JP2006171328A - Phase difference compensation element, optical modulation system, liquid crystal display device, and liquid crystal projector - Google Patents

Phase difference compensation element, optical modulation system, liquid crystal display device, and liquid crystal projector Download PDF

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JP2006171328A
JP2006171328A JP2004363306A JP2004363306A JP2006171328A JP 2006171328 A JP2006171328 A JP 2006171328A JP 2004363306 A JP2004363306 A JP 2004363306A JP 2004363306 A JP2004363306 A JP 2004363306A JP 2006171328 A JP2006171328 A JP 2006171328A
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liquid crystal
phase difference
light
compensation layer
retardation
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Takamitsu Fujii
Kenichi Nakagawa
謙一 中川
隆満 藤井
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Fuji Photo Film Co Ltd
富士写真フイルム株式会社
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Priority claimed from EP05820248A external-priority patent/EP1825305A4/en
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Abstract

A light blocking characteristic and a viewing angle characteristic are improved by a pair of polarizing elements arranged in crossed Nicols.
A transparent glass substrate 10 is provided with a first retardation compensation layer 12 and a second retardation compensation layer 14 each made of an inorganic material. The first retardation compensation layer 12 is formed by laminating two kinds of high and low vapor deposition films that are sufficiently thin with respect to the wavelength, and has a negative C-plate. The second retardation compensation layer 14 is composed of at least a two-layered oblique vapor deposition film and becomes a positive O-plate. The first phase compensation layer compensates the phase difference for the light beam incident obliquely with respect to the optical axis, and the second phase compensation layer matches the polarization direction of the linearly polarized light that has passed through the polarizer with the transmission axis of the analyzer. Rotate in the direction not to suppress the leakage light from the analyzer and improve its light blocking characteristics.
[Selection] Figure 2

Description

  The present invention relates to a phase difference compensation element that is used by being disposed between a pair of polarizing elements that are arranged in crossed Nicols, and more specifically, a phase difference compensation element that has improved viewing angle dependency, and a light modulation system and liquid crystal using the same. The present invention relates to a projector.

The following background art is known for the present invention.
Claire Gu & Pochi Yeh "Extended Jones matrix method. II" Journal of Optical Society of America A / Vol. 10 No.5 / May 1993 p966−973

  A polarizing plate is used as a polarizing element in a liquid crystal cell that performs light modulation utilizing the optical rotation and birefringence of liquid crystal molecules. In a transmissive liquid crystal cell, polarizing plates are arranged perpendicular to the optical axis on the light incident surface side and the light emitting surface side, respectively, and the polarizing plate on the light incident surface side converts non-polarized light into linearly polarized light into the liquid crystal cell. The polarizer to be incident and the polarizing plate on the light exit surface side function as an analyzer that blocks or transmits the modulated light from the liquid crystal cell according to the direction of polarization. As a polarizing element used for such a purpose, a wire grid polarizing element is known in addition to a polarizing plate, but generally a polarizing plate is frequently used. A polarizing plate generally has a structure in which a PVA (polyvinyl alcohol) film adsorbed with iodine or a dye is uniaxially stretched and oriented, and its front and back are covered with a protective layer, and the transmission axis and absorption perpendicular to each other in a plane perpendicular to the optical axis. And a shaft. When non-polarized light is incident on this polarizing plate, it is decomposed into mutually orthogonal polarized components, the polarized component light parallel to the absorption axis is blocked, and the polarized component light parallel to the transmission axis is transmitted.

  When this polarizing plate is combined with, for example, a TN (Twisted Nematic) liquid crystal cell and used in a crossed Nicol arrangement in which the transmission axes are orthogonal to each other, a normally white mode liquid crystal display device is obtained. A TN liquid crystal cell is a cell in which rod-like liquid crystal molecules constituting a liquid crystal layer are filled between a pair of transparent substrates on which transparent electrodes and alignment films are formed, and is long in a normal state where no voltage is applied between the substrates. The orientation is maintained so that the axis is substantially parallel to the substrate, and the orientation of the major axis is slightly inclined for each liquid crystal molecule in the thickness direction, and the orientation is twisted by 90 ° as a whole.

  When linearly polarized light that has been transmitted through the polarizer is incident on the TN liquid crystal cell in this alignment state, the polarization direction is rotated by 90 ° following the alignment state of the liquid crystal molecules and emitted. Therefore, if the transmission axis of the analyzer is orthogonal to the transmission axis of the polarizer, the linearly polarized light is transmitted through the analyzer as it is to display a bright state. In addition, when a saturation voltage is applied between the electrodes of the TN liquid crystal cell, the twist of the liquid crystal molecules disappears, the major axis is aligned with the optical axis direction, and the linearly polarized light incident through the polarizer does not change the polarization direction. The light is emitted from the liquid crystal cell. Since the polarization direction of the emitted light coincides with the absorption axis of the analyzer and is blocked by the analyzer, a dark state is displayed.

  A pair of polarizing plates arranged in crossed Nicols is also used for a polarizing microscope or the like. If a sample such as a mineral is placed between the polarizing plates and the sample is optically isotropic when illuminated through the polarizing plate, the linearly polarized light incident through the polarizing plate is polarized. As it reaches the analyzer without changing, it is blocked and the observation field becomes dark. On the other hand, when the crystal structure having optical anisotropy is included in the sample, the incident linearly polarized light is modulated by the birefringence action, and the modulated light is observed through the analyzer. It becomes like this.

  When a pair of polarizing plates are used in a crossed Nicols arrangement for such a purpose, it is known that sufficient blocking characteristics cannot be obtained depending on the viewing angle when observing through an analyzer. When a pair of polarizing plates are arranged in crossed Nicols and incident light is incident from one polarizing plate, in principle, if the incident light is all a light bundle parallel to the optical axis, light is emitted from the other polarizing plate. Never do. However, since a general light source has a spatial expansion, the incident light includes not a few rays inclined with respect to the optical axis. For example, in devices such as liquid crystal projectors, metal halide lamps, ultra-high pressure mercury lamps, and the like are used together with reflectors, and the light from such a light source includes a lot of light bundles inclined with respect to the optical axis. With respect to such incident light, it is not possible to provide a sufficient light blocking function with only a pair of polarizing plates arranged in a crossed Nicol manner.

  FIG. 18 shows light blocking characteristics when light from a general light source is observed through a pair of polarizing plates arranged in crossed Nicols, and shows that the relative luminance values of light passing through the polarizing plate on the emission side are equal. Connected and graphed. The center of the graph corresponds to a viewing angle of 0 °, the angle represented by concentric circles represents the viewing angle, and the angle represented along the outer edge represents the azimuth angle of observation. From this graph, it can be seen that as the viewing angle increases, the relative luminance value increases, and when the viewing angle exceeds 60 °, 10% or more of light is leaked and observed. In addition, since the absorption axes of the pair of polarizing plates are orthogonal to each other at azimuth angles of 0 ° and 90 °, light is likely to leak at an azimuth angle of 45 ° with respect to the absorption axis. A 90 ° rotational symmetry is observed.

  In order to improve the light blocking characteristics, particularly the viewing angle characteristics, of a pair of polarizing plates arranged in crossed Nicols, it is known to arrange various phase difference compensation elements in the optical path. Non-Patent Document 1 discloses a phase difference compensation element that combines C-plate and A-plate, and in particular, a phase difference compensation element that combines a positive C-plate and a quarter-wave plate, It is described that a phase difference compensation element combining a C-plate and a three-quarter wavelength plate is effective in improving the viewing angle characteristics of a pair of polarizing plates arranged in crossed Nicols.

  As described in Non-Patent Document 1, a phase difference compensation element combining C-plate and A-plate is effective to improve the viewing angle characteristics of a polarizing plate arranged in a crossed Nicol arrangement. Such a retardation compensation element could not be produced unless a uniaxially stretched polymer film was used. Such an organic material has a problem in terms of temperature dependency and hygroscopicity, and has a drawback that its optical characteristics are easily changed depending on the use environment or long-time use. Although the viewing angle is improved, it is difficult to prevent about 10% of light leakage when the viewing angle exceeds 60 °. In principle, a phase difference compensator combining two biaxial retardation plates is also known, but a biaxial retardation plate can only be made of a polymer film, and the creation itself Is also very difficult.

  The present invention has been made based on the above background, and provides a phase difference compensation element that can further improve the light blocking function by a pair of polarizing plates arranged in a crossed Nicol configuration and can also improve the viewing angle dependency. It is another object of the present invention to provide a light modulation system and a liquid crystal projector that effectively use this phase difference compensation element. Furthermore, the retardation compensation element of the present invention can be easily made of an inorganic material because of its unique structure, and is extremely advantageous in terms of heat resistance and durability.

  The retardation compensation element of the present invention comprises a first retardation compensation layer and a second retardation compensation layer formed on a transparent substrate arranged perpendicular to an optical axis perpendicular to a pair of polarizing plates. And used between the polarizing elements. The first retardation compensation layer is formed so that an optical axis that is optically isotropic (corresponding to an incident direction of incident light in which the refractive index for ordinary light and extraordinary light is equal) is perpendicular to the transparent substrate, The other second retardation compensation layer is composed of a multilayer film of three or more layers having different optical axis directions, and the azimuths when at least two of the optical axes are orthogonally projected onto the transparent substrate are substantially opposite to each other. Formed as follows. Furthermore, each of the first and second retardation compensation layers used in the present invention can be made of an inorganic material, and the optical performance can be kept stable without being significantly affected by changes in the usage environment or aging. it can.

  The first and second retardation compensation layers are preferably manufactured efficiently by vapor deposition or sputtering deposited thin films. The first retardation compensation layer is composed of a vapor deposition film in which a high refractive index material and a low refractive index material are alternately laminated, and the optical film thickness of the two types of high and low vapor deposition films is more than 1/100 of the reference wavelength. One of the characteristics is that it is within a range of 1/5 or less, and is sufficiently thin as compared with a film thickness of a general optical thin film utilizing a so-called light interference action.

  The retardation compensation element of the present invention is arranged so that the orientation of the optical axis of any one of the multilayer films constituting the second retardation compensation layer coincides with the transmission axis of the polarizing element on the incident side. It is more effective to use. Moreover, it is also possible to provide an antireflection layer made of a vapor deposition film on at least one of the light incident surface side and the light output surface side of the phase difference compensating element of the present invention. When using the retardation compensator of the present invention in an optical modulation system including a liquid crystal cell, it is preferable to dispose the retardation compensator on the light incident surface side of the liquid crystal cell. It may be of type. When using a reflective liquid crystal cell, the modulated light from the liquid crystal cell may be incident on the projection lens off-axis and projected onto the screen.

  According to the phase difference compensation element of the present invention, the first phase difference compensation layer whose optical axis is perpendicular to the transparent substrate performs phase difference compensation for oblique incident light according to the incident angle. In addition, the second retardation compensation layer formed of a multilayer film in which each optical axis is oriented in various directions is a composite O− that rotates the polarization direction of linearly polarized light according to the inclination of incident light. It is considered that it functions as a plate, and the interaction of these retardation compensation layers can improve the viewing angle characteristics of a light modulation optical system including a pair of polarizing elements arranged in crossed Nicols. When at least two of the multilayer films constituting the second retardation compensation layer have a relationship in which the azimuths of the optical axes are substantially opposite to each other, the viewing angle characteristics are more effectively improved. Has been verified empirically. Here, the direction of the optical axis is substantially opposite means that the two optical axes of interest are arranged so that the direction of the two optical axes is approximately 180 °, preferably within 180 ° ± 5 °, and more The angle is preferably 180 ° ± 2 °, particularly preferably 180 °.

  Further, when the optical axis of any one of the multilayer films constituting the second retardation compensation layer or the optical axes of the two layers that are substantially opposed to each other are made coincident with the transmission axis, a good light blocking effect is obtained. can get. If each of the first and second retardation compensation layers is composed of an inorganic material, particularly a vapor deposition film, it is advantageous not only in heat resistance and durability but also in efficient production and excellent mass productivity.

  The phase difference compensation element of the present invention can be applied to various light modulation systems including a pair of polarizing elements arranged in a crossed Nicols state. Typically, a liquid crystal display device such as a direct-view type liquid crystal monitor, and further a liquid crystal cell The liquid crystal projector can be suitably used for a liquid crystal projector that displays a projected image and projects an image by performing light modulation. As a liquid crystal cell, not only a transmissive type but also a reflective type liquid crystal cell can be used if it is assumed to be used off-axis. As a projector, not only a front projection type but also a rear projection type can be used. It may be.

  As shown in FIG. 1, the phase difference compensation element 2 of the present invention is used by being disposed perpendicular to the optical axis 5 between a pair of polarizing plates 3, 4 disposed perpendicular to the optical axis 5. The polarizing plates 3 and 4 have a crossed Nicols arrangement in which the transmission axes are orthogonal to each other. If all of the incident light 7 is a parallel light beam parallel to the optical axis 5, the polarized light on the output side without the phase difference compensation element 2. Although no light is emitted from the plate 4, by using this phase retarder compensation element 2, even if the incident light 7 includes a light bundle tilted with respect to the optical axis 5, the light is emitted from the polarizing plate 4. The incident light 8 can be greatly reduced.

The phase difference compensation element 2 has a cross-sectional structure schematically shown in FIG. A first retardation compensation layer 12 and a second retardation compensation layer 14 are formed by vapor deposition on one surface of a glass substrate 10 serving as a support, and an antireflection layer by vapor deposition is formed on the uppermost layer and the back surface of the glass substrate 10. 15 and 16 are formed. Each of the antireflection layers 15 and 16 is for preventing surface reflection. For example, a single-layer film in which MgF 2 which is a low refractive index material is formed with an optical film thickness λ / 4, or a combination of different vapor deposition materials is used. An antireflection film can be used. The first and second retardation compensation films 12 and 14 and the antireflection films 15 and 16 made of vapor deposition films can be formed by sputtering film deposition as well as vacuum vapor deposition by resistance heating or electron beam heating. . In addition, the first retardation compensation layer 12 and the second retardation compensation layer 14 can perform the same operation even if this vertical relation is reversed, and are formed on either the front or back surface of the glass substrate 10. May be.

  As shown in FIG. 3, the first retardation compensation layer 12 is composed of a multilayer film in which two types of vapor deposition films L1 and L2 having different refractive indexes are alternately laminated on a glass substrate 10, and the respective vapor deposition directions are vapor deposition. Perpendicular to the surface. The optical film thickness (product of physical film thickness and refractive index) of each layer is sufficiently smaller than a standard light wavelength (for example, 550 nm), preferably λ / 100 to λ / 5, more preferably λ / 50 to λ / 5, in practice, λ / 30 to λ / 10 is appropriate, and is sufficiently thinner than an optical thin film using general optical interference. The multilayer film thus formed exhibits a negative C-plate action which is a uniaxial birefringent body, and its optical axis is perpendicular to the glass substrate 10 (parallel to the optical axis 5). The first retardation compensation layer 12 may be other than the multilayer film as long as it has a positive or negative C-plate effect.

  The design procedure of the first retardation compensation layer 12 is as follows. The birefringence Δn of the first retardation compensation layer 12 is an optical property of two kinds of vapor deposition films L1 and L2 having different refractive indexes as described in “Optical Vol. 27 No. 1 (1998) p.12-17”. It is determined by the ratio of the film thickness, and becomes larger as there is a difference in the respective refractive indexes. The retardation (retardation) obtained in the first retardation compensation layer 12 is given by the product “d1Δn1” of the birefringence Δn1 and the physical total film thickness d1 of the first retardation compensation layer 12. Therefore, in order to obtain a desired retardation, a film thickness ratio that increases the value of birefringence Δn1 obtained from these materials is obtained, and based on the birefringence Δn1, the entire first retardation compensation layer 12 is obtained. What is necessary is just to determine the total film thickness d1.

Actually, a thin film multi-layer deposition sample in which 40 layers of TiO 2 layers having a physical film thickness of 15 nm and SiO 2 layers having a physical film thickness of 15 nm are alternately laminated on the glass substrate 10 is prepared and measured using a spectroscopic ellipsometer. As a result, it is a negative birefringent body that gives a phase difference of 208 nm, and the incident direction of the light beam when it shows optical isotropy to the incident light beam, that is, the direction of the optical axis is It was confirmed to function as a negative C-plate consistent with the normal.

As a vapor deposition material for the vapor deposition films L1 and L2, as a high refractive material, TiO 2 (n = 2.about.2.4), ZrO 2 (n = 2.20), etc., as a low refractive index material, SiO 2 (n = 1.40 to 1.48), MgF 2 (n = 1.39), CaF 2 (n = 1.30), and the like, and various materials listed below are also used for the deposited films L1 and L2. It can be used as a vapor deposition material. The values in parentheses are approximate values of the refractive index. CeO 2 (2.45), Nb 2 O 5 (2.31), SnO 2 (2.30), Ta 2 O 5 (2.12), In 2 O 3 (2.00), ZrTiO 4 (2 .01), HfO 2 (1.91), Al 2 O 3 (1.59-1.70), MgO (1.7), ALF 3 , diamond thin film, LaTiO x , samarium oxide and the like. The combination of the high refractive index thin film layer material and the low refractive index thin film layer material is preferably TiO 2 / SiO 2, but Ta 2 O 5 / Al 2 O 3 , HfO 2 / SiO 2 , MgO / Examples thereof include MgF 2 , ZrTiO 4 / Al 2 O 3 , CeO 2 / CaF 2 , ZrO 2 / SiO 2 , ZrO 2 / Al 2 O 3 and the like.

  The first retardation compensation layer 12 may be formed by alternately depositing vapor deposition films L1 and L2 having two kinds of refractive indexes, high and low. Therefore, a shutter is provided so that each evaporation source can be shielded from the glass substrate 10, and the two types of vapor deposition films L1 and L2 are alternately laminated by alternately opening and closing these shutters, or The glass substrate 10 is held on a substrate holder that circulates and moves at a constant speed, and two kinds of vapor deposition films L1 and L2 are sequentially stacked by passing the substrate over each evaporation source in the process of circulating and moving the substrate. Can be used. Thereby, when a multilayer thin film is obtained, the vacuum chamber only needs to be evacuated once, so that efficient production becomes possible.

  As shown in FIG. 4, the second retardation compensation layer 14 has a four-layer structure in which four types of oblique deposition films S1, S2, S3, and S4 are laminated. As shown in FIG. 2, the first obliquely deposited film S1 is laminated on the first retardation compensation layer 12, but the first retardation compensation layer 12, the second retardation compensation layer 14, and the like. , The first layer of obliquely deposited films S1 is formed on the glass substrate 10, and the second, third and fourth layers of obliquely deposited films S2, S3 and S4 are sequentially stacked thereon. The first retardation compensation layer 12 is formed, or the first retardation compensation layer 12 and the second retardation compensation layer 14 are formed on the front and back of the glass substrate 10, and the antireflection layers 15 and 16 are formed on the uppermost layers, respectively. It is also possible to laminate.

  Unlike the vapor deposition films L1 and L2 constituting the first phase difference compensation layer 12, each of the oblique vapor deposition films S1 to S4 is vapor-deposited from an oblique direction with respect to the vapor deposition surface S0 and is directed to the vapor deposition direction for each layer. It has an aggregate structure of minute columnar elements M1 to M4 grown obliquely. Such an obliquely deposited film has a positive O-plate property that exhibits a structural birefringence even in a single layer, but is optical for light rays traveling parallel to the growth direction of the columnar elements M1 to M4. Isotropic. Therefore, the optical axis coincides with the growth direction of the columnar element after entering at the interface with a medium (for example, air) having a refractive index of 1 (for example, air), and is oblique from the growth direction of the columnar element. The direction is inclined by an angle corresponding to the refractive index of the deposited film. The direction of vapor deposition when forming the oblique vapor deposition films S1 to S4 is not perpendicular to the vapor deposition surface S0, and the growth direction of the columnar elements M1 to M4 is changed by changing the vapor deposition direction for each layer. Since the directions are changed, the azimuths when the optical axes of the respective layers are orthogonally projected onto the deposition surface S0 are different from each other.

  The oblique vapor deposition films S1 to S4 can be produced using, for example, the vapor deposition apparatus shown in FIG. In FIG. 5, a base holder 20 is provided with a material holder 21 that rotates in a turret manner, and vapor deposition materials 22 and 23 are accommodated therein. After the vacuum chamber 24 is evacuated, the vapor deposition material 22 is irradiated with the electron beam 27 from the electron gun 25 to evaporate the vapor deposition material 22, thereby performing vacuum vapor deposition. The start and stop of vacuum deposition can be controlled by opening and closing the shutter 29, and the deposition materials 22 and 23 can be selected and used by rotating the material holder 21. Basically, the second retardation compensation layer 14 is formed to be a multilayer film using one kind of vapor deposition material. By using such a material holder 21, different types of vapor deposition can be performed as necessary. It is also possible to use materials.

  A substrate holder 30 disposed obliquely above the material holder 21 is provided, and a transparent sample substrate 26 is held. The normal line of the support surface of the substrate holder 30 is inclined by an angle β with respect to the line segment P extending vertically from the vapor deposition material 22, and therefore the vapor deposition surface of the sample substrate 26 is also inclined by the angle β with respect to the line segment P. This angle β can be adjusted by rotating the substrate holder 30 about an axis perpendicular to the paper surface. Further, by rotating the substrate holder 30 around the axis 30a, the angle α corresponding to the azimuth angle of the line segment P in the vapor deposition surface can be adjusted. Since the line segment P corresponds to the vapor deposition direction with respect to the vapor deposition surface, the vapor deposition direction with respect to the vapor deposition surface can be adjusted in two ways as a result by changing the angles α and β. As described above, the angle α corresponds to the azimuth angle of the vapor deposition direction in the vapor deposition surface, and the angle β corresponds to the polar angle representing the inclination of the vapor deposition direction with respect to the vapor deposition surface. It is represented by α and polar angle β.

  Reference numeral 31 in the figure represents a crystal-type film thickness monitor, which monitors the film thickness of the vapor deposition film on the measurement surface, and the degree of vapor deposition proceeds on the sample substrate 26 held by the substrate holder 30. It is for measuring relatively whether or not. Reference numeral 32 denotes an ellipsometer, which receives the measurement light from the projector 33 through the monitor substrate 28 and measures the phase difference associated with birefringence while forming an obliquely deposited film on the sample substrate 26. Can do. The measurement surface of the film thickness monitoring monitor 31 and the birefringence Δn measurement system including the monitor substrate 28 can be rotated so as to coincide with the polar angle β of the substrate holder 30. Each time the formation of the oblique deposition film is completed, the phase difference can be monitored for each layer by exposing the new measurement surface and the monitor substrate surface due to the displacement of the mask plate. . The retardation of the obliquely deposited film can be estimated from the phase difference data measured by the ellipsometer 32. Therefore, if the deposition is performed while monitoring the measurement data obtained from the ellipsometer 32 and the film thickness monitoring monitor 31, each layer is desired. It is possible to obtain an obliquely deposited film having the following retardation.

  Through the above operation, the second retardation compensation layer made of the oblique vapor deposition film having a multilayer structure can be formed on the sample substrate 26 while monitoring the retardation for each layer. Further, as shown in FIG. 2, even after the first retardation compensation layer 12 is formed on the glass substrate 10, the glass substrate 10 is held by the substrate holder 30, and birefringence and film thickness set in advance for each layer The multilayer second retardation compensation layer 14 can be formed on the first retardation compensation layer 12 by performing oblique vapor deposition.

  As shown in FIG. 6, the vapor deposition direction P with respect to the vapor deposition surface S0 is measured from the azimuth angle α measured counterclockwise from the x axis and the z axis when orthogonally projected onto the xy coordinate plane on the vapor deposition surface S0. The polar angle β can be expressed as follows. The polar angle β is an angle that does not have positive and negative directivity as an inclination from the z axis, but the azimuth angle α has directivity with reference to the x axis. The direction of the x-axis is set so that δ = 45 ° with respect to the transmission axes 3a and 4a of the polarizing plates 3 and 4, and is common to the obliquely deposited films S1 to S4. As seen in FIG. 18, the viewing angle characteristics of the pair of polarizing plates 3 and 4 arranged in crossed Nicols have a rotational symmetry of about 90 °, so the direction of the x-axis is obliquely deposited films S1 to S4. As long as they are common, they may be arbitrary.

  The optical axes of the obliquely deposited films S1 to S4 substantially coincide with the deposition direction P of each deposited film. The obliquely deposited films S1 to S4 each have a positive O-plate property that exhibits a structural birefringence by itself, but are optical for light beams traveling parallel to the growth direction of the columnar elements M1 to M4. Isotropic. Accordingly, the respective optical axes of the obliquely deposited films S1 to S4 are defined by the growth direction of the columnar element M1 and the incident direction of the traveling light beam after being refracted and incident at the interface with a medium (for example, air) having a refractive index of 1. In agreement with the growth direction of the columnar elements M1 to M4, the inclination is strictly an angle corresponding to the refractive index of each obliquely deposited film. Strictly speaking, the direction is slightly shifted from the deposition direction P. Since the difference in effect is almost negligible, the direction of the optical axis can be approximated by the azimuth angle α and the polar angle β.

  When the second retardation compensation layer 14 is formed, the azimuth angle α and polar angle β can be arbitrarily determined for each of the obliquely deposited films S1 to S4 using the deposition apparatus shown in FIG. The refractive index of the vapor deposition material of the oblique vapor deposition films S1 to S4 is known, and the direction of the optical axis of the oblique vapor deposition films S1 to S4 can be regarded as substantially coincident with the respective vapor deposition directions. The optical axes of the side-deposited films S1 to S4 can be arbitrarily set as the direction of oblique deposition. Therefore, the present inventors prepared various samples while adjusting the azimuth angle α and polar angle β of each of the obliquely deposited films S1 to S4 when forming the second retardation compensation layer 14 having a four-layer structure. The viewing angle dependence was evaluated. As a result, in particular, the second retardation compensation layer 14 is composed of three or more oblique vapor deposition films, and the two optical layers projected on the vapor deposition surface have a 180 ° relationship with each other. It was confirmed that the viewing angle characteristics can sometimes be improved.

In addition to the azimuth angle α, there are various parameters for improving the viewing angle characteristics, such as the polar angle β value, the thickness of each obliquely deposited film, and the retardation value. Although it is very difficult to comprehensively verify the correlation with the above, it has been verified that examples described later exhibit practically excellent characteristics. Further, as the vapor deposition material of the oblique vapor deposition film of the second retardation compensation layer 14, as in the first retardation compensation layer 12, an oblique vapor deposition film such as TiO 2 , SiO 2 , ZrO 2 , Ta 2 O 3 is used. Various materials can be used as long as they have sufficient light transmission characteristics regardless of the wavelength.

Hereinafter, specific examples of the phase difference compensating element 6 using the present invention will be described. Corning 1737 (50 mm × 50 mm) was used as the glass substrate 10, washed with acetone and sufficiently dried, and then set in a vapor deposition apparatus for performing normal front vapor deposition (β = 0 °). The vacuum chamber was evacuated to 1 × 10 −4 Pa and the glass substrate was heated to 300 ° C. to form a three-layer antireflection film (corresponding to the antireflection layer 16 in FIG. 2). This antireflection film is formed by laminating SiO 2 with an optical film thickness of λ / 4, TiO 2 of λ / 2, and SiO 2 of λ / 4 sequentially from the glass substrate side, and the reference wavelength λ is 550 nm.

  After forming the antireflection layer, the glass substrate was turned upside down in the vacuum layer, and the first retardation compensation layer 12 shown in FIG. 2 was formed. As shown in FIG. 3, the first retardation compensation layer is a negative C-plate in which two kinds of vapor deposition films L1 and L2 are alternately stacked, and the retardation (d1Δn1) is a negative value. Then, by adjusting the overall physical film thickness d1 and the birefringence Δn1, the magnitude of the retardation (d1Δn1) can be arbitrarily determined to some extent, so that this value is “−341”. The phase difference compensation layer 12 was formed on the back surface of the glass substrate.

In addition, it is as follows if it supplements about this 1st phase difference compensation layer. Structural birefringence having negative birefringence Δn is obtained by alternately laminating thin films having refractive indexes n 1 and n 2 and physical thicknesses a and b at a pitch (a + b) sufficiently shorter than the wavelength. It is known to become a body. When electromagnetic waves are perpendicularly incident on this structural birefringent body, the electric field is only a wave (TE wave) that oscillates parallel to the plane of each layer, and thus does not exhibit birefringence. However, when electromagnetic waves are incident on the laminated surface of each layer at an angle, it is effective for the wave (TE wave component) in which the electric field vibrates parallel to each layer and the wave (TM wave component) in which the electric field vibrates perpendicularly to each layer. It is known that the refractive indexes N TE and N TM are different and are expressed by the following equations, respectively.
N TE = √ {(an 1 2 + bn 2 2 ) / (a + b)}
N TM = √ [(a + b) / {(a / n 1 2 ) + (b / n 2 2 )}]
The difference between these effective refractive indexes N TE and N TM is a factor causing birefringence, and the birefringence Δn is given by “Δn = N TM −N TE ”.

As can be seen from the above equation, the birefringence Δn1 can be determined by selecting the refractive indexes n 1 and n 2 of the vapor deposition layers L1 and L2 and the respective physical film thicknesses a and b. The total physical film thickness d1 can be determined by the number of repeated laminations of L2. Accordingly, the retardation (d1Δn1) value of the first retardation compensation layer can be set to an arbitrary value by selecting an appropriate material from among vapor deposition materials having light transmission characteristics and excellent vapor deposition suitability. It becomes possible to approach.

The glass substrate on which the first retardation compensation layer 12 was formed in this manner was taken out of the vacuum chamber, washed again with acetone and sufficiently dried, and then set in the vapor deposition apparatus shown in FIG. A second retardation compensation layer having a four-layer structure was deposited using the deposition surface as the uppermost layer of the first retardation compensation layer 12. In the first obliquely deposited film S1, the azimuth angle α was −46.5 °, the polar angle β was 14 °, and the retardation (dΔn) S1 was set to “106 nm”. The azimuth angle α of the second obliquely deposited film S2 is 135 °, the polar angle β is 45 °, and the retardation (dΔn) S2 is “111 nm”. Further, for the third and fourth oblique deposition films S3 and S4, the azimuth angles α are −42 ° and −45 °, the polar angles β are 10 ° and 12.5 °, and the retardation is “87 nm”. , “88 nm”, and after forming the second retardation compensation layer composed of these obliquely deposited films S1 to S4, a sample is taken out and reset to a normal front deposition apparatus to prevent reflection of the same three layers. A film (corresponding to the antireflection film 15 in FIG. 2) was formed.

As a vapor deposition material for the oblique vapor deposition films S < b > 1 to S < b > 4 constituting the second retardation compensation layer 14, ZrO 2 mixed with 10% by weight of TiO 2 was used. When forming the second retardation compensation layer 14, the vacuum chamber is evacuated to 1 × 10 −4 Pa, and then oxygen gas is introduced to 1 × 10 −2 Pa to sufficiently oxidize the film during film formation. Was done. The layer configurations of the first and second phase difference compensation layers of the phase difference compensation element 2 thus obtained and their parameters are summarized in the following table.

For each of the oblique vapor deposition films Si (i = 1 to 4) constituting the second retardation compensation layer 14, the vapor deposition direction Pi defined by the azimuth angle α and the polar angle β and the oblique vapor deposition film Si The optical axis vector Pi is defined from the retardation (dΔn) Si value determined from the birefringence and the film thickness. These optical axis vectors Pi are generally obtained by combining each retardation value (dΔn) Si with azimuth angle α i and polar angle β i .
Pi (x, y, z) = ((dΔn) Si × cos α i × tan β i ,
(dΔn) Si × sin α i × tan β i , (dΔn) Si )
It can be expressed as.

A projection vector Ai obtained by orthogonally projecting these optical axis vectors Pi onto the xy plane of FIG.
A 1 (x, y) = (18.29, −19.35)
A 2 (x, y) = (− 78.49, 78.49)
A 3 (x, y) = (11.64, 10.48)
A 4 (x, y) = (13.69, −13.69)
These are calculated as shown in FIG.

As can be seen from Table 1 and FIG. 7 above, what is characteristic about these projection vectors A 1 to A 4 is that the respective azimuth angles α of each of the projection vectors A 2 and A 4 (each oblique deposition). Are substantially equal to the azimuth angle of the optical axis of the film). In constructing the second retardation compensation layer 14, parameters such as the number of obliquely deposited films, the thickness of each layer, and the azimuth angle of the optical axis can be variously changed. As a result of conducting various studies, as described above, the second retardation layer 14 used in combination with the first retardation compensation layer 12 has a layer structure of three or more layers, and at least two layers thereof. It was confirmed that the azimuth angles of the optical axes that can be approximated by the azimuth angle of vapor deposition during oblique vapor deposition should be in a relationship of 180 ° with each other. In this embodiment, the direction of the azimuth angle α of the obliquely deposited films S2 and S4 is made to coincide with the azimuth of the transmission axis 3a of the polarizing plate 3 on the incident side.

  FIG. 8 shows light blocking characteristics when the phase difference compensating element 2 of the above embodiment is disposed between the polarizing plates 3 and 4 as shown in FIG. Although the viewing angle dependency remains, it can be seen that the brightness of the leaked light from the exit-side polarizing plate 4 is reduced as a whole. FIG. 9 shows the light blocking characteristics of the comparative sample. In this comparative example sample, the retardation of the first retardation compensation layer 12 is “−220 nm”, and a single-layer oblique deposition film is formed as the second retardation compensation layer 14. 135 ° ”and the retardation is“ 413 nm ”. By using a phase difference compensation element that combines a first phase difference compensation layer that becomes a negative C-plate and a second phase difference compensation layer that becomes a positive O-plate, as in this comparative example sample, Although it is known that the light blocking characteristics of a pair of Nicols arranged polarizing plates can be improved, the phase difference compensation element of the embodiment of the present invention has further improved light blocking characteristics than the comparative sample. Recognize.

  In preparing the retardation compensation element of the present invention having the first retardation compensation layer 12 and the second retardation compensation layer 14, the retardation value depending on the birefringence and the film thickness of the first retardation compensation layer 12. Parameters for obtaining the optimum light blocking characteristics such as the number of layers of the second retardation compensation layer 14, the birefringence and film thickness of each layer, and the azimuth angle of the optical axis of each layer (deposition azimuth angle of the oblique deposition film). Although the number of combinations is enormous, the second retardation compensation layer is composed of three or more oblique deposition films, and at least two of them are subjected to the azimuth of each optical axis, that is, oblique deposition. Setting the azimuth angles so as to have a 180 ° relationship with each other is effective in improving the light blocking characteristics.

  An example in which the phase difference compensating element 2 of the present invention is used in combination with a liquid crystal display device is shown in FIG. A TN liquid crystal 6 is used as a liquid crystal element for image display, and the retardation compensation element 2 of the present invention is inserted between the polarizing plate 3 on the incident side and the TN liquid crystal 6. The exit-side polarizing plate 4 is arranged in a crossed Nicols manner so that the direction of the transmission axis intersects the incident-side polarizing plate 3 at 90 °, and this liquid crystal display device is used in a normally white mode. The illumination light 34 becomes linearly polarized light by the polarizing plate 3 and passes through the phase difference compensation element 2, the TN liquid crystal 6 and the polarizing plate 4 and is emitted as image light 35. When the TN liquid crystal 6 is displayed in the dark, even if the illumination light 34 is not necessarily only a light beam parallel to the optical axis 5, the leakage light contained in the image light 35 is suppressed by the action of the phase difference compensation element 2 and is good. Light blocking characteristics can be obtained, and the viewing angle characteristics can be improved.

  Furthermore, in this embodiment, since the liquid crystal molecules filled between the pair of transparent substrates of the TN liquid crystal 6 exhibit birefringence, the first phase difference compensation layer of the phase difference compensation element 2 is considered in consideration of this. It is necessary to adjust the retardation value by 12. In other words, the first retardation compensation layer 12 has a compensation for the phase difference between the ordinary light and the extraordinary light birefringed by the liquid crystal molecules of the TN liquid crystal 6 in addition to the retardation compensation action for the light flux obliquely incident on the polarizing plate 3. Action is required. This retardation compensation can be adjusted by adjusting the thickness of the first retardation compensation layer 12 in accordance with the liquid crystal cell thickness of the TN liquid crystal 6.

  FIG. 11 shows an example in which the phase difference compensation element 2 of the present invention is applied to an off-axis liquid crystal display device using a reflective TN liquid crystal 36 for image display. The reflective TN liquid crystal 35 has a reflective surface on the back side of the liquid crystal cell, and the incident optical axis 5a and the outgoing optical axis 5b are different optical axes. The illumination light 34 that has passed through the polarizing plate 3 passes through the liquid crystal cell as linearly polarized incident light, is reflected by the reflecting surface, passes through the liquid crystal cell again, and becomes outgoing light. In consideration of use in the normally white mode, when the reflective TN liquid crystal 35 is in a dark display state, the thickness of the liquid crystal cell is determined so that the polarization directions of incident light and outgoing light are rotated by 90 °. The exit-side polarizing plate 4 has a crossed Nicols arrangement with respect to the polarizing plate 3.

  Also in such an off-axis type liquid crystal display device, by using the phase difference compensation element 2 of the present invention, the image light 35 emitted from the polarizing plate 4 when the reflective TN liquid crystal 36 is in a dark display state is used. The leakage light contained can be suppressed, and at the same time, the viewing angle characteristics can be improved. As in the embodiment of FIG. 10, the liquid crystal molecules of the reflective TN liquid crystal 36 exhibit birefringence, and the retardation value by the first retardation compensation layer 12 of the retardation compensation element 2 is adjusted in consideration of this. There is a need to. Since the reflective TN liquid crystal 36 is used, the thickness of the first retardation compensation layer 12 is adjusted in consideration that the optical path length in the liquid crystal cell is twice the actual cell thickness. .

  The retardation compensation element of the present invention is a full-color direct-view display that uses a single-plate TN liquid crystal as a display element when the reference wavelength for producing the first and second retardation compensation layers is set to 550 nm, for example. Can be used. However, since the birefringence effects of the liquid crystal molecules and the phase difference compensation element differ depending on the wavelength, it is desirable to change the film configuration of the phase difference compensation element for each reference wavelength of the component color light. In this case, the TN liquid crystal generally incorporates micro color filters that transmit red, green, and blue, which are component color lights, respectively. Therefore, three types of phase difference compensation with different film configurations corresponding to these filter elements. An element is preferably used.

  Changing the film configuration of the phase difference compensation element in accordance with the reference wavelength of the component color light can be effectively performed particularly in a three-plate type color liquid crystal projector using three TN liquid crystals for each component color light. FIG. 12 schematically shows the configuration of a three-plate color liquid crystal projector.

  In FIG. 12, on the three liquid crystal elements 50R, 50G, and 50B, black and white images having different transmission densities are displayed corresponding to the red, green, and blue component color light images, respectively. Radiated light from the light source 52 passes through a filter 53 that cuts ultraviolet rays and infrared rays to become white light including red light, green light, and blue light, and consists of a glass rod according to the illumination optical axis from the light source to the liquid crystal element. The light enters the integrator 54. The light incident surface of the integrator 54 is located in the vicinity of the focal position of the parabolic mirror used in the light source 52, and the light from the light source 52 is incident on the glass rod 54 with high efficiency.

  A relay lens 55 is disposed opposite to the emission surface of the glass rod 54, and white light from the glass rod 54 is incident on the mirror 57 as parallel light by the relay lens 55 and the subsequent collimating lens 56. The white light reflected by the mirror 57 is divided into two light beams by a dichroic mirror 58R that transmits only red light, and the transmitted red light is reflected by the mirror 59 to illuminate the liquid crystal element 50R from the back. Further, the green light and the blue light reflected by the dichroic mirror 58R are further divided into two light beams by the dichroic mirror 58G that reflects only the green light. The green light reflected by the dichroic mirror 58G illuminates the liquid crystal element 50G from the back side. The blue light transmitted through the dichroic mirror 58G is reflected by the mirrors 58B and 60, and illuminates the liquid crystal element 50B from the back.

  The liquid crystal elements 50R, 50G, and 50B are each composed of a TN liquid crystal, and a composite prism 64 is arranged so that the center is located at a position optically equidistant from the liquid crystal elements 50R, 50G, and 501B. A projection lens 65 is provided so as to face the emission surface. The composite prism 64 has two dichroic surfaces 64a and 64b inside thereof, and receives the red light transmitted through the liquid crystal element 50R, the green light transmitted through the liquid crystal element 50G, and the blue light transmitted through the liquid crystal element 50B. The combined image is incident on the projection lens 65. The projection lens 65 has its object-side focal plane coincident with the exit surfaces of the liquid crystal elements 50R, 50G, and 50B and its image-side focal plane coincides with the screen 70, so that the full color synthesized by the synthesizing prism 64 is provided. The image is formed on the screen 70.

  Polarizers 66R, 66G, and 66B and phase difference compensating elements 67R, 67G, and 67B of the present invention are provided on the light incident surface side of the liquid crystal elements 50R, 50G, and 50B, respectively. 68R, 68G, and 68B are provided. The polarizing plates 66R, 66G, and 66B on the light incident surface side and the polarizing plates 68R, 68G, and 68B on the light emitting surface side are in a crossed Nicols arrangement, and the polarizing plate on the light incident surface side is a polarizer and the light emitting surface side. The polarizing plate acts as an analyzer. In addition, the phase difference compensation elements 67R, 67G, and 67B include the first phase difference compensation layer and the second phase difference compensation layer as described above, and the liquid crystal elements 50R, 50G, and The phase difference caused by 50B is individually compensated, and at the same time, the light blocking function by the polarizing plates 66R, 66G, and 66B and the polarizing plates 68R, 68G, and 68B arranged in crossed Nicols is further improved.

Each of the liquid crystal elements 50R, 50G, and 50B is made of a completely common TN liquid crystal, but it is generally known that the retardation (dΔn) LC of the liquid crystal element varies depending on the wavelength. FIG. 13 shows an example of a TN liquid crystal having a liquid crystal layer thickness of 4.5 μm. The birefringence Δn changes according to the wavelength, and the retardation (dΔn) LC changes accordingly. In the figure, Re indicates the effective retardation when the ratio of liquid crystal molecules in the vertical alignment posture when a voltage is applied to the liquid crystal is 70%, and the first retardation compensation layer described above is based on this effective retardation Re. This is to compensate for a positive phase difference. Of course, the ratio of the liquid crystal molecules in the vertical orientation varies depending on factors such as the structure of the TN liquid crystal, the thickness of the liquid crystal, the density, and the saturation voltage value, and is not limited to 70%.

FIG. 14 is a schematic view showing a structure in which 80 TiO 2 films and SiO 2 films having physical film thicknesses of 30 nm and 20 nm are alternately laminated in a total of 80 layers in order to effectively compensate the effective retardation Re of the TN liquid crystal. The negative retardation (d1Δn1) of one phase difference compensation layer is represented by an absolute value. Since the refractive indexes of the TiO 2 film and the SiO 2 film, which are the vapor deposition materials, have wavelength dependence, the wavelength dependence naturally appears in the retardation. This first phase difference compensation layer is designed to perform good phase difference compensation at 550 nm, which has high visibility in the visible light region. However, as shown in FIG. You can see that compensation is not possible.

  Therefore, the feature of the first retardation compensation layer comprising a vapor deposition film that is sufficiently thin compared to the wavelength, that is, the negative birefringence Δn1 is determined by the refractive index and the film thickness ratio of the two types of vapor deposition films, and By utilizing the fact that the retardation value can be adjusted by adjusting the total film thickness (the number of stacked layers) multiplied by the birefringence Δn1, the present invention uses the first of the phase difference compensation elements 67R, 67G, 67B for each color channel. The thickness of the retardation compensation layer is changed. An example is shown in FIG.

In FIG. 16, the thickness of the first retardation compensation layer is changed for blue light, green light, and blue light. The vapor deposition films laminated on all the channels are TiO 2 films having physical film thicknesses of 30 nm and 20 nm. And SiO 2 film are all common. However, for blue light, the total number of layers is 72 and the total film thickness is d1 = 1.8 μm in accordance with the retardation of TN liquid crystal of 413 nm at the reference wavelength λ = 450 nm at the center of the blue component color light. Yes. Similarly, for green light, the total number of layers is 80 with a reference wavelength λ = 550 nm, and the total thickness is d1 = 2.0 μm. For red light, the total number of layers is 82 with a reference wavelength λ = 650 nm. Thus, the total film thickness d1 = 2.1 μm.

  As a result, as shown in FIG. 17, it can be seen that the retardation of the liquid crystal elements 50R, 50G, and 50B of the respective color channels can be favorably corrected for each wavelength range of the component color light. Therefore, for example, when a blue background is projected on the entire screen 70, the entire liquid crystal element 50B is displayed in the bright state and the remaining liquid crystal elements 50R and 50G are displayed in the dark state. The positive phase difference due to the birefringence action of the liquid crystal molecules vertically aligned by the liquid crystal elements 50R and 50G is applied to the red light and green light for the phase difference compensating elements 67R and 67G. Projected with a clear blue background with no color blur, since the output light is almost eliminated from the polarizing plates 68R and 68G as the analyzer, which is compensated well by the negative retardation of the one phase difference compensation layer. Can do.

  For the same reason, the contrast ratio between when white light is projected on the entire screen 70 and when it is completely dark is improved from the conventional 500: 1 to 700: 1, and even when a general full-color image is projected, the contrast ratio is improved. Can be tightened to improve the sharpness of the image. As can be seen from FIG. 17, the wavelength dependency of retardation is weaker for green light and red light than the first phase difference compensation layer for blue light. From this, it is also possible to apply a common layer having the same total film thickness as the first phase difference compensation layer for green light and red light. In this case, it is advantageous to determine the total film thickness on the basis of 600 nm.

As described above, when the retardation compensation element of the present invention is applied to a three-plate color liquid crystal projector, it is effective to adjust the total thickness of the first retardation compensation layer for at least two kinds of color channels. It is. The above description considers only the wavelength dependence of the retardation (dΔn) LC of the liquid crystal elements 50R, 50G, and 50B. Each phase difference compensation element 67R, 67G, and 67B includes a second phase difference compensation layer. Is also formed. Since these second retardation compensation layers also have different reference wavelengths for each color channel, a film design corresponding to the reference wavelength is performed. However, this second retardation compensation layer exhibits a positive retardation like liquid crystal molecules. Have. Therefore, it is desirable to adjust the total film thickness of the first retardation compensation layer in a further increasing direction.

  When the phase difference compensation elements 67R, 67G, and 67B optimized for the first and second phase difference compensation layers corresponding to the reference wavelength of each color channel are used, the contrast ratio on the screen 70 becomes 1000: 1 or more. I can expect that. In addition, it is composed of only inorganic materials, so there is no problem in terms of heat resistance and light resistance, and it can be used effectively for products that are expected to be used for a long time, such as household rear projection televisions. Is possible.

  As described above, the present invention has been described based on the illustrated embodiment. As a polarizer for generating linearly polarized light and an analyzer for obtaining a light blocking action according to the polarization direction, a wire other than a polarizing plate is used. It is also possible to use a grid polarizing element. Further, the first retardation compensation layer is not limited to the above-described multilayer deposited film, but may be a polymer produced from, for example, a short pitch cholesteric liquid crystal. That is, a layer having a structure equivalent to that of cholesteric liquid crystal in which the pitch of the helical structure of liquid crystal molecules is about 1/10 to 1/5 of the light wavelength and the helical axis is perpendicular to the substrate is negative. It is known to act as a C-plate. Therefore, the surface of the substrate is subjected to an alignment treatment so that the major axis thereof is parallel to the major axis, and a cholesteric liquid crystal having a polymerizable molecular structure is applied on the substrate to form the above-described cholesteric structure, and then light is applied. If a film such as polymerization is applied to form a film that has lost its fluidity, it can be applied to the first retardation compensation layer.

  Furthermore, it is also possible to apply a positive C-plate to the first retardation compensation layer. In this case, an alignment treatment is performed on the surface of the substrate so that the major axis of the liquid crystal molecules is perpendicular to the polymerization. If a rod-like liquid crystal monomer having a molecular structure is applied onto the substrate and a monodomain alignment film is formed, then a process such as photopolymerization is performed to produce a film that loses its fluidity as it is. The film can be used as the first retardation compensation layer.

  In addition to the glass substrate, various transparent inorganic materials can be used as the substrate for forming the retardation compensation element of the present invention, and a sapphire substrate having a high thermal conductivity particularly when considering application to a liquid crystal projector. A quartz substrate or the like can be used. Also, the first retardation compensation layer and the second retardation compensation layer are formed on separate transparent substrates, or the transparent substrate on which the first and second retardation compensation layers are formed is attached to a polarizing plate and integrated. Furthermore, as these transparent substrates, lenses, prisms, various filters and liquid crystal element substrates incorporated in the optical system can be used in combination.

It is a conceptual diagram of the optical system for function confirmation of the phase difference compensation element using this invention. It is a schematic sectional drawing of the phase difference compensation element of this invention. It is a conceptual diagram which shows the layer structure of a 1st phase difference compensation layer. It is a conceptual diagram which shows the layer structure of a 2nd phase difference compensation layer. It is the schematic which shows the vapor deposition apparatus used for film-forming of an oblique vapor deposition film | membrane. It is explanatory drawing which shows the azimuth and polar angle of an oblique vapor deposition film. It is explanatory drawing of the projection vector which orthogonally projected the optical axis vector of the oblique vapor deposition film on xy plane. It is an isoluminance curve diagram showing the light blocking characteristic by the phase difference compensation element of the present invention. It is an equiluminance curve figure showing the light interception characteristic of the phase difference compensation element of a comparative example. It is the schematic which applied the phase difference compensation element of this invention to the liquid crystal display device using the transmissive | pervious TN liquid crystal. It is the schematic which applied the phase difference compensation element of this invention to the liquid crystal display device using reflection type TN liquid crystal. 1 is a schematic view of a three-plate color liquid crystal projector using the present invention. It is a graph which shows the wavelength dependence of the retardation of TN liquid crystal. It is a graph which shows the wavelength dependence of a 1st phase difference compensation layer. It is a graph which shows the retardation characteristic of TN liquid crystal and a 1st phase difference compensation layer. It is a graph which shows the wavelength dependence of the improved 1st phase difference compensation layer. It is a graph which shows the retardation characteristic of the improved 1st phase difference compensation layer. It is an equiluminance curve figure which shows the light-shielding characteristic of a pair of polarizing plate arrange | positioned by cross nicol.

Explanation of symbols

2 Phase Compensation Element 3, 4 Polarizer 10 Glass Substrate 12 First Phase Compensation Layer 14 Second Phase Compensation Layer 15, 16 Antireflection Layer 22, 23 Deposition Material 25 Electron Gun 30 Substrate Holder 31 Film Thickness Monitor 32 Ellipsometer 50R, 50G, 50B Liquid crystal element 58R, 58G, 58B Dichroic mirror 65 Projection lens 67R, 67G, 67B Phase compensation element 70 Screen

Claims (11)

  1. In the phase difference compensation element used by being arranged between a pair of polarizing elements arranged in crossed Nicols,
    A transparent substrate disposed perpendicular to the optical axis perpendicular to the pair of polarizing elements, a first retardation compensation layer supported by the transparent substrate and having an optical axis perpendicular to the transparent substrate, and an optical axis being a transparent substrate A second retardation compensation layer composed of a multilayer film of three or more layers each inclined with respect to the normal line of
    A phase difference compensation element characterized in that the orientations when the optical axes of at least two layers of the multilayer film constituting the second phase difference compensation layer are orthogonally projected onto a transparent substrate are substantially opposed to each other.
  2.   2. The retardation compensation element according to claim 1, wherein each of the first and second retardation compensation layers is made of an inorganic material.
  3.   3. The retardation compensation element according to claim 2, wherein each layer constituting the second retardation compensation layer is an obliquely deposited film.
  4.   4. The phase difference compensation element according to claim 3, wherein at least one of the optical axes of the layers constituting the second phase difference compensation layer is different from the optical axes of the other layers.
  5.   The first retardation compensation layer includes a vapor deposition film in which a high refractive index material and a low refractive index material are alternately stacked, and each optical film thickness is 1/100 to 1/5 of a reference wavelength. The phase difference compensation element according to claim 2, wherein the phase difference compensation element is provided.
  6.   The orientation when the optical axis of any one of the multilayer films constituting the second retardation compensation layer is orthogonally projected onto the transparent substrate is aligned with the orientation of the transmission axis of the polarizing element on the incident side. The phase difference compensating element according to any one of claims 2 to 5.
  7.   The phase difference compensating element according to claim 1, wherein an antireflection layer is provided on at least one of the light incident surface side and the light emitting surface side.
  8.   8. A light modulation system, wherein a liquid crystal cell is disposed on the exit surface side of the phase difference compensating element according to claim 6.
  9.   8. A liquid crystal display device, wherein a transmission type liquid crystal cell is disposed on the exit surface side of the phase difference compensator according to claim 6 or 7.
  10.   8. A liquid crystal projector comprising: a transmissive liquid crystal cell disposed on an emission surface side of the phase difference compensating element according to claim 6; and modulating light from the liquid crystal cell projected onto a screen through a projection lens.
  11. A reflection type liquid crystal cell is disposed on the exit surface side of the phase difference compensating element according to claim 6, and modulated light from the liquid crystal cell is projected onto a screen through an off-axis projection lens. LCD projector.
JP2004363306A 2004-12-15 2004-12-15 Phase difference compensation element, optical modulation system, liquid crystal display device, and liquid crystal projector Pending JP2006171328A (en)

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PCT/JP2005/023424 WO2006064956A1 (en) 2004-12-15 2005-12-14 Phase difference compensator, light modurating system, liquid crystal display and liquid crystal projector
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