JP2005049894A - Active matrix liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To optimize a liquid crystal display device using low-temperature polycrystalline TFTs. <P>SOLUTION: The TFTs using a low-temperature polycrystalline thin film 20 as an active layer are formed on a TFT substrate 10 and a plurality of pixel electrodes 26 are formed across interlayer insulation films thereon so as to cover the TFTs and electrode wiring. Orientation control windows 34 for liquid crystals are formed in the prescribed positions facing the respective pixel electrodes 26 on a common electrode 34 formed on a counter substrate 30 facing the above substrate across a liquid crystal layer 40. The orientation region of liquid crystal molecules is divided within one pixel region to realize a wider angle of view. The orientation of the liquid crystal layer 40 is perpendicular orientation and the liquid crystal material includes fluorine-based liquid crystal molecules having negative dielectric anisotropy and having fluorine in at least the side chains, by which the sufficient operation by the low-voltage driving realized by the polycrystalline TFTs is made possible. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention uses an active matrix type liquid crystal display (LCD) that drives a pixel by a thin film transistor (TFT) to display a liquid crystal, and in particular, uses polycrystalline silicon produced by a low temperature process for the thin film transistor. The present invention relates to a liquid crystal display device.

  A liquid crystal display device in which a liquid crystal is sealed between a pair of substrates and a voltage is applied to the liquid crystal to perform a desired display has an advantage of being small and thin, and is easy to reduce power consumption. It has been put into practical use as a display for various OA equipment, AV equipment, portable information equipment, and in-vehicle information equipment. In particular, a so-called active matrix type liquid crystal display device using a thin film transistor (hereinafter referred to as TFT) as a switching element for driving each liquid crystal pixel can selectively drive the TFT to select a liquid crystal pixel. High-definition image display without talk is possible.

  As TFTs used in liquid crystal display devices, amorphous silicon TFTs using amorphous silicon for active layers and polycrystalline silicon TFTs using polycrystalline silicon having high mobility due to active layers are known. Since amorphous silicon TFTs can be formed over a large area by a low temperature process, they are often used for large displays. In contrast, a polycrystalline silicon TFT has higher mobility than amorphous silicon and can form an element by self-alignment. Therefore, a TFT area and a pixel area are smaller than those of an amorphous silicon TFT. Easy to do and can produce a high definition display. If polycrystalline silicon is used, it is easy to make the TFT have a CMOS structure, so that a driver TFT for driving the display portion TFT can be formed on the same substrate through substantially the same process as the display portion TFT.

  It is known that a polycrystalline silicon TFT having excellent characteristics and having a built-in driver on a substrate can be formed by polycrystallizing amorphous silicon by a high temperature process, but is exposed to a high temperature during the process. For this reason, an inexpensive glass substrate cannot be used as the substrate, which is difficult to put into practical use.

  However, improvement of the polycrystallization technique using annealing treatment such as laser annealing or lamp annealing has made it possible to produce polycrystalline silicon by a low temperature process. As described above, the method of forming the polycrystalline silicon TFT by the low temperature process can use an inexpensive glass substrate as the substrate, so that the cost can be reduced and the area can be increased, and the polycrystalline silicon TFT by the low temperature process can be achieved. (Hereinafter referred to as low-temperature polycrystalline silicon TFT) has been put into practical use.

  Although low-temperature polycrystalline silicon TFTs are being put to practical use in this way, the best liquid crystal materials and optimal liquid crystal display devices can be used to maximize the characteristics of low-temperature polycrystalline silicon TFTs as a liquid crystal display device. Development of the panel configuration is still not progressing. For this reason, for example, the materials and structures used in conventional liquid crystal display devices for amorphous silicon TFTs are used as they are, and the characteristics of polycrystalline silicon TFTs cannot be fully exhibited. was there.

  In order to solve the above problems, in the active matrix type liquid crystal display device according to the present invention, an appropriate liquid crystal material or panel configuration is obtained in order to obtain a liquid crystal display device capable of maximizing the use of the characteristics of the low-temperature polycrystalline silicon TFT. Propose.

  First, the present invention includes a plurality of pixel electrodes provided in a matrix on a first substrate, a thin film transistor formed so as to be connected to the corresponding pixel electrode, and an electrode wiring thereof. An active matrix type in which a liquid crystal layer sandwiched between the plurality of pixel electrodes on one substrate and a common electrode on a second substrate disposed opposite to the first substrate is driven for each pixel electrode. In the liquid crystal display device, a polycrystalline silicon thin film transistor using a polycrystalline silicon layer formed at a low temperature as an active layer is used as the thin film transistor, and each of the liquid crystal layers sandwiched between the first and second substrates is used. The initial alignment of liquid crystal molecules is controlled to be substantially perpendicular to the pixel electrode, and the liquid crystal material used for the liquid crystal layer includes fluorine in the side chain. Among the materials with a molecular structure represented by 6), selecting at least one kind of liquid crystal molecules. A liquid crystal molecule having fluorine in the side chain has a high polarity in the side chain direction, that is, the minor axis direction of the liquid crystal molecule, and can operate sufficiently even at a low driving voltage realized by a polycrystalline silicon thin film transistor. In addition, the high polarity in the minor axis direction makes it easy to make the initial alignment of the liquid crystal vertical, for example, by increasing the repulsion with the liquid crystal alignment film.

  In the present invention, the common electrode on the second substrate is provided with an electrode absent portion for controlling the alignment of the liquid crystal in a predetermined corresponding region facing the pixel electrode as an alignment control window. A plurality of regions having different inclination directions are created in each pixel electrode region while changing the orientation from the vertical direction. Since the alignment region of the liquid crystal molecules is stably divided by the alignment control window, a plurality of priority viewing directions can be provided in the display device, and the viewing angle is expanded.

  Further, in the present invention, a planarizing interlayer insulating film is formed on the first substrate so as to cover the thin film transistor formed on the first substrate and the electrode wiring thereof, and the planarizing interlayer insulating film is formed on the planarizing interlayer insulating film. A plurality of pixel electrodes are respectively formed. By forming the pixel electrode on the planarized interlayer insulating film, the unevenness of the pixel electrode does not adversely affect the vertical alignment of the liquid crystal molecules. Further, by forming a pixel electrode on the planarized interlayer insulating film so as to cover at least a thin film transistor formation region (for example, to cover the thin film transistor and its electrode wiring), an electric field generated by the thin film transistor or the like is applied to the liquid crystal layer. Prevent leakage. In addition, it is easy to efficiently apply a voltage to the liquid crystal layer by positioning the pixel electrode in the upper layer.

  Furthermore, in the active matrix liquid crystal display device, the liquid crystal material used for the liquid crystal layer has negative dielectric anisotropy, and the vertical alignment of the liquid crystal layer can be performed without performing a rubbing process, It is controlled by a vertical alignment film formed so as to cover each of the pixel electrodes, the alignment control window provided in the common electrode, and a voltage applied to each of the plurality of pixel electrodes. Even when a driving circuit comprising thin film transistor groups having substantially the same structure as the polycrystalline silicon thin film transistor is formed in the peripheral portion of the first substrate by vertically aligning the liquid crystal layer without a rubbing process, The transistor is prevented from being adversely affected by rubbing.

  As described above, according to the present invention, when a low-temperature polycrystalline silicon TFT that can be driven on the same substrate and can be driven at a low voltage is used as an element for driving a liquid crystal, the liquid crystal material is negative. By using liquid crystal molecules having a dielectric anisotropy of at least a fluorine in the side chain, the liquid crystal layer can be sufficiently driven even at a low voltage. Further, the liquid crystal layer exhibits a sufficiently high voltage holding ratio even when driven at a low voltage suitable for a polycrystalline silicon TFT, and burn-in is prevented. In addition, since the liquid crystal display device can be driven at a low voltage, power consumption of the liquid crystal display device can be reduced.

  In addition, by providing an alignment control window in the area facing each pixel electrode of the common electrode, the orientation of the liquid crystal molecules is divided within one pixel area, thereby reducing the visual dependency of the liquid crystal display device, and displaying This is also advantageous when the apparatus is enlarged.

  Further, since the planarization interlayer insulating layer is formed so as to cover the thin film transistor and the pixel electrode is formed thereon, the aperture ratio of the display device can be improved and the flatness of the pixel electrode can be ensured without performing the rubbing process. It is easy to prevent the disorder of the alignment of the vertically aligned liquid crystal molecules. Furthermore, by disposing the pixel electrode above the thin film transistor, the electric field from the thin film transistor and the electrode wiring therefor can be prevented from leaking into the liquid crystal layer and adversely affecting the alignment, and the liquid crystal layer can be sufficiently controlled even at low voltage drive. It becomes possible to do. In addition, since the initial alignment of the liquid crystal layer can be made vertical without a rubbing step, even if the driver TFT is built on the same substrate as the low-temperature polycrystalline silicon TFT for driving the liquid crystal, This eliminates the possibility of damaging the driver TFT formed in the peripheral region of the substrate, and is suitable for a liquid crystal display device using a polycrystalline silicon TFT having a built-in driver.

  Hereinafter, preferred embodiments of the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

  FIG. 1 shows an example of a planar configuration for one pixel of an active matrix liquid crystal display device according to an embodiment of the present invention, and FIG. 2 shows an example of a schematic cross section taken along line AA of FIG. The active matrix liquid crystal display device according to this embodiment includes a TFT substrate (first substrate) 10 in which a low-temperature polycrystalline silicon TFT is formed and a pixel electrode 26 is disposed in an upper layer, and a liquid crystal layer between the TFT substrate 10. A counter substrate (second substrate) 30 is provided so as to face the substrate 40, and polarizing plates 44 and 46 are provided outside the substrates 10 and 30 so that their transmission polarization directions are orthogonal to each other. It has been.

On the TFT substrate 10 made of glass or the like, in the example shown in FIG. 2, a gate electrode 12 obtained by patterning a metal such as Cr, Ta, and Mo and a gate electrode wiring 12 </ b> L integrated with the gate electrode 12 are provided. A gate insulating film 14 made of, for example, a laminated structure of SiNx and SiO ₂ or one of them is formed so as to cover the gate electrode 12 and the gate electrode wiring 12L. A polycrystalline silicon thin film 20 that functions as an active layer of the TFT is formed on the gate insulating film 14. The polycrystalline silicon thin film 20 is polycrystallized by subjecting the amorphous silicon thin film to a low temperature annealing treatment using a combination of laser annealing and lamp annealing or one of the annealing treatments, and then patterning into an island shape. It is obtained.

An injection stopper 23 made of SiO ₂ or the like is formed on the polycrystalline silicon thin film 20. The injection stopper 23 is formed by being patterned from the back surface (lower side in FIG. 2) of the TFT substrate 10 with the gate electrode 12 as a mask so as to be patterned in substantially the same shape as the gate electrode 12 in a self-aligning manner. Then, by using this implantation stopper 23, impurities such as phosphorus and arsenic are implanted at a low concentration into the polycrystalline silicon thin film 20, so that both sides of the region immediately below the implantation stopper 23 of the polycrystalline silicon thin film 20 are self-aligned. Thus, a low-concentration source region 20LS and a low-concentration drain region 20LD containing these impurities at a low concentration are formed. In addition, the region immediately below the implantation stopper 23 becomes an intrinsic region that does not substantially contain impurities because the implantation stopper 23 serves as a mask and is not implanted with impurities, and this intrinsic region functions as the channel region 20CH of the TFT. A source region 20S and a drain region 20D are formed outside the low concentration source region 20LS and the low concentration drain region 20LD by implanting the same impurity at a higher concentration.

  An interlayer insulating film 22 made of SiNx or the like is formed on the polycrystalline silicon thin film 20 in which each region (20CH, 20LS, 20LD, 20S, 20D) is formed and the injection stopper 23 so as to cover them. On the interlayer insulating film 22, a source electrode 16 made of Al, Mo, or the like, a drain electrode 18, and a drain electrode wiring 18 </ b> L integrated with the drain electrode 18 are formed. The source electrode 16 and the drain electrode 18 are connected to a source region 20S and a drain region 20D formed in the polycrystalline silicon thin film 20 through contact holes provided in the interlayer insulating film 22.

  The low-temperature polycrystalline silicon TFT in this embodiment includes the gate electrode 12, the gate insulating film 14, the polycrystalline silicon thin film 20 (20CH, 20LS, 20LD, 20S, 20D), the source electrode 16, and the drain electrode 18, and includes a low-temperature process. The gate electrode 12 is composed of an inverted stagger type TFT having the polycrystalline silicon thin film 20 formed in (1) as an active layer and the gate electrode 12 positioned below the element. However, the TFT shape is not limited to the inverted stagger type, and may be a stagger type configuration in which the gate electrode is arranged in an upper layer than the polycrystalline silicon thin film.

  A flattening interlayer insulating film 24 for further flattening is formed to a thickness of about 1 μm or more on almost the entire surface of the TFT substrate 10 so as to cover the TFT having such a configuration and the interlayer insulating film 22. . For example, SOG (Spin On Grass), BPSG (Boro-phospho-Silicate Glass), acrylic resin, or the like is used for the planarization interlayer insulating film 24. On the planarization interlayer insulating film 24, when the display device is a transmission type, a liquid crystal driving pixel electrode 26 using a transparent conductive film such as ITO (Indium Tin Oxide) is formed so as to cover the TFT formation region. The pixel electrode 26 is connected to the source electrode 16 through a contact hole provided in the planarization interlayer insulating film 24. When the display device is of a reflective type, a conductive reflective material such as Al is used for the pixel electrode 26.

  A vertical alignment film 28 using, for example, polyimide (SiNx) is formed on almost the entire surface of the TFT substrate 10 so as to cover the pixel electrode 26 as an alignment film for aligning liquid crystal molecules in the vertical direction without a rubbing process. ing.

  A counter substrate (second substrate) 30 disposed opposite to the TFT substrate 10 on which each element as described above is sandwiched with the liquid crystal layer 40 is made of glass or the like, like the TFT substrate 10. An RGB color filter 38 is formed on the surface opposite to the substrate 10, and further, a common film made of ITO or the like for driving the liquid crystal with the pixel electrode 26 facing through a protective film 36 such as an acrylic resin. An electrode 32 is formed. In this embodiment, as will be described later, the common electrode 32 is formed with an X-shaped electrode absent portion as shown in FIG. 2, for example, as an alignment control window 34 in a region facing each pixel electrode 26. Has been. On the common electrode 32 and the alignment control window 34, a vertical alignment film 28 similar to that on the TFT substrate 10 side is formed so as to cover them.

  The liquid crystal layer 40 is sealed in a gap between substrates set to about 3 μm, for example, and the liquid crystal material is a so-called negative dielectric whose dielectric constant in the minor axis direction is larger than the dielectric constant in the major axis direction of the liquid crystal molecules 42. A liquid crystal material having a rate anisotropy is used. In the present embodiment, the liquid crystal material used for the liquid crystal layer 40 is a mixture of liquid crystal molecules having a structure represented by chemical formulas (1) to (6) having fluorine in the side chain as described above in a desired ratio. These are mixed so as to include at least one kind of liquid crystal molecules represented by the chemical formulas (1) to (6).

  Currently, liquid crystal molecules having negative dielectric anisotropy include liquid crystal molecules having a cyano (CN-) group in the side chain for TFT liquid crystal display devices using amorphous silicon having low mobility as an active layer. Mainly used. However, a liquid crystal molecule having a cyano group in the side chain has a residual DC voltage when driven at a low voltage, so it needs to be driven at a sufficiently high voltage, has a low voltage holding ratio, and may cause liquid crystal burn-in. . However, in this embodiment, a polycrystalline silicon TFT which is manufactured by a low temperature process and can be driven at a low voltage is used as the TFT. Therefore, if a liquid crystal material having a cyano group currently used in the side chain is used, the characteristics of the polycrystalline silicon TFT that can be driven at a low voltage cannot be utilized. Therefore, as shown in the above chemical formulas (1) to (6) as the liquid crystal material, by adding liquid crystal molecules having fluorine in the side chain, the polarity of the side chain is increased. In the range of −20 ° C. to 80 ° C. or higher, driving at a low voltage of about 2 V is possible, and furthermore, a sufficiently high voltage holding ratio is provided even at low voltage driving by a polycrystalline silicon TFT, and burn-in is prevented. In addition, since the liquid crystal display device can be driven at a low voltage, a device with lower power consumption than a liquid crystal display device using amorphous silicon TFTs can be provided.

  In this embodiment, the initial alignment of liquid crystal molecules is controlled in the vertical direction by using a liquid crystal material containing fluorine-based liquid crystal molecules having negative dielectric anisotropy as described above and using the vertical alignment film 28. A DAP (deformation of vertically aligned phase) type orientation control is performed. The DAP type is a type of voltage controlled birefringence (ECB) method, which utilizes the difference in refractive index between the major and minor axes of liquid crystal molecules, that is, the light incident on the liquid crystal layer using the birefringence phenomenon. It controls the transmittance.

  When a voltage is applied to the liquid crystal layer 40, the DAP type liquid crystal display device passes through one of polarizing plates 44 and 46 arranged orthogonal to each other outside the TFT substrate 10 and the counter substrate 30 and enters the liquid crystal layer 40. By making the linearly polarized light into elliptically polarized light and further circularly polarized light by birefringence, incident light can be emitted from the other polarizing plate. When no voltage is applied to the liquid crystal layer 40, the liquid crystal molecules are vertically aligned by the vertical alignment film 28, so that light incident on the liquid crystal layer 40 from one polarizing plate is not subjected to birefringence and the other polarization It is not ejected from the board. That is, in this DAP type, the amount of birefringence, that is, the phase difference (retardation amount) between the ordinary light component and the extraordinary light component of the incident linearly polarized light is determined according to the electric field strength in the liquid crystal layer 40, and the voltage applied to the liquid crystal layer 40 is reduced. A so-called normally black mode display in which the display changes from black to white as it rises is performed. Then, by controlling the voltage applied to the liquid crystal layer 40 for each pixel, the amount of light emitted from the other polarizing plate, that is, the transmittance is controlled for each pixel, so that a desired image display can be performed on the entire display device. ing.

  Furthermore, in the present embodiment, as shown in FIGS. 1 and 2, by providing the common electrode 32 with an alignment control window 34 as an electrode absent portion, the alignment control window 34 is tilted in a predetermined direction with reference to the liquid crystal molecules. In addition to improving the responsiveness, the viewing angle dependence of the liquid crystal display is relaxed by dividing the alignment direction in the pixel, thereby realizing a display device with a wide viewing angle. When a voltage is applied to the liquid crystal layer 40, oblique electric fields are generated in different directions between the common electrode 32 and the edge portion of each side of the pixel electrode 26 shown in FIG. Therefore, at the edge portion of the side of the pixel electrode 26, the liquid crystal molecules are inclined from the vertical alignment state to the opposite side of the inclination of the oblique electric field. Since the liquid crystal molecules 42 have continuity, when the tilt direction of the liquid crystal molecules is determined by an oblique electric field at the edge portion of the pixel electrode 26 (the tilt angle is determined by the electric field strength), the liquid crystal near the center of the pixel electrode 26 is displayed. The direction in which the molecules incline follows the direction of inclination of the liquid crystal molecules on each side of the pixel electrode 26, and a plurality of regions having different directions of inclination of the liquid crystal molecules are generated in one pixel region.

  On the other hand, since only a voltage lower than the liquid crystal operation threshold is always applied to the alignment control window 34, the liquid crystal molecules located in the alignment control window 34 remain vertically aligned as shown in FIG. For this reason, the alignment control window 34 is always a boundary between regions having different tilt directions of the liquid crystal molecules. For example, if the orientation control window 34 has an X shape as shown in FIG. 1, the boundaries of the regions A, B, C, and D having different inclination directions are fixed on the X shape orientation control window 34. The Rukoto.

  As described above, in the DAP type liquid crystal display device, the transmittance varies depending on the tilt of the liquid crystal molecules with respect to incident light. Therefore, if the tilt direction of the liquid crystal molecules in one pixel region is one direction, the priority viewing angle direction also corresponds. It is limited to the direction, and the viewing angle dependency becomes strong. In addition, even when there are a plurality of regions with different inclination directions in one pixel region, if the boundary of the regions with the inclination changes for each selection period, the display becomes rough and the display quality deteriorates. Invite. On the other hand, in the present embodiment, not only alignment division is performed within one pixel region, but also boundaries of regions inclined in different directions can be fixed on the alignment control window 34, and the preferred viewing angle direction Can be provided (in the case of the present embodiment, four vertically and horizontally), and a liquid crystal display device with a wide viewing angle can be obtained.

  Further, in the present embodiment, as described above, the pixel electrode 26 is formed so as to cover the formation region of the TFT and its electrode wiring (gate electrode wiring, drain electrode wiring) through the interlayer insulating films 22 and 24. Therefore, the electric field due to the TFT and the electrode wiring can be prevented from leaking to the liquid crystal layer 40 and adversely affecting the alignment of the liquid crystal molecules, and the planarity of the surface of the pixel electrode 26 can be improved by the planarization interlayer insulating film 24. Therefore, it is possible to prevent the disorder of the alignment of the liquid crystal molecules due to the unevenness of the surface of the pixel electrode 26. Furthermore, since the configuration can reduce the leakage of electric field due to the TFT and the electrode wiring and the unevenness of the surface of the pixel electrode 26 as described above, in this embodiment, the edge portion of the pixel electrode 26 and the alignment control window 34 The alignment of the liquid crystal molecules is controlled by the electric field effect, and the rubbing process for the vertical alignment film 28 is not necessary.

  As described above, in this embodiment, a polycrystalline silicon TFT capable of forming a channel, a source, and a drain by self-alignment is used as a switching element of the display unit, and the TFT of the display unit is provided around the liquid crystal display unit. A driver made of a polycrystalline silicon TFT having a CMOS structure manufactured by substantially the same process is provided. For this reason, it is possible to improve the yield as a liquid crystal display device by omitting a rubbing step that may adversely affect the polycrystalline silicon TFT in the driver portion where TFTs are densely packed as in this embodiment. .

  In addition, when the pixel electrode 26 is formed so as to cover the TFT and each electrode wiring, for example, in the case of a reflective liquid crystal display device, the aperture ratio is not limited by the TFT or the wiring. It becomes possible to make it high. Even in the case of the transmissive type, the pixel electrode 26 is arranged in an upper layer in the region partitioned by the TFT and the electrode wiring, and the transparent pixel electrode 26 is formed so as to cover the TFT and the electrode wiring. It is possible to achieve the maximum aperture ratio.

  Furthermore, since the distance between the pixel electrode 26 and the liquid crystal layer 40 is shortened by making the pixel electrode 26 above the TFT and each electrode wiring, a driving voltage is efficiently applied to the liquid crystal layer 40 by the pixel electrode 26. It becomes possible to do.

It is a conceptual diagram which shows an example of the plane structure of the active matrix type liquid crystal display device which concerns on this embodiment. It is a figure which shows the schematic cross section along the AA of the liquid crystal display device of FIG.

Explanation of symbols

  10 TFT substrate (first substrate), 12 gate electrode, 13, 14 gate insulating film, 16 source electrode, 18 drain electrode, 20 polycrystalline silicon thin film, 20S source region, 20LS low concentration source region, 20CH channel region, 20D drain Region, 20LD low concentration drain region, 22 interlayer insulating film, 23 implantation stopper, 24 planarization interlayer insulating film (SOG), 26 pixel electrode, 28 vertical alignment film, 30 counter substrate (second substrate), 32 common electrode, 34 Alignment control window, 36 protective film, 38 color filter, 40 liquid crystal layer, 42 liquid crystal molecules.

Claims (6)

A plurality of pixel electrodes provided in a matrix form on a first substrate, a thin film transistor formed to be connected to the corresponding pixel electrode, and an electrode wiring thereof,
Active display is performed by driving, for each pixel electrode, a liquid crystal layer sandwiched between the plurality of pixel electrodes on the first substrate and a common electrode on a second substrate disposed opposite to the first substrate. A matrix type liquid crystal display device,
As the thin film transistor, a polycrystalline silicon thin film transistor using a polycrystalline silicon layer formed at a low temperature in the active layer is used,
Controlling the initial alignment of each liquid crystal molecule of the liquid crystal layer sandwiched between the first and second substrates to be substantially perpendicular to the pixel electrode;
As a liquid crystal material used for the liquid crystal layer, among materials having a molecular structure represented by the following chemical formulas (1) to (6) including fluorine in a side chain,

An active matrix type liquid crystal display device, wherein at least one kind of liquid crystal molecules is selected. The active matrix liquid crystal display device according to claim 1,
The common electrode on the second substrate is provided with an electrode absent portion for controlling the alignment of the liquid crystal as an alignment control window in a predetermined corresponding region facing the pixel electrode, so that the alignment of the liquid crystal molecules from the vertical direction. An active matrix liquid crystal display device, wherein a plurality of regions having different inclination directions are created in each pixel electrode region while being changed. In the active matrix type liquid crystal display device according to claim 1 or 2,
In the first substrate,
A planarized interlayer insulating film is formed so as to cover the thin film transistor formed on the first substrate and its electrode wiring,
An active matrix liquid crystal display device, wherein the plurality of pixel electrodes are respectively formed on the planarization interlayer insulating film. In the active matrix type liquid crystal display device according to claim 1 or 2,
In the first substrate,
A planarization interlayer insulating film is formed so as to cover the thin film transistor formed on the first substrate,
An active matrix liquid crystal display device, wherein the plurality of pixel electrodes are formed on the planarized interlayer insulating film so as to cover at least the formation region of the thin film transistor. The active matrix liquid crystal display device according to claim 2,
The liquid crystal material used for the liquid crystal layer has negative dielectric anisotropy,
The vertical alignment of the liquid crystal layer includes a vertical alignment film formed so as to cover the common electrode and the pixel electrode without performing a rubbing process, the alignment control window provided in the common electrode, and the plurality of the alignment layers. An active matrix liquid crystal display device controlled by a voltage applied to each pixel electrode. In the active matrix type liquid crystal display device according to any one of claims 1 to 5,
An active matrix type liquid crystal display device, wherein a drive circuit comprising thin film transistor groups having substantially the same structure as the polycrystalline silicon thin film transistor is formed in a peripheral portion of the first substrate.

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