JP4115649B2 - Active matrix liquid crystal display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an active matrix type liquid crystal display device used for a liquid crystal television, a notebook personal computer or the like.
[0002]
[Prior art]
  12 and 13 are a plan view and a cross-sectional view of a general active matrix liquid crystal display device. The active matrix liquid crystal display device is roughly constituted by a liquid crystal panel 1, a gate drive circuit 2, a source drive circuit 3 and a backlight 4.
[0003]
  Further, the liquid crystal panel 1 includes an active matrix substrate 5, a counter substrate 6, a liquid crystal layer 7 sandwiched between the substrates 5 and 6, and a deflection plate (not shown) that is in close contact with the outside of the substrates 5 and 6. Outlined.
[0004]
  The active matrix substrate 5 includes a plurality of scanning wirings (not shown) arranged in parallel, a plurality of signal wirings 9 arranged in parallel perpendicularly to the scanning wirings via an insulating film 8, A thin film transistor (TFT) 10 disposed in the vicinity of each crossing position of the scanning wiring and the signal wiring 9, a plurality of pixel electrodes 11 disposed in a region surrounded by the scanning wiring and the signal wiring 9 are formed. .
[0005]
  FIG. 14 is a plan view of one pixel portion in the active matrix substrate 5. Since the pixel electrode 11 is formed in the same layer as the signal wiring 9, the pixel electrode 11 is formed so as not to contact the signal wiring 9 while maintaining a predetermined distance. The TFT 10 is a three-terminal element, and current conduction between the drain electrode 13 and the source electrode 14 is controlled by a voltage applied to the gate electrode 12. The gate electrode 12 is connected to the adjacent scanning line 15, the source electrode 14 is connected to the adjacent signal line 9, and the drain electrode 13 is connected to the pixel electrode 11.
[0006]
  On the other hand, color filters 16 are formed on the counter substrate 6 at positions corresponding to the pixel electrodes 11 in the order of arrangement of red, green, and blue. A black matrix 17 is formed between the color filters 16 and 16 as a light shielding film that prevents light leakage from between the scanning wiring 15 and the signal wiring 9 and the pixel electrode 11. Further, a counter electrode 18 made of a transparent conductive material is formed on the upper layer. The gate drive circuit 2 and the source drive circuit 3 are connected to the terminals of the scanning wiring 15 and the signal wiring 9 arranged around the liquid crystal panel 1, respectively.
[0007]
  Next, a driving method of the active matrix liquid crystal display device having the above configuration will be described.
[0008]
  In the driving method of the active matrix liquid crystal display device, when writing the pixel array in the n-th row, an on signal (a potential at which the TFT 10 is turned on: Vgh) is applied from the gate drive circuit 2 to the scanning wiring 15n in the n-th row. Entered. At this time, an off signal (a potential at which the TFT 10 is turned off: Vgl) is input to the scan lines other than the scan line 15n. Therefore, only the TFT 10 in the nth row is turned on. In this case, a source signal having a voltage to charge the pixels (pixel electrodes 11 and the liquid crystal layer 7) in the n-th row is supplied from the source drive circuit 3 to each signal line 9.
[0009]
  Thus, when writing to the array of pixels in the n-th row is completed, an off signal is input to the scanning wiring 15n, while an on signal is input to the scanning wiring 15 (n + 1). By repeating the above operation, an arbitrary voltage value is charged in all the pixels. Since the transmittance of the liquid crystal layer 7 between the pixel electrode 11 and the counter electrode 18 changes depending on the voltage applied between the electrodes 11 and 18, the light from the backlight 4 is adjusted to display an arbitrary image. Is done.
[0010]
  Incidentally, a structure in which a pixel electrode is provided on an interlayer insulating film, the pixel electrode and the signal wiring are formed in different layers, and the pixel electrode is overlaid on the signal wiring has been proposed (Japanese Patent Laid-Open No. 63-279228). etc). FIG. 15 is a cross-sectional view of one pixel in an active matrix liquid crystal display device having a structure in which the pixel electrode is overlaid on a signal wiring. FIG. 16 is a plan view of the active matrix substrate shown in FIG. In such a configuration, the pixel electrode 21 and the signal wiring 22 are formed in different layers, and the pixel electrode 21 and the signal wiring 22 are overlapped with each other via the interlayer insulating film 23. The gap with 22 can be eliminated. Therefore, the area (aperture ratio) of the pixel electrode 21 can be enlarged, and the power consumption of the active matrix liquid crystal display device can be suppressed. Reference numeral 24 denotes an active matrix substrate, 25 denotes a TFT, 26 denotes a liquid crystal layer, 27 denotes a counter electrode, 28 denotes a counter substrate, 29 denotes a scanning wiring, 30 denotes a contact hole, 31 denotes an auxiliary capacitance electrode, and 32 denotes an auxiliary capacitance wiring. .
[0011]
  However, when the structure in which the pixel electrode 21 is overlapped on the signal wiring 22 as described above is adopted, as shown in FIG. 14, the pixel electrode 11 has a predetermined distance from the signal wiring 9 as compared with the conventional structure. The electrostatic capacitance Csd between the pixel electrode 21 and the signal wiring 22 increases. In that case, as the capacitance Csd increases, the potential of the pixel easily changes depending on the source signal, and display characteristics called shadowing deteriorate.
[0012]
  Hereinafter, this mechanism will be described using an equivalent circuit of the active matrix substrate 24 shown in FIG. That is, when the ON signal Vgh is input to the scanning wiring Gn and the TFT 23 is turned on, the voltage Vs1 of the signal wiring S1 is charged in the pixel electrode P1.
[0013]
  Next, when the off signal Vgl is input to the scanning wiring Gn and the TFT 23 is turned off, the voltage Vs1 ′ to be written to the pixel electrode P2 of the next stage is supplied to the signal wiring S1. In that case, the voltage of the pixel electrode P1 changes under the influence of the voltage Vs1 ′ of the signal wiring S1 via the capacitance Csd1. If the voltage of the pixel electrode P1 at that time is Vp1,
    Vp1 = Vs1− (Csd1 (Vs1−Vs1 ′) + Csd2 (Vs2−Vs2 ′))
                                  / (Cp + Csd1 + Csd2) (1)
It becomes. Here, Cp is the capacitance of the pixel electrode (Cp = liquid crystal capacitance Clc + auxiliary electrode capacitance Ccs), Csd1 is the capacitance between the signal line S1 and the pixel electrode P1, and Csd2 is the signal line S2 and the pixel electrode. Vs1 and Vs2 are voltages of the signal wirings S1 and S2 when the scanning wiring Gn in the n-th column is in an ON state, and Vs1 'and Vs2' are in the (n + 1) th column. This is the voltage of the signal wirings S1, S2 when the scanning wiring G (n + 1) is on.
[0014]
  In the gate line inversion driving (1H inversion driving) which is a general driving method of an active matrix liquid crystal display device, the polarity of the source signal is inverted for each gate line. Here, if the gradations of adjacent neighbors are the same,
        Vs = Vs1 = Vs2, Vs ′ = Vs1 ′ = Vs2 ′ (2)
Therefore, from the formula (1) and the formula (2),
  Vp1 = Vs- (Csd1 + Csd2) / (Cp + Csd1 + Csd2). (Vs-Vs') (3)
It becomes. Thus, in 1H inversion driving, the amount of change in pixel potential is proportional to (Csd1 + Csd2). For this reason, shadowing appears conspicuously as the capacitance Csd between the signal line S and the pixel electrode P increases.
[0015]
  On the other hand, dot inversion driving has been proposed as a driving method for suppressing a change in pixel potential due to the capacitance Csd between the signal wiring S and the pixel electrode P. In this dot inversion drive, the polarity of the source signal is inverted for each gate line, and a signal having a reverse polarity is input for each source line on the source side.
[0016]
  In the case of the dot inversion driving, assuming that the adjacent gradations are the same,
        Vs = Vs1 = −Vs2, Vs ′ = Vs1 ′ = − Vs2 ′ (4)
Therefore, from the equations (1) and (4),
  Vp1 = Vs- (Csd1-Csd2) / (Cp + Csd1 + Csd2). (Vs-Vs') (5)
It becomes. Thus, in dot inversion driving, the amount of change in pixel potential is proportional to the difference between the capacitance Csd1 and the capacitance Csd2. Therefore, the shadowing phenomenon can be significantly suppressed as compared with the case of 1H inversion driving, and the image quality of the liquid crystal display device can be improved. In particular, if the difference between the capacitance Csd1 and the capacitance Csd2 regarding the pixels adjacent in the extending direction of the scanning wiring 29 is reduced, the shadowing phenomenon can be greatly suppressed.
[0017]
[Problems to be solved by the invention]
  However, the conventional active matrix liquid crystal display device shown in FIGS. 15 and 16 has the following problems. That is, as described above, the dot inversion driving is employed in the active matrix liquid crystal display device having the structure in which the pixel electrode 21 and the signal wiring 22 are overlapped via the interlayer insulating film 23 as shown in FIGS. As a result, the aperture ratio can be increased and the shadowing phenomenon caused by the coupling capacitance Csd between the signal line 22 and the pixel electrode 21 can be suppressed.
[0018]
  However, on that side, the following new problems arise. In a general liquid crystal display device, since the photolithography process is performed in units of blocks, misalignment between the blocks occurs. As a result, the overlapping width between the signal line S and the pixel electrode P changes, and the capacitance Csd therebetween changes. When the dot inversion driving is adopted, the pixel potential is easily changed due to the change of the capacitance Csd, so that the transmittance is changed in units of blocks.
[0019]
  For example, as shown in FIG. 18, a case where an alignment deviation dx occurs in the photolithography process of the pixel electrode P is considered. In this case, since the amount of overlap of the pixel electrode P with the signal wiring S1 increases, the capacitance Csd1 between the signal wiring S1 and the pixel electrode P increases, and conversely, the electrostatic capacitance Csd2 between the signal wiring S2 and the pixel electrode P. Decrease. FIG. 19 shows the relationship between the misalignment dx and the capacitance Csd1 or the capacitance Csd2 in the photolithography process. As shown in FIG. 19, as the misalignment dx increases, the difference between the capacitance Csd1 and the capacitance Csd2 increases, and the amount of change in pixel potential increases.
[0020]
  In a general photolithography process, exposure is performed by dividing the surface of the active matrix substrate into several blocks. For this reason, when the misalignment occurs, the overlap width between the signal wiring and the pixel electrode changes between the blocks, and as a result, a transmittance difference occurs between the blocks of the active matrix liquid crystal display device. FIG. 20 shows the relationship between the alignment deviation dx and the transmittance difference ΔT with respect to a block having no alignment deviation with respect to the block in which the alignment deviation occurs.
[0021]
  That is, when the active matrix type liquid crystal display device having a structure in which the pixel electrode is overlaid on the signal wiring is driven by dot inversion, the change amount of the pixel potential due to the coupling capacitance Csd itself is reduced. The variation between them increases. For this reason, the difference in transmittance between the blocks increases, and a so-called “block separation” occurs. As the size of the active matrix liquid crystal display device increases, the number of blocks in the photolithography process tends to increase. Therefore, it is desired to suppress the occurrence of block separation due to the coupling capacitance Csd. .
[0022]
  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an active matrix liquid crystal display device that can prevent deterioration in image quality due to coupling capacitance between a signal wiring and a pixel electrode, and can suppress block separation due to variation in the coupling capacitance. is there.
[0023]
[Means for Solving the Problems]
  To achieve the above objective,FirstThe invention of
  A plurality of scanning wirings formed on an insulating substrate, a plurality of signal wirings crossing the scanning wirings, a plurality of switching elements arranged in a matrix in the vicinity of each crossing position of the scanning wirings and the signal wirings, Formed via an interlayer insulating film above the signal wiring and the switching element in a region partitioned by the scanning wiring and the signal wiring, and arranged in a matrix connected to the output terminal of each switching element In an active matrix liquid crystal display device having a pixel electrode formed,
  The pixel electrode has, on one side, a first overlapping portion that completely overlaps the signal wiring adjacent to the one side and the entire width of the signal wiring through the interlayer insulating film, on the other side. A second overlapping portion that completely overlaps the signal wiring adjacent to the other side and the entire width of the signal wiring through the interlayer insulating film,
  The width and length of the region where the first overlapping portion overlaps the signal wiring are substantially the same as the width and length of the region where the second overlapping portion overlaps the signal wiring.The
  The signal wiring is first on both sides. , The second pixel electrode is bent at a substantially middle position in the extending direction of the signal wiring, and one of the two pixel electrodes overlaps the first pixel electrode with the bent portion as a boundary, and the other has the second pixel with the bent as a boundary. Overlapping the electrodesRu
It is characterized by that.
[0024]
  According to the above configuration, the first and second overlapping portions in which both side portions along the signal wiring in the pixel electrode completely overlap the two signal wirings adjacent to the pixel electrode and over the entire width of each signal wiring. The width and length of the region where the first overlapping portion overlaps the signal wiring and the width and length of the region where the second overlapping portion overlaps the signal wiring are substantially the same. Therefore, the difference between the first capacitance between the pixel electrode and the signal wiring adjacent on one side and the second capacitance between the pixel electrode and the signal wiring adjacent on the other side is the layer Even if there is a misalignment between, there is no significant change. As a result, block separation that occurs when the photolithography process is performed in units of blocks is suppressed.
[0025]
  Furthermore, a structure in which both side portions along the signal wiring in the pixel electrode completely overlap with the two signal wirings adjacent to the pixel electrode and the entire width of each signal wiring is achieved by using the rectangular pixel electrode. be able to. Accordingly, it is easy to form a color filter having substantially the same shape as the pixel electrode disposed on the counter substrate facing the insulating substrate, or a black matrix disposed at a position between adjacent image electrodes on the counter substrate. become.
[0026]
  Also,One embodimentIn the active matrix liquid crystal display device, it is desirable that the pixel electrode overlaps the switching element.
[0027]
  According to the above configuration, the pixel electrode can also be disposed on the switching element. Therefore, the pixel electrode can be arranged in a substantially rectangular shape, and the area of the pixel electrode is increased, thereby reducing power consumption..
[0028]
  MaTheOne embodimentIn the active matrix type liquid crystal display device, it is desirable that the switching element is disposed in the vicinity between two adjacent pixel electrodes.
[0029]
  According to the above configuration, the switching element is disposed in the vicinity of adjacent pixel electrodes that are regions that should be shielded from light. Therefore, it is not necessary to arrange a black matrix dedicated to the switching element, and an increase in the area of the black matrix can be prevented and a large aperture ratio can be obtained.
[0030]
  Also,SecondThe active matrix liquid crystal display device of the invention is
  A plurality of scanning wirings formed on an insulating substrate, a plurality of signal wirings crossing the scanning wirings, a plurality of switching elements arranged in a matrix in the vicinity of each crossing position of the scanning wirings and the signal wirings, Formed via an interlayer insulating film above the signal wiring and the switching element in a region partitioned by the scanning wiring and the signal wiring, and arranged in a matrix connected to the output terminal of each switching element In an active matrix liquid crystal display device having a pixel electrode formed,
  The pixel electrode has, on one side, a first overlapping portion that completely overlaps the signal wiring adjacent to the one side and the entire width of the signal wiring through the interlayer insulating film, on the other side. A second overlapping portion that completely overlaps the signal wiring adjacent to the other side and the entire width of the signal wiring through the interlayer insulating film,
  The width and length of the region where the first overlapping portion overlaps with the signal wiring are substantially the same as the width and length of the region where the second overlapping portion overlaps with the signal wiring,
  A counter substrate disposed to face the insulating substrate;
  A black matrix disposed on the counter substrate at a position facing between two adjacent pixel electrodes;
With
  In the black matrix, one side edge of the two adjacent pixel electrodes facing the pixel electrode on the side overlapping with the signal wiring includes the center line of the signal wiring and includes a center line. The other side edge of the counter electrode and the insulating substrate are aligned from the side edge of the signal wiring opposite to the inside of the pixel electrode toward the outside of the pixel electrode. Located more than margin
thingIt is characterized by.
[0031]
  According to the above configuration, the positions of both side edges of the black matrix arranged on the counter substrate are set in consideration of the alignment margin between the counter substrate and the insulating substrate. Therefore, even if there is a misalignment between the two substrates, the adjacent pixel electrodes are reliably shielded from light, and the block separation is further suppressed.
[0032]
  Further, in the active matrix liquid crystal display device according to one embodiment, the pixel electrode is formed with an extension portion on both side edges along the signal wiring, and the signal wiring adjacent to both sides is formed by the both extension portions. It is desirable that the first overlapping portion and the second overlapping portion overlap with each other.
[0033]
  According to the above configuration, a linear signal wiring has a structure in which both side portions along the signal wiring in the pixel electrode completely overlap with the two signal wirings adjacent to the pixel electrode over the entire width of each signal wiring. Can be achieved. Therefore, the length of the signal wiring can be shortened, and problems such as a delay of the source signal and a disconnection failure of the signal wiring generated when a large active matrix type liquid crystal display device of 15 inches or more is constructed are reduced.
[0034]
  Also,One embodimentThe active matrix liquid crystal display device preferably includes a light-shielding film disposed at a position between adjacent pixel electrodes on the insulating substrate.
[0035]
  In general, the alignment accuracy between the insulating substrate on which the pixel electrode is formed and the counter substrate facing the insulating substrate is about ± 5 μm, whereas the alignment accuracy between the layers on the insulating substrate is ± 5 μm. 1 μm or less. According to the above configuration, the light shielding film is disposed at a position between the adjacent pixel electrodes on the insulating substrate. Therefore, the width of the light-shielding film is formed narrower than the black matrix disposed on the counter substrate side, and the black matrix is deleted to improve the aperture ratio.
[0036]
  Furthermore, since the area of the black matrix disposed on the counter substrate side is reduced, a bonding margin between the insulating substrate and the counter substrate is widened.
[0037]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.
<First embodiment>
  FIG. 1 is a plan view of an active matrix substrate in the active matrix liquid crystal display device of the present embodiment. FIG. 2 is a cross-sectional view taken along the line AA ′ of FIG. 1 in the active matrix liquid crystal display device.
[0038]
  The active matrix substrate side has the following configuration. That is, in FIG. 1 and FIG. 2, a plurality of gate wirings (scanning wirings) 52 made of metal such as Al and Ta are arranged in parallel on an insulating substrate 51 made of glass as the active matrix substrate. The film thickness of the gate wiring 52 is 2000 to 5000 mm. Further, a plurality of source wirings 54 made of metal such as Al, Ta, etc. are disposed on the upper layer through a gate insulating film 53 made of SiNx or the like, perpendicular to the gate wiring 52. The thickness of the gate insulating film 53 is about 2000 to 4000 mm, and the relative dielectric constant is about 3 to 8. The film thickness of the source wiring 54 is 1000 to 5000 mm.
[0039]
  An amorphous silicon TFT 55 is arranged in the vicinity of each intersection position between the gate wiring 52 and the source wiring 54. The amorphous silicon TFT 55 is configured by laminating a gate electrode 56, a gate insulating film 53, an amorphous semiconductor layer 57, an impurity-added semiconductor layer 58, a source electrode 59 and a drain electrode 60. The gate electrode 56 is made of the same material as the gate wiring 52. Further, the source electrode 59 and the drain electrode 60 are made of the same material as the source wiring 54. The amorphous semiconductor layer 57 is made of amorphous silicon formed by CVD (Chemical Vapor Deposition) and has a thickness of about 500 to 2000 mm. The gate electrode 56 is connected to the adjacent gate line 52, and the source electrode 59 is connected to the adjacent source line 54.
[0040]
  Further, the previous-stage gate wiring 52a overlaps with the main-stage pixel electrode 62, and the drain electrode 60 extends through the gate insulating film 53 over the overlapping region in the previous-stage gate wiring 52a. A storage capacitor electrode 64 is formed by the end of the electrode 60. The interlayer insulating film 61 is made of an organic material or an inorganic material, and has a film thickness of 1 μm to 4 μm and a relative dielectric constant of about 2 to 4. A contact hole 65 is provided at the position of the auxiliary capacitance electrode 64 in the interlayer insulating film 61, and the drain electrode 60 is connected to the pixel electrode 62 by the contact hole 65 through the auxiliary capacitance electrode 64. That is, the previous gate wiring 52a is used as the auxiliary capacitance wiring for the main pixel.
[0041]
  In the present embodiment, a rectangular projecting portion 62a projecting from the side edge by a predetermined width is provided at the end of the pixel electrode 62 on the TFT 55 side. Similarly, a rectangular projecting portion 62b projecting from the side edge by the predetermined width is provided at the end of the other side of the pixel electrode 62 opposite to the TFT 55. The overhang amounts of the overhang portions 62a and 62b are made to overlap with the source wirings 54a and 54b located on both sides. The lengths of the overhang portions 62a and 62b are the same.
[0042]
  On the other hand, the counter substrate side has the following configuration. That is, on the insulating substrate 66 as the counter substrate made of glass, the color filters 67 are arranged at positions corresponding to the pixel electrodes 62 in the order of arrangement of red, green, and blue. Between the color filters 67 and 67, a black matrix 68 that is a light shielding film for preventing light leakage from between the pixel electrode 62, the adjacent pixel electrode 62, and the source wiring 54 is disposed. Further, a counter electrode 69 made of a transparent conductive material is disposed on the upper layer.
[0043]
  Then, the active matrix substrate 51 and the counter substrate 66 are arranged at a predetermined interval with the pixel electrode 62 side and the counter electrode 69 side facing each other, and the liquid crystal layer 70 is sandwiched between the substrates 51 and 66 with a sealing material. The active matrix type liquid crystal display device is configured by enclosing.
[0044]
  As described above, in the present embodiment, the overhang portions 62a and 62b are provided at the end portions on both sides of the pixel electrode 62 with the overhang amounts overlapping the adjacent source wirings 54a and 54b. The lengths of the two overhang portions 62a and 62b are the same. Furthermore, the length of the two overhang portions 62a and 62b is such that the distance between the one overhang portion 62a of the pixel electrode 62 and the other overhang portion 62b ′ of the adjacent pixel electrode 62 ′ is the same as that in the source wiring 54a. The interval is set such that the capacitance with the source wirings 54a and 54b generated in the region between the two overhang portions 62a and 62b ′ where the pixel electrode 62 does not overlap is negligible.
[0045]
  Therefore, in the above structure, the overhanging portions 62a and 62b of the pixel electrode 62 overlap or completely overlap the source wirings 54a and 54b, so that even if a slight misalignment occurs between the blocks in the photolithography process, The capacitance Csd1 and the capacitance Csd2 hardly change, and the transmittance difference between the blocks is also reduced.
[0046]
  Therefore, the value of (Csd1−Csd2) in the above formula (5) becomes substantially constant even if the blocks of the photolithography process are different, and the block separation can be prevented. FIG. 3 shows the photoalignment deviation dx and the amount of change in (Csd1-Csd2) between the active matrix liquid crystal display device in the present embodiment and the conventional active matrix liquid crystal display device shown in FIGS. As can be seen from FIG. 3, the change amount of (Csd1-Csd2) is reduced by adopting a structure in which the portions 62a, 62b on both sides of the pixel electrode 62 are completely overlapped on the source wirings 54a, 54b. Can do. As a result, block separation due to the above-described misalignment can be suppressed.
[0047]
  That is, according to the present embodiment, it is possible to suppress the block separation due to variations in the coupling capacitance Csd between the source wirings 54a and 54b and the pixel electrode 62.
[0048]
  <Second Embodiment>
  FIG. 4 is a plan view of an active matrix substrate in the active matrix liquid crystal display device of the present embodiment. FIG. 5 is a cross-sectional view taken along the line BB ′ of FIG. 4 in the active matrix liquid crystal display device.
[0049]
  4 and 5, the active matrix substrate 71, gate wiring 72, gate insulating film 73, TFT 75, interlayer insulating film 76, auxiliary capacitance electrode 78, contact hole 79, counter substrate 80, color filter 81, black matrix 82, counter The electrode 83 and the liquid crystal layer 84 are the active matrix substrate 51, the gate wiring 52, the gate insulating film 53, the TFT 55, the interlayer insulating film 61, the auxiliary capacitance electrode 64, and the contact hole 65 in the first embodiment shown in FIGS. , The counter substrate 66, the color filter 67, the black matrix 68, the counter electrode 69, and the liquid crystal layer 70 have the same configuration and function in the same manner.
[0050]
  The pixel electrode 77 according to the present embodiment is not provided with an overhanging portion that overlaps the source wiring 74 on both sides thereof, and has a linear shape and is formed in a rectangular shape. On the other hand, the source wiring 74 is bent at a position that bisects the pixel electrode 77 into the TFT 75 side and the anti-TFT 75 side. Then, about 1/2 of the bent portion of the source wiring 74 on the TFT 75 side overlaps with the pixel electrode 77 ′ located on one side via the interlayer insulating film 76. On the other hand, approximately 1/2 of the source wiring 74 on the side opposite to the TFT 75 from the bent portion overlaps with the pixel electrode 77 located on the other side via the interlayer insulating film 76.
[0051]
  Therefore, in the structure described above, a part of the both sides of the pixel electrode 77 overlaps or completely overlaps the source wirings 74 ′ and 74, so that even if a slight misalignment occurs between the blocks in the photolithography step, The capacitance Csd1 and the capacitance Csd2 hardly change, and the transmittance difference between the blocks is also reduced.
[0052]
  Furthermore, according to the present embodiment, the pixel electrode 77 can be formed in a rectangular shape as in the conventional active matrix liquid crystal display device shown in FIGS. Therefore, the color filter 81 and the black matrix 82 can be easily formed.
[0053]
  <Third Embodiment>
  FIG. 6 is a plan view of an active matrix substrate in the active matrix liquid crystal display device of the present embodiment. FIG. 7 is a cross-sectional view taken along the line CC ′ of FIG. 6 in the active matrix liquid crystal display device.
[0054]
  6 and 7, the active matrix substrate 91, the gate wiring 92, the gate insulating film 93, the source wiring 94, 94 ', the TFT 95, the interlayer insulating film 96, the auxiliary capacitance electrode 98, the contact hole 99, the counter substrate 100, and the color filter. 101, the black matrix 102, the counter electrode 103, and the liquid crystal layer 104 are the active matrix substrate 51, the gate wiring 52, the gate insulating film 53, the source wirings 54a and 54b, the TFT 55, the first embodiment shown in FIGS. The interlayer insulating film 61, the auxiliary capacitance electrode 64, the contact hole 65, the counter substrate 66, the color filter 67, the black matrix 68, the counter electrode 69, and the liquid crystal layer 70 have the same configuration and function in the same manner.
[0055]
  In the pixel electrode 97 according to the present embodiment, both side edges are bent at positions where the source lines 94 and 94 ′ are equally divided in the extending direction to form overhang portions on both sides. Then, a substantially 1/2 projecting portion on the TFT 95 side of the bent portion on one side portion of the pixel electrode 97 overlaps with the source wiring 94 ′ adjacent to the one side through the interlayer insulating film 96. . On the other hand, a substantially ½ overhanging portion on the other side of the pixel electrode 97 opposite to the bent portion of the pixel electrode 97 overlaps the source wiring 94 adjacent to the other side via the interlayer insulating film 96. ing.
[0056]
  Therefore, in the above structure, the protruding portion of the pixel electrode 97 overlaps or completely overlaps the source wirings 94 and 94 ′, so that the capacitance is not affected even if a slight misalignment occurs between the blocks in the photolithography process. Csd1 and capacitance Csd2 hardly change, and the transmittance difference between the blocks is also reduced.
[0057]
  Furthermore, according to the present embodiment, a bent portion is formed at the center of both sides of the pixel electrode 97 to form an overhang portion, and the source wire is formed by the overhang portion having a length that is approximately ½ of the side edge of the pixel electrode 97. 94 is covered. Therefore, as in the case of the first embodiment, the pixel electrode is compared with the case where the source wirings 54a and 54b are partially covered by the overhang portions 62a and 62b shorter than 1/2 of the side edge of the pixel electrode 62. The variation in the capacitance Csd between 97 and the source wiring 94 can be suppressed. Therefore, the block separation can be further reduced.
[0058]
  Further, since the pixel electrode 97 is bent on the source wirings 94 and 94 ′, the aperture ratio can be increased as compared with the case where the pixel electrode 97 is not. In particular, in a large-sized active matrix liquid crystal display device of 15 inches or more, a delay of a source signal, a disconnection failure of a source wiring, or the like becomes a problem. For this reason, it is necessary to shorten the wiring length of the source wiring as much as possible. The source wirings 94 and 94 ′ in the present embodiment are arranged in a straight line. Therefore, as compared with the case where the source line 74 is bent in the vicinity of each pixel electrode 77 as in the second embodiment shown in FIG. This is advantageous in terms of disconnection failure of the source wiring.
[0059]
  8 and 9 are a plan view of an active matrix substrate and a cross-sectional view of the active matrix liquid crystal display device corresponding to DD ′ in FIG. 8 in a modification of the present embodiment.
[0060]
  In this modification, the tips of the overhang portions 111a and 111b of the pixel electrode 111 extend beyond the source wiring 112 to the adjacent pixel side. By doing so, the pixel electrode 111 can be sufficiently overlapped with the source wiring 112, the alignment margin when forming the pixel electrode is further increased, and the above-mentioned block separation can be further suppressed.
[0061]
  The pixel electrode 111 is connected to the drain electrode 114 of the TFT 113 via the contact hole 115, and the auxiliary capacitance electrode 116 is connected to the pixel electrode 111 via the contact hole 117.
[0062]
  <Fourth embodiment>
  FIG. 10 is a plan view of an active matrix substrate in the active matrix liquid crystal display device of the present embodiment. FIG. 11 is a cross-sectional view taken along the line EE ′ of FIG. 10 in the active matrix liquid crystal display device.
[0063]
  10 and 11, the active matrix substrate 121, gate wiring 122, gate insulating film 123, source wiring 124, TFT 125, interlayer insulating film 126, pixel electrode 127, auxiliary capacitance electrode 128, contact hole 129, counter substrate 130, counter The electrode 133 and the liquid crystal layer 134 are the insulating substrate 91, the gate wiring 92, the gate insulating film 93, the source wiring 94, 94 ', the TFT 95, the interlayer insulating film 96, the pixel electrode in the third embodiment shown in FIGS. 97, the auxiliary capacitance electrode 98, the contact hole 99, the counter substrate 100, the counter electrode 103, and the liquid crystal layer 104 have the same configuration and function in the same manner.
[0064]
  In the present embodiment as well, as in the modification of the third embodiment, the tip of the protruding portion of the pixel electrode 127 extends beyond the source wiring 124 to the adjacent pixel side, The pixel electrode 127 is connected to the drain electrode 136 of the TFT 125 via the contact hole 137, and the auxiliary capacitance electrode 128 is connected to the pixel electrode 127 via the contact hole 129.
[0065]
  In the present embodiment, a light shielding film 135 made of the same material as the gate wiring 122 is disposed in the same layer as the gate wiring 122 so as to shield the adjacent pixel electrodes 127 and 127 from light. Therefore, it is not necessary to dispose the black matrix 132 at a position between the adjacent pixel electrodes 127 and 127 on the counter substrate 130, and the black matrix 132 may be formed only on the TFT 125.
[0066]
  In general, the alignment accuracy between the active matrix substrate 121 and the counter substrate 130 is about ± 5 μm. On the other hand, the alignment accuracy between the layers of the active matrix substrate 121 is ± 1 μm or less. Therefore, by arranging the light shielding film 135 on the active matrix substrate 121 side, the width of the light shielding film 135 can be made narrower than that of the black matrix 132 and the black matrix 132 can be deleted. As a result, the area of the color filter 131 can be increased and the aperture ratio can be improved.
[0067]
  Furthermore, since the area of the black matrix 132 disposed on the counter substrate 130 side is reduced, the bonding margin between the active matrix substrate 121 and the counter substrate 130 can be widened.
[0068]
  In the present embodiment, the arrangement of the light shielding film 135 and the deletion of the black matrix 132 thereby applied are applied to the third embodiment, but the first and second embodiments are applied. It doesn't matter if it is applied.
[0069]
  In each of the above embodiments, the TFTs 55, 75, 95, 113, and 125 are connected to the pixel electrodes 62, 77, 97, 111, 127 adjacent to each other and the pixel electrodes 62, 77, 97, 111, 127. In the lower layer in the vicinity of the gap, the interlayer insulating films 61, 76, 96, and 126 are disposed. Therefore, the black matrices 68, 82, 102, and 132 are originally arranged in the vicinity of the region where they should be arranged. Therefore, it is not necessary to arrange a black matrix dedicated to the TFTs 55, 75, 95, 113, and 125, and the area of the black matrices 68, 82, 102, and 132 can be prevented from increasing more than necessary. Therefore, the aperture ratio can be increased.
[0070]
  Further, in each of the above embodiments, the formation regions of the black matrices 68, 82, 102, 132 are set as follows. That is, one side edge facing the pixel electrode on the side covering the source wiring is a position facing between the two adjacent pixel electrodes on the counter substrate. It is set so as to be located inside the pixel electrode (in the case of FIG. 1) from the center line including the center line of the source wiring (in the case of FIGS. 4, 6, 8, and 10). On the other hand, the other side edge is set so as to be located more than the alignment margin between the counter substrate and the active matrix substrate from the side edge of the signal wiring opposite to the pixel electrode.
[0071]
  By doing so, the positions of both side edges of the black matrices 68, 82, 102, 132 arranged on the counter substrate are set in consideration of the alignment margin between the counter substrate and the active matrix substrate. Therefore, even if there is a misalignment between the two substrates, the pixel electrodes adjacent to each other can be reliably shielded from light, and the block separation can be further suppressed.
[0072]
  In each of the above embodiments, the bent portions of the pixel electrodes 97, 111, 127 and the bent portion of the source wiring 74 are provided at the center positions of the pixel electrodes 77, 97, 111, 127. However, in order to suppress the shadowing phenomenon and the block separation, it is not necessary to provide the bent portion strictly at the center of the pixel electrode. Therefore, the present invention does not limit the position of the bent portion provided in the pixel electrode or the source wiring to only the center position of each pixel electrode.
[0073]
  In addition, the present invention may have a portion that is not covered slightly in the width direction of the source wiring (signal wiring) on both side portions (projecting portions) of the pixel electrode to the extent that the same effects as those of the above embodiments are obtained. Absent.
[0074]
【The invention's effect】
  As is clear from the above,FirstInventionActive matrix liquid crystal display deviceHas both the two signal wirings adjacent to the pixel electrode and first and second overlapping portions that completely overlap the entire width of each signal wiring on both sides of the pixel electrode along the signal wiring, The width and length of the region where the first overlapping portion overlaps the signal wiring and the width and length of the region where the second overlapping portion overlaps the signal wiring are substantially the same. Accordingly, the difference between the first capacitance between the pixel electrode and the signal wiring adjacent to one side and the second capacitance between the pixel electrode and the signal wiring adjacent to the other side is expressed as a layer. Even if there is a misalignment between them, it can be prevented from changing significantly. That is, according to the present invention, it is possible to suppress block separation that occurs when the photolithography process is performed in units of blocks.
[0075]
  Further, the signal wiring is arranged on the first side located on both sides. , The second pixel electrode is bent at a substantially intermediate position in the extending direction of the signal wiring. One of the second pixel electrodes overlaps the first pixel electrode with the bent portion as a boundary, and the other with the bent as the boundary is the second pixel. Since the pixel electrodes overlap each other, both sides along the signal wiring in the pixel electrode completely overlap the two signal wirings adjacent to the pixel electrode and the entire width of each signal wiring. It can be obtained using an electrode. Therefore, it is possible to easily form the color filter disposed on the counter substrate facing the insulating substrate and the black matrix disposed at the position between the adjacent image electrodes on the counter substrate.
[0076]
  Also,In one embodimentIf the pixel electrode overlaps the switching element, the pixel electrode can also be arranged on the switching element. Therefore, the pixel electrode can be arranged in a substantially rectangular shape, and the power consumption can be suppressed by increasing the area of the pixel electrode..
[0077]
  MaTheIn one embodimentIf the switching element is disposed in the vicinity between two adjacent pixel electrodes, the switching element is disposed in the vicinity between adjacent pixel electrodes, which are areas to be shielded from each other. Therefore, it is not necessary to arrange a black matrix dedicated to the switching element, and an increase in the area of the black matrix can be prevented and a large aperture ratio can be obtained.
[0078]
  Also,SecondIn the active matrix type liquid crystal display device according to the present invention, when a black matrix that shields light between adjacent pixel electrodes is arranged on a counter substrate facing the insulating substrate, the pixel on the side overlapping the signal wiring is disposed. One side edge facing the electrode is located inside the pixel electrode with respect to the center line including the center line of the signal wiring, while the other side edge is opposite to the inside of the pixel electrode in the signal wiring. From the side edge toward the outside of the pixel electrode so as to be positioned more than the alignment margin between the counter substrate and the insulating substrate.BecauseThe arrangement position of the black matrix can be set in consideration of the alignment margin between the counter substrate and the insulating substrate. Therefore, even if there is misalignment between the two substrates, it is possible to reliably shield light between adjacent pixel electrodes, and further suppress the block separation.
[0079]
  Further, in one embodiment, an extension portion is formed on both sides of the pixel electrode, and the first overlap portion and the second overlap portion that overlap the signal wiring adjacent to both sides are formed by the both extension portions. Using a linear signal wiring, a structure in which both side portions along the signal wiring in the pixel electrode completely overlap with the two signal wirings adjacent to the pixel electrode and over the entire width of each signal wiring is obtained. Can do. Therefore, the length of the signal wiring can be shortened, and problems such as a delay of the source signal and a disconnection failure of the signal wiring generated when a large active matrix type liquid crystal display device of 15 inches or more is constructed can be reduced.
[0080]
  Also,In one embodimentIf a light shielding film is disposed at a position between adjacent pixel electrodes on the insulating substrate, the alignment accuracy between the layers on the insulating substrate is smaller than the alignment accuracy between the insulating substrate and the counter substrate. The width of the light shielding film can be made narrower than that of the black matrix disposed on the counter substrate side. Therefore, combined with the fact that the black matrix can be deleted, the aperture ratio can be improved.
[0081]
  Furthermore, since the area of the black matrix disposed on the counter substrate side is reduced, the bonding margin between the insulating substrate and the counter substrate can be widened.
[Brief description of the drawings]
FIG. 1 is a plan view of an active matrix substrate in an active matrix liquid crystal display device of the present invention.
FIG. 2 is a cross-sectional view taken along the line AA ′ in FIG.
FIG. 3 is a diagram illustrating a photoalignment shift and a coupling capacitance change amount;
FIG. 4 is a plan view of an active matrix substrate different from FIG.
5 is a cross-sectional view taken along the line BB ′ in FIG.
6 is a plan view of an active matrix substrate different from FIGS. 1 and 4. FIG.
7 is a cross-sectional view taken along the line CC ′ in FIG.
8 is a plan view of an active matrix substrate different from those of FIGS. 1, 4 and 6. FIG.
FIG. 9 is a cross-sectional view taken along the line DD ′ in FIG.
10 is a plan view of an active matrix substrate different from FIGS. 1, 4, 6 and 8. FIG.
11 is a cross-sectional view taken along the line EE ′ in FIG.
FIG. 12 is a plan view of a general active matrix liquid crystal display device.
13 is a cross-sectional view of one pixel portion of the active matrix liquid crystal display device shown in FIG.
14 is a plan view of one pixel portion of the active matrix liquid crystal display device shown in FIG.
FIG. 15 is a cross-sectional view of a conventional active matrix liquid crystal display device in which pixel electrodes are overlaid on signal wirings.
16 is a plan view of the active matrix substrate in FIG. 15. FIG.
FIG. 17 is an equivalent circuit diagram of the active matrix substrate shown in FIG.
FIG. 18 is an explanatory diagram of misalignment of pixel electrodes.
FIG. 19 is a diagram illustrating a relationship between misalignment of a pixel electrode and capacitance between the pixel electrode / adjacent signal lines.
FIG. 20 is a diagram illustrating a relationship between misalignment and transmittance difference with respect to a block having no misalignment.
[Explanation of symbols]
  51, 71, 91, 121 ... active matrix substrate,
52, 52a, 72, 92, 122 ... gate wiring (scanning wiring),
54a, 54b, 74, 94, 112, 124 ... source wiring (signal wiring),
55,75,95,113,125 ... TFT,
60, 114, 136 ... drain electrodes,
61, 76, 96, 126 ... interlayer insulating film,
62, 77, 97, 111, 127 ... pixel electrodes,
64, 78, 98, 116, 128 ... auxiliary capacitance electrodes,
65, 79, 99, 115, 117, 129, 137 ... contact holes,
66, 80, 100, 130 ... counter substrate,
67, 81, 101, 131 ... color filters,
68, 82, 102, 132 ... black matrix,
69, 83, 103, 133 ... counter electrode,
70, 84, 104, 134 ... liquid crystal layer,
135: light shielding film.

Claims (9)

A plurality of scanning wirings formed on an insulating substrate, a plurality of signal wirings crossing the scanning wirings, a plurality of switching elements arranged in a matrix in the vicinity of each crossing position of the scanning wirings and the signal wirings, Formed via an interlayer insulating film above the signal wiring and the switching element in a region partitioned by the scanning wiring and the signal wiring, and arranged in a matrix connected to the output terminal of each switching element In an active matrix liquid crystal display device having a pixel electrode formed,
The pixel electrode has, on one side, a first overlapping portion that completely overlaps the signal wiring adjacent to the one side and the entire width of the signal wiring through the interlayer insulating film, on the other side. A second overlapping portion that completely overlaps the signal wiring adjacent to the other side and the entire width of the signal wiring through the interlayer insulating film,
The first overlapping portion and the width and length of the region of overlap with the signal line, Ri width and length substantially the same der the region where the second overlapping portion overlaps with the signal line,
The signal wiring is bent at a substantially intermediate position in the extending direction of the signal wiring in the first and second pixel electrodes located on both sides, and one of the signal wirings overlaps the first pixel electrode with the bent portion as a boundary, the bending in the boundary and the other is an active matrix type liquid crystal display device which is characterized that you have overlapped with the second pixel electrode. The active matrix liquid crystal display device according to claim 1,
An active matrix liquid crystal display device, wherein the pixel electrode overlaps with the switching element. The active matrix liquid crystal display device according to claim 1 or 2,
An active matrix liquid crystal display device, wherein the switching element is disposed in the vicinity of two adjacent pixel electrodes. A plurality of scanning wirings formed on an insulating substrate, a plurality of signal wirings crossing the scanning wirings, a plurality of switching elements arranged in a matrix in the vicinity of each crossing position of the scanning wirings and the signal wirings, Formed via an interlayer insulating film above the signal wiring and the switching element in a region partitioned by the scanning wiring and the signal wiring, and arranged in a matrix connected to the output terminal of each switching element In an active matrix liquid crystal display device having a pixel electrode formed ,
The pixel electrode has, on one side, a first overlapping portion that completely overlaps the signal wiring adjacent to the one side and the entire width of the signal wiring through the interlayer insulating film , on the other side. A second overlapping portion that completely overlaps with the signal wiring adjacent to the other side and the entire width of the signal wiring through the interlayer insulating film ,
The width and length of the region where the first overlapping portion overlaps with the signal wiring are substantially the same as the width and length of the region where the second overlapping portion overlaps with the signal wiring,
A counter substrate disposed to face the insulating substrate;
A black matrix disposed on the counter substrate at a position facing between two adjacent pixel electrodes;
With
In the black matrix, one side edge of the two adjacent pixel electrodes facing the pixel electrode on the side overlapping with the signal wiring includes the center line of the signal wiring and includes a center line. The other side edge of the counter electrode and the insulating substrate are aligned from the side edge of the signal wiring opposite to the inside of the pixel electrode toward the outside of the pixel electrode. An active matrix type liquid crystal display device, characterized in that the active matrix type liquid crystal display device is located more than a margin . In an active matrix liquid crystal display device according to 請 Motomeko 4,
An active matrix liquid crystal display device , wherein the pixel electrode overlaps with the switching element. In the active matrix type liquid crystal display device according to claim 4 or 5 ,
The signal wiring is bent at a substantially intermediate position in the extending direction of the signal wiring in the first and second pixel electrodes located on both sides, and one of the signal wirings overlaps the first pixel electrode with the bent portion as a boundary , An active matrix type liquid crystal display device, wherein the other is overlapped with the second pixel electrode with the bend as a boundary . In the active matrix type liquid crystal display device according to claim 4 or 5 ,
Upper outs pixel electrodes are projecting portion is formed on both side edges along the signal line, by the two overhang, the first overlapping portion overlapping the signal lines adjacent to each side and the second overlapping portion active matrix liquid crystal display device according to claim <br/> that constitute the. The active matrix liquid crystal display device according to any one of claims 4 to 7,
An active matrix liquid crystal display device, wherein the switching element is disposed in the vicinity of two adjacent pixel electrodes. The active matrix liquid crystal display device according to any one of claims 1 to 8,
An active matrix liquid crystal display device, comprising: a light shielding film disposed at a position between adjacent pixel electrodes on the insulating substrate.

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