.
`FIG. 2 is a plan view showing a light transmission state
`when tile conventional liquid crystal display using the ECB
`system shown in H G. 1 is driven. Although not discussed in
`the descri ption given SO far, a shielding film made of metal,
`25 ctc., is normally fonned on the opposed substrate for shut(cid:173)
`ting off tranSmission of light except for openings 201
`corresporuiing to the picture elements arranged like a matrix.
`In the shield area 200, light leakage betwecn thc picture
`clements is prevented and the ~hi eld area 200 is displayed in
`30 black, thereby improving display contrast. In each opening
`201 , the transmission rate of light is controlled to provide the
`desired display; a black area called disclination 202 also
`occurs in the opening 201. When a plurality of areas diffcr
`in orientation vector of liquid crystal, the orientation of
`3~ liquid crystal directors is disarranged on boundaries between
`the areas, and the area indicating a transmission rate differ(cid:173)
`cot from lhat in other areas is the disdination.
`For liquid crystal directors in nematic phase, the orienta(cid:173)
`tion vector, when voltage is applied, is restricted only at an
`4ll angle with the electric field direction and the azimuth with
`the electric fiel d direction as an axis is released. 11mt is, with
`theeleclric field effcctonly, an orientation vector oriented to
`a plurality of directions obtained by rotating with the electric
`field direction as the axis of symmetry is possible. On thc
`45 other hand, the TIT substrate has electrode irregularities on
`the surface and surface orientation trcaLment is unevcn. An
`electric field in a lateral direction exists due to the potential
`difference betwecn the electrodes in a liquid crystal cell.
`Therefore, areas different in orientation vector of liquid
`50 crystal molecules occur in the cell. If an orientation vector
`error exists even partially, since liquid crystal has a con(cid:173)
`tinuum propeny, orientation vectors having an azimuth
`following the liquid crystal having the erroneou s orientation
`vectors extend over a certmn area. If sueh a phenomenon
`55 occurs at more than one place in the cell, more than one area
`bas orientation vectors which are the same in angle with the
`electric field direction, but differ in azimuth. On the bound(cid:173)
`aries betwcen the areas, thc light transmission ratc diffcrs
`from tnat in other areas, cauSing disclination to occur. If
`disc1ination of different fonn for each picture clement occurs
`frequcntly, the display screen will havc a rough surfare and.
`the cxpected color display will not be provided.
`If orientation vectors of liquid crystal molecules in each
`area become irregular in the display area, there is a chance
`that viewing angle dependency will arise.
`On tbe other hand, in i,he VAN type, I.:Ic., due to static
`electricity occurring during rubbing treatment, TIT thresh-
`
`Page 16 of 23
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`5,608,556
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`3
`old or mutual conductance shifl results in electrostatic
`discharge damage, etc.
`
`SUMMARY OF THE INVENTION
`
`4
`aligrunent margin can be SCt with the outer peripheral edge
`of the orientation eontrol electrode as a reference, thereby
`redueing the margin to alb substnltes for prevcoting Ihe
`aperture ratio of the liquid crystal display from lowering.
`An orielilation control window containing no electrode
`may be fonned in the picture element area of tbe common
`electrode or the ditplay electrode. No electric field occurs in
`the window portion and liquid crystal dir«:lors arc fi:a:ed to
`the initial orientalion state. Therefore, the orientation control
`10 eleetrode and window enable the orientation vectors of the
`liquid crystal molecules to be fixed in one direction near the
`orientation control electrode and wiodow. Because of the
`coruinuum property of liquid crystal, the orientation vectors
`of the liquid crystal molcCldcs in thc display electrode are
`
`I' aligned. Further, the orientation control window enables the
`
`It is therefore an object of the Im-cntion to provide a
`solution 10 the above-mentioned problems.
`To this end, according III the invention. there is provided
`a liquid crystal display comprising II first substrate and a
`second substrate. The first and second SUDstrates arc located
`facing each other with a liquid crystal layer therebetween.
`The display also includes II plurality of display electrodes
`located like a matrix and switching clements connected In
`the display electrodes. The display elements and the SWilCh(cid:173)
`ing clements arc fonned on the liquid crystal layer side of
`the first subslrate, and a common e1eeLrOde is fonned on lJ1e
`liquid crystal layer side of the second substrate, so that when
`a predetermined vcllage is applied to the liquid cryslallayer
`for display. TIll; improvement is orientation control clec(cid:173)
`(rocics fonned on the first substrate and whieh are electri(cid:173)
`cally insulated from the display electrodes. Also, a potential
`cJiITerent from that of lhe display electrode is applied to the
`orientation control electrode for controlling the orientation
`of the liquid crystal.
`ThU!, the orientation control electrodes to which a pOlen- 2S
`tial different from that of the display elcctrodes is applied arc
`provided, 50 that tnc electric field in liquid crystal cells can
`be sccurdy controlled according to the potential differences
`between the orientation control electrode and the common
`elcclrOdc t\nd between the display e1ecuode and the common 30
`clectrode. It is also made possible to specify the azimuth of
`orientation vectors of liquid crystal moleailes.
`The electric field direction in the liquid crystal cell is
`inclined toward a predetennined direction from the normal
`direction ofthe substrate according to the effective potential 3S
`difference between the display and oriematioo control c1cc(cid:173)
`trOOes. When a voltage is applied to the liquid crystal layer
`by both the electrodes, a predetermined angle occurs
`between the initial orientation direction of liquid crystal
`directors and the electric field direction. Thus, the liquid 4()
`crystal directors incline in a direction \0 increase the angle
`of the electric field direction with thc initial orientation
`direction in the shortest way. A determination is made 10
`only one orientation vector of the liquid crystal molecules.
`The orientation control electrodes may be fonned in all 45
`areas except the formation alea of the display electrodes or
`at least sUlTOunding the periphery of the display electrodes.
`If the orientation control electrode is located. so as to
`surround the pcrlphery of the display electrode, liquid crys- so
`tal directors are subjected 10 equal orientation control on
`four sides of the display electrode. The orientation vectors of
`liquid erystal molecules ineline at right angles to each side.
`Since the liquid crystal molecules havc a continuum prop(cid:173)
`erty, if the orientalion state is controlled on each ~ide of the 55
`display electrode, they arc aligned to substantially equal
`orienullion vCCl~ to the centCT of the displllY electrode.
`lberefore, display quality can be improved.
`If the orientation control electrodes are fonned in all areas
`e:a:ccpt the formation area of the display electrodes, light 60
`leakage in the non-display area can be prevented. eliminat(cid:173)
`ing the need for in&talling a shieldins film on tbe opposed
`substrate side.
`Funhcr, if the orientation control electrodes are fonned.
`partially o"erlapping the display elcctrodes, light leakage in
`the non.display area can be securely prevented. Therefore, if
`a shielding film is fonned on the oppored substrate side, an
`
`boundaries between areas different in azimuth of orientation
`vector, in the display urea 10 be fixed without variations
`from one picture element to another.
`If the orientation control window is formed in the picture
`20 element area of the common electrode, the elfcctivc poten·
`tial difference between the orientation control electrode and
`the common electrode is set smaller than that between the
`display electrode and the common elc."Ctrudt:. On the otber
`hand. if the orientation control window is fonned in the
`picture element area of the display electrode, the effective
`potential diffcrence between the orientation. control elec(cid:173)
`trode and the common elcclrode is set larger than that
`between tbe display electrode and the common electrode.
`Near the edge of the orientation control window, an
`electric field occurs slantingly from the electrode e:a:istent
`area to the electrode nonexistenl area in the liquid crySlai
`layer. That is, the electric field occurring from tbe clcctrode
`opposed to the oricntalion control window avoids the ori-
`cnUltion control window IUld moves lO the electrode existent
`portion.
`Therefore, the inclined direction of the electric field
`defined by the orientation control electrode and that defined
`by the orientation control window match in each zone of
`each picture element area. unifonnly defining the orientation
`state of the liquid crystal moleculcs.
`Particularly, if the orientation control window is formed
`like an X charactcr, the oricntation stale of each picture
`element area is divided into four equal zones. Therefore,
`when an image is displayed, transmitted light in the four
`zones is composed, providing a liquid crysllll display having
`low viewing angle dependency with four optimum viewing
`directions and a wide viewing angle.
`
`BRJEF DESCRIPTION OF 1liE DRAWINGS
`
`In the accompanying drawings:
`FIG. 1 is a suuerura.i drawing of a convaltional liquid
`crystal display:
`FIO. 2 is a plan view illustr:ating problCIDS on the con(cid:173)
`vemional liquid crystal display;
`FIG. J is 11 plan view of a liquid crystal display according
`to a first or second embodiment of the invention;
`FIG. 4 is a sectional view taken on line A-A in FIG. 3;
`AG. 5 is a sectional view ilIustratin~ the function and
`effect of the first embodiment;
`A o. 6 is a plan view illustrati ng thc function and effect
`6S of the first embodiment;
`l'lG. 7 is a plan vicw illustrating the function and efTect
`of the invention;
`
`Page 17 of 23
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`5,608,556
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`5
`FIG. 8 is a sectional view taken on line A- A in FIG. J;
`FIG. 9 is a scx:tional view illustrating 1hc function and
`effect of the second cmbodjme~;
`FIG. 10 is a plan view iIIuslrnting the function and effcct
`of the second embodiment;
`FIG. 11 is a plan view of aliquidcrystal display according
`to third and founh embodiments of the inve ntion;
`FIG. 1Z is a sectional view ukenon line 8 - B in FIG. 11;
`FIG. 13 is a sectional view of a structure different from 10
`FIG. 12, taken on line B-B in FlG. 11;
`Fro. 14 is a plan view of a liquid crystal display according
`to a fifth or sixth embodiment of the invention;
`FIG. 15 is a sectional "jew takcnon lineC-C in FIG. 14;
`~
`FIG. 16 is a sectional view taken on line C--C in FIG. 14.
`
`15
`
`Referring now to the accompanying drawings, there are
`shown preferred embodiments of the invention.
`A first embodiment of the invention will be discussed.
`FIG. 3 is a plan view of a 1FT substrate showing an
`electrode pallem of two picture elements. Gate Jines 12 and
`drain lines 20 are crossed on the substrate. A display
`elecuode 17 is located in the an:a surrounded by the gate
`lines 12 and the drain lines 20. A 1FT is formed at the
`intersection of both tIw!: linc~ 12 and 20 or around the
`intersection, and a source elccuodc: of !he 1FT 18 is con(cid:173)
`nected to the display electrode 17. An orientation control
`electrode 22 is located so as to surround !be periphery of the
`display electrode 17 and they are oonnectcd to each other in
`the row direction (the direction substantially parallel to the
`gate line). The X letter area indicated by the doued line in
`FIG. 3 denotes an oricnullion conlIOl window 33a formed as
`an electrode nonexistent portion at a common electrode
`formed on an opposed substrate (not shown). 'The orientation
`control window 33a corresponds to the display electrode on 40
`the 1FT substrate as a plane.
`A more detailed description will be given in conjunction
`with BG. 4, which is a sectional view taken on line A- A
`in FlG. 3. An about lsooA thick gate electrode 11 and gate
`line 12 formed by sputtering and pholoctching Cr, for
`example, arc located on a transparent substrate 10 such as
`glass. SiNx is laminated by CVD (chemical vapor deposi(cid:173)
`tion) on almost the full face of the substrate so as to cover
`the gate electrode 11 and gate line 12 to form a gate
`insulation film 13, which is about 2OOOA-4000A thick.
`Following the gate insulation film 13, a-SI (amorphous
`silicon) 14, etching stopper 15, and N'a-SI16 are laminated
`on the gate electrode 11 like an island by CVD film forming
`and photOCtching, whereby channel and contact layers ofthc
`TFT life formed. On the othcr hand, in a different areaon the 55
`gate insulation fi lm 13 where Ihe gate electrode 11 is not
`formed, an about IOOOA thick display electtode 17 is fonned
`by sputtering and photoetching of ITO (indium tin oxide),
`transparent conductive material. The top layer is souree
`drain wiring. A source elcctrode 18, drain e lectrode 19, and 60
`drain line 20 are formed by phmoctching a panem ofMo/AI
`laminated at a thickness of I CXXlAnoooA by sputtering, for
`example.
`The following describe a general structure of the 1FT
`subSLrllte. In the prescnt application, the full face is coated 65
`with an interlaycr insulation film 21 :such a5 SiN", then an
`oricntation control electrodc 22 is disposed so as to surround
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`Page 18 of 23
`
`25
`
`6
`the periphery of the display electrode 17. SiNx is laminated
`at a thickncu of 0.5-1 jJIll by CVD, etc. The orientation
`control electrodc 22 is formed on the interlayer insulation
`film 21 by laminating and patterning AI. Cr, Mo. etc., for
`example. As !hown in AG_ 3, the orientation control elec(cid:173)
`trode 22 is located SO as to surround the periphery of thc
`display electrode 17 and they are connected to each other
`wilh respect to thc pictUIC clement on the same row (the
`same gate line).
`Further, an orientation film 23 such as polyimide (SI Nx)
`is laminated on the full facc for vertical orientation as a
`surface orientation treatment, whereby the initial orientation
`of liquid crystal directors 4() is defined in the normal
`direction of the substrate. Rubbing treatment o f the orien(cid:173)
`tation film 23 i~ not required.
`In the invention, the TFr substrate is not limited to the
`strueture mentioned here.
`On thc other hlllld, a shielding film 31 for o pening each
`20 picture element portion and shutting off transmission oflight
`through non-display portions is formed by CT, etc., on a
`transparent substrate (opposed substrate) 30 facing thc 1FT
`substrate with a liquid CI)'stal layer 41 therebetween. The
`full face of the shielding film 3 1 is coated with ITO for
`forming a common electrOde 32. The display area of each
`picture elcment oftlle common clectrode 32 i$ etched like an
`X leuer 11$ indicated by the doned line in AG. 3 for forming
`an orientation control window 3Jg, an electrode non~xis­
`tent portion at the comroon electrode 32. Further, a vertical
`30 orientation film 34 as on the 1FT substnlle is formed on the
`full face of Ihe substrate 30 on the common electrode 32 and
`the orientation control window 33a for completing the
`opposed substrate. The common clcctrode 32 is connected to
`the TFT subslrate side by silver paste, etc., at four comers of
`thc substrate and a signal is applied from an input terminal
`installed on the TFT $ubslrate side. The orientaJion control
`eleclIode 22 connected for each row is also connected to the
`input terminal in common and the: same signal as Ihe
`common electrode is input_
`FIG. 5 is a sectional view showing the operation in the cell
`when the liquid crystal display in the cmbodiment i ~ driven.
`The orientation control e1cctrode 22 is located on both sides
`ofthc display electrode 17. They face the conunon electrode
`32 with the liquid cryst.al layer 41 therebetween. In the
`45 embodiment, the effective potential difference between the
`orientation control electrode 22 and the common electrode
`32 is set smaller than that between the display electrode 17
`and the common elcctrodc32. Therefore, in the periphery of
`the display area, an electric field 4 2 occurs from the display
`50 electrode 17 to the oommon clectrode 32 in a sl ant direction
`from within the display area to the outside of thc display
`area, thereby specifying the angle of the orientation vector
`of liquid crystal directors 40 with the electric field 42 and the
`azimuth with tbc electric field direction as an axis. That is,
`if the initial oricmation vector is at some angle wilh the
`elcetric field direction, elasticity based on a continuum
`propeny of the liquid crystal causes the orientation vector to
`change in a direction to iocrease the angle in !be shortest
`way when an electric field is applied, so that stable energy
`is provided. This effect is point symmetry in relation to four
`sides of the display electrode 17, as shown in FlG. 6. Since
`the orientation control window 33a in the common electrode
`32 contains no electrode, a weak or no electric field occurs
`around the oricntation control window 33a and thc liquid
`crystal directors 40 11ft fixed to the initial orientation state.
`TI1US., for the liquid crystal directors 40, the orientation
`vector direction is specified as point symmetry in relation to
`
`3S
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`5,608,556
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`15
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`7
`the four sides of the display area by the effect of the
`orientation control electrode 22 and the boundaries between
`areas different in orientation vector are fixed by the orien(cid:173)
`tation conuol window 33a, Because of the continuum prop(cid:173)
`en), of liquid crystals. orientation vectors can be restricted
`symmetrically at all picture elements and uniformly in their
`respective lones. The picture element display section is
`divided into four zoncs separated by the orientation contrOl
`window 33a, U, D. L. and R. For example, in visual
`recognition from the upper direction of the screen, average 10
`transmitted light in zones U and D and composite light in
`zones L and R are recognized as 1raJ1smiltcd light ncar the
`condition of visual recognition from the front. With respect
`to other directions, likewise, transmitted light equivalent to
`that on the front is recognized, reducing viewing angle
`dependency for providing a wide viewing angle.
`FIG. 7 is a plan view showing a light transmission state
`when the liquid crystal display in the embodiment is driven.
`Openings 101 arc arranged like a malrix in a black area 100
`provided by the shielding film. Display is made as macro(cid:173)
`scopic composition of transmitted light corresponding to 20
`graduations controlled in the openings 101. Each opening
`101 provides a picture element shown in FIG. 6 and the
`boundaries 102 definerl by the orientation control windows
`which have the same form in all openings 101 are repre(cid:173)
`scnted in black, but variations from onc picture element tu 25
`another do not exist, SO lhat the display is nol advcrsely
`affected.
`Thus, according to the invention, the vicwing angle
`characteristic
`in horizontal and vcrtical directions
`is
`improved for enabling display at wide vicwing angles and
`disclination Variations from one picture element to another
`arc suppressed for improving display quality_ The function
`and effect described above arc the same if thc polarity of the
`applied voltage is inverted.
`To drive the liquid crystal display in the embodiment, the
`orientation control electrode 22 is electrically connected 10
`the common electrodes 32, thereby eliminating the nced for
`the drivercireuit for the orientation control electrode 22. The
`orientation control electrodc 22 is set to lhe same potential
`as the common electrode 32, thereby leveling the potential
`difference betwecn both the electrodes 22 and 32. Therefore,
`the IX>tenlia! difference betwecn both the electrodes 22 and
`32 becomes smaller than that between the display electrode
`17 and the common electrode 32, and electric field distri(cid:173)
`bution in the cell becomes as shown in FIG. 5.
`If the orientation control electrode 22 is located near the
`display e1cctrode 17, thc control function or effect of orien(cid:173)
`tation vectors increases. Thus, the orientation control elec(cid:173)
`trode 22 preferably abuts 00 the surrouod of the display ~o
`electrode 17 as a plane or is partially superposed on the
`display elcctrode 17.
`Particularly in the invention, :as shown in FIG. 3, the
`orientation control electrode 22 is partially superimposed on
`the display elcctrode 17 for causing the superimposed por(cid:173)
`tion to serve as substorage capacitance.
`Since the structure shields transmitted light in the periph(cid:173)
`ery of the display clectrode 17, the affixing margin hetween
`thc substratcs can be madc small and the opening perccntage
`of the shielding film 32 on the opposed substrate side can be 60
`improvcd. The margin can be set based on the OUlcr periph(cid:173)
`er