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`(12) United States Patent
`US 10,423,034 B2
`(10) Patent N0.:
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` Ochiai et al. (45) Date of Patent: Sep. 24, 2019
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`US010423034B2
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`(56)
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`(52) US. C1.
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`CPC .......... G02F 1/1339 (2013.01); G02F 1/1368
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`(2013.01); G02F 1/13394 (2013.01); G02F
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`1/136277 (2013.01); G02F 1/136286
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`(2013.01); G02F [/134363 (2013.01); G02F
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`[/136227 (2013.01); G02F 2001/13415
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`(2013.01); G02F 2001/13606 (2013.01)
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`(58) Field of Classification Search
`CPC ..................................................... G02F 1/1339
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`See application file for complete search history.
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`References Cited
`U.S. PATENT DOCUMENTS
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`6,762,805 B2
`7/2004 Ishino
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`6,921,917 B2
`7/2005 Choi et al.
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`(Continued)
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`FOREIGN PATENT DOCUMENTS
`
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`11-084386
`3/1999
`JP
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`Primary Examiner 7 Edmond C Lau
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`(74) Attorney, Agent, or Firm 7 Juan Carlos A. Marquez;
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`Marquez IP Law Office, PLLC
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`ABSTRACT
`(57)
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`A column for defining the interval between a TFT substrate
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`and an opposed substrate is formed at a crossing point
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`between a drain line and a scanning line. At the crossing
`point where the column is formed, the drain line is formed
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`to have a wider width to prevent light leakage. Further, at the
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`crossing point where the column is formed, the scanning line
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`is formed to have a narrower width to prevent increase of
`capacitance between the drain line and the seaming line.
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`The column is formed at a crossing point corresponding to
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`a specific color, e.g., a blue pixel B, so that a difference in
`transmittance and in characteristic of thin film transistors
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`due to formation of the column is initially compensated.
`8 Claims, 6 Drawing Sheets
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`(72)
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`( * ) Notice:
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`(54) LIQUID CRYSTAL DISPLAY DEVICE
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`(71) Applicants:Japan Display Inc., Tokyo (JP);
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`Panasonic Liquid Crystal Display Co.,
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`Ltd., Himeji-shi, Hyogo-ken (JP)
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`Inventors: Takahiro Ochiai, Chiba (JP); Tohru
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`Sasaki, Mobara (JP); Tetsuya Nagata,
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`Mobara (JP)
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`(73) Assignees: Japan Display Inc., Tokyo (JP);
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`Panasonic Liquid Crystal Display Co.,
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`Ltd., Hyogo-ken (JP)
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`Subject to any disclaimer, the term of this
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`patent is extended or adjusted under 35
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`U.S.C. 154(b) by 0 days.
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`(21) Appl. No.: 16/019,937
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`(22)
`Jun. 27, 2018
`Filed:
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`(65)
`Prior Publication Data
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`US 2018/0307072 A1
`Oct. 25, 2018
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`Related US. Application Data
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`(63) Continuation of application No. 14/709,529, filed on
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`May 12, 2015, now Pat. No. 10,031,372, and a
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`(Continued)
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`Foreign Application Priority Data
`(30)
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`(JP) ................................. 2008-044247
`Feb. 26, 2008
`
`Int. Cl.
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`G02F 1/1339
`G02F 1/1362
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`(51)
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`(2006.01)
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`(2006.01)
`(Continued)
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`BCF
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`0H40H3
`2:32106
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`7111
`:1nn1111l1111111
`WW5‘”711.1111 71111—4”
`71/31":
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`LE“—
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`US 10,423,034 132
`Page 2
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`Related US. Application Data
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`continuation of application No. 13/600,349, filed on
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`Aug. 31, 2012, now Pat. No. 9,036,104, and a con-
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`tinuation of application No. 12/379,363, filed on Feb.
`19, 2009, now Pat. No. 8,284,339.
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`Int. Cl.
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`G02F 1/1368
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`G02F 1/1343
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`G02F 1/1341
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`G02F 1/136
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`(2006.01)
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`(2006.01)
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`(2006.01)
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`(2006.01)
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`
`References Cited
`U.S. PATENT DOCUMENTS
`
`
`6,999,060 B2
`2/2006 Choo
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`7,133,108 B2
`11/2006 Shimizu et al.
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`7,285,902 B2
`10/2007 K00 et 31.
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`7,349,038 B2
`3/2008 Park et al.
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`7,352,429 B2
`4/2008 Tseng et al.
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`2002/0044230 A1
`4/2002 Yamazaki et al.
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`2004/0084673 A1*
`5/2004 Hirakata ............. G02F 1/ 13394
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`257/59
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`2007/0002219 A1
`1/2007 Lee et al.
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`2007/0216627 A1
`9/2007 Kim et al.
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`2008/0123007 A1
`5/2008 Cui et al.
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`2008/0185589 A1
`8/2008 Shin et al.
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`2009/0284695 A1
`11/2009 Kim et al.
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`* cited by examiner
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`(51)
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`(56)
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`Page 2 of 15
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`U.S. Patent
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`Sep.24,2019
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`Sheet170f6
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`US 10,423,034 132
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`Sep. 24, 2019
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`Sheet 2 0f 6
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`US 10,423,034 B2
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`U.S. Patent
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`Sep. 24, 2019
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`Sheet 3 0f 6
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`US 10,423,034 B2
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`FlG.3
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`80F
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`00
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`VIII/I’ll
`'-'-
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`Fl- ‘
`Illnlflllllnlilj
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`101
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`CH4
`CH3
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`198
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`HO
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`m 104
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`U.S. Patent
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`Sheet 4 0f 6
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`US 10,423,034 B2
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`FIG.4
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`200
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`BM Mil/I'll
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`112
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`GO?
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`Sheet 6 0f 6
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`US 10,423,034 B2
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`FIG.6
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`200
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`LIQUID CRYSTAL DISPLAY DEVICE
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`CROSS-REFERENCE TO RELATED
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`APPLICATION
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`This application is a Continuation of US. application Ser.
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`No. 14/709,629 filed May 12, 2015, which is a Continuation
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`of US. application Ser. No. 13/600,349 filed Aug. 31, 2012,
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`which is a Continuation of US. application Ser. No. 12/379,
`10
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`363 filed on Feb. 19, 2009. The present application claims
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`priority from US. application Ser. No. 13/600,349 field on
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`Aug. 31, 2012, which claims priority from US. application
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`Ser. No. 12/379,363 filed on Feb. 19, 2009, which claims
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`priority from Japanese application JP2008-044247 filed on
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`Feb. 26, 2008, the content of which is hereby incorporated
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`by reference into this application.
`BACKGROUND OF THE INVENTION
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`1. Field of the Invention
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`The present invention relates to a liquid crystal display
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`device, and in particular to a technique for ensuring an
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`appropriate interval between a TFT substrate and an opposed
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`substrate, using a column-type spacer.
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`2. Description of the Related Art
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`In a liquid crystal display device, liquid crystal is filled
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`between a TFT substrate with a pixel electrode and a thin
`film transistor (TFT) formed thereon and an opposed sub-
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`strate with a color filter or the like formed thereon, and the
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`liquid crystal particles are controlled by means of an electric
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`field to thereby form an image. The interval between the
`TFT substrate and the opposed substrate is very small, such
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`as of the order of a few microns. Conventionally, the interval
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`between the TFT substrate and the opposed substrate is
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`determined by dispersing plastic beads and the like. Accord-
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`ing to this interval setting by dispersing beads, however, the
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`beads may not be dispersed consistently, and in such a case
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`the interval between the TFT substrate and the opposed
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`substrate may not be set as predetermined. In addition, the
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`beads may be dispersed on a pixel electrode, which may
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`cause a problem of light leakage in the vicinity of the beads.
`Meanwhile, conventionally, in order to fill liquid crystal,
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`the space between the TFT substrate and the opposed
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`substrate is sealed to be vacant, and liquid crystal is injected
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`into the space by utilizing atmospheric pressure. This
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`method, however, takes time to complete injection of liquid
`crystal when the interval between the TFT substrate and the
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`opposed substrate is small and the surface of the liquid
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`crystal display is large. As a result, manufacturing through-
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`put is reduced, and manufacturing cost resultantly increases.
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`In order to address the above, there has been developed a
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`technique, e.g., for applying, by dropping,
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`amount of liquid crystal onto a TFT substrate and thereafter
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`forming an opposed substrate to seal
`the liquid crystal
`in-between.
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`As described above, conventionally, the interval between
`60
`the TFT substrate and the opposed substrate is maintained by
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`small beads dispersed therein. However, according to the
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`above described liquid crystal dropping method, the dis-
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`persed beads may move as the liquid crystal is dropped,
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`which results in an area with many beads and an area with
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`only a few beads. This results in an inconsistent interval
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`between the TFT substrate and the opposed substrate, and an
`inconsistent
`interval between the TFT substrate and the
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`45
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`opposed substrate in turn results in a problem of reduced
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`image contrast and/or inconsistent pixels in a liquid crystal
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`display device.
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`In order to address the above described problem with a
`case in which the interval between a TFT substrate and an
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`opposed substrate is set utilizing beads, there is available a
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`technique for defining the interval between the TFT sub-
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`strate and the opposed substrate by forming a column on
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`either the TFT substrate or the opposed substrate, as dis-
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`closed in Japanese Patent Laid-open Publication No. Hei
`11-84386.
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`The column for defining the interval between the TFT
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`substrate and the opposed substrate is conventionally formed
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`on the opposed substrate. Specifically,
`in formation of a
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`column on the opposed substrate, the column is formed such
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`that, after the opposed substrate and the TFT substrate are
`combined to each other, the column abuts on a predeter-
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`mined position on the TFT substrate. However, should the
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`opposed substrate and the TFT substrate be displaced from
`each other when being combined to each other, a column
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`resultantly abuts outside the predetermined position on the
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`TFT substrate. This may result in a column formed on a
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`pixel electrode or a column falling on a through-hole formed
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`on a line of the TFT substrate. A column formed on a pixel
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`electrode results in light leakage due to orientation distur-
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`bance in the portion where such a column is formed. A
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`column falling on a through-hole results in an interval not
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`appropriately defined between the TFT substrate and the
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`opposed substrate.
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`Japanese Patent Laid-open Publication No. Hei 11-84386
`discloses a structure in which a column is formed on either
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`the opposed substrate or the TFT substrate in a position on
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`a capacitance line in order to address orientation disturbance
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`which would be caused in the vicinity of the column, and
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`moreover,
`the capacitance line is laid extending in the
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`rubbing direction of the alignment
`film. However,
`the
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`capacitance line, which is essential in the above described
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`structure disclosed in Japanese Patent Laid-open Publication
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`No. Hei 11-84386, reduces transmittance of the liquid crys-
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`tal display device. In particular, the capacitance line extend-
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`ing in the rubbing direction of the alignment
`film, as
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`described in Japanese Patent Laid-open Publication No. Hei
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`11-84386, further reduces the transmittance.
`SUMMARY OF THE INVENTION
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`An object of the present invention is to realize a liquid
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`crystal display device having a structure in which the
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`interval between the TFT substrate and the opposed sub-
`strate is defined by a column and oriental disturbance and
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`transmittance reduction due to formation of the column are
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`suppressed.
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`In order to attain the above described object, according to
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`one aspect of the present invention, a column for defining
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`the interval between the TFT substrate and the opposed
`substrate is formed on the TFT substrate at a crossing point
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`between a drain electrode and a scanning line. This column
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`is formed at a crossing point between a scanning line and a
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`drain line corresponding to a pixel of a specific color.
`Further, at a crossing point between a scanning line and a
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`drain line corresponding to a pixel of a specific color, the
`width of the drain line is formed wider than that in other
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`positions, while the width of the corresponding scanning
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`line is formed narrower than that in other positions.
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`According to another aspect of the present invention, at a
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`crossing point between a scanning line and a drain line
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`corresponding to a pixel of a specific color, the width of the
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`65
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`Page 9 of 15
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`Page 9 of 15
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`

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`US 10,423,034 B2
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`3
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`scanning line is formed wider than that in other positions,
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`while the width of the corresponding drain line is formed
`narrower than that in other positions. Specifically, the fol-
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`lowing arrangement is employed.
`5
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`(1) According to one aspect of the present invention, there
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`is provided a liquid crystal display device having scan-
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`ning lines extending in a lateral direction and aligned in
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`a longitudinal direction, drain lines extending in the
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`longitudinal direction and aligned in the lateral direction,
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`a TFT substrate having pixels each having a TFT and a
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`pixel electrode and formed in an area enclosed by the
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`drain line and the scanning line, the pixels constituting a
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`first pixel, a second pixel, and a third pixel, respectively,
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`depending on a color to which the respective pixel cor-
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`responds, and being aligned in the lateral direction, an
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`opposed substrate placed with a predetermined interval
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`with respect
`to the TFT substrate, and liquid crystal
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`enclosed between the TFT substrate and the opposed
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`substrate, wherein a column for defining the interval
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`between the TFT substrate and the opposed substrate is
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`formed at a crossing point between the drain line and the
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`scanning line corresponding to the first pixel, and a width
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`of the drain line is wider at the crossing point where the
`column is formed than that of the drain line in another
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`position.
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`(2) In the above described liquid crystal display, at a point
`where the width of the drain line is wider, a width of the
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`scanning line may be narrower than that of the scanning
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`line in another position.
`30
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`(3) In the above described liquid crystal display, a first TFT
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`may be formed at the crossing point between the drain line
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`and the scanning line, where the column is formed, a
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`second TFT may be formed at a position adjacent to the
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`crossing point between the drain line and the scanning
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`line, where the column is formed, the first TFT and the
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`second TFT may be electrically connected to each other,
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`and a channel length of the first TFT may be shorter than
`that of the second TFT.
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`(4) In the above described liquid crystal display, a channel
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`length of a TFT formed at a crossing point between the
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`drain line and the scanning line corresponding to the first
`pixel may be shorter than that of a TFT formed at a
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`crossing point between the drain line and the scanning
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`line corresponding to the second pixel or the third pixel.
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`(5) In the above described liquid crystal display, the liquid
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`crystal display device may be of an IPS method.
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`(6) According to another aspect of the present invention,
`there is provided a liquid crystal display device having
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`scanning lines extending in a lateral direction and aligned
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`50
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`in a longitudinal direction, drain lines extending in the
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`longitudinal direction and aligned in the lateral direction,
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`a TFT substrate having pixels each having a TFT and a
`pixel electrode and formed in an area enclosed by the
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`drain line and the scanning line, the pixels constituting a
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`first pixel, a second pixel, and a third pixel, respectively,
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`depending on a color to which the respective pixel cor-
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`responds, and being aligned in the lateral direction, an
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`opposed substrate placed with a predetermined interval
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`with respect
`to the TFT substrate, and liquid crystal
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`enclosed between the TFT substrate and the opposed
`substrate, wherein a column for defining the interval
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`between the TFT substrate and the opposed substrate is
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`formed at a crossing point between the drain line and the
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`scanning line corresponding to the first pixel, and a width
`65
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`of the scanning line is wider at the crossing point where
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`the column is formed than that of the scanning line in
`another position.
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`(7) In the above described liquid crystal display device, at a
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`point where the width of the scanning line is wider, a
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`width of the drain line may be narrower than that of the
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`drain line in another position.
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`(8) In the above described liquid crystal display device, a
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`first TFT may be formed at the crossing point between the
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`drain line and the scanning line, where the column is
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`formed, a second TFT may be formed at a position
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`adjacent to the crossing point between the drain line and
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`the scanning line, where the column is formed, the first
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`TFT and the second TFT may be electrically connected to
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`each other, and a channel length of the first TFT may be
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`longer than that of the second TFT.
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`(9) In the above described liquid crystal display device, a
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`channel
`length of a TFT formed at a crossing point
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`between the drain line and the scanning line correspond-
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`ing to the first pixel may be longer than that of a TFT
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`formed at a crossing point between the drain line and the
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`scanning line corresponding to the second pixel or the
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`third pixel.
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`(10) In the above described liquid crystal display device, the
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`liquid crystal display device may be of an IPS method.
`
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`According to the present
`invention, as a column for
`
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`
`
`defining the interval between a TFT substrate and an
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`opposed substrate is formed on the TFT substrate side at a
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`crossing point between a scanning line and a drain line,
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`problems due to formation of the column, including reduc-
`tion of transmittance and light leakage due to orientation
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`disturbance can be reduced. Further, as the width of the drain
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`line is made wider in a position where the column is formed,
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`the problem of light leakage due to orientation disturbance
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`can be further suppressed. Still further, as the width of the
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`scanning line is made narrower in a position where the width
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`of the drain line is wider, increase of parasitic capacitance
`can be suppressed.
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`invention, as the column is
`According to the present
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`formed only at a crossing point between a drain line and a
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`scanning line corresponding to a pixel of a specific color,
`difference in transmittance or characteristics of TFT’s can be
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`compensated for through initial setting, so that color incon-
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`sistency due to formation of a column can be prevented.
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`According to the present invention, as a column is formed
`
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`at a crossing point between a drain line and a scanning line
`and the width of the scanning line is made wider in a position
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`where the column is formed than that in other positions, light
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`leakage due to orientation disturbance can be reduced.
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`Further, as the width of the drain line is made narrower in a
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`position where the width of the scanning line is wider,
`increase of parasitic capacitance can be suppressed.
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`BRIEF DESCRIPTION OF THE DRAWINGS
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`FIG. 1 is a plan view of a TFT substrate according to a
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`first embodiment;
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`FIG. 2 is a plan view of an opposed substrate according
`to the first embodiment;
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`FIG. 3 is a cross sectional view along the line III-III in
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`FIG. 1;
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`FIG. 4 is a cross sectional view along the line IV—IV in
`FIG. 1;
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`FIG. 5 is a plan view of a TFT substrate according to a
`second embodiment; and
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`FIG. 6 is a cross sectional view along the line VI-VI in
`FIG. 5.
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`Page 10 of 15
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`Page 10 of 15
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`

`

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`
`US 10,423,034 B2
`
`5
`DETAILED DESCRIPTION OF THE
`
`
`INVENTION
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`In the following, embodiments of the present invention
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`will be described in detail, based on a structure of an actual
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`liquid crystal cell.
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`6
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`column 130 is formed on the TFT substrate 100, a problem
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`due to displacement in position of the column 130 when
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`combining the TFT substrate 100 and the opposed substrate
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`200 may be less serious, compared to a case in which the
`column 130 is formed on the opposed substrate 200.
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`In this embodiment, as the column 130 is formed at a
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`crossing point between the scanning line 105 and the drain
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`line 107, deterioration in transmittance can be suppressed.
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`This is because the crossing point between the scanning line
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`105 and the drain line 107 originally does not pass light
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`through, and is not utilized in image formation due to a TFT
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`present in the vicinity of the crossing point.
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`However, as formation of the column 130 may disturb
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`orientation of the liquid crystal in the vicinity of the column
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`130, in order to prevent this influence, in this embodiment,
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`the width of the drain line 107 is made wider in the vicinity
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`of the crossing point with the scanning line 105. Specifically,
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`in this embodiment, the width of the drain line 107 at the
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`crossing point is double or larger the width of the drain line
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`107 in other positions. Even this arrangement exerts only
`little influence in terms of reduction of transmittance as the
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`crossing point between the scanning line 105 and the drain
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`line 107 originally does not contribute to image formation.
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`As the width of the drain line 107 is wider at the crossing
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`point, the scanning line 105 overlaps the drain line 107 at the
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`crossing point in an increased area. This means increase of
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`parasitic capacitance, which brings, e.g., a phenomenon
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`such as increase of a shift voltage or the like when the
`concerned TFT shifts from ON to OFF or vice versa. In this
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`embodiment,
`in order to suppress increase of parasitic
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`capacitance in the vicinity of the crossing point, the width of
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`the scanning line 105 in the vicinity of the crossing point is
`made narrower.
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`In FIG. 1, a red pixel R, a blue pixel B, and a green pixel
`G are aligned in the lateral direction. As shown in FIG. 1, the
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`column 130 is formed only at a crossing point between the
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`scanning line 105 and the drain line 107 corresponding to the
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`blue pixel B. In other words, the column 130 is formed at a
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`crossing point where a TFT for controlling the blue pixel B
`is formed. As the width of the drain line 107 is wider in a
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`position where the column 130 is formed, the transmittance
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`in the position may be slightly reduced compared to that in
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`a position without the column 130 and the characteristic of
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`the concerned TFT may become different from that of other
`TFT’s.
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`Here, if the column 130 is formed spreading to pixels of
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`three colors, control for color inconsistency or the like is
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`diflicult to be properly achieved. In this embodiment, how-
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`ever, as the column 130 is formed only at a crossing point
`corresponding to the blue pixel B, influence on color incon-
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`sistency due to formation of the column 130 is prevented. In
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`this case,
`transmittance of the blue pixel B alone may
`become smaller than that of the pixels of other colors, and
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`the characteristic of a TFT which controls the blue pixel B
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`may become different from that of a pixel of another color.
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`This, however, can be addressed through initial setting for
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`compensation of the characteristic.
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`In FIG. 1, a crossing point between the scanning line 105
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`and the drain line 107 corresponding to the blue pixel B
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`appears every three pixel pitch in the lateral direction, and
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`the width of the drain line 107 is wider at all crossing points
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`corresponding to the blue pixel B than that in other posi-
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`tions. Meanwhile, it is unnecessary to form a column 130 at
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`all crossing points corresponding to the blue pixel B. This is
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`because presence of only the number of columns 130
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`necessary to ensure the interval between the TFT substrate
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`100 and the opposed substrate 200 is suflicient. In this
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`30
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`First Embodiment
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`10
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`FIG. 1 is a plan view showing a pixel portion of a TFT
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`substrate to which the present invention is applied; FIG. 2 is
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`a plan view showing an opposed substrate to be combined
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`with the TFT substrate; FIG. 3 is a cross sectional view
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`along the line III-III shown in FIG. 1; and FIG. 4 is a cross
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`sectional view along the line IV—IV shown in FIG. 1.
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`In FIG. 1, scanning lines 105 extend in the lateral direc-
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`tion and are aligned in the longitudinal direction, and drain
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`lines 107 extend in the longitudinal direction and are aligned
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`in the lateral direction. An area enclosed by the scanning line
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`105 and the drain line 107 constitutes a pixel. In FIG. 1, a
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`blue pixel B, a green pixel G, and a red pixel R are
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`sequentially aligned in the lateral direction. A liquid crystal
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`display device according to this embodiment is of a so-
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`called IPS method, and adjusts the amount of light to pass
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`through the liquid crystal by rotating the liquid crystal
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`particle 140 in a direction parallel to the substrate.
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`In FIG. 1, a comb-electrode which constitutes a pixel
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`electrode 113 is provided inside a pixel enclosed by the
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`scanning line 105 and the drain line 107, and a plane
`common electrode 111 (not shown) is provided under the
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`comb-electrode with an insulating film in-between. Th