Petitioner Bluehouse Global Ltd.
`Petitioner Bluehouse Global Ltd.
`
`Ex. 1005
`Ex. 1005
`
`

`

`US008169558B2
`
`(12) United States Patent
`Morimoto et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 8,169,558 B2
`May 1, 2012
`
`(54) LIQUID CRYSTAL DISPLAY DEVICE
`
`(56)
`
`References Cited
`
`(75) Inventors: Masateru Morimoto, Mobara (JP);
`Junji Tanno, Chiba (JP)
`(73) Assignees: Hitachi Displays, Ltd., Chiba (JP);
`Panasonic Liquid Crystal Display Co.,
`Ltd., Hyogo-ken (JP)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 482 days.
`
`(*) Notice:
`
`(21) Appl. No.: 12/495,899
`
`y x- - -
`
`9
`
`(22) Filed:
`
`Jul. 1, 2009
`
`(65)
`
`(30)
`
`O
`O
`Prior Publication Data
`US 201O/OOO2162 A1
`Jan. 7, 2010
`
`Foreign Application Priority Data
`
`Jul. 1, 2008 (JP)
`
`2008-172426
`
`- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
`
`2006.O1
`(51) E;MI343
`(
`.01)
`(52) U.S. Cl. ............................. 349/38; 349/39; 34.9/139
`(58) Field of Classification Search .................... 349/38,
`349/39, 139
`See application file for complete search history.
`
`U.S. PATENT DOCUMENTS
`6,747,712 B2 * 6/2004 Noh et al. ....................... 349,39
`FOREIGN PATENT DOCUMENTS
`E.
`2.83,
`"E.
`JP
`2007-017619
`1, 2007
`k .
`cited by examiner
`Primary Examiner — David Nelms
`Assistant Examiner — David Chung
`(74) Attorney, Agent, or Firm — Antonelli, Terry, Stout &
`Kraus, LLP.
`ABSTRACT
`(57)
`A liquid crystal display device includes pixels A and pixels B,
`wherein a width BB of the pixel B is smaller thana width AA
`of the pixel A. A pixel electrode formed in the pixel B is
`smaller thanapixel electrode formed in the pixel Ainarea and
`hence, capacitance formed between the pixel electrode and a
`counter electrode which is formed below the pixel electrode
`with an insulation film sandwiched therebetween becomes
`
`Small. To eliminate this difference in capacitance, a first
`
`branch electrode and a second branch electrode are formed on
`the pixel electrode of the pixel B thus increasing capacitance
`between the pixel electrode and the counter electrode. Due to
`such a constitution, it is possible to prevent the deterioration
`of image quality attributed to imbalance of capacitance.
`6 Claims, 4 Drawing Sheets
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`U.S. Patent
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`May 1, 2012
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`Sheet 1 of 4
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`US 8,169,558 B2
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`U.S. Patent
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`May 1, 2012
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`Sheet 2 of 4
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`US 8,169,558 B2
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`BLUEHOUSE EXHIBIT 1005
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`U.S. Patent
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`May 1, 2012
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`Sheet 4 of 4
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`US 8,169,558 B2
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`BLUEHOUSE EXHIBIT 1005
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`US 8,169,558 B2
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`1.
`LIQUID CRYSTAL DISPLAY DEVICE
`
`CROSS REFERENCE TO RELATED
`APPLICATION
`
`The present application claims priority from Japanese
`application.JP 2008-172426 filed on Jul. 1, 2008, the content
`of which is hereby incorporated by reference into this appli
`cation.
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`The present invention relates to a display device, and more
`particularly to a liquid crystal display device which can pre
`vent the occurrence offlickers or the like due to imbalance of
`capacitance when a size of a pixel is changed for every color
`Such that the whole screen acquires predetermined chroma
`ticity.
`2. Description of the Related Art
`A liquid crystal display device includes a TFT substrate on
`which pixel electrodes, thin film transistors (TFT) and the like
`are formed in a matrix array, a counter Substrate which is
`arranged to face the TFT Substrate in an opposed manner and
`forms color filters or the like thereon at positions correspond
`ing to the pixel electrodes of the TFT substrate, and liquid
`crystal which is sandwiched between the TFT substrate and
`the counter Substrate. Here, an image is formed by controlling
`transmissivity of light of the pixel for every pixel by changing
`the behavior of the liquid crystal molecules.
`In general, the liquid crystal display device is formed of
`pixels of respective colors consisting of red, green and blue,
`and the respective pixels have the same size. However,
`depending on a usage of the liquid crystal display device,
`there may be a case where the whole screen is requested to
`have particular hue. Alternatively, when the sizes of the pixels
`of red, green and blue are set equal, there may be a case that
`complete white cannot be obtained in white display, and color
`of the screen is deviated to particular hue. In Such a case, the
`correction of hue is required. For this end, there has been
`proposed a technique which makes a size of a pixel of red,
`green or blue different from pixels of other colors.
`JP-A-2007-17619 (patent document 1) describes the con
`stitution of an IPS (In Plane Switching) type liquid crystal
`display device in which transmissivity of a pixel of red, green
`or blue is changed for adjusting a color tone of a screen.
`JP-A-2000-162627 (patent document 2) describes the con
`stitution of a liquid crystal display device where a size of a
`blue pixel is set larger than a size of a red pixel or a green
`pixel, and to cope with a drawback caused by a change of
`capacitance for every pixel when the number of electrodes of
`blue pixels is increased, a rate between a gate/source capaci
`tance (parasitic capacitance) and the whole capacitance of a
`TFT is set to a constant value.
`JP-A-7-325287 (patent document 3) discloses the consti
`tution of a liquid crystal display device which changes aux
`iliary capacitance for preventing an image from being influ
`enced by a change of capacitance when a layer thickness of
`liquid crystal differs depending on a location.
`
`SUMMARY OF THE INVENTION
`
`When sizes of pixel electrodes are changed for bringing a
`screen into predetermined chromaticity, capacitances rel
`evant to the sizes of the pixel electrodes are also changed.
`Assuming the total capacitance relevant to an image display
`as Ct, the total capacitance Ct is expressed by Ct=Clc+Cstg+
`
`2
`Cgs. Here, Clc is capacitance generated by a liquid crystal
`layer, Cstg is capacitance (storage capacitance) generated
`between a counter electrode (or capacitive electrode) and the
`pixel electrode, and Cgs is capacitance generated between a
`gate electrode and a source electrode of a TFT.
`The above-mentioned capacitances are particularly rel
`evant to a voltage shift in which a potential of the pixel
`electrode is changed in response to an ON state or OFF state
`of the gate voltage. When the size of the pixel is changed for
`every color, the above-mentioned Ct is changed so that the
`Voltage shift is changed for every color leading to the genera
`tion of flickers or the like. With respect to such a change of
`capacitance, Cstg is particularly largely influenced.
`The task of the invention lies in the realization of the
`constitution which prevents the occurrence of drawbacks
`Such as flickers even when sizes of pixels are changed for
`every pixel for bringing an image into predetermined chro
`maticity.
`The invention has been made to overcome the above-men
`tioned drawbacks, and it is an object of the invention to
`provide a liquid crystal display device which can prevent the
`occurrence of drawbacks such as flickers by holding Cstg
`which exerts particularly large influence on image quality at
`an equal value among the pixels when sizes of pixels are
`changed for respective colors for adjusting chromaticity. To
`describe the specific constitutions of the liquid crystal display
`device, they are as follows.
`(1) According to one aspect of the invention, there is pro
`vided a liquid crystal display device which includes a first
`Substrate on which pixels are formed in regions Surrounded
`by Scanning lines which extend in the first direction and are
`arranged parallel to each other in the second direction and
`Video signal lines which extend in the second direction and
`are arranged parallel to each other in the first direction, the
`pixels being constituted of two kinds of pixels consisting of
`first pixels having a first area and second pixels having a
`Smaller area than the first pixels, a second Substrate which
`faces the first Substrate in an opposed manner and forms color
`filters and light blocking films thereon, and a liquid crystal
`layer which is sandwiched between the first substrate and the
`second Substrate, wherein in the first pixel, first capacitance is
`generated by a first electrode having a slit, an insulation film,
`and a planar second electrode which is formed below the first
`electrode with the insulation film sandwiched therebetween,
`in the second pixel, second capacitance is generated by a first
`electrode having a slit, a branch electrode branched from the
`first electrode, an insulation film, and a planar second elec
`trode which is formed below the first electrode with the insu
`lation film sandwiched therebetween, the branch electrode is
`formed in a state that the branch electrode gets over the video
`signal line and extends over the neighboring pixel, and an
`amount of the second capacitance falls within a range of 90%
`to 110% of an amount of the first capacitance.
`(2) In the liquid crystal display device having the above
`mentioned constitution (1), the direction that the branch elec
`trode extends falls within a range of 0 degree to 45 degrees in
`the liquid crystal rotational direction when the Voltage is
`applied to the pixel with respect to the direction orthogonal to
`the liquid crystal initial alignment direction on the first Sub
`Strate.
`(3) In the liquid crystal display device having the above
`mentioned constitution (1), the branch electrode is covered
`with the light blocking film formed on the second substrate.
`(4) In the liquid crystal display device having the above
`mentioned constitution (1), in the second pixel, a second
`branch electrode is further branched from the first electrode
`having a slit, and the second capacitance is generated by the
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`first electrode having a slit, the branch electrode, the second
`branch electrode, the insulation film, and the second elec
`trode.
`(5) In the liquid crystal display device having the above
`mentioned constitution (4), the second branch electrode is
`formed in a state that the second branch electrode gets over
`the video signal line and extends over the neighboring pixel.
`(6) According to another aspect of the invention, there is
`provided a liquid crystal display device which includes a first
`Substrate on which pixels are formed in regions Surrounded
`by Scanning lines which extend in the first direction and
`arranged parallel to each other in the second direction and
`Video signal lines which extend in the second direction and
`are arranged parallel to each other in the first direction, the
`pixels being constituted of two kinds of pixels consisting of
`first pixels having a first area and second pixels having a
`Smaller area than the first pixels, a second Substrate which
`faces the first Substrate in an opposed manner and forms color
`filters, a light blocking film and counter electrodes thereon,
`and a liquid crystal layer which is sandwiched between the
`first substrate and the second substrate, wherein in the first
`pixel, first capacitance is generated by a pixel electrode, an
`insulation film, and a capacitive electrode which is formed
`below the pixel electrode with the insulation film sandwiched
`therebetween, in the second pixel, second capacitance is gen
`erated by a pixel electrode, an insulation film, and a capacitive
`electrode which is formed below the pixel electrode with the
`insulation film sandwiched therebetween, a portion of the
`pixel electrode of the second pixel is formed in a state that the
`portion of the pixel electrode gets over the video signal line
`and extends over the neighboring pixel, and an amount of the
`second capacitance falls within a range of 90% to 110% of an
`amount of the first capacitance.
`According to the invention, in a method of adjusting chro
`maticity of an image by making areas of pixels different from
`each other, among the pixel shaving different areas, Storage
`capacitances generated in the respective pixels are set con
`stant. Alternatively, by setting the storage capacitances to
`values which fall within a predetermined range, it is possible
`to alleviate drawbacks such as a voltage shift or the like
`attributed to the difference in pixel area.
`
`BRIEF EXPLANATION OF DRAWINGS
`
`FIG. 1 is a cross-sectional view of a liquid crystal display
`device according to an embodiment 1 of the invention;
`FIG. 2 is a plan view of the pixel constitution according to
`the embodiment 1;
`FIG.3 is a plan view showing a part of a pixel portion in the
`pixel constitution in detail; and
`FIG. 4 is a cross-sectional view of a liquid crystal display
`device of an embodiment 2.
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`DETAILED DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`55
`
`The invention will be described in detail in conjunction
`with embodiments hereinafter.
`Embodiment 1
`A viewing angle characteristic is critically important in a
`liquid crystal display device. An IPS-type liquid crystal dis
`play device is configured to control light which passes
`through a liquid crystal layer by rotating liquid crystal mol
`ecules using a lateral electric field thus exhibiting an excellent
`viewing angle characteristic. Although there exist various
`kinds of IPS-type liquid crystal display devices, in this
`embodiment, the explanation is made with respect to a case in
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`which the invention is applied to an IPS liquid crystal display
`device where one electrode is formed of a comb-teeth-shaped
`transparent electrode and another electrode is formed of a
`matted (planar) transparent electrode.
`FIG. 1 is across-sectional view of the IPS liquid crystal
`display device to which the invention is applied. In FIG. 1,
`gate electrodes 101 are formed on a TFT substrate 100 made
`of glass. The gate electrodes 101 are formed on the same layer
`as scanning lines 500. The gate electrodes 101 are formed by
`stacking an MoCr alloy on an AlNd alloy.
`A gate insulation film 102 made of SiN is formed in a state
`that the gate insulation film 102 covers the gate electrodes
`101. Semiconductor layers 103 formed of an a-Si film are
`formed on the gate insulation film 102 at positions where the
`semiconductor layers 103 face the gate electrodes 101 in an
`opposed manner. The a-Si film is formed by a plasma CVD
`method. The a-Si film constitutes a channel portion of a TFT
`(thin film transistor), and a source electrode 104 and a drain
`electrode 105 are formed on the a-Si film with the channel
`portion in a state that the a-Si film is sandwiched between the
`gate electrode 101 and the source electrode 104 and the drain
`electrode 105. Here, an n+Silayer not shown in the drawing
`is formed between the a-Si film and the source electrode 104
`orbetween the a-Si film and the drain electrode 105. The n+Si
`layer is provided for forming an ohmic contact between the
`semiconductor layer 103 and the source electrode 104 or
`between the semiconductor layer 103 and the drain electrode
`105.
`A video signal line 600 also functions as the source elec
`trode 104, and the drain electrode 105 is connected to a pixel
`electrode 110. Both the source electrodes 104 and the drain
`electrodes 105 are formed on the same layer simultaneously.
`In this embodiment, the source electrodes 104 or the drain
`electrodes 105 are made of MoCr alloy. To decrease electric
`resistance of the source electrode 104 or the drain electrode
`105, for example, the electrode structure in which an AlNd
`alloy layer is sandwiched between MoCr alloy layers is
`adopted.
`The TFTs are covered with an inorganic passivation film
`(insulation film) 106 made of SiN. The inorganic passivation
`film 106 is provided for protecting the TFTs, and more par
`ticularly the channel portions of the TFTs from impurities. An
`organic passivation film (insulation film) 107 is formed on the
`inorganic passivation film 106. The organic passivation film
`107 also plays a role of leveling surfaces of the TFTs as well
`as a role of protecting the TFTs and hence, the organic pas
`sivation film 107 is formed with a large thickness. The thick
`ness of the organic passivation film 107 is set to a value which
`falls within a range from 1 um to 4 Lum.
`A photosensitive acrylic resin, a silicon resin, a polyimide
`resin or the like is used for forming the organic passivation
`film 107. It is necessary to form a through hole in the organic
`passivation film 107 at a portion where the pixel electrode 110
`and the drain electrode 105 are connected with each other.
`However, since the organic passivation film 107 is a photo
`sensitive film, the through hole can be formed by exposing
`and developing the organic passivation film 107 perse with
`out using photoresist.
`A counter electrode 108 is formed on the organic passiva
`tion film 107. The counter electrode 108 is formed by forming
`a transparent conductive film made of ITO (Indium Tin
`Oxide) on the whole display region by sputtering. That is, the
`counter electrode 108 is formed into a planar shape. After
`forming the counter electrode 108 on the whole surface of the
`display region by sputtering, only the counter electrode 108 at
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`a position where the through hole for electrically connecting
`the pixel electrode 110 and the drain electrode 105 is formed
`is removed by etching.
`An upper insulation film 109 made of SiN is formed in a
`state that the upper insulation film 109 covers the counter
`electrode 108. After forming the upper insulation film 109,
`through holes are formed in the upper insulation film 109 by
`etching. The through holes 111 are formed by etching the
`inorganic passivation film 106 using the upper insulation film
`109 as a resist. Thereafter, an ITO film from which pixel
`electrodes 110 are formed is formed by sputtering in a state
`that the ITO film covers the upper insulation film 109 and the
`through hole 111. The pixel electrodes 110 are formed by
`patterning the ITO film which is formed by sputtering. The
`ITO film from which the pixel electrodes 110 are formed also
`covers the through holes 111. In the through hole 111, the
`drain electrode 105 which extends from the TFT and the pixel
`electrode 110 are electrically connected with each other, and
`video signals are supplied to the pixel electrode 110 via the
`through hole 111.
`The pixel electrode 110 is formed of comb-teeth-shaped
`electrodes. A slit 112 is formed between neighboring comb
`tooth-shaped electrodes. A reference Voltage is applied to the
`counter electrode 108, and a video signal Voltage is applied to
`the pixel electrode 110. When the voltage is applied to the
`pixel electrode 110, as shown in FIG.1, lines of electric force
`are generated so that liquid crystal molecules 301 are rotated
`in the direction of the lines of electric force thus controlling
`the transmission of light radiated from a backlight 700. The
`transmission of light radiated from the backlight 700 is con
`trolled for every pixel so as to form an image on a screen.
`Here, an alignment film 113 for aligning the liquid crystal
`molecules 301 is formed on the pixel electrodes 110.
`In FIG. 1, a storage capacitance Cstg is generated between
`the planar counter electrode 108 and the comb-teeth-shaped
`pixel electrode 110. The storage capacitance Cstghas a func
`tion of alleviating a so-called Voltage shift in which apotential
`of the pixel electrode 110 is influenced when a gate voltage is
`turned on or off. Changing of a size of the pixel is equal to
`changing of a size of the pixel electrode 110 and hence, when
`40
`a size of the pixel is changed, the storage capacitance Cstg is
`also changed along with the change of the size of the pixel.
`Accordingly, a value of the Voltage shift is changed for every
`pixel. To prevent such a change, according to the invention, as
`shown in FIG. 2, branch electrodes are provided to the pixel
`electrode 110 having a narrow width so as to set a value of the
`storage capacitance Cstg of the pixel electrode 110 having a
`narrow width substantially equal to values of storage capaci
`tances of other pixels.
`In the example shown in FIG. 1, the counter electrode 108
`having a planar shape is arranged on the organic passivation
`film 107, and the comb-teeth-shaped pixel electrode 110 is
`arranged on the upper insulation film 109. On the other hand,
`the pixel electrode 110 having a planar shape may bearranged
`on the organic passivation film 107, and the comb-teeth
`shaped counter electrode 108 may be arranged on the upper
`insulation film 109. In the explanation made hereinafter, how
`ever, it is assumed that an upper comb-teeth-shaped electrode
`is the pixel electrode 110, and a lower planar matted electrode
`is the counter electrode 108.
`In FIG. 1, a counter substrate 200 is arranged on the TFT
`substrate 100 with a liquid crystal layer 300 sandwiched
`therebetween. Color filters 201 are formed on an inner side of
`the counter substrate 200. The color filters of red, green, blue
`201 are formed for every pixel thus forming a color image. A
`65
`light blocking film 202 is formed between the color filters 201
`thus enhancing a contrast of the image. Here, the light block
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`ing film 202 also plays a role of a light blocking film 202 for
`shielding the TFT from light thus preventing an optical cur
`rent from flowing into the TFT.
`An overcoat film 203 is formed in a state that the overcoat
`film 203 covers the color filters 201 and the light blocking
`films 202. The color filters 201 and the light blocking films
`202 have an uneven surface respectively and hence, the
`respective surfaces are leveled by the overcoat film 203. An
`alignment film 113 which decides an initial alignment of
`liquid crystal is formed on the overcoat film 203. In FIG. 1,
`the liquid crystal display device is an IPS liquid crystal dis
`play device and hence, the counter electrode 108 is formed on
`a TFT-substrate-100 side and is not formed on a counter
`substrate-200 side.
`As shown in FIG.1, in the IPS liquid crystal display device,
`a conductive film is not formed on an inner side of the counter
`substrate 200 side. Accordingly, a potential of the counter
`substrate 200 becomes unstable. Further, electromagnetic
`noises enter the liquid crystal layer 300 from the outside and
`hence, an image is influenced by the noises. To eliminate Such
`drawbacks, a surface conductive film 210 is formed on an
`outer side of the counter substrate 200. The surface conduc
`tive film 210 is an ITO film which is a transparent conductive
`film and is formed by Sputtering.
`As shown in FIG. 1, the constitution where liquid crystal is
`sandwiched between the TFT substrate 100 on which the
`pixel electrodes 110, the TFTs and the like are formed in a
`matrix array and the counter substrate 200 on which the color
`filters 201 and the like are formed is called a liquid crystal
`display panel. In FIG. 1, a backlight 700 is arranged on a back
`surface of the TFT substrate 100. Further, although not shown
`in the drawing, a polarizer is arranged on the back surface of
`the TFT substrate 100 and a front surface of the counter
`substrate 200 respectively. A phase difference plate maybe
`also arranged on the respective surfaces when necessary.
`FIG. 2 is a plan view showing the liquid crystal display
`device of the embodiment 1. In FIG. 2, the scanning lines 500
`extend in the lateral direction and are arranged parallel to each
`other in the longitudinal direction. Further, the video signal
`lines 600 extend in the longitudinal direction and are arranged
`parallel to each other in the lateral direction. Regions sur
`rounded by the scanning lines 500 and the video signal lines
`600 constitute the pixels.
`In FIG. 2, the pixels are constituted of pixels A each of
`which has a normal size and pixels Beach of which is smaller
`than the size of the pixel A having the normal size. The pixel
`A has a width AA and the pixel B has a width BB. The
`arrangement shown in FIG. 2 may be considered such that
`four pixels form one set or a pair of pixels consisting of pixels
`which differ in size is arranged at particular pitches.
`In FIG. 2, both of the pixel electrode 110 of the normal
`pixel A and the pixel electrode 110 of the small pixel B are
`formed of a comb-teeth-shaped electrode having a closed
`distal end. However, the pixel electrode 110 of the pixel A has
`five comb teeth portions, while the pixel electrode 110 of the
`pixel B has four comb teeth portions. The counter electrode
`108 not shown in the drawing which is formed in a planar
`matted manner is formed below the pixel electrodes 110 by
`way of the upper insulation film 109. The storage capacitance
`Cstg is generated between the pixel electrode 110 and the
`counter electrode 108.
`A size of the pixel electrode 110 of the pixel B is smaller
`than a size of the pixel electrode 110 of the pixel A and hence,
`an amount of storage capacitance Cstg of the pixel B also
`becomes Smaller than an amount of storage capacitance Cstg
`of the pixel A. Accordingly, a voltage shift differs between
`these pixels thus causing flickers or the like.
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`To eliminate the imbalance of the storage capacitance Cstg
`between the pixels, two branch electrodes consisting of a first
`branch electrode 1101 and a second branch electrode are
`provided to the pixel B thus making the storage capacitance
`Cstg of the pixel B Substantially equal to the storage capaci
`tance Cstg of the pixel A. In the pixel B shown in FIG. 2, the
`first branch electrode 1101 is formed on a left upper portion of
`the pixel B, and the second branch electrode is formed on a
`right lower portion of the pixel B. That is, an area of the pixel
`electrode 110 with which the pixel electrode 110 faces the
`counter electrode 108 is increased by an amount correspond
`ing to the branch electrodes and hence, the storage capaci
`tance Cstg can be increased.
`Assuming an amount of the storage capacitance Cstg of the
`pixel B as BCstg and an amount of the storage capacitance
`Cstg of the pixel A as ACstg, it is preferable to set the storage
`capacitance
`BCstg
`within
`a
`range
`of
`0.9ACstgsBCstgs 1.1ACstg by providing the first branch
`electrode 1101 and the second branch electrode 1102 to the
`pixel B.
`In this embodiment, as shown in FIG. 2, the first branch
`electrode 1101 and the second branch electrode 1102 get over
`the video signal line 600 and extend over the neighboring
`pixel. Due to such a constitution, it is possible to ensure a
`necessary amount of storage capacitance Cstg. Here, in some
`cases, only either one of the first branch electrode 1101 and
`the second branch electrode 1102 may be configured to
`extend over the neighboring pixel. In this case, an extending
`portion of the electrode is covered with the light blocking film
`202 on the counter substrate 200 and hence, the formation of
`an image is not influenced by the extending portion of the
`electrode. Further, the number of branch electrodes is not
`limited to two per one pixel as in the case of this embodiment.
`That is, the number of branch electrodes may be only one, or
`three or more per one pixel.
`In FIG. 2, the TFT is formed between the video signal line
`600 and the pixel electrode 110. In FIG. 2, the gate electrode
`101 of the TFT is formed of a portion branched from the
`scanning line 500. The semiconductor layer 103 is formed so
`as to cover the gate electrode 101. The video signal line 600
`also functions as the source electrode 104 of the TFT. The
`drain electrode 105 is formed below the pixel electrode 110 in
`an overlapping manner. A channel portion 1031 is formed
`between the source electrode 104 and the drain electrode 105.
`The drain electrode 105 and the pixel electrode 110 are elec
`trically connected with each other via the through hole 111.
`In FIG. 2, an arrow AL indicates the rubbing direction
`which determines the initial alignment direction of liquid
`crystal. The liquid crystal molecules 301 are aligned along the
`rubbing direction AL. When a voltage is applied between the
`pixel electrode 110 and the counter electrode 108, the liquid
`crystal molecules 301 are rotated as indicated by an arrow.
`FIG. 2 shows a case in which the rotational direction of liquid
`crystal when the Voltage is applied to the pixel is the clock
`wise direction.
`The first branch electrode 1101 and the second branch
`electrode 1102 in the pixel B are covered with the light block
`ing film 202 which is formed on the counter substrate 200 and
`hence, an image is not influenced by the formation of the first
`branch electrode 1101 and the second branch electrode 1102.
`However, to prevent an image from being influenced by a
`domain generated when a person touches the counter Sub
`strate 200, it is necessary to define an angle of the first branch
`electrode 1101 and an angle of the second branch electrode
`1102 with respect to the rubbing direction AL.
`FIG.3 is a view for explaining the relationship between the
`angle of the branch electrode and the rubbing direction AL by
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`taking the first branch electrode 1101 in the pixel B as an
`example. In FIG. 3, the first branch electrode 1101 is
`branched from the pixel electrode 110 in the pixel B in the
`leftward and upward direction. An arrow AL in FIG. 3 indi
`cates the rubbing direction. 0 is an angle made by the extend
`ing direction of the first branch electrode 1101 and the direc
`tion orthogonal to the rubbing direction (initial alignment
`direction of liquid crystal) AL. By setting 0 in FIG. 3 to a
`value which falls within a range from 0 degree to 45 degrees
`in the liquid crystal rotational direction (clockwise direction
`in this embodiment) when a Voltage is applied to the pixel, it
`is possible to prevent the generation of domain. Since the
`liquid crystal rotational direction is determined based on the
`initial alignment direction of liquid crystal, the extending
`direction of comb teeth of the pixel electrode 110 or a kind of
`liquid crystal (positive or negative), there may be a case that
`liquid crystal rotational direction is set in the counterclock
`wise direction.
`Although FIG. 3 explains the first branch electrode 1101,
`the same goes for the second branch electrode 1102 formed
`on a right lower portion of the pixel B. That is, the extending
`direction of the first branch electrode 1101 and the second
`branch electrode 1102 are parallel to each other except for the
`difference that the first branch electrode 1101 is formed on the
`left upper portion of the pixel B and the second branch elec
`trode 1102 is formed on the right lower portion of the pixel B
`and hence, a technique used for setting the extending direc
`tion of the first branch electrode 1101 is directly applicable to
`setting of the extending direction of the second branch elec
`trode 1102.
`AS has been explained above, according to this embodi
`ment, in setting chromaticity of an image by changing areas
`of pixels, chromaticity of the image can be set without chang
`ing a value of Cstg and hence, drawbacks such as flickers can
`be prevented. Further, according to this embodiment, the first
`branch electrode 1101 and the second branch electrode 1102
`provided for maintaining Cstgat a predetermined value are
`covered with the light blocking film 202 and hence, the
`above-mentioned setting of chromaticity of the image can be
`performed without changing transmissivity of the pixel elec
`trode 110. Further, according to this embodiment, setting of
`Cstg can be performed by merely adjusting a shape of the
`pixel electrode 110 of the pixel B having the narrow width.
`Accordingly, Cstg can be adjusted without pushing up a
`manufacturing cost.
`Embodiment 2
`This embodiment provides the constitution which can
`change chromaticity of an image by changing a size of a pixel
`of particular color from sizes of other pixels with respect to a
`TN (Twisted Nematic) liquid