TWI361932B - Liquid crystal display device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a liquid crystal display device, and more particularly to a transmissive liquid display device having a liquid crystal including horizontal alignment (US) a liquid crystal layer of a molecule. [Prior Art] Regarding a vertical alignment mode liquid crystal display device having excellent display characteristics in a front view direction, such as a twisted nematic (TN) mode liquid crystal display device, it has been proposed to realize a wide viewing angle characteristic by applying a retardation film for compensating a viewing angle. Technology (for example, see Japanese Patent Application K〇KAI Publication No.). In addition, C proposes a technique for manufacturing a biaxial birefringent film, which can be applied to a liquid crystal display device, such as a super twisted nematic (STN) mode liquid crystal display device ('J. See Japanese Patent Laid-Open KOKAI Publication No. 2005-181451 ).

In the past, there has been a demand for improving the display quality by, for example, improving the contrast and increasing the viewing angle of a liquid crystal display device in which a liquid crystal layer including horizontally aligned liquid crystal molecules is held between the substrates. On the other hand, there is always a need to reduce the thickness of the entire device and reduce costs. SUMMARY OF THE INVENTION The present invention has been conceived in view of the above problems. The display quality of the liquid crystal display device is low. The object of the present invention is to provide a liquid crystal display device having a good thickness reduction and cost reduction according to one aspect of the present invention, which comprises a package 127101-100H25.doc 1361932 3: - a liquid crystal display panel including horizontal alignment liquid crystal The liquid crystal layer of the molecule is held between a first substrate and a second substrate disposed opposite to each other; a first optical element is disposed on one of the outer surfaces of the liquid crystal display panel and includes a first a polarizing plate, a first phase retarding plate and a second phase retarding plate disposed between the first polarizing plate and the liquid crystal display panel, and a second optical component, which is disposed on the liquid crystal display panel a second polarizing plate on the other outer surface, wherein the first phase retarding plate imparts a predetermined retardation phase retardation plate to light of a predetermined wavelength, and wherein the nematic liquid crystal molecules are immobilized into the isotropic column The liquid crystal molecules are mixed and aligned in a normal direction. The present invention can provide a liquid crystal display device having good display quality, which can achieve thickness reduction and cost reduction. Additional objects and advantages of the invention will be set forth in the description in the description. The objects and advantages of the invention may be realized and obtained by the <RTIgt; Embodiments of a liquid crystal of a specific embodiment

Counter-substrate (second substrate) CT opposite to the board AR, and holding on the array substrate A display device according to one of the present invention will now be described with reference to the accompanying drawings. In this embodiment, a liquid crystal thin film is shown by selectively transmitting a backlight to display a transmissive image 12710M001125.doc -6 -

1361932 » Liquid crystal layer LQ between I AR and counter substrate CT. Further, the liquid crystal display device includes a first optical element 〇D1 which is provided on one of the outer surfaces of the liquid crystal display panel LPN (ie, an outer surface of the array substrate AR opposite to the other outer surface facing the liquid crystal layer LQ) And a first optical element OD2 provided on the other outer surface of the liquid crystal display panel LPN (ie, an outer surface of the counter substrate CT opposite to the other outer surface facing the liquid crystal layer). Further, the liquid crystal display device includes a backlight unit BL' which illuminates the liquid crystal display panel 1PN from the side of the first optical element 01)1. The liquid crystal display panel LPN includes a plurality of display areas DSP for displaying an image. The display area DSP is composed of a plurality of pixels 配置 arranged in an mxn matrix. The array substrate AR is formed by using an insulating substrate 光 having a light transmissive property such as a glass plate or a quartz plate. Specifically, the array substrate AR includes the number (mXn) of pixel electrodes EP placed in the individual pixels, and the number n of scanning lines Υ (Υ1 to Υη) formed along the column direction of the pixel electrode EP in the display area DSP. a number m of signal lines X (X 1 to Xm) formed along the row direction of the pixel electrode 、, and a number of built-in areas (mXn) in a region including intersections between the scanning lines γ and the signal lines X in the individual pixels ρ χ Switch component W. Further, in the drive circuit region DCT near the display area DSP, the array substrate AR includes at least a portion of the scan line driver connected to the number n of scan lines γ and at least a signal line driver XD connected to the number „! Part of the sense line driver Yd continuously supplies the scan signal (drive signal) to the number n of scan lines γ ^ according to the control of the controller cnt ^ under the control of the controller CNT 'the signal line driver xd is by the scan signal 127101-100I125.doc 1361932, when one of the switching elements w of each column is turned on, the video signal (drive signal) is supplied to the signal line X of the number m. Therefore, the pixel electrode ep in each column is set to correspond to the supply via the associated switching element W. The pixel potential of the video signal. For example, 'each switching element W is an n-channel thin film transistor, and includes a semiconductor layer 12 placed on the insulating substrate 10. The semiconductor layer 12 can be formed by using, for example, polysilicon or amorphous germanium. In this embodiment, the semiconductor layer u is formed of polysilicon. The semiconductor layer 12 includes a source region 12S and a drain region 12D 'channel region 1 2C is interposed between the two. The semiconductor layer 12 is covered with a gate insulating film 14. The gate electrode WG of the switching element W is connected to an associated scanning line Y (or formed integrally with the scanning line Y). The WG and the scanning line γ are placed on the gate insulating film 14. The gate electrode WG and the scanning line γ are covered by the interlayer insulating film 16. The source electrode WS and the drain electrode WD of the switching element W are placed on the gate electrode. On the interlayer insulating film 16 on both sides of the WG, the source electrode ws is connected to an associated signal line X (or formed integrally with the signal line X), and contacts the source region 12S of the semiconductor layer 12. The electrode WD is connected to an associated pixel electrode EP (or formed integrally with the pixel electrode EP) and contacts the drain region 12D of the semiconductor layer 12. The source electrode WS, the drain electrode WD, and the signal line are covered with the organic insulating film 18. The pixel electrode EP is placed on the organic insulating film 18 and electrically connected to the gate electrode wd via a contact hole formed in the organic insulating film 18. The pixel electrode EP is formed of a light transmissive conductive material such as indium tin oxide. (IT〇). Adopt 127101-100H25.doc 136 1932 • The alignment film 20 covers the pixel electrode Ερβ placed in each associated pixel ρχ. On the other hand, the counter substrate CT is formed by using a light transmissive insulating substrate 30 such as a glass plate or a quartz plate. The substrate (: 1 includes a counter electrode 内 in the display area DSP. The counter electrode Ε is placed opposite to the pixel electrode ,, which is associated with a plurality of pixels ρ 。. The counter electrode is formed of a light transmissive conductive material, such as germanium. The counter electrode is covered with an alignment film 36. The color display type liquid crystal display device includes a color filter layer 34 provided on the inner surface of the liquid crystal display panel LPN associated with each pixel. In the example shown in Fig. 2, the color filter layer 34 is provided on the counter substrate CT. The color filter layer 34 is formed of a plurality of color colored resins such as red, blue, and green. A red resin, a blue resin, and a green resin are placed in association with the red pixel, the blue pixel, and the green pixel, respectively. The color filter layer 34 can be placed on the array substrate AR side. The individual pixels ρ 分割 are divided by a black matrix (not shown). The black matrix is placed φ in opposition to the line, for example, the scanning line γ, the signal line X, and the switching element W provided on the array substrate AR. When the counter substrate CT and the array substrate are placed in the opposite direction to form the alignment films 20 and 36, the spacers (for example, the column formed by the tree raft material) placed between the alignment film 2 and the magazine are not displayed. The spacers provide a predetermined gap. The liquid crystal layer LQ is composed of a liquid crystal composite including liquid crystal molecules, which is sealed in the gap between the alignment film 20 of the array substrate AR and the alignment film 36 of the counter substrate CT. In this embodiment, the liquid crystal layer LQ includes liquid crystal molecules 40 having a twist angle (horizontal alignment). 12710M00H25.doc 1361932 In a liquid crystal display device according to a specific embodiment of the present invention, as shown in Fig. 3, the first optical element OD1 and the second optical element 〇D2 control the polarization state of light passing therethrough. Specifically, the first optical element OD1 controls the polarization state of the light passing through the first optical element OD1 so that the light in the polarization state of the elliptical polarization (which is as close as possible to the linear polarization) can be incident on the liquid crystal layer LQ. Therefore, the polarization state of the backlight incident on the first optical element OD1 is converted to a predetermined polarization state when the backlight passes through the first optical element OD1. Next, the spent backlight from the first optical element OD1 enters the liquid crystal layer LQ while maintaining the predetermined polarization state. When a voltage for black display (black display voltage) is applied to the liquid crystal layer LQ, the polarization state of light incident on the liquid crystal display panel LPN is affected by the phase difference of the liquid crystal layer LQ and changes to a substantially linear polarization state. The second optical element OD2 controls the polarization state of the light passing through the second optical element 〇D2 so that light in a polarized state of linearly polarized light (or as close as possible to the linearly polarized sugar circularly polarized light) can be incident on the liquid crystal layer LQ. Therefore, the polarization state of the light incident on the second optical element 〇D2 is converted into a predetermined polarization state, that is, a linear polarization state, when the light passes through the second optical element OD2. In other words, the polarization state of the light having passed through the first optical element 〇D1 and the liquid crystal display panel LPN is substantially linearly polarized, and the ellipticity (=the short-axis direction amplitude Es/the long-axis direction amplitude Ep) is substantially equal to the second pass. The ellipticity of the light of the optical element OD2. In this case, the substantially linear polarizing system has a polarizing state of 〇 j or less, and a preferred system is 〇 2 or less. With this structure, the contrast in the normal direction of the LPN of the liquid crystal display panel can be improved, and the viewing angle can be increased. 12710M001125.doc •10· 1361932 The individual structural components are detailed below. The first optical element OD1 is configured to include a first polarizing plate 51, and a first phase retardation plate RF1 and a second phase retardation plate RF2 disposed between the first polarizing plate 51 and the liquid crystal display panel LPN. In the example shown in Fig. 3, the first phase retardation plate RF1 is placed between the first polarizing plate 51 and the liquid crystal display panel LPN (array substrate AR). The second phase retardation plate RF2 is placed between the first polarizing plate 5 i and the first phase retardation plate RF1. The second optical element OD2 is composed of a second polarizing plate 52. The first polarizing plate 51 and the second polarizing plate 52 used in this embodiment each have an absorption axis and a transmission axis which are perpendicular to each other in a plane perpendicular to the traveling direction of the light. Each of the polarizers extracts light having an oscillation plane in a direction parallel to one of the transmission axes, that is, light in a linearly polarized state, from light having an oscillation plane in a random direction. The first phase retardation plate RF1 used herein is a phase retardation plate having optical anisotropy. As shown in FIG. 4A, the first phase retardation plate RF1 includes a liquid crystal film layer 60 in which nematic liquid crystal molecules 61 having optical positive uniaxial refractive index anisotropy are solidified to a normal direction in the liquid crystal phase (ie, phase The thickness direction of the retardation plate is a state in which the alignment liquid crystal molecules are mixed. In the liquid crystal film layer 60, for example, in the vicinity of the interface on the side of the array substrate AR, the liquid crystal molecules 61A are aligned with the interface at a large inclination angle (i.e., aligned to the liquid crystal molecules 61A substantially perpendicular to the interface). On the other hand, in the vicinity of the interface on the side of the second phase retardation plate rf2, the liquid crystal molecules 61B are aligned with the interface at a small inclination angle (i.e., aligned to the liquid crystal molecules 61B substantially parallel to the interface). In short, in the liquid crystal display panel LPN, the alignment direction of the liquid crystal molecules on the array substrate AR side when applying a voltage of 127101 - 1001125.doc 11 1361932 is different from the mixing direction of the liquid crystal molecules included in the first phase retardation plate RF1 by 180. . . An NH film (manufactured by Nippon Oil Corporation) can be applied as the first phase retardation plate RF1. This liquid crystal film has a function of optically compensating for the retardation of the liquid crystal layer LQ, since the alignment of the liquid crystal molecules 40 included in the liquid crystal layer with the liquid crystal film corresponds to a phase retardation plate having a viewing angle increasing function, which varies depending on the viewing angle. Regarding the liquid crystal layer LQ, the alignment of the liquid crystal molecules 40 having refractive index anisotropy and the phase retardation plate having refractive index anisotropy is more according to the applied voltage. When the birefringence is described, the slow axis corresponds to the axis having a large refractive index. The fast axis corresponds to the axis with a smaller refractive index. It is assumed that the slow axis coincides with the oscillation plane of the special ray and the fast axis coincides with the oscillation plane of the ordinary ray. When the refractive index of the ordinary ray and the refractive index of the special ray are respectively (10) and ne, and the thickness of the liquid crystal layer LQ extending in the traveling direction of the ray is d, the retardation of the liquid crystal layer LQ is Δ n*d (nm)=(ne .d-no-d) (ie Δ n=ne-no) definition. Further, regarding the phase retardation plate, the main refractive index corresponding to three mutually perpendicular axes is used. If the main refractive index systems nx and ny corresponding to mutually perpendicular axes in the plane of the phase retardation plate, the main refractive index nz corresponding to the axis of the normal direction (ie, the thickness direction of the phase retardation plate) is nz, and the phase retardation plate thickness is d The front delay of the phase delay plate is defined by R = (nx - ny).d. Each of the first phase retardation plate RF1 and the second phase retardation plate RF2 included in the first optical element OD1 has a slow axis and a fast axis perpendicular to each other, and has a predetermined front retardation. Specifically, the first phase retardation plate RF1 has a function of a phase retardation plate in addition to the above-described viewing angle increasing function, which imparts a predetermined delay between 127101-100H25.doc 136, 1932 at a predetermined wavelength (for example, 550 nm). That is, the delay λ/m, in which the lanthanide wavelength, m is a positive number, 'the light components pass through the slow axis which is the director of the liquid crystal molecules 61 and the fast axis which is perpendicular to the slow axis. Further, the second phase retardation plate RF2 is a phase retardation plate that imparts a predetermined delay (i.e., delay λ/η, where 2 is a wavelength, and n is a positive number) between light components of a predetermined wavelength (for example, 550 nm). The components pass through the fast axis and the slow axis. ZEONOR (manufactured by OPTES) and ARTON (manufactured by JSR) can be applied to the second phase retardation plate RF2. In the first optical element OD1, the individual structural components are arranged such that the absorption axis 第一1 of the first polarizing plate 51, the in-plane slow axis D1 of the first phase retardation plate RF1, and the in-plane slow axis D2 of the second phase retardation plate RF2 have predetermined Angle relationship. Specifically, the second phase retardation ruler is placed on the first polarizing plate 51 so that the slow axis D2 of the second phase retardation plate RF2 and the absorption axis Α 1* of the first polarizing plate 51 are about 45°. The first phase retardation plate RF1 is placed on the second phase retardation plate RF2' such that the slow axis d1 of the first phase retardation plate RF1 and the slow axis D2 of the second phase retardation plate RF2 are about 90. . In the case where the first optical element 〇D1 is placed on the liquid crystal display panel LPN, the first optical element 〇〇1 is placed in a slow axis D丨 of the first phase retardation plate RF丨 having a viewing angle increasing function. The guide body of the liquid crystal molecules 40 parallel to the liquid crystal layer LQ (the rubbing direction of the alignment film 20 on the array substrate Ar side)' and the mixed alignment direction of the liquid crystal molecules 61 in the first phase retardation plate RF1 and the alignment film 2 on the array substrate AR side The direction of rubbing is opposite. Further, the 'second optical element 〇D2' places the second polarizing plate 52 such that its absorption axis A2 is perpendicular to (about 9 Å.) the absorption axis Ai of the first polarizing plate 51. 127101-1001125.doc 1361932 With this configuration, the first optical element OD1 has a function of switching to elliptically polarized light or substantially linearly polarized light having a predetermined ellipsometric ratio, and a function of increasing the viewing angle. Further, the 'second optical element 〇D2 has a function of switching to a substantially linear polarization whose ellipticity is substantially equal to the ellipticity of the light having passed through the first optical element 001 and the liquid crystal display panel lpn. Specifically, the birefringent material forming the phase retardation plate has a characteristic that the main refractive index of the birefringent material depends on the wavelength of the light. Accordingly, the retardation R of the phase retardation plate depends on the wavelength of the passing light. Therefore, as described above, by using the first optical element OD1' in which at least two phase retardation plates are combined, the wavelength dependence of the delay R can be alleviated, and a predetermined delay can be imparted in all wavelength ranges for color display and The desired polarization state is obtained. Specifically, the backlight from the first optical element 〇D1 is converted into substantially linear polarization 'and incident on the liquid crystal layer 1 (assuming that the long-axis direction of the substantially linear polarization is parallel to the X-axis. In the liquid crystal layer Lq The substantial linear polarization that has entered the liquid crystal layer Lq when no voltage is applied (or when a low voltage is applied) imparts a delay of λ/2. Therefore, 'the light from the liquid crystal layer Lq is converted to linearly polarized light, which is perpendicular to the liquid crystal layer. Substantially linearly polarized. In short, the plane of oscillation of the linearly polarized light is parallel to the Υ axis, which is perpendicular to the X axis. Therefore, by applying the second polarizing plate 52 having the absorption axis parallel to the χ axis to the second optical element OD2 It is possible to transmit linear polarization from the liquid crystal layer LQ at a higher transmittance (&quot;white display&quot;) without using some other phase retardation plate. On the other hand, in the liquid crystal layer LQ, when voltage is applied ( Or substantially at the time of applying a high voltage, the substantially linear polarization incident on the liquid crystal layer LQ gives a substantially zero delay. Therefore, the light emitted from the liquid crystal layer LQ remains equal to the 127101-1001125.doc • 14 · 136.1932 substantially linearly polarized light that has just entered the liquid crystal layer. a polarization state of the polarized state. In short, the substantially linearly polarized oscillation plane is parallel to the axis. Therefore, by applying the second polarizing plate 52 having the absorption axis parallel to the X axis to the second optical element OD2, Linear polarized light from the liquid crystal layer LQ is absorbed at a higher absorption ratio (&quot;black display&quot;) without using some other phase retardation plate. As described above, since the second optical element is only composed of the second polarizing plate 52 Composition without using a phase retardation plate, thickness reduction and cost reduction can be achieved, and good optical characteristics can be obtained. Next, regarding the method for obtaining good optical characteristics, specifically, optical compensation when black display is shown, The front side delay r(rF1) of the first phase retardation plate RF1 in the optical element 〇D1 and the front side delay R(RF2) of the second phase delay plater ^ and the residual delay r(Lq) of the liquid crystal layer LQ in the black display The relationship between the residual retardation R(LQ) of the liquid crystal layer LQ is now explained. In the case where the voltage of the black display is applied to the liquid crystal layer (&quot;black display voltage&quot;), it is positioned in the middle portion away from the substrate interface (,, middle The liquid crystal molecules in the plane ") are aligned such that their long axis directions are substantially parallel to the direction of the electric field. Therefore, the front retardation of the midplane of the liquid crystal layer LQ is regarded as substantially zero (nm). However, alignment is performed near the substrate interface. The liquid crystal molecules 4 are affected by the alignment limiting force (&quot;anchoration) of the interface, the liquid crystal molecules 40 have a low voltage response, and the liquid crystal molecules 40 maintain a substantially initial alignment state. Accordingly, the liquid crystal layer substrate interface is nearby The front side delay does not become zero (nm). Therefore, even if a sufficiently high black display voltage is applied to the liquid crystal layer LQ to realize black display, the front retardation remains in the liquid crystal layer • LQ due to the mosquito shadow f at the substrate interface . This is commonly referred to as &quot;residual delay&quot;. 12710M001125.doc • 15-1361932 In this embodiment, (1) each of the liquid crystal layer LQ, the first phase retardation plate RF1, and the second phase retardation plate RF2 used has a positive retardation, and (2) the liquid crystal in the liquid crystal layer LQ The guiding system of the molecules 40 is set to be substantially parallel to the slow axis D1 of the first phase retardation plate RF1, and (3) the slow axis D1 of the first phase retardation plate RF1 is set to be the slow axis D2 of the second phase retardation plate RF2. It is about 90°. Correspondingly, the total delay of the front retardation R(RF1) of the first phase retardation plate RF1 of the first optical element OD1 and the front retardation R(RF2) of the second phase retardation plate RF2 and the residual delay R(LQ) of the liquid crystal layer LQ R(total) is expressed by R(total) = R(LQ) + R(RFl) - R(RF2). In this equation, the individual delays are set such that R(total) becomes zero, ie R(LQ) + R(RF1) = R(RF2). Therefore, optical compensation between the first optical element OD1 and the liquid crystal layer LQ can be achieved. Specifically, in the present embodiment, the backlight polarization state is not converted to a substantially linear polarization state by the first optical element OD1 itself. Considering the residual retardation of the liquid crystal layer LQ, the polarization state of the light emitted from the liquid crystal display panel LPN is converted into substantially linear polarization (ellipticity &lt; 0.1). More specifically, the residual retardation of the liquid crystal layer LQ and the first phase retardation plate The sum of the frontal delays of RF1 is set to be substantially equal to the positive delay of the second phase retarder RF2. Therefore, in the black display, after the backlight has passed through the first optical element OD1 and the liquid crystal layer LQ, the backlight from the backlight unit BL can be converted into light in a polarized state as close as possible to the linearly polarized light. Therefore, even in the case of the black display and the above-described white color development, the polarization state of the light emitted from the first optical element OD1 and the liquid crystal layer LQ can be made to be close to the linear polarization in which the ellipticity is substantially zero, so that it can be simply Second optical component OD2 127101-1001125.doc 16

1361932 • I Apply the second polarizer 52 to achieve good optical characteristics. Next, the arrangement of the first optical element 〇m and the second optical element OD2 on the liquid crystal display panel LPN will be described. Description will be made with reference to Fig. 4B in which the liquid crystal display device is viewed from the side of the counter substrate ct. For convenience, the x-axis and the γ-axis perpendicular to each other are defined in a plane parallel to the main surface of the array substrate AR (or the counter substrate CT), and the normal direction of the plate is defined as 2 axes. The phrase &quot;in-plane&quot; means &quot; in the plane defined by the axis and the axis. For example, the x-axis corresponds to the horizontal direction of the screen and the x-axis corresponds to the normal direction of the screen. Assume that the positive (+) side of the χ axis (0 direction) corresponds to the right side of the screen, and the negative (_) side of the χ axis (18 〇. square) corresponds to the left side of the screen. In addition, it is assumed that the positive (+) side of the γ-axis (9 〇. azimuth) corresponds to the upper side of the screen, and the negative (one) side of the γ axis (270. azimuth) corresponds to the lower side of the screen. In the liquid crystal display panel LPN, the rubbing direction of the alignment film 2 on the array substrate AR side is set to be 45 with respect to the X-axis. . The arrangement of the first optical element OD1 on the liquid crystal display panel LpN is set in accordance with the rubbing direction of the alignment film 20. Specifically, the first phase retardation plate is placed such that its slow axis D1 is guided to a direction parallel to the rubbing direction of the alignment film 2 。 45 to 225. Azimuth. At this time, included in the first phase retardation ruler The mixing direction of the liquid crystal molecules in the ^ is 225° in the direction opposite to the rubbing direction of the alignment film 2〇. The slow axis 〇2 of the second phase retardation plate RF2 is placed substantially perpendicular to the first phase retardation plate. The slow axis D1 of RF1 (ie, 135. azimuth, in addition, the first polarizer 51 is placed such that its absorption axis gossip and the first phase retardation plate) slow axis D1 and the second phase retarder RF2 slow axis D2 Approximately 45. For example, 9〇. to 127l01-1001125.doc 17 1361932 270° azimuth. On the other hand, the liquid crystal display panel Lpn is set according to, for example, the azimuthal direction of the substantially linear polarization from the liquid crystal layer LQ when displayed in black. Arrangement of the second optical element OD2 (in this case, the azimuth direction is parallel to the X axis. In the second optical element OD2, the second polarizing plate 52 is placed such that its absorption axis A2 is substantially parallel to the first Optical element 〇; 〇1 and liquid crystal layer LQ light polarization state (substantial line The long axis direction of the ellipsoid of the polarized light. In short, the second polarizing plate 52 can be placed such that its absorption axis A2 is located at 〇. to 18 〇. Azimuth. Figure 5 shows when a black display voltage is applied to the liquid crystal layer LQ ( For example, 4.8 v) is a polarization state of a backlight emitted from the first optical element 〇D 1 and the liquid crystal layer LQ having the above structure. In the black display state, the polarization state of light from the first optical element OD1 and the liquid crystal layer LQ It has the smallest possible amplitude (Es) with respect to the amplitude (Ep) in the long axis direction. The ellipticity of the polarized light is about 〇〇 17. In addition, it should be understood that the long axis direction of the substantially linear polarization is about 〇. Azimuth (X axis) Therefore, it should be understood that in order to display a high-quality black image, the absorption axis A2 of the second polarizing plate 52 is preferably set to 〇. Azimuth. (Example) Next, an example of a liquid crystal display device according to the present embodiment will be described. For example, the liquid crystal display device is designed in the following manner. In the liquid crystal display panel LPN, the liquid crystal layer LQ is composed of a liquid crystal composite including horizontally aligned liquid crystal molecules. MJ041113 (manufactured by Merck, Δη=0·065) It is applied as a liquid crystal composite. At this time, the direction of the liquid crystal molecules 4 限制 is restricted by the rubbing direction of the alignment film 20 on the side of the array substrate ar (liquid 12710M001125.doc • 18- 曰曰 molecules long pumping direction), and is set To be 45 with the X axis. The gap in the liquid crystal layer lq is not set to 4.9 pm. To achieve the black display, the voltage to be applied to the liquid crystal layer LQ is set at 4 8 (ν), at this time, the residual of the liquid crystal layer lQ The retardation is 60 (nm) 〇 firstly to compensate for the birefringence caused by the liquid crystal molecules 4 ,, the slow axis of the first phase retardation plate RF1 of the first optical element 〇〇1 placed on the outer surface of the array substrate AR D1 (ie, the alignment direction of the liquid crystal molecules 61 of the first phase retardation plate RF1) is set in an azimuth direction (for example, 225) substantially opposite to the rubbing direction of the array substrate Ar. Azimuth) to establish a compensation relationship. For example, setting the front retardation of the first phase retardation plate RF1 to i 〇〇 nm ° and then 'setting the slow axis D2 of the second phase retardation plate RF2 to the azimuthal direction (eg, 135. azimuth), which is substantially perpendicular to the liquid crystal molecules 4〇 and the slow axis D1 of the first phase delay plate RF1. The front retardation of the second phase retardation plate rF2 is set to, for example, 160 nm, which corresponds to the sum of the residual retardation of the liquid crystal layer LQ and the front retardation of the first phase retardation plate RF1. Then, the absorption axis A1 of the first polarizing plate 51 is set in an azimuth direction (for example, a 90° orientation), which is approximately the slow axis D1 of the first phase retardation plate rf1 and the slow axis D2 of the second phase retardation plate RF2. Into 45 ° intersection again. On the other hand, the absorption axis A2 of the second polarizing plate 52 of the second optical element OD2 placed on the outer surface of the counter substrate CT is set in an azimuthal direction (for example, 0. azimuth) which is substantially perpendicular to the first The absorption axis A1 of the polarizing plate 51. The azimuth direction of the slow axis of the phase retardation plate and the azimuth direction of the absorption axis of the polarizing plate are defined by the angle with the X axis as shown in Fig. 4B. The residual delay R (LQ) of the liquid crystal layer LQ, the delay of the first phase retardation plate RF1, 127101-1001125.doc • 19-1361932 R (RF1), and the delay R (RF2) of the second phase retardation plate RF2 are not limited to the above values. . If the delay value satisfies the relationship of R(LQ) + R(RF1) = R(RF2), the same result is obtained in all cases. An NH film (manufactured by Nippon Oil Corporation) having an average tilt angle β of 37° was applied as the first phase retardation plate (RF1). In this case, the average tilt angle β is defined as the angle between the main refractive index nz and the normal direction in the depth direction. In a simplified manner, the average tilt angle β is defined as the value given by [(higher tilt angle + lower tilt angle) / 2 + lower tilt angle]. For example, as shown in FIG. 4A, the "higher tilt angle" corresponds to the tilt angle of the liquid crystal molecules 61 (ie, the tilt to the main surface of the array substrate), which is included in the liquid crystal molecules of the mixed alignment and rises at the maximum angle. Up to the main surface of the array substrate AR. &quot;Lower tilt angle&quot; corresponds to the tilt angle of the liquid crystal molecules 61B, which is included in the liquid crystal molecules of the mixed alignment and raised to the main surface of the array substrate AR at a minimum angle. ZEONOR (manufactured by OPTES) is applied to Two-phase retardation plate RF2. According to the present example, as shown in Fig. 6, the measurement results of the dependence of the viewing angle and the contrast ratio are obtained. In the diagram showing the measurement results of the dependence on the viewing angle and the contrast ratio, the center corresponds to the liquid crystal. The normal direction of the display panel LPn, the concentric circle with respect to the normal direction corresponds to a tilt angle (viewing angle) of 1 〇 to 8 〇. The graph is obtained by connecting equal contrast regions in individual azimuth directions. 6Characteristics diagram. As shown in Fig. ,, according to this example, it is confirmed that a sufficient wide viewing angle with respect to the equal-ratio (CR)=10:1 of 160 is obtained in the upper and lower directions of the screen and in the left-right direction. The contrast ratio is 4〇〇. 127101-100I125.doc -20- 1361932 On the other hand, FIG. 7A shows the structure of Comparative Example 1. The structure of the liquid crystal display panel LPN is the same as in the example. However, in Comparative Example 1, The optical element OD1 includes a first polarizing plate, a 1/2 wavelength plate, and an NH film having an average tilt angle β 28 , and the second optical element 〇 D2 includes a second polarizing plate, a 1/2 wavelength plate, and a 1/4 wavelength plate. Fig. 7 shows the measurement result of the contrast ratio of the viewing angle disc in Comparative Example 1 which does not have the structure of Fig. 7. The angle of view of the equal contrast ratio (CR) = 1 〇: 1 is in the upper and lower directions of the screen and the left and right direction. The upper contrast is 14〇/145. The contrast in the normal direction of the glory is 250. The measurement result of the comparative example 1 is inferior to the measurement result of the example. According to the example of the present invention, the contrast in the normal direction of the screen and the like The range of viewing angles of the contrast ratios was confirmed. For these measurements, the contrast of the normal direction of the screen was measured by BM5_A (manufactured by TOPCON), and the viewing angle characteristics were measured by Ez-Contrast (manufactured by ELDIM). This specific embodiment is described with respect to the difference between the comparative example 2 having the structure shown in Fig. 8 (which is based on the same concept as the specific embodiment) and why a good viewing angle feature is obtained in the specific embodiment. The difference between the specific embodiment and the comparative example 2 shown in FIG. 8 is that the second phase retardation plate RF2 included in the first optical component 〇m of the present embodiment is included in the second optical component in Comparative Example 2 The present embodiment and the comparative example 2 are the same in the following aspects: the liquid crystal layer Lq; the axial relationship between the first polarizing plate 51 and the first phase retardation plate RF1 in the first optical element OD1; the first phase retardation plate The relationship between the axial angle of the ruler and the liquid 127101-1001 J25.doc • 21· 1361932 B 曰 molecules included in the liquid crystal layer LQ; the front retardation R (RF1) of the first phase retardation plate RF1; And an average tilt angle of the first phase retardation plate RF1. In addition, the present embodiment and the comparative example 2 are the same in the following aspects. The absorption axis A2 of the second polarizing plate 52 included in the second optical element 〇D2 is disposed at an angle with respect to the liquid crystal display panel LPN; and includes the second optical 兀The second phase retarder in the piece! The frontal delay R (RF2) of ^2; and the axial relationship between the slow axis D2 of the second phase retardation plate RF2 and the slow axis D1 of the first phase retardation plate RF1. Therefore, it is apparent that the T-V characteristic in the front side direction (i.e., the normal direction of the screen) (i.e., the relationship between the transmittance and the voltage applied to the liquid crystal layer LQi) is the same as in the comparative example 2 shown in Fig. 2 in the present embodiment. Fig. 9A shows simulation results of the viewing angle characteristics of the present embodiment, and Fig. 9B shows simulation results of the viewing angle characteristics of Comparative Example 2. From the simulation results, it should be understood that the specific embodiment and Comparative Example 2 have substantially the same features in the front side direction, but are completely different in the viewing angle characteristics, and the specific embodiment has good viewing angle characteristics, but Comparative Example 2 has a narrower Perspective. To explain the result, with respect to each structure, an analysis is performed on the matching between the polarization state of the backlight from the first optical element and the liquid crystal layer LQ and the polarization state of the ambient light having passed through the second optical element 〇d2. It is now assumed that a predetermined voltage (= 4.8 V) for black display is applied to the liquid crystal layer LQ. Fig. 10A is a characteristic diagram showing the matching between the two polarization states in the up and down direction of the screen in the embodiment, and Fig. 10B is a characteristic diagram showing the matching between the two polarization states in the up and down direction of the screen in Comparative Example 2. The abscissa indicates an angle with the normal line in the up and down direction of the screen, and the ordinate indicates the ellipticity at a wavelength of 55 〇 nm as a parameter indicating the state of polarization. The figure symbol 127101-1001125.doc • 22· 1361932 A corresponds to the polarization state of the backlight from the first optical element 0D1 and the liquid crystal layer Lq, and the symbol &quot;B corresponds to the second optical element 〇D2 The polarization state of the ambient light. The orientation direction of the liquid crystal molecules in the liquid crystal layer LQ is set at 45. Therefore, the viewing angles in the vertical direction of the screen show the same viewing angle characteristics in the left and right direction of the screen in the vertical direction of Fig. 10A and Fig. 10B. The viewing angle compensation is important from the first optical element 〇D1 and the liquid crystal layer [(the polarized state of the backlight substantially coincides with the polarized state of the ambient light that has passed through the second optical element 〇D2. As is clear from FIG. 10A, The two polarization states are substantially identical in this embodiment. However, as shown in FIG. 0B, in Comparative Example 2, the two polarization states become significantly different as the viewing angle increases. In addition, it should be understood that the front side of Comparative Example 2 is The polarization state is an elliptical polarization of ellipticity &gt; ,7, and in the present embodiment, the front side polarization state is close to the ellipticity &lt; 〇.丨 substantial linear polarization. The difference between the example and the comparative example 2 is that linear polarization (or elliptical polarization with a small ellipticity) is mainly used in the present embodiment, and circular polarization (or elliptical polarization with a large ellipticity) is mainly used for In Comparative Example 2, in the case of applying an elliptical polarization with a large ellipticity in the normal direction of the screen, 'as in Comparative Example 2', a good display quality cannot be obtained normally unless it is additionally provided in the second optical element 〇D2. A third phase retardation plate RF3 (negative α plate; nC) having a relationship of nx==ny&gt;nz between the main refractive indices nx, ny, and nz or a negative biaxial film having a nx&gt;ny&lt;nu| system As the second phase retardation plate RF2. 127101-100H25.doc -23- 1361932 FIG. 11A shows that a negative C plate (manufactured by Nitto Denko) is placed in the structure of Comparative Example 2 as the second optical element 〇D2 and the liquid crystal layer. The viewing angle characteristic in the case of the third phase retardation plate between lq. In the negative C plate, the retardation (Rth) defined by &quot;Rth=[(nx-ny)/2_nz]x film thickness&quot; is set at 80 nm. Figure 11B shows the placement of a negative c-plate (Rth = 80 nm) on the second optical element OD2 and liquid In the structure between the layers lq, the polarization state of the backlight from the first optical element 〇〇1 and the liquid crystal layer LQ matches the polarization state of the ambient light that has passed through the second optical element 〇d2. The matching is good, and good viewing angle characteristics can also be obtained. On the other hand, in the specific embodiment, the polarization state of the backlight from the first optical element OD1 and the liquid crystal layer LQ can be converted to a near ellipticity in the front side of the screen. An elliptical polarization state of substantially linear polarization of 0.1. Therefore, the viewing angle compensation can be completed by the second polarizing plate 52 itself, even if the negative C plate (n-C) or the negative biaxial film (NB) is not applied to the second optical element OD2. Therefore, it is possible to provide a liquid crystal display device having good display quality, which can achieve thickness reduction and cost reduction. The invention is not limited to the specific embodiments described above. In practice, structural elements may be modified without departing from the spirit of the invention. Various inventions can be implemented by appropriately combining the structural elements disclosed in the specific embodiments. For example, some structural elements may be omitted from all structural elements disclosed in the specific embodiments. Further, structural elements in different specific embodiments may be combined as appropriate. ▲ For example, in the above specific embodiment, each of the heart channel thin film transistors of the switching element w is composed. However, other structures may be employed if a variety of similar types of drive signals are produced. 127l01-100H25.doc -24 - 1361932 The second optical element 〇D2 may include a third phase retardation plate corresponding to the negative C plate between the second polarizing plate 52 and the liquid crystal display panel LPN. Specifically, as shown in FIG. 12A, in the liquid crystal display device according to the modification of the present invention, the second optical element OD2 is composed of the second polarizing plate 52 and the third phase retardation plate RF3, and is placed in the second polarized light. Between the board 52 and the liquid crystal display panel LPN. The third phase retardation plate RF3 has a refractive index anisotropy, which is defined by the relationship nx=ny>nz, where nx and ny are refractive indices perpendicular to each other in a plane of the third phase retardation plate. (10) is a refractive index in the normal direction of the third phase retardation plate RF3. In the third phase retardation plate RF3, the retardation Rth in the normal direction is set at 8 〇 nm. According to the modification regarding this structure, as shown in FIG. 2B, the measurement results of the viewing angle and the contrast ratio in the structure of the specific embodiment (shown in FIG. 3) in which the third phase retardation plate RF3 is not provided should be understood (FIG. 6). In comparison, an approximately equal viewing angle is obtained in an area having a lower contrast ratio (for example, CR = 1 〇: 1). However, it should be understood that a wider viewing angle is obtained in a region having a more contrast ratio (e.g., CR = 50: 1) in the structure of the specific embodiment in which the third phase retardation plate RF3 is not provided. It is not obvious that even in the case where the negative biaxial film (nb) is applied as the third phase retardation plate RF3, similar features can be obtained as shown in Fig. i2B. According to the above results, specifically to increase the area of the higher contrast ratio, it is determined that the structure of the specific embodiment (ie, the second optical element does not include the negative (3) and the structure of the negative biaxial film t) includes the negative (3) or The structure of the third phase retardation plate composed of a negative biaxial film is more advantageous. In the above specific embodiment, preferably, the first phase retardation plate (RF1) is composed only of the liquid crystal film layer 60. Specifically, in the specific embodiment, the first phase delay is 12710I-100lJ25.doc -25-1361932. The plate RF1 is composed of a liquid crystal film layer 60 which contacts the second phase retardation plate RF2 and the outer surface of the liquid crystal display panel LPN (ie, The outer surface of the insulating substrate 10 constituting the array substrate AR) has a phase retardation plate including a liquid crystal film layer of mixed alignment liquid crystal molecules, for example, an NH film, which is obtained by performing alignment processing on a base film, The liquid crystal material is coated on the base film, and the liquid crystal material is cured to a state in which the liquid crystal molecules maintain a predetermined alignment state. Triacetate (TAC) is widely used as a basement membrane. However, the base film itself has a delay. To achieve good optical compensation, compensation needs to be performed by considering the base film delay. Therefore, optical compensation can be easily realized by applying the NH film without a base film to the above-described book example. For reference purposes, Fig. 13 shows the measurement result 'obtained by measuring the viewing angle and the contrast ratio in the case where the NH film having the base film is applied as the first phase retardation plate RF1 having the same structure as the example. It should be understood that an angle of view which is approximately equal to the angle of view of the baseless film structure in the example shown in Fig. 6 is obtained in a region having a lower contrast ratio (e.g., CR = 1 〇: 1). However, it should be understood that in the example base-free film structure, a wider viewing angle is obtained in a region having a higher contrast ratio (e.g., CR = 50: 1). According to the above-mentioned results, in particular, in order to increase the region of high contrast ratio, the structure of the example (i.e., the structure of the first phase retardation plate RF1 using no base film (without TAC)) has a base film (TAC) than the application. The structure of the first phase retardation plate (RF1) is more advantageous. In the above specific embodiment, the first phase retardation plate RF1 having the liquid crystal film layer 6 is preferably used, which has a large average inclination angle β, for example, β = 37. Or approximate this value. For reference purposes, Figure 14 shows the measurement results for the system with 12710M00U25.doc

S -26 - 1361932 • . The same structure is applied with β=28. In the case of the first retardation film (ruthenium film) of the liquid crystal film, it is obtained by measuring the viewing angle and the contrast ratio. It should be understood that (4) is obtained in an area having a lower contrast ratio (e.g., CR = i 〇: i) which is approximately equal to the example shown in Fig. 6. The perspective of the structure - the perspective. ^ However, it should be understood that β = 37 in this example. In the structure, a wider viewing angle is obtained in a region having a higher contrast ratio (e.g., CR = 50: 1). According to the above results, in particular, in order to increase the area of the high contrast ratio, the structure of the example (i.e., the structure of applying the first phase retardation plate RF1 having the liquid crystal film having a large average inclination angle) is more than the application having the average inclination angle. The structure of the first phase retardation plate RF1 of the small liquid crystal film is more advantageous. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in FIG. 1 is a view schematically showing the structure of a liquid crystal display device according to an embodiment of the present invention; FIG. 2 is a view schematically showing a sectional structure of the liquid crystal display device shown in FIG.; FIG. 3 is a view schematically showing that it can be applied to FIG. The structure of the first optical element and the second optical element of the liquid crystal display device shown in FIG. 4A is used to illustrate the alignment between the liquid crystal molecules of the liquid crystal display panel and the alignment of the liquid crystal molecules of the first phase retardation plate when a voltage is applied. Figure 4B is a diagram for explaining the slow axis azimuth direction of the phase retardation plate shown in Figure 3 and the absorption axis azimuth direction of the polarizing plate; 127101-100H25.doc • 27- Figure 5 shows the basis DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A characteristic view of a polarized state after a backlight has passed through a first optical element and a liquid crystal layer in a liquid crystal display device; FIG. 6 is a view showing a dependency of a viewing angle and a contrast ratio in a liquid crystal display device according to an example of the present embodiment. FIG. 7A is a view schematically showing the structure of a liquid crystal display device according to Comparative Example 1; FIG. 7B is a view showing a viewing angle of the liquid crystal display device according to Comparative Example 1. A characteristic diagram of the measurement result of the dependency of the ratio; FIG. 8 schematically shows the structure of the liquid crystal display device according to Comparative Example 2; FIG. 9A shows the viewing angle and the pair of the liquid crystal display device according to the example of the present embodiment. FIG. 9B is a characteristic diagram showing simulation results of the dependence of the viewing angle and the contrast ratio in the liquid crystal display device according to Comparative Example 2; FIG. 10A shows an example of the present embodiment. a characteristic map in which the ellipticity in the vertical direction of the polarization state of the backlight of the first photonic element and the liquid crystal layer is matched with the change in the ellipsoidal-round rate change in the up-and-down direction of the polarization state of the ambient light that has passed through the second optical element; 10B shows that in the comparative example 2, the ellipticity change in the up-and-down direction of the polarization state of the backlight that has passed through the first optical element and the liquid crystal layer matches the ellipticity change in the up-and-down direction of the polarization state of the ambient light that has passed through the second optical element. FIG. 11A shows a case where a negative c-plate is placed between the second optical element and the liquid crystal layer, in Comparative Example 2 Measurement of the dependence of the angle of view and the contrast ratio 127101-1001125.doc

FIG. 11B shows a situation in which a negative c-plate is placed between the second optical element and the liquid crystal layer, and the first optical element and the liquid crystal layer have passed through the comparative example 2. a characteristic map in which the ellipticity change in the up-and-down direction of the polarized state of the backlight is matched with the ellipticity change in the up-and-down direction of the polarized state of the ambient light passing through the first optical element;

12A is a view schematically showing the structure of a liquid crystal display device according to a modification of the present embodiment, wherein a second optical element is disposed which is configured to place a third phase retardation plate (negative C plate) on the second polarizing plate. FIG. 12B is a characteristic diagram showing measurement results of the dependence of the viewing angle and the contrast ratio in the modification shown in FIG. 12; FIG. 13 is a view showing the dependence of the viewing angle and the contrast ratio in the specific embodiment. A characteristic diagram of the measurement results 'the NH film including the base film is used as the first phase retardation plate; and FIG. 14 is a characteristic diagram of the measurement result of the angle of view and the dependence on 0 in the present embodiment. The film having the average tilt angle is used as the first phase retardation plate. [Main component symbol description] 10 Insulating substrate 12 Semiconductor layer 12C Channel region 12D &gt; and Polar region 12S Source region 14 Gate insulating film 127101-1001125.doc • 29· 1361932 16 Interlayer insulating film 18 Organic insulating film 20 Alignment film 30 Light transmissive insulating substrate 34 Color filter layer 36 Alignment film 40 Liquid crystal molecules 51 First polarizing plate 52 Second polarizing plate 60 Liquid crystal film layer 61A Liquid crystal molecules 61B Liquid crystal molecules A1 Absorption axis AR Array substrate CNT Controller CT Anti-substrate D2 Slow axis DSP display area EP pixel electrode ET Counter electrode LPN Liquid crystal display panel LQ Liquid crystal layer OD1 First optical element OD2 Second optical element 12710M001125.doc -30 1361932 » »

PX pixel RF1 first phase delay plate RF2 second phase delay plate RF3 third phase delay plate W switching element WG gate electrode X signal line XD signal line driver Y scan line YD scan line driver 127101-1001125.doc -31 -

Claims (1)

X. Patent application scope: 1 - A liquid crystal display device comprising: a liquid crystal display panel, wherein a liquid crystal layer including horizontal alignment liquid crystal molecules is held in a first substrate and a second substrate disposed opposite to each other a first optical component is disposed on one of the outer surfaces of the liquid crystal display panel, and includes a first polarizing plate, and is disposed between the first polarizing plate and the liquid crystal display panel a phase retarder and a second phase retarder; and a second optical component comprising: a second polarizer disposed on the other outer surface of the liquid crystal display panel, wherein the first phase retarder comprises a liquid crystal a film layer that imparts a predetermined phase delay to light of a predetermined wavelength, and wherein the nematic liquid crystal molecules are immobilized into a state in which the isotropic liquid crystal molecules are mixed and aligned in a normal direction; wherein In the optical component, an angle between an absorption axis of one of the first polarizers and one of the slow axes of the second phase retardation plate is set at about 45°, and one of the slow axes of the first phase retardation plate is included in the liquid One of the directors of the liquid crystal molecules in the crystal layer is set to be substantially parallel, and an angle between the slow axis of the first phase retardation plate and the slow axis of the second phase retardation plate is set. It is about 90. And in the second optical element, an angle between an absorption axis of the second polarizing plate and the absorption axis of the first polarizing plate is set to be about 90. . 2. The liquid crystal display device of claim 1, wherein the first optical element controls 127101-1001125.doc 1361932 by a polarized state of light of the first optical element such that light having a substantially linearly polarized polarization state enters the liquid crystal Floor. 3. The liquid crystal display device of claim 1, wherein the first phase retardation plate is composed of the liquid crystal film layer contacting the second phase retardation plate and the outer surface of the liquid crystal display panel. 4. The liquid worm display device of claim 1, wherein a residual delay of one of the liquid crystal layers and a frontal retardation of the first phase retardation plate is substantially equal to one of the second phase retardation plates Positive delay. 5. The liquid crystal display device of claim 1, wherein the second optical element comprises a third phase retardation plate between the first polarizing plate and the liquid crystal display panel, and the third phase retardation plate has a refractive index Anisotropy, which is defined by a relationship of nx=ny> nz, wherein (10) and lanthanum are refractive indices in a direction perpendicular to each other in a plane of the third phase retardation plate, and nz is the third phase retardation plate The refractive index in a normal direction. 6. The liquid crystal display device of claim 1, further comprising a backlight unit that illuminates the liquid crystal display panel from the first optical element side. 127l01-1001125.doc