JP2006208530A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of obtaining high contrast by suppressing light leakage during black display. <P>SOLUTION: The liquid crystal display device comprises an electrode substrate providing a plurality of pixel electrodes; an opposite substrate arranged oppositely to the electrode substrate and aligned in a substantially parallel direction to alignment processing of the electrode substrate; and a chiral nematic liquid crystal sandwiched between the electrode substrate and the opposite substrate and divided into at least two bend alignment regions in each pixel by an electric field between a pixel electrode and the opposite electrode. The liquid crystal display device arranges a shading layer (auxiliary capacity electrode 20) in at least one of the electrode substrate and the opposite substrate positioned at a boundary of the adjacent vent alignment region in each pixel. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device having excellent moving image display characteristics and a wide viewing angle.

  A liquid crystal display device that mainly displays a moving image such as a television or a multimedia monitor is required to have a faster response characteristic than a liquid crystal display device that mainly displays a still image such as a PC monitor. Several liquid crystal modes using bend alignment or alignment similar to bend alignment have been proposed as liquid crystal modes that realize high-speed response characteristics. In the present specification, the term “bend orientation” includes orientations similar to the bend orientation.

  The bend alignment will be described using the cross-sectional view of the liquid crystal panel shown in FIG. Bend alignment means that the liquid crystal molecules 102 of the liquid crystal layer 101 are aligned in a bow shape as shown in FIG. The liquid crystal layer 101 is sandwiched between a glass substrate 105 on which an alignment film 103 and a transparent electrode 104 are stacked, and the alignment of the liquid crystal molecules 102 is performed depending on the voltage applied between the transparent electrodes 104 formed on the glass substrates 105 on both sides. The degree of bending is controlled. In the bend alignment, since no backflow occurs in the liquid crystal layer 101 in response to a voltage change, a high-speed response characteristic can be obtained in principle. Details are described in Non-Patent Document 1, for example.

  Next, among liquid crystal modes using bend alignment, a liquid crystal mode called OCB (Optically Compensated Bend) mode has both high-speed response characteristics and wide viewing angle characteristics. However, in the OCB mode, since the alignment in the initial alignment state (the alignment state when no voltage is applied) is the splay alignment, a high initialization voltage of 20 V or more is required to obtain the bend alignment necessary for display. There was a problem. Details are described in Non-Patent Document 2, for example.

  Among liquid crystal modes using bend alignment, there is a liquid crystal mode called a DDB (Dual-Domain Bend) mode other than the OCB mode. This DDB mode is a liquid crystal mode having at least two bend alignment regions in one pixel, and does not require a high voltage for obtaining bend alignment in addition to high-speed response characteristics. This is because the initial orientation of the DDB mode is a twist orientation of about 180 degrees, and thus the bend orientation is continuously changed by voltage application. Further, since the DDB mode has at least two symmetrically aligned regions, it has a feature that a viewing angle characteristic with good symmetry can be obtained. Details are described in Patent Document 1.

JP 2003-66491 A SHINYA ONDA, 2 others, "Mechanism of Fast Response and Recover in Bend Alignment Cell", Mol. Cryst. Liq. Cryst., 1999, Vol. 331, p.383-389 K. Sueoka, 2 others, "Initialization of Optically Compensated Bend-Mode LCDs", AM-LCD / IDW '96 Proceedings, p.133-136

  As described in the background art, the liquid crystal display device using the DDB mode has good response characteristics and high viewing angle symmetry. However, a liquid crystal display device using the DDB mode has a problem in that light leakage occurs when black display is performed, sufficiently low black luminance (black transmittance) cannot be obtained, and white / black contrast is low. It was.

  Accordingly, the present invention has been made to solve the above-described problems, and an object thereof is to provide a liquid crystal display device capable of suppressing light leakage during black display and obtaining high contrast.

  The solution according to the present invention includes an electrode substrate provided with a plurality of pixel electrodes, and a counter electrode disposed opposite to the electrode substrate, and is aligned in a substantially antiparallel direction with respect to the alignment processing of the electrode substrate. And a chiral nematic liquid crystal sandwiched between the electrode substrate and the counter substrate and divided into at least two bend alignment regions in each pixel by an electric field between the pixel electrode and the counter electrode, In each pixel, a light shielding layer is disposed on at least one of the electrode substrate and the counter substrate positioned at the boundary between adjacent bend alignment regions.

  In the liquid crystal display device according to the present invention, since the light shielding layer is disposed on at least one of the electrode substrate and the counter substrate located at the boundary between the adjacent bend alignment regions in each pixel, light leakage during display is prevented. It has the effect of suppressing and obtaining high contrast.

(Embodiment 1)
First, before describing the liquid crystal display device according to the present embodiment, the liquid crystal alignment in the DDB mode will be described. FIG. 1A is a perspective view schematically showing a cross section of a DDB mode liquid crystal panel 12 in an initial alignment state. FIG. 1B is a perspective view schematically showing a cross section of the DDB mode liquid crystal panel 12 in the alignment state during display. In the liquid crystal panel 12 shown in FIG. 1A, the liquid crystal layer 1 is sandwiched between the glass substrate 5 on which the alignment film 3 and the transparent electrode 4 are laminated, and is applied between the transparent electrodes 4 formed on the glass substrates 5 on both sides. A configuration is shown in which the orientation of the liquid crystal molecules 2 is controlled by the level of the applied voltage. In the DDB mode, a nematic liquid crystal material (hereinafter, also referred to as chiral nematic liquid crystal) in which the surfaces of the alignment films 3 on both glass substrates 5 are aligned in an antiparallel direction (opposite direction) and has chirality in the liquid crystal layer 1 is used. .

  As shown in FIG. 1A, the initial alignment state in the DDB mode is a twist alignment of 180 degrees including a spray alignment component. In the drawing, the alignment treatment direction 6 on the surface of the alignment film 3 is indicated by an arrow. A characteristic of the initial alignment state is that the liquid crystal molecules 2 near the center of the liquid crystal layer 1 are horizontal to the surface of the glass substrate 5. Note that the liquid crystal material used in the DDB mode is p-type liquid crystal with positive dielectric anisotropy.

  As shown in FIG. 1B, the alignment state during display in the DDB mode is composed of two bend alignment regions in which the bending direction of the bend alignment is opposite between the region A and the region B. This is because the liquid crystal molecules 2 near the center of the liquid crystal layer 1 are horizontal, so that when the liquid crystal molecules 2 rise from the left side of FIG. When the right side of 1 (b) rises, a bent orientation such as region B is formed. In the DDB mode, unlike the bend alignment used in the OCB mode, the center of the liquid crystal layer 1 in each region A and B is affected by the chiral nematic liquid crystal (in the case of FIG. 1B, counterclockwise from top to bottom). The nearby liquid crystal molecules 2 are not perpendicular to the surface of the glass substrate 5 when a voltage is applied, but are tilted in the tilt direction 7 indicated by the arrows.

  In order to divide the alignment regions as in the regions A and B, a method using an oblique electric field generated by a long slit opened in the transparent electrode 4 or a protrusion structure provided on the transparent electrode 4, or an alignment film There is a method in which a difference in roughness is provided on the surface of No. 3 and a difference in pretilt angle (rising angle at the interface) generated by the difference is used.

  Next, a DDB mode in which a slit is provided in the transparent electrode 4 to generate an oblique electric field will be described. FIG. 2 is a cross-sectional view of a liquid crystal panel in which a slit 8 is provided in the transparent electrode 4. Although the alignment film 3 is not shown in the cross-sectional view shown in FIG. 2, the alignment film 3 is formed on the innermost surface of each glass substrate 5. In the liquid crystal panel of FIG. 2, slits 8 are alternately provided in the upper transparent electrode 4, and slits 9 are alternately provided in the lower transparent electrode 4. Each of the slits 8 and 9 has a long shape in a direction perpendicular to the paper surface. When a voltage is applied between the transparent electrodes 4 of such a liquid crystal panel, an oblique electric field 10 is generated at the slits 8 and 9. The oblique electric field 10 controls the rising direction of the liquid crystal molecules 2 located near the center of the liquid crystal layer 1 to form at least two bent alignment regions in one pixel.

  Next, a DDB mode in which a projection structure is provided on the transparent electrode 4 to generate an oblique electric field will be described. FIG. 3 is a cross-sectional view of a liquid crystal panel in which a protruding structure 11 is provided with a dielectric material instead of the slit 8 provided in the upper transparent electrode 4 shown in FIG. In the liquid crystal panel of FIG. 3, the protruding structure 11 has a long bowl shape in a direction perpendicular to the paper surface. For the protrusion structure 11, a dielectric material having a relative dielectric constant smaller than that of the liquid crystal material is used. Specifically, since the dielectric constant of the liquid crystal material is about 4 to 15, for example, the protruding structure 11 is formed of a silicon oxide film (relative dielectric constant of about 3) or the like. Even in the liquid crystal panel shown in FIG. 3, an oblique electric field 10 is generated in the protruding structure 11 when a voltage is applied.

  Next, the configuration and display principle of the optical film in the DDB mode liquid crystal display device will be described. In the DDB mode, when performing a normally white operation in which white display is performed on the low voltage side and black display is performed on the high voltage side, the residual phase difference of the liquid crystal layer 1 is compensated for by the black display voltage (hereinafter also simply referred to as black voltage). In addition, it is necessary to dispose a retardation film on the outside of the glass substrate 5. Furthermore, it is necessary to arrange a polarizing plate outside the retardation film. FIG. 4 shows an example of an optical film configuration in a DDB mode liquid crystal display device. In FIG. 4, a uniaxial film (hereinafter referred to as a plate 13) having a phase difference in the film plane is provided on the outside of the liquid crystal panel 12 shown in FIG.

  The a plate 13 cancels the residual phase difference of the liquid crystal layer 1 that occurs in the alignment treatment direction 6 by arranging the slow axis a in a direction substantially orthogonal to the alignment treatment direction 6 of the liquid crystal. In the liquid crystal device shown in FIG. 4, the a plates 13 are arranged above and below the liquid crystal panel 12, and the sum of the phase differences of the a plates 13 is set to be equal to the residual phase difference of the liquid crystal layer 1. Furthermore, a uniaxial film (hereinafter referred to as “c plate 14”) having a negative phase difference in the thickness direction of the film is disposed outside the a plate 13. Since the c-plate 14 has no phase difference in the film plane, the transmittance at the front of the film is hardly affected, but has a function of suppressing light leakage from an oblique direction. Further, a polarizing plate 15 is disposed outside the c plate 14. Here, the polarizing plate 15 is a linear polarizing plate, and its transmission axis direction b is indicated by an arrow in FIG. The transmission axis direction b of the polarizing plate 15 is arranged so as to be orthogonal to the upper and lower sides of the polarizing plate 15 and at an angle of 45 degrees with the alignment processing direction 6 of the liquid crystal layer 1.

  In the DDB mode liquid crystal display device having the optical film configuration shown in FIG. 4, the white transmittance distribution is as shown in FIG. The numbers in the figure are transmittances (%) normalized using the transmittance at the pixel openings of the liquid crystal display device to which the retardation films (a plate 13 and c plate 14) and the polarizing plate 15 are not attached. It is. In general, liquid crystal display devices require symmetrical viewing angle characteristics in the left-right direction, but the DDB mode has excellent symmetry not only in the left-right direction but also in the up-down direction as shown in FIG. This is because, as shown in FIG. 1B, the DDB mode has two bent alignment regions, so that the bending direction of the bend alignment and the direction of the inclination of the liquid crystal molecules 2 near the center of the liquid crystal layer 1 due to the twist component. This is because the alignment state of the liquid crystal molecules 2 is compensated for each other.

  However, the liquid crystal display device in the DDB mode has a problem that the black transmittance (black luminance) increases and the white / black contrast deteriorates during black display. By analyzing the DDB mode liquid crystal display device for this problem, the DDB mode liquid crystal display device leaks light at the boundary between adjacent vent alignment regions, that is, the portion where the slit 8 or the protrusion structure 11 is disposed. I found a phenomenon. Due to this phenomenon, it has been found that in the DDB mode liquid crystal display device, the black transmittance (black luminance) increases and the white / black contrast deteriorates. This is because a predetermined vertical electric field (an electric field applied in the thickness direction of the liquid crystal layer 1) is not applied to the liquid crystal layer 1 at the position where the slit 8 or the protrusion structure 11 is provided. In addition, in the case of the protrusion structure 11, the fact that the alignment state on the side wall surface of the protrusion is different from the predetermined alignment state is also affected.

  In the liquid crystal display device according to the present embodiment, in order to solve the above problems, a light shielding layer is provided in a portion where light leakage occurs. For example, in the case of a liquid crystal display device that performs alignment division by slits 8 and 9 provided on both glass substrates 5, light leakage at the slit 8 is blocked by using an auxiliary capacitance electrode.

  FIG. 6A is a perspective view of the electrode substrate of the liquid crystal display device according to the present embodiment. FIG. 6B is a perspective view of the counter substrate of the liquid crystal display device according to the present embodiment. FIG. 6C is a cross-sectional view of the liquid crystal display device according to this embodiment. The cross-sectional view of FIG. 6C is a cross-section taken along the line CD shown in FIGS. 6A and 6B. 6A to 6C show a unit structure corresponding to one pixel of the liquid crystal display device. In an actual liquid crystal display device, similar structures are arranged in a matrix in the vertical direction and the horizontal direction. Yes.

  The lower substrate of the liquid crystal panel shown in FIG. 2 corresponds to the electrode substrate shown in FIG. The electrode substrate has a gate wiring 17 arranged in one direction on the transparent substrate 16 such as glass (in the case of FIG. 6A, the lateral direction). A gate electrode 18 is connected to the gate wiring 17. A storage capacitor line 19 is arranged in the same direction as the gate line 17 and a storage capacitor electrode 20 is connected thereto. The gate wiring 17 and the auxiliary capacitance wiring 19 are covered with the first insulating film 21, and the signal wiring 22 is on the insulating film 21 in a direction different from the direction of the gate wiring 17 and the auxiliary capacitance wiring 19 (FIG. 6A). In the case of (vertical direction).

  A source electrode 23 is connected to the signal wiring 22. Note that the gate wiring 17 and the auxiliary capacitance wiring 19 and the signal wiring 22 are electrically insulated because they are formed in different layers with the insulating layer 21 in between. A TFT (Thin Film Transistor) section 25 serving as a switching element is constituted by the gate electrode 17, the source electrode 23, the drain electrode 24, the insulating film 21, a semiconductor layer (not shown), and the like. An upper layer such as the signal wiring 22 is covered with a second insulating film 26.

  A contact hole 27 is provided in the second insulating film 26 on the drain electrode 24, and the drain electrode 24 and the pixel electrode 28 formed in the upper layer of the second insulating film 26 are electrically connected. . The pixel electrode 28 is made of a transparent conductive material such as ITO (Indium Tin Oxide). An alignment film (not shown) such as polyimide or polyamide is further formed on the electrode substrate having the above configuration, and the surface thereof is subjected to a rubbing process or the like in a specific alignment process direction 29. On the electrode substrate side, since the periphery of the pixel electrode 28 functions as the slit 9 shown in FIG. 2, it is not necessary to dispose the slit 9 in the pixel electrode 28.

  Next, the upper substrate 5 of the liquid crystal panel shown in FIG. 2 corresponds to the counter substrate shown in FIG. As the counter substrate, a black matrix (hereinafter also referred to as BM) 31 for light shielding is disposed on a transparent substrate 30 such as glass and is divided into pixels. Color material layers 32 of red, green, blue, etc. are formed in the pixel. An overcoat layer 33 made of a transparent organic film is provided above the color material layer 32, and a counter electrode 34 made of a transparent conductive material is further provided thereon. However, in the case of a monochrome liquid crystal display device or the like, the color material layer 32 and the overcoat layer 33 may not be provided.

  A slit 35 is formed in the counter electrode 34 in the vertical direction in the center of the pixel. The slit 35 corresponds to the slit 8 shown in FIG. Similarly to the electrode substrate, an alignment film (not shown) such as polyimide or polyamide is formed on the counter substrate having the above configuration, and the surface thereof has an alignment treatment direction 36 opposite to the alignment treatment direction 29 of the electrode substrate. Is subjected to orientation treatment.

  In the present embodiment, as shown in FIG. 6A, the auxiliary capacitance electrode 20 is disposed at a position on the electrode substrate facing the slit 35 provided in the counter substrate. Therefore, it is possible to block light leakage at the slit 35 that occurs during black display by the auxiliary capacitance electrode 20. Therefore, in the liquid crystal display device according to the present embodiment, display characteristics with high contrast can be realized. The auxiliary capacitance electrode 20 is not a transparent electrode.

  Next, a method for manufacturing the liquid crystal display device according to the present embodiment will be described. First, a method for manufacturing an electrode substrate will be described. A metal chromium film having a thickness of 300 nm is formed on a glass transparent substrate 16, and the gate wiring 17, the gate electrode 18, the auxiliary capacitance wiring 19, and the auxiliary capacitance electrode 20 are formed by photolithography. Next, a 400 nm silicon nitride film is formed as the first insulating film 21 on the gate wiring 17 and the like. Subsequently, an amorphous silicon film is formed with a thickness of 100 nm and a doped amorphous silicon film is formed with a thickness of 100 nm on the first insulating film 21, and the TFT portion 25 is formed by photolithography.

  Again, a 300 nm metallic chromium film is formed on the doped amorphous silicon film or the first insulating film 21, and the signal wiring 22, source electrode 23, and drain electrode 24 are formed by photolithography. Next, a 400 nm silicon nitride film is formed as the second insulating film 26 on the signal wiring 22 and the like, and a contact hole 27 is formed by photolithography. Subsequently, an ITO film having a thickness of 100 nm is formed on the second insulating film 26, and the pixel electrode 28 is formed by photolithography.

  Next, a method for manufacturing the counter substrate will be described. A metallic chromium film is formed to a thickness of 300 nm on a glass transparent substrate 30, and BM31 is formed by photolithography. On the transparent substrate 30 after the BM 31 is formed, the red, green, and blue color material layers 32 are repeatedly formed by film formation and photolithography. Thereafter, an overcoat layer 33 is formed on the color material layer 32. Further, an ITO film having a thickness of 100 nm is formed on the overcoat layer 33, and a slit 35 is formed at the center of the pixel by photolithography.

  A method for manufacturing a liquid crystal panel using the electrode substrate and the counter substrate manufactured as described above will be described. An alignment film (Optomer (registered trademark) AL3046 manufactured by JSR) is formed on the electrode substrate and the counter substrate to a thickness of about 80 nm, and the alignment treatment direction 29 shown in FIGS. 6A and 6B is used using a roller rubbing apparatus. , 36 is rubbed. Next, a resin spacer (Micropearl (registered trademark) manufactured by Sekisui Chemical Co., Ltd.) is sprayed on the counter substrate side.

  On the other hand, a sealing agent is applied to the periphery of the transparent substrate 16 on the electrode substrate side. Subsequently, the electrode substrate and the counter substrate are overlapped in a predetermined direction, and bonded together by thermocompression bonding. The gap between the electrode substrate and the counter substrate (hereinafter referred to as the panel gap) is adjusted to 7 μm. Thereafter, a liquid crystal material is injected from the opening of the sealant.

  In the DDB mode used in the liquid crystal display device according to the present embodiment, a liquid crystal display that uses a change in phase difference of a liquid crystal layer between a state in which liquid crystal molecules are horizontally aligned on the substrate surface and a state in which the liquid crystal molecules are raised when a voltage is applied. Mode (for example, Twisted Nematic mode) or a liquid crystal display mode (for example, Vertical mode) that uses the phase difference change of the liquid crystal layer between the state in which liquid crystal molecules are aligned perpendicular to the substrate surface and the state in which the liquid crystal molecules are laid down when voltage is applied Unlike the alignment mode), since the change in the liquid crystal alignment state between white display and black display is small, it is desirable to use a liquid crystal material having a large birefringence in order to obtain a sufficient transmittance change. In the DDB mode, the chiral pitch p of the liquid crystal material needs to satisfy the relationship (4d) / 3 <p <4d in order to twist the initial alignment. Here, d indicates a panel gap.

  Next, Table 1 shows the characteristics of the liquid crystal material used in the liquid crystal display device according to this embodiment.

  After injecting the liquid crystal material shown in Table 1 into the liquid crystal panel, the opening (liquid crystal injection port) of the sealing agent is sealed using an ultraviolet curable resin. After the liquid crystal panel is manufactured, a driving circuit is mounted on the gate wiring 17, the signal wiring 22, the counter electrode 34, and the like so that a predetermined voltage can be applied to each electrode.

  After mounting the drive circuit, a retardation film or polarizing plate having the characteristics shown in Table 2 is attached to the liquid crystal panel using an adhesive film or the like. The directions such as the transmission axis and the slow axis shown in Table 2 indicate counterclockwise angles when the right hand is 0 degree when the liquid crystal display device is viewed from the front. That is, the alignment processing directions 29 and 36 shown in FIGS. 6A and 6B correspond to 90 degrees and 270 degrees, respectively. The phase difference shown in Table 2 is a value at a wavelength of 550 nm.

  A liquid crystal display device is manufactured by disposing the liquid crystal panel 12 (having a retardation film or the like attached thereto) on the surface light source such as a backlight.

  FIG. 7 shows electro-optical characteristics of the liquid crystal display device according to this embodiment. FIG. 7 shows applied voltage-transmittance characteristics in front of the liquid crystal display device, where the horizontal axis represents the applied voltage [V] and the vertical axis represents the transmittance [%]. Here, the applied voltage indicates a voltage applied between the pixel electrode 28 and the counter electrode 34. The transmittance is normalized by the transmittance at the opening of the liquid crystal panel to which no retardation film or the like is attached. In the liquid crystal display device according to the present embodiment, the black voltage is set to 6.3 V and the white voltage is set to 2.5 V. As shown in FIG. 7, in the liquid crystal display device according to the present embodiment, it can be seen that the transmittance during black display is kept low. Therefore, the white / black contrast is approximately 500.

  In the liquid crystal display device according to the present embodiment, when black display is performed, when the micro luminance distribution in the pixel is observed with a microscope, the position where the slit 35 is located on the counter substrate 28 is covered with the auxiliary capacitance electrode 20. No light leakage was observed. Note that the shapes of the auxiliary capacitance electrode 20 and the auxiliary capacitance wiring 19 are not limited to the shapes shown in FIG. In the liquid crystal display device according to the present invention, it may be a position that overlaps with the slit 35 of the counter substrate 28, and for example, may have a shape such as the auxiliary capacitance electrode 20 and the auxiliary capacitance wiring 19 shown in FIG. 8.

  As described above, in the liquid crystal display device according to the present embodiment, the auxiliary capacitance electrode 20 that is a light shielding layer is provided on at least one of the electrode substrate and the counter substrate that are located at the boundary between adjacent bend alignment regions in each pixel. Since it is arranged, light leakage during black display can be suppressed and high contrast can be obtained. Further, in the liquid crystal display device according to the present embodiment, since the light shielding layer is the auxiliary capacitance electrode 20, the opening rate of the pixels is not lowered as compared with the case where both the light shielding layer and the auxiliary capacitance electrode 20 are provided. High contrast can be obtained.

(Embodiment 2)
In the first embodiment, light leakage at the slit 35 is blocked by the auxiliary capacitance electrode 20, but in this embodiment, a configuration in which a light shielding layer is provided in place of the auxiliary capacitance electrode 20 will be described.

  FIG. 9A is a perspective view showing the configuration of the electrode substrate of the liquid crystal display device according to this embodiment. FIG. 9B is a cross-sectional view taken along line CD of the electrode substrate of the liquid crystal display device according to this embodiment. Note that the structure on the counter substrate is the same as that in FIG. 6B described in Embodiment Mode 1, and thus detailed description is omitted in this embodiment mode. 9A and 9B, the same components as those in FIGS. 6A and 6C are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the liquid crystal display device according to the present embodiment, as shown in FIG. 9A, a vertically long light shielding layer 37 is disposed at a position facing the slit 35 on the counter substrate side to block light leakage at the slit 35. . On the other hand, unlike the first embodiment, the auxiliary capacitance electrode 20 is arranged around the pixel electrode 28 and connected to the auxiliary capacitance wiring 19 as shown in FIG. 9A. The light shielding layer 37 is formed on the transparent substrate 16 as shown in FIG. The auxiliary capacitance electrode 20 and the auxiliary capacitance wiring 19 are also formed on the same transparent substrate 16, but are not electrically connected to the light shielding layer 37.

  Since the method for manufacturing the electrode substrate is basically the same as that in the first embodiment, detailed description thereof is omitted in the present embodiment. However, the light shielding layer 37 is formed simultaneously with the gate wiring 17, the auxiliary capacitance electrode 20, the auxiliary capacitance wiring 19, and the like. Note that the light shielding layer 37 is made of a light shielding material such as metal chrome instead of a transparent material because of the necessity of light shielding.

  As described above, in the liquid crystal display device according to the present embodiment, since the light shielding layer 37 is provided on the electrode substrate and simultaneously with the gate wiring 17 and the like formed on the electrode substrate, the light shielding layer 37 is provided. In addition, it is not necessary to add a new process, and the manufacturing cost can be reduced and high contrast can be obtained.

  In the present embodiment, the case where the light shielding layer 37 is formed simultaneously with the gate wiring 17 and the like has been described. However, the present invention is not limited to this, and may be formed simultaneously with the signal wiring 22 and the like. Even in this case, the liquid crystal display device can reduce the manufacturing cost and obtain high contrast.

(Embodiment 3)
In the liquid crystal display device according to the first and second embodiments, the light shielding layer is arranged on the electrode substrate side. However, in the liquid crystal display device 3 according to the present embodiment, a configuration in which the light shielding layer is disposed on the counter substrate side instead of the light shielding layer on the electrode substrate side will be described.

  FIG. 10A is a perspective view showing the configuration of the electrode substrate of the liquid crystal display device according to the present embodiment. FIG. 10B is a perspective view showing the configuration of the counter substrate of the liquid crystal display device according to the present embodiment. FIG. 10C is a cross-sectional view taken along line CD of the liquid crystal display device according to this embodiment. 10A to 10C, the same components as those in FIGS. 6A to 6C are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the liquid crystal display device according to the present embodiment, as shown in FIG. 10B, a light shielding layer 38 is disposed at the center of the pixel so as to overlap the slit 35 of the counter substrate. On the other hand, it is not necessary to provide the auxiliary capacitance electrode 20 or the light shielding layer 37 in the center of the pixel on the electrode substrate side. As shown in FIGS. 10B and 10C, the light shielding layer 38 is integrally formed by changing the shape of the BM 31 formed around the pixel. Therefore, the light shielding layer 38 is the same layer as the BM 31 formed around the pixel and can be formed in the same process.

  As described above, in the liquid crystal display device according to the present embodiment, the light shielding layer 38 is provided on the counter substrate and is formed simultaneously with the black matrix formed on the counter substrate. Therefore, it is not necessary to add a process to the above, and the manufacturing cost can be reduced and high contrast can be obtained. Further, in the liquid crystal display device according to the present embodiment, since the light shielding layer 38 and the slit 35 are formed on the same counter substrate, the liquid crystal display device is affected by a positional deviation that occurs when the electrode substrate and the counter substrate are overlapped. The light leakage can be suppressed with high accuracy. Further, since the positional deviation between the light shielding layer 38 and the slit 35 does not occur, it is not necessary to consider the margin due to the positional deviation in the shape of the light shielding layer 38, and the light shielding layer 38 can be made smaller. Therefore, in the liquid crystal display device according to this embodiment, the aperture ratio of the pixel can be increased as compared with other embodiments.

  In the first to third embodiments described above, the case where the alignment division is performed by arranging the slit on the counter substrate side is described, but the present invention is not limited to this, and the protrusion structure is arranged on the counter substrate side. Even when orientation division is performed, high contrast can be obtained by similarly disposing the light shielding layer on the electrode substrate or the counter substrate.

  In the first to third embodiments described above, as shown in FIGS. 6 (a) and 6 (b), the alignment treatment directions 29 and 36 are the vertical directions in the figure, and two bent alignment regions are provided on the left and right. The case where it is formed has been described. However, the present invention is not limited to this, and the alignment treatment directions 29 and 36 are the left and right directions in the drawing as shown in FIGS. 11A and 11B, and two bent alignment regions are formed on the top and bottom. Even in such a case, a high contrast can be obtained by providing the auxiliary capacitance electrode 20 as a light shielding layer in the lateral direction.

  FIG. 11A is a perspective view showing the configuration of the electrode substrate in which the auxiliary capacitance electrode 20 is arranged in the horizontal direction. FIG. 11B is a perspective view showing the configuration of the counter substrate provided with slits 35 in the lateral direction. 11A and 11B, the same components as those in FIGS. 6A and 6B are denoted by the same reference numerals, and detailed description thereof is omitted.

(Comparative example)
As a comparative example, a liquid crystal display device in which the light shielding layer is not disposed on either the electrode substrate side or the counter substrate side will be described. The liquid crystal display device can be formed by bonding an electrode substrate having a structure illustrated in FIG. 10A and a counter substrate having a structure illustrated in FIG. With respect to the liquid crystal display device, the state of pixels during black display was observed with a microscope, and light leakage was observed at the slit 35 on the counter substrate side. Further, when the contrast of the liquid crystal display device was measured, it was about 50.

It is a figure explaining the structure of the liquid crystal display device used as the premise of this invention. It is sectional drawing of the liquid crystal display device used as the premise of this invention. It is sectional drawing of the liquid crystal display device used as the premise of this invention. It is a figure explaining the structure of the liquid crystal display device used as the premise of this invention. It is a figure explaining the optical characteristic of the liquid crystal display device used as the premise of this invention. It is a figure explaining the structure of the liquid crystal display device which concerns on Embodiment 1 of this invention. It is a figure explaining the optical characteristic of the liquid crystal display device which concerns on Embodiment 1 of this invention. It is a figure explaining the structure of the liquid crystal display device which concerns on Embodiment 1 of this invention. It is a figure explaining the structure of the liquid crystal display device which concerns on Embodiment 2 of this invention. It is a figure explaining the structure of the liquid crystal display device which concerns on Embodiment 3 of this invention. It is a figure explaining the structure of the liquid crystal display device which concerns on the modification of this invention. It is sectional drawing explaining the structure of the liquid crystal display device of bent orientation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal layer, 2 Liquid crystal molecule, 3 Orientation film, 4 Transparent electrode, 5 Glass substrate, 6, 29, 36 Orientation process direction, 7 Inclination direction, 8, 9, 35 Slit, 10 Diagonal electric field, 11 Protrusion structure, 12 Liquid crystal Panel, 13 a plate, 14 c plate, 15 polarizing plate, 16, 30 transparent substrate, 17 gate wiring, 18 gate electrode, 19 auxiliary capacitance wiring, 20 auxiliary capacitance electrode, 21, 26 insulating film, 22 signal wiring, 23 source Electrode, 24 drain electrode, 25 TFT section, 27 contact hole, 28 pixel electrode, 31 black matrix, 32 color material layer, 33 overcoat layer, 34 counter electrode, 37, 38 light shielding layer, 101 liquid crystal layer, 102 liquid crystal molecule, 103 alignment film, 104 transparent electrode, 105 glass substrate.

Claims (4)

An electrode substrate provided with a plurality of pixel electrodes;
A counter electrode disposed opposite to the electrode substrate, and a counter substrate oriented in a substantially antiparallel direction with respect to the alignment treatment of the electrode substrate;
A chiral nematic liquid crystal sandwiched between the electrode substrate and the counter substrate and divided into at least two bend alignment regions in each pixel by an electric field between the pixel electrode and the counter electrode;
A liquid crystal display device, wherein a light shielding layer is arranged on at least one of the electrode substrate and the counter substrate located at a boundary between adjacent bend alignment regions in each pixel. The liquid crystal display device according to claim 1,
The liquid crystal display device, wherein the light shielding layer is formed on the electrode substrate and simultaneously with the wiring formed on the electrode substrate. The liquid crystal display device according to claim 2,
The liquid crystal display device, wherein the light shielding layer is an auxiliary capacitance electrode formed on the electrode substrate. The liquid crystal display device according to claim 1,
The liquid crystal display device, wherein the light shielding layer is provided on the counter substrate and is formed simultaneously with a black matrix formed on the counter substrate.

Images