JP2005141086A - Liquid crystal display and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transflective liquid crystal display device of a normally black mode, in which the optical rotation compensation of of a liquid crystal layer can be made by the phase difference layer formed in the inner part of a cell, and to provide its manufacturing method. <P>SOLUTION: The liquid crystal layer 30 is made to be twisted for taking a large margin of the gap of the translucent liquid crystal display of the normally black mode. Liquid crystal molecules in a phase difference layer 22, formed in the inner part of the cell and consisting of a liquid crystal polymer, are made to be twisted for compensating the optical rotational properties, when the liquid crystal layer 30 is twisted. Especially, the liquid crystal molecules in the phase difference layer 22 are made to be twisted, preferably in the direction reverse to the twisted direction of the liquid crystal layer 30 for compensating the optical rotation properties of the liquid crystal layer 30. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device and a manufacturing method thereof, and more particularly, to a transflective liquid crystal display device having both a reflective portion and a transmissive portion and a manufacturing method thereof.

  Conventionally, as a display for a personal computer, a transmissive liquid crystal display that performs display using a backlight has been mainstream, but in recent years, a display for a mobile electronic device such as a PDA (Personal Digital Assistant) or a mobile phone is used. Reflecting liquid crystal display devices capable of reducing power consumption as compared with transmissive liquid crystal display devices have attracted attention as the demand for such devices has increased rapidly. This reflection type liquid crystal display device performs display by reflecting incident light from the outside with a reflection plate. Since a backlight is not required, the power consumption is saved, and the transmission type liquid crystal display device is reduced. There is an advantage that the electronic device can be driven for a long time as compared with the case where it is adopted.

  Since the reflective liquid crystal display device uses ambient light to display, assuming that it is used in dark conditions, install a front light on the display surface side of the panel so that light enters from the front light. Have been proposed. However, if the front light is installed on the display surface side, there is a disadvantage that the reflectance and contrast are lowered and the image quality is impaired.

  In order to solve this problem, a transflective liquid crystal display device has been developed in which a transmissive portion is provided in a part of a reflection plate of a pixel portion, and a reflective type and a transmissive type coexist (Patent Documents 1 and 2). Etc.). In this method, since a backlight is installed on the opposite side of the display surface, good visibility can be obtained in both dark and bright areas without impairing the image quality as a reflection type, and high image quality. Can be realized.

FIG. 11 is a diagram showing a schematic configuration of a conventional normally white mode transflective liquid crystal display device.
A conventional transflective liquid crystal display device is formed on one main surface side of the first substrate 110 with a reflective electrode 112 formed of a material having high reflectivity through an interlayer film 111 and a material having high transmittance. The λ / 4 plate 114, the λ / 2 plate 115, and the polarizing plate 116 are stacked in this order on the other main surface side of the first substrate 110.

  In addition, the liquid crystal display device includes a counter electrode 121 on one main surface of the second substrate 120 facing the first substrate 110. Further, a λ / 4 plate 122, a λ / 2 plate 123, and a polarizing plate 124 are laminated in this order on the other main surface side of the substrate 120. A liquid crystal layer 130 made of a liquid crystal material is provided between the reflective electrode 112 and the transparent electrode 113 and the counter electrode 121.

  In the liquid crystal display device shown in FIG. 11, in order to reliably suppress the influence of wavelength dispersion and realize a good black display, a wideband λ / 4 plate combining a λ / 4 plate and a λ / 2 plate is configured, Since the broadband λ / 4 plates are arranged before and after the liquid crystal panel, it is necessary to use a total of four retardation plates.

As described above, the normally white mode transflective liquid crystal display device has a problem that the number of retardation plates increases and the cost increases. Therefore, recently, a normally black mode transflective liquid crystal display device in which the number of retardation plates can be reduced from four to one has been studied. In a normally black mode liquid crystal display device, if a single λ / 2 plate is provided on the opposite side of the liquid crystal layer, a normally black mode display is possible for both reflection and transmission.
JP 2000-29010 A JP 2000-35570 A

  In the normally black mode transflective liquid crystal display device, the liquid crystal layer is designed so as to function as a λ / 4 plate, and black display is performed as a broadband λ / 4 plate in combination with a λ / 2 retardation plate. In the normally black mode, black display is performed in a state where the voltage to the liquid crystal layer is OFF and the liquid crystal molecules are parallel to the substrate. Therefore, in order to obtain a good black display, there is a problem that the margin with respect to the cell gap is small as compared with the normally white mode.

  One method for solving the cell gap problem is to twist the liquid crystal layer. This increases the gap margin. However, when the liquid crystal layer is twisted, the phase difference is not uniaxial but effectively biaxial. Also, since there is an optical rotation component, when compensating for the biaxial liquid crystal layer, if it is attempted to compensate with a uniaxial retardation plate, the viewing angle is poor and sufficient compensation cannot be achieved. For this reason, a biaxial retardation plate is required. However, the biaxial retardation plate has a problem in that the cost increases as compared with the uniaxial one.

  In the normally black mode, when the voltage is OFF, two retardation plates are stacked to increase the bandwidth and suppress the influence of chromatic dispersion. However, when a voltage is applied to bring the liquid crystal layer into a white state, the liquid crystal layer loses its function as a retardation plate, so that the retardation plate becomes a single layer and is affected by wavelength dispersion. Normally, the phase difference value by the phase difference plate is adjusted to the wavelength range of the center of the light, so when applying a voltage and displaying white, the transmittance of the green light at the center increases, resulting in a greenish color. There is a problem of becoming.

  In addition, the liquid crystal molecules of the liquid crystal layer are tilted in one direction with a pretilt angle. However, because of the pretilt, there is an effect on the viewing angle, although not as much as in the normally white mode.

  By the way, since the film-like retardation plate is expensive and has a thickness of several tens of μm, this thickness is also a problem for portable products that are required to be thin.

  The present invention has been made in view of the above circumstances, and its purpose is to compensate for the optical rotation of the liquid crystal layer by a retardation layer formed inside the cell in a normally black mode transflective liquid crystal display device. An object of the present invention is to provide a liquid crystal display device capable of performing optical compensation such as solving the coloring problem of white display and compensating for the viewing angle, and a method for manufacturing the same.

  More specifically, the first object of the present invention is to provide a normally black mode transflective liquid crystal display device in which the optical rotation of the liquid crystal layer can be compensated by the retardation layer formed inside the cell. And providing a manufacturing method thereof.

  More specifically, the second object of the present invention is to provide a normally black mode transflective liquid crystal display device in which a liquid crystal display capable of preventing a coloring phenomenon in white display by a retardation layer formed inside the cell. It is to provide an apparatus and a method for manufacturing the same.

  More specifically, a third object of the present invention is to provide a normally black mode transflective liquid crystal display device that can compensate the viewing angle by a retardation layer formed inside the cell, and its manufacture. It is to provide a method.

  In order to achieve the first object, the liquid crystal display device of the present invention is provided with a first reflecting portion and a transmissive portion, and displays black when the applied voltage to the liquid crystal layer is in a low voltage state and in a high voltage state. A liquid crystal display device for displaying white, wherein a pair of substrates provided with the reflection portion and the transmission portion, the liquid crystal layer sandwiched between the pair of substrates and having a twist arrangement in which liquid crystal molecules are twisted, and The liquid crystal layer is formed between any one of a pair of substrates and the liquid crystal layer, and includes a retardation layer having a twist arrangement in which liquid crystal molecules in the liquid crystal polymer are twisted.

In the above-described liquid crystal display device of the present invention, the retardation layer is formed of a liquid crystal polymer between any one of the pair of substrates and the liquid crystal layer, and has a twist alignment in which the liquid crystal molecules in the liquid crystal polymer are twisted. Is forming.
Therefore, the optical rotation of the liquid crystal layer due to the twist alignment of the liquid crystal molecules is offset by the optical rotation of the retardation layer having a twist alignment in which the liquid crystal molecules in the liquid crystal polymer are twisted.

  In order to achieve the second object, a liquid crystal display device of the present invention includes a pixel provided with a reflective portion and a transmissive portion, and a voltage applied to a liquid crystal layer sandwiched between a pair of substrates is in a low voltage state. A liquid crystal display device that displays black in a high voltage state and displays white in a high voltage state, wherein a wavelength region of light formed between any one of the pair of substrates and the liquid crystal layer is a pixel A plurality of types of color filters that differ from each other, and formed between any one of the pair of substrates and the liquid crystal layer, are made of a liquid crystal polymer, and match the wavelength region of light that the color filter transmits. And a retardation layer whose retardation value is adjusted for each pixel.

In the liquid crystal display device of the present invention, the phase difference due to the liquid crystal layer disappears during white display when the voltage applied to the liquid crystal layer is in a high voltage state, and there is only one phase difference layer.
In the liquid crystal display device of the present invention, the retardation value of the retardation layer is adjusted for each pixel in accordance with the wavelength region of the light transmitted through the color filter. It is suppressed.

  In order to achieve the above third object, the liquid crystal display device of the present invention is provided with a reflective portion and a transmissive portion, and displays black when the applied voltage to the liquid crystal layer is in a low voltage state and displays white in a high voltage state. A liquid crystal display device, comprising: a pair of substrates provided with the reflection portion and the transmission portion; and the liquid crystal layer sandwiched between the pair of substrates and having liquid crystal molecules arranged in a predetermined direction with respect to the substrate surface And a liquid crystal polymer formed between any one of the pair of substrates and the liquid crystal layer, wherein the liquid crystal molecules in the liquid crystal polymer are in the predetermined direction with respect to the substrate surface. And a retardation layer arranged to be inclined in the opposite direction.

In the above-described liquid crystal display device of the present invention, the retardation layer formed between any one of the pair of substrates and the liquid crystal layer is made of a liquid crystal polymer, and the liquid crystal molecules in the liquid crystal polymer are They are arranged in a tilted direction opposite to the predetermined direction with respect to the substrate surface.
Therefore, the influence on the viewing angle due to the liquid crystal molecules of the liquid crystal layer being arranged in a predetermined direction with respect to the substrate surface is affected by the retardation layer in which the liquid crystal molecules are arranged in a direction opposite to the predetermined direction. Is offset by

  In order to achieve the first object, a method of manufacturing a liquid crystal display device according to the present invention includes a pair of substrates provided with a reflective portion and a transmissive portion, and a liquid crystal layer sandwiched between the pair of substrates. A method for manufacturing a liquid crystal display device that displays black in a low voltage state and displays white in a high voltage state, wherein a UV curable liquid crystal is obtained by adding a chiral agent to one of the pair of substrates. A step of forming a retardation layer made of a liquid crystal polymer having a twist alignment in which liquid crystal molecules are twisted, and the one substrate and the step Forming the liquid crystal layer having a twisted arrangement in which liquid crystal molecules are twisted between the pair of substrates with the other substrate facing each other.

  In the manufacturing method of the liquid crystal display device of the present invention, a retardation layer in which liquid crystal molecules in the liquid crystal polymer are twisted is formed in order to cancel the optical rotation of the liquid crystal layer having twist alignment. For this purpose, by adding a chiral agent to the UV curable liquid crystal, the twist angle of the liquid crystal molecules of the liquid crystal polymer constituting the retardation layer and the rotational direction of twist are controlled. Thereby, a liquid crystal display device in which the optical rotation of the liquid crystal layer is compensated is manufactured.

  In order to achieve the above second object, a method for manufacturing a liquid crystal display device according to the present invention includes a pixel provided with a reflective portion and a transmissive portion, and an applied voltage to a liquid crystal layer sandwiched between a pair of substrates is A method of manufacturing a liquid crystal display device that displays black in a low voltage state and displays white in a high voltage state, wherein a plurality of wavelength regions of light transmitted to one of the pair of substrates are different for each pixel A step of forming a seed color filter, and a phase difference value adjusted for each pixel in accordance with a wavelength region of light which is made of a liquid crystal polymer and is transmitted through the color filter on the one substrate or the other substrate. A step of forming a phase difference layer, and a step of forming the liquid crystal layer between the pair of substrates with the one substrate facing the other substrate.

  In the method for manufacturing a liquid crystal display device according to the present invention, the retardation value is adjusted for each pixel in accordance with the wavelength region of light that is made of a liquid crystal polymer and is transmitted through the color filter on one substrate or the other substrate. By forming the retardation layer, a liquid crystal display device in which the influence of wavelength dispersion is suppressed is manufactured.

  In order to achieve the above third object, the method of manufacturing a liquid crystal display device of the present invention includes a reflective portion and a transmissive portion, and displays black when the applied voltage to the liquid crystal layer is in a low voltage state and in a high voltage state. A method of manufacturing a liquid crystal display device for displaying white, wherein a retardation layer made of a liquid crystal polymer in which liquid crystal molecules are arranged in a predetermined direction with respect to a substrate surface is formed on one of the pair of substrates. And a step of forming a liquid crystal layer in which liquid crystal molecules are arranged in a direction opposite to the predetermined direction with respect to the substrate surface, with the one substrate and the other substrate facing each other.

  In the manufacturing method of the liquid crystal display device of the present invention described above, the direction of inclination of the liquid crystal molecules in the retardation layer made of a liquid crystal polymer is manufactured so that the direction of inclination of the liquid crystal molecules in the liquid crystal layer is reversed. A liquid crystal display device with improved corners is manufactured.

  According to the present invention, in a normally black mode transflective liquid crystal display device, the retardation of the liquid crystal layer is compensated by the retardation layer formed inside the cell, the white display coloring problem is solved, and the viewing angle is compensated. Such optical compensation can be performed.

  Embodiments of a liquid crystal display device and a method for manufacturing the same according to the present invention will be described below with reference to the drawings.

(First embodiment)
In the first embodiment, a liquid crystal display device capable of compensating the optical rotation of a liquid crystal layer by a retardation layer formed inside a cell in a normally black mode transflective liquid crystal display device and a method for manufacturing the same will be described.
FIG. 1 is a diagram showing a schematic configuration of a normally black mode transflective liquid crystal display device according to the present embodiment.

  The liquid crystal display device shown in FIG. 1 is configured such that a liquid crystal layer 30 is sandwiched between a pair of first and second substrates 10 and 20 that are arranged to face each other and are made of glass or the like. The pair of first and second substrates 10 and 20 and the liquid crystal layer 30 constitute a liquid crystal cell. Polarizing plates 41 and 42 are provided outside the first substrate 10 and the second substrate 20.

  An interlayer film 11 is formed on the liquid crystal layer 30 side of the first substrate 10, and a reflective electrode 12 made of silver or the like is formed on the interlayer film 11 to define a reflective portion. A transparent electrode 13 made of ITO (Indium Tin Oxide) or the like is formed in the region from which the interlayer film 11 has been removed, thereby defining a transmission portion. An alignment film 14 made of polyimide or the like that regulates the alignment direction of the liquid crystal layer 30 is formed on the reflective electrode 12 and the transparent electrode 13, and the surface of the alignment film 14 is rubbed. A reflective electrode 12 and a transparent electrode 13 are formed for each pixel.

  A color filter 21 is formed on the liquid crystal layer 30 side of the second substrate 20. The color filter 21 is a resin layer colored in each color with a dye or a pigment. In the present embodiment, the color filter 21 includes a red color filter 21R, a green color filter 21G, and a blue color filter 21B. Any one of the color filters 21R, 21G, and 21B is formed in one pixel having the reflective electrode 12 and the transparent electrode 13.

  On the liquid crystal layer 30 side of the color filter 21, a retardation layer 22, a counter electrode 23 made of a transparent electrode such as ITO, and an alignment film 24 that regulates the alignment direction of the liquid crystal layer 30 through an alignment film (not shown). Is formed.

  The retardation layer 22 is made of, for example, a UV curable liquid crystal polymer having a refractive index anisotropy Δn = 0.12 and is provided inside the cell. As will be described later, the retardation layer 22 has a twist arrangement in which liquid crystal molecules are twisted by adding a chiral agent. The thickness of the retardation layer 22 is adjusted so as to function as a λ / 2 plate. When the twist angle is 30 °, the thickness is, for example, 2.2 μm.

  The liquid crystal layer 30 is made of, for example, nematic liquid crystal having a refractive index anisotropy Δn = 0.08, and is horizontally aligned by the alignment films 14 and 24. When the voltage applied between the reflective electrode 12 or the transparent electrode 13 and the counter electrode 23 is in a low voltage state (including no voltage application state, hereinafter referred to as an OFF state), the liquid crystal molecules in the liquid crystal layer 30 are horizontally aligned. In a high voltage state (hereinafter referred to as an ON state), the liquid crystal molecules in the liquid crystal layer 30 move in the vertical direction. As will be described later, the liquid crystal layer 30 has a twist arrangement in which liquid crystal molecules are twisted. The film thickness of the liquid crystal layer 30 is adjusted to be λ / 4 at the reflection portion and λ / 2 at the transmission portion. When the twist angle of the liquid crystal layer 30 is 30 °, the distance (cell gap) between the first substrate 10 and the second substrate 20 in the transmission portion is, for example, 3.9 μm.

  FIG. 2 is a diagram for explaining a configuration of a normally black mode transflective liquid crystal display device according to the present embodiment.

  If the transmission axis of the polarizing plate 41 on the front side is 90 °, the axis of the retardation layer 22 is 75 ° on average, the axis of the liquid crystal layer 30 is 15 ° on average, and the transmission axis of the polarizing plate 42 on the back side is 60 °. When the voltage is turned off, a black display is obtained at the reflecting portion and the transmissive portion, and when the voltage is turned on, white display is obtained at the reflecting portion and the transmissive portion.

  In the present embodiment, the liquid crystal molecules of the liquid crystal layer 30 are twisted. Accordingly, in order to set the axis of the liquid crystal layer 30 (the alignment direction of the liquid crystal molecules) to 15 ° on average, the liquid crystal molecules in the liquid crystal layer 30 are twisted between 0 ° and 30 °, for example.

  Similarly, in the present embodiment, the liquid crystal molecules of the retardation layer 22 made of a liquid crystal polymer are twisted. Therefore, in order to set the axis of the retardation layer 22 (the alignment direction of the liquid crystal molecules) to 75 ° on average, the liquid crystal molecules in the retardation layer 22 are twisted between 60 ° and 90 °, for example.

  FIG. 3 is a diagram for explaining the twisting of the liquid crystal molecules of the liquid crystal layer 30 and the retardation layer 22.

  As shown in FIG. 3, in the liquid crystal layer 30, the liquid crystal molecules 30 a are twisted from the first substrate 10 toward the second substrate 20 around the line VL perpendicular to the first and second substrates 10 and 20. It has a twisted array. In this example, the liquid crystal molecules 30a have a twisted arrangement in which the liquid crystal molecules 30a are twisted by left rotation from the first substrate 10 to the second substrate 20.

  Similarly, the retardation layer 22 has a twisted arrangement in which the liquid crystal molecules 22 a are twisted from the first substrate 10 toward the second substrate 20 around the vertical line VL. The liquid crystal molecules 22a of the phase difference layer 22 are twisted in the opposite rotational direction to the rotational direction of the twist of the liquid crystal molecules 30a of the liquid crystal layer 30, that is, clockwise.

  As described above, in order to compensate for the optical rotation when the liquid crystal layer is twisted to increase the gap margin of the normally black mode transflective liquid crystal display device, The liquid crystal molecules are twisted. Thus, in order to compensate for the optical rotation of the liquid crystal layer 30, it is particularly preferable to twist in the direction opposite to the twist of the liquid crystal layer 30.

  Further, it is preferable that the twist angle of the liquid crystal molecules 22 a of the retardation layer 22 is substantially the same as the twist angle of the liquid crystal molecules 30 a of the liquid crystal layer 30. “Substantially the same” means that the difference between the twist angle of the liquid crystal molecules 22 a of the retardation layer 22 and the twist angle of the liquid crystal molecules 30 a of the liquid crystal layer 30 is within a range of ± 5 °. The twist angle is the twist angle of the upper and lower liquid crystal molecules. The twist angle of the liquid crystal layer 30 is greater than 0 ° and not greater than 90 °, for example, 30 ° as described above. Accordingly, the twist angle of the phase difference layer 22 is also set to be larger than 0 ° and not larger than 90 °, for example, 30 ° as described above.

  FIG. 4 is a cross-sectional view showing an example of a detailed configuration of the first substrate 10 of the liquid crystal display device according to the present embodiment.

  As shown in FIG. 4, for example, a bottom gate type thin film transistor Tr is formed on a first substrate 10 made of glass or the like. That is, a gate insulating film 16 made of silicon oxide or the like is formed on the entire surface of the first substrate 10 so as to cover the gate electrode 15. A semiconductor thin film 17 made of polysilicon or the like is formed on the gate electrode 15 via a gate insulating film 16.

  A first interlayer film 11a made of silicon oxide or the like is formed so as to cover the thin film transistor Tr, and a source electrode (signal electrode) 18a and a drain electrode 18b embedded in the first interlayer film 11a are formed of the thin film transistor Tr. Is electrically connected. The source electrode 18a and the drain electrode 18b are formed by patterning aluminum, for example.

  A transparent electrode 13 made of ITO or the like connected to the drain electrode 18b is patterned on the first interlayer film 11a. A second interlayer film 11b made of silicon oxide or the like is formed on the entire surface so as to cover the source electrode 18a, the drain electrode 18b, and the transparent electrode 13, and through a contact hole formed in the second interlayer film 11b. The reflective electrode 12 is connected to the drain electrode 18b.

  The part of the second interlayer film 11 b that becomes the transmission part is removed, and the transparent electrode 13 is opened. Note that the alignment film 14 shown in FIG. 1 is formed on the reflective electrode 12 and the transparent electrode 13.

  In the liquid crystal display device according to the above-described embodiment, in the normally black mode transflective liquid crystal display device, the retardation layer 22 made of a liquid crystal polymer is provided inside the liquid crystal cell in order to increase the gap margin. In order to compensate for the optical rotation of the liquid crystal layer 30 having a twist arrangement in which the liquid crystal molecules are twisted, the liquid crystal molecules in the retardation layer 22 are twisted. Therefore, a liquid crystal display device having a large gap margin, high contrast, a wide viewing angle, and good display characteristics can be realized.

  The manufacturing method of the liquid crystal display device according to the present embodiment will be described with reference to the flowchart of FIG. 5 focusing on the manufacturing method on the second substrate 20 side.

  First, after forming the three color filters 21 on the second substrate 20 made of glass or the like (step ST1), polyimide is applied on the color filter 21 to form an alignment film (step ST2). The surface is rubbed (step ST3). This alignment film is for aligning liquid crystal molecules of the retardation layer 22 to be formed later.

  Next, a UV curable liquid crystal to which a chiral agent is added is spin-coated (step ST4), and in a state where annealing for aligning the liquid crystal is performed, the liquid crystal polymer is cured by exposure with UV light and is made of a liquid crystal polymer. Layer 22 is formed (step ST5). The twist angle and twist rotation direction of the liquid crystal molecules of the liquid crystal polymer constituting the retardation layer 22 are controlled by a chiral agent.

  Next, ITO is sputtered to form the counter electrode 23 (step ST6), and the alignment film 24 made of polyimide is formed, whereby the second substrate 20 as the counter substrate is manufactured.

  Thereafter, the second substrate 20 is bonded to the first substrate 10 having a reflective portion and a transmissive portion in a separately manufactured pixel, and then a liquid crystal cell is manufactured by injecting liquid crystal. A liquid crystal display device is manufactured by bonding the polarizing plates 41 and 42 to each other (step ST7). The twist angle of the liquid crystal layer 30 is controlled by the upper and lower alignment films 14 and 24, and the rotational direction of twist is controlled by a chiral agent.

  As described above, the normally black mode transflective liquid crystal display device according to this embodiment is manufactured.

  According to the manufacturing method of the liquid crystal display device according to the present embodiment, in the formation of the retardation layer 22 inside the liquid crystal cell, the optical rotation of the liquid crystal layer 30 is performed by curing the UV curable liquid crystal added with the chiral agent by exposure. The retardation layer 22 with compensated properties can be produced.

  Therefore, a normally black mode transflective liquid crystal display device with a wide gap margin and good display characteristics can be manufactured at low cost.

(Second Embodiment)
In the second embodiment, in a normally black mode transflective liquid crystal display device, a liquid crystal display device capable of preventing a coloring phenomenon in white display by a retardation layer formed inside the cell, and a manufacturing method thereof will be described. .

  FIG. 6 is a diagram showing a schematic configuration of a normally black mode transflective liquid crystal display device according to the present embodiment.

  As shown in FIG. 6, in the present embodiment, the red color filter 21R, the green color filter 21G, and the blue color filter 21B formed on the second substrate 20 are formed to have different film thicknesses. A step is formed on the phase difference layer 22 side.

  A retardation layer 22 is formed on the color filters 21R, 21G, and 21B. The retardation layer 22 is formed on a red retardation layer 22R formed on a red pixel and a green pixel. The green retardation layer 22G and the blue retardation layer 22B formed on the blue pixel.

  The retardation value of the retardation layer 22 depends on the film thickness, the wavelength of incident light, and the refractive index anisotropy Δn. That is, the retardation layer has wavelength dispersion, and it is necessary to compensate for each color in accordance with it. In the material used in the present embodiment, for example, the red retardation layer 22R has a thickness of 3.0 μm because Δn = 0.11 and the green retardation layer 22G has a thickness of Δn = 0.12. The thickness was 2.3 μm, and the thickness of the blue retardation layer 22B was 1.7 μm because Δn = 0.13. Thereby, a phase difference value of λ / 2 is obtained in accordance with the wavelength region of the light transmitted through the color filters 21R, 21G, and 21B.

  Similarly, the liquid crystal layer 30 is also provided with a step so that the retardation is adjusted according to the wavelength of each pixel. Other points are the same as in the first embodiment. In the present embodiment, the liquid crystal molecules of the liquid crystal layer 30 and the liquid crystal molecules of the retardation layer 22 may or may not be twisted.

  In the liquid crystal display device described above, the film thicknesses of the color filters 21R, 21G, and 21B are changed in the process of forming the color filter 21 (step ST1 in FIG. 5) in the manufacturing process of the liquid crystal display device according to the first embodiment. It is manufactured by forming. Other processes are the same as those in the first embodiment.

  In the present embodiment, in the normally black mode transflective liquid crystal display device, the retardation layer 22 made of a liquid crystal polymer is provided inside the liquid crystal cell, and the color filter 21R is used to eliminate the coloring problem in white display. , 21G, 21B, the thickness of each of the retardation layers 22R, 22G, 22B is made different so as to obtain a retardation value of λ / 2 in accordance with the wavelength region of the light transmitted through each of the retardation layers 22G, 21B.

  That is, when the incident wavelength of light to the red pixel is 600 nm, the incident wavelength of light to the green pixel is 550 nm, and the incident wavelength of light to the blue pixel is 450 nm, the phase difference layers 22R and 22G are set to λ / 4 of each wavelength. , 22B are matched to each other, and when white display is performed by applying a voltage, the transmittance of red light, green light and blue light can be made uniform, and a good white display can be obtained. Further, with respect to the liquid crystal layer 30 as well, a good black display can be obtained by providing a step and adjusting the retardation in accordance with the wavelength of each pixel.

  FIG. 7A shows the light of the normally black mode transflective liquid crystal display device according to the present embodiment during white display (indicated by W in the figure) and black display (indicated by B in the figure). It is a figure which shows the relationship between a wavelength and the transmittance | permeability. As shown in FIG. 7A, in this embodiment, the transmittance can be made substantially uniform over all wavelength regions of red light, green light, and blue light, and good white display and black display can be obtained. It has been confirmed that

  FIG. 7B shows a comparative example in which a liquid crystal display device is manufactured by making the thickness of the retardation layer 22 uniform at 2.2 μm without providing a step in the color filter 21. It is a figure which shows the relationship between the wavelength of light, and the transmittance | permeability at the time of white display (it shows with B in a figure) and black display (it shows with B in a figure) of the transflective liquid crystal display device of a Marie black mode. As shown in FIG. 7B, in the comparative example, the retardation value of the retardation layer is matched to the green of the center wavelength, so that the transmittance of blue light and red light is small, and the green is slightly green when displaying white. It has become a different color. Further, in the comparative example, since the retardation value of the liquid crystal layer is not adjusted for each pixel, complete black cannot be obtained and the liquid crystal layer is colored.

  As described above, according to the above-described liquid crystal display device according to the present embodiment, in the normally black mode transflective liquid crystal display device, the liquid crystal cell includes the liquid crystal polymer, and the color filters 21R, 21G, Since the retardation layers 22R, 22B, and 22G whose retardation values are adjusted in accordance with the wavelength region of the light transmitted by 21B are formed, it is possible to realize a liquid crystal display device capable of obtaining good white display. Further, with respect to the liquid crystal layer 30 as well, a good black display can be obtained by providing a step and adjusting the retardation in accordance with the wavelength of each pixel.

  In addition, according to the method of manufacturing the liquid crystal display device according to the present embodiment, the color filters 21R, 21G, and 21B are formed with different film thicknesses, and the step formed on the surface thereof is used to obtain the retardation layer. The phase difference value can be adjusted by changing the film thickness of 22R, 22B, and 22G. Further, with respect to the liquid crystal layer 30 as well, a satisfactory black display can be obtained by changing the film thickness in accordance with the wavelength of each pixel by using the step and adjusting the retardation value. Accordingly, a normally black mode transflective liquid crystal display device capable of obtaining good white display and black display can be manufactured at low cost.

(Third embodiment)
In the third embodiment, in a normally black mode transflective liquid crystal display device, a coloring phenomenon in white display can be prevented by a retardation layer formed inside the cell by a method different from the second embodiment. A liquid crystal display device and a manufacturing method thereof will be described.

  FIG. 8 is a diagram showing a main configuration of the second substrate 20 side in the normally black mode transflective liquid crystal display device according to the present embodiment. The counter electrode 23 and the alignment film 24 omitted in FIG. 8 and the configuration on the first substrate 10 side are the same as in the second embodiment.

  In the present embodiment, the retardation layer 22 includes a red retardation layer 22R formed on a red pixel, a green retardation layer 22G formed on a green pixel, and a blue retardation layer formed on a blue pixel. And the retardation layer 22B. The phase difference layers 22R, 22G, and 22B have the same film thickness, but a phase difference value of λ / 2 is obtained in accordance with the wavelength region of light transmitted through the color filters 21R, 21G, and 21B. The phase difference layers 22R, 22G, and 22B have different refractive index anisotropy Δn.

  About another point, it is the same as that of 2nd Embodiment. In the present embodiment, the liquid crystal molecules of the liquid crystal layer 30 and the liquid crystal molecules of the retardation layer 22 may or may not be twisted.

  In the liquid crystal display device according to the first embodiment, in the exposure process of UV curable liquid crystal using ultraviolet light (step ST5 in FIG. 5) in the manufacturing process of the liquid crystal display device according to the first embodiment, as shown below, UV curing of each pixel is performed. The retardation layers 22R, 22G, and 22B in which the retardation values are adjusted by varying the refractive index anisotropy can be produced by curing the liquid crystalline liquid crystal.

  For example, after the UV curable liquid crystal is spin-coated, only the UV curable liquid crystal of the red pixel is irradiated with ultraviolet light and cured using a mask in a state where the UV curable liquid crystal is controlled to the first temperature.

  Similarly, in a state where the UV curable liquid crystal is controlled to the second temperature, only the UV curable liquid crystal of the green pixel is irradiated with ultraviolet light and cured using a mask, and the UV curable liquid crystal is In a state where the temperature is controlled, only the UV curable liquid crystal of the blue pixel is irradiated with ultraviolet light and cured using a mask.

  In order to obtain a phase difference value of λ / 2 in each of the phase difference layers 22R, 22G, and 22B in accordance with the wavelength region of the light transmitted through the color filters 21R, 21G, and 21B, the first temperature described above is used. Is made the smallest and the third temperature is made the largest. Thereby, the retardation layers 22R, 22G, and 22B in which the retardation value is adjusted for each pixel are manufactured.

  As described above, according to the above-described liquid crystal display device according to the present embodiment, a liquid crystal display device capable of obtaining a good white display can be realized as in the second embodiment.

  In addition, according to the method for manufacturing a liquid crystal display device according to the present embodiment, in the step of curing the UV curable liquid crystal by irradiation with ultraviolet light, the temperature of the UV curable liquid crystal is made different for each pixel, whereby the retardation layer is obtained. The phase difference values of 22R, 22B, and 22G can be adjusted. Accordingly, a normally black mode transflective liquid crystal display device capable of obtaining good white display can be manufactured at low cost.

(Fourth embodiment)
In the fourth embodiment, in a normally black mode transflective liquid crystal display device, a coloring phenomenon in white display can be prevented by a retardation layer formed inside the cell by a method different from that in the second embodiment. A liquid crystal display device and a manufacturing method thereof will be described.

  FIG. 9 is a diagram showing a main configuration of the second substrate 20 side in the normally black mode transflective liquid crystal display device according to the present embodiment. The configuration of the counter electrode 23 and the alignment film 24 omitted in FIG. 9 and the first substrate 10 side are the same as in the second embodiment.

  In the present embodiment, the retardation layer 22 includes a red retardation layer 22R formed on a red pixel, a green retardation layer 22G formed on a green pixel, and a blue retardation layer formed on a blue pixel. And the retardation layer 22B. In the present embodiment, the thickness of each of the retardation layers 22R, 22G, and 22B is different so that a retardation value of λ / 2 can be obtained in accordance with the wavelength region of light transmitted through the color filters 21R, 21G, and 21B. It is

  About another point, it is the same as that of 2nd Embodiment. In the present embodiment, the liquid crystal molecules of the liquid crystal layer 30 and the liquid crystal molecules of the retardation layer 22 may or may not be twisted.

  In the above liquid crystal display device manufacturing process of the liquid crystal display device according to the first embodiment, the UV curable liquid crystal is exposed to ultraviolet light (step ST5 in FIG. 5). By controlling the exposure amount to the curable liquid crystal, the retardation layers 22R, 22G, and 22B having different film thicknesses can be produced.

  For example, after spin-coating the UV curable liquid crystal, the UV curable liquid crystal is irradiated with ultraviolet light at the first exposure amount only on the UV curable liquid crystal of the red pixel using a mask while the UV curable liquid crystal is controlled at a predetermined temperature. To cure.

  Similarly, in a state where the UV curable liquid crystal is controlled at a predetermined temperature, only the UV curable liquid crystal of the green pixel is irradiated with ultraviolet light at the second exposure amount using a mask, and further UV curable. In a state where the liquid crystal is controlled at a predetermined temperature, only the UV curable liquid crystal of the blue pixel is irradiated with ultraviolet light with a third exposure amount and cured using a mask.

  Then, after the exposure, the UV curable liquid crystal in the uncured portion is removed with a developer. Thereby, since an uncured part decreases as the exposure amount increases, the thickness of the retardation layer increases as the exposure amount increases. Therefore, the first exposure amount is maximized and the third exposure amount is minimized. Thereby, the phase difference layers 22R, 22G, and 22B in which the phase difference values are adjusted can be manufactured.

  As described above, according to the above-described liquid crystal display device according to the present embodiment, a liquid crystal display device capable of obtaining a good white display can be realized as in the second embodiment.

  Further, according to the method for manufacturing a liquid crystal display device according to the present embodiment, in the step of exposing the UV curable liquid crystal with ultraviolet light, the exposure amount to the UV curable liquid crystal is changed for each pixel, so that The film thickness of the retardation layers 22R, 22B, and 22G can be adjusted, and as a result, the retardation value of each of the retardation layers 22R, 22B, and 22G can be adjusted. Accordingly, a normally black mode transflective liquid crystal display device capable of obtaining good white display can be manufactured at low cost.

(Fifth embodiment)
In the present embodiment, a liquid crystal display device capable of compensating a viewing angle by a retardation layer formed in a cell in a normally black mode transflective liquid crystal display device and a method for manufacturing the same will be described.

  The basic configuration of the normally black mode transflective liquid crystal display device according to this embodiment is the same as that of the first embodiment shown in FIG.

  In the present embodiment, the liquid crystal molecules in the liquid crystal layer 30 are tilted in a predetermined direction on the substrate surface at a predetermined pretilt angle. In order to eliminate the influence on the viewing angle due to this tilt, the liquid crystal molecules are formed within the cell. The liquid crystal molecules in the phase difference layer 22 are aligned in a direction opposite to the predetermined direction with respect to the substrate surface.

  Other points are the same as in the first embodiment. In the present embodiment, the liquid crystal molecules of the liquid crystal layer 30 and the liquid crystal molecules of the retardation layer 22 may or may not be twisted.

  FIG. 10 is a diagram for explaining the inclination of the liquid crystal molecules of the liquid crystal layer 30 and the retardation layer 22.

  As shown in FIG. 10, the liquid crystal molecules 30 a in the liquid crystal layer 30 are aligned at a predetermined pretilt angle α so as to tilt upward to the right with respect to the substrate surface. The reason for tilting is that when a voltage is applied to the liquid crystal layer 30, the major axis of the liquid crystal molecules 30a is aligned in the direction of the electric field (perpendicular to the substrate). This is because the display characteristics are improved by controlling.

  Thus, in the case where the liquid crystal molecules 30a of the liquid crystal layer 30 are arranged to tilt to the right with the pretilt angle α, the retardation layer 22 formed inside the cell is eliminated in order to eliminate the influence on the viewing angle due to this tilt. The liquid crystal molecules 22a of the liquid crystal layer 30 are aligned in the direction opposite to the liquid crystal molecules 30a of the liquid crystal layer 30, that is, in the upward direction, by a pretilt angle β. In order to eliminate the influence on the viewing angle, it is preferable that the pretilt angle α and the pretilt angle β are substantially the same. For example, both are controlled to about 4 °.

  The pretilt angle of the liquid crystal molecules 22a of the retardation layer 22 of the liquid crystal display device is determined by the rubbing direction in the rubbing process (step ST3 in FIG. 5) and the UV curing property in the manufacturing process of the liquid crystal display device of the first embodiment. By controlling the temperature during exposure of the liquid crystal (step ST5 in FIG. 5), a desired value can be obtained. Also, the pretilt angle can be controlled by the optical orientation. Other processes are the same as those in the first embodiment.

  As described above, in the liquid crystal display device according to the above-described embodiment, in the normally black mode transflective liquid crystal display device, the retardation layer 22 made of a liquid crystal polymer is provided inside the liquid crystal cell, and the retardation is increased. The liquid crystal molecules 22a of the layer 22 are aligned in a direction opposite to the liquid crystal molecules 30a of the liquid crystal layer 30 in the opposite direction. Therefore, the influence on the viewing angle due to the tilt of the liquid crystal molecules 30a of the liquid crystal layer 30 can be compensated, and a liquid crystal display device having a wide viewing angle can be realized.

  Further, according to the method of manufacturing the liquid crystal display device according to the present embodiment, the pretilt angle of the liquid crystal molecules 22a of the retardation layer 22 can be easily controlled by adjusting the rubbing direction of the alignment film and the temperature during exposure. Can do. Accordingly, a normally black mode transflective liquid crystal display device with a wide viewing angle can be manufactured at low cost. In addition, the same effect can be obtained by controlling the pretilt angle depending on the photo-alignment.

The present invention is not limited to the description of the above embodiment.
For example, it can be combined with the first to fifth embodiments as appropriate. In the fourth embodiment (see FIG. 9), as a method of changing the film thickness of the retardation layers 22R, 22G, and 22B for each pixel, in addition to adjusting the exposure amount, UV curable liquid crystal is used by inkjet or the like. The red, green, and blue pixels are applied with different film thicknesses and then cured by irradiation with ultraviolet light, so that the retardation layers 22R, 22G, and 22B can be formed in accordance with the wavelength region of the light to be used.
In addition, various modifications can be made without departing from the scope of the present invention.

1 is a diagram illustrating a schematic configuration of a normally black mode transflective liquid crystal display device according to a first embodiment. FIG. It is a figure for demonstrating the structure of the transflective liquid crystal display device of the normally black mode which concerns on this embodiment. It is a figure for demonstrating twist of the liquid crystal molecule of a liquid crystal layer and a phase difference layer. It is sectional drawing which shows an example of the detailed structure of the 1st board | substrate of the liquid crystal display device which concerns on this embodiment. 4 is a flowchart for explaining a method of manufacturing the liquid crystal display device according to the first embodiment. It is a figure which shows schematic structure of the transflective liquid crystal display device of the normally black mode which concerns on 2nd Embodiment. It is a figure which shows the measurement result of the wavelength and the transmittance | permeability of the light at the time of white display of the transflective liquid crystal display device of normally black mode, (a) shows the measurement result of 2nd Embodiment, (b) is a comparison. The measurement result of an example is shown. It is a figure which shows the principal part structure by the side of the 2nd board | substrate in the transflective liquid crystal display device of the normally black mode which concerns on 3rd Embodiment. FIG. 10 is a diagram illustrating a main configuration of a second substrate side in a normally black mode transflective liquid crystal display device according to a fourth embodiment. FIG. 10 is a diagram for explaining inclinations of liquid crystal molecules in a liquid crystal layer and a retardation layer in a normally black mode transflective liquid crystal display device according to a fifth embodiment. It is a figure which shows schematic structure of the transflective liquid crystal display device of the conventional normally white mode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... 1st board | substrate, 11 ... Interlayer film, 11a ... 1st interlayer film, 11b ... 2nd interlayer film, 12 ... Reflective electrode, 13 ... Transparent electrode, 14 ... Alignment film, 15 ... Gate electrode, 16 ... Gate insulating film, 17 ... Semiconductor thin film, 18a ... Source electrode, 18b ... Drain electrode, 20 ... Second substrate, 21 ... Color filter, 21R ... Red color filter, 21G ... Green color filter, 21B ... Blue color filter, 22 ... retardation layer, 22R ... red retardation layer, 22G ... green retardation layer, 22B ... blue retardation layer, 23 ... counter electrode, 24 ... alignment film, 30 ... liquid crystal layer, 41 ... polarizing plate, 42 ... Polarizing plate, 110 ... first substrate, 111 ... interlayer film, 112 ... reflection electrode, 113 ... transparent electrode, 114 ... λ / 4 plate, 115 ... λ / 2 plate, 116 ... polarizing plate, 120 ... second Substrate, 121 ... counter electrode, 1 22 ... λ / 4 plate, 123 ... λ / 2 plate, 124 ... Polarizing plate

Claims (15)

A liquid crystal display device provided with a reflective portion and a transmissive portion, wherein the voltage applied to the liquid crystal layer displays black in a low voltage state and displays white in a high voltage state,
A pair of substrates provided with the reflecting portion and the transmitting portion;
The liquid crystal layer sandwiched between the pair of substrates and having a twist arrangement in which liquid crystal molecules are twisted;
A liquid crystal display device comprising: a retardation layer formed between one of the pair of substrates and the liquid crystal layer, made of a liquid crystal polymer, and having a twist arrangement in which liquid crystal molecules in the liquid crystal polymer are twisted . The liquid crystal display device according to claim 1, wherein the retardation layer has a twist arrangement twisted in a rotation direction opposite to a rotation direction of twist of liquid crystal molecules in the liquid crystal layer. The liquid crystal display device according to claim 1, wherein the retardation layer has a twist angle substantially the same as a twist angle of the liquid crystal molecules of the liquid crystal layer in the transmission portion. A liquid crystal display device having a pixel provided with a reflective portion and a transmissive portion and displaying black in a low voltage state and white in a high voltage state when a voltage applied to a liquid crystal layer sandwiched between a pair of substrates is ,
A plurality of kinds of color filters formed between any one of the pair of substrates and the liquid crystal layer, and having different wavelength regions of light to be transmitted for each pixel;
A phase difference value is adjusted for each pixel in accordance with a wavelength region of light that is formed between any one of the pair of substrates and the liquid crystal layer, is made of a liquid crystal polymer, and is transmitted through the color filter. A liquid crystal display device comprising: a retardation layer. The liquid crystal display device according to claim 4, wherein the retardation value is adjusted by adjusting a film thickness of the retardation layer for each pixel. The liquid crystal display device according to claim 4, wherein a phase difference value of the liquid crystal layer is adjusted by adjusting a gap between the liquid crystal layers sandwiched between the pair of substrates for each pixel. The color filter and the retardation layer are formed on the same substrate,
The liquid crystal display device according to claim 4, wherein a step is provided on a surface of the color filter, and the retardation value is adjusted by adjusting a film thickness of the retardation layer for each pixel by the step. A liquid crystal display device provided with a reflective portion and a transmissive portion, wherein the voltage applied to the liquid crystal layer displays black in a low voltage state and displays white in a high voltage state,
A pair of substrates provided with the reflecting portion and the transmitting portion;
The liquid crystal layer sandwiched between the pair of substrates and having liquid crystal molecules arranged in a predetermined direction with respect to the substrate surface;
The liquid crystal polymer is formed between any one of the pair of substrates and the liquid crystal layer, and the liquid crystal molecules in the liquid crystal polymer are in a direction opposite to the predetermined direction with respect to the substrate surface. A liquid crystal display device comprising: a retardation layer arranged to be inclined. A liquid crystal display device having a pair of substrates provided with a reflective portion and a transmissive portion, wherein the voltage applied to the liquid crystal layer sandwiched between the pair of substrates displays black in a low voltage state and displays white in a high voltage state A manufacturing method of
Forming a UV curable liquid crystal added with a chiral agent on one of the pair of substrates;
Curing the UV curable liquid crystal by irradiating it with ultraviolet light, and forming a retardation layer comprising a liquid crystal polymer having a twist arrangement in which liquid crystal molecules are twisted;
Forming the liquid crystal layer having a twisted arrangement in which liquid crystal molecules are twisted between the pair of substrates so that the one substrate and the other substrate are opposed to each other. A method of manufacturing a liquid crystal display device having a pixel provided with a reflective portion and a transmissive portion, wherein the voltage applied to a liquid crystal layer sandwiched between a pair of substrates displays black in a low voltage state and white in a high voltage state Because
Forming a plurality of types of color filters having different wavelength regions of light for each pixel on one of the pair of substrates;
A step of forming a retardation layer made of a liquid crystal polymer and adjusting a retardation value for each pixel in accordance with a wavelength region of light transmitted through the color filter on the one substrate or the other substrate;
And a step of forming the liquid crystal layer between the pair of substrates so that the one substrate and the other substrate are opposed to each other. In the step of forming the color filter, forming the color filter having a step on the surface by varying the film thickness for each pixel,
The step of forming the retardation layer includes adjusting the retardation value by forming the retardation layer on the color filter and varying the thickness of the retardation layer for each pixel by the step. 10. A method for producing a liquid crystal display device according to 10. The step of forming the retardation layer includes
Forming a UV curable liquid crystal on the one substrate or the other substrate;
The method of manufacturing a liquid crystal display device according to claim 10, further comprising: curing the UV curable liquid crystal by irradiating each pixel with ultraviolet light in a state where the temperature of the UV curable liquid crystal is controlled. The method of manufacturing a liquid crystal display device according to claim 12, wherein in the step of curing the UV curable liquid crystal, the retardation value is adjusted by changing the temperature of the UV curable liquid crystal for each pixel. The liquid crystal display device manufacturing method according to claim 12, wherein, in the step of curing the UV curable liquid crystal, the retardation value is adjusted by varying an exposure amount of ultraviolet light applied to the UV curable liquid crystal for each pixel. Method. A method of manufacturing a liquid crystal display device provided with a reflective portion and a transmissive portion, wherein the voltage applied to the liquid crystal layer displays black in a low voltage state and displays white in a high voltage state,
Forming a retardation layer made of a liquid crystal polymer in which liquid crystal molecules are arranged in a predetermined direction with respect to a substrate surface on one of the pair of substrates;
Forming the liquid crystal layer in which liquid crystal molecules are arranged in a direction opposite to the predetermined direction with respect to the substrate surface, with the one substrate facing the other substrate.

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