JP3974368B2 - Liquid crystal display device and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display device having a high-speed response and a wide viewing angle, and more particularly to an optical compensation bend mode (OCB mode) liquid crystal display device and a method of manufacturing the liquid crystal display device. .
[0002]
[Prior art]
In recent years, a large amount of image information has been distributed with the progress of multimedia technology. As means for displaying such image information, liquid crystal display devices are rapidly spreading. This is because liquid crystal display devices with high contrast and wide viewing angles have been developed and put into practical use due to the development of liquid crystal technology. At present, the display performance of liquid crystal display devices has reached a level comparable to that of CRT displays.
[0003]
However, since the response speed of the liquid crystal is not sufficient, there is a problem that the liquid crystal display device is not suitable for moving image display. That is, in the current NTSC (National Television System Committee) system, although the liquid crystal needs to respond within one frame period (16.7 msec), the current liquid crystal display device performs multi-gradation display. In some cases, the response between gradations requires 100 msec or more. Therefore, a phenomenon that an image flows in moving image display occurs. In particular, since the response between gradations in a region where the driving voltage is low is remarkably slow, it is impossible to realize a good moving image display.
[0004]
Therefore, many attempts have been made to increase the response speed of liquid crystal display devices. Various liquid crystal display systems with high-speed response have been compiled by Wu et al. (CS Wu and ST Wu, SPIE, 1665, 250 (1992)), but a system that can expect response characteristics necessary for moving image display is The current situation is limited.
[0005]
At present, a liquid crystal display device having a high-speed response suitable for moving image display is promising as being equipped with an OCB mode liquid crystal display element, a ferroelectric liquid crystal display element, or an antiferroelectric liquid crystal display element.
[0006]
Among these, ferroelectric liquid crystal display elements and antiferroelectric liquid crystal display elements having a layer structure are practical in meaning such as low impact resistance, narrow operating temperature range, and large temperature dependence of characteristics. There are many challenges. Therefore, in reality, an OCB mode liquid crystal display element using a nematic liquid crystal has attracted attention as a liquid crystal display element suitable for moving image display.
[0007]
This OCB mode liquid crystal display element was demonstrated in 1983 by J.P.Bos for its high speed. After that, it was shown that a display that can achieve both a wide viewing angle and high-speed response by providing a phase difference plate, and research and development became active.
[0008]
FIG. 24 is a cross-sectional view schematically showing a configuration of a conventional OCB mode liquid crystal display element. As shown in FIG. 24, this OCB mode liquid crystal display element includes a glass substrate 1 on which the transparent electrode 2 is formed on the lower surface, and a glass substrate 8 on which the transparent electrode 7 is formed on the upper surface. A liquid crystal layer 4 is disposed between the glass substrates 1 and 8. An alignment film 3 is formed on the lower surface of the transparent electrode 2, and an alignment film 6 is formed on the upper surface of the transparent electrode 7, and liquid crystal molecules 4 are filled in the gaps between the alignment films 3 and 6 to form the liquid crystal layer 4. Is formed. In addition, the alignment films 3 and 6 are subjected to an alignment process to align liquid crystal molecules in parallel and in the same direction. The layer thickness of the liquid crystal layer 4 is held by the spacer 5.
[0009]
Further, a polarizing plate 13 is provided on the upper surface of the glass substrate 1, and a polarizing plate 16 is provided on the lower surface of the glass substrate 8, and these polarizing plates 13 and 16 are arranged in crossed Nicols. Further, a retardation plate 17 is provided between the polarizing plate 13 and the glass substrate 1, and a retardation plate 18 is provided between the polarizing plate 16 and the glass substrate 8. As the phase difference plates 17 and 18, negative phase difference plates in which the main axes are arranged in a hybrid manner are used.
[0010]
The OCB mode liquid crystal display device configured as described above is characterized in that the alignment state of the liquid crystal is changed from the splay alignment 4a to the bend alignment 4b by applying a voltage, and an image is displayed by this bend alignment state. Such an OCB mode liquid crystal display element has a significantly improved liquid crystal response speed as compared with a TN (Twisted Nematic) mode liquid crystal display element or the like, so that a liquid crystal display device suitable for moving image display can be realized. Further, by providing the phase difference plates 17 and 18, low voltage driving and a wide viewing angle can be realized.
[0011]
[Problems to be solved by the invention]
By the way, the OCB mode liquid crystal display element described above can be configured to include color filters of three primary colors (red, green, and blue) in order to realize color display. Here, the pixels corresponding to the red, green, and blue color filters are referred to as a red pixel, a green pixel, and a blue pixel. FIG. 25 is a graph showing the chromatic dispersion characteristics of the phase difference in the normal direction of the liquid crystal layer related to such red pixels, green pixels, and blue pixels (hereinafter referred to as front phase difference). FIG. 25 shows the front phase difference of the negative retardation plate in which the main axes are hybrid-arranged together with the front phase difference of these liquid crystal layers.
[0012]
In FIG. 25, reference numerals 81, 82, and 83 denote the wavelength dispersion characteristics of the front phase difference of the liquid crystal layer related to the red pixel, the green pixel, and the blue pixel, respectively. Reference numeral 84 denotes the wavelength dispersion characteristic of the front phase difference of the negative retardation plate.
[0013]
As shown in FIG. 25, the front phase difference of the liquid crystal layer in the red pixel and the front phase difference of the negative retardation plate substantially match in the red wavelength region (near 650 nm). Similarly, the front phase difference of the liquid crystal layer in the green pixel and the front phase difference of the negative retardation plate are substantially matched in the green wavelength region (near 550 nm). On the other hand, the front phase difference of the liquid crystal layer in the blue pixel and the front phase difference of the negative retardation plate do not match in the blue wavelength region (near 450 nm). As a result, when the OCB mode liquid crystal display element performs black display, the display is colored blue.
[0014]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide an OCB mode liquid crystal display element capable of performing good black display by reducing blue coloring when performing black display. An object of the present invention is to provide a liquid crystal display device including the liquid crystal display element and a method for manufacturing the liquid crystal display element.
[0015]
[Means for Solving the Problems]
  In order to solve the above-described problems, the liquid crystal display device according to the present invention compensates for the retardation of the liquid crystal layer in which liquid crystal molecules having bend alignment are arranged when performing image display, and the liquid crystal layer. A liquid crystal display element having at least one negative retardation plate for changing the retardation of the liquid crystal layer according to an image signal input from the outside, thereby displaying light for display on the liquid crystal display element In a liquid crystal display device that displays by changing the transmittance,The negative retardation plate is a retardation plate made of an optical medium having negative refractive index anisotropy in which main axes are arranged in a hybrid manner,The liquid crystal display element has a plurality of red pixels for displaying red, green pixels for displaying green, and blue pixels for displaying blue, and the thickness of the liquid crystal layer related to the blue pixels is It is characterized by being larger than the thickness of the liquid crystal layer relating to the red pixel and / or the green pixel.Ru.
[0016]
  By adopting such a configuration, the phase difference in the liquid crystal layer of the blue pixel andNegativeThe phase difference of the retardation plate substantially matches in the blue wavelength region. As a result, it is possible to reduce the blue coloring that occurs when black display is performed. Therefore, good black display can be realized.
[0017]
In this case, the difference between the thickness of the liquid crystal layer related to the blue pixel and the thickness of the liquid crystal layer related to the red pixel and / or the green pixel may be 0.2 μm or more and 1.0 μm or less. 2). The thickness of the liquid crystal layer related to the blue pixel may be 104% or more and 120% or less of the thickness of the liquid crystal layer related to the red pixel and / or the green pixel.
[0018]
Thus, by making the thickness of the liquid crystal layer related to the blue pixel appropriate, the blue coloring in the black display can be sufficiently reduced.
[0019]
Further, in the liquid crystal display device according to the invention, the lighting device having a light source that emits light of each color of red, green, and blue, and the lighting device is controlled so that the light source emits each color light in a time-sharing manner. It is good also as a structure further provided with the illuminating device control means to do (Claim 4). Thereby, it is possible to realize good black display even by a so-called field sequential color system.
[0042]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, in each embodiment, the display color coordinates in the normal direction when the liquid crystal display element performs black display are measured. In this case, the best achromatic display with no color is obtained when the color coordinates are approximately (0.3, 0.3). Therefore, the object of the present invention is to bring the color coordinates close to (0.3, 0.3) in order to realize good black display.
[0043]
(Embodiment 1)
In the first embodiment of the present invention, the thickness of the liquid crystal layer of the blue pixel for displaying blue is made larger than the thickness of the liquid crystal layer of the red pixel and green pixel for displaying red and green, respectively. 1 shows a liquid crystal display device that reduces blue coloring in black display.
[0044]
[Example 1]
FIG. 1 is a cross-sectional view schematically showing a configuration of a liquid crystal display element included in a liquid crystal display device of the present invention according to Example 1 of the present embodiment. In the figure, for convenience, the X direction is the upward direction of the liquid crystal display element.
[0045]
As shown in FIG. 1, the liquid crystal display element 100 included in the liquid crystal display device according to the first embodiment includes a liquid crystal cell 101 described later. On the upper surface of the liquid crystal cell 101, a retardation film 14a (hereinafter, simply referred to as a negative retardation film) made of an optical medium having negative refractive index anisotropy in which the principal axes are arranged in a hybrid manner, a negative uniaxial position. A phase difference film 12a, a positive uniaxial phase difference film 15, and an analyzer 13 are sequentially laminated. A negative retardation film 14b, a negative uniaxial retardation film 12b, and a polarizer 16 are sequentially laminated on the lower surface of the liquid crystal cell 101.
[0046]
2A and 2B are diagrams schematically showing the configuration of the liquid crystal cell 101 described above. FIG. 2A is a cross-sectional view of the liquid crystal cell 101, and FIG. 2B is an enlarged view of a liquid crystal layer portion in the cross-sectional view. As shown in FIG. 2A, the liquid crystal cell 101 includes two substrates, that is, an upper substrate 102 and a lower substrate 103. The upper substrate 102 and the lower substrate 103 are disposed to face each other via a spacer (not shown), and the liquid crystal layer 4 is disposed in a gap formed between the upper substrate 102 and the lower substrate 103. ing. Liquid crystal molecules 201 are injected into the liquid crystal layer 4, and the liquid crystal molecules 201 have bend alignment as shown in FIG. 2B when performing image display.
[0047]
The upper substrate 102 is configured by laminating the transparent electrode 2 and the alignment film 3 in this order on the lower surface of the glass substrate 1. A red color filter 51R, a green color filter 51G, and a blue color filter 51B are formed between the glass substrate 1 and the transparent electrode 2. A light shielding film 52 called a black matrix is provided at each color filter boundary. Hereinafter, pixels corresponding to the red color filter 51R, the green color filter 51G, and the blue color filter 51B are referred to as a red pixel, a green pixel, and a blue pixel, respectively.
[0048]
On the other hand, the lower substrate 103 is configured by sequentially laminating the transparent electrode 7 and the alignment film 6 on the upper surface of the glass substrate 8. The lower substrate 103 has a recess 10 at a position corresponding to the blue pixel. Reference numeral 20 denotes a resist thin film to be described later.
[0049]
FIG. 3 is a plan view of the liquid crystal display element 100 showing the arrangement direction of each optical element included in the liquid crystal display element 100 described above. Referring also to FIG. 1, arrows 17 and 18 indicate alignment processing directions with respect to the upper substrate 102 and the lower substrate 103, respectively. Moreover, the arrows 26 and 27 have shown the principal axis direction of the negative phase difference films 14a and 14b, respectively. As shown in FIG. 3, the negative retardation films 14 a and 14 b are arranged so that their principal axis directions 26 and 27 are the same as the alignment treatment directions 17 and 18.
[0050]
In FIG. 3, an arrow 19 indicates the slow axis of the positive uniaxial retardation film 15. As shown in FIG. 3, the positive uniaxial retardation film 15 is arranged so that the slow axis 19 forms 45 degrees with respect to the alignment treatment directions 17 and 18.
[0051]
Further, in FIG. 3, arrows 24 and 25 indicate the transmission axes of the polarizer 16 and the analyzer 13, respectively. As shown in FIG. 3, the polarizer 16 is arranged so that its transmission axis 24 is in the same direction as the slow axis 19 of the positive uniaxial retardation film 15. On the other hand, the analyzer 13 is arranged so that its transmission axis 25 is orthogonal to the transmission axis 24 of the polarizer 16.
[0052]
In this example, the above-described liquid crystal display element 100 was manufactured as follows. FIG. 4 is a diagram for explaining the process of forming the recess 10 described above. First, a polycarbonate (PC) resist material manufactured by JSR Corporation was applied to the upper surface of the glass substrate 8 to form a resist thin film 20 having a thickness of 0.5 μm. Next, the resist thin film 20 was exposed by irradiating it with a parallel ultraviolet ray 23 with a photomask 21 having a plurality of openings 22 having a rectangular pattern as shown in FIG. The resist thin film 20 exposed in this way was developed and rinsed, and then pre-baked at 90 ° C. to form the recess 10 as shown in FIG.
[0053]
By the way, the opening 22 of the photomask 21 described above is provided corresponding to the position of the blue pixel. Therefore, the concave portion 10 described above is formed corresponding to the blue pixel.
[0054]
After forming the plurality of recesses 10 in this way, a 2000 mm transparent electrode 7 was formed by a known method. Then, an alignment film coating SE-7492 manufactured by Nissan Chemical Industries, Ltd. is applied to the lower surface of the transparent electrode 2 and the upper surface of the transparent electrode 7 by spin coating, respectively, baked at 180 ° C. for 1 hour, and then cured to align the alignment films 3 and 6. Formed.
[0055]
The alignment films 3 and 6 thus formed were each subjected to a rubbing process according to the alignment process directions 17 and 18 shown in FIG. Next, using a spacer manufactured by Sekisui Fine Chemical Co., Ltd. and a struct bond 352A which is a sealing resin manufactured by Mitsui Toatsu Chemical Co., Ltd., the distance between the upper substrate 102 and the lower substrate 103 related to the red and green pixels, That is, the upper substrate 102 and the lower side 102 were bonded so that the thickness of the liquid crystal layer 4 (53R and 53G in FIG. 2) was 5.2 μm. In this case, the thickness (53B in FIG. 2) of the liquid crystal layer 4 of the blue pixel is a value obtained by adding the thickness of the concave portion 10 to the thickness of 5.2 μm, that is, 5.7 μm. Then, a liquid crystal cell 101 was manufactured by injecting liquid crystal MT-5585 (refractive index anisotropy Δn = 0.140) into the liquid crystal layer 4 by a vacuum injection method.
[0056]
In this embodiment, as described above, the thicknesses 53R and 53G of the red and green liquid crystal layers 4 are set to 5.2 μm, and the thickness 53B of the blue pixel liquid crystal layer 4 is set to 5.7 μm. The invention is not limited to this. However, if the difference between the thicknesses 53R and 53G of the liquid crystal layer 4 of the red pixel and the green pixel and the thickness 53B of the liquid crystal layer 4 of the blue pixel is too small, the phase difference in the liquid crystal layer 4 of the blue pixel may be sufficiently increased. become unable. On the other hand, when the difference is too large, the phase difference in the liquid crystal layer 4 of the blue pixel becomes too large to obtain a good display. Therefore, the difference is desirably about 0.2 to 1.0 μm. In other words, it is desirable that the difference is about 4% or more and 20% or less with respect to the thicknesses 53R and 53G of the liquid crystal layer 4 of red pixels and green pixels. That is, it is desirable that the thickness 53B of the liquid crystal layer 4 of the blue pixel is about 104% to 120% of the thickness 53R, 53G of the liquid crystal layer 4 of the red pixel and the green pixel.
[0057]
After producing the liquid crystal cell 101 as described above, a negative retardation film 14a, a negative uniaxial retardation film 12a, a positive uniaxial retardation film 15, and an analyzer 13 are formed on the upper surface of the liquid crystal cell 101. The liquid crystal display element 100 was produced by sequentially laminating the negative retardation film 14a, the negative uniaxial retardation film 12b, and the polarizer 16 on the lower surface of the liquid crystal cell 101 in this order.
[0058]
The in-plane direction retardation Re of the negative retardation films 14a and 14b described above is 36 nm when calculated by the following equation (1), and the in-plane direction retardation Re of the positive uniaxial retardation film 15 is the same. It was 150 nm. Further, the thickness direction retardation Rth of the negative uniaxial retardation films 12a and 12b was 175 nm.
[0059]
Re = (nx−ny) × d (1)
Rth = ((nx + ny) / 2−nz) × d (2)
Here, nx and ny indicate the refractive index in the in-plane direction, nz indicates the refractive index in the thickness direction, and d indicates the thickness of the liquid crystal layer.
[0060]
In this example, the phase difference Δnd of the liquid crystal layer 4 defined by the product of the thickness d of the liquid crystal layer 4 and the refractive index anisotropy Δn of the liquid crystal molecules 201 was set to 0.73 μm.
[0061]
FIG. 7 is a block diagram showing a configuration of a liquid crystal display device including the liquid crystal display element 100 manufactured as described above. In FIG. 7, a liquid crystal display device 1 is a TFT (Thin Film Transistor) type including the above-described liquid crystal display element 100, blocks 32, 33, and 34, and a backlight (not shown) that emits white light. belongs to. Referring also to FIG. 2, the lower substrate 103 is a TFT substrate. On the TFT substrate, gate lines 36 and source lines 37 are arranged in a matrix, and pixel electrodes 39 and switching elements 38 are formed for each pixel defined by the gate lines 36 and the source lines 37. ing. The gate line 36 and the source line 37 are driven by the gate driver 33 and the source driver 34, respectively, and the gate driver 33 and the source driver 34 are controlled by the controller 22.
[0062]
In the liquid crystal display device 1 configured as described above, the controller 22 outputs control signals to the gate driver 33 and the source driver 34 in accordance with an image signal 35 input from the outside. In this case, the gate driver 33 outputs a gate signal to the gate line 36 to sequentially turn on the switching elements 38 of each pixel, while the source driver 34 sends an image signal to each pixel through the source line 37 in accordance with the timing. Each is input to the pixel electrode 39. As a result, the liquid crystal molecules 201 are modulated, the transmittance of light emitted from the backlight is changed, and an image corresponding to the image signal 35 appears in the eyes of the user observing the liquid crystal display device 1.
[0063]
FIG. 8 is a graph showing the voltage-luminance characteristics of the red, green, and blue pixels of the liquid crystal display element 100 when an image is displayed using the liquid crystal display device 1 described above. As shown in FIG. 8, the luminance is minimum when the applied voltage is 7.2 V in the case of a blue pixel, and the applied voltage is 7.1 V in the case of a red pixel and a green pixel. Note that the voltage required for white display is determined by the voltage at which the bend orientation reversely changes to the splay orientation. In the case of the liquid crystal display element 100 of this example, the reverse transition voltage was 2.2 V in all of the red pixel, the green pixel, and the blue pixel.
[0064]
FIG. 9 is a graph showing the spectral spectrum distribution of transmitted light in the normal direction of the liquid crystal display element 100 when black display is performed. The color coordinates at this time were (0.3120, 0.3227). As described above, when the color coordinates are approximately (0.3, 0.3), the best achromatic display with no color is obtained. Therefore, in this embodiment, a good black display can be realized. I understand that.
[0065]
As described above, in this embodiment, the phase difference Δnd is set to 0.73 μm, but it goes without saying that the phase difference Δnd is not limited to this value.
[0066]
[Modification 1]
Next, a modification of the present embodiment will be described. As described above, the liquid crystal display device according to Example 1 realized color display by the color filter method. On the other hand, the liquid crystal display device according to the modified example 1 performs color display by a field sequential color method.
[0067]
FIG. 10 is a cross-sectional view schematically illustrating an outline of a configuration example of a liquid crystal display device according to the first modification. As shown in FIG. 10, the liquid crystal display element 100 included in the liquid crystal display device according to the first modification has the liquid crystal display element 100 according to the first embodiment, except that the three color filters 51R, 51G, and 51B are not provided. It is configured in the same way. Therefore, in FIG. 10, only the configuration of the liquid crystal cell 101 included in the liquid crystal display element 100 included in the liquid crystal display device according to the first modification is illustrated, and the same reference numerals as those in the first embodiment are given.
[0068]
The liquid crystal display device including the liquid crystal display element 100 is of the TFT type as in the case of the first embodiment. However, unlike the case of the first embodiment, the liquid crystal display device is not a backlight that emits white light, but 3 on the entire surface. A backlight 150 in which colored light emitting diodes (hereinafter referred to as LEDs) are spread at a predetermined interval is provided below the liquid crystal display element 100. Here, in the liquid crystal display element 100 and the backlight 150, the red pixel, the green pixel, and the blue pixel of the liquid crystal display element 100 correspond to the red LED 151R, the green LED 151G, and the blue LED 151B of the backlight 150, respectively. Is arranged. Then, color display is realized by emitting the LEDs of each color of the backlight 150 in a time-sharing manner in the order of red, green, and blue.
[0069]
When black display was performed with the liquid crystal display device configured as described above, blue coloring could be reduced as in the case of Example 1. As a result, a good black display could be realized.
[0070]
[Comparative Example 1]
In the liquid crystal display element included in the liquid crystal display device according to Comparative Example 1, the thickness of the liquid crystal layer corresponding to each of the red pixel, the green pixel, and the blue pixel is the same. Other configurations are the same as those of the liquid crystal display element 100 according to the first embodiment, and thus the description thereof is omitted.
[0071]
Image display was performed using the liquid crystal display device according to Comparative Example 1 as described above, and the voltage-luminance characteristics of the red, green, and blue pixels of the liquid crystal display element were examined in the same manner as in Example 1. As a result, the luminance was minimized when the applied voltage was 6.7 V for the blue pixel, and when the applied voltage was 7.1 V for the red and green pixels.
[0072]
FIG. 11 is a graph showing the spectral spectrum distribution of transmitted light in the normal direction of the liquid crystal display device according to Comparative Example 1. The color coordinates at this time are (0.2035, 0.1607), and it can be seen that the black display is colored blue.
[0073]
  Reference Example 1 Reference Example 1 of the present inventionDisplays black by shifting the alignment direction of the liquid crystal molecules in the blue pixel for displaying blue and the alignment direction of the liquid crystal molecules in the red and green pixels for displaying red and green, respectively, by a predetermined angle. The liquid crystal display device which reduces blue coloring in the case of performing is shown.
[0074]
  FIG. 12 shows Reference Example 1It is sectional drawing which shows typically the structure of the liquid crystal cell with which the liquid crystal display element with which the liquid crystal display device which concerns on comprises is comprised. As shown in FIG. 12, in the liquid crystal cell 101, unlike the first embodiment, the lower substrate 103 has no recess, and the liquid crystal layer 4 in any of the red pixel, the green pixel, and the blue pixel has a thickness. Are the same. Since the other configuration is the same as that of the liquid crystal cell 101 in the first embodiment, the same reference numerals are given and description thereof is omitted. The configuration other than the liquid crystal cell 101 is the same as that of the liquid crystal display device according to the first embodiment described with reference to FIG.
[0075]
  Hereinafter, referring to FIG. 1 and FIG.Reference example 1A process for manufacturing the liquid crystal display element 100 included in the liquid crystal display device according to the present invention will be described. First, a polyimide alignment film paint LPP-JP265CP (solvent: cyclopentanone) manufactured by Rolic is applied to the lower surface of the transparent electrode 2 and the upper surface of the transparent electrode 7 by spin coating, and baked at 150 ° C. for 1 hour. Then, the alignment films 3 and 6 were formed by curing.
[0076]
The alignment films 3 and 6 thus formed were irradiated with linearly polarized ultraviolet light at an angle of 30 degrees with respect to the normal direction of the substrate for 10 minutes (the irradiation energy on the substrate was 0.50 J). / Cm²Met). FIG. 13 is an explanatory diagram showing the polarization direction of the ultraviolet light applied to the regions corresponding to the red, green, and blue pixels. As shown in FIG. 13, the polarization direction 56R of the ultraviolet light applied to the region 55R corresponding to the red pixel in the alignment films 3 and 6 is the same as the polarization direction 56G of the ultraviolet light applied to the region 55G corresponding to the green pixel. It is. On the other hand, the polarization direction 56B of the ultraviolet light applied to the region 55B corresponding to the blue pixel in the alignment films 3 and 6 forms an angle of 5 degrees with respect to the polarization directions 56R and 56G. Therefore, the alignment direction of the liquid crystal molecules 201 related to the red pixel and the green pixel and the alignment direction of the liquid crystal molecules 201 related to the blue pixel are different at an angle of 5 degrees.
[0077]
Note that the closer the alignment direction of the liquid crystal molecules 201 related to the blue pixel is to the transmission axis of the polarizing plate 16, the lower the blue coloring in the case of performing black display. However, on the other hand, display characteristics such as viewing angle characteristics and luminance are deteriorated. Therefore, the angle formed by the polarization directions 56R and 56G and the polarization direction 56B, that is, the angle formed by the alignment direction of the liquid crystal molecules 201 related to the red and green pixels and the alignment direction of the liquid crystal molecules 201 related to the blue pixels is 2 degrees or more. About 30 degrees or less, preferably about 5 degrees or more and 10 degrees or less are appropriate.
[0078]
Next, using a spacer (not shown) manufactured by Sekisui Fine Chemical Co., Ltd. and a struct bond 352A which is a sealing resin manufactured by Mitsui Toatsu Chemical Co., Ltd., the distance between the upper substrate 102 and the lower substrate 103, that is, liquid crystal The upper substrate 102 and the lower substrate 103 were bonded so that the thickness of the layer 4 was 5.8 μm. Then, a liquid crystal cell 101 was manufactured by injecting liquid crystal MT-5585 (refractive index anisotropy Δn = 0.140) into the liquid crystal layer 4 by a vacuum injection method. At this time, the pretilt angle of the liquid crystal molecules at the interface between the alignment films 3 and 6 was about 2 degrees.
[0079]
After the liquid crystal cell 101 is manufactured as described above, as shown in FIG. 1, a negative retardation film 14a, a negative uniaxial retardation film 12a, and a positive uniaxial retardation are formed on the upper surface of the liquid crystal cell 101. A film 15 and an analyzer 13 are sequentially stacked, and a negative retardation film 14a, a negative uniaxial retardation film 12b, and a polarizer 16 are sequentially stacked on the lower surface of the liquid crystal cell 101, whereby the liquid crystal according to the second embodiment. A display element 100 was produced.
[0080]
The optical elements described above were arranged as shown in FIG. However, alignment processing directions 17 and 18 in FIG. 3 represent alignment processing directions in regions corresponding to red pixels and green pixels. The alignment processing direction in the region corresponding to the blue pixel is as described above with reference to FIG.
[0081]
The phase difference Re in the in-plane direction of the negative retardation films 14a and 14b described above is 39 nm when calculated by the above-described equation (1), and the phase difference Re in the in-plane direction of the positive uniaxial retardation film 15 is Similarly, it was 150 nm. Moreover, the retardation Rth in the thickness direction of the negative uniaxial retardation films 12a and 12b described above was also 220 nm.
[0082]
  Also,Reference example 1Then, the phase difference Δnd of the liquid crystal layer 4 defined by the product of the thickness d of the liquid crystal layer 4 and the refractive index anisotropy Δn of the liquid crystal molecules 201 was set to 0.81 μm.
[0083]
In the same manner as in Example 1, image display was performed using a liquid crystal display device including the liquid crystal display element 100 manufactured as described above. As a result, the luminance of the liquid crystal display element 100 was minimized when the applied voltage was 6.4 V for the blue pixel, and when the applied voltage was 7.0 V for the red pixel and the green pixel. The color coordinates when black display was performed by applying these voltages to each pixel were (0.2853, 0.3088). Therefore, a satisfactory black display could be realized.
[0084]
  By the way, bookReference exampleThen, as described above, the alignment process is performed in a direction different from the alignment direction in the region corresponding to the red pixel and the green pixel with respect to the region corresponding to all the blue pixels. Only a part may be targeted. That is, for example, a different alignment process may be performed only on a region corresponding to a blue pixel near the center of the screen. Usually, the user is gazing at the central part of the screen and often does not pay attention to the peripheral part away from the central part. Therefore, when black display is performed, it is considered practically sufficient if the blue coloring is reduced near the center.
[0085]
  BookReference exampleIn this case, the same modification example as that of the modification example 1 described above can be realized. That is, a liquid crystal display element configured in the same manner as the liquid crystal display element in Example 2 except that no color filter is provided, and a backlight having LEDs that emit light of the three primary colors are provided. A good black display can be obtained by using a field sequential type liquid crystal display device.
[0086]
  (Reference Example 2)
  BookReference example 2Is different from the pretilt angle of liquid crystal molecules corresponding to blue pixels for displaying blue and the pretilt angles of liquid crystal molecules corresponding to red and green pixels for displaying red and green, respectively. The liquid crystal display device which reduces blue coloring in the case of performing display is shown.
[0087]
  Reference example 2The configuration of the liquid crystal cell included in the liquid crystal display element included in the liquid crystal display device according toReference example 1Since this is the same as that of FIG. 12 and as shown in FIG. The configuration other than the liquid crystal cell is the same as that of the liquid crystal display element included in the liquid crystal display device according to the first embodiment described with reference to FIG.
[0088]
  Hereinafter, referring to FIG. 1 and FIG.Reference example 2A process for manufacturing a liquid crystal display element included in the liquid crystal display device according to the present invention will be described. First, a polyimide alignment film paint JALS-614 manufactured by JSR Corporation was applied to the lower surface of the transparent electrode 2 and the upper surface of the transparent electrode 7 by spin coating, and baked at 180 ° C. for 1 hour, followed by curing to align the alignment film 3, 6 was formed.
[0089]
The alignment films 3 and 6 thus formed are rubbed using a rayon rubbed cloth. FIG. 14 is an explanatory diagram showing the direction in which the rubbing process is performed in this case. As shown in FIG. 14, the regions 55R, 55G, and 55B corresponding to the red pixel, green pixel, and blue pixel in the alignment films 3 and 6 are rubbed in the same direction.
[0090]
The alignment films 3 and 6 are exposed using a mask to control the amount of ultraviolet light applied to the areas corresponding to the red, green, and blue pixels, and their surfaces. Change state. Thereafter, using a spacer (not shown) manufactured by Sekisui Fine Chemical Co., Ltd. and a struct bond 352A which is a sealing resin manufactured by Mitsui Toatsu Chemical Co., Ltd., the distance between the upper substrate 102 and the lower substrate 103, that is, the liquid crystal layer The upper substrate 102 and the lower side 103 were bonded together so that the thickness of 4 was 5.4 μm. Then, a liquid crystal cell 101 was manufactured by injecting liquid crystal MT-5585 (refractive index anisotropy Δn = 0.140) into the liquid crystal layer 4 by a vacuum injection method. At this time, the pretilt angles of the liquid crystal molecules in each of the red pixel, the green pixel, and the blue pixel were 5.5 degrees, 5.5 degrees, and 0.8 degrees.
[0091]
Note that the value that the pretilt angle of the liquid crystal molecules in each pixel can take is not limited to the above value, but the difference between the pretilt angle of the liquid crystal molecules in the blue pixel and the pretilt angle of the liquid crystal molecules in the red pixel and the green pixel is different. If it is not suitable, blue coloring cannot be reduced while maintaining good display characteristics. Therefore, the pretilt angle of the liquid crystal molecules in the blue pixel should be 5% to 50%, preferably 10% to 40%, of the pretilt angle of the liquid crystal molecules in the red pixel and the green pixel.
[0092]
After the liquid crystal cell 101 is manufactured as described above, as shown in FIG. 1, a negative retardation film 14a, a negative uniaxial retardation film 12a, and a positive uniaxial retardation are formed on the upper surface of the liquid crystal cell 101. The film 15 and the analyzer 13 are sequentially stacked, and the negative retardation film 14a, the negative uniaxial retardation film 12b, and the polarizer 16 are sequentially stacked on the lower surface of the liquid crystal cell 101, whereby the liquid crystal according to the third embodiment. A display element 100 was produced. In addition, each optical element mentioned above was arrange | positioned as shown in FIG.
[0093]
The phase difference Re in the in-plane direction of the negative retardation films 14a and 14b described above is 34 nm when calculated by the above-described equation (1), and the phase difference Re in the in-plane direction of the positive uniaxial retardation film 15 is Similarly, it was 100 nm. Moreover, the thickness direction retardation Rth of the negative uniaxial retardation films 12a and 12b described above was also 200 nm.
[0094]
  Also bookreferenceIn the example, the phase difference Δnd defined by the product of the thickness d of the liquid crystal layer 4 and the refractive index anisotropy Δn of the liquid crystal molecules 201 is set to 0.759 μm.
[0095]
In the same manner as in Example 1, image display was performed using a liquid crystal display device including the liquid crystal display element 100 manufactured as described above. As a result, the luminance of the liquid crystal display element 100 is minimum when the applied voltage is 6.8V for the blue pixel, the same 6.9V for the green pixel, and the same 7.0V for the red pixel. became. The color coordinates when black display was performed by applying these voltages to each pixel were (0.2978, 0.3013). Therefore, a satisfactory black display could be realized.
[0096]
As described above, the liquid crystal molecules in the blue pixel have a lower pretilt angle than in the case of the red pixel and the green pixel. Therefore, in the normally white mode, the voltage-transmittance characteristics shift to the high voltage side in the case of blue pixels compared to the case of the pretilt angles that are the same as the pretilt angles of the red and green pixels. When a voltage is applied, the phase difference of the liquid crystal layer 4 in a blue pixel having a low pretilt angle increases, so that the phase difference is comparable to that of a negative phase difference film, and the blue color when black display is performed Can be reduced.
[0097]
  BookReference exampleIn this case, the same modification example as that of the modification example 1 described above can be realized. That is, it has a liquid crystal display element configured similarly to the liquid crystal display element included in the liquid crystal display device according to the second embodiment except that no color filter is provided, and an LED that emits light of each of the three primary colors. By using a field sequential type liquid crystal display device provided with a backlight, a good black display can be obtained.
[0098]
  (Reference Example 3)
  Reference example 3Shows a liquid crystal display device that reduces blue coloring in black display by adopting liquid crystal molecules having a relatively large refractive index anisotropy Δn and relatively reducing the phase difference Δnd of the liquid crystal layer. is there.
[0099]
  Reference Example 3The configuration of the liquid crystal cell included in the liquid crystal display element included in the liquid crystal display device according toReference example 1Since this is the same as that of FIG. 12 and as shown in FIG. The configuration other than the liquid crystal cell is the same as that of the liquid crystal display element included in the liquid crystal display device according to the first embodiment described with reference to FIG.
[0100]
  Hereinafter, referring to FIG. 1 and FIG.Reference example 3A process for manufacturing the liquid crystal display element 100 included in the liquid crystal display device according to the present invention will be described. First, an alignment film coating SE-7492 manufactured by Nissan Chemical Industries, Ltd. is applied to the lower surface of the transparent electrode 2 and the upper surface of the transparent electrode 7 by spin coating, respectively, baked at 180 ° C. for 1 hour, and then cured to align the alignment films 3 and 6. Formed.
[0101]
The alignment films 3 and 6 thus formed were rubbed in accordance with the alignment processing directions 17 and 18 shown in FIG. Next, using the spacer 5 manufactured by Sekisui Fine Chemical Co., Ltd. and the struct bond 352A which is a sealing resin manufactured by Mitsui Toatsu Chemical Co., Ltd., the distance between the upper substrate 102 and the lower substrate 103, that is, the thickness of the liquid crystal layer 4 The upper substrate 102 and the lower side 103 were bonded to each other so as to be 5.0 μm. Then, a liquid crystal cell 101 was manufactured by injecting a liquid crystal material MJ97206 (refractive index anisotropy Δn = 0.160) manufactured by Merck to the liquid crystal layer 4 by a vacuum injection method.
[0102]
After the liquid crystal cell 101 is manufactured as described above, as shown in FIG. 1, a negative retardation film 14a, a negative uniaxial retardation film 12a, and a positive uniaxial retardation are formed on the upper surface of the liquid crystal cell 101. The film 15 and the analyzer 13 are sequentially stacked, and the negative retardation film 14a, the negative uniaxial retardation film 12b, and the polarizer 16 are sequentially stacked on the lower surface of the liquid crystal cell 101, whereby the liquid crystal according to the third embodiment. A display element 100 was produced. In addition, each optical element mentioned above was arrange | positioned as shown in FIG.
[0103]
The phase difference Re in the in-plane direction of the negative retardation films 14a and 14b described above is 36 nm when calculated by the above-described equation (1), and the phase difference Re in the in-plane direction of the positive uniaxial retardation film 15 is Similarly, it was 150 nm. Further, the retardation Rth in the thickness direction of the negative uniaxial retardation films 12a and 12b described above was 220 nm as determined by the above-described formula (2).
[0104]
  Also bookreferenceIn the example, the phase difference Δnd of the liquid crystal layer 4 defined by the product of the thickness d of the liquid crystal layer 4 and the refractive index anisotropy Δn of the liquid crystal molecules 201 was set to 0.80 μm.
[0105]
In the same manner as in Example 1, image display was performed using a liquid crystal display device including the liquid crystal display element 100 manufactured as described above. As a result, the luminance of the liquid crystal display element 100 is minimum when the applied voltage is 6.8V for the blue pixel, the same 6.9V for the green pixel, and the same 7.0V for the red pixel. became. The color coordinates when black display was performed by applying these voltages to each pixel were (0.2978, 0.3013). Therefore, a satisfactory black display could be realized.
[0106]
  FIG. 15 is a graph for comparing wavelength dispersion characteristics of retardation of liquid crystal layers when liquid crystal materials having different refractive index anisotropy Δn are used. In FIG. 15, reference numeral 41 denotes a book.Reference exampleThe phase difference of the liquid crystal layer 4 when the refractive index anisotropy Δn of the liquid crystal material is 0.160 and the phase difference Δnd is 0.80 μm is shown. On the other hand, 42 indicates the phase difference of the liquid crystal layer when the refractive index anisotropy Δn of the liquid crystal material is 0.140 (MT-5583) and the phase difference Δnd is 0.756 μm. As shown in FIG. 15, when the refractive index anisotropy Δn of the liquid crystal material is larger and the phase difference Δnd is smaller, the wavelength dispersion characteristic is steeper in the blue wavelength region. Therefore, since it becomes close to the wavelength dispersion characteristic of the retardation of the negative retardation film (see FIG. 25), it is possible to reduce blue coloring when black display is performed.
[0107]
By the way, as described above, even if it is desirable that the refractive index anisotropy Δn of the liquid crystal material is relatively large and the phase difference Δnd is relatively small, it is determined what range is actually acceptable. It is difficult. Therefore, the present inventors have prepared an experiment in which a plurality of combinations of the refractive index anisotropy Δn and the phase difference Δnd of the liquid crystal material are prepared and the amount of blue coloring is produced when black display is performed. went. The results are summarized in FIG.
[0108]
As shown in FIG. 16, when the refractive index anisotropy Δn of the liquid crystal material is 0.1431 or less, blue coloring was confirmed when black display was performed regardless of the value of the phase difference Δnd. Similarly, when the phase difference Δnd is 0.91 or more, blue coloration was confirmed when black display was performed regardless of the value of the refractive index anisotropy Δn of the liquid crystal material. When the refractive index anisotropy Δn of the liquid crystal material is 0.1502 or more and the phase difference Δnd is 0.8 μm or less, blue coloring is hardly recognized, and a good black display can be realized. did it. From this result, it can be determined that the case where the refractive index anisotropy Δn of the liquid crystal material is 0.15 or more and the phase difference Δnd is 0.8 μm or less is desirable.
[0109]
  BookReference exampleIn this case, the same modification example as that of the modification example 1 described above can be realized. That is, except that no color filter is providedReference example 1By using a field sequential type liquid crystal display device having a liquid crystal display element configured similarly to the liquid crystal display element according to the above and a backlight having an LED that emits light of each of the three primary colors. Black display can be obtained.
[0110]
  (Reference Example 4)
  Reference example 4Shows a liquid crystal display device that reduces blue coloring in black display by setting the refractive indexes nx, ny, and nz of the retardation film to 1.5 or less.
[0111]
  Reference example 4The configuration of the liquid crystal cell included in the liquid crystal display element included in the liquid crystal display device according toReference example 1Since this is the same as that of FIG. 12 and as shown in FIG. The configuration other than the liquid crystal cell is the same as that of the liquid crystal display element included in the liquid crystal display device according to the first embodiment described with reference to FIG.
[0112]
  Hereinafter, referring to FIG. 1 and FIG.Reference example 4A process for manufacturing the liquid crystal display element 100 included in the liquid crystal display device according to the present invention will be described.Reference example 3After the upper substrate 102 and the lower substrate 103 were bonded in the same manner as described above, the liquid crystal MT-5853 (refractive index anisotropy Δn = 0.140) was applied to the liquid crystal layer 4 of the substrate tube by vacuum injection. Was injected to prepare a liquid crystal cell 101.
[0113]
After the liquid crystal cell 101 is manufactured as described above, as shown in FIG. 1, a negative retardation film 14a, a negative uniaxial retardation film 12a, and a positive uniaxial retardation are formed on the upper surface of the liquid crystal cell 101. The film 15 and the analyzer 13 are laminated in this order, and the negative retardation film 14a, the negative uniaxial retardation film 12b, and the polarizer 16 are sequentially laminated on the lower surface of the liquid crystal cell 101, whereby the liquid crystal according to the fifth embodiment. A display element 100 was produced. In addition, each optical element mentioned above was arrange | positioned as shown in FIG.
[0114]
The negative uniaxial retardation films 12a and 12b described above are made of a triacetyl cellulose (TAC) film, and the retardation Rth in the thickness direction is 175 nm when calculated by the above-described formula (2). The negative uniaxial retardation films 12a and 12b have in-plane refractive indexes nx and ny and thickness-direction refractive indexes nz of nx = 1.48671, ny = 1.48671, nz = 1. 48612.
[0115]
The in-plane retardation Re of the negative retardation films 14a and 14b described above is 40 nm when calculated by the above-described equation (1), and the in-plane retardation of the positive uniaxial retardation film 15 is obtained. Re was also 150 nm.
[0116]
  Also bookreferenceIn the example, the phase difference Δnd of the liquid crystal layer 4 defined by the product of the thickness d of the liquid crystal layer 4 and the refractive index anisotropy Δn of the liquid crystal molecules 201 was set to 0.73 μm.
[0117]
In the same manner as in Example 1, image display was performed using a liquid crystal display device including the liquid crystal display element 100 manufactured as described above. As a result, the luminance of the liquid crystal display element 100 is minimum when the applied voltage is 6.0 V in the case of a blue pixel, 5.6 V in the case of a green pixel, and 5.6 V in the case of a red pixel. became. The color coordinates when black display was performed by applying these voltages to each pixel were (0.2878, 0.2995). Therefore, a satisfactory black display could be realized.
[0118]
  BookreferenceIn the example, the refractive indexes nx, ny, and nz of the negative uniaxial retardation films 12a and 12b made of a TAC film are 1.48771, 1.48671, and 1.48612, respectively, but are limited to this value. Of course not. At present, it is difficult to obtain a material having a refractive index smaller than 1.45. Therefore, it is desirable that the refractive index is 1.45 or more and 1.5 or less.
[0119]
  [Comparative Example 2]
  Reference example 4In the liquid crystal display element included in the liquid crystal display device according to the above, as described above, the negative uniaxial retardation films 12a and 12b are made of a TAC film. On the other hand, in the liquid crystal display element according to Comparative Example 2, the negative uniaxial retardation films 12a and 12b are made of a general discotic liquid crystal film based on triphenylmethane. In addition, about the other structure of the liquid crystal display element which concerns on the comparative example 2,Reference example 4Since this is the same as the case of, the description is omitted.
[0120]
The negative uniaxial retardation films 12a and 12b made of the above-described discotic liquid crystal film had a thickness direction retardation Rth of 175 nm according to the above equation (2). The negative uniaxial retardation films 12a and 12b have in-plane refractive indices nx and ny and thickness-direction refractive indices nz of nx = 1.66771, ny = 1.66771, nz = 1. It was 68612.
[0121]
Furthermore, the color coordinates in the normal direction at the time of black display obtained by applying the voltage described above to each pixel are (0.2023, 0.2512), and blue coloring occurs. I understand.
[0122]
  Mentioned aboveReference example 4As can be seen from a comparison between Comparative Example 2 and Comparative Example 2, a difference was observed in the occurrence of blue coloring depending on the difference between the negative uniaxial retardation films 12a and 12b.
[0123]
  [Reference Example 5]
  Reference example 4As described above, the negative uniaxial retardation film included in the liquid crystal display element included in the liquid crystal display device according to the present invention is composed of a TAC film.Reference Example 5In the liquid crystal display element included in the liquid crystal display device according to the above, the negative uniaxial retardation film is composed of a TAC film and a discotic liquid crystal film.
[0124]
FIG. 17 is a graph showing the wavelength dispersion characteristics of the phase difference of each optical element. In FIG. 17, 61 and 62 indicate the wavelength dispersion characteristics of the retardation of the TAC film and the wavelength dispersion characteristics of the retardation of the discotic liquid crystal film, respectively. Reference numerals 63 and 64 respectively denote the wavelength dispersion characteristics of the retardation of the negative uniaxial retardation film composed of the TAC film and the discotic liquid crystal film, and the wavelength dispersion characteristics of the retardation of the liquid crystal layer.
[0125]
As shown in FIG. 17, the retardation of the TAC film and the retardation of the discotic liquid crystal film have different wavelength dispersion characteristics, but the wavelength of the retardation of the negative uniaxial retardation film obtained by combining these films. The dispersion characteristic is close to the wavelength dispersion characteristic of the phase difference of the liquid crystal layer in the blue wavelength region. As can be seen from this, by combining the TAC film and the discotic liquid crystal film, it becomes possible to easily control the wavelength dispersion characteristic of the retardation of the negative uniaxial retardation film. The wavelength dispersion characteristic of the phase difference of the layer can be substantially matched in the blue wavelength region. As a result, it is possible to reduce the blue coloring that occurs when black display is performed.
[0126]
  Referring to FIGS. 1 and 12 together,Reference Example 5The liquid crystal display element included in the liquid crystal display device according to the above includes negative uniaxial retardation films 12a and 12b made of a film in which a TAC film and a discotic liquid crystal film are laminated. The in-plane direction retardation Re of the negative uniaxial retardation films 12a and 12b is 150 nm when calculated by the above-described equation (1), and the thickness direction retardation Rth is calculated by the above-described equation (2). When calculated, it was 190 nm. Further, the in-plane retardation Re of the negative retardation films 14a and 14b was 40 nm when calculated by the above-described equation (1).
[0127]
  Also bookreferenceIn the example, the phase difference Δnd of the liquid crystal layer 4 defined by the product of the thickness d of the liquid crystal layer 4 and the refractive index anisotropy Δn of the liquid crystal molecules 201 was set to 0.73 μm.
[0128]
In the same manner as in Example 1, image display was performed using a liquid crystal display device including the liquid crystal display element 100 manufactured as described above. As a result, the luminance of the liquid crystal display element 100 is minimum when the applied voltage is 5.9V for the blue pixel, the same 6.4V for the green pixel, and the same 6.3V for the red pixel. became. The color coordinates when black display was performed by applying these voltages to each pixel were (0.3133, 0.3187). Therefore, a satisfactory black display could be realized.
[0129]
  [Reference Example 6]
  Reference example 4As described above with reference to FIG. 1, the liquid crystal display element according to the liquid crystal display device includes negative retardation films 12a and 12b, negative uniaxial retardation films 14a and 14b, The uniaxial retardation film 15 is provided. When a plurality of films are stacked in this way, not only the configuration becomes complicated, but also the cost of the liquid crystal display element increases.
[0130]
  Therefore,Reference Example 6The liquid crystal display element included in the liquid crystal display device according to the present invention is configured such that a smaller number of retardation films are sufficient. FIG.Reference Example 6It is sectional drawing which shows typically the structure of the liquid crystal display element which concerns on. As shown in FIG.Reference Example 6The liquid crystal display element 100 included in the liquid crystal display device according to the invention has a liquid crystal cell 101, and a negative retardation film 14 a, a biaxial retardation film 71 a, and an analyzer 13 are provided on the upper surface of the liquid crystal cell 101. They are stacked in order. Further, on the lower surface of the liquid crystal cell 101, a negative retardation film 14b, a biaxial retardation film 71b, and a polarizer 16 are sequentially laminated. The slow axes of the biaxial retardation films 71a and 71b are arranged so as to be in the same direction as the transmission axes of the analyzer 13 and the polarizer 16, respectively.
[0131]
  As is clear when comparing FIG. 1 and FIG.referenceThe liquid crystal display element 100 included in the liquid crystal display device according to the example does not include the positive uniaxial film 15, but includes biaxial retardation films 71a and 71b instead of the negative uniaxial retardation films 12a and 12b. ing. The positive uniaxial film 15 is a film necessary for suppressing leakage light, but the liquid crystal display element 100 according to Reference Example 6 includes the biaxial retardation films 71a and 71b, whereby the leakage is prevented. Light suppression can be achieved.
[0132]
The biaxial retardation films 71a and 71b are made of a TAC film, and the retardation Re in the in-plane direction is 100 nm when calculated by the above formula (1), and the retardation Rth in the thickness direction is It was 200 nm when calculated | required by Formula (2) mentioned above. Further, the in-plane retardation Re of the negative retardation films 14a and 14b was 36 nm as determined by the above-described formula (1).
[0133]
  Also bookreferenceIn the example, the phase difference Δnd of the liquid crystal layer 4 defined by the product of the thickness d of the liquid crystal layer 4 and the refractive index anisotropy Δn of the liquid crystal molecules 201 was set to 0.78 μm.
[0134]
Then, as in the case of Example 1, image display was performed using a liquid crystal display device including the liquid crystal display element 100 described above. As a result, the luminance of the liquid crystal display element 100 is minimum when the applied voltage is 6.7V in the case of the blue pixel, is also 7.1V in the case of the green pixel, and is 7.1V in the case of the red pixel. became. The color coordinates when black display was performed by applying these voltages to each pixel were (0.2871, 0.2947). Therefore, a satisfactory black display could be realized.
[0135]
  BookReference exampleIn this case, the same modification example as that of the modification example 1 described above can be realized. That is, except that no color filter is providedReference example 1By using a field sequential type liquid crystal display device having a liquid crystal display element configured similarly to the liquid crystal display element according to the above and a backlight having an LED that emits light of each of the three primary colors. Black display can be obtained.
[0136]
  (Reference Example 7)
  Reference Example 7 is a liquid crystal display that reduces blue coloring when black display is performed by making the amount of light emitted from the backlight substantially the same in each of the red, green, and blue wavelength regions. The apparatus is shown.
[0137]
  FIG. 19 shows the reference example 7.It is sectional drawing which shows typically the outline of the structural example of the liquid crystal display device which concerns. BookReference exampleThe liquid crystal display element 100 included in the liquid crystal display device according toReference example 1Since this is the same as FIG. 12 and is as shown in FIG.
[0138]
As shown in FIG. 19, the backlight 150 provided below the liquid crystal display element 100 includes a light source 151 configured to include a cold cathode tube. An interference filter 152 is disposed between the light source 151 and the liquid crystal display element 100. As shown in FIG. 19, the interference filter 152 is provided corresponding to the position of the blue pixel of the liquid crystal display element 100.
[0139]
The interference filter 152 is a band pass filter whose transmitted light has a wavelength of 450 nm. FIG. 20 is a graph showing the spectrum of light emitted from the light source 151, where (a) shows the spectrum when the interference filter 152 is provided, and (b) shows the spectrum when the interference filter 152 is not provided. It is a graph to show. As shown in FIG. 20A, when the interference filter 152 is provided, the half-value width of the spectrum of the emitted light in the blue wavelength region is 30 nm or less. On the other hand, as shown in FIG. 20B, when the interference filter 152 is not provided, the half width is a larger value.
[0140]
As described above, by providing the interference filter 152, the half width of the spectrum of the emitted light in the blue wavelength region can be reduced to 30 nm or less as described above. As a result, each of red, green, and blue The amount of emitted light in the wavelength region can be made substantially the same. Thereby, when black display is performed with this liquid crystal display device, blue coloring can be reduced.
[0141]
  [Example2]
  FIG. 21 shows an example of this embodiment.2It is sectional drawing which shows the outline of the structural example of the liquid crystal display device which concerns on this. The liquid crystal display element 100 included in the liquid crystal display device according to the present embodiment is the same as that of the first modification and is as shown in FIG.
[0142]
  As shown in FIG. 21, the backlight 150 provided below the liquid crystal display element 100 includes a light source in which LEDs that emit light of the three primary colors are spread at predetermined intervals. FIG. 22 is a graph showing an emission spectrum of an LED which is a light source included in the backlight 150 described above. Example2In the liquid crystal display device according to the above, color display is realized by emitting the LEDs of the respective colors of the backlight 150 in a time division manner in the order of red, green, and blue.
[0143]
  Example of such a field sequential color system2As a result of performing black display with the liquid crystal display device according to the above, it was possible to reduce blue coloring.
[0144]
By the way, as a light source with which the backlight 150 is provided, it is also possible to use an electroluminescent light emitting element (henceforth EL) instead of LED. FIG. 23 is a graph showing an emission spectrum of EL which is a light source included in the backlight 150 described above. As described above, when EL was used as the light source, the black display was performed in the same manner, and as a result, blue coloring could be reduced.
[0145]
  The above-described embodiment2However, it is needless to say that color display can be performed by the color filter method similarly to the case of the reference example 7 using the LED or EL that emits white light.
[0146]
As described above, the liquid crystal display device according to the present invention can reduce blue coloring that occurs when black display is performed. These liquid crystal display devices can be applied to various products. That is, it can be applied to, for example, a liquid crystal television, a liquid crystal monitor, or a liquid crystal display of a mobile phone.
[0147]
【The invention's effect】
As described above in detail, according to the liquid crystal display device of the present invention, it is possible to reduce the blue coloring that occurs when black display is performed, and to realize good black display.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing a configuration of a liquid crystal display element included in a liquid crystal display device according to Embodiment 1 of the present invention.
FIG. 2 is a diagram schematically showing a configuration of a liquid crystal cell included in a liquid crystal display element included in the liquid crystal display device according to Embodiment 1 of the present invention, in which (a) is a cross-sectional view of the liquid crystal cell; b) is an enlarged view of a liquid crystal layer portion in the cross-sectional view.
FIG. 3 is a plan view of the liquid crystal display element showing the arrangement direction of each optical element included in the liquid crystal display element included in the liquid crystal display device according to Embodiment 1 of the present invention.
FIG. 4 is a diagram for explaining a process of forming a concave structure included in the liquid crystal display element included in the liquid crystal display device according to Embodiment 1 of the present invention;
FIG. 5 is a plan view of a photomask used for forming a recess.
FIG. 6 is a diagram for explaining a step of forming a recess included in the liquid crystal display element included in the liquid crystal display device according to Embodiment 1 of the present invention.
FIG. 7 is a block diagram showing a configuration of a liquid crystal display device according to Embodiment 1 of the present invention.
FIG. 8 is a graph showing voltage-luminance characteristics of a red pixel, a green pixel, and a blue pixel of the liquid crystal display device according to the first embodiment of the present invention.
FIG. 9 is a graph showing a spectral spectrum distribution of transmitted light in the normal direction of the liquid crystal display device according to Example 1 of Embodiment 1 of the present invention when black display is performed.
10 is a cross-sectional view schematically showing another configuration example of the liquid crystal display device according to Embodiment 1 of the present invention. FIG.
11 is a graph showing a spectral spectrum distribution of transmitted light in a normal direction of a liquid crystal display device according to Comparative Example 1. FIG.
FIG. 12 shows the present invention.Reference exampleIt is sectional drawing which shows typically the structure of the liquid crystal cell with which the liquid crystal display element with which the liquid crystal display device which concerns on comprises is comprised.
FIG. 13 is a diagram of the present invention.Reference exampleIn the liquid crystal display element with which the liquid crystal display device concerning this is equipped, it is explanatory drawing which shows the polarization direction of the ultraviolet light irradiated to the area | region corresponding to each pixel of a red pixel, a green pixel, and a blue pixel.
FIG. 14 shows the present invention.Reference exampleIt is explanatory drawing which shows the rubbing direction in the case of performing the rubbing process with respect to the alignment film which the liquid crystal display element with which the liquid crystal display device which concerns on comprises comprises.
FIG. 15 is a graph for comparing wavelength dispersion characteristics of retardation of liquid crystal layers when liquid crystal materials having different refractive index anisotropy Δn are used.
FIG. 16 is a diagram showing a relationship between a combination of refractive index anisotropy Δn and phase difference Δnd of a liquid crystal material and blue coloring generated when black display is performed.
FIG. 17 is a graph showing wavelength dispersion characteristics of optical elements included in the liquid crystal display element.
FIG. 18 shows the present invention.Reference exampleIt is sectional drawing which shows typically the structure of the liquid crystal display element with which the liquid crystal display device which concerns on is equipped.
FIG. 19 shows the present invention.Reference exampleIt is sectional drawing which shows the outline of the structural example of the liquid crystal display device which concerns on this.
FIG. 20 shows the present invention.Reference example4 is a graph showing a spectrum of light emitted from a light source 151 included in the liquid crystal display device according to FIG. 5A, where (a) is provided with an interference filter 152, and (b) is provided when the interference filter 152 is not provided. It is a graph which shows a spectrum, respectively.
FIG. 21 shows the present invention.Example 2It is sectional drawing which shows typically the outline of the other structural example of the liquid crystal display device which concerns on.
FIG. 22 shows the present invention.Example 2It is a graph which shows the spectral spectrum of LED which is a light source with which the backlight of the liquid crystal display device which concerns on is equipped.
FIG. 23 shows the present invention.Example 2It is a graph which shows the spectrum of EL which is a light source with which the backlight of the liquid crystal display device which concerns on is equipped.
FIG. 24 is a cross-sectional view schematically showing a configuration of a conventional OCB mode liquid crystal display element.
FIG. 25 is a graph showing wavelength dispersion characteristics of a phase difference in a normal direction of a liquid crystal layer related to a red pixel, a green pixel, and a blue pixel included in a conventional OCB mode liquid crystal display element.
[Explanation of symbols]
1, 8 glass substrate, 2, 7 transparent electrode, 3, 6 alignment film, 4 liquid crystal layer, 10 recess,
12a, 12b negative uniaxial retardation film, 13 analyzer,
14a, 14b negative retardation film, 15 positive uniaxial retardation film, 16 polarizer,
20 resist thin film, 51R red color filter, 51G green color filter,
51B Blue color filter, 52 light shielding film, 100 liquid crystal display element, 101 liquid crystal cell,
102 upper substrate, 103 lower substrate, 201 liquid crystal molecules

Claims (4)

A liquid crystal display element having a liquid crystal layer in which liquid crystal molecules forming bend alignment in image display are arranged, and at least one negative retardation plate for compensating for retardation of the liquid crystal layer In a liquid crystal display device that performs display by changing the transmittance of light for display of the liquid crystal display element by changing the retardation of the liquid crystal layer according to an image signal input from the outside,
The negative retardation plate is a retardation plate made of an optical medium having negative refractive index anisotropy in which main axes are arranged in a hybrid manner,
The liquid crystal display element has a plurality of red pixels for displaying red, green pixels for displaying green, and blue pixels for displaying blue, and the thickness of the liquid crystal layer related to the blue pixels is A liquid crystal display device characterized in that it is larger than the thickness of the liquid crystal layer relating to the red pixel and / or the green pixel.   2. The liquid crystal according to claim 1, wherein a difference between a thickness of the liquid crystal layer related to the blue pixel and a thickness of the liquid crystal layer related to the red pixel and / or the green pixel is 0.2 μm to 1.0 μm. Display device.     2. The liquid crystal display device according to claim 1, wherein a thickness of the liquid crystal layer related to the blue pixel is 104% to 120% of a thickness of the liquid crystal layer related to the red pixel and / or the green pixel.   An illumination device having a light source that emits light of each color of red, green, and blue, and an illumination device control unit that controls the illumination device so that the light source emits each color light in a time-sharing manner. 2. A liquid crystal display device according to 1.

Images