Retardation plate, liquid crystal projector, and contrast adjustment method

Abstract

A phase difference sheet including a substrate and a phase difference film as a tilt film, wherein, in a biaxial refractive index ellipsoid exhibiting a refractive index anisotropy, of three principal refractive indexes nx, ny, nz, the principal refractive index in the length direction of a columnar structure, i.e., the X-axis direction, is nx, the principal refractive index in the major axis direction of an ellipse perpendicular to the X-axis, i.e., the Y-axis direction, is ny, and the principal refractive index in the minor axis direction, i.e., the Z-axis direction, is nz, the following conditional expression (1) is satisfied, and, in a case where the incident angle of a direction tilted to the X-axis side with the normal as a reference is positive, the phase difference of incident light at an incident angle of +30° is Re(+30), the phase difference of incident light at an incident angle of -30° is Re(-30), and the ratio of Re(+30) to Re(-30), i.e., the phase difference ratio, is Re(30) ratio, the following conditional expression (2) is satisfied, ny > nx > nz (1), Re(30) ratio = Re(30) / Re(-30) = 1.1 to 4.0 (2).

Description

Technical Field

[0001] This invention relates to a phase difference filter, a liquid crystal projector, and a contrast adjustment method. Background Technology

[0002] A phase difference plate serves as a phase difference compensation plate, for example, in a liquid crystal display device using VA (Vertical Alignment) mode (see Japanese Patent No. 4744606). In a VA mode liquid crystal display device, the polarizer and analyzer holding the liquid crystal layer are orthogonally arranged with their respective transmission axes orthogonal, and the orientation of the liquid crystal layer is perpendicular to the substrate surface in a low-voltage state. Therefore, in a low-voltage state, linearly polarized light passing through the polarizer passes through the liquid crystal layer while maintaining the orientation of its polarization axis and is incident on the analyzer. Since the polarization axis of the linearly polarized light incident on the analyzer is orthogonal to the transmission axis of the analyzer, theoretically no light passes through the analyzer, resulting in a black display. However, because the liquid crystal layer has refractive index anisotropy (also known as birefringence), which generates a refractive index difference between polarized light with different polarization axes due to the tilted orientation component, a phase difference is generated between the light passing through the liquid crystal layer and the polarized light with different polarization axes. If there is a phase difference between polarized light, the light incident on the analyzer becomes elliptically polarized, so even at low voltage, some light still passes through the analyzer. This results in reduced contrast in black displays. A phase difference compensation plate compensates for the phase difference generated within the liquid crystal layer. That is, the phase difference compensation plate reduces the light transmitted through the analyzer by generating a phase difference that cancels out the phase difference caused by the liquid crystal layer. This improves the contrast of black displays.

[0003] As described in Japanese Patent No. 4744606, as an example, the phase difference compensation plate is constructed as a stack of multiple plates with different optical anisotropies. Japanese Patent No. 4744606 describes a C-plate and an O-plate as the multiple plates. The C-plate is formed by stacking layers with different refractive indices along the normal direction of the plate. The optical axis of the C-plate, which does not exhibit refractive index anisotropy, is aligned with the normal of the plate, and generates a phase difference for light incident from a direction different from the normal.

[0004] Japanese Patent Application Publication No. 10-81955 discloses a problem with tilted evaporation films used as retarders: relaxation of the columnar structures formed by the presence of multiple columnar structures causes light scattering within the tilted evaporation film, resulting in cloudiness and deterioration of the film's quality as a retarder. The relaxation of the columnar structures refers to the phenomenon of aggregation of multiple columnar structures. Furthermore, Japanese Patent Application Publication No. 10-81955 discloses a retarder that suppresses light scattering within the film by alternately stacking tilted and front-side evaporation films.

[0005] Japanese Patent Application Publication No. 2013-113869 discloses that in the refractive index ellipsoid displaying the characteristics of the O-plate, the axis representing the maximum principal refractive index is approximately aligned with the length direction of the columnar structure, i.e., the growth direction. Furthermore, it discloses that in this O-plate, the ratio Re(30) / Re(-30) of the phase difference Re(30) in a direction inclined 30° from the normal direction toward the growth direction of the columnar structure to the phase difference Re(-30) in a direction inclined 30° from the normal direction toward the opposite side of the growth direction is preferably 3.5 or more and 4.5 or less.

[0006] Japanese Patent Application Publication No. 2009-145861, similar to Japanese Patent Application Publication No. 2013-113869, discloses an O-plate in which the axis representing the maximum principal refractive index is approximately aligned with the length direction of the columnar structure. Furthermore, Japanese Patent Application Publication No. 2009-145861 discloses that by setting the phase difference ratio Re(-30) and the front phase difference Re(0) of the O-plate to appropriate values, high-contrast display can be achieved in a liquid crystal display device. Summary of the Invention

[0007] The technical problem to be solved by the invention

[0008] One embodiment of the present invention aims to provide a phase difference sheet, a liquid crystal projector, and a contrast adjustment method that can improve contrast by compensating for the phase difference caused by the liquid crystal layer.

[0009] means for solving technical problems

[0010] The retardation film of the present invention comprises a substrate and a retardation film formed on at least one side of the substrate. The retardation film is an inclined film having a columnar structure inclined relative to the normal of the film-forming surface on which the retardation film is formed, and exhibits refractive index anisotropy as an optical property.

[0011] In a biaxial refractive index ellipsoid that displays refractive index anisotropy, the three principal refractive indices are set as nx, ny, and nz. Specifically, the principal refractive index along the length direction of the columnar structure (i.e., the X-axis) is set as nx, the principal refractive index along the major axis direction of the ellipse perpendicular to the X-axis (i.e., the Y-axis) is set as ny, and the principal refractive index along the minor axis direction (i.e., the Z-axis) is set as nz. The following condition (1) is satisfied.

[0012] Furthermore, when the incident angle tilted towards the X-axis with reference to the normal is set to positive, the phase difference of the incident light at an incident angle of +30° is set to Re(+30), the phase difference of the incident light at an incident angle of -30° is set to Re(-30), and the ratio of Re(+30) to Re(-30), i.e. the phase difference ratio, is set to the Re(30) ratio, the following condition (2) is satisfied.

[0013] ny>nx>nz (1)

[0014] Re(30) ratio=Re(30) / Re(-30)=1.1~4.0 (2)

[0015] In the phase difference plate of the present invention, it is preferable that the slow axis is defined as the YS axis, which corresponds to the principal refractive index ny among the three principal refractive indices and is projected onto a plane parallel to the film forming surface, and which corresponds to the principal refractive index ny and has the longest phase delay of the incident light, and the ZS axis is defined as the axis on which the X axis is projected onto the film forming surface. In this case, the slow axis is orthogonal to the ZS axis.

[0016] In the phase difference plate of the present invention, it is preferred that the Re(30) ratio satisfies the following condition (2-1).

[0017] Re(30) ratio=Re(30) / Re(-30)=1.2~4.0 (2-1)

[0018] In the phase difference plate of the present invention, it is preferred that the Re(30) ratio satisfies the following condition (2-2).

[0019] Re(30) ratio=Re(30) / Re(-30)=1.4~3.0 (2-2)

[0020] In the phase difference plate of the present invention, it is preferred that the Re(30) ratio satisfies the following condition (2-3).

[0021] Re(30) ratio=Re(30) / Re(-30)=1.5~2.5 (2-3)

[0022] In the phase retardation film of the present invention, the tilting film is preferably formed from an oxide containing at least one of Si (silicon), Nb (niobium), Zr (zirconium), Ti (titanium), La (lanthanum), Al (aluminum), Hf (hafnium) and Ta (tantalum).

[0023] In the phase retardation film of the present invention, two or more phase retardation films may be stacked.

[0024] In the retardation plate of the present invention, it is preferable to set the YS axis, which corresponds to the principal refractive index ny among the three principal refractive indices and is the one with the longest phase delay of the incident light corresponding to the principal refractive index ny, onto a plane parallel to the film formation surface, as the slow axis, and to set the orientation of the slow axis when the substrate is rotated about the normal as the azimuth angle of the substrate.

[0025] Within an azimuth angle of 0° to 360°, the azimuth angle with the largest phase difference for incident light at an angle of incidence of +15° relative to the normal is set as the reference azimuth angle. The absolute value of the difference between the first phase difference of the incident light at an azimuth angle of +45° relative to the reference azimuth angle and the second phase difference of the incident light at an azimuth angle of -45° relative to the reference azimuth angle is less than 6 nm.

[0026] In the phase difference plate of the present invention, the front phase difference is preferably 0.1 nm to 5 nm.

[0027] In the phase difference plate of the present invention, the haze value, which indicates the degree of generation of scattered light, is preferably 0.3% or less.

[0028] In the phase retardation film of the present invention, when two or more phase retardation films are stacked, it is preferable to form a phase retardation film on each of the two sides of the substrate.

[0029] In the phase retardation film of the present invention, when two or more phase retardation films are stacked, two or more phase retardation films can be stacked on one side of the substrate, and an intermediate layer can be provided between adjacent phase retardation films.

[0030] In the phase retardation film of the present invention, when two or more phase retardation films are stacked, multiple substrates having at least one phase retardation film formed thereon can be provided.

[0031] In the phase retardation film of the present invention, two phase retardation films are preferably stacked, and their slow axes are configured with an intersection angle within ±3° of 90°.

[0032] In the phase retardation film of the present invention, it is preferable that two phase retardation films are stacked, and the difference between their front-side phase differences is less than ±3nm.

[0033] In the phase difference plate of the present invention, a negative C plate with a haze value of 0.4% or less, which indicates the degree of generation of scattered light, may also be included.

[0034] In the phase difference plate of the present invention, the C plate preferably has an anti-reflection function.

[0035] In the phase retardation plate of the present invention, it is preferable that, when a C-plate is provided, the haze value, which indicates the degree of generation of scattered light, is 1% or less.

[0036] The retardation film of the present invention comprises a substrate and a retardation film formed on at least one side of the substrate, wherein two or more retardation films are stacked.

[0037] In a plane of the substrate parallel to the film formation surface where the phase retardation film is formed, the axis with the longest phase delay of the incident light is defined as the slow axis, and the orientation of the slow axis when the substrate rotates around the normal is defined as the azimuth angle of the substrate.

[0038] Within an azimuth angle of 0° to 360°, the azimuth angle with the largest phase difference for incident light at an angle of incidence of +15° relative to the normal is set as the reference azimuth angle. The absolute value of the difference between the first phase difference of the incident light at an azimuth angle of +45° relative to the reference azimuth angle and the second phase difference of the incident light at an azimuth angle of -45° relative to the reference azimuth angle is less than 6 nm.

[0039] The liquid crystal projector of the present invention includes a liquid crystal layer and a phase difference compensation element for compensating for the phase difference generated in the liquid crystal layer. As the phase difference compensation element, it includes the phase difference sheet of the present invention.

[0040] The contrast adjustment method of the present invention is a contrast adjustment method for a liquid crystal display element, the liquid crystal display element comprising a liquid crystal layer and a phase difference compensation element for compensating for phase differences generated in the liquid crystal layer. In this contrast adjustment method...

[0041] As a phase difference compensation element, a phase difference sheet is used, which has multiple substrates having at least one phase difference film formed on them.

[0042] The contrast of a liquid crystal display element is adjusted by rotating at least one of a plurality of substrates having at least one retardation film formed on it about an axis perpendicular to the film formation surface relative to the other substrates. Attached Figure Description

[0043] Figure 1 This diagram illustrates the general structure of a liquid crystal display element and the function of the phase difference compensation element.

[0044] Figure 2 This is an illustration of the pre-tilt of liquid crystal molecules in a liquid crystal display element.

[0045] Figure 3 This is a cross-sectional view of the phase difference plate according to the first embodiment.

[0046] Figure 4 This is an illustrative diagram of the evaporation method for tilted films.

[0047] Figure 5 This is an illustration of the refractive index ellipsoid representing the optical properties of a tilted film.

[0048] Figure 6 yes Figure 5The three-view diagram of the refractive index ellipsoid is shown. Figure 6 A is the view along the Y-axis. Figure 6 B is the view along the Z-axis. Figure 6 C is the X-axis view.

[0049] Figure 7 This is an illustration of the slope of the refractive index ellipsoid relative to the phase difference plate. Figure 7 A is a diagram representing the overall image of the refractive index ellipsoid. Figure 7 B is a diagram showing a cross-section parallel to the film-forming surface of the refractive index ellipsoid.

[0050] Figure 8 This is a cross-sectional view of the refractive index ellipsoid as viewed from each axis of the phase difference plate.

[0051] Figure 9 This is a graph showing the relationship between the incident angle of light and the phase difference film when measuring the phase difference Re(θ).

[0052] Figure 10 This is a diagram illustrating the method for measuring haze.

[0053] Figure 11 This is a graph showing the relationship between Re(30) ratio and haze.

[0054] Figure 12 This is a graph showing the relationship between the substrate setting angle ω and the Re(30) ratio.

[0055] Figure 13 This is a graph representing the dependence of the phase difference of the tilted membrane on the incident angle.

[0056] Figure 14 It is a diagram used to illustrate the phase difference of light incident from the growth direction and from directions orthogonal to the growth direction. Figure 14 A is a diagram illustrating the direction of light incidence. Figure 14 B is a cross-sectional view of the refractive index ellipsoid perpendicular to LX. Figure 14 C is a cross-sectional view of the refractive index ellipsoid perpendicular to LZ.

[0057] Figure 15 This is an explanatory diagram of the evaluation method for uneven black display.

[0058] Figure 16 This is a perspective view showing the schematic structure of the phase difference plate in the second embodiment.

[0059] Figure 17 This is an illustration of the slow axis of synthesis when two tilted membranes are present. Figure 17 A is a schematic diagram showing the relationship between the slow axis of the tilted film and the fast axis of the liquid crystal layer. Figure 17 B is an illustrative diagram of the synthesis of the slow axis of the tilted membrane.

[0060] Figure 18 This is an illustration of the in-plane optical anisotropy of the substrate of the tilted film. Figure 18 A is a diagram representing the slow and fast axes of the tilted membrane. Figure 18 B is a cross-sectional view of the inclined membrane in the 0-180° orientation. Figure 18 C is a cross-sectional view of the inclined membrane at an angle of 90-270°.

[0061] Figure 19 This is a graph showing the azimuth dependence of the phase difference when the slow axis cross angle of the two tilted membranes is 90°.

[0062] Figure 20 This is a graph showing the azimuth dependence of the phase difference when the slow axis cross angle of the two tilted membranes deviates from 90°.

[0063] Figure 21 This is a diagram showing the relationship between the slow axis crossing angle of the two tilted films and the phase difference of the phase difference plate.

[0064] Figure 22 This is a graph showing the relationship between the frontal phase difference ΔRe(0) of the two tilted films and the peak orientation of the phase difference IRe(15) of the phase difference plate.

[0065] Figure 23 This is a graph showing the relationship between the frontal phase difference ΔRe(0) of the two tilted films and the peak value IRe(15)max of the phase difference IRe(15) of the phase difference plate.

[0066] Figure 24 This is a graph showing the relationship between the frontal phase difference ΔRe(0) of the two tilted films and Re(15)90-Re(15)0, i.e., ΔRe(15), in the phase difference plate.

[0067] Figure 25 This is a diagram showing a phase retardation plate with a tilted film on each side and an anti-reflective film.

[0068] Figure 26 This is a diagram showing a phase difference plate with two tilted films on one side.

[0069] Figure 27 This is a diagram showing a phase retardation plate with two tilted films on one side and an anti-reflective film on the other.

[0070] Figure 28 This is a diagram showing the relationship between the substrate setting angle of a phase retardation film with two tilted films and the haze.

[0071] Figure 29 This is a cross-sectional view showing the schematic structure of a phase difference plate with a planarization layer placed between two inclined films.

[0072] Figure 30 This is a diagram showing the relationship between the substrate setting angle and haze of a phase retardation film with a planarization layer set between two tilted films.

[0073] Figure 31 This is an explanatory diagram of a phase retardation plate with tilted films disposed on different substrates.

[0074] Figure 32 This is a diagram showing an example of the layer structure of a phase retardation plate with three tilted films.

[0075] Figure 33 This is an illustration of the slow axis of synthesis when a three-layer tilted membrane is used. Figure 33 A is a schematic diagram showing the relationship between the slow axis of the tilted film and the fast axis of the liquid crystal layer. Figure 33 B is an illustrative diagram of the synthesis of the slow axis of the tilted membrane.

[0076] Figure 34 This is an explanatory diagram of a phase difference plate with a C-plate.

[0077] Figure 35 This is an explanatory diagram for board C.

[0078] Figure 36 This is an illustration of the azimuth dependence of the phase difference on the C-plate.

[0079] Figure 37 This is an illustration of a C-plate formed only on one side of a substrate.

[0080] Figure 38 This is a graph showing the relationship between Re(30) and haze for two-sided and single-sided C-plates.

[0081] Figure 39 It is a 3D view showing the appearance of an LCD projector.

[0082] Figure 40 This is a block diagram representing the optical structure of a liquid crystal projector. Detailed Implementation

[0083] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0084] Liquid crystal display element

[0085] First, refer to Figure 1 The following describes a liquid crystal display element 10, which is equipped with the phase difference plate of the present invention as a phase difference compensation element 20. The liquid crystal display element 10 is, for example, provided in the liquid crystal projector 110 described later (see reference 110). Figure 39 and Figure 40 )middle.

[0086] The liquid crystal display element 10 is a transmissive VA mode liquid crystal display element. That is, liquid crystal molecules, which are oriented approximately perpendicularly to the element surface in the liquid crystal layer of the liquid crystal display element 10 in the absence of voltage, are encapsulated therein. The liquid crystal display element 10 adjusts the voltage applied to the liquid crystal layer for each pixel, thereby changing the orientation of the liquid crystal molecules. As a result, the polarization state of the light transmitted to each pixel is controlled, and an image is displayed.

[0087] like Figure 1 As shown in Figure A, the liquid crystal display element 10 includes a polarizer 15, a liquid crystal layer 17, and an analyzer 19 sequentially from the light source side, and a phase difference compensation element 20 is provided between the liquid crystal layer 17 and the analyzer 19.

[0088] The polarizer 15 is a polarizer that transmits only the polarization component of the incident light in the direction of the transmission axis T1 (indicated by the arrow) to the side of the liquid crystal layer 17. That is, the light incident on the liquid crystal layer 17 is only the incident light L0, which has an electric field vibrating in a direction parallel to the transmission axis T1.

[0089] The analyzer 19 is a polarizer that transmits only the polarization component of the light transmitted through the liquid crystal layer 17, whose phase difference is compensated by the phase difference compensation element 20, in the direction of the transmission axis T2 indicated by the arrow. The analyzer 19 is configured such that its transmission axis T2 is orthogonal to the transmission axis T1 of the polarizer 15. That is, the analyzer 19 and the polarizer 15 are configured in a so-called orthogonal Nicol configuration. Therefore, the liquid crystal panel using the liquid crystal display element 10 becomes a normally black transmissive liquid crystal panel that displays black in the absence of voltage.

[0090] The liquid crystal layer 17 is composed of transparent substrates 71 and 72 and rod-shaped liquid crystal molecules 75 encapsulated between these transparent substrates 71 and 72.

[0091] Furthermore, the transparent substrates 71 and 72 are, for example, composed of a glass substrate 77, a transparent electrode 78, and an alignment film 79. In the transparent substrate 71, the glass substrate 77, the transparent electrode 78, and the alignment film 79 are arranged sequentially from the light source side. Conversely, in the transparent substrate 72, the alignment film 79, the transparent electrode 78, and the glass substrate 77 are arranged sequentially from the light source side.

[0092] The transparent electrode 78 is connected to a TFT (Thin Film Transistor) circuit disposed on the transparent substrate 71. The TFT circuit controls the orientation state of the liquid crystal molecules 75 by controlling the voltage between the transparent electrode 78 on the transparent substrate 71 and the transparent electrode 78 on the transparent substrate 72, which serves as a common electrode.

[0093] In this example, the alignment film 79 is configured such that its orientation is at a 45-degree angle to the direction of the transmission axis T1 of the polarizer 15. The liquid crystal molecules held by a pair of alignment films 79 are tilted and aligned according to the orientation direction of the alignment films 79.

[0094] The liquid crystal molecules 75 are rod-shaped liquid crystal molecules with negative dielectric anisotropy, and are oriented approximately perpendicular to the surface of the liquid crystal display element 10 in the absence of voltage. At this time, the liquid crystal molecules 75 have almost no effect on the phase of the light transmitted through the liquid crystal layer 17. That is, the light transmitted through the liquid crystal layer 17 in the absence of voltage does not change its polarization direction and is transmitted through the liquid crystal layer 17.

[0095] For example, such as Figure 1 As shown in Figure A, when the liquid crystal layer 17 is in a voltage-free state, information light L1, with a polarization direction approximately the same as the incident light L0, is incident from the liquid crystal layer 17 onto the phase difference compensation element 20. Since this information light L1 is polarized in a direction perpendicular to the transmission axis T2 of the analyzer 19, it cannot pass through the analyzer 19. Therefore, by setting the pixels of the liquid crystal display element 10 to a voltage-free state, black is displayed (hereinafter, dark display).

[0096] On the other hand, when a voltage is applied between the transparent electrode 78 of the transparent substrate 71 and the transparent electrode 78 of the transparent substrate 72, the liquid crystal molecules 75 tilt toward the alignment direction of the alignment film 79. At this time, the liquid crystal molecules 75 change the phase of the light transmitted through the liquid crystal layer 17 according to their tilt angle. That is, the polarization direction of the light transmitted through the liquid crystal layer 17 changes according to the tilt angle of the liquid crystal molecules 75.

[0097] For example, such as Figure 1 As shown in Figure B, when a voltage is applied to the liquid crystal layer 17, many liquid crystal molecules 75 tilt towards the alignment direction of the alignment film 79. At this time, the light transmitted through the liquid crystal layer 17 changes its polarization direction due to the tilted liquid crystal molecules 75, resulting in information light L2 containing both a polarization component in the same direction as the incident light L0 and a polarization component perpendicular to the incident light L0. This information light L2 is so-called elliptically polarized light, containing a polarization component parallel to the transmission axis T2 of the analyzer 19 and a polarization component perpendicular to it. Only the polarization component parallel to the transmission axis of the analyzer 19 transmits through the analyzer 19. Therefore, by adjusting the pixels of the liquid crystal display element 10 to a suitable voltage, the amount of light transmitted through the analyzer 19 is adjusted, and intermediate grayscale colors are displayed.

[0098] And, for example, such as Figure 1As shown in Figure C, when a sufficient voltage is applied to the liquid crystal layer 17, many liquid crystal molecules 75 are significantly tilted in the alignment direction of the alignment film 79, becoming approximately parallel to the surface of the liquid crystal display element 10. At this time, the light transmitted through the liquid crystal layer 17 changes its polarization direction due to the birefringence of the approximately horizontally aligned liquid crystal molecules 75, becoming information light L3 polarized at an angle of 90 degrees to the incident light L0. Since this information light L3 is polarized in a direction parallel to the transmission axis T2 of the analyzer 19, it is transmitted through the analyzer 19. Therefore, by applying a sufficient voltage to the pixels of the liquid crystal display element 10, the display is brightest (hereinafter, bright display).

[0099] To compensate for the phase difference of the information light transmitted through the liquid crystal layer 17, as described above, a phase difference compensation element 20 is disposed between the liquid crystal layer 17 and the analyzer 19. Details regarding the phase difference compensation element 20 will be described later.

[0100] As described above, when the pixels of the liquid crystal display element 10 are in a voltage-free state, the liquid crystal molecules 75 are oriented approximately perpendicularly to the surface of the liquid crystal display element 10. However, in reality, as... Figure 2 As shown, even in the absence of voltage, the liquid crystal molecules 75 are intentionally tilted approximately 5° from the vertical direction beforehand. This tilting configuration is intended to suppress the generation of alignment defects in the liquid crystal molecules 75, known as the reverse tilt region. The reverse tilt region is a disorder in the alignment state of the liquid crystal molecules 75 caused by the electric field generated by the interaction between adjacent pixels.

[0101] Here, as Figure 2 As shown, the Y2 and Z2 axes are defined in a plane parallel to the surface of the liquid crystal display element 10, and the X2 axis is defined with the direction of light propagation as positive, in a direction perpendicular to the surface of the liquid crystal display element 10, i.e., parallel to the optical axis (transmission optical axis) L0 of the light transmitting through the liquid crystal layer 17. Furthermore, the X2 and Y2 axes are defined to be parallel to the transmission axes of the analyzer 19 and polarizer 15, respectively. Therefore, as... Figure 2 As shown, the angle (azimuth angle) γ between the tilt direction of the liquid crystal molecule 75 and the Y2 axis is 45°.

[0102] At this point, the angle formed by the liquid crystal molecule 75 relative to the Y2-Z2 plane is the tilt angle β of the liquid crystal molecule 75. The tilt angle β varies in the range of approximately 0° to 85° depending on the voltage applied to each pixel. A tilt angle β of approximately 0 degrees indicates that a sufficient voltage is applied to the liquid crystal layer 17, and the liquid crystal molecule 75 is aligned parallel to the Y2-Z2 plane. On the other hand, a tilt angle β of 85 degrees indicates a voltage-free state, where the liquid crystal molecule 75 is aligned approximately perpendicular to the Y2-Z2 plane. In this voltage-free state, the tilt angle β is the pretilt angle, and the liquid crystal molecule 75 is tilted approximately 5° relative to the X2 axis, i.e., the transmission optical axis L0, along the alignment direction of the alignment film 79.

[0103] Furthermore, if the liquid crystal molecules 75 are pre-tilted as described above, even pixels displaying black will experience birefringence due to the pre-tilting of the liquid crystal molecules 75, causing a portion of the light to be transmitted through the analyzer 19. Therefore, a completely black state cannot be displayed, and the contrast of the projected image is reduced. Additionally, the fast axis F caused by the pre-tilting component of the liquid crystal molecules 75 in the liquid crystal layer 17 coincides with the pre-tilting orientation. The fast axis F refers to the axis along the direction of relatively low refractive index and relatively advanced phase of the light in the medium through which the light is transmitted. Hereinafter, the fast axis F caused by the pre-tilting component of the liquid crystal molecules 75 in the liquid crystal layer 17 will be simply referred to as the fast axis F of the liquid crystal layer 17.

[0104] The phase difference compensation element 20 compensates for the phase difference of the information light transmitted through the liquid crystal layer 17 by generating a phase difference that is opposite in phase to the phase difference generated in the liquid crystal display element 10. Therefore, the phase difference compensation element 20 is configured such that its slow axis S coincides with the fast axis F caused by the pre-tilt component of the liquid crystal layer 17. In contrast to the fast axis F, the slow axis S refers to the axis along the direction of relatively high refractive index and relatively delayed phase of the light in the medium through which the light is transmitted. Therefore, when the slow axis S of the phase difference compensation element 20 is aligned with the fast axis F of the liquid crystal layer 17, the phase difference generated by the pre-tilt of the liquid crystal molecules 75 and the phase difference generated by the phase difference plate 21 are opposite in sign, thus compensating for the phase difference generated by the pre-tilt of the liquid crystal molecules 75.

[0105] As a phase difference compensation element 20, a phase difference plate 21 of one embodiment of the present invention can be applied.

[0106] "Phase difference plate of the first embodiment"

[0107] like Figure 3As shown, the retardation film 21 of the first embodiment includes a glass substrate, which is an example of a substrate 23, and a retardation film 25 formed on one side of the substrate 23. The retardation film 25 is an inclined film having a columnar structure 24 that is inclined relative to the normal N of the side on which the retardation film 25 is formed, i.e., the film forming surface 23a. Hereinafter, the retardation film 25 of this example will be referred to as the inclined film 25.

[0108] The tilted film 25 is fabricated by depositing inorganic materials such as Ta2O5 onto the substrate 23 in a tilted direction using a so-called tilted evaporation method. More specifically, as... Figure 4 As shown, with the substrate 23 held in an orientation where the film-forming surface 23a of the substrate 23 is tilted relative to the evaporation source 27, evaporation material from the evaporation source 27 is incident obliquely onto the film-forming surface 23a of the substrate 23 to perform evaporation. Thus, by evaporating the evaporation material onto the film-forming surface 23a of the substrate 23 from an oblique direction, columnar structures 24 inclined relative to the incident direction (hereinafter referred to as the evaporation direction) 28 of the evaporation material relative to the film-forming surface 23a are grown, forming an oblique film 25 with a structure of columnar structures 24. The angle between the evaporation direction 28 and the normal N of the film-forming surface 23a is called the evaporation angle α. Furthermore, when the evaporation source 27 is positioned on a horizontal ground surface, Figure 4 The angle between the horizontal plane (parallel to the horizontal ground) shown by the dashed line and the film forming surface 23a is called the setting angle ω of the substrate 23. That is, the setting angle ω is 0° when the substrate 23 is set horizontally, and the setting angle ω is 90° when the substrate 23 is set perpendicular to the horizontal.

[0109] like Figure 3 As shown, the growth direction, i.e., the length direction 29, of the columnar structure 24 of the inclined film 25 is generally the same as the evaporation direction 28 (see also [reference]). Figure 4 While the growth angle φ formed by the columnar structure 24 and the normal N of the film-forming surface 23a of the substrate 23 is inconsistent, it is positively correlated with the evaporation angle α. That is, the larger the evaporation angle α, the larger the growth angle φ of the columnar structure; the smaller the evaporation angle α, the smaller the growth angle φ of the columnar structure. In fact, compared with the evaporation direction 28, the growth direction 29 of the columnar structure 24 tends to be the direction that rises from the film-forming surface 23a, and the growth angle φ becomes smaller than the evaporation angle α (φ < α). Through the columnar structure formed by the columnar structure 24, the phase retardation film 25 displays refractive index anisotropy as an optical characteristic and functions as an O-plate. In addition, the growth direction 29 of the columnar structure 24 is the length direction of the columnar structure 24. Hereinafter, the growth direction 29 will be referred to as the length direction 29.

[0110] like Figure 5As shown, the refractive index anisotropy of the tilted film 25 is conceptually represented by a refractive index ellipsoid 102 with the three principal refractive indices nx, ny, and nz as axes. Figure 6 A is from Figure 5 The diagram of the refractive index ellipsoid 102 observed along the Y-axis. Figure 6 B is from Figure 5 The diagram of the refractive index ellipsoid 102 observed along the Z-axis. Figure 6 C is from Figure 5 The diagram shows the refractive index ellipsoid 102 viewed along the X-axis. Furthermore, in a refractive index ellipsoid with biaxial birefringence, the principal refractive index refers to the refractive index of the major axis of the refractive index ellipsoid, the refractive index in the direction of the first minor axis perpendicular to the major axis in the ellipse formed by cutting the refractive index ellipsoid along the major axis, and the refractive index in the direction of the second minor axis perpendicular to the aforementioned major axis and first minor axis.

[0111] like Figure 5 and Figure 6 As shown, one of the three principal refractive indices nx, ny, and nz of the refractive index ellipsoid 102 becomes an axis aligned with the length direction 29 of the columnar structure 24. The axis aligned with the length direction 29 of the columnar structure 24 is designated as the X-axis, and the principal refractive index along this X-axis is designated as nx. Furthermore, the major axis direction of the ellipse 104 passing through the center C of the refractive index ellipsoid 102 and perpendicular to the X-axis is designated as the Y-axis, and the minor axis direction is designated as the Z-axis. The principal refractive index along the Y-axis is designated as ny, and the principal refractive index along the Z-axis is designated as nz. In this case, the three principal refractive indices nx, ny, and nz satisfy the following condition (1).

[0112] ny>nx>nz (1)

[0113] Figure 7 Figure A shows the relationship between the incident direction of light relative to the retardation plate 21 and the axes of the refractive index ellipsoid 102 relative to the film surface of the retardation plate 21, which is perpendicular to the incident direction of light. Here, in the retardation plate 21, the normal N of the film forming surface 23a of the substrate 23 is defined as the XS axis, and the YS axis and ZS axis are taken on the film forming surface 23a perpendicular to the XS axis. The axis on which the Y-axis of the refractive index ellipsoid 102 is projected onto the film forming surface 23a is defined as the YS axis, and the direction orthogonal to the YS axis is defined as the ZS axis. In this case, the X-axis of the refractive index ellipsoid 102 lies in the XS-ZS plane and is inclined φ from the XS axis. Furthermore, the ZS axis coincides with the axis on which the X-axis is projected onto the film forming surface 23a.

[0114] When the refractive index ellipsoid 102 is cut by a plane passing through the center C of the refractive index ellipsoid 102 and parallel to the film forming surface 23a, as follows: Figure 7As shown in Figure B, its cross-section is an ellipse 106 with a refractive index nys corresponding to the major axis radius in the YS-axis direction and a refractive index nzs corresponding to the minor axis radius in the ZS-axis direction. Therefore, the tilted film 25 exhibits birefringence with light incident along the XS-axis, having a refractive index nys in the YS-axis direction and a refractive index nzs in the ZS-axis direction. This refractive index nys is greater than the refractive index nzs. That is, the retardation film 25 has a slow axis S1 in the YS-axis direction, which has the maximum refractive index relative to light incident from the XS-axis direction. And, the retardation film 25 has a fast axis F1 in the ZS-axis direction, which has the minimum refractive index relative to light incident from the XS-axis direction. The slow axis S1 is orthogonal to the axis (ZS-axis) that projects the X-axis, which is aligned with the growth direction 29, onto the film-forming surface 23a. That is, when the Y-axis corresponding to the largest principal refractive index ny among the three principal refractive indices nx, ny, and nz is projected onto the film forming surface 23a, and the YS-axis corresponding to the principal refractive index ny with the longest phase delay of the incident light is set as the slow axis, and the axis of the X-axis projected onto the film forming surface 23a is set as the ZS-axis, the slow axis S1 is orthogonal to the ZS-axis.

[0115] Figure 8 A is a diagram of ellipse 107, viewed from the YS axis, showing a section cut off the refractive index ellipsoid 102 by the XS-ZS plane passing through its center C. Furthermore, Figure 8 B is a diagram of ellipse 106, viewed from the XS-axis direction, representing a section of the refractive index ellipsoid 102 cut by a YS-ZS plane passing through its center C. Furthermore, Figure 8 C is a diagram of ellipse 108, which is a cross-section of the refractive index ellipsoid 102 cut by the XS-YS plane passing through the center C, as viewed from the ZS axis.

[0116] Thus, the X and Z axes of the refractive index ellipsoid 102, which displays the refractive index anisotropy of the phase retardation film 25, are rotated by φ with respect to the XS and ZS axes of the phase retardation plate about the YS axis.

[0117] In such a refractive index ellipsoid 102, the phase difference generated in the incident light varies according to the slope of the light incident on the refractive index ellipsoid 102. The phase difference generated in the refractive index ellipsoid 102 depends on the difference between the major and minor axes of an ellipse formed on a section perpendicular to the incident light and passing through the center C of the refractive index ellipsoid 102. With the refractive index along the major axis of this ellipse set as n1, the refractive index along the minor axis as n2, and the optical path length in the inclined film 25 incident perpendicular to this ellipse set as d, the phase difference is represented by Re = (n1 - n2)d. n1, n2, and d all vary according to the incident direction of the light onto the refractive index ellipsoid.

[0118] If the incident angle of light relative to the tilted membrane 25 changes, the incident direction toward the refractive index ellipsoid changes. Therefore, the phase difference generated in the tilted membrane 25 varies depending on the incident angle θ of the light.

[0119] Here, as Figure 9 As shown, taking the XS axis, which is the normal N of the inclined film 25, as a reference, the incident angle in the direction inclined toward the growth direction 29 of the columnar structure 24 is set as positive (+θ), and the incident angle in the direction inclined toward the side of the columnar structure 24 opposite to the growth direction is set as negative (-θ). Furthermore, the phase difference Re(0) relative to the light incident on the inclined film 25 along the XS axis (i.e., light incident at an incident angle of 0°) is called the frontal phase difference. When light is incident on the inclined film 25 from the XS axis, the ellipse of the refractive index ellipsoid on the plane perpendicular to the XS axis, i.e., the YS-ZS plane (refer to...) Figure 8 The phase difference Re(0) is determined by the difference between the refractive index nys along the major axis (YS axis) and the refractive index nzs along the minor axis (ZS axis) and the film thickness d. That is, Re(0) = (nys - nzs)d.

[0120] In the tilted film 25 of this embodiment, the ratio of the phase difference Re(+30) of the incident light at a negative incident angle of +30° to the phase difference Re(-30) of the incident light at a positive incident angle of -30°, i.e., the phase difference ratio Re(30), satisfies the following condition (2).

[0121] Re(30) ratio=Re(30) / Re(-30)=1.1~4.0 (2)

[0122] In the liquid crystal display element 10, the retardation plate 21, which has a tilted film 25 as described above, is arranged such that the slow axis S1 of the tilted film 25 is parallel to the tilt orientation of the liquid crystal molecules 75, that is, parallel to the fast axis F caused by the pre-tilt of the liquid crystal molecules 75. When the retardation plate 21 is used as a phase difference compensation element 20, the slow axis S1 of the tilted film 25 corresponds to the slow axis S in the phase difference compensation element 20. Thus, as described above, the phase difference generated by the pre-tilt of the liquid crystal molecules 75 and the phase difference generated by the retardation plate 21 are opposite in sign to each other, and thus the phase difference can be compensated. However, in a practical liquid crystal display element, the pre-tilted liquid crystal molecules 75 are not the only cause of the phase difference; rather, the phase difference is caused by various factors such as light diffraction caused by the microstructure of the liquid crystal cells and the phase difference generated by the polarizer 15 and the analyzer 19. Therefore, the arrangement of the slow axis S1 of the retardation plate 21 being aligned with the fast axis F of the liquid crystal molecules is not necessarily optimal. Therefore, in order to adjust the orientation of the slow axis S of the phase retarder 21 relative to the fast axis F caused by the pre-tilt of the liquid crystal molecule 75, the phase retarder 21 is rotated around the XS axis to an azimuth angle that can obtain high contrast while observing the contrast of the projected image.

[0123] In conventional tilted films, light scattering sometimes occurs within the tilted evaporation film due to the relaxation of the columnar structure, degrading its quality as a retardation film. Light scattering within the film is evaluated by haze; the greater the haze, the greater the light scattering within the film. If a retardation film with high haze is used as a retardation compensation element 20 in the liquid crystal display element 10, a decrease in the contrast ratio of the liquid crystal display element 10 occurs. This decrease in contrast ratio is caused by the transmission of polarization components in the scattered light generated in the tilted film that are not aligned with the absorption axis of the analyzer 19, leading to a deterioration of the black level. Therefore, to improve contrast ratio, it is preferable to minimize haze.

[0124] The haze of the tilted film 25 can be measured using an integrating sphere. For example... Figure 10 As shown, the integrating sphere 80 has an incident opening 82 and an exit opening 84, which is positioned opposite the incident opening 82 at a position rotated 180° from the incident opening 82. Photodetectors 86 and 88 are respectively disposed in the exit opening 84 and inside the integrating sphere 80. The photodetector 86 disposed in the exit opening 84 receives light that propagates linearly and is transmitted through the integrating sphere from the incident opening 82 along the diameter of the integrating sphere 80. The photodetector 88 disposed inside the integrating sphere 80 receives light that does not propagate linearly and is scattered and reflected within the integrating sphere 80. A phase retarder 21 is disposed in the incident opening 82 such that its surface is perpendicular to the light incident along its diameter. The photodetector 86 detects the vertically transmitted light quantity T1, which is the incident light L that is perpendicularly incident on the surface of the phase retarder 21, passes through the phase retarder 21, and propagates linearly without being scattered by the phase retarder 21, reaching the exit opening. Furthermore, the amount of scattered light T2 in the incident light L, which is scattered by the phase retardation plate 21 and does not propagate in a straight line but is repeatedly reflected within the integrating sphere 80, is detected by the photodetector 88 configured inside the integrating sphere. At this time, the haze [%] of the phase retardation plate 21 is calculated according to the following formula.

[0125] Haze [%] = (T2 / (T1+T2)) × 100

[0126] Furthermore, the haze of the tilted film 25 is obtained by measuring the haze when only the substrate 23 is present using the method described above, and then subtracting the haze when only the substrate is present from the haze of the phase retardation plate 21. Additionally, when the substrate 23 is a glass substrate, the haze is approximately 0.

[0127] The inventors have discovered that in a tilted film 25 with refractive index anisotropy represented by a refractive index ellipsoid 102 satisfying the above equation (1) for principal refractive indices nx, ny, and nz, there is a relationship between the Re(30) ratio and haze as follows: Figure 11The correlation is shown. By making the Re(+30), Re(-30), and Re(30) ratios satisfy the above (2), the haze of the tilted film 25 can be suppressed to below 0.1%. By setting the Re(30) ratio to below 4.0, that is, by suppressing the haze to below 0.1%, when the phase difference compensation element 20 is used as a liquid crystal display element, the contrast ratio can be improved compared to the case where the Re(30) ratio exceeds 4.0.

[0128] By adjusting the substrate setting angle ω during tilted evaporation, a tilted film 25 satisfying equations (1) and (2) above can be fabricated. As an example, in... Figure 4 In the vapor deposition method shown, with the vapor deposition source 27 positioned directly below the center of the substrate 23, multiple tilted films are fabricated by changing the substrate setting angle ω, and the Re(30) ratio is measured. The results show that... Figure 12 The relationship is shown. In this example, tantalum pentoxide (Ta₂O₅) is used as the material for the tilted film 25. Figure 12 As shown, the Re(30) ratio increases with increasing substrate setting angle ω. In this example, by setting the substrate setting angle ω to approximately 85 degrees or less, a Re(30) ratio of 4.0 or less can be obtained. The relationship between the substrate setting angle ω and the Re(30) ratio depends on the structure of the vapor deposition apparatus. Figure 12 The relationship between the Re(30) ratio and the substrate setting angle ω shown varies depending on the vapor deposition apparatus. However, the tendency for the Re(30) ratio to increase with increasing substrate setting angle ω is the same regardless of the structure of the vapor deposition apparatus. Therefore, if the relationship between the two is determined in advance, a tilted film 25 with the desired Re(30) ratio can be obtained.

[0129] The Re(30) ratio satisfies the following condition (2-1).

[0130] Re(30) ratio=Re(30) / Re(-30)=1.2~4.0 (2-1)

[0131] By satisfying condition (2-1), the phase retardation plate 31 (reference) with two tilted films 25 described later can achieve this. Figure 16 In this process, uneven black display can be improved.

[0132] Re(30) is more preferably satisfied by the following condition (2-2).

[0133] Re(30) ratio=Re(30) / Re(-30)=1.4~3.0 (2-2)

[0134] By satisfying condition (2-2), the phase retardation plate 31 (reference) with two tilted films 25 described later can achieve this. Figure 16In this process, uneven black display can be improved, and contrast can be enhanced.

[0135] Re(30) is particularly preferred to satisfy the following condition (2-3).

[0136] Re(30) ratio=Re(30) / Re(-30)=1.5~2.5 (2-3)

[0137] By satisfying condition (2-3), the phase retardation plate 31 (reference) with two tilted films 25 described later can be used. Figure 16 In this process, it can further improve the uniformity of black display and contrast.

[0138] As the material for the tilted film 25, an oxide containing at least one of Si, Nb, Zr, Ti, La, Al, Hf, and Ta can be used. That is, the tilted film 25 can be composed of an oxide containing at least one of Si, Nb, Zr, Ti, La, Al, Hf, and Ta. By using these materials, a tilted film composed of a good columnar structure can be obtained.

[0139] The method of forming the inclined film 25 by inclined vapor deposition has been described, but the method of forming the inclined film 25 is not limited to the above method. Any method that can grow the columnar structure 24 on the film formation surface 23a of the substrate 23 in a direction inclined from the normal N to obtain the inclined film 25 is acceptable. As the vapor deposition method, it is not limited to vacuum vapor deposition, and electron beam vapor deposition or ion plating can be used. Furthermore, chemical vapor deposition (CVD) can also be used. Moreover, sputtering and reactive sputtering methods can also be used.

[0140] In addition, the results of studying the relationship between the three principal refractive indices nx, ny, and nz of the refractive index ellipsoid 102 are explained. The refractive index ellipsoid 102 shows the refractive index anisotropy of the tilted film 25 with a Re(30) ratio of 3 prepared by the above method.

[0141] In the phase difference plate 21 with a tilted film 25 having a Re(30) ratio of 3, the incident angle dependence of the phase difference is as follows: Figure 13 As shown. Additionally, in the measurement... Figure 13 When considering the phase difference, first consider the surface in the refractive index ellipsoid 102 that is orthogonal to the incident light. For example, in Figure 14In the example shown in A, for light incident from the XS-axis direction, the YS-ZS plane is the surface of the refractive index ellipsoid 102 orthogonal to the incident light. Furthermore, for light LX incident from the X-axis direction, the ZY plane is the orthogonal surface. When the incident light is tilted from the XS-axis around the YS-axis, the surface orthogonal to the incident light is tilted around the YS-axis. Therefore, even if the incident direction of the light is tilted from the XS-axis, the radius of the surface orthogonal to the incident light in the YS-axis direction is constant, and the refractive index nys (=ny) expressed in terms of the radius of the YS-axis direction is constant. On the other hand, the radius of the axial direction orthogonal to the YS-axis varies with the incident angle, and therefore the refractive index n(θ) in this axial direction varies with the incident angle θ. The phase difference relative to the incident light is proportional to the difference between the major and minor axes of the ellipse of the refractive index ellipsoid 102 passing through its center C and on the surface orthogonal to the incident light. In this example, the phase difference is determined by subtracting the refractive index n(θ), which varies depending on the incident angle, from the reference refractive index nys.

[0142] like Figure 13 As shown, in this tilted membrane 25, the phase difference increases as the incident angle θ increases in the positive direction, and becomes a roughly constant phase difference when the incident angle θ is 30° or higher. On the other hand, the phase difference decreases as the incident angle θ increases in the negative direction, and the phase difference is 0 when the incident angle θ is 50°.

[0143] In addition, if using Figure 5 As explained, the X-axis of the principal refractive index nx of the refractive index ellipsoid 102 is parallel to the growth direction 29 of the columnar structure 24 (reference). Figure 3 Consistent. Therefore, as Figure 14 As shown in Figure A, when light LX is incident on the tilted film 25 along the X-axis, it becomes perpendicular to the YZ plane of the refractive index ellipsoid 102. Therefore, light LX incident on the tilted film 25 along the X-axis is subjected to... Figure 14 The ellipse 104 shown in Figure B represents the effect of the refractive index. In this case, the phase difference generated by the incident light LX on the tilted film 25 is represented by Re(φ) = (ny-nz)d1, based on the relationship between the principal refractive indices ny and nz in the refractive index ellipsoid 102 and the optical path length d1 in the tilted film 25. Furthermore, d1 = d / cosφ.

[0144] Furthermore, when light LZ is incident on the inclined film 25 along the Z-axis, which is orthogonal to the X-axis, it becomes perpendicular to the XY plane of the refractive index ellipsoid 102. Therefore, light LZ incident on the inclined film 25 along the Z-axis direction is subjected to... Figure 14The ellipse 103 shown in Figure C represents the effect of the refractive index. In this case, the phase difference generated by the light LZ incident on the tilted film 25 is represented by Re(φ-90)=(ny-nx)d2, based on the relationship between the principal refractive indices ny and nx in the refractive index ellipsoid 102 and the optical path length d2 in the tilted film 25. Furthermore, d2=d / cos(φ-90).

[0145] Transmission electron microscopy was performed on the phase contrast plate 21, and the growth angle φ of the columnar structure 24 of the tilted film 25 was observed (reference). Figure 3 The angle is 45°. That is, at... Figure 13 In the equation, the phase difference Re(+45) at a normal incident angle θ = 45° is caused by the difference between the principal refractive indices ny and nz in the refractive index ellipsoid 102. Furthermore, in... Figure 13 In the equation, the phase difference Re(-45) at a negative incident angle θ = 45° is caused by the difference between the principal refractive indices ny and nx in the refractive index ellipsoid 102.

[0146] according to Figure 13 Given the relationship Re(+45) > Re(-45), (ny-nz)d1 > (ny-nz)d2. Here, when φ = 45°, d1 = d2, therefore ny-nz > ny-nz. Furthermore, since (ny-nz)d1 > 0 and (ny-nx)d2 > 0, therefore... Figure 13 The inclined membrane 25 in the example shown satisfies ny>nx>nz.

[0147] Here, we will use experimental example 1 to illustrate the function of phase difference plate 21.

[0148] [Experimental Example 1]

[0149] A tilted film with a frontal phase difference Re(0) of 23 nm was formed on a glass substrate by tilted evaporation. Ta2O5 was used as the material for the tilted film. By changing the substrate setting angle ω to change the evaporation angle, phase difference plates with various Re(30) ratios were fabricated, namely samples 1-1 to 1-11.

[0150] It uses the optical engine of commercially available LCD projectors, such as... Figure 1As shown, a liquid crystal display element 10 structure is configured with a phase retardation plate and an analyzer 19, arranged sequentially as a polarizer 15, a liquid crystal layer 17, a phase retardation compensation element 20, and a phase retardation plate for each sample. A screen is positioned at the location where light passing through the analyzer 19 is projected, and white and black displays are performed on the screen. Contrast ratio and black display uniformity are evaluated according to the following criteria. At this time, the slow axis of the tilting film is aligned with the fast axis F caused by the pre-tilting component of the liquid crystal layer 17. In this example, the fast axis caused by the pre-tilting component of the liquid crystal layer 17 is at a 45° orientation, and the slow axis S of the tilting film of the phase retardation plate is aligned with the 45° orientation.

[0151] Regarding contrast, the illuminance value of a white display was measured when the illuminance of a black display was set to 1, and the measured values ​​were evaluated as follows.

[0152] A: More than 2000

[0153] B: 1500 or higher but less than 2000

[0154] C: 1000 or higher but less than 1500

[0155] D: Less than 1000

[0156] In addition, in this structure, the black display ratio is 800:1 when the phase difference compensation element 20 is not present.

[0157] Regarding uneven black display, such as Figure 15 As shown, the illuminance of the black display at points A, B, C, and D at the four corners of screen 90 and point E at the center of screen 90 was measured and calculated as follows.

[0158] Uneven black display = ((A+D)-(B+C)) / E

[0159] The calculated values ​​for uneven black display were evaluated as follows.

[0160] A: Below 2

[0161] B: More than 2 and less than 4

[0162] C: More than 4 and less than 6

[0163] D: More than 6

[0164] Furthermore, for the evaluation results of contrast and black unevenness, evaluation A was set to 7 points, evaluation B to 5 points, evaluation C to 3 points, and evaluation D to 0 points. For each embodiment, a comprehensive score was calculated by adding the scores for contrast and black unevenness. The higher the comprehensive score, the better the quality of the phase difference film. The results are shown in Table 1 below.

[0165] [Table 1]

[0166] sample Re(30) ratio Contrast Uneven black display Overall score 1-1 1 D B 5 1-2 1.1 C B 8 1-3 1.5 C B 8 1-4 2 C B 8 1-5 2.5 C C 6 1-6 3 C C 6 1-7 3.5 C C 6 1-8 4 C C 6 1-9 4.5 D C 3 1-10 5 D C 3 1-11 5.5 D D 0

[0167] The samples 1-2 to 1-8 shown in Table 1, with Re(30) values ​​of 1.1 to 4, correspond to embodiments of the phase retardation film of the present invention. Additionally, sample 1-1, with a Re(30) value of 1, exhibits uniaxial refractive index anisotropy with ny = nz and is a comparative example. Compared to other samples, samples 1-2 to 1-8 demonstrate higher contrast evaluation, achieving a significant improvement in contrast. Furthermore, they exhibit a high combined score for contrast and black display unevenness, resulting in improved contrast and suppression of black display unevenness. Moreover, in the samples with Re(30) values ​​of 1.1 to 2.0, further improvements in contrast and suppression of black display unevenness were achieved.

[0168] "Phase difference plate of the second embodiment"

[0169] The phase retardation plate used as the phase difference compensation element 20 is not limited to a structure with only one layer of inclined film 25 as described in the phase retardation plate 21 above; it can also be provided with two or more layers of inclined film 25. As a phase retardation plate of the second embodiment, a phase retardation plate 31 having two layers of inclined film will be described.

[0170] like Figure 16 As shown, the phase retardation film 31 of this embodiment has a first inclined film 25a on one side of the substrate 23 and a second inclined film 25b formed on the other side. That is, in the phase retardation film 31, an inclined film is formed on each of the two sides of the substrate.

[0171] In this embodiment, the first tilted film 25a and the second tilted film 25b are manufactured in the same manner as the tilted film 25 described above, and their optical properties are also the same. That is, the first tilted film 25a and the second tilted film 25b, like the tilted film 25, have refractive index anisotropy represented by the refractive index ellipsoid 102 that satisfies the principal refractive indices nx, ny, and nz as described in equation (1) above. Furthermore, the ratios Re(+30), Re(-30), and Re(30) satisfy equation (2) above.

[0172] Since the first tilted film 25a and the second tilted film 25b satisfy equations (1) and (2) respectively, the haze can be suppressed to below 0.1%. When two tilted films 25a and 25b are stacked, the haze is accumulated, and therefore the haze of the phase difference plate 31 increases. However, by making each tilted film 25a and 25b satisfy equations (1) and (2) respectively, the haze during stacking can also be suppressed, and the haze during stacking can be reduced to below 0.3% (see below). Figure 28If the phase difference film has a haze of less than 0.3% when it has two or more tilted films 25a and 25b, then when it is used as a phase difference compensation element 20 for a liquid crystal display element, it can improve the contrast ratio and suppress black display unevenness compared to the case where the Re(30) ratio exceeds 4.

[0173] In the phase difference plate 31, the first tilted film 25a and the second tilted film 25b are arranged in a manner that is approximately orthogonal to the slow axis S21 of the first tilted film 25a and the slow axis S22 of the second tilted film 25b, with an intersection angle of 90°±3°.

[0174] As described above, in the retardation plate 21 with a single-layer tilted film 25, the slow axis S1 of the tilted film 25 is arranged parallel to the fast axis F of the liquid crystal layer 17 in the liquid crystal display element 10. In the case of the retardation plate 31 with two tilted films 25a and 25b, the combined slow axis S2, formed by combining the slow axis S21 of the first tilted film 25a and the slow axis S22 of the second tilted film 25b, is arranged parallel to the fast axis F of the liquid crystal layer 17. Therefore, the phase difference generated by the pre-tilting of the liquid crystal molecules 75 and the phase difference generated by the retardation plate 31 are opposite in sign, thus compensating for the phase difference generated by the pre-tilting.

[0175] For example, such as Figure 17 As shown in Figure A, in the liquid crystal display element 10, when the fast axis F of the tilt component of the liquid crystal layer 17 is at a 45° orientation, the slow axis S21 of the first tilt film 25a is aligned with a 90° orientation, and the slow axis S22 of the second tilt film 25b is aligned with a 0° orientation. With this configuration, the combined slow axis S2, formed by combining the slow axes S21 and S22, is at a 45° orientation, aligned with the fast axis F.

[0176] Here, the intersection angle of the slow axes of the first inclined membrane 25a and the second inclined membrane 25b is studied. According to the research of the inventors, it is preferable that the intersection angle deviates slightly from 90°. More preferably, the deviation is within ±5° relative to 90°, and even more preferably within ±3°. The reasons for this will be explained below.

[0177] First, refer to Figure 18 The in-plane optical anisotropy of the tilted film 25 is explained. For example... Figure 18 As shown in Figure A, within the plane of the inclined film 25, the evaporation direction 28 (reference) is... Figure 3 and Figure 4 Projected onto the film forming surface 23a (reference) Figure 3The axis on the slow axis S1 is orthogonal to the slow axis S1. Furthermore, the axis projected onto the film forming surface 23a from the evaporation direction 28 is aligned with the axis projected onto the film forming surface 23a from the growth direction 29. The fast axis F1, orthogonal to the slow axis S1, is set to an orientation of 0°-180°. Figure 18 B is along Figure 18 A shows the cross-section of the fast axis F1 of the inclined membrane 25. Figure 18 C is along Figure 18 A shows the cross-section of the inclined membrane 25 along the slow axis S1. The columnar structure 24 is inclined in the cross-section along the fast axis F1. Therefore, even if the incident angle θ is the same, the phase difference experienced by the light passing through the columnar structure 24 will be different if the azimuth of the incident angle is different. In addition, the phase difference at the incident angle θ and the azimuth angle η will sometimes be denoted as Re(θ)η. For example, the phase difference at the incident angle of 15° and the azimuth angle of 90° is called Re(15)90°. In addition, in Figure 9 The phase difference Re(θ) of incident light with respect to the angle of incidence θ tilted from the normal to the growth direction, as described in this statement, is Re(θ)180, and the phase difference Re(-θ) of incident light with respect to the angle of incidence θ tilted from the normal to the side opposite to the growth direction, as described in this statement, is Re(θ)0.

[0178] Furthermore, the orientation of the liquid crystal display element 10 in this example is as follows: Figure 17 As shown, the fast axis caused by the pre-tilt of the liquid crystal molecules 75 in the liquid crystal layer 17 is determined to be at a 45° orientation, which is different from the orientation described in the single-layer tilt film. Hereinafter, the orientation of the phase retardation plate 31 follows the orientation in the liquid crystal display element 10.

[0179] As described above, in the liquid crystal display element 10, the phase difference plate 31 is configured such that the combined slow axis S2 of the slow axes S21 and S22 of the first tilt film 25a and the second tilt film 25b is at a 45° orientation.

[0180] The phase difference Re(θ) between the first tilted membrane 25a and the second tilted membrane 25b is azimuth-dependent. Furthermore, the phase difference Re(θ) of the phase difference plate 31 formed by stacking the two membranes is the sum of the phase differences between the first tilted membrane 25a and the second tilted membrane 25b.

[0181] When the first inclined membrane 25a and the second inclined membrane 25b are configured such that their slow axes intersect at a 90° angle, in Figure 19 The diagram schematically illustrates the azimuth dependence of the phase differences Re(0) and Re(15) within the 45° ± 45° range of the phase difference plate 31, i.e., from 0° to 90°. In this case, as... Figure 19As shown, the frontal phase difference Re(0) of the phase difference plate 31 is canceled by the orthogonally arranged first tilted film 25a and second tilted film 25b, becoming zero in the 0° to 90° orientation.

[0182] The liquid crystal layer 17 has a frontal phase difference component due to its pre-tilted component at the 45° azimuth, which has a peak at the 45° azimuth and exhibits a roughly symmetrical azimuth dependence within a range of ±45°. However, when the two tilted films 25a and 25b are arranged at an angle of 90° to each other's slow axis, the Re(0)45 of the phase difference plate 31 is zero, thus it is impossible to compensate for the frontal phase difference of the liquid crystal layer 17.

[0183] On the other hand, when the slow axes of the first inclined membrane 25a and the second inclined membrane 25b are configured to be slightly offset from each other by 90°, Figure 20 The diagram schematically illustrates the azimuth dependence of the phase differences Re(0) and Re(15) within the 45° ± 45° range of the phase difference plate 31, i.e., from 0° to 90°. In this case, as... Figure 20 As shown, the frontal phase difference Re(0) of the retardation plate 31 exhibits an azimuth dependence with a peak at the 45° azimuth. In the retardation plate 31, by making the frontal phase difference Re(0) at the 45° azimuth approximately 0.1 nm to 5 nm, it is possible to set a phase difference of the same magnitude as the frontal phase difference at the fast axis of the liquid crystal layer 17, thus effectively compensating for the frontal phase difference at the 45° azimuth of the liquid crystal layer. That is, as the retardation plate 31, it is preferable that the frontal phase difference Re(0) at the slow axis azimuth is 0.1 nm to 5 nm.

[0184] Furthermore, as an example, regarding the phase retarder 31 provided by stacking the first and second inclined films 25a and 25b, the relationship between the intersection angle of the slow axes of each of the two inclined films 25a and 25b and the Re(0)45 and Re(15)45 of the phase retarder at the 45° orientation is as follows: Figure 21 As shown. In Figure 21 In this context, the case where the slow axis is orthogonal is set to 0°, the case where the cross angle is greater than 90° is set to positive, and the case where the cross angle is less than 90° is set to negative. Here, as a monolayer tilted film, a tilted film with Re(0) = 32 nm and a Re(30) ratio = 2.5 is used. Furthermore, the Re(0) and Re(30) ratios of the monolayer tilted film are determined according to the following... Figure 9 Definition of the description.

[0185] like Figure 21As shown, by changing the slow axis from an orthogonal state by ±10°, the front phase difference Re(0) of the retardation plate 31 can be varied within the range of zero to ±10 nm. Similarly, the phase difference Re(15) of the retardation plate 31 also varies within the range of ±10 nm from the value (9 nm) in the orthogonal state. The cross angle of the slow axis of the two stacked tilted films 25a and 25b can be set according to the front phase difference Re(0) of the liquid crystal layer 17 at a 45° orientation in the applicable liquid crystal display element 10.

[0186] Furthermore, according to the inventors' research, the deviation of the slow axis of the first inclined membrane 25a and the second inclined membrane 25b from each other from 90° is preferably within ±5°, and more preferably within ±3°.

[0187] As described above, the liquid crystal layer 17 has a front-side phase difference component due to its pre-tilt component at the 45° azimuth, which has a peak value at the 45° azimuth and exhibits a roughly symmetrical azimuth dependence within a range of ±45°. Furthermore, in the liquid crystal layer 17, the phase difference Re(θ) incident at other incident angles θ also has a peak value at the 45° azimuth and exhibits a roughly symmetrical azimuth dependence within a range of ±45°. To effectively compensate for the phase difference generated in the liquid crystal layer 17, it is preferable to have a phase difference with the opposite phase to the phase difference of the liquid crystal layer within a range of ±45° at the 45° azimuth. That is, it is preferable that the phase difference Re(θ) of the phase difference plate 31 is roughly symmetrical around the 45° azimuth within a range of ±45° at the 45° azimuth. The difference between the phase difference Re(15)90 at the 90° azimuth (45° + 45°) and the phase difference Re(15)0 at the 0° azimuth (45° - 45°) serves as an indicator of symmetry. The smaller this difference, the higher the symmetry with respect to the 45° azimuth. Specifically, in the phase difference plate 31, it is preferable that the phase difference between the phase difference Re(15)90 and the phase difference Re(15)0 is within ±6nm.

[0188] Typically, the phase difference Re(θ) of the retardation plate 31 exhibits a maximum positive peak value in one orientation of the synthesized slow axis S2. To efficiently compensate for the phase difference in the liquid crystal layer 17, the orientation of the synthesized slow axis representing the maximum peak value is configured to coincide with the fast axis F of the liquid crystal layer 17. Here, in the retardation plate 31, the azimuth angle at which the phase difference Re(15) generated for incident light with an incident angle of +15° relative to the normal is maximized in the azimuth angle from 0° to 360° is set as the reference azimuth angle ηa. The retardation plate 31 is configured such that if the fast axis of the liquid crystal layer 17 is in the azimuth angle of 45°, then the reference azimuth angle ηa becomes 45°. That is, the absolute value of the difference between the first phase difference Re(15)ηa+45 of the incident light with an azimuth angle relative to the reference azimuth angle ηa+45° and the second phase difference Re(15)ηa-45 of the incident light with an azimuth angle relative to the reference azimuth angle ηa-45° is preferably 6 nm or less.

[0189] Centered on the azimuth angle ηa where the phase difference Re(15) is the largest, the difference between the phase difference Re(15)ηa+45 and the phase difference IRe(15)ηa-45 at the azimuth angle ηa-45° is within ±6nm, indicating that the symmetry of the phase difference plate 31 is high within the azimuth angle range of ηa±45° centered on the azimuth angle ηa. If the symmetry of the phase difference plate 31 is high within the azimuth angle range of ηa±45° centered on the azimuth angle ηa, then a phase difference plate with opposite phases within a range of ±45° centered on the azimuth angle-dependent fast axis of the liquid crystal layer can be realized. In the liquid crystal layer 17, since the phase difference is largest within the range of ±45° of the pre-tilt azimuth, as long as the phase difference plate 31 displays the opposite phase within this range, the phase difference of the liquid crystal layer 17 can be effectively compensated. Therefore, when such a phase difference sheet 31 is applied to the phase difference compensation element 20 of the liquid crystal display element 10, the contrast can be effectively improved and the unevenness of black display can be suppressed.

[0190] Furthermore, the above description assumes that the two tilted films 25a and 25b have the same refractive index anisotropy, but their refractive index anisotropy may not be exactly the same. However, it is preferable that the difference ΔRe(0) between the frontal phase difference Re(0) of the first tilted film 25a and the second tilted film 25b is 3 nm or less.

[0191] For a phase retardation plate 31 formed by stacking two inclined films 25a and 25b, the difference ΔRe(0) between the frontal phase differences Re(0) of the first inclined film 25a and the second inclined film 25b and the phase retardation plate 31 have the largest azimuth (peak azimuth). As an example, it is located in the position of... Figure 22The relationship is shown. Here, "I" is the phase difference of the phase difference plate 31, which is assigned to distinguish it from the phase differences of each tilting film 25a, 25b.

[0192] The results of studying the relationship between the peak orientations of ΔRe(0) and IRe(15) are shown in Figure 22 .like Figure 22 As shown, when ΔRe(0) is zero, the peak orientation of IRe(15) coincides with the fast axis orientation, i.e., the 45° orientation, caused by the pre-tilt component of liquid crystal layer 17. On the other hand, if ΔRe(0) is less than zero, the peak orientation of IRe(15) increases, and if ΔRe(0) is greater than zero, the peak orientation of IRe(15) decreases. Since the peak orientation of IRe(15) deviates from the 45° orientation, the efficiency of phase difference compensation may decrease.

[0193] Furthermore, the peak value of the phase difference IRe(15) between ΔRe(0) and the phase difference plate 31 in the 0-360° orientation, IRe(15)max, is in the position of... Figure 23 The relationship shown. For example... Figure 23 As shown, IRe(15)max is approximately 9 nm when ΔRe(0) is zero, which is its minimum. Conversely, IRe(15)max increases as the absolute value of ΔRe(0) increases. In this case, overcompensation of the phase difference occurs, and the efficiency of phase difference compensation may decrease.

[0194] Furthermore, the difference between ΔRe(0) and IRe(15) at ±45° of the orientation of the synthesized slow axis S2 of phase difference plate 31, that is, ΔIRe(15) as the difference between IRe(15)90 and IRe(15)0, is in the position of... Figure 24 The relationship is shown. ΔIRe(15) approaching 0 indicates high symmetry within a range of ±45° centered on the orientation of the synthesized slow axis S2. In the liquid crystal layer 17, a large phase difference is generated within a range of ±45° centered on the orientation of the fast axis F caused by the pre-tilting component. Furthermore, the phase difference generated in the liquid crystal layer 17 is symmetrical within a range of ±45° centered on the orientation of the fast axis F. Therefore, it is considered that the higher the symmetry of the phase difference plate 31 within a range of ±45° centered on the orientation of the synthesized slow axis S2, the higher the efficiency of phase difference compensation.

[0195] That is, in order to compensate for the phase difference of the liquid crystal layer 17 with a pre-tilted component at the 45° position, it is preferable that the peak position of IRe(15) is near the 45° position, and the symmetry is high within the range of ±45° at the 45° position. Therefore, the difference ΔRe(0) between the front phase differences of the two tilted films 25a and 25b is preferably within ±3nm, more preferably within ±1nm, and most preferably the difference between the front phase differences is 0.

[0196] "Design Change Example"

[0197] refer to Figures 25-32 An example of a design modification for a phase retardation plate with two tilted films will be explained. Additionally, in Figure 16 and Figures 25-32 In this context, the same symbols are used to mark the same elements.

[0198] In the phase difference plate 31 of the second embodiment described above, such as Figure 25 As shown, antireflective films 41 and 42 are preferably provided on both sides of the substrate 23, and antireflective films 43 and 44 are provided on the side of the first inclined film 25a and the side of the second inclined film 25b, which are the outermost surfaces of the phase retardation plate 31, respectively. By providing antireflective films 41, 42, 43, and 44, the reflection of incident light at each interface can be suppressed, the transmittance can be improved, and the haze suppression effect can be further improved.

[0199] The phase retardation plate 31 of the second embodiment has a first inclined film 25a on one surface of the substrate 23 and a second inclined film 25b on the other surface. Alternatively, two or more inclined films 25 can be stacked, as shown in the example. Figure 26 As shown in the phase retardation plate 32, two inclined films 25a and 25b are formed on one side of the substrate 23. However, as... Figure 16 As shown, each side of the substrate 23 has a tilted film 25a and 25b, which can suppress scattering at the interface when the tilted films 25a and 25b are directly stacked, thereby suppressing haze, and is therefore preferred.

[0200] When two inclined films 25a and 25b are stacked on one side of substrate 23, the same applies. Figure 19 As shown, antireflective films 45, 46, and 47 are preferably provided on both sides of the substrate 23 and on one side of the second inclined film 25b, which forms the outermost surface of the phase retardation plate 32. By providing antireflective films 45, 46, and 47, the reflection of incident light at the interface can be suppressed, the transmittance can be improved, and the haze suppression effect can be further enhanced.

[0201] Here, the haze of the phase difference plate, which is set by stacking two inclined films 25, will be explained.

[0202] exist Figure 12 In the data shown, a phase retardation plate with two tilted films was fabricated under the condition that the tilted films were fabricated with the same substrate setting angle ω of 35°, 50°, 75°, and 90°. Here, a phase retardation plate 31 with a tilted film formed on each of the two sides of the substrate is fabricated (see reference). Figure 16 ) and a phase retardation plate 32 formed by stacking two inclined films on one side of a substrate (reference) Figure 26 The haze of each substrate was measured. The relationship between haze and substrate setting angle ω is shown in the figure. Figure 28Furthermore, after the first tilted film 25a is deposited on each of the phase retardation plates 31 and 32, a second tilted film 25b is formed while the substrate is rotated approximately 90°, and the slow axes S21 and S22 of the first tilted film and the second tilted film are approximately orthogonal to each other (see reference). Figure 16 , Figure 26 Furthermore, the structure is configured such that any one of antireflective films 41 to 47 is provided on both sides of the substrate and on the outermost surface of the retardation plate (see reference). Figure 25 , Figure 27 ).

[0203] exist Figure 28 In the figure, the values ​​in parentheses represent the Re(30) ratio for the tilted membrane 25 of the single membrane. Figure 28 As shown, if the Re(30) ratio is below 4, the haze can be suppressed to approximately 0.3% or less. Furthermore, from... Figure 28 It can be seen that, compared with a phase retardation plate 32 formed by stacking two layers on a single side, the phase retardation plate 31 with two tilted films 25a and 25b separately formed on both sides of the substrate exhibits lower haze regardless of the Re(30) ratio. In the phase retardation plate 31 with two tilted films 25a and 25b separately formed on both sides of the substrate, if the Re(30) ratio is 4 or less, the haze can be suppressed to approximately 0.2% or less. As described above, it is believed that by forming one tilted film 25a and 25b on each side of the substrate, and stacking the two tilted films 25a and 25b in direct contact, the effect of suppressing scattering generated at the interface of the two tilted films 25a and 25b is achieved.

[0204] Furthermore, regarding the phase retarder 32 provided by stacking two inclined films 25a and 25b on one side, such as... Figure 29 As shown, a planarization layer 26 is preferably provided between the first inclined film 25a and the second inclined film 25b.

[0205] Planarization layer 26 is an example of an intermediate layer. Planarization layer 26 has the function of planarizing the fine irregularities generated on the surface of the previously formed first tilted film 25a. As planarization layer 26, it is not limited to silicon oxide film (SiO2), but can also be an oxide metal such as tantalum pentoxide (Ta2O5) or magnesium fluoride (MgF2). For example, planarization layer 26 is not formed by tilted evaporation, but by placing a evaporation source directly below the substrate and performing front-side evaporation.

[0206] By providing a planarization layer 26 between the first tilted film 25a and the second tilted film 25b, the fine irregularities on the surface of the first tilted film 25a are planarized, allowing the second tilted film 25b to be formed into a flat surface. Thus, by having the planarization layer 26 on the surface of the first tilted film 25a, the surface roughness of the film-forming surface of the second tilted film 25b is reduced, thereby suppressing scattering at the interface and thus suppressing the haze of the phase retardation film 32. Furthermore, compared to the case where the second tilted film 25b is formed directly on the first tilted film 25a, the improvement in black level uniformity and contrast is significantly greater.

[0207] For the phase retardation plate 32 with a planarization layer 26 of 15 nm silicon oxide film disposed between the tilted films 25a and 25b (reference) Figure 29 The relationship between haze and substrate setting angle ω is shown in... Figure 30 .exist Figure 30 In the diagram, black triangles represent data related to the phase difference plate 32 with planarization layer 26. Furthermore, for comparison... Figure 30 China also stated Figure 28 The data shown. For example... Figure 30 As shown, when tilted films 25a and 25b are stacked on one side of a substrate, the phase retardation plate 31 with a planarization layer 26 disposed between the tilted films 25a and 25b can significantly reduce haze compared to the phase retardation plate 32 which is stacked by bringing the tilted films 25a and 25b into contact. If the Re(30) ratio is 4 or less, the haze can be suppressed to approximately 0.25% or less.

[0208] The preferred film thickness for the planarization layer 26 was investigated as follows. Figure 29 In the phase retardation sheet 32 ​​of the layered structure shown, samples with film thicknesses varying from 5 nm to 30 nm were fabricated using SiO2, Ta2O3, or MgF2 as the planarization layer 26. A film with a Re(30) ratio of 2.0 was used as the tilted film. The haze of these samples was measured and compared with the haze H0 of a phase retardation sheet with equally tilted films on both sides of the substrate, and the evaluation was performed as follows.

[0209] A: Less than 1.2 times the haze H0

[0210] B: Haze H0 is more than 1.2 times but less than 1.5 times.

[0211] C: More than 1.5 times the haze H0

[0212] The evaluation results are shown in Table 2.

[0213] [Table 2]

[0214]

[0215] In Table 2, the refractive index is a value relative to a wavelength of 400 nm. As shown in Table 2, the preferred optical path length for the thickness of the planarization layer 26 is approximately 40 nm, which is approximately 1 / 10 or less relative to a wavelength of 400 nm. Furthermore, by setting the physical film thickness to 10 nm or more, the surface of the tilted film can be planarized, thereby improving the effect of suppressing scattering.

[0216] In the above embodiments and design variations, the retardation plate, which is provided as a stacked two-layer inclined film 25a, 25b, is described in a manner in which one layer is formed on each side of a substrate 23 or two layers are formed on one side. The retardation plate provided as a stacked two-layer inclined film 25a, 25b can also be a phase plate having two substrates on which two inclined films are formed respectively. For example, as... Figure 31 As shown, a phase retardation film 35 can also be formed by overlapping a first phase retardation film 35a on a first substrate 22a and a second phase retardation film 35b on a second substrate 22b. In this specification, the arrangement of stacking two or more tilted films includes not only stacking multiple tilted films 25a and 25b on a single substrate 23, but also overlapping tilted films 25a and 25b formed on different substrates 22a and 22b in the optical path.

[0217] like Figure 31 As shown, as long as the phase retardation plate 35 has a first phase retardation plate 35a having a first tilted film 25a formed on the first substrate 22a and a second phase retardation plate 35b having a second tilted film 25b formed on the second substrate 22b, the rotation angles of their fast axes S31 and S32 can be changed by rotating one of them relative to the other about the XS axis during assembly, depending on the applicable liquid crystal display element 10. In the liquid crystal display element 10, for the phase differences Re(0) and Re(15) of the liquid crystal layer 17 that have manufacturing deviations, phase difference compensation can be performed in the most efficient way, that is, in a way that maximizes contrast performance, and each can be individually addressed. Thus, in the liquid crystal display element 10 having the liquid crystal layer 17 and the phase difference compensation element 20, by rotating at least one of the multiple substrates 22a and 22b on which at least one phase retardation film is formed about the XS axis perpendicular to the film formation surface relative to the other substrates 22a, the contrast of the liquid crystal display element 10 can be adjusted.

[0218] In the above description, phase retardation plates 31, 32, and 36 formed by stacking two inclined films 25 have been explained. However, the phase retardation plates of the present invention can also be formed by stacking three or more inclined films 25. For example, as Figure 32As shown, a phase difference sheet 36, which has tilted films 25a and 25b on one side of the substrate 23 and tilted film 25c on the other side, can also be used as a phase difference compensation element 20. The phase difference sheet 36 has anti-reflective films 41, 42, 43, and 44 on both sides of the substrate 23 and on the outermost surface of the phase difference sheet 36, respectively.

[0219] In the case of a phase retardation plate 36 having three tilted films 25, the slow axis S3, formed by combining the slow axis S21 of the first tilted film 25a, the slow axis S22 of the second tilted film 25b, and the slow axis S23 of the third tilted film 25c, is arranged parallel to the fast axis F of the liquid crystal layer 17. Therefore, the phase difference generated by the pre-tilting of the liquid crystal molecules 75 and the phase difference generated by the phase retardation plate 36 are opposite in sign to each other, thus compensating for the phase difference generated by the pre-tilting.

[0220] For example, such as Figure 33 As shown, when the fast axis F of the tilt component of the liquid crystal layer 17 is at a 45° orientation, the first tilt film 25a and the second tilt film 25b are arranged such that the combined slow axis S22 of the slow axis S21 of the first tilt film 25a and the slow axis S22 of the second tilt film 25b is at a 0° orientation. Furthermore, the third tilt film 25c is arranged such that its slow axis S23 is at a 90° orientation. This allows the combined slow axis S3, which further synthesizes the combined slow axis S2 and slow axis S23, to be aligned with the orientation of the fast axis F of the tilt component of the liquid crystal layer 17. Thus, even when two or more tilt films 25a, 25b, and 25c are provided, the same phase difference compensation as in the case of two tilt films 25a and 25b can be performed.

[0221] On the other hand, in the case of a tilted film with three or more layers, the symmetry of the phase difference azimuth dependence of the phase difference as a retardation plate, centered at 45° azimuth ± 45°, tends to decrease compared to a retardation plate with two tilted layers. As mentioned above, the azimuth dependence of the phase difference caused by the pre-tilted component of the liquid crystal layer is symmetrical about 45° azimuth within the range of 45° azimuth ± 45°. Therefore, if the symmetry decreases, the effect of phase difference compensation decreases. Therefore, in order to obtain high symmetry, it is preferable to make the tilted film two layers. Even with three or more layers, as long as the phase difference between the phase difference Re(15)90 and the phase difference Re(15)0 in the retardation plate 36 is within ±6nm, the effect of phase difference compensation can be sufficiently obtained. When applied to a liquid crystal display element, this can improve contrast and suppress uneven black display.

[0222] Here, we will use experimental examples 2 to 4 to illustrate the function of phase difference plates 31, 32, and 33.

[0223] [Experimental Example 2]

[0224] Made Figure 25 The layered phase retardation films shown are samples 2-1 to 2-13. A tilted film with a front-side phase difference Re(0) of 23 nm was formed on each side of a glass substrate with antireflective films on both sides by tilted evaporation. At this time, the slow axes of the two tilted films intersect at a 93° angle. Furthermore, an antireflective film is formed on the surface of the tilted film. Ta2O5 was used as the material for the tilted film. By changing the substrate setting angle ω to change the evaporation angle, phase retardation films with different Re(30) ratios were fabricated, namely samples 2-1 to 2-13. The tilted films stacked in a single sample have the same Re(30) ratio.

[0225] For samples 2-1 to 2-13, contrast and black level uniformity were evaluated and scored using the same method as in Experiment 1. The results are shown in Table 3.

[0226] [Table 3]

[0227] sample Re(30) ratio Contrast Uneven black display Overall score 2-1 1 D A 7 2-2 1.2 D A 7 2-3 1.4 C A 10 2-4 1.5 B A 12 2-5 1.6 B A 12 2-6 2 B A 12 2-7 2.3 B A 12 2-8 2.5 B A 12 2-9 3 C A 10 2-10 3.5 C B 8 2-11 4 C B 8 2-12 4.5 D D 0 2-13 5 D D 0

[0228] The samples 2-2 to 2-11 shown in Table 3 correspond to embodiments of the phase difference film of the present invention. Compared with the samples with Re(30) exceeding 4, the samples of the embodiments with Re(30) of 1.2 to 4 have higher contrast ratings, achieving a significant improvement in high contrast. Furthermore, the samples with Re(30) of 1.4 to 3.0 achieve higher contrast and better suppression of black display inhomogeneity, and the samples with Re(30) of 1.5 to 2.5 achieve even better results.

[0229] [Experimental Example 3]

[0230] Made Figure 27 The phase retardation films with layered structures shown are samples 3-1 to 3-13. A tilted film with a frontal phase retardation Re(0) of 23 nm was formed by tilted evaporation on one side of a glass substrate with antireflective films on both sides, overlapping and layering. An antireflective film was then formed on the surface of the second tilted film. Ta₂O₅ was used as the material for the tilted film. By changing the substrate setting angle ω to change the evaporation angle, phase retardation film samples 3-1 to 3-13 with different Re(30) ratios were fabricated. The tilted films stacked in a single sample have the same Re(30) ratio.

[0231] For samples 3-1 to 3-13, contrast and black level uniformity were evaluated and scored using the same method as in Experiment 1. The results are shown in Table 4.

[0232] [Table 4]

[0233] sample Re(30) ratio Contrast Uneven black display Overall score 3-1 1 D B 5 3-2 1.2 D B 5 3-3 1.4 C B 8 3-4 1.5 B B 10 3-5 1.6 B B 10 3-6 2 B B 10 3-7 2.3 B B 10 3-8 2.5 B C 8 3-9 3 C C 6 3-10 3.5 C C 6 3-11 4 C C 6 3-12 4.5 D D 0 3-13 5 D D 0

[0234] The samples 3-2 to 3-11 shown in Table 4, with Re(30) values ​​of 1.2 to 4, correspond to embodiments of the phase difference film of the present invention. Compared to samples with Re(30) values ​​exceeding 4, the samples of these embodiments achieved higher overall scores. Furthermore, the samples with Re(30) values ​​of 1.4 to 4 achieved higher contrast compared to samples with Re(30) values ​​exceeding 4. Among the samples with Re(30) values ​​of 1.4 to 2.5, an even higher overall evaluation was achieved, and among the samples with Re(30) values ​​of 1.5 to 2.3, an improved contrast effect and a better effect in terms of uniform black display were obtained.

[0235] [Experimental Example 4]

[0236] Made Figure 29 The phase retardation sheets with layered structures shown are samples 4-1 to 4-13. Similar to the sample in Example 3, but with a 15 nm silicon oxide film formed between the tilted films. By changing the substrate setting angle ω to change the deposition angle of the tilted films, phase retardation sheets with different Re(30) ratios were fabricated, namely samples 4-1 to 4-13. The tilted films stacked in a single sample have the same Re(30) ratio.

[0237] For samples 4-1 to 4-13, contrast and black level uniformity were evaluated and scored using the same method as in Experiment 1. The results are shown in Table 5.

[0238] [Table 5]

[0239] sample Re(30) ratio Contrast Uneven black display Overall score 4-1 1 D A 7 4-2 1.2 D A 7 4-3 1.4 C A 10 4-4 1.5 B A 12 4-5 1.6 B A 12 4-6 2 B A 12 4-7 2.3 B A 12 4-8 2.5 B A 12 4-9 3 C A 10 4-10 3.5 C B 8 4-11 4 C B 8 4-12 4.5 D D 0 4-13 5 D D 0

[0240] The samples 4-2 to 4-11 shown in Table 5, with Re(30) values ​​of 1.2 to 4, correspond to embodiments of the phase difference film of the present invention. Compared with samples with Re(30) values ​​exceeding 4, the samples of the embodiments achieved higher overall scores. Furthermore, even higher overall scores were obtained in the samples with Re(30) values ​​of 1.4 to 3. Moreover, in the samples with Re(30) values ​​of 1.5 to 2.5, improved contrast and better performance in terms of uniform black display were achieved.

[0241] Here, we will give an example 5 to illustrate the effect of the difference between the phase difference IRe(15)ηa+45 and the phase difference IRe(15)ηa-45 at the ηa+45° azimuth centered on the azimuth ε where the phase difference IRe(15) is the largest, within ±6nm.

[0242] [Experimental Example 5]

[0243] In a phase difference plate composed of two tilted films with Re(0) = 32nm, the cross angle of the slow axis of the two tilted films was changed to produce samples with ΔRe(15)ηa ranging from 1nm to 7nm.

[0244] Furthermore, in a phase retardation plate consisting of three tilted films with Re(0) = 21 nm, Re(0) = 14 nm, and Re(0) = 17 nm respectively, samples with ΔRe(15)ηa ranging from 1 nm to 7 nm were fabricated by changing the cross angle of the slow axis of the three tilted films.

[0245] For each sample, the contrast was measured in the same manner as in Example 1. The contrast without a phase retarder was used as the baseline contrast, and the contrast of each sample was evaluated as follows.

[0246] A: More than 3 times the baseline contrast.

[0247] B: More than twice but less than three times the baseline contrast.

[0248] C: 1.5 times to less than 2 times the baseline contrast ratio

[0249] D: Less than 1.5 times the reference contrast ratio

[0250] The evaluation results are shown in Table 6.

[0251] [Table 6]

[0252]

[0253] As shown in Table 6, in both the case of two-layer tilted films and the case of three-layer films, ΔRe(15)ηa was below 6 nm, resulting in a contrast improvement rate of more than 1.5 times. In addition, when ΔRe(15)ηa was 1 nm to 5 nm, the contrast improvement rate was more than 2 times, and when ΔRe(15)ηa was 3 nm to 4 nm, a contrast improvement rate of more than 3 times was obtained.

[0254] "Phase difference plate of the third embodiment"

[0255] The above describes a phase retardation sheet consisting of one or more layers of tilted films. However, a phase retardation sheet may include not only tilted films but also a C-plate. As a phase retardation sheet of the third embodiment, an example of a phase retardation sheet 37 having a C-plate will be described.

[0256] like Figure 34As shown, the phase retardation plate 37 of this embodiment includes a substrate 23, a C-plate 50, tilted films 25a and 25b, and antireflective films 48 and 49. The C-plate 50 includes a first portion C-plate 50a and a second portion C-plate 50b disposed on both sides of the substrate 23. The first tilted film 25a is disposed on the first portion C-plate 50a, and the antireflective film 48 is disposed on the first tilted film 25a. Furthermore, the second tilted film 25b is disposed on the second portion C-plate 50b, and the antireflective film 49 is disposed on the second tilted film 25b.

[0257] like Figure 35 As shown, plate C 50 is composed of a multilayer film consisting of alternating layers of a high refractive index layer 51 with a relatively high refractive index and a low refractive index layer 52 with a relatively low refractive index. Plate C 50 has refractive index anisotropy, which does not show a phase difference for light incident perpendicularly in-plane, i.e., light incident at an incident angle of 0°, but produces a phase difference for light incident at an angle other than 0°.

[0258] exist Figure 35 The phase difference characteristics are shown relative to light incident on plate C50 at incident angles of 0°, 10°, and 15°. For example... Figure 36 As shown, the phase difference Re(0) relative to light incident at an angle of 0° is 0 nm. The phase difference Re increases with the angle of incidence. On the other hand, the phase difference Re(θ) is not azimuth-dependent and remains constant within an azimuth range of 0 to 360°. Furthermore, the value of the phase difference Re(15) is determined by the refractive index difference between the high-refractive-index layer and the low-refractive-index layer constituting the C-plate and the number of layers. The haze of the C-plate is preferably 0.4% or less. Since it is used in overlap with the tilted film, the haze of the phase retardation plate becomes the cumulative value of the haze of the tilted film and the haze of the C-plate. By setting the haze of the C-plate to 0.4% or less, the haze of the phase retardation plate can be suppressed. When used as a phase retardation compensation plate for liquid crystal display elements, the contrast can be improved and the unevenness of black display can be suppressed.

[0259] Furthermore, the haze of the phase retardation film 37 is preferably 1% or less. By stacking a C-plate on top of the multilayer tilted film 25, the overall haze increases, but if the haze of the phase retardation film 37 is suppressed to 1% or less, the effect of improving contrast and suppressing uneven black display can be sufficiently obtained.

[0260] As already explained, in the retardation plate 31, which has two tilted films 25a and 25b, the slow axis S2 is aligned with the fast axis F of the liquid crystal layer 17. Since their phases are opposite, the retardation plate 31 can compensate for the phase difference generated in the liquid crystal layer 17. Furthermore, if the absolute values ​​of the phase difference in the fast axis orientation of the liquid crystal layer 17 and the phase difference in the slow axis orientation of the retardation plate 31 are the same, the phase difference in the fast axis orientation of the liquid crystal layer can be well compensated. Specifically, when the pre-tilt orientation of the liquid crystal layer 17 is at 45°, the phase difference in the 45° orientation of the liquid crystal layer 17 is opposite to the phase difference in the 45° orientation of the retardation plate 31, and if the absolute values ​​of the phase differences are the same, the phase difference in the 45° orientation can be compensated even better.

[0261] On the other hand, it has been explained that in order to compensate for the frontal phase difference, the two tilted films 25a and 25b are preferably arranged with their slow axes S21 and S22 slightly offset from each other orthogonally. By offsetting their slow axes S21 and S22 from each other orthogonally, the azimuth symmetry of the phase difference of the phase difference of the phase difference plate 31, which is oriented at the 45° azimuth, is deviated. Therefore, when the phase value of the phase difference Re(15) caused by the pre-tilted component of the liquid crystal layer 17 is made to match the Re(15) of the phase difference plate 31 at the 45° azimuth, it is possible to generate an over-compensated azimuth in other azimuths.

[0262] Therefore, when the phase difference at the 15° incident angle and 45° orientation of the liquid crystal layer is set as A, and the phase difference at the 15° incident angle and 45° orientation of the phase difference plate 31 is set as B, and A < B, it is preferable to use the phase difference C (= BA) of the C plate to compensate for the difference BA.

[0263] To satisfy C=BA, increasing A requires decreasing C, and decreasing A requires increasing C. The phase difference A of the synthesized slow axis orientation when stacking tilted films depends on the Re(30) ratio of the tilted films and increases with the increase of the Re(30) ratio. As mentioned above, when the Re(30) ratio of the tilted films increases, there is a tendency for increased haze. The phase difference of the C plate depends on its film thickness. To increase the phase difference, it is necessary to increase the number of layers of multilayer films and increase the overall film thickness. The C plate tends to increase haze when the film thickness increases, and the manufacturing cost increases, while the manufacturing applicability decreases. Here, by setting the Re(30) ratio to 1.1 to 4.0 and combining it with the C plate, it is possible to balance the haze suppression effect with the manufacturing applicability of the C plate.

[0264] Additionally, with a C-board 50 available, it is possible to... Figure 34 The first portion C plate 50a is provided on one side of the substrate 23, and the second portion C plate 50b is provided on the other side, as in the case of the phase difference plate 37. Figure 37As shown, a C-plate 50 is formed on one side of the substrate 23. Furthermore, the C-plate 50 preferably has an anti-reflective function. The anti-reflective function can be assembled in the multilayer films constituting the first part C-plate 50a, the second part C-plate 50b, and the respective C-plate 50. Since it is not necessary to separately provide anti-reflective films between the substrate 23 and the C-plate 50, or between the C-plate 50 and the tilted film 25, the phase retardation plate 37 can be made thinner.

[0265] like Figure 34 As shown, in the phase retardation plate 37, in the case where the C plate 50 is formed separately on both sides of the substrate 23 (hereinafter referred to as the two-sided type) and as... Figure 37 The relationship between haze and the phase difference Re(30) of the C-plate was investigated in the case where the C-plate is formed on one side of the substrate 23 (hereinafter referred to as the single-sided type). Samples were fabricated with a layer structure where Re(30) is 0-35 nm for both the two-sided and single-sided C-plates. The C-plate was constructed as an alternating multilayer film with Nb2O5 layer as the high refractive index layer and SiO2 layer as the low refractive index layer. For both the two-sided and single-sided types, the anti-reflective function is achieved by adjusting the film thickness of each layer in the multilayer film constituting the C-plate and the overall layer structure.

[0266] The results of haze measurements for each sample are shown below. Figure 38 .

[0267] like Figure 38 As shown, in any Re(30), the two-sided type can suppress haze to a low level. That is, from the viewpoint of haze suppression, when the phase difference plate has a C-plate, it is preferable to form the C-plate separately on both sides of the substrate.

[0268] The layer structure of the C-plate fabricated in this example, with Re(30) = 26 nm and including anti-reflective function, is shown in Tables 7 and 8. In Tables 7 and 8, Nb represents niobium oxide (Nb2O5), and Si represents silicon oxide (SiO2).

[0269] Table 7 shows the layer structure of the two-sided C-plate. To obtain Re(30) = 26 nm, 39 layers of multilayer film with a total thickness of 931 nm, as shown in Table 7, were stacked on both sides of the substrate. Additionally, as... Figure 38 As shown, the haze of the bifacial C-plate with a total of two layers of multilayer film (Table 7) is 0.2%.

[0270] [Table 7]

[0271]

[0272] Table 8 shows the layer structure of a single-sided C-plate. To obtain Re(30) = 26 nm, a multilayer film of 82 layers with a total thickness of 1743 nm, as shown in Table 8, was stacked on one side of the substrate. Additionally, as... Figure 38As shown, the haze of the single-sided C-plate with the multilayer film in Table 8 is 0.35%.

[0273] [Table 8]

[0274]

[0275] Here, we present Experiment 6 to illustrate the function of the phase difference plate 37.

[0276] [Experimental Example 6]

[0277] Two tilted films with a frontal phase difference Re(0) of 23 nm were stacked with their slow axes intersecting at a 93° angle. They were formed on a glass substrate by tilted vapor deposition. Ta₂O₅ was used as the material for the tilted films. Based on the results of Experimental Example 1, samples with Re(30) ratios of 1 to 5 were fabricated by changing the substrate setting angle ω. Furthermore, as the C plate, based on the relationship between the phase difference Re(15) of the combined slow axis orientation of the tilted films in each sample (A) and the phase difference Re(15) of the C plate (C), and the phase difference B of the Re(15) of the pre-tilted orientation of the liquid crystal layer (A+C=B), C was set according to B. Samples 6-1 to 6-13 were fabricated in this manner.

[0278] For samples 6-1 to 6-13, contrast and black level uniformity were evaluated using the same method as in Test Example 1. Furthermore, the manufacturing suitability of the C-board was also evaluated in this example. The manufacturing suitability of the C-board was evaluated as follows.

[0279] A: No more than 90 layers and a reflectivity of less than 0.3%.

[0280] B: 91 to 110 floors with a reflectivity below 0.3%; or 80 to 110 floors with a reflectivity below 0.5% but exceeding 0.3%.

[0281] C: 111 to 130 layers with a reflectivity of less than 0.3%, or 79 to 130 layers with a reflectivity exceeding 0.5%.

[0282] D: 131 or more layers and reflectivity below 0.3%

[0283] The evaluation results for the manufacturing suitability of the C-board were also scored in the same way as for contrast and black level uniformity, and a comprehensive score was calculated for contrast, black level uniformity, and the manufacturing suitability of the C-board. The results are shown in Table 9.

[0284] [Table 9]

[0285]

[0286] The samples 6-2 to 6-11 shown in Table 9 correspond to embodiments of the phase difference film of the present invention. Compared with the samples with Re(30) exceeding 4, the samples with Re(30) of 1.2 to 4 in the embodiments have a higher contrast rating, achieving a significant improvement in high contrast. Furthermore, in the samples with Re(30) of 1.5 to 2.5, very high contrast and black display non-uniformity suppression are achieved, and the C-plate manufacturing applicability is excellent.

[0287] A phase difference of less than 3nm on the front side shows good results.

[0288] Here, we will take Experiment 7 as an example to illustrate the effect of the difference ΔRe(0) between the front and back phases of the two tilted films being less than ±3nm in a phase difference film with two tilted films.

[0289] [Experimental Example 7]

[0290] One of the tilted films was set to Re(0) = 32nm and Re(30) ratio = 2.0, and the Re(0) of the other tilted film was varied in the range of -28nm to 36nm. A phase difference plate with two tilted films was fabricated with a frontal phase difference ΔRe(0) of -4nm to +4nm.

[0291] Furthermore, a sample with a C-plate disposed on a combination of the same tilted membranes as described above was fabricated.

[0292] Contrast was measured in the same manner as in Test Example 1, and evaluated using the same criteria as in Test Example 1. The evaluation results are shown in Table 10.

[0293] [Table 10]

[0294]

[0295] As shown in Table 6, regardless of the presence or absence of a C-plate, setting the frontal phase difference between the two tilted films to ±3 nm results in improved contrast compared to cases exceeding ±3 nm. In samples without a C-plate, further contrast enhancement is achieved within a ΔRe(0) range of ±1 nm. Furthermore, in samples with a C-plate, further contrast enhancement is achieved within a ΔRe(0) range of ±2 nm, and even further enhancement is achieved within a ΔRe(0) range of ±1 nm.

[0296] Furthermore, as described above, for a phase difference plate 31 formed by stacking two or more inclined films 25 that satisfy the above-described conditional formulas (1) and (2), the absolute value of the difference between the first phase difference Re(15)ηa+45 of the incident light when the azimuth angle is +45° relative to the reference azimuth angle ηa and the second phase difference Re(15)ηa-45 of the incident light when the azimuth angle is -45° relative to the reference azimuth angle ηa is 6 nm or less.

[0297] However, even for phase retardation films formed from tilted films that do not satisfy conditions (1) and (2), for phase retardation sheets formed by stacking two or more phase retardation films, the absolute value of the difference between the first phase difference Re(15)ηa+45 of the incident light when the azimuth angle is +45° relative to the reference azimuth angle ηa and the second phase difference Re(15)ηa-45 of the incident light when the azimuth angle is -45° relative to the reference azimuth angle ηa is 6 nm or less. Such a phase retardation sheet can compensate for the phase difference generated in the liquid crystal layer with high precision by aligning the reference azimuth with the pre-tilted azimuth of the liquid crystal layer.

[0298] As described above, the phase difference plates 21, 31, 32, 35, 36, and 27 of the described embodiments can be used as phase difference compensation elements 20 for liquid crystal display elements 10. Hereinafter, a liquid crystal projector 110 equipped with a liquid crystal display element will be described.

[0299] LCD projector

[0300] like Figure 39 As shown, the liquid crystal projector 110 of the present invention includes a projection lens 116, a projector drive unit 117, and a display optical system 118.

[0301] Furthermore, the projector 110 has a zoom dial 121, a focus dial 122, and a light intensity adjustment dial 123 on the upper surface of the housing 119. In addition, a connection terminal (not shown) for connecting to external devices such as a computer is provided on the back of the housing 119.

[0302] Projection lens 116 amplifies the projection light incident from display optics system 118 and projects it onto screen 124 (reference). Figure 40 The projection lens 116 is composed of, for example, a zoom lens, a focusing lens, and an aperture. The zoom lens and the focusing lens are movably positioned along the projection optical axis L11. The zoom lens moves according to the operation of the zoom dial 121 and adjusts the magnification of the projected image. Furthermore, the focusing lens moves according to the movement of the zoom lens or the operation of the focusing dial 122 and adjusts the focus of the projected image. Moreover, the aperture adjusts the brightness of the projected image by changing the area of ​​the aperture opening according to the operation of the light amount adjustment dial 123.

[0303] The projector drive unit 117 controls the electrical operation of each part of the projector 110. For example, the projector drive unit 117 receives image data from a computer or the like connected to the projector 110 and displays it on the liquid crystal display element described later.

[0304] Furthermore, the projector drive unit 117 is equipped with motors that drive each part of the projection lens 116, and drives these motors according to the operation of the zoom dial 121, focus dial 122, light intensity adjustment dial 123, etc.

[0305] The display optical system 118 decomposes the light emitted from the light source into red light, green light, and blue light, which are then transmitted to the liquid crystal display elements 10A, 10B, and 10C (reference) that display information of each color, respectively. Figure 2 This generates various colored information lights. These information lights are then combined and used as projection light, which is projected onto the screen 124 via the projection lens 116.

[0306] like Figure 40 As shown, the display optical system 118 is composed of a light source unit 131, an information light generating unit 132 that generates information light from the light source unit 131, etc.

[0307] The light source unit 131 consists of a lamp 133, a reflector 134, an ultraviolet cut-off filter 136, an integrator 137, a polarizer 138, a relay lens 141, a collimating lens 142, etc.

[0308] Lamp 133 is a high-brightness light source, such as a xenon lamp, that emits natural white light without a specific polarization direction. The white light emitted from lamp 133 passes through ultraviolet cutoff filter 136 and enters integrator 137.

[0309] The ultraviolet cutoff filter 136 prevents the white light emitted by the lamp 133 from causing degradation such as browning in various filters (not shown) made of organic polymers or the like by removing ultraviolet light from the white light emitted by the lamp 133.

[0310] The reflector 134 is, for example, an elliptical surface mirror, with a lamp 133 positioned near one focal point of the elliptical surface. Furthermore, one end of an integrator 137 is positioned near the other focal point. Thus, white light emitted from the lamp 133 is efficiently guided to the integrator 137.

[0311] The integrator 137, for example, is composed of a glass rod and a microlens array disposed on the end face of the glass rod. It focuses the white light emitted from the lamp 133 and guides it to the collimating lens 142 via the relay lens 141. The amount of light incident from the lamp 133 onto the integrator 137 decreases further away from the light source optical axis L12, resulting in a non-uniform distribution centered on the light source optical axis L12. Therefore, the integrator 137 makes the light with such a non-uniform light distribution approximately uniform within a defined range centered on the light source optical axis L12. As a result, the projected image achieves approximately uniform brightness across the entire surface of the screen 124.

[0312] Collimating lens 142 adjusts the light emitted from integrator 137 into light parallel to the optical axis L12 of the light source. Polarizer 138 converts the unpolarized light incident from collimating lens 142 into linearly polarized light with a polarization component (hereinafter, S-polarization component) perpendicular to the plane of the paper. Furthermore, the S-polarization component light is guided to information light generation unit 132 via mirror 143a.

[0313] The information light generation unit 132 is composed of dichroic mirrors 146 and 147, liquid crystal display elements 10A, 10B and 10C, phase difference compensation elements 20A, 20B and 20C, and dichroic prism 61.

[0314] The dichroic mirror 146 is configured such that the angle between the normal direction of its surface and the optical axis of the incident light is 45°. Furthermore, the dichroic mirror 146 transmits the red light component of the S-polarized white light incident from the light source 131 and guides it to the reflector 143b. The reflector 143b reflects the red light transmitted through the dichroic mirror 146 toward the liquid crystal display element 10A.

[0315] Furthermore, the dichroic mirror 146 reflects the green and blue light components of the S-polarized white light incident from the light source 131 toward the dichroic mirror 147. The dichroic mirror 147 is configured such that the angle between the normal direction of its surface and the optical axis of the incident light is 45 degrees. The dichroic mirror 147 also reflects the green light component of the S-polarized light incident from the dichroic mirror 146 toward the liquid crystal display element 10B.

[0316] On the other hand, the dichroic mirror 147 transmits the blue light component of the S-polarized light incident from the dichroic mirror 146 and guides it to the reflector 143c. The blue light component is reflected by the reflectors 143c and 143d and incident on the liquid crystal display element 10C.

[0317] Liquid crystal display element 10A is Figure 1 The liquid crystal display element 10 is shown. The liquid crystal display element 10A is driven by the projector drive unit 117 and displays the red component of the projected image data received from a computer or the like in grayscale. By transmitting through this liquid crystal display element 10A, red light becomes red information light carrying the information of the red component of the projected image.

[0318] Similarly, the liquid crystal display element 10B is Figure 1 The liquid crystal display element 10 shown displays the green component of a projected image received from a computer or the like in grayscale. By transmitting the liquid crystal display element 10B, green light becomes green information light containing the green component of the projected image.

[0319] And similarly, the liquid crystal display element 10C is Figure 1 The liquid crystal display element 10 shown displays the blue component of the projected image data received from a computer or the like in grayscale. By transmitting the liquid crystal display element 10, blue light becomes blue information light containing the blue component of the projected image.

[0320] The phase difference compensation element 20A compensates for the phase difference of the red information light incident from the liquid crystal display element 10A to the dichroic prism 160. That is, the phase difference compensation element 20A compensates for the phase difference caused by the pre-tilt of the liquid crystal molecules.

[0321] Similarly, phase difference compensation element 20B compensates for the phase difference of green information light incident from liquid crystal display element 10B to dichroic prism 160, and phase difference compensation element 20C compensates for the phase difference of blue information light incident from liquid crystal display element 10C to dichroic prism 160.

[0322] The dichroic prism 160 is made of a transparent material such as glass and is roughly cubic in shape, with mutually orthogonal dichroic faces 162 and 163 inside. Dichroic face 162 reflects red light and allows green light to pass through. On the other hand, dichroic face 163 reflects blue light and allows green light to pass through.

[0323] Therefore, the dichroic prism 160 combines the red, green, and blue information light incident from the liquid crystal display elements 151, 152, and 153 respectively into projection light, guides it to the projection lens 116, and displays the projected image in full color on the screen 124.

[0324] In the liquid crystal projector 110, phase difference compensation elements 20A, 20B, and 20C are used, such as the phase difference elements 31, 32, 33, 36, or 37 described above, thereby efficiently compensating for the phase difference caused by the pre-tilt of the liquid crystal molecules. As a result, a projected image with improved contrast and suppressed black display unevenness can be obtained.

[0325] The entire contents of the disclosure of Japanese Patent Application No. 2020-113612, filed on June 30, 2020, are incorporated herein by reference.

[0326] All documents, patent applications and technical standards described in this specification are incorporated herein by reference to the same extent as those specifically and individually described herein.

Claims

1. A retardation film comprising a substrate and a retardation film formed on at least one side of the substrate, the retardation film being an inclined film having a columnar structure inclined relative to the normal of the film forming surface on which the retardation film is formed, and exhibiting refractive index anisotropy as an optical property, wherein, Let the three principal refractive indices of the biaxial refractive index ellipsoid exhibiting the refractive index anisotropy be nx, ny, and nz. Let the principal refractive index of the columnar structure in the length direction (X-axis) be nx, the principal refractive index of the ellipse perpendicular to the X-axis in the major axis direction (Y-axis) be ny, and the principal refractive index of the minor axis direction (Z-axis) be nz. Then the following condition (1) is satisfied. Furthermore, if the incident angle in the direction inclined towards the X-axis with the normal as the reference is positive, the phase difference of the incident light at an incident angle of +30° is Re(+30), the phase difference of the incident light at an incident angle of -30° is Re(-30), and the ratio of Re(+30) to Re(-30), i.e. the phase difference ratio, is Re(30), then the following condition (2) is satisfied. ny>nx>nz (1) Re(30) ratio=Re(30) / Re(-30)=1.1~4.0 (2).

2. The phase difference plate according to claim 1, wherein, If we define the Y-axis corresponding to the largest principal refractive index ny among the three principal refractive indices as the slow axis, and the YS-axis corresponding to the principal refractive index ny and having the longest phase delay of the incident light as the slow axis, and the axis onto the film forming surface as the ZS-axis, then the slow axis is orthogonal to the ZS-axis.

3. The phase difference plate according to claim 1 or 2, wherein, The Re(30) ratio satisfies the following condition (2-1). Re(30) ratio=Re(30) / Re(-30)=1.2~4.0 (2-1).

4. The phase difference plate according to claim 1 or 2, wherein, The Re(30) ratio satisfies the following condition (2-2). Re(30) ratio=Re(30) / Re(-30)=1.4~3.0 (2-2).

5. The phase difference plate according to claim 1 or 2, wherein, The Re(30) ratio satisfies the following condition (2-3). Re(30) ratio=Re(30) / Re(-30)=1.5~2.5 (2-3).

6. The phase difference plate according to claim 1 or 2, wherein, The tilted film is composed of an oxide containing at least one of Si, Nb, Zr, Ti, La, Al, Hf and Ta.

7. The phase difference plate according to claim 1 or 2, wherein, The phase difference film is stacked in two or more layers.

8. The phase difference plate according to claim 7, wherein, Let the slow axis be defined as the YS axis obtained by projecting the Y-axis corresponding to the largest principal refractive index ny among the three principal refractive indices onto a plane parallel to the film formation surface, and the YS axis corresponding to the principal refractive index ny with the longest phase retardation of the incident light, and let the orientation of the slow axis when the substrate is rotated about the normal be the azimuth angle of the substrate. The reference azimuth angle is defined as the azimuth angle from 0° to 360° where the phase difference of the incident light relative to the incident angle of +15° with respect to the normal is the largest. The absolute value of the difference between the first phase difference of the incident light when the azimuth angle is +45° with respect to the reference azimuth angle and the second phase difference of the incident light when the azimuth angle is -45° with respect to the reference azimuth angle is less than 6 nm.

9. The phase difference plate according to claim 7, wherein, The phase difference between the front and back sides is 0.1nm to 5nm.

10. The phase difference plate according to claim 7, wherein, A haze value indicating the degree of scattered light generation is below 0.3%.

11. The phase difference plate according to claim 7, wherein, The phase difference film is formed on both sides of the substrate.

12. The phase difference plate according to claim 7, wherein, Two or more of the phase retardation films are stacked on one side of the substrate. Furthermore, an intermediate layer is provided between adjacent phase retardation films.

13. The phase difference plate according to claim 7, wherein, The substrate comprises a plurality of substrates having at least one layer of the phase retardation film formed thereon.

14. The phase difference plate according to claim 7, wherein, The two phase retardation films are stacked, and their respective slow axes are staggered at an angle within 90°±3°.

15. The phase difference plate according to claim 7, wherein, The film has two phase retardation layers stacked on top of each other, and the difference in the phase difference between their front sides is less than ±3nm.

16. The phase difference plate according to claim 7, wherein, It also has a C-plate with a haze value of 0.4% or less, which indicates the degree of scattered light generation.

17. The phase difference plate according to claim 16, wherein, The C-plate has anti-reflective properties.

18. The phase difference plate according to claim 16, wherein, A haze value of less than 1% indicates the degree of scattered light generation.

19. A liquid crystal projector, comprising: Liquid crystal layer; and A phase difference compensation element that compensates for the phase difference generated in the liquid crystal layer. As the phase difference compensation element, it comprises a phase difference plate as described in any one of claims 1 to 18.

20. A method for adjusting the contrast of a liquid crystal display element, the liquid crystal display element comprising a liquid crystal layer and a phase difference compensation element for compensating for a phase difference generated in the liquid crystal layer, wherein in the contrast adjustment method, The phase difference compensation element is the phase difference plate according to claim 13. The contrast of the liquid crystal display element is adjusted by rotating at least one of the plurality of substrates having at least one layer of the phase retardation film about an axis perpendicular to the film formation surface relative to the other substrates.

Images